1,451 research outputs found
The Role of Subsurface Flow Dynamic on Spatial and Temporal Variation of Water Chemistry in a Headwater Catchment
Variation of water chemistry does not merely occur due to in situ chemical process, but also transport process. The study was carried out to address the role of subsurface flow dynamic on spatial and temporal variation of water chemistry in a headwater catchment. Hydrometric and hydrochemistry measurements were done in transect with nested piezometers, tensiometers, and suction samplers at different depths across hillslope and riparian zone in a 5.2 ha first-order drainage of the Kawakami experimental basin, Nagano, Central Japan from August 2000 to August 2001. Spatial variation of solute concentration was defined by the standard deviation and coefficient of variation of the seasonal observed concentrations. Autocorrelation analysis was performed to define temporal variation of solute concentration. The results showed that spatial variation of water chemistry was mainly influenced by the variation of subsurface flow through the hillslope and riparian zone. Solute concentration in the deep riparian groundwater was almost three times higher than that in the hillslope segment. A prominent downward flow in deep riparian groundwater zone provided transport of solutes to the deeper layer. Time series analysis showed that in the deep riparian groundwater, Ca2+, Mg2+, SO42- and HCO3- concentrations underwent a random process, Na+ concentration of a random process superimposed by a trend process, and SiO2 of a random process superimposed by a periodic process. Near the riparian surface, SO42- concentration was composed of a random process superimposed by a periodic process, whereas other solutes were mainly in a random process. In the hillslope soil water, there was no trend observed for the Na+ concentration, but there were for Ca2+ and Mg2+. The magnitude and direction of subsurface flow across hillslope and riparian zone created transport and deposition processes that changed solute concentration spatially and temporally
Application of a novel method for subsequent evaluation of sinusoids and postsinusoidal venules after ischemia-reperfusion injury of rat liver
Although several intravital fluorescence microscopic studies demonstrated that microcirculatory derangement is induced during liver ischemia-reperfusion, these data were obtained from randomly selected microvascular areas and microvessels, Repeated observation of the identical microvessels has not been performed yet. Using a specially designed cover glass, it is now possible to relocate desired sites of observation repeatedly over the whole reperfusion time, The aim of this study was to determine the impact of reperfusion time on hepatic microvascular perfusion state. Twenty minutes of ischemia induced a significant decrease in sinusoidal perfusion rate (29.1 +/- 10.2%) as compared with baseline values (98.0 +/- 0.3%). At 30, 60, and 120 min of reperfusion, the percentage of perfused sinusoids recovered to 62.8 +/- 6.6, 67.5 +/- 5.7, and 77.2 +/- 5.4%. The number of stagnant leukocytes in the same sinusoids was 6.2 +/- 1.9/lobule at baseline and increased to 22.3 +/- 3.6/lobule at 120 min of reperfusion. The number of leukocytes adhering within postsinusoidal venules was 53.5 +/- 12.5/mm(2) before ischemia and increased to 414.2 +/- 62.5/mm(2) at 120 min of reperfusion. We have demonstrated that during 120 min of reperfusion, there was a steady increase in both sinusoidal and venular leukocyte adhesion along with an attenuation of the initially severely depressed sinusoidal perfusion. a no-reflow phenomenon at an early phase of reperfusion and subsequent reflow were proven
Invariance Violation Extends the Cosmic Ray Horizon ?
We postulate in the present paper that the energy-momentum relation is
modified for very high energy particles to violate Lorentz invariance and the
speed of photon is changed from the light velocity c. The violation effect is
amplified, in a sensitive way to detection, through the modified kinematical
constraints on the conservation of energy and momentum, in the absorption
process of gamma-rays colliding against photons of longer wavelengths and
converting into an electron-positron pair. For gamma-rays of energies higher
than 10 TeV, the minimum energy of the soft photons for the reaction and then
the absorption mean free path of gamma-rays are altered by orders of magnitude
from the ones conventionally estimated. Consideration is similarly applied to
high energy cosmic ray protons. The consequences may require the standard
assumptions on the maximum distance that very high energy radiation can travel
from to be revised.Comment: 14 pages, 1 figure, to be published in Ap J Letter
Dust in the Photospheric Environment II. Effect on the Near Infrared Spectra of L and T Dwarfs
We report an attempt to interpret the spectra of L and T dwarfs with the use
of the Unified Cloudy Model (UCM). For this purpose, we extend the grid of the
UCMs to the cases of log g = 4.5 and 5.5. The dust column density relative to
the gas column density in the observable photosphere is larger at the higher
gravities, and molecular line intensity is generally smaller at the higher
gravities. The overall spectral energy distributions (SEDs) are f_{J} < f_{H} <
f_{K} in middle and late L dwarfs, f_{J} f_{K} in early T dwarfs (L/T
transition objects), and finally f_{J} > f_{H} > f_{K} in middle and late T
dwarfs, where f_{J}, f_{H}, and f_{K} are the peak fluxes at J, H, and K bands,
respectively, in f_{nu} unit. This tendency is the opposite to what is expected
for the temperature effect, but can be accounted for as the effect of thin dust
clouds formed deep in the photosphere together with the effect of the gaseous
opacities including H_2 (CIA), H_2O, CH_4, and K I. Although the UCMs are
semi-empirical models based on a simple assumption that thin dust clouds form
in the region of T_{cr} < T < T_{cond} (T_{cr} = 1800K is an only empirical
parameter while T_{cond} about 2000K is fixed by the thermodynamical data), the
major observations including the overall SEDs as well as the strengths of the
major spectral features are consistently accounted for throughout L and T
dwarfs. In view of the formidable complexities of the cloud formation, we hope
that our UCM can be of some use as a guide for future modelings of the
ultracool dwarfs as well as for interpretation of observed data of L and T
dwarfs.Comment: 43 pages, 13 figures, to appear in Astrophys. J. (May 20, 2004) Some
minor corrections including the address of our web site, which is now read
Single scalar top production with polarized beams in ep collisions at HERA
From the point of view of the R-parity breaking supersymmetric model, we
propose a scalar top (stop) search with longitudinally polarized electron (e-)
and positron(e+) beams which will soon be available at the upgraded HERA. Fully
polarized e- or e+ beams could produce the stop two times as much as
unpolarized beams, while they increase background events due to the process of
the standard model by about 30% in comparison with unpolarized ones. We show
that right-handed e+ beams at HERA is efficient to produce the stop in the
model. With 1 fb**(-1) of integrated luminosity we estimate reach in the
coupling constant lambda'(131) for masses of the stop in the range 160-400 GeV.
We can set a 95% confidence-level exclusion limit for lambda'(131) > 0.01-0.05
in the stop mass range of 240-280 GeV if no singal of the stop is observed. We
also point out that y(=Q**2/sx) distributions of e+ coming from the stop shows
the different behavior from those of the standard model.Comment: 12 pages, 6 eps figure
Spectral Classification and Effective Temperatures of L and T Dwarfs Based of Near-Infrared Spectra
We have obtained near-infrared spectra of L dwarfs, L/T transition objects
and T dwarfs using Subaru. Resulting spectra are examined in detail to see
their dependence on the spectral types. We have obtained bolometric
luminosities of the objects with known parallaxes in our sample, first by
integrating the spectra and second by K band bolometric correction. We derive
the relation between effective temperature and spectral type.Comment: To appear in May 20, 2004 issue of ApJ There is a companion paper by
Tsuji, Nakajima and Yanagisaw
Sensitivity of a Ground-Based Infrared Interferometer for Aperture Synthesis Imaging
Sensitivity limits of ground-based infrared interferometers using aperture
synthesis are presented. The motivation of this analysis is to compare an
interferometer composed of multiple large telescopes and a single giant
telescope with adaptive optics. In deriving these limits, perfect wavefront
correction by adaptive optics and perfect cophasing by fringe tracking are
assumed. We consider the case in which n beams are pairwise combined at
n(n-1)/2 detectors and the case in which all the n beams are combined at a
single detector. As a case study, we compare the point-source sensitivities of
interferometers composed of nine 10-m diameter telescopes and a 30-m diameter
single telescope with adaptive optics between 1 and 10 microns.Comment: 21 pages, 5 figures. Accepted for publication in PAS
Possible Excess in Charged Current Events with High-Q^2 at HERA from Stop and Sbottom Production
We investigate a production process e^+p \to \st X \to \sb W^+ X at HERA,
where we consider a decay mode \sb \to \bar{\nu}_e d of the sbottom in the
framework of an R-parity breaking supersymmetric standard model. Both processes
of the stop production e^+ d \to \st and the sbottom decay \sb \to
\bar{\nu}_e d are originated from an R-parity breaking superpotential
. One of signatures of the
process should be a large missing transverse momentum plus multijet events
corresponding to hadronic decays of the . It is shown that the signal could
appear as an event excess in the charged current (CC) processes with the high at HERA. We compare expected event distributions with
the CC data recently reported by the H1 and ZEUS groups at HERA. Methods for
extracting the signal from the standard CC processes are also discussed.Comment: 13 pages, LaTeX, 3 figure
Cytokeratin-negative small cell lung carcinoma
Cytokeratins (CK) are good markers of epithelial tumors, and most of carcinomas including small cell lung carcinoma (SCLC) expresses CK. Herein reported is a case of SCLC without CK expression
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