6,630 research outputs found
Study of mechanisms controlling the ultraviolet photochemistry of associated and polymeric systems
Vacuum ultraviolet photoionization and photodissociation of associated and polymeric systems of liquid water and alcohol
Neither Genius nor fudge : Edgar Allan Poe and Eureka
Eureka (1848) has been taken at face value as an expanded version of a lecture on cosmology that Poe gave earlier the same year. However, its seriousness as a work of science should be questioned. Its treatment of themes found in other works by Poe shows the author's unconcern for consistency, and the text unlikely to have resulted from a serious engagement with scientific argument. Instead it should be approached as a hoax: an attempt to reveal the gullibility of its readers. Poe's hoaxes relied for their effect on the trust created in readers by their recognition of generic conventions, and Eureka exploited and ridiculed public trust in cosmological lecturers such as John Bovee Dods.Eureka (1848) ha sido considerado superficialmente como una versión expandida de una conferencia sobre cosmología que Poe había dado ese mismo año. Sin embargo, la seriedad de este trabajo como un trabajo científico debería ser cuestionada. El tratamiento de algunos temas, que se encuentran en otros escritos de Poe, muestra que el autor no busca ser consistente. Entonces, el texto no parece el resultado de un interés serio por la argumentación científica. Por el contrario, debería ser considerado un engaño: un intento de revelar la credulidad de los lectores. Los engaños de Poe contaban con el hecho de que el reconocimiento de convenciones de género llevan a la confianza, y Eureka aprovecha y ridiculiza la confianza pública en conferenciantes cosmológicos como John Bovee Dods.Eureka (1848) ha estat considerat superficialment com una versió expandida d'una conferència sobre cosmologia que Poe va donar aquell mateix any. Tot i així, la serietat d'aquest text com a treball científic hauria d'ésser qüestionada. El tratament d'alguns temes, que es poden trobar a d'altres escrits de Poe, mostra que l'autor no cerca d'ésser consistent. Aleshores, el text no sembla el resultat d'un interés seriós per l'argumentació científica sinó que hauria de ser considerat un engany: un intent de revelar la credulitat dels lectors. Els enganys de Poe es basen en el fet que el reconeixement de les convencions genèriques impliquen confiança, i Eureka aprofita i ridiculitza aquesta confiança publica en conferenciants cosmològics com John Bovee Dods.Eureka 1848ko otsailean Poek kosmologiari buruz eman zuen ikastaro baten bertsio luzatutzat onartua izan da. Hala ere, obra testu zientifikoa ote den ez dago hain garbi. Poeren beste obra batzuetan ikusi da gaiak lantzerakoan ez zuela koherentziarekiko arretarik jartzen; ondorioz Eureka ezin da hartu pentsamendu zientifikoaren emaitza gisa. Iruzurra bat dela pentsatu behar da: irakurleen sinesgarritasuna salatzeko saiakera bat. Irakurleei konbentzio orokorrak aurkitzeak eragiten dien sinesgarritasunean datza, hain zuzen, Poeren txantxa. Eurekak John Bovee Dods bezalako irakurleen konfiantza erabili eta irrigarri utzi zuen ikuskera kosmologikoa ematen zela uste izan zutelako
Accuracy and bias of visual estimates of numbers, size structure and biomass of a coral reef fish
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Ionization-induced asymmetric self-phase modulation and universal modulational instability in gas-filled hollow-core photonic crystal fibers
We study theoretically the propagation of relatively long pulses with
ionizing intensities in a hollow-core photonic crystal fiber filled with a
Raman-inactive gas. Due to photoionization, previously unknown types of
asymmetric self-phase modulation and `universal' modulational instabilities
existing in both normal and anomalous dispersion regions appear. We also show
that it is possible to spontaneously generate a plasma-induced continuum of
blueshifting solitons, opening up new possibilities for pushing supercontinuum
generation towards shorter and shorter wavelengths.Comment: 5 pages, 4 figure
Direct characterisation of tuneable few-femtosecond dispersive-wave pulses in the deep UV
Dispersive wave emission (DWE) in gas-filled hollow-core dielectric
waveguides is a promising source of tuneable coherent and broadband radiation,
but so far the generation of few-femtosecond pulses using this technique has
not been demonstrated. Using in-vacuum frequency-resolved optical gating, we
directly characterise tuneable 3fs pulses in the deep ultraviolet generated via
DWE. Through numerical simulations, we identify that the use of a pressure
gradient in the waveguide is critical for the generation of short pulses.Comment: 5 pages, 4 figure
Drivers of predator killing by rural residents and recommendations for fostering coexistence in agricultural landscapes
Predators inhabiting human-dominated landscapes are vulnerable to various anthropogenic actions, including people killing them. We assess potential drivers of predator killing in an agricultural landscape in southern Chile, and discuss the implications for policies and interventions to promote coexistence. We evaluate five different types of motivation: (i) sociodemographics and household economy; (ii) livestock loss; (iii) predator encounter rates; (iv) knowledge of legal protection (all native predators are currently protected); and, (v) tolerance to livestock predation. As the killing of native predators is illegal, the prevalence of this behaviour by rural residents was estimated using a symmetrical forced-response randomised response technique (RRT), a method designed to ask sensitive questions. A total of 233 rural residents from randomly assigned sample units (4 km2) across the study region completed our questionnaire. More conspicuous species, such as hawks (Falconiformes sp), foxes (Lycalopex sp) and free-roaming domestic dogs (Canis lupus familiaris), were killed by a higher proportion of farmers than more cryptic species, like the felid güiña (Leopardus guigna), skunk (Conepatus chinga) and pumas (Puma concolor). The proportion of respondents admitting to killing predators was highest for hawks (mean= 0.46, SE= 0.08), foxes (mean= 0.29, SE= 0.08) and dogs (mean= 0.30, SE= 0.08) and lowest for güiña (mean= 0.10, SE = 0.09), which is the only species of conservation concern we examine (considered Vulnerable on the IUCN Red List). From our five motivation categories, past killing of predators was associated with higher reported predator encounter rates (guina, hawks), lower tolerance to livestock predation (hawks, dogs), higher reported livestock loss (dogs) and sociodemographics and household economy (foxes). Our results demonstrate that a one-size-fits-all approach to predator persecution is unlikely to reduce or eliminate illegal killings for the suite of species we examined. We identify and describe two main types of intervention that could foster coexistence, improvement of livestock management and domestic dog management in rural areas, as well as discussing the potential for social marketing
Spatial trends of breast and prostate cancers in the United States between 2000 and 2005
<p>Abstract</p> <p>Background</p> <p>Breast cancer in females and prostate cancer in males are two of the most common cancers in the United States, and the literature suggests that they share similar features. However, it is unknown whether the occurrence of these two cancers at the county level in the United States is correlated. We analyzed Caucasian age-adjusted county level average annual incidence rates for breast and prostate cancers from the National Cancer Institute and State Cancer Registries to determine whether there was a spatial correlation between the two conditions and whether the two cancers had similar spatial patterns.</p> <p>Results</p> <p>There was a significant correlation between breast and prostate cancers by county (r = 0.332, p < 0.001). This relationship was more pronounced when we performed a geographically-weighted regression (GWR) analysis (r = 0.552) adjusting for county unemployment rates. There was variation in the parameter estimates derived with the GWR; however, the majority of the estimates indicted a positive association. The strongest relationship between breast and prostate cancer was in the eastern parts of the Midwest and South, and the Southeastern U.S. We also observed a north-south pattern for both cancers with our cluster analyses. Clusters of counties with high cancer incidence rates were more frequently found in the North and clusters of counties with low incidence rates were predominantly in the South.</p> <p>Conclusion</p> <p>Our analyses suggest breast and prostate cancers cluster spatially. This finding corroborates other studies that have found these two cancers share similar risk factors. The north-south distribution observed for both cancers warrants further research to determine what is driving this spatial pattern.</p
Testing for HFE-related haemochromatosis
HFE-haemochromatosis is a genetic disorder resulting from mutations of the HFE gene. It primarily affects people of Northern European descent. Clinical manifestations result from the progressive deposition of iron into various organs including the liver. An elevated serum ferritin concentration greater than 300 microgram/L and a transferrin saturation of greater than 45% will identify almost all patients with HFE-haemochromatosis. HFE genotyping confirms the diagnosis. In some patients, liver biopsy may still be necessary as the degree of hepatic fibrosis has prognostic implications
Effects of acute and chronic hypohydration on tolerance to plus Gz acceleration in man. I - Physiological results
Effects of acute and chronic hypohydration on human physiological tolerance to gravity acceleratio
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