Possible Location (possible + location)

Distribution by Scientific Domains


Selected Abstracts


Bounds for the eigenvalues of block 2 × 2 Hermitian positive-definite matrices,

NUMERICAL LINEAR ALGEBRA WITH APPLICATIONS, Issue 5-6 2005
L. Yu.
Abstract Lower and upper conditional bounds for the eigenvalues of a Hermitian positive-definite block 2 × 2 matrix, describing their closest possible location, are derived. The notions of partially and totally optimal spectra are introduced, and several equivalent characterizations of matrices with partially and totally optimal spectra are presented. It is shown that the block 2 × 2 block Jacobi scaled matrices and the so-called equilibrated matrices have totally optimal spectra. Copyright © 2005 John Wiley & Sons, Ltd. [source]


Brachiola algerae Spore Membrane Systems, their Activity During Extrusion, and a New Structural Entity, the Multilayered Interlaced Network, Associated with the Polar Tube and the Sporoplasm

THE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 2 2002
ANN CALI
ABSTRACT. The microsporidial genus, Brachiola, contains three species: the type species Brachiola vesicularum (identified from an AIDS patient) and two species transferred from the genus Nosema, becoming Brachiola connori and Brachiola algerae. A developmental feature of the genus Brachiola is the "thickened" plasmalemma from sporoplasm through sporoblast stage. The sporoplasm has been reported to have a thick plasmalemma at 1-h postextrusion. The purpose of this investigation was to observe B. algerae spores before, during and after germination to determine if the plasmalemma is thick at the point of extrusion and if not, when and how it forms. New understandings regarding the polar filament position inside the spore, places it outside the sporoplasm proper with the sporoplasm limiting membrane imaginations surrounding it. These invaginations, present a possible location for aquaporins. The multilayered interlaced network (MIN), a new organelle (possibly of Golgi origin from the sporoblast), was observed inside the spore and sporoplasm; it formed an attachment to the end of the extruded polar tube and contributed to the thickening of the sporoplasm plasmalemma. A thin "unit limiting membrane", present on the sporoplasm at the time of extrusion, is connected to the MIN by many cross-connections forming the "thick blistered" surface by 30 min-postextrusion. [source]


Localizing the X-linked orange colour phenotype using feline resource families

ANIMAL GENETICS, Issue 1 2005
R. A. Grahn
Summary Many genes influencing mammalian coat colours are well conserved. While genes responsible for pelage phenotypes in one species provide strong evidence for a candidate gene in a different species, the X-linked orange phenotype of the domestic cat is unique within mammals. The orange locus (O) undergoes X-inactivation, producing females that express both wildtype black (wt) and orange (variant) phenotypes when heterozygous (tortoiseshell). The orange locus has not yet been localized on the X chromosome. Tortoiseshell male cats have been identified but have been shown to be sex chromosome trisomies (XXY). To localize the cat orange locus, 10 feline-derived X-linked microsatellites were analysed in two extended cat pedigrees consisting of 79 and 55 individuals, respectively, segregating for the orange phenotype. Linkage analyses excluded close association of orange in the vicinity of the nine informative X-linked microsatellites. One marker was not polymorphic within either family. Several markers suggested exclusion (Z < ,2.0) at distances of 7.5,33 cM. Exclusion analyses suggested a possible location for orange a 14 cM region near Xcen. Recombination distances of markers in the segregating feline pedigrees were reduced as compared with the feline interspecies backcross family. Thus, the presented pedigrees may be useful as reference families for the domestic cat because more accurate recombination rates for domestic cats can be determined. [source]


Geophysical Investigation at the Falling Creek Ironworks, an Early Industrial Site in Virginia

ARCHAEOLOGICAL PROSPECTION, Issue 4 2001
Geoffrey Jones
Abstract A geophysical investigation was conducted at the site of the Falling Creek Ironworks (1619,1622), the first iron production facility in North America. Electrical resistance and magnetic field gradient surveys were conducted over the site of the seventeenth century ironworks. Additionally, ground-penetrating radar was used to investigate areas under an existing roadway. Linear and rectangular anomalies that appear in the resistance data may be caused by architectural features, possibly shops or domestic structures associated with the ironworks. Several low-amplitude magnetic anomalies that appear in the data appear to be cultural in origin, and may be caused by features associated with the ironworks. A number of high-amplitude magnetic anomalies appear in the magnetic field gradient data that are thought to be associated with iron production, including extensive slag deposits and the possible location of the blast furnace. Ground-penetrating radar data shows an anomalous reflection in the vicinity of the suspected blast furnace, which is partially beneath the modern roadway. Copyright © 2001 John Wiley & Sons, Ltd. [source]


Structural Investigation of a High-Affinity MnII Binding Site in the Hammerhead Ribozyme by EPR Spectroscopy and DFT Calculations.

CHEMBIOCHEM, Issue 10 2003
Effects of Neomycin B on Metal-Ion Binding
Abstract Electron paramagnetic resonance spectroscopy and density functional theory methods were used to study the structure of a single, high-affinity MnIIbinding site in the hammerhead ribozyme. This binding site exhibits a dissociation constant Kdof 4.4 ,M in buffer solutions containing 1,M NaCl, as shown by titrations monitored by continuous wave (cw) EPR. A combination of electron spin echo envelope modulation (ESEEM) and hyperfine sublevel correlation (HYSCORE) experiments revealed that the paramagnetic manganese(II) ion in this binding site is coupled to a single nitrogen atom with a quadrupole coupling constant,of 0.7 MHz, an asymmetry parameter,of 0.4, and an isotropic hyperfine coupling constant of Aiso(14N)=2.3 MHz. All three EPR parameters are sensitive to the arrangement of the MnIIligand sphere and can therefore be used to determine the structure of the binding site. A possible location for this binding site may be at the G10.1, A9 site found to be occupied by MnIIin crystals (MacKay et al., Nature 1994, 372, 68 and Scott et al., Science 1996, 274, 2065). To determine whether the structure of the binding site is the same in frozen solution, we performed DFT calculations for the EPR parameters, based on the structure of the MnIIsite in the crystal. Computations with the BHPW91 density function in combination with a 9s7p4d basis set for the manganese(II) center and the Iglo-II basis set for all other atoms yielded values of,(14N)=+0.80 MHz, ,=0.324, and Aiso(14N)=+2.7 MHz, in excellent agreement with the experimentally obtained EPR parameters, which suggests that the binding site found in the crystal and in frozen solution are the same. In addition, we demonstrated by EPR that MnIIis released from this site upon binding of the aminoglycoside antibiotic neomycin B (Kd=1.2 ,M) to the hammerhead ribozyme. Neomycin B has previously been shown to inhibit the catalytic activity of this ribozyme (Uhlenbeck et al., Biochemistry 1995, 34, 11,186). [source]