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Expression of natural killer receptor alleles at different Ly49 loci occurs independently and is regulated by major histocompatibility complex class I molecules.
Ly49 receptor genes are expressed by subsets of natural killer (NK) cells in an overlapping fashion, accounting for the capacity of NK subsets to attack host cells that have selectively downregulated self-major histocompatibility complex (MHC) class I molecules. It was shown previously that most NK cells express only one or the other allele of a given Ly49 gene, while a smaller population expresses both alleles. However, the methods used to detect monoallelic and biallelic cells were nonquantitative. Here, new allele-specific antibodies were used to provide the first quantitative examination of biallelic and monoallelic expression of Ly49A and Ly49G2. The results demonstrate conclusively that most Ly49A(+) and Ly49G2(+) NK cells express the corresponding gene in a monoallelic fashion, with a smaller subset expressing both alleles. Unexpectedly, biallelic Ly49A(+) NK cells were more numerous than predicted by completely independent allelic expression, suggesting some heterogeneity among NK progenitors in the potential to express a given Ly49 gene. The data also show that cells expressing one allele of Ly49G2 may express Ly49A from the same or opposite chromosome with equal likelihood, indicating that the expressed allele is chosen independently for different Ly49 genes. Finally, the data demonstrate that biallelic expression of Ly49A or Ly49G2 occurs least frequently in mice that express ligands for these receptors (H-2(d) mice), and most frequently in class I-deficient mice. Thus, biallelic expression of Ly49 genes is regulated by interactions of NK cell progenitors with MHC class I molecules
A note on the calculation of the effective range
The closed form of the first order non-linear differential equation that is
satisfied by the effective range within the variable phase formulation of
scattering theory is discussed. It is shown that the conventional method of
determining the effective range, by fitting a numerical solution of the
Schr\"odinger equation to known asymptotic boundary conditions, can be modified
to include the first order contribution of a long range interaction.Comment: 4 page
Molecular-beam epitaxy of CrSi_2 on Si(111)
Chromium disilicide layers have been grown on Si(111) in a commercial molecularâbeam epitaxy machine. Thin layers (10 nm) exhibit two epitaxial relationships, which have been identified as CrSi_2(0001)//Si(111) with CrSi_2[1010]//Si[101], and CrSi_2(0001)//Si(111) with CrSi_2[1120]//Si[101]. The latter case represents a 30° rotation of the CrSi_2 layer about the Si surface normal relative to the former case. Thick (210 nm) layers were grown by four different techniques, and the bestâquality layer was obtained by codeposition of Cr and Si at an elevated temperature. These layers are not single crystal; the largest grains are observed in a layer grown at 825â°C and are 1â2 ÎŒm across
Disentangling the exchange coupling of entangled donors in the Si quantum computer architecture
We develop a theory for micro-Raman scattering by single and coupled
two-donor states in silicon. We find the Raman spectra to have significant
dependence on the donor exchange splitting and the relative spatial positions
of the two donor sites. In particular, we establish a strong correlation
between the temperature dependence of the Raman peak intensity and the
interdonor exchange coupling. Micro-Raman scattering can therefore potentially
become a powerful tool to measure interqubit coupling in the development of a
Si quantum computer architecture.Comment: Title changed. Other minor change
ANALISIS KEUNTUNGAN USAHA TANI BUDIDAYA IKAN NILA GIFT DI DESA LEMBONG URAM KECAMATAN LEBONG UTARA KABUPATEN LEBONG
Fishery cultIvation is one sub-sector which is really potential to be
developed because it is to be renewed. Lebong Regency also have the potential to
develop the fisheries sector especially in embong uram village north lebong sub-
distrct lebong regency. The Fishery cultivation that developed in this place is nila
gift fish. the purpose of the research is to know how io count the profits of
cultivation of nila gift fish in embong uram village north lebong sub-district
lebong regency with number of respondents are 20 persons. The results obtained
by the nila gift fish stable price is in range of Rp.2O.OO0 with the production of
nila gift fish 40 kg while the lowest to the highest level of production is 300 kg.
For total fixed cost (TFC) in the range of Rp. 460.000 for the lowest and the
highest total fixed cost Rp. 5.800.000. while tn Total variable cost (TVC) that
incurred by farmers in average Rp 200.000. The, crop cultivation of nila gift fish
in embong uram village north lebong sub-district lebong regency most benefit by
the range is the lowest profit obtained Rp. 140.000 and tte nighest Rp. 2.425.000
but there is also the farmer who suffer losses of that is as much as 1 people with
losses of Rp. 3.600.000 and a farmer has break even point which revenue as same
as total cost.
Key Words: price, production, cost and profi
Synthesis and fluorescent properties of ÎČ-pyridyl α-amino acids
The preparation of a new class of ÎČ-pyridyl α-amino acid is described using a highly regioselective, ytterbium-catalyzed hetero Diels-Alder reaction of enones with vinyl ethers followed by a modified Knoevenagel-Stobbe reaction as the key heterocycle forming steps. Investigation of the properties and applications of these amino acids showed that they could be utilized in solid phase peptide synthesis for the preparation of a biologically relevant hexapeptide, while pyridines bearing electron-rich substituents exhibited strongly fluorescent properties with high quantum yields and MegaStokes shifts. A solvatochromic study with the most fluorogenic amino acid, a p-methoxyphenyl analogue revealed that this charge-transfer based chromophore is highly sensitive to solvent polarity with a bathochromic shift of 115 nm on changing from THF to phosphate-buffered saline
The variable phase method used to calculate and correct scattering lengths
It is shown that the scattering length can be obtained by solving a Riccati
equation derived from variable phase theory. Two methods of solving it are
presented. The equation is used to predict how long-range interactions
influence the scattering length, and upper and lower bounds on the scattering
length are determined. The predictions are compared with others and it is shown
how they may be obtained from secular perturbation theory.Comment: 7 pages including 3 figure
Pressure-induced metallization in solid boron
Different phases of solid boron under high pressure are studied by first
principles calculations. The -B structure is found to be stable
up to 270 GPa. Its semiconductor band gap (1.72 eV) decreases continuously to
zero around 160 GPa, where the material transforms to a weak metal. The
metallicity, as measured by the density of states at the Fermi level, enhances
as the pressure is further increased. The pressure-induced metallization can be
attributed to the enhanced boron-boron interactions that cause bands overlap.
These results are consist with the recently observed metallization and the
associated superconductivity of bulk boron under high pressure (M.I.Eremets et
al, Science{\bf 293}, 272(2001)).Comment: 14 pages, 5 figure
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