Reflective Toraldo pupil for high-resolution millimeter-wave astronomy

A novel, to the best of our knowledge, beam-shaping reflective surface for high-resolution millimeter/ submillimeter-wave astronomy instruments is presented. The reflector design is based on Toraldo’s superresolution principle and implemented with annulated binary-phase coronae structure inspired by the achromatic magnetic mirror approach. A thin, less than half a free-space wavelength, reflective Toraldo pupil device operated in the W-band has been fabricated using mesh-filter technology developed at Cardiff University. The device has been characterized on a quasi-optical test bench and demonstrated expected reduction of the beam width upon reflection at oblique incidence, while featuring a sidelobe level lower than −10 dB. The proposed reflective Toraldo pupil structure can be easily scaled for upper millimeter and infrared frequency bands as well as designed to transform a Gaussian beam into a flat-top beam with extremely low sidelobe level

Calcium antagonist induced vasodilation in peripheral, coronary and cerebral vasculature as important factors in the treatment of elderly hypertensives

Increased arteriolar tone is the pathophysiological hallmark of essential hypertension and is determined by the intracellular free calcium concentration in the vascular smooth muscle cell. Calcium influx is an important determinant of vasoconstriction and excess calcium influx-dependent vasoconstriction has been shown by plethysmographical studies in patients with essential hypertension. Calcium antagonists acutely lower BP by reducing calcium influx, calcium concentration and peripheral resistance. The degree of the attendant sympathetic nerve reflex activation and counter-regulatory mechanisms determines the antihypertensive response of the individual. Chronic monotherapy with a calcium antagonist results in an antihypertensive response, which is directly related to the patient's age and pretreatment BP and indirectly related to plasma renin levels. The resulting reduction in after-load neither leads to reduced cerebral blood flow in hypertensive patients, nor aggravates congestive heart failure. Calcium antagonists are a useful alternative to diuretics, primarily in older patients with low renin levels, either alone or combined with any other antihypertensive drug, and provide effective and safe control of blood pressur

Comparative Effects of Haemodialysis and Haemofiltration on Plasma Atrial Natriuretic Peptide

The effects of 4 h haemodialysis (15 patients) or 4 h haemofiltration (five patients) on plasma concentrations of atrial natriuretic peptide (ANP) were compared by means of a sensitive radioreceptor binding assay, and related to accompanying changes in body weight, blood pressure and plasma renin activity. Before dialysis, plasma ANP concentrations were considerably elevated: haemodialysis group 10-484 pmol/l (mean 156 pmol/l); haemofiltration group 72-320 pmol/l (mean 170 pmol/l). Although plasma concentrations of ANP fell markedly with treatment in both groups: post-haemodialysis 2-187 pmol/l (mean 67 pmol/l); post-haemofiltration 47-135 pmol/l (mean 79 pmol/l), after treatment it remained above the normal range in 14 of the 20 patients. Pretreatment plasma ANP was related to systolic blood pressure (r=0.459; P<0.05) but bore no relationship to mean or diastolic blood pressure, or plasma renin activity. The fall in plasma ANP concentration during treatment correlated with the postural blood pressure drop after dialysis (r=0.505; P<0.05), but was unrelated to changes in weight or plasma renin activity with haemodialysis or haemofiltration. Plasma ANP concentrations rose rapidly again in the 60 min after dialysis treatment, without change in body weight. These results show that high levels of biologically active ANP circulate in end-stage renal disease. The fact that these are not reduced to normal by haemodialysis or haemofiltration, despite restoration to normovolaemic or hypovolaemic state, suggests that the increased levels of ANP in end-stage renal failure are due to both hypervolaemia and other factors, which may include occult cardiac dysfunction and loss of renal clearanc

Cr segregation and impact fracture in a martensitic stainless steel

The fracture surfaces of a 10.5 wt.% Cr martensitic stainless steel broken in Charpy tests have been investigated through X-ray photoelectron spectroscopy (XPS). The specimens have been examined in two different conditions: as-quenched and heat treated for 10 h at 700°C. The trends of Fe/Cr ratio vs. test temperature are similar to the sigmoidal curves of absorbed energy and, after both ductile and quasi-cleavage brittle fractures, such ratio is always significantly lower than the nominal value of the steel chemical composition. Cr segregation does not occur on a macroscopic scale but takes place in microscopic zones which represent weaker spots in the steel matrix and a preferred path for moving cracks. Small area (diameter 300 μm) XPS measurements evidenced a higher density of such microscopic zones in the inner part of probes; this is explained by the different diffusion length of Cr atoms in the external and inner parts during quenching from austenitic field which has been calculated through FEM simulations. No significant differences of Cr concentration were observed in fracture surfaces of probes with and without heat treatment. The results highlight how Cr segregation plays a role not only in the intergranular mode of fracture but also in the quasi-cleavage and ductile ones

Two different acid oxidation syntheses to open C60 fullerene for heavy metal detection

Graphene oxide quantum dots (GOQDs) can be synthesized through a large variety of synthesis methods starting from different carbon allotropes such as nanotubes, graphite, C60 and exploiting various synthesis and reactions. These different approaches have great influence on the properties of the obtained materials, and, consequently, on the potential applications. In this work, Buckminster C60 fullerene has been used to prepare unfolded fullerene nanoparticles (UFNPs) via two distinct synthesis methods namely: Hummer and H2 SO4 + HNO3 solution. The different characteristics of the final materials and the different response in the presence of heavy metal ions have been investigated in view of sensing applications of water contamination

A high temperature superconductor microwave filter working in C-band for the Sardinia Radio Telescope

The interference generated by radio signals of human origin negatively affects the quality of astronomical data and hence the performance of the radio antennae. In this contribution we describe a microwave band-pass filter, created using microstrip planar technology on high temperature superconductor material, for one of the radio astronomical receivers of the Sardinia Radio Telescope. The experimental results obtained at cryogenic temperatures display very low ohmic losses, excellent consistency with the simulations and good repeatability among the various prototypes.Le interferenze generate dai segnali radio antropici limitano la qualità delle osservazioni astronomiche e quindi le prestazioni delle antenne radio. In questo contributo si descrive un filtro passa-banda a microonde realizzato su tecnologia planare in microstriscia su materiale superconduttore ad alta temperatura per uno dei ricevitori radio astronomici del Sardinia Radio Telescope. I risultati sperimentali ottenuti a temperature criogeniche mostrano bassissime perdite ohmiche, un ottimo accordo con le simulazioni ed una buona ripetibilità tra i vari prototipi

Ferrous Campylobacter jejuni truncated hemoglobin P displays an extremely high reactivity for cyanide - A comparative study

Campylobacter jejuni hosts two hemoglobins (Hbs). The Camplylobacter jejuni single-domain Hb (called Cgb) is homologous to the globin domain of flavohemoglobin, and it has been proposed to protect the bacterium against nitrosative stress. The second Hb is called Ctb (hereafter Cj-trHbP), belongs to truncated Hb group III, and has been hypothesized to be involved in O 2 chemistry. Here, the kinetics and thermodynamics of cyanide binding to ferric and ferrous Cj-trHbP [Cj-trHbP(III) and Cj-trHbP(II), respectively] are reported and analyzed in parallel with those of related heme proteins, with particular reference to those from Mycobacterium tuberculosis. The affinity of cyanide for Cj-trHbP(II) is higher than that reported for any known (in)vertebrate globin by more than three orders of magnitude (K = 1.2 × 10-6 m). This can be fully attributed to the highest (ever observed for a ferrous Hb) cyanide-binding association rate constant (kon = 3.3 × 103 m-1·s-1), even though the binding process displays a rate-limiting step (kmax = 9.1 s -1). Cj-trHbP(III) shows a very high affinity for cyanide (L = 5.8 × 10-9 m); however, cyanide association kinetics are independent of cyanide concentration, displaying a rate-limiting step (l max = 2.0 × 10-3 s-1). Values of the first-order rate constant for cyanide dissociation from Cj-trHbP(II)-cyanide and Cj-trHbP(III)-cyanide (koff =5.0 × 10-3 s -1 and loff ≥ 1 × 10-4 s-1, respectively) are similar to those reported for (in)vertebrate globins. The very high affinity of cyanide for Cj-trHbP(II), reminiscent of that of horseradish peroxidase(II), suggests that this globin may participate in cyanide detoxification. © 2008 The Authors

Antenna beam characterisation for the global 21cm experiment LEDA and its impact on signal model parameter reconstruction

Cosmic Dawn, the onset of star formation in the early universe, can in principle be studied via the 21cm transition of neutral hydrogen, for which a sky-averaged absorption signal, redshifted to MHz frequencies, is predicted to be {\it O}(10-100)\,mK. Detection requires separation of the 21cm signal from bright chromatic foreground emission due to Galactic structure, and the characterisation of how it couples to instrumental response. In this work, we present characterisation of antenna gain patterns for the Large-aperture Experiment to detect the Dark Ages (LEDA) via simulations, assessing the effects of the antenna ground-plane geometries used, and measured soil properties. We then investigate the impact of beam pattern uncertainties on the reconstruction of a Gaussian absorption feature. Assuming the pattern is known and correcting for the chromaticity of the instrument, the foregrounds can be modelled with a log-polynomial, and the 21cm signal identified with high accuracy. However, uncertainties on the soil properties lead to \textperthousand\ changes in the chromaticity that can bias the signal recovery. The bias can be up to a factor of two in amplitude and up to few \% in the frequency location. These effects do not appear to be mitigated by larger ground planes, conversely gain patterns with larger ground planes exhibit more complex frequency structure, significantly compromising the parameter reconstruction. Our results, consistent with findings from other antenna design studies, emphasise the importance of chromatic response and suggest caution in assuming log-polynomial foreground models in global signal experiments.Comment: Accepted for publication in MNRA

One-year sustained glycaemic control and less hypoglycaemia with new insulin glargine 300 U/ml compared with 100 U/ml in people with type 2 diabetes using basal plus meal-time insulin : the EDITION 1 12-month randomized trial, including 6-month extension

AimsTo evaluate the maintenance of efficacy and safety of insulin glargine 300 U/ml (Gla-300) versus glargine 100 U/ml (Gla-100) in people with type 2 diabetes mellitus (T2DM) using basal plus meal-time insulin for 12 months in the EDITION 1 trial. MethodsEDITION 1 was a multicentre, randomized, open-label, two-arm, phase IIIa study. Participants completing the initial 6-month treatment period continued to receive Gla-300 or Gla-100, as previously randomized, once daily for a further 6-month open-label extension phase. Changes in glycated haemoglobin (HbA1c) and fasting plasma glucose concentrations, insulin dose, hypoglycaemic events and body weight were assessed. ResultsOf 807 participants enrolled in the initial phase, 89% (359/404) assigned to Gla-300 and 88% (355/403) assigned to Gla-100 completed 12 months. Glycaemic control was sustained in both groups (mean HbA1c: Gla-300, 7.24%; Gla-100, 7.42%), with more sustained HbA1c reduction for Gla-300 at 12 months: least squares mean difference Gla-300 vs Gla-100: HbA1c -0.17 [95% confidence interval (CI) -0.30 to -0.05]%. The mean daily basal insulin dose at 12 months was 1.03 U/kg for Gla-300 and 0.90 U/kg for Gla-100. Lower percentages of participants had 1 confirmed [3.9 mmol/l (70 mg/dl)] or severe hypoglycaemic event with Gla-300 than Gla-100 at any time of day [24 h; 86 vs 92%; relative risk 0.94 (95% CI 0.89-0.99)] and during the night [54 vs 65%; relative risk 0.84 (95% CI 0.75-0.94)], while the annualized rates of such hypoglycaemic events were similar. No between-treatment differences in adverse events were apparent. ConclusionDuring 12 months of treatment of T2DM requiring basal and meal-time insulin, glycaemic control was better sustained and fewer individuals reported hypoglycaemia with Gla-300 than with Gla-100. The mean basal insulin dose was higher with Gla-300 compared with Gla-100, but total numbers of hypoglycaemic events and overall tolerability did not differ between treatments.Peer reviewe

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