4,762 research outputs found

    Transient dynamics of nonlinear magneto-optical rotation

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    We analyze nonlinear magneto-optical rotation (NMOR) in rubidium vapor subjected to continuously-scanned magnetic field. By varying magnetic-field sweep rate, a transition from traditionally-observed dispersive-like NMOR signals (low sweep rate) to oscillating signals (higher sweep rates) is demonstrated. The transient oscillatory behavior is studied versus light and magnetic-field parameters, revealing a strong dependence of the signals on magnetic-sweep rate and light intensity. The experimental results are supported with density-matrix calculations, which enable quantitative analysis of the effect. Fitting of the signals simulated versus different parameters with a theoretically-motivated curve reveals presence of oscillatory and static components in the signals. The components depend differently on the system parameters, which suggests their distinct nature. The investigations provide insight into dynamics of ground-state coherence generation and enable application of NMOR in detection of transient spin couplings.Comment: 9 pages, 7 figures, Submitted to Physical Review

    Receding horizon filtering for a class of discrete time-varying nonlinear systems with multiple missing measurements

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    This paper is concerned with the receding horizon filtering problem for a class of discrete time-varying nonlinear systems with multiple missing measurements. The phenomenon of missing measurements occurs in a random way and the missing probability is governed by a set of stochastic variables obeying the given Bernoulli distribution. By exploiting the projection theory combined with stochastic analysis techniques, a Kalman-type receding horizon filter is put forward to facilitate the online applications. Furthermore, by utilizing the conditional expectation, a novel estimation scheme of state covariance matrices is proposed to guarantee the implementation of the filtering algorithm. Finally, a simulation example is provided to illustrate the effectiveness of the established filtering scheme.This work was supported in part by the Deanship of Scientific Research (DSR) at King Abdulaziz University in Saudi Arabia [grant number 16-135-35-HiCi], the National Natural Science Foundation of China [grant number 61329301], [grant number 61203139], [grant number 61134009], and [grant number 61104125], Royal Society of the U.K., the Shanghai Rising-Star Program of China [grant number 13QA1400100], the Shu Guang project of Shanghai Municipal Education Commission and Shanghai Education Development Foundation [grant number 13SG34], the Fundamental Research Funds for the Central Universities, DHU Distinguished Young Professor Program, and the Alexander von Humboldt Foundation of Germany

    Research on mechanisms of alloy strengthening. Part 1 - Strengthening through fine particle dispersion. Part 2 - Control of structure and properties by means of rapid quenching of liquid metals /splat cooling/ Semiannual report

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    Alloy strengthening mechanisms - strengthening by fine particle dispersion, and structure and properties control by rapid quenching or splat cooling of liquid metal

    Long-Term Stability of an Area-Reversible Atom-Interferometer Sagnac Gyroscope

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    We report on a study of the long-term stability and absolute accuracy of an atom interferometer gyroscope. This study included the implementation of an electro-optical technique to reverse the vector area of the interferometer for reduced systematics and a careful study of systematic phase shifts. Our data strongly suggests that drifts less than 96 μ\mudeg/hr are possible after empirically removing shifts due to measured changes in temperature, laser intensity, and several other experimental parameters.Comment: 4 pages, 4 figures, submitted to PR

    Unveiling What is Written in The Stars: Analyzing Explicit, Implicit, and Discourse Patterns of Sentiment in Social Media

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    Deciphering consumers' sentiment expressions from big data (e.g., online reviews) has become a managerial priority to monitor product and service evaluations. However, sentiment analysis, the process of automatically distilling sentiment from text, provides little insight regarding the language granularities beyond the use of positive and negative words. Drawing on speech act theory, this study provides a fine-grained analysis of the implicit and explicit language used by consumers to express sentiment in text. An empirical text-mining study using more than 45,000 consumer reviews demonstrates the differential impacts of activation levels (e.g., tentative language), implicit sentiment expressions (e.g., commissive language), and discourse patterns (e.g., incoherence) on overall consumer sentiment (i.e., star ratings). In two follow-up studies, we demonstrate that these speech act features also influence the readers' behavior and are generalizable to other social media contexts, such as Twitter and Facebook. We contribute to research on consumer sentiment analysis by offering a more nuanced understanding of consumer sentiments and their implications

    The emotional review–reward effect: how do reviews increase impulsivity?

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    A growing reliance on customer reviews prompts firms to develop strategies to encourage customers to post online reviews of their products. However, little research investigates the behavioral consequences of writing a review. The act of sharing personal opinions through reviews is a rewarding experience and makes customers feel socially connected. With an application of reverse alliesthesia theory, the current study predicts that such rewarding experiences drive online reviewers to seek other rewards, such as impulsive buying. Three lab-based and two field studies demonstrate such an emotional review–reward effect: sharing emotional inf ormation in the public realm of customer reviews, rather than forming similar opinions privately, drives participants to make more impulsive buying decisions

    Sector Retinitis Pigmentosa: Extending the Molecular Genetics Basis and Elucidating the Natural History

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    PURPOSE: To determine the genetic background of sector retinitis pigmentosa (RP), natural history, in order to better inform patient counselling. DESIGN: Retrospective case series. METHODS: Review of clinical notes, retinal imaging including color fundus photography (CFP), fundus autofluorescence (FAF), and optical coherence tomography (OCT), electrophysiological assessment (ERG), and molecular genetic testing was performed in patients with sector RP from a single tertiary referral center. MAIN OUTCOME: Measures: Reporting demographic data, signs and symptoms, visual acuity, molecular genetics, ERG, FAF and OCT findings. RESULTS: Twenty-six molecularly confirmed patients from 23 different families were identified, harboring likely disease-causing variants in nine genes. The mode of inheritance was autosomal recessive (AR, n=6: USH1C, n=2; MYO7A, n=2; CDH3, n=1; EYS, n=1), X-linked (XL, n=4: PRPS1, n=1; RPGR, n=3), and autosomal dominant (AD, n=16: IMPDH1, n=3; RP1, n=3; RHO, n=10), with a mean age of disease onset of 38.5, 30.5 and 39.0 years respectively. Five of these genes have not previously been reported to cause sector RP (PRPS1, MYO7A, EYS, IMPDH1, and RP1). Inferior and nasal predilection was common across the different genotypes and patients tended to maintain good central vision. Progression on serial FAF was observed in RPGR, MYO7A, CDH23, EYS, IMPDH1, RP1 and RHO-associated sector RP. CONCLUSIONS: The genotypic spectrum of the disease is broader than previously reported. The provided longitudinal data will help to provide more accurate patient prognosis and counselling, as well as inform patients' potential participation in the increasing numbers of trials of novel therapeutics and access to future treatments

    Endometrial stromal cells of women with recurrent miscarriage fail to discriminate between high- and low-quality human embryos

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    Background The aetiology of recurrent miscarriage (RM) remains largely unexplained. Women with RM have a shorter time to pregnancy interval than normally fertile women, which may be due to more frequent implantation of non-viable embryos. We hypothesized that human endometrial stromal cells (H-EnSCs) of women with RM discriminate less effectively between high-and low-quality human embryos and migrate more readily towards trophoblast spheroids than H-EnSCs of normally fertile women. Methodology/Principal Findings Monolayers of decidualized H-EnSCs were generated from endometrial biopsies of 6 women with RM and 6 fertile controls. Cell-free migration zones were created and the effect of the presence of a high-quality (day 5 blastocyst, n = 13), a low-quality (day 5 blastocyst with three pronuclei or underdeveloped embryo, n = 12) or AC-1M88 trophoblast cell line spheroid on H-ESC migratory activity was analyzed after 18 hours. In the absence of a spheroid or embryo, migration of H-EnSCs from fertile or RM women was similar. In the presence of a low-quality embryo in the zone, the migration of H-EnSCs of control women was inhibited compared to the basal migration in the absence of an embryo (P<0.05) and compared to the migration in the presence of high-quality embryo (p<0.01). Interestingly, the migratory response H-EnSCs of women with RM did not differ between high- and low-quality embryos. Furthermore, in the presence of a spheroid their migration was enhanced compared to the H-EnSCs of controls (p<0.001). Conclusions H-EnSCs of fertile women discriminate between high- and low-quality embryos whereas H-EnSCs of women with RM fail to do so. H-EnSCs of RM women have a higher migratory response to trophoblast spheroids. Future studies will focus on the mechanisms by which low-quality embryos inhibit the migration of H-EnSCs and how this is deregulated in women with RM
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