3,611 research outputs found
Transient dynamics of nonlinear magneto-optical rotation
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
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
Unveiling What is Written in The Stars: Analyzing Explicit, Implicit, and Discourse Patterns of Sentiment in Social Media
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?
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
Endometrial stromal cells of women with recurrent miscarriage fail to discriminate between high- and low-quality human embryos
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
Cutting through Content Clutter: How Speech and Image Acts Drive Consumer Sharing of Social Media Brand Messages
Consumer-to-consumer brand message sharing is pivotal for effective social media marketing. Even as companies join social media conversations and generate millions of brand messages, it remains unclear what, how, and when brand messages stand out and prompt sharing by consumers. With a conceptual extension of speech act theory, this study offers a granular assessment of brands’ message intentions (i.e., assertive, expressive, or directive) and the effects on consumer sharing. A text mining study of more than two years of Facebook posts and Twitter tweets by well-known consumer brands empirically demonstrates the impacts of distinct message intentions on consumers’ message sharing. Specifically, the use of rhetorical styles (alliteration and repetitions) and cross-message compositions enhance consumer message sharing. As a further extension, an image-based study demonstrates that the presence of visuals, or so-called image acts, increases the ability to account for message sharing. The findings explicate brand message sharing by consumers and thus offer guidance to content managers for developing more effective conversational strategies in social media marketing
Long-Term Stability of an Area-Reversible Atom-Interferometer Sagnac Gyroscope
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 deg/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
RNA interference machinery regulates chromosome dynamics during mitosis and meiosis in fission yeast
The regulation of higher-order chromosome structure is central to cell division and sexual reproduction. Heterochromatin assembly at the centromeres facilitates both kinetochore formation and sister chromatid cohesion, and the formation of specialized chromatin structures at telomeres serves to maintain the length of telomeric repeats, to suppress recombination, and to aid in formation of a bouquet-like structure that facilitates homologous chromosome pairing during meiosis. In fission yeast, genes encoding the Argonaute, Dicer, and RNA-dependent RNA polymerase factors involved in RNA interference (RNAi) are required for heterochromatin formation at the centromeres and mating type region. In this study, we examine the effects of deletions of the fission yeast RNAi machinery on chromosome dynamics during mitosis and meiosis. We find that the RNAi machinery is required for the accurate segregation of chromosomes. Defects in mitotic chromosome segregation are correlated with loss of cohesin at centromeres. Although the telomeres of RNAi mutants maintain silencing, length, and localization of the heterochromatin protein Swi6, we discovered defects in the proper clustering of telomeres in interphase mitotic cells. Furthermore, a small proportion of RNAi mutant cells display aberrant telomere clustering during meiotic prophase. This study demonstrates that the fission yeast RNAi machinery is required for the proper regulation of chromosome architecture during mitosis and meiosis
Unravelling the impact of soil types on zinc, iron, and selenium concentrations in grains and straw of wheat/Amblyopyrum muticum and wheat/Triticum urartu doubled haploid lines
The concentration of mineral nutrients in plants is associated with bioavailabilities of soil mineral nutrients, which are regulated by various soil physio-chemical properties. A pot experiment was conducted to investigate the effects of soil type on grain and straw zinc (Zn), iron (Fe) and selenium (Se) concentrations of wheat/Amblyopyrum muticum and wheat/Triticum urartu doubled haploid lines. A set of 42 treatments in a factorial combination with 21 genotypes and two soil types collected from Ngabu and Chitedze Research Stations in Malawi was laid in a randomised complete block design (RCBD) in three replicates. Pre-experiment soil Zn and Fe were extracted using DTPA extraction method followed by analysis with inductively coupled plasma-mass spectrometry (ICP-MS). Aqua-regia hotplate acid digestion was used to extract soil Se and analysis was done using ICPM-MS. Grain and straw samples were digested using nitric acid digestion (HNO3) and analysed using ICP-MS. Soil analysis results showed that the two soils had the same textural class (Sandy clay loam), but different mineral concentrations, pH levels and percentage organic matter. Analysis of variance revealed a ~two-fold higher Zn concentration in grains grown in low pH, high Zn soils (Chitedze soils) compared to grains grown in high pH, low Zn soils (Ngabu soils). Variation in grain Zn concentration was associated with the genotypes (p = 0002), soil type (p = <0.0001), and their interaction (p = 0.035). Grain Fe was 1.3-fold higher in low pH than in high pH soils, and it was influenced by genotypes (p = < 0.0001) and soil type (p = <0.0001). Grain Se was highly associated with soil type (p = <0.0001), and it was 30-fold higher in high pH than in low pH soils. Straw Zn was generally higher in plants grown in Chitedze soils than Ngabu soils, whilst straw Se was higher in plants grown in Ngabu soils than Chitedze soils. The findings demonstrate the significance of soil physio-chemical properties for mineral accumulation and distribution to plant parts, thus informing future breeding programs on importantconsiderations on crop genetic biofortification with the three mineral element
BCG vaccination status may predict sputum conversion in patients with pulmonary tuberculosis:a new consideration for an old vaccine?
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