712 research outputs found
Core-collapse astrophysics with a five-megaton neutrino detector
The legacy of solar neutrinos suggests that large neutrino detectors should be sited underground. However, to instead go underwater bypasses the need to move mountains, allowing much larger water Čerenkov detectors. We show that reaching a detector mass scale of ~5 Megatons, the size of the proposed Deep-TITAND, would permit observations of neutrino “mini-bursts” from supernovae in nearby galaxies on a roughly yearly basis, and we develop the immediate qualitative and quantitative consequences. Importantly, these mini-bursts would be detected over backgrounds without the need for optical evidence of the supernova, guaranteeing the beginning of time-domain MeV neutrino astronomy. The ability to identify, to the second, every core collapse in the local Universe would allow a continuous “death watch” of all stars within ~5 Mpc, making practical many previously-impossible tasks in probing rare outcomes and refining coordination of multiwavelength/multiparticle observations and analysis. These include the abilities to promptly detect otherwise-invisible prompt black hole formation, provide advance warning for supernova shock-breakout searches, define tight time windows for gravitational-wave searches, and identify “supernova impostors” by the nondetection of neutrinos. Observations of many supernovae, even with low numbers of detected neutrinos, will help answer questions about supernovae that cannot be resolved with a single high-statistics event in the Milky Way
Teachers' beliefs and practices about oral corrective feedback in university EFL classes
This study examined (in)congruences between beliefs and practices of EFL university teachers on in‐class oral corrective feedback (OCF). The participants were 20 university English language teachers from a private university in Turkey. Data were collected via video‐recorded non‐participant detached observation, a task about OCF to determine the beliefs of the teachers, and a stimulated recall interview. The results showed incongruence between what the teachers said they believed and what they did. However, teachers’ beliefs and practices were similar regarding whether the errors should be corrected, when errors should be corrected, and who should correct them. Particularly notable in this study was the finding that those teachers with the greatest incongruence almost always stood by their decisions, even after they watched their unsuccessful OCF practices
Strong Upper Limits on Sterile Neutrino Warm Dark Matter
Sterile neutrinos are attractive dark matter candidates. Their parameter
space of mass and mixing angle has not yet been fully tested despite intensive
efforts that exploit their gravitational clustering properties and radiative
decays. We use the limits on gamma-ray line emission from the Galactic Center
region obtained with the SPI spectrometer on the INTEGRAL satellite to set new
constraints, which improve on the earlier bounds on mixing by more than two
orders of magnitude, and thus strongly restrict a wide and interesting range of
models.Comment: 4 pages, 2 figures; minor revisions, accepted for publication in
Physical Review Letter
An Unexpectedly Swift Rise in the Gamma-ray Burst Rate
The association of long gamma-ray bursts with supernovae naturally suggests
that the cosmic GRB rate should trace the star formation history. Finding
otherwise would provide important clues concerning these rare, curious
phenomena. Using a new estimate of Swift GRB energetics to construct a sample
of 36 luminous GRBs with redshifts in the range z=0-4, we find evidence of
enhanced evolution in the GRB rate, with ~4 times as many GRBs observed at z~4
than expected from star formation measurements. This direct and empirical
demonstration of needed additional evolution is a new result. It is consistent
with theoretical expectations from metallicity effects, but other causes remain
possible, and we consider them systematically.Comment: 4 pages, 4 figures; minor changes to agree with published versio
Best-Bet Astrophysical Neutrino Sources
Likely astrophysical sources of detectable high-energy (>> TeV) neutrinos are
considered. Based on gamma-ray emission properties, the most probable sources
of neutrinos are argued to be GRBs, blazars, microquasars, and supernova
remnants. Diffuse neutrino sources are also briefly considered.Comment: 6 pages, 2 figures, in Proc. of TeV-Particle Astrophysics II,
Madison, WI, 28-31 Aug, 200
TeV Gamma Rays from Geminga and the Origin of the GeV Positron Excess
The Geminga pulsar has long been one of the most intriguing MeV-GeV gamma-ray
point sources. We examine the implications of the recent Milagro detection of
extended, multi-TeV gamma-ray emission from Geminga, finding that this reveals
the existence of an ancient, powerful cosmic-ray accelerator that can plausibly
account for the multi-GeV positron excess that has evaded explanation. We
explore a number of testable predictions for gamma-ray and electron/positron
experiments (up to ~100 TeV) that can confirm the first "direct" detection of a
cosmic-ray source.Comment: 4 pages and 3 figures; Minor revisions, accepted for publication in
Physical Review Letter
Antibiotic resistance and biofilm forming abilities of Listeria monocytogenes and effect of subMIC concentration of white vinegar on these virulence factors
In the present study, antibiotic resistance profiles and biofilm forming abilities of 9 Listeria monocytogenes isolates obtained from out of 30 retail meat samples were determined, and the effect of commercial white vinegar on these virulence factors in isolates exposed to subMIC concentrations were investigated. All isolates were found to be resistant to cefotixin and oxacillin, 8 isolates (26.6%) to clindamycin, 1 isolate (3.3%) to rifampicin, and 1 (3.3%) isolate was found to show intermediate resistance against clindamycin. Biofilm formation was determined for all the isolates at 22 °C and 37 °C (24 h, 48 h and 72 h). MIC values of white vinegar samples were determined at 3.12% for all isolates. MIC/2 and MIC/4 concentrations of white vinegar increased the biofilm forming capacity of the isolates by 21.2% and 17.1%, respectively. After exposure to MIC/2 concentration of white vinegar for seven days, the antibiotic resistance status of the isolates to tetracycline, rifampicin, and clindamycin changed, and the biofilm forming abilities significantly decreased at 4 °C and 37 °C for 48 h and at 37 °C for 72 h ( P < 0.05). The results showed that the use of subMIC concentrations of white vinegar should be avoided in routine sanitation applications
The Star Formation Rate in the Reionization Era as Indicated by Gamma-ray Bursts
High-redshift gamma-ray bursts (GRBs) offer an extraordinary opportunity to
study aspects of the early Universe, including the cosmic star formation rate
(SFR). Motivated by the two recent highest-z GRBs, GRB 080913 at z = 6.7 and
GRB 090423 at z = 8.1, and more than four years of Swift observations, we first
confirm that the GRB rate does not trace the SFR in an unbiased way. Correcting
for this, we find that the implied SFR to beyond z = 8 is consistent with
LBG-based measurements after accounting for unseen galaxies at the faint end of
the UV luminosity function. We show that this provides support for the
integrated star formation in the range 6 < z < 8 to have been alone sufficient
to reionize the Universe.Comment: 4 pages, 4 figures; modified to match version accepted for
publication in ApJ Letter
Effects of intrathecal bupivacaine and bupivacaine plus sufentanil in elderly patients undergoing transurethral resection
Introduction: The present study compared the effect of bupivacaine and bupivacaine + sufentanil on hemodynamic parameters and characteristics of spinal anesthesia in elderly patients undergoing transurethral resection of the prostate (TURP) under spinal anesthesia.Technical Considerations: The study included 40 American Society of Anesthesiologists (ASA) I‑III patients scheduled to undergo TURP. Patients were blindly and randomly divided into two groups. Group B (n = 20) received 10 mg of intrathecal bupivacaine and group BS (n = 20) received 7.5 mg of bupivacaine + 5 μg of sufentanil. Sensory and motor block characteristics, hemodynamic changes, side effects, and time to first analgesic requirement were recorded. No differences in mean arterial pressure or heart rate, time for sensory blockade to reach the T10 level, and maximum sensory level were observed between the two groups. The time to first analgesic request was longer in group BS (P < 0.05). Motor block was significantly higher in group B (P < 0.05). In terms of side effects, no statistically significant differences occurred between the groups.Conclusions: Similar hemodynamic stability and sufficient level of sensory blockade were provided by bupivacaine and bupivacaine + sufentanil used for spinal anesthesia in patients undergoing TUR. Due to the fact that less motor block was observed and the time to first analgesic request was longer, the combination of bupivacaine + sufentanil might be appropriate for patients undergoing TUR.Key words: Bupivacaine, intrathecal, opioid, spinal, sufentani
Neutrino physics from new SNO and KamLAND data and future prospects
We analyze the cumulative data from the latest SNO, KamLAND and other solar
neutrino experiments in the standard scenario of three oscillating active
neutrinos. We determine the solar neutrino oscillation parameters and obtain
new bounds on . We also place constraints on the fraction of
oscillating solar neutrinos that transform to sterile neutrinos with the B
flux normalization left free. Concomitantly, we assess the sensitivity of
future data from the SNO and KamLAND experiments to and to the
sterile neutrino content of the solar flux.Comment: 4 pages, 4 figures. Latest SNO salt-phase data and KamLAND data
included in analyse
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