Sample records for trypanosomiasis vector control

  1. Trypanosomiasis vector control in Africa and Latin America

    PubMed Central

    Schofield, Chris J; Kabayo, John P

    2008-01-01

    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 administrative boundaries. In this review we present the underlying rationale, operational background and progress of the various trypanosomiasis vector control initiatives active in both continents. PMID:18673535

  2. Shifting priorities in vector biology to improve control of vector-borne disease

    E-print Network

    , dengue, trypanosomiasis, filariasis, leishmaniasis, and Chagas disease. Current control strategies, trypanosomiasis, filariasis, leishmaniasis, and Chagas disease (Gubler 1998). History shows that vector control

  3. HUMAN/VECTOR RELATIONSHIPS DURING HUMAN AFRICAN TRYPANOSOMIASIS: INITIAL SCREENING OF IMMUNOGENIC SALIVARY

    E-print Network

    Paris-Sud XI, Université de

    HUMAN/VECTOR RELATIONSHIPS DURING HUMAN AFRICAN TRYPANOSOMIASIS: INITIAL SCREENING OF IMMUNOGENIC immunogenic proteins in humans residing in an area endemic for human African trypanosomiasis in the Democratic

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

    PubMed Central

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

    2009-01-01

    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) the numbers of tsetse attracted to the odour source and (2) the proportion of flies that landed on a black target (1×1 m). In addition responses to monitor lizard (Varanus niloticus) were assessed in Kenya. The effects of all four odours on the proportion of tsetse that entered a biconical trap were also determined. Sources of natural host odour were produced by placing live hosts in a tent or metal hut (volumes?16 m3) from which the air was exhausted at ?2000 L/min. Odours from cattle, pigs and humans had no significant effect on attraction of G. f. fuscipes but lizard odour doubled the catch (P<0.05). Similarly, mammalian odours had no significant effect on landing or trap entry whereas lizard odour increased these responses significantly: landing responses increased significantly by 22% for males and 10% for females; the increase in trap efficiency was relatively slight (5–10%) and not always significant. For G. f. quanzensis, only pig odour had a consistent effect, doubling the catch of females attracted to the source and increasing the landing response for females by ?15%. Dispensing CO2 at doses equivalent to natural hosts suggested that the response of G. f. fuscipes to lizard odour was not due to CO2. For G. f. quanzensis, pig odour and CO2 attracted similar numbers of tsetse, but CO2 had no material effect on the landing response. The results suggest that identifying kairomones present in lizard odour for G. f. fuscipes and pig odour for G. f. quanzensis may improve the performance of targets for controlling these species. PMID:19434232

  5. Control of human African trypanosomiasis in the Quiçama focus, Angola.

    PubMed Central

    Ruiz, José Antonio; Simarro, Pere P.; Josenando, Teofilo

    2002-01-01

    OBJECTIVE: To update the epidemiological status of human African trypanosomiasis (HAT), also known as sleeping sickness, in the Quiçama focus, province of Bengo, Angola, and to establish a HAT control programme. METHODS: In 1997, 8796 people (the population of 31 villages) were serologically screened for Trypanosoma brucei gambiense, the causative agent of HAT. In 1998 and 1999, surveys were carried out in villages where HAT cases had been identified in 1997. Individuals were screened using the card agglutination trypanosomiasis test (CATT), and then examined for the presence of the parasite. CATT- positive individuals in whom the presence of the parasite could not be confirmed were further tested with the CATT using serum dilutions, and those with a positive antibody end titre of 1-in-4 or above were followed-up. Patients with < or =10 white cells/micro l and no trypanosomes in their cerebrospinal fluid (CSF) were classified as being in the first stage of the disease. Vector control was not considered necessary or feasible. FINDINGS: The main transmission areas were on the Kwanza riverbanks, where 5042 inhabitants live. In 1997, the HAT prevalence was 1.97%, but this decreased to 0.55% in 1998 and to 0.33% in 1999. The relapse rate was 3% in patients treated with pentamidine and 3.5% in patients treated with melarsoprol. In patients treated with pentamidine, there was no difference in the relapse rate for patients with initial CSF white cell counts of 0-5 cells/ micro l or 6-10 cells/micro l. The overall mortality rate was 0.6% and the rate of reactive arsenical encephalopathy among the melarsoprol-treated patients was 1.7%. CONCLUSION: The epidemiological status of the disease was updated and the transmission areas were defined. The control methods implemented allowed the disease prevalence to be reduced. PMID:12378293

  6. Genome Sequence of the Tsetse Fly (Glossina morsitans): Vector of African Trypanosomiasis

    PubMed Central

    2014-01-01

    Tsetse flies are the sole vectors of human African trypanosomiasis throughout sub-Saharan Africa. Both sexes of adult tsetse feed exclusively on blood and contribute to disease transmission. Notable differences between tsetse and other disease vectors include obligate microbial symbioses, viviparous reproduction, and lactation. Here, we describe the sequence and annotation of the 366-megabase Glossina morsitans morsitans genome. Analysis of the genome and the 12,308 predicted protein–encoding genes led to multiple discoveries, including chromosomal integrations of bacterial (Wolbachia) genome sequences, a family of lactation-specific proteins, reduced complement of host pathogen recognition proteins, and reduced olfaction/chemosensory associated genes. These genome data provide a foundation for research into trypanosomiasis prevention and yield important insights with broad implications for multiple aspects of tsetse biology. PMID:24763584

  7. Genome sequence of the tsetse fly (Glossina morsitans): vector of African trypanosomiasis.

    PubMed

    2014-04-25

    Tsetse flies are the sole vectors of human African trypanosomiasis throughout sub-Saharan Africa. Both sexes of adult tsetse feed exclusively on blood and contribute to disease transmission. Notable differences between tsetse and other disease vectors include obligate microbial symbioses, viviparous reproduction, and lactation. Here, we describe the sequence and annotation of the 366-megabase Glossina morsitans morsitans genome. Analysis of the genome and the 12,308 predicted protein-encoding genes led to multiple discoveries, including chromosomal integrations of bacterial (Wolbachia) genome sequences, a family of lactation-specific proteins, reduced complement of host pathogen recognition proteins, and reduced olfaction/chemosensory associated genes. These genome data provide a foundation for research into trypanosomiasis prevention and yield important insights with broad implications for multiple aspects of tsetse biology. PMID:24763584

  8. Control and surveillance of African trypanosomiasis. Report of a WHO Expert Committee.

    PubMed

    1998-01-01

    Current estimates indicate that 60 million people are at risk of infection with human African trypanosomiasis or sleeping sickness, with about 300,000 new cases each year. However, less than 4 million people are under surveillance and only 10% of new cases are diagnosed and treated. This report of a WHO Expert Committee reviews current epidemiological information on African trypanosomiasis and its vectors, and evaluates recent advances in drug treatment and the development of tools for the control and surveillance of the disease. The report provides examples of treatment schedules, vector control operations, indicators for monitoring control and surveillance activities and sample calculations for analysing the cost-effectiveness of different strategies, as well as details of methods for cryopreservation of trypanosome-infected blood samples and a description of traps and screens for the control of the insect vector, Glossina. Although primarily addressed to health policy-makers in countries endemic for sleeping sickness, this report will also be a useful reference source for health care staff at all levels, including physicians, nurses, auxiliary staff and students, as well as those engaged in research on the disease. PMID:10070249

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

    PubMed Central

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

    1963-01-01

    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. PMID:13928678

  10. Recent advances in research and control of malaria, leishmaniasis, trypanosomiasis and schistosomiasis.

    PubMed

    Croft, S L; Vivas, L; Brooker, S

    2003-07-01

    In the Eastern Mediterranean Region of the World Health Organization (WHO), malaria, schistosomiasis, leishmaniasis and trypanosomiasis are the parasitic diseases of major importance. Our review focuses on recent advances in the control and treatment of these diseases with particular reference to diagnosis, chemotherapy, vaccines, vector and environmental control. The Roll Back Malaria Programme, for example, emphasizes the use of insecticide treated bednets in Africa and targets a 30-fold increase in treated bednet use by 2007. Increasing risk factors for leishmaniasis include urbanization, extended agricultural projects and civil unrest and the increase in patients with Leishmania infantum and HIV co-infection in the Region may signal a new threat. In the past 20 years, human African trypanosomiasis has resurged in sub-Saharan Africa; within the Region it has become more common in the southern Sudan where anthroponotic and zoonotic sub-species infections overlap. Schistosomiasis in the Region is caused by either Schistosoma haematobium or S. mansoni and large-scale control efforts include providing regular treatment to at-risk groups and supporting drug delivery through schools. PMID:15748049

  11. The current epidemiology and control of trypanosomiasis and other zoonoses in Tanzania.

    PubMed

    Kilonzo, B S; Komba, E K

    1993-01-01

    The epidemiology and control strategies of African trypanosomiasis, plague, rabies, brucellosis, anthrax and hydatidosis, the most important and well documented zoonotic diseases in Tanzania, have been described. Bovine tuberculosis, tetanus, taeniosis, trichinosis and tungosis are also endemic in some parts of the country but records of their incidences are not available. Initial outbreaks of trypanosomiasis in Tanzania were caused by Trypanosoma gambiense which originated from West Africa and reached Tanzania via Zaire around 1902. T. rhodesiense which is currently responsible for human trypanosomiasis in Tanzania was introduced from Mozambique around 1910 and quickly spread to many parts of the country. The disease is currently prevalent in the western, north and northwestern parts, the southern highlands and southern regions. Over 6000 cases have reported since 1979. Control strategies against sleeping sickness in Tanzania include chemical control of vectors, treatment of patients with trypanocides and avoidance of humantsetse contact. Plague is mostly endemic in central, northern and north-eastern Tanzania. A total of 8161 cases with 1885 deaths have been recorded since 1890. The disease is currently prevalent in Lushoto district where outbreaks have been experienced since 1980, and in Singida district where it has been endemic since 1918. Integrated control measures are currently applied and were possibly responsible for the 1989 decline of outbreaks in the area. Financial constraints which led to deterioration of control activities from July 1989 probably accounted for the severe outbreaks in 1990/91 which spread to other parts of the country. Rabies is endemic country-wide except in Mtwara, Lindi and Zanzibar. Domestic dogs are the principal transmitters and prompt vaccination and destruction of unvaccinated stray dogs are the main control measures. Brucellosis is widely endemic in livestock and potentially so in humans. Destruction of infected animals, immunisation of susceptible ones, proper boiling of milk and its products and chemotherapy are the currently applied control measures against the disease. Anthrax and hydatidosis are sparsely endemic in the country, and they are mostly controlled by appropriate meat inspection and consequent condemnation and proper disposal of the affected meat. Vaccination and treatment of animals are also effective against anthrax. PMID:8261496

  12. Interactions between tsetse and trypanosomes with implications for the control of trypanosomiasis

    Microsoft Academic Search

    Serap Aksoy; Wendy C. Gibson; Michael J. Lehane

    2003-01-01

    Tsetse flies (Diptera: Glossinidae) are vectors of several species of pathogenic trypanosomes in tropical Africa. Human African trypanosomiasis (HAT) is a zoonosis caused by Trypanosoma brucei rhodesiense in East Africa and T. b. gambiense in West and Central Africa. About 100 000 new cases are reported per year, with many more probably remaining undetected. Sixty million people living in 36

  13. Trypanosomiasis and Tsetse Control with Insecticidal Pour-ons— Fact and Fiction?

    Microsoft Academic Search

    M. Baylis; P. Stevenson

    1998-01-01

    Insecticidal pour-ons that are applied directly to cattle have been promoted widely in the last decade as a new means of controlling tsetse flies in Africa. Tsetse attracted to treated cattle get a lethal dose of insecticide and die. Following a large trial in Kenya, Matthew Baylis and Peter Stevenson argue here that the reduction in trypanosomiasis incidence caused by

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

    Microsoft Academic Search

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

    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

  15. Evaluation of a novel method for controlling bovine trypanosomiasis 

    E-print Network

    Brownlow, Andrew C.

    2007-11-27

    The problem of controlling tsetse flies in Africa is an old one. The tsetse fly transmits the trypanosome parasites which cause sleeping sickness in humans and disease in cattle. Because cattle are a favoured food source ...

  16. Potential demand for a mixed public-private animal health input: evaluation of a pour-on insecticide for controlling tsetse-transmitted trypanosomiasis in Ethiopia

    Microsoft Academic Search

    Brent M. Swallow; Woudyalew Mulatu; Stephen G. A. Leak

    1995-01-01

    The new pour-on insecticides that can be used to control tsetse-transmitted trypanosomiasis confer benefits to the owners of the cattle given treatments and other people keeping cattle in areas affected by the control. A study was conducted in southwest Ethiopia to assess farmers' perceptions of the public and private benefits of the pour-on and identify the household-level factors affecting its

  17. African Trypanosomiasis Gambiense, Italy

    PubMed Central

    Beltrame, Anna; Monteiro, Geraldo; Arzese, Alessandra; Marocco, Stefania; Rorato, Giada; Anselmi, Mariella; Viale, Pierluigi

    2005-01-01

    African trypanosomiasis caused by Trypanosoma brucei gambiense has not been reported in Italy. We report 2 cases diagnosed in the summer of 2004. Theses cases suggest an increased risk for expatriates working in trypanosomiasis-endemic countries. Travel medicine clinics should be increasingly aware of this potentially fatal disease. PMID:16318728

  18. [Human African trypanosomiasis].

    PubMed

    Dumas, M; Bouteille, B

    1996-01-01

    Human African trypanosomiasis (HAT) is caused by infestation with a flagellate protozoan, the trypanosome which is inoculated by the bite of the tsetse fly Glossina. The particular ecological conditions of parasites and vectors are such that the disease is only found in the intertropical regions of Africa. Although there are many species of trypanosomes, only two, belonging to the brucei group are likely to lead to HAT. These two species are quite similar morphologically but have different pathogenicity. Trypanosoma brucei gambiense found in West and Central Africa leads to a chronic form of the disease or sleeping sickness. T. b. rhodesiense leads to a more virulent and acute condition, although for each species of trypanosome there are strains of different virulence, which account, at least in part, for the interindividual variability in the clinical course. Immediately after penetration into the human organism, the trypanosome multiplies at the point of inoculation, producing a local inflammatory reaction. It then invades the whole organism, and the central nervous system (CNS). The involvement of the CNS leads to an irreversible demyelinating process ending by death without treatment. Apart from the initial stages, it is not easy to determine the phase of the disease that the patient is presenting. The parasite can escape the host immune response by varying the surface glycoprotein coat. Variable surface glycoproteins (VSG) are strongly antigenic and lead to great antibody response with immune lysis. But, some heterologous antigenic variants can survive to repopulate blood and other tissues. This mechanism of antigenic variation is under parasite genetic control. The trypanosome can release numerous pathogenic substances which cause alterations in cytokine/prostaglandin network. A 41-46 kDa molecule termed trypanosome-released lymphocyte trigerring factor may selectively activate CD8+ T cells to produce interferon-gamma which then activates macrophages but also promotes parasite growth. Activated macrophages release tumor necrosis factor alpha and nitric oxide (NO) which are trypanostatic static and other cytokines and prostanglandins. These macrophage relased substances enhance the immunosuppression and alter the blood brain barrier (BBB). So, trypanosomes and inflammatory cells can invade the CNS leading to a progressive meningoencephalitis with typical perivascular cuffings which explain neurological disorders and neuroendocrine alterations. The inflammatory cells (lymphocytes, astrocytes, glial cells) produce cytokines, NO and other mediators and enhance the CNS immunopathological process. The peri-ventricular regions, the tuberoinfundibula and thalamic-hypothalamic regions, are particulary involved. These disturbances lead to a progressively complete disruption of the normal sleep-waking cycle. Antibodies anti-CNS components (galactocerebrosides, neurofilaments, tryptophane) are also described in sera and cerebrospinal fluid (CSF) of HAT patients. Their presence may be due to cross reactions with comon epitopes between host and trypanosomes which can lead to a self-propagating autoimmune reaction, which accounts for the marked demyelination found in the late stage of the disease. The diagnosis of CNS involvement in not easy to establish in the early neurological phase in the absence of neurological signs and in absence of great chnages in CSF. This is an important problem because it is the basis to apply existing available drugs. pentamidine and suramin are effective only in early stages of the disease when CNS is not invaded. Melarsoprol is effective in all-stages: this is the drug of choice when CNS is involved. Unfortunaley, melarsoprol is toxic and, in 5% of treated patients, this drug can lead to arsenical encephalopathy which is often fatal. In the continuing search for new antitrypanosonal drugs, biochemical peculiarities of the trypanosome are used as drug garget, especially glycolysis, trypanothione, sensibil PMID:8952890

  19. The impact of insecticide-resistance on control of vectors and vector-borne diseases

    PubMed Central

    Busvine, J. R.; Pal, R.

    1969-01-01

    A questionnaire inquiring into the nature of schemes for the insecticidal control of disease vectors, the development of resistance in these vectors, and the effect of any such resistance on their control and on the extent of disease was sent to more than 100 health authorities throughout the world. The replies to the questionnaire are summarized in this paper. Until recently, the use of insecticides in public health has been largely based on three organochlorine compounds—DDT, HCH and dieldrin. However, in some countries resistance to these has now severely affected control both of many insect species and of the diseases they transmit (e.g., malaria, yellow fever, filariasis, typhus, plague). Certain other public health problems (onchocerciasis, Chagas' disease, trypanosomiasis, leishmaniasis) have not so far been greatly affected by resistance, but it is difficult to be sure of the continued reliability of the organochlorines. Research in the past 5 years, much of it sponsored by WHO, has shown the value of various organophosphorus and carbamate insecticides as replacements for the organochlorines, although resistance to them, too, can occur. Attention must therefore be focused on all facets of the use of these newer compounds and particular scrutiny made of possible instances of resistance to them. PMID:5307234

  20. Ecology and vector control

    PubMed Central

    Davis, D. H. S.

    1963-01-01

    One of the primary functions of ecological work is to conduct surveys of those species of vertebrates and/or invertebrates that are involved directly or indirectly in vector-borne diseases of man. The aim in southern Africa has been to contribute to a stable nomenclature at the species level, to determine the range of each species and to make an attempt to single out key environmental limiting factors. Once the taxonomic status and range of the species have been established with some degree of certainty, species may be studied in relation to the distribution and prevalence of any particular disease in order to provide the basis for control. The bio-geographical approach that has been adopted arose when the geographical distribution of human plague derived from wild-rodent sources came to be compared with the distribution of the small mammals and their respective fleas. This threw much light on the factors concerned in the limitation and persistence of plague. These comparative studies were facilitated by plotting the distribution data on grid maps. ImagesFIG. 1FIG. 1(continued) PMID:20604161

  1. American trypanosomiasis (Chagas disease).

    PubMed

    Rassi, Anis; Rassi, Anis; Marcondes de Rezende, Joffre

    2012-06-01

    Chagas disease, also known as American trypanosomiasis, is a chronic infection caused by Trypanosoma cruzi, a protozoan parasite. It is transmitted to human beings mainly through the feces of infected triatomine bugs. The disease affects an estimated 8 to 10 million people in the Americas, putting them at risk of developing life-threatening cardiac and gastrointestinal complications. This article provides a brief update on the epidemiology, clinical manifestations, diagnosis, and treatment of Chagas disease. PMID:22632639

  2. Effects of Climate, Human Population and Socioeconomic Changes on Tsetse-transmitted Trypanosomiasis to 2050

    Microsoft Academic Search

    J. J. McDermott; P. M. Kristjanson; R. L. Kruska; R. S. Reid; T. P. Robinson; P. G. Coleman; P. G. Jones; P. K. Thornton

    This chapter explores the impacts of climate change, human population growth and expected disease control activities on tsetse\\u000a distribution and trypanosomiasis risk in five agro-ecological environments in sub-Saharan Africa to 2050. These changes will\\u000a tend to contract areas under trypanosomiasis risk continent-wide; however, this trend will not be uniform. The greatest decrease\\u000a in the impacts of animal trypanosomiasis will occur

  3. Progress in malaria vector control*

    PubMed Central

    Pant, C. P.; Rishikesh, N.; Bang, Y. H.; Smith, A.

    1981-01-01

    Malaria control, except in tropical Africa, will probably continue to be based to a large extent on the use of insecticides for many years. However, the development of resistance to insecticides in the vectors has caused serious difficulties and it is necessary to change the strategy of insecticide use to maximize their efficacy. A thorough knowledge of the ecology and behaviour of each vector species is required before the control strategy can be adapted to different epidemiological situations. The behavioural differences between sibling species have been recognized for several years, but study of this problem has recently been simplified by improved means of identification that involve chromosomal banding patterns and electrophoretic analysis. Behavioural differences have also been associated with certain chromosomal rearrangements. New records of insecticide resistance among anophelines continue to appear and the impact of this on antimalaria operations has been seriously felt in Central America (multi-resistance in Anopheles albimanus), Turkey (A. sacharovi), India and several Asian countries (A. culicifacies and A. stephensi), and some other countries. Work continues on the screening and testing of newer insecticides that can be used as alternatives, but DDT, malathion, temephos, fenitrothion, and propoxur continue to be used as the main insecticides in many malaria control projects. The search for simpler and innovative approaches to insecticide application also continues. Biological control of vectors is receiving increased attention, as it could become an important component of integrated vector control strategies, and most progress has been made with the spore-forming bacterium, serotype H-14 of Bacillus thuringiensis. Larvivorous fish such as Gambusia spp. and Poecilia spp. continue to be used in some programmes. Application of environmental management measures, such as source reduction, source elimination, flushing of drainage and irrigation channels, and intermittent irrigation have been re-examined and currently a great deal of interest is being shown in these approaches. There has been limited interest in the genetic control of mosquitos and the phenomenon of refractoriness in some strains of the disease vectors, with the idea of replacing the vector species with the refractory strain. More research is needed before this approach can become a practical tool. It is apparent that in future a more integrated approach will have to be used for vector control within the context of antimalaria programmes. Training of staff, research, and cooperation at all levels will be an essential requirement for this approach. PMID:6976842

  4. Emergence and Prevalence of Human Vector-Borne Diseases in Sink Vector Populations

    E-print Network

    Paris-Sud XI, Université de

    duration of infection; malaria and the American and African trypanosomiasis. Vector-related parameters were and African trypanosomiasis [3]. All these diseases have severe impacts on many tropical and subtropical

  5. Human African trypanosomiasis.

    PubMed

    Brun, Reto; Blum, Johannes

    2012-06-01

    Human African trypanosomiasis (sleeping sickness) is caused by the unicellular parasite Trypanosoma brucei and transmitted by tsetse flies. It occurs exclusively in sub-Saharan Africa, usually in rural areas affected by civil conflicts and neglected health systems. Reported cases are fewer than 10,000/year, which classifies it as one of the most neglected tropical diseases. Because sleeping sickness is fatal if not treated, it has to be included in the differential diagnosis of every febrile traveler returning from a game park in East Africa. Elimination of the disease is considered feasible provided better tools for diagnosis and treatment can be made available. PMID:22632638

  6. Vaccination against trypanosomiasis

    PubMed Central

    La Greca, Florencia

    2011-01-01

    To date, human African trypanosomiasis (HAT) still threatens millions of people throughout sub-Sahara Africa, and new approaches to disease prevention and treatment remain a priority. It is commonly accepted that HAT is fatal unless treatment is provided. However, despite the well-described general symptoms of disease progression during distinct stages of the infection, leading to encephalitic complications, coma and death, a substantial body of evidence has been reported suggesting that natural acquired immunity could occur. Hence, if under favorable conditions natural infections can lead to correct immune activation and immune protection against HAT, the development of an effective anti-HAT vaccine should remain a central goal in the fight against this disease.
    In this review, we will (1) discuss the vaccine candidates that have been proposed over the past years, (2) highlight the main obstacles that an efficient anti-trypanosomiasis vaccine needs to overcome and (3) critically reflect on the validity of the widely used murine model for HAT. PMID:22205439

  7. Impacts of trypanosomiasis on African agriculture

    Microsoft Academic Search

    Brent M. Swallow

    African animal trypanosomiasis constrains agricultural production in areas of Africa that hold the continent's greatest potential for expanded agricultural production. Compared to animals kept in trypanosomiasis free areas, animals kept in areas of moderate risk of trypanosomiasis have lower calving rates, lower milk yields, higher rates of calf mortality, and require more frequent treatment with preventive and curative doses of

  8. Socio-Economic and Cultural Determinants of Human African Trypanosomiasis at the Kenya – Uganda Transboundary

    PubMed Central

    Rutto, Jane Jemeli; Osano, Odipo; Thuranira, Elias Gitonga; Kurgat, Richard Kiptum; Odenyo, Victor Agab Omondi

    2013-01-01

    Background Kenya and Uganda have reported different Human African Trypanosomiasis incidences in the past more than three decades, with the latter recording more cases. This cross-sectional study assessed the demographic characteristics, tsetse and trypanosomiasis control practices, socio-economic and cultural risk factors influencing Trypanosoma brucei rhodesiense (T.b.r.) infection in Teso and Busia Districts, Western Kenya and Tororo and Busia Districts, Southeast Uganda. A conceptual framework was postulated to explain interactions of various socio-economic, cultural and tsetse control factors that predispose individuals and populations to HAT. Methods A cross-sectional household survey was conducted between April and October 2008. Four administrative districts reporting T.b.r and lying adjacent to each other at the international boundary of Kenya and Uganda were purposely selected. Household data collection was carried out in two villages that had experienced HAT and one other village that had no reported HAT case from 1977 to 2008 in each district. A structured questionnaire was administered to 384 randomly selected household heads or their representatives in each country. The percent of respondents giving a specific answer was reported. Secondary data was also obtained on socio-economic and political issues in both countries. Results Inadequate knowledge on the disease cycle and intervention measures contributed considerable barriers to HAT, and more so in Uganda than in Kenya. Gender-associated socio-cultural practices greatly predisposed individuals to HAT. Pesticides-based crop husbandry in the 1970's reportedly reduced vector population while vegetation of coffee and banana's and livestock husbandry directly increased occurrence of HAT. Livestock husbandry practices in the villages were strong predictors of HAT incidence. The residents in Kenya (6.7%) applied chemoprophylaxis and chemotherapeutic controls against trypanosomiasis to a larger extent than Uganda (2.1%). Conclusion Knowledge on tsetse and its control methods, culture, farming practice, demographic and socio-economic variables explained occurrence of HAT better than landscape features. PMID:23638206

  9. Problems of diagnosis of trypanosomiasis*

    PubMed Central

    Weinman, David

    1963-01-01

    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. PMID:13999624

  10. Parameter estimation of vector controlled induction machine 

    E-print Network

    Rahman, Tahmid Ur

    2002-01-01

    and operation at low speed, indirect vector control is becoming popular. But as the rotor time constant varies the detuning of the control system occurs. Without exact rotor time constant the slip frequency calculation becomes inexact. In this thesis most...

  11. African bovine trypanosomiasis: the problem of drug resistance

    Microsoft Academic Search

    Stanny Geerts; Peter H Holmes; Mark C Eisler; Oumar Diall

    2001-01-01

    The three trypanocides used to control tsetse-transmitted trypanosomiasis in domestic animals in Africa have been in use for over 40 years and, not surprisingly, resistance of trypanosomes to these drugs has emerged. Because of the relatively limited market in Africa and the high costs of developing and licensing new drugs, international pharmaceutical companies have shown little interest in the development

  12. Understanding bovine trypanosomiasis and trypanotolerance: the promise of functional genomics

    Microsoft Academic Search

    Emmeline W. Hill; Grace M. O’Gorman; Morris Agaba; John P. Gibson; Olivier Hanotte; Stephen J. Kemp; Jan Naessens; Paul M. Coussens; David E. MacHugh

    2005-01-01

    African bovine trypanosomiasis, caused by the protozoan parasite Trypanosoma congolense, is endemic throughout sub-Saharan Africa and is a major constraint on livestock production. A promising approach to disease control is to understand and exploit naturally evolved trypanotolerance. We describe the first attempt to investigate the transcriptional response of susceptible Boran (Bos indicus) cattle to trypanosome infection via a functional genomics

  13. Chagas disease (American trypanosomiasis) in Mexico: an update.

    PubMed

    Carabarin-Lima, Alejandro; González-Vázquez, María Cristina; Rodríguez-Morales, Olivia; Baylón-Pacheco, Lidia; Rosales-Encina, José Luis; Reyes-López, Pedro Antonio; Arce-Fonseca, Minerva

    2013-08-01

    Chagas disease is a parasitic infection caused by the protozoan Trypanosoma cruzi, a flagellated organism that is transmitted mainly to humans through the infected feces of triatomine kissing bugs (vector transmission in endemic areas) or by transfusion of infected blood, donations of infected organ, or transmission from an infected mother to her child at birth. Chagas disease was first described in 1909 by the Brazilian physician Carlos Chagas, and due to the parasite's distribution throughout North, Central and South America, the disease is commonly known as American trypanosomiasis. However, this disease is now present in non-endemic countries such as Canada, the United States of America, and several countries in Europe (principally Spain). Moreover, Chagas disease was recently designated by the World Health Organization as one of the main neglected tropical diseases. The aim of this review is to summarize the research efforts recently described in studies conducted in Mexico on Chagas disease. In this country, there are no existing vector control programs. In addition, there is no consensus on the diagnostic methods for acute and chronic Chagas disease in maternity wards and blood banks, and trypanocidal therapy is not administered to chronic patients. The actual prevalence of the disease is unknown because no official reporting of cases is performed. Therefore, the number of people infected by different routes of transmission (vector, congenital, blood transfusion, organ transplantation, or oral) is unknown. We believe that by promoting education about Chagas disease in schools starting at the basic elementary level and including reinforcement at higher education levels will ensure that the Mexican population would be aware of this health problem and that the control measures adopted will have more acceptance and success. We hope that this review sensitizes the relevant authorities and that the appropriate measures to reduce the risk of infection by T. cruzi are undertaken to provide the Mexican people a better quality of life. PMID:23643518

  14. Vector control activities. Fiscal year, 1982

    SciTech Connect

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

    1983-06-01

    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.

  15. Glossina fuscipes populations provide insights for Human African Trypanosomiasis transmission in Uganda

    PubMed Central

    Aksoy, Serap; Caccone, Adalgisa; Galvani, Alison P.; Okedi, Loyce M.

    2013-01-01

    Uganda has both forms of human African trypanosomiasis (HAT): the chronic gambiense disease in the northwest and the acute rhodesiense disease in the south. The recent spread of rhodesiense into central Uganda has raised concerns given the different control strategies the two diseases require. We present knowledge on the population genetics of the major vector species Glossina fuscipes fuscipes in Uganda with a focus on population structure, measures of gene flow between populations, and the occurrence of polyandry. The microbiome composition and diversity is discussed, focusing on their potential role on trypanosome infection outcomes. We discuss the implications of these findings for large-scale tsetse control programs, including suppression or eradication, being undertaken in Uganda and potential future genetic applications. PMID:23845311

  16. Mathematical models of human african trypanosomiasis epidemiology.

    PubMed

    Rock, Kat S; Stone, Chris M; Hastings, Ian M; Keeling, Matt J; Torr, Steve J; Chitnis, Nakul

    2015-03-01

    Human African trypanosomiasis (HAT), commonly called sleeping sickness, is caused by Trypanosoma spp. and transmitted by tsetse flies (Glossina spp.). HAT is usually fatal if untreated and transmission occurs in foci across sub-Saharan Africa. Mathematical modelling of HAT began in the 1980s with extensions of the Ross-Macdonald malaria model and has since consisted, with a few exceptions, of similar deterministic compartmental models. These models have captured the main features of HAT epidemiology and provided insight on the effectiveness of the two main control interventions (treatment of humans and tsetse fly control) in eliminating transmission. However, most existing models have overestimated prevalence of infection and ignored transient dynamics. There is a need for properly validated models, evolving with improved data collection, that can provide quantitative predictions to help guide control and elimination strategies for HAT. PMID:25765194

  17. Proteomics: a new way to improve human African trypanosomiasis diagnosis?

    PubMed

    Holzmuller, Philippe; Grébaut, Pascal; Semballa, Silla; Gonzatti, Mary Isabel; Geiger, Anne

    2013-06-01

    African trypanosomiases, including the human disease referred to as 'sleeping sickness' and the animal diseases such as nagana, surra and dourine, are neglected vector-borne diseases that after years of research still need improved diagnosis and chemotherapy. Advances in proteomics offer new tools to define biomarkers, whose expression may reflect host-parasite interactions occurring during the infection. In this review, the authors first describe the current diagnostic tools used to detect a trypanosome infection during field surveys, and then discuss their interests, limits and further evolutions. The authors also report on the contribution of molecular diagnostics, and the recent advances and developments that make it suitable for fieldwork. The authors then explore the recent uses of proteomics technology to define host and parasite biomarkers that allow detection of the infection, the power and constraints of the technology. The authors conclude by discussing the urgent need to use the biomarkers discovered in order to develop tools to improve trypanosomiasis control in the near future. PMID:23777218

  18. Constrained motion control using vector potential fields

    Microsoft Academic Search

    Samer A. Masoud; Ahmad A. Masoud

    2000-01-01

    This paper discusses the generation of a control signalthat would instruct the actuators of a robotics manipulator to drivemotion along a safe and well-behaved path to a desired target. Theproposed concept of navigation control along with the tools necessaryfor its construction achieve this goal. The most significant toolis the artificial vector potential field which shows a better ability tosteer motion

  19. Vector control operations in the African context.

    PubMed

    Zahar, A R

    1984-01-01

    In order to define the scope of vector control as a component of malaria control in the WHO African Region, examples of recent experiences with different vector control methods in this region are reviewed. Residual house spraying applied alone or in combination with mass drug administration has failed to interrupt malaria transmission in savanna areas for several technical and administrative reasons. Nevertheless, there is evidence that residual house spraying has led to an improvement in general health. However, the existence of DDT and dieldrin/HCH and lately malathion resistance in the Sudan in Anopheles gambiae s.l. would militate against the use of residual house spraying as a main tool for long-term malaria control. It should therefore be used only to reduce malaria prevalence to an acceptable level until integrated control methods can be developed and become operational.Experience with larval control, space spraying, and biological control of vectors is also reviewed, and the value of self-help methods of reducing man-vector contact under African conditions is examined. All these methods need to be more thoroughly assessed. Several proposals are made for applied field research. PMID:6397279

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

    Microsoft Academic Search

    José A Castro; María Montalto deMecca; Laura C Bartel

    2006-01-01

    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%

  1. Thrust vector control using electric actuation

    Microsoft Academic Search

    Robert T. Bechtel; David K. Hall

    1995-01-01

    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

  2. Electromechanical actuation for thrust vector control applications

    Microsoft Academic Search

    Mary Ellen Roth

    1990-01-01

    At present, actuation systems for the Thrust Vector Control (TVC) for launch vehicles are hydraulic systems. The Advanced Launch System (ALS), a joint initiative between NASA and the Air Force, is a launch vehicle that is designed to be cost effective, highly reliable and operationally efficient with a goal of reducing the cost per pound to orbit. As part of

  3. CONTRIBUTIONS OF INVERTEBRATE PATHOLOGY TO VECTOR CONTROL

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Control of the invertebrate host is an integral part of any integrated program to prevent the spread of vector borne diseases of man and animals. This includes important mosquito borne arboviruses such as yellow fever, dengue and the various types of encephalitis including West Nile Virus, St. Loui...

  4. Substituted 2Phenylimidazopyridines: A New Class of Drug Leads for Human African Trypanosomiasis

    E-print Network

    Gelb, Michael

    Substituted 2Phenylimidazopyridines: A New Class of Drug Leads for Human African Trypanosomiasis brucei, the causative agent of human African trypanosomiasis, led to the identification of substituted 2 trypanosomiasis. INTRODUCTION Two protozoan agents cause human African trypanosomiasis (HAT): Trypanosoma brucei

  5. Thrust Vectoring Flow Control Using Plasma Actuators

    NASA Astrophysics Data System (ADS)

    Jacob, Jamey; Bolitho, Michael

    2007-11-01

    Thrust vectoring flow control is demonstrated using plasma synthetic jet actuators (PSJA). The PSJA is a geometric variant of a plasma actuator, consisting of a symmetric electrode array that results in a circular region of dielectric barrier discharge plasma. Quiescent flow PIV measurements of the PSJA reveal that the flowfield on actuation resembles that of a zero-mass flux or synthetic jet that is useful for flow control, particularly separation reduction. Like synthetic jets, unsteady pulsed actuator operation results in formation of multiple vortex rings. The output jet momentum is found to be affected by the power input, actuator dimension and pulsing frequency. While increasing the input power increases the maximum jet velocity, an optimum range of pulsing frequencies and actuator dimensions are observed to exist in order to maximize jet momentum. By asymmetrically varying the plasma input parameters, such as frequency, amplitude and duty cycle, it is possible to control the jet angle. Vectoring using high frequency pusling akin to synthetic jets is more effective than vectoring by modifying steady control inputs and differences in control effectiveness are due primarily to the time scales associated with the vortex formation.

  6. Travelers' Health: Trypanosomiasis, American (Chagas Disease)

    MedlinePLUS

    ... gov . Home Destinations Travel Notices Find a Clinic Yellow Fever Vaccinations Clinics FAQ Disease Directory Information Centers For Travelers Common Travel Health Topics Adopting a Child from Another Country Adventure ... Yellow Book Contents Chapter 3 (78) Trypanosomiasis, American (Chagas ...

  7. Using species distribution models to optimize vector control in the framework of the tsetse eradication campaign in Senegal

    PubMed Central

    Dicko, Ahmadou H.; Lancelot, Renaud; Seck, Momar T.; Guerrini, Laure; Sall, Baba; Lo, Mbargou; Vreysen, Marc J. B.; Lefrançois, Thierry; Fonta, William M.; Peck, Steven L.; Bouyer, Jérémy

    2014-01-01

    Tsetse flies are vectors of human and animal trypanosomoses in sub-Saharan Africa and are the target of the Pan African Tsetse and Trypanosomiasis Eradication Campaign (PATTEC). Glossina palpalis gambiensis (Diptera: Glossinidae) is a riverine species that is still present as an isolated metapopulation in the Niayes area of Senegal. It is targeted by a national eradication campaign combining a population reduction phase based on insecticide-treated targets (ITTs) and cattle and an eradication phase based on the sterile insect technique. In this study, we used species distribution models to optimize control operations. We compared the probability of the presence of G. p. gambiensis and habitat suitability using a regularized logistic regression and Maxent, respectively. Both models performed well, with an area under the curve of 0.89 and 0.92, respectively. Only the Maxent model predicted an expert-based classification of landscapes correctly. Maxent predictions were therefore used throughout the eradication campaign in the Niayes to make control operations more efficient in terms of deployment of ITTs, release density of sterile males, and location of monitoring traps used to assess program progress. We discuss how the models’ results informed about the particular ecology of tsetse in the target area. Maxent predictions allowed optimizing efficiency and cost within our project, and might be useful for other tsetse control campaigns in the framework of the PATTEC and, more generally, other vector or insect pest control programs. PMID:24982143

  8. Using species distribution models to optimize vector control in the framework of the tsetse eradication campaign in Senegal.

    PubMed

    Dicko, Ahmadou H; Lancelot, Renaud; Seck, Momar T; Guerrini, Laure; Sall, Baba; Lo, Mbargou; Vreysen, Marc J B; Lefrançois, Thierry; Fonta, William M; Peck, Steven L; Bouyer, Jérémy

    2014-07-15

    Tsetse flies are vectors of human and animal trypanosomoses in sub-Saharan Africa and are the target of the Pan African Tsetse and Trypanosomiasis Eradication Campaign (PATTEC). Glossina palpalis gambiensis (Diptera: Glossinidae) is a riverine species that is still present as an isolated metapopulation in the Niayes area of Senegal. It is targeted by a national eradication campaign combining a population reduction phase based on insecticide-treated targets (ITTs) and cattle and an eradication phase based on the sterile insect technique. In this study, we used species distribution models to optimize control operations. We compared the probability of the presence of G. p. gambiensis and habitat suitability using a regularized logistic regression and Maxent, respectively. Both models performed well, with an area under the curve of 0.89 and 0.92, respectively. Only the Maxent model predicted an expert-based classification of landscapes correctly. Maxent predictions were therefore used throughout the eradication campaign in the Niayes to make control operations more efficient in terms of deployment of ITTs, release density of sterile males, and location of monitoring traps used to assess program progress. We discuss how the models' results informed about the particular ecology of tsetse in the target area. Maxent predictions allowed optimizing efficiency and cost within our project, and might be useful for other tsetse control campaigns in the framework of the PATTEC and, more generally, other vector or insect pest control programs. PMID:24982143

  9. Electromechanical actuator for thrust vector control

    NASA Astrophysics Data System (ADS)

    Zubkow, Zygmunt

    Attention is given to the development and testing of electromechanical actuator (EMA) systems for use in first- and second-stage thrust vector control of rocket engines. An overview of the test program is also presented. Designs for both first- and second-stage actuators employ redundant dc brushless, three-phase rare-earth permanent magnet motors. The first-stage actuator is about 28 hp per motor and uses a roller screw. Second-stage thrust vector control is implemented with a much smaller actuator of about 1 hp per motor. This actuator uses a gear drive with a recycling ball screw mechanism. An operational EMA is presented. This 6.5-in. actuator is capable of a stall force of 1350 pounds per motor and a frequency response of about 5 HZ.

  10. Vector control of induction motor without shaft encoder

    Microsoft Academic Search

    T. Ohtani; N. Takada; K. Tanaka

    1989-01-01

    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

  11. 40 CFR 258.22 - Disease vector control.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

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

  12. Vector ecology and integrated control procedures

    PubMed Central

    Laird, Marshall

    1963-01-01

    The elucidation of population regulatory mechanisms calls for exhaustive biological and ecological studies of whole ecosystems. Until lately, little effort was made to relate insect control activities to such a background, and the use of non-selective pesticides has often resulted in biotic equilibria being disrupted to the ultimate advantage of the organism under attack or of some other undesirable species. However, there is a growing realization in the field of economic entomology at large that biotic control agents usually constitute the major portion of the environmental resistance to increases in pest numbers and that insecticides should be fitted into the ecosystem, and not imposed upon it—in fact, that integrated control procedures are called for. The author considers such integrated procedures from the standpoint of vector control. His paper points out their potentialities in helping to solve resistance problems and in increasing the selectivity of control operations. It further suggests that they offer the means of achieving economical and lasting reductions of vector populations to levels at which human disease transmission is interrupted and pest problems lose much of their importance. PMID:20604165

  13. Controlling Vector Bessel Beams with Metasurfaces

    NASA Astrophysics Data System (ADS)

    Pfeiffer, Carl; Grbic, Anthony

    2014-10-01

    Unprecedented control of an electromagnetic wave front is demonstrated with reflectionless metasurfaces that can manipulate vector Bessel beams: cylindrical vector beams with a Bessel profile. First, two metasurfaces are developed to convert linearly and circularly polarized Gaussian beams into vector Bessel beams. Each unit cell of the metasurfaces provides polarization and phase control with high efficiency. Next, the reciprocal process is demonstrated: an incident radially polarized Bessel beam is transformed into collimated, linearly and circularly polarized beams. In this configuration, a planar Bessel beam launcher is integrated with a collimating metasurface lens to realize a low-profile lens-antenna. The lens-antenna achieves a high directivity (exceeding 20 dB) with a subwavelength overall thickness. Finally, a metasurface providing isotropic polarization rotation is used to transform a radially polarized Bessel beam into an azimuthally polarized Bessel beam. This work demonstrates that metasurfaces can be used to generate arbitrary combinations of radial and azimuthal polarizations for applications such as focus shaping or generating tractor beams.

  14. The Biological Control of the Malaria Vector

    PubMed Central

    Kamareddine, Layla

    2012-01-01

    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

  15. American Trypanosomiasis (Also Known as Chagas Disease) Diagnosis

    MedlinePLUS

    ... visit this page: About CDC.gov . Parasites - American Trypanosomiasis (also known as Chagas Disease) Parasites Home Share ... see the DPDx Web site: Chagas disease (American Trypanosomiasis) Diagnostic Procedures: Blood Specimens Print page Get email ...

  16. Chemotherapy of human African trypanosomiasis: current and future

    E-print Network

    Schnaufer, Achim

    Chemotherapy of human African trypanosomiasis: current and future prospects Alan H. Fairlamb- ment of African trypanosomiasis (sleeping sickness) were developed over 50 years ago. All for the development of safer, effective drugs are discussed. The chemotherapy of human African trypanosomiasis (HAT

  17. Electromechanical actuation for thrust vector control applications

    NASA Astrophysics Data System (ADS)

    Roth, Mary Ellen

    At present, actuation systems for the Thrust Vector Control (TVC) for launch vehicles are hydraulic systems. The Advanced Launch System (ALS), a joint initiative between NASA and the Air Force, is a launch vehicle that is designed to be cost effective, highly reliable and operationally efficient with a goal of reducing the cost per pound to orbit. As part of this initiative, an electromechanical actuation system is being developed as an attractive alternative to the hydraulic systems used today. NASA-Lewis is developing and demonstrating an Induction Motor Controller Actuation System with a 40 hp peak rating. The controller will integrate 20 kHz resonant link Power Management and Distribution (PMAD) technology and Pulse Population Modulation (PPM) techniques to implement Field Oriented Vector Control (FOVC) of a new advanced induction motor. Through PPM, multiphase variable frequency, variable voltage waveforms can be synthesized from the 20 kHz source. FOVC shows that varying both the voltage and frequency and their ratio (V/F), permits independent control of both torque and speed while operating at maximum efficiency at any point on the torque-speed curve. The driver and the FOVC will be microprocessor controlled. For increased system reliability, a Built-in Test (BITE) capability will be included. This involves introducing testability into the design of a system such that testing is calibrated and exercised during the design, manufacturing, maintenance and prelaunch activities. An actuator will be integrated with the motor controller for performance testing of the EMA TVC system. The design and fabrication of the motor controller is being done by General Dynamics Space Systems Division. The University of Wisconsin-Madison will assist in the design of the advanced induction motor and in the implementation of the FOVC theory. A 75 hp electronically controlled dynamometer will be used to test the motor controller in all four quadrants of operation using flight type control algorithms. Integrated testing of the controller and actuator will be conducted at a facility yet to be named. The EMA system described above is discussed in detail.

  18. A longitudinal survey of African animal trypanosomiasis in domestic cattle on the Jos Plateau, Nigeria: prevalence, distribution and risk factors

    PubMed Central

    2013-01-01

    Background Trypanosomiasis is a widespread disease of livestock in Nigeria and a major constraint to the rural economy. The Jos Plateau, Nigeria was free from tsetse flies and the trypanosomes they transmit due to its high altitude and the absence of animal trypanosomiasis attracted large numbers of cattle-keeping pastoralists to inhabit the plateau. The Jos Plateau now plays a significant role in the national cattle industry, accommodating approximately 7% of the national herd and supporting 300,000 pastoralists and over one million cattle. However, during the past two decades tsetse flies have invaded the Jos Plateau and animal trypanosomiasis has become a significant problem for livestock keepers. Methods In 2008 a longitudinal two-stage cluster survey on the Jos Plateau. Cattle were sampled in the dry, early wet and late wet seasons. Parasite identification was undertaken using species-specific polymerase chain reactions to determine the prevalence and distribution bovine trypanosomiasis. Logistic regression was performed to determine risk factors for disease. Results The prevalence of bovine trypanosomiasis (Trypanosoma brucei brucei, Trypanosoma congolense savannah, Trypanosoma vivax) across the Jos Plateau was found to be high at 46.8% (39.0 – 54.5%) and significant, seasonal variation was observed between the dry season and the end of the wet season. T. b. brucei was observed at a prevalence of 3.2% (1% – 5.5%); T. congolense at 27.7% (21.8% - 33.6%) and T. vivax at 26.7% (18.2% - 35.3%). High individual variation was observed in trypanosomiasis prevalence between individual villages on the Plateau, ranging from 8.8% to 95.6%. Altitude was found to be a significant risk factor for trypanosomiasis whilst migration also influenced risk for animal trypanosomiasis. Conclusions Trypanosomiasis is now endemic on the Jos Plateau showing high prevalence in cattle and is influenced by seasonality, altitude and migration practices. Attempts to successfully control animal trypanosomiasis on the Plateau will need to take into account the large variability in trypanosomiasis infection rates between villages, the influence of land use, and husbandry and management practices of the pastoralists, all of which affect the epidemiology of the disease. PMID:23958205

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

    Microsoft Academic Search

    Yifan Zhao; Thomas A. Lipo

    1995-01-01

    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

  20. An Anopheles transgenic sexing strain for vector control

    Microsoft Academic Search

    Flaminia Catteruccia; Jason P Benton; Andrea Crisanti

    2005-01-01

    Genetic manipulation of mosquito species that serve as vectors for human malaria is a prerequisite to the implementation of gene transfer technologies for the control of vector-borne diseases. Here we report on the development of transgenic sexing lines for the mosquito Anopheles stephensi, the principal vector of human malaria in Asia. Male mosquitoes, expressing enhanced green fluorescent protein (EGFP) under

  1. Hot gas thrust vector control motor

    NASA Astrophysics Data System (ADS)

    Berdoyes, Michel; Ellis, Russell A.

    1992-07-01

    A hot gas thrust vector control (HGTVC) motor developed in the framework of a Foreign Weapon Evaluation program is discussed. Two HGTVC versions were evaluated on the two nozzles of the program, normal injection with a blunt pintle and 10 deg upstream injection with a tapered pintle. The HGTVC system was tested on a modified ORBUS-1 motor which is based on two technologies, namely, a composite chamber polar boss (CPB) and a two-piece C-C nozzle which threads to the CPB and receives two HGVs embedded into its exit cone, 180 deg apart. It is concluded that the composite polar bosses and C-C nozzles performed successfully in both firings.

  2. Using Cell Phones for Mosquito Vector Surveillance and Control

    E-print Network

    Bieman, James M.

    and when mosquito control efforts should be focused. Since mosquito immatures (larvae and pupae) developUsing Cell Phones for Mosquito Vector Surveillance and Control S. Lozano-Fuentes, S. Ghosh, J. M--Novel, low-cost approaches to improving prevention and control of vector-borne diseases, such as mosquito

  3. Paratransgenic control of vector borne diseases.

    PubMed

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

    2011-01-01

    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. PMID:22110385

  4. Edinburgh Research Explorer A longitudinal survey of African animal trypanosomiasis in

    E-print Network

    Millar, Andrew J.

    Edinburgh Research Explorer A longitudinal survey of African animal trypanosomiasis in domestic trypanosomiasis in domestic cattle on the Jos Plateau, Nigeria: prevalence, distribution and risk factors. 2014 #12;RESEARCH Open Access A longitudinal survey of African animal trypanosomiasis in domestic

  5. LOW RF CONTROL FEEDBACK AND IQ VECTOR MODULATOR COMPENSATION FUNCTIONS.

    E-print Network

    Brookhaven National Laboratory

    RF gun and linac control circuits. Power and phase set points cover operational range of 20 dLOW RF CONTROL FEEDBACK AND IQ VECTOR MODULATOR COMPENSATION FUNCTIONS. M. Fedurin# , B. Malone, V. Yakimenko, BNL ATF, Upton, NY, 11973, U.S.A. Abstract I-Q vector modulator is key element of the gun

  6. Vector control of induction motor without shaft encoder

    Microsoft Academic Search

    Tsugutoshi Ohtani; Noriyuki Takada; Koji Tanaka

    1992-01-01

    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

  7. Exploiting the potential of vector control for disease prevention.

    PubMed Central

    Townson, H.; Nathan, M. B.; Zaim, M.; Guillet, P.; Manga, L.; Bos, R.; Kindhauser, M.

    2005-01-01

    Although vector control has proven highly effective in preventing disease transmission, it is not being used to its full potential, thereby depriving disadvantaged populations of the benefits of well tried and tested methods. Following the discovery of synthetic residual insecticides in the 1940s, large-scale programmes succeeded in bringing many of the important vector-borne diseases under control. By the late 1960s, most vector-borne diseases--with the exception of malaria in Africa--were no longer considered to be of primary public health importance. The result was that control programmes lapsed, resources dwindled, and specialists in vector control disappeared from public health units. Within two decades, many important vector-borne diseases had re-emerged or spread to new areas. The time has come to restore vector control to its key role in the prevention of disease transmission, albeit with an increased emphasis on multiple measures, whether pesticide-based or involving environmental modification, and with a strengthened managerial and operational capacity. Integrated vector management provides a sound conceptual framework for deployment of cost-effective and sustainable methods of vector control. This approach allows for full consideration of the complex determinants of disease transmission, including local disease ecology, the role of human activity in increasing risks of disease transmission, and the socioeconomic conditions of affected communities. PMID:16462987

  8. Space vector based current control schemes for voltage source inverters

    Microsoft Academic Search

    D. Wuest; F. Jenni

    1993-01-01

    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

  9. Towards the Atlas of human African trypanosomiasis

    PubMed Central

    Cecchi, Giuliano; Paone, Massimo; Franco, José R; Fèvre, Eric M; Diarra, Abdoulaye; Ruiz, José A; Mattioli, Raffaele C; Simarro, Pere P

    2009-01-01

    Background Updated, accurate and comprehensive information on the distribution of human African trypanosomiasis (HAT), also known as sleeping sickness, is critically important to plan and monitor control activities. We describe input data, methodology, preliminary results and future prospects of the HAT Atlas initiative, which will allow major improvements in the understanding of the spatial distribution of the disease. Methods Up-to-date as well as historical data collected by national sleeping sickness control programmes, non-governmental organizations and research institutes have been collated over many years by the HAT Control and Surveillance Programme of the World Health Organization. This body of information, unpublished for the most part, is now being screened, harmonized, and analysed by means of database management systems and geographical information systems (GIS). The number of new HAT cases and the number of people screened within a defined geographical entity were chosen as the key variables to map disease distribution in sub-Saharan Africa. Results At the time of writing, over 600 epidemiological reports and files from seventeen countries were collated and included in the data repository. The reports contain information on approximately 20,000 HAT cases, associated to over 7,000 different geographical entities. The oldest epidemiological records considered so far date back to 1985, the most recent having been gathered in 2008. Data from Cameroon, Central African Republic, Chad, Congo, Equatorial Guinea and Gabon from the year 2000 onwards were fully processed and the preliminary regional map of HAT distribution is presented. Conclusion The use of GIS tools and geo-referenced, village-level epidemiological data allow the production of maps that substantially improve on the spatial quality of previous cartographic products of similar scope. The significant differences between our preliminary outputs and earlier maps of HAT transmission areas demonstrate the strong need for this systematic approach to mapping sleeping sickness and point to the inaccuracy of any calculation of population at risk based on previous maps of HAT transmission areas. The Atlas of HAT will lay the basis for novel, evidence-based methodologies to estimate the population at risk and the burden of disease, ultimately leading to more efficient targeting of interventions. Also, the Atlas will help streamline future field data collection in those parts of Africa that still require it. PMID:19296837

  10. Social factors affecting seasonal variation in bovine trypanosomiasis on the Jos Plateau, Nigeria

    PubMed Central

    2013-01-01

    Background African Animal Trypanosomiasis (AAT) is a widespread disease of livestock in Nigeria and presents a major constraint to rural economic development. The Jos Plateau was considered free from tsetse flies and the trypanosomes they transmit due to its high altitude and this trypanosomiasis free status attracted large numbers of cattle-keeping pastoralists to the area. The Jos Plateau now plays a major role in the national cattle industry in Nigeria, accommodating approximately 7% of the national herd, supporting 300,000 pastoralists and over one million cattle. During the past two decades tsetse flies have invaded the Jos Plateau and animal trypanosomiasis has become a significant problem for livestock keepers. Here we investigate the epidemiology of trypanosomiasis as a re-emerging disease on the Plateau, examining the social factors that influence prevalence and seasonal variation of bovine trypanosomiasis. Methods In 2008 a longitudinal two-stage cluster survey was undertaken on the Jos Plateau. Cattle were sampled in the dry, early wet and late wet seasons. Parasite identification was undertaken using species-specific polymerase chain reactions to determine the prevalence and distribution of bovine trypanosomiasis. Participatory rural appraisal was also conducted to determine knowledge, attitudes and practices concerning animal husbandry and disease control. Results Significant seasonal variation between the dry season and late wet season was recorded across the Jos Plateau, consistent with expected variation in tsetse populations. However, marked seasonal variations were also observed at village level to create 3 distinct groups: Group 1 in which 50% of villages followed the general pattern of low prevalence in the dry season and high prevalence in the wet season; Group 2 in which 16.7% of villages showed no seasonal variation and Group 3 in which 33.3% of villages showed greater disease prevalence in the dry season than in the wet season. Conclusions There was high seasonal variation at the village level determined by management as well as climatic factors. The growing influence of management factors on the epidemiology of trypanosomiasis highlights the impact of recent changes in land use and natural resource competition on animal husbandry decisions in the extensive pastoral production system. PMID:24172046

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

    Microsoft Academic Search

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

    1995-01-01

    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

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

    Microsoft Academic Search

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

    1994-01-01

    The concept of a vector approximation method for a CSI-fed induction motor consists of the vector control and the shaping of a stator current wave. The vector approximation means that a desirable current space 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

  13. Advances in vector control of ac motor drives — A review

    Microsoft Academic Search

    A K Chattopadhyay

    1997-01-01

    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

  14. Cluster of African trypanosomiasis in travelers to Tanzanian national parks

    Microsoft Academic Search

    Tomas Jelinek; Zeno Bisoffi; Lucio Bonazzi; Thiel van P. P. A. M; Ulf Bronner; Albie de Frey; Svein Gunnar Gundersen; Paul McWhinney; Diego Ripamonti

    2002-01-01

    Game parks in Tanzania have long been considered to be at low risk for African trypanosomiasis; however, nine cases of the disease associated with these parks were recently reported. The outbreak was detected through TropNetEurop, a sentinel surveillance network of clinical sites throughout Europe. frican trypanosomiasis (sleeping sickness), a serious infection caused by a protozoan (Trypanosoma brucei), is usually spread

  15. Bovine trypanosomiasis in southern Tanzania: investigation into the incidence of infection and duration of chemoprophylaxis.

    PubMed

    Connor, R J; Mukangi, D J; Halliwell, R W

    1989-05-01

    Before implementing chemoprophylaxis to control bovine trypanosomiasis it is essential to have epidemiological data upon which to base control regimes. A study was conducted under natural tsetse challenge with two groups each of 12 calves grazing their first season. Group 1 received isometamidium treatments prophylactically at intervals during the rainy season and calves in group 2 were treated individually with diminazene as they become infected with trypanosomes. Infections were first detected in the unprotected calves and indicated that the onset of challenge was approximately four weeks after the rainy season began. Trypanosoma vivax accounted for 21 of the 30 infections detected in blood smears, and although one infection remained unspeciated, the remaining eight were T. congolense. It was concluded that a prophylactic regime beginning one month after the start of the rains with repeat treatments of isometamidium at 1 mg/kg at intervals of 10 weeks could be expected to give good control of trypanosomiasis at this location. PMID:2787560

  16. Control of vectors and insecticide resistance: Implications for disease control

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Effective management of insect and mite vectors of plant pathogens is of crucial importance to minimizing vector-borne diseases in crops. Insecticides play an important role in managing vector populations by reducing the number of individuals that can acquire and transmit a virus, thereby potentiall...

  17. Design and test of electromechanical actuators for thrust vector control

    Microsoft Academic Search

    J. R. Cowan; Rae Ann Weir

    1993-01-01

    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

  18. Genetically Distinct Glossina fuscipes fuscipes Populations in the Lake Kyoga Region of Uganda and Its Relevance for Human African Trypanosomiasis

    PubMed Central

    Echodu, Richard; Sistrom, Mark; Hyseni, Chaz; Enyaru, John; Okedi, Loyce; Aksoy, Serap; Caccone, Adalgisa

    2013-01-01

    Tsetse flies (Glossina spp.) are the sole vectors of Trypanosoma brucei—the agent of human (HAT) and animal (AAT) trypanosomiasis. Glossina fuscipes fuscipes (Gff) is the main vector species in Uganda—the only country where the two forms of HAT disease (rhodesiense and gambiense) occur, with gambiense limited to the northwest. Gff populations cluster in three genetically distinct groups in northern, southern, and western Uganda, respectively, with a contact zone present in central Uganda. Understanding the dynamics of this contact zone is epidemiologically important as the merger of the two diseases is a major health concern. We used mitochondrial and microsatellite DNA data from Gff samples in the contact zone to understand its spatial extent and temporal stability. We show that this zone is relatively narrow, extending through central Uganda along major rivers with south to north introgression but displaying no sex-biased dispersal. Lack of obvious vicariant barriers suggests that either environmental conditions or reciprocal competitive exclusion could explain the patterns of genetic differentiation observed. Lack of admixture between northern and southern populations may prevent the sympatry of the two forms of HAT disease, although continued control efforts are needed to prevent the recolonization of tsetse-free regions by neighboring populations. PMID:24199195

  19. Parallel and vector computation for stochastic optimal control applications

    NASA Technical Reports Server (NTRS)

    Hanson, F. B.

    1989-01-01

    A general method for parallel and vector numerical solutions of stochastic dynamic programming problems is described for optimal control of general nonlinear, continuous time, multibody dynamical systems, perturbed by Poisson as well as Gaussian random white noise. Possible applications include lumped flight dynamics models for uncertain environments, such as large scale and background random atmospheric fluctuations. The numerical formulation is highly suitable for a vector multiprocessor or vectorizing supercomputer, and results exhibit high processor efficiency and numerical stability. Advanced computing techniques, data structures, and hardware help alleviate Bellman's curse of dimensionality in dynamic programming computations.

  20. Implementation of a new fuzzy vector control of induction motor.

    PubMed

    Rafa, Souad; Larabi, Abdelkader; Barazane, Linda; Manceur, Malik; Essounbouli, Najib; Hamzaoui, Abdelaziz

    2014-05-01

    The aim of this paper is to present a new approach to control an induction motor using type-1 fuzzy logic. The induction motor has a nonlinear model, uncertain and strongly coupled. The vector control technique, which is based on the inverse model of the induction motors, solves the coupling problem. Unfortunately, in practice this is not checked because of model uncertainties. Indeed, the presence of the uncertainties led us to use human expertise such as the fuzzy logic techniques. In order to maintain the decoupling and to overcome the problem of the sensitivity to the parametric variations, the field-oriented control is replaced by a new block control. The simulation results show that the both control schemes provide in their basic configuration, comparable performances regarding the decoupling. However, the fuzzy vector control provides the insensitivity to the parametric variations compared to the classical one. The fuzzy vector control scheme is successfully implemented in real-time using a digital signal processor board dSPACE 1104. The efficiency of this technique is verified as well as experimentally at different dynamic operating conditions such as sudden loads change, parameter variations, speed changes, etc. The fuzzy vector control is found to be a best control for application in an induction motor. PMID:24629620

  1. Vector inversion diminishes the online control of antisaccades

    Microsoft Academic Search

    Matthew Heath; Jeffrey Weiler; Kendall Marriott; Timothy N. Welsh

    2011-01-01

    Antisaccades require the suppression of a stimulus-driven response (i.e., response suppression) and the computation of a movement\\u000a plan mirror-symmetrical to the location of a target (i.e., vector inversion). The goal of the present study was to determine\\u000a whether response suppression, vector inversion or both contribute to previously reported differences in the online control\\u000a of pro- and antisaccades (Heath in Exp

  2. Vector Control and Surveillance Operations in the Republic of Singapore

    PubMed Central

    Yoshikawa, Minako Jen

    2013-01-01

    Singapore is known for its comprehensive vector control methods that keep mosquito populations at low levels in the urban, tropical, and green city-state. This report describes the measures taken by the National Environment Agency on the basis of observations of vector control and surveillance activities in residential areas, construction sites, and foreign worker quarters. The government-led active operations dealt not only with mosquito control but also social issues in urban residential buildings where people with varying preferences live, the responsibilities of the business sector, and the education of multi-cultural/lingual residents and foreign workers. The public health measures implemented in Singapore offer useful ideas to countries/cities that have not yet established vector control programs against mosquito-borne infectious diseases. PMID:23874140

  3. Robust nonlinear control of vectored thrust aircraft

    NASA Technical Reports Server (NTRS)

    Doyle, John C.; Murray, Richard; Morris, John

    1993-01-01

    An interdisciplinary program in robust control for nonlinear systems with applications to a variety of engineering problems is outlined. Major emphasis will be placed on flight control, with both experimental and analytical studies. This program builds on recent new results in control theory for stability, stabilization, robust stability, robust performance, synthesis, and model reduction in a unified framework using Linear Fractional Transformations (LFT's), Linear Matrix Inequalities (LMI's), and the structured singular value micron. Most of these new advances have been accomplished by the Caltech controls group independently or in collaboration with researchers in other institutions. These recent results offer a new and remarkably unified framework for all aspects of robust control, but what is particularly important for this program is that they also have important implications for system identification and control of nonlinear systems. This combines well with Caltech's expertise in nonlinear control theory, both in geometric methods and methods for systems with constraints and saturations.

  4. Comparison of three larviciding options for malaria vector control

    Microsoft Academic Search

    S. D. Parvez; S. S. Al-Wahaibi

    A field study was carried out over 27 weeks in the south Batinah region of Oman to assess the efficiency and cost-effectiveness of different strategies for vector control of malaria. Three larviciding strat- egies for Anopheles spp. were applied to intervention areas and compared with a control area, with over 2000 breeding sites monitored for 6 months. The normal method

  5. [Monitoring human African trypanosomiasis in Central Africa in 2001 and cartography: results and perspectives].

    PubMed

    Lucas, P; Fanchey, G; Mouton, C; Jannin, J

    2001-01-01

    Cases of human African trypanosomiasis are distributed in changing geographical "outbreak areas" that can be visualized over time and space. Because of these variations in distribution, cartography and spatial analysis provide powerful tools for planning surveillance and control strategies. In 1996, the WHO in collaboration with the 15 most endemic countries in Central Africa undertook a program to develop a standardized inter-regional map of trypanosomiasis. This article provides a brief overview of the value of geomatic tools in public health followed by a description of the WHO program and its preliminary results. Also presented in this article is the Trypinfo site being development on the internet to increase the surveillance response-time and improve the feedback system. PMID:11803827

  6. Prospects for vector control through genetic manipulation of populations*

    PubMed Central

    Craig, George B.

    1963-01-01

    Since the development of insecticide-resistance and the consequent partial failure of the chemical approach to the control of disease vectors, interest in the biological approach has re-awakened. An aspect of the latter approach that is of great current interest is “autocidal control”—that is, the use of insects for their own destruction. This paper discusses the various ways in which genetic mechanisms can be used to bring about the destruction of harmful insects, with special reference to those of medical importance. The author considers that the prospects for the genetic control of vector species are good, but stresses that before genetic methods can be applied on a field scale certain requirements must be met. For example, genetic technology must be expanded, a firm background of genetic knowledge of vector species must be built up, a great deal more information about vector ecology, particularly population dynamics, must be acquired, and techniques for the mass production of vector insects under controlled conditions must be developed. PMID:20604180

  7. A Quasioptical Vector Interferometer for Polarization Control

    NASA Technical Reports Server (NTRS)

    Chuss, David T.; Wollack, Edward J.; Moseley, Harvey S.; Novak, Giles

    2005-01-01

    We present a mathematical description of a Quasioptical Vector Interferometer (QVI), a device that maps an input polarization state to an output polarization state by introducing a phase delay between two linear orthogonal components of the input polarization. The advantages of such a device over a spinning wave-plate modulator for measuring astronomical polarization in the far-infrared through millimeter are: 1. The use of small, linear motions eliminates the need for cryogenic rotational bearings, 2. The phase flexibility allows measurement of Stokes V as well as Q and U, and 3. The QVI allows for both multi-wavelength and broadband modulation. We suggest two implementations of this device as an astronomical polarization modulator. The first involves two such modulators placed in series. By adjusting the two phase delays, it is possible to use such a modulator to measure Stokes Q, U, and V for passbands that are not too large. Conversely, a single QVI may be used to measure Q and V independent of frequency. In this implementation, Stokes U must be measured by rotating the instrument. We conclude this paper by presenting initial laboratory results.

  8. The future of microbial insecticides as vector control agents.

    PubMed

    Federici, B A

    1995-06-01

    Insect vectors of human diseases are subject to diseases of their own caused by viruses, bacteria, fungi, protozoans, and nematodes. Over the past 30 years, many members of these groups have been evaluated as vector control agents, particularly for mosquito control. Most pathogens and nematodes occur primarily in larvae, and are only effective against this stage. The principal candidate control agents studied include iridescent and nuclear polyhedrosis viruses, the bacteria Bacillus thuringiensis and Bacillus sphaericus, the fungi Lagenidium giganteum, Culicinomyces clavosporus, and species of the genus Coelomomyces, the protozoan Nosema algerae, and the mermithid nematode Romanomermis culicivorax. Of these, the only one considered an operational success is the bacterium, Bacillus thuringiensis subsp. israelensis (B.t.i.), which has proven useful for control of both mosquito and blackfly larvae in programs where larviciding has been traditionally employed as a vector control tactic. The reasons for the success of B.t.i. are its cost-effectiveness and relative ease of use, which are due, respectively, to the ability of B.t.i. to be grown on artificial media and the development of formulations that can be applied using conventional insecticide application technology. Because few microbial insecticides are cost-effective, and those that are are only effective against larvae, these agents will likely play only a minor, but in some cases important, role in most future vector control programs. PMID:7595459

  9. Sensorless vector controller for a synchronous reluctance motor

    Microsoft Academic Search

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

    1998-01-01

    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

  10. Novel space vector based current controllers for PWM-inverters

    Microsoft Academic Search

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

    1991-01-01

    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

  11. Seroprevalence survey of American trypanosomiasis in Central Valley of Toluca.

    PubMed

    Quijano-Hernández, Israel A; Castro-Barcena, Alejandro; Barbabosa-Pliego, Alberto; Ochoa-García, Laucel; Del Ángel-Caraza, Javier; Vázquez-Chagoyán, Juan C

    2012-01-01

    American trypanosomiasis is a growing health issue in the Americas. México is an endemic country, where some locations such as in the State of México are considered highly prevalent. In the valley of Toluca city, the capital of the State of Mexico, there exists an apparent high prevalence in dogs. The absence of triatomine vectors suggests that dogs may not be infected. Therefore, we conducted a directed survey to domiciliated and nondomiciliated dogs to reassess dogs' T. cruzi seroprevalence status. HAI and ELISA serologic tests were applied to 124 and 167 serums of domiciliated and nondomiciliated dogs in the target city. Risk factors were estimated, but the results did not show any evidence to assess them. No domiciliated dogs tested positive to both tests, whereas only one non-domiciliated dog resulted positive. This animal may have acquired the infection in an endemic area and then migrated to Toluca. Research results indicate that T. cruzi infection is not actively transmitted among dogs, and it is pointed out that dogs are the main sentinel animal population to evaluate a possible expansion of the territory affected by Chagas' disease. PMID:22649293

  12. Genetic control of resistance to trypanosomiasis

    Microsoft Academic Search

    S. J. Kemp; A. Darvasi; M. Soller; A. J. Teale

    1996-01-01

    To map the genetic sources of trypanotolerance in mice, a linkage analysis of survival following trypanosome challenge was performed by selective genotyping in a large F2 population produced by crossing the resistant C57BL6 and susceptible BALBc inbred mouse lines. We report evidence of a chromosomal region of large effect, possibly comprising more than one resistance locus, on Chromosome 17; and

  13. Dengue and Chikungunya Vector Control Pocket Guide

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This technical guide consolidates information and procedures for surveillance and control of mosquitoes that transmit dengue and chikungunya viruses. The guide focuses on mosquitoes that transmit dengue but also makes reference to chikungunya and yellow fever because the pathogens that cause these ...

  14. Methods for control of tick vectors of Lyme Borreliosis

    USGS Publications Warehouse

    Jaenson, T.G.T.; Fish, D.; Ginsberg, H.S.; Gray, J.S.; Mather, T.N.; Piesman, J.

    1991-01-01

    During the IVth International Conference on Lyme Borreliosis in Stockholm, 1990, a workshop on control of Lyme disease vectors briefly reviewed: basic ecological principles for tick control; biocontrol of ticks; chemical control, including the use of repellents and use of permethrin-treated rodent nest material; tick control by habitat modification; and reduction of tick host availability. It was concluded that, although much research work remains, Lyme borreliosis is to a large extent a preventable infection. Avoidance of heavily tick-infested areas, personal protection using proper clothing, and prompt removal of attached ticks remain the most effective protective measures. Many other prophylactic measures are available and could be efficiently integrated into schemes to reduce the abundance of vectors. However, since the ecology of the infection varies greatly between different localities it may be necessary to apply different combinations of control methods in different endemic regions.

  15. African Trypanosomiasis Detection using Dempster-Shafer Theory

    E-print Network

    Maseleno, Andino

    2012-01-01

    World Health Organization reports that African Trypanosomiasis affects mostly poor populations living in remote rural areas of Africa that can be fatal if properly not treated. This paper presents Dempster-Shafer Theory for the detection of African trypanosomiasis. Sustainable elimination of African trypanosomiasis as a public-health problem is feasible and requires continuous efforts and innovative approaches. In this research, we implement Dempster-Shafer theory for detecting African trypanosomiasis and displaying the result of detection process. We describe eleven symptoms as major symptoms which include fever, red urine, skin rash, paralysis, headache, bleeding around the bite, joint the paint, swollen lymph nodes, sleep disturbances, meningitis and arthritis. Dempster-Shafer theory to quantify the degree of belief, our approach uses Dempster-Shafer theory to combine beliefs under conditions of uncertainty and ignorance, and allows quantitative measurement of the belief and plausibility in our identificat...

  16. Application of Lanczos vectors to control design of flexible structures

    NASA Technical Reports Server (NTRS)

    Craig, Roy R., Jr.; Su, Tzu-Jeng

    1990-01-01

    This report covers research conducted during the first year of the two-year grant. The research, entitled 'Application of Lanczos Vectors to Control Design of Flexible Structures' concerns various ways to obtain reduced-order mathematical models for use in dynamic response analyses and in control design studies. This report summarizes research described in several reports and papers that were written under this contract. Extended abstracts are presented for technical papers covering the following topics: controller reduction by preserving impulse response energy; substructuring decomposition and controller synthesis; model reduction methods for structural control design; and recent literature on structural modeling, identification, and analysis.

  17. Interruption of vector transmission by native vectors and “the art of the possible”

    PubMed Central

    Salvatella, Roberto; Irabedra, Pilar; Castellanos, Luis G

    2013-01-01

    In a recent article in the Reader’s Opinion, advantages and disadvantages of the certification processes of interrupted Chagas disease transmission (American trypanosomiasis) by native vector were discussed. Such concept, accepted by those authors for the case of endemic situations with introduced vectors, has been built on a long and laborious process by endemic countries and Subregional Initiatives for Prevention, Control and Treatment of Chagas, with Technical Secretariat of the Pan American Health Organization/World Health Organization, to create a horizon target and goal to concentrate priorities and resource allocation and actions. With varying degrees of sucess, which are not replaceable for a certificate of good practice, has allowed during 23 years to safeguard the effective control of transmission of Trypanosoma cruzi not to hundreds of thousands, but millions of people at risk conditions, truly “the art of the possible.” PMID:24626310

  18. Genetics and evolution of triatomines: from phylogeny to vector control

    PubMed Central

    Gourbière, S; Dorn, P; Tripet, F; Dumonteil, E

    2012-01-01

    Triatomines are hemipteran bugs acting as vectors of the protozoan parasite Trypanosoma cruzi. This parasite causes Chagas disease, one of the major parasitic diseases in the Americas. Studies of triatomine genetics and evolution have been particularly useful in the design of rational vector control strategies, and are reviewed here. The phylogeography of several triatomine species is now slowly emerging, and the struggle to reconcile the phenotypic, phylogenetic, ecological and epidemiological species concepts makes for a very dynamic field. Population genetic studies using different markers indicate a wide range of population structures, depending on the triatomine species, ranging from highly fragmented to mobile, interbreeding populations. Triatomines transmit T. cruzi in the context of complex interactions between the insect vectors, their bacterial symbionts and the parasites; however, an integrated view of the significance of these interactions in triatomine biology, evolution and in disease transmission is still lacking. The development of novel genetic markers, together with the ongoing sequencing of the Rhodnius prolixus genome and more integrative studies, will provide key tools to expanding our understanding of these important insect vectors and allow the design of improved vector control strategies. PMID:21897436

  19. Genetics and evolution of triatomines: from phylogeny to vector control.

    PubMed

    Gourbière, S; Dorn, P; Tripet, F; Dumonteil, E

    2012-03-01

    Triatomines are hemipteran bugs acting as vectors of the protozoan parasite Trypanosoma cruzi. This parasite causes Chagas disease, one of the major parasitic diseases in the Americas. Studies of triatomine genetics and evolution have been particularly useful in the design of rational vector control strategies, and are reviewed here. The phylogeography of several triatomine species is now slowly emerging, and the struggle to reconcile the phenotypic, phylogenetic, ecological and epidemiological species concepts makes for a very dynamic field. Population genetic studies using different markers indicate a wide range of population structures, depending on the triatomine species, ranging from highly fragmented to mobile, interbreeding populations. Triatomines transmit T. cruzi in the context of complex interactions between the insect vectors, their bacterial symbionts and the parasites; however, an integrated view of the significance of these interactions in triatomine biology, evolution and in disease transmission is still lacking. The development of novel genetic markers, together with the ongoing sequencing of the Rhodnius prolixus genome and more integrative studies, will provide key tools to expanding our understanding of these important insect vectors and allow the design of improved vector control strategies. PMID:21897436

  20. Solid rocket booster thrust vector control subsystem description

    NASA Technical Reports Server (NTRS)

    Redmon, J., Jr. (compiler)

    1983-01-01

    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 acquaint the reader with the operation, performance, and physical layout as well as the materials and instrumentation used.

  1. Attitude control of a spinning rocket via thrust vectoring

    SciTech Connect

    White, J.E.

    1990-12-19

    Two controllers are developed to provide attitude control of a spinning rocket that has a thrust vectoring capability. The first controller has a single-input/single-output design that ignores the gyroscopic coupling between the control channels. The second controller has a multi-input/multi-output structure that is specifically intended to account for the gyroscopic coupling effects. A performance comparison between the two approached is conducted for a range of roll rates. Each controller is tested for the ability to track step commands, and for the amount of coupling impurity. Both controllers are developed via a linear-quadratic-regulator synthesis procedure, which is motivated by the multi-input/multi-output nature of second controller. Time responses and a singular value analysis are used to evaluate controller performance. This paper describes the development and comparison of two controllers that are designed to provide attitude control of a spinning rocket that is equipped with thrust vector control. 12 refs., 13 figs., 2 tabs.

  2. Impact of iron loss on behavior of vector controlled induction machines

    Microsoft Academic Search

    Ernil Levi

    1995-01-01

    Vector control principles are derived under the assumption that iron core loss may be neglected. The paper discusses effects of this simplification on performance of vector controlled induction machines. Indirect stator, air gap and rotor flux oriented control of a current fed machine are dealt with, with the emphasis on indirect rotor flux oriented control. Models of vector controlled induction

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

    PubMed

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

    2013-03-01

    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

  4. Paratransgenesis Applied for Control of Tsetse Transmitted Sleeping Sickness

    Microsoft Academic Search

    Serap Aksoy; Brian Weiss; Geoffrey Attardo

    African trypanosomiasis (sleeping sickness) is a major cause of morbidity and mortality in Subsaharan Africa for human and\\u000a animal health. In the absence of effective vaccines and efficacious drugs, vector control is an alternative intervention tool\\u000a to break the disease cycle. This describes the vectorial and symbiotic biology of tsetse with emphasis on the current knowledge\\u000a on tsetse symbiont genomics

  5. Topographic models for predicting malaria vector breeding habitats: potential tools for vector control managers

    PubMed Central

    2013-01-01

    Background Identification of malaria vector breeding sites can enhance control activities. Although associations between malaria vector breeding sites and topography are well recognized, practical models that predict breeding sites from topographic information are lacking. We used topographic variables derived from remotely sensed Digital Elevation Models (DEMs) to model the breeding sites of malaria vectors. We further compared the predictive strength of two different DEMs and evaluated the predictability of various habitat types inhabited by Anopheles larvae. Methods Using GIS techniques, topographic variables were extracted from two DEMs: 1) Shuttle Radar Topography Mission 3 (SRTM3, 90-m resolution) and 2) the Advanced Spaceborne Thermal Emission Reflection Radiometer Global DEM (ASTER, 30-m resolution). We used data on breeding sites from an extensive field survey conducted on an island in western Kenya in 2006. Topographic variables were extracted for 826 breeding sites and for 4520 negative points that were randomly assigned. Logistic regression modelling was applied to characterize topographic features of the malaria vector breeding sites and predict their locations. Model accuracy was evaluated using the area under the receiver operating characteristics curve (AUC). Results All topographic variables derived from both DEMs were significantly correlated with breeding habitats except for the aspect of SRTM. The magnitude and direction of correlation for each variable were similar in the two DEMs. Multivariate models for SRTM and ASTER showed similar levels of fit indicated by Akaike information criterion (3959.3 and 3972.7, respectively), though the former was slightly better than the latter. The accuracy of prediction indicated by AUC was also similar in SRTM (0.758) and ASTER (0.755) in the training site. In the testing site, both SRTM and ASTER models showed higher AUC in the testing sites than in the training site (0.829 and 0.799, respectively). The predictability of habitat types varied. Drains, foot-prints, puddles and swamp habitat types were most predictable. Conclusions Both SRTM and ASTER models had similar predictive potentials, which were sufficiently accurate to predict vector habitats. The free availability of these DEMs suggests that topographic predictive models could be widely used by vector control managers in Africa to complement malaria control strategies. PMID:23324389

  6. Characteristics of a confined jet thrust vector control nozzle

    NASA Astrophysics Data System (ADS)

    Porzio, A. J.

    1984-12-01

    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 study, axial thrust, side force, and pressure distribution across the nozzle were measured. The parameters were SI pressure, primary short supply pressure, and SI port area. Results indicate that there is a lower limit to the supply pressure ratio (SI pressure to primary pressure) and SI mass flow below which, the nozzle will not produce side force. Also, above a primary pressure of 200 psig, the undeflected jet exhibits instabilities. Without SI, a 4 Hz oscillation occurs in the nozzle and switching jet attachment occurs near the throat.

  7. Investigation into the ecology of trypanosomiasis in the Lungawa Valley, Zambia 

    E-print Network

    Anderson, Neil Euan

    2009-01-01

    keeping is almost non-existent due to losses from trypanosomiasis and predation by wild animals. The aim of this study was to investigate the ecology of trypanosomiasis in this mult-host wildlife community, relatively free from anthropogenic influences...

  8. Comparison of three larviciding options for malaria vector control.

    PubMed

    Parvez, S D; Al-Wahaibi, S S

    2003-07-01

    A field study was carried out over 27 weeks in the south Batinah region of Oman to assess the efficiency and cost-effectiveness of different strategies for vector control of malaria. Three larviciding strategies for Anopheles spp. were applied to intervention areas and compared with a control area, with over 2000 breeding sites monitored for 6 months. The normal method of spraying 1 ppm temephos larvicide fortnightly was found to be less efficient and less cost-effective than using 0.5 ppm temephos applied weekly. A third, more environmentally favourable method, to search for vector larvae and treat only those breeding places, was more effective than fortnightly spraying but less effective than the weekly half dose and was the most expensive strategy. PMID:15748060

  9. Adaptive support vector regression for UAV flight control.

    PubMed

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

    2011-01-01

    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

  10. Fault tolerant vector control of induction motor drive

    NASA Astrophysics Data System (ADS)

    Odnokopylov, G.; Bragin, A.

    2014-10-01

    For electric composed of technical objects hazardous industries, such as nuclear, military, chemical, etc. an urgent task is to increase their resiliency and survivability. The construction principle of vector control system fault-tolerant asynchronous electric. Displaying recovery efficiency three-phase induction motor drive in emergency mode using two-phase vector control system. The process of formation of a simulation model of the asynchronous electric unbalance in emergency mode. When modeling used coordinate transformation, providing emergency operation electric unbalance work. The results of modeling transient phase loss motor stator. During a power failure phase induction motor cannot save circular rotating field in the air gap of the motor and ensure the restoration of its efficiency at rated torque and speed.

  11. FocusSpecific Clinical Profiles in Human African Trypanosomiasis Caused by Trypanosoma brucei

    E-print Network

    Schnaufer, Achim

    Focus­Specific Clinical Profiles in Human African Trypanosomiasis Caused by Trypanosoma brucei in human African trypanosomiasis (HAT) foci caused by Trypanosoma brucei rhodesiense (T Profiles in Human African Trypanosomiasis Caused by Trypanosoma brucei rhodesiense. PLoS Negl Trop Dis 4

  12. Chemical Validation of Trypanothione Synthetase A POTENTIAL DRUG TARGET FOR HUMAN TRYPANOSOMIASIS*S

    E-print Network

    Schnaufer, Achim

    Chemical Validation of Trypanothione Synthetase A POTENTIAL DRUG TARGET FOR HUMAN TRYPANOSOMIASIS for the treatment of human African trypanosomiasis, many potential drug targets in Trypa- nosoma brucei have been validation of TryS as a drug target in T. brucei. Human African trypanosomiasis (HAT)2 is endemic in sub

  13. Vectors

    NSDL National Science Digital Library

    Stern, David P. (David Peter), 1931-

    This web page, authored and curated by David P. Stern, 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.

  14. Forebody vortex control as a complement to thrust vectoring

    NASA Technical Reports Server (NTRS)

    Malcolm, G. N.; Ng, T. T.

    1990-01-01

    The desire to enhance the controllability of fighter aircraft at high angles of attack, particularly yaw control, has fostered an interest in both vectored thrust and active control of forebody vortices. This paper reviews several methods of forebody vortex control that have been investigated with water and wind tunnel tests of both generic and actual fighter configurations. The methods investigated include pneumatic or blowing techniques using surface-mounted jets and slots, surface suction, variable-height deployable strakes, and rotatable tip strakes. Flow visualization, and force and moment measurements have shown that all of the methods are effective in manipulating the forebody vortices over a wide range of angles of attack and sideslip, primarily through control over flow separation on the surface of the forebody. All are most effective when applied near the forebody tip. The advantages and limitations of the various methods are reviewed.

  15. Impulsive formation control using orbital energy and angular momentum vector

    NASA Astrophysics Data System (ADS)

    Choi, Yoonhyuk; Mok, Sunghoon; Bang, Hyochoong

    2010-09-01

    This paper presents a multi-impulsive formation control strategy using orbit energy-matching and relative angular momentum vector between leader and follower satellites. These conservative parameters (energy and angular momentum) provide analytical and global solutions for orbital maneuver design without relying on Gauss variational equations. The relationship with orbit element differences is discussed in the simplifying assumptions. The proposed approach is free from small variation assumptions, so that it is suitable for handling even the case of large error corrections. General limitations of impulse control and associated compensation maneuvers are also addressed.

  16. Harnessing mosquito-Wolbachia symbiosis for vector and disease control.

    PubMed

    Bourtzis, Kostas; Dobson, Stephen L; Xi, Zhiyong; Rasgon, Jason L; Calvitti, Maurizio; Moreira, Luciano A; Bossin, Hervé C; Moretti, Riccardo; Baton, Luke Anthony; Hughes, Grant L; Mavingui, Patrick; Gilles, Jeremie R L

    2014-04-01

    Mosquito species, members of the genera Aedes, Anopheles and Culex, are the major vectors of human pathogens including protozoa (Plasmodium sp.), filariae and of a variety of viruses (causing dengue, chikungunya, yellow fever, West Nile). There is lack of efficient methods and tools to treat many of the diseases caused by these major human pathogens, since no efficient vaccines or drugs are available; even in malaria where insecticide use and drug therapies have reduced incidence, 219 million cases still occurred in 2010. Therefore efforts are currently focused on the control of vector populations. Insecticides alone are insufficient to control mosquito populations since reduced susceptibility and even resistance is being observed more and more frequently. There is also increased concern about the toxic effects of insecticides on non-target (even beneficial) insect populations, on humans and the environment. During recent years, the role of symbionts in the biology, ecology and evolution of insect species has been well-documented and has led to suggestions that they could potentially be used as tools to control pests and therefore diseases. Wolbachia is perhaps the most renowned insect symbiont, mainly due to its ability to manipulate insect reproduction and to interfere with major human pathogens thus providing new avenues for pest control. We herein present recent achievements in the field of mosquito-Wolbachia symbiosis with an emphasis on Aedes albopictus. We also discuss how Wolbachia symbiosis can be harnessed for vector control as well as the potential to combine the sterile insect technique and Wolbachia-based approaches for the enhancement of population suppression programs. PMID:24252486

  17. Trypanosomiasis, cardiomyopathy and the risk of ischemic stroke.

    PubMed

    Carod-Artal, Francisco Javier

    2010-05-01

    American (Chagas disease) and African (sleeping sickness) trypanosomiasis are neglected tropical diseases and are a heavy burden in Latin America and Africa, respectively. Chagas disease is an independent risk factor for stroke. Apical aneurysm, heart failure and cardiac arrhythmias are associated with ischemic stroke in chagasic cardiomyopathy. Not all chagasic patients who suffer an ischemic stroke have a severe cardiomyopathy, and stroke may be the first manifestation of Chagas disease. Cardioembolism affecting the middle cerebral artery is the most common stroke subtype. Risk of recurrence is high and careful evaluation of recurrence risk should be addressed. Repolarization changes, low voltage and prolonged QT interval are common electrocardiography alterations in human African trypanosomiasis, and can be found in more than 70% of patients. Epidemiological studies are needed to asses the risk of stroke in African trypanosomiasis perimyocarditis. PMID:20450304

  18. Paratransgenesis: a promising new strategy for mosquito vector control.

    PubMed

    Wilke, André Barretto Bruno; Marrelli, Mauro Toledo

    2015-01-01

    The three main mosquito genera, Anopheles, Aedes and Culex, transmit respectively malaria, dengue and lymphatic filariasis. Current mosquito control strategies have proved unsuccessful, and there still is a substantial number of morbidity and mortality from these diseases. Genetic control methods have now arisen as promising alternative strategies, based on two approaches: the replacement of a vector population by disease-refractory mosquitoes and the release of mosquitoes carrying a lethal gene to suppress target populations. However, substantial hurdles and limitations need to be overcome if these methods are to be used successfully, the most significant being that a transgenic mosquito strain is required for every target species, making genetically modified mosquito strategies inviable when there are multiple vector mosquitoes in the same area. Genetically modified bacteria capable of colonizing a wide range of mosquito species may be a solution to this problem and another option for the control of these diseases. In the paratransgenic approach, symbiotic bacteria are genetically modified and reintroduced in mosquitoes, where they express effector molecules. For this approach to be used in practice, however, requires a better understanding of mosquito microbiota and that symbiotic bacteria and effector molecules be identified. Paratransgenesis could prove very useful in mosquito species that are inherently difficult to transform or in sibling species complexes. In this approach, a genetic modified bacteria can act by: (a) causing pathogenic effects in the host; (b) interfering with the host's reproduction; (c) reducing the vector's competence; and (d) interfering with oogenesis and embryogenesis. It is a much more flexible and adaptable approach than the use of genetically modified mosquitoes because effector molecules and symbiotic bacteria can be replaced if they do not achieve the desired result. Paratransgenesis may therefore become an important integrated pest management tool for mosquito control. PMID:26104575

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

    Microsoft Academic Search

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

    2004-01-01

    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

  20. Modelling the risk of being bitten by malaria vectors in a vector control area in southern Benin, west Africa

    PubMed Central

    2013-01-01

    Background The diversity of malaria vector populations, expressing various resistance and/or behavioural patterns could explain the reduced effectiveness of vector control interventions reported in some African countries. A better understanding of the ecology and distribution of malaria vectors is essential to design more effective and sustainable strategies for malaria control and elimination. Here, we analyzed the spatio-temporal risk of the contact between humans and the sympatric An. funestus and both M and S molecular forms of An. gambiae s.s. in an area of Benin with high coverage of vector control measures with an unprecedented level of resolution. Methods Presence-absence data for the three vectors from 1-year human-landing collections in 19 villages were assessed using binomial mixed-effects models according to vector control measures and environmental covariates derived from field and remote sensing data. After 8-fold cross-validations of the models, predictive maps of the risk of the contact between humans and the sympatric An. funestus and both molecular M and S forms of An. gambiae s.s. were computed. Results Model validations showed that the An. funestus, An. gambiae M form, and S form models provided an excellent (Area Under Curve>0.9), a good (AUC>0.8), and an acceptable (AUC>0.7) level of prediction, respectively. The distribution area of the probability of contact between human and An. funestus largely overlaps that of An. gambiae M form but this latter showed important seasonal variation. An. gambiae S form also showed seasonal variation but with different ecological preferences. Landscape data were useful to discriminate between the species’ distributions. Conclusions These results showed that available remote sensing data could help in predicting the human-vector contact for several species of malaria vectors at a village level scale. The predictive maps showed seasonal and spatial variations in the risk of human-vector contact for all three vectors. Such maps could help Malaria Control Programmes to implement more effective vector control strategy by taking into account to the dynamics of malaria vector species. PMID:23497700

  1. Emergence and Prevalence of Human Vector-Borne Diseases in Sink Vector Populations

    PubMed Central

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

    2012-01-01

    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

  2. Chemotherapy of human African trypanosomiasis: current and future prospects

    Microsoft Academic Search

    Alan H. Fairlamb

    2003-01-01

    Three of the four currently approved drugs for the treatment of African trypanosomiasis (sleeping sickness) were developed over 50 years ago. All of the current therapies are unsatisfactory for various reasons, including unacceptable toxicity, poor efficacy, undesirable route of administration, and drug resistance. The possible modes of action of these drugs are briefly reviewed, as are the possible mechanisms of

  3. Diagnostic and neuropathogenesis issues in human African trypanosomiasis

    Microsoft Academic Search

    Peter G. E. Kennedy

    2006-01-01

    Human African trypanosomiasis, also known as sleeping sickness, is caused by protozoan parasites of the genus Trypanosoma, and is a major cause of human mortality and morbidity. The East African and West African variants, caused by Trypanosma brucei rhodesiense and Trypanosoma brucei gambiense, respectively, differ in their presentation but the disease is fatal if untreated. Accurate staging of the disease

  4. [Technics of detection and diagnosis of African trypanosomiasis in humans].

    PubMed

    Stanghellini, A; Roux, J F

    1984-01-01

    The authors review the most recent and sophisticated laboratory techniques for screening and diagnosis of human african trypanosomiasis. Immunological screening: indirect immunofluorescence, card agglutination test. Parasitological diagnosis: hematocrit centrifuge technique, miniature anion exchange/centrifugation, cerebrospinal fluid centrifugation. For each of these techniques, the authors deal successively with principle and method, interest, possible applications. PMID:6394949

  5. Modeling and simulation of induction machine vector control with rotor resistance identification

    Microsoft Academic Search

    Scott Wade; Matthew W. Dunnigan; Barry W. Williams

    1997-01-01

    This paper shows that it is possible to use available commercial software to model and simulate a vector-controlled induction machine system. The components of a typical vector control system are introduced and methods given for incorporating these in the MATLAB\\/SIMULINK software package. The identification of rotor resistance is important in vector control, if high-performance torque control is needed, and modeling

  6. Vector control of the Brushless Doubly-Fed Machine for wind power generation

    Microsoft Academic Search

    Shiyi Shao; Ehsan Abdi; Richard McMahon

    2008-01-01

    The brushless Doubly-Fed Machine (BDFM) shows commercial benefits in the wind power generation. This paper presents a vector control scheme for the BDFM operating as a variable speed generator (VSG). The proposed vector controller is developed on the power winding stator flux frame, and can be used to control both speed and reactive power. The machine model and the control

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

    Microsoft Academic Search

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

    2000-01-01

    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

  8. Trypanosoma cruzi: adaptation to its vectors and its hosts

    PubMed Central

    Noireau, François; Diosque, Patricio; Jansen, Ana Maria

    2009-01-01

    American trypanosomiasis is a parasitic zoonosis that occurs throughout Latin America. The etiological agent, Trypanosoma cruzi, is able to infect almost all tissues of its mammalian hosts and spreads in the environment in multifarious transmission cycles that may or not be connected. This biological plasticity, which is probably the result of the considerable heterogeneity of the taxon, exemplifies a successful adaptation of a parasite resulting in distinct outcomes of infection and a complex epidemiological pattern. In the 1990s, most endemic countries strengthened national control programs to interrupt the transmission of this parasite to humans. However, many obstacles remain to the effective control of the disease. Current knowledge of the different components involved in elaborate system that is American trypanosomiasis (the protozoan parasite T. cruzi, vectors Triatominae and the many reservoirs of infection), as well as the interactions existing within the system, is still incomplete. The Triatominae probably evolve from predatory reduvids in response to the availability of vertebrate food source. However, the basic mechanisms of adaptation of some of them to artificial ecotopes remain poorly understood. Nevertheless, these adaptations seem to be associated with a behavioral plasticity, a reduction in the genetic repertoire and increasing developmental instability. PMID:19250627

  9. Adaptive modular vector field control for robot contact tasks in uncertain environment

    Microsoft Academic Search

    Yohei Saitoh; Zhiwei Luo; K. Watanabe

    2003-01-01

    This paper proposes an adaptive modular vector field control (AMVFC) approach for a robot manipulator to interact with its uncertain environmental geometric constraints. Started from the uncertain geometric model of the environment, the approach first parameterizes the desired velocity vector field of the robot by the weighted combination of a set of basis vector fields. Then, to overcome the influences

  10. Space Transportation System solid rocket booster thrust vector control system

    NASA Technical Reports Server (NTRS)

    Verble, A. J., Jr.; Mccool, A. A.; Potter, J. H.

    1980-01-01

    The Solid Rocket Booster, Thrust Vector Control (TVC) system was designed in accordance with the following requirements: self-contained power supply, failsafe operation, 20 flight uses after exposure to seawater landings, optimized cost, and component interchangeability. Trade studies were performed which led to the selection of a recirculating hydraulic system powered by Auxiliary Power Units (APU) which drive the hydraulic actuators and gimbal the solid rocket motor nozzle. Other approaches for the system design were studied in arriving at the recirculating hydraulic system powered by an APU. These systems must withstand the imposed environment and be usable for a minimum of 20 Space Transportation System flights with a minimum of refurbishment. The TVC system completed the required qualification and verification tests and is certified for the intended application. Substantiation data include analytical and test data.

  11. Space transportation system solid rocket booster thrust vector control system

    NASA Technical Reports Server (NTRS)

    Verble, A. J., Jr.; Mccool, A. A.; Potter, J. H.

    1979-01-01

    The Solid Rocket Booster, Thrust Vector Control (TVC) system was designed in accordance with the following requirements: self-contained power supply, fail-safe operation, 20 flight uses after exposure to seawater landings, optimized cost, and component interchangeability. Trade studies were performed which led to the selection of a recirculating hydraulic system powered by Auxiliary Power Units (APU) which drive the hydraulic actuators and gimbal the solid rocket motor nozzle. Other approaches for the system design were studied in arriving at the recirculating hydraulic system powered by an APU. These systems must withstand the imposed environment and be usable for a minimum of 20 Space Transportation System flights with a minimum of refurbishment. The TVC system has completed the major portion of qualification and verification tests and is prepared to be cleared for the first Shuttle flight (STS-1). Substantiation data will include analytical and test data.

  12. 67 FR 35822 - Prospective Grant of Exclusive License: Control of Arthropod Vectors of Parasitic Diseases

    Federal Register 2010, 2011, 2012, 2013, 2014

    2002-05-21

    ...AND HUMAN SERVICES Centers for Disease Control and Prevention Prospective...Arthropod Vectors of Parasitic Diseases AGENCY: Centers for Disease Control and Prevention (CDC...i) that the Centers for Disease Control and Prevention...

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

    Microsoft Academic Search

    L. Xu; J. Yao

    1992-01-01

    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

  14. Adult vector control, mosquito ecology and malaria transmission

    PubMed Central

    Brady, Oliver J.; Godfray, H. Charles J.; Tatem, Andrew J.; Gething, Peter W.; Cohen, Justin M.; McKenzie, F. Ellis; Alex Perkins, T.; Reiner, Robert C.; Tusting, Lucy S.; Scott, Thomas W.; Lindsay, Steven W.; Hay, Simon I.; Smith, David L.

    2015-01-01

    Background Standard advice regarding vector control is to prefer interventions that reduce the lifespan of adult mosquitoes. The basis for this advice is a decades-old sensitivity analysis of ‘vectorial capacity’, a concept relevant for most malaria transmission models and based solely on adult mosquito population dynamics. Recent advances in micro-simulation models offer an opportunity to expand the theory of vectorial capacity to include both adult and juvenile mosquito stages in the model. Methods In this study we revisit arguments about transmission and its sensitivity to mosquito bionomic parameters using an elasticity analysis of developed formulations of vectorial capacity. Results We show that reducing adult survival has effects on both adult and juvenile population size, which are significant for transmission and not accounted for in traditional formulations of vectorial capacity. The elasticity of these effects is dependent on various mosquito population parameters, which we explore. Overall, control is most sensitive to methods that affect adult mosquito mortality rates, followed by blood feeding frequency, human blood feeding habit, and lastly, to adult mosquito population density. Conclusions These results emphasise more strongly than ever the sensitivity of transmission to adult mosquito mortality, but also suggest the high potential of combinations of interventions including larval source management. This must be done with caution, however, as policy requires a more careful consideration of costs, operational difficulties and policy goals in relation to baseline transmission. PMID:25733562

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

    USGS Publications Warehouse

    Ginsberg, H.S.

    2001-01-01

    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.

  16. Eflornithine for the treatment of human African trypanosomiasis

    Microsoft Academic Search

    Christian Burri; Reto Brun

    2003-01-01

    Eflornithine is the only new molecule registered for the treatment of human African trypanosomiasis over the last 50 years. It is the drug used mainly as a back-up for melarsoprol refractory Trypanosoma brucei gambiense cases. The most commonly used dosage regimen for the treatment of T. b. gambiense sleeping sickness consists of 100 mg kg–1 body weight at intervals of 6 h for

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

    Microsoft Academic Search

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

    1999-01-01

    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

  18. Solid rocket booster thrust vector control subsystem test report (d-1)

    Microsoft Academic Search

    Pagan

    1978-01-01

    The results of the sequence of tests performed on the space shuttle solid rocket booster thrust vector control subsystem are presented. The operational characteristics of the thrust vector control subsystem components, as determined from the tests, are discussed. Special analyses of fuel consumption, basic steady state characteristics, GN2 spin, and actuator displacement were reviewed which will aid in understanding the

  19. Dengue Vector Control in Viet Nam Using Mesocyclops Through Community Participation

    Microsoft Academic Search

    Vu Sinh Nam; Nguyen Van Binh

    In Tanminh commune (Thuongtin district, Hatay province), a community-based vector control programme was implemented. Using local communication network and with the participation of health volunteers and schoolchildren under the direction of local authority, and in consultation with health staff, campaigns for the elimination of discarded containers and release of Mesocyclops proved to be highly effective for vector control and for

  20. Characterization of Truck Mounted Atomization Equipment Typically Used in Vector Control

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The control of arthropods that are vectors of human and animal disease is a high priority for both public health and military officials. As droplet size is a critical factor affecting vector control applications, the droplet size spectra produced by eleven sprayers and three spray formulations were...

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

    Microsoft Academic Search

    D. Hadiouche; H. Razik; A. Rezzoug

    2000-01-01

    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

  2. The Use of Small Voltage Vectors of Matrix Converters in Direct Torque Control of Induction Machines

    Microsoft Academic Search

    Carlos Ortega; Antoni Arias; Josep Ballcells; Cedric Caruanat; Cyril Spiterit; Joseph Ciliat

    2006-01-01

    The effects on torque performance when using small voltage vectors of Matrix Converters is investigated in this paper. These vectors are used in order to reduce the electromagnetic torque ripple which appears when Direct Torque Control technique is used in Induction Motors. Direct Torque Control for Induction Motors using Matrix Converters is reviewed and it is pointed out the problem

  3. Climate Change: Potential Affect on Pesticide Application for Vector Control

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Global climate change has and will in the future contribute to the global burden of vector-borne disease by affecting the spatial and tempral distribution of disease. These changes in disease distributions are a direct result of altering the ecology of immature and adult habitats of insect vectors....

  4. High-speed current dq PI controller for vector controlled PMSM drive.

    PubMed

    Marufuzzaman, Mohammad; Reaz, Mamun Bin Ibne; Rahman, Labonnah Farzana; Chang, Tae Gyu

    2014-01-01

    High-speed current controller for vector controlled permanent magnet synchronous motor (PMSM) is presented. The controller is developed based on modular design for faster calculation and uses fixed-point proportional-integral (PI) method for improved accuracy. Current dq controller is usually implemented in digital signal processor (DSP) based computer. However, DSP based solutions are reaching their physical limits, which are few microseconds. Besides, digital solutions suffer from high implementation cost. In this research, the overall controller is realizing in field programmable gate array (FPGA). FPGA implementation of the overall controlling algorithm will certainly trim down the execution time significantly to guarantee the steadiness of the motor. Agilent 16821A Logic Analyzer is employed to validate the result of the implemented design in FPGA. Experimental results indicate that the proposed current dq PI controller needs only 50 ns of execution time in 40 MHz clock, which is the lowest computational cycle for the era. PMID:24574913

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

    NASA Astrophysics Data System (ADS)

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

    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.

  6. Immunosuppression in bovine trypanosomiasis: Field studies using foot-and-mouth disease vaccine and clostridial vaccine

    Microsoft Academic Search

    J. M. Scott; R. G. Pegram; P. H. Holmes; T. W. F. Pay; P. A. Knight; F. W. JENurbros; G. M. Urquhart

    1977-01-01

    The immunosuppressive effect of naturally acquired trypanosomiasis was investigated in four groups of zebu cattle maintained in an area of high tsetse fly challenge in Western Ethiopia. Two of the groups remained without chemoprophylaxis against trypanosomiasis and became parasitaemic. The animals of one of these two groups received a polyvalent foot-and-mouth disease vaccine and the cattle of the other group

  7. Net-Based Control Versus Rational Control. The Relation Between ITNC Vector Languages and Rational Relations

    Microsoft Academic Search

    N. W. Keesmaat; H. C. M. Kleijn

    1997-01-01

    .  ?An Individual Token Net Controller (or ITNC) is a particular type of state-machine decomposable Petri net that can be used\\u000a as a synchronization mechanism in concurrent systems consisting of a fixed number of sequential subsystems. In this paper\\u000a the family of ITNC vector languages is compared to the well-known family of rational relations. On the one hand it is proved

  8. Multichannel vector field control module for LLRF control of superconducting cavities

    SciTech Connect

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

    2007-06-01

    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.

  9. A 150kVA vector-controlled matrix converter induction motor drive

    Microsoft Academic Search

    Thomas F. Podlesak; Dimosthenis C. Katsis; Patrick W. Wheeler; Jon C. Clare; Lee Empringham; Michael Bland

    2005-01-01

    This paper describes the design, construction, and testing of a 150-kVA closed-loop vector-controlled matrix converter induction motor drive. The primary objective of this research effort is to evaluate the utility of the matrix converter in electric vehicle applications, primarily for motor control. A prototype converter has been built using 600-A 1400-V insulated gate bipolar transistors. Closed-loop vector control has been

  10. Using Haptic Vector Fields for Animation Motion Control Technical Report PCS-TR99-353

    E-print Network

    Using Haptic Vector Fields for Animation Motion Control Technical Report PCS-TR99-353 Bruce Randall, 1999 Abstract We are exploring techniques for animation authoring and editing using a haptic force defines a time-varying, higher-order vector field on a configura- tion space for the animation. A haptic

  11. Contrasting Population Structures of Two Vectors of African Trypanosomoses in Burkina Faso: Consequences for Control

    Microsoft Academic Search

    Naférima Koné; Jérémy Bouyer; Sophie Ravel; Marc J. B. Vreysen; Kouadjo T. Domagni; Sandrine Causse; Philippe Solano; Thierry de Meeûs

    2011-01-01

    BackgroundAfrican animal trypanosomosis is a major obstacle to the development of more efficient and sustainable livestock production systems in West Africa. Riverine tsetse species such as Glossina palpalis gambiensis Vanderplank and Glossina tachinoides Westwood are the major vectors. A wide variety of control tactics is available to manage these vectors, but their removal will in most cases only be sustainable

  12. VECTOR ASSOCIATIVE MAPS: UNSUPERVISED REAL-TIME ERROR-BASED LEARNING AND CONTROL OF MOVEMENT

    E-print Network

    Spence, Harlan Ernest

    is regulated by activation of a self-regulating Endogenous Random Generator (ERG) of training vectors. EachVECTOR ASSOCIATIVE MAPS: UNSUPERVISED REAL-TIME ERROR-BASED LEARNING AND CONTROL OF MOVEMENT-based learning. The models clarify how a child, or untrained robot, can learn to reach for objects that it sees

  13. Determining the spatial autocorrelation of dengue vector populations: influences of mosquito sampling method, covariables, and vector control.

    PubMed

    Azil, Aishah H; Bruce, David; Williams, Craig R

    2014-06-01

    We investigated spatial autocorrelation of female Aedes aegypti L. mosquito abundance from BG-Sentinel trap and sticky ovitrap collections in Cairns, north Queensland, Australia. BG-Sentinel trap collections in 2010 show a significant spatial autocorrelation across the study site and over a smaller spatial extent, while sticky ovitrap collections only indicate a non-significant, weak spatial autocorrelation. The BG-Sentinel trap collections were suitable for spatial interpolation using ordinary kriging and cokriging techniques. The uses of Premise Condition Index and potential breeding container data have helped improve our prediction of vector abundance. Semiovariograms and prediction maps indicate that the spatial autocorrelation of mosquito abundance determined by BG-Sentinel traps extends farther compared to sticky ovitrap collections. Based on our data, fewer BG-Sentinel traps are required to represent vector abundance at a series of houses compared to sticky ovitraps. A lack of spatial structure was observed following vector control treatment in the area. This finding has implications for the design and costs of dengue vector surveillance programs. PMID:24820568

  14. A Heading and Flight-Path Angle Control of Aircraft Based on Required Acceleration Vector

    NASA Astrophysics Data System (ADS)

    Yoshitani, Naoharu

    This paper describes a control of heading and flight-path angles of aircraft to time-varying command angles. The controller first calculates an acceleration command vector (acV), which is vertical to the velocity vector. acV consists of two components; the one is feedforward acceleration obtained from the rates of command angles, and the other is feedback acceleration obtained from angle deviations by using PID control law. A bank angle command around the velocity vector and commands of pitch and yaw rates are then obtained to generate the required acceleration. A roll rate command is calculated from bank angle deviation. Roll, pitch and yaw rate commands are put into the attitude controller, which can be composed of any suitable control laws such as PID control. The control requires neither aerodynamic coefficients nor online calculation of the inverse dynamics of the aircraft. A numerical simulation illustrates the effects of the control.

  15. Vector control for malaria and other mosquito-borne diseases. Report of a WHO study group.

    PubMed

    1995-01-01

    Since the Ministerial Conference on Malaria in 1992, which acknowledged the urgent need for worldwide commitment to malaria control, efforts have been directed to implementation of a Global Malaria Control Strategy. Vector control, an essential component of malaria control, has become less effective in recent years, partly as a result of poor use of alternative control tools, inappropriate use of insecticides, lack of an epidemiological basis for interventions, inadequate resources and infrastructure, and weak management. Changing environmental conditions, the behavioural characteristics of certain vectors, and resistance to insecticides have added to the difficulties. This report of a WHO Study Group provides guidelines for the planning, implementation and evaluation of cost-effective and sustainable vector control in the context of the Global Malaria Control Strategy. It reviews the available methods - indoor residual spraying, personal protection, larval control and environmental management - stressing the need for selective and flexible use of interventions according to local conditions. Requirements for data collection and the appropriate use of entomological parameters and techniques are discussed and priorities identified for the development of local capacity for vector control and for operational research. Emphasis is placed both on the monitoring and evaluation of vector control to ensure cost-effectiveness and on the development of strong managerial structures, which can support community participation and intersectoral collaboration and accommodate the control of other vector-borne diseases. The report concludes with recommendations aimed at promoting the targeted and efficient use of vector control in preventing and controlling malaria, thereby reducing the threat to health and socioeconomic development in many tropical countries. PMID:8540245

  16. The bionomics of the malaria vector Anopheles farauti in Northern Guadalcanal, Solomon Islands: issues for successful vector control

    PubMed Central

    2014-01-01

    Background The north coast of Guadalcanal has some of the most intense malaria transmission in the Solomon Islands. And, there is a push for intensified vector control in Guadalcanal, to improve the livelihood of residents and to minimize the number of cases, which are regularly exported to the rest of the country. Therefore, the bionomics of the target vector, Anopheles farauti, was profiled in 2007–08; which was after 20 years of limited surveillance during which time treated bed nets (ITNs) were distributed in the area. Methods In three villages on northern Guadalcanal, blood-seeking female mosquitoes were caught using hourly human landing catches by four collectors, two working indoors and two outdoors, from 18.00-06.00 for at least two nights per month from July 2007 to June 2008. The mosquitoes were counted, identified using morphological and molecular markers and dissected to determine parity. Results Seasonality in vector densities was similar in the three villages, with a peak at the end of the drier months (October to December) and a trough at the end of the wetter months (March to May). There was some variability in endophagy (indoor biting) and nocturnal biting (activity during sleeping hours) both spatially and temporally across the longitudinal dataset. The general biting pattern was consistent throughout all sample collections, with the majority of biting occurring outdoors (64%) and outside of sleeping hours (65%). Peak biting was 19.00-20.00. The proportion parous across each village ranged between 0.54-0.58. Parity showed little seasonal trend despite fluctuations in vector densities over the year. Conclusion The early, outdoor biting behaviour of An. farauti documented 20 years previously on north Guadalcanal was still exhibited. It is possible that bed net use may have maintained this biting profile though this could not be determined unequivocally. The longevity of these populations has not changed despite long-term ITN use. This early, outdoor biting behaviour led to the failure of the eradication programme and is likely responsible for the continued transmission in Guadalcanal following the introduction of ITNs. Other vector control strategies which do not rely on the vector entering houses are needed if elimination or intensified control is to be achieved. PMID:24528850

  17. Human African trypanosomiasis in non-endemic countries.

    PubMed

    Sudarshi, Darshan; Brown, Mike

    2015-02-01

    Human African trypanosomiasis (HAT) or sleeping sickness is a parasitic disease, acquired by the bite of an infected tsetse fly. In non-endemic countries HAT is rare, and therefore the diagnosis may be delayed leading to potentially fatal consequences. In this article the clinical presentation, diagnosis and treatment of the two forms of HAT are outlined. Rhodesiense HAT is an acute illness that presents in tourists who have recently visited game parks in Eastern or Southern Africa, whereas Gambiense HAT has a more chronic clinical course, in individuals from West or Central Africa. PMID:25650203

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

    NASA Astrophysics Data System (ADS)

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

    1992-07-01

    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.

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

    E-print Network

    Bomblies, Arne

    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 ...

  20. The potential for environmental management to contribute to malaria vector control in western Niger

    E-print Network

    Gianotti, Rebecca L. (Rebecca Louise)

    2008-01-01

    This thesis investigated the potential for environmental management techniques to contribute to malaria vector control in Niger, with a case study on Banizoumbou village in western Niger. Numerical modeling was used to ...

  1. Overview of current situation of dengue and dengue vector control

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dengue is the most important arbovirus of humans in the world. It is caused by one of four closely related virus serotypes whose primary vector is Aedes aegypti and secondarily by Ae. albopictus. A global dengue pandemic began in Southeast Asia after World War II and has intensified during the las...

  2. Olfactory disruption: towards controlling important insect vectors of disease

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chemical repellents are used to decrease contacts between insect disease vectors and their hosts, thus reducing the probability of disease transmission. The molecular mechanisms by which repellents have their effects are poorly understood and remain a controversial topic. Here we present recent re...

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

    Microsoft Academic Search

    Bon-Ho Bae; Seung-Ki Sul; Jeong-Hyeck Kwon; Jong-Sub Shin

    2001-01-01

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

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

    Microsoft Academic Search

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

    2003-01-01

    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

  5. Optimal Control of Vector-Virus-Plant Interactions: The Case of Potato Leafroll Virus Net Necrosis

    Microsoft Academic Search

    Thomas L. Marsh; Ray G. Huffaker; Garrell E. Long

    2000-01-01

    This paper introduces a new specification to the economic pest management literature designed to optimally manage vector-virus-plant interactions for a single crop. The viral, insect-vector, and plant-host stocks are treated as renewable resources and conjunctively controlled in a discrete-time control framework subject to crop quality standards established in marketing contracts. The result is a conceptual integrated pest management model providing

  6. A V2G vector control model of electric car charging and discharging machine

    Microsoft Academic Search

    Xiaolei Wang; Pan Yan; Liang Yang; Wendao Yao; Guangwen Shi

    2011-01-01

    circuit topology structure of electric vehicle charging and discharging inverter based on space vector is presented. The control strategy uses rotation vector of the directional three-phase active tide reversible PWM converter, and the circuit topology is two-way control DC\\/DC converter with double buck reversible structure. In order to improve the efficiency of the charging and discharging machine, the main circuit

  7. Developmental Testing of Electric Thrust Vector Control Systems for Manned Launch Vehicle Applications

    NASA Technical Reports Server (NTRS)

    Bates, Lisa B.; Young, David T.

    2012-01-01

    This paper describes recent developmental testing to verify the integration of a developmental electromechanical actuator (EMA) with high rate lithium ion batteries and a cross platform extensible controller. Testing was performed at the Thrust Vector Control Research, Development and Qualification Laboratory at the NASA George C. Marshall Space Flight Center. Electric Thrust Vector Control (ETVC) systems like the EMA may significantly reduce recurring launch costs and complexity compared to heritage systems. Electric actuator mechanisms and control requirements across dissimilar platforms are also discussed with a focus on the similarities leveraged and differences overcome by the cross platform extensible common controller architecture.

  8. A Novel Sliding Mode Observer with Adaptive Feedback Gain for PMSM Sensorless Vector Control

    Microsoft Academic Search

    S. Chi; Z. Zhang; L. Xu

    2007-01-01

    A novel sliding mode observer (SMO) with adaptive feedback gain is presented for sensorless vector control of permanent magnet synchronous machines (PMSM). The rotor position angle is estimated based on the equivalent control in the sliding mode observer. By selecting adaptive feedback gain, the equivalent control has the same constant magnitude as rotor flux over full speed range. Compared to

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

    Microsoft Academic Search

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

    1990-01-01

    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-

  10. Indirect vector control of electric drives employing induction motor with forced dynamics

    Microsoft Academic Search

    Jan VITTEK; Juraj ALTUS; Jozef BUDAY; M. Rapsik

    2003-01-01

    The contribution presents an extension of indirect vector control of electric drives employing induction motors to 'forced dynamic control'. This control method offers an accurate realization of dynamic response profiles, which can be selected for given application by the user. The developed systems operate with shaft position encoder or shaft sensorless, when only the stator currents are measured, the applied

  11. Support vector machine model based predictive pid control system for cement rotary kiln

    Microsoft Academic Search

    Zheng Li

    2010-01-01

    The rotary kiln calcination is the most important part of cement production including complicated physical and chemical reaction processes with large inertia, pure hysteresis, nonlinearity and strong coupling characteristics. Considering the need of advanced process control in cement industry, this paper presents the application of support vector machine modeling and generalized predictive control PID control algorithm to the conventional cement

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

    Microsoft Academic Search

    Roberto Cárdenas; Rubén Peña; Greg Asher; Jon Clare

    2004-01-01

    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

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

    Microsoft Academic Search

    Hao Lu; Yunhua Li; Chenglin Zhu

    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

  14. Control of arbovirus diseases: is the vector the weak link?

    Microsoft Academic Search

    B. J. Beaty

    Arthropod-borne virus (arbovirus) diseases (ABVDs) remain major threats to human health and well-being and, as an epidemiologic\\u000a group, inflict an unacceptable health and economic burden on humans and animals, including livestock. The developed world\\u000a has been fortunate to have escaped much of the burden that arboviruses and their arthropod vectors inflict on humans in disease\\u000a endemic countries, but the introduction

  15. Design and test of a high power electromechanical actuator for thrust vector control

    NASA Astrophysics Data System (ADS)

    Cowan, J. R.; Myers, W. N.

    1992-07-01

    NASA-Marshall is involved in the development of electromechanical actuators (EMA) for thrust-vector control (TVC) system testing and implementation in spacecraft control/gimballing systems, with a view to the replacement of hydraulic hardware. TVC system control is furnished by solid state controllers and power supplies; a pair of resolvers supply position feedback to the controller for precise positioning. Performance comparisons between EMA and hydraulic TVC systems are performed.

  16. [Vector control in the epidemics of the Madagascar highlands].

    PubMed

    Randriantsimaniry, D

    1995-01-01

    The Plateau, or more precisely the highlands, cover most of the central part of Madagascar with an altitude higher than 1,000 m. There the climate is tropical with a wet and hot season, from October through April coincident with further outbreaks of malaria. This alternates with a dry season from May through September when the temperature is not favorable to the development of the vectors and the extrinsic cycle of the parasite. The malaria is unstable. The short season of transmission is sometimes amplified by abnormally abundant rain or higher than average temperatures. The population can hardly develop self-protection. The epidemics are deadly. The transmission essentially occurs with Anopheles arabiensis, a zoophile species, exophage and occasionally anthropophile and A. funestus anthropophile and endophile. Starting in 1949, a program for fighting malaria was founded on drug prophylaxis and spraying persistent insecticides within the homes. This approach gave spectacular results with a prolonged elimination of the disease, the consequence of which was the establishment of the Zone of Surveillance of the High Plateau (ZSHP). With decreasing efforts of the fight, the transmission progressively resumed starting in 1975 with outbreaks of epidemics. The most deadly outbreak was between 1984 and 1987, marked by an increase of morbidity and mortality. The factors which favored further outbreaks of malaria are listed as follows: 1) a slackening of the surveillance system; 2) the socio-economic context leading to the weakness of the national sanitary system and the inaccessibility of the antimalaria medication for the rural masses; 3) the reappearance of A. funestus, an excellent vector which had been eliminated by the treatments between 1949 and 1960; 4) after the previous elimination, the quasi-total absence of self-protection for the population when subjected to a series of cyclones; 5) movements of nonprotected travellers migrating for agricultural work from the highlands towards the coasts or the slopes which are zones of more stable malaria. Starting in 1988, the Madagascan sanitary authorities, with international and bilateral help, established a strategic approach based on early drug therapy and spraying within the homes with DTT pm 75 at a dose of 2 g/m2. These operations could cover some focalized zones with habitants, numbering 720,000 from 1988 to 1989; 380,000 from 1989 to 1990; 480,000 from 1990 to 1991; and 2,400,000 from 1993 to 1994. The evaluation of the efficacy of these methods in fighting malaria showed spectacular and conclusive results for the epidemiological plan, including less prevalence of the parasite, morbidity and mortality. In addition, there were important impacts on the vectors, including decreases of vector-human contact, residual fauna and longevity. PMID:8784547

  17. Approaches to vector control: new and trusted. 4. Appropriate technology for vector control: impregnated bed nets, polystyrene beads and fly traps.

    PubMed

    Curtis, C F

    1994-01-01

    There are social, economic and entomological problems with conventional insecticidal spraying methods for vector control. There is therefore interest in alternative technologies, especially the impregnation of bed nets with pyrethroid insecticides against malaria vectors. This method is cheap, socially acceptable and effective where bed nets are already widely used and where malaria transmission is not very intense. In holoendemic areas, and where people consider bed nets unaffordable, there are still unanswered questions. Whether pyrethroid resistance will be selected in anophelines also deserves more attention than it has so far attracted. Where Culex mosquitoes breed in confined sites such as pit latrines, the application of floating layers of polystyrene beads is a long-lasting and effective control method. There is increasing evidence that house flies are important agents in the mechanical transmission of diarrhoea due to Shigella. Simple fly traps can be an effective way of controlling house fly populations and this deserves comprehensive testing in tropical countries. PMID:8036653

  18. Direct torque control of induction machines using space vector modulation

    Microsoft Academic Search

    T. G. Habetler; F. Profumo; M. Pastorelli; L. M. Tolbert

    1991-01-01

    A control scheme for direct torque and flux control of induction machines based on the stator flux field orientation method is proposed. With the proposed predictive control scheme, an inverter duty cycle is directly based on the torque and flux errors, the transient reactance of the machine, and an estimated value of the voltage behind the transient reactance. A method

  19. Pastoral Livelihoods and the Epidemiology of Emergent Trypanosomiasis on the Jos Plateau, Nigeria 

    E-print Network

    Majekodunmi, Ayodele

    2012-01-01

    African trypanosomiasis is a widespread disease of livestock which is a major constraint to livestock production, mixed farming and the rural economy. The Jos Plateau in Nigeria was historically free of tsetse flies and ...

  20. Pastoral livelihoods and the epidemiology of emergent trypanosomiasis on the Jos Plateau, Nigeria 

    E-print Network

    Majekodunmi, Ayodele Oluwakemi

    2012-06-22

    African trypanosomiasis is a widespread disease of livestock which is a major constraint to livestock production, mixed farming and the rural economy. The Jos Plateau in Nigeria was historically free of tsetse flies and ...

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

    Microsoft Academic Search

    Geng Yang; Tung-Hai Chin

    1993-01-01

    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

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

    PubMed Central

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

    2012-01-01

    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. PMID:22885260

  3. Control of Ducted Fan Flying Object Using Thrust Vectoring

    NASA Astrophysics Data System (ADS)

    Miwa, Masafumi; Shigematsu, Yuki; Yamashita, Takashi

    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.

  4. Autonomous Control of an Autonomous Underwater Vehicle Towing a Vector Sensor Array

    E-print Network

    Schmidt, Henrik

    Autonomous Control of an Autonomous Underwater Vehicle Towing a Vector Sensor Array Michael R,arjunab@mit.edu Abstract-- This paper is about the autonomous control of an autonomous underwater vehicle (AUV the vehicles to adapt their missions and behave autonomously as events unfold. Conversely, practical concerns

  5. Sensorless Vector Control of PMSM Drives Equipped With Inverter Output Filter

    Microsoft Academic Search

    J. Salomaki; Antti Piippo; Marko Hinkkanen; Jorma Luomi

    2006-01-01

    The paper presents a sensorless vector control method for a permanent magnet synchronous motor when the output voltage of the PWM inverter is filtered by an LC filter. The dynamics of the LC filter are taken into account in the design of the controller and adaptive full-order observer. The use of the output filter does not require additional current or

  6. Application of genetic algorithms in sensorless speed vector-controlled AC speed adjusting system

    Microsoft Academic Search

    Liang Zhonghua; Hu Qing; Yu Haiyan; Ge Linjun; Yang Xia

    2001-01-01

    To solve the problems of the position estimation of an AC motor rotor depends upon the parameters of the motor. In this paper, a novel self-adaptive PI controller based on genetic algorithms is used in a sensorless speed vector control AC speed adjusting system. The robustness of the system is confirmed by simulation

  7. Robust vibration suppression of an adaptive circular composite plate for satellite thrust vector control

    Microsoft Academic Search

    Su Yan; Kougen Ma; Mehrdad N. Ghasemi-Nejhad

    2008-01-01

    In this paper, a novel application of adaptive composite structures, a University of Hawaii at Manoa (UHM) smart composite platform, is developed for the Thrust Vector Control (TVC) of satellites. The device top plate of the UHM platform is an adaptive circular composite plate (ACCP) that utilizes integrated sensors\\/actuators and controllers to suppress low frequency vibrations during the thruster firing

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

    Microsoft Academic Search

    Christos Mademlis; Nikos Margaris

    2002-01-01

    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.

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

    Microsoft Academic Search

    C. Schauder

    1992-01-01

    A model-reference adaptive system (MRAS) for the estimation of induction motor speed from measured terminal voltages and currents is described. 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

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

    SciTech Connect

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

    2000-04-01

    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.

  11. Transmission of chagas disease (American trypanosomiasis) by food.

    PubMed

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

    2010-01-01

    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

  12. SELECTION OF VARIABLES FOR REGULATORY CONTROL USING POLE VECTORS

    E-print Network

    Skogestad, Sigurd

    , where the measurements of the plant outputs are affected by noise. Which pair of one input and 1 Also noise) oe K ji (s) u j Fig. 1. Plant G and stabilizing control loop with pairing u j $ y i and the outputs to be controlled. Our concern in this paper are plants which need to be ``stabilized

  13. Voltage vector based control for PMSM in industry applications

    Microsoft Academic Search

    S. K. Dwivedi; M. Laursen; S. Hansen

    2010-01-01

    This paper is presenting a novel control strategy suitable for PMSM in industry applications such as fan and blower applications known from the heating, ventilation and air-conditioning industry or conveyor belt applications. Comparisons are made to the field oriented control typically used today in Industry applications for PMSM.

  14. Direct torque control of induction machines using space vector modulation

    Microsoft Academic Search

    Thomas G. Habetler; Francesco Profumo; Michele Pastorelli; Leon M. Tolbert

    1992-01-01

    A direct induction machine torque control method based on predictive, deadbeat control of the torque and flux is presented. By estimating the synchronous speed and the voltage behind the transient reactance, the change in torque and flux over the switching period is calculated. The stator voltage required to cause the torque and flux to be equal to their respective reference

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

    PubMed Central

    Gürtler, Ricardo E

    2011-01-01

    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 entities: a vector control program in charge of routine field operations (bug detection and insecticide spraying) and a disease control program in charge of screening blood donors, diagnosis, etiologic treatment and providing medical care to chronic patients. The challenge of sustainable suppression of bug infestation and Trypanosoma cruzi transmission can be met through integrated disease management, in which vector control is combined with active case detection and treatment to increase impact, cost-effectiveness and public acceptance in resource-limited settings. Multi-stakeholder involvement may add sustainability and resilience to the surveillance system. Chagas vector control and disease management must remain a regional effort within the frame of sustainable development rather than being viewed exclusively as a matter of health pertinent to the health sector. Sustained and continuous coordination between governments, agencies, control programs, academia and the affected communities is critical. PMID:19753458

  16. Impact of iron loss on behavior of vector controlled induction machines

    SciTech Connect

    Levi, E. [Liverpool John Moores Univ. (United Kingdom). School of Electrical Engineering] [Liverpool John Moores Univ. (United Kingdom). School of Electrical Engineering

    1995-11-01

    Vector control principles are derived under the assumption that iron core loss may be neglected. The paper discusses effects of this simplification on performance of vector controlled induction machines. Indirect stator, air gap and rotor flux oriented control of a current fed machine are dealt with, with the emphasis on indirect rotor flux oriented control. Models of vector controlled induction machines that account for the iron loss are derived, and the mechanism of core loss influence on behavior of the drives is highlighted. It is shown that detuning caused by neglecting the core loss will inevitably take place. The amount of detuning is investigated for steady-state operation, for all three types of vector control. Some insight into detuning during transient operation is provided for the case of indirect rotor flux oriented induction machine. The concluding part of the paper presents a new decoupling circuit for indirect rotor flux oriented control. The circuit accounts for iron loss and thus eliminates detuning which is otherwise present.

  17. Novel Technique of Contact Force Vector Determination Aimed at Control of Service Robot Arm and Estimation of Environment Stiffness

    E-print Network

    Tachi, Susumu

    of a robot arm according to applied force vector measured at the manipulator wrist [3]. However, the rest- 2771 - Novel Technique of Contact Force Vector Determination Aimed at Control of Service Robot of the applied force vector at any point of the robot arm and its technical realization. The experimental results

  18. 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...

  19. Suboptimal control of linear systems by state vector partitioning

    Microsoft Academic Search

    S. Vittal Rao; D. P. Atherton; R. Balasubramanian

    1980-01-01

    Several research workers [1-5] have studied the problem of designing suboptimal\\/near optimal regulators for high order plants. The implementation of the sub-optimal controllers has the advantage that a significant saving in computational effort may be realized with a small deterioration in system performance. The methods available for designing suboptimal controllers for large scale systems may be classified in the following

  20. Full fuzzy logic based vector control for permanent magnet synchronous motor

    NASA Astrophysics Data System (ADS)

    Yu, Jae Sung; Hwang, Sun Mo; Lee, Won Cheol; Won, Chung Yuen; Kim, Sang Hoon

    2005-12-01

    A full fuzzy-logic-based vector control for a permanent-magnet synchronous motor(PMSM) was proposed. The high-performance of the proposed fuzzy logic control(FLC)-based PMSM drive were investigated and compared to those obtained from the conventional proportional-integral(PI) controller at different conditions such as step change in command speed and load, etc. In the simulation and experimental results, the fuzzy-logic controller was employed in the speed and current controller. The comparative experimental results show that the FLC is more robust and, hence, found to be a suitable replacement of the conventional PI controller for the high-performance drive system.

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

    Microsoft Academic Search

    M. A. Rahman; M. A. Hoque

    1998-01-01

    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

  2. Vector control of induction motors without shaft transducers

    Microsoft Academic Search

    A. Fratta; A. Vagati; F. Villata

    1988-01-01

    A field oriented control scheme is proposed, not requiring any shaft transducer. The flux-estimation problems in such conditions are considered. A suitable method is proposed and its theoretical limits are outlined. A prototype system has been implemented, on this basis, and the experimental results are given, confirming the practical feasibility for a wide field of applications.

  3. SELECTION OF VARIABLES FOR REGULATORY CONTROL USING POLE VECTORS

    E-print Network

    Skogestad, Sigurd

    , where the measurements of the plant outputs are affected by noise. Which pair of one input and 1 Also -u1 -um -y1 -yl ? yi c ni (white noise) Kjis uj Fig. 1. Plant G and stabilizing control loop noise ni of unit intensity in each output yi. Find the best pairing uj $ yi, such that the plant

  4. A Cluster-Randomized Trial of Insecticide-Treated Curtains for Dengue Vector Control in Thailand

    PubMed Central

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

    2013-01-01

    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

  5. Low-Magnetic-Field Control of Electric Polarization Vector in a Helimagnet

    NASA Astrophysics Data System (ADS)

    Ishiwata, Shintaro; Taguchi, Yasujiro; Murakawa, Hiroshi; Onose, Yoshinori; Tokura, Yoshinori

    2008-03-01

    The mutual control of the electric and magnetic properties of a solid is currently of great interest because of the possible application for novel electronic devices. We report on the low-magnetic-field (for example, B values of ±30 milliteslas) control of the polarization (P) vector in a hexaferrite, Ba2Mg2Fe12O22, which shows the helimagnetic spin structure with the propagation vector k0 parallel to [001]. The B-induced transverse conical spin structure carries the P vector directing perpendicular to both B and k0, in accord with the recently proposed spin-current model. Then, the oscillating or multidirectionally rotating B produces the cyclic displacement current via the flexible handling of the magnetic cone axis.

  6. American Trypanosomiasis (Also Known as Chagas Disease) Prevention and Control

    MedlinePLUS

    ... housing and spraying insecticide inside housing to eliminate triatomine bugs has significantly decreased the spread of Chagas disease. ... Disease General Information Detailed FAQs Blood Screening FAQs Triatomine Bug FAQs Epidemiology & Risk Factors Biology Disease Diagnosis Treatment ...

  7. Circadian entrainment by light and host in the Chagas disease vector, Triatoma infestans.

    PubMed

    Valentinuzzi, Verónica Sandra; Amelotti, Ivana; Gorla, David Eladio; Catalá, Silvia Susana; Ralph, Martin Roland

    2014-03-01

    Triatoma infestans (Reduviidae: Triatominae, "kissing bug") is the main insect vector of Trypanosoma cruzi, the causative agent of Chagas disease, a chronic trypanosomiasis infecting 10 million people world-wide. This hematophagous bug feeds on diurnal and nocturnal species during each host's quiescent time. As the hosts are also its major predators, kissing bugs are subjected to dual selective pressures from a single source. Therefore, synchronization of feeding with the host's behavior is critical to the insects' survival. We show that nonphotic signals linked to the host eclipse the role of light and dark as the primary circadian zeitgeber for these bugs, although light still strongly inhibits locomotor behavior directly. In nature, this combination provides the insect with great flexibility in organizing physiology and behavior: anticipating a quiescent host or avoiding its potential predation while remaining directly responsive to immediate environmental conditions. Manipulation of nonphotic entrainment could be a useful chronobiotic tool in the control of Chagas disease. PMID:24156522

  8. Solid rocket booster thrust vector control subsystem verification test (V-2) report

    NASA Technical Reports Server (NTRS)

    Pagan, B.

    1979-01-01

    The results of the verification testing sequence V-2 performed on the space shuttle solid rocket booster thrust vector control subsystem are presented. A detailed history of the hot firings plus additional discussion of the auxiliary power unit and the hydraulic component performance is presented. The test objectives, data, and conclusions are included.

  9. Hydrologic modeling to screen potential environmental management methods for malaria vector control in Niger

    Microsoft Academic Search

    Rebecca L. Gianotti; Arne Bomblies; Elfatih A. B. Eltahir

    2009-01-01

    This paper describes the first use of Hydrology-Entomology and Malaria Transmission Simulator (HYDREMATS), a physically based distributed hydrology model, to investigate environmental management methods for malaria vector control in the Sahelian village of Banizoumbou, Niger. The investigation showed that leveling of topographic depressions where temporary breeding habitats form during the rainy season, by altering pool basin microtopography, could reduce the

  10. Pneumatic motor powered Thrust Vector Control (TVC) for liquid propelled launch vehicles

    Microsoft Academic Search

    Mark C. Malone; P. S. Evans

    1992-01-01

    Recent studies performed for the Titan 4 launch vehicle indicate significant potential advantages in replacing the current stage 1 and 2 recirculating hydraulic TVC (thrust vector control) system with a PMA (pneumatic mechanical actuation) system. Some of the advantages of a PMA system over the recirculating hydraulic system include reduced part count and weight, reduced maintenance and life-cycle cost, and

  11. Simulation of FOC Vector Control of Induction Motor Based on LabVIEW

    Microsoft Academic Search

    Tao Wu; Yi-Lin Chi; Yu Guo; Chao Xu

    2009-01-01

    Based on the theory of vector control of the induction motor, a new method for modeling and simulation of induction motor field orientation based on LabVIEW is proposed. This paper discusses the calculation of the flux position, the realization of the SVPWM, the equivalent transformation. The reasonability and validity are verified by the simulation and experimentation. This method offers a

  12. A Novel Polygon Based 15Phase AC-DC Converter for Vector Controlled Induction Motor Drives

    Microsoft Academic Search

    Bhim Singh; G. Bhuvaneswari; Vipin Garg

    2007-01-01

    In this article, a new approach to improve power quality at AC mains in a vector controlled induction motor drive (VCIMD) is proposed. The novel multi-phase AC-DC converter, consisting of a reduced rating autotransformer, leading to savings in weight, size, and cost, results in reduction in harmonic current at AC mains. The resulting supply current is near sinusoidal in shape

  13. Standstill Parameter Identification of Vector-Controlled Induction Motors Using the Frequency Characteristics of Rotor Bars

    Microsoft Academic Search

    Young-Su Kwon; Jeong-Hum Lee; Sang-Ho Moon; Byung-Ki Kwon; Chang-Ho Choi; Jul-Ki Seok

    2009-01-01

    We propose a current injection-based estimator to identify accurately standstill induction motor (IM) parameters necessary for vector control. A mathematical model that faithfully represents the general deep bar effect is introduced. Then, two exciting signals with a different frequency are sequentially injected to track the parameters based on the frequency function of the rotor bar. The proposed methodology employs closed-loop

  14. Further evaluation of spray characterization of sprayers typically used in vector control

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Droplet size spectra from different sprayers used to generate sprays for controlling insects that may vector diseases were measured by a laser diffraction instrument. The objective of this work was to measure the droplet size generated by different sprayers with water- and oil-based spray solutions...

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

    Microsoft Academic Search

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

    1999-01-01

    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

  16. Intrusive versus domiciliated triatomines and the challenge of adapting vector control practices against Chagas disease

    PubMed Central

    Waleckx, Etienne; Gourbière, Sébastien; Dumonteil, Eric

    2015-01-01

    Chagas disease prevention remains mostly based on triatomine vector control to reduce or eliminate house infestation with these bugs. The level of adaptation of triatomines to human housing is a key part of vector competence and needs to be precisely evaluated to allow for the design of effective vector control strategies. In this review, we examine how the domiciliation/intrusion level of different triatomine species/populations has been defined and measured and discuss how these concepts may be improved for a better understanding of their ecology and evolution, as well as for the design of more effective control strategies against a large variety of triatomine species. We suggest that a major limitation of current criteria for classifying triatomines into sylvatic, intrusive, domiciliary and domestic species is that these are essentially qualitative and do not rely on quantitative variables measuring population sustainability and fitness in their different habitats. However, such assessments may be derived from further analysis and modelling of field data. Such approaches can shed new light on the domiciliation process of triatomines and may represent a key tool for decision-making and the design of vector control interventions. PMID:25993504

  17. Certifying achievement in the control of Chagas disease native vectors: what is a viable scenario?

    PubMed

    Hashimoto, Ken; Yoshioka, Kota

    2014-09-01

    As an evaluation scheme, we propose certifying for "control", as alternative to "interruption", of Chagas disease transmission by native vectors, to project a more achievable and measurable goal and sharing good practices through an "open online platform" rather than "formal certification" to make the key knowledge more accumulable and accessible. PMID:25317713

  18. Further consideration of an electromechanical thrust vector control actuator experiencing large magnitude collinear transient forces

    Microsoft Academic Search

    Virginia T. Byrd; Joey K. Parker

    1997-01-01

    Thrust vector control (TVC) for the Space Shuttle Main Engines (SSMEs) is accomplished by hydraulic servo actuators. Marshall Space Flight Center (MSFC) is developing electromechanical actuator technology to be physically and functionally interchangeable with the existing hydraulic actuator. One of the major concerns for this design task is the large transient loads experienced by the TVC during start-up and shut-down.

  19. Certifying achievement in the control of Chagas disease native vectors: what is a viable scenario?

    PubMed Central

    Hashimoto, Ken; Yoshioka, Kota

    2014-01-01

    As an evaluation scheme, we propose certifying for “control”, as alternative to “interruption”, of Chagas disease transmission by native vectors, to project a more achievable and measurable goal and sharing good practices through an “open online platform” rather than “formal certification” to make the key knowledge more accumulable and accessible. PMID:25317713

  20. Space Vector PWM Control Synthesis for a H-Bridge Drive in Electric Vehicles

    E-print Network

    Paris-Sud XI, Université de

    Magnet Synchronous Machine in Electric Vehicle application. First, a short survey of existing power operating mode. Then, a rigorous analysis of the margins left in the control strategy is presented--Motor drives, Inverters, Space vector pulse width modulation (SVPWM), Permanent magnet machines, Semiconductor

  1. Intrusive versus domiciliated triatomines and the challenge of adapting vector control practices against Chagas disease.

    PubMed

    Waleckx, Etienne; Gourbière, Sébastien; Dumonteil, Eric

    2015-05-01

    Chagas disease prevention remains mostly based on triatomine vector control to reduce or eliminate house infestation with these bugs. The level of adaptation of triatomines to human housing is a key part of vector competence and needs to be precisely evaluated to allow for the design of effective vector control strategies. In this review, we examine how the domiciliation/intrusion level of different triatomine species/populations has been defined and measured and discuss how these concepts may be improved for a better understanding of their ecology and evolution, as well as for the design of more effective control strategies against a large variety of triatomine species. We suggest that a major limitation of current criteria for classifying triatomines into sylvatic, intrusive, domiciliary and domestic species is that these are essentially qualitative and do not rely on quantitative variables measuring population sustainability and fitness in their different habitats. However, such assessments may be derived from further analysis and modelling of field data. Such approaches can shed new light on the domiciliation process of triatomines and may represent a key tool for decision-making and the design of vector control interventions. PMID:25993504

  2. A space vector modulation direct torque control for permanent magnet synchronous motor drive systems

    Microsoft Academic Search

    D. Sun; J. G. Zhu; Y. K. He

    2003-01-01

    To minimize the ripples of the electro-magnetic torque and flux linkage and to fix the variable switching frequency produced in the conventional direct torque control (DTC) system for permanent magnet synchronous motors, this paper proposes a space vector modulation (SVM) DTC concept. Both simulation and experimental results show that the proposed SVM DTC can dramatically improve the steady state performance

  3. Thailand momentum on policy and practice in local legislation on dengue vector control.

    PubMed

    Bhumiratana, Adisak; Intarapuk, Apiradee; Chujun, Suriyo; Kaewwaen, Wuthichai; Sorosjinda-Nunthawarasilp, Prapa; Koyadun, Surachart

    2014-01-01

    Over a past decade, an administrative decentralization model, adopted for local administration development in Thailand, is replacing the prior centralized (top-down) command system. The change offers challenges to local governmental agencies and other public health agencies at all the ministerial, regional, and provincial levels. A public health regulatory and legislative framework for dengue vector control by local governmental agencies is a national topic of interest because dengue control program has been integrated into healthcare services at the provincial level and also has been given priority in health plans of local governmental agencies. The enabling environments of local administrations are unique, so this critical review focuses on the authority of local governmental agencies responsible for disease prevention and control and on the functioning of local legislation with respect to dengue vector control and practices. PMID:24799896

  4. Thailand Momentum on Policy and Practice in Local Legislation on Dengue Vector Control

    PubMed Central

    Bhumiratana, Adisak; Intarapuk, Apiradee; Chujun, Suriyo; Kaewwaen, Wuthichai; Sorosjinda-Nunthawarasilp, Prapa; Koyadun, Surachart

    2014-01-01

    Over a past decade, an administrative decentralization model, adopted for local administration development in Thailand, is replacing the prior centralized (top-down) command system. The change offers challenges to local governmental agencies and other public health agencies at all the ministerial, regional, and provincial levels. A public health regulatory and legislative framework for dengue vector control by local governmental agencies is a national topic of interest because dengue control program has been integrated into healthcare services at the provincial level and also has been given priority in health plans of local governmental agencies. The enabling environments of local administrations are unique, so this critical review focuses on the authority of local governmental agencies responsible for disease prevention and control and on the functioning of local legislation with respect to dengue vector control and practices. PMID:24799896

  5. Clustering of Vector Control Interventions Has Important Consequences for Their Effectiveness: A Modelling Study

    PubMed Central

    Lutambi, Angelina Mageni; Chitnis, Nakul; Briët, Olivier J. T.; Smith, Thomas A.; Penny, Melissa A.

    2014-01-01

    Vector control interventions have resulted in considerable reductions in malaria morbidity and mortality. When universal coverage cannot be achieved for financial or logistical reasons, the spatial arrangement of vector control is potentially important for optimizing benefits. This study investigated the effect of spatial clustering of vector control interventions on reducing the population of biting mosquitoes. A discrete-space continuous-time mathematical model of mosquito population dynamics and dispersal was extended to incorporate vector control interventions of insecticide treated bednets (ITNs), Indoor residual Spraying (IRS), and larviciding. Simulations were run at varying levels of coverage and degree of spatial clustering. At medium to high coverage levels of each of the interventions or in combination was more effective to spatially spread these interventions than to cluster them. Suggesting that when financial resources are limited, unclustered distribution of these interventions is more effective. Although it is often stated that locally high coverage is needed to achieve a community effect of ITNs or IRS, our results suggest that if the coverage of ITNs or IRS are insufficient to achieve universal coverage, and there is no targeting of high risk areas, the overall effects on mosquito densities are much greater if they are distributed in an unclustered way, rather than clustered in specific localities. Also, given that interventions are often delivered preferentially to accessible areas, and are therefore clustered, our model results show this may be inefficient. This study provides evidence that the effectiveness of an intervention can be highly dependent on its spatial distribution. Vector control plans should consider the spatial arrangement of any intervention package to ensure effectiveness is maximized. PMID:24823656

  6. FPGA realization of space-vector PWM control IC for three-phase PWM inverters

    Microsoft Academic Search

    Ying-Yu Tzou; Hau-Jean Hsu

    1997-01-01

    This paper presents a new circuit realization of the space-vector pulse-width modulation (SVPWM) strategy. An SVPWM control integrated circuit (IC) has been developed using state of-the-art field-programmable gate array (FPGA) technology. The proposed SVPWM control scheme can be realized using only a single FPGA (XC4010) from Xilinx, Inc. The output fundamental frequency can be adjusted from 0.094 to 1500 Hz.

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

    PubMed

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

    2012-09-01

    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

  8. Genetic shifting: a novel approach for controlling vector-borne diseases

    PubMed Central

    Tabachnick, Walter J.

    2014-01-01

    Rendering populations of vectors of diseases incapable of transmitting pathogens through genetic methods has long been a goal of vector geneticists. We outline a method to achieve this goal that does not involve introduction of any new genetic variants to the target population. Rather we propose that shifting the frequencies of naturally occurring alleles that confer refractoriness to transmission can reduce transmission below a sustainable level. The program employs methods successfully used in plant and animal breeding. Because no artificially constructed genetically modified organisms (GMOs) are introduced into the environment, the method is minimally controversial. We use Aedes aegypti and dengue virus (DENV) for illustrative purposes, but point out the proposed program is generally applicable to vector-borne disease control. PMID:24794113

  9. Benefit of Insecticide-Treated Nets, Curtains and Screening on Vector Borne Diseases, Excluding Malaria: A Systematic Review and Meta-analysis

    PubMed Central

    Wilson, Anne L.; Dhiman, Ramesh C.; Kitron, Uriel; Scott, Thomas W.; van den Berg, Henk; Lindsay, Steven W.

    2014-01-01

    Introduction Insecticide-treated nets (ITNs) are one of the main interventions used for malaria control. However, these nets may also be effective against other vector borne diseases (VBDs). We conducted a systematic review and meta-analysis to estimate the efficacy of ITNs, insecticide-treated curtains (ITCs) and insecticide-treated house screening (ITS) against Chagas disease, cutaneous and visceral leishmaniasis, dengue, human African trypanosomiasis, Japanese encephalitis, lymphatic filariasis and onchocerciasis. Methods MEDLINE, EMBASE, LILACS and Tropical Disease Bulletin databases were searched using intervention, vector- and disease-specific search terms. Cluster or individually randomised controlled trials, non-randomised trials with pre- and post-intervention data and rotational design studies were included. Analysis assessed the efficacy of ITNs, ITCs or ITS versus no intervention. Meta-analysis of clinical data was performed and percentage reduction in vector density calculated. Results Twenty-one studies were identified which met the inclusion criteria. Meta-analysis of clinical data could only be performed for four cutaneous leishmaniasis studies which together showed a protective efficacy of ITNs of 77% (95%CI: 39%–91%). Studies of ITC and ITS against cutaneous leishmaniasis also reported significant reductions in disease incidence. Single studies reported a high protective efficacy of ITS against dengue and ITNs against Japanese encephalitis. No studies of Chagas disease, human African trypanosomiasis or onchocerciasis were identified. Conclusion There are likely to be considerable collateral benefits of ITN roll out on cutaneous leishmaniasis where this disease is co-endemic with malaria. Due to the low number of studies identified, issues with reporting of entomological outcomes, and few studies reporting clinical outcomes, it is difficult to make strong conclusions on the effect of ITNs, ITCs or ITS on other VBDs and therefore further studies be conducted. Nonetheless, it is clear that insecticide-treated materials such as ITNs have the potential to reduce pathogen transmission and morbidity from VBDs where vectors enter houses. PMID:25299481

  10. Further analysis of singular vector and ENSO predictability in the Lamont model--Part I: singular vector and the control

    E-print Network

    Chen, .Dake

    to initial conditions. The dynamical diagnosis shows that the total linear and nonlinear heating terms play perturbation growth in the central Pacific. Keywords ENSO Á Predictability Á Singular vector analysis 1Further analysis of singular vector and ENSO predictability in the Lamont model--Part I: singular

  11. An Adaptive Supervisory Sliding Fuzzy Cerebellar Model Articulation Controller for Sensorless Vector-Controlled Induction Motor Drive Systems

    PubMed Central

    Wang, Shun-Yuan; Tseng, Chwan-Lu; Lin, Shou-Chuang; Chiu, Chun-Jung; Chou, Jen-Hsiang

    2015-01-01

    This paper presents the implementation of an adaptive supervisory sliding fuzzy cerebellar model articulation controller (FCMAC) in the speed sensorless vector control of an induction motor (IM) drive system. The proposed adaptive supervisory sliding FCMAC comprised a supervisory controller, integral sliding surface, and an adaptive FCMAC. The integral sliding surface was employed to eliminate steady-state errors and enhance the responsiveness of the system. The adaptive FCMAC incorporated an FCMAC with a compensating controller to perform a desired control action. The proposed controller was derived using the Lyapunov approach, which guarantees learning-error convergence. The implementation of three intelligent control schemes—the adaptive supervisory sliding FCMAC, adaptive sliding FCMAC, and adaptive sliding CMAC—were experimentally investigated under various conditions in a realistic sensorless vector-controlled IM drive system. The root mean square error (RMSE) was used as a performance index to evaluate the experimental results of each control scheme. The analysis results indicated that the proposed adaptive supervisory sliding FCMAC substantially improved the system performance compared with the other control schemes. PMID:25815450

  12. Hyperlipidaemia in trypanosomiasis of naturally infected horses: possible cachexia-anorexia syndrome?

    PubMed

    Ranjithkumar, Muthusamy; Malik, Tauseef Ahmed; Saxena, Anju; Dan, Ananya; Sakthivel, Pillanatham Civalingam; Dey, Sahadeb

    2013-02-01

    Trypanosomiasis caused by Trypanosoma evansi commonly produces wasting disease with signs of emaciation and cachexia mainly at the end stage. The present study was conducted to explore the possible hyperlipaemia or hyperlipidaemia and its association with cachexia-anorexia in equine trypanosomiasis. Out of the fifteen confirmed animals, none of the plasma sample was opaque. There was a significant increase in plasma triglyceride, total cholesterol and blood urea nitrogen and a highly significant increase in low-density lipoprotein (LDL) levels. A mild increase in high-density lipoprotein (HDL) and very low-density lipoprotein levels were observed, while the relative percentage of HDL and LDL was altered with high significance. A moderate increase in triglyceride and highly significant increase in LDL might be the reasons for retention of appetite and lipolysis. Possible protein breakdown and presence of lipolysis might be the reasons for cachexia in equine trypanosomiasis. PMID:22836485

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

    PubMed Central

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

    2008-01-01

    Background Malaria transmission in most agricultural ecosystems is complex and hence the need for developing a holistic malaria control strategy with adequate consideration of socio-economic factors driving transmission at community level. A cross-sectional household survey was conducted in an irrigated ecosystem with the aim of investigating vector control practices applied and factors affecting their application both at household and community level. Methods Four villages representing the socio-economic, demographic and geographical diversity within the study area were purposefully selected. A total of 400 households were randomly sampled from the four study villages. Both semi-structured questionnaires and focus group discussions were used to gather both qualitative and quantitative data. Results The results showed that malaria was perceived to be a major public health problem in the area and the role of the vector Anopheles mosquitoes in malaria transmission was generally recognized. More than 80% of respondents were aware of the major breeding sites of the vector. Reported personal protection methods applied to prevent mosquito bites included; use of treated bed nets (57%), untreated bed nets (35%), insecticide coils (21%), traditional methods such as burning of cow dung (8%), insecticide sprays (6%), and use of skin repellents (2%). However, 39% of respondents could not apply some of the known vector control methods due to unaffordability (50.5%), side effects (19.9%), perceived lack of effectiveness (16%), and lack of time to apply (2.6%). Lack of time was the main reason (56.3%) reported for non-application of environmental management practices, such as draining of stagnant water (77%) and clearing of vegetations along water canals (67%). Conclusion The study provides relevant information necessary for the management, prevention and control of malaria in irrigated agro-ecosystems, where vectors of malaria are abundant and disease transmission is stable. PMID:18667091

  14. Use of floating layers of polystyrene beads to control populations of the filaria vector Culex quinquefasciatus.

    PubMed

    Curtis, C F; Malecela-Lazaro, M; Reuben, R; Maxwell, C A

    2002-12-01

    Floating layers of polystyrene beads suffocate mosquito larvae and pupae and inhibit egg laying. The layers are very durable in breeding sites with water contained within walls, as in wet pit latrines and soakage pits. In some areas such pits constitute an important breeding site for Culex quinquefasciatus. Trials have been conducted in communities in Zanzibar, Tanzania, and in Tamil Nadu, India, where such mosquito populations were the vectors of Wuchereria bancrofti. In each case, treatment of all the pits with polystyrene beads was integrated with mass treatment of the people with antifilarial drugs-in Zanzibar in 1988 with diethylcarbamazine (DEC) and in India in the 1990s with DEC plus ivermectin. The results were compared with those in communities with the mass drug treatment alone and with control communities with neither treatment. The polystyrene-bead treatments greatly and sustainably reduced the vector populations. Comparison of the communities after drug treatment ceased showed that this form of vector control contributed markedly to the prevention of a resurgence of filarial infection. Where Cx. quinquefasciatus breeding in pits form a major component of the vector population, use of polystyrene-bead layers could assist considerably in the process of eliminating lymphatic filariasis by mass drug administration. PMID:12625923

  15. Two-dimensional confined jet thrust vector control: Operating mechanisms and performance

    NASA Astrophysics Data System (ADS)

    Caton, Jeffrey L.

    1989-03-01

    An experimental investigation of two-dimensional confined jet thrust vector control nozzles was performed. Thrust vector control was accomplished by using secondary flow injection in the diverging section of the nozzle. Schlieren photographs and video tapes were used to study flow separation and internal shock structures. Nozzle performance parameters were determined for nozzle flow with and without secondary flows. These parameters included nozzles forces, vector angles, thrust efficiencies, and flow switching response times. Vector angles as great as 18 degrees with thrust efficiencies of 0.79 were measured. Several confined jet nozzles with variations in secondary flow port design were tested and results were compared to each other. Converging-diverging nozzles of similar design to the confined jet nozzles were also tested and results were compared to the confined jet nozzle results. Existing prediction models for nozzle side to axial force ratio were evaluated. A model for nozzle total forces based on shock losses that predicted values very close to actual results was developed.

  16. Biosynthesized silver nanoparticles using floral extract of Chrysanthemum indicum L.-potential for malaria vector control.

    PubMed

    Arokiyaraj, Selvaraj; Dinesh Kumar, Vannam; Elakya, Vijay; Kamala, Tamilselvan; Park, Sung Kwon; Ragam, Muthiah; Saravanan, Muthupandian; Bououdina, Mohomad; Arasu, Mariadhas Valan; Kovendan, Kalimuthu; Vincent, Savariar

    2015-07-01

    Mosquitoes transmit serious human diseases, causing millions of deaths every year. The use of synthetic insecticides to control vector mosquitoes has caused physiological resistance and adverse environmental effects in addition to high operational cost. Insecticides synthesized of natural products for vector control have been a priority in this area. In the present study, silver nanoparticles (Ag NPs) were green-synthesized using a floral extract of Chrysanthemum indicum screened for larvicidal and pupicidal activity against the first to fourth instar larvae and pupae of the malaria vector Anopheles stephensi mosquitoes. The synthesized Ag NPs were characterized by using UV-vis absorption, X-ray diffraction, transmission electron microscopy, and energy-dispersive X-ray spectroscopy techniques. The textures of the yielded Ag NPs were found to be spherical and polydispersed with a mean size in the range of 25-59 nm. Larvae and pupae were exposed to various concentrations of aqueous extract of C. indicum and synthesized Ag NPs for 24 h, and the maximum mortality was observed from the synthesized Ag NPs against the vector A. stephensi (LC50?=?5.07, 10.35, 14.19, 22.81, and 35.05 ppm; LC90?=?29.18, 47.15, 65.53, 87.96, and 115.05 ppm). These results suggest that the synthesized Ag NPs have the potential to be used as an ideal eco-friendly approach for the control of A. stephensi. Additionally, this study provides the larvicidal and pupicidal properties of green-synthesized Ag NPs with the floral extract of C. indicum against vector mosquito species from the geographical location of India. PMID:25637241

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

    PubMed Central

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

    2013-01-01

    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. PMID:23469310

  18. Vector control in cutaneous leishmaniasis of the old world: a review of literature.

    PubMed

    Kassi, Masoom; Kasi, Pashtoon Murtaza; Marri, Shah Muhammad; Tareen, Iqbal; Khawar, Talha

    2008-01-01

    Cutaneous Leishmaniasis (CL), a disfiguring disease, is prevalent in many parts of Pakistan and neighboring Afghanistan. Leishmaniasis is second only to malaria in terms of the number of people affected; it is a major public health issue with significant social stigma. Although the different methods to diagnose and treat the disease are well discussed in the literature, the role of vector control in the prevention of CL has been underemphasized. Both Pubmed and Ovid search engines were used to obtain articles on prevention and control of cutaneous leishmaniasis. These materials were then screened for articles pertaining to vector control only. The World Health Organization's website along with the Cochrane database were also searched for relevant text. From this qualitative review, it can be seen that many effective interventions exist. Considering the multitude of factors involved in transmission of CL and the various effective control measures tried and tested by investigators, an interdisciplinary approach involving more than one of the above interventions would make sense. The interventions selected would then depend on the incidence of CL in that particular area, the population being targeted, the reservoir, the particular vector, the environment, the acceptability/popularity of the intervention, and the availability of funds. PMID:18713582

  19. Opportunities for Improved Chagas Disease Vector Control Based on Knowledge, Attitudes and Practices of Communities in the Yucatan Peninsula, Mexico

    PubMed Central

    Rosecrans, Kathryn; Cruz-Martin, Gabriela; King, Ashley; Dumonteil, Eric

    2014-01-01

    Background Chagas disease is a vector-borne parasitic disease of major public health importance. Current prevention efforts are based on triatomine vector control to reduce transmission to humans. Success of vector control interventions depends on their acceptability and value to affected communities. We aimed to identify opportunities for and barriers to improved vector control strategies in the Yucatan peninsula, Mexico. Methodology/principal findings We employed a sequence of qualitative and quantitative research methods to investigate knowledge, attitudes and practices surrounding Chagas disease, triatomines and vector control in three rural communities. Our combined data show that community members are well aware of triatomines and are knowledgeable about their habits. However, most have a limited understanding of the transmission dynamics and clinical manifestations of Chagas disease. While triatomine control is not a priority for community members, they frequently use domestic insecticide products including insecticide spray, mosquito coils and plug-in repellents. Families spend about $32 US per year on these products. Alternative methods such as yard cleaning and window screens are perceived as desirable and potentially more effective. Screens are nonetheless described as unaffordable, in spite of a cost comparable to the average annual spending on insecticide products. Conclusion/Significance Further education campaigns and possibly financing schemes may lead families to redirect their current vector control spending from insecticide products to window screens. Also, synergism with mosquito control efforts should be further explored to motivate community involvement and ensure sustainability of Chagas disease vector control. PMID:24676038

  20. Hydrologic modeling to screen potential environmental management methods for malaria vector control in Niger

    NASA Astrophysics Data System (ADS)

    Gianotti, Rebecca L.; Bomblies, Arne; Eltahir, Elfatih A. B.

    2009-08-01

    This paper describes the first use of Hydrology-Entomology and Malaria Transmission Simulator (HYDREMATS), a physically based distributed hydrology model, to investigate environmental management methods for malaria vector control in the Sahelian village of Banizoumbou, Niger. The investigation showed that leveling of topographic depressions where temporary breeding habitats form during the rainy season, by altering pool basin microtopography, could reduce the pool persistence time to less than the time needed for establishment of mosquito breeding, approximately 7 days. Undertaking soil surface plowing can also reduce pool persistence time by increasing the infiltration rate through an existing pool basin. Reduction of the pool persistence time to less than the rainfall interstorm period increases the frequency of pool drying events, removing habitat for subadult mosquitoes. Both management approaches could potentially be considered within a given context. This investigation demonstrates that management methods that modify the hydrologic environment have significant potential to contribute to malaria vector control in water-limited, Sahelian Africa.

  1. An update on the incidence of dengue gaining strength in Saudi Arabia and current control approaches for its vector mosquito

    PubMed Central

    2014-01-01

    Background The cases of dengue reported earlier in the late 1990s from the Kingdom of Saudi Arabia (KSA) occurred in the cities of Jeddah and Makkah. Although the kingdom has ample financial resources to establish effective control measures for the dengue vector, numerous cases of dengue occur and fluctuate in numbers from year to year. This necessitates a serious review of the current vector control strategies being practiced in order to identify the existing shortcomings. This short report provides an update on epidemiology of dengue in KSA (specifically in cities of Jeddah and Makkah) with a critical look at the current vector control strategies. Findings In 2013, 4411 cases of dengue were reported, with 8 cases of mortality. This number of dengue incidence was four times higher compared to 2012. In 2013, the highest number of 1272 dengue cases was reported in May, while the lowest number (37) of cases was reported in September. Conclusions It is evident that the control strategies of the dengue vector presently employed are inadequate. There seems to be serious deficiencies in following proper scientific procedures during field application(s) of control materials against the vector as is evident by the increases in the number of dengue cases as well as frequent outbreaks of the vector mosquito populations. In this review, some specific suggestions are made to draw attention to the relevant KSA authorities of the possible reasons behind unsuccessful control results and as to how to improve the strategy of dengue vector control in the kingdom. PMID:24890567

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

    Microsoft Academic Search

    Jung-Ik Ha

    2010-01-01

    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

  3. A Kalman filtering technique for spacecraft attitude determination and control using Gibbs vector 

    E-print Network

    Tallant, Gregory Stephen

    1988-01-01

    KALMAN FILTERING 27 30 36 1. The Standard Filter Formulation 2. The Gibbs Vector Representation 36 42 V APPLICATION AND EVALUATION OF THE KALMAN FILTER: FEEDBACK CONTROL OF SPACECRAFT ROTATIONAL MANEUVERS 47 vii Page VI CASE STUDIES... that the Kalman filter was used successfully for spacecraft attitude estimation. Today the filter has found applications in many areas of aerospace engineering and its derivation is given 8-11 in many books. Aside from inadequate study, the failure to obtain...

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

    Microsoft Academic Search

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

    1991-01-01

    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

  5. The development of H-II rocket solid rocket booster thrust vector control system

    Microsoft Academic Search

    Hirokazu Nagai; Yukio Fukushima; Hiroo Kazama; Tatsuro Asai; Shunichi Okaya; Yasushi Watanabe; Shoji Muramatsu

    1990-01-01

    The development of the thrust-vector-control (TVC) system for the two solid rocket boosters (SRBs) of the H-II rocket, which was started in 1984 and completed in 1989, is described. Special attention is given to the system's design, the trade-off studies, and the evaluation of the SRB-TVC system performance, as well as to problems that occurred in the course of the

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

    Microsoft Academic Search

    R. Hamke; J. Rade; R. Weldin

    1992-01-01

    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

  7. Development of Novel Magnetic Encoder and Vector Control Method for Servo Control of High-Speed Motor

    NASA Astrophysics Data System (ADS)

    Hao, Shuanghui; Liu, Jie; Mizugaki, Yoshio

    This paper presents a novel unipolar magnetic encoder and a new Vector control method of AC servo which can enable the feedback of the rotor position with high accuracy in high speed occasion. The signal generator of encoder consists of three pairs of semiconductor hall elements and a rotor of alnico magnet with one pair of poles. This encoder is featured with the operation module and the communication module to transmit an angular data in the form of asynchronous serial transfer protocol. Besides, a delay compensation algorithm is proposed to ensure the accurate estimation of instant angular position and the estimation error is also analyzed. At last, an experimental apparatus was built for a 600W, 4 pairs of pole, at rated speed 20,000min-1, permanent-magnet synchronous motor drive and the proposed vector control scheme has been implemented. The experiment results supported the validity of the proposed magnetic encoder and vector control method for high-speed AC servo control within 0.05 % error of revolving speed.

  8. Progress in controlling the reinvasion of windborne vectors into the western area of the Onchocerciasis Control Programme in West Africa.

    PubMed

    Baker, R H; Guillet, P; Sékétéli, A; Poudiougo, P; Boakye, D; Wilson, M D; Bissan, Y

    1990-06-30

    Since vector control began in 1975, waves of Simulium sirbanum and S. damnosum s.str., the principal vectors of severe blinding onchocerciasis in the West African savannas, have reinvaded treated rivers inside the original boundaries of the Onchocerciasis Control Programme in West Africa. Larviciding of potential source breeding sites has shown that these 'savanna' species are capable of travelling and carrying Onchocerca infection for at least 500 km northeastwards with the monsoon winds in the early rainy season. Vector control has, therefore, been extended progressively westwards. In 1984 the Programme embarked on a major western extension into Guinea, Sierra Leone, western Mali, Senegal and Guinea-Bissau. The transmission resulting from the reinvasion of northern Côte d'Ivoire and Burkina Faso has been reduced by over 95%, but eastern Mali has proved more difficult to protect because of sources in both Guinea and Sierra Leone. Rivers in Sierra Leone were treated for the first time in 1989 and biting and transmission rates in Sierra Leone and Guinea fell by over 90%. Because of treatment problems in some complex rapids and mountainous areas, flies still reinvaded Mali, though biting rates were approximately 70% lower than those recorded before anti-reinvasion treatments started. It was concluded that transmission in eastern Mali has now been reduced to the levels required to control onchocerciasis. PMID:1976266

  9. In silico models for predicting vector control chemicals targeting Aedes aegypti.

    PubMed

    Devillers, J; Lagneau, C; Lattes, A; Garrigues, J C; Clémenté, M M; Yébakima, A

    2014-01-01

    Human arboviral diseases have emerged or re-emerged in numerous countries worldwide due to a number of factors including the lack of progress in vaccine development, lack of drugs, insecticide resistance in mosquitoes, climate changes, societal behaviours, and economical constraints. Thus, Aedes aegypti is the main vector of the yellow fever and dengue fever flaviviruses and is also responsible for several recent outbreaks of the chikungunya alphavirus. As for the other mosquito species, the A. aegypti control relies heavily on the use of insecticides. However, because of increasing resistance to the different families of insecticides, reduction of Aedes populations is becoming increasingly difficult. Despite the unquestionable utility of insecticides in fighting mosquito populations, there are very few new insecticides developed and commercialized for vector control. This is because the high cost of the discovery of an insecticide is not counterbalanced by the 'low profitability' of the vector control market. Fortunately, the use of quantitative structure-activity relationship (QSAR) modelling allows the reduction of time and cost in the discovery of new chemical structures potentially active against mosquitoes. In this context, the goal of the present study was to review all the existing QSAR models on A. aegypti. The homology and pharmacophore models were also reviewed. Specific attention was paid to show the variety of targets investigated in Aedes in relation to the physiology and ecology of the mosquito as well as the diversity of the chemical structures which have been proposed, encompassing man-made and natural substances. PMID:25275884

  10. Mapping Neglected Swimming Pools from Satellite Data for Urban Vector Control

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    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.

  11. Ecology of vector mosquitoes in Sri Lanka--suggestions for future mosquito control in rice ecosystems.

    PubMed

    Yasuoka, Junko; Levins, Richard

    2007-07-01

    Mosquito-borne diseases are a major public health threat in Asia. To explore effective mosquito control strategies in rice ecosystems from the ecological point of view, we carried out ecological analyses of vector mosquitoes in Sri Lanka. During the 18-month study period, 14 Anopheles, 11 Culex, 5 Aedes, 2 Mansonia, and 1 Armigeres species were collected, most of which are disease vectors for malaria, filariasis, Japanese encephalitis, or dengue in Sri Lanka and elsewhere in Asia. The density and occurrence of Anopheles and Culex species were the highest in seepage pools and paddy fields, where the majority of niche overlaps between larval mosquito and aquatic insect species were observed. All 7 aquatic insect species, which are larval mosquito predators, overlapped their niche with both Anopheles and Culex larvae. This suggests that conserving these aquatic insect species could be effective in controlling mosquito vectors in the study site. Correlations between several climatic factors and mosquito density were also analyzed, and weather conditions, including higher temperature, lower relative humidity, and higher wind velocity, were found to affect mosquito oviposition, propagation, and survival. These findings deepen our understanding of mosquito ecology and will strengthen future mosquito control strategies in rice ecosystems in Asia. PMID:17883002

  12. Application of Lanczos vectors to control design of flexible structures, part 2

    NASA Technical Reports Server (NTRS)

    Craig, Roy R., Jr.; Su, Tzu-Jeng

    1992-01-01

    This report covers the period of the grant from January 1991 until its expiration in June 1992. Together with an Interim Report (Ref. 9), it summarizes the research conducted under NASA Grant NAG9-357 on the topic 'Application of Lanczos Vectors to Control Design of Flexible Structures.' The research concerns various ways to obtain reduced-order mathematical models of complex structures for use in dynamics analysis and in the design of control systems for these structures. This report summarizes the research.

  13. Silver nanoparticles: a possibility for malarial and filarial vector control technology.

    PubMed

    Soni, Namita; Prakash, Soam

    2014-11-01

    Green synthesis technology is one of the rapid, reliable and best routes for the synthesis of silver nanoparticles (AgNPs). There are bioactive compounds with enormous potential in Azadirachta indica (Neem). The extraordinary mosquitoes warrant nanotechnology to integrate with novel molecules. This will be sustainable technology for future. Here, we synthesized AgNPs using aqueous extracts of leaves and bark of Az. indica (Neem). We tested AgNPs as larvicides, pupicides and adulticides against the malaria vector Anopheles stephensi and filariasis vector Culex quinquefasciatus. The results were obtained using UV-visible spectrophotometer and the images were recorded with a transmission electron microscope (TEM). The efficacy tests were then performed at different concentrations varying many hours by probit analysis. The synthesized AgNPs were spherical in shape and with varied sizes (10.47-nm leaf and 19.22-nm bark). The larvae, pupae and adults of filariasis vector C. quinquefasciatus were found to be more susceptible to our AgNPs than the malaria vector An. stephensi. The first and the second instar larvae of C. quinquefasciatus show a mortality rate of 100% after 30 min of exposure. The results against the pupa of C. quinquefasciatus were recorded as LC?? 4 ppm, LC?? 11 ppm and LC?? 13 ppm after 3 h of exposure. In the case of adult mosquitoes, LC?? 1.06 ?L/cm(2), LC?? 2.13 ?L/cm(2) and LC?? 2.4 ?L/cm(2) were obtained after 4 h of exposure. These results suggest that our AgNPs are environment-friendly for controlling malarial and filarial vectors. PMID:25132567

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

    PubMed

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

    2011-04-01

    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

  15. Risk factors for treatment failure after melarsoprol for Trypanosoma brucei gambiense trypanosomiasis in Uganda

    Microsoft Academic Search

    D. Legros; S. Evans; F. Maiso; J. C. K. Enyaru; D. Mbulamberi

    1999-01-01

    We evaluated the treatment failure rate among late-stage human African trypanosomiasis (HAT) patients treated with melarsoprol in Arua, northern Uganda, between September 1995 and August 1996, and identified the risk factors for treatment failure. We conducted a retrospective cohort study in October 1998, and performed a survival analysis. A treatment failure was defined as a late-stage HAT patient fully treated

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

    Microsoft Academic Search

    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

    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,

  17. Studies on the epidemiology of trypanosomiasis in sheep and goats in Kenya

    Microsoft Academic Search

    L. Griffin; E. W. Allonby

    1979-01-01

    The epidemiology of trypanosomiasis in a tsetse-infested range area of Kenya was studied for 2 years in various breeds of sheep and goats. Observations, including infection rates, PCV, temperature and weight loss indicated that the exotic breeds were more susceptible to natural trypanosomal infection than the indigenous breeds and that the infection may be severely debilitating and in many cases

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

    Microsoft Academic Search

    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

    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

  19. Characterisation of the Wildlife Reservoir Community for Human and Animal Trypanosomiasis in the Luangwa Valley, Zambia

    Microsoft Academic Search

    Neil E. Anderson; Joseph Mubanga; Eric M. Fevre; Kim Picozzi; Mark C. Eisler; Robert Thomas; Susan C. Welburn

    2011-01-01

    BackgroundAnimal and human trypanosomiasis are constraints to both animal and human health in Sub-Saharan Africa, but there is little recent evidence as to how these parasites circulate in wild hosts in natural ecosystems. The Luangwa Valley in Zambia supports high densities of tsetse flies (Glossina species) and is recognised as an historical sleeping sickness focus. The objective of this study

  20. [Rapid risk assessment on the import of American trypanosomiasis to China].

    PubMed

    Qian, Ying-Jun; Li, Shi-Zhu; Wang, Qiang; Zhang, Li; Liu, Wei; Chen, Jia-Xu; Wang, Jun-Yun; Xiao, Ning; Zhou, Xiao-Nong

    2013-02-01

    American trypanosomiasis, as one of the "neglected tropical diseases", is a zoonosis induced by Trypanosoma cruzi. It is endemic in 18 countries in the Central and South America, especially in rural areas. A rapid risk assessment was carried out to analyze the potential threat of imported cases to China, which would provide information to policy makers in health authorities. PMID:24812840

  1. 1066 IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 51, NO. 5, OCTOBER 2004 Stator-Flux-Oriented Vector Control of Synchronous

    E-print Network

    Hofmann, Heath F.

    -mentioned advantages is a motor/generator for a flywheel energy storage system [4]. Vector control of synchronous on the Internet July 15, 2004. This paper was presented at the 20th International Telecommunications Energy

  2. Robust Hotelling T2 control chart using reweighted minimum vector variance estimators

    NASA Astrophysics Data System (ADS)

    Ali, Hazlina; Yahaya, Sharipah Soaad Syed; Omar, Zurni

    2014-12-01

    Hotelling T2 control chart is employed to monitor the stability of a multivariate process in Phase I and II. Traditional Hotelling T2 control chart using classical estimators in Phase I, however, suffers from masking and swamping effects and thus jeorpadizes its performance. To alleviate this problem, robust location and scale estimators are recommended instead. In this paper, a new Hotelling T2 control chart based on highly robust and efficient estimators of location and scatter estimators, known as reweighted minimum vector variance estimators, is proposed. Numerical results show that the new chart is not only capable of detecting outliers but it can also control the alarm rates better than the existing charts.

  3. A Gyroless Safehold Control Law Using Angular Momentum as an Inertial Reference Vector

    NASA Technical Reports Server (NTRS)

    Stoneking, Eric; Lebsock, Ken

    2008-01-01

    A novel safehold control law was developed for the nadir-pointing Vegetation Canopy Lidar (VCL) spacecraft, necessitated by a challenging combination of constraints. The instrument optics did not have a recloseable cover to protect them form potentially catastrophic damage if they were exposed to direct sunlight. The baseline safehold control law relied on a single-string inertial reference unit. A gyroless safehold law was developed to give a degree of robustness to gyro failures. Typical safehold solutions were not viable; thermal constraints made spin stabilization unsuitable, and an inertial hold based solely on magnetometer measurements wandered unaceptably during eclipse. The novel approach presented here maintains a momentum bias vector not for gyroscopic stiffness, but to use as an inertial reference direction during eclipse. The control law design is presented. The effect on stability of the rank-deficiency of magnetometer-based rate derivation is assessed. The control law's performance is evaluated by simulation.

  4. A Gyroless Safehold Control Law using Angular Momentum as an Inertial Reference Vector

    NASA Technical Reports Server (NTRS)

    Stoneking, Eric; Lebsock, Ken

    2008-01-01

    A novel safehold control law was developed for the nadir-pointing Vegetation Canopy Lidar (VCL) spacecraft, necessitated by a challenging combination of constraints. The instrument optics did not have a reclosable cover to protect them from potentially catastrophic damage if they were exposed to direct sunlight. The baseline safehold control law relied on a single-string inertial reference unit. A gyroless safehold law was developed to give a degree of rebustness to gyro failures. Typical safehold solutions were not viable; thermal constraints made spin stabilization unsuitable, and an inertial hold based solely on magnetometer measurements wandered unacceptably during eclipse. The novel approach presented here maintains a momentum bias vector not for gyroscopic stiffness, but to use as an inertial reference direction during eclipse. The control law design is presented. The effect on stability of the rate-deficiency of magnetometer-based rate derivation is assessed. The control law's performance is evaluated by simulation.

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

    Microsoft Academic Search

    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

    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

  6. Further analysis of singular vector and ENSO predictability in the Lamont model--Part I: singular vector and the control

    E-print Network

    Tang, Youmin

    and decades; while singular values exhibit a strong sensitivity to initial conditions. The dynamical diagnosis perturbation growth, and that the linear optimal perturbation is more than twice as large as the nonlinear oneFurther analysis of singular vector and ENSO predictability in the Lamont model--Part I: singular

  7. Review of the Minimus Complex of Anopheles, main malaria vector in Southeast Asia: from taxonomic issues to vector control strategies

    Microsoft Academic Search

    C. Garros; W. Van Bortel; H. D. Trung; M. Coosemans; S. Manguin

    2006-01-01

    Summary background The Minimus Complex of Anopheles subgenus Cellia is composed of two sibling species, A and C, on the Southeast Asian mainland, and a third allopatric species E that occurs in the Ryukyu Archipelago (Japan), a malaria-free region. Anopheles minimus s.l. is considered to be one of the main malaria vector in the hilly forested regions of Southeast Asia.

  8. Application of a compound controller based on fuzzy control and support vector machine to ship's boiler-turbine coordinated control system

    NASA Astrophysics Data System (ADS)

    Liu, Sheng; Li, Yan-Yan

    2009-03-01

    Multivariables, strong coupling, nonlinearity, and large delays characterize the boiler-turbine coordinated control systems for ship power equipment. To better deal with these conditions, a compound control strategy based on a support vector machine (SVM) with inverse identification was proposed and applied to research simulating coordinated control systems. This method combines SVM inverse control and fuzzy control, taking advantage of the merits of SVM inverse controls which can be designed easily and have high reliability, and those of fuzzy controls, which respond rapidly and have good anti-jamming capability and robustness. It ensures the controller can be controlled with near instantaneous adjustments to maintain a steady state, even if the SVM is not trained well. The simulation results show that the control quality of this fuzzy-SVM compound control algorithm is high, with good performance in dynamic response speed, static stability, restraint of overshoot, and robustness.

  9. Online search based fuzzy optimum efficiency operation in steady and transient states for DC and AC vector controlled motors

    Microsoft Academic Search

    E. S. Sergaki; G. S. Stavrakakis

    2008-01-01

    This paper presents an efficiency optimization control system which can be incorporated as an outer loop to a standard indirect vector speed control system for both AC and DC motor drives (i.e. Induction motor, Permanent Magnet Synchronous motor, Synchronous Reluctance motor and DC motor drives), when not operating at full load. The proposed control system adjusts the air-gap current space

  10. Advances in biological control in relation to vectors of human diseases

    PubMed Central

    Weiser, J.

    1963-01-01

    In recent years, increased knowledge of insect pathology and ecology and the development of insecticide-resistance have led to a revival of interest in biological methods of controlling insects that carry human diseases. The author of this paper reviews the information at present available with regard to the various pathogens, predators and parasites of insect vectors of human disease—cockroaches, lice, bugs, fleas, mosquitos, flies and ticks—and suggests lines of future research that might prove profitable. In this connexion he stresses that only a world-wide investigation of the diseases of medically important insects will yield data on which a balanced biological research programme can be based—a programme leading to the development of practicable control procedures and their integration with chemical and other methods of control. PMID:20604158

  11. Lentiviral vector system for coordinated constitutive and drug controlled tetracycline-regulated gene co-expression.

    PubMed

    Stahlhut, Maike; Schwarzer, Adrian; Eder, Matthias; Yang, Min; Li, Zhixiong; Morgan, Michael; Schambach, Axel; Kustikova, Olga S

    2015-09-01

    Constitutive co-expression of cooperating transgenes using retroviral integrating vectors is frequently used for genetic modification of different cell types to establish therapeutic or cancer models. However, such approaches are unable to dissect the influence of dose, order and reversibility of transgene expression on the fate of newly developed therapeutic/malignant phenotypes. We present a modular lentiviral vector system, which provides expression of constitutive and inducible components. To demonstrate its functionality, we constitutively expressed the well-described transcription factor Meis1 followed by inducible co-expression of collaborating partner Hoxa9 under the control of tetracycline responsive promoters in murine fibroblasts and primary hematopoietic progenitor cells (HPCs). Fluorescent markers to track transgene co-expression revealed tightly controlled, efficiently inducible and reversible but cell type dependent gene transfer over time. We demonstrated dose-dependent blockade of myeloid differentiation when both Meis1/Hoxa9 were concomitantly overexpressed in primary HPCs in vitro, but the absence of the transformed phenotype in non-induced samples or when Hoxa9 expression was down-regulated. This system combines the advantages of lentiviral gene transfer and the opportunity for drug-controlled co-expression of multiple transgenes to dissect, among others, gene networks governing complex cell behavior, such as proto-oncogene dose-dependent leukemogenic pathways or collaborating mechanisms of genes enhancing competitive fitness of hematopoietic cells. PMID:26113075

  12. Robust Linear-Parameter Varying Autopilot Design for a Tail\\/Thrust Vector Controlled Missile

    Microsoft Academic Search

    Berno J. E. Misgeld; Marco Darcis; Thomas Kuhn

    \\u000a A robust autopilot design methodology using linear parameter varying transformations is presented and applied to a high-agile\\u000a surface launched air defence missile, which is currently developed by Diehl-BGT-Defence. The lateral dynamics of the tail\\/thrust\\u000a vector controlled missile are modelled as a second-order quasi-linear parameter varying (LPV) system. The incidence angle\\u000a is used as exogenous variable, which is assumed to be

  13. Estimating off-nominal performance of a solid rocket motor for thrust vector control guidance

    NASA Astrophysics Data System (ADS)

    Schmidt, Garfield C.

    1992-08-01

    There are two main parameters relating the off-nominal performance of a solid rocket motor to its nominal performance. One parameter is associated with specific impulse and the other with burn rate. The way in which these parameters can be used to predict off-nominal acceleration from the nominal is reviewed, and a filter for estimating these parameters using accelerometer output and stored tables of nominal performance is derived. A closed-form solution is then derived for the thrust angle required of a thrust-vector-controlled rocket in order to intercept a constant velocity target.

  14. The development of H-II rocket solid rocket booster thrust vector control system

    NASA Astrophysics Data System (ADS)

    Nagai, Hirokazu; Fukushima, Yukio; Kazama, Hiroo; Asai, Tatsuro; Okaya, Shunichi; Watanabe, Yasushi; Muramatsu, Shoji

    The development of the thrust-vector-control (TVC) system for the two solid rocket boosters (SRBs) of the H-II rocket, which was started in 1984 and completed in 1989, is described. Special attention is given to the system's design, the trade-off studies, and the evaluation of the SRB-TVC system performance, as well as to problems that occurred in the course of the system's development and to the countermeasures that were taken. Schematic diagrams are presented for the H-II rocket, the SRB, and the SRB-TVC system configurations.

  15. Effect of dengue vector control interventions on entomological parameters in developing countries: a systematic review and meta-analysis.

    PubMed

    Erlanger, T E; Keiser, J; Utzinger, J

    2008-09-01

    The aim of this review was to compare the effects of different dengue vector control interventions (i.e. biological control, chemical control, environmental management and integrated vector management) with respect to the following entomological parameters: Breteau index (BI), container index (CI), and house index (HI). We systematically searched PubMed, ISI Web of Science, Science Direct, the Dengue Bulletin of the World Health Organization and reference lists of retrieved articles on dengue vector control interventions in developing countries. We extracted data on the effectiveness of different dengue vector control interventions (defined as the relative reduction of an entomological measure caused by the intervention compared with the control or pre-intervention phase) and calculated a measure of combined relative effectiveness, with 95% confidence intervals (95% c.i.). We identified 56 publications covering 61 dengue vector control interventions. Integrated vector management was found to be the most effective method to reduce the CI, HI and BI, resulting in random combined relative effectiveness values of 0.12 (95% c.i. 0.02-0.62), 0.17 (95% c.i. 0.02-1.28) and 0.33 (95% c.i. 0.22-0.48), respectively. Environmental management showed a relatively low effectiveness of 0.71 (95% c.i. 0.55-0.90) for the BI, 0.49 (95% c.i. 0.30-0.79) for the CI and 0.43 (95% c.i. 0.31-0.59) for the HI. Biological control (relative effectiveness for the CI: 0.18) usually targeted a small number of people (median population size: 200; range 20-2500), whereas integrated vector management focused on larger populations (median: 12 450; range: 210-9 600 000). In conclusion, dengue vector control is effective in reducing vector populations, particularly when interventions use a community-based, integrated approach, which is tailored to local eco-epidemiological and sociocultural settings and combined with educational programmes to increase knowledge and understanding of best practice. New research should assess the density-dependent effectiveness of each control measure in order to estimate whether reducing vector numbers has an impact on dengue transmission when populations are at a critical threshold. PMID:18816269

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

    PubMed Central

    2011-01-01

    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. PMID:21798055

  17. Lyapunov Vector Fields for Autonomous UAV Flight Control1 Dale A. Lawrence2

    E-print Network

    Frew, Eric W.

    , 80309 Abstract General techniques for constructing vector fields for UAV guidance are provided. Nomenclature r = UAV position vector relative to an inertial reference frame ( )z,y,x = Inertial frame plane )r( = Vector field normalizer = Relative circulation vs. contraction weighting factor = Vector

  18. Comparison of Vector Competence of Aedes mediovittatus and Aedes aegypti for Dengue Virus: Implications for Dengue Control in the Caribbean

    PubMed Central

    Poole-Smith, B. Katherine; Hemme, Ryan R.; Delorey, Mark; Felix, Gilberto; Gonzalez, Andrea L.; Amador, Manuel; Hunsperger, Elizabeth A.; Barrera, Roberto

    2015-01-01

    Background Aedes mediovittatus mosquitoes are found throughout the Greater Antilles in the Caribbean and often share the same larval habitats with Ae. Aegypti, the primary vector for dengue virus (DENV). Implementation of vector control measures to control dengue that specifically target Ae. Aegypti may not control DENV transmission in Puerto Rico (PR). Even if Ae. Aegypti is eliminated or DENV refractory mosquitoes are released, DENV transmission may not cease when other competent mosquito species like Ae. Mediovittatus are present. To compare vector competence of Ae. Mediovittatus and Ae. Aegypti mosquitoes, we studied relative infection and transmission rates for all four DENV serotypes. Methods To compare the vector competence of Ae. Mediovittatus and Ae. Aegypti, mosquitoes were exposed to DENV 1–4 per os at viral titers of 5–6 logs plaque-forming unit (pfu) equivalents. At 14 days post infectious bloodmeal, viral RNA was extracted and tested by qRT-PCR to determine infection and transmission rates. Infection and transmission rates were analyzed with a generalized linear model assuming a binomial distribution. Results Ae. Aegypti had significantly higher DENV-4 infection and transmission rates than Ae. mediovittatus. Conclusions This study determined that Ae. Mediovittatus is a competent DENV vector. Therefore dengue prevention programs in PR and the Caribbean should consider both Ae. Mediovittatus and Ae. Aegypti mosquitoes in their vector control programs. PMID:25658951

  19. Can vector control play a useful supplementary role against bancroftian filariasis?

    PubMed Central

    Maxwell, C. A.; Mohammed, K.; Kisumku, U.; Curtis, C. F.

    1999-01-01

    A single campaign of mass treatment for bancroftian filariasis with diethylcarbamazine (DEC) in Makunduchi, a town in Zanzibar, United Republic of Tanzania, combined with elimination of mosquito breeding in pit latrines with polystyrene beads was followed by a progressive decline over a 5-year period in the microfilarial rate from 49% to 3%. Evidence that vector control had contributed to this long-term decline was obtained by comparison with another town, Moga, where a DEC campaign was used without vector control and where resurgence of microfilariae could be observed 3-6 years after the campaign. In Zanzibar town, treatment of 3844 wet pit latrines and cesspits with polystyrene beads reduced the adult mosquito population in houses by about 65%. Supplementary treatment of open drains and marshes with Bacillus sphaericus produced little or no additional reduction compared to a sector of the town where only pit treatment with polystyrene was carried out. The cost and effort of achieving the 65% reduction in mosquito population could hardly be justified for its impact on filariasis alone, but its noticeable impact on biting nuisance might help to gain community support for an integrated programme. PMID:10083712

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

    PubMed Central

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

    2013-01-01

    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. PMID:24086399

  1. Regulation of N-myc gene expression: use of an adenovirus vector to demonstrate posttranscriptional control.

    PubMed Central

    Babiss, L E; Friedman, J M

    1990-01-01

    We present evidence that differences in the levels of N-myc mRNA among different cell types are the result of posttranscriptional control. First, we noted that while steady-state mouse N-myc mRNA could be detected only in fetal mouse brain, it was transcribed at an equivalent rate in adult brain, liver, spleen, and placenta and in fetal brain. Similarly, the human N-myc gene was transcribed at an equivalent rate in HeLa cells, which do not accumulate this RNA in the cytoplasm, and cell lines G401 (a Wilms tumor-derived cell line) and SKNMc (established from a primitive neuroepithelioma), which do express N-myc RNA. As expected, the N-myc promoter functioned at equivalent rates, as demonstrated by the level of a reporter gene, when introduced into these cell types by using a recombinant adenovirus vector. The suggestion that posttranscriptional mechanisms control the level of this RNA was supported by the observation that sequences in the N-myc third exon specifically decreased the level of E1A mRNA when these sequences were placed downstream of the E1A promoter in a recombinant adenovirus. Finally, we further localized these sequences to a 600-bp fragment of the third exon by introducing various subclones of this sequence downstream of the E1A promoter in both viral and plasmid vectors. Images PMID:2147226

  2. Regulation of N-myc gene expression: use of an adenovirus vector to demonstrate posttranscriptional control.

    PubMed

    Babiss, L E; Friedman, J M

    1990-12-01

    We present evidence that differences in the levels of N-myc mRNA among different cell types are the result of posttranscriptional control. First, we noted that while steady-state mouse N-myc mRNA could be detected only in fetal mouse brain, it was transcribed at an equivalent rate in adult brain, liver, spleen, and placenta and in fetal brain. Similarly, the human N-myc gene was transcribed at an equivalent rate in HeLa cells, which do not accumulate this RNA in the cytoplasm, and cell lines G401 (a Wilms tumor-derived cell line) and SKNMc (established from a primitive neuroepithelioma), which do express N-myc RNA. As expected, the N-myc promoter functioned at equivalent rates, as demonstrated by the level of a reporter gene, when introduced into these cell types by using a recombinant adenovirus vector. The suggestion that posttranscriptional mechanisms control the level of this RNA was supported by the observation that sequences in the N-myc third exon specifically decreased the level of E1A mRNA when these sequences were placed downstream of the E1A promoter in a recombinant adenovirus. Finally, we further localized these sequences to a 600-bp fragment of the third exon by introducing various subclones of this sequence downstream of the E1A promoter in both viral and plasmid vectors. PMID:2147226

  3. Current status of kala-azar and vector control in China.

    PubMed Central

    Guan, L. R.

    1991-01-01

    Kala-azar, which was prevalent in the vast area of China that lies to the north of the Yangtze River from the 1920s to the 1950s, is now effectively under control as a result of strenuous intervention since the founding of the People's Republic of China in 1949. Apart from 15-20 new cases that occur annually in the Keshi plain, Xinjiang Autonomous Region, the achievements of control practised in other former endemic areas in the plains have been significant and consolidated. In the mountainous areas in north-west China, where the vector, Phlebotomus chinensis, is abundant and canine visceral leishmaniasis is common, there are still sporadic cases of kala-azar. Also, in recent years, new infections have often occurred in the deserts of Xinjiang and western Inner Mongolia, although the reservoir of the infection has not been identified. PMID:1959161

  4. Optimization of Control Strategies for Non-Domiciliated Triatoma dimidiata, Chagas Disease Vector in the Yucatán Peninsula, Mexico

    PubMed Central

    Barbu, Corentin; Dumonteil, Eric; Gourbière, Sébastien

    2009-01-01

    Background Chagas disease is the most important vector-borne disease in Latin America. Regional initiatives based on residual insecticide spraying have successfully controlled domiciliated vectors in many regions. Non-domiciliated vectors remain responsible for a significant transmission risk, and their control is now a key challenge for disease control. Methodology/Principal Findings A mathematical model was developed to predict the temporal variations in abundance of non-domiciliated vectors inside houses. Demographic parameters were estimated by fitting the model to two years of field data from the Yucatan peninsula, Mexico. The predictive value of the model was tested on an independent data set before simulations examined the efficacy of control strategies based on residual insecticide spraying, insect screens, and bednets. The model accurately fitted and predicted field data in the absence and presence of insecticide spraying. Pyrethroid spraying was found effective when 50 mg/m2 were applied yearly within a two-month period matching the immigration season. The >80% reduction in bug abundance was not improved by larger doses or more frequent interventions, and it decreased drastically for different timing and lower frequencies of intervention. Alternatively, the use of insect screens consistently reduced bug abundance proportionally to the reduction of the vector immigration rate. Conclusion/Significance Control of non-domiciliated vectors can hardly be achieved by insecticide spraying, because it would require yearly application and an accurate understanding of the temporal pattern of immigration. Insect screens appear to offer an effective and sustainable alternative, which may be part of multi-disease interventions for the integrated control of neglected vector-borne diseases. PMID:19365542

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

    PubMed Central

    2012-01-01

    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. PMID:23146423

  6. Eco-bio-social research on community-based approaches for Chagas disease vector control in Latin America

    PubMed Central

    Gürtler, Ricardo E.; Yadon, Zaida E.

    2015-01-01

    This article provides an overview of three research projects which designed and implemented innovative interventions for Chagas disease vector control in Bolivia, Guatemala and Mexico. The research initiative was based on sound principles of community-based ecosystem management (ecohealth), integrated vector management, and interdisciplinary analysis. The initial situational analysis achieved a better understanding of ecological, biological and social determinants of domestic infestation. The key factors identified included: housing quality; type of peridomestic habitats; presence and abundance of domestic dogs, chickens and synanthropic rodents; proximity to public lights; location in the periphery of the village. In Bolivia, plastering of mud walls with appropriate local materials and regular cleaning of beds and of clothes next to the walls, substantially decreased domestic infestation and abundance of the insect vector Triatoma infestans. The Guatemalan project revealed close links between house infestation by rodents and Triatoma dimidiata, and vector infection with Trypanosoma cruzi. A novel community-operated rodent control program significantly reduced rodent infestation and bug infection. In Mexico, large-scale implementation of window screens translated into promising reductions in domestic infestation. A multi-pronged approach including community mobilisation and empowerment, intersectoral cooperation and adhesion to integrated vector management principles may be the key to sustainable vector and disease control in the affected regions. PMID:25604759

  7. The Atlas of human African trypanosomiasis: a contribution to global mapping of neglected tropical diseases

    PubMed Central

    2010-01-01

    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 met. For this reason WHO launched the HAT Atlas initiative, jointly implemented with the Food and Agriculture Organization of the United Nations, in the framework of the Programme Against African Trypanosomosis. Results The distribution of HAT is presented for 23 out of 25 sub-Saharan countries having reported on the status of sleeping sickness in the period 2000 - 2009. For the two remaining countries, i.e. Angola and the Democratic Republic of the Congo, data processing is ongoing. Reports by National Sleeping Sickness Control Programmes (NSSCPs), Non-Governmental Organizations (NGOs) and Research Institutes were collated and the relevant epidemiological data were entered in a database, thus incorporating (i) the results of active screening of over 2.2 million people, and (ii) cases detected in health care facilities engaged in passive surveillance. A total of over 42 000 cases of HAT and 6 000 different localities were included in the database. Various sources of geographic coordinates were used to locate the villages of epidemiological interest. The resulting average mapping accuracy is estimated at 900 m. Conclusions Full involvement of NSSCPs, NGOs and Research Institutes in building the Atlas of HAT contributes to the efficiency of the mapping process and it assures both the quality of the collated information and the accuracy of the outputs. Although efforts are still needed to reduce the number of undetected and unreported cases, the comprehensive, village-level mapping of HAT control activities over a ten-year period ensures a detailed and reliable representation of the known geographic distribution of the disease. Not only does the Atlas serve research and advocacy, but, more importantly, it provides crucial evidence and a valuable tool for making informed decisions to plan and monitor the control of sleeping sickness. PMID:21040555

  8. 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

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

    2004-01-01

    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

  9. Fuzzy logic based on-line MRAC tuning of slip gain for an indirect vector-controlled induction motor drive

    Microsoft Academic Search

    G. C. D. Sousa; Bimal K. Bose; Kyung S. Kim

    1993-01-01

    Slip gain tuning of indirect vector controlled induction motor drive has been a subject of intense research interest in recent years. The paper proposes the fuzzy logic based online tuning of slip gain using the standard model reference adaptive control (MRAC) technique. MRAC methods based on reactive power and D-axis voltage are combined together with a weighting factor that is

  10. Lower-Cost Sensorless Vector Control Method for Three-Phase PMSMs That Uses One-Shunt Current Detection

    Microsoft Academic Search

    Huangsheng Xu

    2008-01-01

    Sensorless vector control (SVC) of three-phase AC permanent magnetic synchronous motors (PMSMs) was developed years ago and is now being applied in industry. Implementations use hardware to measure two motor phase currents for current control and flux observation, and the sensors required to do this put a lower limit on cost. This paper presents a study and investigation of a

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

    Microsoft Academic Search

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

    2004-01-01

    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

  12. USDA-ARS-CMAVE Pesticide Research for the DoD: A Needs-Based Program for Vector Control

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Despite existing measures to prevent and control arthropod-borne diseases in military units, these diseases continue to be serious threats to deployed troops. Due to a shrinking list of safe, cost-effective pesticides for control of disease vectors, new and improved toxicants and methods for deliver...

  13. Monitoring malaria vector control interventions: effectiveness of five different adult mosquito sampling methods.

    PubMed

    Onyango, Shirley A; Kitron, Uriel; Mungai, Peter; Muchiri, Eric M; Kokwaro, Elizabeth; King, Charles H; Mutuku, Francis M

    2013-09-01

    Long-term success of ongoing malaria control efforts based on mosquito bed nets (long-lasting insecticidal net) and indoor residual spraying is dependent on continuous monitoring of mosquito vectors, and thus on effective mosquito sampling tools. The objective of our study was to identify the most efficient mosquito sampling tool(s) for routine vector surveillance for malaria and lymphatic filariasis transmission in coastal Kenya. We evaluated relative efficacy of five collection methods--light traps associated with a person sleeping under a net, pyrethrum spray catches, Prokopack aspirator, clay pots, and urine-baited traps--in four villages representing three ecological settings along the south coast of Kenya. Of the five methods, light traps were the most efficient for collecting female Anopheles gambiae s.l. (Giles) (Diptera: Culicidae) and Anopheles funestus (Giles) (Diptera: Culicidae) mosquitoes, whereas the Prokopack aspirator was most efficient in collecting Culex quinquefasciatus (Say) (Diptera: Culicidae) and other culicines. With the low vector densities here, and across much of sub-Saharan Africa, wherever malaria interventions, long-lasting insecticidal nets, and/or indoor residual spraying are in place, the use of a single mosquito collection method will not be sufficient to achieve a representative sample of mosquito population structure. Light traps will remain a relevant tool for host-seeking mosquitoes, especially in the absence of human landing catches. For a fair representation of the indoor mosquito population, light traps will have to be supplemented with aspirator use, which has potential for routine monitoring of indoor resting mosquitoes, and can substitute the more labor-intensive and intrusive pyrethrum spray catches. There are still no sufficiently efficient mosquito collection methods for sampling outdoor mosquitoes, particularly those that are bloodfed. PMID:24180120

  14. Monitoring Malaria Vector Control Interventions: Effectiveness of Five Different Adult Mosquito Sampling Methods

    PubMed Central

    Onyango, Shirley A.; Kitron, Uriel; Mungai, Peter; Muchiri, Eric M.; Kokwaro, Elizabeth; King, Charles H.; Mutuku, Francis M.

    2014-01-01

    Long-term success of ongoing malaria control efforts based on mosquito bed nets (long-lasting insecticidal net) and indoor residual spraying is dependent on continuous monitoring of mosquito vectors, and thus on effective mosquito sampling tools. The objective of our study was to identify the most efficient mosquito sampling tool(s) for routine vector surveillance for malaria and lymphatic filariasis transmission in coastal Kenya. We evaluated relative efficacy of five collection methods—light traps associated with a person sleeping under a net, pyrethrum spray catches, Prokopack aspirator, clay pots, and urine-baited traps—in four villages representing three ecological settings along the south coast of Kenya. Of the five methods, light traps were the most efficient for collecting female Anopheles gambiae s.l. (Giles) (Diptera: Culicidae) and Anopheles funestus (Giles) (Diptera: Culicidae) mosquitoes, whereas the Prokopack aspirator was most efficient in collecting Culex quinquefasciatus (Say) (Diptera: Culicidae) and other culicines. With the low vector densities here, and across much of sub-Saharan Africa, wherever malaria interventions, long-lasting insecticidal nets, and/or indoor residual spraying are in place, the use of a single mosquito collection method will not be sufficient to achieve a representative sample of mosquito population structure. Light traps will remain a relevant tool for host-seeking mosquitoes, especially in the absence of human landing catches. For a fair representation of the indoor mosquito population, light traps will have to be supplemented with aspirator use, which has potential for routine monitoring of indoor resting mosquitoes, and can substitute the more labor-intensive and intrusive pyrethrum spray catches. There are still no sufficiently efficient mosquito collection methods for sampling outdoor mosquitoes, particularly those that are bloodfed. PMID:24180120

  15. Genetically Modifying the Insect Gut Microbiota to Control Chagas Disease Vectors through Systemic RNAi

    PubMed Central

    Taracena, Mabel L.; Oliveira, Pedro L.; Almendares, Olivia; Umaña, Claudia; Lowenberger, Carl; Dotson, Ellen M.; Paiva-Silva, Gabriela O.; Pennington, Pamela M.

    2015-01-01

    Technologies based on RNA interference may be used for insect control. Sustainable strategies are needed to control vectors of Chagas disease such as Rhodnius prolixus. The insect microbiota can be modified to deliver molecules to the gut. Here, Escherichia coli HT115(DE3) expressing dsRNA for the Rhodnius heme-binding protein (RHBP) and for catalase (CAT) were fed to nymphs and adult triatomine stages. RHBP is an egg protein and CAT is an antioxidant enzyme expressed in all tissues by all developmental stages. The RNA interference effect was systemic and temporal. Concentrations of E. coli HT115(DE3) above 3.35 × 107 CFU/mL produced a significant RHBP and CAT gene knockdown in nymphs and adults. RHBP expression in the fat body was reduced by 99% three days after feeding, returning to normal levels 10 days after feeding. CAT expression was reduced by 99% and 96% in the ovary and the posterior midgut, respectively, five days after ingestion. Mortality rates increased by 24-30% in first instars fed RHBP and CAT bacteria. Molting rates were reduced by 100% in first instars and 80% in third instars fed bacteria producing RHBP or CAT dsRNA. Oviposition was reduced by 43% (RHBP) and 84% (CAT). Embryogenesis was arrested in 16% (RHBP) and 20% (CAT) of laid eggs. Feeding females 105 CFU/mL of the natural symbiont, Rhodococcus rhodnii, transformed to express RHBP-specific hairpin RNA reduced RHBP expression by 89% and reduced oviposition. Modifying the insect microbiota to induce systemic RNAi in R. prolixus may result in a paratransgenic strategy for sustainable vector control. PMID:25675102

  16. Contrasting Population Structures of Two Vectors of African Trypanosomoses in Burkina Faso: Consequences for Control

    PubMed Central

    Ravel, Sophie; Vreysen, Marc J. B.; Domagni, Kouadjo T.; Causse, Sandrine; Solano, Philippe; de Meeûs, Thierry

    2011-01-01

    Background African animal trypanosomosis is a major obstacle to the development of more efficient and sustainable livestock production systems in West Africa. Riverine tsetse species such as Glossina palpalis gambiensis Vanderplank and Glossina tachinoides Westwood are the major vectors. A wide variety of control tactics is available to manage these vectors, but their removal will in most cases only be sustainable if the control effort is targeting an entire tsetse population within a circumscribed area. Methodology/Principal Findings In the present study, genetic variation at microsatellite DNA loci was used to examine the population structure of G. p. gambiensis and G. tachinoides inhabiting four adjacent river basins in Burkina Faso, i.e. the Mouhoun, the Comoé, the Niger and the Sissili River Basins. Isolation by distance was significant for both species across river basins, and dispersal of G. tachinoides was ?3 times higher than that of G. p. gambiensis. Thus, the data presented indicate that no strong barriers to gene flow exists between riverine tsetse populations in adjacent river basins, especially so for G. tachinoides. Conclusions/Significance Therefore, potential re-invasion of flies from adjacent river basins will have to be prevented by establishing buffer zones between the Mouhoun and the other river basin(s), in the framework of the PATTEC (Pan African Tsetse and Trypanosomosis Eradication Campaign) eradication project that is presently targeting the northern part of the Mouhoun River Basin. We argue that these genetic analyses should always be part of the baseline data collection before any tsetse control project is initiated. PMID:21738812

  17. Genetically modifying the insect gut microbiota to control Chagas disease vectors through systemic RNAi.

    PubMed

    Taracena, Mabel L; Oliveira, Pedro L; Almendares, Olivia; Umaña, Claudia; Lowenberger, Carl; Dotson, Ellen M; Paiva-Silva, Gabriela O; Pennington, Pamela M

    2015-02-01

    Technologies based on RNA interference may be used for insect control. Sustainable strategies are needed to control vectors of Chagas disease such as Rhodnius prolixus. The insect microbiota can be modified to deliver molecules to the gut. Here, Escherichia coli HT115(DE3) expressing dsRNA for the Rhodnius heme-binding protein (RHBP) and for catalase (CAT) were fed to nymphs and adult triatomine stages. RHBP is an egg protein and CAT is an antioxidant enzyme expressed in all tissues by all developmental stages. The RNA interference effect was systemic and temporal. Concentrations of E. coli HT115(DE3) above 3.35 × 10(7) CFU/mL produced a significant RHBP and CAT gene knockdown in nymphs and adults. RHBP expression in the fat body was reduced by 99% three days after feeding, returning to normal levels 10 days after feeding. CAT expression was reduced by 99% and 96% in the ovary and the posterior midgut, respectively, five days after ingestion. Mortality rates increased by 24-30% in first instars fed RHBP and CAT bacteria. Molting rates were reduced by 100% in first instars and 80% in third instars fed bacteria producing RHBP or CAT dsRNA. Oviposition was reduced by 43% (RHBP) and 84% (CAT). Embryogenesis was arrested in 16% (RHBP) and 20% (CAT) of laid eggs. Feeding females 105 CFU/mL of the natural symbiont, Rhodococcus rhodnii, transformed to express RHBP-specific hairpin RNA reduced RHBP expression by 89% and reduced oviposition. Modifying the insect microbiota to induce systemic RNAi in R. prolixus may result in a paratransgenic strategy for sustainable vector control. PMID:25675102

  18. Intrathecal Immune Response Pattern for Improved Diagnosis of Central Nervous System Involvement in Trypanosomiasis

    Microsoft Academic Search

    Veerle Lejon; Hansotto Reiber; Dominique Legros; Norbert Djé; Eddy Magnus; Ingrid Wouters; Philippe Büscher

    2003-01-01

    (95%) marker for inflammation of the brain. We propose to replace the World Health Organization (WHO) criteria (white blood cell count 15 cells\\/mL and presence of trypanosomes in CSF) with a new approach for stage determination in trypanosomiasis: CNS involvement is diagnosed only in patients with 120 cells\\/m Lo r with intrathecal IgM synthesis, independent of the presence of trypanosomes

  19. Major QTLs Control Resistance to Rice Hoja Blanca Virus and Its Vector Tagosodes orizicolus

    PubMed Central

    Romero, Luz E.; Lozano, Ivan; Garavito, Andrea; Carabali, Silvio J.; Triana, Monica; Villareal, Natalia; Reyes, Luis; Duque, Myriam C.; Martinez, César P.; Calvert, Lee; Lorieux, Mathias

    2013-01-01

    Rice hoja blanca (white leaf) disease can cause severe yield losses in rice in the Americas. The disease is caused by the rice hoja blanca virus (RHBV), which is transmitted by the planthopper vector Tagosodes orizicolus. Because classical breeding schemes for this disease rely on expensive, time-consuming screenings, there is a need for alternatives such as marker-aided selection. The varieties Fedearroz 2000 and Fedearroz 50, which are resistant to RHBV and to the feeding damage caused by T. orizicolus, were crossed with the susceptible line WC366 to produce segregating F2:3 populations. The F3 families were scored for their resistance level to RHBV and T. orizicolus. The F2:3 lines of both crosses were genotyped using microsatellite markers. One major QTL on the short arm of chromosome 4 was identified for resistance to RHBV in the two populations. Two major QTL on chromosomes 5 and 7 were identified for resistance to T. orizicolus in the Fd2000 × WC366 and Fd50 × WC366 crosses, respectively. This comparative study using two distinct rice populations allowed for a better understanding of how the resistance to RHBV and its vector are controlled genetically. Simple marker-aided breeding schemes based on QTL information can be designed to improve rice germplasm to reduce losses caused by this important disease. PMID:24240781

  20. Control of finger force vectors with changes in fingertip referent coordinates

    PubMed Central

    Wu, Yen-Hsun; Zatsiorsky, Vladimir M.; Latash, Mark L.

    2013-01-01

    The central hypothesis explored in the experiment is that adjustments of fingertip force vectors during object manipulation could result from a simple scaling rule applied to commands to individual digits. The commands have been associated with referent coordinates of the digit tips. The subjects performed quick lifting movements (over 20 cm in under 0.5 s) of a horizontally oriented handle with different combinations of the external load and torque. The prismatic grasp was used with the four fingers pressing on the bottom of the handle and the thumb acting on its top. Principal component and correlation analyses applied to the normal and tangential force vector components confirmed that the force direction of each digit was kept nearly constant in the object-centered referent frame across the loading conditions and movement phases. The middle and ring fingers showed weaker correlations between the force components as compared to the index and little fingers. The differences were likely related to the different roles of the normal force components in the moment of force production. The neural control of the hand, within the studied task, may be adequately described as a simple rule applied to a handful of parameters, such as the referent digit-tip coordinates. PMID:23394398

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

    PubMed Central

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

    1999-01-01

    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. PMID:10327712

  2. Bovine trypanosomiasis in southern Tanzania: parasitological and serological survey of prevalence.

    PubMed

    Connor, R J; Halliwell, R W

    1987-08-01

    In a survey for bovine trypanosomiasis blood smears from 1,617 cattle at 72 sites were examined. Trypanosomes were found in 93 cattle, representing 16% of the cattle in herds in which trypanosomiasis was confirmed. Of the positive cattle 56% had infections with T. congolense, 17% T. vivax and 2.2% T. brucei. Five cattle had mixed infections and in 18 cattle the species was not identified. Sera from 1,352 cattle were tested using microelisa. Ten out of 16 sites, at which no trypanosomes were found in blood smears and at which trypanocides were in use, had over 15% seropositive cattle compared with five of 19 sites at which trypanocides were not in use. It was concluded that the microelisa was a useful aid to the diagnosis of bovine trypanosomiasis and that there is a need for accurate records of drug use and livestock movements to be kept. The serious risk of drug resistant strains of trypanosomes emerging due to the uncontrolled use of trypanocides is emphasised. PMID:3660451

  3. VECTOR CONTROL, PEST MANAGEMENT, RESISTANCE, REPELLENTS Carbon Dioxide Fumigation for Controlling Bed Bugs

    E-print Network

    Wang, Changlu

    Bed Bugs CHANGLU WANG,1 LIHUA LU¨ ,2 AND MING XU3 J. Med. Entomol. 49(5): 1076Ð1083 (2012); DOI: http for controlling bed bugs, Cimex lectularius L. The effect of bed bug developmental stage, temperature, and CO2 concentration on the minimum time to kill 100% of bed bugs was determined. The minimum CO2 concentration lethal

  4. Targeting arthropod subolesin/akirin for the development of a universal vaccine for control of vector infestations and pathogen transmission.

    PubMed

    de la Fuente, José; Moreno-Cid, Juan A; Canales, Mario; Villar, Margarita; de la Lastra, José M Pérez; Kocan, Katherine M; Galindo, Ruth C; Almazán, Consuelo; Blouin, Edmour F

    2011-09-01

    Diseases caused by arthropod-borne pathogens greatly impact on human and animal health. Recent research has provided evidence that tick protective antigens can be used for development of vaccines with the dual target of controlling arthropod infestations and reducing their vector capacity for pathogens. As reviewed herein, protective antigens such as subolesin/akirin, which are highly conserved across vector species, show promise for use in development of a universal vaccine for the control of arthropod infestations and the reduction of pathogen transmission. However, further research is needed in critical areas towards achieving this goal. PMID:21561715

  5. Testing the concept of virally vectored immunosterilisation for the control of wild rabbit and fox populations in Australia.

    PubMed

    Robinson, A J; Holland, M K

    1995-02-01

    Virally vectored immunosterilisation is a concept whereby a gene encoding an antigen from an animal's reproductive system is inserted into a virus and, during infection, stimulates the formation of antibodies to that antigen such that the animal is rendered infertile. There is good evidence that certain proteins from sperm or egg when introduced parenterally will induce infertility. This paper summarises the work of the Cooperative Research Centre for the Biological Control of Vertebrate Pest Populations and reviews progress toward the isolation of the genes for gamete antigens from rabbits and foxes and their introduction into suitable viral vectors as a means of control of these pests in Australia. PMID:7779038

  6. Iterative reconstruction of volumetric modulated arc radiotherapy plans using control point basis vectors

    NASA Astrophysics Data System (ADS)

    Barbiere, Joseph C.; Kapulsky, Alexander; Ndlovu, Alois

    2014-03-01

    Volumetric Modulated Arc Radiotherapy is an innovative technique currently utilized to efficiently deliver complex treatments. Dose rate, speed of rotation, and field shape are continuously varied as the radiation source rotates about the patient. Patient specific quality assurance is performed to verify that the delivered dose distribution is consistent with the plan formulated in a treatment planning system. The purpose of this work is to present novel methodology using a Gafchromic EBT3 film image of a patient plan in a cylindrical phantom and calculating the delivered MU per control point. Images of two dimensional plan dose matrices and film scans are analyzed using MATLAB with the imaging toolbox. Dose profiles in a ring corresponding to the film position are extracted from the plan matrices for comparison with the corresponding measured film dose. The plan is made up of a series of individual static Control Points. If we consider these Control Points a set of basis vectors, then variations in the plan can be represented as the weighted sum of the basis. The weighing coefficients representing the actual delivered MU can be determined by any available optimization tool, such as downhill simplex or non-linear programming. In essence we reconstruct an image of the delivered dose. Clinical quality assurance is performed with this technique by computing a patient plan with the measured monitor units and standard plan evaluation tools such as Dose Volume Histograms. Testing of the algorithm with known changes in the reference images indicated a correlation coefficient greater than 0.99.

  7. Human antibody response to Anopheles saliva for comparing the efficacy of three malaria vector control methods in Balombo, Angola.

    PubMed

    Brosseau, Laura; Drame, Papa Makhtar; Besnard, Patrick; Toto, Jean-Claude; Foumane, Vincent; Le Mire, Jacques; Mouchet, François; Remoue, Franck; Allan, Richard; Fortes, Filomeno; Carnevale, Pierre; Manguin, Sylvie

    2012-01-01

    Human antibody (Ab) response to Anopheles whole saliva, used as biomarker of Anopheles exposure, was investigated over a period of two years (2008-2009), in children between 2 to 9 years old, before and after the introduction of three different malaria vector control methods; deltamethrin treated long lasting impregnated nets (LLIN) and insecticide treated plastic sheeting (ITPS)--Zero Fly®) (ITPS-ZF), deltamethrin impregnated Durable (Wall) Lining (ITPS-DL--Zerovector®) alone, and indoor residual spraying (IRS) with lambdacyhalothrin alone. These different vector control methods resulted in considerable decreases in all three entomological (82.4%), parasitological (54.8%) and immunological criteria analyzed. The highest reductions in the number of Anopheles collected and number of positive blood smears, respectively 82.1% and 58.3%, were found in Capango and Canjala where LLIN and ITPS-ZF were implemented. The immunological data based on the level of anti-saliva IgG Ab in children of all villages dropped significantly from 2008 to 2009, except in Chissequele. These results indicated that these three vector control methods significantly reduced malaria infections amongst the children studied and IRS significantly reduced the human-Anopheles contact. The number of Anopheles, positive blood smears, and the levels of anti-saliva IgG Ab were most reduced when LLIN and ITPS-ZF were used in combination, compared to the use of one vector control method alone, either ITPS-DL or IRS. Therefore, as a combination of two vector control methods is significantly more effective than one control method only, this control strategy should be further developed at a more global scale. PMID:23028499

  8. NATIONAL PROGRESS IN DENGUE VECTOR CONTROL IN VIETNAM: SURVEY FOR MESOCYCLOPS(COPEPODA), MICRONECTA(CORIXIDAE), AND FISH AS BIOLOGICAL CONTROL AGENTS

    Microsoft Academic Search

    VU SINH NAM; NGUYEN THI YEN; MARIA HOLYNSKA; JANET W. REID; BRIAN H. KAY

    This paper describes the process of expanding a successful dengue control program in 3 provinces in northern Vietnam into a national one and demonstrates the presence of a rich, low-cost resource that could have similar applicability to other countries in the region. The cornerstone of the preventive strategy is larval control of Aedes aegypti (L.), the major vector, using predators

  9. Follow-up of Card Agglutination Trypanosomiasis Test (CATT) positive but apparently aparasitaemic individuals in Cote d'Ivoire: evidence for a complex and heterogeneous population

    Microsoft Academic Search

    Andre Garcia; Vincent Jamonneau; Eddy Magnus; Claude Laveissiere; Veerle Lejon; Paul N'guessan; Louis N'dri; Nestor Van Meirvenne; Philippe Buscher

    2000-01-01

    Summary The aetiological diagnosis of human African trypanosomiasis (HAT) is based on the detection of the para- site, but currently available parasitological tests have low sensitivity and are hampered by fluctuating para- sitaemia. The identification of seropositive individuals on whom to focus parasitological examination is based on antibody detection by means of the Card Agglutination Trypanosomiasis Test (CATT\\/T.b.gambi- ense). A

  10. Severity of Human African Trypanosomiasis in East Africa Is Associated with Geographic Location, Parasite Genotype, and Host Inflammatory Cytokine Response Profile

    Microsoft Academic Search

    Lorna MacLean; John E. Chisi; Martin Odiit; Wendy C. Gibson; Vanessa Ferris; Kim Picozzi; Jeremy M. Sternberg

    2004-01-01

    The mechanisms underlying virulence in human African trypanosomiasis are poorly understood, although studies with experimental mice suggest that unregulated host inflammatory responses are associated with disease severity. We identified two trypanosomiasis foci with dramatically different disease virulence profiles. In Uganda, infections followed an acute profile with rapid progression to the late stage (meningoencephalitic infection) in the majority of patients (86.8%).

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

    NASA Astrophysics Data System (ADS)

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

    2006-06-01

    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.

  12. Construction and characterization of nisin-controlled expression vectors for use in Lactobacillus reuteri.

    PubMed

    Wu, Chi-Ming; Lin, Chuen-Fu; Chang, Yi-Chih; Chung, Tung-Ching

    2006-04-01

    The Nisin-controlled gene expression (NICE) system, which was discovered in Lactococcus lactis, was adapted to Lactobacillus reuteri by ligating nisA promoter (PnisA) and nisRK DNA fragments into the Escherichia coli-Lb. reuteri shuttle vector pSTE32. This chimerical plasmid (pNICE) was capable of expressing the heterologous amylase gene (amyL) under nisin induction. Optimization of induction factors for this Lb. reuteri/pNICE system, including nisin concentration (viz. 50 ng/ml), growth phase of culture at which nisin be added (viz. at the early exponential phase), and the best time for analyzing the gene product after inoculation (viz. at the 3rd h), allowed the amylase product to be expressed in high amounts, constituting up to about 18% of the total intracellular protein. Furthermore, the signal peptide (SP) of amyL gene (SPamyL) from Bacillus licheniformis was ligated to the downstream of PnisA in pNICE, upgrading this vector to a NICE-secretion (NIES) level, which was then designated pNIES (Sec+, secretion positive). Characterization of pNIES using an amyL-SPDelta gene (amyL gene lacking its SP) as a reporter revealed the 3rd h after induction as the secretion peak of this system, at which the secretion efficiency and the amount of alpha-amylase being secreted into the culture supernatant were estimated to reach 77.6% and 27.75 mg/l. Expression and secretion of AmyL products by pNIES in Lb. reuteri was also confirmed by SDS-PAGE and immunoblotting analysis. PMID:16636439

  13. Influence of stimuli colour in SSVEP-based BCI wheelchair control using support vector machines.

    PubMed

    Singla, Rajesh; Khosla, Arun; Jha, Rameshwar

    2014-04-01

    This study aims to develop a Steady State Visual Evoked Potential (SSVEP)-based Brain Computer Interface (BCI) system to control a wheelchair, with improving accuracy as the major goal. The developed wheelchair can move in forward, backward, left, right and stop positions. Four different flickering frequencies in the low frequency region were used to elicit the SSVEPs and were displayed on a Liquid Crystal Display (LCD) monitor using LabVIEW. Four colours (green, red, blue and violet) were included in the study to investigate the colour influence in SSVEPs. The Electroencephalogram (EEG) signals recorded from the occipital region were first segmented into 1?s windows and features were extracted by using Fast Fourier Transform (FFT). Three different classifiers, two based on Artificial Neural Network (ANN) and one based on Support Vector Machine (SVM), were compared to yield better accuracy. Twenty subjects participated in the experiment and the accuracy was calculated by considering the number of correct detections produced while performing a pre-defined movement sequence. SSVEP with violet colour showed higher performance than green and red. The One-Against-All (OAA) based multi-class SVM classifier showed better accuracy than the ANN classifiers. The classification accuracy over 20 subjects varies between 75-100%, while information transfer rates (ITR) varies from 12.13-27 bpm for BCI wheelchair control with SSVEPs elicited by violet colour stimuli and classified using OAA-SVM. PMID:24533888

  14. Spray characterization of ultra-low-volume sprayers typically used in vector control.

    PubMed

    Hoffmann, W Clint; Walker, Todd W; Fritz, Bradley K; Farooq, Muhammad; Smith, Vincent L; Robinson, Cathy A; Szumlas, Dan; Lan, Yubin

    2009-09-01

    Numerous spray machines are used to apply pesticides for the control of human disease vectors, such as mosquitoes and flies, and the selection and setup of these machines significantly affects the level of control achieved during an application. The droplet spectra produced by 9 different ultra-low-volume sprayers with oil- and water-based spray solutions were evaluated along with 2 thermal foggers with the use of diesel-based spray solutions. The droplet spectra from the sprayers were measured with the use of laser diffraction droplet sizing equipment. The volume median diameter from the sprayers ranged from 14.8 to 61.9 microm for the oil-based spray solutions and 15.5 to 87.5 microm for the water-based spray solutions. The 2 thermal foggers generated sprays with a volume median diameter of 3.5 microm. The data presented will allow spray applicators to select the spray solution and sprayer that generate the droplet-size spectra that meet the desired specific spray application scenarios. PMID:19852224

  15. Pneumatic motor powered Thrust Vector Control (TVC) for liquid propelled launch vehicles

    NASA Astrophysics Data System (ADS)

    Malone, Mark C.; Evans, P. S.

    1992-02-01

    Recent studies performed for the Titan 4 launch vehicle indicate significant potential advantages in replacing the current stage 1 and 2 recirculating hydraulic TVC (thrust vector control) system with a PMA (pneumatic mechanical actuation) system. Some of the advantages of a PMA system over the recirculating hydraulic system include reduced part count and weight, reduced maintenance and life-cycle cost, and improved mission reliability. PMA technology, used in aircraft applications since the 1960s, is well suited in launch vehicle TVC applications where an existing pneumatic pressure source is available. A typical pneumatic motor TVC consists of a pneumatic power source, a dual rotor pneumatic motor, a gear box, a ball screw actuator, and the associated closed-loop servo-control elements. One key issue with implementing this mechanical approach is designing a TVC system to withstand large load transient disturbances during liquid engine starting. Hydraulic actuator transient loads have exceeded 60,000 lb(sub f) for a 30,000 lb(sub f) stall design actuator during ground starts of the Titan 3B, Stage 1 engine. A PMA TVC system must also withstand these start transients without imparting excessive reaction loads to the engine nozzle and thrust structure. Work completed to date with Martin Marietta to examine pneumatic motor powered TVC options and technology benefits is presented. The load transient issue is discussed along with potential solutions and the associated trades. General background on PMA technology and experience base is also presented.

  16. Sustainable vector control and management of Chagas disease in the Gran Chaco, Argentina

    PubMed Central

    Gürtler, Ricardo E.; Kitron, Uriel; Cecere, M. Carla; Segura, Elsa L.; Cohen, Joel E.

    2007-01-01

    Chagas disease remains a serious obstacle to health and economic development in Latin America, especially for the rural poor. We report the long-term effects of interventions in rural villages in northern Argentina during 1984–2006. Two community-wide campaigns of residual insecticide spraying immediately and strongly reduced domestic infestation and infection with Trypanosoma cruzi in Triatoma infestans bugs and dogs and more gradually reduced the seroprevalence of children <15 years of age. Because no effective surveillance and control actions followed the first campaign in 1985, transmission resurged in 2–3 years. Renewed interventions in 1992 followed by sustained, supervised, community-based vector control largely suppressed the reestablishment of domestic bug colonies and finally led to the interruption of local human T. cruzi transmission. Human incidence of infection was nearly an order of magnitude higher in peripheral rural areas under pulsed, unsupervised, community-based interventions, where human transmission became apparent in 2000. The sustained, supervised, community-based strategy nearly interrupted domestic transmission to dogs but did not eliminate T. infestans despite the absence of pyrethroid-insecticide resistance. T. infestans persisted in part because of the lack of major changes in housing construction and quality. Sustained community participation grew out of establishing a trusted relationship with the affected communities and the local schools. The process included health promotion and community mobilization, motivation, and supervision in close cooperation with locally nominated leaders. PMID:17913895

  17. Development and assessment of plant-based synthetic odor baits for surveillance and control of Malaria vectors

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recent malaria vector control measures have considerably reduced indoor biting mosquito populations. However, reducing the outdoor biting populations remains a challenge because of the unavailability of appropriate lures to achieve this. This study sought to test the efficacy of plant-based syntheti...

  18. DSP based direct torque control of permanent magnet synchronous motor (PMSM) using space vector modulation (DTC-SVM)

    Microsoft Academic Search

    D. Swierczynski; M. P. Kazmierkowski; F. Blaabjerg

    2002-01-01

    This paper presents digital signal processor (DSP) based direct torque control scheme using space vector modulation (DTC-SVM) for permanent magnet synchronous motor (PMSM) drives. The analysis of PMSM shows that the increase of electromagnetic torque is proportional to the increase of the angle between the stator and rotor flux linkages and therefore fast torque response can be obtained by increasing

  19. Direct torque control of permanent magnet synchronous motor (PMSM) using space vector modulation (DTC-SVM)-simulation and experimental results

    Microsoft Academic Search

    D. Swierczynski; M. P. Kazmierkowski

    2002-01-01

    This paper presents digital signal processor (DSP) based direct torque control scheme using space vector modulation (DTC-SVM) for permanent magnet synchronous motor (PMSM) drives. The analysis of PMSM shows that the increase of electromagnetic torque is proportional to the increase of the angle between the stator and rotor flux linkages and therefore fast torque response can be obtained by increasing

  20. Unreliable pesticide control of the vector psyllid Diaphorina citri (Hemiptera: Psyllidae) for the reduction of microorganism disease transmission

    Microsoft Academic Search

    Katsuya Ichinose; Kastuhiko Miyazi; Kunihiko Matsuhira; Keiji Yasuda; Yasutsune Sadoyama; Do Hong Tuan; Doan Van Bang

    2010-01-01

    Systemic insecticides and application methods were examined for the control of the vector psyllid of citrus greening disease, Diaphorina citri, on grown king mandarin trees in an orchard in southern Vietnam from May 2007 to September 2008. Leaf spraying of imidacloprid, thiamethoxam, and clothianidin attained about 50 % to 70 % mortality of the psyllid for one month after the application and

  1. Honey Bees (Hymenoptera: Apidae) as Vectors of Bacillus thuringiensis for Control of Banded Sunflower Moth (Lepidoptera: Tortricidae)

    Microsoft Academic Search

    JAWAHAR L. JYOTI; GARY J. BREWER

    1999-01-01

    A study was conducted in 1996 and 1997 to determine if honey bees, Apis mellifera L., could vector Bacillus thuringiensis Berliner variety kurstaki from hives equipped with a pathogen applicator to sunflower capitula and if the amount of B. thuringiensis deposited on the capitula would be sufficient to control the banded sunflower moth, Cochylis hospes Walsingham. The study dem- onstrated

  2. Design and development of the quad redundant servoactuator for the space shuttle solid rocket booster thrust vector control

    NASA Technical Reports Server (NTRS)

    Lominick, J. M.

    1980-01-01

    The design and theory of operation of the servoactuator used for thrust vector control of the space shuttle solid rocket booster is described accompanied by highlights from the development and qualification test programs. Specific details are presented concerning major anomalies that occurred during the test programs and the corrective courses of action pursued.

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

    Microsoft Academic Search

    Joachim Holtz; Juntao Quan

    2002-01-01

    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.

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

    Microsoft Academic Search

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

    2004-01-01

    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

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

    Microsoft Academic Search

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

    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

  6. Automatic Offset Calibration of Quadrature Encoder Pulse Sensor for Vector Controlled Drive of Permanent Magnet Synchronous Motors

    Microsoft Academic Search

    Mongkol Konghirun

    2005-01-01

    Quadrature encoder pulse (QEP) sensor has been widely used to detect the rotor position of permanent magnet synchronous motors (PMSMs) in the vector controlled drive systems. However, the information regarding to the angular difference between the index signal and the back emfs of motor (so called the index offset) is sometimes lacked in the manufacturers' datasheets. As a result, by

  7. Performance Improvement of IPMSM Position Sensorless Vector Control System by the Online Identification of Stator Resistance and Permanent Magnet Flux

    Microsoft Academic Search

    Tetsuya Fukumoto; Shigenori Togashi; Yoichi Hayashi

    2009-01-01

    Some of the position sensorless vector control methods of IPMSM use the back electromotive force and require accurate values of motor parameter. Their stability is influenced by motor parameter errors. Particularly, it becomes a problem in the case of extreme temperature variation and operation at low speed. In this paper, the online identification of stator resistance and permanent magnet flux

  8. Feasibility of both vector control and displacement factor correction by voltage source type AC-AC matrix converter

    Microsoft Academic Search

    Mehrdad Kazerani; Boon-Teck Ooi

    1995-01-01

    This paper shows that by transforming both sides of the matrix converter to the d-q-o frames of their respective frequencies, there is significant simplification in the transformation matrix which enables the network of one side to be integrated to the other. Thus, it is possible to design for operation with field vector control on the motor side and unity displacement

  9. Improved sensorless vector control for induction motor drives fed by a matrix converter using nonlinear modeling and disturbance observer

    Microsoft Academic Search

    Kyo-Beum Lee; Frede Blaabjerg

    2006-01-01

    This paper presents a new sensorless vector control system for high performance induction motor drives fed by a matrix converter with nonlinearity compensation and disturbance observer. The nonlinear voltage distortion that is caused by commutation delay and on-state voltage drop in switching device is corrected by a new matrix converter modeling. The lumped disturbances such as parameter variation and load

  10. Linear Test Bed. Volume 2: Test Bed No. 2. [linear aerospike test bed for thrust vector control

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Test bed No. 2 consists of 10 combustors welded in banks of 5 to 2 symmetrical tubular nozzle assemblies, an upper stationary thrust frame, a lower thrust frame which can be hinged, a power package, a triaxial combustion wave ignition system, a pneumatic control system, pneumatically actuated propellant valves, a purge and drain system, and an electrical control system. The power package consists of the Mark 29-F fuel turbopump, the Mark 29-0 oxidizer turbopump, a gas generator assembly, and propellant ducting. The system, designated as a linear aerospike system, was designed to demonstrate the feasibility of the concept and to explore technology related to thrust vector control, thrust vector optimization, improved sequencing and control, and advanced ignition systems. The propellants are liquid oxygen/liquid hydrogen. The system was designed to operate at 1200-psia chamber pressure at an engine mixture ratio of 5.5. With 10 combustors, the sea level thrust is 95,000 pounds.

  11. Simon J. Foote is the Joint Head of the

    E-print Network

    Steve Kemp

    at the International Livestock Research Institute, Nairobi, Kenya. Keywords: trypanosomiasis trypanosomosis, malaria-mail: Simon.Foote@utas.edu.au Controlling malaria and African trypanosomiasis: The role of the mouse Simon J and trypanosomiasis are vector-borne protozoal diseases which disproportionately affect the poor. Both give rise

  12. Community mobilization and household level waste management for dengue vector control in Gampaha district of Sri Lanka; an intervention study

    PubMed Central

    Abeyewickreme, W; Wickremasinghe, A R; Karunatilake, K; Sommerfeld, Johannes; Kroeger, Axel

    2012-01-01

    Introduction Waste management through community mobilization to reduce breeding places at household level could be an effective and sustainable dengue vector control strategy in areas where vector breeding takes place in small discarded water containers. The objective of this study was to assess the validity of this assumption. Methods An intervention study was conducted from February 2009 to February 2010 in the populous Gampaha District of Sri Lanka. Eight neighborhoods (clusters) with roughly 200 houses each were selected randomly from high and low dengue endemic areas; 4 of them were allocated to the intervention arm (2 in the high and 2 in the low endemicity areas) and in the same way 4 clusters to the control arm. A baseline household survey was conducted and entomological and sociological surveys were carried out simultaneously at baseline, at 3 months, at 9 months and at 15 months after the start of the intervention. The intervention programme in the treatment clusters consisted of building partnerships of local stakeholders, waste management at household level, the promotion of composting biodegradable household waste, raising awareness on the importance of solid waste management in dengue control and improving garbage collection with the assistance of local government authorities. Results The intervention and control clusters were very similar and there were no significant differences in pupal and larval indices of Aedes mosquitoes. The establishment of partnerships among local authorities was well accepted and sustainable; the involvement of communities and households was successful. Waste management with the elimination of the most productive water container types (bowls, tins, bottles) led to a significant reduction of pupal indices as a proxy for adult vector densities. Conclusion The coordination of local authorities along with increased household responsibility for targeted vector interventions (in our case solid waste management due to the type of preferred vector breeding places) is vital for effective and sustained dengue control. PMID:23318240

  13. Combining Vector Control and User Interface\\/Machine Functions into a Single Microcontroller for White Goods Applications

    Microsoft Academic Search

    Yashvant Jani

    2007-01-01

    In many white goods applications, high-performance vector speed control is implemented in a standalone microcontroller (MCU) while user-interface and machine-control functions are implemented in a second microcontroller. This paper introduces SuperH RISC 32-bit microcontrollers from Renesas Technology that are specifically designed to combine all functions into one MCU, thereby reducing system cost and achieving product-development advantages. We begin by defining

  14. Control strategies for enhanced power smoothing in wind energy systems using a flywheel driven by a vector-controlled induction machine

    Microsoft Academic Search

    Roberto Cárdenas; Rubén Peña; Greg Asher; Jon Clare

    2001-01-01

    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 is

  15. Adenoviral and adeno-associated viral vectors-mediated neuronal gene transfer to cardiovascular control regions of the rat brain.

    PubMed

    Zhang, Yanling; Gao, Yongxin; Speth, Robert C; Jiang, Nan; Mao, Yingying; Sumners, Colin; Li, Hongwei

    2013-01-01

    Viral vectors have been utilized extensively to introduce genetic material into the central nervous system. In order to investigate gene functions in cardiovascular control regions of rat brain, we applied WPRE (woodchuck hepatitis virus post-transcriptional regulatory element) enhanced-adenoviral (Ad) and adeno-assoicated virus (AAV) type 2 vectors to mediate neuronal gene delivery to the paraventricular nucleus of the hypothalamus, the nucleus tractus solitarius and the rostral ventrolateral medulla, three important cardiovascular control regions known to express renin-angiotensin system (RAS) genes. Ad or AAV2 harboring an enhanced green fluorescent protein (EGFP) reporter gene or the angiotensin type 2 receptor gene were microinjected into these brain regions in adult rats. Our results demonstrated that both AAV2 and Ad vectors elicited long-term neuronal transduction in these regions. Interestingly, we found that the WPRE caused expression of GFP driven by the synapsin1 promoter in pure glial cultures or co-cultures of neurons and glia derived from rat hypothalamus and brainstem. However, in rat paraventricular nucleus WPRE did not cause expression of GFP in glia. This demonstrates the potential use of these vectors in studies of physiological functions of certain genes in the cardiovascular control regions of the brain. PMID:23569423

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

    PubMed Central

    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

    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

  17. Novel approach for operation analysis of vector controlled adjustable speed synchronous machine drives

    Microsoft Academic Search

    G. Zeng; Tung-Hai Chin; M. Nakano

    2000-01-01

    Novel approach for operation analysis of synchronous machine has been described. To draw the vector diagram under adjustable speed operation, the concept of normalized voltage was introduced. It is to divide the voltage value by angular frequency of the machine, and the vector diagram will keep its size unchanged for the whole speed range. Also, reactance drop locus and its

  18. Habitat Hydrology and Geomorphology Control the Distribution of Malaria Vector Larvae in Rural Africa

    PubMed Central

    Hardy, Andrew J.; Gamarra, Javier G. P.; Cross, Dónall E.; Macklin, Mark G.; Smith, Mark W.; Kihonda, Japhet; Killeen, Gerry F.; Ling’ala, George N.; Thomas, Chris J.

    2013-01-01

    Background Larval source management is a promising component of integrated malaria control and elimination. This requires development of a framework to target productive locations through process-based understanding of habitat hydrology and geomorphology. Methods We conducted the first catchment scale study of fine resolution spatial and temporal variation in Anopheles habitat and productivity in relation to rainfall, hydrology and geomorphology for a high malaria transmission area of Tanzania. Results Monthly aggregates of rainfall, river stage and water table were not significantly related to the abundance of vector larvae. However, these metrics showed strong explanatory power to predict mosquito larval abundances after stratification by water body type, with a clear seasonal trend for each, defined on the basis of its geomorphological setting and origin. Conclusion Hydrological and geomorphological processes governing the availability and productivity of Anopheles breeding habitat need to be understood at the local scale for which larval source management is implemented in order to effectively target larval source interventions. Mapping and monitoring these processes is a well-established practice providing a tractable way forward for developing important malaria management tools. PMID:24312606

  19. Application of eco-friendly tools and eco-bio-social strategies to control dengue vectors in urban and peri-urban settings in Thailand

    PubMed Central

    Kittayapong, Pattamaporn; Thongyuan, Suporn; Olanratmanee, Phanthip; Aumchareoun, Worawit; Koyadun, Surachart; Kittayapong, Rungrith; Butraporn, Piyarat

    2012-01-01

    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. PMID:23318236

  20. Kynurenine pathway inhibition reduces central nervous system inflammation in a model of human African trypanosomiasis

    PubMed Central

    Rodgers, Jean; Stone, Trevor W.; Barrett, Michael P.; Bradley, Barbara

    2009-01-01

    Human African trypanosomiasis, or sleeping sickness, is caused by the protozoan parasites Trypanosoma brucei rhodesiense or Trypanosoma brucei gambiense, and is a major cause of systemic and neurological disability throughout sub-Saharan Africa. Following early-stage disease, the trypanosomes cross the blood–brain barrier to invade the central nervous system leading to the encephalitic, or late stage, infection. Treatment of human African trypanosomiasis currently relies on a limited number of highly toxic drugs, but untreated, is invariably fatal. Melarsoprol, a trivalent arsenical, is the only drug that can be used to cure both forms of the infection once the central nervous system has become involved, but unfortunately, this drug induces an extremely severe post-treatment reactive encephalopathy (PTRE) in up to 10% of treated patients, half of whom die from this complication. Since it is unlikely that any new and less toxic drug will be developed for treatment of human African trypanosomiasis in the near future, increasing attention is now being focussed on the potential use of existing compounds, either alone or in combination chemotherapy, for improved efficacy and safety. The kynurenine pathway is the major pathway in the metabolism of tryptophan. A number of the catabolites produced along this pathway show neurotoxic or neuroprotective activities, and their role in the generation of central nervous system inflammation is well documented. In the current study, Ro-61-8048, a high affinity kynurenine-3-monooxygenase inhibitor, was used to determine the effect of manipulating the kynurenine pathway in a highly reproducible mouse model of human African trypanosomiasis. It was found that Ro-61-8048 treatment had no significant effect (P?=?0.4445) on the severity of the neuroinflammatory pathology in mice during the early central nervous system stage of the disease when only a low level of inflammation was present. However, a significant (P?=?0.0284) reduction in the severity of the neuroinflammatory response was detected when the inhibitor was administered in animals exhibiting the more severe, late central nervous system stage, of the infection. In vitro assays showed that Ro-61-8048 had no direct effect on trypanosome proliferation suggesting that the anti-inflammatory action is due to a direct effect of the inhibitor on the host cells and not a secondary response to parasite destruction. These findings demonstrate that kynurenine pathway catabolites are involved in the generation of the more severe inflammatory reaction associated with the late central nervous system stages of the disease and suggest that Ro-61-8048 or a similar drug may prove to be beneficial in preventing or ameliorating the PTRE when administered as an adjunct to conventional trypanocidal chemotherapy. PMID:19339256

  1. Malaria Vector Species

    NSDL National Science Digital Library

    0000-00-00

    A sub-page of the extremely informative VectorBase. This is a worldwide listing of malaria vectors divided into 12 geographic regions following the 1957 classic The Epidemiology and Control of Malaria by MacDonald.

  2. Lethal and pre-lethal effects of a fungal biopesticide contribute to substantial and rapid control of malaria vectors.

    PubMed

    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

    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. PMID:21897846

  3. Hydrologic modeling to screen potential environmental management methods for malaria vector control in Niger

    E-print Network

    Gianotti, Rebecca Louise

    This paper describes the first use of Hydrology-Entomology and Malaria Transmission Simulator (HYDREMATS), a physically based distributed hydrology model, to investigate environmental management methods for malaria vector ...

  4. Computational Study of Fluidic Thrust Vectoring using Separation Control in a Nozzle

    NASA Technical Reports Server (NTRS)

    Deere, Karen; Berrier, Bobby L.; Flamm, Jeffrey D.; Johnson, Stuart K.

    2003-01-01

    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 design and analyze over 60 configurations. Nozzle design variables included cavity convergence angle, cavity length, fluidic injection angle, upstream minimum height, aft deck angle, and aft deck shape. All simulations were computed with a static freestream Mach number of 0.05. a nozzle pressure ratio of 3.858, and a fluidic injection flow rate equal to 6 percent of the primary flow rate. Results indicate that the recessed cavity enhances the throat shifting method of fluidic thrust vectoring and allows for greater thrust-vector angles without compromising thrust efficiency.

  5. Unexpected Failures to Control Chagas Disease Vectors With Pyrethroid Spraying in Northern Argentina

    PubMed Central

    Gurevitz, J. M.; Gaspe, M. S.; Enríquez, G. F.; Vassena, C. V.; Alvarado-Otegui, J. A.; Provecho, Y. M.; Mougabure Cueto, G. A; Picollo, M. I.; Kitron, U.; Gürtler, R. E.

    2013-01-01

    Effectiveness of the elimination efforts against Triatoma infestans (Klug) in South America through residual application of pyrethroid insecticides has been highly variable in the Gran Chaco region. We investigated apparent vector control failures after a standard community-wide spraying with deltamethrin SC in a rural area of northeastern Argentina encompassing 353 houses. Insecticide spraying reduced house infestation less than expected: from 49.5% at baseline to 12.3 and 6.7% at 4 and 8 mo postspraying, respectively. Persistent infestations were detected in 28.4% of houses, and numerous colonies with late-stage bugs were recorded after the interventions. Laboratory bioassays showed reduced susceptibility to pyrethroids in the local bug populations. Eleven of 14 bug populations showed reduced mortality in diagnostic dose assays (range, 35 ± 5% to 97 ± 8%) whereas the remainder had 100% mortality. A fully enclosed residual bug population in a large chicken coop survived four pyrethroid sprays, including two double-dose applications, and was finally suppressed with malathion. The estimated resistance ratio of this bug population was 7.17 (range, 4.47–11.50). Our field data combined with laboratory bioassays and a residual foci experiment demonstrate that the initial failure to suppress T. infestans was mainly because of the unexpected occurrence of reduced susceptibility to deltamethrin in an area last treated with pyrethroid insecticides 12 yr earlier. Our results underline the need for close monitoring of the impact of insecticide spraying to provide early warning of possible problems due to enhanced resistance or tolerance and determine appropriate responses. PMID:23270166

  6. Sleep-wake transition in narcolepsy and healthy controls using a support vector machine.

    PubMed

    Jensen, Julie B; Sorensen, Helge B D; Kempfner, Jacob; Sørensen, Gertrud L; Knudsen, Stine; Jennum, Poul

    2014-10-01

    Narcolepsy is characterized by abnormal sleep-wake regulation, causing sleep episodes during the day and nocturnal sleep disruptions. The transitions between sleep and wakefulness can be identified by manual scorings of a polysomnographic recording. The aim of this study was to develop an automatic classifier capable of separating sleep epochs from epochs of wakefulness by using EEG measurements from one channel. Features from frequency bands ? (0-4 Hz), ? (4-8 Hz), ? (8-12 Hz), ? (12-16 Hz), 16 to 24 Hz, 24 to 32 Hz, 32 to 40 Hz, and 40 to 48 Hz were extracted from data by use of a wavelet packet transformation and were given as input to a support vector machine classifier. The classification algorithm was assessed by hold-out validation and 10-fold cross-validation. The data used to validate the classifier were derived from polysomnographic recordings of 47 narcoleptic patients (33 with cataplexy and 14 without cataplexy) and 15 healthy controls. Compared with manual scorings, an accuracy of 90% was achieved in the hold-out validation, and the area under the receiver operating characteristic curve was 95%. Sensitivity and specificity were 90% and 88%, respectively. The 10-fold cross-validation procedure yielded an accuracy of 88%, an area under the receiver operating characteristic curve of 92%, a sensitivity of 87%, and a specificity of 87%. Narcolepsy with cataplexy patients experienced significantly more sleep-wake transitions during night than did narcolepsy without cataplexy patients (P = 0.0199) and healthy subjects (P = 0.0265). In addition, the sleep-wake transitions were elevated in hypocretin-deficient patients. It is concluded that the classifier shows high validity for identifying the sleep-wake transition. Narcolepsy with cataplexy patients have more sleep-wake transitions during night, suggesting instability in the sleep-wake regulatory system. PMID:25271675

  7. Parasite Prolyl Oligopeptidases and the Challenge of Designing Chemotherapeuticals for Chagas Disease, Leishmaniasis and African Trypanosomiasis

    PubMed Central

    Bastos, I.M.D; Motta, F.N; Grellier, P; Santana, J.M

    2013-01-01

    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. PMID:23514419

  8. Specific Cell Targeting Therapy Bypasses Drug Resistance Mechanisms in African Trypanosomiasis.

    PubMed

    Unciti-Broceta, Juan D; Arias, José L; Maceira, José; Soriano, Miguel; Ortiz-González, Matilde; Hernández-Quero, José; Muñóz-Torres, Manuel; de Koning, Harry P; Magez, Stefan; Garcia-Salcedo, José A

    2015-06-01

    African trypanosomiasis is a deadly neglected disease caused by the extracellular parasite Trypanosoma brucei. Current therapies are characterized by high drug toxicity and increasing drug resistance mainly associated with loss-of-function mutations in the transporters involved in drug import. The introduction of new antiparasitic drugs into therapeutic use is a slow and expensive process. In contrast, specific targeting of existing drugs could represent a more rapid and cost-effective approach for neglected disease treatment, impacting through reduced systemic toxicity and circumventing resistance acquired through impaired compound uptake. We have generated nanoparticles of chitosan loaded with the trypanocidal drug pentamidine and coated by a single domain nanobody that specifically targets the surface of African trypanosomes. Once loaded into this nanocarrier, pentamidine enters trypanosomes through endocytosis instead of via classical cell surface transporters. The curative dose of pentamidine-loaded nanobody-chitosan nanoparticles was 100-fold lower than pentamidine alone in a murine model of acute African trypanosomiasis. Crucially, this new formulation displayed undiminished in vitro and in vivo activity against a trypanosome cell line resistant to pentamidine as a result of mutations in the surface transporter aquaglyceroporin 2. We conclude that this new drug delivery system increases drug efficacy and has the ability to overcome resistance to some anti-protozoal drugs. PMID:26110623

  9. Specific Cell Targeting Therapy Bypasses Drug Resistance Mechanisms in African Trypanosomiasis

    PubMed Central

    Unciti-Broceta, Juan D.; Arias, José L.; Maceira, José; Soriano, Miguel; Ortiz-González, Matilde; Hernández-Quero, José; Muñóz-Torres, Manuel; de Koning, Harry P.; Magez, Stefan; Garcia-Salcedo, José A.

    2015-01-01

    African trypanosomiasis is a deadly neglected disease caused by the extracellular parasite Trypanosoma brucei. Current therapies are characterized by high drug toxicity and increasing drug resistance mainly associated with loss-of-function mutations in the transporters involved in drug import. The introduction of new antiparasitic drugs into therapeutic use is a slow and expensive process. In contrast, specific targeting of existing drugs could represent a more rapid and cost-effective approach for neglected disease treatment, impacting through reduced systemic toxicity and circumventing resistance acquired through impaired compound uptake. We have generated nanoparticles of chitosan loaded with the trypanocidal drug pentamidine and coated by a single domain nanobody that specifically targets the surface of African trypanosomes. Once loaded into this nanocarrier, pentamidine enters trypanosomes through endocytosis instead of via classical cell surface transporters. The curative dose of pentamidine-loaded nanobody-chitosan nanoparticles was 100-fold lower than pentamidine alone in a murine model of acute African trypanosomiasis. Crucially, this new formulation displayed undiminished in vitro and in vivo activity against a trypanosome cell line resistant to pentamidine as a result of mutations in the surface transporter aquaglyceroporin 2. We conclude that this new drug delivery system increases drug efficacy and has the ability to overcome resistance to some anti-protozoal drugs. PMID:26110623

  10. A sensorless stator flux oriented vector controlled induction motor drive with neuro-fuzzy based performance enhancement

    Microsoft Academic Search

    Bimal K. Bose; Nitin R. Patel

    1997-01-01

    A high-performance stator flux oriented speed sensorless direct vector-controlled induction motor drive is described in the paper. The drive can start from stand-still, operate at any speed in all the quadrants including the field-weakening region, and then stop at zero speed. The drive incorporated the following novel features: (1) software-programmable cascaded low-pass filter units permit machine terminal voltage integration to

  11. Power-quality improvements in vector-controlled induction motor drive employing pulse multiplication in AC-DC converters

    Microsoft Academic Search

    Bhim Singh; G. Bhuvaneswari; Vipin Garg

    2006-01-01

    This paper deals with the pulse doubling in a 12-pulse ac-dc converter for improving power quality in vector-controlled induction motor drives (VCIMDs). The design of proposed magnetics shows the flexibility in varying the voltage ratio of the autotransformer for making it suitable for retrofit applications, where presently a six-pulse diode bridge rectifier is being used. The proposed ac-dc converter is

  12. Development and Assessment of Plant-Based Synthetic Odor Baits for Surveillance and Control of Malaria Vectors

    PubMed Central

    Nyasembe, Vincent O.; Tchouassi, David P.; Kirwa, Hillary K.; Foster, Woodbridge A.; Teal, Peter E. A.; Borgemeister, Christian; Torto, Baldwyn

    2014-01-01

    Background Recent malaria vector control measures have considerably reduced indoor biting mosquito populations. However, reducing the outdoor biting populations remains a challenge because of the unavailability of appropriate lures to achieve this. This study sought to test the efficacy of plant-based synthetic odor baits in trapping outdoor populations of malaria vectors. Methodology and Principal Finding Three plant-based lures ((E)-linalool oxide [LO], (E)-linalool oxide and (E)-?-ocimene [LO + OC], and a six-component blend comprising (E)-linalool oxide, (E)-?-ocimene, hexanal, ?-pinene, limonene, and (E)-?-farnesene [Blend C]), were tested alongside an animal/human-based synthetic lure (comprising heptanal, octanal, nonanal, and decanal [Blend F]) and worn socks in a malaria endemic zone in the western part of Kenya. Mosquito Magnet-X (MM-X) and lightless Centre for Disease Control (CDC) light traps were used. Odor-baited traps were compared with traps baited with either solvent alone or solvent + carbon dioxide (controls) for 18 days in a series of randomized incomplete-block designs of days × sites × treatments. The interactive effect of plant and animal/human odor was also tested by combining LO with either Blend F or worn socks. Our results show that irrespective of trap type, traps baited with synthetic plant odors compared favorably to the same traps baited with synthetic animal odors and worn socks in trapping malaria vectors, relative to the controls. Combining LO and worn socks enhanced trap captures of Anopheles species while LO + Blend F recorded reduced trap capture. Carbon dioxide enhanced total trap capture of both plant- and animal/human-derived odors. However, significantly higher proportions of male and engorged female Anopheles gambiae s.l. were caught when the odor treatments did not include carbon dioxide. Conclusion and Significance The results highlight the potential of plant-based odors and specifically linalool oxide, with or without carbon dioxide, for surveillance and mass trapping of malaria vectors. PMID:24587059

  13. Intensified Surveillance and Insecticide-based Control of the Chagas Disease Vector Triatoma infestans in the Argentinean Chaco

    PubMed Central

    Gurevitz, Juan M.; Gaspe, María Sol; Enriquez, Gustavo F.; Provecho, Yael M.; Kitron, Uriel; Gürtler, Ricardo E.

    2013-01-01

    Background The elimination of Triatoma infestans, the main Chagas disease vector in the Gran Chaco region, remains elusive. We implemented an intensified control strategy based on full-coverage pyrethroid spraying, followed by frequent vector surveillance and immediate selective insecticide treatment of detected foci in a well-defined rural area in northeastern Argentina with moderate pyrethroid resistance. We assessed long-term impacts, and identified factors and procedures affecting spray effectiveness. Methods and Findings After initial control interventions, timed-manual searches were performed by skilled personnel in 4,053 sites of 353–411 houses inspected every 4–7 months over a 35-month period. Residual insecticide spraying was less effective than expected throughout the three-year period, mainly because of the occurrence of moderate pyrethroid resistance and the limited effectiveness of selective treatment of infested sites only. After initial interventions, peridomestic infestation prevalence always exceeded domestic infestation, and timed-manual searches consistently outperformed householders' bug detection, except in domiciles. Most of the infestations occurred in houses infested at baseline, and were restricted to four main ecotopes. Houses with an early persistent infestation were spatially aggregated up to a distance of 2.5 km. An Akaike-based multi-model inference approach showed that new site-level infestations increased substantially with the local availability of appropriate refugia for triatomine bugs, and with proximity to the nearest site found infested at one or two preceding surveys. Conclusions and Significance Current vector control procedures have limited effectiveness in the Gran Chaco. Selective insecticide sprays must include all sites within the infested house compound. The suppression of T. infestans in rural areas with moderate pyrethroid resistance requires increased efforts and appropriate management actions. In addition to careful, systematic insecticide applications, housing improvement and development policies that improve material conditions of rural villagers and reduce habitat suitability for bugs will contribute substantially to sustainable vector and disease control in the Gran Chaco. PMID:23593525

  14. Reduced-order extended luenberger observer based sensorless vector control driven by matrix converter with nonlinearity compensation

    Microsoft Academic Search

    Kyo-Beum Lee; Frede Blaabjerg

    2006-01-01

    This paper presents a new sensorless vector control system for high-performance induction motor drives fed by a matrix converter with nonlinearity compensation. The nonlinear voltage distortion that is caused by commutation delay and ON-state voltage drop in the switching devices is corrected by a new matrix converter model. A reduced-order extended Luenberger observer is employed to bring better response in

  15. Preliminary Investigation on Battery Sizing Investigation for Thrust Vector Control on Ares I and Ares V Launch Vehicles

    NASA Technical Reports Server (NTRS)

    Miller, Thomas B.

    2011-01-01

    An investigation into the merits of battery powered Electro Hydrostatic Actuation (EHA) for Thrust Vector Control (TVC) of the Ares I and Ares V launch vehicles is described. A top level trade study was conducted to ascertain the technical merits of lithium-ion (Li-ion) and thermal battery performance to determine the preferred choice of an energy storage system chemistry that provides high power discharge capability for a relatively short duration.

  16. Molecular epidemiology of American trypanosomiasis in Brazil based on dimorphisms of rRNA and mini-exon gene sequences

    Microsoft Academic Search

    B. Zingales; R. P. Souto; R. H. Mangia; C. V. Lisboa; D. A. Campbell; J. R. Coura; A. Jansen; O. Fernandes

    1998-01-01

    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

  17. Value of the indirect fluorescent antibody test as a serological aid to diagnosis of glossina -transmitted bovine trypanosomiasis

    Microsoft Academic Search

    A. J. Wilson

    1969-01-01

    Four hundred and sixty seven cattle were sampled for the presence of trypanosomiasis in two distinct areas of Eastern Uganda. Using sera collected, the agglutination test and two types of indirect fluorescent antibody test were used to examine their value as serological aids to diagnosis. The agglutination test was considered to be of limited use. The indirect fluorescent antibody tests

  18. Multiaxis control power from thrust vectoring for a supersonic fighter aircraft model at Mach 0.20 to 2.47

    NASA Technical Reports Server (NTRS)

    Capone, Francis J.; Bare, E. Ann

    1987-01-01

    The aeropropulsive characteristics of an advanced twin-engine fighter aircraft designed for supersonic cruise have been studied in the Langley 16-Foot Tansonic Tunnel and the Lewis 10- by 10-Foot Supersonic Tunnel. The objective was to determine multiaxis control-power characteristics from thrust vectoring. A two-dimensional convergent-divergent nozzle was designed to provide yaw vector angles of 0, -10, and -20 deg combined with geometric pitch vector angles of 0 and 15 deg. Yaw thrust vectoring was provided by yaw flaps located in the nozzle sidewalls. Roll control was obtained from differential pitch vectoring. This investigation was conducted at Mach numbers from 0.20 to 2.47. Angle of attack was varied from 0 to about 19 deg, and nozzle pressure ratio was varied from about 1 (jet off) to 28, depending on Mach number. Increments in force or moment coefficient that result from pitch or yaw thrust vectoring remain essentially constant over the entire angle-of-attack range of all Mach numbers tested. There was no effect of pitch vectoring on the lateral aerodynamic forces and moments and only very small effects of yaw vectoring on the longitudinal aerodynamic forces and moments. This result indicates little cross-coupling of control forces and moments for combined pitch-yaw vectoring.

  19. Using geographic information systems and decision support systems for the prediction, prevention, and control of vector-borne diseases.

    PubMed

    Eisen, Lars; Eisen, Rebecca J

    2011-01-01

    Emerging and resurging vector-borne diseases cause significant morbidity and mortality, especially in the developing world. We focus on how advances in mapping, Geographic Information System, and Decision Support System technologies, and progress in spatial and space-time modeling, can be harnessed to prevent and control these diseases. Major themes, which are addressed using examples from tick-borne Lyme borreliosis; flea-borne plague; and mosquito-borne dengue, malaria, and West Nile virus disease, include (a) selection of spatial and space-time modeling techniques, (b) importance of using high-quality and biologically or epidemiologically relevant data, (c) incorporation of new technologies into operational vector and disease control programs, (d) transfer of map-based information to stakeholders, and (e) adaptation of technology solutions for use in resource-poor environments. We see great potential for the use of new technologies and approaches to more effectively target limited surveillance, prevention, and control resources and to reduce vector-borne and other infectious diseases. PMID:20868280

  20. Cultivation-Independent Methods Reveal Differences among Bacterial Gut Microbiota in Triatomine Vectors of Chagas Disease

    PubMed Central

    da Mota, Fabio Faria; Marinho, Lourena Pinheiro; Moreira, Carlos José de Carvalho; Lima, Marli Maria; Mello, Cícero Brasileiro; Garcia, Eloi Souza; Carels, Nicolas; Azambuja, Patricia

    2012-01-01

    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. PMID:22563511

  1. Mapping the capacities of fixed health facilities to cover people at risk of gambiense human African trypanosomiasis

    PubMed Central

    2014-01-01

    Background The emphasis placed on the activities of mobile teams in the detection of gambiense human African trypanosomiasis (HAT) can at times obscure the major role played by fixed health facilities in HAT control and surveillance. The lack of consistent and detailed data on the coverage of passive case-finding and treatment further constrains our ability to appreciate the full contribution of the health system to the control of HAT. Methods A survey was made of all fixed health facilities that are active in the control and surveillance of gambiense HAT. Information on their diagnostic and treatment capabilities was collected, reviewed and harmonized. Health facilities were geo-referenced. Time-cost distance analysis was conducted to estimate physical accessibility and the potential coverage of the population at-risk of gambiense HAT. Results Information provided by the National Sleeping Sickness Control Programmes revealed the existence of 632 fixed health facilities that are active in the control and surveillance of gambiense HAT in endemic countries having reported cases or having conducted active screening activities during the period 2000-2012. Different types of diagnosis (clinical, serological, parasitological and disease staging) are available from 622 facilities. Treatment with pentamidine for first-stage disease is provided by 495 health facilities, while for second-stage disease various types of treatment are available in 206 health facilities only. Over 80% of the population at-risk for gambiense HAT lives within 5-hour travel of a fixed health facility offering diagnosis and treatment for the disease. Conclusions Fixed health facilities have played a crucial role in the diagnosis, treatment and coverage of at-risk-population for gambiense HAT. As the number of reported cases continues to dwindle, their role will become increasingly important for the prospects of disease elimination. Future updates of the database here presented will regularly provide evidence to inform and monitor a rational deployment of control and surveillance efforts. Support to the development and, if successful, the implementation of new control tools (e.g. new diagnostics and new drugs) is crucial, both for strengthening and expanding the existing network of fixed health facilities by improving access to diagnosis and treatment and for securing a sustainable control and surveillance of gambiense HAT. PMID:24517513

  2. Reducing costs and operational constraints of dengue vector control by targeting productive breeding places: a multi-country non-inferiority cluster randomized trial

    Microsoft Academic Search

    W. Tun-Lin; A. Lenhart; V. S. Nam; E. Rebollar-Tellez; A. C. Morrison; P. Barbazan; M. Cote; J. Midega; F. Sanchez; P. Manrique-Saide; A. Kroeger; M. B. Nathan; F. Meheus; M. Petzold

    2009-01-01

    OBJECTIVES: To test the non-inferiority hypothesis that a vector control approach targeting only the most productive water container types gives the same or greater reduction of the vector population as a non-targeted approach in different ecological settings and to analyse whether the targeted intervention is less costly. METHODS: Cluster randomized trial in eight study sites (Venezuela, Mexico, Peru, Kenya, Thailand,

  3. Review article Trypanosoma cruzi: adaptation to its vectors and its hosts

    E-print Network

    Paris-Sud XI, Université de

    2009) Abstract ­ American trypanosomiasis is a parasitic zoonosis that occurs throughout Latin America knowledge of the different components involved in elaborate system that is American trypanosomiasis (the

  4. Quantifying the mosquito’s sweet tooth: modelling the effectiveness of attractive toxic sugar baits (ATSB) for malaria vector control

    PubMed Central

    2013-01-01

    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. PMID:23968494

  5. Using global information technology to detect, monitor, and control mosquito pest and disease vector populations.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Geographic Information Systems (GIS), image analysis, and remote sensing comprise global information technologies that are used to characterize pest and vector populations of mosquitoes. At this national meeting, scientists from ARS and McNeese State University organized and convened a half-day sym...

  6. Efficacy of extracts of Bacillus thuringiensis israelensis for the control of mosquito vectors.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    More than 1 million human cases of Chikungunya were recently reported in India. Aedes aegypti (the yellow fever mosquito) is an important disease vector in India where it transmits Chikungunya, dengue, and yellow fever viruses to humans. In this study, scientists from Bharathiar University in Coim...

  7. Gene expression in midgut tissues of Diaphorina citri: Application to biology and vector control

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We produced a gene expression dataset from the midgut tissues of the Asian citrus psyllid (AsCP), Diaphorina citri (Hemiptera: Psyllidae). The AsCP is the primary vector associated with the spread of a devastating citrus trees disease, huanglongbing (HLB). The occurrence and spread of the AsCP and H...

  8. Recombinant viral vectored vaccines for the control of avian influenza: a review

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The poultry industry has been at the forefront of developing recombinant viral vectored vaccines in an attempt to improve the immune response to vaccination. With AIV, the hemagglutinin surface glycoprotein is the key antigen for protection against infection. This allows a single gene to be transf...

  9. Efficient generation of double heterologous promoter controlled oncolytic adenovirus vectors by a single homologous recombination step in Escherichia coli

    PubMed Central

    Hoffmann, Dennis; Wildner, Oliver

    2006-01-01

    Background Oncolytic adenoviruses are promising agents for the multimodal treatment of cancer. However, tumor-selectivity is crucial for their applicability in patients. Recent studies by several groups demonstrated that oncolytic adenoviruses with tumor-/tissue-specific expression of the E1 and E4 genes, which are pivotal for adenoviral replication, have a specificity profile that is superior to viruses that solely target the expression of E1 or E4 genes. Presently the E1 and E4 regions are modified in a time consuming sequential fashion. Results Based on the widely used adenoviral cloning system AdEasy we generated a novel transfer vector that allows efficient and rapid generation of conditionally replication-competent adenovirus type 5 based vectors with the viral E1 and E4 genes under the transcriptional control of heterologous promoters. For insertion of the promoters of interest our transfer vector has two unique multiple cloning sites. Additionally, our shuttle plasmid allows encoding of a transgene within the E1A transcription unit. The modifications, including E1 mutations, are introduced into the adenoviral genome by a single homologous recombination step in Escherichia coli. Subsequently infectious viruses are rescued from plasmids. As a proof-of-concept we generated two conditionally replication-competent adenoviruses Ad.Ki•COX and Ad.COX•Ki with the promoters of the Ki-67 protein and the cyclooxygenase-2 (COX-2) driving E1 and E4 and vice versa. Conclusion We demonstrated with our cloning system efficient generation of double heterologous promoter controlled oncolytic adenoviral vectors by a single homologous recombination step in bacteria. The generated viruses showed preferential replication in tumor cells and in a subcutaneous HT-29 colon cancer xenograft model the viruses demonstrated significant oncolytic activity comparable with dl327. PMID:16887042

  10. A Method for Integrating Thrust-Vectoring and Actuated Forebody Strakes with Conventional Aerodynamic Controls on a High-Performance Fighter Airplane

    NASA Technical Reports Server (NTRS)

    Lallman, Frederick J.; Davidson, John B.; Murphy, Patrick C.

    1998-01-01

    A method, called pseudo controls, of integrating several airplane controls to achieve cooperative operation is presented. The method eliminates conflicting control motions, minimizes the number of feedback control gains, and reduces the complication of feedback gain schedules. The method is applied to the lateral/directional controls of a modified high-performance airplane. The airplane has a conventional set of aerodynamic controls, an experimental set of thrust-vectoring controls, and an experimental set of actuated forebody strakes. The experimental controls give the airplane additional control power for enhanced stability and maneuvering capabilities while flying over an expanded envelope, especially at high angles of attack. The flight controls are scheduled to generate independent body-axis control moments. These control moments are coordinated to produce stability-axis angular accelerations. Inertial coupling moments are compensated. Thrust-vectoring controls are engaged according to their effectiveness relative to that of the aerodynamic controls. Vane-relief logic removes steady and slowly varying commands from the thrust-vectoring controls to alleviate heating of the thrust turning devices. The actuated forebody strakes are engaged at high angles of attack. This report presents the forward-loop elements of a flight control system that positions the flight controls according to the desired stability-axis accelerations. This report does not include the generation of the required angular acceleration commands by means of pilot controls or the feedback of sensed airplane motions.

  11. Vector-borne parasitic diseases: new trends in data collection and risk assessment.

    PubMed

    Bergquist, N R

    2001-04-27

    Climates and topography effectively restrict vector-borne infections to certain geographical areas, a clear illustration of how strongly the spatial distributions of these diseases rely on environmental factors. This is hardly a new revelation, but just a few years back, without the support of computer-assisted collection and handling of data, we were far less able to grasp the full picture. Fortunately climate data collection by Remote Sensing (RS) by earth-observing satellites, a technology particularly well suited to pinpointing constraining endemic factors, has not only become affordable but also reached a high degree of sophistication. Meanwhile, geographical information systems (GIS) and global positioning systems (GPS) permit spatial information of great accuracy as well as digitalization of collected data on the spot enabling visualization of the data in relation to physical maps and facilitating comparisons of the results of longitudinal investigations. Adoption of these technologies at the national level promotes intersectoral collaboration and promises improved planning and management in the control of endemic diseases. Applications in areas such as malaria, onchocerciasis, lymphatic filariasis, trypanosomiasis and schistosomiasis are briefly reviewed. Reports in the fields of the former two diseases dominate the literature, while information is lagging with regard to the others. The need for a broadening of the GIS approach is emphasized with the aim of rejuvenating the dynamic aspect of epidemiological studies. PMID:11378138

  12. Seroprevalence of canine leishmaniasis and American trypanosomiasis in dogs from Grenada, West Indies.

    PubMed

    Rosypal, Alexa C; Tripp, Shanesha; Kinlaw, Christopher; Sharma, R N; Stone, D; Dubey, J P

    2010-02-01

    Canine leishmaniasis and American trypanosomiasis (AT) are caused by related hemoflagellated parasites, Leishmania spp. and Trypanosoma cruzi, which share several common host species. Dogs are reservoirs for human infections by both pathogens. We determined the prevalence of antibodies to Leishmania spp. and T. cruzi in dogs from Grenada, West Indies. We examined 70 dog sera using the qualitative immunochromatographic dipstick tests (ICTs) based on recombinant antigens specific for visceral leishmaniasis and AT. Antibodies to visceral Leishmania were not detected in Grenadian dogs by ICT. Using the canine dipsticks for AT, antibodies to T. cruzi were determined in 3 (4.3%) of the 70 dogs. Results from this study indicate that dogs in Grenada are exposed in low levels to T. cruzi , but not to visceral Leishmania spp. at all. PMID:19712013

  13. New Insights in Staging and Chemotherapy of African Trypanosomiasis and Possible Contribution of Medicinal Plants

    PubMed Central

    Seke Etet, Paul F.; Fawzi Mahomoodally, M.

    2012-01-01

    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

  14. Can malaria vector control accelerate the interruption of lymphatic filariasis transmission in Africa; capturing a window of opportunity?

    PubMed Central

    2013-01-01

    Background The Global Programme to Eliminate Lymphatic Filariasis (GPELF) was launched in 2000, and nearly all endemic countries in the Americas, Eastern Mediterranean and Asia-Pacific regions have now initiated the WHO recommended mass drug administration (MDA) campaign to interrupt transmission of the parasite. However, nearly 50% of the LF endemic countries in Africa are yet to implement the GPELF MDA strategy, which does not include vector control. Nevertheless, the recent scale up in insecticide treated /long lasting nets (ITNs/LLINs) and indoor residual spraying (IRS) for malaria control in Africa may significantly impact LF transmission because the parasite is transmitted mainly by Anopheles mosquitoes. This study examined the magnitude, geographical extent and potential impact of vector control in the 17 African countries that are yet to or have only recently started MDA. Methods National data on mosquito bed nets, ITNs/LLINs and IRS were obtained from published literature, national reports, surveys and datasets from public sources such as Demographic Health Surveys, Malaria Indicator Surveys, Multiple Indicator Cluster Surveys, Malaria Report, Roll Back Malaria and President’s Malaria Initiative websites. The type, number and distribution of interventions were summarised and mapped at sub-national level. and compared with known or potential LF distributions, and those which may be co-endemic with Loa loa and MDA is contraindicated. Results Analyses found that vector control activities had increased significantly since 2005, with a three-fold increase in ITN ownership and IRS coverage. However, coverage varied dramatically across the 17 countries; some regions reported >70% ITNs ownership and regular IRS activity, while others had no coverage in remote rural populations where the risk of LF was potentially high and co-endemic with high risk L.loa. Conclusions Despite many African countries being slow to initiate MDA for LF, the continued commitment and global financial support for NTDs, and the concurrent expansion of vector control activities for malaria, is promising. It is not beyond the capacity of GPELF to reach its target of global LF elimination by 2020, but monitoring and evaluating the impact of these activities over the next decade will be critical to its success. PMID:23433078

  15. Domestic pigs as potential reservoirs of human and animal trypanosomiasis in Northern Tanzania

    PubMed Central

    2013-01-01

    Background Pig keeping is becoming increasingly common across sub-Saharan Africa. Domestic pigs from the Arusha region of northern Tanzania were screened for trypanosomes using PCR-based methods to examine the role of pigs as a reservoir of human and animal trypanosomiasis. Methods A total of 168 blood samples were obtained from domestic pigs opportunistically sampled across four districts in Tanzania (Babati, Mbulu, Arumeru and Dodoma) during December 2004. A suite of PCR-based methods was used to identify the species and sub-species of trypanosomes including: Internally Transcribed Sequence to identify multiple species; species specific PCR to identify T. brucei s. l. and T. godfreyi and a multiplex PCR reaction to distinguish T. b. rhodesiense from T. brucei s. l. Results Of the 168 domestic pigs screened for animal and human infective trypanosome DNA, 28 (16.7%) were infected with one or more species of trypanosome; these included: six pigs infected with Trypanosoma vivax (3.6%); three with Trypanosoma simiae (1.8%); two with Trypanosoma congolense (Forest) (1%) and four with Trypanosoma godfreyi (2.4%). Nineteen pigs were infected with Trypanosoma brucei s. l. (10.1%) of which eight were identified as carrying the human infective sub-species Trypanosoma brucei rhodesiense (4.8%). Conclusion These results show that in Tanzania domestic pigs may act as a significant reservoir for animal trypanosomiasis including the cattle pathogens T. vivax and T. congolense, the pig pathogen T. simiae, and provide a significant reservoir for T. b. rhodesiense, the causative agent of acute Rhodesian sleeping sickness. PMID:24499540

  16. Participatory Mapping as a Component of Operational Malaria Vector Control in Tanzania

    Microsoft Academic Search

    Stefan Dongus; Victoria Mwakalinga; Khadija Kannady; Marcel Tanner; Gerry Killeen

    \\u000a Global efforts to tackle malaria have gained unprecedented momentum. However, in order to move towards the ambitious goal\\u000a of eliminating and eventually eradicating malaria, existing tools must be improved and new tools developed. The City of Dar\\u000a es Salaam, Tanzania, is home to the first operational community-based larviciding programme targeting malaria vectors in modern\\u000a Africa. In an attempt to optimize

  17. The potential of ivermectin to control the malaria vector Anopheles farauti

    Microsoft Academic Search

    D. H. Foley; J. H. Bryan; G. W. Lawrence

    2000-01-01

    We investigated mortality in Anopheles farauti mosquitoes, a major coastal malaria vector in the south-west Pacific, fed on a volunteer who had taken a 250 ?g\\/kg dose of ivermectin. High mortality was recorded in mosquitoes feeding during the first week after treatment of the volunteer, for instance 100-80% failed to survive 3 days. A long-term residual effect of ivermectin in

  18. Conundrums of a complex vector for invasive species control: a detailed examination of the horticultural industry

    Microsoft Academic Search

    Jennifer Drew; Neil Anderson; David Andow

    2010-01-01

    Historically the horticultural industry has transformed the US landscape through intentional cultivar introductions and unintentional\\u000a introductions of weeds, insects and plant diseases. While it has been demonstrated that the horticultural industry, in particular\\u000a the ornamental subsector, is an important vector for the introduction and dispersal of invasive species, known invasive plants\\u000a continue to be sold while new cultivars are introduced

  19. Space vector control and current harmonics in quasi-resonant soft-switching PWM conversion

    Microsoft Academic Search

    Luigi Malesani; Paolo Tomasin; Vanni Toigo

    1996-01-01

    The paper presents an analysis of the behavior of the modulation schemes useful for the soft-switched, quasi-resonant VSI power inverter in comparison with standard PWM techniques (sine-triangle and space-vector). Although the presence of a purely capacitive snubber across each power device in such kinds of converters allows true PWM, this is affected by some constraints in the switching sequence depending

  20. Spatial orientation and balance control changes induced by altered gravitoinertial force vectors

    NASA Technical Reports Server (NTRS)

    Kaufman, G. D.; Wood, S. J.; Gianna, C. C.; Black, F. O.; Paloski, W. H.

    2001-01-01

    To better understand the mechanisms of human adaptation to rotating environments, we exposed 19 healthy subjects and 8 vestibular-deficient subjects ("abnormal"; four bilateral and four unilateral lesions) to an interaural centripetal acceleration of 1 g (resultant 45 degrees roll-tilt of 1.4 g) on a 0.8-m-radius centrifuge for periods of 90 min. The subjects sat upright (body z-axis parallel to centrifuge rotation axis) in the dark with head stationary, except during 4 min of every 10 min, when they performed head saccades toward visual targets switched on at 3- to 5-s intervals at random locations (within +/- 30 degrees) in the earth-horizontal plane. Eight of the normal subjects also performed the head saccade protocol in a stationary chair adjusted to a static roll-tilt angle of 45 degrees for 90 min (reproducing the change in orientation but not the magnitude of the gravitoinertial force on the centrifuge). Eye movements, including voluntary saccades directed along perceived earth- and head-referenced planes, were recorded before, during, and immediately after centrifugation. Postural center of pressure (COP) and multisegment body kinematics were also gathered before and within 10 min after centrifugation. Normal subjects overestimated roll-tilt during centrifugation and revealed errors in perception of head-vertical provided by directed saccades. Errors in this perceptual response tended to increase with time and became significant after approximately 30 min. Motion-sickness symptoms caused approximately 25% of normal subjects to limit their head movements during centrifugation and led three normal subjects to stop the test early. Immediately after centrifugation, subjects reported feeling tilted 10 degrees in the opposite direction, which was in agreement with the direction of their earth-referenced directed saccades. Postural COP, segmental body motion amplitude, and hip-sway frequency increased significantly after centrifugation. These postural effects were short-lived, however, with a recovery time of several postural test trials (minutes). There were also asymmetries in the direction of postcentrifugation COP and head tilt which depended on the subject's orientation during the centrifugation adaptation period (left ear or right ear out). The amount of total head movements during centrifugation correlated poorly or inversely with postcentrifugation postural stability, and the most unstable subject made no head movements. There was no decrease in postural stability after static tilt, although these subjects also reported a perceived tilt briefly after return to upright, and they also had COP asymmetries. Abnormal subjects underestimated roll-tilt during centrifugation, and their directed saccades revealed permanent spatial distortions. Bilateral abnormal subjects started out with poor postural control, but showed no postural decrements after centrifugation, while unilateral abnormal subjects had varying degrees of postural decrement, both in their everyday function and as a result of experiencing the centrifugation. In addition, three unilateral, abnormal subjects, who rode twice in opposite orientations, revealed a consistent orthogonal pattern of COP offsets after centrifugation. These results suggest that both orientation and magnitude of the gravitoinertial vector are used by the central nervous system for calibration of multiple orientation systems. A change in the background gravitoinertial force (otolith input) can rapidly initiate postural and perceptual adaptation in several sensorimotor systems, independent of a structured visual surround.

  1. Progress in directed energy control of vectors for microbes and other cells

    NASA Astrophysics Data System (ADS)

    Kiel, Johnathan L.; Parker, Jill E.; Holwitt, Eric A.; Vivekananda, Jeeva; Sloan, Mark A.; Stribling, Lucille J. V.

    2004-07-01

    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.

  2. Novel, Meso-Substituted Cationic Porphyrin Molecule for Photo-Mediated Larval Control of the Dengue Vector Aedes aegypti

    PubMed Central

    Lucantoni, Leonardo; Magaraggia, Michela; Lupidi, Giulio; Ouedraogo, Robert Kossivi; Coppellotti, Olimpia; Esposito, Fulvio; Fabris, Clara; Jori, Giulio; Habluetzel, Annette

    2011-01-01

    Background Control of the mosquito vector population is the most effective strategy currently available for the prevention of dengue fever and the containment of outbreaks. Photo-activated oxidants may represent promising tools for developing effective, safe and ecofriendly novel larvicides. The purpose of this study was to evaluate the potential of the synthetic meso-substituted porphyrin meso-tri(N-methylpyridyl), meso-mono(N-tetradecylpyridyl)porphine (C14) as a photoactivatable larvicide against the dengue vector Aedes (Stegomyia) aegypti. Methodology The photophysical and photochemical properties of the C14 molecule were assessed spectrophotometrically. Photomediated larvicidal efficacy, route of intake and site of action were determined on Ae. aegypti larvae by laboratory bioassays and fluorescence microscopy. Using powdered food pellet for laboratory rodents (a common larval food used in the laboratory) as a carrier for C14, loading-release dynamics, larvicidal efficacy and residual activity of the C14-carrier complex were investigated. Main Findings The C14 molecule was found to exert a potent photosensitizing activity on Ae. aegypti larvae. At irradiation intervals of 12 h and 1 h, at a light intensity of 4.0 mW/cm2, which is 50–100 times lower than that of natural sunlight, LC50 values of 0.1 µM (0.15 mg/l) and 0.5 µM (0.77 mg/l) were obtained, respectively. The molecule was active after ingestion by the larvae and caused irreversible, lethal damage to the midgut and caecal epithelia. The amphiphilic nature of C14 allowed a formulate to be produced that not only was as active against the larvae as C14 in solution, but also possessed a residual activity of at least two weeks, in laboratory conditions. Conclusions The meso-substituted synthetic porphyrin C14, thanks to its photo-sensitizing properties represents an attractive candidate for the development of novel photolarvicides for dengue vector control. PMID:22206031

  3. Vector control improves survival of three species of prairie dogs (Cynomys) in areas considered enzootic for plague.

    PubMed

    Biggins, Dean E; Godbey, Jerry L; Gage, Kenneth L; Carter, Leon G; Montenieri, John A

    2010-01-01

    Plague causes periodic epizootics that decimate populations of prairie dogs (PDs) (Cynomys), but the means by which the causative bacterium (Yersinia pestis) persists between epizootics are poorly understood. Plague epizootics in PDs might arise as the result of introductions of Y. pestis from sources outside PD colonies. However, it remains possible that plague persists in PDs during interepizootic periods and is transmitted at low rates among highly susceptible individuals within and between their colonies. If this is true, application of vector control to reduce flea numbers might reduce mortality among PDs. To test whether vector control enhances PD survival in the absence of obvious plague epizootics, we reduced the numbers of fleas (vectors for Y. pestis) 96-98% (1 month posttreatment) on 15 areas involving three species of PDs (Cynomys leucurus, Cynomys parvidens in Utah, and Cynomys ludovicianus in Montana) during 2000-2004 using deltamethrin dust delivered into burrows as a pulicide. Even during years without epizootic plague, PD survival rates at dusted sites were 31-45% higher for adults and 2-34% higher for juveniles compared to survival rates at nondusted sites. Y. pestis was cultured from 49 of the 851 flea pools tested (6882 total fleas) and antibodies against Y. pestis were identified in serum samples from 40 of 2631 PDs. Although other explanations are possible, including transmission of other potentially fatal pathogens by fleas, ticks, or other ectoparasites, our results suggest that plague might be maintained indefinitely in PD populations in the absence of free epizootics and widespread mortality among these animals. If PDs and their fleas support enzootic cycles of plague transmission, there would be important implications for the conservation of these animals and other species. PMID:20158328

  4. Vector control measures failed to affect genetic structure of Aedes aegypti in a sentinel metropolitan area of Brazil.

    PubMed

    Souza, Kathleen R; Ribeiro, Gilmar; Silva dos Santos, Carlos Gustavo; de Lima, Eliaci Couto; Melo, Paulo R S; Reis, Mitermayer G; Blanton, Ronald E; Silva, Luciano K

    2013-12-01

    In order to evaluate subpopulation differentiation, effective population size (Ne) and evidence for population bottlenecks at various geographic levels, Aedes aegypti larvae were collected longitudinally from 2007 to 2009 from four areas in the city of Salvador, Brazil. The DNA from each larva was isolated and genotyped with five independent microsatellite markers. FST and Jost's D revealed significant population structuring (P<0.05) at the municipal and regional levels, while only RST was able to detect genetic differentiation at the level of strata within these areas. Ne analysis from longitudinal data did not show any evidence of significant change in population structure. The census population measured by the house index, however, showed a significant trend toward decrease in these areas. Active vector control measures did contribute to vector reduction, but this was not enough to decrease A. aegypti population genetic diversity in Salvador. The understanding of A. aegypti population dynamics may be helpful for planning and evaluation of control measures to make them more effective. PMID:24028791

  5. Microbial symbiosis and the control of vector-borne pathogens in tsetse flies, human lice, and triatomine bugs.

    PubMed

    Sassera, Davide; Epis, Sara; Pajoro, Massimo; Bandi, Claudio

    2013-09-01

    Symbiosis is a widespread biological phenomenon, and is particularly common in arthropods. Bloodsucking insects are among the organisms that rely on beneficial bacterial symbionts to complement their unbalanced diet. This review is focused on describing symbiosis, and possible strategies for the symbiont-based control of insects and insect-borne diseases, in three bloodsucking insects of medical importance: the flies of the genus Glossina, the lice of the genus Pediculus, and triatomine bugs of the subfamily Triatominae. Glossina flies are vector of Trypanosoma brucei, the causative agent of sleeping sickness and other pathologies. They are also associated with two distinct bacterial symbionts, the primary symbiont Wigglesworthia spp., and the secondary, culturable symbiont Sodalis glossinidius. The primary symbiont of human lice, Riesia pediculicola, has been shown to be fundamental for the host, due to its capacity to synthesize B-group vitamins. An antisymbiotic approach, with antibiotic treatment targeted on the lice symbionts, could represent an alternative strategy to control these ectoparasites. In the case of triatominae bugs, the genetic modification of their symbiotic Rhodococcus bacteria, for production of anti-Trypanosoma molecules, is an example of paratransgenesis, i.e. the use of symbiotic microorganism engineered in order to reduce the vector competence of the insect host. PMID:24188239

  6. Preliminary Characterization of the Altair Lunar Lander Slosh Dynamics and Some Implications for the Thrust Vector Control Design

    NASA Technical Reports Server (NTRS)

    Lee, Allan Y.; Strahan, Alan; Tanimoto, Rebekah; Casillas, Arturo

    2010-01-01

    This paper describes a conceptual design of the Thrust Vector Control (TVC) system and preliminary modeling of propellant slosh, for the Altair Lunar Lander. Altair is a vehicle element of the NASA Constellation Program aimed at returning humans to the moon. Guidance, Navigation, and Control (GN&C) is the measurement and control of spacecraft position, velocity, and attitude in support of mission objectives. One key GN&C function is the commanding of effectors that control attitude and impart delta V on the vehicle, utilizing both reaction control system (RCS) thrusters and throttling and TVC gimbaling of the vehicle main engine. Both the Altair descent and ascent modules carry fuel tanks. During thrusting maneuvers, the sloshing of liquid fuels in partially filled tanks can interact with the controlled system in such a way as to cause the overall system to be unstable. These fuel tanks must be properly placed, relative to the spacecraft's c.m., to avoid any unstable interactions. Following this will be a discussion of propellant slosh modeling work performed for the present vehicle configuration, including slosh frequency and participatory fluid mass predictions. Knowing the range of slosh mode frequencies over mission phases, the TVC bandwidth must be carefully selected so as not to excite the slosh modes at those frequencies. The likely need to increase the damping factor of slosh modes via baffles will also be discussed. To conclude, a discussion of operations procedures aimed at minimizing TVC-slosh interactions will be given.

  7. Modified vector control algorithm for increasing partial-load efficiency of fractional-slot concentrated-winding surface PM machines

    SciTech Connect

    El-Refaie, Ayman M [ORNL; Jahns, Thomas M [ORNL; Reddy, Patel [University of Wisconsin; McKeever, John W [ORNL

    2008-01-01

    This paper presents a modified vector control algorithm for a fractional-slot concentrated-winding surface permanent magnet (SPM) 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 for a 55-kW (peak) SPM 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 r/min compared to the maximum torque/ampere algorithm, making the machine much more attractive for its intended application.

  8. Modified vector control algorithm for increasing partial-load efficiency of fractional-slot concentrated-winding surface PM machines

    SciTech Connect

    El-Refaie, Ayman M [ORNL; Jahns, Thomas M [ORNL; Reddy, Patel [University of Wisconsin; McKeever, John W [ORNL

    2006-01-01

    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

  9. The Importance of Veterinary Policy in Preventing the Emergence and Re-Emergence of Zoonotic Disease: Examining the Case of Human African Trypanosomiasis in Uganda

    PubMed Central

    Okello, Anna L.; Welburn, Susan C.

    2014-01-01

    Rapid changes in human behavior, resource utilization, and other extrinsic environmental factors continue to threaten the current distribution of several endemic and historically neglected zoonoses in many developing regions worldwide. There are numerous examples of zoonotic diseases which have circulated within relatively localized geographical areas for some time, before emerging into new regions as a result of changing human, environmental, or behavioral dynamics. While the world’s focus is currently on the Ebola virus gaining momentum in western Africa, another pertinent example of this phenomenon is zoonotic human African trypanosomiasis (HAT), endemic to south and eastern Africa, and spread via infected cattle. In recent years, the ongoing northwards spread of this disease in the country has posed a serious public health threat to the human population of Uganda, increasing the pressure on both individual families and government services to control the disease. Moreover, the emergence of HAT into new areas of Uganda in recent years exemplifies the important role of veterinary policy in mitigating the severe human health and economic impacts of zoonotic disease. The systemic challenges surrounding the development and enforcement of veterinary policy described here are similar across sub-Saharan Africa, highlighting the necessity to consider and support zoonotic disease control in broader human and animal health systems strengthening and associated development programs on the continent. PMID:25405148

  10. wFlu: Characterization and Evaluation of a Native Wolbachia from the Mosquito Aedes fluviatilis as a Potential Vector Control Agent

    PubMed Central

    Gonçalves, Daniela da Silva; Moreira, Luciano Andrade

    2013-01-01

    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. PMID:23555728

  11. Performance Improvement of the IPMSM Position Sensor-less Vector Control System by the On-line Motor Parameter Error Compensation and the Practical Dead-time Compensation

    Microsoft Academic Search

    Tetsuya Fukumoto; Hiroto Hamane; Y. Hayashi

    2007-01-01

    This paper proposes the performance improvement methods for the IPMSM position sensor-less vector control system. The stability of the position sensor-less control is influenced by the motor parameter error and dead time compensation error. Especially, it becomes problem in case of the extreme temperature variation and at low speed. The influence on the position estimation is analyzed for the proposed

  12. Stator-flux-based vector control of induction machines in magnetic saturation

    SciTech Connect

    Hofmann, H.; Sanders, S.R.; Sullivan, C. [Univ. of California, Berkeley, CA (United States). Dept. of Electrical Engineering and Computer Sciences

    1995-12-31

    In many variable-torque applications of induction machines it is desirable to operate the machine in magnetic saturation, thus allowing the machine to produce higher torques. Stator-flux-based control schemes have been developed as a possible alternative method of control of induction machines. Stator-flux-based control schemes need not depend on the magnetic characteristics of the machine, and hence are potentially more robust and easier to implement in magnetic saturation than rotor-flux-based control. The authors analyze the induction machine in saturation using a nonlinear {pi}-model of the machine`s magnetics, and develop a control scheme in the stator flux reference frame that is independent of magnetics. Experiments carried out on a 3 hp, 1,800 rpm wound rotor induction machine show smooth operation of the control scheme at torque levels up to at least 4 times rated torque.

  13. 7/9/10 2:34 PMWHO | Human African trypanosomiasis: number of new cases drops to historically low level in 50 years Page 1 of 2http://www.who.int/neglected_diseases/integrated_media/integrated_media_hat_june_2010/en/index.html

    E-print Network

    Cross, George

    7/9/10 2:34 PMWHO | Human African trypanosomiasis: number of new cases drops to historically low tropical diseases > Integrated media related to NTD printable version Human African trypanosomiasis: number of human African trypanosomiasis (also known as sleeping sickness) reported to WHO has dropped below 10 000

  14. Population size and migration of Anopheles gambiae in the Bancoumana Region of Mali and their significance for efficient vector control.

    PubMed

    Baber, Ibrahima; Keita, Moussa; Sogoba, Nafomon; Konate, Mamadou; Diallo, M'Bouye; Doumbia, Seydou; Traoré, Sékou F; Ribeiro, José M C; Manoukis, Nicholas C

    2010-01-01

    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

  15. An Improved Sliding Mode Observer for Speed Sensorless Vector Control Drive of PMSM

    Microsoft Academic Search

    K. Paponpen; M. Konghirun

    2006-01-01

    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

  16. On-line parameter identification for vector controlled PMSM drives using adaptive algorithm

    Microsoft Academic Search

    Quntao An; Li Sun

    2008-01-01

    In advanced PI type and sensorless control systems of motors, the precise determination of permanent magnet synchronous motor (PMSM) parameters is of great significance. By means of the field orientation control principle of PMSM and Popov super stability theory, a novel adaptive online identification method of motor parameters is proposed in this paper. Resistance, inductance and PM flux of PMSM

  17. Study on an Application of Induction Motor Speed Sensorless Vector Control to Railway Vehicle Traction

    NASA Astrophysics Data System (ADS)

    Kondo, Keiichiro; Yuki, Kazuaki

    The Pulse Generators or PGs are equipped to detect the rotor frequency of induction traction motors for the torque control in railway vehicle traction field. Eliminating PGs are preferable from the view points of increasing the reliability of the traction system, reduction of the both initial and maintenance cost and down-sizing induction traction motors. Expecting those merits, we have been studying to apply a sensor less control method to induction traction motor control. Prior to some reports of studies and tests to apply speed sensor-less strategy to railway vehicle traction, we lunched the ideas to apply the speed sensor-less control strategy and results of the studies and the tests. In this paper, we present the novel control method for railway vehicle traction and some results of theoretical study and tests.

  18. A Randomized Longitudinal Factorial Design to Assess Malaria Vector Control and Disease Management Interventions in Rural Tanzania

    PubMed Central

    Kramer, Randall A.; Mboera, Leonard E. G.; Senkoro, Kesheni; Lesser, Adriane; Shayo, Elizabeth H.; Paul, Christopher J.; Miranda, Marie Lynn

    2014-01-01

    The optimization of malaria control strategies is complicated by constraints posed by local health systems, infrastructure, limited resources, and the complex interactions between infection, disease, and treatment. The purpose of this paper is to describe the protocol of a randomized factorial study designed to address this research gap. This project will evaluate two malaria control interventions in Mvomero District, Tanzania: (1) a disease management strategy involving early detection and treatment by community health workers using rapid diagnostic technology; and (2) vector control through community-supported larviciding. Six study villages were assigned to each of four groups (control, early detection and treatment, larviciding, and early detection and treatment plus larviciding). The primary endpoint of interest was change in malaria infection prevalence across the intervention groups measured during annual longitudinal cross-sectional surveys. Recurring entomological surveying, household surveying, and focus group discussions will provide additional valuable insights. At baseline, 962 households across all 24 villages participated in a household survey; 2,884 members from 720 of these households participated in subsequent malariometric surveying. The study design will allow us to estimate the effect sizes of different intervention mixtures. Careful documentation of our study protocol may also serve other researchers designing field-based intervention trials. PMID:24840349

  19. Vector Introduction Vector components and example machines

    E-print Network

    California at Berkeley, University of

    vector 1 Vector Introduction Lecture 10 2/21/96 vector 2 Outline Motivation Vector components and example machines Vector instructions & vector program Vector Execution Vector Load/Store Units Vector Length, Stride, Strip Mining Vector Optimizations: Chaining, Gather/Scatter, Conditional Vector Metrics

  20. Configuration management and automatic control of an augmentor wing aircraft with vectored thrust

    NASA Technical Reports Server (NTRS)

    Cicolani, L. S.; Sridhar, B.; Meyer, G.

    1979-01-01

    An advanced structure for automatic flight control logic for powered-lift aircraft operating in terminal areas is under investigation at Ames Research Center. This structure is based on acceleration control; acceleration commands are constructed as the sum of acceleration on the reference trajectory and a corrective feedback acceleration to regulate path tracking errors. The central element of the structure, termed a Trimmap, uses a model of the aircraft aerodynamic and engine forces to calculate the control settings required to generate the acceleration commands. This report describes the design criteria for the Trimmap and derives a Trimmap for Ames experimental augmentor wing jet STOL research aircraft.

  1. Monitoring of larval habitats and mosquito densities in the Sudan savanna of Mali: implications for malaria vector control.

    PubMed

    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

    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

  2. Turning cigarette butt waste into an alternative control tool against an insecticide-resistant mosquito vector.

    PubMed

    Dieng, Hamady; Rajasaygar, Sudha; Ahmad, Abu Hassan; Ahmad, Hamdan; Rawi, Che Salmah Md; Zuharah, Wan Fatma; Satho, Tomomitsu; Miake, Fumio; Fukumitsu, Yuki; Saad, Ahmad Ramli; Ghani, Idris Abd; Vargas, Ronald Enrique Morales; Majid, Abdul Hafiz Ab; Abubakar, Sazaly

    2013-12-01

    Annually, 4.5 trillion cigarette butts (CBs) are flicked into our environment. Evidence exists that CB waste is deadly to aquatic life, but their lethality to the aquatic life of the main dengue vector is unknown. CBs are full of toxicants that occur naturally, during planting and manufacturing, which may act as larvicidal agents. We assessed Aedes aegypti vulnerability to Marlboro butts during its development. Overall, CBs showed insecticidal activities against larvae. At early phases of development, mortality rates were much higher in two CBs solution (2CBSol) and 3CBSol microcosms (MICRs). Larval survival gradually decreased with development in 1CBSol-MICRs. However, in great presence of CBs, mortality was high even for the late developmental stages. These results suggest that A. aegypti larvae are vulnerable to CB presence in their habitats, but this effect was seen most during the early developmental phases and in the presence of increased amounts of cigarette remnants. CB filters are being used as raw material in many sectors, i.e., brick, art, fashion, plastic industries, as a practical solution to the pollution problem, the observed butt waste toxicity to mosquito larvae open new avenues for the identification of novel insecticide products. PMID:23999373

  3. Dynamics of the “Popcorn” Wolbachia Infection in Outbred Aedes aegypti Informs Prospects for Mosquito Vector Control

    PubMed Central

    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.

    2011-01-01

    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

  4. Design Specification for a Thrust-Vectoring, Actuated-Nose-Strake Flight Control Law for the High-Alpha Research Vehicle

    NASA Technical Reports Server (NTRS)

    Bacon, Barton J.; Carzoo, Susan W.; Davidson, John B.; Hoffler, Keith D.; Lallman, Frederick J.; Messina, Michael D.; Murphy, Patrick C.; Ostroff, Aaron J.; Proffitt, Melissa S.; Yeager, Jessie C.; Foster, John V.; Bundick, W. Thomas; Connelly, Patrick J.; Kelly, John W.; Pahle, Joseph W.; Thomas, Michael; Wichman, Keith D.; Wilson, R. Joseph

    1996-01-01

    Specifications for a flight control law are delineated in sufficient detail to support coding the control law in flight software. This control law was designed for implementation and flight test on the High-Alpha Research Vehicle (HARV), which is an F/A-18 aircraft modified to include an experimental multi-axis thrust-vectoring system and actuated nose strakes for enhanced rolling (ANSER). The control law, known as the HARV ANSER Control Law, was designed to utilize a blend of conventional aerodynamic control effectors, thrust vectoring, and actuated nose strakes to provide increased agility and good handling qualities throughout the HARV flight envelope, including angles of attack up to 70 degrees.

  5. Direct blood dry LAMP: a rapid, stable, and easy diagnostic tool for Human African Trypanosomiasis.

    PubMed

    Hayashida, Kyoko; Kajino, Kiichi; Hachaambwa, Lottie; Namangala, Boniface; Sugimoto, Chihiro

    2015-03-01

    Loop-mediated isothermal amplification (LAMP) is a rapid and sensitive tool used for the diagnosis of a variety of infectious diseases. One of the advantages of this method over the polymerase chain reaction is that DNA amplification occurs at a constant temperature, usually between 60-65°C; therefore, expensive devices are unnecessary for this step. However, LAMP still requires complicated sample preparation steps and a well-equipped laboratory to produce reliable and reproducible results, which limits its use in resource-poor laboratories in most developing countries. In this study, we made several substantial modifications to the technique to carry out on-site diagnosis of Human African Trypanosomiasis (HAT) in remote areas using LAMP. The first essential improvement was that LAMP reagents were dried and stabilized in a single tube by incorporating trehalose as a cryoprotectant to prolong shelf life at ambient temperature. The second technical improvement was achieved by simplifying the sample preparation step so that DNA or RNA could be amplified directly from detergent-lysed blood samples. With these modifications, diagnosis of HAT in local clinics or villages in endemic areas becomes a reality, which could greatly impact on the application of diagnosis not only for HAT but also for other tropical diseases. PMID:25769046

  6. Development of a nanoparticulate formulation of diminazene to treat African trypanosomiasis

    NASA Astrophysics Data System (ADS)

    Kroubi, Maya; Daulouede, Sylvie; Karembe, Hamadi; Jallouli, Youssef; Howsam, Mike; Mossalayi, Djavad; Vincendeau, Philippe; Betbeder, Didier

    2010-12-01

    There is a real need to develop new therapeutic strategies for African trypanosomiasis infections. In our study, we developed a new drug delivery system of diminazene (DMZ), a trypanocidal drug registered for veterinary use. This drug candidate presents a limited efficacy, a poor affinity for brain tissue and instability. The development of colloidal formulations based on a porous cationic nanoparticle with an oily core (70DGNP + ), has potentially two advantages: stabilization of the drug and potential targeting of the parasite. We analyzed two processes of drug loading: in process (DMZ was added during the preparation of 70DGNP + at 80 °C) and post-loading (DMZ was mixed with a 70DGNP + solution at room temperature). Poor stability of the drug was observed using the in process technique. When using the post-loading technique over 80% drug entrapment efficiency was obtained at a ratio of DMZ:phospholipids (wt:wt) < 5%. Moreover, DMZ loaded into 70DGNP + was found to be protected against oxidation and was stable for at least six months at 4 °C. Finally, in vitro tests on T.b. brucei showed an increased efficacy of DMZ loaded in 70DGNP + .

  7. Human African trypanosomiasis: pharmacological re-engagement with a neglected disease.

    PubMed

    Barrett, M P; Boykin, D W; Brun, R; Tidwell, R R

    2007-12-01

    This review discusses the challenges of chemotherapy for human African trypanosomiasis (HAT). The few drugs registered for use against the disease are unsatisfactory for a number of reasons. HAT has two stages. In stage 1 the parasites proliferate in the haemolymphatic system. In stage 2 they invade the central nervous system and brain provoking progressive neurological dysfunction leading to symptoms that include the disrupted sleep wake patterns that give HAT its more common name of sleeping sickness. Targeting drugs to the central nervous system offers many challenges. However, it is the cost of drug development for diseases like HAT, that afflict exclusively people of the world's poorest populations, that has been the principal barrier to new drug development and has led to them becoming neglected. Here we review drugs currently registered for HAT, and also discuss the few compounds progressing through clinical trials. Finally we report on new initiatives that might allow progress to be made in developing new and satisfactory drugs for this terrible disease. PMID:17618313

  8. Direct Blood Dry LAMP: A Rapid, Stable, and Easy Diagnostic Tool for Human African Trypanosomiasis

    PubMed Central

    Hayashida, Kyoko; Kajino, Kiichi; Hachaambwa, Lottie; Namangala, Boniface; Sugimoto, Chihiro

    2015-01-01

    Loop-mediated isothermal amplification (LAMP) is a rapid and sensitive tool used for the diagnosis of a variety of infectious diseases. One of the advantages of this method over the polymerase chain reaction is that DNA amplification occurs at a constant temperature, usually between 60–65°C; therefore, expensive devices are unnecessary for this step. However, LAMP still requires complicated sample preparation steps and a well-equipped laboratory to produce reliable and reproducible results, which limits its use in resource-poor laboratories in most developing countries. In this study, we made several substantial modifications to the technique to carry out on-site diagnosis of Human African Trypanosomiasis (HAT) in remote areas using LAMP. The first essential improvement was that LAMP reagents were dried and stabilized in a single tube by incorporating trehalose as a cryoprotectant to prolong shelf life at ambient temperature. The second technical improvement was achieved by simplifying the sample preparation step so that DNA or RNA could be amplified directly from detergent-lysed blood samples. With these modifications, diagnosis of HAT in local clinics or villages in endemic areas becomes a reality, which could greatly impact on the application of diagnosis not only for HAT but also for other tropical diseases. PMID:25769046

  9. Synergism between 9-deazainosine and DL-alpha-difluoromethylornithine in treatment of experimental African trypanosomiasis.

    PubMed Central

    Bacchi, C J; Berens, R L; Nathan, H C; Klein, R S; Elegbe, I A; Rao, K V; McCann, P P; Marr, J J

    1987-01-01

    Kinetoplastid hemoflagellates are sensitive to growth inhibition by various purine analogs. In this study the activities of 9-deazainosine (9-DINO), formycin B, and sinefungin were compared in experimental murine Trypanosoma brucei subsp. brucei infections, both singly and in combination with the ornithine decarboxylase inhibitor DL-alpha-difluoromethylornithine (DFMO, eflornithine). Used singly, all of the purine analogs were able to suppress an acute T. brucei subsp. brucei infection. 9-DINO and formycin B were the most active. None of the purine analogs was curative when used singly against a strain causing chronic central nervous system infection. 9-DINO was highly effective when used in combination with DFMO in curing this central nervous system infection and another more stringent experimental infection. Neither sinefungin nor formycin B was active in combination with DFMO in curing the central nervous system experimental infection. 9-DINO was metabolized to phosphorylated derivatives of 9-deazaadenosine and 9-deazaguanosine by bloodstream trypomastigotes, but not by murine erythrocyte suspensions or kidney or liver homogenates--a potential rationale for the selectivity of the analog. These studies indicate that 9-DINO is a potent, nontoxic purine analog which, in combination with DFMO, is capable of late-stage cures of African trypanosomiasis. PMID:3118799

  10. Made-to-measure malaria vector control strategies: rational design based on insecticide properties and coverage of blood resources for mosquitoes

    PubMed Central

    2014-01-01

    Eliminating malaria from highly endemic settings will require unprecedented levels of vector control. To suppress mosquito populations, vector control products targeting their blood hosts must attain high biological coverage of all available sources, rather than merely high demographic coverage of a targeted resource subset, such as humans while asleep indoors. Beyond defining biological coverage in a measurable way, the proportion of blood meals obtained from humans and the proportion of bites upon unprotected humans occurring indoors also suggest optimal target product profiles for delivering insecticides to humans or livestock. For vectors that feed only occasionally upon humans, preferred animal hosts may be optimal targets for mosquito-toxic insecticides, and vapour-phase insecticides optimized to maximize repellency, rather than toxicity, may be ideal for directly protecting people against indoor and outdoor exposure. However, for vectors that primarily feed upon people, repellent vapour-phase insecticides may be inferior to toxic ones and may undermine the impact of contact insecticides applied to human sleeping spaces, houses or clothing if combined in the same time and place. These concepts are also applicable to other mosquito-borne anthroponoses so that diverse target species could be simultaneously controlled with integrated vector management programmes. Measurements of these two crucial mosquito behavioural parameters should now be integrated into programmatically funded, longitudinal, national-scale entomological monitoring systems to inform selection of available technologies and investment in developing new ones. PMID:24739261

  11. New Support Vector Algorithms

    Microsoft Academic Search

    Bernhard Schölkopf; Alex J. Smola; Robert C. Williamson; Peter L. Bartlett

    2000-01-01

    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

  12. A benzoic acid derivative and flavokawains from Piper species as schistosomiasis vector controls.

    PubMed

    Rapado, Ludmila N; Freitas, Giovana C; Polpo, Adriano; Rojas-Cardozo, Maritza; Rincón, Javier V; Scotti, Marcus T; Kato, Massuo J; Nakano, Eliana; Yamaguchi, Lydia F

    2014-01-01

    The search of alternative compounds to control tropical diseases such as schistosomiasis has pointed to secondary metabolites derived from natural sources. Piper species are candidates in strategies to control the transmission of schistosomiasis due to their production of molluscicidal compounds. A new benzoic acid derivative and three flavokawains from Piper diospyrifolium, P. cumanense and P. gaudichaudianum displayed significant activities against Biomphalaria glabrata snails. Additionally, "in silico" studies were performed using docking assays and Molecular Interaction Fields to evaluate the physical-chemical differences among the compounds in order to characterize the observed activities of the test compounds against Biomphalaria glabrata snails. PMID:24762961

  13. Current procedures of the integrated urban vector-mosquito control as an example in Cotonou (Benin, West Africa) and Wroc?aw area (Poland).

    PubMed

    Rydzanicz, Katarzyna; Lonc, Elzbieta; Becker, Norbert

    2009-01-01

    Current strategy of Integrated Vector Management (IVM) comprises the general approach of environmentally friendly control measures. With regard to mosquitoes it includes first of all application of microbial insecticides based on Bacillus thuringiensis israelensis (Bti) and B. sphaericus (Bs) delta-endotoxins as well as the reduction of breeding habitats and natural enemy augmentation. It can be achieved thorough implementation of the interdisciplinary program, i. e., understanding of mosquito vector ecology, the appropriate vector-diseases (e. g., malariometric) measurements and training of local personnel responsible for mosquito abatement activities, as well as community involvement. Biocontrol methods as an alternative to chemical insecticides result from the sustainability development concept, growing awareness of environmental pollution and the development of insecticide-resistant strains of vector-mosquito populations in many parts of the world. Although sustainable trends are usually considered in terms of the monetary and training resources within countries, environmental concerns are actually more limiting factors for the duration of an otherwise successful vector control effort. In order to meet these new needs, increasing efforts have been made in search of and application of natural enemies, such as parasites, bacterial pathogens and predators which may control populations of insect vectors. The biological control agent based on the bacterial toxins Bti and Bs has been used in the Wroc?aw's University and Municipal Mosquito Control Programs since 1998. In West-Africa biocontrol appears to be an effective and safe tool to combat malaria in addition to bed-nets, residual indoor spraying and appropriate diagnosis and treatment of malaria parasites which are the major tools in the WHO Roll Back Malaria Program. IVM studies carried out 2005-2008 in Cotonou (Benin) as well those in Wroc?aw Irrigated Fields during the last years include the following major steps: 1. Mapping of all breeding sites in the project area and recording data in a geographical information system (GIS/relational database). All districts, streets and houses are numbered for quick reference during the operation; 2. Studying mosquito vector bionomics, migration and vectorial capacity in the project area, before, during and after the routine Bti treatments; 3. Assessment of the optimum for effective larvicide insecticide dosages at major breeding sites against the different target mosquito species; 4. Implementation of the microbial control agents in the integrated routine program. Adaptation of the application equipment to the local situation, training of the field staff, and routine treatments; 5. Conducting surveillance of vector-disease (e. g., malariometric) parameters in the control and experimental area before, during, and after the application of biocontrol agents. PMID:20209805

  14. A key component of the integrated control of vector-borne diseases such as malaria and

    E-print Network

    Read, Andrew

    for the control of locusts and grasshoppers to examine the potential for development of a biopesticide to infect mosquitoes in resting and breeding sites in residential settings. Biopesticides for locusts and grasshoppers chemical applications against locusts and grasshoppers in Africa, the international donor community sup

  15. Spray characterization of thermal fogging equipment typically used in vector control

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The generation of insecticide laden fogs provides an effective method for controlling flying insects. One of the critical factors affecting the effectiveness of a thermal fogging application is the generation of droplets that will remain aloft in the fogging cloud and moves into the area where the ...

  16. CHANGING APPROACHES TO CONTROLLING PATHOGENS IN BIOSOLIDS AND THEIR VECTOR ATTRACTIVENESS

    EPA Science Inventory

    This paper reviews the commonly employed Class A and B processes for controlling pathogens; notes how extensively they are used; and discusses issues and concerns with some of them. Processes presently being researched are also noted together with EPA's methodology for determinin...

  17. 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.

  18. Integrated control of vector-borne diseases of livestock – pyrethroids: panacea or poison?

    Microsoft Academic Search

    Mark C. Eisler; Stephen J. Torr; Paul G. Coleman; Noreen Machila; John F. Morton

    2003-01-01

    Tick- and tsetse-borne diseases cost Africa ?US$4–5 billion per year in livestock production-associated losses. The use of pyrethroid-treated cattle to control ticks and tsetse promises to be an increasingly important tool to counter this loss. However, uncontrolled use of this technology might lead to environmental damage, acaricide resistance in tick populations and a possible exacerbation of tick-borne diseases. Recent research

  19. Neuro-fuzzy based Motion Control of a Robotic Exoskeleton: Considering End-effector Force Vectors

    Microsoft Academic Search

    Kazuo Kiguchi; Mohammad Habibur Rahman; Makoto Sasaki

    2006-01-01

    To assist physically disabled, injured, and\\/or elderly persons, we have been developing a 3DOF exoskeleton robot for assisting upper-limb motion, since upper-limb motion is involved in a lot of activities of everyday life. The exoskeleton robot is mainly is controlled by the skin surface electromyogram (EMG) signals, since EMG signals of muscles directly reflect how the user intends to move.

  20. Automated intelligent manufacturing system for surface finish control in CNC milling using support vector machines

    Microsoft Academic Search

    R. Ramesh; K. S. Ravi Kumar; G. Anil

    2009-01-01

    Understanding the variations in surface finish due to machining is a non-trivial task and cannot be very easily estimated\\u000a even for a given set of machining parameters and operating conditions due to the complexity of interactions involved. In this\\u000a work, an attempt has been made to propose an automated intelligent manufacturing system for the estimation and control of\\u000a surface finish

  1. A new space vector PWM control strategy for high performance converters 

    E-print Network

    Xie, Bin

    1993-01-01

    38 41 41 42 vu CHAPTER Page 3. Simulation result B. Summary V IMPLEMENTATION OF THE PROPOSED SPACE VEC- TOR PWM WITH DSP TECHNOLOGY. . . . . . . . . . . A. Digital signal processing and control B. Selection of the DSP processor 1. System... described situations in real time and guarantee high performance characteristics in pulse width modulated rectifier and inverter systems. The computational procedure of the switching states is simple and is adaptable to implementation in modern DSP...

  2. Community-centred eco-bio-social approach to control dengue vectors: an intervention study from Myanmar

    PubMed Central

    Wai, Khin Thet; Htun, Pe Than; Oo, Tin; Myint, Hla; Lin, Zaw; Kroeger, Axel; Sommerfeld, Johannes; Petzold, Max

    2012-01-01

    Objectives To build up and analyse the feasibility, process, and effectiveness of a partnership-driven ecosystem management intervention in reducing dengue vector breeding and constructing sustainable partnerships among multiple stakeholders. Methods A community-based intervention study was conducted from May 2009 to January 2010 in Yangon city. Six high-risk and six low-risk clusters were randomized and allocated as intervention and routine service areas, respectively. For each cluster, 100 households were covered. Bi-monthly entomological evaluations (i.e. larval and pupal surveys) and household acceptability surveys at the end of 6-month intervention period were conducted, supplemented by qualitative evaluations. Intervention description The strategies included eco-friendly multi-stakeholder partner groups (Thingaha) and ward-based volunteers, informed decision-making of householders, followed by integrated vector management approach. Findings Pupae per person index (PPI) decreased at the last evaluation by 5.7% (0.35–0.33) in high-risk clusters. But in low-risk clusters, PPI remarkably decreased by 63.6% (0.33–0.12). In routine service area, PPI also decreased due to availability of Temephos after Cyclone Nargis. As for total number of pupae in all containers, when compared to evaluation 1, there was a reduction of 18.6% in evaluation 2 and 44.1% in evaluation 3 in intervention area. However, in routine service area, more reduction was observed. All intervention tools were found as acceptable, being feasible to implement by multi-stakeholder partner groups. Conclusions The efficacy of community-controlled partnership-driven interventions was found to be superior to the vertical approach in terms of sustainability and community empowerment. PMID:23318238

  3. Modeling and space vector control of a novel multilevel matrix converter for variable-speed wind power generators

    NASA Astrophysics Data System (ADS)

    Al-Naseem, Osama Abdulrahman

    A novel multilevel matrix converter is developed to efficiently transfer energy between a three-phase variable-speed generator of a wind turbine and a three-phase ac utility network. Optimizing the energy transfer efficiency at light load is critical in variable-speed wind generators. Laboratory experiment suggests that converter efficiency at light load may be increased via soft-switching and multilevel switching techniques. The new converter includes the advantages of multilevel converters, such as reduced harmonic content, increased power handling capability without additional switching loss, and high efficiency at low machine voltages. It also features the characteristics of conventional matrix converters, such as space vector control and improved efficiency via auxiliary resonant commutation soft-switching techniques. Similar to a conventional matrix converter, the novel multilevel matrix converter uses a nine-switch matrix with four-quadrant switches to connect input phases at one side of the converter with output phases at the other side of the converter. However, the switches of the new converter are configured differently from those used in the conventional matrix converter. Each switch of the new converter is a cell that resembles a full-bridge inverter topology and can assume three voltage levels while used. Semiconductor devices in a switch cell are always clamped to a known constant do voltage of a capacitor. This is a typical characteristic of multilevel converters where device voltage stresses are reduced by clamping the main transistor voltages to low levels. With reduced voltage stresses, switching frequency can be increased to allow for reduced size of filter magnetics. Unlike conventional matrix converter, the multilevel matrix converter uses inductors on both input and output sides of the converter. This symmetry allows for both step up and step down operations. Each switch cell features double the power handling capability compared to the four-quadrant switches used in a conventional matrix converter. This increase in power handling capability is due to the doubling of the number of devices in a multilevel matrix converter switch cell. Scaling up the power handling capability is accomplished by cascading more than one switch cell per branch. Control of the new converter is achieved through space vector modulation in which three-phase ac voltages are transformed to the d-q reference frame and compared with a set of space vectors prior to modulation. Since it has 19683 different switching combinations, control can be difficult and complex. Nevertheless, the multilevel matrix converter has been modeled and controlled through simulation. Simulation results show the possibility of operating the converter to produce the desired voltage waveforms with universal input and output power factors and maintain constant capacitor voltages simultaneously. Also in this dissertation is the derivation of an analytical averaged equivalent circuit model of a PWM converter. This model reveals how dominant loss mechanisms vary with converter operating point. The model is based on the operational characteristics of power diodes and IGBTs. Laboratory experiments support the derived model and confirm that IGBT current tailing and diode reverse-recovery are indeed the most critical losses in a PWM converter. These losses are more significant at light load, hence reducing the energy capture capability of converters used in wind generation. The results suggest that multilevel conversion, which has been employed in the novel multilevel matrix converter, could improve the low-wind converter efficiency.

  4. Exploring new thermal fog and ultra-low volume technologies to improve indoor control of the dengue vector, Aedes aegypti (Diptera: Culicidae).

    PubMed

    Harwood, James F; Farooq, Muhammad; Richardson, Alec G; Doud, Carl W; Putnam, John L; Szumlas, Daniel E; Richardson, Jason H

    2014-07-01

    Control of the mosquito vector, Aedes aegypti (L.), inside human habitations must be performed quickly and efficiently to reduce the risk of transmission during dengue outbreaks. As part of abroad study to assess the efficacy of dengue vector control tools for the U.S. Military, two pesticide delivery systems (ultra-low volume [ULV] and thermal fog) were evaluated for their ability to provide immediate control of Ae. aegypti mosquitoes with a contact insecticide inside simulated urban structures. An insect growth regulator was also applied to determine how well each sprayer delivered lethal doses of active ingredient to indoor water containers for pupal control. Mortality of caged Ae. aegypti, pesticide droplet size, and droplet deposition were recorded after applications. In addition, larval and pupal mortality was measured from treated water samples for 4 wk after the applications. The ULV and the thermal fogger performed equally well in delivering lethal doses of adulticide throughout the structures. The ULV resulted in greater larval mortality and adult emergence inhibition in the water containers for a longer period than the thermal fogger. Therefore, the ULV technology is expected to be a better tool for sustained vector suppression when combined with an effective insect growth regulator. However, during a dengue outbreak, either delivery system should provide an immediate knockdown of vector populations that may lower the risk of infection and allow other suppression strategies to be implemented. PMID:25118418

  5. Vector control scheme of synchronous reluctance motor considering iron core loss

    SciTech Connect

    Kim, J.C.; Lee, J.H.; Jung, I.S.; Hyun, D.S. [Hanyang Univ., Seoul (Korea, Republic of). Dept. of Electrical Engineering

    1998-09-01

    This paper proposes the method, in the Synchronous Reluctance Motor (SynRM), which selects appropriate stator d,q-axis current component combination (flux current, torque current) 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 proposed method and the characteristics analysis is performed under the effect of saturation and iron loss. The computer simulation and experimental results show the propriety of the proposed method.

  6. Human antibody response to Aedes albopictus salivary proteins: a potential biomarker to evaluate the efficacy of vector control in an area of Chikungunya and Dengue Virus transmission.

    PubMed

    Doucoure, Souleymane; Mouchet, François; Cornelie, Sylvie; Drame, Papa Makhtar; D'Ortenzio, Eric; DeHecq, Jean Sébastien; Remoue, Franck

    2014-01-01

    Aedes borne viruses represent public health problems in southern countries and threat to emerge in the developed world. Their control is currently based on vector population control. Much effort is being devoted to develop new tools to control such arbovirus. Recent findings suggest that the evaluation of human antibody (Ab) response to arthropod salivary proteins is relevant to measuring the level of human exposure to mosquito bites. Using an immunoepidemiological approach, the present study aimed to assess the usefulness of the salivary biomarker for measuring the efficacy of Ae. albopictus control strategies in La Reunion urban area. The antisaliva Ab response of adult humans exposed to Ae. albopictus was evaluated before and after vector control measures. Our results showed a significant correlation between antisaliva Ab response and the level of exposure to vectors bites. The decrease of Ae. albopictus density has been detected by this biomarker two weeks after the implementation of control measures, suggesting its potential usefulness for evaluating control strategies in a short time period. The identification of species specific salivary proteins/peptides should improve the use of this biomarker. PMID:24822216

  7. Re-adhesion control of electric motor coach based on disturbance observer and sensor-less vector control

    Microsoft Academic Search

    Satoshi Kadowaki; Kiyoshi Ohishi; Ichiro Miyashita; Shinobu Yasukawa

    2002-01-01

    When the adhesion force coefficient between rail and driving wheel decreases, the electric motor coach has slip phenomena. We have already proposed the anti-slip re-adhesion control system based on a disturbance observer. This system has the fine torque response for one driving wheel driven by one inverter-fed induction motor. However, the bogie of an electric motor coach has four driving

  8. Incorporating Scale Dependence in Disease Burden Estimates: The Case of Human African Trypanosomiasis in Uganda

    PubMed Central

    Hackett, Finola; Berrang Ford, Lea; Fèvre, Eric; Simarro, Pere

    2014-01-01

    Background The WHO has established the disability-adjusted life year (DALY) as a metric for measuring the burden of human disease and injury globally. However, most DALY estimates have been calculated as national totals. We mapped spatial variation in the burden of human African trypanosomiasis (HAT) in Uganda for the years 2000–2009. This represents the first geographically delimited estimation of HAT disease burden at the sub-country scale. Methodology/Principal Findings Disability-adjusted life-year (DALY) totals for HAT were estimated based on modelled age and mortality distributions, mapped using Geographic Information Systems (GIS) software, and summarised by parish and district. While the national total burden of HAT is low relative to other conditions, high-impact districts in Uganda had DALY rates comparable to the national burden rates for major infectious diseases. The calculated average national DALY rate for 2000–2009 was 486.3 DALYs/100 000 persons/year, whereas three districts afflicted by rhodesiense HAT in southeastern Uganda had burden rates above 5000 DALYs/100 000 persons/year, comparable to national GBD 2004 average burden rates for malaria and HIV/AIDS. Conclusions/Significance These results provide updated and improved estimates of HAT burden across Uganda, taking into account sensitivity to under-reporting. Our results highlight the critical importance of spatial scale in disease burden analyses. National aggregations of disease burden have resulted in an implied bias against highly focal diseases for which geographically targeted interventions may be feasible and cost-effective. This has significant implications for the use of DALY estimates to prioritize disease interventions and inform cost-benefit analyses. PMID:24551264

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

    PubMed Central

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

    2008-01-01

    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 requirement for cell survival. Since the growth arrest after RNA interference appeared to be more profound for T. brucei GSK-3 “short” (Tb10.161.3140) than for T. brucei GSK-3 “long” (Tb927.7.2420), we focused on T. brucei GSK-3 short for further studies. T. brucei GSK-3 short with an N-terminal maltose-binding protein fusion was cloned, expressed, and purified in a functional form. The potency of a GSK-3-focused inhibitor library against the recombinant enzyme of T. brucei GSK-3 short, as well as bloodstream-form parasites, was evaluated with the aim of determining if compounds that inhibit enzyme activity could also block the parasites' growth and proliferation. Among the compounds active against the cell, there was an excellent correlation between activity inhibiting the T. brucei GSK-3 short enzyme and the inhibition of T. brucei growth. Thus, there is reasonable genetic and chemical validation of GSK-3 short as a drug target for T. brucei. Finally, selective inhibition may be required for therapy targeting the GSK-3 enzyme, and a molecular model of the T. brucei GSK-3 short enzyme suggests that compounds that selectively inhibit T. brucei GSK-3 short over the human GSK-3 enzymes can be found. PMID:18644955

  10. Monitoring the Progress towards the Elimination of Gambiense Human African Trypanosomiasis

    PubMed Central

    Franco, José R.; Paone, Massimo; Diarra, Abdoulaye; Priotto, Gerardo; Mattioli, Raffaele C.; Jannin, Jean G.

    2015-01-01

    Background Over the last few years, momentum has gathered around the feasibility and opportunity of eliminating gambiense human African trypanosomiasis (g-HAT). Under the leadership of the World Health Organization (WHO), a large coalition of stakeholders is now committed to achieving this goal. A roadmap has been laid out, and indicators and milestones have been defined to monitor the progress of the elimination of g-HAT as a public health problem by 2020. Subsequently, a more ambitious objective was set for 2030: to stop disease transmission. This paper provides a situational update to 2012 for a number of indicators of elimination: number of cases annually reported, geographic distribution of the disease and areas and populations at different levels of risk. Results Comparing the 5-year periods 2003-2007 and 2008-2012, the area at high or very high risk of g-HAT shrank by 60%, while the area at moderate risk decreased by 22%. These are the areas where g-HAT is still to be considered a public health problem (i.e. > 1 HAT reported case per 10,000 people per annum). This contraction of at-risk areas corresponds to a reduction of 57% for the population at high or very high risk (from 4.1 to 1.8 million), and 20% for moderate risk (from 14.0 to 11.3 million). Discussion Improved data completeness and accuracy of the Atlas of HAT enhanced our capacity to monitor the progress towards the elimination of g-HAT. The trends in the selected indicators suggest that, in recent years, progress has been steady and in line with the elimination goal laid out in the WHO roadmap on neglected tropical diseases. PMID:26056823

  11. Melarsoprol cyclodextrin inclusion complexes as promising oral candidates for the treatment of human African trypanosomiasis.

    PubMed

    Rodgers, Jean; Jones, Amy; Gibaud, Stéphane; Bradley, Barbara; McCabe, Christopher; Barrett, Michael P; Gettinby, George; Kennedy, Peter G E

    2011-09-01

    Human African trypanosomiasis (HAT), or sleeping sickness, results from infection with the protozoan parasites Trypanosoma brucei (T. b.) gambiense or T. b. rhodesiense and is invariably fatal if untreated. There are 60 million people at risk from the disease throughout sub-Saharan Africa. The infection progresses from the haemolymphatic stage where parasites invade the blood, lymphatics and peripheral organs, to the late encephalitic stage where they enter the central nervous system (CNS) to cause serious neurological disease. The trivalent arsenical drug melarsoprol (Arsobal) is the only currently available treatment for CNS-stage T. b. rhodesiense infection. However, it must be administered intravenously due to the presence of propylene glycol solvent and is associated with numerous adverse reactions. A severe post-treatment reactive encephalopathy occurs in about 10% of treated patients, half of whom die. Thus melarsoprol kills 5% of all patients receiving it. Cyclodextrins have been used to improve the solubility and reduce the toxicity of a wide variety of drugs. We therefore investigated two melarsoprol cyclodextrin inclusion complexes; melarsoprol hydroxypropyl-?-cyclodextrin and melarsoprol randomly-methylated-?-cyclodextrin. We found that these compounds retain trypanocidal properties in vitro and cure CNS-stage murine infections when delivered orally, once per day for 7-days, at a dosage of 0.05 mmol/kg. No overt signs of toxicity were detected. Parasite load within the brain was rapidly reduced following treatment onset and magnetic resonance imaging showed restoration of normal blood-brain barrier integrity on completion of chemotherapy. These findings strongly suggest that complexed melarsoprol could be employed as an oral treatment for CNS-stage HAT, delivering considerable improvements over current parenteral chemotherapy. PMID:21909447

  12. Stable Expression of Lentiviral Antigens by Quality-Controlled Recombinant Mycobacterium bovis BCG Vectors.

    PubMed

    Hart, Bryan E; Asrican, Rose; Lim, So-Yon; Sixsmith, Jaimie D; Lukose, Regy; Souther, Sommer J R; Rayasam, Swati D G; Saelens, Joseph W; Chen, Ching-Ju; Seay, Sarah A; Berney-Meyer, Linda; Magtanong, Leslie; Vermeul, Kim; Pajanirassa, Priyadharshini; Jimenez, Amanda E; Ng, Tony W; Tobin, David M; Porcelli, Steven A; Larsen, Michelle H; Schmitz, Joern E; Haynes, Barton F; Jacobs, William R; Lee, Sunhee; Frothingham, Richard

    2015-07-01

    The well-established safety profile of the tuberculosis vaccine strain, Mycobacterium bovis bacille Calmette-Guérin (BCG), makes it an attractive vehicle for heterologous expression of antigens from clinically relevant pathogens. However, successful generation of recombinant BCG strains possessing consistent insert expression has encountered challenges in stability. Here, we describe a method for the development of large recombinant BCG accession lots which stably express the lentiviral antigens, human immunodeficiency virus (HIV) gp120 and simian immunodeficiency virus (SIV) Gag, using selectable leucine auxotrophic complementation. Successful establishment of vaccine stability stems from stringent quality control criteria which not only screen for highly stable complemented BCG ?leuCD transformants but also thoroughly characterize postproduction quality. These parameters include consistent production of correctly sized antigen, retention of sequence-pure plasmid DNA, freeze-thaw recovery, enumeration of CFU, and assessment of cellular aggregates. Importantly, these quality assurance procedures were indicative of overall vaccine stability, were predictive for successful antigen expression in subsequent passaging both in vitro and in vivo, and correlated with induction of immune responses in murine models. This study has yielded a quality-controlled BCG ?leuCD vaccine expressing HIV gp120 that retained stable full-length expression after 10(24)-fold amplification in vitro and following 60 days of growth in mice. A second vaccine lot expressed full-length SIV Gag for >10(68)-fold amplification in vitro and induced potent antigen-specific T cell populations in vaccinated mice. Production of large, well-defined recombinant BCG ?leuCD lots can allow confidence that vaccine materials for immunogenicity and protection studies are not negatively affected by instability or differences between freshly grown production batches. PMID:25924766

  13. Control of Pyrethroid-Resistant Chagas Disease Vectors with Entomopathogenic Fungi

    PubMed Central

    Pedrini, Nicolás; Mijailovsky, Sergio J.; Girotti, Juan R.; Stariolo, Raúl; Cardozo, Rubén M.; Gentile, Alberto; Juárez, M. Patricia

    2009-01-01

    Background Triatoma infestans-mediated transmission of Tripanosoma cruzi, the causative agent of Chagas disease, remains as a major health issue in southern South America. Key factors of T. infestans prevalence in specific areas of the geographic Gran Chaco region—which extends through northern Argentina, Bolivia, and Paraguay—are both recurrent reinfestations after insecticide spraying and emerging pyrethroid-resistance over the past ten years. Among alternative control tools, the pathogenicity of entomopathogenic fungi against triatomines is already known; furthermore, these fungi have the ability to fully degrade hydrocarbons from T. infestans cuticle and to utilize them as fuel and for incorporation into cellular components. Methodology and Findings Here we provide evidence of resistance-related cuticle differences; capillary gas chromatography coupled to mass spectrometry analyses revealed that pyrethroid-resistant bugs have significantly larger amounts of surface hydrocarbons, peaking 56.2±6.4% higher than susceptible specimens. Also, a thicker cuticle was detected by scanning electron microscopy (32.1±5.9 µm and 17.8±5.4 µm for pyrethroid-resistant and pyrethroid-susceptible, respectively). In laboratory bioassays, we showed that the virulence of the entomopathogenic fungi Beauveria bassiana against T. infestans was significantly enhanced after fungal adaptation to grow on a medium containing insect-like hydrocarbons as the carbon source, regardless of bug susceptibility to pyrethroids. We designed an attraction-infection trap based on manipulating T. infestans behavior in order to facilitate close contact with B. bassiana. Field assays performed in rural village houses infested with pyrethroid-resistant insects showed 52.4% bug mortality. Using available mathematical models, we predicted that further fungal applications could eventually halt infection transmission. Conclusions This low cost, low tech, ecologically friendly methodology could help in controlling the spread of pyrethroid-resistant bugs. PMID:19434231

  14. Depression and the Sense of Control: Aging Vectors, Trajectories and Trends*

    PubMed Central

    Mirowsky, John

    2013-01-01

    Adulthood trajectories of outcomes such as depression and the sense of control measure aspects of the human condition that Americans may view as objects of change. Social science should provide information on that progress, or its absence. Whether these trajectories change their shape, and how and why if they do, is important theoretically too. A range of birth cohorts coexist in time, place, and social relationship. Each cohort, as it goes through adulthood, follows in aggregate a path left by older ones, reshaping that path as it goes. The shapes of the trajectories, and the trends reshaping them, represent two inseparable aspects of the same phenomenon. This report describes methods for mapping aging trajectories and inter-cohort trends, using linear latent-growth models of relatively brief followup data (six years in the examples). It reviews shared research ideals that led to the model: put theory into modeling, go where the data lead, use what you have, go beyond where you have been, and risk being precisely wrong. PMID:24311752

  15. Fascioliasis Control: In Vivo and In Vitro Phytotherapy of Vector Snail to Kill Fasciola Larva

    PubMed Central

    Sunita, Kumari; Singh, D. K.

    2011-01-01

    Snail is one of the important components of an aquatic ecosystem, it acts as intermediate host of Fasciola species. Control of snail population below a certain threshold level is one of the important methods in the campaign to reduce the incidence of fascioliasis. Life cycle of the parasite can be interrupted by killing the snail or Fasciola larva redia and cercaria in the snail body. In vivo and in vitro toxicity of the plant products and their active component such as citral, ferulic acid, umbelliferone, azadirachtin, and allicin against larva of Fasciola in infected snail Lymnaea acuminata were tested. Mortality of larvae were observed at 2?h, 4?h, 6?h, and 8?h, of treatment. In in vivo treatment, azadirachtin caused highest mortality in redia and cercaria larva (8?h, LC50 0.11, and 0.05?mg/L) whereas in in vitro condition allicin was highly toxic against redia and cercaria (8?h, LC50 0.01, and 0.009?mg/L). Toxicity of citral was lowest against redia and cercaria larva. PMID:22132306

  16. Spray characterization of thermal fogging equipment typically used in vector control.

    PubMed

    Hoffmann, W C; Walker, T W; Fritz, B K; Gwinn, T; Smith, V L; Szumlas, D; Quinn, B; Lan, Y; Huang, Y; Sykes, D

    2008-12-01

    Droplet size spectra from different sprayers used to generate insecticide-laden fogs for controlling flying insects were measured by a laser diffraction instrument and Teflon-coated slides. The objectives of this work were to present not only information on spray-system droplet size generated by different sprayers, but to compare methodologies by which other similar systems can be evaluated and give applicators sprayer-system performance data. Data from 45 replicated spray tests, comprising 11 sprayers and 5 pesticides, showed a wide range in the droplet size spectra produced. The volume median diameter measurements ranged from 2.6 to 75.5 microm for diesel-diluted sprays and from 27.9 to 59.9 microm for water-diluted sprays. Similarly, the percent volume <20 microm ranged between 12.0-100% and 8.5-30.7%, for diesel- and water-diluted sprays, respectively. The droplet sizes measured by the swinging slide and laser diffraction methods were not consistent. The information presented aids users in sprayer selection and operation to produce the specific droplet size spectra required for a particular application. PMID:19181064

  17. Natural polymer-based magnetic hydrogels: Potential vectors for remote-controlled drug release.

    PubMed

    Paulino, Alexandre T; Pereira, Antonio G B; Fajardo, André R; Erickson, Kristin; Kipper, Matt J; Muniz, Edvani C; Belfiore, Laurence A; Tambourgi, Elias B

    2012-10-15

    The preparation and characterization of natural polymer-based hydrogels that contain 50-nm diameter magnetite (i.e., FeO:Fe(2)O(3)) nanoparticles are described herein. Fourier-transform infrared spectroscopy (FTIR) analysis confirmed the efficiency of the polysaccharide-modifying process. Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and compressive moduli demostrate that the presence of magnetite improves thermal and mechanical resistance. Transient diffusion of water in magnetic hydrogels was analyzed via boundary layer mass transfer across an expaning interface, and the degree of swelling of these polysaccharide hydrogels decreases in the presence of magnetite, with no variation in the binary diffusion mechanism. The absence of hysteresis loops and coercivity observed via magnetometry suggests that magnetic hydrogels are useful for remote-controlled drug release, as demonstrated by magnetic-field-induced release of curcumin. Experiments reveal that magnetic hydrogels with greater magnetic susceptibility have the potential to release larger concentrations of drugs from the hydrogel network. PMID:22939334

  18. Human Antibody Responses to the Anopheles Salivary gSG6-P1 Peptide: A Novel Tool for Evaluating the Efficacy of ITNs in Malaria Vector Control

    PubMed Central

    Drame, Papa Makhtar; Poinsignon, Anne; Besnard, Patrick; Cornelie, Sylvie; Le Mire, Jacques; Toto, Jean-Claude; Foumane, Vincent; Dos-Santos, Maria Adelaide; Sembène, Mbacké; Fortes, Filomeno; Simondon, Francois; Carnevale, Pierre; Remoue, Franck

    2010-01-01

    To optimize malaria control, WHO has prioritised the need for new indicators to evaluate the efficacy of malaria vector control strategies. The gSG6-P1 peptide from gSG6 protein of Anopheles gambiae salivary glands was previously designed as a specific salivary sequence of malaria vector species. It was shown that the quantification of human antibody (Ab) responses to Anopheles salivary proteins in general and especially to the gSG6-P1 peptide was a pertinent biomarker of human exposure to Anopheles. The present objective was to validate this indicator in the evaluation of the efficacy of Insecticide Treated Nets (ITNs). A longitudinal evaluation, including parasitological, entomological and immunological assessments, was conducted on children and adults from a malaria-endemic area before and after the introduction of ITNs. Significant decrease of anti-gSG6-P1 IgG response was observed just after the efficient ITNs use. Interestingly, specific IgG Ab level was especially pertinent to evaluate a short-time period of ITNs efficacy and at individual level. However, specific IgG rose back up within four months as correct ITN use waned. IgG responses to one salivary peptide could constitute a reliable biomarker for the evaluation of ITN efficacy, at short- and long-term use, and provide a valuable tool in malaria vector control based on a real measurement of human-vector contact. PMID:21179476

  19. Maggots as potential vector for pathogen transmission and consequences for infection control in waste management

    PubMed Central

    Daeschlein, Georg; Reese, Kevin; Napp, Matthias; Spitzmueller, Romy; Hinz, Peter; Juenger, Michael; Kramer, Axel

    2015-01-01

    Background and aims: Debridement therapy with sterile bred larvae in non-healing wounds is a widely accepted safe and efficient treatment modality. However, during application in the contaminated wound bed microbial contamination with potential microbial pathogen spread after escape from the wound or after unreliable disposal procedure may happen, particularly in the case of not using bio-bags. The aims of this work were first to investigate the release of ingested bacteria into the environment by maggots and second to examine the common practice of freezing the maggots after use and/or disposal in trash-bags. Potential methods for hygienic safe disposal of used maggots should be deduced. Methods: First, Maggots were contaminated with S. aureus by allowing them to crawl over an agar surface completely covered with bacterial growth over 24 h at 37°C. After external disinfection maggots were transferred onto sterile Columbia agar plates and shedding of S. aureus was visualized. Second, maggots were frozen at –20°C for 1, 2, 5, 10, 30, and 60 min. After exposure, the larvae were transferred onto Columbia blood agar with consecutive incubation at 37°C over 48 h. The larvae were analyzed visually for mobility and eating activities. The frozen bodies of dead larvae were examined for viable bacteria. Results: We could demonstrate that maggots release formerly ingested pathogens (S. aureus). Freezing at –20°C for at least 60 min was able to kill all maggots, however the contaminant bacteria inside could survive. Conclusion: Since freezing is apparently able to kill maggots but not to reliabely inactivate the ingested bacterial pathogens, we recommend the disposal of free-range larvae in screw cap vials after use to achieve full hygienic control.

  20. A lentiviral vector with expression controlled by E2F-1: A potential tool for the study and treatment of proliferative diseases

    SciTech Connect

    Strauss, Bryan E. [Viral Vector Group, Laboratory of Genetics and Molecular Cardiology/LIM-13, University of Sao Paulo School of Medicine (Brazil) and Program in Biotechnology, University of Sao Paulo (Brazil) and Instituto do Milenio Rede de Terapia Genica, MCT (Brazil)]. E-mail: bstrauss@usp.br; Patricio, Juliana Rotelli [Viral Vector Group, Laboratory of Genetics and Molecular Cardiology/LIM-13, University of Sao Paulo School of Medicine (Brazil); Program in Biotechnology, University of Sao Paulo (Brazil); Instituto do Milenio Rede de Terapia Genica, MCT (Brazil); Vieira de Carvalho, Anna Carolina [Viral Vector Group, Laboratory of Genetics and Molecular Cardiology/LIM-13, University of Sao Paulo School of Medicine (Brazil); Program in Biotechnology, University of Sao Paulo (Brazil); Instituto do Milenio Rede de Terapia Genica, MCT (Brazil); Bajgelman, Marcio C. [Viral Vector Group, Laboratory of Genetics and Molecular Cardiology/LIM-13, University of Sao Paulo School of Medicine (Brazil); Program in Biotechnology, University of Sao Paulo (Brazil); Instituto do Milenio Rede de Terapia Genica, MCT (Brazil)

    2006-10-06

    We have constructed a lentiviral vector with expression limited to cells presenting active E2F-1 protein, a potential advantage for gene therapy of proliferative diseases. For the FE2FLW vector, the promoter region of the human E2F-1 gene was utilized to drive expression of luciferase cDNA, included as a reporter of viral expression. Primary, immortalized, and transformed cells were transduced with the FE2FLW vector and cell cycle alterations were induced with serum starvation/replacement, contact inhibition or drug treatment, revealing cell cycle-dependent changes in reporter activity. Forced E2F-1 expression, but not E2F-2 or E2F-3, increased reporter activity, indicating a major role for this factor in controlling expression from the FE2FLW virus. We show the utility of this vector as a reporter of E2F-1 and proliferation-dependent cellular alterations upon cytotoxic/cytostatic treatment, such as the introduction of tumor suppressor genes. We propose that the FE2FLW vector may be a starting point for the development of gene therapy strategies for proliferative diseases, such as cancer or restinosis.

  1. Effectiveness and feasibility of long-lasting insecticide-treated curtains and water container covers for dengue vector control in Colombia: a cluster randomised trial

    PubMed Central

    Quintero, Juliana; García-Betancourt, Tatiana; Cortés, Sebastian; García, Diana; Alcalá, Lucas; González-Uribe, Catalina; Brochero, Helena; Carrasquilla, Gabriel

    2015-01-01

    Background Long-lasting insecticide-treated net (LLIN) window and door curtains alone or in combination with LLIN water container covers were analysed regarding effectiveness in reducing dengue vector density, and feasibility of the intervention. Methods A cluster randomised trial was conducted in an urban area of Colombia comparing 10 randomly selected control and 10 intervention clusters. In control clusters, routine vector control activities were performed. The intervention delivered first, LLIN curtains (from July to August 2013) and secondly, water container covers (from October to March 2014). Cross-sectional entomological surveys were carried out at baseline (February 2013 to June 2013), 9 weeks after the first intervention (August to October 2013), and 4–6 weeks after the second intervention (March to April 2014). Results Curtains were installed in 922 households and water container covers in 303 households. The Breteau index (BI) fell from 14 to 6 in the intervention group and from 8 to 5 in the control group. The additional intervention with LLIN covers for water containers showed a significant reduction in pupae per person index (PPI) (p=0.01). In the intervention group, the PPI index showed a clear decline of 71% compared with 25% in the control group. Costs were high but options for cost savings were identified. Conclusions Short term impact evaluation indicates that the intervention package can reduce dengue vector density but sustained effect will depend on multiple factors. PMID:25604762

  2. The Anopheles gambiae cE5 salivary protein: a sensitive biomarker to evaluate the efficacy of insecticide-treated nets in malaria vector control.

    PubMed

    Marie, Alexandra; Ronca, Raffaele; Poinsignon, Anne; Lombardo, Fabrizio; Drame, Papa M; Cornelie, Sylvie; Besnard, Patrick; Le Mire, Jacques; Fiorentino, Gabriella; Fortes, Filomeno; Carnevale, Pierre; Remoue, Franck; Arcà, Bruno

    2015-06-01

    Evaluation of vector control is crucial for improving malaria containment and, according to World Health Organization, new complementary indicators would be very valuable. In this study the IgG response to the Anopheles-specific cE5 salivary protein was tested as a tool to evaluate the efficacy of insecticide-treated nets in reducing human exposure to malaria vectors. Sera collected during a longitudinal study carried out in Angola, and including entomological and parasitological data, were used to assess the IgG response to the Anopheles gambiae cE5 in both children and adults, before and after the application of insecticide-treated nets. Seasonal fluctuation of specific IgG antibody levels according to exposure was only found in children (up to ?14 years old) whose anti-cE5 IgG response dropped after bed nets installation. These results were fully consistent with previous findings obtained with the same set of sera and indicating a substantial reduction of human-vector contact shortly after nets implementation. Overall, children IgG response to the cE5 protein appeared a very sensitive biomarker, which allowed for the detection of even weak exposure to Anopheles bites, indicating it may represent a reliable additional tool to evaluate the efficacy of vector control interventions. PMID:25637950

  3. Insect vector transmission assays.

    PubMed

    Bosco, Domenico; Tedeschi, Rosemarie

    2013-01-01

    Phytoplasmas are transmitted in a persistent propagative manner by phloem-feeding vectors belonging to the order Hemiptera, suborder Homoptera. Following acquisition from the infected source plant, there is a latent period before the vector can transmit, so transmission assays consist of three basic steps: acquisition, latency, and inoculation. More than 90 vector species (plant-, leafhoppers, and psyllids) have been discovered so far but many others are still undiscovered, and their role in spreading economically important crop diseases is neglected. Therefore, screening for vectors is an essential step in developing rational control strategies targeted against the actual vectors for phytoplasma-associated diseases. The mere detection of a phytoplasma in an insect does not imply that the insect is a vector; a transmission assay is required to provide conclusive evidence. Transmission experiments can be carried out using insects from phytoplasma-free laboratory colonies or field-collections. Moreover, transmission assays can be performed by feeding vectors on an artificial diet through Parafilm(®), after which phytoplasmas can be detected in the sucrose feeding medium by PCR. Transmission trials involve the use of different techniques according to the biology of the different vector species; planthoppers, leafhoppers, and psyllids. PMID:22987407

  4. Ecological links between water storage behaviors and Aedes aegypti production: implications for dengue vector control in variable climates.

    PubMed

    Padmanabha, H; Soto, E; Mosquera, M; Lord, C C; Lounibos, L P

    2010-08-01

    Understanding linkages between household behavior and Aedes aegypti (L.) larval ecology is essential for community-based dengue mitigation. Here we associate water storage behaviors with the rate of A. aegypti pupal production in three dengue-endemic Colombian cities with different mean temperatures. Qualitative, semi-structured interviews and pupal counts were conducted over a 7-15-day period in 235 households containing a water storage vessel infested with larvae. Emptying vessels more often than every 7 days strongly reduced pupal production in all three cities. Emptying every 7-15 days reduced production by a similar magnitude as emptying <7 days in Armenia (21.9 degrees C), has a threefold smaller reduction as compared to <7 days in Bucaramanga (23.9 degrees C), and did not reduce production in Barranquilla (29.0 degrees C). Lidding vessels reduced mosquito production and was most feasible in Barranquilla because of container structure. Vessel emptying strongly correlated with usage in Barranquilla, where many households stored water in case of interruptions in piped service rather than for regular use. In the cooler cities, >90% of households regularly used stored water for washing clothes, generating a weaker correlation between emptying and usage. Emptying was less frequent in the households surveyed in the dry season in all three cities. These results show that A. aegypti production and human behaviors are coupled in a temperature-dependent manner. In addition to biological effects on aquatic stages, climate change may impact A. aegypti production through human behavioral adaptations. Vector control programs should account for geographic variation in temperature and water usage behaviors in designing targeted interventions. PMID:20358255

  5. Potential of contact insecticides to control Xyleborus glabratus (Coleoptera: Curculionidae), a vector of laurel wilt disease in avocados.

    PubMed

    Carrillo, Daniel; Crane, Jonathan H; Peña, Jorge E

    2013-12-01

    Xyleborus glabratus Eichhoff (Coleoptera: Curculionidae: Scolytinae) is an invasive ambrosia beetle that vectors laurel wilt, a new disease that threatens avocado and other species in the Lauraceae Family. The lethal concentrations (LC50 & 90) of nine commercial insecticides to X. glabratus were determined by using a bolt-dip bioassay. Different formulations of bifenthrin, permethrin, fenpropathrin, z-cypermethrin + bifenthrin, 1-cyhalothrin + thiamethoxam, malathion, chlorpyrifos, carbaryl, and methomyl were tested. Four concentrations of each insecticide were tested (0.5, 0.1, 0.03, and 0.01 of the label rate) and with water as a control. Beetles were exposed to treated bolts and mortality registered 48 h later. After 2 wk, bolts were destructively sampled to determine the number of beetles that constructed galleries and were alive inside the wood. Probit analysis was used to determine the LC50 & 90. Six pesticides were applied directly to the trunk and limbs of avocado trees in a commercial grove. Limbs of treated trees were cut weekly after the application and exposed to X. glabratus to determine the number of beetles boring into the logs. The toxicity of pesticides to X. glabratus was greatly reduced 2 wk after application. Among the tested pesticides, malathion and z-cypermethrin + bifenthrin provided the best suppression of X. glabratus. Among the insecticides registered for use in avocado, fenpropathrin and malathion were the most effective in protecting trees from attack by X. glabratus. Other pesticides that are currently not registered for use in avocados could be useful for managing this ambrosia beetle. PMID:24498726

  6. Some experiences with Krylov vectors and Lanczos vectors

    NASA Technical Reports Server (NTRS)

    Craig, Roy R., Jr.; Su, Tzu-Jeng; Kim, Hyoung M.

    1993-01-01

    This paper illustrates the use of Krylov vectors and Lanczos vectors for reduced-order modeling in structural dynamics and for control of flexible structures. Krylov vectors and Lanczos vectors are defined and illustrated, and several applications that have been under study at The University of Texas at Austin are reviewed: model reduction for undamped structural dynamics systems, component mode synthesis using Krylov vectors, model reduction of damped structural dynamics systems, and one-sided and two-sided unsymmetric block-Lanczos model-reduction algorithms.

  7. The entomopathogenic fungus Metarhizium anisopliae for mosquito control. Impact on the adult stage of the African malaria vector Anopheles gambiae and filariasis vector Culex quinquefasciatus

    Microsoft Academic Search

    E. J. Scholte

    2004-01-01

    Insect-pathogenie fungi for mosquito control (Chapters 1-3)Malaria and lymphatic tilariasis impose serious human health burdens in the tropics. Up to 500 million cases of malaria are reported annually, resulting in an estimated 1.5-2.7million deaths, of which 90% occur in sub-Saharan Africa. Malaria is caused by protozoa of the genus Plasmodium and is transmitted through bites of mosquitoes belonging to the

  8. Preliminary performance of a vertical-attitude takeoff and landing, supersonic cruise aircraft concept having thrust vectoring integrated into the flight control system

    NASA Technical Reports Server (NTRS)

    Robins, A. W.; Beissner, F. L., Jr.; Domack, C. S.; Swanson, E. E.

    1985-01-01

    A performance study was made of a vertical attitude takeoff and landing (VATOL), supersonic cruise aircraft concept having thrust vectoring integrated into the flight control system. Those characteristics considered were aerodynamics, weight, balance, and performance. Preliminary results indicate that high levels of supersonic aerodynamic performance can be achieved. Further, with the assumption of an advanced (1985 technology readiness) low bypass ratio turbofan engine and advanced structures, excellent mission performance capability is indicated.

  9. Instantaneous current vector control-based soft-switched high-frequency resonant inverter using static induction transistors for induction-heating power supply

    Microsoft Academic Search

    Hiroyuki Ogiwara; B. S. Nath; M. Nakaoka

    1995-01-01

    This paper describes a voltage-clamped resonant high-frequency inverter with quasi-resonant switches and load-dependent resonant tank, which can operate at a zero-current soft-switching mode over a wide load range as well as in the power regulation process. The operating principle of this inverter is presented and its instantaneous current vector controlled power regulation scheme is proposed. The steady-state operating characteristics of

  10. Long-lasting insecticide-treated house screens and targeted treatment of productive breeding-sites for dengue vector control in Acapulco, Mexico

    PubMed Central

    Che-Mendoza, Azael; Guillermo-May, Guillermo; Herrera-Bojórquez, Josué; Barrera-Pérez, Mario; Dzul-Manzanilla, Felipe; Gutierrez-Castro, Cipriano; Arredondo-Jiménez, Juan I.; Sánchez-Tejeda, Gustavo; Vazquez-Prokopec, Gonzalo; Ranson, Hilary; Lenhart, Audrey; Sommerfeld, Johannes; McCall, Philip J.; Kroeger, Axel; Manrique-Saide, Pablo

    2015-01-01

    Background Long-lasting insecticidal net screens (LLIS) fitted to domestic windows and doors in combination with targeted treatment (TT) of the most productive Aedes aegypti breeding sites were evaluated for their impact on dengue vector indices in a cluster-randomised trial in Mexico between 2011 and 2013. Methods Sequentially over 2 years, LLIS and TT were deployed in 10 treatment clusters (100 houses/cluster) and followed up over 24 months. Cross-sectional surveys quantified infestations of adult mosquitoes, immature stages at baseline (pre-intervention) and in four post-intervention samples at 6-monthly intervals. Identical surveys were carried out in 10 control clusters that received no treatment. Results LLIS clusters had significantly lower infestations compared to control clusters at 5 and 12 months after installation, as measured by adult (male and female) and pupal-based vector indices. After addition of TT to the intervention houses in intervention clusters, indices remained significantly lower in the treated clusters until 18 (immature and adult stage indices) and 24 months (adult indices only) post-intervention. Conclusions These safe, simple affordable vector control tools were well-accepted by study participants and are potentially suitable in many regions at risk from dengue worldwide. PMID:25604761

  11. Vector quantization

    Microsoft Academic Search

    Robert M. Gray

    1984-01-01

    A vector quantizer is a system for mapping a sequence of continuous or discrete vectors into a digital sequence suitable for communication over or storage in a digital channel. The goal of such a system is data compression: to reduce the bit rate so as to minimize communication channel capacity or digital storage memory requirements while maintaining the necessary fidelity

  12. Embracing the Open-Source Movement for the Management of Spatial Data: A Case Study of African Trypanosomiasis in Kenya

    PubMed Central

    Langley, Shaun A.; Messina, Joseph P.

    2011-01-01

    The past decade has seen an explosion in the availability of spatial data not only for researchers, but the public alike. As the quantity of data increases, the ability to effectively navigate and understand the data becomes more challenging. Here we detail a conceptual model for a spatially explicit database management system that addresses the issues raised with the growing data management problem. We demonstrate utility with a case study in disease ecology: to develop a multi-scale predictive model of African Trypanosomiasis in Kenya. International collaborations and varying technical expertise necessitate a modular open-source software solution. Finally, we address three recurring problems with data management: scalability, reliability, and security. PMID:21686072

  13. Three-dimensional tensor controlled-source electromagnetic modeling based on the vector finite-element method

    NASA Astrophysics Data System (ADS)

    Hu, Ying-Cai; Li, Tong-Lin; Fan, Cui-Song; Wang, Da-Yong; Li, Jian-Ping

    2015-03-01

    Scalar CSAMT is only suitable for measurements in one and two dimensions perpendicular to geological structures. For complex 3D geoelectric structure, tensor CSAMT is more suitable. In this paper, we discuss 3D tensor CSAMT forward modeling using the vector finite-element method. To verify the feasibility of the algorithm, we calculate the electric field, magnetic field, and tensor impedance of the 3D CSAMT far-zone field in layered media and compare them with theoretical solutions. In addition, a three-dimensional anomaly in half-space is also simulated, and the response characteristics of the impedance tensor and the apparent resistivity and impedance phase are analyzed. The results suggest that the vector finite-element method produces high-precision electromagnetic field and impedance tensor data, satisfies the electric field discontinuity, and does not require divergence correction using the vector finite-element method.

  14. VECTOR/PATHOGEN/HOST INTERACTION, TRANSMISSION Glossina Proteolytic Lectin Does Not Require a Carbohydrate Moiety

    E-print Network

    Hammock, Bruce D.

    trypanosomiasis, a debilitating disease affecting humans and other ver- tebrates. These ßies are found only in Africa south of the Sahara and have been associated with the trans- mission of African trypanosomiasis

  15. Vector Fields

    NSDL National Science Digital Library

    Dray, Tevian

    2006-01-01

    Vector fields are vectors which change from point to point. A standard example is the velocity of moving air, in other words, wind. For instance, the current wind pattern in the San Francisco area can be found at . This site has a 2-dimensional representation; careful reading of the webpage will tell you at what elevation the wind is shown. How would you represent a vector field in 3 dimensions? What features are important? Some simple examples are shown. Each can be rotated by clicking and dragging with the mouse. Explore!

  16. Cloning vector

    DOEpatents

    Guilfoyle, R.A.; Smith, L.M.

    1994-12-27

    A vector comprising a filamentous phage sequence containing a first copy of filamentous phage gene X and other sequences necessary for the phage to propagate is disclosed. The vector also contains a second copy of filamentous phage gene X downstream from a promoter capable of promoting transcription in a bacterial host. In a preferred form of the present invention, the filamentous phage is M13 and the vector additionally includes a restriction endonuclease site located in such a manner as to substantially inactivate the second gene X when a DNA sequence is inserted into the restriction site. 2 figures.

  17. Coastline Detection in Synthetic Aperture Radar (SAR) Images by Integrating Watershed Transformation and Controllable Gradient Vector Flow (GVF) Snake Model

    Microsoft Academic Search

    Guofeng Sheng; Wen Yang; Xinping Deng; Chu He; Yongfeng Cao; Hong Sun

    2012-01-01

    Detection of coastline in synthetic aperture radars (SARs) is difficult due to the presence of speckle effect and strong signal return from wind-roughened, wave-modulated sea. This paper presents a new approach to detect coastlines from SAR images by integrating watershed transformation and gradient vector flow (GVF) snake model. Several improvements have been made to improve the accuracy and efficiency of

  18. Vector quantization

    NASA Technical Reports Server (NTRS)

    Gray, Robert M.

    1989-01-01

    During the past ten years Vector Quantization (VQ) has developed from a theoretical possibility promised by Shannon's source coding theorems into a powerful and competitive technique for speech and image coding and compression at medium to low bit rates. In this survey, the basic ideas behind the design of vector quantizers are sketched and some comments made on the state-of-the-art and current research efforts.

  19. Elliptic-symmetry vector optical fields.

    PubMed

    Pan, Yue; Li, Yongnan; Li, Si-Min; Ren, Zhi-Cheng; Kong, Ling-Jun; Tu, Chenghou; Wang, Hui-Tian

    2014-08-11

    We present in principle and demonstrate experimentally a new kind of vector fields: elliptic-symmetry vector optical fields. This is a significant development in vector fields, as this breaks the cylindrical symmetry and enriches the family of vector fields. Due to the presence of an additional degrees of freedom, which is the interval between the foci in the elliptic coordinate system, the elliptic-symmetry vector fields are more flexible than the cylindrical vector fields for controlling the spatial structure of polarization and for engineering the focusing fields. The elliptic-symmetry vector fields can find many specific applications from optical trapping to optical machining and so on. PMID:25321015

  20. Evaluation of an indirect fluorescent antibody test, enzyme-linked immunosorbent assay and quantification of immunoglobulins in the diagnosis of bovine trypanosomiasis

    Microsoft Academic Search

    A. G. Luckins; D. Mehlitz

    1978-01-01

    An indirect fluorescent antibody test (IFAT), a microscale version of the enzyme-linked immunosorbent assay (microELISA) and determination of IgM levels in serum were assessed for their comparative diagnostic value in the detection of bovine trypanosomiasis. Serum samples from drug-treated N'dama cattle and untreated N'dama and Zebu cattle from Liberia were examined for the presence of antibodies to trypanosomes. In the

  1. Design and in vitro characterization of a single regulatory module for efficient control of gene expression in both plasmid DNA and a self-inactivating lentiviral vector.

    PubMed Central

    Ogueta, S. B.; Yao, F.; Marasco, W. A.

    2001-01-01

    BACKGROUND: Regulation of transgene expression in target cells represents a critical and challenging aspect of gene therapy. Recently, a two-plasmid tetracycline-inducible system was developed in which the tetracycline repressor (tetR) alone, rather than the tetR-VP16 fusion derivative, was shown to function as a potent trans-modulator of a second plasmid that contains two tandem repeats of the tetracycline operator (tetO) inserted between the TATA box and the transcription start site of the hCMV major immediate-early promoter. A technological advance in this area would be the development of a single autoregulatory cassette that incorporates both of these components into nonviral and viral gene transfer vectors. For the latter, an inducible lentiviral vector that is capable of temporal and quantitative control of gene expression in either dividing or nondividing cells is highly desirable. MATERIALS AND METHODS: A one-piece inducible (1Pi) autoregulatory cassette was constructed to provide IRES-mediated translation of the tetR as well as tight control over the tetO unit preventing transcription initiation of the first cistron in the absence of the tetracycline. To increase efficiency of tetR-mediated repression, a nuclear localization signal was incorporated at the 3' end of the tetR gene. Regulation of gene expression at the transcriptional and protein level was analyzed in transient transfection experiments using plasmid DNA. Construction of a self-inactivating lentiviral vector containing this 1Pi cassette allowed the study of its long-term effectiveness in primary human cells. RESULTS: The 1Pi autoregulatory cassette when incorporated into plasmid DNA allows efficient control of the secretable hEGF as well as eGFP expression in a variety of cell types. Transient transfection studies demonstrated that the time course of repression is different for the 1Pi and two-plasmid system (2Pi). In the 2Pi system, greater repression is seen with the first 24-48 hr; however, by 72 hr, similar levels of repression with the 1Pi and 2Pi systems are obtained. This regulation is reached three times faster when the tetR is modified with a nuclear localization signal to direct nascent proteins into the nuclear compartment. In addition, stable transduction of human umbilical vein endothelial cells (HUVEC) with a self-inactivating lentiviral vector incorporating this single regulator cassette provided tetracycline-inducible control of gene expression that is not diminished over time and is completely reversible upon removal of tetracycline. CONCLUSIONS: These results suggest a model in which the 1Pi autoregulatory system reaches a steady state over time, the minimal amount of tetR produced by the basal activity of the CMV promoter and accumulated is adequate to replace the tetR that is lost over time. These studies also show that the inducible self-inactivating lentiviral vector can temporally and reversibly regulate transgene expression in HUVECs. The use of this transcriptional control unit in both nonviral and viral vector delivery systems will constitute an attractive technological advance for many gene therapy applications where temporal and quantitative control of gene expression is desired. The strengths and limitations of the 1Pi system are discussed. PMID:11591893

  2. Evaluation of Metarhizium anisopliae for the control of Culicoides brevitarsis Kieffer (Diptera: Ceratopogonidae), the principal vector of bluetongue virus in Australia.

    PubMed

    Nicholas, A H; McCorkell, B

    2014-06-01

    Four isolates of the entomopathogenic fungus Metarhizium anisopliae were tested for their potential to control the biting midge Culicoides brevitarsis, the principal vector of bluetongue virus in Australia. Adult C. brevitarsis died three to eight days after walking on paper substrate treated with 0.7 g/m(2) conidia of any of the isolates, indicating that M. anisopliae has potential as a surface treatment or topical application control strategy. Incorporation of the fungus into freshly excreted cattle dung at rates of between 0.25 and 1 g conidia/kg reduced the emergence of adult midges by up to 98.5% compared to untreated dung indicating that M. anisopliae has the potential to control C. brevitarsis larvae in cattle dung. Three of the isolates produced similar mortality rates on adult and immature C. brevitarsis while the fourth isolate produced lower, but still significant, mortality rates on adult and immature stages. PMID:24820575

  3. Common-Mode Circulating Current Control of Paralleled Interleaved Three-Phase Two-Level Voltage-Source Converters With Discontinuous Space-Vector Modulation

    SciTech Connect

    Zhang, Di [ORNL; Wang, Fei [ORNL; Burgos, Rolando [ABB; Boroyevich, Dushan [Virginia Polytechnic Institute and State University (Virginia Tech)

    2011-01-01

    This paper presents a control method to limit the common-mode (CM) circulating current between paralleled three-phase two-level voltage-source converters (VSCs) with discontinuous space-vector pulsewidth modulation (DPWM) and interleaved switching cycles. This CM circulating current can be separated into two separate components based on their frequency; the high-frequency component, close to the switching frequency, can be effectively limited by means of passive components; the low-frequency component, close to the fundamental frequency, embodies the jumping CM circulating current observed in parallel VSCs. This is the main reason why it is usually recommended not to implement discontinuous and interleaving PWM together. The origin of this low-frequency circulating current is analyzed in detail, and based on this, a method to eliminate its presence is proposed by impeding the simultaneous use of different zero vectors between the converters. This control method only requires six additional switching actions per line cycle, presenting a minimum impact on the converter thermal design. The analysis and the feasibility of the control method are verified by simulation and experimental results.

  4. Navigational Vectors

    NSDL National Science Digital Library

    2008-12-10

    This is a high school instructional unit that features nine lessons relating to vectors. Students build understanding of vector properties as they learn airplane navigation. Problem-based learning activities include reading real-time weather maps, tracking airplanes flying in U.S. skies, calculating vector components, analyzing effects of wind velocity, and completing training segments similar to a private pilot certification program. Participants have access to help from experts at the Polaris Career Center. Comprehensive teacher guides, student guides, reference materials, and assessments are included. This resource was developed by the Center for Innovation in Science and Engineering Education (CIESE). Participation is cost-free; additional options are available for registered users.

  5. The Prevention and Control of HIV/AIDS, TB and Vector-borne Diseases in Informal Settlements: Challenges, Opportunities and Insights

    PubMed Central

    Mercado, Susan P.; Becker, Daniel; Edmundo, Katia; Mugisha, Frederick

    2007-01-01

    Today’s urban settings are redefining the field of public health. The complex dynamics of cities, with their concentration of the poorest and most vulnerable (even within the developed world) pose an urgent challenge to the health community. While retaining fidelity to the core principles of disease prevention and control, major adjustments are needed in the systems and approaches to effectively reach those with the greatest health risks (and the least resilience) within today’s urban environment. This is particularly relevant to infectious disease prevention and control. Controlling and preventing HIV/AIDS, tuberculosis and vector-borne diseases like malaria are among the key global health priorities, particularly in poor urban settings. The challenge in slums and informal settlements is not in identifying which interventions work, but rather in ensuring that informal settlers: (1) are captured in health statistics that define disease epidemiology and (2) are provided opportunities equal to the rest of the population to access proven interventions. Growing international attention to the plight of slum dwellers and informal settlers, embodied by Goal 7 Target 11 of the Millennium Development Goals, and the considerable resources being mobilized by the Global Fund to fight AIDS, TB and malaria, among others, provide an unprecedented potential opportunity for countries to seriously address the structural and intermediate determinants of poor health in these settings. Viewed within the framework of the “social determinants of disease” model, preventing and controlling HIV/AIDS, TB and vector-borne diseases requires broad and integrated interventions that address the underlying causes of inequity that result in poorer health and worse health outcomes for the urban poor. We examine insights into effective approaches to disease control and prevention within poor urban settings under a comprehensive social development agenda. PMID:17431796

  6. Pipeline vectorization

    Microsoft Academic Search

    Markus Weinhardt; Wayne Luk

    2001-01-01

    This paper presents pipeline vectorization, amethod for synthesizing hardware pipelines based on softwarevectorizing compilers. The method improves eciencyand ease of development of hardware designs, particularlyfor users with little electronics design experience. We proposeseveral loop transformations to customize pipelinesto meet hardware resource constraints, while maximizingavailable parallelism. For run-time recongurable systems,we apply hardware specialization to increase...

  7. System simulation of 3-phase PWM rectifier based on novel voltage space vector

    Microsoft Academic Search

    Kexin Wei; Gang Zhang; Shuiming Wang

    2008-01-01

    A novel voltage space vector control method based on hysteresis current control is proposed. This method gives the optimal space vector by detecting the current error space vector and the system reference voltage space vector, and then controls the current error below the hysteresis width. Voltage space vector is introduced into the control system to eliminate the phase interference, and

  8. Convergence rates for iterative vector space projection methods for control of two deformable mirrors for compensation of both amplitude and phase fluctuations.

    PubMed

    Barchers, Jeffrey D

    2002-04-20

    The control of two deformable mirrors for compensation of time-varying fluctuations in the complex field that results from wave propagation through a turbulent medium is considered. Iterative vector space projection methods are utilized to determine the control commands to be applied to the two deformable mirrors. Convergence of the iterative algorithm is accelerated when the algorithm is initialized, at each measurement period, with the values for the phase commands obtained from the previous measurement period. Furthermore, it is found that, if the sample frequency is sufficiently greater than the Greenwood frequency, then only a single iterative step at each measurement period is required to obtain good compensation of both amplitude and phase fluctuations. PMID:12003212

  9. APPENDIX D. VECTOR ANALYSIS 1 Vector Analysis

    E-print Network

    Callen, James D.

    APPENDIX D. VECTOR ANALYSIS 1 Appendix D Vector Analysis The following conventions are used in this appendix and throughout the book: f, g, , are scalar functions of x, t; A, B, C, D are vector functions of x, t; A = |A| A · A is the magnitude or length of the vector A; ^eA A/A is a unit vector

  10. Toxicity effect of Delonix elata (Yellow Gulmohr) and predatory efficiency of Copepod, Mesocyclops aspericornis for the control of dengue vector, Aedes aegypti

    PubMed Central

    Vasugi, Chellamuthu; Kamalakannan, Siva; Murugan, Kadarkarai

    2013-01-01

    Objective To evaluate the toxicity, predatory efficiency of Delonix elata (D. elata) and Mesocyclops aspericornis (M. aspericornis) against dengue vector, Aedes aegypti (Ae. aegypti). Methods A mosquitocidal bioassay was conducted at different concentration of plant extract followed by WHO standard method. The probit analysis of each tested concentration and control were observed by using software SPSS 11 version package. The each tested concentration variable was assessed by DMRT method. The predatory efficiency of copepod was followed by Deo et al., 1988. The predator, M. aspericornis was observed for mortality, abnormalities, survival and swimming activity after 24 h treatment of plant and also predation on the mosquito larvae were observed. Results D. elata were tested for biological activity against the larvae, and pupae of Ae. aegypti. Significant mortality effects were observed in each life stage. The percentage of mortality was 100% in first and second instars whereas 96%, 92% in third and fourth instars. Fitted probit-mortality curves for larvae indicated the median and 90% lethal concentrations of D. elata for instars 1-4 to be 4.91 (8.13), 5.16 (8.44), 5.95 (7.76) and 6.87 (11.23), respectively. The results indicate that leaf extract exhibits significant biological activity against life stages. The present study revealed that D. elata is potentially important in the control of Ae. aegypti. Similar studies were conducted for predatory efficiency of Copepod, M. aspericornis against mosquito vector Ae. Aegypti. This study reported that the predatory copepod fed on 39% and 25% in I and III instar larvae of mosquito and in combined treatment of D. elata and copepod maximum control of mosquito larval states and at 83%, 80%, 75% and 53% in I, II, III and IV instars, respectively. Conclusions The combined action of plant extract and predatory copepod to effectively control mosquito population and reduce the dengue transmitting diseases.

  11. Environments and trypanosomiasis risks for early herders in the later Holocene of the Lake Victoria basin, Kenya.

    PubMed

    Chritz, Kendra L; Marshall, Fiona B; Zagal, M Esperanza; Kirera, Francis; Cerling, Thure E

    2015-03-24

    Specialized pastoralism developed ?3 kya among Pastoral Neolithic Elmenteitan herders in eastern Africa. During this time, a mosaic of hunters and herders using diverse economic strategies flourished in southern Kenya. It has been argued that the risk for trypanosomiasis (sleeping sickness), carried by tsetse flies in bushy environments, had a significant influence on pastoral diversification and migration out of eastern Africa toward southern Africa ?2 kya. Elmenteitan levels at Gogo Falls (ca. 1.9-1.6 kya) preserve a unique faunal record, including wild mammalian herbivores, domestic cattle and caprines, fish, and birds. It has been suggested that a bushy/woodland habitat that harbored tsetse fly constrained production of domestic herds and resulted in subsistence diversification. Stable isotope analysis of herbivore tooth enamel (n = 86) from this site reveals, instead, extensive C4 grazing by both domesticates and the majority of wild herbivores. Integrated with other ecological proxies (pollen and leaf wax biomarkers), these data imply an abundance of C4 grasses in the Lake Victoria basin at this time, and thus little risk for tsetse-related barriers to specialized pastoralism. These data provide empirical evidence for the existence of a grassy corridor through which small groups of herders could have passed to reach southern Africa. PMID:25775535

  12. Hemoculture and Polymerase Chain Reaction Using Primers TCZ1/TCZ2 for the Diagnosis of Canine and Feline Trypanosomiasis.

    PubMed

    Eloy, Luciano José; Lucheis, Simone Baldini

    2012-01-01

    Introduction. American trypanosomiasis, also known as Chagas disease, is a zoonosis caused by Trypanosoma cruzi (T. cruzi). Dogs and cats participate actively in this parasite's transmission cycle. This study aimed at evaluating the occurrence of T. cruzi in dogs and cats from Botucatu, SP, Brazil, as well as at evaluating the technique of hemoculture in LIT (liver infusion tryptose) medium by polymerase chain reaction (PCR). Methods. Blood samples were collected from 50 dogs and 50 cats in Botucatu-SP, Brazil. For hemoculture, the samples were inoculated in LIT medium, and readings were performed for four months. Upon completion of such period, all the hemocultures were processed for parasitic DNA extraction. The PCR reactions were performed by using primers TCZ1/TCZ2. Results. Ten dogs and ten cats (20%) were positive to PCR, and four dogs and three cats (7%) were positive to hemoculture. Only in a one cat sample (1%) there was confirmation of positive hemoculture by PCR for T. cruzi. Conclusions. Results showed that PCR was a suitable tool for the confirmation of the parasite detection in hemoculture samples, and that dogs and cats from Botucatu, SP, Brazil, are maintaining the role of household reservoirs of T. cruzi, which reinforces the need for constant epidemiologic surveillance for this zoonosis. PMID:23738124

  13. Noise generated by a flight weight, air flow control valve in a vertical takeoff and landing aircraft thrust vectoring system

    NASA Astrophysics Data System (ADS)

    Huff, Ronald G.

    1989-02-01

    Tests were conducted in the NASA Lewis Research Center's Powered Lift Facility to experimentally evaluate the noise generated by a flight weight, 12 in. butterfly valve installed in a proposed vertical takeoff and landing thrust vectoring system. Fluctuating pressure measurements were made in the circular duct upstream and downstream of the valve. This data report presents the results of these tests. The maximum overall sound pressure level is generated in the duct downstream of the valve and reached a value of 180 dB at a valve pressure ratio of 2.8. At the higher valve pressure ratios the spectra downstream of the valve is broad banded with its maximum at 1000 Hz.

  14. Noise generated by a flight weight, air flow control valve in a vertical takeoff and landing aircraft thrust vectoring system

    NASA Technical Reports Server (NTRS)

    Huff, Ronald G.

    1989-01-01

    Tests were conducted in the NASA Lewis Research Center's Powered Lift Facility to experimentally evaluate the noise generated by a flight weight, 12 in. butterfly valve installed in a proposed vertical takeoff and landing thrust vectoring system. Fluctuating pressure measurements were made in the circular duct upstream and downstream of the valve. This data report presents the results of these tests. The maximum overall sound pressure level is generated in the duct downstream of the valve and reached a value of 180 dB at a valve pressure ratio of 2.8. At the higher valve pressure ratios the spectra downstream of the valve is broad banded with its maximum at 1000 Hz.

  15. Field trial on a novel control method for the dengue vector, Aedes aegypti by the systematic use of Olyset® Net and pyriproxyfen in Southern Vietnam

    PubMed Central

    2013-01-01

    Background Jars, tanks, and drums provide favorable rearing/breeding sites for Aedes aegypti in Vietnam. However, the use of insecticides to control mosquitoes at such breeding sites has not been approved in Vietnam since they are also often sources of drinking water, making larval vector control difficult. Mosquito nets pre-treated with long-lasting insecticide treated nets (LLITNs) form an effective measure for malaria control. We examined changes in the abundance of immature Aedes aegypti to evaluate the efficacy of covering ceramic jars with lids comprising one type of LLITN, Olyset® Net, in inhibiting oviposition by adult females, and to evaluate the effect of treating other breeding containers, such as flower vases, inside and around the outside of houses with a slow-release pyriproxyfen formulation to kill pupae. Methods We selected 313 households for the trial and 363 households for the control in Tan Chanh, Long An province, Vietnam. In the trial area, Olyset® Net lids were used to cover five major types of water container (ceramic jars, cylindrical concrete tanks, other concrete tanks, plastic drums, and plastic buckets), while pyriproxyfen was used to treat flower vases and ant traps. We also monitored dengue virus transmission by measuring anti-dengue IgM and IgG levels in healthy residents in both control and trial areas to estimate the effectiveness of Olyset® Net at controlling the dengue vector, Aedes aegypti. Results The container-index and house-index for immature Ae. aegypti fell steeply one month after treatment in the trial area. Lids with Olyset® Net that fit container openings clearly seemed to reduce the presence of immature Ae. aegypti as the density of pupae decreased 1 month after treatment in the trial area. Pyriproxyfen was also effective at killing pupae in the water containers in the trial area. Although the dengue seroconversion rate was not influenced by Olyset® Net, it was lower in two-five year old children when compared to older children and adults in both control and trial areas. Conclusions Our study showed that the treatment by Olyset® Net and pyriproxyfen had a strong negative effect on the prevalence of immature Ae. aegypti, which persisted for at least 5 months after treatment. PMID:23312018

  16. The Repellent DEET Potentiates Carbamate Effects via Insect Muscarinic Receptor Interactions: An Alternative Strategy to Control Insect Vector-Borne Diseases

    PubMed Central

    Abd-Ella, Aly; Stankiewicz, Maria; Mikulska, Karolina; Nowak, Wieslaw; Pennetier, Cédric; Goulu, Mathilde; Fruchart-Gaillard, Carole; Licznar, Patricia; Apaire-Marchais, Véronique; List, Olivier; Corbel, Vincent; Servent, Denis; Lapied, Bruno

    2015-01-01

    Insect vector-borne diseases remain one of the principal causes of human mortality. In addition to conventional measures of insect control, repellents continue to be the mainstay for personal protection. Because of the increasing pyrethroid-resistant mosquito populations, alternative strategies to reconstitute pyrethroid repellency and knock-down effects have been proposed by mixing the repellent DEET (N,N-Diethyl-3-methylbenzamide) with non-pyrethroid insecticide to better control resistant insect vector-borne diseases. By using electrophysiological, biochemichal, in vivo toxicological techniques together with calcium imaging, binding studies and in silico docking, we have shown that DEET, at low concentrations, interacts with high affinity with insect M1/M3 mAChR allosteric site potentiating agonist effects on mAChRs coupled to phospholipase C second messenger pathway. This increases the anticholinesterase activity of the carbamate propoxur through calcium-dependent regulation of acetylcholinesterase. At high concentrations, DEET interacts with low affinity on distinct M1/M3 mAChR site, counteracting the potentiation. Similar dose-dependent dual effects of DEET have also been observed at synaptic mAChR level. Additionally, binding and in silico docking studies performed on human M1 and M3 mAChR subtypes indicate that DEET only displays a low affinity antagonist profile on these M1/M3 mAChRs. These results reveal a selective high affinity positive allosteric site for DEET in insect mAChRs. Finally, bioassays conducted on Aedes aegypti confirm the synergistic interaction between DEET and propoxur observed in vitro, resulting in a higher mortality of mosquitoes. Our findings reveal an unusual allosterically potentiating action of the repellent DEET, which involves a selective site in insect. These results open exciting research areas in public health particularly in the control of the pyrethroid-resistant insect-vector borne diseases. Mixing low doses of DEET and a non-pyrethroid insecticide will lead to improvement in the efficiency treatments thus reducing both the concentration of active ingredients and side effects for non-target organisms. The discovery of this insect specific site may pave the way for the development of new strategies essential in the management of chemical use against resistant mosquitoes. PMID:25961834

  17. Microsatellite and mitochondrial markers reveal strong gene flow barriers for Anopheles farauti in the Solomon Archipelago: implications for malaria vector control.

    PubMed

    Ambrose, Luke; Cooper, Robert D; Russell, Tanya L; Burkot, Thomas R; Lobo, Neil F; Collins, Frank H; Hii, Jeffrey; Beebe, Nigel W

    2014-03-01

    Anopheles farauti is the primary malaria vector throughout the coastal regions of the Southwest Pacific. A shift in peak biting time from late to early in the night occurred following widespread indoor residue spraying of dichlorodiphenyltrichloro-ethane (DDT) and has persisted in some island populations despite the intervention ending decades ago. We used mitochondrial cytochrome oxidase I (COI) sequence data and 12 newly developed microsatellite markers to assess the population genetic structure of this malaria vector in the Solomon Archipelago. With geographically distinct differences in peak A. farauti night biting time observed in the Solomon Archipelago, we tested the hypothesis that strong barriers to gene flow exist in this region. Significant and often large fixation index (FST) values were found between different island populations for the mitochondrial and nuclear markers, suggesting highly restricted gene flow between islands. Some discordance in the location and strength of genetic breaks was observed between the mitochondrial and microsatellite markers. Since early night biting A. farauti individuals occur naturally in all populations, the strong gene flow barriers that we have identified in the Solomon Archipelago lend weight to the hypothesis that the shifts in peak biting time from late to early night have appeared independently in these disconnected island populations. For this reason, we suggest that insecticide impregnated bed nets and indoor residue spraying are unlikely to be effective as control tools against A. farauti occurring elsewhere, and if used, will probably result in peak biting time behavioural shifts similar to that observed in the Solomon Islands. PMID:24440418

  18. Intratumoral gene therapy versus intravenous gene therapy for distant metastasis control with 2-diethylaminoethyl-dextran methyl methacrylate copolymer non-viral vector-p53.

    PubMed

    Baliaka, A; Zarogoulidis, P; Domvri, K; Hohenforst-Schmidt, W; Sakkas, A; Huang, H; Le Pivert, P; Koliakos, G; Koliakou, E; Kouzi-Koliakos, K; Tsakiridis, K; Chioti, A; Siotou, E; Cheva, A; Zarogoulidis, K; Sakkas, L

    2014-02-01

    Lung cancer still remains to be challenged by novel treatment modalities. Novel locally targeted routes of administration are a methodology to enhance treatment and reduce side effects. Intratumoral gene therapy is a method for local treatment and could be used either in early-stage lung cancer before surgery or at advanced stages as palliative care. Novel non-viral vectors are also in demand for efficient gene transfection to target local cancer tissue and at the same time protect the normal tissue. In the current study, C57BL/6 mice were divided into three groups: (a) control, (b) intravenous and (c) intatumoral gene therapy. The novel 2-Diethylaminoethyl-Dextran Methyl Methacrylate Copolymer Non-Viral Vector (Ryujyu Science Corporation) was conjugated with plasmid pSicop53 from the company Addgene for the first time. The aim of the study was to evaluate the safety and efficacy of targeted gene therapy in a Lewis lung cancer model. Indeed, although the pharmacokinetics of the different administration modalities differs, the intratumoral administration presented increased survival and decreased distant metastasis. Intratumoral gene therapy could be considered as an efficient local therapy for lung cancer. PMID:24285215

  19. Microsatellite and mitochondrial markers reveal strong gene flow barriers for Anopheles farauti in the Solomon Archipelago: implications for malaria vector control?

    PubMed Central

    Ambrose, Luke; Cooper, Robert D.; Russell, Tanya L.; Burkot, Thomas R.; Lobo, Neil F.; Collins, Frank H.; Hii, Jeffrey; Beebe, Nigel W.

    2014-01-01

    Anopheles farauti is the primary malaria vector throughout the coastal regions of the Southwest Pacific. A shift in peak biting time from late to early in the night occurred following widespread indoor residue spraying of dichlorodiphenyltrichloroethane (DDT) and has persisted in some island populations despite the intervention ending decades ago. We used mitochondrial cytochrome oxidase I (COI) sequence data and 12 newly developed microsatellite markers to assess the population genetic structure of this malaria vector in the Solomon Archipelago. With geographically distinct differences in peak A. farauti night biting time observed in the Solomon Archipelago, we tested the hypothesis that strong barriers to gene flow exist in this region. Significant and often large fixation index (FST) values were found between different island populations for the mitochondrial and nuclear markers, suggesting highly restricted gene flow between islands. Some discordance in the location and strength of genetic breaks was observed between the mitochondrial and microsatellite markers. Since early night biting A. farauti individuals occur naturally in all populations, the strong gene flow barriers that we have identified in the Solomon Archipelago lend weight to the hypothesis that the shifts in peak biting time from late to early night have appeared independently in these disconnected island populations. For this reason, we suggest that insecticide impregnated bed nets and indoor residue spraying are unlikely to be effective as control tools against A. farauti occurring elsewhere, and if used, will probably result in peak biting time behavioural shifts similar to that observed in the Solomon Islands. PMID:24440418

  20. Revealed Preference of the Federal Reserve: Using Inverse-Control Theory to Interpret the Policy Equation of a Vector Autoregression

    Microsoft Academic Search

    Michael K. Salemi

    1995-01-01

    How close is observed Federal Reserve policy to policy that would be optimal in the control-theory sense? The question is addressed by using an inverse-control methodology. Federal Reserve policy is characterized by a feedback equation for either changes in the interest rate or money stock. Optimal policy is characterized by solution of the Ricatti equation. Parameters are estimated that characterize

  1. The Use of Mini-Vector Instructions for Implementing High-Speed Feedback Controllers on General-Purpose

    E-print Network

    Skadron, Kevin

    -speed, energy-storage flywheel, and the purpose of the testbed is to provide a platform in which new control for AMBs in high-speed environments like the flywheel, where greater speeds provide greater energy-storage-spin- rate flywheel. This application is representative of many control environments that require both high

  2. Spatial and temporal distribution of the malaria mosquito Anopheles arabiensis in northern Sudan: influence of environmental factors and implications for vector control

    PubMed Central

    Ageep, Tellal B; Cox, Jonathan; Hassan, M'oawia M; Knols, Bart GJ; Benedict, Mark Q; Malcolm, Colin A; Babiker, Ahmed; El Sayed, Badria B

    2009-01-01

    Background Malaria is an important public health problem in northern Sudan, but little is known about the dynamics of its transmission. Given the characteristic low densities of Anopheles arabiensis and the difficult terrain in this area, future vector control strategies are likely to be based on area-wide integrated pest management (AW-IPM) that may include the sterile insect technique (SIT). To support the planning and implementation of future AW-IPM activities, larval surveys were carried out to provide key data on spatial and seasonal dynamics of local vector populations. Methods Monthly cross-sectional larval surveys were carried out between March 2005 and May 2007 in two localities (Dongola and Merowe) adjacent to the river Nile. A stratified random sampling strategy based on the use of Remote Sensing (RS), Geographical Information Systems (GIS) and the Global Positioning System (GPS) was used to select survey locations. Breeding sites were mapped using GPS and data on larval density and breeding site characteristics were recorded using handheld computers. Bivariate and multivariate logistic regression models were used to identify breeding site characteristics associated with increased risk of presence of larvae. Seasonal patterns in the proportion of breeding sites positive for larvae were compared visually to contemporaneous data on climate and river height. Results Of a total of 3,349 aquatic habitats sampled, 321 (9.6%) contained An. arabiensis larvae. The frequency with which larvae were found varied markedly by habitat type. Although most positive sites were associated with temporary standing water around the margins of the main Nile channel, larvae were also found at brickworks and in areas of leaking pipes and canals – often far from the river. Close to the Nile channel, a distinct seasonal pattern in larval populations was evident and appeared to be linked to the rise and fall of the river level. These patterns were not evident in vector populations breeding in artificial water sources away from the river. Conclusion The GIS-based survey strategy developed in this study provides key data on the population dynamics of An. arabiensis in Northern State. Quantitative estimates of the contributions of various habitat types and their proximity to settlements provide a basis for planning a strategy for reducing malaria risk by elimination of the vector population. PMID:19500425

  3. ARE THERE PATHOGENS IN YOUR SEWAGE SLUDGE? CHANGING APPROAHCES TO CONTROLLING PATHOGENS IN SEWAGE SLUDGE AND THEIR VECTOR ATTRACTIVENESS.

    EPA Science Inventory

    This presentation will review the commonly employed Class A & B processes for controlling pathogens; note how extensively they are used; and discuss issues and concerns. Processes presently being researched will also be noted together with EPA's methodology for determining equiva...

  4. Linking Oviposition Site Choice to Offspring Fitness in Aedes aegypti: Consequences for Targeted Larval Control of Dengue Vectors

    Microsoft Academic Search

    Jacklyn Wong; Amy C. Morrison; Steven T. Stoddard; Helvio Astete; Yui Yin Chu; Imaan Baseer; Thomas W. Scott

    2012-01-01

    BackgroundCurrent Aedes aegypti larval control methods are often insufficient for preventing dengue epidemics. To improve control efficiency and cost-effectiveness, some advocate eliminating or treating only highly productive containers. The population-level outcome of this strategy, however, will depend on details of Ae. aegypti oviposition behavior.Methodology\\/Principal FindingsWe simultaneously monitored female oviposition and juvenile development in 80 experimental containers located across 20 houses

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

    Microsoft Academic Search

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

    2004-01-01

    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.

  6. IFN-?-Dependent Nitric Oxide Production Is Not Linked to Resistance in Experimental African Trypanosomiasis

    Microsoft Academic Search

    Cheryl J. Hertz; John M. Mansfield

    1999-01-01

    Resistance to African trypanosomes is dependent on B cell and Th1 cell responses to the variant surface glycoprotein (VSG). While B cell responses to VSG control levels of parasitemia, the cytokine responses of Th1 cells to VSG appear to be linked to the control of parasites in extravascular tissues. We have recently shown that IFN-? knockout (IFN-? KO) mice are

  7. New Chemical Scaffolds for Human African Trypanosomiasis Lead Discovery from a Screen of Tyrosine Kinase Inhibitor Drugs

    PubMed Central

    Behera, Ranjan; Thomas, Sarah M.

    2014-01-01

    Human African trypanosomiasis (HAT) is caused by the protozoan Trypanosoma brucei. New drugs are needed to treat HAT because of undesirable side effects and difficulties in the administration of the antiquated drugs that are currently used. In human proliferative diseases, protein tyrosine kinase (PTK) inhibitors (PTKIs) have been developed into drugs (e.g., lapatinib and erlotinib) by optimization of a 4-anilinoquinazoline scaffold. Two sets of facts raise a possibility that drugs targeted against human PTKs could be “hits” for antitrypanosomal lead discoveries. First, trypanosome protein kinases bind some drugs, namely, lapatinib, CI-1033, and AEE788. Second, the pan-PTK inhibitor tyrphostin A47 blocks the endocytosis of transferrin and inhibits trypanosome replication. Following up on these concepts, we performed a focused screen of various PTKI drugs as possible antitrypanosomal hits. Lapatinib, CI-1033, erlotinib, axitinib, sunitinib, PKI-166, and AEE788 inhibited the replication of bloodstream T. brucei, with a 50% growth inhibitory concentration (GI50) between 1.3 ?M and 2.5 ?M. Imatinib had no effect (i.e., GI50 > 10 ?M). To discover leads among the drugs, a mouse model of HAT was used in a proof-of-concept study. Orally administered lapatinib reduced parasitemia, extended the survival of all treated mice, and cured the trypanosomal infection in 25% of the mice. CI-1033 and AEE788 reduced parasitemia and extended the survival of the infected mice. On the strength of these data and noting their oral bioavailabilities, we propose that the 4-anilinoquinazoline and pyrrolopyrimidine scaffolds of lapatinib, CI-1033, and AEE788 are worth optimizing against T. brucei in medicinal chemistry campaigns (i.e., scaffold repurposing) to discover new drugs against HAT. PMID:24468788

  8. Trypanosoma brucei rhodesiense Transmitted by a Single Tsetse Fly Bite in Vervet Monkeys as a Model of Human African Trypanosomiasis

    PubMed Central

    Thuita, John K.; Kagira, John M.; Mwangangi, David; Matovu, Enock; Turner, C. M. R.; Masiga, Daniel

    2008-01-01

    We have investigated the pathogenicity of tsetse (Glossina pallidipes)-transmitted cloned strains of Trypanosoma brucei rhodesiense in vervet monkeys. Tsetse flies were confirmed to have mature trypanosome infections by xenodiagnosis, after which nine monkeys were infected via the bite of a single infected fly. Chancres developed in five of the nine (55.6%) monkeys within 4 to 8 days post infection (dpi). All nine individuals were successfully infected, with a median pre-patent period of 4 (range?=?4–10) days, indicating that trypanosomes migrated from the site of fly bite to the systemic circulation rapidly and independently of the development of the chancre. The time lag to detection of parasites in cerebrospinal fluid (CSF) was a median 16 (range?=?8–40) days, marking the onset of central nervous system (CNS, late) stage disease. Subsequently, CSF white cell numbers increased above the pre-infection median count of 2 (range?=?0–9) cells/µl, with a positive linear association between their numbers and that of CSF trypanosomes. Haematological changes showed that the monkeys experienced an early microcytic-hypochromic anaemia and severe progressive thrombocytopaenia. Despite a 3-fold increase in granulocyte numbers by 4 dpi, leucopaenia occurred early (8 dpi) in the monkey infection, determined mainly by reductions in lymphocyte numbers. Terminally, leucocytosis was observed in three of nine (33%) individuals. The duration of infection was a median of 68 (range?=?22–120) days. Strain and individual differences were observed in the severity of the clinical and clinical pathology findings, with two strains (KETRI 3741 and 3801) producing a more acute disease than the other two (KETRI 3804 and 3928). The study shows that the fly-transmitted model accurately mimics the human disease and is therefore a suitable gateway to understanding human African trypanosomiasis (HAT; sleeping sickness). PMID:18846231

  9. Power balancing in variable speed wind-energy systems using vector control of front-end converters

    Microsoft Academic Search

    Roberto Cárdenas; Rubén Peña; Marcelo Pérez; Fernando Vargas; Greg Asher; Jon Clare

    2005-01-01

    This paper presents a novel power balance control method for wind energy systems feeding an isolated grid. The system is based on a variable-speed wind energy conversion system (WECS) connected to an AC load using a power converter. An energy storage system, connected to the AC load using an additional converter, is used to balance the power generated by the

  10. might, however, be a cheap and effective alternative to conventional pesticides for vector control, and one that

    E-print Network

    deYoung, Brad

    ­1642 3 MacDonald, G. (1957) The Epidemiology and Control of Malaria, Oxford University Press 4 Hargreaves, K. et al. (2003) Anopheles arabiensis and An. quadriannu- latus resistance to DDT in South Africa from West Africa and further evidence for reproductive isolation of the Mopti form. Parassitologia 41

  11. Fast Fourier and discrete wavelet transforms applied to sensorless vector control induction motor for rotor bar faults diagnosis.

    PubMed

    Talhaoui, Hicham; Menacer, Arezki; Kessal, Abdelhalim; Kechida, Ridha

    2014-09-01

    This paper presents new techniques to evaluate faults in case of broken rotor bars of induction motors. Procedures are applied with closed-loop control. Electrical and mechanical variables are treated using fast Fourier transform (FFT), and discrete wavelet transform (DWT) at start-up and steady state. The wavelet transform has proven to be an excellent mathematical tool for the detection of the faults particularly broken rotor bars type. As a performance, DWT can provide a local representation of the non-stationary current signals for the healthy machine and with fault. For sensorless control, a Luenberger observer is applied; the estimation rotor speed is analyzed; the effect of the faults in the speed pulsation is compensated; a quadratic current appears and used for fault detection. PMID:25004798

  12. A vector controlled MCT matrix converter induction motor drive with minimized commutation times and enhanced waveform quality

    Microsoft Academic Search

    P. W. Wheeler; J. C. Clare; L. Empringham

    2002-01-01

    This paper describes the design, construction and testing of a 10 kVA three-phase to three-phase matrix converter induction motor drive. The converter has been built using discrete 65 Amp MOS controlled thyristors (MCTs). The commutation time has been minimized to avoid any unnecessary waveform distortion, particularly at low demanded output voltages. This minimization gives the Matrix Converter superior waveform quality

  13. Amazonian malaria: Asymptomatic human reservoirs, diagnostic challenges, environmentally-driven changes in mosquito vector populations, and the mandate for sustainable control strategies

    PubMed Central

    da Silva-Nunes, Mônica; Moreno, Marta; Conn, Jan E.; Gamboa, Dionicia; Abeles, Shira; Vinetz, Joseph M.; Ferreira, Marcelo U.

    2012-01-01

    Across the Americas and the Caribbean, nearly 561,000 slide-confirmed malaria infections were reported officially in 2008. The nine Amazonian countries accounted for 89% of these infections; Brazil and Peru alone contributed 56% and 7% of them, respectively. Local populations of the relatively neglected parasite P. vivax, which currently accounts for 77% of the regional malaria burden, are extremely diverse genetically and geographically structured. At a time when malaria elimination is placed on the public health agenda of several endemic countries, it remains unclear why malaria proved so difficult to control in areas of relatively low levels of transmission such as the Amazon Basin. We hypothesize that asymptomatic parasite carriage and massive environmental changes that affect vector abundance and behavior are major contributors to malaria transmission in epidemiologically diverse areas across the Amazon Basin. Here we review available data supporting this hypothesis and discuss their implications for current and future malaria intervention policies in the region. Given that locally generated scientific evidence is urgently required to support malaria control interventions in Amazonia, we briefly describe the aims of our current field-oriented malaria research in rural villages and gold-mining enclaves in Peru and a recently opened agricultural settlement in Brazil. PMID:22015425

  14. A New Sensorless Vector Control Method for PMSM Based on a New 4th-Order State-Observer in Stationary Reference Frame with the “Integral-Feedback Type Speed Estimator"

    NASA Astrophysics Data System (ADS)

    Shinnaka, Shinji; Sano, Kousuke

    This paper proposes a new sensorless vector control method for permanent-magnet synchronous motors (PMSM), which uses a new full-order (4th order) state-observer in stationary reference frame combined with the “integral-feedback type speed estimation method". The proposed method can be applied to both of salient and nonsalient PMSM.

  15. The Vector Product Introduction

    E-print Network

    Vickers, James

    The Vector Product 9.4 Introduction In this section we describe how to find the vector product of two vectors. Like the scalar product its definition may seem strange when first met but the definition is chosen because of its many applications. When vectors are multiplied using the vector product the result

  16. Immune Responses against a Single CD8+-T-Cell Epitope Induced by Virus Vector Vaccination Can Successfully Control Trypanosoma cruzi Infection

    Microsoft Academic Search

    Yasushi Miyahira; Yasuhiro Takashima; Seiki Kobayashi; Yasunobu Matsumoto; Tsutomu Takeuchi; Mutsuko Ohyanagi-Hara; Ayako Yoshida; Akihiko Ohwada; Hisaya Akiba; Hideo Yagita; Ko Okumura; Hideoki Ogawa

    2005-01-01

    In order to develop CD8-T-cell-mediated immunotherapy against intracellular infectious agents, vaccina- tion using recombinant virus vectors has become a promising strategy. In this study, we generated recombinant adenoviral and vaccinia virus vectors expressing a single CD8-T-cell epitope, ANYNFTLV, which is derived from a Trypanosoma cruzi antigen. Immunogenicity of these two recombinant virus vectors was confirmed by the detection of ANYNFTLV-specific

  17. Oral multicomponent DNA vaccine delivered by attenuated Salmonella elicited immunoprotection against American trypanosomiasis.

    PubMed

    Cazorla, Silvia I; Matos, Marina N; Cerny, Natacha; Ramirez, Carolina; Alberti, Andrés Sanchez; Bivona, Augusto E; Morales, Celina; Guzmán, Carlos A; Malchiodi, Emilio L

    2015-03-01

    We have reported that attenuated Salmonella (S) carrying plasmids encoding the cysteine protease cruzipain (Cz) protects against Trypanosoma cruzi infection. Here, we determined whether immunoprotection could be improved by the oral coadministration of 3 Salmonella carrying the plasmids that encode the antigens Cz, Tc52, and Tc24. SCz+STc52+STc24-immunized mice presented an increased antibody response against each antigen compared with those in the single antigen-immunized groups, as well as higher trypomastigotes antibody-mediated lyses and cell invasion inhibition compared with controls. SCz+STc52+STc24-immunized and -challenged mice rendered lower parasitemia. Weight loss after infection was detected in all mice except those in the SCz+STc52+STc24 group. Moreover, cardiomyopathy-associated enzyme activity was significantly lower in SCz+STc24+STc52-immunized mice compared with controls. Few or no abnormalities were found in muscle tissues of SCz+STc24+STc52-immunized mice, whereas controls presented with inflammatory foci, necrosis, and amastigote nests. We conclude that a multicomponent approach that targets several invasion and metabolic mechanisms improves protection compared with single-component vaccines. PMID:25160983

  18. Entomopathogenic Fungus as a Biological Control for an Important Vector of Livestock Disease: The Culicoides Biting Midge

    PubMed Central

    Ansari, Minshad Ali; Pope, Edward C.; Carpenter, Simon; Scholte, Ernst-Jan; Butt, Tariq M.

    2011-01-01

    Background The recent outbreak of bluetongue virus in northern Europe has led to an urgent need to identify control measures for the Culicoides (Diptera: Ceratopogonidae) biting midges that transmit it. Following successful use of the entomopathogenic fungus Metarhizium anisopliae against larval stages of biting midge Culicoides nubeculosus Meigen, we investigated the efficacy of this strain and other fungi (Beauveria bassiana, Isaria fumosorosea and Lecanicillium longisporum) as biocontrol agents against adult C. nubeculosus in laboratory and greenhouse studies. Methodology/Findings Exposure of midges to ‘dry’ conidia of all fungal isolates caused significant reductions in survival compared to untreated controls. Metarhizium anisopliae strain V275 was the most virulent, causing a significantly decrease in midge survival compared to all other fungal strains tested. The LT50 value for strain V275 was 1.42 days compared to 2.21–3.22 days for the other isolates. The virulence of this strain was then further evaluated by exposing C. nubeculosus to varying doses (108–1011 conidia m?2) using different substrates (horse manure, damp peat, leaf litter) as a resting site. All exposed adults were found to be infected with the strain V275 four days after exposure. A further study exposed C. nubeculosus adults to ‘dry’ conidia and ‘wet’ conidia (conidia suspended in 0.03% aq. Tween 80) of strain V275 applied to damp peat and leaf litter in cages within a greenhouse. ‘Dry’ conidia were more effective than ‘wet’ conidia, causing 100% mortality after 5 days. Conclusion/Significance This is the first study to demonstrate that entomopathogenic fungi are potential biocontrol agents against adult Culicoides, through the application of ‘dry’ conidia on surfaces (e.g., manure, leaf litter, livestock) where the midges tend to rest. Subsequent conidial transmission between males and females may cause an increased level of fungi-induced mortality in midges thus reducing the incidence of disease. PMID:21264343

  19. Modelling American trypanosomiasis in an endemic zone: application to the initial spread of household infection in the Argentine Chaco.

    PubMed

    Fabrizio, M C; Schweigmann, N J; Bartoloni, N J

    2014-12-01

    The complex dynamics of Trypanosoma cruzi infection (Chagas disease) involves different actors and multiple transmission routes. Based on the information currently available, here, we propose a new and more comprehensive model to better understand the dynamics of the infection. This mathematical deterministic model was formulated considering: (i) the three clinical forms in humans: acute, chronic indeterminate and chronic with determinate pathology, (ii) the three main modes of transmission in the human population: vector-borne, congenital and transfusional, (iii) populations of triatomines and dogs as the main domestic reservoirs of T. cruzi and (iv) open populations. A numerical simulation was also performed to estimate the initial spread of the infection in a typical rural household in the endemic zone of the Argentine Gran Chaco. We also analysed the incidence of infected individuals corresponding to each of the three species (humans/triatomines/dogs) over times until the appearance of the first case in the other species. The model predicts that, in the absence of control measures, a few infected individuals are sufficient for the establishment and dispersion of the infection in all the inhabitants of the household. The model proposed and the results obtained allow describing the consequences of the presence of infected individuals in any of the three species considered in the dynamics and the output of the infection. PMID:24528489

  20. The use of annual killifish in the biocontrol of the aquatic stages of mosquitoes in temporary bodies of fresh water; a potential new tool in vector control

    PubMed Central

    2010-01-01

    Background Mosquitoes that breed in temporary pools in remote areas that dry up seasonally are especially difficult to control through chemical or biological means. The annual killifish has been suggested as a means of eradicating the aquatic stages of mosquitoes in transient pools because they can maintain permanent populations in such habitats by undergoing suspended animation or diapause during the embryonic stages to survive periodic drought. However, very little is known about the predatory activity of annual killifish and their usefulness in mosquito control. Results The annual killifish, Nothobranchius guentheri, native to Tanzania, was used in this investigation. Food preference was tested under laboratory conditions by feeding juvenile killifish with 2nd instar mosquito larvae of Culex quinquefasciatus in the presence of alternative food sources, such as rotifers and chironomid larvae. Semi-field tests were conducted by introduction of hibernating killifish embryos and juvenile fish to artificial ponds in an outdoor open environment that allowed natural oviposition of Cx. quinquefasciatus. Food preference studies show that N. guentheri preferred to prey on mosquito larvae than either chironomid or rotifers. When hibernating killifish embryos were added to ponds simultaneously with the addition of freshwater, the embryos hatched and fed on mosquito larval population resulting in complete elimination of the immature stages. The introduction of juvenile fish to ponds with high density of mosquito larvae resulted in total eradication of the mosquito population due to predation by fish. Complete biocontrol of the mosquito larval population was achieved in the presence of 3 fish per m2 of pond surface area. Conclusions The annual killifish provides yet another tool that may be employed in the eradication diseases carried by mosquitoes through vector control, particularly in temporary bodies of freshwater. The fish can be conveniently transported in the absence of water in the form of hibernating embryos. Once introduced either as embryos or juveniles in ponds, the annual killifish can effectively reduce the larval population because of its aggressive predatory activity. PMID:20492714