990 research outputs found

    Analysis of the probability of channel satisfactory state in P2P live streaming systems

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    In this paper a model based on user behaviour of P2P live streaming systems was developed in order to analyse one of the key QoS parameter of such systems, i.e. the probability of channel-satisfactory state, the impact of upload bandwidths and channels’ popularity on the probability of channel-satisfactory state was also analysed. Results obtained have shown that channels with high number of patronising peers achieve satisfactory state easily while channels with low number of peers hardly attain satisfactory state. This called for the need to design a framework or incentive scheme for effective functionality of P2P live streaming systems which will favour all channels regardless of their popularities.Keywords: P2P Systems, QoS Parameters, Satisfactory State, Video Streaming, Fluid Mod

    On Classifying Sepsis Heterogeneity in the ICU: Insight Using Machine Learning

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    Current machine learning models aiming to predict sepsis from Electronic Health Records (EHR) do not account for the heterogeneity of the condition, despite its emerging importance in prognosis and treatment. This work demonstrates the added value of stratifying the types of organ dysfunction observed in patients who develop sepsis in the ICU in improving the ability to recognise patients at risk of sepsis from their EHR data. Using an ICU dataset of 13,728 records, we identify clinically significant sepsis subpopulations with distinct organ dysfunction patterns. Classification experiments using Random Forest, Gradient Boost Trees and Support Vector Machines, aiming to distinguish patients who develop sepsis in the ICU from those who do not, show that features selected using sepsis subpopulations as background knowledge yield a superior performance regardless of the classification model used. Our findings can steer machine learning efforts towards more personalised models for complex conditions including sepsis.Comment: 3 Figures and 2 tables. Accepted for publication at the Journal of American Medical Informatics Associatio

    Mode oscillation and harmonic distortions associated with sinusoidal modulation of semiconductor lasers

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    This paper investigates mode dynamics, operation characteristics and signal distortions associated with sinusoidal modulation of semiconductor lasers. The study is based on intensive integrations of the multimode rate equation model of semiconductor lasers over wide ranges of the modulation frequency and depth. The rate equations take into account both spectral symmetric and asymmetric suppressions of modal gain. The higher harmonic distortions as well as the half harmonic distortion associated with the period doubling effect are investigated. The study is applied to both cases of single-mode and multimode oscillations of the non-modulated laser. The obtained results showed that the modulated signal has six distinct waveforms depending on the modulation conditions; three types have continuous periodic waveforms and the others have periodic pulsing waveforms. The modulated laser is found to oscillate in a single mode under weak modulation where the modulated signal is continuous, whereas the pulsing signals are associated with multimode oscillation. The higher harmonic distortions of single-mode laser are lower than those of two-mode lasers, and become serious at modulation frequencies around the relaxation oscillation frequency. These distortions are highest when the laser output is pulsating and the pulses are superposed by relaxation oscillations. © EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2012

    Finite Element Analysis of Stress-Strain Response at the Tool Pin During Friction Stir Process

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    AbstractFriction stir welding (FSW) is a relatively new solid-state joining process which is considered energy efficient, eco-friendly and versatile. High stress and strain occur at the rotating tool, consisting of a pin (probe) and a shoulder, during the friction stir process. The geometrical design of the tool has some impact in terms of stress and strain once static load is applied against the tool. In this work, specific stress can be found on the tool due to the plunging and travel process that is analysed using finite element method. In the present work, a steady state finite element stress analysis of friction stir welding was carried out using CATIA V5 software. The critical points of the FSW tool are located mainly on the edge between the shoulder and the pin, where a large amount of stress is found and further leads to failure or tool defects. This critical stress and strain can be reduced by enlarging the diameter size of the pin and increasing tool life

    The impact of external pressure and sustainable management practices on manufacturing performance and environmental outcomes

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    Purpose: The study investigates the direct effect of external pressure on environmental outcomes and manufacturing performance and examines the mediating effect of sustainable management practice. Design/methodology/approach: This study draws upon Institutional Theory and Resource Based View to understand how factors such as external pressure and sustainable management relate with environmental outcomes and manufacturing performance. The model specifies previously unexplored direct and mediating relationships between external pressure, sustainable management, environmental outcomes and manufacturing performance. The empirical analysis is based on data collected from the sixth edition of the International Manufacturing Strategy Survey (IMSS). The research hypotheses were tested using Structural Equation Modelling. Findings: Results show that while there is a significant direct and mediating relationship between external pressure, adoption of formal sustainability programs and environmental outcomes, such significant relationships do not exist with manufacturing performance. Practical implications: The study shows that external pressure can influence the adoption of sustainable practices but the adoption of formal sustainable practices does not necessarily lead to an improvement in manufacturing performance. The implication therefore is that managers need to clearly understand what the actual benefits of sustainability are and where financial advantage, other than manufacturing cost, may be gained. Originality/value: The relationship between the adoption of sustainable practices and organisational performance is a complex one. In contrast to previous studies, this study found that while external pressure and sustainable management relate positively with environmental outcomes, no such relationship exists with manufacturing performance. This raises a number of questions over naively following such strategies

    Prieurianin Causes Weight Loss in Diet-Induced Obese Mice and Inhibits Adipogenesis in Cultured Preadipocytes

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    The global increase in the incidence of obesity has emerged as one of the most serious public health risks in recent years. Despite the enormity of the obesity pandemic, there are currently only two FDA-approved therapies for its treatment and these drugs exhibit modest effi cacy and have limiting side effects. Prieurianin is a plant limonoid product that deters feeding in insect larvae. We investigated in this study the effects of prieurianin on weight loss and adipogenesis. Our results showed that prieurianin causes weight loss by reducing energy intake in obese mice on highcalorie diet. We also found that prieurianin is anti-adipogenic in cultured preadipocytes and adipocytes by inhibiting proliferation and differentiation of preadipocytes into adipocytes, and induces either dedifferentiation or delipidation of mature adipocytes. Whether prieurianin can potentially be used for obesity treatment in human warrants further investigation

    On the second parameter of an (m,p)(m, p)-isometry

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    A bounded linear operator TT on a Banach space XX is called an (m,p)(m, p)-isometry if it satisfies the equation \sum_{k=0}^{m}(-1)^{k} {m \choose k}\|T^{k}x\|^{p} = 0,forall, for all x \in X.Inthispaperwestudythestructurewhichunderliesthesecondparameterof. In this paper we study the structure which underlies the second parameter of (m, p)isometricoperators.Weconcentrateondeterminingwhenan-isometric operators. We concentrate on determining when an (m, p)isometryisa-isometry is a (\mu, q)isometryforsomepair(-isometry for some pair (\mu, q).Wealsoextendthedefinitionof. We also extend the definition of (m, p)isometry,toinclude-isometry, to include p=\inftyandstudybasicpropertiesofthese and study basic properties of these (m, \infty)$-isometries

    Health-related quality-of-life results from the randomised phase II TAVAREC trial on temozolomide with or without bevacizumab in 1p/19q intact first-recurrence World Health Organization grade 2 and 3 glioma (European Organization for Research and Treatment of Cancer 26091)

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    Background: In an international randomised controlled phase II study of temozolomide (TMZ) versus TMZ in combination with bevacizumab (BEV) in locally diagnosed non-1p/19q co-deleted World Health Organization grade 2 or 3 gliomas with a first and contrast-enhancing recurrence after initial radiotherapy, and overall survival at 12 months was not significantly different (61% in the TMZ arm and 55% in the TMZ + BEV arm). Objectives: Health-related quality of life (HRQoL) was a key secondary end-point in this trial, and the main objective of this study was to determine the impact of the addition of BEV to TMZ on HRQoL. Methods: HRQoL was assessed using the European Organization for Research and Treatment of Cancer QLQ-C30 (version 3) and QLQ-BN20 at baseline, and then every 12 weeks until disease progression. The pre-selected primary HRQoL end-point was the QLQ-C30 global health scale, with self-perceived cognitive functioning and pain selected as secondary HRQoL issues. Analysis was undertaken using linear mixed modelling and complemented with sensitivity analyses using summary statistics. A difference was considered clinically relevant with ≥10 points difference on a 100-point scale. Results: Baseline compliance was high at 94% and remained above 60% until 72 weeks, limiting the analysis to 60 weeks. Compliance was similar in both arms. We found no statistically significant or clinically significant differences between the primary HRQoL end-point in both treatment arms (p = 0.2642). The sensitivity analyses confirmed this finding. The overall test for post-baseline differences between the two treatment arms also showed no statistically or clinically significant differences regarding the selected secondary end-point scales. Interpretation: The addition of BEV to TMZ in this patient group neither improves nor negatively impacts HRQoL.</p

    Automatic Detector of Abnormal EEG for Preterm Infants

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    Many of preterm babies suffer from neural disorders caused by birth complications. Hence, early prediction of neural disorders, in preterm infants, is extremely crucial for neuroprotective intervention. In this scope, the goal of this research was to propose an automatic way to study preterm babies Electroencephalograms (EEG). EEG were preprocessed and a time series of standard deviation was computed. These series were thresholded to detect Inter Burst Intervals (IBI). Features were extracted from bursts and IBI and were then classified as Abnormal or Normal using a Multiple Linear Regression. The method was successfully validated on a corpus of 100 infants with no early indication of brain injury. It was also implemented with a user-friendly interface using Java

    Combustion of fuel blends containing digestate pyrolysis oil in a multi-cylinder compression ignition engine

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    Digestate from the anaerobic digestion conversion process is widely used as a farm land fertiliser. This study proposes an alternative use as a source of energy. Dried digestate was pyrolysed and the resulting oil was blended with waste cooking oil and butanol (10, 20 and 30 vol.%). The physical and chemical properties of the pyrolysis oil blends were measured and compared with pure fossil diesel and waste cooking oil. The blends were tested in a multi-cylinder indirect injection compression ignition engine.Engine combustion, exhaust gas emissions and performance parameters were measured and compared with pure fossil diesel operation. The ASTM copper corrosion values for 20% and 30% pyrolysis blends were 2c, compared to 1b for fossil diesel. The kinematic viscosities of the blends at 40 C were 5–7 times higher than that of fossil diesel. Digested pyrolysis oil blends produced lower in-cylinder peak pressures than fossil diesel and waste cooking oil operation. The maximum heat release rates of the blends were approximately 8% higher than with fossil diesel. The ignition delay periods of the blends were higher; pyrolysis oil blends started to combust late and once combustion started burnt quicker than fossil diesel. The total burning duration of the 20% and 30% blends were decreased by 12% and 3% compared to fossil diesel. At full engine load, the brake thermal efficiencies of the blends were decreased by about 3–7% when compared to fossil diesel. The pyrolysis blends gave lower smoke levels; at full engine load, smoke level of the 20% blend was 44% lower than fossil diesel. In comparison to fossil diesel and at full load, the brake specific fuel consumption (wt.) of the 30% and 20% blends were approximately 32% and 15% higher. At full engine load, the CO emission of the 20% and 30% blends were decreased by 39% and 66% with respect to the fossil diesel. Blends CO2 emissions were similar to that of fossil diesel; at full engine load, 30% blend produced approximately 5% higher CO2 emission than fossil diesel. The study concludes that on the basis of short term engine experiment up to 30% blend of pyrolysis oil from digestate of arable crops can be used in a compression ignition engine
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