Relationships of Photosynthetic Photon Flux Density, air Temperature and Humidity with Tomato Leaf Diffusive Conductance and Temperature

The objective was to study the leaf temperature (LT) and leaf diffusive vapor conductance (gs) responses to temperature, humidity and incident flux density of photosynthetically active photons (PPFD) of tomato plants grown without water restriction in a plastic greenhouse in Santa Maria, RS, Brazil. The plants were grown in substrate and irrigated daily. The gs was measured using a steady-state null-balance porometer on the abaxial face of the leaves during the daytime. Both leaf surfaces were measured in one day. The PPFD and LT were measured using the porometer. Leaf temperature was determined using an infrared thermometer, and air temperature and humidity were measured using a thermohygrograph. The leaves on the upper layer of the plants had higher gs than the lower layer. The relationship between the gs and PPFD was different for the two layers in the plants. A consistent relationship between the gs and atmospheric water demand was observed only in the lower layer. The LT tended to be lower than the air temperature. The mean value for the gs was 2.88 times higher on the abaxial than adaxial leaf surface.

Relationships of photosynthetic photon flux density, air temperature and humidity with tomato leaf diffusive conductance and temperature

The objective was to study the leaf temperature (LT) and leaf diffusive vapor conductance (gs) responses to temperature, humidity and incident flux density of photosynthetically active photons (PPFD) of tomato plants grown without water restriction in a plastic greenhouse in Santa Maria, RS, Brazil. The plants were grown in substrate and irrigated daily. The gs was measured using a steady-state null-balance porometer on the abaxial face of the leaves during the daytime. Both leaf surfaces were measured in one day. The PPFD and LT were measured using the porometer. Leaf temperature was determined using an infrared thermometer, and air temperature and humidity were measured using a thermohygrograph. The leaves on the upper layer of the plants had higher gs than the lower layer. The relationship between the gs and PPFD was different for the two layers in the plants. A consistent relationship between the gs and atmospheric water demand was observed only in the lower layer. The LT tended to be lower than the air temperature. The mean value for the gs was 2.88 times higher on the abaxial than adaxial leaf surface.

Effects of irrigation on water use and water use efficiency in two fast growing Eucalyptus plantations

Eucalyptus plantations occupy almost 20 million ha worldwide and exceed 3.7 million ha in Brazil alone. Improved genetics and silviculture have led to as much as a three-fold increase in productivity in Eucalyptus plantations in Brazil and the large land area occupied by these highly productive ecosystems raises concern over their effect on local water supplies. As part of the Brazil Potential Productivity Project, we measured water use of Eucalyptus grandis x urophylla clones in rainfed and irrigated stands in two plantations differing in productivity. The Aracruz (lower productivity) site is located in the state of Espirito Santo and the Veracel (higher productivity) site in Bahia state. At each plantation, we measured stand water use using homemade sap flow sensors and a calibration curve using the clones and probes we utilized in the study. We also quantified changes in growth, leaf area and water use efficiency (the amount of wood produced per unit of water transpired). Measurements were conducted for 1 year during 2005 at Aracruz and from August through December 2005 at Veracel. Transpiration at both sites was high compared to other studies but annual estimates at Aracruz for the rainfed treatment compared well with a process model calibrated for the Aracruz site (within 10%). Annual water use at Aracruz was 1394 mm in rainfed treatments versus 1779 mm in irrigated treatments and accounted for approximately 67% and 58% of annual precipitation and irrigation inputs respectively. Increased water use in the irrigated stands at Aracruz was associated with higher sapwood area, leaf area index and transpiration per unit leaf area but there was no difference in the response of canopy conductance with air saturation deficit between treatments. Water use efficiency at the Aracruz site was also not influenced by irrigation and was similar to the rainfed treatment. During the period of overlapping measurements, the response to irrigation treatments at the more productive Veracel site was similar to Aracruz. Stand water use at the Veracel site totaled 975 mm and 1102 mm in rainfed and irrigated treatments during the 5-month measurement period respectively. Irrigated stands at Veracel also had higher leaf area with no difference in the response of canopy conductance with air saturation deficit between treatments. Water use efficiency was also unaffected by irrigation at Veracel. Results from this and other studies suggest that improved resource availability does not negatively impact water use efficiency but increased productivity of these plantations is associated with higher water use and should be given consideration during plantation management decision making processes aimed at increasing productivity. Published by Elsevier B.V.

Color-space distortions following long-term occupational exposure to mercury vapor

Color vision was examined in subjects with long-term occupational exposure to mercury (Hg) vapor. The color vision impairment was assessed by employing a quantitative measure of distortion of individual and group perceptual color spaces. Hg subjects (n = 18; 42.1 +/- 6.5 years old; exposure time = 10.4 +/- 5.0 years; time away from the exposure source = 6.8 +/- 4.6 years) and controls (n = 18; 46.1 +/- 8.4 years old) were examined using two arrangement tests, D-15 and D-15d, in the traditional way, and also in a triadic procedure. From each subject`s `odd-one-out` choices, matrices of inter-cap subjective dissimilarities were derived and processed by non-metric multidimensional scaling (MDS). D-15d results differed significantly between the Hg-group and the control group (p < 0.05), with the impairment predominantly along the tritan axis. 2D perceptual color spaces, individual and group, were reconstructed, with the dimensions interpreted as the red-green (RG) and the blue-yellow (BY) systems. When color configurations from the Hg-group were compared to those of the controls, they presented more fluctuations along both chromatic dimensions, indicating a statistically significant difference along the BY axis. In conclusion, the present findings confirm that color vision impairments persist in subjects that have received long-term occupational exposure to Hg-vapor although, at the time of testing, they were presenting mean urinary concentration within the normal range for non-exposed individuals. Considering the advantages of the triadic procedure in clinical evaluation of acquired color vision deficiencies, further studies should attempt to verify and/or improve its efficacy.

Preliminary Findings on the Effects of Occupational Exposure to Mercury Vapor Below Safety Levels on Visual and Neuropsychological Functions

Objective: To evaluate whether there are visual and neurophysical decrements in workers with low exposure to Hg vapor. Methods: Visual fields, contrast sensitivity, color vision, and neuropsychological functions were measured in 10 workers (32.5 +/- 8.5 years) chronically exposed to Hg vapor (4.3 +/- 2.8 years; urinary Hg concentration 22.3 +/- 9.3 mu g/g creatinine). Results: For the worst eyes, we found altered visual field thresholds, lower contrast sensitivity, and color discrimination compared with controls (P < 0.05). There were no significant differences between Hg-exposed subjects and controls on. neuropsychological tests. Nevertheless, duration of exposure was statistically correlated to verbal memory and depression scores. Conclusions: Chronic exposure to Hg vapor at currently accepted safety levels was found to be associated with visual losses but not with neuropsychological dysfunctions in the sample of workers studied. (J Occup Environ Med. 2009,51:1403-1412)

Visual field losses in workers exposed to mercury vapor

Visual field losses associated with mercury (Hg) exposure have only been assessed in patients exposed to methylmercury. Here we evaluate the automated visual field in 35 ex-workers (30 males; 44.20+/-5.92 years) occupationaly exposed to mercury vapor and 34 controls (21 males; 43.29+/-8.33 years). Visual fields were analyzed with the Humphrey Field Analyzer II (model 750i) using two tests: the standard automated perimetry (SAP, white-on-white) and the short wavelength automated perimetry (SWAP, blue-on-yellow) at 76 locations within a 27 degrees central visual field. Results were analyzed as the mean of the sensitivities measured at the fovea, and at five successive concentric rings, of increasing eccentricity, within the central field. Compared to controls, visual field sensitivities of the experimental group measured using SAP were lower for the fovea as well as for all five eccentricity rings (p<0.05). Sensitivities were significantly lower in the SWAP test (p<0.05) for four of the five extra-foveal eccentricity rings; they were not significant for the fovea (p = 0.584) or for the 15 degrees eccentricity ring (p = 0.965). These results suggest a widespread reduction of sensitivity in both visual field tests. Previous reports in the literature describe moderate to severe concentric constriction of the visual field in subjects with methylmercury intoxication measured manually with the Goldman perimeter. The present results amplify concerns regarding potential medical risks of exposure to environmental mercury sources by demonstrating significant and widespread reductions of visual sensitivity using the more reliable automated perimetry. (C) 2007 Elsevier Inc. All rights reserved.

The use of thermal manikin to evaluate interface pressure distribution

The use of a thermal buttocks manikin(1) was explored as a tool to standardize the evaluation of seat comfort. Thermal manikin buttocks were developed and calibrated thermally and anatomically to simulate the sensible heat transfer of a seated person and used to evaluate interface pressure distribution. In essence, the pressure maps of manikin buttocks with and without heating were compared to those of a seated person. The results of average pressure demonstrated that the thermal manikins have a better response in interface pressure measurement than manikins without heating.

Anti-inflammatory Effects of Aerobic Exercise in Mice Exposed to Air Pollution

VIEIRA, R. D. P., A. C. TOLEDO, L. B. SILVA, F. M. ALMEIDA, N. R. DAMACENO-RODRIGUES, E. G. CALDINI, A. B. G. SANTOS, D. H. RIVERO, D. C. HIZUME, F. D. T. Q. S. LOPES, C. R. OLIVO, H. C. CASTRO-FARIA-NETO, M. A. MARTINS, P. H. N. SALDIVA, and M. DOLHNIKOFF. Anti-inflammatory Effects of Aerobic Exercise in Mice Exposed to Air Pollution. Med. Sci. Sports Exerc., Vol. 44, No. 7, pp. 1227-1234, 2012. Purpose: Exposure to diesel exhaust particles (DEP) results in lung inflammation. Regular aerobic exercise improves the inflammatory status in different pulmonary diseases. However, the effects of long-term aerobic exercise on the pulmonary response to DEP have not been investigated. The present study evaluated the effect of aerobic conditioning on the pulmonary inflammatory and oxidative responses of mice exposed to DEP. Methods: BALB/c mice were subjected to aerobic exercise five times per week for 5 wk, concomitantly with exposure to DEP (3 mg.mL (1); 10 mu L per mouse). The levels of exhaled nitric oxide, reactive oxygen species, cellularity, interleukin 6 (IL-6), and tumor necrosis factor alpha (TNF-alpha) were analyzed in bronchoalveolar lavage fluid, and the density of neutrophils and the volume proportion of collagen fibers were measured in the lung parenchyma. The cellular density of leukocytes expressing IL-1 beta, keratinocyte chemoattractant (KC), and TNF-alpha in lung parenchyma was evaluated with immunohistochemistry. The levels of IL-1 beta, KC, and TNF-alpha were also evaluated in the serum. Results: Aerobic exercise inhibited the DEP-induced increase in the levels of reactive oxygen species (P < 0.05); exhaled nitric oxide (P < 0.01); total (P < 0.01) and differential cells (P < 0.01); IL-6 and TNF-alpha levels in bronchoalveolar lavage fluid (P < 0.05); the level of neutrophils (P < 0.001); collagen density in the lung parenchyma (P < 0.05); the levels of IL-6, KC, and TNF-alpha in plasma (P < 0.05); and the expression of IL-1 beta, KC, and TNF-alpha by leukocytes in the lung parenchyma (P < 0.01). Conclusions: We conclude that long-term aerobic exercise presents protective effects in a mouse model of DEP-induced lung inflammation. Our results indicate a need for human studies that evaluate the pulmonary responses to aerobic exercise chronically performed in polluted areas.

Variations in peak expiratory flow measurements associated to air pollution and allergic sensitization in children in Sao Paulo, Brazil

Background In the last 20 years, there has been an increase in the incidence of allergic respiratory diseases worldwide and exposure to air pollution has been discussed as one of the factors associated with this increase. The objective of this study was to investigate the effects of air pollution on peak expiratory flow (PEF) and FEV1 in children with and without allergic sensitization. Methods Ninety-six children were followed from April to July, 2004 with spirometry measurements. They were tested for allergic sensitization (IgE, skin prick test, eosinophilia) and asked about allergic symptoms. Air pollution, temperature, and relative humidity data were available. Results Decrements in PEF were observed with previous 24-hr average exposure to air pollution, as well as with 310-day average exposure and were associated mainly with PM10, NO2, and O3 in all three categories of allergic sensitization. Even though allergic sensitized children tended to present larger decrements in the PEF measurements they were not statistically different from the non-allergic sensitized. Decrements in FEV1 were observed mainly with previous 24-hr average exposure and 3-day moving average. Conclusions Decrements in PEF associated with air pollution were observed in children independent from their allergic sensitization status. Their daily exposure to air pollution can be responsible for a chronic inflammatory process that might impair their lung growth and later their lung function in adulthood. Am. J. Ind. Med. 55:10871098, 2012. (c) 2012 Wiley Periodicals, Inc.

Economic Cost of Air Pollution in Cubatao - SP Based on Health Expenses Related to Diseases of the Respiratory and Circulatory Systems

The aim of this research was to evaluate economic costs of respiratory and circulatory diseases in the municipality of Cubatao, in the state of Sao Paulo, Brazil. Data on hospital admissions and on missed working days due to hospitalization (for age group 14 to 70 years old) from the database of Sistema Unico de Sa de (SUS - Brazilian National Health System) were used. Results: Based on these data, it was calculated that R$ 22.1 million were spent in the period 2000 to 2009 due to diseases of the respiratory and circulatory systems. Part of these expenses can be directly related to the emission of atmospheric pollutants in the city. In order to estimate the costs related to air pollution, data on Cubatao were compared to data from two other municipalities that are also located at the coast side (Guaruja and Peru be), but which have little industrial activity in comparison to Cubatao. It was verified that, in both, average per capita costs were lower when compared to Cubatao, but that this difference has been decreasing in recent years.

Air pollution and health: bridging the gap from sources to health outcomes: conference summary

Air Pollution and Health: Bridging the Gap from Sources to Health Outcomes, an international specialty conference sponsored by the American Association for Aerosol Research, was held to address key uncertainties in our understanding of adverse health effects related to air pollution and to integrate and disseminate results from recent scientific studies that cut across a range of air pollution-related disciplines. The Conference addressed the science of air pollution and health within a multipollutant framework (herein "multipollutant" refers to gases and particulate matter mass, components, and physical properties), focusing on five key science areas: sources, atmospheric sciences, exposure, dose, and health effects. Eight key policy-relevant science questions integrated across various parts of the five science areas and a ninth question regarding findings that provide policy-relevant insights served as the framework for the meeting. Results synthesized from this Conference provide new evidence, reaffirm past findings, and offer guidance for future research efforts that will continue to incrementally advance the science required for reducing uncertainties in linking sources, air pollutants, human exposure, and health effects. This paper summarizes the Conference findings organized around the science questions. A number of key points emerged from the Conference findings. First, there is a need for greater focus on multipollutant science and management approaches that include more direct studies of the mixture of pollutants from sources with an emphasis on health studies at ambient concentrations. Further, a number of research groups reaffirmed a need for better understanding of biological mechanisms and apparent associations of various health effects with components of particulate matter (PM), such as elemental carbon, certain organic species, ultrafine particles, and certain trace elements such as Ni, V, and Fe(II), as well as some gaseous pollutants. Although much debate continues in this area, generation of reactive oxygen species induced by these and other species present in air pollution and the resulting oxidative stress and inflammation were reiterated as key pathways leading to respiratory and cardiovascular outcomes. The Conference also underscored significant advances in understanding the susceptibility of populations, including the role of genetics and epigenetics and the influence of socioeconomic and other confounding factors and their synergistic interactions with air pollutants. Participants also pointed out that short-and long-term intervention episodes that reduce pollution from sources and improve air quality continue to indicate that when pollution decreases so do reported adverse health effects. In the limited number of cases where specific sources or PM2.5 species were included in investigations, specific species are often associated with the decrease in effects. Other recent advances for improved exposure estimates for epidemiological studies included using new technologies such as microsensors combined with cell phone and integrated into real-time communications, hybrid air quality modeling such as combined receptor-and emission-based models, and surface observations used with remote sensing such as satellite data.

Variability of neurally-adjusted ventilatory assist (nava) compared to pressure support ventilation (psv) during the weaning phase of mechanical ventilation.

Rationale: NAVA is an assisted ventilatory mode that uses the electrical activity of the diaphragm (Edi) to trigger and cycle the ventilator, and to offer inspiratory assistance in proportion to patient effort. Since Edi varies from breath to breath, airway pressure and tidal volume also vary according to the patient's breathing pattern. Our objective was to compare the variability of NAVA with PSV in mechanically ventilated patients during the weaning phase. Methods: We analyzed the data collected for a clinical trial that compares PSV and NAVA during spontaneous breathing trials using PSV, with PS of 5 cmH2O, and NAVA, with Nava level titrated to generate a peak airway pressure equivalent to PSV of 5 cmH2O (NCT01137271). We captured flow, airway pressure and Edi at 100Hz from the ventilator using a dedicated software (Servo Tracker v2, Maquet, Sweden), and processed the cycles using a MatLab (Mathworks, USA) code. The code automatically detects the tidal volume (Vt), respiratory rate (RR), Edi and Airway pressure (Paw) on a breath-by-breath basis for each ventilatory mode. We also calculated the coefficient of variation (standard deviation, SD, divided by the mean). Results: We analyzed data from eleven patients. The mean Vt was similar on both modes (370 ±70 for Nava and 347± 77 for PSV), the RR was 26±6 for Nava and 26±7 or PSV. Paw was higher for Nava than for PSV (14±1 vs 11±0.4, p=0.0033), and Edi was similar for both modes (12±8 for Nava and 11±6 for PSV). The variability of the respiratory pattern, assessed with the coefficient of variation, was larger for Nava than for PSV for the Vt ( 23%±1% vs 15%±1%, p=0.03) and Paw (17%±1% vs 1% ±0.1%, p=0.0033), but not for RR (21% ±1% vs 16% ±8%, p=0.050) or Edi (33%±14% vs 39% ±16%,p=0.07). Conclusion: The variability of the breathing pattern is high during spontaneous breathing trials independent of the ventilatory mode. This variability results in variability of airway pressure and tidal volume, which are higher on Nava than on PSV. Our results suggest that Nava better reflects the normal variability of the breathing pattern during assisted mechanical ventilation.

Irreversible color vision losses in patients with chronic mercury vapor intoxication

This longitudinal study addresses the reversibility of color vision losses in subjects who had been occupationally exposed to mercury vapor. Color discrimination was assessed in 20 Hg-exposed patients (mean age = 42.4 +/- 6.5 years; 6 females and 14 males) with exposure to Hg vapor during 10.5 +/- 5.3 years and away from the work place (relative to 2002) for 6.8 +/- 4.2 years. During the Hg exposure or up to one year after ceasing it, mean urinary Hg concentration was 47 +/- 35.4 mu g/g creatinine. There was no information on Hg urinary concentration at the time of the first tests, in 2002 (Ventura et al., 2005), but at the time of the follow-up tests, in 2005, this value was 1.4 +/- 1.4 mu g/g creatinine for patients compared with 0.5 +/- 0.5 mu g/g creatinine for controls (different group from the one in Ventura et al. (2005)). Color vision was monocularly assessed using the Cambridge Colour Test (CCT). Hg-exposed patients had significantly worse color discrimination (p < 0.02) than controls, as evaluated by the size of MacAdam`s color discrimination ellipses and color discrimination thresholds along protan, deutan, and tritan confusion axes. There were no significant differences between the results of the study in Ventura et al. (2005) and in the present follow-up measurements, in 2005, except for worsening of the tritan thresholds in the best eye in 2005. Both chromatic systems, blue-yellow and red-green, were affected in the first evaluation (Ventura et al., 2005) and remained impaired in the follow-up testing, in 2005. These findings indicate that following a long-term occupational exposure to Hg vapor, even several years away from the source of intoxication, color vision impairment remains irreversible.

Electrophysiological evidence for impairment of contrast sensitivity in mercury vapor occupational intoxication

Contrast sensitivity (CS) was evaluated in 41 former workers from a lamp manufacturing plant who were on disability retirement due to exposure to mercury and 14 age-matched controls. The CS was measured monocularly using the sweep visual evoked potential (sVEP) paradigm at 6 spatial frequencies (0.2, 0.8, 2.0, 4.0, 15.0, and 30 cpd). Statistical difference (p < 0.05) was found between the controls and the patient right and left eyes for 2.0 and 4.0 cpd. According the results in those spatial frequencies the eyes were classified in best and worst. Statistical differences were found between the controls and the best eyes for 2.0 and 4.0 cpd and for 0.8, 2.0, and 4.0 cpd for their worst eyes. No correlation was found between CS results and the time of exposure (mean 8.9 yr +/- 4.1), time away from the mercury source (mean = 6.0 yr +/- 3.9), urinary mercury level at the time of work (mean = 40.6 mu g/g +/-36.3) or with the mercury level at the CS measurement time (mean = 1.6 mu g/g +/-1.1). We show the first evidence of a permanent impairment in CS measured objectively with the sVEP. Our data complement the previous psychophysical works reporting a diffuse impairment in the CS function showing a CS reduction in the low to middle spatial frequencies. In conclusion, non-reversible CS impairment was found in occupational exposure to mercury vapor. We suggest that CS measurement should be included in studies of the mercury effects of occupational exposure. (C) 2007 Elsevier Inc. All rights reserved.

Effect of humidity and solvent vapor phase on cellulose esters films

In the present study the effect of relative humidity (RH) during spin-coating process on the structural characteristics of cellulose acetate (CA), cellulose acetate phthalate (C-A-P), cellulose acetate butyrate (CAB) and carboxymethyl cellulose acetate butyrate (CMCAB) films was investigated by means of atomic force microscopy (AFM), ellipsometry and contact angle measurements. All polymer solutions were prepared in tetrahydrofuran (THF), which is a good solvent for all cellulose esters, and used for spin-coating at RH of (35 +/- A 5)%, (55 +/- A 5)% or (75 +/- A 5)%. The structural features were correlated with the molecular characteristics of each cellulose ester and with the balance between surface energies of water and THF and interface energy between water and THF. CA, CAB, CMCAB and C-A-P films spin-coated at RH of (55 +/- A 5)% were exposed to THF vapor during 3, 6, 9, 60 and 720 min. The structural changes on the cellulose esters films due to THF vapor exposition were monitored by means of AFM and ellipsometry. THF vapor enabled the mobility of cellulose esters chains, causing considerable changes in the film morphology. In the case of CA films, which are thermodynamically unstable, dewetting was observed after 6 min exposure to THF vapor. On the other hand, porous structures observed for C-A-P, CAB and CMCAB turned smooth and homogeneous after only 3 min exposure to THF vapor.