Families of asymptotic tensile crack tip stress fields in elastic-perfectly plastic single crystals

In this work, two families of asymptotic near-tip stress fields are constructed in an elastic-ideally plastic FCC single crystal under mode I plane strain conditions. A crack is taken to lie on the (010) plane and its front is aligned along the [(1) over bar 01] direction. Finite element analysis is first used to systematically examine the stress distributions corresponding to different constraint levels. The general framework developed by Rice (Mech Mater 6:317-335, 1987) and Drugan (J Mech Phys Solids 49:2155-2176, 2001) is then adopted to generate low triaxiality solutions by introducing an elastic sector near the crack tip. The two families of stress fields are parameterized by the normalized opening stress (tau(A)(22)/tau(o)) prevailing in the plastic sector in front of the tip and by the coordinates of a point where elastic unloading commences in stress space. It is found that the angular stress variations obtained from the analytical solutions show good agreement with finite element analysis.

Surface waves in the presence of external high frequency fields

The system equations of a collisionless, unmagnetized plasma, contained in a box where a high frequency (HF) electric field is incident, are solved in the electrostatic approximation. The surface modes of the plasma in the semi-infinite and box geometry are investigated. In thi high frequency limit, the mode frequencies are not significantly changed by the HF field but their group velocities can be quite different. Two long wavelength low frequency modes, which are not excited in the absence of HF field, are found. These modes are true surface modes (decaying on one wavelength from the surface) unlike the only low frequency ion acoustic mode in the zero field case. In the short wavelength limit the low frequency mode occurs at omega i/ square root 2, omega i being the ion plasma frequency, as a result similar to the case of no HF field.

Helmholtz Instability In Stratified Shear Flows With Magnetic-Fields

The stability characteristics of a Helmholtz velocity profile in a stratified Boussinesq fluid in the presence of a rigid boundary is studied, A jump in the magnetic field is introduced at a level different from the velocity discontinuity. New unstable modes in addition to the Kelvin-Helmhottz mode are found. The wavelengths of these unstable modes are close to the wavelengths of internal Alfv6n gravity waves in the atmospher.

Untersuchungen zur Fachsprache der Ökologie und des Umweltschutzes im Deutschen und Finnischen : Bezeichnungsvarianten unter einem geschichtlichen, lexikographischen, morphologischen und linguistisch-pragmatischen Aspekt

The work integrates research in the language and terminology of various fields with lexicography, etymology, semantics, word formation, and pragmatics. Additionally, examination of German and Finnish provides the work with perspective of contrastive linguistics and the translation of texts in specialized fields. The work is an attempt to chart the language, vocabulary, different textual types, and essential communication-connected features of this special field. The study is primary concerned with internal communication within the field of ecology, but it also provides a comparison of the public discussion of environmental issues in Germany and Finland. The work attempts to use textual signs to provide a picture of the literary communication used on the different vertical levels in the central text types within the field. The dictionaries in the fields of environmental issues and ecology for the individual text types are examined primarily from the perspective of their quantity and diversity. One central point of the work is to clarify and collect all of the dictionaries in the field that have been compiled thus far in which German and/or Finnish ware included. Ecology and environmental protection are closely linked not only to each other but also to many other scientific fields. Consequently, the language of the environmental field has acquired an abundance of influences and vocabulary from the language of the special fields close to it as well as from that of politics and various areas of public administration. The work also demonstrates how the popularization of environmental terminology often leads to semantic distortion. Traditionally, scientific texts have used the smallest number of expressions, the purpose of which is to appeal to or influence the behavior of the text recipient. Particularly in Germany, those who support or oppose measures to protect the environment have long been making concerted efforts to represent their own views in the language that they use. When discussing controversial issues competing designations for the same referent or concept are used in accordance with the interest group to which the speaker belongs. One of the objectives of the study is to sensitize recipients of texts to notice the euphemistic expressions that occur in German and Finnish texts dealing with issues that are sensitive from the standpoint of environmental policy. One particular feature of the field is the wealth and large number of variants designating the same entry or concept. The terminological doublets formed by words of foreign origin and their German or Finnish language equivalents are quite typical of the field. Methods of corpus linguistics are used to determine the reasons for the large number of variant designations as well as their functionality.

Formative time lags in nitrogen, oxygen and dry air In crossed electric and magnetic fields

Formative time lags in nitrogen, oxygen, and dry air are measured with and without a magnetic field over a range of gas pressures (0.05 ' p ' 20.2 torr 5 kPa to 2 MPa, electric field strengths (1.8xO14 EEs 60xlO V m l) and magnetic field strengths (85xl0-4 < B ' 16x10-2 Tesla). For experiments below the Paschen minimum, the electrodes are designed to ensure that breakdown occurs over longer gaps and for experiments above the Paschen minimum, a coaxial cylindrical system is employed. The experimental technique consists of applying pulse voltages to the gap at various constant values of E/p and B/p and measuring the time lags from which the formative time lags are separated. In the gases studed, formative time lags decrease on application of a magnetic field at a given pressure for conditions below the Paschen minimum. The voltages at which the formative time lags remain the same without and with magnetic fields are determined, and electron molecule collision frequencies (v/p) are determined using the Effective Reduced Electric Field [EREF] concept. With increasing ratio of E/p in crossed fields, v/p decreases in all the three gases. Measurements above the Paschen minimum yield formative time lags which increase on application of a magnetic field. Formative time lags in nitrogen in ExB fields are calculated assuming an average collision frequency of 8.5x109 sec-1 torr 1. It is concluded that the EREF concept can be applied to explain formative time lags in ExB fields.

Kansanomainen moraali : Tutkimus savolaisista ja pohjalaisista uskomustarinoista

In my research I discuss belief legends as representations of folk morals. Doing wrong is not one s private affair because it can have consequences for the life of a whole community, and therefore, it is in a community s interest to control the conduct of its members. Belief legends have served as a means of instruction for proper behaviour. In this way a community has contributed to the socialization of its members so as to make them comply with common norms and morals. My study is focused on belief legends relating to some type of offence (a crime, an infringement or another kind of misdeed) and its consequences. I try to find out whether there are regional differences and similarities. The material consists of 3120 warning legends that have been recorded in the years 1881‒1981, mainly in Southern Savo and Southern Ostrobothnia, partly in Northern Savo and Northern Ostrobothnia. I have collected the material at the Folklore Archives of the Finnish Literature Society. As a research method I apply discourse analysis to outline the schematic model of the legends, the superstructure, and the substance of the legends, the semantic macrostructure. Also I apply quantitative methods such as cross tabulations in order to establish regional differences and similarities in the concentrated and far abstracted semantic macrostructure of the legends. I look for explanations for the perceptions made in, above all, the cultural context but also with the view of the development of judicial history. Warning legends relating to what is wrong or right are clearly an expression of peasant folklore. The most common types of offences are violations of law and transgressions of Christian traditions and of social conduct. Transgression of Christian traditions is the most frequently committed offence in all geographical areas surveyed. Warning legends have an explicit focus on offence committed by a single person. The most common punishing figure in Southern Savo is the Devil, in Southern Ostrobothnia the Dead, in Northern Savo God, and in Northern Ostrobothnia the Dead or God. The most rigid folk morals are manifested in legends from Northern Savo, where narratives of mortal sin are more frequent than in other areas. The influence of the revivalist movements may be alleged in explanation of this phenomenon. According to these legends people living in Southern Savo are the most tolerant of those included in the study, presumably because of a more liberal revivalist movement in this area, called the Friendship movement. In folk morals women are treated more severely than men. Characteristic of the legends from Ostrobothnia is the emphasis on community, while the legends from Savo lay stress on individuality. The legends from Ostrobothnia manifest a more explicit distinction between the offence committed by a woman and one committed by a man than do legends from Savo. An explanation may be found in the prevailing industries, adherent in the division of labour between the sexes, in this region. The legends are man-centric. Women s occupations are connected with home and family, whereas men s fields of activities are wider. Women moralise each other harsher than do men. Folk morals advise people to be moderate in every sense. Through belief legends people are taught to respect human beings and the rest of creation, to obey the Christian religion and God, and to be moderate in search of wealth.

Reasoning about natural language phrases for semantic goal driven exploration

This paper presents a symbolic navigation system that uses spatial language descriptions to inform goal-directed exploration in unfamiliar office environments. An abstract map is created from a collection of natural language phrases describing the spatial layout of the environment. The spatial representation in the abstract map is controlled by a constraint based interpretation of each natural language phrase. In goal-directed exploration of an unseen office environment, the robot links the information in the abstract map to observed symbolic information and its grounded world representation. This paper demonstrates the ability of the system, in both simulated and real-world trials, to efficiently find target rooms in environments that it has never been to previously. In three unexplored environments, it is shown that on average the system travels only 8.42% further than the optimal path when using only natural language phrases to complete navigation tasks.

The Networks of Learning in Technological Innovation : The Emergence of Collaboration Across Fields of Expertise

This study addresses four issues concerning technological product innovations. First, the nature of the very early phases or "embryonic stages" of technological innovation is addressed. Second, this study analyzes why and by what means people initiate innovation processes outside the technological community and the field of expertise of the established industry. In other words, this study addresses the initiation of innovation that occurs without the expertise of established organizations, such as technology firms, professional societies and research institutes operating in the technological field under consideration. Third, the significance of interorganizational learning processes for technological innovation is dealt with. Fourth, this consideration is supplemented by considering how network collaboration and learning change when formalized product development work and the commercialization of innovation advance. These issues are addressed through the empirical analysis of the following three product innovations: Benecol margarine, the Nordic Mobile Telephone system (NMT) and the ProWellness Diabetes Management System (PDMS). This study utilizes the theoretical insights of cultural-historical activity theory on the development of human activities and learning. Activity-theoretical conceptualizations are used in the critical assessment and advancement of the concept of networks of learning. This concept was originally proposed by the research group of organizational scientist Walter Powell. A network of learning refers to the interorganizational collaboration that pools resources, ideas and know-how without market-based or hierarchical relations. The concept of an activity system is used in defining the nodes of the networks of learning. Network collaboration and learning are analyzed with regard to the shared object of development work. According to this study, enduring dilemmas and tensions in activity explain the participants' motives for carrying out actions that lead to novel product concepts in the early phases of technological innovation. These actions comprise the initiation of development work outside the relevant fields of expertise and collaboration and learning across fields of expertise in the absence of market-based or hierarchical relations. These networks of learning are fragile and impermanent. This study suggests that the significance of networks of learning across fields of expertise becomes more and more crucial for innovation activities.

Semantic Fluency in Mild and Moderate Alzheimer's Disease

Alzheimer's disease (AD) is characterized by an impairment of the semantic memory responsible for processing meaning-related knowledge. This study was aimed at examining how Finnish-speaking healthy elderly subjects (n = 30) and mildly (n=20) and moderately (n = 20) demented AD patients utilize semantic knowledge to performa semantic fluency task, a method of studying semantic memory. In this task subjects are typically given 60 seconds to generate words belonging to the semantic category of animals. Successful task performance requires fast retrieval of subcategory exemplars in clusters (e.g., farm animals: 'cow', 'horse', 'sheep') and switching between subcategories (e.g., pets, water animals, birds, rodents). In this study, thescope of the task was extended to cover various noun and verb categories. The results indicated that, compared with normal controls, both mildly and moderately demented AD patients showed reduced word production, limited clustering and switching, narrowed semantic space, and an increase in errors, particularly perseverations. However, the size of the clusters, the proportion of clustered words, and the frequency and prototypicality of words remained relatively similar across the subject groups. Although the moderately demented patients showed a poor eroverall performance than the mildly demented patients in the individual categories, the error analysis appeared unaffected by the severity of AD. The results indicate a semantically rather coherent performance but less specific, effective, and flexible functioning of the semantic memory in mild and moderate AD patients. The findings are discussed in relation to recent theories of word production and semantic representation. Keywords: semantic fluency, clustering, switching, semantic category, nouns, verbs, Alzheimer's disease

Integrated semantic processing of complex pictures and spoken sentences - Evidence from event-related potentials

It has been suggested that semantic information processing is modularized according to the input form (e.g., visual, verbal, non-verbal sound). A great deal of research has concentrated on detecting a separate verbal module. Also, it has traditionally been assumed in linguistics that the meaning of a single clause is computed before integration to a wider context. Recent research has called these views into question. The present study explored whether it is reasonable to assume separate verbal and nonverbal semantic systems in the light of the evidence from event-related potentials (ERPs). The study also provided information on whether the context influences processing of a single clause before the local meaning is computed. The focus was on an ERP called N400. Its amplitude is assumed to reflect the effort required to integrate an item to the preceding context. For instance, if a word is anomalous in its context, it will elicit a larger N400. N400 has been observed in experiments using both verbal and nonverbal stimuli. Contents of a single sentence were not hypothesized to influence the N400 amplitude. Only the combined contents of the sentence and the picture were hypothesized to influence the N400. The subjects (n = 17) viewed pictures on a computer screen while hearing sentences through headphones. Their task was to judge the congruency of the picture and the sentence. There were four conditions: 1) the picture and the sentence were congruent and sensible, 2) the sentence and the picture were congruent, but the sentence ended anomalously, 3) the picture and the sentence were incongruent but sensible, 4) the picture and the sentence were incongruent and anomalous. Stimuli from the four conditions were presented in a semi-randomized sequence. Their electroencephalography was simultaneously recorded. ERPs were computed for the four conditions. The amplitude of the N400 effect was largest in the incongruent sentence-picture -pairs. The anomalously ending sentences did not elicit a larger N400 than the sensible sentences. The results suggest that there is no separate verbal semantic system, and that the meaning of a single clause is not processed independent of the context.

Note On The Stability Of Parallel Magnetic-Fields - Comment

It is shown that the conclusions arrived at regarding the instability of an incompressible fluid cylinder in the presence of the magnetic field and the streaming velocity in a recent communication easily follow from the study of propagation characteristics of Alfvén surface waves along cylindrical plasma columns made earlier.

Do elasmobranch reactions to magnetic fields in water show promise for bycatch mitigation?

Elasmobranchs are under increasing pressure from targeted fisheries worldwide, but unregulated bycatch is perhaps their greatest threat. This study tested five elasmobranch bycatch species (Sphyrna lewini, Carcharhinus tilstoni, Carcharhinus amblyrhynchos, Rhizoprionodon acutus, Glyphis glyphis) and one targeted teleost species (Lates calcarifer) to determine whether magnetic fields caused a reaction response and/or change in spatial use of an experimental arena. All elasmobranch species reacted to magnets at distances between 0.26 and 0.58 m at magnetic strengths between 25 and 234 gauss and avoided the area around the magnets. Contrastingly, the teleosts showed no reaction response and congregated around the magnets. The different reactions of the teleosts and elasmobranchs are presumably driven by the presence of ampullae of Lorenzini in the elasmobranchs; different reaction distances between elasmobranch species appeared to correlate with their feeding ecology. Elasmobranchs with a higher reliance on the electroreceptive sense to locate prey reacted to the magnets at the greatest distance, except G. glyphis. Notably, this is the only elasmobranch species tested with a fresh- and saltwater phase in their ecology, which may account for the decreased magnetic sensitivity. The application of magnets worldwide to mitigate the bycatch of elasmobranchs appears promising based on these results.