15,358 research outputs found
Supersymmetric heterotic string backgrounds
We present the main features of the solution of the gravitino and dilatino
Killing spinor equations derived in hep-th/0510176 and hep-th/0703143 which
have led to the classification of geometric types of all type I backgrounds. We
then apply these results to the supersymmetric backgrounds of the heterotic
string. In particular, we solve the gaugino Killing spinor equation together
with the other two Killing spinor equations of the theory. We also use our
results to classify all supersymmetry conditions of ten-dimensional gauge
theory.Comment: 12 pages, v2: gauge theory applications are stressed and references
adde
Effects of coarse-graining on the scaling behavior of long-range correlated and anti-correlated signals
We investigate how various coarse-graining methods affect the scaling
properties of long-range power-law correlated and anti-correlated signals,
quantified by the detrended fluctuation analysis. Specifically, for
coarse-graining in the magnitude of a signal, we consider (i) the Floor, (ii)
the Symmetry and (iii) the Centro-Symmetry coarse-graining methods. We find,
that for anti-correlated signals coarse-graining in the magnitude leads to a
crossover to random behavior at large scales, and that with increasing the
width of the coarse-graining partition interval this crossover moves
to intermediate and small scales. In contrast, the scaling of positively
correlated signals is less affected by the coarse-graining, with no observable
changes when a crossover appears at small
scales and moves to intermediate and large scales with increasing . For
very rough coarse-graining () based on the Floor and Symmetry
methods, the position of the crossover stabilizes, in contrast to the
Centro-Symmetry method where the crossover continuously moves across scales and
leads to a random behavior at all scales, thus indicating a much stronger
effect of the Centro-Symmetry compared to the Floor and the Symmetry methods.
For coarse-graining in time, where data points are averaged in non-overlapping
time windows, we find that the scaling for both anti-correlated and positively
correlated signals is practically preserved. The results of our simulations are
useful for the correct interpretation of the correlation and scaling properties
of symbolic sequences.Comment: 19 pages, 13 figure
The N\'eel order for a frustrated antiferromagnetic Heisenberg model: beyond linear spin-wave theory
Within Dyson-Maleev (DM) transformation and self-consistent mean-field
treatment, the N\'eel order/disorder transition is studied for an
antiferromagnetic Heisenberg model which is defined on a square lattice with a
nearest neighbour exchange and a next-nearest neighbour exchange
along only one of the diagonals. It is found that the N\'eel order may exist up
to , beyond its classically stable regime. This result
qualitatively improves that from linear spin-wave theory based on
Holstein-Primakoff transformation.Comment: 10 pages, 4 eps figure
Self-Similar Blowup Solutions to the 2-Component Degasperis-Procesi Shallow Water System
In this article, we study the self-similar solutions of the 2-component
Degasperis-Procesi water system:% [c]{c}%
\rho_{t}+k_{2}u\rho_{x}+(k_{1}+k_{2})\rho u_{x}=0
u_{t}-u_{xxt}+4uu_{x}-3u_{x}u_{xx}-uu_{xxx}+k_{3}\rho\rho_{x}=0. By the
separation method, we can obtain a class of self-similar solutions,% [c]{c}%
\rho(t,x)=\max(\frac{f(\eta)}{a(4t)^{(k_{1}+k_{2})/4}},\text{}0),\text{}u(t,x)=\frac{\overset{\cdot}{a}(4t)}{a(4t)}x
\overset{\cdot\cdot}{a}(s)-\frac{\xi}{4a(s)^{\kappa}}=0,\text{}a(0)=a_{0}%
\neq0,\text{}\overset{\cdot}{a}(0)=a_{1}
f(\eta)=\frac{k_{3}}{\xi}\sqrt{-\frac{\xi}{k_{3}}\eta^{2}+(\frac{\xi}{k_{3}}\alpha)
^{2}}% where with , and are constants. which the
local or global behavior can be determined by the corresponding Emden equation.
The results are very similar to the one obtained for the 2-component
Camassa-Holm equations. Our analytical solutions could provide concrete
examples for testing the validation and stabilities of numerical methods for
the systems. With the characteristic line method, blowup phenomenon for
is also studied.Comment: 13 Pages, Key Words: 2-Component Degasperis-Procesi, Shallow Water
System, Analytical Solutions, Blowup, Global, Self-Similar, Separation
Method, Construction of Solutions, Moving Boundary, 2-Component Camassa-Holm
Equation
Self-assembly of magnetic iron oxide nanoparticles into cuboidal superstructures
This chapter describes the synthesis and some characteristics of magnetic
iron oxide nanoparticles, mainly nanocubes, and focus on their self-assembly
into crystalline cuboids in dispersion. The influence of external magnetic
fields, the concentration of particles, and the temperature on the assembly
process is experimentally investigated
Discrete Spectrum of the Graviton in the Black Hole Background
The discrete spectrum of fluctuations of the metric about an black
hole background are found. These modes are the strong coupling limit of so
called glueball states in a dual 3-d Yang-Mills theory with quantum numbers
. For the ground state modes, we find the mass
relation: . Contrary to expectation, the
mass of our new state () associated with the graviton is
smaller than the mass of the state () from the dilaton. In
fact the dilatonic excitations are exactly degenerate with our tensor
states. We find that variational methods gives remarkably accurate mass
estimates for all three low-lying levels while a WKB treatment describes the
higher modes well.Comment: harvmac, 30 pages, i eps-fil
Inverse Scattering Transform for the Camassa-Holm equation
An Inverse Scattering Method is developed for the Camassa-Holm equation. As
an illustration of our approach the solutions corresponding to the
reflectionless potentials are explicitly constructed in terms of the scattering
data. The main difference with respect to the standard Inverse Scattering
Transform lies in the fact that we have a weighted spectral problem. We
therefore have to develop different asymptotic expansions.Comment: 17 pages, LaTe
Pathway analysis and transcriptomics improve protein identification by shotgun proteomics from samples comprising small number of cells - a benchmarking study
BACKGROUND: Proteomics research is enabled with the high-throughput technologies, but our ability to identify expressed proteome is limited in small samples. The coverage and consistency of proteome expression are critical problems in proteomics. Here, we propose pathway analysis and combination of microproteomics and transcriptomics analyses to improve mass-spectrometry protein identification from small size samples.
RESULTS: Multiple proteomics runs using MCF-7 cell line detected 4,957 expressed proteins. About 80% of expressed proteins were present in MCF-7 transcripts data; highly expressed transcripts are more likely to have expressed proteins. Approximately 1,000 proteins were detected in each run of the small sample proteomics. These proteins were mapped to gene symbols and compared with gene sets representing canonical pathways, more than 4,000 genes were extracted from the enriched gene sets. The identified canonical pathways were largely overlapping between individual runs. Of identified pathways 182 were shared between three individual small sample runs.
CONCLUSIONS: Current technologies enable us to directly detect 10% of expressed proteomes from small sample comprising as few as 50 cells. We used knowledge-based approaches to elucidate the missing proteome that can be verified by targeted proteomics. This knowledge-based approach includes pathway analysis and combination of gene expression and protein expression data for target prioritization. Genes present in both the enriched gene sets (canonical pathways collection) and in small sample proteomics data correspond to approximately 50% of expressed proteomes in larger sample proteomics data. In addition, 90% of targets from canonical pathways were estimated to be expressed. The comparison of proteomics and transcriptomics data, suggests that highly expressed transcripts have high probability of protein expression. However, approximately 10% of expressed proteins could not be matched with the expressed transcripts.The cost of this publication was funded by Vladimir Brusic. (Vladimir Brusic)Published versio
Ginzburg-Landau Theory of Josephson Field Effect Transistors
A theoretical model of high-T_c Josephson Field Effect Transistors (JoFETs)
based on a Ginzburg-Landau free energy expression whose parameters are field-
and spatially- dependent is developed. This model is used to explain
experimental data on JoFETs made by the hole-overdoped Ca-SBCO bicrystal
junctions (three terminal devices). The measurements showed a large modulation
of the critical current as a function of the applied voltage due to charge
modulation in the bicrystal junction. The experimental data agree with the
solutions of the theoretical model. This provides an explanation of the large
field effect, based on the strong suppresion of the carrier density near the
grain boundary junction in the absence of applied field and the subsequent
modulation of the density by the field.Comment: REVTEX, 4 figures upon request, submitted to Appl. Phys. Let
- …