6,981 research outputs found
Nuclear star formation on 100 parsec scales: 10" resolution radio continuum, HI and CO observations
A program of radio line and continuum studies of star formation in nearby spiral galaxies is reported. The objective is a search for hot gas and peculiar dynamics in spiral nuclei with 10" to 30" angular resolution. Vigorous star formation is found to be a common phenomenon in the inner kpc of spirals. Arcsecond resolution observations of radio continuum emission at 6 and 2 cm were used to separate the thermal and nonthermal radio components. It was found that thermal and nonthermal emission are well mixed even on sizescales of 10 pc. To understand the reason for the increased level of star formation activity in spiral nuclei, HI and CO emission in these galaxies is studied. The CO transition was detected in M51, M82, NGC 253, NGC 6946 and IC 342 with T sub a approx. 0.5 to 2.0 K, at 20" angular resolution. The dynamics and spatial distribution of nuclear gas are being studied using VLA HI maps with 30" synthesized beams. Evidence for noncircular motions in HI was found in the nucleus of IC 342
Discovery of Radio Emission from the Tight M8 Binary: LP 349-25
We present radio observations of 8 ultracool dwarfs with a narrow spectral
type range (M8-M9.5) using the Very Large Array at 8.5 GHz. Only the tight M8
binary LP 349-25 was detected. LP 349-25 is the tenth ultracool dwarf system
detected in radio and its trigonometric parallax pi = 67.6 mas, recently
measured by Gatewood et al., makes it the furthest ultracool system detected by
the Very Large Array to date, and the most radio-luminous outside of obvious
flaring activity or variability. With a separation of only 1.8 AU, masses of
the components of LP 349-25 can be measured precisely without any theoretical
assumptions (Forveille et al.), allowing us to clarify their fully-convective
status and hence the kind of magnetic dynamo in these components which may play
an important role to explain our detection of radio emission from these
objects. This also makes LP 349-25 an excellent target for further studies with
better constraints on the correlations between X-ray, radio emission and
stellar parameters such as mass, age, temperature, and luminosity in ultracool
dwarfs.Comment: accepted by ApJ, referee's comments included, typo in equation 1
correcte
Pain and Suffering Damages in Wrongful Death Cases: An Empirical Study
Most jurisdictions in the United States award pain and suffering damages to spouses of victims in wrongful death cases. In several East Asian countries, spouses, parents, and children of the victim can all demand pain and suffering damages. Despite the prevalence of this type of damages, and the oftâenormous amount of compensation, there has been no largeâscale empirical study on how judges achieve the difficult task of assessing pain and suffering damages. Using a unique data set containing hundreds of car accident cases rendered by the court of first instance in Taiwan, with singleâequation and structuralâequation models, we find the plaintiffs\u27 ad damnum has a statistically significant influence on the courtâadjudicated pain and suffering damages. That could be evidence for the anchoring effect. Nevertheless, courts are very sensitive to the possibility of pushing defendants into financial hardship. When defendants\u27 outâofâpocket payments of pecuniary damages, divided by defendants\u27 income, are positive, this amount has a negative effect on the amount of pain and suffering damages, whereas when they are negative (this could happen because the amount of compulsory insurance payment had to be deducted), the amount in absolute value has a positive effect. Not all nextâofâkin received the same amount. Spouses of the victim received more than other nextâofâkin, and adult children received the least among eligible relatives. Parents, however, tended to be awarded a high amount of pain and suffering damages when they were the only familial group suing the defendant
Pain and Suffering Damages in Wrongful Death Cases: An Empirical Study
Most jurisdictions in the United States award pain and suffering damages to spouses of victims in wrongful death cases. In several East Asian countries, spouses, parents, and children of the victim can all demand pain and suffering damages. Despite the prevalence of this type of damages, and the oftâenormous amount of compensation, there has been no largeâscale empirical study on how judges achieve the difficult task of assessing pain and suffering damages. Using a unique data set containing hundreds of car accident cases rendered by the court of first instance in Taiwan, with singleâequation and structuralâequation models, we find the plaintiffs\u27 ad damnum has a statistically significant influence on the courtâadjudicated pain and suffering damages. That could be evidence for the anchoring effect. Nevertheless, courts are very sensitive to the possibility of pushing defendants into financial hardship. When defendants\u27 outâofâpocket payments of pecuniary damages, divided by defendants\u27 income, are positive, this amount has a negative effect on the amount of pain and suffering damages, whereas when they are negative (this could happen because the amount of compulsory insurance payment had to be deducted), the amount in absolute value has a positive effect. Not all nextâofâkin received the same amount. Spouses of the victim received more than other nextâofâkin, and adult children received the least among eligible relatives. Parents, however, tended to be awarded a high amount of pain and suffering damages when they were the only familial group suing the defendant
Oscillatory Tunneling between Quantum Hall Systems
Electron tunneling between quantum Hall systems on the same two dimensional
plane separated by a narrow barrier is studied. We show that in the limit where
inelastic scattering time is much longer than the tunneling time, which can be
achieved in practice, electrons can tunnel back and forth through the barrier
continously, leading to an oscillating current in the absence of external
drives. The oscillatory behavior is dictated by a tunneling gap in the energy
spectrum. We shall discuss ways to generate oscillating currents and the
phenomenon of natural ``dephasing" between the tunneling currents of edge
states. The noise spectra of these junctions are also studied. They contain
singularites reflecting the existence of tunneling gaps as well as the inherent
oscillation in the system. (Figures will be given upon requests).Comment: 20 pages, OS
A prospective randomized trial comparing sequential ganciclovir-high dose acyclovir to high dose acyclovir for prevention of cytomegalovirus disease in adult liver transplant recipients
Cytomegalovirus disease is an important cause of morbidity following liver transplantation. To date there has not been an effective prophylaxis for CMV disease after liver transplantation. One hundred forty-three patients were randomized to receive either high dose oral acyclovir (800 mg 4 times a day) alone for 3 months after transplantation (acyclovir group) or intravenous ganciclovir (5 mg/kg twice a day) for 14 days followed by high dose oral acyclovir to complete a 3-month regimen (ganciclovir group). Of 139 patients available for evaluation, 43 of 71 (61%) patients from the acyclovir group developed CMV infection compared with 16 of 68 (24%) from the ganciclovir group (relative risk, 3.69; 95% confidence interval, 2.07-6.56; PcO.OOOOl). Of those randomized, CMV disease was seen in 20 (28%) of the acyclovir group compared with 6 (9%) of the ganciclovir group (relative risk, 5.11; 95% confidence interval, 2.05-12.75; P=0.0001). The median time to onset of CMV infection was 45 days in the acyclovir group compared with 78 days in the ganciclovir group (P=0.004). The median time to onset of CMV disease was 40 days in the acyclovir group compared with 78 days in the ganciclovir patients (P=0.02). With respect to primary CMV infection, there was no difference in the rates in the 2 groups, but tissue invasive disease and recurrent CMV disease were less frequent in the ganciclovir group. It is concluded that a course of 2 weeks of ganciclovir immediately after transplantation followed by high dose oral acyclovir for 10 weeks is superior to a 12-week course of high dose oral acyclovir alone for prevention of both CMV infection and CMV disease after liver transplantation. However, the lack of significant effect in seronegative recipients who received grafts from seropositive donors suggests that other strategies are needed to prevent CMV infection in this high risk population. © 1994 by Williams & Wilkins
Simultaneous Absolute Timing of the Crab Pulsar at Radio and Optical Wavelengths
The Crab pulsar emits across a large part of the electromagnetic spectrum.
Determining the time delay between the emission at different wavelengths will
allow to better constrain the site and mechanism of the emission. We have
simultaneously observed the Crab Pulsar in the optical with S-Cam, an
instrument based on Superconducting Tunneling Junctions (STJs) with s time
resolution and at 2 GHz using the Nan\c{c}ay radio telescope with an instrument
doing coherent dedispersion and able to record giant pulses data. We have
studied the delay between the radio and optical pulse using simultaneously
obtained data therefore reducing possible uncertainties present in previous
observations. We determined the arrival times of the (mean) optical and radio
pulse and compared them using the tempo2 software package. We present the most
accurate value for the optical-radio lag of 255 21 s and suggest the
likelihood of a spectral dependence to the excess optical emission asociated
with giant radio pulses.Comment: 8 pages; accepted for publication in Astronomy and Astrophysic
- âŠ