670 research outputs found
Movement of pathogens between horticultural crops and endemic trees in the Kimberleys
Recently a survey of endophytes associated with boabs (Adansonia gregorrii) and associated tree species in the Kimberleys, Western Australia has resulted in the description of seven new species in the Botryosphaeriaceae (Pavlic et al. 2008). Additionally several common species of Lasiodiplodia, (L. theobromae, L. pseudoptheobromae and L. parva) were also isolated as endophytes of endemic tree species.
Concurrently, surveys in the Ord River Irrigation Area (ORIA) have revealed Mangiferum indica trees showing symptoms of dieback and cankers. In this project we isolated, identified and determined the pathogenicity of fungi associated with these cankers
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Ubiquitous Internet in an integrated satellite-terrestrial environment: The SUITED solution
yesThe current Internet architecture appears to
not be particularly suited to addressing the
emerging needs of new classes of users who wish
to gain access to multimedia services made available
by ISPs, regardless of their location, while
in motion and with a guaranteed level of quality.
One of the main objectives of so-called nextgeneration
systems is to overcome the limitations
of todayÂżs available Internet by adopting an
approach based on the integration of different
mobile and fixed networks. The SUITED project
moves in this direction since it aims at contributing
to the design and deployment of the global
mobile broadband system (GMBS), a unique
satellite/terrestrial infrastructure ensuring
nomadic users access to Internet services with a
negotiated QoS. A description of the main features
of the GMBS architecture, characterized
by the integration of a multisegment access network
with a federated ISP network is given in
this article. The GMBS multimode terminal is
schematically described, and an overview of the
so-called QoS-aware mobility management
scheme, devised for such a heterogeneous scenario,is provided
Clinical audit of malaria diagnosis in urban primary curative care clinics, Zimbabwe
A CAJM journal article.Clinical audit was performed on the accuracy of malaria diagnosis by nursing staff within Harare City Health Department using diagnosis by doctors as the reference standard. This was found to be about 10 pc based on symptoms. The criteria for diagnosis of malaria as in ZEDAP manuals and in-house training were not being utilised. Pyrexia was not present in 40 pc of the patients. Serious illnesses were occasionally dismissed as malaria and not treated appropriately or reviewed. The most common misdiagnosis was of acute respiratory tract infections which also have clear guidelines for diagnosis.
More appropriate training methods need to be developed to improve the diagnostic capacity of nursing staff who are front line providers of primary health care. This study shows the importance of performing an audit for process evaluation, compared to set standards and to be used for improving the quality of services
Amplitude and phase representation of quantum invariants for the time dependent harmonic oscillator
The correspondence between classical and quantum invariants is established.
The Ermakov Lewis quantum invariant of the time dependent harmonic oscillator
is translated from the coordinate and momentum operators into amplitude and
phase operators. In doing so, Turski's phase operator as well as
Susskind-Glogower operators are generalized to the time dependent harmonic
oscillator case. A quantum derivation of the Manley-Rowe relations is shown as
an example
SatNEx: A Network of Excellence Providing Training in Satellite Communications
YesSatellite communications represents a specialised area of telecommunications. While the development of satellite technology is relatively slow in comparison to wireless networks evolution, due to the need for high reliability, the services that satellites are able to offer are evolving at much the same pace as their terrestrial counterparts. It is within this context that the satellite communications network of excellence (SatNEx) has evolved its initiative, the aim being to serve the engineering community with the latest technological trends, while also providing a solid grounding in the fundamentals for those new to the subject area.European Commission Framework Programme
Processing of ultrafine-size particulate metal matrix composites by advanced shear technology
Copyright @ 2009 ASM International. This paper was published in Metallurgical & Materials Transactions A 40A(3) and is made available as an electronic reprint with the permission of ASM International. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplications of any material in this paper for a fee or for commercial purposes, or modification of the content of this paper are prohibited.Lack of efficient mixing technology to achieve a uniform distribution of fine-size reinforcement within the matrix and the high cost of producing components have hindered the widespread adaptation of particulate metal matrix composites (PMMCs) for engineering applications. A new rheo-processing method, the melt-conditioning high-pressure die-cast (MC-HPDC) process, has been developed for manufacturing near-net-shape components of high integrity. The MC-HPDC process adapts the well-established high shear dispersive mixing action of a twin-screw mechanism to the task of overcoming the cohesive force of the agglomerates under a high shear rate and high intensity of turbulence. This is followed by direct shaping of the slurry into near-net-shape components using an existing cold-chamber die-casting process. The results indicate that the MC-HPDC samples have a uniform distribution of ultrafine-sized SiC particles throughout the entire sample in the as-cast condition. Compared to those produced by conventional high-pressure die casting (HPDC), MC-HPDC samples have a much improved tensile strength and ductility.EP-SR
Designing Functionally Selective Noncatechol Dopamine D1 Receptor Agonists with Potent in Vivo Antiparkinsonian Activity
Dopamine receptors are important G protein-coupled receptors (GPCRs) with therapeutic opportunities for treating Parkinson's Disease (PD) motor and cognitive deficits. Biased D1 dopamine ligands that differentially activate G protein over β-arrestin recruitment pathways are valuable chemical tools for dissecting positive versus negative effects in drugs for PD. Here, we reveal an iterative approach toward modification of a D1-selective noncatechol scaffold critical for G protein-biased agonism. This approach provided enhanced understanding of the structural components critical for activity and signaling bias and led to the discovery of several novel compounds with useful pharmacological properties, including three highly GS-biased partial agonists. Administration of a potent, balanced, and brain-penetrant lead compound from this series results in robust antiparkinsonian effects in a rodent model of PD. This study suggests that the noncatechol ligands developed through this approach are valuable tools for probing D1 receptor signaling biology and biased agonism in models of neurologic disease
Defining Structure-Functional Selectivity Relationships (SFSR) for a Class of Non-Catechol Dopamine D1 Receptor Agonists
G protein-coupled receptors (GPCRs) are capable of downstream signaling through distinct noncanonical pathways such as β-arrestins in addition to the canonical G protein-dependent pathways. GPCR ligands that differentially activate the downstream signaling pathways are termed functionally selective or biased ligands. A class of novel non-catechol G protein-biased agonists of the dopamine D1 receptor (D1R) was recently disclosed. We conducted the first comprehensive structure-functional selectivity relationship study measuring GS and β-arrestin2 recruitment activities focused on four regions of this scaffold, resulting in over 50 analogs with diverse functional selectivity profiles. Some compounds became potent full agonists of β-arrestin2 recruitment, while others displayed enhanced GS bias compared to the starting compound. Pharmacokinetic testing of an analog with an altered functional selectivity profile demonstrated excellent blood-brain barrier penetration. This study provides novel tools for studying ligand bias at D1R and paves the way for developing the next generation of biased D1R ligands. Copyright © 2019 American Chemical Society
Eco-evolutionary dynamics on deformable fitness landscapes
Conventional approaches to modelling ecological dynamics often do not include evolutionary changes in the genetic makeup of component species and, conversely, conventional approaches to modelling evolutionary changes in the genetic makeup of a population often do not include ecological dynamics. But recently there has been considerable interest in understanding the interaction of evolutionary and ecological dynamics as coupled processes. However, in the context of complex multi-species ecosytems, especially where ecological and evolutionary timescales are similar, it is difficult to identify general organising principles that help us understand the structure and behaviour of complex ecosystems. Here we introduce a simple abstraction of coevolutionary interactions in a multi-species ecosystem. We model non-trophic ecological interactions based on a continuous but low-dimensional trait/niche space, where the location of each species in trait space affects the overlap of its resource utilisation with that of other species. The local depletion of available resources creates, in effect, a deformable fitness landscape that governs how the evolution of one species affects the selective pressures on other species. This enables us to study the coevolution of ecological interactions in an intuitive and easily visualisable manner. We observe that this model can exhibit either of the two behavioural modes discussed in the literature; namely, evolutionary stasis or Red Queen dynamics, i.e., continued evolutionary change. We find that which of these modes is observed depends on the lag or latency between the movement of a species in trait space and its effect on available resources. Specifically, if ecological change is nearly instantaneous compared to evolutionary change, stasis results; but conversely, if evolutionary timescales are closer to ecological timescales, such that resource depletion is not instantaneous on evolutionary timescales, then Red Queen dynamics result. We also observe that in the stasis mode, the overall utilisation of resources by the ecosystem is relatively efficient, with diverse species utilising different niches, whereas in the Red Queen mode the organisation of the ecosystem is such that species tend to clump together competing for overlapping resources. These models thereby suggest some basic conditions that influence the organisation of inter-species interactions and the balance of individual and collective adaptation in ecosystems, and likewise they also suggest factors that might be useful in engineering artificial coevolution
Effective interaction between helical bio-molecules
The effective interaction between two parallel strands of helical
bio-molecules, such as deoxyribose nucleic acids (DNA), is calculated using
computer simulations of the "primitive" model of electrolytes. In particular we
study a simple model for B-DNA incorporating explicitly its charge pattern as a
double-helix structure. The effective force and the effective torque exerted
onto the molecules depend on the central distance and on the relative
orientation. The contributions of nonlinear screening by monovalent counterions
to these forces and torques are analyzed and calculated for different salt
concentrations. As a result, we find that the sign of the force depends
sensitively on the relative orientation. For intermolecular distances smaller
than it can be both attractive and repulsive. Furthermore we report a
nonmonotonic behaviour of the effective force for increasing salt
concentration. Both features cannot be described within linear screening
theories. For large distances, on the other hand, the results agree with linear
screening theories provided the charge of the bio-molecules is suitably
renormalized.Comment: 18 pages, 18 figures included in text, 100 bibliog
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