412 research outputs found
POISED: Spotting Twitter Spam Off the Beaten Paths
Cybercriminals have found in online social networks a propitious medium to
spread spam and malicious content. Existing techniques for detecting spam
include predicting the trustworthiness of accounts and analyzing the content of
these messages. However, advanced attackers can still successfully evade these
defenses.
Online social networks bring people who have personal connections or share
common interests to form communities. In this paper, we first show that users
within a networked community share some topics of interest. Moreover, content
shared on these social network tend to propagate according to the interests of
people. Dissemination paths may emerge where some communities post similar
messages, based on the interests of those communities. Spam and other malicious
content, on the other hand, follow different spreading patterns.
In this paper, we follow this insight and present POISED, a system that
leverages the differences in propagation between benign and malicious messages
on social networks to identify spam and other unwanted content. We test our
system on a dataset of 1.3M tweets collected from 64K users, and we show that
our approach is effective in detecting malicious messages, reaching 91%
precision and 93% recall. We also show that POISED's detection is more
comprehensive than previous systems, by comparing it to three state-of-the-art
spam detection systems that have been proposed by the research community in the
past. POISED significantly outperforms each of these systems. Moreover, through
simulations, we show how POISED is effective in the early detection of spam
messages and how it is resilient against two well-known adversarial machine
learning attacks
Beyond Eye Care – Low Vision Rehabilitation of a Patient with Recent-Onset Leber’s Hereditary Optic Neuropathy: A Case Report
Leber’s hereditary optic neuropathy (LHON) is a maternally inherited mitochondrial deoxyribonucleic acid (DNA) mutation that results in painless, sudden-onset, bilateral central vision loss and dyschromatopsia. Currently, there are no proven treatments to prevent or reverse the optic neuropathy in LHON. Accordingly, individualized rehabilitation services and assistive devices for low vision are crucial for helping people with LHON to regain independence and quality of life. This report describes the impact of multidisciplinary low vision rehabilitation on a young man with recent-onset LHON and emphasizes the importance of the provision of emotional support through counselling for low vision
“Introduction: Theory, Practice, and Critical Agency in Andrew Marvell’s Poetry
An introduction for the special issue on theoretical approaches to Andrew Marvell
Potentiel de la combustion partiellement prémélangée pour les moteurs essence
Carbon dioxide (CO₂) and other pollutant emission limitations are more and more rigorous. These limits conduct cars manufacturers to study new combustion concept, in order to increase conventional gasoline engine efficiencies. Gasoline Partially premixed combustion concept (GPPC) seems to have the potential to reach these objectives, in other terms an efficiencies comparable to diesel engine by with emissions of gasoline engine, which mean a low cost after-treatment system. This study investigates, by an experimental approach, the physical process responsible on controlling this combustion concept and by the way improves it. This will be done by studying the mixture preparation and the combustion behaviour. The first part of this work concerns on determining the impact of in-cylinder thermodynamic conditions, injection strategy and the dilution rate on combustion behaviour using a single cylinder all metal engine. Three distinctive heat release rates were selected; where one represent the optimized injection phasing in term of efficiencies and pollutant emissions. The second part was dedicated to studying the process involved in GPPC combustion mode by optical diagnostic techniques on single cylinder optical access diesel engine. The impact of second injection phasing, fuel and air interaction and also the fuel combustion process allowed the validation of hypothesis emitted in the first part to explain the combustion behaviour and give ways to control this combustion mode.La limitation des rejets en CO₂ associés aux normes européennes antipollution de plus en plus sévères ont conduit les constructeurs automobiles à innover dans de nouveaux concepts de combustion, dans l’objectif d’augmenter le rendement des moteurs essence conventionnels. La combustion de type Partiellement Prémélangée, communément appelée Gasoline Partially Premixed Combustion (soit GPPC) semble être l’un des possibilités pour répondre à ces problématiques, en particulier s’il était possible d’atteindre un rendement proche des rendements Diesel avec des émissions polluantes plutôt de type moteur à allumage commandé et qui pourraient donc être traitées par systèmes de post-traitement classiques. Cette étude vise, par une approche expérimentale, à comprendre les processus physiques qui permettent d’optimiser ce nouveau mode de combustion, en particulier en termes de préparation du mélange et de déroulement de la combustion proprement dite. La première partie de ce travail a consisté en la détermination de l’impact des différentes conditions thermodynamiques, de la stratégie d’injections et du taux de dilution sur le déroulement de la combustion à partir de données obtenues sur un moteur opaque. Trois modes de dégagements de chaleur très distincts ont été sélectionnés, l’un représentant la configuration optimale en termes de rendement et d’émissions polluantes à partir d’expériences réalisées sur moteur monocylindre à fort taux de compression et avec une chambre typée Diesel. Des techniques de diagnostics optiques ont été mises en place sur un moteur identique mais à accès optiques dans l’objectif d’isoler tout particulièrement l’impact du phasage de la seconde injection sur le déroulement de la combustion. L’étude de la propagation liquide du spray lors de l’injection, de l’interaction entre l’air et le carburant lors du processus de formation du mélange et de la phase d’oxydation du carburant a ainsi pu être réalisée et a permis de valider les hypothèses émises lors des essais sur moteur opaque pour expliquer les processus de combustion et donner des pistes de contrôle de ce type de combustion
Guest Editorial: Student Satisfaction with Experiential Learning in External Geriatrics and External Paediatrics
Forme architecturale et confort hygrothermique dans les bâtiments éducatifs, cas des infrastructures d’enseignement supérieur en régions arides
Avec les préoccupations grandissantes du développement durable, le secteur du bâtiment doit répondre à deux exigences fondamentales : maîtriser à la fois les impacts sur l’environnement extérieur, et s’assurer des ambiances intérieures saines et confortables pour les occupants.
Dans les bâtiments éducatifs qui représentent une catégorie d’équipements, qui révèle une importance clé, vu le rôle que joue l’éducation dans le développement des individus et des sociétés, un environnement confortable et adéquat à l’éducation doit être assuré.
Le confort hygrothermique est l’une des principales caractéristiques qui contribuent à la création d’un environnement propice à l’éducation. Il doit être pris en considération en raison des influences négatives d’un environnement thermique insuffisant sur la performance d’apprendre.
La qualité du confort hygrothermique doit être prise en compte lors des phases initiales de la conception.
La présente étude vise principalement à évaluer et mesurer l’impact de la forme architecturale des bâtiments d’enseignement, dans les universités, sur le confort hygrothermique des étudiants sous un climat aride et participe, à la fois, à améliorer la performance d’apprendre et à limiter voir éviter le recours à des solutions actives du conditionnement gros consommateurs d’énergie. Elle tend aussi à déterminer à la fin, parmi les formes les plus récurrentes des bâtiments d’enseignement, celles jugées comme plus performantes en matière de réponse aux exigences du confort hygrothermique pour les étudiants sous les conditions d’un climat chaud et sec.
Dans le but d’atteindre ces objectifs, l’étude est basée sur la méthode expérimentale à travers la technique de simulation via le logiciel Ecotect@ version 2011, et la méthode d’enquête à travers la technique du questionnaire auto-administré. Ces deux techniques permettent d’évaluer les deux aspects du confort hygrothermique, quantitatif et qualitatif, dans les salles de classe des blocs d’enseignement (blocs de TD) de l’université de Biskra choisie comme cas d’étude
Hearing and Vision Screening Tools for Long-Term Care Residents with Dementia: Protocol for a Scoping Review
Introduction: Hearing and vision loss among longterm care (LTC) residents with dementia frequently goes unnoticed and untreated. Despite negative consequences for these residents, there is little information available about their sensory abilities and care assessments and practices seldom take these abilities or accessibility needs into account. Without adequate knowledge regarding such sensory loss, it is difficult for LTC staff to determine the level of an individual’s residual basic competence for communication and independent functioning. We will conduct a scoping review to identify the screening measures used in research and clinical contexts that test hearing and vision in adults aged over 65 years with dementia, aiming to: (1) provide an overview of hearing and vision screening in older adults with dementia; and (2) evaluate the sensibility of the screening tools. Methods and analysis: This scoping review will be conducted using the framework by Arksey and O’Malley and furthered by methodological enhancements from cited researchers. We will conduct electronic database searches in CENTRAL, CINAHL, EMBASE, MEDLINE and PsycINFO. We will also carry out a ‘grey literature’ search for studies or materials not formally published, both online and through interview discussions with healthcare professionals and research clinicians working in the field. Our aim is to find new and existing hearing and vision screening measures used in research and by clinical professionals of optometry and audiology. Abstracts will be independently reviewed twice for acceptance by a multidisciplinary team of researchers and research clinicians. Ethics and dissemination: This review will inform health professionals working with this growing population. With the review findings, we aim to develop a toolkit and an algorithmic process to select the most appropriate hearing and vision screening assessments for LTC residents with dementia that will facilitate accurate testing and can inform care planning, thereby improving residents’ quality of life
Ambient exposures to selected volatile organic compounds and the risk of prostate cancer in Montreal
Background:Little is known about environmental factors that may increase the risk of prostate cancer. We estimated associations between incident prostate cancer and environmental concentrations of five ambient volatile organic compounds (VOCs): benzene; n-decane; ethylbenzene; hexane; and 1,2,4-trimethylbenzene. Methods:This study is based on a population-based case-control study of incident prostate cancer (PROtEuS) in men <= 75 years of age living in Montreal, Canada, in 2005 to 2012. We included 1172 cases and 1177 population controls. We had personal information, lifetime residential addresses, occupational exposures, and a variety of area-wide covariables. We inferred concentrations of the five VOCs using Bayesian geostatistical models using data from a dense environmental survey conducted in Montreal in 2005 to 2006. We used different sets of adjustments to estimate odds ratios (OR) and confidence intervals. Results:We found nonlinear associations such that the ORs increased monotonically and then either flattened or fell off with increased exposures. The model that contained other environmental variables and contextual variables led to lower ORs and results were similar when we restricted analyses to controls recently screened or tested for prostate cancer or cases with low- or high-grade tumors. A change from the 5th to 25th percentile in mean environmental benzene levels led to an adjusted OR of 2.00 (95% confidence interval = 1.47, 2.71). Conclusion:We found positive associations between prostate cancer and concentrations of benzene and ethylbenzene, independently of previous testing for prostate cancer or tumor grade, suggesting that exposure to certain ambient VOCs may increase incidence.</br
Spatial modeling of ambient concentrations of volatile organic compounds in Montreal, Canada
Background: Volatile organic compounds (VOCs) are components of the complex mixture of air pollutants within cities and can cause various adverse health effects. Therefore, it is necessary to understand their spatial distribution for exposure assessment in epidemiological studies. Objectives: The objective was to model measured concentrations of five VOCs within the city of Montreal, Canada, developing spatial prediction models that can be used in health studies. Methods: We measured concentrations using 3M 3500 Organic Vapor Monitors, over 2-week periods, for three monitoring campaigns between 2005 and 2006 in over 130 locations in the city. Using GC/MSD (Gas Chromatography/Mass Selective Detector), we measured concentrations of benzene, n-decane, ethylbenzene, hexane, and trimethylbenzene. We fitted four different models that combine land-use regression and geostatistical methods to account for the potential spatial structure that remains after accounting for the land-use variables. The fitted models also accounted for possible variations in the concentration of air pollutants across campaigns. Results: The highest concentrations for all VOCs were found in December with hexane being the most abundant followed by ethylbenzene. We obtained predicted surfaces for the VOCs for the three campaigns and mean surfaces across campaigns. We found higher concentrations of some VOCs along highways and in the Eastern part of Montreal, which is a highly industrialized area. Conclusions: Each of the fitted models captured the spatial and across-campaigns variability for each VOC, and we found that different VOCs required different model structures.</br
Impact of tetrachloroethylene-contaminated drinking water on the risk of breast cancer: Using a dose model to assess exposure in a case-control study
BACKGROUND: A population-based case-control study was undertaken in 1997 to investigate the association between tetrachloroethylene (PCE) exposure from public drinking water and breast cancer among permanent residents of the Cape Cod region of Massachusetts. PCE, a volatile organic chemical, leached from the vinyl lining of certain water distribution pipes into drinking water from the late 1960s through the early 1980s. The measure of exposure in the original study, referred to as the relative delivered dose (RDD), was based on an amount of PCE in the tap water entering the home and estimated with a mathematical model that involved only characteristics of the distribution system. METHODS: In the current analysis, we constructed a personal delivered dose (PDD) model that included personal information on tap water consumption and bathing habits so that inhalation, ingestion, and dermal absorption were also considered. We reanalyzed the association between PCE and breast cancer and compared the results to the original RDD analysis of subjects with complete data. RESULTS: The PDD model produced higher adjusted odds ratios than the RDD model for exposures > 50(th )and >75(th )percentile when shorter latency periods were considered, and for exposures < 50(th )and >90(th )percentile when longer latency periods were considered. Overall, however, the results from the PDD analysis did not differ greatly from the RDD analysis. CONCLUSION: The inputs that most heavily influenced the PDD model were initial water concentration and duration of exposure. These variables were also included in the RDD model. In this study population, personal factors like bath and shower temperature, bathing frequencies and durations, and water consumption did not differ greatly among subjects, so including this information in the model did not significantly change subjects' exposure classification
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