44,135 research outputs found
Theory of semi-ballistic wave propagation
Wave propagation through waveguides, quantum wires or films with a modest
amount of disorder is in the semi-ballistic regime when in the transversal
direction(s) almost no scattering occurs, while in the long direction(s) there
is so much scattering that the transport is diffusive. For such systems
randomness is modelled by an inhomogeneous density of point-like scatterers.
These are first considered in the second order Born approximation and then
beyond that approximation. In the latter case it is found that attractive point
scatterers in a cavity always have geometric resonances, even for Schr\"odinger
wave scattering. In the long sample limit the transport equation is solved
analytically. Various geometries are considered: waveguides, films, and
tunneling geometries such as Fabry-P\'erot interferometers and double barrier
quantum wells. The predictions are compared with new and existing numerical
data and with experiment. The agreement is quite satisfactory.Comment: 24 pages Revtex; 10 figure
Sociological Knowledge and Transformation at âDiversity Universityâ, UK
This chapter is based on a case study of one UK university sociology department and shows how sociology knowledge can transform the lives of ânon-traditionalâ students. The research from which the case is drawn focused on four departments teaching sociology-related subjects in universities positioned differently in UK league tables. It explored the question of the relationship between university reputation, pedagogic quality and curriculum knowledge, challenging taken-for-granted judgements about âqualityâ and in conceptualising âjustâ university pedagogy by taking Basil Bernsteinâs ideas about how âpowerfulâ knowledge is distributed in society to illuminate pedagogy and curriculum. The project took the view that âpowerâ lies in the acquisition of specific (inter)disciplinary knowledges which allows the formation of disciplinary identities by way of developing the means to think about and act in the world in specific ways. We chose to focus on sociology because (1) university sociology is taken up by all socio-economic classes in the UK and is increasingly taught in courses in which the discipline is applied to practice; (2) it is a discipline that historically pursues social and moral ambition which assists exploration of the contribution of pedagogic quality to individuals and society beyond economic goals; (3) the researchers teach and research sociology or sociology of education - an understanding of the subjects under discussion is essential to make judgements about quality. âDiversityâ was one of four case study universities. It ranks low in university league tables; is located in a large, multi-cultural English inner city; and, its students are likely to come from lower socio-economic and/or ethnic minority groups, as well as being the first in their families to attend university. To make a case for transformative teaching at Diversity, the chapter draws on longitudinal interviews with students, interviews with tutors, curriculum documents, recordings of teaching, examples of student work, and a survey. It establishes what we can learn from the case of sociology at Diversity, arguing that equality, quality and transformation for individuals and society are served by a university curriculum which is research led and challenging combined with pedagogical practices which give access to difficult-to-acquire and powerful knowledge
Lie groups of conformal motions acting on null orbits
Space-times admitting a 3-dimensional Lie group of conformal motions
acting on null orbits are studied. Coordinate expressions for the metric and
the conformal Killing vectors (CKV) are provided (irrespectively of the matter
content) and then all possible perfect fluid solutions are found, although none
of these verify the weak and dominant energy conditions over the whole
space-time manifold.Comment: 5 pages, Late
Health and cancer prevention: knowledge and beliefs of children and young people
Objective: To collect information from children and young people about their knowledge of and attitudes towards cancer and their understanding of health and health related behaviours to inform future health promotion work. Design: Questionnaire survey of 15-16 year olds, and interviews with play materials with 9-10 year old children. Setting: Six inner city, suburban, and rural schools. Subjects: 226 children aged 15-16 years and 100 aged 9-10 years. Main outcome measures: Knowledge about different types of cancer; beliefs about health; sources of information; quality of research data obtainable from young children about cancer and health. Results: Both samples knew most about lung cancer, but there was also some knowledge of breast and skin cancer and leukaemia. Smoking, together with pollution and other environmental factors, were seen as the dominant causes of cancer. Environmental factors were mentioned more often by the inner city samples. Television and the media were the most important sources of information. Young people were more worried about unemployment than about ill health. More than half the young people did not describe their health as good, and most said they did not have a healthy lifestyle. Children were able to provide detailed information about their knowledge and understanding by using drawings as well as interviews. Conclusions: Children and young people possess considerable knowledge about cancer, especially about lung cancer and smoking, and show considerable awareness of predominant health education messages. Despite this knowledge, many lead less than healthy lifestyles. Health is not seen as the most important goal in life by many young people; the circumstances in which many children and young people live are not experienced as health promoting
Health outcomes of children born to mothers with chronic kidney disease: a pilot study
This study aimed to study the health of children born to mothers with chronic kidney disease. Twenty-four children born to mothers with chronic kidney disease were compared with 39 matched control children born to healthy mothers without kidney disease. The well-being of each child was individually assessed in terms of physical health, neurodevelopment and psychological health. Families participating with renal disease were more likely to be from lower socio-economic backgrounds. Significantly fewer vaginal deliveries were reported for mothers with renal disease and their infants were more likely to experience neonatal morbidity. Study and control children were comparable for growth parameters and neurodevelopment as assessed by the Griffiths scales. There was no evidence of more stress amongst mothers with renal disease or of impaired bonding between mother and child when compared to controls. However, there was evidence of greater externalizing behavioral problems in the group of children born to mothers with renal disease. Engaging families in such studies is challenging. Nonetheless, families who participated appreciated being asked. The children were apparently healthy but there was evidence in this small study of significant antenatal and perinatal morbidity compared to controls. Future larger multi-center studies are required to confirm these early findings
Functional and Neural Mechanisms of Out-of-Body Experiences: Importance of Retinogeniculo-Cortical Oscillations
Current research on the various forms of autoscopic phenomena addresses the clinical and neurological correlates of out-of-body experiences, autoscopic hallucinations,and heautoscopy. Yet most of this research is based on functional magnetic resonance imaging results and focuses predominantly on abnormal cortical activity. Previously we proposed that visual consciousness resulted from the dynamic retinogeniculo-cortical oscillations, such that the photoreceptors dynamically integrated with
visual and other vision-associated cortices, and was theorized to be mapped out by photoreceptor discs and rich retinal networks which synchronized with the retinotopic mapping and the associated cortex. The feedback from neural input that is received from the thalamus and cortex via retinogeniculo-cortical oscillations and sent to the retina is multifold higher than feed-forward input to the cortex. This can effectively translate into out-of-body experiences projected onto the screen formed by the retina as it is perceived via feedback and feed-forward oscillations from the reticular thalamic nucleus, or âinternal searchlightâ. This article explores the role of the reticular thalamic nucleus and the retinogeniculo-cortical oscillations as pivotal internal components in vision and various autoscopic phenomena
Meditation Experiences, Self, and Boundaries of Consciousness
Our experiences with the external world are possible mainly through vision,
hearing, taste, touch, and smell providing us a sense of reality. How the brain is able to seamlessly integrate stimuli from our external and internal world into our sense of reality has yet to be adequately explained in the literature. We have previously proposed a three-dimensional unified model of consciousness that partly explains the dynamic mechanism. Here we further expand our model and include illustrations to provide a better conception of the ill-defined space within the self, providing insight into a unified mind-body concept. In this article, we propose that our senses âsuper-imposeâ on an existing dynamic space within us after a slight, imperceptible delay. The existing space includes the entire intrapersonal space and can also be called the âthe bodyâs internal 3D default spaceâ. We provide examples from meditation experiences to help explain how the sense of âselfâ can be experienced through meditation practice associated with underlying physiological processes that take place through cardio-respiratory
synchronization and coherence that is developed among areas of the brain.
Meditation practice can help keep the body in a parasympathetic dominant state during meditation, allowing an experience of inner âselfâ. Understanding this physical and functional space could help unlock the mysteries of the function of memory and cognition, allowing clinicians to better recognize and treat disorders of the mind by recommending proven techniques to reduce stress as an adjunct to medication treatment
The Dynamic Role of Breathing and Cellular Membrane Potentials in the Experience of Consciousness
Understanding the mechanics of consciousness remains one of the most important challenges in modern cognitive science. One key step toward understanding consciousness is to associate unconscious physiological processes with subjective experiences of sensory, motor, and emotional contents. This article explores the role of various cellular membrane potential differences and how they give rise to the dynamic infrastructure of conscious experience. This article explains that consciousness is a body-wide, biological process not limited to individual organs because the mind and body are unified as one entity; therefore, no single location of consciousness can be pinpointed. Consciousness exists throughout the entire body, and unified consciousness is experienced and maintained through dynamic repolarization during inhalation and expiration. Extant knowledge is reviewed to provide insight into how differences in cellular membrane potential play a vital role in the triggering of neural and non-neural oscillations. The role of dynamic cellular membrane
potentials in the activity of the central nervous system, peripheral nervous system, cardiorespiratory system, and various other tissues (such as muscles and sensory organs) in the physiology of consciousness is also explored. Inspiration and expiration are accompanied by oscillating membrane potentials throughout all cells and play a vital role in subconscious human perception of feelings and states of mind. In addition, the role of the brainstem, hypothalamus, and complete nervous system (central, peripheral, and autonomic)within the mind-body space combine to allow consciousness to emerge and to come alive. This concept departs from the notion that the brain is the only organ that gives rise to consciousness
- âŠ