THE EFFECT OF THE STM TIP ON SI(100) RECONSTRUCTED SURFACES

We present a theoretical study of the effects of the STM tip on the geometry of Si(100) reconstructed surfaces. The energy barrier to switching between different reconstructions is also discussed. We use a molecular dynamics method and self-consistent forces to simulate the time-dependent behaviour of the surface atoms. The molecular orbital calculations are performed at the CNDO level using a cluster model. Our results indicate significant differences for positively and negatively biased tips. The thermally induced rocking of surface dimers is inhibited by the application of a positive bias to the tip and it is promoted by a negative bias. These bias-dependent effects may offer a plausible explanation for the bias dependence of STM images of this surface

EFFECTS OF THE STM TIP ON ADSORBATE IMAGE

Scanning tunnelling microscopy provides atomic scale information about surface topography and electronic structure. However, the way the tip affects the STM image cannot always be neglected. We present a theoretical study of the effect of the non-uniform electric field of the tip on STM image of adsorbed molecules using Bardeen's approach. Self-consistent geometry optimization and wave-function calculations have been carried out within the CNDO approximation in a cluster model. Our results indicate significant effects. Thus for adsorbed CO on metal, the molecules reorient because of the tip, and the image is changed qualitatively as well as quantitatively. This may explain the lack of observation of CO at low coverage by STM. Our results also suggest the STM might be used for molecular modification

But Is It Real? A Review of Research on Enneagram

One of the most common questions I am asked when introducing people to the Enneagram goes something along the lines of: “Yes, but is it real? What scientific evidence is there?” It was exactly that question that prompted me to do my PhD research a few years ago. I could see the Enneagram worked for me but I wanted to know if it could stand up to rigorous psychological research. In this article, I have tried to summarise the published research on the Enneagram so that next time someone asks you that question you can answer confidently, “Yes, there is good evidence of its validity, let me tell you about it…

Measuring the Effects of Self-Awareness: Construction of the Self-Awareness Outcomes Questionnaire

Dispositional self-awareness is conceptualized in several different ways, including insight, reflection, rumination and mindfulness, with the latter in particular attracting extensive attention in recent research. While self-awareness is generally associated with positive psychological well-being, these different conceptualizations are also each associated with a range of unique outcomes. This two part, mixed methods study aimed to advance understanding of dispositional self-awareness by developing a questionnaire to measure its outcomes. In Study 1, expert focus groups categorized and extended an initial pool of potential items from previous research. In Study 2, these items were reduced to a 38 item self-report questionnaire with four factors representing three beneficial outcomes (reflective self-development, acceptance and proactivity) and one negative outcome (costs). Regression of these outcomes against self-awareness measures revealed that self-reflection and insight predicted beneficial outcomes, rumination predicted reduced benefits and increased costs, and mindfulness predicted both increased proactivity and costs. These studies help to refine the self-awareness concept by identifying the unique outcomes associated with the concepts of self-reflection, insight, reflection, rumination and mindfulness. It can be used in future studies to evaluate and develop awareness-raising techniques to maximize self-awareness benefits while minimizing related costs

Bounds on the satisfiability threshold for power law distributed random SAT

Propositional satisfiability (SAT) is one of the most fundamental problems in computer science. The worst-case hardness of SAT lies at the core of computational complexity theory. The averagecase analysis of SAT has triggered the development of sophisticated rigorous and non-rigorous techniques for analyzing random structures. Despite a long line of research and substantial progress, nearly all theoretical work on random SAT assumes a uniform distribution on the variables. In contrast, real-world instances often exhibit large fluctuations in variable occurrence. This can be modeled by a scale-free distribution of the variables, which results in distributions closer to industrial SAT instances. We study random k-SAT on n variables, m = ϵ(n) clauses, and a power law distribution on the variable occurrences with exponent β. We observe a satisfiability threshold at β≤(2k-1)/(k-1). This threshold is tight in the sense that instances with β ≥ (2k-1)/(k-1)-ϵ for any constant ϵ > 0 are unsatisfiable with high probability (w. h. p.). For β > (2k-1)/(k-1)+ ϵ, the picture is reminiscent of the uniform case: instances are satisfiable w. h. p. for sufficiently small constant clause-variable ratios m/n; they are unsatisfiable above a ratio m/n that depends on β

Can competencies at selection predict performance and development needs?

Purpose – The purpose of this paper is to explore the utility of an organisation-wide competency framework, linking competency ratings at selection to later development needs and job performance. Design/methodology/approach – Candidates’ scores at a management selection event were compared to their performance appraisal scores on the same competencies six to 12 months later (n=58). Scores on numeracy and profit and loss tests were also collected at the selection event and related to subsequent performance (n=207) and development needs. Findings – Competency ratings at performance appraisal were significantly lower than at selection interview. Correlations between ratings at interview and at performance appraisal were generally weak, though one (Understanding the Business) showed significant relationships with five of the seven performance appraisal competencies. In addition, competency ratings were related to employee turnover and managerial development needs. Research limitations/implications – Although competencies were clearly defined, inter-rater variations may have occurred which obscure the relationships. However, it is of interest that a single competency at selection (Understanding the Business) seems to have the greatest effect on performance, employment outcome and development needs. Practical implications – A competency framework that is embedded in both selection and performance ratings can provide the organisation with a clearer understanding of what determines managerial success, as well as informing better selection decisions. This study also raises the issue that performance ratings may be influenced more by a manager's ability to understand the business than by any other competencies. Originality/value – The use of a longitudinal design provides unique evidence of the relationship between competency ratings at selection and later performance, employment outcome and development needs

Engineering the Fab fragment of the anti-IgE omalizumab to prevent Fab crystallization and permit IgE-Fc complex crystallization

Immunoglobulin E (IgE) plays a central role in the allergic response, in which cross-linking of allergen by Fc[epsilon]RI-bound IgE triggers mast cell and basophil degranulation and the release of inflammatory mediators. The high-affinity interaction between IgE and Fc[epsilon]RI is a long-standing target for therapeutic intervention in allergic disease. Omalizumab is a clinically approved anti-IgE monoclonal antibody that binds to free IgE, also with high affinity, preventing its interaction with Fc[epsilon]RI. All attempts to crystallize the pre-formed complex between the omalizumab Fab and the Fc region of IgE (IgE-Fc), to understand the structural basis for its mechanism of action, surprisingly failed. Instead, the Fab alone selectively crystallized in different crystal forms, but their structures revealed intermolecular Fab/Fab interactions that were clearly strong enough to disrupt the Fab/IgE-Fc complexes. Some of these interactions were common to other Fab crystal structures. Mutations were therefore designed to disrupt two recurring packing interactions observed in the omalizumab Fab crystal structures without interfering with the ability of the omalizumab Fab to recognize IgE-Fc; this led to the successful crystallization and subsequent structure determination of the Fab/IgE-Fc complex. The mutagenesis strategy adopted to achieve this result is applicable to other intractable Fab/antigen complexes or systems in which Fabs are used as crystallization chaperones