13 research outputs found
Diminished equilibrium magnetization in Hg-1223 and Tl-2212 superconductors with fission-generated columnar defects
New Upper Limit of Terrestrial Equivalence Principle Test for Rotating Extended Bodies
Improved terrestrial experiment to test the equivalence principle for
rotating extended bodies is presented, and a new upper limit for the violation
of the equivalence principle is obtained at the level of 1.6, which is limited by the friction of the rotating gyroscope. It
means the spin-gravity interaction between the extended bodies has not been
observed at this level.Comment: 4 page
Local and Global Casimir Energies: Divergences, Renormalization, and the Coupling to Gravity
From the beginning of the subject, calculations of quantum vacuum energies or
Casimir energies have been plagued with two types of divergences: The total
energy, which may be thought of as some sort of regularization of the
zero-point energy, , seems manifestly divergent. And
local energy densities, obtained from the vacuum expectation value of the
energy-momentum tensor, , typically diverge near
boundaries. The energy of interaction between distinct rigid bodies of whatever
type is finite, corresponding to observable forces and torques between the
bodies, which can be unambiguously calculated. The self-energy of a body is
less well-defined, and suffers divergences which may or may not be removable.
Some examples where a unique total self-stress may be evaluated include the
perfectly conducting spherical shell first considered by Boyer, a perfectly
conducting cylindrical shell, and dilute dielectric balls and cylinders. In
these cases the finite part is unique, yet there are divergent contributions
which may be subsumed in some sort of renormalization of physical parameters.
The divergences that occur in the local energy-momentum tensor near surfaces
are distinct from the divergences in the total energy, which are often
associated with energy located exactly on the surfaces. However, the local
energy-momentum tensor couples to gravity, so what is the significance of
infinite quantities here? For the classic situation of parallel plates there
are indications that the divergences in the local energy density are consistent
with divergences in Einstein's equations; correspondingly, it has been shown
that divergences in the total Casimir energy serve to precisely renormalize the
masses of the plates, in accordance with the equivalence principle.Comment: 53 pages, 1 figure, invited review paper to Lecture Notes in Physics
volume in Casimir physics edited by Diego Dalvit, Peter Milonni, David
Roberts, and Felipe da Ros
Central Collisions of Au on Au at 150, 250 and 400 A MeV
Collisions of Au on Au at incident energies of 150, 250 and 400 A MeV were
studied with the FOPI-facility at GSI Darmstadt. Nuclear charge (Z < 16) and
velocity of the products were detected with full azimuthal acceptance at
laboratory angles of 1-30 degrees. Isotope separated light charged particles
were measured with movable multiple telescopes in an angular range of 6-90
degrees. Central collisions representing about 1 % of the reaction cross
section were selected by requiring high total transverse energy, but vanishing
sideflow. The velocity space distributions and yields of the emitted fragments
are reported. The data are analysed in terms of a thermal model including
radial flow. A comparison with predictions of the Quantum Molecular Model is
presented.Comment: LateX text 62 pages, plus six Postscript files with a total of 34
figures, accepted by Nucl.Phys.
Diminished equilibrium magnetization in Hg-1223 and Tl-2212 superconductors with fission-generated columnar defects
Ossandon, J.G. Department of Engineering Sciences, Universidad de Talca, Curicó, Chile.Abstract
When randomly oriented columnar defects (CDs) are added to Hg-1223 and Tl-2212 superconductors, their vortex state equilibrium magnetization Meq decreases substantially. Meq progressively deviates from the usual London ln(B) dependence and the curves become S-shaped. Vortex-defect interactions quantitatively account for this behavio
Pinning action of correlated disorder against equilibrium properties of HgBa2Ca2Cu3Ox
Ossandon, J.G. Department of Engineering Sciences, Universidad de Talca, Curicó, Chile.We report significant alteration of the equilibrium properties of the superconductor HgBaCaCuO when correlated disorder in the form of randomly oriented columnar tracks is introduced via induced fission of Hg-nuclei. From studies of the equilibrium magnetization and the persistent current density over a wide range of temperatures, applied magnetic fields, and track densities up to a ``matching field'' of 3.4 Tesla, we observe that the addition of more columnar tracks acting as pinning centers is progressively offset by reductions in the magnitude of . Invoking anisotropy induced ``refocusing'' of the random track array and incorporating vortex-defect interactions, we find that this corresponds to increases in the London penetration depth ; this reduces the vortex line energy and consequently reduces the pinning effectiveness of the tracks
Coding of facial expressions of pain in the laboratory mouse
Facial expression is widely used as a measure of pain in infants; whether nonhuman animals display such pain expressions has never been systematically assessed. We developed the mouse grimace scale (MGS), a standardized behavioral coding system with high accuracy and reliability; assays involving noxious stimuli of moderate duration are accompanied by facial expressions of pain. This measure of spontaneously emitted pain may provide insight into the subjective pain experience of mice.Paroxysmal Cerebral Disorder
Multinational corporations and industrial relations research: A road less travelled
While there is a large body of academic debate surrounding human resource management issues in MNCs, industrial relations issues often fail to receive the same degree of attention. This paper attempts to move the debate forward by critically reviewing some of the key debates surrounding industrial relations (IR) in an international context. Firstly, some key themes surrounding the comparison of industrial relations across borders and IR in multinational companies are delineated and defined. We then consider the reasons why an international IR (IIR) perspective has been under-represented in the literature to date. The paper then explores the contribution which an international IR perspective can bring to the study of management practices in MNCs. This is discussed in terms of IIR¿s potential contribution in terms of an alternative analytical approach and also differences in its substantive coverage. The impact of IR systems on MNC location and relocation decisions, key issues for employees, trade unions and managers of MNCs, is then discussed as an example of the former. We then consider the potential for, and evidence of, international collective bargaining as a potential counter-balance to the power the MNC in the global environment as an example of a differing area of substantive coverage of IIR. Finally some avenues for potential study are outlined.peer-reviewe
Structure and Properties of Nanoparticles Formed by Ion Implantation
This chapter broadly describes the formation, basic microstructure, and fundamental optoelectronic properties of nanocomposites synthesized by ion implantation. It is not meant as a complete literature survey and by no means includes all references on a subject that has seen a considerable amount of research effort in the past 15 years. However, it should be a good starting point for those new to the field and in a concise way summarize the main lines of research by discussing the optical, magnetic, and smart properties of these nanoparticles and the dependence of these properties on the overall microstructure. The chapter concludes with an outlook for the future