Search results for "ozone"
showing 10 items of 300 documents
Portfolio diversification in the sovereign credit swap markets
2018
We develop models for portfolio diversification in the sovereign credit default swaps (CDS) markets and show that, despite literature findings that sovereign CDS spreads are affected by global factors, there is sufficient idiosyncratic risk to be diversified. However, we identify regime switching in the times series of CDS spreads and spread returns, and the optimal diversified strategies can be regime dependent. The developed models trade off the CVaR risk measure against expected return, consistently with the statistical properties of spreads. We consider three investment strategies suited for different CDS market participants: for investors with long positions, speculators that hold unco…
Ozone-induced reductions in below-ground biomass: an anatomical approach in potato
2010
[EN] Potato plants were grown in open-top chambers under three ozone concentrations during two complete cropping seasons (93 and 77 d in 2004 and 2005, respectively). The effects of chronic exposure to ozone on leaf anatomy, cell ultrastructure and crop yield were studied. Severe cell damage was found, even at ambient ozone levels, mainly affecting the spongy parenchyma and areas near the stomata. Damage to the cell wall caused loss of cell contact, and loss of turgor pressure due to tonoplast disintegration, contributed to cell collapse. Phloem sieve plates were obstructed by callose accumulation, and damaged mesophyll cells increased their starch stores. Tuber yield fell sharply (24–44%),…
Changes in the Constitution of Thylakoid Membranes in Spruce Needles During an Open‐top Chamber Experiment
1992
The goal of the presented paper was to study the emission effects of natural air pollutants on the protein complexes of the thylakoid membrane. The tests were carried out in the frame of a long-term experiment in which spruce trees kept in open-top chambers with unfiltered ambient-air were compared to spruce trees in chambers with purified-air. The reaction centres of photosystem I (P-700), cytochrome f, cytochrome b-563, cytochrome b-559, as well as the oxidation speed of the antennae chlorophylls were quantified. The concentrations of the cytochromes f and b-563 indicate a marked annual rhythm with decreased concentrations during the summer months. The spruce trees in chambers with ambien…
In vivo ozone exposure does not increase DNA single-strand breaks in human peripheral lymphocytes
2013
In this randomized parallel study, we examined whether an acute ozone (O3) exposure leads to increased DNA strand breaks in human lymphocytes. The groups were exposed to 0.21 ppm O3 or filtered air for two hours. 30min and 4.5 h after exposure, DNA damage was determined in isolated lymphocytes using the Fast Micromethod. There was no detectable effect after O3 exposure. We conclude that an acute O3 exposure at the tested concentration does not lead to persistent DNA damage.
Validación de los datos de radiación solar UV del Ozone Monitoring Instrument (OMI) a partir de medidas con base en tierra en la costa mediterránea
2016
<p align="justify">The erythemal UV daily dose (EDD) and the local noon UV Index (UVI) obtained from the Ozone Monitoring Instrument (OMI), on board NASA’s Aura satellite, have been validated for the period 2005-2013 using ground based measurements at 5 different sites in the Mediterranean coast: Murcia, Valencia, Palma de Mallorca, Barcelona and Rome (where only measurements of the local noon UVI were available). Ground based measurements were made using YES UVB-1 radiometers in Murcia, Valencia, Palma de Mallorca and Barcelona, and a Brewer MKIV 067 spectrophotometer in Rome. The results of the validation showed good agreement between the satellite instrument and the ground based me…
A Revision of the Nearctic Species of Hecamedoides Hendel (Diptera: Ephydridae)
2008
Abstract Species of the shore-fly genus Hecamedoides Hendel from the Nearctic Region are revised, including description of H. lattini, new species (Virginia. Stafford: Falmouth (38°19.2′N, 77°28.1′W; Rappahannock River; 9 m). To provide context and also to facilitate identification, diagnoses are provided for the tribe Discocerinini and genus in addition to a key to the genera and species, H. lattini and H. unispinosus, occurring in the New World. Diagnostic characters, especially of the male terminalia, are illustrated, and distribution maps are also provided.
Assessing environmental performance trends in the transport industry: Eco-innovation or catching-up?
2015
Abstract This paper analyses the change in environmental performance that took place in the transport industry of 38 countries between the years 1995 and 2009. Data Envelopment Analysis techniques and directional distance functions are employed to compute Luenberger productivity indicators for the change in environmental performance and its determinants, namely, environmental technical change resulting from eco-innovation and catching-up with best available environmental technologies. Eight air pollutants account for the environmental contaminants from transport activities, and these are aggregated into three main categories of environmental pressures, namely, global warming, tropospheric o…
Solar UV-B radiation affects leaf quality and insect herbivory in the southern beech tree Nothofagus antarctica
2004
We examined the effects of solar ultraviolet-B (UV-B) radiation on plant-insect interactions in Tierra del Fuego (55°S), Argentina, an area strongly affected by ozone depletion because of its proximity to Antarctica. Solar UV-B under Nothofagus antarctica branches was manipulated using a polyester plastic film to attenuate UV-B (uvb-) and an Aclar film to provide near-ambient UV-B (uvb+). The plastic films were placed on both north-facing (i.e., high solar radiation in the Southern Hemisphere) and south-facing branches. Insects consumed 40% less leaf area from north- than from south-facing branches, and at least 30% less area from uvb+ branches than from uvb-branches. The reduced herbivory …
Photocatalytic ozonation under visible light for the remediation of water effluents and its integration with an electro-membrane bioreactor
2018
Abstract Photocatalysis and photocatalytic ozonation under visible light have been applied for the purification of a complex aqueous matrix such as the grey water of Masdar City (UAE), by using N-doped brookite-rutile catalysts. Preliminary runs on 4-nitrophenol (4-NP) solutions allowed to test the reaction system in the presence of a model pollutant and to afford the relevant kinetic parameters of the process. Subsequently, the remediation of grey water effluent has been evaluated in terms of the reduction of total organic carbon (TOC) and bacterial counts. The concentration of the most abundant inorganic ionic species in the effluent has been also monitored during reaction. Photocatalytic…
First record of the alien leech Myzobdella lugubris Leidy, 1851 (Hirudinea, Piscicolidae) in the Palearctic
2018
espanolEn este estudio reportamos la aparicion de la sanguijuela Neartica Myzobdella lugubris en un cuerpo de agua salobre de la reserva natural Riserva Naturale dello Stato “Le Cesine” (Apulia, Italy). Dos especimenes de la especie fueren recolectados en el cuello y las extremidades anteriores de una tortuga de estanque europea Emys orbicularis hellenica en Octubre del 2016. La identificacion de los dos especimenes fue basada en datos morfologicos y de secuenciacion molecular. En su distribucion natural, M. lugubris es conocida por ser huesped y vector de bacterias y virus, de los cuales algunos son patogenos de gravedad en peces. En vista de los posibles efectos nocivos, que ejercen sobre…