Effect of an electric field on superfluid helium scintillation produced by alpha-particle sources

We report a study of the intensity and time dependence of scintillation produced by weak alpha particle sources in superfluid helium in the presence of an electric field (0 - 45 kV/cm) in the temperature range of 0.2 K to 1.1 K at the saturated vapor pressure. Both the prompt and the delayed components of the scintillation exhibit a reduction in intensity with the application of an electric field. The reduction in the intensity of the prompt component is well approximated by a linear dependence on the electric field strength with a reduction of 15% at 45 kV/cm. When analyzed using the Kramers theory of columnar recombination, this electric field dependence leads to the conclusion that roughly 40% of the scintillation results from species formed from atoms originally promoted to excited states and 60% from excimers created by ionization and subsequent recombination with the charges initially having a cylindrical Gaussian distribution about the alpha track of 60 nm radius. The intensity of the delayed component of the scintillation has a stronger dependence on the electric field strength and on temperature. The implications of these data on the mechanisms affecting scintillation in liquid helium are discussed.Comment: 17 pages, 23 figure

A strained silicon cold electron bolometer using Schottky contacts

We describe optical characterisation of a strained silicon cold electron bolometer (CEB), operating on a 350 mK stage, designed for absorption of millimetre-wave radiation. The silicon cold electron bolometer utilises Schottky contacts between a superconductor and an n++ doped silicon island to detect changes in the temperature of the charge carriers in the silicon, due to variations in absorbed radiation. By using strained silicon as the absorber, we decrease the electron-phonon coupling in the device and increase the responsivity to incoming power. The strained silicon absorber is coupled to a planar aluminium twin-slot antenna designed to couple to 160 GHz and that serves as the superconducting contacts. From the measured optical responsivity and spectral response, we calculate a maximum optical efficiency of 50% for radiation coupled into the device by the planar antenna and an overall noise equivalent power, referred to absorbed optical power, of 1.1×10−16 W Hz−1/2 when the detector is observing a 300 K source through a 4 K throughput limiting aperture. Even though this optical system is not optimized, we measure a system noise equivalent temperature difference of 6 mK Hz−1/2. We measure the noise of the device using a cross-correlation of time stream data, measured simultaneously with two junction field-effect transistor amplifiers, with a base correlated noise level of 300 pV Hz−1/2 and find that the total noise is consistent with a combination of photon noise, current shot noise, and electron-phonon thermal noise

Water-gated organic nanowire transistors

We gated both p-type, and n-type, organic nanowire (NW) films with an aqueous electric double layer (EDL) in thin-film transistor (TFT) architectures. For p-type NWs, we used poly(3-hexylthiophene) (P3HT) NWs grown via two different routes. Both can be gated with water, resulting in TFTs with threshold lower than for conventionally cast P3HT films under the same gating conditions. However, TFT drain currents are lower for NWs than for conventional P3HT films, which agrees with similar observations for ‘dry’ gated TFTs. For n-type NWs, we have grown ‘nanobelts’ of poly(benzimidazobenzophenanthroline) (BBL) by a solvent/non-solvent mixing route with later displacement of the solvent, and dispersion in a non-solvent. Water-gating such films initially failed to give an observable drain current. However, BBL nanobelts can be gated with the aprotic solvent acetonitrile, giving high n-type drain currents, which are further increased by adding salt. Remarkably, after first gating BBL NW films with acetonitrile, they can then be gated by water, giving very high drain currents. This behaviour is transient on a timescale of minutes. We believe this observation is caused by a thin protective acetonitrile film remaining on the nanobelt surface

Technological capabilities to assess digital excellence in hospitals in high performing healthcare systems::an international eDelphi exercise

Background: Hospitals worldwide are developing ambitious digital transformation programs as part of broader efforts to create digitally advanced health care systems. However, there is as yet no consensus on how best to characterize and assess digital excellence in hospitals. Objective: Our aim was to develop an international agreement on a defined set of technological capabilities to assess digital excellence in hospitals. Methods: We conducted a two-stage international modified electronic Delphi (eDelphi) consensus-building exercise, which included a qualitative analysis of free-text responses. In total, 31 international health informatics experts participated, representing clinical, academic, public, and vendor organizations. Results: We identified 35 technological capabilities that indicate digital excellence in hospitals. These are divided into two categories: (a) capabilities within a hospital (n=20) and (b) capabilities enabling communication with other parts of the health and social care system, and with patients and carers (n=15). The analysis of free-text responses pointed to the importance of nontechnological aspects of digitally enabled change, including social and organizational factors. Examples included an institutional culture characterized by a willingness to transform established ways of working and openness to risk-taking. The availability of a range of skills within digitization teams, including technological, project management and business expertise, and availability of resources to support hospital staff, were also highlighted. Conclusions: We have identified a set of criteria for assessing digital excellence in hospitals. Our findings highlight the need to broaden the focus from technical functionalities to wider digital transformation capabilities

What is the quality of economic evaluations of non-drug therapies? A systematic review and critical appraisal of economic evaluations of radiotherapy for cancer. Applied Health Economics and Health Policy.

Background Breast, cervical and colorectal cancers are the three most frequent cancers in women, while lung, prostate and colorectal cancers are the most frequent in men. Much attention has been given to the economic evaluation of pharmaceuticals for treatment of cancer by the National Institute for Health and Care Excellence (NICE) in the UK and similar authorities internationally, while economic analysis developed for other types of anti-cancer interventions, including radiotherapy and surgery, are less common. Objectives Our objective was to review methods used in published cost-effectiveness studies evaluating radiotherapy for breast, cervical, colorectal, head and neck and prostate cancer, and to compare the economic evaluation methods applied with those defined in the guidelines used by the NICE technology appraisal programme. Methods A systematic search of seven databases (MEDLINE, EMBASE, CDSR, NHSEED, HTA, DARE, EconLit) as well as research registers, the NICE website and conference proceedings was conducted in July 2012. Only economic evaluations of radiotherapy interventions in individuals diagnosed with cancer that included quality-adjusted life-years (QALYs) or life-years (LYs) were included. Included studies were appraised on the basis of satisfying essential, preferred and UK-specific methods requirements, building on the NICE Reference Case for economic evaluations and on other methods guidelines. Results A total of 29 studies satisfied the inclusion criteria (breast 14, colorectal 2, prostate 10, cervical 0, head and neck 3). Only two studies were conducted in the UK (13 in the USA). Among essential methods criteria, the main issue was that only three (10 %) of the studies used clinical-effectiveness estimates identified through systematic review of the literature. Similarly, only eight (28 %) studies sourced health-related quality-of-life data directly from patients with the condition of interest. Other essential criteria (e.g. clear description of comparators, patient group indication and appropriate time horizon) were generally fulfilled, while most of the UK-specific requirements were not met. Conclusion Based on this review there is a dearth of up-to-date, robust evidence on the cost effectiveness of radiotherapy in cancer suitable to support decision making in the UK. Studies selected did not fully satisfy essential method standards currently recommended by NICE