530 research outputs found
Influence of Fires, Fungi and Mountain Pine Beetles on Development of a Lodgepole Pine Forest in South-Central Oregon
Virtually pure lodgepole pine stands form an edaphic climax community over large areas of the infertile pumice plateau of south-central Oregon. During our ongoing studies on the dynamics of these forest we developed the scenario that periodic fires create fungal infection courts in damaged roots; in time, advanced decay develops in the butts and stems of these trees. The mountain pine beetle preferentially selects and kills these trees during the flight season. As these outbreaks develop, additional uninfected trees are attacked. In time, the stage is set for subsequent fires as needles drop, snags fall, and logs decay
Habitable Zones in the Universe
Habitability varies dramatically with location and time in the universe. This
was recognized centuries ago, but it was only in the last few decades that
astronomers began to systematize the study of habitability. The introduction of
the concept of the habitable zone was key to progress in this area. The
habitable zone concept was first applied to the space around a star, now called
the Circumstellar Habitable Zone. Recently, other, vastly broader, habitable
zones have been proposed. We review the historical development of the concept
of habitable zones and the present state of the research. We also suggest ways
to make progress on each of the habitable zones and to unify them into a single
concept encompassing the entire universe.Comment: 71 pages, 3 figures, 1 table; to be published in Origins of Life and
Evolution of Biospheres; table slightly revise
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Putting lives in danger? Tinker, tailor, journalist, spy: the use of journalistic cover
The Anglo-American intelligence agencies’ use of journalists as spies or propagandists and the practice of providing intelligence agents in the field with journalistic cover have been a source of controversy for many decades. This paper examines the extent to which these covert practices have taken place and whether they have put journalists’ lives in danger. This paper, drawing on various methodologies, examines a number of cases where the arrest, murder or kidnap of journalists was justified on the grounds that the journalist was a ‘spy’. This has been followed through with research using a range of sources that shows there have been many occasions when the distinction between spies and journalists has been opaque. The paper concludes that widespread use of journalistic cover by spies has put lives in danger but the extent is unquantifiable
Smoke consequences of new wildfire regimes driven by climate change
Smoke from wildfires has adverse biological and social consequences, and various lines of evidence suggest that smoke from wildfires in the future may be more intense and widespread, demanding that methods be developed to address its effects on people, ecosystems, and the atmosphere. In this paper, we present the essential ingredients of a modeling system for projecting smoke consequences in a rapidly warming climate that is expected to change wildfire regimes significantly. We describe each component of the system, offer suggestions for the elements of a modeling agenda, and provide some general guidelines for making choices among potential components. We address a prospective audience of researchers whom we expect to be fluent already in building some or many of these components, so we neither prescribe nor advocate particular models or software. Instead, our intent is to highlight fruitful ways of thinking about the task as a whole and its components, while providing substantial, if not exhaustive, documentation from the primary literature as reference. This paper provides a guide to the complexities of smoke modeling under climate change, and a research agenda for developing a modeling system that is equal to the task while being feasible with current resources
Researcher as Artist/Artist as Researcher
This is a postmodern article that is nontraditional in its form, content, and mode of representation. Upon recognizing that we share interests and common experiences as artists, we decided to collect life history information from each other about our artistic experiences. Thus we have become, simultaneously, "the researched" and "the re searcher." In these conversations, we explore the ways in which we were each guided by our past, very strong aesthetic and artistic experiences. We also include the voices of other researchers and artists in our conversations as we explore the influences of art in the formation of our worldviews.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68774/2/10.1177_107780049500100107.pd
Power grip, pinch grip, manual muscle testing or thenar atrophy - which should be assessed as a motor outcome after carpal tunnel decompression? A systematic review
<p>Abstract</p> <p>Background</p> <p>Objective assessment of motor function is frequently used to evaluate outcome after surgical treatment of carpal tunnel syndrome (CTS). However a range of outcome measures are used and there appears to be no consensus on which measure of motor function effectively captures change. The purpose of this systematic review was to identify the methods used to assess motor function in randomized controlled trials of surgical interventions for CTS. A secondary aim was to evaluate which instruments reflect clinical change and are psychometrically robust.</p> <p>Methods</p> <p>The bibliographic databases Medline, AMED and CINAHL were searched for randomized controlled trials of surgical interventions for CTS. Data on instruments used, methods of assessment and results of tests of motor function was extracted by two independent reviewers.</p> <p>Results</p> <p>Twenty-two studies were retrieved which included performance based assessments of motor function. Nineteen studies assessed power grip dynamometry, fourteen studies used both power and pinch grip dynamometry, eight used manual muscle testing and five assessed the presence or absence of thenar atrophy. Several studies used multiple tests of motor function. Two studies included both power and pinch strength and reported descriptive statistics enabling calculation of effect sizes to compare the relative responsiveness of grip and pinch strength within study samples. The study findings suggest that tip pinch is more responsive than lateral pinch or power grip up to 12 weeks following surgery for CTS.</p> <p>Conclusion</p> <p>Although used most frequently and known to be reliable, power and key pinch dynamometry are not the most valid or responsive tools for assessing motor outcome up to 12 weeks following surgery for CTS. Tip pinch dynamometry more specifically targets the thenar musculature and appears to be more responsive. Manual muscle testing, which in theory is most specific to the thenar musculature, may be more sensitive if assessed using a hand held dynamometer – the Rotterdam Intrinsic Handheld Myometer. However further research is needed to evaluate its reliability and responsiveness and establish the most efficient and psychometrically robust method of evaluating motor function following surgery for CTS.</p
Wildfire selectivity for land cover type: does size matter ?
Previous research has shown that fires burn certain land cover types disproportionally to their abundance. We used quantile
regression to study land cover proneness to fire as a function of fire size, under the hypothesis that they are inversely
related, for all land cover types. Using five years of fire perimeters, we estimated conditional quantile functions for lower
(avoidance) and upper (preference) quantiles of fire selectivity for five land cover types - annual crops, evergreen oak
woodlands, eucalypt forests, pine forests and shrublands. The slope of significant regression quantiles describes the rate of
change in fire selectivity (avoidance or preference) as a function of fire size. We used Monte-Carlo methods to randomly
permutate fires in order to obtain a distribution of fire selectivity due to chance. This distribution was used to test the null
hypotheses that 1) mean fire selectivity does not differ from that obtained by randomly relocating observed fire perimeters;
2) that land cover proneness to fire does not vary with fire size. Our results show that land cover proneness to fire is higher
for shrublands and pine forests than for annual crops and evergreen oak woodlands. As fire size increases, selectivity
decreases for all land cover types tested. Moreover, the rate of change in selectivity with fire size is higher for preference
than for avoidance. Comparison between observed and randomized data led us to reject both null hypotheses tested
(a = 0.05) and to conclude it is very unlikely the observed values of fire selectivity and change in selectivity with fire size are
due to chance.Funding: This paper was supported by the Fundação para a Ciência e Tecnologia Ph.D. Grant SFRH/BD/40398/2007. JMCP participated in this research under the
framework of research projects ‘‘Forest fire under climate, social and economic changes in Europe, the Mediterranean and other fire-affected areas of the world
(FUME)’’, EC FP7 Grant Agreement No. 243888. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the
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Tradeoffs and synergies in tropical forest root traits and dynamics for nutrient and water acquisition: Field and modeling advances
FUT6 deficiency compromises basophil function by selectively abrogating their sialyl-Lewis x expression
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