Magnetocentrifugally Driven Flows from Young Stars and Disks. VI. Accretion with a Multipole Stellar Field

Previous analyses of magnetospheric accretion and outflow in classical T Tauri stars (CTTSs), within the context of both the X-wind model and other theoretical scenarios, have assumed a dipolar geometry for the stellar magnetic field if it were not perturbed by the presence of an accreting, electrically conducting disk. However, CTTS surveys reveal that accretion hot spots cover a small fraction of the stellar surface, and that the net field polarization on the stellar surface is small. Both facts imply that the magnetic field generated by the star has a complex non-dipolar structure. To address this discrepancy between theory and observations, we re-examine X-wind theory without the dipole constraint. Using simple physical arguments based on the concept of trapped flux, we show that a dipole configuration is in fact not essential. Independent of the precise geometry of the stellar magnetosphere, the requirement for a certain level of trapped flux predicts a definite relationship among various CTTS observables. Moreover, superposition of multipole stellar fields naturally yield small observed hot-spot covering fractions and small net surface polarizations. The generalized X-wind picture remains viable under these conditions, with the outflow from a small annulus near the inner disk edge little affected by the modified geometry, but with inflow highly dependent on the details of how the emergent stellar flux is linked and trapped by the inner disk regions. Our model is consistent with data, including recent spectropolarimetric measurements of the hot spot sizes and field strengths in V2129 Oph and BP Tau.Comment: ApJ accepted; 47 pages (submission format), 7 figure

Event-based simulation of interference with alternatingly blocked particle sources

We analyze the predictions of an event-based corpuscular model for interference in the case of two-beam interference experiments in which the two sources are alternatingly blocked. We show that such experiments may be used to test specific predictions of the corpuscular model.Comment: FPP6 - Foundations of Probability and Physics 6, edited by A. Khrennikov et al., AIP Conference Proceeding

Comment on "Cherenkov Radiation by Neutrinos in a Supernova Core"

Mohanty and Samal have shown that the magnetic-moment interaction with nucleons contributes significantly to the photon dispersion relation in a supernova core, and with an opposite sign relative to the usual plasma effect. Because of a numerical error they overestimated the magnetic-moment term by two orders of magnitude, but it is still of the same order as the plasma effect. It appears that the Cherenkov processes gamma+nu -> nu and nu -> nu+gamma remain forbidden, but a final verdict depends on a more detailed investigation of the dynamical magnetic susceptibility of a hot nuclear medium.Comment: 2 pages, REVTEX. Submitted as a Comment to PR

Micromechanical microphone using sideband modulation of nonlinear resonators

We report the successful detection of an audio signal via sideband modulation of a nonlinear piezoelectric micromechanical resonator. The 270$\times$96-$\mu$m resonator was shown to be reliable in audio detection for sound intensity levels as low as ambient room noise and to have an unamplified sensitivity of 23.9 $\mu$V/Pa. Such an approach may be adapted in acoustic sensors and microphones for consumer electronics or medical equipment such as hearing aids.Comment: 5 pages, 3 figure

Diagnostic efficacy of Striae Gravidarum in predicting intraperitoneal adhesions and uterine scar thickness in women undergoing repeat caesarean section

Background: Striae gravidarum (SG) are stretch marks on the skin which develop during pregnancy. Cesarean section is one of the most common operation performed worldwide which carries a potential risk of complications due to the intra-peritoneal adhesions and thickness of previous uterine scar. The aim of this study was to find the diagnostic efficacy of striae gravidarum in predicting intra-peritoneal adhesions (IPA) and uterine scar thickness in women undergoing repeated caesarean delivery.Methods: It was a cross-sectional study done over a period of 18 months duration. One hundred women with previous cesarean section scheduled for elective LSCS were enrolled for the study. Striae gravidarum was calculated according to the Atwal numerical scoring system. Presence of intra-peritoneal adhesions were graded intraoperatively according to modified Nair scoring system. After extraction of baby, the thickness of lower uterine segment at midpoint of lower flap of uterine incision was measured by metallic screw gauge.Results: Significant positive correlation was seen between striae gravidarum and intra-peritoneal adhesions. A negative association was established between striae gravidarum severity and thickness of LUS. Owing to its moderately high sensitivity and low specificity in predicting IPA Grade 3 or 4 and LUS scar thickness<3.74mm, striae gravidarum cannot be used as a diagnostic indicator, but can be a useful mass screening method.Conclusions: Striae gravidarum is a zero-cost simple quick and easy technique which can be universally used with minimal intra-observer variation to predict perioperative complications in low resource settings