602 research outputs found
Considerations for Evaluating Ultraviolet Radiation-Induced Genetic Damage Relative to Antarctic Ozone Depletion
Springtime ozone depletion over the Antarctic results in increased UVB in local marine environments. It has been established that decreases in primary productivity occur with decreases in ozone concentrations, but the impact of increased UVB on the functioning and stability of the ecosystem has not yet been determined. Very little has been done to evaluate the potential for genetic damage caused by the increase in UVB, and this type of damage is most significant relative to the fitness and maintenance of populations. An essential problem in evaluating genotoxic effects is the lack of appropriate techniques to sample and quantify genetic damage in field populations under ambient UVB levels. In addition, it is currently not feasible to estimate exposure levels for organisms in their natural habitats
Vanadium (ÎČ-(Dimethylamino)ethyl)cyclopentadienyl Complexes with Diphenylacetylene Ligands
Reduction of the V(III) (ÎČ-(dimethylamino)ethyl)cyclopentadienyl dichloride complex [η5:η1-C5H4(CH2)2NMe2]VCl2(PMe3) with 1 equiv of Na/Hg yielded the V(II) dimer {[η5:η1-C5H4(CH2)2NMe2]V(”-Cl)}2 (2). This compound reacted with diphenylacetylene in THF to give the V(II) alkyne adduct [η5:η1-C5H4(CH2)2NMe2]VCl(η2-PhCâĄCPh). Further reduction of 2 with Mg in the presence of diphenylacetylene resulted in oxidative coupling of two diphenylacetylene groups to yield the diamagnetic, formally V(V), bent metallacyclopentatriene complex [η5:η1-C5H4(CH2)2NMe2]V(C4Ph4).
En studie om varsling, HR-ledelse og organisasjonskultur
FormÄlet med denne oppgaven er Ä undersÞke sammenhengen mellom temaene varsling, HRledelse
og organisasjonskultur. Vi er spesielt interessert i Ă„ belyse fĂžlgende problemstilling:
"Hvordan kan HR-ledere tilrettelegge for en Ă„pen organisasjonskultur som gir rom for
forsvarlig varsling?". Basert pÄ problemstillingen har vi ogsÄ utviklet en hypotese: "Vi tror at
en Ă„pen organisasjonskultur vil bidra til at HR-ledere vil fange opp problemer, fĂžr det
eskalerer til en varslingssak"
For Ä undersÞke oppgavens formÄl har vi benyttet en kvalitativ metode med en fenomenologisk
tilnÊrming. Datainnsamlingen er i form av dybde intervju med vÄrt strategiske utvalg, som
bestÄr av fire HR-ledere fra fire ulike organisasjoner. VÄr empiriske datainnsamling
sammenliknes i analysen med teori innenfor organisasjonskultur og ledelse, samt den norske
lov, med hovedvekt pÄ arbeidsmiljÞloven.
Hoved essensen i oppgavens er hvorvidt HR-lederne aktivt bruker styringsverktÞy for Ä pÄvirke
de ansattes atferd og derav tilrettelegge for en Ă„pen organisasjonskultur. Vi ser i lys av denne
studien at HR-lederne er bevisst pÄ deres pÄvirkningskraft, samt hvor avgjÞrende
organisasjonens kultur er ved behovet for Ä varsle. Vi har ogsÄ avdekket at HR-ledere kan
bruke fem generelle effekter som organisasjonskultur har pÄ atferd. Ved Ä forankre dette i
selskapets retningslinjer og kulturinnhold, kan HR-lederne tilrettelegge for en Ă„pen
organisasjonskultur som gir rom for forsvarlig varsling.
VĂ„r teori og empiri viser at det det er lettere for ansatte Ă„ ta opp kritikk og stille kritiske
spÞrsmÄl i en organisasjon som preges av Äpenhet. Dette kan fÞre til at problemene lÞses idet
de oppstÄr og derfor ikke eskaleres til en varslingssak
Vannkvalitet i verneomrÄder i Nordland: Kvitblikvatnet og Vallvatnet i Fauske og Altervatnet og Storvatnet pÄ DÞnna
To av de undersÞkte innsjÞene ligger i Altervatn naturreservat pÄ DÞnna (Altervatnet og Vallvatnet), mens de to andre ligger i Fauskeidet naturreservat i Fauske. Alle fire innsjÞer var kalkrike. InnsjÞene pÄ DÞnna var i tillegg pÄvirket av havsalter, og bunnfargete organiske forbindelser fra omliggende myrer. InnsjÞene pÄ DÞnna var tydelig pÄvirket av tilfÞrsler av fosfor og nitrogen. Det anbefales Ä undersÞke om menneskelig pÄvirkning (landbruk) eller naturlige kilder (fugl, nÊringsrik berggrunn) er de viktigste Ärsakene til dette. Altervatnet er eutrof (nÊringsrik) mens de tre andre innsjÞen er mesotrofe (middels nÊringsrike)
Drivers of change in Chinaâs energy-related COâ emissions
CO2 emissions are of global concern because of climate change. China has become the largest CO2 emitter in the world and presently accounts for 30% of global emissions. Here, we analyze the major drivers of energy-related CO2 emissions in China from 1978 when the reform and opening-up policy was launched. We find that 1) there has been a 6-fold increase in energy-related CO2 emissions, which was driven primarily (176%) by economic growth followed by population growth (16%), while the effects of energy intensity (â79%) and carbon intensity (â13%) slowed the growth of carbon emissions over most of this period; 2) energy-related CO2 emissions are positively related to per capita gross domestic product (GDP), population growth rate, carbon intensity, and energy intensity; and 3) a portfolio of command-and-control policies affecting the drivers has altered the total emission trend. However, given the major role of China in global climate change mitigation, significant future reductions in Chinaâs CO2 emissions will require transformation toward low-carbon energy systems
Daphniaperformance on diets containing different combinations of high-quality algae, heterotrophic bacteria, and allochthonous particulate organic matter
Filter-feeding zooplankton in lakes feed on a mixture of phytoplankton, bacteria, and terrestrial particles and the proportions and nutritional value of these components can be highly variable. However, the extent to which food quality interacts with food quantity in affecting overall zooplankton performance is not yet fully resolved. Here we performed laboratory feeding experiments to test how the performance of the unselective filter feederDaphnia galeatawas affected if various quantities of high-quality food (the phytoplanktonRhodomonas) were diluted with low-quality food such as heterotrophic bacteria (Pseudomonas) or terrestrial detritus particles (t-POM) from the riparian zone of a boreal forest stream. We hypothesised: that increased proportions of bacteria and t-POM in the diet will lead to decreased survival, somatic growth; and reproduction ofDaphniadespite the presence of phytoplankton; that these effects are more pronounced for t-POM than for heterotrophic bacteria; and that this response is stronger when phytoplankton availability is low. Increasing the concentrations ofPseudomonasaffectedDaphniasurvival, growth, and reproduction negatively whenRhodomonaswas available at intermediate (0.37 mgC/L) and high (0.55 mgC/L) quantities. WhenRhodomonasquantity was low (0.22 mgC/L), the addition ofPseudomonasgenerally resulted in betterDaphniaperformance except at very high concentrations of the bacterium relative toRhodomonas. In contrast, the addition of t-POM was detrimental for overallDaphniaperformance at allRhodomonasconcentrations. Daphniaperformance was best described by a model including the interaction between food quality and quantity, with stronger negative effects onDaphniawhen high-quality food was supplemented with t-POM than withPseudomonas. The results indicate that the ability of zooplankton to use low-quality food is affected by the concurrent availability of high-quality food. Furthermore, food sources that can be used but do not fulfil dietary requirements of grazers (e.g. bacteria), may still provide nutritional benefits as long as other complementary food components are available in sufficient quantities to compensate for biochemical deficiencies. Therefore, we conclude that heterotrophic bacteria, but not peat layer t-POM, can be an important component of zooplankton diets in boreal lakes, especially if the concentration of phytoplankton is low
Impaired synaptic function is linked to cognition in Parkinson's disease
OBJECTIVE:
Cognitive impairment is frequent in Parkinson's disease, but the underlying mechanisms are insufficiently understood. Because cortical metabolism is reduced in Parkinson's disease and closely associated with cognitive impairment, and CSF amyloidâÎČ species are reduced and correlate with neuropsychological performance in Parkinson's disease, and amyloidâÎČ release to interstitial fluid may be related to synaptic activity; we hypothesize that synapse dysfunction links cortical hypometabolism, reduced CSF amyloidâÎČ, and presynaptic deposits of αâsynuclein. We expect a correlation between hypometabolism, CSF amyloidâÎČ, and the synapse relatedâmarkers CSF neurogranin and αâsynuclein.
METHODS:
Thirty patients with mildâtoâmoderate Parkinson's disease and 26 healthy controls underwent a clinical assessment, lumbar puncture, MRI, 18FâfludeoxyglucoseâPET, and a neuropsychological test battery (repeated for the patients after 2 years).
RESULTS:
All subjects had CSF amyloidâÎČ 1â42 within normal range. In Parkinson's disease, we found strong significant correlations between cortical glucose metabolism, CSF AÎČ, αâsynuclein, and neurogranin. All PET CSF biomarkerâbased cortical clusters correlated strongly with cognitive parameters. CSF neurogranin levels were significantly lower in mildâtoâmoderate Parkinson's disease compared to controls, correlated with amyloidâÎČ and αâsynuclein, and with motor stage. There was little change in cognition after 2 years, but the cognitive tests that were significantly different, were also significantly associated with cortical metabolism. No such correlations were found in the control group.
INTERPRETATION:
CSF AÎČ, αâsynuclein, and neurogranin concentrations are related to cortical metabolism and cognitive decline. Synaptic dysfunction due to AÎČ and αâsynuclein dysmetabolism may be central in the evolution of cognitive impairment in Parkinson's disease
Combined Effects of UVR and Temperature on the Survival of Crab Larvae (Zoea I) from Patagonia: The Role of UV-Absorbing Compounds
The aim of our study was to assess the combined impact of UVR (280â400 nm) and temperature on the first larval stage (Zoea I) of three crab species from the Patagonian coast: Cyrtograpsus altimanus, C. angulatus, and Leucippa pentagona. We determined the survival response of newly hatched Zoea I after being exposed for 8â10 h under a solar simulator (Hönle SOL 1200) at 15 and 20 °C. There was no mortality due to Photosynthetic Active Radiation (PAR, 400â700 nm) or ultraviolet-A radiation (UV-A, 315â400 nm), and all the observed mortality was due to ultraviolet-B radiation (UV-B, 280â315 nm). The data of larval mortality relative to exposure time was best fit using a sigmoid curve. Based on this curve, a threshold (Th) and the lethal dose for 50% mortality (LD50) were determined for each species. Based on the Th and LD50, C. altimanus was found to be the most resistant species, while L. pentagona was found to be the most sensitive to UV-B. For both species of Cyrtograpsus, mortality was significantly lower at 20 °C than at 15 °C; however, no significant differences between the two temperature treatments were found in L. pentagona. Bioaccumulation of UV-absorbing compounds in the gonads and larvae of C. altimanus, and to a lesser extent in C. angulatus, might have contributed for counteracting the impact of UV-B. However, most of the resilience to UV-B observed with the increase in temperature might be due to an increase in metabolic activity caused by a repair mechanism mediated by enzymes
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