419 research outputs found

    How the toughness in metallic glasses depends on topological and chemical heterogeneity

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    To gain insight into the large toughness variability observed between metallic glasses (MGs), we examine the origin of fracture toughness through bending experiments and molecular dynamics (MD) simulations for two binary MGs: Pd_(82)Si_(18) and Cu_(46)Zr_(54). The bending experiments show that Pd_(82)Si_(18) is considerably tougher than Cu_(46)Zr_(54), and the higher toughness of Pd_(82)Si_(18) is attributed to an ability to deform plastically in the absence of crack nucleation through cavitation. The MD simulations study the initial stages of cavitation in both materials and extract the critical factors controlling cavitation. We find that for the tougher Pd_(82)Si_(18), cavitation is governed by chemical inhomogeneity in addition to topological structures. In contrast, no such chemical correlations are observed in the more brittle Cu_(46)Zr_(54), where topological low coordination number polyhedra are still observed around the critical cavity. As such, chemical inhomogeneity leads to more difficult cavitation initiation in Pd_(82)Si_(18) than in Cu_(46)Zr_(54), leading to a higher toughness. The absence of chemical separation during cavitation initiation in Cu_(46)Zr_(54) decreases the energy barrier for a cavitation event, leading to lower toughness

    Международная трудовая миграция и нелегальная миграция в России

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    Огляд монографії: Метелев С.Е. Международная трудовая миграция и нелегальная миграция в России. Монография. – М.: Юнити. – 2006. – 175 с

    The 4^4He(e,ep)(e,e'p) Cross Section at Large Missing Energy

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    The (e,ep)(e,e'p) reaction on 4He^{4}{He} nuclei was studied in kinematics designed to emphasize effects of nuclear short-range correlations. The measured cross sections display a peak in the kinematical regions where two-nucleon processes are expected to dominate. Theoretical models incorporating short-range correlation effects agree reasonably with the data.Comment: 4 pages LaTeX, using espcrc1.sty and wrapfig.sty (included), two figures. Talk presented by J. Templon at the 15th Int. Conf. on Few-Body Problems in Physics, Groningen, The Netherlands, 22-26 July, 199

    An exploratory study of the relationship between store image, trust, satisfaction and loyalty in a franchise setting

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    This study aims to shed insight on how young shoppers, between theages of 21 and 35, perceive, and relate to, franchise and corporateownedstores in the supermarket industry. This is achieved by investigating the roles of store image, trust and satisfaction in predicting loyalty to a particular store type. By analysing empirical results, this study shows that compared to corporate-owned stores, consumers have an overall better perception of franchise stores, especially in terms of trust and customer satisfaction. Examining an integrative loyalty framework, the study shows diff erential eff ects in how Store Image elements infl uence customer Loyalty indirectlythrough satisfaction, and how Trust elements infl uence customer Loyalty indirectly through Satisfaction

    A thermodynamic unification of jamming

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    Fragile materials ranging from sand to fire-retardant to toothpaste are able to exhibit both solid and fluid-like properties across the jamming transition. Unlike ordinary fusion, systems of grains, foams and colloids jam and cease to flow under conditions that still remain unknown. Here we quantify jamming via a thermodynamic approach by accounting for the structural ageing and the shear-induced compressibility of dry sand. Specifically, the jamming threshold is defined using a non-thermal temperature that measures the 'fluffiness' of a granular mixture. The thermodynamic model, casted in terms of pressure, temperature and free-volume, also successfully predicts the entropic data of five molecular glasses. Notably, the predicted configurational entropy avoids the Kauzmann paradox entirely. Without any free parameters, the proposed equation-of-state also governs the mechanism of shear-banding and the associated features of shear-softening and thickness-invariance.Comment: 16 pgs double spaced. 4 figure

    Filling the gap between chemical carcinogenesis and the hallmarks of cancer: a temporal perspective

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    Background Cancer is believed to arise through the perturbation of pathways and the order of pathway perturbation events can enhance understanding and evaluation of carcinogenicity. This order has not been examined so far, and this study aimed to fill this gap by attempting to gather evidence on the potential temporal sequence of events in carcinogenesis. Design The methodology followed was to discuss first the temporal sequence of hallmarks of cancer from the point of view of pathological specimens of cancer (essentially branched mutations) and then to consider the hallmarks of cancer that one well‐known carcinogen, benzo(a)pyrene, can modify. Results Even though the sequential order of driving genetic alterations can vary between and within tumours, the main cancer pathways affected are almost ubiquitous and follow a generally common sequence: resisting cell death, insensitivity to antigrowth signals, sustained proliferation, deregulated energetics, replicative immortality and activation of invasion and metastasis. The first 3 hallmarks can be regarded as almost simultaneous while angiogenesis and avoiding immune destruction are perhaps the only hallmarks with a varying position in the above sequence. Conclusions Our review of hallmarks of cancer and their temporal sequence, based on mutational spectra in biopsies from different cancer sites, allowed us to propose a hypothetical temporal sequence of the hallmarks. This sequence can add molecular support to the evaluation of an agent as a carcinogen as it can be used as a conceptual framework for organising and evaluating the strength of existing evidence

    Comparative analysis of political systems and ethnic mobilization:Assimilation versus exclusion

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    The success of minority nationalisms and their claim to autonomy is primarily dependent on the popular support they receive from their constituencies. Aspirations of minority groups demanding self-rule are also accepted as democratic because of this popular consent. The unsuccessful autonomy referendums in both Puerto Rico and Corsica, however, deviated from this trend leaving questions behind about where and when autonomy is likely to be a democratic and realistic solution. The article elaborates on five variables explaining popular support for ethnonationalism and questions their reliability across the cases of Quebec, Flanders and Western Thrace. Experimenting with the most different systems design (the Mill’s method of agreement), this article concludes that minority nationalism is stronger in political systems of ethnic differentiation than assimilation. The article also verifies this in the contrasting cases of Corsica and Puerto Rico where the nationalist factions failed to mobilize their ethnic constituency because of their political culture being divided by the political systems of integration and assimilation.Publisher Statement: The final publication is available at Springer via http://dx.doi.org/10.1057/s41295-016-0004-

    Pairing in nuclear systems: from neutron stars to finite nuclei

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    We discuss several pairing-related phenomena in nuclear systems, ranging from superfluidity in neutron stars to the gradual breaking of pairs in finite nuclei. We focus on the links between many-body pairing as it evolves from the underlying nucleon-nucleon interaction and the eventual experimental and theoretical manifestations of superfluidity in infinite nuclear matter and of pairing in finite nuclei. We analyse the nature of pair correlations in nuclei and their potential impact on nuclear structure experiments. We also describe recent experimental evidence that points to a relation between pairing and phase transitions (or transformations) in finite nuclear systems. Finally, we discuss recent investigations of ground-state properties of random two-body interactions where pairing plays little role although the interactions yield interesting nuclear properties such as 0+ ground states in even-even nuclei.Comment: 74 pages, 33 figs, uses revtex4. Submitted to Reviews of Modern Physic
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