Joint estimation of CD4+ cell progression and survival in untreated individuals with HIV-1 infection

Objective: We compiled the largest dataset of seroconverter cohorts to date from 25 countries across Africa, North America, Europe, and Southeast/East (SE/E) Asia to simultaneously estimate transition rates between CD4+ cell stages and death, in antiretroviral therapy (ART)-naive HIV-1-infected individuals. Design: A hidden Markov model incorporating a misclassification matrix was used to represent natural short-term fluctuations and measurement errors in CD4+ cell counts. Covariates were included to estimate the transition rates and survival probabilities for each subgroup. Results: The median follow-up time for 16 373 eligible individuals was 4.1 years (interquartile range 1.7–7.1), and the mean age at seroconversion was 31.1 years (SD 8.8). A total of 14 525 individuals had recorded CD4+ cell counts pre-ART, 1885 died, and 6947 initiated ART. Median (interquartile range) survival for men aged 20 years at seroconversion was 13.0 (12.4–13.4), 11.6 (10.9–12.3), and 8.3 years (7.9–8.9) in Europe/North America, Africa, and SE/E Asia, respectively. Mortality rates increase with age (hazard ratio 2.22, 95% confidence interval 1.84–2.67 for >45 years compared with <25 years) and vary by region (hazard ratio 2.68, 1.75–4.12 for Africa and 1.88, 1.50–2.35 for Asia compared with Europe/North America). CD4+ cell decline was significantly faster in Asian cohorts compared with Europe/North America (hazard ratio 1.45, 1.36–1.54). Conclusion: Mortality and CD4+ cell progression rates exhibited regional and age-specific differences, with decreased survival in African and SE/E Asian cohorts compared with Europe/North America and in older age groups. This extensive dataset reveals heterogeneities between regions and ages, which should be incorporated into future HIV models

Effects of Snail Density on Growth, Reproduction and Survival of Biomphalaria alexandrina Exposed to Schistosoma mansoni

The effects of snail density on Biomphalaria alexandrina parasitized with Schistosoma mansoni were investigated. Laboratory experiments were used to quantify the impact of high density on snail growth, fecundity, and survival. Density-dependent birth rates of snails were determined to inform mathematical models, which, until now, have assumed a linear relationship between density and fecundity. The experiments show that the rate of egg-laying followed a negative exponential distribution with increasing density and this was significantly affected by exposure to parasitic infection. High density also affected the weight of snails and survival to a greater degree than exposure to parasitic infection. Although snail growth rates were initially constrained by high density, they retained the potential for growth suggesting a reversible density-dependent mechanism. These experimental data can be used to parameterise models and confirm that snail populations are regulated by nonlinear density-dependent mechanisms

Brownian rectifiers in the presence of temporally asymmetric unbiased forces

The efficiency of energy transduction in a temporally asymmetric rocked ratchet is studied. Time asymmetry favours current in one direction and suppresses it in the opposite direction due to which large efficiency ~ 50% is readily obtained. The spatial asymmetry in the potential together with system inhomogeneity may help in further enhancing the efficiency. Fine tuning of system parameters considered leads to multiple current reversals even in the adiabatic regime

THERAPEUTIC MANAGEMENT OF PRAVAHIKA (AMOEBIC DYSENTERY) THROUGH AYURVEDIC REGIMEN: A CASE STUDY

Hurry, worry and curry are the three factors which causes intestinal upsets frequently and leads to gastrointestinal problems in modern life. Pravahika (Amoebic dysentery) is also one of the important and oftenly occurring Vyadhis of Annavaha and Pureeshvaha Srotasas in current time. Pravahika is the Pakwasahayagata kaphajavikara with symptoms of Sarakta mala, Sapravahana mala, Sakapha mala, Daah, Jwara, Bhrama Daurbalya, Anannabhilsha, Sweda and Trishna. A case report of a patient with a history of loose motion with mucous discharge for the 6 months visited Ayurveda OPD, is presented in this study. Routine stool examination, blood glucose, serum lipid profile and liver function test were performed. The patient was treated with Ayurvedic medicine Kutajghan vati (1 gm), Bilvadi churna with Takra (6 gm) and, Chitrakadi Gutika (250 mg) in divided doses for 1 month. The patient was followed up for every 7th day and there was significant improvement in the clinical features after 1 month of treatment with the Ayurvedic medicines. There were no side effects reported. This case study demonstrates the therapeutic efficacy of Bilvadi churna, Kutajghan vati and Chitrakadi Gutika in the rapid management of Pravahika.

Investigation of the Saturation of Elemental Concentration in the Depth Profile of Low Energy Silver Ion Implants in Silicon

For the efficient absorption of light in a broad wavelength band, Si photovoltaic devices require a high concentration of metal atoms at a shallow depth up to a few 10s of nm in the Si substrates. Low energy (< 50 keV) implantation of Ag ions in Si is one of the most suitable synthesis steps to facilitate the formation of these metal nanoclusters at the shallow depths in Si. However, during the low energy implantation of the heavy ions, one of the unintended consequences is the sputtering of target atoms particularly if the target is made of lower Z materials such as Si. In this study, we have investigated the re-distribution of atoms in the target layers due to the surface sputtering effects from 50 keV Ag ion implantation in Si substrates. Initially, the implant profile was estimated with the widely used static simulation code, theStopping and Range of Ions in Matter (SRIM). However, it’s simulation routine lacks any consideration of the fluence dependent evolution of the target material. Therefore, we have explored the use of another ion-solid interaction code T-DYN, which considers the dynamic changes in the thickness and/or composition of the target material during the implantation process. For 50 keV Ag ion implantation in Si, the T-DYN simulation predicts the Ag ion depth profile reaches a maximum or saturation in the concentration at a critical ion fluence of ~7×1016 atoms/cm2, whereas for a more heavier element like Au, similar saturation in the concentration is predicted at a relatively lower fluence of ~4×1016 atoms/cm2. The depth profiles of the implanted Ag atoms extracted from experiments utilizing the Rutherford Backscattering Spectrometry and X-ray Photoelectron Spectroscopy characterization techniques show asymmetric distributions with the position of peak concentration depth gradually moving towards the Si surface with increasing implant ion fluence. Once the implantation ion fluence reached a critical value, the peak value of the elemental concentration is seen saturated similar to the predictions from T-DYN simulations

Key issues in the persistence of poliomyelitis in Nigeria: a case-control study

Background The completion of poliomyelitis eradication is a global emergency for public health. In 2012, more than 50% of the world’s cases occurred in Nigeria following an unanticipated surge in incidence. We aimed to quantitatively analyse the key factors sustaining transmission of poliomyelitis in Nigeria and to calculate clinical effi cacy estimates for the oral poliovirus vaccines (OPV) currently in use. Methods We used acute fl accid paralysis (AFP) surveillance data from Nigeria collected between January, 2001, and December, 2012, to estimate the clinical effi cacies of all four OPVs in use and combined this with vaccination coverage to estimate the eff ect of the introduction of monovalent and bivalent OPV on vaccine-induced serotype-specifi c population immunity. Vaccine effi cacy was determined using a case-control study with CIs based on bootstrap resampling. Vaccine effi cacy was also estimated separately for north and south Nigeria, by age of the children, and by year. Detailed 60-day follow-up data were collected from children with confi rmed poliomyelitis and were used to assess correlates of vaccine status. We also quantitatively assessed the epidemiology of poliomyelitis and programme performance and considered the reasons for the high vaccine refusal rate along with risk factors for a given local government area reporting a case. Findings Against serotype 1, both monovalent OPV (median 32·1%, 95% CI 26·1–38·1) and bivalent OPV (29·5%, 20·1–38·4) had higher clinical effi cacy than trivalent OPV (19·4%, 16·1–22·8). Corresponding data for serotype 3 were 43·2% (23·1–61·1) and 23·8% (5·3–44·9) compared with 18·0% (14·1–22·1). Combined with increases in coverage, this factor has boosted population immunity in children younger than age 36 months to a record high (64–69% against serotypes 1 and 3). Vaccine effi cacy in northern states was estimated to be signifi cantly lower than in southern states (p≤0·05). The proportion of cases refusing vaccination decreased from 37–72% in 2008 to 21–51% in 2012 for routine and supplementary immunisation, and most caregivers cited ignorance of either vaccine importance or availability as the main reason for missing routine vaccinations (32·1% and 29·6% of cases, respectively). Multiple regression analyses highlighted associations between the age of the mother, availability of OPV at health facilities, and the primary source of health information and the probability of receiving OPV (all p<0·05). Interpretation Although high refusal rates, low OPV campaign awareness, and heterogeneous population immunity continued to support poliomyelitis transmission in Nigeria at the end of 2012, overall population immunity had improved due to new OPV formulations and improvements in programme delivery.Funding Bill & Melinda Gates Foundation Vaccine Modeling Initiative, Royal Society.Introduction In May, 2012, after more than 20 years of mass vaccination campaigns, the 65t

Asymmetric motion in a double-well under the action of zero-mean Gaussian white noise and periodic forcing

Residence times of a particle in both the wells of a double-well system, under the action of zero-mean Gaussian white noise and zero-averaged but temporally asymmetric periodic forcings, are recorded in a numerical simulation. The difference between the relative mean residence times in the two wells shows monotonic variation as a function of asymmetry in the periodic forcing and for a given asymmetry the difference becomes largest at an optimum value of the noise strength. Moreover, the passages from one well to the other become less synchronous at small noise strength as the asymmetry parameter (defined below) differs from zero, but at relatively larger noise strengths the passages become more synchronous with asymmetry in the field sweep. We propose that asymmetric periodic forcing (with zero mean) could provide a simple but sensible physical model for unidirectional motion in a symmetric periodic system aided by a symmetric Gaussian white noise.Comment: Appeared in PRE March 1997, figures available on reques