6,489 research outputs found
The superficial brachial artery : a case report
A superficial brachial artery is an anomalous branch of the brachial artery that runs superficial to the median nerve; it is usually associated with a deep brachial branch that runs deep to this nerve. A case is described of a superficial brachial artery. It is of the type where the artery terminates in the cubital fossa by division into radial and ulnar arteries. It is associated with a superficial ulnar artery, and a deep brachial artery that is continued into the forearm as the common interosseous artery, a rare occurrence. The clinical importance and the dangers of this vascular anomaly are discussed. In reparative surgery, an accurate knowledge of the relationship, course and particularly the possible variations of the brachial artery is of considerable importance.peer-reviewe
Black hole perturbation in nondynamical and dynamical Chern-Simons gravity
Chern-Simons gravitational theories are extensions of general relativity in
which the parity is violated due to the Chern-Simons term. We study linear
perturbations on the static and spherically symmetric background spacetime both
for nondynamical and dynamical Chern-Simons theories. We do not make an
assumption that the background Chern-Simons scalar field vanishes, which has
been adopted in the literature. By eliminating nondynamical variables using
their constraint equations, we derive the reduced second order action from
which a set of closed evolution equations containing only dynamical variables
are immediately obtained and therefore the number of propagating degrees of
freedom as well. It is found that ghost is present both for the nondynamical
case and for the dynamical case unless the background Chern-Simons scalar field
vanishes. It is also found that if the background scalar field vanishes, ghost
degrees of freedom are killed and all the modes propagate at the speed of
light.Comment: 18 pages; matches the published version in Phys. Rev.
Alien Registration- Raque, Felice L. (Portland, Cumberland County)
https://digitalmaine.com/alien_docs/25462/thumbnail.jp
A TDDFT study of the excited states of DNA bases and their assemblies
We present a detailed study of the optical absorption spectra of DNA bases
and base pairs, carried out by means of time dependent density functional
theory. The spectra for the isolated bases are compared to available
theoretical and experimental data and used to assess the accuracy of the method
and the quality of the exchange-correlation functional: Our approach turns out
to be a reliable tool to describe the response of the nucleobases. Furthermore,
we analyze in detail the impact of hydrogen bonding and -stacking in the
calculated spectra for both Watson-Crick base pairs and Watson-Crick stacked
assemblies. We show that the reduction of the UV absorption intensity
(hypochromicity) for light polarized along the base-pair plane depends strongly
on the type of interaction. For light polarized perpendicular to the basal
plane, the hypochromicity effect is reduced, but another characteristic is
found, namely a blue shift of the optical spectrum of the base-assembly
compared to that of the isolated bases. The use of optical tools as
fingerprints for the characterization of the structure (and type of
interaction) is extensively discussed.Comment: 31 pages, 8 figure
Excess of weight: is it a modifiable predictive and prognostic factor in locally advanced rectal cancer?
To evaluate the relationship between body mass index (BMI) and rates of treatment tolerance and clinical outcomes in patients with locally advanced rectal cancer treated with a multimodality approach.
PATIENTS AND METHODS:
This study was conducted on 56 patients with histologically proven rectal adenocarcinoma, staged T3-4, and/or node-positive tumor, which underwent intensified radiochemotherapy (RT-CHT) treatment before surgery. We calculated adiposity indices and analyzed their influence on treatment tolerance and clinical outcomes.
RESULTS:
Distribution of the 56 patients according to BMI was BMI < 25 kg/m2 (n = 19; 33.9%), BMI 25-29 kg/m2 (n = 29; 51.8%) and BMI ≥ 30 kg/m2 (n = 8; 14.3%). BMI had no significant influence on neo-adjuvant treatment-related toxicity. With a median follow-up of 23 months (range 11-47), the 2-year survival was 85.7%. We did not observe any significant difference among the three BMI categories for any of the outcomes.
CONCLUSIONS:
This study suggested no evident links between overweight and survival in patients with locally advanced rectal carcinoma treated with neo-adjuvant RT-CHT. Overweight patients tolerate treatment as normal-weight patients
Dark matter from dark energy-baryonic matter couplings
We present a scenario in which a scalar field dark energy is coupled to the
trace of the energy momentum tensor of the baryonic matter fields. In the
slow-roll regime, this interaction could give rise to the cosmological features
of dark matter. We work out the cosmological background solutions and fit the
parameters of the model using the Union 2 supernovae data set. Then, we develop
the cosmological perturbations up to linear order, and we find that the
perturbed variables have an acceptable behavior, in particular the density
contrast of baryonic matter grows similar to that in the CDM model for
a suitable choice of the strength parameter of the coupling.Comment: 10 pages, 8 figures, in this version small typos are corrected and it
matches the published version in Phys. Rev. D15, January 201
On the gravitomagnetic effects in cylindrically symmetric spacetimes
Using gyroscopes we generalize results, obtained for the gravitomagnetic
clock effect in the particular case when the exterior spacetime is produced by
a rotating dust cylinder, to the case when the vacuum spacetime is described by
the general cylindrically symmetric Lewis spacetime. Results are contrasted
with those obtained for the Kerr spacetime.Comment: 11 pages Latex, to appear in J.Math.Phy
Line Integral Methods for Conservative Problems
Line Integral Methods for Conservative Problems explains the numerical solution of differential equations within the framework of geometric integration, a branch of numerical analysis that devises numerical methods able to reproduce (in the discrete solution) relevant geometric properties of the continuous vector field. The book focuses on a large set of differential systems named conservative problems, particularly Hamiltonian systems.
Assuming only basic knowledge of numerical quadrature and Runge–Kutta methods, this self-contained book begins with an introduction to the line integral methods. It describes numerous Hamiltonian problems encountered in a variety of applications and presents theoretical results concerning the main instance of line integral methods: the energy-conserving Runge–Kutta methods, also known as Hamiltonian boundary value methods (HBVMs). The authors go on to address the implementation of HBVMs in order to recover in the numerical solution what was expected from the theory. The book also covers the application of HBVMs to handle the numerical solution of Hamiltonian partial differential equations (PDEs) and explores extensions of the energy-conserving methods.
With many examples of applications, this book provides an accessible guide to the subject yet gives you enough details to allow concrete use of the methods. MATLAB codes for implementing the methods are available online
Line Integral Methods for Conservative Problems
Line Integral Methods for Conservative Problems explains the numerical solution of differential equations within the framework of geometric integration, a branch of numerical analysis that devises numerical methods able to reproduce (in the discrete solution) relevant geometric properties of the continuous vector field. The book focuses on a large set of differential systems named conservative problems, particularly Hamiltonian systems.
Assuming only basic knowledge of numerical quadrature and Runge–Kutta methods, this self-contained book begins with an introduction to the line integral methods. It describes numerous Hamiltonian problems encountered in a variety of applications and presents theoretical results concerning the main instance of line integral methods: the energy-conserving Runge–Kutta methods, also known as Hamiltonian boundary value methods (HBVMs). The authors go on to address the implementation of HBVMs in order to recover in the numerical solution what was expected from the theory. The book also covers the application of HBVMs to handle the numerical solution of Hamiltonian partial differential equations (PDEs) and explores extensions of the energy-conserving methods.
With many examples of applications, this book provides an accessible guide to the subject yet gives you enough details to allow concrete use of the methods. MATLAB codes for implementing the methods are available online
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