637 research outputs found
Biochemical and haematological values in abattoir pigs with and without subclinical lesions
The biochemical and haematological profiles of 379 pigs with or without various gross pathological lesions in an abattoir in Zimbabwe were studied to see whether there were any differences between the levels of haematological and biochemical values, and health status (with and without pathological lesions). On the basis of observable gross pathology, 134 pigs were classified as having one or more subclinical lesions (liver milk spot, pneumonia, pleurisy, pericarditis, abscesses and arthritis). Seventy six of these were males and 58 females. There were observable sex differences in the mean haematological and biochemical values obtained. Erythrocyte counts showed significant differences in mean values (P < 0,05) among groups of pigs found with various pathological lesions. The biochemical values showed significant group differences for ALP, ALT. AST, and LDH.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi.
Adobe Acrobat X Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.University of Zimbabwe Research Boardmn201
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Long-term changes to the frequency of occurrence of British moths are consistent with opposing and synergistic effects of climate and land-use changes
1. Speciesâ distributions are likely to be affected by a combination of environmental drivers. We used a data set of 11 million species occurrence records over the period 1970â2010 to assess changes in the frequency of occurrence of 673 macro-moth species in Great Britain. Groups of species with different predicted sensitivities showed divergent trends, which we interpret in the context of land-use and climatic changes.
2. A diversity of responses was revealed: 260 moth species declined significantly, whereas 160 increased significantly. Overall, frequencies of occurrence declined, mirroring trends in less species-rich, yet more intensively studied taxa.
3. Geographically widespread species, which were predicted to be more sensitive to land use than to climate change, declined significantly in southern Britain, where the cover of urban and arable land has increased.
4. Moths associated with low nitrogen and open environments (based on their larval host plant characteristics) declined most strongly, which is also consistent with a land-use change explanation.
5. Some moths that reach their northern (leading edge) range limit in southern Britain increased, whereas species restricted to northern Britain (trailing edge) declined significantly, consistent with a climate change explanation.
6. Not all species of a given type behaved similarly, suggesting that complex interactions between speciesâ attributes and different combinations of environmental drivers determine frequency of occurrence changes.
7. Synthesis and applications. Our findings are consistent with large-scale responses to climatic and land-use changes, with some species increasing and others decreasing. We suggest that land-use change (e.g. habitat loss, nitrogen deposition) and climate change are both major drivers of moth biodiversity change, acting independently and in combination. Importantly, the diverse responses revealed in this species-rich taxon show that multifaceted conservation strategies are needed to minimize negative biodiversity impacts of multiple environmental changes. We suggest that habitat protection, management and ecological restoration can mitigate combined impacts of land-use change and climate change by providing environments that are suitable for existing populations and also enable species to shift their ranges
Seashore disturbance and management of the clonal Arctophila fulva : Modelling patch dynamics
Question: What is the population viability of a critically
endangered seashore grass, Arctophila fulva var. pendulina.
Location: Liminka Bay, W Finland, 25°21'70 N, 64°51'90 E.
Methods: We constructed a matrix population model based
on colonization and disappearance events and patch size
changes of A. fulva. Patches were divided into hydric and nonhydric
zones according to proximity to the seashore and intensity
of disturbance. Perturbation analyses were carried out in
order to identify transitions critical for population growth.
Seed bank and seed germination studies provided background
information for the model design.
Results: A. fulva patches observed in the more disturbed
hydric zone (closest to the sea) increased in number, as did the
total number of patches. However, the number of patches in
the less disturbed non-hydric zone decreased.
Conclusions: Short-term dynamics of the A. fulva population
at Liminka Bay seem to be determined by environmental
fluctuations, which cause annual variation in transition rates
between patch size classes. The long-term dynamics are probably
governed by initiation of primary succession by isostatic
land uplift. Increased disturbance at the waterâs edge may
promote persistence of A. fulva through reduced interspecific
competition. Our results suggest that shoreline disturbance of
the hydric zone is sufficient for maintaining a viable population.
Competitive exclusion of A. fulva in the non-hydric zone
may be delayed by management practices, such as mowing
Entanglement in bipartite generalized coherent states
Entanglement in a class of bipartite generalized coherent states is
discussed. It is shown that a positive parameter can be associated with the
bipartite generalized coherent states so that the states with equal value for
the parameter are of equal entanglement. It is shown that the maximum possible
entanglement of 1 bit is attained if the positive parameter equals .
The result that the entanglement is one bit when the relative phase between the
composing states is in bipartite coherent states is shown to be true for
the class of bipartite generalized coherent states considered.Comment: 10 pages, 4 figures; typos corrected and figures redrawn for better
clarit
Bayesian classification of vegetation types with Gaussian mixture density fitting to indicator values.
Question: Is it possible to mathematically classify relevés into vegetation types on the basis of their average indicator values, including the uncertainty of the classification? Location: The Netherlands. Method: A large relevé database was used to develop a method for predicting vegetation types based on indicator values. First, each relevé was classified into a phytosociological association on the basis of its species composition. Additionally, mean indicator values for moisture, nutrients and acidity were computed for each relevé. Thus, the position of each classified relevé was obtained in a three-dimensional space of indicator values. Fitting the data to so called Gaussian Mixture Models yielded densities of associations as a function of indicator values. Finally, these density functions were used to predict the Bayesian occurrence probabilities of associations for known indicator values. Validation of predictions was performed by using a randomly chosen half of the database for the calibration of densities and the other half for the validation of predicted associations. Results and Conclusions: With indicator values, most relevés were classified correctly into vegetation types at the association level. This was shown using confusion matrices that relate (1) the number of relevés classified into associations based on species composition to (2) those based on indicator values. Misclassified relevés belonged to ecologically similar associations. The method seems very suitable for predictive vegetation models
Force and Motion Generation of Molecular Motors: A Generic Description
We review the properties of biological motor proteins which move along linear
filaments that are polar and periodic. The physics of the operation of such
motors can be described by simple stochastic models which are coupled to a
chemical reaction. We analyze the essential features of force and motion
generation and discuss the general properties of single motors in the framework
of two-state models. Systems which contain large numbers of motors such as
muscles and flagella motivate the study of many interacting motors within the
framework of simple models. In this case, collective effects can lead to new
types of behaviors such as dynamic instabilities of the steady states and
oscillatory motion.Comment: 29 pages, 9 figure
Generation of atom-photon entangled states in atomic Bose-Einstein condensate via electromagnetically induced transparency
In this paper, we present a method to generate continuous-variable-type
entangled states between photons and atoms in atomic Bose-Einstein condensate
(BEC). The proposed method involves an atomic BEC with three internal states, a
weak quantized probe laser and a strong classical coupling laser, which form a
three-level Lambda-shaped BEC system. We consider a situation where the BEC is
in electromagnetically induced transparency (EIT) with the coupling laser being
much stronger than the probe laser. In this case, the upper and intermediate
levels are unpopulated, so that their adiabatic elimination enables an
effective two-mode model involving only the atomic field at the lowest internal
level and the quantized probe laser field. Atom-photon quantum entanglement is
created through laser-atom and inter-atomic interactions, and two-photon
detuning. We show how to generate atom-photon entangled coherent states and
entangled states between photon (atom) coherent states and atom-(photon-)
macroscopic quantum superposition (MQS) states, and between photon-MQS and
atom-MQS states.Comment: 9 pages, 1 figur
Multiorder coherent Raman scattering of a quantum probe field
We study the multiorder coherent Raman scattering of a quantum probe field in
a far-off-resonance medium with a prepared coherence. Under the conditions of
negligible dispersion and limited bandwidth, we derive a Bessel-function
solution for the sideband field operators. We analytically and numerically
calculate various quantum statistical characteristics of the sideband fields.
We show that the multiorder coherent Raman process can replicate the
statistical properties of a single-mode quantum probe field into a broad comb
of generated Raman sidebands. We also study the mixing and modulation of photon
statistical properties in the case of two-mode input. We show that the prepared
Raman coherence and the medium length can be used as control parameters to
switch a sideband field from one type of photon statistics to another type, or
from a non-squeezed state to a squeezed state and vice versa.Comment: 12 pages, 7 figures, to be published in Phys. Rev.
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