Novel on-demand droplet generation for selective fluid sample extraction

A novel microfluidic device enabling selective generation of droplets and encapsulation of targets is presented. Unlike conventional methods, the presented mechanism generates droplets with unique selectivity by utilizing a K-junction design. The K-junction is a modified version of the classic T-junction with an added leg that serves as the exit channel for waste. The dispersed phase fluid enters from one diagonal of the K and exits the other diagonal while the continuous phase travels in the straight leg of the K. The intersection forms an interface that allows the dispersed phase to be controllably injected through actuation of an elastomer membrane located above the inlet channel near the interface. We have characterized two critical components in controlling the droplet size-membrane actuation pressure and timing as well as identified the region of fluid in which the droplet will be formed. This scheme will have applications in fluid sampling processes and selective encapsulation of materials. Selective encapsulation of a single cell from the dispersed phase fluid is demonstrated as an example of functionality of this design.     

The Fourfold Gap: preparing teachers for educating the culturally different

In many countries teachers belonging to the dominant group, either by descent or through enculturation, confront children and youth whose ethnic, cultural, religious or social background is partly or totally different. To teach teachers to deal effectively with the problems caused by these differences, it is proposed to make use of the model of a ‘Fourfold Gap’ between the teacher and the student who belongs to another community: linguistic, cognitive, cultural and social. Within the framework of this model, concrete examples should be used, of the type usually encountered in the daily work of a teacher. A sample of these, taken from Israeli schools, is presented. Measures should be taken to counteract possible negative effects of this method: the emphasis on differences, neglecting similarities; and apprehensions about this ability to deal with situations which seem to require a very high level of knowledge. Use of the model in teacher training and inservice education in Israel has shown its potential for improving teaching in multicultural classrooms.     

The development of an observational instrument for science teaching

Desirable pupil behavior change may come from structured classroom activity. Adapt this observational instrument to some action research need.     

Neuromuscular control mechanisms and strategy in arm movements of attempted supranormal speed

Rapid, goal-directed elbow flexion movements were examined under interacting conditions of inertial loading and resistance to movement initiation. The resistance ceased when movement began, resulting in quick release movements. Inertial load slowed the movement and lengthened the agonist and antagonist electromyographic (EMG) burst durations. The quick release resulted in larger accelerations but only minimal changes in peak velocity. Most aspects of the triphasic EMG pattern were little affected by the quick release, but the build up of agonist EMG and the corresponding rate of static force development differed markedly between load and quick release conditions. These and other data suggest that the specific pattern of agonist muscle activation is set according to neuromuscular constraints of the antagonist muscle and the expectation of movement dynamics.