836 research outputs found
Cut loci and conjugate loci on Liouville surfaces
In the earlier paper (Itoh and Kiyohara, Manuscr Math 114:247–264, 2004), we showed that the cut locus of a general point on two-dimensional ellipsoid is a segment of a curvature line and proved "Jacobi’s last geometric statement" on the singularities of the conjugate locus. In the present paper,we showthat a wider class of Liouville surfaces possess such simple cut loci and conjugate loci. The results include the determination of cut loci and the set of poles on two-sheeted hyperboloids and elliptic paraboloids
Magnetic properties of Fe3O4 nanoparticles coated with oleic and dodecanoic acids
Magnetic nanoparticles (NP) of magnetite (Fe3O4) coated with oleic acid (OA)
and dodecanoic acid (DA) were synthesized and investigated through Transmission
Electron Microscopy (TEM),magnetization M, and ac magnetic susceptibility
measurements. The OA coated samples were produced with different magnetic
concentrations (78, 76, and 65%) and the DA sample with 63% of Fe3O4. Images
from TEM indicate that the NP have a nearly spherical geometry and mean
diameter ~ 5.5 nm. Magnetization measurements, performed in zero field cooled
(ZFC) and field cooled (FC) processes under different external magnetic fields
H, exhibited a maximum at a given temperature TB in the ZFC curves, which
depends on the NP coating (OA or DA), magnetite concentration, and H. The
temperature TB decreases monotonically with increasing H and, for a given H,
the increase in the magnetite concentration results in an increase of TB. The
observed behavior is related to the dipolar interaction (DI) between NP which
seems to be an important mechanism in all samples studied. This is supported by
the results of the ac magnetic susceptibility Xac measurements, where the
temperature in which X' peaks for different frequencies follows the
Vogel-Fulcher model, a feature commonly found in systems with dipolar
interactions. Curves of H vs. TB/TB(H=0) for samples with different coatings
and magnetite concentrations collapse into a universal curve, indicating that
the qualitative magnetic behavior of the samples may be described by the NP
themselves, instead of the coating or the strength of the dipolar interaction.
Below TB, M vs. H curves show a coercive field (HC) that increases
monotonically with decreasing temperature. The saturation magnetization (MS)
follows the Bloch's law and values of MS at room temperature as high as 78
emu/g were estimated, a result corresponding to ~80% of the bulk value. The
overlap of M/MS vs. H/T curves for a given sample and the low HC at high
temperatures suggest superparamagnetic behavior in all samples studied. The
overlap of M/MS vs. H curves at constant temperature for different samples
indicates that the NP magnetization behavior is preserved, independently of the
coating and magnetite concentration.Comment: 8 pages and 9 figure
On a family of integrable systems on with a cubic integral of motion
We discuss a family of integrable systems on the sphere with an
additional integral of third order in momenta. This family contains the
Coryachev-Chaplygin top, the Goryachev system, the system recently discovered
by Dullin and Matveev and two new integrable systems. On the non-physical
sphere with zero radius all these systems are isomorphic to each other.Comment: LaTeX, 8 page
Stimulating Effect of Japanese Herbal (Kampo) Medicine, Hochuekkito on Upper Respiratory Mucosal Immune System
Japanese herbal (Kampo) medicine, Hochuekkito (Bu-Zhong-Yi-Qi-Tang in Chinese, TJ-41) and Juzentaihoto (Shi-Quan-Da-Bu-Tang in Chinese, TJ-48) are well-known Kampo formulas used as tonic. Although these medicines have separately been applied to the patients clinically depending on their symptoms, the differences of the pharmacological activities for these medicines have not been fully understood. TJ-48 and TJ-41 were compared for their effects on antibody response in upper respiratory mucosal immune system in vivo. Oral administration of TJ-41 (100 mg kg(−1) per day) to early aged BALB/c mice, which were nasally sensitized with influenza hemagglutinin vaccine, significantly enhanced influenza virus-specific IgA and IgG antibody titers in nasal cavity and sera, respectively. However, oral administration of TJ-48 (100 mg kg(−1) per day) failed to show the enhancing activity. TJ-41 increased not only influenza virus-specific IgA antibody titer but also total IgA antibody titer in nasal cavity. The stimulating activity of TJ-41 disappeared after treatment with methotrexate. The present study strongly suggests that TJ-41 can stimulate the mucosal immune system of upper respiratory tract, and results in enhancement of antigen-specific antibody response in upper respiratory mucosal and systemic immune systems
Gallot-Tanno Theorem for closed incomplete pseudo-Riemannian manifolds and applications
We extend the Gallot-Tanno Theorem to closed pseudo-Riemannian manifolds. It
is done by showing that if the cone over a manifold admits a parallel symmetric
tensor then it is Riemannian. Applications of this result to the
existence of metrics with distinct Levi-Civita connections but having the same
unparametrized geodesics and to the projective Obata conjecture are given. We
also apply our result to show that the holonomy group of a closed
-manifold does not preserve any nondegenerate splitting of
.Comment: minor correction
Effect of Arachidonic Acid-enriched Oil Diet Supplementation on the Taste of Broiler Meat
To elucidate the relationship between the arachidonic acid (AA) content and the taste of broiler meat, the effects of AA-enriched oil (AAO) supplements on the fatty acid content and sensory perceptions of thigh meat were evaluated. Four types of oil, including corn oil (CO), a 1:1 mixture of AAO and palm oil (PO) (1/2 AAO), a 1:3 mixture of AAO and PO (1/4 AAO), and a 1:7 mixture of AAO and PO (1/8 AAO) were prepared. Each type of oil was mixed with silicate at a ratio of 7:3, and added to the diet at a final proportion of 5% of fresh matter. Broiler chickens were fed these diets for 1 wk before slaughter. In thigh meat, the AA content of the 1/2 and 1/4 AAO groups was significantly higher than that of the CO group. The AA content in thigh meat (y, mg/g) increased linearly with increasing dietary AAO content (x, g/100 g of diet), according to the equation y = 0.5674+0.4596× (r2 = 0.8454). The content of other fatty acids was not significantly different among the 4 diet groups. Sensory evaluation showed that the flavor intensity, umami (L-glutamate taste), kokumi (continuity, mouthfulness, and thickness), and aftertaste of the 1/2 and 1/4 AAO groups were significantly higher than that of the CO group. There were significant positive correlations between AA content in thigh meat and the flavor intensity, total taste intensity, umami, and aftertaste. These data suggest that the taste of broiler meat can be improved by the amount of dietary AA supplementation
On one integrable system with a cubic first integral
Recently one integrable model with a cubic first integral of motion has been
studied by Valent using some special coordinate system. We describe the
bi-Hamiltonian structures and variables of separation for this system.Comment: LaTeX with AMS fonts, 9 page
CALCIFICATION IN THE ARTICULATED CORALLINE ALGA CORALLINA-PILULIFERA, WITH SPECIAL REFERENCE TO THE EFFECT OF ELEVATED CO2 CONCENTRATION
Calcification in Corallina pilulifera Postels et Ruprecht displayed diurnal variations in aerated (350 ppm CO2) culture media, with faster rates during the light than during the dark period. Addition of CO2 (air + 1250 ppm) inhibited calcification. This was attributable to the decreased pH resulting from CO2 addition. Both photosynthesis and calcification were enhanced in seawater, with elevated dissolved inorganic carbon concentrations at a constant pH of 8.2
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