803 research outputs found
Microwave-mediated synthesis of N-methyliminodiacetic acid (MIDA) boronates
A library of over 20, mainly aryl or heteroaryl, N-methyliminodiacetic acid (MIDA) boronates have been synthesised. A rapid microwave-mediated (MW) method (5–10 min) has been developed using polyethylene glycol 300 (PEG 300) as solvent. However, acetonitrile (MeCN) and dimethylformamide (DMF) were found to be alternative solvents, the latter especially for 2-substituted aryl boronic acids
Impaired Hyperemic Response to Exercise Post Stroke
Individuals with chronic stroke have reduced perfusion of the paretic lower limb at rest; however, the hyperemic response to graded muscle contractions in this patient population has not been examined. This study quantified blood flow to the paretic and non-paretic lower limbs of subjects with chronic stroke after submaximal contractions of the knee extensor muscles and correlated those measures with limb function and activity. Ten subjects with chronic stroke and ten controls had blood flow through the superficial femoral artery quantified with ultrasonography before and immediately after 10 second contractions of the knee extensor muscles at 20, 40, 60, and 80% of the maximal voluntary contraction (MVC) of the test limb. Blood flow to the paretic and non-paretic limb of stroke subjects was significantly reduced at all load levels compared to control subjects even after normalization to lean muscle mass. Of variables measured, increased blood flow after an 80% MVC was the single best predictor of paretic limb strength, the symmetry of strength between the paretic and non-paretic limbs, coordination of the paretic limb, and physical activity. The impaired hemodynamic response to high intensity contractions was a better predictor of lower limb function than resting perfusion measures. Stroke-dependent weakness and atrophy of the paretic limb do not explain the reduced hyperemic response to muscle contraction alone as the response is similarly reduced in the non-paretic limb when compared to controls. These data may suggest a role for perfusion therapies to optimize rehabilitation post stroke
Cold atom confinement in an all-optical dark ring trap
We demonstrate confinement of Rb atoms in a dark, toroidal optical
trap. We use a spatial light modulator to convert a single blue-detuned
Gaussian laser beam to a superposition of Laguerre-Gaussian modes that forms a
ring-shaped intensity null bounded harmonically in all directions. We measure a
1/e spin-relaxation lifetime of ~1.5 seconds for a trap detuning of 4.0 nm. For
smaller detunings, a time-dependent relaxation rate is observed. We use these
relaxation rate measurements and imaging diagnostics to optimize trap alignment
in a programmable manner with the modulator. The results are compared with
numerical simulations.Comment: 5 pages, 4 figure
Magnetically-controlled velocity selection in a cold atom sample using stimulated Raman transitions
We observe velocity-selective two-photon resonances in a cold atom cloud in
the presence of a magnetic field. We use these resonances to demonstrate a
simple magnetometer with sub-mG resolution. The technique is particularly
useful for zeroing the magnetic field and does not require any additional laser
frequencies than are already used for standard magneto-optical traps. We verify
the effects using Faraday rotation spectroscopy.Comment: 5 pages, 6 figure
Costs of preparing to implement a virtual reality job interview training programme in a community mental health agency: A budget impact analysis
Rational, aims and objectivesIndividual Placement and Support (IPS) is an evidence based strategy for facilitating employment among adults with severe mental illness (SMI) where staff may lead mock job interviews to prepare clients for real- world interviews (a method with limited scalability and cost effectiveness). A virtual reality job interview training program (VR- JIT)- delivered via the internet- has demonstrated efficacy for increasing employment among adults with SMI. Now, VR- JIT is being implemented with a community mental health agency (CMHA) and evaluated for its effectiveness within IPS. This study is a budget impact analysis, evaluating the costs of preparing a CMHA to implement VR- JIT.MethodImplementation preparation occurred over 7 months from October 1, 2016 to April 30, 2017. CMHA staff (n- =- 15) and external research partners (n- =- 3) tracked their hours completing implementation preparation activities. Salaries plus a 28% fringe benefit rate were used to derive a per- hour salary amount for each individual and applied to each activity. Non- labor equipment costs were obtained from purchase receipts. A budget impact analysis evaluated the expenditures associated with preparing the CMHA to implement VRJIT.ResultsThe total implementation preparation costs equaled 22,882 and non- labor costs equaled $2,600. In total, 655 person- hours were spent preparing for VR- JIT implementation (e.g., preparing lab space, training, and supervising operations).ConclusionsThis study presents an initial evaluation of the budget impact of preparing to implement VR- JIT in a CMHA. Cost considerations for future implementation preparation will be discussed. Given that the cost to prepare to implement an intervention can hinder its adoption, results provide an important analysis for decision- makers that may enhance uptake. Future work will determine the cost- effectiveness of VR- JIT implemented within IPS. This study is registered at http://clinicaltrials.gov, NCT- =- 03049813, - Virtual Reality Job Interview Training: An Enhancement to Supported Employment in Severe Mental Illness.-Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156238/2/jep13292.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156238/1/jep13292_am.pd
Empirical Models of Transitions between Coral Reef States: Effects of Region, Protection, and Environmental Change
There has been substantial recent change in coral reef communities. To date, most analyses have focussed on static patterns or changes in single variables such as coral cover. However, little is known about how community-level changes occur at large spatial scales. Here, we develop Markov models of annual changes in coral and macroalgal cover in the Caribbean and Great Barrier Reef (GBR) regions
Aneurysm permeability following coil embolization: packing density and coil distribution
BACKGROUND: Rates of durable aneurysm occlusion following coil embolization vary widely, and a better understanding of coil mass mechanics is desired. The goal of this study is to evaluate the impact of packing density and coil uniformity on aneurysm permeability.
METHODS: Aneurysm models were coiled using either Guglielmi detachable coils or Target coils. The permeability was assessed by taking the ratio of microspheres passing through the coil mass to those in the working fluid. Aneurysms containing coil masses were sectioned for image analysis to determine surface area fraction and coil uniformity.
RESULTS: All aneurysms were coiled to a packing density of at least 27%. Packing density, surface area fraction of the dome and neck, and uniformity of the dome were significantly correlated (p \u3c 0.05). Hence, multivariate principal components-based partial least squares regression models were used to predict permeability. Similar loading vectors were obtained for packing and uniformity measures. Coil mass permeability was modeled better with the inclusion of packing and uniformity measures of the dome (r(2)=0.73) than with packing density alone (r(2)=0.45). The analysis indicates the importance of including a uniformity measure for coil distribution in the dome along with packing measures.
CONCLUSIONS: A densely packed aneurysm with a high degree of coil mass uniformity will reduce permeability
Five millennia of surface temperatures and ice core bubble characteristics from the WAIS Divide deep core, West Antarctica
Bubble number densities from the West Antarctic Ice Sheet (WAIS) Divide deep core in West Antarctica record relatively stable temperatures during the middle Holocene followed by late Holocene cooling. We measured bubble number density, shape, size, and arrangement on new samples of the main WAIS Divide deep core WDC06A from similar to 580m to similar to 1600 depth. The bubble size, shape, and arrangement data confirm that the samples satisfy the requirements for temperature reconstructions. A small correction for cracks formed after core recovery allows extension of earlier work through the brittle ice zone, and a site-specific calibration reduces uncertainties. Using an independently constructed accumulation rate history and a steady state bubble number density model, we determined a temperature reconstruction that agrees closely with other independent estimates, showing a stable middle Holocene, followed by a cooling of similar to 1.25 degrees C in the late Holocene. Over the last similar to 5 millennia, accumulation has been higher during warmer times by similar to 12%degrees C-1, somewhat stronger than for thermodynamic control alone, suggesting dynamic processes
The beginning of time? Evidence for catastrophic drought in Baringo in the early nineteenth century
New developments in the collection of palaeo-data over the past two decades have transformed our understanding of climate and environmental history in eastern Africa. This article utilises instrumental and proxy evidence of historical lake-level fluctuations from Baringo and Bogoria, along with other Rift Valley lakes, to document the timing and magnitude of hydroclimate variability at decadal to century time scales since 1750. These data allow us to construct a record of past climate variation not only for the Baringo basin proper, but also across a sizable portion of central and northern Kenya. This record is then set alongside historical evidence, from oral histories gathered amongst the peoples of northern Kenya and the Rift Valley and from contemporary observations recorded by travellers through the region, to offer a reinterpretation of human activity and its relationship to environmental history in the nineteenth century. The results reveal strong evidence of a catastrophic drought in the early nineteenth century, the effects of which radically alters our historical understanding of the character of settlement, mobility and identity within the Baringo–Bogoria basin
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