Targeting vaccination against novel infections: risk,age and spatial structure for pandemic influenza in Great Britain

The emergence of a novel strain of H1N1 influenza virus in Mexico in 2009, and its subsequent worldwide spread, has focused attention to the question of optimal deployment of mass vaccination campaigns. Here, we use three relatively simple models to address three issues of primary concern in the targeting of any vaccine. The advantages of such simple models are that the underlying assumptions and effects of individual parameters are relatively clear, and the impact of uncertainty in the parametrization can be readily assessed in the early stages of an outbreak. In particular, we examine whether targeting risk-groups, age-groups or spatial regions could be optimal in terms of reducing the predicted number of cases or severe effects; and how these targeted strategies vary as the epidemic progresses. We examine the conditions under which it is optimal to initially target vaccination towards those individuals within the population who are most at risk of severe effects of infection. Using age-structured mixing matrices, we show that targeting vaccination towards the more epidemiologically important age groups (5–14 year olds and then 15–24 year olds) leads to the greatest reduction in the epidemic growth and hence reduces the total number of cases. Finally, we consider how spatially targeting the vaccine towards regions of country worst affected could provide an advantage. We discuss how all three of these priorities change as both the speed at which vaccination can be deployed and the start of the vaccination programme is varied.     

Characterisation of amine functionalised poly(3-hydroxybuturate-co-3-hydroxyvalerate) surfaces

There is an increasing acceptance of the importance of tailoring biomaterial surface properties. This study aimed to introduce and characterise amine functionalities onto the hydrophobic bacterial polymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). Gamma irradiation induced simultaneous grafting of 2-aminoethyl methacrylate (AEMA) onto PHBV films was carried out using various concentrations of AEMA (2.5 or 4.5 w/v%) in either water or methanol and at two irradiation doses (4.5 or 9 kGy). Successful grafting was verified from XPS analysis, water contact angle and ATR-FTIR spectroscopy. Characterisation using DSC indicated that grafting had occurred predominantly in the amorphous region of the PHBV substrate. ¹H NMR of the grafting solution post grafting showed that monomer conversion is incomplete in methanol. The use of gold nano-particles (AuNPs) as a simple tool to probe the presence of these functional groups was evaluated using a suspension of citrate functionalized AuNPs prepared by reduction of Au(III) with citric acid. These particles were found to be polydisperse (0.8-2 nm and 7-70 nm) and negatively charged (zeta potential of −33 ± 9 mV) and capable of interacting electrostatically with the amine groups on the PHBV surface and imaged using SEM.     

Advancing post-anoxic denitrification for biological nutrient removal

The objective of this research was to advance a fundamental understanding of a unique post-anoxic denitrification process for achieving biological nutrient removal (BNR), with an emphasis on elucidating the impacts of surface oxygen transfer (SOT), variable process loadings, and bioreactor operational conditions on nitrogen and phosphorus removal. Two sequencing batch reactors (SBRs) were operated in an anaerobic/aerobic/anoxic mode for over 250 days and fed real municipal wastewater. One SBR was operated with a headspace open to the atmosphere, while the other had a covered liquid surface to prevent surface oxygen transfer. Process performance was assessed for mixed volatile fatty acid (VFA) and acetate-dominated substrate, as well as daily/seasonal variance in influent phosphorus and ammonia loadings. Results demonstrated that post-anoxic BNR can achieve near-complete (>99%) inorganic nitrogen and phosphorus removal, with soluble effluent concentrations less than 1.0 mgN L⁻¹ and 0.14 mgP L⁻¹. Observed specific denitrification rates were in excess of typical endogenous values and exhibited a linear dependence on the glycogen concentration in the biomass. Preventing SOT improved nitrogen removal but had little impact on phosphorus removal under normal loading conditions. However, during periods of low influent ammonia, the covered reactor maintained phosphorus removal performance and showed a greater relative abundance of polyphosphate accumulating organisms (PAOs) as evidenced by quantitative real-time PCR (qPCR). While GAOs were detected in both reactors under all operational conditions, BNR performance was not adversely impacted. Finally, secondary phosphorus release during the post-anoxic period was minimal and only occurred if nitrate/nitrite were depleted post-anoxically.     

Effect of prenatal exposure to fine particulate matter and intake of Paracetamol (Acetaminophen) in pregnancy on eczema occurrence in early childhood

The goal of the study was to test the hypothesis that prenatal Paracetamol exposure increases the risk of developing eczema in early childhood and that this association may be stronger in children who are exposed in fetal period to higher concentrations of fine particulate matter (PM_2.5). The study sample consisted of 322 women recruited from January 2001 to February 2004 in the Krakow inner city area who gave birth to term babies and completed 5-year follow-up. Paracetamol use in pregnancy was collected by interviews and prenatal personal exposure to PM_2.5 over 48 h was measured in recruited women in the second trimester of pregnancy. After delivery, every three months in the first 24 months of the newborn's life and every 6 months later, a detailed standardized face-to-face interview on the infant's health was administered to each mother by trained interviewers. During the interviews at each of the study periods after birth, a history of eczema was recorded.The incident rate ratio (IRR) for frequency of eczema events over the follow-up was estimated from the Poisson regression model and the overall effect of main exposure variables on eczema was assessed by odds ratios (ORs) by the logistic model. The estimated relative risk of eczema occurring whenever in the follow-up was related significantly neither with prenatal Paracetamol nor higher PM_2.5 exposure, however, their joint effect was significant (OR interaction term = 6.04; 95%CI: 1.04-35.16). Of potential confounders considered in the analysis only damp/moldy home significantly increased the risk of eczema (OR = 1.53; 95%CI: 1.14-2.05). In contrast, there was an inverse significant association between the presence of older siblings and eczema (OR = 0.55; 95%CI: 0.35-0.84). The joint effect of the main exposure variables significantly increased frequency of eczema events (IRR = 1.78, 95%CI: 1.22-2.61).In conclusion, the findings of the study suggest that Paracetamol use by mothers in pregnancy is not an independent risk factor for eczema in children, however, even very small doses of Paracetamol taken in pregnancy may contribute to the occurrence of allergic symptoms in early childhood if there is prenatal co-exposure to higher airborne fine particulate matter.     

Development and implementation of hazard analysis and critical control point plans by several U.S. feed manufacturers

The commitment to consumer food safety, global trade, and proposed new regulations by the U.S. Food and Drug Administration Center for Veterinary Medicine has led to increased adoption of hazard analysis and critical control point (HACCP) by the U.S. feed industry. A project supported by the U.S. Department of Agriculture Integrated Food Safety Initiate titled "Development and Implementation of a Voluntary HACCP Program for the US Feed Industry" enabled faculty from three land grant universities to assist individuals from 14 feed companies that collectively manufacture 15 million metric tons of feed in 100 facilities to develop HACCP plans. The process flow in these plans averaged 20 steps, and the most detailed plan included 60 process steps. Chemical hazards were more commonly identified in HACCP plans (average of four hazards per plan) than were biological hazards (average of one per plan). The most prevalent chemical hazards were cross-contamination of type A medicated articles and type B medicated feeds, aflatoxin, and wrong ingredient inclusion in feed. The most common biological hazard was mammalian protein contamination of feed ingredients and finished feed for cattle. An assessment of time and costs associated with developing HACCP plans revealed that approximately 29% of the companies needed additional personnel or additional equipment to implement a HACCP plan, and on average 268 additional person hours were needed to develop and implement a HACCP plan. Plan design, compliance monitoring, and record keeping were the three most time-consuming activities needed for developing and implementing a HACCP plan. The average cost of additional equipment needed to implement a HACCP plan was $250.     

Nutrient content of milk and milk products: water soluble vitamins in baby milk formulae

A study of the content of water soluble vitamins in the 12 baby milk formulae available in the UK in April 1983 showed that levels of vitamins in the individual brands were generally in excess of those declared by the manufacturer. For cows' milk based formulae the mean excess of vitamins over the declared level was 94%. Vitamin levels in prepared formulae averaged three times the minimum recommended level. The average level of B vitamins in prepared cows' milk based formulae was six times higher than in mature human milk. For the two soya based products, the levels of vitamins were generally in excess of the declared level and levels of vitamin B12, biotin and, in one sample, vitamin B6 were considerably in excess of those found in mature human milk.     

Shelf-Life of Pasteurized Fluid Milk as Affected by Age of Raw Milk

Increasing raw milk storage time prior to pasteurization may affect product shelf-life. Raw milk was stored at 4.5°C for 0, 2, 4, and 6 days prior to pasteurizing. Milk samples from each pasteurized lot were analyzed after continuous storage at 4.5°C for 0, 4, 8, 12, 16, and 20 days. Both raw and pasteurized samples were analyzed for coliforms, psychrotrophs, and total bacteria counts. Flavor scores were also determined. No correlations were significant between raw or pasteurized samples and total bacteria or coliform counts. Related were flavor score and days held raw, shelf-life of the resulting pasteurized product, and interaction of days held raw and shelf-life of the pasteurized product. Psychrotrophic counts and age of the raw milk were correlated. From correlations of flavor scores with shelf-life of the milk, a predictive equation was: Flavor score = 8.00 – .88 R – .11 P – .0015 P² – .009 R P, where R is days held raw and P is shelf-life of the pasteurized product.     

Impaired fertility in T-stock female mice after superovulation

Superovulation of female mice with exogenous gonadotrophins is routinely used for increasing the number of eggs ovulated by each female in reproductive and developmental studies. We report an unusual effect of superovulation on fertilization in mice. In vivo matings of superovulated T-stock females with B6C3F1 males resulted in a two-fold reduction (P <0.001) in the frequencies of fertilized eggs compared with control B6C3F1 matings. In addition, approximately 22 h after mating, only 15% of fertilized eggs recovered in T-stock females had reached the metaphase stage of the first cleavage division versus 87% in B6C3F1 females (P <0.0001). Matings with T-stock males did not improve the reproductive performance of T-stock females. To investigate the possible cause(s) for the impaired fertilization and zygotic development, the experiments were repeated using in vitro fertilization. Under these conditions, the frequencies of fertilized eggs were not different in superovulated T-stock and B6C3F1 females (51.7 +/- 6.0 and 64.5 +/- 3.8%, P=0.10). There was a seven-fold increase in the frequencies of fertilized eggs that completed the first cell cycle of development after in vitro versus in vivo fertilization in T-stock females. These results rule out an intrinsic deficiency of the T-stock oocyte as the main reason for the impaired fertility after in vivo matings, and suggest that superovulation of T-stock females may induce a hostile oviductal and uterine environment with dramatic effects on fertilization and zygotic development.     

Simulation comparison of wake mitigation control strategies for a two‐turbine case

Wind turbines arranged in a wind plant impact each other through their wakes. Wind plant control is an active research field that attempts to improve wind plant performance by coordinating control of individual turbines to take into account these turbine–wake interactions. In this paper, high‐fidelity simulations of a two‐turbine fully waked scenario are used to investigate several wake mitigation strategies, including modification of yaw and tilt angles of an upstream turbine to induce wake skew, as well as repositioning of the downstream turbine. The simulation results are compared through change relative to a baseline operation in terms of overall power capture and loading on the upstream and downstream turbine. Results demonstrated improved power production for all methods. Analysis of control options, including individual pitch control, shows potential to minimize the increase of, or even reduce, turbine loads.Copyright © 2014 John Wiley & Sons, Ltd.     

Potential performance bottleneck in Linux TCP

Transmission control protocol (TCP) is the most widely used transport protocol on the Internet today. Over the years, especially recently, due to requirements of high bandwidth transmission, various approaches have been proposed to improve TCP performance. The Linux 2.6 kernel is now preemptible. It can be interrupted mid‐task, making the system more responsive and interactive. However, we have noticed that Linux kernel preemption can interact badly with the performance of the networking subsystem. In this paper, we investigate the performance bottleneck in Linux TCP. We systematically describe the trip of a TCP packet from its ingress into a Linux network end system to its final delivery to the application; we study the performance bottleneck in Linux TCP through mathematical modelling and practical experiments; finally, we propose and test one possible solution to resolve this performance bottleneck in Linux TCP. Copyright © 2007 John Wiley & Sons, Ltd.