Theory on the Stability of the Ferromagnetic Double Layer Structure and on the Peak Structure of the Magneto-Optical Spectra of CeSb

We propose the pf+pd mixing model for CeSb to explain the stability of the ferromagnetic double layer structure in the magnetic ordering. The pd mixing causes the saddle type singular points, neighboring the $\Delta$ axis, for the bands which gain energy through the pf hybridization with the occupied f state. The peak of the density of states due to this combined effect of the pf mixing and the pd mixing enhances the stability of the double layer structure. The same combined effect also causes the saddle type singular points in the joint density of states of the optical transition. The peak structure of the magneto-optical spectra which has been observed in experiments is explained by the present model.Comment: 9 pages, 14 figure

The blood labyrinthine barrier in the human normal and Meniere's disease macula utricle.

The ultrastructural organization of the blood labyrinthine barrier (BLB) was investigated in the human vestibular endorgan, the utricular macula, using postmortem specimens from individuals with documented normal auditory and vestibular function and surgical specimens from patients with intractable Meniere's disease. Transmission electron microscopic analysis of capillaries located in the normal human utricular stroma showed vascular endothelial cells with few pinocytotic vesicles, covered by a smooth and uniform basement membrane surrounded by pericyte processes. Meniere's disease specimens revealed differential ultrastructural pathological changes in the cellular elements of the microvasculature. With moderate degeneration of the BLB, there were numerous vesicles within the vascular endothelial cells (VECs), with increased numbers at the abluminal face, pericyte process detachment and disruption of the perivascular basement membrane surrounding the VECs. With severe degeneration of the BLB, there was severe vacuolization or frank apparent necrosis of VECs and loss of subcellular organelles. A higher severity of BLB degenerative changes was associated with a higher degree of basement membrane thickening and edematous changes within the vestibular stroma. This study presents the first ultrastructural analysis of the capillaries constituting the BLB in the human vestibular macula utricle from normal and Meniere's disease

GreeM : Massively Parallel TreePM Code for Large Cosmological N-body Simulations

In this paper, we describe the implementation and performance of GreeM, a massively parallel TreePM code for large-scale cosmological N-body simulations. GreeM uses a recursive multi-section algorithm for domain decomposition. The size of the domains are adjusted so that the total calculation time of the force becomes the same for all processes. The loss of performance due to non-optimal load balancing is around 4%, even for more than 10^3 CPU cores. GreeM runs efficiently on PC clusters and massively-parallel computers such as a Cray XT4. The measured calculation speed on Cray XT4 is 5 \times 10^4 particles per second per CPU core, for the case of an opening angle of \theta=0.5, if the number of particles per CPU core is larger than 10^6.Comment: 13 pages, 11 figures, accepted by PAS

Environmental effect on the subhalo abundance -- a solution to the missing dwarf problem

Recent high-resolution simulations of the formation of dark-matter halos have shown that the distribution of subhalos is scale-free, in the sense that if scaled by the velocity dispersion of the parent halo, the velocity distribution function of galaxy-sized and cluster-sized halos are identical. For cluster-sized halos, simulation results agreed well with observations. Simulations, however, predicted far too many subhalos for galaxy-sized halos. Our galaxy has several tens of known dwarf galaxies. On the other hands, simulated dark-matter halos contain thousands of subhalos. We have performed simulation of a single large volume and measured the abundance of subhalos in all massive halos. We found that the variation of the subhalo abundance is very large, and those with largest number of subhalos correspond to simulated halos in previous studies. The subhalo abundance depends strongly on the local density of the background. Halos in high-density regions contain large number of subhalos. Our galaxy is in the low-density region. For our simulated halos in low-density regions, the number of subhalos is within a factor of three to that of our galaxy. We argue that the ``missing dwarf problem'' is not a real problem but caused by the biased selection of the initial conditions in previous studies, which were not appropriate for field galaxies.Comment: 8 pages, 5 figures, higher resolution run added, accepted by PAS

Gamma-ray Signal from Earth-mass Dark Matter Microhalos

Earth-mass dark matter microhalos with size of ~100 AUs are the first structures formed in the universe, if the dark matter of the Universe are made of neutralino. Here, we report the results of ultra-high-resolution simulations of the formation and evolution of these microhalos. We found that microhalos have the central density cusps of the form $\rho \propto r^{-1.5}$, much steeper than the cusps of larger dark halos. The central regions of these microhalos survive the encounters with stars except in very inner region of the galaxy down to the radius of a few hundreds pcs from the galactic center. The annihilation signals from nearest microhalos are observed as gamma-ray point-sources (radius less than 1'), with unusually large proper motions of ~0.2 degree per year. Their surface brightnesses are ~10% of that of the galactic center. Their S/N ratios might be better if they are far from the galactic plane. Luminosities of subhalos are determined only by their mass, and they are more than one order of magnitude luminous than the estimation by Springel et al. (2008): A boost factor can be larger than 1000. Perturbations to the millisecond pulsars by gravitational attractions of nearby earth-mass microhalos can be detected by the observations of Parkes Pulsar Timing Array (PPTA).Comment: 15 pages, 5 figures, accepted by ApJ

Changing Notions of Environmental Justice in the Decision to Host a Nuclear Fuel Storage Facility on the Skull Valley Goshute Reservation

This paper examines the conflict surrounding the Skull Valley Band of Goshute Indians' decision to host an interim storage facility for high-level radioactive waste on their reservation in Utah. This paper challenges the predominant tradition of environmental justice scholarship and activism that focus on the inequitable distribution of hazards in low-income minority communities. We examine the underlying historical, political, and geographical contexts of the emerging nuclear landscape of the American West and focus on how the political and environmental dynamics of siting a nuclear facility intersect with issues of community self-determination and identity formation. Specifically, we examine notions of tribal sovereignty and contemporary tribal identity politics and how these complicate and hinder tribal involvement in a full range of decisions about development. Environmental justice activism and literature tend to restrictively define the authentic indigenous response to development and natural resource management, particularly when projects are controversial and technologically complex. The restrictive definition expects that tribes will refuse to grapple with technology, calling it an anti-spiritual manifestation of the non-tribal world. In labeling the tribal response, there is no distinction made between the variety of indigenous players and distinct communities represented, the differing scopes of governing authority, and heterogeneous responses to projects tagged as environmentally unjust. Rarely is there discussion of the range of values placed on specific sites by specific tribes and how these values should inform development decisions. Finally, this view of "authentic," legitimate tribal involvement undermines the capacity building necessary for tribes to achieve a level of sovereignty and justice where they are educated and proactive in a full range of development and resource management decisions

Symmetry and Z_2-Orbifolding Approach in Five-dimensional Lattice Gauge Theory

In a lattice gauge-Higgs unification scenario using a Z_2-orbifolded extra-dimension, we find a new global symmetry in a case of SU(2) bulk gauge symmetry. It is a global symmetry on sites in a fixed point with respect to Z_2-orbifolding, independent of the bulk gauge symmetry. It is shown that the vacuum expectation value of a Z_2-projected Polyakov loop is a good order parameter of the new symmetry. The effective theory on lattice is also discussed.Comment: 13 pages, 3 figures; refined the explanation