24,963 research outputs found

    Gravitational Thermodynamics of Space-time Foam in One-loop Approximation

    Get PDF
    We show from one-loop quantum gravity and statistical thermodynamics that the thermodynamics of quantum foam in flat space-time and Schwarzschild space-time is exactly the same as that of Hawking-Unruh radiation in thermal equilibrium. This means we show unambiguously that Hawking-Unruh thermal radiation should contain thermal gravitons or the contribution of quantum space-time foam. As a by-product, we give also the quantum gravity correction in one-loop approximation to the classical black hole thermodynamics.Comment: 7 pages, revte

    A blind deconvolution approach to recover effective connectivity brain networks from resting state fMRI data

    Full text link
    A great improvement to the insight on brain function that we can get from fMRI data can come from effective connectivity analysis, in which the flow of information between even remote brain regions is inferred by the parameters of a predictive dynamical model. As opposed to biologically inspired models, some techniques as Granger causality (GC) are purely data-driven and rely on statistical prediction and temporal precedence. While powerful and widely applicable, this approach could suffer from two main limitations when applied to BOLD fMRI data: confounding effect of hemodynamic response function (HRF) and conditioning to a large number of variables in presence of short time series. For task-related fMRI, neural population dynamics can be captured by modeling signal dynamics with explicit exogenous inputs; for resting-state fMRI on the other hand, the absence of explicit inputs makes this task more difficult, unless relying on some specific prior physiological hypothesis. In order to overcome these issues and to allow a more general approach, here we present a simple and novel blind-deconvolution technique for BOLD-fMRI signal. Coming to the second limitation, a fully multivariate conditioning with short and noisy data leads to computational problems due to overfitting. Furthermore, conceptual issues arise in presence of redundancy. We thus apply partial conditioning to a limited subset of variables in the framework of information theory, as recently proposed. Mixing these two improvements we compare the differences between BOLD and deconvolved BOLD level effective networks and draw some conclusions

    A framework of developing a big data platform for construction waste management: a Hong Kong study

    Get PDF
    Big data has shown great potentials in improving management discretion in many areas. The applications of big data in areas such as finance, computer science, health care and medical science have made continued success. Despite of big data’s potentials, its applications in construction waste management (CWM) are still in infant stage. In order to embrace these prospects, this research proposes a platform to apply big data technologies in CWM, by focusing on the CWM status of Hong Kong. This study first presents a framework of the big data platform by describing the data collection, storage and analysis involved in the roadmap of CWM in Hong Kong. The existing unintentionally generated big dataset in CWM in Hong Kong is used to examine the availability of the proposed platform. It was found that this platform could make government, industry and other CWM stakeholders benefit from proper cooperation. Though this study focused on the CWM of Hong Kong, it may act as a driving force to stimulate the adoption of big data in CWM across countries where construction waste is growing as an urgent issue that concerns government, industry, academia, and all the stakeholders.postprin

    How involvement in COVID-19-related work changed nurses' job demands, job resources, and their associations with burnout: Evidence from China

    Get PDF
    China adopted a “Zero-COVID” policy for nearly three years, making Chinese healthcare workers constantly involved in COVID-19-related work. However, little is known about how involvement in COVID-19-related work shaped Chinese nurses’ burnout. This study explores how nurses’ job demands and job resources are associated with their burnout by considering high and low frequent involvements in COVID-19-related work in China. This study employed a cross-sessional design. Guided by Job Demands-Resources (JDR) model, we developed hypotheses and tested them using regression analysis with a sample of 336 nurses working in four public hospitals in Guangdong, China. Overall sample results revealed: 1) frequency of involvement in COVID-19-related work was related to a higher level of workload; 2) nurses’ burnout was positively associated with workload, emotional demands, and work-family conflict, and negatively associated with a relationship with supervisor, remuneration, and independence of work; 3) emotional intelligence mitigated the positive relationship between workload and burnout. Comparison analysis showed significant differences due to the frequency of involvement in COVID-19 work. In the high-frequency group (N = 108), 1) emotional demands were related to a higher level of burnout, and emotional intelligence moderately accentuates the positive relationship between the two variables; 2) remuneration was related to a lower level of burnout; 3) nurses reported higher levels of workload and relationship with the supervisor. In the low-frequency group (N = 147), independence of work was related to a lower level of burnout; We found some evidence that nurses’ job demands and job resources and their associations with burnout differed due to their frequency of involvement in COVID-19-related work. Implications for policy-making and theoretical contribution are discussed.info:eu-repo/semantics/publishedVersio

    Controllable vacuum-induced diffraction of matter-wave superradiance using an all-optical dispersive cavity

    No full text
    Cavity quantum electrodynamics (CQED) has played a central role in demonstrating the fundamental principles of the quantum world, and in particular those of atom-light interactions. Developing fast, dynamical and non-mechanical control over a CQED system is particularly desirable for controlling atomic dynamics and building future quantum networks at high speed. However conventional mirrors do not allow for such flexible and fast controls over their coupling to intracavity atoms mediated by photons. Here we theoretically investigate a novel all-optical CQED system composed of a binary Bose-Einstein condensate (BEC) sandwiched by two atomic ensembles. The highly tunable atomic dispersion of the CQED system enables the medium to act as a versatile, all-optically controlled atomic mirror that can be employed to manipulate the vacuum-induced diffraction of matter-wave superradiance. Our study illustrates a innovative all-optical element of atomtroics and sheds new light on controlling light-matter interactions

    How do anticipated worry and regret predict seasonal influenza vaccination uptake among Chinese adults?

    Get PDF
    Objectives: To test two hypothesized models of how anticipated affect, cognitive risk estimate and vaccination intention might influence vaccination uptake against seasonal influenza. Methods: The study collected baseline and follow-up data during the main influenza seasons (January-March) of 2009 and 2010, respectively, among 507 university students and staff of a university in Hong Kong. Following logistic regression to determine eligible variables, two mediation models of cognitive risk estimate, anticipated affect, vaccination intention and vaccination uptake against seasonal influenza were tested using structural equation modeling. Results: Mediation analyses found that anticipated worry if not vaccinated influenced seasonal influenza vaccination uptake through its effects on either perceived probability of influenza infection (β= 0.45) or intention (.β= 0.45) while anticipated regret if not vaccinated influenced vaccination uptake through its effect on intention (β= 0.45) only; anticipated regret if vaccinated impeded vaccination uptake indirectly through its effect on vaccination intention (β= -0.26) or directly (β= -0.20); perceived probability of influenza infection influenced vaccination uptake through its effect on intention (β= 0.20) or directly (β= 0.22); and finally, intention influenced vaccination uptake directly (β= 0.58). Conclusion: The results suggest that anticipated affect seems to drive risk estimates related to seasonal influenza vaccination rather than vice versa and intention remains an important mediator of the associations of anticipated affect and cognitive risk estimate with vaccination uptake against seasonal influenza. © 2013 Elsevier Ltd.postprin

    Sub and Super-Luminal Propagation of Intense Pulses in Media with Saturated and Reverse Absorption

    Get PDF
    We develop models for the propagation of intense pulses in solid state media which can have either saturated absorption or exhibit reverse absorption . We show that the experiments of Bigelow {\it et al.}[Phys. Rev. Lett. {\bf 90}, 113903 (2003); Science {\bf 301}, 200 (2003).] on subluminal propagation in Ruby and superluminal propagation in Alexandrite are well explained by modelling them as three level and four level systems coupled to Maxwell equations. We present results well beyond the traditional pump-probe approach.Comment: 4 pages, 6 figure

    Beobachtungsstudien im Rahmen eines naturheilkundlichen Klinikverbunds :Teil III: Zwischenergebnisse der diagnosespezifischen Dokumentation Migräne in der Klinik für TraditionelleChinesische Medizin Kötzting

    Get PDF
    Objective: To evaluate the course of symtoms and quality of life of migraine patients after treatment with traditional Chinese medicine. Design: Prospective observational study with 12 months follow-up. Patients: 138 consecutive patients diagnosed by a neurologist to have migraine headaches. Intervention: Complex in-patient treatment with traditional Chinese medicine including acupuncture and Chinese drug therapy. Outcomes: Number of days with headaches per month, number, intensity and duration of migraine attacks, concomitant symptoms, quality of life, global assessment and days off work. Results: The number of days with headaches per month decreased from 9 (median) at baseline to 4 at discharge and was 3 at 12 months. Also, for the other outcomes a clear improvement was seen with a slight wash-out tendency in follow-up. Conclusion: The observed patients with long-lasting migraines had a marked benefit from an in-patient treatment with traditional Chinese medicine
    • …
    corecore