Fog- and cloud-induced aerosol modification observed by the Aerosol Robotic Network (AERONET)

Large fine mode-dominated aerosols (submicron radius) in size distributions retrieved from the Aerosol Robotic Network (AERONET) have been observed after fog or low-altitude cloud dissipation events. These column-integrated size distributions have been obtained at several sites in many regions of the world, typically after evaporation of low-altitude cloud such as stratocumulus or fog. Retrievals with cloud-processed aerosol are sometimes bimodal in the accumulation mode with the larger-size mode often similar to 0.4-0.5 mu m radius (volume distribution); the smaller mode, typically similar to 0.12 to similar to 0.20 mu m, may be interstitial aerosol that were not modified by incorporation in droplets and/or aerosol that are less hygroscopic in nature. Bimodal accumulation mode size distributions have often been observed from in situ measurements of aerosols that have interacted with clouds, and AERONET size distribution retrievals made after dissipation of cloud or fog are in good agreement with particle sizes measured by in situ techniques for cloud-processed aerosols. Aerosols of this type and large size range (in lower concentrations) may also be formed by cloud processing in partly cloudy conditions and may contribute to the "shoulder" of larger-size particles in the accumulation mode retrievals, especially in regions where sulfate and other soluble aerosol are a significant component of the total aerosol composition. Observed trends of increasing aerosol optical depth (AOD) as fine mode radius increased suggests higher AOD in the near-cloud environment and higher overall AOD than typically obtained from remote sensing owing to bias toward sampling at low cloud fraction.

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.

Aerosols in Amazonia: Natural Biogenic Particles and Large Scale Biomass Burning Impacts.

The Large Scale Biosphere Atmosphere Experiment in Amazonia (LBA) is a long term (20 years) research effort aimed at the understanding of the functioning of the Amazonian ecosystem. In particular, the strong biosphere-atmosphere interaction is a key component looking at the exchange processes between vegetation and the atmosphere, focusing on aerosol particles. Two aerosol components are the most visible: The natural biogenic emissions of aerosols and VOCs, and the biomass burning emissions. A large effort was done to characterize natural biogenic aerosols that showed detailed organic characterization and optical properties. The biomass burning component in Amazonia is important in term of aerosol and trace gases emissions, with deforestation rates decreasing, from 27,000 Km2 in 2004 to about 5,000 Km2 in 2011. Biomass burning emissions in Amazonia increases concentrations of aerosol particles, CO, ozone and other species, and also change the surface radiation balance in a significant way. Long term monitoring of aerosols and trace gases were performed in two sites: a background site in Central Amazonia, 55 Km North of Manaus (called ZF2 ecological reservation) and a monitoring station in Porto Velho, Rondonia state, a site heavily impacted by biomass burning smoke. Several instruments were operated to measured aerosol size distribution, optical properties (absorption and scattering at several wavelengths), composition of organic (OC/EC) and inorganic components among other measurements. AERONET and MODIS measurements from 5 long term sites show a large year-to year variability due to climatic and socio-economic issues. Aerosol optical depths of more than 4 at 550nm was observed frequently over biomass burning areas. In the pristine Amazonian atmosphere, aerosol scattering coefficients ranged between 1 and 200 Mm-1 at 450 nm, while absorption ranged between 1 and 20 Mm-1 at 637 nm. A strong seasonal behavior was observed, with greater aerosol loadings during the dry season (Jul-Nov) as compared to the wet season (Dec-Jun). During the wet season in Manaus, aerosol scattering (450 nm) and absorption (637 nm) coefficients averaged, respectively, 14 and 0.9 Mm-1. Angstrom exponents for scattering were lower during the wet season (1.6) in comparison to the dry season (1.9), which is consistent with the shift from biomass burning aerosols, predominant in the fine mode, to biogenic aerosols, predominant in the coarse mode. Single scattering albedo, calculated at 637 nm, did not show a significant seasonal variation, averaging 0.86. In Porto Velho, even in the wet season it was possible to observe an impact from anthropogenic aerosol. Black Carbon was measured at a high 20 ug/m³ in the dry season, showing strong aerosol absorption. This work presents a general description of the aerosol optical properties in Amazonia, both during the Amazonian wet and dry seasons.

Laminar Displacement and Prelaminar Tissue Thickness Change after Glaucoma Surgery Imaged with Optical Coherence Tomography

PURPOSE. To study changes in lamina cribrosa position and prelaminar tissue thickness (PTT) after surgical IOP reduction in glaucoma patients. METHODS. Twenty-two patients (mean age, 71.4 years) were imaged with spectral domain optical coherence tomography (SD-OCT; 24 radial B-scans centered on the optic nerve head [ONH]) before trabeculectomy or tube shunt implantation. Follow up images were acquired 1 week, 1 month, 3 months, and 6 months postsurgery. Bruch's membrane opening (BMO), the internal limiting membrane (ILM) and the anterior laminar surface (ALS) were segmented in each radial scan with custom software. Surfaces were fitted to the ILM and ALS with the extracted three-dimesional coordinates. PTT was the distance between the ILM and ALS, perpendicular to a BMO reference plane. Serial postsurgical laminar displacement (LD), relative to the BMO reference plane, and changes in PTT were measured. Positive values indicated anterior LD. RESULTS. Mean (SD) presurgery IOP was 18.1 (6.5) mm Hg, and reduced by 4.7 (5.5), 2.4 (7.7), 7.0 (6.2), and 6.8 (7.5) mm Hg at 1 week, 1 month, 3 months, and 6 months postsurgery, respectively. At the four postsurgery time points, there was significant anterior LD (1.8 [9.5], -1.1 [8.9], 8.8 [20.2], and 17.9 [25.8] mu m) and PTT increase (1.7 [13.3], 2.4 [11.9], 17.4 [13.7], and 13.9 [18.6] mu m). LD was greater in ONHs with larger BMO area (P = 0.01) and deeper ALS (P = 0.04); however, PTT was not associated with any of the tested independent variables. CONCLUSIONS. Both anterior LD and thickening of prelaminar tissue occur after surgical IOP reduction in patients with glaucoma. (Invest Ophthalmol Vis Sci. 2012;53:5819-5826) DOI:10.1167/iovs.12-9924

NIR luminescent Er3+/Yb3+ co-doped SiO2-ZrO2 nanostructured planar and channel waveguides: Optical and structural properties

Optical and structural properties of planar and channel waveguides based on sol gel Er3+ and Yb3+ co-doped SiO2-ZrO2 are reported. Microstructured channels with high homogeneous surface profile were written onto the surface of multilayered densified films deposited on SiO2/Si substrates by a femtosecond laser etching technique. The densification of the planar waveguides was evaluated from changes in the refractive index and thickness, with full densification being achieved at 900 degrees C after annealing from 23 up to 500 min, depending on the ZrO2 content Crystal nucleation and growth took place together with densification, thereby producing transparent glass ceramic planar waveguides containing rare earth-doped ZrO2 nanocrystals dispersed in a silica-based glassy host Low roughness and crack-free surface as well as high confinement coefficient were achieved for all the compositions. Enhanced NIR luminescence of the Er3+ ions was observed for the Yb3+- codoped planar waveguides, denoting an efficient energy transfer from the Yb3+ to the Er3+ ion. (C) 2012 Elsevier B.V. All rights reserved.

Unusual macular thickness in Alport syndrome: case report

This case report describes the presence of bilateral macular atrophy in a patient with Alport syndrome and compares this finding with literature. At fundoscopy, there was a discrete circumscribed macular thinning showing intense retinal pigment epithelium color and the presence of whitish circular retinal lesions ("dots" and "flecks") at nasal mid periphery of both eyes. Optical coherence tomography showed bilateral partial atrophy of the neurosensory retina in the macula, with a greater extent in the temporal region. This case describes a rare ophthalmological finding in Alport syndrome and important to be recognized for a precise diagnosis as well as for determining visual prognosis.

Color Dependence on Thickness in Topaz Crystal from Brazil

It is well known that crystals of topaz from the Eastern Brazilian Pegmatite Province may turn blue by the irradiation with Co-60 gamma rays followed by heat treatment. Also, it is known that the sensation of color changes with the thickness of these crystals. The dependence of the color, given by 1931 CIE chromaticity coordinates, with the thickness of the crystal was analyzed. The absorbance used in the calculation of these coordinates was given by the sum of Gaussian lines. The parameters of these lines were determined through the decomposition of the optical absorption spectra in the ultraviolet and visible regions. The decomposition revealed several lines, whose assignment was made considering studies in spodumene and beryl crystals and highly accurate quantum mechanical calculations. The transmittance becomes very narrow with increasing thickness, and the CIE chromaticity coordinates converge to the borderline of the CIE Chromaticity Diagram at the wavelength of maximum transmittance. Furthermore, the purity of color increases with increasing thickness, and the dominant wavelength reaches the wavelength of maximum transmittance.

Aerosol profiling with lidar in the Amazon Basin during the wet and dry season

For the first time, multiwavelength polarization Raman lidar observations of optical and microphysical particle properties over the Amazon Basin are presented. The fully automated advanced Raman lidar was deployed 60 km north of Manaus, Brazil (2.5 degrees S, 60 degrees W) in the Amazon rain forest from January to November 2008. The measurements thus cover both the wet season (Dec-June) and the dry or burning season (July-Nov). Two cases studies of young and aged smoke plumes are discussed in terms of spectrally resolved optical properties (355, 532, and 1064 nm) and further lidar products such as particle effective radius and single-scattering albedo. These measurement examples confirm that biomass burning aerosols show a broad spectrum of optical, microphysical, and chemical properties. The statistical analysis of the entire measurement period revealed strong differences between the pristine wet and the polluted dry season. African smoke and dust advection frequently interrupt the pristine phases during the wet season. Compared to pristine wet season conditions, the particle scattering coefficients in the lowermost 2 km of the atmosphere were found to be enhanced, on average, by a factor of 4 during periods of African aerosol intrusion and by a factor of 6 during the dry (burning) season. Under pristine conditions, the particle extinction coefficients and optical depth for 532 nm wavelength were frequently as low as 10-30 Mm(-1) and <0.05, respectively. During the dry season, biomass burning smoke plumes reached to 3-5 km height and caused a mean optical depth at 532 nm of 0.26. On average during that season, particle extinction coefficients (532 nm) were of the order of 100 Mm(-1) in the main pollution layer (up to 2 km height). Angstrom exponents were mainly between 1.0 and 1.5, and the majority of the observed lidar ratios were between 50-80 sr.

Quantification of Retinal Neural Loss in Patients with Neuromyelitis Optica and Multiple Sclerosis with or without Optic Neuritis Using Fourier-Domain Optical Coherence Tomography

PURPOSE. We compared retinal nerve fiber layer (RNFL) and macular thickness measurements in patients with multiple sclerosis (MS) and neuromyelitis optica (NMO) with or without a history of optic neuritis, and in controls using Fourier-domain (FD) optical coherence tomography (OCT). METHODS. Patients with MS (n = 60), NMO (n = 33), longitudinal extensive transverse myelitis (LETM, n = 28) and healthy controls (n = 41) underwent ophthalmic examination, including automated perimetry, and FD-OCT RNFL and macular thickness measurements. Five groups of eyes were compared: MS with or without previous optic neuritis, NMO, LETM, and controls. Correlation between OCT and visual field (VF) findings was investigated. RESULTS. With regard to most parameters, RNFL and macular thickness measurements were significantly smaller in eyes of each group of patients compared to controls. MS eyes with optic neuritis did not differ significantly from MS eyes without optic neuritis, but measurements were smaller in NMO eyes than in all other groups. RNFL (but not macular thickness) measurements were significantly smaller in LETM eyes than in controls. While OCT abnormalities were correlated significantly with VF loss in NMO/LETM and MS, the correlation was much stronger in the former. CONCLUSIONS. Although FD-OCT RNFL and macular thickness measurements can reveal subclinical or optic neuritis-related abnormalities in NMO-spectrum and MS patients, abnormalities are predominant in the macula of MS patients and in RFNL measurements in NMO patients. The correlation between OCT and VF abnormalities was stronger in NMO than in MS, suggesting the two conditions differ regarding structural and functional damage. (ClinicalTrials.gov number, NCT01024985.) Invest Ophthalmol Vis Sci. 2012;53:3959-3966) DOI:10.1167/iovs.11-9324

Nerve fiber layer in glaucomatous hemifield loss: a case-control study with time- and spectral-domain optical coherence tomography

Purpose: To evaluate the retinal nerve fiber layer measurements with time-domain (TD) and spectral-domain (SD) optical coherence tomography (OCT), and to test the diagnostic ability of both technologies in glaucomatous patients with asymmetric visual hemifield loss. Methods: 36 patients with primary open-angle glaucoma with visual field loss in one hemifield (affected) and absent loss in the other (non-affected), and 36 age-matched healthy controls had the study eye imaged with Stratus-OCT (Carl Zeiss Meditec Inc., Dublin, California, USA) and 3 D OCT-1000 (Topcon, Tokyo, Japan). Peripapillary retinal nerve fiber layer measurements and normative classification were recorded. Total deviation values were averaged in each hemifield (hemifield mean deviation) for each subject. Visual field and retinal nerve fiber layer "asymmetry indexes" were calculated as the ratio between affected versus non-affected hemifields and corresponding hemiretinas. Results: Retinal nerve fiber layer measurements in non-affected hemifields (mean [SD] 87.0 [17.1] mu m and 84.3 [20.2] mu m, for TD and SD-OCT, respectively) were thinner than in controls (119.0 [12.2] mu m and 117.0 [17.7] mu m, P<0.001). The optical coherence tomography normative database classified 42% and 67% of hemiretinas corresponding to non-affected hemifields as abnormal in TD and SD-OCT, respectively (P=0.01). Retinal nerve fiber layer measurements were consistently thicker with TD compared to SD-OCT. Retinal nerve fiber layer thickness asymmetry index was similar in TD (0.76 [0.17]) and SD-OCT (0.79 [0.12]) and significantly greater than the visual field asymmetry index (0.36 [0.20], P<0.001). Conclusions: Normal hemifields of glaucoma patients had thinner retinal nerve fiber layer than healthy eyes, as measured by TD and SD-OCT. Retinal nerve fiber layer measurements were thicker with TD than SD-OCT. SD-OCT detected abnormal retinal nerve fiber layer thickness more often than TD-OCT.

Structure-function Relationships Using the Cirrus Spectral Domain Optical Coherence Tomograph and Standard Automated Perimetry

Purpose: To evaluate the relationship between glaucomatous structural damage assessed by the Cirrus Spectral Domain OCT (SDOCT) and functional loss as measured by standard automated perimetry (SAP). Methods: Four hundred twenty-two eyes (78 healthy, 210 suspects, 134 glaucomatous) of 250 patients were recruited from the longitudinal Diagnostic Innovations in Glaucoma Study and from the African Descent and Glaucoma Evaluation Study. All eyes underwent testing with the Cirrus SDOCT and SAP within a 6-month period. The relationship between parapapillary retinal nerve fiber layer thickness (RNFL) sectors and corresponding topographic SAP locations was evaluated using locally weighted scatterplot smoothing and regression analysis. SAP sensitivity values were evaluated using both linear as well as logarithmic scales. We also tested the fit of a model (Hood) for structure-function relationship in glaucoma. Results: Structure was significantly related to function for all but the nasal thickness sector. The relationship was strongest for superotemporal RNFL thickness and inferonasal sensitivity (R(2) = 0.314, P < 0.001). The Hood model fitted the data relatively well with 88% of the eyes inside the 95% confidence interval predicted by the model. Conclusions: RNFL thinning measured by the Cirrus SDOCT was associated with correspondent visual field loss in glaucoma.

Techniques for measuring aerosol attenuation using the Central Laser Facility at the Pierre Auger Observatory

The Pierre Auger Observatory in Malargüe, Argentina, is designed to study the properties of ultra-high energy cosmic rays with energies above 1018 eV. It is a hybrid facility that employs a Fluorescence Detector to perform nearly calorimetric measurements of Extensive Air Shower energies. To obtain reliable calorimetric information from the FD, the atmospheric conditions at the observatory need to be continuously monitored during data acquisition. In particular, light attenuation due to aerosols is an important atmospheric correction. The aerosol concentration is highly variable, so that the aerosol attenuation needs to be evaluated hourly. We use light from the Central Laser Facility, located near the center of the observatory site, having an optical signature comparable to that of the highest energy showers detected by the FD. This paper presents two procedures developed to retrieve the aerosol attenuation of fluorescence light from CLF laser shots. Cross checks between the two methods demonstrate that results from both analyses are compatible, and that the uncertainties are well understood. The measurements of the aerosol attenuation provided by the two procedures are currently used at the Pierre Auger Observatory to reconstruct air shower data.

Optical storage in azobenzene-containing epoxy polymers processed as Langmuir Blodgett films

In this study, azocopolymers containing different main-chain segments have been synthesized with diglycidyl ether of bisphenol A (DGEBA, DER 332, n=0.03) and the azochromophore Disperse Orange 3 (DO3) cured with twomonoamines, viz. benzylamine (BA) and m-toluidine (MT). The photoinduced birefringence was investigated in films produced with these azopolymers using the spin coating (SC) and Langmuir Blodgett (LB) techniques. In the LB films, birefringence increased with the content of azochromophore and the film thickness, as expected. The nanostructured nature of the LB films led to an enhanced birefringence and faster dynamics in the writing process, compared to the SC films. In summary, the combination of azocopolymers and the LBmethod may allow materials with tuned properties for various optical applications, including in biological systems were photoisomerization may be used to trigger actions such as drug delivery.