535 research outputs found

    A comparative analysis of the hominin triquetrum (SKX 3498) from Swartkrans, South Africa

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    The SKX 3498 triquetrum from Member 2 at Swartkrans Cave, South Africa is the only hominin triquetrum uncovered (and published) thus far from the early Pleistocene hominin fossil record. Although SKX 3498 was found over two decades ago, its morphology has not been formally described or analysed, apart from the initial description. Furthermore, the taxonomic attribution of this fossil remains ambiguous as both Paranthropus and early Homo have been identified at Swartkrans. This analysis provides the first quantitative analysis of the SKX 3498 triquetrum, in comparison to those of extant hominids (humans and other great apes) and other fossil hominins. Although the initial description of the SKX 3498 triquetrum summarised the morphology as generally human-like, this analysis reveals that quantitatively it is often similar to the triquetra of all hominine taxa and not necessarily humans in particular. Shared hominid-like morphology between SKX 3498 and Neanderthals suggests that both may retain the symplesiomorphic hominin form, but that functional differences compared to modern humans may be subtle. Without knowledge of triquetrum morphology typical of earlier Pliocene hominins, the taxonomic affiliation of SKX 3498 remains unclear

    Quantum group covariant (anti)symmetrizers, epsilon-tensors, vielbein, Hodge map and Laplacian

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    GL_q(N)- and SO_q(N)-covariant deformations of the completely symmetric/antisymmetric projectors with an arbitrary number of indices are explicitly constructed as polynomials in the braid matrices. The precise relation between the completely antisymmetric projectors and the completely antisymmetric tensor is determined. Adopting the GL_q(N)- and SO_q(N)-covariant differential calculi on the corresponding quantum group covariant noncommutative spaces C_q^N, R_q^N, we introduce a generalized notion of vielbein basis (or "frame"), based on differential-operator-valued 1-forms. We then give a thorough definition of a SO_q(N)-covariant R_q^N-bilinear Hodge map acting on the bimodule of differential forms on R_q^N, introduce the exterior coderivative and show that the Laplacian acts on differential forms exactly as in the undeformed case, namely it acts on each component as it does on functions.Comment: latex file, 24 pages. Some citations added and misprints corrected. Final version to appear in J. Phys. A Math. and Ge

    An exploration of defensive pessimism, explanatory style, and expectations in relation to the academic performance of college and university students.

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    Researchers have studied the concepts of optimism and pessimism as traits, expectations, strategies, and styles of explaining outcomes. Explanatory style and the strategy of defensive pessimism are two of these areas. In general, optimistic explanatory style has been associated with better outcomes including academic performance. Some studies have found that pessimistic explanatory style has been associated with better academic outcomes. One suggestion in the literature was that defensive pessimism might explain the cases where pessimistic explanatory style is associated with better academic outcomes. To evaluate this explanation, the Academic Attributional Style Questionnaire (AASQ, Revised Defensive Pessimism Questionnaire (DPQ), and Brief Symptom Inventory (BSI) were administered to 188 undergraduate and graduate students from five colleges and universities. Measures of academic achievement included official course and exam grade as reported by the instructor as well as self-reported GPA. There were no differences in academic performance between groups that made more pessimistic explanations and those who made more optimistic explanations. There were no differences within the group of those with more pessimistic explanatory styles regardless of level of use of defensive pessimism. Explanatory style was associated with expectations for course grade. There were no differences on outcome expectations or efficacy between defensive pessimists and low exam scorers. Defensive pessimism was associated with multiple psychological symptoms as measured by the Brief Symptom Inventory (BSI). Further investigation to determine if encouraging a strategy defensive pessimism in those with more pessimistic explanatory styles would lead to improved performance. More research needs to be devoted to the study of the relationships among explanatory style, defensive pessimism, and expectations

    Value of Time for Commercial Vehicle Operators

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    The spring load restriction policy of Minnesota has been in effect for over 50 years with little consideration given to the cost that it imposes on the freight industry. A cost-benefit study was recently commissioned to examine the policy. The cost-benefit analysis required a precise estimate of the value of time for commercial vehicle operators in Minnesota. An estimate was not available from previous studies, or from previous data. The necessary revealed preference (RP) information does not exist, and relevance of previous studies was questioned based on the differences in geographic location and the age of data used to construct the estimates. A sample was constructed from several trucking industry sources to conduct a survey. Interviews were conducted using an adaptive stated preference (ASP) survey to derive an estimate to the nearest dollar. A tobit model was fit to the data from the interviews to derive the estimate for value of time. A mean of 49.42wasfound,witha95percentconfidenceintervalfrom49.42 was found, with a 95 percent confidence interval from 40.45 to $58.39. Variation in the distribution of values is largely undetermined, with the exception of fleet operation, whether it is a for-hire truck fleet, or a private truck fleet. .

    Bolton's index efficacy with manual vs digital measurements

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    ABSTRACTObjectiveTo assess whether there is a variation in the values of Bolton index, making measurements manually or digitally.Material and methods70 pairs of study models were analyzed and measured on two occasions: one using a compass and a millimeter rule, and the other using an electronic vernier.ResultsNo statistically significant difference was found between the two measurements.ConclusionBoth ways to perform mesiodistal dental measurements are good choices for Bolton analysis

    Learning from Positive and Unlabeled Examples

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    International audienceIn many machine learning settings, labeled examples are difficult to collect while unlabeled data are abundant. Also, for some binary classification problems, positive examples, that is examples of the target class, are available. Can these additional data be used to improve accuracy of supervised learning algorithms? We investigate in this paper the design of learning algorithms from positive and unlabeled data only. Many machine learning and data mining algorithms, such as decision tree induction algorithms and naive Bayes algorithms, only use examples in order to evaluate statistical queries (SQ-like algorithms). Kearns designed the Statistical Query learning model in order to describe these algorithms. Here, we design an algorithm scheme which transforms any SQ-like algorithm into an algorithm based on positive statistical queries (estimates for probabilities over the set of positive instances) and instance statistical queries (estimates for probabilities over the instance space). We prove that any class learnable in the Statistical Query learning model is learnable from positive statistical queries and instance statistical queries only if a lower bound on the weight of any target concept ff can be estimated in polynomial time. Then, we design a decision tree induction algorithm POSC4.5, based on C4.5, that uses only positive and unlabeled examples and we give experimental results for this algorithm. The case of imbalanced classes in the sense that one of the two classes (say the positive class) is heavily underrepresented compared to the other class remains open. This problem is challenging because it is encountered in many real-world applications

    Flow termination signaling in the centralized pre-congestion notification architecture

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    Pre-congestion notification (PCN) protects inelastic traffic by using feedback on network link loads on and acting upon this accordingly. These actions comprise to admission control and termination of flows. Two PCN architectures have been defined by IETF: the centralized and decentralized PCN architecture. The decentralized PCN architecture has received much attention in the literature whereas the centralized PCN architecture has not. In the decentralized architecture, feedback is sent from the egress nodes to ingress nodes, which then take and apply decisions regarding admission of new flows and/or termination of ongoing flows. Signaling occurs only between ingress and egress nodes. In the centralized architecture these decisions are made at a central node, which requires proper signaling for action and information exchange between the central node and the egress and ingress nodes. This signaling has been suggested by other authors, but is not fully defined yet. Our contribution is twofold. We define signaling in the centralized PCN architecture focussing on flow termination, which completes the definition of the signaling in the centralized PCN architecture. Secondly, we run extensive simulations showing that the proposed signaling works well and that the performances of the centralized PCN and the decentralized PCN architectures are similar. Hence, it is expected that results from existing research on the effectiveness of decentralized PCN are also valid when the centralized PCN architecture is used
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