1,860 research outputs found

    Development of a Light-Weight, Reliable, Booster System for SHELS-Launched Payloads

    Get PDF
    Small satellite missions are often used to support low-cost space missions demonstrating new technologies. An economical source of low-cost space lift is to fly these satellites as secondary payloads aboard the Space Shuttle. The Shuttle has accommodations for flying these payloads using the Shuttle Hitchhiker Experiment Launch System (SHELS). While the relative costs for a Shuttle launch are at least an order of magnitude below the cost of a dedicated Expendable Launch Vehicle (ELV), final orbit altitude selection is limited to Shuttle mission goals. The Air Force Space Test Program (STP) is responsible for flying the Space Experiments Review Board (SERB) recommended experiments on a level-of-effort basis. Low-cost space lift is crucial to maximizing the number of SERB payloads that STP can support. Unfortunately, the typical Shuttle orbit does not provide a high enough orbit to guarantee the oneyear orbital lifetime required to meet STP mission objectives. A low-cost, autonomous STP Transfer Upper stage, Guided (TUG) that can boost an STP payload from a typical Shuttle orbit to a higher, longer duration orbit would allow STP to take advantage of the low-cost space lift provided by the Shuttle and still meet their mission requirements. The Air Force Research Laboratory Space Vehicles Directorate (AFRL/VS) is pursuing a solution to fulfill STP’s satellite lifting requirements by developing a low-cost, lightweight, reliable, strap-on propulsion module using several Small Business Innovative Research (SBIR) contracts focused on various parts of the TUG system. The Shuttle Expendable Rocket for Payload Augmentation (SHERPA) program will integrate all of these SBIR programs to meet the STP TUG requirement. The TUG system would be composed of several technologies being developed or already developed by AFRL/VS such as separation systems, guidance systems, propulsion modules, and modular bus architecture. The TUG would be re-startable for multiple orbit changes, station keeping, or deorbiting at the completion of a mission. Three versions of the TUG are envisioned. The first is a simple propulsion module that uses the satellite\u27s Attitude Control System (ACS) and Guidance, Navigation, and Control (GN&C) to provide stack guidance. The second is a fully autonomous TUG that lifts the payload to the higher orbit as cargo, separates from the payload, and then accomplishes a collision avoidance maneuver and propellant burn after payload separation. The third configuration is an autonomous TUG with a long duration module that allow experiments to use the TUG\u27s ACS, GN&C, and power systems in the intended final orbit. There are many challenges in the development of this vehicle. The most difficult of these is meeting the man-rating requirements of the Shuttle. All critical systems must have triple redundancy to ensure that the system does not threaten the Shuttle, its crew, or its mission. Another complication is producing a structure that meets the strict mass and volume restrictions of the SHELS system. Integration is als o a challenge, as many contractors and technologies are brought together under this program

    Are autistic traits measured equivalently in individuals with and without an Autism Spectrum Disorder?:An invariance analysis of the Autism Spectrum Quotient Short Form

    Get PDF
    It is common to administer measures of autistic traits to those without autism spectrum disorders (ASDs) with, for example, the aim of understanding autistic personality characteristics in non-autistic individuals. Little research has examined the extent to which measures of autistic traits actually measure the same traits in the same way across those with and without an ASD. We addressed this question using a multi-group confirmatory factor invariance analysis of the Autism Quotient Short Form (AQ-S: Hoekstra et al. in J Autism Dev Disord 41(5):589-596, 2011) across those with (n = 148) and without (n = 168) ASD. Metric variance (equality of factor loadings), but not scalar invariance (equality of thresholds), held suggesting that the AQ-S measures the same latent traits in both groups, but with a bias in the manner in which trait levels are estimated. We, therefore, argue that the AQ-S can be used to investigate possible causes and consequences of autistic traits in both groups separately, but caution is due when combining or comparing levels of autistic traits across the two group

    First report of generalized face processing difficulties in möbius sequence.

    Get PDF
    Reverse simulation models of facial expression recognition suggest that we recognize the emotions of others by running implicit motor programmes responsible for the production of that expression. Previous work has tested this theory by examining facial expression recognition in participants with Möbius sequence, a condition characterized by congenital bilateral facial paralysis. However, a mixed pattern of findings has emerged, and it has not yet been tested whether these individuals can imagine facial expressions, a process also hypothesized to be underpinned by proprioceptive feedback from the face. We investigated this issue by examining expression recognition and imagery in six participants with Möbius sequence, and also carried out tests assessing facial identity and object recognition, as well as basic visual processing. While five of the six participants presented with expression recognition impairments, only one was impaired at the imagery of facial expressions. Further, five participants presented with other difficulties in the recognition of facial identity or objects, or in lower-level visual processing. We discuss the implications of our findings for the reverse simulation model, and suggest that facial identity recognition impairments may be more severe in the condition than has previously been noted

    Spin and Chirality Effects in Antler-Topology Processes at High Energy e+ee^+e^- Colliders

    Full text link
    We perform a model-independent investigation of spin and chirality correlation effects in the antler-topology processes e+eP+P(+D0)(Dˉ0)e^+e^-\to\mathcal{P}^+\mathcal{P}^-\to (\ell^+ \mathcal{D}^0) (\ell^-\mathcal{\bar{D}}^0) at high energy e+ee^+e^- colliders with polarized beams. Generally the production process e+eP+Pe^+e^-\to\mathcal{P}^+\mathcal{P}^- can occur not only through the ss-channel exchange of vector bosons, V0\mathcal{V}^0, including the neutral Standard Model (SM) gauge bosons, γ\gamma and ZZ, but also through the ss- and tt-channel exchanges of new neutral states, S0\mathcal{S}^0 and T0\mathcal{T}^0, and the uu-channel exchange of new doubly-charged states, U\mathcal{U}^{--}. The general set of (non-chiral) three-point couplings of the new particles and leptons allowed in a renormalizable quantum field theory is considered. The general spin and chirality analysis is based on the threshold behavior of the excitation curves for P+P\mathcal{P}^+\mathcal{P}^- pair production in e+ee^+e^- collisions with longitudinal and transverse polarized beams, the angular distributions in the production process and also the production-decay angular correlations. In the first step, we present the observables in the helicity formalism. Subsequently, we show how a set of observables can be designed for determining the spins and chiral structures of the new particles without any model assumptions. Finally, taking into account a typical set of approximately chiral invariant scenarios, we demonstrate how the spin and chirality effects can be probed experimentally at a high energy e+ee^+e^- collider.Comment: 50 pages, 14 figures, 6 tables, matches version published in EPJ

    Genomic surveillance of Acinetobacter baumannii in the Philippines, 2013-2014

    Get PDF
    This work was supported by a Newton Fund award from the Medical Research Council (UK) MR/N019296/1 and the Philippine Council for Health Research and Development. This work was also partially supported by research grant U01CA207167 from the U.S. National Institutes of Health. S.A. and D.M.A. were additionally supported by the National Institute for Health Research (UK) Global Health Research Unit on genomic Surveillance of AMR (16_136_111) and by the Centre for Genomic Pathogen Surveillance.Objective: Acinetobacter baumannii is an opportunistic nosocomial pathogen that has increasingly become resistant to carbapenems worldwide. In the Philippines, rates of carbapenem resistance and multidrug resistance are above 50%. We undertook a genomic study of carbapenem-resistant A. baumannii in the Philippines to characterize the population diversity and antimicrobial resistance mechanisms. Methods: We sequenced the whole genomes of 117 A. baumannii isolates recovered by 16 hospitals in the Philippines between 2013 and 2014. From the genome sequences, we determined the multilocus sequence type, presence of acquired determinants of antimicrobial resistance and relatedness between isolates. We also compared the phenotypic and genotypic resistance results. Results: Carbapenem resistance was mainly explained by acquisition of the class-D beta-lactamase gene bla(OXA-23). The concordance between phenotypic and genotypic resistance to imipenem was 98.15%, and it was 94.97% overall for the seven antibiotics analysed. Twenty-two different sequence types were identified, including 7 novel types. The population was dominated by the high-risk international clone 2 (i.e. clonal complex 92), in particular by ST195 and ST208 and their single locus variants. Using whole-genome sequencing, we identified local clusters representing potentially undetected nosocomial outbreaks, as well as multi-hospital clusters that indicated interhospital dissemination. Comparison with global genomes suggested that the establishment of carbapenem-resistant international clone 2 in the Philippines is likely the result of clonal expansion and geographical dissemination, and at least partly explained by inadequate hospital infection control and prevention. Discussion: This is the first extensive genomic study of carbapenem-resistant A. baumannii in the Philippines, and it underscores the importance of hospital infection control and prevention measures to contain high-risk clones.Publisher PDFPeer reviewe

    Combined sedation with midazolam/propofol for gastrointestinal endoscopy in elderly patients

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Although gastrointestinal endoscopy with sedation is increasingly performed in elderly patients, data on combined sedation with midazolam/propofol are very limited for this age group.</p> <p>Methods</p> <p>We retrospectively analyzed 454 endoscopic procedures in 347 hospitalized patients ≥ 70 years who had received combined sedation with midazolam/propofol. 513 endoscopic procedures in 397 hospitalized patients < 70 years during the observation period served as controls. Characteristics of endoscopic procedures, co-morbidity, complications and mortality were compared.</p> <p>Results</p> <p>Elderly patients had a higher level of co-morbidity and needed lower mean propofol doses for sedation. We observed no major complication and no difference in the number of minor complications. The procedure-associated mortality was 0%; the 28-day mortality was significantly higher in the elderly (2.9% vs. 1.0%).</p> <p>Conclusions</p> <p>In this study on elderly patients with high level co-morbidity, a favourable safety profile was observed for a combined sedation with midazolam/propofol with a higher sensitivity to propofol in the elderly.</p

    High spatial and temporal resolution wide-field imaging of neuron activity using quantum NV-diamond

    Get PDF
    A quantitative understanding of the dynamics of biological neural networks is fundamental to gaining insight into information processing in the brain. While techniques exist to measure spatial or temporal properties of these networks, it remains a significant challenge to resolve the neural dynamics with subcellular spatial resolution. In this work we consider a fundamentally new form of wide-field imaging for neuronal networks based on the nanoscale magnetic field sensing properties of optically active spins in a diamond substrate. We analyse the sensitivity of the system to the magnetic field generated by an axon transmembrane potential and confirm these predictions experimentally using electronically-generated neuron signals. By numerical simulation of the time dependent transmembrane potential of a morphologically reconstructed hippocampal CA1 pyramidal neuron, we show that the imaging system is capable of imaging planar neuron activity non-invasively at millisecond temporal resolution and micron spatial resolution over wide-fields

    Edoxaban: an update on the new oral direct factor Xa inhibitor.

    Get PDF
    Edoxaban is a once-daily oral anticoagulant that rapidly and selectively inhibits factor Xa in a concentration-dependent manner. This review describes the extensive clinical development program of edoxaban, including phase III studies in patients with non-valvular atrial fibrillation (NVAF) and symptomatic venous thromboembolism (VTE). The ENGAGE AF-TIMI 48 study (N = 21,105; mean CHADS2 score 2.8) compared edoxaban 60 mg once daily (high-dose regimen) and edoxaban 30 mg once daily (low-dose regimen) with dose-adjusted warfarin [international normalized ratio (INR) 2.0-3.0] and found that both regimens were non-inferior to warfarin in the prevention of stroke and systemic embolism in patients with NVAF. Both edoxaban regimens also provided significant reductions in the risk of hemorrhagic stroke, cardiovascular mortality, major bleeding and intracranial bleeding. The Hokusai-VTE study (N = 8,292) in patients with symptomatic VTE had a flexible treatment duration of 3-12 months and found that following initial heparin, edoxaban 60 mg once daily was non-inferior to dose-adjusted warfarin (INR 2.0-3.0) for the prevention of recurrent VTE, and also had a significantly lower risk of bleeding events. Both studies randomized patients at moderate-to-high risk of thromboembolic events and were further designed to simulate routine clinical practice as much as possible, with edoxaban dose reduction (halving dose) at randomisation or during the study if required, a frequently monitored and well-controlled warfarin group, a well-monitored transition period at study end and a flexible treatment duration in Hokusai-VTE. Given the phase III results obtained, once-daily edoxaban may soon be a key addition to the range of antithrombotic treatment options

    Assessing Internet addiction using the parsimonious Internet addiction components model - a preliminary study [forthcoming]

    Get PDF
    Internet usage has grown exponentially over the last decade. Research indicates that excessive Internet use can lead to symptoms associated with addiction. To date, assessment of potential Internet addiction has varied regarding populations studied and instruments used, making reliable prevalence estimations difficult. To overcome the present problems a preliminary study was conducted testing a parsimonious Internet addiction components model based on Griffiths’ addiction components (2005), including salience, mood modification, tolerance, withdrawal, conflict, and relapse. Two validated measures of Internet addiction were used (Compulsive Internet Use Scale [CIUS], Meerkerk et al., 2009, and Assessment for Internet and Computer Game Addiction Scale [AICA-S], Beutel et al., 2010) in two independent samples (ns = 3,105 and 2,257). The fit of the model was analysed using Confirmatory Factor Analysis. Results indicate that the Internet addiction components model fits the data in both samples well. The two sample/two instrument approach provides converging evidence concerning the degree to which the components model can organize the self-reported behavioural components of Internet addiction. Recommendations for future research include a more detailed assessment of tolerance as addiction component
    corecore