Influence of delayed muscle reflexes on spinal stability: Model-based predictions allow alternative interpretations of experimental data

Model-based calculations indicate that reflex delay and reflex gain are both important for spinal stability. Experimental results demonstrate that chronic low back pain is associated with delayed muscle reflex responses of trunk muscles. The aim of the present study was to analyze the influence of such time-delayed reflexes on the stability using a simple biomechanical model. Additionally, we compared the model-based predictions with experimental data from chronic low back pain patients and healthy controls using surface-electromyography. Linear stability methods were applied to the musculoskeletal model, which was extended with a time-delayed reflex model. Lateral external perturbations were simulated around equilibrium to investigate the effects of reflex delay and gain on the stability of the human lumbar spine. The model simulations predicted that increased reflex delays require a reduction of the reflex gain to avoid spinal instability. The experimental data support this dependence for the investigated abdominal muscles in chronic low back pain patients and healthy control subjects. Reflex time-delay and gain dependence showed that a delayed reflex latency could have relevant influence on spinal stability, if subjects do not adapt their reflex amplitudes. Based on the model and the experimental results, the relationship between muscle reflex response latency and the maximum of the reflex amplitude should be considered for evaluation of (patho) physiological data. We recommend that training procedures should focus on speeding up the delayed reflex response as well as on increasing the amplitude of these reflexes.     

Are good students desirable friends? Evidence for friendship selection among elementary students / ¿Son los buenos estudiantes amigos deseables? Evidencia para la selección de amistad entre estudiantes de educación primaria

Abstract

This study assesses the relationship between friendship networks and academic performance among third graders from one school in Santiago, Chile. Longitudinal social network analysis (RSiena) was used to test whether friendship selection is driven by academic performance and if befriended peers tend to influence each other on their academic performance, including gender as a covariate. Results show a positive relationship between academic performance and number of friendship nominations received, and a higher probability of same-gender friendships. Students with higher academic achievement are more likely to be nominated as friends, especially by peers with lower academic achievement. These results suggest that elementary students value high performance as a desirable characteristic in their friends.     

The Developmental Roots of Borderline Personality Disorder in Early Attachment Relationships: A Theory and Some Evidence

The paper suggests a way of understanding borderline personality disorder in terms of the failure of a secure base. We begin with an account of optimal self-development in a secure attachment context, highlighting the importance of the caregiver's ability to help the small child think about his own and others' minds. This optimal self-development is crucial in developing the child's capacity for mentalization, which can enhance his resilience in the face of later trauma. We discuss the impact of attachment trauma in later development, arguing that the extent of this impact depends on how well early attachment relationships facilitated the capacity for mentalization. We identify some of the consequences for the representations of the internal world of a failure of mentalization that may follow trauma in individuals made vulnerable by genetic predisposition or disorganized early attachment. We link these features to the clinical presentation associated with borderline personality organization. Finally, some of the necessary characteristics of successful psychotherapeutic treatment of borderline personality disorder are briefly considered.     

Probability of Criminal Acts of Violence: A Test of Jury Predictive Accuracy

The ability of capital juries to accurately predict future prison violence at the sentencing phase of aggravated murder trials was examined through retrospective review of the disciplinary records of 115 male inmates sentenced to either life (n = 65) or death (n = 50) in Oregon from 1985 through 2008, with a mean post‐conviction time at risk of 15.3 years. Violent prison behavior was completely unrelated to predictions made by capital jurors, with bidirectional accuracy simply reflecting the base rate of assaultive misconduct in the group. Rejection of the special issue predicting future violence enjoyed 90% accuracy. Conversely, predictions that future violence was probable had 90% error rates. More than 90% of the assaultive rule violations committed by these offenders resulted in no harm or only minor injuries. Copyright © 2013 John Wiley & Sons, Ltd.     

Relationships Between Leader-Contingent and Non-contingent Reward and Punishment Behaviors and Subordinates’ Perceptions of Justice and Satisfaction, and Evaluation of the Moderating Influence of Trust Propensity, Pay Level, and Role Ambiguity

Purpose

This research evaluates how reward and punishment behaviors are related to employee satisfaction, and how perceptions of justice mediate the effects of these behaviors. This study also seeks to examine the connection between some boundary conditions and the efficacy of reward and punishment behaviors.

Design/Methodology/Approach

Data were collected using questionnaires, and hypotheses were tested using a sample of 3,065 managers from 41 business units.

Findings

We found that contingent financial and social rewards were positively related to fairness and satisfaction, whereas punishment behaviors exert a negative influence. Findings reveal that high-trust propensity and low-pay level strengthen the positive influence of rewards on distributive justice, whereas high role ambiguity increases the positive effect of reward behaviors and the negative influence of non-contingent punishment (NCP) on superior satisfaction.

Implications

This study provided evidence that using contingent rewards is more effective in promoting positive attitudes at work than using contingent punishments. Our findings add to the evidence that organizations would benefit from encouraging their managers to use financial and social rewards and reducing the administration of NCP among performing employees.

Originality/Value

This study represents a first attempt to examine an integrated model of the effects of reward and punishment behaviors. It also contributes to this field by empirically evaluating the impact of individual and situational boundary conditions in the efficacy of these leader behaviors.     

First and second language in the brain: Neuronal correlates of language processing and spelling strategies

This study explores oscillatory brain activity by means of event-related synchronization and desynchronization (%ERS/ERD) of EEG activity during the use of phonological and orthographic-morphological spelling strategies in L2 (English) and L1 (German) in native German speaking children. EEG was recorded while 33 children worked on a task requiring either phonological or orthographic-morphological spelling strategies. L2 processing elicited more theta %ERS than L1 processing (particularly at bilateral frontal and right posterior parietal sites) which might suggest a stronger involvement of semantic encoding and retrieval of the less familiar L2. The highest level of theta %ERS was revealed for the orthographic-morphological strategy in L2 which might indicate a more intense way of lexical retrieval compared to the phonological strategy in L2 and the orthographic-morphological strategy in L1. Analyses moreover revealed that phonological processing (both in L1 and L2) was associated with comparatively strong left-hemispheric %ERD in the upper alpha frequency band.     

Selling and Sales Management in Action Examining the Bases Utilized for Evaluating Salespeoples' Performance

Evaluating salespeoples' performance is an important task for sales managers. However, little is known about what bases are used by sales managers to evaluate the performance of their salespeople. A study was conducted to determine the bases actually used by sales managers and the results were compared with a study conducted in 1983. Findings indicate more emphasis on profit and cost control, a continued reliance on qualitative measures, and a wide variety of bases being utilized to evaluate the performance of salespeople. Furthermore, the stability of results, across a wide variety of respondent job titles as well as business types and sizes, indicates a good deal of generalizability to other firms.     

How to Improve Your College Recruiting Program

In today's ever-changing business environment, teamwork has emerged as a requirement for success. As industry faces this paradigm shift, a formal team structure is emerging that goes beyond that proposed by previous selling/buying center researchers. Accordingly, a conceptualization of the functions and roles of these formalized selling and buying teams is proposed as a starting point for future investigations. The movement toward formal self-directed teams is explored, updated definitions of the selling and buying teams are proposed, and the functions and roles of each team are reviewed. Key constructs and organizational implications also are discussed.     

Leaders in Selling and Sales Management: John H. Patterson

Although there is much controversy regarding the teaching of ethics in our universities today, ethical dilemmas are a part of the reality of the sales force. This study examines the differences in the perceptions of sales management students and practitioners in an ethical situation. The results suggest that gender does have an impact on the severity of the consequences and that there are significant differences between the perceptions of practitioners and sales management students.