836 research outputs found
Deborah Mauskopf Deliyannis, éd. trad. — Agnellus of Ravenna. The Book of Pontiffs of the Church of Ravenna. Washington, Univ. of America Press, 2004 (Medieval Texts in translation)
No full textPalazzo Éric. Deborah Mauskopf Deliyannis, éd. trad. — Agnellus of Ravenna. The Book of Pontiffs of the Church of Ravenna. Washington, Univ. of America Press, 2004 (Medieval Texts in translation). In: Cahiers de civilisation médiévale, 50e année (n°197), Janvier-mars 2007. p. 89
Cosmic microwave background
No full textThis chapter describes the origin and characteristics of the Cosmic Microwave Background radiation, the source of most of the millimeter wave photons in the universe. The measurements from the COBE satellite of the temperature and morphology of the CMB on large angular scales are summarized. The theoretical origin of anisotropies in the CMB and the predicted power spectrum of fluctuations is presented. These power spectra are shown to have a strong dependence on the cosmological parameters Ω0, Ωb, H0, ΩΛ, n. Current millimeter-wave experiments are approaching the sensitivity levels necessary to accurately determine some of these parameters
CASPER: Concordia atmospheric spectroscopy of emitted radiation
No full textCASPER (Concordia Atmospheric Spectroscopy of Emitted Radiation) is a spectrometer proposed for installation at Dome C, devoted to measurements of atmospheric emission in the spectral region between 180 μm and 3 mm (3-55 cm-1). This instrument will be able to perform continuous spectral sampling at different altitudes at angular scales of ∼1°. From the recorded data it is possible to extract atmospheric transmittance within 1% in the whole wide operating band, together with water vapour content and O 2 and O3 concentrations. CASPER will allow us to characterize the site for future FIR/mm telescopes. Atmospheric data recorded by CASPER will allow for correction of astrophysical and cosmological observations without the need for telescope-specific procedures and further loss of observation time with more precision in the observations themselves. Calibration of ground-based telescopes on known sky sources is strongly affected by atmospheric absorption. CASPER has this as its primary goal. The spectrometer is based on a Martin-Puplett interferometer. Two data sampling solutions will be performed: phase modulation & fast scan strategy. Sky radiation is collected towards the interferometer by an optical setup that allows the field of view, to explore the full 0 ÷ 90° range of elevation angles. With a low spurious polarization instrument, monitoring of polarized atmospheric contribution will be possible. © EAS, EDP Sciences 2005
Far infrared polarimeter with very low instrumental polarization
No full textAfter a short analysis of the main problems involved in the construction of a Far Infrared polarimeter with
very low instrumental noise, we describe the instrument that will be employed at MITO telescope to search for
calibration sources and investigate polarization near the CMB anisotropy peaks in the next campaign (Winter
2002-03)
LEKIDs Development for mm-Wave Astronomy
No full textMicrowave Kinetic Inductance Detectors (MKIDs) have recently drawn the attention of the low-temperature detectors community. Easy fabrication, high sensitivity, small time constants and most notably the intrinsic capability to frequency
multiplexing open new possibilities to applications that need very large array sizes and/or high speed read-out. Lumped Element Kinetic Inductance Detectors (LEKIDs) designed and fabricated in our collaboration have already shown good on sky performances,
but new developments are needed for future multi-thousands-pixels instruments.
In this contribution we present such ongoing developments: a new LEKIDs design, optimized to be dual polarization sensitive; use of new materials such as TiN iin order to reach better signal to noise ratios; new solutions to minimize the crosstalk
between pixels in order to achieve a better control of the resonance positions in frequency space. We discuss present lab measurements of the optical performances and recent improvements of the read-out electronics
Foregrounds: Unveiling the galactic weather to the CMB
No full textCosmic Microwave Background observations became the tool to probe the the first events of cosmic history. After WMAP data releases, galactic and extragalactic foregrounds are perceived as the main limiting uncertainity for the near-future search for the B-mode polarization inprints from the inflationary era, either through satellites or ground-based experiments like Brain at Dome-C. A combination of technology, scanning strategy and above all, accurate knowledge of polarized foregrounds will be necessary for an optimal mapping of B-mode CMB Polarization. In addition, the search for a better understanding of the galactic foregrounds will provide unprecedented knowledge on the Milky Way structure and star formation. © 2010 EAS, EDP Sciences
A High Spatial Resolution Analysis of the MAXIMA-1 Cosmic Microwave Background Anisotropy Data
No full textWe extend the analysis of the MAXIMA-1 cosmic microwave background (CMB) data to smaller angular scales. MAXIMA, a bolometric balloon experiment, mapped a 124 deg region of the sky with 10\arcmin resolution at frequencies of 150, 240 and 410 GHz during its first flight. The original analysis, which covered the multipole range , is extended to using data from three 150 GHz photometers in the fully cross-linked central 60 deg of the map. The main improvement over the original analysis is the use of 3\arcmin square pixels in the calculation of the map. The new analysis is consistent with the original for , where inflationary models predict a third acoustic peak, the new analysis shows power with an amplitude of \microk at in excess to the average power of \microk in the range
When is a life too costly to save? : evidence from U.S. environmental regulations
No full textExcept for two relatively minor statutes, U.S. environmental laws do not permit the balancing of costs and benefits in setting environmental standards. The Clean Air Act, for example, prohibits the Environmental Protection Agency (EPA) from considering costs in setting ambient air quality standards. Similarly, the Clean Water Act does not allow consideration of benefits in setting effluent standards. When the EPA is allowed to balance benefits against costs, it has considerable discretion in defining"balancing."The authors ask two questions: Whether allowed to or not, has the EPA balanced costs and benefits in setting environmental standards? Where has the EPA drawn the line in deciding how much to spend to save a statistical life? Their answers are based on data about the costs and benefits of regulations involving three classes of pollutants: cancer-causing pesticides usedon food crops (1975-89); carcinogenic air pollutants (1975-90); and all uses of asbestos regulated under the Toxic Substances Control Act. The following are their findings. The EPA behaved as though it were balancing costs and benefits in its regulation of pesticides under Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) and of asbestos under Toxic Substance Control Act (TSCA), the two so-called balancing statutes. The higher the cost of the ban, the less likely the EPA was to ban the use of these products. The greater the number of lives saved, the more likely the EPA was to ban their use. But the amount the EPA was (implicitly) willing to spend to save a life was high: 49 million to avoid cancer through exposure to asbestos. The value the EPA attached to saving a life was higher for workers than for consumers. The value attached to avoiding a case of cancer through exposure to pesticide resides on food was less than 52 million value of preventing cancer among pesticide applicators - perhaps because workers are exposed to higher levels of pollution than consumers. After 1987, when the Natural Resources Defense Council sued the EPA for considering costs in setting emissions standards for vinyl chloride, the EPA considered costs in setting emissions standards only after an acceptable level of risk was achieved. Ironically, before the vinyl chloride decision, the value per cancer case avoided was only $15 million. The amount the EPA was willing to spend to save a life was thus less under the Clean Air Act than under the balancing statutes. But after this decision, the EPA did not consider costs at all if the risk of cancer to the maximally exposed individual was above one in 10,000.Environmental Economics&Policies,Health Monitoring&Evaluation,Economic Theory&Research,Health Economics&Finance,Montreal Protocol
Design and Electrical Performance of the Kinetic Inductance Detectors of the OLIMPO Experiment
No full textWe are going to describe the design and the electrical performance of the horn-coupled lumped element kinetic inductance detectors (LEKIDs) for the OLIMPO experiment. OLIMPO is a balloon-borne mission, devoted to the study of the largest structures in the Universe, by detecting the Sunyaev-Zel'dovich effect of the Cosmic Microwave Background (CMB) photons crossing clusters of galaxies. The multi-band focal planes (centered at 150, 200, 350 and 480 GHz), large aperture telescope (2.6 m), photometric and spectrometer configuration (OLIMPO is equipped with a plug-in differential Fourier transform spectrometer) make OLIMPO able to characaterise all the components of the Sunyaev-Zel'dovich effect with unprecedented precision. The design of the LEKIDs has been optimised to cope with a wide range of optical loadings (corresponding to both photometric and spectrometric configurations). The electrical characterisation of the LEKID arrays was performed in the OLIMPO cryostat, at a temperature around 300 mK and under a constant optical load lower than 500 fW. The readout electronics is a customised ROACH-2 coupled to a MUSIC DAC/ADC board. The averaged responsivities for the arrays, measured from the phase readout, are 1.18x1011rad/W for the 150 GHz array, 4.10x1010rad/W for the 200 GHz array, 1.09x1012rad/W for the 350 GHz array, and 4.41x1011rad/W for the 480 GHz array. Therefore, measuring the spectral noise density for each pixels of the arrays, whose average values are 2.5x10-5rad/Hz(1/2)for the 150 GHz array, 3.6x10-5rad/Hz(1/2)for the 200 GHz array, 5.1x10-5rad/Hz(1/2)for the 350 GHz array, and 1.9x10-5rad/Hz(1/2)for the 480 GHz array, we obtained the values of the averaged electrical noise equivalent power (NEP) over all the arrays: 2x10-16W/Hz(1/2), 9x10-16W/Hz(1/2), 5x10-17W/Hz(1/2), and 4x10-17W/Hz(1/2)respectively for the four OLIMPO arrays
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