Stochastic, Compartmental, and Dynamic Modeling of Cross-Contamination During Mechanical Smearing of Cheeses

Cheese smearing is a complex process and the potential for cross-contamination with pathogenic or undesirable microorganisms is critical. During ripening, cheeses are salted and washed with brine to develop flavor and remove molds that could develop on the surfaces. Considering the potential for cross-contamination of this process in quantitative risk assessments could contribute to a better understanding of this phenomenon and, eventually, improve its control. The purpose of this article is to model the cross-contamination of smear-ripened cheeses due to the smearing operation under industrial conditions. A compartmental, dynamic, and stochastic model is proposed for mechanical brush smearing. This model has been developed to describe the exchange of microorganisms between compartments. Based on the analytical solution of the model equations and on experimental data collected with an industrial smearing machine, we assessed the values of the transfer parameters of the model. Monte Carlo simulations, using the distributions of transfer parameters, provide the final number of contaminated products in a batch and their final level of contamination for a given scenario taking into account the initial number of contaminated cheeses of the batch and their contaminant load. Based on analytical results, the model provides indicators for smearing efficiency and propensity of the process for cross-contamination. Unlike traditional approaches in mechanistic models, our approach captures the variability and uncertainty inherent in the process and the experimental data. More generally, this model could represent a generic base to use in modeling similar processes prone to cross-contamination.     

Indigenous (im)mobilities in the Anthropocene

ABSTRACT

This paper explores Indigenous (im)mobilities in the Anthropocene, and their relationship to Pacific Islands climate activism. In a context where Indigenous peoples and perspectives are poorly represented in global climate politics, it is important to understand how Pacific people represent their own interests and imagine their own futures as pressures to move due to climate change take hold. We examine political action outside of formal governance spaces and processes, in order to understand how Indigenous people are challenging state-centric approaches to climate change adaptation. We do so by studying the works of Pacific activists and artists who engage with climate change. We find that *banua – an expansive concept, inclusive of people and their place, attentive to both mobility and immobility, and distributed across the Pacific Islands region – is essential for the existential security of Pacific people and central to contemporary climate activism. We find that Pacific activists/artists are challenging the status quo by invoking *banua. In doing so, they are politicising (im)mobility. These mobilisations are coalescing into an Oceanic cosmopolitanism that confronts two mutually reinforcing features of contemporary global climate politics: the subordination of Indigenous peoples, perspectives and worldviews; and the marginalisation of (im)mobility concerns within the global climate agenda.     

Lifetime risk of pregnancy-related death among Zambian women: district-level estimates from the 2010 census

The aim of this study was to examine district differentials in the lifetime risk of pregnancy-related death among females aged 15–49 in Zambia. We used data on household deaths collected in the 2010 census to estimate the lifetime risk of pregnancy-related death among females in Zambia. Using all-cause age-specific death rates, we generated female life tables for 74 districts and estimated person-years of exposure to all-cause mortality at each age. We then applied age-specific pregnancy-related mortality rates to the person-years of exposure to obtain estimates of adult lifetime risk that took account of competing causes of death. We used the ArcGIS software to analyse clustering and the spatial distribution of risk. A female aged 15 in Zambia had a 3.7 % chance of dying a pregnancy-related death before the age of 50. At district level, the lifetime risk ranged from 1.7 to 7.7 %. The Global Moran’s I was 0.452 (z-score 5.8, p value <0.01), indicating clustering of districts with similar risk levels of pregnancy-related mortality. Clustering of high-risk districts was found in Western province while clustering of low risk districts was found in Lusaka and Muchinga provinces. The level of adult lifetime risk was more positively associated with pregnancy-related mortality than with fertility. Females in Zambia have a high lifetime risk of pregnancy-related death overall but this risk varies greatly across the different districts of the country. The observed diversity is larger than when merely studying differences between provinces and is only weakly linked to differences in fertility levels. The identification of districts with varying levels of risk should enable evidence-based and focused delivery of maternal health services in districts where risk of death from maternal causes is greatest.     

Prediction of long memory processes on same-realisation

For the class of stationary Gaussian long memory processes, we study some properties of the least-squares predictor of _Xn+1$X_{n+1}$ based on (_Xn,…,_X1)$(X_n,\dots ,X_1)$. The predictor is obtained by projecting _Xn+1$X_{n+1}$ onto the finite past and the coefficients of the predictor are estimated on the same realisation. First we prove moment bounds for the inverse of the empirical covariance matrix. Then we deduce an asymptotic expression of the mean-squared error. In particular we give a relation between the number of terms used to estimate the coefficients and the number of past terms used for prediction, which ensures the L²$L^2$- sense convergence of the predictor. Finally we prove a central limit theorem when our predictor converges to the best linear predictor based on all the past.     

The process of evaluating a capacity-building support initiative for HIV positive South Africans

This paper describes the process of evaluating a capacity-building initiative involving HIV positive South Africans. The evaluation was conducted within a participatory evaluation framework, which aims at empowering participants through social action. The rationale is that an understanding and acceptance of evaluation results promotes commitment to act. Forty four members of the Kudu Support Group and 23 non-members participated in the evaluation. Methods included in-depth interviews, a survey, repeated measures of the General Health Questionnaire-28 (GHQ-28), a SWOT analysis, interviews with health workers, field notes, and participatory observation. The capacity-building initiative resulted in empowerment through paid employment for support group members, the establishment of a vegetable garden, increased skills and efficacy, access to resources and networks, a perceived reduction of stigma, perceived improvement of social relations, and improved scores on the GHQ-28. Lessons that emerge out of this study are the importance of integrating evaluation as a part of ongoing activities throughout the research project; to ensure that methods and results are understandable and useful to for the participants; that the evaluator has an in-depth understanding of the project and context; and to introduce frequent and simple internal evaluation tools to guide efforts to improve community-based groups’ functioning and activities.     

Quantitative Risk Assessment Relating to Adventitious Presence of Allergens in Food: A Probabilistic Model Applied to Peanut in Chocolate

Peanut allergy is a public health concern, owing to the high prevalence in France and the severity of the reactions. Despite peanut-containing product avoidance diets, a risk may exist due to the adventitious presence of peanut allergens in a wide range of food products. Peanut is not mentioned in their ingredients list, but precautionary labeling is often present. A method of quantifying the risk of allergic reactions following the consumption of such products is developed, taking the example of peanut in chocolate tablets. The occurrence of adventitious peanut proteins in chocolate and the dose-response relationship are estimated with a Bayesian approach using available published data. The consumption pattern is described by the French individual consumption survey INCA2. Risk simulations are performed using second-order Monte Carlo simulations, which separately propagates variability and uncertainty of the model input variables. Peanut allergens occur in approximately 36% of the chocolates, leading to a mean exposure level of 0.2 mg of peanut proteins per eating occasion. The estimated risk of reaction averages 0.57% per eating occasion for peanut-allergic adults. The 95% values of the risk stand between 0 and 3.61%, which illustrates the risk variability. The uncertainty, represented by the 95% credible intervals, is concentrated around these risk estimates. Children have similar results. The conclusion is that adventitious peanut allergens induce a risk of reaction for a part of the French peanut-allergic population. The method developed can be generalized to assess the risk due to the consumption of every foodstuff potentially contaminated by allergens.     

Quantitative Risk Assessment of Haemolytic and Uremic Syndrome Linked to O157:H7 and Non‐O157:H7 Shiga‐Toxin Producing Escherichia coli Strains in Raw Milk Soft Cheeses

Shiga‐toxin producing Escherichia coli (STEC) strains may cause human infections ranging from simple diarrhea to Haemolytic Uremic Syndrome (HUS). The five main pathogenic serotypes of STEC (MPS‐STEC) identified thus far in Europe are O157:H7, O26:H11, O103:H2, O111:H8, and O145:H28. Because STEC strains can survive or grow during cheese making, particularly in soft cheeses, a stochastic quantitative microbial risk assessment model was developed to assess the risk of HUS associated with the five MPS‐STEC in raw milk soft cheeses. A baseline scenario represents a theoretical worst‐case scenario where no intervention was considered throughout the farm‐to‐fork continuum. The risk level assessed with this baseline scenario is the risk‐based level. The impact of seven preharvest scenarios (vaccines, probiotic, milk farm sorting) on the risk‐based level was expressed in terms of risk reduction. Impact of the preharvest intervention ranges from 76% to 98% of risk reduction with highest values predicted with scenarios combining a decrease of the number of cow shedding STEC and of the STEC concentration in feces. The impact of postharvest interventions on the risk‐based level was also tested by applying five microbiological criteria (MC) at the end of ripening. The five MCs differ in terms of sample size, the number of samples that may yield a value larger than the microbiological limit, and the analysis methods. The risk reduction predicted varies from 25% to 96% by applying MCs without preharvest interventions and from 1% to 96% with combination of pre‐ and postharvest interventions.     

Differences in Internalizing Symptoms Anticipate Adolescent Friendship Dissolution

This study examined the degree to which internalizing symptoms predict adolescent friendship instability. A total of 397 adolescents identified 499 same‐sex reciprocated friendships that originated in the seventh grade (M = 13.18 years). Discrete‐time survival analyses were conducted with Grade 7 peer, teacher, and self‐reports of internalizing symptoms as predictors of friendship dissolution across Grades 8–12. Differences between friends in depressive symptoms, anxiety symptoms, and (for boys only) submissiveness predicted subsequent friendship dissolution. Individual levels of these variables did not predict friendship dissolution, even at extreme or clinical levels. The findings suggest that friendship instability arising from internalizing problems stems from dissimilarity between friends rather than the presence of psychopathological symptoms on the part of one friend.