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.

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

An Econometric Cost-Benefit Analysis of Argentina's Youth Training Program

The Youth Training Program (YTP) was an important component of Argentina’s active labor policy of the 1990s. The program offered courses of three months’ duration, divided equally between lectures and practical experience, and targeted young people, most of whom were not employed and had a low level of education. The program was offered by different institutions chosen through a bidding process and included courses in the fields of agriculture, manufacture, construction and services. This paper conducts an econometric cost-benefit analysis of the fifth round of the YTP. Benefits (wage increases, increase in likelihood of employment, increase in earnings) are estimated using non-matching (Before and After, Cross Section and Difference in Difference) and matching techniques based on propensity score estimate (Nearest Neighbor, Kernel, Local Linear Regression) in order to avoid selection bias. Estimates of the ATE and TT effects are also provided. A sample consisting of 1,670 beneficiaries and a similarly-sized comparison group provided the information necessary to apply the methodology. Benefit estimates are made for the aggregate, by gender and for both youth and adults. Regional differences are also provided. The cost includes direct and indirect components and the alternative cost of beneficiaries reducing their contributions to output during the program. Estimates of rate of return are provided based on the previous benefit and cost estimation. In general, the results support an estimate of 10 percent of return. This looks reasonable if it is compared with the very low rate of return of education estimated separately for the beneficiaries group. Finally, the management of the program is evaluated.

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

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

Descreening of Field Effect in Electrically Gated Nanopores

This modeling work investigates the electrical modulation characteristics of field-effect gated nanopores. Highly nonlinear current modulations are observed in nanopores with non-overlapping electric double layers, including those with pore diameters 100 times the Debye screening length. We attribute this extended field-effect gating to a descreening effect, i.e. the counter-ions do not fully relax to screen the gating potential due to the presence of strong ionic transport

U.S.-China Strategic Nuclear Dialogue

Performer: Pacific Forum Center for Strategic and International Studies (CSIS) Project Lead: Ralph Cossa Project Cost: $212,009 FY16–17This research is anticipated to lead to greater understanding of strategic nuclear issues between the United States and China. The project will build a stronger relationship among scholars and experts in the United States and China. The dialogue discussions will provide academics and other security analysts with an opportunity to explore the differences between academic theory and the thinking of practitioners who have to implement and stand behind policy decisions. This is a follow-on project that will help build greater understanding between U.S. and Chinese experts on strategic nuclear issues by testing assumptions, correcting misperceptions, and stimulating new thinking and research in the arms control and nonproliferation community.PASC

Elementos de economía política : sexta edición notablemente corregida y aumentada con un apéndice bibliográfico

Copia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 201

Elementos de Hacienda Pública

Con un Apéndice bibliográfico de la ciencia de la Hacienda PúblicaCopia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 201