71 research outputs found
LFI 30 and 44 GHz receivers Back-End Modules
The 30 and 44 GHz Back End Modules (BEM) for the Planck Low Frequency
Instrument are broadband receivers (20% relative bandwidth) working at room
temperature. The signals coming from the Front End Module are amplified, band
pass filtered and finally converted to DC by a detector diode. Each receiver
has two identical branches following the differential scheme of the Planck
radiometers. The BEM design is based on MMIC Low Noise Amplifiers using GaAs
P-HEMT devices, microstrip filters and Schottky diode detectors. Their
manufacturing development has included elegant breadboard prototypes and
finally qualification and flight model units. Electrical, mechanical and
environmental tests were carried out for the characterization and verification
of the manufactured BEMs. A description of the 30 and 44 GHz Back End Modules
of Planck-LFI radiometers is given, with details of the tests done to determine
their electrical and environmental performances. The electrical performances of
the 30 and 44 GHz Back End Modules: frequency response, effective bandwidth,
equivalent noise temperature, 1/f noise and linearity are presented
“Publishing Is Mystical”: The Latinx Caucus Bibliography, Top-Tier Journals, and Minority Scholarship
In 2014, members of the NCTE/CCCC Latinx Caucus began contributing citations to a shared Google Document (GDoc) that suggested a relatively significant contribution of scholarship to the field of Rhetoric and Composition studies. Scholars of color have argued that rhetoric and composition scholarship fails to represent diversity in academic publications (Baca; Banks; Jones Royster; Pimentel; Ruíz). This study examines statistical data arrived at through analysis of the NCTE/CCCC Latinx Caucus Bibliography, with survey and interview data from Latinx scholars providing important context about publishing for people of color
Planck pre-launch status: Low Frequency Instrument calibration and expected scientific performance
We give the calibration and scientific performance parameters of the Planck
Low Frequency Instrument (LFI) measured during the ground cryogenic test
campaign. These parameters characterise the instrument response and constitute
our best pre-launch knowledge of the LFI scientific performance. The LFI shows
excellent stability and rejection of instrumental systematic effects;
measured noise performance shows that LFI is the most sensitive instrument of
its kind. The set of measured calibration parameters will be updated during
flight operations through the end of the mission.Comment: Accepted for publications in Astronomy and Astrophysics. Astronomy &
Astrophysics, 2010 (acceptance date: 12 Jan 2010
Deletion of methylglyoxal synthase gene (mgsA) increased sugar co-metabolism in ethanol-producing Escherichia coli
The use of lignocellulose as a source of sugars for bioproducts requires the development of biocatalysts that maximize product yields by fermenting mixtures of hexose and pentose sugars to completion. In this study, we implicate mgsA encoding methylglyoxal synthase (and methylglyoxal) in the modulation of sugar metabolism. Deletion of this gene (strain LY168) resulted in the co-metabolism of glucose and xylose, and accelerated the metabolism of a 5-sugar mixture (mannose, glucose, arabinose, xylose and galactose) to ethanol
The Quijote CMB Experiment
We present the current status of the QUIJOTE (Q-U-I JOint TEnerife) CMB
Experiment, a new instrument which will start operations early 2009 at Teide
Observatory, with the aim of characterizing the polarization of the CMB and
other processes of galactic and extragalactic emission in the frequency range
10-30 GHz and at large angular scales. QUIJOTE will be a valuable complement at
low frequencies for the PLANCK mission, and will have the required sensitivity
to detect a primordial gravitational-wave component if the tensor-to-scalar
ratio is larger than r=0.05.Comment: 9 pages, 5 figures. To appear in "Highlights of Spanish Astrophysics
V", Proceedings of the VIII Scientific Meeting of the Spanish Astronomical
Society (SEA) held in Santander, 7-11 July, 2008. Edited by J. Gorgas, L. J.
Goicoechea, J. I. Gonzalez-Serrano, J. M. Dieg
The status of the Quijote multi-frequency instrument
The QUIJOTE-CMB project has been described in previous publications. Here we present the current status of the QUIJOTE multi-frequency instrument (MFI) with five separate polarimeters (providing 5 independent sky pixels): two which operate at 10-14 GHz, two which operate at 16-20 GHz, and a central polarimeter at 30 GHz. The optical arrangement includes 5 conical corrugated feedhorns staring into a dual reflector crossed-draconian system, which provides optimal cross-polarization properties (designed to be < -35 dB) and symmetric beams. Each horn feeds a novel cryogenic on-axis rotating polar modulator which can rotate at a speed of up to 1 Hz. The science driver for this first instrument is the characterization of the galactic emission. The polarimeters use the polar modulator to derive linear polar parameters Q, U and I and switch out various systematics. The detection system provides optimum sensitivity through 2 correlated and 2 total power channels. The system is calibrated using bright polarized celestial sources and through a secondary calibration source and antenna. The acquisition system, telescope control and housekeeping are all linked through a real-time gigabit Ethernet network. All communication, power and helium gas are passed through a central rotary joint. The time stamp is synchronized to a GPS time signal. The acquisition software is based on PLCs written in Beckhoffs TwinCat and ethercat. The user interface is written in LABVIEW. The status of the QUIJOTE MFI will be presented including pre-commissioning results and laboratory testing
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