1,846 research outputs found
Quantum Melting of Charge Order due to Frustration in Two-Dimensional Quarter-Filled Systems
The effect of geometrical frustration in a two-dimensional 1/4-filled
strongly correlated electron system is studied theoretically, motivated by
layered organic molecular crystals. An extended Hubbard model on the square
lattice is considered, with competing nearest neighbor Coulomb interaction, V,
and that of next-nearest neighbor along one of the diagonals, V', which favor
different charge ordered states. Based on exact diagonalization calculations,
we find a metallic phase stabilized over a broad window at V' ~ V even for
large Coulomb repulsion strengths as a result of frustrating the charge ordered
states. Slightly modifying the lattice geometry relevant to the actual organic
compounds does not alter the results, suggesting that this `quantum melting' of
charge order is a robust feature of frustrated strongly correlated 1/4-filled
systems.Comment: 5 pages, 4 figures, to be published in Phys. Rev.
Dilaton and Second-Rank Tensor Fields as Supersymmetric Compensators
We formulate a supersymmetric theory in which both a dilaton and a
second-rank tensor play roles of compensators. The basic off-shell multiplets
are a linear multiplet (B_{\mu\nu}, \chi, \phi) and a vector multiplet (A_\mu,
\l; C_{\mu\nu\rho}), where \phi and B_{\m\n} are respectively a dilaton and a
second-rank tensor. The third-rank tensor C_{\mu\nu\rho} in the vector
multiplet is 'dual' to the conventional D-field with 0 on-shell or 1 off-shell
degree of freedom. The dilaton \phi is absorbed into one longitudinal component
of A_\mu, making it massive. Initially, B_{\mu\nu} has 1 on-shell or 3
off-shell degrees of freedom, but it is absorbed into the longitudinal
components of C_{\mu\nu\rho}. Eventually, C_{\mu\nu\rho} with 0 on-shell or 1
off-shell degree of freedom acquires in total 1 on-shell or 4 off-shell degrees
of freedom, turning into a propagating massive field. These basic multiplets
are also coupled to chiral multiplets and a supersymmetric Dirac-Born-Infeld
action. Some of these results are also reformulated in superspace. The proposed
mechanism may well provide a solution to the long-standing puzzle of massless
dilatons and second-rank tensors in supersymmetric models inspired by string
theory.Comment: 15 pages, no figure
The Vertex-Face Correspondence and the Elliptic 6j-symbols
A new formula connecting the elliptic -symbols and the fusion of the
vertex-face intertwining vectors is given. This is based on the identification
of the fusion intertwining vectors with the change of base matrix elements
from Sklyanin's standard base to Rosengren's natural base in the space of even
theta functions of order . The new formula allows us to derive various
properties of the elliptic -symbols, such as the addition formula, the
biorthogonality property, the fusion formula and the Yang-Baxter relation. We
also discuss a connection with the Sklyanin algebra based on the factorised
formula for the -operator.Comment: 23 page
Elastic properties of the Non-Fermi liquid metal and the Dense Kondo semiconductor
We have investigated the elastic properties of the Ce-based filled
skutterudite antimonides CeRuSb and CeOsSb by means
of ultrasonic measurements. CeRuSb shows a slight increase around
130 K in the temperature dependence of the elastic constants ,
(-)/2 and . No apparent softening toward low
temperature due to a quadrupolar response of the 4-electronic ground state
of the Ce ion was observed at low temperatures. In contrast CeOsSb
shows a pronounced elastic softening toward low temperature in the longitudinal
as a function of temperature () below about 15 K, while a slight
elastic softening was observed in the transverse below about 1.5 K.
Furthermore, CeOsSb shows a steep decrease around a phase
transition temperature of 0.9 K in both and. The elastic
softening observed in below about 15 K cannot be explained
reasonably only by the crystalline electric field effect. It is most likely to
be responsible for the coupling between the elastic strain and the
quasiparticle band with a small energy gap in the vicinity of Fermi level. The
elastic properties and the 4 ground state of Ce ions in CeRuSb
and CeOsSb are discussed from the viewpoint of the crystalline
electric field effect and the band structure in the vicinity of Fermi level.Comment: 9 pages, 11 figures, regular pape
Association of Serotonin2c Receptor Polymorphisms With Antipsychotic Drug Response in Schizophrenia
There is conflicting evidence for the association between genetic polymorphisms in the serotonin (5-HT)2C receptor (HTR2C) and response to antipsychotic drugs (APD) in schizophrenic patients. We tested the association between the HTR2C polymorphisms, Cys23Ser, −759C/T, and −697G/C, and response to APDs (mainly clozapine) in a 6 month prospective study in 171 patients with schizophrenia. Ser23 was significantly associated with treatment response (positive symptoms, X2 = 7.540, p = 0.01; negative symptoms, X2 = 4.796, p = 0.03) in male patients only. A −759C-Ser23 haplotype was similar associated with positive (X2 = 6.648, p = 0.01) and negative (X2 = 6.702, p = 0.01) symptom improvement. Logistic regression, after controlling for covariates, also showed significant haplotypic associations. A meta-analysis of six studies for Ser23 and treatment response showed an overall odds ratio of 2.00 (95%CI, 1.38–2.91, p = 0.0003) or 1.94 (95%CI, 1.27–2.99, p = 0.0024) under fixed or random effect models. These results provide additional evidence that HTR2C polymorphisms are associated with treatment response to APD with HTR2C antagonism or inverse agonism, in male schizophrenic patients
Dengue Vectors and their Spatial Distribution
The distribution of dengue vectors, Ae. aegypti and Ae. albopictus, is affected by climatic factors. In addition, since their life cycles are well adapted to the human environment, environmental changes resulting from human activity such as urbanization exert a great impact on vector distribution. The different responses of Ae. aegypti and Ae albopictus to various environments result in a difference in spatial distribution along north-south and urban-rural gradients, and between the indoors and outdoors. In the north-south gradient, climate associated with survival is an important factor in spatial distribution. In the urban-rural gradient, different distribution reflects a difference in adult niches and is modified by geographic and human factors. The direct response of the two species to the environment around houses is related to different spatial distribution indoors and outdoors. Dengue viruses circulate mainly between human and vector mosquitoes, and the vector presence is a limiting factor of transmission. Therefore, spatial distribution of dengue vectors is a significant concern in the epidemiology of the disease
The Elliptic Algebra U_{q,p}(sl_N^) and the Deformation of W_N Algebra
After reviewing the recent results on the Drinfeld realization of the face
type elliptic quantum group B_{q,lambda}(sl_N^) by the elliptic algebra
U_{q,p}(sl_N^), we investigate a fusion of the vertex operators of
U_{q,p}(sl_N^). The basic generating functions \Lambda_j(z) (j=1,2,.. N-1) of
the deformed W_N algebra are derived explicitly.Comment: 15 pages, to appear in Journal of physics A special issue - RAQIS0
Outgrowth by fin motor axons in wildtype and a finless mutant of the Japanese medaka fish
The outgrowth of motor axons to the developing pectoral fin of the Japanese medaka fish (Oryzias latipes) was investigated both in wildtype embryos and in the pectoral finless (pl) mutants in which adults are missing pectoral fins. Late in embryogenesis the pectoral fin is a simple limb which contains two antagonist muscles which are innervated by presumptive motor neurons from the first four spinal segments (S1-4). The pectoral fin develops from a fin bud located in S1 and S2 centered on the border between S1 and S2 and, as with other limbs, one of the earliest signs of differentiation is the apical ectodermal ridge (AER). By the time the AER is well formed the growth cones of the presumptive motor neurons have reached the base of the fin bud and formed a plexus by extending toward the fin bud upon emergence from the spinal cord. This is especially evident on the ventral surface of the metamerically arranged axial muscles. For example, growth cones from S2 extend in a diagonal direction (both anterior and lateral) towards the fin bud. One hypothesis which can account for the pattern of motor outgrowth is that growth cones are attracted to the base of the fin bud, perhaps via a long distance cue. This hypothesis was tested by examining outgrowth of segmental nerves in pl embryos in which the fin buds arrest early in development following the initial appearance of the AER. In pl, nerves from S1-4 converged to form a plexus at the base of the abnormal fin bud, but the pattern of outgrowth varied from wildtype in a way consistent with a diminished capacity of the fin bud to attract segmental nerves to it.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29235/1/0000290.pd
- …