• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1375
  • 302
  • 136
  • 112
  • 104
  • 83
  • 57
  • 53
  • 30
  • 26
  • 25
  • 24
  • 22
  • 16
  • 16
  • Tagged with
  • 2888
  • 813
  • 382
  • 319
  • 226
  • 199
  • 197
  • 194
  • 178
  • 173
  • 152
  • 151
  • 148
  • 139
  • 134
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
481

The development of handwriting in young children

January 2019 (has links)
archives@tulane.edu / Despite the increasing use of keyboards in the classroom, handwriting is still considered a fundamental skill that young children need to master to succeed in most areas of the elementary school curriculum. Children’s school readiness is determined by an array of cognitive, perceptual, and motor abilities that provide the foundation for academic success. These foundational abilities must be integrated for efficient handwriting and a failure of this integration predicts later academic achievement. When children begin writing, they develop from producing incoherent lines to producing letters that are more common in their language or are found in their names. Children must then learn to produce the remaining letters in their alphabet to become proficient writers. The process that children use to master the letters of an alphabet is not well understood. Previous research has focused primarily on the production of handwriting as a single skill, yet the production of handwriting entails a process in which children must integrate visual, fine motor, and basic reading skills to produce letters and words. The process of handwriting also develops in an environment that is full of letters and words. To date, the literature on handwriting has failed to address the processes that children utilize during handwriting, how these processes change through children’s development, and how the environment children are developing in influences these processes. This dissertation provides a theoretically integrative account of children’s handwriting development. The objectives of this dissertation are to determine the letter frequencies in children’s picture books, determine the opportunities that children are presented to copy letters in handwriting workbooks, measure the influence of change in grade and growth of basic reading skills on children’s visual processing development during handwriting, and measure visual-motor integration during handwriting. The approach to test these objectives is to integrate methods from educational and developmental psychology literatures in a novel series of studies using content analyses of children’s educational resources, head-mounted eye-tracking and academic assessments. By understanding the interaction between cognitive, linguistic, visual, and motor processes, researchers may establish possible mechanisms for the process of children’s development of complex skills, such as handwriting. / 1 / Nicholas E. Fears
482

The Development Of Vision And Basic Reading Skills In Handwriting

January 2016 (has links)
Handwriting is a fundamental skill that must be acquired early in education for academic success. For example, printing errors made by kindergarten children have been found to predict reading and language achievement in first grade(Simner, 1982). The dynamic interplay of perceptual, motor, and linguistic skills makes handwriting a complex skill that can be challenging for young children to master. In this study, the eye movements of 40 children between the ages of 4 and 8 years of age were analyzed to determine how efficiency in visual-motor coordination develops as they copy letters and words, methods that teachers commonly employ to teach handwriting. These data provide new information about the development of the processes involved in the complex skill of handwriting during the first years of formal education. In the early school years, children become increasingly efficient in how they deploy eye movements as they learn to copy letters. The new methods used here provide a more fine-grained assessment tool to measure visual perception during handwriting and offer a more systematic approach for identifying potential sources of errors made by young children as they learn to write. / Nicholas E Fears
483

Here's looking at you, kid! : sex differences, sex-typing, and mutual gaze behavior in young infants

Leeb, Rebecca T. January 1999 (has links)
No description available.
484

Therapeutic ocular surface medium: clinical and in vitro studies

Watson, Stephanie Louise, Prince of Wale Hospital Clinical School, UNSW January 2005 (has links)
Therapeutic Ocular Surface Medium (TOSM) is a potential new treatment for patients with ocular surface disorders such as dry eye and persistent epithelial defect (PED). New therapies are needed as many patients with dry eye and PED continue to suffer despite maximal standard therapy, and while efficacious autologous serum therapy is not routinely available. Like serum, TOSM contains tear components and was expected to have some of the physiological effects of tears. Clinical and in vitro studies were used to evaluate two similar formulations of TOSM. To comply with local pharmacy manufacturing policies, components were omitted from TOSM v1 to produce TOSM v2. In pilot studies, conducted over 1 month, TOSM v1 improved dry eye signs and symptoms and healed over a quarter of PED. In a 2 month randomised double-masked trial, TOSM v2 improved the signs and symptoms of dry eye but was not superior to saline (placebo). No serious or irreversible side-effects occurred. The altered composition of TOSM v2 may have reduced its efficacy. However, a significant improvement in blepharitis (eyelid margin disease) and conjunctival impression cytology (an objective measure of ocular surface health) was found with TOSM v2. Improvement in blepharitis is an encouraging finding as it has not been reported in other dry eye trials. It was hypothesised that TOSM would benefit ocular surface disorders by improving ocular surface health. In vitro, primary and cell line human corneal epithelial cells were supported by TOSM v1 and TOSM v2. Outgrowth from limbal explants and corneal reepithelialisation following wounding occurred with TOSM v2. This and the impression cytology findings support our hypothesis. Further, ocular surface damage with dry eye and PED may activate the corneal wound healing response. For wound healing, compared to human serum, TOSM v1 and TOSM v2 had beneficial effects in vitro on epithelial cells and human corneal fibroblasts. This may translate into a reduction in potentially vision-threatening corneal scarring in vivo with TOSM. However, ocular surface disorders are a heterogenous group and wound healing is a complex process such that different preparations of TOSM may be needed for use in different disorders and at different stages of the disease process.
485

Studies in the biology and reproductive characteristics of Pseudomugil signifer.

Howe, Effie Helena Irene January 1995 (has links)
The aims of this study were firstly to observe the breeding behaviour and embryo ology. and then to identify factors affecting the reproductive biology of the Australian native pseudomtlgilid Pseudomugil signifer (pacific blue-eye) and the impact upon it of the presence of the exotic species Gambusia holbrooki (eastern gambusia). Six species of the genus Pseudomugil, and the related Scaturiginichthys venneilipinnis, are found on the Australian continent. The normal breeding behaviour, egg surface morphology and embryology of four species of Pseudomugil (P. signijer, P. genrudae, P. tenellus and P. mellis) were first investigated, using aquarium and microscopic (light and S.E.M.) studies. The four species were divided into two groups: P. signifer and P. mellis; and P. tenellus and P. gertrudae. The study provided further evidence for the view that the embryology of the genus Pseudomugil differs markedly from that of members of the family Melanotaeniidae, with which the pseudomugilids have previously been grouped. The seasonal pattern of gonadal function in P. signifer, both in the field and in aquariums, was then investigated for populations of P. signifer from the Sydney region. It was found that P. signifer bred over the spring and summer months, commencing breeding as the temperature and daylength increased, and declining in breeding activity as daylength and temperature declined. There was no substantial difference in the pattern of reproductive activity between wild and captive stocks of P. signifer in the populations used. The impact of the presence of the introduced G. holbrooki on P. signifer was then examined, first in open-air tank experiments , and then in the field. In the tank experiments the exotic species profoundly affected the breeding of the native species. When G. holbrooki were in the tanks P. signifer did not gain weight or grow in total length (except for females given supplementary feed); ovarian weight and fecundity was greatly reduced and the ovaries were morphologically undeveloped. No eggs from P. signifer were observed in tanks which also housed G. holbrooki. G. holbrooki were observed to actively hunt and eat young P. signifer and to nip the caudal fins of adult P. signifer. The results indicate clearly, that at least in a captive situation, the presence of the exotic species has a very deleterious effect on breeding and hence possible survival, of a native population. A pilot study conducted at the same time as the harvest of the second tank study did not reveal such drastic consequences. However, even in the less confined field situation, some evidence of an interrelation between water quality, numbers of P. signifer and numbers of G. holbrooki were seen in one disturbed site (Home bush Bay). These findings suggest that a newly designed field experiment based on data collected from the power analysis of the pilot study could clarify whether G. holbrooki adversely affects P. signifer in the wild. The information gained from these studies can be used in the management of P. signifer in the wild, and serve as a model of the possible effects upon other native species.
486

Studies in the biology and reproductive characteristics of Pseudomugil signifer.

Howe, Effie Helena Irene January 1995 (has links)
The aims of this study were firstly to observe the breeding behaviour and embryo ology. and then to identify factors affecting the reproductive biology of the Australian native pseudomtlgilid Pseudomugil signifer (pacific blue-eye) and the impact upon it of the presence of the exotic species Gambusia holbrooki (eastern gambusia). Six species of the genus Pseudomugil, and the related Scaturiginichthys venneilipinnis, are found on the Australian continent. The normal breeding behaviour, egg surface morphology and embryology of four species of Pseudomugil (P. signijer, P. genrudae, P. tenellus and P. mellis) were first investigated, using aquarium and microscopic (light and S.E.M.) studies. The four species were divided into two groups: P. signifer and P. mellis; and P. tenellus and P. gertrudae. The study provided further evidence for the view that the embryology of the genus Pseudomugil differs markedly from that of members of the family Melanotaeniidae, with which the pseudomugilids have previously been grouped. The seasonal pattern of gonadal function in P. signifer, both in the field and in aquariums, was then investigated for populations of P. signifer from the Sydney region. It was found that P. signifer bred over the spring and summer months, commencing breeding as the temperature and daylength increased, and declining in breeding activity as daylength and temperature declined. There was no substantial difference in the pattern of reproductive activity between wild and captive stocks of P. signifer in the populations used. The impact of the presence of the introduced G. holbrooki on P. signifer was then examined, first in open-air tank experiments , and then in the field. In the tank experiments the exotic species profoundly affected the breeding of the native species. When G. holbrooki were in the tanks P. signifer did not gain weight or grow in total length (except for females given supplementary feed); ovarian weight and fecundity was greatly reduced and the ovaries were morphologically undeveloped. No eggs from P. signifer were observed in tanks which also housed G. holbrooki. G. holbrooki were observed to actively hunt and eat young P. signifer and to nip the caudal fins of adult P. signifer. The results indicate clearly, that at least in a captive situation, the presence of the exotic species has a very deleterious effect on breeding and hence possible survival, of a native population. A pilot study conducted at the same time as the harvest of the second tank study did not reveal such drastic consequences. However, even in the less confined field situation, some evidence of an interrelation between water quality, numbers of P. signifer and numbers of G. holbrooki were seen in one disturbed site (Home bush Bay). These findings suggest that a newly designed field experiment based on data collected from the power analysis of the pilot study could clarify whether G. holbrooki adversely affects P. signifer in the wild. The information gained from these studies can be used in the management of P. signifer in the wild, and serve as a model of the possible effects upon other native species.
487

Metabolic effects of ultraviolet radiation on the anterior part of the eye

Tessem, May-Britt January 2006 (has links)
<p>Ultraviolet radiation (UV-R) is an environmental factor known to increase the risk of developing an irreversible opacification of the lens (cataract). Increased irradiance of UV-R to the earth because of depletion of stratospheric ozone is of current concern considering cataract formation. Detailed metabolic information from the cornea, lens and aqueous humour might give valuable knowledge on the biochcemical processes occurring in the eye after exposure to UV-R, and thereby a better understanding of the mechanisms by which UV-R induces cataractogenesis. The purpose of this thesis was to study metabolic effects of exposure to UV-R on the anterior part of the eye. Effects of UV-B (280-315 nm) and UV-A (315-400 nm) on the aqueous humour, cornea and the lens from animal models were investigated by <sup>1</sup>H nuclear magnetic resonance (NMR) spectroscopy. Since the lens is composed of functionally distinct anatomical compartments, with different metabolic activity, biochemical changes in various compartments of the lens were analyzed.</p><p>Application of NMR-based metabonomics was effective to analyze metabolic changes in the anterior part of the eye after exposure to UV-R. High-resolution (HR) magic angle spinning (MAS)<sup> 1</sup>H NMR spectroscopy provided high quality spectra from intact tissue of cornea and lens, and provided important information about metabolic alteration occurring in these tissues after exposure to UV-R. The results from this thesis show that in vivo UV-B radiation affects metabolism of the anterior compartments of the eye. Metabolic changes were observed in aqueous humour, cornea, lens and in the different compartments of the lens. The antioxidants, glutathione and ascorbate, several amino acids, high energetic phosphates, and compounds important for membrane building and osmoregulation were substantially altered after exposure to UV-B radiation. Several biochemical effects such as oxidation, membrane disruption, osmoregulatory problems, lipid peroxidation, problems with cellular signalling and impairment of growth and protein synthesis were suggested. After UV-A exposure, no observable metabolic alterations were found in the anterior part of the eye in the present animal models.</p>
488

Application of high-resolution NMR spectroscopy in metabolic studies of the eye

Risa, Øystein January 2004 (has links)
<p>High-resolution NMR spectroscopy has, during the last two decades, had an increasing impact in biological and biochemical research. Rapid advances have led to improvements in sensitivity and dispersion of the spectra and have allowed more detailed assignment and monitoring of endogenous biochemical molecules. One of the latest implementations has been a technique known as high-resolution magic angle spinning (HR-MAS) NMR spectroscopy which has made it possible to obtain high-resolution proton spectra of intact tissue and cells. Simultaneous detection of a large number of metabolites by NMR spectroscopy has been successfully applied to investigate disordered metabolism for a numerous of diseases and toxic processes.</p><p>The objectives in the present work have been to evaluate different <sup>1</sup>H NMR spectroscopy protocols as analytical tools in eye research, and further use these protocols to extract and interpret information on metabolic changes in the eye induced by external pathological stimuli. Special focus has been paid to changes in the lens and the development of cataracts.</p><p>The <sup>1</sup>H NMR spectra of intact lenses and eye tissue extracts in present thesis showed an extensive picture of NMR detectable metabolites. In addition to the detailed analysis of extracts from cornea, lens and aqueous humour, this work has created a basis for implementation and interpretation of HR-MAS <sup>1</sup>H NMR spectroscopy on intact lens tissue. Several significant changes in the metabolic content in cornea, aqueous humour, and lens after alkali-burns to the eye were detected and showed how careful <sup>1</sup>H NMR spectroscopy analysis of tissue extracts provided new information (quantitative and qualitative) on the metabolic reaction pattern in the anterior eye segment in relation to eye alkali-burn injuries.</p><p>HR-MAS studies on lenses exposed <i>in vivo </i>to different ultraviolet-B doses did not reveal any dose-response relationship for the metabolic changes. However, significant concentration changes for most of the observed metabolites seven days post exposure demonstrated that closeto- threshold UVB radiation had great impact on the metabolites in the lens. Further time dependency studies of metabolic changes in rat lens after UVB radiation showed that significant changes in metabolite concentrations were subsequent to lens opacity development. Long-term steroid treatment (36 days) seemed to have greater impact on the metabolic changes compared to the UVB-induced changes 24 hours after UVB radiation. Even though no obvious cataract was detected after the combined treatment of steroids and UVB radiation, significant changes were observed for several metabolites.</p> / Paper III is reprinted with kind permission from Elsevier, sciencedirect.com
489

Stereo and Eye Movement

Geiger, Davi, Yuille, Alan 01 January 1988 (has links)
We describe a method to solve the stereo correspondence using controlled eye (or camera) movements. These eye movements essentially supply additional image frames which can be used to constrain the stereo matching. Because the eye movements are small, traditional methods of stereo with multiple frames will not work. We develop an alternative approach using a systematic analysis to define a probability distribution for the errors. Our matching strategy then matches the most probable points first, thereby reducing the ambiguity for the remaining matches. We demonstrate this algorithm with several examples.
490

Application of high-resolution NMR spectroscopy in metabolic studies of the eye

Risa, Øystein January 2004 (has links)
High-resolution NMR spectroscopy has, during the last two decades, had an increasing impact in biological and biochemical research. Rapid advances have led to improvements in sensitivity and dispersion of the spectra and have allowed more detailed assignment and monitoring of endogenous biochemical molecules. One of the latest implementations has been a technique known as high-resolution magic angle spinning (HR-MAS) NMR spectroscopy which has made it possible to obtain high-resolution proton spectra of intact tissue and cells. Simultaneous detection of a large number of metabolites by NMR spectroscopy has been successfully applied to investigate disordered metabolism for a numerous of diseases and toxic processes. The objectives in the present work have been to evaluate different 1H NMR spectroscopy protocols as analytical tools in eye research, and further use these protocols to extract and interpret information on metabolic changes in the eye induced by external pathological stimuli. Special focus has been paid to changes in the lens and the development of cataracts. The 1H NMR spectra of intact lenses and eye tissue extracts in present thesis showed an extensive picture of NMR detectable metabolites. In addition to the detailed analysis of extracts from cornea, lens and aqueous humour, this work has created a basis for implementation and interpretation of HR-MAS 1H NMR spectroscopy on intact lens tissue. Several significant changes in the metabolic content in cornea, aqueous humour, and lens after alkali-burns to the eye were detected and showed how careful 1H NMR spectroscopy analysis of tissue extracts provided new information (quantitative and qualitative) on the metabolic reaction pattern in the anterior eye segment in relation to eye alkali-burn injuries. HR-MAS studies on lenses exposed in vivo to different ultraviolet-B doses did not reveal any dose-response relationship for the metabolic changes. However, significant concentration changes for most of the observed metabolites seven days post exposure demonstrated that closeto- threshold UVB radiation had great impact on the metabolites in the lens. Further time dependency studies of metabolic changes in rat lens after UVB radiation showed that significant changes in metabolite concentrations were subsequent to lens opacity development. Long-term steroid treatment (36 days) seemed to have greater impact on the metabolic changes compared to the UVB-induced changes 24 hours after UVB radiation. Even though no obvious cataract was detected after the combined treatment of steroids and UVB radiation, significant changes were observed for several metabolites. / Paper III is reprinted with kind permission from Elsevier, sciencedirect.com

Page generated in 0.047 seconds