Children’s respiratory health and daily particulate levels in ten non-urban communities

We conducted a study to assess the association between the acute respiratory health of children and the levels of particulates in communities near and away from active opencast coal mines. The study enrolled children aged 1–11 years from the general population of five socioeconomically matched pairs of nonurban communities in northern England. Diaries of respiratory events were collected for 1405 children, and information was collected on the consultations of 2442 children with family/general practitioners over the 6-week study periods during 1996–1997, with concurrent monitoring of particulate levels. The associations found between daily PM10 levels and respiratory symptoms were frequently small and positive and sometimes varied between communities. The magnitude of these associations were in line with those from previous studies, even though daily particulate levels were low, and the children were drawn from the general population, rather than from the population with respiratory problems. The associations among asthma reliever use, consultations with general practitioners, and daily particulate levels were of a similar strength but estimated less precisely. The strength of association between all respiratory health measures and particulate levels was similar in communities near and away from opencast coal mining sites.

A scheme for efficient quantum computation wtih linear optics

Quantum computers promise to increase greatly the efficiency of solving problems such as factoring large integers, combinatorial optimization and quantum physics simulation. One of the greatest challenges now is to implement the basic quantum-computational elements in a physical system and to demonstrate that they can be reliably and scalably controlled. One of the earliest proposals for quantum computation is based on implementing a quantum bit with two optical modes containing one photon. The proposal is appealing because of the ease with which photon interference can be observed. Until now, it suffered from the requirement for non-linear couplings between optical modes containing few photons. Here we show that efficient quantum computation is possible using only beam splitters, phase shifters, single photon sources and photo-detectors. Our methods exploit feedback from photo-detectors and are robust against errors from photon loss and detector inefficiency. The basic elements are accessible to experimental investigation with current technology.

Exact solution of the A(n-1)((1)) trigonometric vertex model with non-diagonal open boundaries

The A(n-1)((1)) trigonometric vertex model with generic non-diagonal boundaries is studied. The double-row transfer matrix of the model is diagonalized by algebraic Bethe ansatz method in terms of the intertwiner and the corresponding face-vertex relation. The eigenvalues and the corresponding Bethe ansatz equations are obtained.

Non-Equilibrium Reaction Rates in the Macroscopic Chemistry Method for DSMC Calculations

The Direct Simulation Monte Carlo (DSMC) method is used to simulate the flow of rarefied gases. In the Macroscopic Chemistry Method (MCM) for DSMC, chemical reaction rates calculated from local macroscopic flow properties are enforced in each cell. Unlike the standard total collision energy (TCE) chemistry model for DSMC, the new method is not restricted to an Arrhenius form of the reaction rate coefficient, nor is it restricted to a collision cross-section which yields a simple power-law viscosity. For reaction rates of interest in aerospace applications, chemically reacting collisions are generally infrequent events and, as such, local equilibrium conditions are established before a significant number of chemical reactions occur. Hence, the reaction rates which have been used in MCM have been calculated from the reaction rate data which are expected to be correct only for conditions of thermal equilibrium. Here we consider artificially high reaction rates so that the fraction of reacting collisions is not small and propose a simple method of estimating the rates of chemical reactions which can be used in the Macroscopic Chemistry Method in both equilibrium and non-equilibrium conditions. Two tests are presented: (1) The dissociation rates under conditions of thermal non-equilibrium are determined from a zero-dimensional Monte-Carlo sampling procedure which simulates ‘intra-modal’ non-equilibrium; that is, equilibrium distributions in each of the translational, rotational and vibrational modes but with different temperatures for each mode; (2) The 2-D hypersonic flow of molecular oxygen over a vertical plate at Mach 30 is calculated. In both cases the new method produces results in close agreement with those given by the standard TCE model in the same highly nonequilibrium conditions. We conclude that the general method of estimating the non-equilibrium reaction rate is a simple means by which information contained within non-equilibrium distribution functions predicted by the DSMC method can be included in the Macroscopic Chemistry Method.

Molecular cocrystals of carboxylic acids. XXVII - An investigation into the use of triphenylphosphine oxide cocrystals for non-linear optics: the crystal structure of the adduct of triphenylphosphine oxide with N-methylpyrrole-2-carboxylic acid

Four adducts of triphenylphosphine oxide with aromatic carboxylic acids have been synthesized and tested for second-order non-linear optical properties. These were with N-methylpyrrole-2-carboxylic acid (I), indole-2-carboxylic acid (2), 3-dimethylaminobenzoic acid (3), and thiophen-2-carboxylic acid (4). Compound (1) produced clear, colourless crystals (space group P2(1)2(1)2(1) With a 9.892(1), b 14.033(1), c 15.305(1) Angstrom, Z 4) which allowed the structure to be determined by X-ray diffraction.

Inhibition of phenotype modulation, growth, and migration of vascular smooth muscle cells by a guanosine-rich 30-mer phosphorothioate oligodeoxynucleotide

The testing of a 30-mer dG-rich phosphorothioate oligodeoxynucleotide (LG4PS) for effects on the behaviour of vascular smooth muscle cells (VSMC) in vitro and in vivo is described. LG4PS at 0.3 mu M inhibited significantly the phenotype modulation of freshly isolated rabbit VSMC, and cell outgrowth from pig aortic explants was inhibited similar to 80% by 5 mu M LG4PS. The growth of proliferating rabbit and pig VSMC was inhibited similar to 70% by 0.3 mu M and 5 mu M LG4PS, respectively. Though less marked, the antiproliferative effects of LG4PS on human VSMC were comparable to those obtained with heparin. The cytotoxic effects of LG4PS on VSMC in vitro were low. Despite these promising results, adventitial application of 2-200 nmol LG4PS in pluronic gel failed to reduce vascular hyperplasia in balloon-injured rabbit carotid arteries, and the highest dose caused extensive mortality. (C) 1997 Academic Press Limited.

Seven retinal specializations in the tubular eye of the deep-sea pearleye, Scopelarchus michaelsarsi: A case study in visual optimization

The deep-sea pearleye, Scopelarchus michaelsarsi (Scopelarchidae) is a mesopelagic teleost with asymmetric or tubular eyes. The main retina subtends a large dorsal binocular field, while the accessory retina subtends a restricted monocular field of lateral visual space. Ocular specializations to increase the lateral visual field include an oblique pupil and a corneal lens pad. A detailed morphological and topographic study of the photoreceptors and retinal ganglion cells reveals seven specializations: a centronasal region of the main retina with ungrouped rod-like photoreceptors overlying a retinal tapetum; a region of high ganglion cell density (area centralis of 56.1x10(3) cells per mm(2)) in the centrolateral region of the main retina; a centrotemporal region of the main retina with grouped rod-like photoreceptors; a region (area giganto cellularis) of large (32.2+/-5.6 mu m(2)), alpha-like ganglion cells arranged in a regular array (nearest neighbour distance 53.5+/-9.3 mu m with a conformity ratio of 5.8) in the temporal main retina; an accessory retina with grouped rod-like photoreceptors; a nasotemporal band of a mixture of rod-and cone-like photoreceptors restricted to the ventral accessory retina; and a retinal diverticulum comprised of a ventral region of differentiated accessory retina located medial to the optic nerve head. Retrograde labelling from the optic nerve with DiI shows that approximately 14% of the cells in the ganglion cell layer of the main retina are displaced amacrine cells at 1.5 mm eccentricity. Cryosectioning of the tubular eye confirms Matthiessen's ratio (2.59), and calculations of the spatial resolving power suggests that the function of the area centralis (7.4 cycles per degree/8.1 minutes of are) and the cohort of temporal alpha-like ganglion cells (0.85 cycles per degree/70.6 minutes of are) in the main retina may be different. Low summation ratios in these various retinal zones suggests that each zone may mediate distinct visual tasks in a certain region of the visual field by optimizing sensitivity and/or resolving power.

Changes in three-dimensional architecture of microfilaments in cultured vascular smooth muscle cells during phenotypic modulation

To investigate changes in the three-dimensional microfilament architecture of vascular smooth muscle cells (SMC) during the process of phenotypic modulation, rabbit aortic SMCs cultured under different conditions and at different time points were either labelled with fluorescein-conjugated probes to cytoskeletal and contractile proteins for observation by confocal laser scanning microscopy, or extracted with Triton X-100 for scanning electron microscopy. Densely seeded SMCs in primary culture, which maintain a contractile phenotype, display prominent linear myofilament bundles (stress fibres) that are present throughout the cytoplasm with alpha-actin filaments predominant in the central part and beta-actin filaments in the periphery of the cell. Intermediate filaments form a meshed network interconnecting the stress fibres and linking directly to the nucleus. Moderately and sparsely seeded SMCs, which modulate toward the synthetic phenotype during the first 5 days of culture, undergo a gradual redistribution of intermediate filaments from the perinuclear region toward the peripheral cytoplasm and a partial disassembly of stress fibres in the central part of the upper cortex of the cytoplasm, with an obvious decrease in alpha-actin and myosin staining. These changes are reversed in moderately seeded SMCs by day 8 of culture when they have reached confluence. The results reveal two changes in microfilament architecture in SMCs as they undergo a change in phenotype: the redistribution of intermediate filaments probably due to an increase in synthetic organelles in the perinuclear area, and the partial disassembly of stress fibres which may reflect a degradation of contractile components.

Arterial heparan sulfate proteoglycans inhibit vascular smooth muscle cell proliferation and phenotype change in vitro and neointimal formation in vivo

Purpose: The aim of this study was to determine whether heparan sulfate proteoglycans (HSPGs) from the normal arterial wall inhibit neointimal formation after injury in vivo and smooth muscle cell (SMC) phenotype change and proliferation in vitro. Methods: Arterial HSPGs were extracted from rabbit aortae and separated by anion-exchange chromatography. The effect of HSPGs, applied in a periadventitial gel, on neointimal formation was assessed 14 days after balloon catheter injury of rabbit carotid arteries. Their effect on SMC phenotype and proliferation was measured by point-counting morphometry of the cytoplasmic volume fraction of myofilaments (Vvmyo) and H-3-thymidine incorporation in SMCs in culture. Results: Arterial HSPGs (680 mu g) reduced neointimal formation by 35% at 14 days after injury (P =.029), whereas 2000 mu g of the low-molecular-weight heparin Enoxaparin was ineffective. HSPGs at 34 mu g/mL maintained subconfluent primary cultured SMCs with the same high Vvmyo (52.1% +/- 13.8%) after 5 days in culture as did cells freshly isolated from the arterial wall (52.1% +/- 15.1%). In contrast, 100 mu g/mL Enoxaparin was ineffective in preventing phenotypic change over this time period (Vvmyo 38.9% +/- 14.6%, controls 35.9% +/- 12.8%). HSPGs also inhibited 3H-thymidine incorporation into primary cultured SMCs with an ID50 value of 0.4 mu g/mL compared with a value of 14 mu g/ml; for Enoxaparin (P

Comparative labor market performance of visaed and non-visaed migrants: Pacific islanders in Sydney

Using survey data for Tongan and Samoan migrants in Sydney the effects of visa restrictions on labor market performance of migrants are assessed. Univariate analysis suggests a positive association between unemployment and the unrestricted entry of Samoan step-migrants from New Zealand. A probit model of the determinants of unemployment is estimated with controls for human capital and demographic variables. While human capital endowments are important, visa restrictions do not have a significant effect on either group's employability. Implications for policy are discussed highlighting the complementarities between host country immigration policies and foreign aid programs.

Effect of estrogen on vascular smooth muscle cells is dependent upon cellular phenotype

To investigate the growth-regulating action of estrogen on vascular smooth muscle cells (SMC), effects of beta-17-estradiol (beta-E-2) on phenotypic modulation and proliferation of rabbit aortic SMC were observed in vitro. At 10(-8) M, beta-E-2 significantly slowed the decrease in volume fraction of myofilaments (V(v)myo) of freshly dispersed SMCs in primary culture, indicating an inhibitory effect of beta-E-2 On spontaneous phenotypic modulation of SMC from a contractile to a synthetic phenotype. Freshly dispersed SMCs treated with beta-E-2 also had a relatively longer quiescent phase than control cells before intense proliferation occurred. This was in contrast to SMCs in passage 2-3 (synthetic state), where beta-E-2-treated cells replicated significantly faster than untreated cells. beta-E-2 also markedly enhanced the serum-induced DNA synthesis of synthetic SMCs in a concentration-dependent manner within physiological range (10(-10) to 10-8 M). These findings indicate that the growth-regulating effect of estrogen on vascular SMC is dependent on the cell's phenotypic stare. It delays the cell cycle re-entry of the contractile SMCs by retarding their phenotypic modulation however, once cells have modulated to the synthetic phenotype, it promotes their replication. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.

Analysis of small signal stability margins using genetic optimization

Power system small signal stability analysis aims to explore different small signal stability conditions and controls, namely: (1) exploring the power system security domains and boundaries in the space of power system parameters of interest, including load flow feasibility, saddle node and Hopf bifurcation ones; (2) finding the maximum and minimum damping conditions; and (3) determining control actions to provide and increase small signal stability. These problems are presented in this paper as different modifications of a general optimization to a minimum/maximum, depending on the initial guesses of variables and numerical methods used. In the considered problems, all the extreme points are of interest. Additionally, there are difficulties with finding the derivatives of the objective functions with respect to parameters. Numerical computations of derivatives in traditional optimization procedures are time consuming. In this paper, we propose a new black-box genetic optimization technique for comprehensive small signal stability analysis, which can effectively cope with highly nonlinear objective functions with multiple minima and maxima, and derivatives that can not be expressed analytically. The optimization result can then be used to provide such important information such as system optimal control decision making, assessment of the maximum network's transmission capacity, etc. (C) 1998 Elsevier Science S.A. All rights reserved.

Phosphorylation of the C-terminal sites of human p53 reduces non-sequence-specific DNA binding as modeled with synthetic peptides

Phosphorylation of the tumor suppressor p53 is generally thought to modify the properties of the protein in four of its five independent domains. We used synthetic peptides to directly study the effects of phosphorylation on the non-sequence-specific DNA binding and conformation of the C-terminal, basic domain. The peptides corresponded to amino acids 361-393 and were either nonphosphorylated or phosphorylated at the protein kinase C (PKC) site, Ser378, or the casein kinase II (CKII) site, Ser392, or bis-phosphorylated on both the PKC and the CKII sites. A fluorescence polarization analysis revealed that either the recombinant p53 protein or the synthetic peptides bound to two unrelated target DNA fragments. Phosphorylation of the peptide at the PKC or the CKII sites clearly decreased DNA binding, and addition of a second phosphate group almost completely abolished binding. Circular dichroism spectroscopy showed that the peptides assumed identical unordered structures in aqueous solutions. The unmodified peptide, unlike the Ser378 phosphorylated peptide, changed conformation in the presence of DNA. The inherent ability of the peptides to form an alpha-helix could be detected when circular dichroism and nuclear magnetic resonance spectra were: taken in trifluoroethanol-water mixtures. A single or double phosphorylation destabilized the helix around the phosphorylated Ser378 residue but stabilized the helix downstream in the sequence.