Chromosomal distribution of interstitial telomeric sequences in nine neotropical primates (Platyrrhini): possible implications in evolution and phylogeny

To localize interstitial telomeric sequences (ITSs) and to test whether their pattern of distribution could be linked to chromosomal evolution, we hybridized telomeric sequence probes (peptide nucleic acid, PNA) on metaphases of New World monkeys: Callithrix argentata, Callithrix jacchus, Cebuella pygmaea, Saguinus oedipus, Saimiri sciureus, Aotus lemurinus griseimembra, Aotus nancymaae (Cebidae), Lagothrix lagotricha (Atelidae) and Callicebus moloch (Pithecidae), characterized by a rapid radiation and a high rate of chromosomal rearrangements. Our analysis of the probe signal localization allowed us to show in all the species analysed, as normally, the telomeric location at the terminal ends of chromosomes and unexpected signal distributions in some species. Indeed, in three species among the nine studied, Aotus lemurinus griseimembra, Aotus nancymaae (Cebidae) and Lagothrix lagotricha (Atelidae), we showed a high variability in terms of localization and degree of amplification of interstitial telomeric sequences, especially for the ones found at centromeric or pericentromeric positions (het-ITS). A comparative analysis, between species, of homologous chromosomes to human syntenies, on which we have found positive interspersed PNA signals, allowed us to explain the observed pattern of ITS distribution as results of chromosomal rearrangements in the neotropical primates analysed. This evidence permitted us to discuss the possible implication of ITSs as phylogenetic markers for closely related species. Moreover, reviewing previous literature data of ITSs distribution in Primates and in the light of our results, we suggest an underestimation of ITSs and highlight the importance of the molecular cytogenetics approach in characterizing ITSs, which role is still not clarified

Planck-LFI radiometers tuning

"This paper is part of the Prelaunch status LFI papers published on JINST: http://www.iop.org/EJ/journal/-page=extra.proc5/jinst" This paper describes the Planck Low Frequency Instrument tuning activities performed through the ground test campaigns, from Unit to Satellite Levels. Tuning is key to achieve the best possible instrument performance and tuning parameters strongly depend on thermal and electrical conditions. For this reason tuning has been repeated several times during ground tests and it has been repeated in flight before starting nominal operations. The paper discusses the tuning philosophy, the activities and the obtained results, highlighting developments and changes occurred during test campaigns. The paper concludes with an overview of tuning performed during the satellite cryogenic test campaign (Summer 2008) and of the plans for the just started in-flight calibration.Comment: This is an author-created, un-copyedited version of an article accepted for publication in JINST. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The definitive publisher authenticated version is available online at http://dx.doi.org/10.1088/1748-0221/4/12/T12013

Optimization of Planck/LFI on--board data handling

To asses stability against 1/f noise, the Low Frequency Instrument (LFI) onboard the Planck mission will acquire data at a rate much higher than the data rate allowed by its telemetry bandwith of 35.5 kbps. The data are processed by an onboard pipeline, followed onground by a reversing step. This paper illustrates the LFI scientific onboard processing to fit the allowed datarate. This is a lossy process tuned by using a set of 5 parameters Naver, r1, r2, q, O for each of the 44 LFI detectors. The paper quantifies the level of distortion introduced by the onboard processing, EpsilonQ, as a function of these parameters. It describes the method of optimizing the onboard processing chain. The tuning procedure is based on a optimization algorithm applied to unprocessed and uncompressed raw data provided either by simulations, prelaunch tests or data taken from LFI operating in diagnostic mode. All the needed optimization steps are performed by an automated tool, OCA2, which ends with optimized parameters and produces a set of statistical indicators, among them the compression rate Cr and EpsilonQ. For Planck/LFI the requirements are Cr = 2.4 and EpsilonQ <= 10% of the rms of the instrumental white noise. To speedup the process an analytical model is developed that is able to extract most of the relevant information on EpsilonQ and Cr as a function of the signal statistics and the processing parameters. This model will be of interest for the instrument data analysis. The method was applied during ground tests when the instrument was operating in conditions representative of flight. Optimized parameters were obtained and the performance has been verified, the required data rate of 35.5 Kbps has been achieved while keeping EpsilonQ at a level of 3.8% of white noise rms well within the requirements.Comment: 51 pages, 13 fig.s, 3 tables, pdflatex, needs JINST.csl, graphicx, txfonts, rotating; Issue 1.0 10 nov 2009; Sub. to JINST 23Jun09, Accepted 10Nov09, Pub.: 29Dec09; This is a preprint, not the final versio

Off-line radiometric analysis of Planck/LFI data

The Planck Low Frequency Instrument (LFI) is an array of 22 pseudo-correlation radiometers on-board the Planck satellite to measure temperature and polarization anisotropies in the Cosmic Microwave Background (CMB) in three frequency bands (30, 44 and 70 GHz). To calibrate and verify the performances of the LFI, a software suite named LIFE has been developed. Its aims are to provide a common platform to use for analyzing the results of the tests performed on the single components of the instrument (RCAs, Radiometric Chain Assemblies) and on the integrated Radiometric Array Assembly (RAA). Moreover, its analysis tools are designed to be used during the flight as well to produce periodic reports on the status of the instrument. The LIFE suite has been developed using a multi-layered, cross-platform approach. It implements a number of analysis modules written in RSI IDL, each accessing the data through a portable and heavily optimized library of functions written in C and C++. One of the most important features of LIFE is its ability to run the same data analysis codes both using ground test data and real flight data as input. The LIFE software suite has been successfully used during the RCA/RAA tests and the Planck Integrated System Tests. Moreover, the software has also passed the verification for its in-flight use during the System Operations Verification Tests, held in October 2008.Comment: Planck LFI technical papers published by JINST: http://www.iop.org/EJ/journal/-page=extra.proc5/1748-022

A Microwave Blackbody Target for Cosmic Microwave Background Spectral Measurements in the 10-20GHz range

The Tenerife Microwave Spectrometer (TMS) is a ground-based radio-spectrometer that will take absolute measurements of the sky between 10-20 GHz. To ensure the sensitivity and immunity to systematic errors of these measurements, TMS includes an internal calibration system optimised for the TMS band, and cooled down to 4 K. It consists of an Aluminium core, composed of a baseplate and a bed of pyramidal elements coated with an absorber material and a metallic shield. The absorber coating is made of a commercial resin ECCOSORB CR/MF 117. To achieve the high stability (+/- 1 mK/h), temperature homogeneity (thermal gradients {AT = 0.999) requirements of the reference unit, careful consideration has been given to the RF and thermal properties of the materials, as well as their geometry. In summary, this paper presents a comprehensive account of the design, characterisation, and test results of the TMS reference system.Comment: 45 pages, 36 figures, JINS

The Planck-LFI flight model composite waveguides

The Low Frequency Instrument on board the PLANCK satellite is designed to give the most accurate map ever of the CMB anisotropy of the whole sky over a broad frequency band spanning 27 to 77 GHz. It is made of an array of 22 pseudo-correlation radiometers, composed of 11 actively cooled (20 K) Front End Modules (FEMs), and 11 Back End Modules (BEMs) at 300K. The connection between the two parts is made with rectangular Wave Guides. Considerations of different nature (thermal, electromagnetic and mechanical), imposed stringent requirements on the WGs characteristics and drove their design. From the thermal point of view, the WG should guarantee good insulation between the FEM and the BEM sections to avoid overloading the cryocooler. On the other hand it is essential that the signals do not undergo excessive attenuation through the WG. Finally, given the different positions of the FEM modules behind the focal surface and the mechanical constraints given by the surrounding structures, different mechanical designs were necessary. A composite configuration of Stainless Steel and Copper was selected to satisfy all the requirements. Given the complex shape and the considerable length (about 1.5-2 m), manufacturing and testing the WGs was a challenge. This work deals with the development of the LFI WGs, including the choice of the final configuration and of the fabrication process. It also describes the testing procedure adopted to fully characterize these components from the electromagnetic point of view and the space qualification process they underwent. Results obtained during the test campaign are reported and compared with the stringent requirements. The performance of the LFI WGs is in line with requirements, and the WGs were successfully space qualified.Comment: this paper is part of the Prelaunch status LFI papers published on JINST: http://www.iop.org/EJ/journal/-page=extra.proc5/jins

Planck-LFI radiometers' spectral response

The Low Frequency Instrument (LFI) is an array of pseudo-correlation radiometers on board the Planck satellite, the ESA mission dedicated to precision measurements of the Cosmic Microwave Background. The LFI covers three bands centred at 30, 44 and 70 GHz, with a goal bandwidth of 20% of the central frequency. The characterization of the broadband frequency response of each radiometer is necessary to understand and correct for systematic effects, particularly those related to foreground residuals and polarization measurements. In this paper we present the measured band shape of all the LFI channels and discuss the methods adopted for their estimation. The spectral characterization of each radiometer was obtained by combining the measured spectral response of individual units through a dedicated RF model of the LFI receiver scheme. As a consistency check, we also attempted end-to-end spectral measurements of the integrated radiometer chain in a cryogenic chamber. However, due to systematic effects in the measurement setup, only qualitative results were obtained from these tests. The measured LFI bandpasses exhibit a moderate level of ripple, compatible with the instrument scientific requirements.Comment: 16 pages, 9 figures, this paper is part of the Prelaunch status LFI papers published on JINST: http://www.iop.org/EJ/journal/-page=extra.proc5/jins

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 $1/f$ 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

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