16,052 research outputs found

    A predefined channel coefficients library for vehicle-to-vehicle communications

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    It is noticeable that most of VANETs communications tests are assessed through simulation. In a majority of simulation results, the physical layer is often affected by an apparent lack of realism. Therefore, vehicular channel model has become a critical issue in the field of intelligent transport systems (ITS). To overcome the lack of realism problem, a more robust channel model is needed to reflect the reality. This paper provides an open access, predefined channel coefficients library. The library is based on 2x2 and 4x4 Multiple – Input – Multiple – Output (MIMO) systems in V2V communications, using a spatial channel model extended SCME which will help to reduce the overall simulation time. In addition, it provides a more realistic channel model for V2V communications; considering: over ranges of speeds, distances, multipath signals, sub-path signals, different angle of arrivals, different angle departures, no line of sight and line of sight. An intensive evaluation process has taken place to validate the library and acceptance results are produced. Having an open access predefined library, enables the researcher at relevant communities to test and evaluate several complicated vehicular communications scenarios in a wider manners with less time and efforts

    Predictors of breastfeeding duration among women in Kuwait: results of a prospective cohort study

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    The purposes of this paper are to report the prevalence of breastfeeding to six months among women in Kuwait and to determine the factors that are associated with the duration of breastfeeding. A cohort of 373 women recruited from maternity wards in four hospitals in Kuwait city were followed from birth to 26 weeks postpartum. The association of any and full breastfeeding duration and predictor variables were explored using multivariate Cox’s proportional hazards models. At six months, 39% of all infants were receiving some breast milk and only 2% of infants had been fully breastfed to 26 weeks. Women born in other Arab countries were less likely to discontinue breastfeeding than women born in Kuwait. Other factors positively associated with breastfeeding duration were level of maternal education, higher parity, infant being demand fed in hospital and a preference for breastfeeding on the part of the infant’s father and maternal grandmother. The introduction of a pacifier before four weeks of age and the mother intending to return to work by six months were negatively associated with duration. These findings present a number of opportunities for prolonging breastfeeding duration in Kuwait

    Satisfaction and quality of life in women who undergo breast surgery: a qualitative study to develop conceptual model

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    Background: In cosmetic and reconstructive breast surgery, measurement of patient-reported outcomes has become increasingly important to research efforts and clinical care. We aimed to describe how breast conditions and breast surgery impact on patient satisfaction and quality of life. Methods: We conducted qualitative, in-depth interviews with 48 women who had undergone either breast reduction (n = 15), breast augmentation (n = 12), or breast reconstruction (n = 21) surgery in order to begin to build a theoretical understanding of patient satisfaction and quality of life in breast surgery patients. Interviews were audio-taped, transcribed verbatim and analyzed thematically. Results: The patient interviews revealed that breast conditions and breast surgery impact women in the following six main areas: satisfaction with breasts; satisfaction with overall outcome; psychosocial well-being; sexual well-being; physical well-being; and satisfaction with the process of care. We used these six themes to form the basis of a conceptual framework of patient satisfaction and quality of life in women who undergo breast surgery. Conclusion: Our conceptual framework establishes the main issues of concern for breast surgery patients. This new framework can be used to help develop local guidelines for future clinical assessment, management and measurement, establish the validity of the current management strategies, and develop evidence-based guidance for the development of new patient reported outcome measures for future outcomes research

    Sub 1GHz M2M communications standardization: The advancement in white space utilization for enhancing the energy efficiency

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    Energy efficiency of machine to machine (M2M) communications terminals is one of the major design goals of M2M networks, resulting from anticipated over 50 billion M2M communications devices to be deployed into the networks by 2020 [1]. The stakeholders in the M2M communications have observed that it will be environmental and economic catastrophic to deploy M2M communications devices without solving the energy inefficiencies associated with wireless devices that are expected to be used for M2M communications. In view of the aforementioned energy challenge, sub 1GHz spectra have provided enormous opportunities that can be energy efficient, cost effective and coverage efficiency which can be utilized for M2M communications. This work will evaluate the energy efficiency benefits of optimized Sub 1GHz spectra for M2M communications

    Characterization of Freshwater Natural Dissolved Organic Matter (DOM): Mechanistic Explanations for Protective Effects Against Metaltoxicity and Direct Effects on Organisms

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    Dissolved organic matter (DOM) exerts direct and indirect influences on aquatic organisms. In order to better understand how DOM causes these effects, potentiometric titration was carried out for a wide range of autochthonous and terrigenous freshwater DOM isolates. The isolates were previously characterized by absorbance and fluorescence spectroscopy. Proton binding constants (pKa) were grouped into three classes:acidic (pKa ≤ 5), intermediate (5 \u3c pKa ≤ 8.5) and basic (pKa \u3e 8.5). Generally, the proton site densities (LT) showed maximum peaks at the acidic and basic ends around pKa values of 3.5 and 10, respectively. More variably positioned peaks occurred in the intermediate pKa range. The acid–base titrations revealed the dominance of carboxylic and phenolic ligands with a trend for more autochthonous sources to have higher total LT. A summary parameter, referred to as the Proton Binding Index (PBI), was introduced to summarize chemical reactivity of DOMs based on the data of pKa and LT. Then, the already published spectroscopic data were explored and the specific absorbance coefficient at 340 nm (i.e. SAC340), an index of DOM aromaticity,was found to exhibit a strong correlation with PBI. Thus, the tendencies observed in the literature that darker organic matter is more protective against metal toxicity and more effective in altering physiological processes in aquatic organisms can now be rationalized on a basis of chemical reactivity to protons

    The Influence of Dissolved Organic Matter (DOM) on Sodium Regulation and Nitrogenous Waste Excretion in the Zebrafish (Danio rerio)

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    Dissolved organic matter (DOM) is both ubiquitous and diverse in composition in natural waters, but its effects on the branchial physiology of aquatic organisms have received little attention relative to other variables (e.g. pH, hardness, salinity, alkalinity). Here, we investigated the effects of four chemically distinct DOM isolates (three natural, one commercial, ranging from autochthonous to highly allochthonous, all at ∼6 mg C l−1) on the physiology of gill ionoregulation and nitrogenous waste excretion in zebrafish acclimated to either circumneutral (7.0–8.0) or acidic pH (5.0). Overall, lower pH tended to increase net branchial ammonia excretion, net K+ loss and [3H]PEG-4000 clearance rates (indicators of transcellular and paracellular permeability, respectively). However, unidirectional Na+ efflux, urea excretion and drinking rates were unaffected. DOM sources tended to stimulate unidirectional Na+ influx rate and exerted subtle effects on the concentration-dependent kinetics of Na+ uptake, increasing maximum transport capacity. All DOM sources reduced passive Na+ efflux rates regardless of pH, but exerted negligible effects on nitrogenous waste excretion, drinking rate, net K+ loss or [3H]PEG4000 clearance, so the mechanism of Na+ loss reduction remains unclear. Overall, these actions appear beneficial to ionoregulatory homeostasis in zebrafish, and some may be related to physicochemical properties of the DOM sources. They are very different from those seen in a recent parallel study on Daphnia magna using the same DOM isolates, indicating that DOM actions may be both species and DOM specific

    A Chromosomal Deletion and New Frameshift Mutation Cause ARSACS in an African-American

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    Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay (ARSACS) is a rare, progressive, neurodegenerative disease characterized by ataxia, spasticity and polyneuropathy. First described in the French-Canadian population of Quebec in 1978, ARSACS has since been identified in multiple patients worldwide. In this clinical case report, we describe the evaluation of an 11-years-old African-American male who presented to neuromuscular clinic for assessment of a gait abnormality. He had a history of gross motor delay since early childhood, frequent falls and a below average IQ. Chromosomal microarray revealed a 1.422 megabase loss in the 13q12.12 region, which includes the SACS gene. Next Generation Sequencing then showed a novel, predicted to be pathogenic missense mutation (c.11824dup) of this gene. His clinical presentation and neurological imaging further confirmed the diagnosis of ARSACS. To our knowledge, this is the first reported case of this disease in the African-American population of the United States. This case report further highlights the growing trend of identifying genetic diseases previously restricted to single, ethnically isolated regions in many different ethnic groups worldwide

    Employing VANET technology to alleviate road congestion in real time

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    Nowadays, traffic road jams are considered one of the most serious problems facing a large group of people, where many drivers die or are exposed to serious injuries because of road accidents that occur due to road congestion, driver's behaviour by disobeying the rules and traffic lights or bad management for traffic system. The eagerness on developing the deployment traffic road information among vehicles to reduce road accident and to make the journey more safe was the main motivation behind the improvement of Vehicular Ad Hoc Networks VANETs. VANETs are a special category of Mobile Ad Hoc Networks (MANET), which considered the cornerstone for Intelligent Transportation System (ITS) that used to established communication among vehicles on a road using an infrastructure-less network. On this study, we will use graph model representation to design a novel algorithm which can deal with Instantaneous accident/incident occasions, road works and roads amendments to provide instant actions list to the transportation team to reduce congestion in shorter time, and to use wireless access technologies to send individual message to the relevant vehicles to avoid the congestion through Road Side Units (RSUs) devices. The aim of this research is to develop Intelligent Transportation System (ITS) for a city (e.g. Northampton) using VANETs technology, specifically vehicle to infrastructure communications which lead to reducing the traffic congestion or mitigation. The performance of proposed study will be evaluated via various congested scenarios using simulations software (Omnet++, SUMO and Veins) to assess the validity of the proposed algorithm

    Process of Developing the Artificial Snow Machine System

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    In order to test different types of anti-icing fluids that are used on aircraft surfaces prior to take off, it is necessary to develop a machine that artificially generates snow. Deicing aircraft is a two-step process that consists of applying both deicing and anti-icing fluids. Deicing fluids are applied to eliminate accumulated ice on aircraft surfaces that could obstruct proper airflow. Anti-icing fluids are then applied to prevent the additional accumulation of frost, ice, and/or snow for a period of time known as the endurance time. The endurance time is the duration the anti-icing fluid remains effective on the aircraft surface. Results from the snow machine tests have shown that it accurately replicates natural snowfall, and allows for repeated, controlled-environment testing throughout the year. Variables controlled include wind speed, air temperature, and liquid-water equivalent snowfall (LWE) rates. The machine is also affordable and more efficient than outdoor testing. In order to continue studying the factors that influence endurance time and accumulation rates, the design of the existing snow machine has been modified to increase effectiveness and efficiency. Aluminum struts make up the framework of the snow machine which measures 2.75m tall with a base of 0.91m by 0.66m and are bolted at the midpoints for structural integrity. The sides are made of clear Plexiglass which slide into the frame rather than being attached from the outside with hinges. This eliminates excessive construction material and provides a better appearance. The top of the machine is cut into 45° angles to evenly fit and level the pieces of struts, whereas, the previous model had overlapping struts that formed gaps between overlaid pieces of the frame. Finally, wheels were added for easy transport. These modifications, along with software improvements are targeted for additional testing in the near future
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