Analytical and numerical evaluation of the Debye and Meissner masses in dense neutral three-flavor quark matter

We calculate the Debye and Meissner masses and investigate chromomagnetic instability associated with the gapless color superconducting phase changing the strange quark mass $M_s$ and the temperature $T$. Based on the analytical study, we develop a computational procedure to derive the screening masses numerically from curvatures of the thermodynamic potential. When the temperature is zero, from our numerical results for the Meissner masses, we find that instability occurs for $A_1$ and $A_2$ gluons entirely in the gapless color-flavor locked (gCFL) phase, while the Meissner masses are real for $A_4$, $A_5$, $A_6$, and $A_7$ until $M_s$ exceeds a certain value that is larger than the gCFL onset. We then handle mixing between color-diagonal gluons $A_3$, $A_8$, and photon $A_\gamma$, and clarify that, among three eigenvalues of the mass squared matrix, one remains positive, one is always zero because of an unbroken U(1)_\tilde{Q} symmetry, and one exhibits chromomagnetic instability in the gCFL region. We also examine the temperature effects that bring modifications into the Meissner masses. The instability found at large $M_s$ for $A_4$, $A_5$, $A_6$, and $A_7$ persists at finite $T$ into the $u$-quark color superconducting (uSC) phase which has $u$-$d$ and $s$-$u$ but no $d$-$s$ quark pairing and also into the two-flavor color superconducting (2SC) phase characterized by $u$-$d$ quark pairing only. The $A_1$ and $A_2$ instability also goes into the uSC phase, but the 2SC phase has no instability for $A_1$, $A_2$, and $A_3$. We map the unstable region for each gluon onto the phase diagram as a function of $M_s$ and $T$.Comment: 17 pages, 18 figure

Dynamics and Control of a Quasi-1D Spin System

We study experimentally a system comprised of linear chains of spin-1/2 nuclei that provides a test-bed for multi-body dynamics and quantum information processing. This system is a paradigm for a new class of quantum information devices that can perform particular tasks even without universal control of the whole quantum system. We investigate the extent of control achievable on the system with current experimental apparatus and methods to gain information on the system state, when full tomography is not possible and in any case highly inefficient

The explanation of unexpected temperature dependence of the muon catalysis in solid deuterium

It is shown that due to the smallness of the inelastic cross-section of the $d\mu$-atoms scattering in the crystal lattice at sufficiently low temperatures the $dd\mu$-mesomolecules formation from the upper state of the hyperfine structure $d\mu (F=3/2)$ starts earlier than the mesoatoms thermolization. It explains an approximate constancy of the $dd\mu$-mesomolecule formation rate in solid deuterium.Comment: 6 pages, 2 jpeg-figure

A novel type of proximity focusing RICH counter with multiple refractive index aerogel radiator

A proximity focusing ring imaging Cherenkov detector, with the radiator consisting of two or more aerogel layers of different refractive indices, has been tested in 1-4 GeV/c pion beams at KEK. Essentially, a multiple refractive index aerogel radiator allows for an increase in Cherenkov photon yield on account of the increase in overall radiator thickness, while avoiding the simultaneous degradation in single photon angular resolution associated with the increased uncertainty of the emission point. With the refractive index of consecutive layers suitably increasing in the downstream direction, one may achieve overlapping of the Cherenkov rings from a single charged particle. In the opposite case of decreasing refractive index, one may obtain well separated rings. In the former combination an approximately 40% increase in photon yield is accompanied with just a minor degradation in single photon angular resolution. The impact of this improvement on the pion/kaon separation at the upgraded Belle detector is discussed.Comment: submitted to Nucl. Instr. Meth.

Exchange Interactions and High-Energy Spin States in Mn_12-acetate

We perform inelastic neutron scattering measurements on the molecular nanomagnet Mn_12-acetate to measure the excitation spectrum up to 45meV (500K). We isolate magnetic excitations in two groups at 5-6.5meV (60-75K) and 8-10.5meV (95-120K), with higher levels appearing only at 27meV (310K) and 31meV (360K). From a detailed characterization of the transition peaks we show that all of the low-energy modes appear to be separate S = 9 excitations above the S = 10 ground state, with the peak at 27meV (310K) corresponding to the first S = 11 excitation. We consider a general model for the four exchange interaction parameters of the molecule. The static susceptibility is computed by high-temperature series expansion and the energy spectrum, matrix elements and ground-state spin configuration by exact diagonalization. The theoretical results are matched with experimental observation by inclusion of cluster anisotropy parameters, revealing strong constraints on possible parameter sets. We conclude that only a model with dominant exchange couplings J_1 ~ J_2 ~ 5.5meV (65K) and small couplings J_3 ~ J_4 ~ 0.6meV (7K) is consistent with the experimental data.Comment: 17 pages, 12 figure

Fermi Surface of 3d^1 Perovskite CaVO3 Near the Mott Transition

We present a detailed de Haas van Alphen effect study of the perovskite CaVO3, offering an unprecedented test of electronic structure calculations in a 3d transition metal oxide. Our experimental and calculated Fermi surfaces are in good agreement -- but only if we ignore large orthorhombic distortions of the cubic perovskite structure. Subtle discrepancies may shed light on an apparent conflict between the low energy properties of CaVO3, which are those of a simple metal, and high energy probes which reveal strong correlations that place CaVO3 on the verge of a metal-insulator transition.Comment: 4 pages, 4 figures (REVTeX

Interannual variation in the fine-mode MODIS aerosol optical depth and its relationship to the changes in sulfur dioxide emissions in China between 2000 and 2010

Anthropogenic SO<sub>2</sub> emissions increased alongside economic development in China at a rate of 12.7% yr<sup>−1</sup> from 2000 to 2005. However, under new Chinese government policy, SO<sub>2</sub> emissions declined by 3.9% yr<sup>−1</sup> between 2005 and 2009. Between 2000 and 2010, we found that the variability in the fine-mode (submicron) aerosol optical depth (AOD) over the oceans adjacent to East Asia increased by 3–8% yr<sup>−1</sup> to a peak around 2005–2006 and subsequently decreased by 2–7% yr<sup>−1</sup>, based on observations by the Moderate Resolution Imaging Spectroradiometer (MODIS) on board NASA's Terra satellite and simulations by a chemical transport model. This trend is consistent with ground-based observations of aerosol particles at a mountainous background observation site in central Japan. These fluctuations in SO<sub>2</sub> emission intensity and fine-mode AOD are thought to reflect the widespread installation of fuel-gas desulfurization (FGD) devices in power plants in China, because aerosol sulfate is a major determinant of the fine-mode AOD in East Asia. Using a chemical transport model, we confirmed that the contribution of particulate sulfate to the fine-mode AOD is more than 70% of the annual mean and that the abovementioned fluctuation in fine-mode AOD is caused mainly by changes in SO<sub>2</sub> emission rather than by other factors such as varying meteorological conditions in East Asia. A strong correlation was also found between satellite-retrieved SO<sub>2</sub> vertical column density and bottom-up SO<sub>2</sub> emissions, both of which were also consistent with observed fine-mode AOD trends. We propose a simplified approach for evaluating changes in SO<sub>2</sub> emissions in China, combining the use of modeled sensitivity coefficients that describe the variation of fine-mode AOD with changes in SO<sub>2</sub> emissions and satellite retrieval. Satellite measurements of fine-mode AOD above the Sea of Japan marked a 4.1% yr<sup>−1</sup> decline between 2007 and 2010, which corresponded to the 9% yr<sup>−1</sup> decline in SO<sub>2</sub> emissions from China during the same period

RhoJ integrates attractive and repulsive cues in directional migration of endothelial cells

During angiogenesis, VEGF acts as an attractive cue for endothelial cells (ECs), while Sema3E mediates repulsive cues. Here, we show that the small GTPase RhoJ integrates these opposing signals in directional EC migration. In the GTP-bound state, RhoJ interacts with the cytoplasmic domain of PlexinD1. Upon Sema3E stimulation, RhoJ released from PlexinD1 induces cell contraction. PlexinD1-bound RhoJ further facilitates Sema3E-induced PlexinD1-VEGFR2 association, VEGFR2 transphosphorylation at Y1214, and p38 MAPK activation, leading to reverse EC migration. Upon VEGF stimulation, RhoJ is required for the formation of the holoreceptor complex comprising VEGFR2, PlexinD1, and neuropilin-1, thereby preventing degradation of internalized VEGFR2, prolonging downstream signal transductions via PLCγ, Erk, and Akt, and promoting forward EC migration. After conversion to the GDP-bound state, RhoJ shifts from PlexinD1 to VEGFR2, which then terminates the VEGFR2 signals. RhoJ deficiency in ECs efficiently suppressed aberrant angiogenesis in ischemic retina. These findings suggest that distinct Rho GTPases may act as context-dependent integrators of chemotactic cues in directional cell migration and may serve as candidate therapeutic targets to manipulate cell motility in disease or tissue regeneration

Astrometric Control of the Inertiality of the Hipparcos Catalog

Based on the most complete list of the results of an individual comparison of the proper motions for stars of various programs common to the Hipparcos catalog, each of which is an independent realization of the inertial reference frame with regard to stellar proper motions, we redetermined the vector $\omega$ of residual rotation of the ICRS system relative to the extragalactic reference frame. The equatorial components of this vector were found to be the following: $\omega_x = +0.04\pm 0.15$ mas yr$^{-1}$, $\omega_y = +0.18\pm 0.12$ mas yr$^{-1}$, and $\omega_z = -0.35\pm 0.09$ mas yr$^{-1}$.Comment: 8 pages, 1 figur