Vector Meson Propagator and Baryon Current Conservation

If baryons couple only with $\omega$-mesons, one found the baryon spectral function may be negative. We show this unacceptable result is caused by the $k_\mu k_\nu$-terms in the $\omega$-meson propagator. Their contribution may not vanish in approximate calculations which violate the baryon current conserves. A rule is suggested, by which the calculated baryon spectral function is well behaved.Comment: 9 pages (LaTeX file), 3 figures (PostScript file

Coupled Dyson-Schwinger Equations and Effects of Self-Consistency

Using the $\sigma -\omega$ model as an effective tool, the effects of self-consistency are studied in some detail. A coupled set of Dyson-Schwinger equations for the renormalized baryon and meson propagators in the $\sigma -\omega$ model is solved self-consistently according to the dressed Hartree-Fock scheme, where the hadron propagators in both the baryon and meson self-energies are required to also satisfy this coupled set of equations. It is found that the self-consistency affects the baryon spectral function noticeably, if only the interaction with $\sigma$ mesons is considered. However, there is a cancellation between the effects due to the $\sigma$ and $\omega$ mesons and the additional contribution of $\omega$ mesons makes the above effect insignificant. In both the $\sigma$ and $\sigma -\omega$ cases the effects of self-consistency on meson spectral function are perceptible, but they can nevertheless be taken account of without a self-consistent calculation. Our study indicates that to include the meson propagators in the self-consistency requirement is unnecessary and one can stop at an early step of an iteration procedure to obtain a good approximation to the fully self-consistent results of all the hadron propagators in the model, if an appropriate initial input is chosen. Vertex corrections and their effects on ghost poles are also studied.Comment: 20 pages (include 5 tables), 17 figures (PostScript file

Contrasting mechanisms for crustal sulphur contamination of mafic magma: evidence from dyke and sill complexes from the British Palaeogene Igneous Province

This is the final version of the article. Available from the Geological Society via the DOI in this record.he addition of crustal sulphur to magma can trigger sulphide saturation, a process fundamental to the development of some Ni–Cu–PGE deposits. In the British Palaeogene Igneous Province, mafic and ultramafic magmas intrude a thick sedimentary sequence offering opportunities to elucidate mechanisms of magma–crust interaction in a setting with heterogeneous S isotope signatures. We present S-isotopic data from sills and dykes on the Isle of Skye. Sharp contrasts exist between variably light δ34S in Jurassic sedimentary sulphide (−35‰ to −10‰) and a local pristine magmatic δ34S signature of −2.3 ± 1.5‰. Flat-lying sills have restricted δ34S (−5‰ to 0‰) whereas steeply dipping dykes are more variable (−0‰ to −2‰). We suggest that the mechanism by which magma is intruded exerts a fundamental control on the degree of crustal contamination by volatile elements. Turbulent flow within narrow, steep magma conduits, discordant to sediments, and developed by brittle extension or dilation have maximum contamination potential. In contrast, sill-like conduits emplaced concordantly to sediments show little contamination by crustal S. The province is prospective for Ni–Cu–PGE mineralization analogous to the sill-hosted Noril’sk deposit, and Cu/Pd ratios of sills and dykes on Skye indicate that magmas had already reached S-saturation before reaching the present exposure level.Sulphur isotope analysis was undertaken at the Scottish Universities Environment Research Centre (SUERC) and funded by an NERC Isotope Geosciences Facilities Steering Committee grant (IP-1356-1112). H.S.R.H. would like to acknowledge the financial support of the Natural Environment Research Council (NERC) for funding this work (studentship NE/J50029X/1) and open access publication. A.J.B. is funded by NERC funding of the Isotope Community Support Facility at SUER

Access and utilisation of maternity care for disabled women who experience domestic abuse:a systematic review

BACKGROUND: Although disabled women are significantly more likely to experience domestic abuse during pregnancy than non-disabled women, very little is known about how maternity care access and utilisation is affected by the co-existence of disability and domestic abuse. This systematic review of the literature explored how domestic abuse impacts upon disabled women’s access to maternity services. METHODS: Eleven articles were identified through a search of six electronic databases and data were analysed to identify: the factors that facilitate or compromise access to care; the consequences of inadequate care for pregnant women’s health and wellbeing; and the effectiveness of existing strategies for improvement. RESULTS: Findings indicate that a mental health diagnosis, poor relationships with health professionals and environmental barriers can compromise women’s utilisation of maternity services. Domestic abuse can both compromise, and catalyse, access to services and social support is a positive factor when accessing care. Delayed and inadequate care has adverse effects on women’s physical and psychological health, however further research is required to fully explore the nature and extent of these consequences. Only one study identified strategies currently being used to improve access to services for disabled women experiencing abuse. CONCLUSIONS: Based upon the barriers and facilitators identified within the review, we suggest that future strategies for improvement should focus on: understanding women’s reasons for accessing care; fostering positive relationships; being women-centred; promoting environmental accessibility; and improving the strength of the evidence base

ESTRATÉGIAS UTILIZADAS POR ENFERMEIROS NA READAPTAÇÃO FUNCIONAL DE TRABALHADORES DE ENFERMAGEM

RESUMO Objetivo: conhecer as estratégias de enfermeiros ao receber o trabalhador de enfermagem em readaptação funcional. Metodologia: estudo qualitativo, descritivo exploratório, realizado em um hospital universitário no Sul do Brasil. Os dados foram coletados por meio de entrevista semiestruturada com 19 enfermeiros, entre maio e julho de 2016. Para análise e interpretação dos dados, optou-se pela proposta operativa de Minayo. Resultados: as informações convergiram para duas categorias: acolhimento e cuidado com o trabalhador em readaptação funcional no cenário laboral; planejamento do processo de readaptação do trabalhador de enfermagem. Conclusões: os enfermeiros perceberam o acolhimento, a negociação e o processo de comunicação, como estratégias a serem utilizadas para melhor readaptação do trabalhador de enfermagem que retorna ao trabalho permeado pelo cuidado e respeito às limitações laborais, requerendo uma integração entre a equipe e o membro readaptado

Flow Residence Time and Regions of Intraluminal Thrombus Deposition in Intracranial Aneurysms

Thrombus formation in intracranial aneurysms, while sometimes stabilizing lesion growth, can present additional risk of thrombo-embolism. The role of hemodynamics in the progression of aneurysmal disease can be elucidated by patient-specific computational modeling. In our previous work, patient-specific computational fluid dynamics (CFD) models were constructed from MRI data for three patients who had fusiform basilar aneurysms that were thrombus-free and then proceeded to develop intraluminal thrombus. In this study, we investigated the effect of increased flow residence time (RT) by modeling passive scalar advection in the same aneurysmal geometries. Non-Newtonian pulsatile flow simulations were carried out in base-line geometries and a new postprocessing technique, referred to as “virtual ink” and based on the passive scalar distribution maps, was used to visualize the flow and estimate the flow RT. The virtual ink technique clearly depicted regions of flow separation. The flow RT at different locations adjacent to aneurysmal walls was calculated as the time the virtual ink scalar remained above a threshold value. The RT values obtained in different areas were then correlated with the location of intra-aneurysmal thrombus observed at a follow-up MR study. For each patient, the wall shear stress (WSS) distribution was also obtained from CFD simulations and correlated with thrombus location. The correlation analysis determined a significant relationship between regions where CFD predicted either an increased RT or low WSS and the regions where thrombus deposition was observed to occur in vivo. A model including both low WSS and increased RT predicted thrombus-prone regions significantly better than the models with RT or WSS alone

Computational Analysis of Pulsed Radiofrequency Ablation in Treating Chronic Pain

In this paper, a parametric study has been conducted to evaluate the effects of frequency and duration of the short burst pulses during pulsed radiofrequency ablation (RFA) in treating chronic pain. Affecting the brain and nervous system, this disease remains one of the major challenges in neuroscience and clinical practice. A two-dimensional axisymmetric RFA model has been developed in which a single needle radiofrequency electrode has been inserted. A finite-element-based coupled thermo-electric analysis has been carried out utilizing the simplified Maxwell’s equations and the Pennes bioheat transfer equation to compute the electric field and temperature distributions within the computational domain. Comparative studies have been carried out between the continuous and pulsed RFA to highlight the significance of pulsed RFA in chronic pain treatment. The frequencies and durations of short burst RF pulses have been varied from 1 Hz to 10 Hz and from 10 ms to 50 ms, respectively. Such values are most commonly applied in clinical practices for mitigation of chronic pain. By reporting such critical input characteristics as temperature distributions for different frequencies and durations of the RF pulses, this computational study aims at providing the first-hand accurate quantitative information to the clinicians on possible consequences in those cases where these characteristics are varied during the pulsed RFA procedure. The results demonstrate that the efficacy of pulsed RFA is significantly dependent on the duration and frequency of the RF pulses

The Clinical Applications of a Systems Approach

In the second of a two part series, Ahn and colleagues provide a practical discussion of how a systems approach will affect clinical medicine, using diabetes as an example

The method of educational assessment affects children’s neural processing and performance: behavioural and fMRI Evidence.

Standardised educational assessments are now widespread, yet their development has given comparatively more consideration to what to assess than how to optimally assess students’ competencies. Existing evidence from behavioural studies with children and neuroscience studies with adults suggest that the method of assessment may affect neural processing and performance, but current evidence remains limited. To investigate the impact of assessment methods on neural processing and performance in young children, we used functional magnetic resonance imaging to identify and quantify the neural correlates during performance across a range of current approaches to standardised spelling assessment. Results indicated that children’s test performance declined as the cognitive load of assessment method increased. Activation of neural nodes associated with working memory further suggests that this performance decline may be a consequence of a higher cognitive load, rather than the complexity of the content. These findings provide insights into principles of assessment (re)design, to ensure assessment results are an accurate reflection of students’ true levels of competency