Development of a general purpose airborne simulator

Variable stability system development for General Purpose Airborne Simulator /GPAS

New measurements of cosmic infrared background fluctuations from early epochs

Cosmic infrared background fluctuations may contain measurable contribution from objects inaccessible to current telescopic studies, such as the first stars and other luminous objects in the first Gyr of the Universe's evolution. In an attempt to uncover this contribution we have analyzed the GOODS data obtained with the Spitzer IRAC instrument, which are deeper and cover larger scales than the Spitzer data we have previously analyzed. Here we report these new measurements of the cosmic infrared background (CIB) fluctuations remaining after removing cosmic sources to fainter levels than before. The remaining anisotropies on scales > 0.5 arcmin have a significant clustering component with a low shot-noise contribution. We show that these fluctuations cannot be accounted for by instrumental effects, nor by the Solar system and Galactic foreground emissions and must arise from extragalactic sources.Comment: Ap.J.Letters, in pres

Demonstrating the negligible contribution of optical ACS/HST galaxies to source-subtracted cosmic infrared background fluctuations in deep IRAC/Spitzer images

We study the possible contribution of optical galaxies detected with the {\it Hubble} ACS instrument to the near-IR cosmic infrared (CIB) fluctuations in deep {\it Spitzer} images. The {\it Spitzer} data used in this analysis are obtained in the course of the GOODS project from which we select four independent $10^\prime\times10^\prime$ regions observed at both 3.6 and 4.5 \um. ACS source catalogs for all of these areas are used to construct maps containing only their emissions in the ACS $B, V, i, z$-bands. We find that deep Spitzer data exhibit CIB fluctuations remaining after removal of foreground galaxies of a very different clustering pattern at both 3.6 and 4.5 \um than the ACS galaxies could contribute. We also find that there are very good correlations between the ACS galaxies and the {\it removed} galaxies in the Spitzer maps, but practically no correlations remain with the residual Spitzer maps used to identify the CIB fluctuations. These contributions become negligible on larger scales used to probe the CIB fluctuations arising from clustering. This means that the ACS galaxies cannot contribute to the large-scale CIB fluctuations found in the residual Spitzer data. The absence of their contributions also means that the CIB fluctuations arise at z\gsim 7.5 as the Lyman break of their sources must be redshifted past the longest ACS band, or the fluctuations have to originate in the more local but extremely low luminosity galaxies.Comment: Ap.J.Letters, in press. Minor revisions to mathc the accepted versio

Calibrating Array Detectors

The development of sensitive large format imaging arrays for the infrared promises to provide revolutionary capabilities for space astronomy. For example, the Infrared Array Camera (IRAC) on SIRTF will use four 256 x 256 arrays to provide background limited high spatial resolution images of the sky in the 3 to 8 micron spectral region. In order to reach the performance limits possible with this generation of sensitive detectors, calibration procedures must be developed so that uncertainties in detector calibration will always be dominated by photon statistics from the dark sky as a major system noise source. In the near infrared, where the faint extragalactic sky is observed through the scattered and reemitted zodiacal light from our solar system, calibration is particularly important. Faint sources must be detected on this brighter local foreground. We present a procedure for calibrating imaging systems and analyzing such data. In our approach, by proper choice of observing strategy, information about detector parameters is encoded in the sky measurements. Proper analysis allows us to simultaneously solve for sky brightness and detector parameters, and provides accurate formal error estimates. This approach allows us to extract the calibration from the observations themselves; little or no additional information is necessary to allow full interpretation of the data. Further, this approach allows refinement and verification of detector parameters during the mission, and thus does not depend on a priori knowledge of the system or ground calibration for interpretation of images.Comment: Scheduled for ApJS, June 2000 (16 pages, 3 JPEG figures

Short Courses: Flexible Learning Opportunities in Informatics

In today’s fast-paced, data-driven world, researchers need to have a good foundation in informatics to store, organize, process, and analyze growing amounts of data. However, not all degree programs offer such training. Obtaining training in informatics on your own can be a daunting task for both new and established researchers who have little informatics experience. Providing educational opportunities appropriate for various skill levels and that mesh with a full-time schedule can remove barriers and foster a collaborative, informatics-savvy community that is better equipped to push science forward. To enhance informatics education in bioinformatics, VCUs Wright Center for Clinical and Translational Research of- fers a complementary series of seminars and workshops. These short course offerings introduce attendees to bioinformatics concepts and applications, and provide hands-on experience using online Bioinformatics databases. Bioinformatics 101 (B101) is an 8-week long series of 1-hour seminars focused on introducing topics in bioinformatics related to Next Generation Sequencing (NGS). Lectures are application focused and include overviews of NGS technology, practical bioinformatics pipelines, and examples of how the technology can influence downstream bioinformatics analyses. Bioinformatics 102 (B102) is a 5-day, 2 hours per day workshop developed in collaboration with VCU Libraries that provides attendees with hands-on experience accessing and using public data repositories. Sessions include a brief lecture followed by hands-on exercises. A Certificate of Completion is awarded upon meeting certain criteria for either the 101 or 102 courses. Bioinformatics 101 has been offered 3 times with a combined total of 246 registrants, and Bioinformatics 102 has been offered twice with a total of 78 registrants (limited to 30 per session per day). From course surveys, 82% (n=108) and 95% (n=47) of respondents gave B101 and B102 a positive rating, respectively. In addition, 89% of B101 respondents indicated their knowledge was improved, with 100% of B102 respondents indicating the same. A total of 84 and 33 certificates have been awarded for B101 and B102, respectively. The Bioinformatics 101 and 102 courses have become highly anticipated across the university, and have gained the external attention of surrounding businesses and colleges. Registrants have diverse backgrounds including biological, clinical, computational, administrative, librarian, business, and others with a total of 77 departments across VCU and VCU Health represented. Due to this interest, Bioinformatics 101 began offering live online attendance to accommodate those who were unable to travel across campus, or who are attending from outside VCU. This past year, 50% of attendance was online indicating a growing need for flexible education opportunities in informatics. Increasing researcher knowledge of Bioinformatics along with awareness of university resources for informatics support fosters an informatics-savvy research community that is empowered to take advantage of existing and new data sources in the pursuit of new insights and scientific discoveries for the betterment of human health. Future work will include the development of a more comprehensive educational framework by creating new and flexible learning opportunities that will make informatics education easy and convenient for our dedicated researchers

The international origins of Hannah Arendt’s historical method

This article examines the multiple ways in which Hannah Arendt’s thought arose historically and in international context, but also how we might think about history and theory in new ways with Arendt. It is commonplace to situate Arendt’s political and historical thought as a response to totalitarianism. However, far less attention has been paid to the significance of other specifically and irreducibly international experiences and events. Virtually all of her singular contributions to political and international thought were influenced by her lived experiences of and historical reflections on statelessness and exile, imperialism, transnational totalitarianism, world wars, the nuclear revolution, the founding of Israel, war crimes trials, and the war in Vietnam. Yet we currently lack a comprehensive reconstruction of the extent to which Arendt’s thought was shaped by the fact of political multiplicity, that there are not one but many polities existing on earth and inhabiting the world. This neglect is surprising in light of the significant ‘international turn’ in the history of thought and intellectual history; the growing interest in Arendt’s thought within international theory; and, above all, Arendt’s own unwavering commitment to plurality not simply as a characteristic of individuals but as an essential and intrinsically valuable effect of distinct territorial entities. The article examines the historical and international context of Arendt’s historical method, including her critique of process- and development-oriented histories that remain current in different social science fields, setting out and evaluating her alternative approach to historical writing

Reconstructing emission from pre-reionization sources with cosmic infrared background fluctuation measurements by the JWST

We present new methodology to use cosmic infrared background (CIB) fluctuations to probe sources at 10<z<30 from a JWST/NIRCam configuration that will isolate known galaxies to 28 AB mag at 0.5--5 micron. At present significant mutually consistent source-subtracted CIB fluctuations have been identified in the Spitzer and Akari data at 2--5 micron, but we demonstrate internal inconsistencies at shorter wavelengths in the recent CIBER data. We evaluate CIB contributions from remaining galaxies and show that the bulk of the high-z sources will be in the confusion noise of the NIRCam beam, requiring CIB studies. The accurate measurement of the angular spectrum of the fluctuations and probing the dependence of its clustering component on the remaining shot noise power would discriminate between the various currently proposed models for their origin and probe the flux distribution of its sources. We show that the contribution to CIB fluctuations from remaining galaxies is large at visible wavelengths for the current instruments precluding probing the putative Lyman-break of the CIB fluctuations. We demonstrate that with the proposed JWST configuration such measurements will enable probing the Lyman break. We develop a Lyman-break tomography method to use the NIRCam wavelength coverage to identify or constrain, via the adjacent two-band subtraction, the history of emissions over 10<z<30 as the Universe comes out of the 'Dark Ages'. We apply the proposed tomography to the current Spitzer/IRAC measurements at 3.6 and 4.5 micron, to find that it already leads to interestingly low upper limit on emissions at z>30.Comment: ApJ, in press. Minor revisions/additions to match the version in proof

Arendt and political realism: towards a realist account of political judgement

This article argues that Hannah Arendt’s thought can offer significant insights on political judgement for realism in political theory. We identify a realist position which emphasises the need to account for how humans judge politically, contra moralist tendencies to limit its exercise to rational standards, but which fails to provide a sufficient conception of its structure and potential. Limited appeals to political judgement render the realist defence of the political elusive, and compromise the endeavour to offer a meaningful alternative to the moralist tendency to displace politics. The potential and limitations of realist discussions on judgement are made visible in relation to proto-realists Judith Shklar and Isaiah Berlin. In seeking to enrich the realist conception of the political, the article introduces the displacement critique found in the neglected Arendtian ‘realism’. It also provides the foundations for a distinctly realist account of political judgement which, we argue, requires elaboration along two dimensions: the social coding of political judgement and the political capacities that help judgement build a suitable political sphere