Subgroups and Orbits by Companion Matrix in Three Dimensional Projective Space

الهدف من هذا البحث هو انشاء زمر جزئية دورية من الزمرة الخطية العامة الإسقاطية على الحقل  من المصفوفة المصاحبة ، ثم تكوين أغطية بدرجات مختلفة في . تم إعطاء الخصائص الهندسية لهذه الأغطية كتوزيعات القطع و توزيعات الدليل ، وتحديد فيما إذا كانت كاملة. كذلك, تجزئة  الى خطوط غير متقاطعة تم دراسته.The aim of this paper is to construct cyclic subgroups of the projective general linear group over  from the companion matrix, and then form caps of various degrees in . Geometric properties of these caps as secant distributions and index distributions are given and determined if they are complete. Also, partitioned of  into disjoint lines is discussed

Structural relationship of leadership qualities with site workers issues for Saudi Arabia’s Construction Industry

Construction industry is one of the main industries that provide significant development of any country because it acts as an investment industry due to the nature of its outputs. To ensure a successful construction projects, one of the important factors to be considered is managing site workers effectively. It requires good leadership qualities in handling workers’ issues. Hence, this study was aimed to develop relationship between leadership qualities and workers issues for Saudi Arabia’s construction industry. Several objectives are introduced to accomplish the aim including: identify issues engulfing site workers and also leadership qualities in Saudi Arabia’s construction industry, determine hierarchy/ranks of workers issues and leadership qualities,establish structural relationship of leadership qualities and workers’ issues, and finally develop framework of leadership qualities and workers’ issues for Saudi Arabia’s construction industry.This study was carried out using mixed mode methods or known as triangulation method that comprises of qualitative method using open-ended interviews and quantitative method using questionnaire survey. A literature review was carried out based on previous research works related to workers issues and leadership qualities and found thirty-one (31) issues and thirty-seven (37) leadership qualities. After that, qualitative exploratory study was conducted to identify the issues engulfing site workers and required leadership qualities and it involved eleven (11) construction experts. Based on the exploratory study, thirty-two (32) workers’ issues were identified and also twenty-three (23) leadership qualities were determined. Compilation of literature review results and exploratory study outcomes resulted in identifying forty-seven (47) workers’ issues and fifty-four (54) leadership qualities. Based on this process, a pilot survey involved thirty-one (31) experts working in Makkah’s construction projects was conducted using semi-structured survey to assess the level of relevancy of each identified issue and quality to Makkah’s construction industry. Outcomes of pilot survey were improved and subsequently being used in actual survey. Questionnaire survey was developed based on the outcomes of pilot survey and consisted of three parts that are respondents’ demography, identifying significant workers’ issues and identifying significant leadership qualities. Five hundred ninety (590) questionnaires were distributed manually and electronically among construction professionals in Makkah city. Only two hundred and three (203) valid responses were collected and considered vi for analysis. Collected data was used to carry out hierarchical assessments for each workers’ issue and leadership quality from most significant to less significant using univariate analysis through descriptive analysis approach. Then, the collected data were further used to establish relationships between leadership qualities with workers’ issues through multivariate analysis using SmartPLS software. Structural relationship was developed to relate leadership qualities with workers’ issues. The developed structural relationship found to be fit with Goodness of Fit (GoF) value of 0.31. Based on PLS-SEM outcomes, the framework was developed which indicates the relationship between 6 leadership qualities groups (LQ) with 4 workers’ issues group (WI). Then the developed framework was verified through interviewing 12 construction experts. Verification results confirmed that, the most appropriate leadership qualities groups that required to handle each group of workers issues are Problem Solving required for Salary Discrepancy, Agility in Actions required for Under Performance, Wisdom Approach required for Unfair Treatment and Effective Implementation required for Restricted Regulation. This study has significantly pointed out the required leadership qualities that are vital to handle workers’ issues successfully for Saudi Arabia’s construction industry. Findings can be helpful for construction players in hiring potential leaders for their organizations

Neural Substrates of Cognitive Motor Interference During Walking; Peripheral and Central Mechanisms

Current gait control models suggest that independent locomotion depends on central and peripheral mechanisms. However, less information is available on the integration of these mechanisms for adaptive walking. In this cross-sectional study, we investigated gait control mechanisms in people with Parkinson’s disease (PD) and healthy older (HO) adults: at self-selected walking speed (SSWS) and at fast walking speed (FWS). We measured effect of additional cognitive task (DT) and increased speed on prefrontal (PFC) and motor cortex (M1) activation, and Soleus H-reflex gain. Under DT-conditions we observed increased activation in PFC and M1. Whilst H-reflex gain decreased with additional cognitive load for both groups and speeds, H-reflex gain was lower in PD compared to HO while walking under ST condition at SSWS. Attentional load in PFC excites M1, which in turn increases inhibition on H-reflex activity during walking and reduces activity and sensitivity of peripheral reflex during the stance phase of gait. Importantly this effect on sensitivity was greater in HO. We have previously observed that the PFC copes with increased attentional load in young adults with no impact on peripheral reflexes and we suggest that gait instability in PD may in part be due to altered sensorimotor functioning reducing the sensitivity of peripheral reflexes

Neural substrates of cognitive motor interference during walking: Peripheral and central mechanisms

Current gait control models suggest that independent locomotion depends on central and peripheral mechanisms. However, less information is available on the integration of these mechanisms for adaptive walking. In this cross-sectional study, we investigated gait control mechanisms in people with Parkinson’s disease (PD) and healthy older (HO) adults: at self-selected walking speed (SSWS) and at fast walking speed (FWS). We measured effect of additional cognitive task (DT) and increased speed on prefrontal (PFC) and motor cortex (M1) activation, and Soleus H-reflex gain. Under DT-conditions we observed increased activation in PFC and M1. Whilst H-reflex gain decreased with additional cognitive load for both groups and speeds, H-reflex gain was lower in PD compared to HO while walking under ST condition at SSWS. Attentional load in PFC excites M1, which in turn increases inhibition on H-reflex activity during walking and reduces activity and sensitivity of peripheral reflex during the stance phase of gait. Importantly this effect on sensitivity was greater in HO. We have previously observed that the PFC copes with increased attentional load in young adults with no impact on peripheral reflexes and we suggest that gait instability in PD may in part be due to altered sensorimotor functioning reducing the sensitivity of peripheral reflexes

Associations between prefrontal cortex activation and H-reflex modulation during dual task gait

Walking, although a largely automatic process, is controlled by the cortex and the spinal cord with corrective reflexes modulated through integration of neural signals from central and peripheral inputs at supraspinal level throughout the gait cycle. In this study we used an additional cognitive task to interfere with the automatic processing during walking in order to explore the neural mechanisms involved in healthy young adults. Participants were asked to walk on a treadmill at two speeds, both with and without additional cognitive load. We evaluated the impact of speed and cognitive load by analysing activity of the pre-frontal cortex (PFC) using functional Near-Infrared Spectroscopy (fNIRS) alongside spinal cord reflex activity measured by soleus H-reflex amplitude and gait changes obtained by using an inertial measuring unit. Repeated measures ANOVA revealed that fNIRS Oxy-Hb concentrations significantly increased in the PFC with dual task (walking while performing a cognitive task) compared to a single task only (walking) (p<0.05). PFC activity was unaffected by increases of walking speed. H-reflex amplitude and gait variables did not change in response to either dual task or increases in walking speed. When walking under additional cognitive load participants adapted by using greater activity in the PFC, but this adaption did not detrimentally affect H-reflex amplitude or gait variables. Our findings suggests that in a healthy young population central mechanisms (PFC) are activated in response to cognitive loads but that H-reflex activity and gait performance can successfully be maintained. This study provides insights into the mechanisms behind healthy individuals safely performing dual task walking

A randomised controlled trial of a walking training with simultaneous cognitive demand (dual task) in chronic stroke

Objective. To evaluate the tolerability of, adherence to and efficacy of a community walking training programme with simultaneous cognitive demand (dual‐task) compared to a control walking training programme without cognitive distraction. Methods. Adult stroke survivors, at least 6 months after stroke with a visibly obvious gait abnormality or reduced two‐minute walk distance were included into a 2‐arm parallel randomized controlled trial of complex intervention with blinded assessments. Participants received a 10 week, bi‐weekly, 30 minutes treadmill program at an aerobic training intensity (55‐85% heart rate maximum), either with, or without simultaneous cognitive demands. Outcome measured at 0, 11 and 22 weeks. Primary: two‐minute‐walk tests with and without cognitive distraction, dual task effect on walking and cognition; secondary: SF‐36, EuroQol‐5D‐5L, Physical Activity Scale for Elderly (PASE), and step activity. Results. Fifty stroke patients were included, 43 received allocated training and 45 completed all assessments. The experimental group (n = 26) increased mean (SD) two‐minute walking distance from 90.7 (8.2) to 103.5 (8.2) metres, compared with 86.7 (8.5) to 92.8 (8.6) in the control group, and their PASE score from 74.3 (9.1) to 89.9 (9.4), compared with 94.7 (9.4) to 77.3 (9.9) in the control group. Statistically, only the change in the PASE differed between the groups (p = 0.029), with the dual‐task group improving more. There were no differences in other measures. Conclusions. Walking with specific additional cognitive distraction (dual‐task training) might increase activity more over 12 weeks, but the data are not conclusive

Motor learning in developmental coordination disorder: behavioral and neuroimaging study

Developmental coordination disorder (DCD) is characterized by motor learning deficits that are poorly understood within whole-body activities context. Here we present results of one of the largest non-randomized interventional trials combining brain imaging and motion capture techniques to examine motor skill acquisition and its underpinning mechanisms in adolescents with and without DCD. A total of 86 adolescents with low fitness levels (including 48 with DCD) were trained on a novel stepping task for a duration of 7 weeks. Motor performance during the stepping task was assessed under single and dual-task conditions. Concurrent cortical activation in the prefrontal cortex (PFC) was measured using functional near-infrared spectroscopy (fNIRS). Additionally, structural and functional magnetic resonance imaging (MRI) was conducted during a similar stepping task at the beginning of the trial. The results indicate that adolescents with DCD performed similarly to their peers with lower levels of fitness in the novel stepping task and demonstrated the ability to learn and improve motor performance. Both groups showed significant improvements in both tasks and under single- and dual-task conditions at post-intervention and follow-up compared to baseline. While both groups initially made more errors in the Stroop task under dual-task conditions, at follow-up, a significant difference between single- and dual-task conditions was observed only in the DCD group. Notably, differences in prefrontal activation patterns between the groups emerged at different time points and task conditions. Adolescents with DCD exhibited distinct prefrontal activation responses during the learning and performance of a motor task, particularly when complexity was increased by concurrent cognitive tasks. Furthermore, a relationship was observed between MRI brain structure and function measures and initial performance in the novel stepping task. Overall, these findings suggest that strategies that address task and environmental complexities, while simultaneously enhancing brain activity through a range of tasks, offer opportunities to increase the participation of adolescents with low fitness in physical activity and sports

Dual-task walking and automaticity after stroke: Insights from a secondary analysis and imaging sub-study of a randomised controlled trial

Objective. To test the extent to which initial walking speed influences dual-task performance after walking intervention, hypothesising that slow walking speed affects automatic gait control, limiting executive resource availability. Design. A secondary analysis of a trial of dual-task (DT) and single-task (ST) walking interventions comparing those with good (walking speed ⩾0.8 m s−1, n = 21) and limited (walking speed <0.79 m s−1, n = 24) capacity at baseline. Setting. Community. Subjects. Adults six-months post stroke with walking impairment. Interventions. Twenty sessions of 30 minutes treadmill walking over 10 weeks with (DT) or without (ST) cognitive distraction. Good and limited groups were formed regardless of intervention received. Main measures. A two-minute walk with (DT) and without (ST) a cognitive distraction assessed walking. fNIRS measured prefrontal cortex activation during treadmill walking with (DT) and without (ST) Stroop and planning tasks and an fMRI sub-study used ankle-dorsiflexion to simulate walking. Results. ST walking improved in both groups (∆baseline: Good = 8.9 ± 13.4 m, limited = 5.3±8.9 m, Group × time = P < 0.151) but only the good walkers improved DT walking (∆baseline: Good = 10.4 ± 13.9 m, limited = 1.3 ± 7.7 m, Group × time = P < 0.025). fNIRS indicated increased ispilesional prefrontal cortex activation during DT walking following intervention (P = 0.021). fMRI revealed greater DT cost activation for limited walkers, and increased resting state connectivity of contralesional M1 with cortical areas associated with conscious gait control at baseline. After the intervention, resting state connectivity between ipsilesional M1 and bilateral superior parietal lobe, involved in integrating sensory and motor signals, increased in the good walkers compared with limited walkers. Conclusion. In individuals who walk slowly it may be difficult to improve dual-task walking ability

Apical Root Resorption, Microapical Surgery Management of Root Resorption

When the apical root is removed during apical surgery, the crown-to-root ratio is altered in a manner that is not desirable. The crown-to-root ratio has been utilized for teeth that have periodontal disease. It is important to note that apical root excision is not the same as periodontal bone loss here. Microsurgery in endodontics allows for the realization of a 0 degree or shallow bevel, as well as the precise length of root excision, and it also reduces the width of the osteotomy in the longitudinal direction. For the purpose of determining the prosthodontic prognosis of the teeth that have been apically removed, the crown-to-root ratio is not an acceptable metric. For the purpose of preventing endo-perio communication, it is vital to perform endodontic microsurgery with precision in order to protect the buccal bone