Analysis of sonic boom measurements near shock wave extremities for flight near Mach 1.0 and for airplane accelerations

The analysis of the 14 low-altitude transonic flights showed that the prevailing meteorological consideration of the acoustic disturbances below the cutoff altitude during threshold Mach number flight has shown that a theoretical safe altitude appears to be valid over a wide range of meteorological conditions and provides a reasonable estimate of the airplane ground speed reduction to avoid sonic boom noise during threshold Mach number flight. Recent theoretical results for the acoustic pressure waves below the threshold Mach number caustic showed excellent agreement with observations near the caustic, but the predicted overpressure levels were significantly lower than those observed far from the caustic. The analysis of caustics produced by inadvertent low-magnitude accelerations during flight at Mach numbers slightly greater than the threshold Mach number showed that folds and associated caustics were produced by slight changes in the airplane ground speed. These caustic intensities ranged from 1 to 3 time the nominal steady, level flight intensity

Peer Effects in Team Sports: Empirical Evidence from NCAA Relay Teams

This paper investigates whether disparity in team member quality impacts team production using NCAA 4x400m relay teams. The net peer effects are estimated to have both an absolute and relative negative effect on the team performance. Because NCAA relay teams are comprised of unpaid amateurs, we utilize a direct measure of team-member quality rather than indirect measures such as wages. The evidence suggests that a greater disparity in team member quality reduces team performance, that is, it increases a relay team’s running time. This suggests that net negative peer effects exist and support the “team cohesiveness hypothesis” for NCAA relay teams.teamwork, shirking, track and field, sports

A minimaj-preserving crystal on ordered multiset partitions

We provide a crystal structure on the set of ordered multiset partitions, which recently arose in the pursuit of the Delta Conjecture. This conjecture was stated by Haglund, Remmel and Wilson as a generalization of the Shuffle Conjecture. Various statistics on ordered multiset partitions arise in the combinatorial analysis of the Delta Conjecture, one of them being the minimaj statistic, which is a variant of the major index statistic on words. Our crystal has the property that the minimaj statistic is constant on connected components of the crystal. In particular, this yields another proof of the Schur positivity of the graded Frobenius series of the generalization $R_{n,k}$ due to Haglund, Rhoades and Shimozono of the coinvariant algebra $R_n$. The crystal structure also enables us to demonstrate the equidistributivity of the minimaj statistic with the major index statistic on ordered multiset partitions.Comment: 17 pages; v2 contains minor changes suggested by referee, references update

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Integration of GaAs-based VCSEL array on SiN platform with HCG reflectors for WDM applications

We present a GaAs-based VCSEL structure, BCB bonded to a Si3N4 waveguide circuit, where one DBR is substituted by a free-standing Si3N4 high-contrast-grating (HCG) reflector realized in the Si3N4 waveguide layer. This design enables solutions for on-chip spectroscopic sensing, and the dense integration of 850-nm WDM data communication transmitters where individual channel wavelengths are set by varying the HCG parameters. RCWA shows that a 300nm-thick Si3N4 HCG with 800nm period and 40% duty cycle reflects strongly (>99%) over a 75nm wavelength range around 850nm. A design with a standing-optical-field minimum at the III-V/airgap interface maximizes the HCG's influence on the VCSEL wavelength, allowing for a 15-nm-wide wavelength setting range with low threshold gain (<1000 cm(-1))

Instantaneous band gap collapse in photoexcited monoclinic VO2_2 due to photocarrier doping

Using femtosecond time-resolved photoelectron spectroscopy we demonstrate that photoexcitation transforms monoclinic VO$_2$ quasi-instantaneously into a metal. Thereby, we exclude an 80 femtosecond structural bottleneck for the photoinduced electronic phase transition of VO$_2$. First-principles many-body perturbation theory calculations reveal a high sensitivity of the VO$_2$ bandgap to variations of the dynamically screened Coulomb interaction, supporting a fully electronically driven isostructral insulator-to-metal transition. We thus conclude that the ultrafast band structure renormalization is caused by photoexcitation of carriers from localized V 3d valence states, strongly changing the screening \emph{before} significant hot-carrier relaxation or ionic motion has occurred

A Theater Intervention to Prevent Teen Dating Violence for Mexican-American Middle School Students

Purpose To test a theater intervention designed to raise awareness of the dynamics and consequences of teen dating violence (TDV) and to facilitate creation of nonviolent responses to TDV among Latino and Latina adolescents. The intervention was based on Theater of the Oppressed, which advocates the use of theater methods to explore social issues and to allow audiences to experiment with problem-solving, thereby promoting change. Methods This study used a pretest–posttest, no control group, mixed-measures design to study 66 Mexican-American adolescents (mean age, 13.4 ± 5 years). Two plays containing subtle and overt signs of control and abuse were written and performed. Scripts were based on data from prior studies of TDV among Latino and Latina adolescents. At baseline, we measured sociodemographics, personal safety, and ethnic identity. Pre–post instruments measured acceptance of TDV, confidence to resolve conflicts nonviolently, and intentions to use nonviolent strategies to resolve conflict. We collected qualitative data via essay. Results At posttest, participants had less acceptance of TDV (t = −2.08; p \u3c .05), increased confidence to resolve conflicts nonviolently (t = 3.82; p \u3c .001), and higher intentions to use nonviolent strategies (t = 3.35; p = .001). We analyzed 20 essays. Qualitative results provided context for understanding participants\u27 changes in attitude, confidence, and nonviolent behavioral intentions. Conclusions This adaptation of Theater of the Oppressed was an effective way to interact with Latino adolescents. In a safe setting, participants vicariously experienced TDV, which facilitated self-reflection and cognitive rehearsal strategies to respond nonviolently to TDV