Characterizing the optical response of ultra-low-noise far-infrared 60-110 μm transition edge sensors.

Far-infrared Transition Edge Sensors (TESs) are being developed for the SAFARI grating spectrometer on the cooled-aperture space telescope SPICA. In support of this work, we have devised a cryogenic (90 mK) test facility for carrying out precision optical measurements on ultra-low-noise TESs. Although our facility is suitable for the whole of the SAFARI wavelength range, 34 µm-230 µm, we focus on a representative set of measurements at 60 µm-110 µm using a device having a noise equivalent power of 0.

Evidence of a nonequilibrium distribution of quasiparticles in the microwave response of a superconducting aluminum resonator.

In a superconductor, absorption of photons with an energy below the superconducting gap leads to redistribution of quasiparticles over energy and thus induces a strong nonequilibrium quasiparticle energy distribution. We have measured the electrodynamic response, quality factor, and resonant frequency of a superconducting aluminium microwave resonator as a function of microwave power and temperature. Below 200 mK, both the quality factor and resonant frequency decrease with increasing microwave power, consistent with the creation of excess quasiparticles due to microwave absorption.

Second-trimester Down's syndrome serum screening: double, triple or quadruple marker testing?

Background: The recommendations of the UK National Screening Committee (NSC) are based on the findings of the Serum, Urine and Ultrasound Screening Study (SURUSS). Our study sought to establish if the SURUSS findings, in terms of detection rates (DR) and false-positive rates (FPR) for various second-trimester marker combinations, could be replicated in a local setting.

Methods: We investigated the effects of adding inhibin-A and unconjugated oestriol to our existing double test protocol.

Subclinical hypothyroidism: a comparison of strategies to achieve adherence to treatment guidelines.

Background: Subclinical hypothyroidism is an entity based on the laboratory findings of a raised serum thyrotrophin (TSH) concentration and a normal free thyroxine (FT(4)) concentration. Patients with subclinical hypothyroidism who also have anti-thyroid peroxidase (TPO) antibodies have a higher conversion to overt hypothyroidism than those without, and treatment with thyroxine is recommended.

Method: We audited anti-TPO assay requests within two NHS Trust hospitals, against consensus standards, to ascertain whether a cascade approach to anti-TPO testing and direct advice leads to more appropriate prescribing of thyroxine in general practice.

Mechanisms of activation of phosphoenolpyruvate carboxykinase from Escherichia coli by Ca2+ and of desensitization by trypsin.

The 1.8-A resolution structure of the ATP-Mg(2+)-Ca(2+)-pyruvate quinary complex of Escherichia coli phosphoenolpyruvate carboxykinase (PCK) is isomorphous to the published complex ATP-Mg(2+)-Mn(2+)-pyruvate-PCK, except for the Ca(2+) and Mn(2+) binding sites. Ca(2+) was formerly implicated as a possible allosteric regulator of PCK, binding at the active site and at a surface activating site (Glu508 and Glu511).