259 research outputs found
Entropic Tightening of Vibrated Chains
We investigate experimentally the distribution of configurations of a ring
with an elementary topological constraint, a ``figure-8'' twist. Using vibrated
granular chains, which permit controlled preparation and direct observation of
such a constraint, we show that configurations where one of the loops is tight
and the second is large are strongly preferred. This agrees with recent
predictions for equilibrium properties of topologically-constrained polymers.
However, the dynamics of the tightening process weakly violate detailed
balance, a signature of the nonequilibrium nature of this system.Comment: 4 pages, 4 figure
Invasive potential of cattle fever ticks in the southern United States
Background
For >100 years cattle production in the southern United States has been threatened by cattle fever. It is caused by an invasive parasite-vector complex that includes the protozoan hemoparasites Babesia bovis and B. bigemina, which are transmitted among domestic cattle via Rhipicephalus tick vectors of the subgenus Boophilus. In 1906 an eradication effort was started and by 1943 Boophilus ticks had been confined to a narrow tick eradication quarantine area (TEQA) along the Texas-Mexico border. However, a dramatic increase in tick infestations in areas outside the TEQA over the last decade suggests these tick vectors may be poised to re-invade the southern United States. We investigated historical and potential future distributions of climatic habitats of cattle fever ticks to assess the potential for a range expansion.
Methods
We built robust spatial predictions of habitat suitability for the vector species Rhipicephalus (Boophilus) microplus and R. (B.) annulatus across the southern United States for three time periods: 1906, present day (2012), and 2050. We used analysis of molecular variance (AMOVA) to identify persistent tick occurrences and analysis of bias in the climate proximate to these occurrences to identify key environmental parameters associated with the ecology of both species. We then used ecological niche modeling algorithms GARP and Maxent to construct models that related known occurrences of ticks in the TEQA during 2001–2011 with geospatial data layers that summarized important climate parameters at all three time periods.
Results
We identified persistent tick infestations and specific climate parameters that appear to be drivers of ecological niches of the two tick species. Spatial models projected onto climate data representative of climate in 1906 reproduced historical pre-eradication tick distributions. Present-day predictions, although constrained to areas near the TEQA, extrapolated well onto climate projections for 2050.
Conclusions
Our models indicate the potential for range expansion of climate suitable for survival of R. microplus and R. annulatus in the southern United States by mid-century, which increases the risk of reintroduction of these ticks and cattle tick fever into major cattle producing areas.We thank USDA-APHIS mounted patrol inspectors for collecting field samples used in this study. This work was supported by USDA-NIFA Grant 2010-65104-20386. Use of trade, product, or firm names does not imply endorsement by the US Government. The USDA is an equal opportunity provider and employer
Cloning and structure-function analysis of the Leishmania donovani kinetoplastid membrane protein-11
Heidegger’s Underdeveloped Conception of the Undistinguishedness (Indifferenz) of Everyday Human Existence
This chapter provides an interpretation of the early Heidegger’s underdeveloped conception of the undistinguishedness of everyday human existence in Being and Time. After explaining why certain translation choices of some key terms in this text are interpretively and philosophically important, I first provide a concise argument for why the social constitution interpretation of the relation between ownedness and unownedness makes better overall sense of Heidegger’s ambivalent attitude toward the social constitution of the human being than the standard existentialist interpretation of this relation. I then proceed to the heart of this chapter, which develops his inchoate conception of the undistinguishedness of everydayness by arguing that it specifies the third distinctive mode of concrete human existence in addition to ownedness and unownedness. Accordingly, I show how unownedness is actually a generic phenomenon with two distinct species, namely, undistinguishedness and disownedness, which are at once closely related to, but also differ in significant respects from, each other. Consequently, instead of taking for granted a one-dimensional and mutually exclusive opposition between ‘authenticity’ and ‘inauthenticity’, I argue that we should adopt a two-dimensional and more nuanced understanding of the relations among undistinguishedness, disownedness, and ownedness that intersects with Heidegger’s underappreciated distinction between genuineness and ungenuineness. After raising and replying to some objections to this interpretation of undistinguishedness, I conclude this chapter by briefly sketching three of its philosophical consequences and pointing out its potential as an important resource for contemporary social theories
Widespread movement of invasive cattle fever ticks (Rhipicephalus microplus) in southern Texas leads to shared local infestations on cattle and deer
Background: Rhipicephalus (Boophilus) microplus is a highly-invasive tick that transmits the cattle parasites (Babesia bovis and B. bigemina) that cause cattle fever. R. microplus and Babesia are endemic in Mexico and ticks persist in the United States inside a narrow tick eradication quarantine area (TEQA) along the Rio Grande. This containment area is threatened by unregulated movements of illegal cattle and wildlife like white-tailed deer (WTD; Odocoileus virginianus). Methods: Using 11 microsatellite loci we genotyped 1,247 R. microplus from 63 Texas collections, including outbreak infestations from outside the TEQA. We used population genetic analyses to test hypotheses about ecological persistence, tick movement, and impacts of the eradication program in southern Texas. We tested acaricide resistance with larval packet tests (LPTs) on 47 collections. Results: LPTs revealed acaricide resistance in 15/47 collections (32%); 11 were outside the TEQA and three were resistant to multiple acaricides. Some collections highly resistant to permethrin were found on cattle and WTD. Analysis of genetic differentiation over time at seven properties revealed local gene pools with very low levels of differentiation (F-ST 0.00-0.05), indicating persistence over timespans of up to 29 months. However, in one neighborhood differentiation varied greatly over a 12-month period (F-ST 0.03-0.13), suggesting recurring immigration from distinct sources as another persistence mechanism. Ticks collected from cattle and WTD at the same location are not differentiated (F-ST = 0), implicating ticks from WTD as a source of ticks on cattle (and vice versa) and emphasizing the importance of WTD to tick control strategies. We identified four major genetic groups (K = 4) using Bayesian population assignment, suggesting multiple introductions to Texas. Conclusions: Two dispersal mechanisms give rise to new tick infestations: 1) frequent short-distance dispersal from the TEQA; and 2) rare long-distance, human-mediated dispersal from populations outside our study area, probably Mexico. The threat of cattle fever tick transport into Texas is increased by acaricide resistance and the ability of R. microplus to utilize WTD as an alternate host. Population genetic analyses may provide a powerful tool for tracking invasions in other parts of the world where these ticks are established
Book reviews
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45784/1/11153_2004_Article_BF00140614.pd
‘You do it in your own particular way.’ Physical education, gender and (dis)ability
Ready, steady, learn: school readiness and children’s voices in English early childhood settings
Internationally, school readiness is increasingly the rationale for early childhood education and care. This is the case in England, yet the statutory English Early Years Foundation Stage framework for children 0-5 years also requires practitioners to listen to children’s voices: discourse indicates dissonance between school readiness and listening to children’s voices so this paper discusses an intrinsic case study that investigated beliefs and practices of 25 practitioners in the English midlands regarding school readiness and listening to children’s voices. In survey responses and semi-structured interviews, practitioners indicated they listen to – and act on – children’s voices but are confused about school readiness; their beliefs and practices align more strongly with social pedagogy than pre-primary schoolification. Findings carry messages for policymakers regarding the need for coherent policy concerning the purpose of early childhood education and care, with practitioner training and a framework aligned fully with that policy. A larger study is indicated
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