985 research outputs found
ESR applications to meteorite samples
Electron spin resonance (ESR) measurements were performed on several meteorites. Preliminary results demonstrate some significant features. After the magnetic separation of powdered samples, some of ESR measurements gave ferromagnetic resonance-type spectra similar to the lunar soils. ESR spectra, presumably associated with radiation-induced defects, were observed in Allan Hills-765 and the CAI portion of the Allende meteorite
Early Spectral Evolution of the Rapidly Expanding Type Ia SN 2006X
We present optical spectroscopic and photometric observations of Type Ia
supernova (SN) 2006X from --10 to +91 days after the -band maximum. This SN
exhibits one of the highest expansion velocity ever published for SNe Ia. At
premaximum phases, the spectra show strong and broad features of
intermediate-mass elements such as Si, S, Ca, and Mg, while the O{\sc
i}7773 line is weak. The extremely high velocities of Si{\sc ii} and
S{\sc ii} lines and the weak O{\sc i} line suggest that an intense
nucleosynthesis might take place in the outer layers, favoring a delayed
detonation model. Interestingly, Si{\sc ii}5972 feature is quite
shallow, resulting in an unusually low depth ratio of Si{\sc ii}5972
to 6355, (Si{\sc ii}). The low (Si{\sc ii}) is usually
interpreted as a high photospheric temperature. However, the weak Si{\sc
iii}4560 line suggests a low temperature, in contradiction to the low
(Si{\sc ii}). This could imply that the Si{\sc ii}5972 line
might be contaminated by underlying emission. We propose that (Si{\sc
ii}) may not be a good temperature indicator for rapidly expanding SNe Ia at
premaximum phases.Comment: 20 pages, 7 figures, (Received 2008 August 17; Accepted 2009 April
13
Quantum Field Theoretical Description of Unstable Behavior of Trapped Bose-Einstein Condensates with Complex Eigenvalues of Bogoliubov-de Gennes Equations
The Bogoliubov-de Gennes equations are used for a number of theoretical works
on the trapped Bose-Einstein condensates. These equations are known to give the
energies of the quasi-particles when all the eigenvalues are real. We consider
the case in which these equations have complex eigenvalues. We give the
complete set including those modes whose eigenvalues are complex. The quantum
fields which represent neutral atoms are expanded in terms of the complete set.
It is shown that the state space is an indefinite metric one and that the free
Hamiltonian is not diagonalizable in the conventional bosonic representation.
We introduce a criterion to select quantum states describing the metastablity
of the condensate, called the physical state conditions. In order to study the
instability, we formulate the linear response of the density against the
time-dependent external perturbation within the regime of Kubo's linear
response theory. Some states, satisfying all the physical state conditions,
give the blow-up and damping behavior of the density distributions
corresponding to the complex eigenmodes. It is qualitatively consistent with
the result of the recent analyses using the time-dependent Gross-Pitaevskii
equation.Comment: 29 page
Iso-singlet Down Quark Mixing And CP Violation Experiments
We confront the new physics models with extra iso-singlet down quarks in the
new CP violation experimental era with and
measurements, events, and
limits. The closeness of the new experimental results to the standard
model theory requires us to include full SM amplitudes in the analysis. In
models allowing mixing to a new isosinglet down quark, as in E, flavor
changing neutral currents are induced that allow a mediated contribution
to mixing and which bring in new phases. In ,
, and plots we still find much
larger regions in the four down quark model than in the SM, reaching down to
, , , and down to zero, all at 1. We elucidate
the nature of the cancellation in an order four down quark mixing
matrix element which satisfies the experiments and reduces the number of
independent angles and phases. We also evaluate tests of unitarity for the
CKM submatrix.Comment: 14 pages, 16 figures, REVTeX
IgA and Differentiation-associated Transcription Factors in Chronic Otitis Media with Effusion
ObjectivesInadequate antibody responses to pathogens may lead to the recurrence of otitis media with effusion (OME). Although B-cell production by antibodies is controlled by transcription factors, the status of these factors has not been assessed in patients with OME.MethodsExpression of immunoglobulin was measured by enzyme-linked immunosorbent assay. Expression of transcription factors Bcl-6, Blimp-1, Pax-5, and XBP-1 was assessed by RT-PCR in the middle-ear fluid of 29 children with >4 OME episodes in 12 months or >3 episodes in 6 months (the OME-prone group) and in 32 children with <3 OME episodes in 12 months (OME group). The relationship between recurrence of OME and expression levels of immunoglobulins and transcription factors in middle-ear fluid was determined.ResultsThe concentration of IgA in middle-ear fluid was significantly lower in the OME-prone than in the OME group, as was the expression of mRNA encoding the transcription factors Blimp-1 and XBP-1 (P<0.05 each). Expression of mRNA encoding the transcription factors Bcl-6 and Pax-5 was more intense in the OME-prone than in the OME group, but these differences were not significant (P>0.05).ConclusionLower concentrations of IgA, Blimp-1 and XBP-1 in middle ear fluid of patients with OME may be related to OME recurrence and chronicity
Home intravenous antibiotic treatment for intractable cholangitis in patients with biliary atresia following Kasai portoenterostomies
PURPOSE: Patients with biliary atresia (BA) treated with Kasai portoenterostomy may later develop intractable cholangitis (IC) that is unresponsive to routine conservative treatment. It may cause biliary cirrhosis and eventually hepatic failure with portal hypertension. Control of IC requires prolonged hospitalization for the administration of intravenous antibiotics. To reduce the hospitalization period, we designed a home intravenous antibiotic treatment (HIVA) which can be administered after initial inpatient treatment. In this study, we reviewed the effects of this treatment. METHODS: We reviewed medical records of 10 patients treated with HIVA for IC after successful Kasai portoenterostomies performed for BA between July 1997 and June 2009. RESULTS: The duration of HIVA ranged from 8 to 39 months (median, 13.5 months). The median length of hospital stay was 5.7 days per month for conventional treatments to manage IC before HIVA and, 1.5 days per month (P = 0.012) after HIVA. The median amount of medical expenses per month was reduced by about one tenth with HIVA. One patient underwent liver transplantation due to uncontrolled esophageal variceal bleeding, but the other nine patients had acceptable hepatic function with native livers. CONCLUSION: HIVA may be an effective primary treatment for IC after Kasai portoenterostomies for BA, and reduce length of hospital stay and medical expenseope
Detailed electronic structure studies on superconducting MgB and related compounds
In order to understand the unexpected superconducting behavior of MgB
compound we have made electronic structure calculations for MgB and closely
related systems. Our calculated Debye temperature from the elastic properties
indicate that the average phonon frequency is very large in MgB compared
with other superconducting intermetallics and the exceptionally high in
this material can be explained through BCS mechanism only if phonon softening
occurs or the phonon modes are highly anisotropic. We identified a
doubly-degenerate quasi-two dimensional key-energy band in the vicinity of
along -A direction of BZ which play an important role in
deciding the superconducting behavior of this material. Based on this result,
we have searched for similar kinds of electronic feature in a series of
isoelectronic compounds such as BeB, CaB, SrB, LiBC and
MgBC and found that MgBC is one potential material from the
superconductivity point of view. There are contradictory experimental results
regarding the anisotropy in the elastic properties of MgB ranging from
isotropic, moderately anisotropic to highly anisotropic. In order to settle
this issue we have calculated the single crystal elastic constants for MgB
by the accurate full-potential method and derived the directional dependent
linear compressibility, Young's modulus, shear modulus and relevant elastic
properties. We have observed large anisotropy in the elastic properties. Our
calculated polarized optical dielectric tensor shows highly anisotropic
behavior even though it possesses isotropic transport property. MgB
possesses a mixed bonding character and this has been verified from density of
states, charge density and crystal orbital Hamiltonian population analyses
Role of Ag doping in Ba8Si46 compounds
The silicon clathrate compound Ba8Si46 shows superconductivity below the critical temperature (Tc) of 8K, and the Tc decreases monotonically with doping Ag. In order to reveal effects of Ag doping on the electronic states, we have applied soft x-ray photoemission spectroscopy to Ag-doped silicon clathrate compounds Ba8AgxSi46-x (x=0,1,3,6). The valence band photoemission spectra show that a Ba 5d-derived state at the Fermi level (EF), which is prominently observed in Ba8Si46, decreases with increasing Ag content. The reduction in the peak intensity at EF with increasing Ag content is therefore in accord with the decrease of Tc in Ba8AgxSi46-x. Band structure calculation using local-density approximation reproduces the observed valence band spectra of x=0 and 6. The Si 2p and Ba 4d core-level photoemission spectra demonstrate that the valence electron of Si is attracted to the Ag site in x=1 and the 5d electron of Ba inside the Si24 cage is further donated to Ag in x≥3. Hence, Ag doping leads to the reduction of the peak at EF
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