38 research outputs found
Anisotropic structural and optical properties of a-plane (11-20) AlInN nearly-lattice-matched to GaN
We report epitaxial growth of a-plane (11-20) AlInN layers
nearly-lattice-matched to GaN. Unlike for c-plane oriented epilayers, a-plane
Al_{1-x}In_{x}N cannot be simultaneously lattice-matched to GaN in both
in-plane directions. We study the influence of temperature on indium
incorporation and obtain nearly-lattice-matched Al_{0.81}In_{0.19}N at a growth
temperature of 760^{o}C. We outline a procedure to check in-plane lattice
mismatch using high resolution x-ray diffraction, and evaluate the strain and
critical thickness. Polarization-resolved optical transmission measurements of
the Al_{0.81}In_{0.19}N epilayer reveal a difference in bandgap of ~140 meV
between (electric field) E_parallel_c [0001]-axis and E_perpendicular_c
conditions with room-temperature photoluminescence peaked at 3.38 eV strongly
polarized with E_parallel_c, in good agreement with strain-dependent
band-structure calculations
Search for the radiative decay in the SND experiment at VEPP-2M
The decay was investigated by the SND detector
at VEPP-2M collider in the reaction .
Here we present the results and some details of this study. We report an upper
limit (90% c.l.) as our
final result. Our upper limit does not contradict the earlier measurement by
GAMS spectrometer. To facilitate future studies a rather detailed review of the
problem is also given.Comment: 24 pages, 6 figures, LaTex. To be published in Nucl. Phys.
Modeling the Subsurface Structure of Sunspots
While sunspots are easily observed at the solar surface, determining their
subsurface structure is not trivial. There are two main hypotheses for the
subsurface structure of sunspots: the monolithic model and the cluster model.
Local helioseismology is the only means by which we can investigate
subphotospheric structure. However, as current linear inversion techniques do
not yet allow helioseismology to probe the internal structure with sufficient
confidence to distinguish between the monolith and cluster models, the
development of physically realistic sunspot models are a priority for
helioseismologists. This is because they are not only important indicators of
the variety of physical effects that may influence helioseismic inferences in
active regions, but they also enable detailed assessments of the validity of
helioseismic interpretations through numerical forward modeling. In this paper,
we provide a critical review of the existing sunspot models and an overview of
numerical methods employed to model wave propagation through model sunspots. We
then carry out an helioseismic analysis of the sunspot in Active Region 9787
and address the serious inconsistencies uncovered by
\citeauthor{gizonetal2009}~(\citeyear{gizonetal2009,gizonetal2009a}). We find
that this sunspot is most probably associated with a shallow, positive
wave-speed perturbation (unlike the traditional two-layer model) and that
travel-time measurements are consistent with a horizontal outflow in the
surrounding moat.Comment: 73 pages, 19 figures, accepted by Solar Physic
Evolution of texture and microstructure in a thermomechanically processed Al-Li-Cu-Mg alloy
Epstein-Barr virus and HLA-DPB1-*0301 in young adult Hodgkin's disease: Evidence for inherited susceptibility to Epstein-Barr virus in cases that are EBV+ve
Cases of Hodgkin’s disease (HD) may be distinguished by whether they do [EBV-positive ((+ve)) cases] or do not [EBV-negative ((-ve)) cases] have evidence of EBV DNA in the Reed-Sternberg cells. Only one study has attempted to distinguish epidemiological risk factors for EBV+ve and EBV-ve HD, and none have compared inherited susceptibility. The present study involves a population-based case series of HD, diagnosed in patients between 16-24 years of age in the United Kingdom (n = 118), of whom 87% were classified by EBV status (EBV+ve, 19, EBV-ve, 84). History of infectious illness, EBV antibody titers, and HLA-DPB1 type have been compared in EBV+ve and EBV-ve cases. Reported infectious mononucleosis was more frequent in EBV+ve cases (odds ratio (OR), 5.10; 95% confidence interval (CI), 1.12-24.4). EBV antibody titers to viral capsid antigen were significantly higher in EBV+ve cases (P for trend = 0.02). Higher proportions of EBV+ve (43%) than EBV-ve (31%) cases typed positive for HLA-DPB1*0301, but this was not statistically significant; the association of infectious mononucleosis with EBV+ve cases was stronger in this HLA subgroup (OR, 17.1; 95%CI, 1.06-1177) than in other cases (OR, 1.24; 95% CI, 0.02-15.4). Although these results are based on small numbers of HD cases, they provide suggestive evidence that the etiology of EBV+ve HD may involve inherited susceptibility to EBV