974 resultados para Subset Sum Problem


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This factsheet describes voice disorders such as 'hoarseness' in children and what parents can do to help their child with a voice problem.

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Activated CD8 T cells develop cytotoxicity against autologous cells bearing foreign Ags and self/tumor Ags. However, self-specific cytolysis needs to be kept under control to avoid overwhelming immunopathology. After peptide vaccination of melanoma patients, we studied molecular and functional properties of T cell subsets specific for the self/tumor Ag Melan-A/MART-1. Ex vivo analysis revealed three Ag-specific effector memory (EM) populations, as follows: CD28-negative EM (EM28(-)) T cells strongly expressing granzyme/perforin, and two EM28(+) subsets, one with high and the other with low level expression of these cytotoxic proteins. For further functional characterization, we generated 117 stable CD8 T cell clones by ex vivo flow cytometry-based sorting of these subsets. All EM28(-)-derived clones lysed target cells with high efficacy. In contrast, EM28(+)-derived clones were heterogenous, and could be classified in two groups, one with high and the other with low killing capacity, correlating with granzyme/perforin expression. High and low killer phenotypes remained surprisingly stable for several months. However, strongly increased granzyme expression and cytotoxicity were observed after exposure to IL-12. Thus, the data reveal a newly identified subset of CD28(+) conditional killer T cells. Because CD28 can mediate strong costimulatory signals, tight cytotoxicity control, as shown in this study through IL-12, may be particularly important for subsets of T cells expressing CD28.

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Improvement of nerve regeneration and functional recovery following nerve injury is a challenging problem in clinical research. We have already shown that following rat sciatic nerve transection, the local administration of triiodothyronine (T3) significantly increased the number and the myelination of regenerated axons. Functional recovery is a sum of the number of regenerated axons and reinnervation of denervated peripheral targets. In the present study, we investigated whether the increased number of regenerated axons by T3-treatment is linked to improved reinnervation of hind limb muscles. After transection of rat sciatic nerves, silicone or biodegradable nerve guides were implanted and filled with either T3 or phosphate buffer solution (PBS). Neuromuscular junctions (NMJs) were analyzed on gastrocnemius and plantar muscle sections stained with rhodamine alpha-bungarotoxin and neurofilament antibody. Four weeks after surgery, most end-plates (EPs) of operated limbs were still denervated and no effect of T3 on muscle reinnervation was detected at this stage of nerve repair. In contrast, after 14 weeks of nerve regeneration, T3 clearly enhanced the reinnervation of gastrocnemius and plantar EPs, demonstrated by significantly higher recovery of size and shape complexity of reinnervated EPs and also by increased acetylcholine receptor (AChRs) density on post synaptic membranes compared to PBS-treated EPs. The stimulating effect of T3 on EP reinnervation is confirmed by a higher index of compound muscle action potentials recorded in gastrocnemius muscles. In conclusion, our results provide for the first time strong evidence that T3 enhances the restoration of NMJ structure and improves synaptic transmission.

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Self-organizing maps (Kohonen 1997) is a type of artificial neural network developedto explore patterns in high-dimensional multivariate data. The conventional versionof the algorithm involves the use of Euclidean metric in the process of adaptation ofthe model vectors, thus rendering in theory a whole methodology incompatible withnon-Euclidean geometries.In this contribution we explore the two main aspects of the problem:1. Whether the conventional approach using Euclidean metric can shed valid resultswith compositional data.2. If a modification of the conventional approach replacing vectorial sum and scalarmultiplication by the canonical operators in the simplex (i.e. perturbation andpowering) can converge to an adequate solution.Preliminary tests showed that both methodologies can be used on compositional data.However, the modified version of the algorithm performs poorer than the conventionalversion, in particular, when the data is pathological. Moreover, the conventional ap-proach converges faster to a solution, when data is \well-behaved".Key words: Self Organizing Map; Artificial Neural networks; Compositional data

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This paper shows how instructors can use the problem‐based learning method to introduce producer theory and market structure in intermediate microeconomics courses. The paper proposes a framework where different decision problems are presented to students, who are asked to imagine that they are the managers of a firm who need to solve a problem in a particular business setting. In this setting, the instructors’ role isto provide both guidance to facilitate student learning and content knowledge on a just‐in‐time basis

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We shall call an n × p data matrix fully-compositional if the rows sum to a constant, and sub-compositional if the variables are a subset of a fully-compositional data set1. Such data occur widely in archaeometry, where it is common to determine the chemical composition of ceramic, glass, metal or other artefacts using techniques such as neutron activation analysis (NAA), inductively coupled plasma spectroscopy (ICPS), X-ray fluorescence analysis (XRF) etc. Interest often centres on whether there are distinct chemical groups within the data and whether, for example, these can be associated with different origins or manufacturing technologies

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Background The 'database search problem', that is, the strengthening of a case - in terms of probative value - against an individual who is found as a result of a database search, has been approached during the last two decades with substantial mathematical analyses, accompanied by lively debate and centrally opposing conclusions. This represents a challenging obstacle in teaching but also hinders a balanced and coherent discussion of the topic within the wider scientific and legal community. This paper revisits and tracks the associated mathematical analyses in terms of Bayesian networks. Their derivation and discussion for capturing probabilistic arguments that explain the database search problem are outlined in detail. The resulting Bayesian networks offer a distinct view on the main debated issues, along with further clarity. Methods As a general framework for representing and analyzing formal arguments in probabilistic reasoning about uncertain target propositions (that is, whether or not a given individual is the source of a crime stain), this paper relies on graphical probability models, in particular, Bayesian networks. This graphical probability modeling approach is used to capture, within a single model, a series of key variables, such as the number of individuals in a database, the size of the population of potential crime stain sources, and the rarity of the corresponding analytical characteristics in a relevant population. Results This paper demonstrates the feasibility of deriving Bayesian network structures for analyzing, representing, and tracking the database search problem. The output of the proposed models can be shown to agree with existing but exclusively formulaic approaches. Conclusions The proposed Bayesian networks allow one to capture and analyze the currently most well-supported but reputedly counter-intuitive and difficult solution to the database search problem in a way that goes beyond the traditional, purely formulaic expressions. The method's graphical environment, along with its computational and probabilistic architectures, represents a rich package that offers analysts and discussants with additional modes of interaction, concise representation, and coherent communication.

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The statistical analysis of literary style is the part of stylometry that compares measurable characteristicsin a text that are rarely controlled by the author, with those in other texts. When thegoal is to settle authorship questions, these characteristics should relate to the author’s style andnot to the genre, epoch or editor, and they should be such that their variation between authors islarger than the variation within comparable texts from the same author.For an overview of the literature on stylometry and some of the techniques involved, see for exampleMosteller and Wallace (1964, 82), Herdan (1964), Morton (1978), Holmes (1985), Oakes (1998) orLebart, Salem and Berry (1998).Tirant lo Blanc, a chivalry book, is the main work in catalan literature and it was hailed to be“the best book of its kind in the world” by Cervantes in Don Quixote. Considered by writterslike Vargas Llosa or Damaso Alonso to be the first modern novel in Europe, it has been translatedseveral times into Spanish, Italian and French, with modern English translations by Rosenthal(1996) and La Fontaine (1993). The main body of this book was written between 1460 and 1465,but it was not printed until 1490.There is an intense and long lasting debate around its authorship sprouting from its first edition,where its introduction states that the whole book is the work of Martorell (1413?-1468), while atthe end it is stated that the last one fourth of the book is by Galba (?-1490), after the death ofMartorell. Some of the authors that support the theory of single authorship are Riquer (1990),Chiner (1993) and Badia (1993), while some of those supporting the double authorship are Riquer(1947), Coromines (1956) and Ferrando (1995). For an overview of this debate, see Riquer (1990).Neither of the two candidate authors left any text comparable to the one under study, and thereforediscriminant analysis can not be used to help classify chapters by author. By using sample textsencompassing about ten percent of the book, and looking at word length and at the use of 44conjunctions, prepositions and articles, Ginebra and Cabos (1998) detect heterogeneities that mightindicate the existence of two authors. By analyzing the diversity of the vocabulary, Riba andGinebra (2000) estimates that stylistic boundary to be near chapter 383.Following the lead of the extensive literature, this paper looks into word length, the use of the mostfrequent words and into the use of vowels in each chapter of the book. Given that the featuresselected are categorical, that leads to three contingency tables of ordered rows and therefore tothree sequences of multinomial observations.Section 2 explores these sequences graphically, observing a clear shift in their distribution. Section 3describes the problem of the estimation of a suden change-point in those sequences, in the followingsections we propose various ways to estimate change-points in multinomial sequences; the methodin section 4 involves fitting models for polytomous data, the one in Section 5 fits gamma modelsonto the sequence of Chi-square distances between each row profiles and the average profile, theone in Section 6 fits models onto the sequence of values taken by the first component of thecorrespondence analysis as well as onto sequences of other summary measures like the averageword length. In Section 7 we fit models onto the marginal binomial sequences to identify thefeatures that distinguish the chapters before and after that boundary. Most methods rely heavilyon the use of generalized linear models

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Epipolar geometry is a key point in computer vision and the fundamental matrix estimation is the only way to compute it. This article surveys several methods of fundamental matrix estimation which have been classified into linear methods, iterative methods and robust methods. All of these methods have been programmed and their accuracy analysed using real images. A summary, accompanied with experimental results, is given

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Introduction The Andalusian Public Health System Virtual Library (Biblioteca Virtual del Sistema Sanitario Público de Andalucía, BV-SSPA) was set up in June 2006. It consists of a regional government action with the aim of democratizing the health professional access to quality scientific information, regardless of the professional workplace. Andalusia is a region with more than 8 million inhabitants, with 100,000 health professionals for 41 hospitals, 1,500 primary healthcare centres, and 28 centres for non-medical attention purposes (research, management, and educational centres). Objectives The Department of Development, Research and Investigation (R+D+i) of the Andalusian Regional Government has, among its duties, the task of evaluating the hospitals and centres of the Andalusian Public Health System (SSPA) in order to distribute its funding. Among the criteria used is the evaluation of the scientific output, which is measured using bibliometry. It is well-known that the bibliometry has a series of limitations and problems that should be taken into account, especially when it is used for non-information sciences, such us career, funding, etc. A few years ago, the bibliometric reports were done separately in each centre, but without using preset and well-defined criteria, elements which are basic when we need to compare the results of the reports. It was possible to find some hospitals which were including Meeting Abstracts in their figures, while others do not, and the same was happening with Erratum and many other differences. Therefore, the main problem that the Department of R+D+i had to deal with, when they were evaluating the health system, was that bibliometric data was not accurate and reports were not comparable. With the aim of having an unified criteria for the whole system, the Department of R+D+i ordered the BV-SSPA to do the year analysis of the scientific output of the system, using some well defined criteria and indicators, among whichstands out the Impact Factor. Materials and Methods As the Impact Factor is the bibliometric indicator that the virtual library is asked to consider, it is necessary to use the database Web of Science (WoS), since it is its owner and editor. The WoS includes the databases Science Citation Index (SCI), Social Sciences Citation Index (SSCI) and Arts & Humanities Citation Index. To gather all the documents, SCI and SSCI are used; to obtain the Impact Factor and quartils, it is used the Journal Citation Reports, JCR. Unlike other bibliographic databases, such us MEDLINE, the bibliometric database WoS includes the address of all the authors. In order to retrieve all the scientific output of the SSPA, we have done general searches, which are afterwards processed by a tool developed by our library. We have done nine different searches using the field ‘address’; eight of them including ‘Spain’ and each one of the eight Andalusian Regions, and the other one combining ‘Spain’ with all those cities where there are health centres, since we have detected that there are some authors that do not use the region in their signatures. These are some of the search strategies: AD=Malaga and AD=Spain AD=Sevill* and AD=Spain AD=SPAIN AND (AD=GUADIX OR AD=BAZA OR AD=MOTRIL) Further more, the field ‘year’ is used to determine the period. To exploit the data, the BV-SSPA has developed a tool called Impactia. It is a web application which uses a database to store the information of the documents generated by the SSPA. Impactia allows the user to automatically process the retrieved documents, assigning them to their correspondent centres. In order to do the classification of documents automaticaly, it was necessary to detect the huge variability of names of the centres that the authors use in their signatures. Therefore, Impactia knows that if an author signs as “Hospital Universitario Virgen Macarena”, “HVM” or “Hosp. Virgin Macarena”, he belongs to the same centre. The figure attached shows the variability found for the Empresa Publica Hospital de Poniente. Besides the documents from WoS, Impactia includes the documents indexed in Scopus and in other databases, where we do bibliographic searches using similar strategies to the later ones. Aware that in the health centres and hospitals there is a lot of grey literature that is not gathered in databases, Impactia allows the centres to feed the application with these documents, so that all the SSPA scientific output is gathered and organised in a centralized place. The ones responsible of localizing this gray literature are the librarians of each one of the centres. They can also do statements to the documents and indicators that are collected and calculated by Impactia. The bulk upload of documents from WoS and Scopus into Impactia is monthly done. One of the main issues that we found during the development of Impactia was the need of dealing with duplicated documents obtained from different sources. Taking into account that sometimes titles might be written differently, with slashes, comas, and so on, Impactia detects the duplicates using the field ‘DOI’ if it is available or comparing the fields: page start, page end and ISSN. Therefore it is possible to guarantee the absence of duplicates. Results The data gathered in Impactia becomes available to the administrative teams and hospitals managers, through an easy web page that allows them to know at any moment, and with just one click, the detailed information of the scientific output of their hospitals, including useful graphs such as percentage of document types, journals where their scientists usually publish, annual comparatives, bibliometric indicators and so on. They can also compare the different centres of the SSPA. Impactia allows the user to download the data from the application, so that he can work with this information or include them in their centres’ reports. This application saves the health system many working hours. It was previously done manually by forty one librarians, while now it is done by only one person in the BV-SSPA during two days a month. To sum up, the benefits of Impactia are: It has shown its effectiveness in the automatic classification, treatment and analysis of the data. It has become an essential tool for all managers to evaluate quickly and easily the scientific production of their centers. It optimizes the human resources of the SSPA, saving time and money. It is the reference point for the Department of R+D+i to do the scientific health staff evaluation.