598 research outputs found

    Higher-order Petri net models based on artificial neural networks

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    AbstractIn this paper, the properties of higher-order neural networks are exploited in a new class of Petri nets, called higher-order Petri nets (HOPN). Using the similarities between neural networks and Petri nets this paper demonstrates how the McCullock-Pitts models and the higher-order neural networks can be represented by Petri nets. A 5-tuple HOPN is defined, a theorem on the relationship between the potential firability of the goal transition and the T-invariant (HOPN) is proved and discussed. The proposed HOPN can be applied to the polynomial clause subset of first-order predicate logic. A five-clause polynomial logic program example is also included to illustrate the theoretical results

    Bayesian Semi-parametric Expected Shortfall Forecasting in Financial Markets

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    Bayesian semi-parametric estimation has proven effective for quantile estimation in general and specifically in financial Value at Risk forecasting. Expected short-fall is a competing tail risk measure, involving a conditional expectation beyond a quantile, that has recently been semi-parametrically estimated via asymmetric least squares and so-called expectiles. An asymmetric Gaussian density is proposed allowing a likelihood to be developed that leads to Bayesian semi-parametric estimation and forecasts of expectiles and expected shortfall. Further, the conditional autoregressive expectile class of model is generalised to two fully nonlinear families. Adaptive Markov chain Monte Carlo sampling schemes are employed for estimation in these families. The proposed models are clearly favoured in an empirical study forecasting eleven financial return series: clear evidence of more accurate expected shortfall forecasting, compared to a range of competing methods is found. Further, the most favoured models are those estimated by Bayesian methods

    An introduction to crowdsourcing for language and multimedia technology research

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    Language and multimedia technology research often relies on large manually constructed datasets for training or evaluation of algorithms and systems. Constructing these datasets is often expensive with significant challenges in terms of recruitment of personnel to carry out the work. Crowdsourcing methods using scalable pools of workers available on-demand offers a flexible means of rapid low-cost construction of many of these datasets to support existing research requirements and potentially promote new research initiatives that would otherwise not be possible

    The incidence of all-cause, cardiovascular and respiratory disease admission among 20,252 users of lisinopril vs. perindopril: a cohort study

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    Background: Major international guidelines do not offer explicit recommendations on any specific angiotensin-converting enzyme inhibitor (ACEI) agent over another within the same drug group. This study compared the effectiveness of lisinopril vs. perindopril in reducing the incidence of hospital admission due to all-cause, cardiovascular disease and respiratory disease. Methods: Adult patients who received new prescriptions of lisinopril or perindopril from 2001 to 2005 in all public hospitals and clinics in Hong Kong were included, and followed up for ≥2 years. The incidence of admissions due to all-cause, cardiovascular disease and respiratory disease were evaluated, respectively, by using Cox proportional hazard regression models. The regression models were constructed with propensity score matching to minimize indication biases. Results: A total of 20,252 eligible patients with an average age of 64.5 years (standard deviation 15.0) were included. The admission rate at 24 months within the date of index prescription due to any cause, cardiovascular disease and respiratory disease among lisinopril vs. perindopril users was 24.8% vs. 24.8%, 13.7% vs. 14.0% and 6.9% vs. 6.3%, respectively. Lisinopril users were significantly more likely to be admitted due to respiratory diseases (adjusted hazard ratios [AHR] = 1.25, 95% CI 1.08 to 1.43, p = 0.002 at 12 months; AHR = 1.17, 95% CI 1.04 to 1.31, p = 0.009 at 24 months) and all causes (AHR = 1.12, 95% CI 1.05 to 1.19, p < 0.001 at 24 months) than perindopril users. Conclusions: These findings support intra-class differences in the effectiveness of ACEIs, which could be considered by clinical guidelines when the preferred first-line antihypertensive drugs are recommended

    Association between statins and the risk of suicide attempt, depression, anxiety, and seizure: A population-based, self-controlled case series study

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    Background: Risk of suicide attempt, depression, anxiety and seizure and the association with statins is an ongoing debate. We aim to investigate the association between statins and the above neuropsychological outcomes, in specific pre- and post-exposure time windows./ Methods: We identified patients aged 40–75 years old who were dispensed a statin between January 1, 2003 and December 31, 2012 from the Hong Kong Clinical Data Analysis & Reporting System (CDARS), an electronic medical records database. Patients with new onset of suicide attempt, depression, anxiety and seizure were derived from the original dataset separately, in a self-controlled case series study design. A non-parametric spline-based self-controlled case series model was built to measure continuous changes of risk./ Results: We identified 396,614 statin users. The risk of each outcome was elevated prior to statin initiation with incidence rate ratios of 1.38 (95 % CI, 1.09–1.74) for suicide attempt, 1.29 (95 % CI, 1.15–1.45) for depression, 1.35 (95 % CI, 1.19–1.53) for anxiety, and 1.45 (95 % CI, 1.21–1.73) for seizure. The incidence rate ratios remained elevated after the initiation of statins during the first 90 and 91–365 days after statin prescription and decreased to the baseline level after 1 year of continuous prescription./ Limitations: CDARS includes prescription data but not adherence data, which could lead to misclassification of exposure periods./ Conclusions: Our study does not support a direct association between statin use and suicide attempt, depression, anxiety and seizure, whose risks could be explained by cardiovascular events, for which statins were prescribed

    SARS Coronavirus Detection Methods

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    Using clinical samples from patients with severe acute respiratory syndrome, we showed that the sensitivities of a quantitative reverse transcription–polymerase chain reaction (80% for fecal samples and 25% for urine samples) were higher than those of the polyclonal (50% and 5%) and monoclonal (35% and 8%) antibody-based nucleocapsid antigen capture enzyme-linked immunosorbent assays

    Charged Higgs bosons in the Next-to MSSM (NMSSM)

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    The charged Higgs boson decays H±W±A1H^\pm\to W^\pm A_1 and H±W±hiH^\pm\to W^\pm h_i are studied in the framework of the next-to Minimal Supersymmetric Standard Model (NMSSM). It is found that the decay rate for H±W±A1H^\pm\to W^\pm A_1 can exceed the rates for the τ±ν\tau^\pm\nu and tbtb channels both below and above the top-bottom threshold. The dominance of H±W±A1H^\pm\to W^\pm A_1 is most readily achieved when A1A_1 has a large doublet component and small mass. We also study the production process ppH±A1pp\to H^\pm A_1 at the LHC followed by the decay H±W±A1H^\pm\to W^\pm A_1 which leads to the signature W±A1A1W^\pm A_1 A_1. We suggest that ppH±A1p p\to H^\pm A_1 is a promising discovery channel for a light charged Higgs boson in the NMSSM with small or moderate tanβ\tan\beta and dominant decay mode H±W±A1H^\pm \to W^\pm A_1. This W±A1A1W^\pm A_1 A_1 signature can also arise from the Higgsstrahlung process ppW±h1pp\to W^\pm h_1 followed by the decay h1A1A1h_1\to A_1 A_1. It is shown that there exist regions of parameter space where these processes can have comparable cross sections and we suggest that their respective signals can be distinguished at the LHC by using appropriate reconstruction methods.Comment: 20 pages, 22 eps figures, more reference adde

    Quantum computing implementations with neutral particles

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    We review quantum information processing with cold neutral particles, that is, atoms or polar molecules. First, we analyze the best suited degrees of freedom of these particles for storing quantum information, and then we discuss both single- and two-qubit gate implementations. We focus our discussion mainly on collisional quantum gates, which are best suited for atom-chip-like devices, as well as on gate proposals conceived for optical lattices. Additionally, we analyze schemes both for cold atoms confined in optical cavities and hybrid approaches to entanglement generation, and we show how optimal control theory might be a powerful tool to enhance the speed up of the gate operations as well as to achieve high fidelities required for fault tolerant quantum computation.Comment: 19 pages, 12 figures; From the issue entitled "Special Issue on Neutral Particles

    Mn clusterisation in Ga1-xMnxN

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    Local structure of Mn atoms in Ga1-xMnxN has been investigated by the Mn L3 edge x-ray absorption spectrum (XAS) at total electron yield mode, which preferentially looks at atoms near the surface. A modeling defects configuration, the Mn5 micro-clusters complexed with substitutional MnGa and interstitial MnI is found for the higher Mn doping concentration. This new configuration is also confirmed by the total energy calculations.Comment: 17 pages, 5 figures, to be published in Solid. State Commu

    New Lymphogranuloma Venereum Chlamydia trachomatis Variant, Amsterdam

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    We retrospectively conducted a study of men who have sex with men who visited the Amsterdam, the Netherlands, sexually transmitted diseases clinic from January 2002 to December 2003 and had rectal Chlamydia trachomatis infections. We found that symptomatic (73%) as well as asymptomatic (43%) patients were infected with a new C. trachomatis LGV variant
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