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794 results on '"Bart, H."'

1. Hunting for Polluted White Dwarfs and Other Treasures with Gaia XP Spectra and Unsupervised Machine Learning

Author

Kao, Malia L., Hawkins, Keith, Rogers, Laura K., Bonsor, Amy, Dunlap, Bart H., Sanders, Jason L., Montgomery, M. H., and Winget, D. E.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Earth and Planetary Astrophysics, Computer Science - Machine Learning
Abstract

White dwarfs (WDs) polluted by exoplanetary material provide the unprecedented opportunity to directly observe the interiors of exoplanets. However, spectroscopic surveys are often limited by brightness constraints, and WDs tend to be very faint, making detections of large populations of polluted WDs difficult. In this paper, we aim to increase considerably the number of WDs with multiple metals in their atmospheres. Using 96,134 WDs with Gaia DR3 BP/RP (XP) spectra, we constructed a 2D map using an unsupervised machine learning technique called Uniform Manifold Approximation and Projection (UMAP) to organize the WDs into identifiable spectral regions. The polluted WDs are among the distinct spectral groups identified in our map. We have shown that this selection method could potentially increase the number of known WDs with 5 or more metal species in their atmospheres by an order of magnitude. Such systems are essential for characterizing exoplanet diversity and geology., Comment: 16 pages, 10 figures, accepted to ApJ on June 13, 2024

Published
2024

2. Fluid Mixing during Phase Separation in Crystallizing White Dwarfs

Author

Montgomery, M. H. and Dunlap, Bart H.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Physics - Geophysics
Abstract

Accurate models of cooling white dwarfs must treat the energy released as their cores crystallize. This phase transition slows the cooling by releasing latent heat and also gravitational energy, which results from phase separation: liquid C is released from the solid C/O core, driving an outward carbon flux. The Gaia color-magnitude diagram provides striking confirmation of this theory by revealing a mass-dependent overdensity of white dwarfs, indicating slowed cooling at the expected location. However, the observed overdensity is enhanced relative to the models. Additionally, it is associated with increased magnetism, suggesting a link between crystallization and magnetic field generation. Recent works aimed at explaining an enhanced cooling delay and magnetic field generation employ a uniform mixing prescription that assumes large-scale turbulent motions; we show here that these calculations are not self-consistent. We also show that thermohaline mixing is most likely efficient enough to provide the required chemical redistribution during C/O phase separation, and that the resulting velocities and mixing lengths are much smaller than previous estimates. These reduced fluid motions cannot generate measurable magnetic fields, suggesting any link with crystallization needs to invoke a separate mechanism. Finally, this mixing alters the chemical profiles which in turn affects the frequencies of the pulsation modes., Comment: 13 pages, 7 figures, accepted for publication in the ApJ

Published
2023

6. Symmetry and Voltmeters

Author

McGuyer, Bart H.

Subjects
Physics - Physics Education
Abstract

Letter to the Editor that explains a popular demonstration with voltmeters and electromotive force using symmetry., Comment: 1 page

Published
2021
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7. Diet Soda and Liquid Nitrogen

Author

McGuyer, Bart H., Brown, Justin M., and Dang, Hoan B.

Subjects
Physics - Physics Education
Abstract

Letter to the Editor about how the diet soda and Mentos reaction can be produced by the direct immersion of a plastic soda bottle in liquid nitrogen., Comment: 1 page

Published
2021
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8. Frequency-dependent capacitors using paper

Author

McGuyer, Bart H.

Subjects
Physics - Physics Education
Abstract

Measurements of capacitors made with paper sheets reveal a significant decrease in capacitance with increasing frequency from 10 to 100,000 Hz, offering a simple demonstration of complex dielectric phenomena using common equipment., Comment: 3 pages, 2 figures

Published
2021
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11. Modelling Sovereign Credit Ratings: Evaluating the Accuracy and Driving Factors using Machine Learning Techniques

Author

Overes, Bart H. L. and van der Wel, Michel

Subjects
Quantitative Finance - Statistical Finance, Computer Science - Machine Learning
Abstract

Sovereign credit ratings summarize the creditworthiness of countries. These ratings have a large influence on the economy and the yields at which governments can issue new debt. This paper investigates the use of a Multilayer Perceptron (MLP), Classification and Regression Trees (CART), Support Vector Machines (SVM), Na\"ive Bayes (NB), and an Ordered Logit (OL) model for the prediction of sovereign credit ratings. We show that MLP is best suited for predicting sovereign credit ratings, with a random cross-validated accuracy of 68%, followed by CART (59%), SVM (41%), NB (38%), and OL (33%). Investigation of the determining factors shows that there is some heterogeneity in the important variables across the models. However, the two models with the highest out-of-sample predictive accuracy, MLP and CART, show a lot of similarities in the influential variables, with regulatory quality, and GDP per capita as common important variables. Consistent with economic theory, a higher regulatory quality and/or GDP per capita are associated with a higher credit rating.

Published
2021

12. I Spy Transits and Pulsations: Empirical Variability in White Dwarfs Using Gaia and the Zwicky Transient Facility

Author

Guidry, Joseph A., Vanderbosch, Zachary P., Hermes, J. J., Barlow, Brad N., Lopez, Isaac D., Boudreaux, Emily M., Corcoran, Kyle A., Bell, Keaton J., Montgomery, M. H., Heintz, Tyler M., Castanheira, Barbara G., Reding, Joshua S., Dunlap, Bart H., Winget, D. E., Winget, Karen I., and Kuehne, J. W.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

We present a novel method to detect variable astrophysical objects and transient phenomena using anomalous excess scatter in repeated measurements from public catalogs of Gaia DR2 and Zwicky Transient Facility (ZTF) DR3 photometry. We first provide a generalized, all-sky proxy for variability using only Gaia DR2 photometry, calibrated to white dwarf stars. To ensure more robust candidate detection, we further employ a method combining Gaia with ZTF photometry and alerts. To demonstrate the efficacy, we apply this latter technique to a sample of roughly $12,100$ white dwarfs within 200 pc centered on the ZZ Ceti instability strip, where hydrogen-atmosphere white dwarfs are known to pulsate. Through inspecting the top $1\%$ samples ranked by these methods, we demonstrate that both the Gaia-only and ZTF-informed techniques are highly effective at identifying known and new variable white dwarfs, which we verify using follow-up, high-speed photometry. We confirm variability in all 33 out of 33 ($100\%$) observed white dwarfs within our top $1\%$ highest-ranked candidates, both inside and outside the ZZ Ceti instability strip. In addition to dozens of new pulsating white dwarfs, we also identify five white dwarfs highly likely to show transiting planetary debris; if confirmed, these systems would more than triple the number of white dwarfs known to host transiting debris., Comment: 30 pages, 14 figures, revised and accepted to ApJ on March 11, 2021

Published
2020
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13. Evaluation of factors associated with bulk milk somatic cell count and total plate count in Indonesian smallholder dairy farms

Author

Achmad Fadillah, Bart H. P. van den Borne, Okti Nadia Poetri, Henk Hogeveen, Thomas Slijper, Herwin Pisestyani, and Ynte H. Schukken

Subjects
dairy cattle, udder health, milk quality, total plate count, somatic cell count, generalized estimating equations, Veterinary medicine, SF600-1100
Abstract

Increasing milk quality in smallholder dairy farms will result in a greater quantity of milk being delivered to milk collection centers, an increased milk price for farmers and consequently an improved farmers’ livelihood. However, little research on milk quality has been performed on smallholder farms in Southeast Asia. The objective of this study was to identify risk factors associated with somatic cell count (SCC) and total plate count (TPC) in Indonesian smallholder dairy farms. One dairy cooperative in West Java, Indonesia was selected based on its willingness to participate. All 119 member farmers in the cooperative, clustered in six groups, were interviewed and a bulk milk sample from all farms was collected in April 2022. Risk factors associated with dairy farms’ SCC and TPC were investigated using multivariable population-averaged generalized estimating equations (GEE) models. The mean geometric SCC and TPC from these farms were 529,665 cells/mL of milk and 474,492 cfu/mL of milk, respectively. Five risk factors including manure removal frequency, receiving mastitis treatment training, washing the udder using soap, number of workers, and ownership of the pasture area were associated with SCC. Two risk factors, manure removal frequency and dairy income contribution, were associated with TPC. These findings can therefore be used as a starting point to improve udder health and milk quality in Indonesia and other countries where smallholder farmers play a significant role in milk production.

Published
2023
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15. Fluid Mixing during Phase Separation in Crystallizing White Dwarfs

Author

M. H. Montgomery and Bart H. Dunlap

Subjects
White dwarf stars, Stellar magnetic fields, Stellar interiors, Stellar oscillations, Stellar physics, Stellar convective zones, Astrophysics, QB460-466
Abstract

Accurate models of cooling white dwarfs must treat the energy released as their cores crystallize. This phase transition slows the cooling by releasing latent heat and also gravitational energy, which results from phase separation: liquid C is released from the solid C/O core, driving an outward carbon flux. The Gaia color–magnitude diagram provides striking confirmation of this theory by revealing a mass-dependent overdensity of white dwarfs, indicating slowed cooling at the expected location. However, the observed overdensity is enhanced relative to the models. Additionally, it is associated with increased magnetism, suggesting a link between crystallization and magnetic field generation. Recent works aimed at explaining an enhanced cooling delay and magnetic field generation employ a uniform mixing prescription that assumes large-scale turbulent motions; we show here that these calculations are not self-consistent. We also show that thermohaline mixing is most likely efficient enough to provide the required chemical redistribution during C/O phase separation, and that the resulting velocities and mixing lengths are much smaller than previous estimates. These reduced fluid motions cannot generate measurable magnetic fields, suggesting any link with crystallization needs to invoke a separate mechanism. Finally, this mixing alters the chemical profiles, which in turn affects the frequencies of the pulsation modes.

Published
2024
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16. Core crystallization and pile-up in the cooling sequence of evolving white dwarfs

Author

Tremblay, Pier-Emmanuel, Fontaine, Gilles, Fusillo, Nicola Pietro Gentile, Dunlap, Bart H., Gänsicke, Boris T., Hollands, Mark A., Hermes, J. J., Marsh, Thomas R., Cukanovaite, Elena, and Cunningham, Tim

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

White dwarfs are stellar embers depleted of nuclear energy sources that cool over billions of years. These stars, which are supported by electron degeneracy pressure, reach densities of 1e7 grams per cubic centimetre in their cores. It has been predicted that a first-order phase transition occurs during white-dwarf cooling, leading to the crystallization of the non-degenerate carbon and oxygen ions in the core, which releases a considerable amount of latent heat and delays the cooling process by about one billion years. However, no direct observational evidence of this effect has been reported so far. Here we report the presence of a pile-up in the cooling sequence of evolving white dwarfs within 100 parsecs of the Sun, determined using photometry and parallax data from the Gaia satellite. Using modelling, we infer that this pile-up arises from the release of latent heat as the cores of the white dwarfs crystallize. In addition to the release of latent heat, we find strong evidence that cooling is further slowed by the liberation of gravitational energy from element sedimentation in the crystallizing cores. Our results describe the energy released by crystallization in strongly coupled Coulomb plasmas, and the measured cooling delays could help to improve the accuracy of methods used to determine the age of stellar populations from white dwarfs., Comment: 17 pages, author accepted version. Published in Nature 9 January 2019

Published
2019
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21. Influence of different data-averaging methods on mean values of selected variables derived from preoperative cardiopulmonary exercise testing in patients scheduled for colorectal surgery.

Author

Ruud F W Franssen, Bart H E Sanders, Tim Takken, F Jeroen Vogelaar, Maryska L G Janssen-Heijnen, and Bart C Bongers

Subjects
Medicine, Science
Abstract

IntroductionPatients with a low cardiorespiratory fitness (CRF) undergoing colorectal cancer surgery have a high risk for postoperative complications. Cardiopulmonary exercise testing (CPET) to assess CRF is the gold standard for preoperative risk assessment. To aid interpretation of raw breath-by-breath data, different methods of data-averaging can be applied. This study aimed to investigate the influence of different data-averaging intervals on CPET variables used for preoperative risk assessment, as well as to evaluate whether different data-averaging intervals influence preoperative risk assessment.MethodsA total of 21 preoperative CPETs were interpreted by two exercise physiologists using stationary time-based data-averaging intervals of 10, 20, and 30 seconds and rolling average intervals of 3 and 7 breaths. Mean values of CPET variables between different data averaging intervals were compared using repeated measures ANOVA. The variables of interest were oxygen uptake at peak exercise (VO2peak), oxygen uptake at the ventilatory anaerobic threshold (VO2VAT), oxygen uptake efficiency slope (OUES), the ventilatory equivalent for carbon dioxide at the ventilatory anaerobic threshold (VE/VCO2VAT), and the slope of the relationship between the minute ventilation and carbon dioxide production (VE/VCO2-slope).ResultsBetween data-averaging intervals, no statistically significant differences were found in the mean values of CPET variables except for the ventilatory equivalent for carbon dioxide at the ventilatory anaerobic threshold (P = 0.001). No statistically significant differences were found in the proportion of patients classified as high or low risk regardless of the used data-averaging interval.ConclusionThere appears to be no significant or clinically relevant influence of the evaluated data-averaging intervals on the mean values of CPET outcomes used for preoperative risk assessment. Clinicians may choose a data-averaging interval that is appropriate for optimal interpretation and data visualization of the preoperative CPET. Nevertheless, caution should be taken as the chosen data-averaging interval might lead to substantial within-patient variation for individual patients.Clinical trial registrationProspectively registered at ClinicalTrials.gov (NCT05353127).

Published
2023
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24. Ten-year results of a prospective cohort of large-head metal-on-metal total hip arthroplasty: a concise follow-up of a previous report

Author

Christiaan P. van Lingen, Harmen B. Ettema, Bart H. Bosker, and Cees C. P. M. Verheyen

Subjects
metal-on-metal, pseudotumor, revision, total hip arthroplasty, hip replacement, metal ions, large head, surveillance, metal-on-metal total hip arthroplasty, pseudotumours, hips, ct scanning, cobalt, metal, blood, hip prosthesis, infection, osteolysis, Orthopedic surgery, RD701-811
Abstract

Aims: Large-diameter metal-on-metal (MoM) total hip arthroplasty (THA) has demonstrated unexpected high failure rates and pseudotumour formation. The purpose of this prospective cohort study is to report ten-year results in order to establish revision rate, prevalence of pseudotumour formation, and relation with whole blood cobalt levels. Methods: All patients were recalled according to the guidelines of the Dutch Orthopaedic Association. They underwent clinical and radiographical assessments (radiograph and CT scan) of the hip prosthesis and whole blood cobalt ion measurements. Overall, 94 patients (95 hips) fulfilled our requirements for a minimum ten-year follow-up. Results: Mean follow-up was 10.9 years (10 to 12), with a cumulative survival rate of 82.4%. Reason for revision was predominantly pseudotumour formation (68%), apart from loosening, pain, infection, and osteolysis. The prevalence of pseudotumour formation around the prostheses was 41%, while our previous report of this cohort (with a mean follow-up of 3.6 years) revealed a 39% prevalence. The ten-year revision-free survival with pseudotumour was 66.7% and without pseudotumour 92.4% (p < 0.05). There was poor discriminatory ability for cobalt for pseudotumour formation. Conclusion: This prospective study reports a minimum ten-year follow-up of large-head MoM THA. Revision rates are high, with the main reason being the sequelae of pseudotumour formation, which were rarely observed after five years of implantation. Blood ion measurements show limited discriminatory capacity in diagnosing pseudotumour formation. Our results evidence that an early comprehensive follow-up strategy is essential for MoM THA to promptly identify and manage early complications and revise on time. After ten years follow-up, we do not recommend continuing routine CT scanning or whole cobalt blood measurements, but instead enrolling these patients in routine follow-up protocols for THA. Cite this article: Bone Jt Open 2022;3(1):61–67.

Published
2022
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27. The Solar Neighborhood. XXXIX. Parallax Results from the CTIOPI and NOFS Programs: 50 New Members of the 25 Parsec White Dwarf Sample

Author

Subasavage, John P., Jao, Wei-Chun, Henry, Todd J., Harris, Hugh C., Dahn, Conard C., Bergeron, Pierre, Dufour, Patrick, Dunlap, Bart H., Barlow, Brad N., Ianna, Philip A., Lepine, Sebastien, and Margheim, Steven J.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

We present 114 trigonometric parallaxes for 107 nearby white dwarf (WD) systems from both the Cerro Tololo Inter-American Observatory Parallax Investigation (CTIOPI) and the U. S. Naval Observatory Flagstaff Station (NOFS) parallax programs. Of these, 76 parallaxes for 69 systems were measured by the CTIOPI program and 38 parallaxes for as many systems were measured by the NOFS program. A total of 50 systems are confirmed to be within the 25 pc horizon of interest. Coupled with a spectroscopic confirmation of a common proper motion companion to a Hipparcos star within 25 pc as well as confirmation parallax determinations for two WD systems included in the recently released Tycho Gaia Astrometric Solution (TGAS) catalog, we add 53 new systems to the 25 pc WD sample $-$ a 42% increase. Our sample presented here includes four strong candidate halo systems, a new metal-rich DAZ WD, a confirmation of a recently discovered nearby short-period (P = 2.85 hr) double degenerate, a WD with a new astrometric pertubation (long period, unconstrained with our data), and a new triple system where the WD companion main-sequence star has an astrometric perturbation (P $\sim$ 1.6 yr)., Comment: 32 pages, 12 figures. Figure 4 in the manuscript is a representative set of plots - plots for all WDs presented here are available (allfits_photo.pdf, allfits_photo_DQ.pdf, and allfits_photo_DZ.pdf). Accepted for publication in The Astronomical Journal

Published
2017
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28. Seismology of an Ensemble of ZZ Ceti Stars

Author

Clemens, J. C., O'Brien, P. C., Dunlap, Bart H., and Hermes, J. J.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

We combine all the reliably-measured eigenperiods for hot, short-period ZZ Ceti stars onto one diagram and show that it has the features expected from evolutionary and pulsation theory. To make a more detailed comparison with theory we concentrate on a subset of 16 stars for which rotational splitting or other evidence gives clues to the spherical harmonic index (l) of the modes. The suspected l=1 periods in this subset of stars form a pattern of consecutive radial overtones that allow us to conduct ensemble seismology using published theoretical model grids. We find that the best-matching models have hydrogen layer masses most consistent with the canonically thick limit calculated from nuclear burning. We also find that the evolutionary models with masses and temperatures from spectroscopic fits cannot correctly reproduce the periods of the k=1 to 4 mode groups in these stars, and speculate that the mass of the helium layer in the models is too large., Comment: 6 pages, 4 figures. To appear in the ASP Conference Series proceedings of "20th European Workshop Workshop on White Dwarfs" held at the University of Warwick, UK on July 25-29th, 2016

Published
2016

29. Understanding Systematics in ZZ Ceti Model Fitting to Enable Differential Seismology

Author

Fuchs, J. T., Dunlap, Bart H., Clemens, J. C., Meza, J. A., Dennihy, E., and Koester, D.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

We are conducting a large spectroscopic survey of over 130 Southern ZZ Cetis with the Goodman Spectrograph on the SOAR Telescope. Because it employs a single instrument with high UV throughput, this survey will both improve the signal-to-noise of the sample of SDSS ZZ Cetis and provide a uniform dataset for model comparison. We are paying special attention to systematics in the spectral fitting and quantify three of those systematics here. We show that relative positions in the $\log{g}$-$T_{\rm eff}$ plane are consistent for these three systematics., Comment: 6 pages, 4 figures. To appear in the ASP Conference Series proceedings of "20th European Workshop on White Dwarfs," held at the University of Warwick, UK on July 25-29th, 2016

Published
2016

30. Does Stimulating Physical Activity Affect School Performance?

Author

Golsteyn, Bart H. H., Jansen, Maria W. J., Kann, Dave H. H., and Verhagen, Annelore M. C.

Abstract

This paper investigates whether encouraging children to become more physically active in their everyday life affects their primary school performance. We use data from a field quasi-experiment called the Active Living Program, which aimed to increase active modes of transportation to school and active play among 8- to 12-year-olds living in low socioeconomic status (SES) areas in the Netherlands. Difference-in-differences estimations reveal that while the interventions increase time spent on physical activity during school hours, they negatively affect school performance, especially among the worst-performing students. Further analyses reveal that increased restlessness during instruction time is a potential mechanism for this negative effect. Our results suggest that the commonly found positive effects of exercising or participating in sports on educational outcomes may not be generalizable to physical activity in everyday life. Policymakers and educators who seek to increase physical activity in everyday life need to weigh the health and well-being benefits against the probability of increasing inequality in school performance.

Published
2020
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32. Second asymptomatic carotid surgery trial (ACST-2): a randomised comparison of carotid artery stenting versus carotid endarterectomy

Author

Halliday, Alison, Bulbulia, Richard, Bonati, Leo H, Peto, Richard, Pan, Hongchao, Potter, John, Henning Eckstein, Hans, Farrell, Barbara, Flather, Marcus, Mansfield, Averil, Mihaylova, Boby, Rahimi, Kazim, Simpson, David, Thomas, Dafydd, Sandercock, Peter, Gray, Richard, Molyneux, Andrew, Shearman, Cliff P, Rothwell, Peter, Belli, Anna, Herrington, Will, Judge, Parminder, Leopold, Peter, Mafham, Marion, Gough, Michael, Cao, Piergiorgio, MacDonald, Sumaira, Bari, Vasha, Berry, Clive, Bradshaw, S, Brudlo, Wojciech, Clarke, Alison, Chester, Johanna, Cox, Robin, Cradduck-Bamford, Andrea, Fathers, Susan, Gaba, Kamran, Gray, Mo, Hayter, Elizabeth, Holliday, Constance, Kurien, Rijo, Lay, Michael, le Conte, Steffi, McManus, Jessica, Madgwick, Zahra, Morris, Dylan, Munday, Andrew, Pickworth, Sandra, Ostasz, Wiktor, Poorthuis, Michiel, Richards, Sue, Teixeira, Louisa, Tochlin, Sergey, Tully, Lynda, Wallis, Carol, Willet, Monique, Young, Alan, Casana, Renato, Malloggi, Chiara, Odero Jr, Andrea, Silani, Vincenzo, Parati, Gianfranco, Malchiodi, Giuseppe, Malferrari, Giovanni, Strozzi, Francesco, Tusini, Nicola, Vecchiati, Enrico, Coppi, Gioacchino, Lauricella, Antonio, Moratto, Roberto, Silingardi, Roberto, Veronesi, Jessica, Zini, Andrea, Ferrero, Emanuele, Ferri, Michelangelo, Gaggiano, Andrea, Labate, Carmelo, Nessi, Franco, Psacharopulo, Daniele, Viazzo, Andrea, Malacrida, Giovanni, Mazzaccaro, Daniela, Meola, Giovanni, Modafferi, Alfredo, Nano, Giovanni, Occhiuto, Maria Teresa, Righini, Paolo, Stegher, Silvia, Chiarandini, Stefano, Griselli, Filippo, Lepidi, Sandro, Pozzi Mucelli, Fabio, Naccarato, Marcello, D'Oria, Mario, Ziani, Barbara, Stella, Andrea, Dieng, Mortalla, Faggioli, Gianluca, Gargiulo, Mauro, Palermo, Sergio, Pini, Rodolfo, Puddu, Giovanni Maria, Vacirca, Andrea, Angiletta, Domenico, Desantis, Claudio, Marinazzo, Davide, Mastrangelo, Giovanni, Regina, Guido, Pulli, Raffaele, Bianchi, Paolo, Cireni, Lea, Coppi, Elisabetta, Pizzirusso, Rocco, Scalise, Filippo, Sorropago, Giovanni, Tolva, Valerio, Caso, Valeria, Cieri, Enrico, DeRango, Paola, Farchioni, Luca, Isernia, Giacomo, Lenti, Massimo, Parlani, Gian Battista, Pupo, Guglielmo, Pula, Grazia, Simonte, Gioele, Verzini, Fabio, Carimati, Federico, Delodovici, Maria Luisa, Fontana, Federico, Piffaretti, Gabriele, Tozzi, Matteo, Civilini, Efrem, Poletto, Giorgio, Reimers, Bernhard, Praquin, Barbara, Ronchey, Sonia, Capoccia, Laura, Mansour, Wassim, Sbarigia, Enrico, Speziale, Francesco, Sirignano, Pasqualino, Toni, Danilo, Galeotti, Roberto, Gasbarro, Vincenzo, Mascoli, Francesco, Rocca, Tiberio, Tsolaki, Elpiniki, Bernardini, Giulia, DeMarco, Ester, Giaquinta, Alessia, Patti, Francesco, Veroux, Massimiliano, Veroux, Pierfrancesco, Virgilio, Carla, Mangialardi, Nicola, Orrico, Matteo, Di Lazzaro, Vincenzo, Montelione, Nunzio, Spinelli, Francesco, Stilo, Francesco, Cernetti, Carlo, Irsara, Sandro, Maccarrone, Giuseppe, Tonello, Diego, Visonà, Adriana, Zalunardo, Beniamino, Chisci, Emiliano, Michelagnoli, Stefano, Troisi, Nicola, Masato, Maela, Dei Negri, Massimo, Pacchioni, Andrea, Saccà, Salvatore, Amatucci, Giovanni, Cannizzaro, Alfredo, Accrocca, Federico, Ambrogi, Cesare, Barbazza, Renzo, Marcucci, Giustino, Siani, Andrea, Bajardi, Guido, Savettieri, Giovanni, Argentieri, Angelo, Corbetta, Riccardo, Odero, Attilio, Quaretti, Pietro, Thyrion, Federico Z, Cappelli, Alessandro, Benevento, Domenico, De Donato, Gianmarco, Mele, Maria Agnese, Palasciano, Giancarlo, Pieragalli, Daniela, Rossi, Alessandro, Setacci, Carlo, Setacci, Francesco, Palombo, Domenico, Perfumo, Maria Cecilia, Martelli, Edoardo, Paolucci, Aldo, Trimarchi, Santi, Grassi, Viviana, Grimaldi, Luigi, La Rosa, Giuliana, Mirabella, Domenico, Scialabba, Matteo, Sichel, Leonildo, D'Angelo, Costantino L, Fadda, Gian Franco, Kasemi, Holta, Marino, Mario, Burzotta, Francesco, Codispoti, Francesco Alberto, Ferrante, Angela, Tinelli, Giovanni, Tshomba, Yamume, Vincenzoni, Claudio, Amis, Deborah, Anderson, Dawn, Catterson, Martin, Clarke, Mike, Davis, Michelle, Dixit, Anand, Dyker, Alexander, Ford, Gary, Jackson, Ralph, Kappadath, Sreevalsan, Lambert, David, Lees, Tim, Louw, Stephen, McCaslin, James, Parr, Noala, Robson, Rebecca, Stansby, Gerard, Wales, Lucy, Wealleans, Vera, Wilson, Lesley, Wyatt, Michael, Baht, Hardeep, Balogun, Ibrahim, Burger, Ilse, Cosier, Tracy, Cowie, Linda, Gunathilagan, Gunaratnam, Hargroves, David, Insall, Robert, Jones, Sally, Rudenko, Hannah, Schumacher, Natasha, Senaratne, Jawaharlal, Thomas, George, Thomson, Audrey, Webb, Tom, Brown, Ellen, Esisi, Bernard, Mehrzad, Ali, MacSweeney, Shane, McConachie, Norman, Southam, Alison, Sunman, Wayne, Abdul-Hamiq, Ahmed, Bryce, Jenny, Chetter, Ian, Ettles, Duncan, Lakshminarayan, Raghuram, Mitchelson, Kim, Rhymes, Christopher, Robinson, Graham, Scott, Paul, Vickers, Alison, Ashleigh, Ray, Butterfield, Stephen, Gamble, Ed, Ghosh, Jonathan, McCollum, Charles N, Welch, Mark, Welsh, Sarah, Wolowczyk, Leszek, Donnelly, Mary, D'Souza, Stephen, Egun, Anselm A, Gregary, Bindu, Joseph, Thomas, Kelly, Christine, Punekar, Shuja, Rahi, M Asad, Raj, Sonia, Seriki, Dare, Thomson, George, Brown, James, Durairajan, Ragunath, Grunwald, Iris, Guyler, Paul, Harman, Paula, Jakeways, Matthew, Khuoge, Christopher, Kundu, Ashish, Loganathan, Thayalini, Menon, Nisha, Prabakaran, Raji O, Sinha, Devesh, Thompson, Vicky, Tysoe, Sharon, Briley, Dennis, Darby, Chris, Hands, Linda, Howard, Dominic, Kuker, Wilhelm, Schulz, Ursula, Teal, Rachel, Barer, David, Brown, Andrew, Crawford, Susan, Dunlop, Paul, Krishnamurthy, Ramesh, Majmudar, Nikhil, Mitchell, Duncan, Myint, Min P, O'Brien, Richard, O'Connell, Janice, Sattar, Naweed, Vetrivel, Shanmugam, Beard, Jonathan, Cleveland, Trevor, Gaines, Peter, Humphreys, John, Jenkins, Alison, King, Craig, Kusuma, Daniel, Lindert, Ralph, Lonsdale, Robbie, Nair, Raj, Nawaz, Shah, Okhuoya, Faith, Turner, Douglas, Venables, Graham, Dorman, Paul, Hughes, Andrea, Jones, Deborah, Mendelow, David, Rodgers, Helen, Raudoniitis, Aidas, Enevoldson, Peter, Nahser, Hans, O'Brien, Imelda, Torella, Francesco, Watling, Dave, White, Richard, Brown, Pauline, Dutta, Dipankar, Emerson, Lorraine, Hilltout, Paula, Kulkarni, Sachin, Morrison, Jackie, Poskitt, Keith, Slim, Fiona, Smith, Sarah, Tyler, Amanda, Waldron, Joanne, Whyman, Mark, Bajoriene, Milda, Baker, Lucy, Colston, Amanda, Eliot-Jones, Bekky, Gramizadeh, Gita, Lewis-Clarke, Catherine, McCafferty, Laura, Oliver, Deborah, Palmer, Debbie, Patil, Abhijeet, Pegler, Suzannah, Ramadurai, Gopi, Roberts, Aisling, Sargent, Tracey, Siddegowda, Shivaprasad, Singh-Ranger, Ravi, Williams, Akintunde, Williams, Lucy, Windebank, Steve, Zuromskis, Tadas, Alwis, Lanka, Angus, Jane, Asokanathan, Asaipillai, Fornolles, Caroline, Hardy, Diana, Hunte, Sophy, Justin, Frances, Phiri, Duke, Mitabouana-Kibou, Marie, Sekaran, Lakshmanan, Sethuraman, Sakthivel, Tate, Margaret L, Akyea-Mensah, Joyce, Ball, Stephen, Chrisopoulou, Angela, Keene, Elizabeth, Phair, Alison, Rogers, Steven, Smyth, John V, Bicknell, Colin, Chataway, Jeremy, Cheshire, Nicholas, Clifton, Andrew, Eley, Caroline, Gibbs, Richard, Hamady, Mohammad, Hazel, Beth, James, Alex, Jenkins, Michael, Khanom, Nyma, Lacey, Austin, Mireskandari, Maz, O'Reilly, Joanna, Pereira, Antony, Sachs, Tina, Wolfe, John, Davey, Philip, Rogers, Gill, Smith, Gemma, Tervit, Gareth, Nichol, Ian, Parry, Andrew, Young, Gavin, Ashley, Simon, Barwell, James, Dix, Francis, Nor, Azlisham M, Parry, Chris, Birt, Angela, Davies, Paul, George, Jim, Graham, Anne, Jonker, Leon, Kelsall, Nicci, Potts, Caroline, Wilson, Toni, Crinnion, Jamie, Cuenoud, Larissa, Aleksic, Nikola, Babic, Srdan, Ilijevski, Nenad, Radak, Đorde, Sagic, Dragan, Tanaskovic, Slobodan, Colic, Momcilo, Cvetic, Vladimir, Davidovic, Lazar, Jovanovic, Dejana R, Koncar, Igor, Mutavdžic, Perica, Sladojevic, Miloš, Tomic, Ivan, Debus, Eike S, Grzyska, Ulrich, Otto, Dagmar, Thomalla, Götz, Barlinn, Jessica, Gerber, Johannes, Haase, Kathrin, Hartmann, Christian, Ludwig, Stefan, Pütz, Volker, Reeps, Christian, Schmidt, Christine, Weiss, Norbert, Werth, Sebastian, Winzer, Simon, Gemper, Janine, Günther, Albrecht, Heiling, Bianka, Jochmann, Elisabeth, Karvouniari, Panagiota, Klingner, Carsten, Mayer, Thomas, Schubert, Julia, Schulze-Hartung, Friederike, Zanow, Jürgen, Bausback, Yvonne, Borger, Franka, Botsios, Spiridon, Branzan, Daniela, Bräunlich, Sven, Hölzer, Henryk, Lenzer, Janin, Piorkowski, Christopher, Richter, Nadine, Schuster, Johannes, Scheinert, Dierk, Schmidt, Andrej, Staab, Holger, Ulrich, Matthias, Werner, Martin, Berger, Hermann, Biró, Gábor, Eckstein, Hans-Henning, Kallmayer, Michael, Kreiser, Kornelia, Zimmermann, Alexander, Berekoven, Bärbel, Frerker, Klaus, Gordon, Vera, Torsello, Giovanni, Arnold, Sebastian, Dienel, Cora, Storck, Martin, Biermaier, Bernhard, Gissler, Hans Martin, Klötzsch, Christof, Pfeiffer, Tomas, Schneider, Ralph, Söhl, Leander, Wennrich, Michael, Alonso, Angelika, Keese, Michael, Groden, Christoph, Cöster, Andreas, Engelhardt, Andreas, Ratusinski, Christoph-Maria, Berg, Bengt, Delle, Martin, Formgren, Johan, Gillgren, Peter, Jarl, Lotta, Kall, Torbjörn B, Konrad, Peter, Nyman, Niklas, Skiöldebrand, Claes, Steuer, Johnny, Takolander, Rabbe, Malmstedt, Jonas, Acosta, Stefan, Björses, Katarina, Brandt, Kerstin, Dias, Nuno, Gottsäter, Anders, Holst, Jan, Kristmundsson, Thorarinn, Kühme, Tobias, Kölbel, Tilo, Lindblad, Bengt, Lindh, Mats, Malina, Martin, Ohrlander, Tomas, Resch, Tim, Rönnle, Viola, Sonesson, Björn, Warvsten, Margareta, Zdanowski, Zbigniew, Campbell, Erik, Kjellin, Per, Lindgren, Hans, Nyberg, Johan, Petersen, Björn, Plate, Gunnar, Pärsson, Håkan, Qvarfordt, Peter, Ignatenko, Pavel, Karpenko, Andrey, Starodubtsev, Vladimir, Chernyavsky, Mikhail A, Golovkova, Maria S, Komakha, Boris B, Zherdev, Nikolay N, Belyasnik, Andrey, Chechulov, Pavel, Kandyba, Dmitry, Stepanishchev, Igor, Csobay-Novák, Csaba, Dósa, Edit, Entz, László, Nemes, Balázs, Szeberin, Zoltán, Barzó, Pál, Bodosi, Mihaly, Fákó, Eniko, Fülöp, Béla, Németh, Tamás, Pazdernyik, Szilárd, Skoba, Krisztina, Vörös, Erika, Chatzinikou, Eleni, Giannoukas, Athanasios, Karathanos, Christos, Koutsias, Stylianos, Kouvelos, Georgios, Matsagkas, Miltiadis, Ralli, Styliani, Rountas, Christos, Rousas, Nikolaos, Spanos, Konstantinos, Brountzos, Elias, Kakisis, John D, Lazaris, Andreas, Moulakakis, Konstantinos G, Stefanis, Leonidas, Tsivgoulis, Georgios, Vasdekis, Spyros, Antonopoulos, Constantine N, Bellenis, Ion, Maras, Dimitrios, Polydorou, Antonios, Polydorou, Victoria, Tavernarakis, Antonios, Ioannou, Nikolaos, Terzoudi, Maria, Lazarides, Miltos, Mantatzis, Michalis, Vadikolias, Kostas, Dzieciuchowicz, Lukasz, Gabriel, Marcin, Krasinski, Zbigniew, Oszkinis, Grzegorz, Pukacki, Fryderyk, Slowinski, Maciej, Stanišic, Michal-Goran, Staniszewski, Ryszard, Tomczak, Jolanta, Zielinski, Maciej, Myrcha, Piotr, Rózanski, Dorota, Drelichowski, Stanislaw, Iwanowski, Wojciech, Koncewicz, Katarzyna, Bialek, Pawel, Biejat, Zbigniew, Czepel, Wojciech, Czlonkowska, Anna, Dowzenko, Anatol, Jedrzejewska, Julia, Kobayashi, Adam, Leszczynski, Jerzy, Malek, Andrzej, Polanski, Jerzy, Proczka, Robert, Skorski, Maciej, Szostek, Mieczyslaw, Andziak, Piotr, Dratwicki, Maciej, Gil, Robert, Nowicki, Miroslaw, Pniewski, Jaroslaw, Rzezak, Jaroslaw, Seweryniak, Piotr, Dabek, Pawel, Juszynski, Michal, Madycki, Grzegorz, Pacewski, Bartosz, Raciborski, Witold, Slowinski, Piotr, Staszkiewicz, Walerian, Bombic, Martin, Chlouba, Vladimír, Fiedler, Jirí, Hes, Karel, Koštál, Petr, Sova, Jindrich, Kríž, Zdenek, Prívara, Mojmír, Reif, Michal, Staffa, Robert, Vlachovský, Robert, Vojtíšek, Bohuslav, Hrbác, Tomáš, Kuliha, Martin, Procházka, Václav, Roubec, Martin, Školoudík, David, Netuka, David, Šteklácová, Anna, Beneš III, Vladimír, Buchvald, Pavel, Endrych, Ladislav, Šercl, Miroslav, Campos Jr, Walter, Casella, Ivan B, de Luccia, Nelson, Estenssoro, André E V, Presti, Calógero, Puech-Leão, Pedro, Neves, Celso R B, da Silva, Erasmo S, Sitrângulo Jr, Cid J, Monteiro, José A T, Tinone, Gisela, Bellini Dalio, Marcelo, Joviliano, Edwaldo E, Pontes Neto, Octávio M, Serra Ribeiro, Mauricio, Cras, Patrick, Hendriks, Jeroen M H, Hoppenbrouwers, Mieke, Lauwers, Patrick, Loos, Caroline, Yperzeele, Laetitia, Geenens, Mia, Hemelsoet, Dimitri, van Herzeele, Isabelle, Vermassen, Frank, Astarci, Parla, Hammer, Frank, Lacroix, Valérie, Peeters, André, Verhelst, Robert, Cirelli, Silvana, Dormal, Pol, Grimonprez, Annelies, Lambrecht, Bart, Lerut, Philipe, Thues, Eddy, De Koster, Guy, Desiron, Quentin, Maertens de Noordhout, Alain, Malmendier, Danielle, Massoz, Mireille, Saad, Georges, Bosiers, Marc, Callaert, Joren, Deloose, Koen, Blanco Cañibano, Estrella, García Fresnillo, Beatriz, Guerra Requena, Mercedes, Morata Barrado, Pilar C, Muela Méndez, Miguel, Yusta Izquierdo, Antonio, Aparici Robles, Fernando, Blanes Orti, Paula, García Dominguez, Luis, Martínez López, Rafael, Miralles Hernández, Manuel, Tembl Ferrairo, José I, Chamorro, Ángel, Macho, Juan, Obach, Víctor, Riambau, Vincent, San Román, Luis, Ahlhelm, Frank J, Blackham, Kristine, Engelter, Stefan, Eugster, Thomas, Gensicke, Henrik, Gürke, Lorenz, Lyrer, Philippe, Mariani, Luigi, Maurer, Marina, Mujagic, Edin, Müller, Mandy, Psychogios, Marios, Stierli, Peter, Stippich, Christoph, Traenka, Christopher, Wolff, Thomas, Wagner, Benjamin, Wiegert, Martina M, Clarke, Sandra, Diepers, Michael, Gröchenig, Ernst, Gruber, Philipp, Isaak, Andrej, Kahles, Timo, Marti, Regula, Nedeltchev, Krassen, Remonda, Luca, Tissira, Nadir, Valença Falcão, Martina, de Borst, Gert J, Lo, Rob H, Moll, Frans L, Toorop, Raechel, van der Worp, Bart H, Vonken, Evert J, Kappelle, Jaap L, Jahrome, Ommid, Vos, Floris, Schuiling, Wouter, van Overhagen, Hendrik, Keunen, Rudolf W M, Knippenberg, Bob, Wever, Jan J, Lardenoije, Jan W, Reijnen, Michel, Smeets, Luuk, van Sterkenburg, Steven, Fraedrich, Gustav, Gizewski, Elke, Gruber, Ingrid, Knoflach, Michael, Kiechl, Stefan, Rantner, Barbara, Abdulamit, Timur, Bergeron, Patrice, Padovani, Raymond, Trastour, Jean-Christophe, Cardon, Jean-Marie, Le Gallou-Wittenberg, Anne, Allaire, Eric, Becquemin, Jean-Pierre, Cochennec-Paliwoda, Frédéric, Desgranges, Pascal, Hosseini, Hassan, Kobeiter, Hicham, Marzelle, Jean, Almekhlafi, Mohammed A, Bal, Simerpreet, Barber, Phillip A, Coutts, Shelagh B, Demchuk, Andrew M, Eesa, Muneer, Gillies, Michelle, Goyal, Mayank, Hill, Michael D, Hudon, Mark E, Jambula, Anitha, Kenney, Carol, Klein, Gary, McClelland, Marie, Mitha, Alim, Menon, Bijoy K, Morrish, William F, Peters, Steven, Ryckborst, Karla J, Samis, Greg, Save, Supriya, Smith, Eric E, Stys, Peter, Subramaniam, Suresh, Sutherland, Garnette R, Watson, Tim, Wong, John H, Zimmel, L, Flis, Vojko, Matela, Jože, Miksic, Kazimir, Milotic, Franko, Mrdja, Božidar, Stirn, Barbara, Tetickovic, Erih, Gasparini, Mladen, Grad, Anton, Kompara, Ingrid, Miloševic, Zoren, Palmiste, Veronika, Toomsoo, Toomas, Aidashova, Balzhan, Kospanov, Nursultan, Lyssenko, Roman, Mussagaliev, Daulet, Beyar, Rafi, Hoffman, Aaron, Karram, Tony, Kerner, Arthur, Nikolsky, Eugenia, Nitecki, Samy, Andonova, Silva, Bachvarov, Chavdar, Petrov, Vesko, Cvjetko, Ivan, Vidjak, Vinko, Halužan, Damir, Petrunic, Mladen, Liu, Bao, Liu, Chang-Wei, Bartko, Daniel, Beno, Peter, Rusnák, František, Zelenák, Kamil, Ezura, Masayuki, Inoue, Takashi, Kimura, Naoto, Kondo, Ryushi, Matsumoto, Yasushi, Shimizu, Hiroaki, Endo, Hidenori, Furui, Eisuke, Bakke, Søren, Krohg-Sørensen, Kristen, Nome, Terje, Skjelland, Mona, Tennøe, Bjørn, Albuquerque e Castro, João, Alves, Gonçalo, Bastos Gonçalves, Frederico, de Aragão Morais, José, Garcia, Ana C, Valentim, Hugo, Vasconcelos, Leonor, Belcastro, Fernando, Cura, Fernando, Zaefferer, Patricio, Abd-Allah, Foad, Eldessoki, Mohamed H, Heshmat Kassem, Hussein, Soliman Gharieb, Haytham, Colgan, Mary P, Haider, Syed N, Harbison, Joe, Madhavan, Prakash, Moore, Dermot, Shanik, Gregor, Kazan, Viviane, Nazzal, Munier, and Ramsey-Williams, Vicki

Published
2021
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36. The Magnetic Cataclysmic Variable LSQ1725-64

Author

Fuchs, J. T., Dunlap, Bart H., Dennihy, E., O'Donoghue, D., Clemens, J. C., Reichart, D. E., Moore, J. P., LaCluyze, A. P., Haislip, J. B., and Ivarsen, K. V.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

We present new photometry and spectroscopy of the 94m eclipsing binary LSQ1725-64 that provide insight into the fundamental parameters and evolutionary state of this system. We confirm that LSQ1725-64 is a magnetic cataclysmic variable whose white dwarf has a surface-averaged magnetic field strength of $12.5 \pm 0.5$ MG measured from Zeeman splitting. The spectral type and colour of the secondary, as well as the eclipse length, are consistent with other secondaries that have not yet evolved through the period minimum expected for cataclysmic variables. We observe two different states of mass transfer and measure the transition between the two to occur over about 45 orbital cycles. In the low state, we observe photometric variations that we hypothesize to arise predominantly from two previously heated magnetic poles of the white dwarf. Our precise eclipse measurements allow us to determine binary parameters of LSQ1725-64 and we find it contains a high mass ($0.97 \pm 0.03\ M_{\odot}$) white dwarf if we assume a typical mass-radius relationship for a CO core white dwarf. We also measure an eclipse of the accretion stream after the white dwarf eclipse, and use it to estimate an upper limit of the mass transfer rate. This derived limit is consistent with that expected from angular momentum loss via gravitational radiation alone., Comment: Accepted to MNRAS, 16 pages, 12 figures

Published
2016
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37. Experimental Validation of a Microscopic Ellipsoidal Particle Model Immersed in Fluid Flow

Author

Meurer, A., Weber, A., Bart, H. -J., and Klar, A.

Subjects
Physics - Fluid Dynamics, Condensed Matter - Soft Condensed Matter, Mathematics - Dynamical Systems
Abstract

A simulation of ellipsoidal particles inside a fluid flow is presented and validated from our own lab size experiments where data has been recorded using a camera set-up and post-processing of the pictures. The model is based on Jeffery's equation, where the orientation and position of the particles are influenced by the surrounding fluid. Additionally, particle-particle interaction and particle-wall interaction are taken into account.

Published
2016

38. The Prognostic Relevance of MRI Characteristics in Myxofibrosarcoma Patients Treated with Neoadjuvant Radiotherapy

Author

Stefan G. van Ravensteijn, Maikel J. L. Nederkoorn, Tom C. P. Wal, Yvonne M. H. Versleijen-Jonkers, Pètra M. Braam, Uta E. Flucke, Johannes J. Bonenkamp, Bart H. W. Schreuder, Carla M. L. van Herpen, Johannes H. W. de Wilt, Ingrid M. E. Desar, and Jacky W. J. de Rooy

Subjects
myxofibrosarcoma, neoadjuvant radiotherapy, magnetic resonance imaging, prognostic factors, local recurrence, tail sign, Neoplasms. Tumors. Oncology. Including cancer and carcinogens, RC254-282
Abstract

To improve local control, neoadjuvant radiotherapy (nRT) followed by surgery is the standard of care in myxofibrosarcoma (MFS) because of its infiltrative growth pattern. Nevertheless, local recurrence rates are high. Data on prognostic factors for poor clinical outcomes are lacking. This retrospective study thus investigates the prognostic relevance of magnetic resonance imaging (MRI) characteristics before and after nRT in 40 MFS patients, as well as their association with disease-free survival (DFS) and overall survival (OS). A vascular pedicle, defined as extra-tumoral vessels at the tumor periphery, was observed in 12 patients (30.0%) pre-nRT and remained present post-nRT in all cases. Patients with a vascular pedicle had worse DFS (HR 5.85; 95% CI 1.56–21.90; p = 0.009) and OS (HR 9.58; 95% CI 1.91–48.00; p = 0.006). An infiltrative growth pattern, referred to as a tail sign, was observed in 22 patients (55.0%) pre-nRT and in 19 patients (47.5%) post-nRT, and was associated with worse DFS post-nRT (HR 6.99; 95% CI 1.39–35.35; p = 0.019). The percentage of tumor necrosis estimated by MRI was increased post-nRT, but was not associated with survival outcomes. The presence of a tail sign or vascular pedicle on MRI could support the identification of patients at risk for poor clinical outcomes after nRT.

Published
2023
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41. Utilisation of sexual and reproductive health services among street children and young adults in Kampala, Uganda: does migration matter?

Author

Mulekya F. Bwambale, Paul Bukuluki, Cheryl A. Moyer, and Bart H. W. Van den Borne

Subjects
Rural–urban migration, Street children and young adults, Sexual and reproductive health services, Uganda, Public aspects of medicine, RA1-1270
Abstract

Abstract Background While the nexus of migration and health outcomes is well acknowledged, the effect of rural–urban migration on the use of sexual and reproductive health (SRH) services has received less attention. We assessed the effect of rural–urban migration on the use of SRH services, while controlling for confounding, and whether there is a difference in the use of SRH services among migrant and non-migrant street children and young adults. Methods Data were collected from 513 street children and young adults aged 12–24 years, using venue-based time-space sampling (VBTS). We performed multivariate logistic regression analysis using Stata 16.0 to identify factors associated with SRH services use, with rural–urban migration status as the main predictor. Participants were further classified as new migrants (≤ 2 years of stay in city), established migrants (> 2 years of stay in city) or non-migrants (lifelong native street children) with no rural–urban migration history. Results Overall, 18.13% of the street children and young adults had used contraception/family planning, 58.67% had tested for human immunodeficiency virus (HIV) and knew their status and 34.70% had been screened for sexually transmitted infections (STIs). Non-migrants were 2.70 times more likely to use SRH services (HIV testing, STI screening and family planning) compared to the migrants (aOR = 2.70, 95% CI 1.23–5.97). Other factors associated with SRH services use among street children and young adults include age (aOR = 4.70, 95% CI 2.87–7.68), schooling status (aOR = 0.33, 95% CI 0.15–0.76), knowledge of place of care (aOR = 2.71, 95% CI 1.64–4.46) and access to SRH information (aOR = 3.23, 95% CI 2.00–5.24). Conclusions SRH services utilisation among migrant street children and young adults is low compared to their non-migrant counterparts and is independently associated with migration status, age, schooling status, knowledge of place of care and access to SRH information. Our findings call for the need to design and implement multi-dimensional interventions to increase the use of SRH services among street children and young adults, while taking into consideration their migration patterns.

Published
2021
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42. Flat-Panel Mechanical Beam Steerable Array Antennas With In-Plane Rotations: Theory, Design and Low-Cost Implementation

Author

Qi Tang, Bart H. Mcguyer, Eric Booen, Srishti Saraswat, Farbod Tabatabai, Hamid Bolandhemmat, Curt Von Badinski, and Wilhelmus H. Theunissen

Subjects
Beam steering, design-to-cost, flat-panel, high altitude platform, low earth orbit satellites, mechanical systems, Telecommunication, TK5101-6720
Abstract

We present a compact, flat-panel phased-array antenna design that beam steers using only mechanical in-plane rotations. We explain the steering mechanism and characterize the beam analytically and numerically. Measurements of two prototype antennas for different frequencies validate the concept and modeling. The prototype designs are described in detail and feature added phase-offset control of the array elements in the aperture layout. Potential applications include low-cost and low-power flat-panel user terminals for the next generation of aerial and space communication systems.

Published
2021
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43. Sleep classification from wrist-worn accelerometer data using random forests

Author

Kalaivani Sundararajan, Sonja Georgievska, Bart H. W. te Lindert, Philip R. Gehrman, Jennifer Ramautar, Diego R. Mazzotti, Séverine Sabia, Michael N. Weedon, Eus J. W. van Someren, Lars Ridder, Jian Wang, and Vincent T. van Hees

Subjects
Medicine, Science
Abstract

Abstract Accurate and low-cost sleep measurement tools are needed in both clinical and epidemiological research. To this end, wearable accelerometers are widely used as they are both low in price and provide reasonably accurate estimates of movement. Techniques to classify sleep from the high-resolution accelerometer data primarily rely on heuristic algorithms. In this paper, we explore the potential of detecting sleep using Random forests. Models were trained using data from three different studies where 134 adult participants (70 with sleep disorder and 64 good healthy sleepers) wore an accelerometer on their wrist during a one-night polysomnography recording in the clinic. The Random forests were able to distinguish sleep-wake states with an F1 score of 73.93% on a previously unseen test set of 24 participants. Detecting when the accelerometer is not worn was also successful using machine learning ( $$\hbox {F1-score} > 93.31\%$$ F1-score > 93.31 % ), and when combined with our sleep detection models on day-time data provide a sleep estimate that is correlated with self-reported habitual nap behaviour ( $$\hbox {r}=.60$$ r = . 60 ). These Random forest models have been made open-source to aid further research. In line with literature, sleep stage classification turned out to be difficult using only accelerometer data.

Published
2021
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44. Thermometry via Light Shifts in Optical Lattices

Author

McDonald, Mickey, McGuyer, Bart H., Iwata, Geoffrey Z., and Zelevinsky, Tanya

Subjects
Physics - Atomic Physics, Condensed Matter - Quantum Gases, Quantum Physics
Abstract

For atoms or molecules in optical lattices, conventional thermometry methods are often unsuitable due to low particle numbers or a lack of cycling transitions. However, a differential spectroscopic light shift can map temperature onto the line shape with a low sensitivity to trap anharmonicity. We study narrow molecular transitions to demonstrate precise frequency-based lattice thermometry, as well as carrier cooling. This approach should be applicable down to nanokelvin temperatures. We also discuss how the thermal light shift can affect the accuracy of optical lattice clocks., Comment: 7 pages, 4 figures. Final version

Published
2014
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45. Visible optical beats at the hertz level

Author

McDonald, Mickey, Ha, Jiyoun, McGuyer, Bart H., and Zelevinsky, Tanya

Subjects
Physics - Optics, Physics - Physics Education
Abstract

We present a lecture demonstration which produces a visible, beating interference pattern that is the optical analog of demonstrations which produce audible, beating sound-wave interference. The setup is a compact, portable Mach-Zehnder interferometer made of optical components commonly found in laser physics labs. This apparatus may also be built and used in advanced laboratory courses to illustrate concepts in interferometry and laser light modulation., Comment: 6 pages, 2 figures, accepted for publication in the American Journal of Physics

Published
2014
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46. One-Stage Synovectomies Result in Improved Short-Term Outcomes Compared to Two-Stage Synovectomies of Diffuse-Type Tenosynovial Giant Cell Tumor (D-TGCT) of the Knee: A Multicenter, Retrospective, Cohort Study

Author

Geert Spierenburg, Floortje G. M. Verspoor, Jay S. Wunder, Anthony M. Griffin, Peter C. Ferguson, Matthew T. Houdek, David M. King, Richard Boyle, Robert Lor Randall, Steven W. Thorpe, Jacob I. Priester, Erik J. Geiger, Lizz van der Heijden, Nicholas M. Bernthal, Bart H. W. B. Schreuder, Hans Gelderblom, and Michiel A. J. van de Sande

Subjects
tenosynovial giant cell tumor, TGCT, diffuse-type, knee, synovectomy, one-stage, Neoplasms. Tumors. Oncology. Including cancer and carcinogens, RC254-282
Abstract

Diffuse-type tenosynovial giant cell tumors’ (D-TGCTs) intra- and extra-articular expansion about the knee often necessitates an anterior and posterior surgical approach to facilitate an extensive synovectomy. There is no consensus on whether two-sided synovectomies should be performed in one or two stages. This retrospective study included 191 D-TGCT patients from nine sarcoma centers worldwide to compare the postoperative short-term outcomes between both treatments. Secondary outcomes were rates of radiological progression and subsequent treatments. Between 2000 and 2020, 117 patients underwent one-stage and 74 patients underwent two-stage synovectomies. The maximum range of motion achieved within one year postoperatively was similar (flexion 123–120°, p = 0.109; extension 0°, p = 0.093). Patients undergoing two-stage synovectomies stayed longer in the hospital (6 vs. 4 days, p < 0.0001). Complications occurred more often after two-stage synovectomies, although this was not statistically different (36% vs. 24%, p = 0.095). Patients treated with two-stage synovectomies exhibited more radiological progression and required subsequent treatments more often than patients treated with one-stage synovectomies (52% vs. 37%, p = 0.036) (54% vs. 34%, p = 0.007). In conclusion, D-TGCT of the knee requiring two-side synovectomies should be treated by one-stage synovectomies if feasible, since patients achieve a similar range of motion, do not have more complications, but stay for a shorter time in the hospital.

Published
2023
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