Parameter estimation and treatment optimization in a stochastic model for immunotherapy of cancer

Adoptive Cell Transfer therapy of cancer is currently in full development and mathematical modeling is playing a critical role in this area. We study a stochastic model developed by Baar et al. in 2015 for modeling immunotherapy against melanoma skin cancer. First, we estimate the parameters of the deterministic limit of the model based on biological data of tumor growth in mice. A Nonlinear Mixed Effects Model is estimated by the Stochastic Approximation Expectation Maximization algorithm. With the estimated parameters, we head back to the stochastic model and calculate the probability that the T cells all get exhausted during the treatment. We show that for some relevant parameter values, an early relapse is due to stochastic fluctuations (complete T cells exhaustion) with a non negligible probability. Then, focusing on the relapse related to the T cell exhaustion, we propose to optimize the treatment plan (treatment doses and restimulation times) by minimizing the T cell exhaustion probability in the parameter estimation ranges.Comment: major reorganisation of the paper and the reformulation of many substantial part

An Analysis of Long Run Determinants on Domestic Private Investment in Côte d'Ivoire

This study aims to model the long run determinants of domestic private investment in Côte d'Ivoire. Advanced econometric technique of Auto-Regressive Distributed Lag (ARDL) bounds testing approach is employed. Data from our study covers the period from 1970 to 2012. The results indicate that public investment, foreign direct investment, trade are the major determinants of short run and long run domestic private investment in Côte d'Ivoire while the real GDP growth rate and the interest rate are statistically insignificant. Thus, efforts should be geared to the development of necessary public investments in infrastructure such as supply constant electricity, good highways and elimination of the negative effects of external shocks engendered by the investment uncertainty and the deterioration of terms of trade

The question of gender discrimination in mortgage lending : a cross regional analysis

This study analyses the question of gender discrimination in mortgage lending. The federal fair lending regulations prohibit discrimination in granting credit with respect to race, gender, marital status, color, religion, age or receipt of public assistance. If discrimination exists in the mortgage market, it will keep creditworthy applicants from accessing home ownership, which represents the principal mean of capital and wealth accumulation. During the last two decades, studies regarding the problem of discrimination in mortgage credit have principally focused on the race issue. Race appeared to have, in most empirical studies, a significant impact on the outcome of mortgage application, with, in every instance, higher rejection rates for minorities than for non-minorities. Very few studies found interest in factors other than race affecting the distribution of mortgage loans. One of the variables mostly ignored in the analysis of discrimination in mortgage lending seems to be the one related to gender bias, raising the question whether sex discrimination in the mortgage lending market no longer represents a significant problem. The data used to examine the impact of gender on the mortgage lending market in this study were obtained from the 1996 Home Mortgage Disclosure Act (HMDA). Mortgage applications and outcomes in six Metropolitan Statistical Areas (MSAs) (Atlanta, GA; Austin TX; Memphis, TN; Boston, MA; Chicago, IL; and New York, NY) were analyzed, using a model of mortgage lending incorporating applicant and loan characteristics available in HMDA data. The study undertook both an MSA and a cross regional comparison (South-North), in order to account for socio-economic and cultural differences across MSAs and across regions. Due to some limitations of the HMDA data, particularly the unavailability of information about the applicant\u27s credit history, this study used a particular sampling method, the matched-pair method, similar but somewhat different from the one used by the Federal Reserve System. This statistical sampling method allowed the obtaining of exact matches of male and female applicants in terms of income levels and loan amounts requested. The results of probit regressions on the matched-pairs data sets were compared to those obtained using unmatched data sets in order to assess whether close matching of male and female applicants allows a better use of HMDA data as an instrument for fair lending regulations screenings. The comparative analysis of these results suggested that the matching process makes a sensible difference in the gender variable\u27s ability to predict mortgage lenders\u27 action. The empirical results indicated that once male and female applicants are exactly matched (in terms of income and loan amount requested), for any income group, little differentiation in the outcome of their mortgage loan application would be linked to gender. Moreover, the findings suggested that variables such as race, loan amount, income, mortgage type, and purpose could be predictors of mortgage lender\u27s decision only for low and median income applicantsIn contrast with several findings in the literature discussing racial discrimination in mortgage lending, the results of this study asserted that an applicant\u27s nonwhite status is not a deterrent to obtaining a mortgage loan. Moreover, the grouping of the observed MSAs into regions uncovers little geographical differences in mortgage decision. In sum, once a mortgage loan applicant is in the high-income group (over $75,000), none of the explanatory variables used in the present study seems to play any significant role into predicting lenders\u27 action

Food Insecurity and Psychological Well-Being Among Women Living with HIV/AIDS on Antiretroviral Therapy in the Alabama Black Belt

The objective of this research was to estimate the prevalence of food insecurity and determine if food insecurity is associated with psychological well-being among women living with HIV/AIDS. Survey data were collected from 268 women living with HIV/AIDS attending two clinics that provide medical and social support services to HIV-positive patients who live in 23 counties in Southeast Alabama. The results indicated that, using USDA food security scale, 54% of the women were food insecure. Multiple regression analysis results indicated that income, depressive symptoms, race, and participation in SNAP were significant predictors of food insecurity; employment and education were not statistically significant predictors. The overall model was significant at the 5% level reflecting the validity of the model. Based on these results, programs that address food insecurity should be a critical component of HIV/AIDS treatment in the Alabama Black Belt

Linke turbidity factors for several sites in Africa

International audienceThe Linke turbidity factor (TL) has been estimated at sixteen locations in Africa (9 stations in Egypt, 2 in Mozambique and Zimbabwe, 1 in Algeria, Tunisia and Zambia). An appropriate processing of time-series of measurements of daily sums of solar global radiation spanning several years provides mean values of TL for each month with a sufficient accuracy. Though limited to the Mediterranean area, Egypt and sub-tropical Southeastern part, this work greatly extends the knowledge on the clearness of the atmosphere in Africa, an area not much addressed in the literature. The relationship between TL and the climate is evidenced. TL is almost constant throughout the year close to the Mediterranean basin with values around 3.5. Stations located in the sub- tropical Southeastern part exhibit large variations of TL

Factors Associated with Belief in Conspiracies about HIV/AIDS among HIV-Positive African-American Patients

Abstract The purpose of this study is to examine factors associated with belief in conspiracies about HIV/AIDS among HIV-Positive African American patients. Survey data were collected from 256 African American patients living with HIV/AIDS attending two HIV clinics in Montgomery and Dothan, Alabama. The study used multiple regression analysis to examine how sociodemographic factors contribute to belief in conspiracies about HIV/AIDS. Education and age were significantly related to belief in conspiracies about HIV/AIDS among men and women. Beliefs in conspiracies about HIV/AIDS may be a barrier to HIV prevention among African Americans. Public health officials should work toward obtaining the trust of African Americans by addressing the existing discrimination within the health care system and acknowledging the existence of HIV/AIDS conspiracy beliefs. Conspiracies about HIV/AIDS may be a manifestation to African Americans’ mistrust of the U.S. government and the health system. Keywords: HIV/AIDS, African Americans, Conspiracy Belief

Toxicite des extraits aqueux de azadirachta indica a. juss et de Jatropha curcas L. sur Plutella xylostella (L.) (lepidoptera : plutellidae) par contact

La teigne du chou Plutella xylostella (Linné) (Lepidoptera : Plutellidae) est le principal insecte nuisible des crucifères dans les régions  tropicales et subtropicales. Les larves de ce Lépidoptère sont défoliatrices et peuvent causer des pertes importantes de production malgré l’application des  pesticides. L’objectif de cette étude est d’évaluer l’effet toxique par contact des extraits aqueux de neem (Azadirachta indica) et de Jatropha (Jatropha curcas) sur les larves de Plutella xylostella au stade L2 au laboratoire. Cette toxicité des extraits aqueux de poudres de grains de neem (41,5 g/L ; 25,9 g/L ; 10,3 g/L) et de jatropha (59,1 g/L ; 36,9 g/L ; 14,7 g/L) et de pâtes de feuilles neem et de jatropha à différents concentrations a été évaluée par la détermination des CL50 en 24 heures et par la toxicité de chaque traitement au bout de 72 heures. Les résultats ont montré que les extraits aqueux de poudres de grains, de Azadirachta indica 41,5 g/L et de Jatropha curcas 59,1 g/L ont été plus toxiques que les insecticides Décis et Cypercal. Par ailleurs, les extraits aqueux, de pâtes de feuilles de jatropha 67 g/L et de feuilles de Azadirachta indica 67 g/L ont une toxicité similaire au Décis et au Cypercal. Ces extraits aqueux de Azadirachta indica et de Jatropha curcas peuvent donc substituer les pesticides Décis et Cypercal dans la lutte contre Plutella xylostella. Mots clés : Azadirhacta indica, Jatropha curcas, extraits aqueux, Plutella xylostella, toxicité   English Title: Contact toxicity of aqueous extracts of Azadirachta Indica A. Juss and Jatropha Curcas L. on Plutella Xylostella (L.) (Lepidoptera: Plutellidae) Cabbage moth Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae) is a major pest of crucifers in the tropics and subtropics. Their larvae feed on cabbage and reduced cabbage yield despite the application of pesticides. The objective of this study was to determine the contact toxicity effect of aqueous extracts of Azadirachta indica and Jatropha curcas on the second instar larvae of P. xylostella. The toxicity of the various treatments of Azadirachta indica and Jatropha curcas seeds and leaves powders aqueous extracts were evaluated by determining the LC50 on 24 hours and by the toxicity effect of each treatment after 72 hours. The results showed that the seeds  powders aqueous extracts of Azadirachta indica 41.5 g/L and of Jatropha curcas 59.1 g / L were more toxic than the pesticides Decis and Cypercal on Plutella xylostella. Moreover, Jatropha curcas and Azadirachta indica leaves aqueous extracts 67 g / L have similar toxicity with Decis and Cypercal. The aqueous extracts of Azadirachta indica and Jatropha curcas can be used against Plutella xylostella. Keywords: Azadirhacta indica, Jatropha curcas, aqueous extracts, Plutella xylostella, toxicity

Using reduced data sets ISCCP-B2 from the Meteosat satellites to assess surface solar irradiance

International audienceThis paper explores the capabilities of a combination of the reduced data set ISCCP-B2 from the Meteosat satellites and the recently developed method Heliosat-2 to assess the daily mean of the surface solar irradiance at any geographical site in Europe and Africa. Firstly, we discuss the implementation of the method Heliosat-2. Secondly, B2-derived irradiances are compared to coincident measurements made in meteorological networks for 90 stations from 1994 to 1997. Bias is less than 1 W m-² for the whole set. Larger bias may be observed at individual sites, ranging from -15 to +32 W m-². For the whole set, the root mean square difference is 35 W m-² (17%) for daily mean irradiance and 25 W m-² (12%) for monthly mean irradiance. These accuracies are close to those of similar data sets of irradiance, such as Medias and NASA Surface Radiation Budget. It is concluded that B2 data can be used in a reliable way to produce long-term time-series of irradiance for Europe, Africa and the Atlantic Ocean