scholarly journals Kreowanie doświadczeń liminalnych w szkole z wykorzystaniem metody dramy edukacyjnej

1970 ◽  
pp. 155-176
Author(s):  
Sylwia Jaskulska

The aim of the paper is to consider the possibility of creating liminal experiences at school with the method of educational drama and the pedagogical potential of such activities. Treated as the medium phase of rite, I define liminality in line with Arnold van Genepp and Victor Turner. By claiming that for many reasons school is a liminal space and showing that the fact that this function is neglected at the cost of the transmission function is a problem, I present drama as a possible antidote.

2021 ◽  
pp. 67-73
Author(s):  
Mikhail Bazuev ◽  
◽  
Vitaly Koksharov ◽  
Alexey Naichuk ◽  
◽  
...  

In this work, the analysis of real deviations from the nominal dimensions links, and their cumulative effect on the final movement of the chain linkage element rolling semiautomatic mechanism. The considered mechanism was converted to an equivalent one, consisting of lower translational and rotational kinematic pairs. In the course of the structural analysis, the mechanism was divided into Assur groups in order to simplify further kinematic calculations. The calculation was carried out sequentially for each of the structural groups separately. Based on this, a mathematical model of the kinematics of a rolling semiautomatic mechanism was developed, taking into account the real size of the links, that is, possible deviations of the links size from the nominal values for any combination of them. Using a specific example with the given installation dimensions of the mechanism, the transfer function of the output link (wedge) is built, and the range of its possible change is determined according to the specified dimensional tolerances. Combinations of link sizes for the boundaries of the range of change of the transfer function have been determined It is shown that with the tolerances indicated in accordance with the Unified system of tolerances and fits, the deviation of the position of the output link at the extreme position of the input link (pusher) can reach ±10 of that calculated by the nominal dimensions. This model can be used to solve the problems of optimal selection of tolerances and reduce the cost of manufacturing a product, based on the kinematic restrictions imposed on the functionality of the mechanism. The proposed approach to the construction and analysis of analytical mathematical models can be relevant for a wide variety of industries: machine tool building, engine building, weapons industry and aircraft building, especially where mechanisms are used that form long kinematic chains.


Author(s):  
Douglas L. Dorset ◽  
Barbara Moss

A number of computing systems devoted to the averaging of electron images of two-dimensional macromolecular crystalline arrays have facilitated the visualization of negatively-stained biological structures. Either by simulation of optical filtering techniques or, in more refined treatments, by cross-correlation averaging, an idealized representation of the repeating asymmetric structure unit is constructed, eliminating image distortions due to radiation damage, stain irregularities and, in the latter approach, imperfections and distortions in the unit cell repeat. In these analyses it is generally assumed that the electron scattering from the thin negativelystained object is well-approximated by a phase object model. Even when absorption effects are considered (i.e. “amplitude contrast“), the expansion of the transmission function, q(x,y)=exp (iσɸ (x,y)), does not exceed the first (kinematical) term. Furthermore, in reconstruction of electron images, kinematical phases are applied to diffraction amplitudes and obey the constraints of the plane group symmetry.


Author(s):  
James F. Mancuso

IBM PC compatible computers are widely used in microscopy for applications ranging from control to image acquisition and analysis. The choice of IBM-PC based systems over competing computer platforms can be based on technical merit alone or on a number of factors relating to economics, availability of peripherals, management dictum, or simple personal preference.IBM-PC got a strong “head start” by first dominating clerical, document processing and financial applications. The use of these computers spilled into the laboratory where the DOS based IBM-PC replaced mini-computers. Compared to minicomputer, the PC provided a more for cost-effective platform for applications in numerical analysis, engineering and design, instrument control, image acquisition and image processing. In addition, the sitewide use of a common PC platform could reduce the cost of training and support services relative to cases where many different computer platforms were used. This could be especially true for the microscopists who must use computers in both the laboratory and the office.


Author(s):  
J T Fourie

The attempts at improvement of electron optical systems to date, have largely been directed towards the design aspect of magnetic lenses and towards the establishment of ideal lens combinations. In the present work the emphasis has been placed on the utilization of a unique three-dimensional crystal objective aperture within a standard electron optical system with the aim to reduce the spherical aberration without introducing diffraction effects. A brief summary of this work together with a description of results obtained recently, will be given.The concept of utilizing a crystal as aperture in an electron optical system was introduced by Fourie who employed a {111} crystal foil as a collector aperture, by mounting the sample directly on top of the foil and in intimate contact with the foil. In the present work the sample was mounted on the bottom of the foil so that the crystal would function as an objective or probe forming aperture. The transmission function of such a crystal aperture depends on the thickness, t, and the orientation of the foil. The expression for calculating the transmission function was derived by Hashimoto, Howie and Whelan on the basis of the electron equivalent of the Borrmann anomalous absorption effect in crystals. In Fig. 1 the functions for a g220 diffraction vector and t = 0.53 and 1.0 μm are shown. Here n= Θ‒ΘB, where Θ is the angle between the incident ray and the (hkl) planes, and ΘB is the Bragg angle.


Author(s):  
H. Rose

The imaging performance of the light optical lens systems has reached such a degree of perfection that nowadays numerical apertures of about 1 can be utilized. Compared to this state of development the objective lenses of electron microscopes are rather poor allowing at most usable apertures somewhat smaller than 10-2 . This severe shortcoming is due to the unavoidable axial chromatic and spherical aberration of rotationally symmetric electron lenses employed so far in all electron microscopes.The resolution of such electron microscopes can only be improved by increasing the accelerating voltage which shortens the electron wave length. Unfortunately, this procedure is rather ineffective because the achievable gain in resolution is only proportional to λ1/4 for a fixed magnetic field strength determined by the magnetic saturation of the pole pieces. Moreover, increasing the acceleration voltage results in deleterious knock-on processes and in extreme difficulties to stabilize the high voltage. Last not least the cost increase exponentially with voltage.


Author(s):  
Kazuo Ishizuka

It is well known that taking into account spacial and temporal coherency of illumination as well as the wave aberration is important to interpret an image of a high-resolution electron microscope (HREM). This occues, because coherency of incident electrons restricts transmission of image information. Due to its large spherical and chromatic aberrations, the electron microscope requires higher coherency than the optical microscope. On an application of HREM for a strong scattering object, we have to estimate the contribution of the interference between the diffracted waves on an image formation. The contribution of each pair of diffracted waves may be properly represented by the transmission cross coefficients (TCC) between these waves. In this report, we will show an improved form of the TCC including second order derivatives, and compare it with the first order TCC.In the electron microscope the specimen is illuminated by quasi monochromatic electrons having a small range of illumination directions. Thus, the image intensity for each energy and each incident direction should be summed to give an intensity to be observed. However, this is a time consuming process, if the ranges of incident energy and/or illumination direction are large. To avoid this difficulty, we can use the TCC by assuming that a transmission function of the specimen does not depend on the incident beam direction. This is not always true, because dynamical scattering is important owing to strong interactions of electrons with the specimen. However, in the case of HREM, both the specimen thickness and the illumination angle should be small. Therefore we may neglect the dependency of the transmission function on the incident beam direction.


1994 ◽  
Vol 58 (11) ◽  
pp. 832-835 ◽  
Author(s):  
ES Solomon ◽  
TK Hasegawa ◽  
JD Shulman ◽  
PO Walker
Keyword(s):  

1998 ◽  
Vol 138 (2) ◽  
pp. 205-205
Author(s):  
Snellman ◽  
Maljanen ◽  
Aromaa ◽  
Reunanen ◽  
Jyrkinen‐Pakkasvirta ◽  
...  
Keyword(s):  

2004 ◽  
Vol 171 (4S) ◽  
pp. 40-40
Author(s):  
Leslee L. Subak ◽  
Stephen K. Van Den Eeden ◽  
Jeanette S. Brown ◽  
Arona I. Ragins ◽  
Eric Vittinghoff ◽  
...  

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