Cathodoluminescence-mode imaging of dislocations in zinc oxide

Abstract

The cathodoluminescence mode in the scanning electron microscope has been used to image bands of dislocations in zinc oxide. It has been shown that dislocations lying on pyramidal, {1012}, planes are generated beneath indentations on {0001} surfaces. Basal plane dislocations lying parallel to the surface are also observed. Indentations on {1100} prismatic surfaces result in slip on {0001} and {0110} planes.     

Holistic processes in the perception and transformation of disoriented figures

Two experiments tested whether mental rotation of complex, hierarchical stimuli occurs holistically or separately at global and local levels of structure. Large (global) letters were constructed from spatial arrangements of small (local) letters. Reflection conditions (normal vs. reflected) were produced by varying the two levels independently. The task was structured so that subjects could rotate one level of the stimulus in some conditions but had to rotate both levels in other conditions. Experiment 1 showed that rotation rate was not affected by the number of levels that had to be rotated to make a reflection decision. This result implies that the rotation of global and local levels occurred together rather than sequentially. Experiment 2 showed that the rotation of the two levels was holistic as opposed to parallel and independent. The results also demonstrate that global information is processed faster than local information regardless of whether or not a rotation is performed. These findings are discussed in relation to theories of mental rotation and global precedence.     

The self in transformation: Dialectical processes in long-term psychotherapy

A number of phases are notable during the process of integration of the self through psychotherapy. Each of these phases encompasses a particular ontology in relation to the dynamic self. The underlying process of change, moreover, may be conceived of as dialectical in nature with each phase having a unique thesis and antithesis. A clinical case is presented to illustrate these ideas for the therapist.     

The ethics of return migration and education: transnational duties in migratory processes

ABSTRACT

This paper argues that most prominent normative theories on immigration neglect a critical dimension of the migratory phenomenon, a neglect that blinds them to important rights that, under some circumstances, immigrants ought to have as a matter of justice. Specifically, the paper argues that these theories fail to appreciate that the children of immigrant families, regardless of whether they were born in their parents’ country or in the host country, should benefit from educational rights addressing needs that are particular to their situation. These children may be forced to move between these two countries. This situation generates an obligation for both states (‘receiving’ and ‘sending’) to act jointly to provide educational opportunities so that these children are fully conversant with both cultures and in both languages. Put succinctly, then, we argue that since children of immigrant families lack any certainty of permanent residence in the host society owing to the threat of deportation and the precarity of their legal status, host and home societies bear the duty to offer an education that allows them to be functional in both societies.     

Whispering gallery mode sensor for phase transformation and solidification studies

Whispering gallery mode (WGM) sensors are created by coupling a dielectric microresonator with the evanescent field of an optical fiber. Since the sensor is created by two separate entities, most of the existing studies are limited to using them in fluid environments, such as air or water, for the ease of manipulation and placement in the optimum configuration. This work is focused on studying the possibility of using WGM sensors inside a solid material. The sensor is immersed in water, which is cooled to solid state and the sensor survival is monitored. In subsequent studies, three remelting cycles are carried out and temperature measurements are obtained through the sensor. The sensor output is calibrated with the temperature data obtained from a thermocouple. The results show that a linear relationship exists between temperature and WGM shift, which enables application of these sensors in temperature measurement. Considering that the sensitivity of WGM sensors is very high (10^?6 N force and 10^?5 K temperature), they can be used for high resolution studies on solidification in cryogenic environments.     

Polarity determination of zinc oxide nanorods by defocused convergent-beam electron diffraction

The crystal polarity of wurtzite zinc oxide nanorods grown hydrothermally parallel to the c?=?[0001] direction has been determined by convergent-beam electron diffraction using a defocused probe. The method enables a simple comparison of the diffracted intensities in ±0002 reflections across side-on nanorods, demonstrating growth in this case is in the c?=?[0001] direction. The method is shown to be viable for nanorods down to about 11?nm in diameter.     

To stay or to return: Rapprochement processes in the migration of adolescents and young adults

The migration of adolescents and young adults is analyzed in terms of the separation-individuation process—an attempt at separation, reflecting conflictual feelings around autonomy and dependency needs. This paper focuses on the acute ambivalence typical of the rapprochement phase of personality development during childhood and applying this to understanding the adolescent and young adult during their migration experiences. The young immigrants to Israel are observed to alternate between physical approaching and then distancing in relation to both the new country (Israel) and the country of origin (the homeland). Four clinical examples of young persons are presented to illustrate the rapprochement process in some immigrants.     

Reversible phase transition in vanadium oxide films sputtered on metal substrates

Vanadium oxide films, deposited on aluminium (Al), titanium (Ti) and tantalum (Ta) metal substrates by pulsed RF magnetron sputtering at a working pressure of 1.5 x10^?2 mbar at room temperature are found to display mixed crystalline vanadium oxide phases viz., VO₂, V₂O₃, V₂O₅. The films have been characterized by field-emission scanning electron microscopy, X-ray diffraction, differential scanning calorimetry (DSC) and X-ray photoelectron spectroscopy, and their thermo-optical and electrical properties have been investigated. Studies of the deposited films by DSC have revealed a reversible-phase transition found in the temperature range of 45–49 °C.     

Deformation strengthening of grain-boundary sliding in a Pb-62wt% Sn alloy

Abstract

Direct observation in a scanning electron microscope of the evolution of the grain-boundary sliding (GBS) process in a Pb-62wt%Sn eutectic alloy during superplastic deformation in shear is reported. The distribution of GBS along the shear surface is found to be inhomogeneous and there is evidence of coupling of the processes of GBS and grain-boundary migration. The rate of GBS increases at small stages of strain (up to about 0·8) and decreases thereafter, indicating that the GBS process is eventually accompanied by strain hardening. The observations are compatible with the dislocation model for GBS.     

Mobile communication and the transformation of daily life: The next phase of research on mobiles

Conclusion In 2004, Prof. Christopher Henshilwood of the University of Bergen discovered in South Africa what appears to be the oldest known jewelry—75,000 year old pierced and ochre-tinted tick shells. His discovery suggested the importance of jewelry and other forms of interpersonal communication and representation. Henshilwood asserts that “once symbolically mediated behavior was adopted by our ancestors it meant communication strategies rapidly shifted, leading to the transmission of individual and widely shared cultural values” (Graham 2004). If we agree with Prof. Henshilwood’s assessment of the import of the initial use of symbolic display technologies (in this case, tick shell decorative jewelry), the implications for evolving practices of mobile communication technology may be even more significant than we generally assume. Specifically, novel forms of widespread mediated communication could alter the cultural values we embrace and transmit. They could also transform social structure, interpersonal processes and land use in ways we might neither anticipate nor desire. The lines of investigation sketched above are important since the illuminate understand current and emerging social practices and their implications. Mobile technology allows unprecedented permutations and concatenation of innovations in communication at the levels of place and space, individual, group and mass, and creative new services offered from a range of entities from amateur creators to gigantic corporations. Therefore, we have an opportunity to structure services and social practices in a self-aware way that should be conductive to outcomes that are better than would otherwise be the case. I would, for the purposes of argument, go further and suggest that it might be the case that the mobile communication is also likely to be a transformative technology. He is the author of Connections: Social and Cultural Studies of the Telephone in American Life (1999) and editor of Machines that Become Us: The Social Context of Personal Communication Technology (2003), both available from Transaction Publishers.     

Optimal control in the critical phase of movement: A functional approach to motor planning processes

Grasping movements are often planned in a way that they end in a position where joints are in an anatomically medial position. This behaviour is termed the “end-state comfort” (ESC) effect (Rosenbaum et al., 1990). We suggest that the anatomically medial position is favoured to control the most difficult part of the movement. In most experiments investigating ESC, objects have to be placed onto a target location, and the highest precision demand occurs at the end of the movement. Thus, ESC is confounded with movement difficulty. In this study, we dissociate movement difficulty and ESC. In our experiments, participants had to execute a task where the critical part of the movement was either at the end or at the beginning of the movement. Participants' grasping behaviour confirmed the hypothesis that movement planning is constrained by a goal for optimal control during the part of the movement that demands the highest precision, rather than by a goal to end in a comfortable state (Rosenbaum, Chapman, Weigelt, Weiss, & van der Wel, 2012). We identified recall and movement plan generating processes of motor planning (Cohen & Rosenbaum, 2004), that ensure the optimal control in the critical part of movement. Our results indicate that recall processes depend on motor experience which is acquired in different time scales. We suggest that motor planning processes are triggered only if the costs for executing movements controlled by recall processes exceed the costs for generating a motor plan.     

Characterization of grain-boundary dislocation networks by a combination of large-angle convergent-beam electron diffraction and weak-beam techniques

The Burgers vector of very close intrinsic dislocations in a near-Σ = 11,{311} grain-boundary in nickel is identified using a geometrical method based on local and accurate measurements of the angular deviation from perfect coincidence Σ = 11 by large-angle convergent-beam electron diffraction and of the dislocation spacing from weak-beam images of the grain boundary.     

Measuring grain-boundary segregation in nanocrystalline alloys: direct validation of statistical techniques using atom probe tomography

Atom probe tomography (APT) is used to investigate grain-boundary segregation of W solute atoms in nanocrystalline Ni. For the heat-treated specimens used here, the grain structure can be observed in the APT data, enabling direct composition analyses across individual grain boundaries. These direct measurements are used to validate methods proposed in earlier work, which determine the average segregation state in nanocrystalline materials through statistical analysis of the solute distribution, without knowledge of the boundary positions. Good agreement is demonstrated between the two experimental techniques.     

Separating perceptual processes from decisional processes in identification and categorization

Four observers completed perceptual matching, identification, and categorization tasks using separable-dimension stimuli. A unified quantitative approach relating perceptual matching, identification, and categorization was proposed and tested. The approach derives from general recognition theory (Ashby & Townsend, 1986) and provides a powerful method for quantifying the separate influences of perceptual processes and decisional processes within and across tasks. Good accounts of the identification data were obtained from an initial perceptual representation derived from perceptual matching. The same perceptual representation provided a good account of the categorization data, except when selective attention to one stimulus dimension was required. Selective attention altered the perceptual representation by decreasing the perceptual variance along the attended dimension. These findings suggest that a complete understanding of identification and categorization performance requires an understanding of perceptual and decisional processes. Implications for other psychological tasks are discussed.     

Dispositional traits and internal migration: Personality as a predictor of migration in Australia

This study analyses a large longitudinal panel dataset (HILDA, or the Household Income and Labour Dynamics in Australia) to assess the extent to which personality traits predict four constructs pertaining to the migration decision: intention to migrate, certainty around intention, migration outcomes, and the strength of association between migration intention and subsequent migration outcomes. Results show small but significant effects of Extraversion and Openness on both migration and intention to migrate. Openness negatively predicted certainty around intention, and Conscientiousness related to the extent to which migration intentions align with outcomes for those who did migrate, while Extraversion predicted migration events among those without a prior intention to migrate.     

Separating perceptual processes from decisional processes in identification and categorization.

Four observers completed perceptual matching, identification, and categorization tasks using separable-dimension stimuli. A unified quantitative approach relating perceptual matching, identification, and categorization was proposed and tested. The approach derives from general recognition theory (Ashby & Townsend, 1986) and provides a powerful method for quantifying the separate influences of perceptual processes and decisional processes within and across tasks. Good accounts of the identification data were obtained from an initial perceptual representation derived from perceptual matching. The same perceptual representation provided a good account of the categorization data, except when selective attention to one stimulus dimension was required. Selective attention altered the perceptual representation by decreasing the perceptual variance along the attended dimension. These findings suggest that a complete understanding of identification and categorization performance requires an understanding of perceptual and decisional processes. Implications for other psychological tasks are discussed.     

Temperament and migration patterns in Finland

Migration is a central determinant of population dynamics and structure. We examined whether three major temperament traits--sociability, emotionality, and activity--predicted migration propensity, selective urban-rural migration, and migration distance in a 9-year prospective study in Finland. The participants were Finnish women and men (N= 1,733) ages 15 to 30 years at baseline. The home municipality's position on the urban-rural continuum was assessed on the basis of the municipality's population density. We found that high sociability predicted migration to urban areas and longer migration distances. High activity increased general migration propensity (including migration to both urban and rural areas). High emotionality increased the likelihood of leaving the home municipality and decreased migration distances, but was not associated with selective urban-rural migration. These data suggest that temperament predicts the self-selection of environments on a demographic scale and may be relevant in understanding population dynamics.     

The Role of Atomic Repertoires in Complex Behavior

Evolution and reinforcement shape adaptive forms and adaptive behavior through many cycles of blind variation and selection, and therein lie their parsimony and power. Human behavior is distinctive in that this shaping process is commonly "short circuited": Critical variations are induced in a single trial. The processes by which this economy is accomplished have a common feature: They all exploit one or more atomic repertoires, elementary units of behavior each under control of a distinctive stimulus. By appropriate arrangements of these discriminative stimuli, an indefinite number of permutations of atomic units can be evoked. When such a permutation satisfies a second contingency, it can come under control of the relevant context, and the explicit arrangement of discriminative stimuli will no longer be required. Consequently, innovations in adaptive behavior can spread rapidly through the population. A consideration of atomic repertoires informs our interpretation of generalized operants and other phenomena that are otherwise difficult to explain. Observational learning is discussed as a case in point.