River monitoring from satellite radar altimetry in the Zambezi River basin

Satellite radar altimetry can be used to monitor surface water levels from space. While current and past altimetry missions were designed to study oceans, retracking the waveforms returned over land allows data to be retrieved for smaller water bodies or narrow rivers. The objective of this study is the assessment of the potential for river monitoring from radar altimetry in terms of water level and discharge in the Zambezi River basin. Retracked Envisat altimetry data were extracted over the Zambezi River basin using a detailed river mask based on Landsat imagery. This allowed for stage measurements to be obtained for rivers down to 80m wide with an RMSE relative to in situ levels of 0.32 to 0.72m at different locations. The altimetric levels were then converted to discharge using three different methods adapted to different data-availability scenarios: first with an in situ rating curve available, secondly with one simultaneous field measurement of cross-section and discharge, and finally with only historical discharge data available. For the two locations at which all three methods could be applied, the accuracies of the different methods were found to be comparable, with RMSE values ranging from 4.1 to 6.5% of the mean annual in situ gauged amplitude for the first method and from 6.9 to 13.8% for the second and third methods. The precision obtained with the different methods was analyzed by running Monte Carlo simulations and also showed comparable values for the three approaches with standard deviations found between 5.7 and 7.2% of the mean annual in situ gauged amplitude for the first method and from 8.7 to 13.0% for the second and third methods

Speech and language therapy versus placebo or no intervention for speech problems in Parkinson's disease

Parkinson's disease patients commonly suffer from speech and vocal problems including dysarthric speech, reduced loudness and loss of articulation. These symptoms increase in frequency and intensity with progression of the disease). Speech and language therapy (SLT) aims to improve the intelligibility of speech with behavioural treatment techniques or instrumental aids

Longer Electromechanical Delay Impairs Hamstrings Explosive Force versus Quadriceps

Introduction Explosive neuromuscular performance refers to the ability to rapidly increase force in response to neuromuscular activation. The lower explosive force production of the hamstrings relative to the quadriceps could compromise knee joint stability and increase the risk of anterior cruciate ligament injury. However, the time course of the rise in explosive force of the hamstrings and quadriceps from their initial activation, and thus the explosive hamstrings-to-quadriceps (H/Q) force ratio, has not been documented.Methods The neuromuscular performance of 20 untrained males was assessed during a series of isometric knee flexion and extension contractions, with force and surface EMG of the hamstrings and quadriceps recorded during explosive and maximum voluntary contractions. Hamstrings force was expressed relative to quadriceps force to produce hamstring-to-quadriceps ratios of explosive H/Q force and H/Q maximum voluntary force. For the explosive contractions, agonist electromechanical delay (EMD), agonist and antagonist neural activation were assessed.Results The quadriceps was 79% stronger than the hamstrings, but quadriceps explosive force was up to 480% greater than the hamstrings from 25 to 50 ms after first activation. Consequently, the explosive H/Q force ratio was very low at 25 and 50 ms (0%–17%) and significantly different from H/Q maximum voluntary force ratio (56%). Hamstrings EMD was 95% greater than quadriceps EMD (44.0 vs 22.6 ms), resulting in a 21-ms later onset of force in the hamstrings that appeared to explain the low explosive H/Q force ratio in the early phase of activation.Conclusions Prolonged hamstrings EMD appears to impair early phase (0–50 ms) explosive force production relative to the quadriceps and may render the knee unstable and prone to anterior cruciate ligament injury during this period

Sex differences in the association between salivary telomere length and multimorbidity within the US Health & Retirement Study

Background: Telomere length is associated with several physical and mental health conditions, but whether it is a marker of multimorbidity is unclear. We investigated associations between telomere length and multimorbidity by sex. Methods: Data from adults (N = 5,495) aged ≥50 years were taken from the US Health and Retirement Study (2008–14). Telomere length was measured in 2008 from salivary samples. The cross-sectional associations between telomere length and eight chronic health conditions were explored using logistic regression, adjusting for confounders and stratified by sex. Logistic, ordinal and multinomial regression models were calculated to explore relationships between telomere length and multimorbidity (using a binary variable and a sum of the number of health conditions) and the type of multimorbidity (no multimorbidity, physical multimorbidity, or multimorbidity including psychiatric problems). Using multilevel logistic regression, prospective relationships between telomere length and incident multimorbidity were also explored. Results: In cross-sectional analyses, longer telomeres were associated with reduced likelihood of lung disease and psychiatric problems among men, but not women. Longer telomeres were associated with lower risk of multimorbidity that included psychiatric problems among men (OR=0.521, 95% CI: 0.284 to 0.957), but not women (OR=1.188, 95% CI: 0.771 to 1.831). Prospective analyses suggested little association between telomere length and the onset of multimorbidity in men (OR=1.378, 95% CI: 0.931 to 2.038) nor women (OR=1.224, 95% CI: 0.825 to 1.815). Conclusions: Although telomere length does not appear to be a biomarker of overall multimorbidity, further exploration of the relationships is merited particularly for multimorbidity including psychiatric conditions among men

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Thesis (Ed.M.)--Boston Universit

Toward a Framework for Outcome-Based Analytical Performance Specifications: A Methodology Review of Indirect Methods for Evaluating the Impact of Measurement Uncertainty on Clinical Outcomes

Background: For medical tests that have a central role in clinical decision-making, current guidelines advocate outcome-based analytical performance specifications. Given that empirical (clinical-trial style) analyses are often impractical or unfeasible in this context, the ability to set such specifications is expected to rely on indirect studies to calculate the impact of test measurement uncertainty on downstream clinical, operational and economic outcomes. Currently however, a lack of awareness and guidance concerning available alternative indirect methods is limiting the production of outcome-based specifications. Our aim therefore was to review available indirect methods and present an analytical framework to inform future outcome-based performance goals. Content: A methodology review consisting of database searches and extensive citation tracking was conducted to identify studies using indirect methods to incorporate or evaluate the impact of test measurement uncertainty on downstream outcomes (including clinical accuracy, clinical utility and/or costs). Eighty-two studies were identified, most of which evaluated the impact of imprecision and/or bias on clinical accuracy. A common analytical framework underpinning the various methods was identified, consisting of three key steps: (1) calculation of “true” test values; (2) calculation of measured test values (incorporating uncertainty); and (3) calculation of the impact of discrepancies between (1) and (2) on specified outcomes. A summary of the methods adopted is provided, and key considerations discussed. Conclusions: Various approaches are available for conducting indirect assessments to inform outcome-based performance specifications. This study provides an overview of methods and key considerations to inform future studies and research in this area

Detection of Visual Field Loss in Pituitary Disease: Peripheral Kinetic Versus Central Static.

Visual field assessment is an important clinical evaluation for eye disease and neurological injury. We evaluated Octopus semi-automated kinetic peripheral perimetry (SKP) and Humphrey static automated central perimetry for detection of neurological visual field loss in patients with pituitary disease. We carried out a prospective cross-sectional diagnostic accuracy study comparing Humphrey central 30-2 SITA threshold programme with a screening protocol for SKP on Octopus perimetry. Humphrey 24-2 data were extracted from 30-2 results. Results were independently graded for presence/absence of field defect plus severity of defect. Fifty patients (100 eyes) were recruited (25 males and 25 females), with mean age of 52.4 years (SD = 15.7). Order of perimeter assessment (Humphrey/Octopus first) and order of eye tested (right/left first) were randomised. The 30-2 programme detected visual field loss in 85%, the 24-2 programme in 80%, and the Octopus combined kinetic/static strategy in 100% of eyes. Peripheral visual field loss was missed by central threshold assessment. Qualitative comparison of type of visual field defect demonstrated a match between Humphrey and Octopus results in 58%, with a match for severity of defect in 50%. Tests duration was 9.34 minutes (SD = 2.02) for Humphrey 30-2 versus 10.79 minutes (SD = 4.06) for Octopus perimetry. Octopus semi-automated kinetic perimetry was found to be superior to central static testing for detection of pituitary disease-related visual field loss. Where reliant on Humphrey central static perimetry, the 30-2 programme is recommended over the 24-2 programme. Where kinetic perimetry is available, this is preferable to central static programmes for increased detection of peripheral visual field loss

Depressive symptoms, neuroticism and participation in breast and cervical cancer screening: cross-sectional and prospective evidence from UK Biobank

Objective: To assess the cross‐sectional and prospective associations between depressive symptoms, neuroticism, and participation in breast and cervical screening in the UK. Methods: Women in the UK Biobank cohort with complete data who were eligible for breast cancer screening (aged 50‐70 years, N = 143 461) and/or cervical screening (<65 years, N = 141 753) at baseline recruitment (2006‐2010) and those with follow‐up data (2014‐2019) were identified (N = 11 050 and N = 9780 for breast and cervical screening). Depressive symptoms and neuroticism were self‐reported at baseline (range 0‐12 with higher scores reflecting greater severity). Primary outcomes were reporting being up to date with breast and cervical screening. For prospective analyses, patterns of screening participation from baseline to follow‐up were identified. Logistic regression was used to analyse associations, adjusted for potential confounding factors. Results: More severe depressive symptoms were associated with reduced likelihood of breast (OR = 0.960, 95% CI: 0.950,0.970) and cervical (OR = 0.958, 95% CI: 0.950,0.966) screening participation, in cross‐sectional analyses. Higher neuroticism scores were associated with reduced cervical screening participation, but the opposite was found for breast cancer screening. Examination of individual neuroticism items revealed that anxiety and worry were associated with increased breast screening. At follow‐up, higher baseline depressive symptoms were related to decreased cervical screening (OR = 0.955, 95% CI: 0.913,0.999), but not with breast screening. Conclusions: More severe depressive symptoms may be a barrier for breast and cervical screening and could be an indicator for more proactive strategies to improve uptake

PREP2 Algorithm Predictions Are Correct at 2 Years Poststroke for Most Patients

Background. The PREP2 algorithm combines clinical and neurophysiological measures to predict upper-limb (UL) motor outcomes 3 months poststroke, using 4 prediction categories based on Action Research Arm Test (ARAT) scores. The algorithm was accurate at 3 months for 75% of participants in a previous validation study. Objective. This study aimed to evaluate whether PREP2 predictions made at baseline are correct 2 years poststroke. We also assessed whether patients’ UL performance remained stable, improved, or worsened between 3 months and 2 years after stroke. Methods. This is a follow-up study of 192 participants recruited and assessed in the original PREP2 validation study. Participants who completed assessments 3 months poststroke (n = 157) were invited to complete follow-up assessments at 2 years poststroke for the present study. UL outcomes were assessed with the ARAT, upper extremity Fugl-Meyer Scale, and Motor Activity Log. Results. A total of 86 participants completed 2-year follow-up assessments in this study. PREP2 predictions made at baseline were correct for 69/86 (80%) participants 2 years poststroke, and PREP2 UL outcome category was stable between 3 months and 2 years poststroke for 71/86 (83%). There was no difference in age, stroke severity, or comorbidities among patients whose category remained stable, improved, or deteriorated. Conclusions. PREP2 algorithm predictions made within days of stroke are correct at both 3 months and 2 years poststroke for most patients. Further investigation may be useful to identify which patients are likely to improve, remain stable, or deteriorate between 3 months and 2 years

Peer victimisation in early childhood; observations of participant roles and sex differences

During middle childhood and adolescence, victimisation appears to be a group process involving different participant roles. However, peer reports with younger children (four to six years old) have failed to identify the participant roles of assistant (to the bully) reinforcers or defenders with much reliability. This may be because peer victimisation is a more dyadic process among younger children (behavioural reality), or because of limitations in young children’s cognitive capacity to identify these behaviours (cognitive limitations). The findings of an observational study which examined the group nature of peer victimisation among young children are presented. Observations were made of 56 children aged four and five years using time sampling during free play at school (totalling 43.5 h of observation). Records were made of their behaviour when an onlooker witnessed aggression by others, and also of others’ behaviour when they were being aggressive or being victimised. Although children other than the aggressor and target were present in nearly two thirds of the episodes of peer victimisation observed, few exhibited behavioural responses in line with the assistant, reinforcer or defender roles. This supports the behavioural reality rather than the cognitive limitations explanation. Sex differences were observed in types of aggression displayed by children, with boys more likely than girls to be physically aggressive. Children were less likely to be aggressive to other-sex peers and were most likely to be victimised by children of the same sex as them. There were also sex differences in children’s onlooker behaviour. The implications for our understanding of the development of peer victimisation and bullying in children are discussed