1,743 research outputs found
Grensoverschrijdend inlenen van arbeid in de agrarische sector:een branche-impressie
Product- en diensteninnovatie in internationale arbeidsbemiddeling worden bemoeilijkt door onduidelijkheid en onzekerheid. In dit working paper van het Expertisecentrum Grensoverschrijdend Inlenen van Arbeid, wordt beschreven wat de huidige stand van zaken is in de agrarische sector. Ook worden relevante cijfers gepresenteerd over de agrarische arbeidsmarkt en komen ontwikkelingen in de bedrijfstak op het gebied van grensoverschrijdend inlenen van arbeid aan de orde. Het paper eindigt met een vooruitblik op de verdere ontwikkeling van (tijdelijke arbeids)migratie in de agrarische sector
Minimum power design of RF front ends
This thesis describes an investigation into the design of RF front ends with minimum power dissipation. The central question is: "What are the fundamental limits for the power dissipation of telecommunication front ends, and what design procedures can be followed that approach these limits and, at the same time, result in practical circuits?" After a discussion of the state of the art in this area, the elementary operations of a front end are identified. For each of these elementary operations, the fundamental limits for the power dissipation are discussed, divided into technology imposed limits and physics imposed limits. A traditional DECT front end design is used to demonstrate the large difference between the fundamental limits and the power dissipation of existing circuits. To improve this situation, first the optimum distribution of specifications across individual subcircuits needs to be determined, such that the requirements for a specific system can be fulfilled. This is achieved through the introduction of formal transforms of the specifications of subcircuits, which correspond with transforms of the subcircuit itself. Using these transforms, the optimum distribution of gain, noise, linearity and power dissipation can be determined. As it turns out, this optimum distribution can even be represented by a simple, analytical expression. This expression predicts that the power dissipation of the DECT front end can be reduced by a factor of 2.7 through an optimum distribution of the specifications. Using these optimum specifications of the subcircuits, the boundaries for further power dissipation reduction can be determined. This is investigated at the system, circuit and technology level. These insights are used in the design of a 2.5GHz wireless local area network, implemented in an optimized technology ("Silicon on Anything"). The power dissipation of the complete receiver is 3.5mW, more than an order of magnitude below other wireless LAN receivers in recent publications. Finally, the combination of this minimum power design method with a platform based development strategy is discussed
Cultural Competence in School Social Work: A Personal and Professional Learning Curve
As the nation grows more diverse and the numbers of American youth with mental illness climb, the importance of culturally responsive school social work practice is critical. Research suggests cultural competence is a fluid concept but one that improves service and client outcomes. Studies link cultural competence to licensure levels and practice experience, as well as primary social work competencies. Studies also indicate practitioners consider professional development and a supportive school environment to aid in cultural competency efforts, while societal influences and personal lack of knowledge and self-awareness can impede the process. This study obtained primary data from a purposive sample (n = 7) of licensed school social workers in an urban school district. A semi-structured interview afforded quantitative and qualitative data regarding demographics and perceptions on knowledge, skills, influences, and evaluative measures deemed relevant to cultural competence. The findings echo previous research that suggests cultural competence involves adopting key social work principles and therapeutic skills in the aim to meet individual client needs, rather than those assumed to belong to an overt cultural group. Supports were seen as generally stemming from more immediate factors, while barriers were seen as stemming from larger, more removed influences; this also supports previous research. This study suggests social workers’ abilities to model cultural responsiveness and a willingness to assess their own competencies in diverse ways are important practice components. It also highlights the need for more balanced, behaviorally based cultural competency measures. Future research to explore clients’ perspectives of practitioners’ cultural competence and relevant case studies is recommended. While this study’s qualitative nature allowed for personal insight and experiences, it remains highly exploratory
Cultural Competence in School Social Work: A Personal and Professional Learning Curve
As the nation grows more diverse and the numbers of American youth with mental illness climb, the importance of culturally responsive school social work practice is critical. Research suggests cultural competence is a fluid concept but one that improves service and client outcomes. Studies link cultural competence to licensure levels and practice experience, as well as primary social work competencies. Studies also indicate practitioners consider professional development and a supportive school environment to aid in cultural competency efforts, while societal influences and personal lack of knowledge and self-awareness can impede the process. This study obtained primary data from a purposive sample (n = 7) of licensed school social workers in an urban school district. A semi-structured interview afforded quantitative and qualitative data regarding demographics and perceptions on knowledge, skills, influences, and evaluative measures deemed relevant to cultural competence. The findings echo previous research that suggests cultural competence involves adopting key social work principles and therapeutic skills in the aim to meet individual client needs, rather than those assumed to belong to an overt cultural group. Supports were seen as generally stemming from more immediate factors, while barriers were seen as stemming from larger, more removed influences; this also supports previous research. This study suggests social workers’ abilities to model cultural responsiveness and a willingness to assess their own competencies in diverse ways are important practice components. It also highlights the need for more balanced, behaviorally based cultural competency measures. Future research to explore clients’ perspectives of practitioners’ cultural competence and relevant case studies is recommended. While this study’s qualitative nature allowed for personal insight and experiences, it remains highly exploratory
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Suzuki-Miyaura mediated biphenyl synthesis: a spotlight on the boronate coupling partner
The biaryl motif is found in many natural and synthetic products that display a wide range of biological activities. This explains why biphenyls are widely encountered in medicinal chemistry as a privileged scaffold. The palladium-catalysed Suzuki-Miyaura (SM) coupling is one of the most important and efficient strategies for the synthesis of symmetrical and unsymmetrical biaryl compounds; the arylboronic acid or ester is a key partner in this coupling reaction.
This work presents the synthesis of a library of new molecules containing the biphenyl scaffold; o-, m- and p-(bromomethyl)phenylboronic acid pinacol esters, 2a-c, were selected as coupling partners. Nucleophilic substitution of the bromide was carried out with amine, thiol, alcohol or phenol nucleophiles. Supported reagents and microwave assisted organic synthesis conditions were employed to enhance this chemistry and made it amenable to parallel synthesis. The resulting arylboronates were used in SM coupling reactions in order to obtain a range of biphenyls.
The use of Boc-piperazine as a nucleophile in the SN2 reaction, with 2a-c, and 1-bromo-, 2-, 3- or 4-nitrobenzene or 2-bromo-5-nitropyridine as aryl halides in the SM coupling reaction, allowed two other points of functionalisation to be added to the biaryl motif.
The conditions for the SM coupling of mercaptomethylphenylboronic esters and orthosubstituted methylphenylboronic esters were optimised in order to broaden the scope of the biaryl library.
Phosphines were found to be good nucleophiles in the SN2 reaction with 2a-c. A Wittig reaction was performed with the resulting phosphonium arylboronates in order to synthesise arylboronic esters containing an alkene function prior the reduction of the resulting double bond of the stilbene derivatives and realising a SM coupling to synthesise arylethylbiphenyls.
The stilbene derivatives were also synthesised by using the olefin cross-metathesis reaction of 4-vinylphenylboronic acid pinacol ester.
A solid state crystallographic study was undertaken on a small library of methylbiphenylamides to compare the crystal structures of isomers or biphenyls with different functional groups
Optimizing RF front ends for low power
This paper discusses optimizations for the power dissipation of RF front ends in portable wireless devices. A breakthrough in power dissipation can be achieved by simultaneously optimizing the antenna interface, circuits, and IC technology of such devices. A model that predicts the minimum power dissipation of a front end for both short-range and long-range connections will be introduced. Using these models, the impact of the antenna interface on the power dissipation will be assessed. Using two antennas with equal gain combining, a typical power dissipation reduction of 2.5 to 30 times can be achieved. Using high-impedance circuits for short-range systems in combination with silicon-on-anything technology, a further reduction of power dissipation by up to one order of magnitude can be realize
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