170 research outputs found
Schwarzschild radius from Monte Carlo calculation of the Wilson loop in supersymmetric matrix quantum mechanics
In the string/gauge duality it is important to understand how the space-time
geometry is encoded in gauge theory observables. We address this issue in the
case of the D0-brane system at finite temperature T. Based on the duality, the
temporal Wilson loop operator W in gauge theory is expected to contain the
information of the Schwarzschild radius R_{Sch} of the dual black hole geometry
as log = R_{Sch} / (2 pi alpha' T). This translates to the power-law
behavior log = 1.89 (T/lambda^{1/3})^{-3/5}, where lambda is the 't Hooft
coupling constant. We calculate the Wilson loop on the gauge theory side in the
strongly coupled regime by performing Monte Carlo simulation of supersymmetric
matrix quantum mechanics with 16 supercharges. The results reproduce the
expected power-law behavior up to a constant shift, which is explainable as
alpha' corrections on the gravity side.Comment: REVTeX4, 4 pages, 1 figur
Anisotropic uniaxial pressure response of the Mott insulator Ca2RuO4
We have investigated the in-plane uniaxial pressure effect on the
antiferromagnetic Mott insulator Ca2RuO4 from resistivity and magnetization
measurements. We succeeded in inducing the ferromagnetic metallic phase at
lower critical pressure than by hydrostatic pressure, indicating that the
flattening distortion of the RuO6 octahedra is more easily released under
in-plane uniaxial pressure. We also found a striking in-plane anisotropy in the
pressure responses of various magnetic phases: Although the magnetization
increases monotonically with pressure diagonal to the orthorhombic principal
axes, the magnetization exhibits peculiar dependence on pressure along the
in-plane orthorhombic principal axes. This peculiar dependence can be explained
by a qualitative difference between the uniaxial pressure effects along the
orthorhombic a and b axes, as well as by the presence of twin domain
structures.Comment: Accepted for publication in Phys. Rev.
Putting M theory on a computer
We propose a non-lattice simulation for studying supersymmetric matrix
quantum mechanics in a non-perturbative manner. In particular, our method
enables us to put M theory on a computer based on its matrix formulation
proposed by Banks, Fischler, Shenker and Susskind. Here we present Monte Carlo
results of the same matrix model but in a different parameter region, which
corresponds to the 't Hooft large-N limit at finite temperature. In the strong
coupling limit the model has a dual description in terms of the N D0-brane
solution in 10d type IIA supergravity. Our results provide highly nontrivial
evidences for the conjectured duality. In particular, the energy (and hence the
entropy) of the non-extremal black hole has been reproduced by solving directly
the strongly coupled dynamics of the D0-brane effective theory.Comment: 7 pages, 3 figures, talk presented at the XXV International Symposium
on Lattice Field Theory, July 30 - August 4 2007, Regensburg, German
Ground-state properties of neutron-rich Mg isotopes
We analyze recently-measured total reaction cross sections for 24-38Mg
isotopes incident on 12C targets at 240 MeV/nucleon by using the folding model
and antisymmetrized molecular dynamics(AMD). The folding model well reproduces
the measured reaction cross sections, when the projectile densities are
evaluated by the deformed Woods-Saxon (def-WS) model with AMD deformation.
Matter radii of 24-38Mg are then deduced from the measured reaction cross
sections by fine-tuning the parameters of the def-WS model. The deduced matter
radii are largely enhanced by nuclear deformation. Fully-microscopic AMD
calculations with no free parameter well reproduce the deduced matter radii for
24-36Mg, but still considerably underestimate them for 37,38Mg. The large
matter radii suggest that 37,38Mg are candidates for deformed halo nucleus. AMD
also reproduces other existing measured ground-state properties (spin-parity,
total binding energy, and one-neutron separation energy) of Mg isotopes.
Neutron-number (N) dependence of deformation parameter is predicted by AMD.
Large deformation is seen from 31Mg with N = 19 to a drip-line nucleus 40Mg
with N = 28, indicating that both the N = 20 and 28 magicities disappear. N
dependence of neutron skin thickness is also predicted by AMD.Comment: 15 pages, 13 figures, to be published in Phys. Rev.
Vacuum-Assisted Closure (VAC) for Bilateral Severe Ischemic Foot after Revascularization: A Patient Report
The Vacuum-Assisted Closure (VAC) Therapy (KCI, San Antonio, TX) is a unique system that helps promote wound healing. We report a case of severe ischemic foot in which VAC therapy markedly improved wound healing. A 73-year-old man underwent left axillopopliteal bypass and left 3rd, 4th and 5th digital amputations for gangrene. Although his amputation stumps were complicated with methicillin-resistant Staphylococcus aureus (MRSA) infection, the stumps were successfully healed by VAC. He also had gangrene in his right 1st toe, which could not healed by VAC alone, and we performed right femoropopliteal bypass and right 1st digital amputation. The stump with MRSA infection was also successfully healed by VAC. Histopathologic examination revealed a lot of microvessels in the increased granulation tissue
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