Parametric resonance of Alfvén waves driven by ionization-recombination waves in the weakly ionized solar atmosphere

Parametric coupling of waves is one of the most efficient mechanisms of energy transfer that can lead to the growth or decay of waves. This transfer occurs at frequencies close to their natural frequencies. In partially ionized solar plasma, there are a multitude of waves that can undergo this process. Here, we study the parametric coupling of Alfvén waves propagating in a partially ionized solar plasma with ionization-recombination waves identified by our study to appear in a plasma in ionization non-equilibrium. Depending on the parameters that describe the plasma (density, temperature), coupling can lead to a parametric resonance. Our study determines the occurrence conditions of parametric resonance, by finding the boundaries between stable and unstable regions in the parameter space. Our results show that collisions and non-equilibrium recombination can both contribute to the onset of unstable behaviour of parametrically resonant Alfvén waves. This article is part of the theme issue 'Partially ionized plasma of the solar atmosphere: recent advances and future pathways'.

Exercise for depression

Depression is a common and important cause of morbidity and mortality worldwide. It is commonly treated with antidepressants and/or psychological therapy, but some people prefer alternative approaches such as exercise. There are a number of theoretical reasons why exercise may improve depression. This is an update of a review first published in 2009.

Association between retinal vasculature and muscle mass in older people

Sarcopenia in older people is a major health issue and its early detection could help target interventions and improve health. Evidence suggests that poor muscle mass is associated with greater arterial stiffness and cardiovascular risk. Arterial stiffness in turn is associated with smaller retinal artery width. This study examined the association of muscle mass in older people with retinal vascular width, a non-invasive measure of vascular function.

METHODS

Participants >65 years were recruited to a cross-sectional study.

EXCLUSIONS

Inability to walk independently; diabetes mellitus; stroke (within 6 months), severe macular degeneration, glaucoma, retinal dystrophy; advanced cataract. Digital Retinal images of both eyes were analysed using the VAMPIRE software suite. Central Retinal Artery and Vein Equivalents (CRVE and CRAE) were measured. Body composition was measured using Dual Energy X ray Absorptimetry (DXA). Appendicular Skeletal Muscle Mass/Height(2) was calculated. Physical function was measured: 6-min walk distance, Short Physical performance battery, handgrip strength and quadriceps strength.

RESULTS

79 participants with mean age 72 (SD 6) years were recruited. 44% were female. Digital Retinal images of sufficient quality for measuring CRAE and CRVE were available for 51/75 (68%) of participants. Regression analysis showed significant association between larger ASMM/H(2) and smaller CRAE (β=-0.20, p=0.001) and CRVE (β=-0.12, p=0.05). Handgrip strength, body mass index and sex combined with CRAE explained 88% and with CRVE explained 86% of the variance in ASMM/H(2).

CONCLUSION

Larger muscle mass was significantly associated with smaller retinal artery size in older people. This unexpected finding needs further investigation.

Construction of a linked health and social care database resource--lessons on process, content and culture

BACKGROUND

Combining routinely collected health and social care data on older people is essential to advance both service delivery and research for this client group. Little data is available on how to combine health and social care data; this article provides an overview of a successful data linkage process and discusses potential barriers to executing such projects.

METHODS AND RESULTS

We successfully obtained and linked data on older people within Dundee from three sources: Dundee Social Work Department database (30,000 individuals aged 65 years and over), healthcare data held on NHS Tayside patients by the Health Informatics Centre (400,000 individuals), Dundee, and the Dundee of Medicine for the Elderly rehabilitation database (4300 individuals). Data were linked, anonymized and transferred to a Safe Haven environment to ensuring confidentiality and strict access control. Challenges were faced around workflows, culture and documentation. Exploiting the resultant data set raises further challenges centered on database documentation, understanding the way data were collected, dealing with missing data, data validity and collection at different time periods.

CONCLUSION

Routinely collected health and social care data sets can be linked, but significant process barriers must be overcome to allow successful linkage and integration of data and its full exploitation.

Do ACE inhibitors improve the response to exercise training in functionally impaired older adults? A randomized controlled trial

Background.

Loss of muscle mass and strength with ageing is a major cause for falls, disability, and morbidity in older people. Previous studies have found that angiotensin-converting enzyme inhibitors (ACEi) may improve physical function in older people. It is unclear whether ACEi provide additional benefit when added to a standard exercise training program. We examined the effects of ACEi therapy on physical function in older people undergoing exercise training.

Methods.

Community-dwelling people aged ≥65 years with functional impairment were recruited through general (family) practices. All participants received progressive exercise training. Participants were randomized to receive either 4 mg perindopril or matching placebo daily for 20 weeks. The primary outcome was between-group change in 6-minute walk distance from baseline to 20 weeks. Secondary outcomes included changes in Short Physical Performance Battery, handgrip and quadriceps strength, self-reported quality of life using the EQ-5D, and functional impairment measured using the Functional Limitations Profile.

Results.

A total of 170 participants (n = 86 perindopril, n = 84 placebo) were randomized. Mean age was 75.7 (standard deviation [SD] 6.8) years. Baseline 6-minute walk distance was 306 m (SD 99). Both groups increased their walk distance (by 29.6 m perindopril, 36.4 m placebo group) at 20 weeks, but there was no statistically significant treatment effect between groups (−8.6m [95% confidence interval: −30.1, 12.9], p = .43). No statistically significant treatment effects were observed between groups for the secondary outcomes. Adverse events leading to withdrawal were few (n = 0 perindopril, n = 4 placebo).

Interpretation.

ACE inhibitors did not enhance the effect of exercise training on physical function in functionally impaired older people.

Exercise for depression

BACKGROUND

Depression is a common and important cause of morbidity and mortality worldwide. Depression is commonly treated with antidepressants and/or psychological therapy, but some people may prefer alternative approaches such as exercise. There are a number of theoretical reasons why exercise may improve depression. This is an update of an earlier review first published in 2009.

OBJECTIVES

To determine the effectiveness of exercise in the treatment of depression in adults compared with no treatment or a comparator intervention.

SEARCH METHODS

We searched the Cochrane Depression, Anxiety and Neurosis Review Group's Controlled Trials Register (CCDANCTR) to 13 July 2012. This register includes relevant randomised controlled trials from the following bibliographic databases: The Cochrane Library (all years); MEDLINE (1950 to date); EMBASE (1974 to date) and PsycINFO (1967 to date). We also searched www.controlled-trials.com, ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform. No date or language restrictions were applied to the search.We conducted an additional search of the CCDANCTR up to 1st March 2013 and any potentially eligible trials not already included are listed as 'awaiting classification.'

SELECTION CRITERIA

Randomised controlled trials in which exercise (defined according to American College of Sports Medicine criteria) was compared to standard treatment, no treatment or a placebo treatment, pharmacological treatment, psychological treatment or other active treatment in adults (aged 18 and over) with depression, as defined by trial authors. We included cluster trials and those that randomised individuals. We excluded trials of postnatal depression.

DATA COLLECTION AND ANALYSIS

Two review authors extracted data on primary and secondary outcomes at the end of the trial and end of follow-up (if available). We calculated effect sizes for each trial using Hedges' g method and a standardised mean difference (SMD) for the overall pooled effect, using a random-effects model risk ratio for dichotomous data. Where trials used a number of different tools to assess depression, we included the main outcome measure only in the meta-analysis. Where trials provided several 'doses' of exercise, we used data from the biggest 'dose' of exercise, and performed sensitivity analyses using the lower 'dose'. We performed subgroup analyses to explore the influence of method of diagnosis of depression (diagnostic interview or cut-off point on scale), intensity of exercise and the number of sessions of exercise on effect sizes. Two authors performed the 'Risk of bias' assessments. Our sensitivity analyses explored the influence of study quality on outcome.

MAIN RESULTS

Thirty-nine trials (2326 participants) fulfilled our inclusion criteria, of which 37 provided data for meta-analyses. There were multiple sources of bias in many of the trials; randomisation was adequately concealed in 14 studies, 15 used intention-to-treat analyses and 12 used blinded outcome assessors.For the 35 trials (1356 participants) comparing exercise with no treatment or a control intervention, the pooled SMD for the primary outcome of depression at the end of treatment was -0.62 (95% confidence interval (CI) -0.81 to -0.42), indicating a moderate clinical effect. There was moderate heterogeneity (I² = 63%).When we included only the six trials (464 participants) with adequate allocation concealment, intention-to-treat analysis and blinded outcome assessment, the pooled SMD for this outcome was not statistically significant (-0.18, 95% CI -0.47 to 0.11). Pooled data from the eight trials (377 participants) providing long-term follow-up data on mood found a small effect in favour of exercise (SMD -0.33, 95% CI -0.63 to -0.03).Twenty-nine trials reported acceptability of treatment, three trials reported quality of life, none reported cost, and six reported adverse events.For acceptability of treatment (assessed by number of drop-outs during the intervention), the risk ratio was 1.00 (95% CI 0.97 to 1.04).Seven trials compared exercise with psychological therapy (189 participants), and found no significant difference (SMD -0.03, 95% CI -0.32 to 0.26). Four trials (n = 300) compared exercise with pharmacological treatment and found no significant difference (SMD -0.11, -0.34, 0.12). One trial (n = 18) reported that exercise was more effective than bright light therapy (MD -6.40, 95% CI -10.20 to -2.60).For each trial that was included, two authors independently assessed for sources of bias in accordance with the Cochrane Collaboration 'Risk of bias' tool. In exercise trials, there are inherent difficulties in blinding both those receiving the intervention and those delivering the intervention. Many trials used participant self-report rating scales as a method for post-intervention analysis, which also has the potential to bias findings.

AUTHORS' CONCLUSIONS

Exercise is moderately more effective than a control intervention for reducing symptoms of depression, but analysis of methodologically robust trials only shows a smaller effect in favour of exercise. When compared to psychological or pharmacological therapies, exercise appears to be no more effective, though this conclusion is based on a few small trials.

Exercise for depression

BACKGROUND

Depression is a common and important cause of morbidity and mortality worldwide. Depression is commonly treated with antidepressants and/or psychotherapy, but some people may prefer alternative approaches such as exercise. There are a number of theoretical reasons why exercise may improve depression. This is an update of an earlier review first published in 2009.

OBJECTIVES

To determine the effectiveness of exercise in the treatment of depression. Our secondary outcomes included drop-outs from exercise and control groups, costs, quality of life and adverse events.

SEARCH METHODS

We searched the Cochrane Depression, Anxiety and Neurosis (CCDAN) Review Group's Specialised Register (CCDANCTR), CENTRAL, MEDLINE, EMBASE, Sports Discus and PsycINFO for eligible studies (to February 2010). We also searched www.controlled-trials.com in November 2010. The CCDAN Group searched its Specialised Register in June 2011 and potentially eligible trials were listed as 'awaiting assessment'.

SELECTION CRITERIA

Randomised controlled trials in which exercise was compared to standard treatment, no treatment or a placebo treatment in adults (aged 18 and over) with depression, as defined by trial authors. We excluded trials of postnatal depression.

DATA COLLECTION AND ANALYSIS

For this update, two review authors extracted data on outcomes at the end of the trial. We used these data to calculate effect sizes for each trial using Hedges' g method and a standardised mean difference (SMD) for the overall pooled effect, using a random-effects model. Where trials used a number of different tools to assess depression, we included the main outcome measure only in the meta-analysis. We systematically extracted data on adverse effects and two authors performed the 'Risk of bias' assessments.

MAIN RESULTS

Thirty-two trials (1858 participants) fulfilled our inclusion criteria, of which 30 provided data for meta-analyses. Randomisation was adequately concealed in 11 studies, 12 used intention-to-treat analyses and nine used blinded outcome assessors. For the 28 trials (1101 participants) comparing exercise with no treatment or a control intervention, at post-treatment analysis the pooled SMD was -0.67 (95% confidence interval (CI) -0.90 to -0.43), indicating a moderate clinical effect. However, when we included only the four trials (326 participants) with adequate allocation concealment, intention-to-treat analysis and blinded outcome assessment, the pooled SMD was -0.31 (95% CI -0.63 to 0.01) indicating a small effect in favour of exercise. There was no difference in drop-outs between exercise and control groups. Pooled data from the seven trials (373 participants) that provided long-term follow-up data also found a small effect in favour of exercise (SMD -0.39, 95% CI -0.69 to -0.09). Of the six trials comparing exercise with cognitive behavioural therapy (152 participants), the effect of exercise was not significantly different from that of cognitive therapy. There were insufficient data to determine risks, costs and quality of life.Five potentially eligible studies identified by the search of the CCDAN Specialised Register in 2011 are listed as 'awaiting classification' and will be included in the next update of this review.

AUTHORS' CONCLUSIONS

Exercise seems to improve depressive symptoms in people with a diagnosis of depression when compared with no treatment or control intervention, however since analyses of methodologically robust trials show a much smaller effect in favour of exercise, some caution is required in interpreting these results.

Exercise for depression

BACKGROUND

Depression is a common and important cause of morbidity and mortality worldwide. Depression is commonly treated with antidepressants and/or psychotherapy, but some people may prefer alternative approaches such as exercise. There are a number of theoretical reasons why exercise may improve depression.

OBJECTIVES

To determine the effectiveness of exercise in the treatment of depression.

SEARCH STRATEGY

We searched Medline, Embase, Sports Discus, PsycINFO, the Cochrane Controlled Trials Register, and the Cochrane Database of Systematic Reviews for eligible studies in March 2007. In addition, we hand-searched several relevant journals, contacted experts in the field, searched bibliographies of retrieved articles, and performed citation searches of identified studies. We also searched www.controlled-trials.com in May 2008.

SELECTION CRITERIA

Randomised controlled trials in which exercise was compared to standard treatment, no treatment or a placebo treatment in adults (aged 18 and over) with depression, as defined by trial authors. We excluded trials of post-natal depression.

DATA COLLECTION AND ANALYSIS

We calculated effect sizes for each trial using Cohen's method and a standardised mean difference (SMD) for the overall pooled effect, using a random effects model. Where trials used a number of different tools to assess depression, we included the main outcome measure only in the meta-analysis.

MAIN RESULTS

Twenty-eight trials fulfilled our inclusion criteria, of which 25 provided data for meta-analyses. Randomisation was adequately concealed in a minority of studies, most did not use intention to treat analyses and most used self-reported symptoms as outcome measures. For the 23 trials (907 participants) comparing exercise with no treatment or a control intervention, the pooled SMD was -0.82 (95% CI -1.12, -0.51), indicating a large clinical effect. However, when we included only the three trials with adequate allocation concealment and intention to treat analysis and blinded outcome assessment, the pooled SMD was -0.42 (95% CI -0.88, 0.03) i.e. moderate, non-significant effect. The effect of exercise was not significantly different from that of cognitive therapy. There was insufficient data to determine risks and costs.

AUTHORS' CONCLUSIONS

Exercise seems to improve depressive symptoms in people with a diagnosis of depression, but when only methodologically robust trials are included, the effect sizes are only moderate and not statistically significant. Further, more methodologically robust trials should be performed to obtain more accurate estimates of effect sizes, and to determine risks and costs. Further systematic reviews could be performed to investigate the effect of exercise in people with dysthymia who do not fulfil diagnostic criteria for depression.

Day length and weather conditions profoundly affect physical activity levels in older functionally impaired people

BACKGROUND

Regular physical activity is vital for maintaining the health and independence of older people. Few objective data exist on the effect of weather on physical activity levels in this group. The objective of this study was to evaluate the effect of weather using an objective measure of physical activity.

METHODS

This was a retrospective study of 127 participants, >65 years old, who were enrolled in a previous randomised controlled trial. The main outcome was daily activity counts measured using the RT3 triaxial accelerometer over 1-week periods. These were correlated with local weather data including daily maximum temperature, sunshine, precipitation and wind speed that were obtained from the metrological office.

RESULTS

The mean age of the subjects was 78.6 years; 90/127 were female; and 720 usable daily counts were obtained for the 127 participants. The mean daily counts showed a striking seasonal variation, with maximum activity in June and minimum in February (137 557 vs 65 010 counts per day, p<0.001). Day length, mean maximum temperature and mean daily sunshine were able to explain 72.9% of the monthly variance in daily activity levels. Daily counts showed moderate correlation with day length (r = 0.358, p<0.001), maximum temperature (r = 0.345, p<0.001), duration of sunshine (r = 0.313, p<0.001) and rain (r = -0.098, p = 0.008) but not with wind speed (r = 0.093, p = 0.12). Multivariate analysis showed that day length, sunshine duration and maximum temperature were independent predictors of daily activity (adjusted R(2) = 0.16).

CONCLUSIONS

Physical activity levels among older people are much higher in summer than in winter. Day length, sunshine duration and maximum temperature have a significant influence on physical activity levels.

Exercise for depression

BACKGROUND

Depression is a common and important cause of morbidity and mortality worldwide. Depression is commonly treated with antidepressants and/or psychotherapy, but some people may prefer alternative approaches such as exercise. There are a number of theoretical reasons why exercise may improve depression.

OBJECTIVES

To determine the effectiveness of exercise in the treatment of depression.

SEARCH STRATEGY

We searched Medline, Embase, Sports Discus, PsycLIT, the Cochrane Controlled Trials Register, and the Cochrane Database of Systematic Reviews for eligible studies. In addition, we hand-searched several relevant journals, contacted experts in the field, searched bibliographies of retrieved articles, and performed citation searches of identified studies. We also searched www.controlled-trials.com.

SELECTION CRITERIA

Randomised controlled trials in which exercise was compared to standard treatment, no treatment or a placebo treatment in adults (aged 18 and over) with depression, as defined by trial authors. We excluded trials of post-natal depression.

DATA COLLECTION AND ANALYSIS

We calculated effect sizes for each trial using Cohen's method and a standardised mean difference (SMD) for the overall pooled effect, using a random effects model. Where trials used a number of different tools to assess depression, we included the main outcome measure only in the meta-analysis.

MAIN RESULTS

Twenty-eight trials fulfilled our inclusion criteria, of which 25 provided data for meta-analyses. Randomisation was adequately concealed in a minority of studies, most did not use intention to treat analyses and most used self-reported symptoms as outcome measures. For the 23 trials (907 participants) comparing exercise with no treatment or a control intervention, the pooled SMD was -0.82 (95% CI -1.12, -0.51), indicating a large clinical effect. However, when we included only the three trials with adequate allocation concealment and intention to treat analysis and blinded outcome assessment, the pooled SMD was -0.42 (95% CI -0.88, 0.03) i.e. moderate, non-significant effect. The effect of exercise was not significantly different from that of cognitive therapy. There was insufficient data to determine risks and costs.

AUTHORS' CONCLUSIONS

Exercise seems to improve depressive symptoms in people with a diagnosis of depression, but when only methodologically robust trials are included, the effect sizes are only moderate and not statistically significant. Further, more methodologically robust trials should be performed to obtain more accurate estimates of effect sizes, and to determine risks and costs. Further systematic reviews could be performed to investigate the effect of exercise in people with dysthymia who do not fulfil diagnostic criteria for depression.

Evidence-based clinical guidelines: a new system to better determine true strength of recommendation

RATIONALE, AIMS AND OBJECTIVES

Clinical practice guidelines often grade the 'strength' of their recommendations according to the robustness of the supporting research evidence. The existing methodology does not allow the strength of recommendation (SOR) to be upgraded for recommendations for which randomized controlled trials are impractical or unethical. The purpose of this study was to develop a new method of determining SOR, incorporating both research evidence and expert opinion.

METHODS

A Delphi technique was employed to produce 10 recommendations for the role of exercise therapy in the management of osteoarthritis of the hip or knee. The SOR for each recommendation was determined by the traditional method, closely linked to the category of research evidence found on a systematic literature search, and on a visual analogue scale (VAS). Recommendations were grouped A-D according to the traditional SOR allocated and the mean VAS calculated. Difference across the groups was assessed by one-way ANOVA variance analysis.

RESULTS

Mean VAS scores for the traditional SOR groups A-D and one proposition which was 'not recommended' showed significant linearity on one-way ANOVA. However, certain recommendations which, for practical reasons, could not assessed in randomized controlled trials and therefore could not be recommended strongly by the traditional methodology, were allocated a strong recommendation by VAS.

CONCLUSIONS

This new system of grading strength of SOR is less constrained than the traditional methodology and offers the advantage of allowing SOR for procedures which cannot be assessed in RCTs for practical or ethical reasons to be upgraded according to expert opinion.

Evidence-based recommendations for the role of exercise in the management of osteoarthritis of the hip or knee--the MOVE consensus

OBJECTIVES

Exercise is an effective and commonly prescribed intervention for lower limb osteoarthritis (OA). Many unanswered questions remain, however, concerning the practical delivery of exercise therapy. We have produced evidence-based recommendations to guide health-care practitioners.

METHODS

A multidisciplinary guideline development group was formed from representatives of professional bodies to which OA is of relevance and other interested parties. Each participant contributed up to 10 propositions describing key clinical points regarding exercise therapy for OA of the hip or knee. Ten final recommendations were agreed by the Delphi technique. The research evidence for each was determined. A literature search was undertaken in the Medline, PubMed, EMBASE, PEDro, CINAHL and Cochrane databases. The methodological quality of each retrieved publication was assessed. Outcome data were abstracted and effect sizes calculated. The evidence for each recommendation was assessed and expert consensus highlighted by the allocation of two categories: (1) strength of evidence and (2) strength of recommendation.

RESULTS

The first round of the Delphi process produced 123 propositions. This was reduced to 10 after four rounds. These related to aerobic and strengthening exercise, group versus home exercise, adherence, contraindications and predictors of response. The literature search identified 910 articles; 57 intervention trials relating to knee OA, 9 to hip OA and 73 to adherence. The evidence to support each proposition is presented.

CONCLUSION

These are the first recommendations for exercise in hip and knee OA to clearly differentiate research evidence and expert opinion. Gaps in the literature are identified and issues requiring further study highlighted.

Economics of infection at the extremes of age

People are more vulnerable to infection at the extremes of age for a variety of reasons, the most important being that they are more likely to be in hospital in a crowded ward environment and to be at risk from hospital acquired infection. Recognition of this increased vulnerability to infection should be accompanied by equal emphasis on their increased susceptibility to nosocomial disease arising from the diagnosis or treatment of infection. An economic evaluation of infection at the extremes of age should include an assessment of need made in terms of the capacity of patients to benefit from investigation or treatment. Benefits should not be confused with treatment effects such as reduction in pyrexia or correction of other physiological abnormalities. Ideally benefits should be quantified in a manner which allows comparison with the cost-effectiveness of other uses of health care resources. In order to achieve this aim clinicians must understand the economic terms opportunity cost and marginal cost-effectiveness. These terms are defined in general terms and then applied to examples of investigation, prevention and treatment of infection at the extremes of age.