291 research outputs found

    Dirac spinor fields in the teleparallel gravity: comment on "Metric-affine approach to teleparallel gravity"

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    We show that the coupling of a Dirac spinor field with the gravitational field in the teleparallel equivalent of general relativity is consistent. For an arbitrary SO(3,1) connection there are two possibilities for the coupling of the spinor field with the gravitational field. The problems of consistency raised by Y. N. Obukhov and J. G. Pereira in the paper {\it Metric-affine approach to teleparallel gravity} [gr-qc/0212080] take place only in the framework of one particular coupling. By adopting an alternative coupling the consistency problem disappears.Comment: 8 pages, Latex file, no figures, to appear in the Phys. Rev. D as a Commen

    Luciferase-free Luciferin Electrochemiluminescence

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    Luciferin is one of Nature's most widespread luminophores, and enzymes that catalyze luciferin luminescence are the basis of successful commercial “glow” assays for gene expression and metabolic ATP formation. Herein we report an electrochemical method to promote firefly's luciferin luminescence in the absence of its natural biocatalyst—luciferase. We have gained experimental and computational insights on the mechanism of the enzyme-free luciferin electrochemiluminescence, demonstrated its spectral tuning from green to red by means of electrolyte engineering, proven that the colour change does not require, as still debated, a keto/enol isomerization of the light emitter, and gained evidence of the electrostatic-assisted stabilization of the charge-transfer excited state by double layer electric fields. Luciferin's electrochemiluminescence, as well as the in situ generation of fluorescent oxyluciferin, are applied towards an optical measurement of diffusion coefficients

    Teleparallel formalism of galilean gravity

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    A pseudo-Riemannian manifold is introduced, with light-cone coordinates in (4+1) dimensional space-time, to describe a Galilei covariant gravity. The notion of 5-bein and torsion are developed and a galilean version of teleparallelism is constructed in this manifold. The formalism is applied to two spherically symmetric configurations. The first one is an ansatz which is inferred by following the Schwarzschild solution in general relativity. The second one is a solution of galilean covariant equations. In addition, this Galilei teleparallel approach provides a prescription to couple the 5-bein field to the galilean covariant Dirac field.Comment: 10 page

    Exclusionary employment in Britain’s broken labour market

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    There is growing evidence of the problematic nature of the UK’s ‘flexible labour market’ with rising levels of in-work poverty and insecurity. Yet successive Governments have stressed that paid work is the route to inclusion, focussing attention on the divide between employed and unemployed. Past efforts to measure social exclusion have tended to make the same distinction. The aim of this paper is to apply Levitas et al’s (2007) framework to assess levels of exclusionary employment, i.e. exclusion arising directly from an individual’s labour market situation. Using data from the Poverty and Social Exclusion UK survey, results show that one in three adults in paid work is in poverty, or in insecure or poor quality employment. One third of this group have not seen any progression in their labour market situation in the last five years. The policy focus needs to shift from ‘Broken Britain’ to Britain’s broken labour market

    Public involvement in the priority setting activities of a wait time management initiative: a qualitative case study

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    <p>Abstract</p> <p>Background</p> <p>As no health system can afford to provide all possible services and treatments for the people it serves, each system must set priorities. Priority setting decision makers are increasingly involving the public in policy making. This study focuses on public engagement in a key priority setting context that plagues every health system around the world: wait list management. The purpose of this study is to describe and evaluate priority setting for the Ontario Wait Time Strategy, with special attention to public engagement.</p> <p>Methods</p> <p>This study was conducted at the Ontario Wait Time Strategy in Ontario, Canada which is part of a Federal-Territorial-Provincial initiative to improve access and reduce wait times in five areas: cancer, cardiac, sight restoration, joint replacements, and diagnostic imaging. There were two sources of data: (1) over 25 documents (e.g. strategic planning reports, public updates), and (2) 28 one-on-one interviews with informants (e.g. OWTS participants, MOHLTC representatives, clinicians, patient advocates). Analysis used a modified thematic technique in three phases: open coding, axial coding, and evaluation.</p> <p>Results</p> <p>The Ontario Wait Time Strategy partially meets the four conditions of 'accountability for reasonableness'. The public was not directly involved in the priority setting activities of the Ontario Wait Time Strategy. Study participants identified both benefits (supporting the initiative, experts of the lived experience, a publicly funded system and sustainability of the healthcare system) and concerns (personal biases, lack of interest to be involved, time constraints, and level of technicality) for public involvement in the Ontario Wait Time Strategy. Additionally, the participants identified concern for the consequences (sustainability, cannibalism, and a class system) resulting from the Ontario Wait Times Strategy.</p> <p>Conclusion</p> <p>We described and evaluated a wait time management initiative (the Ontario Wait Time Strategy) with special attention to public engagement, and provided a concrete plan to operationalize a strategy for improving public involvement in this, and other, wait time initiatives.</p

    European Reference Network for Rare Vascular Diseases (VASCERN) position statement on cerebral screening in adults and children with hereditary haemorrhagic telangiectasia (HHT)

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    Hereditary haemorrhagic telangiectasia (HHT) is a multisystemic vascular dysplasia inherited as an autosomal dominant trait. Approximately 10 % of patients have cerebral vascular malformations, a proportion being cerebral arteriovenous malformations (AVMs) and fistulae that may lead to potentially devastating consequences in case of rupture. On the other hand, detection and treatment related-risks are not negligible, and immediate. While successful treatment can be undertaken in individual cases, current data do not support the treatment of unruptured AVMs, which also present a low risk of bleeding in HHT patients. Screening for these AVMs is therefore controversial. Structured discussions, distinctions of different cerebrovascular abnormalities commonly grouped into an "AVM"bracket, and clear guidance by neurosurgical and neurointerventional radiology colleagues enabled the European Reference Network for Rare Vascular Disorders (VASCERN-HHT) to develop the following agreed Position Statement on cerebral screening: 1) First, we emphasise that neurological symptoms suggestive of cerebral AVMs in HHT patients should be investigated as in general neurological and emergency care practice. Similarly, if an AVM is found accidentally, management approaches should rely on expert discussions on a case-by-case basis and individual risk-benefit evaluation of all therapeutic possibilities for a specific lesion. 2) The current evidence base does not favour the treatment of unruptured cerebral AVMs, and therefore cannot be used to support widespread screening of asymptomatic HHT patients. 3) Individual situations encompass a wide range of personal, cultural and clinical states. In order to enable informed patient choice, and avoid conflicting advice, particularly arising from non-neurovascular interpretations of the evidence base, we suggest that all HHT patients should have the opportunity to discuss knowingly brain screening issues with their healthcare provider. 4) Any screening discussions in asymptomatic individuals should be preceded by informed pre-test review of the latest evidence regarding preventative and therapeutic efficacies of any interventions. The possibility of harm due to detection of, or intervention on, a vascular malformation that would not have necessarily caused any consequence in later life should be stated explicitly. We consider this nuanced Position Statement provides a helpful, evidence-based framework for informed discussions between healthcare providers and patients in an emotionally charged area

    Intravenous alteplase for stroke with unknown time of onset guided by advanced imaging: systematic review and meta-analysis of individual patient data

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    Background: Patients who have had a stroke with unknown time of onset have been previously excluded from thrombolysis. We aimed to establish whether intravenous alteplase is safe and effective in such patients when salvageable tissue has been identified with imaging biomarkers. Methods: We did a systematic review and meta-analysis of individual patient data for trials published before Sept 21, 2020. Randomised trials of intravenous alteplase versus standard of care or placebo in adults with stroke with unknown time of onset with perfusion-diffusion MRI, perfusion CT, or MRI with diffusion weighted imaging-fluid attenuated inversion recovery (DWI-FLAIR) mismatch were eligible. The primary outcome was favourable functional outcome (score of 0–1 on the modified Rankin Scale [mRS]) at 90 days indicating no disability using an unconditional mixed-effect logistic-regression model fitted to estimate the treatment effect. Secondary outcomes were mRS shift towards a better functional outcome and independent outcome (mRS 0–2) at 90 days. Safety outcomes included death, severe disability or death (mRS score 4–6), and symptomatic intracranial haemorrhage. This study is registered with PROSPERO, CRD42020166903. Findings: Of 249 identified abstracts, four trials met our eligibility criteria for inclusion: WAKE-UP, EXTEND, THAWS, and ECASS-4. The four trials provided individual patient data for 843 individuals, of whom 429 (51%) were assigned to alteplase and 414 (49%) to placebo or standard care. A favourable outcome occurred in 199 (47%) of 420 patients with alteplase and in 160 (39%) of 409 patients among controls (adjusted odds ratio [OR] 1·49 [95% CI 1·10–2·03]; p=0·011), with low heterogeneity across studies (I2=27%). Alteplase was associated with a significant shift towards better functional outcome (adjusted common OR 1·38 [95% CI 1·05–1·80]; p=0·019), and a higher odds of independent outcome (adjusted OR 1·50 [1·06–2·12]; p=0·022). In the alteplase group, 90 (21%) patients were severely disabled or died (mRS score 4–6), compared with 102 (25%) patients in the control group (adjusted OR 0·76 [0·52–1·11]; p=0·15). 27 (6%) patients died in the alteplase group and 14 (3%) patients died among controls (adjusted OR 2·06 [1·03–4·09]; p=0·040). The prevalence of symptomatic intracranial haemorrhage was higher in the alteplase group than among controls (11 [3%] vs two [&lt;1%], adjusted OR 5·58 [1·22–25·50]; p=0·024). Interpretation: In patients who have had a stroke with unknown time of onset with a DWI-FLAIR or perfusion mismatch, intravenous alteplase resulted in better functional outcome at 90 days than placebo or standard care. A net benefit was observed for all functional outcomes despite an increased risk of symptomatic intracranial haemorrhage. Although there were more deaths with alteplase than placebo, there were fewer cases of severe disability or death. Funding: None

    A Systematic Review on the Diagnosis of Pediatric Bacterial Pneumonia: When Gold Is Bronze

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    In developing countries, pneumonia is one of the leading causes of death in children under five years of age and hence timely and accurate diagnosis is critical. In North America, pneumonia is also a common source of childhood morbidity and occasionally mortality. Clinicians traditionally have used the chest radiograph as the gold standard in the diagnosis of pneumonia, but they are becoming increasingly aware that it is not ideal. Numerous studies have shown that chest radiography findings lack precision in defining the etiology of childhood pneumonia. There is no single test that reliably distinguishes bacterial from non-bacterial causes. These factors have resulted in clinicians historically using a combination of physical signs and chest radiographs as a 'gold standard', though this combination of tests has been shown to be imperfect for diagnosis and assigning treatment. The objectives of this systematic review are to: 1) identify and categorize studies that have used single or multiple tests as a gold standard for assessing accuracy of other tests, and 2) given the 'gold standard' used, determine the accuracy of these other tests for diagnosing childhood bacterial pneumonia.Search strategies were developed using a combination of subject headings and keywords adapted for 18 electronic bibliographic databases from inception to May 2008. Published studies were included if they: 1) included children one month to 18 years of age, 2) provided sufficient data regarding diagnostic accuracy to construct a 2x2 table, and 3) assessed the accuracy of one or more index tests as compared with other test(s) used as a 'gold standard'. The literature search revealed 5,989 references of which 256 were screened for inclusion, resulting in 25 studies that satisfied all inclusion criteria. The studies examined a range of bacterium types and assessed the accuracy of several combinations of diagnostic tests. Eleven different gold standards were studied in the 25 included studies. Criterion validity was calculated for fourteen different index tests using eleven different gold standards. The most common gold standard utilized was blood culture tests used in six studies. Fourteen different tests were measured as index tests. PCT was the most common measured in five studies each with a different gold standard.We have found that studies assessing the diagnostic accuracy of clinical, radiological, and laboratory tests for bacterial childhood pneumonia have used a heterogeneous group of gold standards, and found, at least in part because of this, that index tests have widely different accuracies. These findings highlight the need for identifying a widely accepted gold standard for diagnosis of bacterial pneumonia in children

    Biobanking and consenting to research: a qualitative thematic analysis of young people’s perspectives in the North East of England

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    Background: Biobanking biospecimens and consent are common practice in paediatric research. We need to explore children and young people’s (CYP) knowledge and perspectives around the use of and consent to biobanking. This will ensure meaningful informed consent can be obtained and improve current consent procedures. Methods: We designed a survey, in co-production with CYP, collecting demographic data, views on biobanking, and consent using three scenarios: 1) prospective consent, 2) deferred consent, and 3) reconsent and assent at age of capacity. The survey was disseminated via the Young Person’s Advisory Group North England (YPAGne) and participating CYP’s secondary schools. Data were analysed using a qualitative thematic approach by three independent reviewers (including CYP) to identify common themes. Data triangulation occurred independently by a fourth reviewer. Results: One hundred two CYP completed the survey. Most were between 16–18 years (63.7%, N = 65) and female (66.7%, N = 68). 72.3% had no prior knowledge of biobanking (N = 73). Acceptability of prospective consent for biobanking was high (91.2%, N = 93) with common themes: ‘altruism’, ‘potential benefits outweigh individual risk’, 'frugality', and ‘(in)convenience’. Deferred consent was also deemed acceptable in the large majority (84.3%, N = 86), with common themes: ‘altruism’, ‘body integrity’ and ‘sample frugality’. 76.5% preferred to reconsent when cognitively mature enough to give assent (N = 78), even if parental consent was previously in place. 79.2% wanted to be informed if their biobanked biospecimen is reused (N = 80). Conclusion: Prospective and deferred consent acceptability for biobanking is high among CYP in the UK. Altruism, frugality, body integrity, and privacy are the most important themes. Clear communication and justification are paramount to obtain consent. Any CYP with capacity should be part of the consenting procedure, if possible
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