3,895 research outputs found
Speciation in the baboon and its relation to gamma-chain heterogeneity and to the response to induction of HbF by 5-azacytidine
In the baboon (Papio species), the two nonallelic gamma-genes produce gamma-chains that differ at a minimum at residue 75, where isoleucine (I gamma-chain) or valine (V gamma) may be present. This situation obtains in baboons that are sometimes designated as Papio anubis, Papio hamadryas, and Papio papio. However, in Papio cynocephalus, although the I gamma-chains are identical with those in the above mentioned types, the V gamma-chains have the substitutions ala----gly at residue 9 and ala----val at residue 23. The V gamma-chains of P. cynocephalus are called V gamma C to distinguish them from the V gamma A-chains of P. anubis, etc. A single cynocephalus animal has been found to have only normal I gamma-chains and I gamma C-chains (that is, glycine in residue 9, valine in 23, and isoleucine in 75). When HbF is produced in response to stress with 5-azacytidine, P. anubis baboons respond with greater production than do P. cynocephalus, and hybrids fall between. Minimal data on P. hamadryas and P. papio suggest an even lower response than P. cynocephalus. As HbF increases under stress, the ratio of I gamma to V gamma-chains changes from the value in the adult or juvenile baboon toward the ratio in the newborn baboon. However, it does not attain the newborn value. The V gamma A and V gamma C-genes respond differently to stress. In hybrids, the production of V gamma A- chains exceeds that of V gamma C-chains. A controlling factor in cis apparently is present and may be responsible for the species-related extent of total HbF production. It may be concluded that the more primitive the cell in the erythroid maturation series that has been subjected to 5-azacytidine, the more active is the I gamma-gene
Unveiling Su Aurigae in the near Infrared: New high spatial resolution results using Adaptive Optics
We present here new results on circumstellar nebulosity around SU Aurigae, a
T-Tauri star of about 2 solar mass and 5 Myrs old at 152 pc in the J, H and K
bands using high resolution adaptive optics imaging (0\farcs30) with the Penn
state IR Imaging Spectrograph (PIRIS) at the 100 inch Mt. Wilson telescope.
A comparison with HST STIS optical (0.2 to 1.1 micron) images shows that the
orientation of the circumstellar nebulosity in the near-IR extends from PAs 210
to 270 degrees in H and K bands and up to 300 degrees in the J band. We call
the circumstellar nebulosity seen between 210 to 270 degrees as 'IR
nebulosity'. We find that the IR nebulosity (which extends up to 3.5 arcsecs in
J band and 2.5 arcsecs in the K band) is due to scattered light from the
central star. The IR nebulosity is either a cavity formed by the stellar
outflows or part of the circumstellar disk. We present a schematic
3-dimensional geometrical model of the disk and jet of SU Aur based on STIS and
our near-IR observations. According to this model the IR nebulosity is a part
of the circumstellar disk seen at high inclination angles. The extension of the
IR nebulosity is consistent with estimates of the disk diameter of 50 to 400 AU
in radius, from earlier mm, K band interferometric observations and SED
fittings.Comment: Accepted for publications in the Astronomical Journal, to appear in
the May issue of the Journa
D-Terms from Generalized NS-NS Fluxes in Type II
Orientifolds of type II string theory admit a certain set of generalized
NS-NS fluxes, including not only the three-form field strength H, but also
metric and non-geometric fluxes, which are related to H by T-duality. We
describe in general how these fluxes appear as parameters of an effective N=1
supergravity theory in four dimensions, and in particular how certain
generalized NS-NS fluxes can act as charges for R-R axions, leading to D-term
contributions to the effective scalar potential. We illustrate these phenomena
in type IIB with the example of a certain orientifold of T^6/Z_4.Comment: 31+1 pages, uses utarticle.cls; v2: references adde
An Effective Theory for Midgap States in Doped Spin Ladder and Spin-Peierls Systems: Liouville Quantum Mechanics
In gapped spin ladder and spin-Peierls systems the introduction of disorder,
for example by doping, leads to the appearance of low energy midgap states. The
fact that these strongly correlated systems can be mapped onto one dimensional
noninteracting fermions provides a rare opportunity to explore systems which
have both strong interactions and disorder. In this paper we show that the
statistics of the zero energy midgap wave functions in these models can be
effectively described by Liouville Quantum Mechanics. This enables us to
calculate the disorder averaged N-point correlation functions of these states
(the explicit calculation is performed for N=2,3). We find that whilst these
midgap states are typically weakly correlated, their disorder averaged
correlation are power law. This discrepancy arises because the correlations are
not self-averaging and averages of the wave functions are dominated by
anomalously strongly correlated configurations.Comment: 13 page latex fil
Testosterone Levels in Men with Chronic Migraine
Chronic migraine is a frequent and debilitating condition affecting 14% of the general population. This prospective observational pilot study investigated whether men with chronic migraine have lower than expected total serum testosterone levels. We identified 14 men ages 26-51 at our Institution who fulfilled the ICHD-3b criteria for chronic migraine and obtained serum total testosterone levels. The mean total testosterone level in our 14 patients was 322 ng/dL (range: 120-542 ng/dL) which is in the lower 5% of the reference range for our laboratory (300-1080 ng/dL). Men with chronic migraine had lower total testosterone levels compared to published agematched normative median values by a median difference of 62 ng/dL (P=0.0494). This finding suggests that hypothalamic regulation is altered in patients with chronic migraine. Further studies are warranted to determine whether testosterone supplementation in men with chronic migraine reduces the number of headaches or the associated symptoms of hypogonadism
High definition systems in Japan
The successful implementation of a strategy to produce high-definition systems within the Japanese economy will favorably affect the fundamental competitiveness of Japan relative to the rest of the world. The development of an infrastructure necessary to support high-definition products and systems in that country involves major commitments of engineering resources, plants and equipment, educational programs and funding. The results of these efforts appear to affect virtually every aspect of the Japanese industrial complex. The results of assessments of the current progress of Japan toward the development of high-definition products and systems are presented. The assessments are based on the findings of a panel of U.S. experts made up of individuals from U.S. academia and industry, and derived from a study of the Japanese literature combined with visits to the primary relevant industrial laboratories and development agencies in Japan. Specific coverage includes an evaluation of progress in R&D for high-definition television (HDTV) displays that are evolving in Japan; high-definition standards and equipment development; Japanese intentions for the use of HDTV; economic evaluation of Japan's public policy initiatives in support of high-definition systems; management analysis of Japan's strategy of leverage with respect to high-definition products and systems
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