Three-dimensional Quantum Slit Diffraction and Diffraction in Time

We study the quantum slit diffraction problem in three dimensions. In the treatment of diffraction of particles by a slit, it is usually assumed that the motion perpendicular to the slit is classical. Here we take into account the effect of the quantum nature of the motion perpendicular to the slit using the Green function approach [18]. We treat the diffraction of a Gaussian wave packet for general boundary conditions on the shutter. The difference between the standard and our three-dimensional slit diffraction models is analogous to the diffraction in time phenomenon introduced in [16]. We derive corrections to the standard formula for the diffraction pattern, and we point out situations in which this might be observable. In particular, we discuss the diffraction in space and time in the presence of gravity

Discrete-Time Path Distributions on Hilbert Space

We construct a path distribution representing the kinetic part of the Feynman path integral at discrete times similar to that defined by Thomas [1], but on a Hilbert space of paths rather than a nuclear sequence space. We also consider different boundary conditions and show that the discrete-time Feynman path integral is well-defined for suitably smooth potentials

Quantum slit diffraction in space and in time of a Gaussian wave packet and semi-classical approximation

We revisit the famous problem of quantum slit diffraction of a three-dimensional Gaussian wave packet, taking into account the diffraction in time phenomenon for a reflective or absorbing slit. We first recall the theory of diffraction in space and in time to give an explicit integral formula for the single-slit propagator (for a two-dimensional aperture) assuming that the time of opening the aperture coincides with the time of emission of the particle. Then we derive a semiclassical expression for the amplitude when the parameter μ = m(|r|^2)/(ħt) is large, where r is the position of the particle with mass m detected on the screen at the time t. We also give corrections to the law giving the distance between two fringes in the Fraunhofer regime when the distances of the apparatus in the propagation direction are large compared to the size of the aperture of the slit. To conclude, we discuss the phenomenological consequences and we give a new perspective to investigate the quantum diffraction phenomenon particulary for the cold atom slit experiment

Angular Power Spectrum Estimation of Cosmic Ray Anisotropies with Full or Partial Sky Coverage

We study the angular power spectrum estimate in order to search for large scale anisotropies in the arrival directions distribution of the highest-energy cosmic rays. We show that this estimate can be performed even in the case of partial sky coverage and validated over the full sky under the assumption that the observed fluctuations are statistically spatial stationary. If this hypothesis - which can be tested directly on the data - is not satisfied, it would prove, of course, that the cosmic ray sky is non isotropic but also that the power spectrum is not an appropriate tool to represent its anisotropies, whatever the sky coverage available. We apply the method to simulations of the Pierre Auger Observatory, reconstructing an input power spectrum with the Southern site only and with both Northern and Southern ones. Finally, we show the improvement that a full-sky observatory brings to test an isotropic distribution, and we discuss the sensitivity of the Pierre Auger Observatory to large scale anisotropies.Comment: 16 pages, 6 figures, version accepted for publication by JCA

Intermittent Pneumatic Compression Boot Use Elevates Blood Lactate During Subsequent Exercise

International Journal of Exercise Science 12(2): 385-392, 2019. The purpose of the present study was to investigate the influence of intermittent pneumatic compression (IPC) boot use between submaximal cycling trials on heart rate (HR) and blood lactate concentrations. Ten healthy participants (9M; 1F) performed two consecutive 60 minute rides at 60% of functional threshold power with a 30 minute rest between rides. The rest period was spent in a supine position using IPC boots (BOOT) or sitting in a similar position without boots (CON). HRs were collected every 15 minutes during cycling rides, and lactate was measured at the 30-minute mark during both rides. An identical trial was performed 7 days later with conditions (BOOT or CON) crossed. There were no between-trial differences (p \u3e 0.05) in HR; between-trial differences were found for lactate concentrations during the second ride (3.9 ± 1.0 mmol/L BOOT vs. 2.7 ± 1.5 mmol/L CON, p \u3c 0.05). The use of IPC boots between cycling trials as compared to laying in a supine position did not affect heart rate responses but did stimulate higher lactate concentrations during subsequent exercise

Acute Effects of Plyometric and Resistance Training on Running Economy in Trained Runners

Results regarding the acute effects of plyometric and resistance training (PRT) on running economy (RE) are conflicting. Eight male collegiate distance runners (21 +/- 1 years, 62.5 +/- 7.8 ml/kg/min V[Combining Dot Above]O2 peak) completed V[Combining Dot Above]O2 peak and 1 repetition maximum (1RM) testing. Seven days later, subjects completed a 12 minute RE test at 60% and 80% V[Combining Dot Above]O2 peak, followed by a PRT protocol or a rested condition of equal duration (CON). The PRT protocol consisted of 3 sets of 5 repetitions at 85% 1RM for barbell squats, Romanian deadlifts, and barbell lunges; the same volume was utilized for resisted lateral lunges, box jumps, and depth jumps. Subjects completed another RE test immediately following the treatments as well as 24 hours later. Subjects followed an identical protocol six days later with condition assignment reversed. RE was determined by both relative V[Combining Dot Above]O2 (ml/kg/min) as well as energy expenditure (kcal/min). There was a significant (p \u3c 0.05) between-trial increase in V[Combining Dot Above]O2 (37.1 +/- 4.2 ml/kg/min PRT vs. 35.5 +/- 3.9 ml/kg/min CON) and energy expenditure (11.4 +/- 1.3 kcal/min PRT vs. 11.0 +/- 1.4 kcal/min CON) immediately post-PRT at 60% V[Combining Dot Above]O2 peak, but no significant changes were observed at 80% V[Combining Dot Above]O2 peak. Respiratory exchange ratio (RER) was significantly (p \u3c 0.05) reduced 24 hours post-PRT (0.93 +/- 0.0) as compared to the CON trial (0.96 +/- 0.0) at 80% V[Combining Dot Above]O2 peak. Results indicate that high intensity PRT may acutely impair RE in aerobically trained individuals at a moderate running intensity, but that the attenuation lasts less than 24 hours in duration

Purkinje Cell Activity Determines the Timing of Sensory-Evoked Motor Initiation

Cerebellar neurons can signal sensory and motor events, but their role in active sensorimotor processing remains unclear. We record and manipulate Purkinje cell activity during a task that requires mice to rapidly discriminate between multisensory and unisensory stimuli before motor initiation. Neuropixels recordings show that both sensory stimuli and motor initiation are represented by short-latency simple spikes. Optogenetic manipulation of short-latency simple spikes abolishes or delays motor initiation in a rate-dependent manner, indicating a role in motor initiation and its timing. Two-photon calcium imaging reveals task-related coherence of complex spikes organized into conserved alternating parasagittal stripes. The coherence of sensory-evoked complex spikes increases with learning and correlates with enhanced temporal precision of motor initiation. These results suggest that both simple spikes and complex spikes govern sensory-driven motor initiation: simple spikes modulate its latency, and complex spikes refine its temporal precision, providing specific cellular substrates for cerebellar sensorimotor control

Physical Activity and Quality of Life in Retinitis Pigmentosa

Purpose. Aerobic exercise has been found to be neuroprotective in animal models of retinal degeneration. This study aims to report physical activity levels in patients with RP and investigate the relationship between physical activity and vision-related quality-of-life (QOL). Materials and Methods. A retrospective study of adult patients with RP examined in 2005–2014. Physical activity levels were assessed using the Godin Exercise Questionnaire. The NEI-Visual Function Questionaire-25 (VFQ-25), SF-36 General Health survey, and Pepper Assessment Tool for Disability (PAT-D) were administered. Results. 143 patients participated. 81 (56.6%) patients were classified as “active” and 62 (43.4%) as “insufficiently active” by Godin score. VFQ-25 revealed statistically significant differences between the active and insufficiently active patients, including overall visual function (53.3 versus 45.1, p=0.010), color vision (73.8 versus 52.9, p<0.001), and peripheral vision (34.3 versus 23.8, p=0.021). The physical component of the SF-36 and the PAT-D survey also demonstrated statistically significant differences (47.2 versus 52.9, p=0.002; 24.3 versus 30.0, p=0.010). Active patients had a higher initial Goldmann visual field (GVF) score (74.8 versus 60.1 degrees, p=0.255) and final GVF score (78.7 versus 47.1 degrees, p=0.069) but did not reach statistical significance. Conclusions. In RP, increased physical activity is associated with greater self-reported visual function and QOL

X-ray imaging with Micromegas detectors with optical readout

In the last years, optical readout of Micromegas gaseous detectors has been achieved by implementing a Micromegas detector on a glass anode coupled to a CMOS camera. Effective X-ray radiography was demonstrated using integrated imaging approach. High granularity values have been reached for low-energy X-rays from radioactive sources and X-ray generators. Detector characterization with X-ray radiography has led to two applications: neutron imaging for non-destructive examination of highly gamma-ray emitting objects and beta imaging for the single cell activity tagging in the field of oncology drug studies. First measurements investigating the achievable spatial resolution of the glass Micromegas detector at the SOLEIL synchrotron facility with a high-intensity and flat irradiation field will be shown in this article.Comment: 6 pages, 4 figures, 7th International Conference on Micro Pattern Gaseous Detectors, 11-16 December 20223, Weizmann Institute of Science, Rehovot, Israe