The Sardinia Space Communication Asset: Performance of the Sardinia Deep Space Antenna X-Band Downlink Capability

The Sardinia deep space antenna (SDSA), managed by the Italian Space Agency (ASI) has started its operations in 2017 aiming to provide tracking and communication services for deep space, near earth, and lunar missions, and to support new and challenging radio science experiments. The SDSA shares with the Sardinia Radio Telescope (SRT) a part of the system and infrastructure, but has its own specific equipment and a dedicated control center. The current SDSA capabilities involve the X-band (8.4 GHz-8.5 GHz) reception of telemetry from deep space probes within interplanetary missions. In this work we describe the development and performance of the X-band receiving system. It was designed and assembled with the cooperation of both the NASA-Jet Propulsion Laboratory (JPL) and the European Space Agency (ESA). Specifically, NASA-JPL provided the X-band feed and the cryogenic receiver installed in a suitable focus of the SRT devoted to space applications, and ESA provided the intermediate frequency modem system (IFMS) for signal processing. The coupling of the X-band feed with the parabolic reflector of the SRT and the radiating features of the SDSA have been evaluated with simulations performed using CST Studio Suite and GRASP by Ticra. The telecommunication performance of the system has been assessed by measurements and experiments showing a good agreement between estimates and simulations

Imaging of SNR IC443 and W44 with the Sardinia Radio Telescope at 1.5 GHz and 7 GHz

Observations of supernova remnants (SNRs) are a powerful tool for investigating the later stages of stellar evolution, the properties of the ambient interstellar medium, and the physics of particle acceleration and shocks. For a fraction of SNRs, multi-wavelength coverage from radio to ultra high-energies has been provided, constraining their contributions to the production of Galactic cosmic rays. Although radio emission is the most common identifier of SNRs and a prime probe for refining models, high-resolution images at frequencies above 5 GHz are surprisingly lacking, even for bright and well-known SNRs such as IC443 and W44. In the frameworks of the Astronomical Validation and Early Science Program with the 64-m single-dish Sardinia Radio Telescope, we provided, for the first time, single-dish deep imaging at 7 GHz of the IC443 and W44 complexes coupled with spatially-resolved spectra in the 1.5-7 GHz frequency range. Our images were obtained through on-the-fly mapping techniques, providing antenna beam oversampling and resulting in accurate continuum flux density measurements. The integrated flux densities associated with IC443 are S_1.5GHz = 134 +/- 4 Jy and S_7GHz = 67 +/- 3 Jy. For W44, we measured total flux densities of S_1.5GHz = 214 +/- 6 Jy and S_7GHz = 94 +/- 4 Jy. Spectral index maps provide evidence of a wide physical parameter scatter among different SNR regions: a flat spectrum is observed from the brightest SNR regions at the shock, while steeper spectral indices (up to 0.7) are observed in fainter cooling regions, disentangling in this way different populations and spectra of radio/gamma-ray-emitting electrons in these SNRs.Comment: 13 pages, 9 figures, accepted for publication to MNRAS on 18 May 201

Quantum ESPRESSO toward the exascale

Quantum ESPRESSO is an open-source distribution of computer codes for quantum-mechanical materials modeling, based on density-functional theory, pseudopotentials, and plane waves, and renowned for its performance on a wide range of hardware architectures, from laptops to massively parallel computers, as well as for the breadth of its applications. In this paper, we present a motivation and brief review of the ongoing effort to port Quantum ESPRESSO onto heterogeneous architectures based on hardware accelerators, which will overcome the energy constraints that are currently hindering the way toward exascale computing

Exploratory Genome-Wide Association Analysis to Identify Pharmacogenetic Determinants of Response to R-CHOP in Diffuse Large B-Cell Lymphoma

R-CHOP standard chemotherapy is successful in about 60% of diffuse large B-cell lymphoma (DLBCL) patients. Unresponsive patients have a poor prognosis, and predictive biomarkers of response to R-CHOP are lacking. We conducted the first prospective GWAS study aimed at exploring constitutional biomarkers predictive of R-CHOP efficacy and toxicity. Overall, 216 any-stage chemonaive DLBCL patients candidate to R-CHOP were enrolled. The median age of the 185 eligible patients was 59.2 years, 49.7% were women and 45.4% were stage I-II patients. According to the Revised International Prognostic Index (R-IPI), 14.1%, 56.8% and 29.2% were in the very good, good and poor prognosis groups, respectively. Of the patients, 85.9% produced a complete response. Highly significant associations (i.e., p < 5 x 10(-8)) were found between progression-free survival (PFS) and six SNPs (i.e., rs116665727, rs1607795, rs75614943, rs77241831, rs117500207, rs78466241). Additionally, five SNPs (i.e., rs74832512, rs117500207, rs35789195, rs11721010, rs12356569) were highly associated with overall survival (OS). Wild-type patients showed a prolonged PFS or OS compared with patients carrying deleterious alleles (p < 0.001). No association with the adequate significant threshold was observed between SNPs and the objective response or toxicity. In the future, these SNPs, alone or in combination, after a proper validation in an independent cohort, could contribute to improving the prediction of R-CHOP response

Expression of Mutant or Cytosolic PrP in Transgenic Mice and Cells Is Not Associated with Endoplasmic Reticulum Stress or Proteasome Dysfunction

The cellular pathways activated by mutant prion protein (PrP) in genetic prion diseases, ultimately leading to neuronal dysfunction and degeneration, are not known. Several mutant PrPs misfold in the early secretory pathway and reside longer in the endoplasmic reticulum (ER) possibly stimulating ER stress-related pathogenic mechanisms. To investigate whether mutant PrP induced maladaptive responses, we checked key elements of the unfolded protein response (UPR) in transgenic mice, primary neurons and transfected cells expressing two different mutant PrPs. Because ER stress favors the formation of untranslocated PrP that might aggregate in the cytosol and impair proteasome function, we also measured the activity of the ubiquitin proteasome system (UPS). Molecular, biochemical and immunohistochemical analyses found no increase in the expression of UPR-regulated genes, such as Grp78/Bip, CHOP/GADD153, or ER stress-dependent splicing of the mRNA encoding the X-box-binding protein 1. No alterations in UPS activity were detected in mutant mouse brains and primary neurons using the UbG76V-GFP reporter and a new fluorogenic peptide for monitoring proteasomal proteolytic activity in vivo. Finally, there was no loss of proteasome function in neurons in which endogenous PrP was forced to accumulate in the cytosol by inhibiting cotranslational translocation. These results indicate that neither ER stress, nor perturbation of proteasome activity plays a major pathogenic role in prion diseases

SRT performance measurements (2018-2021)

Tests of characterization are periodically performed at SRT in order to check the status of the antenna, ensure a good functioning of the different components (e.g. active surface, receivers, backends, etc), and improve the observing performances at the different frequencies. In particular, the tests include measurements of beam shape, pointing, gain curves and focus for the different receivers (L, C, X and K-bands). We report the results of the main tests carried out after a long stop of the antenna due to the reparation of the main servo motors chillers in 2020 and compare them with those carried out during the recommissioning in 2018 (after the change of the actuators of the active surface). These results will be useful in order to compare the new status of the antenna after the upgrade of the new receivers at higher frequency (PON)

Front-Ends and Phased Array Feeds for the Sardinia Radio Telescope

We describe the design and performance of the Front- Ends for the 64-m diameter Sardinia Radio Telescope (SRT). An early science program was completed with SRT in August 2016, following a successful technical and scientific commissioning of the telescope and of its instrumentation. We give an overview of the three cryogenic Front-Ends, covering four bands, that were deployed on SRT during the early science program: P-band (305-410 MHz), L-band (1.3-1.8 GHz), high C-band (5.7- 7.7 GHz) and K-band (18-26.5 GHz). In addition, we describe the cryogenic Front-Ends that are currently under development, among which a seven beam for S-band (3.0-4.5 GHz) a mono-feed for Low-Cband (4.2-5.6 GHz), a 19-element for Q-band (33-50 GHz) and a mono-feed for a 3 mm band. Finally, we describe the development status of a demonstrator of a cryogenic C-band Phased Array Feed (PAF) for potential use at the SRT primary focus

Design of cryogenic phased array feed for 4-8 GHz

We describe the design and architecture of PHAROS2, a cryogenically cooled 4-8 GHz Phased Array Feed (PAF) demonstrator with a digital beamformer for radio astronomy application. The instrument will be capable of synthesizing four independent single-polarization beams by combining 24 active elements of an array of Vivaldi antennas. PHAROS2, the upgrade of PHAROS (PHased Arrays for Reflector Observing Systems), features: a) commercial cryogenic LNAs with state-of-the-art performance, b) a “Warm Section” for signal filtering, conditioning and single downconversion to select a ≈275 MHz Intermediate Frequency (IF) bandwidth within the 4-8 GHz Radio Frequency (RF) band, c) an IF signal transportation by analog WDM (Wavelength Division Mutiplexing) fiber-optic link, and d) a FPGA-based Italian Tile Processing Module (iTPM) digital backend.peer-reviewe