Theory Of Spin Waves In Heisenberg Ferromagnetic And Antiferromagnetic Thin Films With Nonuniaxial Single-ion Anisotropy

This thesis describes the microscopic, quantum mechanical theory of exchange-dominated spin waves in Heisenberg ferromagnetic and antiferromagnetic thin films including the effects of nonuniaxial single-ion anisotropy. The results constitute a generalization of previous theoretical studies on spin waves in thin films with uniaxial anisotropy and in semi-infinite ferromagnets with nonuniaxial anisotropy.;A spin Hamiltonian containing nearest-neighbour exchange terms, Zeeman terms, and single-ion anisotropy terms is used. The films may be asymmetric with respect to surface exchange and anisotropy parameters which are also assured to be perturbed from the bulk values. The results apply both to cases in which the nonuniaxial anisotropy is an intrinsic aspect of the material and where it arises only at the surfaces as a consequence of lowered symmetry for those sites. Low temperatures are assumed where the linear spin-wave approximation is valid. The formalism is developed for arbitrary film thickness, arbitrary quantum spin number S, and perpendicular magnetization. Simple cubic (001) ferromagnetic systems and body-centered tetragonal (001) antiferromagnetic systems are specifically examined with extensions to other situations outlined.;A theoretical approach based on the equation-of-motion method is used to find Green functions which provide expressions for the dispersion relations for surface and quantized bulk spin waves, the associated spectral intensities, transverse spin correlation functions, and the dynamic response of the system in, for example, light scattering and spin wave resonance experiments. Representative numerical examples are provided for the dispersion relation results, some thermodynamic properties related to the mean-squared amplitude and ellipticity of spin precession, and the static magnetization. The use of the Green function results in calculating the light scattering cross-sections and absorption strength in spin wave resonance is outlined. Procedures developed to manage the increased mathematical complication associated with the nonuniaxial anisotropy are described

Foundations and Frontiers of Physics Education Research 2009

This project is a conference on the Foundations and Frontiers of Physics Education Research, in which established and up-and-coming researchers attend a residential conference to further the work of the field. There are 60 participants, including senior graduate students, research scientists, junior, and tenured faculty. The conference consists of a series of plenary talks by leaders in the community; working groups of participants to address common problems in the field and present recommendations for future work; and targeted sessions in which research topics are explored in detail by participants. Ample free time is also included, allowing for informal discussions and interactions that can lead to future collaborations. Intellectual Merit: By bringing together the leaders of the physics education research community in an intimate setting, the conference promotes more intense discussions and more focused interactions than are possible at other meetings common to the community. Broader Impact: Establishing a more cohesive research community furthers the field of physics education research. Promoting the highest quality postdoctoral researchers and junior faculty strengthens their reputation in the community, supporting the growth of new leaders. Sharing results through plenary and targeted sessions spreads knowledge that advances the field. Finally, working groups answer questions of structural concern to the physics education research community. The results of the working groups are to be published in an American Physical Society Forum on Education newsletter, allowing them to be shared with a much larger audience than attends the meeting

An investigation of the neuroprotective effects of estrogen in a model of quinolinic acid-induced neurodegeneration

The hippocampus, located in the medial temporal lobe, is an important region of the brain responsible for the formation of memory. Thus, any agent that induces stress in this area has detrimental effects and could lead to various types of dementia. Such agents include the neurotoxin, Quinolinic acid. Quinolinic acid (QUIN) is a neurotoxic metabolite of the tryptophan-kynurenine pathway and is an endogenous glutamate agonist that selectively injures and kills vulnerable neurons via the activation of the NMDA class of excitatory amino acid receptors. Estrogen is a female hormone that is responsible for reproduction. However, in the last decade estrogen has been shown to exhibit a wide range of actions on the brain, including neuroprotection. Estrogen has been shown to exhibit intrinsic antioxidant activity and protects cultured neurons against oxidative cell death. This is achieved by estrogen’s ability to scavenge free radicals, which is dependent on the presence of the hydroxyl group at the C3 position on the A ring of the steroid molecule. Numerous studies have shown that estrogen protects neurons against various toxic substances and may play a role in delaying the onset of neurodegenerative diseases, such as Alzheimer’s disease. Neuronal damage due to oxidative stress has been implicated in several neurodegenerative disorders. The detection and measurement of lipid peroxidation is the evidence most frequently cited to support the involvement of free radical reactions in toxicology and in human disease. The study aims to elucidate and further characterise the mechanism behind estrogen’s neuroprotection, using QUIN as a model of neurotoxicity. Initial studies confirm estrogen’s ability to scavenge potent free radicals. In addition, the results show that estrogen forms an interaction with iron (II) and also acts at the NMDA receptor as an agonist. Both mechanisms reduce the ability of QUIN to cause damage to neurons, since QUIN-induced toxicity is dependent on the activation of the NMDA receptor and the formation of a complex with iron (II) to induce lipid peroxidation. Heat shock proteins, especially Hsp 70 play a role in cytoprotection by capturing denatured proteins and facilitating the refolding of these proteins once the stress has been relieved. Estrogen has been shown to increase the level of expression of Hsp70, both inducible and cognate forms of the protein. This suggests that estrogen helps to protect against cellular protein damage induced by any form of stress the cell may encounter. The discovery of neuroprotective agents, such as estrogen, is becoming important as accumulating evidence indicates a protective role in vivo. Thus further research may favour the use of these agents in the treatment of several neurodegenerative disorders. Considering how devastating diseases, such as Alzheimer’s disease, are to a patient and the patient’s families, the discovery of new protective agents are a matter of urgency

Molecular Events in the Cell Types of the Olfactory Epithelium during Adult Neurogenesis

BACKGROUND: Adult neurogenesis, fundamental for cellular homeostasis in the mammalian olfactory epithelium, requires major shifts in gene expression to produce mature olfactory sensory neurons (OSNs) from multipotent progenitor cells. To understand these dynamic events requires identifying not only the genes involved but also the cell types that express each gene. Only then can the interrelationships of the encoded proteins reveal the sequences of molecular events that control the plasticity of the adult olfactory epithelium. RESULTS: Of 4,057 differentially abundant mRNAs at 5 days after lesion-induced OSN replacement in adult mice, 2,334 were decreased mRNAs expressed by mature OSNs. Of the 1,723 increased mRNAs, many were expressed by cell types other than OSNs and encoded proteins involved in cell proliferation and transcriptional regulation, consistent with increased basal cell proliferation. Others encoded fatty acid metabolism and lysosomal proteins expressed by infiltrating macrophages that help scavenge debris from the apoptosis of mature OSNs. The mRNAs of immature OSNs behaved dichotomously, increasing if they supported early events in OSN differentiation (axon initiation, vesicular trafficking, cytoskeletal organization and focal adhesions) but decreasing if they supported homeostatic processes that carry over into mature OSNs (energy production, axon maintenance and protein catabolism). The complexity of shifts in gene expression responsible for converting basal cells into neurons was evident in the increased abundance of 203 transcriptional regulators expressed by basal cells and immature OSNs. CONCLUSIONS: Many of the molecular changes evoked during adult neurogenesis can now be ascribed to specific cellular events in the OSN cell lineage, thereby defining new stages in the development of these neurons. Most notably, the patterns of gene expression in immature OSNs changed in a characteristic fashion as these neurons differentiated. Initial patterns were consistent with the transition into a neuronal morphology (neuritogenesis) and later patterns with neuronal homeostasis. Overall, gene expression patterns during adult olfactory neurogenesis showed substantial similarity to those of embryonic brain

Student Understanding of Control of Variables: Deciding Whether or Not a Variable Influences the Behavior of a System

The ability of adult students to reason on the basis of the control of variables was the subject of an extended investigation. This paper describes the part of the study that focused on the reasoning required to decide whether or not a given variable influences the behavior of a system. The participants were undergraduates taking introductory Physics and K-8 teachers studying physics and physical science in inservice institutes and workshops. Although most of the students recognized the need to control variables, many had significant difficulty with the underlying reasoning. The results indicate serious shortcomings in the preparation of future scientists and in the education of a scientifically literate citizenry. There are also strong implications for the professional development of teachers, many of whom are expected to teach control of variables to young students

A CAPACIDADE PROCESSUAL DOS ANIMAIS NO BRASIL E NA AMÉRICA LATINA

This review essay uses the logical-systematic method to analyze the standing for animals, considered in a broad sense, in Brazil and Latin America. Initially, the essay presents the main precedents of Latin American courts, which recognize animals as subjects of law and with the capacity to defend their own interests in court. Then, it reviews the concept of standing in brazilian law, in its triple configuration. Then, it analyzes Federal Decree 24.645/1934 to demonstrate that the animals have the standing, as long as they are properly assisted by their legal substitutes, by protective societies or by the public attorney. Finally, after verifying the doctrinal omission on the subject, it analyzes the advantages and disadvantages of attributing the standing for the animals.Este artículo de revisión utiliza el método lógico-sistemático para analizar la capacidad procesal de los animales, considerado en un sentido amplio, en Brasil y América Latina. Inicialmente, el artículo presenta los principales precedentes de los tribunales latinoamericanos, que reconocen a los animales como sujetos de derecho y con la capacidad de defender sus propios intereses en los tribunales. Luego, revisa el concepto de capacidad procesal en el derecho brasileño, en su configuración tríplice. Luego, analiza el Decreto federal 24.645/1934 para demostrar que los animales tienen la capacidad de ser parte procesal, siempre que estén debidamente asistidos por sus sustitutos legales, por sociedades protectoras o por el Ministerio Público. Finalmente, después de verificar la omisión doctrinal sobre el tema, analiza las ventajas y desventajas de atribuir la capacidad de ser parte de los animales.O presente artigo de revisão utiliza o método lógico-sistemático para analisar a capacidade processual dos animais, considerada em sentido amplo, no Brasil e na América Latina. Inicialmente, o artigo apresenta os principais precedentes dos tribunais latino-americanos, que reconhecem os animais como sujeitos de direito e com capacidade de defender em juízo interesses próprios. Em seguida, revisa o conceito de capacidade processual no Direito brasileiro, em sua tríplice configuração. Na sequência, analisa o Decreto federal 24.645/1934 para demonstrar que os animais possuem capacidade de ser parte processual, desde que devidamente assistidos por seus substitutos legais, pelas sociedades protetoras ou pelo Ministério Público. Por fim, após constatar a omissão doutrinária sobre o tema, analisa as vantagens e desvantagens em se atribuir capacidade de ser parte aos animais

Molecular events in the cell types of the olfactory epithelium during adult neurogenesis

BACKGROUND: Adult neurogenesis, fundamental for cellular homeostasis in the mammalian olfactory epithelium, requires major shifts in gene expression to produce mature olfactory sensory neurons (OSNs) from multipotent progenitor cells. To understand these dynamic events requires identifying not only the genes involved but also the cell types that express each gene. Only then can the interrelationships of the encoded proteins reveal the sequences of molecular events that control the plasticity of the adult olfactory epithelium. RESULTS: Of 4,057 differentially abundant mRNAs at 5 days after lesion-induced OSN replacement in adult mice, 2,334 were decreased mRNAs expressed by mature OSNs. Of the 1,723 increased mRNAs, many were expressed by cell types other than OSNs and encoded proteins involved in cell proliferation and transcriptional regulation, consistent with increased basal cell proliferation. Others encoded fatty acid metabolism and lysosomal proteins expressed by infiltrating macrophages that help scavenge debris from the apoptosis of mature OSNs. The mRNAs of immature OSNs behaved dichotomously, increasing if they supported early events in OSN differentiation (axon initiation, vesicular trafficking, cytoskeletal organization and focal adhesions) but decreasing if they supported homeostatic processes that carry over into mature OSNs (energy production, axon maintenance and protein catabolism). The complexity of shifts in gene expression responsible for converting basal cells into neurons was evident in the increased abundance of 203 transcriptional regulators expressed by basal cells and immature OSNs. CONCLUSIONS: Many of the molecular changes evoked during adult neurogenesis can now be ascribed to specific cellular events in the OSN cell lineage, thereby defining new stages in the development of these neurons. Most notably, the patterns of gene expression in immature OSNs changed in a characteristic fashion as these neurons differentiated. Initial patterns were consistent with the transition into a neuronal morphology (neuritogenesis) and later patterns with neuronal homeostasis. Overall, gene expression patterns during adult olfactory neurogenesis showed substantial similarity to those of embryonic brain

A Comprehensive Residency Wellness Curriculum

Introduction: Resident physician burnout is an epidemic in medical education. There are several wellness curricula published, but few describe a comprehensive program to address wellness. Our objectives were to develop and pilot a longitudinal resident wellness curriculum and assess for feasibility and sustainability. Methods: We surveyed emergency medicine (EM) residents from two residency programs in the United States to assess a baseline level of burnout using the Maslach Burnout Inventory. We developed a comprehensive and longitudinal wellness curriculum for EM residents that incorporated all domains identified by the American College of Emergency Physicians Wellness Wheel. Mindfulness practice was incorporated throughout the curriculum. Results: A convenience sample of 106 EM residents were sent the baseline survey. A response rate of 69% was achieved, the median age of the respondents was 29 years, and 44.5% were female. Overall, 67.5% (95% CI: 50.5; 80.8%) reported burnout in at least one of the three domains of the Maslach Burnout inventory. 34.8% reported burnout in the personal accomplishment domain, 40.8% reported depersonalization, and 44.3% reported emotional exhaustion. The wellness curriculum was successfully implemented at the Georgia-based residency program. The curriculum has proven to be sustainable since it began in 2016. Quantitative statistical testing for the post-intervention survey was not possible due to a low response rate. However, subjective receivability was high, with participants describing these sessions as high-yield, informative and practical. Conclusions: Burnout is highly prevalent among EM residents. We provide a curriculum developed for an EM residency program that is multifaceted and comprehensive, including basic wellness topics, mindfulness, financial and medicolegal issues, as well as topics that address the stresses specific to clinical emergency medicine. The curriculum has been in place in its current form since 2016 and has proven to be sustainable

SafeSpot:An innovative app and mental health support package for Scottish schools - a qualitative analysis as part of a mixed methods study

Aims: The aim of the study was to investigate teachers’ and pupils’ perceptions about the effect of the SafeSpot mental health curriculum on the well‐being of young people and on their knowledge of mental health conditions. This trial intends to determine the acceptability and benefits of web and mobile technology in delivering emotional well‐being in schools, through use of the SafeSpot programme. Background: With 10% of young people aged 5 to 16 diagnosed with a mental disorder, there is pressure for schools to address their pupils’ emotional well‐being. However, many educators report that their schools have insufficient provisions and feel inadequately equipped to support pupils’ mental health. Methods: This qualitative analysis was embedded within a randomly allocated stepped‐wedge design, conducted in six West of Scotland secondary schools. A total of 2320 pupils (aged 11 to 14 years) and 90 teachers were included. Young people’s understanding of health‐seeking, and teacher’s confidence in delivering and accessing well‐being information was assessed qualitatively. Results: Qualitative analysis revealed themes highlighting the beneficial nature of SafeSpot, including pupil engagement, content of tutorials, perceived impact of SafeSpot and level of training provided for teachers. Conclusions: Web technology could potentially offer a more structured way for staff to support their pupils’ mental health, whilst reducing stigma. SafeSpot was perceived, by pupils and teachers, to be engaging