683 research outputs found
Middle meningeal artery with multiple pseudoaneurysms and their management
Pseudoaneurysms of the middle meningeal artery (MMA) are a rare pathology. Here we present a case of a patient with a non-surgical traumatic subdural hemorrhage, whom was found to have three unruptured aneurysmal lesions along the middle meningeal artery. The patient underwent successful endovascular embolization of his MMA and its aneurysmal lesions. This case presents a unique morphology of a rare disease treated safely and effectively using endovascular embolization
Risk Mitigation Approach to Commercial Resupply to the International Space Station
In August 2006, NASA awarded Space Act Agreements (SAAs) for Commercial Orbital Transportation Services (COTS) under the Commercial Crew and Cargo Project Office at Johnson Space Center. One of the goals of the SAAs is to facilitate U.S. private industry demonstration of cargo transportation capabilities, ultimately achieving reliable, cost effective access to low-Earth orbit (LEO). Each COTS provider is required to complete International Space Stations (ISS) Integration activities, which includes meeting the physical and functional interfaces and interface requirements between the ISS and COTS vehicles. These requirements focus on the areas of risk to the ISS during rendezvous and proximity operations, as well as the integration operations while the COTS vehicle is berthed to the ISS. On December 23, 2008, NASA awarded Commercial Resupply Service (CRS) contracts to provide resupply services to the ISS, following the Shuttle retirement. In addition to performing any ISS Integration activities, NASA will be performing independent assessments of the launch vehicle and orbital vehicle to evaluate the readiness of the contractor to deliver NASA cargo safely to the ISS. This paper will address the activities NASA Centers, both JSC and KSC, in the oversight and insight function over commercial visiting vehicles to the ISS
Endovascular treatment of cervical myelopathy from brachiocephalic venous stenosis.
Central venous stenosis is a rare cause of neurologic pathology. Here we present a case of brachiocephalic vein stenosis causing cervical myelopathy through venous engorgement. Our patient was a 51-y/o male who presented with ambulatory dysfunction so he was evaluated for cervical myelopathy. Imaging revealed cord compression from venous engorgement and brachiocephalic vein stenosis. He was treated with angioplasty and vessel stenting which significantly improved flow on postintervention imaging. In conclusion, preoperative vascular imaging should be considered in myelopathic patients as it can detect this rare but dangerous etiology
A 2D Quantum Walk Simulation of Two-Particle Dynamics
Multi-dimensional quantum walks can exhibit highly non-trivial topological
structure, providing a powerful tool for simulating quantum information and
transport systems. We present a flexible implementation of a 2D optical quantum
walk on a lattice, demonstrating a scalable quantum walk on a non-trivial graph
structure. We realized a coherent quantum walk over 12 steps and 169 positions
using an optical fiber network. With our broad spectrum of quantum coins we
were able to simulate the creation of entanglement in bipartite systems with
conditioned interactions. Introducing dynamic control allowed for the
investigation of effects such as strong non-linearities or two-particle
scattering. Our results illustrate the potential of quantum walks as a route
for simulating and understanding complex quantum systems
Spatio-spectral characteristics of parametric down-conversion in waveguide arrays
High dimensional quantum states are of fundamental interest for quantum
information processing. They give access to large Hilbert spaces and, in turn,
enable the encoding of quantum information on multiple modes. One method to
create such quantum states is parametric down-conversion (PDC) in waveguide
arrays (WGAs) which allows for the creation of highly entangled photon-pairs in
controlled, easily accessible spatial modes, with unique spectral properties.
In this paper we examine both theoretically and experimentally the PDC process
in a lithium niobate WGA. We measure the spatial and spectral properties of the
emitted photon-pairs, revealing strong correlations between spectral and
spatial degrees of freedom of the created photons. Our measurements show that,
in contrast to prior theoretical approaches, spectrally dependent coupling
effects have to be taken into account in the theory of PDC in WGAs. To
interpret the results, we developed a theoretical model specifically taking
into account spectrally dependent coupling effects, which further enables us to
explore the capabilities and limitations for engineering the spatial
correlations of the generated quantum states.Comment: 26 pages, 11 figure
The contribution of caregiver psychosocial factors to distress associated with behavioural and psychological symptoms in dementia
Copyright © 2016 John Wiley & Sons, Ltd. Objective: The objective of the study is to examine caregiver factors as predictors of BPSD-related distress and their potential mechanisms. Method: Informal caregivers of people with dementia (n = 157) recruited from 28 community mental health teams in six NHS Trusts across England completed questionnaires regarding psychosocial factors (relationship quality, competence, guilt, health-related quality of life in the caregiver and person with dementia, reactivity to behavioural and psychological symptoms in dementia [BPSD] and burden) and frequency of BPSD. Analyses of BPSD-related distress include hierarchical multiple regression, mediation, moderation and path analysis. Results: Caregiver psychosocial factors explained 56% of the variance in BPSD-related distress. After controlling for these factors, frequency of BPSD was not a significant predictor of BPSD-related distress. Caregiver reactivity to BPSD, burden, competence and relationship quality directly influenced BPSD-related distress. Guilt influenced distress indirectly via competence, burden and reactivity to BPSD. The final model accounted for 41% of the variance in BPSD-related distress and achieved a good fit to the data (χ 2 = 23.920, df = 19, p = 0.199). Conclusions: Caregiver psychosocial factors including sense of competence, guilt, burden and reactivity to BPSD contribute to BPSD-related distress. Tailored interventions for managing behaviour problems in family settings could focus on these factors associated with BPSD-related distress to minimise distress in families. Copyright © 2016 John Wiley & Sons, Ltd
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Serum albumin and hospitalization among pediatric patients with end-stage renal disease who started dialysis therapy.
BackgroundHypoalbuminemia is a strong predictor of hospitalization and mortality among adult dialysis patients. However, data are scant on the association between serum albumin and hospitalization among children new to dialysis.MethodsIn a retrospective cohort study of children 1-17 years old with end-stage renal disease receiving dialysis therapy in a large US dialysis organization 2007-2011, we examined the association of serum albumin with hospitalization frequency and total hospitalization days using a negative binomial regression model.ResultsAmong 416 eligible patients, median (interquartile range) age was 14 (10-16) years and mean ± SD baseline serum albumin level was 3.7 ± 0.8 g/dL. Two hundred sixty-six patients (64%) were hospitalized during follow-up with an incidence rate of 2.2 (95%CI, 1.9-2.4) admissions per patient-year. There was a U-shaped association between serum albumin and hospitalization frequency; hospitalization rates (95%CI) were 2.7 (2.2-3.2), 1.9 (1.5-2.4), 1.6 (1.3-1.9), and 2.7 (1.7-3.6) per patient-year among patients with serum albumin levels < 3.5, 3.5- < 4.0, 4.0- < 4.5, and ≥ 4.5 g/dL, respectively. Case mix-adjusted hospitalization incidence rate ratios (IRRs) (95%CI) were 1.63 (1.24-2.13), 1.32 (1.10-1.58), and 1.25 (1.06-1.49) at serum albumin levels 3.0, 3.5, and 4.5 g/dL, respectively (reference: 4.0 g/dL). Similar trends were observed in hospitalization days. These associations remained robust against further adjustment for laboratory variables associated with malnutrition and inflammation.ConclusionsBoth high and low serum albumin were associated with higher hospitalization in children starting dialysis. Because the observed association is novel and not fully explainable especially for high serum albumin levels, interpreting the results requires caution and further studies are needed to confirm and elucidate this association before clinical recommendations are made
Synthesis of the originally proposed structures of elatenyne and an enyne from Laurencia majuscula
A bidirectional synthesis of the originally proposed structures for the natural products elatenyne and a chloroenyne from Laurencia majuscula is described along with a reassessment of the structures of the halogenated enynes based upon a C-13 NMR chemical shift/structure correlation
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