1,498 research outputs found
Renormalized Kaluza-Klein theories
Using six-dimensional quantum electrodynamics () as an example we
study the one-loop renormalization of the theory both from the six and
four-dimensional points of view. Our main conclusion is that the properly
renormalized four dimensional theory never forgets its higher dimensional
origin. In particular, the coefficients of the neccessary extra counterterms in
the four dimensional theory are determined in a precise way. We check our
results by studying the reduction of on a two-torus.Comment: LaTeX, 36 pages. A new section added; references improved, typos
fixe
Potential benefits of an adaptive forward collision warning system
Forward collision warning (FCW) systems can reduce rear-end vehicle collisions. However, if the presentation of warnings is perceived as mistimed, trust in the system is diminished and drivers become less likely to respond appropriately. In this driving simulator investigation, 45 drivers experienced two FCW systems: a non-adaptive and an adaptive FCW that adjusted the timing of its alarms according to each individual driver’s reaction time. Whilst all drivers benefited in terms of improved safety from both FCW systems, non-aggressive drivers (low sensation seeking, long followers) did not display a preference to the adaptive FCW over its non-adaptive equivalent. Furthermore, there was little evidence to suggest that the non-aggressive drivers’ performance differed with either system. Benefits of the adaptive system were demonstrated for aggressive drivers (high sensation seeking, short followers). Even though both systems reduced their likelihood of a crash to a similar extent, the aggressive drivers rated each FCW more poorly than their non-aggressive contemporaries. However, this group, with their greater risk of involvement in rear-end collisions, reported a preference for the adaptive system as they found it less irritating and stress-inducing. Achieving greater acceptance and hence likely use of a real system is fundamental to good quality FCW design
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Dislocation Density-Dependent Quality Factors in InGaN Quantum Dot Containing Microdisks
Microdisks incorporating InGaN quantum dots were fabricated using SiO2 microspheres as a hard mask in conjunction with a photoelectrochemical etch step from a structure containing a sacrificial InGaN/InGaN superlattice. Formation of microdisks from two near-identical structures with differing dislocation densities was carried out and investigated using microphotoluminescence. This confirmed the existence of quantum dots through the presence of resolution limited spectral lines and showed a clear correlation between the resulting modes quality factors and the dislocation densities within the disks. The disks with higher dislocation densities showed up to 80% lower quality factors than the low dislocation density disks.Engineering and Applied Science
Simulation Study for Designing a Dedicated Cardiac TOF-PET System
[EN] The development of dedicated positron emission tomography scanners is an active area of research, especially aiming at the improvement of lesion detection and in support of cancer treatment and management. Recently, dedicated Positron Emission Tomography (PET) systems with different configurations for specific organs have been developed for improving detection effectiveness. Open geometries are always subject to distortion and artifacts in the reconstructed images. Therefore, the aim of this work is to determine the optimal geometry for a novel cardiac PET system that will be developed by our team, and determine the time resolution needed to achieve reasonable image quality for the chosen geometry. The proposed geometries consist of 36 modules. These modules are arranged in two sets of two plates, each one with different configurations. We performed Monte Carlo simulations with different TOF resolutions, in order to test the image quality improvement in each case. Our results show, as expected, that increasing TOF resolution reduces distortion and artifact effects. We can conclude that a TOF resolution of the order of 200 ps is needed to reduce the artifacts, to acceptable levels, generated in the simulated cardiac-PET open geometries.This project has been co-financed by the Spanish Government Grants TEC2016-79884-C2 and RTC-2016-5186-1, by the European Union through the European Regional Development Fund (ERDF) and by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (Grant Agreement No. 695536). The work of V.I. was supported by the Generalitat Valenciana APOSTD/2019/086 fellowship.Oliver-Gil, S.; Moliner, L.; Ilisie, V.; Benlloch Baviera, JM.; Rodríguez-Álvarez, M. (2020). Simulation Study for Designing a Dedicated Cardiac TOF-PET System. Sensors. 20(5):1-16. https://doi.org/10.3390/s20051311S116205Gaemperli, O., & Kaufmann, P. A. (2011). PET and PET/CT in cardiovascular disease. Annals of the New York Academy of Sciences, 1228(1), 109-136. doi:10.1111/j.1749-6632.2011.06030.xThackeray, J. T., & Bengel, F. M. (2018). Molecular Imaging of Myocardial Inflammation With Positron Emission Tomography Post-Ischemia. JACC: Cardiovascular Imaging, 11(9), 1340-1355. doi:10.1016/j.jcmg.2018.05.026Li, Z., Gupte, A. A., Zhang, A., & Hamilton, D. J. (2017). Pet Imaging and its Application in Cardiovascular Diseases. Methodist DeBakey Cardiovascular Journal, 13(1), 29. doi:10.14797/mdcj-13-1-29Juárez-Orozco, L. E., Tio, R. A., Alexanderson, E., Dweck, M., Vliegenthart, R., El Moumni, M., … Slart, R. H. J. A. (2017). Quantitative myocardial perfusion evaluation with positron emission tomography and the risk of cardiovascular events in patients with coronary artery disease: a systematic review of prognostic studies. European Heart Journal - Cardiovascular Imaging, 19(10), 1179-1187. doi:10.1093/ehjci/jex331Schelbert, H. R. (2009). Quantification of Myocardial Blood Flow: What is the Clinical Role? Cardiology Clinics, 27(2), 277-289. doi:10.1016/j.ccl.2008.12.009Knuuti, J., Kajander, S., Mäki, M., & Ukkonen, H. (2009). Quantification of myocardial blood flow will reform the detection of CAD. Journal of Nuclear Cardiology, 16(4), 497-506. doi:10.1007/s12350-009-9101-1Peng, H. (2015). Design study of a cardiac-dedicated PET system. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 779, 39-46. doi:10.1016/j.nima.2015.01.042Gonzalez, A. J., Sanchez, F., & Benlloch, J. M. (2018). Organ-Dedicated Molecular Imaging Systems. IEEE Transactions on Radiation and Plasma Medical Sciences, 2(5), 388-403. doi:10.1109/trpms.2018.2846745Moliner, L., Rodríguez-Alvarez, M. J., Catret, J. V., González, A., Ilisie, V., & Benlloch, J. M. (2019). NEMA Performance Evaluation of CareMiBrain dedicated brain PET and Comparison with the whole-body and dedicated brain PET systems. Scientific Reports, 9(1). doi:10.1038/s41598-019-51898-zAhmed, A. M., Tashima, H., Yoshida, E., Nishikido, F., & Yamaya, T. (2017). Simulation study comparing the helmet-chin PET with a cylindrical PET of the same number of detectors. Physics in Medicine and Biology, 62(11), 4541-4550. doi:10.1088/1361-6560/aa685cCho, Z.-H., Son, Y.-D., Kim, H.-K., Kwon, D.-H., Joo, Y.-H., Ra, J. B., … Kim, Y.-B. (2019). Development of Positron Emission Tomography With Wobbling and Zooming for High Sensitivity and High-Resolution Molecular Imaging. IEEE Transactions on Medical Imaging, 38(12), 2875-2882. doi:10.1109/tmi.2019.2916326Surti, S., & Karp, J. S. (2008). Design considerations for a limited angle, dedicated breast, TOF PET scanner. Physics in Medicine and Biology, 53(11), 2911-2921. doi:10.1088/0031-9155/53/11/010Surti, S., & Karp, J. S. (2016). Advances in time-of-flight PET. Physica Medica, 32(1), 12-22. doi:10.1016/j.ejmp.2015.12.007Grant, A. M., Deller, T. W., Khalighi, M. M., Maramraju, S. H., Delso, G., & Levin, C. S. (2016). NEMA NU 2-2012 performance studies for the SiPM-based ToF-PET component of the GE SIGNA PET/MR system. Medical Physics, 43(5), 2334-2343. doi:10.1118/1.4945416Van Sluis, J., de Jong, J., Schaar, J., Noordzij, W., van Snick, P., Dierckx, R., … Boellaard, R. (2019). Performance Characteristics of the Digital Biograph Vision PET/CT System. Journal of Nuclear Medicine, 60(7), 1031-1036. doi:10.2967/jnumed.118.215418Ito, M., Lee, M. S., & Lee, J. S. (2013). Continuous depth-of-interaction measurement in a single-layer pixelated crystal array using a single-ended readout. Physics in Medicine and Biology, 58(5), 1269-1282. doi:10.1088/0031-9155/58/5/1269Bugalho, R., Di Francesco, A., Ferramacho, L., Leong, C., Niknejad, T., Oliveira, L., … Varela, J. (2018). Experimental results with TOFPET2 ASIC for time-of-flight applications. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 912, 195-198. doi:10.1016/j.nima.2017.11.034Gundacker, S., Auffray, E., Frisch, B., Jarron, P., Knapitsch, A., Meyer, T., … Lecoq, P. (2013). Time of flight positron emission tomography towards 100ps resolution with L(Y)SO: an experimental and theoretical analysis. Journal of Instrumentation, 8(07), P07014-P07014. doi:10.1088/1748-0221/8/07/p07014A Code System for Monte Carlo Simulation of Electron and Photon Transporthttp://www.oecd-nea.org/lists/penelope.htmlStrydhorst, J., & Buvat, I. (2016). Redesign of the GATE PET coincidence sorter. Physics in Medicine and Biology, 61(18), N522-N531. doi:10.1088/0031-9155/61/18/n522Baró, J., Sempau, J., Fernández-Varea, J. M., & Salvat, F. (1995). PENELOPE: An algorithm for Monte Carlo simulation of the penetration and energy loss of electrons and positrons in matter. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 100(1), 31-46. doi:10.1016/0168-583x(95)00349-5Sempau, J., Acosta, E., Baro, J., Fernández-Varea, J. M., & Salvat, F. (1997). An algorithm for Monte Carlo simulation of coupled electron-photon transport. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 132(3), 377-390. doi:10.1016/s0168-583x(97)00414-xSempau, J., Fernández-Varea, J. M., Acosta, E., & Salvat, F. (2003). Experimental benchmarks of the Monte Carlo code penelope. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 207(2), 107-123. doi:10.1016/s0168-583x(03)00453-1Reader, A. J., Ally, S., Bakatselos, F., Manavaki, R., Walledge, R. J., Jeavons, A. P., … Zweit, J. (2002). One-pass list-mode EM algorithm for high-resolution 3-D PET image reconstruction into large arrays. IEEE Transactions on Nuclear Science, 49(3), 693-699. doi:10.1109/tns.2002.1039550Spanoudaki, V. C., & Levin, C. S. (2010). Photo-Detectors for Time of Flight Positron Emission Tomography (ToF-PET). Sensors, 10(11), 10484-10505. doi:10.3390/s101110484Siddon, R. L. (1985). Fast calculation of the exact radiological path for a three-dimensional CT array. Medical Physics, 12(2), 252-255. doi:10.1118/1.595715Vandenberghe, S., Daube-Witherspoon, M. E., Lewitt, R. M., & Karp, J. S. (2006). Fast reconstruction of 3D time-of-flight PET data by axial rebinning and transverse mashing. Physics in Medicine and Biology, 51(6), 1603-1621. doi:10.1088/0031-9155/51/6/017Performance Measurements of Positron Emission Tomographshttps://www.nema.org/Standards/ComplimentaryDocuments/Contents%20and%20Scope%20NEMA%20NU%202%202012.pdfYu, W., & Zeng, L. (2014). A Novel Weighted Total Difference Based Image Reconstruction Algorithm for Few-View Computed Tomography. PLoS ONE, 9(10), e109345. doi:10.1371/journal.pone.0109345Tashima, H., Yamaya, T., Yoshida, E., Kinouchi, S., Watanabe, M., & Tanaka, E. (2012). A single-ring OpenPET enabling PET imaging during radiotherapy. Physics in Medicine and Biology, 57(14), 4705-4718. doi:10.1088/0031-9155/57/14/4705Yamaya, T., Inaniwa, T., Minohara, S., Yoshida, E., Inadama, N., Nishikido, F., … Murayama, H. (2008). A proposal of an open PET geometry. Physics in Medicine and Biology, 53(3), 757-773. doi:10.1088/0031-9155/53/3/015Miyake, K. K., Matsumoto, K., Inoue, M., Nakamoto, Y., Kanao, S., Oishi, T., … Togashi, K. (2014). Performance Evaluation of a New Dedicated Breast PET Scanner Using NEMA NU4-2008 Standards. Journal of Nuclear Medicine, 55(7), 1198-1203. doi:10.2967/jnumed.113.131565Yamamoto, S., Honda, M., Oohashi, T., Shimizu, K., & Senda, M. (2011). Development of a Brain PET System, PET-Hat: A Wearable PET System for Brain Research. IEEE Transactions on Nuclear Science, 58(3), 668-673. doi:10.1109/tns.2011.2105502Garibaldi, F., Capuani, S., Colilli, S., Cosentino, L., Cusanno, F., Leo, R. D., … Tamma, C. (2013). TOPEM: A PET-TOF endorectal probe, compatible with MRI for diagnosis and follow up of prostate cancer. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 702, 13-15. doi:10.1016/j.nima.2012.09.020González-Montoro, A., Sánchez, F., Martí, R., Hernández, L., Aguilar, A., Barberá, J., … González, A. J. (2018). Detector block performance based on a monolithic LYSO crystal using a novel signal multiplexing method. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 912, 372-377. doi:10.1016/j.nima.2017.10.09
Affective responses to high-intensity interval training with continuous and respite music
© 2020 Informa UK Limited, trading as Taylor & Francis Group. Music has been shown to enhance affective responses to continuous exercise, but the most effective application of music during interval exercise is poorly understood. This study examined two contrasting applications of music designed to assuage the decline in pleasure often experienced during high-intensity interval training (HIIT). In a repeated measures crossover design, 18 recreationally active participants (10 men and 8 women; M age = 25.1 ± 5.1 years; M BMI = 23.08 ± 2.01 kg/m 2; M VO2max = 38.82 ± 10.73 ml/kg/min) completed three HIIT sessions (10 x 60 s efforts at 100% Wmax, separated by 75 s recovery) on a cycle ergometer. Participants completed two experimental conditions: respite music (applied only during the recovery periods), continuous music (applied throughout the entire HIIT session); and a no-music control condition. Results indicated that music did not influence affective valence during the work bouts or recovery periods of the HIIT sessions (ps >.05), but that listening to music continuously elicited greater post-task enjoyment (p =.032, d = 0.66) and remembered pleasure (p =.044, d = 0.5). This study is the first to investigate the application of music during a practical HIIT protocol and to compare the effects of respite versus continuous music during interval exercise
Some Properties of the Computable Cross Norm Criterion for Separability
The computable cross norm (CCN) criterion is a new powerful analytical and
computable separability criterion for bipartite quantum states, that is also
known to systematically detect bound entanglement. In certain aspects this
criterion complements the well-known Peres positive partial transpose (PPT)
criterion. In the present paper we study important analytical properties of the
CCN criterion. We show that in contrast to the PPT criterion it is not
sufficient in dimension 2 x 2. In higher dimensions we prove theorems
connecting the fidelity of a quantum state with the CCN criterion. We also
analyze the behaviour of the CCN criterion under local operations and identify
the operations that leave it invariant. It turns out that the CCN criterion is
in general not invariant under local operations.Comment: 7 pages; accepted by Physical Review A; error in Appendix B correcte
Hybrid model using logit and nonparametric methods for predicting micro-entity failure
Following the calls from literature on bankruptcy, a parsimonious hybrid bankruptcy model is developed in this paper by combining parametric and non-parametric approaches.To this end, the variables with the highest predictive power to detect bankruptcy are selected using logistic regression (LR). Subsequently, alternative non-parametric methods (Multilayer Perceptron, Rough Set, and Classification-Regression Trees) are applied, in turn, to firms classified as either “bankrupt” or “not bankrupt”. Our findings show that hybrid models, particularly those combining LR and Multilayer Perceptron, offer better accuracy performance and interpretability and converge faster than each method implemented in isolation. Moreover, the authors demonstrate that the introduction of non-financial and macroeconomic variables complement financial ratios for bankruptcy predictio
Spanish reference values for the Breastfeeding Self-Efficacy Scale-Short Form BSES-SF
Fundamento. Describir los valores de referencia para la versión española de la Escala de Autoeficacia para la Lactancia Materna en su versión reducida (BSES-SF), considerando las diferencias según la experiencia previa en lactancia y la paridad. Metodología. Estudio transversal realizado en cinco hospitales de Alicante y uno de la Región de Murcia, con una muestra accidental de 949 mujeres que ofrecieron lactancia materna en el posparto, sin problemas médicos, propios o del recién nacido, que dificultaran la lactancia. Se obtuvieron datos sociodemográficos, obstétricos y sobre autoeficacia materna para la lactancia mediante la escala BSES-SF. Se calcularon datos de tendencia central, dispersión y percentiles de las puntuaciones de la escala BSES-SF para generar valores de referencia para toda la muestra y según la paridad y experiencia previa. Resultados. El nivel de autoeficacia fue significativamente menor (p<0,001) entre las mujeres primíparas (media =47,67±11,03) o sin experiencia previa (media =47,30±11,18) que entre las multíparas (media =52,87±10,66) o con experiencia anterior (media =53,93±9,93). La puntuación de los percentiles P25 y P75 de la escala BSES-SF fue, respectivamente, para toda la muestra de 42 y 59; para las mujeres sin hijos o sin experiencia previos de 39 y 56; para madres con hijos de 46 y 61; y para las madres con experiencia previa de 47 y 62. Conclusión. Los percentiles específicos obtenidos, según la paridad o la experiencia previa, pueden considerarse como valores de referencia para comparar el nivel de autoeficacia de un caso dado, evaluar intervenciones educativas y planificar intervenciones de apoyo durante el posparto.Background. To describe the reference values for the Spanish version of the Breastfeeding Self-Efficacy Scale-Short Form (BSES-SF), considering the differences according to parity and previous breastfeeding experience. Methods. Cross-sectional study in five hospitals in Alicante and one in Murcia, Spain, in a convenience sample of 949 in-hospital breastfeeding women, with no medical problems in the mothers or newborns hindering breastfeeding. Data on sociodemographic and obstetric variables, and on breastfeeding self-efficacy, using the BSES-SF, were collected. Central tendency, dispersion and percentile data were calculated to generate reference values for the entire sample, and by parity and previous experience. Results. The level of self-efficacy was significantly lower (p<0.001) among primiparous women (mean =47.67±11.03) or those without previous experience (mean =47.30±11.18) than among multiparas (mean =52.87±10.66) or women with previous experience (mean =53.93±9.93). The P25 and P75 percentiles for the BSES-SF were, respectively, 42 and 59 for the entire sample; 39 and 56 for women without children or without previous experience; 46 and 61 for mothers with children; and 47 and 62 for mothers with previous experience. Conclusions. The specific percentiles obtained by parity or previous experience should be considered the reference values for comparing the level of self-efficacy of a given case, and for evaluating educational interventions and planning postpartum support interventions.Este estudio recibió financiación del Ministerio de Ciencia e Innovación (nº de expediente PI09/90899)
Resonantly damped surface and body MHD waves in a solar coronal slab with oblique propagation
The theory of magnetohydrodynamic (MHD) waves in solar coronal slabs in a
zero- configuration and for parallel propagation of waves does not allow
the existence of surface waves. When oblique propagation of perturbations is
considered both surface and body waves are able to propagate. When the
perpendicular wave number is larger than a certain value, the body kink mode
becomes a surface wave. In addition, a sausage surface mode is found below the
internal cut-off frequency. When non-uniformity in the equilibrium is included,
surface and body modes are damped due to resonant absorption. In this paper,
first, a normal-mode analysis is performed and the period, the damping rate,
and the spatial structure of eigenfunctions are obtained. Then, the
time-dependent problem is solved, and the conditions under which one or the
other type of mode is excited are investigated.Comment: 19 pages, 9 figures, accepted for publication in Solar Physic
Educating Health Professionals about Disability: A Review of Interventions
Health professionals need to understand the human rights and health needs of disabled people. This review of evidence on interventions demonstrates that a range of often innovative approaches have been trialled. Lectures by faculty are less effective in changing attitudes than contact with disabled people themselves. Existing examples of good practice need to be scaled up, and better and more long-term evaluations of impact are required
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