161 research outputs found

    Federal Employee is Entitled to Trial De Novo on Employment Discrimination Claim and Not Merely Judicial Review of Agency Record. Hackley v. Roudebush, 520 F.2d 108 (D.C. Cir. 1975).

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    Ralph Hackley, an African American, was employed as an investigator within the Veteran Administration\u27s Investigation and Security Service Division. He had served for one year at the GS-12 level when he was denied promotion. Hackley complained that this denial was based solely upon his race. The charge was investigated and he was afforded a hearing before a complaints examiner, who ruled that there had been no discrimination. This finding was adopted by the Veteran\u27s Administration. Upon appeal, the Board of Appeals and Review of the Civil Service Commission affirmed. Having thus exhausted his administrative remedies, plaintiff commenced a civil action in the District Court for the District of Columbia pursuant to section 717(c) of the Equal Employment Opportunity Act of 1972 (EEOA). He sought injunctive relief, retroactive promotion, and back pay, plus a declaratory judgment to the effect that he was to be free from discrimination. The district court, in Hackley v. Johnson (Hackley 1), granted the government\u27s motion for summary judgment, holding that it only had jurisdiction to consider whether Hackley had been afforded administrative due process before the Civil Service Commission and that he had, in fact, received due process during the administrative hearing. In Hackley v. Roudebush (Hackley II), the Court of Appeals for the District of Columbia Circuit reversed, remanding Hackley\u27s claim of discrimination for trial, concluding, inter alia, that section 717(c)\u27s grant of a private right of action requires the district court to conduct a trial de novo in civil actions filed under the section. In so ruling, the court fell into line with several other jurisdictions which had held that the vindication of a federal employee\u27s rights under EEOA required more than mere review of the administrative record

    The Atacama Cosmology Telescope: Two-Season ACTPol Spectra and Parameters

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    We present the temperature and polarization angular power spectra measured by the Atacama Cosmology Telescope Polarimeter (ACTPol). We analyze night-time data collected during 2013-14 using two detector arrays at 149 GHz, from 548 deg2^2 of sky on the celestial equator. We use these spectra, and the spectra measured with the MBAC camera on ACT from 2008-10, in combination with Planck and WMAP data to estimate cosmological parameters from the temperature, polarization, and temperature-polarization cross-correlations. We find the new ACTPol data to be consistent with the LCDM model. The ACTPol temperature-polarization cross-spectrum now provides stronger constraints on multiple parameters than the ACTPol temperature spectrum, including the baryon density, the acoustic peak angular scale, and the derived Hubble constant. Adding the new data to planck temperature data tightens the limits on damping tail parameters, for example reducing the joint uncertainty on the number of neutrino species and the primordial helium fraction by 20%.Comment: 23 pages, 25 figure

    Search for Kaluza-Klein Graviton Emission in ppˉp\bar{p} Collisions at s=1.8\sqrt{s}=1.8 TeV using the Missing Energy Signature

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    We report on a search for direct Kaluza-Klein graviton production in a data sample of 84 pb1{pb}^{-1} of \ppb collisions at s\sqrt{s} = 1.8 TeV, recorded by the Collider Detector at Fermilab. We investigate the final state of large missing transverse energy and one or two high energy jets. We compare the data with the predictions from a 3+1+n3+1+n-dimensional Kaluza-Klein scenario in which gravity becomes strong at the TeV scale. At 95% confidence level (C.L.) for nn=2, 4, and 6 we exclude an effective Planck scale below 1.0, 0.77, and 0.71 TeV, respectively.Comment: Submitted to PRL, 7 pages 4 figures/Revision includes 5 figure

    Measurement of the average time-integrated mixing probability of b-flavored hadrons produced at the Tevatron

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    We have measured the number of like-sign (LS) and opposite-sign (OS) lepton pairs arising from double semileptonic decays of bb and bˉ\bar{b}-hadrons, pair-produced at the Fermilab Tevatron collider. The data samples were collected with the Collider Detector at Fermilab (CDF) during the 1992-1995 collider run by triggering on the existence of μμ\mu \mu and eμe \mu candidates in an event. The observed ratio of LS to OS dileptons leads to a measurement of the average time-integrated mixing probability of all produced bb-flavored hadrons which decay weakly, χˉ=0.152±0.007\bar{\chi} = 0.152 \pm 0.007 (stat.) ±0.011\pm 0.011 (syst.), that is significantly larger than the world average χˉ=0.118±0.005\bar{\chi} = 0.118 \pm 0.005.Comment: 47 pages, 10 figures, 15 tables Submitted to Phys. Rev.

    Structural and functional analyses of minimal phosphopeptides targeting the polo-box domain of polo-like kinase 1

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    Polo-like kinase-1 (Plk1) has a pivotal role in cell proliferation and is considered a potential target for anticancer therapy. The noncatalytic polo-box domain (PBD) of Plk1 forms a phosphoepitope binding module for protein-protein interaction. Here, we report the identification of minimal phosphopeptides that specifically interact with the PBD of human PLK1, but not those of the closely related PLK2 and PLK3. Comparative binding studies and analyses of crystal structures of the PLK1 PBD in complex with the minimal phosphopeptides revealed that the C-terminal SpT dipeptide functions as a high-affinity anchor, whereas the N-terminal residues are crucial for providing specificity and affinity to the interaction. Inhibition of the PLK1 PBD by phosphothreonine mimetic peptides was sufficient to induce mitotic arrest and apoptotic cell death. The mode of interaction between the minimal peptide and PBD may provide a template for designing therapeutic agents that target PLK1.National Institutes of Health (U.S.) (Grant R01 GM60594)National Cancer Institute (U.S.)National Institutes of Health (U.S.) (Contract N01-CO-12400)National Institutes of Health (U.S.) (HHSN261200800001E

    Kinematic Sunyaev-Zel'dovich effect with ACT, DES, and BOSS: A novel hybrid estimator

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    The kinematic and thermal Sunyaev-Zel'dovich (kSZ and tSZ) effects probe the abundance and thermodynamics of ionized gas in galaxies and clusters. We present a new hybrid estimator to measure the kSZ effect by combining cosmic microwave background temperature anisotropy maps with photometric and spectroscopic optical survey data. The method interpolates a velocity reconstruction from a spectroscopic catalog at the positions of objects in a photometric catalog, which makes it possible to leverage the high number density of the photometric catalog and the precision of the spectroscopic survey. Combining this hybrid kSZ estimator with a measurement of the tSZ effect simultaneously constrains the density and temperature of free electrons in the photometrically selected galaxies. Using the 1000 deg2 of overlap between the Atacama Cosmology Telescope (ACT) Data Release 5, the first three years of data from the Dark Energy Survey (DES), and the Baryon Oscillation Spectroscopic Survey (BOSS) Data Release 12, we detect the kSZ signal at 4.8σ and reject the null (no-kSZ) hypothesis at 5.1σ. This corresponds to 2.0σ per 100,000 photometric objects with a velocity field based on a spectroscopic survey with 1/5th the density of the photometric catalog. For comparison, a recent ACT analysis using exclusively spectroscopic data from BOSS measured the kSZ signal at 2.1σ per 100,000 objects. Our derived constraints on the thermodynamic properties of the galaxy halos are consistent with previous measurements. With future surveys, such as the Dark Energy Spectroscopic Instrument and the Rubin Observatory Legacy Survey of Space and Time, we expect that this hybrid estimator could result in measurements with significantly better signal-to-noise than those that rely on spectroscopic data alone

    Membrane-mediated interactions

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    Interactions mediated by the cell membrane between inclusions, such as membrane proteins or antimicrobial peptides, play important roles in their biological activity. They also constitute a fascinating challenge for physicists, since they test the boundaries of our understanding of self-assembled lipid membranes, which are remarkable examples of two-dimensional complex fluids. Inclusions can couple to various degrees of freedom of the membrane, resulting in different types of interactions. In this chapter, we review the membrane-mediated interactions that arise from direct constraints imposed by inclusions on the shape of the membrane. These effects are generic and do not depend on specific chemical interactions. Hence, they can be studied using coarse-grained soft matter descriptions. We deal with long-range membrane-mediated interactions due to the constraints imposed by inclusions on membrane curvature and on its fluctuations. We also discuss the shorter-range interactions that arise from the constraints on membrane thickness imposed by inclusions presenting a hydrophobic mismatch with the membrane.Comment: 38 pages, 10 figures, pre-submission version. In: Bassereau P., Sens P. (eds) Physics of Biological Membranes. Springer, Cha

    The electromagnetic counterpart of the binary neutron star merger LIGO/Virgo GW170817. II. UV, optical, and near-infrared light curves and comparison to kilonova models

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    We present UV, optical, and near-infrared (NIR) photometry of the first electromagnetic counterpart to a gravitational wave source from Advanced Laser Interferometer Gravitational-wave Observatory (LIGO)/Virgo, the binary neutron star merger GW170817. Our data set extends from the discovery of the optical counterpart at 0.47–18.5 days post-merger, and includes observations with the Dark Energy Camera (DECam), Gemini-South/ FLAMINGOS-2 (GS/F2), and the Hubble Space Telescope (HST). The spectral energy distribution (SED) inferred from this photometry at 0.6 days is well described by a blackbody model with T » 8300 K, a radius of R » 4.5 ´ 1014 cm (corresponding to an expansion velocity of v » 0.3c), and a bolometric luminosity of Lbol » 5 ´ 10 41 erg s−1. At 1.5 days we find a multi-component SED across the optical and NIR, and subsequently we observe rapid fading in the UV and blue optical bands and significant reddening of the optical/ NIR colors. Modeling the entire data set, we find that models with heating from radioactive decay of 56Ni, or those with only a single component of opacity from r-process elements, fail to capture the rapid optical decline and red optical/NIR colors. Instead, models with two components consistent with lanthanide-poor and lanthanide-rich ejecta provide a good fit to the data; the resulting “blue” component has Mej » 0.01 M blue and v » 0.3 c ej blue , and the “red” component has Mej » 0.04 M red and v » 0.1 c ej red . These ejecta masses are broadly consistent with the estimated r-process production rate required to explain the Milky Way r-process abundances, providing the first evidence that binary neutron star (BNS) mergers can be a dominant site of r-process enrichment

    Probing Galaxy Evolution in Massive Clusters Using ACT and DES: Splashback as a Cosmic Clock

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    We measure the projected number density profiles of galaxies and the splashback feature in clusters selected by the Sunyaev–Zel'dovich effect from the Advanced Atacama Cosmology Telescope (AdvACT) survey using galaxies observed by the Dark Energy Survey (DES). The splashback radius is consistent with CDM-only simulations and is located at 2.40.4+0.3Mpch1{2.4}_{-0.4}^{+0.3}\,\mathrm{Mpc}\,{h}^{-1}. We split the galaxies on color and find significant differences in their profile shapes. Red and green-valley galaxies show a splashback-like minimum in their slope profile consistent with theory, while the bluest galaxies show a weak feature at a smaller radius. We develop a mapping of galaxies to subhalos in simulations and assign colors based on infall time onto their hosts. We find that the shift in location of the steepest slope and different profile shapes can be mapped to the average time of infall of galaxies of different colors. The steepest slope traces a discontinuity in the phase space of dark matter halos. By relating spatial profiles to infall time, we can use splashback as a clock to understand galaxy quenching. We find that red galaxies have on average been in clusters over 3.2 Gyr, green galaxies about 2.2 Gyr, while blue galaxies have been accreted most recently and have not reached apocenter. Using the full radial profiles, we fit a simple quenching model and find that the onset of galaxy quenching occurs after a delay of about a gigayear and that galaxies quench rapidly thereafter with an exponential timescale of 0.6 Gyr
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