Search results for "Season"
showing 10 items of 1002 documents
Diatoms from thermal-sulphur waters of “Fiume Caldo” (North-western Sicily).
2007
The present study describes the taxonomic composition, richness and seasonal dynamics of the diatom community from thermal-sulphur waters of "Fiume Caldo" (Northwestern Sicily). The diatom flora of these waters consists of 64 taxa, showing similarities with thermal diatom communities from different geographical areas. Among the recorded taxa, Diadesmis confervacea Kütz. is a new record for Sicily. Seasonal changes in assemblage composition and richness have been recorded; the highest diversity values were observed during winter and spring, while during summer the diatom community consisted of a limited number of organisms whereas blue-green algae were quantitatively dominant. Inside the stu…
Quand l’agriculture des pays riches crée de la pauvreté
2018
L’agriculture a toujours été un secteur où les tâches peu qualifiées sont restées très pourvoyeuses de main d’oeuvre ; ce sont majoritairement les immigrés fraîchement arrivés qui s’y adonnent, les natifs délaissant ces travaux pénibles, mal payés et peu valorisants. Nous allons analyser dans cette contribution l’extrême difficulté des « saisonniers-migrants » présents en Espagne. Pour cela, nous mettrons en résonnance les parcours de deux immigrés, originaires l’un du Maroc, l’autre du Mali, pour montrer comment ils sont littéralement devenus « prisonniers » de cette agriculture, sans pouvoir se construire — ni se projeter — dans un quelconque autre avenir, cette situation ayant été amplif…
Using random networks to study the dynamics of respiratory syncytial virus (RSV) in the Spanish region of Valencia
2011
[EN] Seasonal fluctuations in the incidence of several respiratory infections are a feature of epidemiological surveys all around the world. This phenomenon is characteristic of influenza and respiratory syncytial virus pandemics. However, the explanation of the seasonal outbreaks of these diseases remains poorly understood. Many statistical studies have been carried out in order to provide a correlation of the outbreaks with climatic or social factors without achieving a definitive conclusion. Here we show that, in a random social network, self-sustained seasonal epidemics emerge as a process modulated by the infection probability and the immunity period after recovering from the infection…
The Early Spörer Minimum – A Period of Extraordinary Climate and Socio-economic Changes in Western and Central Europe
2016
Abstract. Throughout the last millennium, mankind was affected by prolonged deviations from the climate mean state. While periods like the Maunder Minimum in the 17th century have been assessed in greater detail, earlier cold periods such as the 15th century received much less attention due to the sparse information available. Based on new evidence from different sources ranging from proxy archives to model simulations, it is now possible to provide an end-to-end assessment about the climate state during an exceptionally cold period in the 15th century, the role of internal, unforced climate variability and external forcing in shaping these extreme climatic conditions, and the impacts on an…
A TEST FOR REPRODUCTIVE SEPARATION OF ALTERNATE GENERATIONS IN A BIENNIAL SPIDER, ARANEUS DIADEMATUS (ARANEAE, ARANEIDAE)
2002
In Denmark, two seemingly distinct size-classes, 3rd and 4th instar juveniles and repro- ductive adults, of Araneus diadematus are found during every breeding season in autumn, indicating a non-overlapping biennial life-cycle. We tested the hypothesis that alternate generations might experience a degree of reproductive isolation, using the distribution of nuclear (allozyme) and maternal (mtDNA) genetic markers. Individuals of a locality behaved as belonging to a random mating population, irrespective of size. No differences were found between any size-class pairs, within and between 2 yr, or among geographically distant samples. Processes that may lead to this result are discussed: the bien…
Abundance of cellular material and proteins in the atmosphere.
2005
Suspended atmospheric particles play a crucial role in any global climate scenario: They can both enforce and suppress radiative forcing. In developing climate modeling further, a deeper understanding of atmospheric aerosol is needed. Because of extreme local and temporal variations, proper incorporation of aerosols into models requires modeling of the aerosol itself. It turns out that cellular material and proteins compose up to 25% of the atmospheric aerosol. Consequently, the source strength of the biogenic aerosol in general must be corrected and should be estimated on the order of other major aerosol sources.
Changes in diets of individual Baltic ringed seals (Phoca hispida botnica) during their breeding season inferred from stable isotope analysis of mult…
2008
The stable isotope ratios (� 13 C and � 15 N) of three tissues with different metabolic rates (plasma, liver, and muscle) were used to investigate temporal variation in diet among nine individual Baltic ringed seals (Phoca hispida botnica Gmelin) from the Bothnian Bay, northeast Baltic Sea. The isotope values from plasma should reflect the most recent diet, values from liver the diet of the past weeks prior to sampling, and values from muscle should integrate diet over almost the entire breeding season of the ringed seals. In general, � 13 C values of liver were more enriched in 13 C than were those of either muscle or plasma, suggesting that the diet of the seals may have included a higher…
Estimation of the Combined Effects of Ageing and Seasonality on Mortality Risk: An Application to Spain
2021
Abstract Despite the overwhelming evidence that shows the persistence of intra-annual variations on demographic events (deaths, birth dates and migration flows), life tables are computed and provided on an annual basis. This paper develops a new estimator for estimating sub-annual death rates that, considering the exact moment of occurrence (exact age and day) of events, concurrently accounts for ageing and calendar fluctuations. This paper also shows how modelling the intra-annual variations of death rates, through specific seasonal–ageing indexes, can be used as a tool for constructing new sub-annual tables from annual tables. This new methodology is exemplified using a real database of S…
Analysis and modelling of wind speed in New York
2010
In this paper we propose an ARMA time-series model for the wind speed at a single spatial location, and estimate it on in-sample data recorded in three different wind farm regions in New York state. The data have a three-hour granularity, but based on applications to financial wind derivatives contracts, we also consider daily average wind speeds. We demonstrate that there are large discrepancies in the behaviour of daily average and three-hourly wind speed records. The validation procedure based on out-of-sample observations reflects that the proposed model is reliable and can be used for various practical applications, like, for instance, weather prediction, pricing of financial wind cont…
A dish-stirling solar concentrator coupled to a seasonal thermal energy storage system in the southern mediterranean basin: A cogenerative layout hyp…
2020
Abstract In the future, renewable energy sources will increasingly represent an efficient energy source capable of meeting the demands of residential and industrial buildings avoiding the emissions of greenhouse gases into the atmosphere. In this paper, a heat and electric power cogeneration plant implementing a field of dish-Stirling collectors, a seasonal geothermal storage and a system of water-to-water heat pumps is proposed for the first time. The cogeneration plant has been designed both to supply thermal energy to the heating system of Building 9 of the Department of Engineering in Palermo and to produce electricity. The operation of the plant has been tested by means of hourly-based…