17,624 results on '"KIM, JEONG"'
Search Results
2. Gravitational Wave Duet by Resonating Binary Black Holes with Axion-Like Particles
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Kim, Jeong Han and Yang, Xing-Yu
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Astrophysics - Cosmology and Nongalactic Astrophysics ,Astrophysics - High Energy Astrophysical Phenomena ,General Relativity and Quantum Cosmology ,High Energy Physics - Phenomenology - Abstract
We leverage gravitational wave observations to explore physics beyond the Standard Model, focusing on axion-like particles (ALPs). This study investigates the resonant effects of ALPs with binary black hole systems, where their oscillatory nature induces time-dependent forces on the black holes. By employing a detailed Fisher matrix analysis, we not only probe a new parameter space for ALPs, characterized by their mass and decay constants, but also assess how these parameters affect gravitational waveforms during black hole mergers. Our approach is distinct as it does not assume interactions of ALPs with photons or nucleons. We demonstrate that as binary black holes spiral inward and lose energy, their orbital frequencies may resonate with those of ALPs, producing distinct oscillatory patterns in gravitational waves detectable by upcoming experiments such as the Laser Interferometer Space Antenna (LISA). This work broadens the potential of gravitational wave astronomy as a tool for dark matter searches, offering a promising avenue for studying elusive components of the universe., Comment: 11 pages, 9 figures
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- 2024
3. Structural insights into GABAA receptor potentiation by Quaalude.
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Chojnacka, Weronika, Teng, Jinfeng, Kim, Jeong, Jensen, Anders, and Hibbs, Ryan
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Receptors ,GABA-A ,Binding Sites ,Cryoelectron Microscopy ,Humans ,Animals ,Etomidate ,Propofol ,Quinazolinones ,Allosteric Regulation ,HEK293 Cells ,Hypnotics and Sedatives - Abstract
Methaqualone, a quinazolinone marketed commercially as Quaalude, is a central nervous system depressant that was used clinically as a sedative-hypnotic, then became a notorious recreational drug in the 1960s-80s. Due to its high abuse potential, medical use of methaqualone was eventually prohibited, yet it persists as a globally abused substance. Methaqualone principally targets GABAA receptors, which are the major inhibitory neurotransmitter-gated ion channels in the brain. The restricted status and limited accessibility of methaqualone have contributed to its pharmacology being understudied. Here, we use cryo-EM to localize the GABAA receptor binding sites of methaqualone and its more potent derivative, PPTQ, to the same intersubunit transmembrane sites targeted by the general anesthetics propofol and etomidate. Both methaqualone and PPTQ insert more deeply into subunit interfaces than the previously-characterized modulators. Binding of quinazolinones to this site results in widening of the extracellular half of the ion-conducting pore, following a trend among positive allosteric modulators in destabilizing the hydrophobic activation gate in the pore as a mechanism for receptor potentiation. These insights shed light on the underexplored pharmacology of quinazolinones and further elucidate the molecular mechanisms of allosteric GABAA receptor modulation through transmembrane binding sites.
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- 2024
4. Entanglement witness and nonlocality in confidence of measurement from multipartite quantum state discrimination
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Ha, Donghoon and Kim, Jeong San
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Quantum Physics - Abstract
We consider multipartite quantum state discrimination and provide a specific relation between the properties of entanglement witness and quantum nonlocality inherent in the confidence of measurements. We first provide the definition of the confidence of measurements as well as its useful properties for various types of multipartite measurements. We show that globally maximum confidence that cannot be achieved by local operations and classical communication strongly depends on the existence of entanglement witness. We also provide conditions for an upper bound on maximum of locally-achievable confidences. Finally, we establish a method in terms of entanglement witness to construct quantum state ensemble with nonlocal maximum confidences., Comment: 12 pages, no figure
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- 2024
5. Metallicity Dependence of Pressure-Regulated Feedback-Modulated Star Formation in the TIGRESS-NCR Simulation Suite
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Kim, Chang-Goo, Ostriker, Eve C., Kim, Jeong-Gyu, Gong, Munan, Bryan, Greg L., Fielding, Drummond B., Hassan, Sultan, Ho, Matthew, Jeffreson, Sarah M. R., Somerville, Rachel S., and Steinwandel, Ulrich P.
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Astrophysics - Astrophysics of Galaxies - Abstract
We present a new simulation suite for the star-forming interstellar medium (ISM) in galactic disks using the TIGRESS-NCR framework. Distinctive aspects of our simulation suite are: (1) sophisticated and comprehensive numerical treatments of essential physical processes including magnetohydrodynamics, self-gravity, and galactic differential rotation, as well as photochemistry, cooling, and heating coupled with ray-tracing UV radiation transfer and resolved supernova feedback and (2) wide parameter coverage including metallicity over $Z'\equiv Z/Z_\odot\sim0.1-3$, gas surface density $\Sigma_{\rm gas}\sim5-150 M_{\odot}{\rm pc^{-2}}$, and stellar surface density $\Sigma_{\rm star}\sim 1-50 M_{\odot}{\rm pc^{-2}}$. The range of emergent star formation rate surface density is $\Sigma_{\rm SFR}\sim 10^{-4}-0.5 M_{\odot}{\rm kpc^{-2}yr^{-1}}$ and ISM total midplane pressure is $P_{\rm tot}/k_B=10^3-10^6{\rm cm^{-3}K}$, with $P_{\rm tot}$ equal to the ISM weight $W$. For given $\Sigma_{\rm gas}$ and $\Sigma_{\rm star}$, we find $\Sigma_{\rm SFR} \propto Z'^{0.3}$. We provide an interpretation based on the pressure-regulated feedback-modulated (PRFM) star formation theory. We characterize feedback modulation in terms of the yield $\Upsilon$, defined as the ratio of each stress to $\Sigma_{\rm SFR}$. The thermal feedback yield varies sensitively with both weight and metallicity as $\Upsilon_{\rm th}\propto W^{-0.46}Z'^{-0.53}$, while the combined turbulent and magnetic feedback yield shows weaker dependence $\Upsilon_{\rm turb+mag}\propto W^{-0.22}Z'^{-0.18}$. The reduction in $\Sigma_{\rm SFR}$ at low metallicity is due mainly to enhanced thermal feedback yield, resulting from reduced attenuation of UV radiation. With the metallicity-dependent calibrations we provide, PRFM theory can be used for a new subgrid star formation prescription in cosmological simulations where the ISM is unresolved., Comment: Resubmitted to ApJ after minor revision
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- 2024
6. Visuo-Tactile Keypoint Correspondences for Object Manipulation
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Kim, Jeong-Jung, Koh, Doo-Yeol, and Kim, Chang-Hyun
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Computer Science - Robotics - Abstract
This paper presents a novel manipulation strategy that uses keypoint correspondences extracted from visuo-tactile sensor images to facilitate precise object manipulation. Our approach uses the visuo-tactile feedback to guide the robot's actions for accurate object grasping and placement, eliminating the need for post-grasp adjustments and extensive training. This method provides an improvement in deployment efficiency, addressing the challenges of manipulation tasks in environments where object locations are not predefined. We validate the effectiveness of our strategy through experiments demonstrating the extraction of keypoint correspondences and their application to real-world tasks such as block alignment and gear insertion, which require millimeter-level precision. The results show an average error margin significantly lower than that of traditional vision-based methods, which is sufficient to achieve the target tasks.
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- 2024
7. Geometry, Dissipation, Cooling, and the Dynamical Evolution of Wind-Blown Bubbles
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Lancaster, Lachlan, Ostriker, Eve C., Kim, Chang-Goo, Kim, Jeong-Gyu, and Bryan, Greg L.
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Astrophysics - Astrophysics of Galaxies - Abstract
Bubbles driven by energy and mass injection from small scales are ubiquitous in astrophysical fluid systems and essential to feedback across multiple scales. In particular, O stars in young clusters produce high velocity winds that create hot bubbles in the surrounding gas. We demonstrate that the dynamical evolution of these bubbles is critically dependent upon the geometry of their interfaces with their surroundings and the nature of heat transport across these interfaces. These factors together determine the amount of energy that can be lost from the interior through cooling at the interface, which in turn determines the ability of the bubble to do work on its surroundings. We further demonstrate that the scales relevant to physical dissipation across this interface are extremely difficult to resolve in global numerical simulations of bubbles for parameter values of interest. This means the dissipation driving evolution of these bubbles in numerical simulations is often of a numerical nature. We describe the physical and numerical principles that determine the level of dissipation in these simulations; we use this, along with a fractal model for the geometry of the interfaces, to explain differences in convergence behavior between hydrodynamical and magneto-hydrodynamical simulations presented here. We additionally derive an expression for momentum as a function of bubble radius expected when the relevant dissipative scales are resolved and show that it still results in efficiently-cooled solutions as postulated in previous work., Comment: 41 pages, 20 figures, submitted to ApJ, comments welcome
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- 2024
8. Accuracy enhancement method for speech emotion recognition from spectrogram using temporal frequency correlation and positional information learning through knowledge transfer
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Kim, Jeong-Yoon and Lee, Seung-Ho
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Computer Science - Sound ,Computer Science - Computer Vision and Pattern Recognition ,Electrical Engineering and Systems Science - Audio and Speech Processing - Abstract
In this paper, we propose a method to improve the accuracy of speech emotion recognition (SER) by using vision transformer (ViT) to attend to the correlation of frequency (y-axis) with time (x-axis) in spectrogram and transferring positional information between ViT through knowledge transfer. The proposed method has the following originality i) We use vertically segmented patches of log-Mel spectrogram to analyze the correlation of frequencies over time. This type of patch allows us to correlate the most relevant frequencies for a particular emotion with the time they were uttered. ii) We propose the use of image coordinate encoding, an absolute positional encoding suitable for ViT. By normalizing the x, y coordinates of the image to -1 to 1 and concatenating them to the image, we can effectively provide valid absolute positional information for ViT. iii) Through feature map matching, the locality and location information of the teacher network is effectively transmitted to the student network. Teacher network is a ViT that contains locality of convolutional stem and absolute position information through image coordinate encoding, and student network is a structure that lacks positional encoding in the basic ViT structure. In feature map matching stage, we train through the mean absolute error (L1 loss) to minimize the difference between the feature maps of the two networks. To validate the proposed method, three emotion datasets (SAVEE, EmoDB, and CREMA-D) consisting of speech were converted into log-Mel spectrograms for comparison experiments. The experimental results show that the proposed method significantly outperforms the state-of-the-art methods in terms of weighted accuracy while requiring significantly fewer floating point operations (FLOPs). Overall, the proposed method offers an promising solution for SER by providing improved efficiency and performance.
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- 2024
9. Multi-player quantum data hiding by nonlocal quantum state ensembles
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Ha, Donghoon and Kim, Jeong San
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Quantum Physics - Abstract
We provide multi-player quantum data hiding based on nonlocal quantum state ensembles arising from multi-party quantum state discrimination. Using bounds on local minimum-error discrimination of multi-party quantum states, we construct a multi-player quantum data-hiding scheme. Our data-hiding scheme can be used to hide multiple bits, asymptotically, unless all the players collaborate. We also illustrate our results by examples of nonlocal quantum state ensembles., Comment: 11 pages, 3 figures. arXiv admin note: text overlap with arXiv:2311.06029
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- 2024
10. EUSO-SPB1 Mission and Science
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Collaboration, JEM-EUSO, Abdellaoui, G., Abe, S., Adams. Jr., J. H., Allard, D., Alonso, G., Anchordoqui, L., Anzalone, A., Arnone, E., Asano, K., Attallah, R., Attoui, H., Pernas, M. Ave, Bachmann, R., Bacholle, S., Bagheri, M., Bakiri, M., Baláz, J., Barghini, D., Bartocci, S., Battisti, M., Bayer, J., Beldjilali, B., Belenguer, T., Belkhalfa, N., Bellotti, R., Belov, A. A., Benmessai, K., Bertaina, M., Bertone, P. F., Biermann, P. L., Bisconti, F., Blaksley, C., Blanc, N., Blin-Bondil, S., Bobik, P., Bogomilov, M., Bolmgren, K., Bozzo, E., Briz, S., Bruno, A., Caballero, K. S., Cafagna, F., Cambié, G., Campana, D., Capdevielle, J. N., Capel, F., Caramete, A., Caramete, L., Caruso, R., Casolino, M., Cassardo, C., Castellina, A., Catalano, O., Cellino, A., Černý, K., Chikawa, M., Chiritoi, G., Christl, M. J., Colalillo, R., Conti, L., Cotto, G., Crawford, H. J., Cremonini, R., Creusot, A., Cummings, A., Gónzalez, A. de Castro, de la Taille, C., del Peral, L., Desiato, J., Damian, A. Diaz, Diesing, R., Dinaucourt, P., Djakonow, A., Djemil, T., Ebersoldt, A., Ebisuzaki, T., Eser, J., Fenu, F., Fernández-González, S., Ferrarese, S., Filippatos, G., Finch, W., Fornaro, C., Fouka, M., Franceschi, A., Franchini, S., Fuglesang, C., Fujii, T., Fukushima, M., Galeotti, P., García-Ortega, E., Gardiol, D., Garipov, G. K., Gascón, E., Gazda, E., Genci, J., Golzio, A., Gorodetzky, P., Gregg, R., Green, A., Guarino, F., Guépin, C., Guzmán, A., Hachisu, Y., Haungs, A., Heigbes, T., Carretero, J. Hernández, Hulett, L., Ikeda, D., Inoue, N., Inoue, S., Isgrò, F., Itow, Y., Jammer, T., Jeong, S., Jochum, J., Joven, E., Judd, E. G., Jung, A., Kajino, F., Kajino, T., Kalli, S., Kaneko, I., Kasztelan, M., Katahira, K., Kawai, K., Kawasaki, Y., Kedadra, A., Khales, H., Khrenov, B. A., Kim, Jeong-Sook, Kim, Soon-Wook, Kleifges, M., Klimov, P. A., Kreykenbohm, I., Krizmanic, J. F., Królik, K., Kungel, V., Kurihara, Y., Kusenko, A., Kuznetsov, E., Lahmar, H., Lakhdari, F., Licandro, J., Campano, L. López, Martínez, F. López, Mackovjak, S., Mahdi, M., Mandát, D., Manfrin, M., Marcelli, L., Marcos, J. L., Marszał, W., Martín, Y., Martinez, O., Mase, K., Mastafa, M., Matthews, J. N., Mebarki, N., Medina-Tanco, G., Menshikov, A., Merino, A., Mese, M., Meseguer, J., Meyer, S. S., Mimouni, J., Miyamoto, H., Mizumoto, Y., Monaco, A., Ríos, J. A. Morales de los, Nachtman, J. M., Nagataki, S., Naitamor, S., Napolitano, T., Neronov, A., Nomoto, K., Nonaka, T., Ogawa, T., Ogio, S., Ohmori, H., Olinto, A. V., Onel, Y., Osteria, G., Otte, A. N., Pagliaro, A., Painter, W., Panasyuk, M. I., Panico, B., Parizot, E., Park, I. H., Pastircak, B., Paul, T., Pech, M., Pérez-Grande, I., Perfetto, F., Peter, T., Picozza, P., Pindado, S., Piotrowski, L. W., Piraino, S., Plebaniak, Z., Pollini, A., Popescu, E. M., Prevete, R., Prévôt, G., Prieto, H., Przybylak, M., Puehlhofer, G., Putis, M., Reardon, P., Reno, M. H., Reyes, M., Ricci, M., Frías, M. D. Rodríguez, Matamala, O. F. Romero, Ronga, F., Sabau, M. D., Saccá, G., Sagawa, H., Sahnoune, Z., Saito, A., Sakaki, N., Salazar, H., Sánchez, J. L., Balanzar, J. C. Sanchez, Santangelo, A., Sanz-Andrés, A., Saprykin, O. A., Sarazin, F., Sato, M., Scagliola, A., Schanz, T., Schieler, H., Schovánek, P., Scotti, V., Serra, M., Sharakin, S. A., Shimizu, H. M., Shinozaki, K., Soriano, J. F., Sotgiu, A., Stan, I., Strharský, I., Sugiyama, N., Supanitsky, D., Suzuki, M., Szabelski, J., Tajima, N., Tajima, T., Takahashi, Y., Takeda, M., Takizawa, Y., Talai, M. C., Tameda, Y., Tenzer, C., Thomas, S. B., Tibolla, O., Tkachev, L. G., Tomida, T., Tone, N., Toscano, S., Traïche, M., Tsunesada, Y., Tsuno, K., Turriziani, S., Uchihori, Y., Valdés-Galicia, J. F., Vallania, P., Valore, L., Vankova-Kirilova, G., Venters, T. M., Vigorito, C., Villaseñor, L., Vlcek, B., von Ballmoos, P., Vrabel, M., Wada, S., Watanabe, J., Watts. Jr., J., Muñoz, R. Weigand, Weindl, A., Wiencke, L., Wille, M., Wilms, J., Yamamoto, T., Yang, J., Yano, H., Yashin, I. V., Yonetoku, D., Yoshida, S., Young, R., Zgura, I. S., Zotov, M. Yu., and Marchi, A. Zuccaro
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Astrophysics - Instrumentation and Methods for Astrophysics ,Astrophysics - High Energy Astrophysical Phenomena - Abstract
The Extreme Universe Space Observatory on a Super Pressure Balloon 1 (EUSO-SPB1) was launched in 2017 April from Wanaka, New Zealand. The plan of this mission of opportunity on a NASA super pressure balloon test flight was to circle the southern hemisphere. The primary scientific goal was to make the first observations of ultra-high-energy cosmic-ray extensive air showers (EASs) by looking down on the atmosphere with an ultraviolet (UV) fluorescence telescope from suborbital altitude (33~km). After 12~days and 4~hours aloft, the flight was terminated prematurely in the Pacific Ocean. Before the flight, the instrument was tested extensively in the West Desert of Utah, USA, with UV point sources and lasers. The test results indicated that the instrument had sensitivity to EASs of approximately 3 EeV. Simulations of the telescope system, telescope on time, and realized flight trajectory predicted an observation of about 1 event assuming clear sky conditions. The effects of high clouds were estimated to reduce this value by approximately a factor of 2. A manual search and a machine-learning-based search did not find any EAS signals in these data. Here we review the EUSO-SPB1 instrument and flight and the EAS search., Comment: 18 pages, 19 figures
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- 2024
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11. Warm Surprises from Cold Duets: N-Body Simulations with Two-Component Dark Matter
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Kim, Jeong Han, Kong, Kyoungchul, Lim, Se Hwan, and Park, Jong-Chul
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High Energy Physics - Phenomenology ,Astrophysics - Cosmology and Nongalactic Astrophysics ,Astrophysics - High Energy Astrophysical Phenomena - Abstract
We explore extensive N-body simulations with two-component cold dark matter candidates. We delve into the temperature evolution, power spectrum, density perturbation, and maximum circular velocity functions. We find that the substantial mass difference between the two candidates and the annihilation of the heavier components to the lighter ones effectively endow the latter with warm dark matter-like behavior, taking advantage of all distinct features that warm dark matter candidates offer, without observational bounds on the warm dark matter mass. Moreover, we demonstrate that the two-component dark matter model aligns well with observational data, providing valuable insights into where and how to search for the elusive dark matter candidates in terrestrial experiments., Comment: 7 pages, 5 figures
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- 2023
12. An Easy-to-Use Machine Learning Model to Predict the Prognosis of Patients With COVID-19: Retrospective Cohort Study
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Kim, Hyung-Jun, Han, Deokjae, Kim, Jeong-Han, Kim, Daehyun, Ha, Beomman, Seog, Woong, Lee, Yeon-Kyeng, Lim, Dosang, Hong, Sung Ok, Park, Mi-Jin, and Heo, JoonNyung
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Computer applications to medicine. Medical informatics ,R858-859.7 ,Public aspects of medicine ,RA1-1270 - Abstract
BackgroundPrioritizing patients in need of intensive care is necessary to reduce the mortality rate during the COVID-19 pandemic. Although several scoring methods have been introduced, many require laboratory or radiographic findings that are not always easily available. ObjectiveThe purpose of this study was to develop a machine learning model that predicts the need for intensive care for patients with COVID-19 using easily obtainable characteristics—baseline demographics, comorbidities, and symptoms. MethodsA retrospective study was performed using a nationwide cohort in South Korea. Patients admitted to 100 hospitals from January 25, 2020, to June 3, 2020, were included. Patient information was collected retrospectively by the attending physicians in each hospital and uploaded to an online case report form. Variables that could be easily provided were extracted. The variables were age, sex, smoking history, body temperature, comorbidities, activities of daily living, and symptoms. The primary outcome was the need for intensive care, defined as admission to the intensive care unit, use of extracorporeal life support, mechanical ventilation, vasopressors, or death within 30 days of hospitalization. Patients admitted until March 20, 2020, were included in the derivation group to develop prediction models using an automated machine learning technique. The models were externally validated in patients admitted after March 21, 2020. The machine learning model with the best discrimination performance was selected and compared against the CURB-65 (confusion, urea, respiratory rate, blood pressure, and 65 years of age or older) score using the area under the receiver operating characteristic curve (AUC). ResultsA total of 4787 patients were included in the analysis, of which 3294 were assigned to the derivation group and 1493 to the validation group. Among the 4787 patients, 460 (9.6%) patients needed intensive care. Of the 55 machine learning models developed, the XGBoost model revealed the highest discrimination performance. The AUC of the XGBoost model was 0.897 (95% CI 0.877-0.917) for the derivation group and 0.885 (95% CI 0.855-0.915) for the validation group. Both the AUCs were superior to those of CURB-65, which were 0.836 (95% CI 0.825-0.847) and 0.843 (95% CI 0.829-0.857), respectively. ConclusionsWe developed a machine learning model comprising simple patient-provided characteristics, which can efficiently predict the need for intensive care among patients with COVID-19.
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- 2020
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13. Relationships Between Smartphone Addiction and Impulsivity, Depression, and Intention to Use Smartphones among College Students: Mediating Effect of Parent-Adolescent Communication
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Kim, Jeong-yeon
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- 2018
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14. Clinical Genomic Sequencing Reports in Electronic Health Record Systems Based on International Standards: Implementation Study
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Ryu, Borim, Shin, Soo-Yong, Baek, Rong-Min, Kim, Jeong-Whun, Heo, Eunyoung, Kang, Inchul, Yang, Joshua SungWoo, and Yoo, Sooyoung
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Computer applications to medicine. Medical informatics ,R858-859.7 ,Public aspects of medicine ,RA1-1270 - Abstract
BackgroundTo implement standardized machine-processable clinical sequencing reports in an electronic health record (EHR) system, the International Organization for Standardization Technical Specification (ISO/TS) 20428 international standard was proposed for a structured template. However, there are no standard implementation guidelines for data items from the proposed standard at the clinical site and no guidelines or references for implementing gene sequencing data results for clinical use. This is a significant challenge for implementation and application of these standards at individual sites. ObjectiveThis study examines the field utilization of genetic test reports by designing the Health Level 7 (HL7) Fast Healthcare Interoperability Resources (FHIR) for genomic data elements based on the ISO/TS 20428 standard published as the standard for genomic test reports. The goal of this pilot is to facilitate the reporting and viewing of genomic data for clinical applications. FHIR Genomics resources predominantly focus on transmitting or representing sequencing data, which is of less clinical value. MethodsIn this study, we describe the practical implementation of ISO/TS 20428 using HL7 FHIR Genomics implementation guidance to efficiently deliver the required genomic sequencing results to clinicians through an EHR system. ResultsWe successfully administered a structured genomic sequencing report in a tertiary hospital in Korea based on international standards. In total, 90 FHIR resources were used. Among 41 resources for the required fields, 26 were reused and 15 were extended. For the optional fields, 28 were reused and 21 were extended. ConclusionsTo share and apply genomic sequencing data in both clinical practice and translational research, it is essential to identify the applicability of the standard-based information system in a practical setting. This prototyping work shows that reporting data from clinical genomics sequencing can be effectively implemented into an EHR system using the existing ISO/TS 20428 standard and FHIR resources.
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- 2020
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15. Multi-level, forming and filament free, bulk switching trilayer RRAM for neuromorphic computing at the edge
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Park, Jaeseoung, Kumar, Ashwani, Zhou, Yucheng, Oh, Sangheon, Kim, Jeong-Hoon, Shi, Yuhan, Jain, Soumil, Hota, Gopabandhu, Qiu, Erbin, Nagle, Amelie L, Schuller, Ivan K, Schuman, Catherine D, Cauwenberghs, Gert, and Kuzum, Duygu
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Information and Computing Sciences ,Engineering ,Nanotechnology ,Bioengineering ,Affordable and Clean Energy - Abstract
CMOS-RRAM integration holds great promise for low energy and high throughput neuromorphic computing. However, most RRAM technologies relying on filamentary switching suffer from variations and noise, leading to computational accuracy loss, increased energy consumption, and overhead by expensive program and verify schemes. We developed a filament-free, bulk switching RRAM technology to address these challenges. We systematically engineered a trilayer metal-oxide stack and investigated the switching characteristics of RRAM with varying thicknesses and oxygen vacancy distributions to achieve reliable bulk switching without any filament formation. We demonstrated bulk switching at megaohm regime with high current nonlinearity, up to 100 levels without compliance current. We developed a neuromorphic compute-in-memory platform and showcased edge computing by implementing a spiking neural network for an autonomous navigation/racing task. Our work addresses challenges posed by existing RRAM technologies and paves the way for neuromorphic computing at the edge under strict size, weight, and power constraints.
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- 2024
16. Nonlocal quantum state ensembles and quantum data hiding
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Ha, Donghoon and Kim, Jeong San
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Quantum Physics - Abstract
We consider the discrimination of bipartite quantum states and establish a relation between nonlocal quantum state ensemble and quantum data hiding processing. Using a bound on optimal local discrimination of bipartite quantum states, we provide a sufficient condition for a bipartite quantum state ensemble to be used to construct a quantum data-hiding scheme. Our results are illustrated by examples in multidimensional bipartite quantum systems., Comment: 11 pages, 4 figures
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- 2023
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17. Multi-level, Forming Free, Bulk Switching Trilayer RRAM for Neuromorphic Computing at the Edge
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Park, Jaeseoung, Kumar, Ashwani, Zhou, Yucheng, Oh, Sangheon, Kim, Jeong-Hoon, Shi, Yuhan, Jain, Soumil, Hota, Gopabandhu, Nagle, Amelie L., Schuman, Catherine D., Cauwenberghs, Gert, and Kuzum, Duygu
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Computer Science - Emerging Technologies ,Condensed Matter - Disordered Systems and Neural Networks ,Computer Science - Neural and Evolutionary Computing - Abstract
Resistive memory-based reconfigurable systems constructed by CMOS-RRAM integration hold great promise for low energy and high throughput neuromorphic computing. However, most RRAM technologies relying on filamentary switching suffer from variations and noise leading to computational accuracy loss, increased energy consumption, and overhead by expensive program and verify schemes. Low ON-state resistance of filamentary RRAM devices further increases the energy consumption due to high-current read and write operations, and limits the array size and parallel multiply & accumulate operations. High-forming voltages needed for filamentary RRAM are not compatible with advanced CMOS technology nodes. To address all these challenges, we developed a forming-free and bulk switching RRAM technology based on a trilayer metal-oxide stack. We systematically engineered a trilayer metal-oxide RRAM stack and investigated the switching characteristics of RRAM devices with varying thicknesses and oxygen vacancy distributions across the trilayer to achieve reliable bulk switching without any filament formation. We demonstrated bulk switching operation at megaohm regime with high current nonlinearity and programmed up to 100 levels without compliance current. We developed a neuromorphic compute-in-memory platform based on trilayer bulk RRAM crossbars by combining energy-efficient switched-capacitor voltage sensing circuits with differential encoding of weights to experimentally demonstrate high-accuracy matrix-vector multiplication. We showcased the computational capability of bulk RRAM crossbars by implementing a spiking neural network model for an autonomous navigation/racing task. Our work addresses challenges posed by existing RRAM technologies and paves the way for neuromorphic computing at the edge under strict size, weight, and power constraints.
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- 2023
18. Precessing jet nozzle connecting to a spinning black hole in M87
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Cui, Yuzhu, Hada, Kazuhiro, Kawashima, Tomohisa, Kino, Motoki, Lin, Weikang, Mizuno, Yosuke, Ro, Hyunwook, Honma, Mareki, Yi, Kunwoo, Yu, Jintao, Park, Jongho, Jiang, Wu, Shen, Zhiqiang, Kravchenko, Evgeniya, Algaba, Juan-Carlos, Cheng, Xiaopeng, Cho, Ilje, Giovannini, Gabriele, Giroletti, Marcello, Jung, Taehyun, Lu, Ru-Sen, Niinuma, Kotaro, Oh, Junghwan, Ohsuga, Ken, Sawada-Satoh, Satoko, Sohn, Bong Won, Takahashi, Hiroyuki R., Takamura, Mieko, Tazaki, Fumie, Trippe, Sascha, Wajima, Kiyoaki, Akiyama, Kazunori, An, Tao, Asada, Keiichi, Buttaccio, Salvatore, Byun, Do-Young, Cui, Lang, Hagiwara, Yoshiaki, Hirota, Tomoya, Hodgson, Jeffrey, Kawaguchi, Noriyuki, Kim, Jae-Young, Lee, Sang-Sung, Lee, Jee Won, Lee, Jeong Ae, Maccaferri, Giuseppe, Melis, Andrea, Melnikov, Alexey, Migoni, Carlo, Oh, Se-Jin, Sugiyama, Koichiro, Wang, Xuezheng, Zhang, Yingkang, Chen, Zhong, Hwang, Ju-Yeon, Jung, Dong-Kyu, Kim, Hyo-Ryoung, Kim, Jeong-Sook, Kobayashi, Hideyuki, Li, Bin, Li, Guanghui, Li, Xiaofei, Liu, Zhiyong, Liu, Qinghui, Liu, Xiang, Oh, Chung-Sik, Oyama, Tomoaki, Roh, Duk-Gyoo, Wang, Jinqing, Wang, Na, Wang, Shiqiang, Xia, Bo, Yan, Hao, Yeom, Jae-Hwan, Yonekura, Yoshinori, Yuan, Jianping, Zhang, Hua, Zhao, Rongbing, and Zhong, Weiye
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Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Astrophysics of Galaxies - Abstract
The nearby radio galaxy M87 offers a unique opportunity to explore the connections between the central supermassive black hole and relativistic jets. Previous studies of the inner region of M87 revealed a wide opening angle for the jet originating near the black hole. The Event Horizon Telescope resolved the central radio source and found an asymmetric ring structure consistent with expectations from General Relativity. With a baseline of 17 years of observations, there was a shift in the jet's transverse position, possibly arising from an eight to ten-year quasi-periodicity. However, the origin of this sideways shift remains unclear. Here we report an analysis of radio observations over 22 years that suggests a period of about 11 years in the position angle variation of the jet. We infer that we are seeing a spinning black hole that induces the Lense-Thirring precession of a misaligned accretion disk. Similar jet precession may commonly occur in other active galactic nuclei but has been challenging to detect owing to the small magnitude and long period of the variation., Comment: 41 pages, 7 figures, 7 tables
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- 2023
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19. An SiO Toroid and Wide-angle Outflow associated with the Massive Protostar W75N(B)-VLA2
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Gomez, Jose F., Torrelles, Jose M., Girart, Josep M., Surcis, Gabriele, Kim, Jeong-Sook, Canto, Jorge, Anglada, Guillem, Curiel, Salvador, Vlemmings, Wouter H. T., Carrasco-Gonzalez, Carlos, Rodriguez-Kamenetzky, Adriana R., Kim, Soon-Wook, Goddi, Ciriaco, van Langevelde, Huib J., and Sanchez-Monge, Alvaro
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Astrophysics - Solar and Stellar Astrophysics ,Astrophysics - Astrophysics of Galaxies - Abstract
We have carried out ALMA observations of the massive star-forming region W75N(B), which contains the massive protostars VLA1, VLA2, and VLA3. Particularly, VLA2 is an enigmatic protostar associated with a wind-driven H$_2$O maser shell, which has evolved from an almost isotropic outflow to a collimated one in just 20 years. The shell expansion seemed to be halted by an obstacle located to the northeast of VLA2. Here we present our findings from observing the 1.3 mm continuum and H$_2$CO and SiO emission lines. Within a region of $\sim 30"$ ($\sim 39,000$ au) diameter, we have detected 40 compact mm-continuum sources, three of them coinciding with VLA1, VLA2, and VLA3. While the H$_2$CO emission is mainly distributed in a fragmented structure around the three massive protostars, but without any of the main H$_2$CO clumps spatially coinciding with them, the SiO is highly concentrated on VLA2, indicating the presence of very strong shocks generated near this protostar. The SiO emission is clearly resolved into an elongated structure ($\sim 0.6"\times0.3"$; $\sim 780$ au$\times$390 au) perpendicular to the major axis of the wind-driven maser shell. The structure and kinematics of the SiO emission are consistent with a toroid and a wide-angle outflow surrounding a central mass of $\sim 10$ M$_{\odot}$, thus supporting previous theoretical predictions regarding the evolution of the outflow. Additionally, we have identified the expected location and estimated the gas density of the obstacle that is hindering the expansion of the maser shell., Comment: To be published in The Astrophysical Journal Letters. Sixteen pages, seven figures. Updated metadata
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- 2023
20. Development of Comprehensive Personal Health Records Integrating Patient-Generated Health Data Directly From Samsung S-Health and Apple Health Apps: Retrospective Cross-Sectional Observational Study
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Jung, Se Young, Kim, Jeong-Whun, Hwang, Hee, Lee, Keehyuck, Baek, Rong-Min, Lee, Ho-Young, Yoo, Sooyoung, Song, Wongeun, and Han, Jong Soo
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Information technology ,T58.5-58.64 ,Public aspects of medicine ,RA1-1270 - Abstract
BackgroundPatient-generated health data (PGHD), especially lifelog data, are important for managing chronic diseases. Additionally, personal health records (PHRs) have been considered an effective tool to engage patients more actively in the management of their chronic diseases. However, no PHRs currently integrate PGHD directly from Samsung S-Health and Apple Health apps. ObjectiveThe purposes of this study were (1) to demonstrate the development of an electronic medical record (EMR)–tethered PHR system (Health4U) that integrates lifelog data from Samsung S-Health and Apple Health apps and (2) to explore the factors associated with the use rate of the functions. MethodsTo upgrade conventional EMR-tethered PHRs, a task-force team (TFT) defined the functions necessary for users. After implementing a new system, we enrolled adults aged 19 years and older with prior experience of accessing Health4U in the 7-month period after November 2017, when the service was upgraded. ResultsOf the 17,624 users, 215 (1.22%) integrated daily steps data, 175 (0.99%) integrated weight data, 51 (0.29%) integrated blood sugar data, and 90 (0.51%) integrated blood pressure data. Overall, 61.95% (10,919/17,624) had one or more chronic diseases. For integration of daily steps data, 48.3% (104/215) of patients used the Apple Health app, 43.3% (93/215) used the S-Health app, and 8.4% (18/215) entered data manually. To retrieve medical documentation, 324 (1.84%) users downloaded PDF files and 31 (0.18%) users integrated their medical records into the Samsung S-Health app via the Consolidated-Clinical Document Architecture download function. We found a consistent increase in the odds ratios for PDF downloads among patients with a higher number of chronic diseases. The age groups of ≥60 years and ≥80 years tended to use the download function less frequently than the others. ConclusionsThis is the first study to examine the factors related to integration of lifelog data from Samsung S-Health and Apple Health apps into EMR-tethered PHRs and factors related to the retrieval of medical documents from PHRs. Our findings on the lifelog data integration can be used to design PHRs as a platform to integrate lifelog data in the future.
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- 2019
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21. Impact of Personal Health Records and Wearables on Health Outcomes and Patient Response: Three-Arm Randomized Controlled Trial
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Kim, Jeong-Whun, Ryu, Borim, Cho, Seoyoon, Heo, Eunyoung, Kim, Yoojung, Lee, Joongseek, Jung, Se Young, and Yoo, Sooyoung
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Information technology ,T58.5-58.64 ,Public aspects of medicine ,RA1-1270 - Abstract
BackgroundAlthough using the technologies for a variety of chronic health conditions such as personal health record (PHR) is reported to be acceptable and useful, there is a lack of evidence on the associations between the use of the technologies and the change of health outcome and patients’ response to a digital health app. ObjectiveThis study aimed to examine the impact of the use of PHR and wearables on health outcome improvement and sustained use of the health app that can be associated with patient engagement. MethodsWe developed an Android-based mobile phone app and used a wristband-type activity tracker (Samsung Charm) to collect data on health-related daily activities from individual patients. Dietary record, daily step counts, sleep log, subjective stress amount, blood pressure, and weight values were recorded. We conducted a prospective randomized clinical trial across 4 weeks on those diagnosed with obstructive sleep apnea (OSA) who had visited the outpatient clinic of Seoul National University Bundang Hospital. The trial randomly assigned 60 patients to 3 subgroups including 2 intervention groups: (1) mobile app and wearable device users (n=20), (2) mobile app–only users (n=20), and (3) controls (n=20). The primary outcome measure was weight change. Body weights before and after the trial were recorded and analyzed during clinic visits. Changes in OSA–related respiratory parameters such as respiratory disturbance, apnea-hypopnea, and oxygenation desaturation indexes and snoring comprised the secondary outcome and were analyzed for each participant. ResultsWe collected the individual data for each group during the trial, specifically anthropometric measurement and laboratory test results for health outcomes, and the app usage logs for patient response were collected and analyzed. The body weight showed a significant reduction in the 2 intervention groups after intervention, and the mobile app–only group showed more weight loss compared with the controls (P=.01). There were no significant changes in sleep-related health outcomes. From a patient response point of view, the average daily step counts (8165 steps) from the app plus wearable group were significantly higher than those (6034 steps) from the app-only group because they collected step count data from different devices (P=.02). The average rate of data collection was not different in physical activity (P=.99), food intake (P=.98), sleep (P=.95), stress (P=.70), and weight (P=.90) in the app plus wearable and app-only groups, respectively. ConclusionsWe tried to integrate PHR data that allow clinicians and patients to share lifelog data with the clinical workflow to support lifestyle interventions. Our results suggest that a PHR–based intervention may be successful in losing body weight and improvement in lifestyle behavior. Trial RegistrationClinicalTrials.gov NCT03200223; https://clinicaltrials.gov/ct2/show/NCT03200223 (Archived by WebCite at http://www.webcitation.org/74baZmnCX).
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- 2019
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22. Preparation and characterization of ethylene-propylene-diene monomer rubber/metal hydroxide composites by electron beam irradiation
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Kim, Jeong-In, Lee, Byoung-Min, Kim, Hyun-Rae, Park, Jong-Seok, Jung, Seung-Tae, Nho, Young-Chang, Kim, Jaewoo, and Choi, Jae-Hak
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Fireproofing agents -- Mechanical properties ,Ethylene -- Mechanical properties ,Hydroxides -- Mechanical properties ,Propylene -- Mechanical properties ,Rubber -- Mechanical properties ,Engineering and manufacturing industries ,Science and technology - Abstract
Ethylene-propylene-diene monomer (EPDM) rubber has widespread uses in various applications due to its ozone and oxidation stability, weatherability, electrical insulation, and elasticity. However, its further use is limited by low flame retardancy and low thermal stability. This study incorporated metal hydroxide flame retardant to enhance flame retardancy and electron beam cross-linking to simultaneously enhance mechanical properties, thermal stability, and flame retardancy. The utilization of electron beam irradiation resulted in an increase in gel content and a decrease in swelling ratio with increasing absorbed doses, indicating the successful formation of cross-linked network structures. The hot-set elongation was significantly reduced to 0.6%-0.8%, while the decomposition temperature increased with increasing absorbed doses, indicating improved thermal stability. The results from limiting oxygen index measurements and burning tests demonstrate that the flame retardancy of EPDM was improved by the combined effect of metal hydroxide flame retardant and electron beam cross-linking. Highlights * EPDM/metal hydroxide composites were prepared via electron beam irradiation. * Metal hydroxide flame retardants were incorporated to enhance flame retardancy. * EBI simultaneously enhanced mechanical property and thermal stability. KEYWORDS cross-linking, electron beam irradiation, ethylene-propylene-diene monomer rubber, gel content, limiting oxygen index, mechanical property, thermal stability, 1 | INTRODUCTION Ethylene-propylene-diene-monomer (EPDM) rubber is a versatile synthetic rubber composed of ethylene, propylene, and a small amount of unsaturated dienes, such as ethylidene norbornene (ENB), dicyclopentadiene (DCPD), and [...]
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- 2024
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23. Mechanism of phase condensation for chromosome architecture and function
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Park, Jeongveen, Kim, Jeong-Jun, and Ryu, Je-Kyung
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- 2024
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24. Gravitational wave probes on self-interacting dark matter surrounding an intermediate mass black hole
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Kadota, Kenji, Kim, Jeong Han, Ko, Pyungwon, and Yang, Xing-Yu
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High Energy Physics - Phenomenology ,Astrophysics - Cosmology and Nongalactic Astrophysics ,General Relativity and Quantum Cosmology ,High Energy Physics - Theory - Abstract
The presence of dark matter overdensities surrounding a black hole can influence the evolution of a binary system. The gravitational wave signals emitted by a black hole binary offer a promising means to probe the dark matter environments near a black hole. The dense region of dark matter can lead to the dephasing of gravitational waveforms, which can be detected by upcoming experiments such as the Laser Interferometer Space Antenna (LISA). The dark matter density profile around the black hole can vary for different dark matter models. Our study specifically investigates the impact of the ultralight self-interacting scalar dark matter (SIDM) on the gravitational wave signals emitted by black hole binaries. A distinctive characteristic of SIDM surrounding a black hole, as opposed to collisionless dark matter, is the formation of a soliton core. We perform a Fisher matrix analysis to estimate the size of the soliton and the corresponding SIDM parameter space that future LISA-like gravitational wave experiments can explore., Comment: 12 pages, 7 figures, 1 table; matches the published version
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- 2023
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25. Influence of Surface Contaminants and Hydrocarbon Pellicle on the Results of Wettability Measurements of Titanium.
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Cheng, James, Kim, Jeong, Park, Wonhee, Ogawa, Takahiro, Kido, Daisuke, Komatsu, Keiji, Suzumura, Toshikatsu, and Matsuura, Takanori
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UV photofunctionalization ,bone integration ,osseointegration ,titanium implants ,wettability - Abstract
Hydrophilicity/hydrophobicity-or wettability-is a key surface characterization metric for titanium used in dental and orthopedic implants. However, the effects of hydrophilicity/hydrophobicity on biological capability remain uncertain, and the relationships between surface wettability and other surface parameters, such as topography and chemistry, are poorly understood. The objective of this study was to identify determinants of surface wettability of titanium and establish the reliability and validity of the assessment. Wettability was evaluated as the contact angle of ddH2O. The age of titanium specimens significantly affected the contact angle, with acid-etched, microrough titanium surfaces becoming superhydrophilic immediately after surface processing, hydrophobic after 7 days, and hydrorepellent after 90 days. Similar age-related loss of hydrophilicity was also confirmed on sandblasted supra-micron rough surfaces so, regardless of surface topography, titanium surfaces eventually become hydrophobic or hydrorepellent with time. On age-standardized titanium, surface roughness increased the contact angle and hydrophobicity. UV treatment of titanium regenerated the superhydrophilicity regardless of age or surface roughness, with rougher surfaces becoming more superhydrophilic than machined surfaces after UV treatment. Conditioning titanium surfaces by autoclaving increased the hydrophobicity of already-hydrophobic surfaces, whereas conditioning with 70% alcohol and hydrating with water or saline attenuated pre-existing hydrophobicity. Conversely, when titanium surfaces were superhydrophilic like UV-treated ones, autoclaving and alcohol cleaning turned the surfaces hydrorepellent and hydrophobic, respectively. UV treatment recovered hydrophilicity without exception. In conclusion, surface roughness accentuates existing wettability and can either increase or decrease the contact angle. Titanium must be age-standardized when evaluating surface wettability. Surface conditioning techniques significantly but unpredictably affect existing wettability. These implied that titanium wettability is significantly influenced by the hydrocarbon pellicle and other contaminants inevitably accumulated. UV treatment may be an effective strategy to standardize wettability by making all titanium surfaces superhydrophilic, thereby allowing the characterization of individual surface topography and chemistry parameters in future studies.
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- 2023
26. Usage Pattern Differences and Similarities of Mobile Electronic Medical Records Among Health Care Providers
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Lee, Yura, Park, Yu Rang, Kim, Junetae, Kim, Jeong Hoon, Kim, Woo Sung, and Lee, Jae-Ho
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Information technology ,T58.5-58.64 ,Public aspects of medicine ,RA1-1270 - Abstract
BackgroundRecently, many hospitals have introduced mobile electronic medical records (mEMRs). Although numerous studies have been published on the usability or usage patterns of mEMRs through user surveys, investigations based on the real data usage are lacking. ObjectiveAsan Medical Center, a tertiary hospital in Seoul, Korea, implemented an mEMR program in 2010. On the basis of the mEMR usage log data collected over a period of 4.5 years, we aimed to identify a usage pattern and trends in accordance with user occupation and to disseminate the factors that make the mEMR more effective and efficient. MethodsThe mEMR log data were collected from March 2012 to August 2016. Descriptive analyses were completed according to user occupation, access time, services, and wireless network type. Specifically, analyses targeted were as follows: (1) the status of the mEMR usage and distribution of users, (2) trends in the number of users and usage amount, (3) 24-hour usage patterns, and (4) trends in service usage based on user occupations. Linear regressions were performed to model the relationship between the time, access frequency, and the number of users. The differences between the user occupations were examined using Student t tests for categorical variables. ResultsApproximately two-thirds of the doctors and nurses used the mEMR. The number of logs studied was 7,144,459. Among 3859 users, 2333 (60.46%) users were nurses and 1102 (28.56%) users were doctors. On average, the mEMR was used 1044 times by 438 users per day. The number of users and amount of access logs have significantly increased since 2012 (P
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- 2017
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27. Implementation of chemistry in the Athena++ code
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Gong, Munan, Ho, Ka-Wai, Stone, James M., Ostriker, Eve C., Caselli, Paola, Grassi, Tommaso, Kim, Chang-Goo, Kim, Jeong-Gyu, and Halevi, Goni
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Astrophysics - Astrophysics of Galaxies ,Astrophysics - Earth and Planetary Astrophysics ,Astrophysics - Instrumentation and Methods for Astrophysics ,Astrophysics - Solar and Stellar Astrophysics - Abstract
Chemistry plays a key role in many aspects of astrophysical fluids. Atoms and molecules are agents for heating and cooling, determine the ionization fraction, serve as observational tracers, and build the molecular foundation of life. We present the implementation of a chemistry module in the publicly available magneto-hydrodynamic code Athena++. We implement several chemical networks and heating and cooling processes suitable for simulating the interstellar medium (ISM). A general chemical network framework in the KIDA format is also included, allowing the user to easily implement their own chemistry. Radiation transfer and cosmic-ray ionization are coupled with chemistry and solved with the simple six-ray approximation. The chemical and thermal processes are evolved as a system of coupled ODEs with an implicit solver from the CVODE library. We perform and present a series of tests to ensure the numerical accuracy and convergence of the code. Many tests combine chemistry with gas dynamics, including comparisons with analytic solutions, 1D problems of the photo-dissociation regions and shocks, and realistic 3D simulations of the turbulent ISM. We release the code with the new public version of Athena++, aiming to provide a robust and flexible code for the astrochemical simulation community.
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- 2023
28. Uncovering doubly charged scalars with dominant three-body decays using machine learning
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Flacke, Thomas, Kim, Jeong Han, Kunkel, Manuel, Ko, Pyungwon, Pi, Jun Seung, Porod, Werner, and Schwarze, Leonard
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High Energy Physics - Phenomenology ,High Energy Physics - Experiment - Abstract
We propose a deep learning-based search strategy for pair production of doubly charged scalars undergoing three-body decays to $W^+ t\bar b$ in the same-sign lepton plus multi-jet final state. This process is motivated by composite Higgs models with an underlying fermionic UV theory. We demonstrate that for such busy final states, jet image classification with convolutional neural networks outperforms standard fully connected networks acting on reconstructed kinematic variables. We derive the expected discovery reach and exclusion limit at the high-luminosity LHC., Comment: 16 pages, 14 figures, 2 technical appendices
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- 2023
29. An $\text{SL}(3,\mathbb{C})$-equivariant smooth compactification of rational quartic plane curves
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Chung, Kiryong and Kim, Jeong-Seop
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Mathematics - Algebraic Geometry - Abstract
Let $\mathbf{R}_d$ be the space of stable sheaves $F$ which satisfy the Hilbert polynomial $\chi(F(m))=dm+1$ and are supported on rational curves in the projective plane $\mathbb{P}^2$. Then $\mathbf{R}_1$ (resp. $\mathbf{R}_2$) is isomorphic to $\mathbf{R}_1\cong\mathbb{P}^2$ (resp. $\mathbf{R}_2\cong \mathbb{P}^5$). Also it is very well-known that $\mathbf{R}_3$ is isomorphic to a $\mathbb{P}^6$-bundle over $\mathbb{P}^2$. In special $\mathbf{R}_d$ is smooth for $d\leq 3$. But for $d\geq4$ case, one can imagine that the space $\mathbf{R}_d$ is no more smooth because of the complexity of boundary curves. In this paper, we obtain an $\mathrm{SL}(3,\mathbb{C})$-equivariant smooth resolution of $\mathbf{R}_4$ for $d=4$, which is a $\mathbb{P}^5$-bundle over the blow-up of a Kronecker modules space., Comment: Comments are welcome
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- 2023
30. Probing Cosmological Particle Production and Pairwise Hotspots with Deep Neural Networks
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Kim, Taegyun, Kim, Jeong Han, Kumar, Soubhik, Martin, Adam, Münchmeyer, Moritz, and Tsai, Yuhsin
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High Energy Physics - Phenomenology ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
Particles with masses much larger than the inflationary Hubble scale, $H_I$, can be pair-produced non-adiabatically during inflation. Due to their large masses, the produced particles modify the curvature perturbation around their locations. These localized perturbations eventually give rise to localized signatures on the Cosmic Microwave Background (CMB), in particular, pairwise hotspots (PHS). In this work, we show that Convolutional Neural Networks (CNN) provide a powerful tool for identifying PHS on the CMB. While for a given hotspot profile a traditional Matched Filter Analysis is known to be optimal, a Neural Network learns to effectively detect the large variety of shapes that can arise in realistic models of particle production. Considering an idealized situation where the dominant background to the PHS signal comes from the standard CMB fluctuations, we show that a CNN can isolate the PHS with $\mathcal{O}(10)\%$ efficiency even if the hotspot temperature is $\mathcal{O}(10)$ times smaller than the average CMB fluctuations. Overall, the CNN search is sensitive to heavy particle masses $M_0/H_I=\mathcal{O}(200)$, and constitutes one of the unique probes of very high energy particle physics.
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- 2023
31. Spectral analysis of a parsec-scale jet in M87: Observational constraint on the magnetic field strengths in the jet
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Ro, Hyunwook, Kino, Motoki, Sohn, Bong Won, Hada, Kazuhiro, Park, Jongho, Nakamura, Masanori, Cui, Yuzhu, Yi, Kunwoo, Chung, Aeree, Hodgson, Jeffrey, Kawashima, Tomohisa, An, Tao, Trippe, Sascha, Algaba, Juan-Carlos, Kim, Jae-Young, Sawada-Satoh, Satoko, Wajima, Kiyoaki, Shen, Zhiqiang, Cheng, Xiaopeng, Cho, Ilje, Jiang, Wu, Jung, Taehyun, Lee, Jee-Won, Niinuma, Kotaro, Oh, Junghwan, Tazaki, Fumie, Zhao, Guang-Yao, Akiyama, Kazunori, Honma, Mareki, Lee, Jeong Ae, Lu, Rusen, Zhang, Yingkang, Asada, Keiichi, Cui, Lang, Hagiwara, Yoshiaki, Hirota, Tomoya, Kawaguchi, Noriyuki, Koyama, Shoko, Lee, Sang-Sung, Oh, Se-Jin, Sugiyama, Koichiro, Takamura, Mieko, Wang, Xuezheng, Hwang, Ju-Yeon, Jung, Dong-Kyu, Kim, Hyo-Ryoung, Kim, Jeong-Sook, Kobayashi, Hideyuki, Oh, Chung-Sik, Oyama, Tomoaki, Roh, Duk-Gyoo, and Yeom, Jae-Hwan
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Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
Because of its proximity and the large size of its black hole, M87 is one of the best targets for studying the launching mechanism of active galactic nucleus jets. Currently, magnetic fields are considered to be an essential factor in the launching and accelerating of the jet. However, current observational estimates of the magnetic field strength of the M87 jet are limited to the innermost part of the jet or to HST-1. No attempt has yet been made to measure the magnetic field strength in between. We aim to infer the magnetic field strength of the M87 jet out to a distance of several thousand $r_s$ by tracking the distance-dependent changes in the synchrotron spectrum of the jet from high-resolution very long baseline interferometry observations. In order to obtain high-quality spectral index maps, quasi-simultaneous observations at 22 and 43 GHz were conducted using the KVN and VERA Array (KaVA) and the VLBA. We compared the spectral index distributions obtained from the observations with a model and placed limits on the magnetic field strengths as a function of distance. The overall spectral morphology is broadly consistent over the course of these observations. The observed synchrotron spectrum rapidly steepens from $\alpha_{22-43 GHz}$ ~ -0.7 at ~ 2 mas to $\alpha_{22-43 GHz}$ ~ -2.5 at ~ 6 mas. A spectral index model in which nonthermal electron injections inside the jet decrease with distance can adequately reproduce the observed trend. This suggests the magnetic field strength of the jet at a distance of 2 - 10 mas (~ 900 $r_s$ - ~ 4500 $r_s$ in the deprojected distance) has a range of $B=(0.3 - 1.0 G)(z/2 mas)^{-0.73}$. Extrapolating to the EHT scale yields consistent results, suggesting that the majority of the magnetic flux of the jet near the black hole is preserved out to ~ 4500 $r_s$ without significant dissipation., Comment: 16 pages, 9 figures. Accepted for publication in Astronomy & Astrophysics
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- 2023
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32. Entanglement witness and multipartite quantum state discrimination
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Ha, Donghoon and Kim, Jeong San
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Quantum Physics - Abstract
We consider multipartite quantum state discrimination and show that the minimum-error discrimination by separable measurements is closely related to the concept of entanglement witness. Based on the properties of entanglement witness, we establish some necessary and/or sufficient conditions on minimum-error discrimination by separable measurements. We also provide some conditions on the upper bound of the maximum success probability over all possible separable measurements. Our results are illustrated by examples of multidimensional multipartite quantum states. Finally, we provide a systematic way in terms of the entanglement witness to construct multipartite quantum state ensembles showing nonlocality in state discrimination., Comment: 13 pages, 1 figure. arXiv admin note: substantial text overlap with arXiv:2212.10799
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- 2023
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33. Bipartite quantum state discrimination and decomposable entanglement witness
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Ha, Donghoon and Kim, Jeong San
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Quantum Physics - Abstract
We consider bipartite quantum state discrimination using positive-partial-transpose measurements and show that minimum-error discrimination by positive-partial-transpose measurements is closely related to entanglement witness. By using the concept of decomposable entanglement witness, we establish conditions on minimum-error discrimination by positive-partial-transpose measurements. We also provide conditions on the upper bound of the maximum success probability over all possible positive-partial-transpose measurements. Finally, we illustrate our results using examples of multidimensional bipartite quantum states., Comment: 14 pages, 1 figure
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- 2022
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34. Overview of the Observing System and Initial Scientific Accomplishments of the East Asian VLBI Network (EAVN)
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Akiyama, Kazunori, Algaba, Juan-Carlos, An, Tao, Asada, Keiichi, Asanok, Kitiyanee, Byun, Do-Young, Chanapote, Thanapol, Chen, Wen, Chen, Zhong, Cheng, Xiaopeng, Chibueze, James O., Cho, Ilje, Cho, Se-Hyung, Chung, Hyun-Soo, Cui, Lang, Cui, Yuzhu, Doi, Akihiro, Dong, Jian, Fujisawa, Kenta, Gou, Wei, Guo, Wen, Hada, Kazuhiro, Hagiwara, Yoshiaki, Hirota, Tomoya, Hodgson, Jeffrey A., Honma, Mareki, Imai, Hiroshi, Jaroenjittichai, Phrudth, Jiang, Wu, Jiang, Yongbin, Jiang, Yongchen, Jike, Takaaki, Jung, Dong-Kyu, Jung, Taehyun, Kawaguchi, Noriyuki, Kim, Dong-Jin, Kim, Hyo-Ryoung, Kim, Jaeheon, Kim, Jeong-Sook, Kim, Kee-Tae, Kim, Soon-Wook, Kino, Motoki, Kobayashi, Hideyuki, Koyama, Shoko, Kramer, Busaba H., Lee, Jee-Won, Lee, Jeong Ae, Lee, Sang-Sung, Lee, Sang Won, Li, Bin, Li, Guanghui, Li, Xiaofei, Li, Zhixuan, Liu, Qinghui, Liu, Xiang, Lu, Ru-Sen, Motogi, Kazuhito, Nakamura, Masanori, Niinuma, Kotaro, Oh, Chungsik, Oh, Hongjong, Oh, Junghwan, Oh, Se-Jin, Oyama, Tomoaki, Park, Jongho, Poshyachinda, Saran, Ro, Hyunwook, Roh, Duk-Gyoo, Rujopakarn, Wiphu, Sakai, Nobuyuki, Sawada-Satoh, Satoko, Shen, Zhi-Qiang, Shibata, Katsunori M., Sohn, Bong Won, Soonthornthum, Boonrucksar, Sugiyama, Koichiro, Sun, Yunxia, Takamura, Mieko, Tanabe, Yoshihiro, Tazaki, Fumie, Trippe, Sascha, Wajima, Kiyoaki, Wang, Jinqing, Wang, Na, Wang, Shiqiang, Wang, Xuezheng, Xia, Bo, Xu, Shuangjing, Yan, Hao, Yang, Wenjun, Yeom, Jae-Hwan, Yi, Kunwoo, Yi, Sang-Oh, Yonekura, Yoshinori, Yoon, Hasu, Yu, Linfeng, Yuan, Jianping, Yun, Youngjoo, Zhang, Bo, Zhang, Hua, Zhang, Yingkang, Zhao, Guang-Yao, Zhao, Rongbing, and Zhong, Weiye
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Astrophysics - Instrumentation and Methods for Astrophysics - Abstract
The East Asian VLBI Network (EAVN) is an international VLBI facility in East Asia and is operated under mutual collaboration between East Asian countries, as well as part of Southeast Asian and European countries. EAVN currently consists of 16 radio telescopes and three correlators located in China, Japan, and Korea, and is operated mainly at three frequency bands, 6.7, 22, and 43 GHz with the longest baseline length of 5078 km, resulting in the highest angular resolution of 0.28 milliarcseconds at 43 GHz. One of distinct capabilities of EAVN is multi-frequency simultaneous data reception at nine telescopes, which enable us to employ the frequency phase transfer technique to obtain better sensitivity at higher observing frequencies. EAVN started its open-use program in the second half of 2018, providing a total observing time of more than 1100 hours in a year. EAVN fills geographical gap in global VLBI array, resulting in enabling us to conduct contiguous high-resolution VLBI observations. EAVN has produced various scientific accomplishments especially in observations toward active galactic nuclei, evolved stars, and star-forming regions. These activities motivate us to initiate launch of the 'Global VLBI Alliance' to provide an opportunity of VLBI observation with the longest baselines on the earth., Comment: 27 pages, appeared in Galaxies special issue 'Challenges in Understanding Black Hole Powered Jets with VLBI' as an invited review
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- 2022
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35. Development of a Weight Loss Mobile App Linked With an Accelerometer for Use in the Clinic: Usability, Acceptability, and Early Testing of its Impact on the Patient-Doctor Relationship
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Choo, Seryung, Kim, Ju Young, Jung, Se Young, Kim, Sarah, Kim, Jeong Eun, Han, Jong Soo, Kim, Sohye, Kim, Jeong Hyun, Kim, Jeehye, Kim, Yongseok, Kim, Dongouk, and Steinhubl, Steve
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Information technology ,T58.5-58.64 ,Public aspects of medicine ,RA1-1270 - Abstract
BackgroundAlthough complications of obesity are well acknowledged and managed by clinicians, management of obesity itself is often difficult, which leads to its underdiagnosis and undertreatment in hospital settings. However, tools that could improve the management of obesity, including self-monitoring, engagement with a social network, and open channels of communication between the patient and doctor, are limited in a clinic-based setting. ObjectiveThe objective of our study was to evaluate the usability and acceptability of a newly developed mobile app linked with an accelerometer and its early effects on patient-doctor relationships. MethodsFrom September 2013 to February 2014, we developed a mobile app linked with an accelerometer as a supportive tool for a clinic-based weight loss program. The app used information from electronic health records and delivered tailored educational material. Personal goal setting, as well as monitoring of weight changes and physical activity combined with feedback, are key features of the app. We also incorporated an interactive message board for patients and doctors. During the period of March 2014 to May 2014, we tested our mobile app for 1 month in participants in a hospital clinic setting. We assessed the app’s usability and acceptability, as well as the patient-doctor relationship, via questionnaires and analysis of app usage data. ResultsWe recruited 30 individuals (18 male and 12 female) for the study. The median number of log-ins per day was 1.21, with the most frequently requested item being setting goals, followed by track physical activities and view personal health status. Scales of the depth of the patient-doctor relationship decreased from 27.6 (SD 4.8) to 25.1 (SD 4.5) by a Wilcoxon signed rank test (P=.02). ConclusionsA mobile phone app linked with an accelerometer for a clinic-based weight loss program is useful and acceptable for weight management but exhibited less favorable early effects on patient-doctor relationships.
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- 2016
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36. Sensory specializations drive octopus and squid behaviour.
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Kang, Guipeun, Allard, Corey, Valencia-Montoya, Wendy, van Giesen, Lena, Kim, Jeong, Kilian, Peter, Bai, Xiaochen, Bellono, Nicholas, and Hibbs, Ryan
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Animals ,Behavior ,Animal ,Binding Sites ,Cryoelectron Microscopy ,Decapodiformes ,Evolution ,Molecular ,Hydrophobic and Hydrophilic Interactions ,Neurotransmitter Agents ,Octopodiformes ,Receptors ,Nicotinic ,Taste ,Touch ,Sensory Receptor Cells - Abstract
The evolution of new traits enables expansion into new ecological and behavioural niches. Nonetheless, demonstrated connections between divergence in protein structure, function and lineage-specific behaviours remain rare. Here we show that both octopus and squid use cephalopod-specific chemotactile receptors (CRs) to sense their respective marine environments, but structural adaptations in these receptors support the sensation of specific molecules suited to distinct physiological roles. We find that squid express ancient CRs that more closely resemble related nicotinic acetylcholine receptors, whereas octopuses exhibit a more recent expansion in CRs consistent with their elaborated taste by touch sensory system. Using a combination of genetic profiling, physiology and behavioural analyses, we identify the founding member of squid CRs that detects soluble bitter molecules that are relevant in ambush predation. We present the cryo-electron microscopy structure of a squid CR and compare this with octopus CRs1 and nicotinic receptors2. These analyses demonstrate an evolutionary transition from an ancestral aromatic cage that coordinates soluble neurotransmitters or tastants to a more recent octopus CR hydrophobic binding pocket that traps insoluble molecules to mediate contact-dependent chemosensation. Thus, our study provides a foundation for understanding how adaptation of protein structure drives the diversification of organismal traits and behaviour.
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- 2023
37. Structural basis of sensory receptor evolution in octopus.
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Bellono, Nicholas, Allard, Corey, Kang, Guipeun, Kim, Jeong, Valencia-Montoya, Wendy, and Hibbs, Ryan
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Animals ,Cryoelectron Microscopy ,Ligands ,Octopodiformes ,Receptors ,Nicotinic ,Sensory Receptor Cells ,Touch ,Evolution ,Molecular ,Synaptic Transmission ,Binding Sites ,Hydrophobic and Hydrophilic Interactions - Abstract
Chemotactile receptors (CRs) are a cephalopod-specific innovation that allow octopuses to explore the seafloor via taste by touch1. CRs diverged from nicotinic acetylcholine receptors to mediate contact-dependent chemosensation of insoluble molecules that do not readily diffuse in marine environments. Here we exploit octopus CRs to probe the structural basis of sensory receptor evolution. We present the cryo-electron microscopy structure of an octopus CR and compare it with nicotinic receptors to determine features that enable environmental sensation versus neurotransmission. Evolutionary, structural and biophysical analyses show that the channel architecture involved in cation permeation and signal transduction is conserved. By contrast, the orthosteric ligand-binding site is subject to diversifying selection, thereby mediating the detection of new molecules. Serendipitous findings in the cryo-electron microscopy structure reveal that the octopus CR ligand-binding pocket is exceptionally hydrophobic, enabling sensation of greasy compounds versus the small polar molecules detected by canonical neurotransmitter receptors. These discoveries provide a structural framework for understanding connections between evolutionary adaptations at the atomic level and the emergence of new organismal behaviour.
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- 2023
38. Introducing TIGRESS-NCR: I. Co-Regulation of the Multiphase Interstellar Medium and Star Formation Rates
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Kim, Chang-Goo, Kim, Jeong-Gyu, Gong, Munan, and Ostriker, Eve C.
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Astrophysics - Astrophysics of Galaxies - Abstract
Massive, young stars are the main source of energy that maintains multiphase structure and turbulence in the interstellar medium (ISM), and without this "feedback" the star formation rate (SFR) would be much higher than is observed. Rapid energy loss in the ISM and efficient energy recovery by stellar feedback lead to co-regulation of SFRs and the ISM state. Realistic approaches to this problem should solve the dynamical evolution of the ISM, including star formation, and the input of feedback energy self-consistently and accurately. Here, we present the TIGRESS-NCR numerical framework, in which UV radiation, supernovae, cooling and heating processes, and gravitational collapse are modeled explicitly. We use an adaptive ray tracing method for UV radiation transfer from star clusters represented by sink particles, accounting for attenuation by dust and gas. We solve photon-driven chemical equations to determine the abundances of H (time-dependent) and C/O-bearing species (steady-state), which then set cooling and heating rates self-consistently. Applying these methods, we present high-resolution magnetohydrodynamics simulations of differentially rotating local galactic disks representing typical conditions of nearby star-forming galaxies. We analyze ISM properties and phase distributions and show good agreement with existing multiwavelength galactic observations. We measure midplane pressure components (turbulent, thermal, and magnetic) and the weight, demonstrating that vertical dynamical equilibrium holds. We quantify the ratios of pressure components to the SFR surface density, which we call the feedback yields. The TIGRESS-NCR framework will allow for a wide range of parameter exploration, including low metallicity system., Comment: ApJ accepted
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- 2022
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39. EAVN Astrometry toward the Extreme Outer Galaxy: Kinematic distance with the proper motion of G034.84-00.95
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Sakai, Nobuyuki, Zhang, Bo, Xu, Shuangjing, Sakai, Daisuke, Tamura, Yoshiaki, Jike, Takaaki, Jung, Taehyun, Oh, Chungsik, Kim, Jeong-Sook, Kawaguchi, Noriyuki, Imai, Hiroshi, Jiang, Wu, Cui, Lang, Kim, Soon-Wook, Jiang, Pengfei, Kurayama, Tomoharu, Lee, Jeong Ae, Hachisuka, Kazuya, Jung, Dong-Kyu, Xia, Bo, Li, Guanghui, Honma, Mareki, Kim, Kee-Tae, Shen, Zhi-Qiang, and Wang, Na
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Astrophysics - Astrophysics of Galaxies - Abstract
We aim to reveal the structure and kinematics of the Outer-Scutum-Centaurus (OSC) arm located on the far side of the Milky Way through very long baseline interferometry (VLBI) astrometry using KaVA, which is composed of KVN (Korean VLBI Network) and VERA (VLBI Exploration of Radio Astrometry). We report the proper motion of a 22 GHz H$_{2}$O maser source, which is associated with the star-forming region G034.84$-$00.95, to be ($\mu_{\alpha} \rm{cos}\delta$, $\mu_{\delta}$) = ($-$1.61$\pm$0.18, $-$4.29$\pm$0.16) mas yr$^{-1}$ in equatorial coordinates (J2000). We estimate the 2D kinematic distance to the source to be 18.6$\pm$1.0 kpc, which is derived from the variance-weighted average of kinematic distances with LSR velocity and the Galactic-longitude component of the measured proper motion. Our result places the source in the OSC arm and implies that G034.84$-$00.95 is moving away from the Galactic plane with a vertical velocity of $-$38$\pm$16 km s$^{-1}$. Since the H I supershell GS033+06$-$49 is located at a kinematic distance roughly equal to that of G034.84$-$00.95, it is expected that gas circulation occurs between the outer Galactic disk around G034.84$-$00.95 with a Galactocentric distance of 12.8$^{+1.0}_{-0.9}$ kpc and halo. We evaluate possible origins of the fast vertical motion of G034.84$-$00.95, which are (1) supernova explosions and (2) cloud collisions with the Galactic disk. However, neither of the possibilities are matched with the results of VLBI astrometry as well as spatial distributions of H II regions and H I gas., Comment: Accepted for publication in PASJ. 14 figures; 8 tables
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- 2022
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40. Photochemistry and Heating/Cooling of the Multiphase Interstellar Medium with UV Radiative Transfer for Magnetohydrodynamic Simulations
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Kim, Jeong-Gyu, Gong, Munan, Kim, Chang-Goo, and Ostriker, Eve C.
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Astrophysics - Astrophysics of Galaxies ,Astrophysics - Instrumentation and Methods for Astrophysics - Abstract
We present an efficient heating/cooling method coupled with chemistry and ultraviolet (UV) radiative transfer, which can be applied to numerical simulations of the interstellar medium (ISM). We follow the time-dependent evolution of hydrogen species (H$_2$, H, H$^+$), assume carbon/oxygen species (C, C$^+$, CO, O, and O$^+$) are in formation-destruction balance given the non-steady hydrogen abundances, and include essential heating/cooling processes needed to capture thermodynamics of all ISM phases. UV radiation from discrete point sources and the diffuse background is followed through adaptive ray tracing and a six-ray approximation, respectively, allowing for H$_2$ self-shielding; cosmic ray (CR) heating and ionization are also included. To validate our methods and demonstrate their application for a range of density, metallicity, and radiation field, we conduct a series of tests, including the equilibrium curves of thermal pressure vs. density, the chemical and thermal structure in photo-dissociation regions, H I-to-H$_2$ transitions, and the expansion of H II regions and radiative supernova remnants. Careful treatment of photochemistry and CR ionization is essential for many aspects of ISM physics, including identifying the thermal pressure at which cold and warm neutral phases co-exist. We caution that many current heating and cooling treatments used in galaxy formation simulations do not reproduce the correct thermal pressure and ionization fraction in the neutral ISM. Our new model is implemented in the MHD code Athena and incorporated in the TIGRESS simulation framework, for use in studying the star-forming ISM in a wide range of environments., Comment: 57 pages, 22 figures; accepted for publication in ApJS
- Published
- 2022
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41. Tuning orbital-selective phase transitions in a two-dimensional Hund's correlated system
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Ko, Eun Kyo, Hahn, Sungsoo, Sohn, Changhee, Lee, Sangmin, Lee, Seung-Sup B., Sohn, Byungmin, Kim, Jeong Rae, Son, Jaeseok, Song, Jeongkeun, Kim, Youngdo, Kim, Donghan, Kim, Miyoung, Kim, Choong H., Kim, Changyoung, and Noh, Tae Won
- Subjects
Condensed Matter - Strongly Correlated Electrons ,Condensed Matter - Materials Science - Abstract
Hund's rule coupling ($\textit{J}$) has attracted much attention recently for its role in the description of the novel quantum phases of multi orbital materials. Depending on the orbital occupancy, $\textit{J}$ can lead to various intriguing phases. However, experimental confirmation of the orbital occupancy dependency has been difficult as controlling the orbital degrees of freedom normally accompanies chemical inhomogeneities. Here, we demonstrate a method to investigate the role of orbital occupancy in $\textit{J}$ related phenomena without inducing inhomogeneities. By growing SrRuO$_3$ monolayers on various substrates with symmetry-preserving interlayers, we gradually tune the crystal field splitting and thus the orbital degeneracy of the Ru $\textit{t$_2$$_g$}$ orbitals. It effectively varies the orbital occupancies of two-dimensional (2D) ruthenates. Via in-situ angle-resolved photoemission spectroscopy, we observe a progressive metal-insulator transition (MIT). It is found that the MIT occurs with orbital differentiation: concurrent opening of a band insulating gap in the $\textit{d$_x$$_y$}$ band and a Mott gap in the $\textit{d$_x$$_z$$_/$$_y$$_z$}$ bands. Our study provides an effective experimental method for investigation of orbital-selective phenomena in multi-orbital materials.
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- 2022
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42. A Design Method of Distributed Algorithms via Discrete-time Blended Dynamics Theorem
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Kim, Jeong Woo, Lee, Jin Gyu, Lee, Donggil, and Shim, Hyungbo
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Electrical Engineering and Systems Science - Systems and Control - Abstract
We develop a discrete-time version of the blended dynamics theorem for the use of designing distributed computation algorithms. The blended dynamics theorem enables to predict the behavior of heterogeneous multi-agent systems. Therefore, once we get a blended dynamics for a particular computational task, design idea of node dynamics for individual heterogeneous agents can easily occur. In the continuous-time case, prediction by blended dynamics was enabled by high coupling gain among neighboring agents. In the discrete-time case, we propose an equivalent action, which we call multi-step coupling in this paper. Compared to the continuous-time case, the blended dynamics can have more variety depending on the coupling matrix. This benefit is demonstrated with three applications; distributed estimation of network size, distributed computation of the PageRank, and distributed computation of the degree sequence of a graph, which correspond to the coupling by doubly-stochastic, column-stochastic, and row-stochastic matrices, respectively.
- Published
- 2022
43. Physical Modeling of Dust Polarization from Magnetically Enhanced Radiative Torque (MRAT) Alignment in Protostellar Cores with POLARIS
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Giang, Nguyen Chau, Hoang, Thiem, Kim, Jeong-Gyu, and Tram, Le Ngoc
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Astrophysics - Astrophysics of Galaxies - Abstract
Magnetic fields ($\textbf{B}$) are an important factor that controls the star formation process. The leading method to observe $\textbf{B}$ is using polarized thermal emission from dust grains aligned with $\textbf{B}$. However, in dense environments such as protostellar cores, dust grains may have inefficient alignment due to strong gas randomizations, so that using dust polarization to trace $\textbf{B}$ is uncertain. Hoang $\&$ Lazarian (2016) demonstrated that the grain alignment by RAdiative Torques is enhanced if dust grains contain embedded iron inclusions. Here we extend POLARIS code to study the effect of iron inclusions on grain alignment and thermal dust polarization toward a protostellar core, assuming uniform magnetic fields. We found that paramagnetic grains produce a low polarization degree of $p \sim 1\%$ in the envelope and negligible $p \ll 1\%$ in the central region due to the loss of grain alignment. In contrast, grains with a high level of iron inclusions can have perfect alignment and produce high $p \sim 40\%$ in the envelope and low $p \leq 10\%$ in the central region. Grains with a moderate level of iron inclusions induce the polarization flipping from $\textbf{P}$ $\parallel$ $\textbf{B}$ at millimeter to $\textbf{P}$ $\perp$ $\textbf{B}$ at submillimeter due to the change in the internal alignment caused by slow internal relaxation. The weak alignment of very large grains of $a \geq 10\mu m$ reduces the polarization by dichroic extinction at submillimeter wavelengths. We found a positive correlation between p and the level of iron inclusions, which opens a new window to constrain the abundance of irons locked in dust through dust polarimetry., Comment: 39 pages, 27 figures
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- 2022
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44. Mr. Oh
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Kim, Jeong Mee
- Published
- 2001
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45. Balanced Encoding of Near-Zero Correlation for an AES Implementation
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Lee, Seungkwang and Kim, Jeong-Nyeo
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Computer Science - Cryptography and Security - Abstract
Power analysis poses a significant threat to the security of cryptographic algorithms, as it can be leveraged to recover secret keys. While various software-based countermeasures exist to mitigate this non-invasive attack, they often involve a trade-off between time and space constraints. Techniques such as masking and shuffling, while effective, can noticeably impact execution speed and rely heavily on run-time random number generators. On the contrary, internally encoded implementations of block ciphers offer an alternative approach that does not rely on run-time random sources, but it comes with the drawback of requiring substantial memory space to accommodate lookup tables. Internal encoding, commonly employed in white-box cryptography, suffers from a significant security limitation as it does not effectively protect the secret key against statistical analysis. To overcome this weakness, this paper introduces a secure internal encoding method for an AES implementation. By addressing the root cause of vulnerabilities found in previous encoding methods, we propose a balanced encoding technique that aims to minimize the problematic correlation with key-dependent intermediate values. We analyze the potential weaknesses associated with the balanced encoding and present a method that utilizes complementary sets of lookup tables. In this approach, the size of the lookup tables is approximately 512KB, and the number of table lookups is 1,024. This is comparable to the table size of non-protected white-box AES-128 implementations, while requiring only half the number of lookups. By adopting this method, our aim is to introduce a non-masking technique that mitigates the vulnerability to statistical analysis present in current internally-encoded AES implementations., Comment: 60 pages, 25 figures, submitted
- Published
- 2022
46. Interpretable Fusion Analytics Framework for fMRI Connectivity: Self-Attention Mechanism and Latent Space Item-Response Model
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Kim, Jeong-Jae, Jeon, Yeseul, Yu, SuMin, Choi, Junggu, and Han, Sanghoon
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Computer Science - Machine Learning ,Computer Science - Artificial Intelligence ,Electrical Engineering and Systems Science - Signal Processing ,Quantitative Biology - Neurons and Cognition - Abstract
There have been several attempts to use deep learning based on brain fMRI signals to classify cognitive impairment diseases. However, deep learning is a hidden black box model that makes it difficult to interpret the process of classification. To address this issue, we propose a novel analytical framework that interprets the classification result from deep learning processes. We first derive the region of interest (ROI) functional connectivity network (FCN) by embedding functions based on their similar signal patterns. Then, using the self-attention equipped deep learning model, we classify diseases based on their FCN. Finally, in order to interpret the classification results, we employ a latent space item-response interaction network model to identify the significant functions that exhibit distinct connectivity patterns when compared to other diseases. The application of this proposed framework to the four types of cognitive impairment shows that our approach is valid for determining the significant ROI functions., Comment: 38 pages,12 figures,3 tables
- Published
- 2022
47. Bigness of the tangent bundles of projective bundles over curves
- Author
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Kim, Jeong-Seop
- Subjects
Mathematics - Algebraic Geometry - Abstract
In this short article, we determine the bigness of the tangent bundle $T_X$ of the projective bundle $X=\mathbb{P}_C(E)$ associated to a vector bundle $E$ on a smooth projective curve $C$., Comment: 9 pages, error fixed
- Published
- 2022
48. Inflammation promotes synucleinopathy propagation.
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Kim, Tae-Kyung, Bae, Eun-Jin, Jung, Byung, Choi, Minsun, Shin, Soo, Park, Sung, Kim, Jeong, Jung, Min, Ulusoy, Ayse, Song, Mi-Young, Lee, Jun, Lee, He-Jin, Di Monte, Donato, and Lee, Seung-Jae
- Subjects
Mice ,Animals ,alpha-Synuclein ,Synucleinopathies ,Brain ,Neurodegenerative Diseases ,Inflammation ,Disease Models ,Animal - Abstract
The clinical progression of neurodegenerative diseases correlates with the spread of proteinopathy in the brain. The current understanding of the mechanism of proteinopathy spread is far from complete. Here, we propose that inflammation is fundamental to proteinopathy spread. A sequence variant of α-synuclein (V40G) was much less capable of fibril formation than wild-type α-synuclein (WT-syn) and, when mixed with WT-syn, interfered with its fibrillation. However, when V40G was injected intracerebrally into mice, it induced aggregate spreading even more effectively than WT-syn. Aggregate spreading was preceded by sustained microgliosis and inflammatory responses, which were more robust with V40G than with WT-syn. Oral administration of an anti-inflammatory agent suppressed aggregate spreading, inflammation, and behavioral deficits in mice. Furthermore, exposure of cells to inflammatory cytokines increased the cell-to-cell propagation of α-synuclein. These results suggest that the inflammatory microenvironment is the major driver of the spread of synucleinopathy in the brain.
- Published
- 2022
49. Correction: TNF-α promotes α-synuclein propagation through stimulation of senescence-associated lysosomal exocytosis
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Bae, Eun-Jin, Choi, Minsun, Kim, Jeong Tae, Kim, Dong-Kyu, Jung, Min Kyo, Kim, Changyoun, Kim, Tae-Kyung, Lee, Jun Sung, Jung, Byung Chul, Shin, Soo Jean, Rhee, Ka Hyun, and Lee, Seung-Jae
- Published
- 2024
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50. Correction: Inflammation promotes synucleinopathy propagation
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Kim, Tae-Kyung, Bae, Eun-Jin, Jung, Byung Chul, Choi, Minsun, Shin, Soo Jean, Park, Sung Jun, Kim, Jeong Tae, Jung, Min Kyo, Ulusoy, Ayse, Song, Mi-Young, Lee, Jun Sung, Lee, He-Jin, Di Monte, Donato A., and Lee, Seung-Jae
- Published
- 2024
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