57 resultados para Castellion, Sébastien, 1515-1563
Resumo:
Recent road safety statistics show that the decades-long fatalities decreasing trend is stopping and stagnating. Statistics further show that crashes are mostly driven by human error, compared to other factors such as environmental conditions and mechanical defects. Within human error, the dominant error source is perceptive errors, which represent about 50% of the total. The next two sources are interpretation and evaluation, which accounts together with perception for more than 75% of human error related crashes. Those statistics show that allowing drivers to perceive and understand their environment better, or supplement them when they are clearly at fault, is a solution to a good assessment of road risk, and, as a consequence, further decreasing fatalities. To answer this problem, currently deployed driving assistance systems combine more and more information from diverse sources (sensors) to enhance the driver's perception of their environment. However, because of inherent limitations in range and field of view, these systems' perception of their environment remains largely limited to a small interest zone around a single vehicle. Such limitations can be overcomed by increasing the interest zone through a cooperative process. Cooperative Systems (CS), a specific subset of Intelligent Transportation Systems (ITS), aim at compensating for local systems' limitations by associating embedded information technology and intervehicular communication technology (IVC). With CS, information sources are not limited to a single vehicle anymore. From this distribution arises the concept of extended or augmented perception. Augmented perception allows extending an actor's perceptive horizon beyond its "natural" limits not only by fusing information from multiple in-vehicle sensors but also information obtained from remote sensors. The end result of an augmented perception and data fusion chain is known as an augmented map. It is a repository where any relevant information about objects in the environment, and the environment itself, can be stored in a layered architecture. This thesis aims at demonstrating that augmented perception has better performance than noncooperative approaches, and that it can be used to successfully identify road risk. We found it was necessary to evaluate the performance of augmented perception, in order to obtain a better knowledge on their limitations. Indeed, while many promising results have already been obtained, the feasibility of building an augmented map from exchanged local perception information and, then, using this information beneficially for road users, has not been thoroughly assessed yet. The limitations of augmented perception, and underlying technologies, have not be thoroughly assessed yet. Most notably, many questions remain unanswered as to the IVC performance and their ability to deliver appropriate quality of service to support life-saving critical systems. This is especially true as the road environment is a complex, highly variable setting where many sources of imperfections and errors exist, not only limited to IVC. We provide at first a discussion on these limitations and a performance model built to incorporate them, created from empirical data collected on test tracks. Our results are more pessimistic than existing literature, suggesting IVC limitations have been underestimated. Then, we develop a new CS-applications simulation architecture. This architecture is used to obtain new results on the safety benefits of a cooperative safety application (EEBL), and then to support further study on augmented perception. At first, we confirm earlier results in terms of crashes numbers decrease, but raise doubts on benefits in terms of crashes' severity. In the next step, we implement an augmented perception architecture tasked with creating an augmented map. Our approach is aimed at providing a generalist architecture that can use many different types of sensors to create the map, and which is not limited to any specific application. The data association problem is tackled with an MHT approach based on the Belief Theory. Then, augmented and single-vehicle perceptions are compared in a reference driving scenario for risk assessment,taking into account the IVC limitations obtained earlier; we show their impact on the augmented map's performance. Our results show that augmented perception performs better than non-cooperative approaches, allowing to almost tripling the advance warning time before a crash. IVC limitations appear to have no significant effect on the previous performance, although this might be valid only for our specific scenario. Eventually, we propose a new approach using augmented perception to identify road risk through a surrogate: near-miss events. A CS-based approach is designed and validated to detect near-miss events, and then compared to a non-cooperative approach based on vehicles equiped with local sensors only. The cooperative approach shows a significant improvement in the number of events that can be detected, especially at the higher rates of system's deployment.
Resumo:
This paper presents a model for the generation of a MAC tag using a stream cipher. The input message is used indirectly to control segments of the keystream that form the MAC tag. Several recent proposals can be considered as instances of this general model, as they all perform message accumulation in this way. However, they use slightly different processes in the message preparation and finalisation phases. We examine the security of this model for different options and against different types of attack, and conclude that the indirect injection model can be used to generate MAC tags securely for certain combinations of options. Careful consideration is required at the design stage to avoid combinations of options that result in susceptibility to forgery attacks. Additionally, some implementations may be vulnerable to side-channel attacks if used in Authenticated Encryption (AE) algorithms. We give design recommendations to provide resistance to these attacks for proposals following this model.
Resumo:
Non-linear feedback shift register (NLFSR) ciphers are cryptographic tools of choice of the industry especially for mobile communication. Their attractive feature is a high efficiency when implemented in hardware or software. However, the main problem of NLFSR ciphers is that their security is still not well investigated. The paper makes a progress in the study of the security of NLFSR ciphers. In particular, we show a distinguishing attack on linearly filtered NLFSR (or LF-NLFSR) ciphers. We extend the attack to a linear combination of LF-NLFSRs. We investigate the security of a modified version of the Grain stream cipher and show its vulnerability to both key recovery and distinguishing attacks.
Resumo:
IEEE 802.11p is the new standard for Inter-Vehicular Communications (IVC) using the 5.9 GHz frequency band, as part of the DSRC framework; it will enable applications based on Cooperative Systems. Simulation is widely used to estimate or verify the potential benefits of such cooperative applications, notably in terms of safety for the drivers. We have developed a performance model for 802.11p that can be used by simulations of cooperative applications (e.g. collision avoidance) without requiring intricate models of the whole IVC stack. Instead, it provide a a straightforward yet realistic modelisation of IVC performance. Our model uses data from extensive field trials to infer the correlation between speed, distance and performance metrics such as maximum range, latency and frame loss. Then, we improve this model to limit the number of profiles that have to be generated when there are more than a few couples of emitter-receptor in a given location. Our model generates realistic performance for rural or suburban environments among small groups of IVC-equipped vehicles and road side units.
Resumo:
Arrangement-making is understood to be a ‘closing-relevant action’ (Schegloff & Sacks 1973), but little attention has been given to how people arrive at mutually acceptable plans for the future. Telephone conversations between clients and staff of Community and Home Care (CHC) services were studied to identify how arrangements for future services were made. A recurrent sequence was observed in which clients were informed of future arrangement and were prompted to reply with ‘response solicitation’ (Jefferson 1981). Response solicitations were observed at two points: either tagged to the end of an informing, or following a recipient’s response to the informing. We show how response solicitations are routinely used in instances where recipients have some discretion in relation to the arrangement under discussion. They are a means by which an informing party can display to their interlocutor that they, as recipient, have some discretion to exercise in the matter. These findings are discussed with reference to prior research on arrangement-making in other settings, which suggests the general nature of this practice.
Resumo:
Since their introduction, the notions of indistinguishability and non-malleability have been changed and extended by different authors to support different goals. In this paper, we propose new flavors of these notions, investigate their relative strengths with respect to previous notions, and provide the full picture of relationships (i.e., implications and separations) among the security notions for public-key encryption schemes. We take into account the two general security goals of indistinguishability and non-malleability, each in the message space, key space, and hybrid message-key space to find six specific goals, a couple of them, namely complete indistinguishability and key non-malleability, are new. Then for each pair of goals, coming from the indistinguishability or non-malleability classes, we prove either an implication or a separation, completing the full picture of relationships among all these security notions. The implications and separations are respectively supported by formal proofs (i.e., reductions) in the concrete-security framework and by counterexamples.
Resumo:
Oncogene-induced senescence (OIS) is a potent tumor-suppressive mechanism that is thought to come at the cost of aging. The Forkhead box O (FOXO) transcription factors are regulators of life span and tumor suppression. However, whether and how FOXOs function in OIS have been unclear. Here, we show a role for FOXO4 in mediating senescence by the human BRAFV600E oncogene, which arises commonly in melanoma. BRAFV600E signaling through mitogen-activated protein kinase/extracellular signal-regulated kinase kinase resulted in increased reactive oxygen species levels and c-Jun NH 2 terminal kinase-mediated activation of FOXO4 via its phosphorylation on Thr223, Ser226, Thr447, and Thr451. BRAFV600E-induced FOXO4 phosphorylation resulted in p21cip1-mediated cell senescence independent of p16 ink4a or p27kip1. Importantly, melanocyte-specific activation of BRAFV600E in vivo resulted in the formation of skin nevi expressing Thr223/Ser226-phosphorylated FOXO4 and elevated p21cip1. Together, these findings support a model in which FOXOs mediate a trade-off between cancer and aging.
Resumo:
Technical dinitrotoluene (DNT) is a mixture of 2,4- and 2,6-DNT. In humans, industrial or environmental exposure can occur orally, by inhalation, or by skin contact. The classification of DNT as an 'animal carcinogen' is based on the formation of malignant tumors in kidneys, liver, and mammary glands of rats and mice. Clear signs of toxic nephropathy were found in rats dosed with DNT, and the concept was derived of an interrelation between renal toxicity and carcinogenicity. Recent data point to the carcinogenicity of DNT on the urinary tract of exposed humans. Between 1984 and 1997, 6 cases of urothelial cancer and 14 cases of renal cell cancer were diagnosed in a group of 500 underground mining workers in the copper mining industry of the former GDR and having high exposures to explosives containing technical DNT. The incidences of both urothelial and renal cell tumors in this group were 4.5 and 14.3 times higher, respectively, than anticipated on the basis of the cancer registers of the GDR. The genotyping of all identified tumor patients for the polymorphic enzymes NAT2, GSTM1, and GSTT1 identified the urothelial tumor cases as exclusively 'slow acetylates'. A group of 161 miners highly exposed to DNT was investigated for signs of subclinical renal damage. The exposures were categorized semi-quantitatively into 'low', 'medium', 'high', and 'very high'. A straight dose-dependence of the excretion of urinary biomarker proteins with the ranking of exposure was seen. Biomarker excretion (alpha1-microglobulin, glutathione S-transferases alpha and pi) indicated that DNT-induced damage was directed toward the tubular system. New data on DNT-exposed humans appear consistent with the concept of cancer initiation by DNT isomers and the subsequent promotion of renal carcinogenesis by selective damage to the proximal tubule. The differential pathways of metabolic activation of DNT appear to apply to the proximal tubule of the kidney and to the urothelium of the renal pelvis and lower urinary tract as target tissues of carcinogenicity.
Resumo:
Occupational standards concerning the allowable concentrations of chemical compounds in the ambient air of workplaces have been established in several countries at national levels. With the integration of the European Union, a need exists for establishing harmonized Occupational Exposure Limits. For analytical developments, it is apparent that methods for speciation or fractionation of carcinogenic metal compounds will be of increasing practical importance for standard setting. Criteria of applicability under field conditions, cost-effectiveness, and robustness are practical driving forces for new developments. When the European Union issued a list of 62 chemical substances with Occupational Exposure Limits in 2000, 25 substances received a 'skin' notation. The latter indicates that toxicologically significant amounts may be taken up via the skin. Similar notations exist on national levels. For such substances, monitoring concentrations in ambient air will not be sufficient; biological monitoring strategies will gain further importance in the medical surveillance of workers who are exposed to such compounds. Proceedings in establishing legal frameworks for a biological monitoring of chemical exposures within Europe are paralleled by scientific advances in this field. A new aspect is the possibility of a differential adduct monitoring, using blood proteins of different half-life or lifespan. This technique allows differentiation between long-term mean exposure to reactive chemicals and short-term episodes, for example, by accidental overexposure. For further analytical developments, the following issues have been addressed as being particularly important: New dose monitoring strategies, sensitive and reliable methods for detection of DNA adducts, cytogenetic parameters in biological monitoring, methods to monitor exposure to sensitizing chemicals, and parameters for individual susceptibilities to chemical toxicants.
Resumo:
Scholarly research into the uses of social media has become a major area of growth in recent years, as the adoption of social media for public communication itself has continued apace. While social media platforms provide ready avenues for data access through their Application Programming interfaces, it is increasingly important to think through exactly what these data represent, and what conclusions about the role of social media in society the research which is based on such data therefore enables. This article explores these issues especially for one of the currently leading social media platforms: Twitter.
Resumo:
Summary 1. Acoustic methods are used increasingly to survey and monitor bat populations. However, the use of acoustic methods at continental scales can be hampered by the lack of standardized and objective methods to identify all species recorded. This makes comparable continent-wide monitoring difficult, impeding progress towards developing biodiversity indicators, transboundary conservation programmes and monitoring species distribution changes. 2. Here we developed a continental-scale classifier for acoustic identification of bats, which can be used throughout Europe to ensure objective, consistent and comparable species identifications. We selected 1350 full-spectrum reference calls from a set of 15 858 calls of 34 European species, from EchoBank, a global echolocation call library. We assessed 24 call parameters to evaluate how well they distinguish between species and used the 12 most useful to train a hierarchy of ensembles of artificial neural networks to distinguish the echolocation calls of these bat species. 3. Calls are first classified to one of five call-type groups, with a median accuracy of 97·6%. The median species-level classification accuracy is 83·7%, providing robust classification for most European species, and an estimate of classification error for each species. 4. These classifiers were packaged into an online tool, iBatsID, which is freely available, enabling anyone to classify European calls in an objective and consistent way, allowing standardized acoustic identification across the continent. 5. Synthesis and applications. iBatsID is the first freely available and easily accessible continental- scale bat call classifier, providing the basis for standardized, continental acoustic bat monitoring in Europe. This method can provide key information to managers and conservation planners on distribution changes and changes in bat species activity through time.
Resumo:
The 15 members of the kallikrein-related serine peptidase (KLK) family have diverse tissue-specific expression profiles and roles in a range of cellular processes, including proliferation, migration, invasion, differentiation, inflammation and angiogenesis that are required in both normal physiology as well as pathological conditions. These roles require cleavage of a range of substrates, including extracellular matrix proteins, growth factors, cytokines as well as other proteinases. In addition, it has been clear since the earliest days of KLK research that cleavage of cell surface substrates is also essential in a range of KLK-mediated cellular processes where these peptidases are essentially acting as agonists and antagonists. In this review we focus on these KLK-regulated cell surface receptor systems including bradykinin receptors, proteinase-activated receptors, as well as the plasminogen activator, ephrins and their receptors, and hepatocyte growth factor/Met receptor systems and other plasma membrane proteins. From this analysis it is clear that in many physiological and pathological settings KLKs have the potential to regulate multiple receptor systems simultaneously; an important issue when these peptidases and substrates are targeted in disease.
Resumo:
INTRODUCTION: The first South African National Burden of Disease study quantified the underlying causes of premature mortality and morbidity experienced in South Africa in the year 2000. This was followed by a Comparative Risk Assessment to estimate the contributions of 17 selected risk factors to burden of disease in South Africa. This paper describes the health impact of exposure to four selected environmental risk factors: unsafe water, sanitation and hygiene; indoor air pollution from household use of solid fuels; urban outdoor air pollution and lead exposure. METHODS: The study followed World Health Organization comparative risk assessment methodology. Population-attributable fractions were calculated and applied to revised burden of disease estimates (deaths and disability adjusted life years, [DALYs]) from the South African Burden of Disease study to obtain the attributable burden for each selected risk factor. The burden attributable to the joint effect of the four environmental risk factors was also estimated taking into account competing risks and common pathways. Monte Carlo simulation-modeling techniques were used to quantify sampling, uncertainty. RESULTS: Almost 24 000 deaths were attributable to the joint effect of these four environmental risk factors, accounting for 4.6% (95% uncertainty interval 3.8-5.3%) of all deaths in South Africa in 2000. Overall the burden due to these environmental risks was equivalent to 3.7% (95% uncertainty interval 3.4-4.0%) of the total disease burden for South Africa, with unsafe water sanitation and hygiene the main contributor to joint burden. The joint attributable burden was especially high in children under 5 years of age, accounting for 10.8% of total deaths in this age group and 9.7% of burden of disease. CONCLUSION: This study highlights the public health impact of exposure to environmental risks and the significant burden of preventable disease attributable to exposure to these four major environmental risk factors in South Africa. Evidence-based policies and programs must be developed and implemented to address these risk factors at individual, household, and community levels.
Resumo:
Previous attempts to determine the degree to which exposure to environmental factors contribute to noncommunicable diseases (NCDs) have been very conservative and have significantly underestimated the actual contribution of the environment for at least two reasons. Firstly, most previous reports have excluded the contribution of lifestyle behavioral risk factors, but these usually involve significant exposure to environmental chemicals that increase risk of disease. Secondly, early life exposure to chemical contaminants is now clearly associated with an elevated risk of several diseases later in life, but these connections are often difficult to discern. This is especially true for asthma and neurodevelopmental conditions, but there is also a major contribution to the development of obesity and chronic diseases. Most cancers are caused by environmental exposures in genetically susceptible individuals. In addition, new information shows significant associations between cardiovascular diseases and diabetes and exposure to environmental chemicals present in air, food, and water. These relationships likely reflect the combination of epigenetic effects and gene induction. Environmental factors contribute significantly more to NCDs than previous reports have suggested. Prevention needs to shift focus from individual responsibility to societal responsibility and an understanding that effective prevention of NCDs ultimately relies on improved environmental management to reduce exposure to modifiable risks.