Search results for "sif"
showing 10 items of 30916 documents
Terrestrial carbohydrates support freshwater zooplankton during phytoplankton deficiency
2016
Article
Long-term changes in pigmentation of arctic Daphnia provide potential for reconstructing aquatic UV exposure
2016
Abstract Despite the biologically damaging impacts of solar ultraviolet radiation (UV) in nature, little is known about its natural variability, forcing mechanisms, and long-term effects on ecosystems and organisms. Arctic zooplankton, for example the aquatic keystone genus Daphnia (Crustacea, Cladocera) responds to biologically damaging UV by utilizing photoprotective strategies, including pigmentation. We examined the preservation and content of UV-screening pigments in fossil Daphnia remains (ephippia) in two arctic lake sediment cores from Cornwallis Island (Lake R1), Canada, and Spitsbergen (Lake Fugledammen), Svalbard. The aims were to document changes in the degree of UV-protective p…
Phosphorus limitation enhances parasite impact: feedback effects at the population level
2014
Background Nutrient deficiency affects the growth and population dynamics of consumers. Endoparasites can be seen as consumers that drain carbon (C) or energy from their host while simultaneously competing for limiting resources such as phosphorus (P). Depending on the relative demands of the host and the parasite for the limiting nutrient, intensified resource competition under nutrient limitation can either reduce the parasite’s effect on the host or further reduce the fitness of the nutrient-limited host. So far, knowledge of how nutrient limitation affects parasite performance at the host population level and how this affects the host populations is limited. Results We followed the popu…
Oxidative stress biomarkers in the copepod Limnocalanus macrurus from the northern Baltic Sea : effects of hydrographic factors and chemical contamin…
2015
Expansión urbana del Área Metropolitana de Valencia en el periodo 1984-2011 a partir de imágenes Landsat TM y ETM+
2015
La expansión urbana acelerada producida en décadas recientes en las grandes áreas metropolitanas como Valencia conlleva importantes impactos ambientales, entre ellos la impermeabilización o "sellado antropogénico" del suelo y la pérdida de espacios naturales de gran valor paisajístico. Este trabajo analiza la evolución de la cobertura artificial en el Área Metropolitana de Valencia (AMV) en el periodo 1984-2011 a partir de imágenes Landsat TM y ETM+, validadas a partir de datos SIOSE de mayor resolución espacial. Los resultados muestran, con una precisión del 71%, un aumento de la superficie artificial en el AMV de 8000 ha en dicho periodo, lo que supone un incremento del 10% del suelo sell…
Evolución de la oferta exportable en Santander, Colombia 2000-2012: Un análisis a través del índice Herfindahl Hirschmann
2016
Este documento tuvo como objetivo analizar la evolución de la oferta exportadora de Santander entre el año 2000 y 2012, revisando los patrones de concentración o diversificación. Para ello utilizó como metodología el cálculo del índice de Herfindahl-Hirschmann. Los hallazgos encontrados establecen que la oferta exportable se ha concentrado por lo que las políticas diseñadas para promover la diversificación de producto no han tenido los efectos esperados y es necesario el diseño de nuevos lineamientos para tal fin.
Chemical Composition of the Essential Oil of Bupleurum Fontanesii (Apiaceae) Growing Wild in Sicily and its Activity on Microorganisms Affecting Hist…
2016
Hydrodistillation of the flowers (BpFl) of and fruits (BpFr) of Bupleurum fontanesii Guss. ex Caruel gave two oils that were analyzed by GC and GC-MS. The main components were α-elemol (16.7%), caryophyllene oxide (16.4%) and heptacosane (15.9%) in BpFl, and spathulenol (16.8%), caryophylladienol I (13.2%) and α-elemol (12.8%) in BpFr. A good antimicrobial activity against several microorganisms, including Bacillus subtilis, Staphylococcus aureus, Fusarium oxysporum and Aspergillus niger, all infesting historical art craft, was also determined.
Chemical composition and biological activity of the essential oil of Ballota hispanica (L.) Benth. growing wild in Sicily
2015
Ballota L. comprises several relevant species largely used for their excellent therapeutic properties. Ballota hispanica (L.) Benth. is widely used in herbal medicine, and it is sold in herbalist shops for its sedative and antispasmodic properties. Considering its traditional medicinal use and the lack of scientific studies on the volatile components of this species as well as on its biological activities, in this study the chemical composition of the essential oil from aerial parts of B. hispanica, collected in Sicily, was evaluated by gas chromatography and gas chromatographyâmass spectrometry. α-Elemol was the most abundant component of the oil (10.9%), followed by α-ylangene (8.5%),…
L'armement à l'âge du Bronze final en Europe tempérée (XVIe -IXe siècles av. J.-C.) : éléments dispersés d'une « panoplie de guerrier » ?
2022
L'étude de la forme et de l'ornementation de l'armement offensif et défensif de l'âge du Bronze indique une standardisation des productions suivant des traditions qui varient selon la région et la période considérées. L'homogénéité de ces objets au sein d'un espace donné montre l'adhésion des utilisateurs de ces objets à une communauté partageant une même norme et identifiable par la possession d'objets à l'identité visuelle commune, qui n'est d'ailleurs pas limitée au cadre de l'armement. La forme et les décors standardisés de ces armes constituent un marqueur culturel-certains utilisateurs n'hésitant pas à modifier des pièces importées afin de les adapter aux habitudes locales-et révèlent…
Atkritumu apsaimniekošanas tiesiskās problēmas ārstniecības iestādēs.
2019
Bakalaura darba tēma ir „Atkritumu apsaimniekošanas tiesiskās problēmas ārstniecības iestādēs”. Darba ietvaros raksturotas ārstniecības iestāžu atkritumu apsaimniekošanas tiesiskās problēmas, analizējot Latvijas Republikas un Eiropas Savienības normatīvos aktus, izmantojot problēmas raksturojošo literatūru, publikācijas, tiesu praksi, kā arī autora praktisko pieredzi darbā ārstniecības iestādē. Darba mērķis ir izpētīt atkritumu apsaimniekošanas ārstniecības iestādēs aktuālās tiesiskās problēmas, analizēt atkritumu apsaimniekošanas normatīvo regulējumu un izvērtēt to ietekmi uz praktisko atkritumu apsaimniekošanu ārstniecības iestādē. Darbā autors sniegs atkritumu apsaimniekošanas ārstniecīb…