165 research outputs found
Open Semiclassical Strings and Long Defect Operators in AdS/dCFT Correspondence
We consider defect composite operators in a defect superconformal field
theory obtained by inserting an AdS_4 x S^2-brane in the AdS_5 x S^5
background. The one-loop dilatation operator for the scalar sector is
represented by an integrable open spin chain. We give a description to
construct coherent states for the open spin chain. Then, by evaluating the
expectation value of the Hamiltonian with the coherent states in a long
operator limit, a Landau-Lifshitz type of sigma model action is obtained. This
action is also derived from the string action and hence we find a complete
agreement in both SYM and string sides. We see that an SO(3)_H pulsating string
solution is included in the action and its energy completely agrees with the
result calculated in a different method. In addition, we argue that our
procedure would be applicable to other AdS-brane cases.Comment: 22 pages, 1 figure, LaTeX, minor corrections and references added.
v3) some new results added. shortened and accepted version in PR
Optically tuned dimensionality crossover in photocarrier-doped SrTiO: onset of weak localization
We report magnetotransport properties of photogenerated electrons in undoped
SrTiO single crystals under ultraviolet illumination down to 2 K. By tuning
the light intensity, the steady state carrier density can be controlled, while
tuning the wavelength controls the effective electronic thickness by modulating
the optical penetration depth. At short wavelengths, when the sheet conductance
is close to the two-dimensional Mott minimum conductivity we have observed
critical behavior characteristic of weak localization. Negative
magnetoresistance at low magnetic field is highly anisotropic, indicating
quasi-two-dimensional electronic transport. The high mobility of photogenerated
electrons in SrTiO allows continuous tuning of the effective electronic
dimensionality by photoexcitation.Comment: 7 pages, 7 figure
Metal-insulator Crossover Behavior at the Surface of NiS_2
We have performed a detailed high-resolution electron spectroscopic
investigation of NiS and related Se-substituted compounds
NiSSe, which are known to be gapped insulators in the bulk at all
temperatures. A large spectral weight at the Fermi energy of the room
temperature spectrum, in conjunction with the extreme surface sensitivity of
the experimental probe, however, suggests that the surface layer is metallic at
300 K. Interestingly, the evolution of the spectral function with decreasing
temperature is characterized by a continuous depletion of the single-particle
spectral weight at the Fermi energy and the development of a gap-like structure
below a characteristic temperature, providing evidence for a metal-insulator
crossover behavior at the surfaces of NiS and of related compounds. These
results provide a consistent description of the unusual transport properties
observed in these systems.Comment: 12 pages, 3 figure
Serial optical coherence microscopy for label-free volumetric histopathology
The observation of histopathology using optical microscope is an essential procedure for examination of tissue biopsies or surgically excised specimens in biological and clinical laboratories. However, slide-based microscopic pathology is not suitable for visualizing the large-scale tissue and native 3D organ structure due to its sampling limitation and shallow imaging depth. Here, we demonstrate serial optical coherence microscopy (SOCM) technique that offers label-free, high-throughput, and large-volume imaging of ex vivo mouse organs. A 3D histopathology of whole mouse brain and kidney including blood vessel structure is reconstructed by deep tissue optical imaging in serial sectioning techniques. Our results demonstrate that SOCM has unique advantages as it can visualize both native 3D structures and quantitative regional volume without introduction of any contrast agents
Periodic Anderson model with degenerate orbitals: linearized dynamical mean field theory approach
We investigate a multi-orbital extension of the periodic Anderson model with
particular emphasis on electron correlations including orbital fluctuations. By
means of a linearized version of the dynamical mean-field theory, we compute
the renormalization factor, the density of states, the spectral gap and the
local correlation functions for a given set of the intra- and inter-orbital
Coulomb interactions as well as the Hund coupling. It is found that when a
certain condition is met for the intra- and inter-orbital interactions for
electrons, orbital fluctuations are enhanced, thereby enlarging the Kondo
insulating gap. This effect is suppressed in the presence of the Hund coupling.
We also clarify how the Kondo insulator is continuously changed to the Mott
insulator when electron correlations among conduction electrons are increased.Comment: 7 pages, 10 figure
Integrable open spin chains from giant gravitons
We prove that in the presence of a maximal giant graviton state in N=4 SYM,
the states dual to open strings attached to the giant graviton give rise to an
PSU(2,2|4) open spin chain model with integrable boundary conditions in the
SO(6) sector of the spin chain to one loop order.Comment: 18 pages, 2 figures, uses JHEP
Neuroscience in the third dimension: shedding new light on the brain with tissue clearing
Modern microwave methods in solid state inorganic materials chemistry: from fundamentals to manufacturing
No abstract available
Prolonged Mechanical Ventilation Induces Cell Cycle Arrest in Newborn Rat Lung
Rationale: The molecular mechanism(s) by which mechanical ventilation disrupts alveolar development, a hallmark of bronchopulmonary dysplasia, is unknown. Objective: To determine the effect of 24 h of mechanical ventilation on lung cell cycle regulators, cell proliferation and alveolar formation in newborn rats. Methods: Seven-day old rats were ventilated with room air for 8, 12 and 24 h using relatively moderate tidal volumes (8.5 mL.kg-1). Measurement and Main Results: Ventilation for 24 h (h) decreased the number of elastin-positive secondary crests and increased the mean linear intercept, indicating arrest of alveolar development. Proliferation (assessed by BrdU incorporation) was halved after 12 h of ventilation and completely arrested after 24 h. Cyclin D1 and E1 mRNA and protein levels were decreased after 8-24 h of ventilation, while that of p27Kip1 was significantly increased. Mechanical ventilation for 24 h also increased levels of p57Kip2, decreased that of p16INK4a, while the levels of p21Waf/Cip1 and p15INK4b were unchanged. Increased p27Ki
Imaging the mammary gland and mammary tumours in 3D: optical tissue clearing and immunofluorescence methods
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