Measurements of antenna polar diagrams and efficiencies using a phase-switched interferometer

It is desirable to know antenna polar patterns and efficiencies accurately. In the past, calibration measurements have been made using balloons and aircraft and more recently satellites. These techniques are usually very expensive. It is shown that under certain circumstances it is possible to use a simpler and inexpensive technique by connecting together the antenna under test with another antenna to form a phase switched interferometer as first described by Ryle (1952). The technique does require a suitable radio source which gives measurable powers when using small antennas and since dipoles have broad patterns, radio sources with similar right ascensions but different declinations to the primary source can be a problem. These problems can partly be overcome by filtering the interference pattern

Class-D audio amplifiers with negative feedback

There are many different designs for audio amplifiers. Class-D, or switching, amplifiers generate their output signal in the form of a high-frequency square wave of variable duty cycle (ratio of on time to off time). The square-wave nature of the output allows a particularly efficient output stage, with minimal losses. The output is ultimately filtered to remove components of the spectrum above the audio range. Mathematical models are derived here for a variety of related class-D amplifier designs that use negative feedback. These models use an asymptotic expansion in powers of a small parameter related to the ratio of typical audio frequencies to the switching frequency to develop a power series for the output component in the audio spectrum. These models confirm that there is a form of distortion intrinsic to such amplifier designs. The models also explain why two approaches used commercially succeed in largely eliminating this distortion; a new means of overcoming the intrinsic distortion is revealed by the analysis. Copyright (2006) Society for Industrial and Applied Mathematic

The Adelaide VHF radar: Capabilities and future plans

The VHF radar at Buckland Park, South Australia commenced operation in January, 1984. The radar is located adjacent to the 2-MHz ionospheric radar. The routine method for measuring horizontal wind velocity is the space antenna technique (SA) while the Doppler technique is used to measure vertical velocities. It is possible to swing the transmitting beam in the east-west plane, allowing Doppler measurements of the EW wind component

Description of complex interventions: analysis of changes in reporting in randomised trials since 2002

BACKGROUND: Inadequate description of non-pharmacological complex interventions in trial publications means that they cannot be replicated or assessed for generalisability. There are published guidelines on how to describe an intervention, such as those from the CONSORT Group. However, there have been few evaluations of whether intervention reporting is improving. METHODS: We aimed to assess whether descriptions of multicomponent, non-pharmacological interventions evaluated in randomised trials are improving. To do so, we chose trials of educational and psychotherapeutic interventions to promote adherence to therapy, and compared those published between 2002 and 2007 (Time-1) with those between 2010 and 2015 (Time-2). These time periods were chosen to concord with the publication in 2008 of the CONSORT extension statement of reporting guidelines for non-pharmacological treatment which included items on intervention description. We assessed 19 items, based on the CONSORT Statement and the more recent Template for Intervention Description and Replication Checklist (TIDieR). Two reviewers independently extracted data. We created a quality score of the eight items we considered key information for replication and assessment of generalisability (setting, provider, recipient, comparator, intervention intensity, how it was conducted, existence of a manual or protocol, and detail of whether there was an assessment of fidelity). Score per item was '1' if reported adequately and '0' if not. RESULTS: Of the eligible trials, 42 were published in Time-1 and 134 published in Time-2. The trials included were published in 112 peer-reviewed journals, 52 of these journals currently require authors to follow the CONSORT Statements, while only one recommended adherence to the TIDieR. Most items of CONSORT and TIDieR were reported by more than half of the trials at both time points. Few trials reported fidelity. A large proportion of the trials did not report the existence of a manual or protocol, or what the comparator group received. We found no statistically significant improvement in the eight-item quality score (Time-1: mean 5.71 (standard deviation (SD) 1.09), Time-2: 5.87 (SD 1.28), p = 0.49). CONCLUSIONS: We found no overall evidence that reporting the specifics of multicomponent, non-pharmacological interventions is improving. Details to replicate interventions remain lacking, impairing best implementation or meaningful further research. Editorial endorsement of reporting checklists needs to be more extensive

Partial reflections: interactive environments for musical exploration

This paper describes an ongoing project to develop interactive environments for musicians that encourage musical exploration. A process of developing software such as this, where requirements are highly dynamic and unclear is outlined and two musical compositions and associated interactive environments entitled 'Partial Reflections' are described

Does current UK research address priorities in palliative and end-of-life care?

The Palliative and end of life care Priority Setting Partnership uncovered 83 unanswered research questions. Florence Todd Fordham, Bridget Candy, Stevie McMillan and Sabine Best show that, as current UK research starts to address some of these questions, UK open grant data have the potential to encourage collaboratio

Interventions for sexual dysfunction following treatments for cancer in women

BACKGROUND: The proportion of people living with and surviving cancer is growing. This has led to increased awareness of the importance of quality of life, including sexual function, in those affected by cancer. Sexual dysfunction is a potential long-term complication of many cancer treatments. This includes treatments that have a direct impact on the pelvic area and genitals, and also treatments that have a more generalised (systemic) impact on sexual function.This is an update of the original Cochrane review published in Issue 4, 2007, on interventions for treating sexual dysfunction following treatments for cancer for men and women. Since publication in 2007, there has been an increase in the number of trials for both men and women and this current review critiques only those for women. A review in press will present those for men. OBJECTIVES: To evaluate the effectiveness of interventions for treating sexual dysfunction in women following treatments for cancer. To assess adverse events associated with interventions. SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL 2015, Issue 9), MEDLINE, EMBASE, PsycINFO, AMED, CINAHL, Dissertation Abstracts and the NHS Research Register. The searches were originally run in January 2007 and we updated these to September 2015. SELECTION CRITERIA: We included randomised controlled trials (RCTs) that assessed the effectiveness of a treatment for sexual dysfunction. The trial participants were women who had developed sexual dysfunction as a consequence of a cancer treatment. We sought evaluations of interventions that were pharmaceutical, mechanical, psychotherapeutic, complementary or that involved physical exercise. DATA COLLECTION AND ANALYSIS: Two review authors independently extracted the data and assessed trial quality. We considered meta-analysis for trials with comparable key characteristics. MAIN RESULTS: Since the original version of this review we have identified 11 new studies in women. The one study identified in the earlier version of this review was excluded in this update as it did not meet our narrower inclusion criteria to include only interventions for the treatment, not prevention, of sexual dysfunction.In total 1509 female participants were randomised across 11 trials. All trials explored interventions following treatment either for gynaecological or breast cancer. Eight trials evaluated a psychotherapeutic or psycho-educational intervention. Two trials evaluated a pharmaceutical intervention and one pelvic floor exercises. All involved heterosexual women. Eight studies were at a high risk of bias as they involved a sample of fewer than 50 participants per trial arm. The trials varied not only in intervention content but in outcome measurements, thereby restricting combined analysis. In the trials evaluating a psychotherapeutic intervention the effect on sexual dysfunction was mixed; in three trials benefit was found for some measures of sexual function and in five trials no benefit was found. Evidence from the other three trials, two on different pharmaceutical applications and one on exercise, differed and was limited by small sample sizes. Only the trial of a pH-balanced vaginal gel found significant improvements in sexual function. The trials of pharmaceutical interventions measured harm: neither reported any. Only one psychological intervention trial reported that no harm occurred because of the intervention; the other trials of psychological support did not measure harm. AUTHORS' CONCLUSIONS: Since the last version of this review, the new studies do not provide clear information on the impact of interventions for sexual dysfunction following treatments for cancer in women. The sexual dysfunction interventions in this review are not representative of the range that is available for women, or of the wider range of cancers in which treatments are known to increase the risk of sexual problems. Further evaluations are needed

The under reporting of recruitment strategies in research with children with life threatening illnesses: A systematic review

BACKGROUND: Researchers report difficulties in conducting research with children and young people (CYP) with life-limiting conditions (LLC) or life-threatening illnesses (LTI) and their families. Recruitment is challenged by barriers including ethical, logistical and clinical considerations. AIM: To explore how children and young people (aged 0-25 years) with life-limiting conditions or life-threatening illnesses and their families were identified, invited and consented to research published in the last 5 years. DESIGN: Systematic review. DATA SOURCES: Medline, PsycINFO, Web of Science, Sciences Citation Index, SCOPUS were searched for original English language research published between 2009-2014, recruiting children and young people with life-limiting conditions or life-threatening illness and their families. RESULTS: Two-hundred and fifteen studies; 152 qualitative, 54 quantitative, 9 mixed methods were included. Limited recruitment information but a range of strategies and difficulties were provided. The proportion of eligible participants from those screened could not be calculated in 80% of studies. Recruitment rates could not be calculated in 77%. Thirty-one per cent of studies recruited less than 50% of eligible participants. Reasons given for non-invitation included missing clinical or contact data, or clinician judgements of participant unsuitability. Reasons for non-participation included lack of interest and participants’ perceptions of potential burdens. CONCLUSIONS: All stages of recruitment were under reported. Transparency in reporting of participant identification, invitation and consent is needed to enable researchers to understand research implications, bias risk and to whom results apply. Research is needed to explore why consenting participants decide to take part or not and their experiences of research recruitment