Nanopore Fabrication by Controlled Dielectric Breakdown

Nanofabrication techniques for achieving dimensional control at the nanometer scale are generally equipment-intensive and time-consuming. The use of energetic beams of electrons or ions has placed the fabrication of nanopores in thin solid-state membranes within reach of some academic laboratories, yet these tools are not accessible to many researchers and are poorly suited for mass-production. Here we describe a fast and simple approach for fabricating a single nanopore down to 2-nm in size with sub-nm precision, directly in solution, by controlling dielectric breakdown at the nanoscale. The method relies on applying a voltage across an insulating membrane to generate a high electric field, while monitoring the induced leakage current. We show that nanopores fabricated by this method produce clear electrical signals from translocating DNA molecules. Considering the tremendous reduction in complexity and cost, we envision this fabrication strategy would not only benefit researchers from the physical and life sciences interested in gaining reliable access to solid-state nanopores, but may provide a path towards manufacturing of nanopore-based biotechnologies.Comment: 19 pages, 4 figures. Supplementary information contains 22 pages, 11 figures and 2 tables - A version of this manuscript was first submitted for publication on April 23rd, 2013. It is currently under review at another journa

Learning-By-Doing Vs. On-the-Job Training: Using Variation Induced by the EITC to Distinguish Between Models of Skill Formation

This paper investigates the impact of wage subsidies on skill formulation. We analyze two prototypical models of skill formation: (a) a learning-by-doing model and (b) an on-the-job training model. We develop conditions on the pricing of jobs under which the two models are equivalent. In general they are different and have different implications of wage subsidies on skill formation. On-the-job training models predict that wage subsidies reduce skill formation. Learning-by-doing models predict the opposite. The provisional evidence favors the learning-by-doing model. We apply our estimates to investigate the impact of the EITC on skill formation. We estimate that the EITC reduced the long term wages of participants with low levels of education.

African Renaissance and Globalization: A Conceptual Analysis and a Way Forward

After colonialism and subsequent independences of African states, the current wave of Globalization has been compelling Africans to rethink their position in the world. One key aspect of Africa’s redefinition and response to Globalization is the African Renaissance; a concept that has been subject to debate among African academia, with some African scholars arguing that it is borrowed from experiences unique to Europe and thus rendering it irrelevant to Africa. This paper is a conceptual analysis of the term African Renaissance and an assessment of its relevance within the context of globalization

Lost Girls, Dead Poets, Last Waves

The Australian film director Peter Weir has created, over the last twenty years, a body of work of remarkable quality and consistency of vision. In virtually all of his films something -- often quite literally someone -- gets lost. Innocence, idealism, and faith are the usual casualties. Moreover, there is nearly always a clash of cultures. His characters are thrown into a milieu they are not equipped to understand, one that seems hostile and threatening if only for its strangeness. In this, Weir is the quintessential Aussie; the perennial outsider. Australians are neither European, nor Asian, nor South Sea Islanders, yet they are all of these. Picnic at Hanging Rock (1975) takes place on St. Valentine's Day, 1900, at a girls' school in Southeast Australia, a Victorian outpost on the edge of the bush. In the atmosphere of hothouse romanticism that pervades the place the girls exchange valentines and love..

Savings of young parents

In this paper, we examine household savings using data from the National Longitudinal Survey, Cohort 1997 (NLSY97). This data set provides detailed information about assets and liabilities of parents with teen-age children and allows researchers to examine patterns of accumulation at early stages of the life cycle. In our empirical work, we have first to deal with several problems in measuring wealth. While many respondents report owning assets and liabilities, they often do not report their values. This problem is severe, in particular among financial assets. It is also difficult to devise an appropriate measure of accumulation when examining young parents, since assets and liabilities display different degrees of liquidity. To get around the non-response problem, we impute the missing values for assets and liabilities. This allows us to calculate household wealth for the whole sample. We examine household wealth holdings by considering several measures of accumulation: total (non-pension) net worth, financial net worth, and retirement savings. We study their distribution across different demographic groups and show that many households, in particular those headed by young parents (younger than 35), minorities, and individuals with low educational attainment, display very little accumulation. Many have no financial assets and their total net worth is also low. Housing equity is the main asset in many household portfolios and often the only asset families own. Overall, there is much heterogeneity in wealth holdings not only across but also within demographic groups. This suggests that many factors are at play in shaping the wealth accumulation of parents with young children.Wealth ; Saving and investment

African Renaissance and Globalization: A Conceptual Analysis and a Way Forward

After colonialism and subsequent independences of African states, the current wave of Globalization has been compelling Africans to rethink their position in the world. One key aspect of Africa’s redefinition and response to Globalization is the African Renaissance; a concept that has been subject to debate among African academia, with some African scholars arguing that it is borrowed from experiences unique to Europe and thus rendering it irrelevant to Africa. This paper is a conceptual analysis of the term African Renaissance and an assessment of its relevance within the context of globalization

System Transfer, Education, and Development in Mozambique

In this study the author used conceptual historical method to assess the phenomenon of system transfer and the association between education and development in Mozambique. The assessment was administered through critical analysis of documents pertaining to the Salazar (1924-1966), Machel (1975-1986), and Chissano (1986-2005) administrations. The findings were that (a) the colonial government created economic and educational systems for colonizing Mozambique, whereas the Machel and Chissano administrations adapted foreign systems of government and education (i.e., Socialism, Soviet, Democracy, Portuguese, etc.), to their particular context without altering the inherent theoretical basis of the systems transferred; (b) the Machel and Chissano administrations, implicitly or explicitly, perceived the relationship between education and development as circular causality rather than a unidirectional linear causality, while the Salazar administration perceived it as unidirectional linear causality; and (c) while the Machel and Chissano administrations focused on primary education, literacy campaigns, and education of women and girls, they differed in the reasons for such focus

Authority, trust and accountability : regulation of pharmaceutical drug trade practices in Yeoville.

The increase in use and distribution of pharmaceuticals on a global scale has caused pharmaceuticals to play an integral role in the notions of quality of health. This study is concerned with how Western medication is transacted and interpreted in explicit and implicit contrast to the other context. I observe the commercial trade of medicines, specifically the effects of regulation of pharmaceutical drug trade in a suburb of Johannesburg (Yeoville) a low income area where many migrant groups have found long and short term refuge. A Policing and Mobility Project (Hornberger & Cossa 2010) centred on tracing paths of medication and the level of policing thereof in Johannesburg revealed that clandestine sale of medication occurs in the suburb’s local market. This prompted a comparison between the formal and informal pharmaceutical trade spaces. Simon (a pharmacist) and Teresa (a former nurse turned market trader) sell pharmaceutical drugs in seemingly contrasting contexts. Despite their expertise in health care, Simon and Teresa were flung to opposite ends of the trade spectrum by regulation. In the weeks I spent with Teresa and Simon it became abundantly clear that the spaces which had been initially presented as the opposite of one another may have had a few layers of common ground. At first it seems as though only regulation has the ability to produce authority, trust and accountability. But later it becomes evident that such aspects can be reproduced through manipulation of everyday practices. Roger Cotterrell’s (1999) interpretation of Emile Durkheim’s view of the law as a ‘Social Fact’ (1999:9), demonstrates how the collective experience of regulation (an aspect of the law) affects the individual. But De Certeau (1984) claims that the same individual can tacitly undermine this collective experience (the dominant form) through everyday practices. The findings suggest that the assumed roles of regulated and unregulated pharmaceutical trading spaces are not as static as they appear. The study concluded that authority, trust and accountability can be reproduced outside of regulation. And secondly thus the formal and informal trade of pharmaceuticals in Yeoville have more in common than perceived since both Simon and Teresa, had authority in health, their customer’s trust and loyalty and were accountable within the trade

Gli elementi di frontiera per i calcoli di neutronica in tre dimensioni

Dopo una breve esposizione delle caratteristiche e delle prospettive del metodo agli elementi di frontiera, si illustra una nuova tecnicsa di calcolo per gli integrali di influenza e per la determinazione del flusso neutronico in sistemi 3D