1,687 research outputs found

    The Greek language of the diaspora in the era of globalisation

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    This paper is divided into two parts. The first one deals with the Greek language and education in the United States, focusing on schools, books, teachers and the educational policy of the Greek Orthodox Archdiocese and the Greek Government regarding this subject. For comparative purposes a brief portion of this section deals with the teaching of the Greek language and culture in Canada, Australia, Germany, and other countries. The second part focuses on the global aspects of the Greek language. It discusses the effects of the fall of Communism and the full membership of Greece in the EU and how these factors affected the Greek language and Government policy, regarding the funding of Greek Education globally. Finally, the paper offers some recommendations for maximising the benefits arising from this new world of globalisation

    Analytical modelling of congestion for 6LoWPAN networks

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    The IPv6 over Low-Power Wireless Personal Area Network (6LoWPAN) protocol stack is a key part of the Internet of Things (IoT) where the 6LoWPAN motes will account for the majority of the IoT ‘things’. In 6LoWPAN networks, heavy network traffic causes congestion which significantly affects the overall performance and the quality of service metrics. In this paper, a new analytical model of congestion for 6LoWPAN networks is proposed using Markov chain and queuing theory. The derived model calculates the buffer loss probability and the channel loss probability as well as the number of received packets at the final destination in the presence of congestion. Also, we calculate the actual wireless channel capacity of IEEE 802.15.4 with and without collisions based on Contiki OS implementation. The validation of the proposed model is performed with different scenarios through simulation by using Contiki OS and Cooja simulator. Simulation results show that the analytical modelling of congestion has an accurate agreement with simulation

    Transfers to psychiatry through the consultation-liaison psychiatry service: 11 years of experience

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    BACKGROUND: There are only a few reports on issues related to patient transfer from medical and surgical departments to the psychiatric ward by the consultation-liaison psychiatry service, although it is a common practice. Here, we present a study assessing the factors that influence such transfers. METHOD: We examined the demographic and clinical backgrounds of a group of patients transferred from internal medicine and surgery to the psychiatric ward over an 11-year period. A comparison was made of this data with data obtained from a group of non-transferred patients, also seen by the same consultation-liaison psychiatry service. RESULTS: According to our findings, the typical transferred patient, either female or male, is single, divorced or widowed, lives alone, belongs to a lower socioeconomic class, presents initially with (on the whole) a disturbed and disruptive behaviour, has had a recent suicide attempt with persistent suicidal ideas, suffers from a mood disorder (mainly depressive and dysthymic disorders), has a prior psychiatric history as well as a prior psychiatric inpatient treatment, and a positive diagnosis on axis II of the five axis system used for mental health diagnosis. CONCLUSION: The transfer of a patient to the psychiatric ward is a decision depending on multiple factors. Medical diagnoses do not seem to play a major role in the transfer to the psychiatric ward. From the psychiatric diagnosis, depressive and dysthymic disorders are the most common in the transferred population, whilst the transfer is influenced by social factors regarding the patient, the patient's behaviour, the conditions in the ward she/he is treated in and any recent occurrence(s) that increase the anxiety of the staff

    Metabonomic Investigation of Liver Profiles of Nonpolar Metabolites Obtained from Alcohol-Dosed Rats and Mice Using High Mass Accuracy MSn Analysis

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    Alcoholism is a complex disorder that, in man, appears to be genetically influenced, although the underlying genes and molecular pathways are not completely known. Here the intragastric alcohol feeding model in rodents was used together with high mass accuracy LC/MS(n) analysis to assess the metabonomic changes in nonpolar metabolite profiles for livers from control and alcohol treated rats and mice. Ion signals with a peak area variance of less than 30% (based on repeat analysis of a pooled quality control sample analysed throughout the batch) were submitted to multivariate statistical analysis (using principal components analysis, PCA). PCA revealed robust differences between profiles from control and alcohol-treated animals from both species. The major metabolites seen to differ between control and alcohol-treated animals were identified using high accuracy MS(n) data and verified using external search engines (http://www.lipidmaps.org; http://www.hmdb.ca; http://www.genome.jp/kegg/) and authentic standards. The main metabolite classes to show major changes in the alcoholic liver-derived samples were fatty acyls, fatty acid ethyl esters, glycerolipids and phosphatidylethanol homologues. Significant metabolites that were up-regulated by alcohol treatment in both rat and mouse livers included fatty acyls, metabolites such as octadecatrienoic acid and eicosapentaenoic acid, a number of fatty acid ethyl esters such as ethyl arachidonate, ethyl docosahexaenoic acid, ethyl linoleate and ethyl oleate and phosphatidylethanol (PEth) homologues (predominantly PEth 18:0/18:2 and PEth 16:0/18:2; PEth homologues are currently considered as potential biomarkers for harmful and prolonged alcohol consumption in man). A number of glycerophospholipids resulted in both up-regulation (m/z 903.7436 [M+H](+) corresponding to a triglyceride) and down-regulation (m/z 667.5296 [M+H](+) corresponding to a diglyceride). Metabolite profiles were broadly similar in both mouse and rat models. However, there were a number of significant differences in the alcohol-treated group particularly in the marked down-regulation of retinol and free cholesterol in the mouse compared to the rat. Unique markers for alcohol treatment included ethyl docosahexaenoic acid. Metabolites were identified with high confidence using predominantly negative ion MS(n) data for the fatty acyl components to match to www.lipidmaps.org MS and MS/MS databases; interpreting positive ion data needed to take into account possible adduct ions which may confound the identification of other lipid classes. The observed changes in lipid profiles were consistent with alcohol induced liver injury in humans

    Perturbative QCD studies of multijet structures in electron-positron annihilation

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    To investigate the effect in perturbative QCD of multigluon emissions on the transverse momentum distributions of multijet final states in electron-positron annihilation, we use a simplified model based on the approximation that gluons are emitted independently. As a guide to these multigluon emissions, we study the two-gluon contribution in some detail and calculate the Q(_T)-distribution for four-jet events in e(^+)e̅(^-)annihilation, using suitable jet-defining cuts, needed both theoretically, to regularize the soft- and collinear-gluon singularities, as well as experimentally, to group the final-state particles into distinct jets. To ascertain the accuracy of our approximate model, we compare our results with the exact ones, obtained by a Monte Carlo generation of events using the full matrix elements. We find that, for realistic values of the cuts, there is a significant kinematic region of agreement. This agreement and the validity of our model are further elaborated by taking its Abelian QCD limit, calculating distributions in other event shape variables and studying the jet broadening phenomenon. The applicability of our model is also delineated by finding it to be in remarkable structural and numerical agreement with the more exact algorithm of Altarelli et al. Finally, to investigate the effect of higher order and virtual graphs corrections to low order tree-level results, we use our model to calculate the O(a(^2)(_s)) Or-distribution for three-jet events in e(^+)e(^-) annihilation with virtual contributions included. We study the dependence of these corrections on the resolution parameters used to perform the (analytic) cancellation of infrared and collinear singularities between real and virtual graphs and discuss their physical consequences

    Classical quantum mechanics – particle is the pulse of matter waves

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    Since the very first development of Quantum Mechanics there are many scientists who, despite the fact that everything seems to work perfectly and the experimental results verify the theoretical predictions, do not understand what is really going on. That is why there are many different interpretations of this subject nowadays. This paper provides a new interpretation, aiming to illustrate the fact that Quantum Mechanics is actually an extension of Classical Physics, and in contrast to other interpretations we illustrate a possible experimental verification of theoretical wording

    Congestion and medium access control in 6LoWPAN WSN

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    In computer networks, congestion is a condition in which one or more egressinterfaces are offered more packets than are forwarded at any given instant [1]. In wireless sensor networks, congestion can cause a number of problems including packet loss, lower throughput and poor energy efficiency. These problems can potentially result in a reduced deployment lifetime and underperforming applications. Moreover, idle radio listening is a major source of energy consumption therefore low-power wireless devices must keep their radio transceivers off to maximise their battery lifetime. In order to minimise energy consumption and thus maximise the lifetime of wireless sensor networks, the research community has made significant efforts towards power saving medium access control protocols with Radio Duty Cycling. However, careful study of previous work reveals that radio duty cycle schemes are often neglected during the design and evaluation of congestion control algorithms. This thesis argues that the presence (or lack) of radio duty cycle can drastically influence the performance of congestion control mechanisms. To investigate if previous findings regarding congestion control are still applicable in IPv6 over low power wireless personal area and duty cycling networks; some of the most commonly used congestion detection algorithms are evaluated through simulations. The research aims to develop duty cycle aware congestion control schemes for IPv6 over low power wireless personal area networks. The proposed schemes must be able to maximise the networks goodput, while minimising packet loss, energy consumption and packet delay. Two congestion control schemes, namely DCCC6 (Duty Cycle-Aware Congestion Control for 6LoWPAN Networks) and CADC (Congestion Aware Duty Cycle MAC) are proposed to realise this claim. DCCC6 performs congestion detection based on a dynamic buffer. When congestion occurs, parent nodes will inform the nodes contributing to congestion and rates will be readjusted based on a new rate adaptation scheme aiming for local fairness. The child notification procedure is decided by DCCC6 and will be different when the network is duty cycling. When the network is duty cycling the child notification will be made through unicast frames. On the contrary broadcast frames will be used for congestion notification when the network is not duty cycling. Simulation and test-bed experiments have shown that DCCC6 achieved higher goodput and lower packet loss than previous works. Moreover, simulations show that DCCC6 maintained low energy consumption, with average delay times while it achieved a high degree of fairness. CADC, uses a new mechanism for duty cycle adaptation that reacts quickly to changing traffic loads and patterns. CADC is the first dynamic duty cycle pro- tocol implemented in Contiki Operating system (OS) as well as one of the first schemes designed based on the arbitrary traffic characteristics of IPv6 wireless sensor networks. Furthermore, CADC is designed as a stand alone medium access control scheme and thus it can easily be transfered to any wireless sensor network architecture. Additionally, CADC does not require any time synchronisation algorithms to operate at the nodes and does not use any additional packets for the exchange of information between the nodes (For example no overhead). In this research, 10000 simulation experiments and 700 test-bed experiments have been conducted for the evaluation of CADC. These experiments demonstrate that CADC can successfully adapt its cycle based on traffic patterns in every traffic scenario. Moreover, CADC consistently achieved the lowest energy consumption, very low packet delay times and packet loss, while its goodput performance was better than other dynamic duty cycle protocols and similar to the highest goodput observed among static duty cycle configurations

    Quantitation of endogenous metabolites in mouse tumors using mass-spectrometry imaging

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    Described is a quantitative-mass-spectrometryimaging (qMSI) methodology for the analysis of lactate and glutamate distributions in order to delineate heterogeneity among mouse tumor models used to support drug-discovery efficacy testing. We evaluate and report on preanalysisstabilization methods aimed at improving the reproducibility and efficiency of quantitative assessments of endogenous molecules in tissues. Stability experiments demonstrate that optimum stabilization protocols consist of frozen-tissue embedding, post-tissue-sectioning desiccation, and storage at −80 °C of tissue sections sealed in vacuum-tight containers. Optimized stabilization protocols are used in combination with qMSI methodology for the absolute quantitation of lactate and glutamate in tumors, incorporating the use of two different stable-isotope-labeled versions of each analyte and spectral-clustering performed on each tissue section using k-means clustering to allow region-specific, pixel-by-pixel quantitation. Region-specific qMSI was used to screen different tumor models and identify a phenotype that has low lactate heterogeneity, which will enable accurate measurements of lactate modulation in future drug-discovery studies. We conclude that using optimized qMSI protocols, it is possible to quantify endogenous metabolites within tumors, and region-specific quantitation can provide valuable insight into tissue heterogeneity and the tumor microenvironment
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