1,702 research outputs found

    High-statistics modeling of complex pedestrian avoidance scenarios

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    Quantitatively modeling the trajectories and behavior of pedestrians walking in crowds is an outstanding fundamental challenge deeply connected with the physics of flowing active matter, from a scientific point of view, and having societal applications entailing individual safety and comfort, from an application perspective. In this contribution, we review a pedestrian dynamics modeling approach, previously proposed by the authors, aimed at reproducing some of the statistical features of pedestrian motion. Comparing with high-statistics pedestrian dynamics measurements collected in real-life conditions (from hundreds of thousands to millions of trajectories), we modeled quantitatively the statistical features of the undisturbed motion (i.e. in absence of interactions with other pedestrians) as well as the avoidance dynamics triggered by a pedestrian incoming in the opposite direction. This was accomplished through (coupled) Langevin equations with potentials including multiple preferred velocity states and preferred paths. In this chapter we review this model, discussing some of its limitations, in view of its extension toward a more complex case: the avoidance dynamics of a single pedestrian walking through a crowd that is moving in the opposite direction. We analyze some of the challenges connected to this case and present extensions to the model capable of reproducing some features of the motion

    The Probability of Default of Public Guaranteed Loans: Does the Financial intermediary Matter?

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    This paper investigates the risk of failure of loans guaranteed by public credit guarantee schemes. We analyse the determinants of the time to default of approximately 15,000 loans guaranteed by the Italian Central Guarantee Fund between 2007 and 2009. Using the Cox proportional hazards model, we test the role of the financial intermediary that requests the guarantee on a firmā€™s behalf, while distinguishing between banks and mutual guarantee institutions (MGIs) and controlling for a set of variables that characterise each guaranteed loan. The findings confirm that loans are more likely to default when a bankā€”rather than an MGIā€”is involved in the guarantee process. Considering some elements (e.g. age, size and sector) that affect opacity among small- and medium-sized enterprises (SMEs), banks seem to perform better than MGIs in screening and monitoring loans requested by firms in the manufacturing sector

    Studying oven technology towards the energy consumption optimisation for the baking process

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    A recent guideline from the European Commission declared that several highly energy consuming domestic equipment should be better regulated or avoided at all in the near future. Together with this, several EU nations are abandoning the gas ovens in favour of the electric ones, also due to the home energy rating regulations, that make impossible to get the highest rating with gas ovens. Due to this fact, the study of the technologies related to the energy efficiency in cooking is increasingly developing. The combination of several energy sources (e.g. forced convection, irradiation, microwave, etc.), as well as optimisation of each of them, is an emerging target for oven manufacturers, in matter of oven design and better use of the oven capabilities. Within this context, an energy consumption analysis and optimisation is targeted in this work, by the application of a bread baking model, validated on experimental data. Each source of energy is given the due importance and the practically applicable process solutions are compared. A basic quality standard is guaranteed by taking into account some quality markers, which are relevant on the basis of a consumer point of view. This work is a part of a more comprehensive study on oven cooking and energy integration, and could lead to practical applications in the design of energy efficient cooking programs

    Strategic Resource Allocation in the Human Brain Supports Cognitive Coordination of Object and Spatial Working Memory

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    The ability to integrate different types of information (e.g., object identity and spatial orientation) and maintain or manipulate them concurrently in working memory (WM) facilitates the flow of ongoing tasks and is essential for normal human cognition. Research shows that object and spatial information is maintained and manipulated in WM via separate pathways in the brain (object/ventral versus spatial/dorsal). How does the human brain coordinate the activity of different specialized systems to conjoin different types of information? Here we used functional magnetic resonance imaging to investigate conjunction- versus single-task manipulation of object (compute average color blend) and spatial (compute intermediate angle) information in WM. Object WM was associated with ventral (inferior frontal gyrus, occipital cortex), and spatial WM with dorsal (parietal cortex, superior frontal, and temporal sulci) regions. Conjoined object/spatial WM resulted in intermediate activity in these specialized areas, but greater activity in different prefrontal and parietal areas. Unique to our study, we found lower temporo-occipital activity and greater deactivation in temporal and medial prefrontal cortices for conjunction- versus single-tasks. Using structural equation modeling, we derived a conjunction-task connectivity model that comprises a frontoparietal network with a bidirectional DLPFC-VLPFC connection, and a direct parietal-extrastriate pathway. We suggest that these activation/deactivation patterns reflect efficient resource allocation throughout the brain and propose a new extended version of the biased competition model of WM. Hum Brain Mapp, 2011. Ā© 2010 Wiley-Liss, Inc

    Detection of Viral-like Particles by Electron Microscopy of Negatively Stained Extracts from Grapevines

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    Viral-like particles were detected by electron microscopy of negatively stained extracts from young leaves and roots of grapevines infected with fanleaf virus and purported to be infected with the graft-transmissible agents of Ieafroll, corky bark, fleck, and stem grooving. Preparations were extracted in 0.01 M phosphate buffer (pH 7.0) containing 2.5% nicotine and negatively stained with 2% ammonium molydate. Membrane associated spherical particles were detected in extracts from grapevines that tested positive for fanleaf virus by ELISA and bioassay. Similar membrane associated particles were detected in herbaceous plants inoculated with grapevine extracts. Rigid rod tobacco mosaic virus-like particles were detected in extracts from some grapevines but they were not disease associated. Flexuous rod viral-like particles about 11x800 nm with cross-banding helical substructure similar to closteroviruses were detected in extracts from leafroll infected grapevines

    A case-control study of the effectiveness of tissue plasminogen activator on 6 month patients -- reported outcomes and health care utilization

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    none5siWe examined the benefit of tissue plasminogen activator (tPA), delivered as part of usual stroke management, on patient-reported outcomes and health care utilization. Using a case control design, patients who received tPA as part of usual stroke management were compared with patients who would have received tPA had they arrived to the hospital within the therapeutic time window. Data were collected from surveys 6 months after stroke using standardized patient-reported outcome measures and questions about health care utilization. Demographic and medical data were acquired from hospital records. Patients were matched on stroke severity, age, race, and gender. Matching was done with 1:2 ratio of tPA to controls. Results were compared between groups with 1-tailed tests because of a directionally specific hypothesis in favor of the tPA group. The tPA (n = 78) and control (n = 156) groups were matched across variables, except for stroke severity, which was better in the control group; subsequent analyses controlled for this mismatch. The tPA group reported better physical function, communication, cognitive ability, depressive symptomatology, and quality of life/participation compared with the control group. Fewer people in the tPA group reported skilled nursing facility stays, emergency department visits, and rehospitalizations after their stroke compared with controls. Reports of other postacute services were not different between groups. Although it is known that tPA reduces disability, this is the first study to demonstrate the effectiveness of tPA in improving meaningful, patientreported outcomes. Thus, use of tPA provides a large benefit to the daily lives of people with ischemic stroke.mixedLang, Catherine E.; Bland, Marghuretta D.; Cheng, Nuo; Corbetta, Maurizio; Lee, Jin-MooLang, Catherine E.; Bland, Marghuretta D.; Cheng, Nuo; Corbetta, Maurizio; Lee, Jin Mo

    How good are low back pain guidelines? A critical appraisal of the quality of clinical practice guidelines using the agree II tool

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    Clinical practice guidelines (CPGs) provide evidence-based recommendations for clinical practice, but their increasing number in the last few years arises possible concerns about their quality. Preliminary results on the methodological quality of CPGs for low back pain management (LBP) are here presented. The results of this review can help researchers and Italian policymakers select and adopt the highest quality Clinical Practice Guidelines (CPGs) for Low Back Pain (LBP) management in the CPG National Systems (Sistema Nazionale Linee Guida)

    Oxygen transport and consumption in germinating seeds

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    Three mathematical models were formulated to describe the oxygen con-sumption of seeds during germination. These models were fitted to measure-ment data of oxygen consumption curves for individual germinating seeds of Savoy cabbage, barley and sugar beet provided by Fytagoras. The first model builds on a logistic growth model for the increasing population of mitochondria in the embryo during growth. The other two take the anatomy and physiologi-cal properties of the seed into account. One describes the oxygen uptake during the germination phase only. An extension of this model is capable of fitting the complete oxygen consumption curve, including the initial ā€˜repairā€™ phase in which the embryonic cells recover from their dormant state before extensive cell division and growth commences. Keywords: Modelling, seed germination, cellular respiration, oxygen transpor

    Brain mapping in a patient with congenital blindness ā€“ A case for multimodal approaches

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    Recent advances in basic neuroscience research across a wide range of methodologies have contributed significantly to our understanding of human cortical electrophysiology and functional brain imaging. Translation of this research into clinical neurosurgery has opened doors for advanced mapping of functionality that previously was prohibitively difficult, if not impossible. Here we present the case of a unique individual with congenital blindness and medically refractory epilepsy who underwent neurosurgical treatment of her seizures. Pre-operative evaluation presented the challenge of accurately and robustly mapping the cerebral cortex for an individual with a high probability of significant cortical re-organization. Additionally, a blind individual has unique priorities in one's ability to read Braille by touch and sense the environment primarily by sound than the non-vision impaired person. For these reasons we employed additional measures to map sensory, motor, speech, language, and auditory perception by employing a number of cortical electrophysiologic mapping and functional magnetic resonance imaging methods. Our data show promising results in the application of these adjunctive methods in the pre-operative mapping of otherwise difficult to localize, and highly variable, functional cortical areas
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