7,456 research outputs found

    The isodiametric problem with lattice-point constraints

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    In this paper, the isodiametric problem for centrally symmetric convex bodies in the Euclidean d-space R^d containing no interior non-zero point of a lattice L is studied. It is shown that the intersection of a suitable ball with the Dirichlet-Voronoi cell of 2L is extremal, i.e., it has minimum diameter among all bodies with the same volume. It is conjectured that these sets are the only extremal bodies, which is proved for all three dimensional and several prominent lattices.Comment: 12 pages, 4 figures, (v2) referee comments and suggestions incorporated, accepted in Monatshefte fuer Mathemati

    Radio astrometry with chromatic AGN core positions

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    Aims: The effect of frequency-dependent AGN core positions (``core-shifts'') on radio Very Long Baseline Interferometry (VLBI) global astrometry measurements is investigated. Methods: The basic equations relating to VLBI astrometry are reviewed, including the effects of source structure. A power-law representation of core-shifts, based on both observations and theoretical considerations of jet conditions, is incorporated. Results: It is shown that, in the presence of core-shifts, phase and group-delay astrometry measurements yield different positions. For a core displacement from the jet base parametrized by Delta x (lambda) = k lambda^beta group delays measure a ``reduced'' core-shift of (1-beta) Delta x (lambda). For the astrophysically-significant case of beta = 1, group delays measure no shift at all, giving the position of the jet base. At 8.4 GHz an estimated typical offset between phase and group-delay positions of ~170 uas is smaller than the current ~250 uas precision of group-delay positions of the sources used to define the ICRF; however, this effect must be taken into account for future measurements planned with improved accuracy when comparing with optical positions of AGN to be obtained with the GAIA mission.Comment: Accepted for publication in Astronomy & Astrophysics, 4 page

    He Scores Through a Screen: Mediating Masculinities Through Hockey Video Games

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    Hockey video games highlight the ways in which the video game medium shapes and conditions the experience of producing and/or performing the sport “in real life.” Indeed, the accumulation of advanced statistics in and through the constant evaluation, measurement, and surveillance which are inherent to video games—and increasingly seen as foundational for sport—reveals important contradictions not only in the way the embodied sport is played and understood, but also in terms of the proofs of masculinity upon which the sport is built. It then becomes clear that the building of masculinity and the empowerment of the character become one and the same. The ludic function reinforces the cultural imperative and vice versa. Thus, our chapter prizes apart the conflation of masculinity with hockey while showing the ways that video game studies can contribute to existing disciplines

    Characterizations of hemirings by their hh-ideals

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    In this paper we characterize hemirings in which all hh-ideals or all fuzzy hh-ideals are idempotent. It is proved, among other results, that every hh-ideal of a hemiring RR is idempotent if and only if the lattice of fuzzy hh-ideals of RR is distributive under the sum and hh-intrinsic product of fuzzy hh-ideals or, equivalently, if and only if each fuzzy hh-ideal of RR is intersection of those prime fuzzy hh-ideals of RR which contain it. We also define two types of prime fuzzy hh-ideals of RR and prove that, a non-constant hh-ideal of RR is prime in the second sense if and only if each of its proper level set is a prime hh-ideal of RR

    Same words, different worlds: Exploring differences in researcher and participant understandings of promise and obligation in the psychological contract

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    This paper addresses long-standing questions about promise and obligation, two of the key conceptual building blocks for psychological contract research, are conceptualized and operationalized: How do employees understand these concepts? Would their understandings be congruent with the researchers’ and how would this knowledge inform future psychological contract research? Drawing on interviews with Chinese workers from diverse backgrounds, our results suggest the concepts have distinct meanings for participants in terms of three criteria (defining characteristics, key features and manifestations in employment). We argue that promise and obligation are likely to serve different functions in employment relationship and have different meanings for researchers versus participants, and accordingly we highlight the challenges of using them to conceptualize and operationalize psychological contracts in China and beyond

    Azimuthal asymmetry in unpolarized πN\pi N Drell-Yan process

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    Taking into account the effect of final state interaction, we calculate the non-zero (na\"{i}ve) TT-odd transverse momentum dependent distribution h_1^{\perp}(x,\kp^2) of the pion in a quark-spectator-antiquark model with effective pion-quark-antiquark coupling as a dipole form factor. Using the model result we estimate the cos2ϕ\cos 2\phi asymmetries in the unpolarized πN\pi^- N Drell-Yan process which can be expressed as h1×hˉ1h_1^{\perp}\times\bar{h}_1^{\perp}. We find that the resulting h_{1\pi}^\p(x,\kp^2) has the advantage to reproduce the asymmetry that agrees with the experimental data measured by NA10 Collaboration. We estimate the cos2ϕ\cos2\phi asymmetries averaged over the kinematics of NA10 experiments for 140, 194 and 286 GeV π\pi^- beam and compare them with relevant experimental data.Comment: 11 pages, 4 figures, to appear in PL

    Periostin Is Essential for the Integrity and Function of the Periodontal Ligament During Occlusal Loading in Mice

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141255/1/jper1480.pd
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