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1

Evaluating paratransgenesis as a potential control strategy for African trypanosomiasis.  

PubMed

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

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

2013-01-01

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

Control and surveillance of human African trypanosomiasis.  

PubMed

In the 1960s, it appeared that human African trypanosomiasis (HAT) could be effectively controlled, but by the beginning of the twenty-first century several decades of neglect had led to alarming numbers of reported new cases, with an estimated 300 000 people infected. The World Health Organization (WHO) responded with a series of initiatives aimed at bringing HAT under control again. Since 2001, the pharmaceutical companies that produce drugs for HAT have committed themselves to providing them free of charge to WHO for distribution for the treatment of patients. In addition, funds have been provided to WHO to support national sleeping sickness control programmes to boost control and surveillance of the disease. That, coupled with bilateral cooperation and the work of nongovernmental organizations, helped reverse the upward trend in HAT prevalence. By 2012, the number of reported cases was fewer than 8000. This success in bringing HAT under control led to its inclusion in the WHO Roadmap for eradication, elimination and control of neglected tropical diseases, with a target set to eliminate the disease as a public health problem by 2020. A further target has been set, by countries in which HAT is endemic, to eliminate gambiense HAT by reducing the incidence of infection to zero in a defined geographical area. This report provides information about new diagnostic approaches, new therapeutic regimens and better understanding of the distribution of the disease with high-quality mapping. The roles of human and animal reservoirs and the tsetse fly vectors that transmit the parasites are emphasized. The new information has formed the basis for an integrated strategy with which it is hoped that elimination of gambiense HAT will be achieved. The report also contains recommendations on the approaches that will lead to elimination of the disease. PMID:24552089

2013-01-01

4

How can tsetse population genetics contribute to African trypanosomiasis control?  

PubMed

In sub-Saharan Africa, tsetse transmitted Trypanosomiases have an enormous impact on human health and economic development. Both the World Health Organisation and African countries through the Pan African Tsetse and Trypanosomiasis Eradication Campaign (PATTEC) have recently asserted their determination to rid the sub-continent of these diseases, and it is increasingly recognised that vector control should play an important role. This review mainly focuses on population genetics of tsetse of the palpalis group, the main vectors of sleeping sickness, and reports recent results on tsetse population structure and on measures of gene flow between populations. Implications of these studies for large-scale tsetse control programmes being undertaken in West Africa are important, particularly regarding control strategies (suppression or eradication). PMID:20202905

Solano, Philippe; Ravel, Sophie; de Meeûs, Thierry

2010-05-01

5

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

Microsoft Academic Search

SUMMARY In the Eastern Mediterranean Region of the World Health Organization (WHO), malaria, schisto- somiasis, 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

S. L. Croft; L. Vivas; S. Brooker

6

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

MedlinePLUS

... CDC.gov . Parasites - American Trypanosomiasis (also known as Chagas Disease) Parasites Home Share Compartir Prevention & Control In ... triatomine bugs has significantly decreased the spread of Chagas disease. Further, screening of blood donations for Chagas ...

7

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

Microsoft Academic Search

Climate warming over the next century is expected to have a large impact on the interactions between pathogens and their animal and human hosts. Vector-borne diseases are particularly sensitive to warming because temperature changes can alter vector development rates, shift their geographical distribution and alter transmission dynamics. For this reason, African trypanosomiasis (sleeping sickness), a vector-borne disease of humans and

S. Moore; S. Shrestha; K. W. Tomlinson; H. Vuong

2012-01-01

8

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

PubMed Central

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

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

2002-01-01

9

Improving the cost-effectiveness of visual devices for the control of riverine tsetse flies, the major vectors of human African trypanosomiasis.  

PubMed

Control of the Riverine (Palpalis) group of tsetse flies is normally achieved with stationary artificial devices such as traps or insecticide-treated targets. The efficiency of biconical traps (the standard control device), 1×1 m black targets and small 25×25 cm targets with flanking nets was compared using electrocuting sampling methods. The work was done on Glossina tachinoides and G. palpalis gambiensis (Burkina Faso), G. fuscipes quanzensis (Democratic Republic of Congo), G. f. martinii (Tanzania) and G. f. fuscipes (Kenya). The killing effectiveness (measured as the catch per m(2) of cloth) for small targets plus flanking nets is 5.5-15X greater than for 1 m(2) targets and 8.6-37.5X greater than for biconical traps. This has important implications for the costs of control of the Riverine group of tsetse vectors of sleeping sickness. PMID:21829743

Esterhuizen, Johan; Rayaisse, Jean Baptiste; Tirados, Inaki; Mpiana, Serge; Solano, Philippe; Vale, Glyn A; Lehane, Michael J; Torr, Stephen J

2011-08-01

10

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

PubMed Central

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

2014-01-01

11

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

PubMed

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

2014-04-25

12

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

PubMed Central

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

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

2012-01-01

13

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

PubMed Central

In this survey of recent ecological research on the main vectors of trypanosomiasis in those countries of East, Central and West Africa that are not predominantly French-speaking, the authors, after outlining the distribution of tsetse flies and the type of country in which they occur, discuss the direct and indirect effects of climate on these insects—particularly on their physiological water balance and on pupal fat reserves—and their recent advances into new areas. They review the considerable work that has been done on the resting habits and breeding-sites of different Glossina species, knowledge of which is important for effective control, and research on predators of pupae and adult flies and on the feeding activity of tsetse flies. Means of assessing populations and various factors affecting the size and nutritional status of tsetse flies are also discussed, as is the effect on the fly population of artificial changes in the habitat. Finally, a plea is made for a revision of present methods of land use and stock management, if full advantage is to be taken of achievements in fly control. PMID:13928678

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

1963-01-01

14

Tsetse fly control and trypanosomiasis in Africa, quo vadis?  

PubMed

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

Dräger, N

2011-02-01

15

Human/vector relationships during human African trypanosomiasis: initial screening of immunogenic salivary proteins of Glossina species.  

PubMed

The morbidity and mortality of vector-borne diseases is closely linked to exposure of the human host to vectors. Qualitative and quantitative evaluation of individual exposure to arthropod bites by investigation of the specific immune response to vector saliva would make it possible to monitor individuals at risk of vectorial transmission of pathogens. The objective of this study was to evaluate and compare the antibody (IgG) response to saliva from uninfected Glossina species, vectors, or non-vectors of Trypanosoma brucei gambiense by detecting immunogenic proteins in humans residing in an area endemic for human African trypanosomiasis in the Democratic Republic of Congo. Our results suggest that the immunogenic profiles observed seemed specific to the Glossina species (vector or non-vector species) and to the infectious status of exposed individuals (infected or not infected). This preliminary work tends to support the feasibility of development of an epidemiologic tool based on this antibody response to salivary proteins. PMID:17297044

Poinsignon, Anne; Cornelie, Sylvie; Remoue, Franck; Grébaut, Pascal; Courtin, David; Garcia, Andre; Simondon, Francois

2007-02-01

16

Human African trypanosomiasis.  

PubMed

Human African trypanosomiasis or sleeping sickness is a neglected tropical disease that affects populations in sub-Saharan Africa. The disease is caused by infection with the gambiense and rhodesiense subspecies of the extracellular parasite Trypanosoma brucei, and is transmitted to humans by bites of infected tsetse flies. The disease evolves in two stages, the hemolymphatic and meningoencephalitic stages, the latter being defined by central nervous system infection after trypanosomal traversal of the blood-brain barrier. African trypanosomiasis, which leads to severe neuroinflammation, is fatal without treatment, but the available drugs are toxic and complicated to administer. The choice of medication is determined by the infecting parasite subspecies and disease stage. Clinical features include a constellation of nonspecific symptoms and signs with evolving neurological and psychiatric alterations and characteristic sleep-wake disturbances. Because of the clinical profile variability and insidiously progressive central nervous system involvement, disease staging is currently based on cerebrospinal fluid examination, which is usually performed after the finding of trypanosomes in blood or other body fluids. No vaccine being available, control of human African trypanosomiasis relies on diagnosis and treatment of infected patients, assisted by vector control. Better diagnostic tools and safer, easy to use drugs are needed to facilitate elimination of the disease. PMID:23829907

Lejon, Veerle; Bentivoglio, Marina; Franco, José Ramon

2013-01-01

17

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

Microsoft Academic Search

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

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

18

American trypanosomiasis.  

PubMed

American trypanosomiasis is a parasitic disease caused by the flagellate protozoan Trypanosoma cruzi. Chagas disease is endemic in Latin America, where an estimated 10-14 million people are infected, and an emerging disease in Europe and the USA. Trypanosoma cruzi is transmitted by blood-sucking bugs of the family Reduviidae. Rhodnius prolixus, Panstrongylus megistus, Triatoma infestans, and T. dimidiata are the main vectors in the sylvatic cycle. Non vector-borne transmission includes blood transfusion, congenital and oral transmission, transplantation, and accidental infections. Most cases of acute infection occur in childhood and are usually asymptomatic, although severe myocarditis and meningoencephalitis may occur. Approximately 30% of T. cruzi-infected people will develop the chronic stage of the disease. Chronic chagasic cardiomyopathy is characterized by progressive heart failure, arrhythmias, intraventricular conduction defects, sudden death, and peripheral thromboembolism. Acute exacerbation can occur in individuals with involvement of cellular immunity such as advanced AIDS (acquired immunodeficiency syndrome), and transplant-associated immunosuppression. Neurological involvement may present with encephalitis, meningoencephalitis, or a space-occupying cerebral lesion called chagoma. Chagas disease is a major cause of ischemic stroke in Latin America. Several epidemiological studies have found an association between T. cruzi infection and cardioembolic ischemic stroke. Benznidazole and nifurtimox are the two available trypanocide drugs against T. cruzi. PMID:23829903

Carod-Artal, Francisco Javier

2013-01-01

19

Evaluation of a novel method for controlling bovine trypanosomiasis   

E-print Network

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 ...

Brownlow, Andrew C.

2007-11-27

20

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

PubMed Central

Background In Uganda, Rhodesian sleeping sickness, caused by Trypanosoma brucei rhodesiense, and animal trypanosomiasis caused by T. vivax and T. congolense, are being controlled by treating cattle with trypanocides and/or insecticides. We used a mathematical model to identify treatment coverages required to break transmission when host populations consisted of various proportions of wild and domestic mammals, and reptiles. Methodology/Principal Findings An Ro model for trypanosomiasis was generalized to allow tsetse to feed off multiple host species. Assuming populations of cattle and humans only, pre-intervention Ro values for T. vivax, T. congolense, and T. brucei were 388, 64 and 3, respectively. Treating cattle with trypanocides reduced R0 for T. brucei to <1 if >65% of cattle were treated, vs 100% coverage necessary for T. vivax and T. congolense. The presence of wild mammalian hosts increased the coverage required and made control of T. vivax and T. congolense impossible. When tsetse fed only on cattle or humans, R0 for T. brucei was <1 if 20% of cattle were treated with insecticide, compared to 55% for T. congolense. If wild mammalian hosts were also present, control of the two species was impossible if proportions of non-human bloodmeals from cattle were <40% or <70%, respectively. R0 was <1 for T. vivax only when insecticide treatment led to reductions in the tsetse population. Under such circumstances R0<1 for T. brucei and T. congolense if cattle make up 30% and 55%, respectively of the non-human tsetse bloodmeals, as long as all cattle are treated with insecticide. Conclusions/Significance In settled areas of Uganda with few wild hosts, control of Rhodesian sleeping sickness is likely to be much more effectively controlled by treating cattle with insecticide than with trypanocides. PMID:22616017

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

2012-01-01

21

Ecology of a vector-borne zoonosis in a complex ecosystem: trypanosomiasis in Serengeti, Tanzania   

E-print Network

Unravelling the complexities of a disease with multiple wildlife host and multiple tsetse vector species is no easy task. After over a century of field observations, experimental studies, anecdotal evidence and conjecture, ...

Auty, Harriet K.

2009-01-01

22

Human immunodeficiency virus infection and human African trypanosomiasis: a case-control study in Côte d'Ivoire  

Microsoft Academic Search

To assess the association between human immunodeficiency virus (HIV) infection and human African trypanosomiasis (HAT) in Côte d'Ivoire, West Africa, a cross-sectional case-control study was conducted on 301 HAT patients recruited in the main foci of the country. For each HAT patient, 3 controls, matched for sex, age and residence, were selected. Data relating to socio-demographic factors and potential risk

Honore A. Meda; Felix Doua; Claude Laveissière; Tanoh W. Miezan; Els Gaens; Kari Brattegaard; Aimé de Muynck; Kevin M. De Cock

1995-01-01

23

The history of African trypanosomiasis.  

PubMed

The prehistory of African trypanosomiasis indicates that the disease may have been an important selective factor in the evolution of hominids. Ancient history and medieval history reveal that African trypanosomiasis affected the lives of people living in sub-Saharan African at all times. Modern history of African trypanosomiasis revolves around the identification of the causative agents and the mode of transmission of the infection, and the development of drugs for treatment and methods for control of the disease. From the recent history of sleeping sickness we can learn that the disease can be controlled but probably not be eradicated. Current history of human African trypanosomiasis has shown that the production of anti-sleeping sickness drugs is not always guaranteed, and therefore, new, better and cheaper drugs are urgently required. PMID:18275594

Steverding, Dietmar

2008-01-01

24

The history of African trypanosomiasis  

PubMed Central

The prehistory of African trypanosomiasis indicates that the disease may have been an important selective factor in the evolution of hominids. Ancient history and medieval history reveal that African trypanosomiasis affected the lives of people living in sub-Saharan African at all times. Modern history of African trypanosomiasis revolves around the identification of the causative agents and the mode of transmission of the infection, and the development of drugs for treatment and methods for control of the disease. From the recent history of sleeping sickness we can learn that the disease can be controlled but probably not be eradicated. Current history of human African trypanosomiasis has shown that the production of anti-sleeping sickness drugs is not always guaranteed, and therefore, new, better and cheaper drugs are urgently required. PMID:18275594

Steverding, Dietmar

2008-01-01

25

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

PubMed Central

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, Côte d'Ivoire, the Democratic Republic of the Congo, and Uganda to one of these treatment regimens and followed up for 2 years. RESULTS: Six patients died during treatment, one of whom was on the 7-day regimen, whereas the other five had been on the 14-day regimen (P = 0.2). The response to eflornithine differed markedly between Uganda and other countries. Among new cases in Uganda, the 2-year probability of cure was 73% on the 14-day course compared with 62% on the 7-day regimen (hazard ratio (HR) for treatment failure, 7-day versus 14-day regimen: 1.45, 95% CI: 0.7, 3.1, P = 0.3). Among new cases in Côte d'Ivoire, Congo, and the Democratic Republic of the Congo combined, the 2-year probability of cure was 97% on the 14-day course compared with 86.5% on the 7-day regimen (HR for treatment failure, 7-day vs 14-day: 6.72, 95% confidence interval (CI): 1.5, 31.0, P = 0.003). Among relapsing cases in all four countries, the 2-year probability of cure was 94% with 7 days and 100% with 14 days of treatment. Factors associated with a higher risk of treatment failure were: a positive lymph node aspirate (HR 4.1; 95% CI: 1.8-9.4), a cerebrospinal fluid (CSF) white cell count > or = 100/mm3 (HR 3.5; 95% CI: 1.1-10.9), being treated in Uganda (HR 2.9; 95% CI: 1.4-5.9), and CSF trypanosomes (HR 1.9; 95% CI: 0.9-4.1). Being stuporous on admission was associated with a lower risk of treatment failure (HR 0.18; 95% CI: 0.02-1.4) as was increasing age (HR 0.977; 95% CI: 0.95-1.0, for each additional year of age). DISCUSSION: The 7-day course of eflornithine is an effective treatment of relapsing cases of Gambian trypanosomiasis. For new cases, a 7-day course is inferior to the standard 14-day regimen and cannot be recommended. PMID:11143188

Pépin, J.; Khonde, N.; Maiso, F.; Doua, F.; Jaffar, S.; Ngampo, S.; Mpia, B.; Mbulamberi, D.; Kuzoe, F.

2000-01-01

26

African Trypanosomiasis Gambiense, Italy  

PubMed Central

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

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

2005-01-01

27

Human immunodeficiency virus infection and human African trypanosomiasis: a case-control study in Côte d'Ivoire.  

PubMed

To assess the association between human immunodeficiency virus (HIV) infection and human African trypanosomiasis (HAT) in Côte d'Ivoire, West Africa, a cross-sectional case-control study was conducted on 301 HAT patients recruited in the main foci of the country. For each HAT patient, 3 controls, matched for sex, age and residence, were selected. Data relating to socio-demographic factors and potential risk factors for Trypanosoma brucei gambiense and HIV infections were obtained, and serum samples were collected for HIV-1 and HIV-2 tests. A positive test consisted of enzyme immunoassay reactive to HIV-1, HIV-2 or both and confirmed by a synthetic peptide test or Western blot. Data were analyzed using conditional logistic regression with EGRET software. No statistically significant difference was found between the prevalence of HIV infection in HAT patients and controls (4.3% and 3.5% respectively; crude odds ratio (OR) 1.28, 95% confidence interval (CI) 0.65-2.50). In multivariate analysis, allowance for 5 covariates did not change the association between the 2 infections (adjusted OR 1.27, 95% CI 0.64-2.52). Although this study had limited statistical power, no significant association was found between HIV infection and T.b. gambiense infection in rural Côte d'Ivoire. Studies are needed to determine whether HIV infection influences the clinical course of HAT, a question not addressed in the present study. PMID:8594681

Meda, H A; Doua, F; Laveissière, C; Miezan, T W; Gaens, E; Brattegaard, K; de Muynck, A; De Cock, K M

1995-01-01

28

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

PubMed Central

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

Busvine, J. R.; Pal, R.

1969-01-01

29

Thrust-Vector-Control System  

NASA Technical Reports Server (NTRS)

Control gains computed via matrix Riccati equation. Software-based system controlling aim of gimbaled rocket motor on spacecraft adaptive and optimal in sense it adjusts control gains in response to feedback, according to optimizing algorithm based on cost function. Underlying control concept also applicable, with modifications, to thrust-vector control on vertical-takeoff-and-landing airplanes, control of orientations of scientific instruments, and robotic control systems.

Murray, Jonathan

1992-01-01

30

Twenty-four-hour plasma cortisol and prolactin in human African trypanosomiasis patients and healthy African controls.  

PubMed

We have previously demonstrated that human African trypanosomiasis (sleeping sickness) at the stage of meningoencephalitis results in a major disruption of the circadian rhythmicity of sleep and wakefulness that is proportional to the severity of the disease. This paper examines the corresponding 24-hourly secretion in cortisol and prolactin and compares it with the hourly distribution of sleep composition in infected patients and healthy African subjects. The secretion of cortisol in humans follows a circadian rhythm relatively independent of the sleep-wake cycle, whereas that of prolactin exhibits fluctuations over the 24-hr day that are strongly related to the sleep-wake cycle. After the clinical classification of the patients according to the severity of the disease, hourly blood samples were taken over 24 hr via an indwelling catheter. Plasma cortisol and prolactin were analyzed by radioimmunoassay, and the variations in the hourly concentrations were analyzed for the presence of a potential 24-hr rhythm (circadian). All of the healthy African subjects showed significant circadian rhythms in both cortisol and prolactin secretion, similar to data on humans from temperate regions, and a sleep-related anamnestic afternoon peak of prolactin. Major disruptions in the circadian rhythms of plasma cortisol and prolactin were found in the three patients with the most severe illness, in contrast to the four who were less severely ill and the healthy controls. Thus, it appears that as the disease progresses in severity, major disruptions begin to occur in body circadian rhythms, not only in the sleep-wake cycle as reported elsewhere, but also in cortisol and prolactin secretion, suggesting that sleeping sickness affects the circadian timing system. PMID:7694972

Radomski, M W; Buguet, A; Montmayeur, A; Bogui, P; Bourdon, L; Doua, F; Lonsdorfer, A; Tapie, P; Dumas, M

1995-03-01

31

Solid rocket thrust vector control  

NASA Technical Reports Server (NTRS)

Thrust vector control systems that superimpose a side force on the motor thrust, steering being achieved by the side force causing a moment about the vehicle center of gravity are described. A brief review of thrust vector control systems is presented, and two systems, flexible joint and liquid injection, are treated in detail. Treatment of the flexible-joint thrust vector control system is limited to the design of the flexible joint and its insulation against hot motor gases. Treatment of the liquid injection thrust vector control system is limited to discussion of the injectant, valves, piping, storage tanks, and pressurization system; no evaluation is presented of the nozzle except for (1) the effect of the injectant and erosion at the injection port and (2) the effect of injection on pressure distribution within the nozzle.

1974-01-01

32

Improvements on Restricted Insecticide Application Protocol for Control of Human and Animal African Trypanosomiasis in Eastern Uganda  

PubMed Central

Background African trypanosomes constrain livestock and human health in Sub-Saharan Africa, and aggravate poverty and hunger of these otherwise largely livestock-keeping communities. To solve this, there is need to develop and use effective and cheap tsetse control methods. To this end, we aimed at determining the smallest proportion of a cattle herd that needs to be sprayed on the legs, bellies and ears (RAP) for effective Human and Animal African Trypanosomiasis (HAT/AAT) control. Methodology/Principal finding Cattle in 20 villages were ear-tagged and injected with two doses of diminazene diaceturate (DA) forty days apart, and randomly allocated to one of five treatment regimens namely; no treatment, 25%, 50%, 75% monthly RAP and every 3 month Albendazole drench. Cattle trypanosome re-infection rate was determined by molecular techniques. ArcMap V10.3 was used to map apparent tsetse density (FTD) from trap catches. The effect of graded RAP on incidence risk ratios and trypanosome prevalence was determined using Poisson and logistic random effect models in R and STATA V12.1 respectively. Incidence was estimated at 9.8/100 years in RAP regimens, significantly lower compared to 25.7/100 years in the non-RAP regimens (incidence rate ratio: 0.37; 95% CI: 0.22–0.65; P<0.001). Likewise, trypanosome prevalence after one year of follow up was significantly lower in RAP animals than in non-RAP animals (4% vs 15%, OR: 0.20, 95% CI: 0.08–0.44; P<0.001). Contrary to our expectation, level of protection did not increase with increasing proportion of animals treated. Conclusions/significance Reduction in RAP coverage did not significantly affect efficacy of treatment. This is envisaged to improve RAP adaptability to low income livestock keepers but needs further evaluation in different tsetse challenge, HAT/AAT transmission rates and management systems before adopting it for routine tsetse control programs. PMID:25356758

Muhanguzi, Dennis; Picozzi, Kim; Hatendorf, Jan; Thrusfield, Michael; Welburn, Susan Christina; Kabasa, John David; Waiswa, Charles

2014-01-01

33

The population structure of Glossina fuscipes fuscipes in the Lake Victoria basin in Uganda: implications for vector control  

Microsoft Academic Search

BACKGROUND: Glossina fuscipes fuscipes is the primary vector of trypanosomiasis in humans and livestock in Uganda. The Lake Victoria basin has been targeted for tsetse eradication using a rolling carpet initiative, from west to east, with four operational blocks (3 in Uganda and 1 in Kenya), under a Pan-African Tsetse and Trypanosomiasis Eradication Campaign (PATTEC). We screened tsetse flies from

Chaz Hyseni; Agapitus B Kato; Loyce M Okedi; Charles Masembe; Johnson O Ouma; Serap Aksoy; Adalgisa Caccone

2012-01-01

34

Epidemiology of human African trypanosomiasis  

PubMed Central

Human African trypanosomiasis (HAT), or sleeping sickness, is caused by Trypanosoma brucei gambiense, which is a chronic form of the disease present in western and central Africa, and by Trypanosoma brucei rhodesiense, which is an acute disease located in eastern and southern Africa. The rhodesiense form is a zoonosis, with the occasional infection of humans, but in the gambiense form, the human being is regarded as the main reservoir that plays a key role in the transmission cycle of the disease. The gambiense form currently assumes that 98% of the cases are declared; the Democratic Republic of the Congo is the most affected country, with more than 75% of the gambiense cases declared. The epidemiology of the disease is mediated by the interaction of the parasite (trypanosome) with the vectors (tsetse flies), as well as with the human and animal hosts within a particular environment. Related to these interactions, the disease is confined in spatially limited areas called “foci”, which are located in Sub-Saharan Africa, mainly in remote rural areas. The risk of contracting HAT is, therefore, determined by the possibility of contact of a human being with an infected tsetse fly. Epidemics of HAT were described at the beginning of the 20th century; intensive activities have been set up to confront the disease, and it was under control in the 1960s, with fewer than 5,000 cases reported in the whole continent. The disease resurged at the end of the 1990s, but renewed efforts from endemic countries, cooperation agencies, and nongovernmental organizations led by the World Health Organization succeeded to raise awareness and resources, while reinforcing national programs, reversing the trend of the cases reported, and bringing the disease under control again. In this context, sustainable elimination of the gambiense HAT, defined as the interruption of the transmission of the disease, was considered as a feasible target for 2030. Since rhodesiense HAT is a zoonosis, where the animal reservoir plays a key role, the interruption of the disease’s transmission is not deemed feasible. PMID:25125985

Franco, Jose R; Simarro, Pere P; Diarra, Abdoulaye; Jannin, Jean G

2014-01-01

35

Epidemiology of human African trypanosomiasis.  

PubMed

Human African trypanosomiasis (HAT), or sleeping sickness, is caused by Trypanosoma brucei gambiense, which is a chronic form of the disease present in western and central Africa, and by Trypanosoma brucei rhodesiense, which is an acute disease located in eastern and southern Africa. The rhodesiense form is a zoonosis, with the occasional infection of humans, but in the gambiense form, the human being is regarded as the main reservoir that plays a key role in the transmission cycle of the disease. The gambiense form currently assumes that 98% of the cases are declared; the Democratic Republic of the Congo is the most affected country, with more than 75% of the gambiense cases declared. The epidemiology of the disease is mediated by the interaction of the parasite (trypanosome) with the vectors (tsetse flies), as well as with the human and animal hosts within a particular environment. Related to these interactions, the disease is confined in spatially limited areas called "foci", which are located in Sub-Saharan Africa, mainly in remote rural areas. The risk of contracting HAT is, therefore, determined by the possibility of contact of a human being with an infected tsetse fly. Epidemics of HAT were described at the beginning of the 20th century; intensive activities have been set up to confront the disease, and it was under control in the 1960s, with fewer than 5,000 cases reported in the whole continent. The disease resurged at the end of the 1990s, but renewed efforts from endemic countries, cooperation agencies, and nongovernmental organizations led by the World Health Organization succeeded to raise awareness and resources, while reinforcing national programs, reversing the trend of the cases reported, and bringing the disease under control again. In this context, sustainable elimination of the gambiense HAT, defined as the interruption of the transmission of the disease, was considered as a feasible target for 2030. Since rhodesiense HAT is a zoonosis, where the animal reservoir plays a key role, the interruption of the disease's transmission is not deemed feasible. PMID:25125985

Franco, Jose R; Simarro, Pere P; Diarra, Abdoulaye; Jannin, Jean G

2014-01-01

36

Bovine trypanosome species prevalence and farmers' trypanosomiasis control methods in south-western Uganda.  

PubMed

A cross-sectional study was conducted in Mbarara district, south-western Uganda in May 2012 to determine the burden of African animal trypanosomosis (AAT) in the semi-intensive dairy production systems where pyrethroid acaricides are frequently used in the control of tick-borne diseases (TBDs). A total of 295 cattle blood samples were taken and analysed using a single pair of primers previously designed to amplify internal transcribed spacer (ITS1) of trypanosome ribosomal deoxyribonucleic acid (rDNA). A structured questionnaire was administered to 55 participating livestock farmers to generate data on acaricide and trypanocidal drug usage. The overall prevalence of trypanosome species was 2.4% (95% CI; 1.0% - 4.8%); Trypanosoma vivax was the most predominant species (2.0%; 95% CI; 0.7% - 4.4%). A single mixed infection of T. vivax and Trypanosoma brucei s.l. was detected. All the participating farmers used acaricides for tsetse and TBD control; 89.1% of the acaricides used were pyrethroids. About half of the farmers used trypanocidal drugs, mainly diminazene formulations (Berenil®). Low prevalence of trypanosomes in examined samples is most likely related to the frequent use of pyrethroid insecticides, trypanocides and restricted grazing (paddocking and tethering). These rigorous management practices are geared towards optimising production of exotic dairy breeds kept in this region that are highly susceptible to TBDs and AAT. PMID:25686358

Alingu, Richard A; Muhanguzi, Dennis; MacLeod, Ewan; Waiswa, Charles; Fyfe, Jenna

2014-01-01

37

Human African trypanosomiasis: presence of antibodies to galactocerebrosides.  

PubMed

Improvements were made in the immunodetection of anti-galactocerebroside (anti-GalC) antibody in sera of patients with human African trypanosomiasis by thin-layer chromatography, enzyme-linked immunosorbent assay, and immunoadsorption. Rabbit anti-GalC antibodies were used to standardize these techniques and demonstrate their specificity. Anti-GalC antibodies were found in the sera of 42.8% of 63 patients with human African trypanosomiasis. Thirty-four control subjects living in the same endemic area were also tested. Anti-GalC levels were higher in human African trypanosomiasis patients with neurologic disturbances compared with patients without such disturbances. These antibodies were distributed mainly between the IgG and IgM classes, but 28% of the patients with human African trypanosomiasis had increased IgA levels without anti-GalC antibody activity. PMID:1449206

Amevigbe, M D; Jauberteau-Marchan, M O; Bouteille, B; Doua, F; Breton, J C; Nicolas, J A; Dumas, M

1992-11-01

38

Vaccination against trypanosomiasis  

PubMed Central

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

La Greca, Florencia

2011-01-01

39

Control of malaria and other vector-borne protozoan diseases in the tropics: enduring challenges despite considerable progress and achievements  

PubMed Central

Vector-borne protozoan diseases represent a serious public health challenge, especially in the tropics where poverty together with vector-favorable climates are the aggravating factors. Each of the various strategies currently employed to face these scourges is seriously inadequate. Despite enormous efforts, vaccines—which represent the ideal weapon against these parasitic diseases—are yet to be sufficiently developed and implemented. Chemotherapy and vector control are therefore the sole effective attempts to minimize the disease burden. Nowadays, both strategies are also highly challenged by the phenomenon of drug and insecticide resistance, which affects virtually all interventions currently used. The recently growing support from international organizations and governments of some endemic countries is warmly welcome, and should be optimally exploited in the various approaches to drug and insecticide research and development to overcome the burden of these prevalent diseases, especially malaria, leishmaniasis, Human African Trypanosomiasis (HAT), and Chagas disease. PMID:24401663

2014-01-01

40

Insecticide Resistance and Vector Control  

Microsoft Academic Search

Insecticide resistance has been a problem in all insect groups that serve as vectors of emerging diseases. Although mechanisms by which insecticides become less effective are similar across all vector taxa, each resistance problem is potentially unique and may involve a complex pattern of resistance foci. The main defense against resistance is close surveillance of the susceptibility of vector populations.

William G. Brogdon; Janet C. McAllister

1998-01-01

41

Parameter estimation of vector controlled induction machine  

E-print Network

This thesis deals with the modeling and control of induction machine under indirect vector control with parameter estimation in order to get better field oriented performance. Because of its excellent decoupled control, wide flux weakening region...

Rahman, Tahmid Ur

2002-01-01

42

The Biology and Control of Leishmaniasis Vectors  

PubMed Central

Vector control remains a key component of many anti-leishmaniasis programs and probably will remain so until an effective vaccine becomes available. Technologies similar to those used for control of adult mosquitoes, specifically interior residual sprays and insecticide-treated nets, are currently at the forefront as disease control measures. This article provides a review of literature on the biology and control of sand fly vectors of leishmaniasis in the context of changing disease risks and the realities of modern vector control. The Literature Retrieval System of the Armed Forces Pest Management Board, Washington, DC, was the primary search engine used to review the literature. PMID:20606968

Claborn, David M

2010-01-01

43

Speed sensorless hybrid vector controlled induction motor drive  

Microsoft Academic Search

The paper describes a speed and flux sensorless vector-controlled induction motor drive primarily aimed for electric vehicle type applications. The stator flux oriented drive starts at zero speed in indirect vector control mode, transitions to direct vector control mode as the speed develops, and then transitions back to indirect vector control at zero speed. The vector control uses stator flux

Bimal K. Bose; M. Godoy Simoes; David R. Crecelius; Kausik Rajashekara; R. Martin

1995-01-01

44

[Current therapy of trypanosomiasis].  

PubMed

The authors review the available products used for human african trypanosomiasis (HAT) chemotherapy: pentamidine, suramin, melarsoprol and the new compound DFMO. The administration of pentamidine at the beginning of the nervous stage, when the number of cells in the cerebrospinal fluid do not exceed 20/mn3 is a new approach for HAT treatment. At this time of the disease, patients generally are healthy and the pentamidine therapy avoids the use of the toxic melarsoprol (Arsobal). An alternative protocol for Arsobal therapy (2, 16 mg/kg/d for 10 consecutive days) has been described from pharmacokinetics data to decrease the rate of relapses and the duration of hospital care. Efficacy and tolerance of this new protocol must be evaluated by randomised clinical trials. Preliminary data of clinical trials using short-term DFMO therapy are encouraging. DFMO therapy be less expensive. From its efficacy and tolerance, DFMO is a choice chemotherapy for HAT treatment, especially in the case of resistance to usual trypanocides. Both MLD 73811 and IMOL 881 are new trypanocidal compounds, effective on Trypanosoma brucei rhodesiense and T. b. gambiense. In addition, IMOL 881 is effective on the animal trypanosomes, T. evansi and T. equiperdum. Waiting for the availability of these new products, classical trypanocides remain the basis of HAT treatment. PMID:7496197

Doua, F; Boa Yapo, F

1994-01-01

45

Human African trypanosomiasis: an emerging public health crisis.  

PubMed

There is a dramatic resurgence of human African trypanosomiasis (HAT) in sub-Saharan Africa. T.b. gambiense is spreading epidemically in large areas of Central Africa, especially the Southern Sudan, Congo-Zaire, Angola, Uganda and the Central African Republic. Devastating epidemics of T.b. rhodesiense have occurred in south-eastern Uganda. The causes of the re-emergence of sleeping sickness as a public health problem include widespread civil disturbance and war, declining economies, reduced health financing and the dismantling of disease control programmes. Despite the inevitably fatal outcome without treatment, HAT is often given low priority by donors and national governments. The advances made in diagnosis, treatment and vector control have not been sufficiently implemented. To limit the human impact in some of the poorest communities in Africa, endemic countries will require external support to implement strategies for disease control. Donor agencies, NGOs and mission organisations could play an important role in supporting control efforts. National authorities will need to control and co-ordinate these efforts with assistance from WHO and the international community. PMID:9830201

Smith, D H; Pepin, J; Stich, A H

1998-01-01

46

Management of trypanosomiasis and leishmaniasis  

PubMed Central

Background The current treatments for human African trypanosomiasis (HAT), Chagas disease and leishmaniasis (collectively referred to as the kinetoplastid diseases) are far from ideal but, for some, there has been significant recent progress. For HAT the only advances in treatment over the past two decades have been the introduction of an eflornithine/nifurtimox co-administration and a shorter regime of the old standard melarsoprol. Sources of data PubMed. Areas of Agreement There is a need for new safe, oral drugs for cost-effective treatment of patients and use in control programmes for all the trypanosomatid diseases. Areas of controversy Cutaneous leishmaniasis is not on the agenda and treatments are lagging behind. Growing points There are three compounds in development for the treatment of the CNS stage of HAT: fexinidazole, currently due to entry into phase II clinical studies, a benzoxaborole (SCYX-7158) in phase I trials and a diamidine derivative (CPD-0802), in advanced pre-clinical development. For Chagas disease, two anti-fungal triazoles are now in clinical trial. In addition, clinical studies with benznidazole, a drug previously recommended only for acute stage treatment, are close to completion to determine the effectiveness in the treatment of early chronic and indeterminate Chagas disease. For visceral leishmaniasis new formulations, therapeutic switching, in particular AmBisome, and the potential for combinations of established drugs have significantly improved the opportunities for the treatment in the Indian subcontinent, but not in East Africa. Areas timely for developing research Improved diagnostic tools are needed to support treatment, for test of cure in clinical trials and for monitoring/surveillance of populations in control programmes. PMID:23137768

Barrett, Michael P.; Croft, Simon L.

2012-01-01

47

The effects of trypanosomiasis on rural economy*  

PubMed Central

Trypanosomiasis, both of humans and of livestock, is one of the most important factors restricting economic development in Africa today. The present paper outlines how this disease is limiting agricultural, veterinary and forestry development in the Sudan, Bechuanaland and West Africa. The present tsetse-fly distribution is reviewed. Glossina palpalis and G. morsitans occur in the south Sudan and G. morsitans in the Ngamiland district of Bechuanaland; G. morsitans, G. palpalis and G. tachinoides are the most important species in West Africa. These tsetse flies have altered the cattle distribution in all three regions and, in addition to causing widespread disease, have created local overstocking problems in the tsetse-free grazing areas, and have enforced nomadism on breeding herds and economic loss in slaughter cattle along the trade cattle routes in West Africa. Human trypanosomiasis is not now such an urgent problem and public health measures have led to its control in all three areas. Increased agricultural development, which can be a successful and economic method of reclaiming land from tsetse flies, must be intensified in all three areas. Forest conservation policy comes into conflict with tsetse control measures only in West Africa. Detailed tsetse-fly surveys and research, on which future plans can be firmly based, are now urgently required. ImagesFIG. 6 PMID:14001093

Wilson, S. G.; Morris, K. R. S.; Lewis, I. J.; Krog, E.

1963-01-01

48

MODEL PREDICTIVE CONTROL OF A THRUST-VECTORED FLIGHT CONTROL  

E-print Network

and Pado, 2000) and a helicopter experi- ment in (Wan and Bogdanov, 2001). In (Singh and Fuller, 2001), MPCMODEL PREDICTIVE CONTROL OF A THRUST-VECTORED FLIGHT CONTROL EXPERIMENT William B. Dunbar ,1 Mark B ducted fan, a thrust-vectored flight experiment. A real-time trajectory generation software based

Murray, Richard M.

49

Pharmacology of existing drugs for animal trypanosomiasis.  

PubMed

Lack of much interest by the pharmaceutical industry to venture into development of new antitrypanosomal drugs has been a major stimulus to an intensification of research into the few existing drugs. Those indicated for animal trypanosomiasis include: isometamidium, homidium and diminazene, used primarily against Trypanosoma congolense, T. vivax and T. brucei; and quinapyramine, mainly indicated for use against T. evansi infections. A great deal of research effort has focused on development of pharmacological and parasitological methodologies, which have considerably advanced our understanding on the efficacy, resistance, disposition and toxicological mechanisms of these drugs. While a clinical breakthrough has been made in the recent past, in the field of chemotherapy of T. evansi infections by the introduction of a new arsenic compound, melarsenoxide cysteamine, chemotherapy of T. simiae infections in pigs still remains a major challenge because the existing drugs are either ineffective or too toxic for economic use. Further research into the existing drugs is a prerequisite for their optimal usage in the overall effort of improving animal health and productivity through control of trypanosomiasis. PMID:7902656

Kinabo, L D

1993-09-01

50

Injection module thrust vector control  

NASA Technical Reports Server (NTRS)

A three-axis controlled Injection Module propelled by a Star 48 solid rocket motor has been considered for use as a final 'kick' stage to supplement the Inertial Upper Stage in a proposed launch option for the Galileo and International Solar Polar missions. A flight control law for the Injection Module is developed. A position plus rate control law is considered, with integral, path guidance, and derived rate terms added for improved pointing accuracy and fuel efficiency. Selection of control gains is accomplished with the help of analytical limit cycle expressions and verified by computer simulation of the closed loop system. A computer simulation of the flight control system is built around a rigid spacecraft model with gyro dynamics and thruster delays included. Models for pitch/yaw/roll disturbance torques are included. Through simple gain changes the proposed flight control law is shown to accommodate the widely different mass properties of the Galileo and International Solar Polar spacecraft. Pointing accuracies of better than the desired 0.2 degrees are achieved.

Bell, C. E.

1984-01-01

51

Control of Chagas disease vectors  

Microsoft Academic Search

Most Latin American countries are making dramatic pro- gress in controlling Chagas disease, through a series of na- tional and international initiatives focusing on elimination of domestic populations of Triatominae, improved screening of blood donors, and clinical support and treatment of per- sons infected with Trypanosoma cruzi. Some countries, parti- cularly Uruguay, Chile and Brazil, are sufficiently advanced in their

JM Ramsey; CJ Schofield

2003-01-01

52

Mathematical models of human african trypanosomiasis epidemiology.  

PubMed

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

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

2015-03-01

53

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

PubMed Central

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

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

2013-01-01

54

Glossina fuscipes populations provide insights for human African trypanosomiasis transmission in Uganda.  

PubMed

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

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

2013-08-01

55

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

PubMed

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

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

2013-06-01

56

Ascent thrust vector control system test  

NASA Technical Reports Server (NTRS)

Testing of the Ascent Thrust Vector Control System in support of the Ares 1-X program at the Marshall Space Flight Center in Huntsville, Alabama. This image is extracted from a high definition video file and is the highest resolution available

2008-01-01

57

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...

58

Chagas disease vector control in Central America  

Microsoft Academic Search

As the Southern Cone Initiative proceeds steadily towards eradication of Triatoma infestans, there is increasing interest in applying similar approaches to control Chagas disease vectors in Mexico, Central America and countries of the Andean Pact. Here, Chris Schofield and Jean-Pierre Dujardin discuss the technical feasibility of such an approach.

C. J Schofield; J-P Dujardin

1997-01-01

59

Hot gas thrust vector control motor  

Microsoft Academic Search

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

Michel Berdoyes; Russell A. Ellis

1992-01-01

60

Thrust Vector Control using movable probes  

NASA Technical Reports Server (NTRS)

A study was undertaken to determine if movable probes or struts positioned in the nozzle can be used to provide Thrust Vector Control of the Space Shuttle Solid Rocket Booster. The study employed CFD to determine estimates of the shock standoff distance from the probe. An empirical correlation was used to construct the shock shape and the pressure distribution generated by the probe. The TVC performance for a single and multiple number of probes was then used to determine requirements for a maximum thrust angle offset of 7.5 degrees. Consideration was given to what materials would be suitable for the probe and if active cooling is required. Based on the performance analysis and thermal requirements, a Probe Thrust Vector Control (PTVC) system was sized. Indications are that a PTVC system weight is in the 1500 1bm weight range, compared to the existing weight of 7500 1bm for the SRB nozzle gimble system.

Cavalleri, Robert; Tiarn, Weihnurng; Readey, Harvey

1990-01-01

61

Vector control of induction motor with fuzzy PI controller  

Microsoft Academic Search

A description is presented of the fuzzy proportional-plus-integral controller for the vector control system of an induction motor, and the performance of the system using this controller is discussed. The theoretical process of the fuzzy inference and the guide to a design of the controller are presented. This controller is applied to the laboratory model drive system with 0.75 kW

Ichiro Miki; Naoshi Nagai; Sakae Nishiyama; Tetsuo Yamada

1991-01-01

62

Human African trypanosomiasis–neurologicalaspects  

Microsoft Academic Search

Human African Trypanosomiasis\\u000a (HAT),which is also\\u000a known as sleeping sickness, is a\\u000a major cause of death and disability\\u000a in 36 countries in sub-Saharan\\u000a Africa. The disease is caused by the\\u000a protozoan parasite of the Trypanosoma\\u000a genus which is transmitted\\u000a by the bite of the tsetse fly. The\\u000a two types of HAT, the East African\\u000a form due to Trypanosoma b.rhodesiensei (T.

Peter G. E. Kennedy

2006-01-01

63

40 CFR 258.22 - Disease vector control.  

Code of Federal Regulations, 2011 CFR

...CONTINUED) SOLID WASTES CRITERIA FOR MUNICIPAL SOLID WASTE LANDFILLS Operating Criteria § 258.22 Disease vector control...or operators of all MSWLF units must prevent or control on-site populations of disease vectors using techniques...

2011-07-01

64

40 CFR 258.22 - Disease vector control.  

Code of Federal Regulations, 2014 CFR

...CONTINUED) SOLID WASTES CRITERIA FOR MUNICIPAL SOLID WASTE LANDFILLS Operating Criteria § 258.22 Disease vector control...or operators of all MSWLF units must prevent or control on-site populations of disease vectors using techniques...

2014-07-01

65

40 CFR 258.22 - Disease vector control.  

Code of Federal Regulations, 2012 CFR

...CONTINUED) SOLID WASTES CRITERIA FOR MUNICIPAL SOLID WASTE LANDFILLS Operating Criteria § 258.22 Disease vector control...or operators of all MSWLF units must prevent or control on-site populations of disease vectors using techniques...

2012-07-01

66

40 CFR 258.22 - Disease vector control.  

Code of Federal Regulations, 2010 CFR

...CONTINUED) SOLID WASTES CRITERIA FOR MUNICIPAL SOLID WASTE LANDFILLS Operating Criteria § 258.22 Disease vector control...or operators of all MSWLF units must prevent or control on-site populations of disease vectors using techniques...

2010-07-01

67

40 CFR 258.22 - Disease vector control.  

Code of Federal Regulations, 2013 CFR

...CONTINUED) SOLID WASTES CRITERIA FOR MUNICIPAL SOLID WASTE LANDFILLS Operating Criteria § 258.22 Disease vector control...or operators of all MSWLF units must prevent or control on-site populations of disease vectors using techniques...

2013-07-01

68

Vector control of induction motor without shaft encoder  

Microsoft Academic Search

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

T. Ohtani; N. Takada; K. Tanaka

1989-01-01

69

Flexible joints for thrust vector control  

NASA Technical Reports Server (NTRS)

Flexible joints have been used to achieve thrust vector control over a wide range of sizes of nozzles and have been demonstrated successfully in bench tests and static firings, and are operational on two motors. From these many joints the problems of flexible joints have been defined as establishment of the movable nozzle envelope, definition of the actuation power requirements, definition of the mechanical properties of joint materials, adhesive bonding, test methods, and quality control. These data and problem solutions are contained in a large number of reports. Data relating to joint configuration, design requirements, materials selection, joint design, structural analysis, manufacture, and testing are summarized.

Woodberry, R. F. H.

1975-01-01

70

Electromechanical actuation for thrust vector control applications  

NASA Technical Reports Server (NTRS)

The advanced launch system (ALS), 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. An electromechanical actuation (EMA) system is being developed as an attractive alternative to the hydraulic systems. 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. 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 thrust vector control (TVC) system. The EMA system and work proposed for the future are discussed.

Roth, Mary Ellen

1990-01-01

71

Controlling Vector Bessel Beams with Metasurfaces  

NASA Astrophysics Data System (ADS)

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.

Pfeiffer, Carl; Grbic, Anthony

2014-10-01

72

MODEL PREDICTIVE CONTROL OF A THRUST-VECTORED FLIGHT CONTROL  

E-print Network

MODEL PREDICTIVE CONTROL OF A THRUST-VECTORED FLIGHT CONTROL EXPERIMENT William B. Dunbar ,1 Mark B Author to whom correspondence should be addressed, email: dunbar@cds.caltech.edu. Fig. 1. Caltech ducted the computational demand of attempting to use MPC with first principles-based models. Following the large number

Dunbar, William

73

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

PubMed Central

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

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

74

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

PubMed

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

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

75

The Biological Control of the Malaria Vector  

PubMed Central

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

Kamareddine, Layla

2012-01-01

76

Electromechanical actuation for thrust vector control applications  

NASA Technical Reports Server (NTRS)

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.

Roth, Mary Ellen

1990-01-01

77

Using Cell Phones for Mosquito Vector Surveillance and Control  

E-print Network

Using 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 the use of cell phones for field capture and rapid transfer of mosquito vector surveillance data

Bieman, James M.

78

The generalized theory of indirect vector control for AC machines  

Microsoft Academic Search

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

S. Ogasawara; H. Akagi; A. Nabae

1988-01-01

79

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

Microsoft Academic Search

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

Yifan Zhao; Thomas A. Lipo

1995-01-01

80

Thrust Vector Control for Nuclear Thermal Rockets  

NASA Technical Reports Server (NTRS)

Future space missions may use Nuclear Thermal Rocket (NTR) stages for human and cargo missions to Mars and other destinations. The vehicles are likely to require engine thrust vector control (TVC) to maintain desired flight trajectories. This paper explores requirements and concepts for TVC systems for representative NTR missions. Requirements for TVC systems were derived using 6 degree-of-freedom models of NTR vehicles. Various flight scenarios were evaluated to determine vehicle attitude control needs and to determine the applicability of TVC. Outputs from the models yielded key characteristics including engine gimbal angles, gimbal rates and gimbal actuator power. Additional factors such as engine thrust variability and engine thrust alignment errors were examined for impacts to gimbal requirements. Various technologies are surveyed for TVC systems for the NTR applications. A key factor in technology selection is the unique radiation environment present in NTR stages. Other considerations including mission duration and thermal environments influence the selection of optimal TVC technologies. Candidate technologies are compared to see which technologies, or combinations of technologies best fit the requirements for selected NTR missions. Representative TVC systems are proposed and key properties such as mass and power requirements are defined. The outputs from this effort can be used to refine NTR system sizing models, providing higher fidelity definition for TVC systems for future studies.

Ensworth, Clinton B. F.

2013-01-01

81

Paratransgenic Control of Vector Borne Diseases  

PubMed Central

Conventional methodologies to control vector borne diseases with chemical pesticides are often associated with environmental toxicity, adverse effects on human health and the emergence of insect resistance. In the paratransgenic strategy, symbiotic or commensal microbes of host insects are transformed to express gene products that interfere with pathogen transmission. These genetically altered microbes are re-introduced back to the insect where expression of the engineered molecules decreases the host's ability to transmit the pathogen. We have successfully utilized this strategy to reduce carriage rates of Trypanosoma cruzi, the causative agent of Chagas disease, in the triatomine bug, Rhodnius prolixus, and are currently developing this methodology to control the transmission of Leishmania donovani by the sand fly Phlebotomus argentipes. Several effector molecules, including antimicrobial peptides and highly specific single chain antibodies, are currently being explored for their anti-parasite activities in these two systems. In preparation for eventual field use, we are actively engaged in risk assessment studies addressing the issue of horizontal gene transfer from the modified bacteria to environmental microbes. PMID:22110385

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

2011-01-01

82

Rhodesian trypanosomiasis in a splenectomized patient.  

PubMed

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

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

1999-09-01

83

LOW RF CONTROL FEEDBACK AND IQ VECTOR MODULATOR COMPENSATION FUNCTIONS.  

E-print Network

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

Brookhaven National Laboratory

84

Vector control of induction motor without shaft encoder  

Microsoft Academic Search

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

Tsugutoshi Ohtani; Noriyuki Takada; Koji Tanaka

1992-01-01

85

Space vector based current control schemes for voltage source inverters  

Microsoft Academic Search

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

D. Wuest; F. Jenni

1993-01-01

86

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

PubMed

Arthropod-borne virus (arbovirus) diseases (ABVDs) remain major threats to human health and well-being and, as an epidemiologic group, inflict an unacceptable health and economic burden on humans and animals, including livestock. The developed world has been fortunate to have escaped much of the burden that arboviruses and their arthropod vectors inflict on humans in disease endemic countries, but the introduction and rapid spread of West Nile virus in the Western Hemisphere demonstrated that we can no longer be complacent in the face of these emerging and resurging vector-borne diseases. Unfortunately, as the burdens and threats of ABVDs have increased, the U.S. and international public health capacity to address them has decreased. Vaccines are not available for most of these agents. Previously successful strategies to control ABVDs emphasized vector control, but source reduction and vector control strategies using pesticides have not been sustainable. New insights into vector biology and vector pathogen interactions, and the novel targets that likely will be forthcoming in the vector post-genomics era, provide new targets and opportunities for vector control and disease reduction programs. These findings and approaches must be incorporated into existing strategies if we are to control these important pathogens. PMID:16358423

Beaty, B J

2005-01-01

87

A vector control technique for medium voltage multilevel inverters  

Microsoft Academic Search

This paper presents a switching strategy for multilevel cascade inverters, based on the space vector theory. The proposed switching strategy generates a voltage vector with very low harmonic distortion and reduced switching frequency. This new control method is an attractive alternative to the classic multilevel PWM techniques considering the following aspects: (i) voltage and current THD, (ii) range of linear

J. Rodriguez; P. Correa; L. Moran

2001-01-01

88

A vector control technique for medium-voltage multilevel inverters  

Microsoft Academic Search

This paper presents a switching strategy for multilevel cascade inverters, based on the space-vector theory. The proposed switching strategy generates a voltage vector with very low harmonic distortion and reduced switching frequency. This new control method is an attractive alternative to the classic multilevel pulsewidth modulation techniques considering the following aspects: (1) voltage and current total harmonic distortion; (2) range

José Rodríguez; Luis Morán; Pablo Correa; Cesar Silva

2002-01-01

89

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

PubMed

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

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

2013-01-01

90

The distribution of the vectors of African pathogenic trypanosomes*  

PubMed Central

The author lists the species, subspecies and races of tsetse fly now recognized in three morphologically distinct groups. The distribution of each group is mapped and described in relation to climate and vegetation, with some indication of the part played by past climates and orogenies in determining the modern pattern. The importance of different species as vectors of human or bovine trypanosomiasis, or both, is noted, and examples are given of the part played by human settlement as a secondary limiting factor. The author suggests that many modern problems of control are the consequences of the recent invasion of the African ecosystem by the outside world. Although there are local exceptions, the broad pattern of Glossina distribution has not been significantly changed by the entomological approach to the trypanosomiasis problem. PMID:13958704

Ford, J.

1963-01-01

91

Hovering control of vectored thrust aerial vehicles  

Microsoft Academic Search

In this paper, a vectored thrust aerial vehicle( VTAV) that has three ducted fans is considered. Since ducted fans are powerful and effective in providing lift, they are suitable for thrusters of UAVs, but modeling their aerodynamic effects such as ram drag is very difficult. The VTAV has one ducted fan fixed to its body and two ducted fans that

Makoto Kumon; Jayantha Katupitiya

2010-01-01

92

Space vector PWM control of a split-phase induction machine using the vector classification technique  

Microsoft Academic Search

A new and effective space vector PWM control of six-phase voltage source inverters fed split-phase induction motors is presented in this paper. The proposed approach is based on three-phase space vector modulation (SVM) techniques, thereby, it inherently eliminates the 5th, 7th, 17th, 19th, …harmonic currents without extensive computations. Furthermore, the paper utilizes a classification algorithm for the implementation of the

A. R. Bakhshai; G. Joos; H. Jin

1998-01-01

93

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...

94

The population structure of Glossina fuscipes fuscipes in the Lake Victoria basin in Uganda: implications for vector control  

PubMed Central

Background Glossina fuscipes fuscipes is the primary vector of trypanosomiasis in humans and livestock in Uganda. The Lake Victoria basin has been targeted for tsetse eradication using a rolling carpet initiative, from west to east, with four operational blocks (3 in Uganda and 1 in Kenya), under a Pan-African Tsetse and Trypanosomiasis Eradication Campaign (PATTEC). We screened tsetse flies from the three Ugandan PATTEC blocks for genetic diversity at 15 microsatellite loci from continental and offshore populations to provide empirical data to support this initiative. Methods We collected tsetse samples from 11 sites across the Lake Victoria basin in Uganda. We performed genetic analyses on 409 of the collected tsetse flies and added data collected for 278 individuals in a previous study. The flies were screened across 15 microsatellite loci and the resulting data were used to assess the temporal stability of populations, to analyze patterns of genetic exchange and structuring, to estimate dispersal rates and evaluate the sex bias in dispersal, as well as to estimate demographic parameters (NE and NC). Results We found that tsetse populations in this region were stable over 4-16 generations and belong to 4 genetic clusters. Two genetic clusters (1 and 2) corresponded approximately to PATTEC blocks 1 and 2, while the other two (3 and 4) fell within PATTEC block 3. Island populations grouped into the same genetic clusters as neighboring mainland sites, suggesting presence of gene flow between these sites. There was no evidence of the stretch of water separating islands from the mainland forming a significant barrier to dispersal. Dispersal rates ranged from 2.5?km per generation in cluster 1 to 14?km per generation in clusters 3 and 4. We found evidence of male-biased dispersal. Few breeders are successfully dispersing over large distances. Effective population size estimates were low (33–310 individuals), while census size estimates ranged from 1200 (cluster 1) to 4100 (clusters 3 and 4). We present here a novel technique that adapts an existing census size estimation method to sampling without replacement, the scheme used in sampling tsetse flies. Conclusion Our study suggests that different control strategies should be implemented for the three PATTEC blocks and that, given the high potential for re-invasion from island sites, mainland and offshore sites in each block should be targeted at the same time. PMID:23036153

2012-01-01

95

Thrust vector control for the Space Shuttle Solid Rocket Motor  

NASA Technical Reports Server (NTRS)

Thrust vector control (TVC) for the Space Shuttle Solid Rocket Motor (SRM) is obtained by omniaxis vectoring of the nozzle. The development and integration of the system are under the cognizance of Marshall Space Flight Center (MSFC). The nozzle and flexible bearing have been designed and will be built by Thiokol Corporation/Wasatch Division. The vector requirements of the system, the impact of multiple reuse on the components, and the unique problems associated with a large flexible bearing are discussed. The design details of each of the major TVC subcomponents are delineated. The subscale bearing development program and the overall development schedule also are presented.

Counter, D. N.; Brinton, B. C.

1975-01-01

96

Parallel and vector computation for stochastic optimal control applications  

NASA Technical Reports Server (NTRS)

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.

Hanson, F. B.

1989-01-01

97

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

PubMed Central

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

2013-01-01

98

Implementation of a new fuzzy vector control of induction motor.  

PubMed

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

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

2014-05-01

99

Robust nonlinear control of vectored thrust aircraft  

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

100

Support Vector Machines in Fault Tolerance Control  

NASA Astrophysics Data System (ADS)

This paper presents a new approach for quality monitoring of on-line molded parts in the context of an injection molding problem using Support Vector Machines (SVMs). While the main goal in the industrial framework is to automatically calculate the setpoints, a less important task is to classify plastic molded parts defects efficiently in order to assess multiple quality characteristics. The paper presents a comparison of the performance assessment of SVMs and RBF neural networks as part quality monitoring tools by analyzing complete data patterns. Results show that the classification model using SVMs presents slightly better performance than RBF neural networks mainly due to the superior generalization of the SVMs in high-dimensional spaces. Particularly, when RBF kernels are used, the accuracy of the task increases thus leading to smaller error rates. Besides, the optimization method is a constrained quadratic programming, which is a well studied and understood mathematical programming technique.

Ribeiro, Bernardete

2002-09-01

101

Sensorless vector and speed control of brushless motor drives  

Microsoft Academic Search

In the present paper an approach is presented to the speed control of permanent magnet synchronous motors without mechanical transducers. The rotor position, which is an essential component of any vector control scheme, is calculated through the instantaneous stator flux position and an estimated value of the load angle. A closed-loop state observer is implemented to compute the speed feedback

A. Consoli; S. Musumeci; A. Raciti; A. Testa

1994-01-01

102

Spray characterization of ULV sprayers typically used in vector control  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

103

Dengue in Cape Verde: vector control and vaccination  

E-print Network

In 2009, for the first time in Cape Verde, an outbreak of dengue was reported and over twenty thousand people were infected. Only a few prophylactic measures were taken. The effects of vector control on disease spreading, such as insecticide (larvicide and adulticide) and mechanical control, as well as an hypothetical vaccine, are estimated through simulations with the Cape Verde data.

Rodrigues, Helena Sofia; Torres, Delfim F M

2012-01-01

104

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

PubMed Central

Many infections can be transmitted between animals and humans. The epidemiological roles of different species can vary from important reservoirs to dead-end hosts. Here, we present a method to identify transmission cycles in different combinations of species from field data. We used this method to synthesise epidemiological and ecological data from Bipindi, Cameroon, a historical focus of gambiense Human African Trypanosomiasis (HAT, sleeping sickness), a disease that has often been considered to be maintained mainly by humans. We estimated the basic reproduction number of gambiense HAT in Bipindi and evaluated the potential for transmission in the absence of human cases. We found that under the assumption of random mixing between vectors and hosts, gambiense HAT could not be maintained in this focus without the contribution of animals. This result remains robust under extensive sensitivity analysis. When using the distributions of species among habitats to estimate the amount of mixing between those species, we found indications for an independent transmission cycle in wild animals. Stochastic simulation of the system confirmed that unless vectors moved between species very rarely, reintroduction would usually occur shortly after elimination of the infection from human populations. This suggests that elimination strategies may have to be reconsidered as targeting human cases alone would be insufficient for control, and reintroduction from animal reservoirs would remain a threat. Our approach is broadly applicable and could reveal animal reservoirs critical to the control of other infectious diseases. PMID:23341760

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

2013-01-01

105

A Quasioptical Vector Interferometer for Polarization Control  

NASA Technical Reports Server (NTRS)

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.

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

2005-01-01

106

Chemotherapy of human African trypanosomiasis: current and future  

E-print Network

Chemotherapy of human African trypanosomiasis: current and future prospects Alan H. Fairlamb for the development of safer, effective drugs are discussed. The chemotherapy of human African trypanosomiasis (HAT research over the past century has yielded only four clinically approved drugs (Figure 1), three of which

Schnaufer, Achim

107

Thrust vector control by liquid injection for solid propellant rockets  

NASA Technical Reports Server (NTRS)

In liquid injection thrust vector control, a rocket jet is deflected for steering purposed by injecting a liquid into the nozzle exit cone. The liquid is preferably both dense and reactive so that it adds mass and energy and generates shocks in the supersonic exhaust. This behavior increases thrust in the affected part of the jet producing not only a side force for steering but an addition to axial thrust. This paper presents a summary of current liquid injection thrust vector control technology, including procedures for design, development, analysis, testing and evaluation, together with supporting data and references.

Zeamer, R. J.

1975-01-01

108

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 ...

109

Space vector modulated and vector controlled three-level four-wire unidirectional ac-dc-ac converter  

Microsoft Academic Search

This paper presents a unidirectional neutral-point-clamped three-level four-wire AC-DC-AC converter topology and studies how space vector modulation and vector control can be applied to the converter. The modulator is based on standard complex plane space vector modulation and the zero-sequence voltage space is treated as an offset. The zero-sequence offset is realized by proper weighting of redundant vectors of the

Jarno Alahuhtala; Heikki Tuusa

2008-01-01

110

[Blood levels of protein markers of inflammation and nutrition in the meningo-encephalitis phase of human African trypanosomiasis].  

PubMed

Two acute phase proteins; C-reactive protein and acid alpha 1-glycoprotein and three nutritional markers; prealbumin, retinol binding protein and transferrin have been evaluated in 8 patients suffering from trypanosomiasis in meningoencephalitic state and compared to those obtained from 15 normal control subjects. Findings show a markly decrease of nutritional markers without change of sera acute phase proteins. We concluded that in meningo-encephalitic state of human african trypanosomiasis, denutrition was a major biological or clinical feature in association with lymphoid cells stimulation as revealed by beta 2-M levels. PMID:9289245

Monnet, D; Lonsdorfer, A; Pénali, K; Valéro, D; Doua, F; Bogui, P; Yapo, A E

1997-01-01

111

A Literature Review of Economic Evaluations for a Neglected Tropical Disease: Human African Trypanosomiasis (“Sleeping Sickness”)  

PubMed Central

Human African trypanosomiasis (HAT) is a disease caused by infection with the parasite Trypanosoma brucei gambiense or T. b. rhodesiense. It is transmitted to humans via the tsetse fly. Approximately 70 million people worldwide were at risk of infection in 1995, and approximately 20,000 people across Africa are infected with HAT. The objective of this review was to identify existing economic evaluations in order to summarise cost-effective interventions to reduce, control, or eliminate the burden of HAT. The studies included in the review were compared and critically appraised in order to determine if there were existing standardised methods that could be used for economic evaluation of HAT interventions or if innovative methodological approaches are warranted. A search strategy was developed using keywords and was implemented in January 2014 in several databases. The search returned a total of 2,283 articles. After two levels of screening, a total of seven economic evaluations were included and underwent critical appraisal using the Scottish Intercollegiate Guidelines Network (SIGN) Methodology Checklist 6: Economic Evaluations. Results from the existing studies focused on the cost-effectiveness of interventions for the control and reduction of disease transmission. Modelling was a common method to forecast long-term results, and publications focused on interventions by category, such as case detection, diagnostics, drug treatments, and vector control. Most interventions were considered cost-effective based on the thresholds described; however, the current treatment, nifurtomix-eflornithine combination therapy (NECT), has not been evaluated for cost-effectiveness, and considerations for cost-effective strategies for elimination have yet to be completed. Overall, the current evidence highlights the main components that play a role in control; however, economic evaluations of HAT elimination strategies are needed to assist national decision makers, stakeholders, and key funders. These analyses would be of use, as HAT is currently being prioritized as a neglected tropical disease (NTD) to reach elimination by 2020. PMID:25654605

Sutherland, C. Simone; Yukich, Joshua; Goeree, Ron; Tediosi, Fabrizio

2015-01-01

112

A literature review of economic evaluations for a neglected tropical disease: human African trypanosomiasis ("sleeping sickness").  

PubMed

Human African trypanosomiasis (HAT) is a disease caused by infection with the parasite Trypanosoma brucei gambiense or T. b. rhodesiense. It is transmitted to humans via the tsetse fly. Approximately 70 million people worldwide were at risk of infection in 1995, and approximately 20,000 people across Africa are infected with HAT. The objective of this review was to identify existing economic evaluations in order to summarise cost-effective interventions to reduce, control, or eliminate the burden of HAT. The studies included in the review were compared and critically appraised in order to determine if there were existing standardised methods that could be used for economic evaluation of HAT interventions or if innovative methodological approaches are warranted. A search strategy was developed using keywords and was implemented in January 2014 in several databases. The search returned a total of 2,283 articles. After two levels of screening, a total of seven economic evaluations were included and underwent critical appraisal using the Scottish Intercollegiate Guidelines Network (SIGN) Methodology Checklist 6: Economic Evaluations. Results from the existing studies focused on the cost-effectiveness of interventions for the control and reduction of disease transmission. Modelling was a common method to forecast long-term results, and publications focused on interventions by category, such as case detection, diagnostics, drug treatments, and vector control. Most interventions were considered cost-effective based on the thresholds described; however, the current treatment, nifurtomix-eflornithine combination therapy (NECT), has not been evaluated for cost-effectiveness, and considerations for cost-effective strategies for elimination have yet to be completed. Overall, the current evidence highlights the main components that play a role in control; however, economic evaluations of HAT elimination strategies are needed to assist national decision makers, stakeholders, and key funders. These analyses would be of use, as HAT is currently being prioritized as a neglected tropical disease (NTD) to reach elimination by 2020. PMID:25654605

Sutherland, C Simone; Yukich, Joshua; Goeree, Ron; Tediosi, Fabrizio

2015-02-01

113

Vector-borne disease problems in rapid urbanization: new approaches to vector control.  

PubMed

Owing to population growth, poor levels of hygiene, and increasing urban poverty, the urban environment in many developing countries is rapidly deteriorating. Densely packed housing in shanty towns or slums and inadequate drinking-water supplies, garbage collection services, and surface-water drainage systems combine to create favourable habitats for the proliferation of vectors and reservoirs of communicable diseases. As a consequence, vector-borne diseases such as malaria, lymphatic filariasis and dengue are becoming major public health problems associated with rapid urbanization in many tropical countries. The problems in controlling these diseases and eliminating vectors and pests can be resolved by decision-makers and urban planners by moving away from the concept of "blanket" applications of pesticides towards integrated approaches. Sound environmental management practices and community education and participation form the mainstay of some of the most outstanding successes in this area. On the basis of these examples, it is argued that the municipal authorities need to apply a flexible methodology, which must be based on the possibilities of mobilizing community resources, with minimal reliance on routine pesticidal spraying. In this way, vector control becomes a by-product of human development in the city environment. This is now a true challenge. PMID:1568273

Knudsen, A B; Slooff, R

1992-01-01

114

Methods for control of tick vectors of Lyme Borreliosis  

USGS Publications Warehouse

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.

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

1991-01-01

115

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

PubMed Central

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

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

2013-01-01

116

Application of Lanczos vectors to control design of flexible structures  

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

117

Genetics and evolution of triatomines: from phylogeny to vector control  

PubMed Central

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

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

2012-01-01

118

Generalized Predictive Control with Online Least Squares Support Vector Machines  

Microsoft Academic Search

This paper proposes a practical generalized predictive control (GPC) algorithm based on online least squares support vector machines (LS-SVM) which can deal with nonlinear systems effectively. At each sampling period the algorithm recursively modifies the model by adding a new data pair and deleting the least important one out of the consideration on realtime property. The data pair deleted is

Li-Juan LI; Hong-Ye SU; Jian CHU

2007-01-01

119

Vector disparity sensor with vergence control for active vision systems.  

PubMed

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

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

2012-01-01

120

Voltage space vector based PWM control of forced commutated cycloconverters  

Microsoft Academic Search

A PWM (pulse-width modulation) control technique of forced commutated cycloconverters (FCCs), based on the space vector representation of the voltages in the complex plane, is considered. Output voltage and input current waveforms are analyzed in the time and frequency domains. The approach used in the analysis is valid for all practical cases of the digital implementation of the proposed FCC

L. Huber; D. Borojevic; N. Burany

1989-01-01

121

Solid rocket booster thrust vector control subsystem description  

NASA Technical Reports Server (NTRS)

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.

Redmon, J., Jr. (compiler)

1983-01-01

122

Discovering and Designing New Insecticides and their Development Vector Control.  

Technology Transfer Automated Retrieval System (TEKTRAN)

The discovery and development of novel insecticides for vector control is a primary focus of toxicology research conducted at the Mosquito and Fly Research Unit, Gainesville, FL. To identify new active ingredients, the screening of large numbers of experimental compounds is conducted using a primary...

123

Vector Disparity Sensor with Vergence Control for Active Vision Systems  

PubMed Central

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

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

2012-01-01

124

Attitude control of a spinning rocket via thrust vectoring  

SciTech Connect

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.

White, J.E.

1990-12-19

125

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

PubMed Central

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

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

2013-01-01

126

Thrust vector control algorithm design for the Cassini spacecraft  

NASA Technical Reports Server (NTRS)

This paper describes a preliminary design of the thrust vector control algorithm for the interplanetary spacecraft, Cassini. Topics of discussion include flight software architecture, modeling of sensors, actuators, and vehicle dynamics, and controller design and analysis via classical methods. Special attention is paid to potential interactions with structural flexibilities and propellant dynamics. Controller performance is evaluated in a simulation environment built around a multi-body dynamics model, which contains nonlinear models of the relevant hardware and preliminary versions of supporting attitude determination and control functions.

Enright, Paul J.

1993-01-01

127

Design of high power electromechanical actuator for thrust vector control  

NASA Technical Reports Server (NTRS)

NASA-Marshall has undertaken the development of electromechanical actuators (EMAs) for thrust vector control (TVC) augmentation system implementation. The TVC EMA presented has as its major components two three-phase brushless dc motors, a two-pass gear-reduction system, and a roller screw for rotary-to-linear motion conversion. System control is furnished by a solid-state electronic controller and power supply; a pair of resolvers deliver position feedback to the controller, such that precise positioning is achieved. Peformance comparisons have been conducted between the EMA and comparable-performance hydraulic systems applicable to TVCs.

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

1991-01-01

128

Velocity vector control system augmented with direct lift control  

NASA Technical Reports Server (NTRS)

A pilot-controlled stability control system that employs direct lift control (spoiler control) with elevator control to control the flight path angle of an aircraft is described. A computer on the aircraft generates an elevator control signal and a spoiler control signal, using a pilot-controlled pitch control signal and pitch rate, vertical velocity, roll angle, groundspeed, engine pressure ratio and vertical acceleration signals which are generated on the aircraft. The direct lift control by the aircraft spoilers improves the response of the aircraft flight path angle and provides short term flight path stabilization against environmental disturbances.

Tisdale, H. F., Sr.; Kelly, W. W. (inventors)

1981-01-01

129

Viking Orbiter 1975 thrust vector control system accuracy  

NASA Technical Reports Server (NTRS)

The thrust vector control (TVC) system of the Viking Orbiter 1975 is discussed. The purpose of the TVC system is to point the engine thrust at the vehicle center of mass and to maintain attitude stability during propulsive maneuvers. This is accomplished by mounting the engine in a two-axis gimbal system. The TVC system then controls the pointing of the engine by closed loop control of two linear actuators which extend or retract and rotate the engine in its gimbal system. The effect of the TVC on the velocity vector pointing error incurred during a propulsive maneuver is analyzed. Models for predicting the magnitude of the error for various propulsive maneuvers are developed.

Mcglinchey, L. F.

1974-01-01

130

Human African Trypanosomiasis Diagnosis in First-Line Health Services of Endemic Countries, a Systematic Review  

PubMed Central

While the incidence of Human African Trypanosomiasis (HAT) is decreasing, the control approach is shifting from active population screening by mobile teams to passive case detection in primary care centers. We conducted a systematic review of the literature between 1970 and 2011 to assess which diagnostic tools are most suitable for use in first-line health facilities in endemic countries. Our search retrieved 16 different screening and confirmation tests for HAT. The thermostable format of the Card Agglutination Test for Trypanosomiasis (CATT test) was the most appropriate screening test. Lateral flow antibody detection tests could become alternative screening tests in the near future. Confirmation of HAT diagnosis still depends on visualizing the parasite in direct microscopy. All other currently available confirmation tests are either technically too demanding and/or lack sensitivity and thus rather inappropriate for use at health center level. Novel applications of molecular tests may have potential for use at district hospital level. PMID:23209860

Mitashi, Patrick; Hasker, Epco; Lejon, Veerle; Kande, Victor; Muyembe, Jean-Jacques; Lutumba, Pascal; Boelaert, Marleen

2012-01-01

131

Attitude Control for an Aero-Vehicle Using Vector Thrusting and Variable Speed Control Moment Gyros  

NASA Technical Reports Server (NTRS)

Stabilization of passively unstable thrust-levitated vehicles can require significant control inputs. Although thrust vectoring is a straightforward choice for realizing these inputs, this may lead to difficulties discussed in the paper. This paper examines supplementing thrust vectoring with Variable-Speed Control Moment Gyroscopes (VSCMGs). The paper describes how to allocate VSCMGs and the vectored thrust mechanism for attitude stabilization in frequency domain and also shows trade-off between vectored thrust and VSCMGs. Using an H2 control synthesis methodology in LMI optimization, a feedback control law is designed for a thrust-levitated research vehicle and is simulated with the full nonlinear model. It is demonstrated that VSCMGs can reduce the use of vectored thrust variation for stabilizing the hovering platform in the presence of strong wind gusts.

Shin, Jong-Yeob; Lim, K. B.; Moerder, D. D.

2005-01-01

132

Optimal control by least squares support vector machines.  

PubMed

Support vector machines have been very successful in pattern recognition and function estimation problems. In this paper we introduce the use of least squares support vector machines (LS-SVM's) for the optimal control of nonlinear systems. Linear and neural full static state feedback controllers are considered. The problem is formulated in such a way that it incorporates the N-stage optimal control problem as well as a least squares support vector machine approach for mapping the state space into the action space. The solution is characterized by a set of nonlinear equations. An alternative formulation as a constrained nonlinear optimization problem in less unknowns is given, together with a method for imposing local stability in the LS-SVM control scheme. The results are discussed for support vector machines with radial basis function kernel. Advantages of LS-SVM control are that no number of hidden units has to be determined for the controller and that no centers have to be specified for the Gaussian kernels when applying Mercer's condition. The curse of dimensionality is avoided in comparison with defining a regular grid for the centers in classical radial basis function networks. This is at the expense of taking the trajectory of state variables as additional unknowns in the optimization problem, while classical neural network approaches typically lead to parametric optimization problems. In the SVM methodology the number of unknowns equals the number of training data, while in the primal space the number of unknowns can be infinite dimensional. The method is illustrated both on stabilization and tracking problems including examples on swinging up an inverted pendulum with local stabilization at the endpoint and a tracking problem for a ball and beam system. PMID:11213211

Suykens, J A; Vandewalle, J; De Moor, B

2001-01-01

133

CFD evaluation of an advanced thrust vector control concept  

NASA Technical Reports Server (NTRS)

A potential concept that can offer an alternate method for thrust vector control of the Space Shuttle Solid Rocket Booster is the use of a cylindrical probe that is inserted (on demand) through the wall of the rocket nozzle. This Probe Thrust Vector Control (PTVC) concept is an alternate to that of a gimbaled nozzle or a Liquid Injection Thrust Vector (LITVC) system. The viability of the PTVC concept can be assessed either experimentally and/or with the use of CFD. A purely experimental assessment can be time consuming and expensive, whereas a CFD assessment can be very time- and cost-effective. Two key requirements of the proposed concept are PTVC vectoring performance and the active cooling requirements for the probe to maintain its thermal and structural integrity. An active thermal cooling method is the injection of coolant around the pheriphery of the probe. How much coolant is required and how this coolant distributes itself in the flow field is of major concern. The objective of the work reported here is the use of CFD to answer these question and in the design of test hardware to substantiate the results of the CFD predictions.

Tiarn, Weihnurng; Cavalleri, Robert

1990-01-01

134

Research on two space vector current control strategies for three phase voltage source PWM rectifier  

Microsoft Academic Search

In this paper, to improve the control speed of three phase PWM VSI's ac-side current, two space vector current control strategies are proposed respectively named current- space-vector hysteresis control based on projection method and optimized current-space-vector control. The current- space-vector hysteresis control based on projection method is to find a switch state in real time based on the electric variables

Zhang Xiang; Ma Kun; Li Ning

2011-01-01

135

Fault tolerant vector control of induction motor drive  

NASA Astrophysics Data System (ADS)

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.

Odnokopylov, G.; Bragin, A.

2014-10-01

136

Direct torque control, induction motor vector control without an encoder  

Microsoft Academic Search

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

James N. Nash

1997-01-01

137

Design and test of electromechanical actuators for thrust vector control  

NASA Technical Reports Server (NTRS)

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 vehicle. In light of this continued concern to improve the TVC system, the Propulsion Laboratory at the NASA George C. Marshall Space Flight Center (MSFC) is involved in a program to develop electromechanical actuators for the purpose of testing and TVC system implementation. Through this effort, an electromechanical thrust vector control actuator has been designed and assembled. The design consists of the following major components: Two three-phase brushless dc motors, a two pass gear reduction system, and a roller screw, which converts rotational input into linear output. System control is provided by a solid-state electronic controller and power supply. A pair of resolvers and associated electronics deliver position feedback to the controller such that precise positioning is achieved. Testing and evaluation is currently in progress. Goals focus on performance comparisons between EMA's and similar hydraulic systems.

Cowan, J. R.; Weir, Rae Ann

1993-01-01

138

Costs Of Using “Tiny Targets” to Control Glossina fuscipes fuscipes, a Vector of Gambiense Sleeping Sickness in Arua District of Uganda  

PubMed Central

Introduction To evaluate the relative effectiveness of tsetse control methods, their costs need to be analysed alongside their impact on tsetse populations. Very little has been published on the costs of methods specifically targeting human African trypanosomiasis Methodology/Principal Findings In northern Uganda, a 250 km2 field trial was undertaken using small (0.5 X 0.25 m) insecticide-treated targets (“tiny targets”). Detailed cost recording accompanied every phase of the work. Costs were calculated for this operation as if managed by the Ugandan vector control services: removing purely research components of the work and applying local salaries. This calculation assumed that all resources are fully used, with no spare capacity. The full cost of the operation was assessed at USD 85.4 per km2, of which USD 55.7 or 65.2% were field costs, made up of three component activities (target deployment: 34.5%, trap monitoring: 10.6% and target maintenance: 20.1%). The remaining USD 29.7 or 34.8% of the costs were for preliminary studies and administration (tsetse surveys: 6.0%, sensitisation of local populations: 18.6% and office support: 10.2%). Targets accounted for only 12.9% of the total cost, other important cost components were labour (24.1%) and transport (34.6%). Discussion Comparison with the updated cost of historical HAT vector control projects and recent estimates indicates that this work represents a major reduction in cost levels. This is attributed not just to the low unit cost of tiny targets but also to the organisation of delivery, using local labour with bicycles or motorcycles. Sensitivity analyses were undertaken, investigating key prices and assumptions. It is believed that these costs are generalizable to other HAT foci, although in more remote areas, with denser vegetation and fewer people, costs would increase, as would be the case for other tsetse control techniques. PMID:25811956

Shaw, Alexandra P. M.; Tirados, Inaki; Mangwiro, Clement T. N.; Esterhuizen, Johan; Lehane, Michael J.; Torr, Stephen J.; Kovacic, Vanja

2015-01-01

139

American Trypanosomiasis (Also Known as Chagas Disease) Treatment  

MedlinePLUS

... About CDC.gov . Parasites - American Trypanosomiasis (also known as Chagas Disease) Parasites Home Share Compartir Treatment Treatment ... patients may be referred to a specialist, such as a cardiologist, gastroenterologist, or infectious disease specialist. In ...

140

American Trypanosomiasis (Also Known as Chagas Disease) Diagnosis  

MedlinePLUS

... About CDC.gov . Parasites - American Trypanosomiasis (also known as Chagas Disease) Parasites Home Share Compartir Diagnosis Trypansoma ... made after consideration of the patient's clinical findings, as well as by the likelihood of being infected, ...

141

Inverter nonlinearities and discrete-time vector current control  

Microsoft Academic Search

This paper studies all-digital discrete-time vector current control loops containing a voltage fed invertor in series with a permanent-magnet synchronous motor. Normal operation of the typical pulse width modulating voltage fed inverter introduces nonlinear distortion into the voltage and the current waveforms of the motor. This paper focuses on both the causes and the attenuation of these disturbances using all-digital

Raymond B. Sepe; Jeffrey H. Lang

1994-01-01

142

A research agenda for malaria eradication: vector control.  

PubMed

Different challenges are presented by the variety of malaria transmission environments present in the world today. In each setting, improved control for reduction of morbidity is a necessary first step towards the long-range goal of malaria eradication and a priority for regions where the disease burden is high. For many geographic areas where transmission rates are low to moderate, sustained and well-managed application of currently available tools may be sufficient to achieve local elimination. The research needs for these areas will be to sustain and perhaps improve the effectiveness of currently available tools. For other low-to-moderate transmission regions, notably areas where the vectors exhibit behaviours such as outdoor feeding and resting that are not well targeted by current strategies, new interventions that target predictable features of the biology/ecologies of the local vectors will be required. To achieve elimination in areas where high levels of transmission are sustained by very efficient vector species, radically new interventions that significantly reduce the vectorial capacity of wild populations will be needed. Ideally, such interventions should be implemented with a one-time application with a long-lasting impact, such as genetic modification of the vectorial capacity of the wild vector population. PMID:21311587

2011-01-01

143

Human African trypanosomiasis: quantitative and qualitative assessment of intrathecal immune response.  

PubMed

Quantitative and qualitative techniques for assessment of the intrathecal humoral immune response in human African trypanosomiasis were compared, and their diagnostic potential for detection of the meningo-encephalitic stage of the disease was evaluated. Total and trypanosome specific immunoglobulin G (IgG) and IgM intrathecal synthesis were studied in paired cerebrospinal fluid (CSF) and blood samples of 38 trypanosomiasis patients and in three controls using Reiber's formulae. The presence of CSF-specific oligoclonal IgG and of trypanosome-specific antibodies was determined using iso-electric focusing followed by immunoblotting and antigen-driven immunoblots. The intrathecal IgG fraction (16% positive) and oligoclonal IgG detection (24% positive) were insensitive for detection of an intrathecal humoral immune response. Trypanosome-specific IgG synthesis, reflected by the IgG antibody index (AI) (26% positive), was confirmed by the presence of oligoclonal specific IgG (47% positive), but the latter was more sensitive. Although the detection technique failed for oligoclonal IgM, the intrathecal IgM fraction (42% positive) and the IgM AI (32% positive) indicated that the meningo-encephalitic stage of the disease is characterized by a dominant intrathecal IgM response, which was higher than the IgG response. The highest combination of diagnostic sensitivity and specificity for the meningo-encephalitic stage of trypanosomiasis was observed for quantitative IgM determinations. PMID:14641518

Lejon, V; Sindic, C J M; Van Antwerpen, M-P; Doua, F; Djé, N; Solano, P; Jamonneau, V; Wouters, I; Büscher, P

2003-11-01

144

Research on the sliding-mode variable structure control based on the vector control of PMSM  

Microsoft Academic Search

Based on the vector control system of permanent magnet synchronous motor (PMSM), an integral Variable Structure Control (VSC) is designed in this paper through the application of variable structure control theory with sliding- mode. Furthermore, by means of Matlab \\/ Simulink, a simulation analysis on the control structure is performed to examine the effects of different parameters on the system

Xu Dan; Huanqiang Luo; Wang Feng; Xiaomei Yin; Nianxing Fang

2011-01-01

145

Decoupling control of thrust and attractive force of a LIM using a space vector control inverter  

Microsoft Academic Search

A control method for magnetic levitation vehicles using linear induction motors which can generate both thrust and attractive force, is described. By selecting voltage vectors of PWM inverters appropriately, control with decoupling of the thrust and attractive force is achieved. Levitation control is accomplished by detecting the gap length and controlling the attractive force of each linear induction motor. Ultrasonic

Isao Takahashi; Yuji Ide

1993-01-01

146

Vectors  

NSDL National Science Digital Library

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.

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

147

IEEE Transactions on Evolutionary Computation 1 Abstract--Trial vector generation strategies and control  

E-print Network

control parameter settings. It randomly combines them to generate trial vectors. CoDE has been tested three well-studied trial vector generation strategies with three control parameter settings in a random Terms--Differential evolution, trial vector generation strategy, control parameters, global numerical

Zhang, Qingfu

148

Underpinning Sustainable Vector Control through Informed Insecticide Resistance Management  

PubMed Central

Background There has been rapid scale-up of malaria vector control in the last ten years. Both of the primary control strategies, long-lasting pyrethroid treated nets and indoor residual spraying, rely on the use of a limited number of insecticides. Insecticide resistance, as measured by bioassay, has rapidly increased in prevalence and has come to the forefront as an issue that needs to be addressed to maintain the sustainability of malaria control and the drive to elimination. Zambia's programme reported high levels of resistance to the insecticides it used in 2010, and, as a result, increased its investment in resistance monitoring to support informed resistance management decisions. Methodology/Principal Findings A country-wide survey on insecticide resistance in Zambian malaria vectors was performed using WHO bioassays to detect resistant phenotypes. Molecular techniques were used to detect target-site mutations and microarray to detect metabolic resistance mechanisms. Anopheles gambiae s.s. was resistant to pyrethroids, DDT and carbamates, with potential organophosphate resistance in one population. The resistant phenotypes were conferred by both target-site and metabolic mechanisms. Anopheles funestus s.s. was largely resistant to pyrethroids and carbamates, with potential resistance to DDT in two locations. The resistant phenotypes were conferred by elevated levels of cytochrome p450s. Conclusions/Significance Currently, the Zambia National Malaria Control Centre is using these results to inform their vector control strategy. The methods employed here can serve as a template to all malaria-endemic countries striving to create a sustainable insecticide resistance management plan. PMID:24932861

Hemmings, Kay; Hughes, Angela J.; Chanda, Emmanuel; Musapa, Mulenga; Kamuliwo, Mulakwa; Phiri, Faustina N.; Muzia, Lucy; Chanda, Javan; Kandyata, Alister; Chirwa, Brian; Poer, Kathleen; Hemingway, Janet; Wondji, Charles S.; Ranson, Hilary; Coleman, Michael

2014-01-01

149

Vector inversion diminishes the online control of antisaccades.  

PubMed

Antisaccades require the suppression of a stimulus-driven response (i.e., response suppression) and the computation of a movement plan mirror-symmetrical to the location of a target (i.e., vector inversion). The goal of the present study was to determine whether response suppression, vector inversion or both contribute to previously reported differences in the online control of pro- and antisaccades (Heath in Exp Brain Res 203:743-752, 2010a). Pro- and antisaccades were completed in separate blocks (i.e., blocked schedule) and a block wherein the spatial relation between stimulus and response was provided at response cuing (i.e., random schedule). Notably, the random schedule provides a relative means for equating response suppression across pro- and antisaccades. To examine online trajectory amendments, we computed the proportion of variance (R² values) explained by the spatial location of the eye at early, middle and late stages of saccade trajectories relative to the saccade's ultimate endpoint. The basis for this analysis is that between-task differences in R² magnitudes reflect differences in the use of feedback for online trajectory amendments: small R² values represent a trajectory supported via online control whereas larger R² values reflect a reduction in online control. Results show that antisaccades yielded larger R² values than prosaccades from early to late stages of saccade trajectories, and this finding was observed regardless of whether or not tasks were equated for response suppression. Thus, we propose that the intentional nature of vector inversion disrupts the normally online control of saccades and renders a mode of control that is not optimized to support error-reducing trajectory amendments. PMID:21210087

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

2011-03-01

150

Harnessing mosquito-Wolbachia symbiosis for vector and disease control.  

PubMed

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

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

151

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

E-print Network

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...

Anderson, Neil Euan

2009-01-01

152

Shading curves: vector-based drawing with explicit gradient control  

E-print Network

colours with shading profiles. In the following, we present ways in which the final stage can be performed efficiently. Figure 12(a–b) shows cartoon-like images created using the default settings ((?i,2,?i,2) = (0.15,1.0);(?i,3,?i,3) = (0.4,0.0);hi =±20;ei... , 1978. 2, 4 [DKT98] DEROSE T., KASS M., TRUONG T.: Subdivision surfaces in character animation. In Proc. SIGGRAPH (1998), vol. 25, ACM, pp. 85–94. 7 [FSH11] FINCH M., SNYDER J., HOPPE H.: Freeform vector graphics with controlled thin-plate splines. ACM...

Lieng, Henrik; Tasse, Flora; Kosinka, Ji?í; Dodgson, Neil A.

2015-01-01

153

Mixture for Controlling Insecticide-Resistant Malaria Vectors  

PubMed Central

The spread of resistance to pyrethroids in the major Afrotropical malaria vectors Anopheles gambiae s.s. necessitates the development of new strategies to control resistant mosquito populations. To test the efficacy of nets treated with repellent and insecticide against susceptible and insecticide-resistant An. gambiae mosquito populations, we impregnated mosquito bed nets with an insect repellent mixed with a low dose of organophosphorous insecticide and tested them in a rice-growing area near Bobo-Dioulasso, Burkina Faso. During the first 2 weeks posttreatment, the mixture was as effective as deltamethrin alone and was more effective at killing An. gambiae that carried knockdown resistance (kdr) or insensitive acetylcholinesterase resistance (Ace1R) genes. The mixture seemed to not kill more susceptible genotypes for the kdr or Ace1R alleles. Mixing repellents and organophosphates on bed nets could be used to control insecticide-resistant malaria vectors if residual activity of the mixture is extended and safety is verified. PMID:18976553

Costantini, Carlo; Corbel, Vincent; Licciardi, Séverine; Dabiré, Roch K.; Lapied, Bruno; Chandre, Fabrice; Hougard, Jean-Marc

2008-01-01

154

Human trypanosomiasis in the Ivory Coast: therapy and problems.  

PubMed

Human African trypanosomiasis (sleeping sickness) caused by Trypanosoma gambiense is recrudescing alarmingly in the Ivory Coast. Between 1987 and 1992, 980 new cases were registered. In the Bouafle District alone, 214 new cases were diagnosed in 1992, with a prevalence reaching 7% in some villages. This situation is a consequence of the neglect of control activities over the last five years. The problems linked with treatment of sleeping sickness in 626 patients, using three drugs, are described. The side-effects vary in severity according to the drug used. Out of 350 patients treated with melarsoprol (ARSOBAL), 4% developed encephalopathy, 5.7% died during treatment, 2% of encephalopathy. Relapses were noted in 3.7% of patients between 3 and 20 months after treatment. Among 150 patients treated with pentamidine, one case of diabetes mellitus was observed. The patient died of this complication 24 months after treatment. 2% relapses or reinfections were registered after pentamidine treatment. The most frequently encountered side-effects during intravenous plus oral treatment with DFMO were diarrhoea (64.4%) and anemia (35.5%). This drug was just as effective and better tolerated when treatment was limited to 14 days and administered intravenously only. PMID:7902655

Doua, F; Yapo, F B

1993-09-01

155

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

Microsoft Academic Search

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

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

1997-01-01

156

Challenges and future perspective for dengue vector control in the Western Pacific Region  

PubMed Central

Dengue remains a significant public health issue in the Western Pacific Region. In the absence of a vaccine, vector control is the mainstay for dengue prevention and control. In this paper we describe vector surveillance and vector control in the Western Pacific countries and areas. Vector surveillance and control strategies used by countries and areas of the Western Pacific Region vary. Vector control strategies include chemical, biological and environmental management that mainly target larval breeding sites. The use of insecticides targeting larvae and adult mosquitoes remains the mainstay of vector control programmes. Existing vector control tools have several limitations in terms of cost, delivery and long-term sustainability. However, there are several new innovative tools in the pipeline. These include Release of Insects Carrying a Dominant Lethal system and Wolbachia, an endosymbiotic bacterium, to inhibit dengue virus in the vector. In addition, the use of biological control such as larvivorous fish in combination with community participation has potential to be scaled up. Any vector control strategy should be selected based on evidence and appropriateness for the entomological and epidemiological setting and carried out in both inter-epidemic and epidemic periods. Community participation and interagency collaboration are required for effective and sustainable dengue prevention and control. Countries and areas are now moving towards integrated vector management. PMID:23908883

Christophel, Eva Maria; Gopinath, Deyer; Abdur, Rashid Md.; Vectorborne, Other; Diseases, Parasitic

2011-01-01

157

Community involvement in dengue vector control: cluster randomised trial  

PubMed Central

Objective To assess the effectiveness of an integrated community based environmental management strategy to control Aedes aegypti, the vector of dengue, compared with a routine strategy. Design Cluster randomised trial. Setting Guantanamo, Cuba. Participants 32 circumscriptions (around 2000 inhabitants each). Interventions The circumscriptions were randomly allocated to control clusters (n=16) comprising routine Aedes control programme (entomological surveillance, source reduction, selective adulticiding, and health education) and to intervention clusters (n=16) comprising the routine Aedes control programme combined with a community based environmental management approach. Main outcome measures The primary outcome was levels of Aedes infestation: house index (number of houses positive for at least one container with immature stages of Ae aegypti per 100 inspected houses), Breteau index (number of containers positive for immature stages of Ae aegypti per 100 inspected houses), and the pupae per inhabitant statistic (number of Ae aegypti pupae per inhabitant). Results All clusters were subjected to the intended intervention; all completed the study protocol up to February 2006 and all were included in the analysis. At baseline the Aedes infestation levels were comparable between intervention and control clusters: house index 0.25% v 0.20%, pupae per inhabitant 0.44×10?3 v 0.29×10?3. At the end of the intervention these indices were significantly lower in the intervention clusters: rate ratio for house indices 0.49 (95% confidence interval 0.27 to 0.88) and rate ratio for pupae per inhabitant 0.27 (0.09 to 0.76). Conclusion A community based environmental management embedded in a routine control programme was effective at reducing levels of Aedes infestation. Trial registration Current Controlled Trials ISRCTN88405796. PMID:19509031

2009-01-01

158

Trapping volume control in optical tweezers using cylindrical vector beams.  

PubMed

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

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

2013-01-01

159

Space Transportation System solid rocket booster thrust vector control system  

NASA Technical Reports Server (NTRS)

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.

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

1980-01-01

160

Space transportation system solid rocket booster thrust vector control system  

NASA Technical Reports Server (NTRS)

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.

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

1979-01-01

161

African trypanosome control in the insect vector and mammalian host.  

PubMed

The life cycle of African trypanosomes involves adaptations to the defense mechanisms of two completely different hosts, the insect vector Glossina and the mammalian host. This interplay ultimately determines host resistance and/or tolerance to parasite infection. In the tsetse fly, the immune deficiency (IMD)-regulated pathway, the scavenger receptor peptidoglycan-recognition protein LB (PGRP-LB), and the reactive oxygen species (ROS)-mediated response modulate the insect's capacity to transmit the parasite. In experimental mice, control of parasite burden and tissue pathogenicity relies on timely regulated interactions between myeloid cells exhibiting distinct activation states (M1 versus M2 type). Tsetse fly saliva and various trypanosome components including adenylate cyclases, DNA, a kinesin heavy chain, and variant surface glycoprotein (VSG) interfere with resistance and tolerance to infection. PMID:25246021

Beschin, Alain; Van Den Abbeele, Jan; De Baetselier, Patrick; Pays, Etienne

2014-11-01

162

A general space vector PWM control algorithm for multilevel inverters  

Microsoft Academic Search

To solve the problem of computational complexity in multilevel inverters due to the large number of space vectors and redundant switching states, a simple and general space vector PWM algorithm is proposed. Based on this algorithm, the location of the reference voltage vector can be easily determined and the calculation of dwell times becomes very simple. More importantly, the proposed

Sanmin Wei; Bin Wu; Fahai Li; Congwei Liu

2003-01-01

163

Space vector PWM control of dual inverter fed open-end winding induction motor drive  

Microsoft Academic Search

A space vector PWM technique is developed based on the combination of space vectors from dual inverters feeding the induction motor from both ends (open-end winding without neutral point). A total of 64 voltage space vector combinations are available for PWM voltage control of the inverter fed machine with open-end winding. A space phasor based PWM scheme is proposed with

E. G. Shivakumar; K. Gopakumar; S. K. Sinha; Andrei Pittet; V. T. Ranganathan

2001-01-01

164

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

E-print Network

-economical effects throughout Central and South America. Vector control programs have consistently reduced domestic of the village, where vectors were most abundant. Indoor insecticide spraying and insect screens reduced vector abundance by up to 80% (when applied to the whole village), and half of this effect was obtained when

Paris-Sud XI, Université de

165

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

E-print Network

instances, however, insecticide resis- tance may have the opposite effect, increasing the insect's vectorialReview Insecticide Control of Vector-Borne Diseases: When Is Insecticide Resistance a Problem? Ana diseases are transmitted by insect vectors. After decades of repeated insecticide use, all of these vector

Rivero, Ana

166

A vector control system using a neutral-point-clamped voltage source PWM inverter  

Microsoft Academic Search

A description is presented of a vector control system of an induction machine using a neutral point clamped voltage source inverter (NPC-VSI) that is one of double series connected inverters. This system is characterized by the NPC-VSI and a sophisticated current controller based on the space vector theory. The current controller proposed in is capable of reducing harmonic currents to

Satoshi Ogasawara; K. Akagi

1991-01-01

167

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

Microsoft Academic Search

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

L. Xu; J. Yao

1992-01-01

168

[Risk factors for human African trypanosomiasis in the endemic foci of Ivory Coast].  

PubMed

A case-control study on risk factors of Trypanosoma brucei gambiense human african trypanosomiasis was carried out in 111 patients diagnosed in the three main foci of Ivory coast. Each case was age and sex matched with one seronegative control living in the same locality. Based upon previous epidemiological surveys conducted in similar areas, the potential risk factors were identified and assessed using a standard questionnaire. The study demonstrates that in the forest area of Ivory coast human trypanosomiasis in a behavioral disease affecting mainly coffee and cocoa farmers. The allogenous populations coming from sudano-sahelian savannah are more exposed to the disease than other ethnic groups. People sleeping at the farm (encampments) are more likely to become infected than those living at the village (ODDS-Ratio = 4.5). People fetching water in natural holes and pools have an increased risk (ODDS-Ratio = 3.6). Cases reported more often than controls that they are foodstuffs dealers from the farms to the villages (ODDS-Ratio = 13.0). These results are consistent with data from previous studies. We identified preventable risk factors, upon which interventions should be carried out to reduce the incidence of the disease. The possibility of using these findings to improve sleeping sickness control programme in the forest areas of Ivory Coast is discussed. PMID:8389414

Meda, A H; Laveissiere, C; De Muynck, A; Doua, F; Diallo, P B

1993-01-01

169

Performances of fuzzy-logic-based indirect vector control for induction motor drive  

Microsoft Academic Search

This paper presents a novel speed control scheme of an induction motor (IM) using fuzzy-logic control. The fuzzy-logic controller (FLC) is based on the indirect vector control. The fuzzy-logic speed controller is employed in the outer loop. The complete vector control scheme of the IM drive incorporating the FLC is experimentally implemented using a digital signal processor board DS-1102 for

M. Nasir Uddin; Tawfik S. Radwan; M. Azizur Rahman

2002-01-01

170

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

Microsoft Academic Search

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

Junyi Shen; Wenguang Luo; Chengwu Yang; Deliang Meng

2011-01-01

171

African trypanosomiasis: Sensitive and rapid detection of the sub-genus Trypanozoon by loop-mediated isothermal amplification (LAMP) of parasite DNA  

Microsoft Academic Search

Control of human African trypanosomiasis (HAT) is dependent on accurate diagnosis and treatment of infected patients. However, sen- sitivities of tests in routine use are unsatisfactory, due to the characteristically low parasitaemias in naturally infected individuals. We have identified a conserved sequence in the repetitive insertion mobile element (RIME) of the sub-genus Trypanozoon and used it to design prim- ers

Z. K. Njiru; A. S. J. Mikosza; E. Matovu; J. C. K. Enyaru; J. O. Ouma; S. N. Kibona; R. C. A. Thompson

2007-01-01

172

Plasmid vector with temperature-controlled gene expression  

SciTech Connect

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

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

1986-02-01

173

ProactiveVector control strategies and improved monitoring and evaluation practices for dengue prevention.  

PubMed

Despite tremendous efforts by public health organizations in dengue-endemic countries, it has proven difficult to achieve effective and sustainable control of the primary dengue virus vector Aedes aegypti (L.) and to effectively disrupt dengue outbreaks. This problem has multiple root causes, including uncontrolled urbanization, increased global spread of dengue viruses, and vector and dengue control programs not being provided adequate resources. In this forum article, we give an overview of the basic elements of a vector and dengue control program and describe a continuous improvement cyclical model to systematically and incrementally improve control program performance by regular efforts to identify ineffective methods and inferior technology, and then replacing them with better performing alternatives. The first step includes assessments of the overall resource allocation among vector/dengue control program activities, the efficacy of currently used vector control methods, and the appropriateness of technology used to support the program. We expect this will reveal that 1) some currently used vector control methods are not effective, 2) resource allocations often are skewed toward reactive vector control measures, and 3) proactive approaches commonly are underfunded and therefore poorly executed. Next steps are to conceptualize desired changes to vector control methods or technologies used and then to operationally determine in pilot studies whether these changes are likely to improve control program performance. This should be followed by a shift in resource allocation to replace ineffective methods and inferior technology with more effective and operationally tested alternatives. The cyclical and self-improving nature of the continuous improvement model will produce locally appropriate management strategies that continually are adapted to counter changes in vector population or dengue virus transmission dynamics. We discuss promising proactive vector control approaches and the continued need for the vector and dengue control community to incorporate emerging technologies and to partner with academia, business and the community-at-large to identify new solutions that reduce dengue. PMID:19960667

Eisen, Lars; Beaty, Barry J; Morrison, Amy C; Scott, Thomas W

2009-11-01

174

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

PubMed Central

Comprehensive georeference records for human African trypanosomiasis in Cameroon, Central African Republic, Chad, Congo, Equatorial Guinea, and Gabon were combined with human population layers to estimate a kernel-smoothed relative risk function. Five risk categories were mapped, and ?3.5 million persons were estimated to be at risk for this disease. PMID:22172322

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

2011-01-01

175

MODEL PREDICTIVE CONTROL OF A THRUST-VECTORED FLIGHT CONTROL EXPERIMENT  

Microsoft Academic Search

Model predictive control (MPC) is applied to the Caltech ducted fan, a thrust-vectored ?ight experiment. A real-time trajectory generation software based on spline theory and sequential quadratic programming is used to implement the MPC controllers. Timing issues related to the computation and implementation of repeatedly updated optimal trajectories are discussed. Results show computational speeds greater than 10 Hz, 2.5 times

William B. Dunbar; Mark B. Milam; Ryan Franz; Richard M. Murray

2002-01-01

176

Novel vector control system using deadbeat-controlled PWM inverter with output LC filter  

Microsoft Academic Search

This paper proposes a novel high-performance vector control system of an ac motor using a low-switching-frequency (2 kHz) pulsewidth-modulation voltage-source inverter with an output LC filter. Excellent high-speed response characteristics of the LC filter output voltage have been realized using a novel deadbeat control algorithm. As for the experimental results, the torque current response that is similar to the response

Mari Kojima; Kazufumi Hirabayashi; Yoshitaka Kawabata; Emenike C. Ejiogu; Takao Kawabata

2004-01-01

177

[Prevention and control of leishmaniasis vectors: current approaches].  

PubMed

Phlebotomine sandflies (Diptera: Psychodidae) are the suspected or proven vectors of Leishmania spp. in at least 88 countries, including over 40 Phlebotomus species in the Old World and a further 30 belonging to the genus Lutzomyia in the New World. In recent years, both cutaneous (CL) and zoonotic visceral leishmaniasis (ZVL) have become increasingly prevalent in urban areas, including large Latin American cities. A similar trend has been recorded in all Mediterranean areas during the last decade. Based on mathematical models, insecticidal control of sandflies appears to represent a more effective way of reducing Leishmania infantum transmission than the present strategy of culling infected dogs in Latin America as well as being more acceptable to the human population. Since man is a dead-end host of most Leishmania species, treatment of existing human cases generally does not affect transmission. Interruption of the cycle by vector control may offer a cheaper, more practical solution to treatment and improved knowledge of the alternatives available could lead to preventative measures being undertaken in more leishmaniasis foci. In this note a review of current knowledge on sandfly control is presented. Different measures to control phlebotomine sandflies, including residual spraying of dwellings and animal shelters, insecticide treated nets, application of repellents/insecticides to skin or to fabrics and impregnated dog collars are discussed. Although effective in urban areas with high concentrations of sandflies, residual spraying of insecticides is no often longer tenable in most situations. In rural areas where dwellings are more dispersed and surrounded by large, untargeted "reservoir" populations of sandflies, residual spraying of houses may be both impractical for logistic reasons and ineffective. Actually, this control measure depends on the availability of a suitable public health infrastructure, including adequate supplies of insecticide, spraying equipment and trained personnel. Ideally such personnel should be trained in insecticide application, monitoring techniques and interpretation of sampling data, as well as safety techniques. To date reports of resistance refer to one insecticide (DDT) in only three species (Phlebotomus papatasi, P. argentipes and Sergentomyia shorti) in one country (India), although there are reports of increased tolerance to this compound in several countries. Fortunately the insects remain susceptible to all the major insecticidal groups. Impregnated bednets may offer the best solution in rural areas where transmission is largely intradomiciliary. This measure has the advantage that it can be employed at the individual household level and affords collateral benefits such as privacy and control of other biting insects such as mosquitoes, fleas and bedbugs. Sandfly larvae are generally difficult to find in nature so control measures that act specifically against immatures are not feasible, although the effectiveness of a few biological and chemical agents has been demonstrated in laboratory evaluations. In ZVL foci, where dogs are the unique domestic reservoir, a reduction in Leishmania transmission would be expected if we could combine an effective mass treatment of infected dogs with a protection of both healthy and infected dogs from the sandfly bites. Laboratory and field evaluations have shown that impregnated dog collars and topical application of insecticides could protect dogs from most sandfly bites by means of both anti-feeding and killing effect of the pirethorids used. PMID:15305719

Maroli, M; Khoury, C

2004-06-01

178

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

USGS Publications Warehouse

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

Ginsberg, H.S.

2001-01-01

179

Trypanosoma cruzi: adaptation to its vectors and its hosts  

PubMed Central

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

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

2009-01-01

180

Cost-effectiveness of algorithms for confirmation test of human African trypanosomiasis.  

PubMed

The control of Trypanosoma brucei gambiense human African trypanosomiasis (HAT) is compromised by low sensitivity of the routinely used parasitologic confirmation tests. More sensitive alternatives, such as mini-anion exchange centrifugation technique (mAECT) or capillary tube centrifugation (CTC), are more expensive. We used formal decision analysis to assess the cost-effectiveness of alternative HAT confirmation algorithms in terms of cost per life saved. The effectiveness of the standard method, a combination of lymph node puncture (LNP), fresh blood examination (FBE), and thick blood film (TBF), was 36.8%; the LNP-FBE-CTC-mAECT sequence reached almost 80%. The cost per person examined ranged from euro1.56 for LNP-FBE-TBF to euro2.99 for LNP-TBF-CTC-mAECT-CATT (card agglutination test for trypanosomiasis) titration. LNP-TBF-CTC-mAECT was the most cost-effective in terms of cost per life saved. HAT confirmation algorithms that incorporate concentration techniques are more effective and efficient than the algorithms that are currently and routinely used by several T.b. gambiense control programs. PMID:18257991

Lutumba, Pascal; Meheus, Filip; Robays, Jo; Miaka, Constantin; Kande, Victor; Büscher, Philippe; Dujardin, Bruno; Boelaert, Marleen

2007-10-01

181

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....

182

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

Microsoft Academic Search

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

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

1999-01-01

183

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

Microsoft Academic Search

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

D. Hadiouche; H. Razik; A. Rezzoug

2000-01-01

184

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

Microsoft Academic Search

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

Fang-Zheng Peng; Tadashi Fukao

1994-01-01

185

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

Microsoft Academic Search

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

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

2006-01-01

186

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...

187

Comparative Field Trial of Alternative Vector Control Strategies for Non-Domiciliated Triatoma dimidiata  

PubMed Central

Chagas disease is a major vector-borne disease, and regional initiatives based on insecticide spraying have successfully controlled domiciliated vectors in many regions. Non-domiciliated vectors remain responsible for a significant transmission risk, and their control is a challenge. We performed a proof-of-concept field trial to test alternative strategies in rural Yucatan, Mexico. Follow-up of house infestation for two seasons following the interventions confirmed that insecticide spraying should be performed annually for the effective control of Triatoma dimidiata; however, it also confirmed that insect screens or long-lasting impregnated curtains may represent good alternative strategies for the sustained control of these vectors. Ecosystemic peridomicile management would be an excellent complementary strategy to improve the cost-effectiveness of interventions. Because these strategies would also be effective against other vector-borne diseases, such as malaria or dengue, they could be integrated within a multi-disease control program. PMID:20064997

Ferral, Jhibran; Chavez-Nuñez, Leysi; Euan-Garcia, Maria; Ramirez-Sierra, Maria Jesus; Najera-Vazquez, M. Rosario; Dumonteil, Eric

2010-01-01

188

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

PubMed

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

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

2014-01-01

189

High-Speed Current dq PI Controller for Vector Controlled PMSM Drive  

PubMed Central

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

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

2014-01-01

190

Control of multiple arthropod vector infestations with subolesin/akirin vaccines.  

PubMed

Diseases transmitted by arthropod vectors such as mosquitoes, ticks and sand flies greatly impact human and animal health and thus their control is important for the eradication of vector-borne diseases (VBD). Vaccination is an environmentally friendly alternative for vector control that allows control of several VBD by targeting their common vector. Recent results have suggested that subolesin/akirin (SUB/AKR) is good candidate antigens for the control of arthropod vector infestations. Here we describe the comparative effect of vaccination with SUB, AKR and Q38 and Q41 chimeras containing SUB/AKR conserved protective epitopes on tick, mosquitoes and sand flies vector mortality, molting, oviposition and/or fertility. We demonstrated that SUB vaccination had the highest efficacy (E) across all vector species (54-92%), Q41 vaccination had the highest vaccine E in mosquitoes (99%) by reducing female survival and fertility, and Q38 vaccination had the highest effect on reducing mosquito (28%) and sand fly (26%) oviposition. The effect of vaccination on different developmental processes in several important arthropod vectors encourages the development of SUB/AKR universal vaccines for the control of multiple vector infestations and reduction of VBD. PMID:23291476

Moreno-Cid, Juan A; Pérez de la Lastra, José M; Villar, Margarita; Jiménez, Maribel; Pinal, Rocío; Estrada-Peña, Agustín; Molina, Ricardo; Lucientes, Javier; Gortázar, Christian; de la Fuente, José

2013-02-01

191

A novel vector control scheme for transistor PWM inverter-fed induction motor drive  

Microsoft Academic Search

A novel vector control scheme for a transistor pulse-width-modulation (PWM)-inverter-fed induction motor drive is presented. The system is based on a current control loop that consists of two independent nonlinear controllers that regulate the DC (field-oriented) components of the stator current vector. Three-level hysteresis comparators are used as current controllers. The outputs of the comparators select the appropriate inverter output

Marian P. Kazmierkowski; Waldemar Sulkowski

1991-01-01

192

An improved voltage vector control method for neutral-point-clamped inverters  

Microsoft Academic Search

A new PWM method for neutral-point-clamped (NPC) inverters is introduced. The method is based on closed-loop control of the line-to-line voltage vectors. It uses independent hysteresis comparator controllers to regulate the direct and quadrature axis components of the three phase output voltages. The controllers select the appropriate output voltage-vector through an EPROM table. The closed-loop control allows a high performance

Roberto Rojas; Tokuo Ohnishi; Takayuki Suzuki

1995-01-01

193

A Review of Ecological Factors Associated with the Epidemiology of Wildlife Trypanosomiasis in the Luangwa and Zambezi Valley Ecosystems of Zambia  

PubMed Central

Trypanosomiasis has been endemic in wildlife in Zambia for more than a century. The disease has been associated with neurological disorders in humans. Current conservation strategies by the Zambian government of turning all game reserves into state-protected National Parks (NPs) and game management areas (GMAs) have led to the expansion of the wildlife and tsetse population in the Luangwa and Zambezi valley ecosystem. This ecological niche lies in the common tsetse fly belt that harbors the highest tsetse population density in Southern Africa. Ecological factors such as climate, vegetation and rainfall found in this niche allow for a favorable interplay between wild reservoir hosts and vector tsetse flies. These ecological factors that influence the survival of a wide range of wildlife species provide adequate habitat for tsetse flies thereby supporting the coexistence of disease reservoir hosts and vector tsetse flies leading to prolonged persistence of trypanosomiasis in the area. On the other hand, increase in anthropogenic activities poses a significant threat of reducing the tsetse and wildlife habitat in the area. Herein, we demonstrate that while conservation of wildlife and biodiversity is an important preservation strategy of natural resources, it could serve as a long-term reservoir of wildlife trypanosomiasis. PMID:22693499

Munang'andu, Hetron Mweemba; Siamudaala, Victor; Munyeme, Musso; Nalubamba, King Shimumbo

2012-01-01

194

Control of a new active power filter using 3-D vector control  

Microsoft Academic Search

The growth in distorting loads has given an interest in the design of three-wire active power filters, switching circuits which can be installed in an installation and generate harmonic currents to neutralize the loads' distorting current. With no neutral, the currents have two degrees of freedom and can be represented by two-dimensional (2-D) vectors. This approach leads to a control

Ali Dastfan; Victor J. Gosbell; Don Platt

2000-01-01

195

Vector control programs in Saint Johns County, Florida and Guayas, Ecuador: successes and barriers to integrated vector management  

PubMed Central

Background Vector-borne diseases (VBDs) and mosquito control programs (MCPs) diverge in settings and countries, and lead control specialists need to be aware of the most effective control strategies. Integrated Vector Management (IVM) strategies, once implemented in MCPs, aim to reduce cost and optimize protection of the populations against VBDs. This study presents a strengths, weaknesses, opportunities, and threats (SWOT) analysis to compare IVM strategies used by MCPs in Saint Johns County, Florida and Guayas, Ecuador. This research evaluates MCPs strategies to improve vector control activities. Methods Methods included descriptive findings of the MCP operations. Information was obtained from vector control specialists, directors, and residents through field trips, surveys, and questionnaires. Evaluations of the strategies and assets of the control programs where obtained through SWOT analysis and within an IVM approach. Results Organizationally, the Floridian MCP is a tax-based District able to make decisions independently from county government officials, with the oversight of an elected board of commissioners. The Guayas program is directed by the country government and assessed by non-governmental organizations like the World health Organization. Operationally, the Floridian MCP conducts entomological surveillance and the Ecuadorian MCP focuses on epidemiological monitoring of human disease cases. Strengths of both MCPs were their community participation and educational programs. Weaknesses for both MCPs included limitations in budgets and technical capabilities. Opportunities, for both MCPs, are additional funding and partnerships with private, non-governmental, and governmental organizations. Threats experienced by both MCPs included political constraints and changes in the social and ecological environment that affect mosquito densities and control efforts. IVM pillars for policy making were used to compare the information among the programs. Differences included how the Ecuadorian MCP relies heavily on the community for vector control while the American MCP relies on technologies and research. Conclusion IVM based recommendations direct health policy leaders toward improving surveillance systems both entomologically and epidemiologically, improving community risk perceptions by integrating components of community participation, maximizing resources though the use of applied research, and protecting the environment by selecting low-risk pesticides. Outcomes of the research revealed that inter-sectorial and multidisciplinary interventions are critical to improve public health. PMID:24990155

2014-01-01

196

Multichannel vector field control module for LLRF control of superconducting cavities  

SciTech Connect

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

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

2007-06-01

197

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

PubMed Central

Malaria vectors in sub-Saharan Africa have proven themselves very difficult adversaries in the global struggle against malaria. Decades of anti-vector interventions have yielded mixed results—with successful reductions in transmission in some areas and limited impacts in others. These varying successes can be ascribed to a lack of universally effective vector control tools, as well as the development of insecticide resistance in mosquito populations. Understanding the impact of vector control on mosquito populations is crucial for planning new interventions and evaluating existing ones. However, estimates of population size changes in response to control efforts are often inaccurate because of limitations and biases in collection methods. Attempts to evaluate the impact of vector control on mosquito effective population size (Ne) have produced inconclusive results thus far. Therefore, we obtained data for 13–15 microsatellite markers for more than 1,500 mosquitoes representing multiple time points for seven populations of three important vector species—Anopheles gambiae, An. melas, and An. moucheti—in Equatorial Guinea. These populations were exposed to indoor residual spraying or long-lasting insecticidal nets in recent years. For comparison, we also analyzed data from two populations that have no history of organized vector control. We used Approximate Bayesian Computation to reconstruct their demographic history, allowing us to evaluate the impact of these interventions on the effective population size. In six of the seven study populations, vector control had a dramatic impact on the effective population size, reducing Ne between 55%–87%, the exception being a single An. melas population. In contrast, the two negative control populations did not experience a reduction in effective population size. This study is the first to conclusively link anti-vector intervention programs in Africa to sharply reduced effective population sizes of malaria vectors. PMID:23271973

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

2012-01-01

198

Human African trypanosomiasis of the CNS: current issues and challenges  

PubMed Central

Human African trypanosomiasis (HAT), also known as sleeping sickness, is a major cause of mortality and morbidity in sub-Saharan Africa. Current therapy with melarsoprol for CNS HAT has unacceptable side-effects with an overall mortality of 5%. This review discusses the issues of diagnosis and staging of CNS disease, its neuropathogenesis, and the possibility of new therapies for treating late-stage disease. PMID:14966556

Kennedy, Peter G.E.

2004-01-01

199

Vector transmission regulates immune control of Plasmodium virulence  

PubMed Central

Defining mechanisms by which Plasmodium virulence is regulated is central to understanding the pathogenesis of human malaria. Serial blood passage of Plasmodium through rodents1-3, primates4 or humans5 increases parasite virulence, suggesting that vector transmission regulates Plasmodium virulence within the mammalian host. In agreement, disease severity can be modified by vector transmission6-8, which is assumed to ‘reset’ Plasmodium to its original character3. However, direct evidence that vector transmission regulates Plasmodium virulence is lacking. Here we utilise mosquito transmission of serially blood passaged (SBP) Plasmodium chabaudi chabaudi9 to interrogate regulation of parasite virulence. Analysis of SBP P.c. chabaudi before and after mosquito transmission demonstrates that vector transmission intrinsically modifies the asexual blood-stage parasite, which in turn, modifies the elicited mammalian immune response, which in turn, attenuates parasite growth and associated pathology. Attenuated parasite virulence associates with modified expression of the pir multi-gene family. Vector transmission of Plasmodium therefore regulates gene expression of probable variant antigens in the erythrocytic cycle, modifies the elicited mammalian immune response, and thus regulates parasite virulence. These results place the mosquito at the centre of our efforts to dissect mechanisms of protective immunity to malaria for the development of an effective vaccine. PMID:23719378

Spence, Philip J.; Jarra, William; Lévy, Prisca; Reid, Adam J.; Chappell, Lia; Brugat, Thibaut; Sanders, Mandy; Berriman, Matthew; Langhorne, Jean

2013-01-01

200

Necessary conditions of optimality for vector-valued impulsive control problems  

Microsoft Academic Search

A vector-valued impulsive control problem is considered whose dynamics, defined by a differential inclusion, are such that the vector fields associated with the singular term do not satisfy the so-called Frobenius condition. A concept of robust solution based on a new reparametrization procedure is adopted in order to derive necessary conditions of optimality. These conditions are obtained by taking a

Fernando Lobo Pereira; Geraldo Nunes Silva

2000-01-01

201

Rigid Body Attitude Control Using a Single Vector Measurement and Gyro  

Microsoft Academic Search

Most existing methods for satellite attitude control assume that full knowledge of satellite attitude is available by algebraic manipulation of at least two vector measurements from attitude sensors such as Sun, Earth-horizon, Earth-magnetic or star tracker sensors. Kalman filtering is usually used when only one vector measurement is available, however, asymptotic stability of nonlinear and uncertain dynamics of satellite is

Alireza Khosravian; Mehrzad Namvar

2012-01-01

202

Subolesin/Akirin vaccines for the control of arthropod vectors and vectorborne pathogens.  

PubMed

Diseases transmitted by arthropod vectors such as mosquitoes, ticks and sand flies greatly impact human and animal health, and therefore, their control is important for the eradication of vectorborne diseases (VBD). Vaccination is an environmentally friendly alternative for vector control that allows control of several VBD by targeting their common vector. Recent results have suggested that subolesin (SUB) and its orthologue in insects, akirin (AKR) are good candidate antigens for the control of arthropod vector infestations and pathogen infection. SUB was discovered as a tick-protective antigen in Ixodes scapularis. Vaccination trials with recombinant SUB/AKR demonstrated effective control of arthropod vector infestations in various hard and soft tick species, mosquitoes, sand flies, poultry red mites and sea lice by reducing their numbers, weight, oviposition, fertility and/or moulting. SUB/AKR vaccination also reduced tick infection with tickborne pathogens, Anaplasma phagocytophilum, A. marginale, Babesia bigemina and Borrelia burgdorferi. The effect of vaccination on different hosts, vector species, developmental stages and vectorborne pathogen infections demonstrated the feasibility of SUB/AKR universal vaccines for the control of multiple vector infestations and for reduction in VBD. PMID:24589118

de la Fuente, J; Moreno-Cid, J A; Galindo, R C; Almazan, C; Kocan, K M; Merino, O; Perez de la Lastra, J M; Estrada-Peña, A; Blouin, E F

2013-11-01

203

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

Microsoft Academic Search

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

Yuksel Oguz; Mehmet Dede

2011-01-01

204

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

NASA Astrophysics Data System (ADS)

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.

Yoshitani, Naoharu

205

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...

206

Plasma neuronal specific enolase: a potential stage diagnostic marker in human African trypanosomiasis  

PubMed Central

Background This study was carried out to determine the potential of neuronal specific enolase (NSE) as a stage diagnostic marker in human African trypanosomiasis. Methods Plasma and cerebrospinal fluid were obtained from a cohort of Trypanosoma brucei rhodesiense-infected patients and non-infected controls. Neuronal specific enolase concentrations were measured by ELISA and analysed in relation to diagnosis and disease-stage data. Results Plasma NSE concentration was significantly increased in late-stage patients (median 21 ng/ml), compared to the control (median 11 ng/ml), but not in early-stage patients (median 5.3 ng/ml). Cerebrospinal fluid NSE concentration did not vary between stages. Conclusion Plasma NSE is a potential stage diagnostic in this cohort and merits further investigation. PMID:24789741

Sternberg, Jeremy M.; Mitchell, Julia A.

2014-01-01

207

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

PubMed Central

Many of the most dangerous human diseases are transmitted by insect vectors. After decades of repeated insecticide use, all of these vector species have demonstrated the capacity to evolve resistance to insecticides. Insecticide resistance is generally considered to undermine control of vector-transmitted diseases because it increases the number of vectors that survive the insecticide treatment. Disease control failure, however, need not follow from vector control failure. Here, we review evidence that insecticide resistance may have an impact on the quality of vectors and, specifically, on three key determinants of parasite transmission: vector longevity, competence, and behaviour. We argue that, in some instances, insecticide resistance is likely to result in a decrease in vector longevity, a decrease in infectiousness, or in a change in behaviour, all of which will reduce the vectorial capacity of the insect. If this effect is sufficiently large, the impact of insecticide resistance on disease management may not be as detrimental as previously thought. In other instances, however, insecticide resistance may have the opposite effect, increasing the insect's vectorial capacity, which may lead to a dramatic increase in the transmission of the disease and even to a higher prevalence than in the absence of insecticides. Either way—and there may be no simple generality—the consequence of the evolution of insecticide resistance for disease ecology deserves additional attention. PMID:20700451

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

2010-01-01

208

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

E-print Network

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 ...

Gianotti, Rebecca L. (Rebecca Louise)

2008-01-01

209

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

E-print Network

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 ...

Bomblies, Arne

210

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

Microsoft Academic Search

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

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

2003-01-01

211

Microprocessor-Based Vector Control System for Induction Motor Drives with Rotor Time Constant Identification Function  

Microsoft Academic Search

A microprocessor-based high-performance vector control system for induction motor drives is discussed. In this system the high-performance current control method is employed, which can operate stably even when the saturation of a supplied voltage occurs. To estimate the rotor flux vector accurately, the powerful identification method of the rotor time constant is investigated, which does not require additional sensors for

Masato Koyama; Masao Yano; Isao Kamiyama; Sadanari Yano

1986-01-01

212

Solid rocket booster thrust vector control subsystem test report (D-1)  

NASA Technical Reports Server (NTRS)

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 performance of the auxiliary power unit. The possibility of components malfunction is also discussed.

Pagan, B.

1978-01-01

213

Implementation of speed-sensor-less field-oriented vector control using adaptive sliding observers  

Microsoft Academic Search

The authors describe the design method for a robust adaptive sliding observer which realizes speed-sensorless field-oriented vector control of AC motor drives. The speed-sensorless field oriented vector control system using the adaptive sliding observer was implemented. The basic characteristics of the proposed system and the design method against parameter deviation were studied experimentally. In the present system, the steady state

Shinji Doki; Somboon Sangwongwanich; Shigeru Okuma

1992-01-01

214

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

Microsoft Academic Search

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

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

2011-01-01

215

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

E-print Network

A KALMAN FILTERING TECHNIQUE FOR SPACECRAFT ATTITUDE DETERMINATION AND CONTROL USING GIBBS VECTOR A Thesis by GREGORY STEPHEN TALLANT Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE August 1988 Major Subject: Aerospace Engineering A KALMAN FILTERING TECHNIQUE FOR SPACECRAFT ATTITUDE DETERMINATION AND CONTROL USING GIBBS VECTOR A Thesis by GREGORY STEPHEN TALLANT Approved as to style and content by...

Tallant, Gregory Stephen

1988-01-01

216

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

NASA Technical Reports Server (NTRS)

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.

Bates, Lisa B.; Young, David T.

2012-01-01

217

A Simple Design Method Based on Vector Control of AC Machines with LC Filter  

NASA Astrophysics Data System (ADS)

This paper presents a simple voltage control system of AC machines using PWM voltage source inverter with output LC filters. By assuming a motor as a current source, the voltage is controlled by a simple proportional differential (PD) control. The vector control and PD control can be separately controlled in this system. A method for disturbance rejection is also described. The effectiveness of the proposed method is verified by simulations and experiments.

Saito, Ryosuke; Kubota, Hisao

218

Malaria transmission and vector behaviour in a forested malaria focus in central Vietnam and the implications for vector control  

PubMed Central

Background In Vietnam, malaria is becoming progressively restricted to specific foci where human and vector characteristics alter the known malaria epidemiology, urging for alternative or adapted control strategies. Long-lasting insecticidal hammocks (LLIH) were designed and introduced in Ninh Thuan province, south-central Vietnam, to control malaria in the specific context of forest malaria. An entomological study in this specific forested environment was conducted to assess the behavioural patterns of forest and village vectors and to assess the spatio-temporal risk factors of malaria transmission in the province. Methods Five entomological surveys were conducted in three villages in Ma Noi commune and in five villages in Phuoc Binh commune in Ninh Thuan Province, south-central Vietnam. Collections were made inside the village, at the plot near the slash-and-burn fields in the forest and on the way to the forest. All collected mosquito species were subjected to enzyme-linked immunosorbent assay (ELISA) to detect Plasmodium in the head-thoracic portion of individual mosquitoes after morphological identification. Collection data were analysed by use of correspondence and multivariate analyses. Results The mosquito density in the study area was low with on average 3.7 anopheline bites per man-night and 17.4 culicine bites per man-night. Plasmodium-infected mosquitoes were only found in the forest and on the way to the forest. Malaria transmission in the forested malaria foci was spread over the entire night, from dusk to dawn, but was most intense in the early evening as nine of the 13 Plasmodium positive bites occurred before 21H. The annual entomological inoculation rate of Plasmodium falciparum was 2.2 infective bites per person-year to which Anopheles dirus s.s. and Anopheles minimus s.s. contributed. The Plasmodium vivax annual entomological inoculation rate was 2.5 infective bites per person-year with Anopheles sawadwongporni, Anopheles dirus s.s. and Anopheles pampanai as vectors. Conclusion The vector behaviour and spatio-temporal patterns of malaria transmission in Southeast Asia impose new challenges when changing objectives from control to elimination of malaria and make it necessary to focus not only on the known main vector species. Moreover, effective tools to prevent malaria transmission in the early evening and in the early morning, when the treated bed net cannot be used, need to be developed. PMID:21182774

2010-01-01

219

Space-vector PWM voltage control with optimized switching strategy  

Microsoft Academic Search

Since space vector modulation offers superior performance with respect to other modulation techniques, it is important to establish the sequencing strategy which is best suited for variable-frequency AC drives. The characteristics of regular direct-direct (DD) and inverted direct-inverse (DI) sequencing strategies are investigated both analytically and experimentally. The two strategies are compared with respect to the current ripple, the current

V. R. Stefanovic; S. N. Vukosavic

1992-01-01

220

Olfactory disruption: toward controlling important insect vectors of disease.  

PubMed

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 results of studies aimed at a more thorough understanding of the mode of action of repellents and discuss the implications of these findings for future research and development of novel or improved repellents. PMID:25623338

Sparks, Jackson T; Bohbot, Jonathan D; Dickens, Joseph C

2015-01-01

221

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

PubMed Central

Background Chagas disease is a major neglected tropical disease with deep socio-economical effects throughout Central and South America. Vector control programs have consistently reduced domestic populations of triatomine vectors, but non-domiciliated vectors still have to be controlled efficiently. Designing control strategies targeting these vectors is challenging, as it requires a quantitative description of the spatio-temporal dynamics of village infestation, which can only be gained from combinations of extensive field studies and spatial population dynamic modelling. Methodology/Principal Findings A spatially explicit population dynamic model was combined with a two-year field study of T. dimidiata infestation dynamics in the village of Teya, Mexico. The parameterized model fitted and predicted accurately both intra-annual variation and the spatial gradient in vector abundance. Five different control strategies were then applied in concentric rings to mimic spatial design targeting the periphery of the village, where vectors were most abundant. Indoor insecticide spraying and insect screens reduced vector abundance by up to 80% (when applied to the whole village), and half of this effect was obtained when control was applied only to the 33% of households closest to the village periphery. Peri-domicile cleaning was able to eliminate up to 60% of the vectors, but at the periphery of the village it has a low effect, as it is ineffective against sylvatic insects. The use of lethal traps and the management of house attractiveness provided similar levels of control. However this required either house attractiveness to be null, or ?5 lethal traps, at least as attractive as houses, to be installed in each household. Conclusion/Significance Insecticide and insect screens used in houses at the periphery of the village can contribute to reduce house infestation in more central untreated zones. However, this beneficial effect remains insufficient to allow for a unique spatially targeted strategy to offer protection to all households. Most efficiently, control should combine the use of insect screens in outer zones to reduce infestation by both sylvatic and peri-domiciliated vectors, and cleaning of peri-domicile in the centre of the village where sylvatic vectors are absent. The design of such spatially mixed strategies of control offers a promising avenue to reduce the economic cost associated with the control of non-domiciliated vectors. PMID:21610862

Barbu, Corentin; Dumonteil, Eric; Gourbière, Sébastien

2011-01-01

222

Fuel-optimal angular momentum vector control for spinning and dual-spin spacecraft.  

NASA Technical Reports Server (NTRS)

The problem of fuel-optimal small-angle reorientation of the spin axis of a spinning or dual-spin spacecraft is examined. The results obtained show significant improvements over previously published optimization studies by virtue of the introduction of two innovations: (1) mass-explusion active control is utilized for angular momentum vector pointing only, with passive damping relied upon for stable vehicles to attenuate vehicle coning about the angular momentum vector, so that the task of the active controller changes from spin axis control to angular momentum vector control, and (2) several options are considered for type, number, and location of attitude control jets. The first of these considerations introduces a target set which is a smooth, two-dimensional linear manifold in the four-dimensional state space, whereas previous studies have adopted the origin as the target set. The second innovation amounts to consideration of a spectrum of control restraint sets.

Larson, V.; Likins, P.

1973-01-01

223

Vector controlled induction machines for stand-alone wind energy applications  

Microsoft Academic Search

This paper describes the system and control structures for vector controlled induction generators used for variable speed, wind energy conversion (WEC) systems. The paper focuses on WEC systems feeding an isolated load or weak grid since for such systems the generated voltage and power flow must be regulated by the WEC system itself and the control structures are not trivial.

R. S. Pena; R. J. Cardenas; G. M. Asher; J. C. Clare

2000-01-01

224

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

Microsoft Academic Search

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

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

1990-01-01

225

Vector control strategies for single-phase induction motor drive systems  

Microsoft Academic Search

This paper discusses vector control strategies for single-phase motor drive systems operating with two windings. A model is proposed and used to derive control laws for single-phase motor drive systems. Such model is also employed to introduce the double-sequence controller. Simulation and experimental results are provided to illustrate the operation of the proposed drive systems.

M. B. de Rossiter Correa; C. B. Jacobina; E. R. C. da Silva; A. M. N. Lima

2004-01-01

226

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

Microsoft Academic Search

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

Marian P. Kazmierkowski; Andrzej B. Kasprowicz

1995-01-01

227

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

Microsoft Academic Search

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

Zheng Li

2010-01-01

228

Space Vector Modulation based Field Oriented Control scheme for Brushless DC motors  

Microsoft Academic Search

This paper focuses on various aspects of Space Vector Modulation based Field Oriented Control of Trapezoidal Permanent Magnet Synchronous Motors. The purpose is to introduce in a concise manner the fundamental theory, main results and practical applications of Field Oriented Control (FOC) for Brushless DC motors. The primary focus is on controlling the motor in d-q axis using field oriented

Joseph P John; S. Suresh Kumar; B. Jaya

2011-01-01

229

Experimental and theoretical comparison of the Probe Thrust Vector Control concept  

NASA Technical Reports Server (NTRS)

A concept that offers an alternate method for thrust vector control of liquid or solid propellant rockets is the use of a solid body or probe that is inserted on demand through the wall of the rocket nozzle. This Probe Thrust Vector Control (PTVC) concept is an alternative to that of a gimbaled nozzle or a Liquid Injection Thrust Vector control system. The viability of the PTVC concept can be assessed either experimentally and/or with the use of CFD. A purely experimental assessment is time consuming and expensive, whereas a CFD assessment is time- and cost-effective. Two key requirements of the concept are PTVC vectoring performance and active cooling requirements for the probe to maintain its thermal and structural integrity. The objective of the work reported here is presentation of experimental subscale cold flow tests and comparison of these tests with CFD predictions and the response time of the PTVC system.

Cavalleri, Robert; Tiarn, Weihnurng; Lewis, Lynn

1991-01-01

230

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

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

231

System-level power loss sensitivity to various control variables in vector-controlled induction motor drives  

Microsoft Academic Search

Vector-controlled induction motor drives include several design and control variables that affect power losses. Flux may be weakened to reduce machine losses; switching and conduction losses in the inverter are reduced by adjusting the flux ripple and current hysteresis bands. This paper combines the machine and inverter to investigate the effects of various control variables on the total system power

Ali M. Bazzi; Veysel T. Buyukdegirmenci; Philip T. Krein

2012-01-01

232

Effects of plant water stress on vector feeding behaviors that control acquisition and inoculation of Xylella fastidiosa  

Technology Transfer Automated Retrieval System (TEKTRAN)

Feeding behavior by vectors of Xylella fastidiosa (Xf) such as the glassy-winged sharpshooter (GWSS), Homalodisca vitripennis, directly controls Xf transmission (especially acquisition and inoculation). The present study tested whether plant water stress affects vector performance of acquisition an...

233

The continuing problem of human African trypanosomiasis (sleeping sickness).  

PubMed

Human African trypanosomiasis, also known as sleeping sickness, is a neglected disease, and it continues to pose a major threat to 60 million people in 36 countries in sub-Saharan Africa. Transmitted by the bite of the tsetse fly, the disease is caused by protozoan parasites of the genus Trypanosoma and comes in two types: East African human African trypanosomiasis caused by Trypanosoma brucei rhodesiense and the West African form caused by Trypanosoma brucei gambiense. There is an early or hemolymphatic stage and a late or encephalitic stage, when the parasites cross the blood-brain barrier to invade the central nervous system. Two critical current issues are disease staging and drug therapy, especially for late-stage disease. Lumbar puncture to analyze cerebrospinal fluid will remain the only method of disease staging until reliable noninvasive methods are developed, but there is no widespread consensus as to what exactly defines biologically central nervous system disease or what specific cerebrospinal fluid findings should justify drug therapy for late-stage involvement. All four main drugs used for human African trypanosomiasis are toxic, and melarsoprol, the only drug that is effective for both types of central nervous system disease, is so toxic that it kills 5% of patients who receive it. Eflornithine, alone or combined with nifurtimox, is being used increasingly as first-line therapy for gambiense disease. There is a pressing need for an effective, safe oral drug for both stages of the disease, but this will require a significant increase in investment for new drug discovery from Western governments and the pharmaceutical industry. PMID:18756506

Kennedy, Peter G E

2008-08-01

234

Quantized control using vector differential pulse code modulation  

E-print Network

is assumed to be zero-mean and normal, and the initial state is asumed to be a normal random vector, wk ~ N(O, Wk), ~v & N(O, Vk) N(x &Po) where Wk and Vk represent the covariances of the driving noise ~w and the measure ement noise ~v, respectively... extrapolation: k I = ek-IPk-Iek-I + Wk-I (3. 5d) State estimate update: = a~c)k-I Kk(&x k a )k-I) Error covariance update: (I-KkHk) Pk ) k-I (3. 5f) 32 Kalman Gain Matrix: T -1 k = Pk( k ]Hk~HkPk( k-1Hk Vk& This formulation assumes...

Tinnin, Dorothy Joy

1982-01-01

235

Prevention and control of neglected tropical diseases: overview of randomized trials, systematic reviews and meta-analyses  

PubMed Central

Abstract Objective To analyse evidence from randomized controlled trials (RCTs) on the prevention and control of neglected tropical diseases (NTDs) and to identify areas where evidence is lacking. Methods The Cochrane Central Register of Controlled Trials and PubMed were searched for RCTs and the Cochrane Database of Systematic Reviews and PubMed were searched for meta-analyses and systematic reviews, both from inception to 31 December 2012. Findings Overall, 258 RCTs were found on American trypanosomiasis, Buruli ulcer, dengue, geohelminth infection, leishmaniasis, leprosy, lymphatic filariasis, onchocerciasis, rabies, schistosomiasis or trachoma. No RCTs were found on cysticercosis, dracunculiasis, echinococcosis, foodborne trematodes, or human African trypanosomiasis. The most studied diseases were geohelminth infection (51 RCTs) and leishmaniasis (46 RCTs). Vaccines, chemoprophylaxis and interventions targeting insect vectors were evaluated in 113, 99 and 39 RCTs, respectively. Few addressed how best to deliver preventive chemotherapy, such as the choice of dosing interval (10) or target population (4), the population coverage needed to reduce transmission (2) or the method of drug distribution (1). Thirty-one publications containing 32 systematic reviews (16 with and 16 without meta-analyses) were found on American trypanosomiasis, dengue, geohelminths, leishmaniasis, leprosy, lymphatic filariasis, onchocerciasis, schistosomiasis or trachoma. Together, they included only 79 of the 258 published RCTs (30.6%). Of 36 interventions assessed, 8 were judged effective in more than one review. Conclusion Few RCTs on the prevention or control of the principal NTDs were found. Trials on how best to deliver preventive chemotherapy were particularly rare. PMID:24839325

Kappagoda, Shanthi

2014-01-01

236

Omni-axis secondary injection thrust vector control system  

NASA Technical Reports Server (NTRS)

The concept, development, design study and preliminary analysis and layout of the required digital logic scheme to be used for injection valve control are presented. An application and optimization study of an Omni-Axis Secondary Injection Control System applicable to the proposed Space Shuttle Pressure Fed Engine is reported. Technical definition and analysis control procedures and test routines, as well as a supporting set of drawing sketches and reference manual, are enclosed.

Kirkley, D. J.

1973-01-01

237

Sensorless vector control of induction machines for variable-speed wind energy applications  

Microsoft Academic Search

A sensorless vector-control strategy for an induction generator in a grid-connected wind energy conversion system is presented. The sensorless control system is based on a model reference adaptive system (MRAS) observer to estimate the rotational speed. In order to tune the MRAS observer and compensate for the parameter variation and uncertainties, a separate estimation of the speed is obtained from

Roberto Cárdenas; Rubén Peña

2004-01-01

238

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

239

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

Microsoft Academic Search

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

C. Schauder

1992-01-01

240

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

241

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

242

A new space vector based control method for UPS systems powering nonlinear and unbalanced loads  

Microsoft Academic Search

In this paper a new real time space vector based control strategy is presented for 3-phase UPS systems powering nonlinear and unbalanced loads. The proposed control strategy generates the inverter reference and gating signals in closed loop and guarantees high quality output voltages at the load terminals. The approach, which is implemented on a DSP, adapts to a wide variation

Uffe Bomp Jensen; Prasad N. Enjeti; Frede Blaabjerg

2000-01-01

243

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

Microsoft Academic Search

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 was implemented

Colin Schauder

1989-01-01

244

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

245

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

Microsoft Academic Search

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

Takayoshi Matsuo; Thomas A. Lipo

1985-01-01

246

Nonlinear stabilizer with nonconstant vector ? for the Pendubot based on controlled Lagrangians method  

Microsoft Academic Search

This paper concerns stabilization of the Pendubot by controller design for underactuated mechanical systems with two degrees of freedom (DOF) based on the controlled Lagrangians method. A solution with a nonconstant vector Gamma is found for the kinetic energy equation in the necessary and sufficient matching condition. As a contribution, the range of system parameters is enlarged in which the

Mao-Qing Li

2009-01-01

247

Dengue vector control strategies in an urban setting: an economic modelling assessment  

PubMed Central

Summary Background An estimated 2·5 billion people are at risk of dengue. Incidence of dengue is especially high in resource-constrained countries, where control relies mainly on insecticides targeted at larval or adult mosquitoes. We did epidemiological and economic assessments of different vector control strategies. Methods We developed a dynamic model of dengue transmission that assesses the evolution of insecticide resistance and immunity in the human population, thus allowing for long-term evolutionary and immunological effects of decreased dengue transmission. We measured the dengue health burden in terms of disability-adjusted life-years (DALYs) lost. We did a cost-effectiveness analysis of 43 insecticide-based vector control strategies, including strategies targeted at adult and larval stages, at varying efficacies (high-efficacy [90% mortality], medium-efficacy [60% mortality], and low-efficacy [30% mortality]) and yearly application frequencies (one to six applications). To assess the effect of parameter uncertainty on the results, we did a probabilistic sensitivity analysis and a threshold analysis. Findings All interventions caused the emergence of insecticide resistance, which, with the loss of herd immunity, will increase the magnitude of future dengue epidemics. In our model, one or more applications of high-efficacy larval control reduced dengue burden for up to 2 years, whereas three or more applications of adult vector control reduced dengue burden for up to 4 years. The incremental cost-effectiveness ratios of the strategies for two high-efficacy adult vector control applications per year was US$615 per DALY saved and for six high-efficacy adult vector control applications per year was $1267 per DALY saved. Sensitivity analysis showed that if the cost of adult control was more than 8·2 times the cost of larval control then all strategies based on adult control became dominated. Interpretation Six high-efficacy adult vector control applications per year has a cost-effectiveness ratio that will probably meet WHO's standard for a cost-effective or very cost-effective intervention. Year-round larval control can be counterproductive, exacerbating epidemics in later years because of evolution of insecticide resistance and loss of herd immunity. We suggest the reassessment of vector control policies that are based on larval control only. Funding The Fulbright Programme, CAPES (Brazilian federal agency for post-graduate education), the Miriam Burnett trust, and the Notsew Orm Sands Foundation. PMID:21546076

Luz, Paula Mendes; Vanni, Tazio; Medlock, Jan; Paltiel, A David; Galvani, Alison P

2012-01-01

248

Fuzzy adaptive vector control of induction motor drives  

Microsoft Academic Search

This paper deals with the design and experimental realization of a model reference adaptive control (MRAC) system for the speed control of indirect field-oriented (IFO) induction motor drives based on using fuzzy laws for the adaptive process and a neuro-fuzzy procedure to optimize the fuzzy rules. Variation of the rotor time constant is also accounted for by performing a fuzzy

Emanuele Cerruto; Alfio Consoli; Angelo Raciti; Antonio Testa

1997-01-01

249

Study of evoked potentials in human African trypanosomiasis.  

PubMed

Human African trypanosomiasis or sleeping sickness has a stage of neurological involvement characterized by the onset of diffuse meningoencephalitis with sleep disturbances and decreased wakefulness. The pathogenesis of this disease is not well understood. We studied auditory, visual, sensory, and motor evoked potentials in 16 patients with trypanosomiasis in the early stage of meningoencephalitis. In all patients, the brain-stem auditory evoked response (BAER) and the pattern-reversal visual evoked response (PVER) were normal. On the other hand, abnormalities of the somatosensory evoked response (SSER) or the motor evoked response (MER) were found in only five cases; however, their relationship to the illness could not be definitely confirmed. The study results indicate that the evaluated pathways were essentially intact, in particular at the level of the brain-stem in the early stage of the disease. Sleep disturbances and decreased wakefulness noted at this stage were thus linked more closely to functional involvement at the level of the sleep centres than to any detectable specific anatomic lesion. PMID:1495120

Tabaraud, F; Hugon, J; Tapie, P; Buguet, A; Lonsdorfer, A; Gati, R; Doua, F; Dumas, M

1992-08-01

250

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

PubMed Central

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

Gürtler, Ricardo E

2011-01-01

251

Fluidic scale model multi-plane thrust vector control test results  

NASA Technical Reports Server (NTRS)

An experimental investigation has been conducted at the NASA Langley 16-Foot Transonic Tunnel Static Test Facility to determine the concept feasibility of using fluidics to achieve multiplane thrust vector control in a 2D convergent-divergent (2D-CD) fixed aperture nozzle. Pitch thrust vector control is achieved by injection of flow through a slot in the divergent flap into the primary nozzle flow stream. Yaw vector control results from secondary air delivered tangentially to vertical Coanda flaps. These flaps are offset laterally and aligned parallel to the primary nozzle side walls. All tests were conducted at static (no external flow) conditions. Flow visualization was conducted using a paint flow technique and Focus Schlieren. Significant levels of pitch deflection angles (19 deg) were achieved at low pressure ratios and practical levels (14 deg) resulted at typical intermediate power settings. The ability of the Coanda surface blowing concept to produce yaw deflection was limited to NPR not greater than 4.

Chiarelli, Charles; Johnsen, Raymond K.; Shieh, Chih F.; Wing, David J.

1993-01-01

252

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...

253

The ecological dimensions of vector-borne disease research and control.  

PubMed

Alarming trends in the resurgence of vector-borne diseases are anticipated to continue unless more effective action is taken to address the variety of underlying causes. Social factors, anthropogenic environmental modifications and/or ecological changes appear to be the primary drivers. The ecological dimension of vector-borne disease research and management is a pervasive element because this issue is essentially an ecological problem with biophysical, social, and economic dimensions. However there is often a lack of clarity about the ecological dimension, the field of ecology (e.g. role, limitations), and related concepts pertinent to ecosystem approaches to health. An ecological perspective can provide foresight into the appropriateness of interventions, provide answers to unexpected vector control responses, and contribute to effective management solutions in an ever-changing environment. The aim of this paper is to explore the ecological dimension of vector-borne diseases and to provide further clarity about the role of 'ecological thinking' in the development and implementation of vector control activities (i.e. ecosystem approaches to vector-borne diseases). PMID:19287860

Ellis, Brett R; Wilcox, Bruce A

2009-01-01

254

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

PubMed Central

We are developing a set of ontologies dealing with vector-borne diseases as well as the arthropod vectors that transmit them. After building ontologies for mosquito and tick anatomy we continued this project with an ontology of insecticide resistance followed by a series of ontologies that describe malaria as well as physiological processes of mosquitoes that are relevant to, and involved in, disease transmission. These will later be expanded to encompass other vector-borne diseases as well as non-mosquito vectors. The aim of the whole undertaking, which is worked out in the frame of the international IDO (Infectious Disease Ontology) project, is to provide the community with a set of ontological tools that can be used both in the development of specific databases and, most importantly, in the construction of decision support systems (DSS) to control these diseases. PMID:20363364

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

2010-01-01

255

Delivery of antihuman African trypanosomiasis drugs across the blood-brain and blood-CSF barriers.  

PubMed

Human African trypanosomiasis (HAT or sleeping sickness) is a potentially fatal disease caused by the parasite, Trypanosoma brucei sp. The parasites are transmitted by the bite of insect vectors belonging to the genus Glossina (tsetse flies) and display a life cycle strategy that is equally spread between human and insect hosts. T.b. gambiense is found in western and central Africa whereas, T.b. rhodesiense is found in eastern and southern Africa. The disease has two clinical stages: a blood stage after the bite of an infected tsetse fly, followed by a central nervous system (CNS) stage where the parasite penetrates the brain; causing death if left untreated. The blood-brain barrier (BBB) makes the CNS stage difficult to treat because it prevents 98% of all known compounds from entering the brain, including some anti-HAT drugs. Those that do enter the brain are toxic compounds in their own right and have serious side effects. There are only a few drugs available to treat HAT and those that do are stage specific. This review summarizes the incidence, diagnosis, and treatment of HAT and provides a close examination of the BBB transport of anti-HAT drugs and an overview of the latest drugs in development. PMID:25307219

Sekhar, Gayathri N; Watson, Christopher P; Fidanboylu, Mehmet; Sanderson, Lisa; Thomas, Sarah A

2014-01-01

256

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

Microsoft Academic Search

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

M. A. Rahman; M. A. Hoque

1998-01-01

257

A comparative analysis of the relative efficacy of vector-control strategies against dengue fever.  

PubMed

Dengue is considered one of the most important vector-borne infection, affecting almost half of the world population with 50 to 100 million cases every year. In this paper, we present one of the simplest models that can encapsulate all the important variables related to vector control of dengue fever. The model considers the human population, the adult mosquito population and the population of immature stages, which includes eggs, larvae and pupae. The model also considers the vertical transmission of dengue in the mosquitoes and the seasonal variation in the mosquito population. From this basic model describing the dynamics of dengue infection, we deduce thresholds for avoiding the introduction of the disease and for the elimination of the disease. In particular, we deduce a Basic Reproduction Number for dengue that includes parameters related to the immature stages of the mosquito. By neglecting seasonal variation, we calculate the equilibrium values of the model's variables. We also present a sensitivity analysis of the impact of four vector-control strategies on the Basic Reproduction Number, on the Force of Infection and on the human prevalence of dengue. Each of the strategies was studied separately from the others. The analysis presented allows us to conclude that of the available vector control strategies, adulticide application is the most effective, followed by the reduction of the exposure to mosquito bites, locating and destroying breeding places and, finally, larvicides. Current vector-control methods are concentrated on mechanical destruction of mosquitoes' breeding places. Our results suggest that reducing the contact between vector and hosts (biting rates) is as efficient as the logistically difficult but very efficient adult mosquito's control. PMID:24619807

Amaku, Marcos; Coutinho, Francisco Antonio Bezerra; Raimundo, Silvia Martorano; Lopez, Luis Fernandez; Nascimento Burattini, Marcelo; Massad, Eduardo

2014-03-01

258

Vector control of induction motors without shaft transducers  

Microsoft Academic Search

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.

A. Fratta; A. Vagati; F. Villata

1988-01-01

259

Spin vector control of a spinning space station  

NASA Technical Reports Server (NTRS)

Digital computer program simulates system and related functions. Program is intended for, but not limited to, altitude control studies of rotating space station. Russel's method of formulating and solving motion equations for system of rigid bodies connected by movable joints is applied. Program features are listed.

Hendricks, T.

1971-01-01

260

The effects of trypanosomiasis on rural economy with special reference to the Sudan, Bechuanaland and West Africa.  

PubMed

Trypanosomiasis, both of humans and of livestock, is one of the most important factors restricting economic development in Africa today. The present paper outlines how this disease is limiting agricultural, veterinary and forestry development in the Sudan, Bechuanaland and West Africa.The present tsetse-fly distribution is reviewed. Glossina palpalis and G. morsitans occur in the south Sudan and G. morsitans in the Ngamiland district of Bechuanaland; G. morsitans, G. palpalis and G. tachinoides are the most important species in West Africa.These tsetse flies have altered the cattle distribution in all three regions and, in addition to causing widespread disease, have created local overstocking problems in the tsetse-free grazing areas, and have enforced nomadism on breeding herds and economic loss in slaughter cattle along the trade cattle routes in West Africa.Human trypanosomiasis is not now such an urgent problem and public health measures have led to its control in all three areas.Increased agricultural development, which can be a successful and economic method of reclaiming land from tsetse flies, must be intensified in all three areas.Forest conservation policy comes into conflict with tsetse control measures only in West Africa.Detailed tsetse-fly surveys and research, on which future plans can be firmly based, are now urgently required. PMID:14001093

WILSON, S G; MORRIS, K R; LEWIS, I J; KROG, E

1963-01-01

261

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

PubMed Central

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

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

2012-01-01

262

A Vector Control for Grid-connected Wind Power Generation with Doubly Fed Induction Generator  

NASA Astrophysics Data System (ADS)

Recently, doubly fed induction generator (DFIG) and synchronous generator are mostly applied for wind power generation due to high efficiently for wind energy capture. An inverter system is required to control wind turbine speed and power factor in those generators. The inverter rating of the synchronous generator equals to generator rating. However, DFIG has the advantage that the inverter rating is about 25% to the generator rating. The paper describes a vector control of DFIG inter-connected to power line. The performance of proposed vector control is examined using power system simulation software PSCAD/EMTDC for the DFIG inter-connected to 6.6kv distribution line. The results show good dynamic responses and high accuracy to the stator active power control and the stator reactive power control.

Kai, Takaaki; Tanaka, Yuji; Kaneda, Hirotoshi; Kobayashi, Daichi; Tanaka, Akio

263

A Simplified Sensorless Vector Control Based on Average DC Bus Current for Fan Motor  

NASA Astrophysics Data System (ADS)

This paper describes a simplified sensorless vector control based on the average DC bus current for PMSM. This method can be used to design a drive control system at a relatively low cost because the microcontroller does not require a precise timer and the calculation load is slight. In the proposed method, one of the two possible current estimation processes is chosen according to the operation mode. First, the controller estimates d-axis current and identifies the back-EMF parameter in the synchronous operation mode at low speeds. The error in the back-EMF identification affects the efficiency of the proposed system, so it needs to be zero. Second, the controller estimates q-axis current in vector control mode. The identified parameter and q-axis current define voltage reference to realize high efficiency drive. The obtained experimental results confirm the effectiveness of the proposed method.

Sumita, Satoshi; Tobari, Kazuaki; Aoyagi, Shigehisa; Maeda, Daisuke

264

Analysis of Power Converter Losses in Vector Control System of a Self-Excited Induction Generator  

NASA Astrophysics Data System (ADS)

This paper provides analysis of losses in the hysteresis-driven three-phase power converter with IGBTs and free-wheeling diodes. The converter under consideration is part of the self-excited induction generator (SEIG) vector control system. For the analysis, the SEIG vector control system is used in which the induction generator iron losses are taken into account. The power converter losses are determined by using a suitable loss estimation algorithm reported in literature. The chosen algorithm allows the power converter losses to be determined both by type (switching/conduction losses) and by converter component (IGBT/diode losses). The overall power converter losses are determined over wide ranges of rotor speed, dc-link voltage and load resistance, and subsequently used for offline correction of the overall control system's losses (efficiency) obtained through control system simulations with an ideal power converter. The control system's efficiency values obtained after the correction are compared with the measured values.

Baši?, Mateo; Vukadinovi?, Dinko; Poli?, Miljenko

2014-03-01

265

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

PubMed

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

Clark, Gary G; Rubio-Palis, Yasmin

2012-06-01

266

Heritable strategies for controlling insect vectors of disease.  

PubMed

Mosquito-borne diseases are causing a substantial burden of mortality, morbidity and economic loss in many parts of the world, despite current control efforts, and new complementary approaches to controlling these diseases are needed. One promising class of new interventions under development involves the heritable modification of the mosquito by insertion of novel genes into the nucleus or of Wolbachia endosymbionts into the cytoplasm. Once released into a target population, these modifications can act to reduce one or more components of the mosquito population's vectorial capacity (e.g. the number of female mosquitoes, their longevity or their ability to support development and transmission of the pathogen). Some of the modifications under development are designed to be self-limiting, in that they will tend to disappear over time in the absence of recurrent releases (and hence are similar to the sterile insect technique, SIT), whereas other modifications are designed to be self-sustaining, spreading through populations even after releases stop (and hence are similar to traditional biological control). Several successful field trials have now been performed with Aedes mosquitoes, and such trials are helping to define the appropriate developmental pathway for this new class of intervention. PMID:24821918

Burt, Austin

2014-01-01

267

Heritable strategies for controlling insect vectors of disease  

PubMed Central

Mosquito-borne diseases are causing a substantial burden of mortality, morbidity and economic loss in many parts of the world, despite current control efforts, and new complementary approaches to controlling these diseases are needed. One promising class of new interventions under development involves the heritable modification of the mosquito by insertion of novel genes into the nucleus or of Wolbachia endosymbionts into the cytoplasm. Once released into a target population, these modifications can act to reduce one or more components of the mosquito population's vectorial capacity (e.g. the number of female mosquitoes, their longevity or their ability to support development and transmission of the pathogen). Some of the modifications under development are designed to be self-limiting, in that they will tend to disappear over time in the absence of recurrent releases (and hence are similar to the sterile insect technique, SIT), whereas other modifications are designed to be self-sustaining, spreading through populations even after releases stop (and hence are similar to traditional biological control). Several successful field trials have now been performed with Aedes mosquitoes, and such trials are helping to define the appropriate developmental pathway for this new class of intervention. PMID:24821918

Burt, Austin

2014-01-01

268

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

PubMed Central

Foamy virus (FV) vector systems have recently demonstrated their power as efficient gene transfer tools for different target tissues. Unfortunately, FVs cannot be naturally pseudotyped by heterologous viral glycoproteins due to an unusual particle morphogenesis involving a FV Env-dependent particle release process. Therefore, current FV vector systems are constrained to the broad host cell range provided by the cognate viral glycoprotein. We evaluated different approaches for pseudotyping of FV vectors, in which the specific FV Gag–Env interaction, essential for particle egress, is substituted by a small-molecule controlled heterodimerization (HD) system. In one system developed, one HD-domain (HDD) is fused to a membrane-targeting domain (MTD), such as the human immunodeficiency virus (HIV) Gag matrix (MA) subunit, with a second fused to the FV capsid protein. Coexpression of both components with different heterologous viral glycoproteins allowed an efficient, dimerizer-dependent pseudotyping of FV capsids. With this system FV vesicular stomatitis virus glycoprotein (VSV-G) pseudotype titers greater than 1 × 106 IU/ml were obtained, at levels comparable to authentic FV vector particles. As a proof-of-principle we demonstrate that Pac2 cells, naturally resistant to FV vectors, become permissive to FV VSV-G pseudotypes. Similar to other retroviral vectors, this FV pseudotyping system now enables adaptation of cell-specific targeting approaches for FVs. PMID:22472951

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

2012-01-01

269

Human African trypanosomiasis: quantitative and qualitative assessment of intrathecal immune response  

Microsoft Academic Search

Quantitative and qualitative techniques for assessment of the intrathecal humoral immune response in human African trypanosomiasis were compared, and their diagnostic potential for detection of the meningo-encephalitic stage of the disease was evaluated. Total and trypanosome specific immunoglobulin G (IgG) and IgM intra- thecal synthesis were studied in paired cerebrospinal fluid (CSF) and blood samples of 38 trypanosomiasis patients and

V. Lejon; C. J. M. Sindic; M.-P. Van Antwerpen; F. Doua; N. Dje; P. Solano; V. Jamonneau; I. Wouters; P. Buscher

2003-01-01

270

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

PubMed Central

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

Hashimoto, Ken; Yoshioka, Kota

2014-01-01

271

An innovative ecohealth intervention for Chagas disease vector control in Yucatan, Mexico  

PubMed Central

Background Non-domiciliated (intrusive) triatomine vectors remain a challenge for the sustainability of Chagas disease vector control as these triatomines are able to transiently (re-)infest houses. One of the best-characterized examples is Triatoma dimidiata from the Yucatan peninsula, Mexico, where adult insects seasonally infest houses between March and July. Methods We focused our study on three rural villages in the state of Yucatan, Mexico, in which we performed a situation analysis as a first step before the implementation of an ecohealth (ecosystem approach to health) vector control intervention. Results The identification of the key determinants affecting the transient invasion of human dwellings by T. dimidiata was performed by exploring associations between bug presence and qualitative and quantitative variables describing the ecological, biological and social context of the communities. We then used a participatory action research approach for implementation and evaluation of a control strategy based on window insect screens to reduce house infestation by T. dimidiata. Conclusions This ecohealth approach may represent a valuable alternative to vertically-organized insecticide spraying. Further evaluation may confirm that it is sustainable and provides effective control (in the sense of limiting infestation of human dwellings and vector/human contacts) of intrusive triatomines in the region. PMID:25604765

Waleckx, Etienne; Camara-Mejia, Javier; Ramirez-Sierra, Maria Jesus; Cruz-Chan, Vladimir; Rosado-Vallado, Miguel; Vazquez-Narvaez, Santos; Najera-Vazquez, Rosario; Gourbière, Sébastien; Dumonteil, Eric

2015-01-01

272

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

Microsoft Academic Search

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

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

1999-01-01

273

Input Vector Control for Post-Silicon Leakage Current Minimization in the Presence of Manufacturing Variability  

E-print Network

Input Vector Control for Post-Silicon Leakage Current Minimization in the Presence of Manufacturing for an inverter of nominal size in 0.18um model from MOSIS that is simulated using the leakage current in CadenceA10x leakage 1Input Figure 1: Series inverters and their leakage currents. If A has the nominal

Potkonjak, Miodrag

274

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...

275

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

276

Sensorless vector control of induction machine using high frequency current injection  

Microsoft Academic Search

This paper describes a new approach to estimate the rotor angle of an induction machine from measured terminal voltages and currents using high frequency current injection for sensorless vector control. The proposed scheme is independent of load variation since the rotor angle is derived by using only the injected d-axis current, also it is robust to parameter variation because only

Sung-Il Yong; Jong-Woo Choi; Seung-Ki Sul

1994-01-01

277

A new approach to vector control for a linear induction motor considering end effects  

Microsoft Academic Search

An equivalent circuit model in the rotor flux oriented frame is developed for the vector control of a linear induction motor (LIM) by adding the so called “end effect” to the rotary induction motor (RIM) model. We describe the effects of the end effect by introducing speed dependent scale factors to the magnetizing inductance and series resistance in the d-axis

Jeong-Hyoun Sung; Kwanghee Nam

1999-01-01

278

Robust speed identification for speed sensorless vector control of induction motors  

Microsoft Academic Search

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

Fang-Zheng Peng; Tadashi Fukao

1993-01-01

279

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

NASA Technical Reports Server (NTRS)

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.

Pagan, B.

1979-01-01

280

Vector and scalar control of a four switch three phase inverter  

Microsoft Academic Search

This paper investigates the PWM operation of a four switch three phase inverter (FSTPI), in the case of digital implementation. Different switching sequence strategies for vector control are described and a digital scaler method is also presented. The influence of different switching patterns on the output voltage symmetry, current waveform and switching frequency are examined. The results obtained by employing

C. B. Jacobina; E. R. C. da Silva; A. M. N. Lima; R. L. A. Ribeiro

1995-01-01

281

Robust vector control of induction motor without using stator and rotor circuit time constants  

Microsoft Academic Search

To solve the problem of performance degradation due to parameter variations in an indirect vector control of an induction motor, a novel and simple estimation method for the rotor circuit time constant is presented. The proposed method is based on regulating the energy stored in the magnetizing inductance, which can be calculated from the terminal voltages and currents. From theoretical

Kanokvate Tungpimolrut; Fang-Zheng Peng; Tadashi Fukao

1994-01-01

282

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

Microsoft Academic Search

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

C. C. Chan; HUAQIAN WANG

1990-01-01

283

TORQUE VECTOR CONTROL (TVC) OF AXIALLY-LAMINATED ANISOTROPIC (ALA) ROTOR RELUCTANCE SYNCHRONOUS MOTORS  

Microsoft Academic Search

Axially-laminated anisotropic (ALA) rotor reluctance synchronous motors (RSMs) have been proved recently capable of higher torque density, higher power factor and efficiency compared to their induction motor counterpart with the same stator. Vector current control systems have been proposed for such drives, based on maximum available torque constant current angle or minimum current for a given torque constant current angle

I. BOLDEA; Z. X. FU; S. A. NASAR

1991-01-01

284

Sensorless vector control of permanent magnet synchronous motor using adaptive identification  

Microsoft Academic Search

Vector controlled drives of a PMSM (permanent magnet synchronous motor) are proposed without position and speed sensor. The conventional pole position and speed sensors are eliminated by means of estimation using adaptive identification, for which stator voltages and currents are measured. To realize the proposed algorithm, a d-q current detecting method, which is independent of the rotor speed and position,

Min-Ho Park

1989-01-01

285

Speed-sensorless vector control of an induction motor using neural network speed estimation  

Microsoft Academic Search

In this paper, a novel speed estimation method of an induction motor using neural networks (NNs) is presented. The NN speed estimator is trained online by using the error backpropagation algorithm, and the training starts simultaneously with the induction motor working. The estimated speed is then fed back in the speed control loop, and the speed-sensorless vector drive is realized.

Seong-Hwan Kim; Tae-Sik Park; Ji-Yoon Yoo; Gwi-Tae Park

2001-01-01

286

Speed sensorless vector control of induction motor using extended Kalman filter  

Microsoft Academic Search

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

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

1994-01-01

287

Speed sensorless vector control of an induction motor using an extended Kalman filter  

Microsoft Academic Search

The vector control of an induction motor by speed estimation using an extended Kalman filter (EKF) is described. The rotor speed is regarded as a parameter, and the composite state is composed of the original state and the rotor speed. The EKF is employed to identify the speed of an induction motor and rotor magnetic flux based on the measured

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

1992-01-01

288

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

289

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

290

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

Microsoft Academic Search

Objective - I review the status of dichlorodiphenyltrichloroethane (DDT), used for disease vector control, along with current evidence on its benefits and risks in relation to the available alternatives. Data sources and extraction - Contemporary data on DDT use were largely obtained from questionnaires and reports. I also conducted a Scopus search to retrieve published articles. Data synthesis - DDT

Henk van den Berg

2009-01-01

291

Characterization of Spatial Repellent, Contact Irritant and Toxicant Chemical Actions of Standard Vector Control Compounds  

Technology Transfer Automated Retrieval System (TEKTRAN)

A previously described modular high-throughput screening system (HITTS) was used to characterize the spatial repellent, contact irritant and toxicant chemical actions of 14 compounds with a history of use in vector control. The response of F1-F4 Aedes aegypti to various concentrations of four organo...

292

Sleep-wake cycle in human African trypanosomiasis.  

PubMed

Sleeping sickness patients are classically described as sleepy by day and restless by night. Prior to this study, we had objectively confirmed this description by recording 24-h sleep patterns in a patient with human African trypanosomiasis. We report 24-h polysomnographic recordings (EEG, electrooculogram, electromyogram, electrocardiogram, and nasal, buccal, and thoracic respiratory traces) performed on two eight-channel electroencephalographs in eight patients with untreated sleeping sickness at an early stage of meningoencephalitis. As in our previously reported patient, there was no hypersomnia. The patients presented mainly a disorganization of the circadian alternation of sleeping and waking, with no or little alteration in the states of vigilance at this early stage of the disease. The disorganization was proportional to the degree of severity of the clinical symptoms. It may be due to an alteration in biological clock mechanisms. PMID:8389383

Buguet, A; Bert, J; Tapie, P; Tabaraud, F; Doua, F; Lonsdorfer, J; Bogui, P; Dumas, M

1993-04-01

293

Investigations on the control of bilharziasis vectors in Israel*  

PubMed Central

In spite of the arrival in Israel over the past decade of large numbers of immigrants infected with bilharziasis and although during that period there have been two sporadic outbreaks of the disease, there seems little immediate danger of bilharziasis spreading in the country. However, hydrographical, agricultural and economic conditions are subject to rapid changes in Israel and the present favourable situation may not be lasting. In anticipation, therefore, of possible outbreaks, laboratory experiments have been conducted to evaluate the efficacy in the control of Bulinus ova and adult snails and schistosome cercariae of a number of known molluscides and other substances. Although similar studies have been made in several other countries, it was felt advisable to repeat them under local hydrological conditions, particularly in view of the high carbonate content of the local waters. While most of the substances tested exert some molluscicidal action, only copper sulfate, sodium pentachlorophenate and common salt were found to be of practical value. PMID:14441019

Saliternik, Z.; Witenberg, G.

1959-01-01

294

Nanobody conjugated PLGA nanoparticles for active targeting of African Trypanosomiasis.  

PubMed

Targeted delivery of therapeutics is an alternative approach for the selective treatment of infectious diseases. The surface of African trypanosomes, the causative agents of African trypanosomiasis, is covered by a surface coat consisting of a single variant surface glycoprotein, termed VSG. This coat is recycled by endocytosis at a very high speed, making the trypanosome surface an excellent target for the delivery of trypanocidal drugs. Here, we report the design of a drug nanocarrier based on poly ethylen glycol (PEG) covalently attached (PEGylated) to poly(D,L-lactide-co-glycolide acid) (PLGA) to generate PEGylated PLGA nanoparticles. This nanocarrier was coupled to a single domain heavy chain antibody fragment (nanobody) that specifically recognizes the surface of the protozoan pathogen Trypanosoma brucei. Nanoparticles were loaded with pentamidine, the first-line drug for T. b. gambiense acute infection. An in vitro effectiveness assay showed a 7-fold decrease in the half-inhibitory concentration (IC50) of the formulation relative to free drug. Furthermore, in vivo therapy using a murine model of African trypanosomiasis demonstrated that the formulation cured all infected mice at a 10-fold lower dose than the minimal full curative dose of free pentamidine and 60% of mice at a 100-fold lower dose. This nanocarrier has been designed with components approved for use in humans and loaded with a drug that is currently in use to treat the disease. Moreover, this flexible nanobody-based system can be adapted to load any compound, opening a range of new potential therapies with application to other diseases. PMID:25445702

Arias, José L; Unciti-Broceta, Juan D; Maceira, José; Del Castillo, Teresa; Hernández-Quero, José; Magez, Stefan; Soriano, Miguel; García-Salcedo, José A

2015-01-10

295

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

PubMed Central

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

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

2014-01-01

296

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

NASA Astrophysics Data System (ADS)

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

Su, Xiao-hui; Xu, Shu-Ping

2013-03-01

297

Mosquito vector biology and control in Latin America--a 23rd symposium.  

PubMed

The 23rd Annual Latin American Symposium presented by the American Mosquito Control Association (AMCA) was held as part of the 79th Annual Meeting in Atlantic City, NJ, in February 2013. The principal objective, as for the previous 22 symposia, was to promote participation in the AMCA by vector control specialists, public health workers, and academicians from Latin America. This publication includes summaries of 49 presentations that were given orally in Spanish or presented as posters by participants from Colombia, Mexico, and the USA. Topics addressed in the symposium included: surveillance, ecology, chemical and biological control, and insecticide resistance associated with Aedes aegypti; surveillance and control of Anopheles vectors of malaria; and studies of dengue and West Nile viruses, Chagas disease, and Lutzomyia. PMID:24199500

Clark, Gary G; Fernandez-Salas, Ildefonso

2013-09-01

298

Spatial Predictions of Rhodesian Human African Trypanosomiasis (Sleeping Sickness) Prevalence in Kaberamaido and Dokolo, Two Newly Affected Districts of Uganda  

PubMed Central

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

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

2009-01-01

299

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

PubMed Central

Background There is a danger that mass drug administration campaigns may fail to maintain adequate treatment coverage to achieve lymphatic filariasis elimination. Hence, additional measures to suppress transmission might be needed to ensure the success of the Global Program for the Elimination of Lymphatic Filariasis. Discussion Vector control successfully eliminated lymphatic filariasis when implemented alone or with mass drug administration. Challenges to lymphatic filariasis elimination include uncertainty of the exact level and duration of microfilarial suppression required for elimination, the mobility of infected individuals, consistent non-participation of some infected individuals with mass drug administration, the possible development of anti-filarial drug resistance and treatment strategies in areas co-endemic with loasis. Integration of vector control with mass drug administration can address some of these challenges. The potential benefits of vector control would include: (1) the ability to suppress filariasis transmission without the need to identify all individual 'foci of infection'; (2) minimizing the risk of reestablishment of transmission from imported microfilaria positive individuals; and (3) decreasing the risk of dengue or malaria transmission where, respectively, Aedes or Anopheles are lymphatic filariasis vectors. Summary With adequate sustained treatment coverage, mass drug administration should meet the criteria for elimination of lymphatic filariasis. However, it may be difficult to sustain sufficiently high mass drug administration coverage to achieve lymphatic filariasis elimination in some areas, particularly, where Aedes species are the vectors. Since vector control was effective in controlling and even eliminating lymphatic filariasis transmission, integration of vector control with mass drug administration will ensure the sustainability of transmission suppression and thereby better ensure the success of national filariasis elimination programs. Although trials of some vector control interventions are needed, proven vector control strategies are ready for immediate integration with mass drug administration for many important vectors. Vector control is the only presently available additional lymphatic filariasis control measure with the potential for immediate implementation. PMID:16914040

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

2006-01-01

300

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

PubMed Central

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

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

2014-01-01

301

A new space-vector-based control method for UPS systems powering nonlinear and unbalanced loads  

Microsoft Academic Search

In this paper, a new real-time space-vector-based control strategy is presented for three-phase uninterruptible power supply systems powering nonlinear and unbalanced loads. The proposed control strategy generates the inverter reference and gating signals in closed loop and guarantees high-quality output voltages at the load terminals. The approach, which is implemented on a digital signal processor, adapts to a wide variation

U. Burup; Prasad N. Enjeti; Frede Blaabjerg

2001-01-01

302

Novel unity power factor circuits using zero-vector control for single-phase input systems  

Microsoft Academic Search

This paper proposes two novel circuits which realize a unity input power factor single-phase to three-phase converter with a motor load. The power supply is connected to the neutral point of the motor, and the three-phase inverter is controlled to act also as a virtual AC\\/DC power converter leg. This virtual leg is controlled by zero vectors of the three-phase

Jun-ichi Itoh; Kouetsu Fujita

2000-01-01

303

Vector control scheme of synchronous reluctance motor considering iron core loss  

Microsoft Academic Search

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

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

1998-01-01

304

Dynamic voltage restorer based on voltage-space-vector PWM control  

Microsoft Academic Search

A dynamic voltage restorer (DVR) based on the voltage-space-vector pulsewidth-modulation algorithm is presented. Phase-jump compensation is achieved using a software phase-locked loop and a lead-acid battery energy store. A battery-charging control technique using the DVR itself is also described. To validate the control of the DVR, a three-phase prototype with a power rating of 10 kVA has been successfully developed.

Changjiang Zhan; Vigna Kumaran Ramachandaramurthy; Atputharajah Arulampalam; Chris Fitzer; Stylianos Kromlidis; M. Bames; Nicholas Jenkins

2001-01-01

305

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

Microsoft Academic Search

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.

Ying-Yu Tzou; Hau-Jean Hsu

1997-01-01

306

Levitation forces control by current vector orientation for a bearingless motor with hybrid rotor structure  

Microsoft Academic Search

Because levitation forces in x-and y-direction for a bearingless motor with hybrid rotor structure are coupled, the decoupling method is needed to independently control the forces. This paper presents levitation forces control strategy through current vector orientation. By using transformation of two sets of winding phase currents in x-y frame to new variables in a d-q rotating reference frame, the

Baoguo Wang; Zheng Wang; Fengxiang Wang

2003-01-01

307

Vista/F-16 Multi-Axis Thrust Vectoring (MATV) control law design and evaluation  

NASA Technical Reports Server (NTRS)

For the Multi-Axis Thrust Vectoring (MATV) program, a new control law was developed using multi-axis thrust vectoring to augment the aircraft's aerodynamic control power to provide maneuverability above the normal F-16 angle of attack limit. The control law architecture was developed using Lockheed Fort Worth's offline and piloted simulation capabilities. The final flight control laws were used in flight test to demonstrate tactical benefits gained by using thrust vectoring in air-to-air combat. Differences between the simulator aerodynamics data base and the actual aircraft aerodynamics led to significantly different lateral-directional flying qualities during the flight test program than those identified during piloted simulation. A 'dial-a-gain' flight test control law update was performed in the middle of the flight test program. This approach allowed for inflight optimization of the aircraft's flying qualities. While this approach is not preferred over updating the simulator aerodynamic data base and then updating the control laws, the final selected gain set did provide adequate lateral-directional flying qualities over the MATV flight envelope. The resulting handling qualities and the departure resistance of the aircraft allowed the 422nd_squadron pilots to focus entirely on evaluating the aircraft's tactical utility.

Zwerneman, W. D.; Eller, B. G.

1994-01-01

308

Legal aspects of public health: difficulties in controlling vector-borne and zoonotic diseases in Brazil.  

PubMed

In recent years, vector-borne and zoonotic diseases have become a major challenge for public health. Dengue fever and leptospirosis are the most important communicable diseases in Brazil based on their prevalence and the healthy life years lost from disability. The primary strategy for preventing human exposure to these diseases is effective insect and rodent control in and around the home. However, health authorities have difficulties in controlling vector-borne and zoonotic diseases because residents often refuse access to their homes. This study discusses aspects related to the activities performed by Brazilian health authorities to combat vector-borne and zoonotic diseases, particularly difficulties in relation to the legal aspect, which often impede the quick and effective actions of these professionals. How might it be possible to reconcile the need to preserve public health and the rule on the inviolability of the home, especially in the case of abandoned properties or illegal residents and the refusal of residents to allow the health authority access? Do residents have the right to hinder the performance of health workers even in the face of a significant and visible focus of disease transmission? This paper argues that a comprehensive legal plan aimed at the control of invasive vector-borne and zoonotic diseases including synanthropic animals of public health importance should be considered. In addition, this paper aims to bridge the gap between lawyers and public health professionals and to facilitate communication between them. PMID:25051187

Mendes, Marcílio S; de Moraes, Josué

2014-11-01

309

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

PubMed

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

van den Berg, Henk

2011-02-01

310

Vector tick populations and Lyme disease. A summary of control strategies.  

PubMed

Although many aspects of Lyme disease have been intensely studied for over a decade, little research has been directed toward control of the principal tick vector, Ixodes dammini. Ecological and epidemiological investigations have provided not only an ample understanding of tick biology and behavior, they have also identified the types of areas at risk for disease transmission. The advantages and limitations of previous attempts to control I. dammini by host reduction, habitat modification, and acaricide applications have been discussed in relation to overall control strategies for high-risk areas, and an integrated approach to control proposed. PMID:3190092

Schulze, T L; Parkin, W E; Bosler, E M

1988-01-01

311

Design development of the Apollo command and service module thrust vector attitude control systems  

NASA Technical Reports Server (NTRS)

Development of the Apollo thrust vector control digital autopilot (TVC DAP) was summarized. This is the control system that provided pitch and yaw attitude control during velocity change maneuvers using the main rocket engine on the Apollo service module. A list of ten primary functional requirements for this control system are presented, each being subordinate to a more general requirement appearing earlier on the list. Development process functions were then identified and the essential information flow paths were explored. This provided some visibility into the particular NASA/contractor interface, as well as relationships between the many individual activities.

Peters, W. H.

1978-01-01

312

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

PubMed

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 the 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 that the proposed program is generally applicable to vector-borne disease control. PMID:24794113

Powell, Jeffrey R; Tabachnick, Walter J

2014-06-01

313

Control of many electron states in semiconductor quantum dots by non-Abelian vector potentials  

E-print Network

Adiabatic time evolution of degenerate eigenstates of a quantum system provides a means for controlling electronic states since mixing between degenerate levels generates a matrix Berry phase. In the presence of spin-orbit coupling in n-type semiconductor quantum dots the electron Hamiltonian is invariant under time reversal operation and the many body groundstate may be doubly degenerate. This double degeneracy can generate non-Abelian vector potentials when odd number of electrons are present. We find that the antisymmetry of many electron wavefunction has no effect on the matrix Berry phase. We have derived equations that allow one to investigate the effect of electron correlations by expressing the non-Abelian vector potentials for many electron system in terms of single electron non-Abelian vector potentials.

S. -R. Eric Yang

2007-06-07

314

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

PubMed Central

Emerging vector-borne diseases represent an important issue for global health. Many vector-borne pathogens have appeared in new regions in the past two decades, and many endemic diseases have increased in incidence. Although introductions and local emergence are frequently considered distinct processes, many emerging endemic pathogens are in fact invading at a local scale coincident with habitat change. We highlight key differences in the dynamics and disease burden that result from increased pathogen transmission following habitat change compared with the introduction of pathogens to new regions. Truly in situ emergence is commonly driven by changes in human factors as much as by enhanced enzootic cycles whereas pathogen invasion results from anthropogenic trade and travel and suitable conditions for a pathogen, including hosts, vectors, and climate. Once established, ecological factors related to vector characteristics shape the evolutionary selective pressure on pathogens that may result in increased use of humans as transmission hosts. We describe challenges inherent in the control of vector-borne zoonotic diseases and some emerging non-traditional strategies that may be more effective in the long term. PMID:23200503

Kilpatrick, A. Marm; Randolph, Sarah E.

2013-01-01

315

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

NASA Astrophysics Data System (ADS)

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

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

2008-01-01

316

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

PubMed Central

The rational design of interventions is critical to controlling communicable diseases, especially in urban environments. In the case of the Chagas disease vector Triatoma infestans, successful control is stymied by the return of the insect after the effectiveness of the insecticide wanes. Here, we adapt a genetic algorithm, originally developed for the travelling salesman problem, to improve the spatio-temporal design of insecticide campaigns against T. infestans, in a complex urban environment. We find a strategy that reduces the expected instances of vector return 34-fold compared with the current strategy of sequential insecticide application to spatially contiguous communities. The relative success of alternative control strategies depends upon the duration of the effectiveness of the insecticide, and it shows chaotic fluctuations in response to unforeseen delays in a control campaign. We use simplified models to analyse the outcomes of qualitatively different spatio-temporal strategies. Our results provide a detailed procedure to improve control efforts for an urban Chagas disease vector, as well as general guidelines for improving the design of interventions against other disease agents in complex environments. PMID:20061346

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

2010-01-01

317

An adaptive supervisory sliding fuzzy cerebellar model articulation controller for sensorless vector-controlled induction motor drive systems.  

PubMed

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

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

2015-01-01

318

Computational dynamic programming for stochastic optimal control on a vector multiprocessor  

SciTech Connect

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

Hanson, F.B.

1988-06-01

319

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

PubMed

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

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

2014-03-01

320

[New vector control measures implemented between 2005 and 2011 on Reunion Island: lessons learned from chikungunya epidemic].  

PubMed

A major chikungunya outbreak concerned 38% of people living in Reunion Island in 2005-2006. Chikungunya is an arthropod-born-virus disease conveyed by mosquitoes called Aedes albopictus. The health agency in Indian Ocean is responsible for vector control. Previously, in the early 40s, vector control concerned only malaria prophylaxis in La Réunion. Then, during the chikungunya outbreak, a new vector control team was installed and learned from this epidemic. The lessons drawn from chikungunya outbreak in La Réunion are about global executive management and organization linked the local partners and population. The lessons also concern technical topics such as the need of scientific research about vectors and vector-control methods. Finally, the regional cooperation in Indian Ocean (Réunion, Maurice, Seychelles, Comoros, Madagascar) has to be developed to share epidemiologic and entomologic data in order to prevent new chikungunya or dengue outbreak. PMID:22693927

Bâville, M; Dehecq, J S; Reilhes, O; Margueron, T; Polycarpe, D; Filleul, L

2012-03-01

321

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

PubMed Central

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

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

2014-01-01

322

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

Microsoft Academic Search

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

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

1990-01-01

323

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

Microsoft Academic Search

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

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

1991-01-01

324

Sliding-mode MRAS speed estimators for sensorless vector control of induction Machine  

Microsoft Academic Search

This paper presents two novel sliding mode (SM) model reference adaptive system (MRAS) observers for speed estimation in a sensorless-vector-controlled induction-machine drive. Both methods use the flux estimated by the voltage model observer as the reference and construct SM flux observers that allow speed estimation. Stability and dynamics of the two proposed SM flux observers are discussed. The observers are

Mihai Comanescu; Longya Xu

2006-01-01

325

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

PubMed Central

Background Control and prevention of Chagas disease rely mostly on residual spraying of insecticides. In Argentina, vector control shifted from a vertical to a fully horizontal strategy based on community participation between 1992 and 2004. The effects of such strategy on Triatoma infestans, the main domestic vector, and on disease transmission have not been assessed. Methods and Findings Based on retrospective (1993–2004) records from the Argentinean Ministry of Health for the Moreno Department, Northwestern Argentina, we performed a cost-effectiveness (CE) analysis and compared the observed CE of the fully horizontal vector control strategy with the expected CE for a vertical or a mixed (i.e., vertical attack phase followed by horizontal surveillance) strategy. Total direct costs (in 2004 US$) of the horizontal and mixed strategies were, respectively, 3.3 and 1.7 times lower than the costs of the vertical strategy, due to reductions in personnel costs. The estimated CE ratios for the vertical, mixed and horizontal strategies were US$132, US$82 and US$45 per averted human case, respectively. When per diems were excluded from the costs (i.e., simulating the decentralization of control activities), the CE of vertical, mixed and horizontal strategies was reduced to US$60, US$42 and US$32 per averted case, respectively. Conclusions and Significance The mixed strategy would have averted between 1.6 and 4.0 times more human cases than the fully horizontal strategy, and would have been the most cost-effective option to interrupt parasite transmission in the Department. In rural and dispersed areas where waning vertical vector programs cannot accomplish full insecticide coverage, alternative strategies need to be developed. If properly implemented, community participation represents not only the most appealing but also the most cost-effective alternative to accomplish such objectives. PMID:19156190

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

2009-01-01

326

Adaptive full order observer based stable speed sensorless scheme for vector controlled induction motor drives  

Microsoft Academic Search

The full-order Luenberger flux observer (FOLO) combined with adaptive techniques is the most widely used method for sensorless induction machine (IM) vector controlled drives. However, IM model-based sensorless schemes have an inherently unstable region under regenerating conditions. Additionally, the stator resistance is also required at low speeds, which leads to a complicated multiple-input multiple-output (MIMO) system. In this paper, the

Iban Vicente; Aitor Endemaño; Xabier Garin; Martin Brown

2009-01-01

327

User's guide for vectorized code EQUIL for calculating equilibrium chemistry on Control Data STAR-100 computer  

NASA Technical Reports Server (NTRS)

A vectorized code, EQUIL, was developed for calculating the equilibrium chemistry of a reacting gas mixture on the Control Data STAR-100 computer. The code provides species mole fractions, mass fractions, and thermodynamic and transport properties of the mixture for given temperature, pressure, and elemental mass fractions. The code is set up for the electrons H, He, C, O, N system of elements. In all, 24 chemical species are included.

Kumar, A.; Graves, R. A., Jr.; Weilmuenster, K. J.

1980-01-01

328

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

PubMed Central

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

2014-01-01

329

In silico models for predicting vector control chemicals targeting Aedes aegypti  

PubMed Central

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

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

2014-01-01

330

Mapping Neglected Swimming Pools from Satellite Data for Urban Vector Control  

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

331

Noise-induced hearing loss and associated factors among vector control workers in a Malaysian state.  

PubMed

This study aims to determine the prevalence and associated factors of noise-induced hearing loss (NIHL) among vector control workers in the state of Negeri Sembilan, Malaysia. This was an analytical cross-sectional study conducted on 181 vector control workers who were working in district health offices in a state in Malaysia. Data were collected using a self-administered questionnaire and audiometry. Prevalence of NIHL was 26% among this group of workers. NIHL was significantly associated with the age-group of 40 years and older, length of service of 10 or more years, current occupational noise exposure, listening to loud music, history of firearms use, and history of mumps/measles infection. Following logistic regression, age of more than 40 years and noise exposure in current occupation were associated with NIHL with an odds ratio of 3.45 (95% confidence interval = 1.68-7.07) and 6.87 (95% confidence interval = 1.54-30.69), respectively, among this group of vector control workers. PMID:22548779

Masilamani, Retneswari; Rasib, Abdul; Darus, Azlan; Ting, Anselm Su

2014-11-01

332

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

PubMed

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

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

2014-01-01

333

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

E-print Network

- 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 validate the ability of the proposed method to trace the contact point position and to estimate force

Tachi, Susumu

334

VECTOR CONTROL, PEST MANAGEMENT, RESISTANCE, REPELLENTS Effect of Prescribed Fire for Tick Control in California Chaparral  

E-print Network

, Dermacentor occi- dentalis Marx. I. pacificus is an important vector of Borrelia burgdorferi sensu stricto in the treatment sites postburn. This species is known to be a reservoir of the agents of Lyme disease, Borrelia burgdorferi sensu stricto Johnson, Schmid, Hyde, Steigerwalt & Brenner, and human gran- ulocytic anaplasmosis

Stephens, Scott L.

335

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

PubMed Central

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

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

2014-01-01

336

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

PubMed Central

Background The effect of integrating vector larval intervention on malaria transmission is unknown when insecticide-treated bed-net (ITN) coverage is very high, and the optimal indicator for intervention evaluation needs to be determined when transmission is low. Methods A post hoc assignment of intervention-control cluster design was used to assess the added effect of both indoor residual spraying (IRS) and Bacillus-based larvicides (Bti) in addition to ITN in the western Kenyan highlands in 2010 and 2011. Cross-sectional, mass parasite screenings, adult vector populations, and cohort of active case surveillance (ACS) were conducted before and after the intervention in three study sites with two- to three-paired intervention-control clusters at each site each year. The effect of larviciding, IRS, ITNs and other determinants of malaria risk was assessed by means of mixed estimating methods. Results Average ITN coverage increased from 41% in 2010 to 92% in 2011 in the study sites. IRS intervention had significant added impact on reducing vector density in 2010 but the impact was modest in 2011. The effect of IRS on reducing parasite prevalence was significant in 2011 but was seasonal specific in 2010. ITN was significantly associated with parasite densities in 2010 but IRS application was significantly correlated with reduced gametocyte density in 2011. IRS application reduced about half of the clinical malaria cases in 2010 and about one-third in 2011 compare to non-intervention areas. Conclusion Compared with a similar study conducted in 2005, the efficacy of the current integrated vector control with ITN, IRS, and Bti reduced three- to five-fold despite high ITN coverage, reflecting a modest added impact on malaria transmission. Additional strategies need to be developed to further reduce malaria transmission. PMID:23870708

2013-01-01

337

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

PubMed Central

Background Long Lasting Insecticidal Nets (LLIN) and Indoor Residual Spraying (IRS) have both proven to be effective malaria vector control strategies in Africa and the new technology of insecticide treated durable wall lining (DL) is being evaluated. Sustaining these interventions at high coverage levels is logistically challenging and, furthermore, the increase in insecticide resistance in African malaria vectors may reduce the efficacy of these chemical based interventions. Monitoring of vector populations and evaluation of the efficacy of insecticide based control approaches should be integral components of malaria control programmes. This study reports on entomological survey conducted in 2011 in Bomi County, Liberia. Methods Anopheles gambiae larvae were collected from four sites in Bomi, Liberia, and reared in a field insectary. Two to five days old female adult An gambiae s.l. were tested using WHO tube (n?=?2027) and cone (n?=?580) bioassays in houses treated with DL or IRS. A sample of mosquitoes (n?=?169) were identified to species/molecular form and screened for the presence of knock down resistance (kdr) alleles associated with pyrethroid resistance. Results Anopheles gambiae s.l tested were resistant to deltamethrin but fully susceptible to bendiocarb and fenithrothion. The corrected mortality of local mosquitoes exposed to houses treated with deltamethrin either via IRS or DL was 12% and 59% respectively, suggesting that resistance may affect the efficacy of these interventions. The presence of pyrethroid resistance was associated with a high frequency of the 1014F kdr allele (90.5%) although this mutation alone cannot explain the resistance levels observed. Conclusion High prevalence of resistance to deltamethrin in Bomi County may reduce the efficacy of malaria strategies relying on this class of insecticide. The findings highlight the urgent need to expand and sustain monitoring of insecticide resistance in Liberian malaria vectors, evaluate the effectiveness of existing interventions and develop appropriate resistance management strategies. PMID:23028724

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

2012-01-01

338

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

PubMed Central

Objective I review the status of dichlorodiphenyltrichloroethane (DDT), used for disease vector control, along with current evidence on its benefits and risks in relation to the available alternatives. Data sources and extraction Contemporary data on DDT use were largely obtained from questionnaires and reports. I also conducted a Scopus search to retrieve published articles. Data synthesis DDT has been recommended as part of the arsenal of insecticides available for indoor residual spraying until suitable alternatives are available. Approximately 14 countries use DDT for disease control, and several countries are preparing to reintroduce DDT. The effectiveness of DDT depends on local settings and merits close consideration in relation to the alternatives. Concerns about the continued use of DDT are fueled by recent reports of high levels of human exposure associated with indoor spraying amid accumulating evidence on chronic health effects. There are signs that more malaria vectors are becoming resistant to the toxic action of DDT, and that resistance is spreading to new countries. A comprehensive cost assessment of DDT versus its alternatives that takes side effects into account is missing. Effective chemical methods are available as immediate alternatives to DDT, but the choice of insecticide class is limited, and in certain areas the development of resistance is undermining the efficacy of insecticidal tools. New insecticides are not expected in the short term. Nonchemical methods are potentially important, but their effectiveness at program level needs urgent study. Conclusions To reduce reliance on DDT, support is needed for integrated and multipartner strategies of vector control and for the continued development of new technologies. Integrated vector management provides a framework for developing and implementing effective technologies and strategies as sustainable alternatives to reliance on DDT. PMID:20049114

van den Berg, Henk

2009-01-01

339

Detection and characterization of autoantibodies directed against neurofilament proteins in human African trypanosomiasis.  

PubMed

In serum and in cerebrospinal fluid (CSF) from patients with human African trypanosomiasis (HAT) with central nervous system involvement, we detected autoantibodies directed to some proteins from these tissues. The characterization of antigenic proteins by Western blotting showed that the antibodies recognized the 200-kD and 160-kD proteins of neurofilament (NF). Serum anti-NF antibodies were more frequent in HAT patients than in control subjects (86% versus 24%; P < 10[-9]) and they belonged predominantly to the IgM class (anti-NF IgM = 86% versus anti-NF IgG = 4%; P < 10[-9]) in the patients with stage II (central nervous system involvement) HAT. The CSF antibodies to NF were IgM in 88% (22 of 25) of the cases and IgG in 32% (8 of 25) of the cases. Epitopes shared by NF and trypanosomes were detected by indirect immunofluorescence and this was confirmed by the disappearance of anti-NF reactivity after adsorption with trypanosome antigens (Trypanosoma brucei brucei or T. b. gambiense). Anti-NF antibodies were undetectable in the CSF from stage I HAT patients. PMID:9242309

Ayed, Z; Brindel, I; Bouteille, B; Van Meirvenne, N; Doua, F; Houinato, D; Dumas, M; Jauberteau, M O

1997-07-01

340

Hepatic microsomal alterations during chronic trypanosomiasis in the field vole, Microtus montanus.  

PubMed

The field vole, Microtus montanus, was used as a model system to evaluate the chronic effects of infection by Trypanosoma brucei gambiense on hepatic mixed-function oxidase activity. At day 28 post inoculation there was a 97% increase in liver wet weight per g body weight. A portion of the increase (21%) was accounted for by tissue edema which occurred after day 14 of infection. Total hepatic cytochrome P-450 content and related total tissue mixed-function oxidase activities were decreased to about 60% of control levels at day 28 post inoculation. The decrease in total tissue mixed-function oxidase activity was partly due to a small decrease in microsomal protein per cell, and partly to a large decrease in cytochrome P-450 concentration in the endoplasmic reticulum. Although the decrease in total liver monooxygenase activity in several substrates roughly paralleled the loss in cytochrome P-450 content, several other microsomal enzyme markers not related to cytochrome P-450 monooxygenation were elevated in proportion to total liver microsomal protein content. The results suggest that in M. montanus during trypanosomiasis, there is proliferation of hepatic cells with normal content of endoplasmic reticulum. Furthermore, there appears to be selective toxicity for hepatic cytochrome P-450 and related monooxygenase activities. This may compromise the animals' ability to metabolize and dispose of other drugs to which the animal may be exposed in the course of infection. PMID:7050701

Shertzer, H G; Hall, J E; Seed, J R

1982-07-01

341

The digital autopilot for thrust vector control of the Shuttle Orbital maneuvering system  

NASA Technical Reports Server (NTRS)

This paper describes the requirements for and the design, development and performance of the digital autopilots (DAPs) for thrust vector control, utilizing the orbital maneuvering system (OMS) of the Space Shuttle Orbiter. The hardware and software requirements which caused the design to assume its current form are described. Also, the design synthesis, which considered rigid body stability margins, bending and slosh stabilization, guidance loop compensation, off-nominal performance and hardware and software limitations is presented. The performance of the OMS control system is summarized utilizing flight data from the first three Space Transportation System (STS) flights.

Penchuk, A.; Croopnick, S.

1982-01-01

342

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

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

343

A stator-flux-based vector control method for parallel-connected multiple induction motors fed by a single inverter  

Microsoft Academic Search

This paper presents a novel vector control method for a parallel-connected multiple motor drive system. The proposed control method is based on the stator-flux, and is capable of accurate and responsive torque control even if there are the rotor velocity differences among the motors. To confirm the validity of the proposed control method, the authors compare a simulation result of

Y. Matsumoto; C. Osawa; T. Mizukami; S. Ozaki

1998-01-01

344

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

PubMed

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

Soni, Namita; Prakash, Soam

2014-11-01

345

The role of vector control in stopping the transmission of malaria: threats and opportunities  

PubMed Central

Malaria control, and that of other insect borne diseases such as dengue, is heavily dependent on our ability to control the mosquito populations that transmit these diseases. The major push over the last decade to reduce the global burden of malaria has been driven by the distribution of pyrethroid insecticide-treated bednets and an increase in coverage of indoor residual spraying (IRS). This has reduced malaria deaths by a third. Progress towards the goal of reducing this further is threatened by lack of funding and the selection of drug and insecticide resistance. When malaria control was initially scaled up, there was little pyrethroid resistance in the major vectors, today there is no country in Africa where the vectors remain fully susceptible to pyrethroids. The first pyrethroid resistance mechanisms to be selected produced low-level resistance which had little or no operational significance. More recently, metabolically based resistance has been selected, primarily in West Africa, which in some mosquito populations produces more than 1000-fold resistance. As this spreads the effectiveness of pyrethroid-based bednets and IRS will be compromised. New public health insecticides are not readily available. The pipeline of agrochemical insecticides that can be re-purposed for public health dried up 30 years ago when the target product profile for agricultural insecticides shifted from broad spectrum, stable, contact-acting insecticides to narrow spectrum stomach poisons that could be delivered through the plant. A public–private partnership, the Innovative Vector Control Consortium, was established in 2005 to stimulate the development of new public health pesticides. Nine potential new classes of chemistry are in the pipeline, with the intention of developing three into new insecticides. While this has been successfully achieved, it will still take 6–9 years for new insecticides to reach the market. Careful management of the resistance situation in the interim will be needed if current gains in malaria control are not to be reversed. PMID:24821917

Hemingway, Janet

2014-01-01

346

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

PubMed

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

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

2011-01-01

347

Precision Vector Control of a Superconducting RF Cavity driven by an Injection Locked Magnetron  

E-print Network

The technique presented in this paper enables the regulation of both radio frequency amplitude and phase in narrow band devices such as a Superconducting RF (SRF) cavity driven by constant power output devices i.e. magnetrons. The ability to use low cost high efficiency magnetrons for accelerator RF power systems, with tight vector regulation, presents a substantial cost savings in both construction and operating costs compared to current RF power system technology. An operating CW system at 2.45 GHz has been experimentally developed. Vector control of an injection locked magnetron has been extensively tested and characterized with a SRF cavity as the load. Amplitude dynamic range of 30 dB, amplitude stability of 0.3% r.m.s, and phase stability of 0.26 degrees r.m.s. has been demonstrated.

Brian Chase; Ralph Pasquinelli; Ed Cullerton; Philip Varghese

2014-11-21

348

A computational study of thrust vectoring control using dual throat nozzle  

NASA Astrophysics Data System (ADS)

Dual throat nozzle (DTN) is fast becoming a popular technique for thrust vectoring. The DTN is designed with two throats, an upstream minimum and a downstream minimum at the nozzle exit, with a cavity in between the upstream throat and exit. In the present study, a computational work has been carried out to analyze the performance of a dual throat nozzle at various mass flow rates of secondary flow and nozzle pressure ratios (NPR). Two-dimensional, steady, compressible Navier-Stokes equations were solved using a fully implicit finite volume scheme. The present computational results were validated with available experimental data. Based on the present results, the control effectiveness of thrust-vectoring is discussed in terms of the thrust coefficient and the coefficient of discharge.

Shin, Choon Sik; Kim, Heuy Dong; Setoguchi, Toshiaki; Matsuo, Shigeru

2010-12-01

349

Precision vector control of a superconducting RF cavity driven by an injection locked magnetron  

NASA Astrophysics Data System (ADS)

The technique presented in this paper enables the regulation of both radio frequency amplitude and phase in narrow band devices such as a Superconducting RF (SRF) cavity driven by constant power output devices i.e. magnetrons [1]. The ability to use low cost high efficiency magnetrons for accelerator RF power systems, with tight vector regulation, presents a substantial cost savings in both construction and operating costs - compared to current RF power system technology. An operating CW system at 2.45 GHz has been experimentally developed. Vector control of an injection locked magnetron has been extensively tested and characterized with a SRF cavity as the load. Amplitude dynamic range of 30 dB, amplitude stability of 0.3% r.m.s, and phase stability of 0.26 degrees r.m.s. has been demonstrated.

Chase, B.; Pasquinelli, R.; Cullerton, E.; Varghese, P.

2015-03-01

350

Precision Vector Control of a Superconducting RF Cavity driven by an Injection Locked Magnetron  

E-print Network

The technique presented in this paper enables the regulation of both radio frequency amplitude and phase in narrow band devices such as a Superconducting RF (SRF) cavity driven by constant power output devices i.e. magnetrons. The ability to use low cost high efficiency magnetrons for accelerator RF power systems, with tight vector regulation, presents a substantial cost savings in both construction and operating costs compared to current RF power system technology. An operating CW system at 2.45 GHz has been experimentally developed. Vector control of an injection locked magnetron has been extensively tested and characterized with a SRF cavity as the load. Amplitude dynamic range of 30 dB, amplitude stability of 0.3% r.m.s, and phase stability of 0.26 degrees r.m.s. has been demonstrated.

Chase, Brian; Cullerton, Ed; Varghese, Philip

2015-01-01

351

Operational efficiency and sustainability of vector control of malaria and dengue: descriptive case studies from the Philippines  

PubMed Central

Background Analysis is lacking on the management of vector control systems in disease-endemic countries with respect to the efficiency and sustainability of operations. Methods Three locations were selected, at the scale of province, municipality and barangay (i.e. village). Data on disease incidence, programme activities, and programme management were collected on-site through meetings and focus group discussions. Results Adaptation of disease control strategies to the epidemiological situation per barangay, through micro-stratification, brings gains in efficiency, but should be accompanied by further capacity building on local situational analysis for better selection and targeting of vector control interventions within the barangay. An integrated approach to vector control, aiming to improve the rational use of resources, was evident with a multi-disease strategy for detection and response, and by the use of combinations of vector control methods. Collaboration within the health sector was apparent from the involvement of barangay health workers, re-orientation of job descriptions and the creation of a disease surveillance unit. The engagement of barangay leaders and use of existing community structures helped mobilize local resources and voluntary services for vector control. In one location, local authorities and the community were involved in the planning, implementation and evaluation of malaria control, which triggered local programme ownership. Conclusions Strategies that contributed to an improved efficiency and sustainability of vector control operations were: micro-stratification, integration of vector control within the health sector, a multi-disease approach, involvement of local authorities, and empowerment of communities. Capacity building on situational analysis and vector surveillance should be addressed through national policy and guidelines. PMID:22873707

2012-01-01

352

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

PubMed Central

Background High coverage of personal protection measures that kill mosquitoes dramatically reduce malaria transmission where vector populations depend upon human blood. However, most primary malaria vectors outside of sub-Saharan Africa can be classified as “very zoophagic,” meaning they feed occasionally (<10% of blood meals) upon humans, so personal protection interventions have negligible impact upon their survival. Methods and Findings We extended a published malaria transmission model to examine the relationship between transmission, control, and the baseline proportion of bloodmeals obtained from humans (human blood index). The lower limit of the human blood index enables derivation of simplified models for zoophagic vectors that (1) Rely on only three field-measurable parameters. (2) Predict immediate and delayed (with and without assuming reduced human infectivity, respectively) impacts of personal protection measures upon transmission. (3) Illustrate how appreciable indirect communal-level protection for non-users can be accrued through direct personal protection of users. (4) Suggest the coverage and efficacy thresholds required to attain epidemiological impact. The findings suggest that immediate, indirect, community-wide protection of users and non-users alike may linearly relate to the efficacy of a user’s direct personal protection, regardless of whether that is achieved by killing or repelling mosquitoes. High protective coverage and efficacy (?80%) are important to achieve epidemiologically meaningful impact. Non-users are indirectly protected because the two most common species of human malaria are strict anthroponoses. Therefore, the small proportion of mosquitoes that are killed or diverted while attacking humans can represent a large proportion of those actually transmitting malaria. Conclusions Simplified models of malaria transmission by very zoophagic vectors may be used by control practitioners to predict intervention impact interventions using three field-measurable parameters; the proportion of human exposure to mosquitoes occurring when an intervention can be practically used, its protective efficacy when used, and the proportion of people using it. PMID:22701527

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

2012-01-01

353

Robust Hotelling T2 control chart using reweighted minimum vector variance estimators  

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

354

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

NASA Technical Reports Server (NTRS)

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.

Stoneking, Eric; Lebsock, Ken

2008-01-01

355

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

NASA Technical Reports Server (NTRS)

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.

Stoneking, Eric; Lebsock, Ken

2008-01-01

356

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

Microsoft Academic Search

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

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

2005-01-01

357

Vector population manipulation for control of arboviruses--a novel prospect for India.  

PubMed

India, the seventh largest country in the world, has diverse geographical and climatic regions with vast rural and peri-urban areas. Many are experiencing an escalation in the spread and intensity of numerous human diseases transmitted by insects. Classically, the management of these vector-borne diseases is underpinned by either chemical insecticides and/or environmental management targeted at the vector. However, these methods or their present implementation do not offer acceptable levels of control, and more effective and sustainable options are now available. Genetic strategies for the prevention of arbovirus transmission are most advanced for dengue and chikungunya, targeting their primary vector, Aedes aegypti. The national burden in terms of morbidity and mortality as a direct consequence of dengue virus in India is considered to be the largest worldwide, over 4 times that of any other country. Presently, new genetic technologies are undergoing field evaluation of their biosafety and efficacy in several countries. This paper discusses the merits of these approaches and argues for fair and transparent appraisal in India as a matter of urgency. Identification of any associated risks and their appropriate mitigation are fundamental to that process. PMID:24254373

Niranjan Reddy, Bp; Gupta, Bhavna; Rao, B Prasad

2014-04-01

358

[The distribution of sleep and wakefulness in human African trypanosomiasis].  

PubMed

Last century, patients with human African trypanosomiasis were described as sleepy by day and restless by night, and physicians referred to this condition as sleeping sickness. Such a description could have evoked a disturbance of circadian rhythms. However, it is only in 1989 that the first 24-hour recording was performed by our team in Niamey (Niger) in a patient with sleeping sickness. The patient was a Niger-born farm worker who had contracted the disease near Gagnoa (Côte d'Ivoire). Polysomnographic recordings (electroencephalogram, EEG, electrooculogram, electromyogram, electrocardiogram, buccal and nasal airflow, and chest respiratory movements) showed a disappearance of the circadian distribution of sleep and wakefulness, which tended to occur evenly throughout day and night, with a sleep-wake alternation of approximately 80 minutes. Two investigations were conducted thereafter. The first one was done at Daloa (Côte d'Ivoire) in 8 patients who were recorded during two 24-hour periods, with and without hourly blood samples; the second at Brazzaville (Congo) in 10 patients recorded for 24 hours before and after treatment with melarsoprol. All patients were at the stage of early meningoencephalitis. At Daloa, polysomnographic recordings were taken on two 8-channel EEG machines (Alvar Minihuit, and T3-ECEM), as well as on a portable Oxford Medilog 9000 system from the same electrodes. Sleep and wake structure was altered in the most severely sick patient, the EEG trace being loaded with slow waves. Stages 1 and 2, and stages 3 and 4 could not be distinguished from one another. In the other patients, all sleep stages were easily scored. No difference was seen between recordings, regarding blood collection.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7496201

Buguet, A; Bert, J; Tapie, P; Bogui, P; Doua, F; Mouanga, G; Stanghellini, A; Sarda, J; Tabaraud, F; Gati, R

1994-01-01

359

A vector control and data acquisition system for the multicavity LLRF system for cryomodule1 at Fermilab  

E-print Network

A LLRF control and data acquisition system for the 8-cavity cryomodule1 at the ILCTA has been implemented using three 33-channel ADC boards in a VXI mainframe. One card each is dedicated to the cavity probes for vector control, forward power and reverse power measurements. The system is scalable to 24 cavities or more with the commissioning of cryomodules 2 and 3 without additional hardware. The signal processing and vector control of the cavities is implemented in an FPGA and a high speed data acquisition system with up to 100 channels which stores data in external SDRAM memory. The system supports both pulsed and CW modes with a pulse rate of 5 Hz. Acquired data is transferred between pulses to auxiliary systems such as the piezo controller through the VXI slot0 controller. The performance of the vector control system is evaluated and the design of the system is described.

Varghese, P; Barnes, B; Branlard, J; Cullerton, E; Joireman, P; Tupikov, V

2012-01-01

360

Advances in biological control in relation to vectors of human diseases  

PubMed Central

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

Weiser, J.

1963-01-01

361

Anticipatory Monitoring and Control of Complex Systems using a Fuzzy based Fusion of Support Vector Regressors  

SciTech Connect

This paper places itself in the realm of anticipatory systems and envisions monitoring and control methods being capable of making predictions over system critical parameters. Anticipatory systems allow intelligent control of complex systems by predicting their future state. In the current work, an intelligent model aimed at implementing anticipatory monitoring and control in energy industry is presented and tested. More particularly, a set of support vector regressors (SVRs) are trained using both historical and observed data. The trained SVRs are used to predict the future value of the system based on current operational system parameter. The predicted values are then inputted to a fuzzy logic based module where the values are fused to obtain a single value, i.e., final system output prediction. The methodology is tested on real turbine degradation datasets. The outcome of the approach presented in this paper highlights the superiority over single support vector regressors. In addition, it is shown that appropriate selection of fuzzy sets and fuzzy rules plays an important role in improving system performance.

Miltiadis Alamaniotis; Vivek Agarwal

2014-10-01

362

Independent Orbiter Assessment (IOA): Analysis of the ascent thrust vector control actuator subsystem  

NASA Technical Reports Server (NTRS)

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results for the Ascent Thrust Vector Control (ATVC) Actuator hardware are documented. The function of the Ascent Thrust Vector Control Actuators (ATVC) is to gimbal the main engines to provide for attitude and flight path control during ascent. During first stage flight, the SRB nozzles provide nearly all the steering. After SRB separation, the Orbiter is steered by gimbaling of its main engines. There are six electrohydraulic servoactuators, one pitch and one yaw for each of the three main engines. Each servoactuator is composed of four electrohydraulic servovalve assemblies, one second stage power spool valve assembly, one primary piston assembly and a switching valve. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. Critical failures resulting in loss of ATVC were mainly due to loss of hydraulic fluid, fluid contamination and mechanical failures.

Wilson, R. E.; Riccio, J. R.

1986-01-01

363

Solid rocket booster thrust vector control V-2 off-nominal testing  

NASA Technical Reports Server (NTRS)

The results of the V-2 off nominal test sequence performed on the space shuttle solid rocket booster thrust vector control (SRB TVC) system are reported. The TVC subsystem was subjected to 19 off nominal test conditions. The test sequence consisted of: 8 burp starts, 30 hot firings, 14 GN2 spin tests, and 3 servicing passive system tests. It is concluded that the TVC subsystem operated nominally in response to the given commands and test conditions. Test objectives, detail results, and data are included.

Pagan, B.

1981-01-01

364

Least squares support vector machines for direction of arrival estimation with error control and validation.  

SciTech Connect

The paper presents a multiclass, multilabel implementation of least squares support vector machines (LS-SVM) for direction of arrival (DOA) estimation in a CDMA system. For any estimation or classification system, the algorithm's capabilities and performance must be evaluated. Specifically, for classification algorithms, a high confidence level must exist along with a technique to tag misclassifications automatically. The presented learning algorithm includes error control and validation steps for generating statistics on the multiclass evaluation path and the signal subspace dimension. The error statistics provide a confidence level for the classification accuracy.

Christodoulou, Christos George (University of New Mexico, Albuquerque, NM); Abdallah, Chaouki T. (University of New Mexico, Albuquerque, NM); Rohwer, Judd Andrew

2003-02-01

365

Retaking sleeping sickness control in Angola.  

PubMed

Africa is severely affected by a resurgence of human African trypanosomiasis (HAT) at epidemic proportions. We report the results of the first 5 years of a HAT control programme in northern Angola run by the non-governmental organization (NGO) ANGOTRIP. In the period between 1996 and 2001, 13 426 patients were screened for HAT. The mortality rate of patients in stage II who were treated with melarsoprol fell from 7.5% to 2.9%, possibly as a result of training and the standardization of treatment protocols. A total of 191,578 people in three provinces of Angola were screened for HAT. Vector control activities were initiated using Lancien traps. Our experiences reflect the connection between war and the increasing incidence of disease, but also demonstrate that HAT control is possible by dedicated NGOs in close cooperation with national institutions even under extremely difficult circumstances. PMID:14728618

Abel, Paulo M; Kiala, Godi; Lôa, Vanda; Behrend, Markus; Musolf, Jens; Fleischmann, Hanne; Théophile, Josénando; Krishna, Sanjeev; Stich, August

2004-01-01

366

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

PubMed Central

Background Intensive anti-malaria campaigns targeting the Anopheles population have demonstrated substantial reductions in adult mosquito density. Understanding the population dynamics of Anopheles mosquitoes throughout their whole lifecycle is important to assess the likely impact of vector control interventions alone and in combination as well as to aid the design of novel interventions. Methods An ecological model of Anopheles gambiae sensu lato populations incorporating a rainfall-dependent carrying capacity and density-dependent regulation of mosquito larvae in breeding sites is developed. The model is fitted to adult mosquito catch and rainfall data from 8 villages in the Garki District of Nigeria (the 'Garki Project') using Bayesian Markov Chain Monte Carlo methods and prior estimates of parameters derived from the literature. The model is used to compare the impact of vector control interventions directed against adult mosquito stages - long-lasting insecticide treated nets (LLIN), indoor residual spraying (IRS) - and directed against aquatic mosquito stages, alone and in combination on adult mosquito density. Results A model in which density-dependent regulation occurs in the larval stages via a linear association between larval density and larval death rates provided a good fit to seasonal adult mosquito catches. The effective mosquito reproduction number in the presence of density-dependent regulation is dependent on seasonal rainfall patterns and peaks at the start of the rainy season. In addition to killing adult mosquitoes during the extrinsic incubation period, LLINs and IRS also result in less eggs being oviposited in breeding sites leading to further reductions in adult mosquito density. Combining interventions such as the application of larvicidal or pupacidal agents that target the aquatic stages of the mosquito lifecycle with LLINs or IRS can lead to substantial reductions in adult mosquito density. Conclusions Density-dependent regulation of anopheline larvae in breeding sites ensures robust, stable mosquito populations that can persist in the face of intensive vector control interventions. Selecting combinations of interventions that target different stages in the vector's lifecycle will result in maximum reductions in mosquito density. PMID:21798055

2011-01-01

367

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

PubMed Central

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

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

2015-01-01

368

Trial of a minimal-risk botanical compound to control the vector tick of Lyme disease.  

PubMed

We compared the application of IC2, a minimal-risk (25B) botanical compound containing 10% rosemary oil, with bifenthrin, a commonly used synthetic compound, and with water for the control of Ixodes scapularis Say (= Ixodes dammini Spielman, Clifford, Piesman & Corwin), on tick-infested grids in Maine, in an area where Lyme disease is established and other tick-borne diseases are emerging. High-pressure sprays of IC2, bifenthrin, and water were applied during the peak nymphal (July) and adult (October) seasons of the vector tick. No ticks could be dragged on the IC2 grids within 2 wk of the July spray, and few adult ticks were found in October or the following April. Similarly, no adult ticks could be dragged 1.5 wk after the October IC2 spray, and few the following April. No ticks were found on the bifenthrin grids after either spray through the following April, whereas substantial numbers of ticks remained throughout on the grids sprayed with water. Thus, IC2 appears to be an effective, minimum-risk acaricide to control the vector tick of Lyme disease. PMID:20695287

Rand, Peter W; Lacombe, Eleanor H; Elias, Susan P; Lubelczyk, Charles B; St Amand, Theodore; Smith, Robert P

2010-07-01

369

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

PubMed Central

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

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

1999-01-01

370

Is participation contagious? Evidence from a household vector control campaign in urban Peru  

PubMed Central

Objectives High rates of household participation are critical to the success of door-to-door vector control campaigns. We used the Health Belief Model to assess determinants of participation, including neighbor participation as a cue to action, in a Chagas disease vector control campaign in Peru. Methods We evaluated clustering of participation among neighbors; estimated participation as a function of household infestation status, neighborhood type, and number of participating neighbors; and described reported reasons for refusal to participate in a district of 2911 households. Results We observed significant clustering of participation along city blocks (p< .0001). Participation was significantly higher for households in new vs. established neighborhoods, for infested households, and for households with more participating neighbors. The effect of neighbor participation was greater in new neighborhoods. Conclusions Results support a “contagion” model of participation, highlighting the possibility that one or two participating households can tip a block towards full participation. Future campaigns can leverage these findings by making participation more visible, by addressing stigma associated with spraying, and by employing group incentives to spray. PMID:24062411

Buttenheim, Alison M.; Paz-Soldan, Valerie; Barbu, Corentin; Skovira, Christine; Calderón, Javier Quintanilla; Riveros, Lina Margot Mollesaca; Cornejo, Juan Oswaldo; Small, Dylan S.; Bicchieri, Christina; Naquira, Cesar; Levy, Michael Z.

2013-01-01

371

Age-related changes in the control of finger force vectors.  

PubMed

We explored changes in finger interaction in the process of healthy aging as a window into neural control strategies of natural movements. In particular, we quantified the amount of force produced by noninstructed fingers in different directions, the amount of force produced by the instructed finger orthogonally to the task direction, and the strength of multifinger synergies stabilizing the total force magnitude and direction during accurate force production. Healthy elderly participants performed accurate isometric force production tasks in five directions by individual fingers and by all four fingers acting together. Their data were compared with a dataset obtained in a similar earlier study of young subjects. Finger force vectors were measured using six-component force/torque sensors. Multifinger synergies were quantified using the framework of the uncontrolled manifold hypothesis. The elderly participants produced lower force magnitudes by noninstructed fingers and higher force magnitudes by instructed fingers in nontask directions. They showed strong synergies stabilizing the magnitude and direction of the total force vector. However, the synergy indexes were significantly lower than those observed in the earlier study of young subjects. The results are consistent with an earlier hypothesis of preferential weakening of intrinsic hand muscles with age. We interpret the findings as a shift in motor control from synergic to element-based, which may be causally linked to the documented progressive neuronal death at different levels of the neural axis. PMID:20829494

Kapur, Shweta; Zatsiorsky, Vladimir M; Latash, Mark L

2010-12-01

372

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

NASA Astrophysics Data System (ADS)

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 as well as to potentially isolate dynamic responses from the satellite structure bus. Since the disturbance due to the satellite thruster firing can be estimated, a combined strategy of an adaptive disturbance observer (DOB) and feed-forward control is proposed for vibration suppression of the ACCP with multi-sensors and multi-actuators. Meanwhile, the effects of the DOB cut-off frequency and the relative degree of the low-pass filter on the DOB performance are investigated. Simulations and experimental results show that higher relative degree of the low-pass filter with the required cut-off frequency will enhance the DOB performance for a high-order system control. Further, although the increase of the filter cut-off frequency can guarantee a sufficient stability margin, it may cause an undesirable increase of the control bandwidth. The effectiveness of the proposed adaptive DOB with feed-forward control strategy is verified through simulations and experiments using the ACCP system.

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

2008-03-01

373

SCYX-7158, an Orally-Active Benzoxaborole for the Treatment of Stage 2 Human African Trypanosomiasis  

Microsoft Academic Search

BackgroundHuman African trypanosomiasis (HAT) is an important public health problem in sub-Saharan Africa, affecting hundreds of thousands of individuals. An urgent need exists for the discovery and development of new, safe, and effective drugs to treat HAT, as existing therapies suffer from poor safety profiles, difficult treatment regimens, limited effectiveness, and a high cost of goods. We have discovered and

Robert T. Jacobs; Bakela Nare; Stephen A. Wring; Matthew D. Orr; Daitao Chen; Jessica M. Sligar; Matthew X. Jenks; Robert A. Noe; Tana S. Bowling; Luke T. Mercer; Cindy Rewerts; Eric Gaukel; Jennifer Owens; Robin Parham; Ryan Randolph; Beth Beaudet; Cyrus J. Bacchi; Nigel Yarlett; Jacob J. Plattner; Yvonne Freund; Charles Ding; Tsutomu Akama; Y.-K. Zhang; Reto Brun; Marcel Kaiser; Ivan Scandale; Robert Don

2011-01-01

374

The Genome Sequence of Trypanosoma brucei gambiense, Causative Agent of Chronic Human African Trypanosomiasis  

Microsoft Academic Search

BackgroundTrypanosoma brucei gambiense is the causative agent of chronic Human African Trypanosomiasis or sleeping sickness, a disease endemic across often poor and rural areas of Western and Central Africa. We have previously published the genome sequence of a T. b. brucei isolate, and have now employed a comparative genomics approach to understand the scale of genomic variation between T. b.

Andrew P. Jackson; Mandy Sanders; Andrew Berry; Jacqueline McQuillan; Martin A. Aslett; Michael A. Quail; Bridget Chukualim; Paul Capewell; Annette MacLeod; Sara E. Melville; Wendy Gibson; J. David Barry; Matthew Berriman; Christiane Hertz-Fowler

2010-01-01

375

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

PubMed Central

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

Barbu, Corentin; Dumonteil, Eric; Gourbière, Sébastien

2009-01-01

376

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

PubMed Central

Background Malaria is endemic with year-round transmission on Bioko Island. The Bioko Island Malaria Control Project (BIMCP) started in 2004 with the aim to reduce malaria transmission and to ultimately eliminate malaria. While the project has been successful in reducing overall malaria morbidity and mortality, foci of high malaria transmission still persist on the island. Results from the 2009 entomological collections are reported here. Methods Human landing collections (HLC) and light trap collections (LTC) were carried out on Bioko Island, Equatorial Guinea in 2009. The HLCs were performed in three locations every second month and LTCs were carried out in 10 locations every second week. Molecular analyses were performed to identify species, detect sporozoites, and identify potential insecticide resistance alleles. Results The entomological inoculation rates (EIR) on Bioko Island ranged from 163 to 840, with the outdoor EIRs reaching > 900 infective mosquito bites per year. All three human landing collection sites on Bioko Island had an annual EIR exceeding the calculated African average of 121 infective bites per year. The highest recorded EIRs were in Punta Europa in northwestern Bioko Island with human biting rates of 92 and 66 mosquito landings per person per night, outdoors and indoors, respectively. Overall, the propensity for mosquito biting on the island was significantly higher outdoors than indoors (p < 0.001). Both Anopheles gambiae s.s. and An. melas were responsible for malaria transmission on the island, but with different geographical distribution patterns. Sporozoite rates were the highest in An. gambiae s.s. populations ranging from 3.1% in Punta Europa and 5.7% in Riaba in the southeast. Only the L1014F (kdr-west) insecticide resistance mutation was detected on the island with frequencies ranging from 22-88% in An. gambiae s.s. No insecticide resistance alleles were detected in the An. melas populations. Conclusions In spite of five years of extensive malaria control and a generalized reduction in the force of transmission, parasite prevalence and child mortality, foci of very high transmission persist on Bioko Island, particularly in the northwestern Punta Europa area. This area is favorable for anopheline mosquito breeding; human biting rates are high, and the EIRs are among the highest ever recorded. Both vector species collected in the study have a propensity to bite outdoors more frequently than indoors. Despite current vector control efforts mosquito densities remain high in such foci of high malaria transmission. To further reduce transmission, indoor residual spraying (IRS) needs to be supplemented with additional vector control interventions. PMID:23146423

2012-01-01

377

Thrust-vector control of a three-axis stabilized upper-stage rocket with fuel slosh dynamics  

NASA Astrophysics Data System (ADS)

This paper studies the thrust vector control problem for an upper-stage rocket with fuel slosh dynamics. The dynamics of a three-axis stabilized spacecraft with a single partially-filled fuel tank are formulated and the sloshing propellant is modeled as a multi-mass-spring system, where the oscillation frequencies of the mass-spring elements represent the prominent sloshing modes. The equations of motion are expressed in terms of the three-dimensional spacecraft translational velocity vector, the attitude, the angular velocity, and the internal coordinates representing the slosh modes. A Lyapunov-based nonlinear feedback control law is proposed to control the translational velocity vector and the attitude of the spacecraft, while attenuating the sloshing modes characterizing the internal dynamics. A simulation example is included to illustrate the effectiveness of the control law.

Rubio Hervas, Jaime; Reyhanoglu, Mahmut

2014-05-01

378

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

PubMed

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

Gürtler, Ricardo E; Yadon, Zaida E

2015-02-01

379

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

PubMed Central

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

Gürtler, Ricardo E.; Yadon, Zaida E.

2015-01-01

380

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

PubMed

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

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

2013-09-01

381

Control of Insect Vectors in the Japanese Empire: Transformation of the Colonial\\/Metropolitan Environment, 1920–1945  

Microsoft Academic Search

This paper discusses the establishment of insect pest control in Japan for preventing disease transmission. In the late nineteenth century, after the establishment of tropical medicine in Great Britain, many insects were recognized as vectors. However, it was only after the 1920s that the control of insects became a social agenda in Japan. In colonial Taiwan, the transformation of the

Akihisa Setoguchi

2007-01-01

382

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

PubMed Central

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

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

383

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

PubMed Central

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

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

2011-01-01

384

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

PubMed

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

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

385

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

PubMed Central

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

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

386

Major QTLs control resistance to rice hoja blanca virus and its vector Tagosodes orizicolus.  

PubMed

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

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

2014-01-01

387

Implementation of the Orbital Maneuvering Systems Engine and Thrust Vector Control for the European Service Module  

NASA Technical Reports Server (NTRS)

The European Space Agency (ESA) has entered into a partnership with the National Aeronautics and Space Administration (NASA) to develop and provide the Service Module (SM) for the Orion Multipurpose Crew Vehicle (MPCV) Program. The European Service Module (ESM) will provide main engine thrust by utilizing the Space Shuttle Program Orbital Maneuvering System Engine (OMS-E). Thrust Vector Control (TVC) of the OMS-E will be provided by the Orbital Maneuvering System (OMS) TVC, also used during the Space Shuttle Program. NASA will be providing the OMS-E and OMS TVC to ESA as Government Furnished Equipment (GFE) to integrate into the ESM. This presentation will describe the OMS-E and OMS TVC and discuss the implementation of the hardware for the ESM.

Millard, Jon

2014-01-01

388

PAB3D Simulations of a Nozzle with Fluidic Injection for Yaw Thrust-Vector Control  

NASA Technical Reports Server (NTRS)

An experimental and computational study was conducted on an exhaust nozzle with fluidic injection for yaw thrust-vector control. The nozzle concept was tested experimentally in the NASA Langley Jet Exit Test Facility (JETF) at nozzle pressure ratios up to 4 and secondary fluidic injection flow rates up to 15 percent of the primary flow rate. Although many injection-port geometries and two nozzle planforms (symmetric and asymmetric) were tested experimentally, this paper focuses on the computational results of the more successful asymmetric planform with a slot injection port. This nozzle concept was simulated with the Navier-Stokes flow solver, PAB3D, invoking the Shih, Zhu, and Lumley algebraic Reynolds stress turbulence model (ASM) at nozzle pressure ratios (NPRs) of 2,3, and 4 with secondary to primary injection flow rates (w(sub s)/w(sub p)) of 0, 2, 7 and 10 percent.

Deere, Karen A.

1998-01-01

389

Tsetse Fly Control in Kenya's Spatially and Temporally Dynamic Control Reservoirs: A Cost Analysis  

PubMed Central

Human African trypanosomiasis (HAT) and animal African trypanosomiasis (AAT) are significant health concerns throughout much of sub-Saharan Africa. Funding for tsetse fly control operations has decreased since the 1970s, which has in turn limited the success of campaigns to control the disease vector. To maximize the effectiveness of the limited financial resources available for tsetse control, this study develops and analyzes spatially and temporally dynamic tsetse distribution maps of Glossina subgenus Morsitans populations in Kenya from January 2002 to December 2010, produced using the Tsetse Ecological Distribution Model. These species distribution maps reveal seasonal variations in fly distributions. Such variations allow for the identification of “control reservoirs” where fly distributions are spatially constrained by fluctuations in suitable habitat and tsetse population characteristics. Following identification of the control reservoirs, a tsetse management operation is simulated in the control reservoirs using capital and labor control inputs from previous studies. Finally, a cost analysis, following specific economic guidelines from existing tsetse control analyses, is conducted to calculate the total cost of a nationwide control campaign of the reservoirs compared to the cost of a nationwide campaign conducted at the maximum spatial extent of the fly distributions from January 2002 to December 2010. The total cost of tsetse management within the reservoirs sums to $14,212,647, while the nationwide campaign at the maximum spatial extent amounts to $33,721,516. This savings of $19,508,869 represents the importance of identifying seasonally dynamic control reservoirs when conducting a tsetse management campaign, and, in the process, offers an economical means of fly control and disease management for future program planning. PMID:22581989

McCord, Paul F.; Messina, Joseph P.; Campbell, David J.; Grady, Sue C.

2011-01-01

390

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

PubMed Central

Background Research has shown that the classical Stegomyia indices (or “larval indices”) of the dengue vector Aedes aegypti reflect the absence or presence of the vector but do not provide accurate measures of adult mosquito density. In contrast, pupal indices as collected in pupal productivity surveys are a much better proxy indicator for adult vector abundance. However, it is unknown when it is most optimal to conduct pupal productivity surveys, in the wet or in the dry season or in both, to inform control services about the most productive water container types and if this pattern varies among different ecological settings. Methods A multi-country study in randomly selected twelve to twenty urban and peri-urban neighborhoods (“clusters”) of six Asian countries, in which all water holding containers were examined for larvae and pupae of Aedes aegypti during the dry season and the wet season and their productivity was characterized by water container types. In addition, meteorological data and information on reported dengue cases were collected. Findings The study reconfirmed the association between rainfall and dengue cases (“dengue season”) and underlined the importance of determining through pupal productivity surveys the “most productive containers types”, responsible for the majority (>70%) of adult dengue vectors. The variety of productive container types was greater during the wet than during the dry season, but included practically all container types productive in the dry season. Container types producing pupae were usually different from those infested by larvae indicating that containers with larval infestations do not necessarily foster pupal development and thus the production of adult Aedes mosquitoes. Conclusion Pupal productivity surveys conducted during the wet season will identify almost all of the most productive container types for both the dry and wet seasons and will therefore facilitate cost-effective targeted interventions. PMID:23318235

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

2012-01-01

391

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

PubMed

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

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

392

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

PubMed Central

Background Formerly a high malaria transmission area, Zanzibar is now targeting malaria elimination. A major challenge is to avoid resurgence of malaria, the success of which includes maintaining high effective coverage of vector control interventions such as bed nets and indoor residual spraying (IRS). In this study, caretakers' continued use of preventive measures for their children is evaluated, following a sharp reduction in malaria transmission. Methods A cross-sectional community-based survey was conducted in June 2009 in North A and Micheweni districts in Zanzibar. Households were randomly selected using two-stage cluster sampling. Interviews were conducted with 560 caretakers of under-five-year old children, who were asked about perceptions on the malaria situation, vector control, household assets, and intention for continued use of vector control as malaria burden further decreases. Results Effective coverage of vector control interventions for under-five children remains high, although most caretakers (65%; 363/560) did not perceive malaria as presently being a major health issue. Seventy percent (447/643) of the under-five children slept under a long-lasting insecticidal net (LLIN) and 94% (607/643) were living in houses targeted with IRS. In total, 98% (628/643) of the children were covered by at least one of the vector control interventions. Seasonal bed-net use for children was reported by 25% (125/508) of caretakers of children who used bed nets. A high proportion of caretakers (95%; 500/524) stated that they intended to continue using preventive measures for their under-five children as malaria burden further reduces. Malaria risk perceptions and different perceptions of vector control were not found to be significantly associated with LLIN effective coverage. Conclusions While the majority of caretakers felt that malaria had been reduced in Zanzibar, effective coverage of vector control interventions remained high. Caretakers appreciated the interventions and recognized the value of sustaining their use. Thus, sustaining high effective coverage of vector control interventions, which is crucial for reaching malaria elimination in Zanzibar, can be achieved by maintaining effective delivery of these interventions. PMID:23360479

2013-01-01

393

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

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

394

Results of solar electric thrust vector control system design, development and tests  

NASA Technical Reports Server (NTRS)

Efforts to develop and test a thrust vector control system TVCS for a solar-energy-powered ion engine array are described. The results of solar electric propulsion system technology (SEPST) III real-time tests of present versions of TVCS hardware in combination with computer-simulated attitude dynamics of a solar electric multi-mission spacecraft (SEMMS) Phase A-type spacecraft configuration are summarized. Work on an improved solar electric TVCS, based on the use of a state estimator, is described. SEPST III tests of TVCS hardware have generally proved successful and dynamic response of the system is close to predictions. It appears that, if TVCS electronic hardware can be effectively replaced by control computer software, a significant advantage in control capability and flexibility can be gained in future developmental testing, with practical implications for flight systems as well. Finally, it is concluded from computer simulations that TVCS stabilization using rate estimation promises a substantial performance improvement over the present design.

Fleischer, G. E.

1973-01-01

395

Fuzzy-tuning current-vector control of a three-phase PWM inverter for high-performance AC drives  

Microsoft Academic Search

This paper proposes a new discrete fuzzy-tuning current-vector control (FTC) scheme for three-phase pulsewidth modulation (PWM) inverters. The proposed current control scheme can achieve fast transient responses and, at the same time, have very low total harmonic distortion in output current during steady-state operation. The proposed FTC scheme generates quasi-optimum PWM patterns by using a closed-loop control technique with instantaneous

Ying-Yu Tzou; Shiu-Yung Lin

1998-01-01

396

Proposed use of spatial mortality assessments as part of the pesticide evaluation scheme for vector control  

PubMed Central

Background The WHO Pesticide Evaluation Scheme to evaluate the efficacy of insecticides does not include the testing of a lethal effect at a distance. A tool was developed to evaluate the spatial mortality of an insecticide product against adult mosquitoes at a distance under laboratory and field conditions. Operational implications are discussed. Methods Insecticide paint, Inesfly 5A IGR™, containing two organophosphates (OPs): chlorpyrifos and diazinon, and one insect growth regulator (IGR): pyriproxyfen, was the product tested. Laboratory tests were performed using “distance boxes” with surfaces treated with one layer of control or insecticide paint at a dose of 1 kg/6 sq m. Field tests were conducted up to 12 months in six experimental huts randomly allocated to control or one or two layers of insecticide paint at 1 kg/6 sq m. All distance tests were performed using reference-susceptible strains of Anopheles gambiae and Culex quinquefasciatus left overnight at a distance of 1 m from control or treated surfaces. Results After an overnight exposition at distances of 1 m, field and laboratory evaluations at 0 months after treatment (T0) yielded 100% mortality rates on surfaces treated with one layer at 1 kg/6 sq m against susceptible strains of An. gambiae and Cx. quinquefasciatus. Testing for long-term efficacy in the field gave mortality rates of 96-100% after an overnight exposition at a distance of 1 m for up to 12 months in huts where a larger volume was treated (walls and ceilings) with one or two layers of insecticide paint. Conclusion A comprehensive evaluation of the full profile of insecticide products, both upon contact and spatially, may help rationalize vector control efforts more efficiently. Treating a large enough volume may extend a product’s mortality efficacy in the long-term, which contact tests would fail to assess. It is hereby proposed to explore the development of cost effective methods to assess spatial mortality and to include them as one additional measurement of insecticide efficacy against mosquitoes and other arthropod vectors in WHOPES Phase I and Phase II studies. PMID:24139513

2013-01-01

397

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

PubMed Central

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

2010-01-01

398

Monitoring the aquatic toxicity of mosquito vector control spray pesticides to freshwater receiving waters.  

PubMed

Pesticides are applied to state and local waterways in California to control insects such as mosquitoes, which are known to serve as a vector for West Nile Virus infection of humans. The California State Water Resources Control Board adopted a National Pollutant Discharge Elimination System General Permit to address the discharge to waters of the United States of pesticides resulting from adult and larval mosquito control. Because pesticides used in spray activities have the potential to cause toxicity to nontarget organisms in receiving waters, the current study was designed to determine whether toxicity testing provides additional, useful environmental risk information beyond chemical analysis in monitoring spray pesticide applications. Monitoring included a combination of aquatic toxicity tests and chemical analyses of receiving waters from agricultural, urban, and wetland habitats. The active ingredients monitored included the organophosphate pesticides malathion and naled, the pyrethroid pesticides etofenprox, permethrin, and sumithrin, pyrethrins, and piperonyl butoxide (PBO). Approximately 15% of the postapplication water samples were significantly toxic. Toxicity of half of these samples was attributed to the naled breakdown product dichlorvos. Toxicity of 2 other water samples likely occurred when PBO synergized the effects of pyrethroid pesticides that were likely present in the receiving system. Four of 43 postapplication sediment samples were significantly more toxic than their corresponding pre-application samples, but none of the observed toxicity was attributed to the application events. These results indicate that many of the spray pesticides used for adult mosquito control do not pose significant acute toxicity risk to invertebrates in receiving systems. In the case of naled in water, analysis of only the active ingredient underestimated potential impacts to the receiving system, because toxicity was attributed to the breakdown product, dichlorvos. Toxicity testing can provide useful risk information about unidentified, unmeasured toxicants or mixtures of toxicants. In this case, toxicity testing provided information that could lead to the inclusion of dichlorvos monitoring as a permit requirement. PMID:24659580

Phillips, Bryn M; Anderson, Brian S; Voorhees, Jennifer P; Siegler, Katie; Denton, Debra; TenBrook, Patti; Larsen, Karen; Isorena, Philip; Tjeerdema, Ron S

2014-07-01

399

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

PubMed

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

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

2009-09-01

400

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

PubMed

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

Singla, Rajesh; Khosla, Arun; Jha, Rameshwar

2014-04-01

401

Benzoxaboroles: a new class of potential drugs for human African trypanosomiasis.  

PubMed

Human African trypanosomiasis, caused by the kinetoplastid parasite Trypanosoma brucei, affects thousands of people across sub-Saharan Africa, and is fatal if left untreated. Treatment options for this disease, particularly stage 2 disease, which occurs after parasites have infected brain tissue, are limited due to inadequate efficacy, toxicity and the complexity of treatment regimens. We have discovered and optimized a series of benzoxaborole-6-carboxamides to provide trypanocidal compounds that are orally active in murine models of human African trypanosomiasis. A key feature of this series is the presence of a boron atom in the heterocyclic core structure, which is essential to the observed trypanocidal activity. We also report the in vivo pharmacokinetic properties of lead compounds from the series and selection of SCYX-7158 as a preclinical candidate. PMID:21859301

Jacobs, Robert T; Plattner, Jacob J; Nare, Bakela; Wring, Stephen A; Chen, Daitao; Freund, Yvonne; Gaukel, Eric G; Orr, Matthew D; Perales, Joe B; Jenks, Matthew; Noe, Robert A; Sligar, Jessica M; Zhang, Yong-Kang; Bacchi, Cyrus J; Yarlett, Nigel; Don, Robert

2011-08-01

402

Substituted 2-Phenyl-Imidazopyridines: A New Class of Drug Leads for Human African Trypanosomiasis  

PubMed Central

A phenotypic screen of a compound library for antiparasitic activity on Trypanosoma brucei, the causative agent of human African trypanosomiasis, led to the identification of substituted 2-(3-aminophenyl) oxazolopyridines as a starting point for hit-to-lead medicinal chemistry. A total of 110 analogues were prepared, which led to the identification of 64, a substituted 2-(3-aminophenyl) imidazopyridine. This compound showed antiparasitic activity in vitro with an EC50 of 2 nM and displayed reasonable drug-like properties when tested in a number of in vitro assays. The compound was orally bioavailable and displayed good plasma and brain exposure in mice. Compound 64 cured mice infected with Trypanosoma brucei when dosed orally down to 2.5 mg/kg. Given its potent anti-parasitic properties and its ease of synthesis, compound 64 represents a new lead for the development of drugs to treat human African trypanosomiasis. PMID:24354316

Tatipaka, Hari Babu; Gillespie, J. Robert; Chatterjee, Arnab K.; Norcross, Neil R.; Hulverson, Matthew A.; Ranade, Ranae M.; Nagendar, Pendem; Creason, Sharon A.; McQueen, Joshua; Duster, Nicole A.; Nagle, Advait; Supek, Frantisek; Molteni, Valentina; Wenzler, Tanja; Brun, Reto; Glynne, Richard; Buckner, Frederick S.; Gelb, Michael H.

2014-01-01

403

Vector-Borne Diseases  

NSDL National Science Digital Library

This online encyclopedia article discusses vector-borne diseases. It defines vectors as the transmitters of disease-causing organisms that carry the pathogens from one host to another. The article reviews the biological range of vectors, the transmission and types of vector-borne diseases, patterns of occurrence and existing control measures.

Harvey Artsob

404

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

Microsoft Academic Search

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

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

2004-01-01

405

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

Microsoft Academic Search

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

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

406

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...

407

Wide-Speed-Range Sensorless Vector Control of Synchronous Reluctance Motors Based on Extended Programmable Cascaded Low-Pass Filters  

Microsoft Academic Search

This paper proposes a new sensorless vector control of a synchronous reluctance motor for a wide range of speeds. The estimation of speed and rotor angle is based on extended programmable cascaded low-pass filters (LPFs), which effectively reduce the effects of direct-current (dc) offsets at low speeds. The effect of the number of LPF stages on output dc offset, estimation

Ahmad Ghaderi; Tsuyoshi Hanamoto

2011-01-01

408

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

Microsoft Academic Search

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

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

2009-01-01

409

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

Microsoft Academic Search

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

Joachim Holtz; Juntao Quan

2002-01-01

410

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

NASA Technical Reports Server (NTRS)

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.

Lominick, J. M.

1980-01-01

411

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

Microsoft Academic Search

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

Joachim Holtz; Juntao Quan

2001-01-01

412

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

Microsoft Academic Search

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

Mehrdad Kazerani; Boon-Teck Ooi

1995-01-01

413

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

Microsoft Academic Search

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

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

2006-01-01

414

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

Microsoft Academic Search

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

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

2010-01-01

415

Development and control of a vectored water-jet-based spherical underwater vehicle  

Microsoft Academic Search

This paper presents a spherical underwater vehicle which uses three vectored water-jet propulsion systems. In this paper, firstly, we proposed the concept of a vectored water-jet based spherical underwater vehicle. Then we give the basic design of this underwater vehicle. The working principles of the vectored water-jet propellers is illustrated including the transformation of reference frames, the distribution of propellers

Shuxiang Guo; Xichuan Lin; Koujirou Tanaka; Seji Hata

2010-01-01

416

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

NASA Technical Reports Server (NTRS)

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.

1974-01-01

417

A current analysis of chemotherapy strategies for the treatment of human African trypanosomiasis  

PubMed Central

Despite the recent advances in drug research, finding a safe, effective, and easy to use chemotherapy for human African trypanosomiasis (HAT) remains a challenging task. The four current anti-trypanosomiasis drugs have major disadvantages that limit more widespread use of these drugs in the endemic regions of sub-Saharan Africa. Pentamidine and suramin are limited by their effectiveness against the only first stage of Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense, respectively. In addition, melarsoprol and eflornithine (two second stage drugs) each have disadvantages of their own. The former is toxic and has increasing treatment failures while the latter is expensive, laborious to administer, and lacks efficacy against T. b. rhodesiense. Furthermore, melarsoprol’s toxicity and decreasing efficacy are glaring problems and phasing out the drug as a frontline treatment against T. b. gambiense is now possible with the emergence of competent, safe combination chemotherapies such as nifurtimox–eflornithine combination treatment (NECT). The future of eflornithine, on the other hand, is more promising. The drug is useful in the context of combination chemotherapy and potential orally administered analogues. Due to the limits of monotherapies, greater emphasis should be placed on the research and development of combination chemotherapies, based on the successful clinical tests with NECT and its current use as a frontline anti-trypanosomiasis treatment. This review discussed the current and future chemotherapy strategies for the treatment of HAT. PMID:23916333

Babokhov, Peter; Sanyaolu, Adekunle O; Oyibo, Wellington A; Fagbenro-Beyioku, Adetayo F; Iriemenam, Nnaemeka C

2013-01-01

418

Human African trypanosomiasis with 7-year incubation period: clinical, laboratory and neuroimaging findings.  

PubMed

Human African trypanosomiasis (HAT), also referred to as "sleeping sickness", is caused by the parasite Trypanosoma brucei. Diagnosing imported HAT outside endemic areas is difficult and diagnosis is often delayed. We report a case of imported human African trypanosomiasis caused by Trypanosoma brucei gambiense with an unusually long incubation period of at least 7 years. A 33 year old male African patient, a former resident of Cameroon, presented with a 4-month history of progressive personality changes. A few weeks before presentation the patient had first been admitted to a psychiatric ward and received antidepressant treatment, until a lumbar puncture showed pleocytosis and then antibiotic treatment for suspected neuroborreliosis was initiated. The patient continued to deteriorate during antibiotic treatment and became increasingly lethargic. Under antiparasitic and anti-inflammatory treatment, the condition of the patient gradually improved over the following months and he recovered completely after 24 months of follow-up. This well-documented case illustrates typical difficulties in establishing the correct diagnosis outside endemic areas and provides an overview of typical clinical, neuropathological and neuroimaging findings in T. b. gambiense trypanosomiasis, guiding the clinician in establishing the correct diagnosis in this rare disease. PMID:24613272

Wengert, Oliver; Kopp, Marcel; Siebert, Eberhard; Stenzel, Werner; Hegasy, Guido; Suttorp, Norbert; Stich, August; Zoller, Thomas

2014-06-01

419

The efficacy of pentamidine in the treatment of early-late stage Trypanosoma brucei gambiense trypanosomiasis.  

PubMed

Fifty-eight patients in the early-late stage (early central nervous system involvement) of Trypanosoma brucei gambiense trypanosomiasis were treated with pentamidine and divided into four groups (G1, G2, G3, and G4) according to cerebrospinal fluid (CSF) indicators: white blood cell (WBC) count, protein level (CSF protein), and the presence or absence of trypanosomes. Group G1 consisted of eight patients with normal CSF WBC counts and CSF protein levels and trypanosomes in the CSF. Group G2 consisted of nine patients with elevated CSF WBC counts, normal level of CSF protein, and trypanosomes in the CSF. Group G3 consisted of 31 patients with high CSF WBC counts, normal CSF protein levels, but no trypanosomes in the CSF. Group G4 consisted of 10 patients with normal CSF WBC counts and CSF protein levels and trypanosomes demonstrated by CSF culture. Post-treatment follow-up of all patients for at least one year revealed three relapses. There were two deaths from diseases unrelated to trypanosomiasis or to the treatment protocol. Of these patients, 52 were followed for more than two years, the time necessary to confirm a complete cure, indicating a cure rate of 94%. Pentamidine is therefore effective in treating the early-late stage of T. b. gambiense trypanosomiasis, and is comparable with melarsoprol or eflornithine in terms of its tolerance and availability. PMID:9025682

Doua, F; Miezan, T W; Sanon Singaro, J R; Boa Yapo, F; Baltz, T

1996-12-01

420

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

PubMed Central

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

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

2012-01-01

421

A sensorless vector control system for induction motors using q-axis flux with stator resistance identification  

Microsoft Academic Search

This paper presents a sensorless vector control system for general-purpose induction motors, which is based on the observer theory and the adaptive control theories. The proposed system includes a rotor speed estimator using a q-axis flux and stator resistance identifier using the d-axis flux. The advantages of the proposed system are simplicity and avoidance of problems caused by using only

Mineo Tsuji; Shuo Chen; Katsuhiro Izumi; Eiji Yamada

2001-01-01

422

Simple direct power control of three-phase PWM rectifier using space-vector modulation (DPC-SVM)  

Microsoft Academic Search

This paper proposes a novel and simple direct power control of three-phase pulsewidth-modulated (PWM) rectifiers with constant switching frequency using space-vector modulation (DPC-SVM). The active and reactive powers are used as the pulse width modulated (PWM) control variables instead of the three-phase line currents being used. Moreover, line voltage sensors are replaced by a virtual flux estimator. The theoretical principle

Mariusz Malinowski; M. Jasinski; M. P. Kazmierkowski

2004-01-01

423

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

Microsoft Academic Search

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

Roberto Cárdenas; Rubén Peña; Greg Asher; Jon Clare

2001-01-01

424

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

PubMed

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

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

2013-01-01

425

Inductance and Active Phase Vector Based Torque Control for Switched Reluctance Motor Drives.  

NASA Astrophysics Data System (ADS)

The Switched Reluctance Motor (SRM) drive technology has developed significantly over the last few years. The simplicity in both motor design and power converter requirement along with the availability of high frequency, high power semiconductor switches have made SRMs compete with conventional adjustable speed drive technologies. The subject of winding current control in switched reluctance machines has always been associated with the shaft position information. The use of inductance for direct commutation control is the central subject of this dissertation. In contrast to the conventional methods based on position commutation, new methods of control based on inductance commutation are presented. The object of a commutation algorithm is to switch the currents in the phase coils, in order to provide continuous energy conversion with maximum torque output for a given unit of input current. Since torque production in a SRM is based on the concept of variable reluctance, it makes more sense to observe the instantaneous phase inductance or reluctance instead of estimating the rotor position. The inductance sensors observe the machine parameters and provide sufficient information on the electrical characteristics of the coils. This control strategy avoids the inductance to position transformation blocks conventionally used in SRM control systems. In a typical SRM, the phase coils have a nonlinear behavior of inductance due to effects of current saturation. Also the parameters of one phase coil differ from those of the other due to manufacturing tolerances or due to bearing wear. In such cases, the algorithms written during the stage of manufacturing may not be valid after parameter changes. Optimizing torque production in the event of phase asymmetry and saturation is developed in this research. Indirect sensors connected to the active phase coil of the SRM are based on sensing the flux level in the active coil. New commutation algorithms based on flux sensing concepts are derived and commutation based on observable phase coil parameters are developed. The commutation methods are based on a composite vector of the observable parameters of the active phase coil. These methods work on a tabular approach which is ideal for implementation using digital computers.

Kalpathi, Ramani Raman

426

Control of Tripod-Scheme Cold-Atom Wavepackets by Manipulating a non-Abelian Vector Potential  

E-print Network

Tripod-scheme cold atoms interacting with laser beams have attracted considerable interest for their role in synthesizing effective non-Abelian vector potentials. Such effective vector potentials can be exploited to realize an all-optical imprinting of geometric phases onto matter waves. By working on carefully designed extensions of our previous work, we show that coherent lattice structure of cold-atom sub-wavepackets can be formed and that the non-Abelian Aharonov-Bohm effect can be easily manifested via the translational motion of cold atoms. We also show that by changing the frame of reference, effects due to a non-Abelian vector potential may be connected with a simple dynamical phase effect, and that under certain conditions it can be understood as an Abelian geometric phase in a different frame of reference. Results should help design better schemes for the control of cold-atom matter waves.

Qi Zhang; Jiangbin Gong; C. H. Oh

2010-04-16

427

Control of tripod-scheme cold-atom wavepackets by manipulating a non-Abelian vector potential  

SciTech Connect

Tripod-scheme cold atoms interacting with laser beams have attracted considerable interest for their role in synthesizing effective non-Abelian vector potentials. Such effective vector potentials can be exploited to realize an all-optical imprinting of geometric phases onto matter waves. By working on carefully designed extensions of our previous work, we show that coherent lattice structure of cold-atom sub-wavepackets can be formed and that the non-Abelian Aharonov-Bohm effect can be easily manifested via the translational motion of cold atoms. We also show that by changing the frame of reference, effects due to a non-Abelian vector potential may be connected with a simple dynamical phase effect, and that under certain conditions it can be understood as an Abelian geometric phase in a different frame of reference. Results should help design better schemes for the control of cold-atom matter waves.

Zhang Qi, E-mail: cqtzq@nus.edu.s [Centre of Quantum Technologies and Department of Physics, National University of Singapore, 117543 (Singapore); Gong Jiangbin, E-mail: phygj@nus.edu.s [Department of Physics and Centre for Computational Science and Engineering, National University of Singapore, 117542 (Singapore); NUS Graduate School for Integrative Sciences and Engineering, Singapore 117597 (Singapore); Oh, C.H., E-mail: phyohch@nus.edu.s [Centre of Quantum Technologies and Department of Physics, National University of Singapore, 117543 (Singapore); Institute of Advanced Studies, Nanyang Technological University, Singapore 639798 (Singapore)

2010-06-15

428

Application of Diagnostic Analysis Tools to the Ares I Thrust Vector Control System  

NASA Technical Reports Server (NTRS)

The NASA Ares I Crew Launch Vehicle is being designed to support missions to the International Space Station (ISS), to the Moon, and beyond. The Ares I is undergoing design and development utilizing commercial-off-the-shelf tools and hardware when applicable, along with cutting edge launch technologies and state-of-the-art design and development. In support of the vehicle s design and development, the Ares Functional Fault Analysis group was tasked to develop an Ares Vehicle Diagnostic Model (AVDM) and to demonstrate the capability of that model to support failure-related analyses and design integration. One important component of the AVDM is the Upper Stage (US) Thrust Vector Control (TVC) diagnostic model-a representation of the failure space of the US TVC subsystem. This paper first presents an overview of the AVDM, its development approach, and the software used to implement the model and conduct diagnostic analysis. It then uses the US TVC diagnostic model to illustrate details of the development, implementation, analysis, and verification processes. Finally, the paper describes how the AVDM model can impact both design and ground operations, and how some of these impacts are being realized during discussions of US TVC diagnostic analyses with US TVC designers.

Maul, William A.; Melcher, Kevin J.; Chicatelli, Amy K.; Johnson, Stephen B.

2010-01-01

429

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

PubMed Central

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

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

430

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

PubMed

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

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

2013-03-20

431

Independent Orbiter Assessment (IOA): Assessment of the ascent thrust vector control actuator subsystem FMEA/CIL  

NASA Technical Reports Server (NTRS)

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA effort first completed an analysis of the Ascent Thrust Vector Control Actuator (ATVD) hardware, generating draft failure modes and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The IOA results were then compared to the NASA FMEA/CIL baseline with proposed Post 51-L updates included. A resolution of each discrepancy from the comparison is provided through additional analysis as required. This report documents the results of that comparison for the Orbiter ATVC hardware. The IOA product for the ATVC actuator analysis consisted of 25 failure mode worksheets that resulted in 16 potential critical items being identified. Comparison was made to the NASA baseline which consisted of 21 FMEAs and 13 CIL items. This comparison produced agreement on all CIL items. Based on the Pre 51-L baseline, all non-CIL FMEAs were also in agreement.

Wilson, R. E.

1988-01-01

432

The Changing Epidemiology of Human African Trypanosomiasis among Patients from Nonendemic Countries –1902–2012  

PubMed Central

Background Although human African trypanosomiasis (HAT) is uncommon among patients from non-endemic countries (NEC), there has been an increase in the number of cases reported in recent years. Methods A systematic review of the literature was performed. The number of incoming tourists to HAT endemic countries was obtained from the United Nations World Tourism Organization. All HAT cases diagnosed in patients from NEC were included. Immigrants and refugees were excluded. We compared patients during and after the colonial period, and analyzed the relationship between the number of incoming travellers and the number of HAT cases. Results Between 1902 and 2012, HAT was reported in 244 patients. Most HAT cases were reported before 1920, and after the year 2000. In the colonial era the average age of patients was lower (32.5±7.8 vs. 43.0±16.1 years, P<0.001), the proportion of females was lower (10.0% vs. 23.9%, P<0.01], most cases were diagnosed in expatriates, missionaries and soldiers (74.3%), and Gambian trypanosomiasis accounted for 86/110, (78%) of cases. In the post-colonial era most patients 91/125 (72.8%) were short-term tourists to game parks in Eastern and South-Eastern Africa (mainly in Tanzania); Rhodesian trypanosomiasis accounted for 94/123 (76.4%) of cases. Between 1995 and 2010 there has been a constant linear increase in the number of incoming tourists to Tanzania, and HAT cases occurred in small outbreaks rather than following a similar linear pattern. Conclusions In recent decades HAT patients from NEC are older, and more likely to be tourists who acquired the disease while visiting game-parks in Eastern and South-Eastern Africa. While Rhodesian trypanosomiasis is relatively uncommon among Africans, it now accounts for most cases reported among patients from NEC. Returning febrile travellers without an alternative diagnosis should be evaluated for HAT. Cases among travellers may serve as sentinels for Rhodesian trypanosomiasis “hot spots” in Africa. PMID:24586363

Neuberger, Ami; Meltzer, Eyal; Leshem, Eyal; Dickstein, Yaakov; Stienlauf, Shmuel; Schwartz, Eli

2014-01-01

433

Simulation development and evaluation of an improved longitudinal velocity vector control wheel steering mode and electronic display format  

NASA Technical Reports Server (NTRS)

Using simulation, an improved longitudinal velocity vector control wheel steering mode and an improved electronic display format for an advanced flight system were developed and tested. Guidelines for the development phase were provided by test pilot critique summaries of the previous system. The results include performances from computer generated step column inputs across the full airplane speed and configuration envelope, as well as piloted performance results taken from a reference line tracking task and an approach to landing task conducted under various environmental conditions. The analysis of the results for the reference line tracking and approach to landing tasks indicates clearly detectable improvement in pilot tracking accuracy with a reduction in physical workload. The original objectives of upgrading the longitudinal axis of the velocity vector control wheel steering mode were successfully met when measured against the test pilot critique summaries and the original purpose outlined for this type of augment control mode.

Steinmetz, G. G.

1980-01-01

434

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

PubMed Central

Background Dengue is considered one of the most important vector-borne diseases in Thailand. Its incidence is increasing despite routine implementation of national dengue control programmes. This study, conducted during 2010, aimed to demonstrate an application of integrated, community-based, eco-bio-social strategies in combination with locally-produced eco-friendly vector control tools in the dengue control programme, emphasizing urban and peri-urban settings in eastern Thailand. Methodology Three different community settings were selected and were randomly assigned to intervention and control clusters. Key community leaders and relevant governmental authorities were approached to participate in this intervention programme. Ecohealth volunteers were identified and trained in each study community. They were selected among active community health volunteers and were trained by public health experts to conduct vector control activities in their own communities using environmental management in combination with eco-friendly vector control tools. These trained ecohealth volunteers carried out outreach health education and vector control during household visits. Management of public spaces and public properties, especially solid waste management, was efficiently carried out by local municipalities. Significant reduction in the pupae per person index in the intervention clusters when compared to the control ones was used as a proxy to determine the impact of this programme. Results Our community-based dengue vector control programme demonstrated a significant reduction in the pupae per person index during entomological surveys which were conducted at two-month intervals from May 2010 for the total of six months in the intervention and control clusters. The programme also raised awareness in applying eco-friendly vector control approaches and increased intersectoral and household participation in dengue control activities. Conclusion An eco-friendly dengue vector control programme was successfully implemented in urban and peri-urban settings in Thailand, through intersectoral collaboration and practical action at household level, with a significant reduction in vector densities. PMID:23318236

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

2012-01-01

435

Malaria Vector Species  

NSDL National Science Digital Library

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.

0000-00-00

436

Potential for entomopathogenic fungi to control Triatoma dimidiata (Hemiptera: Reduviidae), a vector of Chagas disease in Mexico.  

PubMed

Introduction The use of entomopathogenic fungi to control disease vectors has become relevant because traditional chemical control methods have caused damage to the environment and led to the development of resistance among vectors. Thus, this study assessed the pathogenicity of entomopathogenic fungi in Triatoma dimidiata. Methods Preparations of 108 conidia/ml of Gliocladium virens, Talaromyces flavus, Beauveria bassiana and Metarhizium anisopliae were applied topically on T. dimidiata nymphs and adults. Controls were treated with the 0.0001% Tween-80 vehicle. Mortality was evaluated and recorded daily for 30 days. The concentration required to kill 50% of T. dimidiata (LC50) was then calculated for the most pathogenic isolate. Results Pathogenicity in adults was similar among B. bassiana, G. virens and T. flavus (p>0.05) and differed from that in triatomine nymphs (p=0.009). The most entomopathogenic strains in adult triatomines were B. bassiana and G. virens, which both caused 100% mortality. In nymphs, the most entomopathogenic strain was B. bassiana, followed by G. virens. The native strain with the highest pathogenicity was G. virens, for which the LC50 for T. dimidiata nymphs was 1.98 x108 conidia/ml at 13 days after inoculation. Conclusions Beauveria bassiana and G. virens showed entomopathogenic potential in T. dimidiata nymphs and adults. However, the native G. virens strain presents a higher probability of success in the field, and G. virens should thus be considered a potential candidate for the biological control of triatomine Chagas disease vectors. PMID:25626650

Vázquez-Martínez, María Guadalupe; Cirerol-Cruz, Blanca Elva; Torres-Estrada, José Luis; López, Mario Henry Rodríguez

2014-12-01

437

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

E-print Network

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 ...

Gianotti, Rebecca Louise

438

Control of arbovirus vector Verrallina funerea (Diptera: Culicidae) in southeast Queensland, Australia.  

PubMed

In Australia, the brackish water mosquito Verrallina funerea (Theobald) (Diptera: Culicidae) is a serious pest and vector of Ross River and Barmah Forest viruses in coastal areas in the northeast of the continent. We report on the first extensive evaluation of the efficacy of various pesticides against this species, including laboratory dose-response assays and small plot field trials. In the laboratory, Ve. funerea was susceptible to temephos (Abate 100E) (lethal concentration, 95% endpoint [LC95] of 1.651 ppb), Bacillus thuringiensis subsp. israelensis de Barjac (Bti) (VectoBac 12AS) (LC95 of 0.033 ppm), s-methoprene (ProLink Liquid Larvicide [PLL]) (emergence inhibition, 95% endpoint [EI95] of 2.647 ppb), and technical grade pyriproxyfen (EI95 of 0.227 ppb). In contrast, Ve.funerea was highly refractory to Bacillus sphaericus Neide (VectoLex WG) (LC95 of >855.3 ppm). The survival of adults exposed as larvae to sublethal doses of s-methoprene was reduced for those doses greater than the EI50, although sex ratios were unaffected. Field trials demonstrated that Ve. funerea was susceptible to Bti (VectoBac G at 7 kg/ha) and s-methoprene (ProLink ProSand at 4 kg/ha), with these products giving >99 and >98% control, respectively. We also observed a significant increase in immature mortality in s-methoprene-treated pools, suggesting that s-methoprene field trials based solely on emergence inhibition of pupae may underestimate the efficacy of this insecticide. PMID:17972627

Jeffery, Jason A L; Kay, Brian H; Ryan, Peter A

2007-10-01

439

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

PubMed Central

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 t