398 research outputs found

    Slow releasing artificial tears for contact lens wearers with dry eyes

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    Thirteen contact lens patients with an objective and/or subjective diagnosis of dry eye were given a non-medicated (hydroxypropyl cellulose) slow releasing artificial tear (SR-AT). After two weeks of daily use, a majority of the patients reported positive results, including two patients with giant papillary conjunctivitis (GPC) and one with nocturnal lagophthalmos. It appears that this ocular insert may be beneficial for diagnosing the dry eye problems of contact lens wearers as well as non-contact lens wearers that are due to insufficient hydration and lubrication at the conjunctival/corneal and contact lens interface

    Quantifying responses of dung beetles to fire disturbance in tropical forests:the importance of trapping method and seasonality

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    Understanding how biodiversity responds to environmental changes is essential to provide the evidence-base that underpins conservation initiatives. The present study provides a standardized comparison between unbaited flight intercept traps (FIT) and baited pitfall traps (BPT) for sampling dung beetles. We examine the effectiveness of the two to assess fire disturbance effects and how trap performance is affected by seasonality. The study was carried out in a transitional forest between Cerrado (Brazilian Savanna) and Amazon Forest. Dung beetles were collected during one wet and one dry sampling season. The two methods sampled different portions of the local beetle assemblage. Both FIT and BPT were sensitive to fire disturbance during the wet season, but only BPT detected community differences during the dry season. Both traps showed similar correlation with environmental factors. Our results indicate that seasonality had a stronger effect than trap type, with BPT more effective and robust under low population numbers, and FIT more sensitive to fine scale heterogeneity patterns. This study shows the strengths and weaknesses of two commonly used methodologies for sampling dung beetles in tropical forests, as well as highlighting the importance of seasonality in shaping the results obtained by both sampling strategies

    Forest and Peatland Fire Dynamics in South Sumatra Province

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    South Sumatra Province experiences forest and land fires every year. Peatland and human activity have caused this region to be more vulnerable to fire. In this study, we used annual mapping to describe the history of forest and land fires in Ogan Komering Ilir (OKI) District of South Sumatra to analyze fire trends during the 2015-2019 period. Hotspot data were obtained from Terra/Aqua MODIS satellite imagery at all confidence levels. Burned areas were identified using the Normalized Burn Ratio (NBR) Index, with data sources from Landsat 8 satellite imagery obtained from the USGS (United States Geological Survey). The highest number of hotspots were detected in 2015 (33,748), with 72% was located on peatland. Historical analysis of hotspot numbers, shows that the majority of burning occurs in September and October. This indicates that prevention activities must be carried out more intensively before these months. Linear regression between annual hotspot numbers and rainfall was not significant. Hotspots indicative of forest and land fire in OKI District were more influenced by human activities. The largest burned area (993,999 ha) occurred in 2015. The 2015 El Niño event triggered drought and worsened forest and land fires in Indonesia. Although no El- Niño conditions occurred in 2016-2018, fires continued to occur in OKI District, showing their independence from extreme drought. The fires occurring on peatlands burned a large area during 2015-2019 indicating that forest and land fires management must become a top priority in OKI Distric

    Forest fire management, climate change, and the risk of catastrophic carbon losses

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    Approaches to management of fireprone forests are undergoing rapid change, driven by recognition that technological attempts to subdue fire at large scales (fire suppression) are ecologically and economically unsustainable. However, our current framework for intervention excludes the full scope of the fire management problem within the broader context of fire−vegetation−climate interactions. Climate change may already be causing unprecedented fire activity, and even if current fires are within the historical range of variability, models predict that current fire management problems will be compounded by more frequent extreme fire-conducive weather conditions (eg Fried et al. 2004)

    Field measurements of trace gases and aerosols emitted by peat fires in Central Kalimantan, Indonesia, during the 2015 El Niño

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    Peat fires in Southeast Asia have become a major annual source of trace gases and particles to the regional-global atmosphere. The assessment of their influence on atmospheric chemistry, climate, air quality, and health has been uncertain partly due to a lack of field measurements of the smoke characteristics. During the strong 2015 El Niño event we deployed a mobile smoke sampling team in the Indonesian province of Central Kalimantan on the island of Borneo and made the first, or rare, field measurements of trace gases, aerosol optical properties, and aerosol mass emissions for authentic peat fires burning at various depths in different peat types. This paper reports the trace gas and aerosol measurements obtained by Fourier transform infrared spectroscopy, whole air sampling, photoacoustic extinctiometers (405 and 870 nm), and a small subset of the data from analyses of particulate filters. The trace gas measurements provide emission factors (EFs; grams of a compound per kilogram biomass burned) for up to ∼ 90 gases, including CO2, CO, CH4, non-methane hydrocarbons up to C10, 15 oxygenated organic compounds, NH3, HCN, NOx, OCS, HCl, etc. The modified combustion efficiency (MCE) of the smoke sources ranged from 0.693 to 0.835 with an average of 0.772 ± 0.053 (n = 35), indicating essentially pure smoldering combustion, and the emissions were not initially strongly lofted. The major trace gas emissions by mass (EF as g kg-1) were carbon dioxide (1564 ± 77), carbon monoxide (291 ± 49), methane (9.51 ± 4.74), hydrogen cyanide (5.75 ± 1.60), acetic acid (3.89 ± 1.65), ammonia (2.86 ± 1.00), methanol (2.14 ± 1.22), ethane (1.52 ± 0.66), dihydrogen (1.22 ± 1.01), propylene (1.07 ± 0.53), propane (0.989 ± 0.644), ethylene (0.961 ± 0.528), benzene (0.954 ± 0.394), formaldehyde (0.867 ± 0.479), hydroxyacetone (0.860 ± 0.433), furan (0.772 ± 0.035), acetaldehyde (0.697 ± 0.460), and acetone (0.691 ± 0.356). These field data support significant revision of the EFs for CO2 (g-8 %), CH4 (g-55 %), NH3 (g-86 %), CO (+39 %), and other gases compared with widely used recommendations for tropical peat fires based on a lab study of a single sample published in 2003. BTEX compounds (benzene, toluene, ethylbenzene, xylenes) are important air toxics and aerosol precursors and were emitted in total at 1.5 ± 0.6 g kg-1. Formaldehyde is probably the air toxic gas most likely to cause local exposures that exceed recommended levels. The field results from Kalimantan were in reasonable agreement with recent lab measurements of smoldering Kalimantan peat for overlap species, lending importance to the lab finding that burning peat produces large emissions of acetamide, acrolein, methylglyoxal, etc., which were not measurable in the field with the deployed equipment and implying value in continued similar efforts. The aerosol optical data measured include EFs for the scattering and absorption coefficients (EF Bscat and EF Babs, m2 kg-1 fuel burned) and the single scattering albedo (SSA) at 870 and 405 nm, as well as the absorption Ångström exponents (AAE). By coupling the absorption and co-located trace gas and filter data we estimated black carbon (BC) EFs (g kg-1) and the mass absorption coefficient (MAC, m2 g-1) for the bulk organic carbon (OC) due to brown carbon (BrC). Consistent with the minimal flaming, the emissions of BC were negligible (0.0055 ± 0.0016 g kg-1). Aerosol absorption at 405 nm was ∼ 52 times larger than at 870 nm and BrC contributed ∼ 96 % of the absorption at 405 nm. Average AAE was 4.97 ± 0.65 (range, 4.29-6.23). The average SSA at 405 nm (0.974 ± 0.016) was marginally lower than the average SSA at 870 nm (0.998 ± 0.001). These data facilitate modeling climate-relevant aerosol optical properties across much of the UV/visible spectrum and the high AAE and lower SSA at 405 nm demonstrate the dominance of absorption by the organic aerosol. Comparing the Babs at 405 nm to the simultaneously measured OC mass on filters suggests a low MAC (∼ 0.1) for the bulk OC, as expected for the low BC/OC ratio in the aerosol. The importance of pyrolysis (at lower MCE), as opposed to glowing (at higher MCE), in producing BrC is seen in the increase of AAE with lower MCE (r2 = 0.65)

    O FUTURO DA AMAZÔNIA: MODELOS PARA PREVER AS CONSEQÜÊNCIAS DA INFRAESTRUTURA FUTURA NOS PLANOS PLURIANUAIS

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    Desde 1996 o planejamento de investimentos do governo brasileiro tem sido organizado em planos quadrianuais: Brasil em Ação (1996-1999), Avança Brasil (2000-2003), PPA [Plano Plurianual] (2004-2007), PAC [Programa de Aceleração do Crescimento] (2008-2011), e PAC-2 (2012-2015). Cada plano tem incluído uma longa lista de rodovias, barragens e outros grandes projetos de infraestrutura na Amazônia. Vários desses projetos têm sido incluídos em uma série de planos, pois restrições econômicas não permitiram a realização das obras no ritmo inicialmente imaginado. Este é o caso de obras como a hidrelétrica de Belo Monte e as rodovias BR-163 (Santarém-Cuiabá) e BR-319 (Manaus-Porto Velho). Estes projetos adiados estão hoje sendorealizados ou próximos à realização. Uma série de modelos tem sido elaborada por diferentes grupos para prever as consequências futuras, caso essas obras sejam realizadas. Diferentes modelos captam diferentes aspectos da problemática, e vários deles indicam grandes aumentos de desmatamento e degradação, com graves implicações ambientais e sociais. Um dos modelos parte da premissa de que as estradas teriam efeitos nulos ou até benéficos sobre total de desmatamento, mas essa suposição contradiz o que é observado no mundo real

    Association of Accelerometry-Measured Physical Activity and Cardiovascular Events in Mobility-Limited Older Adults: The LIFE (Lifestyle Interventions and Independence for Elders) Study.

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    BACKGROUND:Data are sparse regarding the value of physical activity (PA) surveillance among older adults-particularly among those with mobility limitations. The objective of this study was to examine longitudinal associations between objectively measured daily PA and the incidence of cardiovascular events among older adults in the LIFE (Lifestyle Interventions and Independence for Elders) study. METHODS AND RESULTS:Cardiovascular events were adjudicated based on medical records review, and cardiovascular risk factors were controlled for in the analysis. Home-based activity data were collected by hip-worn accelerometers at baseline and at 6, 12, and 24 months postrandomization to either a physical activity or health education intervention. LIFE study participants (n=1590; age 78.9±5.2 [SD] years; 67.2% women) at baseline had an 11% lower incidence of experiencing a subsequent cardiovascular event per 500 steps taken per day based on activity data (hazard ratio, 0.89; 95% confidence interval, 0.84-0.96; P=0.001). At baseline, every 30 minutes spent performing activities ≥500 counts per minute (hazard ratio, 0.75; confidence interval, 0.65-0.89 [P=0.001]) were also associated with a lower incidence of cardiovascular events. Throughout follow-up (6, 12, and 24 months), both the number of steps per day (per 500 steps; hazard ratio, 0.90, confidence interval, 0.85-0.96 [P=0.001]) and duration of activity ≥500 counts per minute (per 30 minutes; hazard ratio, 0.76; confidence interval, 0.63-0.90 [P=0.002]) were significantly associated with lower cardiovascular event rates. CONCLUSIONS:Objective measurements of physical activity via accelerometry were associated with cardiovascular events among older adults with limited mobility (summary score >10 on the Short Physical Performance Battery) both using baseline and longitudinal data. CLINICAL TRIAL REGISTRATION:URL: http://www.clinicaltrials.gov. Unique identifier: NCT01072500
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