The intraocular pressure response to dehydration : a pilot study

This study was designed to determine the Intraocular Pressure (IOP) response to differing levels of dehydration. Seven males participated in a 90 minute treadmill walk (5 km/h and 1 % grade) in both a cool (22 °C) and hot (43 °C) climate. At Baseline and at 30 minute intervals measurements of IOP, by tonometery, and indicators of hydration status (nude weight and plasma osmolality (Posm)) were taken. Body temperature and heart rate were also measured at these time points. Statistically significant interactions (time point (4) by trial (2)) were observed for IOP (F = 10.747, p = 0.009) and body weight loss (F = 50.083, p < 0.001) to decrease, and Posm (F = 34.867, p < 0.001) to increase, by a significantly greater amount during the hot trial compared to the cool. A univariate general linear model showed a significant relationship between IOP and body weight loss (F = 37.63, p < 0.001) and Posm (F = 38.53, p < 0.001). A significant interaction was observed for body temperature (F = 20.908, p < 0.001) and heart rate (F = 25.487, p < 0.001) between the trials and time points, but there was negligible association between these variables and IOP (Pearson correlation coefficient < ±0.5). The present study provides evidence to suggest that IOP is influenced by hydration status.

GABAergic modification of myopic and hyperopic ocular tissue effects on scleral fibroblast growth

Purpose: Myopia is a common eye disorder affecting up to 90% of children in South East Asia and 30% of the population worldwide. Myopia of high severity is a leading cause of blindness around the world (4th to 5th most common). Changes and remodelling of the sclera i.e. increase cellular proliferation & increase protein synthesis within scleral cells (↑ scleral DNA) and thinning and lose of extracellular matrix of sclera (↓ scleral GAG synthesis) have been linked to myopic eye growth in animal models. Signals acting on the sclera are thought to originate in the retina, and are modulated by the retinal pigment epithelium (RPE) with limited evidence suggesting that the RPE can modify scleral cell growth in culture. However, the mechanism of retinal signal transmission and the role of posterior eye cup tissue, including the RPE, in mediating changes in scleral fibroblast growth during myopia development are unclear. Retinal transmitter systems are critically involved in pathways regulating eye growth, which ultimately lead to alterations in the sclera if eye size is to change. A dopaminergic agonist and muscarinic antagonists decrease the proliferation of scleral chondrocytes when co-cultured with chick’s retinal pigment epithelium (RPE). GABA receptors have recently been localised to chick sclera. We therefore hypothesised that posterior eye cup tissue from myopic eyes would stimulate and from hyperopic eyes would inhibit growth of scleral fibroblasts in vitro and that GABAergic agents could directly interact with scleral cells or indirectly modify the effects of myopic and hyperopic posterior eye cup tissue on scleral fibroblast growth. Method: Fibroblastic cells obtained from 8-day-old chick sclera were used to establish cell banks. Two major experiments were performed. Experiment 1: To determine if posterior eye cup tissues from myopic eye stimulates and hyperopic eye inhibits scleral cell proliferation, when co-cultured with scleral cells in vitro. This study comprised two linked experiments, i) monocular visual treatments of FDM (form-deprivation myopia), LIM (lens-induced myopia) and LIH (lens-induced hyperopia) with assessment of the effect of full punch eye cup tissue on DNA and GAG synthesis by cultured chick scleral fibroblasts, and ii) binocular visual treatments comprising LIM and LIH with assessment of the effect of individual layers of eye cup tissues (neural retina, RPE and choroid) on cultured chick scleral fibroblasts. Visual treatment was applied for 3 days. Experiment 2: To determine the direct interaction of GABA agents on scleral cell growth and to establish whether GABA agents modify the stimulatory/inhibitory effect of myopic and hyperopic posterior eye cup tissues on cultured scleral cell growth in vitro. Two linked experiments were performed. i) GABA agonists (muscimol and baclofen) and GABA antagonists (bicuculine (-), CGP46381 and TPMPA) were added to scleral cell culture medium to determine their direct effect on scleral cells. ii) GABAergic agents (agonists and antagonists) were administered to scleral fibroblasts co-cultured with posterior eye cup tissue (retina, RPE, retina/RPE, RPE/choroid). Ocular tissues were obtained from chick eyes wearing +15D (LIH) or -15D lenses (LIM) for 3 days. In both experiments, tissues were added to hanging cell culture insert (pore size 1.0ìm) placed over each well of 24 well plates while scleral cells were cultured in DMEM/F12, Glutamax (Gibco) plus 10% FBS and penicillin/streptomycin (50U/ml)) and fungizone (1.25ug/ml) (Gibco), at seeding density of 30,000 cells/well at the bottom of the well and allowed to grow for 3 days. Scleral cells proliferation rate throughout the study was evaluated by determining GAG and DNA content of scleral cells using Dimethylmethylene blue (DMMB) dye and Quant-iTTm Pico Green® dsDNA reagent respectively. Results and analysis: Based on DNA and GAG content, there was no significant difference in tissue effect of LIM and LIH eyes on scleral fibroblast growth (DNA: 8.4 ± 1.1μg versus 9.3 ± 2.3 μg, p=0.23; GAG: 10.13 ± 1.4 μg versus 12.67 ± 1.2 μg, F2,23=6.16, p=0.0005) when tissues were obtained from monocularly treated chick eyes (FDM or +15D lens or -15D lens over right eyes with left eyes untreated) and co-cultured as full punch. When chick eyes were treated binocularly with -15D lens (LIM) right eye and +15D lens (LIH) left eyes and tissue layers were separated, the retina from LIM eyes did not stimulate scleral cell proliferation compared to LIH eyes (DNA: 27.2 ± 6.7 μg versus 23.2 ± 1.5 μg, p=0.23; GAG: 28.1 ±3.7 μg versus 28.7 ± 4.2 μg, p=0.21). Similarly, the LIH and LIM choroid did not produce a differential effect based on DNA (LIM 46.9 ± 6.4 μg versus LIH 53.5 ± 4.7 μg, p=0.18), however the choroid from LIH eyes induced higher scleral GAG content than from LIM eyes (32.5 ± 6.7 μg versus 18.9 ± 1.2 μg, p=0.023). In contrast, the RPE from LIM eyes caused a significant increase in fibroblast proliferation whereas the RPE from LIH eyes was relatively inhibitory (72.4 ± 6.3 μg versus 27.9 ± 2.3 μg, F1, 6=69.99, p=0.0005). GAG data were opposite to DNA data e.g. the RPE from LIH eyes increased (33.7 ± 7.9 μg) while the RPE from LIM eyes decreased (28.2 ± 3.0 μg) scleral cell growth (F1, 6=13.99, p=0.010). Based on DNA content, GABA agents had a small direct effect on scleral cell growth; GABA agonists increased (21.4 ± 1.0% and 18.3 ± 1.0% with muscimol and baclofen, p=0.0021), whereas GABA antagonists decreased fibroblast proliferation (-23.7 ± 0.9% with bicuculine & CGP46381 and -28.1 ± 0.5% with TPMPA, p=0.0004). GABA agents also modified the effect of LIM and LIH tissues (p=0.0005).The increase in proliferation rate of scleral fibroblasts co-cultured with tissues (RPE, retina, RPE/retina and RPE/choroid) from LIM treated eyes was enhanced by GABA agonists (muscimol: 27.4 ± 1.2%, 35.8 ± 1.6%, 8.4 ± 0.3% and 11.9 ± 0.6%; baclofen: 27.0 ± 1.0%, 15.8 ± 1.5%, 16.8 ± 1.2% and 15.4 ± 0.4%, p=0.014) whereas GABA antagonists further reduced scleral fibroblasts growth (bicuculine: -52.5 ± 2.5%, -36.9 ± 1.4%, -37.5 ± 0.6% and -53.7 ± 0.9%; TPMPA: 57.3 ± 1.3%, -15.7 ± 1.2%, -33.5 ± 0.4% and -45.9 ± 1.5%; CGP46381: -51.9 ± 1.6%, -28.5 ± 1.5%, -25.4 ± 2.0% and -45.5 ± 1.9% respectively, p=0.0034). GAG data were opposite to DNA data throughout the experiment e.g. GABA agonists further inhibited while antagonists relatively enhanced scleral fibroblasts growth for both LIM and LIH tissue co-culture. The effect of GABA agents was relatively lower (p=0.0004) for tissue from LIH versus LIM eyes but was in a similar direction. There was a significant drug effect on all four tissue types e.g. RPE, retina, RPE/retina and RPE/choroid for both LIM and LIH tissue co-culture (F20,92=3.928, p=0.0005). However, the effect of GABA agents was greatest in co-culture with RPE tissue (F18,36=4.865, p=0.0005). Summary and Conclusion: 1) Retinal defocus signals are transferred to RPE and choroid which then exert their modifying effect on scleral GAG and DNA synthesis either through growth stimulating factors or directly interacting with scleral cells in process of scleral remodeling during LIM and LIH visual conditions. 2) GABAergic agents affect the proliferation of scleral fibroblasts both directly and when co-cultured with ocular tissues in vitro.

Assessment of daily light and ultraviolet exposure in young adults

Purpose: There are some limited reports, based on questionnaire data, which suggest that outdoor activity decreases the risk of myopia in children and may offset the myopia risk associated with prolonged near work. The aim of this study was to explore the relationship between near work, indoor illumination, daily sunlight and ultraviolet (UV) exposure in emmetropic and myopic University students, given that University students perform significant amounts of near work and as a group have a high prevalence of myopia. Methods: Participants were 35 students, aged 17 to 25 years who were classified as being emmetropic (n=13), or having stable (n=12) or progressing myopia (n=10). During waking hours on three separate days participants wore a light sensor data logger (HOBO) and a polysulphone UV dosimeter; these devices measured daily illuminance and accumulative UV exposure respectively; participants also completed a daily activity log. Results: No significant between group differences were observed for average daily illuminance (p=0.732), number of hours per day spent in sunlight (p=0.266), outdoor shade (p=0.726), bright indoor/dim outdoor light (p=0.574) or dim room illumination (p=0.484). Daily UV exposure was significantly different across the groups (p=0.003); with stable myopes experiencing the greatest UV exposure (versus emmetropes p=0.002; versus progressing myopes p=0.004). Conclusions: The current literature suggests there is a link between myopia protection and spending time outdoors in children. Our data provides some evidence of this relationship in young adults and highlights the need for larger studies to further investigate this relationship longitudinally.

Vitamin D intake, sun exposure and 25-hydroxy vitamin D status in Peritoneal dialysis (PD) and Haemodialysis (HD) patients

Inadequate vitamin D levels have been linked to bone disease but more recently have been associated with wider health implications. Limited studies suggest a high prevalence of Vitamin D deficiency in dialysis patients, although evidence is lacking on whether this is due to dietary restrictions, limited mobility and time outdoors or a combination of these. The aim of this study was to assess the contributions of diet, supplements and sunlight exposure to serum Vitamin D (25(OH)D) levels in dialysis patients. Cross-sectional data were obtained from 30 PD (Mean±SD age 56.9±16.2 y; n=13 male) and 22 HD (Mean±SD age 65.4±14.0 y; n=18 male) patients between 2009 and 2010. Serum 25(OH)D was measured and oral vitamin D intake estimated through a food-frequency-questionnaire and quantifying inactive supplementation. Sunlight exposure was assessed using a validated questionnaire. Prevalence of inadequate/insufficient vitamin D differed between dialysis modality (31% and 43% insufficient (<50nmol/L); 4% and 34% deficient (<25nmol/L) in HD and PD patients respectively (p=0.002)). In HD patients, there was a significant correlation between diet plus supplemental vitamin D intake and 25(OH)D (ρ=0.84, p<0.001). Results suggest a higher frequency of 25(OH)D inadequacy/deficiency in PD compared to HD patients. No other relationships between intake, sun exposure and 25(OH)D were seen. This could reflect limitations of the study design or the importance of other factors such as age, ethnicity and sun protection as interactions in the analysis. Understanding these factors is important given Vitamin D’s emerging status as a biomarker of systemic ill health.

Fatalism, superstition, religion, and culture : road user beliefs and behaviour in Pakistan

Road traffic crashes have emerged as a major health problem around the world. Road crash fatalities and injuries have been reduced significantly in developed countries, but they are still an issue in low and middle-income countries. The World Health Organization (WHO, 2009) estimates that the death toll from road crashes in low- and middle-income nations is more than 1 million people per year, or about 90% of the global road toll, even though these countries only account for 48% of the world's vehicles. Furthermore, it is estimated that approximately 265,000 people die every year in road crashes in South Asian countries and Pakistan stands out with 41,494 approximately deaths per year. Pakistan has the highest rate of fatalities per 100,000 population in the region and its road crash fatality rate of 25.3 per 100,000 population is more than three times that of Australia's. High numbers of road crashes not only cause pain and suffering to the population at large, but are also a serious drain on the country's economy, which Pakistan can ill-afford. Most studies identify human factors as the main set of contributing factors to road crashes, well ahead of road environment and vehicle factors. In developing countries especially, attention and resources are required in order to improve things such as vehicle roadworthiness and poor road infrastructure. However, attention to human factors is also critical. Human factors which contribute to crashes include high risk behaviours like speeding and drink driving, and neglect of protective behaviours such as helmet wearing and seat belt wearing. Much research has been devoted to the attitudes, beliefs and perceptions which contribute to these behaviours and omissions, in order to develop interventions aimed at increasing safer road use behaviours and thereby reducing crashes. However, less progress has been made in addressing human factors contributing to crashes in developing countries as compared to the many improvements in road environments and vehicle standards, and this is especially true of fatalistic beliefs and behaviours. This is a significant omission, since in different cultures in developing countries there are strong worldviews in which predestination persists as a central idea, i.e. that one's life (and death) and other events have been mapped out and are predetermined. Fatalism refers to a particular way in which people regard the events that occur in their lives, usually expressed as a belief that an individual does not have personal control over circumstances and that their lives are determined through a divine or powerful external agency (Hazen & Ehiri, 2006). These views are at odds with the dominant themes of modern health promotion movements, and present significant challenges for health advocates who aim to avert road crashes and diminish their consequences. The limited literature on fatalism reveals that it is not a simple concept, with religion, culture, superstition, experience, education and degree of perceived control of one's life all being implicated in accounts of fatalism. One distinction in the literature that seems promising is the distinction between empirical and theological fatalism, although there are areas of uncertainty about how well-defined the distinction between these types of fatalism is. Research into road safety in Pakistan is scarce, as is the case for other South Asian countries. From the review of the literature conducted, it is clear that the descriptions given of the different belief systems in developing countries including Pakistan are not entirely helpful for health promotion purposes and that further research is warranted on the influence of fatalism, superstition and other related beliefs in road safety. Based on the information available, a conceptual framework is developed as a means of structuring and focusing the research and analysis. The framework is focused on the influence of fatalism, superstition, religion and culture on beliefs about crashes and road user behaviour. Accordingly, this research aims to provide an understanding of the operation of fatalism and related beliefs in Pakistan to assist in the development and implementation of effective and culturally appropriate interventions. The research examines the influence of fatalism, superstition, religious and cultural beliefs on risky road use in Pakistan and is guided by three research questions: 1. What are the perceptions of road crash causation in Pakistan, in particular the role of fatalism, superstition, religious and cultural beliefs? 2. How does fatalism, superstition, and religious and cultural beliefs influence road user behaviour in Pakistan? 3. Do fatalism, superstition, and religious and cultural beliefs work as obstacles to road safety interventions in Pakistan? To address these questions, a qualitative research methodology was developed. The research focused on gathering data through individual in-depth interviewing using a semi-structured interview format. A sample of 30 participants was interviewed in Pakistan in the cities of Lahore, Rawalpindi and Islamabad. The participants included policy makers (with responsibility for traffic law), experienced police officers, religious orators, professional drivers (truck, bus and taxi) and general drivers selected through a combination of purposive, criterion and snowball sampling. The transcripts were translated from Urdu and analysed using a thematic analysis approach guided by the conceptual framework. The findings were divided into four areas: attribution of crash causation to fatalism; attribution of road crashes to beliefs about superstition and malicious acts; beliefs about road crash causation linked to popular concepts of religion; and implications for behaviour, safety and enforcement. Fatalism was almost universally evident, and expressed in a number of ways. Fate was used to rationalise fatal crashes using the argument that the people killed were destined to die that day, one way or another. Related to this was the sense of either not being fully in control of the vehicle, or not needing to take safety precautions, because crashes were predestined anyway. A variety of superstitious-based crash attributions and coping methods to deal with road crashes were also found, such as belief in the role of the evil eye in contributing to road crashes and the use of black magic by rivals or enemies as a crash cause. There were also beliefs related to popular conceptions of religion, such as the role of crashes as a test of life or a source of martyrdom. However, superstitions did not appear to be an alternative to religious beliefs. Fate appeared as the 'default attribution' for a crash when all other explanations failed to account for the incident. This pervasive belief was utilised to justify risky road use behaviour and to resist messages about preventive measures. There was a strong religious underpinning to the statement of fatalistic beliefs (this reflects popular conceptions of Islam rather than scholarly interpretations), but also an overlap with superstitious and other culturally and religious-based beliefs which have longer-standing roots in Pakistani culture. A particular issue which is explored in more detail is the way in which these beliefs and their interpretation within Pakistani society contributed to poor police reporting of crashes. The pervasive nature of fatalistic beliefs in Pakistan affects road user behaviour by supporting continued risk taking behaviour on the road, and by interfering with public health messages about behaviours which would reduce the risk of traffic crashes. The widespread influence of these beliefs on the ways that people respond to traffic crashes and the death of family members contribute to low crash reporting rates and to a system which appears difficult to change. Fate also appeared to be a major contributing factor to non-reporting of road crashes. There also appeared to be a relationship between police enforcement and (lack of) awareness of road rules. It also appears likely that beliefs can influence police work, especially in the case of road crash investigation and the development of strategies. It is anticipated that the findings could be used as a blueprint for the design of interventions aimed at influencing broad-spectrum health attitudes and practices among the communities where fatalism is prevalent. The findings have also identified aspects of beliefs that have complex social implications when designing and piloting driver intervention strategies. By understanding attitudes and behaviours related to fatalism, superstition and other related concepts, it should be possible to improve the education of general road users, such that they are less likely to attribute road crashes to chance, fate, or superstition. This study also underscores the understanding of this issue in high echelons of society (e.g., policy makers, senior police officers) as their role is vital in dispelling road users' misconceptions about the risks of road crashes. The promotion of an evidence or scientifically-based approach to road user behaviour and road safety is recommended, along with improved professional education for police and policy makers.

The roles of procedural justice and social learning in improving self organizing capabilities of local communities for sustainable development in decentralized Indonesia

The development planning process under Law No. 25/2004 is said to be a new approach to increase public participation in decentralised Indonesia. This Law has introduced planning mechanisms, called Musyawarah Perencanaan Pembangunan (Musrenbang), to provide a forum for development planning. In spite of the expressed intention of these mechanisms to improve public participation, some empirical observations have cast doubt on the outcomes. As a result, some local governments have tried to provide alternative mechanisms to promote for participation in local development planning. Since planning is often said to be one of the most effective ways to improve community empowerment, it is of particular concern, to examine the extent to which the current local development planning processes in Indonesia provide sufficient opportunities to improve the self organising capabilities of communities to sustain development programs to meet local needs. With this objective in mind, this paper examines problems encountered by the new local planning mechanism (Musrenbang) in increasing local community empowerment particularly regarding their self organising capabilities. The concept of community empowerment as a pathway to social justice is explored to identify its key elements and approaches and to show how they can be incorporated within planning processes. Having discussed this, it is then argued that to change current unfavorable outcomes, procedural justice and social learning approaches need to be adopted as pathways to community empowerment. Lastly it is also suggested that an alternative local planning process, called Sistem Dukungan (SISDUK), introduced in South Suluwezi in collaboration with JAICA in 2006 (?) offers scope to incorporate such procedural justice and social learning approaches to improve the self organizing capabilities of local communities.

Language and utilisation of emergency care in Queensland

Objective: To compare access and utilisation of EDs in Queensland public hospitals between people who speak only English at home and those who speak another language at home. Methods: A retrospective analysis of a Queensland statewide hospital ED dataset (ED Information System) from 1 January 2008 to 31 December 2010 was conducted. Access to ED care was measured by the proportion of the state’s population attending EDs. Logistic regression analyses were performed to determine the relationships between ambulance use and language, and between hospital admission and language, both after adjusting for age, sex and triage category. Results: The ED utilisation rate was highest in English only speakers (290 per 1000 population), followed by Arabic speakers (105), and lowest among German speakers (30). Compared with English speakers, there were lower rates of ambulance use in Chinese (odds ratio 0.50, 95% confidence interval, 0.47–0.54), Vietnamese (0.87, 0.79–0.95), Arabic (0.87, 0.78–0.97), Spanish (0.56, 0.50–0.62), Italian (0.88, 0.80–0.96), Hindi (0.61, 0.53–0.70) and German (0.87, 0.79–0.90) speakers. Compared with English speakers, German speakers had higher admission rates (odds ratio 1.17, 95% confidence interval, 1.02–1.34), whereas there were lower admission rates in Chinese (0.90, 0.86–0.99), Arabic (0.76, 0.67–0.85) and Spanish (0.83, 0.75–0.93) speakers. Conclusion: This study showed that there was a significant association between lower utilisation of emergency care and speaking languages other than English at home. Further researches are needed using in-depth methodology to investigate if there are language barriers in accessing emergency care in Queensland.

Malnutrition and poor food intake are associated with prolonged hospital stay, frequent readmissions, and greater in-hospital mortality: Results from the Nutrition Care Day Survey 2010

Background & aims The Australasian Nutrition Care Day Survey (ANCDS) ascertained if malnutrition and poor food intake are independent risk factors for health-related outcomes in Australian and New Zealand hospital patients. Methods Phase 1 recorded nutritional status (Subjective Global Assessment) and 24-h food intake (0, 25, 50, 75, 100% intake). Outcomes data (Phase 2) were collected 90-days post-Phase 1 and included length of hospital stay (LOS), readmissions and in-hospital mortality. Results Of 3122 participants (47% females, 65 ± 18 years) from 56 hospitals, 32% were malnourished and 23% consumed ≤ 25% of the offered food. Malnourished patients had greater median LOS (15 days vs. 10 days, p < 0.0001) and readmissions rates (36% vs. 30%, p = 0.001). Median LOS for patients consuming ≤ 25% of the food was higher than those consuming ≤ 50% (13 vs. 11 days, p < 0.0001). The odds of 90-day in-hospital mortality were twice greater for malnourished patients (CI: 1.09–3.34, p = 0.023) and those consuming ≤ 25% of the offered food (CI: 1.13–3.51, p = 0.017), respectively. Conclusion The ANCDS establishes that malnutrition and poor food intake are independently associated with in-hospital mortality in the Australian and New Zealand acute care setting.

The impact of malnutrition and decreased food intake on length of stay, readmission, and mortality in acute care patients

Rationale: The Australasian Nutrition Care Day Survey (ANCDS) evaluated if malnutrition and decreased food intake are independent risk factors for negative outcomes in hospitalised patients. Methods: A multicentre (56 hospitals) cross-sectional survey was conducted in two phases. Phase 1 evaluated nutritional status (defined by Subjective Global Assessment) and 24-hour food intake recorded as 0, 25, 50, 75, and 100% intake. Phase 2 data, which included length of stay (LOS), readmissions and mortality, were collected 90 days post-Phase 1. Logistic regression was used to control for confounders: age, gender, disease type and severity (using Patient Clinical Complexity Level scores). Results: Of 3122 participants (53% males, mean age: 65±18 years) 32% were malnourished and 23% consumed�25% of the offered food. Median LOS for malnourished (MN) patients was higher than well-nourished (WN) patients (15 vs. 10 days, p<0.0001). Median LOS for patients consuming �25% of the food was higher than those consuming �50% (13 vs. 11 days, p<0.0001). MN patients had higher readmission rates (36% vs. 30%, p = 0.001). The odds ratios of 90-day in-hospital mortality were 1.8 times greater for MN patients (CI: 1.03 3.22, p = 0.04) and 2.7 times greater for those consuming �25% of the offered food (CI: 1.54 4.68, p = 0.001). Conclusion: The ANCDS demonstrates that malnutrition and/or decreased food intake are associated with longer LOS and readmissions. The survey also establishes that malnutrition and decreased food intake are independent risk factors for in-hospital mortality in acute care patients; and highlights the need for appropriate nutritional screening and support during hospitalisation. Disclosure of Interest: None Declared.

Temporal dynamics of rod and cone photoreceptor interactions under mesopic illumination

Purpose: Photoreceptor interactions reduce the temporal bandwidth of the visual system under mesopic illumination. The dynamics of these interactions are not clear. This study investigated cone-cone and rod-cone interactions when the rod (R) and three cone (L, M, S) photoreceptor classes contribute to vision via shared post-receptoral pathways. Methods: A four-primary photostimulator independently controlled photoreceptor activity in human observers. To determine the temporal dynamics of receptoral (L, S, R) and post-receptoral (LMS, LMSR, +L-M) pathways (5 Td, 7° eccentricity) in Experiment 1, ON-pathway sensitivity was assayed with an incremental probe (25ms) presented relative to onset of an incremental sawtooth conditioning pulse (1000ms). To define the post-receptoral pathways mediating the rod stimulus, Experiment 2 matched the color appearance of increased rod activation (30% contrast, 25-1000ms; constant cone excitation) with cone stimuli (variable L+M, L/L+M, S/L+M; constant rod excitation). Results: Cone-cone interactions with luminance stimuli (LMS, LMSR, L-cone) reduced Weber contrast sensitivity by 13% and the time course of adaptation was 23.7±1ms (μ±SE). With chromatic stimuli (+L-M, S), cone pathway sensitivity was also reduced and recovery was slower (+L-M 8%, 2.9±0.1ms; S 38%, 1.5±0.3ms). Threshold patterns at ON-conditioning pulse onset were monophasic for luminance and biphasic for chromatic stimuli. Rod-rod interactions increased sensitivity(19%) with a recovery time of 0.7±0.2ms. Compared to cone-cone interactions, rod-cone interactions with luminance stimuli reduced sensitivity to a lesser degree (5%) with faster recovery (42.9±0.7ms). Rod-cone interactions were absent with chromatic stimuli. Experiment 2 showed that rod activation generated luminance (L+M) signals at all durations, and chromatic signals (L/L+M, S/L+M) for durations >75ms. Conclusions: Temporal dynamics of cone-cone interactions are consistent with contrast sensitivity loss in the MC pathway for luminance stimuli and chromatically opponent responses in the PC and KC pathway with chromatic stimuli. Rod-cone interactions limit contrast sensitivity loss during dynamic illumination changes and increase the speed of mesopic light adaptation. The change in relative weighting of the temporal rod signal within the major post-receptoral pathways modifies the sensitivity and dynamics of photoreceptor interactions.

Effects of rice husk biochar and sugar-mill by-products on methane consumption from two different soils

Methane (CH4) is an important greenhouse gas with a global warming potential (GWP) 25 times greater than carbon dioxide (CO2) that can be produced or consumed in soils depending on environmental conditions and other factors. Biochar application to soils has been shown to reduce CH4 emissions and to increase CH4 consumption. However, the effects of rice husk biochar (RB) have not been thoroughly investigated. Two 60-day laboratory incubation experiments were conducted to investigate the effects of amending two soil types with RB, raw mill mud (MM) and composted mill mud (CM) on soil CH4 consumption and emissions. Soil cores incubated in 1 L glass jars and gas samples were analysed for CH4 using gas chromatography. Average CH4 consumption rates varied from -0.06 to -0.68 g CH4-C( )/ha/d in sandy loam soil and -0.59 to -1.00 g CH4-C/ha/d in clay soil. Application of RB resulted in CH4 uptake of -0.52 to -0.55 g CH4-C/ha/d in sandy loam and -0.76 to -0.91 g CH4-C/ha/d in clay soil. Addition of MM showed low CH4 emissions or consumption at 60% water-filled pore space (WFPS) in both soils. However, at high water contents (>75% WFPS) the application of MM produced high rates of CH4 emissions which were significantly suppressed when RB was added. Cumulative emissions of the MM treatment produced 108.9 g CH4-C/ha at 75% WFPS and 11 459.3 g CH4-C/ha at 90% WFPS in sandy loam soil over a period of 60 days. RB can increase CH4 uptake under low soil water content (SWC) and decrease CH4 emissions under anaerobic conditions. CM expressed more potential to reduce CH4 emissions than those of MM.

25 million years to break a continent : early to middle Miocene rifting and syn-extensional magmatism in the southern Gulf of California

Cenozoic extension in western Mexico has been divided into two episodes separated by the change from convergence to oblique divergence at the plate boundary. The Gulf Extensional Province is thought to have started once subduction ended at ~12.5 Ma whereas early extension is classified as Basin and Range. Mid-Miocene volcanism of the Comondú group has been considered as a subduction-related arc, whereas post ~12.5 Ma volcanism would be extension-related. Our new integration of the continental onshore and offshore geology of the south-east Gulf region, backed by tens of Ar-Ar and U-Pb ages and geochemical studies, document an early-mid Miocene rifting and extension-related bimodal to andesitic magmatism prior to subduction termination. Between ~21 and 11 Ma a system of NNW-SSE high-angle extensional faults rifted the western side of the Sierra Madre Occidental (SMO) ignimbrite plateau. In Nayarit, rhyolitic domes and some basalts were emplaced along this extensional belt at 18-17 Ma. These rocks show strong antecrystic inheritance but an absence of Mesozoic and older xenocrysts, suggesting a genesis in the mid-upper crust triggered by extension-induced basaltic influx. In Sinaloa, large grabens were floored by huge dome complexes at ~21-17 Ma and filled by continental sediments with interlayered basalts dated at 15 Ma. Mid-Miocene volcanism, including the largely volcaniclastic Comondú strata in Baja California, was thus emplaced in rift basins and appears associated to decompression melting rather than subduction. Along the coast, flat-lying basaltic lava flows dated at 11-10 Ma are exposed just above the present sea level. Here crustal thickness is 25-20 Km, almost half that in the core of the SMO, implying significant lithosphere stretching before ~11 Ma. This mafic pulse, with relatively high Ti but still clear Nb-Ta negative spikes, may be related to the detachment of the lower part of the subducted slab, allowing asthenosphere to flow into parts of the mantle previously fluxed by subduction fluids. Very uniform OIB-like lavas appear in late Pliocene and Pleistocene, only 18 m.y. after the onset of rifting and ~9 m.y. after the end of subduction. Our study shows that rifting began much earlier than Late Miocene and progressively overwhelmed subduction in generating magmatism.

Large igneous provinces and silicic large igneous provinces : progress in our understanding over the last 25 years

Large Igneous Provinces are exceptional intraplate igneous events throughout Earth’s history. Their significance and potential global impact is related to the total volume of magma intruded and released during these geologically brief events (peak eruptions are often within 1-5 Myrs duration) where millions to tens of millions of cubic kilometers of magma are produced. In some cases, at least 1% of the Earth’s surface has been directly covered in volcanic rock, being equivalent to the size of small continents with comparable crustal thicknesses. Large Igneous Provinces are thus important, albeit episodic episodes of new crust addition. However, most magmatism is basaltic so that contributions to crustal growth will not always be picked up in zircon geochronology studies that better trace major episodes of extension-related silicic magmatism and the silicic Large Igneous Provinces. Much headway has been made on our understanding of these anomalous igneous events over the last 25 years, driving many new ideas and models. This includes their: 1) global spatial and temporal distribution, with a long-term average of one event approximately every 20 Myrs, but a clear clustering of events at times of supercontinent break-up – Large Igneous Provinces are thus an integral part of the Wilson cycle and are becoming an increasingly important tool in reconnecting dispersed continental fragments; 2) compositional diversity that in part reflects their crustal setting of ocean basins, and continental interiors and margins where in the latter setting, LIP magmatism can be silicicdominant; 3) mineral and energy resources with major PGE and precious metal resources being hosted in these provinces, as well as magmatism impacting on the hydrocarbon potential of volcanic basins and rifted margins through enhancing source rock maturation, providing fluid migration pathways, and trap formation; 4) biospheric, hydrospheric and atmospheric impacts, with Large Igneous Provinces now widely regarded as a key trigger mechanism for mass extinctions, although the exact kill mechanism(s) are still being resolved; 5) role in mantle geodynamics and thermal evolution of the Earth, by potentially recording the transport of material from the lower mantle or core-mantle boundary to the Earth's surface and being a fundamental component in whole mantle convection models; and 6) recognition on the inner planets where the lack of plate tectonics and erosional processes and planetary antiquity means that the very earliest record of LIP events during planetary evolution may be better preserved than on Earth.

Sunlight and other determinants of circulating 25-hydroxyvitamin D levels in black and white participants in a nationwide U.S. study

Circulating 25-hydroxyvitamin D (25(OH)D), a marker for vitamin D status, is associated with bone health and possibly cancers and other diseases; yet, the determinants of 25(OH)D status, particularly ultraviolet radiation (UVR) exposure, are poorly understood. Determinants of 25(OH)D were analyzed in a subcohort of 1,500 participants of the US Radiologic Technologists (USRT) Study that included whites (n 842), blacks (n 646), and people of other races/ethnicities (n 12). Participants were recruited monthly (20082009) across age, sex, race, and ambient UVR level groups. Questionnaires addressing UVR and other exposures were generally completed within 9 days of blood collection. The relation between potential determinants and 25(OH)D levels was examined through regression analysis in a random two-thirds sample and validated in the remaining one third. In the regression model for the full study population, age, race, body mass index, some seasons, hours outdoors being physically active, and vitamin D supplement use were associated with 25(OH)D levels. In whites, generally, the same factors were explanatory. In blacks, only age and vitamin D supplement use predicted 25(OH)D concentrations. In the full population, determinants accounted for 25 of circulating 25(OH)D variability, with similar correlations for subgroups. Despite detailed data on UVR and other factors near the time of blood collection, the ability to explain 25(OH)D was modest.

The AusD Study: A population-based study of the determinants of serum 25-hydroxyvitamin D concentration across a broad latitude range

Observational studies suggest that people with a high serum 25-hydroxyvitamin D (25(OH)D) concentration may have reduced risk of chronic diseases such as osteoporosis, multiple sclerosis, type 1 diabetes, cardiovascular disease, and some cancers. The AusD Study (A Quantitative Assessment of Solar UV Exposure for Vitamin D Synthesis in Australian Adults) was conducted to clarify the relationships between ultraviolet (UV) radiation exposure, dietary intake of vitamin D, and serum 25(OH)D concentration among Australian adults residing in Townsville (19.3°S), Brisbane (27.5°S), Canberra (35.3°S), and Hobart (42.8°S). Participants aged 18-75 years were recruited from the Australian Electoral Roll between 2009 and 2010. Measurements were made of height, weight, waist:hip ratio, skin, hair, and eye color, blood pressure, and grip strength. Participants completed a questionnaire on sun exposure and vitamin D intake, together with 10 days of personal UV dosimetry and an associated sun-exposure and physical-activity diary that was temporally linked to a blood test for measurement of 25(OH)D concentration. Ambient solar UV radiation was also monitored at all study sites. We collected comprehensive, high-quality data from 1,002 participants (459 males, 543 females) assessed simultaneously across a range of latitudes and through all seasons. Here we describe the scientific and methodological issues considered in designing the AusD Study.