100,422 research outputs found
Letter, [Author unclear] to Paulina T. Merritt
No full textHandwritten letter to Paulina Merritt from an unknown author, October 1, 1876.
Fair Hitting Sequence Problem: Scheduling Activities with Varied Frequency Requirements
No full textGiven a set of n elements and a family of (possibly intersecting) subsets of V, we consider a scheduling problem of perpetual monitoring (attending) these subsets. In each time step one element of V is visited, and all sets in containing v are considered to be attended during this step. That is, we assume that it is enough to visit an arbitrary element in to attend to this whole set. Each set has an urgency factor , which indicates how frequently this set should be attended relatively to other sets. Let denote the time slot when set is attended for the i-th time. The objective is to find a perpetual schedule of visiting the elements of V, so that the maximum value is minimized. The value indicates how urgent it was to attend to set at the time slot. We call this problem the Fair Hitting Sequence (FHS) problem, as it is related to the minimum hitting set problem. In fact, the uniform FHS, when all urgency factors are equal, is equivalent to the minimum hitting set problem, implying that there is a constant such that it is NP-hard to compute -approximation schedules for FHS. We demonstrate that scheduling based on one hitting set can give poor approximation ratios, even if an optimal hitting set is used. To counter this, we design a deterministic algorithm which partitions the family into sub-families and combines hitting sets of those sub-families, giving -approximate schedules. Finally, we show an LP-based lower bound on the optimal objective value of FHS and use this bound to derive a randomized algorithm which with high probability computes -approximate schedules
Supermodular social games
Full text linkA social game is a generalization of a strategic-form game, in which not only the payoff of each player depends upon the strategies chosen by their opponents, but also their set of admissible strategies. Debreu (1952) proves the existence of a Nash equilibrium in social games with continuous strategy spaces. Recently, Polowczuk and Radzik (2004) have proposed a discrete counterpart of Debreu's theorem for two-person social games satisfying some ``convexity properties'. In this note, we define the class of supermodular social games and give an existence theorem for this class of games.Strategic-form games, social games, supermodularity, Nash equilibrium, existence.
Consistency à la Hart and Mas-Colell of efficient, linear, and symmetric values for TU-games
No full textBy Hart and Mas-Colell's axiomatization, it is known that the Shapley value for TU-games is fully characterized by its 1-standardness for two-person games and its consistency property with respect to a particular reduced game. In the framework of values for TU-games, this paper establishes a similar axiomatization for almost every value that is supposed to be efficient, linear, and symmetric (like the Shapley value). For that purpose, we introduce a general type of reduced game that takes into account the (probabilities of) two events that a removed player joins or does not join a proposed coalition in the reduced game. Similar to Hart and Mas-Colell's reduced game (in which the player joins the coalition with probability one), the general model of the reduced game involves the value itself. According to this unified approach, almost every efficient, linear, and symmetric value is consistent with respect to an appropriately chosen reduced game. The relevant reduced game varies whenever the efficient, linear, and symmetric value varies, nevertheless we present an operational criterion how to determine the appropriate reduced game (by solving an associated system of linear equations in a recursive manner). The second result states that the resulting consistency property, together with some kind of standardness for two-person games, fully characterize the given value. This paper extends the main result from a 1998 article of Driessen, Radzik and Wanink on the consistency (or reduced game) property for values that are supposed to have a weighted potential representation (since the consistency theory developed avoids the concept called a weighted potential function). Finally, the consistency theory is illustrated in the context of several known values, among which the least square values (including the Shapley value)
Supermodular Social Games
Full text linkA social game is a generalization of a strategic-form game, in which not only the payoff of each player depends upon the strategies chosen by their opponents, but also their set of admissible strategies. Debreu (1952) proves the existence of a Nash equilibrium in social games with continuous strategy spaces. Recently, Polowczuk and Radzik (2004) have proposed a discrete counterpart of Debreu's theorem for two-person social games satisfying some ''convexity properties''. In this note, we define the class of supermodular social games and give an existence theorem for this class of games.strategic-form games, social games, supermodularity, Nash equilibrium, existence
Handwritten biographical information on Paulina T. McClung Merritt
No full textA handwritten biography of Paulina T. McClung Merritt by an unknown author, 1892.
Heterogeneous and tissue-specific regulation of effector T cell responses by IFN-gamma during Plasmodium berghei ANKA infection.
Full text linkIFN-γ and T cells are both required for the development of experimental cerebral malaria during Plasmodium berghei ANKA infection. Surprisingly, however, the role of IFN-γ in shaping the effector CD4(+) and CD8(+) T cell response during this infection has not been examined in detail. To address this, we have compared the effector T cell responses in wild-type and IFN-γ(-/-) mice during P. berghei ANKA infection. The expansion of splenic CD4(+) and CD8(+) T cells during P. berghei ANKA infection was unaffected by the absence of IFN-γ, but the contraction phase of the T cell response was significantly attenuated. Splenic T cell activation and effector function were essentially normal in IFN-γ(-/-) mice; however, the migration to, and accumulation of, effector CD4(+) and CD8(+) T cells in the lung, liver, and brain was altered in IFN-γ(-/-) mice. Interestingly, activation and accumulation of T cells in various nonlymphoid organs was differently affected by lack of IFN-γ, suggesting that IFN-γ influences T cell effector function to varying levels in different anatomical locations. Importantly, control of splenic T cell numbers during P. berghei ANKA infection depended on active IFN-γ-dependent environmental signals--leading to T cell apoptosis--rather than upon intrinsic alterations in T cell programming. To our knowledge, this is the first study to fully investigate the role of IFN-γ in modulating T cell function during P. berghei ANKA infection and reveals that IFN-γ is required for efficient contraction of the pool of activated T cells
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Pelevin’s Trinity in the novel “t”: author – protagonist – reader
No full textThe article attempts to interpret Pelevin's artistic strategy in the novel "T" by exploring its subject organization and addressing the key problems of the author, the protagonist, and the reader as they are seen by the researcher. The article analyzes the peculiarities of constructing the narrative reality in the novel "T", and goes on to discuss Pelevin's philosophic models of the development of the humankind, and the emergence of his new anthropology
Measuring industry-science links through inventor-author relations: A profiling method
Full text linkIn this pilot study we examine the performance of text-based profiling in recovering a set of validated inventor-author links. In a first step we match patents and publications solely based on their similarity in content. Next, we compare inventor and author names on the highest ranked matches for the occurrence of name matches. Finally, we compare these candidate matches with the names listed in a validated set of inventor-author names. Our text-based profile methodology performs significantly better than a random matching of patents and publications, suggesting that text-based profiling is a valuable complementary tool to the name searches used in previous studies.innovation; industry-science links; text-based profiling;
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