Low-energy boron implants into silicon: A molecular dynamics simulation study of implants into a stepped surface

Molecular dynamics simulations have been conducted to study implantation of boron with a low kinetic energy (E _k in the range 5 eV) into the silicon surface. The bombarded surface has a realistic stepped structure and the geometry of the step edge is taken from the theory of Chadi (1987, Phys. Rev. Lett., 59, 1691). It is found that reflection is the more common event. However subsurface implants and adatom formations are also observed. The effect of the step morphology is important and different trajectories are observed if the ions hit steps of different shapes.     

Boron impurities on a vicinal Si(100) surface: A study of structural properties and binding energies

The equilibrium locations of boron on the steps of the Si(100) surface have been studied using the Hartree-Fock method at the semiempirical level. The step is represented by a cluster of silicon atoms whose dangling bonds are saturated by hydrogen atoms. The boron impurity is moved in the step in substitutional and interstitial positions and the optimal configuration of the step containing the impurity is evaluated from a steepest-descent energy minimization. The study focuses on the dependence of the properties of the boron-step interaction on the shape of the step. These effects are analysed in the light of the features of boron absorbed on the flat surfaces and in the bulk, which have been widely studied.     

Kinetics of non-equilibrium step structure

The non-equilibrium structure of a [100]step on a (001) surface of a sc crystal is studied by introducing a new model in which densities of adatoms and vacancies on the step are treated as independent variables and the motion of kinks along the step is taken into account. The structural change of the step is found to be of a relaxational type with a relaxation time that is a function of temperature and degree of supersaturation. An approximate formula for the steady-state density of kinks for the case of low temperatures and low supersaturations is obtained.     

The effects of leadership style and exercise program choreography on enjoyment and intentions to exercise

ObjectiveThe purpose of the study was to examine the independent (main) and interactive effects of leadership style and exercise program choreography on the enjoyment and future exercise intentions of novice female exercisers.DesignA randomized 2 (leadership style)×2 (exercise choreography) factorial in which a manipulation of leadership style (instructionally and motivationally enriched vs. bland) was crossed with a manipulation of exercise choreography style consisting of either a restricted or a varied set of exercises.MethodsNovice female exercisers (N=75) completed measures of exercise enjoyment and intentions to engage in future step aerobics classes following a 40-minute introductory session of step aerobics.ResultsSignificant (p<0.05) main effects were detected for leadership style and exercise choreography on enjoyment. Socially enriched leadership and varied choreography were associated with greater enjoyment. There were no main or interaction effects for exercise intention.ConclusionsResults show that social and structural factors impact on positive psychological outcomes in a structured exercise setting. Practitioners are encouraged to use these and previous findings to plan introductory exercise sessions. Future research should look at the impact of leadership style, choreography, and class group dynamics on behavioral manifestations such as adherence.     

Unplanned pregnancies and abortion counselling: Some thoughts on unconscious motivations

Abstract

My experience of abortion counselling¹ over ten years has shown me the importance of understanding the unconscious dynamics behind an unplanned and unwanted pregnancy. Unless these dynamics are made conscious and understood, the experience of abortion may have to be repeated again and again. Both becoming pregnant and having an abortion often involve unconscious conflicts and fantasies originating in a woman's early development and reflecting her relationship with her mother. These may be acted out via an unplanned pregnancy and decision to have an abortion. The central task of abortion counselling is to address and make links with the unconscious processes, and in particular help the pregnant woman recognize and acknowledge her ambivalent feelings. In this way the counselling makes use of the opportunity to reflect provided by the crisis situation of the pregnancy.     

Electron irradiation damage in SnO

In a study of radiation effects in SnO we have found that electron-beam damage is observable from changes in a high-resolution electron microscopy image or electron diffraction pattern. The early stage of the damage is not accompanied by a change in composition or a loss of crystallinity. The dose required for this damage (about 600 C cm^?2) is approximately independent of electron energy (between 100 and 400 keV) and specimen temperature (between 100 and 300 K). The damage is believed to start with displacement of oxygen atoms from their lattice position through a radiolytic mechanism with an efficiency of approximately 10^?4.     

Descartes and some predecessors on the divine conservation of motion

Here I reexamine Duhem's question of the continuity between medieval dynamics and early modern conservation theories. I concentrate on the heavens. For Aristotle, the motions of the heavens are eternally constant (and thus mathematizable) because an eternally constant divine Reason is their mover. Duhem thought that impetus and conservation theories, by extending sublunar mechanics to the heavens, made a divine renewer of motion redundant. By contrast, I show how Descartes derives his law of conservation by extending Aristotelian celestial dynamics to the earth. Descartes argues that motion is intrinsically linear, not circular. But he agrees that motion is mathematically intelligible only where divine Reason moves bodies in a constant and eternal motion. Descartes strips bodies of active powers, leaving God as the only natural mover; thus both celestial and sublunar motions are constant, and uniformly mathematizable. The law of conservation of the total quantity of motion is an attempt to harmonize the constancy derived a priori with the phenomenal inconstancy of sublunar motions.I would like to thank Daniel Garber, Alison Laywine, and Ian Mueller for their comments. Since I have not seen a text of Professor Westman's remarks, either before or after he delivered them, I cannot respond to his criticisms.     

Annealing of europium-implanted silicon by nanosecond ion-beam pulses

Ion implantation into Si(100) was made with Eu⁺ ions at 25 keV to doses of 1.2 x 10¹⁵ and 1.2 x 10¹⁶ ions cm^-2     

Grand Unified Theories of the Brain Need Better Understanding of Behavior: The Two-Tiered Emergence of Function

Abstract

Over the last few decades, neuroscience and various associated disciples have expanded enormously in terms of output, tools, methods, concepts, and large-scale projects. In spite of these developments, the principles underlying brain function and behavior are yet only partially understood. We claim that brain functioning requires the elucidation of the rules associated with all possible task realizations, rather than targeting the activity underlying a specific realization. A first step in that direction was taken by approaches focusing on dynamical structures underlying task performances, as exemplified by coordination dynamics. Its theoretical foundation owes much to Haken’s synergetics, which provides a formalism through which the degrees of freedom associated with high-dimensional systems may be effectively reduced to one or a few functional variables in the vicinity of phase transitions. The recent theoretical development of structured flows on manifolds (SFM) allows the employment to a potentially broader range of applications. Here we expand the SFM framework and propose that the emergent two-tiered fast–slow dynamics may be a basic mathematical organization underlying the architecture of brain and behavior dynamics. Finally, along a few examples, we illustrate how this framework allows for the incorporation of notions cardinal to ecological psychology.     

On the low-frequency vibrational spectrum of water

A new assignment is proposed for the low-frequency region of the vibrational spectrum of water, based on a comparison of the times of relevant occurring events. The time-matching is made between the dynamics of the rupture and formation time of the hydrogen bond, and the so-called bending and stretching oscillation periods of the O–H ··· O tetrahedral network. The same assignment also emerges by comparing thermal and solute concentration effects. Furthermore, a critical re-examination of the literature already existing on the subject corroborates the now proposed assignments for the modes at 60 and 170 cm^?1. These are considered to arise first from a transverse acoustic phonon with a low-frequency contribution sensitive to temperature and concentration effects, and second from external motions such as translations or restricted rotations of small water clusters inside a cage, and subjected to its potential field.     

Self-efficacy,mental models and team adaptation: A first approach on football and futsal refereeing

ObjectiveWithin the football and futsal refereeing context, even though referees work within teams, there is very little research considering the implications of team dynamics. In response, this study starts to address this gap in the literature by investigating the moderating effect of mental models on the relationship between self-efficacy beliefs and perceptions of team adaptation within the exciting context of professional and national football and futsal refereeing.DesignWe obtained online questionnaires from 339 active football and futsal referees within the National and Professional league at two distinct points (April and May) within the football season.ResultsSelf-efficacy beliefs were positively associated with perceptions of team adaptation (only for football referees). Mental models were positively associated with team adaptation. Likewise, the moderation between mental models and self-efficacy beliefs was positively associated with perceptions of team adaptation. However, such an effect was only significant at the futsal referees’ level.ConclusionThis study emphasises the importance of mental models for team adaptation and the importance of self-efficacy beliefs in predicting perceptions of team adaptation. We hope that this study represents the first step in a greater appreciation of the salience of team dynamics and their impact on football and futsal referees’ performance and that future research can build upon our work.     

The temperature dependence of the optical dispersion parameters in Si and Ge

Abstract

In Si and Ge, the optical dispersion parameters (single-oscillator energy E_o , dispersion energy E_d and bond energy gap E_g developed by Wemple and DiDomenico, and Phillips) have been analysed in the temperature range 100-300 K using data obtained by Icenogle et al. E_o and E_g exhibit a very small temperature dependence in both materials. The thermal coefficients of the dispersion energy, dE_d/dT, have opposite signs (Si, –41·9 × 10^?4eVK^?1; Ge, +37·7 × 10^?4eVK^?1).     

Growth of diamond crystals by combustion synthesis

Abstract

Low-pressure synthesis of diamond by activated chemical vapour deposition processes is attractive for producing diamond films for optical and electronic (i.e. non-abrasive) applications because of the ability of these processes to produce these films in large dimensions. The low growth rate (about 1 μm h^?1) has, however, precluded these processes for abrasive grain production on simple economic grounds. With the introduction of combustion synthesis of diamond at growth rates exceeding 100μmh^?1, this barrier seems less formidable than it once did. The synthesis of large (about 200 μm) well formed single crystals of diamond by the combustion process with growth rates of about 100μm h^?1, reported here, offers an opportunity to explore the potential of this process for abrasive grain production.     

Davidson on the Identity Theory

Abstract

… if we bear well in mind the scope of our senses and what it is exactly that reaches our faculty of thinking by way of them, we must admit that in no case are the ideas of things presented to us by the senses just as we form them in our thinking. So much so that there is nothing in our ideas which is not innate to the mind or the faculty of thinking, with the sole exception of those circumstances which relate to experience, such as the fact that we judge that this or that idea which we now have immediately before our mind refers to a certain thing situated outside us. We make such a judgment not because these things transmit the ideas to our mind through the sense organs, but because they transmit something which, at exactly that moment, gives the mind occasion to form these ideas by means of the faculty innate to it. Nothing reaches our mind from external objects through the sense organs except certain corporeal motions… in accordance with my own principles. But neither the motions themselves nor the figures arising from them are conceived by us exactly as they occur in the sense organs, as I have explained at length in my Optics. Hence it follows that the very ideas of the motions themselves and of the figures are innate in us. The ideas of pains, colors, sounds and the like must be all the more innate if, on the occasion of certain corporeal motions, our mind is to be capable of representing them to itself, for there is no similarity between these ideas and the corporeal motions.     

Orchiectomy in transgender individuals: A motivation analysis and report of surgical outcomes

Abstract

Background: Different surgical procedures are available for transgender women wishing to undergo genital gender-affirming surgery.

Aim: To assess preoperative motivations, the frequency of orchiectomy procedures, and postoperative outcomes of orchiectomy in transgender individuals.

Methods: All transgender individuals who underwent orchiectomy in the period between January 2012 and January 2020 at our institution were retrospectively identified. A chart study was conducted, recording motivations, demographics, perioperative characteristics and surgical outcomes. The frequency of orchiectomy and vaginoplasty procedures during the study period were determined and compared.

Results: During the study period, an increase of performed orchiectomy procedures was observed. The orchiectomy/vaginoplasty ratio was 0.01–0.07 in the period 2012–2018 and 0.24 in 2019. A total of 43 transgender individuals were retrospectively identified. Sixteen (37%) initially wished to undergo a vaginoplasty, but did not meet institutional requirements (nonsmoker, BMI < 30kg/m²) or were not eligible for vaginoplasty surgery because of interfering somatic or mental health issues. Fourteen (33%) individuals who underwent orchiectomy regarded it as a preceding step to a future vaginoplasty procedure. Out of these fourteen, one person is now on the waiting list for vaginoplasty surgery. Thirteen (30%) others did not report a desire to pursue vaginoplasty in the future. This was mostly motivated by the absence of genital dysphoria or motivations related to their gender identity, with a desire to discontinue anti-testosterone treatment. The postoperative course was uncomplicated in 39 (91%) individuals.

Conclusion: In the Netherlands, especially in the last year, the frequency of orchiectomy procedures has increased. Reasons that people chose to undergo this procedure include: not being eligible for a vaginoplasty procedure, seeing it as a preceding step to a possible future vaginoplasty or other identity-related motivations (i.e., non-binary gender identification or absence of genital dysphoria).     

Adolescents' social anxiety dynamics in a latent transition analysis and its psychosocial effects

Background/ObjectiveThe present study aims to explore the dynamics of social anxiety profiles in adolescents over time and the psychosocial effects these dynamics have.MethodA representative sample of Andalusian (southern Spain) adolescents in Secondary Education was drawn. The study used single-stage stratified cluster sampling. A total of 2,140 students aged 11-16 years (47% girls; M_ageT1 = 13.68, SD = 1.27) were involved at two time points with a six-month interval.ResultsThe results provided a four-profile structure: low social anxiety, moderate cognitive disturbance, high with difficulties in new situations, and high social anxiety. The latent transition analysis showed a stability in the social anxiety profiles of between 58%-61%. Those adolescents who remained in or transitioned to profiles with higher social anxiety scored worse on peer adjustment, peer victimization and subjective well-being.ConclusionsThe study may contribute the improvement of the psychological treatments in social anxiety and reduce adverse effects on peer relationships and well-being by distinguishing the profiles and their dynamics.     

To Pass or Not to Pass: A Mathematical Model for Competitive Interactions in Rugby Union

ABSTRACT. Predicting behavior has been a main challenge in human movement science. An important step within the theory of coordination dynamics is to find out the rules that govern human behavior by defining order parameters and control parameters that support mathematical models to predict the behavior of a system. Models to describe human coordination have been focused on interlimb coordination and on interpersonal coordination in affiliative tasks but not on competitive tasks. This article aims to present a formal model with two attractors to describe the interactive behavior on a 2v1 system in rugby union. Interpersonal distance and relative velocity critical values were empirically identified and were included as task constraints that define the attractor landscape. It is shown that using relative velocity as a control parameter the model offers reasonable prediction concerning the decision-making process. The model has the plasticity to adapt to other settings where interpersonal distances and relative velocities amongst system components act as significant task constraints.     

Fluctuating dynamics of perceived exertion in constant-power exercise

ObjectivesTo reveal and study the fluctuating dynamics of perceived exertion (PE) during constant-power exercise performed under different conditions (duration, intensity, and termination).DesignA pilot and two subsequent experimental studies were performed. The studies consisted of manipulating workload and measuring fluctuating perceived exertion dynamics throughout the cycling task.MethodsIn a pilot study Borg's rating of perceived exertion (RPE) was measured every 15 s in 2 groups of 9 participants each (using RPE 6-20 and CR10 scales, respectively) cycling at heavy intensity until volitional exhaustion. The percentage of participants alternating increased and decreased RPE values (fluctuating dynamics) was calculated. In 2 subsequent experiments PE changes (increase/decrease perceptions) were reported when occurring in 2 groups of 13 participants cycling at a moderate intensity for 30 and 60 min, respectively (Experiment 1), and in another group of 12 participants cycling at heavy intensity until volitional exhaustion (Experiment 2). The individual time series of “increase”/“decrease” reports were divided into 5 non-overlapping temporal windows, and the percentages of “PE increase” were calculated for each window.ResultsIn the pilot study 66.6% (RPE 6-20 group) and 33.3% (CR10 group) of the participants showed an RPE fluctuating dynamics during the exercise. However, all participants showed a clear PE fluctuating dynamics during the moderate and heavy intensity exercises performed in Experiment 1 and Experiment 2, respectively. Nevertheless, a transition towards a PE non-fluctuating dynamics (dominated by “PE increase” reports) was noticed in Experiment 2 while approaching volitional exhaustion.ConclusionsPE seems to have a dominant fluctuating dynamics during constant-power cycling performed under different conditions (duration, intensity, and termination) that changes towards a non-fluctuating dynamics when approaching the volitional exhaustion point.     

Toward a three-dimensional conceptualization of performance anxiety: Rationale and initial measurement development

ObjectivesAn integrated three-dimensional model of performance anxiety was constructed to offer an alternative conceptualization that may contribute to understanding of the complex anxiety–performance relationship. In particular, the adaptive potential (producing positive effects) of anxiety was acknowledged explicitly by including a regulatory dimension. This model is characterized by five subcomponents, with worry and self-focused attention representing cognitive anxiety, autonomous hyperactivity and somatic tension representing physiological anxiety, and perceived control representing the regulatory dimension of anxiety. The overview of the conceptual framework and the underlying rationale are presented.DesignAs a necessary first step towards model testing, an initial measure was developed and the factorial validity of the model was investigated.MethodConfirmatory factor analysis was used in two independent samples (N = 286, 327) in a wide context of sports performance.ResultsA 25-item measure of performance anxiety was established. Findings of CFA revealed support for a three-dimensional first-order model.ConclusionsAlthough the present model of performance anxiety was best presented as a three-dimensional first-order structure, the integrity of the conceptual framework is considered intact as such a factor structure distinctly reflects the three major processes (i.e., cognitive, physiological and regulatory) that are proposed to be activated in the anxiety dynamics from a broad cognitive perspective.