4,793 research outputs found

    Infinite average lifetime of an unstable bright state in the green fluorescent protein

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    The time evolution of the fluorescence intensity emitted by well-defined ensembles of Green Fluorescent Proteins has been studied by using a standard confocal microscope. In contrast with previous results obtained in single molecule experiments, the photo-bleaching of the ensemble is well described by a model based on Levy statistics. Moreover, this simple theoretical model allows us to obtain information about the energy-scales involved in the aging process.Comment: 4 pages, 4 figure

    New perturbative solutions of the Kerr-Newman dilatonic black hole field equations

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    This work describes new perturbative solutions to the classical, four-dimensional Kerr--Newman dilaton black hole field equations. Our solutions do not require the black hole to be slowly rotating. The unperturbed solution is taken to be the ordinary Kerr solution, and the perturbation parameter is effectively the square of the charge-to-mass ratio (Q/M)2(Q/M)^2 of the Kerr--Newman black hole. We have uncovered a new, exact conjugation (mirror) symmetry for the theory, which maps the small coupling sector to the strong coupling sector (ϕ→−ϕ\phi \to -\phi). We also calculate the gyromagnetic ratio of the black hole.Comment: Revtex, 27 page

    Racial and Ethnic Disparities in Time to Cure of Incontinence Present at Nursing Home Admission

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    Abstract As many as half of older people that are admitted to nursing homes (NHs) are incontinent of urine and/or feces. Not much is known about the rate of cure of incontinence present at NH admission, but available reports suggest the rate is low. There have been racial and ethnic disparities in incontinence treatment, but the role of disparities in the cure of incontinence is understudied. Using the Peters-Belson method and multilevel predictors, our findings showed that there were disparities in the time to cure of incontinence for Hispanic NH admissions. A significantly smaller proportion of older Hispanic admissions were observed to have their incontinence cured and cured later than expected had they been White non-Hispanic. Reducing disparities in incontinence cure will improve health outcomes of Hispanic NH admissions. Significant predictors in our model suggest strategies to reduce the disparity including attention to managing fecal incontinence and incontinence in those with cognitive impairment, improving residents’ functional status, and increasing resources to NHs admitting older Hispanics with incontinence to develop innovative and cost effective ways to provide equitable quality care

    A statistical exploration of interval-deficient wind speed data for application to wind power assessments

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    Gathering quality wind speed data can be time-consuming and expensive. The present study established whether interval-deficient wind speed data could be rendered useful for wind power assessments. The effect of interval deficiency on the quality of the wind speed data was investigated by studying the behaviour of the Weibull scale and shape factors as the interval size between wind speed measurements increased. Five wind speed data sets obtained from the Southern African Universities Radiometric Network (Sauran) were analysed, based on a proposed procedure to find the true Weibull parameters from an interval-deficient wind speed data set. It was found that the relative errors in the Weibull parameters were, on average, less than 1%, compared with the Weibull parameters computed from a wind speed data set that complies with the IEC 61400-12-1:2005(E) standard. This finding may contribute to time and cost reduction in wind power assessments. It may also promote the application of statistical methods in the renewable energy sector

    Ghost Busting: PT-Symmetric Interpretation of the Lee Model

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    The Lee model was introduced in the 1950s as an elementary quantum field theory in which mass, wave function, and charge renormalization could be carried out exactly. In early studies of this model it was found that there is a critical value of g^2, the square of the renormalized coupling constant, above which g_0^2, the square of the unrenormalized coupling constant, is negative. Thus, for g^2 larger than this critical value, the Hamiltonian of the Lee model becomes non-Hermitian. It was also discovered that in this non-Hermitian regime a new state appears whose norm is negative. This state is called a ghost state. It has always been assumed that in this ghost regime the Lee model is an unacceptable quantum theory because unitarity appears to be violated. However, in this regime while the Hamiltonian is not Hermitian, it does possess PT symmetry. It has recently been discovered that a non-Hermitian Hamiltonian having PT symmetry may define a quantum theory that is unitary. The proof of unitarity requires the construction of a new time-independent operator called C. In terms of C one can define a new inner product with respect to which the norms of the states in the Hilbert space are positive. Furthermore, it has been shown that time evolution in such a theory is unitary. In this paper the C operator for the Lee model in the ghost regime is constructed exactly in the V/N-theta sector. It is then shown that the ghost state has a positive norm and that the Lee model is an acceptable unitary quantum field theory for all values of g^2.Comment: 20 pages, 9 figure

    Klinisch-zeitlicher Verlauf eines solitären retinalen Astrozytoms

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    Zusammenfassung: Retinale Astrozytome sind benigne Tumoren der Netzhaut. Ihr Auftreten kann solitär oder multipel, selten auch bilateral oder als teil eines Syndroms (tuberöse Sklerose, Neurofibromatose Typ I) sein. Am Auge zeigt der Tumor nur eine geringe Wachstumstendenz, weswegen lediglich jährliche Kontrollen ohne Intervention als ausreichend erscheinen. Selten kommt es zu einem aggressiven Wachstum, welches eine Therapie erfordert. Neben der Enukleation des betroffenen Auges gibt es zahlreiche anderen Therapiemöglichkeiten (z.B. vitreoretinale Chirurgie, Brachy- oder Kryotherapie, photodynamische Therapie). Aufgrund des Auftretens retinaler Astrozytome als Teil eines Syndroms sollte die jährliche Kontrolle interdisziplinär erfolge

    Just a Cottage Small (By a Waterfall) / music by James F. Hanley; words by B.G. De Sylva

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    Cover: photo of John McCormack; Publisher: Harms Incorporated (New York)https://egrove.olemiss.edu/sharris_d/1067/thumbnail.jp

    QuNex-An integrative platform for reproducible neuroimaging analytics

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    INTRODUCTION: Neuroimaging technology has experienced explosive growth and transformed the study of neural mechanisms across health and disease. However, given the diversity of sophisticated tools for handling neuroimaging data, the field faces challenges in method integration, particularly across multiple modalities and species. Specifically, researchers often have to rely on siloed approaches which limit reproducibility, with idiosyncratic data organization and limited software interoperability. METHODS: To address these challenges, we have developed Quantitative Neuroimaging Environment & Toolbox (QuNex), a platform for consistent end-to-end processing and analytics. QuNex provides several novel functionalities for neuroimaging analyses, including a turnkey command for the reproducible deployment of custom workflows, from onboarding raw data to generating analytic features. RESULTS: The platform enables interoperable integration of multi-modal, community-developed neuroimaging software through an extension framework with a software development kit (SDK) for seamless integration of community tools. Critically, it supports high-throughput, parallel processing in high-performance compute environments, either locally or in the cloud. Notably, QuNex has successfully processed over 10,000 scans across neuroimaging consortia, including multiple clinical datasets. Moreover, QuNex enables integration of human and non-human workflows DISCUSSION: Collectively, this effort stands to significantly impact neuroimaging method integration across acquisition approaches, pipelines, datasets, computational environments, and species. Building on this platform will enable more rapid, scalable, and reproducible impact of neuroimaging technology across health and disease

    B-mode ultrasound assessment of pupillary function: feasibility, reliability and normal values

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    PURPOSE: To evaluate B-mode ultrasound as a novel method for the examination of pupillary function and to provide normal values for the pupillary reflex as assessed by B-mode ultrasound. METHODS: 100 subjects (49 female, 51 male, mean [range] age 51 [18-80 years]) with no history of ophthalmologic disease, no clinically detectable pupillary defects, and corrected visual acuity >= 0.8 were included in this prospective observational study. B-mode ultrasound was performed with the subjects eyes closed using an Esaote-Mylab25 system according to current guidelines for orbital insonation. A standardized light stimulus was applied. RESULTS: The mean +/- standard deviation left and right pupillary diameters (PD) at rest were 4.7 +/- 0.8 and 4.5 +/- 0.8 mm. Following an ipsilateral light stimulus (Lstim), left and right constricted PD were 2.8 +/- 0.6 and 2.7 +/- 0.6 mm. Following a contralateral Lstim, left and right constricted PD were 2.7 +/- 0.6 and 2.6 +/- 0.5 mm. Left and right pupillary constriction time (PCT) following ipsilateral Lstim were 970 +/- 261.6 and 967 +/- 220 ms. Left and right PCT following a contralateral Lstim were 993.8 +/- 192.6 and 963 +/- 189.4 ms. Patient age was inversely correlated with PD at rest and with PD after ipsilateral and contralateral Lstim (all p<0.001), but not with PCT. CONCLUSIONS: B-mode ultrasound is a simple, rapid and objective method for the quantitative assessment of pupillary function, which may prove useful in a variety of settings where eyelid retraction is impeded or an infrared pupillometry device is unavailable
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