693 research outputs found
Arc driver operation for either efficient energy transfer or high-current generator
An investigation is made to establish predictable electric arcs along triggered paths for research purposes, the intended application being the heating of the driver gas of a 1 MJ electrically driven shock tube. Trigger conductors consisting of wires, open tubes, and tubes pressurized with different gases were investigated either on the axis of the arc chamber or spiraled along the chamber walls. Design criteria are presented for successful arc initiation with reproducible voltage-current characteristics. Results are compared with other facilities and several application areas are discussed
Rogue decoherence in the formation of a macroscopic atom-molecule superposition
We theoretically examine two-color photoassociation of a Bose-Einstein
condensate, focusing on the role of rogue decoherence in the formation of
macroscopic atom-molecule superpositions. Rogue dissociation occurs when two
zero-momentum condensate atoms are photoassociated into a molecule, which then
dissociates into a pair of atoms of equal-and-opposite momentum, instead of
dissociating back to the zero-momentum condensate. As a source of decoherence
that may damp quantum correlations in the condensates, rogue dissociation is an
obstacle to the formation of a macroscopic atom-molecule superposition. We
study rogue decoherence in a setup which, without decoherence, yields a
macroscopic atom-molecule superposition, and find that the most favorable
conditions for said superposition are a density ~ 1e12 atoms per cc and
temperature ~ 1e-10.Comment: 10 pages, 4 figures, 46+ references; submitted to PR
Quantum Extremism: Effective Potential and Extremal Paths
The reality and convexity of the effective potential in quantum field
theories has been studied extensively in the context of Euclidean space-time.
It has been shown that canonical and path-integral approaches may yield
different results, thus resolving the `convexity problem'. We discuss the
transferral of these treatments to Minkowskian space-time, which also
necessitates a careful discussion of precisely which field configurations give
the dominant contributions to the path integral. In particular, we study the
effective potential for the N=1 linear sigma model.Comment: 11 pages, 4 figure
HReMAS: Hybrid Real-time Musical Alignment System
[EN] This paper presents a real-time audio-to-score alignment system for musical applications. The aim of these systems is to synchronize a live musical performance with its symbolic representation in a music sheet. We have used as a base our previous real-time alignment system by enhancing it with a traceback stage, a stage used in offline alignment to improve the accuracy of the aligned note. This stage introduces some delay, what forces to assume a trade-off between output delay and alignment accuracy that must be considered in the design of this type of hybrid techniques. We have also improved our former system to execute faster in order to minimize this delay. Other interesting improvements, like identification of silence frames, have also been incorporated to our proposed system.This work has been supported by the "Ministerio de Economia y Competitividad" of Spain and FEDER under Projects TEC2015-67387-C4-{1,2,3}-R.Cabañas-Molero, P.; Cortina-Parajón, R.; Combarro, EF.; Alonso-Jordá, P.; Bris-Peñalver, FJ. (2019). HReMAS: Hybrid Real-time Musical Alignment System. The Journal of Supercomputing. 75(3):1001-1013. https://doi.org/10.1007/s11227-018-2265-1S10011013753Alonso P, Cortina R, Rodríguez-Serrano FJ, Vera-Candeas P, Alonso-González M, Ranilla J (2017) Parallel online time warping for real-time audio-to-score alignment in multi-core systems. J Supercomput 73(1):126–138Alonso P, Vera-Candeas P, Cortina R, Ranilla J (2017) An efficient musical accompaniment parallel system for mobile devices. J Supercomput 73(1):343–353Arzt A (2016) Flexible and robust music tracking. Ph.D. thesis, Johannes Kepler University Linz, Linz, ÖsterreichArzt A, Widmer G, Dixon S (2008) Automatic page turning for musicians via real-time machine listening. In: Proceedings of the 18th European Conference on Artificial Intelligence (ECAI), Amsterdam, pp 241–245Carabias-Orti J, Rodríguez-Serrano F, Vera-Candeas P, Ruiz-Reyes N, Cañadas-Quesada F (2015) An audio to score alignment framework using spectral factorization and dynamic time warping. In: Proceedings of ISMIR, pp 742–748Cont A (2006) Realtime audio to score alignment for polyphonic music instruments, using sparse non-negative constraints and hierarchical HMMs. In: 2006 IEEE International Conference on Acoustics Speech and Signal Processing Proceedings, vol 5. pp V–VCont A, Schwarz D, Schnell N, Raphael C (2007) Evaluation of real-time audio-to-score alignment. In: International Symposium on Music Information Retrieval (ISMIR), ViennaDannenberg RB, Raphael C (2006) Music score alignment and computer accompaniment. Commun ACM 49(8):38–43Devaney J, Ellis D (2009) Handling asynchrony in audio-score alignment. In: Proceedings of the International Computer Music Conference Computer Music Association. pp 29–32Dixon S (2005) An on-line time warping algorithm for tracking musical performances. In: Proceedings of the International Joint Conference on Artificial Intelligence (IJCAI). pp 1727–1728Duan Z, Pardo B (2011) Soundprism: an online system for score-informed source separation of music audio. IEEE J Sel Top Signal Process 5(6):1205–1215Ewert S, Muller M, Grosche P (2009) High resolution audio synchronization using chroma onset features. In: IEEE International Conference on Acoustics, Speech and Signal Processing, 2009 (ICASSP 2009). pp 1869–1872Hu N, Dannenberg R, Tzanetakis G (2003) Polyphonic audio matching and alignment for music retrieval. In: 2003 IEEE Workshop on Applications of Signal Processing to Audio and Acoustics. pp 185–188Kaprykowsky H, Rodet X (2006) Globally optimal short-time dynamic time warping, application to score to audio alignment. In: Proceedings of the International Conference on Acoustics, Speech and Signal Processing, vol 5. pp. V–VLi B, Duan Z (2016) An approach to score following for piano performances with the sustained effect. IEEE/ACM Trans Audio Speech Lang Process 24(12):2425–2438Miron M, Carabias-Orti JJ, Bosch JJ, Gómez E, Janer J (2016) Score-informed source separation for multichannel orchestral recordings. J Electr Comput Eng 2016(8363507):1–19Muñoz-Montoro A, Cabañas-Molero P, Bris-Peñalver F, Combarro E, Cortina R, Alonso P (2017) Discovering the composition of audio files by audio-to-midi alignment. In: Proceedings of the 17th International Conference on Computational and Mathematical Methods in Science and Engineering. pp 1522–1529Orio N, Schwarz D (2001) Alignment of monophonic and polyphonic music to a score. In: Proceedings of the International Computer Music Conference (ICMC), pp 155–158Pätynen J, Pulkki V, Lokki T (2008) Anechoic recording system for symphony orchestra. Acta Acust United Acust 94(6):856–865Raphael C (2010) Music plus one and machine learning. In: Proceedings of the 27th International Conference on Machine Learning (ICML), pp 21–28Rodriguez-Serrano FJ, Carabias-Orti JJ, Vera-Candeas P, Martinez-Munoz D (2016) Tempo driven audio-to-score alignment using spectral decomposition and online dynamic time warping. ACM Trans Intell Syst Technol 8(2):22:1–22:2
The Path-Integral Approach to the N=2 Linear Sigma Model
In QFT the effective potential is an important tool to study symmetry
breaking phenomena. It is known that, in some theories, the canonical approach
and the path-integral approach yield different effective potentials. In this
paper we investigate this for the Euclidean N=2 linear sigma model. Both the
Green's functions and the effective potential will be computed in three
different ways. The relative merits of the various approaches are discussed.Comment: 2 figure
High prevalence of peripheral neuropathy in multiple myeloma patients and the impact of vitamin D levels, a cross-sectional study
Purpose: Peripheral neuropathy (PN) is common in patients with multiple myeloma (MM). We hypothesized that the relationship between hypovitaminosis D and PN described in diabetes mellitus patients may also be present in MM patients. Methods: To study this potential association, we assessed the incidence of hypovitaminosis D (vitamin D < 75 nmol/L [= 30 ng/mL]) in smouldering and active MM patients in two Dutch hospitals. Furthermore, a validated questionnaire was used to distinguish different PN grades. Results: Of the 120 patients included between January 2017 and August 2018, 84% had an inadequate vitamin D level (median vitamin D level 49.5 nmol/L [IQR 34–65 nmol/L]; mean age: 68 years [SD ± 7.7]; males: 58%). PN was reported by 69% of patients (n = 83); however, of these 83 patients, PN was not documented in the medical records of 52%. An association was found between lower vitamin D levels and higher incidence of PN in the total population (P = 0.035), and in the active MM patients (P = 0.016). Conclusion: This multi-centre cohort study showed that PN and hypovitaminosis D are common in MM patients, and addressing low vitamin D levels in the treatment of MM patients might be beneficial in reducing the risk of PN. More attention for PN is warranted, as PN is underreported by clinicians. Further research is needed to fully understand the implications of vitamin D in the development of PN in patients with MM. Clinical trial registration: Netherland Trial Register NL5835, date of registration July 28, 2016
Parkinsonism caused by adverse drug reactions: a case series
<p>Abstract</p> <p>Introduction</p> <p>Parkinsonism puts a high direct cost burden on both patient and caregiver. Several reports of drug-induced parkinsonism have been published, but to the best of our knowledge, there has not been any report of quinine or halothane inducing parkinsonism.</p> <p>Case presentation</p> <p>We describe two cases of parkinsonism possibly caused by adverse drug reaction to quinine in a 29-year-old black Nigerian woman and to halothane in a 36-year-old black Hausa (Nigerian) man who received it as general anaesthesia for appendicectomy in our teaching hospital.</p> <p>Conclusion</p> <p>These are two unusual cases of parkinsonism caused by adverse drug reactions to high-dose quinine and to halothane as general anaesthesia. We consider that these two cases are important in bringing this potential side-effect to the attention of both pharmacologists and primary care physicians as these are two of the most commonly used medications in our clinics. We conclude that parkinsonism should be included among the adverse drug reactions to high-dose quinine and halothane general anaesthetic.</p
Genetic polymorphisms in the cyclooxygenase-2 gene, use of nonsteroidal anti-inflammatory drugs, and breast cancer risk
INTRODUCTION: The association between use of nonsteroidal anti-inflammatory drugs (NSAIDs) and breast cancer risk remains unclear. Inconsistencies in previously reported findings may be partly due to differences in expression of cyclooxygenase (COX)-2. We hypothesized that genetic polymorphisms (COX-2 .926, COX-2 .5209, and COX-2 .8473) may reduce overall breast cancer risk or risk for subtypes of breast cancer by modulating the inflammatory response and may interact with aspirin or any NSAID use. METHODS: We conducted a population-based, case-control study in which we genotyped 1,067 breast cancer cases and 1,110 control individuals included in the Long Island Breast Cancer Study Project. RESULTS: No major effects of the three COX-2 variant alleles on breast cancer risk were found. A total of eight distinct haplotypes and 18 diplotypes were observed in the population. Overall, no significant associations between COX-2 haplotypes/diplotypes and breast cancer risk were observed. Among women who used aspirin or any NSAID there was little evidence for an interaction with the at-risk COX-2 genotypes, with one exception. Among women with hormone receptor positive breast cancer, the reduced risk for any NSAID use was only evident among those who had at least one variant C allele of COX-2 .8473 (odds ratio = 0.7, 95% confidence interval = 0.5 to 1.0; P for the interaction = 0.02). There was no corresponding interaction for aspirin use, possibly because of limited power. CONCLUSION: These data provide modest evidence that the C allele of COX-2 .8473 may interact with NSAIDs to reduce risk for hormone receptor positive breast cancer
First search for gravitational waves from the youngest known neutron star
We present a search for periodic gravitational waves from the neutron star in the supernova remnant Cassiopeia
A. The search coherently analyzes data in a 12 day interval taken from the fifth science run of the Laser
Interferometer Gravitational-Wave Observatory. It searches gravitational-wave frequencies from 100 to 300 Hz
and covers a wide range of first and second frequency derivatives appropriate for the age of the remnant and
for different spin-down mechanisms. No gravitational-wave signal was detected. Within the range of search
frequencies, we set 95% confidence upper limits of (0.7–1.2) × 10^(−24) on the intrinsic gravitational-wave
strain, (0.4–4) × 10^(−4) on the equatorial ellipticity of the neutron star, and 0.005–0.14 on the amplitude of
r-mode oscillations of the neutron star. These direct upper limits beat indirect limits derived from energy
conservation and enter the range of theoretical predictions involving crystalline exotic matter or runaway r-modes.
This paper is also the first gravitational-wave search to present upper limits on the r-mode amplitude
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