Beam characterisation and machine development at VELA

An overview is presented of developments on VELA (Versatile Electron Linear Accelerator), an RF photoinjector with two user stations (beam areas BA1, and BA2) at Daresbury Laboratory. Numerous machine development, commissioning, beam characterisation and user experiments have been completed in the past year. A new beamline and a dedicated multi-purpose chamber have been commissioned in BA1 and the first experiments performed. A number of measures have been taken to improve the stability of machine by mitigating problems with a phase drift, laser beam transport drift and a coherent beam oscillation. The 6D phase space of the electron beam has been characterised through quadrupole scans, transverse tomography and with a transverse deflecting cavity

Increased impedance near cut-off in plasma-like media leading to emission of high-power, narrow-bandwidth radiation

Ultra-intense, narrow-bandwidth, electromagnetic pulses have become important tools for exploring the characteristics of matter. Modern tuneable high-power light sources, such as free-electron lasers and vacuum tubes, rely on bunching of relativistic or near-relativistic electrons in vacuum. Here we present a fundamentally different method for producing narrow-bandwidth radiation from a broad spectral bandwidth current source, which takes advantage of the inflated radiation impedance close to cut-off in a medium with a plasma-like permittivity. We find that by embedding a current source in this cut-off region, more than an order of magnitude enhancement of the radiation intensity is obtained compared with emission directly into free space. The method suggests a simple and general way to flexibly use broadband current sources to produce broad or narrow bandwidth pulses. As an example, we demonstrate, using particle-in-cell simulations, enhanced monochromatic emission of terahertz radiation using a two-colour pumped current source enclosed by a tapered waveguide.ope

Psychopathology predicts the outcome of medial branch blocks with corticosteroid for chronic axial low back or cervical pain: a prospective cohort study

<p>Abstract</p> <p>Background</p> <p>Comorbid psychopathology is an important predictor of poor outcome for many types of treatments for back or neck pain. But it is unknown if this applies to the results of medial branch blocks (MBBs) for chronic low back or neck pain, which involves injecting the medial branch of the dorsal ramus nerves that innervate the facet joints. The objective of this study was to determine whether high levels of psychopathology are predictive of pain relief after MBB injections in the lumbar or cervical spine.</p> <p>Methods</p> <p>This was a prospective cohort study. Consecutive patients in a pain medicine practice undergoing MBBs of the lumbar or cervical facets with corticosteroids were recruited to participate. Subjects were selected for a MBB based on operationalized selection criteria and the procedure was performed in a standardized manner. Subjects completed the Brief Pain Inventory (BPI) and the Hospital Anxiety and Depression Scale (HADS) just prior to the procedure and at one-month follow up. Scores on the HADS classified the subjects into three groups based on psychiatric symptoms, which formed the primary predictor variable: <it>Low</it>, <it>Moderate</it>, or <it>High </it>levels of psychopathology. The primary outcome measure was the percent improvement in average daily pain rating one-month following an injection. Analysis of variance and chi-square were used to analyze the analgesia and functional rating differences between groups, and to perform a responder analysis.</p> <p>Results</p> <p>Eighty six (86) subjects completed the study. The <it>Low </it>psychopathology group (n = 37) reported a mean of 23% improvement in pain at one-month while the <it>High </it>psychopathology group (n = 29) reported a mean worsening of -5.8% in pain (p < .001). Forty five percent (45%) of the <it>Low </it>group had at least 30% improvement in pain versus 10% in the <it>High </it>group (p < .001). Using an analysis of covariance, no baseline demographic, social, or medical variables were significant predictors of pain improvement, nor did they mitigate the effect of psychopathology on the outcome.</p> <p>Conclusion</p> <p>Psychiatric comorbidity is associated with diminished pain relief after a MBB injection performed with steroid at one-month follow-up. These findings illustrate the importance of assessing comorbid psychopathology as part of a spine care evaluation.</p

250 labels used to stigmatise people with mental illness

<p>Abstract</p> <p>Background</p> <p>The stigma against people with mental illness is a major barrier to help-seeking in young people for mental health problems. The objective of this study was to investigate the extent of stigma in relation to treatment avoidance in 14 year-old school students in England in relation to how they refer to people with mental illness.</p> <p>Methods</p> <p>This is a qualitative, cross-sectional study. The data were gathered as part of the baseline assessment for an intervention study intended to reduce stigma among 14 year old school students. The participating schools were two grammar (selective) schools and three comprehensive (non-selective) schools. At the start of the lesson, the students were asked 'What sorts of words or phrases might you use to describe someone who experiences mental health problems?' Words and terms used to refer to mental illness were enumerated. Using the grounded theory approach, words and terms were grouped in terms of their denotative and connotative meanings. Labels were then derived to capture the key themes attached by the students to the concepts of mental illness. The frequencies of occurrence for each word were also tabulated.</p> <p>Results</p> <p>400 of the 472 participating students (85%) provided 250 words and terms to describe a person with mental illness. Five themes were identified from the data. The first theme called 'popular derogatory terms' (116 items) accounted for nearly half of the words examined. The second theme occurred less often and was described as 'negative emotional state' (61 items). The third theme demonstrated the confusion of young people between physical disabilities, learning difficulties and mental health problems (38 items). The use of psychiatric diagnoses (15 items) and terms related to violence (9 items) were unexpectedly uncommon.</p> <p>Conclusion</p> <p>Our findings suggest the hypothesis that help-seeking by mentally ill young people may be improved by interventions that address both their lack of factual information about mental illness, and those which reduce their strong negative emotional reactions towards people with mental illness.</p

Universal health coverage from multiple perspectives: a synthesis of conceptual literature and global debates

Background: There is an emerging global consensus on the importance of universal health coverage (UHC), but no unanimity on the conceptual definition and scope of UHC, whether UHC is achievable or not, how to move towards it, common indicators for measuring its progress, and its long-term sustainability. This has resulted in various interpretations of the concept, emanating from different disciplinary perspectives. This paper discusses the various dimensions of UHC emerging from these interpretations and argues for the need to pay attention to the complex interactions across the various components of a health system in the pursuit of UHC as a legal human rights issue. Discussion: The literature presents UHC as a multi-dimensional concept, operationalized in terms of universal population coverage, universal financial protection, and universal access to quality health care, anchored on the basis of health care as an international legal obligation grounded in international human rights laws. As a legal concept, UHC implies the existence of a legal framework that mandates national governments to provide health care to all residents while compelling the international community to support poor nations in implementing this right. As a humanitarian social concept, UHC aims at achieving universal population coverage by enrolling all residents into health-related social security systems and securing equitable entitlements to the benefits from the health system for all. As a health economics concept, UHC guarantees financial protection by providing a shield against the catastrophic and impoverishing consequences of out-of-pocket expenditure, through the implementation of pooled prepaid financing systems. As a public health concept, UHC has attracted several controversies regarding which services should be covered: comprehensive services vs. minimum basic package, and priority disease-specific interventions vs. primary health care. Summary: As a multi-dimensional concept, grounded in international human rights laws, the move towards UHC in LMICs requires all states to effectively recognize the right to health in their national constitutions. It also requires a human rights-focused integrated approach to health service delivery that recognizes the health system as a complex phenomenon with interlinked functional units whose effective interaction are essential to reach the equilibrium called UHC