An analytic approximation to the Diffusion Coefficient for the periodic Lorentz Gas

An approximate stochastic model for the topological dynamics of the periodic triangular Lorentz gas is constructed. The model, together with an extremum principle, is used to find a closed form approximation to the diffusion coefficient as a function of the lattice spacing. This approximation is superior to the popular Machta and Zwanzig result and agrees well with a range of numerical estimates.Comment: 13 pages, 4 figure

Extensive admixture and selective pressure across the Sahel Belt

Genome-wide studies of African populations have the potential to reveal powerful insights into the evolution of our species, as these diverse populations have been exposed to intense selective pressures imposed by infectious diseases, diet, and environmental factors. Within Africa, the Sahel Belt extensively overlaps the geographical center of several endemic infections such as malaria, trypanosomiasis, meningitis, and hemorrhagic fevers. We screened 2.5 million single nucleotide polymorphisms in 161 individuals from 13 Sahelian populations, which together with published data cover Western, Central, and Eastern Sahel, and include both nomadic and sedentary groups. We confirmed the role of this Belt as a main corridor for human migrations across the continent. Strong admixture was observed in both Central and Eastern Sahelian populations, with North Africans and Near Eastern/Arabians, respectively, but it was inexistent in Western Sahelian populations. Genome-wide local ancestry inference in admixed Sahelian populations revealed several candidate regions that were significantly enriched for non-autochthonous haplotypes, and many showed to be under positive selection. The DARC gene region in Arabs and Nubians was enriched for African ancestry, whereas the RAB3GAP1/LCT/MCM6 region in Oromo, the TAS2R gene family in Fulani, and the ALMS1/NAT8 in Turkana and Samburu were enriched for non-African ancestry. Signals of positive selection varied in terms of geographic amplitude. Some genomic regions were selected across the Belt, the most striking example being the malaria-related DARC gene. Others were Western-specific (oxytocin, calcium, and heart pathways), Eastern-specific (lipid pathways), or even population-restricted (TAS2R genes in Fulani, which may reflect sexual selection).People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme FP7/2007-2013/ under REA grant agreement no. 290344 (EUROTAST). This project was also supported by the Grant Agency of the Czech Republic (13-37998S-P505). P.S. is supported by FCT (the Portuguese Foundation for Science and Technology), through FCT Investigator Programme (IF/01641/2013). IPATIMUP integrates the i3S Research Unit, which is partially supported by FCT. FEDER, COMPETE, and FCT fund IPATIMUP (PEst-C/SAU/LA0003/2013) and CBMA (PEst-OE/BIA/UI4050/2014

Food production and consumption in Bamyan Province, Afghanistan: the challenges of sustainability and seasonality for dietary diversity

In Asia, high levels of malnutrition threaten the health and livelihoods of millions of households. This paper concentrates on linkages between agriculture and nutrition in Afghanistan where food and nutrition insecurity are increasing and agricultural sustainability is increasingly compromised by climate change. We explore seasonal patterns of food production and consumption in the remote and robust ecological environment of Shah Foladi, Bamyan Province. Analysis of qualitative data from household interviews in eight villages has provided a wealth of insights into the seasonality of diets. Even within a broadly homogeneous environment, households were found to be markedly heterogeneous in respect of their assets, production, market, finance and employment strategies. The so-called ‘lean season’ was found to vary accordingly. Nevertheless, a general lack of dietary diversity during much of the year is likely to cause micronutrient malnutrition, especially for the vulnerable groups of children, adolescent girls and women. Potential interventions are proposed which need to account for the local context in order to overcome the natural and political constraints. These strategies include agricultural innovation and multi-sectoral policy approaches. In the end, reducing national insecurity is a pre-requisite for sustainable improvement in nutrition-sensitive agricultural development

The state of ambient air quality in Pakistan—a review

Background and purpose: Pakistan, during the last decade, has seen an extensive escalation in population growth, urbanization, and industrialization, together with a great increase in motorization and energy use. As a result, a substantial rise has taken place in the types and number of emission sources of various air pollutants. However, due to the lack of air quality management capabilities, the country is suffering from deterioration of air quality. Evidence from various governmental organizations and international bodies has indicated that air pollution is a significant risk to the environment, quality of life, and health of the population. The Government has taken positive steps toward air quality management in the form of the Pakistan Clean Air Program and has recently established a small number of continuous monitoring stations. However, ambient air quality standards have not yet been established. This paper reviews the data being available on the criteria air pollutants: particulate matter (PM), sulfur dioxide, ozone, carbon monoxide, nitrogen dioxide, and lead. Methods: Air pollution studies in Pakistan published in both scientific journals and by the Government have been reviewed and the reported concentrations of PM, SO2, O3, CO, NO2, and Pb collated. A comparison of the levels of these air pollutants with the World Health Organization air quality guidelines was carried out. Results: Particulate matter was the most serious air pollutant in the country. NO2 has emerged as the second high-risk pollutant. The reported levels of PM, SO2, CO, NO2, and Pb were many times higher than the World Health Organization air quality guidelines. Only O3 concentrations were below the guidelines. Conclusions: The current state of air quality calls for immediate action to tackle the poor air quality. The establishment of ambient air quality standards, an extension of the continuous monitoring sites, and the development of emission control strategies are essential. © Springer-Verlag 2009

Reflecting on ICN2: Was it a game changer?

At the Second International Conference on Nutrition (ICN2), November 2014, 170 member states endorsed the Rome Declaration on Nutrition and a Framework for Action. The Rome Declaration committed to ending malnutrition in all its forms while the Framework for Action offered 60 voluntary actions to help achieve this. These documents and ICN2 itself had the potential to be a major step forward for public health nutrition, addressing issues associated with today's complex food system. This article reviews ICN2, its process, outputs and some of the gaps and weaknesses of the documents. ICN2's legacy can be interpreted in two ways-a missed opportunity or one of broad aspirations which have yet to translate into meaningful action. The paper considers whether ICN2 could have adopted a more ecological approach to diet and nutrition, linking health and sustainability. While this fits the evidence, it would require a strong commitment to coherence and food system change, almost certainly a firm stance on some food corporate power, and resolve to champion health at the heart of economic policy. This ambitious agenda would require specific multi-actor and multi-level action, together with metrics and mechanisms for accountability. Coherent government policies and actions to tackle all manifestations of inappropriate diet, and to reframe the economic forces which shape such diets are urgently required. To achieve this, the public health movement needs to work closely with civil society, yet ICN2 showed that there is some reluctance to energise that combination. As a result, ICN2 must be judged a missed opportunity, despite having useful aspirations

Water quality and its interlinkages with the Sustainable Development Goals

Interlinkages among the Sustainable Development Goals (SDGs) lead to important trade-offs and synergies among the goals and their underlying targets. The aim of this paper is to review the role of water quality as an agent of interlinkages among the SDGs. It was found that there are a small number of explicit interconnections, but many more inferred interlinkages between water quality and various targets. A review of case studies showed that interlinkages operate from the municipal to near global scales, that their importance is likely to increase in developing countries, and that new SDG indicators are needed to monitor them. The analysis identifies many different SDG target areas where a combined effort between the water quality community and other sectors would bring mutual benefits in achieving the water quality and other targets

Reuse of materials from a Sustainable Drainage System device: Health, Safety and Environment assessment for an end-of-life Pervious Pavement Structure

Pervious pavement systems can have a life span of about 20 years but, at end-of-life, it becomes necessary to evaluate the state of the infrastructure to determine whether they pose a health and safety risk to workers during dismantling, and also determine potential reuse of the waste material generated. In this paper, we report of an investigation conducted to evaluate whether Pervious pavement systems are hazardous to human health at end-of-life and also to assess the mobility of the stormwater pollutants trapped in the system as a measure of their potential release to receiving systems such as water-bodies and groundwater systems. After decommissioning, the pervious pavement structure was sampled for analysis including Gas Chromatography, inductively coupled plasma spectroscopy and, leachate analysis. Results show that carcinogenic risks were significantly below the regulatory limit of 1 × 10–6 while, the hazard quotients and cumulative hazard indices were also below regulatory value of 1, based on United States Environmental Protection Agency standards. Furthermore, mean concentrations of benzene, toluene, ethylbenzene and xylene were significantly less than the UK soil guideline values. The results of the leachate analysis show that the metals of concern, Pb, Zn, Cr, Ni, Cd and Cu were all below the threshold for reuse applications such as irrigation purposes as they were all below the regulatory limits such as Food and Agriculture Organization and, United States Environmental Protection Agency standards. Finally, the evaluation of potential reuse and recycling purposes indicate that wastes generated from the dismantling of the PPS are within limits for recycling as aggregates for other civil engineering projects as per European Union standards. This has potential to enhance UK's drive to achieve the target of 70% level of construction & demolition waste recovery for reuse and recycling by the year 2020 as per European Union Water Framework Directive