Early childhood—a period of development that research has established as a critical period for establishing a foundation to support later development and well-being—is increasingly likely to take place in multiple contexts. Continuity and discontinuity in children’s exposure to environmental chaos across two important contexts for their early development: (1) the home and (2) the early learning and care (ELC) setting were examined using data from a large representative sample of low-income preschool children attending Head Start in order to determine how children’s exposure to chaos in each context combine to either promote or interfere with their social-emotional and cognitive development over a year of preschool. A series of multi-level models tested whether children’s experiences of chaos, operationalized in three ways: (1) as individual indicators of crowding, lack of routines, and instability in each setting; (2) as a cumulative index of chaos in each setting; and (3) as a profile that incorporated children’s experiences across setting, influenced children’s social-emotional and cognitive development. Both household and classroom chaos predicted children’s development, but children’s experiences in their home environments were the predominant influence, indicating that children who had non-chaotic home environments gained more over the preschool year than did children who had chaotic homes. These findings provide additional support that effective and high-quality early education and care settings must incorporate children’s home and family experiences. / text

published_or_final_version / Surgery / Master / Master of Philosophy

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The prevalence of injuries sustained from blast have been increasing over the past few decades due to the increasing use of Improvised Explosive Devices in areas where peacekeepers are deployed, as well as terrorist bombing incidents. The scope of this project was to evaluate the potential for head injury from primary effects in blast environments and to investigate protective aspects of protective equipment and new potential protective designs to mitigate or reduce the likelihood of Traumatic Brain Injury (TBI). In order to meet these goals, methods of blast loading as well as the kinematic response of the head when subjected to blast loading were investigated numerically and validated against experimental data. This was done for both low and mid heights of burst at varying standoff distances. The methods of loading considered were the basic spherical air burst formulation of the CONventional WEaPons algorithm (CONWEP), an advanced version of the algorithm that included ground reflection and mach stem formation, and a hemispherical surface burst which included ground reflection. The method that produced the most consistent results compared to the experiments was the enhanced version of CONWEP for mid level heights of burst; however, for low heights of burst, a novel “mirrored charge” setup provided the most accurate predictions. The kinematic response of the GEBOD numerical human body model, a rigid body representation of a 50th percentile male, was validated against experimental tests conducted by Defense Research and Development Canada (DRDC) for a range of standoff distances and Heights of Burst. It was found the response of the GEBOD was in good agreement with the DRDC experiments for peak acceleration, impulse and the Head Injury Criterion. The kinematic response of the head was investigated for various charge locations to study the effects of height of burst, lateral distance and standoff distance to the charge using the GEBOD numerical human body model. It was found that the standoff and height of burst had the largest influence on the acceleration experienced by the head. The height of burst study showed a large jump in the HIC15 injury criterion and head acceleration values when the charge was detonated within the region where a mach stem would form. As would be expected for the standoff distance from the charge, the closer the charge was to the body, the higher the accelerations experienced. A quasi two dimensional model of the human head at the mid-sagittal plane was developed in order to evaluate response at the tissue level, and the effect of protection. The sagittal head model was used to examine wave interactions in the fluid flow around the head during a blast event. This was achieved by utilizing an Arbitrary Langrangian-Eulerian formulation to model the blast loading. This model was also validated against experimental data such that it demonstrated the same kinematic response as the experimental tests under identical blast loading conditions. A helmet model was coupled to the sagittal head model using a layer of foam, and a statistical study was performed to determine the main effects and any interaction effects for the parameters of the numerical foam model. By analyzing these parameters and combining the best values for the effects, an optimum foam model was determined. This foam model was compared to actual foam materials and aluminum foam was found to have the closest properties to the idealized model. The aluminum foam material model was placed into the existing sagittal model and was found to have decreased the acceleration seen by the head under all the different loading cases considered. The maximum principal strain in the brain and the maximum intracranial pressure were also examined and compared to proposed injury criterion. For implementation in a helmet, an additional layer of comfort foam or some other soft material would have to be added between the head and the aluminum foam to prevent it from cutting or injuring the person. Some of the polymeric foams investigated could be used instead of aluminum foam; however, more data is required to properly define the material response at high strain rate loading. This study has shown that blast loading to the head can result in significant accelerations which could result in injury. By using common materials in the existing form of head protection, this potential for injury can be reduced.

The representation of ourselves and our environment is based on the combination of information from multiple sensory systems. Each sensory modality is represented within a different frame of reference, in other words each sensory system uses a different code to represent the same properties of the environment (ex. visual stimuli in an eye-centered frame of reference; hand position would be shoulder-centered). Combing this information into a singular coordinate frame is complex. For instance, the eye and shoulder have different centers of rotation, therefore any changes in eye position or body posture will affect the relationship between them. What is still unknown is how the brain integrates these different sources of information into an internal representation, and what effect extra-retinal signals can have on this process. This thesis was designed to investigate the effect of head roll on action and perception. In Experiment 1, we wanted to determine how the integration of vision and proprioception for action was affected by changes in head roll. To investigate this question subjects performed a reaching task at three different head roll positions, where they would experience conflicts between their viewed and actual hand position. In Experiment 2, we examined the influence of head roll on sensory perception. To explore this idea subjects performed a task where they needed to judge the position of their unseen index fingertip relative to a visual target. Our findings reveal that eccentric head roll conditions influence both action and perception – revealed by an increase in movement variability and a decreased ability to discriminate the position of the unseen fingertip relative to visual targets. In summary, we have discovered that introducing eccentric head roll positions affects the perception of ourselves within the environment and the way that we integrate sensory information. / Thesis (Master, Neuroscience Studies) -- Queen's University, 2010-09-21 14:07:09.217

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Bessie Head's fiction reflects the author's consciousness of power as the definitive force in the South African context. By considering Head as a social realist, the thesis relates sociological evidence to authorial interest and demonstrates Head's treatment of the power issue in her three novels, When Rain Clouds Gather, Maru, and A Question of Power. Biographical data, particularly Head's unique, though socially marginal position as a political exile, a Coloured, and a woman are also applied. The thesis covers three areas--politics, race, and gender. The first explores the nature of power in South African politics within the time-frame of the present, past, and future. The second which focuses on the institution of apartheid examines racial relations between the blacks and whites and also among the blacks, with attention given to the dilemma of the Coloured. The third section discusses sexual politics, looking at male-female relationships in both traditional and contemporary societies.

Head injuries are very common in daily life and in war field. Head injuries are classified into open and closed. The mechanical mechanisms involved in closed head injuries are very different from those in open head injuries. Closed head injuries are more often re-ported with the use of protective device such as helmets. Helmets were found effective in reducing open head injuries, but less effective for closed head injuries. Finite element modeling is an effective and efficient tool for investigating head injuries. In this thesis, a two-dimensional finite element model was constructed based on a Mag-netic Resonance Image (MRI) scan data from a patient. MATLAB programming was used to extract the information from the MRI scan data. The finite element model was then used to investigate factors affecting closed head injuries. As a new contribution to closed head injury study, the fluid component in the human head, CSF, was studied by a group of comparative simulations. The other three factors, elasticity modulus of the cra-nium, contact area of impact, and impact duration were also investigated. Their effects on reducing the strain values in the brain were measured. Investigation results show that, increasing elasticity modulus of the cranium, contact area of impact and impact duration are very helpful to reduce the strain values in the brain. Helmet is helpful to protect people from closed head injuries because it can change all these three factors by using different shell stiffness and different padding material. The cerebrospinal fluid is effective in protecting the brain from impacts, as a fluid is able to reduce normal strains and filter nearly all shear strains transferred to the brain. It indicates that if a layer of fluid could be added as a layer in a protective helmet, the helmet would be more effective in protecting the brain. Conclusions obtained from the investigations are helpful for preventing closed head injuries and for improving design of protective devices such as helmets.

The goal of this exploratory research project is to gather data on head teachers’ leadership perceptions and practices, so that educational researchers, government officials and head teachers themselves have a better understanding of leadership and management in Bangladeshi high schools. Such data is critical for gaining a better understanding of leadership in Bangladesh and for future head teacher development and school improvement. Leaders can play a very important role in improving teaching and learning in schools. Many Western countries are interested in the power of leadership to generate and sustain school improvement. Bangladeshi schools strive to improve, to develop effective teaching and raise the achievement of students. Much depends on the vision and practices of the head teachers who lead the schools. This study explores the leadership concepts, styles, trends and current practices of the head teachers in four Bangladeshi private secondary schools both in rural and urban areas. Findings of this study show that Bangladeshi school leaders have vision for school improvement. They lead their schools with managerial and democratic styles of leadership. They work for professional development inside the school with a view to improve the teaching and learning process. Students’ achievement is their ultimate goal. They work under pressure with their skill of handling different kinds of adverse situation like bureaucratic complex, political influence, and shortage of human and physical resources. The methodology of this research is qualitative and the methods used for data gathering were interviews and focus group discussions. Four schools from Sirajganj, a district which is approximately one hundred kilometres away from the capital city, provided the sample. Four head teachers participated in interviews and were invited to meet together to take part in a focus group discussion about their leadership practices.

The varied impact parameters that characterize an impact to the head have shown to influence the resulting type and severity of outcome injury, both in terms of the dynamic response, and the corresponding deformation of neural tissue. Therefore, when determining head injury risks through event reconstruction, it is important to understand how individual impact characteristics influence these responses. The effect of inbound mass had not yet been documented in the literature. The purpose of this study was to determine the effects of inbound mass on the dynamic impact response and brain tissue deformation. A 50th percentile Hybrid III adult male head form was impacted using a simple pendulum system. Impacts to a centric and a non-centric impact location were performed with six varied inbound masses at a velocity of 4.0 m/s. The peak linear and peak angular accelerations were measured. A finite element model, (UCDBTM) was used to determine brain deformation, namely peak maximum principal strain and peak von Mises stress. Inbound mass produced significant differences for peak linear acceleration for centric (F(5, 24) = 217.55, p=.0005) and non-centric (F(5, 24) = 161.98, p=.0005), and for peak angular acceleration for centric (F(5, 24) = 52.51, p=.0005) and non-centric (F(5, 24) = 4.18, p=.007) impact locations. A change in inbound mass also had a significant effect on peak maximum principal strain for centric (F(5, 24) = 11.04, p=.0005) and non-centric (F(5, 24) = 5.87, p =.001), and for peak von Mises stress for centric (F(5, 24) = 24.01, p=.0005) and non-centric (F(5, 24) = 4.62, p=.004) impact locations. These results indicate the inbound mass of an impact should be of consideration when determining risks and prevention to head and brain injury.