739 research outputs found
Efficient chaining of seeds in ordered trees
We consider here the problem of chaining seeds in ordered trees. Seeds are
mappings between two trees Q and T and a chain is a subset of non overlapping
seeds that is consistent with respect to postfix order and ancestrality. This
problem is a natural extension of a similar problem for sequences, and has
applications in computational biology, such as mining a database of RNA
secondary structures. For the chaining problem with a set of m constant size
seeds, we describe an algorithm with complexity O(m2 log(m)) in time and O(m2)
in space
Quasi Two-dimensional Transfer of Elastic Waves
A theory for multiple scattering of elastic waves is presented in a random
medium bounded by two ideal free surfaces, whose horizontal size is infinite
and whose transverse size is smaller than the mean free path of the waves. This
geometry is relevant for seismic wave propagation in the Earth crust. We derive
a time-dependent, quasi-2D radiative transfer equation, that describes the
coupling of the eigenmodes of the layer (surface Rayleigh waves, SH waves, and
Lamb waves). Expressions are found that relate the small-scale fluctuations to
the life time of the modes and to their coupling rates. We discuss a diffusion
approximation that simplifies the mathematics of this model significantly, and
which should apply at large lapse times. Finally, coherent backscattering is
studied within the quasi-2D radiative transfer equation for different source
and detection configurations.Comment: REVTeX, 36 pages with 10 figures. Submitted to Phys. Rev.
Sarcopenia/Muscle Mass is not a Prognostic Factor for Short- and Long-Term Outcome After Esophagectomy for Cancer
Background: Recent studies have suggested that sarcopenia is a prognostic risk indicator of postoperative complications and predicts survival in cancer patients. The aim of this study is to investigate whether sarcopenia is associated with postoperative short-term outcome (morbidity and mortality) and long-term survival in patients undergoing esophagectomy for cancer after neoadjuvant chemoradiotherapy. Methods: All patients who underwent neoadjuvant chemoradiotherapy followed by esophagectomy for cancer, and of whom an adequate CT scan was available, were included in the current study. The presence of sarcopenia was defined by CT imaging using cut-off values of the total cross-sectional muscle tissue measured transversely at the third lumbar level. Results: A total number of 120 patients were eligible for analysis. Almost half of the patients (N = 54, 45 %) were classified as having sarcopenia; 24 sarcopenic patients (44 %) had overweight and 5 sarcopenic patients (9 %) were obese. Overall morbidity and mortality rate did not differ significantly between sarcopenic and non-sarcopenic patients, nor did long-term overall or disease-free survival. Also sarcopenic obesity was not associated with worse outcome. Conclusion: The presence of sarcopenia was not associated with a negative short- and long-term outcome in this selected group of esophageal cancer patients after neoadjuvant chemoradiotherapy followed by esophagectomy
Simultaneous solution of Kompaneets equation and Radiative Transfer equation in the photon energy range 1 - 125 KeV
Radiative transfer equation in plane parallel geometry and Kompaneets
equation is solved simultaneously to obtain theoretical spectrum of 1-125 KeV
photon energy range. Diffuse radiation field is calculated using
time-independent radiative transfer equation in plane parallel geometry, which
is developed using discrete space theory (DST) of radiative transfer in a
homogeneous medium for different optical depths. We assumed free-free emission
and absorption and emission due to electron gas to be operating in the medium.
The three terms and where is photon phase density and , in Kompaneets equation and those due to
free-free emission are utilized to calculate the change in the photon phase
density in a hot electron gas. Two types of incident radiation are considered:
(1) isotropic radiation with the modified black body radiation [1] and
(2) anisotropic radiation which is angle dependent. The emergent radiation at
and reflected radiation are calculated by using the
diffuse radiation from the medium. The emergent and reflected radiation contain
the free-free emission and emission from the hot electron gas. Kompaneets
equation gives the changes in photon phase densities in different types of
media. Although the initial spectrum is angle dependent, the Kompaneets
equation gives a spectrum which is angle independent after several Compton
scattering times.Comment: 31 pages, 8 figures, Accepte
In vivo and in vitro synthesis of CM-proteins (A-hordeins) from barley (Hordeum vulgare L.)
CM-proteins from barley endosperm (CMa, CMb, CMc, CMd), which are the main components of the A-hordein fraction, are synthesized most actively 10 to 30 d after anthesis (maximum at 15–20 d). They are synthesized by membranebound polysomes as precursors of higher apparent molecular weight (13,000–21,000) than the mature proteins (12,000–16,000). The largest in vitro product (21,000) is the putative precursor of protein CMd (16,000), as it is selected with anti-CMd monospecific IgG's, and is coded by an mRNA of greater sedimentation coefficient (9 S) than those encoding the other three proteins (7.5 S). CM-proteins always appear in the soluble fraction, following different homogenization and subcellular fractionation procedures, indicating that these proteins are transferred to the soluble fraction after processing
Large Deviations for Random Trees
We consider large random trees under Gibbs distributions and prove a Large
Deviation Principle (LDP) for the distribution of degrees of vertices of the
tree. The LDP rate function is given explicitly. An immediate consequence is a
Law of Large Numbers for the distribution of vertex degrees in a large random
tree. Our motivation for this study comes from the analysis of RNA secondary
structures.Comment: 10 page
Gravitation and inertia; a rearrangement of vacuum in gravity
We address the gravitation and inertia in the framework of 'general gauge
principle', which accounts for 'gravitation gauge group' generated by hidden
local internal symmetry implemented on the flat space. We connect this group to
nonlinear realization of the Lie group of 'distortion' of local internal
properties of six-dimensional flat space, which is assumed as a toy model
underlying four-dimensional Minkowski space. The agreement between proposed
gravitational theory and available observational verifications is satisfactory.
We construct relativistic field theory of inertia and derive the relativistic
law of inertia. This theory furnishes justification for introduction of the
Principle of Equivalence. We address the rearrangement of vacuum state in
gravity resulting from these ideas.Comment: 17 pages, no figures, revtex4, Accepted for publication in Astrophys.
Space Sc
Running coupling: Does the coupling between dark energy and dark matter change sign during the cosmological evolution?
In this paper we put forward a running coupling scenario for describing the
interaction between dark energy and dark matter. The dark sector interaction in
our scenario is free of the assumption that the interaction term is
proportional to the Hubble expansion rate and the energy densities of dark
sectors. We only use a time-variable coupling (with the scale factor
of the universe) to characterize the interaction . We propose a
parametrization form for the running coupling in which the
early-time coupling is given by a constant , while today the coupling is
given by another constant, . For investigating the feature of the running
coupling, we employ three dark energy models, namely, the cosmological constant
model (), the constant model (), and the time-dependent
model (). We constrain the models with the current
observational data, including the type Ia supernova, the baryon acoustic
oscillation, the cosmic microwave background, the Hubble expansion rate, and
the X-ray gas mass fraction data. The fitting results indicate that a
time-varying vacuum scenario is favored, in which the coupling crosses
the noninteracting line () during the cosmological evolution and the sign
changes from negative to positive. The crossing of the noninteracting line
happens at around , and the crossing behavior is favored at about
1 confidence level. Our work implies that we should pay more attention
to the time-varying vacuum model and seriously consider the phenomenological
construction of a sign-changeable or oscillatory interaction between dark
sectors.Comment: 8 pages, 5 figures; refs added; to appear in EPJ
Gravitational Geometric Phase in the Presence of Torsion
We investigate the relativistic and non-relativistic quantum dynamics of a
neutral spin-1/2 particle submitted an external electromagnetic field in the
presence of a cosmic dislocation. We analyze the explicit contribution of the
torsion in the geometric phase acquired in the dynamic of this neutral
spinorial particle. We discuss the influence of the torsion in the relativistic
geometric phase. Using the Foldy-Wouthuysen approximation, the non-relativistic
quantum dynamics are studied and the influence of the torsion in the
Aharonov-Casher and He-McKellar-Wilkens effects are discussed.Comment: 14 pages, no figur
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