1,196 research outputs found
Effects of Ground Level Ozone on Vegetation
All the experiments conducted in this project use ozone exposures that either are already currently
occurring or are expected to occur over UK uplands this century, if predictions of increasing âbackgroundâ
ozone exposure are correct. Uplands are particularly vulnerable to such increases, because they are
windy and wet â conditions which favour ozone uptake by vegetation. Consequently, the observations on
ozone effects on upland plant species are likely to occur in the foreseeable future, if they are not already
happening.
The novel field ozone exposure system at Keenley Fell (Northumberland) has been operating since spring
2007. Seasonal average increases in ozone exposure at 10 m from the release point were very small in
2007, increasing to around 5 ppb above ambient in 2008 and 2009. The effects of the ozone treatments
on this conservation-managed grassland should be seen in the context of this very modest increase in
annual mean exposure.
Average deposition velocity for ozone at Keenley Fell was between 1 mm/s (night) and 5 mm/s (mid-day),
varying with weather conditions. These flux data will assist with the modelling of ozone deposition to
upland grasslands. Limited flux measurements for CO2 showed uptake during the day and release at
night, as expected, and will contribute to modelling interactions between ozone and carbon fluxes under
these conditions.
The ozone treatments at Keenley Fell had no effect on total above-ground production in any of the three
years. However, there was a cumulative decrease in forb biomass, with an associated change in forb
species composition, over the three years. This was accompanied by an increase in grass biomass. These
effects of ozone are antagonistic to the objectives of the conservation management at this site.
The biomass and flowering of a small number of individual forb species were significantly reduced by
ozone exposure at Keenley Fell. Importantly, these species included the hemi-parasite Rhinanthus minor
which is frequently used to enhance species diversity in this type of conservation management. Hence,
the observed effects of ozone on species composition may partly have been caused through its adverse
effects on Rhinanthus .
Data compiled from several experiments show adverse effects of ozone on semi-natural plant species at
concentrations as low as 30 ppb, with 12 of the species studied showing effects at concentrations below
50 ppbv. Effects on roots were greater than on shoots, with potentially significant implications for
overwintering, drought tolerance and carbon sequestration
Facilitating access to voluntary and community services for patients with psychosocial problems: a before-after evaluation
Background: Patients with psychosocial problems may benefit from a variety of community, educational, recreational and voluntary sector resources, but GPs often under-refer to these through lack of knowledge and time. This study evaluated the acceptability and effectiveness of graduate primary care mental health workers (GPCMHWs) facilitating access to voluntary and community sector services for patients with psychosocial problems. Methods: Patients with psychosocial problems from 13 general practices in London were referred to a GPCMHW Community Link scheme providing information and support to access voluntary and community resources. Patient satisfaction, mental health and social outcomes, and use of primary care resources, were evaluated. Results: 108 patients consented to take part in the study. At three-month follow-up, 63 (58%) had made contact with a community service identified as suitable for their needs. Most were satisfied with the help provided by the GPCMHW in identifying and supporting access to a suitable service. There was a reduction in the number of patients with a probable mental health problem on the GHQ-12 from 83% to 52% (difference 31% (95% CI, 17% â 44%). Social adjustment improved and frequencies of primary care consultations and of prescription of psychotropic medications were reduced. Conclusion: Graduates with limited training in mental health and no prior knowledge of local community resources can help patients with psychosocial problems access voluntary and community services, and patients value such a scheme. There was some evidence of effectiveness in reducing psychosocial and mental health problems
Nitrous acid and nitrite in the atmosphere
Nitrous acid is a minor trace gas, yet has an important influence on OH concentrations in the troposphere. Gas phase concentrations in both rural and urban air are larger than predicted from laboratory studies of homogeneous or heterogeneous chemistry. A better understanding of the mechanisms which produce nitrous acid in the atmosphere will lead to improved model of nitrogen oxide and OH chemistry, particularly in polluted air
Magnetohydrodynamic properties of incompressible Meissner fluids
We consider a superconducting material that exists in the liquid state, more
precisely, in which the Meissner-Ochsenfeld effect persists in the liquid
state. First, we investigate how the shape of such a hypothetical Meissner
liquid will adapt to accomodate for an applied external field. In particular,
we analyse the case of a droplet of Meissner fluid, and compute the elongation
of the droplet and its quadrupole frequency as a function of the applied field.
Next, the influence of an applied field on the flow of the liquid is studied
for the case of a surface wave. We derive the dispersion relation for surface
waves on an incompressible Meissner fluid. We discuss some candidate
realizations of the Meissner fluids and for the case of a superconducting
colloid discuss which regime of wave lengths would be most affected by the
Meissner effect.Comment: 12 pages, 3 figure
Status of Rockwell-ERC high efficiency solar cell programs
Programs aimed at developing large area, high efficiency GaAs heteroface cells for low concentration space applications and high concentration terrestrial applications as well as other programs aimed at developing high efficiency multicolor devices for use in similar applications are described. An additional program aimed at achieving improved power to weight ratio by parting thin film solar cells from their growth substrates prior to their incorporation into an array assembly is also described. There is potential for multiple reuse of the substrates which could lead to reduced costs for such devices. Highlights of these programs and their interrelated contributions toward the goals of reducing specific weight, volume and cost of photovoltaic space power systems are discussed. Overall goals are summarized and current programs and their funding sources are listed
Survey of Infections Transmissible Between Baboons and Humans, Cape Town, South Africa
Baboons on South Africaâs Cape Peninsula come in frequent contact with humans. To determine potential health risks for both species, we screened 27 baboons from 5 troops for 10 infections. Most (56%) baboons had antibodies reactive or cross-reactive to human viruses. Spatial overlap between these species poses low but potential health risks
Predicting treatment outcome in psychological treatment services by identifying latent profiles of patients
BACKGROUND: The outcomes of psychological therapies for anxiety and depression vary across individuals and symptom domains. Being able to predict treatment response from readily available patient data at presentation has potentially important benefits in aiding decisions about the most suitable interventions for a patient. This paper presents a method of identifying subgroups of patients using latent profile analysis, and comparing response to psychological treatments between these profiles. METHODS: All outpatients taken into treatment at two psychological treatment services in London, UK and who provided basic demographic information and standardized symptom measures were included in the analysis (n=16636). RESULTS: Latent Profile Analysis was performed on intake data to identify statistically different groups of patients, which were then examined in longitudinal analyses to determine their capacity to predict treatment outcomes. Comparison between profiles showed considerable variation in recovery (74-15%), deterioration rates (5-20%), and levels of attrition (17-40%). Further variation in outcomes was found within the profiles when different intensities of psychological intervention were delivered. LIMITATIONS: Latent profiles were identified using data from two services, so generalisability to other services should be considered. Routinely collected patient data was included, additional patient information may further enhance utility of the profiles. CONCLUSIONS: These results suggest that intake data can be used to reliably classify patients into profiles that are predictive of outcome to different intensities of psychological treatment in routine care. Algorithms based on these kinds of data could be used to optimize decision-making and aid the appropriate matching of patients to treatment
Model Checking Control Communication of a FACTS Device
This paper concerns the design and verification of a realtime communication protocol for sensor data collection and processing between an embedded computer and a DSP. In such systems, a certain amount of data loss without recovery may be tolerated. The key issue is to define and verify the correctness in the presence of these lost data frames under real-time constraints. This paper describes a temporal verification that if the end processes do not detect that too many frames are lost, defined by comparison of error counters against given threshold values, then there will be a bounded delay between transmission of data frames and reception of control frames. This verification and others presented herein were performed with the model checkers SPIN and RT-SPIN
Trends in depression & anxiety symptom severity among mental health service attendees during the COVID-19 pandemic
Background: General population surveys have shown that some groups, particularly young women, experienced increased distress during nationally mandated restrictions to control the spread of COVID-19. However, there has been limited research on such trends among people with pre-existing mental health conditions, leaving mental health services ill equipped to plan for current and future lockdowns. /
Methods: Mean weekly scores on the GAD-7 and PHQ-9 between 01/01/2020-22/06/2020 (n=9,538 individuals) for all patients of two psychological treatment services (Improving Access to Psychological Therapies) in London, were compared to mean weekly scores from the same time periods in 2017-2019 (n=37,849). The proportion of scores which were above the clinical thresholds for âcasenessâ each week were compared, and scores between groups based on gender, age group, and ethnicity, were also compared. /
Results: Confirmed community transmission in the UK (26/02/2020-03/03/2020) and the announcement of the national âlockdownâ (23/03/2020) were associated with significant increases in anxiety symptom scores. âLockdownâ was associated with a decrease in depression scores. These changes were not maintained during lockdown. Significant increases in depression and anxiety were observed at week 23, as restrictions were eased. /
Limitations: This was an exploratory analysis in two services only. Residual confounding and selection biases cannot be ruled out. /
Conclusions: Differences in the weekly average symptom scores were short-term; they did not continue throughout âlockdownâ as might have been expected, except among older people. Replication of this study in other settings and investigating the potential benefits of more regular reviews or more intensive treatments for at-risk groups, are warranted
Evaluation of the pathways of tropospheric nitrophenol formation using a multiphase model
International audiencePhenols are a major class of volatile organic compounds (VOC) whose reaction within, and partitioning between, the gas and liquid phases affects their lifetime within the atmosphere, the local oxidising capacity, and the extent of production of nitrophenols, which are toxic chemicals. In this work, a zero-dimension box model was constructed to quantify the relative nitration pathways, and partitioning into the liquid phase, of mono-aromatic compounds in order to help elucidate the formation pathways of 2- and 4-nitrophenol in the troposphere. The liquid phase contributed significantly to the production of nitrophenols for liquid water content (Lc) values exceeding 3Ă10-9, and for a range of assumed liquid droplet diameter, even though the resultant equilibrium partitioning to the liquid phase was much lower. For example, in a ''typical'' model scenario, with Lc=3Ă10-7, 58% of nitrophenol production occurred in the liquid phase but only 2% of nitrophenol remained there, i.e. a significant proportion of nitrophenol observed in the gas phase may actually be produced via the liquid phase. The importance of the liquid phase was enhanced at lower temperatures, by a factor ~1.5?2 at 278 K cf. 298 K. The model showed that nitrophenol production was particularly sensitive to the values of the rate coefficients for the liquid phase reactions between phenol and OH or NO3 reactions, but insensitive to the rate coefficient for the reaction between benzene and OH, thus identifying where further experimental data are required
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