5,142 research outputs found

    Utilizing AI in Temporal, Spatial, and Resource Scheduling

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    Aurora is a software system enabling the rapid, easy solution of complex scheduling problems involving spatial and temporal constraints among operations and scarce resources (such as equipment, workspace, and human experts). Although developed for use in the International Space Station Processing Facility, Aurora is flexible enough that it can be easily customized for application to other scheduling domains and adapted as the requirements change or become more precisely known over time. Aurora s scheduling module utilizes artificial-intelligence (AI) techniques to make scheduling decisions on the basis of domain knowledge, including knowledge of constraints and their relative importance, interdependencies among operations, and possibly frequent changes in governing schedule requirements. Unlike many other scheduling software systems, Aurora focuses on resource requirements and temporal scheduling in combination. For example, Aurora can accommodate a domain requirement to schedule two subsequent operations to locations adjacent to a shared resource. The graphical interface allows the user to quickly visualize the schedule and perform changes reflecting additional knowledge or alterations in the situation. For example, the user might drag the activity corresponding to the start of operations to reflect a late delivery

    A Potential Role for the Interaction of Wolbachia Surface Proteins with the Brugia malayi Glycolytic Enzymes and Cytoskeleton in Maintenance of Endosymbiosis

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    The human filarial parasite Brugia malayi harbors an endosymbiotic bacterium of the genus Wolbachia. The Wolbachia represent an attractive target for the control of filarial induced disease as elimination of the bacteria affects molting, reproduction and survival of the worms. The molecular basis for the symbiotic relationship between Wolbachia and their filarial hosts has yet to be elucidated. To identify proteins involved in this process, we focused on the Wolbachia surface proteins (WSPs), which are known to be involved in bacteria-host interactions in other bacterial systems. Two WSP-like proteins (wBm0152 and wBm0432) were localized to various host tissues of the B. malayi female adult worms and are present in the excretory/secretory products of the worms. We provide evidence that both of these proteins bind specifically to B. malayi crude protein extracts and to individual filarial proteins to create functional complexes. The wBm0432 interacts with several key enzymes involved in the host glycolytic pathway, including aldolase and enolase. The wBm0152 interacts with the host cytoskeletal proteins actin and tubulin. We also show these interactions in vitro and have verified that wBm0432 and B. malayi aldolase, as well as wBm0152 and B. malayi actin, co-localize to the vacuole surrounding Wolbachia. We propose that both WSP protein complexes interact with each other via the aldolase-actin link and/or via the possible interaction between the host's enolase and the cytoskeleton, and play a role in Wolbachia distribution during worm growth and embryogenesis. © 2013 Melnikow et al

    Massive Dirac fermions in a ferromagnetic kagome metal

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    The kagome lattice is a two-dimensional network of corner-sharing triangles known as a platform for exotic quantum magnetic states. Theoretical work has predicted that the kagome lattice may also host Dirac electronic states that could lead to topological and Chern insulating phases, but these have evaded experimental detection to date. Here we study the d-electron kagome metal Fe3_3Sn2_2 designed to support bulk massive Dirac fermions in the presence of ferromagnetic order. We observe a temperature independent intrinsic anomalous Hall conductivity persisting above room temperature suggestive of prominent Berry curvature from the time-reversal breaking electronic bands of the kagome plane. Using angle-resolved photoemission, we discover a pair of quasi-2D Dirac cones near the Fermi level with a 30 meV mass gap that accounts for the Berry curvature-induced Hall conductivity. We show this behavior is a consequence of the underlying symmetry properties of the bilayer kagome lattice in the ferromagnetic state with atomic spin-orbit coupling. This report provides the first evidence for a ferromagnetic kagome metal and an example of emergent topological electronic properties in a correlated electron system. This offers insight into recent discoveries of exotic electronic behavior in kagome lattice antiferromagnets and may provide a stepping stone toward lattice model realizations of fractional topological quantum states.Comment: 19 pages, 4 figure

    Dobutamine stress MR in Tetralogy of Fallot with significant pulmonary regurgitation, safety, feasibility and haemodynamic effects

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    Introduction In Tetralogy of Fallot (TOF) late after repair, severe pulmonary regurgitation (PR) places the patient at risk for right ventricular (RV) dilatation and failure, arrhythmia and sudden cardiac death. Criteria for pulmonary valve replacement continue to be debated. Dobutamine stress MR (DS-MR) may improve diagnostic sensitivity to detect early RV dysfunction. We sought to investigate safety, feasibility and haemodynamic effect of DS-MR. Methods We prospectively recruited 28 adult patients referred for cardiac MR (age 32±15) with repaired TOF, RV dilatation and severe PR on echocardiography. Exclusion criteria: Contraindications to MR, history of arrhythmia, severely impaired left ventricular (LV) function, severe aortic valve disease, and severe pulmonary stenosis. Ventricular volumes (axial 2D cine SSFP) and pulmonary artery and aortic flows (phase contrast) were obtained at baseline and during dobutamine infusion of 10 mcg/kg/min (stage 1) and 20 mcg/kg/min (stage 2). DS-MR was stopped when systolic blood pressure >190 mmHg, heart rate >75% predicted (220-age) or if patients experienced significant side effects. Results Of the 28 patients, 24 completed stage 1 DS-MR (two subject experienced claustrophobia and two had failure of VECG triggering secondary to frequent ventricular ectopics not present during baseline scanning. Four of these 24 patients could not progress to Stage 2, due to either minor dobutamine side effects (nausea or headache, n=2) or achievement of >75% maximum predicted heart rate (n=2). Twenty patients went on to complete stage 2 DS-MR and no additional side effects were observed. Two data sets at stage 2 were excluded from analysis due to incomplete volumetric measurements. The heart rate (cardiac index) increased from 66±6 bpm (2.9±0.4 l/min/m2) at baseline to 91±18 bpm (3.9±0.9 l/min/m2) at Stage 1 and 117±14 bpm (4.5±1 l/min/m2) at Stage 2 (p<0.01). Significant reduction in LV end diastolic (EDV) and end systolic volumes (ESV) is seen at dobutamine 10 and 20 (p<0.01). In the RV there is a less marked reduction in volumes at 10 while at 20 mcg dobutamine there is no significant change in ESV in a sub-group (p=0.63

    Numerosity and density judgments: Biases for area but not for volume

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    International audienceHuman observers can rapidly judge the number of items in a scene. This ability is underpinned by specific mechanisms encoding number or density. We investigated whether judgments of number and density are biased by a change in volume, as they are by a change in area. Stimuli were constructed using nonoverlapping black and white luminance-defined dots. An eight-mirror Wheatstone stereoscope was used to present the dots as though in a volume. Using a temporal two-alternative forced-choice (2AFC) task and the Method of Constant Stimuli (MOCS), we measured the precision and bias (PSE shift) of numerosity and density judgments, separately, for stimuli differing in area or volume. For two-dimensional (2-D) stimuli, consistent with previous literature, perceived density was biased as area increased. However, perceived number was not. For three-dimensional (3-D) stimuli, despite a vivid impression of the dots filling a cylindrical volume, there was no bias in perceived density or number as volume increased. A control experiment showed that all of our observers could easily perceive disparity in our stimuli. Our findings reveal that number and density judgments that are biased by area are not similarly biased by volume changes

    Prescription drug monitoring program data tracking of opioid addiction treatment outcomes in integrated dual diagnosis care involving injectable naltrexone

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    BACKGROUND AND OBJECTIVES: Fourfold increases in opioid prescribing and dispensations over 2 decades in the U.S. has paralleled increases in opioid addictions and overdoses, requiring new preventative, diagnostic, and treatment strategies. This study examines Prescription Drug Monitoring Program (PDMP) tracking as a novel measure of opioid addiction treatment outcomes in a university-affiliated integrated mental health-addiction treatment clinic. METHODS: Repeated measure parametrics examined PDMP and urine drug screening (UDS) data before and after first injection for all patients (N = 68) who received at least one long-acting naltrexone injection (380 mg/IM) according to diagnostic groupings of having either (i) alcohol (control); (ii) opioid; or (iii) combined alcohol and opioid use disorders. RESULTS: There were no group differences post-injection in treatment days, injections delivered, or treatment service encounters. UDS and PDMP measures of opioid exposures were greater in opioid compared to alcohol-only patients. Post-first injection, UDS's positive for opioids declined (p < .05) along with PDMP measures of opioid prescriptions (p < .001), doses (p < .01), types (p < .001), numbers of dispensing prescribers (p < .001) and pharmacies (p < .001). Opioid patients without alcohol disorders showed the best outcomes with 50% to 80% reductions in PDMP-measures of opioids, down to levels of alcohol-only patients. CONCLUSIONS: This study shows PDMP utility for measuring opioid addiction treatment outcomes, supporting the routine use of PDMPs in clinical and research settings. SCIENTIFIC SIGNIFICANCE: These findings demonstrate that opioid addiction in patients with complex addictions and mental illnesses comorbidities can show effective treatment responses as measured by PDMP tracking of decreases in opioid prescriptions to those patients. (Am J Addict 2016;25:557-564)

    The effect of Warm Dark Matter on galaxy properties: constraints from the stellar mass function and the Tully-Fisher relation

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    In this paper we combine high resolution N-body simulations with a semi analytical model of galaxy formation to study the effects of a possible Warm Dark Matter (WDM) component on the observable properties of galaxies. We compare three WDM models with a dark matter mass of 0.5, 0.75 and 2.0 keV, with the standard Cold Dark Matter case. For a fixed set of parameters describing the baryonic physics the WDM models predict less galaxies at low (stellar) masses, as expected due to the suppression of power on small scales, while no substantial difference is found at the high mass end. However these differences in the stellar mass function, vanish when different set of parameters are used to describe the (largely unknown) galaxy formation processes. We show that is possible to break this degeneracy between DM properties and the parameterization of baryonic physics by combining observations on the stellar mass function with the Tully-Fisher relation (the relation between stellar mass and the rotation velocity at large galactic radii as probed by resolved HI rotation curves). WDM models with a too warm candidate (m<0.75 keV) cannot simultaneously reproduce the stellar mass function and the Tully-Fisher relation. We conclude that accurate measurements of the galaxy stellar mass function and the link between galaxies and dark matter haloes down to the very low-mass end can give very tight constraints on the nature of DM candidates.Comment: 8 pages, 5 figures, minor changes, accepted for publication on Ap
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