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231.
Elisabeth Hovdhaugen 《Journal of Education & Work》2015,28(6):631-651
There are many possible reasons why students leave university prior to degree completion, and one of the more commonly cited is being employed while studying. This paper analyses the impact of employment status on dropout rates using survival analysis. It finds that employment status does have an impact on dropout rates; students who work full time alongside studying full time are less likely to complete their programme than students working short part-time or not working at all. However, it seems as if there is a threshold to how much students can work, as working more than 20?h a week (long part-time work) increase the risk of dropout as much as full-time work. Integrating employment status into the analysis does not change the effect of variables known to have an influence on dropout, such as grades, gender and social background, but it contributes to further explain who are at risk of dropout. This implies that models for dropout and retention must also take such external factors into account, not just consider what happens at university, as in model of student departure. 相似文献
232.
233.
Fanny?TamkeEmail author Elisabeth?Aram Stephan?Mücke 《Zeitschrift für Erziehungswissenschaft》2003,6(4):571-589
Der Beitrag thematisiert jugendliche Orientierungsmuster zur Ausgestaltung der Lebensphase Jugend und deren Ver?nderung über
die Zeit. Diese entstehen im komplexen Zusammenhang von wahrgenommenen Ressourcen, Einstellungen und Erwartungen Jugendlicher
im Hinblick auf die Anforderung der Bew?ltigung von Entwicklungsaufgaben. Zur Abbildung dieser Muster wird auf zwei zentrale
Dimensionen zurückgegriffen: auf Entfaltungsorientierung, die den Moratoriumsgedanken, und Entwicklungsorientierung, die den
transitiven Charakter der Jugendphase widerspiegelt. Aus der Kombination der Orientierungen Entwicklung und Entfaltung im
Anschluss an die Verknüpfung des Transitions-und Moratoriumsgedankens lassen sich vier Typen ableiten. Die Zugeh?rigkeit zu
einem Typ ist nicht als statisch zu fassen, sondern ver?ndert sich entsprechend der zunehmenden Bew?ltigung von Entwicklungsaufgaben.
Die Ergebnisse veranschaulichen die weitreichende Bedeutung beruflicher Orientierungen Jugendlicher im Zusammenhang mit dem
bevorstehenden übergang in den Beruf, die gleichsam Auswirkungen für den gesamten Komplex jugendlicher Orientierungsmuster
(Typen) zur Gestaltung der Jugendphase zeitigen. 相似文献
234.
Ilse Johanna Elisabeth Flink Solange Marie Odile Mbaye Simon Richard Baye Diouf Sophie Baumgartner Pinar Okur 《Sex education》2018,18(1):32-46
This study identifies lessons learned from a collaboration between a child telephone helpline and sexual and reproductive health and rights (SRHR) organisations in Senegal established in the context of an SRHR programme for young people. We assessed how helpline operators are equipped to address sexual health and rights issues with young people, what the relevant skills of operators are, and to what extent referral to sexual and reproductive health (SRH) service providers took place. A documentary review, a vignette study and interviews with six key informants and all seven operators took place. The collaboration led to promising initiatives, such as the provision of SRH training, the exchange of staff, referral to SRH service providers. However, the counselling advice provided by operators was not always in line with the rights-based approach and responses were influenced by underlying norms concerning young people’s sexuality. Additionally, concerns about confidentiality were noted. The collaboration was an innovative attempt to respond to young people’s limited access to SRHR information and services but there is a need for more in-depth training of helpline operator’s skills and the development of a standardised rights-based counselling manual. 相似文献
235.
Elisabeth Charron 《科学教学研究杂志》1991,28(7):609-618
During recent decades there has been little research on social or cultural factors affecting science education. Recent literature reviews have indicated that of the studies addressing such factors, most focus on broad sociodemographic variables such as socioeconomic status, gender, ethnicity, and region. There is a need for research that depicts better-differentiated social contexts for science education in their full complexity. Social scientists from several other fields have recently developed a promising model for research in context. Three critical conceptual and methodological strands of the model are discussed, along with their implications for science education research. 相似文献
236.
The acquisition of a reading vocabulary for abstract and concrete words was examined in 62 second-grade children. Words had been learned as part of a basal reader program or as part of outside reading. Word recognition speed and reading accuracy were examined for abstract and concrete words using lexical decision and word naming tasks. The size of the concreteness effect was similar for both processing tasks. In neither task did concreteness influence reaction times, but abstract words were read with less accuracy than concrete words in both tasks. Further, these concreteness effects in reading accuracy were larger for words that were part of a basal reading program than for words acquired during free reading. We conclude that word meaning influences the entry of words at a time when children are developing a sizeable reading vocabulary. 相似文献
237.
Investigating the Educational Implications of Embodied Cognition: A Model Interdisciplinary Inquiry in Mind,Brain, and Education Curricula 下载免费PDF全文
Elisabeth Osgood‐Campbell 《Mind, Brain, and Education》2015,9(1):3-9
Much educational neuroscience research investigates connections between cognition, neuroscience, and educational theory and practice without reference to the body. In contrast, proponents of embodied cognition posit that the bodily action and perception play a central role in cognitive development. Some researchers within the field of Mind, Brain, and Education (MBE) explore this theory by researching the impact of sensorimotor activity on academic competencies such as language comprehension, mathematics, and scientific thinking. In this article, I call for this work to be highlighted more centrally in MBE training programs. Toward this end, I model an investigation of the concept of embodied cognition that can be used in MBE curricula with a dual purpose: to train future practitioners in the seminal metaphor of mind as an embodied system, and to demonstrate effective interdisciplinary research, which is critical to advancing the field of Mind, Brain, and Education. 相似文献
238.
Elisabeth Gareis 《Communication Teacher》2013,27(2):39-43
Objective: To explore and to arrive at a personal position vis-à-vis the concepts of universalism and relativism as they apply to gender issues Course: Intercultural communication 相似文献
239.
This study explored bilingual school psychologists' assessment practices with students identified as English language learners (ELL). One thousand bilingual National Association of School Psychologist members were recruited nationwide, and 276 participated. Among those conducting language proficiency assessments of ELLs, many (58%) use comprehensive methods across four domains of language use. Participants generally use multifaceted assessment approaches and most (84.1%) assess acculturation as part of the assessment battery. Although few use interpreters, those who did reported a mix of best practices and discouraged practices in their use. Multiple regression results showed that engaging in continuing education activities about assessing ELLs predicted “best practices” when assessing language proficiency, selecting and using measures with ELLs with whom they share a second language, and using interpreters. A relationship was also found between engaging in applied preservice training with bilingual supervision and best practice behaviors assessing student acculturation. © 2010 Wiley Periodicals, Inc. 相似文献
240.
Olivier Ducloux Elisabeth Galopin Farzam Zoueshtiagh Alain Merlen Vincent Thomy 《Biomicrofluidics》2010,4(1)
A droplet-based micro-total-analysis system involving biosensor performance enhancement by integrated surface-acoustic-wave (SAW) microstreaming is shown. The bioreactor consists of an encapsulated droplet with a biosensor on its periphery, with in situ streaming induced by SAW. This paper highlights the characterization by particle image tracking of the speed distribution inside the droplet. The analyte-biosensor interaction is then evaluated by finite element simulation with different streaming conditions. Calculation of the biosensing enhancement shows an optimum in the biosensor response. These results confirm that the evaluation of the Damköhler and Peclet numbers is of primary importance when designing biosensors enhanced by streaming.It has been pointed out that biosensing performances can be limited by the diffusion of the analytes near the sensing surface.1 In the case of low Peclet number hydrodynamic flows, typical of microfluidic systems, molecule displacements are mainly governed by diffusive effects that affect time scales and sensitivity. To overcome this problem, the enhancement of biosensor performance by electrothermal stirring within microchannels was first reported by Meinhart et al.2 Other authors3, 4 numerically studied the analyte transport as a function of the position of a nanowire-based sensor inside a microchannel, stressing on the fact that the challenge for nanobiosensors is not the sensor itself but the fluidic system that delivers the sample. Addressing this problem, Squires et al.5 developed a simple model applicable to biosensors embedded in microchannels. However, the presented model is limited to the case of a steady flow. The use of surface-acoustic waves (SAWs) for stirring in biomicrofluidic and chemical systems is becoming a popular investigation field,6, 7, 8, 9 especially to overcome problems linked to steady flows by enhancing the liquid∕surface interaction.1, 10, 11 The main challenges that need to be addressed when using SAW-induced stirring are the complexity of the flow and its poor reproducibility. However, some technical solutions were proposed to yield a simplified microstreaming. Yeo et al. presented a centrifugation system based on SAW that produces the rotation of the liquid in a droplet in a reproducible way by playing on the configuration of the transducers and reflectors,12 and presented a comprehensive experimental study of the three-dimensional (3D) flow that causes particle concentration in SAW-stirred droplets,13 revealing the presence of an azimuthal secondary flow in addition to the main vortexlike circular flow present in acoustically stirred droplets. The efficiency of SAW stirring in microdroplets to favorably cope with mass transport issues was finally shown by Galopin et al.,14 but the effect of the stirring on the analyte∕biosensor interaction was not studied. It is expected to overcome mass transport limitations by bringing fresh analytes from the bulk solution to the sensing surface.The studied system, described in Fig. Fig.1,1, consists of a microliter droplet microchamber squeezed between a hydrophobic piezoelectric substrate and a hydrophobic glass cover. Rayleigh SAWs are generated using interdigitated transducers (interdigital spacing of 50 μm) laid on an X-cut LiNbO3 substrate.1, 15, 16 The hydrophobicity of the substrate and the cover are obtained by grafting octadecyltrichlorosilane (OTS) self-assembled monolayers (contact angle of 108° and hysteresis of 9°). To do so, the surface is first hydroxylized using oxygen plasma (150 W, 100 mT, and 30 sccm3 O2) during 1 min and then immersed for 3 h into a 1 mM OTS solution with n-hexane as a solvent.Open in a separate windowFigure 1(a) General view of the considered system. (b) Mean value of the measured speeds within the droplet as a function of the inlet power before amplification.When Rayleigh waves are radiated toward one-half of the microchamber, a vortex is created in the liquid around an axis orthogonal to the substrate due to the momentum transfer between the solid and the liquid. This wave is generated under the Rayleigh angle into the liquid.Speed cartographies of the flow induced in the droplet are realized using the particle image tracking technique for different SAW generation powers. To do so, instantaneous images of the flow are taken with a high-speed video camera at 200 frames∕s and an aperture time of 500 μs on a 0.25 μl droplet containing 1 μm diameter fluorescent particles. Figure Figure11 shows the mean speed measured in the droplet as a function of the inlet power. The great dependence of the induced mean speed with the SAW power enables a large range of flow speeds in the stirred droplet. Moreover, the flow was visualized with a low depth of field objective. It was found to be circular and two dimensional (2D) in a large thickness range of the droplet.The binding of analytes to immobilized ligands on a biosensor is a two step process, including the mass transport of the analyte to the surface, followed by a complexation step,(1)with km as the constant rate for mass transport from and to the sensor, and ka and kd as the constant rates of association and dissociation of the complex.At the biosensor surface, the reaction kinetics consumes analytes but their transport is limited by diffusive effects. In this case, the Damköhler number brings valuable information by comparing these two effects. Calling the characteristic time of reaction and diffusion, respectively, τC and τM, the mixing time in diffusion regime can be approximated by τM≈h2∕D with D as the diffusion coefficient and h a characteristic length of the microchannel. Calling RT the ligand concentration on the surface in mole∕m2, the Damköhler number (Da) can be written as(2)Depending on the type of reaction, the calculation of Da helps determine if a specific biointeraction will benefit from a mass SAW-based microstreaming. If the Damköhler number is low, the reaction is slow compared to mass transport and the reaction will not significantly benefit from microstirring. For example, the hybridization of 19 base single stranded DNA in a microfluidic system with a characteristic length of 500 μm is characterized by a Damköhler number of 0.07 and is therefore not significantly influenced by mass transport. On the contrary, the binding of biotin to immobilized streptavidin is characterized by a Da number of approximately 104. In this case, the stirring solution will significantly improve the reaction rate.COMSOL numerical simulations were carried out to study the efficiency of the SAW stirring in the case of a droplet-based microbioreactor with a diameter of 1 mm. Assuming a 2D flow, the simulated model takes into account the convective and diffusive effects in the analyte-carrying fluid and the binding kinetics on the biosensor surface. This approach was thoroughly developed by Meinhart et al.2On the biosensor surface, the following equations are solved:(3)(4)with c as the local concentration of analytes in the droplet and B as the surface concentration of bound analytes on the biosensor surface. Simulation results show that a depleted zone is formed near the biosensor in the case of an interaction without stirring. This zone is characterized by a low concentration of analytes and results from the trapping of analytes on the biosensor surface, thus creating a concentration gradient on the vicinity of the biosensor. When stirring is applied, the geometry of the depleted zone is modified, as it is pushed in the direction of the flow. The geometry of the depleted zone then depends on many parameters, among which the diffusion coefficient D, the speed distribution of the flow (not only near the biosensor but also in the whole microfluidic system), and the reaction kinetics on the biosensor. In our case, which is assimilated to a simple circular flow, the depleted zone reaches a permanent state consisting of an analyte-poor layer situated in the exterior perimeter of the stirred droplet. The diffusion of analytes is then limited again by diffusion from the inner part of the droplet toward its exterior perimeter (see Fig. Fig.22).Open in a separate windowFigure 2(a) Mean concentration of bound analytes vs time for different mean flow speeds. (b) The obtained concentration profiles with and without circular stirring, t=10 000 s.The initial analyte and receptor concentrations are, respectively, 0.1 nM in the solution and 3.3×10−3 nM m on the biosensor surface, the diffusion coefficient is D=10−11 m2 s−1, and the reaction constants are ka=106 M−1 s−1 and kd=10−3 s−1. Simulations show that the mean concentration of bound analytes highly increases with the flow speed, improving the efficiency of the biosensing device. To evaluate the benefits of in situ microstreaming with SAW, the same simulations were conducted for Da numbers ranging from 104 to 108 M−1∕s, by ranging the diffusion coefficient from 4×10−12 to 4×10−9 m2∕s, and the association coefficient ka from 104 to 108 M−1∕s. The enhancement factor of analyte capture, defined as the ratio of the binding rate with streaming B and the binding rate without streaming B0, is plotted in Fig. Fig.33 for different values of Da. Calculations are done in the case of a mean flow speed of 0.5 mm∕s.Open in a separate windowFigure 3(a) Enhancement factor (defined as the ratio between binding rate with streaming B and binding rate without streaming B0) for different Damkhöler numbers and (b) normalized enhancement factor for different Peclet numbers.One can notice the saturation of the enhancement factor curve for large value of Da to the value of 3.5 for high Da. This can be explained by the fact that for large ka∕Da ratios, the analytes, which normally require penetration in the depleted zone by diffusion, do not have time to interact with the biosensor when they pass in the vicinity of its surface. The efficiency of the streaming is then reduced for large values of Da. In the case of our specific flow configuration, the enhancement factor reaches 3.2 for the interaction of streptavidin on immobilized biotin (Da=103).The reported simulation results can be compared to an experimental value obtained using the droplet-based surface plasmon resonance sensor streamed in situ using SAW reported by Yeo et al.12 By monitoring the streptavidin∕biotin binding interaction on an activated gold slide, they showed that SAW stirring brings an improvement factor of more than 2. This difference can be accounted to the high complexity of the induced 3D flow, which was modeled in a simple manner in our calculations.Other factors must be taken into account when optimizing the improvement factor, such as the flow velocity and the characteristic length of the mixing. To do so, the Peclet number allows the comparison of the convective and diffusive effects.17 For δC a typical variation in concentration on the distance h, the Peclet number is given by(5)A significantly high Peclet number causes a decrease in biosensing efficiency as the analytes do not have enough time to interact with the biosensing surface by diffusion through the analyte-poor layer. On the contrary, the case of a low Peclet number corresponds to the diffusion-limited problem. Therefore, for each Damköhler number, there is a Peclet number optimizing this factor. To illustrate this fact, Fig. Fig.3b3b shows the calculation of the enhancement factor as a function of the Peclet number for a given Da.In this paper, we showed that surface loading of typical analytes on a droplet-based biosensor can be highly increased by SAW microstirring. The system permits the enhancement of the biosensing performances by the continuous renewal of the analyte-carrying fluid near the sensing surface. Thanks to mean flow speeds measured up to 1800 μm∕s, the SAW microstreaming can be beneficial to the biosensing of a large range of analyte∕ligand interactions. In addition to the biosensing performance improvement, such a method can be easily integrated in micro-micro-total-analysis systems, which makes it a convenient tool for liquid handling in future biochips. 相似文献