396 research outputs found
Gender discourse, awareness, and alternative responses for men in everyday living
In this paper, the authors use examples from their experiences to explore the nuances and complexities of contemporary gender practices. They draw on discourse and positioning theories to identify the ways in which culturally dominant, and difficult to notice, gender constructions help shape everyday experiences. In addition, the authors share their view that there are benefits in developing skills in noticing contemporary practices made available by dominant gender constructions. Such noticing expands possibilities for ways of responding and relating that might produce outcomes for men and women that fit with their hopes for living
Fermi-surface topology and the effects of intrinsic disorder in a class of charge-transfer salts containing magnetic ions: β" — (BEDT — TTF)₄ [(H₃O)M(C₂O₄)₃]Υ (M = Ga, Cr, Fr; Υ = C₅H₅N)
We report high-field magnetotransport measurements on β" — (BEDT — TTF)₄ [(H₃O)M(C₂O₄)₃]Υ, where M =Ga, Cr and Fe and Υ = C₅H₅N. We observe similar Shubnikov–de Haas oscillations in all compounds, attributable to four quasi-two-dimensional Fermi-surface pockets, the largest of which corresponds to a cross-sectional area ≈ 8.5% of the Brillouin zone. The cross-sectional areas of the pockets are in agreement with the expectations for a compensated semimetal, and the corresponding effective masses are ∼mₑ, rather small compared to those of other BEDT-TTF salts. Apart from the case of the smallest Fermi-surface pocket, varying the M ion seems to have little effect on the overall Fermi-surface topology or on the effective masses. Despite the fact that all samples show quantum oscillations at low temperatures, indicative of Fermi liquid behavior, the sample and temperature dependence of the interlayer resistivity suggest that these systems are intrinsically inhomogeneous. It is thought that intrinsic tendency to disorder in the anions and/or the ethylene groups of the BEDT-TTF molecules leads to the coexistence of insulating and metallic states at low temperatures. A notional phase diagram is given for the general family of β" — (BEDT — TTF)₄ [(H₃O)M(C₂O₄)₃]Υ salts
Effects of electron correlations and chemical pressures on superconductivity of β''-type organic compounds
We investigate low-temperature electronic states of the series of organic conductors β'' - [bis(ethylenedithio)tetrathiafulvalene] 4[(H3O)M(C2O4)3] G, where M and G represent trivalent metalions and guest organic molecules, respectively. Our structural analyses reveal that the replacement of M and G give rise to systematic change in the cell parameters, especially in the b-axis length, which has a positive correlation with the superconducting transition temperature Tc. Analysis of temperature and magnetic field dependences of the electrical resistance including the Shubnikov–de Haas oscillations elucidates that the variation of charge disproportionation, the effective mass, and the number of itinerant carriers can be systematically explained by the change of the b-axis length. The changes of the transfer integrals induced by stretching/compressing the b axis are confirmed by the band calculation. We discuss that electron correlations in quarter-filled electronic bands lead to charge disproportionation and the possibility of a novel pairing mechanism of superconductivity mediated by charge degrees of freedom
Stereoisomeric semiconducting radical cation salts of chiral bis(2-hydroxypropylthio)ethylenedithioTTF with tetrafluoroborate anions
The new chiral TTF-based donor molecule bis(2-hydroxypropylthio)ethylenedithiotetrathiafulvalene has produced enantiopure R,R and S,S radical cation salts with the tetrafluoroborate anion as well as the nearly isostructural meso/racemate mixture. The enantiopure R,R or S,S salts are both 1:1 semiconducting salts with activation energies of 0.19–0.24 eV, both crystallising in the orthorhombic space group C2221. The semiconducting salt containing both meso and racemic donor cations has a very similar crystal structure but crystallising in the monoclinic space group C2/c (β = 91.39°) with similar S⋯S interactions but a smaller activation energy of 0.15–0.17 eV. This is in contrast to previous families of this type where the disordered racemate has a larger activation energy than its enantiopure salts
Tris(oxamide dioxime-κ2 N,N′)nickel(II) sulfate pentahydrate
The asymmetric unit of the title compound, [Ni(C2H6N4O2)3]SO4·5H2O, contains two complex cations, two sulfate anions and ten lattice water molecules. In both independent cations, the central NiII ion adopts a distorted octahedral coordination involving six imino N atoms of three bidentate oxamide dioxime ligands. The bulk structure is achieved by a three-dimensional network of O—H⋯O and N—H⋯O hydrogen bonds which interlink the ionic partners and some water molecules in such a manner that the lattice framework thus formed defines channels parallel to [100]. The other water molecules are lodged inside these channels. Two of the ten water molecules in the asymmetric unit are disordered over three sites, in 0.356 (3):0.324 (5):0.320 (5) and 0.247 (3):0.293 (6):0.460 (6) occupancy ratios, and one O atom of a sulfate ion is also disordered over two sites, with occupancies of 0.621 (5) and 0.379 (5)
Current status of the CLIO project
CLIO (Cryogenic Laser Interferometer Observatory) is a Japanese gravitational
wave detector project. One of the main purposes of CLIO is to demonstrate
thermal-noise suppression by cooling mirrors for a future Japanese project,
LCGT (Large-scale Cryogenic Gravitational Telescope). The CLIO site is in
Kamioka mine, as is LCGT. The progress of CLIO between 2005 and 2007 (room- and
cryogenic-temperature experiments) is introduced in this article. In a
room-temperature experiment, we made efforts to improve the sensitivity. The
current best sensitivity at 300 K is about
around 400 Hz. Below 20 Hz, the strain (not displacement) sensitivity is
comparable to that of LIGO, although the baselines of CLIO are 40-times shorter
(CLIO: 100m, LIGO: 4km). This is because seismic noise is extremely small in
Kamioka mine. We operated the interferometer at room temperature for
gravitational wave observations. We obtained 86 hours of data. In the cryogenic
experiment, it was confirmed that the mirrors were sufficiently cooled (14 K).
However, we found that the radiation shield ducts transferred 300K radiation
into the cryostat more effectively than we had expected. We observed that noise
caused by pure aluminum wires to suspend a mirror was suppressed by cooling the
mirror.Comment: 8 pages, 9 figures. Amaldi7 proceedings, J. Phys.: Conf. Ser.
(accepted
Search for continuous gravitational waves from PSR J0835-4510 using CLIO data
We search for continuous gravitational waves from PSR J0835-4510 at twice its rotational frequency using CLIO (Cryogenic Laser Interferometric Observatory) in the Kamioka mine. In this search, we use data from an observational run during 12–28 February 2007. We give a brief description of the methods used in this search. We obtain an upper limit on gravitational wave amplitude for PSR J0835-4510 as h0(UL) = 5.3 × 10−20 with 99.4% confidence level
Current status of Japanese detectors
Current status of TAMA and CLIO detectors in Japan is reported in this
article. These two interferometric gravitational-wave detectors are being
developed for the large cryogenic gravitational wave telescope (LCGT) which is
a future plan for detecting gravitational wave signals at least once per year.
TAMA300 is being upgraded to improve the sensitivity in low frequency region
after the last observation experiment in 2004. To reduce the seismic noises, we
are installing new seismic isolation system, which is called TAMA Seismic
Attenuation System, for the four test masses. We confirmed stable mass locks of
a cavity and improvements of length and angular fluctuations by using two SASs.
We are currently optimizing the performance of the third and fourth SASs. We
continue TAMA300 operation and R&D studies for LCGT. Next data taking in the
summer of 2007 is planned.
CLIO is a 100-m baseline length prototype detector for LCGT to investigate
interferometer performance in cryogenic condition. The key features of CLIO are
that it locates Kamioka underground site for low seismic noise level, and
adopts cryogenic Sapphire mirrors for low thermal noise level. The first
operation of the cryogenic interferometer was successfully demonstrated in
February of 2006. Current sensitivity at room temperature is close to the
target sensitivity within a factor of 4. Several observation experiments at
room temperature have been done. Once the displacement noise reaches at thermal
noise level of room temperature, its improvement by cooling test mass mirrors
should be demonstrated.Comment: 6 pages, 5 figures, Proceedings of GWDAW-1
Middle-Field Cusp Singularities in the Magnetization Process of One-Dimensional Quantum Antiferromagnets
We study the zero-temperature magnetization process (M-H curve) of
one-dimensional quantum antiferromagnets using a variant of the density-matrix
renormalization group method. For both the S=1/2 zig-zag spin ladder and the
S=1 bilinear-biquadratic chain, we find clear cusp-type singularities in the
middle-field region of the M-H curve. These singularities are successfully
explained in terms of the double-minimum shape of the energy dispersion of the
low-lying excitations. For the S=1/2 zig-zag spin ladder, we find that the cusp
formation accompanies the Fermi-liquid to non-Fermi-liquid transition.Comment: 4 pages, RevTeX, 3 figures, some mistakes in references are correcte
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