Risk and Benefit of the Concomitant Use of Benzodiazepines and Opiates

This presentation describes the possible benefits and risks associated with the concomitant use of opiate and benzodiazepine medications. Presented at the American Drug Utilization Review Society 2015 Conference

ASCA Observations of OAO 1657-415 and its Dust-Scattered X-Ray Halo

We report on two ASCA observations of the high-mass X-ray binary pulsar OAO 1657-415. A short observation near mid-eclipse caught the source in a low-intensity state, with a weak continuum and iron emission dominated by the 6.4-keV fluorescent line. A later, longer observation found the source in a high-intensity state and covered the uneclipsed through mid-eclipse phases. In the high-intensity state, the non-eclipse spectrum has an absorbed continuum component due to scattering by material near the pulsar and 80 per cent of the fluorescent iron emission comes from less than 19 lt-sec away from the pulsar. We find a dust-scattered X-ray halo whose intensity decays through the eclipse. We use this halo to estimate the distance to the source as 7.1 +/- 1.3 kpc.Comment: Accepted for publication in MNRA

The X-ray Globular Cluster Population in NGC 1399

We report on the {\it Chandra} observations of the elliptical galaxy NGC 1399, concentrating on the X-ray sources identified with globular clusters (GCs). A large fraction of the 2-10 keV X-ray emission in the $8' \times 8'$ {\it Chandra} image is resolved into point sources with luminosities $\ge 5 \times 10^{37}$ \ergsec. These sources are most likely Low Mass X-ray Binaries (LMXBs). In a region imaged by {\it HST} about 70% of the X-ray sources are located within GCs. This association suggests that in giant elliptical galaxies luminous X-ray binaries preferentially form in GCs. Many of the GC sources have super-Eddington luminosities (for an accreting neutron star) and their average luminosity is higher than the non-GC sources. The X-ray spectral properties of both GC and non-GC sources are similar to those of LMXBs in our Galaxy. Two of the brightest sources, one of which is in a GC, have an ultra-soft spectrum, similar to that seen in the high state of black hole candidates. The ``apparent'' super-Eddington luminosity in many cases may be due to multiple LMXB systems within individual GCs, but with some of the most extremely luminous systems containing massive black holes.Comment: accepted in ApJ letter. 10 pages 5 figure

A phase separation in diluted Laponite suspensions: evidence of empty liquid and equilibrium gel states

The relevance of anisotropic interactions in colloidal systems has recently emerged in the context of rational design of novel soft materials. Theoretical studies have predicted the possibility of a gas-liquid phase separation confined at low densities and the formation of empty liquids and equilibrium gels in low-valence systems. Here we provide experimental evidence of this scenario in Laponite, a complex colloidal clay with discotic shape and anisotropic interactions. We also report simulations of a patchy model for Laponite platelets, able to reproduce the observed experimental phase diagram and structural properties, confirming the crucial role of the reduced valence

A Universal Slope Set for 1-Bend Planar Drawings

We describe a set of Delta-1 slopes that are universal for 1-bend planar drawings of planar graphs of maximum degree Delta>=4; this establishes a new upper bound of Delta-1 on the 1-bend planar slope number. By universal we mean that every planar graph of degree Delta has a planar drawing with at most one bend per edge and such that the slopes of the segments forming the edges belong to the given set of slopes. This improves over previous results in two ways: Firstly, the best previously known upper bound for the 1-bend planar slope number was 3/2(Delta-1) (the known lower bound being 3/4(Delta-1)); secondly, all the known algorithms to construct 1-bend planar drawings with O(Delta) slopes use a different set of slopes for each graph and can have bad angular resolution, while our algorithm uses a universal set of slopes, which also guarantees that the minimum angle between any two edges incident to a vertex is pi/(Delta-1)

Obstacle crossing behaviors in firefighters: effects of personal protective equipment and firefighter activity

Firefighting is an inherently dangerous occupation in which intrinsic hazards such as fatigue from physical exertion as well as extrinsic obstacles are commonly encountered. These hazards can lead to slip, trip, and fall (STF) related injuries, which constitute a large portion of annual severe firefighting injuries. The key objective of this work was to assess firefighters’ risk of STF injuries by observing performance when crossing a stationary obstacle. Two studies were carried out to accomplish this goal. The first of these studies examined the effects of fatigue induced by several different simulated firefighting exercise protocols, as well as the carriage of a unilateral hose load when traversing the obstacle. Three simulated firefighting protocols were implemented, with each intended to replicate the environmental conditions and required workload of actual firefighting. To examine changes in movement behavior as a result of the fatigue induced by each condition, firefighters completed a functional task course which included traversing a stationary obstacle both before and immediately after each protocol. In half of the trials, subjects carried a hose pack unilaterally. Obstacle contact errors and both horizontal and vertical clearances of each foot over the obstacle were measured. Significant changes were observed as a result of fatigue, unilateral load carriage, and protocol. The results of this study can help to develop a standard for simulated firefighting, and may ultimately help lead to a reduction in slip, trip, and fall injuries by providing a better understanding of how fatigue and load carriage can impact movement behavior on the fireground. The second study examined the effects of different sizes and designs of SCBA as well as the fatigue effects of extended duration firefighting on obstacle crossing ability. Larger capacity SCBA cylinders are becoming more widely available, allowing for longer periods of continuous firefighting. Furthermore, novel SCBA pack designs beyond traditional cylinder geometries are being developed to improve biomechanical compatibility. To assess biomechanical changes induced by these factors, firefighters again completed the functional task course including crossing a stationary obstacle both before and immediately after undergoing one of three simulated firefighting protocols and using varying types of SCBA. Obstacle contact errors, obstacle clearances, and peak normalized ground reaction forces (GRFs) were measured. For this study, several clearance metrics which had not been widely utilized previously were implemented and compared to the more common horizontal and vertical clearance metric. Few effects of SCBA size or design were observed, while effects of fatigue and exercise protocol were more apparent. The new clearance metrics were also observed to be more sensitive in detecting statistically significant changes than the more common clearance metrics. The results suggested that the effects of SCBA size and design on obstacle crossing ability are minimal, while fatigue – particularly that induced by extended duration firefighting, regardless of rehabilitation – increases the risk of STF injury. These results also suggest that the use of the new clearance metrics can provide useful information on changes in obstacle crossing behavior which may not be apparent from the commonly utilized metrics. These results may provide a better understanding of how equipment and varying degrees of fatigue contribute to the risk of STFs and their associated injuries, and may assist fire departments in making informed decisions when outfitting their firefighters

Axis-Parallel Right Angle Crossing Graphs

A RAC graph is one admitting a RAC drawing, that is, a polyline drawing in which each crossing occurs at a right angle. Originally motivated by psychological studies on readability of graph layouts, RAC graphs form one of the most prominent graph classes in beyond planarity. In this work, we study a subclass of RAC graphs, called axis-parallel RAC (or apRAC, for short), that restricts the crossings to pairs of axis-parallel edge-segments. apRAC drawings combine the readability of planar drawings with the clarity of (non-planar) orthogonal drawings. We consider these graphs both with and without bends. Our contribution is as follows: (i) We study inclusion relationships between apRAC and traditional RAC graphs. (ii) We establish bounds on the edge density of apRAC graphs. (iii) We show that every graph with maximum degree 8 is 2-bend apRAC and give a linear time drawing algorithm. Some of our results on apRAC graphs also improve the state of the art for general RAC graphs. We conclude our work with a list of open questions and a discussion of a natural generalization of the apRAC model

Axis-Parallel Right Angle Crossing Graphs

A RAC graph is one admitting a RAC drawing, that is, a polyline drawing in which each crossing occurs at a right angle. Originally motivated by psychological studies on readability of graph layouts, RAC graphs form one of the most prominent graph classes in beyond planarity. In this work, we study a subclass of RAC graphs, called axis-parallel RAC (or apRAC, for short), that restricts the crossings to pairs of axis-parallel edge-segments. apRAC drawings combine the readability of planar drawings with the clarity of (non-planar) orthogonal drawings. We consider these graphs both with and without bends. Our contribution is as follows: (i) We study inclusion relationships between apRAC and traditional RAC graphs. (ii) We establish bounds on the edge density of apRAC graphs. (iii) We show that every graph with maximum degree 8 is 2-bend apRAC and give a linear time drawing algorithm. Some of our results on apRAC graphs also improve the state of the art for general RAC graphs. We conclude our work with a list of open questions and a discussion of a natural generalization of the apRAC model