Nuclear Charge Radii of Neutron-Deficient Lead Isotopes Beyond N=104 Midshell Investigated by In-Source Laser Spectroscopy

The shape of exotic even-mass 182–190Pb isotopes was probed by measurement of optical isotope shifts providing mean square charge radii (δ⟨r2⟩). The experiment was carried out at the isolde (cern) on-line mass separator, using in-source laser spectroscopy. Small deviations from the spherical droplet model are observed, but when compared to model calculations, those are explained by high sensitivity of δ⟨r2⟩ to beyond mean-field correlations and small admixtures of intruder configurations in the ground state. The data support the predominantly spherical shape of the ground state of the proton-magic Z=82 lead isotopes near neutron midshell (N=104)

De dubbelzinnigheid van het politieke rechts-extremisme in Vlaanderen en Nederland : een confrontatie van de ideologische standpunten van extreem-rechtse partijen en hun kiezers

Contains fulltext : 3315.pdf (publisher's version ) (Open Access

The efficiency of education in generating literacy: a stochastic frontier approach

The growing importance attached to education as a key factor to improve economic performance coupled with the persistent scarcity of resources for education makes it important that skills and literacy are produced efficiently. This paper provides an international comparison of the efficiency of literacy production. We find substantial differences between countries in levels of literacy, differences in literacy between education levels and differences in the efficiency of literacy production. There are some notable differences between more Anglo-Saxon countries and the Continental European countries. The findings suggest that in almost all countries the scope for efficiency improvements in education is large. So even without major increases in (public) funding, improvements in educational outcomes are achievable. We can get better value for the money we spend on education.

Phase transitions during membrane formation of polylactides. I. A morphological study of membranes obtained from the system polylactide-chloroform-methanol

The influence of solid-liquid demixing, liquid-liquid demixing and vitrification on the morphology of polylactide membranes has been investigated. To study the effects of crystallization of polylactides on the membrane and morphology, polylactides of varying stereoregularity were used. The polymers applied were poly--lactide (PLLA) and copolymers with different molar ratios of -lactide and -lactide [poly-L95/D5-lactide (PLA95), poly-L80/D20-lactide (PLA80) and poly-L50/D50-lactide (PDLLA)]. Solutions of polylactides in chloroform cast on a glass plate were immersed in methanol. From solutions containing the slowly crystallizing PLA80 or uncrystallizable PDLLA porous membranes were obtained if the phase separated system was removed from the nonsolvent bath within a few hours after immersion. After longer equilibration times in methanol the structure collapsed. The swelling in the nonsolvent methanol was too high to allow stabilization of the liquid-liquid demixed structure by vitrification. Stable membranes were easily obtained with more rapidly crystallizing polymers like PLLA. Casting solutions with low PLLA concentrations gave membranes with a cellular morphology due to liquid-liquid demixing by nucleation and growth of a polymer poor phase. Crystallization only played a role in the fixation of the liquid-liquid demixed structure. At increasing PLLA concentrations the demixing sequence gradually reversed to crystallization followed by liquid-liquid demixing. In these cases membranes with porous spherulites or spherulites surrounded with a cellular layer were obtained

A morphological study of membranes obtained from the systems polylactide-dioxane-methanol, polylactide-dioxane-water and polylactide-N-methyl pyrrolidone-water

The influence of liquid-liquid demixing, solid-liquid demixing, and vitrification on the membrane morphologies obtained from several polylactide-solvent-nonsolvent systems has been investigated. The polymers investigated were the semicrystalline poly-L-lactide (PLLA) and the amorphous poly-DL-lactide (PDLLA). The solvent-nonsolvent systems used were dioxane-water, N-methyl pyrrolidone-water and dioxane-methanol. For each of these systems it was attempted to relate the membrane morphology to the ternary phase diagram at 25°C. It was demonstrated that for the amorphous poly-DL-lactide the intersection of a glass transition and a liquid-liquid miscibility gap in the phase diagram was a prerequisite for the formation of stable membrane structures. For the semicrystalline PLLA a wide variety of morphologies could be obtained ranging from cellular to spherulitical structures. For membrane-forming combinations that show delayed demixing, trends expected on the basis of phase diagrams were in reasonable agreement with the observed membrane morphologies. Only for the rapidly precipitating system PLLA-N-methyl pyrrolidone-water were structures due to liquid-liquid demixing obtained when structures due to solid-liquid demixing were expected. Probably, rapid precipitation conditions promote solid-liquid demixing over liquid-liquid demixing, because the activation energy necessary for liquid-liquid demixing is lower than that for crystallization

The Living Rainforest Sustainable Greenhouses

The Living Rainforest (www.livingrainforest.org) is an educational charity that uses rainforest ecology as a metaphor for communicating general sustainability issues to the public. Its greenhouses and office buildings are to be renovated using the most sustainable methods currently available. This will be realised through construction of a high insulating greenhouse covering with a k-value of less than 2 Wm-2K-1, passive seasonal storage of excess summer solar energy in the ground by a ground source heat exchanger and exploitation of this low grade solar energy for heating in winter by a heat pump. In winter the heat pump will produce cold water to cool the ground allowing a passive cooling function in summer via the GSHE. It will be demonstrated that a GSHE is an alternative for an open aquifer in regions with no aquifer availability. The heat pump will deliver the heating baseload, the peak load will be delivered by a biomass boiler, fired with locally-sourced low-cost wood chips. It is expected that the energy saving will be about 75%, resulting in a major cost reduction. The low k-value of the covering is linked to a light transmission of 75 %. This is high enough for the demands of the vegetation in The Living Rainforest. Because the inner greenhouse climate demands are comparable to that of ornamentals, the results will be applicable to commercial ornamental production. In future low k-value coverings will also be available with high light transmission, allowing wider application of the results. This paper focuses on the correlation between k-value, light transmission and energy demand in order to investigate the trade-off between light transmittance (a major energy gain) and heat loss. The effects of these design parameters on storage and harvesting capacity are also considered but appear to have a low sensitivity. The renovated greenhouse site at The Living Rainforest will show that new greenhouses and ecology can be linked to sustainability and this will be communicated and demonstrated to the public

Hoe zwart is Vlaanderen? Een exploratief onderzoek naar uiterst-rechtse denkbeelden in Vlaanderen in 1991

Contains fulltext : 3308.pdf (publisher's version ) (Open Access

Formation of porous membranes for drug delivery systems

Highly crystalline porous hollow poly (-lactide) (PLLA) fibres suitable for the delivery of various drugs were obtained using a dry-wet spinning process. The pore structure of the fibres could be regulated by changing the spinning systems and spinning conditions. Using the spinning system PLLA-dioxane-water, fibres with a dense toplayer and a spongy sublayer were obtained. The spinning system PLLA-chloroform/toluene-methanol yielded fibres with a very open porous structure. The membrane formation of the former system probably occurs by liquid-liquid demixing followed by crystallization of the polymer rich phase. In the membrane formation process of the spinning system, PLLA-chloroform/toluene-methanol crystallization probably plays a dominant role. The membrane formation process will be related to basic principles of phase separation. The fibres are suitable for the long term zero order delivery of the contraceptive 3-ketodesogestrel and the short term zero order delivery of the cytostatic agent, cisplatin. The drugs are released by dissolution of the drug crystals in the fibre core followed by diffusion through the membrane structure. Short term release of adriamycin could be obtained through an adsorption-desorption mechanism. The pore structures of the fibres have a large influence on the release rates of the drugs investigated. When fibres with dense toplayers were used, low release rates of drugs were observed whereas fibres with well interconnected pore structures over the fibre wall showed very high release rates

Measuring exposure to bullying at work:The validity and advantages of the latent class cluster approach

This paper addresses the construct and predictive validity of two methods for classifying respondents as victims of workplace bullying. Although bullying is conceived as a complex phenomenon, the dominant method used in bullying surveys, the operational classification method, only distinguishes two groups: victims versus non-victims. Hence, the complex nature of workplace bullying may not be accounted for. Therefore a latent class cluster approach is suggested to model the data, which was obtained by using the Negative Acts Questionnaire (NAQ) administered to employees in Belgium (n=6,175). Latent class modelling is a method of analysis that does not appear to have been used in occupational health psychology before. In this study, six latent classes emerged: “not bullied,” “limited work criticism,” “limited negative encounters,” “sometimes bullied,” “work related bullied,” and “victims.” The results show that compared to the traditional operational classification method, the latent class cluster approach shows higher construct and higher predictive validity with respect to self-assessments and indicators of strain and well-being at work. The consequences of these results for theory, future research, and practice are discussed

The cognitive/affective distinction of job insecurity: Validation and differential relations

Job insecurity as a work-related stressor is well established through three decades of research. It has been related to outcomes such as decreased job satisfaction, organisational commitment and performance as well as increased ill-health and organisational turnover. However, some important conceptual and theoretical issues are still under discussion, with implications for the measurement of the construct. We administered a short version of the measure of job insecurity originally devised by De Witte (2000), which distinguishes between cognitive and affective job insecurity. Data on job satisfaction, commitment, psychological ill-health and emotional exhaustion were also gathered from employees in a variety of South African organisations (N=1925) by means of anonymous surveys. Exploratory and confirmatory factor analyses revealed that the cognitive and affective dimensions of job insecurity could be distinguished in this sample of South African employees, and the two dimensions evidenced adequate reliability. Equivalence analyses showed that the measurement properties of the scale were invariant across various demographic groups. The relationships with outcome variables were investigated by means of correlations and regression analyses. Cognitive job insecurity was predictive of all outcome variables, whereas affective job insecurity primarily played a role for emotional exhaustion. Norm data concerning levels of cognitive and affective job insecurity are presented to guide future South African studies.Key words: Job insecurity, job satisfaction, validation, equivalence analysis, factorial invarianc