18 research outputs found

    Race and the Legacy of the First World War in French Anti-Colonial Politics of the 1920s

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    There has been relatively little historical research on the small number of African veterans who stayed on in France after the First World War and became militants in the radical anti-colonial movements created in the 1920s. From his entry onto the political stage in late 1924 until his early death three years later, the most celebrated and feared of these anti-colonial militants was Lamine Senghor, a decorated war veteran from Senegal. This chapter will chart Senghor’s brief career as an activist, focusing primarily on the ways in which he projected his identity as a veteran in his speeches and writings, as well as exploring, more generally, how France’s “blood debt” to its colonial subjects became a key theme of anti-colonial discourse in the interwar period

    The NANOGrav 11-year Data Set: High-precision Timing of 45 Millisecond Pulsars

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    We present high-precision timing data over time spans of up to 11 years for 45 millisecond pulsars observed as part of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) project, aimed at detecting and characterizing low-frequency gravitational waves. The pulsars were observed with the Arecibo Observatory and/or the Green Bank Telescope at frequencies ranging from 327 MHz to 2.3 GHz. Most pulsars were observed with approximately monthly cadence, and six high-timing-precision pulsars were observed weekly. All were observed at widely separated frequencies at each observing epoch in order to fit for time-variable dispersion delays. We describe our methods for data processing, time-of-arrival (TOA) calculation, and the implementation of a new, automated method for removing outlier TOAs. We fit a timing model for each pulsar that includes spin, astrometric, and (for binary pulsars) orbital parameters; time-variable dispersion delays; and parameters that quantify pulse-profile evolution with frequency. The timing solutions provide three new parallax measurements, two new Shapiro delay measurements, and two new measurements of significant orbital-period variations. We fit models that characterize sources of noise for each pulsar. We find that 11 pulsars show significant red noise, with generally smaller spectral indices than typically measured for non-recycled pulsars, possibly suggesting a different origin. A companion paper uses these data to constrain the strength of the gravitational-wave background

    The NANOGrav Nine-year Data Set:Observations, Arrival Time Measurements, and Analysis of 37 Millisecond Pulsars

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    We present high-precision timing observations spanning up to nine years for 37 millisecond pulsars monitored with the Green Bank and Arecibo radio telescopes as part of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) project. We describe the observational and instrumental setups used to collect the data, and methodology applied for calculating pulse times of arrival; these include novel methods for measuring instrumental offsets and characterizing low signal-to-noise ratio timing results. The time of arrival data are fit to a physical timing model for each source, including terms that characterize time-variable dispersion measure and frequency-dependent pulse shape evolution. In conjunction with the timing model fit, we have performed a Bayesian analysis of a parameterized timing noise model for each source, and detect evidence for excess low-frequency, or "red," timing noise in 10 of the pulsars. For 5 of these cases this is likely due to interstellar medium propagation effects rather than intrisic spin variations. Subsequent papers in this series will present further analysis of this data set aimed at detecting or limiting the presence of nanohertz-frequency gravitational wave signals

    Tuning Interfacial Electron Transfer in Nanostructured Cuprous Oxide Photoelectrochemical Cells with Charge-Selective Molecular Coatings

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    The coating of nanostructured films of cuprous oxide with electroactive molecules strongly affects their photoelectrochemical performance in nonaqueous photocells, with photocurrent density increased up to an order of magnitude relative to bare cuprous oxide films or almost completely suppressed, depending on the choice of molecular adsorbant. Among adsorbants that enhance photocurrent, a strong variance of photoelectrochemical behavior is observed with changes in the molecular structure of the sensitizer, associated with differences in the reorganization energy and molecular size, which are interpreted to enhance forward electron transport and impede electrolyte/photocathode recombination, respectively. These results demonstrate that nanostructured cuprous oxide is a promising cathode material for p-type dye-sensitized solar cells

    Characterization of Genomic Alterations in Radiation-Associated Breast Cancer among Childhood Cancer Survivors, Using Comparative Genomic Hybridization (CGH) Arrays

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    <div><p>Ionizing radiation is an established risk factor for breast cancer. Epidemiologic studies of radiation-exposed cohorts have been primarily descriptive; molecular events responsible for the development of radiation-associated breast cancer have not been elucidated. In this study, we used array comparative genomic hybridization (array-CGH) to characterize genome-wide copy number changes in breast tumors collected in the Childhood Cancer Survivor Study (CCSS). Array-CGH data were obtained from 32 cases who developed a second primary breast cancer following chest irradiation at early ages for the treatment of their first cancers, mostly Hodgkin lymphoma. The majority of these cases developed breast cancer before age 45 (91%, n = 29), had invasive ductal tumors (81%, n = 26), estrogen receptor (ER)-positive staining (68%, n = 19 out of 28), and high proliferation as indicated by high Ki-67 staining (77%, n = 17 out of 22). Genomic regions with low-copy number gains and losses and high-level amplifications were similar to what has been reported in sporadic breast tumors, however, the frequency of amplifications of the 17q12 region containing human epidermal growth factor receptor 2 (HER2) was much higher among CCSS cases (38%, n = 12). Our findings suggest that second primary breast cancers in CCSS were enriched for an “amplifier” genomic subgroup with highly proliferative breast tumors. Future investigation in a larger irradiated cohort will be needed to confirm our findings.</p></div

    Patient characteristics and treatment of CCSS cases included in this study.

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    <p>Abbreviations: HL = Hodgkin lymphoma, NHL = non-Hodgkin lymphoma, RT = radiotherapy, UNK = unknown.</p><p><sup>a</sup>0 = no direct treatment to the chest, UNK = unknown dose, >0 and < 70 Gy = direct treatment to the chest, SL = (low scatter) patient had RT, but not to the chest or an adjacent body region, SH = (high scatter) patient had RT that included arm, neck or abdomen but not chest.</p><p>Patient characteristics and treatment of CCSS cases included in this study.</p

    Breast tumor characteristics of CCSS cases included in this study.

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    <p>Abbreviations: BC = breast cancer, DCIS = ductal cell in situ, ER = estrogen receptor, ND = not determined, UNK = unknown.</p><p><sup>a</sup>Grade: low = well differentiated or grade I, intermediate = moderately differentiated or grade II, high = poorly differentiated or grade III.</p><p>Breast tumor characteristics of CCSS cases included in this study.</p
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