Oscillatory and Transient Phenomena in Dynamo Circuits

It has been indicated by mathematical analysis and proved, in some cases, by experiment that: (1) A dynamo, the field of which is excited through a transformer, will produce and maintain low frequency oscillations of controllable magnitude and frequency. (2) A shunt wound dynamo, having a mutual inductive link between the load and field circuits will self-excite, produce, and maintain low frequency oscillations of controllable amplitude and frequency. (3) A plain shunt dynamo, although capable of oscillatory discharge, will not maintain oscillations without external aid. (4) A plain series dynamo can neither produce an oscillatory discharge nor maintain oscillations without external aid. (5) In a compound dynamo the fields of which are mutually linked, the tendency to maintain oscillations through the presence of mutual inductance is balanced, or partially balanced, by the impulse from the series winding. (6) In a compound dynamo the fields of which are not mutually linked, the tendency to produce and maintain oscillations is present due to the impulse from the series winding. Analysis indicates that this impulse must be positive, that is, obtained from cumulative series coils, and in Chapter 6, would appear that a further condition is necessary for the maintenance of oscillations. This is that although the dynamo is cumulatively wound, the field must fall with increase of load current. (7) A separately excited dynamo can produce and maintain oscillations if either the transformer or series impulse method is correctly applied. In testing the above statements 6 generators of various types and sizes were examined, some of these having completely laminated field structures and compensating windings, others with salient poles and solid yokes, and one having neither compensating nor interpole windings. These generators varied in output from 6 to 320 Kw, in speed from 1000 to 3000 r. p. m. and all have been known or caused (for the purpose of this investigation) to self-excite, produce and maintain low frequency oscillations under various conditions of excitation. These results indicate that any shunt dynamo-electric machine may self-excite under suitable conditions and that there exists a value of M which can be inserted between the load and field circuits to cause this condition, For the compound wound dynamo it will not be so easy to arrange for an oscillatory condition because of the difficulty of providing a series winding without interfering with the shunt winding and at the same time assuring that the dynamo is naturally capable of oscillatory discharge. It has been further indicated by theory and proved in some cases, by experiment, that: (a) The linear theory, under the quoted assumptions, gives reasonably good results for the Chapter 6. transient values of current and voltage during switching. (b) The linear equation, although giving a good indication that maintained oscillations may be expected under certain conditions, does not correctly predict either the wave shape or the frequency of the resulting oscillation. (c) To obtain rapid response to sudden changes of load it is necessary that the magnetic energy stored in the armature and field circuits must be kept as low, and that in the load circuit relatively as high as possible. (d) For extreme rapidity of response in larger dynamos, the use of high ceiling voltage exciters and injector transformers are indicated. Concluding, the oscillograms taken from the three welding dynamos of recent but quite different design, indicate that the criteria evolved for good welding performance are reasonable

Designing for Safety:Implications of a Fifteen Year Review of Swallowed and Aspirated Dentures

Objectives: Dentures are worn by around 20% of the population, yet if they become displaced they may enter the gastrointestinal or respiratory system, sometimes with grave consequences. The aim of this study was to review recent published literature in order to identify the epidemiology of patients and characteristics of swallowed and aspirated dental prostheses, and propose strategies to minimise these risks. Material and Methods: A fifteen year retrospective of published case series and case reports was carried out. Photographs, radiographs and descriptions of the dental prostheses were gathered, as well as the patient’s presenting complaint, the anatomical site where the denture was caught and the procedure required to remove the denture. Results: Ninety one separate events of swallowed or aspirated dentures were identified from 83 case reports and series from 28 countries. Average age was 55 years, and these were 74% male. Photographs were retrieved for 49 of these dentures. Clasps were present in 25 of the dentures. There was no significant difference between clasped and unclasped dentures for perforation rates, need for open surgery and spontaneously passed dentures. Conclusions: We discuss the implications of this study regarding denture designs, specifically the importance of using a radiopaque acrylic, using clasps when required even if there is a risk of aspiration, advising patients to return if a denture is loose or damaged, and finally that all patients who wear a denture are at risk of aspiration and swallowing events, and associated morbidity and mortality

Causes of prehospital misinterpretations of ST elevation myocardial infarction

Objectives: To determine the causes of software misinterpretation of ST elevation myocardial infarction (STEMI) compared to clinically identified STEMI to identify opportunities to improve prehospital STEMI identification. Methods: We compared ECGs acquired from July 2011 through June 2012 using the LIFEPAK 15 on adult patients transported by the Los Angeles Fire Department. Cases included patients ≥18 years who received a prehospital ECG. Software interpretation of the ECG (STEMI or not) was compared with data in the regional EMS registry to classify the interpretation as true positive (TP), true negative (TN), false positive (FP), or false negative (FN). For cases where classification was not possible using registry data, 3 blinded cardiologists interpreted the ECG. Each discordance was subsequently reviewed to determine the likely cause of misclassification. The cardiologists independently reviewed a sample of these discordant ECGs and the causes of misclassification were updated in an iterative fashion. Results: Of 44,611 cases, 50% were male (median age 65; inter-quartile range 52–80). Cases were classified as 482 (1.1%) TP, 711 (1.6%) FP, 43371 (97.2%) TN, and 47 (0.11%) FN. Of the 711 classified as FP, 126 (18%) were considered appropriate for, though did not undergo, emergent coronary angiography, because the ECG showed definite (52 cases) or borderline (65 cases) ischemic ST elevation, a STEMI equivalent (5 cases) or ST-elevation due to vasospasm (4 cases). The sensitivity was 92.8% [95% CI 90.6, 94.7%] and the specificity 98.7% [95% CI 98.6, 98.8%]. The leading causes of FP were ECG artifact (20%), early repolarization (16%), probable pericarditis/myocarditis (13%), indeterminate (12%), left ventricular hypertrophy (8%), and right bundle branch block (5%). There were 18 additional reasons for FP interpretation (<4% each). The leading causes of FN were borderline ST-segment elevations less than the algorithm threshold (40%) and tall T waves reducing the ST/T ratio below threshold (15%). There were 11 additional reasons for FN interpretation occurring ≤3 times each. Conclusion: The leading causes of FP automated interpretation of STEMI were ECG artifact and non-ischemic causes of ST-segment elevation. FN were rare and were related to ST-segment elevation or ST/T ratio that did not meet the software algorithm threshold

Normative Alethic Pluralism

Some philosophers have argued that truth is a norm of judgement and have provided a variety of formulations of this general thesis. In this paper, I shall side with these philosophers and assume that truth is a norm of judgement. What I am primarily interested in here are two core questions concerning the judgement-truth norm: (i) what are the normative relationships between truth and judgement? And (ii) do these relationships vary or are they constant? I argue for a pluralist picture—what I call Normative Alethic Pluralism (NAP)—according to which (i) there is more than one correct judgement-truth norm and (ii) the normative relationships between truth and judgement vary in relation to the subject matter of the judgement. By means of a comparative analysis of disagreement in three areas of the evaluative domain—refined aesthetics, basic taste and morality—I show that there is an important variability in the normative significance of disagreement—I call this the variability conjecture. By presenting a variation of Lynch’s scope problem for alethic monism, I argue that a monistic approach to the normative function of truth is unable to vindicate the conjecture. I then argue that normative alethic pluralism provides us with a promising model to account for it

Leptin Predicts Diabetes but Not Cardiovascular Disease: Results from a large prospective study in an elderly population

OBJECTIVE—To clarify the association of circulating levels of leptin with risk for cardiovascular disease (CVD) events and new-onset diabetes in men and women

Unraveling the directional link between adiposity and inflammation: a bidirectional mendelian randomization approach

<b>Context</b>: Associations between adiposity and circulating inflammation markers are assumed to be causal, although the direction of the relationship has not been proven. <b>Objective</b>: The aim of the study was to explore the causal direction of the relationship between adiposity and inflammation using a bidirectional Mendelian randomization approach. <b>Methods</b>: In the PROSPER study of 5804 elderly patients, we related C-reactive protein (CRP) single nucleotide polymorphisms (SNPs) (rs1800947 and rs1205) and adiposity SNPs (FTO and MC4R) to body mass index (BMI) as well as circulating levels of CRP and leptin. We gave each individual two allele scores ranging from zero to 4, counting each pair of alleles related to CRP levels or BMI. <b>Results</b>: With increasing CRP allele score, there was a stepwise decrease in CRP levels (P for trend < 0.0001) and a 1.98 mg/liter difference between extremes of the allele score distribution, but there was no associated change in BMI or leptin levels (P ≥ 0.89). By contrast, adiposity allele score was associated with 1) an increase in BMI (1.2 kg/m2 difference between extremes; P for trend 0.002); 2) an increase in circulating leptin (5.77 ng/ml difference between extremes; P for trend 0.0027); and 3) increased CRP levels (1.24 mg/liter difference between extremes; P for trend 0.002). <b>Conclusions</b>: Greater adiposity conferred by FTO and MC4R SNPs led to higher CRP levels, with no evidence for any reverse pathway. Future studies should extend our findings to other circulating inflammatory parameters. This study illustrates the potential power of Mendelian randomization to dissect directions of causality between intercorrelated metabolic factors

Demographic, multi-morbidity and genetic impact on myocardial involvement and its recovery from COVID-19 : protocol design of COVID-HEART-a UK, multicentre, observational study

Acknowledgements CB acknowledges British Heart Foundation support (RE/18/6134217). GPM is funded by a NIHR Research Professorship (RP‐2017‐08‐ST2‐007). CM is funded by a NIHR Clinician Scientist Award (CS‐2015‐15‐003). VMF and SN acknowledge the NIHR Oxford BRC for support of this study. CBD is in part supported by the NIHR Biomedical Research Centre at University Hospitals Bristol NHS Foundation Trust and the University of Bristol. Additional support was provided by the NIHR Leicester Biomedical Research Centre and the NIHR Leeds Clinical Research Facility. The views expressed in this publication are those of the author(s) and not necessarily those of the NHS, the National Institute for Health Research or the Department of Health and Social Care. We thank the patients and staff who have supported this project. Dr. Warren J. Manning served as a Guest Editor for this manuscript. Study Management and Recruitment centres: Grant applicants: JP Greenwood (chief investiga‐ tor), GP McCann, C Berry, M Dweck, J Moon, CM Miller, A Chiribiri, S Prasad, VM Ferreira, C Bucciarelli‐Ducci, D Dawson. Data repository and statistical analysis: Glasgow Clinical Trials Unit. Senior study statistician: Prof A McConnachie, GCTU. Local Principle Investigators and Recruitment Centres: Prof John Green‐ wood, Leeds Teaching Hospitals NHS Trust, UK; Prof Gerry McCann, Glenfield Hospital, Leicester, UK; Prof Dana Dawson, Aberdeen Royal Infirmary, UK; Prof Marc Dweck, Royal Infirmary of Edinburgh, UK; Prof Vanessa Ferreira, JohnRadcliffe Hospital, Oxford, UK; Prof Colin Berry, Queen Elizabeth University Hospital, Glasgow, UK; Dr Peter Swoboda, Pinderfields Hospital, Wakefield, UK; Dr Richard Steeds, Queen Elizabeth Hospital, Birmingham, UK; Prof James Moon, UCL Hospital London, UK; Dr Christopher Miller, Wythenshawe Hospital, Manchester, UK; Dr Timothy Fairbairn, Liverpool Heart and Chest Hospital, UK; Dr Andrew Flett, Southampton General Hospital, UK; Prof Marianna Fontana, Royal Free Hospital, London, UK; Dr Thomas Green, Northumbria NHS Trust, UK; Prof Amedeo Chiribiri, St Thomas’ Hospital, London, UK; Dr Chiara Bucciarelli‐Ducci, University Hospitals Bristol and Weston NHS Trust, UK; Dr Graham Cole, Hammersmith Hospital, London, UK; Prof Sanjay Prasad, Royal Brompton Hospital, London, UK; Dr Adam McDiarmid, Freeman Hospital, New‐ castle Upon Tyne, UK; Dr Nicholas Bunce, St Georges Hospital, London, UK; Dr Prathap Kanagala, Aintree University Hospital, Liverpool, UK; Prof Nicholas Bellenger, The Royal Devon and Exeter Hospital, UK; Dr Tishi Ninan, Swansea Bay University Hospital, UK; Dr Khaled Alfakih, Lewisham University Hospital, London, UK; Prof James Moon, St Bartholomew’s Hospital, London, UK. Funding COVID‐HEART is funded by the National Institute for Health Research (NIHR) and UK Research and Innovation (UKRI) COVID‐19 Rapid Response Rolling Call (Grant Number COV0254), and sponsored by the University of Leeds, UK. The study has been endorsed by the British Society of Cardiovascular Magnetic Resonance (BSCMR) Research Group, and nationally prioritised, and received both BHF‐NIHR Cardiovascular Partnership Flagship Status, and the NIHR Urgent Public Health Group identified it as an Urgent Public Health (UPH) study. Funding for the translation of the patient information leaflets into non‐ English languages was provided by the West Yorkshire and Humber Clinical Research Network (CV070).Peer reviewedPublisher PD

Microscopic calculations of medium effects for 200-MeV (p,p') reactions

We examine the quality of a G-matrix calculation of the effective nucleon-nucleon (NN) interaction for the prediction of the cross section and analyzing power for 200-MeV (p,p') reactions that populate natural parity states in $^{16}$O, $^{28}$Si, and $^{40}$Ca. This calculation is based on a one-boson-exchange model of the free NN force that reproduces NN observables well. The G-matrix includes the effects of Pauli blocking, nuclear binding, and strong relativistic mean-field potentials. The implications of adjustments to the effective mass ansatz to improve the quality of the approximation at momenta above the Fermi level will be discussed, along with the general quality of agreement to a variety of (p,p') transitions.Comment: 36 pages, TeX, 18 figure

Targeting rehabilitation to improve outcomes after total knee arthroplasty in patients at risk of poor outcomes: randomised controlled trial

Objective: To evaluate whether a progressive course of outpatient physiotherapy offers superior outcomes to a single physiotherapy review and home exercise based intervention when targeted at patients with a predicted poor outcome after total knee arthroplasty.Design: Parallel group randomised controlled trial.Setting: 13 secondary and tertiary care centres in the UK providing postoperative physiotherapy.Participants: 334 participants with knee osteoarthritis who were defined as at risk of a poor outcome after total knee arthroplasty, based on the Oxford knee score, at six weeks postoperatively. 163 were allocated to therapist led outpatient rehabilitation and 171 to a home exercise based protocol.Interventions: All participants were reviewed by a physiotherapist and commenced 18 sessions of rehabilitation over six weeks, either as therapist led outpatient rehabilitation (progressive goal oriented functional rehabilitation protocol, modified weekly in one-one contact sessions) or as physiotherapy review followed by a home exercise based regimen (without progressive input from a physiotherapist).Main outcome measures: Primary outcome was Oxford knee score at 52 weeks, with a 4 point difference between groups considered to be clinically meaningful. Secondary outcomes included additional patient reported outcome measures of pain and function at 14, 26, and 52 weeks post-surgery.Results: 334 patients were randomised. Eight were lost to follow-up. Intervention compliance was more than 85%. The between group difference in Oxford knee score at 52 weeks was 1.91 (95% confidence interval ?0.18 to 3.99) points, favouring the outpatient rehabilitation arm (P=0.07). When all time point data were analysed, the between group difference in Oxford knee score was a non-clinically meaningful 2.25 points (0.61 to 3.90, P=0.01). No between group differences were found for secondary outcomes of average pain (0.25 points, ?0.78 to 0.28, P=0.36) or worst pain (0.22 points, ?0.71 to 0.41, P=0.50) at 52 weeks or earlier time points, or of satisfaction with outcome (odds ratio 1.07, 95% confidence interval 0.71 to 1.62, P=0.75) or post-intervention function (4.64 seconds, 95% confidence interval ?14.25 to 4.96, P=0.34).Conclusions: Outpatient therapist led rehabilitation was not superior to a single physiotherapist review and home exercise based regimen in patients at risk of poor outcomes after total knee arthroplasty. No clinically relevant differences were observed across primary or secondary outcome measures.Trials registration: Current Controlled Trials ISRCTN23357609 and ClinicalTrials.gov NCT01849445

Centile charts for birthweight for gestational age for Scottish singleton births

<p>Abstract</p> <p>Background</p> <p>Centile charts of birthweight for gestational age are used to identify low birthweight babies. The charts currently used in Scotland are based on data from the 1970s and require updating given changes in birthweight and in the measurement of gestational age since then.</p> <p>Methods</p> <p>Routinely collected data of 100,133 singleton births occurring in Scotland from 1998–2003 were used to construct new centile charts using the LMS method.</p> <p>Results</p> <p>Centile charts for birthweight for sex and parity groupings were constructed for singleton birth and compared to existing charts used in Scottish hospitals.</p> <p>Conclusion</p> <p>Mean birthweight has been shown to have increased over recent decades. The differences shown between the new and currently used centiles confirm the need for more up-to-date centiles for birthweight for gestational age.</p