112 research outputs found
Temporal integration for robust detection of distant moving objects observed by a mobile camera
The detection of moving objects in an outdoor and disturbed scene observed by a mobile camera is a difficult problem, whos e
solution requires to take into account more than two successive images to achieve robustness . In this paper we present two ways
to carry out this temporal integration in the motion detection process : first, the use of long temporal observations for the decisio n
criteria, secondly the implementation of a prediction module . These observations are usually get from temporal filtering at differen t
temporal scales . Prediction of mobile objects is iteratively updated using current detection results, but also controls the detectio n
process of the following instant . When using a static sensor, we have only to consider successive images, but if the sensor itself i s
moving, we need previously to compensate the apparent motion of the image . The methods that we have developped are teste d
on various real images, and their interest is evaluated .La dĂ©tection d'objets mobiles dans une scĂšne extĂ©rieure perturbĂ©e Ă partir d'une camĂ©ra embarquĂ©e est un problĂšme difficile, dont la solution ne peut ĂȘtre robuste qu'avec un intervalle temporel d'analyse supĂ©rieur Ă deux images consĂ©cutives. on envisage ici deux façons d'intĂ©grer le temps dans le processus de dĂ©tection : d'une part l'utilisation d'observations temporelles longues pour la dĂ©cision, d'autre part la mise en oeuvre d'un module de prĂ©diction. Ces observations sont typiquement construites Ă partir d'un filtrage temporel de la sĂ©quence d'images Ă diffĂ©rentes Ă©chelles de temps. La prĂ©diction, qui concerne les objets dĂ©tectĂ©s, est mise Ă jour incrĂ©mentalement Ă l'aide des rĂ©sultats de la dĂ©tection Ă l'instant courant, mais elle permet aussi de guider la dĂ©tection lors de l'instant suivant. Quand la camĂ©ra est fixe, il suffit de considĂ©rer les images successives, mais dans le cas d'une camĂ©ra mobile, il est nĂ©cessaire de compenser prĂ©alablement le mouvement apparent de l'image. Les mĂ©thodes prĂ©sentĂ©es dans cet article sont validĂ©es sur plusieurs sĂ©quences rĂ©elles et l'apport des diffĂ©rentes solutions est Ă©valuĂ©
Measuring a population of spin waves from the electrical noise of an inductively coupled antenna
We study how a population of spin waves can be characterized from the
analysis of the electrical microwave noise delivered by an inductive antenna
placed in its vicinity. The measurements are conducted on a synthetic
antiferromagnetic thin stripe covered by a micron-sized antenna that feeds a
spectrum analyser after amplification. The antenna noise contains two
contributions. The population of incoherent spin waves generates a fluctuating
field that is sensed by the antenna: this is the "magnon noise". The antenna
noise also contains the contribution of the electronic fluctuations: the
Johnson-Nyquist noise. The latter depends on all impedances within the
measurement circuit; this includes the antenna self-inductance. As a result,
the electronic noise contains information about the magnetic susceptibility,
though it does not inform on the absolute amplitude of the magnetic
fluctuations. For micrometer-sized systems at thermal equilibrium, the
electronic noise dominates and the pure magnon noise cannot be determined. If
in contrast the spinwave bath is not at thermal equilibrium with the
measurement circuit, and if the spinwave population can be changed then one
could measure a mode-resolved effective magnon temperature provided specific
precautions are implemented
A Bundle of Services Increased Ascertainment of Tuberculosis among HIV-Infected Individuals Enrolled in a HIV Cohort in Rural Sub-Saharan Africa
OBJECTIVES: To report on trends of tuberculosis ascertainment
among HIV patients in a rural HIV cohort in Tanzania, and
assessing the impact of a bundle of services implemented in
December 2012, consisting of three components:(i)integration of
HIV and tuberculosis services; (ii)GeneXpert for tuberculosis
diagnosis; and (iii)electronic data collection. DESIGN:
Retrospective cohort study of patients enrolled in the Kilombero
Ulanga Antiretroviral Cohort (KIULARCO), Tanzania.). METHODS:
HIV patients without prior history of tuberculosis enrolled in
the KIULARCO cohort between 2005 and 2013 were included.Cox
proportional hazard models were used to estimate rates and
predictors of tuberculosis ascertainment. RESULTS: Of 7114 HIV
positive patients enrolled, 5123(72%) had no history of
tuberculosis. Of these, 66% were female, median age was 38
years, median baseline CD4+ cell count was 243 cells/microl, and
43% had WHO clinical stage 3 or 4. During follow-up, 421
incident tuberculosis cases were notified with an estimated
incidence of 3.6 per 100 person-years(p-y)[95% confidence
interval(CI)3.26-3.97]. The incidence rate varied over time and
increased significantly from 2.96 to 43.98 cases per 100 p-y
after the introduction of the bundle of services in December
2012. Four independent predictors of tuberculosis ascertainment
were identified:poor clinical condition at baseline (Hazard
Ratio (HR) 3.89, 95% CI 2.87-5.28), WHO clinical stage 3 or 4
(HR 2.48, 95% CI 1.88-3.26), being antiretroviralnaive (HR 2.97,
95% CI 2.25-3.94), and registration in 2013(HR 6.07, 95% CI
4.39-8.38). CONCLUSION: The integration of tuberculosis and HIV
services together with comprehensive electronic data collection
and use of GeneXpert increased dramatically the ascertainment of
tuberculosis in this rural African HIV cohort
Body mass index trends and its impact of under and overweight on outcome among PLHIV on antiretroviral treatment in rural Tanzania: a prospective cohort study
INTRODUCTION: Increased body weight is an important risk factor for cardiovascular disease and is increasingly reported as a health problem in people living with HIV (PLHIV). There is limited data from rural sub-Saharan Africa, where malnutrition usually presents with both over- and undernutrition. We aimed to determine the prevalence and risk factors of underweight and overweight/obesity in PLHIV enrolled in a cohort in rural Tanzania before the introduction of integrase inhibitors. METHODS: This nested study of the prospective Kilombero and Ulanga Antiretroviral Cohort included adults aged â„19 years initiated on antiretroviral therapy between 01/2013 and 12/2018 with follow-up through 06/2019. Body Mass Index (BMI) was classified as underweight (<18.5 kg/m2), normal (18.5-24.9 kg/m2), or overweight/obese (â„25.0 kg/m2). Stratified piecewise linear mixed models were used to assess the association between baseline characteristics and follow-up BMI. Cox proportional hazard models were used to assess the association between time-updated BMI and death/loss to follow-up (LTFU). RESULTS: Among 2,129 patients, 22,027 BMI measurements (median 9 measurements: interquartile range 5-15) were analysed. At baseline, 398 (19%) patients were underweight and 356 (17%) were overweight/obese. The majority of patients were female (n = 1249; 59%), and aged 35-44 years (779; 37%). During the first 9 months, for every three additional months on antiretroviral therapy, BMI increased by 2% (95% confidence interval 1-2%, p<0.0001) among patients underweight at baseline and by 0.7% (0.5-0.6%, p 2 times the hazard of death/LTFU compared to participants with normal BMI. CONCLUSION: We found a double burden of malnutrition, with underweight being an independent predictor of mortality. Monitoring and measures to address both states of malnutrition among PLHIV should be integrated into routine HIV care
Cryptococcal Antigenemia in Immunocompromised Human Immunodeficiency Virus Patients in Rural Tanzania: A Preventable Cause of Early Mortality
Background. Cryptococcal meningitis is a leading cause of death
in people living with human immunodeficiency virus
(HIV)/acquired immune deficiency syndrome. The World Health
Organizations recommends pre-antiretroviral treatment (ART)
cryptococcal antigen (CRAG) screening in persons with CD4 below
100 cells/microL. We assessed the prevalence and outcome of
cryptococcal antigenemia in rural southern Tanzania. Methods. We
conducted a retrospective study including all ART-naive adults
with CD4 <150 cells/microL prospectively enrolled in the
Kilombero and Ulanga Antiretroviral Cohort between 2008 and
2012. Cryptococcal antigen was assessed in cryopreserved pre-ART
plasma. Cox regression estimated the composite outcome of death
or loss to follow-up (LFU) by CRAG status and fluconazole use.
Results. Of 750 ART-naive adults, 28 (3.7%) were CRAG-positive,
corresponding to a prevalence of 4.4% (23 of 520) in CD4 <100
and 2.2% (5 of 230) in CD4 100-150 cells/microL. Within 1 year,
75% (21 of 28) of CRAG-positive and 42% (302 of 722) of
CRAG-negative patients were dead or LFU (P<.001), with no
differences across CD4 strata. Cryptococcal antigen positivity
was an independent predictor of death or LFU after adjusting for
relevant confounders (hazard ratio [HR], 2.50; 95% confidence
interval [CI], 1.29-4.83; P = .006). Cryptococcal meningitis
occurred in 39% (11 of 28) of CRAG-positive patients, with
similar retention-in-care regardless of meningitis diagnosis (P
= .8). Cryptococcal antigen titer >1:160 was associated with
meningitis development (odds ratio, 4.83; 95% CI, 1.24-8.41; P =
.008). Fluconazole receipt decreased death or LFU in
CRAG-positive patients (HR, 0.18; 95% CI, .04-.78; P = .022).
Conclusions. Cryptococcal antigenemia predicted mortality or LFU
among ART-naive HIV-infected persons with CD4 <150
cells/microL, and fluconazole increased survival or
retention-in-care, suggesting that targeted pre-ART CRAG
screening may decrease early mortality or LFU. A CRAG screening
threshold of CD4 <100 cells/microL missed 18% of
CRAG-positive patients, suggesting guidelines should consider a
higher threshold
Prevention of mother-to-child transmission of HIV Option B+ cascade in rural Tanzania: The One Stop Clinic model
BACKGROUND: Strategies to improve the uptake of Prevention of
Mother-To-Child Transmission of HIV (PMTCT) are needed. We
integrated HIV and maternal, newborn and child health services
in a One Stop Clinic to improve the PMTCT cascade in a rural
Tanzanian setting. METHODS: The One Stop Clinic of Ifakara
offers integral care to HIV-infected pregnant women and their
families at one single place and time. All pregnant women and
HIV-exposed infants attended during the first year of Option B+
implementation (04/2014-03/2015) were included. PMTCT was
assessed at the antenatal clinic (ANC), HIV care and labour
ward, and compared with the pre-B+ period. We also characterised
HIV-infected pregnant women and evaluated the MTCT rate.
RESULTS: 1,579 women attended the ANC. Seven (0.4%) were known
to be HIV-infected. Of the remainder, 98.5% (1,548/1,572) were
offered an HIV test, 94% (1,456/1,548) accepted and 38 (2.6%)
tested HIV-positive. 51 were re-screened for HIV during late
pregnancy and one had seroconverted. The HIV prevalence at the
ANC was 3.1% (46/1,463). Of the 39 newly diagnosed women, 35
(90%) were linked to care. HIV test was offered to >98% of
ANC clients during both the pre- and post-B+ periods. During the
post-B+ period, test acceptance (94% versus 90.5%, p<0.0001)
and linkage to care (90% versus 26%, p<0.0001) increased. Ten
additional women diagnosed outside the ANC were linked to care.
82% (37/45) of these newly-enrolled women started antiretroviral
treatment (ART). After a median time of 17 months, 27% (12/45)
were lost to follow-up. 79 women under HIV care became pregnant
and all received ART. After a median follow-up time of 19
months, 6% (5/79) had been lost. 5,727 women delivered at the
hospital, 20% (1,155/5,727) had unknown HIV serostatus. Of
these, 30% (345/1,155) were tested for HIV, and 18/345 (5.2%)
were HIV-positive. Compared to the pre-B+ period more women were
tested during labour (30% versus 2.4%, p<0.0001). During the
study, the MTCT rate was 2.2%. CONCLUSIONS: The implementation
of Option B+ through an integrated service delivery model
resulted in universal HIV testing in the ANC, high rates of
linkage to care, and MTCT below the elimination threshold.
However, HIV testing in late pregnancy and labour, and retention
during early ART need to be improved
Immune reconstitution inflammatory syndrome associated with Kaposi sarcoma: higher incidence and mortality in Africa than in the UK.
OBJECTIVES: To assess the incidence, predictors, and outcomes of Kaposi sarcoma-associated paradoxical immune reconstitution inflammatory syndrome (KS-IRIS) in antiretroviral therapy (ART)-naive HIV-infected patients with Kaposi sarcoma initiating ART in both well resourced and limited-resourced settings. DESIGN: Pooled analysis of three prospective cohorts of ART-naive HIV-infected patients with Kaposi sarcoma from sub-Saharan Africa (SSA) and one from the UK. METHODS: KS-IRIS case definition was standardized across sites. Cox regression and Kaplan-Meier survival analysis were used to identify the incidence and predictors of KS-IRIS and Kaposi sarcoma-associated mortality. RESULTS: Fifty-eight of 417 (13.9%) eligible individuals experienced KS-IRIS with an incidence 2.5 times higher in the African vs. European cohorts (P=0.001). ART alone as initial Kaposi sarcoma treatment (hazard ratio 2.97, 95% confidence interval (CI) 1.02-8.69); T1 Kaposi sarcoma stage (hazard ratio 2.96, 95% CI 1.26-6.94); and plasma HIV-1 RNA more than 5 logââ copies/ml (hazard ratio 2.14, 95% CI 1.25-3.67) independently predicted KS-IRIS at baseline. Detectable plasma Kaposi sarcoma-associated herpes virus (KSHV) DNA additionally predicted KS-IRIS among the 259 patients with KSHV DNA assessed (hazard ratio 2.98, 95% CI 1.23-7.19). Nineteen KS-IRIS patients died, all in SSA. Kaposi sarcoma mortality was 3.3-fold higher in Africa, and was predicted by KS-IRIS (hazard ratio 19.24, CI 7.62-48.58), lack of chemotherapy (hazard ratio 2.35, 95% CI 1.09-5.05), pre-ART CD4 cell count less than 200 cells/ÎŒl (hazard ratio 2.04, 95% CI 0.99-4.2), and detectable baseline KSHV DNA (hazard ratio 2.12, 95% CI 0.94-4.77). CONCLUSION: KS-IRIS incidence and mortality are higher in SSA than in the UK. This is largely explained by the more advanced Kaposi sarcoma disease and lower chemotherapy availability. KS-IRIS is a major contributor to Kaposi sarcoma-associated mortality in Africa. Our results support the need to increase awareness on KS-IRIS, encourage earlier presentation, referral and diagnosis of Kaposi sarcoma, and advocate on access to systemic chemotherapy in Africa
Absence of hepatitis delta infection in a large rural HIV cohort in Tanzania
OBJECTIVES: The epidemiological and clinical determinants of
hepatitis delta virus (HDV) infection in Sub-Saharan Africa are
ill-defined. The prevalence of HDV infection was determined in
HIV/hepatitis B virus (HBV) co-infected individuals in rural
Tanzania. METHODS: All hepatitis B virus (HBV)-infected adults
under active follow-up in the Kilombero and Ulanga
Antiretroviral Cohort (KIULARCO) were screened for anti-HDV
antibodies. For positive samples, a second serological test and
nucleic acid amplification were performed. Demographic and
clinical characteristics at initiation of antiretroviral therapy
(ART) were compared between anti-HDV-negative and positive
patients. RESULTS: Among 222 HIV/HBV co-infected patients on
ART, 219 (98.6%) had a stored serum sample available and were
included in the study. Median age was 37 years, 55% were female,
46% had World Health Organization stage III/IV HIV disease, and
the median CD4 count was 179 cells/mul. The prevalence of
anti-HDV positivity was 5.0% (95% confidence interval 2.8-8.9%).
There was no significant predictor of anti-HDV positivity. HDV
could not be amplified in any of the anti-HDV-positive patients
and the second serological test was negative in all of them.
CONCLUSIONS: No confirmed case of HDV infection was found among
over 200 HIV/HBV co-infected patients in Tanzania. As
false-positive serology results are common, screening results
should be confirmed with a second test
- âŠ