28 results on '"Mark Um"'
Search Results
2. Phonon arithmetic in a trapped ion system
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Mark Um, Junhua Zhang, Dingshun Lv, Yao Lu, Shuoming An, Jing-Ning Zhang, Hyunchul Nha, M. S. Kim, and Kihwan Kim
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Science - Abstract
Single-quantum level operations are important tools for engineering desired quantum states, but they are inherently probabilistic operations with low experimental success rate. Here, the authors demonstrate near deterministic addition and subtraction of a single phonon of motion in a trapped Yb ion.
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- 2016
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3. Significant-loophole-free test of Kochen-Specker contextuality using two species of atomic-ions
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Pengfei Wang, Junhua Zhang, Chun-Yang Luan, Mark Um, Ye Wang, Mu Qiao, Tian Xie, Jing-Ning Zhang, Adán Cabello, and Kihwan Kim
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Quantum Physics ,81P13(Primary) 78A37(Secondary) ,Multidisciplinary ,FOS: Physical sciences ,Quantum Physics (quant-ph) - Abstract
Quantum measurements cannot be thought of as revealing preexisting results, even when they do not disturb any other measurement in the same trial. This feature is called contextuality and is crucial for the quantum advantage in computing. Here, we report the first observation of quantum contextuality simultaneously free of the detection, sharpness and compatibility loopholes. The detection and sharpness loopholes are closed by adopting a hybrid two-ion system and highly efficient fluorescence measurements offering a detection efficiency of $100\%$ and a measurement repeatability $>98\%$. The compatibility loophole is closed by targeting correlations between observables for two different ions in a Paul trap, a $^{171}\mathrm{Yb}^{+}$ ion and a $^{138}\mathrm{Ba}^{+}$ ion, chosen so measurements on each ion use different operation laser wavelengths, fluorescence wavelengths, and detectors. The experimental results show a violation of the bound for the most adversarial noncontextual models and open a new way to certify quantum systems., 8 pages, 6 figures, 1 table, 65 references
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- 2021
4. Single-qubit quantum memory exceeding ten-minute coherence time
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Luming Duan, Ming Lyu, Shuoming An, Jing Ning Zhang, Dahyun Yum, Kihwan Kim, Mark Um, Ye Wang, and Junhua Zhang
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Physics ,Quantum network ,Coherence time ,Dynamical decoupling ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,010305 fluids & plasmas ,Electronic, Optical and Magnetic Materials ,Qubit ,0103 physical sciences ,Quantum information ,Atomic physics ,010306 general physics ,Quantum ,Quantum money ,Quantum computer - Abstract
A long-time quantum memory capable of storing and measuring quantum information at the single-qubit level is an essential ingredient for practical quantum computation and com-munication. Recently, there have been remarkable progresses of increasing coherence time for ensemble-based quantum memories of trapped ions, nuclear spins of ionized donors or nuclear spins in a solid. Until now, however, the record of coherence time of a single qubit is on the order of a few tens of seconds demonstrated in trapped ion systems. The qubit coherence time in a trapped ion is mainly limited by the increasing magnetic field fluctuation and the decreasing state-detection efficiency associated with the motional heating of the ion without laser cooling. Here we report the coherence time of a single qubit over $10$ minutes in the hyperfine states of a \Yb ion sympathetically cooled by a \Ba ion in the same Paul trap, which eliminates the heating of the qubit ion even at room temperature. To reach such coherence time, we apply a few thousands of dynamical decoupling pulses to suppress the field fluctuation noise. A long-time quantum memory demonstrated in this experiment makes an important step for construction of the memory zone in scalable quantum computer architectures or for ion-trap-based quantum networks. With further improvement of the coherence time by techniques such as magnetic field shielding and increase of the number of qubits in the quantum memory, our demonstration also makes a basis for other applications including quantum money.
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- 2017
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5. Rapid transformation in aquatic food value chains in three Nigerian states
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Lenis Saweda O. Liverpool-Tasie, Ayala Wineman, Mark Umunna Amadi, Ayuba Gona, Chukwuemeka Chinonso Emenekwe, Ming Fang, Olawale Olunuga, Robert Ugochukwu Onyeneke, Sunday Norbert, Taiwo Mayomi Adenike, Thomas Reardon, and Ben Belton
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Nigeria ,value chain ,aquaculture ,capture fisheries ,micro ,small and medium enterprises (MSMEs) ,Aquaculture. Fisheries. Angling ,SH1-691 - Abstract
IntroductionNigeria is Africa’s most populous country, third largest fish producer, and second largest aquaculture producer. There have been numerous studies of aquaculture and fisheries in Nigeria, but no study to date has analyzed aquaculture and capture fisheries value chains together, while giving equal weight to all value chain segments and systematically capturing information on temporal trends in value chain structure, conduct, and performance. This paper does so.MethodsWe conducted a structured, qualitative, rapid reconnaissance survey of 180 actors from eight segments of the aquatic food value chain in three Nigerian states with contrasting geographies, Ebonyi, Kebbi, and Oyo.ResultsResults particularly important for future research and policy are as follows. (1) Partial vertical integration is a common feature of the organization of firms in all value chain segments, as a risk reduction strategy to overcome market imperfections and frictions. Scarcity and high cost of imported intermediate inputs is stimulating local innovation and import substitution manufacturing of feeds and fabricated items. (2) Inter-sectoral spillovers from the poultry industry have hastened the development of fish value chains, while improvements in power supply have enabled the expansion of cold storage capacity, facilitating the geographical lengthening of frozen fish value chains. (3) Rapid technological and/or institutional change is occurring in all value chain segments, including those usually viewed as traditional, such as processing and fishing. Logistics services are becoming more specialized and sophisticated, and digital communications technologies including social media play an increasingly important role in value chain coordination and marketing. (4) Increasing opportunity costs of time drive demand for convenience foods such as smoked and fried fish, which require little further preparation and can be stored at room temperature. Demand for farmed catfish is linked to growing consumption of food away from home at bars and restaurants. (5) Significant opportunities exist to improve the performance of value chains in terms of gender equity, environmental impacts, and food safety.
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- 2024
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6. Randomness expansion secured by quantum contextuality
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Hongyi Zhou, Xiongfeng Ma, Junhua Zhang, Qi Zhao, Mu Qiao, Kihwan Kim, Pengfei Wang, Mark Um, and Ye Wang
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Physics ,Discrete mathematics ,Quantum Physics ,Number generator ,Atomic Physics (physics.atom-ph) ,FOS: Physical sciences ,General Physics and Astronomy ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Kochen–Specker theorem ,Physics - Atomic Physics ,Quantum nonlocality ,Physics - Data Analysis, Statistics and Probability ,0103 physical sciences ,Quantum system ,Quantum Physics (quant-ph) ,010306 general physics ,0210 nano-technology ,Quantum ,Quantum contextuality ,Data Analysis, Statistics and Probability (physics.data-an) ,Randomness - Abstract
The output randomness from a random number generator can be certified by observing the violation of quantum contextuality inequalities based on the Kochen-Specker theorem. Contextuality can be tested in a single quantum system, which significantly simplifies the experimental requirements to observe the violation comparing to the ones based on nonlocality tests. However, it is not yet resolved how to ensure compatibilities for sequential measurements that is required in contextuality tests. Here, we employ a modified Klyachko-Can-Binicio\u{g}lu-Shumovsky contextuality inequality, which can ease the strict compatibility requirement on measurements. On a trapped single \Ba ion system, we experimentally demonstrate violation of the contextuality inequality and realize self-testing quantum random number expansion by closing detection loopholes. We perform $1.29 \times 10^8$ trials of experiments and extract the randomness of $8.06 \times 10^5$ bits with a speed of 270 bits s$^{-1}$. Our demonstration paves the way for the practical high-speed spot-checking quantum random number expansion and other secure information processing applications., Comment: Main text: 12 pages, 5 figures, Supplementary Materials: 5 pages
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- 2019
7. NOON States of Nine Quantized Vibrations in Two Radial Modes of a Trapped Ion
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Jing-Ning Zhang, Dingshun Lv, Luming Duan, Kihwan Kim, Junhua Zhang, and Mark Um
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Physics ,education.field_of_study ,Phonon ,Population ,Phase (waves) ,General Physics and Astronomy ,Coupling (probability) ,01 natural sciences ,010305 fluids & plasmas ,Quantum mechanics ,0103 physical sciences ,Quantum metrology ,Sensitivity (control systems) ,010306 general physics ,NOON state ,education ,Scaling - Abstract
We develop a deterministic method to generate and verify arbitrarily high NOON states of quantized vibrations (phonons), through the coupling to the internal state. We experimentally create the entangled states up to $N=9$ phonons in two vibrational modes of a single trapped ${^{171}\mathrm{Yb}}^{+}$ ion. We observe an increasing phase sensitivity of the generated NOON state as the number of phonons $N$ increases and obtain the fidelity from the contrast of the phase interference and the population of the phonon states through the two-mode projective measurement, which are significantly above the classical bound. We also measure the quantum Fisher information of the generated state and observe Heisenberg scaling in the lower bounds of phase sensitivity as $N$ increases. Our scheme is generic and applicable to other photonic or phononic systems such as circuit QED systems or nanomechanical oscillators, which have Jaynes-Cummings-type of interactions.
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- 2018
8. Correction: Corrigendum: Experimental Certification of Random Numbers via Quantum Contextuality
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Junhua Zhang, Yangchao Shen, Luming Duan, Mark Um, Dong-Ling Deng, Ye Wang, Kihwan Kim, and Xiang Zhang
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Multidisciplinary ,Computer science ,business.industry ,Certification ,Artificial intelligence ,computer.software_genre ,business ,computer ,Quantum contextuality ,Natural language processing - Abstract
Scientific Reports 3: Article number: 1627; published online: 09 April 2013; updated: 02 February 2018. The original version of this Article contained an error in the spelling of the author Yangchao Shen, which was incorrectly given as Shen Yangchao. This error has now been corrected in the PDF and HTML versions of the Article.
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- 2018
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9. Reconstruction of the Jaynes-Cummings field state of ionic motion in a harmonic trap
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Jing-Ning Zhang, Junhua Zhang, Mark Um, Kihwan Kim, Dingshun Lv, Myungshik Kim, Shuoming An, Engineering & Physical Science Research Council (E, and The Royal Society
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Density matrix ,DYNAMICS ,02 engineering and technology ,Physics, Atomic, Molecular & Chemical ,01 natural sciences ,WIGNER FUNCTION ,Superposition principle ,Quantum state ,Quantum mechanics ,TOMOGRAPHY ,0103 physical sciences ,Wigner distribution function ,010306 general physics ,COLLAPSE ,REVIVAL ,Quantum optics ,Physics ,Science & Technology ,Optics ,QUANTUM-STATE ,ATOM ,021001 nanoscience & nanotechnology ,Quantum technology ,MODEL ,QUASI-PROBABILITY DISTRIBUTIONS ,Phase space ,Physical Sciences ,Coherent states ,SCHRODINGER-CAT STATES ,0210 nano-technology - Abstract
A quantum state is fully characterized by its density matrix or equivalently by its quasiprobabilities in phase space. A scheme to identify the quasiprobabilities of a quantum state is an important tool in the recent development of quantum technologies. One of the most fundamental interaction models in quantum optics is the so-called Jaynes-Cummings model (JCM), which has been massively studied theoretically and experimentally. However, the expected essential dynamics of the field states under the resonant JCM has not been observed experimentally due to the lack of a proper reconstruction scheme. In this paper, we further develop a highly efficient vacuum measurement scheme and study the JCM dynamics in a trapped ion system with the capability of the vacuum measurement to reconstruct its quasiprobability $Q$ function, which is a preferred choice to study the core of the dynamics of a quantum state in phase space. During the JCM dynamics, the Gaussian peak of the initial coherent state bifurcates and rotates around the origin of phase space. They merge at the so-called revival time at the other side of phase space. The measured $Q$ function agrees with the theoretical prediction. Moreover, we reconstruct the Wigner function by deconvoluting the $Q$ function and observe the quantum interference in the Wigner function at half of the revival time, where the vibrational state becomes nearly disentangled from the internal energy states and forms a superposition of two composite states. The scheme can be applied to other physical setups including cavity or circuit-QED and optomechanical systems.
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- 2017
10. Experimental test of the quantum Jarzynski equality with a trapped-ion system
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Junhua Zhang, Shuoming An, Dingshun Lv, Kihwan Kim, Yao Lu, Haitao Quan, Zhang-qi Yin, Mark Um, and Jing-Ning Zhang
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Physics ,Quantum Physics ,Jarzynski equality ,Statistical Mechanics (cond-mat.stat-mech) ,Quantum mechanics ,FOS: Physical sciences ,General Physics and Astronomy ,Quantum Physics (quant-ph) ,Quantum ,Condensed Matter - Statistical Mechanics ,Ion - Abstract
The past two decades witnessed important developments in the field of non-equilibrium statistical mechanics. Among these developments, the Jarzynski equality, being a milestone following the landmark work of Clausius and Kelvin, stands out. The Jarzynski equality relates the free energy difference between two equilibrium states and the work done on the system through far from equilibrium processes. While experimental tests of the equality have been performed in classical regime, the verification of the quantum Jarzynski equality has not yet been fully demonstrated due to experimental challenges. Here, we report an experimental test of the quantum Jarzynski equality with a single \Yb ion trapped in a harmonic potential. We perform projective measurements to obtain phonon distributions of the initial thermal state. Following that we apply the laser induced force on the projected energy eigenstate, and find transition probabilities to final energy eigenstates after the work is done. By varying the speed of applying the force from equilibrium to far-from equilibrium regime, we verified the quantum Jarzynski equality in an isolated system., 18 pages, 4 figures, 1 table
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- 2014
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11. Frequency stabilization of a 650 nm laser to an I2 spectrum for trapped Ba138+ ions
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Junhua Zhang, Naijun Jin, Pengfei Wang, Ye Wang, Mark Um, Kihwan Kim, and Tian Xie
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Materials science ,Resonance ,Statistical and Nonlinear Physics ,Laser ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Spectral line ,law.invention ,010309 optics ,Optical pumping ,law ,Optical cavity ,Fiber laser ,Laser cooling ,0103 physical sciences ,Atomic physics ,Doppler cooling - Abstract
Optical manipulation of Ba+ ions is performed mainly by a 493 nm laser for the S1/2−P1/2 transition and a 650 nm laser for the P1/2−D3/2 transition. Because the branching ratio between the 493 and 650 nm transitions of a single Ba+ ion is comparable, stabilization systems of both lasers are equally important for Doppler cooling, sub-Doppler cooling, optical pumping, and state detection. The stabilization system of a 493 nm laser to an absolute Te2 reference has been well established. However, the stabilization of a 650 nm laser to the absolute reference of an atomic or molecular spectrum has not been presented before, to our knowledge. Here, we experimentally obtain the I2 spectrum near 650 nm and provide the experimental connection to the spectrum of Ba+. We present the 20 spectral lines of I2 in the range of 0.9 GHz above the resonance of the P1/2−D3/2 transition. We stabilize the 650 nm laser through the optical cavity to the lowest one among these lines, which is about 350 MHz apart, as the absolute frequency reference. Finally, we measure the frequency differences between these iodine lines and the Ba+ resonance through the fluorescence excitation spectrum with well-resolved dark states, which is in agreement with the theoretical expectation. The presented stabilization scheme enables us to perform precise experiments with Ba+ ions.
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- 2019
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12. Contextualized High School Performance: Evidence to Inform Equitable Holistic, Test-Optional, and Test-Free Admissions Policies
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Michael N. Bastedo, Mark Umbricht, Emma Bausch, Bo-Kyung Byun, and Yiping Bai
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Education - Abstract
Holistic admissions practices require evaluating an applicant’s credentials in light of the opportunities available in their high school context. High school grades, test scores, and course taking are clearly related to college grades, retention, and graduation. But does performance in high school context also relate to college success? Building a unique dataset of 2.3 million students in a Midwestern state, we find that contextualized indicators of high school grades and standardized tests are strongly associated with student success in college, validating their use in holistic admissions. Contextualized grades have a stronger and more consistent association with college success than contextualized test scores, and may be most helpful at test-optional, test-free, and broader-access colleges that have yet to adopt holistic admissions practices.
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- 2023
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13. Author Correction: Single-qubit quantum memory exceeding ten-minute coherence time
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Shuoming An, Ming Lyu, Luming Duan, Dahyun Yum, Kihwan Kim, Junhua Zhang, Jing Ning Zhang, Mark Um, and Ye Wang
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Physics ,Coherence time ,Qubit ,Quantum mechanics ,0103 physical sciences ,Phase noise ,010306 general physics ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Quantum memory ,010305 fluids & plasmas ,Electronic, Optical and Magnetic Materials - Abstract
In the version of this Letter originally published, in Fig. 2c legend, the entry ‘LO phase noise’ should not have been included. This has now been corrected in the online versions.
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- 2018
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14. Testing nonclassicality and non-Gaussianity in phase space
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Junhua Zhang, Jiyong Park, Jaehak Lee, Se Wan Ji, Dingshun Lv, Hyunchul Nha, Mark Um, and Kihwan Kim
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Physics ,Quantum Physics ,Gaussian ,General Physics and Astronomy ,FOS: Physical sciences ,Gaussian random field ,symbols.namesake ,Optical phase space ,Quantum nonlocality ,Quantum mechanics ,Phase space ,Non-Gaussianity ,symbols ,Gaussian function ,Coherent states ,Quantum Physics (quant-ph) - Abstract
We theoretically propose and experimentally demonstrate a nonclassicality test of single-mode field in phase space, which has an analogy with the nonlocality test proposed by Banaszek and Wodkiewicz [Phys. Rev. Lett. 82, 2009 (1999)]. Our approach to deriving the classical bound draws on the fact that the Wigner function of a coherent state is a product of two independent distributions as if the orthogonal quadratures (position and momentum) in phase space behave as local realistic variables. Our method detects every pure nonclassical Gaussian state, which can also be extended to mixed states. Furthermore, it sets a bound for all Gaussian states and their mixtures, thereby providing a criterion to detect a genuine quantum non-Gaussian state. Remarkably, our phase-space approach with invariance under Gaussian unitary operations leads to an optimized test for a given non-Gaussian state. We experimentally show how this enhanced method can manifest quantum non-Gaussianity of a state by simply choosing phase-space points appropriately, which is essentially equivalent to implementing a squeezing operation on a given state., Comment: 5 pages and 3 figures with Supplemental Material, published version
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- 2015
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15. Urological Involvement in the Multidisciplinary Management of Placenta Accreta Spectrum in a Centralised, High-Volume Centre: A Retrospective Analysis
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Brian D. Kelly, Rebecca Moorhead, David Wetherell, Tracey Gilchrist, Marcalain Furrer, Marlon Perera, Briony Norris, David Wrede, Mark Umstad, Jamie Kearsley, and Faris Al-Shammaa
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placenta accreta spectrum ,placenta percreta ,placenta accreta ,placenta increta ,multidisciplinary managemen ,Diseases of the genitourinary system. Urology ,RC870-923 - Abstract
Objectives: Placenta accreta spectrum (PAS) significantly increases the complexity of childbirth and frequently involves urologic organs. Multidisciplinary team (MDT) care is paramount to ensure optimal outcomes. We aimed to evaluate urologic interventions in patients with PAS at a centralised, tertiary referral centre. Methods: An analysis of a prospectively collected data set, consisting of all women presenting with PAS at our institution between November 2013 and June 2019. Patients who required urological intervention were identified, and perioperative details were retrieved. Results: Forty-two cases of PAS were identified. The mean maternal age was 35 years, and mean gestational age at delivery was 34 weeks. Thirty-seven cases were managed electively, with 5 cases managed conservatively (no hysterectomy) and 5 requiring emergency management. Fifteen patients (36%) had suspected bladder invasion on MRI. A total of 36 patients (86%) had ureteric catheters inserted, 14 (33%) required bladder repair, and 2 had ureteric injurie s (5%). Conclusions: PAS frequently requires urological intervention to prevent and repair injury to the urinary bladder and ureter. PAS is a rare condition that is best managed in an MDT setting in a centralised, tertiary, high-volume centre with access to a variety of medical and surgical sub-specialities
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- 2022
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16. Experimental Certification of Random Numbers via Quantum Contextuality
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Luming Duan, Kihwan Kim, Xiang Zhang, Mark Um, Ye Wang, Dong-Ling Deng, Junhua Zhang, and Shen Yangchao
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Multidisciplinary ,Inequality ,Computer science ,media_common.quotation_subject ,Statistical physics ,Corrigenda ,Quantum contextuality ,Confidence interval ,Randomness ,Article ,Minimum entropy ,media_common - Abstract
The intrinsic unpredictability of measurements in quantum mechanics can be used to produce genuine randomness. Here, we demonstrate a random number generator where the randomness is certified by quantum contextuality in connection with the Kochen-Specker theorem. In particular, we generate random numbers from measurements on a single trapped ion with three internal levels, and certify the generated randomness by showing a bound on the minimum entropy through observation of violation of the Klyachko-Can-Binicioglu-Shumovsky (KCBS) inequality. Concerning the test of the KCBS inequality, we close the detection efficiency loophole for the first time and make it relatively immune to the compatibility loophole. In our experiment, we generate 1 × 10(5) random numbers that are guaranteed to have 5.2 × 10(4) bits of minimum entropy with a 99% confidence level.
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- 2013
17. State-independent experimental test of quantum contextuality with a single trapped ion
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Mark Um, Xiang Zhang, Luming Duan, Ye Wang, Chao Shen, Kihwan Kim, Shuoming An, Dong-Ling Deng, and Junhua Zhang
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Physics ,Measurement theory ,Quantum mechanics ,General Physics and Astronomy ,Quantum Physics ,State (functional analysis) ,Qutrit ,Atomic physics ,Quantum contextuality ,Quantum ,Ion trapping ,Microwave ,Ion - Abstract
Using a single trapped ion, we have experimentally demonstrated state-independent violation of a recent version of the Kochen-Specker inequality in a three-level system (qutrit) that is intrinsically indivisible. Three ground states of the $^{171}\mathrm{Yb}^{+}$ ion representing a qutrit are manipulated with high fidelity through microwaves and detected with high efficiency through a two-step quantum jump technique. Qutrits constitute the most fundamental system to show quantum contextuality and our experiment represents the first one that closes the detection efficiency loophole for experimental tests of quantum contextuality in such a system.
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- 2012
18. Biofortification in Nigeria: A systematic review
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Robert Ugochukwu Onyeneke, Mark Umunna Amadi, and Francis Chidi Anosike
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adoption ,biofortification ,constraints ,delivery strategies ,determinants ,Agriculture (General) ,S1-972 ,Food processing and manufacture ,TP368-456 - Abstract
This paper classified the delivery strategy of pro-vitamin A biofortified crops in Nigeria and characterized the adoption pattern, determinants, and constraints to adoption. Forty papers were reviewed based on delivery strategies and organized into nine categories with cost effectiveness having the highest number of papers mentioned while sustainable approach has the least. Delivery authority, type of breeding technology, location-specific variable, farmland ownership and yield of improved varieties were determinants of adoption of biofortified cassava varieties stated in the papers. Major constraints to adoption included availability of resources, enabling environment for biofortification and undesirable traits due to instability of vitamin A during processing. The study concluded that the delivery strategies are similar to Harvestplus approach. Collaboration between Harvestplus and other agricultural research institutes in Nigeria was recommended.
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- 2019
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19. Adoption of Bio-fortified Pro-Vitamin-A Cassava and Health Outcome of Farming Households in Abia and Anambra States Nigeria
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Robert Ugochukwu Onyeneke, Chukwuemeka Chinonso Emenekwe, Jane Onuabuchi Munonye, Michael Olatunji Olaolu, Chibuzo Uzoma Izuogu, Sikiru Ibrahim-Olesin, Mark Umunna Amadi, Chukwudi Loveday Njoku, and Joy Nneamaka Obi
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Agriculture (General) ,S1-972 - Abstract
This study examined the relationship between the adoption of bio-fortified pro-vitamin-A cassava varieties and farming households’ health outcomes using cross sectional data obtained from 318 cassava farmers in southeast Nigeria. The data was analysed using binary logistic regression, propensity score matching of treatment effects and percentages. The study found that number of children under five, household size, education of head of household, extension service, ownership of television, radio, mobile phone and tricycle, membership of cooperative societies, and access to credit were the significant predictors of adoption of pro-vitamin-A bio-fortified cassava varieties in the States. The study also found that the main constraints militating against adoption of pro-vitamin-A bio-fortified cassava include decaying of roots immediately after maturation, high cost of cassava stem, and high moisture content. The estimate of the effect of the adoption of bio-fortified pro-vitamin-A cassava varieties on incidence of vitamin-A deficiency related diseases was significant with an average treatment effect on the adopters of -0.463. The adoption of bio-fortified pro-vitamin-A cassava varieties has substantial effect on the reduction of vitamin-A deficiency related health outcomes. There is need for wider awareness and dissemination of the varieties among cassava farmers, while interventions should target the promotion of both production and consumption of such cassava varieties.
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- 2020
20. Optimizing the Power Usage of Anti-Sweat Heaters in Glass-Door Refrigerators According to the Dew Point
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Iztok Humar, Uroš Hudomalj, Alexander Marinšek, and Mark Umberger
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anti-sweat heaters ,condensation ,glass-door refrigerators ,dew point ,energy savings ,Technology - Abstract
Putting glass doors on the display cases of refrigerators is one of the most efficient ways to reduce the energy consumption of supermarkets. However, the glass fogs up when opening the door because of the difference in air temperature inside and outside of the refrigerator, thereby obscuring the view. To defog the glass, anti-sweat heaters (ASHs) are used. In this paper, the power usage of ASHs according to changes in the dew point (DP) inside a supermarket were evaluated for two types of ASH, i.e., the door-frame ASH and the glass ASH. The evaluation was based on measurements of the condensation on the glass doors of vertical display cases, used for the preservation of frozen foodstuffs. A mathematical model of the correlation between the ASH’s power usage and the DP was developed and used for predicting the long-term energy savings. The savings were calculated based on the measured DPs inside the supermarket, which were extrapolated over a longer time period based on their correlation with the outside DPs. Regulating the door-frame ASH according to the DP resulted in an 84.6% reduction in energy consumption and a 90.1% reduction in the case of the glass ASH, compared to the current state. The correlation between the DPs inside and outside the supermarket served as a basis for the proposed implementation of the power usage regulation of the ASH according to the DP.
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- 2022
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21. State-Independent Experimental Test of Quantum Contextuality with a Single Trapped Ion.
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Xiang Zhang, Mark Um, Junhua Zhang, Shuoming An, Ye Wang, Dong-ling Deng, Chao Shen, Lu-Ming Duan, and Kihwan Kim
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- *
QUANTUM theory , *ION traps , *MICROWAVES , *CONTEXTUAL analysis , *BELL'S theorem - Abstract
Using a single trapped ion, we have experimentally demonstrated state-independent violation of a recent version of the Kochen-Specker inequality in a three-level system (qutrit) that is intrinsically indivisible. Three ground states of the 171Yb+ ion representing a qutrit are manipulated with high fidelity through microwaves and detected with high efficiency through a two-step quantum jump technique. Qutrits constitute the most fundamental system to show quantum contextuality and our experiment represents the first one that closes the detection efficiency loophole for experimental tests of quantum contextuality in such a system. [ABSTRACT FROM AUTHOR]
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- 2013
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22. Climate Change Perception and Uptake of Climate-Smart Agriculture in Rice Production in Ebonyi State, Nigeria
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Robert Ugochukwu Onyeneke, Mark Umunna Amadi, Chukwudi Loveday Njoku, and Emeka Emmanuel Osuji
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climate change ,perception ,rice farming ,climate-smart agriculture ,principal component analysis ,multivariate probit regression ,Meteorology. Climatology ,QC851-999 - Abstract
Rice production in Nigeria is vulnerable to climate risks and rice farmers over time have experienced the risks and their respective impacts on rice farming. Rice farmers have also responded to perceived climate risks with strategies believed to be climate-smart. Farmers’ perception of climate risks is an important first step of determining any action to be taken to counteract the negative effects of climate change on agriculture. Studies on the link between perceived climate risks and farmers’ response strategies are increasing. However, there are limited studies on the determinants of rice farmers’ perception of climate events. The paper therefore examined climate change perception and uptake of climate-smart agriculture in rice production in Ebonyi State, Nigeria using cross-sectional data from 347 rice farmers in an important rice-producing area in Nigeria. Principal component analysis, multivariate probit regression model and descriptive statistics were adopted for data analysis. Perceived climate events include increased rainfall intensity, prolonged dry seasons, frequent floods, rising temperature, severe windstorms, unpredictable rainfall pattern and distribution, late onset rain, and early cessation of rain. Farmers’ socioeconomic, farm and institutional characteristics influenced their perception of climate change. Additionally, rice farmers used a variety of climate-smart practices and technologies to respond to the perceived climate events. Such climate-smart practices include planting improved rice varieties, insurance, planting different crops, livelihood diversification, soil and water conservation techniques, adjusting planting and harvesting dates, irrigation, reliance on climate information and forecasts, planting on the nursery, appropriate application of fertilizer and efficient and effective use of pesticides. These climate-smart agricultural measures were further delineated into five broad packages using principal component analysis. These packages include crop and land management practices, climate-based services and irrigation, livelihood diversification and soil fertility management, efficient and effective use of pesticide and planting on the nursery. High fertilizer costs, lack of access to inputs, insufficient land, insufficient capital, pests and diseases, floods, scorching sun, high labour cost, insufficient climate information, and poor extension services were the barriers to uptake of climate-smart agriculture in rice production. Rice farmers should be supported to implement climate-smart agriculture in rice production in order to achieve the objectives of increased rice productivity and income, food security, climate resilience and mitigation.
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- 2021
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23. Migration and Agricultural Investment in Southeast, Nigeria
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Robert Ugochukwu Onyeneke, Chinyere Augusta Nwajiuba, Jane Munonye, Christiana Ogonna Igberi, Jonathan Ogbeni Aligbe, and Mark Umunna Amadi
- Subjects
Agriculture (General) ,S1-972 - Abstract
Gender shapes migration and agricultural investments in farming households. Despite indications that gender plays an important role in driving migration and remittance, research in this context is limited. This study therefore, explored rural-urban migration and agricultural investment in Southeast Nigeria. The study adopted a multi-stage sampling technique in the selection of respondents. Cross-sectional data gathered from 200 household heads (100 male-headed households and 100 female-headed households) was used. Using descriptive statistics and ordinary least square regression the findings reveal that majority of male and female migrants (60% and 55% respectively) in male-headed households migrated in search of jobs. Majority of male and female migrants in female-headed households (50% and 55% respectively) migrated in search of jobs. The major determinants of migration were gender of the migrant, gender of the household head, age, income, access to credit, number of migrants in the working age, occupation and number of livelihood activities pursued by the household. The average annual remittance from male migrants in male-headed households was N204,269.3 while that of their female counterparts was N161,297.76. The average annual remittance from male migrants in female-headed households was N189,282.9 while that of their female counterparts was N170,297.8. The average amount of remittance invested in agriculture in male-headed households was N131,334.8 while that of their female counterparts was N151,676.5. The study concludes that gender drives migration, remittances from both the sender and receiver perspectives and household investment decisions. It is however recommended that gender should be mainstreamed in migration policies to consider the peculiarities of both men and women in migration and remittances.
- Published
- 2019
24. Of mice and men: a novel dietary supplement for the treatment of ulcerative colitis
- Author
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Shiran Shapira, Ari Leshno, Daniel Katz, Nitsan Maharshak, Gil Hevroni, Maayan Jean-David, Sarah Kraus, Lior Galazan, Ilan Aroch, Dina Kazanov, Aharon Hallack, Stewart Becker, Mark Umanski, Menachem Moshkowitz, Iris Dotan, and Nadir Arber
- Subjects
Diseases of the digestive system. Gastroenterology ,RC799-869 - Abstract
Background: Curcumin, green tea polyphenols and selenium possess anti-inflammatory and anti-oxidant properties. Individually they have demonstrated some efficacy in animal models and human subjects with inflammatory bowel disease (IBD). To evaluate the efficacy and safety of Coltect [Curcumin (500 mg), green tea (250 mg) and selenium (100 µg)] in vivo and in patients with ulcerative colitis (UC). Methods: Each component was compared to placebo in a DSS mice colitis model. The efficacy was validated in a 2,4,6-trinitrobenzenesulfonic acid (TNBS) rat colitis model. Twenty patients with mild-to-moderate UC received two Coltect tablets twice daily for 8 weeks. Enrollees underwent sigmoidoscopy at study entrance and closure, and physical and laboratory evaluation at baseline, 4 and 8 weeks. Results: Coltect showed a synergistic therapeutic effect in the DSS and TNBS models. Disease activity was significantly higher in the placebo versus the treated group ( p < 0.05). Selenium was the more active component. The contribution of green tea was minor. In the TNBS model, the Wallace scores for macroscopic lesions were 4.8 ± 1.5 (treatment) and 8.2 ± 0.5 (placebo) ( p = 0.01). In humans, Coltect was well tolerated and effective. Fourteen subjects (70%) improved: nine (45%) went into complete remission, four (20%) experienced marked improvement and one (5%) experienced moderate improvement at the end of the trial. Clinical activity index decreased significantly at 4 and 8 weeks ( p < 0.001). Two patients had no change in their symptoms, and one withdrew after 4 weeks. Flare-up in four subjects caused three to withdraw from the study after less than 4 weeks. Endoscopic improvement was observed in 11 (69%) patients, and four patients (25%) achieved complete remission. Conclusions: Coltect may serve as a first-line or add-on therapy in patients with mild-to-moderate UC.
- Published
- 2018
- Full Text
- View/download PDF
25. Progress in Climate–Agricultural Vulnerability Assessment in Nigeria
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Robert Ugochukwu Onyeneke, Chukwuemeka Chinonso Emenekwe, Jane Onuabuchi Munonye, Chinyere Augusta Nwajiuba, Uwazie Iyke Uwazie, Mark Umunna Amadi, Chibuzo Uzoma Izuogu, Chukwudi Loveday Njoku, and Louis Uchenna Onyeneke
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temperature ,precipitation ,trend analysis ,vulnerability assessment ,climate change ,agriculture ,nigeria ,Meteorology. Climatology ,QC851-999 - Abstract
An in-depth understanding of the impact of vulnerability on livelihoods and food security is important in deploying effective adaptation actions. The Nigerian agricultural sector is dominated by rainfed and non-homogenous smallholder farming systems. A number of climate change risk studies have emerged in the last decade. However, little attention has been given to vulnerability assessments and the operationalization of vulnerability. To highlight this shortcoming, this study systematically reviewed climate-change-focused vulnerability assessments in the agricultural sector by evaluating (1) variation in climate variables in Nigeria over time; (2) the state of climate change vulnerability assessment in Nigerian agriculture; (3) the theoretical foundations, operationalization approaches, and frameworks of vulnerability assessments in Nigeria; (4) the methods currently used in vulnerability assessments; and (5) lessons learned from the vulnerability studies. We used a linear trend of climatic data spanning over a period of 56 years (1961−2016) obtained from the Nigerian Meteorological Agency and the Climate Research Unit of the University of East Anglia, United Kingdom, along with a systematic review of literature to achieve the objectives. The analysis indicates a significant and positive correlation between temperature and time in all major agro-ecological zones. For precipitation, we found a non-significant correlation between precipitation in the Sahel, Sudan, and Guinea Savanna zones with time, while the other zones recorded positive but significant associations between precipitation and time. The systematic review findings indicate no clear progress in publications focused specifically on vulnerability assessments in the Nigerian agricultural sector. There has been progress recently in applying frameworks and methods. However, there are important issues that require addressing in vulnerability assessments, including low consideration for indigenous knowledge and experience, unclear operationalization of vulnerability, non-standardization of vulnerability measures, and inadequacy of current assessments supporting decision making.
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- 2020
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26. Testing Nonclassicality and Non-Gaussianity in Phase Space.
- Author
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Jiyong Park, Junhua Zhang, Jaehak Lee, Se-Wan Ji, Mark Um, Dingshun Lv, Kihwan Kim, and Hyunchul Nha
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- *
GAUSSIAN processes , *PHASE space , *ANALOGY , *SQUEEZED light - Abstract
We theoretically propose and experimentally demonstrate a nonclassicality test of a single-mode field in phase space which has an analogy with the nonlocality test proposed by Banaszek and Wódkiewicz [Phys. Rev. Lett. 82 2009 (1999)]. Our approach to deriving the classical bound draws on the fact that the Wigner function of a coherent state is a product of two independent distributions as if the orthogonal quadratures (position and momentum) in phase space behave as local realistic variables. Our method detects every pure nonclassical Gaussian state which can also be extended to mixed states. Furthermore it sets a bound for all Gaussian states and their mixtures thereby providing a criterion to detect a genuine quantum non-Gaussian state. Remarkably our phase-space approach with invariance under Gaussian unitary operations leads to an optimized test for a given non-Gaussian state. We experimentally show how this enhanced method can manifest quantum non-Gaussianity of a state by simply choosing phase-space points appropriately which is essentially equivalent to implementing a squeezing operation on a given state. [ABSTRACT FROM AUTHOR]
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- 2015
- Full Text
- View/download PDF
27. Haematoma in the airways as the first symptom of acquired haemophilia A.
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Bick L, Lauritzen UM, Andersen S, Galili J, and Blichfeldt-Eckhardt L
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- Male, Humans, Aged, Hematoma diagnosis, Hemophilia A complications, Hemophilia A diagnosis, Autoimmune Diseases
- Abstract
Acquired haemophilia A (AHA) is a rare autoimmune disorder resulting from antibodies against coagulation factor VIII. AHA causes severe, unexpected bleeding which may be life-threatening and should be considered when a patient with no previous history of bleeding presents with spontaneous bleeding and a prolonged APTT. This case report describes onset of AHA of a 75-year-old male who was admitted to Vejle Hospital with acute need for intubation due to breathing and swallowing problems caused by supraglottic haematoma. The case was complicated by anticoagulant treatment with rivaroxaban.
- Published
- 2022
28. Vocal cord augmentation in a palliative setting for patients with lung cancer and mediastinal involvement.
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Lauridsen UM, Schultz JDJH, Nyhus CH, and Sørensen JR
- Subjects
- Humans, Quality of Life, Mediastinum, Palliative Care, Vocal Cords, Lung Neoplasms
- Abstract
Injection augmentation of the vocal cords is a recognized treatment modality in patients with glottal closure deficiency caused by paresis or paralysis of the vocal cord. The treatment can improve voice quality and also quality of life. It is preferable to minimize waiting time for the procedure for patients with lung cancer and mediastinal involvement, because the one-year mortality is above 40%, as argued in this review.
- Published
- 2022
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