Proximity development

Consequently we have selected three tasks in three relevant domains of chemistry and (material or food) technology which are expected to be within the zone of proximal development for students ... 

Educational constructivism extended the realism-empiricism dichotomy into how individuals learn, and assumed two main forms (19) (i) personal constructivism, which is associated with Piaget (5) and (ii) social-cultural constructivism which is linked to Vygotsky. Piagetian constructivism is associated with an idealized person (the epistemic subject ). On die other hand, according to Vygotsky (20), the learner constructs actively his/her knowledge, but this process is greatly assisted by interactions with peers and with the teacher who acts at the students zone of proximal development. 

To respond to such calls Sileshi and Barke - after reviewing the major chemistry education concepts - proposed the Tetrahedral-ZPD metaphor. This metaphor re-hybridizes the very powerful 3D-tetrahedral chemistry education concept proposed by Mahaffy [22] macroscopic, molecular, representational, and human element. With the idea of the Zone of Proximal Development (ZPD) of social constructivist Vygotsky [23], ZPD should describe the distance between the actual development level as determined by independent problem solving and the level of potential development as determined through problem solving under adult guidance or in collaboration with more capable peers [23],... 

Figure 22.5 Urodele fore limb development analysed by 3B3 immunostaining for chondroitin-6-S04 of Salamandrella (I) and axolotl (2). Differences in developmental timing are clear in Salamandrella carpus differentiation is proximodistal but in the axolotl be is in advance of the intermedium (i) indicating distal to proximal development. Note in both the digital arch, da . (A=anterior P=posterior). From Hinchliffe and Vorobyeva (1999).

Central to all SPMs (or local probe methods , or local proximal probes as they are sometimes called) is the presence of a tip or sensor, typically of less than 100 mn radius, that is rastered in close proximity to—or in contact with—tire sample s surface. This set-up enables a particular physical property to be measured and imaged over the scaimed area. Crucial to the development of this family of teclmiques were both the ready availability of piezoelements, with which the probe can be rastered with subnanometre precision, and the highly developed computers and stable electronics of the 1980s, without which the operation of SPMs as we know them would not have been possible. 

L First manufacturing use of chemically amplified resists Plasma-developed resist first described X-ray proximity lithography demonstrated Bis-azide rubber resists introduced DNO-novolac resist for microelectronics introduced Photoresist technology first applied to transistor fabrication DNO-novolac resist patented by Kalle... 

A number of methods have been developed to introduce context to on-line databases, enabling searches to be refined to minimized false retrieval. One of the earliest techniques is proximity searching, in which two words are required to be adjacent, or within a limited distance from each other in text. The assignment of roles to chemical substances is a method of precoordinating concepts. A substance can be identified as a reactant, as a product, and in some systems in a number of additional roles. For example, by searching for documents in which formaldehyde is a product, documents in which it is a reactant, or in which it undergoes no reaction, are thus eliminated. 

Isocyanates. Isocyanates in general are toxic chemicals and require great care in handling. Oral ingestion of substantial quantities of isocyanates can be tolerated by the human body, but acute symptoms may develop from the inhalation of much smaller amounts. The inhalation of isocyanates presents a ha2ard for the people who work with them as weU as the people who Hve in the proximity of an isocyanate plant. Adequate control of exposure is necessary to achieve a safe working environment. The suppHers Material Safety Data Sheets (MSDS) have to be consulted for the most current information on the safe handling of isocyanates. 

Calendering can achieve surprising accuracy on the thickness of a sheet. Typically the tolerance is 0.005 mm but to achieve this it is essential to have very close control over roll temperatures, speeds and proximity. In addition, the dimensions of the rolls must be very precise. The production of the rolls is akin to the manufacture of an injection moulding tool in the sense that very high machining skills are required. The particular features of a calender roll are a uniform specified surface finish, minimal eccentricity and a special barrel profile ( crown ) to compensate for roll deflection under the very high presurres developed between the rolls. 

Does eaeh worksite require a separate HASP, or ean one plan eover multiple worksites In general, eaeh HASP should address only one worksite. However, this is not a requirement. A situation eould arise in whieh it is deeided to use one HASP for multiple worksites. We believe that the approaeh used should depend on eonditions at the worksite. If worksites are similar, in near proximity to eaeh other, and aetivities are phased together, one HASP may be preferred. If worksites have enough diflferenees that need to be addressed in the HASP and these differenees eould eause eonfusion in the field, then more than one HASP should be developed. 

The influence of room transverse cross-section configuration on airflow patterns created by air jets supplied through round nozzles in proximity to the ceiling was studied by Baharev and Troyanovsky and Nielsen (see Fig. 7.37). Based on experimental data, they concluded that when the room width B is less than 3.5H, the jet attaches to the ceiling and spreads, filling the whole width of the room in the manner of a linear jet. The reverse flow develops under the jet. When B > 4H, the reverse flow also develops along the jet sides. Baharev and Troyanovsky indicated that air temperature and velocity distribution in the occupied zone is more uniform when the jet develops in the upper zone and the occupied zone is ventilated by the reverse flow. Thus, they proposed limiting room width to 3-3.5H,. 

Pew et al. (1981), developed a series of "Murphy diagrams" (named after the well-known Murphy s Law If something can go wrong, it will). Each decision element in the Rasmussen model has an associated Murphy diagram, which specifies possible direct "proximal") causes of the internal malfunction. Each of these causes are then considered in terms of indirect "distal") causes which could mfluence or give rise to the primary cause. A Murphy diagram for the... 

The landmark report by Winstein et al. (Scheme 3.6) on the powerful accelerating and directing effect of a proximal hydroxyl group would become one of the most critical in the development of the Simmons-Smith cyclopropanation reactions [11]. A clear syw directing effect is observed, implying coordination of the reagent to the alcohol before methylene transfer. This characteristic served as the basis of subsequent developments for stereocontrolled reactions with many classes of chiral allylic cycloalkenols and indirectly for chiral auxiliaries and catalysts. A full understanding of this phenomenon would not only be informative, but it would have practical applications in the rationalization of asymmetric catalytic reactions. 

---