Alecia Nickless

Validation of Global Evapotranspiration Product (MOD16) using Flux Tower Data in the African Savanna, South Africa

Globally, water is an important resource required for the survival of human beings. Water is a scarce resource in the semi-arid environments, including South Africa. In South Africa, several studies have quantified evapotranspiration (ET) in different ecosystems at a local scale. Accurate spatially explicit information on ET is rare in the country mainly due to lack of appropriate tools. In recent years, a remote sensing ET product from the MODerate Resolution Imaging Spectrometer (MOD16) has been developed. However, its accuracy is not known in South African ecosystems. The objective of this study was to validate the MOD16 ET product using data from two eddy covariance flux towers, namely; Skukuza and Malopeni installed in a savanna and woodland ecosystem within the Kruger National Park, South Africa. Eight day cumulative ET data from the flux towers was calculated to coincide with the eight day MOD16 products over a period of 10 years from 2000 to 2010. The Skukuza flux tower results showed inconsistent comparisons with MOD16 ET. The Malopeni site achieved a poorer comparison with MOD16 ET compared to the Skukuza, and due to a shorter measurement period, data validation was performed for 2009 only. The inconsistent comparison of MOD16 and flux tower-based ET can be attributed to, among other things, the parameterization of the Penman-Monteith model, flux tower measurement errors, and flux tower footprint vs.

Screening and brief intervention for obesity in primary care: a parallel, two-arm, randomised trial.

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The effects of improving sleep on mental health (OASIS): a randomised controlled trial with mediation analysis

Summary Background Sleep difficulties might be a contributory causal factor in the occurrence of mental health problems. If this is true, improving sleep should benefit psychological health. We aimed to determine whether treating insomnia leads to a reduction in paranoia and hallucinations. Methods We did this single-blind, randomised controlled trial (OASIS) at 26 UK universities. University students with insomnia were randomly assigned (1:1) with simple randomisation to receive digital cognitive behavioural therapy (CBT) for insomnia or usual care, and the research team were masked to the treatment. Online assessments took place at weeks 0, 3, 10 (end of therapy), and 22. The primary outcome measures were for insomnia, paranoia, and hallucinatory experiences. We did intention-to-treat analyses. The trial is registered with the ISRCTN registry, number ISRCTN61272251. Findings Between March 5, 2015, and Feb 17, 2016, we randomly assigned 3755 participants to receive digital CBT for insomnia (n=1891) or usual practice (n=1864). Compared with usual practice, the sleep intervention at 10 weeks reduced insomnia (adjusted difference 4·78, 95% CI 4·29 to 5·26, Cohens d=1·11; p<0·0001), paranoia (−2·22, −2·98 to −1·45, Cohens d=0·19; p<0·0001), and hallucinations (−1·58, −1·98 to −1·18, Cohens d=0·24; p<0·0001). Insomnia was a mediator of change in paranoia and hallucinations. No adverse events were reported. Interpretation To our knowledge, this is the largest randomised controlled trial of a psychological intervention for a mental health problem. It provides strong evidence that insomnia is a causal factor in the occurrence of psychotic experiences and other mental health problems. Whether the results generalise beyond a student population requires testing. The treatment of disrupted sleep might require a higher priority in mental health provision. Funding Wellcome Trust.

Retrieval of Savanna Vegetation Canopy Height from ICESat-GLAS Spaceborne LiDAR With Terrain Correction

Light detection and ranging (LiDAR) remote sensing enables accurate estimation and monitoring of vegetation structural properties. Airborne and spaceborne LiDAR is known to provide reliable information on terrain elevation and forest canopy height over closed forests. However, it has rarely been used to characterize savannas, which have a complex structure of trees coexisting with grasses. This letter presents the first validation of spaceborne Ice Cloud and land Elevation Satellite Geoscience Laser Altimeter System (GLAS) full-waveform data to retrieve savanna vegetation canopy height that uses field data specifically collected within the GLAS footprints. Two methods were explored in the Kruger National Park, South Africa: one based on the Level 2 Global Land Surface Altimetry Data product and the other using Level 1A Global Altimetry Data (GLA01) with terrain correction. Both methods use Gaussian decomposition of the full waveform. Airborne LiDAR (AL) was also used to quantify terrain variability (slope) and canopy height within the GLAS footprints. The canopy height retrievals were validated with field observations in 23 GLAS footprints and show that the direct method works well over flat areas (Pearson correlation coefficient r = 0.70, , and n = 8 for GLA01) and moderate slopes (r = 0.68, , and n = 9 for GLA01). Over steep slopes in the footprint, however, the retrievals showed no significant correlation and required a statistical correction method to remove the effect of terrain variability on the waveform extent. This method improved the estimation accuracy of maximum vegetation height with correlations (R2 = 0.93, , and n = 6 using the terrain index (g) generated from AL data and R2 = 0.91,, and n = 6 using the GLAS returned waveform width parameter). The results suggest that GLAS can provide savanna canopy height estimations in complex tree/grass plant communities.

Methods to determine the impact of rainfall on fuels and burned area in southern African savannas

In southern African savannas, grass production, and therefore the annual extent of fire, is highly dependent on rainfall. This response has repeatedly been noted in the literature but authors used different input variables and modelling approaches and the results are not comparable. Using long-term fire occurrence data from six protected areas in southern Africa we tested various methods for determining the relationship between antecedent rainfall and burned area. The types of regression model, the most appropriate index of accumulated rainfall, and the period over which to calculate annual burned area were all investigated. The importance of accumulating rainfall over more than one growing season was verified in all parks – improving the accuracy of the models by up to 30% compared with indices that only used the previous year’s rainfall. Up to 56% of the variance in burned area between years could be explained by an 18-month accumulated rainfall index. Linear models and probit models performed equally well. The method suggested in this paper can be applied across southern Africa. This will improve our understanding of the drivers of interannual variation in burned area in this globally important fire region.

Stabilising sleep for patients admitted at acute crisis to a psychiatric hospital (OWLS): an assessor-blind pilot randomised controlled trial.

Background When patients are admitted onto psychiatric wards, sleep problems are highly prevalent. We carried out the first trial testing a psychological sleep treatment at acute admission (Oxford Ward sLeep Solution, OWLS). Methods This assessor-blind parallel-group pilot trial randomised patients to receive sleep treatment at acute crisis [STAC, plus standard care (SC)], or SC alone (1 : 1). STAC included cognitive–behavioural therapy (CBT) for insomnia, sleep monitoring and light/dark exposure for circadian entrainment, delivered over 2 weeks. Assessments took place at 0, 2, 4 and 12 weeks. Feasibility outcomes assessed recruitment, retention of participants and uptake of the therapy. Primary efficacy outcomes were the Insomnia Severity Index and Warwick–Edinburgh Mental Wellbeing Scale at week 2. Analyses were intention-to-treat, estimating treatment effect with 95% confidence intervals. Results Between October 2015 and July 2016, 40 participants were recruited (from 43 assessed eligible). All participants offered STAC completed treatment (mean sessions received = 8.6, s.d. = 1.5). All participants completed the primary end point. Compared with SC, STAC led to large effect size (ES) reductions in insomnia at week 2 (adjusted mean difference −4.6, 95% CI −7.7 to −1.4, ES −0.9), a small improvement in psychological wellbeing (adjusted mean difference 3.7, 95% CI −2.8 to 10.1, ES 0.3) and patients were discharged 8.5 days earlier. One patient in the STAC group had an adverse event, unrelated to participation. Conclusions In this challenging environment for research, the trial was feasible. Therapy uptake was high. STAC may be a highly effective treatment for sleep disturbance on wards with potential wider benefits on wellbeing and admission length.

30-year trends in admission rates for encephalitis in children in England and effect of improved diagnostics and measles-mumps-rubella vaccination: a population-based observational study

BACKGROUND Encephalitis is a serious neurological disorder, yet data on admission rates for all-cause childhood encephalitis in England are scarce. We aimed to estimate admission rates for childhood encephalitis in England over 33 years (1979-2011), to describe trends in admission rates, and to observe how these rates have varied with the introduction of vaccines and improved diagnostics. METHODS We did a retrospective analysis of hospital admission statistics for encephalitis for individuals aged 0-19 years using national data from the Hospital Inpatient Enquiry (HIPE, 1979-85) and Hospital Episode Statistics (HES, 1990-2011). We analysed annual age-specific and age-standardised admission rates in single calendar years and admission rate trends for specified aetiologies in relation to introduction of PCR testing and measles-mumps-rubella (MMR) vaccination. We compared admission rates between the two International Classification of Diseases (ICD) periods, ICD9 (1979-94) and ICD10 (1995-2011). FINDINGS We found 16 571 encephalitis hospital admissions in the period 1979-2011, with a mean hospital admission rate of 5·97 per 100 000 per year (95% CI 5·52-6·41). Hospital admission rates declined from 1979 to 1994 (ICD9; annual percentage change [APC] -3·30%; 95% CI -2·88 to -3·66; p<0·0001) and increased between 1995 and 2011 (ICD10; APC 3·30%; 2·75-3·85; p<0·0001). Admissions for measles decreased by 97% (from 0·32 to 0·009) and admissions for mumps encephalitis decreased by 98% (from 0·60 to 0·01) after the introduction of the two-dose MMR vaccine. Hospital admission rates for encephalitis of unknown aetiology have increased by 37% since the introduction of PCR testing. INTERPRETATION Hospital admission rates for all-cause childhood encephalitis in England are increasing. Admissions for measles and mumps encephalitis have decreased substantially. The numbers of encephalitis admissions without a specific diagnosis are increasing despite availability of PCR testing, indicating the need for strategies to improve aetiological diagnosis in children with encephalitis. FUNDING None.

Evaluation of Clear-Sky Incoming Radiation Estimating Equations Typically Used in Remote Sensing Evapotranspiration Algorithms

Net radiation is a key component of the energy balance, whose estimation accuracy has an impact on energy flux estimates from satellite data. In typical remote sensing evapotranspiration (ET) algorithms, the outgoing shortwave and longwave components of net radiation are obtained from remote sensing data, while the incoming shortwave ( S ՝ ) and longwave ( L ) components are typically estimated from weather data using empirical equations. This study evaluates the accuracy of empirical equations commonly used in remote sensing ET algorithms for estimating S ՝ and L radiation. Evaluation is carried out through comparison of estimates and observations at five sites that represent different climatic regions from humid to arid. Results reveal (1) both S and L ՝ estimates from all evaluated equations well correlate with observations (R 2 ≥ 0.92),

Mitigating the effect of persistent postnatal depression on child outcomes through an intervention to treat depression and improve parenting: a randomised controlled trial

BACKGROUND Maternal postnatal depression occurs following 10-15% of births and is associated with a range of negative child outcomes. Risks to children are particularly increased when postnatal depression is persistent. We aimed to examine whether a parenting video-feedback therapy (VFT) intervention versus a control treatment of progressive muscle relaxation (PMR), both added to cognitive behavioural therapy (CBT) for persistent postnatal depression, would lead to improved child outcomes at age 2 years. METHODS In this two-arm, parallel-design, individually randomised controlled trial, we recruited a community sample of women aged 18 years or older living within 50 miles of Oxford, UK, between 4·5 and 9·0 months post partum. All participants met diagnostic criteria for current major depressive disorder that had persisted for at least 3 months and had infants at 35 or more weeks of gestation, with a birthweight of 2000 g or greater, and without serious neonatal complications. Through a centralised service, women were randomly assigned by use of a minimisation algorithm, to receive either VFT or PMR, balanced for child sex, temperament, age, socioeconomic status, and severity of depression. Both groups also received CBT for depression. Primary outcomes were child cognitive development, language development, behaviour problems, and attachment security at age 2 years. There were 11 home-based treatment sessions before child age 1 year, followed by two booster sessions in the second year. Assessors were masked to treatment group allocation. All analyses were done according to the intention-to-treat principle. This trial is registered with the ISRCTN registry, number ISRCTN07336477. FINDINGS Between March 18, 2011, and Dec 9, 2013, we randomly assigned 144 women, 72 to each group. Primary outcome data were available for 62-64 (86-89%) VFT and 67-68 (93-94%) PMR participants. There were no group differences in child outcome (cognitive development, adjusted difference -1·01 [95% CI -5·11 to 3·09], p=0·63; language development, 1·33 [-4·16 to 6·82], p=0·63; behaviour problems, -1·77 [-4·39 to 0·85], p=0·19; attachment security, 0·02 [-0·06 to 0·10], p=0·58), with both groups achieving scores similar to non-clinical norms on all outcomes. There were six serious adverse events: five in the VFT group (in two participants) and one in the PMR group. None was treatment-related. INTERPRETATION The effect of persistent postnatal depression on children is a major public health issue. For both treatment groups there was sustained remission from depression, and child development outcomes were in the normal range. The precise mechanisms accounting for the observed positive child outcomes cannot be ascertained from this study. FUNDING Wellcome Trust.

Automated psychological therapy using immersive virtual reality for treatment of fear of heights: a single-blind, parallel-group, randomised controlled trial

Summary Background Engaging, interactive, and automated virtual reality (VR) treatments might help solve the unmet needs of individuals with mental health disorders. We tested the efficacy of an automated cognitive intervention for fear of heights guided by an avatar virtual coach (animated using motion and voice capture of an actor) in VR and delivered with the latest consumer equipment. Methods We did a randomised trial of automated VR versus usual care. We recruited adults aged older than 18 years with a fear of heights by radio advertisements in Oxfordshire, UK. We diagnosed fear of heights if participants scored more than 29 on the Heights Interpretation Questionnaire (HIQ). We randomly allocated participants by computer in a 1:1 ratio to either automated VR delivered in roughly six 30-min sessions administered about two to three times a week over a 2-week period (intervention group) or to usual care (control group). Randomisation was stratified by severity of fear of heights. The research team, who were unaware of the random allocation, administered three fear-of-height assessments, at baseline (0 weeks), at the end of treatment (2 weeks), and at follow-up (4 weeks). The primary outcome measure was HIQ score (range 16–80, with higher scores indicating greater severity). This trial is registered with the ISRCTN registry, number ISRCTN11898283. Findings Between Nov 25, 2017, and Feb 27, 2018, 100 individuals were enrolled and underwent randomisation, of whom 49 were assigned to the VR treatment group and 51 to the control group. All participants completed the 4-week follow-up. The mean total treatment time in VR was 124·43 min (SD 34·23). Compared with participants in the control group, the VR treatment reduced fear of heights at the end of treatment (mean change score −24·5 [SD 13·1] in the VR group vs −1·2 [7·3] in the control group; adjusted difference −24·0, 95% CI −27·7 to −20·3; Cohens d=2·0; p<0·0001). The benefit was maintained at follow-up (mean change score −25·1 [SD 13·9] in the VR group vs −1·5 [7·8] in the control group; adjusted difference −24·3, 95% CI −27·9 to −20·6; Cohens d=2·0; p<0·0001). The number needed to treat to at least halve the fear of heights was 1·3. No adverse events were reported. Interpretation Psychological therapy delivered automatically by a VR coach can produce large clinical benefits. Evidence-based VR treatments have the potential to greatly increase treatment provision for mental health disorders. Funding Oxford VR, and the National Institute of Health Research Oxford Health Biomedical Research Centre.