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Search Results: 1 - 10 of 302974 matches for " Alex J Ntamatungiro "
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Human exposure to anopheline mosquitoes occurs primarily indoors, even for users of insecticide-treated nets in Luangwa Valley, South-east Zambia
Aklilu Seyoum, Chadwick H Sikaala, Javan Chanda, Dingani Chinula, Alex J Ntamatungiro, Moonga Hawela, John M Miller, Tanya L Russell, Olivier JT Bri?t, Gerry F Killeen
Parasites & Vectors , 2012, DOI: 10.1186/1756-3305-5-101
Abstract: Mosquitoes were collected by human landing catch in blocks of houses with either combined use of deltamethrin-based IRS and LLINs or LLINs alone. Human behaviour data were collected to estimate how much exposure to mosquito bites indoors and outdoors occurred at various times of the night for LLIN users and non-users.Anopheles funestus and An. quadriannulatus did not show preference to bite either indoors or outdoors: the proportions [95% confidence interval] caught indoors were 0.586 [0.303, 0.821] and 0.624 [0.324, 0.852], respectively. However, the overwhelming majority of both species were caught at times when most people are indoors. The proportion of mosquitoes caught at a time when most people are indoors were 0.981 [0.881, 0.997] and 0.897 [0.731, 0.965], respectively, so the proportion of human exposure to both species occuring indoors was high for individuals lacking LLINs (An. funestus: 0.983 and An. quadriannulatus: 0.970, respectively). While LLIN users were better protected, more than half of their exposure was nevertheless estimated to occur indoors (An. funestus: 0.570 and An. quadriannulatus: 0.584).The proportion of human exposure to both An. funestus and An. quadriannulatus occuring indoors was high in the area and hence both species might be responsive to further peri-domestic measures if these mosquitoes are susceptible to insecticidal products.
Repellent Plants Provide Affordable Natural Screening to Prevent Mosquito House Entry in Tropical Rural Settings—Results from a Pilot Efficacy Study
Frank C. Mng'ong'o, Joseph J. Sambali, Eustachkius Sabas, Justine Rubanga, Jaka Magoma, Alex J. Ntamatungiro, Elizabeth L. Turner, Daniel Nyogea, Jeroen H. J. Ensink, Sarah J. Moore
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0025927
Abstract: Sustained malaria control is underway using a combination of vector control, prompt diagnosis and treatment of malaria cases. Progress is excellent, but for long-term control, low-cost, sustainable tools that supplement existing control programs are needed. Conventional vector control tools such as indoor residual spraying and house screening are highly effective, but difficult to deliver in rural areas. Therefore, an additional means of reducing mosquito house entry was evaluated: the screening of mosquito house entry points by planting the tall and densely foliated repellent plant Lantana camara L. around houses. A pilot efficacy study was performed in Kagera Region, Tanzania in an area of high seasonal malaria transmission, where consenting families within the study village planted L. camara (Lantana) around their homes and were responsible for maintaining the plants. Questionnaire data on house design, socioeconomic status, malaria prevention knowledge, attitude and practices was collected from 231 houses with Lantana planted around them 90 houses without repellent plants. Mosquitoes were collected using CDC Light Traps between September 2008 and July 2009. Data were analysed with generalised negative binomial regression, controlling for the effect of sampling period. Indoor catches of mosquitoes in houses with Lantana were compared using the Incidence Rate Ratio (IRR) relative to houses without plants in an adjusted analysis. There were 56% fewer Anopheles gambiae s.s. (IRR 0.44, 95% CI 0.28–0.68, p<0.0001); 83% fewer Anopheles funestus s.s. (IRR 0.17, 95% CI 0.09–0.32, p<0.0001), and 50% fewer mosquitoes of any kind (IRR 0.50, 95% CI 0.38–0.67, p<0.0001) in houses with Lantana relative to controls. House screening using Lantana reduced indoor densities of malaria vectors and nuisance mosquitoes with broad community acceptance. Providing sufficient plants for one home costs US $1.50 including maintenance and labour costs, (30 cents per person). L. camara mode of action and suitability for mosquito control is discussed.
Preliminary Trial of Cover Cropping and Weed Control for Organic Rice  [PDF]
Gena R. Mahato, Anna McClung, Sixte Ntamatungiro, Surendra Singh, Meghnath Pokharel, Vince Wiley, Bihu Huang
American Journal of Plant Sciences (AJPS) , 2017, DOI: 10.4236/ajps.2017.811186
Abstract: The experiment site at UAPB agronomy farm was left undisturbed for several years for organic rice experiment. Soil samples taken in September 2015 showed that the experiment site was deficient with plant nutrients (NPK). Therefore, an organic fertilizer, Nature (8-5-5) was applied before planting mixture of crimson clover and winter wheat as cover crop in fall 2015. Biomass samples taken from the cover cropped land (CCL) and fallow land (FL) resulted in decrease in weed biomass by 33.36% and increase in total biomass by 46.78% in CCL than FL. Cover crops were incorporated one month before the rice sowing in June 2016. Fifteen rice cultivars were experimented for weed competition under water seeding cultivation method. Water seeding method was not effective to control the weeds as weeds dominated most of the rice plots since seedling stage. However, two rice cultivars namely Jasmine 85 and Rondo showed strong weed competition due to higher plant stand and better seedling establishment.
Family Forest Owners’ Motivation to Control Understory Vegetation: Implications for Consulting Forestry  [PDF]
Alex C. Londeau, Thomas J. Straka
Open Journal of Forestry (OJF) , 2013, DOI: 10.4236/ojf.2013.34016
Abstract:

Forest vegetation management has evolved as a recognized component of intensive forest management practice. It involves the management of competing vegetation necessary to obtain the high yields expected in modern forest plantations via control of interfering plants that influence regeneration outcome, impact timber stand development, and limit native plant and wildlife diversity. It includes cultural control, fire control, mechanical control, biological control, and chemical control. The public perception of forest vegetation management, especially chemical control, is sometimes negative due to health and environmental concerns. It is an important tool in the forest management alternatives available to consulting foresters managing family forest lands (the vast majority of private forest land in the United States). We report on a study that addresses the motivations of family forest owners that implement forest vegetation management practices and the motivation of those who chose not to implement after forester recommendations to do so. For those who do implement forest vegetation management, improvement of wildlife habitat and increased timber growth was the main motivation. For those who did not, cost was the main concern. Size of forest holding plays a major role in determining who will practice intensive forestry.

 

A Lie connection between Hamiltonian and Lagrangian optics
Alex J. Dragt
Discrete Mathematics & Theoretical Computer Science , 1997,
Abstract: It is shown that there is a non-Hamiltonian vector field that provides a Lie algebraic connection between Hamiltonian and Lagrangian optics. With the aid of this connection, geometrical optics can be formulated in such a way that all aberrations are attributed to ray transformations occurring only at lens surfaces. That is, in this formulation there are no aberrations arising from simple transit in a uniform medium. The price to be paid for this formulation is that the Lie algebra of Hamiltonian vector fields must be enlarged to include certain non-Hamiltonian vector fields. It is shown that three such vector fields are required at the level of third-order aberrations, and sufficient machinery is developed to generalize these results to higher order.
What is a Systems Approach?
Alex J. Ryan
Physics , 2008,
Abstract: What is a systems approach? The first step towards answering this question is an understanding of the history of the systems movement, which includes a survey of contemporary systems discourse. In particular, I examine how systems researchers differentiated their contribution from mechanistic science - but also from holistic doctrines; and identify the similarities and sharpest differences between complex systems and other systems approaches. Having set the scene, the second step involves developing a definition of 'system' consistent with the spirit of the systems approach.
Emergence is coupled to scope, not level
Alex J. Ryan
Physics , 2006,
Abstract: Since its application to systems, emergence has been explained in terms of levels of observation. This approach has led to confusion, contradiction, incoherence and at times mysticism. When the idea of level is replaced by a framework of scope, resolution and state, this confusion is dissolved. We find that emergent properties are determined by the relationship between the scope of macrostate and microstate descriptions. This establishes a normative definition of emergent properties and emergence that makes sense of previous descriptive definitions of emergence. In particular, this framework sheds light on which classes of emergent properties are epistemic and which are ontological, and identifies fundamental limits to our ability to capture emergence in formal systems.
The helix--coil transition on the worm--like chain
Alex J. Levine
Physics , 2004,
Abstract: I propose a variation of the standard worm--like chain model to account for internal order parameter (helix/coil) fields on the polymer chain. This internal order parameter field influences polymer conformational statistics by locally modifying the persistence length of the chain. Using this model, I make predictions for the bending and stretching response of an alpha-helical domain of a protein. In particular, I show that alpha-helical protein domains will buckle under applied torque. This highly nonlinear elastic behavior may be important in the understanding of allosteric control of biochemical pathways.
Fusion Rules for Affine Kac-Moody Algebras
Alex J. Feingold
Mathematics , 2002,
Abstract: This is an expository introduction to fusion rules for affine Kac-Moody algebras, with major focus on the algorithmic aspects of their computation and the relationship with tensor product decompositions. Many explicit examples are included with figures illustrating the rank 2 cases. New results relating fusion coefficients to tensor product coefficients are proved, and a conjecture is given which shows that the Frenkel-Zhu affine fusion rule theorem can be seen as a beautiful generalization of the Parasarathy-Ranga Rao-Varadarajan tensor product theorem. Previous work of the author and collaborators on a different approach to fusion rules from elementary group theory is also explained.
A p21-Activated Kinase Is Required for Conidial Germination in Penicillium marneffei
Kylie J Boyce,Alex Andrianopoulos
PLOS Pathogens , 2007, DOI: 10.1371/journal.ppat.0030162
Abstract: Asexual spores (conidia) are the infectious propagules of many pathogenic fungi, and the capacity to sense the host environment and trigger conidial germination is a key pathogenicity determinant. Germination of conidia requires the de novo establishment of a polarised growth axis and consequent germ tube extension. The molecular mechanisms that control polarisation during germination are poorly understood. In the dimorphic human pathogenic fungus Penicillium marneffei, conidia germinate to produce one of two cell types that have very different fates in response to an environmental cue. At 25 °C, conidia germinate to produce the saprophytic cell type, septate, multinucleate hyphae that have the capacity to undergo asexual development. At 37 °C, conidia germinate to produce the pathogenic cell type, arthroconidiating hyphae that liberate uninucleate yeast cells. This study shows that the p21-activated kinase pakA is an essential component of the polarity establishment machinery during conidial germination and polarised growth of yeast cells at 37 °C but is not required for germination or polarised growth at 25 °C. Analysis shows that the heterotrimeric G protein α subunit GasC and the CDC42 orthologue CflA lie upstream of PakA for germination at both temperatures, while the Ras orthologue RasA only functions at 25 °C. These findings suggest that although some proteins that regulate the establishment of polarised growth in budding yeast are conserved in filamentous fungi, the circuitry and downstream effectors are differentially regulated to give rise to distinct cell types.
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