Structural determinants in the group III truncated hemoglobin from Campylobacter jejuni.

Truncated hemoglobins (trHbs) constitute a distinct lineage in the globin superfamily, distantly related in size and fold to myoglobin and monomeric hemoglobins. Their phylogenetic analyses revealed that three groups (I, II, and III) compose the trHb family. Group I and II trHbs adopt a simplified globin fold, essentially composed of a 2-on-2 alpha-helical sandwich, wrapped around the heme group. So far no structural data have been reported for group III trHbs. Here we report the three-dimensional structure of the group III trHbP from the eubacterium Campylobacter jejuni. The 2.15-angstrom resolution crystal structure of C. jejuni trHbP (cyano-met form) shows that the 2-on-2 trHb fold is substantially conserved in the trHb group III, despite the absence of the Gly-based sequence motifs that were considered necessary for the attainment of the trHb specific fold. The heme crevice presents important structural modifications in the C-E region and in the FG helical hinge, with novel surface clefts at the proximal heme site. Contrary to what has been observed for group I and II trHbs, no protein matrix tunnel/cavity system is evident in C. jejuni trHbP. A gating movement of His(E7) side chain (found in two alternate conformations in the crystal structure) may be instrumental for ligand entry to the heme distal site. Sequence conservation allows extrapolating part of the structural results here reported to the whole trHb group III

The Coaxial L-P Cryogenic Receiver of the Sardinia Radio Telescope

The design and characterization of the coaxial dual-band L-P radio astronomical receiver for the prime focus of the Sardinia radio telescope are presented. The main feature of this receiver is to allow simultaneous radio astronomical observations in the P (305-410 MHz) and L (1.3-1.8 GHz) frequency bands. This functionality, which has been requested by the Pulsar research group at the National Institute for Astrophysics to estimate, among the others, the ionospheric dispersion in Pulsar observation, is currently missing in any other radio astronomical facility throughout the world. Also, single band operation is ensured by the proposed design both in linear and circular polarization, making this L-P receiver an ideal instrument for a wide range of radio astronomical and space applications. Some components of the receiver chain have been housed inside a cryostat and refrigerated at 20 K to reduce the noise temperature, resulting in a good performance compared to the receivers of other large radio telescopes. Several challenging issues have been faced in the design, mainly due to the large dimension and weight of the overall structure to be mounted in the prime focus position. Moreover, the design of the cryostat was constrained by the limited space available in the direction of the optical axis inside the focal cabin of the radio telescope, requiring a compact and light realization of the components of the receiver chain. This called for a home-made design of several devices, requiring a strong collaborative effort by researchers, engineers, and astronomers

Endometriosis and Organochlorinated Environmental Pollutants: A Case–Control Study on Italian Women of Reproductive Age

BACKGROUND: Endometriosis is a common gynecologic disease characterized by the ectopic growth of endometrial tissue. In industrialized countries, it affects approximately 10% of women of reproductive age. Its etiology is unclear, but a multifactorial origin is considered to be most plausible. Environmental organochlorinated persistent pollutants, in particular dioxins and polychlorinated biphenyls (PCBs), have been hypothesized to play a role in the disease etiopathogenesis. However, results of studies carried out on humans are conflicting. OBJECTIVE: We evaluated the exposure to organochlorinated persistent pollutants as a risk factor for endometriosis. METHODS: We conducted a case-control study in Rome on 158 women comprising 80 cases and 78 controls. In all women, serum concentrations of selected non-dioxin-like PCBs (NDL-PCBs) and dioxin-like PCBs (DL-PCBs), 1,1-dichloro-2,21-bis(4-chlorophenyl)-ethene (p p'-DDE), and hexachlorobenzene (HCB) were determined by ion-trap mass spectrometry. DR-CALUX bioassay was employed to assess the 2,3,7,8-tetrachlorodibenzo-p-dioxin toxicity equivalent (TEQ) concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and DL-PCBs. RESULTS: We found an increased risk of endometriosis for DL-PCB-118 (odds ratio (OR) = 3.79; 95% confidence interval (CI), 1.61-8.91), NDL-PCB-138 (OR = 3.78; 95% CI, 1.60-8.94), NDLPCB-153 (OR = 4.88; 95% CI, 2.01-11.0), NDL-PCB-170 (OR = 3.52; 95% CI, 1.41-8.79), and the sum of DL-PCBs and NDL-PCBs (OR = 5.63; 95% CI, 2.25-14. 10). No significant associations were observed with respect to HCB or to the sum of PCDDs, PCDFs1 and DL-PC13s given as total TEQs. CONCLUSIONS: The results of this study show that an association exists between increased PCB and p,p'-DDE serum concentrations and the risk of endometriosis

The Sardinia Radio Telescope Front-Ends

The 64 m diameter Sardinia Radio Telescope (SRT) has recently started an early science program using three cryogenic front-ends covering four bands: P-band (305-410 MHz), L-band (1.3-1.8 GHz), high C-band (5.7-7.7 GHz), K-band (18-26.5 GHz). The L- and the P-bands can be observed simultaneously with a single coaxial receiver installed at the primary focus, while a seven beam K-band receiver and a mono-feed high C-band receiver are installed, respectively at the secondary and beam waveguide focus. Additional front-ends are under construction to further expand the telescope observing capabilities. We report on the design and performance of the front-ends already installed on SRT and give an overview of the new ones to be completed in the near future

Status of the radio receiver system of the Sardina Radio Telescope

In this article, we present the design and performances of the radio receiver system installed at the Sardinia Radio Telescope (SRT). The three radio receivers planned for the first light of the Sardinian Telescope have been installed in three of the four possible focus positions. A dual linear polarization coaxial receiver that covers two frequency bands, the P-band (305-410 MHz) and the L-band (1.3-1.8 GHz) is installed at the primary focus. A mono-feed that covers the High C-band (5.7-7.7 GHz) is installed at the beam waveguide foci. A multi-beam (seven beams) K-band receiver (18- 26.5 GHz) is installed at the Gregorian focus. Finally, we give an overview about the radio receivers, which under test and under construction and which are needed for expanding the telescope observing capabilities

FIRST TESTS OF A TORALDO PUPIL OPTICAL MODULE FOR THE 32M MEDICINA ANTENNA

Toraldo Pupils can improve the angular resolving power of an optical instrument beyond the classical diffraction limit (hence the term “super-resolution”) using a filter consisting of finite- width concentric coronae with different amplitude and phase transmittance. Toraldo Pupils represent a viable approach to achieve super-resolution on antennas and radio telescopes. In this work we present a summary of the electromagnetic simulations and laboratory tests of a prototype optical module based on a Toraldo Pupil that has been field-tested on the Medicina 32-m radio telescope

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

The high-frequency upgrade of the Sardinia Radio Telescope

We present the status of the Sardinia Radio Telescope (SRT) and its forthcoming update planned in the next few years. The post-process scenario of the upgraded infrastructure will allow the national and international scientific community to use the SRT for the study of the Universe at high radio frequencies (up to 116 GHz), both in single dish and in interferometric mode. A telescope like SRT, operating at high frequencies, represents a unique resource for the scientific community. The telescope will be ideal for mapping quickly and with relatively high angular resolution extended radio emissions characterized by low surface brightness. It will also be essential for spectroscopic and polarimetric studies of both Galactic and extragalactic radio sources. With the use of the interferometric technique, SRT and the other Italian antennas (Medicina and Noto) will operate within the national and international radiotelescope network, allowing astronomers to obtain images of radio sources at very high angular resolution