741 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
Improvement of Switching Speed of a 600-V Nonpunch-through Insulated Gate Bipolar Transistor Using Fast Neutron Irradiation
AbstractFast neutron irradiation was used to improve the switching speed of a 600-V nonpunch-through insulated gate bipolar transistor. Fast neutron irradiation was carried out at 30-MeV energy in doses of 1 × 108 n/cm2, 1 × 109 n/cm2, 1 × 1010 n/cm2, and 1 × 1011 n/cm2. Electrical characteristics such as current–voltage, forward on-state voltage drop, and switching speed of the device were analyzed and compared with those prior to irradiation. The on-state voltage drop of the initial devices prior to irradiation was 2.08 V, which increased to 2.10 V, 2.20 V, 2.3 V, and 2.4 V, respectively, depending on the irradiation dose. This effect arises because of the lattice defects generated by the fast neutrons. In particular, the turnoff delay time was reduced to 92 nanoseconds, 45% of that prior to irradiation, which means there is a substantial improvement in the switching speed of the device
DNA methylation loss promotes immune evasion of tumours with high mutation and copy number load
Mitotic cell division increases tumour mutation burden and copy number load, predictive markers of the clinical benefit of immunotherapy. Cell division correlates also with genomic demethylation involving methylation loss in late-replicating partial methylation domains. Here we find that immunomodulatory pathway genes are concentrated in these domains and transcriptionally repressed in demethylated tumours with CpG island promoter hypermethylation. Global methylation loss correlated with immune evasion signatures independently of mutation burden and aneuploidy. Methylome data of our cohort (n = 60) and a published cohort (n = 81) in lung cancer and a melanoma cohort (n = 40) consistently demonstrated that genomic methylation alterations counteract the contribution of high mutation burden and increase immunotherapeutic resistance. Higher predictive power was observed for methylation loss than mutation burden. We also found that genomic hypomethylation correlates with the immune escape signatures of aneuploid tumours. Hence, DNA methylation alterations implicate epigenetic modulation in precision immunotherapy
A new parametrization of the neutrino mixing matrix for neutrino oscillations
In this paper we study three active neutrino oscillations, favored by recent
data from SuperK and SNO, using a new parametrization of the lepton mixing
matrix constructed from a linear combination of the unit matrix , and a
hermitian unitary matrix , that is, .
There are only three real parameters in including the parameter .
It is interesting to find that experimental data on atmospheric neutrino
dictates the angle to be such that the and
mixing is maximal. The solar neutrino problem is solved via the MSW
effect with a small mixing angle, with depending on one small parameter
. The resulting mixing matrix with just two parameters ( and
) predicts that the oscillating probabilities for
and to be equal and of the order . The measurement of CP asymmetries at the proposed Neutrino
Factories would also provide a test of our parametrization.Comment: 10 pages, Retex, no figure
The Complementarity of Eastern and Western Hemisphere Long-Baseline Neutrino Oscillation Experiments
We present a general formalism for extracting information on the fundamental
parameters associated with neutrino masses and mixings from two or more long
baseline neutrino oscillation experiments. This formalism is then applied to
the current most likely experiments using neutrino beams from the Japan Hadron
Facility (JHF) and Fermilab's NuMI beamline. Different combinations of muon
neutrino or muon anti-neutrino running are considered. To extract the type of
neutrino mass hierarchy we make use of the matter effect. Contrary to naive
expectation, we find that both beams using neutrinos is more suitable for
determining the hierarchy provided that the neutrino energy divided by baseline
() for NuMI is smaller than or equal to that of JHF. Whereas to determine
the small mixing angle, , and the CP or T violating phase
, one neutrino and the other anti-neutrino is most suitable. We make
extensive use of bi-probability diagrams for both understanding and extracting
the physics involved in such comparisons.Comment: 21 pages, Latex, 3 postscript figure
Status of atmospheric neutrino(mu)<-->neutrino(tau) oscillations and decoherence after the first K2K spectral data
We review the status of nu_mu-->nu_tau flavor transitions of atmospheric
neutrinos in the 92 kton-year data sample collected in the first phase of the
Super-Kamiokande (SK) experiment, in combination with the recent spectral data
from the KEK-to-Kamioka (K2K) accelerator experiment (including 29 single-ring
muon events). We consider a theoretical framework which embeds flavor
oscillations plus hypothetical decoherence effects, and where both standard
oscillations and pure decoherence represent limiting cases. It is found that
standard oscillations provide the best description of the SK+K2K data, and that
the associated mass-mixing parameters are determined at 1 sigma (and d.o.f.=1)
as: Delta m^2=(2.6 +- 0.4)x10^{-3} eV^2 and sin^2(2theta)=1.00+0.00-0.05. As
compared with standard oscillations, the case of pure decoherence is
disfavored, although it cannot be ruled out yet. In the general case,
additional decoherence effects in the nu_mu-->nu_tau channel do not improve the
fit to the SK and K2K data, and upper bounds can be placed on the associated
decoherence parameter. Such indications, presently dominated by SK, could be
strengthened by further K2K data, provided that the current spectral features
are confirmed with higher statistics. A detailed description of the statistical
analysis of SK and K2K data is also given, using the so-called ``pull''
approach to systematic uncertainties.Comment: 18 pages (RevTeX) + 12 figures (PostScript
Probing the Planck Scale with Neutrino Oscillations
Quantum gravity "foam", among its various generic Lorentz non-invariant
effects, would cause neutrino mixing. It is shown here that, if the foam is
manifested as a nonrenormalizable effect at scale M, the oscillation length
generically decreases with energy as (E/M)^(-2). Neutrino observatories and
long-baseline experiments should have therefore already observed foam-induced
oscillations, even if M is as high as the Planck energy scale. The null
results, which can be further strengthened by better analysis of current data
and future experiments, can be taken as experimental evidence that Lorentz
invariance is fully preserved at the Planck scale, as is the case in critical
string theory.Comment: 11 pages, 2 figures. Final version published in PRD. 1 figure,
references, clarifications and explanations added. Results unchange
Time and Amplitude of Afterpulse Measured with a Large Size Photomultiplier Tube
We have studied the afterpulse of a hemispherical photomultiplier tube for an
upcoming reactor neutrino experiment. The timing, the amplitude, and the rate
of the afterpulse for a 10 inch photomultiplier tube were measured with a 400
MHz FADC up to 16 \ms time window after the initial signal generated by an LED
light pulse. The time and amplitude correlation of the afterpulse shows several
distinctive groups. We describe the dependencies of the afterpulse on the
applied high voltage and the amplitude of the main light pulse. The present
data could shed light upon the general mechanism of the afterpulse.Comment: 11 figure
Towards a unique formula for neutrino oscillations in vacuum
We show that all correct results obtained by applying quantum field theory to
neutrino oscillations can be understood in terms of a single oscillation
formula. In particular, the model proposed by Grimus and Stockinger is shown to
be a subcase of the model proposed by Giunti, Kim and Lee, while the new
oscillation formulas proposed by Ioannisian and Pilaftsis and by Shtanov are
disproved. We derive an oscillation formula without making any relativistic
assumption and taking into account the dispersion, so that the result is valid
for both neutrinos and mesons. This unification gives a stronger
phenomenological basis to the neutrino oscillation formula. We also prove that
the coherence length can be increased without bound by more accurate energy
measurements. Finally, we insist on the wave packet interpretation of the
quantum field treatments of oscillations.Comment: 30 pages, 1 figure; the proof that plane wave oscillations do no
exist is extended to stationary models; the influence of dispersion is
explained in more detail
The Cap in the Hat: Unoriented 2D Strings and Matrix(-Vector) Models
We classify the possible bosonic and Type 0 unoriented string theories in two
dimensions, and find their dual matrix(-vector) models. There are no RP^2 R-R
tadpoles in any of the models, but many of them possess a massless tachyon
tadpole. Thus all the models we find are consistent two-dimensional string
vacua, but some get quantum corrections to their classical tachyon background.
Where possible, we solve the tadpole cancellation condition, and find all the
tachyon tadpole-free theories.Comment: 34 pages, LaTeX; Errors corrected in some of the open string
representations in tables 1, 2 and 3. References and acknowledgments adde
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