The Fermi Large Area Telescope on Orbit: Event Classification, Instrument Response Functions, and Calibration

The Fermi Large Area Telescope (Fermi-LAT, hereafter LAT), the primary instrument on the Fermi Gamma-ray Space Telescope (Fermi) mission, is an imaging, wide field-of-view, high-energy -ray telescope, covering the energy range from 20 MeV to more than 300 GeV. During the first years of the mission the LAT team has gained considerable insight into the in-flight performance of the instrument. Accordingly, we have updated the analysis used to reduce LAT data for public release as well as the Instrument Response Functions (IRFs), the description of the instrument performance provided for data analysis. In this paper we describe the effects that motivated these updates. Furthermore, we discuss how we originally derived IRFs from Monte Carlo simulations and later corrected those IRFs for discrepancies observed between flight and simulated data. We also give details of the validations performed using flight data and quantify the residual uncertainties in the IRFs. Finally, we describe techniques the LAT team has developed to propagate those uncertainties into estimates of the systematic errors on common measurements such as fluxes and spectra of astrophysical sources

K-Space at TRECVID 2008

In this paper we describe K-Space’s participation in TRECVid 2008 in the interactive search task. For 2008 the K-Space group performed one of the largest interactive video information retrieval experiments conducted in a laboratory setting. We had three institutions participating in a multi-site multi-system experiment. In total 36 users participated, 12 each from Dublin City University (DCU, Ireland), University of Glasgow (GU, Scotland) and Centrum Wiskunde and Informatica (CWI, the Netherlands). Three user interfaces were developed, two from DCU which were also used in 2007 as well as an interface from GU. All interfaces leveraged the same search service. Using a latin squares arrangement, each user conducted 12 topics, leading in total to 6 runs per site, 18 in total. We officially submitted for evaluation 3 of these runs to NIST with an additional expert run using a 4th system. Our submitted runs performed around the median. In this paper we will present an overview of the search system utilized, the experimental setup and a preliminary analysis of our results

Spectroscopic ellipsometry and polarimetry for materials and systems analysis at the nanometer scale: state-of-the-art, potential, and perspectives

This paper discusses the fundamentals, applications, potential, limitations, and future perspectives of polarized light reflection techniques for the characterization of materials and related systems and devices at the nanoscale. These techniques include spectroscopic ellipsometry, polarimetry, and reflectance anisotropy. We give an overview of the various ellipsometry strategies for the measurement and analysis of nanometric films, metal nanoparticles and nanowires, semiconductor nanocrystals, and submicron periodic structures. We show that ellipsometry is capable of more than the determination of thickness and optical properties, and it can be exploited to gain information about process control, geometry factors, anisotropy, defects, and quantum confinement effects of nanostructures

GROWTH, REPRODUCTION, AND DEATH RATES OF <i>ESCHERICHIA COLI</i> AT INCREASED HYDROSTATIC PRESSURES

ZoBell, Claude E. (University of California, La Jolla) and Andre B. Cobet . Growth, reproduction, and death rates of Escherichia coli at increased hydrostatic pressures. J. Bacteriol. 84: 1228–1236. 1962.—Pressures ranging from 100 to 500 atm were found to retard the growth and reproduction of Escherichia coli in nutrient medium. Reproduction (as manifested by cell division or an increase in the number of viable cells) was retarded more than was growth (as manifested by increase in cell size or the formation of biomass). When incubated near the threshold of pressure tolerance (about 475 atm at 30 C), some cells of E. coli grew into long slender filaments showing little evidence of fission or cell division. Compression prolonged the lag phase of E. coli in nutrient medium, particularly at pressures higher than 400 atm. The inhibiting effects of pressure on reproduction and growth were found to be less at 30 than at 20 or 40 C. Pressures of 400 to 1,000 atm accelerated the death rate of E. coli cultures in nutrient medium. The lethal effects of pressure were greater at 40 than at 30 C and greater at 30 than at 20 C. </jats:p

FILAMENT FORMATION BY <i>ESCHERICHIA COLI</i> AT INCREASED HYDROSTATIC PRESSURES

ZoBell, Claude E. (University of California, La Jolla), and Andre B. Cobet . Filament formation by Escherichia coli at increased hydrostatic pressures. J. Bacteriol. 87: 710–719. 1964.—The reproduction as well as the growth of Escherichia coli is retarded by hydrostatic pressures ranging from 200 to 500 atm. Reproduction was indicated by an increase in the number of cells determined by plating on EMB Agar as well as by direct microscopic counts. Growth, which is not necessarily synonymous with reproduction, was indicated by increase in dry weight and protein content of the bacterial biomass. At increased pressures, cells of three different strains of E. coli tended to form long filaments. Whereas most normal cells of E. coli that developed at 1 atm were only about 2 μ long, the mean length of those that developed at 475 atm was 2.93 μ for strain R 4 , 3.99 μ for strain S, and 5.82 μ for strain B cells. Nearly 90% of the bacterial biomass produced at 475 atm by strain B was found in filaments exceeding 5 μ in length; 74.7 and 16.4% of the biomass produced at 475 atm by strains S and R 4 , respectively, occurred in such filaments. Strain R 4 formed fewer and shorter (5 to 35 μ) filaments than did the other two strains, whose filaments ranged in length from 5 to &gt;100 μ. The bacterial biomass produced at all pressures had approximately the same content of protein and nucleic acids. But at increased pressures appreciably more ribonucleic acid (RNA) and proportionately less deoxyribonucleic acid (DNA) was found per unit of biomass. Whereas the RNA content per cell increased with cell length, the amount of DNA was nearly the same in long filaments formed at increased pressure as in cells of normal length formed at 1 atm. The inverse relationship between the concentration of DNA and cell length in all three strains of E. coli suggests that the failure of DNA to replicate at increased pressure may be responsible for a repression of cell division and consequent filament formation. </jats:p

Control of an Estuarine Microfouling Sequence on Optical Surfaces Using Low-Intensity Ultraviolet Irradiation

Ultraviolet light has been investigated as an active energy input for the control of slime film formation on optical surfaces submerged in San Francisco Bay for periods up to 6 weeks. Irradiation of quartz underwater windows was carried out from three positions: (i) exterior to the window, (ii) from directly behind the window, and (iii) from the edge of the window with the ultraviolet (UV) energy refracted through the front of the window. Internally administered irradiation reaching levels of 10 to 30 μW per cm 2 measurable at the glass surface was effective in preventing bacterial slime film formation and settlement of metazoan larvae. When administered from the external position, over one order of magnitude more (500 to 600 μW/cm 2 ) UV energy was required to accomplish the same result. Irradiation from the edge position was most promising logistically and was effective in fouling control for 6 weeks. The results provide a preliminary quantitation of the energy requirement for control of the marine microfouling sequence which precedes development of macrofouling communities. </jats:p

The Fate of a Bunker Fuel in Beach Sand

ABSTRACT The dispersed oil concentrations in sand from three San Francisco area beaches have been measured over a 143 day period following an 840,000 gallon bunker fuel spill in San Francisco Bay. The dispersed oil remaining within the beaches after cleanup was extensively weathered while visible oil globules exhibited only minor weathering. Elevated levels of chloroform-extractable material were observed at two sampling locations following the spill. The background levels of chloroform-extractable materials determined from log-normal distribution analysis were ten-fold higher on bay beaches than on ocean beaches. Laboratory experiments indicated that in a beach system evaporation, dissolution, and microbial degradation combine to remove the lower molecular weight fractions of bunker fuel. A major effect of the beach is to disperse the oil. This dispersal has been shown to greatly enhance the effect of dissolution on the composition of bunker fuel. While the effect of exposure to water on the composition of a bunker fuel slick is minimal, significant amounts of the lower ends of bunker fuel (which is highly dispersed) in a sand column are removed by dissolution.</jats:p