685 research outputs found

    Exact Geosedics and Shortest Paths on Polyhedral Surface

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    We present two algorithms for computing distances along a non-convex polyhedral surface. The ïŹrst algorithm computes exact minimal-geodesic distances and the second algorithm combines these distances to compute exact shortest-path distances along the surface. Both algorithms have been extended to compute the exact minimalgeodesic paths and shortest paths. These algorithms have been implemented and validated on surfaces for which the correct solutions are known, in order to verify the accuracy and to measure the run-time performance, which is cubic or less for each algorithm. The exact-distance computations carried out by these algorithms are feasible for large-scale surfaces containing tens of thousands of vertices, and are a necessary component of near-isometric surface ïŹ‚attening methods that accurately transform curved manifolds into ïŹ‚at representations.National Institute for Biomedical Imaging and Bioengineering (R01 EB001550

    A review on the prevention of inflammatory periimplant diseases

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    Background: An impressive number of dental implants are inserted worldwide. Evolution in dental implants and simplification of surgical techniques allowed a significant increase in the number of dentists involved in implant surgery. Most of them are general dentists, are not always sufficiently formed and experienced, frequently use low-quality implants, do not adopt the proper patient selective criteria, do not adequately monitor and maintain the inserted implants, and do not report their own statistics to the dental community. Consequently, the incidence of inflammatory periimplant diseases (IPDs) has progressively increased to values significantly higher than those previously indicated by the scientific literature. Materials and Methods: Two main literature searches were undertaken in October 2018 in the PubMed Website database. Only articles written in English and published from 2008 onward were considered; 'Clinical Trial,' 'Meta analysis,' 'Observational study,' 'Review,' and 'Validation study' were selected as article type filters. The following keywords were used in the searches: 'Peri implantitis prevention' and 'Dental implant failure prevention.'Results: Preventive measures are analyzed according to the different factors that can favor the occurrence of an infection. The factors are divided into (i) implant dependent, (ii) patient dependent, and (iii) surgeon dependent. Conclusions: Scientific and clinical data confirm that when materials are selected with care, patients are carefully evaluated for factors of risk and attitude to adhere to the necessary maintenance program, and operative protocols and maintenance programs are respected dental implants can be attractive and effective tools for oral rehabilitation. Nevertheless, dentists and patients should have greater awareness that in many cases the decision to utilize dental implants cannot be taken lightly

    The Supply Of Community Supported Agriculture

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    Community Supported Agriculture (CSA) has undergone both a rapid increase in growth and interest over the last two decades.  As such, the amount of literature on the subject has also increased.  However, there are few, if any, theoretical models of supply for CSA memberships (shares) that have been developed from CSA farm data.  This paper uses both survey and anecdotal data from the Roxbury Biodynamic Farm, one of the largest CSA in the United States, to present a theory of supply for CSA membership.  Included in the discussion is the consideration that CSA farms are not profit maximizing and that the farmers (i.e. the suppliers) knowingly take on the responsibilities and earnings associated with a CSA

    The Demand For Community Supported Agriculture

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    Community Supported Agriculture (CSA) has undergone both a rapid increase in growth and interest over the last decade.  As such, the amount of literature on the subject has also increased.  However, there are few, if any, theoretical models of demand on CSA that have been developed from membership data. This paper uses both survey and anecdotal data of members of the Roxbury Biodynamic Farm, the second largest CSA in the United States, to present a theory of demand for CSA membership. Included in the discussion is consideration of the evidence that there is a direct relationship between production method and demand, usually a shibboleth in traditional economic analysis. Further exploration considers the possibility that over time participation influences the very nature of demand for CSA membership, and hypothesizes that this dynamic demand is a necessary but insufficient condition for the sustainability of CSA

    Agent-Based Simulation of urban goods distribution. A literature review

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    Agent-based simulation (ABS) appears to be a suitable tool for research and application in the field of city logistics. In this paper, an attempt was made to classify the current literature on ABS in urban freight distribution following some homogeneity criteria. A set of six criteria was adopted and relevant papers were classified accordingly. It emerges that agent-based simulation models are suitable for use in simulating urban freight distribution, identifying a set of agents (at most, one agent per stakeholder) that operate to achieve their objectives, following rules, interacting, and learning from experience. However, this approach is still to be fully developed: the applications provided in the literature are only for test cases, refer to small study areas and a limited number of agents

    Underuse of oral anticoagulants in patients with nonvalvular atrial fibrillation in Italy

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    INTRODUCTION: Oral anticoagulants (OAs) are significantly more effective than Aspirin in the prevention of cerebrovascular accidents among patients with atrial fibrillation (AF). Several studies, however, showed OAs to be widely underused in these patients. OBJECTIVE: To assess the appropriateness of antithrombotic therapy in an Italian population of AF patients. METHODS: Two hundred and fifty-five consecutive patients affected by nonvalvular AF participated in the study. Data were collected on demographic characteristics, risk factors for stroke, current prophylactic therapy, and perceived or actual risk factors for bleeding. INR levels were measured. Patients were stratified by their risk for stroke (214 at high risk, 21 moderate, 20 low), and their prophylactic therapy was analysed in light of international antithrombotic therapy recommendations. After therapy adjustment, 203 of our patients were followed-up for the occurrence of cerebrovascular events for an average of 27 months. RESULTS: Upon admission, 35% (n=75) of patients in the high-risk category were either taking no antithrombotic prophylaxis or were being treated with Aspirin. In addition, 38 of 139 patients receiving OAs had an INR<2. Thus, a total of 113 (52.8%) high-risk subjects were not receiving adequate antithrombotic therapy. Of high-risk patients not treated with OAs, 46.7% reported no perceived or actual risk factors for bleeding. The annual incidence of cerebrovascular accidents was 3.8% among 163 high-risk patients assigned to OA treatment, and 4.5% among 39 patients given Aspirin treatment. Relative to expected annual incidence rates, cerebrovascular risk in anticoagulated patients was reduced by about 70%. CONCLUSIONS: Underuse of OAs is still common in Italy, and much of it cannot be explained by the concern for haemorrhage. Support and training in the complex task of anticoagulation management may help to extend this efficacious prophylactic therapy to all patients who may benefit from it

    Multi-Area Visuotopic Map Complexes in Macaque Striate and Extra-striate Cortex

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    We propose that a simple, closed-form mathematical expression--the Wedge-Dipole mapping--provides a concise approximation to the full-field, two-dimensional topographic structure of macaque V1, V2, and V3. A single map function, which we term a map complex, acts as a simultaneous descriptor of all three areas. Quantitative estimation of the Wedge-Dipole parameters is provided via 2DG data of central-field V1 topography and a publicly available data set of full-field macaque V1 and V2 topography. Good quantitative agreement is obtained between the data and the model presented here. The increasing importance of fMRI-based brain imaging motivates the development of more sophisticated two-dimensional models of cortical visuotopy, in contrast to the one-dimensional approximations that have been in common use. One reason is that topography has traditionally supplied an important aspect of "ground truth", or validation, for brain imaging, suggesting that further development of high-resolution fMRI will be facilitated by this data analysis. In addition, several important insights into the nature of cortical topography follows from this work. The presence of anisotropy in cortical magnification factor is shown to follow mathematically from the shared boundary conditions at the V1-V2 and V2-V3 borders, and therefore may not causally follow from the existence of columnar systems in these areas, as is widely assumed. An application of the Wedge-Dipole model to localizing aspects of visual processing to specific cortical areas--extending previous work in correlating V1 cortical magnification factor to retinal anatomy or visual psychophysics data--is briefly discussed.National Institute of Health/National Institute of Biomedical Imaging and Bioengineering (R01 EB001550

    Lesch-Nyhan syndrome: evaluation of a modified bite device to prevent bite injuries

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    Lesch-Nyhan syndrome (LNS) is a serious form of hypoxanthine-guanine phosphoribosyltransferase (HPRT) deficiency, a hereditary purinemetabolismdisorder. The prevalence reported in the literature is 1/380,000 to 235,000 births. Males are affected and females are heterozygous carriers. LNS patients present a combination of hypotonia, spasticity, and neurological and behavioral disorders. They also show an obsessive-compulsive self-injurious behavior with bites and injuries to the lips, tongue, cheeks and fingers. The literature offers little scientific contribution related to the management of this problem. The authors describe their experience with a 4-year-old LNS patient and present a viable solution to control and avoid bite injuries, namely a specifically modified bite. The patient was treated at the Pediatric Dentistry Department of "Sapienza" University of Rome with a modified bite with the internal surface, in contact with the teeth, realized in 2-mm-thick soft silicone, and the exterior part consisting of a transparent resin shell with front and rear shields to separate lips and cheeks from the dental arches. At a 12-month follow-up visit, compliance was excellent: the child wore the device with regularity and without discomfort, even during soft-food feeding. No intraoral bite injuries were found, with a general improvement of the young patient's quality of life

    Freight distribution with electric vehicles: A case study in Sicily. RES, infrastructures and vehicle routing

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    Abstract This paper deals with the issue of the production of electricity required for an electric delivery van to carry out its daily mission. In particular, the technical solutions adopted for the generation and management of energy from renewable energy sources will be illustrated. Subsequently a vehicle routing problem with time windows is formulated in order to optimize the freight distribution at urban level completing the exploration of two aspects, infrastructures and management of the service, considered fundamental for dealing with the distribution of freight in a system scenario. The article describes a case study for the delivery of freight within the last mile in which the installation of renewable energy production plants is proposed in the same place where the urban distribution center has been planned. The area dedicated to freight handling is thus proposed in the work as an energy platform as well as logistics. The optimization of a freight delivery service is performed in order to reduce the energy used by the vehicle in its daily travels and some aspects related to the governance (i.e. time windows allowed for the delivery/pick-up operations) are included in the problem constraints. A test application, considering a set of 84 retailers, has been carried out as case study in the Capo d'Orlando municipality (Sicily, Italy)

    Intersubject Regularity in the Intrinsic Shape of Human V1

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    Previous studies have reported considerable intersubject variability in the three-dimensional geometry of the human primary visual cortex (V1). Here we demonstrate that much of this variability is due to extrinsic geometric features of the cortical folds, and that the intrinsic shape of V1 is similar across individuals. V1 was imaged in ten ex vivo human hemispheres using high-resolution (200 ÎŒm) structural magnetic resonance imaging at high field strength (7 T). Manual tracings of the stria of Gennari were used to construct a surface representation, which was computationally flattened into the plane with minimal metric distortion. The instrinsic shape of V1 was determined from the boundary of the planar representation of the stria. An ellipse provided a simple parametric shape model that was a good approximation to the boundary of flattened V1. The aspect ration of the best-fitting ellipse was found to be consistent across subject, with a mean of 1.85 and standard deviation of 0.12. Optimal rigid alignment of size-normalized V1 produced greater overlap than that achieved by previous studies using different registration methods. A shape analysis of published macaque data indicated that the intrinsic shape of macaque V1 is also stereotyped, and similar to the human V1 shape. Previoud measurements of the functional boundary of V1 in human and macaque are in close agreement with these results
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