7,744 research outputs found

    Relationship between resistivity and specific heat in a canonical non-magnetic heavy fermion alloy system: UPt_5-xAu_x

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    UPt_(5-x)Au_x alloys form in a single crystal structure, cubic AuBe_5-type, over a wide range of concentrations from x = 0 to at least x = 2.5. All investigated alloys, with an exception for x = 2.5, were non-magnetic. Their electronic specific heat coefficient Îł\gamma varies from about 60 (x = 2) to about 700 mJ/mol K^2 (x = 1). The electrical resistivity for all alloys has a Fermi-liquid-like temperature variation, \rho = \rho_o + AT^2, in the limit of T -> 0 K. The coefficient A is strongly enhanced in the heavy-fermion regime in comparison with normal and transition metals. It changes from about 0.01 (x = 0) to over 2 micro-ohm cm/K^2 (x = 1). A/\gamma^2, which has been postulated to have a universal value for heavy-fermions, varies from about 10^-6 (x = 0, 0.5) to 10^-5 micro-ohm cm (mol K/mJ)^2 (x > 1.1), thus from a value typical of transition metals to that found for some other heavy-fermion metals. This ratio is unaffected, or only weakly affected, by chemical or crystallographic disorder. It correlates with the paramagnetic Curie-Weiss temperature of the high temperature magnetic susceptibility.Comment: 5 pages, 5 eps figures, RevTe

    New tests of the pp-wave correspondence.

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    The pp-wave/SYM correspondence is an equivalence relation, H string = Δ-J , between the hamiltonian H string of string field theory in the pp-wave background and the dilatation operator Δ in = 4 Super Yang-Mills in the double scaling limit. We calculate matrix elements of these operators in string field theory and in gauge theory. In the string theory Hilbert space we use the natural string basis, and in the gauge theory we use the basis which is isomorphic to it. States in this basis are specific linear combinations of the original BMN operators, and were constructed previously for the case of two scalar impurities. We extend this construction to incorporate BMN operators with vector and mixed impurities. This enables us to verify from the gauge theory perspective two key properties of the three-string interaction vertex of Spradlin and Volovich: (1) the vanishing of the three-string amplitude for string states with one vector and one scalar impurity; and (2) the relative minus sign in the string amplitude involving states with two vector impurities compared to that with two scalar impurities. This implies a spontaneous breaking of the 2 symmetry of the string field theory in the pp-wave background. Furthermore, we calculate the gauge theory matrix elements of Δ-J for states with an arbitrary number of scalar impurities. In all cases we find perfect agreement with the corresponding string amplitudes derived from the three-string vertex

    6500 BP Oldsquaw Duck (Clangula hyemalis) from Northern Ellesmere Island, Arctic Archipelago, Canada

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    A nearly complete skeleton, including partially preserved feathers, of an Oldsquaw duck (Clangula hyemalis L.) was recovered from Holocene marine deposits in Clements Markham Inlet, Ellesmere Island, N.W.T., Canada. The specimen was 2 m lower in the section than allochthonous terrestrial plants previously dated at 6400 ± BP (Sl-4314) and is estimated to be 6500 years old. These deposits represent a marine, prodeltaic sedimentary environment that emerged from the fiord as the result of postglacial isostatic uplift. Comparison of the specimen's present elevation and age with the inlet's emergence curve indicates the duck was buried in a paleowater depth of 38 m. Isostatic uplift is ubiquitous in the Canadian Arctic, exposing ocean bottoms and prodeltas. The deposits from these environments deserve closer scrutiny for fossils by Quaternary scientists, as they can contribute to a better understanding of the biologic development of the Canadian Arctic.

    The Effect of Trait and State Disgust on Fear of God and Sin

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    There is a growing literature suggesting disgust plays a major role in religiosity. However, the relationships between specific domains of disgust sensitivity and general religious fundamentalism or religious scrupulosity remains unknown and a lack of experimental data prevents the drawing of causal inferences about the potential effects of disgust on religiosity. Two studies are reported that examined the relationship between specific types of disgust sensitivity (i.e., pathogen, sexual, and moral disgust) and specific religious beliefs (i.e., fear of sin and fear of God). In the first study it was found that sexual disgust and pathogen disgust were significantly correlated with fear of sin and fear of God, respectively. In the second study the experimental induction of disgust led to greater fear of sin but not to the fear of God. These findings suggest that pathogen and sexual disgust sensitivities may serve as effective mechanisms for inflated scrupulosity. Taken together the outcomes from both studies converge on a greater understanding of the 'Human Behavioral Immune System' model that can account for social behavior with the evolution of adaptive benefit and perhaps more importantly highlights the possible drivers of specific religious behavior

    Megafirms

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    This paper documents and explains the amazing growth of the largest firms in law, accounting, and investment banking. Scholars to date have used various supply-side theories to explain the growth, and have generally examined only one industry at a time. We give the first demand-side explanation of firm growth, and show how the explanation is similar for firms in all project industries. We show that law plays an important role in determining industry structure. Among the areas we cover are the growth of Multi-Disciplinary Practice firms. We argue that the issues surrounding MDPs can best be understood by looking more broadly at the forces driving project industries. We also explain the driving forces behind the breakup of the Big Five accounting firms, the consolidation of the investment banking industry and the heretofore unexamined divergent growth patterns of the law firms in the plaintiffs\u27 securities litigation field

    The ultra‐cold polarized hydrogen jet project

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    Research is described on a jet of polarized atomic hydrogen. Atoms in the two lower hyperfine states are trapped at 0.4 k in a 5 T magnetic field. Microwaves at 140 GHz then drive transitions to the upper hyperfine states and these atoms are expelled from the field to form the beam. Atoms have been trapped, transitions driven, and atoms detected outside the trapping field, but preliminary measurements are not fully understood. Studies are continuing.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87383/2/1311_1.pd

    Phytoplankton dynamics from the Cambrian Explosion to the onset of the Great Ordovician Biodiversification Event: a review of Cambrian acritarch diversity

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    Most early Palaeozoic acritarchs are thought to represent a part of the marine phytoplankton and so constituted a significant element at the base of the marine trophic chain during the ‘Cambrian Explosion’ and the subsequent ‘Great Ordovician Biodiversification Event.’ Cambrian acritarch occurrences have been recorded in a great number of studies. In this paper, published data on Cambrian acritarchs are assembled in order to reconstruct taxonomic diversity trends that can be compared with the biodiversity of marine invertebrates. We compile a database and calculate various diversity indices at global and regional (i.e. Gondwana or Baltica) scales. The stratigraphic bins applied are at the level of the ten Cambrian stages, or of fourteen commonly used biozones in a somewhat higher resolved scheme. Our results show marked differences between palaeogeographical regions. They also indicate limitations of the data and a potential sampling bias, as the taxonomic diversity indices of species are significantly correlated with the number of studies per stratigraphic bin. The total and normalized diversities of genera are not affected in the same way. The normalized genus diversity curves show a slow but irregular rise over the course of the Cambrian. These also are the least biased. A radiation of species and to a lesser extent of genera in the ‘lower’ Cambrian Series 2 appears to mirror the ‘Cambrian Explosion’ of metazoans. This radiation, not evident on Gondwana, is followed by a prominent low in species diversity in the upper Series 3 and lower Furongian. Highest diversities are reached globally, and on both Baltica and Gondwana, in the uppermost Cambrian Stage 10, more precisely in the Peltura trilobite Zone, preceding a substantial phase of acritarch species extinction below and at the Cambrian/Ordovician boundary. Nearly all the genera present in Stage 10 survived into the Ordovician. The forms that emerged during the Cambrian therefore became the foundation for the more rapid radiation of acritarchs during the ‘Great Ordovician Biodiversification Event’

    Current Fertility Status Does Not Predict Sociosexual Attitudes and Desires in Normally Ovulating Women

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    Previous research has found that women at peak fertility show greater interest in extra-pair sex. However, recent replications have failed to detect this effect. In this study, we add to this ongoing debate by testing whether sociosexuality (the willingness to have sex in the absence of commitment) is higher in women who are at peak fertility. A sample of normally ovulating women (N = 773) completed a measure of sociosexuality and had their current fertility status estimated using the backward counting method. Contrary to our hypothesis, current fertility was unrelated to sociosexual attitudes and desires, even when relationship status was included as a moderator. These findings raise further doubts about the association between fertility and desire for extra-pair sex
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