116 research outputs found
ABJ(M) and Fractional M2's with Fractional M2 Charge
Recently Aharony, Bergman and Jafferis (ABJ) have argued that a 3d
U(N+M)xU(N) Chern-Simons gauge theory at level (k,-k) may have a vacuum with
N=6 supersymmetry only if M<k+1 and if a certain period of the B-field in a IIA
background is quantized. We use a braneology argument to argue that N=3
supersymmetry may be preserved under the weaker condition that 2Nk>M(M-k)-1
with no restriction on the B-field. IIB brane cartoons and 11d supergravity
solutions corresponding to N=3 vacua that do not preserve N=6 supersymmetry are
argued to represent cascading gauge theories, generalizing the N=2 Seiberg
duality conjectured by Giveon and Kutasov. While as usual the M2-brane charge
runs as a result of the twisted Bianchi identity for *G_4, the M5-brane charge
running relies on the fact that it wraps a torsion homology cycle.Comment: 16 pages, 3 eps figure
Current-induced cooling phenomenon in a two-dimensional electron gas under a magnetic field
We investigate the spatial distribution of temperature induced by a dc
current in a two-dimensional electron gas (2DEG) subjected to a perpendicular
magnetic field. We numerically calculate the distributions of the electrostatic
potential phi and the temperature T in a 2DEG enclosed in a square area
surrounded by insulated-adiabatic (top and bottom) and isopotential-isothermal
(left and right) boundaries (with phi_{left} < phi_{right} and T_{left}
=T_{right}), using a pair of nonlinear Poisson equations (for phi and T) that
fully take into account thermoelectric and thermomagnetic phenomena, including
the Hall, Nernst, Ettingshausen, and Righi-Leduc effects. We find that, in the
vicinity of the left-bottom corner, the temperature becomes lower than the
fixed boundary temperature, contrary to the naive expectation that the
temperature is raised by the prevalent Joule heating effect. The cooling is
attributed to the Ettingshausen effect at the bottom adiabatic boundary, which
pumps up the heat away from the bottom boundary. In order to keep the adiabatic
condition, downward temperature gradient, hence the cooled area, is developed
near the boundary, with the resulting thermal diffusion compensating the upward
heat current due to the Ettingshausen effect.Comment: 25 pages, 7 figure
Central-line-associated bloodstream infection burden among Dutch neonatal intensive care units
Background: The establishment of an epidemiological overview provides valuable insights needed for the (future) dissemination of infection-prevention initiatives. Aim: To describe the nationwide epidemiology of central-line-associated bloodstream infections (CLABSI) among Dutch Neonatal Intensive Care Units (NICUs). Methods: Data from 2935 neonates born at <32 weeks' gestation and/or with a birth weight <1500 g admitted to all nine Dutch NICUs over a two-year surveillance period (2019–2020) were analysed. Variations in baseline characteristics, CLABSI incidence per 1000 central-line days, pathogen distribution and CLABSI care bundles were evaluated. Multi-variable logistic mixed-modelling was used to identify significant predictors for CLABSI. Results:A total of 1699 (58%) neonates received a central line, in which 160 CLABSI episodes were recorded. Coagulase-negative staphylococci were the most common infecting organisms of all CLABSI episodes (N=100, 63%). An almost six-fold difference in the CLABSI incidence between participating units was found (2.91–16.14 per 1000 line-days). Logistic mixed-modelling revealed longer central line dwell-time (adjusted odds ratio (aOR):1.08, P<0.001), umbilical lines (aOR:1.85, P=0.03) and single rooms (aOR:3.63, P=0.02) to be significant predictors of CLABSI. Variations in bundle elements included intravenous tubing care and antibiotic prophylaxis. Conclusions: CLABSI remains a common problem in preterm infants in The Netherlands, with substantial variation in incidence between centres. Being the largest collection of data on the burden of neonatal CLABSI in The Netherlands, this epidemiological overview provides a solid foundation for the development of a collaborative platform for continuous surveillance, ideally leading to refinement of national evidence-based guidelines. Future efforts should focus on ensuring availability and extraction of routine patient data in aggregated formats.</p
Central-line-associated bloodstream infection burden among Dutch neonatal intensive care units
Background: The establishment of an epidemiological overview provides valuable insights needed for the (future) dissemination of infection-prevention initiatives. Aim: To describe the nationwide epidemiology of central-line-associated bloodstream infections (CLABSI) among Dutch Neonatal Intensive Care Units (NICUs). Methods: Data from 2935 neonates born at <32 weeks' gestation and/or with a birth weight <1500 g admitted to all nine Dutch NICUs over a two-year surveillance period (2019–2020) were analysed. Variations in baseline characteristics, CLABSI incidence per 1000 central-line days, pathogen distribution and CLABSI care bundles were evaluated. Multi-variable logistic mixed-modelling was used to identify significant predictors for CLABSI. Results:A total of 1699 (58%) neonates received a central line, in which 160 CLABSI episodes were recorded. Coagulase-negative staphylococci were the most common infecting organisms of all CLABSI episodes (N=100, 63%). An almost six-fold difference in the CLABSI incidence between participating units was found (2.91–16.14 per 1000 line-days). Logistic mixed-modelling revealed longer central line dwell-time (adjusted odds ratio (aOR):1.08, P<0.001), umbilical lines (aOR:1.85, P=0.03) and single rooms (aOR:3.63, P=0.02) to be significant predictors of CLABSI. Variations in bundle elements included intravenous tubing care and antibiotic prophylaxis. Conclusions: CLABSI remains a common problem in preterm infants in The Netherlands, with substantial variation in incidence between centres. Being the largest collection of data on the burden of neonatal CLABSI in The Netherlands, this epidemiological overview provides a solid foundation for the development of a collaborative platform for continuous surveillance, ideally leading to refinement of national evidence-based guidelines. Future efforts should focus on ensuring availability and extraction of routine patient data in aggregated formats.</p
Central-line-associated bloodstream infection burden among Dutch neonatal intensive care units
Background: The establishment of an epidemiological overview provides valuable insights needed for the (future) dissemination of infection-prevention initiatives. Aim: To describe the nationwide epidemiology of central-line-associated bloodstream infections (CLABSI) among Dutch Neonatal Intensive Care Units (NICUs). Methods: Data from 2935 neonates born at <32 weeks' gestation and/or with a birth weight <1500 g admitted to all nine Dutch NICUs over a two-year surveillance period (2019–2020) were analysed. Variations in baseline characteristics, CLABSI incidence per 1000 central-line days, pathogen distribution and CLABSI care bundles were evaluated. Multi-variable logistic mixed-modelling was used to identify significant predictors for CLABSI. Results: A total of 1699 (58%) neonates received a central line, in which 160 CLABSI episodes were recorded. Coagulase-negative staphylococci were the most common infecting organisms of all CLABSI episodes (N=100, 63%). An almost six-fold difference in the CLABSI incidence between participating units was found (2.91–16.14 per 1000 line-days). Logistic mixed-modelling revealed longer central line dwell-time (adjusted odds ratio (aOR):1.08, P<0.001), umbilical lines (aOR:1.85, P=0.03) and single rooms (aOR:3.63, P=0.02) to be significant predictors of CLABSI. Variations in bundle elements included intravenous tubing care and antibiotic prophylaxis. Conclusions: CLABSI remains a common problem in preterm infants in The Netherlands, with substantial variation in incidence between centres. Being the largest collection of data on the burden of neonatal CLABSI in The Netherlands, this epidemiological overview provides a solid foundation for the development of a collaborative platform for continuous surveillance, ideally leading to refinement of national evidence-based guidelines. Future efforts should focus on ensuring availability and extraction of routine patient data in aggregated formats
Calabi-Yau Volumes and Reflexive Polytopes
We study various geometrical quantities for Calabi–Yau varieties realized as cones over Gorenstein Fano varieties, obtained as toric varieties from reflexive polytopes in various dimensions. Focus is made on reflexive polytopes up to dimension 4 and the minimized volumes of the Sasaki–Einstein base of the corresponding Calabi–Yau cone are calculated. By doing so, we conjecture new bounds for the Sasaki–Einstein volume with respect to various topological quantities of the corresponding toric varieties. We give interpretations about these volume bounds in the context of associated field theories via the AdS/CFT correspondence
The evolution of language: a comparative review
For many years the evolution of language has been seen as a disreputable topic, mired in fanciful "just so stories" about language origins. However, in the last decade a new synthesis of modern linguistics, cognitive neuroscience and neo-Darwinian evolutionary theory has begun to make important contributions to our understanding of the biology and evolution of language. I review some of this recent progress, focusing on the value of the comparative method, which uses data from animal species to draw inferences about language evolution. Discussing speech first, I show how data concerning a wide variety of species, from monkeys to birds, can increase our understanding of the anatomical and neural mechanisms underlying human spoken language, and how bird and whale song provide insights into the ultimate evolutionary function of language. I discuss the ‘‘descended larynx’ ’ of humans, a peculiar adaptation for speech that has received much attention in the past, which despite earlier claims is not uniquely human. Then I will turn to the neural mechanisms underlying spoken language, pointing out the difficulties animals apparently experience in perceiving hierarchical structure in sounds, and stressing the importance of vocal imitation in the evolution of a spoken language. Turning to ultimate function, I suggest that communication among kin (especially between parents and offspring) played a crucial but neglected role in driving language evolution. Finally, I briefly discuss phylogeny, discussing hypotheses that offer plausible routes to human language from a non-linguistic chimp-like ancestor. I conclude that comparative data from living animals will be key to developing a richer, more interdisciplinary understanding of our most distinctively human trait: language
All-sky search for long-duration gravitational wave transients with initial LIGO
We present the results of a search for long-duration gravitational wave transients in two sets of data collected by the LIGO Hanford and LIGO Livingston detectors between November 5, 2005 and September 30, 2007, and July 7, 2009 and October 20, 2010, with a total observational time of 283.0 days and 132.9 days, respectively. The search targets gravitational wave transients of duration 10-500 s in a frequency band of 40-1000 Hz, with minimal assumptions about the signal waveform, polarization, source direction, or time of occurrence. All candidate triggers were consistent with the expected background; as a result we set 90% confidence upper limits on the rate of long-duration gravitational wave transients for different types of gravitational wave signals. For signals from black hole accretion disk instabilities, we set upper limits on the source rate density between 3.4×10-5 and 9.4×10-4 Mpc-3 yr-1 at 90% confidence. These are the first results from an all-sky search for unmodeled long-duration transient gravitational waves. © 2016 American Physical Society
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