2,287 research outputs found

    Ground and excited states of Li^-, Be^- through a density-based approach

    Full text link
    Density functional calculations are performed for ground [He]2s2^2 1^1Se^e, and three metastable bound excited states, 1s2s2p2^2 5^5Pe^e, 1s2p3^3 5^5So^o, 1s2s2p3p 5^5Pe^e of Li^- and [He]2s2p2^2 4^4Pe^e, [He]2p3^3 4^4So^o, 1s2s2p3^3 6^6So^o of Be^- each. The work-function-based exchange potential is used, while the correlation effects are included by employing the Lee-Yang-Parr potential. The relevant nonrelativistic KS equation is solved by means of a generalized pseudospectral discretization scheme offering nonuniform and optimal spatial grid. Computed total energies, radial densities, selected density moments, as well as two transition wavelengths (1s2s2p2^2 5^5Pe^e \to1s2p3^3 5^5So^o of Li^-, [He]2s2p2^2 4^4Pe^e \to [He]2p3^3 4^4So^o of Be^-) show reasonably good agreement with the available theoretical and experimental data. The term energies show an absolute deviation of 0.007--0.171% with the largest deviation being observed for the even-parity 5^5P state of Li^-. The transition wavelengths of Li^-, Be^- are calculated within 0.891 and 0.438% of the experimental values. This offers a simple practical route towards accurate reliable calculation of excited states of anions within density functional theory.Comment: 12 pages, 35 ref

    The time delay of the quadruple quasar RX J0911.4+0551

    Full text link
    We present optical lightcurves of the gravitationally lensed components A (=A1+A2+A3) and B of the quadruple quasar RX J0911.4+0551 (z = 2.80). The observations were primarily obtained at the Nordic Optical Telescope between 1997 March and 2001 April and consist of 74 I-band data points for each component. The data allow the measurement of a time delay of 146 +- 8 days (2 sigma) between A and B, with B as the leading component. This value is significantly shorter than that predicted from simple models and indicates a very large external shear. Mass models including the main lens galaxy and the surrounding massive cluster of galaxies at z = 0.77, responsible for the external shear, yield H_0 = 71 +- 4 (random, 2 sigma) +- 8 (systematic) km/s/Mpc. The systematic model uncertainty is governed by the surface-mass density (convergence) at the location of the multiple images.Comment: 12 pages, 3 figures, ApJL, in press (June 20, 2002

    Climate-based Daylight Performance: Balancing Visual and Non-visual Aspects of Light Input

    Get PDF
    This study uses a domestic dwelling as the setting to investigate and explore the applicability of daylighting metrics for residential buildings, including the formulation of metrics for nonvisual effects. The simulation approach used to generate the performance data from which the metrics are derived is called climate-based daylight modelling (CBDM). This approach delivers predictions of various luminous quantities using sun and sky conditions that are derived from standardised annual meteorological datasets. Although there are uncertainties regarding the precise calibration, there is now sufficient empirical data to parameterise models that also simulate the non-visual aspects of daylight, e.g. for circadian entrainment and a general sense of "alertness". For these non-visual aspects, vertical illuminance at the eye was predicted using a modified climate-based daylight modelling approach. In the paper, we consider what relation there might be between the three aspects of daylight provision and if these relations appear to be complementary or conflicting in nature: for task; to reduce electric lighting usage; and, for non-visual effects. The implications for future building guidelines for daylighting are also discussed

    A framework for predicting the non-visual effects of daylight – Part II: The simulation model

    Get PDF
    This paper describes a climate-based simulation framework devised to investigate the potential for the non-visual effects of daylight in buildings. It is part 2 of a study where the first paper focused on the formulation of the photobiological underpinnings of a threshold-based model configured for lighting simulation from the perspective of the human nonvisual system (e.g. circadian response). This threshold-based model employs a static dose-response curve and instantaneous exposure of daylight at the eye to estimate the magnitude of the non-visual effect as a first step towards a simulation framework that would establish a link between light exposure at the eye in an architectural context and expected effects on the non-visual system. In addition to being highly sensitive to the timing and duration of light exposure, the non-visual systems fundamentally differs from the visual system in its action spectrum. The photosensitive retinal ganglion cells that communicate light exposure to the brain is known to be shifted to the blue with respect to the photopic sensitivity curve. Thus the spectral character of daylight also becomes a sensitive factor in the magnitude of the predicted non-visual effect. This is accounted for in the model by approximating `yellow' sunlight, `grey' skylight and `blue' skylight to three distinct CIE illuminant types, and then tracking their `circadian-lux' weighted contributions in the summation of daylight received at the eye. A means to `condense' nonvisual effects into a synthesised graphical format for the year, split by periods of the day, is described in terms of how such a format could inform design decisions. The sensitivity of the simulation model's predictions to prevailing climate and building orientation is demonstrated by comparing results from eight European locations

    Daylighting, Artificial Lighting and Non-Visual Effects Study for a Residential Building

    Get PDF
    The study uses a domestic dwelling as the setting to investigate and explore the applicability of daylighting metrics for residential buildings. The metrics address daylight provision for task and electric lighting usage. In addition to these it also investigates the formulation of preliminary metrics to evaluating the potential for non-visual effects. The setting, a residential building with and without skylights, was evaluated for all 32 combinations of eight European climates and four building orientations covering the cities of Hamburg, London, Madrid, Moscow, Ostersund, Paris, Rome and Warsaw. The evaluation is based on a real life renovation case in which new skylights have been added to the kitchen, living room, large and small bathrooms and staircase. This section summarises the findings based on 64 unique sets of climate-based daylight simulation (32 combinations x 2 design variants) in which three different aspects of daylight are evaluated: daylighting performance, energy savings for lighting and non-visual effects

    Inhibition of Nonsense-Mediated mRNA Decay by Antisense Morpholino Oligonucleotides Restores Functional Expression of hERG Nonsense and Frameshift Mutations in Long-QT Syndrome

    Full text link
    Mutations in the human ether-a-go-go-related gene (hERG) cause long-QT syndrome type 2 (LQT2). We previously described a homozygous LQT2 nonsense mutation Q1070X in which the mutant mRNA is degraded by nonsense-mediated mRNA decay (NMD) leading to a severe clinical phenotype. The degradation of the Q1070X transcript precludes the expression of truncated but functional mutant channels. In the present study, we tested the hypothesis that inhibition of NMD can restore functional expression of LQT2 mutations that are targeted by NMD. We showed that inhibition of NMD by RNA interference-mediated knockdown of UPF1 increased Q1070X mutant channel protein expression and hERG current amplitude. More importantly, we found that specific inhibition of downstream intron splicing by antisense morpholino oligonucleotides prevented NMD of the Q1070X mutant mRNA and restored the expression of functional Q1070X mutant channels. The restoration of functional expression by antisense morpholino oligonucleotides was also observed in LQT2 frameshift mutations. Our findings suggest that inhibition of NMD by antisense morpholino oligonucleotides may be a potential therapeutic approach for some LQT2 patients carrying nonsense and frameshift mutations

    Prognostic Impacts of Hypoxic Markers in Soft Tissue Sarcoma

    Get PDF
    Background. We aimed to explore the prognostic impact of the hypoxia-induced factors (HIFαs) 1 and 2, the metabolic HIF-regulated glucose transporter GLUT-1, and carbonic anhydrase IX (CAIX) in non-gastrointestinal stromal tumor soft tissue sarcomas (non-GIST STS). Methods. Duplicate cores with viable tumor tissue from 206 patients with non-GIST STS were obtained and tissue microarrays were constructed. Immunohistochemistry (IHC) was used to evaluate expression of hypoxic markers. Results. In univariate analyses, GLUT-1 (P < 0.001) and HIF-2α (P = 0.032) expression correlated significantly with a poor disease-specific survival (DSS). In the multivariate analysis, however, only high expression of GLUT-1 (HR 1.7, CI 95% 1.1–2.7, P = 0.021) was a significant independent prognostic indicator of poor DSS. Conclusion. GLUT-1 is a significant independent negative prognostic factor in non-GIST STS

    SIP1/ZEB2 induces EMT by repressing genes of different epithelial cell–cell junctions

    Get PDF
    SIP1/ZEB2 is a member of the δEF-1 family of two-handed zinc finger nuclear factors. The expression of these transcription factors is associated with epithelial mesenchymal transitions (EMT) during development. SIP1 is also expressed in some breast cancer cell lines and was detected in intestinal gastric carcinomas, where its expression is inversely correlated with that of E-cadherin. Here, we show that expression of SIP1 in human epithelial cells results in a clear morphological change from an epithelial to a mesenchymal phenotype. Induction of this epithelial dedifferentiation was accompanied by repression of several cell junctional proteins, with concomitant repression of their mRNA levels. Besides E-cadherin, other genes coding for crucial proteins of tight junctions, desmosomes and gap junctions were found to be transcriptionally regulated by the transcriptional repressor SIP1. Moreover, study of the promoter regions of selected genes by luciferase reporter assays and chromatin immunoprecipitation shows that repression is directly mediated by SIP1. These data indicate that, during epithelial dedifferentiation, SIP1 represses in a coordinated manner the transcription of genes coding for junctional proteins contributing to the dedifferentiated state; this repression occurs by a general mechanism mediated by Smad Interacting Protein 1 (SIP1)-binding sites
    corecore