893 research outputs found
Emergence or improved detection of Japanese encephalitis virus in the Himalayan highlands?
The emergence of Japanese encephalitis virus (JEV) in the Himalayan highlands is of significant veterinary and public health concern and may be related to climate warming and anthropogenic landscape change, or simply improved surveillance. To investigate this phenomenon, a One Health approach focusing on the phylogeography of JEV, the distribution and abundance of the mosquito vectors, and seroprevalence in humans and animal reservoirs would be useful to understand the epidemiology of Japanese encephalitis in highland areas
Modeling the Potential Distribution of Bacillus anthracis under Multiple Climate Change Scenarios for Kazakhstan
Anthrax, caused by the bacterium Bacillus anthracis, is a zoonotic disease that persists throughout much of the world in livestock, wildlife, and secondarily infects humans. This is true across much of Central Asia, and particularly the Steppe region, including Kazakhstan. This study employed the Genetic Algorithm for Rule-set Prediction (GARP) to model the current and future geographic distribution of Bacillus anthracis in Kazakhstan based on the A2 and B2 IPCC SRES climate change scenarios using a 5-variable data set at 55 km2 and 8 km2 and a 6-variable BioClim data set at 8 km2. Future models suggest large areas predicted under current conditions may be reduced by 2050 with the A2 model predicting ∼14–16% loss across the three spatial resolutions. There was greater variability in the B2 models across scenarios predicting ∼15% loss at 55 km2, ∼34% loss at 8 km2, and ∼30% loss with the BioClim variables. Only very small areas of habitat expansion into new areas were predicted by either A2 or B2 in any models. Greater areas of habitat loss are predicted in the southern regions of Kazakhstan by A2 and B2 models, while moderate habitat loss is also predicted in the northern regions by either B2 model at 8 km2. Anthrax disease control relies mainly on livestock vaccination and proper carcass disposal, both of which require adequate surveillance. In many situations, including that of Kazakhstan, vaccine resources are limited, and understanding the geographic distribution of the organism, in tandem with current data on livestock population dynamics, can aid in properly allocating doses. While speculative, contemplating future changes in livestock distributions and B. anthracis spore promoting environments can be useful for establishing future surveillance priorities. This study may also have broader applications to global public health surveillance relating to other diseases in addition to B. anthracis
Hamilton's Turns for the Lorentz Group
Hamilton in the course of his studies on quaternions came up with an elegant
geometric picture for the group SU(2). In this picture the group elements are
represented by ``turns'', which are equivalence classes of directed great
circle arcs on the unit sphere , in such a manner that the rule for
composition of group elements takes the form of the familiar parallelogram law
for the Euclidean translation group. It is only recently that this construction
has been generalized to the simplest noncompact group , the double cover of SO(2,1). The present work develops a theory of
turns for , the double and universal cover of SO(3,1) and ,
rendering a geometric representation in the spirit of Hamilton available for
all low dimensional semisimple Lie groups of interest in physics. The geometric
construction is illustrated through application to polar decomposition, and to
the composition of Lorentz boosts and the resulting Wigner or Thomas rotation.Comment: 13 pages, Late
Complex-Distance Potential Theory and Hyperbolic Equations
An extension of potential theory in R^n is obtained by continuing the
Euclidean distance function holomorphically to C^n. The resulting Newtonian
potential is generated by an extended source distribution D(z) in C^n whose
restriction to R^n is the delta function. This provides a natural model for
extended particles in physics. In C^n, interpreted as complex spacetime, D(z)
acts as a propagator generating solutions of the wave equation from their
initial values. This gives a new connection between elliptic and hyperbolic
equations that does not assume analyticity of the Cauchy data. Generalized to
Clifford analysis, it induces a similar connection between solutions of
elliptic and hyperbolic Dirac equations. There is a natural application to the
time-dependent, inhomogeneous Dirac and Maxwell equations, and the
`electromagnetic wavelets' introduced previously are an example.Comment: 25 pages, submited to Proceedings of 5th Intern. Conf. on Clifford
Algebras, Ixtapa, June 24 - July 4, 199
Revisiting special relativity: A natural algebraic alternative to Minkowski spacetime
Minkowski famously introduced the concept of a space-time continuum in 1908,
merging the three dimensions of space with an imaginary time dimension , with the unit imaginary producing the correct spacetime distance , and the results of Einstein's then recently developed theory of special
relativity, thus providing an explanation for Einstein's theory in terms of the
structure of space and time. As an alternative to a planar Minkowski space-time
of two space dimensions and one time dimension, we replace the unit imaginary , with the Clifford bivector for the plane
that also squares to minus one, but which can be included without the addition
of an extra dimension, as it is an integral part of the real Cartesian plane
with the orthonormal basis and . We find that with this model of
planar spacetime, using a two-dimensional Clifford multivector, the spacetime
metric and the Lorentz transformations follow immediately as properties of the
algebra. This also leads to momentum and energy being represented as components
of a multivector and we give a new efficient derivation of Compton's scattering
formula, and a simple formulation of Dirac's and Maxwell's equations. Based on
the mathematical structure of the multivector, we produce a semi-classical
model of massive particles, which can then be viewed as the origin of the
Minkowski spacetime structure and thus a deeper explanation for relativistic
effects. We also find a new perspective on the nature of time, which is now
given a precise mathematical definition as the bivector of the plane.Comment: 29 pages, 2 figure
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International Assistance After Conflict: Health, Transitional Justice, and Opportunity Costs
After violent conflicts, international actors face difficult choices about whether and how to provide assistance. These decisions can have immense consequences. As aid always occurs under conditions of scarcity, theoretical reflection is crucial to reveal the opportunity costs and potential tensions between alternative courses of action. Yet, there has been relatively little scholarly reflection on what should constitute priorities for post-conflict assistance and why. This paper advances this debate by comparing two very different areas of assistance that both embody compelling values and goals: public health and transitional justice. It argues that aid for public health deserves greater attention based on powerful normative considerations and its impressive empirical record. It also suggests the need to examine not only clearly underperforming areas, but also tough cases. Transitional justice, despite its strong normative foundations, faces challenges and limitations that justify reform and a reconsideration of the emphasis commonly placed on it. Our intention is not to suggest that long-standing commitments ought to be abandoned or that all aid should be allocated to health. Rather, by scrutinizing the priorities of international assistance, we hope to start a general discussion about how the international community can best help societies heal after conflict
Site adaptations of Acanthogyrus (Acanthosentis) tilapiae: Observations through light and scanning electron microscopy
Acanthogyrus (Acanthosentis) tilapiae parasites were collected from the intestines of 300 fish belonging to three tilapia species sourced at the River Nile, Giza, Egypt. The proboscis of the parasite was characterized by three rows of hooks that curved towards the posterior of the body. The first row is supported by unmodified hooks. The parasite tegument has a series of alternative folds and a large number of pores. Sensory ganglia are located on the surface of the proboscis and body. Acanthogyrus (Acanthosentis) tilapiae provokes an aggressive host response indicated by hyperplasia of the intestinal goblet cells and focal eosinophil infiltrations. This acanthocephalan parasite shows a highly modified adaptation to its site of host infection
A bovine lymphosarcoma cell line infected with theileria annulata exhibits an irreversible reconfiguration of host cell gene expression
Theileria annulata, an intracellular parasite of bovine lymphoid cells, induces substantial phenotypic alterations to its host cell including continuous proliferation, cytoskeletal changes and resistance to apoptosis. While parasite induced modulation of host cell signal transduction pathways and NFκB activation are established, there remains considerable speculation on the complexities of the parasite directed control mechanisms that govern these radical changes to the host cell. Our objectives in this study were to provide a comprehensive analysis of the global changes to host cell gene expression with emphasis on those that result from direct intervention by the parasite. By using comparative microarray analysis of an uninfected bovine cell line and its Theileria infected counterpart, in conjunction with use of the specific parasitacidal agent, buparvaquone, we have identified a large number of host cell gene expression changes that result from parasite infection. Our results indicate that the viable parasite can irreversibly modify the transformed phenotype of a bovine cell line. Fifty percent of genes with altered expression failed to show a reversible response to parasite death, a possible contributing factor to initiation of host cell apoptosis. The genes that did show an early predicted response to loss of parasite viability highlighted a sub-group of genes that are likely to be under direct control by parasite infection. Network and pathway analysis demonstrated that this sub-group is significantly enriched for genes involved in regulation of chromatin modification and gene expression. The results provide evidence that the Theileria parasite has the regulatory capacity to generate widespread change to host cell gene expression in a complex and largely irreversible manner
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