Impact of COVID-19 on the veteran population: evidence from the Trends in Scottish Veterans Health study.

INTRODUCTION: There have been few epidemiological studies on the impact of the SARS-CoV-2 (COVID-19) pandemic on the veteran population, other than on specific aspects such as mental health, and none in the UK. We used data from the Trends in Scottish Veterans Health cohort to explore the risk of hospitalisation and death associated with COVID-19 in veterans resident in Scotland in comparison with matched non-veterans. METHODS: Retrospective cohort study of 71 000 veterans and a comparison group of 230 000 non-veterans matched for age, sex and geography, using Cox proportional hazard analysis to explore the risk of hospitalisation with COVID-19 and COVID-19-associated death overall and by birth cohort, sex and length of military service. RESULTS: Between 1 January 2020 and 31 December 2021, 564 (0.79%) veterans had been hospitalised with COVID-19 compared with 1728 (0.75%) non-veterans. The Cox model showed no significant difference overall, HR 0.99, 95% CIs 0.90 to 1.11, p=0.800. Subgroup analysis showed increased risk in older, short-serving (<20 weeks) Early Service Leavers (ESL). There was no overall difference in COVID-19-associated deaths, HR 0.99, 95% CI 0.79 to 1.23, p=0.993, but subgroup analysis showed a non-significant reduced risk of death in veterans aged 61-70 years, and a 38% higher risk in veterans aged over 70 years which almost reached statistical significance, p=0.054. This was only partially explained by socioeconomic factors and common comorbidities, although we had no data on domestic circumstances or care home residence. CONCLUSIONS: Overall, military service was not a risk factor for either hospitalisation or death associated with COVID-19. Older ESLs were at increased risk compared with non-veterans, but military service is unlikely to have been causal. The risk of death was increased in the oldest veterans and further studies are needed to explain this once census data become available for linkage.

Tree water uptake patterns across the globe.

Plant water uptake from the soil is a crucial element of the global hydrological cycle and essential for vegetation drought resilience. Yet, knowledge of how the distribution of water uptake depth (WUD) varies across species, climates, and seasons is scarce relative to our knowledge of aboveground plant functions. With a global literature review, we found that average WUD varied more among biomes than plant functional types (i.e. deciduous/evergreen broadleaves and conifers), illustrating the importance of the hydroclimate, especially precipitation seasonality, on WUD. By combining records of rooting depth with WUD, we observed a consistently deeper maximum rooting depth than WUD with the largest differences in arid regions - indicating that deep taproots act as lifelines while not contributing to the majority of water uptake. The most ubiquitous observation across the literature was that woody plants switch water sources to soil layers with the highest water availability within short timescales. Hence, seasonal shifts to deep soil layers occur across the globe when shallow soils are drying out, allowing continued transpiration and hydraulic safety. While there are still significant gaps in our understanding of WUD, the consistency across global ecosystems allows integration of existing knowledge into the next generation of vegetation process models.

Combining PSII photochemistry and hydraulics improves predictions of photosynthesis and water use from mild to lethal drought.

Rising temperatures and increases in drought negatively impact the efficiency and sustainability of both agricultural and forest ecosystems. Although hydraulic limitations on photosynthesis have been extensively studied, a solid understanding of the links between whole plant hydraulics and photosynthetic processes at the cellular level under changing environmental conditions is still missing, hampering our predictive power for plant mortality. Here, we examined plant hydraulic traits and CO2 assimilation rate under progressive water limitation by implementing Photosystem II (PSII) dynamics with a whole plant process model (TREES). The photosynthetic responses to plant water status were parameterized based on measurements of chlorophyll a fluorescence, gas exchange and water potential for Brassica rapa (R500) grown in a greenhouse under fully watered to lethal drought conditions. The updated model significantly improved predictions of photosynthesis, stomatal conductance and leaf water potential. TREES with PSII knowledge predicted a larger hydraulic safety margin and a decrease in percent loss of conductivity. TREES predicted a slower decrease in leaf water potential, which agreed with measurements. Our results highlight the pressing need for incorporating PSII drought photochemistry into current process models to capture cross-scale plant water dynamics from cell to whole plant level.

Increased risk of lower limb osteoarthritis among former professional soccer (football) players.

BACKGROUND: Soccer is a high-speed contact sport with risk of injury. Despite long-standing concern, evidence to date remains inconsistent as to the association between playing professional-level soccer and lifelong musculoskeletal consequences. AIMS: The objectives were to assess risk of osteoarthritis in former professional soccer players compared to matched general population controls, and subsequently assess associated musculoskeletal disorders which may contribute to, or result from, osteoarthritis-specifically meniscal injury and joint replacement. METHODS: We conducted a retrospective cohort study using national electronic health records (EHRs) on a cohort of 7676 former professional soccer players aged 40 or over at recruitment, matched on year of birth, sex (all male) and socio-economic status with 23 028 general population controls. Outcomes of interest were obtained by utilizing individual-level record linkage to EHRs from general hospital inpatient and day-case admissions. RESULTS: Compared to controls, former soccer players showed a greater risk of hospital admission for osteoarthritis (hazard ratio [HR] 3.01; 95% confidence interval [CI] 2.80-3.25; P < 0.001). This increased risk appeared age dependant, normalizing over age 80 years and reflective of increased risk of lower limb osteoarthritis. Further, risk of hospital admissions for meniscal injury (HR 2.73; 95% CI 2.42-3.08; P < 0.001) and joint replacement (HR 2.82; 95% CI 2.23-3.57; P < 0.001) were greater among former soccer players. CONCLUSIONS: We report an increased risk of lower limb osteoarthritis in former soccer players when compared with matched population controls. The results of this research add data in support of lower limb osteoarthritis among former soccer players representing a potential industrial injury.

Specialist epilepsy service input following an epilepsy related unscheduled care episode.

BACKGROUND: Emergency and unplanned epilepsy-related attendances are associated with an increased risk of subsequent death within 6 months. Although further work is required to provide a definitive explanation to account for these findings, in the interim it would seem reasonable that services are designed to ensure timely access and provide support at a time of greatest risk. We aim to determine the frequency of patients with epilepsy (PWE) accessing specialist neurology services following an epilepsy-related admission/unscheduled care episode. METHODS: Patients were included in the cohort if they had at least 1 prescription for an anti-seizure medication and at least one epilepsy-related admission, emergency department attendance, or outpatient neurology clinic attendance between January 2011 and November 2021. We evaluated the rate of any outpatient neurology clinic attendance in the subsequent 6 months following an epilepsy related unscheduled care episode. RESULTS: Of the 6,449 PWE included in the cohort, 4,465 were included for analysis. At the end of the follow up period less than 40% were accessing specialist services within 6 months of an episode of admission/ unscheduled care episode. Around a third (31.1%) of deaths occurred within 6 months of an epilepsy-related admission, and in the majority of cases patients were not seen by an epilepsy specialist in the period between discharge and death. The frequency of mental health comorbidity in PWE accessing unscheduled care remains very high with almost 80% having a diagnosis of either depression or anxiety. CONCLUSION: A significant proportion of PWE are not accessing specialist services in a timely manner following an episode of unscheduled care. Such provision may potentially provide an opportunity to reduce epilepsy related mortality by altering antiseizure medication doses and considering reversible factors associated with poor outcomes in PWE, such as poor medication adherence.

The impact of the COVID-19 pandemic on a cohort of adults with epilepsy.

OBJECTIVES: The aim of this study was to assess the direct and indirect impacts of the COVID-19 pandemic on adults with epilepsy in Glasgow. METHODS: We used routinely collected data for a previously identified cohort of patients with epilepsy to evaluate access to scheduled and unscheduled care with quarterly rates of inpatient admissions, outpatient attendance and accident & emergency attendance calculated. Anti-seizure medication prescribing and persistence, incidence of anxiety and depression and deaths for a cohort of patients with epilepsy was evaluated prior to the pandemic in comparison to during the pandemic, from 2015 to 2021. RESULTS: All-cause mortality and epilepsy related mortality showed a statistically significant reduction during the pandemic. Although overall rates of out-patient hospital attendance dropped during the early stages of the pandemic (and had not returned to pre-pandemic levels by the end of 2021) epilepsy-related services saw maintenance of patient contact as a result of a rapid adoption of telephone clinics. A significant decrease in overall mortality was observed in PWE during the pandemic compared to the pre-pandemic period. COVID-19 was the single commonest cause of death in PWE during the pandemic (61/453) and 160 patients (3.7%) had at least 1 admission to hospital for COVID-19. Anti-seizure medication (ASM) prescribing remained rates remained stable during the pandemic. During the pandemic an average of 38.8% of cohort patients were treated for depression and 16.3% for anxiety per quarter, 8.2% and 12.4% of whom had not been previously treated for these conditions respectively. CONCLUSION: We have shown that during a national lockdown, in the context of a pandemic, mortality in patients with epilepsy has reduced, while out-patient services were delivered remotely, primarily via the telephone. The reasons for this remain unclear but suggest that some of the excess mortality in people with epilepsy may be potentially avoidable by changes in lifestyle.

Evaluating the effects of minimum unit pricing in Scotland on the prevalence of harmful drinking: a controlled interrupted time series analysis.

OBJECTIVES: In May 2018, the Scottish Government introduced a minimum unit price (MUP) for alcohol of £0.50 (1 UK unit = 8 g ethanol) to reduce alcohol consumption, particularly among people drinking at harmful levels. This study aimed to evaluate MUP's impact on the prevalence of harmful drinking among adults in Scotland. STUDY DESIGN: This was a controlled interrupted monthly time series analysis of repeat cross-sectional data collected via 1-week drinking diaries from adult drinkers in Scotland (N = 38,674) and Northern England (N = 71,687) between January 2009 and February 2020. METHODS: The primary outcome was the proportion of drinkers consuming at harmful levels (>50 [men] or >35 [women] units in diary week). The secondary outcomes included the proportion of drinkers consuming at hazardous (≥14-50 [men] or ≥14-35 [women] units) and moderate (<14 units) levels and measures of beverage preferences and drinking patterns. Analyses also examined the prevalence of harmful drinking in key subgroups. RESULTS: There was no significant change in the proportion of drinkers consuming at harmful levels (ß = +0.6 percentage points; 95% confidence interval [CI] = -1.1, +2.3) or moderate levels (ß = +1.4 percentage points; 95% confidence interval = -1.1, +3.8) after the introduction of MUP. The proportion consuming at hazardous levels fell significantly by 3.5 percentage points (95% CI = -5.4, -1.7). There were no significant changes in other secondary outcomes or in the subgroup analyses after correction for multiple testing. CONCLUSIONS: Introducing MUP in Scotland was not associated with reductions in the proportion of drinkers consuming at harmful levels but did reduce the prevalence of hazardous drinking. This adds to previous evidence that MUP reduced overall alcohol consumption in Scotland and consumption among those drinking above moderate levels.

A Long-term Follow-up of a Late Diagnosed Patient with Temple Syndrome - a Case Report.

Temple syndrome (TS) is a rare imprinting disorder, caused by alterations in the critical imprinted region 14q32 of chromosome 14. It is characterized by pre- and postnatal growth retardation, truncal hypotonia and facial dysmorphism in the neonatal period. We report a 18-year-old girl with a late diagnosis presenting all typical signs and symptoms of Temple syndrome - small for gestational age at birth, feeding difficulties, muscle hypotonia and delayed developmental milestones, central precocious puberty, truncal obesity and reduced growth. The patient is the second reported in the literature with signs of clinical and biochemical hyperandrogenism and the first treated with Dehydrocortisone®, with a good response. The clinical diagnosis of this patient was achieved after a long-term follow up at a single center of rare endocrine diseases, and a molecular genetics diagnosis of complete hypomethylation of 14q32 chromosome imprinting center (DLK/GTL2) was recently established. Growth hormone (GH) treatment was not given and although precocious puberty was treated in line with standard protocols, patient's final height remained below the target range. Increased awareness of Temple syndrome and timely molecular diagnosis enables improvement of clinical care of these patients as well as prevention of inherent metabolic consequences.

Dementia in Scottish military veterans: early evidence from a retrospective cohort study.

BACKGROUND: Few studies have examined whether UK military veterans are at an increased risk of dementia. We explored the risk of dementia in Scottish military veterans aged up to 73 years in comparison with people who have never served. METHODS: Retrospective cohort study of 78 000 veterans and 253 000 people with no record of service, matched for age, sex and area of residence, with up to 37 years follow-up, using Cox proportional hazard analysis to compare risk of dementia in veterans and non-veterans, overall and by subgroup. RESULTS: Dementia was recorded in 0.2% of both veterans and non-veterans overall, Cox proportional hazard ratio 0.98, 95% confidence interval (CI) 0.82-1.19, p = 0.879 (landmark age: 50 years), with no difference for men but increased risk in veteran women and Early Service Leavers. Post-traumatic stress disorder (PTSD) was associated with a higher risk of dementia in both veterans and non-veterans, although possibly to a lesser degree in veterans. A history of mood disorder was strongly associated with developing dementia, greater in veterans than in non-veterans, odds ratio 1.54, 95% CI 1.01-2.35, p = 0.045. CONCLUSIONS: There was no evidence to suggest that military service increased the risk of dementia, although this may change as the cohort ages. The well-documented association with PTSD shows no evidence of being stronger in veterans; by contrast, the association of mood disorder with dementia is much stronger in veterans. Healthcare providers should carefully assess the cognitive status of older veterans presenting with depressive illness in order to identify early dementia and ensure optimum management.

Hip and knee replacement as a proxy measure for lower limb osteoarthritis in Scottish military veterans.

INTRODUCTION: Physical activity is an important component of military training. Although injuries and musculoskeletal disorders are the most common cause of medical retirement from the Armed Forces, the long-term risk of lower limb osteoarthritis in veterans is unknown. We used data on hip and knee replacement in Scottish military veterans as a proxy measure. METHODS: Retrospective cohort study of 78 000 veterans born between 1945 and 1995 and a comparison group of 253 000 non-veterans, matched for age, sex and area of residence, followed up for up to 37 years, using survival analysis to examine the risk of hip and knee replacement. RESULTS: Veterans were significantly less likely to undergo hip replacement than non-veterans, Cox proportional HR 0.87, 95% CI 0.80 to 0.95, p<0.001. There was no significant difference between veterans and non-veterans in respect of knee replacement, HR 1.02, 95% CI 0.94 to 1.11, p=0.643, and there was no difference in the ages at which veterans and non-veterans underwent joint replacement. People who had served for longest in the military had similar risk to those with the shortest service. CONCLUSIONS: Based on the likelihood of undergoing joint replacement surgery in later life, we found no evidence of a positive association between military service and an increased risk of lower limb osteoarthritis.

Age at entry to UK military service and long-term mental health.

INTRODUCTION: It has been suggested that 'junior entry' to the UK Armed Forces (prior to age 17.5 years) increases the risk of adverse mental health outcomes. We used data from a large cohort of veterans to examine long-term mental health outcomes in veterans by age at entry to the UK Armed Forces, compared with non-veterans. METHODS: Retrospective cohort study of 78 157 veterans in Scotland, born between 1945 and 1995 and and 252 637 matched non-veterans, with up to 37 years follow-up, using Cox proportional hazard models to examine the association between veteran status and cumulative risk of major mental health disorder, stratified by birth cohort, and age at recruitment for the veterans. RESULTS: The risk of mental health disorder in the veterans increased with age at entry, ranging from HR 1.12, 95% CI 1.06 to 1.18, p<0.001 for junior entrants to HR 1.37, 95% CI 1.27 to 1.80, p<0.001 for those aged 20-25 years at entry. The pattern was most marked for veterans born before 1960, and age at recruitment had little impact in recent birth cohorts. Post-traumatic stress disorder accounted for most of the observed differences. Younger age at recruitment was associated with longer service, median 7.4 years (IQR 3.0-14.7) compared with 5.6 years (IQR 2.1-11.7) for entrants aged 20-25 years. CONCLUSION: We found no evidence that early recruitment is associated with adverse impact on long-term mental health. Paradoxically, it was veterans who entered service at age 20-25 years who demonstrated increased risk, although this attenuated in more recent birth cohorts.

The influence of increasing atmospheric CO2 , temperature, and vapor pressure deficit on seawater-induced tree mortality.

Increasing seawater exposure is killing coastal trees globally, with expectations of accelerating mortality with rising sea levels. However, the impact of concomitant changes in atmospheric CO2 concentration, temperature, and vapor pressure deficit (VPD) on seawater-induced tree mortality is uncertain. We examined the mechanisms of seawater-induced mortality under varying climate scenarios using a photosynthetic gain and hydraulic cost optimization model validated against observations in a mature stand of Sitka spruce (Picea sitchensis) trees in the Pacific Northwest, USA, that were dying from recent seawater exposure. The simulations matched well with observations of photosynthesis, transpiration, nonstructural carbohydrates concentrations, leaf water potential, the percentage loss of xylem conductivity, and stand-level mortality rates. The simulations suggest that seawater-induced mortality could decrease by c. 16.7% with increasing atmospheric CO2 levels due to reduced risk of carbon starvation. Conversely, rising VPD could increase mortality by c. 5.6% because of increasing risk of hydraulic failure. Across all scenarios, seawater-induced mortality was driven by hydraulic failure in the first 2 yr after seawater exposure began, with carbon starvation becoming more important in subsequent years. Changing CO2 and climate appear unlikely to have a significant impact on coastal tree mortality under rising sea levels.

Risk factors for mental ill health in UK Army personnel: an overview.

Women in the UK military are more commonly diagnosed with a mental health disorder than men, but the reasons for this difference are not fully understood. This literature review identifies the risk factors for mental ill health in military personnel before serving, during service and as a veteran. The interaction of risk factors is complex and, in some cases, may be synergistic, such as experiencing adverse events in childhood and exposure to combat. Identification of risk factors allows further research to better understand differences between men and women, and the impact of these risk factors on army personnel. In turn this will inform better preventive strategies, which could be targeted at the primary, secondary or tertiary levels.

Postservice lower limb amputation in Scottish military veterans.

INTRODUCTION: Recent attention has focused on veterans who have lost limbs in conflict, but the number of UK veterans who lose limbs to disease is unknown. We used data from the Trends in Scottish Veterans' Health study to explore postservice lower limb amputation. METHODS: We carried out a retrospective cohort study of 78 000 veterans and 253 000 non-veterans born between 1945 and 1995, matched for age, sex and area of residence. We used survival analysis to examine the risk of amputation in veterans compared with non-veterans, and explored associations with antecedent disease. RESULTS: We found no difference between veterans and non-veterans in the risk of lower limb amputation, which was recorded in 145 (0.19%) veterans and 464 (0.18%) non-veterans (Cox proportional hazard ratio (HR) 1.00, 95% CIs 0.82 to 1.20, p=0.961). Peripheral arterial disease was recorded in two-thirds of both veteran and non-veteran amputees, and type 2 diabetes in 41% of veterans and 33% of non-veterans, with a dual diagnosis in 32% of veterans and 26% of non-veterans. Trauma was an infrequent cause of amputation. CONCLUSIONS: Although in later life veterans are no more likely to lose a limb to disease than non-veterans, the number so affected greatly outweighs those who have lost limbs in conflict. The high public profile of conflict-related limb loss risks eclipsing the needs of veterans with disease-related loss. Support for ageing veterans who have lost limbs due to disease will require planning with the same care as that afforded to the victims of conflict if inequalities are to be avoided.

Stability of tropical forest tree carbon-water relations in a rainfall exclusion treatment through shifts in effective water uptake depth.

Increasing severity and frequency of drought is predicted for large portions of the terrestrial biosphere, with major impacts already documented in wet tropical forests. Using a 4-year rainfall exclusion experiment in the Daintree Rainforest in northeast Australia, we examined canopy tree responses to reduced precipitation and soil water availability by quantifying seasonal changes in plant hydraulic and carbon traits for 11 tree species between control and drought treatments. Even with reduced soil volumetric water content in the upper 1 m of soil in the drought treatment, we found no significant difference between treatments for predawn and midday leaf water potential, photosynthesis, stomatal conductance, foliar stable carbon isotope composition, leaf mass per area, turgor loss point, xylem vessel anatomy, or leaf and stem nonstructural carbohydrates. While empirical measurements of aboveground traits revealed homeostatic maintenance of plant water status and traits in response to reduced soil moisture, modeled belowground dynamics revealed that trees in the drought treatment shifted the depth from which water was acquired to deeper soil layers. These findings reveal that belowground acclimation of tree water uptake depth may buffer tropical rainforests from more severe droughts that may arise in future with climate change.

General health status in young people with intellectual disabilities with and without Down syndrome in, and transitioning from, special education: findings from the National Longitudinal Transitions Study-2.

BACKGROUND: There has been little prior investigation of the general health of young people with intellectual disabilities across transition, nor separately for youth with intellectual disabilities with or without Down syndrome, despite general health being a strong predictor of subsequent health service use, hospital admissions and mortality in the general population. We aimed to investigate general health status in youth with intellectual disabilities with and without Down syndrome over the transitional period and quantify the extent to which personal characteristics, parental relationship and household income are associated with general health status. METHODS: The National Longitudinal Transitions Study-2 includes a nationally representative sample of youth receiving special education services aged 13-17 years at wave 1, followed up over 10 years in five waves of data collection. Data on general health status of youth with intellectual disabilities with and without Down syndrome were obtained from parent reports. We summarised overall demographics and general health status and plotted general health status for those who had health data available for all five waves. We then used random-effects ordered logistic regression to investigate whether wave of data collection, age, sex, Down syndrome, ethnicity, parental relationship status and household income are associated with general health status. RESULTS: At wave 1, data on intellectual disabilities were available on 9008/9576 (94.1%) young people, and 871/9008 (9.7%) of them had intellectual disabilities, of whom 125/871 (14.4%) had Down syndrome. Youth with intellectual disabilities with or without Down syndrome had low rates of excellent or very good health. Across waves 1-5, there was a shallow gradient in the proportion of youth with intellectual disabilities reporting excellent/very good health, from 57.7% at 13-17 years to 52.6% at 21-25 years, being more marked for those without Down syndrome (57.8% at 13-17 years to 51.8% at 21-25 years). However, contrary to our expectations, an ordinal measure of general health status did not decline over this transitional period and did not differ between youth with and without Down syndrome. There was a gradient with higher income associated with better health, significantly so over $50 001 (odds ratio = 0.559, 95% confidence interval 0.366-0.854). Poorer health was experienced by youth with Hispanic, Latino or Spanish ethnicity (odds ratio = 1.790, 95% confidence interval 1.051-3.048). Female sex and parental relationship status were not associated with health status. CONCLUSIONS: Young people with intellectual disabilities have bad health, and require support across all ages, including transition. Schools, teachers and staff in transitional services should consider health, and health care and support during transitional planning due to change in service provision and be aware of ethnicity and the stressful effects of low household income. This is important as interventions based on provision of greater support can prevent adverse consequences.

Improving systems of care during and after a pregnancy complicated by hyperglycaemia: A protocol for a complex health systems intervention.

BACKGROUND: Many women with hyperglycaemia in pregnancy do not receive care during and after pregnancy according to standards recommended in international guidelines. The burden of hyperglycaemia in pregnancy falls disproportionately upon Indigenous peoples worldwide, including Aboriginal and Torres Strait Islander women in Australia. The remote and regional Australian context poses additional barriers to delivering healthcare, including high staff turnover and a socially disadvantaged population with a high prevalence of diabetes. METHODS: A complex health systems intervention to improve care for women during and after a pregnancy complicated by hyperglycaemia will be implemented in remote and regional Australia (the Northern Territory and Far North Queensland). The Theoretical Domains Framework was used during formative work with stakeholders to identify intervention components: (1) increasing workforce capacity, skills and knowledge and improving health literacy of health professionals and women; (2) improving access to healthcare through culturally and clinically appropriate pathways; (3) improving information management and communication; (4) enhancing policies and guidelines; (5) embedding use of a clinical register as a quality improvement tool. The intervention will be evaluated utilising the RE-AIM framework at two timepoints: firstly, a qualitative interim evaluation involving interviews with stakeholders (health professionals, champions and project implementers); and subsequently a mixed-methods final evaluation of outcomes and processes: interviews with stakeholders; survey of health professionals; an audit of electronic health records and clinical register; and a review of operational documents. Outcome measures include changes between pre- and post-intervention in: proportion of high risk women receiving recommended glucose screening in early pregnancy; diabetes-related birth outcomes; proportion of women receiving recommended postpartum care including glucose testing; health practitioner confidence in providing care, knowledge and use of relevant guidelines and referral pathways, and perception of care coordination and communication systems; changes to health systems including referral pathways and clinical guidelines. DISCUSSION: This study will provide insights into the impact of health systems changes in improving care for women with hyperglycaemia during and after pregnancy in a challenging setting. It will also provide detailed information on process measures in the implementation of such health system changes.

Use of hydraulic traits for modeling genotype-specific acclimation in cotton under drought.

Understanding the genetic and physiological basis of abiotic stress tolerance under field conditions is key to varietal crop improvement in the face of climate variability. Here, we investigate dynamic physiological responses to water stress in silico and their relationships to genotypic variation in hydraulic traits of cotton (Gossypium hirsutum), an economically important species for renewable textile fiber production. In conjunction with an ecophysiological process-based model, heterogeneous data (plant hydraulic traits, spatially-distributed soil texture, soil water content and canopy temperature) were used to examine hydraulic characteristics of cotton, evaluate their consequences on whole plant performance under drought, and explore potential genotype × environment effects. Cotton was found to have R-shaped hydraulic vulnerability curves (VCs), which were consistent under drought stress initiated at flowering. Stem VCs, expressed as percent loss of conductivity, differed across genotypes, whereas root VCs did not. Simulation results demonstrated how plant physiological stress can depend on the interaction between soil properties and irrigation management, which in turn affect genotypic rankings of transpiration in a time-dependent manner. Our study shows how a process-based modeling framework can be used to link genotypic variation in hydraulic traits to differential acclimating behaviors under drought.

Environmental fluxes of perchlorate in rural catchments, Ontario, Canada.

Quantitative information about fluxes of perchlorate in the environment is lacking. This study reports analyses of perchlorate in various environmental waters sampled from rural headwater catchments in the Thames River basin in southern Ontario (Canada) that provide evidence about the fluxes and fate of perchlorate in the environment. Concentrations in streams (16 to 1047 ng/L) were used to estimate exports from these rural catchments (228-1843 mg/(ha·year)), atmospheric deposition (1480 ± 230 mg/(ha·year)), as well as variable rates of microbial degradation of perchlorate, which appeared to be enhanced in catchments with higher percentages of wetlands. Groundwater data supported earlier evidence that degradation of perchlorate occurs in the subsurface under oxygen-depleted conditions. The stream data suggest that the rate of degradation varies strongly between catchments and ranges up to >1000 mg/(ha·year).