Fermions and bosons in nonsymmorphic PdSb2 with sixfold degeneracy

PdSb2 is a candidate for hosting 6-fold-degenerate exotic fermions (beyond Dirac and Weyl fermions).The nontrivial band crossing protected by the nonsymmorphic symmetry plays a crucial role in physical properties. We have grown high-quality single crystals of PdSb2 and characterized their physical properties under several stimuli (temperature, magnetic field, and pressure). While it is a diamagnetic Fermi-liquid metal under ambient pressure, PdSb2 exhibits a large magnetoresistance with continuous increase up to 14 T, which follows the Kohler's scaling law at all temperatures. This implies one-band electrical transport, although multiple bands are predicted by first principles calculations. By applying magnetic field along the [111] direction, de Haas-van Alphen oscillations are observed with frequency of 102 T. The effective mass is nearly zero (0.045m0) with the Berry phase close to {\pi}, confirming that the band close to the R point has a nontrivial character. Under quasihydrostatic pressure (p), evidence for superconductivity is observed in the resistivity below the critical temperature Tc. The dome-shaped Tc versus p is obtained with maximum Tc~2.9 K. We argue that the formation of Cooper pairs (bosons) is the consequence of the redistribution of the 6-fold-degenerate fermions under pressure

High definition systems in Japan

The successful implementation of a strategy to produce high-definition systems within the Japanese economy will favorably affect the fundamental competitiveness of Japan relative to the rest of the world. The development of an infrastructure necessary to support high-definition products and systems in that country involves major commitments of engineering resources, plants and equipment, educational programs and funding. The results of these efforts appear to affect virtually every aspect of the Japanese industrial complex. The results of assessments of the current progress of Japan toward the development of high-definition products and systems are presented. The assessments are based on the findings of a panel of U.S. experts made up of individuals from U.S. academia and industry, and derived from a study of the Japanese literature combined with visits to the primary relevant industrial laboratories and development agencies in Japan. Specific coverage includes an evaluation of progress in R&D for high-definition television (HDTV) displays that are evolving in Japan; high-definition standards and equipment development; Japanese intentions for the use of HDTV; economic evaluation of Japan's public policy initiatives in support of high-definition systems; management analysis of Japan's strategy of leverage with respect to high-definition products and systems

Competing magnetic states, disorder, and the magnetic character of Fe3Ga4

The physical properties of metamagnetic Fe$_3$Ga$_4$ single crystals are investigated to explore the sensitivity of the magnetic states to temperature, magnetic field, and sample history. The data reveal a moderate anisotropy in the magnetization and the metamagnetic critical field along with features in the specific heat at the magnetic transitions $T_1=68$ K and $T_2=360$ K. Both $T_1$ and $T_2$ are found to be sensitive to the annealing conditions of the crystals suggesting that disorder affects the competition between the ferromagnetic (FM) and antiferromagnetic (AFM) states. Resistivity measurements reveal metallic transport with a sharp anomaly associated with the transition at $T_2$. The Hall effect is dominated by the anomalous contribution which rivals that of magnetic semiconductors in magnitude ($-5 \mu \Omega$ cm at 2 T and 350 K) and undergoes a change of sign upon cooling into the low temperature FM state. The temperature and field dependence of the Hall effect indicate that the magnetism is likely to be highly itinerant in character and that a significant change in the electronic structure accompanies the magnetic transitions. We observe a contribution from the topological Hall effect in the AFM phase suggesting a non-coplanar contribution to the magnetism. Electronic structure calculations predict an AFM ground state with a wavevector parallel to the crystallographic $c$-axis preferred over the experimentally measured FM state by $\approx$ 50 meV per unit cell. However, supercell calculations with a small density of Fe-antisite defects introduced tend to stabilize the FM over the AFM state indicating that antisite defects may be the cause of the sensitivity to sample synthesis conditions.Comment: 13 pages, 14 figures, and 4 supplementary table

Exploring Pompeii: discovering hospitality through research synergy

Hospitality research continues to broaden through an ever-increasing dialogue and alignment with a greater number of academic disciplines. This paper demonstrates how an enhanced understanding of hospitality can be achieved through synergy between archaeology, the classics and sociology. It focuses on classical Roman life, in particular Pompeii, to illustrate the potential for research synergy and collaboration, to advance the debate on hospitality research and to encourage divergence in research approaches. It demonstrates evidence of commercial hospitality activities through the excavation hotels, bars and taverns, restaurants and fast food sites. The paper also provides an example of the benefits to be gained from multidisciplinary analysis of hospitality and tourism

Effective descriptions of branes on non-geometric tori

We investigate the low-energy effective description of non-geometric compactifications constructed by T-dualizing two or three of the directions of a T^3 with non-vanishing H-flux. Our approach is to introduce a D3-brane in these geometries and to take an appropriate decoupling limit. In the case of two T-dualities, we find at low energies a non-commutative T^2 fibered non-trivially over an S^1. In the UV this theory is still decoupled from gravity, but is dual to a little string theory with flavor. For the case of three T-dualities, we do not find a sensible decoupling limit, casting doubt on this geometry as a low-energy effective notion in critical string theory. However, by studying a topological toy model in this background, we find a non-associative geometry similar to one found by Bouwknegt, Hannabuss, and Mathai.Comment: 22 pages, 4 figures, references adde

Efeito do cruzamento sobre o crescimento de caprinos no Ceará.

Cruzaram-se, na Fazenda Iracema, da Empresa de Pesquisa Agropecuaria do Ceara - EPACE -, em Quixada, CE, 420 cabras Sem Raça Definida (SRD) com reprodutores das raças e/ou tipos Nativos - Marota, Canindé, Moxoto, Repartida e SRD - e exoticas Anglo-Nubiana e Bhuj. Pesaram-se as crias ao nascer e a intervalos de 28 dias até 112 dias (desmama) e a cada dois meses, até 12 meses. 0 peso ao nascer, dos descendentes de raças exoticas, foi maior que o das lrças nativas. Subseqüentemente, os pesos foram idênticos em todos os grupos, refletindo efeito materno. Aos 12 meses, os descendentes de Anglo-Nubiana tenderam a ser mais pesados que os de Bhuj e SRD, e estes, que aqueles das raças nativas (22,09; 20,55 e 19 kg). Os descendentes das raças nativas foram levemente inferiores aos de SRD, mostrando que essas raças podem estar estreitamente relacionadas corn o tipo SRD. Os machos foram mais pesados que as fêmeas, ao nascer (2,28 e 1,94 kg) e no período pos-desmama. Os nascidos de partos simples foram mais pesados que os nascidos de partos gemelares, até seis meses de idade. 0 peso da mae no parto influenciou o peso das crias no nascimento. [Cross-breed effect upon the growth of goats in Ceará state]. Abstract: Four hundred and twenty SRD (nondescripted breed) does were cross-breeded at Iracerna Farm of the Empresa de Pesquisa Agropecuária do Ceará in Quixadá, Ceará, CE, Brazil, with sires of the nativo breeds Marota, Canindé, Repartida, Moxotó and SRD and exotic breeds Anglo-Nubian and Bhuj. The kids were weighed at birth and each 28 days up to weaning and each two months frorn weaning to 12 months of age. At birth, livo weight were higher for exotics cross-breeded kids as compared to native ones. Subsequently, live weights were the sarne for ali kids, showing great maternal effect on the growth of kids. By 12 rnonths old Anglo-Nubian cross-breeded kids were heavier than Bhuj and SRD, and these were heavier than the nativo ones (22.09, 20.55 and 19kg). Nativa breed progeny did not show advantage over SRD crosses. This suggests that native breeds may be closely reiated to SRD. Male kids were havier than female at birth (2.28 to 1.94 kg), and even during post-weaning growth. Kids bom single were heavier than twins from birth to Mx month old. Does weight at parturition affected the kids weight at birth

Superstring partition functions in the doubled formalism

Computation of superstring partition function for the non-linear sigma model on the product of a two-torus and its dual within the scope of the doubled formalism is presented. We verify that it reproduces the partition functions of the toroidally compactified type--IIA and type--IIB theories for appropriate choices of the GSO projection.Comment: 15 page

The Non Linear Sigma Model and Spin Ladders

The well known Haldane map from spin chains into the $O(3)$ non linear sigma model is generalized to the case of spin ladders. This map allows us to explain the different qualitative behaviour between even and odd ladders, exactly in the same way it explains the difference between integer and half-integer spin chains. Namely, for even ladders the topological term in the sigma model action is absent, while for odd ladders the $\theta$ parameter, which multiplies the topological term, is equal to $2 \pi S$, where $S$ is the spin of the ladder. Hence even ladders should have a dynamically generated spin gap, while odd ladders with half-integer spin should stay gapless, and physically equivalent to a perturbed $SU(2)_1$ Wess-Zumino -Witten model in the infrared regime. We also derive some consequences from the dependence of the sigma model coupling constant on the ladder Heisenberg couplings constants.Comment: Latex file, 14 pages, no figure

Generalized Flux Vacua

We consider type II string theory compactified on a symmetric T^6/Z_2 orientifold. We study a general class of discrete deformations of the resulting four-dimensional supergravity theory, including gaugings arising from geometric and "nongeometric'' fluxes, as well as the usual R-R and NS-NS fluxes. Solving the equations of motion associated with the resulting N = 1 superpotential, we find parametrically controllable infinite families of supersymmetric vacua with all moduli stabilized. We also describe some aspects of the distribution of generic solutions to the SUSY equations of motion for this model, and note in particular the existence of an apparently infinite number of solutions in a finite range of the parameter space of the four-dimensional effective theory.Comment: 30 pages, 4 .eps figures; v2, reference adde

Massive and Massless Behavior in Dimerized Spin Ladders

We investigate the conditions under which a gap vanishes in the spectrum of dimerized coupled spin-1/2 chains by means of Abelian bosonization and Lanczos diagonalization techniques. Although both interchain ($J'$) and dimerization ($\delta$) couplings favor a gapful phase, it is shown that a suitable choice of these interactions yields massless spin excitations. We also discuss the influence of different arrays of relative dimerization on the appearance of non-trivial magnetization plateaus.Comment: 5 pages, RevTex, 5 Postscript figure