267 research outputs found

    Numerical Approaches to Non-Destructive Depth Profiling by Variable Angle X-Ray Photoelectron Spectroscopy

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    Variable angle x-ray photoelectron spectroscopy (VAXPS), also known as angle-resolved x-ray photoelectron spectroscopy (ARXPS), is a method which can be used to depth profile the near surface region non-destructively. The intensity variation with angle of a given energy level in a sample contains the complete information about the concentration profile of the photoionized component in the depth probed. It has been shown that the intensity is the Laplace transform of the concentration profile. Theoretically it should be possible to uniquely determine the concentration profile as the inverse Laplace transform of the intensity data. After a brief background sketch, the numerical approaches which have been used to solve the inverse Laplace transform problem in VAXPS are discussed

    Health care for the Mexican Mennonites in Canada

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    © Canadian Nurses Association. Reproduced with permission. Further reproduction is prohibited.The basic story of Canadian Mennonites is well known: During the centuries since the founding of the Mennonite church in Holland in the 1500s, religious persecution has led to group migration throughout Europe and to North America. Mennonites who came to Canada settled mainly in southern Ontario and the western provinces, where they maintained their religious practices, language, education and agrarian lifestyle. Less well known is that, in the 1920s, when the Canadian government mandated that all schools must use the provincial school curricula, some conservative Mennonites chose to leave Canada for Mexico, where they had been promised religious and educational freedom.Ye

    Ames collaborative study of cosmic ray neutrons

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    The results of a collaborative study to define both the neutron flux and the spectrum more precisely and to develop a dosimetry package that can be flown quickly to altitude for solar flare events are described. Instrumentation and analysis techniques were used which were developed to measure accelerator-produced radiation. The instruments were flown in the Ames Research Center high altitude aircraft. Neutron instrumentation consisted of Bonner spheres with both active and passive detector elements, threshold detectors of both prompt-counter and activation-element types, a liquid scintillation spectrometer based on pulse-shape discrimination, and a moderated BF3 counter neutron monitor. In addition, charged particles were measured with a Reuter-Stokes ionization chamber system and dose equivalent with another instrument. Preliminary results from the first series of flights at 12.5 km (41,000 ft) are presented, including estimates of total neutron flux intensity and spectral shape and of the variation of intensity with altitude and geomagnetic latitude

    Western Kentucky University Libraries, Preparing Information Literate Students at WKU: Report of the Task Force on Universal Information Literacy

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    Purpose: The Task Force on Universal Information Literacy was formed in the fall of 2010 and charged with reviewing the advisability and viability of providing information literacy instruction to every student at WKU

    Long‐Distance Natal Dispersal Is Relatively Frequent and Correlated with Environmental Factors in a Widespread Raptor

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    Dispersal is a critical process influencing population dynamics and responses to global change. Long‐distance dispersal (LDD) can be especially important for gene flow and adaptability, although little is known about the factors influencing LDD because studying large‐scale movements is challenging and LDD tends to be observed less frequently than shorter‐distance dispersal (SDD). We sought to understand patterns of natal dispersal at a large scale, specifically aiming to understand the relative frequency of LDD compared to SDD and correlates of dispersal distances. We used bird banding and encounter data for American kestrels (Falco sparverius) to investigate the effects of sex, migration strategy, population density, weather, year and agricultural land cover on LDD frequency, LDD distance and SDD distance in North America from 1961 to 2015. Nearly half of all natal dispersal (48.9%) was LDD (classified as \u3e30 km), and the likelihood of LDD was positively associated with the proportion of agricultural land cover around natal sites. Correlates of distance differed between LDD and SDD movements. LDD distance was positively correlated with latitude, a proxy for migration strategy, suggesting that migratory individuals disperse farther than residents. Distance of LDD in males was positively associated with maximum summer temperature. We did not find sex‐bias or an effect of population density in LDD distance or frequency. Within SDD, females tended to disperse farther than males, and distance was positively correlated with density. Sampling affected all responses, likely because local studies more frequently capture SDD within study areas. Our findings that LDD occurs at a relatively high frequency and is related to different proximate factors from SDD, including a lack of sex‐bias in LDD, suggest that LDD may be more common than previously reported, and LDD and SDD may be distinct processes rather than two outcomes originating from a single dispersal distribution. To our knowledge, this is the first evidence that LDD and SDD may be separate processes in an avian species, and suggests that environmental change may have different outcomes on the two processes
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