1,665 research outputs found
An Unbiased Survey for Molecular Clouds in the Southern Galactic Warp
We have made an unbiased survey for molecular clouds in the Galactic Warp.
This survey, covering an area of 56 square degrees at l = 252 deg to 266 deg
and b = -5 deg to -1 deg, has revealed 70 molecular clouds, while only 6 clouds
were previously known in the region. The number of molecular clouds is, then,
an order of magnitude greater than previously known in this sector at R > 14.5
kpc. The mass of the clouds is in a range from 7.8x10(2) Mo to 8.4x10(4) Mo,
significantly less than the most massive giant molecular clouds in the inner
disk, ~10(6) Mo, while the cloud mass spectrum characterized by a power law is
basically similar to other parts of the Galaxy. The X factor, N(H2)/Wco(12CO),
derived from the molecular clouds in the Warp is estimated to be 3.5(+/-1.8)
times larger than that in the inner disk. The total molecular mass in the Warp
is estimated as 7.3x10(5) Mo, and total mass in the far-outer Galaxy (R > 14.5
kpc) can be estimated as 2x10(7) Mo. The spatial correlation between the CO and
HI distribution appears fairly good, and the mass of the molecular gas is about
1% of that of the atomic gas in the far-outer Galaxy. This ratio is similar to
that in the interarm but is ten times smaller than those of the spiral arms.
Only 6 of the 70 Warp clouds show signs of star formation at the IRAS
sensitivity and star formation efficiency for high-mass stars in the Warp is
found to be smaller than those in other molecular clouds in the Galaxy.Comment: 29 pages, including 12 (pages of) figures, accepted for PASJ, and
will be published in PASJ Vol.57, No.6. Tables and color-figures are
available on-line:
http://www.a.phys.nagoya-u.ac.jp/~masa/study/nakagawa_etal2005_warp.pd
Photodarkening of amorphous selenium under high pressure
The photodarkening phenomena of amorphous Se have been studied by the optical absorption coefficient, sound velocity and attenuation measurements. The light illumination at low temperatures induces the photodarkening, and the photodarkened state is completely recovered by annealing near 306 K corresponding to the glass transition temperature. The photodarkening is enhanced by application of pressure. The sound velocity decreases and the sound attenuation increases by the illumination at low temperature. These suggest that a structural disorder increases in the photodarkened state. Three stages are observed for the recovery process of the photodarkened specimen. The photodarkening and the recovery process are discussed on the basis of VAP (valence alternative pair) model.<br /
Electronic state around vortex in a two-band superconductor
Based on the quasiclassical theory, we investigate the vortex state in a
two-band superconductor with a small gap on a three dimensional Fermi surface
and a large gap on a quasi-two dimensional one, as in MgB_2. The field
dependence of zero-energy density of states is compared for fields parallel and
perpendicular to the ab plane, and the anisotropy of the vortex core shape is
discussed for a parallel field. The Fermi surface geometry of two-bands,
combining the effect of the normal-like electronic state on the small gap band
at high fields, produces characteristic behavior in the anisotropy of c- and
ab-directions.Comment: 6 pages, 6 figures, to appear in Phys. Rev.
Precise Estimation of Cosmological Parameters Using a More Accurate Likelihood Function
The estimation of cosmological parameters from a given data set requires a
construction of a likelihood function which, in general, has a complicated
functional form. We adopt a Gaussian copula and constructed a copula likelihood
function for the convergence power spectrum from a weak lensing survey. We show
that the parameter estimation based on the Gaussian likelihood erroneously
introduces a systematic shift in the confidence region, in particular for a
parameter of the dark energy equation of state w. Thus, the copula likelihood
should be used in future cosmological observations.Comment: 5 pages, 3 figures. Maches version published by the Physical Review
Letter
Vortex state in double transition superconductors
Novel vortex phase and nature of double transition field are investigated by
two-component Ginzburg-Landau theory in a situation where fourfold-twofold
symmetric superconducting double transition occurs. The deformation from 60
degree triangular vortex lattice and a possibility of the vortex sheet
structure are discussed. In the presence of the gradient coupling, the
transition changes to a crossover at finite fields. These characters are
important to identify the multiple superconducting phase in PrOs_4_Sb_12.Comment: 4 pages, 4 figures, to appear in Phys. Rev. Let
Соотношение путей углеводного синтеза при введении свободных и фосфорилированных сахаров в листья картофеля
Показано, что регуляция путей биосинтеза углеводов может осуществляться через изменение концентрации промежуточных и конечных метаболитов. При этом одним из факторов, регулирующих направленность синтеза углеводов, является активность АДФГ- и УДФГ-пирофосфорилаз. По-видимому, регуляция работы этих ферментов может осуществляться низкомолекулярными метаболитами по принципу обратной связи
Thermal Conductivity in the Bose-Einstein Condensed State of Triplons in the Bond-Alternating Spin-Chain System Pb2V3O9
In order to clarify the origin of the enhancement of the thermal conductivity
in the Bose-Einstein Condensed (BEC) state of field-induced triplons, we have
measured the thermal conductivity along the [101] direction parallel to
spin-chains, , and perpendicular to spin-chains,
, of the S=1/2 bond-alternating spin-chain system Pb2V3O9
in magnetic fields up to 14 T. With increasing field at 3 K, it has been found
that both and are suppressed in the
gapped normal state in low fields. In the BEC state of field-induced triplons
in high fields, on the other hand, is enhanced with
increasing field, while is suppressed. That is, the
thermal conductivity along the direction, where the magnetic interaction is
strong, is markedly enhanced in the BEC state. Accordingly, our results suggest
that the enhancement of in the BEC state is caused by the
enhancement of the thermal conductivity due to triplons on the basis of the
two-fluid model, as in the case of the superfluid state of liquid 4He.Comment: 5 pages, 3 figure
Extremely anisotropic suppression of huge enhancement of electrical resistivity by magnetic field in α-R2S3 (R = Sm, Dy).
The electrical resistivity ρ and magnetization M of α-R 2S3 (R = Sm, Dy) single crystals have been measured in various magnetic fields lying in the ac-plane of an orthorhombic crystal structure. The measurements have been carried out by rotating the single crystals around the b-axis (being set parallel to a horizontal direction), corresponding to the longitudinal direction of needle-shaped single crystals, in vertical magnetic fields. The electrical resistivity under no magnetic field shows huge enhancement in a narrow temperature range around the successive magnetic transition temperatures, as reported previously. Such enhancement is suppressed rapidly by applying a magnetic field, which has been clearly seen as diminishing of the ρ(T) peak. The magnetic field along the easy magnetization axis; H easy, moves the ρ(T) peak toward higher temperature with diminishing it, while the magnetic field along the hard magnetization axis; H hard, moves it to lower temperature. The suppression effect is extremely anisotropic for the orientation of the magnetic field lying in the ac-plane. It has been concluded that H easy suppresses the ρ enhancement most strongly. The suppression effect under H easy is more than 200 times larger at least in some cases than that under H hard
Charmed meson spectra and decay constants with one-loop improved relativistic heavy quark action
We calculate charmed meson spectra and decay constants in lattice QCD
employing one-loop improved heavy quark action and axial-vector
currents. In quenched simulations at fm with the plaquette gauge
action as well as a renormalization-group improved one, it is shown that the
deviation from the continuum dispersion relation and the violation of
space-time symmetry for the pseudoscalar meson decay constants are
substantially reduced, once the improvement is applied. Preliminary
results with two flavors of dynamical quarks are also presented.Comment: 3 pages, 4 figure, talk presented at Lattice2004(heavy), Fermilab,
June 21-26, 200
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