Method and apparatus for reducing microwave oscillator output noise

Microwave oscilltors incorporate r.f. feedback with carrier suppression to reduce phase noise. In a direct feedback oscillator arrngement a circulator is interposed between the r.f. amplifier and the high-Q resonator. The amplifier output is applied to the slightly over-coupled input port of the resonator so that the resultant net return signal is the vectorial difference between the signals emitted and reflected from the resonator. The gain of the r.f. amplifier is chosen to regenerate the forward signal from the net return signal. In a STALO-type arrangement, the resonator is critically coupled and an r.f. amplifier added to the path of the net return signal. The sensitivity of the STALO-type feedback loop is thereby enhanced while added amplifier noise is minimized by the superposition of the signals emitted by and reflected from the resonator

The new a-theory of time

The New A-theory of Time (TNAT) is the view, to be elaborated and defended in this article, that many times exist, and that time is real in virtue of every moment in time bearing each of the so-called A-properties: past, present and future. I argue that TNAT is at least as theoretically virtuous as mainstream views in the philosophy of time and may have some claim to being our best theory of time. I show that the properties ‘past’, ‘present’ and ‘future’ can be understood as compatible intrinsic properties. Having demonstrated that this account of the A-properties is coherent, I go on to demonstrate how TNAT can give us an account of passage, change and the truth-conditions for temporal sentences. In the final section of the article, I develop a tentative argument in favour of TNAT, though concede that we have to settle for the result that TNAT is on a par with our other theories of time. In the remainder of this opening section, my aim is to situate the current proposal as a direct response to McTaggart’s infamous argument against the reality of time

Phenotype to genotype using forward-genetic Mu-seq for identification and functional classification of maize mutants

In pursuing our long-term goals of identifying causal genes for mutant phenotypes in maize, we have developed a new, phenotype-to-genotype approach for transposon-based resources, and used this to identify candidate genes that co-segregate with visible kernel mutants. The strategy incorporates a redesigned Mu-seq protocol (sequence-based, transposon mapping) for high-throughput identification of individual plants carrying Mu insertions. Forward-genetic Mu-seq also involves a genetic pipeline for generating families that segregate for mutants of interest, and grid designs for concurrent analysis of genotypes in multiple families. Critically, this approach not only eliminates gene-specific PCR genotyping, but also profiles all Mu-insertions in hundreds of individuals simultaneously. Here, we employ this scalable approach to study 12 families that showed Mendelian segregation of visible seed mutants. These families were analyzed in parallel, and 7 showed clear co-segregation between the selected phenotype and a Mu insertion in a specific gene. Results were confirmed by PCR. Mutant genes that associated with kernel phenotypes include those encoding: a new allele of Whirly1 (a transcription factor with high affinity for organellar and single-stranded DNA), a predicted splicing factor with a KH domain, a small protein with unknown function, a putative mitochondrial transcription-termination factor, and three proteins with pentatricopeptide repeat domains (predicted mitochondrial). Identification of such associations allows mutants to be prioritized for subsequent research based on their functional annotations. Forward-genetic Mu-seq also allows a systematic dissection of mutant classes with similar phenotypes. In the present work, a high proportion of kernel phenotypes were associated with mutations affecting organellar gene transcription and processing, highlighting the importance and non-redundance of genes controlling these aspects of seed development

Reasons why people do not attend NHS Health Checks: a systematic review and qualitative synthesis

Background The NHS Health Check programme is a prevention initiative offering cardiovascular risk assessment and management advice to adults aged 40–74 years across England. Its effectiveness depends on uptake. When it was introduced in 2009, it was anticipated that all those eligible would be invited over a 5-year cycle and 75% of those invited would attend. So far in the current cycle from 2013 to 2018, 33.8% of those eligible have attended, which is equal to 48.5% of those invited to attend. Understanding the reasons why some people do not attend is important to maximise the impact of the programmes. Aim To review why people do not attend NHS Health Checks. Design and setting A systematic review and thematic synthesis of qualitative studies. Method An electronic literature search was carried out of MEDLINE, Embase, Health Management Information Consortium, Cumulative Index to Nursing and Allied Health Literature, Global Health, PsycINFO, Web of Science, OpenGrey, the Cochrane Library, NHS Evidence, Google Scholar, Google, ClinicalTrials.gov, and the ISRCTN registry from 1 January 1996 to 9 November 2016, and the reference lists of all included papers were also screened manually. Inclusion criteria were primary research studies that reported the views of people who were eligible for but had not attended an NHS Health Check. Results Nine studies met the inclusion criteria. Reasons for not attending included lack of awareness or knowledge, misunderstanding the purpose of the NHS Health Check, aversion to preventive medicine, time constraints, difficulties with access to general practices, and doubts regarding pharmacies as appropriate settings. Conclusion The findings particularly highlight the need for improved communication and publicity around the purpose of the NHS Health Check programme and the personal health benefits of risk factor detection.This work was funded by a grant from Public Health England. Juliet A Usher-Smith was funded by a National Institute for Health Research (NIHR) Clinical Lectureship and Fiona M Walter by an NIHR Clinician Scientist award (RG 68235). The views expressed in this publication are those of the authors and not necessarily those of the NHS, the NIHR, or the Department of Health. All researchers were independent of the funding body and the funder had no role in data collection, analysis and interpretation of data; in the writing of the report; or decision to submit the article for publication

Bayesian modelling of clusters of galaxies from multi-frequency pointed Sunyaev--Zel'dovich observations

We present a Bayesian approach to modelling galaxy clusters using multi-frequency pointed observations from telescopes that exploit the Sunyaev--Zel'dovich effect. We use the recently developed MultiNest technique (Feroz, Hobson & Bridges, 2008) to explore the high-dimensional parameter spaces and also to calculate the Bayesian evidence. This permits robust parameter estimation as well as model comparison. Tests on simulated Arcminute Microkelvin Imager observations of a cluster, in the presence of primary CMB signal, radio point sources (detected as well as an unresolved background) and receiver noise, show that our algorithm is able to analyse jointly the data from six frequency channels, sample the posterior space of the model and calculate the Bayesian evidence very efficiently on a single processor. We also illustrate the robustness of our detection process by applying it to a field with radio sources and primordial CMB but no cluster, and show that indeed no cluster is identified. The extension of our methodology to the detection and modelling of multiple clusters in multi-frequency SZ survey data will be described in a future work.Comment: 12 pages, 7 figures, submitted to MNRA

High resolution AMI Large Array imaging of spinning dust sources: spatially correlated 8 micron emission and evidence of a stellar wind in L675

We present 25 arcsecond resolution radio images of five Lynds Dark Nebulae (L675, L944, L1103, L1111 & L1246) at 16 GHz made with the Arcminute Microkelvin Imager (AMI) Large Array. These objects were previously observed with the AMI Small Array to have an excess of emission at microwave frequencies relative to lower frequency radio data. In L675 we find a flat spectrum compact radio counterpart to the 850 micron emission seen with SCUBA and suggest that it is cm-wave emission from a previously unknown deeply embedded young protostar. In the case of L1246 the cm-wave emission is spatially correlated with 8 micron emission seen with Spitzer. Since the MIR emission is present only in Spitzer band 4 we suggest that it arises from a population of PAH molecules, which also give rise to the cm-wave emission through spinning dust emission.Comment: accepted MNRA

Microwave observations of spinning dust emission in NGC6946

We report new cm-wave measurements at five frequencies between 15 and 18GHz of the continuum emission from the reportedly anomalous "region 4" of the nearby galaxy NGC6946. We find that the emission in this frequency range is significantly in excess of that measured at 8.5GHz, but has a spectrum from 15-18GHz consistent with optically thin free-free emission from a compact HII region. In combination with previously published data we fit four emission models containing different continuum components using the Bayesian spectrum analysis package radiospec. These fits show that, in combination with data at other frequencies, a model with a spinning dust component is slightly preferred to those that possess better-established emission mechanisms.Comment: submitted MNRA

Cost analysis and outcomes of endoscopic, minimal access and open pancreatic necrosectomy.

To assess both individual patient and institutional costs as well as outcomes in patients with pancreatic necrosis who underwent either endoscopic, minimal access or open pancreatic necrosectomy. These data can be used to evaluate clinical effectiveness with a view to informing local health care providers. Intervention for infected pancreatic necrosis is associated with a high morbidity, mortality and long hospital stays. Minimal access surgical step-up approaches have been the gold standard of care, however endoscopic approaches are now offered preferentially. All patients undergoing endoscopic (EN), minimal access retroperitoneal (MARPN) and open (OPN) necrosectomy at a single institution from April 2015-March 2017 were included. Patients were selected for intervention based on morphology and position of the necrosis and on clinical factors. Patient level costing systems were used to determine inpatient and outpatient costs. 86 patients were included: 38 underwent EN, 35 MARPN and 13 OPN. Pre-operative APACHEII was 6 vs 9 vs 9 (p=0.017) and CRP 107 vs 204 vs 278, (p=0.012), respectively. Post-operative stay was 19 days for EN vs. 41 for MARPN vs. 42 for OPN (p=0.007). Complications occurred in 68.4%, 68.6% and 46.2% (p=0.298) while mortality was 10.5%, 22.9% and 15.4% (p=0.379) respectively. Mean total cost was £31,364 for EN, £52,770 for MARPN (p=0.008) and £60,346 for OPN. Ward and critical care costs for EN were lower than for MARPN (ward: £9,430 vs. £14,033, p=0.024; critical care: £5,317 vs. £16,648, p=0.056)

AMI observations of Lynds Dark Nebulae: further evidence for anomalous cm-wave emission

Observations at 14.2 to 17.9 GHz made with the AMI Small Array towards fourteen Lynds Dark Nebulae with a resolution of 2' are reported. These sources are selected from the SCUBA observations of Visser et al. (2001) as small angular diameter clouds well matched to the synthesized beam of the AMI Small Array. Comparison of the AMI observations with radio observations at lower frequencies with matched uv-plane coverage is made, in order to search for any anomalous excess emission which can be attributed to spinning dust. Possible emission from spinning dust is identified as a source within a 2' radius of the Scuba position of the Lynds dark nebula, exhibiting an excess with respect to lower frequency radio emission. We find five sources which show a possible spinning dust component in their spectra. These sources have rising spectral indices in the frequency range 14.2--17.9 GHz. Of these five one has already been reported, L1111, we report one new definite detection, L675, and three new probable detections (L944, L1103 and L1246). The relative certainty of these detections is assessed on the basis of three criteria: the extent of the emission, the coincidence of the emission with the Scuba position and the likelihood of alternative explanations for the excess. Extended microwave emission makes the likelihood of the anomalous emission arising as a consequence of a radio counterpart to a protostar or a proto-planetary disk unlikely. We use a 2' radius in order to be consistent with the IRAS identifications of dark nebulae (Parker 1988), and our third criterion is used in the case of L1103 where a high flux density at 850 microns relative to the FIR data suggests a more complicated emission spectrum.Comment: submitted MNRA

Quantification of Silent Cerebral Infarction on High-Resolution FLAIR and Cognition in Sickle Cell Anemia

Research in sickle cell anemia (SCA) has used, with limited race-matched control data, binary categorization of patients according to the presence or absence of silent cerebral infarction (SCI). SCI have primarily been identified using low-resolution MRI, with radiological definitions varying in lesion length and the requirement for abnormality on both fluid attenuated inversion recovery (FLAIR) and T1-weighted images. We aimed to assess the effect of published SCI definitions on global, regional, and lobar lesion metrics and their value in predicting cognition. One hundred and six patients with SCA and 48 controls aged 8-30 years underwent 3T MRI with a high-resolution FLAIR sequence and Wechsler cognitive assessment. Prevalence, number, and volume of lesions were calculated using a semi-automated pipeline for SCI defined as: (1) Liberal: any length (L-SCI); (2) Traditional: >3 mm in greatest dimension (T-SCI); (3) Restrictive; >3 mm in greatest dimension with a corresponding T1-weighted hypo-intensity (R-SCI). Globally, as hypothesized, there were large effects of SCI definition on lesion metrics in patients and controls, with prevalence varying from 24-42% in patients, and 4-23% in controls. However, contrary to hypotheses, there was no effect of any global metric on cognition. Regionally, there was a consistent distribution of SCI in frontal and parietal deep and juxta-cortical regions across definitions and metrics in patients, but no consistent distribution in controls. Effects of regional SCI metrics on cognitive performance were of small magnitude; some were paradoxical. These findings expose the challenges associated with the widespread use of SCI presence as a biomarker of white-matter injury and cognitive dysfunction in cross-sectional high-resolution MRI studies in patients with SCA. The findings indicate that with high-resolution MRI: (1) radiological definitions have a large effect on resulting lesion groups, numbers, and volumes; (2) there is a non-negligible prevalence of lesions in young healthy controls; and (3) at the group-level, there is no cross-sectional association between global lesion metrics and general cognitive impairment irrespective of lesion definition and metric. With high-resolution multi-modal MRI, the dichotomy of presence or absence of SCI does not appear to be a sensitive biomarker for the detection of functionally significant pathology; the search for appropriate endpoints for clinical treatment trials should continue