Role Of Photos Research Articles

Cascade energy reemission by the iodine atom irradiated by 0.01–100 keV photons. Role of photo- and cascade-produced electrons in radiosensitization using iodine-containing agents

Cascade decays of single K to O vacancies in an isolated iodine atom are simulated by straightforward construction of the cascade decay trees. Cascade-emitted electron and photon spectra are calculated and analyzed to determine the portions of energies (a) absorbed by the iodine atom after ionization and complete cascade relaxation, (b) emitted by cascade electrons, (c) emitted by cascade photons. These quantities are calculated as functions of incident photon energy following photoionization of the iodine atom in the 0.01–100 keV energy range. Cascade electrons and photoelectrons are shown to be principal energy transmitters from an ionized iodine atom to the environment. Presented data are relevant for developing the strategies of photon activation radiation therapy when iodine is used as a radiosensitizing agent.

HIV-associated photodermatitis in African populations.

Photosensitive dermatoses are seen in 5% of HIV-infected persons. These include drug- and chemical-induced photoallergic and phototoxic reactions, chronic actinic dermatitis of HIV, photo lichenoid drug eruptions, and porphyria. Data on photodermatitis in HIV are limited to case reports and series. The pathogenesis is not completely understood and includes a th2 phenotype in HIV which results in impaired barrier function and resultant allergen sensitisation as well as immune dysregulation. The objective of this manuscript is to review the literature on the clinical phenotype, pathogenesis, role of photo and patch testing, outcomes, and treatment of photodermatitis in HIV in an African population.

Cascade energy reemission after inner-shell ionization of atomic gold. Role of photo- and cascade-produced electrons in radiosensitization using gold-containing agents

A method of straightforward construction and analysis of the cascade decay trees is applied to calculate photon and electron spectra emitted upon the cascade de-excitation of single inner-shell vacancies in the gold atom produced by photoionization. The energy acquired by the gold atom upon photoionization is split into the following channels: i) energy absorbed by the gold atom itself, ii) energy carried away by the cascade electrons, and iii) energy carried away by the cascade photons. The energies absorbed through channels i–iii are analyzed for the cascade decay of each single vacancy in O to K shells, and presented as functions of incident photon energies based on calculated partial photoionization cross sections. Energy reemitted through channels ii and iii in the cases of O-, N-, M-, L-, and K-ionization make, respectively, 47–60%, 55–69%, 85–89%, 94–96%, and 99% of the initially acquired energy. Cascade-produced electrons and photons eventually transfer their energy to the medium which lays the base for using gold-containing compounds and gold nanoparticles as radiosensitizing agents in radiotherapy. Cascade-produced electrons, as well as photoelectrons, are found to be the principal transmitters of energy to atoms of the environment in the vicinity of the sites of initial ionization. Their relative role in possible radiosensitizing effect is analyzed on the incident photon energy range of 0.01–1000 keV.

Role of photo- and biodegradation of two PAHs on leaves: Modelling the impact on air quality ecosystem services provided by urban trees

Urban trees provide important ecosystem services, including air quality improvement. Polycyclic aromatic hydrocarbons (PAHs) are among the most important pollutants in air, due to their elevated concentrations and toxicity. Plants can act as filters of PAHs and as “chemical reactors” for pollutant removal, therefore reducing air concentrations. Here, the first assessment of photo- vs. biodegradation of PAHs on leaves of urban trees is presented. A dynamic air-vegetation-soil model (SoilPlusVeg) was improved to simulate the fate of two representative PAHs with contrasting physico-chemical properties (phenanthrene and benzo[a]pyrene). Simulations were performed for two different environmental scenarios from Italy (Como and Naples), selected for their dissimilar meteorological parameters, plant species and emission levels. The effect of photo- and biodegradation on leaf concentrations and fluxes towards air and soil was investigated comparing deciduous (maple, cornel and hazelnut) and evergreen (holm oak) broadleaf woods. The results showed that biodegradation in the phyllosphere could not be neglected when evaluating the ecosystem services provided by urban trees, as this process contributed significantly to the reductions (up to 25% on average) in PAH leaf concentrations and fluxes to air and soil; however, the reductions revealed ample variations with time (up to more than two orders of magnitude) showing the dependence on meteorological parameters, air compartment structure, as well as type of woods. These findings permitted to improve the ecological realism of the simulations and obtain more accurate results when predicting organic contaminant uptake and release by plant leaves, including potential for food chain transfer and long-range transport.

The role of photo and temperature regimes in the formation of potato plant productivity in vitro

The role of photo and temperature regimes in the formation of potato plant productivity in vitro

Bridging worlds: community led visual methods amidst climate change related disasters in Australia

Abstract Background In February 2009 Victorian rural communities were hit by the worst bushfires in Australian history. Immediately we evaluated community groups preparing residents for bushfires. Ten years on, we are one of the few teams to evaluate medium to long term community recovery using multiple methods. As climate change becomes more visible, the frequency and intensity of disasters will increase so communities, governments and service providers need more evidence based strategies and policies. We explore how participant led visual methods provide new knowledge. Methods In study 1 participants in 3 of 7 focus groups in peoples’ homes spontaneously brought photos for us to examine before the discussions. In another participants spoke of the importance of photos they took at the time. We returned to the field to interview people in their homes about the meaning and role of photos. Results Participants wanted to inform us-as outsiders-of the awe and enormity of the fires. They created a visual record to communicate with key interest groups and ward off complacity as memories receded. Photos helped them construct timelines and meanings of the intense fires. Crucially, they recorded recovery and rebuilding in both the built and natural environments. Over the next ten years we chronicled stories from community led visual methods of communication, recovery and empowerment. We incorporated into qualitative methods participant led tours of their environments, with visual methods. Visual data collected by communities focused more strongly on the natural environment than researcher led verbal methods. Conclusions Visual sociology changes as technology provides participants in research with increased access to, and control over, visual methods. These changes can rebalance power relations between qualitative researchers and participants and bridge visual and verbal methods; crafting striking stories to influence those Australian policies unresponsive to climate change. Key messages Technological change enables participants in qualitative research to initiate visual methods to build bridges between them and researchers. Community led visual methods provide new types of data useful for theory and knowledge translation.

The role of photo- and thermal degradation for CO<sub>2</sub> and CO fluxes in an arid ecosystem

Abstract. Recent studies have suggested the potential importance of abiotic degradation in arid ecosystems. In this study, the role of photo- and thermal degradation in ecosystem CO2 and CO exchange is assessed. A field experiment was performed in Italy using an FTIR-spectrometer (Fourier Transform Infrared) coupled to a flux gradient system and to flux chambers. In a laboratory experiment, field samples were exposed to different temperatures and radiation intensities. No photodegradation-induced CO2 and CO fluxes of in literature suggested magnitudes were found in the field nor in the laboratory study. In the laboratory, we measured CO2 and CO fluxes that were derived from thermal degradation. In the field experiment, CO uptake and emission have been measured and are proposed to be a result of biological uptake and abiotic thermal degradation-production. We suggest that previous studies, addressing direct photodegradation, have overestimated the role of photodegradation and observed fluxes might be due to thermal degradation, which is an indirect effect of radiation. The potential importance of abiotic decomposition in the form of thermal degradation, especially for arid regions, should be considered in future studies.

Sherwood Anderson: A Photographic Gallery

The role of photos in biographical study, especially of twentiethcentury American authors, has become increasingly important in recent years, particularly with the ready availability of the collections at Yale University, the University of California, and many other libraries. Unfortunately, however, there are many more accumulations in the possession of private individuals, collectors, and families that are not as accessible.