Controlled Manipulation of Individual Vortices in a Superconductor

We report controlled local manipulation of single vortices by low temperature magnetic force microscope (MFM) in a thin film of superconducting Nb. We are able to position the vortices in arbitrary configurations and to measure the distribution of local depinning forces. This technique opens up new possibilities for the characterization and use of vortices in superconductors

Wetenschapswinkel Wageningen UR : 25 jaar! : jubileummagazine 25 jaar Wetenschapswinkel Wageningen University & Research Centre

Dertig jaar geleden hielden studenten vier weken lang het hoofdgebouw van de Landbouwhogeschool bezet. Ze wilden niet alleen onderzoek doen voor bedrijven. En niet alleen onderzoek om het onderzoek. Ze wilden probleemgericht onderwijs en onderzoek. De universiteit moest er ook zijn voor die groepen in de samenleving die geen toegang hadden tot de zegeningen van het wetenschappelijk onderzoek. Een groepje studenten en medewerkers van de hogeschool stak tijdens die bezetting de koppen bij elkaar om de voorloper van de Wetenschapswinkel in Wageningen op te richten. De Wetenschapswinkel wilde geen rapportjes opleveren die onderin de la zouden verdwijnen. We besteedden daarom veel tijd aan het vertalen van de vraag waar de ‘klant’ mee binnenkwam naar een onderzoeksvraag die de vragensteller werkelijk verder zou brengen. Nu 25 jaar later. Kennis is voor iedereen, via internet, vrij beschikbaar

Reflexivity in performative science shop projects

Science shop research projects offer possibilities for universities to engage with communities. Many science shop projects directly or indirectly intend to empower certain marginalised groups or interests within a decision-making process. In this article we argue that it is important to reflect on the role and position the researchers have in these projects. We present three science shop projects to illustrate some of the dilemmas that may arise in relation to citizen empowerment, democracy, and ethics in the field of action research and community engagement. We present reflexivity as a strategy for creating greater awareness of the power−knowledge relationship, the nature of the democratic process and the consequences of empowerment for other vulnerable groups. Keywords: Action research, community engagement, reflexivity, science sho

Beam Test of Silicon Strip Sensors for the ZEUS Micro Vertex Detector

For the HERA upgrade, the ZEUS experiment has designed and installed a high precision Micro Vertex Detector (MVD) using single sided micro-strip sensors with capacitive charge division. The sensors have a readout pitch of 120 microns, with five intermediate strips (20 micron strip pitch). An extensive test program has been carried out at the DESY-II testbeam facility. In this paper we describe the setup developed to test the ZEUS MVD sensors and the results obtained on both irradiated and non-irradiated single sided micro-strip detectors with rectangular and trapezoidal geometries. The performances of the sensors coupled to the readout electronics (HELIX chip, version 2.2) have been studied in detail, achieving a good description by a Monte Carlo simulation. Measurements of the position resolution as a function of the angle of incidence are presented, focusing in particular on the comparison between standard and newly developed reconstruction algorithms.Comment: 41 pages, 21 figures, 2 tables, accepted for publication in NIM

Physicochemical surface properties of brewing yeast influencing their immobilization onto spent grains in a continuous reactor

Immobilization of brewing yeast onto a cellulosebased carrier obtained from spent grains, a brewing byproduct, by acid/base treatment has been studied in a continuously operating bubble-column reactor. The aim of this work was to study the mechanisms of brewing yeast immobilization onto spent grain particles through the information on physicochemical surface properties of brewing yeast and spent grain particles. Three mechanisms of brewing yeast immobilization onto spent grains carrier were proposed: cell-carrier adhesion, cell-cell attachment, and cell adsorption (accumulation) inside natural shelters (carrier’s surface roughness). The possibility of stable cell-carrier adhesion regarding the free energy of interaction was proved and the relative importance of longrange forces (Derjaguin-Landau-Verwey-Overbeek theory) and interfacial free energies was discussed. As for the cell-cell attachment leading to a multilayer yeast immobilization, a physicochemical interaction through localized hydrophobic regions on cell surface was hypothesized. However, neither flocculation nor chain formation mechanism can be excluded so far. The adsorption of brewing yeast inside sufficiently large crevices (pores) was documented with photomicrographs. A positive effect of higher dilution rate and increased hydrophobicity of base-treated spent grains on the yeast immobilization rate has also been found.Fundação para Ciência e Tecnologia (FCT

Carbohydrate carbon sources induce loss of flocculation of an ale-brewing yeast strain

Aims: To identify the nutrients that can trigger the loss of flocculation under growth conditions in an ale-brewing strain, Saccharomyces cerevisiae NCYC 1195. Methods and Results: Flocculation was evaluated using the method of Soares, EX. and Vroman, A. [Journal of Applied Microbiology (2003) 95, 325]. Yeast growth with metabolizable carbon sources (glucose, fructose, galactose, maltose or sucrose) at 2% (w/v), induced the loss of flocculation in yeast that had previously been allowed to flocculate. The yeast remained flocculent when transferred to a medium containing the required nutrients for yeast growth and a sole nonmetabolizable carbon source (lactose). Transfer of flocculent yeast into a growth medium with ethanol (4% v/v), as the sole carbon source did not induce the loss of flocculation. Even the addition of glucose (2% w/v) or glucose and antimycin A (0.1 mg lˉ¹) to this culture did not bring about loss of flocculation. Cycloheximide addition (15 mglˉ¹) to glucose-growing cells stopped flocculation loss. Conclusions: Carbohydrates were the nutrients responsible for stimulating the loss of flocculation in flocculent yeast cells transferred to growing conditions. The glucose-induced loss of flocculation required de novo protein synthesis. Ethanol prevented glucose-induced loss of flocculation. This protective effect of ethanol was independent of the respiratory function of the yeast. Significance and Impact of the Study: This work contributes to the elucidation of the role of nutrients in the control of the flocculation cycle in NewFlo phenotype yeast strains.Instituto Politécnico do Porto (IPP) - Fundo de Apoio à Investigação - Project P24/96 , P24/97.Programa Plurianual de Unidades de I&D-CIEA/ ISEP

End-users Compliance to the Information Security Policy: A Comparison of Motivational Factors

Business information, held within information systems, is critical for most organizations. To protect these critical information assets, security controls should be deployed which might come as a hindrance for the end-users. The Information Security Policies (ISP) give direction to their behaviors. Organizations can focus on conditions likely to promote so-called motivational factors influencing the end-users intentions to perform the desired behavior of compliance to ISP in order to protect these information assets. In total, six motivational factors, applicable to intentions on compliance, are found during research and are measured within five organizational contexts. From the measurements and analysis is learned, that the degree to which these factors relate differs per factor and per context. Two of these factors were found to always relate in such degree to compliance intentions that even without measuring the degree for a particular organization, applying these factors can be very effective for any organization or context. The other four factors have shown to be effective within particular context(s) meaning measurement of the context is needed before utilizing these factors within an organization to optimize the effect of efforts