1,396 research outputs found
On Conway-Gordon type theorems for graphs in the Petersen family
For every spatial embedding of each graph in the Petersen family, it is known
that the sum of the linking numbers over all of the constituent 2-component
links is congruent to 1 modulo 2. In this paper, we give an integral lift of
this formula in terms of the square of the linking number and the second
coefficient of the Conway polynomial.Comment: 13 pages, 5 figures. arXiv admin note: text overlap with
arXiv:1104.082
Permeability-control on volcanic hydrothermal system: case study for Mt. Tokachidake, Japan, based on numerical simulation and field observation
We investigate a volcanic hydrothermal system by using numerical simulation with three key observables as reference: the magnetic total field, vent temperature, and heat flux. We model the shallow hydrothermal system of Mt. Tokachidake, central Hokkaido, Japan, as a case study. At this volcano, continuous demagnetization has been observed since at least 2008, suggesting heat accumulation beneath the active crater area. The surficial thermal manifestation has been waning since 2000. We perform numerical simulations of heat and mass flow within a modeled edifice at various conditions and calculate associated magnetic total field changes due to the thermomagnetic effect. We focus on the system’s response for up to a decade after permeability is reduced at a certain depth in the modeled conduit. Our numerical simulations reveal that (1) conduit obstruction (i.e., permeability reduction in the conduit) tends to bring about a decrease in vent temperature and heat flux, as well as heat accumulation below the level of the obstruction, (2) the recorded changes cannot be consistently explained by changing heat supply from depth, and (3) caprock structure plays a key role in controlling the location of heating and pressurization. Although conduit obstruction may be caused by either physical or chemical processes in general, the latter seems more likely in the case of Mt. Tokachidake
Near-Infrared Imaging Polarimetry of S106 Cluster-Forming Region with SIRPOL
We present the results of wide-field JHKs polarimetry toward the HII region
S106 using the IRSF (Infrared Survey Facility) telescope. Our polarimetry data
revealed an extended (up to ~ 5') polarized nebula over S106. We confirmed the
position of the illuminating source of most of the nebula as consistent with
S106 IRS4 through an analysis of polarization vectors. The bright portion of
the polarized intensity is consistent with the red wing component of the
molecular gas. Diffuse polarized intensity emission is distributed along the
north--south molecular gas lanes. We found the interaction region between the
radiation from S106 IRS4 and the dense gas. In addition, we also discovered two
small polarization nebulae, SIRN1 and SIRN2, associated with a young stellar
objects (YSO). Aperture polarimetry of point-like sources in this region was
carried out for the first time. The regional magnetic field structures were
derived using point-like source aperture polarimetry, and the magnetic field
structure position angle around the cluster region in S106 was found to be ~
120\arcdeg. The magnetic fields in the cluster region, however, have three
type position angles: ~ 20\arcdeg, ~ 80\arcdeg, and ~ 120\arcdeg. The
present magnetic field structures are consistent with results obtained by
submillimeter continuum observations. We found that the magnetic field
direction in the dense gas region is not consistent with that of the low
density gas region.Comment: 22 pages, 11 figures, accepted for publication in A
Near-Infrared Imaging Polarimetry of the Serpens Cloud Core: Magnetic Field Structure, Outflows, and Inflows in A Cluster Forming Clump
We made deep NIR imaging polarimetry toward the Serpens cloud core. The
polarization vector maps enable us to newly detect 24 small IR reflection
nebulae with YSOs. Polarization measurements of NIR point sources indicate an
hourglass-shaped magnetic field, of which symmetry axis is nearly perpendicular
to the elongation of the C18O (J=1-0) or submillimeter continuum emission. The
bright part of C18O (J=1-0), submillimeter continuum cores as well as many
class 0/I objects are located just toward the constriction region of the
hourglass-shaped magnetic field. Applying the CF method, the magnetic field
strength was estimated to be ~100 muG, suggesting that the ambient region of
the Serpens cloud core is moderately magnetically supercritical. These suggest
that the Serpens cloud core first contracted along the magnetic field to be an
elongated cloud, which is perpendicular to the magnetic field, and that then
the central part contracted cross the magnetic field due to the high density in
the central region of the cloud core, where star formation is actively
continuing. Comparison of this magnetic field with the previous observations of
molecular gas and large-scale outflows suggests a possibility that the cloud
dynamics is controlled by the magnetic field, protostellar outflows and
gravitational inflows. This appears to be in good agreement with the
outflow-driven turbulence model and implies the importance of the magnetic
field to continuous star formation in the center region of the cluster forming
region.Comment: 36 pages, 11 figures, 2 tables, accepted for publication in the
Astrophysical Journa
A facile synthetic method of α-quaternary-β,γ-unsaturated aldehydes via the stereoselective 1,4-elimination and α-regioselective Ferrier reaction
The 1,4-elimination reaction of 2-substituted-(2Z)-4-methoxy-O-alkenyl acetals with n-butyllithium is shown to afford the 2-substituted-(1Z,3E)-O-1,3-dienyl acetals in high stereoselectivities. The Ferrier reaction of the O-1,3-dienyl acetals thus obtained provides the corresponding α-quaternary-β,γ-unsaturated aldehydes in excellent yields with high α-regioselectivities.journal articl
Lamivudine treatment in patients with HBV-related hepatocellular carcinoma--using an untreated, matched control cohort.
Lamivudine is widely used to treat patients with hepatitis B. However, the outcomes in patients with hepatocellular carcinoma (HCC) treated with lamivudine have not been established. This study was conducted to evaluate the outcomes of lamivudine treatment for patients with HCC using an untreated, matched control group. Thirty patients with controlled HCC orally received lamivudine. As controls, 40 patients with HCC who were not treated with lamivudine and matched for clinical features were selected. The lamivudine-treated and untreated groups were compared with respect to changes in liver function, HCC recurrence, survival, and cause of death. In the lamivudine-treated group, there was significant improvement in the Child-Pugh score at 24 months after starting treatment, while no improvement was observed in the untreated group. There was no significant difference in the cumulative incidence of HCC recurrence and survival between the groups. However, there was a significant difference in the cumulative incidence of death due to liver failure (P= 0.043). A significant improvement in liver function was achieved by lamivudine treatment, even in patients with HCC. These results suggest that lamivudine treatment for patients with HCC may prevent death due to liver failure. Further prospective randomized studies using a larger number of patients are required.</p
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