2,284 research outputs found
Introduction of functional groups on polyethylene surfaces by a carbon dioxide plasma treatment
Poly(ethylene) (PE) films were treated with a carbon dioxide (CO2) plasma to study the formation of oxygen-containing functional groups at the surface. Modified and nonmodified films were characterized by X-ray photoelectron spectroscopy (XPS) and water contact angle measurements. During the CO2 plasma treatment, the PE surface is etched and oxidized, yielding films with a very hydrophilic surface. The oxygen incorporation at the surface is fast and can be described by a combination of a zero-order incoraporation and a first-order etching process. Several oxygen functionalities such as carboxylic acid (approximately 14% of the oxygen persent), ketone/aldehyde (25%), and hydroxyl/epoxide (5-9%) groups were introduced at the surface by the plasma treatment. This was shown by using derivatization reactions for specific functional groups followed by XPS analysis. The wettability of the plasma-treated surface decreased when the films were stroed for prolonged periods of time in air. This aging process could not be completely reversed by immersion of the films in water
The Global Structure and Evolution of a Self-Gravitating Multi-phase Interstellar Medium in a Galactic Disk
Using high resolution, two-dimensional hydrodynamical simulations, we
investigate the evolution of a self-gravitating multi-phase interstellar medium
in the central kiloparsec region of a galactic disk. We find that a
gravitationally and thermally unstable disk evolves, in a self-stabilizing
manner, into a globally quasi-stable disk that consists of cold (T < 100 K),
dense clumps and filaments surrounded by hot (T > 10^4 K), diffuse medium. The
quasi-stationary, filamentary structure of the cold gas is remarkable. The hot
gas, characterized by low-density holes and voids, is produced by shock
heating. The shocks derive their energy from differential rotation and
gravitational perturbations due to the formation of cold dense clumps. In the
quasi-stable phase where cold and dense clouds are formed, the effective
stability parameter, Q, has a value in the range 2-5. The dynamic range of our
multi-phase calculations is 10^6 - 10^7 in both density and temperature. Phase
diagrams for this turbulent medium are analyzed and discussed.Comment: 10 pages, 3 figures, ApJ Letters in press (vol. 516
Mincer Earnings Functions for the Netherlands 1962-2012
We extract estimation results on the Mincer earnings function from four earlier studies and add new results from a recent dataset. We check for differences related to differences in earnings concepts and in sampling frame, to reduce bias in intertemporal comparison. Jointly, the studies show a clear U-shaped development in the rate of return to education from 1962 to 2012, with a bottom in the 1980s. We explain this from Tinbergens’s race between suppy and demand (schooling and technology) and suggest this may be a widespread international pattern. Returns to potential experience show no marked time trend. The paper has been presented at the CPB-OCW Workshop “Returns to education: research and policy”, The Hague, December 17 2015. We are grateful to Bas ter Weel and Harry Patrinos for comments on an earlier version and to Wiljan van den Berge and Dinand Webbink for providing us with their data. We also thank two anonymous referees for useful suggestions
The value of winning: endorsement returns in individual sports
Using the results of 1068 different golf, tennis, and track and field (in particular: running) events, this paper examines the relation between athlete performance and stock returns of firms endorsed by athletes. We find that a tournament victory is associated with significant and positive market-adjusted stock returns for the endorsed clothing brand. Regression analysis reveals that winning is associated with a more positive price reaction than finishing as runner-up. In addition, we find that returns after a victory are significantly higher for endorsed clothing brands than for equipment brands. We did not detect return differences between superstars and regular athletes, nor between frequently endorsed brands and less commonly endorsed brands
Provision and need of HIV/AIDS services in the City of Tshwane Metropolitan Municipality, 2010
Objectives. To determine the need for HIV/AIDS service provision in the City of Tshwane Metropolitan Municipality (CTMM), especially in municipal areas. Methods. The Foundation for Professional Development initiated the Compass Project. Using a questionnaire, data were collected during May - June 2010 from organisations providing HIV/AIDS services in the CTMM (organisational information and types of HIV/AIDS services). The need for HIV counselling and testing (HCT), antiretroviral treatment (ART), prevention of mother-tochild transmission (PMTCT), and care for orphans and vulnerable children (OVC) was estimated using data from various sources. Results. A total of 447 service providers was included in the study: 72.3% non-governmental organisations (NGOs); 18.1% in the public sector; 5.1% in the private sector; and 4.5% faithbased organisations. The majority of the prevention- (70.2%) and support-related services (77.4%) were provided by NGOs, while the majority of treatment-related services originated from the public sector (57.3%). Service need estimates included: HCT – 1 435 438 adults aged 15 - 49 years (11 127/service provider); total ART – 75 211 adults aged 15+ years (1 213/service provider); ART initiation – 30 713 adults aged 15+ years (495/service provider); PMTCTHCT – 30 092 pregnant women (510/service provider); PMTCTART – 7 734 HIV+ pregnant women (221/service provider); and OVC care – 54 590 children (258/service provider). Conclusions. Service gaps remain in the provision of HCT, PMTCT-ART and OVC care. ART provision must be increased, in light of new treatment guidelines from the Department of Health.S Afr Med J 2012;102:44-4
Tunneling and Drilling for OTEC Cold Water Pipes
This report summarizes the results of a study to determine the feasibility of using a tunnel or large-diameter drilled shaft as a conduit for transporting cold water from an ocean depth of 2000 ft to an ocean thermal energy conversion (OTEC) plant located on shore. The report identifies five possible cold water pipe (CWP) approaches that are dependent on the geologic formation and hydrology of the site. For this survey, the site under consideration is Keahole Point on the west coast of the big island of Hawaii. The site was chosen because of the easy access to deep cold water provided by the steep offshore slope, the proximity to air and sea transportation, and the availability of land. The survey concludes that although many site-specific factors must be considered, tunneling or drilling is in general a viable option for meeting the long-term OTEC cost goals. This study was carried out for the United States Department of Energy (DOE) by the Energy Technology Engineering Center (ETEC) as part of the OTEC Cold Water Pipe Technology program.Prepared for the United States Department of Energy, Ocean Engineering Technology Division, under Contract Number DE-AC03-76-SF00700, Task 43532-6530
Sorting Around the Discontinuity Threshold: The Case of a Neighbourhood Investment Programme
This paper investigates the empirical validity of the setup of a large-scale government neighbourhood investment programme in the Netherlands. Selection of neighbourhoods into the programme was determined by a measure of neighbourhood quality. At first sight this is a textbook example for the application of a regression discontinuity design to estimate the causal effect of the programme on neighbourhood outcomes. Neighbourhoods close to the threshold should be similar before the programme starts. However, at the discontinuity threshold we observe a surprisingly large gap in the share of non-Western immigrants between neighbourhoods that were selected into the programme and neighbourhoods that were not. In addition, there is non-compliance with the assignment rule based on the quality index. The pattern of non-compliance is consistent with investing in neighbourhoods with a high share of non-Western immigrants. Finally, the way in which neighbourhoods were defined could be a likely explanation for the imbalance in the share of non-Western immigrants at the discontinuity threshold
Moral dilemmas in contact-based care:The relevance of Moral Case Deliberation for forensic psychiatry
Currently, forensic psychiatry shows a shift from a control-based to a contact-based approach. Working from contact may, however, entail new moral questions and dilemmas. How to secure safety when focusing on contact? Does contact imply being physically close to the patient, or should one refrain from intimate relations? In order to help care professionals to deal with these moral issues, clinical ethics support can be useful. A specific approach in clinical ethics support is moral case deliberation (MCD). An MCD is a structured dialogue between professionals on a moral issue they experience in practice, structured by a conversation method and guided by a facilitator. In this article, we describe the background and procedures of MCD. Furthermore, we present a case example in which care professionals reflect on the moral question of whether provision of care in forensic psychiatry may entail physical closeness. The MCD shows that an open conversation results in a better understanding of different perspectives and creates the basis for finding a joint way to proceed in the case. We conclude that MCD can enable professionals to reflect on moral issues and develop shared values in forensic psychiatry
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