14 research outputs found
Scaling Relations for Collision-less Dark Matter Turbulence
Many scaling relations are observed for self-gravitating systems in the
universe. We explore the consistent understanding of them from a simple
principle based on the proposal that the collision-less dark matter fluid terns
into a turbulent state, i.e. dark turbulence, after crossing the caustic
surface in the non-linear stage. The dark turbulence will not eddy dominant
reflecting the collision-less property. After deriving Kolmogorov scaling laws
from Navier-Stokes equation by the method similar to the one for Smoluchowski
coagulation equation, we apply this to several observations such as the
scale-dependent velocity dispersion, mass-luminosity ratio, magnetic fields,
and mass-angular momentum relation, power spectrum of density fluctuations.
They all point the concordant value for the constant energy flow per mass: , which may be understood as the speed of the hierarchical
coalescence process in the cosmic structure formation.Comment: 26 pages, 6 figure
Promoting Effects of Sucrose-rich Diet on N-Nitrosobis (2-oxopropyl) amine-induced Pancreatic Carcinogenesis in Hamsters
It has been reported that there is an association between pancreatic cancer
and obesity, impaired glucose metabolism and diabetes based on excess
dietary fat and sugar intakes. A number of studies have suggested that a
high-fat diet increases development of carcinomas in various organs and
possible risk factors for pancreatic cancer. However, how an excess sugar
intake promotes pancreatic carcinogenesis is still unknown. In the present
study, we investigated the influence of an excess sugar intake on
pancreatic carcinogenesis by administration of a sucrose-rich diet in which
starch was replaced by sucrose in order to contain the same calories and
other nutrients. Two similar experiments were performed. Six-week-old male
Syrian golden hamsters were given N-nitrosobis (2-oxopropyl) amine (BOP) at
a dose of 50 and 20 mg/kg body weight as a carcinogen in Week 0 and 1,
respectively. In Week 2, the animals were divided into control and
experimental groups. In experiment 1, 15 animals received a control diet or
sucrose-rich diet in which 100% of the starch was replaced by sucrose,
respectively. Since five animals fed on the sucrose-rich diet died by Week
12, the diet was changed to a sucrose-rich diet in which 50% of the starch
was replaced by sucrose. In experiment 2, 15 animals received a control
diet or sucrose-rich diet in which 50 or 20% of the starch was replaced by
sucrose, respectively. All animals were sacrificed 25 weeks after the start
of the experiment, and histological examination of the pancreas was
performed. No significant difference was seen in the body weight at the end
of the experiment. There were no significant differences in the
glycosylated hemoglobin (HbA1c) and serum triglyceride, total cholesterol
and HDL-cholesterol levels between the control and sucrose-rich diet groups
in experiments 1 and 2. The incidence and number of carcinomas increased in
hamsters fed the sucrose-rich diet compared with the control diet in
experiments 1 and 2. These results suggest that an excess sucrose intake
may promote the development of pancreatic cancer in hamsters
Topological 2-form Gravity in Four Dimensions
A kind of topological field theory is proposed as a candidate to describe the
global structure of the 2-form Einstein gravity with or without a cosmological
constant. Indeed in the former case, we show that a quantum state in the
candidate gives an exact solution of the Wheeler-DeWitt equation. The BRST
quantization based on the Batalin-Fradkin-Vilkovisky (BFV) formalism is carried
out for this topological version of the 2-form Einstein gravity.Comment: 15 page
Herbig Ae/Be Stars in the Magellanic Bridge
We have found Herbig Ae/Be star candidates in the western region of the
Magellanic Bridge. Using the near infrared camera SIRIUS and the 1.4 m
telescope IRSF, we surveyed about 3.0 deg x 1.3 deg (24 deg < RA < 36 deg, -75
deg < Dec. < -73.7 deg) in the J, H, and Ks bands. On the basis of colors and
magnitudes, about 200 Herbig Ae/Be star candidates are selected. Considering
the contaminations by miscellaneous sources such as foreground stars and
early-type dwarfs in the Magellanic Bridge, we estimate that about 80 (about
40%) of the candidates are likely to be Herbig Ae/Be stars. We also found one
concentration of the candidates at the young star cluster NGC 796, strongly
suggesting the existence of pre-main-sequence (PMS) stars in the Magellanic
Bridge. This is the first detection of PMS star candidates in the Magellanic
Bridge, and if they are genuine PMS stars, this could be direct evidence of
recent star formation. However, the estimate of the number of Herbig Ae/Be
stars depends on the fraction of classical Be stars, and thus a more precise
determination of the Be star fraction or observations to differentiate between
the Herbig Ae/Be stars and classical Be stars are required.Comment: 22 pages, 6 figures. Accepted for publication in Ap
Gravitational Instantons and Moduli Spaces of Topological 2-form Gravity
A topological version of four-dimensional (Euclidean) Einstein gravity which
we propose regards anti-self-dual 2-forms and an anti-self-dual part of the
frame connections as fundamental fields. The theory describes the moduli spaces
of conformally self-dual Einstein manifolds for the non-zero cosmological
constant case and Einstein-Kahlerian manifold with the vanishing real first
Chern class for the zero cosmological constant. In the non-zero cosmological
constant case, we evaluate the index of the elliptic complex associated with
the moduli space and calculate the partition function. We also clarify the
moduli space and its dimension for the zero cosmological constant case which
are related to the Plebansky's heavenly equations.Comment: 36pages, LaTex, TIT/HEP-247/COSMO-4