This research compares email request strategies used by native speakers of American English and Brazilian Portuguese English as second language speakers. The results of the research provide a valuable contribution to the field ESL/EFL instructions. They identify syntactic and lexical devises native and non-native speakers of English use when composing email requests to their professors. This type of information can be used by ESL/EFL instructors for developing effective classroom materials for teaching non-native speakers of English how to write appropriate emails in academic settings.

TITLE: Postural control: the influence of vision to multi-muscle synergies

PRESENTATION TYPE: Research Report – Oral

AUTHORS/INSTITUTIONS:

A. Degani¹, A. Danna-dos-Santos¹, C. Leonard¹.

¹School of Physical Therapy and Rehabilitation Science, University of Montana, Missoula, MT.

Significance:

Falls are the leading cause of injury, deaths, and hospital admissions for traumatic injuries among people aged 65 years and older (Centers for Disease Control and Prevention, 2013). The costs related to the morbidity resulting from these falls are increasing dramatically. In order to reduce costs, increase quality of life, and prolong the longevity of the US work force, several studies are currently focusing on how to assess the risk of falls and prevent their occurrence. However, very little efforts is concentrated to the understanding of the neurophysiological mechanisms associated with upright postural control. Posture and postural reactions to mechanical perturbations require a precise harmonic modulation of the activity of multiple muscles. It is our premise that a comprehensive understanding of such neurophysiological mechanisms may improve current methods and/or result in the development of new approaches of assessing the risk and managing comorbidities generated by fall-related injuries. This study was designed to investigate the role of common neural inputs to the organization of multi-muscle synergies and the possible effects of disruption of visual input to this mechanism of control.

Hypotheses:

We hypothesize that (1) the central nervous system uses correlated neural inputs to coordinate the formation of postural muscle synergies, and (2) this mechanism is affected by the interruption of visual input.

Methods:

Our hypotheses were investigated by analyzing the strength and distribution of correlated neural inputs to postural muscles, as measured by electromyography (EMG) coherence, during the execution of a quiet stance tasks. Nine healthy participants, five females and four males with mean age of 26 years (± 6.1 SD) performed the task of maintaining a quiet stance on a force platform for 30 seconds under two experimental conditions: availability or absence of visual information (open eyes and closed eyes respectively). Center of pressure displacement were recorded by the force platform, and the activity of six postural muscles (soleus, biceps femoris, lumbar erector spinae, tibialis anterior, rectus femoris, and rectus abdominis) were recorded by surface electrodes. Intermuscular EMG-EMG coherence estimates were computed for all possible muscle pairs formed by these muscles. Pooled coherence estimations were also computed for anterior and posterior muscles.

Results:

Intermuscular coherence was found only to be significant within a distinct frequency band bounded between 1-10 Hz; and when visual information was available (“open eyes” trials). This significant coherence occurred only for muscle pairs formed solely by either posterior or anterior muscles. No synchronization patterns were observed for pairs of muscles formed by one anterior and one posterior muscle. In addition, the absence of visual information caused a significant decrease in intermuscular coherence estimates profiles within this same frequency band of 1-10Hz.

Conclusion:

These findings are consistent with the hypothesis that synchronization patterns of postural muscular activation are organized by correlated neural inputs. Moreover, the intermuscular coherence decreases significantly when the same task was performed under short-term absence of visual information.

Clinical Relevance:

Increased risk of falls is possibly linked to impairments in the ability of the neuromuscular system to generate optimal multi-muscle synergies. This impairment can result from several factors, such as poor vision caused by maculopathies. This study has provided a step forward towards the understanding of the mechanisms involved in coordination of multiple postural muscles, and the role of the vision on balance control. In addition, this study prepares the foundation for future clinical studies focusing on balance interventions for individuals with postural control disorders and/or visual impairments.

Juvenile crime is a serious issue in the United States. Juveniles, those who are under 18 years of age, account for approximately 24% of the population (Census Bureau 2014). This segment of the population is responsible for over 10% of all crime committed in the United States (FBI 2012). Although secure confinement has been identified as one of the most significant contributors to a juvenile’s future risk of recidivism (Bezruki, Varana, and Hill 1999), few studies have directly examined the link between juvenile secure confinement and recidivism. Using official data from Montana’s Juvenile Court Accountability and Tracking System (JCATS) (n=2,897), this study contributes to the literature. The findings are based on propensity score matching to obtain a more comprehensive estimate of the influence placement in secure confinement has on a juvenile’s risk of recidivism. In the investigation, recidivism refers to involvement in delinquency within one year, following juvenile court intervention, including release from secure confinement. Close to 70% of juveniles released from secure confinement are involved in recidivism within one year (Bezruki, Varana, and Hill 1999). Propensity score matching approximates the conditions of a controlled experiment. Treatment can include any form of intentional intervention, in this case, placement in secure confinement. Treated cases are matched to non-treated cases based on their propensity to receive treatment (Apel and Sweeten 2010). This statistical analysis eliminates some of the problems of causal inference by ensuring that matched individuals are statistically equivalent. While controlling for covariates related to juvenile recidivism, propensity score matching allows for the estimation of the causal effect of treatment (Guo and Fraser 2015). Conclusions from this research will inform practitioners in the area of juvenile justice on the realities of a practice that has been described as dangerous (Holman and Ziedenberg 2006). Practitioners and researchers alike will be interested in the unique effect of a placement in secure confinement on a juvenile’s risk of recidivism. In addition, results from prior studies contrasted with results from this investigation have the potential to inform other researchers of a more valuable tool for analyzing quasi-experimental data.