Agricultural sustainability: concepts, principles and evidence

Concerns about sustainability in agricultural systems centre on the need to develop technologies and practices that do not have adverse effects on environmental goods and services, are accessible to and effective for farmers, and lead to improvements in food productivity. Despite great progress in agricultural productivity in the past half-century, with crop and livestock productivity strongly driven by increased use of fertilizers, irrigation water, agricultural machinery, pesticides and land, it would be over-optimistic to assume that these relationships will remain linear in the future. New approaches are needed that will integrate biological and ecological processes into food production, minimize the use of those non-renewable inputs that cause harm to the environment or to the health of farmers and consumers, make productive use of the knowledge and skills of farmers, so substituting human capital for costly external inputs, and make productive use of people's collective capacities to work together to solve common agricultural and natural resource problems, such as for pest, watershed, irrigation, forest and credit management. These principles help to build important capital assets for agricultural systems: natural; social; human; physical; and financial capital. Improving natural capital is a central aim, and dividends can come from making the best use of the genotypes of crops and animals and the ecological conditions under which they are grown or raised. Agricultural sustainability suggests a focus on both genotype improvements through the full range of modern biological approaches and improved understanding of the benefits of ecological and agronomic management, manipulation and redesign. The ecological management of agroecosystems that addresses energy flows, nutrient cycling, population-regulating mechanisms and system resilience can lead to the redesign of agriculture at a landscape scale. Sustainable agriculture outcomes can be positive for food productivity, reduced pesticide use and carbon balances. Significant challenges, however, remain to develop national and international policies to support the wider emergence of more sustainable forms of agricultural production across both industrialized and developing countries.     

Reproductive success by large, closely related males facilitated by sperm storage in an aggregate breeding amphibian

The outcome of sexual selection on males may depend on female mate choice and male–male competition as well as postcopulatory processes such as cryptic female choice and sperm competition. We studied the outcome of sexual selection in the spotted salamander ( Ambystoma maculatum ), specifically examining the role of body size and relatedness on male reproductive success. Using controlled mating experiments in the field, we gave females access to three males of different sizes. We used seven microsatellite loci to determine paternity in the resulting larvae, estimate relatedness ( r ) between females and their mates, and calculate md ² (a measure of within-individual genomic divergence), heterozygosity, and standardized heterozygosity in the larvae. Both body size and relatedness to the female were significant predictors of male reproductive success. The relatedness of the males available to a female did not influence the amount of stored sperm she used to sire her larvae. Nonetheless, computer simulations showed that the average md ², heterozygosity, and standardized heterozygosity of the offspring were lower than expected by random mating. These differences are due to the use of stored sperm to fertilize some eggs; md ², heterozygosity, and standardized heterozygosity of larvae sired by stored sperm were significantly lower than those of larvae sired by the experimental males. These results suggest that relatedness may further influence a male's long-term reproductive success by determining whether his sperm is stored for later breeding seasons. Sexual selection in this salamander likely involves a complex interaction among many factors and may act over many seasons.     

Capitalizing on nature: how to implement an ecosystem approach

The Natural Capital Initiative (www.naturalcapitalinitiative.org.uk) held its first conference ‘Valuing our life support systems’ at Savoy Place, London, from 29 April to 1 May 2009. The aim of the conference was to discuss different perspectives on, and solutions to, the conservation and sustainable use of ecosystem services. It particularly focused on the link between the environment and the economy, and how to implement an ecosystem approach to environmental management. This event brought together scientists across the natural and social sciences, alongside representatives from government, non-governmental organizations, business and industry.     

Sustainable livelihood framework-based indicators for assessing climate change vulnerability and adaptation for Himalayan communities

This study evaluated the climate change vulnerability of Himalayan communities, and their potential to adapt to these changes, through assessing their perceived reactions and counter-actions to climate change. The evaluation was conducted through proposing and testing indices for vulnerability (Climate Vulnerability Index – CVI) and adaptation (Current Adaptive Capacity Index – CACI) based on the assumption that a community is an active dynamic entity and has tremendous capability to address the impacts of climate change through an ability to make adjustments based on perceived experiences. Both CVI and CACI include the five forms of capital leading to sustainable livelihood, i.e. human, natural, financial, social and physical capital, and were assessed for each of these forms of capital based on the IPCC framework of vulnerability assessment and its three dimensions (exposure, sensitivity, adaptive capacity). Data for the analysis were collected from randomly selected households located away from district headquarters (ADH) and near district headquarters (NDH). Each dimension was measured based on associated socio-environment-specific indicators for assessing vulnerability and sustainability at community level. The results showed that ADH households had higher human capital and natural capital vulnerability than NDH households. In contrast, NDH households had higher social capital and financial capital vulnerability than ADH households. Overall, ADH households had greater vulnerability than NDH households.These results improve understanding of the environmental and socio-economic changes affecting rural livelihoods and the measures needed to address their specific vulnerabilities by addressing bottlenecks in education and training facilities for skill up-grading, increasing interaction opportunities through local functions and creating opportunities for income generation and effective market and farm linkages. An attempt was made to reduce the gap between bottom-up understanding and top-down policies by suggesting precautionary and ongoing adaptation practices for the communities studied, leading to effective and efficient addressal of vulnerabilities. Vulnerability in the study context was taken to mean externally driven change leading to disturbance in the human environment that could alter internal and external livelihood settings.     

The shape of things to come? household dependency ratio and adolescent nutritional status in rural and urban Ethiopia

Several related demographic trends are occurring in developing countries: youth comprise a large portion of populations, fertility rates are declining, and urban dwellers are increasing. As fertility rates decline and populations age, the decline in the ratio of young dependents to working age adults is expected to free up household resources, which can be invested in human capital, including youth nutritional wellbeing. We test this hypothesis in a sample of youth (n = 1,934) in Southwestern Ethiopia. Multiple measures of achieved growth and nutritional status are explored (weight, height, mid-upper arm circumference (MUAC), body mass index (BMI) and body mass index for age z-score (BMIZ), weight for age z-score (WAZ), and height for age z-score (HAZ)). In multivariable models controlling for the effects of income, age, gender, and youth workloads, youth living in rural settings had significantly lower weight (1.24 kg lighter), MUAC (0.67 cm lower), BMI (0.45 BMI lower), BMIZ (0.27 lower), HAZ (0.14 HAZ lower), and WAZ (0.3 WAZ lower) than urban youth (all P < 0.01). Compared with youth in the lowest dependency ratio households, results show that youth in households with the highest dependency ratios were estimated to be 1.3 kg lighter, have 0.67 cm smaller MUAC, and BMI that was 0.59 lower (all P<0.01). Similar results were found for WAZ (0.21 lower) and BMIZ (0.36 lower). Youth height and HAZ were not associated with household dependency. These results may point toward increasing levels of human capital investments in Ethiopian youth as fertility levels decline and populations urbanize.     

The blood-testis barrier: the junctional permeability, the proteins and the lipids

The elucidation of how individual components of the Sertoli cell junctional complexes form and are dismantled to allow not only individual cells but whole syncytia of germinal cells to migrate from the basal to the lumenal compartment of the seminiferous epithelium without causing a permeability leak in the blood-testis barrier is amongst the most enigmatic yet, challenging and timely questions in testicular physiology. The intriguing key event in this process is how the barrier modulates its permeability during the periods of formation and dismantling of individual Sertoli cell junctions. The purpose of this review is therefore to first provide a reliable account on the normal formation, maintenance and dismantling process of the Sertoli cells junctions, then to assess the influence of the expression of their individual proteins, of the cytoskeleton associated with the junctions, and of the lipid content in the seminiferous tubules on the regulation of the their permeability barrier function. To help focus on the formation and dismantling of the Sertoli cell junctions, several considerations are based on data gleaned not only from rodents but from seasonal breeders as well because these animal models are characterized by exhaustive periods of junction assembly during development and the onset of the seasonal re-initiation of spermatogenesis as well as by an extensive junction dismantling period at the beginning of testicular regression, something unavailable in normal physiological conditions in continual breeders. Thus, the modulation of the permeability barrier function of the Sertoli cell junctions is analyzed in the physiological context of the blood-epidydimis barrier and in particular of the blood-testis barrier rather than in the context of a detailed account of the molecular composition and signalisation pathways of cell junctions. Moreover, the considerations discussed in this review are based on measurements performed on seminiferous tubule-enriched fractions gleaned at regular time intervals during development and the annual reproductive cycle.     

Globalizing forms of elite sociability: varieties of cosmopolitanism in Paris social clubs

This article examines the cultivation of transnational connections, cosmopolitanism and global class consciousness among members of elite social clubs in Paris. Drawing from interviews with members, it compares how – according to their respective characteristics – various social clubs promote different kinds of bourgeois cosmopolitanism, while rejecting the more recent internationalism of upper-middle-class service clubs such as the Rotary. Each club's peculiar ethos, practice and representations of social capital are related to the features of competing clubs through relations of mutual symbolic distinction; for example, some clubs emphasize the ‘genuineness’ of links while stigmatizing others for the accent they put on utility. The varied forms of cosmopolitanism that they promote partly replicate these logics of distinction, eliciting struggles over the authenticity or inauthenticity of transnational connections. Yet, clubs also oppose each other according to the unequal emphasis that they place on international ties per se, which creates a competing axiology within the symbolic economy of social capital accumulation.     

Has multiculturalism failed in Britain?

Abstract

This paper subjects the criticisms advanced against multiculturalism to empirical test. It asks whether ethno-religious groups lead ‘parallel lives’ and, in consequence, fail to integrate with the wider society. It looks in particular at the alleged corrosive effects of multiculturalism, specifically at the maintenance of an ethnic rather than a British identity, social distance from white people and willingness to contemplate violent protest, but finds that all groups alike have displayed major change across the generations in the direction of a British identity and reduced social distance. It finds no evidence that rates of intergenerational change have been slower among ethno-religious groups that have made successful claims for cultural recognition. In contrast, lower levels of integration are associated with perceptions of individual or group discrimination.     

Construction of an Affordable and Easy-to-Build Zebrafish Facility

In vivo biomedical research is pivotal to translate in vitro findings into clinical advances. Small academic institutions with limited resources find it virtually impossible to build and maintain typical rodent facilities for research. Zebrafish research has been demonstrated to be a valuable alternative for in vivo research in pharmacology, physiology, development and genetic studies. This article demonstrates that a functional zebrafish facility can be built in an easy and affordable manner. We demonstrate that such a facility could be built in about one working day with minimal tools and expertise. The cost of the 27 1.8 L fish tank zebrafish facility constructed in this study was approximately $1,500. We estimate that the maintenance of an initial working 150 fish colony for 3 months is $1,000. This project involved students, who were introduced to aquaculturing of zebrafish for research proposes.