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1

Trypanosomiasis vector control in Africa and Latin America  

Microsoft Academic Search

Vectors of trypanosomiasis – tsetse (Glossinidae) in Africa, kissing-bugs (Triatominae) in Latin America – are very different insects but share demographic characteristics that render them highly vulnerable to available control methods. For both, the main operational problems relate to re-invasion of treated areas, and the solution seems to be in very large-scale interventions covering biologically-relevant areas rather than adhering to

Chris J Schofield; John P Kabayo

2008-01-01

2

Trypanosomiasis control.  

PubMed

In July 2000, Heads of State of the 36th Session of the Organisation for African Unity signed a potentially important declaration on African trypanosomiasis, urging member states "to act collectively to rise to the challenge of eliminating the problem through concerted efforts in mobilising the necessary human, financial and material resources required to render Africa tsetse-free within the shortest time possible". To many, such an ambitious dream is received with some scepticism, recalling the doubts that surrounded a similar declaration signed in Brasilia in 1991, which paved the way for the Southern Cone Initiative against American trypanosomiasis (Chagas disease). True, the two diseases are quite different. But the operational challenges are quite similar, and there are sufficient biological parallels to suggest that the Latin American experience in controlling Chagas disease may provide a useful model for the control of African trypanosomiasis. PMID:11334951

Schofield, C J; Maudlin, I

2001-05-01

3

Evaluating paratransgenesis as a potential control strategy for African trypanosomiasis.  

PubMed

Genetic-modification strategies are currently being developed to reduce the transmission of vector-borne diseases, including African trypanosomiasis. For tsetse, the vector of African trypanosomiasis, a paratransgenic strategy is being considered: this approach involves modification of the commensal symbiotic bacteria Sodalis to express trypanosome-resistance-conferring products. Modified Sodalis can then be driven into the tsetse population by cytoplasmic incompatibility (CI) from Wolbachia bacteria. To evaluate the effectiveness of this paratransgenic strategy in controlling African trypanosomiasis, we developed a three-species mathematical model of trypanosomiasis transmission among tsetse, humans, and animal reservoir hosts. Using empirical estimates of CI parameters, we found that paratransgenic tsetse have the potential to eliminate trypanosomiasis, provided that any extra mortality caused by Wolbachia colonization is low, that the paratransgene is effective at protecting against trypanosome transmission, and that the target tsetse species comprises a large majority of the tsetse population in the release location. PMID:23967363

Medlock, Jan; Atkins, Katherine E; Thomas, David N; Aksoy, Serap; Galvani, Alison P

2013-08-15

4

The epidemiology and control of human African trypanosomiasis.  

PubMed

Human African trypanosomiasis is caused by Trypanosoma brucei gambiense in West and Central Africa, and by Trypanosoma brucei rhodesiense in East and southern Africa. In recent years there has been a dramatic resurgence of Gambian trypanosomiasis in Central Africa, especially in the Democratic Republic of Congo, Angola and Sudan. The disease is quiescent in most of West Africa, as is Rhodesian trypanosomiasis the other side of the continent. The epidemiology of Gambian trypanosomiasis is reviewed in detail. The long duration of infection in human hosts with cycles of intermittent parasitaemia, the vectors' feeding habits and the intensity of human-fly contact are the major determinants of the dynamics of transmission of this parasite. The development of immunity may lead to a reduction in the fraction of the population that is susceptible to infection and the burning out of epidemics after 20 to 30 years. So far, the acquired immune deficiency syndrome pandemic has had no impact on the epidemiology of Gambian trypanosomiasis. A brief review of the epidemiology of Rhodesian trypanosomiasis highlights the differences from Gambian trypanosomiasis that, to some extent, explain its lower propensity to cause epidemics: it is a more aggressive disease that rapidly kills its human host, and its transmission involves mostly domestic and game animals, humans being in most circumstances an accidental host. The various methods and strategies for the surveillance and control of both diseases are reviewed. PMID:11461032

Pépin, J; Méda, H A

2001-01-01

5

Prospects for Developing Odour Baits To Control Glossina fuscipes spp., the Major Vector of Human African Trypanosomiasis  

Microsoft Academic Search

We are attempting to develop cost-effective control methods for the important vector of sleeping sickness, Glossina fuscipes spp. Responses of the tsetse flies Glossina fuscipes fuscipes (in Kenya) and G. f. quanzensis (in Democratic Republic of Congo) to natural host odours are reported. Arrangements of electric nets were used to assess the effect of cattle-, human- and pig-odour on (1)

Maurice O. Omolo; Ahmed Hassanali; Serge Mpiana; Johan Esterhuizen; Jenny Lindh; Mike J. Lehane; Philippe Solano; Jean Baptiste Rayaisse; Glyn A. Vale; Steve J. Torr; Inaki Tirados

2009-01-01

6

Human African trypanosomiasis: Epidemiology and control.  

PubMed

Human African trypanosomiasis (HAT), or sleeping sickness, describes not one but two discrete diseases: that caused by Trypanosoma brucei rhodesiense and that caused by T. b. gambiense. The Gambian form is currently a major public health problem over vast areas of central and western Africa, while the zoonotic, Rhodesian form continues to present a serious health risk in eastern and southern Africa. The two parasites cause distinct clinical manifestations, and there are significant differences in the epidemiology of the diseases caused. We discuss the differences between the diseases caused by the two parasites, with an emphasis on disease burden, reservoir hosts, transmission, diagnosis, treatment and control. We analyse how these differences impacted on historical disease control trends and how they can inform contemporary treatment and control options. We consider the optimal ways in which to devise HAT control policies in light of the differing biology and epidemiology of the parasites, and emphasise, in particular, the wider aspects of control policy, outlining the responsibilities of individuals, governments and international organisations in control programmes. PMID:16735165

Fèvre, E M; Picozzi, K; Jannin, J; Welburn, S C; Maudlin, I

2006-01-01

7

Predicting the effect of climate change on African trypanosomiasis: integrating epidemiology with parasite and vector biology  

PubMed Central

Climate warming over the next century is expected to have a large impact on the interactions between pathogens and their animal and human hosts. Vector-borne diseases are particularly sensitive to warming because temperature changes can alter vector development rates, shift their geographical distribution and alter transmission dynamics. For this reason, African trypanosomiasis (sleeping sickness), a vector-borne disease of humans and animals, was recently identified as one of the 12 infectious diseases likely to spread owing to climate change. We combine a variety of direct effects of temperature on vector ecology, vector biology and vector–parasite interactions via a disease transmission model and extrapolate the potential compounding effects of projected warming on the epidemiology of African trypanosomiasis. The model predicts that epidemics can occur when mean temperatures are between 20.7°C and 26.1°C. Our model does not predict a large-range expansion, but rather a large shift of up to 60 per cent in the geographical extent of the range. The model also predicts that 46–77 million additional people may be at risk of exposure by 2090. Future research could expand our analysis to include other environmental factors that influence tsetse populations and disease transmission such as humidity, as well as changes to human, livestock and wildlife distributions. The modelling approach presented here provides a framework for using the climate-sensitive aspects of vector and pathogen biology to predict changes in disease prevalence and risk owing to climate change.

Moore, Sean; Shrestha, Sourya; Tomlinson, Kyle W.; Vuong, Holly

2012-01-01

8

Predicting the effect of climate change on African trypanosomiasis: integrating epidemiology with parasite and vector biology.  

PubMed

Climate warming over the next century is expected to have a large impact on the interactions between pathogens and their animal and human hosts. Vector-borne diseases are particularly sensitive to warming because temperature changes can alter vector development rates, shift their geographical distribution and alter transmission dynamics. For this reason, African trypanosomiasis (sleeping sickness), a vector-borne disease of humans and animals, was recently identified as one of the 12 infectious diseases likely to spread owing to climate change. We combine a variety of direct effects of temperature on vector ecology, vector biology and vector-parasite interactions via a disease transmission model and extrapolate the potential compounding effects of projected warming on the epidemiology of African trypanosomiasis. The model predicts that epidemics can occur when mean temperatures are between 20.7°C and 26.1°C. Our model does not predict a large-range expansion, but rather a large shift of up to 60 per cent in the geographical extent of the range. The model also predicts that 46-77 million additional people may be at risk of exposure by 2090. Future research could expand our analysis to include other environmental factors that influence tsetse populations and disease transmission such as humidity, as well as changes to human, livestock and wildlife distributions. The modelling approach presented here provides a framework for using the climate-sensitive aspects of vector and pathogen biology to predict changes in disease prevalence and risk owing to climate change. PMID:22072451

Moore, Sean; Shrestha, Sourya; Tomlinson, Kyle W; Vuong, Holly

2011-11-09

9

A review of recent knowledge of the ecology of the main vectors of trypanosomiasis*  

PubMed Central

In this survey of recent ecological research on the main vectors of trypanosomiasis in those countries of East, Central and West Africa that are not predominantly French-speaking, the authors, after outlining the distribution of tsetse flies and the type of country in which they occur, discuss the direct and indirect effects of climate on these insects—particularly on their physiological water balance and on pupal fat reserves—and their recent advances into new areas. They review the considerable work that has been done on the resting habits and breeding-sites of different Glossina species, knowledge of which is important for effective control, and research on predators of pupae and adult flies and on the feeding activity of tsetse flies. Means of assessing populations and various factors affecting the size and nutritional status of tsetse flies are also discussed, as is the effect on the fly population of artificial changes in the habitat. Finally, a plea is made for a revision of present methods of land use and stock management, if full advantage is to be taken of achievements in fly control.

Langridge, W. P.; Kernaghan, R. J.; Glover, P. E.

1963-01-01

10

Tsetse fly control and trypanosomiasis in Africa, quo vadis?  

PubMed

National and international efforts to eradicate tsetse fly-borne human and animal trypanosomiasis are critically evaluated, and possible reasons for their failure in many cases are discussed. Some formerly performed campaigns in specific areas with positive results cannot be taken as examples to solve the main problems. In future, a significant reduction of trypanosomiasis cases will be possible to achieve only if a concerted long-term Pan-African approach, based on financial security, the continuity of expert staff, and a well-planned, ecologically sound land use, is generally accepted. PMID:21104211

Dräger, N

2010-11-19

11

Challenges in the control of Human African Trypanosomiasis in the Mpika district of Zambia  

PubMed Central

Background Human African Trypanosomiasis is one of the Neglected Tropical Diseases that is targeted for elimination by the World Health Organization. Strong health delivery system in endemic countries is required for a control program to eliminate this disease. In Zambia, Human African Trypanosomiasis is lowly endemic in the northeastern part of the country. Findings We conducted a cross-sectional survey of health institutions in Mpika district in Northern Province of Zambia from 9th to 23rd November 2011. The aim of this study was to assess current health delivery system in the management of Human African Trypanosomiasis cases in Mpika district, Northern Province of Zambia. Ten health institutions were covered in the survey. Two structured questionnaires targeting health workers were used to collect the data on general knowledge on HAT and state of health care facilities in relation to HAT management from the surveyed health institution. Only 46% of the 28 respondents scored more than 50% from the questionnaire on general knowledge about Human African Trypanosomiasis disease. None of the respondents knew how to differentiate the two clinical stages of Human African Trypanosomiasis disease. There were only three medical doctors to attend to all Human African Trypanosomiasis cases and other diseases at the only diagnostic and treatment hospital in Mpika district. The supply of antitrypanosomal drugs to the only treatment centre was erratic. Only one refresher course on Human African Trypanosomiasis case diagnosis and management for health staff in the district had been organized by the Ministry of Health in conjunction with the World Health Organization in the district in 2009. The referral system for suspected Human African Trypanosomiasis cases from Rural Health Centres (RHCs) to the diagnostic/treatment centre was inefficient. Conclusions There are a number of challenges that have been identified and need to be addressed if Human African Trypanosomiasis is to be eliminated in a lowly endemic country such as Zambia. These include shortage of trained health workers, inadequate diagnostic and treatment centres, lack of more sensitive laboratory diagnostic techniques, shortage of trypanosomicides among others discussed in detail here.

2013-01-01

12

African Trypanosomiasis.  

National Technical Information Service (NTIS)

African trypanosomiasis is infection by protozoan hemoflagellates of the Trypanosoma brucei complex, subspecies of which cause disease in humans: Trypanosoma brucei gambiense causes Gambian (chronic) trypanosomiasis and Trypanosoma brucei rhodesiense caus...

M. K. Klassen-Fischer R. C. Neafie W. M. Meyers

2011-01-01

13

Modeling the Control of Trypanosomiasis Using Trypanocides or Insecticide-Treated Livestock  

Microsoft Academic Search

BackgroundIn Uganda, Rhodesian sleeping sickness, caused by Trypanosoma brucei rhodesiense, and animal trypanosomiasis caused by T. vivax and T. congolense, are being controlled by treating cattle with trypanocides and\\/or insecticides. We used a mathematical model to identify treatment coverages required to break transmission when host populations consisted of various proportions of wild and domestic mammals, and reptiles.Methodology\\/Principal FindingsAn Ro model

John W. Hargrove; Rachid Ouifki; Damian Kajunguri; Glyn A. Vale; Stephen J. Torr

2012-01-01

14

Short-course eflornithine in Gambian trypanosomiasis: a multicentre randomized controlled trial  

Microsoft Academic Search

Objective A randomized controlled trial was conducted to determine whether 7 days of intravenous eflornithine (100 mg\\/kg every 6 h) was as effective as the standard 14-day regimen in the treatment of late-stage Trypanosoma brucei gambiense trypanosomiasis. Methods A total of 321 patients (274 new cases, 47 relapsing cases) were randomized at four participating centres in Congo, Cote d'Ivoire, the

Jacques Pepin; Nzambi Khonde; Faustine Maiso; Felix Doua; Shabbar Jaffar; Stephane Ngampo; Bokelo Mpia; Dawson Mbulamberi; Felix Kuzoe

15

Modelling trypanosomiasis prevalence and periodic epidemics and epizootics.  

PubMed

Existing mathematical models of trypanosomiasis epidemiology and epizootiology are extended by including some relevant biology of the disease vector, the tsetse fly. Rickettsia-like organisms, or RLO, are a vertically transmitted symbiont of tsetse, which confer an increased susceptibility to trypanosomiasis infection. Tsetse populations are also limited by density-dependent starvation. Modelling leads to the prediction of a stable dimorphism with a fraction of tsetse possessing RLO. The equilibrium prevalence of trypanosomiasis in the vertebrate hosts is no longer in RLO models determined simply by such traditional parameters as vectorial capacity. Only the RLO-positive tsetse carry infection, and their number is itself regulated by trypanosomiasis prevalence. The result of a naive model is that controlling tsetse numbers does not decrease prevalence until all tsetse are RLO-positive. However, under the density-dependent starvation model derived in this paper, the relative mortality of RLO-positive flies is greater at lower tsetse numbers. This tips the balance towards lower equilibrium prevalence of trypanosomiasis as tsetse numbers are decreased. The presence of RLO also gives rise to long-term oscillations in trypanosomiasis prevalence in humans and animals. However, when another mechanism that can also cause periodic epizootics (of shorter periodicity) is included, namely host immunity, the two epizootic processes combine to produce periodic epizootics (and therefore epidemics) at a single frequency. There are two decaying modes, one in which the tsetse population size quickly reaches equilibrium in a few weeks, and a second very slowly decaying mode in which host immunity and RLO effects interact. The equilibrium reached is shown to be asymptotically stable. In view of the seeming importance of RLO in trypanosomiasis epidemiology, it is important that field biologists enable RLO models to be validated by measuring the proportion of tsetse with RLO, in conjunction with vector density and trypanosomiasis prevalence and incidence in tsetse and vertebrate hosts. PMID:1302761

Baker, R D

1992-01-01

16

Modeling the Control of Trypanosomiasis Using Trypanocides or Insecticide-Treated Livestock  

PubMed Central

Background In Uganda, Rhodesian sleeping sickness, caused by Trypanosoma brucei rhodesiense, and animal trypanosomiasis caused by T. vivax and T. congolense, are being controlled by treating cattle with trypanocides and/or insecticides. We used a mathematical model to identify treatment coverages required to break transmission when host populations consisted of various proportions of wild and domestic mammals, and reptiles. Methodology/Principal Findings An Ro model for trypanosomiasis was generalized to allow tsetse to feed off multiple host species. Assuming populations of cattle and humans only, pre-intervention Ro values for T. vivax, T. congolense, and T. brucei were 388, 64 and 3, respectively. Treating cattle with trypanocides reduced R0 for T. brucei to <1 if >65% of cattle were treated, vs 100% coverage necessary for T. vivax and T. congolense. The presence of wild mammalian hosts increased the coverage required and made control of T. vivax and T. congolense impossible. When tsetse fed only on cattle or humans, R0 for T. brucei was <1 if 20% of cattle were treated with insecticide, compared to 55% for T. congolense. If wild mammalian hosts were also present, control of the two species was impossible if proportions of non-human bloodmeals from cattle were <40% or <70%, respectively. R0 was <1 for T. vivax only when insecticide treatment led to reductions in the tsetse population. Under such circumstances R0<1 for T. brucei and T. congolense if cattle make up 30% and 55%, respectively of the non-human tsetse bloodmeals, as long as all cattle are treated with insecticide. Conclusions/Significance In settled areas of Uganda with few wild hosts, control of Rhodesian sleeping sickness is likely to be much more effectively controlled by treating cattle with insecticide than with trypanocides.

Hargrove, John W.; Ouifki, Rachid; Kajunguri, Damian; Vale, Glyn A.; Torr, Stephen J.

2012-01-01

17

Vector-borne disease control in sub-Saharan Africa: A necessary but partial vision of development  

Microsoft Academic Search

A comparative analysis of efforts to control four major vector-borne diseases that plague agricultural development in sub-Saharan Africa — onchocerciasis (river blindness), bovine trypanosomiasis, malaria, and East Coast Fever — reveals numerous similarities in the technical reasons why control programs break down. The authors conclude that there is an urgent need to develop simpler control technologies and to pay more

Martin I. Meltzer

1996-01-01

18

Fluidic thrust vector control  

Microsoft Academic Search

The design and testing of a fluidic control nozzle for tactical missile thrust vector control (TVC) are discussed. Attention is given to a nozzle with a circular cross section up to the point of flow separation, two control ports that alternately open and close, and a nozzle extension downstream of the control ports being a two-dimensional rectangular slot. Design of

V. E. Haloulakos

1982-01-01

19

Financial analysis of animal trypanosomiasis control using cypermethrin pour-on in Kenya.  

PubMed

The financial impact of use of cypermethrin pour-on (Ectopor(R)) in control of animal trypanosomiosis was determined in a trial undertaken by the Kenya Trypanosomiasis Research Institute (KETRI). This trial started in December 1990 and ended in February 1992. It was undertaken in two adjacent ranches in the coast province of Kenya. The trial site was in an area of high apparent density (AD) of tsetse flies, and at the start of the trial no cattle were kept in this area. Cypermethrin was applied fortnightly to the 1100 steers which were kept in pour-on ranch 'A' while another 100 steers were kept in control ranch 'B' to act as control sentinels. From the main pour-on group, 100 animals were identified as the pour-on sentinels and compared to the control sentinels which received no pour-on.Pour-on application led to a significant decrease in the tsetse AD in the pour-on ranch A to 90% of the initial AD in some areas. The animals treated with pour-on had a significantly higher mean packed-cell volume (PCV). The weekly prevalence of trypanosome infections in animals treated with pour-on was <4% with only one exception when it was <10%. In the control animals, the prevalence ranged between 10 and 50% (with a few exceptions when it was <10%). The incidence of tick-borne diseases was lower in the pour-on animals. The mean monthly weights of the pour-on animals was significantly higher, and at the end of the trial the pour-on animals had a mean weight gain of 136.70+/-16.7kg while the control animals had gained 97.16+/-22.6kg. The financial net return of using cypermethrin pour-on was positive and the financial rate of return of 122.6% indicated that use of the pour-on was highly beneficial despite the high cost of the product. PMID:10760405

Kamau, S W; Omukuba, J; Kiragu, J; Masika, P; Ndung'u, J M; Wachira, P; Mehlitz, D

2000-04-28

20

Fluidic thrust vector control  

NASA Astrophysics Data System (ADS)

The design and testing of a fluidic control nozzle for tactical missile thrust vector control (TVC) are discussed. Attention is given to a nozzle with a circular cross section up to the point of flow separation, two control ports that alternately open and close, and a nozzle extension downstream of the control ports being a two-dimensional rectangular slot. Design of the TVC system involved characterizing the flow and the sensitivity parameters, the dynamic response, and the performance of hot-gas firings. The test firings verified the feasibility of a nozzle that could withstand 5000 F, the use of thrust vector angles of over 20 deg. A dynamic model test demonstrated a repeatable performance with pressures up to 2000 psia, driving frequencies up to 50 Hz, and a response of 10-15 msec. Adjustment of the chamber pressures permitted equivalent performance using with different heat ratios during cold dynamic tests with CH4.

Haloulakos, V. E.

21

Vector control in developed countries  

PubMed Central

The recent rapid growth of California's population, leading to competition for space between residential, industrial and agricultural interests, the development of its water resources and increasing water pollution provide the basic ingredients of its present vector problems. Within the past half-century, the original mosquito habitats provided by nature have gradually given place to even more numerous and productive habitats of man-made character. At the same time, emphasis in mosquito control has shifted from physical to chemical, with the more recent extension to biological approaches as well. The growing domestic fly problem, continuing despite the virtual disappearance of the horse, is attributable to an increasing amount of organic by-products, stemming from growing communities, expanding industries and changing agriculture. The programme for the control of disease vectors and pest insects and animals directs its major effort to the following broad areas: (1) water management (including land preparation), (2) solid organic wastes management (emphasizing utilization), (3) community management (including design, layout, and storage practices of buildings and grounds), and (4) recreational area management (related to wildlife management). It is apparent that vector control can often employ economics as an ally in securing its objectives. Effective organization of the environment to produce maximum economic benefits to industry, agriculture, and the community results generally in conditions unfavourable to the survival of vector and noxious animal species. Hence, vector prevention or suppression is preferable to control as a programme objective.

Peters, Richard F.

1963-01-01

22

Trypanosomiasis: African and American  

Microsoft Academic Search

Human African trypanosomiasis has increased in many endemic areas in recent years. It is caused by Trypanosoma brucei gambiense or T. b. rhodesiense, and is transmitted by the tsetse fly. Diagnosis is difficult, particularly in the West African type, in which organisms are scanty. Determination of the stage of infection (early haemolymphatic stage or late meningoencephalitic stage) is also problematic,

Sanjeev Krishna; August Stich

2005-01-01

23

Feedback control for counterflow thrust vectoring  

Microsoft Academic Search

Thrust vector control is used to increase the maneuverability of aircraft. In current aircraft it is implemented using movable control surfaces such as vanes and flaps. Counterflow thrust vectoring (CFTV) is a fluidic approach to thrust vectoring that has the potential to improve on the conventional approaches by reducing weight and increasing the reaction speed. Open loop implementation of CFTV

Emmanuel G. Collins; Yanan Zhao; F. Alvi; M. I. Alidu; P. J. Strykowski

2004-01-01

24

Insecticide resistance and vector control.  

PubMed

Insecticide resistance has been a problem in all insect groups that serve as vectors of emerging diseases. Although mechanisms by which insecticides become less effective are similar across all vector taxa, each resistance problem is potentially unique and may involve a complex pattern of resistance foci. The main defense against resistance is close surveillance of the susceptibility of vector populations. We describe the mechanisms of insecticide resistance, as well as specific instances of resistance emergence worldwide, and discuss prospects for resistance management and priorities for detection and surveillance. PMID:19785227

Brogdon, William G; McAllister, Janet C

2004-01-01

25

Problems of diagnosis of trypanosomiasis*  

PubMed Central

Diagnostic problems in trypanosomiasis arise from the inadequacy of current diagnostic procedures. This inadequacy deprives the clinician of essential data, hinders individual therapy and therapeutic control programmes, and makes suspect many conclusions drawn from previous experimental work. In this paper the author examines alternative methods of diagnosis, emphasizing cultivation and immunological procedures. An independent standard for diagnostic evaluation is available with the culture method. Comparison indicates that conventional procedures are frequently in error and that the error is always an underestimation, which may reach 20%-25% or more. The culture method has proved to be sensitive, reliable, usable under African field and hospital conditions, and applicable to isolation of Trypanosoma gambiense and T. rhodesiense from both blood and spinal fluid. Complement-fixation is the most widely used of the immunological reactions available. Procedures and results are reviewed and possibilities both with this method and others are discussed. Continuing research on diagnostic methods is needed, and certain practical difficulties in such a continuing research programme are discussed.

Weinman, David

1963-01-01

26

Vector control activities. Fiscal year, 1982  

SciTech Connect

The goal of the TVA Vector Control Program is to protect the public from potential vectors of disease by controlling medically-important arthropod pests that are propagated on TVA lands or waters. In addition, freedom from annoying mosquitoes and other blood-sucking pests permits the development, use, and full enjoyment of the vast recreational opportunities offered by the many miles of freshwater lakes. To attain this goal the program is divided into operations and support studies. The support studies are designed to improve the operational effectiveness and efficiency of the control program and to identify other vector control problems that require TVA attention and study. Specifically, activities concerning water level management of TVA lakes, dewatering projects, plant growth control, drainage and insect control programs are detailed. Further, report is made of post-impoundment surveys, soil sampling studies of Mosquite larvae and ecological mosquito management studies.

Pickard, E.; Cooney, J.C.; McDuff, B.R.

1983-06-01

27

African trypanosomiasis and antibodies: implications for vaccination, therapy and diagnosis.  

PubMed

African trypanosomiasis causes devastating effects on human populations and livestock herds in large parts of sub-Saharan Africa. Control of the disease is hampered by the lack of any efficient vaccination results in a field setting, and the severe side effects of current drug therapies. In addition, with the exception of Trypanosoma brucei gambiense infections, the diagnosis of trypanosomiasis has to rely on microscopic analysis of blood samples, as other specific tools are nonexistent. However, new developments in biotechnology, which include loop-mediated isothermal amplification as an adaptation to conventional PCR, as well as the antibody engineering that has allowed the development of Nanobody technology, offer new perspectives in both the detection and treatment of trypanosomiasis. In addition, recent data on parasite-induced B-cell memory destruction offer new insights into mechanisms of vaccine failure, and should lead us towards new strategies to overcome trypanosome defenses operating against the host immune system. PMID:19824795

Magez, Stefan; Radwanska, Magdalena

2009-10-01

28

Integrated vector management for malaria control  

PubMed Central

Integrated vector management (IVM) is defined as "a rational decision-making process for the optimal use of resources for vector control" and includes five key elements: 1) evidence-based decision-making, 2) integrated approaches 3), collaboration within the health sector and with other sectors, 4) advocacy, social mobilization, and legislation, and 5) capacity-building. In 2004, the WHO adopted IVM globally for the control of all vector-borne diseases. Important recent progress has been made in developing and promoting IVM for national malaria control programmes in Africa at a time when successful malaria control programmes are scaling-up with insecticide-treated nets (ITN) and/or indoor residual spraying (IRS) coverage. While interventions using only ITNs and/or IRS successfully reduce transmission intensity and the burden of malaria in many situations, it is not clear if these interventions alone will achieve those critical low levels that result in malaria elimination. Despite the successful employment of comprehensive integrated malaria control programmes, further strengthening of vector control components through IVM is relevant, especially during the "end-game" where control is successful and further efforts are required to go from low transmission situations to sustained local and country-wide malaria elimination. To meet this need and to ensure sustainability of control efforts, malaria control programmes should strengthen their capacity to use data for decision-making with respect to evaluation of current vector control programmes, employment of additional vector control tools in conjunction with ITN/IRS tactics, case-detection and treatment strategies, and determine how much and what types of vector control and interdisciplinary input are required to achieve malaria elimination. Similarly, on a global scale, there is a need for continued research to identify and evaluate new tools for vector control that can be integrated with existing biomedical strategies within national malaria control programmes. This review provides an overview of how IVM programmes are being implemented, and provides recommendations for further development of IVM to meet the goals of national malaria control programmes in Africa.

Beier, John C; Keating, Joseph; Githure, John I; Macdonald, Michael B; Impoinvil, Daniel E; Novak, Robert J

2008-01-01

29

Vector control activities: Fiscal Year, 1986  

SciTech Connect

The program is divided into two major components - operations and support studies. The support studies are designed to improve the operational effectiveness and efficiency of the control program and to identify other vector control problems requiring TVA attention and study. Nonchemical methods of control are emphasized and are supplemented with chemical measures as needed. TVA also cooperates with various concerned municipalities in identifying blood-sucking arthropod pest problems and demonstrating control techniques useful in establishing abatement programs, and provides technical assistance to other TVA programs and organizations. The program also helps Land Between The Lakes (LBL) plan and conduct vector control operations and tick control research. Specific program control activities and support studies are discussed.

Not Available

1987-04-01

30

Conflict and human African trypanosomiasis.  

PubMed

Human African Trypanosomiasis (HAT) has reemerged in sub-Saharan Africa as a disease of major public health importance. The success of HAT elimination in sub-Saharan Africa is subject to the feasibility of controlling, eliminating, or mitigating the determinants of incidence in affected countries. Conflict has been widely recognized and cited as a contributing factor to the resurgence of HAT in many countries, as well as to continuing HAT incidence in politically unstable and resource-poor regions. Despite extensive anecdotal and qualitative recognition of the role of conflict, there has been no quantitative research of this topic at the population level in affected African countries. We characterize the qualitative and quantitative associations between HAT incidence and conflict-related processes in HAT-affected African countries over the past 30 years. HAT and conflict-related data were collected for 35 affected countries in sub-Saharan Africa for the years 1976-2004. Descriptive and univariate inferential statistics, as well as negative binomial regression modeling, are used to assess the associations between HAT and conflict. A space-time scan statistic is used to identify significant incidence clusters. Clusters of HAT incidence over the past 30 years have predominantly coincided with periods of conflict or socio-political instability. HAT cases occurred significantly more often in countries and during years with conflict, high political terror, and internationalized civil war. The results indicate a lag period between the start of conflict events and a peak in incidence of approximately 10 years. We recommend explicit consideration and quantification of socio-political measures such as conflict and terror indices in GIS (Geographic Information Systems)-based risk assessments for HAT policy and intervention. PMID:20619948

Berrang-Ford, Lea; Lundine, Jamie; Breau, Sebastien

2010-06-23

31

Thrust vector control using electric actuation  

Microsoft Academic Search

Presently, gimbaling of launch vehicle engines for thrust vector control is generally accomplished using a hydraulic system. In the case of the space shuttle solid rocket boosters and main engines, these systems are powered by hydrazine auxiliary power units. Use of electromechanical actuators would provide significant advantages in cost and maintenance. However, present energy source technologies such as batteries are

Robert T. Bechtel; David K. Hall

1995-01-01

32

40 CFR 258.22 - Disease vector control.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Disease vector control. 258.22 Section 258.22...Operating Criteria § 258.22 Disease vector control. (a) Owners or operators...control on-site populations of disease vectors using techniques appropriate for...

2009-07-01

33

40 CFR 258.22 - Disease vector control.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Disease vector control. 258.22 Section 258.22...Operating Criteria § 258.22 Disease vector control. (a) Owners or operators...control on-site populations of disease vectors using techniques appropriate for...

2010-07-01

34

40 CFR 258.22 - Disease vector control.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Disease vector control. 258.22 Section 258.22...Operating Criteria § 258.22 Disease vector control. (a) Owners or operators...control on-site populations of disease vectors using techniques appropriate for...

2013-07-01

35

Vector control of induction motor without shaft encoder  

Microsoft Academic Search

A method of torque control in induction motor drives that requires not shaft encoder is presented. Both the torque control and the speed control are based on vector control. The proposed scheme of vector control is based on the self-control of rotor flux velocity, which is controlled with the torque-producing current and the rotor flux derived from the stator voltages

T. Ohtani; N. Takada; K. Tanaka

1989-01-01

36

Toxic Side Effects of Drugs Used to Treat Chagas’ Disease (American Trypanosomiasis)  

Microsoft Academic Search

Chagas’ disease (American trypanosomiasis) is an endemic parasitic disease in some areas of Latin America. About 16-18 million persons are infected with the aetiological agent of the disease, Trypanosoma cruzi, and more than 100 million are living at risk of infection. There are different modes of infection: 1) via blood sucking vector insects infected with T. cruzi, accounting for 80-90%

José A Castro; María Montalto deMecca; Laura C Bartel

2006-01-01

37

Speed Sensorless Vector Control of an Induction Motor using Spiral Vector Model-ECKF and ANN Controller  

Microsoft Academic Search

This paper presents a speed sensorless vector control of an induction motor using an extended complex Kalman filter, a neural network, a spiral vector model and two sensors for tracking voltage and current of one phase of stator. The spiral vector model uses the spiral vector variables rotating counter clockwise in the complex plane. This model depends only on variables

M. Menaa; O. Touhami; R. Ibtiouen; M. Fadel

2007-01-01

38

The Biological Control of the Malaria Vector  

PubMed Central

The call for malaria control, over the last century, marked a new epoch in the history of this disease. Many control strategies targeting either the Plasmodium parasite or the Anopheles vector were shown to be effective. Yet, the emergence of drug resistant parasites and insecticide resistant mosquito strains, along with numerous health, environmental, and ecological side effects of many chemical agents, highlighted the need to develop alternative tools that either complement or substitute conventional malaria control approaches. The use of biological means is considered a fundamental part of the recently launched malaria eradication program and has so far shown promising results, although this approach is still in its infancy. This review presents an overview of the most promising biological control tools for malaria eradication, namely fungi, bacteria, larvivorous fish, parasites, viruses and nematodes.

Kamareddine, Layla

2012-01-01

39

The biological control of the malaria vector.  

PubMed

The call for malaria control, over the last century, marked a new epoch in the history of this disease. Many control strategies targeting either the Plasmodium parasite or the Anopheles vector were shown to be effective. Yet, the emergence of drug resistant parasites and insecticide resistant mosquito strains, along with numerous health, environmental, and ecological side effects of many chemical agents, highlighted the need to develop alternative tools that either complement or substitute conventional malaria control approaches. The use of biological means is considered a fundamental part of the recently launched malaria eradication program and has so far shown promising results, although this approach is still in its infancy. This review presents an overview of the most promising biological control tools for malaria eradication, namely fungi, bacteria, larvivorous fish, parasites, viruses and nematodes. PMID:23105979

Kamareddine, Layla

2012-09-19

40

Introducing control flow into vectorized code.  

SciTech Connect

Single instruction multiple data (SIMD) functional units are ubiquitous in modern microprocessors. Effective use of these SIMD functional units is essential in achieving the highest possible performance. Automatic generation of SIMD instructions in the presence of control flow is challenging, however, not only because SIMD code is hard to generate in the presence of arbitrarily complex control flow, but also because the SIMD code executing the instructions in all control paths may slow compared to the scalar original, which may bypass a large portion of the code. One promising technique introduced recently involves inserting branches-on-superword-condition-codes (BOSCCs) to bypass vector instructions. In this paper, we describe two techniques that improve on the previous approach. First, BOSCCs are generated in a nested fashion so that even BOSCCs themselves can be bypassed by other BOSCCs. Second, we generate all vec any instructions to bypass even some predicate-defining instructions. We implemented these techniques in a vectorizing compiler. On 14 kernels, the compiler achieves distinct speedups, including 1.99X over the previous technique that generates single-level BOSCCs and vec any ne only.

Shin, J.; Mathematics and Computer Science

2007-01-01

41

Experimental Study On Counter Flow Thrust Vector Control  

Microsoft Academic Search

Counter Flow Thrust Vectoring (CFTV) is possibly the most promising fluidic thrust vector control method for deflecting the exhaust thrust of a jet engine. CFTV works by generating a countercurrent shear layer in one side of a planar jet and hence by altering the transverse pressure gradient across the jet. Prediction and control of vector angle is the most important

Maria S. Madruga; Debopam Das; Paul J. Strykowski

2000-01-01

42

The generalized theory of indirect vector control for AC machines  

Microsoft Academic Search

The instantaneous torque produced by an AC machine is controllable when vector control is applied. However, the published papers on vector control deal with either induction machines or synchronous machines. A generalized vector-control theory is developed, considering a generalized AC machine as a salient-pole synchronous machine having three kinds of torque, i.e., the field torque, the reluctance torque, and the

S. Ogasawara; H. Akagi; A. Nabae

1988-01-01

43

Space vector PWM control of dual three-phase induction machine using vector space decomposition  

Microsoft Academic Search

The technique of vector space decomposition control of voltage source inverter fed dual three-phase induction machines is presented in this paper. By vector space decomposition, the analytical modeling and control of the machine are accomplished in three two-dimensional orthogonal subspaces and the dynamics of the electromechanical energy conversion related and the nonelectromechanical energy conversion related machine variables are thereby totally

Yifan Zhao; Thomas A. Lipo

1995-01-01

44

Characteristics of a confined jet thrust vector control nozzle  

Microsoft Academic Search

A study of confined jet thrust vector control (CJTVC) is presented. By isolating an area of flow separation within the body of a nozzle, CJTVC has the advantage over other thrust vector controls using secondary injection (SI) in that it can operate independent of altitude. This makes it ideal for applications in small missiles and spacecraft attitude control. In this

A. J. Porzio

1984-01-01

45

Paratransgenic Control of Vector Borne Diseases  

PubMed Central

Conventional methodologies to control vector borne diseases with chemical pesticides are often associated with environmental toxicity, adverse effects on human health and the emergence of insect resistance. In the paratransgenic strategy, symbiotic or commensal microbes of host insects are transformed to express gene products that interfere with pathogen transmission. These genetically altered microbes are re-introduced back to the insect where expression of the engineered molecules decreases the host's ability to transmit the pathogen. We have successfully utilized this strategy to reduce carriage rates of Trypanosoma cruzi, the causative agent of Chagas disease, in the triatomine bug, Rhodnius prolixus, and are currently developing this methodology to control the transmission of Leishmania donovani by the sand fly Phlebotomus argentipes. Several effector molecules, including antimicrobial peptides and highly specific single chain antibodies, are currently being explored for their anti-parasite activities in these two systems. In preparation for eventual field use, we are actively engaged in risk assessment studies addressing the issue of horizontal gene transfer from the modified bacteria to environmental microbes.

Hurwitz, Ivy; Fieck, Annabeth; Read, Amber; Hillesland, Heidi; Klein, Nichole; Kang, Angray; Durvasula, Ravi

2011-01-01

46

A Fuzzy based PI speed controller for indirect vector controlled induction motor drive  

Microsoft Academic Search

This paper presents the speed control scheme of indirect vector controlled induction motor (IM) drive. Voltage source inverter type space vector pulse width modulation (SVPWM) is used for PWM controlling scheme. An intelligent based on Fuzzy PI controller is developed for controlling the torque component Iq current of an IM. The complete vector control scheme of the IM drive incorporating

R. Arulmozhiyal; K. Baskaran; R. Manikandan

2011-01-01

47

Immobilization of game animals in trypanosomiasis research  

PubMed Central

The proximity of human populations to communities of large animals in Africa creates suitable conditions for the transmission of zoonotic diseases. Since the indiscriminate destruction of these communities to control zoonoses is highly undesirable, the epidemiological role of the animals must be properly assessed in order that alternative methods of control can be developed. For this purpose, techniques should be available to permit large animals to be examined alive. Immobilization techniques using various drugs were tried but only limited success was achieved with the species most likely to be involved in the transmission cycle of trypanosomiasis. In the study reported here, xylazine was the drug selected, one reason being that an antagonist was not required. The drug was administered from a distance by means of a projectile syringe shot from a special rifle. In seven attempts, two waterbuck (Kobus defassa) and one reedbuck (Redunca redunca) were sufficiently immobilized to be handled. The reactions of all seven animals, whether successfully immobilized or not, are discussed.

Allsopp, R.

1972-01-01

48

Vector control in some countries of Southeast Asia: comparing the vectors and the strategies.  

PubMed

The use of information on malaria vector behaviour in vector control is discussed in relation to the area of Southeast Asia comprising Cambodia, Laos, Myanmar, Thailand and Vietnam. The major vectors in the region are Anopheles dirus, An. minimus, An. maculatus and An. sundaicus, of which An. dirus is the most important. Options for vector control and the biological features of mosquitoes, which would make them amenable to control by these measures, are listed. The methods with the greatest potential for controlling each of the four vector species are described. Experiences of vector control by residual spraying, insecticide-treated nets and larva control and of personal protection against the four vectors are outlined, and it is noted that choice of control strategy is often determined by epidemiological, economic and political considerations, whilst entomological observations may help to explain failures of control and to indicate alternative strategies. Future research needs include basic entomological field studies using the most appropriate indicators to detect changes related to rapidly changing environmental conditions, such as loss of forest and climate change. Further studies of the efficacy of insecticide-treated mosquito nets, with greater attention to study design, are needed before it can be assumed that they will work in Southeast Asia. At the same time, research to improve sustainable utilization of nets is important, bearing in mind that nets are not the only means to control malaria and should not drain resources from supervision and training, which improve access to diagnosis and treatment of malaria and other diseases. Research is needed to make decisions on whether vector control is appropriate in different environments, and, if so, how to carry it out in different health systems. Researchers need to play a greater role in making operational research (entomological, epidemiological, social, economic and health systems research) of good quality an integral component of implementation programmes. PMID:7605123

Meek, S R

1995-04-01

49

Vector control of induction motor without shaft encoder  

Microsoft Academic Search

A method of introduction motor drive that requires no shaft encoder is presented. This system has both torque and speed controls that are performed by vector control. The vector-control scheme is based on a rotor-flux speed control, which is performed by torque-producing current and rotor flux, derived from the stator voltages and currents. If it is possible to obtain both

Tsugutoshi Ohtani; Noriyuki Takada; Koji Tanaka

1992-01-01

50

Rhodesian trypanosomiasis in a splenectomized patient.  

PubMed

We report the first apparent case of a splenectomized individual who developed severe trypanosomiasis with central nervous system involvement. The patient was a 41-year-old man who participated in an east African safari. Upon his return to the United States, the patient presented with an infection with Trypanosoma brucei rhodesiense that was treated successfully with suramin and melarsoprol. The onset of symptoms, laboratory studies, and disease progression did not differ from previously reported cases in the literature. The role of the spleen in trypanosomiasis is not well understood and the few reports available describe only animal models. This report suggests that asplenia had no apparent effect on the onset of symptoms and overall severity of illness. Further studies are necessary to ultimately define the role of the spleen in trypanosomiasis. PMID:10497985

Malesker, M A; Boken, D; Ruma, T A; Vuchetich, P J; Murphy, P J; Smith, P W

1999-09-01

51

African trypanosomiasis in the United States.  

PubMed

African trypanosomiasis of the Rhodesian variety occurred in an American who recently traveled to Tanzania. Skin findings included a fluctuant, indurated, tsetse-fly bite site (chancre) and a fleeting, erythematous, macular eruption. The diagnosis was confirmed by the presence of the organism in peripheral blood smears. The patient's condition responded to intravenous suramin. African trypanosomiasis should be included in the differential diagnosis of patients who have visited areas where this disease is endemic, and in whom the appropriate skin findings are present. PMID:6870320

Cochran, R; Rosen, T

1983-08-01

52

Population mobility and trypanosomiasis in Africa*  

PubMed Central

Population mobility has long been established as a feature of life in Africa south of the Sahara. Even though it appears to be a factor in the spread of sleeping-sickness there do not seem to have been serious epidemics until the latter part of the nineteenth century and the early decades of the twentieth century. Various types of population movement of the present day and their possible relevance to trypanosomiasis are discussed. Density of population and settlement patterns are also important. Some of the changes in these which are relevant to trypanosomiasis are outlined and the need for more detailed information on these and on population mobility is emphasized.

Prothero, R. Mansell

1963-01-01

53

The Vector Control Strategies for Multiphase Synchronous Motor Drive Systems  

Microsoft Academic Search

This paper studies the multiphase synchronous motor with symmetrical windings and multi-Y-windings displaced in turn by ¿o separately, the mathematical descriptions about which can be concluded as two models: single-windings and multi-windings models in M,T frame. Based on these models, the multiphase vector control strategy and multiphase multi-ply vector control strategy are proposed, so as to achieve the gas-flux-oriented control

Lin Hua; Zou Yunping; He Bi

2006-01-01

54

Space vector based current control schemes for voltage source inverters  

Microsoft Academic Search

Hysteresis controllers are very simple and fast schemes for current control in voltage source inverters. Their disadvantage, a much higher switching frequency compared to other PWM methods, can be distinctly reduced by applying space vector based two dimensional hysteresis controllers. Four different control schemes are discussed and compared: the conventional method with three independent phase current controllers and three space

D. Wuest; F. Jenni

1993-01-01

55

Addressing malaria vector control challenges in South Sudan: proposed recommendations.  

PubMed

Upon the signing of the Comprehensive Peace Agreement in 2005, the Republic of South Sudan (RSS) has faced a lot of challenges, such as a lack of infrastructure, human resources and an enormous burden of vector borne diseases including malaria. While a national malaria strategic plan 2006-2011 was developed, the vector control component has remained relatively weak. The strategy endorses the distribution of long-lasting insecticidal nets (LLINs) as the frontline intervention with other interventions recommended only when technical and institutional capacity is available. In 2006, a draft integrated vector management (IVM) strategic plan 2007-2012 was developed but never implemented, resulting in minimal coordination, implementation and coverage of malaria vector control tools including their inherent impact. To address this challenge, the vector control team of the National Malaria Control Programme (NMCP) is being strengthened. With the objective of building national capacity and technical collaboration for effective implementation of the IVM strategy, a national malaria vector control conference was held from 15-17th October 2012 in Juba. A range of NMCP partners, state ministries, acadaemia, private sector, national and international non-governmental organizations, including regional and global policymakers attended the meeting. The conference represented a major milestone and made recommendations revolving around the five key elements of the IVM approach. The meeting endorsed that vector control efforts in RSS be augmented with other interventions within the confines of the IVM strategy as a national approach, with strong adherence to its key elements. PMID:23394124

Chanda, Emmanuel; Doggale, Constantino; Pasquale, Harriet; Azairwe, Robert; Baba, Samson; Mnzava, Abraham

2013-02-08

56

Vector approximation method with parameter adaptation and torque control of CSI-fed induction motor  

Microsoft Academic Search

The concept of the vector approximation method for CSI-fed induction motors consists of vector control and the shaping of a stator current wave. Vector approximation means that a desirable space current vector is approximated by two realizable current vectors which have only six directions, and by DC link current control. The main purpose of the vector approximation method is not

Kozo Ide; Zhi-Guo Bai; Zi-Jiang Yang; Teruo Tsuji

1995-01-01

57

Experimental Study On Counter Flow Thrust Vector Control  

NASA Astrophysics Data System (ADS)

Counter Flow Thrust Vectoring (CFTV) is possibly the most promising fluidic thrust vector control method for deflecting the exhaust thrust of a jet engine. CFTV works by generating a countercurrent shear layer in one side of a planar jet and hence by altering the transverse pressure gradient across the jet. Prediction and control of vector angle is the most important aspect in any thrust vectoring system. Experiments are conducted to obtain pressure distribution on the collar surface, which is used with a vacuum system to generate counter flow on one side of a rectangular (aspect ratio 4:1) jet. The exit Mach number of the ideally expanded jet considered here is 1.44. Gap height between the nozzle and collar surface is varied and vector angle for different mass flow rate has been obtained. The condition at which the jet attaches with the collar surface is found and compared with the predicted theoretical results.

Madruga, Maria S.; Das, Debopam; Strykowski, Paul J.

2000-11-01

58

Solid Rocket Booster Thrust Vector Control Subsystem Description.  

National Technical Information Service (NTIS)

Major Solid Rocket Booster-Thrust Vector Control (SRB-TVC) subsystem components and subcomponents used in the Space Transportation System (STS) are identified. Simplified schematics, detailed schematics, figures, photographs, and data are included to acqu...

J. Redmon

1983-01-01

59

Advances in vector control of ac motor drives — A review  

Microsoft Academic Search

This paper attempts to present a comprehensive review of the advances made in vector control or field orientation as applied\\u000a to high performanceac motor drives. Brief application survey, machine models ind-q representation, implementation issues with inverters and cycloconverters, parameter effects etc for both induction and synchronous\\u000a motor vector control are dealt with and sample results from studies on them are

A K Chattopadhyay

1997-01-01

60

Combination of laboratory research and remote sensing applications toward mitigation of trypanosomiasis in Africa  

Microsoft Academic Search

The need for a comprehensive bi-modal approach toward mitigation of trypanosomiasis in Africa, in both human and animal populations, is examined. Fundamental to such mitigation is the continuance of basic research at the molecular level, which may hold promise of a better understanding of the organism, Trypanosoma brucei, and consequently thereby identify potential controlling mechanisms. Equally important to ultimate mitigation

Hildred Sarah Rochon; Amber Randall; Deirdre Brekken; Marilyn Parsons

2002-01-01

61

Indirect vector control of an induction generator with LVRT capability  

Microsoft Academic Search

The paper deals with variable speed squirrel cage induction generator. The whole system is composed by a squirrel cage induction generator and a full power converter connected between generator and grid. The stator-side converter is controlled by means of an indirect vector control, which allows the system works without sensors requirement. The stator-side converter controls the torque of the generator

Jose Luis Dominguez-Garcia; Oriol Gomis-Bellmunt; Antoni Sudria-Andreu; Lluis Trilla-Romero

2011-01-01

62

Efficiency aspects of vector control applied to synchronous reluctance motors  

Microsoft Academic Search

Core losses in a synchronous reluctance machine are modelled. The empirical model obtained is used to implement a control scheme to compensate for equivalent core loss currents. This enables accurate control of the magnetising currents, hence torque. Efficiency over the base speed operating range of the machine is compared for two different vector control schemes. Methods of triplen series injection

John E. Fletcher; Barry W. Williams; Tim C. Green

1995-01-01

63

Design and test of electromechanical actuators for thrust vector control  

Microsoft Academic Search

New control mechanisms technologies are currently being explored to provide alternatives to hydraulic thrust vector control (TVC) actuation systems. For many years engineers have been encouraging the investigation of electromechanical actuators (EMA) to take the place of hydraulics for spacecraft control\\/gimballing systems. The rationale is to deliver a lighter, cleaner, safer, more easily maintained, as well as energy efficient space

J. R. Cowan; Rae Ann Weir

1993-01-01

64

Combining Countercurrent Shear Flow Control and Transverse Jets for Fluidic Thrust Vector Control  

Microsoft Academic Search

Countercurrent shear flow control has been established as an effective method for thrust vector control but has been challenged by hardware integration issues. Recent developments in fluidic thrust vector control have focused on nozzle interior methods that skew the throat of the nozzle using multiple transverse jets. The present work is motivated to combine these two flow control approaches to

Ignacio Echavarria Diaz-Guardamino; David Forliti

2007-01-01

65

Spray characterization of ULV sprayers typically used in vector control  

Technology Transfer Automated Retrieval System (TEKTRAN)

Numerous spray machines are used to apply products for the control of human disease vectors, such as mosquitoes and flies. However, the selection and setup of these machines significantly affect the level of control achieved during an application. The droplet spectra produced by nine different ULV...

66

The biology and control of malaria vectors in India  

Microsoft Academic Search

Despite considerable success of malaria control pro- gramme in the past, malaria still continues as a major public health problem. The malaria control in India relies mainly on indoor residual spraying of insecticides, which has become a formidable task due to widespread resistance in malaria vectors, particularly in Anopheles culicifacies, responsible for a majority of malaria cases in India. The

A. P. Dash; T. Adak; K. Raghavendra; O. P. Singh

2007-01-01

67

Chattering-Free Support Vector Regression Sliding Mode Control  

Microsoft Academic Search

According to an uncertain discrete system with input saturation, a new chattering free support vector regression sliding mode control (SVR-SMC) law based on Linear Matrix Inequalities (LMIs) is presented. The output of SVR is used for replacing sign function of the reaching law in traditional sliding mode control (SMC). An equivalent matrix is constructed for input saturation condition in the

Linsheng Li; Jianning Li

2008-01-01

68

Financial and economic aspects of environmental management for vector control.  

PubMed

Short term economic benefits of resource development generally carry more weight in political decision-making than the adverse health effects such projects may have in the medium and long term. This problem is particularly acute in the case of water resource development projects which can often promote the prevalence and incidence of certain vector-borne diseases such as schistosomiasis and malaria. And while the agricultural sector is usually strengthened by production increase resulting from water resource development, the health sector may ultimately have to pick up the bill for disease control programmes which become necessary as a consequence. At its sixth meeting in Geneva, the WHO/FAO/UNEP Panel of Experts on Environmental Management for Vector Control (PEEM) discussed the financial and economic aspects of environmental management, and its cost effectiveness as a vector control measure. Their report is now available and in this article, Robert Bos and Anne Mills discuss some of the key findings. PMID:15462944

Bos, R; Mills, A

1987-05-01

69

vectors  

NSDL National Science Digital Library

The word vector comes from the Latin term vehere, to carry. In Biology, a vector is an agent which carries disease, such as a mosquito carrying infected blood from one patient to the next. In physics, a vector is a quantity which has both a magnitude and a direction associated with it. The most commonly used example of vectors in everyday life is velocity. When you drive your car, your speedometer tells you the speed of your car, but it doesn't tell you where you are going. The combination of both where you are going and how fast you are going there is your car's velocity.

Joiner, David; The Shodor Education Foundation, Inc.

70

A vector oriented control for a magnetically levitated shaft  

SciTech Connect

Considering the nonlinear model of Active Magnetic Bearings, a new means of nonlinear control is presented which treats variables as rotating vectors in the control plane, specially the unbalance. It became easy to cancel out the effect of this perturbation in a rotating reference. Therefore, the rotor can rotate around any desired point, particularly the geometric center or the center of gravity. Simulations illustrate the efficacy of this control law.

De Miras, J.; Charara, A. [UTC, Compiegne (France)

1998-07-01

71

Sensorless vector controller for a synchronous reluctance motor  

Microsoft Academic Search

A new high-performance sensorless speed vector controller that implements the maximum torque per ampere control strategy for the inverter-driven synchronous reluctance machine is presented in this paper. It is based on a parameter-dependent technique for online estimation of rotor position and angular velocity at the control rate. The current ripple principle is used to estimate position. The estimates are fed

M. G. Jovanovic; R. E. Betz; D. Platt

1998-01-01

72

Novel space vector based current controllers for PWM-inverters  

Microsoft Academic Search

Two novel, simple control strategies for current-controlled pulse-width modulated (PWM) transistor inverters are presented. Both methods are based on the three-level hysteresis comparators which select appropriate inverter output voltage vectors via a switching electrically programmable read-only memory (EPROM) table. The first controller works with current components represented in a stationary coordinate system (AC components) and the second with components represented

M. P. Kazmierkowski; M. A. Dzieniakowski; W. Sulkowski

1991-01-01

73

Identifying Transmission Cycles at the Human-Animal Interface: The Role of Animal Reservoirs in Maintaining Gambiense Human African Trypanosomiasis  

PubMed Central

Many infections can be transmitted between animals and humans. The epidemiological roles of different species can vary from important reservoirs to dead-end hosts. Here, we present a method to identify transmission cycles in different combinations of species from field data. We used this method to synthesise epidemiological and ecological data from Bipindi, Cameroon, a historical focus of gambiense Human African Trypanosomiasis (HAT, sleeping sickness), a disease that has often been considered to be maintained mainly by humans. We estimated the basic reproduction number of gambiense HAT in Bipindi and evaluated the potential for transmission in the absence of human cases. We found that under the assumption of random mixing between vectors and hosts, gambiense HAT could not be maintained in this focus without the contribution of animals. This result remains robust under extensive sensitivity analysis. When using the distributions of species among habitats to estimate the amount of mixing between those species, we found indications for an independent transmission cycle in wild animals. Stochastic simulation of the system confirmed that unless vectors moved between species very rarely, reintroduction would usually occur shortly after elimination of the infection from human populations. This suggests that elimination strategies may have to be reconsidered as targeting human cases alone would be insufficient for control, and reintroduction from animal reservoirs would remain a threat. Our approach is broadly applicable and could reveal animal reservoirs critical to the control of other infectious diseases.

Funk, Sebastian; Nishiura, Hiroshi; Heesterbeek, Hans; Edmunds, W. John; Checchi, Francesco

2013-01-01

74

The impact of host species and vector control measures on the fitness of African malaria vectors.  

PubMed

Many malaria vector mosquitoes in Africa have an extreme preference for feeding on humans. This specialization allows them to sustain much higher levels of transmission than elsewhere, but there is little understanding of the evolutionary forces that drive this behaviour. In Tanzania, we used a semi-field system to test whether the well-documented preferences of the vectors, Anopheles arabiensis and Anopheles gambiae sensu stricto (s.s.) for cattle and humans, respectively, are predicted by the fitness they obtain from host-seeking on these species relative to other available hosts. Mosquito fitness was contrasted, when humans were fully exposed and when they were protected by a typical bednet. The fitness of both vectors varied between host species. The predicted relationship between host preference and fitness was confirmed in An. arabiensis, but not in An. gambiae s.s., whose fitness was similar on humans and other mammals. Use of typical, imperfect bednets generated only minor reductions in An. gambiae s.s. feeding success and fitness on humans, but was predicted to generate a significant reduction in the lifetime reproductive success of An. arabiensis on humans relative to cows. This supports the hypothesis that such human-protective measures could additionally benefit malaria control by increasing selection for zoophily in vectors. PMID:23303548

Lyimo, Issa N; Haydon, Daniel T; Russell, Tanya L; Mbina, Kasian F; Daraja, Ally A; Mbehela, Edgar M; Reeve, Richard; Ferguson, Heather M

2013-01-08

75

Vector disparity sensor with vergence control for active vision systems.  

PubMed

This paper presents an architecture for computing vector disparity for active vision systems as used on robotics applications. The control of the vergence angle of a binocular system allows us to efficiently explore dynamic environments, but requires a generalization of the disparity computation with respect to a static camera setup, where the disparity is strictly 1-D after the image rectification. The interaction between vision and motor control allows us to develop an active sensor that achieves high accuracy of the disparity computation around the fixation point, and fast reaction time for the vergence control. In this contribution, we address the development of a real-time architecture for vector disparity computation using an FPGA device. We implement the disparity unit and the control module for vergence, version, and tilt to determine the fixation point. In addition, two on-chip different alternatives for the vector disparity engines are discussed based on the luminance (gradient-based) and phase information of the binocular images. The multiscale versions of these engines are able to estimate the vector disparity up to 32 fps on VGA resolution images with very good accuracy as shown using benchmark sequences with known ground-truth. The performances in terms of frame-rate, resource utilization, and accuracy of the presented approaches are discussed. On the basis of these results, our study indicates that the gradient-based approach leads to the best trade-off choice for the integration with the active vision system. PMID:22438737

Barranco, Francisco; Diaz, Javier; Gibaldi, Agostino; Sabatini, Silvio P; Ros, Eduardo

2012-02-09

76

Imported human African trypanosomiasis in Europe, 2005-2009.  

PubMed

Physicians in Europe are likely to see more African trypanosomiasis cases because of the increasing popularity of travel to Africa. In this paper the literature on imported cases in Europe, since 2005 is reviewed. Because of the high mortality risk associated with acute Rhodesian trypanosomiasis, travellers should be informed about preventive measures and the early disease manifestations. PMID:19758542

Gautret, P; Clerinx, J; Caumes, E; Simon, F; Jensenius, M; Loutan, L; Schlagenhauf, P; Castelli, F; Freedman, D; Miller, A; Bronner, U; Parola, P

2009-09-10

77

Vectors  

NSDL National Science Digital Library

This web page introduces vectors as an extension of numbers having both magnitude and direction. The initial motivation is to describe velocity but the material includes a general discussion of vector algebra and an application to forces for the inclined plane. The page contains links to a related lesson plan and further opportunities to explore vectors. This is part of the extensive web site "From Stargazers to Starships", that uses space exploration and space science to introduce topics in physics and astronomy. Translations in Spanish and French are available.

Stern, David

2006-07-16

78

American trypanosomiasis (Chagas' disease) in the Caribbean.  

PubMed

Chagas' disease (American trypanosomiasis) is endemic in nearly all Central and South American countries facing the Caribbean basin. Since 1960, reports from the islands of Aruba, Curaçao, Jamaica, and Trinidad have confirmed the presence of Trypanosoma cruzi, blood-sucking triatomine bugs, and wild animals infected with the parasite. It was also established that T. cruzi, triatomine bugs, infected wild animal reservoirs, and people with a positive serologic test for T. cruzi antibodies are to be found in Belize, the last country in Central America once thought to be free of Chagas' disease. PMID:96895

Petana, W B

1978-01-01

79

SPATIAL EXPRESSIONS OF SLEEPING SICKNESS IN IVORY COAST AND GUINEA CONAKRY REMOTE SENSING AND SPATIAL ANALYSIS CONTRIBUTIONS TO MAP HUMAN AFRICAN TRYPANOSOMIASIS RISK AREA  

Microsoft Academic Search

At the end of 19th century in western Africa sleeping sickness - Human African Trypanosomiasis - was responsible for a lot of death in an entire state of complete Disorganisation caused by foreign political intervention. A very large movement of important population modified histori- cal natural equilibrium and humans were in active contact with the disease's vector, the Tse- Tse

Dominique Laffly; Pascal Handschumacher

80

Insecticide Control of Vector-Borne Diseases: When Is Insecticide Resistance a Problem?  

Microsoft Academic Search

Many of the most dangerous human diseases are transmitted by insect vectors. After decades of repeated insecticide use, all of these vector species have demonstrated the capacity to evolve resistance to insecticides. Insecticide resistance is generally considered to undermine control of vector-transmitted diseases because it increases the number of vectors that survive the insecticide treatment. Disease control failure, however, need

Ana Rivero; Julien Vézilier; Mylène Weill; Andrew F. Read; Sylvain Gandon

2010-01-01

81

Performance enhancement of vector controlled drive with rotor flux based MRAS rotor resistance estimator  

Microsoft Academic Search

Vector control schemes are increasingly used in induction motor drive systems to obtain high performance. Vector Control transforms the control of an induction motor to that of a separately excited dc motor by creating independent channels for flux and torque control. The successful implementation of the vector control scheme requires the knowledge of the instantaneous position of rotor flux which

M. Nandhini Gayathri; S. Himavathi; R. Sankaran

2012-01-01

82

A review of the control of Simulium vectors of onchocerciasis  

PubMed Central

The purpose of this paper is to bring together all the available information concerning the control of Simulium vectors of onchocerciasis in Africa and Central and South America. Some of the larger control schemes are described in detail. Insecticidal formulations, rates of dosage, and methods of application are given when available, and costs per square mile (or square kilometre) are quoted where possible as a guide to future operations. The efficacy of ground application (larviciding) as compared with aerial application (larviciding and adulticiding) is discussed and it is concluded that ground larviciding is likely to achieve the best results, at less cost, in onchocercal foci where the vectors usually breed in small, densely wooded streams. Data in connexion with fly densities, prior and subsequent to control schemes, are quoted when available.

McMahon, J. P.

1967-01-01

83

Controlling Compressor Vane Flow Vectoring Angles at Transonic Speeds  

NASA Astrophysics Data System (ADS)

The ability to control flow separation angles from compressor inlet guide vanes with a Coanda-type actuator is demonstrated using both wind tunnel experiments and finite element simulations. Vectoring angles up to 40 degrees from the uncontrolled baseline state were measured with helium schlieren visualization at transonic Mach numbers ranging from 0.1 to 0.6, and with airfoil chord Reynolds numbers ranging from 89,000 to 710,000. The magnitude of the vectoring angle is shown to depend upon the geometry of the trailing edge, and actuator slot size, and the momentum flux coefficient. Under certain conditions the blowing has no effect on the vectoring angle indicating that the Coanda effect is not present. DNS simulations with the finite element method investigated the effects of geometry changes and external flow. Continuous control of the vectoring angle is demonstrated, which has important implications for application to rotating machinery. The technique is shown to reduce the stall flow coefficient by 15 percent in an axial flow compressor.

Munson, Matthew; Rempfer, Dietmar; Williams, David; Acharya, Mukund

2003-11-01

84

Nonlinear robust control of a vector-controlled synchronous reluctance machine  

Microsoft Academic Search

This paper presents the implementation of Slotine's approach of sliding mode control for position control of a vector-controlled synchronous reluctance machine. A comparison is undertaken between the performance of a fixed gain controller and two sliding mode controllers for both the regulator and servo cases. Invariant performance is obtained using Slotine's approach of sliding mode control compared to a fixed

Thanaa Sharaf-Eldin; Matthew W. Dunnigan; John Edward Fletcher; Barry W. Williams

1999-01-01

85

Epidemiological impact of vector control. II. Changes in ocular onchocerciasis.  

PubMed

The impact of 10-11 years of successful vector control on ocular onchocerciasis was evaluated in the population of 13 villages in the central part of the Onchocerciasis Control Programme area. The prevalence of ocular microfilariae was found to have reduced remarkably and loads over 20 microfilariae in the anterior chamber of the eye or the cornea which was rampant before the start of vector control, were rare. Whilst limited change in the age specific prevalence of lesions of the posterior segment of the eye was recorded, significant reduction in the prevalence of lesions of the anterior segment of the eye was found. The small decrease in the age specific prevalence of lesions of the posterior segment of the eye was partly explained by a reduced occurrence of the type of lesions of the anterior segment of the eye which previously obstructed the effective view of the fundus during examination. The prevalence of blindness was found to have reduced by 40% and onchocercal blindness was no longer found below the age of 20 years. It was concluded that 10-11 years of successful vector control has effectively reduced the incidence of onchocercal eye lesions, the deterioration of the existing eye lesions and the risk of developing an onchocercal eye lesion as well as going blind to virtually nil. PMID:2378201

Dadzie, K Y; Remme, J; De Sole, G

1990-01-01

86

[Diagnosis of human African trypanosomiasis in 2001].  

PubMed

Human African trypanosomiasis is characterized by a non-specific clinical presentation with no consistent, pathognomonic manifestations. However definite diagnosis is necessary to avoid unnecessary therapeutic risks with toxic drugs. Further complicating this situation is the frequent need to achieve field diagnosis in remote locations with limited facilities. Serological tests such as CATT (card agglutination trypanosomiasis test) are useful for initial population screening to identify suspects but are not sufficiently reliable for definitive diagnosis since the variations in sensitivity and specificity have been observed between countries and disease pockets. Parasitological examination is still the only method of definitive diagnosis. Thresholds of trypanosome detection differ from one technique to another, i.e., 10,000 trypanosomes per millilitre (T/ml) for fresh blood smears, 5,000 T/ml for thick drop specimens stained with Giemsa, 500 T/ml for centrifugation in capillary tubes, less than 500 T/ml for the QBC test, and 100 T/ml for the ion exchange minicolumn system. The possibility that the QBC test and minicolumn anion exchange system may go out of production could pose a serious problem for field diagnosis. Decisional algorithms are being developed to optimize use of remaining techniques. PMID:11803824

Louis, F J; Buscher, P; Lejon, V

2001-01-01

87

Adaptive support vector regression for UAV flight control.  

PubMed

This paper explores an application of support vector regression for adaptive control of an unmanned aerial vehicle (UAV). Unlike neural networks, support vector regression (SVR) generates global solutions, because SVR basically solves quadratic programming (QP) problems. With this advantage, the input-output feedback-linearized inverse dynamic model and the compensation term for the inversion error are identified off-line, which we call I-SVR (inversion SVR) and C-SVR (compensation SVR), respectively. In order to compensate for the inversion error and the unexpected uncertainty, an online adaptation algorithm for the C-SVR is proposed. Then, the stability of the overall error dynamics is analyzed by the uniformly ultimately bounded property in the nonlinear system theory. In order to validate the effectiveness of the proposed adaptive controller, numerical simulations are performed on the UAV model. PMID:20970303

Shin, Jongho; Jin Kim, H; Kim, Youdan

2010-09-29

88

[Malaria vector control in Cameroon: past, present, future. Reflections].  

PubMed

During the fifties, large scale malaria vector control projects based upon house spraying were implemented in Southern and Northern parts of Cameroon in line of malaria eradication concept. In the South, the pilot zone of Yaounde gathered about 150,000 inhabitants, in the forest area. First operations started in 1953 but the programme became actually operational in 1956. It was divided in two parts: the western part was treated with DDT, while the eastern one was treated with dieldrin. At the same time, the whole forested area was also treated with dieldrin until 1960. Yaounde itself was not treated because it was free of anopheles and malaria. House spraying in the pilot area of Yaounde was a complete success and plasmodic index dropped below 1%. The same success was observed in most of the southern treated areas. Unfortunatly dieldrin resistance of An. gambiae hampered this programme which stopped in 1960. The northem pilot project dealt with some 250,000 inhabitants around Maroua, in a savanna area. To avoid dieldrin resistance observed in 1956, DDT was selected and house spraying started in 1959. From a strictly operational point of view, the campaign was considered as a success. But after two years, it was noticed that plasmodic index remained still around the same value of 35% and the programme stopped. It was thus stated that according to available techniques it was not possible to reach the ultimate goal of eradication even when chemoprophylaxis (chloroquin + pyrimethamin) was added. The comparison between south (= success) and north (= failure) was very interesting as it underlined the big differences between epidemiological faces, an unaccepted concept at that time. Now ecological and epidemiological diversity is the well acknowledged. It also underlined the need of diversity of strategies according to the epidemiology of the disease and the ecology of its vector Vector control was then stopped for a while. In the eighties, Primary Health Care was promoted and malaria control shifted from vector to parasite control, vector control remaining as a prevention method. But chemioresistance of Plasmodium falciparum appeared and. quickly spread, at different levels, across the country. A new emphasis was therefore given to vector control thank to the newly developed technique of insecticide impregnated mosquito nets. Two kinds of studies were undertaken: - what people were actually doing in term of mosquito control at family level, the main reason and the costs as well as current use of mosquito nets - the efficacy of pyrethroid treated mosquito nets (IMN) in different areas of southern forested area against different malaria vectors: An. gambiae, An. nili, An. moucheti. It thus clearly appeared that IMN were very successful in sharply reducing malaria transmission aAd morbidity. But its promotion is limited by the current poor use of mosquito nets in Yaoundé (1 mosquito net for 27 "beds") while in Douala, where IMN are largely used against the bite of the huge population of Culex. quinquefasciatus, the implementation of the first riational centre for impregnation of mosquito net was a great success, as long as it was headed by a motivated and skill manager Impregnated mosquito nets appear thus as a tool of great efficacy but their sustainability is still matter of concern and promotional campaigns must be developed involving private and public, political and scientific spheres as well as the general population who should be encouraged to become partners and even actors of vector and malaria control at their household level. PMID:16579079

Carnevale, P; Mouchet, J

2001-07-01

89

Development of embroidery machine vector control speed regulation system based on DSP  

Microsoft Academic Search

Based on the rotor field oriented control principle and space vector PWM technology, a vector control speed regulation algorithm applied to embroidery machines is developed based on DSP. Combined with the theoretical analysis, a kind of Anti-Windup PI controller is adopted based on output feedback calculations, and a discrete simulation model of the vector control speed regulation system is built

Yong-yang Li; Guang-zhong Cao; Hong Qiu; J. F. Pan; Chong-chong Yang

2011-01-01

90

A Research Agenda for Malaria Eradication: Vector Control  

PubMed Central

Different challenges are presented by the variety of malaria transmission environments present in the world today. In each setting, improved control for reduction of morbidity is a necessary first step towards the long-range goal of malaria eradication and a priority for regions where the disease burden is high. For many geographic areas where transmission rates are low to moderate, sustained and well-managed application of currently available tools may be sufficient to achieve local elimination. The research needs for these areas will be to sustain and perhaps improve the effectiveness of currently available tools. For other low-to-moderate transmission regions, notably areas where the vectors exhibit behaviours such as outdoor feeding and resting that are not well targeted by current strategies, new interventions that target predictable features of the biology/ecologies of the local vectors will be required. To achieve elimination in areas where high levels of transmission are sustained by very efficient vector species, radically new interventions that significantly reduce the vectorial capacity of wild populations will be needed. Ideally, such interventions should be implemented with a one-time application with a long-lasting impact, such as genetic modification of the vectorial capacity of the wild vector population.

2011-01-01

91

Human African Trypanosomiasis in South Sudan: How Can We Prevent a New Epidemic?  

Microsoft Academic Search

Human African trypanosomiasis (HAT) has been a major public health problem in South Sudan for the last century. Recurrent outbreaks with a repetitive pattern of responding-scaling down activities have been observed. Control measures for outbreak response were reduced when the prevalence decreased and\\/or socio-political crisis erupted, leading to a new increase in the number of cases. This paper aims to

José A. Ruiz-Postigo; José R. Franco; Mounir Lado; Pere P. Simarro

2012-01-01

92

[Distribution and spread of human African trypanosomiasis: value of genetic identification of the trypanosomes].  

PubMed

Numerous factors extrinsic to trypanosome populations have been implicated in the distribution and spread of human African trypanosomiasis (HAT), but quantification of these factors has proven difficult. An easier method of monitoring HAT consists of tracking parasites by genetic identification of trypanosomes in hosts and vectors. This method requires distinction between Trypanosoma brucei rhodesiense and Trypanosoma brucei gambiense followed by determination of the genotype of each subspecies in the host and vector. The role of vertebrate hosts in the distribution and spread of HAT has been confirmed by genetic identification of trypanosomes. Despite the ever-improving performance of biomolecular techniques, identification must be carried out on natural populations actually circulating in the biological fluids of the host and vector. This precaution is necessary to rule out the biasing effect of in vivo or in vitro isolation of trypanosomes. PMID:11803837

Truc, P; Cuny, G

2001-01-01

93

[Chagas disease (American trypanosomiasis) in France].  

PubMed

Chagas disease is an anthropozoonotic infection caused by Trypanosoma cruzi, transmitted by a hematophagous triatomine insect vector belonging to the Reduviidae family, while taking a blood meal. There is a large reservoir of wild and domestic mammals. Human contamination may come via vectorial, transplacental, and digestive routes, blood transfusion, organ or tissue transplantation, and by accident. The disease has two phases. The acute phase, oligosymptomatic, is frequently undiagnosed. It is followed by a chronic phase. Most of the infected patients remain asymptomatic all life-long. But 10 or 25 years later, one third of infected patients present with cardiac or digestive complications. Chagas disease is endemic in Latin America, from Mexico to Argentina. In French Guyana, the prevalence of the infection was estimated at 0.25% and 0.5% (from 500 to 1000 infected patients) on blood samples collected from 1992 to 1998. In 2000 and 2009, 192 cases were diagnosed. In this district, there is no established domestic vector and the transmission risk is low. The vector is very easily found in forest habitats and even in the peridomestic persistent forest, with an infection rate of 46 to 86%. Vectorial eradication is impossible. Fighting against Chagas disease in French Guyana relies more on individual protection, control of blood transfusion, prevention of mother-to-child transmission, diagnosis, and treatment of infected patients than on vectorial control. PMID:22591727

Salamanca-Dejour, D; Blanchet, D; Aznar, C; La Ruche, G; Jeannel, D; Gastellu-Etchegorry, M

2012-05-14

94

Predators indirectly control vector- borne disease: linking predator prey and host -pathogen models  

Microsoft Academic Search

Pathogens transmitted by arthropod vectors are common in human populations, agricultural systems and natural communities. Transmission of these vector-borne pathogens depends on the population dynamics of the vector species as well as its interactions with other species within the community. In particular, predation may be sufficient to control pathogen prevalence indirectly via the vector. To examine the indirect effect of

Sean M. Moore; Elizabeth T. Borer; Parviez R. Hosseini

2009-01-01

95

Direct torque control, induction motor vector control without an encoder  

Microsoft Academic Search

The basic evolution of direct torque control from other drive types is explained. Qualitative comparisons with other drives are included. The basic concepts behind direct torque control are clarified. An explanation of direct self control and the field-orientation concepts implemented in the adaptive motor model block is presented. The reliance of the control method on fast processing techniques is stressed.

James N. Nash

1997-01-01

96

[Control Program of Chagas disease in São Paulo, Brazil: the control and surveillance of vector transmission].  

PubMed

The control of the vectors of Chagas' disease in the State of Sao Paulo are discussed, mainly those activities that led to the elimination of Triatoma infestans. Secondary factors that helped the control such as rural exodus are also analyzed. The article shows that since 1965 the control became a campaign with different phases due to the epidemiological situation, the acquired knowledge and the entomological surveillance. After 25 years of work, the elimination of all the focus of Triatoma infestans was finally reached and the campaign was ended. However, due to the possibility of reintroduction of the vector in rural areas by passive transportation besides the presence of secondary vectors (Triatoma sordida and Panstrongylus megistus) in several localities, the vector control activities were not interrupted and the surveillance is continuous. PMID:21584361

Silva, Eduardo Olavo da Rocha e; Rodrigues, Vera Lúcia Cortiço Corrêa; Silva, Rubens Antonio da; Wanderley, Dalva Marli Valério

2011-01-01

97

DSP Based Implementation of Hybrid Speed Controller for Vector Controlled Permanent Magnet Synchronous Motor Drive  

Microsoft Academic Search

This paper presents a digital signal processor (DSP) based implementation of a hybrid of fuzzy logic controller (FLC) and proportional-integral (PI) speed controller for vector controlled (VC) permanent magnet synchronous motor (PMSM) drive. The fuzzy membership function is used for the hybrid combination of these two FLC and PI speed controllers in such a way that during the time of

B. Singh; S. Dwivedi

2006-01-01

98

Cellular Immune Mechanisms in Malaria and African Trypanosomiasis.  

National Technical Information Service (NTIS)

The cell-mediated immune defense mechanisms responsible for host resistance to malaria and trypanosomiasis are poorly understood. The authors therefore examined peripheral blood mononuclear cells from Thai adults naturally infected with malaria in order t...

R. P. MacDermott

1978-01-01

99

Vector-Borne Diseases: Understanding the Environmental, Human Health, and Ecological Connections. Workshop Summary. Held in Fort Collins, Colorado on June 19-20, 2007.  

National Technical Information Service (NTIS)

Vector-borne diseases such as malaria, dengue, yellow fever, plague, trypanosomiasis, and leishmaniasis have been major causes of morbidity and mortality throughout human history. During the early to mid-20th century, the vectors for yellow fever, malaria...

D. A. Relman E. R. Choffnes M. A. Hamburg P. F. Sparling S. M. Lemon

2008-01-01

100

The Burden of Human African Trypanosomiasis  

PubMed Central

Human African trypanosomiasis (HAT, or sleeping sickness) is a protozoan parasitic infection caused by Trypanosoma brucei rhodesiense or Trypanosoma brucei gambiense. These are neglected tropical diseases, and T.b. rhodesiense HAT is a zoonosis. We review current knowledge on the burden of HAT in sub-Saharan Africa, with an emphasis on the disability-adjusted life year (DALY), data sources, and methodological issues relating to the use of this metric for assessing the burden of this disease. We highlight areas where data are lacking to properly quantify the impact of these diseases, mainly relating to quantifying under-reporting and disability associated with infection, and challenge the HAT research community to tackle the neglect in data gathering to enable better evidence-based assessments of burden using DALYs or other appropriate measures.

Fevre, Eric M.; Wissmann, Beatrix v.; Welburn, Susan C.; Lutumba, Pascal

2008-01-01

101

[Human African trypanosomiasis: present and future treatment ].  

PubMed

During his life General Lapeyssonnie coped with the hazards linked to the therapeutics of the human African trypanosomiasis (HAT), sometimes with passion and disappointment, sometimes with revolt and hope. Because of a lack of political and financial concern during the past decades, a real global policy against the disease and a drug research against HAT didn't emerge. Today, some changes seem to take place. They are the result of the frightening spread of the disease and of the moral obligation that forces pharmaceutical companies to intervene. Drug research needs to be increased. New drugs should present no toxicity and should be able to cross through the blood-brain barrier with efficient cerebrospinal fluid concentrations. Moreover, new drugs should be easy to synthesize, easy to use and at a low cost. Today, megazol is the only one product in preclinical development, which seems to reach each of these goals. PMID:12696372

Dumas, M; Bouteille, B

2002-12-01

102

Neuro-vector-based electrical machine driver combining a neural plant identifier and a conventional vector controller  

Microsoft Academic Search

One of the most important problems, for a machine control process is the system identification. To identify varying parameters which are dependent from other system's parameters (speed, voltage and currents, etc.), one must have an adaptive control system. Synchronous machines conventional vector control's implementation using PID controllers have been recently proposed presenting the best actual solution. It supposes an appropriated

Kurosh Madani; Gilles Mercier; Mohammad Dinarvand; Jean-Charles Depecker

1999-01-01

103

Stator flux based space-vector modulation and closed loop control of the stator flux vector in overmodulation into six-step mode  

Microsoft Academic Search

This paper presents closed loop control of stator flux vector in a wide operating range that can be used in torque control. A predictive control achieves zero phase error at constant switching frequency. Space vector modulation based on stator flux error vector is used to achieve control of stator flux over the entire range including overmodulation and six-step. During dynamics

Anshuman Tripathi; Ashwin M. Khambadkone; Sanjib K. Panda

2004-01-01

104

Sensorless vector control system of permanent magnet synchronous motors based on adaptive and fuzzy control  

Microsoft Academic Search

This paper presents a sensorless vector control system of permanent magnet synchronous motor based on adaptive and fuzzy control. The proposed system is constructed in an arbitrary rotating reference frame and the speed estimator is based on the adaptive theory using the current error. Additionally, the fuzzy control theory is applied to this system for improving the stability and dynamic

Hua Lin; Shuo Chen; Jihua Yao; Mineo Tsuji

2008-01-01

105

DSP Based Implementation of Fuzzy Precompensated PI Speed Controller for Vector Controlled PMSM Drive  

Microsoft Academic Search

This paper deals with the analysis and hardware implementation of a fuzzy precompensated proportional-integral (FPPI) speed controller for vector controlled (VC) permanent magnet synchronous motor (PMSM) drive using a digital signal processor. The power circuit of the PMSM drive consists of insulated gate bipolar transistor (IGBT) based voltage source inverter (VSI) and the gate driver circuit. The hardware of control

Bhim Singh; Sanjeet Dwivedi

2006-01-01

106

Experimental Evaluation of Design Variables for Two-Dimensional Confined Jet Thrust Vector Control Nozzles.  

National Technical Information Service (NTIS)

An experimental study of the axial and vectoring performance of two - dimensional (2-D) confined jet thrust vector control (CJTVC) nozzles was performed. The effects of adding secondary injection ports and changing exit height and secondary injection port...

T. M. Hawkes

1991-01-01

107

Silica nanoparticle: a potential new insecticide for mosquito vector control.  

PubMed

Presently, there is a need for increased efforts to develop newer and effective methods to control mosquito vectors as the existing chemical and biological methods are not as effective as in earlier period owing to different technical and operational reasons. The use of nanomaterial products in various sectors of science including health increased during the last decade. We tested three types of nanosilica, namely lipophilic, hydrophilic and hydrophobic, to assess their larvicidal, pupicidal and growth inhibitor properties and also their influence on oviposition behaviour (attraction/deterrence) of mosquito species that transmit human diseases, namely malaria (Anopheles), yellow fever, chickungunya and dengue (Aedes), lymphatic filariasis and encephalitis (Culex and Aedes). Application of hydrophobic nanosilica at 112.5 ppm was found effective against mosquito species tested. The larvicidal effect of hydrophobic nanosilica on mosquito species tested was in the order of Anopheles stephensi > Aedes aegypti > Culex quinquefasciatus, and the pupicidal effect was in the order of A. stephensi > C. quinquefasciatus > Ae. aegypti. Results of combined treatment of hydrophobic nanosilica with temephos in larvicidal test indicated independent toxic action without any additive effect. This is probably the first report that demonstrated that nanoparticles particularly nanosilica could be used in mosquito vector control. PMID:22565400

Barik, Tapan K; Kamaraju, Raghavendra; Gowswami, Arunava

2012-05-08

108

Variable gain PI controller design for speed control and rotor resistance estimation of an indirect vector controlled induction machine drive  

Microsoft Academic Search

This paper presents an original variable gain PI (VGPI) controller for speed control and rotor resistance estimation of an indirect vector controlled (IVC) induction motor drive. First, a VGPI speed controller is designed. Its simulated performances in speed control and rotor resistance estimation are compared to those of a classical PI controller. Simulation of the IVC induction motor drive using

A. Miloudi; A. Draou

2002-01-01

109

Vector control of hybrid stepping motor position servo system using neural network control  

Microsoft Academic Search

To achieve fast four-quadrant operation and smooth starting and acceleration, vector control is used in the design of the stepping motor servo system drive. The control performance of the stepping motor servo system drive still influenced by the uncertainties, such as external load disturbance, nonlinearity and motor parameter variations. Neural network is used as a supervisor to deal with nonlinearity

Kefsi Laid; Xu Dianguo; Shi Jingzhuo

2001-01-01

110

Application of H? Control in Rudder\\/Flap Vector Robust Control for Ship Course  

Microsoft Academic Search

For the parameter uncertainty and the disturbance randomicity that exist in ship course motion, the robust controller of ship course is designed on the base of rudder\\/flap vector control. The system uncertainty is analyzed, and the choice of weighting functions is discussed chiefly. For the sea wave operating on the ship, its energy-concentrating frequency varies as the encountering angle. For

Liu Sheng; Fang Liang; Li Jia-lai

2007-01-01

111

DSP based implementation of Sliding Mode Speed Controller for Vector Controlled Permanent Magnet Synchronous Motor drive  

Microsoft Academic Search

The paper deals with the performance analysis and hardware implementation of a sliding mode (SM) speed controller for vector controlled (VC) permanent magnet synchronous motor (PMSM) drive using a digital signal processor (DSP). The power circuit of the PMSM drive system consists of insulated gate bipolar transistor (IGBT) based voltage source inverter (VSI) and the gate driver circuit. The hardware

Bhim Singh; Sanjeet Dwivedi

2006-01-01

112

Static Compaction Techniques to Control Scan Vector Power Dissipation  

Microsoft Academic Search

Excessive switching activity during scan testing can cause average power dissipation and peak power during test to be much higher than during normal operation. This can cause problems both with heat dissipation and with current spikes. Compacting scan vectors greatly increases the power dissipation for the vectors (generally the power becomes several times greater). The compacted scan vectors often can

Ranganathan Sankaralingam; Rama Rao Oruganti; Nur A. Touba

2000-01-01

113

Emergence and prevalence of human vector-borne diseases in sink vector populations.  

PubMed

Vector-borne diseases represent a major public health concern in most tropical and subtropical areas, and an emerging threat for more developed countries. Our understanding of the ecology, evolution and control of these diseases relies predominantly on theory and data on pathogen transmission in large self-sustaining 'source' populations of vectors representative of highly endemic areas. However, there are numerous places where environmental conditions are less favourable to vector populations, but where immigration allows them to persist. We built an epidemiological model to investigate the dynamics of six major human vector borne-diseases in such non self-sustaining 'sink' vector populations. The model was parameterized through a review of the literature, and we performed extensive sensitivity analysis to look at the emergence and prevalence of the pathogen that could be encountered in these populations. Despite the low vector abundance in typical sink populations, all six human diseases were able to spread in 15-55% of cases after accidental introduction. The rate of spread was much more strongly influenced by vector longevity, immigration and feeding rates, than by transmission and virulence of the pathogen. Prevalence in humans remained lower than 5% for dengue, leishmaniasis and Japanese encephalitis, but substantially higher for diseases with longer duration of infection; malaria and the American and African trypanosomiasis. Vector-related parameters were again the key factors, although their influence was lower than on pathogen emergence. Our results emphasize the need for ecology and evolution to be thought in the context of metapopulations made of a mosaic of sink and source habitats, and to design vector control program not only targeting areas of high vector density, but working at a larger spatial scale. PMID:22629337

Rascalou, Guilhem; Pontier, Dominique; Menu, Frédéric; Gourbière, Sébastien

2012-05-18

114

Trapping volume control in optical tweezers using cylindrical vector beams.  

PubMed

We present the result of an investigation into the optical trapping of spherical microparticles using laser beams with a spatially inhomogeneous polarization direction [cylindrical vector beams (CVBs)]. We perform three-dimensional tracking of the Brownian fluctuations in the position of a trapped particle and extract the trap spring constants. We characterize the trap geometry by the aspect ratio of spring constants in the directions transverse and parallel to the beam propagation direction and evaluate this figure of merit as a function of polarization angle. We show that the additional degree of freedom present in CVBs allows us to control the optical trap strength and geometry by adjusting only the polarization of the trapping beam. Experimental results are compared with a theoretical model of optical trapping using CVBs derived from electromagnetic scattering theory in the T-matrix framework. PMID:23282827

Skelton, S E; Sergides, M; Saija, R; Iatì, M A; Maragó, O M; Jones, P H

2013-01-01

115

Neuro-vector-based electrical machine driver combining a neural plant identifier and a conventional vector controller  

NASA Astrophysics Data System (ADS)

One of the most important problems, for a machine control process is the system identification. To identify varying parameters which are dependent from other system's parameters (speed, voltage and currents, etc.), one must have an adaptive control system. Synchronous machines conventional vector control's implementation using PID controllers have been recently proposed presenting the best actual solution. It supposes an appropriated model of the plant. But real plant's parameters vary and the P.I.D. controller is not suitable because of the parameters variation and non-linearity introduced by the machine's physical structure. In this paper, we present an on-line dynamic adaptive neural based vector control system identifying the motor's parameters of a synchronous machine. We present and discuss a DSP based real- time implementation of our adaptive neuro-controller. Simulation and experimental results validating our approach have been reported.

Madani, Kurosh; Mercier, Gilles; Dinarvand, Mohammad; Depecker, Jean-Charles

1999-03-01

116

Community involvement in dengue vector control: cluster randomised trial  

PubMed Central

Objective To assess the effectiveness of an integrated community based environmental management strategy to control Aedes aegypti, the vector of dengue, compared with a routine strategy. Design Cluster randomised trial. Setting Guantanamo, Cuba. Participants 32 circumscriptions (around 2000 inhabitants each). Interventions The circumscriptions were randomly allocated to control clusters (n=16) comprising routine Aedes control programme (entomological surveillance, source reduction, selective adulticiding, and health education) and to intervention clusters (n=16) comprising the routine Aedes control programme combined with a community based environmental management approach. Main outcome measures The primary outcome was levels of Aedes infestation: house index (number of houses positive for at least one container with immature stages of Ae aegypti per 100 inspected houses), Breteau index (number of containers positive for immature stages of Ae aegypti per 100 inspected houses), and the pupae per inhabitant statistic (number of Ae aegypti pupae per inhabitant). Results All clusters were subjected to the intended intervention; all completed the study protocol up to February 2006 and all were included in the analysis. At baseline the Aedes infestation levels were comparable between intervention and control clusters: house index 0.25% v 0.20%, pupae per inhabitant 0.44×10?3 v 0.29×10?3. At the end of the intervention these indices were significantly lower in the intervention clusters: rate ratio for house indices 0.49 (95% confidence interval 0.27 to 0.88) and rate ratio for pupae per inhabitant 0.27 (0.09 to 0.76). Conclusion A community based environmental management embedded in a routine control programme was effective at reducing levels of Aedes infestation. Trial registration Current Controlled Trials ISRCTN88405796.

2009-01-01

117

Control strategies for energy recovery from a flywheel using a vector controlled induction machine  

Microsoft Academic Search

This paper presents a novel control strategy for power smoothing in wind energy applications, especially those feeding a stand-alone load. The system is based on a vector controlled induction machine driving a flywheel and addresses the problem of regulating the DC-link system voltage against both input power surges\\/sags from a wind turbine or sudden changes in load demand. The control

R. Cardenas; R. Pena; G. Asher; J. Clare

2000-01-01

118

A compensated vector control scheme of a synchronous reluctance motor including saturation and iron losses  

Microsoft Academic Search

A compensated vector control algorithm for a synchronous reluctance motor (SRM) including saturation and iron losses is presented. It is shown that the current components that directly govern the torque production have been very well regulated by the proposed control scheme. The computer simulation and experimental results indicate a substantial improvement of torque performance for the vector-controlled SRM

L. Xu; J. Yao

1992-01-01

119

A compensated vector control scheme of a synchronous reluctance motor including saturation and iron losses  

Microsoft Academic Search

A compensated vector control algorithm for a synchronous reluctance motor including saturation and iron losses is presented. It is shown that the current components which directly govern the torque production are well regulated by the proposed control scheme. The comparison made by computer simulation indicates a substantial improvement of torque performance for the vector controlled synchronous reluctance motor

Longya Xu; Jiping Yao

1991-01-01

120

Sustainability of vector control strategies in the Gran Chaco Region: current challenges and possible approaches  

Microsoft Academic Search

Sustainability has become a focal point of the international agenda. At the heart of its range of distribution in the Gran Chaco Region, the elimination of Triatoma infestans has failed, even in areas subject to intensive professional vector control efforts. Chagas disease control programs traditionally have been composed of two divorced enti- ties: a vector control program in charge of

Ricardo E Gürtler

2009-01-01

121

Efficacy of local neem extracts for sustainable malaria vector control in an African village  

Microsoft Academic Search

BACKGROUND: Larval control of malaria vectors has been historically successful in reducing malaria transmission, but largely fell out of favour with the introduction of synthetic insecticides and bed nets. However, an integrated approach to malaria control, including larval control methods, continues to be the best chance for success, in view of insecticide resistance, the behavioural adaptation of the vectors to

Rebecca L Gianotti; Arne Bomblies; Mustafa Dafalla; Ibrahim Issa-Arzika; Jean-Bernard Duchemin; Elfatih AB Eltahir

2008-01-01

122

Plasmid vector with temperature-controlled gene expression  

SciTech Connect

In plasmid pBR327, a fragment 169 b.p. long including promotor p/sub 3/ of the bla gene has been deleted. The deletional derivative so obtained (pSP2) has been used to construct a recombinant plasmid bearing a fragment of phage lambda DNA with the p/sub R/ promotor and the gene of the temperature-sensitive repressor cI. It has been shown that the plasmid vector so constructed (pCE119) with promotor cR performs repressor-cI-controlled transcription of the bla gene, as a result of which induction for an hour at 42/sup 0/C leads to an almost 100-fold increase in the amount of product of the bla gene as compared with that at 32/sup 0/C. The possibility of the use of plasmid cPE119 for the expression of other genes has been demonstrated for the case of the semisynthetic ..beta..-galactosidase gene of E. coli. In this case, on induction of the cells with recombinant plasmid pCEZ12 for 3 hours at 42/sup 0/C, a 300-fold increase in the amount of active ..beta..-galactosidase, as compared with that at 32/sup 0/C, was observed. It is important to point out that under these conditions (at 42/sup 0/C), at least 99% of the cells containing the plasmid retain the phenotype lacZ/sup +/, which indicates the stability of the proposed vector system

Kravchenko, V.V.; Yamshchikov, V.F.; Pletnev, A.G.

1986-02-01

123

Prevalence of trypanosomiasis in cattle in south-west Zambia.  

PubMed

A trypanosomiasis survey was conducted in South-West Zambia. From a total of 3,346 cattle sampled 342 cattle showed a positive trypanosomiasis parasitaemia. During the survey trypanosome species and PCV values were also recorded. With simple statistical analysis populations with higher and lower prevalence rates were differentiated. The results indicated that the Kwando River Basin Tsetse Fly Belt and the Kafue River Basin Tsetse Fly Belt infested a larger area than originally assumed and that a link-up between both belts occurred or will occur in the near future. PMID:3400114

Corten, J J; ter Huurne, A A; Moorhouse, P D; de Rooij, R C

1988-05-01

124

Feedback control for counterflow thrust vectoring with a turbine engine: Experiment design and robust control design and implementation  

Microsoft Academic Search

Engineering research over the last few years has successfully demonstrated the potential of thrust vector control using counterflow at conditions up to Mach 2. Flow configurations that include the pitch vectoring of rectangular jets and multi-axis vector control in diamond and axisymmetric nozzle geometries have been studied. Although bistable (on-off) fluid-based control has been around for some time, the present

Delfim Zambujo Das Dores

2005-01-01

125

Integrated pest management and allocation of control efforts for vector-borne diseases  

USGS Publications Warehouse

Applications of various control methods were evaluated to determine how to integrate methods so as to minimize the number of human cases of vector-borne diseases. These diseases can be controlled by lowering the number of vector-human contacts (e.g., by pesticide applications or use of repellents), or by lowering the proportion of vectors infected with pathogens (e.g., by lowering or vaccinating reservoir host populations). Control methods should be combined in such a way as to most efficiently lower the probability of human encounter with an infected vector. Simulations using a simple probabilistic model of pathogen transmission suggest that the most efficient way to integrate different control methods is to combine methods that have the same effect (e.g., combine treatments that lower the vector population; or combine treatments that lower pathogen prevalence in vectors). Combining techniques that have different effects (e.g., a technique that lowers vector populations with a technique that lowers pathogen prevalence in vectors) will be less efficient than combining two techniques that both lower vector populations or combining two techniques that both lower pathogen prevalence, costs being the same. Costs of alternative control methods generally differ, so the efficiency of various combinations at lowering human contact with infected vectors should be estimated at available funding levels. Data should be collected from initial trials to improve the effects of subsequent interventions on the number of human cases.

Ginsberg, H. S.

2001-01-01

126

Design Three-phase Asynchronous Motor's Vector Control System Based on DSP  

Microsoft Academic Search

Better to meet the high performance AC speed adjustable speed control strategies and advanced control algorithms in the application of asynchronous motor, Introduced the hardware and software design of asynchronous motor control system development platform based on TMS320F2812.Discussed the vector control system for three-phase Asynchronous motor which use this platform as the control core, described the vector control principle and

Junyi Shen; Wenguang Luo; Chengwu Yang; Deliang Meng

2011-01-01

127

Modeling and vector control of planar magnetic levitator  

SciTech Connect

The authors designed and implemented a magnetically levitated stage with large planar motion capability. This planar magnetic levitator employs four novel permanent-magnet linear motors. Each motor generates vertical force for suspension against gravity, as well as horizontal force for drive. These linear levitation motors can be used as building blocks in the general class of multi-degree-of-freedom motion stages. In this paper, the authors discuss electromechanical modeling and real-time vector control of such a permanent-magnet levitator. They describe the dynamics in a dq frame introduced to decouple the forces acting on the magnetically levitated moving part, namely, the platen. A transformation similar to the Blondel-Park transformation is derived for commutation of the stator phase currents. The authors provide test results on step responses of the magnetically levitated stage. It shows 5-nm rms positioning noise in x and y, which demonstrates the applicability of such stages in the next-generation photolithography in semiconductor manufacturing.

Kim, W. [SatCon Technology Corp., Cambridge, MA (United States); Trumper, D.L.; Lang, J.H. [Massachusetts Inst. of Tech., Cambridge, MA (United States)

1998-11-01

128

The use of attractants and repellents in vector control  

PubMed Central

A great many stimuli—auditory, visual and chemical—attract or repel insects and some of these play an essential role in maintaining the life of the individual or perpetuating the species. The author examines the modes of action of attractants in nature, particularly in relation to blood feeding. The predominant mechanism of attraction to an odour source (e.g., in host finding) appears to be positive anemotaxis. Success in locating the source is influenced by wind conditions and by the visual acuity and field of view of the insect. The author considers the physical and chemical properties of materials that have been widely used as attractants and repellents and indicates the unsatisfactory nature of present theories to explain their action. Possible applications of attractants in vector control include their use in traps, baits and sprays, while repellents are mainly of value for personal protection. Increased understanding of the mechanism of action is likely to lead to the development of much more effective materials and to their wider application.

Hocking, B.

1963-01-01

129

An effective identification of rotor resistance for induction motor vector control  

Microsoft Academic Search

Nowadays, vector control induction motor have gained wide acceptance in high performance applications. Crucial to the success of the indirect vector control is the knowledge of the instantaneous position of the rotor flux. This requires a priori knowledge of rotor time constant which varies with rotor temperature. So, the variations of rotor circuit time constant can cause significant performance deterioration

M. Benhaddadi; K. Yazid; R. Khaldi

1997-01-01

130

Sensorless vector control of induction motor compensating the variation of rotor resistance  

Microsoft Academic Search

The authors describe a compensation method for the rotor resistance variation of induction machines in a speed sensorless vector control system using an MRAS (model reference adaptive system). In the case of rotor resistance variation, an analysis of the conventional speed sensorless vector control system using an MRAS is presented. and a compensation method for rotor resistance variation using fuzzy

Taeck-Kie Lee; Soon-Bong Cho; Dong-Seok Hyun

1992-01-01

131

Robust speed identification for speed-sensorless vector control of induction motors  

Microsoft Academic Search

This paper describes a new approach to estimating induction motor speed from measured terminal voltages and currents for speed-sensorless vector control. The proposed approach is based on observing the instantaneous reactive power of the motor. The estimated speed is used as feedback in an indirect vector control system. The described technique is very simple and robust to variations of motor

Fang-Zheng Peng; Tadashi Fukao

1994-01-01

132

A Control Method for Asynchronous Motor Based on Stator Current Vector Orientation  

Microsoft Academic Search

The stator flux model is different at high speed and low speed for the direct torque control (DTC), so the structure of DTC system is complex. Aiming at this issue, a new scheme of induction motor drive is proposed. The core idea is controlling the angle between the stator current vector and the rotor flux vector. It doesn't need the

Jiaquan Lin; Yi Zang; Jun Zhang; Xu Wang; Zongfu Liu

2006-01-01

133

Evaluation of Novel Insecticides for Control of Dengue Vector Aedes aegypti (Diptera: Culicidae)  

Microsoft Academic Search

Insecticides are one of the major tools for controlling vector populations and for reducing the transmission of human pathogens. However, there are few new insecticides being developed and marketed for vector control. Herein, we report on the toxicity of six novel insecticides to both adult and larval Aedes aegypti (L). and the toxicity of three novel insect growth regulators (IGRs)

Ayesa Paul; Laura C. Harrington; Jeffrey G. Scott

2006-01-01

134

FPGA based space vector modulated trigger controller for a frequency converter  

Microsoft Academic Search

This paper proposes FPGA based space vector modulated (SVM) trigger controller that may be applied to a frequency converter used for high speed electrical drives, speed control of AC motor, induction heating, fluorescent lighting, ballast, high frequency power supplies and so on. To generate space vector pulse width modulated trigger pulses for the converter pperipheral input-output and FPGA interfacing has

Preeti Agarwal; Anshul Agarwal; Vineeta Agarwal

2010-01-01

135

Artificial Lower Limb with Myoelectrical Control Based on Support Vector Machine  

Microsoft Academic Search

For the optional control to artificial lower limb and natural gait, an artificial limb model with myoelectrical control was presented, and the recognition method based on support vector machine was discussed. The electromyography signal after pretreating and wavelet packet analyzing was stored in company with the motion of lower limb. Then support vector machine was used to build a model

Peng Yang; Lingling Chen; Xin Guo; Xitai Wang; Lifeng Li

2006-01-01

136

Study and simulation of space vector PWM control of double-star induction motors  

Microsoft Academic Search

This paper deals with a comparison between different structures of double-star induction motors (DSIMs), controlled by space vector PWM. The modelling of the DSIM is made using an arbitrary shift angle between the two three-phase windings. A new transformation matrix is proposed to develop a suitable dynamic model and to elaborate the space vector PWM control strategy for different values

D. Hadiouche; H. Razik; A. Rezzoug

2000-01-01

137

Extension of PWM space vector technique for multilevel current-controlled voltage source inverters  

Microsoft Academic Search

The space vector technique is widely used to shape the inverter output currents. In order to improve the inverter performance, especially in high-voltage applications, multilevel inverters structures are utilized. The conventional space vector technique cannot be applied to control the multilevel inverter output currents. In this paper, a generalized method for controlling the output currents of this type of inverter

J. Mahdavi; A. Agah; A. M. Ranjbar; H. A. Toliyat

1999-01-01

138

Risk for Human African Trypanosomiasis, Central Africa, 2000-2009  

PubMed Central

Comprehensive georeference records for human African trypanosomiasis in Cameroon, Central African Republic, Chad, Congo, Equatorial Guinea, and Gabon were combined with human population layers to estimate a kernel-smoothed relative risk function. Five risk categories were mapped, and ?3.5 million persons were estimated to be at risk for this disease.

Cecchi, Giuliano; Franco, Jose R.; Paone, Massimo; Fevre, Eric M.; Diarra, Abdoulaye; Postigo, Jose Antonio Ruiz; Mattioli, Raffaele C.; Jannin, Jean G.

2011-01-01

139

[Human African trypanosomiasis, contributions of experimental models].  

PubMed

Melarsoprol has remained the chosen drug for the late-stage treatment of human African trypanosomiasis (HAT) due both to Trypanosoma brucei (T.b.) gambiense and T.b. rhodesiense; however, arsenical encephalopathies, which are often fatal, occur in 5-10% of the treated cases. To date, two major problems have not been solved. The first one is the precise diagnosis of early involvement of the central nervous system (CNS) which determines the therapeutics to be administered. The second one is linked to the lack of data on in vivo efficacy of products which are effective in vitro against trypanosomes. Answers have to be provided by experimental animal models of HAT. Such models would allow for better studies of the pathology and pathogenesis of the disease, as well as therapeutic trials of potentially effective new drugs or combinations. We have developed acute and chronic murine and sheep experimental animal models of HAT infected by T. b. brucei. Meningoencephalitis and neurological signs are relatively difficult to obtain in murine models and require artificial means, such as suramin treatment on day 21 after-infection. The chronic murine model has demonstrated CNS involvement with meningitis, followed by meningoencephalitis with progressive astrocytosis. The sheep model develops a disease with CNS complications and cerebrospinal fluid can be collected. In the sheep model, we have described anti-galactocerebrosides antibodies, which represent major components of myelin, which may indicate an autoimmune process in the CNS. We then described these antibodies in the cerebrospinal fluids and sera from patients at a late-stage of the disease. From a therapeutic point of view, we have cured mice or sheep with low doses of melarsoprol, or with the nitroimidazole derivatives Ro 15-0216 and megazol, alone or combined with suramin. Further studies of these nitroimidazole compounds, which could be proposed for human use, have to be carried out on a-primate model infected by T.b. gambiense. To our knowledge, this primate model is not available. This is why we have recently developed a T. b. gambiense primate model of HAT on Cercopithecus aethiops. PMID:9642464

Bouteille, B; Millet, P; Enanga, B; Mezui Me, J; Keita, M; Jauberteau, M O; Georges, A; Dumas, M

1998-01-01

140

A vector control of a grid-connected 3L-NPC-VSC with DFIG drives  

Microsoft Academic Search

This paper presents a vector control of grid-connected three-level neutral point clamped voltage source converter (3L-NPC-VSC) connecting doubly-fed induction generator (DFIG) drives for variable-speed wind power generation. The control algorithm of the grid-connected 3L-NPC-VSC applies the concepts of the decoupled vector control method, which provides independent control active and reactive power flow and maintain the dc-link voltage constant. The simulation

W. Srirattanawichaikul; Y. Kumsuwan; S. Premrudeepreechacharn; B. Wu

2010-01-01

141

Polymer vectors via controlled\\/living radical polymerization for gene delivery  

Microsoft Academic Search

The design of efficient gene delivery vectors is a challenging task in gene therapy. Recent progress in living\\/controlled radical polymerizations (LRPs), in particular atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain transfer (RAFT) polymerization providing a means for the design and synthesis of new polymeric gene vectors with well-defined compositions, architectures and functionalities is reviewed here. Polymeric gene vectors

F. J. Xu; W. T. Yang

2011-01-01

142

The Effective Population Size of Malaria Mosquitoes: Large Impact of Vector Control  

PubMed Central

Malaria vectors in sub-Saharan Africa have proven themselves very difficult adversaries in the global struggle against malaria. Decades of anti-vector interventions have yielded mixed results—with successful reductions in transmission in some areas and limited impacts in others. These varying successes can be ascribed to a lack of universally effective vector control tools, as well as the development of insecticide resistance in mosquito populations. Understanding the impact of vector control on mosquito populations is crucial for planning new interventions and evaluating existing ones. However, estimates of population size changes in response to control efforts are often inaccurate because of limitations and biases in collection methods. Attempts to evaluate the impact of vector control on mosquito effective population size (Ne) have produced inconclusive results thus far. Therefore, we obtained data for 13–15 microsatellite markers for more than 1,500 mosquitoes representing multiple time points for seven populations of three important vector species—Anopheles gambiae, An. melas, and An. moucheti—in Equatorial Guinea. These populations were exposed to indoor residual spraying or long-lasting insecticidal nets in recent years. For comparison, we also analyzed data from two populations that have no history of organized vector control. We used Approximate Bayesian Computation to reconstruct their demographic history, allowing us to evaluate the impact of these interventions on the effective population size. In six of the seven study populations, vector control had a dramatic impact on the effective population size, reducing Ne between 55%–87%, the exception being a single An. melas population. In contrast, the two negative control populations did not experience a reduction in effective population size. This study is the first to conclusively link anti-vector intervention programs in Africa to sharply reduced effective population sizes of malaria vectors.

Athrey, Giridhar; Hodges, Theresa K.; Reddy, Michael R.; Overgaard, Hans J.; Matias, Abrahan; Ridl, Frances C.; Kleinschmidt, Immo; Caccone, Adalgisa; Slotman, Michel A.

2012-01-01

143

Vector control intervention towards interruption of transmission of Chagas disease by Rhodnius prolixus, main vector in Guatemala.  

PubMed

In Guatemala, the Ministry of Health (MoH) began a vector control project with Japanese cooperation in 2000 to reduce the risk of Chagas disease infection. Rhodnius prolixus is one of the principal vectors and is targeted for elimination. The control method consisted of extensive residual insecticide spraying campaigns, followed by community-based surveillance with selective respraying. Interventions in nine endemic departments identified 317 villages with R. prolixus of 4,417 villages surveyed. Two cycles of residual insecticide spraying covered over 98% of the houses in the identified villages. Fourteen villages reinfestated were all resprayed. Between 2000-2003 and 2008, the number of infested villages decreased from 317 to two and the house infestation rate reduced from 0.86% to 0.0036%. Seroprevalence rates in 2004-2005, when compared with an earlier study in 1998, showed a significant decline from 5.3% to 1.3% among schoolchildren in endemic areas. The total operational cost was US$ 921,815, where the cost ratio between preparatory, attack and surveillance phases was approximately 2:12:1. In 2008, Guatemala was certified for interruption of Chagas disease transmission by R. prolixus. What facilitated the process was existing knowledge in vector control and notable commitment by the MoH, as well as political, managerial and technical support by external stakeholders. PMID:23147143

Hashimoto, Ken; Alvarez, Hugo; Nakagawa, Jun; Juarez, Jaime; Monroy, Carlota; Cordón-Rosales, Celia; Gil, Enrique

2012-11-01

144

Adaptative Variable Structure Control for an Online Tuning Direct Vector Controlled Induction Motor Drives  

NASA Astrophysics Data System (ADS)

This study demonstrates that high performance speed control can be obtained by using an adaptative sliding mode control method for a direct vector controlled Squirrel Cage Induction Motor (SCIM). In this study a new method of designing a simple and effective adaptative sliding mode rotational speed control law is developed. The design includes an accurate sliding mode flux observation from the measured stator terminals and rotor speed. The performance of the Direct Field-Orientation Control (DFOC) is ensured by online tuning based on a Model Reference Adaptative System (MRAS) rotor time constant estimator. The control strategy is derived in the sense of Lyapunov stability theory so that the stable tracking performance can be guaranteed under the occurrence of system uncertainties and external disturbances. The proposed scheme is a solution for a robust and high performance induction motor servo drives. Simulation results are provided to validate the effectiveness and robustness of the developed methodology.

Lasaad, Sbita; Dalila, Zaltni; Naceurq, Abdelkrim Mohamed

145

Implementation of a direct control algorithm for induction motors based on discrete space vector modulation  

Microsoft Academic Search

The basic concept of direct torque control of induction machines is investigated in order to emphasize the effects produced by a given voltage vector on stator flux and torque variations. The low number of voltage vectors which can be applied to the machine using the basic DTC scheme may cause undesired torque and current ripple. An improvement of the drive

Domenico Casadei; Giovanni Serra; K. Tani

2000-01-01

146

A Simple and Generalized Space Vector PWM Control of Cascaded H-Bridge Multilevel Inverters  

Microsoft Academic Search

This paper presents an automatic switching pattern generation for multilevel cascaded H-bridge inverters with equal dc voltage sources, based on the space-vector pulse width modulation (SVPWM) techniques. The proposed switching strategy generates a voltage vector with very low harmonic distortion and reduced switching frequency. This new control method is an attractive alternative to the classic multilevel pulse width modulation techniques

Kartick Chandra Jana; S. K. Biswas; P. Thakura

2006-01-01

147

An experimental investigation of active control of thrust vectoring nozzle flow fields  

Microsoft Academic Search

Fluidic thrust vector control is examined in a supersonic rectangular jet having a 4:1 aspect ratio. Experiments conducted at a Mach number of 2 reveal that the thrust vector angle of the jet can be continuously varied by up to at least 16 deg by applying a counterflowing stream to one of the primary jet shear layers. A technique using

P. J. Strykowski; A. Krothapalli

1994-01-01

148

A new method of rotor resistance estimation for vector-controlled induction machines  

Microsoft Academic Search

The estimation of rotor time constant, or rotor resistance, in a vector-controlled induction machine is necessary to achieve high-performance torque control. A new method of estimating the rotor resistance online, for use in a vector-controlled induction machine, is presented. It uses short duration pulses added to the constant flux reference current idse* and based on the resultant torque command current

Scott Wade; W. Dunnigan; Barry W. Williams

1997-01-01

149

A new approach to sensorless vector control of SPMSM with adaptive sliding-mode observer  

Microsoft Academic Search

This paper presents a new approach to the sensorless vector control of a surface permanent magnet synchronous motor (SPMSM). It shows that the time-delay, in electrical rotor position estimation, does not influence the vector control when the d- and q-axis current components are accurately estimated. The PI controllers, fed by the actual d-and q-axis current errors, generate the correct voltage

Luigi SALVATORE; Francesco CUPERTINO; Giuseppe L. CASCELLA

2002-01-01

150

Multichannel vector field control module for LLRF control of superconducting cavities  

SciTech Connect

The field control of multiple superconducting RF cavities with a single Klystron, such as the proposed RF scheme for the ILC, requires high density (number of RF channels) signal processing hardware so that vector control may be implemented with minimum group delay. The MFC (Multichannel Field Control) module is a 33-channel, FPGA based down-conversion and signal processing board in a single VXI slot, with 4 channels of high speed DAC outputs. A 32-bit, 400MHz floating point DSP provides additional computational and control capability for calibration and implementation of more complex control algorithms. Multiple high speed serial transceivers on the front panel and the backplane bus allow a flexible architecture for inter-module real time data exchanges. An interface CPLD supports the VXI bus protocol for communication to a Slot0 CPU, with Ethernet connections for remote in system programming of the FPGA and DSP as well as data acquisition.

Varghese, P; Chase, B.; Barnes, B.; Branlard, J.; Joireman, P.W.; Klepec, D.; Mavric, U.; Tupikov, V.; /Fermilab

2007-06-01

151

Development and qualification of a STAR 48 rocket motor with thrust vector control  

NASA Astrophysics Data System (ADS)

A thrust vector control (TVC) nozzle for use on the STAR 48 rocket motor (STAR 48V) has been developed for use on the COMET program aboard the Conestoga launch vehicle. The first stages of qualification testing have been completed. The first STAR 48V has been successfully static-tested. The flexseal TVC nozzle design is based upon the qualified and flight-proven fixed nozzle design used on spin-stabilized spacecraft. The flexseal design and fabrication approach benefit from flight-proven and man-rated Thiokol Corporation flexseal designs. The thrust vector control system provides vectoring capability to 4 deg for use on nonspinning spacecraft. Electromechanical actuators coupled with a closed-loop controller provide thrust vector positioning and spacecraft attitude control.

Hamke, R.; Rade, J.; Weldin, R.

1992-07-01

152

Comparison of cytokine plasma levels in human African trypanosomiasis  

Microsoft Academic Search

Summary background Immunological studies suggest that human African trypanosomiasis (HAT) is associated with inflammatory responses. A better understanding of the complex cytokine interactions regulating HAT infections is essential to elucidate the mechanisms of generalized immunosuppression. method We determined levels of interleukin (IL)-2, IL-4, IL-6, IL-10, tumour necrosis factor (TNF)-a and interferon (IFN)-c protein levels in plasma samples from three groups

David Courtin; Vincent Jamonneau; Jean-Francois Mathieu; Mathurin Koffi; Jacqueline Milet; Claude Sese Yeminanga; Victor Kande Betu Kumeso; Gerard Cuny; Constantin Miaka Mia Bilengue; Andre Garcia

2006-01-01

153

Speed estimation of vector controlled squirrel cage asynchronous motor with artificial neural networks  

Microsoft Academic Search

In this paper, the artificial neural networks as a sensorless speed estimator in indirect vector controlled squirrel cage asynchronous motor control are defined. High dynamic performance power semi conductors obtainable from direct current motors can also be obtained from asynchronous motor through developments in digital signal processors (DSP) and control techniques. With using of field diverting control in asynchronous motors,

Yuksel Oguz; Mehmet Dede

2011-01-01

154

Comparison between direct and vector control strategy for VSC-HVDC system in EMTP-RV  

Microsoft Academic Search

This paper presents a detailed comparison of direct and vector control strategies for a Voltage Source Converter (VSC) operated HVDC transmission system. The system is, simulated with EMTP-RV simulation package, to investigate its operational performance. The simulation results with both control strategies shows a satisfactory performance under steady state behaviour, but, due to cross-coupling between the control parameters direct control

Vijay Sood; Hiteshkumar Patel

2010-01-01

155

Vector-Field-Orientation Feedback Control Method for a Differentially Driven Vehicle  

Microsoft Academic Search

This paper presents a novel vector-field-orientation (VFO) feedback control method and its application to a differentially driven wheeled vehicle. It describes the control concept and the control design methodology originating from simple geometrical interpretations connected with the vehicle model structure. The novelty of the VFO method allows one to treat two considered control tasks - trajectory tracking and point stabilization

M. Michaek; K. Kozowski

2010-01-01

156

A rare case of human trypanosomiasis caused by Trypanosoma evansi.  

PubMed

Human trypanosoma infections like the ones seen in Africa and South America are unknown in India. The only exception in literature is of two documented cases of a self-limiting febrile illness, being attributed to Trypanosoma lewisi like parasites. We are reporting an unusual case of trypanosomiasis from the rural parts of Chandrapur district in Maharashtra. An adult male farmhand who used to practice veterinary medicine also, presented with history of febrile episodes on and off since five months and drowsiness before admission to this Institute. Though routine blood and other investigations were within normal limits, the peripheral smear showed a large number of trypanosomes which morphologically resembled the species Trypanosoma evansi, the aetiological agent of surra - a form of animal trypanosomiasis. A battery of assays covering the spectrum of parasitology, serology, and molecular biology confirmed the infecting parasite to be T. evansi. Failure to demonstrate the central nervous system (CNS) involvement, as evidenced by the absence of parasite in cerebrospinal fluid (CSF) advocated the use of suramin - the drug of choice in early stage African trypanosomiasis without any CNS involvement. Suramin achieved cure in our patient. The case is being reported because of its unique nature as the patient was not immunocompromised and showed infestation with a parasite which normally does not affect human beings. PMID:16505565

Powar, R M; Shegokar, V R; Joshi, P P; Dani, V S; Tankhiwale, N S; Truc, P; Jannin, J; Bhargava, A

2006-01-01

157

Cost-Effectiveness of Chagas Disease Vector Control Strategies in Northwestern Argentina  

Microsoft Academic Search

BackgroundControl and prevention of Chagas disease rely mostly on residual spraying of insecticides. In Argentina, vector control shifted from a vertical to a fully horizontal strategy based on community participation between 1992 and 2004. The effects of such strategy on Triatoma infestans, the main domestic vector, and on disease transmission have not been assessed.Methods and FindingsBased on retrospective (1993–2004) records

Gonzalo M. Vazquez-Prokopec; Cynthia Spillmann; Mario Zaidenberg; Uriel Kitron; Ricardo E. Gürtler

2009-01-01

158

Sensorless vector control of synchronous reluctance motors with disturbance torque observer  

Microsoft Academic Search

The elimination of the position sensor has been one important requirement in vector control systems because the position sensor spoils the reliability and simplicity of drive systems. Therefore, we present a sensorless vector control technique for synchronous reluctance motors. The rotor position is calculated easily from ds-qs-axes flux linkages which are estimated with a first-order lag compensator. Furthermore, utilizing estimated

Tomonobu Senjyu; Takeshi Shingaki; Katsumi Uezato

2001-01-01

159

Implementation of sensorless vector control for super-high-speed PMSM of turbo-compressor  

Microsoft Academic Search

This paper describes the implementation of two vector control schemes for a variable-speed 131-kW permanent-magnet synchronous motor drive in super-high-speed applications. The vector control with a synchronous reference frame current regulator was implemented with challenging requirements such as an extremely low stator inductance (28 ?H), a high DC-link voltage (600 V), and a high excitation frequency (1.2 kHz). Because the

Bon-Ho Bae; Seung-Ki Sul; Jeong-Hyeck Kwon; Ji-Seob Byeon

2003-01-01

160

Bayesian Geostatistical Analysis and Prediction of Rhodesian Human African Trypanosomiasis  

PubMed Central

Background The persistent spread of Rhodesian human African trypanosomiasis (HAT) in Uganda in recent years has increased concerns of a potential overlap with the Gambian form of the disease. Recent research has aimed to increase the evidence base for targeting control measures by focusing on the environmental and climatic factors that control the spatial distribution of the disease. Objectives One recent study used simple logistic regression methods to explore the relationship between prevalence of Rhodesian HAT and several social, environmental and climatic variables in two of the most recently affected districts of Uganda, and suggested the disease had spread into the study area due to the movement of infected, untreated livestock. Here we extend this study to account for spatial autocorrelation, incorporate uncertainty in input data and model parameters and undertake predictive mapping for risk of high HAT prevalence in future. Materials and Methods Using a spatial analysis in which a generalised linear geostatistical model is used in a Bayesian framework to account explicitly for spatial autocorrelation and incorporate uncertainty in input data and model parameters we are able to demonstrate a more rigorous analytical approach, potentially resulting in more accurate parameter and significance estimates and increased predictive accuracy, thereby allowing an assessment of the validity of the livestock movement hypothesis given more robust parameter estimation and appropriate assessment of covariate effects. Results Analysis strongly supports the theory that Rhodesian HAT was imported to the study area via the movement of untreated, infected livestock from endemic areas. The confounding effect of health care accessibility on the spatial distribution of Rhodesian HAT and the linkages between the disease's distribution and minimum land surface temperature have also been confirmed via the application of these methods. Conclusions Predictive mapping indicates an increased risk of high HAT prevalence in the future in areas surrounding livestock markets, demonstrating the importance of livestock trading for continuing disease spread. Adherence to government policy to treat livestock at the point of sale is essential to prevent the spread of sleeping sickness in Uganda.

Wardrop, Nicola A.; Atkinson, Peter M.; Gething, Peter W.; Fevre, Eric M.; Picozzi, Kim; Kakembo, Abbas S. L.; Welburn, Susan C.

2010-01-01

161

Status of pesticide management in the practice of vector control: a global survey in countries at risk of malaria or other major vector-borne diseases  

PubMed Central

Background It is critical that vector control pesticides are used for their acceptable purpose without causing adverse effects on health and the environment. This paper provides a global overview of the current status of pesticides management in the practice of vector control. Methods A questionnaire was distributed to WHO member states and completed either by the director of the vector-borne disease control programme or by the national manager for vector control. In all, 113 countries responded to the questionnaire (80% response rate), representing 94% of the total population of the countries targeted. Results Major gaps were evident in countries in pesticide procurement practices, training on vector control decision making, certification and quality control of pesticide application, monitoring of worker safety, public awareness programmes, and safe disposal of pesticide-related waste. Nevertheless, basic conditions of policy and coordination have been established in many countries through which the management of vector control pesticides could potentially be improved. Most countries responded that they have adopted relevant recommendations by the WHO. Conclusions Given the deficiencies identified in this first global survey on public health pesticide management and the recent rise in pesticide use for malaria control, the effectiveness and safety of pesticide use are being compromised. This highlights the urgent need for countries to strengthen their capacity on pesticide management and evidence-based decision making within the context of an integrated vector management approach.

2011-01-01

162

Evaluation of Spatially Targeted Strategies to Control Non-Domiciliated Triatoma dimidiata Vector of Chagas Disease  

PubMed Central

Background Chagas disease is a major neglected tropical disease with deep socio-economical effects throughout Central and South America. Vector control programs have consistently reduced domestic populations of triatomine vectors, but non-domiciliated vectors still have to be controlled efficiently. Designing control strategies targeting these vectors is challenging, as it requires a quantitative description of the spatio-temporal dynamics of village infestation, which can only be gained from combinations of extensive field studies and spatial population dynamic modelling. Methodology/Principal Findings A spatially explicit population dynamic model was combined with a two-year field study of T. dimidiata infestation dynamics in the village of Teya, Mexico. The parameterized model fitted and predicted accurately both intra-annual variation and the spatial gradient in vector abundance. Five different control strategies were then applied in concentric rings to mimic spatial design targeting the periphery of the village, where vectors were most abundant. Indoor insecticide spraying and insect screens reduced vector abundance by up to 80% (when applied to the whole village), and half of this effect was obtained when control was applied only to the 33% of households closest to the village periphery. Peri-domicile cleaning was able to eliminate up to 60% of the vectors, but at the periphery of the village it has a low effect, as it is ineffective against sylvatic insects. The use of lethal traps and the management of house attractiveness provided similar levels of control. However this required either house attractiveness to be null, or ?5 lethal traps, at least as attractive as houses, to be installed in each household. Conclusion/Significance Insecticide and insect screens used in houses at the periphery of the village can contribute to reduce house infestation in more central untreated zones. However, this beneficial effect remains insufficient to allow for a unique spatially targeted strategy to offer protection to all households. Most efficiently, control should combine the use of insect screens in outer zones to reduce infestation by both sylvatic and peri-domiciliated vectors, and cleaning of peri-domicile in the centre of the village where sylvatic vectors are absent. The design of such spatially mixed strategies of control offers a promising avenue to reduce the economic cost associated with the control of non-domiciliated vectors.

Barbu, Corentin; Dumonteil, Eric; Gourbiere, Sebastien

2011-01-01

163

Application of three controls optimally in a vector-borne disease - a mathematical study  

NASA Astrophysics Data System (ADS)

We have proposed and analyzed a vector-borne disease model with three types of controls for the eradication of the disease. Four different classes for the human population namely susceptible, infected, recovered and vaccinated and two different classes for the vector populations namely susceptible and infected are considered. In the first part of our analysis the disease dynamics are described for fixed controls and some inferences have been drawn regarding the spread of the disease. Next the optimal control problem is formulated and solved considering control parameters as time dependent. Different possible combination of controls are used and their effectiveness are compared by numerical simulation.

Kar, T. K.; Jana, Soovoojeet

2013-10-01

164

Launching the first postgraduate diploma in medical entomology and disease vector control in Pakistan.  

PubMed

The Health Services Academy has launched a 12-month postgraduate diploma course in medical entomology and disease vector control. The objective is to create a core of experts trained to prevent and control vector-borne diseases. The course is a response to the serious health and socioeconomic burden caused by a number of vector-borne diseases in Pakistan. The persistence, emergence and re-emergence of these diseases is mainly attributed to the scarcity of trained vector-control experts. The training course attempts to fill the gap in trained manpower and thus reduce the morbidity and mortality due to these diseases, resulting in incremental gains to public health. This paper aims to outline the steps taken to establish the course and the perceived challenges to be addressed in order to sustain its future implementation. PMID:21495592

Rathor, H R; Mnzava, A; Bile, K M; Hafeez, A; Zaman, S

2010-01-01

165

BIONOMICS AND SYSTEMATICS OF THE ORIENTAL ANOPHELES SUNDAICUS COMPLEX IN RELATION TO MALARIA TRANSMISSION AND VECTOR CONTROL  

Microsoft Academic Search

The taxonomic history, distribution, bionomics, systematics, and vector control strategies for the Anoph- eles sundaicus complex are reviewed in relation to malaria epidemiology. The lack of data on the bionomics, insecticide resistance, and vector capacity, as well as the general lack of surveillance and monitoring of potential vector populations, make the development of targeted control measures problematic. It will be

ISABELLE DUSFOUR; RALPH E. HARBACH; SYLVIE MANGUIN

2004-01-01

166

The risk and dynamics of onchocerciasis recrudescence after cessation of vector control.  

PubMed Central

Using a computer simulation study, we have investigated the risk and dynamics of onchocerciasis recrudescence after stopping vector control, in order to provide guidelines for operational decision-making in the Onchocerciasis Control Programme in West Africa (OCP). For this purpose, we used the microsimulation model ONCHOSIM to predict for periods of 9-15 years of vector control the ensuing risk and dynamics of recrudescence in an onchocerciasis focus. The model was quantified and validated using OCP evaluation and field research data. A range of plausible values was determined for important confounding parameters, i.e., vector biting rate, variation in exposure between individuals, parasite life span, and the relation between skin microfilarial load and vector infection. Different model quantifications were used in order to take account of the possible confounding effect of these parameters on the prediction of recrudescence. In the absence of immigration of infected humans or invasion by infected flies, the model predicts that 14 years of full-scale vector control are required to reduce the risk of recrudescence to less than 1%. The risk depends, in particular, on the vector biting rate, and this has implications for the planning of post-larviciding surveillance. Recrudescence will be a relatively slow process, and its rate will depend on the duration of vector control. Even if vector control were stopped too early, i.e., after 12-13 years in a highly endemic area, it would take more than 20 years before the intensity of infection in the community would reach levels of public health importance.

Plaisier, A. P.; van Oortmarssen, G. J.; Remme, J.; Alley, E. S.; Habbema, J. D.

1991-01-01

167

The research of arrange transition course in vector control of PMSM  

Microsoft Academic Search

In the research of digital vector control system of permanent magnet synchronous machine (PMSM), double loop control system was chosen, in which a PID controller was adopted in the speed and the current loop. Some problems such as overshoot, long response time and the small range of speed regulating appear. To deal with these problems, this paper discussed the methods

Zhang Xin; Wang Yunkuan; Zheng Jun

2008-01-01

168

Improved direct torque and flux vector control of PWM inverter-fed induction motor drives  

Microsoft Academic Search

In this paper, a direct torque and stator flux vector control system is presented. The principle of this method was proposed by Takahashi and Noguchi in 1985. In contrast to the field oriented control, no coordinate transformation and current control loop is required. In practical application, however, problems occur with starting and operation in the zero speed region. This paper

Marian P. Kazmierkowski; Andrzej B. Kasprowicz

1995-01-01

169

FPGA based Space Vector PWM Control IC for Three Phase Induction Motor Drive  

Microsoft Academic Search

In conventional digital motor controllers, the PWM gating signal generation, current control loop for stator current regulation, dead time generation and other computational tasks requires high sampling rate to achieve wide bandwidth performance. To relieve the controller from the time consuming computational task of PWM signal generation, a novel method of Space Vector PWM signal generation is implemented in FPGA

R. K. PongiannanI; N. Yadaiah

2006-01-01

170

An optimal current vector control for synchronous reluctance motors incorporating field weakening  

Microsoft Academic Search

In this paper, a new approach to the synchronous reluctance motor control that ensures the production of maximum torque over the entire field weakening region is presented. In other words, this paper presents an optimal control scheme for wide speed range operation of synchronous reluctance motor drives, where current vector is directly controlled. The proposed scheme possesses some attractive features

Kaveh Malekian; Mohammad Reza Sharif; Jafar Milimonfared

2008-01-01

171

Trajectory tracking control for the planar dynamics of a thrust vectored airship  

Microsoft Academic Search

This paper addresses and solves the trajectory tracking problem for the planar dynamics of a thrust vectored airship. The proposed controller is based on a combination of two nonlinear control design techniques, backstepping and exact tracking error dynamics passive output feedback (ETDPOF). Numerical simulations show the performance of the proposed controller and some concluding remarks complete the paper.

G. Murguia-Rendon; H. Rodriguez-Cortes; M. Velasco-Villa

2009-01-01

172

Robust synthesized control of electromechanical actuator for thrust vector system in spacecraft  

Microsoft Academic Search

A kind of robust control of electromechanical actuator (EMA) system for thrust vector control in a spacecraft was investigated. In the flight of a spacecraft, the EMA system must overcome the influence of load disturbance and working point alteration to improve the robust control performances. Addressing this problem and considering the large inertia and low stiffness load of the EMA

Hao Lu; Yunhua Li; Chenglin Zhu

173

Expansion of operating limits for permanent magnet motor by current vector control considering inverter capacity  

Microsoft Academic Search

The current vector control method of PM (permanent magnet) motors is examined to expand the operating limits associated with inverter capacity. This control method is optimum in the sense of deriving maximum output torque within the voltage and current constraints. The effects of motor parameters are examined by computer simulation. The operating limits are greatly expanded by controlling the d-

S. Morimoto; Y. Takeda; T. Hirasa; K. Taniguchi

1990-01-01

174

Iron core losses: measurement and impact in induction motor vector control  

Microsoft Academic Search

In the present paper, the influence of iron core losses on the vector controlled induction motor performance is-presented. The equivalent iron core loss resistance is experimentally identified from no-load tests with PWM and sinusoidal supplies. The amount of detuning caused by the iron core losses is analysed for indirect rotor flux oriented control (RFOC) and stator flux oriented control (SFOC)

M. Benhaddadi; O. Touhami; S. Moulahoum; G. Olivier

1998-01-01

175

Power smoothing in wind generation systems using a sensorless vector controlled induction Machine driving a flywheel  

Microsoft Academic Search

This paper presents a novel control strategy for power smoothing in generation systems in which power flow variations can occur. These variations are the norm in wind energy generation. The system is based on a sensorless vector controlled induction machine driving a flywheel. The induction machine is controlled to operate in a wide speed range by using flux weakening above

Roberto Cárdenas; Rubén Peña; Greg Asher; Jon Clare

2004-01-01

176

Vector Topics Number 4 - Biology and Control of 'Aedes aegypti'.  

National Technical Information Service (NTIS)

Contents: Public health importance of Aedes aegypti; Biology and habits of Aedes aegypti; Surveillance of Aedes aegypti populations; Control of Aedes aegypti; Evaluation of control measures; Control during disease outbreaks.

1979-01-01

177

Required duration of combined annual ivermectin treatment and vector control in the Onchocerciasis Control Programme in west Africa.  

PubMed Central

In the extension areas of the Onchocerciasis Control Programme in West Africa, aerial larviciding is supplemented with annual ivermectin treatment, mainly to achieve better control of morbidity. The purpose of this study is to determine whether and to what extent the addition of annual ivermectin treatment permits earlier cessation of vector control than originally recommended. The effectiveness of combined ivermectin distribution and vector control was assessed using an epidemiological model. Model predictions suggest that, dependent on the pre-control endemicity of the area and the proportion of persons treated during each ivermectin round, large-scale annual treatment permits a considerable reduction in the duration of vector control. Taking into account uncertainty about the efficacy of ivermectin, our results indicate that, provided treatment coverage is at least 65% and there is no importation of infection from elsewhere, 12 years of combined control will be sufficient to reduce the risk of recrudescence to below 1% in even the most afflicted areas.

Plaisier, A. P.; Alley, E. S.; van Oortmarssen, G. J.; Boatin, B. A.; Habbema, J. D.

1997-01-01

178

Future challenges for parasitology: vector control and one health in the Americas.  

PubMed

"One Health" is a term that encapsulates and underscores the inherent interrelatedness of the health of people, animals, and the environment. Vector-borne infections are central in one health. Many arthropod vectors readily feed on humans and other animals, serving as an ideal conduit to move pathogens between a wide spectrum of potential hosts. As ecological niches flux, opportunities arise for vectors to interact with novel species, allowing infectious agents to broaden both geographic and host ranges. Habitat change has been linked to the emergence of novel human and veterinary disease agents, and can dramatically facilitate expansion opportunities by allowing existing vector populations to flourish and by supporting the establishment of new pathogen maintenance systems. At the same time, control efforts can be hindered by the development of parasiticide and pesticide resistance, foiling efforts to meet these challenges. Using examples drawn from representative diseases important in one health in the Americas, including rickettsial infections, Lyme borreliosis, Chagas disease, and West Nile virus, this paper reviews key aspects of vector-borne disease maintenance cycles that present challenges for one health in the Americas, including emergence of vector-borne disease agents, the impact of habitat change on vector-borne disease transmission, and the complexities faced in developing effective control programs. Novel strategies will be required to effectively combat these infections in the future if we are to succeed in the goal of fostering an environment which supports healthy animals and healthy people. PMID:23623185

Little, Susan E

2013-04-06

179

Vector control strategy for small-scale grid-connected PMSG wind turbine converter  

Microsoft Academic Search

The purpose of this paper is to find an innovative, high efficiency, practical and low cost control system structure with an optimized control strategy for small-scale grid-connected wind turbine with direct-driven permanent magnet synchronous generator (PMSG). This research adopts the sensorless vector control strategy based on phase-locked loop (PLL) for PMSG control, and the grid-side inverter control strategy is based

Chunxue Wen; Guojie Lu; Peng Wang; Zhengxi Li; Xiongwei Liu; Zaiming Fan

2011-01-01

180

Fuzzy logic based on-line efficiency optimization control of an indirect vector-controlled induction motor drive  

Microsoft Academic Search

Improvement of adjustable speed drive system efficiency is important not only from the viewpoints of energy saving and cooling system operation, but also from the broad perspective of environmental pollution. The paper describes a fuzzy logic based on-line efficiency optimization control of a drive that uses an indirect vector controlled induction motor speed control system in the inner loop. At

G. C. D. Sousa; Bimal K. Bose; John G. Cleland

1995-01-01

181

Vector control interventions for visceral leishmaniasis elimination initiative in South Asia, 2005-2010  

PubMed Central

The Visceral Leishmaniasis (VL) Elimination Initiative in the Indian subcontinent was launched in 2005 as a joint effort between the governments in the Region (India, Nepal and Bangladesh) and the World Health Organization (WHO). The objective is to reduce the annual VL incidence below 1/10,000 inhabitants by 2015 based on detection and treatment of VL cases and vector control. We present here a review of studies published in the period 2005-2010 on the efficacy of different tools to control Phlebotomus argentipes. The review indicates that the current indoor residual spraying (IRS) and novel vector control methods mainly insecticide treated nets (ITN) have low effectiveness for several reasons. Efforts to improve quality of IRS operations and further research on alternative and integrated vector control methods need to be promoted to reach the VL elimination target by 2015.

Picado, Albert; Dash, Aditya P.; Bhattacharya, Sujit; Boelaert, Marleen

2012-01-01

182

Control of Ducted Fan Flying Object Using Thrust Vectoring  

NASA Astrophysics Data System (ADS)

Recently, R/C helicopter is used in fields of aerial photography and aerial investigation. But helicopter rotor blades are not covered, and the thrust is generated by high rotational speed. Thus R/C helicopter has a high risk of damage. In this study, we developed a new flying object using ducted fans instead of rotor blades. At first, PD control was employed for pitch and roll attitude control, but it caused steady state error. Moreover, PI-D control was used instead of PD control, and it reduced the steady state error. We succeeded to achieve stable hovering by 3-axes (roll, pitch and yaw axis) attitude control.

Miwa, Masafumi; Shigematsu, Yuki; Yamashita, Takashi

183

Fuzzy logic based rotor resistance estimator of an indirect vector controlled induction motor drive  

Microsoft Academic Search

A simple method for estimating rotor resistance in an indirect vector-controlled induction motor drive is proposed in this paper. The proposed rotor resistance estimator which uses fuzzy logic principle is based on the improvement of control performance when mismatch between estimated rotor resistance and actual one occurs. Analysis, design, and digital simulations are carried out to demonstrate the effectiveness of

Y. Miloud; A. Draou

2002-01-01

184

Performance of vector controlled induction motor drive with reactive power based MRAS rotor resistance estimator  

Microsoft Academic Search

In this paper, a detailed study of the performance of Vector Controlled Induction Motor drive with Model Reference Adaptive System (MRAS) based Rotor Resistance Estimator using Reactive Power is presented. The rotor resistance changes significantly during operation due to temperature rise. This variation has a major influence on the field oriented control performance of an induction motor drive due to

M. Nandhini Gayathri; S. Himavathi; R. Sankaran

2011-01-01

185

A Rotor Parameter Identification Scheme for Vector-Controlled Induction Motor Drives  

Microsoft Academic Search

A rotor parameter identification technique for the purpose of updating the control gains of an induction motor vector controller is described. The approach utilizes the current source nature of a current-regulated PWM inverter by injecting a prescribed negative sequence current perturbation signal. The corresponding negative sequence voltage is sensed and decomposed into its d and q components. By injecting the

Takayoshi Matsuo; Thomas A. Lipo

1985-01-01

186

Multilevel Space Vector PWM Control Schemes for a Flying Capacitor Inverter  

Microsoft Academic Search

The paper presents three different computational schemes for achieving space vector pulse width modulation, in the control of a multilevel flying capacitor inverter. Each scheme uses the same method of achieving cell-capacitor voltage balancing. Results of realistic simulations are used to compare and contrast these approaches. The timing control of the inverter switches and output performance of each method are

S. J. Watkins; L Zhang

187

Modeling and vector control of synchronous reluctance motors including stator iron loss  

Microsoft Academic Search

The influence of the stator iron loss cannot be neglected since the high-speed operation and precision torque control of AC motors are required. This paper presents the modeling and vector control of synchronous reluctance motors including the stator iron loss. The stator iron loss is modeled by additional windings on the d-q axes, and is introduced as an equivalent iron

Katsumi Uezato; Tomonobu Senjyu; Yoshikatsu Tomori

1994-01-01

188

Mosquito vector biology and control in Latin America - a 20TH symposium  

Technology Transfer Automated Retrieval System (TEKTRAN)

The 20th Annual Latin American symposium presented by the American Mosquito Control Association (AMCA) was held as part of the 76th Annual Meeting in Lexington, KY in March 2010. The principal objective, as for the previous 19 symposia, was to promote participation in the AMCA by vector control spec...

189

Mosquito vector biology and control in Latin America - a 22nd Symposium  

Technology Transfer Automated Retrieval System (TEKTRAN)

The 22nd Annual Latin American Symposium presented by the American Mosquito Control Association (AMCA) was held as part of the 78th Annual Meeting in Austin, TX in February 2012. The principal objective, as for the previous 21 symposia, was to promote participation in the AMCA by vector control spec...

190

MOSQUITO VECTOR CONTROL AND BIOLOGY IN LATIN AMERICA - A 19TH SYMPOSIUM  

Technology Transfer Automated Retrieval System (TEKTRAN)

The 19th Annual Latin American symposium presented by the American Mosquito Control Association (AMCA) was held as part of the 75th Annual Meeting in New Orleans, LA, in April 2009. The principal objective, as for the previous 18 symposia, was to promote participation in the AMCA by vector control s...

191

MOSQUITO VECTOR CONTROL AND BIOLOGY IN LATIN AMERICA- An 18TH SYMPOSIUM  

Technology Transfer Automated Retrieval System (TEKTRAN)

The 18th Annual Latin American symposium presented by the American Mosquito Control Association (AMCA) was held as part of the 74th Annual Meeting in Sparks, NV, in March 2008. The principal objective, as for the previous 17 symposia, was to promote participation in the AMCA by vector control speci...

192

Mosquito vector biology and control in Latin America - A 21st symposium  

Technology Transfer Automated Retrieval System (TEKTRAN)

The 21st Annual Latin American Symposium presented by the American Mosquito Control Association (AMCA) was held as part of the 77th Annual Meeting in Anaheim, CA in March 2011. The principal objective, as for the previous 20 symposia, was to promote participation in the AMCA by vector control specia...

193

Posture Control of Electromechanical-Actuator-Based Thrust Vector System for Aircraft Engine  

Microsoft Academic Search

This paper deals with the dynamical modeling and posture control of the electromechanical actuator (EMA)-based thrust vector control (TVC) system for aircraft engines. Addressing the issues of the large inertia and low stiffness existing in the TVC system driven by EMA, this paper established a 2-DOF mathematical model to describe the EMA dynamic characteristics. In order to overcome the influence

Yunhua Li; Hao Lu; Shengli Tian; Zongxia Jiao; Jian-Tao Chen

2012-01-01

194

Loss minimization in vector-controlled interior permanent-magnet synchronous motor drives  

Microsoft Academic Search

An efficiency optimization method for vector-controlled interior permanent-magnet synchronous motor drives is presented. Based on theoretical analysis, a loss minimization condition that determines the optimal d-axis component of the armature current is derived. Selected experimental results are presented to validate the effectiveness of the proposed control method.

Christos Mademlis; Nikos Margaris

2002-01-01

195

Chattering-free sliding mode control based on support vector regression  

Microsoft Academic Search

In order to deal with time delay in the system and saturation in the input, a new chattering free support vector regression sliding mode control (SVR-SMC) law based on 1(LMIs) is proposed. The sign function of reaching law in conventional sliding mode control (SMC) is replaced by output of SVR. An equivalent matrix is constructed for input saturation condition in

Linsheng Li; Jianning Li

2008-01-01

196

Simultaneous thrust vector control and vibration isolation of satellites using steerable smart platforms  

Microsoft Academic Search

This paper presents an innovative concept, control strategies and experimental verification of simultaneous thrust vector control and vibration isolation of satellites. First, the innovative concept is introduced by employing a smart platform as an active structural interface between the main thruster of a satellite and the satellite structure. Second, the inverse kinematics and singularity analysis of the smart platform are

Mehrdad N. Ghasemi-Nejhad; Kougen Ma

2010-01-01

197

High-Performance Vector-Controlled AC Motor Drives: Applications and New Technologies  

Microsoft Academic Search

A high-performance ac motor control has been developed by employing the vector control concept. Its versatility has been proven through the six years of experience in applications to pinch roll drives of continuous casting plants, machine tool spindle drives, and other drive systems in industry. Equivalent torque characteristics are achieved with ac motors compared to dc motors without direct detection

Tsuneo Kume; Takanobu Iwakane

1987-01-01

198

Adaptive-speed identification scheme for a vector-controlled speed sensorless inverter-induction motor drive  

Microsoft Academic Search

The authors describe a model reference adaptive control system for speed control of the vector-controlled inverter induction motor drive without a speed sensor. The rotor speed is estimated with a full-order adaptive observer and is used as the feedback signal for the vector and speed controls. In order to estimate the speed accurately at low speeds, the motor stator resistance

Geng Yang; Tung-Hai Chin

1993-01-01

199

A network population model of the dynamics and control of African malaria vectors.  

PubMed

A more robust assessment of malaria control through mosquito larval habitat destruction will come from a better understanding of the distribution, productivity and connectivity of breeding sites. The present study examines the significance of vector dispersal ability, larval habitat stability and productivity on the persistence and extinction of a mosquito population inhabiting a dynamic network of breeding sites. We use this novel method of vector modelling to show that when dispersal is limited or vector distribution is patchy, the spread and growth of a mosquito population at the onset of a rainy season is delayed and extinction through larval habitat destruction is more readily achieved. We also determine the impact of two alternative dry-season survival strategies on mosquito dynamics. Simulations suggest that if adult vectors remain dormant throughout the dry season, the stage structure of the population will be synchronized at the onset of the wet season and its growth will be delayed. In contrast, a population that continues to breed throughout the dry season grows more rapidly and is more difficult to control. Our findings have important implications on the development of integrative malaria vector management strategies and on the understanding of dry-season survival mechanisms of African malaria vectors. PMID:20813387

Yakob, Laith; Yan, Guiyun

2010-10-01

200

A set of ontologies to drive tools for the control of vector-borne diseases  

PubMed Central

We are developing a set of ontologies dealing with vector-borne diseases as well as the arthropod vectors that transmit them. After building ontologies for mosquito and tick anatomy we continued this project with an ontology of insecticide resistance followed by a series of ontologies that describe malaria as well as physiological processes of mosquitoes that are relevant to, and involved in, disease transmission. These will later be expanded to encompass other vector-borne diseases as well as non-mosquito vectors. The aim of the whole undertaking, which is worked out in the frame of the international IDO (Infectious Disease Ontology) project, is to provide the community with a set of ontological tools that can be used both in the development of specific databases and, most importantly, in the construction of decision support systems (DSS) to control these diseases.

Topalis, Pantelis; Dialynas, Emmanuel; Mitraka, Elvira; Deliyanni, Elena; Siden-Kiamos, Inga; Louis, Christos

2010-01-01

201

Position Sensorless Vector Control for Permanent Magnet Synchronous Motors Based on Maximum Torque Control Frame  

NASA Astrophysics Data System (ADS)

High efficiency drive can be achieved by the maximum torque-per-ampere (MTPA) control which used reluctance torque effectively. However, the calculations for estimating rotor position and for controlling the d-axis current are required. The motor parameters of inductance etc. that are easily affected by magnetic saturation are included in those calculations. This paper proposes a new MTPA control method, which is robust against changes of motor parameters caused by magnetic saturation. In addition, complex calculation for d-axis current or reference to the table is not necessary. In this method, we define a novel coordinate frame, which has one axis aligned with the current vector of the MTPA control, and estimate the frame directly. Because the parameter Lqm for estimating the frame is less affected by the magnetic saturation than the conventional Lq, the effect of magnetic saturation on the position estimation can be greatly suppressed. First, an extended electromotive force model based on the proposed frame and a parameter Lqm for an estimation of the frame are derived. Next, the effectiveness of this proposed method is confirmed by simulations and experiments.

Hida, Hajime; Tomigashi, Yoshio; Kishimoto, Keiji

202

An experimental investigation of active control of thrust vectoring nozzle flow fields  

NASA Astrophysics Data System (ADS)

Fluidic thrust vector control is examined in a supersonic rectangular jet having a 4:1 aspect ratio. Experiments conducted at a Mach number of 2 reveal that the thrust vector angle of the jet can be continuously varied by up to at least 16 deg by applying a counterflowing stream to one of the primary jet shear layers. A technique using counterflow eliminates the bistable response known to plague fluidic elements and is shown to be effective in both hot and cold supersonic jets. Results are presented for jet stagnation temperatures between 300 K and 670 K. Measurements indicate that the thrust vector control is both efficient as well as a linear function of the static pressure developed in the counterflowing stream. The typical power required to vector the jet at 16 degrees was estimated to be less than 1 percent of the power developed in the primary jet. Thrust vector control employing counterflow has several advantages over current technologies, the most important of which is the elimination of movable control surfaces which add considerable weight to the aircraft.

Strykowski, P. J.; Krothapalli, A.

1994-01-01

203

Effects of uncompensated vector control on synchronous reluctance motor performance  

Microsoft Academic Search

The performance of a synchronous reluctance motor digital controller based on a saturated dq model without compensation for slotting and iron loss influences is investigated. The model predictions for the machine torque characteristics at various speeds including standstill, and the effects of using simplified control strategies are verified by experimental results. Issues related to the low cost software implementation of

M. G. Jovanovic; Robert E. Betz

1999-01-01

204

Eliminating onchocerciasis after 14 years of vector control: a proved strategy.  

PubMed

From 1976 through 1989, weekly aerial spraying operations against blackflies were carried out along the rivers of a wide savanna area of West Africa (approximately 700,000 km(2)) where onchocerciasis was hyperendemic. The level of endemicity began to decrease significantly after 4 years of vector control and became very low in 1989. This situation has been maintained without any vector control activity or chemotherapy, and no incidence of any new cases has been detected. An ophthalmological study carried out in 2000 has confirmed these good results, showing only cicatricial ocular lesions in the examined population. These results led to the conclusion that 14 years of vector control may achieve long-term elimination of onchocerciasis, even in the absence of chemotherapy, provided that the treated areas are not subjected to any contamination by exogenous parasites carried in infected humans or flies. PMID:11471108

Hougard, J M; Alley, E S; Yaméogo, L; Dadzie, K Y; Boatin, B A

2001-07-16

205

Vector model utilization for nested-loop rotor Brushless Doubly-Fed Machine analysis, control and simulation  

Microsoft Academic Search

This paper presents different applications of a vector model developed by the authors in Brushless Doubly-Fed Machine (BDFM) studies including analysis, control and simulations. The BDFM considered consists of a nested-loop type rotor. The vector model, which considers all the loops in each rotor nest, is derived using BDFM coupled-circuit model equations and by applying appropriate vector transformations. Three vector

Farhad Barati; Hashem Oraee

2010-01-01

206

Rotating vector methods for smooth torque control of a switched reluctance motor drive  

SciTech Connect

This paper has two primary contributions to switched reluctance motor (SRM) control: a systematic approach to smooth torque production and a high-performance technique for sensorless motion control. The systematic approach to smooth torque production is based on development of novel rotating spatial vectors methods that can be used to predict the torque produced in an arbitrary SRM. This analysis directly leads to explicit, insightful methods to provide smooth torque control of SRM's. The high-performance technique for sensorless motion control is based on a rotating vector method for high bandwidth, high resolution, position, and velocity estimation suitable for both precise torque and motion control. The sensorless control and smooth torque control methods are both verified experimentally.

Nagel, N.J.; Lorenz, R.D.

2000-04-01

207

CONTROL OF PATHOGENS AND VECTORS IN SEWAGE SLUDGE  

EPA Science Inventory

This document describes the federal requirements concerning pathogens in sewage sludge and septage destined for land application or surface disposal. t also provides guidance for meeting those requirements. he chapters of this document discuss why pathogen control is necessary, t...

208

A Small-molecule-controlled System for Efficient Pseudotyping of Prototype Foamy Virus Vectors  

PubMed Central

Foamy virus (FV) vector systems have recently demonstrated their power as efficient gene transfer tools for different target tissues. Unfortunately, FVs cannot be naturally pseudotyped by heterologous viral glycoproteins due to an unusual particle morphogenesis involving a FV Env-dependent particle release process. Therefore, current FV vector systems are constrained to the broad host cell range provided by the cognate viral glycoprotein. We evaluated different approaches for pseudotyping of FV vectors, in which the specific FV Gag–Env interaction, essential for particle egress, is substituted by a small-molecule controlled heterodimerization (HD) system. In one system developed, one HD-domain (HDD) is fused to a membrane-targeting domain (MTD), such as the human immunodeficiency virus (HIV) Gag matrix (MA) subunit, with a second fused to the FV capsid protein. Coexpression of both components with different heterologous viral glycoproteins allowed an efficient, dimerizer-dependent pseudotyping of FV capsids. With this system FV vesicular stomatitis virus glycoprotein (VSV-G) pseudotype titers greater than 1 × 106 IU/ml were obtained, at levels comparable to authentic FV vector particles. As a proof-of-principle we demonstrate that Pac2 cells, naturally resistant to FV vectors, become permissive to FV VSV-G pseudotypes. Similar to other retroviral vectors, this FV pseudotyping system now enables adaptation of cell-specific targeting approaches for FVs.

Ho, Yu-Ping; Schnabel, Viktor; Swiersy, Anka; Stirnnagel, Kristin; Lindemann, Dirk

2012-01-01

209

Tsetse-fly control and eradication*  

PubMed Central

In many instances the cheapest and quickest way of controlling trypanosomiasis is to reduce the number of vectors and the opportunities for contact between man and vector. For permanent results, moreover, eradication of the vectors is necessary, since eradication of trypanosomiasis by chemotherapeutic means has so far not proved feasible. For a variety of reasons, game destruction as a method of fly control is gradually being replaced by other methods. Of these, the complete removal of bush cover will always effectively eradicate tsetse flies, but in order to save time, labour and money, partial clearing (selective or discriminative) is more usually resorted to. Provided this is preceded by extensive and accurate surveys of fly infestation, it is generally successful. Blanket applications of insecticides from aircraft or from ground aerosol machines can give good and rapid results; however, as knowledge of the habits and behaviour of Glossina species grows, the discriminative application of insecticides can be made more precise, economical and effective. This method of using the residual insecticides seems to be the most promising for the future.

Hocking, K. S.; Lamerton, J. F.; Lewis, E. A.

1963-01-01

210

Development of a low-harmonic vector hysteresis current controller  

Microsoft Academic Search

Abstract. The increasing interest in the use of renewable energy sources for the generation of electrical energy makes itnecessary,to ensure ,that these type of installations do ,not jeopardize the global operation of the ,electrical system ,to which they are connected. Up until now, this safety has been achieved by imposing ,very strict limits to the percentage of “non-controllable” renewable ,energy

J. F. Sanz; J. Sallán; M. Alonso; M. Sanz; J. L. Villa

211

Short report: Human trypanosomiasis caused by Trypanosoma evansi in a village in India: preliminary serologic survey of the local population.  

PubMed

After discovery of the first recorded case of human infection with Trypanosoma evansi, serologic screening of 1,806 persons from the village of origin of the patient in India was performed using the card agglutination test for trypanosomiasis and T. evansi. A total of 410 (22.7%) people were positive by whole blood, but only 81 were confirmed positive by serum. However, no trypanosomes were detected in the blood of 60 people who were positive at a high serum dilution. The results probably indicate frequent exposure of the human population to T. evansi in the study area, which suggests frequent vector transmission of parasites to humans. Although T. evansi is not infective for humans, a follow-up of seropositive persons is required to observe the evolution of human infection with this parasite. PMID:17123979

Shegokar, Vijay R; Powar, Rajaram M; Joshi, Prashant P; Bhargava, Aradhana; Dani, Vibhawari S; Katti, Ravindra; Zare, Vasant R; Khanande, Vithhalrao D; Jannin, Jean; Truc, Philippe

2006-11-01

212

Performance Analysis of a Fuzzy Logic Based Rotor Resistance Estimator of an Indirect Vector Controlled Induction Motor Drive  

Microsoft Academic Search

This paper presents a simple method for estimating rotor resistance in an indirect vector-controlled induction motor drive. This is important in vector control, if high-performance torque control is needed. For this purpose, a rotor resistance estimator using fuzzy logic technique is used and analysis, design, and digital simulations are carried out to demonstrate the eectiveness of the proposed estimator.

Y. MILOUD; A. DRAOU

2005-01-01

213

Induction-motor sensorless vector control with online parameter estimation and overcurrent protection  

Microsoft Academic Search

Sensorless drive control has been widely studied in recent years due to the numerous advantages regarding potential failures of position sensors, especially in applications such as automotive or aerospace. Among vector-control drives, indirect rotor-flux-oriented control (IRFOC) type is one of the most popular and tested options. However, it is still a challenging field since several aspects can be improved, such

Mario J. Durán; José L. Durán; Francisco Pérez; José Fernández

2006-01-01

214

On-line adaptive artificial neural network based vector control of permanent magnet synchronous motors  

Microsoft Academic Search

This paper presents a novel approach of speed control for a permanent magnet synchronous motor (PMSM) using on-line self tuning artificial neural network (ANN). Based on motor dynamics and nonlinear load characteristics, an ANN speed controller is developed and integrated with the vector control scheme of the PMSM drive. The combined use of off-line and on-line weights and biases adjustments

M. A. Rahman; M. A. Hoque

1998-01-01

215

Community-based dengue vector control: experiences in behavior change in Metropolitan Manila, Philippines.  

PubMed

Dengue is the most important mosquito-borne disease in the Philippines, especially in Metropolitan Manila where communities are socially and economically diverse, and city governments struggle to provide basic services such as continuously available, piped water supply to residents. We examined responses to introducing water container management to control dengue vectors in two diverse communities in Masagana City: Village A (gated community) and Village B (informal settlers community). The roll out of the intervention was carried out by the study team, dengue control personnel and local health workers (BHWs). A behavioural change framework was used to describe the community responses to the introduction of a new vector control intervention - household water container management. Although, the desired outcome was not achieved during the study's timeline, observation on processes of behaviour change underscored the importance of understanding the social nature of the urban communities, often overlooked structures when dengue control program and researchers introduce new dengue control interventions. PMID:23318237

Espino, Fe; Marco, Jesusa; Salazar, Nelia P; Salazar, Ferdinand; Mendoza, Ysadora; Velazco, Aldwin

2012-12-01

216

Mosquito vector control and biology in Latin America--an 18th symposium.  

PubMed

The 18th Annual Latin American symposium presented by the American Mosquito Control Association (AMCA) was held as part of the 74th Annual Meeting in Sparks, NV, in March 2008. The principal objective, as for the previous 17 symposia, was to promote participation in the AMCA by vector control specialists, public health workers, and academicians from Latin America. This publication includes summaries of 35 presentations that were given orally in Spanish or presented as posters by participants from 5 countries in Latin America and Puerto Rico. Topics addressed in the symposium included surveillance, chemical and biological control, insecticide resistance, and repellency of Aedes aegypti; distribution, behavior, transmission of West Nile virus, and control of Culex; bionomics, ecology, and chemical and biological control of Anopheles vectors of malaria; insecticide resistance; and studies of Triatoma and Rhodnius. PMID:19181067

Clark, Gary G; Rubio-Palis, Yasmin

2008-12-01

217

Mosquito vector biology and control in Latin America--a 22nd symposium.  

PubMed

The 22nd Annual Latin American Symposium presented by the American Mosquito Control Association (AMCA) was held as part of the 78th Annual Meeting in Austin, TX, in February 2012. The principal objective, as for the previous 21 symposia, was to promote participation in the AMCA by vector control specialists, public health workers, and academicians from Latin America. This publication includes summaries of 21 presentations that were given orally in Spanish or presented as posters by participants from Mexico, Colombia, Venezuela, and the USA. Topics addressed in the symposium included surveillance, chemical control, insecticide resistance, and genetics associated with Aedes aegypti; food sources and control of Culex; taxonomy, surveillance, and control of Anopheles vectors of malaria; and studies of dengue virus and Leishmania. PMID:22894120

Clark, Gary G; Rubio-Palis, Yasmin

2012-06-01

218

Mosquito vector biology and control in Latin America--a 20th symposium.  

PubMed

The 20th Annual Latin American Symposium presented by the American Mosquito Control Association (AMCA) was held as part of the 76th Annual Meeting in Lexington, KY, in March 2010. The principal objective, as for the previous 19 symposia, was to promote participation in the AMCA by vector control specialists, public health workers, and academicians from Latin America. This publication includes summaries of 40 presentations that were given orally in Spanish or presented as posters by participants from 5 countries in Latin America, the United Kingdom, and the USA. Topics addressed in the symposium included: surveillance, chemical and biological control, and insecticide resistance associated with Aedes aegypti; distribution, behavior, and control of Culex; bionomics, ecology, and chemical and biological control of Anopheles vectors of malaria; insecticide resistance; and studies of dengue, West Nile virus, and Triatoma. PMID:21033058

Clark, Gary G; Rubio-Palis, Yasmin

2010-09-01

219

A cluster-randomized trial of insecticide-treated curtains for dengue vector control in Thailand.  

PubMed

The efficacy of insecticide-treated window curtains (ITCs) for dengue vector control was evaluated in Thailand in a cluster-randomized controlled trial. A total of 2,037 houses in 26 clusters was randomized to receive the intervention or act as control (no treatment). Entomological surveys measured Aedes infestations (Breteau index, house index, container index, and pupae per person index) and oviposition indices (mean numbers of eggs laid in oviposition traps) immediately before and after intervention, and at 3-month intervals over 12 months. There were no consistent statistically significant differences in entomological indices between intervention and control clusters, although oviposition indices were lower (P < 0.01) in ITC clusters during the wet season. It is possible that the open housing structures in the study reduced the likelihood of mosquitoes making contact with ITCs. ITCs deployed in a region where this house design is common may be unsuitable for dengue vector control. PMID:23166195

Lenhart, Audrey; Trongtokit, Yuwadee; Alexander, Neal; Apiwathnasorn, Chamnarn; Satimai, Wichai; Vanlerberghe, Veerle; Van der Stuyft, Patrick; McCall, Philip J

2012-11-19

220

Spatial targeted vector control in the highlands of Burundi and its impact on malaria transmission  

PubMed Central

Background Prevention of malaria epidemics is a priority for African countries. The 2000 malaria epidemic in Burundi prompted the government to implement measures for preventing future outbreaks. Case management with artemisinin-based combination therapy and malaria surveillance were nationally improved. A vector control programme was initiated in one of the most affected highland provinces. The focal distribution of malaria vectors in the highlands was the starting point for designing a targeted vector control strategy. The objective of this study was to present the results of this strategy on malaria transmission in an African highland region. Methods In Karuzi, in 2002–2005, vector control activities combining indoor residual spraying and long-lasting insecticidal nets were implemented. The interventions were done before the expected malaria transmission period and targeted the valleys between hills, with the expectation that this would also protect the populations living at higher altitudes. The impact on the Anopheles population and on malaria transmission was determined by nine cross-sectional surveys carried out at regular intervals throughout the study period. Results Anopheles gambiae s.l. and Anopheles funestus represented 95% of the collected anopheline species. In the valleys, where the vector control activities were implemented, Anopheles density was reduced by 82% (95% CI: 69–90). Similarly, transmission was decreased by 90% (95% CI: 63%–97%, p = 0.001). In the sprayed valleys, Anopheles density was further reduced by 79.5% (95% CI: 51.7–91.3, p < 0.001) in the houses with nets as compared to houses without them. No significant impact on vector density and malaria transmission was observed in the hill tops. However, the intervention focused on the high risk areas near the valley floor, where 93% of the vectors are found and 90% of the transmission occurs. Conclusion Spatial targeted vector control effectively reduced Anopheles density and transmission in this highland district. Bed nets have an additional effect on Anopheles density though this did not translate in an additional impact on transmission. Though no impact was observed in the hilltops, the programme successfully covered the areas most at risk. Such a targeted strategy could prevent the emergence and spread of an epidemic from these high risk foci.

Protopopoff, Natacha; Van Bortel, Wim; Marcotty, Tanguy; Van Herp, Michel; Maes, Peter; Baza, Dismas; D'Alessandro, Umberto; Coosemans, Marc

2007-01-01

221

Rotor resistance identification using artificial neural networks for an indirect vector controlled induction motor drive  

Microsoft Academic Search

This paper presents a new method of estimation for the rotor resistance of the induction motor in the indirect vector controlled drive. The back propagation neural network technique is used for the real time adaptive estimation. The error between the desired state variable of an induction motor and the actual state variable of a neural model is back propagated to

B. Karanayil; M. F. Rahman; C. Grantham

2001-01-01

222

An effective method for rotor resistance identification for high-performance induction motor vector control  

Microsoft Academic Search

An effective method for rotor resistance identification is presented for the purpose of improving the performance of vector control of induction motor drives. The method is mathematically derived from proper selection of coordinate axes and utilization of the steady-state model of the induction motor. The major advantages of the method lie in its simplicity and accuracy. A series of computer

C. C. Chan; HUAQIAN WANG

1990-01-01

223

Speed sensorless vector control of induction motor using extended Kalman filter  

Microsoft Academic Search

A vector control of an induction motor by an estimated speed using an extended Kalman filter is proposed. With this method, the states are composed of stator current and rotor flux. The rotor speed is regarded as a parameter, and the composite states consist of the original states and the rotor speed. The extended Kalman filter is employed to identify

Young-Real Kim; Seung-Ki Sul; Min-Ho Park

1994-01-01

224

Robust speed identification for speed sensorless vector control of induction motors  

Microsoft Academic Search

An approach to estimating induction motor speed from measured terminal voltages and currents for speed-sensorless vector control is described. The proposed technique is very simple and robust to variations of motor parameters. This approach is not dependent upon the knowledge of the value of the stator resistance, nor is it affected by stator-resistance thermal variations. Pure integration of sensed variables,

Fang-Zheng Peng; Tadashi Fukao

1993-01-01

225

Blazed vector gratings fabricated using photosensitive polymer liquid crystals and control of polarization diffraction  

NASA Astrophysics Data System (ADS)

The blazed vector grating possessing antisymmetric distributions of the birefringence were fabricated by exposing the line-focused linearly polarized ultraviolet light on the photosensitive polymer liquid crystals. The polarization states of the diffraction beams can be highly and widely controlled by designing the blazed structures, and the diffraction properties were well-explained by Jones calculus.

Ono, Hiroshi; Kuzuwata, Mitsuru; Sasaki, Tomoyuki; Noda, Kohei; Kawatsuki, Nobuhiro

2013-06-01

226

Adaptive Speed Sensorless Vector Control of Induction Motor using Singularly Perturbed Sliding Mode Observer  

Microsoft Academic Search

This paper presents a new approach for sensorless vector control of induction motor using singularly perturbed sliding mode observer. This approach is based on the singular perturbation theory which decomposes the original system of the observer error dynamics into separate slow and fast subsystems and permits a simple design and sequential determination of the observer gains. In this way, the

A. Mezouar; M. K. Fellah; S. Hadjeri; Y. Sahali

2006-01-01

227

A robust fuzzy speed estimation for vector control of an induction motor  

Microsoft Academic Search

This work addresses the analysis and the design of an adaptive fuzzy sliding-mode observer applied to vector control of an induction motor. The conception steps for the conventional sliding-mode speed observer (SMO) are laid down clearly. In this work, the drawbacks of SMO in terms of high observer gains and chattering phenomenon due of switching surface are overcome by merging

K. Kouzi; M.-S. Nait-Said; M. Hilairet; E. Berthlot

2009-01-01

228

High power factor correction circuits with space vector and hysteresis control methods  

Microsoft Academic Search

This paper presents a new topology of the three-phase ac to dc converter. Only three ac switches are required to perform the power factor correction. The series connection of the two output capacitors is adapted to employ the high dc output voltage. A space vector modulation strategy is used to control two of the three ac switches at any time,

Bor-Ren Lin; Deng-Ping Wu

1997-01-01

229

MOSQUITO VECTOR CONTROL AND BIOLOGY IN LATIN AMERICA - A 16TH SYMPOSIUM  

Technology Transfer Automated Retrieval System (TEKTRAN)

The 16th Annual Latin American Symposium presented by the American Mosquito Control Association (AMCA) was held as part of the 72nd Annual Meeting in Detroit, Michigan in February 2006. The principal objective, as for the previous 15 symposia, was to promote participation in the AMCA by vector cont...

230

Mosquito Vector Control and Biology in Latin America - A 17th Symposium  

Technology Transfer Automated Retrieval System (TEKTRAN)

The 17th Annual Latin America American symposium presented by the American Mosquito Control Association (AMCA) was held as part of the 73rd Annual Meeting in Orlando, FL, in April 2007. The principal objective, as for the previous 16 symposia, was to promote participation in the AMCA by vector cont...

231

High Thrust to Weight Bipropellant Reentry Vehicle Thrust Vector Control Thru Micro-Miniaturization.  

National Technical Information Service (NTIS)

With the advent of nanosat and picosat-size satellites, the design of miniature, efficient, high thrust-to-weight (T/W) ratio thrust vector control (TVC) thrusters with liquid bipropellants has been evolving. The extremely high T/W ratios achievable with ...

W. Figueiredo

2003-01-01

232

CURRENT STATUS OF THE MOSQUITO BACULOVIRUS CUNINPV FOR CONTROL OF CULEX VECTORS OF ENCEPHALITIS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Baculoviruses have been intensively investigated due to their potential as biological control agents for insects and because of their importance as gene expression vectors. Mosquito baculoviruses have been difficult if not impossible to transmit and therefore basic biological studies have been hind...

233

Oviposition Site Selection by the Dengue Vector Aedes aegypti and Its Implications for Dengue Control  

Microsoft Academic Search

BackgroundBecause no dengue vaccine or antiviral therapy is commercially available, controlling the primary mosquito vector, Aedes aegypti, is currently the only means to prevent dengue outbreaks. Traditional models of Ae. aegypti assume that population dynamics are regulated by density-dependent larval competition for food and little affected by oviposition behavior. Due to direct impacts on offspring survival and development, however, mosquito

Jacklyn Wong; Steven T. Stoddard; Helvio Astete; Amy C. Morrison; Thomas W. Scott

2011-01-01

234

An integral space-vector PWM technique for DSP-controlled voltage-source inverters  

Microsoft Academic Search

A novel pulsewidth modulation (PWM) technique for voltage-source inverters, based on the idea of space vectors of switching integrals is presented. In contrast to most existing PWM methods, no explicit timing is required, smooth transition from the PWM mode to the square-wave mode is ensured, and minimum allowable widths of pulses and notches are guaranteed. The control algorithm is conceptually

Andrzej M. Trzynadlowski; Michael M. Bech; Frede Blaabjerg; John K. Pedersen

1999-01-01

235

Diagnosing human African trypanosomiasis in Angola using a card agglutination test: observational study of active and passive case finding strategies  

PubMed Central

Objective To assess the operational feasibility of detecting human African trypanosomiasis by active and passive case finding using the card agglutination test with serial dilution of serum to guide treatment. Setting Trypanosomiasis control programme in the Negage focus, northern Angola, during a period of civil war. Design Observational study. Participants 359 patients presenting themselves to health centres with symptoms (passive case finding) and 14 446 people actively screened in villages. Main outcome measures Whole blood and serological tests at different dilutions using the card agglutination test, and detection of parasites by microscopy. Results Active case finding identified 251 people with a positive card agglutination test result, 10 of whom had confirmed parasites. In those presenting for investigation 34 of 51 with a positive card agglutination test result at the dilution of 1:8 or more used to guide treatment had parasites in blood, lymph node fluid, or cerebrospinal fluid, compared with 10 of 76 in those detected by active case finding: positive predictive values of 67% for passive case detection and 13% for active case detection. Only at a cut-off dilution more than 1:32 was the positive predictive value in active case detection reasonable (46%) and at this dilution 40% of microscopically proved cases were missed. Conclusions The card agglutination test is useful for initial screening in active detection of cases with human African trypanosomiasis but, given the toxicity of the drugs, serology using the card agglutination test should be not used alone to guide treatment after active case finding. A second confirmatory test is needed.

Inojosa, Walter O; Augusto, Inacio; Bisoffi, Zeno; Josenado, Teofile; Abel, Paulo M; Stich, August; Whitty, Christopher J M

2006-01-01

236

Investigations on the control of bilharziasis vectors in Israel*  

PubMed Central

In spite of the arrival in Israel over the past decade of large numbers of immigrants infected with bilharziasis and although during that period there have been two sporadic outbreaks of the disease, there seems little immediate danger of bilharziasis spreading in the country. However, hydrographical, agricultural and economic conditions are subject to rapid changes in Israel and the present favourable situation may not be lasting. In anticipation, therefore, of possible outbreaks, laboratory experiments have been conducted to evaluate the efficacy in the control of Bulinus ova and adult snails and schistosome cercariae of a number of known molluscides and other substances. Although similar studies have been made in several other countries, it was felt advisable to repeat them under local hydrological conditions, particularly in view of the high carbonate content of the local waters. While most of the substances tested exert some molluscicidal action, only copper sulfate, sodium pentachlorophenate and common salt were found to be of practical value.

Saliternik, Z.; Witenberg, G.

1959-01-01

237

Research on the control of bluetongue in livestock by vector suppression.  

PubMed

From 1979-83, research has been conducted along the South Platte River drainage system northeast of Denver, CO, to develop and evaluate techniques of wide-area vector suppression for the control of bluetongue (BT) disease in ruminant livestock. Water management and chemical treatment at larval development sites have resulted in a decrease in the activity of Culicoides variipennis (Coquillett) in the 100 km2 treatment area, and there is some correlation between levels of vector activity (as reflected by light trap catches) and the levels of BT in livestock as measured by serologic and virologic evaluations. PMID:2989910

Holbrook, F R

1985-01-01

238

Comparative study of fuzzy logic speed controller in vector controlled PMSM drive: Minimum number of fuzzy rule-base  

Microsoft Academic Search

This paper presents a comparative study on fuzzy rule-base of fuzzy logic speed control with vector-controlled permanent magnet synchronous motor (PMSM) drive. Fuzzy rule-base design is viewed as control strategy. All fuzzy rules contribute to some degree in obtaining the desired performance. However, some rules fired weakly do not contribute significantly to the final result and can be eliminated. dasiaStandard

S. N. M. Isa; Z. Ibrahim; F. Patkar

2009-01-01

239

Mosquito vector control and biology in Latin America--a 15th symposium. Abstracts.  

PubMed

The 15th Annual Latin American symposium presented by the American Mosquito Control Association (AMCA) was held as part of the 71st Annual Meeting in Vancouver, British Columbia, Canada, in April 2005. The principal objective, as for the previous 14 symposia, was to promote participation in the AMCA by vector control specialists, public health workers, and academicians from Latin America. This publication includes summaries of 40 presentations that were given orally in Spanish or presented as posters by participants from 8 countries in Latin America and the USA. Topics addressed in the symposium included results from chemical and biological control programs and studies; studies of insecticide resistance; and population genetics, molecular, ecological, and behavioral studies of vectors of dengue (Aedes aegypti and Ae. albopictus) and other arboviruses, malaria (Anopheles albimanus, An. aquasalis, An. neomaculipalpus, An. pseudopunctipennis), leishmaniasis (Lutzomyia), and Chagas Disease (Triatoma), as well as a vaccine for control of Boophilus ticks on cattle. PMID:16570381

Clark, Gary G; Quiroz Martínez, Humberto

2005-12-01

240

A direct torque control scheme for permanent magnet synchronous motors based on space vector modulation  

NASA Astrophysics Data System (ADS)

In order to solve the problem of direct torque control (DTC) for permanent magnet synchronous motor (PMSM) related to the flux and the torque ripple and the uncertainty of switching frequency, A novel direct torque control system based on space vector modulation(SVM-DTC) for permanent magnet synchronous motor was proposed. In this method flux and torque are controlled through stator voltage components in stator flux linkage coordinate axes and space vector modulation is used to control inverters. Therefore, the errors of torque and flux linkage could be compensated accurately. The whole system has only one easily adjustable PI adjuster and needs no high for hardware and easy for realize. The simulation results verify the feasibility of this method, reduction of the flux and the torque ripple, and the good performance of DTC.

Su, Xiao-hui; Xu, Shu-Ping

2013-03-01

241

Mosquito vector control and biology in Latin America--a sixth symposium.  

PubMed

The sixth Spanish language symposium presented by the American Mosquito Control Association (AMCA) was held as part of the 62nd Annual Meeting in Norfolk, VA, in March 1996. The principal objective, as for the previous 5 symposia, was to promote the participation in the AMCA meeting by vector control specialists, public health workers, and academicians from Latin America. This publication includes summaries of 25 presentations that were given in Spanish by participants from 6 countries in Latin America and the USA. The symposium included the following topics: ecological and genetic studies of anopheline vectors of malaria, laboratory and field evaluations of chemical control methods for several mosquito species, ecological studies and community control of Aedes aegypti, and reports of dengue/dengue hemorrhagic fever and Venezuelan equine encephalitis epidemics that occurred in Latin America in 1995. PMID:8887226

Clark, G G

1996-09-01

242

Drivers, dynamics, and control of emerging vector-borne zoonotic diseases.  

PubMed

Emerging vector-borne diseases are an important issue in global health. Many vector-borne pathogens have appeared in new regions in the past two decades, while many endemic diseases have increased in incidence. Although introductions and emergence of endemic pathogens are often considered to be distinct processes, many endemic pathogens are actually spreading at a local scale coincident with habitat change. We draw attention to key differences between dynamics and disease burden that result from increased pathogen transmission after habitat change and after introduction into new regions. Local emergence is commonly driven by changes in human factors as much as by enhanced enzootic cycles, whereas pathogen invasion results from anthropogenic trade and travel where and when conditions (eg, hosts, vectors, and climate) are suitable for a pathogen. Once a pathogen is established, ecological factors related to vector characteristics can shape the evolutionary selective pressure and result in increased use of people as transmission hosts. We describe challenges inherent in the control of vector-borne zoonotic diseases and some emerging non-traditional strategies that could be effective in the long term. PMID:23200503

Kilpatrick, A Marm; Randolph, Sarah E

2012-12-01

243

Global status of DDT and its alternatives for use in vector control to prevent disease.  

PubMed

In this article I reviewed the status of dichlorodiphenyltrichloroethane (DDT), used for disease vector control, and its benefits and risks in relation to the available alternatives. Contemporary data on DDT use were obtained from questionnaires and reports as well as a Scopus search to retrieve published articles. Nearly 14 countries use DDT for disease control, and several others are reintroducing DDT. Concerns about the continued use of DDT are fueled by recent reports of high levels of human exposure associated with indoor spraying amid accumulating evidence on chronic health effects. There are signs that more malaria vectors are becoming resistant to the toxic action of DDT. Effective chemical methods are available as immediate alternatives to DDT, but the development of resistance is undermining the efficacy of insecticidal tools. Nonchemical methods are potentially important, but their effectiveness at program level needs urgent study. To reduce reliance on DDT, support is needed for integrated and multipartner strategies of vector control. Integrated vector management provides a framework for developing and implementing effective technologies and strategies as sustainable alternatives to reliance on DDT. PMID:21340333

van den Berg, Henk

2011-02-01

244

Adaptive speed identification for vector control of induction motors without rotational transducers  

SciTech Connect

This paper describes a model-reference adaptive system (MRAS) for the estimation of induction motor speed from measured terminal voltages and currents. The estimated speed is used as feedback in a vector control system, thus achieving moderate bandwidth speed control without the use of shaft-mounted transducers. This technique is less complex and more stable than previous MRAS tacholess drives. It has been implemented on a 30-hp laboratory drive, where its effectiveness has been verified.

Schauder, C. (Science and Technology Center, Westinghouse Electric Corp., Pittsburgh, PA (United States))

1992-10-01

245

Vector control scheme of synchronous reluctance motor considering iron core loss  

Microsoft Academic Search

This paper proposes a vector control method for the synchronous reluctance motor (SynRM) which selects appropriate stator d,q-axis current component combination (flux current, torque current) so that the influence of iron core loss on the developed torque can be minimized in torque control. A coupled finite element analysis and Preisach's modeling for SynRM is presented to verify the propriety of

Jung Chul Kim; Jung Ho Lee; In Soung Jung; Dong Seok Hyun

1998-01-01

246

Stator-flux-oriented vector control of synchronous reluctance Machines with maximized efficiency  

Microsoft Academic Search

This paper presents a position-sensorless vector torque controller designed to achieve maximum efficiency over a range of power and rotational speed for a synchronous reluctance machine. A model of the synchronous reluctance machine is presented which incorporates both winding and core losses. It is then shown that a stator-flux-oriented control scheme can achieve synchronous operation of the machine without a

Heath F. Hofmann; Seth R. Sanders; A. EL-Antably

2004-01-01

247

DSP based control of high power static VAr compensator using novel vector product phase locked loop  

Microsoft Academic Search

This paper presents a new dual loop control using novel vector product phase locked loop (VP-PLL) for a high power static VAr compensator (SVC) with three-level GTO voltage source inverter (VSl). Through circuit DQ-transformation method, a simple DQ-axis equivalent circuit is obtained. From this, DC analysis is carried out to obtain maximum controllable phase angle ?max per unit current between

Gu H. Jung; Guk C. Cho; Soon W. Hong; Gyu H. Cho

1996-01-01

248

Direct torque controlled space vector modulated induction motor fed by a Z-source inverter for electric vehicles  

Microsoft Academic Search

This paper proposes a new closed loop speed control of an induction motor fed by a high performance Z-source inverter (ZSI), the speed control is based on direct torque control space vector modulation (DTC-SVM) control strategy. The modified space vector modulation (MSVM) is used to insert the shoot-through state within the switching signals for the ZSI. A dual loop controller

Omar Ellabban; Joeri Van Mierlo; Philippe Lataire

2011-01-01

249

Identification of Stage Biomarkers for Human African Trypanosomiasis  

PubMed Central

Human African trypanosomiasis (HAT), caused by infection with sub-species of Trypanosoma brucei (T. b.), manifests as a hemolymphatic stage followed by an encephalitic stage. The distinction of the two stages needs improvement as drugs used for the late stage are highly toxic. Transcripts encoding 16 secreted proteins differentially expressed in the brains of mice at late stage T. b. brucei infection when the early stage drug suramin is no longer effective and different to immunoglobulins, chemokines, and cytokines, were selected by microarray analysis. Lipocalin 2 and secretory leukocyte peptidase inhibitor (SLPI) mRNA showed the highest differential expression in mice. These transcripts were also upregulated in brains from infected rats. Lipocalin 2 was increased in cerebrospinal fluid (CSF) from rats during late stage T. b. brucei infection. Protein levels of lipocalin 2, SLPI, and the chemokine CXCL10 were found increased in CSF from Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense late stage HAT compared to early stage.

Amin, Daniel Ndem; Ngoyi, Dieudonne Mumba; Nhkwachi, Gondwe-Mphepo; Palomba, Maria; Rottenberg, Martin; Buscher, Philippe; Kristensson, Krister; Masocha, Willias

2010-01-01

250

Transmission of chagas disease (American trypanosomiasis) by food.  

PubMed

In April 2009, the centenary of the discovery of the American trypanosomiasis, or Chagas disease, was celebrated. A hundred years after the discovery, little has been invested in diagnostics and treatment because the disease affects mainly poor people in developing countries. However, some changes in the epidemiology of the disease are of great importance today. Chagas disease transmitted through food is a public health concern in all areas where there is a reservoir of Trypanosoma cruzi in wild animals (e.g., mammals and marsupials) and/or where infected triatomine bugs are in contact with human food source items (especially fruits and vegetables). Recently, several outbreaks of illness related to the ingestion of food contaminated with T. cruzi have been recorded in Brazil, Colombia, and Venezuela. PMID:20610174

Pereira, Karen Signori; Schmidt, Flávio Luis; Barbosa, Rodrigo L; Guaraldo, Ana M A; Franco, Regina M B; Dias, Viviane L; Passos, Luiz A C

2010-06-24

251

Mosquito vector control and biology in Latin America--a fourteenth symposium. Abstracts.  

PubMed

The 14th annual Latin American symposium presented by the American Mosquito Control Association (AMCA) was held as part of the 70th Annual Meeting in Savannah, GA, in February 2004. The principal objective, as for the previous 13 symposia, was to promote participation in the AMCA by vector control specialists, public health workers, and academicians from Latin America. This publication includes summaries of 37 presentations that were given orally in Spanish or presented as posters by participants from 7 countries in Latin America. Topics addressed in the symposium included results from chemical and biological control programs and studies; studies of insecticide resistance; and population genetics, molecular, ecological, and behavioral studies of vectors of dengue (Aedes aegypti and Aedes albopictus) and other arboviruses, malaria (Anopheles albimanus and Anopheles pseudopunctipennis), leishmaniasis (Lutzomyia), and Chagas disease (Triatoma). PMID:15669378

Clark, Gary G; Quiroz Martínez, Humberto

2004-12-01

252

Computational dynamic programming for stochastic optimal control on a vector multiprocessor  

SciTech Connect

Numerical methods have been developed to solve optimal feedback control problems for nonlinear, continuous time dynamical systems, perturbed by Poisson as well as Gaussian random white noise. Predictor-corrector methods have been modified for the functional partial differential equation of stochastic dynamic programming to treat nonlinearities attributable to quadratic costs and nonsmoothness attributable to control switching as well as Poisson-induced delays. Uniform corrector convergence conditions are given for the multistate case. This numerical formulation is highly suitable for vectorization and parallelization techniques. These techniques have resulted in speedups of 120 times for the Argonne National Laboratory's Alliant FX/8 vector multiprocessor over a VAX 11/780, when applied to a multistate, multicontrol resource model. Speedups are greater the finer the mesh becomes, because of the dominance of concurrent-outer, vector-inner loops. Column-oriented code can run more than twice as fast as row-oriented code for highly refined meshes, but row-oriented code is more efficient and perhaps practical for coarser meshes. An analytical model of the primary loop structure yields a concurrent-outer, vector-inner loop dominant limit. Addition memory overhead is encountered in performance measurements for large mesh sizes. Advance computing techniques and hardware help alleviate Bellman's ''curse of dimensionality'' in dynamic programming computations. 48 refs., 8 figs.

Hanson, F.B.

1988-06-01

253

Rational spatio-temporal strategies for controlling a Chagas disease vector in urban environments  

PubMed Central

The rational design of interventions is critical to controlling communicable diseases, especially in urban environments. In the case of the Chagas disease vector Triatoma infestans, successful control is stymied by the return of the insect after the effectiveness of the insecticide wanes. Here, we adapt a genetic algorithm, originally developed for the travelling salesman problem, to improve the spatio-temporal design of insecticide campaigns against T. infestans, in a complex urban environment. We find a strategy that reduces the expected instances of vector return 34-fold compared with the current strategy of sequential insecticide application to spatially contiguous communities. The relative success of alternative control strategies depends upon the duration of the effectiveness of the insecticide, and it shows chaotic fluctuations in response to unforeseen delays in a control campaign. We use simplified models to analyse the outcomes of qualitatively different spatio-temporal strategies. Our results provide a detailed procedure to improve control efforts for an urban Chagas disease vector, as well as general guidelines for improving the design of interventions against other disease agents in complex environments.

Levy, Michael Z.; Malaga Chavez, Fernando S.; Cornejo del Carpio, Juan G.; Vilhena, Daril A.; McKenzie, F. Ellis; Plotkin, Joshua B.

2010-01-01

254

Integrated vector management for malaria control in Uganda: knowledge, perceptions and policy development  

PubMed Central

Background Integrated vector management (IVM) is increasingly being recommended as an option for sustainable malaria control. However, many malaria-endemic countries lack a policy framework to guide and promote the approach. The objective of the study was to assess knowledge and perceptions in relation to current malaria vector control policy and IVM in Uganda, and to make recommendations for consideration during future development of a specific IVM policy. Methods The study used a structured questionnaire to interview 34 individuals working at technical or policy-making levels in health, environment, agriculture and fisheries sectors. Specific questions on IVM focused on the following key elements of the approach: integration of chemical and non-chemical interventions of vector control; evidence-based decision making; inter-sectoral collaboration; capacity building; legislation; advocacy and community mobilization. Results All participants were familiar with the term IVM and knew various conventional malaria vector control (MVC) methods. Only 75% thought that Uganda had a MVC policy. Eighty percent (80%) felt there was inter-sectoral collaboration towards IVM, but that it was poor due to financial constraints, difficulties in involving all possible sectors and political differences. The health, environment and agricultural sectors were cited as key areas requiring cooperation in order for IVM to succeed. Sixty-seven percent (67%) of participants responded that communities were actively being involved in MVC, while 48% felt that the use of research results for evidence-based decision making was inadequate or poor. A majority of the participants felt that malaria research in Uganda was rarely used to facilitate policy changes. Suggestions by participants for formulation of specific and effective IVM policy included: revising the MVC policy and IVM-related policies in other sectors into a single, unified IVM policy and, using legislation to enforce IVM in development projects. Conclusion Integrated management of malaria vectors in Uganda remains an underdeveloped component of malaria control policy. Cooperation between the health and other sectors needs strengthening and funding for MVC increased in order to develop and effectively implement an appropriate IVM policy. Continuous engagement of communities by government as well as monitoring and evaluation of vector control programmes will be crucial for sustaining IVM in the country.

2012-01-01

255

Application of H ? control in rudder\\/flap vector robust control of a ship’s course  

Microsoft Academic Search

Given the uncertainty of parameters and the random nature of disturbances that effect a ships course, a robust course controller\\u000a should be designed on the basis of rudder\\/flap vector control. This paper analyzes system uncertainty, and the choice of weighting\\u000a functions is also discussed. When sea waves operate on a ship, the energy-concentrating frequency varies with the angle of\\u000a encounter.

Sheng Liu; Liang Fang

2007-01-01

256

Malaria vector control practices in an irrigated rice agro-ecosystem in central Kenya and implications for malaria control  

Microsoft Academic Search

Background  Malaria transmission in most agricultural ecosystems is complex and hence the need for developing a holistic malaria control\\u000a strategy with adequate consideration of socio-economic factors driving transmission at community level. A cross-sectional\\u000a household survey was conducted in an irrigated ecosystem with the aim of investigating vector control practices applied and\\u000a factors affecting their application both at household and community level.

Peter N Ng'ang'a; Josephat Shililu; Gayathri Jayasinghe; Violet Kimani; Charity Kabutha; Lucy Kabuage; Ephantus Kabiru; John Githure; Clifford Mutero

2008-01-01

257

Human African Trypanosomiasis in South Sudan: How Can We Prevent a New Epidemic?  

PubMed Central

Human African trypanosomiasis (HAT) has been a major public health problem in South Sudan for the last century. Recurrent outbreaks with a repetitive pattern of responding-scaling down activities have been observed. Control measures for outbreak response were reduced when the prevalence decreased and/or socio-political crisis erupted, leading to a new increase in the number of cases. This paper aims to raise international awareness of the threat of another outbreak of sleeping sickness in South Sudan. It is a review of the available data, interventions over time, and current reports on the status of HAT in South Sudan. Since 2006, control interventions and treatments providing services for sleeping sickness have been reduced. Access to HAT diagnosis and treatment has been considerably diminished. The current status of control activities for HAT in South Sudan could lead to a new outbreak of the disease unless 1) the remaining competent personnel are used to train younger staff to resume surveillance and treatment in the centers where HAT activities have stopped, and 2) control of HAT continues to be given priority even when the number of cases has been substantially reduced. Failure to implement an effective and sustainable system for HAT control and surveillance will increase the risk of a new epidemic. That would cause considerable suffering for the affected population and would be an impediment to the socioeconomic development of South Sudan.

Ruiz-Postigo, Jose A.; Franco, Jose R.; Lado, Mounir; Simarro, Pere P.

2012-01-01

258

Multi-cavity complex controller with vector simulator for TESLA technology linear accelerator  

NASA Astrophysics Data System (ADS)

A digital control, as the main part of the Low Level RF system, for superconducting cavities of a linear accelerator is presented. The FPGA based controller, supported by MATLAB system, was developed to investigate a novel firmware implementation. The complex control algorithm based on the non-linear system identification is the proposal verified by the preliminary experimental results. The general idea is implemented as the Multi-Cavity Complex Controller (MCC) and is still under development. The FPGA based controller executes procedure according to the prearranged control tables: Feed-Forward, Set-Point and Corrector unit, to fulfill the required cavity performance: driving in the resonance during filling and field stabilization for the flattop range. Adaptive control algorithm is applied for the feed-forward and feedback modes. The vector Simulator table has been introduced for an efficient verification of the FPGA controller structure. Experimental results of the internal simulation, are presented for a cavity representative condition.

Czarski, Tomasz; Pozniak, Krzysztof T.; Romaniuk, Ryszard S.; Szewinski, Jaroslaw

2008-01-01

259

Spatial predictions of Rhodesian Human African Trypanosomiasis (sleeping sickness) prevalence in Kaberamaido and Dokolo, two newly affected districts of Uganda.  

PubMed

The continued northwards spread of Rhodesian sleeping sickness or Human African Trypanosomiasis (HAT) within Uganda is raising concerns of overlap with the Gambian form of the disease. Disease convergence would result in compromised diagnosis and treatment for HAT. Spatial determinants for HAT are poorly understood across small areas. This study examines the relationships between Rhodesian HAT and several environmental, climatic and social factors in two newly affected districts, Kaberamaido and Dokolo. A one-step logistic regression analysis of HAT prevalence and a two-step logistic regression method permitted separate analysis of both HAT occurrence and HAT prevalence. Both the occurrence and prevalence of HAT were negatively correlated with distance to the closest livestock market in all models. The significance of distance to the closest livestock market strongly indicates that HAT may have been introduced to this previously unaffected area via the movement of infected, untreated livestock from endemic areas. This illustrates the importance of the animal reservoir in disease transmission, and highlights the need for trypanosomiasis control in livestock and the stringent implementation of regulations requiring the treatment of cattle prior to sale at livestock markets to prevent any further spread of Rhodesian HAT within Uganda. PMID:20016846

Batchelor, Nicola A; Atkinson, Peter M; Gething, Peter W; Picozzi, Kim; Fèvre, Eric M; Kakembo, Abbas S L; Welburn, Susan C

2009-12-15

260

Comparing the Effectiveness of Malaria Vector-Control Interventions Through a Mathematical Model  

PubMed Central

Although some malaria-control programs are beginning to combine insecticide-treated nets (ITNs) and indoor residual spraying (IRS), little is known about the effectiveness of such combinations. We use a mathematical model to compare the effectiveness of ITNs and IRS with dichlorodiphenyltrichloroethane (DDT) or bendiocarb, applied singly and in combination, in an epidemiological setting based in Namawala, Tanzania, with Anopheles gambiae as the primary vector. Our model indicates that although both IRS (with DDT) and ITNs provide personal protection, humans with only ITNs are better protected than those with only IRS, and suggests that high coverage of IRS with bendiocarb may interrupt transmission, as can simultaneous high coverage of ITNs and IRS with DDT. When adding a second vector-control intervention, it is more effective to cover the unprotected population first. Although our model includes some assumptions and approximations that remain to be addressed, these findings should be useful for prioritizing and designing future field research.

Chitnis, Nakul; Schapira, Allan; Smith, Thomas; Steketee, Richard

2010-01-01

261

A 40Pulse AC--DC Converter Fed Vector-Controlled Induction Motor Drive  

Microsoft Academic Search

In this paper, a novel autotransformer for a 40-pulse ac-dc converter configuration is designed, modeled, simulated, and implemented to feed vector-controlled induction motor drive (VCIMD). The proposed converter consists of two paralleled ten-pulse ac-dc converters along with pulse doubling circuit at dc bus. Each ten-pulse ac-dc converter involves five-phase diode bridge rectifiers. It improves power quality at ac mains, and

Bhim Singh; Sanjay Gairola

2008-01-01

262

All digital space vector PWM induction motor drive based on flux control  

Microsoft Academic Search

One space vector PWM (SVPWM) method based on closed-loop stator flux control is presented. To realize the method, an all digital voltage source inverter motor system is proposed, in which 2 processors are utilized, one is Hitachi's H8\\/532 single chip processor, the other is TI's TMS320E15 DSP. The system's transient and steady state performance are investigated by means of digital

Li Yong; Huang Lipei; Li Fahai

1993-01-01

263

The potential of a new larviciding method for the control of malaria vectors  

PubMed Central

Malaria pathogens are transmitted to humans by the bite of female Anopheles mosquitoes. The juvenile stages of these mosquitoes develop in a variety of water bodies and are key targets for vector control campaigns involving the application of larvicides. The effective operational implementation of these campaigns is difficult, time consuming, and expensive. New evidence however, suggests that adult mosquitoes can be co-opted into disseminating larvicides in a far more targeted and efficient manner than can be achieved using conventional methods.

2010-01-01

264

Vector control of a synchronous reluctance motor including saturation and iron loss  

Microsoft Academic Search

The application of vector control to a conventional synchronous reluctance motor (VCSynRM) is presented with emphasis on the effects of saturation and iron losses. It is shown experimentally that these parasitic effects can significantly influence the performance of a VCSynRM. A synchronous reference frame steady state model of SynRM including saturation and iron losses is developed. The behavior of a

Longya Xu; Xingyi Xu; Thomas A. Lipo; Donald W. Novotny

1991-01-01

265

Vector control of a synchronous reluctance motor including saturation and iron loss  

Microsoft Academic Search

The application of vector control to a conventional synchronous reluctance motor (VCSynRM) is presented with emphasis on the effects of saturation and iron losses. It is shown experimentally that these parasitic effects can significantly influence the performance of a VCSynRM. A simplified d-q model that includes saturation and iron losses is presented, and experimental results concerning optimal torque\\/ampere and optimal

Longya Xu; Xingyi Xu; T.A. Lipo; D. W. Novotny

1990-01-01

266

Current Prediction in Vector-Controlled PWM Inverters Using Single DC-Link Current Sensor  

Microsoft Academic Search

This paper presents a technique for predicting phase currents in vector-controlled pulsewidth-modulated (PWM) inverters using single dc-link current sensor. There is a limitation for current measurements in the inverters. The measurements are executed in the effective voltages, not in the zero voltage. The current measured in the dc-link and then reconstructed to the phase value is used as a feedback

Jung-Ik Ha

2010-01-01

267

Development and qualification of a STAR 48 rocket motor with thrust vector control  

Microsoft Academic Search

A thrust vector control (TVC) nozzle for use on the STAR 48 rocket motor (STAR 48V) has been developed for use on the COMET program aboard the Conestoga launch vehicle. The first stages of qualification testing have been completed. The first STAR 48V has been successfully static-tested. The flexseal TVC nozzle design is based upon the qualified and flight-proven fixed

R. Hamke; J. Rade; R. Weldin

1992-01-01

268

Use of plant products and copepods for control of the dengue vector, Aedes aegypti  

Microsoft Academic Search

The efficacy of plant extracts (neem tree, Azadirachta indica A. Juss.; Meliaceae) and copepods [Mesocyclops aspericornis (Daday)] for the control of the dengue vector Aedes aegypti L. was tested in the laboratory. Neem Seed Kernel Extract (NSKE) at 25, 50, 100, 200 and 400 ppm caused significant mortality\\u000a of Ae. aegypti larvae. Lethal concentrations (LC50 and LC90) were worked out. The

K. Murugan; Jiang-Shiou Hwang; K. Kovendan; K. Prasanna Kumar; C. Vasugi; A. Naresh Kumar

2011-01-01

269

Temephos Resistance in Aedes aegypti in Colombia Compromises Dengue Vector Control  

PubMed Central

Background Control and prevention of dengue relies heavily on the application of insecticides to control dengue vector mosquitoes. In Colombia, application of the larvicide temephos to the aquatic breeding sites of Aedes aegypti is a key part of the dengue control strategy. Resistance to temephos was recently detected in the dengue-endemic city of Cucuta, leading to questions about its efficacy as a control tool. Here, we characterize the underlying mechanisms and estimate the operational impact of this resistance. Methodology/Principal Findings Larval bioassays of Ae. aegypti larvae from Cucuta determined the temephos LC50 to be 0.066 ppm (95% CI 0.06–0.074), approximately 15× higher than the value obtained from a susceptible laboratory colony. The efficacy of the field dose of temephos at killing this resistant Cucuta population was greatly reduced, with mortality rates <80% two weeks after application and <50% after 4 weeks. Neither biochemical assays nor partial sequencing of the ace-1 gene implicated target site resistance as the primary resistance mechanism. Synergism assays and microarray analysis suggested that metabolic mechanisms were most likely responsible for the temephos resistance. Interestingly, although the greatest synergism was observed with the carboxylesterase inhibitor, DEF, the primary candidate genes from the microarray analysis, and confirmed by quantitative PCR, were cytochrome P450 oxidases, notably CYP6N12, CYP6F3 and CYP6M11. Conclusions/Significance In Colombia, resistance to temephos in Ae. aegypti compromises the duration of its effect as a vector control tool. Several candidate genes potentially responsible for metabolic resistance to temephos were identified. Given the limited number of insecticides that are approved for vector control, future chemical-based control strategies should take into account the mechanisms underlying the resistance to discern which insecticides would likely lead to the greatest control efficacy while minimizing further selection of resistant phenotypes.

Grisales, Nelson; Poupardin, Rodolphe; Gomez, Santiago; Fonseca-Gonzalez, Idalyd; Ranson, Hilary; Lenhart, Audrey

2013-01-01

270

Mapping Neglected Swimming Pools from Satellite Data for Urban Vector Control  

NASA Astrophysics Data System (ADS)

Neglected swimming pools provide suitable breeding habit for mosquitoes, can contain thousands of mosquito larvae, and present both a significant nuisance and public health risk due to their inherent proximity to urban and suburban populations. The rapid increase and sustained rate of foreclosures in California associated with the recent recession presents a challenge for vector control districts seeking to identify, treat, and monitor neglected pools. Commercial high resolution satellite imagery offers some promise for mapping potential neglected pools, and for mapping pools for which routine maintenance has been reestablished. We present progress on unsupervised classification techniques for mapping both neglected pools and clean pools using high resolution commercial satellite data and discuss the potential uses and limitations of this data source in support of vector control efforts. An unsupervised classification scheme that utilizes image segmentation, band thresholds, and a change detection approach was implemented for sample regions in Coachella Valley, CA and the greater Los Angeles area. Comparison with field data collected by vector control personal was used to assess the accuracy of the estimates. The results suggest that the current system may provide some utility for early detection, or cost effective and time efficient annual monitoring, but additional work is required to address spectral and spatial limitations of current commercial satellite sensors for this purpose.

Barker, C. M.; Melton, F. S.; Reisen, W. K.

2010-12-01

271

A Model Framework to Estimate Impact and Cost of Genetics-Based Sterile Insect Methods for Dengue Vector Control  

Microsoft Academic Search

Vector-borne diseases impose enormous health and economic burdens and additional methods to control vector populations are clearly needed. The Sterile Insect Technique (SIT) has been successful against agricultural pests, but is not in large-scale use for suppressing or eliminating mosquito populations. Genetic RIDL technology (Release of Insects carrying a Dominant Lethal) is a proposed modification that involves releasing insects that

Nina Alphey; Luke Alphey; Michael B. Bonsall; Pedro Lagerblad Oliveira

2011-01-01

272

Pyrethroid Resistance in Anopheles gambiae, in Bomi County, Liberia, Compromises Malaria Vector Control  

PubMed Central

Background Long Lasting Insecticidal Nets (LLIN) and Indoor Residual Spraying (IRS) have both proven to be effective malaria vector control strategies in Africa and the new technology of insecticide treated durable wall lining (DL) is being evaluated. Sustaining these interventions at high coverage levels is logistically challenging and, furthermore, the increase in insecticide resistance in African malaria vectors may reduce the efficacy of these chemical based interventions. Monitoring of vector populations and evaluation of the efficacy of insecticide based control approaches should be integral components of malaria control programmes. This study reports on entomological survey conducted in 2011 in Bomi County, Liberia. Methods Anopheles gambiae larvae were collected from four sites in Bomi, Liberia, and reared in a field insectary. Two to five days old female adult An gambiae s.l. were tested using WHO tube (n?=?2027) and cone (n?=?580) bioassays in houses treated with DL or IRS. A sample of mosquitoes (n?=?169) were identified to species/molecular form and screened for the presence of knock down resistance (kdr) alleles associated with pyrethroid resistance. Results Anopheles gambiae s.l tested were resistant to deltamethrin but fully susceptible to bendiocarb and fenithrothion. The corrected mortality of local mosquitoes exposed to houses treated with deltamethrin either via IRS or DL was 12% and 59% respectively, suggesting that resistance may affect the efficacy of these interventions. The presence of pyrethroid resistance was associated with a high frequency of the 1014F kdr allele (90.5%) although this mutation alone cannot explain the resistance levels observed. Conclusion High prevalence of resistance to deltamethrin in Bomi County may reduce the efficacy of malaria strategies relying on this class of insecticide. The findings highlight the urgent need to expand and sustain monitoring of insecticide resistance in Liberian malaria vectors, evaluate the effectiveness of existing interventions and develop appropriate resistance management strategies.

Temu, Emmanuel A.; Maxwell, Caroline; Munyekenye, Godwil; Howard, Annabel F. V.; Munga, Stephen; Avicor, Silas W.; Poupardin, Rodolphe; Jones, Joel J.; Allan, Richard; Kleinschmidt, Immo; Ranson, Hilary

2012-01-01

273

Biochemical evidence of efficacy of potash alum for the control of dengue vector Aedes aegypti (Linnaeus).  

PubMed

Aedes aegypti is the primary vector of dengue, yellow fever and chikungunya in India and other South East Asian countries, and novel insecticides for vector control are urgently needed. In the present investigation, efficacy of potash alum, a traditionally known double salt in Indian and Chinese medicine system, was tested against the larvae of dengue vector, A. aegypti. LC(50,) LC(90) and LC(99) values were recorded for various instar larvae where I instar larvae were found to be the most susceptible and IV instar larvae as the least susceptible one. The LC(50) values of crude and standard potash alum of various instar larvae ranged between 15.29 and 48.53 ppm and 20.50-65.10 ppm, respectively. Biochemical changes were also evidenced in IV instar A. aegypti larvae following a sublethal exposure for 24 h in the levels of various nutrient reserves and primary metabolites such as sugar, glycogen, lipids and proteins suggesting possible mode of action responsible for larval mortality. Sugar and glycogen concentrations were measured as 24.6 and 10.67 ?g per five larvae in controls which were significantly (p<0.05) reduced by 32.11-93.98% and 39.26-94.47%, respectively, in larvae treated with crude alum. In controls, protein and lipid content were recorded as 210.74 and 94.71 ?g per five larvae which dropped up to 26.53% and 25.5%, respectively, in larvae following treatment with crude alum. Moreover, drastic changes were also recorded for DNA content with 25.39-44.17% decrease in crude alum-treated larvae. It is evident from these results that potash alum, a fairly cheaper and readily available ecofriendly compound could be recommended as a potential chemical larvicide against dengue vector at mosquito breeding sites in the vicinity of human dwellings. PMID:21188602

Preet, Shabad; Sneha, A

2010-12-29

274

Modest additive effects of integrated vector control measures on malaria prevalence and transmission in western Kenya  

PubMed Central

Background The effect of integrating vector larval intervention on malaria transmission is unknown when insecticide-treated bed-net (ITN) coverage is very high, and the optimal indicator for intervention evaluation needs to be determined when transmission is low. Methods A post hoc assignment of intervention-control cluster design was used to assess the added effect of both indoor residual spraying (IRS) and Bacillus-based larvicides (Bti) in addition to ITN in the western Kenyan highlands in 2010 and 2011. Cross-sectional, mass parasite screenings, adult vector populations, and cohort of active case surveillance (ACS) were conducted before and after the intervention in three study sites with two- to three-paired intervention-control clusters at each site each year. The effect of larviciding, IRS, ITNs and other determinants of malaria risk was assessed by means of mixed estimating methods. Results Average ITN coverage increased from 41% in 2010 to 92% in 2011 in the study sites. IRS intervention had significant added impact on reducing vector density in 2010 but the impact was modest in 2011. The effect of IRS on reducing parasite prevalence was significant in 2011 but was seasonal specific in 2010. ITN was significantly associated with parasite densities in 2010 but IRS application was significantly correlated with reduced gametocyte density in 2011. IRS application reduced about half of the clinical malaria cases in 2010 and about one-third in 2011 compare to non-intervention areas. Conclusion Compared with a similar study conducted in 2005, the efficacy of the current integrated vector control with ITN, IRS, and Bti reduced three- to five-fold despite high ITN coverage, reflecting a modest added impact on malaria transmission. Additional strategies need to be developed to further reduce malaria transmission.

2013-01-01

275

Global Status of DDT and Its Alternatives for Use in Vector Control to Prevent Disease  

PubMed Central

Objective I review the status of dichlorodiphenyltrichloroethane (DDT), used for disease vector control, along with current evidence on its benefits and risks in relation to the available alternatives. Data sources and extraction Contemporary data on DDT use were largely obtained from questionnaires and reports. I also conducted a Scopus search to retrieve published articles. Data synthesis DDT has been recommended as part of the arsenal of insecticides available for indoor residual spraying until suitable alternatives are available. Approximately 14 countries use DDT for disease control, and several countries are preparing to reintroduce DDT. The effectiveness of DDT depends on local settings and merits close consideration in relation to the alternatives. Concerns about the continued use of DDT are fueled by recent reports of high levels of human exposure associated with indoor spraying amid accumulating evidence on chronic health effects. There are signs that more malaria vectors are becoming resistant to the toxic action of DDT, and that resistance is spreading to new countries. A comprehensive cost assessment of DDT versus its alternatives that takes side effects into account is missing. Effective chemical methods are available as immediate alternatives to DDT, but the choice of insecticide class is limited, and in certain areas the development of resistance is undermining the efficacy of insecticidal tools. New insecticides are not expected in the short term. Nonchemical methods are potentially important, but their effectiveness at program level needs urgent study. Conclusions To reduce reliance on DDT, support is needed for integrated and multipartner strategies of vector control and for the continued development of new technologies. Integrated vector management provides a framework for developing and implementing effective technologies and strategies as sustainable alternatives to reliance on DDT.

van den Berg, Henk

2009-01-01

276

A distributable, display-device-independent vector graphics system for command and control  

NASA Astrophysics Data System (ADS)

This report documents a distributable, device-independent vector graphics system developed by ISI for the Defense Advanced Research Projects Agency. It describes the system architecture, communications elements, and a phased implementation strategy. The system supports graphics-based command and control applications in distributed computational environments such as the ARPANET. The system has been in use at ISI and at the Naval Ocean Systems Center (NOSC) in the Advanced Command and Control Architectural Testbed (ACCAT) since January 1977. The principal aim of the development effort is the device-independence of the vector graphics. 'Device-independence' means that graphic application programs can be written without regard to the particular display-device on which the output will ultimately be displayed. This system achieves display-device independence by providing the application program with a set of generic, two dimensional vector graphic primitives by which pictures can be described and interacted with at the application level. The particular graphics model used structures pictures as sets of subpictures that are absolute-transformed-segments, as defined by Newman and Sproull.

Bisbey, R., II; Hollingworth, D.

1980-07-01

277

Voltage Control of Three-Stage Hybrid Multilevel Inverter Using Vector Transformation  

Microsoft Academic Search

This paper presents a three-stage 18-level inverter design with a novel control method. The inverter consists of a series-connected main high-voltage, medium-voltage, and low-voltage stages. The high-voltage stage is made of a three-phase, six-switch conventional inverter. The medium- and low-voltage stages are made of three-level inverters constructed by H-bridge units. The proposed control strategy assumes a reference-input voltage vector and

Saad Mekhilef; Mohamad N. Abdul Kadir

2010-01-01

278

Prospects for controlling trypanosomosis.  

PubMed

The best technical package for the future comprises trypanocidal drugs for temporary relief and the use of insecticide-treated cattle, artificial baits and aerial spraying to attack the vector, to so give more lasting security. Whether this can speed the previously slow progress will depend on overcoming past hindrances to tsetse control: sporadic support, disputes over its desirability, difficulties of sustaining international operations, and poor planning in some instances. The Pan-African Tsetse and Trypanosomiasis Campaign intends to speed the progress but will fail unless it improves its image by breaking its association with the sterile insect technique and quickly executing some cheap and effective operations in large areas. Even then, there could be severe brakes due to Africa's political and financial instability. Overall, the pace of control is likely to increase, but perhaps only a little. PMID:19967927

Vale, G A

2009-03-01

279

A model framework to estimate impact and cost of genetics-based sterile insect methods for dengue vector control.  

PubMed

Vector-borne diseases impose enormous health and economic burdens and additional methods to control vector populations are clearly needed. The Sterile Insect Technique (SIT) has been successful against agricultural pests, but is not in large-scale use for suppressing or eliminating mosquito populations. Genetic RIDL technology (Release of Insects carrying a Dominant Lethal) is a proposed modification that involves releasing insects that are homozygous for a repressible dominant lethal genetic construct rather than being sterilized by irradiation, and could potentially overcome some technical difficulties with the conventional SIT technology. Using the arboviral disease dengue as an example, we combine vector population dynamics and epidemiological models to explore the effect of a program of RIDL releases on disease transmission. We use these to derive a preliminary estimate of the potential cost-effectiveness of vector control by applying estimates of the costs of SIT. We predict that this genetic control strategy could eliminate dengue rapidly from a human community, and at lower expense (approximately US$ 2~30 per case averted) than the direct and indirect costs of disease (mean US$ 86-190 per case of dengue). The theoretical framework has wider potential use; by appropriately adapting or replacing each component of the framework (entomological, epidemiological, vector control bio-economics and health economics), it could be applied to other vector-borne diseases or vector control strategies and extended to include other health interventions. PMID:21998654

Alphey, Nina; Alphey, Luke; Bonsall, Michael B

2011-10-05

280

A support vector machine based control application to the experimental three-tank system.  

PubMed

This paper presents a support vector machine (SVM) approach to generalized predictive control (GPC) of multiple-input multiple-output (MIMO) nonlinear systems. The possession of higher generalization potential and at the same time avoidance of getting stuck into the local minima have motivated us to employ SVM algorithms for modeling MIMO systems. Based on the SVM model, detailed and compact formulations for calculating predictions and gradient information, which are used in the computation of the optimal control action, are given in the paper. The proposed MIMO SVM-based GPC method has been verified on an experimental three-tank liquid level control system. Experimental results have shown that the proposed method can handle the control task successfully for different reference trajectories. Moreover, a detailed discussion on data gathering, model selection and effects of the control parameters have been given in this paper. PMID:20417510

Iplikci, Serdar

2010-04-24

281

Simplified Models of Vector Control Impact upon Malaria Transmission by Zoophagic Mosquitoes  

PubMed Central

Background High coverage of personal protection measures that kill mosquitoes dramatically reduce malaria transmission where vector populations depend upon human blood. However, most primary malaria vectors outside of sub-Saharan Africa can be classified as “very zoophagic,” meaning they feed occasionally (<10% of blood meals) upon humans, so personal protection interventions have negligible impact upon their survival. Methods and Findings We extended a published malaria transmission model to examine the relationship between transmission, control, and the baseline proportion of bloodmeals obtained from humans (human blood index). The lower limit of the human blood index enables derivation of simplified models for zoophagic vectors that (1) Rely on only three field-measurable parameters. (2) Predict immediate and delayed (with and without assuming reduced human infectivity, respectively) impacts of personal protection measures upon transmission. (3) Illustrate how appreciable indirect communal-level protection for non-users can be accrued through direct personal protection of users. (4) Suggest the coverage and efficacy thresholds required to attain epidemiological impact. The findings suggest that immediate, indirect, community-wide protection of users and non-users alike may linearly relate to the efficacy of a user’s direct personal protection, regardless of whether that is achieved by killing or repelling mosquitoes. High protective coverage and efficacy (?80%) are important to achieve epidemiologically meaningful impact. Non-users are indirectly protected because the two most common species of human malaria are strict anthroponoses. Therefore, the small proportion of mosquitoes that are killed or diverted while attacking humans can represent a large proportion of those actually transmitting malaria. Conclusions Simplified models of malaria transmission by very zoophagic vectors may be used by control practitioners to predict intervention impact interventions using three field-measurable parameters; the proportion of human exposure to mosquitoes occurring when an intervention can be practically used, its protective efficacy when used, and the proportion of people using it.

Kiware, Samson S.; Chitnis, Nakul; Moore, Sarah J.; Devine, Gregor J.; Majambere, Silas; Merrill, Stephen; Killeen, Gerry F.

2012-01-01

282

Development of fungal applications on netting substrates for malaria vector control.  

PubMed

Mosquito resistance to chemical insecticides is considered a serious threat for the sustainable use of contemporary malaria vector control methods. Fungal entomopathogens show potential as alternative biological control agents against (insecticide-resistant) anophelines. This study was designed to test whether the fungus, Beauveria bassiana, could be delivered to mosquitoes on netting materials that might be used in house screens, such as eave curtains. Tests were conducted to determine effects of formulation, application method, netting material, and nature of mosquito contact. Beauveria had a twice as high impact on Anopheles gambiae s.s. longevity when suspended in Shellsol solvent compared with Ondina oil (HR = 2.12, 95% confidence interval = 1.83-2.60, P < 0.001), and was significantly more infective when applied through spraying than dipping. Polyester and cotton bednets were the most effective substrates for mosquito infections, with highest spore viability on cotton nets. Whereas fungal impact was highest in mosquitoes that had passed through large-meshed impregnated nets, overall efficacy was equal between small- and large-meshed nets, with < or = 30-min spore contact killing >90% of mosquitoes within 10 d. Results indicate that the use of fungal spores dissolved in Shellsol and sprayed on small-meshed cotton eave curtain nets would be the most promising option for field implementation. Biological control with fungus-impregnated eave curtains could provide a means to target host-seeking mosquitoes upon house entry, and has potential for use in integrated vector management strategies, in combination with chemical vector control measures, to supplement malaria control in areas with high levels of insecticide resistance. PMID:21485366

Farenhorst, Marit; Hilhorst, Anne; Thomas, Matthew B; Knols, Bart G J

2011-03-01

283

Tsetse and trypanosomiasis in the Lambwe Valley, Kenya.  

PubMed

The Lambwe Valley is shared between wild animals in a national park and adjacent human settlements with domestic livestock. Thicket and woodland in the valley are heavily infested with Glossina pallidipes. Rhodesian sleeping sickness continues to be a major human health hazard and livestock losses from nagana seriously affect the local economy. Epidemiology is characterized by periods of quiescence and flare-up, reflecting intermittent vector control measures to reduce transmission. The situation has been aggravated in recent years by extension of tsetse habitat and encroachment of settlements to the park. In 1981, an attempt at tsetse eradication by insecticidal methods was unsuccessful, due to technical difficulties and for reasons to do with the resilience of a large, entrenched tsetse population living under environmental optimal conditions. The options for dealing with the disease are outlined, and some of the critical assessments which have to be made are elaborated upon. PMID:3810794

Turner, D A

1986-01-01

284

Options for Field Diagnosis of Human African Trypanosomiasis  

PubMed Central

Human African trypanosomiasis (HAT) due to Trypanosoma brucei gambiense or T. b. rhodesiense remains highly prevalent in several rural areas of sub-Saharan Africa and is lethal if left untreated. Therefore, accurate tools are absolutely required for field diagnosis. For T. b. gambiense HAT, highly sensitive tests are available for serological screening but the sensitivity of parasitological confirmatory tests remains insufficient and needs to be improved. Screening for T. b. rhodesiense infection still relies on clinical features in the absence of serological tests available for field use. Ongoing research is opening perspectives for a new generation of field diagnostics. Also essential for both forms of HAT is accurate determination of the disease stage because of the high toxicity of melarsoprol, the drug most widely used during the neurological stage of the illness. Recent studies have confirmed the high accuracy of raised immunoglobulin M levels in the cerebrospinal fluid for the staging of T. b. gambiense HAT, and a promising simple assay (LATEX/IgM) is being tested in the field. Apart from the urgent need for better tools for the field diagnosis of this neglected disease, improved access to diagnosis and treatment for the population at risk remains the greatest challenge for the coming years.

Chappuis, Francois; Loutan, Louis; Simarro, Pere; Lejon, Veerle; Buscher, Philippe

2005-01-01

285

Theory and simulation of vector control based on rotor position orientation of rare-earth permanent magnet motor  

Microsoft Academic Search

Since the rare-earth permanent materials were invented, all kinds of PM motors and their relevant control methods have been booming. Requirements on high efficiency and flexible control systems are the core of its development. Vector control method based on rotor position orientation of rare-earth PM is presented under this case, and it has so many control qualifies that general DC

Yong Zhang; Keran Shao; Lan Li; Xinhua Li

2003-01-01

286

Effect of Artemether-Lumefantrine Policy and Improved Vector Control on Malaria Burden in KwaZulu–Natal, South Africa  

Microsoft Academic Search

BackgroundBetween 1995 and 2000, KwaZulu–Natal province, South Africa, experienced a marked increase in Plasmodium falciparum malaria, fuelled by pyrethroid and sulfadoxine-pyrimethamine resistance. In response, vector control was strengthened and artemether-lumefantrine (AL) was deployed in the first Ministry of Health artemisinin-based combination treatment policy in Africa. In South Africa, effective vector and parasite control had historically ensured low-intensity malaria transmission. Malaria

Karen I. Barnes; David N. Durrheim; Francesca Little; Amanda Jackson; Ushma Mehta; Elizabeth Allen; Sicelo S. Dlamini; Joyce Tsoka; Barry Bredenkamp; D. Jotham Mthembu; Nicholas J. White; Brian L. Sharp

2005-01-01

287

Fuzzy logic control of a space-vector PWM current regulator for three-phase power converters  

Microsoft Academic Search

This paper presents a fuzzy logic implementation of space-vector pulse-width modulation (PWM) for three-phase power converters. The conventional space-vector PWM current regulator implementation is generally computationally complex. The fuzzy logic controller implementation relieves the processor of a number of computations, thereby accommodating a less expensive microprocessor. The AC-side rectifier voltages are used as fuzzy-state variables. The fuzzy logic control has

Suttichai Saetieo; David A. Torrey

1998-01-01

288

Construction of two Lactococcus lactis expression vectors combining the Gateway and the NIsin Controlled Expression systems.  

PubMed

Over the last 10 years, the NIsin Controlled Expression (NICE) system has been extensively used in the food-grade bacterium Lactococcus lactis subsp. cremoris to produce homologous and heterologous proteins for academic and biotechnological purposes. Although various L. lactis molecular tools have been developed, no expression vectors harboring the popular Gateway recombination system are currently available for this widely used cloning host. In this study, we constructed two expression vectors that combine the NICE and the Gateway recombination systems and we tested their applicability by recombining and over-expressing genes encoding structural proteins of lactococcal phages Tuc2009 and TP901-1. Over-expressed phage proteins were analyzed by immunoblotting and purified by His-tag affinity chromatography with protein productions yielding 2.8-3.7 mg/l of culture. This therefore is the first description of L. lactis NICE expression vectors which integrate the Gateway cloning technology and which are suitable for the production of sufficient amounts of proteins to facilitate subsequent structural and functional analyses. PMID:21807023

Douillard, François P; Mahony, Jennifer; Campanacci, Valérie; Cambillau, Christian; van Sinderen, Douwe

2011-07-23

289

American trypanosomiasis infection in fattening pigs from the south-east of Mexico.  

PubMed

American Trypanosomiasis (AT) is an infectious parasitic disease produced by the protozoa Trypanosoma cruzi (T. cruzi). Infection is acquired by vectorial via but can also be transmitted congenitally, by ingestion of an infected host, by transfusion with contaminated blood or transplant of organs from an infected donor. Currently, AT is widely distributed from the South of the United States to South America. In Mexico, the presence of the parasite has been reported throughout the country where several reservoirs such as dogs, opossums, rats and cats have been identified. Yucatan is in the south-east of Mexico where AT is endemic and has been reported since 1940s. There is little information about the role of pigs as reservoirs of T. cruzi. The frequency of specific antibodies against T. cruzi was determined in fattening pigs from Yucatan, Mexico. After sampling in the 3 main areas of pig production in the state, IgG ELISA and Western blot were performed to identify seropositive cases. Association of farm size, farm area and production system with infected pigs was evaluated. From 273 sampled pigs, 5.4% (n = 15) positive cases were found. No association with evaluated factors and infected pigs was found. Pigs are also reservoirs of T. cruzi in the studied area. These findings are considered important to improve vectorial control in the area in order to avoid the parasite infection in animal populations destined for human consumption and avoid further transmission to humans. PMID:22958261

Jiménez-Coello, M; Acosta-Viana, K Y; Guzman-Marin, E; Ortega-Pacheco, A

2012-09-01

290

Update on field use of the available drugs for the chemotherapy of human African trypanosomiasis.  

PubMed

Despite the fact that eflornithine was considered as the safer drug to treat human African trypanosomiasis (HAT) and has been freely available since 2001, the difficulties in logistics and cost burden associated with this drug meant that the toxic melarsoprol remained the drug of choice. The World Health Organization responded to the situation by designing a medical kit containing all the materials needed to use eflornithine, and by implementing a training and drugs distribution programme which has allowed a transition to this much safer treatment. The introduction of the combination of nifurtimox and eflornithine (NECT) has accelerated the shift from melarsoprol to the best treatment available, due to reduced dosage and treatment time for eflornithine that has significantly lessened the cost and improved the burden of logistics encountered during treatment and distribution. The decrease in the use of more dangerous but cheaper melarsoprol has meant a rise in the per patient cost of treating HAT. Although NECT is cheaper than eflornithine monotherapy, an unexpected consequence has been a continuing rise in the per patient cost of treating HAT. The ethical decision of shifting to the best available treatment imposes a financial burden on HAT control programmes that might render long-term application unsustainable. These factors call for continuing research to provide new safer and more effective drugs that are simple to administer and cheaper when compared to current drugs. PMID:22309684

Simarro, P P; Franco, J; Diarra, A; Postigo, J A Ruiz; Jannin, J

2012-02-06

291

Oviposition Site Selection by the Dengue Vector Aedes aegypti and Its Implications for Dengue Control  

PubMed Central

Background Because no dengue vaccine or antiviral therapy is commercially available, controlling the primary mosquito vector, Aedes aegypti, is currently the only means to prevent dengue outbreaks. Traditional models of Ae. aegypti assume that population dynamics are regulated by density-dependent larval competition for food and little affected by oviposition behavior. Due to direct impacts on offspring survival and development, however, mosquito choice in oviposition site can have important consequences for population regulation that should be taken into account when designing vector control programs. Methodology/Principal Findings We examined oviposition patterns by Ae. aegypti among 591 naturally occurring containers and a set of experimental containers in Iquitos, Peru. Using larval starvation bioassays as an indirect measure of container food content, we assessed whether females select containers with the most food for their offspring. Our data indicate that choice of egg-laying site is influenced by conspecific larvae and pupae, container fill method, container size, lid, and sun exposure. Although larval food positively influenced oviposition, our results did not support the hypothesis that females act primarily to maximize food for larvae. Females were most strongly attracted to sites containing immature conspecifics, even when potential competitors for their progeny were present in abundance. Conclusion/Significance Due to strong conspecific attraction, egg-laying behavior may contribute more to regulating Ae. aegypti populations than previously thought. If highly infested containers are targeted for removal or larvicide application, females that would have preferentially oviposited in those sites may instead distribute their eggs among other suitable, previously unoccupied containers. Strategies that kill mosquitoes late in their development (i.e., insect growth regulators that kill pupae rather than larvae) will enhance vector control by creating “egg sinks,” treated sites that exploit conspecific attraction of ovipositing females, but reduce emergence of adult mosquitoes via density-dependent larval competition and late acting insecticide.

Wong, Jacklyn; Stoddard, Steven T.; Astete, Helvio; Morrison, Amy C.; Scott, Thomas W.

2011-01-01

292

A Pulsewidth Modulated Control of Induction Motor Drive Using Multilevel 12-Sided Polygonal Voltage Space Vectors  

Microsoft Academic Search

In this paper, a novel 12-sided polygonal space vector structure is proposed for an induction motor drive. The space vector pattern presented in this paper consists of two 12-sided concentric polygons with the outer polygon having a radius double the inner one. As compared to previously reported 12-sided polygonal space vector structures, this paper subdivides the space vector plane into

Anandarup Das; K. Sivakumar; Rijil Ramchand; Chintan Patel; K. Gopakumar

2009-01-01

293

Malaria vector control by indoor residual insecticide spraying on the tropical island of Bioko, Equatorial Guinea  

PubMed Central

Background A comprehensive malaria control intervention was initiated in February 2004 on Bioko Island, Equatorial Guinea. This manuscript reports on the continuous entomological monitoring of the indoor residual spray (IRS) programme during the first two years of its implementation. Methods Mosquitoes were captured daily using window traps at 16 sentinel sites and analysed for species identification, sporozoite rates and knockdown resistance (kdr) using polymerase chain reaction (PCR) to assess the efficacy of the vector control initiative from December 2003 to December 2005. Results A total of 2,807 and 10,293 Anopheles funestus and Anopheles gambiae s.l. respectively were captured throughout the study period. Both M and S molecular forms of An. gambiae s.s. and Anopheles melas were identified. Prior to the first round of IRS, sporozoite rates were 6.0, 8.3 and 4.0 for An. gambiae s.s., An. melas and An. funestus respectively showing An. melas to be an important vector in areas in which it occurred. After the third spray round, no infective mosquitoes were identified. After the first spray round using a pyrethroid spray the number of An. gambiae s.s. were not reduced due to the presence of the kdr gene but An funestus and An. melas populations declined from 23.5 to 3.1 and 5.3 to 0.8 per trap per 100 nights respectively. After the introduction of a carbamate insecticide in the second round, An. gambiae s.s. reduced from 25.5 to 1.9 per trap per 100 nights and An. funestus and An. melas remained at very low levels. Kdr was found only in the M-form of An. gambiae s.s. with the highest frequency at Punta Europa (85%). Conclusion All three vectors that were responsible for malaria transmission before the start of the intervention were successfully controlled once an effective insecticide was used. Continuous entomological surveillance including resistance monitoring is of critical importance in any IRS based malaria vector control programme. This paper demonstrates that sufficient resources for such monitoring should be included in any proposal in order to avoid programme failures.

Sharp, Brian L; Ridl, Frances C; Govender, Dayanandan; Kuklinski, Jaime; Kleinschmidt, Immo

2007-01-01

294

The potential of a new larviciding method for the control of malaria vectors.  

PubMed

Malaria pathogens are transmitted to humans by the bite of female Anopheles mosquitoes. The juvenile stages of these mosquitoes develop in a variety of water bodies and are key targets for vector control campaigns involving the application of larvicides. The effective operational implementation of these campaigns is difficult, time consuming, and expensive. New evidence however, suggests that adult mosquitoes can be co-opted into disseminating larvicides in a far more targeted and efficient manner than can be achieved using conventional methods. PMID:20500865

Devine, Gregor J; Killeen, Gerry F

2010-05-25

295

Modelling the impact of vector control interventions on Anopheles gambiae population dynamics  

PubMed Central

Background Intensive anti-malaria campaigns targeting the Anopheles population have demonstrated substantial reductions in adult mosquito density. Understanding the population dynamics of Anopheles mosquitoes throughout their whole lifecycle is important to assess the likely impact of vector control interventions alone and in combination as well as to aid the design of novel interventions. Methods An ecological model of Anopheles gambiae sensu lato populations incorporating a rainfall-dependent carrying capacity and density-dependent regulation of mosquito larvae in breeding sites is developed. The model is fitted to adult mosquito catch and rainfall data from 8 villages in the Garki District of Nigeria (the 'Garki Project') using Bayesian Markov Chain Monte Carlo methods and prior estimates of parameters derived from the literature. The model is used to compare the impact of vector control interventions directed against adult mosquito stages - long-lasting insecticide treated nets (LLIN), indoor residual spraying (IRS) - and directed against aquatic mosquito stages, alone and in combination on adult mosquito density. Results A model in which density-dependent regulation occurs in the larval stages via a linear association between larval density and larval death rates provided a good fit to seasonal adult mosquito catches. The effective mosquito reproduction number in the presence of density-dependent regulation is dependent on seasonal rainfall patterns and peaks at the start of the rainy season. In addition to killing adult mosquitoes during the extrinsic incubation period, LLINs and IRS also result in less eggs being oviposited in breeding sites leading to further reductions in adult mosquito density. Combining interventions such as the application of larvicidal or pupacidal agents that target the aquatic stages of the mosquito lifecycle with LLINs or IRS can lead to substantial reductions in adult mosquito density. Conclusions Density-dependent regulation of anopheline larvae in breeding sites ensures robust, stable mosquito populations that can persist in the face of intensive vector control interventions. Selecting combinations of interventions that target different stages in the vector's lifecycle will result in maximum reductions in mosquito density.

2011-01-01

296

Investigation of modal interaction and its effects on control performance in stressed power systems using normal forms of vector fields  

Microsoft Academic Search

This paper presents a systematic scheme to evaluate nonlinear modal interaction in a power system with excitation control and determine the effect of the interaction on control performance using the normal forms of vectors fields. The proposed approach has been applied to a two-area, four-generator system. The results obtained showed that the control modes have significant interaction with the inertial

Chih-Ming Lin; V. Vittal; W. Kliemann; A. A. Fouad

1996-01-01

297

Studying fitness cost of Plasmodium falciparum infection in malaria vectors: validation of an appropriate negative control  

PubMed Central

Background The question whether Plasmodium falciparum infection affects the fitness of mosquito vectors remains open. A hurdle for resolving this question is the lack of appropriate control, non-infected mosquitoes that can be compared to the infected ones. It was shown recently that heating P. falciparum gametocyte-infected blood before feeding by malaria vectors inhibits the infection. Therefore, the same source of gametocyte-infected blood could be divided in two parts, one heated, serving as the control, the other unheated, allowing the comparison of infected and uninfected mosquitoes which fed on exactly the same blood otherwise. However, before using this method for characterizing the cost of infection to mosquitoes, it is necessary to establish whether feeding on previously heated blood affects the survival and fecundity of mosquito females. Methods Anopheles gambiae M molecular form females were exposed to heated versus non-heated, parasite-free human blood to mimic blood meal on non-infectious versus infectious gametocyte-containing blood. Life history traits of mosquito females fed on blood that was heat-treated or not were then compared. Results The results reveal that heat treatment of the blood did not affect the survival and fecundity of mosquito females. Consistently, blood heat treatment did not affect the quantity of blood ingested. Conclusions The study indicates that heat inactivation of gametocyte-infected blood will only inhibit mosquito infection and that this method is suitable for quantifying the fitness cost incurred by mosquitoes upon infection by P. falciparum.

2013-01-01

298

Evaluation of New Tools for Malaria Vector Control in Cameroon: Focus on Long Lasting Insecticidal Nets  

PubMed Central

Background From 2006 to 2011, biological activity of insecticides for Indoor Residual Spraying (IRS), conventional treatment of nets (CTNs) or long lasting insecticidal nets (LLINs) was evaluated before their approval in Cameroon. The objective of the study was to select the best tools for universal malaria vector control coverage. Methodology Bioassays were performed using WHO cones and the Kisumu susceptible strain of Anopheles gambiae s.s.. Among tested products, residual activity and wash resistance of Alpha-cypermethrin LLINs (Interceptor) and CTNs (Fendona) were assessed during 5 months in the Ntougou neighborhood. Principal Findings All the 14 tested products were found effective (95–100% knockdown and mortality rates), although a significant decrease of efficacy was seen with lambda-cyhalothrinWP IRS, alpha-cypermethrin CTNs and LLINs (p< 0.05). However, the efficacy of Interceptor nets did not decrease during the 5 months evaluation, even after 25 washes (0.07vector control in Cameroon.

Etang, Josiane; Nwane, Philippe; Piameu, Michael; Manga, Blaise; Souop, Daniel; Awono-Ambene, Parfait

2013-01-01

299

Proteomic Selection of Immunodiagnostic Antigens for Human African Trypanosomiasis and Generation of a Prototype Lateral Flow Immunodiagnostic Device  

PubMed Central

Background The diagnosis of Human African Trypanosomiasis relies mainly on the Card Agglutination Test for Trypanosomiasis (CATT). While this test is successful, it is acknowledged that there may be room for improvement. Our aim was to develop a prototype lateral flow test based on the detection of antibodies to trypanosome antigens. Methodology/Principal Findings We took a non-biased approach to identify potential immunodiagnostic parasite protein antigens. The IgG fractions from the sera from Trypanosoma brucei gambiense infected and control patients were isolated using protein-G affinity chromatography and then immobilized on Sepharose beads. The IgG-beads were incubated with detergent lysates of trypanosomes and those proteins that bound were identified by mass spectrometry-based proteomic methods. This approach provided a list of twenty-four trypanosome proteins that selectively bound to the infection IgG fraction and that might, therefore, be considered as immunodiagnostic antigens. We selected four antigens from this list (ISG64, ISG65, ISG75 and GRESAG4) and performed protein expression trials in E. coli with twelve constructs. Seven soluble recombinant protein products (three for ISG64, two for ISG65 and one each for ISG75 and GRESAG4) were obtained and assessed for their immunodiagnostic potential by ELISA using individual and/or pooled patient sera. The ISG65 and ISG64 construct ELISAs performed well with respect to detecting T. b. gambiense infections, though less well for detecting T. b. rhodesiense infections, and the best performing ISG65 construct was used to develop a prototype lateral flow diagnostic device. Conclusions/Significance Using a panel of eighty randomized T. b. gambiense infection and control sera, the prototype showed reasonable sensitivity (88%) and specificity (93%) using visual readout in detecting T. b. gambiense infections. These results provide encouragement to further develop and optimize the lateral flow device for clinical use.

Sullivan, Lauren; Wall, Steven J.; Carrington, Mark; Ferguson, Michael A. J.

2013-01-01

300

Tightly regulated, high-level expression from controlled copy number vectors based on the replicon of temperate phage N15  

Microsoft Academic Search

A new Escherichia coli host\\/vector system has been developed to allow a dual regulation of both the plasmid copy number and gene expression. The new pN15E vectors are low copy number plasmids based on the replicon of temperate phage N15, comprising the repA replicase gene and cB repressor gene, controlling the plasmid copy number. Regulation of pN15E copy number is

Andrey V. Mardanov; Taisia S. Strakhova; Vladimir A. Smagin; Nikolai V. Ravin

2007-01-01

301

Insecticide resistance and malaria vector control: the importance of fitness cost mechanisms in determining economically optimal control trajectories.  

PubMed

The evolutionary dynamics of insecticide resistance in harmful arthropods has economic implications, not only for the control of agricultural pests (as has been well studied), but also for the control of disease vectors, such as malaria-transmitting Anopheles mosquitoes. Previous economic work on insecticide resistance illustrates the policy relevance of knowing whether insecticide resistance mutations involve fitness costs. Using a theoretical model, this article investigates economically optimal strategies for controlling malaria-transmitting mosquitoes when there is the potential for mosquitoes to evolve resistance to insecticides. Consistent with previous literature, we find that fitness costs are a key element in the computation of economically optimal resistance management strategies. Additionally, our models indicate that different biological mechanisms underlying these fitness costs (e.g., increased adult mortality and/or decreased fecundity) can significantly alter economically optimal resistance management strategies. PMID:23448053

Brown, Zachary S; Dickinson, Katherine L; Kramer, Randall A

2013-02-01

302

A neural network based speed control design strategy of an indirect vector controlled induction machine drive  

Microsoft Academic Search

Artificial neural networks (ANN) have the capacity to learn the characteristics of a nonlinear system through nonlinear mappings. They are then potential candidates for highly nonlinear dynamical processes control. In this paper, a neural network controller design for speed adjustment of an indirect field oriented induction machine drive is considered. An original PI based controller is first proposed. Its simulated

A. Miloudi; Y. Miloud; A. Draou

2003-01-01

303

Malaria transmission after five years of vector control on Bioko Island, Equatorial Guinea  

PubMed Central

Background Malaria is endemic with year-round transmission on Bioko Island. The Bioko Island Malaria Control Project (BIMCP) started in 2004 with the aim to reduce malaria transmission and to ultimately eliminate malaria. While the project has been successful in reducing overall malaria morbidity and mortality, foci of high malaria transmission still persist on the island. Results from the 2009 entomological collections are reported here. Methods Human landing collections (HLC) and light trap collections (LTC) were carried out on Bioko Island, Equatorial Guinea in 2009. The HLCs were performed in three locations every second month and LTCs were carried out in 10 locations every second week. Molecular analyses were performed to identify species, detect sporozoites, and identify potential insecticide resistance alleles. Results The entomological inoculation rates (EIR) on Bioko Island ranged from 163 to 840, with the outdoor EIRs reaching > 900 infective mosquito bites per year. All three human landing collection sites on Bioko Island had an annual EIR exceeding the calculated African average of 121 infective bites per year. The highest recorded EIRs were in Punta Europa in northwestern Bioko Island with human biting rates of 92 and 66 mosquito landings per person per night, outdoors and indoors, respectively. Overall, the propensity for mosquito biting on the island was significantly higher outdoors than indoors (p < 0.001). Both Anopheles gambiae s.s. and An. melas were responsible for malaria transmission on the island, but with different geographical distribution patterns. Sporozoite rates were the highest in An. gambiae s.s. populations ranging from 3.1% in Punta Europa and 5.7% in Riaba in the southeast. Only the L1014F (kdr-west) insecticide resistance mutation was detected on the island with frequencies ranging from 22-88% in An. gambiae s.s. No insecticide resistance alleles were detected in the An. melas populations. Conclusions In spite of five years of extensive malaria control and a generalized reduction in the force of transmission, parasite prevalence and child mortality, foci of very high transmission persist on Bioko Island, particularly in the northwestern Punta Europa area. This area is favorable for anopheline mosquito breeding; human biting rates are high, and the EIRs are among the highest ever recorded. Both vector species collected in the study have a propensity to bite outdoors more frequently than indoors. Despite current vector control efforts mosquito densities remain high in such foci of high malaria transmission. To further reduce transmission, indoor residual spraying (IRS) needs to be supplemented with additional vector control interventions.

2012-01-01

304

Plant extracts, isolated phytochemicals, and plant-derived agents which are lethal to arthropod vectors of human tropical diseases--a review.  

PubMed

The recent scientific literature on plant-derived agents with potential or effective use in the control of the arthropod vectors of human tropical diseases is reviewed. Arthropod-borne tropical diseases include: amebiasis, Chagas disease (American trypanosomiasis), cholera, cryptosporidiosis, dengue (hemorrhagic fever), epidemic typhus (Brill-Zinsser disease), filariasis (elephantiasis), giardia (giardiasis), human African trypanosomiasis (sleeping sickness), isosporiasis, leishmaniasis, Lyme disease (lyme borreliosis), malaria, onchocerciasis, plague, recurrent fever, sarcocystosis, scabies (mites as causal agents), spotted fever, toxoplasmosis, West Nile fever, and yellow fever. Thus, coverage was given to work describing plant-derived extracts, essential oils (EOs), and isolated chemicals with toxic or noxious effects on filth bugs (mechanical vectors), such as common houseflies (Musca domestica Linnaeus), American and German cockroaches (Periplaneta americana Linnaeus, Blatella germanica Linnaeus), and oriental latrine/blowflies (Chrysomya megacephala Fabricius) as well as biting, blood-sucking arthropods such as blackflies (Simulium Latreille spp.), fleas (Xenopsylla cheopis Rothschild), kissing bugs (Rhodnius Stål spp., Triatoma infestans Klug), body and head lice (Pediculus humanus humanus Linnaeus, P. humanus capitis De Geer), mosquitoes (Aedes Meigen, Anopheles Meigen, Culex L., and Ochlerotatus Lynch Arribálzaga spp.), sandflies (Lutzomyia longipalpis Lutz & Neiva, Phlebotomus Loew spp.), scabies mites (Sarcoptes scabiei De Geer, S. scabiei var hominis, S. scabiei var canis, S. scabiei var suis), and ticks (Ixodes Latreille, Amblyomma Koch, Dermacentor Koch, and Rhipicephalus Koch spp.). Examples of plant extracts, EOs, and isolated chemicals exhibiting noxious or toxic activity comparable or superior to the synthetic control agents of choice (pyrethroids, organophosphorous compounds, etc.) are provided in the text for many arthropod vectors of tropical diseases. PMID:21432748

Pohlit, Adrian Martin; Rezende, Alex Ribeiro; Lopes Baldin, Edson Luiz; Lopes, Norberto Peporine; Neto, Valter Ferreira de Andrade

2011-03-22

305

Scientists and public involvement: a consultation on the relation between malaria, vector control and transgenic mosquitoes.  

PubMed

Among the hopes for vector-based malaria control, the use of transgenic mosquitoes able to kill malaria parasites is seen as a potential way to interrupt malaria transmission. While this potential solution is gaining some support, the ethical and social aspects related to this high-tech method remain largely unexplored and underestimated. Related to those latter points, the aim of the present survey is to determine how scientists working on malaria and its vector mosquitoes perceive public opinion and how they evaluate public consultations on their research. This study has been performed through a questionnaire addressing questions related to the type of research, the location, the nationality and the perception of the public involvement by scientists. The results suggest that even if malaria researchers agree to interact with a non-scientific audience, they (especially the ones from the global North) remain quite reluctant to have their research project submitted in a jargon-free version to the evaluation and the prior-agreement by a group of non-specialists. The study, by interrogating the links between the scientific community and the public from the perspective of the scientists, reveals the importance of fostering structures and processes that could lead to a better involvement of a non specialist public in the actual debates linking scientific, technological and public health issues in Africa. PMID:21955738

Boëte, Christophe

2011-09-28

306

Chagas disease vector control through different intervention modalities in endemic localities of Paraguay.  

PubMed Central

In a field study carried out in three rural communities in Paraguay in a zone endemic for Chagas disease, we implemented three different vector control interventions--spraying, housing improvement, and a combination of spraying plus housing improvement--which effectively reduced the triatomine infestation. The reduction of triatomine infestation was 100% (47/47) in the combined intervention community, whereas in the community where housing improvement was carried out it was 96.4% (53/55). In the community where fumigation alone was used, the impact was 97.6% (40/41) in terms of domiciliary infestation. In all the houses where an intervention was made, an 18-month follow-up showed reinfestation rates of less than 10%. A serological survey of the population in the pre- and post-intervention periods revealed a shift in positive cases towards older age groups, but no significant differences were observed. The rate of seroconversion was 1.3% (three new cases) in the community with housing improvement only, but none of these cases could have resulted from vector transmission. The most cost-effective intervention was insecticide spraying, which during a 21-month follow-up period had a high impact on triatomine infestation and cost US$ 29 per house as opposed to US$ 700 per house for housing improvement.

Rojas de Arias, A.; Ferro, E. A.; Ferreira, M. E.; Simancas, L. C.

1999-01-01

307

Glossina fuscipes fuscipes in the trypanosomiasis endemic areas of south eastern Uganda: apparent density, trypanosome infection rates and host feeding preferences.  

PubMed

A study was undertaken in three districts in south eastern Uganda endemic for human and animal trypanosomiasis, to investigate the status of the vector tsetse fly population. Apparent density (AD) of tsetse was between 2 and 21 flies/trap/day across the three districts, with Glossinia fuscipes fuscipes identified as the predominant species. Trypanosomes were observed in G.f. fuscipes with an infection rate, as determined by microscopy, of 1.55% across the three studied areas. However, trypanosome infections were only identified in female flies giving an infection rate of 2.39% for the female tsetse when this sex was considered in isolation; no male flies were found to be infected. Bloodmeal analysis highlighted 3 principal vertebrate hosts, namely cattle, pigs and monitor lizards (Varanus niloticus). The implication of this, in relation to the cycle of transmission for human infective trypanosomes between domestic animals and man, is discussed. PMID:16870129

Waiswa, C; Picozzi, K; Katunguka-Rwakishaya, E; Olaho-Mukani, W; Musoke, R A; Welburn, S C

2006-07-25

308

Sensorless Vector Control of the Charging Process for Flywheel Battery with Artificial Neural Network Observer  

NASA Astrophysics Data System (ADS)

The new type of flywheel battery requires control system with compact structure and low manufacturing cost. To meet this requirement, a new method for the sensorless vector control of flywheel battery is proposed in this paper. The advantage of the proposed control system is that it does not need an extra sensor to obtain the flywheel speed and position information. The determination of flywheel position and thereby speed are made by estimating back electromotive force (EMF) using the artificial neural network (ANN) observers. By doing so, the dimensions and cost of the driver system can be reduced. The ANN observers use the instantaneous values of stator voltages and currents and the estimated error of the stator current as their input to output the back EMF components in the ?-? reference frame. A simulation model was established by the use of MATLAB/Simulink software to carry out the numerical experiments. The test results demonstrate that the proposed charging control system for flywheel battery has a good control performance and a good robustness. The speed /position estimation precision is high and the error is acceptable for a wide speed range.

Qin, Honglin; Huang, Meng; Li, Zhixiong; Tang, Shuangqing

309

Comparison of rotor flux and reactive power based MRAS rotor resistance estimators for Vector Controlled Induction Motor drive  

Microsoft Academic Search

In this paper, a detailed study of the performance of rotor flux and reactive power based MRAS rotor resistance estimators for Vector Controlled Induction Motor drive is presented. The rotor resistance changes significantly during operation of the drive due to temperature rise and saturation. This variation has a major influence on the performance of the field oriented control of induction

M. Nandhini Gayathri; S. Himavathi; R. Sankaran

2012-01-01

310

PI and fuzzy estimators for on-line tracking of rotor resistance of indirect vector controlled induction motor drive  

Microsoft Academic Search

This paper presents two methods of estimation of the rotor resistance in the indirect vector controlled induction motor drive. A model reference adaptive scheme is proposed in which the adaptation mechanism is executed using a PI controller and a fuzzy logic. The performance of both estimators and torque and flux responses of the drive are investigated with simulations for variations

B. Karanayil; M. F. Rahman; C. Grantham

2001-01-01

311

Application of an extended Kalman filter to rotor speed and resistance estimation in induction motor vector control  

Microsoft Academic Search

The vector control method allows high performance control of torque and speed to be achieved from an induction machine. The decoupling of the flux and the electromagnetic torque, obtained by field orientation, depends on the precision and the accuracy of the estimated states. This paper presents the application of the extended Kalman filter (EKF) to the online estimation of the

M. A. Ouhrouche; S. Lefebvre; X. D. Do

1998-01-01

312

A maximum torque per ampere vector control strategy for synchronous reluctance motors considering saturation and iron losses  

Microsoft Academic Search

In recent years, the synchronous reluctance (SyncRel) motor received much attention for many applications due to its simple and robust construction. When using the principle of vector control, it is possible to achieve optimal operation of SyncRel motors for all loads and speeds. A suitable control strategy can be implemented to achieve maximum torque per ampere, high efficiency and maximum

E. M. Rashad; T. S. Radwan; M. A. Rahman

2004-01-01

313

Research on energy saving control scheme of elevator running based upon the current angle &thetas; in vector space  

Microsoft Academic Search

This article introduces an energy saving control scheme of elevator running based upon the current angle ? in vector space, and the proof of the stator current minimization algorithm is presented. This control scheme does not increase the systematic hardware cost. Through adjusting magnetizing current according to the motor load, the stator current is minimized, thus minimum motor loss is

Ding Bao; Sun Manyi; Tang Haiyan

2005-01-01

314

Estimating dengue vector abundance in the wet and dry season: implications for targeted vector control in urban and peri-urban Asia  

PubMed Central

Background: Research has shown that the classical Stegomyia indices (or “larval indices”) of the dengue vector Aedes aegypti reflect the absence or presence of the vector but do not provide accurate measures of adult mosquito density. In contrast, pupal indices as collected in pupal productivity surveys are a much better proxy indicator for adult vector abundance. However, it is unknown when it is most optimal to conduct pupal productivity surveys, in the wet or in the dry season or in both, to inform control services about the most productive water container types and if this pattern varies among different ecological settings. Methods: A multi-country study in randomly selected twelve to twenty urban and peri-urban neighborhoods (“clusters”) of six Asian countries, in which all water holding containers were examined for larvae and pupae of Aedes aegypti during the dry season and the wet season and their productivity was characterized by water container types. In addition, meteorological data and information on reported dengue cases were collected. Findings: The study reconfirmed the association between rainfall and dengue cases (“dengue season”) and underlined the importance of determining through pupal productivity surveys the “most productive containers types”, responsible for the majority (>70%) of adult dengue vectors. The variety of productive container types was greater during the wet than during the dry season, but included practically all container types productive in the dry season. Container types producing pupae were usually different from those infested by larvae indicating that containers with larval infestations do not necessarily foster pupal development and thus the production of adult Aedes mosquitoes. Conclusion: Pupal productivity surveys conducted during the wet season will identify almost all of the most productive container types for both the dry and wet seasons and will therefore facilitate cost-effective targeted interventions.

Wai, Khin Thet; Arunachalam, Natarajan; Tana, Susilowati; Espino, Fe; Kittayapong, Pattamaporn; Abeyewickreme, W; Hapangama, Dilini; Tyagi, Brij Kishore; Htun, Pe Than; Koyadun, Surachart; Kroeger, Axel; Sommerfeld, Johannes; Petzold, Max

2012-01-01

315

Indigenous knowledge system for treatment of trypanosomiasis in Kaduna state of Nigeria  

Microsoft Academic Search

A survey was carried out in Kaduna State of Nigeria to establish the indigenous knowledge system for treating trypanosomiasis in domestic animals. Questionnaire and interviews were, respectively, administered to, or conducted with about 200 livestock farmers and traders spread around the state. Data obtained revealed the use of several plants either alone or in combination, for the treatment and management

S. E Atawodi; D. A Ameh; S Ibrahim; J. N Andrew; H. C Nzelibe; E. O Onyike; K. M Anigo; E. A Abu; D. B James; G. C Njoku; A. B Sallau

2002-01-01

316

Glycogen Synthase Kinase 3 Is a Potential Drug Target for African Trypanosomiasis Therapy  

Microsoft Academic Search

Development of a safe, effective, and inexpensive therapy for African trypanosomiasis is an urgent priority. In this study, we evaluated the validity of Trypanosoma brucei glycogen synthase kinase 3 (GSK-3) as a potential drug target. Interference with the RNA of either of two GSK-3 homologues in bloodstream-form T. brucei parasites led to growth arrest and altered parasite morphology, demonstrating their

Kayode K. Ojo; J. Robert Gillespie; Aaron J. Riechers; Alberto J. Napuli; Christophe L. M. J. Verlinde; Frederick S. Buckner; Michael H. Gelb; Mathias M. Domostoj; Susan J. Wells; Alexander Scheer; Timothy N. C. Wells; Wesley C. Van Voorhis

2008-01-01

317

Use of polymerase chain reaction in human African trypanosomiasis stage determination and follow-up  

Microsoft Academic Search

Stage determination of human African trypanosomiasis is based on the detection of parasites and measurements of biological changes in the cerebrospinal fluid (CSF) (concentration of white blood cells > 5 cells per mm3 and increased total protein levels). The patient is treated accordingly. Demonstration of the absence or presence of trypanosomes by the double centrifugation technique is still the only

P. Truc; V. Jamonneau; G. Cuny; J. L. Frezil

318

HUMAN TRYPANOSOMIASIS CAUSED BY TRYPANOSOMA EVANSI IN INDIA: THE FIRST CASE REPORT  

Microsoft Academic Search

We report an Indian farmer who had fluctuating trypanosome parasitemia associated with febrile episodes for five months. Morphologic examination of the parasites indicated the presence of large numbers of trypanosomes belonging to the species Trypanosoma evansi, which is normally a causative agent of animal trypanosomiasis known as surra. Basic clinical and biologic examinations are described, using several assays, including parasitologic,

PRASHANT P. JOSHI; VIJAY R. SHEGOKAR; RAJARAM M. POWAR; STEPHANE HERDER; RAHUL KATTI; HARSHA R. SALKAR; VIBHAWARI S. DANI; ARADHANA BHARGAVA; JEAN JANNIN; PHILIPPE TRUC

319

Association between human African trypanosomiasis and the IL6 gene in a Congolese population  

Microsoft Academic Search

Despite the importance of behavioural and environmental risk factors, there are arguments consistent with the existence of a genetic susceptibility to human African trypanosomiasis (HAT). A candidate gene association study was conducted in the Democratic Republic of Congo using a family-based sample which included a total of 353 subjects (86 trios; one case and parents (n=258) and 23 families with

David Courtin; Jacqueline Milet; Vincent Jamonneau; Claude Sese Yeminanga; Victor Kande Betu Kumeso; Constantin Miaka Mia Bilengue; Christine Betard; André Garcia

2007-01-01

320

Different mosquito species host Wickerhamomyces anomalus (Pichia anomala): perspectives on vector-borne diseases symbiotic control.  

PubMed

The genetic manipulation of the microbial community associated with hematophagus insects is particularly relevant for public health applications. Within mosquito populations, this relationship has been overlooked until recently. New advances in molecular biotechnology propose the genetic manipulation of mosquito symbionts to prevent the transmission of pathogens to humans by interfering with the obligatory life cycle stages within the insect through the use of effector molecules. This approach, defined as 'paratransgenesis', has opened the way for the investigation and characterization of microbes residing in the mosquito body, particularly those localised within the gut. Some interesting bacteria have been identified as candidates for genetic modification, however, endosymbiotic yeasts remain largely unexplored with little information on the symbiotic relationships to date. Here we review the recent report of symbiotic relationship between Wickerhamomyces anomalus (Pichia anomala) and several mosquito vector species as promising methods to implement control of mosquito-borne diseases. PMID:21113816

Ricci, Irene; Mosca, Michela; Valzano, Matteo; Damiani, Claudia; Scuppa, Patrizia; Rossi, Paolo; Crotti, Elena; Cappelli, Alessia; Ulissi, Ulisse; Capone, Aida; Esposito, Fulvio; Alma, Alberto; Mandrioli, Mauro; Sacchi, Luciano; Bandi, Claudio; Daffonchio, Daniele; Favia, Guido

2010-11-28

321

Biology and control of Taeniorhynchus (Mansonioides) uniformis Theobald, the chief vector of rural filariasis in Ceylon  

PubMed Central

Residual spraying of DDT for the control of Taeniorhynchus (Mansonioides) uniformis, the mosquito vector of rural filariasis in Ceylon, was carried out in Induruwa, a village on the west coast of the island. The results showed that the insecticide retained its effectiveness for a period of 4-6 months. During the course of this investigation, various observations were made on the behaviour of T. (M.) uniformis. Its host plants, day-time resting-places, feeding habits, and response to light—particularly moonlight—were recorded. An increase in T. (M.) uniformis prevalence was observed to coincide with the onset of the north-east and south-west monsoons, when the paddy-fields are inundated and become overgrown with Isachne australis, the most common aquatic plant in the area and a favourite breeding-place of this mosquito species.

Antonipulle, P.; David, H. V.; Karunaratne, M. D. R.

1958-01-01

322

Target product profile choices for intra-domiciliary malaria vector control pesticide products: repel or kill?  

PubMed Central

Background The most common pesticide products for controlling malaria-transmitting mosquitoes combine two distinct modes of action: 1) conventional insecticidal activity which kills mosquitoes exposed to the pesticide and 2) deterrence of mosquitoes away from protected humans. While deterrence enhances personal or household protection of long-lasting insecticidal nets and indoor residual sprays, it may also attenuate or even reverse communal protection if it diverts mosquitoes to non-users rather than killing them outright. Methods A process-explicit model of malaria transmission is described which captures the sequential interaction between deterrent and toxic actions of vector control pesticides and accounts for the distinctive impacts of toxic activities which kill mosquitoes before or after they have fed upon the occupant of a covered house or sleeping space. Results Increasing deterrency increases personal protection but consistently reduces communal protection because deterrent sub-lethal exposure inevitably reduces the proportion subsequently exposed to higher lethal doses. If the high coverage targets of the World Health Organization are achieved, purely toxic products with no deterrence are predicted to generally provide superior protection to non-users and even users, especially where vectors feed exclusively on humans and a substantial amount of transmission occurs outdoors. Remarkably, this is even the case if that product confers no personal protection and only kills mosquitoes after they have fed. Conclusions Products with purely mosquito-toxic profiles may, therefore, be preferable for programmes with universal coverage targets, rather than those with equivalent toxicity but which also have higher deterrence. However, if purely mosquito-toxic products confer little personal protection because they do not deter mosquitoes and only kill them after they have fed, then they will require aggressive "catch up" campaigns, with behaviour change communication strategies that emphasize the communal nature of protection, to achieve high coverage rapidly.

2011-01-01

323

Characterization of truck-mounted atomization equipment typically used in vector control.  

PubMed

The control of medically important arthropod vectors of human and animal disease is a high priority for both public health and military officials. Because droplet size of pesticide spray material is a critical factor affecting vector control applications, the droplet-size spectra produced by 11 sprayers and 3 spray formulations were evaluated. Droplet-size spectra were measured by a laser diffraction instrument, a hot-wire system, and rotating slides. There were considerable differences in the droplet-size spectra produced by the different sprayers tested. The volume median diameter (Dv0.5) for the water-based sprays ranged from 4.7 to 211 microm, depending on the sprayer, and the percent of spray volume contained in droplets less than 20 microm (%vol <20 microm) ranged between 0.5% and 98.9%. The Dv0.5 measurements for the oil-based sprays ranged from 9.4 to 125.3 microm and the %vol <20 microm ranged between 2.4% and 97.9%. The correlations between the Dv0.5 measured by the laser system (Dv0.5-laser) and the mass median diameter, Sauter diameter, and Dv0.5 measured by the AIMS probe were all significant. Generally, the slide Dv0.5s were numerically similar to the Dv0.5 from the laser system and the Sauter diameter from the Army Insecticide Measuring System probe. There was less consistent agreement between the % <32 microm values obtained from the slides and those from the other 2 samplers. The information presented can be used by applicators to select the sprayer that produces the droplet-size spectra needed for their particular application situation. PMID:17939514

Hoffmann, W C; Walker, T W; Martin, D E; Barber, J A B; Gwinn, T; Smith, V L; Szumlas, D; Lan, Y; Fritz, B K

2007-09-01

324

Control strategies for power smoothing using a flywheel driven by a sensorless vector-controlled induction machine operating in a wide speed range  

Microsoft Academic Search

This paper presents a novel control strategy for power smoothing. The system is based on a sensorless vector-controlled induction machine driving a flywheel. The problem of regulating the DC-link voltage against input power surges or sudden changes in load demand is addressed. The induction machine is controlled to operate in a wide speed range by using flux weakening above rated

Roberto Cárdenas; Rubén Peña; Greg M. Asher; Jon Clare; Ramón Blasco-Giménez

2004-01-01

325

High effective coverage of vector control interventions in children after achieving low malaria transmission in Zanzibar, Tanzania  

PubMed Central

Background Formerly a high malaria transmission area, Zanzibar is now targeting malaria elimination. A major challenge is to avoid resurgence of malaria, the success of which includes maintaining high effective coverage of vector control interventions such as bed nets and indoor residual spraying (IRS). In this study, caretakers' continued use of preventive measures for their children is evaluated, following a sharp reduction in malaria transmission. Methods A cross-sectional community-based survey was conducted in June 2009 in North A and Micheweni districts in Zanzibar. Households were randomly selected using two-stage cluster sampling. Interviews were conducted with 560 caretakers of under-five-year old children, who were asked about perceptions on the malaria situation, vector control, household assets, and intention for continued use of vector control as malaria burden further decreases. Results Effective coverage of vector control interventions for under-five children remains high, although most caretakers (65%; 363/560) did not perceive malaria as presently being a major health issue. Seventy percent (447/643) of the under-five children slept under a long-lasting insecticidal net (LLIN) and 94% (607/643) were living in houses targeted with IRS. In total, 98% (628/643) of the children were covered by at least one of the vector control interventions. Seasonal bed-net use for children was reported by 25% (125/508) of caretakers of children who used bed nets. A high proportion of caretakers (95%; 500/524) stated that they intended to continue using preventive measures for their under-five children as malaria burden further reduces. Malaria risk perceptions and different perceptions of vector control were not found to be significantly associated with LLIN effective coverage. Conclusions While the majority of caretakers felt that malaria had been reduced in Zanzibar, effective coverage of vector control interventions remained high. Caretakers appreciated the interventions and recognized the value of sustaining their use. Thus, sustaining high effective coverage of vector control interventions, which is crucial for reaching malaria elimination in Zanzibar, can be achieved by maintaining effective delivery of these interventions.

2013-01-01

326

Epidemiological impact of vector control. I. Incidence and changes in prevalence and intensity of Onchocerca volvulus infection.  

PubMed

Since 1974, the Onchocerciasis Control Programme (OCP) has been engaged in a large scale attempt to control the savanna species of the vector of onchocerciasis in seven West African countries. The effect of the vector control effort has been measured by epidemiological evaluation. For this purpose 474 villages have been examined by means of skin snip surveys between 1975 and 1983 and of these, 184 have been retained to-date for follow-up surveys which have documented over the years the reduction of the parasite population. The latest results of the epidemiological evaluation clearly demonstrate an outstanding success of the vector control campaign. The parasite has been or is close to being eliminated from the hyperendemic foci of the core area of the Programme. Major improvements have been registered in the reinvaded areas located at the Western and Eastern borders of the Programme. A major improvement has been found along the river Marahoué, the only focus of the intermediate area between the savanna and the forest where at the previous survey, the endemic situation was still similar to the pre-control situation. The exceptions to this gratifying picture are foci along the Dienkoa and Kulpawn rivers, both located in the core area, where transmission has relapsed and several more years of an effective vector control will be needed to eliminate the local parasite population. PMID:2378200

De Sole, G; Remme, J; Dadzie, K Y

1990-01-01

327

Diagnostic Accuracy of Molecular Amplification Tests for Human African Trypanosomiasis--Systematic Review  

PubMed Central

Background A range of molecular amplification techniques have been developed for the diagnosis of Human African Trypanosomiasis (HAT); however, careful evaluation of these tests must precede implementation to ensure their high clinical accuracy. Here, we investigated the diagnostic accuracy of molecular amplification tests for HAT, the quality of articles and reasons for variation in accuracy. Methodology Data from studies assessing diagnostic molecular amplification tests were extracted and pooled to calculate accuracy. Articles were included if they reported sensitivity and specificity or data whereby values could be calculated. Study quality was assessed using QUADAS and selected studies were analysed using the bivariate random effects model. Results 16 articles evaluating molecular amplification tests fulfilled the inclusion criteria: PCR (n?=?12), NASBA (n?=?2), LAMP (n?=?1) and a study comparing PCR and NASBA (n?=?1). Fourteen articles, including 19 different studies were included in the meta-analysis. Summary sensitivity for PCR on blood was 99.0% (95% CI 92.8 to 99.9) and the specificity was 97.7% (95% CI 93.0 to 99.3). Differences in study design and readout method did not significantly change estimates although use of satellite DNA as a target significantly lowers specificity. Sensitivity and specificity of PCR on CSF for staging varied from 87.6% to 100%, and 55.6% to 82.9% respectively. Conclusion Here, PCR seems to have sufficient accuracy to replace microscopy where facilities allow, although this conclusion is based on multiple reference standards and a patient population that was not always representative. Future studies should, therefore, include patients for which PCR may become the test of choice and consider well designed diagnostic accuracy studies to provide extra evidence on the value of PCR in practice. Another use of PCR for control of disease could be to screen samples collected from rural areas and test in reference laboratories, to spot epidemics quickly and direct resources appropriately.

Boer, Kimberly R.; Dyserinck, Heleen C.; Buscher, Philippe; Schallig, Henk D. H. F.; Leeflang, Mariska M. G.

2012-01-01

328

HLA-G 3' UTR-2 haplotype is associated with Human African trypanosomiasis susceptibility.  

PubMed

Trypanosoma brucei gambiense (Tbg) is responsible for the chronic form of Human African trypanosomiasis (HAT), classically lasting for years. Clinical evolution of HAT cases seems to be complex and reports on asymptomatic carriers and spontaneous cure have been published recently, strengthening the likely existence of the phenomenon of human trypanotolerance. Host's genetic factors could be involved in both the control of infection levels and the mortality rates, as clearly shown in experimental models, but also in human. Although genes directly involved in immune response are important candidates, genes implicated in the regulation of immunity, such as HLA-G, could also play a critical role. A candidate gene association study was previously conducted in the Democratic Republic of Congo using a family-based sample including 106 families (n=353). All individuals, from the Yansi ethnic group, were born in the area and had been exposed to the risk of infection since birth. We sequenced the HLA-G 3' untranslated region (UTR) and performed a family based association analysis of the 14 polymorphisms identified (14-bp insertion/deletion plus 13 SNPs). Three polymorphisms, 14-bp insertion/deletion and SNPs located at the +3003 and +3196 positions were associated to HAT (FBAT p=0.008, p=0.015 and p=0.022, respectively). HLA-G 3'UTR haplotypes were significantly associated with HAT (HBAT, global p=0.0026). UTR-2 haplotype (including 14-pb insertion and G allele at position +3196) was over-transmitted to the affected offspring (HBAT p=0.003) at the expense of UTR-4 haplotype, which was under-transmitted (HBAT p=0.013). These results are the first to report an association between polymorphisms in HLA-G and variable risks to develop HAT and suggest the involvement of the HLA-G molecule on HAT susceptibility. PMID:23541412

Courtin, David; Milet, Jacqueline; Sabbagh, Audrey; Massaro, Juliana D; Castelli, Erick C; Jamonneau, Vincent; Bucheton, Bruno; Sese, Claude; Favier, Benoit; Rouas-Freiss, Nathalie; Moreau, Philippe; Donadi, Eduardo A; Garcia, André

2013-03-26

329

Vector fuzzy control iterative algorithm for the design of sub-wavelength diffractive optical elements for beam shaping  

NASA Astrophysics Data System (ADS)

The vector fuzzy control iterative algorithm (VFCIA) is proposed for the design of phase-only sub-wavelength diffractive optical elements (SWDOEs) for beam shaping. The vector diffraction model put forward by Mansuripur is applied to relate the field distributions between the SWDOE plane and the output plane. Fuzzy control theory is used to decide the constraint method for each iterative process of the algorithm. We have designed a SWDOE that transforms a circular flat-top beam to a square irradiance pattern. Computer design results show that the SWDOE designed by the VFCIA can produce better results than the vector iterative algorithm (VIA). And the finite difference time-domain method (FDTD), a rigorous electromagnetic analysis technique, is used to analyze the designed SWDOE for further confirming the validity of the proposed method.

Lin, Yong; Hu, Jiasheng; Wu, Kenan

2009-08-01

330

The impact of development and malaria control activities on its vectors in the Kinabatangan area of Sabah, East Malaysia.  

PubMed

A study was carried out from July 2001 until January 2003 in the Kinabatangan area of Sabah, part of Borneo island, where malaria used to be mesoendemic. Vector surveys determined that Plasmodium falciparum was the predominant species and Anopheles balabacensis the primary vector. Malaria cases have dropped drastically over the years but P. falciparum is still predominant. In the present study, Anopheles donaldi was the predominant species and was positive for sporozoites. Although An. balabacensis was present, none were infective. An. donaldi bite more outdoors than indoors and have a peak biting time from 18:00 to 19:00 h when most people are still out of their homes. An integrated malaria control programme along with area development has helped in the control of malaria and its vector. PMID:16076459

Vythilingam, I; Chan, S T; Shanmugratnam, C; Tanrang, H; Chooi, K H

2005-10-01

331

Digitally controlled high-performance dc SQUID readout electronics for a 304-channel vector magnetometer  

NASA Astrophysics Data System (ADS)

Recently, we have developed a family of dc superconducting quantum interference device (SQUID) readout electronics for several applications. These electronics comprise a low-noise preamplifier followed by an integrator, and an analog SQUID bias circuit. A highly-compact low-power version with a flux-locked loop bandwidth of 0.3 MHz and a white noise level of 1 nV/?Hz was specially designed for a 304-channel low-Tc dc SQUID vector magnetometer, intended to operate in the new Berlin Magnetically Shielded Room (BMSR-2). In order to minimize the space needed to mount the electronics on top of the dewar and to minimize the power consumption, we have integrated four electronics channels on one 3 cm × 10 cm sized board. Furthermore we embedded the analog components of these four channels into a digitally controlled system including an in-system programmable microcontroller. Four of these integrated boards were combined to one module with a size of 4 cm × 4 cm × 16 cm. 19 of these modules were implemented, resulting in a total power consumption of about 61 W. To initialize the 304 channels and to service the system we have developed software tools running on a laptop computer. By means of these software tools the microcontrollers are fed with all required data such as the working points, the characteristic parameters of the sensors (noise, voltage swing), or the sensor position inside of the vector magnetometer system. In this paper, the developed electronics including the software tools are described, and first results are presented.

Bechstein, S.; Petsche, F.; Scheiner, M.; Drung, D.; Thiel, F.; Schnabel, A.; Schurig, Th

2006-06-01

332

Design and Implementation of Neuro-Fuzzy Vector Control for Wind-Driven Doubly-Fed Induction Generator  

Microsoft Academic Search

Wound-rotor induction generators have numerous advantages in wind power generation over other types of gener- ators. One scheme is realized when a converter cascade is used between the slip-ring terminals and the utility grid to control the rotor power. This configuration is called the doubly-fed induction generator (DFIG). In this paper, a vector control scheme is devel- oped to control

Hany M. Jabr; Dongyun Lu; Narayan C. Kar

2011-01-01

333

Self-adjusting and fuzzy logic gain schedulers for vector control of wind driven doubly-fed induction generator  

Microsoft Academic Search

Wind is one of the most efficient renewable energy sources available. Wound-rotor induction generators, specifically the doubly-fed induction generator, have numerous advantages in wind power generation in comparison to other generators. Doubly-fed induction generators use a converter cascade between the slip-ring terminals and the utility grid to control the rotor power. A vector control scheme developed to control the rotor

Hany M. Jabr; Lakshmi Varaha Iyer; Chitradeep Sen; Narayan C. Kar

2012-01-01

334

Status of Bovine Trypanosomiasis and Seasonal Variation in Its Occurrence in Zone 1 (Niger Valley) of the Republic of Mali.  

National Technical Information Service (NTIS)

Trypanosomiasis (sleeping sickness), inflicted by the prolific tsetse fly, is a major constraint to the development of the cattle industry in Mali. This report, responding to the paucity of scientific evidence on the extent of tsetse infestation, investig...

M. A. Q. Awan S. Maiga S. Bouare A. Telly

1981-01-01

335

Vector density and the control of kala-azar in Bihar, India.  

PubMed

Bihar, India has been in the grip of kala-azar for many years. Its rampant and severe spread has made life miserable in most parts of the state. Such conditions require a comprehensive understanding of this affliction. The numbers coming out of the districts prone to the disease in the north and south Ganges have provided us with several startling revelations, as there are striking uniformities on both sides, including similar vegetation, water storage facilities, house construction and little change in risk factors. The northern areas have been regularly sprayed with DDT since 1977, but eradication of the disease appears to be a distant dream. In 2007 alone, there were as many as 37,738 cases in that region. In contrast, the southern districts of Patna and Nalanda have never had the disease in its epidemic form and endemic disease has been present in only some pockets of the two districts. In those cases, two rounds of spraying with DDT had very positive results, with successful control and no new established foci. In addition, an eleven-year longitudinal study of the man hour density and house index for the vector Phlebotomus argentipes demonstrated that they were quite high in Patna and Nalanda and quite low in north Bihar. Given these facts, an attempt has been made to unravel the role of P. argentipes saliva (salivary gland) in the epidemiology of kala-azar. It was determined that patchy DDT spraying should be avoided for effective control of kala-azar. PMID:20027471

Kumar, V; Kesari, S; Kumar, A J; Dinesh, D S; Ranjan, A; Prasad, M; Sinha, N K; Kumar, R; Das, P

2009-11-01

336

Using the entomological inoculation rate to assess the impact of vector control on malaria parasite transmission and elimination  

PubMed Central

Background Prior studies have shown that annual entomological inoculation rates (EIRs) must be reduced to less than one to substantially reduce the prevalence of malaria infection. In this study, EIR values were used to quantify the impact of insecticide-treated bed nets (ITNs), indoor residual spraying (IRS), and source reduction (SR) on malaria transmission. The analysis of EIR was extended through determining whether available vector control tools can ultimately eradicate malaria. Method The analysis is based primarily on a review of all controlled studies that used ITN, IRS, and/or SR and reported their effects on the EIR. To compare EIRs between studies, the percent difference in EIR between the intervention and control groups was calculated. Results Eight vector control intervention studies that measured EIR were found: four ITN studies, one IRS study, one SR study, and two studies with separate ITN and IRS intervention groups. In both the Tanzania study and the Solomon Islands study, one community received ITNs and one received IRS. In the second year of the Tanzania study, EIR was 90% lower in the ITN community and 93% lower in the IRS community, relative to the community without intervention; the ITN and IRS effects were not significantly different. In contrast, in the Solomon Islands study, EIR was 94% lower in the ITN community and 56% lower in the IRS community. The one SR study, in Dar es Salaam, reported a lower EIR reduction (47%) than the ITN and IRS studies. All of these vector control interventions reduced EIR, but none reduced it to zero. Conclusion These studies indicate that current vector control methods alone cannot ultimately eradicate malaria because no intervention sustained an annual EIR less than one. While researchers develop new tools, integrated vector management may make the greatest impact on malaria transmission. There are many gaps in the entomological malaria literature and recommendations for future research are provided.

2010-01-01

337

Using an Artificial Neural Network as a Rotor Resistance Estimator in the Indirect Vector Control of an Induction Motor  

Microsoft Academic Search

This paper presents a rotor resistance estimator based on an artificial neural network (ANN) used in the indirect vector control (IVC) of an induction motor (IM). Attention is focused on the dynamic performance of ANN rotor estimator, which gives superior performance over the fuzzy logic based rotor estimator reported in technical literature. The simulation was done using a 1.5 HP

Huerta Gonzalez; Rodriguez Rivas; Torres Rodriguez

2008-01-01

338

Online Stator and Rotor Resistance Estimation Scheme Using Artificial Neural Networks for Vector Controlled Speed Sensorless Induction Motor Drive  

Microsoft Academic Search

This paper presents a new method of online estimation for the stator and rotor resistances of the induction motor for speed sensorless indirect vector controlled drives, using artificial neural networks. The error between the rotor flux linkages based on a neural network model and a voltage model is back propagated to adjust the weights of the neural network model for

Baburaj Karanayil; Muhammed Fazlur Rahman; Colin Grantham

2007-01-01

339

On-line stator and rotor resistance estimation scheme for vector-controlled induction motor drive using artificial neural networks  

Microsoft Academic Search

This paper presents a new method of on-line estimation for the stator and rotor resistances of the induction motor in the indirect vector controlled drive, using artificial neural networks. The back propagation algorithm is used for training of the neural networks. The error between the desired state variable of an induction motor and the actual state variable of a neural

Baburaj Karanayil; Muhammed Fazlur Rahman; Colin Grantham

2003-01-01

340

Implementation of an on-line resistance estimation using artificial neural networks for vector controlled induction motor drive  

Microsoft Academic Search

This paper presents a new method of on-line estimation for the stator and rotor resistances of the induction motor in the indirect vector controlled drive, using artificial neural networks. The backpropagation algorithm is used for training of the neural networks. The error between the desired state variable of an induction motor and the actual state variable of a neural model

B. Karanayil; M. F. Rahman; C. Grantham

2003-01-01

341

The evolution of ocular onchocerciasis in the Volta River Basin Area over a period of five years of vector control.  

PubMed

The results of an ophthalmological evaluation conducted in seven West African savannah villages before and after 5 years of vector control, were analysed to determine the effect of an interrupted or greatly reduced transmission of Onchocerca volvulus on the evolution of ocular onchocerciasis. Cross-sectional data showed a significant reduction of the prevalence of ocular onchocerciasis in five of the villages, and the rates of irreversible ocular lesions and blindness were generally lower after 5 years of vector control. A longitudinal study of a defined population showed that the ocular status of most patients with ocular onchocerciasis remained stable or improved over the 5 year period, particularly in lightly infected cases. The evolution of ocular onchocerciasis showed a deterioration in a minor proportion, restricted to cases of already existing severe lesions, resulting in blindness. A comparison of ophthalmic data from adjacent areas without vector control, indicates that a five year period of vector control may reduce the risk of developing eye lesions or blindness due to onchocerciasis by 50%. PMID:6608814

Dadzie, K Y; Rolland, A; Thylefors, B

1984-03-01

342

Geostatistical evaluation of integrated marsh management impact on mosquito vectors using before-after-control-impact (BACI) design  

Microsoft Academic Search

BACKGROUND: In many parts of the world, salt marshes play a key ecological role as the interface between the marine and the terrestrial environments. Salt marshes are also exceedingly important for public health as larval habitat for mosquitoes that are vectors of disease and significant biting pests. Although grid ditching and pesticides have been effective in salt marsh mosquito control,

Ilia Rochlin; Tom Iwanejko; Mary E Dempsey; Dominick V Ninivaggi

2009-01-01

343

Sensorless vector control of induction motors at very low speed using a nonlinear inverter model and parameter identification  

Microsoft Academic Search

The performance of vector-controlled induction motor drives without a speed sensor is generally poor at very low speed. The reasons are offset and drift components in the acquired feedback signals, voltage distortions caused by the nonlinear behavior of the switching converter, and the increased sensitivity against model parameter mismatch. New modeling and identification techniques are proposed to overcome these problems.

Joachim Holtz; Juntao Quan

2002-01-01

344

Refractory Air Vane and Refractory Material Research and Development. Task II - Refractory Materials for a Thrust Vector Control Valve.  

National Technical Information Service (NTIS)

This document reports the results of a 12-month contract to evaluate candidate refractory and insulator materials for use as the inlet duct liner, rotor, and nozzle exit, of a hot gas thrust vector control system. The purpose of this investigation was to ...

S. B. Moorhead

1974-01-01

345

The argument for integrating vector control with multiple drug administration campaigns to ensure elimination of lymphatic filariasis  

Microsoft Academic Search

BACKGROUND: There is a danger that mass drug administration campaigns may fail to maintain adequate treatment coverage to achieve lymphatic filariasis elimination. Hence, additional measures to suppress transmission might be needed to ensure the success of the Global Program for the Elimination of Lymphatic Filariasis. DISCUSSION: Vector control successfully eliminated lymphatic filariasis when implemented alone or with mass drug administration.

TR Burkot; DN Durrheim; WD Melrose; R Speare; K Ichimori

2006-01-01

346

A novel concept of a multiphase, multimotor vector controlled drive system supplied from a single voltage source inverter  

Microsoft Academic Search

Since variable speed electric drive systems are supplied from power electronic converters, it is possible to utilize ac machines with a phase number higher than three. It is shown in the paper, using general theory of electrical machines, that an increase of the stator phase number to at least five (or more) enables completely independent vector control of two (or

Emil Levi; Martin Jones; Slobodan N. Vukosavic; Hamid A. Toliyat

2004-01-01

347

A NOVEL CONCEPT OF A MULTIPHASE, MULTIMOTOR VECTOR CONTROLLED DRIVE SYSTEM SUPPLIED FROM A SINGLE VOLTAGE SOURCE INVERTER  

Microsoft Academic Search

Since variable speed electric drive systems are supplied from power electronic converters, it is possible to utilise AC machines with a phase number higher than three. It is shown in the paper, using general theory of electrical machines, that an increase of the stator phase number to at least five (or more) enables completely independent vector control of two (or

Emil Levi; Martin Jones; Slobodan N. Vukosavic; Hamid Toliyat

348

Model Reference Adaptive Controller-Based Rotor Resistance and Speed Estimation Techniques for Vector Controlled Induction Motor Drive Utilizing Reactive Power  

Microsoft Academic Search

In this paper, a detailed study on the model reference adaptive controller (MRAC) utilizing the reactive power is presented for the online estimation of rotor resistance to maintain proper flux orientation in an indirect vector controlled induction motor drive. Selection of reactive power as the functional candidate in the MRAC automatically makes the system immune to the variation of stator

Suman Maiti; Chandan Chakraborty; Yoichi Hori; Minh C. Ta

2008-01-01

349

The significance of controlled conditions in lentiviral vector titration and in the use of multiplicity of infection (MOI) for predicting gene transfer events  

PubMed Central

Background Although lentiviral vectors have been widely used for in vitro and in vivo gene therapy researches, there have been few studies systematically examining various conditions that may affect the determination of the number of viable vector particles in a vector preparation and the use of Multiplicity of Infection (MOI) as a parameter for the prediction of gene transfer events. Methods Lentiviral vectors encoding a marker gene were packaged and supernatants concentrated. The number of viable vector particles was determined by in vitro transduction and fluorescent microscopy and FACs analyses. Various factors that may affect the transduction process, such as vector inoculum volume, target cell number and type, vector decay, variable vector – target cell contact and adsorption periods were studied. MOI between 0–32 was assessed on commonly used cell lines as well as a new cell line. Results We demonstrated that the resulting values of lentiviral vector titre varied with changes of conditions in the transduction process, including inoculum volume of the vector, the type and number of target cells, vector stability and the length of period of the vector adsorption to target cells. Vector inoculum and the number of target cells determine the frequencies of gene transfer event, although not proportionally. Vector exposure time to target cells also influenced transduction results. Varying these parameters resulted in a greater than 50-fold differences in the vector titre from the same vector stock. Commonly used cell lines in vector titration were less sensitive to lentiviral vector-mediated gene transfer than a new cell line, FRL 19. Within 0–32 of MOI used transducing four different cell lines, the higher the MOI applied, the higher the efficiency of gene transfer obtained. Conclusion Several variables in the transduction process affected in in vitro vector titration and resulted in vastly different values from the same vector stock, thus complicating the use of MOI for predicting gene transfer events. Commonly used target cell lines underestimated vector titre. However, within a certain range of MOI, it is possible that, if strictly controlled conditions are observed in the vector titration process, including the use of a sensitive cell line, such as FRL 19 for vector titration, lentivector-mediated gene transfer events could be predicted.

Zhang, Bing; Metharom, Pat; Jullie, Howard; Ellem, Kay AO; Cleghorn, Geoff; West, Malcolm J; Wei, Ming Q

2004-01-01

350

A set of ontologies to drive tools for the control of vector-borne diseases  

Microsoft Academic Search

We are developing a set of ontologies dealing with vector-borne diseases as well as the arthropod vectors that transmit them. After building ontologies for mosquito and tick anatomy we continued this project with an ontology of insecticide resistance followed by a series of ontologies that describe malaria as well as physiological processes of mosquitoes that are relevant to, and involved

Pantelis Topalis; Emmanuel Dialynas; Elvira Mitraka; Elena Deligianni; Inga Siden-Kiamos; Christos Louis

2011-01-01

351

COMPUTATIONAL STUDY OF FLUIDIC THRUST VECTORING USING SEPARATION CONTROL IN A NOZZLE  

Microsoft Academic Search

A computational investigation of a two- dimensional nozzle was completed to assess the use of fluidic injection to manipulate flow separation and cause thrust vectoring of the primary jet thrust. The nozzle was designed with a recessed cavity to enhance the throat shifting method of fluidic thrust vectoring. The structured-grid, computational fluid dynamics code PAB3D was used to guide the

Karen A. Deere; Bobby L. Berrier; Jeffrey D. Flamm

2003-01-01

352

Strategies, effectiveness and rationale of vector-borne disease control in the pastoralist system of south-western Uganda.  

PubMed

In Uganda, control of vector-borne diseases is mainly in form of vector control, and chemotherapy. There have been reports that acaricides are being misused in the pastoralist systems in Uganda. This is because of the belief by scientists that intensive application of acaricide is uneconomical and unsustainable particularly in the indigenous cattle. The objective of this study was to investigate the strategies, rationale and effectiveness of vector-borne disease control by pastoralists. To systematically carry out these investigations, a combination of qualitative and quantitative research methods was used, in both the collection and the analysis of data. Cattle keepers were found to control tick-borne diseases (TBDs) mainly through spraying, in contrast with the control of trypanosomosis for which the main method of control was by chemotherapy. The majority of herders applied acaricides weekly and used an acaricide of lower strength than recommended by the manufacturers. They used very little acaricide wash, and spraying was preferred to dipping. Furthermore, pastoralists either treated sick animals themselves or did nothing at all, rather than using veterinary personnel. Oxytetracycline (OTC) was the drug commonly used in the treatment of TBDs. Nevertheless, although pastoralists may not have been following recommended practices in their control of ticks and tick-borne diseases, they were neither wasteful nor uneconomical and their methods appeared to be effective. Trypanosomosis was not a problem either in Sembabule or Mbarara district. Those who used trypanocides were found to use more drugs than were necessary. PMID:16248219

Mugisha, A; McLeod, A; Percy, R; Kyewalabye, E

2005-08-01

353

Mosquito vector control and biology in Latin America--a twelfth symposium. Denver, Colorado, February 2002. Summaries.  

PubMed

The 12th annual Latin American symposium presented by the American Mosquito Control Association (AMCA) was held as part of the 68th Annual Meeting in Denver, CO, in February 2002. The principal objective, as for the previous 11 symposia, was to promote participation in the AMCA by vector control specialists, public health workers, and academicians from Latin America. This publication includes summaries of 35 presentations that were given orally in Spanish or presented as posters by participants from 7 countries in Latin America. Topics addressed in the symposium included results from chemical and biological control programs and studies; studies of insecticide resistance; and population genetics, molecular, ecological, and behavioral studies of vectors of dengue (Aedes aegypti and Aedes albopictus) and other arboviruses, malaria (Anopheles albimanus and Anopheles pseudopunctipennis), leishmaniasis (Lutzomyia), and Chagas Disease (Triatoma). Related topics included biology and control of Culiseta inornata, Ochlerotatus taeniorhynchus, scorpions, Chironomus plumosus, and Musca domestica. PMID:12322934

Clark, Gary G; Martínez, Humberto Quiroz

2002-09-01

354

Ecologists can enable communities to implement malaria vector control in Africa  

PubMed Central

Background Integrated vector management (IVM) for malaria control requires ecological skills that are very scarce and rarely applied in Africa today. Partnerships between communities and academic ecologists can address this capacity deficit, modernize the evidence base for such approaches and enable future scale up. Methods Community-based IVM programmes were initiated in two contrasting settings. On Rusinga Island, Western Kenya, community outreach to a marginalized rural community was achieved by University of Nairobi through a community-based organization. In Dar es Salaam, Tanzania, Ilala Municipality established an IVM programme at grassroots level, which was subsequently upgraded and expanded into a pilot scale Urban Malaria Control Programme with support from national academic institutes. Results Both programmes now access relevant expertise, funding and policy makers while the academic partners benefit from direct experience of community-based implementation and operational research opportunities. The communities now access up-to-date malaria-related knowledge and skills for translation into local action. Similarly, the academic partners have acquired better understanding of community needs and how to address them. Conclusion Until sufficient evidence is provided, community-based IVM remains an operational research activity. Researchers can never directly support every community in Africa so community-based IVM strategies and tactics will need to be incorporated into undergraduate teaching programmes to generate sufficient numbers of practitioners for national scale programmes. Academic ecologists at African institutions are uniquely positioned to enable the application of practical environmental and entomological skills for malaria control by communities at grassroots level and should be supported to fulfil this neglected role.

Mukabana, W Richard; Kannady, Khadija; Kiama, G Michael; Ijumba, Jasper N; Mathenge, Evan M; Kiche, Ibrahim; Nkwengulila, Gamba; Mboera, Leonard; Mtasiwa, Deo; Yamagata, Yoichi; van Schayk, Ingeborg; Knols, Bart GJ; Lindsay, Steven W; de Castro, Marcia Caldas; Mshinda, Hassan; Tanner, Marcel; Fillinger, Ulrike; Killeen, Gerry F

2006-01-01

355

Evaluation of the effectiveness of malaria vector control measures in urban settings of Dakar by a specific anopheles salivary biomarker.  

PubMed

Standard entomological methods for evaluating the impact of vector control lack sensitivity in low-malaria-risk areas. The detection of human IgG specific to Anopheles gSG6-P1 salivary antigen reflects a direct measure of human-vector contact. This study aimed to assess the effectiveness of a range of vector control measures (VCMs) in urban settings by using this biomarker approach. The study was conducted from October to December 2008 on 2,774 residents of 45 districts of urban Dakar. IgG responses to gSG6-P1 and the use of malaria VCMs highly varied between districts. At the district level, specific IgG levels significantly increased with age and decreased with season and with VCM use. The use of insecticide-treated nets, by drastically reducing specific IgG levels, was by far the most efficient VCM regardless of age, season or exposure level to mosquito bites. The use of spray bombs was also associated with a significant reduction of specific IgG levels, whereas the use of mosquito coils or electric fans/air conditioning did not show a significant effect. Human IgG response to gSG6-P1 as biomarker of vector exposure represents a reliable alternative for accurately assessing the effectiveness of malaria VCM in low-malaria-risk areas. This biomarker tool could be especially relevant for malaria control monitoring and surveillance programmes in low-exposure/low-transmission settings. PMID:23840448

Drame, Papa Makhtar; Diallo, Abdoulaye; Poinsignon, Anne; Boussari, Olayide; Dos Santos, Stephanie; Machault, Vanessa; Lalou, Richard; Cornelie, Sylvie; LeHesran, Jean-Yves; Remoue, Franck

2013-06-20

356

Evaluation of the Effectiveness of Malaria Vector Control Measures in Urban Settings of Dakar by a Specific Anopheles Salivary Biomarker  

PubMed Central

Standard entomological methods for evaluating the impact of vector control lack sensitivity in low-malaria-risk areas. The detection of human IgG specific to Anopheles gSG6-P1 salivary antigen reflects a direct measure of human–vector contact. This study aimed to assess the effectiveness of a range of vector control measures (VCMs) in urban settings by using this biomarker approach. The study was conducted from October to December 2008 on 2,774 residents of 45 districts of urban Dakar. IgG responses to gSG6-P1 and the use of malaria VCMs highly varied between districts. At the district level, specific IgG levels significantly increased with age and decreased with season and with VCM use. The use of insecticide-treated nets, by drastically reducing specific IgG levels, was by far the most efficient VCM regardless of age, season or exposure level to mosquito bites. The use of spray bombs was also associated with a significant reduction of specific IgG levels, whereas the use of mosquito coils or electric fans/air conditioning did not show a significant effect. Human IgG response to gSG6-P1 as biomarker of vector exposure represents a reliable alternative for accurately assessing the effectiveness of malaria VCM in low-malaria-risk areas. This biomarker tool could be especially relevant for malaria control monitoring and surveillance programmes in low-exposure/low-transmission settings.

Drame, Papa Makhtar; Diallo, Abdoulaye; Poinsignon, Anne; Boussari, Olayide; Dos Santos, Stephanie; Machault, Vanessa; Lalou, Richard; Cornelie, Sylvie; LeHesran, Jean-Yves; Remoue, Franck

2013-01-01

357

Analysis and Development of a Resolution-Level Vector-Controlled WM Inverter-Fed IPM Motor Drive  

Microsoft Academic Search

This paper presents the development, the analysis and the implementation of a resolution-level vector- controlled wavelet-modulated (WM) inverter-fed interior permanent magnet (IPM) motor drive. The proposed controller is based on mapping the changes of the quadrature axis component iq of the line currents to a phase-shift angle thetas, while maintaining the direct axis component id constant. The phase-shift thetas is

S. A. Saleh; M. A. Rahman

2008-01-01

358

Statistical discrimination of steroid profiles in doping control with support vector machines.  

PubMed

Due to their performance enhancing properties, use of anabolic steroids (e.g. testosterone, nandrolone, etc.) is banned in elite sports. Therefore, doping control laboratories accredited by the World Anti-Doping Agency (WADA) screen among others for these prohibited substances in urine. It is particularly challenging to detect misuse with naturally occurring anabolic steroids such as testosterone (T), which is a popular ergogenic agent in sports and society. To screen for misuse with these compounds, drug testing laboratories monitor the urinary concentrations of endogenous steroid metabolites and their ratios, which constitute the steroid profile and compare them with reference ranges to detect unnaturally high values. However, the interpretation of the steroid profile is difficult due to large inter-individual variances, various confounding factors and different endogenous steroids marketed that influence the steroid profile in various ways. A support vector machine (SVM) algorithm was developed to statistically evaluate urinary steroid profiles composed of an extended range of steroid profile metabolites. This model makes the interpretation of the analytical data in the quest for deviating steroid profiles feasible and shows its versatility towards different kinds of misused endogenous steroids. The SVM model outperforms the current biomarkers with respect to detection sensitivity and accuracy, particularly when it is coupled to individual data as stored in the Athlete Biological Passport. PMID:23473248

Van Renterghem, Pieter; Sottas, Pierre-Edouard; Saugy, Martial; Van Eenoo, Peter

2013-01-14

359

Indigenous knowledge system for treatment of trypanosomiasis in Kaduna state of Nigeria.  

PubMed

A survey was carried out in Kaduna State of Nigeria to establish the indigenous knowledge system for treating trypanosomiasis in domestic animals. Questionnaire and interviews were, respectively, administered to, or conducted with about 200 livestock farmers and traders spread around the state. Data obtained revealed the use of several plants either alone or in combination, for the treatment and management of trypasonomiasis. The most common plants encountered were Adansonia digitata, Terminalia avicennoides, Khaya senegalensis, Cissus populnea, Tamarindus indica, Lawsonia inermis, Boswellia dalzielli, Pseudocedrela kotschi, Syzyium quinensis, Sterculia setigera, Afzelia africana, Prosopis africana, Lancea kerstingii. The method of preparation and mode of administration of some of these plants in the treatment of trypanosomiasis are reviewed and discussed. PMID:11801393

Atawodi, S E; Ameh, D A; Ibrahim, S; Andrew, J N; Nzelibe, H C; Onyike, E O; Anigo, K M; Abu, E A; James, D B; Njoku, G C; Sallau, A B

2002-02-01

360

Delayed recovery of adrenocortical and testicular function after chemotherapy of human trypanosomiasis.  

PubMed

The following indicators of pituitary, adreno-cortical and testicular function were measured in 58 male African trypanosomiasis patients from Western Kenya; plasma cortisol, luteinizing hormone (LH) and testosterone levels. The measurements were carried out by specific radioimmunoassay methods in early and late stage infected patients on admission to hospital and in both groups of patients after one month of chemotherapy. Packed cell volume (PCV) and hemoglobin levels were also measured in all the patients to determine the extent of their anaemia and success of recovery. High parasitaemia, anaemia and clinical symptoms of human trypanosomiasis were found in the infected patients and were eliminated with chemotherapy in the infected/treated patients. Increased levels of cortisol and decreased concentrations of testosterone without significant changes in LH levels were evident in the infected patients; this condition remained unchanged even after one month of chemotherapy. Evidence is thus provided of persistent hormonal perturbations which probably indicate residual endocrine organ damage. PMID:7942356

Kimata, D M; Makawiti, D W; Tengekyon, K M; Dadzie, S; Waindi, E N

1994-06-01

361

Human trypanosomiasis caused by Trypanosoma evansi in India: the first case report.  

PubMed

We report an Indian farmer who had fluctuating trypanosome parasitemia associated with febrile episodes for five months. Morphologic examination of the parasites indicated the presence of large numbers of trypanosomes belonging to the species Trypanosoma evansi, which is normally a causative agent of animal trypanosomiasis known as surra. Basic clinical and biologic examinations are described, using several assays, including parasitologic, serologic, and molecular biologic tests, all of which confirmed the infecting species as T. evansi. Analysis of cerebrospinal fluid indicated no invasion of the central nervous system (CNS) by trypanosomes. Suramin, a drug used exclusively for treatment of early-stage human African trypanosomiasis with no CNS involvement, effected apparent cure in the patient. This is the first case reported of human infection due to Trypanosoma evansi, which was probably caused by transmission of blood from an infected animal. PMID:16172469

Joshi, Prashant P; Shegokar, Vijay R; Powar, Rajaram M; Herder, Stephane; Katti, Rahul; Salkar, Harsha R; Dani, Vibhawari S; Bhargava, Aradhana; Jannin, Jean; Truc, Philippe

2005-09-01

362

Inductance and Active Phase Vector Based Torque Control for Switched Reluctance Motor Drives.  

NASA Astrophysics Data System (ADS)

The Switched Reluctance Motor (SRM) drive technology has developed significantly over the last few years. The simplicity in both motor design and power converter requirement along with the availability of high frequency, high power semiconductor switches have made SRMs compete with conventional adjustable speed drive technologies. The subject of winding current control in switched reluctance machines has always been associated with the shaft position information. The use of inductance for direct commutation control is the central subject of this dissertation. In contrast to the conventional methods based on position commutation, new methods of control based on inductance commutation are presented. The object of a commutation algorithm is to switch the currents in the phase coils, in order to provide continuous energy conversion with maximum torque output for a given unit of input current. Since torque production in a SRM is based on the concept of variable reluctance, it makes more sense to observe the instantaneous phase inductance or reluctance instead of estimating the rotor position. The inductance sensors observe the machine parameters and provide sufficient information on the electrical characteristics of the coils. This control strategy avoids the inductance to position transformation blocks conventionally used in SRM control systems. In a typical SRM, the phase coils have a nonlinear behavior of inductance due to effects of current saturation. Also the parameters of one phase coil differ from those of the other due to manufacturing tolerances or due to bearing wear. In such cases, the algorithms written during the stage of manufacturing may not be valid after parameter changes. Optimizing torque production in the event of phase asymmetry and saturation is developed in this research. Indirect sensors connected to the active phase coil of the SRM are based on sensing the flux level in the active coil. New commutation algorithms based on flux sensing concepts are derived and commutation based on observable phase coil parameters are developed. The commutation methods are based on a composite vector of the observable parameters of the active phase coil. These methods work on a tabular approach which is ideal for implementation using digital computers.

Kalpathi, Ramani Raman

363

Diagnostic Accuracy of Molecular Amplification Tests for Human African Trypanosomiasis—Systematic Review  

Microsoft Academic Search

BackgroundA range of molecular amplification techniques have been developed for the diagnosis of Human African Trypanosomiasis (HAT); however, careful evaluation of these tests must precede implementation to ensure their high clinical accuracy. Here, we investigated the diagnostic accuracy of molecular amplification tests for HAT, the quality of articles and reasons for variation in accuracy.MethodologyData from studies assessing diagnostic molecular amplification

Claire M. Mugasa; Emily R. Adams; Kimberly R. Boer; Heleen C. Dyserinck; Philippe Büscher; Henk D. H. F. Schallig; Mariska M. G. Leeflang

2012-01-01

364

Treatment of human African trypanosomiasis--present situation and needs for research and development.  

PubMed

Human African trypanosomiasis re-emerged in the 1980s. However, little progress has been made in the treatment of this disease over the past decades. The first-line treatment for second-stage cases is melarsoprol, a toxic drug in use since 1949. High therapeutic failure rates have been reported recently in several foci. The alternative, eflornithine, is better tolerated but difficult to administer. A third drug, nifurtimox, is a cheap, orally administered drug not yet fully validated for use in human African trypanosomiasis. No new drugs for second-stage cases are expected in the near future. Because of resistance to and limited number of current treatments, there may soon be no effective drugs available to treat trypanosomiasis patients, especially second-stage cases. Additional research and development efforts must be made for the development of new compounds, including: testing combinations of current trypanocidal drugs, completing the clinical development of nifurtimox and registering it for trypanosomiasis, completing the clinical development of an oral form of eflornithine, pursuing the development of DB 289 and its derivatives, and advancing the pre-clinical development of megazol, eventually engaging firmly in its clinical development. Partners from the public and private sector are already engaged in joint initiatives to maintain the production of current drugs. This network should go further and be responsible for assigning selected teams to urgently needed research projects with funds provided by industry and governments. At the same time, on a long term basis, ambitious research programmes for new compounds must be supported to ensure the sustainable development of new drugs. PMID:12127356

Legros, Dominique; Ollivier, Gaëlle; Gastellu-Etchegorry, Marc; Paquet, Christophe; Burri, Christian; Jannin, Jean; Büscher, Philippe

2002-07-01

365

The Atlas of human African trypanosomiasis: a contribution to global mapping of neglected tropical diseases  

Microsoft Academic Search

BACKGROUND: Following World Health Assembly resolutions 50.36 in 1997 and 56.7 in 2003, the World Health Organization (WHO) committed itself to supporting human African trypanosomiasis (HAT)-endemic countries in their efforts to remove the disease as a public health problem. Mapping the distribution of HAT in time and space has a pivotal role to play if this objective is to be

Pere P Simarro; Giuliano Cecchi; Massimo Paone; José R Franco; Abdoulaye Diarra; José A Ruiz; Eric M Fèvre; Fabrice Courtin; Raffaele C Mattioli; Jean G Jannin

2010-01-01

366

Ecology and Control of Dengue Vectors on an Island in the Gulf of Thailand.  

National Technical Information Service (NTIS)

Entomological observations made on Koh Samui during an epidemic of dengue hemorrhagic fever in 1967 indicated that the densities of the populations of the 2 vector species, Aedes aegypti and Aedes albopictus, were directly related to the amount of rainfal...

D. J. Gould G. A. Mount H. R. Ford J. E. Scanlon M. F. Sullivan

1970-01-01

367

A versatile vector for controlled expression of genes in Escherichia coli and Salmonella typhimurium  

Microsoft Academic Search

We have constructed two expression vectors based on the pJF118HE vector developed for Escherichia coli by Fürste et al. [Gene 48 (1986) 119–131]. The tac promoter (ptac) was exchanged for the trc promoter (ptrc) and an NdeI site was created at the appropriate distance from the ribosome-binding site. The NdeI site permits cloning of a gene at its translation start

Joyce S. Velterop; Marjoleine A. Dijkhuizen; Rechien van't Hof; Pieter W. Postma

1995-01-01

368

Program-controlled soft switching PRDCL inverter with new space vector PWM algorithm  

Microsoft Academic Search

A soft-switched space vector pulse-width-modulated (PWM) inverter is developed using a novel parallel resonant DC link (PRDCL). This PRDCL can operate on variable DC link pulse position and width, resulting in enhanced PWM capability, which is superior to that of other resonant DC links. A space vector algorithm suitable for this PRDCL inverter is presented. The algorithm eliminates narrow PWM

Wan Yi; Hyo L Liu; Yong C. Jung; Jung G. Cho; Gyu H. Cho

1992-01-01

369

Program-controlled soft switching PRDCL inverter with new space vector PWM algorithm  

Microsoft Academic Search

A soft switched space vector PWM inverter is developed using new parallel resonant DC-link (PRDCL). This PRDCL can operate on variable DC-link pulse position and width resulting in enhanced PWM capability, which is superior to other resonant DC-links. A new space vector algorithm is presented suitable for this PRDCL inverter. The suggested algorithm is able to eliminate narrow PWM pulses

WAN YI; HYO L. LlU; YONG C. JUNG; JUNG G. CHO; GYU H. CHO

1993-01-01

370

Vector control and foliar nutrition to maintain economic sustainability of bearing citrus in Florida groves affected by huanglongbing.  

PubMed

BACKGROUND: Huanglongbing (HLB) or citrus greening is a bacterial disease vectored by the Asian citrus psyllid (ACP) causing tree decline, and yield loss. Vector control and foliar nutrition are used in Florida to slow the spread of HLB and mitigate debilitating effects of the disease. A four year replicated field study was initiated February 2008 in a 5.2-ha commercial block of young 'Valencia' orange trees employing a factorial design to evaluate individual and compound effects of vector management and foliar nutrition. Insecticides were sprayed during tree dormancy and when psyllid populations exceeded a nominal threshold. A mixture consisting primarily of micro- and macro-nutrients was applied three times a year corresponding to the principal foliar flushes. RESULTS: Differences in ACP numbers from five- to 13-fold were maintained in insecticide treated and untreated plots. Incidence of HLB estimated by polymerase chain reaction (PCR), rose from 30% at the beginning of the study to 95% in only 18 months. Highest yields all four years were seen from trees receiving both foliar nutrition and vector control. Production for these trees in the fourth year was close to the pre-HLB regional average for 10 year old 'Valencia' on 'Swingle'. Nevertheless, at current juice prices, the extra revenue generated from the combined insecticide and nutritional treatment did not cover the added treatment costs. CONCLUSIONS: This experiment demonstrated that vector control, especially when combined with enhanced foliar nutrition, could significantly increase yields in a citrus orchard with high incidence of HLB. Economic thresholds for both insecticide and nutrient applications are needed under different market and environmental conditions. PMID:23666807

Stansly, Philip A; Arevalo, H Alejandro; Qureshi, Jawwad A; Jones, Moneen M; Hendricks, Katherine; Roberts, Pamela D; Roka, Fritz M

2013-05-11

371

Surveillance and Vector Control of Lymphatic Filariasis in the Republic of Korea  

PubMed Central

Objectives Until the early 2000s, lymphatic filariasis would commonly break out in the coastal areas in Korea. Through steady efforts combining investigation and treatment, filariasis was officially declared eradicated in 2008. This study surveyed the density of vector species of filariasis in past endemic areas, and inspected filariasis DNA from collected mosquitoes for protection against the reemergence of filariasis. Methods Between May and October 2009, mosquitoes were caught using the black night trap in past endemic coastal areas: Gyeongsangnam-do, Jeollanamdo, and Jeju-do. The collected mosquitoes were identified, and the extracted DNA from the collected vector mosquitoes was tested by polymerase chain reaction for Brugia malayi filariasis. Results Ochletotatus togoi, Anophel es (Hyrcanus) group and Culex pipiens were most frequently caught in Jeollanam-do (Geomun Island, Bogil Island, Heuksan Island), Jeju-do (Namone-ri, Wimi-ri). and Gyeongsangnam-do (Maemul Island). DNA of B malayi was not found in Och Togoi and An (Hyrcanus) group as main vectors of filariasis. Conclusion Lymphatic filariasis was not found in the vector mosquitoes collected in past endemic areas. However, considering that the proportion of vector species is quite high, there is a potential risk that filariasis could be reemerging through overseas travel or trade. Thus, there is a need to continuously monitor vector mosquitoes of lymphatic filariasis.

Cho, Shin Hyeong; Ma, Da Won; Koo, Bo Ra; Shin, Hee Eun; Lee, Wook Kyo; Jeong, Byong Suk; Chu, Chaeshin; Lee, Won Ja; Cheun, Hyeng Il

2012-01-01

372

Application of eco-friendly tools and eco-bio-social strategies to control dengue vectors in urban and peri-urban settings in Thailand  

PubMed Central

Background: Dengue is considered one of the most important vector-borne diseases in Thailand. Its incidence is increasing despite routine implementation of national dengue control programmes. This study, conducted during 2010, aimed to demonstrate an application of integrated, community-based, eco-bio-social strategies in combination with locally-produced eco-friendly vector control tools in the dengue control programme, emphasizing urban and peri-urban settings in eastern Thailand. Methodology: Three different community settings were selected and were randomly assigned to intervention and control clusters. Key community leaders and relevant governmental authorities were approached to participate in this intervention programme. Ecohealth volunteers were identified and trained in each study community. They were selected among active community health volunteers and were trained by public health experts to conduct vector control activities in their own communities using environmental management in combination with eco-friendly vector control tools. These trained ecohealth volunteers carried out outreach health education and vector control during household visits. Management of public spaces and public properties, especially solid waste management, was efficiently carried out by local municipalities. Significant reduction in the pupae per person index in the intervention clusters when compared to the control ones was used as a proxy to determine the impact of this programme. Results: Our community-based dengue vector control programme demonstrated a significant reduction in the pupae per person index during entomological surveys which were conducted at two-month intervals from May 2010 for the total of six months in the intervention and control clusters. The programme also raised awareness in applying eco-friendly vector control approaches and increased intersectoral and household participation in dengue control activities. Conclusion: An eco-friendly dengue vector control programme was successfully implemented in urban and peri-urban settings in Thailand, through intersectoral collaboration and practical action at household level, with a significant reduction in vector densities.

Kittayapong, Pattamaporn; Thongyuan, Suporn; Olanratmanee, Phanthip; Aumchareoun, Worawit; Koyadun, Surachart; Kittayapong, Rungrith; Butraporn, Piyarat

2012-01-01

373

Lethal and Pre-Lethal Effects of a Fungal Biopesticide Contribute to Substantial and Rapid Control of Malaria Vectors  

PubMed Central

Rapidly emerging insecticide resistance is creating an urgent need for new active ingredients to control the adult mosquitoes that vector malaria. Biopesticides based on the spores of entomopathogenic fungi have shown considerable promise by causing very substantial mortality within 7–14 days of exposure. This mortality will generate excellent malaria control if there is a high likelihood that mosquitoes contact fungi early in their adult lives. However, where contact rates are lower, as might result from poor pesticide coverage, some mosquitoes will contact fungi one or more feeding cycles after they acquire malaria, and so risk transmitting malaria before the fungus kills them. Critics have argued that ‘slow acting’ fungal biopesticides are, therefore, incapable of delivering malaria control in real-world contexts. Here, utilizing standard WHO laboratory protocols, we demonstrate effective action of a biopesticide much faster than previously reported. Specifically, we show that transient exposure to clay tiles sprayed with a candidate biopesticide comprising spores of a natural isolate of Beauveria bassiana, could reduce malaria transmission potential to zero within a feeding cycle. The effect resulted from a combination of high mortality and rapid fungal-induced reduction in feeding and flight capacity. Additionally, multiple insecticide-resistant lines from three key African malaria vector species were completely susceptible to fungus. Thus, fungal biopesticides can block transmission on a par with chemical insecticides, and can achieve this where chemical insecticides have little impact. These results support broadening the current vector control paradigm beyond fast-acting chemical toxins.

Blanford, Simon; Shi, Wangpeng; Christian, Riann; Marden, James H.; Koekemoer, Lizette L.; Brooke, Basil D.; Coetzee, Maureen; Read, Andrew F.; Thomas, Matthew B.

2011-01-01

374

Sensor-less speed control strategy for induction motor drive incorporating vector controlled scheme PWM inverter-fed with auto-tuning machine parameter estimation  

Microsoft Academic Search

This paper presents a feasible development on a highly accurate quick response adjustable speed drive implementation for general purpose induction motor which operates on the basis of sensorless slip frequency type vector controlled sine-wave PWM inverter with automatic tuning machine parameter estimation schemes. The dynamic speed response performances for largely changed load torque disturbances as well as steady state speed

Koji Soshin; Tarek Ahmed; Mutsuo Nakaoka; Yukihiko Okamura

2003-01-01

375

3D vector control during alveolar ridge augmentation using distraction osteogenesis and temporary anchorage devices: a new technique.  

PubMed

This report describes a combined orthodontic surgical technique involving vertical alveolar distraction using temporary anchorage devices (TADs) in cases of massive alveolar ridge bone and teeth loss. A combined surgical orthodontic protocol included presurgical orthodontic preparation and a preimplantation surgical augmentation stage for insertion of a vertical distractor. During the active vertical alveolar distraction process TADs were inserted. Intraoral orthodontic elastics were attached to the main orthodontic archwire exerting multidirectional forces to control the vertical distraction vector. After 3 months of vector controlling and active bone moulding, the TADs were removed. Anterior alveolar ridge augmentation using distraction osteogenesis was achieved. The application of TADs for better anterior segment curvature enabled dental implant insertion, better positioning and restoration. A combined surgical orthodontic management protocol involving vertical alveolar distraction osteogenesis for augmentation purposes is an efficient treatment method to improve alveolar ridge volume for the preimplantation stage. PMID:21978932

Aizenbud, D; Hazan-Molina, H; Cohen, M; Rachmiel, A

2011-10-05

376

Amelioration of Retroviral Vector Silencing in Locus Control Region ?-Globin-Transgenic Mice and Transduced F9 Embryonic Cells  

PubMed Central

Retroviral vectors are transcriptionally silenced in hematopoietic stem cells, and this phenomenon must be overcome for effective gene therapy of blood diseases. The murine stem cell virus (MSCV) vector completely silences ?-globin reporter genes regulated by locus control region (LCR) elements 5?HS2 to 5?HS4 in seven of eight transgenic mice. Here, we show that no single known MSCV silencer element is sufficient for complete LCR ?-globin transgene silencing. However, partial silencing of high-copy transgenes is conveyed by the MSCV direct repeat and promoter elements. The CpG methylation pattern of silenced and expressed MSCV promoter transgenes is virtually identical, demonstrating that silencing does not absolutely correlate with methylation status. Combined mutations in all four MSCV silencer elements leads to expression of ?-globin in 6 of 10 transgenic mice. The same mutations incorporated into the HSC1 retrovirus vector direct neo gene expression in 71% of transduced F9 embryonic carcinoma cells. These studies demonstrate that combined mutation of four retroviral silencer elements relieves complete silencing in most transgenic mice and transduced F9 cells and suggests that novel silencer elements remain. Enhanced expression of the HSC1 vector in primitive stem cells is well suited for blood gene therapy applications.

Osborne, Cameron S.; Pasceri, Peter; Singal, Rakesh; Sukonnik, Tanya; Ginder, Gordon D.; Ellis, James

1999-01-01

377

466. Long-Term Rapamycin Control of Transgene Expression in Mouse Salivary Glands in a Single AAV Vector  

Microsoft Academic Search

Background: Salivary glands are a promising gene transfer platform for secretory therapeutic protein delivery (Baum et al., Trends Mol Med 2004; Zufferey and Aebischer, Gene Ther 2004). For ideal clinical application, therapeutic protein levels need to be controlled. We have shown, as proof-of-concept, that the rapamycin-inducible dimerizer system can regulate transgene expression from salivary glands after delivery with adenoviral vectors

Jianghua Wang; Antonis Voutetakis; Milton Papa; Victor M. Rivera; Tim Clackson; Beatrijs M. Lodde; Fumi Mineshiba; Bruce J. Baum

2005-01-01

378

Fully digital, vector-controlled PWM VSI-fed AC drives with an inverter dead-time compensation strategy  

Microsoft Academic Search

A dead-time compensation method in vector-controlled pulse width modulator (PWM) voltage source inverters (VSIs) is proposed. The method is based on a feedforward approach that produces compensating signals obtained from the Id-Iq current and inverter output angular frequency references in the rotating reference (d-q) frame. It provides excellent inverter output voltage distortion correction for both fundamental and harmonic components. The

Takashi Sukegawa; Keno Kamiyama; Katsuhiro Mizuno; Takayuki Matsui; Toshiaki Okuyama

1991-01-01

379

Bacteriophage lambda- E. coli K12 vector-host system for gene cloning and expression under lactose promoter control  

Microsoft Academic Search

Bacteriophage lambda vectors, derived from ?plac5 were constructed. Their genomes have only one EcoRI restriction site, located near the end of the ß-galactosidase gene. Recombinants, constructed in vitro, having a DNA fragment inserted in the EcoRI site, are lac- and can be easily recognized. Expression of such foreign genes is then under the control of the lac promoter. Mutations Qam73

Christine Pourcel; Christian Marchal; Anne Louise; Alexandre Fritsch; Pierre Tiollais

1979-01-01

380

Significant changes in systolic blood pressure post vectored upper cervical adjustment vs resting control groups: A possible effect of the cervicosympathetic and\\/or pressor reflex  

Microsoft Academic Search

Objective: To determine whether a vectored adjustment of the atlas in patients identified as demonstrating signs of upper cervical joint dysfunction would cause lowering of blood pressure in comparison with resting controls. Design: Test 1: controlled clinical trial with a treatment (adjustment) group and a control (resting) group. Test 2: controlled clinical trial with subjects serving as their own controls.

Gary A. Knutson

2001-01-01

381

Genetics of the Encephalitis Vector, 'Culex tarsalis' for Possible Application in Integrated Control.  

National Technical Information Service (NTIS)

The projects here reported part of an overall program designed to change Culex tarsalis genetically to inhibit its propagation in nature, and to render it less effective as a vector of disease. A resume of progress for the year 1978-79 is as follows: The ...

M. Asman

1979-01-01

382

Potential Games: A Framework for Vector Power Control Problems With Coupled Constraints  

Microsoft Academic Search

In this paper we propose a unified framework, based on the emergent potential games to deal with a variety of network resource allocation problems. We generalize the existing results on potential games to the cases where there exists coupling among the (possibly vector) strategies of all players. We derive sufficient conditions for the existence and uniqueness of the Nash equilibrium,

G. Scutari; S. Barbarossa; D. P. Palomar

2006-01-01

383

Dengue vector control and surveillance during a major outbreak in a coastal Red Sea area in Sudan.  

PubMed

An unprecedented dengue outbreak occurred in 2010 in Port Sudan city, Sudan. Dengue incidence was 94 cases per 10 000 observed over 17 epidemiological weeks (total cases = 3 765). We report here the impact of the vector control response plan to the outbreak, which mainly entailed house inspection and insecticide space spraying. In total 3 048 houses were inspected during vector surveillance and 19 794 larvae and 3 240 pupae of Aedes aegypti were collected. Entomological indices decreased during the period: house index declined from 100% to 16% (F= 57.8, P < 0.001) and pupal/person (P/P) index from 0.77 to 0.10 (F= 3.06, P < 0.01) in weeks 9 and 21 respectively. This decline was accompanied by a decrease in cases from a peak of 341 cases in week 13 to zero in week 29 and the end of the outbreak. There was a significant correlation between the entomological parameters and dengue incidence (R2 = 0.83, F= 23.9, P < 0.001). Integrated epidemiological and vector surveillance is essential to an effective dengue control programme PMID:23301396

Seidahmed, O M E; Siam, H A M; Soghaier, M A; Abubakr, M; Osman, H A; Abd Elrhman, L S; Elmagbol, B; Velayudhan, R

2012-12-01

384

Boundaries of the Origin of Replication: Creation of a pET-28a-Derived Vector with p15A Copy Control Allowing Compatible Coexistence with pET Vectors  

PubMed Central

During our studies involving protein-DNA interactions, we constructed plasmid pSAM to fulfill two requirements: 1) to facilitate transfer of cloned sequences from widely used expression vector pET-28a(+), and 2) to provide a vector compatible with pBR322-derived plasmids for use in cells harboring two different plasmids. Vector pSAM is a pET-28a(+)-derived plasmid with the p15A origin of replication (ori); pET-28a(+) contains the pBR322 replicon that is incompatible with other pBR322-derived plasmids. By replacing the original pET-28a(+) replicon–comprising the ori, RNAI, RNAII, and Rom–with the p15A replicon, we generated pSAM, which contains the pET-28a(+) multiple cloning site and is now compatible with pBR322-derived vectors. Plasmid copy number was assessed using quantitative PCR: pSAM copy number was maintained at 18±4 copies per cell, consistent with that of other p15A-type vectors. Compatibility with pBR322-derived vectors was tested with pGEX-6p-1 and pSAM, which maintained their copy numbers of 49±10 and 14±4, respectively, when both were present within the same cell. Swapping of the ori is a common practice; however, it is vital that all regions of the original replicon be removed. Additional vector pSAMRNAI illustrated that incompatibility remains when portions of the replicon, such as RNAI and/or Rom, are retained; pSAMRNAI, which contains the intact RNAI but not ROM, lowered the copy number of pGEX-6p-1 to 18±2 in doubly transformed cells due to retention of the pET-28a(+)-derived RNAI. Thus, pSAMRNAI is incompatible with vectors controlled by the pBR322 replicon and further demonstrates the need to remove all portions of the original replicon and to quantitatively assess copy number, both individually and in combination, to ensure vector compatibility. To our knowledge, this is the first instance where the nascent vector has been quantitatively assessed for both plasmid copy number and compatibility. New vector pSAM provides ease of transferring sequences from commonly used pET-28a(+) into a vector compatible with the pBR322 family of plasmids. This essential need is currently not filled.

Sathiamoorthy, Sarmitha; Shin, Jumi A.

2012-01-01

385

Development of a New Sensorless-Vector-Controlled and Transmissionless Electric Vehicle Using a Permanent-Magnet Synchronous Motor  

NASA Astrophysics Data System (ADS)

One of the most important technologies for electric vehicles (EVs) will be drive control technology for main motor. It is desired for the drive control technology to have the following characteristics. 1) It does not require a position/speed sensor for controlling motor drive, which has been mounted on rotor shaft. 2) It is a kind of vector controls that can produce torque quickly, efficiently and/or precisely. 3) It has wide driving-range and allows developing EVs with no variable transmission. This paper proposes a total of new drive control technologies for such EVs using a permanent-magnet synchronous motor as a main motor, and verifies its usefulness through development of an actual EV that can drive on public road.

Shinnaka, Shinji; Takeuchi, Shigeru

386

Quantifying the mosquito's sweet tooth: modelling the effectiveness of attractive toxic sugar baits (ATSB) for malaria vector control  

PubMed Central

Background Current vector control strategies focus largely on indoor measures, such as long-lasting insecticide treated nets (LLINs) and indoor residual spraying (IRS); however mosquitoes frequently feed on sugar sources outdoors, inviting the possibility of novel control strategies. Attractive toxic sugar baits (ATSB), either sprayed on vegetation or provided in outdoor bait stations, have been shown to significantly reduce mosquito densities in these settings. Methods Simple models of mosquito sugar-feeding behaviour were fitted to data from an ATSB field trial in Mali and used to estimate sugar-feeding rates and the potential of ATSB to control mosquito populations. The model and fitted parameters were then incorporated into a larger integrated vector management (IVM) model to assess the potential contribution of ATSB to future IVM programmes. Results In the Mali experimental setting, the model suggests that about half of female mosquitoes fed on ATSB solution per day, dying within several hours of ingesting the toxin. Using a model incorporating the number of gonotrophic cycles completed by female mosquitoes, a higher sugar-feeding rate was estimated for younger mosquitoes than for older mosquitoes. Extending this model to incorporate other vector control interventions suggests that an IVM programme based on both ATSB and LLINs may substantially reduce mosquito density and survival rates in this setting, thereby substantially reducing parasite transmission. This is predicted to exceed the impact of LLINs in combination with IRS provided ATSB feeding rates are 50% or more of Mali experimental levels. In addition, ATSB is predicted to be particularly effective against Anopheles arabiensis, which is relatively exophilic and therefore less affected by IRS and LLINs. Conclusions These results suggest that high coverage with a combination of LLINs and ATSB could result in substantial reductions in malaria transmission in this setting. Further field studies of ATSB in other settings are needed to assess the potential of ATSB as a component in future IVM malaria control strategies.

2013-01-01

387

Establishment of a large semi-field system for experimental study of African malaria vector ecology and control in Tanzania  

PubMed Central

Background Medical entomologists increasingly recognize that the ability to make inferences between laboratory experiments of vector biology and epidemiological trends observed in the field is hindered by a conceptual and methodological gap occurring between these approaches which prevents hypothesis-driven empirical research from being conducted on relatively large and environmentally realistic scales. The development of Semi-Field Systems (SFS) has been proposed as the best mechanism for bridging this gap. Semi-field systems are defined as enclosed environments, ideally situated within the natural ecosystem of a target disease vector and exposed to ambient environmental conditions, in which all features necessary for its life cycle completion are present. Although the value of SFS as a research tool for malaria vector biology is gaining recognition, only a few such facilities exist worldwide and are relatively small in size (< 100 m2). Methods The establishment of a 625 m2 state-of-the-art SFS for large-scale experimentation on anopheline mosquito ecology and control within a rural area of southern Tanzania, where malaria transmission intensities are amongst the highest ever recorded, is described. Results A greenhouse frame with walls of mosquito netting and a polyethylene roof was mounted on a raised concrete platform at the Ifakara Health Institute. The interior of the SFS was divided into four separate work areas that have been set up for a variety of research activities including mass-rearing for African malaria vectors under natural conditions, high throughput evaluation of novel mosquito control and trapping techniques, short-term assays of host-seeking behaviour and olfaction, and longer-term experimental investigation of anopheline population dynamics and gene flow within a contained environment that simulates a local village domestic setting. Conclusion The SFS at Ifakara was completed and ready for use in under two years. Preliminary observations indicate that realistic and repeatable observations of anopheline behaviour are obtainable within the SFS, and that habitat and climatic features representative of field conditions can be simulated within it. As work begins in the SFS in Ifakara and others around the world, the major opportunities and challenges to the successful application of this tool for malaria vector research and control are discussed.

Ferguson, Heather M; Ng'habi, Kija R; Walder, Thomas; Kadungula, Demetrius; Moore, Sarah J; Lyimo, Issa; Russell, Tanya L; Urassa, Honorathy; Mshinda, Hassan; Killeen, Gerry F; Knols, Bart GJ

2008-01-01

388

Advanced solid rocket motor nozzle thrust vector control flexseal development status  

NASA Astrophysics Data System (ADS)

The advanced solid rocket motor (ASRM) flexseal development status is reviewed focusing on design goals and requirements, design configuration, analysis activities, and verification tests. It is concluded that the ASRM flexseal incorporates flight-proven materials in an innovative design configuration. Variable thickness shims and efficient packaging of the flexseal make it possible to achieve a significant weight reduction. A flexseal insulator design derived from strategic solid rocket motor experience will provide the necessary bearing thermal protection while minimizing vectoring torque variability.

Prins, William S.; Meyer, Scott A.; Cox, Paul D.

1992-07-01

389

QuikSCAT Radiometer (QRad) rain rates for wind vector quality control  

Microsoft Academic Search

The Sea Winds scatterometer onboard the QuikSCAT satellite measures the ocean normalized radar cross section to infer the surface wind vector. In addition, SeaWinds simultaneously measures the polarized microwave brightness temperature of the ocean\\/atmosphere, and this passive microwave measurement capability is known as the QuikSCAT Radiometer (QRad). QRad brightness temperatures are used to infer instantaneous rain rates over oceans using

K. A. Ahmad; W. Linwood Jones; T. Kasparis

2005-01-01

390

An agent–vector–host–environment model for controlling small arms and light weapons  

Microsoft Academic Search

Armed violence is a significant public health problem. It results in fatal and non-fatal injuries and disrupts social and economic processes that are essential to the health of individuals and communities. We argue that an agent–vector–host–environment model can be helpful in understanding and describing the availability and misuse of small arms and light weapons. Moreover, such a model can assist

Andrew D. Pinto; Malika Sharma; Robert Muggah

2011-01-01

391

Progress in directed energy control of vectors for microbes and other cells  

NASA Astrophysics Data System (ADS)

Biosynthetic semiconductor, diazoluminomelanin (DALM), is a polymer of tyrosine, luminol, and nitrite. DALM has a very large cross section of absorption for light from ultraviolet to radio frequencies. This polymer can be made efficiently in a genetically engineered E.coli, JM109/pIC2ORNR1.1 (ATCC# 69905). We have been pursuing ways to couple electromagnetic radiation to vectors using this polymer. DNA capture elements (DCEs; formerly aptamers) have made this possible. We incorporated DCEs into the plasmid of this E. coli to direct binding to whatever microbe or cell desired and to produce DALM attached to the plasmid DNA. Using two other vectors pSV2neoNR101 or pSV2neoNR8005 (ATCC # 69617 and 69618, respectively), both propagated in the E. coli host HB101, we have also inserted genes necessary for DALM production into animal and human cell lines (mouse monocytic leukemia: ATCC # CRL- 11771, -11772, -1173, mouse mammary adenocarcinoma: ATCC# CRL-12184, -12185; and human carcinoma of the cervix: ATCC # CRL-12510). The DCE/DALM vectors can be used to tag target cells, detectable by broad-spectrum light absorbance, luminescence, or fluorescence. DCE/DALM can further be activated with light, microwave energy, or by oxidative chemistry to kill the targeted microbes or other cells.

Kiel, Johnathan L.; Parker, Jill E.; Holwitt, Eric A.; Vivekananda, Jeeva; Sloan, Mark A.; Stribling, Lucille J. V.

2004-07-01

392

Applicability of the Generalized Integral Type PLL Method to Sensorless Vector Controls of Permanent Magnet Synchronous Motors Using Full-Order State Observer  

NASA Astrophysics Data System (ADS)

This paper newly shows applicability of the generalized integral type PLL method to sensorless vector controls of permanent magnet synchronous motors using full-order state observer, which have identified rotor speed as a system parameter separately from rotor phase treated as a system state by adaptive identification algorithm so far. The PLL method can exploit the integral-derivative relation between phase and speed, consequently can allow simpler realization of the sensorless vector controls.

Shinnaka, Shinji; I, Daisuke

393

Mosquito fauna and perspectives for integrated control of urban vector-mosquito populations in Southern Benin (West Africa).  

PubMed

This study aims at an integrated vector management (IVM) concept of implementing biological control agents against vector mosquito larvae as a cost-effective and scalable control strategy. In the first step, the mosquito species composition fauna of southern Benin was studied using standard entomological procedures in natural and man-made habitats. Altogether, 24 species belonging to 6 genera of mosquitoes Aedes, Anopheles, Culex, Mansonia, Uranotaenia, Ficalbia were recorded. Five species, Cx. thalassius, Cx. nebulosus, Cx. perfuscus, Cx. pocilipes and Fi. mediolineata are described the first time for Benin. The local mosquito species showed high susceptibility to a Bacillus sphaericus formulation (VectoLex(R) WDG ) in a standardized field test. A dosage of 1 g/m(2) was effective to achieve 100 percent mortality rate for Cx. quinquefasciatus late instar larvae in a sewage habitat, with a residual effect of up to 7 days. After more than 1 year of baseline data collection, operational larviciding with B. thuringiensis var. israelensis and B. sphaericus was commenced in 2006 in selected areas. Microbial insecticides products for larval control show great potential within IVM programmes and may augment control efforts against adult insects, such as the use of insecticide-treated bed nets or indoor wall spraying in many parts of Africa. PMID:20684480

Lingenfelser, Andre; Rydzanicz, Katarzyna; Kaiser, Achim; Becker, Norbert

2010-06-01

394

Simplified Vector Control with Adaptive Back-EMF Parameter Adjustment for Position Sensorless Permanent Magnet Synchronous Motors  

NASA Astrophysics Data System (ADS)

A previously reported vector control method for position sensorless permanent magnet synchronous motors involves the use of controllers with simple block configurations. However, the performance of this method can be affected by the erroneous setting of the motor parameters because a feedback compensator is not used. In this study, the effects of these errors on the steady-state performance of the drive control examined under various error conditions. It was found that the amplitude of the motor current increases when the parameter error is nonzero; the effect of the back-EMF parameter error was especially found to be large. On the basis of this observation, the use of a new compensator named “back-EMF parameter adjustment” is proposed. Simulation results and experimental results showed that the proposed method can compensate for the increase in the amplitude of the motor current resulting from the occurrence of motor parameter errors. A theoretical analysis showed that the performance of our vector control method, which involves the use of the new compensator, is affected only by errors in the d-axis inductance parameter Ld. Therefore, even if there are errors in the other motor parameters, the motor current for the constant load condition can be minimized by using the proposed method.

Sakamoto, Kiyoshi; Iwaji, Yoshitaka; Kaneko, Daigo; Takeuchi, Toshihiro; Endo, Tsunehiro; Kawamura, Atsuo

395

An alternative to killing? Treatment of reservoir hosts to control a vector and pathogen in a susceptible species.  

PubMed

Parasite-mediated apparent competition occurs when one species affects another through the action of a shared parasite. One way of controlling the parasite in the more susceptible host is to manage the reservoir host. Culling can cause issues in terms of ethics and biodiversity impacts, therefore we ask: can treating, as compared to culling, a wildlife host protect a target species from the shared parasite? We used Susceptible Infected Recovered (SIR) models parameterized for the tick-borne louping ill virus (LIV) system. Deer are the key hosts of the vector (Ixodes ricinus) that transmits LIV to red grouse Lagopus lagopus scoticus, causing high mortality. The model was run under scenarios of varying acaricide efficacy and deer densities. The model predicted that treating deer can increase grouse density through controlling ticks and LIV, if acaricide efficacies are high and deer densities low. Comparing deer treated with 70% acaricide efficacy with a 70% cull rate suggested that treatment may be more effective than culling if initial deer densities are high. Our results will help inform tick control policies, optimize the targeting of control methods and identify conditions where host management is most likely to succeed. Our approach is applicable to other host-vector-pathogen systems. PMID:22939093

Porter, R; Norman, R A; Gilbert, L

2012-09-03

396

False Positivity of Non-Targeted Infections in Malaria Rapid Diagnostic Tests: The Case of Human African Trypanosomiasis  

PubMed Central

Background In endemic settings, diagnosis of malaria increasingly relies on the use of rapid diagnostic tests (RDTs). False positivity of such RDTs is poorly documented, although it is especially relevant in those infections that resemble malaria, such as human African trypanosomiasis (HAT). We therefore examined specificity of malaria RDT products among patients infected with Trypanosoma brucei gambiense. Methodology/Principal Findings Blood samples of 117 HAT patients and 117 matched non-HAT controls were prospectively collected in the Democratic Republic of the Congo. Reference malaria diagnosis was based on real-time PCR. Ten commonly used malaria RDT products were assessed including three two-band and seven three-band products, targeting HRP-2, Pf-pLDH and/or pan-pLDH antigens. Rheumatoid factor was determined in PCR negative subjects. Specificity of the 10 malaria RDT products varied between 79.5 and 100% in HAT-negative controls and between 11.3 and 98.8% in HAT patients. For seven RDT products, specificity was significantly lower in HAT patients compared to controls. False positive reactions in HAT were mainly observed for pan-pLDH test lines (specificities between 13.8 and 97.5%), but also occurred frequently for the HRP-2 test line (specificities between 67.9 and 98.8%). The Pf-pLDH test line was not affected by false-positive lines in HAT patients (specificities between 97.5 and 100%). False positivity was not associated to rheumatoid factor, detected in 7.6% of controls and 1.2% of HAT patients. Conclusions/Significance Specificity of some malaria RDT products in HAT was surprisingly low, and constitutes a risk for misdiagnosis of a fatal but treatable infection. Our results show the importance to assess RDT specificity in non-targeted infections when evaluating diagnostic tests.

Gillet, Philippe; Mumba Ngoyi, Dieudonne; Lukuka, Albert; Kande, Viktor; Atua, Benjamin; van Griensven, Johan; Muyembe, Jean-Jacques; Jacobs, Jan; Lejon, Veerle

2013-01-01

397

Cultivation-Independent Methods Reveal Differences among Bacterial Gut Microbiota in Triatomine Vectors of Chagas Disease  

PubMed Central

Background Chagas disease is a trypanosomiasis whose agent is the protozoan parasite Trypanosoma cruzi, which is transmitted to humans by hematophagous bugs known as triatomines. Even though insecticide treatments allow effective control of these bugs in most Latin American countries where Chagas disease is endemic, the disease still affects a large proportion of the population of South America. The features of the disease in humans have been extensively studied, and the genome of the parasite has been sequenced, but no effective drug is yet available to treat Chagas disease. The digestive tract of the insect vectors in which T. cruzi develops has been much less well investigated than blood from its human hosts and constitutes a dynamic environment with very different conditions. Thus, we investigated the composition of the predominant bacterial species of the microbiota in insect vectors from Rhodnius, Triatoma, Panstrongylus and Dipetalogaster genera. Methodology/Principal Findings Microbiota of triatomine guts were investigated using cultivation-independent methods, i.e., phylogenetic analysis of 16s rDNA using denaturing gradient gel electrophoresis (DGGE) and cloned-based sequencing. The Chao index showed that the diversity of bacterial species in triatomine guts is low, comprising fewer than 20 predominant species, and that these species vary between insect species. The analyses showed that Serratia predominates in Rhodnius, Arsenophonus predominates in Triatoma and Panstrongylus, while Candidatus Rohrkolberia predominates in Dipetalogaster. Conclusions/Significance The microbiota of triatomine guts represents one of the factors that may interfere with T. cruzi transmission and virulence in humans. The knowledge of its composition according to insect species is important for designing measures of biological control for T. cruzi. We found that the predominant species of the bacterial microbiota in triatomines form a group of low complexity whose structure differs according to the vector genus.

da Mota, Fabio Faria; Marinho, Lourena Pinheiro; Moreira, Carlos Jose de Carvalho; Lima, Marli Maria; Mello, Cicero Brasileiro; Garcia, Eloi Souza; Carels, Nicolas; Azambuja, Patricia

2012-01-01

398

Centers for Disease Control light traps for monitoring Anopheles arabiensis human biting rates in an area with low vector density and high insecticide-treated bed net use.  

PubMed

Human landing catches (HLCs) are currently the preferred method to determine vector human biting rates (HBRs), which are key determinants of entomologic inoculation rates and important measures for assessing the impact of vector control efforts. Although HLCs are the most direct means of establishing HBRs, they are labor-intensive, and their use is facing increasing ethical concerns. The relationship between Centers for Disease Control (CDC) light traps and HLC collections was evaluated in Macha, Zambia during the 2007-2008 and 2008-2009 rainy seasons. A CDC light trap captured on average 1.91 (95% confidence interval = 1.16-2.28) times as many An. arabiensis per night as an indoor HLC. Additionally, nets treated with deltamethrin did not affect the numbers of An. arabiensis collected. Our results suggest that in regions where use of vector control interventions is high and vector densities are low, CDC light traps can be used to monitor An. arabiensis HBRs. PMID:20889876

Fornadel, Christen M; Norris, Laura C; Norris, Douglas E

2010-10-01

399

Centers for Disease Control Light Traps for Monitoring Anopheles arabiensis Human Biting Rates in an Area with Low Vector Density and High Insecticide-Treated Bed Net Use  

PubMed Central

Human landing catches (HLCs) are currently the preferred method to determine vector human biting rates (HBRs), which are key determinants of entomologic inoculation rates and important measures for assessing the impact of vector control efforts. Although HLCs are the most direct means of establishing HBRs, they are labor-intensive, and their use is facing increasing ethical concerns. The relationship between Centers for Disease Control (CDC) light traps and HLC collections was evaluated in Macha, Zambia during the 2007–2008 and 2008–2009 rainy seasons. A CDC light trap captured on average 1.91 (95% confidence interval = 1.16–2.28) times as many An. arabiensis per night as an indoor HLC. Additionally, nets treated with deltamethrin did not affect the numbers of An. arabiensis collected. Our results suggest that in regions where use of vector control interventions is high and vector densities are low, CDC light traps can be used to monitor An. arabiensis HBRs.

Fornadel, Christen M.; Norris, Laura C.; Norris, Douglas E.

2010-01-01

400

Diagnostic Accuracy of Loopamp Trypanosoma brucei Detection Kit for Diagnosis of Human African Trypanosomiasis in Clinical Samples  

PubMed Central

Background Molecular methods have great potential for sensitive parasite detection in the diagnosis of human African trypanosomiasis (HAT), but the requirements in terms of laboratory infrastructure limit their use to reference centres. A recently developed assay detects the Trypanozoon repetitive insertion mobile element (RIME) DNA under isothermal amplification conditions and has been transformed into a ready-to-use kit format, the Loopamp Trypanosoma brucei. In this study, we have evaluated the diagnostic performance of the Loopamp Trypanosoma brucei assay (hereafter called LAMP) in confirmed T.b. gambiense HAT patients, HAT suspects and healthy endemic controls from the Democratic Republic of the Congo (DRC). Methodology/Principal findings 142 T.b. gambiense HAT patients, 111 healthy endemic controls and 97 HAT suspects with unconfirmed status were included in this retrospective evaluation. Reference standard tests were parasite detection in blood, lymph or cerebrospinal fluid. Archived DNA from blood of all study participants was analysed in duplicate with LAMP. Sensitivity of LAMP in parasitologically confirmed cases was 87.3% (95% CI 80.9–91.8%) in the first run and 93.0% (95% CI 87.5–96.1%) in the second run. Specificity in healthy controls was 92.8% (95% CI 86.4–96.3%) in the first run and 96.4% (95% CI 91.1–98.6%) in the second run. Reproducibility was excellent with a kappa value of 0.81. Conclusions/Significance In this laboratory-based study, the Loopamp Trypanosoma brucei Detection Kit showed good diagnostic accuracy and excellent reproducibility. Further studies are needed to assess the feasibility of its routine use for diagnosis of HAT under field conditions.

Mitashi, Patrick; Hasker, Epco; Ngoyi, Dieudonne Mumba; Pyana, Pati Patient; Lejon, Veerle; Van der Veken, Wim; Lutumba, Pascal; Buscher, Philippe; Boelaert, Marleen; Deborggraeve, Stijn

2013-01-01

401

Parasite Prolyl Oligopeptidases and the Challenge of Designing Chemotherapeuticals for Chagas Disease, Leishmaniasis and African Trypanosomiasis  

PubMed Central

The trypanosomatids Trypanosoma cruzi, Leishmania spp. and Trypanosoma brucei spp. cause Chagas disease, leishmaniasis and human African trypanosomiasis, respectively. It is estimated that over 10 million people worldwide suffer from these neglected diseases, posing enormous social and economic problems in endemic areas. There are no vaccines to prevent these infections and chemotherapies are not adequate. This picture indicates that new chemotherapeutic agents must be developed to treat these illnesses. For this purpose, understanding the biology of the pathogenic trypanosomatid-host cell interface is fundamental for molecular and functional characterization of virulence factors that may be used as targets for the development of inhibitors to be used for effective chemotherapy. In this context, it is well known that proteases have crucial functions for both metabolism and infectivity of pathogens and are thus potential drug targets. In this regard, prolyl oligopeptidase and oligopeptidase B, both members of the S9 serine protease family, have been shown to play important roles in the interactions of pathogenic protozoa with their mammalian hosts and may thus be considered targets for drug design. This review aims to discuss structural and functional properties of these intriguing enzymes and their potential as targets for the development of drugs against Chagas disease, leishmaniasis and African trypanosomiasis.

Bastos, I.M.D; Motta, F.N; Grellier, P; Santana, J.M

2013-01-01

402

PCR based diagnosis of trypanosomiasis exploring invariant surface glycoprotein (ISG) 75 gene.  

PubMed

The invariant surface glycoprotein (ISG-75) gene of Trypanosoma evansi buffalo isolate from Karnataka state in India was sequenced and analyzed to elucidate its relationship with other isolates/species. The sequenced ISG-75 gene was also explored to device a polymerase chain reaction (PCR) strategy for the diagnosis of trypanosomiasis in carrier animals. The six cloned ISG gene sequences revealed the open reading frame (ORF) of 1572 and 1527 nucleotide (nt) encoding a polypeptide of 523 and 508 amino acids (aa) respectively and belongs ISG-75 gene family. Sequence analysis revealed 91-100% and 65-99% similarity at nt and aa levels, respectively with other isolates/species and belongs to the RoTat 1.2 strain. The diagnostic PCR based on ISG-75 sequence amplifies a 407 bp product specifically from the different T. evansi isolates and could detect 0.04 pg and 1.2 ng of DNA from purified trypanosomes and T. evansi infected rat blood samples respectively. Subsequently the PCR detected 0.02 and 0.27 trypanosomes ml(-1) respectively, from purified trypanosomes and T. evansi (buffalo isolate) infected rat blood. By the developed PCR assay trypanosomal nucleic acid was detected in experimental rats and buffalo on 24 h post infection (p.i.) and 3rd day post infection (d.p.i.), respectively. The developed ISG-75 gene based PCR assay could be useful in detection of carrier status of trypanosomiasis in animals. PMID:23305969

Rudramurthy, G R; Sengupta, P P; Balamurugan, V; Prabhudas, K; Rahman, H

2012-12-11

403

Molecular epidemiology of camel trypanosomiasis based on ITS1 rDNA and RoTat 1.2 VSG gene in the Sudan  

PubMed Central

Background Internal transcribed spacer one (ITS1) of the ribosomal DNA is known to be a suitable target for PCR-based detection of trypanosomes. The analysis of this region provides a multi-species-specific diagnosis by a single PCR. Using ITS1 primer-based PCR, a cross sectional study was carried out in the period from September to November 2009 on samples collected from 687 camels from geographically distinct zones in the Sudan to detect all possible African trypanosomes, which can infect camels. Results The results showed that all PCR-positive camels were infected with a single parasite species; Trypanosoma evansi. The highest prevalence, 57.1% (117/205), was observed in the Butana plains of mid-Eastern Sudan and the lowest, 6.0% (4/67), was in the Umshadeeda eastern part of White Nile State. In another experiment, the RoTat 1.2 gene encoding the variable surface glycoprotein (VSG) of T. evansi was analyzed for its presence or absence by a polymerase chain reaction (PCR) using T. evansi species-specific primers. The study showed that the RoTat 1.2 VSG gene was absent in thirteen out of thirty T. evansi-positive samples. Conclusions It is concluded that camel trypanosomiasis in Sudan is apparently caused by a single parasite species T. evansi and there were no other typanosomes species detected. In addition, the disease is highly prevalent in the country, which strengthens the need to change control policies and institute measures that help prevent the spread of the parasite. To our knowledge, this is the first molecular diagnosis report, which gives a picture of camel trypanosomiasis covering large geographical areas in Sudan.

2011-01-01

404

Vector Addition  

NSDL National Science Digital Library

This 2D applet simulates vector addition geometrically. The user selects the angle and magnitude of two vectors, which are then added together by the applet. The resultant vector and the values of its magnitude and angle, as well as the values of the x and y components of all three vectors, are calculated and displayed.

Duffy, Andrew

2004-11-28

405

Vector Calculator  

NSDL National Science Digital Library

A simple Java applet enabling users to add two two-dimensional vectors. The user can choose the two vectors by clicking on a grid. The components, magnitude, and direction are immediately shown. Once the two vectors are chosen, a press of a button shows the vector sum, its components, its magnitude and its direction.

Gea-Banacloche

2009-08-10

406

Molecular epidemiology of American trypanosomiasis in Brazil based on dimorphisms of rRNA and mini-exon gene sequences  

Microsoft Academic Search

American trypanosomiasis is transmitted in nature via a sylvatic cycle, where Trypanosoma cruzi interacts with wild triatomines and mammalian reservoirs, or via a domestic cycle where the parasite comes into contact with humans through domiciliated triatomines. The pool of T. cruzi isolates consists of sub-populations presenting a broad genetic diversity. In contrast to the heterogeneity suggested by isoenzyme analysis, PCR

B. Zingales; R. P. Souto; R. H. Mangia; C. V. Lisboa; D. A. Campbell; J. R. Coura; A. Jansen; O. Fernandes

1998-01-01

407

Neglected Diseases in the News: A Content Analysis of Recent International Media Coverage Focussing on Leishmaniasis and Trypanosomiasis  

Microsoft Academic Search

Background: Although the pharmaceutical industry's ''neglect'' of neglected tropical diseases (NTDs) has been investigated, no study evaluating media coverage of NTDs has been published. Poor media coverage exacerbates the neglect. This study aimed to investigate, describe, and analyse international media coverage of ''neglected diseases'' in general and three specific NTDs—African trypanosomiasis, leishmaniasis, and Chagas disease—from 1 January 2003 to 1

Mangai Balasegaram; Sooria Balasegaram; Denis Malvy; Pascal Millet

2008-01-01

408

Actigraphy in Human African Trypanosomiasis as a Tool for Objective Clinical Evaluation and Monitoring: A Pilot Study  

Microsoft Academic Search

BackgroundHuman African trypanosomiasis (HAT) or sleeping sickness leads to a complex neuropsychiatric syndrome with characteristic sleep alterations. Current division into a first, hemolymphatic stage and second, meningoencephalitic stage is primarily based on the detection of white blood cells and\\/or trypanosomes in the cerebrospinal fluid. The validity of this criterion is, however, debated, and novel laboratory biomarkers are under study. Objective

Alfred K. Njamnshi; Paul F. Seke Etet; Stephen Perrig; Alphonse Acho; Julius Y. Funsah; Dieudonné Mumba; Jean-Jacques Muyembe; Krister Kristensson; Marina Bentivoglio

2012-01-01

409

Treatment and follow-up of the first case of human trypanosomiasis caused by Trypanosoma evansi in India.  

PubMed

The first reported human case of trypanosomiasis caused by Trypanosoma evansi was treated using suramin. Patient follow-up indicates that the drug and specific regimen used were well tolerated. Clinical, serological and parasitological investigations at 6 months indicate complete cure of the patient. Suramin should be considered in the treatment of other cases of human T. evansi infection, if they occur. PMID:16455122

Joshi, P P; Chaudhari, A; Shegokar, V R; Powar, R M; Dani, V S; Somalwar, A M; Jannin, J; Truc, P

2006-02-07

410

The effect of 7-8 years of vector control on the evolution of ocular onchocerciasis in West African savanna.  

PubMed

The evolution of ocular onchocerciasis was studied in a cohort of 1170 persons over 5 years of age who were examined before the start of and after 7-8 years of effective vector control in 12 originally hyperendemic villages in the central part of the OCP area. The proportion of the cohort which at the outset of vector control was free from ocular onchocerciasis or had an early or recent infection in the form of punctate keratitis only, remained largely free of or lost their signs of ocular infection respectively and only a very insignificant proportion acquired microfilariae in the eyes or developed a severe onchocercal eye lesion at the initial stage. The proportion of the cohort with a heavy ocular microfilarial load had a reduced risk of developing severe eye lesions and no risk of going blind. The proportion of the cohort with already existing severe eye lesions at the advanced stage remained largely unchanged and some lesions at the initial stage disappeared. Blindness occurred only in those who had severe eye lesions at the outset and was comparatively less than in areas of on-going transmission. PMID:3787122

Dadzie, K Y; Remme, J; Rolland, A; Thylefors, B

1986-09-01

411

wFlu: Characterization and Evaluation of a Native Wolbachia from the Mosquito Aedes fluviatilis as a Potential Vector Control Agent  

PubMed Central

There is currently considerable interest and practical progress in using the endosymbiotic bacteria Wolbachia as a vector control agent for human vector-borne diseases. Such vector control strategies may require the introduction of multiple, different Wolbachia strains into target vector populations, necessitating the identification and characterization of appropriate endosymbiont variants. Here, we report preliminary characterization of wFlu, a native Wolbachia from the neotropical mosquito Aedes fluviatilis, and evaluate its potential as a vector control agent by confirming its ability to cause cytoplasmic incompatibility, and measuring its effect on three parameters determining host fitness (survival, fecundity and fertility), as well as vector competence (susceptibility) for pathogen infection. Using an aposymbiotic strain of Ae. fluviatilis cured of its native Wolbachia by antibiotic treatment, we show that in its natural host wFlu causes incomplete, but high levels of, unidirectional cytoplasmic incompatibility, has high rates of maternal transmission, and no detectable fitness costs, indicating a high capacity to rapidly spread through host populations. However, wFlu does not inhibit, and even enhances, oocyst infection with the avian malaria parasite Plasmodium gallinaceum. The stage- and sex-specific density of wFlu was relatively low, and with limited tissue distribution, consistent with the lack of virulence and pathogen interference/symbiont-mediated protection observed. Unexpectedly, the density of wFlu was also shown to be specifically-reduced in the ovaries after bloodfeeding Ae. fluviatilis. Overall, our observations indicate that the Wolbachia strain wFlu has the potential to be used as a vector control agent, and suggests that appreciable mutualistic coevolution has occurred between this endosymbiont and its natural host. Future work will be needed to determine whether wFlu has virulent host effects and/or exhibits pathogen interference when artificially-transfected to the novel mosquito hosts that are the vectors of human pathogens.

Goncalves, Daniela da Silva; Moreira, Luciano Andrade

2013-01-01

412

Helper Virus-Free, Optically Controllable, and Two-Plasmid-Based Production of Adeno-associated Virus Vectors of Serotypes 1 to 6  

Microsoft Academic Search

We present a simple and safe strategy for producing high-titer adeno-associated virus (AAV) vectors derived from six different AAV serotypes (AAV-1 to AAV-6). The method, referred to as “HOT,” is helper virus free, optically controllable, and based on transfection of only two plasmids, i.e., an AAV vector construct and one of six novel AAV helper plasmids. The latter were engineered

Dirk Grimm; Mark A. Kay; Juergen A. Kleinschmidt

2003-01-01

413

Stoking the drug target pipeline for human African trypanosomiasis  

PubMed Central

Trypanosoma brucei is the causative agent of African sleeping sickness, putting at risk up to 50 million people in sub-Saharan Africa. Current drug therapies are limited by toxicity and difficult treatment regimes and as the development of vaccines remains unlikely, the identification of better drugs to control this deadly disease is needed. Strategies for the identification of new lead compounds include phenotypic screening or target-based approaches. Implementation of the latter has been hampered by the lack of defined targets that are both essential and druggable. In this issue of Molecular Microbiology, Jones et al. report on the characterization of T. brucei pyridoxal kinase (PdxK), an enzyme required for the salvage of vitamin B6, an essential enzymatic cofactor. Genetic knockdown and small molecule inhibitor studies were used to demonstrate that PdxK is essential for parasite growth both in vitro and in a mouse model, providing both genetic and chemical validation of the target. An enzyme assay compatible with high throughput screening (HTS) was developed and the X-ray crystal structure solved, showing the potential for species selective inhibition. These studies add a greatly needed additional target into the drug discovery pipeline for this deadly parasitic infection.

Phillips, Margaret A.

2012-01-01

414

Modified vector control algorithm for increasing partial-load efficiency of fractional-slot concentrated-winding surface PM machines  

SciTech Connect

This paper presents a modified vector control algorithm for a fractional-slot concentrated-winding surface PM machine that has been developed to maximize the machine's partial-load efficiency over a wide range of operating conditions. By increasing the amplitude of the negative d-axis current, the resulting increase in the stator copper losses can be more than offset by the reduction in the iron core losses achieved by lowering the stator d-axis flux amplitude. The effectiveness of this technique has been demonstrated using both analytical models and finite element analysis (FEA) for a 55 kW (peak) surface PM machine design developed for a demanding set of traction drive performance requirements. For this example, the modified control strategy increases the partial-load efficiency at 20% of rated torque by >6% at 2000 rpm compared to the maximum torque/amp algorithm, making the machine much more attractive for its intended application

El-Refaie, Ayman M [ORNL; Jahns, Thomas M [ORNL; Reddy, Patel [University of Wisconsin; McKeever, John W [ORNL

2006-01-01

415

[Social representations concerning dengue, dengue vectors, and control activities among residents of São Sebastião on the northern coast of São Paulo State, Brazil].  

PubMed

This study sought to identify people's knowledge on dengue and its vector biology, aimed at promoting a communications channel between technical and lay reasoning in order to foster community involvement in dengue and dengue vector control activities. A survey was conducted in an Aedes aegypti-infested area with dengue transmission in São Sebastião on the northern coast of São Paulo State, Brazil. One hundred interviews were held, with five open questions on topics related to dengue and vector control. Collective Subject Discourse methodology was used in the analysis. People were not able to properly identify the kinds of accumulated water sources that serve as breeding places for mosquitoes and were unaware of the egg phase in vector development. There was inadequate awareness of vector biology and a need for greater government-community integration. Educational activities should incorporate the study results as insight for improving the social efficiency and efficacy of joint actions to fight dengue and control the mosquito vector. PMID:17572820

Lefèvre, Ana Maria Cavalcanti; Ribeiro, Andressa Francisca; Marques, Gisela Rita de Alvarenga Monteiro; Serpa, Lígia Leandro Nunes; Lefèvre, Fernando

2007-07-01

416

Efficacy of Aquatain, a Monomolecular Film, for the Control of Malaria Vectors in Rice Paddies  

Microsoft Academic Search

BackgroundRice paddies harbour a large variety of organisms including larvae of malaria mosquitoes. These paddies are challenging for mosquito control because their large size, slurry and vegetation make it difficult to effectively apply a control agent. Aquatain, a monomolecular surface film, can be considered a suitable mosquito control agent for such breeding habitats due to its physical properties. The properties

Tullu Bukhari; Willem Takken; Andrew K. Githeko; Constantianus J. M. Koenraadt; Georges Snounou

2011-01-01

417

Prevalence and under-detection of gambiense human African trypanosomiasis during mass screening sessions in Uganda and Sudan  

PubMed Central

Background Active case detection through mass community screening is a major control strategy against human African trypanosomiasis (HAT, sleeping sickness) caused by T. brucei gambiense. However, its impact can be limited by incomplete attendance at screening sessions (screening coverage) and diagnostic inaccuracy. Methods We developed a model-based approach to estimate the true prevalence and the fraction of cases detected during mass screening, based on observed prevalence, and adjusting for incomplete screening coverage and inaccuracy of diagnostic algorithms for screening, confirmation and HAT stage classification. We applied the model to data from three Médecins Sans Frontières projects in Uganda (Adjumani, Arua-Yumbe) and Southern Sudan (Kiri). Results We analysed 604 screening sessions, targeting about 710 000 people. Cases were about twice as likely to attend screening as non-cases, with no apparent difference by stage. Past incidence, population size and repeat screening rounds were strongly associated with observed prevalence. The estimated true prevalence was 0.46% to 0.90% in Kiri depending on the analysis approach, compared to an observed prevalence of 0.45%; 0.59% to 0.87% in Adjumani, compared to 0.92%; and 0.18% to 0.24% in Arua-Yumbe, compared to 0.21%. The true ratio of stage 1 to stage 2 cases was around two-three times higher than that observed, due to stage misclassification. The estimated detected fraction was between 42.2% and 84.0% in Kiri, 52.5% to 79.9% in Adjumani and 59.3% to 88.0% in Arua-Yumbe. Conclusions In these well-resourced projects, a moderate to high fraction of cases appeared to be detected through mass screening. True prevalence differed little from observed prevalence for monitoring purposes. We discuss some limitations to our model that illustrate several difficulties of estimating the unseen burden of neglected tropical diseases.

2012-01-01

418

Population Size and Migration of Anopheles gambiae in the Bancoumana Region of Mali and Their Significance for Efficient Vector Control  

PubMed Central

We present results of two intensive mark-release-recapture surveys conducted during the wet and dry seasons of 2008 in the villages of Fourda and Kenieroba, Mali. The former is a small fishing village by the Niger River with a moderate to high densities of Anopheles gambiae Giles s.s. (Diptera: Culicidae) throughout the year, while the latter is a large agricultural community 2 km inland that experiences strong seasonal fluctuation in An. gambiae densities. We estimate the population size of female An. gambiae in Fourda to be in less than 3,000 during the dry season. We found evidence of large population size and migration from Fourda in Kenieroba during the wet season, but very low numbers and no sign of migrants during the dry season. We suggest that malaria vector control measures aimed at adult mosquitoes might be made more efficient in this region and other seasonal riparian habitats by targeting disruption of mosquito populations by the river during the dry season. This would decrease the size of an already small population, and would be likely to delay the explosive growth in vector numbers in the larger inland villages as rainfall increases.

Baber, Ibrahima; Keita, Moussa; Sogoba, Nafomon; Konate, Mamadou; Diallo, M'Bouye; Doumbia, Seydou; Traore, Sekou F.; Ribeiro, Jose M. C.; Manoukis, Nicholas C.

2010-01-01

419

Population size and migration of Anopheles gambiae in the Bancoumana Region of Mali and their significance for efficient vector control.  

PubMed

We present results of two intensive mark-release-recapture surveys conducted during the wet and dry seasons of 2008 in the villages of Fourda and Kenieroba, Mali. The former is a small fishing village by the Niger River with a moderate to high densities of Anopheles gambiae Giles s.s. (Diptera: Culicidae) throughout the year, while the latter is a large agricultural community 2 km inland that experiences strong seasonal fluctuation in An. gambiae densities. We estimate the population size of female An. gambiae in Fourda to be in less than 3,000 during the dry season. We found evidence of large population size and migration from Fourda in Kenieroba during the wet season, but very low numbers and no sign of migrants during the dry season. We suggest that malaria vector control measures aimed at adult mosquitoes might be made more efficient in this region and other seasonal riparian habitats by targeting disruption of mosquito populations by the river during the dry season. This would decrease the size of an already small population, and would be likely to delay the explosive growth in vector numbers in the larger inland villages as rainfall increases. PMID:20422013

Baber, Ibrahima; Keita, Moussa; Sogoba, Nafomon; Konate, Mamadou; Diallo, M'Bouye; Doumbia, Seydou; Traoré, Sékou F; Ribeiro, José M C; Manoukis, Nicholas C

2010-04-21

420

Current Control for AC Motor Drives Using a Single DC-Link Current Sensor and Measurement Voltage Vectors  

Microsoft Academic Search

A new algorithm using a single dc-link current sensor to reconstruct all three inverter phase currents has been proposed that overcomes problems caused by the presence of regions in the voltage vector plane where the phase currents are not conveniently measurable. The measurement vector insertion method (MVIM) achieves this objective by applying additional active voltage vectors for brief intervals only

Hongrae Kim; Thomas M. Jahns

2006-01-01

421

Dynamics of the "popcorn" Wolbachia infection in outbred Aedes aegypti informs prospects for mosquito vector control.  

PubMed

Forty percent of the world's population is at risk of contracting dengue virus, which produces dengue fever with a potentially fatal hemorrhagic form. The wMelPop Wolbachia infection of Drosophila melanogaster reduces life span and interferes with viral transmission when introduced into the mosquito Aedes aegypti, the primary vector of dengue virus. Wolbachia has been proposed as an agent for preventing transmission of dengue virus. Population invasion by Wolbachia depends on levels of cytoplasmic incompatibility, fitness effects, and maternal transmission. Here we characterized these traits in an outbred genetic background of a potential target population of Ae. aegypti using two crossing schemes. Cytoplasmic incompatibility was strong in this background, and the maternal transmission rate of Wolbachia was high. The infection substantially reduced longevity of infected adult females, regardless of whether adults came from larvae cultured under high or low levels of nutrition or density. The infection reduced the viability of diapausing and nondiapausing eggs. Viability was particularly low when eggs were laid by older females and when diapausing eggs had been stored for a few weeks. The infection affected mosquito larval development time and adult body size under different larval nutrition levels and densities. The results were used to assess the potential for wMelPop-CLA to invade natural populations of Ae. aegypti and to develop recommendations for the maintenance of fitness in infected mosquitoes that need to compete against field insects. PMID:21135075

Yeap, H L; Mee, P; Walker, T; Weeks, A R; O'Neill, S L; Johnson, P; Ritchie, S A; Richardson, K M; Doig, C; Endersby, N M; Hoffmann, A A

2010-12-06

422

Estimated optimum control of a spacecraft by the rocket engine thrust vector at the extraatmospheric section of the reentry of an artificial earth satellite  

Microsoft Academic Search

The paper investigates optimal, minimum-fuel control of a spacecraft by the rocket engine thrust vector on the extraatmospheric section of the reentry of a satellite. The control design, which provides for firing of the engine twice, is shown to be highly efficient. A high-speed algorithm is developed for calculating the estimated optimum reentry trajectories to the prescribed area of the

N. L. Sokolov; A. P. Sokolov; T. Iu. Smirnova

1992-01-01

423

Society for Vector Ecology  

NSDL National Science Digital Library

Formed in 1968, the Society for Vector Ecology (SOVE) is dedicated to studying "all aspects of the biology, ecology, and control of arthropod vectors and the interrelationships between the vectors and the disease agents they transmit." Comprised of researchers and operational and extension personnel around the globe, SOVE tracks and studies the biological organisms that transmit diseases. The SOVE Website contains information related to the Society (e.g., mission, history), its publications (journal, newsletter -- both .pdf format), and professional opportunities (conferences, employment). Several dozen links to additional vector ecology resources are provided.

2002-01-01

424

New Support Vector Algorithms  

Microsoft Academic Search

We propose a new class of support vector algorithms for regression and classification. In these algorithms, a parameter ? lets one effectively control the number of support vectors. While this can be useful in its own right, the parameterization has the additional benefit of enabling us to eliminate one of the other free parameters of the algorithm: the accuracy parameter

Bernhard Schölkopf; Alex J. Smola; Robert C. Williamson; Peter L. Bartlett

2000-01-01

425

New drugs for the treatment of human African trypanosomiasis: research and development.  

PubMed

Chemotherapy of human African trypanosomiasis is problematic because of the high frequency of severe adverse events, the long duration and high cost of treatment, and an increasing number of treatment-refractory cases. New cost-efficient, easy-to-use drugs are urgently needed. Whereas basic research on potential drug targets is anchored in academia, the complex, highly regulated and very expensive process of preclinical and clinical drug development is almost exclusively in the hands of pharmaceutical companies. Jennifer Keiser, August Stich and Christian Burri here review, from the angle of industrial drug research and development, the past ten years of research activities at different stages of the development of trypanocidal drugs, and assess future prospects. The absence of compounds in clinical development Phases I-III indicates no new drugs will become available in the next few years. PMID:11137740

Keiser, J; Stich, A; Burri, C

2001-01-01

426

Parasitic Central Nervous System Infections in Immunocompromised Hosts: Malaria, Microsporidiosis, Leishmaniasis, and African Trypanosomiasis  

PubMed Central

Immunosuppression associated with HIV infection or following transplantation increases susceptibility to central nervous system (CNS) infections. Because of increasing international travel, parasites that were previously limited to tropical regions pose an increasing infectious threat to populations at risk for acquiring opportunistic infection, especially people with HIV infection or individuals who have received a solid organ or bone marrow transplant. Although long-term immunosuppression caused by medications such as prednisone likely also increases the risk for acquiring infection and for developing CNS manifestations, little published information is available to support this hypothesis. In an earlier article published in Clinical Infectious Diseases, we described the neurologic manifestations of some of the more common parasitic CNS infections. This review will discuss the presentation, diagnosis, and treatment of the following additional parasitic CNS infections: malaria, microsporidiosis, leishmaniasis, and African trypanosomiasis.

Walker, Melanie; Kublin, James G.; Zunt, Joseph R.

2009-01-01

427

New insights in staging and chemotherapy of African trypanosomiasis and possible contribution of medicinal plants.  

PubMed

Human African trypanosomiasis (HAT) is a fatal if untreated fly-borne neuroinflammatory disease caused by protozoa of the species Trypanosoma brucei (T.b.). The increasing trend of HAT cases has been reversed, but according to WHO experts, new epidemics of this disease could appear. In addition, HAT is still a considerable burden for life quality and economy in 36 sub-Saharan Africa countries with 15-20 million persons at risk. Following joined initiatives of WHO and private partners, the fight against HAT was re-engaged, resulting in considerable breakthrough. We present here what is known at this day about HAT etiology and pathogenesis and the new insights in the development of accurate tools and tests for disease staging and severity monitoring in the field. Also, we elaborate herein the promising progresses made in the development of less toxic and more efficient trypanocidal drugs including the potential of medicinal plants and related alternative drug therapies. PMID:22593674

Seke Etet, Paul F; Mahomoodally, M Fawzi

2012-04-19

428

Neural network based estimation of feedback signals for a vector controlled induction motor drive  

Microsoft Academic Search

Neural networks are showing promise for application in power electronics and motion control systems. So far, they have been applied for a few cases, mainly in the control of converters and drives, but their application in estimation is practically new. The purpose of this paper is to demonstrate that such a technology can be applied for estimation of feedback signals

M. Godoy Simces; Bimal K. Bose

1995-01-01

429

Investigation on vector control of three-phase synchronous machines under supply fault condition  

Microsoft Academic Search

This paper deals with modeling and control of a three-phase permanent magnet synchronous machine (PMSM) with sinusoidal back electromotive forces (emf) under supply fault conditions. The overall system is modeled thanks to the energetic macroscopic representation (EMR) formalism considering that a fusible element opens the phase circuit. Using systematic inversion rules of the EMR, a maximum control structure (MCS) is

Y. Crevits; X. Kestelyn; E. Semail

2006-01-01

430

An Improved Sliding Mode Observer for Speed Sensorless Vector Control Drive of PMSM  

Microsoft Academic Search

This paper proposes a speed sensorless control scheme for permanent magnet synchronous motor (PMSM) drive using an improved sliding mode observer (SMO). A variable frequency or cutoff frequency in low pass filter is not essential to use in the improved SMO. Since the product of the improved SMO gain and the control action of sigmoid function, which replaces the Bang-Bang

K. Paponpen; M. Konghirun

2006-01-01

431

A PC-based architecture for parameter analysis of vector-controlled induction motor drive  

Microsoft Academic Search

In this article a methodology for constructing a user interface for system control and data acquisition of a drive which is suitable for three-phase induction motors (3?IM) is presented. The entire hardware implementation is shown, including power and digital stages. Communication between the computer and the controller is engaged in order to enhance an analysis of power quality, adjust the

Carlos A. Gonzalez-Gutierrez; Juvenal Rodriguez-Resendiz; Georgina Mota-Valtierra; Edgar A. Rivas-Araiza; Jorge D. Mendiola-Santibañez; Ricardo Luna-Rubio

432

Early biting rhythm in the Afro-tropical vector of malaria, Anopheles arabiensis, and challenges for its control in Ethiopia.  

PubMed

The biting cycle of the malaria vector Anopheles arabiensis Patton (Diptera: Culicidae) was assessed by hourly light trap collections in three villages in Tigray, northern Ethiopia. Hourly catches were conducted in two houses in each village, for four consecutive nights. Light traps were set from 18.00 hours to 07.00 hours in houses in which people slept under untreated bednets. Anopheles arabiensis showed early biting activities, which peaked between 19.00 hours and 20.00 hours in the three villages; over 70% of biting activity occurred before 22.00 hours, when people typically retire to bed. This early biting activity may have a negative impact on the efficiency of bednets to control malaria. PMID:21410494

Yohannes, M; Boelee, E

2011-03-16

433

Monitoring of larval habitats and mosquito densities in the Sudan savanna of Mali: implications for malaria vector control.  

PubMed

In Mali, anopheline mosquito populations increase sharply during the rainy season, but are barely detectable in the dry season. This study attempted to identify the dry season mosquito breeding population in and near the village of Bancoumana, Mali, and in a fishing hamlet 5 km from this village and adjacent to the Niger River. In Bancoumana, most larval habitats were human made, and dried out in January-February. In contrast, in the fishing hamlet, productive larval habitats were numerous and found mainly during the dry season (January-May) as the natural result of drying riverbeds. Adult mosquitoes were abundant during the dry season in the fishermen hamlet and rare in Bancoumana. To the extent that the fishermen hamlet mosquito population seeds Bancoumana with the advent of the rainy season, vector control in this small hamlet may be a cost-effective way to ameliorate malaria transmission in the 40-times larger village. PMID:17620634

Sogoba, Nafomon; Doumbia, Seydou; Vounatsou, Penelope; Baber, Ibrahima; Keita, Moussa; Maiga, Mamoudou; Traoré, Sékou F; Touré, Abdoulaye; Dolo, Guimogo; Smith, Thomas; Ribeiro, José M C

2007-07-01

434

Insecticide resistance in Bemisia tabaci Gennadius (Homoptera: Aleyrodidae) and Anopheles gambiae Giles (Diptera: Culicidae) could compromise the sustainability of malaria vector control strategies in West Africa.  

PubMed

Insecticides from the organophosphate (OP) and pyrethroid (PY) chemical families, have respectively, been in use for 50 and 30 years in West Africa, mainly against agricultural pests, but also against vectors of human disease. The selection pressure, with practically the same molecules year after year (mainly on cotton), has caused insecticide resistance in pest populations such as Bemisia tabaci, vector of harmful phytoviruses on vegetables. The evolution toward insecticide resistance in malaria vectors such as Anopheles gambiae sensus lato (s.l.) is probably related to the current use of these insecticides in agriculture. Thus, successful pest and vector control in West Africa requires an investigation of insect susceptibility, in relation to the identification of species and sub species, such as molecular forms or biotypes. Identification of knock down resistance (kdr) and acetylcholinesterase gene (Ace1) mutations modifying insecticide targets in individual insects and measure of enzymes activity typically involved in insecticide metabolism (oxidase, esterase and glutathion-S-transferase) are indispensable in understanding the mechanisms of resistance. Insecticide resistance is a good example in which genotype-phenotype links have been made successfully. Insecticides used in agriculture continue to select new resistant populations of B. tabaci that could be from different biotype vectors of plant viruses. As well, the evolution of insecticide resistance in An. gambiae threatens the management of malaria vectors in West Africa. It raises the question of priority in the use of insecticides in health and/or agriculture, and more generally, the question of sustainability of crop protection and vector control strategies in the region. Here, we review the susceptibility tests, biochemical and molecular assays data for B. tabaci, a major pest in cotton and vegetable crops, and An. gambiae, main vector of malaria. The data reviewed was collected in Benin and Burkina Faso between 2008 and 2010 under the Corus 6015 research program. This review aims to show: (i) the insecticide resistance in B. tabaci as well as in An. gambiae; and (ii) due to this, the impact of selection of resistant populations on malaria vector control strategies. Some measures that could be beneficial for crop protection and vector control strategies in West Africa are proposed. PMID:23792227

Gnankiné, Olivier; Bassolé, Imael H N; Chandre, Fabrice; Glitho, Isabelle; Akogbeto, Martin; Dabiré, Roch K; Martin, Thibaud

2013-06-17

435

Vector Voyage!  

NSDL National Science Digital Library

In this activity, students will use vector analysis to understand the concept of dead reckoning. Students will use vectors to plot their course based on a time and speed. They will then correct the positions with vectors representing winds and currents.

Integrated Teaching And Learning Program

436

A support vector brain-machine interface for cortical control of directions  

Microsoft Academic Search

A closed-loop brain-machine interface system (BMI) was implemented using freely-moving rats. Instead of reproducing continuous natural limb movements as in many other BMI work, abstract supervisory control commands such as Go left, Go right, were extracted from neurons in the motor and premotor areas of the rats brain. The control output was thus formulated as a solution of a nonlinear

Jing Hu; Jennie Si; Byron Olson; Jiping He

2006-01-01

437

Transgenic Vegetables and Fruits for Control of Insects and Insect-Vectored Pathogens  

Microsoft Academic Search

Fruits and vegetables are major components of a healthy diet, but are subject to severe pest pressure. Approximately 30% of\\u000a all insecticides applied worldwide are used to control insects affecting vegetables and fruits. Transgenic, or more commonly\\u000a referred to as genetically modified (GM), vegetables and fruits offer unique opportunities for controlling insects and the\\u000a pathogens they transmit. Aphid transmitted viruses

Anthony M. Shelton; Marc Fuchs; Frank A. Shotkoski

438

Blood-feeding behaviour of the malarial mosquito Anopheles arabiensis: implications for vector control.  

PubMed

Feeding behaviour of the malaria vector Anopheles arabiensis Patton (Diptera: Culicidae) was monitored for 12 months (March 2003-February 2004) in the Konso District of southern Ethiopia (5 degrees 15'N, 37 degrees 28'E). More than 45 000 An. arabiensis females were collected by host-baited sampling methods (light-traps, human landing catches, cattle-baited traps) and from resting sites (huts and pit shelters). In the village of Fuchucha, where the ratio of cattle : humans was 0.6 : 1, 51% of outdoor-resting mosquitoes and 66% of those collected indoors had fed on humans, human baits outdoors caught > 2.5 times more mosquitoes than those indoors and the mean catch of mosquitoes from pit shelters was about five times that from huts. Overall, the vast majority of feeding and resting occurred outdoors. In the cattle camps of Konso, where humans slept outdoors close to their cattle, approximately 46% of resting mosquitoes collected outdoors had fed on humans despite the high cattle : human ratio (17 : 1). In both places, relatively high proportions of bloodmeals were mixed cow + human: 22-25% at Fuchucha and 37% in the cattle camps. Anthropophily was also gauged experimentally by comparing the numbers of mosquitoes caught in odour-baited entry traps baited with either human or cattle odour. The human-baited trap caught about five times as many mosquitoes as the cattle-baited one. Notwithstanding the potential pitfalls of using standard sampling devices to analyse mosquito behaviour, the results suggest that the An. arabiensis population is inherently anthropophagic, but this is counterbalanced by exophagic and postprandial exophilic tendencies. Consequently, the population feeds sufficiently on humans to transmit malaria (sporozoite rates: 0.3% for Plasmodium falciparum and 0.5% for P. vivax, by detection of circumsporozoite antigen) but also takes a high proportion of meals from non-human hosts, with 59-91% of resting mosquitoes containing blood from cattle. Hence, classical zooprophylaxis is unlikely to have a significant impact on the malaria vectorial capacity of An. arabiensis in Konso, whereas treating cattle with insecticide might do. PMID:17199754

Tirados, I; Costantini, C; Gibson, G; Torr, S J

2006-12-01

439

The fog of war: why the environmental crusade for anadromous fish species in California could disarm the state's local vector control districts in their war against mosquitoes.  

PubMed

In California, local mosquito and vector control districts have successfully controlled mosquito and vector-borne diseases by improving drainage patterns and applying pesticides. The Bay-Delta Conservation Plan, which is a proposed habitat conservation plan for the Sacramento-San Joaquin Bay-Delta estuary, proposes to add over 70,000 acres of habitat in the Delta to improve conditions for threatened and endangered aquatic and terrestrial species. This habitat could also be a suitable mosquito breeding habitat, which will be located in close proximity to urban and suburban communities. Wetland management practices and continued pesticide applications in the Delta could mitigate the effects of a new mosquito breeding habitat. Recent legal developments, however, require districts to obtain and comply with Clean Water Act permits, which restrict the application of pesticides in or near waters of the United States. Moreover, the U.S. Environmental Protection Agency has taken the first step in a rulemaking process that could further limit or prohibit the use of certain vector control pesticides in the Delta. In the near term and until less harmful methods for mosquito control are available, local vector control districts' application of mosquito control pesticides should be exempt from Clean Water Act permit requirements. PMID:23856372

Siptroth, Stephen M; Shanahan, Richard P

2011-07-28

440

Development and evaluation of a pyriproxyfen-treated device to control the dengue vector, Aedes aegypti (L.) (Diptera:Culicidae).  

PubMed

The resurgence of dengue fever and the chikungunya epidemic make the control of Aedes aegypti mosquitoes, the vectors of these diseases, critically important. We developed and evaluated an Ae. aegypti control device that is visually-attractive to mosquitoes. This pyriproxyfen-treated device was evaluated for its impact on Ae. aegypti egg production and population dynamics in dengue-endemic areas in Thailand. The device consists of a "high rise" shaped ovitrap/ resting station covered with black cotton cloth. The device is easily collapsible and transportable. Ae. aegypti are generally drawn towards darker, shadier areas making this device physically attractive as a resting station to mosquitoes of all physiological stages. The results show this device suppressed Ae. aegypti populations after it was introduced into a village. The observed effect was primarily the result of the Ae. aegypti exposure to pyriproxyfen shortly after adult emergence or after taking a blood meal resulting in decreased egg production. We believe the device may be further improved physically and the formulation should be replaced to provide even better efficacy for controlling Ae. aegypti mosquito, populations. PMID:23691625

Ponlawat, Alongkot; Fansiri, Thanyalak; Kurusarttra, Somwang; Pongsiri, Arissara; McCardle, Patrick W; Evans, Brian P; Evans, Brain P; Richardson, Jason H

2013-03-01