550 research outputs found
Community analysis of aggregated bacteria in southern Lake Baikal
The main aim of this study is to unveiling the community structure of aggregated bacteria in lake Baikal and determining the relations with free-living bacteria. For achieving this aim, FISH method was applied to free-living and aggregated bacteria in Lake Baikal at April, 2001. Bacterial counts of free-living bacteria by DAPI staining ranged from 0.2×10⁶ to 3.2×10⁶ cells·ml⁻¹, which decreased with depths, whereas aggregated bacterial numbers dramatically increased with depths, ranged from 0.4×10⁴ to 3.3×10⁴ cells·ml⁻¹. Also, the ratios of EUB probe binding cells to DAPI counts ranged from 52.3 to 74.1% in free-living bacteria, from 39.6 to 66.7% in aggregated bacteria, respectively. Community composition of aggregated bacteria was very different from free-livng bacteria. Especially, that is remarked at 25m depth which is observed the highest value phytoplankton. The vertical profile of aggregated bacteria community was very particular. β-Proteobacteria was increasing with depth till 100m. In 250m depth, γ-Proteobacteria was 44% of DAPI bound cells, while other groups were less than 1%. In conclusion, the bacterial community structures of free-living and aggregated bacteria were very different, and they sustain the independent ecosystem separately.Article信州大学山地水環境教育研究センター研究報告 2: 91-95(2004)departmental bulletin pape
Extravariables in the BRST Quantization of Second-Class Constrained Systems; Existence Theorems
In this paper we show how the BRST quantization can be applied to systems
possessing only second-class constraints through their conversion to some
first-class ones starting with our method exposed in [Nucl.Phys. B456
(1995)473]. Thus, it is proved that i) for a certain class of second-class
systems there exists a standard coupling between the variables of the original
phase-space and some extravariables such that we can transform the original
system into a one-parameter family of first-class systems; ii) the BRST
quantization of this family in a standard gauge leads to the same path integral
as that of the original system. The analysis is accomplished in both reducible
and irreducible cases. In the same time, there is obtained the Lagrangian
action of the first-class family and its provenience is clarified. In this
context, the Wess-Zumino action is also derived. The results from the
theoretical part of the paper are exemplified in detail for the massive
Yang-Mills theory and for the massive abelian three-form gauge fields.Comment: LaTeX, 37 pages; Correctly formatted version; The authors may be
reached at e-mail address: [email protected]
EUS-Guided Biliary Drainage
The echoendoscopic biliary drainage is an option to treat obstructive jaundices when ERCP drainage fails. These procedures compose alternative methods to the side of surgery and percutaneous transhepatic biliary drainage, and it was only possible by the continuous development and improvement of echoendoscopes and accessories. The development of linear setorial array echoendoscopes in early 1990 brought a new approach to diagnostic and therapeutic dimenion on echoendoscopy capabilities, opening the possibility to perform punction over direct ultrasonographic view. Despite of the high success rate and low morbidity of biliary drainage obtained by ERCP, difficulty could be found at the presence of stent tumor ingrown, tumor gut compression, periampulary diverticula, and anatomic variation. The echoendoscopic technique starts performing punction and contrast of the left biliary tree. When performed from gastric wall, the access is made through hepatic segment III. From duodenum, direct common bile duct punction. Dilatation is required before stent introduction, and a plastic or metallic stent is introduced. This phrase should be replaced by: diathermic dilatation of the puncturing tract is required using a 6F cystostome. The technical success of hepaticogastrostomy is near 98%, and complications are present in 36%: pneumoperitoneum, choleperitoneum, infection, and stent disfunction. To prevent bile leakage, we have used the 2 stent techniques, the first stent introduced was a long uncovered metallic stent (8 or 10 cm), and inside this first stent a second fully covered stent of 6 cm was delivered to bridge the bile duct and the stomach. Choledochoduodenostomy overall success rate is 92% and described complications include, in frequency order, pneumoperitoneum and focal bile peritonitis, present in 19%. By the last 10 years, the technique was especially performed in reference centers, by ERCP experienced groups, and this seems to be a general guideline to safer procedure execution
Aspects of Magnetic Field Configurations in Planar Nonlinear Electrodynamics
In the framework of three-dimensional Born-Infeld Electrodynamics, we pursue
an investigation of the consequences of the space-time dimensionality on the
existence of magnetostatic fields generated by electric charges at rest in an
inertial frame, which are present in its four-dimensional version. Our analysis
reveals interesting features of the model. In fact, a magnetostatic field
associated with an electric charge at rest does not appear in this case.
Interestingly, the addition of the topological term (Chern-Simons) to
Born-Infeld Electrodynamics yields the appearance of the magnetostatic field.
We also contemplate the fields associated to the would-be-magnetic monopole in
three dimensions.Comment: 8 page
Enhanced electrical and optical properties of room temperature deposited Aluminium doped Zinc Oxide (AZO) thin films by excimer laser annealing
High quality transparent conductive oxides (TCOs) often require a high thermal budget fabrication process. In this study, Excimer Laser Annealing (ELA) at a wavelength of 248 nm has been explored as a processing mechanism to facilitate low thermal budget fabrication of high quality aluminium doped zinc oxide (AZO) thin films. 180 nm thick AZO films were prepared by radio frequency magnetron sputtering at room temperature on fused silica substrates. The effects of the applied RF power and the sputtering pressure on the outcome of ELA at different laser energy densities and number of pulses have been investigated. AZO films deposited with no intentional heating at 180 W, and at 2 mTorr of 0.2% oxygen in argon were selected as the optimum as-deposited films in this work, with a resistivity of 1×10−3 Ω.cm, and an average visible transmission of 85%. ELA was found to result in noticeably reduced resistivity of 5×10−4 Ω.cm, and enhancing the average visible transmission to 90% when AZO is processed with 5 pulses at 125 mJ/cm2. Therefore, the combination of RF magnetron sputtering and ELA, both low thermal budget and scalable techniques, can provide a viable fabrication route of high quality AZO films for use as transparent electrodes
The glassy response of solid He-4 to torsional oscillations
We calculated the glassy response of solid He-4 to torsional oscillations
assuming a phenomenological glass model. Making only a few assumptions about
the distribution of glassy relaxation times in a small subsystem of otherwise
rigid solid He-4, we can account for the magnitude of the observed period shift
and concomitant dissipation peak in several torsion oscillator experiments. The
implications of the glass model for solid He-4 are threefold: (1) The dynamics
of solid He-4 is governed by glassy relaxation processes. (2) The distribution
of relaxation times varies significantly between different torsion oscillator
experiments. (3) The mechanical response of a torsion oscillator does not
require a supersolid component to account for the observed anomaly at low
temperatures, though we cannot rule out its existence.Comment: 9 pages, 4 figures, presented at QFS200
Brane cosmology with curvature corrections
We study the cosmology of the Randall-Sundrum brane-world where the
Einstein-Hilbert action is modified by curvature correction terms: a
four-dimensional scalar curvature from induced gravity on the brane, and a
five-dimensional Gauss-Bonnet curvature term. The combined effect of these
curvature corrections to the action removes the infinite-density big bang
singularity, although the curvature can still diverge for some parameter
values. A radiation brane undergoes accelerated expansion near the minimal
scale factor, for a range of parameters. This acceleration is driven by the
geometric effects, without an inflaton field or negative pressures. At late
times, conventional cosmology is recovered.Comment: RevTex4, 8 pages, no figures, minor change
Magnetic phases and reorientation transitions in antiferromagnetically coupled multilayers
In antiferromagnetically coupled superlattices grown on (001) faces of cubic
substrates, e.g. based on materials combinations as Co/Cu, Fe/Si, Co/Cr, or
Fe/Cr, the magnetic states evolve under competing influence of bilinear and
biquadratic exchange interactions, surface-enhanced four-fold in-plane
anisotropy, and specific finite-size effects. Using phenomenological
(micromagnetic) theory, a comprehensive survey of the magnetic states and
reorientation transitions has been carried out for multilayer systems with even
number of ferromagnetic sub-layers and magnetizations in the plane. In
two-layer systems (N=2) the phase diagrams in dependence on components of the
applied field in the plane include ``swallow-tail'' type regions of
(metastable) multistate co-existence and a number of continuous and
discontinuous reorientation transitions induced by radial and transversal
components of the applied field. In multilayers (N \ge 4) noncollinear states
are spatially inhomogeneous with magnetization varying across the multilayer
stack. For weak four-fold anisotropy the magnetic states under influence of an
applied field evolve by a complex continuous reorientation into the saturated
state. At higher anisotropy they transform into various inhomogeneous and
asymmetric structures. The discontinuous transitions between the magnetic
states in these two-layers and multilayers are characterized by broad ranges of
multi-phase coexistence of the (metastable) states and give rise to specific
transitional domain structures.Comment: Manuscript 34 pages, 14 figures; submitted for publicatio
Characterization of host tolerance to Striga hermonthica
One of the most promising control options against the parasitic weed Striga hermonthica is the use of crop varieties that combine resistance with high levels of tolerance. The aim of this study was to clarify the relation between Striga infestation level, Striga infection level and relative yield loss of sorghum and to use this insight for exploring the options for a proper screening procedure for tolerance. In three pot experiments, conducted in Mali (2003) and The Netherlands (2003, 2004), four sorghum genotypes were exposed to a range of Striga infestation levels, ranging from 0.0625 to 16 seeds cm−3. Observations included regular Striga emergence counts and sorghum grain yield at maturity.
There were significant genotype, infestation and genotype × infestation effects on sorghum yield. The relation between infestation level and infection level was density dependent. Furthermore, the relation between Striga infection level and relative yield loss was non-linear, though for the most resistant genotype Framida only the linear part of the relation was obtained, as even at high infestation levels only moderate infection levels were achieved. The results suggest that for resistant genotypes, tolerance can best be quantified as a reduced relative yield loss per aboveground Striga plant, whereas for less resistant genotypes the maximum relative yield loss can best be used. Whether both expressions of tolerance are interrelated could not be resolved. Complications of screening for tolerance under field conditions are discussed
Slowly rotating charged black holes in anti-de Sitter third order Lovelock gravity
In this paper, we study slowly rotating black hole solutions in Lovelock
gravity (n=3). These exact slowly rotating black hole solutions are obtained in
uncharged and charged cases, respectively. Up to the linear order of the
rotating parameter a, the mass, Hawking temperature and entropy of the
uncharged black holes get no corrections from rotation. In charged case, we
compute magnetic dipole moment and gyromagnetic ratio of the black holes. It is
shown that the gyromagnetic ratio keeps invariant after introducing the
Gauss-Bonnet and third order Lovelock interactions.Comment: 14 pages, no figur
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