DNA-library assembly programmed by on-demand nano-liter droplets from a custom microfluidic chip     

Uwe Tangen  Gabriel Antonio S. Minero  Abhishek Sharma  Patrick F. Wagler  Rafael Cohen  Ofir Raz  Tzipy Marx  Tuval Ben-Yehezkel  John S. McCaskill 《Biomicrofluidics》2015,9(4)

Nanoscale synthetic biology can benefit from programmable nanoliter-scale processing of DNA in microfluidic chips if they are interfaced effectively to biochemical arrays such as microwell plates. Whereas active microvalve chips require complex fabrication and operation, we show here how a passive and readily fabricated microchip can be employed for customizable nanoliter scale pipetting and reaction control involving DNA. This recently developed passive microfluidic device, supporting nanoliter scale combinatorial droplet generation and mixing, is here used to generate a DNA test library with one member per droplet exported to addressed locations on microwell plates. Standard DNA assembly techniques, such as Gibson assembly, compatible with isothermal on-chip operation, are employed and checked using off-chip PCR and assembly PCR. The control of output droplet sequences and mixing performance was verified using dyes and fluorescently labeled DNA solutions, both on-chip and in external capillary channels. Gel electrophoresis of products and DNA sequencing were employed to further verify controlled combination and functional enzymatic assembly. The scalability of the results to larger DNA libraries is also addressed by combinatorial input expansion using sequential injection plugs from a multiwell plate. Hence, the paper establishes a proof of principle of the production of functional combinatorial mixtures at the nanoliter scale for one sequence per well DNA libraries.  相似文献   

On demand nanoliter-scale microfluidic droplet generation,injection, and mixing using a passive microfluidic device     

Uwe Tangen  Abhishek Sharma  Patrick Wagler  John S. McCaskill 《Biomicrofluidics》2015,9(1)

We here present and characterize a programmable nanoliter scale droplet-on-demand device that can be used separately or readily integrated into low cost single layer rapid prototyping microfluidic systems for a wide range of user applications. The passive microfluidic device allows external (off-the-shelf) electronically controlled pinch valves to program the delivery of nanoliter scale aqueous droplets from up to 9 different inputs to a central outlet channel. The inputs can be either continuous aqueous fluid streams or microliter scale aqueous plugs embedded in a carrier fluid, in which case the number of effective input solutions that can be employed in an experiment is no longer strongly constrained (100 s–1000 s). Both nanoliter droplet sequencing output and nanoliter-scale droplet mixing are reported with this device. Optimization of the geometry and pressure relationships in the device was achieved in several hardware iterations with the support of open source microfluidic simulation software and equivalent circuit models. The requisite modular control of pressure relationships within the device is accomplished using hydrodynamic barriers and matched resistance channels with three different channel heights, custom parallel reversible microfluidic I/O connections, low dead-volume pinch valves, and a simply adjustable array of external screw valves. Programmable sequences of droplet mixes or chains of droplets can be achieved with the device at low Hz frequencies, limited by device elasticity, and could be further enhanced by valve integration. The chip has already found use in the characterization of droplet bunching during export and the synthesis of a DNA library.  相似文献   

Impacts of government incentives towards industrial innovation: An analysis of the federal programme funding R&D personnel in the Federal Republic of Germany     

Frieder Meyer-Krahmer  Gisela Gilelow  Uwe Kuntze 《Research Policy》1983,12(3):153-169

Against a background of deteriorating national and international economic conditions, increasing importance is being attached by political administrations to the innovative capacities of small and medium-sized firms with respect to the employment situation and to international competitiveness. Consequently, government support of research, development and innovation in these companies has taken a marked upward turn since the late seventies, both in the Federal Republic of Germany and in other industrialized Western countries.The actual impacts of some of these programmes are at present under study by the Fraunhofer-Institut für Systemtechnik und Innovationsforschung (ISI). This paper is an outline of the results of a study of the largest current programme funding R&D and innovation in small and medium-sized firms by offering grants towards the costs of R&D personnel. The impact analysis is being conducted in two rounds: the first round of studies, which is the subject of this report, took place in 1980/1981 and was designed to examine the discernible short-term effects and characteristics of the programme. The second round is planned for 1983/1984 as a summary of the impacts of the programme over the first five years of its term of effect.The subjects of investigation are the quantitative and qualitative changes in R&D activities caused by the programme in the firms under study and the contribution the programme can make to strengthen innovative and competitive capabilities. The conditions underlying the programme are reviewed critically, especially in order to see whether the barriers to innovation and the weak spots assumed did in fact exist in the firms examined. The administrative management, “free rider”-effects, and factors restricting impacts are investigated along with such questions as whether firms located in peripheral regions were reached by the programme to the same extent as firms in conurbation areas. Furthermore, the reasons for non-participation of firms are analyzed.The example of the federal programme funding R&D personnel thus is used in this impact analysis in an attempt to provide empirical data on the significance, the range, and the limits of such a government instrument promoting R&D and innovation in small and medium-sized firms.  相似文献   

Raising the standards by standardization?     

Gellert  Uwe 《Journal of Mathematics Teacher Education》2021,24(5):427-430

Journal of Mathematics Teacher Education -  相似文献   

Centre of mass kinematics of fast bowling in cricket     

Ferdinands R  Marshall RN  Kersting U 《Sports biomechanics / International Society of Biomechanics in Sports》2010,9(3):139-152

Kinematic studies have shown that fast bowlers have run-up velocities, based on centre of mass velocity calculations, which are comparable to elite javelin throwers. In this study, 34 fast bowlers (22.3 +/- 3.7 years) of premier grade level and above were tested using a three-dimensional (3-D) motion analysis system (240 Hz). Bowlers were divided into four speed groups: slow-medium, medium, medium-fast, and fast. The mean centre of mass velocity at back foot contact (run-up speed) was 5.3 +/- 0.6 m/s. Centre of mass velocity at back foot contact was significantly faster in the fastest two bowling groups compared to the slow-medium bowling group. In addition, stepwise multiple regression analysis showed that the centre of mass deceleration over the delivery stride phase was the strongest predictor of ball speed in the faster bowling groups. In conclusion, centre of mass kinematics are an important determinant of ball speed generation in fast bowlers. In particular, bowlers able to coordinate their bowling action with periods of centre of mass deceleration may be more likely to generate high ball speed.  相似文献   

An evaluation of biomechanical measures of bowling action legality in cricket   总被引：1，自引：0，他引：1  

Ferdinands RE  Kersting UG 《Sports biomechanics / International Society of Biomechanics in Sports》2007,6(3):315-333

Cricket bowling is traditionally thought to be a rigid-arm motion, allowing no elbow straightening during the delivery phase. Conversely, research has shown that a perfectly rigid arm through delivery is practically unattainable, which has led to rule changes over the past years. The current rule requires a bowler not to increase the elbow angle by more than 15 degrees, thus requiring a measurement to confirm legality in "suspect" bowlers. The aims of this study were to evaluate whether the current rule is maintained over a range of bowlers and bowling styles, and to ascertain whether other kinematics measures may better differentiate between legal and suspect bowling actions. Eighty-three bowlers of varying pace were analysed using reflective markers and a high-speed (240 Hz) eight-camera motion analysis system in a laboratory. The change in elbow segment angle (minimum angle between the arm and forearm), the change in elbow extension angle with respect to the flexion-extension axis of a joint coordinate system, and the elbow extension angular velocity at ball release were measured. We found that bowlers generally bowled within a change in elbow extension angle of 15.5 degrees. However, this limit was unable to differentiate groups of bowlers from those who were suspected of throwing in the past. Improved differentiation was attained using the elbow extension angular velocity at ball release. The elbow extension angular velocity at ball release may be conceptually more valid than the elbow extension angle in determining which bowlers use the velocity-contributing mechanisms of a throw. Also, a high value of elbow extension angular velocity at ball release may be related to the visual impression of throwing. Therefore, it is recommended that researchers and cricket legislators examine the feasibility of specifying a limit to the elbow extension angular velocity at ball release to determine bowling legality.  相似文献   

Global Mistrust in News: The Impact of Social Media on Trust     

Sora Park  Caroline Fisher  Terry Flew  Uwe Dulleck 《媒体管理杂志》2020,22(2):83-96

ABSTRACT

Digital platforms such as search engines and social media have become major gateways to news. Algorithms are used to deliver news that is consistent with consumers’ preferences and individuals share news through their online social networks. This networked environment has resulted in growing uncertainty about online information which has had an impact on news industries globally. While it is well established that perceptions of trust in news found on social media or via search engines are lower than traditional news media, there has been less discussion about the impact of social media use on perceptions of trust in the news media more broadly. This study fills that gap by examining the influence of social media as news sources and pathways to news on perceptions of the level of news trust at a country level. A secondary data analysis of a 26-country survey in 2016 and 2019 was conducted. The analysis revealed an increase in social media use for accessing news resulted in a decline in trust in news media generally across the globe. Higher levels of general mistrust in news were related to an increased use of sharing of news. This paper argues the use of social media for news is closely linked to the increase in news mistrust, which is likely to continue to rise as the number of people using social media to access news continues to grow.  相似文献   

Effects of Transactional and Transformational Governance on Academic Teaching: Empirical evidence from two types of higher education institutions     

Wilkesmann  Uwe 《Tertiary Education and Management》2013,19(4):281-294

The article considers the importance of examining how members of university governing bodies understand and perform their roles in the politically complex context of contemporary higher education. While a growing body of scholarly literature is devoted to the study of university governance, much of this work neglects the human aspects of decision‐making in the presence of the competing interests, societal expectations and government intervention currently besetting universities. This article argues that, given this context, understanding of the factors impacting on university governing body effectiveness will be greatly enhanced by interpretive analysis of qualitative data obtained from university governance practitioners themselves.  相似文献   

Towards a Bernsteinian language of description for mathematics classroom discourse     

Hauke Straehler-Pohl  Uwe Gellert 《British Journal of Sociology of Education》2013,34(3):313-332

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Constructive readings of interactive episodes: examining ethics in physical education from a social constructionist perspective     

Dean M. Barker  Natalie Barker-Ruchti  Uwe Pühse 《Sport, Education and Society》2013,18(4):511-526

In this paper we illustrate how ways of thinking about ethics are tied up with sport and physical education practice and introduce an alternative approach that can help to develop ethical pedagogies. We begin by locating socio-moral education in physical education within historical and contemporary pedagogical scholarship. Our argument is that the work of today's physical educators is still shaped by claims that were made about school sport in the nineteenth century and that sport scholars have long had difficulties proving these claims empirically. Rather than search for data that can confirm or refute claims of moral learning, we examine how incidents related to moral behaviour occur during physical education lessons. To do this we draw on data from an ethnographic investigation of a school in North Western Switzerland. Specifically, we present three episodes of interaction in three different physical education lessons. To make sense of these episodes, we introduce a social constructionist perspective. The main assumptions of this perspective are: (1) meanings are created through dialogue and consensus and are context-relative; (2) interactions between people are joint accomplishments; and (3) contexts affect how people interact with one another. Equipped with a constructionist framework, we then inspect the interactive episodes more closely. We include brief discussions of how constructionist understandings might inform ethics pedagogies in the future, suggesting that practitioners should be cautious of universal understandings of ethics, consider pupils as members of communities that are held together by shared practices, provide space for pupils to position themselves differently during lessons and, finally, account for contextual factors when evaluating pupils’ actions.  相似文献