Psychosocial and occupational risk perception among health care workers: a Moroccan multicenter study.

International audience

Análise da silvicultura na bacia hidrográfica do rio Jaguarão (Brasil-Uruguai) : diagnóstico para a gestão geoambiental em bacia transfronteiriça

Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Humanas, Departamento de Geografia, 2015.

Wellbeing and occupational risk perception among health care workers: a multicenter study in Morocco and France

International audience

Immune modulation by vitamin D and its relevance to food allergy

Apart from its classical function in bone and calcium metabolism, vitamin D is also involved in immune regulation and has been linked to various cancers, immune disorders and allergic diseases. Within the innate and adaptive immune systems, the vitamin D receptor and enzymes in monocytes, dendritic cells, epithelial cells, T lymphocytes and B lymphocytes mediate the immune modulatory actions of vitamin D. Vitamin D insufficiency/deficiency early in life has been identified as one of the risk factors for food allergy. Several studies have observed an association between increasing latitude and food allergy prevalence, plausibly linked to lower ultraviolet radiation (UVR) exposure and vitamin D synthesis in the skin. Along with mounting epidemiological evidence of a link between vitamin D status and food allergy, mice and human studies have shed light on the modulatory properties of vitamin D on the innate and adaptive immune systems. This review will summarize the literature on the metabolism and immune modulatory properties of vitamin D, with particular reference to food allergy.

Converse Bergmann cline in a eucalyptus herbivore, paropsis atomaria olivier (coleoptera: chrysomelidae) : phenotypic plasticity or local adaptation?

Aim To measure latitude-related body size variation in field-collected Paropsis atomaria Olivier (Coleoptera: Chrysomelidae) individuals and to conduct common-garden experiments to determine whether such variation is due to phenotypic plasticity or local adaptation. Location Four collection sites from the east coast of Australia were selected for our present field collections: Canberra (latitude 35°19' S), Bangalow (latitude 28°43' S), Beerburrum (latitude 26°58' S) and Lowmead (latitude 24°29' S). Museum specimens collected over the past 100 years and covering the same geographical area as the present field collections came from one state, one national and one private collection. Methods Body size (pronotum width) was measured for 118 field-collected beetles and 302 specimens from collections. We then reared larvae from the latitudinal extremes (Canberra and Lowmead) to determine whether the size cline was the result of phenotypic plasticity or evolved differences (= local adaptation) between sites. Results Beetles decreased in size with increasing latitude, representing a converse Bergmann cline. A decrease in developmental temperature produced larger adults for both Lowmead (low latitude) and Canberra (high latitude) individuals, and those from Lowmead were larger than those from Canberra when reared under identical conditions. Main conclusions The converse Bergmann cline in P. atomaria is likely to be the result of local adaptation to season length.

Seasonal Variation in Measured Solar Ultraviolet Radiation Exposure of Adults in Subtropical Australia

Generating accurate population-specific public health messages regarding sun protection requires knowledge about seasonal variation in sun exposure in different environments. To address this issue for a subtropical area of Australia, we used polysulphone badges to measure UVR for the township of Nambour (26° latitude) and personal UVR exposure among Nambour residents who were taking part in a skin cancer prevention trial. Badges were worn by participants for two winter and two summer days. The ambient UVR was approximately three times as high in summer as in winter. However, participants received more than twice the proportion of available UVR in winter as in summer (6.5%vs 2.7%, P < 0.05), resulting in an average ratio of summer to winter personal UVR exposure of 1.35. The average absolute difference in daily dose between summer and winter was only one-seventh of a minimal erythemal dose. Extrapolating from our data, we estimate that ca. 42% of the total exposure received in the 6 months of winter (June–August) and summer (December–February) is received during the three winter months. Our data show that in Queensland a substantial proportion of people’s annual UVR dose is obtained in winter, underscoring the need for dissemination of sun protection messages throughout the year in subtropical and tropical climates.

Evidence of a latitudinal gradient in spider diversity in Australian cotton

The most common explanation for species diversity increasing towards the tropics is the corresponding increase in habitats (spatial heterogeneity). Consequently, a monoculture (like cotton in Australia) which is grown along a latitudinal gradient, should have the same degree of species diversity throughout its range. We tested to see if diversity in a dominant cotton community (spiders) changed with latitude, and if the community was structurally identical in different parts of Australia. We sampled seven sites extending over 20 degrees of latitude. At each site we sampled 1-3 fields 3-5 times during the cotton growing season using pitfall traps and beatsheets, recording all the spiders collected to family. We found that spider communities in cotton are diverse, including a large range of foraging guilds, making them suitable for a conservation biological control programme. We also found that spider diversity increased from high to low latitudes, and the communities were different, even though the spiders were in the same monocultural habitat. Spider beatsheet communities around Australia were dominated by different families, and responded differently to seasonal changes, indicating that different pest groups would be targeted at different locations. These results show that diversity can increase from high to low latitudes, even if spatial heterogeneity is held constant, and that other factors external to the cotton crop are influencing spider species composition. Other models which may account for the latitudinal gradient, such as non-equilibrium regional processes, are discussed.

Limiting States Of Internal Wave Rays

Existing models of baroclinic tides are based upon the "traditional approximation'', i. e., neglect of the horizontal component of the Earth's rotation, leading to a well- known conclusion that no freely propagating internal waves can exist beyond the critical latitude and the wave rays are symmetric to the vertical. However, recent studies have contended that the situation may change if both the vertical and horizontal components of the Earth's rotation are taken into account. With the full account of the Coriolis force, characteristics of the internal wavefield generated by tidal flow over uneven topography are investigated. It is found that "nontraditional effects'' profoundly change not only the dynamics of internal waves but also the rate at which the barotropic tidal energy is fed into the internal wavefield. Discarding the traditional approximation, internal waves are proved to be able to generate poleward of the critical latitude, rays of which are no longer symmetric and the limiting values of ray angles become greater or less than 90 degrees, depending on the local latitude and the direction of ray. More importantly, in contrast to the predictions of models based upon the traditional approximation, a substantial conversion occurs in the situations when stratification is so weak that the buoyancy frequency is below the tidal one.

Ecological condition of coastal ocean waters along the U.S. Western Continental Shelf: 2003

Executive Summary: The western National Coastal Assessment (NCA-West) program of EPA, in conjunction with the NOAA National Ocean Service (NOS), conducted an assessment of the status of ecological condition of soft sediment habitats and overlying waters along the western U.S. continental shelf, between the target depths of 30 and 120 m, during June 2003. NCA-West and NOAA/NOS partnered with the West Coast states (Washington (WA), Oregon (OR), and California (CA)), and the Southern California Coastal Water Research Project (SCCWRP) Bight ’03 program to conduct the survey. A total of 257 stations were sampled from Cape Flattery, WA to the Mexican border using standard methods and indicators applied in previous coastal NCA projects. A key study feature was the incorporation of a stratified-random sampling design with stations stratified by state and National Marine Sanctuary (NMS) status. Each of the three states was represented by at least 50 random stations. There also were a total of 84 random stations located within NOAA’s five NMSs along the West Coast including the Olympic Coast NMS (OCNMS), Cordell Bank NMS (CBNMS), Gulf of Farallones NMS (GFNMS), Monterey Bay NMS (MBNMS), and Channel Islands NMS (CINMS). Collection of flatfish via hook-and-line for fish-tissue contaminant analysis was successful at 50 EMAP/NCA-West stations. Through a collaboration developed with the FRAM Division of the Northwest Fisheries Science Center, fish from an additional 63 stations in the same region and depth range were also analyzed for fish-tissue contaminants. Bottom depth throughout the region ranged from 28 m to 125 m for most stations. Two slightly deeper stations from the Southern California Bight (SCB) (131, 134 m) were included in the data set. About 44% of the survey area had sediments composed of sands (< 20% silt-clay), about 47% was composed of intermediate muddy sands (20-80% silt-clay), and about 9% was composed of muds (> 80% silt-clay). The majority of the survey area (97%) had relatively low percent total organic carbon (TOC) levels of < 2%, while a small portion (< 1%) had high TOC levels (> 5%), in a range potentially harmful to benthic fauna. Salinity of surface waters for 92% of the survey area were > 31 psu, with most stations < 31 psu associated with the Columbia River plume. Bottom salinities ranged only between 31.6 and 34.4 psu. There was virtually no difference in mean bottom salinities among states or between NMS and non-NMS stations. Temperatures of surface water (range 8.5 -19.9 °C) and bottom water (range 5.8 -14.7 °C) averaged several degrees higher in CA in comparison to WA and OR. The Δσt index of watercolumn stratification indicated that about 31% of the survey area had strong vertical stratification of the water column. The index was greatest for waters off WA and lowest for CA waters. Only about 2.6 % of the survey area had surface dissolved oxygen (DO) concentrations ≤ 4.8 mg/L, and there were no values below the lower threshold (2.3 mg/L) considered harmful to the survival and growth of marine animals. Surface DO concentrations were higher in WA and OR waters than in CA, and higher in the OC NMS than in the CA sanctuaries. An estimated 94.3% of the area had bottom-water DO concentrations ≤ 4.8 mg/L and 6.6% had concentrations ≤ 2.3 mg/L. The high prevalence of DO from 2.3 to 4.8 mg/L (85% of survey area) is believed to be associated with the upwelling of naturally low DO water across the West Coast shelf. Mean TSS and transmissivity in surface waters (excluding OR due to sample problems) were slightly higher and lower, respectively, for stations in WA than for those in CA. There was little difference in mean TSS or transmissivity between NMS and non-NMS locations. Mean transmissivity in bottom waters, though higher in comparison to surface waters, showed little difference among geographic regions or between NMS and non-NMS locations. Concentrations of nitrate + nitrite, ammonium, total dissolved inorganic nitrogen (DIN) and orthophosphate (P) in surface waters tended to be highest in CA compared to WA and OR, and higher in the CA NMS stations compared to CA non-sanctuary stations. Measurements of silicate in surface waters were limited to WA and CA (exclusive of the SCB) and showed that concentrations were similar between the two states and approximately twice as high in CA sanctuaries compared to OCNMS or nonsanctuary locations in either state. The elevated nutrient concentrations observed at CA NMS stations are consistent with the presence of strong upwelling at these sites at the time of sampling. Approximately 93% of the area had DIN/P values ≤ 16, indicative of nitrogen limitation. Mean DIN/P ratios were similar among the three states, although the mean for the OCNMS was less than half that of the CA sanctuaries or nonsanctuary locations. Concentrations of chlorophyll a in surface waters ranged from 0 to 28 μg L-1, with 50% of the area having values < 3.9 μg L-1 and 10% having values > 14.5 μg L-1. The mean concentration of chlorophyll a for CA was less than half that of WA and OR locations, and concentrations were lowest in non-sanctuary sites in CA and highest at the OCNMS. Shelf sediments throughout the survey area were relatively uncontaminated with the exception of a group of stations within the SCB. Overall, about 99% of the total survey area was rated in good condition (<5 chemicals measured above corresponding effect range low (ERL) concentrations). Only the pesticides 4,4′-DDE and total DDT exceeded corresponding effect range-median (ERM) values, all at stations in CA near Los Angeles. Ten other contaminants including seven metals (As, Cd, Cr, Cu, Hg, Ag, Zn), 2-methylnaphthalene, low molecular weight PAHs, and total PCBs exceeded corresponding ERLs. The most prevalent in terms of area were chromium (31%), arsenic (8%), 2-methylnaphthalene (6%), cadmium (5%), and mercury (4%). The chromium contamination may be related to natural background sources common to the region. The 2-methylnaphthalene exceedances were conspicuously grouped around the CINMS. The mercury exceedances were all at non-sanctuary sites in CA, particularly in the Los Angeles area. Concentrations of cadmium in fish tissues exceeded the lower end of EPA’s non-cancer, human-health-risk range at nine of 50 EMAP/NCA-West and nine of 60 FRAM groundfish-survey stations, including a total of seven NMS stations in CA and two in the OCNMS. The human-health guidelines for all other contaminants were only exceeded for total PCBs at one station located in WA near the mouth of the Columbia River. Benthic species richness was relatively high in these offshore assemblages, ranging from 19 to 190 taxa per 0.1-m2 grab and averaging 79 taxa/grab. The high species richness was reflected over large areas of the shelf and was nearly three times greater than levels observed in estuarine samples along the West Coast (e.g NCA-West estuarine mean of 26 taxa/grab). Mean species richness was highest off CA (94 taxa/grab) and lower in OR and WA (55 and 56 taxa/grab, respectively). Mean species richness was very similar between sanctuary vs. non-sanctuary stations for both the CA and OR/WA regions. Mean diversity index H′ was highest in CA (5.36) and lowest in WA (4.27). There were no major differences in mean H′ between sanctuary vs. nonsanctuary stations for both the CA and OR/WA regions. A total of 1,482 taxa (1,108 to species) and 99,135 individuals were identified region-wide. Polychaetes, crustaceans and molluscs were the dominant taxa, both by percent abundance (59%, 17%, 12% respectively) and percent species (44%, 25%, 17%, respectively). There were no major differences in the percent composition of benthic communities among states or between NMSs and corresponding non-sanctuary sites. Densities averaged 3,788 m-2, about 30% of the average density for West Coast estuaries. Mean density of benthic fauna in the present offshore survey, averaged by state, was highest in CA (4,351 m-2) and lowest in OR (2,310 m-2). Mean densities were slightly higher at NMS stations vs. non-sanctuary stations for both the CA and OR/WA regions. The 10 most abundant taxa were the polychaetes Mediomastus spp., Magelona longicornis, Spiophanes berkeleyorum, Spiophanes bombyx, Spiophanes duplex, and Prionospio jubata; the bivalve Axinopsida serricata, the ophiuroid Amphiodia urtica, the decapod Pinnixa occidentalis, and the ostracod Euphilomedes carcharodonta. Mediomastus spp. and A. serricata were the two most abundant taxa overall. Although many of these taxa have broad geographic distributions throughout the region, the same species were not ranked among the 10 most abundant taxa consistently across states. The closest similarities among states were between OR and WA. At least half of the 10 most abundant taxa in NMSs were also dominant in corresponding nonsanctuary waters. Many of the abundant benthic species have wide latitudinal distributions along the West Coast shelf, with some species ranging from southern CA into the Gulf of Alaska or even the Aleutians. Of the 39 taxa on the list of 50 most abundant taxa that could be identified to species level, 85% have been reported at least once from estuaries of CA, OR, or WA exclusive of Puget Sound. Such broad latitudinal and estuarine distributions are suggestive of wide habitat tolerances. Thirteen (1.2%) of the 1,108 identified species are nonindigenous, with another 121 species classified as cryptogenic (of uncertain origin), and 208 species unclassified with respect to potential invasiveness. Despite uncertainties of classification, the number and densities of nonindigenous species appear to be much lower on the shelf than in the estuarine ecosystems of the Pacific Coast. Spionid polychaetes and the ampharetid polychaete Anobothrus gracilis were a major component of the nonindigenous species collected on the shelf. NOAA’s five NMSs along the West Coast of the U.S. appeared to be in good ecological condition, based on the measured indicators, with no evidence of major anthropogenic impacts or unusual environmental qualities compared to nearby nonsanctuary waters. Benthic communities in sanctuaries resembled those in corresponding non-sanctuary waters, with similarly high levels of species richness and diversity and low incidence of nonindigenous species. Most oceanographic features were also similar between sanctuary and non-sanctuary locations. Exceptions (e.g., higher concentrations of some nutrients in sanctuaries along the CA coast) appeared to be attributable to natural upwelling events in the area at the time of sampling. In addition, sediments within the sanctuaries were relatively uncontaminated, with none of the samples having any measured chemical in excess of ERM values. The ERL value for chromium was exceeded in sediments at the OCNMS, but at a much lower percentage of stations (four of 30) compared to WA and OR non-sanctuary areas (31 of 70 stations). ERL values were exceeded for arsenic, cadmium, chromium, 2- methylnaphthalene, low molecular weight PAHs, total DDT, and 4,4′-DDE at multiple sites within the CINMS. However, cases where total DDT, 4,4′-DDE, and chromium exceeded the ERL values were notably less prevalent at CINMS than in non-sanctuary waters of CA. In contrast, 2-methylnaphthalene above the ERL was much more prevalent in sediments at the CINMS compared to non-sanctuary waters off the coast of CA. While there are natural background sources of PAHs from oil seeps throughout the SCB, this does not explain the higher incidence of 2-methylnaphthalene contamination around CINMS. Two stations in CINMS also had levels of TOC (> 5%) potentially harmful to benthic fauna, though none of these sites exhibited symptoms of impaired benthic condition. This study showed no major evidence of extensive biological impacts linked to measured stressors. There were only two stations, both in CA, where low numbers of benthic species, diversity, or total faunal abundance co-occurred with high sediment contamination or low DO in bottom water. Such general lack of concordance suggests that these offshore waters are currently in good condition, with the lower-end values of the various biological attributes representing parts of a normal reference range controlled by natural factors. Results of multiple linear regression, performed using full model procedures to test for effects of combined abiotic environmental factors, suggested that latitude and depth had significant influences on benthic variables regionwide. Latitude had a significant inverse influence on all three of the above benthic variables, i.e. with values increasing as latitude decreased (p< 0.01), while depth had a significant direct influence on diversity (p < 0.001) and inverse effect on density (p <0.01). None of these variables varied significantly in relation to sediment % fines (at p< 0.1), although in general there was a tendency for muddier sediments (higher % fines) to have lower species richness and diversity and higher densities than coarser sediments. Alternatively, it is possible that for some of these sites the lower values of benthic variables reflect symptoms of disturbance induced by other unmeasured stressors. The indicators in this study included measures of stressors (e.g., chemical contaminants, eutrophication) that are often associated with adverse biological impacts in shallower estuarine and inland ecosystems. However, there may be other sources of humaninduced stress in these offshore systems (e.g., bottom trawling) that pose greater risks to ambient living resources and which have not been captured. Future monitoring efforts in these offshore areas should include indicators of such alternative sources of disturbance. (137pp.) (PDF contains 167 pages)

Estresse no trabalho e pressão arterial: reflexões metodológicas sobre linearidade e operacionalização da exposição

O modelo demanda-controle proposto por Karasek caracteriza as situações de estresse no ambiente laboral que é definido pela alta exigência no trabalho resultante da combinação do efeito da demanda psicológica no trabalho (estressores) e moderadores do estresse, especialmente a capacidade de tomar decisões (controle). Existem diversas formas de operacionalizar a exposição (alta exigência no trabalho) descritas na literatura. No entanto, não há consenso sobre qual a melhor operacionalização. Outra questão negligenciada pela maioria dos autores é a forma funcional da curva exposição-resposta ou não linearidade da associação. Entre os desfechos avaliados em estudos sobre os efeitos do estresse no trabalho, usando o modelo demanda-controle, estão as doenças cardiovasculares, como a hipertensão arterial. Contudo, os resultados relatados parecem conflitantes sobre a associação entre o estresse no trabalho e a hipertensão arterial. Os objetivos deste trabalho são estudar a associação entre o estresse no trabalho e aumento da pressão arterial/hipertensão arterial usando as diferentes formas de operacionalização do estresse no trabalho e avaliar a curva exposição-resposta quanto à linearidade. O trabalho é um estudo seccional desenvolvido na população do Estudo Pró-Saúde que é composta por servidores públicos de uma universidade no Rio de Janeiro. Modelos de regressão usando diferentes distribuições foram usados para estimar a associação entre a alta exigência no trabalho e a pressão arterial/hipertensão arterial. Funções não lineares foram utilizadas para investigar a linearidade da associação entre a exposição e os desfechos. Os resultados sugerem que a relação entre a dimensão controle e a pressão arterial seja não linear. Foram observadas associações significativas entre alta exigência no trabalho e pressão arterial sistólica e diastólica para algumas formas de operacionalização da exposição, quando analisados separadamente. No entanto, quando analisadas de forma conjunta por meio do modelo de resposta bivariada não foi encontrada associação. Também não foi encontrada associação entre a alta exigência no trabalho e hipertensão arterial para nenhuma forma de operacionalização da exposição. Os modelos estatísticos com melhor ajuste foram aqueles em que a exposição foi operacionalizada por meio de quadrantes gerados pela mediana de cada uma das dimensões e de forma dicotômica com termo de interação entre demanda psicológica e controle. Neste estudo estas foram as formas mais adequadas de operacionalização. Os resultados também mostram que a associação entre a dimensão controle e a pressão arterial é não linear. Conclui-se que não há garantia de linearidade da associação entre estresse no trabalho e pressão arterial e que essa associação pode ser influenciada pela forma de operacionalização da exposição e do desfecho ou da estratégia de modelagem.

Lack of latitudinal trends in wood anatomy of Dodonaea viscosa (Sapindaceae), a species with a worldwide distribution

Latitudinal or altitudinal variation in several anatomical characters of wood is common for woody dicotyledonous genera with a wide distribution, but whether such variation exists at the species level is disputed. Latitudinal and altitudinal trends in wood anatomy of Dodonaea viscosa were studied, using 102 samples collected between 41.2degrees S and 33.3degrees N latitude and 7-2750 in altitude. We studied variation in four quantitative features: vessel element length, fiber length, vessel frequency, and tangential vessel diameter. Ontogenetic trends were minimal with a slight decrease or increase in the innermost stem and were negligible among the studied specimens. Throughout the distributional range of the species, no latitudinal trends were detected in either the Northern or Southern Hemispheres, Altitudinal trends were also nonexistent, except for two features in specimens from China and Japan. Absence of latitudinal or altitudinal trends in this widely distributed species suggests that in some species the species-level variation in wood anatomy is not controlled by ecological gradients.

太阳辐射对热层和电离层变化性的影响

Solar ultraviolet (UV) radiation at wavelengths less than 400 nm is an important source of energy for aeronomic processes throughout the solar system. Solar UV photons are absorbed in planetary atmospheres, as well as throughout the heliosphere, via photodissociation of molecules, photoionization of molecules and atoms, and photoexcitation toexcitation including resonance scattering. In this paper, the solar irradiances data measured by TIMED SEE, as well as the solar proxies such as F10.7 and Mg II, thermosphere neutral density of CHAMP measurements and topside ionospheric plasmas densities from DMSP, are used to analyze solar irradiance effects on the variabilities of the thermosphere and the ionosphere. First, thermosphere densities near 410 km altitude are analyzed for solar irradiance variability effects during the period 2002-2004. Correlations between the densities and the solar irradiances for different spectral lines and wavelength ranges reveal significantly different characteristics. The density correlates remarkably well with all the selected solar irradiances except the lower chromospheric O I (130.4 nm) emission. Among the chosen solar proxies, the Mg II core-to-wing ratio index, EUV (30-120 nm) and F10.7 show the highest correlations with the density for short-term (< ~27 days) variations. For both long- (> ~27 days) and short-term variations, linear correlation coefficients exhibit a decreasing trend from low latitudes towards high latitudes. The density variability can be effectively modeled (capturing 71% of the variance) using multiple solar irradiance indices, including F10.7, SEUV (the EUV 30-120 nm index), and SFUV (the FUV 120-193 nm index), in which a lag time of 1 day was used for both F10.7 and SEUV, and 5 days for SFUV. In our regression formulation SEUV has the largest contribution to the density variation (40%), with the F10.7 having the next largest contribution (32%) and SFUV accounting for the rest (28%). Furthermore, a pronounced period of about 27.2 days (mean period of the Sun's rotation) is present in both density and solar irradiance data of 2003 and 2004, and a pronounced period of about 54.4 days (doubled period of the solar rotation) is also revealed in 2004. However, soft X-ray and FUV irradiances did not present a pronounced 54.4 day period in 2004, in spite of their high correlation with the densities. The Ap index also shows 54-day periodicities in 2004, and magnetic activity, together with solar irradiance, affects the 54-day variation in density significantly. In addition, NRLMSISE00, DTM-2000 and JB2006 model predictions are compared with density measurements from CHAMP to assess their accuracy, and the results show that these models underestimate the response of the thermosphere to variations induced by solar rotation. Next, the equatorial topside ionospheric plasmas densities Ni are analyzed for solar irradiance variability effects during the period 2002-2005. Linear correlations between Ni and the solar irradiances for different wavelength ranges reveal significantly different characteristics. XUV (0-35 nm) and EUV (115-130 nm) show higher correlation with Ni for the long-term variations, whereas EUV (35-115 nm) show higher correlation for the short-term variations. Moreover, partial correlation analysis shows that the long-term variations of Ni are affected by both XUV (0-35 nm) and EUV (35-115 nm), whereas XUV (0-35 nm) play a more important role; the short-term variations of Ni are mostly affected by EUV (35-115 nm). Furthermore, a pronounced period of about 27 days is present in both Ni and solar irradiance data of 2003 and 2004, and a pronounced period of about 54 days is also revealed in 2004. Finally, prompted by previous studies that have suggested solar EUV radiation as a means of driving the semiannual variation, we investigate the intra-annual variation in thermosphere neutral density near 400 km during 2002-2005. The intra-annual variation, commonly referred to as the ‘semiannual variation’, is characterized by significant latitude structure, hemispheric asymmetries, and inter-annual variability. The magnitude of the maximum yearly difference, from the yearly minimum to the yearly maximum, varies by as much as 60% from year to year, and the phases of the minima and maxima also change by 20-40 days from year to year. Each annual harmonic of the intra-annual variation, namely, annual, semiannual, ter-annual and quatra-annual, exhibits a decreasing trend from 2002 through 2005 that is correlated with the decline in solar activity. In addition, some variations in these harmonics are correlated with geomagnetic activity, as represented by the daily mean value of Kp. Recent empirical models of the thermosphere are found to be deficient in capturing most of the latitude dependencies discovered in our data. In addition, the solar flux and geomagnetic activity proxies that we have employed do not capture some latitude and inter-annual variations detected in our data. It is possible that these variations are partly due to other effects, such as seasonal-latitudinal variations in turbopause altitude (and hence O/N2 composition) and ionosphere coupling processes that remain to be discovered in the context of influencing the intra-annual variations depicted here. Our results provide a new dataset to challenge and validate thermosphere-ionosphere general circulation models that seek to delineate the thermosphere intra-annual variation and to understand the various competing mechanisms that may contribute to its existence and variability. We furthermore suggest that the term “intra-annual” variation be adopted to describe the variability in thermosphere and ionosphere parameters that is well-captured through a superposition of annual, semiannual, ter-annual, and quatra-annual harmonic terms, and that “semiannual’ be used strictly in reference to a pure 6-monthly sinusoidal variation. Moreover, we propose the term “intra-seasonal” to refer to those shorter-term variations that arise as residuals from the above Fourier representation.

中低纬电离层暴的统计分析与经验建模

As a key issue of ionospheric weather study, systemic studies on ionospheric storms can not only further improve our understanding of the response of the ionosphere to solar and geomagnetic disturbances, but also help us to reveal the chemical, dynamic and electro-dynamic mechanisms during storms. Empirical modelling for regional ionospheric storm is also very useful, because it can provide us with tools and references for the forecasting and further practical application of ionospheric activity. In this thesis, we focus on describing and forecasting of ionospheric storms at middle and low latitudes. The main points of my investigations are listed as follows. (1) By using magnetic storms during the period over 50 years, the dependence of the type, onset time and time delay of the ionospheric storms on magnetic latitude, season and local time at middle and low latitudes in the East-Asian sector are studied. The results show that the occurrences of the types of ionospheric disturbances differ in latitude and season. The onset of the ionospheric storms depends on local time. At middle latitudes, most negative phase onsets are within the local time interval from night to early morning, and they rarely occurred in the local noon and afternoon sectors. At low latitudes, positive phases commence most frequently in the daytime sector as well as pre-midnight sector. The average time delays for both the positive and negative ionospheric storms increase with descending latitudes. The time delay has significant dependence on the local time of main phase onset (MPO). The time delay of positive response is shorter for daytime MPO and longer for night-time MPO, whereas the opposite applies for negative response. (2) Based on some previous researches, a primary empirical model for mid-latitude ionospheric disturbance is set up. By fitting to the observed data, we get a high accuracy with a mean RMSE of only 12-14% in summer and equinox. The model output has been compared with the output of STORM model, and the results show that, our model is much better than STORM in summer and a little better for some mid-latitude stations at equinox. Especially, for the type of two-step geomagnetic storm, our model can present twice descending of foF2 very well. In addition, our model can forecast positive ionospheric storms.

The ecology of the song thrush, Turdus philomelos Br., in Ireland

Over the last 30 years, western European Song Thrush populations have declined with the steepest decline recorded on British farmland. Changes in agricultural practices have been implicated in these population declines. Ireland is an agriculturally dominated landscape but changes in agriculture here have occurred on a relatively slower rate and scale. Little is known about the ecology of the Song Thrush in Ireland, even though it is not classified as a species of conservation concern here. Some decline is thought to have occurred but the current breeding population appears to be stable and widespread. In light of these facts, this study investigated various aspects of Song Thrush ecology in relation to the Irish landscape from 2001-2003. The breeding season extended from mid March to late June, where mean clutch size was 4.1 and number of fledglings was 3.7. There were very few third broods. Daily nest survival rates were calculated for egg stage 0.9362, incubation stage 0.9505 and nestling stage 0.6909. Most nest failures were due to avian predation at both egg and chick stages. Most nests were located 1.3 -2.4m from the ground at trees, bushes or hedgerow. Clutch size was significantly higher on farmland than garden & parkland and woodland, and the number of fledglings was significantly lower in nests in trees than hedgerow and bush sites. Daily nest fail rates were significantly higher at tree sites and partly concealed nests. Nesting areas had significantly denser vertical vegetation than non-nesting areas. Mercury and the organochlorine HEOD were the most common contaminants in Song Thrush eggs and livers. However concentrations and occurrence were low and of no apparent biological or ecological concern. The presence of breeding Song Thrushes was influenced by mixed surrounding farmland, the absence of grass surrounding farmland, ditches especially wet ones, tall dense vegetation and trimmed boundaries. Song Thrush winter densities were predicted by ditches, with wet or dry, low thin vegetation and untrimmed boundaries. Winter densities were almost double that of the breeding season, probably due to the arrival and passage of migrating Song Thrushes through the country, especially in November. Changes in Irish agriculture did not differ significantly in areas of Song Thrush breeding population stability and apparent decline during 1970 1990. Even though the current breeding population heavily uses farmland, woodland, human and scrub habitats are more preferred. Nevertheless no farmland habitat was avoided, highlighting a positive relationship between breeding Song Thrushes and Irish agriculture. This appears to be in contrast with findings between breeding Song Thrushes and British agriculture. Theses findings are compared with other studies and possible influences by agricultural intensification, climate, latitude and insular syndrome are discussed. Implications for conservation measures are considered, especially for areas of decline. Even though Song Thrushes are currently widespread and stable here, future environmental consequences of longer-term changes in Irish agriculture and perhaps climate change remain to be seen.

Mediterranean marine copepods: basin-scale trends of the calanoid Centropages typicus

The Mediterranean Sea is located in a crossroad of mid-latitude and subtropical climatic modes that enhance contrasting environmental conditions over both latitudinal and longitudinal ranges. Here, we show that the large-scale environmental forcing is reflected in the basin scale trends of the adult population of the calanoid copepod Centropages typicus. The species is distributed over the whole Mediterranean basin, and maximal abundances were found in the north-western basin associated to oceanic fronts, and in the Adriatic Sea associated to shallow and semi enclosed waters. The peak of main abundances of C. typicus correlates with the latitudinal temperature gradient and the highest seasonal abundances occurred in spring within the 14–18°C temperature window. Such thermal cline may define the latitudinal geographic region where C. typicus seasonally dominates the >200 μm-sized spring copepod community in the Mediterranean Sea. The approach used here is generally applicable to investigate the large-scale spatial patterns of other planktonic organisms and to identify favourable environmental windows for population development.