Sequence characterisation and expression of homeobox HOX A7 in the multi-potential erythroleukaemic cell line TF-1

Homeobox gene expression was examined in the erythroleukaemic cell line TF-1. Expression of a number of HOX A, B and C genes, including HOX A7 was detected. Expression of this gene has not previously been reported in erythroleukaemic cell lines. A 2.1 kb full length cDNA of the HOX A7 gene was cloned. The predicted amino acid sequence C-terminal to the homeodomain consists of an alanine-rich region and a strongly negatively charged domain consisting entirely of aspartic and glutamic acid residues.

Measurement and modelling of perceived slant in surfaces represented by freely viewed line drawings

Simple pictures under everyday viewing conditions evoke impressions of surfaces oriented in depth. These impressions have been studied by measuring the slants of perceived surfaces, with probes (rotating arrowheads) designed to respect the distinctive character of depicted scenes. Converging arguments indicated that the perceived orientation of the probes was near theoretical values. A series of experiments showed that subjects formed well-defined impressions of depicted surface orientation. The literature suggests that perceived objects might be flattened', but that was not the general rule. Instead, both mean slant and uncertainty fitted models in which slant estimates are derived in a relatively straightforward way from local relations in the picture. Simplifying pictures tended to make orientation estimates less certain, particularly away from the natural anchor points (vertical and horizontal). The shape of the object affected all aspects of the observed-object/percept relationship. Individual differences were large, and suggest that different individuals used different relationships as a basis for their estimates. Overall, data suggest that everyday picture perception is strongly selective and weakly integrative. In particular, depicted slant is estimated by finding a picture feature which will be strongly related to it if the object contains a particular regularity, not by additive integration of evidence from multiple directly and indirectly relevant sources.

Variation among nonclinical subjects on a line-bisection task

Absence of leftward bias in a line bisection task is often used as a clinical hemispheric indicator, but the effect is not uniform in a normal population. Sex, handedness, and strategy variables affect the strength and direction of any bias.

FROM LINE-DRAWINGS TO IMPRESSIONS OF 3D OBJECTS - DEVELOPING A MODEL TO ACCOUNT FOR THE SHAPES THAT PEOPLE SEE

The interpretations people attach to line drawings reflect shape-related processes in human vision. Their divergences from expectations embodied in related machine vision traditions are summarized, and used to suggest how human vision decomposes the task of interpretation. A model called IO implements this idea. It first identifies geometrically regular, local fragments. Initial decisions fix edge orientations, and this information constrains decisions about other properties. Relations between fragments are explored, beginning with weak consistency checks and moving to fuller ones. IO's output captures multiple distinctive characteristics of human performance, and it suggests steady progress towards understanding shape-related visual processes is possible.

Interaction strengths in food webs: issues and opportunities

1. Recent efforts to understand how the patterning of interaction strength affects both structure and dynamics in food webs have highlighted several obstacles to productive synthesis. Issues arise with respect to goals and driving questions, methods and approaches, and placing results in the context of broader ecological theory.

Chemical and mechanical stability of sodium sulfate activated slag after exposure to elevated temperature

The chemical and mechanical stability of slag activated with two different concentrations of sodium sulfate (Na₂SO₄) after exposure to elevated temperatures ranging from 200 to 800 °C with an increment of 200 °C has been examined. Compressive strengths and pH of the hardened pastes before and after the exposure were determined. The various decomposition phases formed were identified using X-ray diffraction, thermogravimetric analysis and scanning electron microscopy. The results indicated that Na₂SO₄ activated slag has a better resistance to the degradation caused by exposure to elevated temperature up to 600 °C than Portland cement system as its relative strengths are superior. The finer slag and higher Na₂SO₄ concentration gave better temperature resistance. Whilst the pH of the hardened pastes decreased with an increase in temperature, it still maintained a sufficiently high pH for the protection of reinforcing bar against corrosion.

Detection of Voigt Spectral Line Profiles of Hydrogen Radio Recombination Lines toward Sagittarius B2(N)

We report the detection of Voigt spectral line profiles of radio recombination lines (RRLs) toward Sagittarius B2(N) with the 100 m Green Bank Telescope (GBT). At radio wavelengths, astronomical spectra are highly populated with RRLs, which serve as ideal probes of the physical conditions in molecular cloud complexes. An analysis of the Hn alpha lines presented herein shows that RRLs of higher principal quantum number (n > 90) are generally divergent from their expected Gaussian profiles and, moreover, are well described by their respective Voigt profiles. This is in agreement with the theory that spectral lines experience pressure broadening as a result of electron collisions at lower radio frequencies. Given the inherent technical difficulties regarding the detection and profiling of true RRL wing spans and shapes, it is crucial that the observing instrumentation produce flat baselines as well as high-sensitivity, high-resolution data. The GBT has demonstrated its capabilities regarding all of these aspects, and we believe that future observations of RRL emission via the GBT will be crucial toward advancing our knowledge of the larger-scale extended structures of ionized gas in the interstellar medium (ISM).

Porcine Circovirus Type 2 Morphogenesis in a Clone Derived from the L35 Lymphoblastoid Cell Line

Porcine circovirus type 2 (PCV2) is the essential infectious agent of post-weaning multisystemic wasting syndrome (PMWS), one of the most important diseases of swine. Although several studies have described different biological properties of the virus, some aspects of its replication cycle, including ultrastructural alterations, remain unknown. The aim of the present study was to describe for the first time a complete morphogenesis study of PCV2 in a clone of the lymphoblastoid L35 cell line at the ultrastructural level using electron microscopy techniques. Cells were infected with PCV2 at a multiplicity of infection of 10 and examined at 0, 6, 12, 24, 48, 60 and 72 h post-infection. PCV2 was internalized by endocytosis, after which the virus aggregated in intracytoplasmic inclusion bodies (ICIs). Subsequently, PCV2 was closely associated with mitochondria, completing a first cytoplasmic phase. The virus entered the nucleus for replication and virus assembly and encapsidation occurred with the participation of the nuclear membrane. Immature virions left the nucleus and formed ICIs in a second cytoplasmic phase. The results suggest that at the end of the replication cycle (between 24 and 48 h), PCV2 was released either by budding of mature virion clusters or by lysis of apoptotic or dead cells. In conclusion, the L35-derived clone represents a suitable in-vitro model for PCV2 morphogenesis studies and characterization of the PCV2 replication cycle. (C) 2010 Elsevier Ltd. All rights reserved.

Collisions Strengths and Effective Collision Strengths for transitions within the ground state configuration of S III

We have carried out a 29-state R-matrix calculation in order to calculate collision strengths and effective collision strengths for the electron impact excitation of S III. The recently developed parallel RMATRX II suite of codes have been used, which perform the calculation in intermediate coupling. Collision strengths have been generated over an electron energy range of 0-12 Ryd, and effective collision strength data have been calculated from these at electron temperatures in the range 1000-100,000 K. Results are here presented for the fine-structure transitions between the ground-state configurations of 3s(2)3p(2) P-3(0,1,2), D-1(2), and S-1(0), and the values given resolve a discrepancy between two previous R-matrix calculations.

Electron-impact excitation of Sc II: collision strengths and effective collision strengths for fine-structure transitions.

Accurate fine-structure atomic data for the Fe-peak elements are essential for interpreting astronomical spectra. There is a severe paucity of data available for Sc II, highlighted by the fact that no collision strengths are readily available for this ion. We present electron-impact excitation collision strengths and Maxwellian averaged effective collision strengths for Sc II. The collision strengths were calculated for all 3916 transitions amongst 89 jj levels (arising from the 3d4s, 3d2, 4s2, 3d4p, 4s4p, 3d5s, 3d4d, 3d5p, 4p2 and 3d4f configurations), resulting in a 944 coupled channel problem. The R-matrix package RMATRXII was utilized, along with the transformation code FINE and the external region code PSTGF, to calculate the collision strengths for a range of incident electron energies in the 0 to 8.3 Rydberg region. Maxwellian averaged effective collision strengths were then produced for 27 temperatures lying within the astrophysically significant range of 30 to 105 K.
The collision strengths and effective collision strengths were produced for two different target models. The purpose was to systematically examine the effect of including open 3p correlation terms into the configuration interaction expansion for the wavefunction. The first model consisted of all 36 CI terms that could be generated with the 3p core closed. The second model incorporated an additional six configurations which allowed for single-electron excitations from within the 3p core. Comparisons are made between the two models and the results of Bautista et al., obtained by private communication. It is concluded that the first model produced the most reliable set of collision and effective collision strengths for use in astrophysical and plasma applications.