79 research outputs found

    Real-time diffuse optical tomography using reduced-order light propagation models based on a priori anatomical and functional information

    Get PDF
    This paper proposes a new fast 3D image reconstruction algorithm for Diffuse Optical Tomography using reduced order polynomial mappings from the space of optical tissue parameters into the space of flux measurements at the detector locations. The polynomial mappings are constructed through an iterative estimation process involving structure detection, parameter estimation and cross-validation using data generated by simulating a diffusion approximation of the radiative transfer equation incorporating a priori anatomical and functional information provided by MR scans and prior psychological evidence. Numerical simulation studies demonstrate that reconstructed images are remarkably similar in quality as those obtained using the standard approach, but obtained at a fraction of the time

    Illusory Decoherence

    Full text link
    If a quantum experiment includes random processes, then the results of repeated measurements can appear consistent with irreversible decoherence even if the system's evolution prior to measurement was reversible and unitary. Two thought experiments are constructed as examples.Comment: 10 pages, 3 figure

    Long-Term Consequences of Methamphetamine Exposure in Young Adults Are Exacerbated in Glial Cell Line-Derived Neurotrophic Factor Heterozygous Mice

    Get PDF
    Methamphetamine abuse in young adults has long-term deleterious effects on brain function that are associated with damage to monoaminergic neurons. Administration of glial cell line-derived neurotrophic factor (GDNF) protects dopamine neurons from the toxic effects of methamphetamine in animal models. Therefore, we hypothesized that a partial GDNF gene deletion would increase the susceptibility of mice to methamphetamine neurotoxicity during young adulthood and possibly increase age-related deterioration of behavior and dopamine function. Two weeks after a methamphetamine binge (4 x 10 mg/kg, i.p., at 2 h intervals), GDNF +/- mice had a significantly greater reduction of tyrosine hydroxylase immunoreactivity in the medial striatum, a proportionally greater depletion of dopamine and 3,4-dihydroxyphenylacetic acid (DOPAC) levels in the striatum, and a greater increase in activated microglia in the substantia nigra than wild-type mice. At 12 months of age, methamphetamine-treated GDNF +/- mice exhibited less motor activity and lower levels oftyrosine hydroxylase-immunoreactivity, dopamine, DOPAC, and serotoninthanwild-typemice. Greater striatal dopaminetransporter activity in GDNF +/- mice may underlie their differential response to methamphetamine. These data suggest the possibility that methamphetamine use in young adults, when combined with lower levels of GDNF throughout life, may precipitate the appearance of parkinsonian-like behaviors during aging

    Interventions aimed at improving the nursing work environment: a systematic review

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Nursing work environments (NWEs) in Canada and other Western countries have increasingly received attention following years of restructuring and reported high workloads, high absenteeism, and shortages of nursing staff. Despite numerous efforts to improve NWEs, little is known about the effectiveness of interventions to improve NWEs. The aim of this study was to review systematically the scientific literature on implemented interventions aimed at improving the NWE and their effectiveness.</p> <p>Methods</p> <p>An online search of the databases CINAHL, Medline, Scopus, ABI, Academic Search Complete, HEALTHstar, ERIC, Psychinfo, and Embase, and a manual search of Emerald and Longwoods was conducted. (Quasi-) experimental studies with pre/post measures of interventions aimed at improving the NWE, study populations of nurses, and quantitative outcome measures of the nursing work environment were required for inclusion. Each study was assessed for methodological strength using a quality assessment and validity tool for intervention studies. A taxonomy of NWE characteristics was developed that would allow us to identify on which part of the NWE an intervention targeted for improvement, after which the effects of the interventions were examined.</p> <p>Results</p> <p>Over 9,000 titles and abstracts were screened. Eleven controlled intervention studies met the inclusion criteria, of which eight used a quasi-experimental design and three an experimental design. In total, nine different interventions were reported in the included studies. The most effective interventions at improving the NWE were: primary nursing (two studies), the educational toolbox (one study), the individualized care and clinical supervision (one study), and the violence prevention intervention (one study).</p> <p>Conclusions</p> <p>Little is known about the effectiveness of interventions aimed at improving the NWE, and published studies on this topic show weaknesses in their design. To advance the field, we recommend that investigators use controlled studies with pre/post measures to evaluate interventions that are aimed at improving the NWE. Thereby, more evidence-based knowledge about the implementation of interventions will become available for healthcare leaders to use in rebuilding nursing work environments.</p

    TEAM-UP for quality: a cluster randomized controlled trial protocol focused on preventing pressure ulcers through repositioning frequency and precipitating factors

    Get PDF
    Background: Pressure ulcers/injuries (PrUs), a critical concern for nursing homes (NH), are responsible for chronic wounds, amputations, septic infections, and premature deaths. PrUs occur most commonly in older adults and NH residence is a risk factor for their development, with at least one of every nine U.S. NH residents experiencing a PrU and many NHs having high incidence and prevalence rates, in some instances well over 20%. PrU direct treatment costs are greater than prevention costs, making prevention-focused protocols critical. Current PrU prevention protocols recommend repositioning residents at moderate, high, and severe risk every 2 h. The advent of visco- elastic (VE) high-density foam support-surfaces over the past decade may now make it possible to extend the repositioning interval to every 3 or 4 h without increasing PrU development. The TEAM-UP (Turn Everyone And Move for Ulcer Prevention) study aims to determine: 1) whether repositioning interval can be extended for NH residents without compromising PrU incidence and 2) how changes in medical severity interact with changes in risk level and repositioning schedule to predict PrU development. Methods: In this proposed cluster randomized study, 9 NHs will be randomly assigned to one of three repositioning intervals (2, 3, or 4 h) for a 4-week period. Each enrolled site will use a single NH-wide repositioning interval as the standard of care for residents at low, moderate, and high risk of PrU development (N = 951) meeting the following criteria: minimum 3-day stay, without PrUs, no adhesive allergy, and using VE support surfaces (mattresses). An FDA-cleared patient monitoring system that records position/movement of these residents via individual wireless sensors will be used to visually cue staff when residents need repositioning and document compliance with repositioning protocols. Discussion: This study will advance knowledge about repositioning frequency and clinically assessed PrU risk level in relation to PrU incidence and medical severity. Outcomes of this research will contribute to future guidelines for more precise preventive nursing practices and refinement of PrU prevention guidelines. Trial registration: Clinical Trial Registration: NCT02996331

    Models of classroom assessment for course-based research experiences

    Get PDF
    Course-based research pedagogy involves positioning students as contributors to authentic research projects as part of an engaging educational experience that promotes their learning and persistence in science. To develop a model for assessing and grading students engaged in this type of learning experience, the assessment aims and practices of a community of experienced course-based research instructors were collected and analyzed. This approach defines four aims of course-based research assessment—(1) Assessing Laboratory Work and Scientific Thinking; (2) Evaluating Mastery of Concepts, Quantitative Thinking and Skills; (3) Appraising Forms of Scientific Communication; and (4) Metacognition of Learning—along with a set of practices for each aim. These aims and practices of assessment were then integrated with previously developed models of course-based research instruction to reveal an assessment program in which instructors provide extensive feedback to support productive student engagement in research while grading those aspects of research that are necessary for the student to succeed. Assessment conducted in this way delicately balances the need to facilitate students’ ongoing research with the requirement of a final grade without undercutting the important aims of a CRE education

    High-detectivity, normal-incidence, mid-infrared (λ ∼ 4 μm)InAs/GaAs(λ∼4μm)InAs/GaAs quantum-dot detector operating at 150 K

    Full text link
    Normal-incidence InAs/GaAs quantum-dot detectors have been grown, fabricated, and characterized for mid-infrared detection in the temperature range from 78 to 150 K. Due to the presence of an Al0.3Ga0.7AsAl0.3Ga0.7As current blocking layer in the heterostructure, the dark current is very low, and at T = 100 K,T=100K, Idark = 1.7 pAIdark=1.7pA for Vbias = 0.1 V.Vbias=0.1V. The peak of the spectral response curve is at λ ∼ 4 μm,λ∼4μm, with Δλ/λ = 0.3Δλ/λ=0.3 and Vbias = 0.1 V.Vbias=0.1V. At T = 100 K,T=100K, for Vbias = 0.3 V,Vbias=0.3V, the peak detectivity, D∗,D∗, is 3×109 cm Hz1/2/W,3×109cmHz1/2/W, and the peak responsivity, Rp,Rp, is 2 mA/W with a photoconductive gain of g = 18.g=18. © 2001 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69931/2/APPLAB-79-3-421-1.pd
    • …
    corecore