Cirrus parameterisation and the role of ice nuclei.

A parametrization of cirrus clouds formed by homogeneous nucleation is improved so that it can be used more easily in general-circulation models (GCMs) and climate models. The improved parametrization is completely analytical and requires no fitting of parameters to models or measurements; it compares well with full microphysical model results even when monodisperse aerosol particles are used in the parametrization to determine cirrus ice-crystal number densities. However, the presence of ice nuclei in the atmosphere can modify the formation of cirrus clouds. If sufficient ice particles have been generated by heterogeneous nucleation, the saturation ratio of the air parcel will never reach that required for homogeneous nucleation. We calculate the critical number density of ice nuclei, above which homogeneous nucleation will be suppressed. The critical number density depends on the temperature, the updraught velocity, and the supersaturation at which ice nuclei activate. The theory points to key uncertainties in our observations of ice nuclei in the upper troposphere; for ice nuclei that activate at relatively low supersaturations, number density is more important than a precise knowledge of the activation supersaturation. Overall, the theory provides a general framework within which to interpret observations and the results of full microphysical cloud models. The theory can provide analytical test cases as benchmarks for the testing of models in development, and can be implemented itself into larger-scale atmospheric models, such as GCMs. Copyright © 2005 Royal Meteorological Societ

Volatile organic compound fluxes and concentrations in London (ClearfLo)

Volatile organic compounds (VOCs) from anthropogenic sources such as fuel combustion or evaporative emissions can directly and indirectly affect human health. Some VOCs, such as benzene and 1,3- butadiene are carcinogens. These and other VOCs contribute to the formation of ozone (O3) and aerosol particles, which have effects on human health and the radiative balance of the atmosphere. Although in the UK VOC emissions are subject to control under European Commission Directive 2008/50/EC and emission reducing echnologies have been implemented, urban air pollution remains a concern. Urban air quality is likely to remain a priority since currently >50% of the global population live in urban areas with trends in urbanization and population migration predicted to increase. The ClearfLo project is a large multi-institutional consortium funded by the UK Natural Environment Research Council (NERC) and provides integrated measurements of meteorology, gas phase and particulate composition of the atmosphere over London. Both long term and IOP measurements were made at street and elevated locations at a range of sites across London and its surroundings during 2011 and 2012. Mixing ratios of a selection of nine VOCs were measured using a high sensitivity proton transfer reaction-mass spectrometer (PTR-MS) at a ground level urban background (North Kensington) and kerbside (Marylebone Road) site during the winter IOP. VOC fluxes were measured by virtually disjunct eddy covariance (vDEC) at an elevated urban site (King’s College Strand) in Aug-Dec 2012. Our results for the first IOP showed that most of the selected compound concentrations depended on traffic emissions, although there was a marked difference between the urban ackground and kerbside sites. We identified some temperature effects on VOC concentrations. We also present the first analyses of VOC flux measurements over London. Preliminary analyses indicate most compounds associated with vehicle emissions closely followed diurnal traffic counts. Fluxes of isoprene and methanol appear to be controlled by light intensity and temperature, consistent with a redominantly biogenic source of these compounds

Seasonal trends in concentrations and fluxes of volatile organic compounds above central London

Concentrations and fluxes of seven volatile organic compounds (VOCs) were measured between August and December 2012 at a roof-top site in central London as part of the ClearfLo project (Clean Air for London). VOC concentrations were quantified using a proton transfer reaction-mass spectrometer and fluxes were calculated using a virtual disjunct eddy covariance technique. The median VOC fluxes, including aromatics, oxygenated compounds and isoprene, ranged from 0.07 to 0.33 mg m−2 h−1 and mixing ratios were 7.27 ppb for methanol (m / z 33) and <1 ppb for the remaining compounds. Strong relationships were observed between most VOC fluxes and concentrations with traffic density, but also with photosynthetically active radiation (PAR) and temperature for the oxygenated compounds and isoprene. An estimated 50–90 % of aromatic fluxes were attributable to traffic activity, which showed little seasonal variation, suggesting boundary layer effects or possibly advected pollution may be the primary causes of increased concentrations of aromatics in winter. PAR and temperature-dependent processes accounted for the majority of isoprene, methanol and acetaldehyde fluxes and concentrations in August and September, when fluxes and concentrations were largest. Modelled biogenic isoprene fluxes using the G95 algorithm agreed well with measured fluxes in August and September, due to urban vegetation. Comparisons of estimated annual benzene emissions from the London and National Atmospheric Emissions Inventory agreed well with measured benzene fluxes. Flux footprint analysis indicated emission sources were localized and that boundary layer dynamics and source strengths were responsible for temporal and spatial VOC flux and concentration variability during the measurement period

Health human resources planning and the production of health: Development of an extended analytical framework for needs-based health human resources planning.

Traditional approaches to health human resources planning emphasize the role of demographic change on the needs for health human resources. Conceptual frameworks have been presented that recognize the limited role of demographic change and the broader determinants of health human resource requirements. Nevertheless, practical applications of health human resources planning continue to base plans on the size and demographic mix of the population applied to simple population-provider or population-utilization ratios. In this paper an analytical framework is developed based on the production of health care services and the multiple determinants of health human resource requirements. In this framework attention is focused on estimating the ‘flow’ of services required to meet the needs of the population that is then translated into the required ‘stock’ of providers to deliver this ‘flow’ of services. The requirements for human resources in the future is shown to depend on four elements: the size and demographic mix of the population (demography), the levels of risks to health and morbidity in the population (epidemiology), the services deemed appropriate to address the levels of risks to health and morbidity (standards of care), and the rate of service delivery by providers (productivity). Application of the framework is illustrated using hypothetical scenarios.health human resources planning, demography, epidemiology, standards of care, productivity

Human monocyte heat shock protein 72 responses to acute hypoxic exercise after 3 days of exercise heat acclimation

The aim of this study was to determine whether short-term heat acclimation (STHA) could confer increased cellular tolerance to acute hypoxic exercise in humans as determined via monocyte HSP72 (mHSP72) expression. Sixteen males were separated into two matched groups. The STHA group completed 3 days of exercise heat acclimation; 60 minutes cycling at 50% V˙O2peak in 40°C 20% relative humidity (RH). The control group (CON) completed 3 days of exercise training in 20°C, 40% RH. Each group completed a hypoxic stress test (HST) one week before and 48 hours following the final day of CON or STHA. Percentage changes in HSP72 concentrations were similar between STHA and CON following HST1 (P=0.97). STHA induced an increase in basal HSP72 (P=0.03) with no change observed in CON (P=0.218). Basal mHSP72 remained elevated before HST2 for the STHA group (P0.05). Percent change in mHSP72 was lower after HST2 in STHA compared to CON (P=0.02). The mHSP72 response to hypoxic exercise was attenuated following 3 days of heat acclimation. This is indicative of improved tolerance and ability to cope with the hypoxic insult, potentially mediated in part by increased basal reserves of HSP72

The impact of submaximal exercise during heat and/or hypoxia on the cardiovascular and monocyte HSP72 responses to subsequent (post 24 h) exercise in hypoxia

Background: The aims of this study were to describe the cellular stress response to prolonged endurance exercise in acute heat, hypoxia and the combination of heat and hypoxia and to determine whether prior acute exposure to these stressors improved cellular tolerance to a subsequent exercise bout in hypoxia 24 h later. Methods: Twelve males (age 22 ± 4 years, height 1.77 ± 0.05 m, mass 79 ± 12.9 kg, VO2 max 3.57 ± 0.7 L · min-1) completed four trials (30-min rest, 90-min cycling at 50% normoxic VO2 max) in normothermic normoxia (NORM; 18°C, FIO2 = 0.21), heat (HEAT; 40°C, 20% RH), hypoxia (HYP; FIO2 = 0.14) or a combination of heat and hypoxia (COM; 40°C, 20% RH, FIO2 = 0.14) separated by at least 7 days. Twenty-four hours after each trial, participants completed a hypoxic stress test (HST; 15-min rest, 60-min cycling at 50% normoxic VO2 max, FIO2 = 0.14). Monocyte heat shock protein 72 (mHSP72) was assessed immediately before and after each exercise bout. Results: mHSP72 increased post exercise in NORM (107% ± 5.5%, p &gt; 0.05), HYP (126% ± 16%, p

Law enforcement personnel are willing to change, but report influencing beliefs and barriers to optimised dietary intake

BACMROUND: Law enforcement personnel have been recognized as having a high risk for several lifestyle-related health conditions which, in combination with the nature of their work (sedentary roles interspersed with intermittent high-intensity activity, shift work, and a high stress-load), can have a negative impact on their health. The aim of this study was to investigate the dietary habits and factors or barriers influencing these habits within a cohort of law enforcement personnel in the United States of America. METHOD: Cross-sectional data were obtained via validated paper-based surveys being the Perceived Barriers to Healthy Eating, Food Choice Questionnaire and Rapid Eating Assessment for Participants, Short Version. RESULTS: A total of 159 participants (median age = 27 [range 19-60] years; 74% males) participated. Barriers to healthy eating included being busy and irregular working hours. Overall, 91% (n = 143) placed high importance on consuming nutritious food and 80% (n = 126) on food high in vitamins and minerals. A further 80% (n = 127) emphasized high protein content and 41% (n = 62) followed a high protein diet. Barriers to healthy eating included busy lifestyle (60%, n = 94), and irregular working hours (41%, n = 64). Overall, 80% (n = 127) were very willing to make changes in eating habits to be healthier. CONCLUSION: Law enforcement officers know what they should eat and report convenience and health the most important factors guiding their food choices. Knowing this, officers find challenges putting good dietary practices into practice due to factors like a busy lifestyle and irregular work hours. Reportedly "very willing" to make changes in their eating habits to be healthier, future interventions should focus on how to effect changes to their eating habits as opposed to focussing on what to eat.Full Tex

‘Quiet’ green community innovations at the interface of public and private ownership in an old neighbourhood in Zhengzhou, China

This paper examines informal urban gardening practices within a 70-year-old industrial neighbourhood in Zhengzhou, central China, employing the conceptual framework of ‘annexed common space for private green infrastructure’ (ACS-PGI). Through urban morphological and typological analysis, it interrogates how historical institutional legacies, urban land tenure regimes, local governance structures, socio-spatial configurations and cultural-agricultural traditions collectively inform and sustain these grassroots greening practices. Adopting a structural attribution system framework, the study advances a comprehensive understanding of the multifaceted structural determinants underpinning informal gardening. Departing from Western-centric interpretations that often frame such practices as acts of political contestation, the Zhengzhou case elucidates a historically embedded, socially legitimised and spatially articulated phenomenon rooted in collective memory, communal land-use rights and tacit state tolerance. This research contributes to urban socio-environmental scholarship by underscoring the necessity of situating informal urban greening within its distinct institutional and cultural-historical context, thereby offering critical insights for the theorisation of sustainable urban green infrastructure and community agency.</p

Neighbourhood-Scale Flow Regimes and Pollution Transport in Cities

Cities intimately intermingle people and air pollution. It is very difficult to monitor or model neighbourhood-scale pollutant transport explicitly. One computationally efficient way is to treat neighbourhoods as patches of porous media to which the flow adjusts. Here we use conceptual arguments and large-eddy simulation to formulate two flow regimes based on the size of patches of different frontal-area density within neighbourhoods. One of these flow regimes distributes pollutants in counter-intuitive ways, such as producing pollution ‘hot spots’ in patches of lower frontal-area density. The regimes provide the first quantitative definition of the ‘urban background’, which can be used for more precisely targeted pollution monitoring. They also provide a conceptual basis for further research into neighbourhood-scale air-pollution problems, such as parametrizations in mesoscale models, and the transport of fluid constituents in other porous media