1,017 research outputs found
Integrated control of vector-borne diseases of livestock--pyrethroids: panacea or poison?
Tick- and tsetse-borne diseases cost Africa approximately US$4-5 billion per year in livestock production-associated losses. The use of pyrethroid-treated cattle to control ticks and tsetse promises to be an increasingly important tool to counter this loss. However, uncontrolled use of this technology might lead to environmental damage, acaricide resistance in tick populations and a possible exacerbation of tick-borne diseases. Recent research to identify, quantify and to develop strategies to avoid these effects are highlighted
Tai Chi and Stress Reduction in Premedical Students
A randomized, controlled pilot study was performed to determine the correlation between the practice of Tai Chi exercise and anxiety scores, among full-time pre-med undergraduate students who reside in college campus housing. The sample (N = 14) was recruited from 70 pre-med students enrolled at Lake Erie College (LEC) located in Painesville, Ohio. Participants included: (a) full-time LEC pre-med students; (b) between 18 and 25 years old; and (c) residents of either on-campus housing or within two miles of the college campus. Participants were randomly assigned to one of two groups: (a) Tai Chi (n = 8); (b) control (n = 6). The Tai Chi group received instruction from a certified instructor, three times a week for five weeks. The control group received no training. Both groups completed a basic health history questionnaire including blood pressure and pulse measurements, maintained a physical activity log, and completed a pre and post measure of anxiety using the Beck Anxiety Inventory (BAI)© scale. The p-value of .334 between pre-study control and Tai Chi groups was greater than the alpha level at 0.05. The p-value of .101 between post-study control and Tai Chi groups was greater than the alpha level at 0.05. The small sample size of this pilot limited the generalizability of this study. Therefore, there was insufficient evidence to conclude that the true mean anxiety change between the pre-test and post-test in pre-med students taking Tai Chi was greater than the true mean anxiety change between the pre-test and post-test in pre-med students maintaining normal daily activities. However, this was a small pilot study, and research suggests the anxiety lowering effects of Tai Chi, therefore this research will be expanded for a multi-center study.https://fuse.franklin.edu/ss2014/1040/thumbnail.jp
S-Wave Scattering of Charged Fermions by a Magnetic Black Hole
We argue that, classically, -wave electrons incident on a magnetically
charged black hole are swallowed with probability one: the reflection
coefficient vanishes. However, quantum effects can lead to both electromagnetic
and gravitational backscattering. We show that, for the case of extremal,
magnetically charged, dilatonic black holes and a single flavor of low-energy
charged particles, this backscattering is described by a perturbatively
computable and unitary -matrix, and that the Hawking radiation in these
modes is suppressed near extremality. The interesting and much more difficult
case of several flavors is also discussed.Comment: 9p
Quantum Field Theory of Nonabelian Strings and Vortices
We develop an operator formalism for investigating the properties of
nonabelian cosmic strings (and vortices) in quantum field theory. Operators are
constructed that introduce classical string sources and that create dynamical
string loops. The operator construction in lattice gauge theory is explicitly
described, and correlation functions are computed in the strong--coupling and
weak--coupling limits. These correlation functions are used to study the
long--range interactions of nonabelian strings, taking account of
charge--screening effects due to virtual particles. Among the phenomena
investigated are the Aharonov--Bohm interactions of strings with charged
particles, holonomy interactions between string loops, string entanglement, the
transfer of ``Cheshire charge'' to a string loop, and domain wall decay via
spontaneous string nucleation. We also analyze the Aharonov--Bohm interactions
of magnetic monopoles with electric flux tubes in a confining gauge theory. We
propose that the Aharonov--Bohm effect can be invoked to distinguish among
various phases of a nonabelian gauge theory coupled to matter.Comment: (82 pp
Virus transcript levels and cell growth rates after naturally occurring HPV16 integration events in basal cervical keratinocytes.
Cervical carcinogenesis is characterized by a clonal selection process in which the high-risk human papillomavirus (HRHPV) genome usually changes from the extra-chromosomal (episomal) state seen in productive infections to DNA that is integrated into host chromosomes. However, it is not clear whether all HRHPV integration events provide cells with a selective growth advantage compared with the episome-containing cells from which they originate. It is also unclear whether selection of cells containing a particular integrant from a mixed population simply reflects the highest levels of virus oncogene expression or has additional determinants. These early events in cervical carcinogenesis cannot readily be addressed by cross-sectional studies of clinical samples. We used the W12 model system to generate a panel of cervical squamous cell clones that were derived from an identical background under non-competitive conditions and differed only by the genomic site of HPV16 integration. Compared with the 'baseline' episome-containing cells from which they were isolated, only 9/17 clones (53%) showed significantly greater growth rates and only 7/17 (41%) showed significantly greater expression of the major virus oncogenes E7/E6. There were significant variations in levels of HPV16 transcription per DNA template, changes that were associated with histone modifications in the integrated virus chromatin. Cell growth rates showed only weak and non-significant associations with protein and mRNA levels for E7, E6, and the mean E7/E6 values. We conclude that HPV16 integration in basal cervical cells does not necessarily lead to increased levels of virus oncogenes, or to a competitive growth advantage, when compared with the initiating episome-containing cells
Controlling malaria using livestock-based interventions: a one health approach.
Where malaria is transmitted by zoophilic vectors, two types of malaria control strategies have been proposed based on animals: using livestock to divert vector biting from people (zooprophylaxis) or as baits to attract vectors to insecticide sources (insecticide-treated livestock). Opposing findings have been obtained on malaria zooprophylaxis, and despite the success of an insecticide-treated livestock trial in Pakistan, where malaria vectors are highly zoophilic, its effectiveness is yet to be formally tested in Africa where vectors are more anthropophilic. This study aims to clarify the different effects of livestock on malaria and to understand under what circumstances livestock-based interventions could play a role in malaria control programmes. This was explored by developing a mathematical model and combining it with data from Pakistan and Ethiopia. Consistent with previous work, a zooprophylactic effect of untreated livestock is predicted in two situations: if vector population density does not increase with livestock introduction, or if livestock numbers and availability to vectors are sufficiently high such that the increase in vector density is counteracted by the diversion of bites from humans to animals. Although, as expected, insecticide-treatment of livestock is predicted to be more beneficial in settings with highly zoophilic vectors, like South Asia, we find that the intervention could also considerably decrease malaria transmission in regions with more anthropophilic vectors, like Anopheles arabiensis in Africa, under specific circumstances: high treatment coverage of the livestock population, using a product with stronger or longer lasting insecticidal effect than in the Pakistan trial, and with small (ideally null) repellency effect, or if increasing the attractiveness of treated livestock to malaria vectors. The results suggest these are the most appropriate conditions for field testing insecticide-treated livestock in an Africa region with moderately zoophilic vectors, where this intervention could contribute to the integrated control of malaria and livestock diseases
Black Holes with a Generalized Gravitational Action
Microscopic black holes are sensitive to higher dimension operators in the
gravitational action. We compute the influence of these operators on the
Schwarzschild solution using perturbation theory. All (time reversal invariant)
operators of dimension six are included (dimension four operators don't alter
the Schwarzschild solution). Corrections to the relation between the Hawking
temperature and the black hole mass are found. The entropy is calculated using
the Gibbons-Hawking prescription for the Euclidean path integral and using
naive thermodynamic reasoning. These two methods agree, however, the entropy is
not equal to 1/4 the area of the horizon.Comment: plain tex(uses phyzzx.tex), 8 pages, CALT-68-185
A Quantum Mechanical Model of Spherical Supermembranes
We present a quantum mechanical model of spherical supermembranes. Using
superfields to represent the cartesian coordinates of the membrane, we are able
to exactly determine its supersymmetric vacua. We find there are two classical
vacua, one corresponding to an extended membrane and one corresponding to a
point-like membrane. For the case, instanton effects then
lift these vacua to massive states. For the case, there is
no instanton tunneling, and the vacua remain massless. Similarities to
spherical supermembranes as giant gravitons and in Matrix theory on pp-waves is
discussed.Comment: 9 page
The structure of the G protein heterotrimer Giα1ÎČ1Îł2
AbstractThe crystallographic structure of the G protein heterotrimer Giα1(GDP)ÎČ1Îł2 (at 2.3 A) reveals two nonoverlapping regions of contact between α and ÎČ, an extended interface between ÎČ and nearly all of Îł, and limited interaction of α with Îł. The major α/ÎČ interface covers switch II of α, and GTP-induced rearrangement of switch II causes subunit dissociation during signaling. Alterations in GDP binding in the heterotrimer (compared with α-GDP) explain stabilization of the inactive conformation of α by ÎČÎł. Repeated WD motifs in ÎČ form a circularized sevenfold ÎČ propeller. The conserved cores of these motifs are a scaffold for display of their more variable linkers on the exterior face of each propeller blade
Simulated Annealing for Topological Solitons
The search for solutions of field theories allowing for topological solitons
requires that we find the field configuration with the lowest energy in a given
sector of topological charge. The standard approach is based on the numerical
solution of the static Euler-Lagrange differential equation following from the
field energy. As an alternative, we propose to use a simulated annealing
algorithm to minimize the energy functional directly. We have applied simulated
annealing to several nonlinear classical field theories: the sine-Gordon model
in one dimension, the baby Skyrme model in two dimensions and the nuclear
Skyrme model in three dimensions. We describe in detail the implementation of
the simulated annealing algorithm, present our results and get independent
confirmation of the studies which have used standard minimization techniques.Comment: 31 pages, LaTeX, better quality pics at
http://www.phy.umist.ac.uk/~weidig/Simulated_Annealing/, updated for
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