26 research outputs found
Composite Adaptive Lyapunov-Based Deep Neural Network (Lb-DNN) Controller
Recent advancements in adaptive control have equipped deep neural network
(DNN)-based controllers with Lyapunov-based adaptation laws that work across a
range of DNN architectures to uniquely enable online learning. However, the
adaptation laws are based on tracking error, and offer convergence guarantees
on only the tracking error without providing conclusions on the parameter
estimation performance. Motivated to provide guarantees on the DNN parameter
estimation performance, this paper provides the first result on composite
adaptation for adaptive Lyapunov-based DNN controllers, which uses the Jacobian
of the DNN and a prediction error of the dynamics that is computed using a
novel method involving an observer of the dynamics. A Lyapunov-based stability
analysis is performed which guarantees the tracking, observer, and parameter
estimation errors are uniformly ultimately bounded (UUB), with stronger
performance guarantees when the DNN's Jacobian satisfies the persistence of
excitation (PE) condition. Comparative simulation results demonstrate a
significant performance improvement with the developed composite adaptive
Lb-DNN controller in comparison to the tracking error-based Lb-DNN
First reported case of fatal tuberculosis in a wild African elephant with past human-wildlife contact
Tuberculosis is emerging/re-emerging in captive elephant populations, where it causes morbidity and deaths, although no case of TB in wild African elephants has been reported. In this paper we report the first case of fatal TB in an African elephant in the wild. The infection with Mycobacterium tuberculosis was confirmed by post-mortem and histological examinations of a female sub-adult elephant aged >12 years that died in Tsavo East National Park, Kenya, while under treatment. This case is unique in that during its lifetime the elephant had contact with both humans and wild elephants. The source of the infection was unclear because the elephant could have acquired the infection in the orphanage or in the wild. However, our results show that wild elephants can maintain human TB in the wild and that the infection can be fata
Cohort profile : the Kilifi vaccine monitoring study
The Kilifi Vaccine Monitoring Study (KiVMS) is a long-term continuous cohort study set up to investigate effectiveness, impact, coverage, safety and indirect vaccine effects by recruiting birth cohorts and, where applicable, cohorts of older and adults. It is based in the area covered by the Kilifi Health and Demographic Surveillance System, Kilifi, Kenya, and currently has records of 33 962 children in the birth cohort database. A major strength of KiVMS is its unique integration of a vaccine registry, a morbidity surveillance system and the largest health and demographic surveillance system (HDSS) in Africa
Effect of 10-valent pneumococcal conjugate vaccine on the incidence of radiologically-confirmed pneumonia and clinically-defined pneumonia in Kenyan children: an interrupted time-series analysis
BACKGROUND: Pneumococcal conjugate vaccines (PCV) are highly protective against invasive pneumococcal disease caused by vaccine serotypes, but the burden of pneumococcal disease in low-income and middle-income countries is dominated by pneumonia, most of which is non-bacteraemic. We examined the effect of 10-valent PCV on the incidence of pneumonia in Kenya. METHODS: We linked prospective hospital surveillance for clinically-defined WHO severe or very severe pneumonia at Kilifi County Hospital, Kenya, from 2002 to 2015, to population surveillance at Kilifi Health and Demographic Surveillance System, comprising 45 000 children younger than 5 years. Chest radiographs were read according to a WHO standard. A 10-valent pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PCV10) was introduced in Kenya in January, 2011. In Kilifi, there was a three-dose catch-up campaign for infants (aged <1 year) and a two-dose catch-up campaign for children aged 1-4 years, between January and March, 2011. We estimated the effect of PCV10 on the incidence of clinically-defined and radiologically-confirmed pneumonia through interrupted time-series analysis, accounting for seasonal and temporal trends. FINDINGS: Between May 1, 2002 and March 31, 2015, 44 771 children aged 2-143 months were admitted to Kilifi County Hospital. We excluded 810 admissions between January and March, 2011, and 182 admissions during nurses' strikes. In 2002-03, the incidence of admission with clinically-defined pneumonia was 2170 per 100 000 in children aged 2-59 months. By the end of the catch-up campaign in 2011, 4997 (61·1%) of 8181 children aged 2-11 months had received at least two doses of PCV10 and 23 298 (62·3%) of 37 416 children aged 12-59 months had received at least one dose. Across the 13 years of surveillance, the incidence of clinically-defined pneumonia declined by 0·5% per month, independent of vaccine introduction. There was no secular trend in the incidence of radiologically-confirmed pneumonia over 8 years of study. After adjustment for secular trend and season, incidence rate ratios for admission with radiologically-confirmed pneumonia, clinically-defined pneumonia, and diarrhoea (control condition), associated temporally with PCV10 introduction and the catch-up campaign, were 0·52 (95% CI 0·32-0·86), 0·73 (0·54-0·97), and 0·63 (0·31-1·26), respectively. Immediately before PCV10 was introduced, the annual incidence of clinically-defined pneumonia was 1220 per 100 000; this value was reduced by 329 per 100 000 at the point of PCV10 introduction. INTERPRETATION: Over 13 years, admissions to Kilifi County Hospital for clinically-defined pneumonia decreased sharply (by 27%) in association with the introduction of PCV10, as did the incidence of radiologically-confirmed pneumonia (by 48%). The burden of hospital admissions for childhood pneumonia in Kilifi, Kenya, has been reduced substantially by the introduction of PCV10. FUNDING: Gavi, The Vaccine Alliance and Wellcome Trust
Explaining the host-finding behavior of blood-sucking insects: computerized simulation of the effects of habitat geometry on tsetse fly movement
BACKGROUND: Male and female tsetse flies feed exclusively on vertebrate blood. While doing so they can transmit the diseases of sleeping sickness in humans and nagana in domestic stock. Knowledge of the host-orientated behavior of tsetse is important in designing bait methods of sampling and controlling the flies, and in understanding the epidemiology of the diseases. For this we must explain several puzzling distinctions in the behavior of the different sexes and species of tsetse. For example, why is it that the species occupying savannahs, unlike those of riverine habitats, appear strongly responsive to odor, rely mainly on large hosts, are repelled by humans, and are often shy of alighting on baits?
METHODOLOGY/PRINCIPLE FINDINGS: A deterministic model that simulated fly mobility and host-finding success suggested that the behavioral distinctions between riverine, savannah and forest tsetse are due largely to habitat size and shape, and the extent to which dense bushes limit occupiable space within the habitats. These factors seemed effective primarily because they affect the daily displacement of tsetse, reducing it by up to ,70%. Sex differences in behavior are explicable by females being larger and more mobile than males.
CONCLUSION/SIGNIFICANCE: Habitat geometry and fly size provide a framework that can unify much of the behavior of all sexes and species of tsetse everywhere. The general expectation is that relatively immobile insects in restricted habitats tend to be less responsive to host odors and more catholic in their diet. This has profound implications for the optimization of bait technology for tsetse, mosquitoes, black flies and tabanids, and for the epidemiology of the diseases they transmit
A Latex Agglutination Test for Capripoxvirus
The gene Q13L coding for the Capripoxvirus group specific structural protein P32 was expressed in Escherichia coli using plasmid pGEX-2T as a fusion protein with glutathione-s-transferase and purified on glutathione sepharose affinity chromatography column. The protein was then employed for diagnosis of sheeppox, goatpox and lumpyskin
disease, by a latex agglutination test (LAT) using the purified P32 antigen and guinea pig detector antiserum raised against the P32 antigen. The LAT and virus neutralization test (VNT) were used to screen one hundred livestock field sera for antibodies to Capripoxvirus, in comparison the LAT was simpler, rapid and 23% more sensitive than the
VNT. In addition the LAT was found to be specific for Carpripoxvirus because it did not pick antibodies to Orthopoxvirus and Parapoxvirus. The LA test can be taken for a simple and quick diagnostic tool for primary screening of Carpripoxvirus infection and will reduce the reliance of diagnostic laboratories on tissue culture facilities. Keywords: Carpripox, latex agglutination test, attachment gene J. Trop. Microbiol. Biotechnol. Vol. 3 (2) 2007: pp. 36-4
First reported case of fatal tuberculosis in a wild African elephant with past human-wildlife contact
Tuberculosis is emerging/re-emerging in captive elephant populations, where it causes morbidity and deaths, although no case of TB in wild African elephants has been reported. In this paper we report the first case of fatal TB in an African elephant in the wild. The infection with Mycobacterium tuberculosis was confirmed by post-mortem and histological examinations of a female sub-adult elephant aged >12 years that died in Tsavo East National Park, Kenya, while under treatment. This case is unique in that during its lifetime the elephant had contact with both humans and wild elephants. The source of the infection was unclear because the elephant could have acquired the infection in the orphanage or in the wild. However, our results show that wild elephants can maintain human TB in the wild and that the infection can be fatal.Peer reviewe
COMBINATION OF BLEACH AND FLOURESCENT MICROSCOPY: A MILESTONE IN THE DIAGNOSIS OF SMEAR NEGATIVE TUBERCULOSIS
ABSTRACTBackground: The reliability of direct smear microscopy for diagnosis of tuberculosis has frequentlybeen questioned due to low sensitivity. Treatment of sputum with sodium hypochlorite (NaOCI)has been used to increase sensitivity in many settings. However, no study has established the effectof NaOCI on fl uorescent microscopy.Objective: To establish whether NaOCI concentration method enhances positivity of fl uorescentmicroscopy smear negative sputum for diagnosis of tuberculosis.Design: A prospective study.Setting: Mbagathi District Hospital and Centre for Respiratory Diseases Research, Kenya MedicalResearch Institute.Results: Forty fi ve (22%) specimens were culture positive. Fluorescent microscopy sensitivitywas 28.9% and 22.2% after centrifugation and sedimentation with 3.5% NaOCI, respectively (P >0.05). Sensitivity was 24.4% and 17.8% after centrifugation and sedimentation with 5% NaOCI,respectively (P > 0.05). Although there was no statistical signifi cance difference between the twoNaOCI concentration methods, 3.5% NaOCI with centrifugation indicated a higher yield.Conclusion: Use of NaOCI signifi cantly enhances positivity of smear negative sputum for diagnosisof tuberculosis when used with fl uorescent microscopy. This approach could be recommendedfor screening all tuberculosis suspects especially in settings with potential smear negativetuberculosis
Clinical and pathological findings in piglets infected with Trypoanosoma simiae tsavo
No Abstract. BAHPA Vol. 54 (3) 2006: pp. 176-18
Clinical and pathological findings in piglets infected with Trypoanosoma simiae tsavo
No Abstract. BAHPA Vol. 54 (3) 2006: pp. 176-18