546 research outputs found
Stationary Rotating Strings as Relativistic Particle Mechanics
Stationary rotating strings can be viewed as geodesic motions in appropriate
metrics on a two-dimensional space. We obtain all solutions describing
stationary rotating strings in flat spacetime as an application. These rotating
strings have infinite length with various wiggly shapes. Averaged value of the
string energy, the angular momentum and the linear momentum along the string
are discussed.Comment: 20pages, 7 figure
An anatomic study of the accessory anterolateral talar facet
Background: A small accessory facet with articular surface morphology is occasionally seen on the talus, bordering on the lateral end of the sinus tarsi. This facet has been named the accessory anterolateral talar facet. However, few anatomical studies have addressed this facet. Here we present the precise morphology of accessory anterolateral talar facet with emphasis on anatomical correlation between the presence of this facet and the angle of the infero-lateral surface of the talus (talar infero-lateral surface — TILS angle). Materials and methods: A total of 22 (11 male, 11 female) adult cadavers with no known pathological conditions in the talocalcaneal joints were examined during educational dissection at Nagoya City University Medical School in 2013. After exclusion of 1 joint due to the poor condition of the talus, 43 talus (22 right, 21 left) were analysed. We judged the presence of the accessory anterolateral talar facet and measured TILS angle. We performed statistical analysis on the point of laterality, gender difference and the difference in the TILS angles in tali with or without the accessory anterolateral talar facets. Results: An accessory anterolateral talar facet was identified in 11 (26%) of the 43 specimens. Of the 21 cadavers with paired talar specimens, 5 displayed the facet bilaterally. Conclusions: There was no sex difference and no significant laterality, however we found that TILS angle was significantly larger in accessory anterolateral talar facet positive samples than in negative ones
Exactly solvable strings in Minkowski spacetime
We study the integrability of the equations of motion for the Nambu-Goto
strings with a cohomogeneity-one symmetry in Minkowski spacetime. A
cohomogeneity-one string has a world surface which is tangent to a Killing
vector field. By virtue of the Killing vector, the equations of motion can be
reduced to the geodesic equation in the orbit space. Cohomogeneity-one strings
are classified into seven classes (Types I to VII). We investigate the
integrability of the geodesic equations for all the classes and find that the
geodesic equations are integrable. For Types I to VI, the integrability comes
from the existence of Killing vectors on the orbit space which are the
projections of Killing vectors on Minkowski spacetime. For Type VII, the
integrability is related to a projected Killing vector and a nontrivial Killing
tensor on the orbit space. We also find that the geodesic equations of all
types are exactly solvable, and show the solutions.Comment: 11 pages, a reference added, some points clarifie
Lensing Effects on Gravitational Waves in a Clumpy Universe -Effects of Inhomogeneity on the Distance-Redshift Relation-
The distance-redshift relation determined by means of gravitational waves in
the clumpy universe is simulated numerically by taking into account the effects
of gravitational lensing. It is assumed that all of the matter in the universe
takes the form of randomly distributed point masses, each of which has the
identical mass . Calculations are carried out in two extreme cases:
and , where denotes the
wavelength of gravitational waves. In the first case, the distance-redshift
relation for the fully homogeneous and isotropic universe is reproduced with a
small distance dispersion, whereas in the second case, the distance dispersion
is larger. This result suggests that we might obtain information about the
typical mass of lens objects through the distance-redshift relation gleaned
through observation of gravitational waves of various wavelengths. In this
paper, we show how to set limitations on the mass through the observation
of gravitational waves in the clumpy universe model described above.Comment: 35 pages, 21 figures, ApJ accepted versio
Bilirubin as an Anti-oxidant for Surgical Stress: A Preliminary Report of Bilirubin Oxidative Metabolites
Background Bilirubin has been recognized as an antioxidant.
The purpose of this study was to examine
whether bilirubin would act as an antioxidant for
surgical stress in humans. Materials and Methods
Serum bilirubin and urinary bilirubin oxidative
metabolites (BOM) were measured in 96 patients
who underwent surgery. The antioxidant activity
of bilirubin was assessed using BOM measured
by enzyme-linked immunosorbent assay with an
anti-bilirubin monoclonal antibody. Results Serum
bilirubin levels increased after surgery in all 96
patients (p<0.01), but did not correlate with operation
time or blood loss (p=0.53 and p=0.28, respectively).
BOM increased only in patients with major
surgeries (p=0.048). Significant correlations between
BOM and operation time and blood loss were found
(p<0.01). Conclusions Bilirubin appears to act as an
antioxidant for invasive surgery in humans. Urinary
BOM could be a reliable marker for the degree of
surgical stress
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