535 research outputs found
Surface Bound States in n-band Systems with Quasiclassical Approach
We discuss the tunneling spectroscopy at a surface in multi-band systems such
as Fe-based superconductors with the use of the quasiclassical approach. We
extend the single-band method by Matsumoto and Shiba [J. Phys. Soc. Jpn. 64,
1703 (1995)] into -band systems (). We show that the appearance
condition of the zero-bias conductance peak does not depend on details of the
pair-potential anisotropy, but it depends on details of the normal state
properties in the case of fully-gapped superconductors. The surface density of
states in a two-band superconductor is presented as a simplest application. The
quasiclassical approach enables us to calculate readily the surface-angular
dependence of the tunneling spectroscopy.Comment: 9 pages, 7 figures; References and Discussions update
Millimeter- and Submillimeter-Wave Observations of the OMC-2/3 Region. III. An Extensive Survey for Molecular Outflows
Using the ASTE 10 m submillimeter telescope and the 1.4 m Infrared Survey
Facility (IRSF), we performed an extensive outflow survey in the Orion
Molecular Cloud -2 and -3 region. Our survey, which includes 41 potential
star-forming sites, has been newly compiled using multi-wavelength data based
on millimeter- and submillimeter-continuum observations as well as radio
continuum observations. From the CO (3-2) observations performed with the ASTE
10 m telescope, we detected 14 CO molecular outflows, seven of which were newly
identified. This higher detection rate, as compared to previous CO (1-0)
results in the same region, suggests that CO (3-2) may be a better outflow
tracer. Physical properties of these outflows and their possible driving
sources were derived. Derived parameters were compared with those of CO
outflows in low- and high-mass starforming regions. We show that the CO outflow
momentum correlates with the bolometric luminosity of the driving source and
with the envelope mass, regardless of the mass of the driving sources. In
addition to these CO outflows, seven sources having NIR features suggestive of
outflows were also identified.Comment: Accepted to Astrophysical Journal, high resolution images at
http://www.asiaa.sinica.edu.tw/~satoko_t/papers/ms.ST.pd
Direct, Continuous Monitoring of Air Pollution by Transgenic Sensor Mice Responsive to Halogenated and Polycyclic Aromatic Hydrocarbons
BACKGROUND: The aryl hydrocarbon receptor (AhR, also called the dioxin receptor) plays crucial roles in toxicologic responses of animals to environmental pollutants, especially to halogenated and polycyclic aromatic hydrocarbons. To achieve direct, continuous risk assessment of air pollution using biological systems, we generated transgenic sensor mice that produce secreted alkaline phosphatase (SEAP) under the control of AhR. METHODS: To characterize responses of the mice to AhR agonists, sensor mice were orally administered 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 3-methylcholanthrene (3MC), benzo[a]pyrene (B[a]P), or β-naphthoflavone (BNF), and serum levels of SEAP were evaluated. To monitor air pollution caused by cigarette smoke, we placed the mice each day in an experimental smoking room, and evaluated activity of serum SEAP for up to 4 days. Activation of AhR in individual organs was also examined by reverse transcription–polymerase chain reaction (RT-PCR) analysis of SEAP. RESULTS: In response to oral exposure to TCDD, sensor mice exhibited dramatic and sustained activation of AhR. The mice also responded sensitively to 3MC, B[a]P, and BNF. Activation of AhR was dose dependent, and the liver was identified as the main responding organ. After exposure to the smoking environment, sensor mice consistently exhibited transient, reversible activation of AhR. RT-PCR analysis of SEAP revealed that activation of AhR occurred predominantly in the lung. CONCLUSION: We are the first laboratory to demonstrate successfully direct, comprehensive monitoring of air pollution using genetically engineered mammals. The established system would be useful for real risk assessment of halogenated and polycyclic aromatic hydrocarbons in the air, especially in smoking environments. KEY WORDS: aromatic hydrocarbon, aryl hydrocarbon receptor (AhR), cigarette smoke, dioxinresponsive element (DRE), secreted alkaline phosphatase (SEAP), transgenic mouse. Enviro
Symmetric Linear Backlund Transformation for Discrete BKP and DKP equation
Proper lattices for the discrete BKP and the discrete DKP equaitons are
determined. Linear B\"acklund transformation equations for the discrete BKP and
the DKP equations are constructed, which possesses the lattice symmetries and
generate auto-B\"acklund transformationsComment: 18 pages,3 figure
Diminishing returns and tradeoffs constrain the laboratory optimization of an enzyme
Optimization processes, such as evolution, are constrained by diminishing returns - the closer the optimum, the smaller the benefit per mutation, and by tradeoffs - improvement of one property at the cost of others. However, the magnitude and molecular basis of these parameters, and their effect on evolutionary transitions, remain unknown. Here we pursue a complete functional transition of an enzyme with a >109-fold change in the enzyme's selectivity using laboratory evolution. We observed strong diminishing returns, with the initial mutations conferring >25-fold higher improvements than later ones, and asymmetric tradeoffs whereby the gain/loss ratio of the new/old activity decreased 400-fold from the beginning of the trajectory to its end. We describe the molecular basis for these phenomena and suggest they have an important role in shaping natural proteins. These findings also suggest that the catalytic efficiency and specificity of many natural enzymes may be far from their optimum
Metamorphic Evolution of Garnet-bearing Epidote-Barroisite Schist From the Meratus Complex in South Kalimantan, Indonesia
DOI:10.17014/ijog.2.3.139-156This paper presents metamorphic evolution of metamorphic rocks from the Meratus Complex in South Kalimantan, Indonesia. Eight varieties of metamorphic rocks samples from this location, which are garnet-bearing epidote-barroisite schist, epidote-barroisite schist, glaucophane-quartz schist, garnet-muscovite schist, actinolite-talc schist, epidote schist, muscovite schist, and serpentinite, were investigated in detail its petrological and mineralogical characteristics by using polarization microscope and electron probe micro analyzer (EPMA). Furthermore, the pressure-temperature path of garnet-bearing epidote-barroisite schist was estimated by using mineral parageneses, reaction textures, and mineral chemistries to assess the metamorphic history. The primary stage of this rock might be represented by the assemblage of glaucophane + epidote + titanite ± paragonite. The assemblage yields 1.7 - 1.0 GPa in assumed temperature of 300 - 550 °C, which is interpreted as maximum pressure limit of prograde stage. The peak P-T condition estimated on the basis of the equilibrium of garnet rim, barroisite, phengite, epidote, and quartz, yields 547 - 690 °C and 1.1 - 1.5 GPa on the albite epidote amphibolite-facies that correspond to the depth of 38 - 50 km. The retrograde stage was presented by changing mineral compositions of amphiboles from the Si-rich barroisite to the actinolite, which lies near 0.5 GPa at 350 °C. It could be concluded that metamorphic rocks from the Meratus Complex experienced low-temperature and high-pressure conditions (blueschist-facies) prior to the peak metamorphism of the epidote amphibolite-facies. The subduction environments in Meratus Complex during Cretaceous should be responsible for this metamorphic condition
Field angle dependence of the zero-energy density of states in unconventional superconductors: analysis of the borocarbide superconductor YNi2B2C
We investigate the field-angle-dependent zero-energy density of states for
YNi2B2C with using realistic Fermi surfaces obtained by band calculations. Both
the 17th and 18th bands are taken into account. For calculating the oscillating
density of states, we adopt the Kramer-Pesch approximation, which is found to
improve accuracy in the oscillation amplitude. We show that superconducting gap
structure determined by analyzing STM experiments is consistent with thermal
transport and heat capacity measurements.Comment: 4 pages, 1 figure, 25th international conference on Low Temperature
Physics (Amsterdam, The Netherlands, August 6-13 2008) LT1597, to be
published in Journal of Physics: Conference Series 200
A Symmetric Generalization of Linear B\"acklund Transformation associated with the Hirota Bilinear Difference Equation
The Hirota bilinear difference equation is generalized to discrete space of
arbitrary dimension. Solutions to the nonlinear difference equations can be
obtained via B\"acklund transformation of the corresponding linear problems.Comment: Latex, 12 pages, 1 figur
Herbig Ae/Be Stars in the Magellanic Bridge
We have found Herbig Ae/Be star candidates in the western region of the
Magellanic Bridge. Using the near infrared camera SIRIUS and the 1.4 m
telescope IRSF, we surveyed about 3.0 deg x 1.3 deg (24 deg < RA < 36 deg, -75
deg < Dec. < -73.7 deg) in the J, H, and Ks bands. On the basis of colors and
magnitudes, about 200 Herbig Ae/Be star candidates are selected. Considering
the contaminations by miscellaneous sources such as foreground stars and
early-type dwarfs in the Magellanic Bridge, we estimate that about 80 (about
40%) of the candidates are likely to be Herbig Ae/Be stars. We also found one
concentration of the candidates at the young star cluster NGC 796, strongly
suggesting the existence of pre-main-sequence (PMS) stars in the Magellanic
Bridge. This is the first detection of PMS star candidates in the Magellanic
Bridge, and if they are genuine PMS stars, this could be direct evidence of
recent star formation. However, the estimate of the number of Herbig Ae/Be
stars depends on the fraction of classical Be stars, and thus a more precise
determination of the Be star fraction or observations to differentiate between
the Herbig Ae/Be stars and classical Be stars are required.Comment: 22 pages, 6 figures. Accepted for publication in Ap
Elementary vortex pinning potential in a chiral p-wave superconductor
The elementary vortex pinning potential is studied in a chiral p-wave
superconductor with a pairing d=z(k_x + i k_y) on the basis of the
quasiclassical theory of superconductivity. An analytical investigation and
numerical results are presented to show that the vortex pinning potential is
dependent on whether the vorticity and chirality are parallel or antiparallel.
Mutual cancellation of the vorticity and chirality around a vortex is
physically crucial to the effect of the pinning center inside the vortex core.Comment: 4 pages, 4 figures include
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