Excitable cells display dynamically regulated changes in the properties of ion currents during development. These changes are crucial for the proper maturation of cellular excitability, and therefore have the potential to affect more sophisticated functions, including neural circuits, movements, and behaviors. Zebrafish skeletal muscle is an excellent model for studying the development of ion channels and their contributions to excitability. They possess distinguishable populations of red and white muscle fibers, whose biological functions are well understood. The main objectives of this thesis were: (1) To characterize the development of muscle excitability by examining properties of voltage-gated sodium and potassium currents expressed in embryonic and larval zebrafish during the first week of development. (2) To elucidate some of the mechanisms by which ion current development might be controlled, beginning with activity-dependent and phosphorylation-dependent mechanisms. These objectives were approached using whole-cell electrophysiological techniques to examine the voltage-dependent and kinetic properties of voltage-gated sodium and potassium currents in intact zebrafish skeletal muscle preparations. Mutant sofa potato zebrafish, which lack functional nicotinic acetylcholine receptors, were then utilized to determine whether synaptic activity at the neuromuscular junction is required for proper ion current development. Finally, protein kinases were activated pharmacologically in order to determine whether they were able to modulate ion currents during development. The results revealed that properties of ion currents undergo a developmental progression, including increased current density, accelerated kinetics, and shifts in voltage-dependence; these developments correlated well with the maturation of muscle action potentials and the movements and behaviors they mediate. Sofa potato mutants were found to be deficient in certain aspects of ion current development, but other aspects appeared to be unaffected by a lack of synaptic activity. Protein kinase A demonstrated the ability to drastically reduce potassium current density; however the effects of PKA were similar at all developmental stages. Overall, these findings provide novel insight into the roles played by voltage-gated currents during the development of excitability in zebrafish skeletal muscle, and expand the rapidly growing body of knowledge about ion channel function in general. / Physiology, Cell & Developmental Biology

This study looks at characteristics of rental gated communities in the United States from a national perspective and based on a case study of four Southwestern Counties, Riverside County and San Bernardino County in California, Maricopa County in Arizona, and Clark County, Nevada. Tenure differences between owned and rental gated communities are compared. The study also debates who actually benefits from rental gated communities and what that effect that has upon the community. This analysis is done by assessing whether minorities experience higher housing opportunities in rental gated communities newer, fast growing areas as the study area. Descriptive statistics of rental gated community characteristics are presented and neighborhood diversity indices are analyzed. The study finds that rental gated communities are much like their owned gated community counterparts and that new housing markets do not present better housing opportunities (at the neighborhood level)for minorities, particularly those neighborhoods with more rental gated properties present. Policy implications are discussed. / Ph. D.

Diss. (sammanfattning) Linköping : Linköpings universitet, 2007. / Härtill 4 uppsatser.

External beam radiotherapy (RT) is the primary treatment modality for patients with inoperable lung tumours. Respiration-induced motion and related intra-/interfractional variations present a series of limitations to the success of existing conventional treatment modalities for lung cancer. Subsequently, to minimise the effects of respiration different management techniques have been proposed and are available. Respiratory gated radiotherapy (RGRT) holds promise to improve dose conformity, reduce the normal tissue control probability while increasing the tumour control probability. Its effectiveness depends on precise tumour localisation and targeting during dose delivery. In this thesis, the suitability of RGRT for the compensation of breathing induced motion was investigated by means of phantom studies and film dosimetry. Both regular and irregular trajectories were simulated during gated dose delivery and their effects on dose distributions analysed. Respiration-induced motion led to dose blurring and hence to less conformal dose distributions, which resulted overall in underdose of the treatment planning volume and an overdose of healthy surrounding tissue. Compared to non-gated dose delivery, RGRT improved dose conformity by enabling steeper dose gradients, resulting in an increased sparing of healthy tissue, at the expenses of increased delivery times. In the presence of irregular motion paths the dosimetric advantages of RGRT were observed to decrease. In the absence of a clinical tool for treatment verification such irregularities may pass unnoticeable and may lead to poor treatment outcomes. Investigations of the suitability of a software tool for tracking lung tumours in portal images during RGRT demonstrated that it is possible to determine and track tumour motion during gated treatment. Both the residual tumour motion inside the gating window as well as the probability density function were used as measures to quantify tumour position and variability. Tracking information was sufficient to quantify residual motion and variability. Baseline drifts as well as sudden fluctuations in tumour positions were detected and quantified, which led to considerable variations in residual motion which in turn may result in marginal miss. Although this was a retrospective analysis of motion data, the tool showed a great potential for verification of the tumour position during RGRT and may possibly be useful for adaptation of the gating window.

Hokkaido University (北海道大学) / 博士 / 医学

<p>This is an essay about gated communities and their impact on society. The key questions of my essay are: why people choose to live in gated communities; how the city is impacted by gated communities and what the difference concerning the reasons and impact of gated communities in Florida and Sweden is, and what this difference might depend on. I am using postmodern urbanism as a starting point, and I look closer on Edward J. Soja’s theories about the postmodern metropolis. The research about gated communities is almost nonexistent in Sweden, so the literature I have read and used in my essay has mostly an American perspective. For a Swedish perspective I have among other things interviewed a professor in urban planning from the Royal Institute of Technology in Stockholm.</p><p>My study shows that a search for security and a certain lifestyle are the main reasons for people to live or want to live in gated communities, both in Florida and in Sweden. However, there is a big difference in the subject between Florida and Sweden, mainly because there are only a few living areas in Sweden that can be considered as being gated communities. In Sweden a new lifestyle community called Victoria Park and is considered being a “Swedish gated community” has gotten a lot of critique in the media. This shows that gated communities are not really accepted in Sweden yet. In Florida gated communities are not considered extraordinary and you can see the negative impacts they have had on the city, like empty cities without the service that is now found inside gated communities.</p><p>Gated communities can be seen by some as a dream living situation, and for others a nightmare. Living in a private community with gates are not yet something you can do in Sweden, but the development of living areas like Victoria Park and its popularity show that maybe it won’t take long until it’s not considered as an irregularity.</p>

This is an essay about gated communities and their impact on society. The key questions of my essay are: why people choose to live in gated communities; how the city is impacted by gated communities and what the difference concerning the reasons and impact of gated communities in Florida and Sweden is, and what this difference might depend on. I am using postmodern urbanism as a starting point, and I look closer on Edward J. Soja’s theories about the postmodern metropolis. The research about gated communities is almost nonexistent in Sweden, so the literature I have read and used in my essay has mostly an American perspective. For a Swedish perspective I have among other things interviewed a professor in urban planning from the Royal Institute of Technology in Stockholm. My study shows that a search for security and a certain lifestyle are the main reasons for people to live or want to live in gated communities, both in Florida and in Sweden. However, there is a big difference in the subject between Florida and Sweden, mainly because there are only a few living areas in Sweden that can be considered as being gated communities. In Sweden a new lifestyle community called Victoria Park and is considered being a “Swedish gated community” has gotten a lot of critique in the media. This shows that gated communities are not really accepted in Sweden yet. In Florida gated communities are not considered extraordinary and you can see the negative impacts they have had on the city, like empty cities without the service that is now found inside gated communities. Gated communities can be seen by some as a dream living situation, and for others a nightmare. Living in a private community with gates are not yet something you can do in Sweden, but the development of living areas like Victoria Park and its popularity show that maybe it won’t take long until it’s not considered as an irregularity.

The primary goal of this work was to examine the role of voltage-dependent Ca2+ channels in regulating the output of larval Drosophila motoneurons functioning within an intact network. To accomplish this goal, two major aims were addressed: 1. To determine whether larval Drosophila motoneurons express voltage-dependent Ca2+ channels in their central processes, and further, to determine the genes responsible. 2. To determine the role of centrally expressed voltage-dependent Ca2+ channels in the regulation of motoneuron output as motoneurons receive behaviorally relevant input from the locomotor network. To address these goals, genetic tools available in Drosophila were used along side in situ patch clamp techniques from larval motoneurons.Using whole cell voltage-clamp techniques in situ, we have shown that two identified motoneurons, aCC and RP-2, carry voltage-dependent currents recorded from the soma. Dmca1D, the L-type like channel in Drosophila, is primarily responsible for this current. Expressing Dmca1D RNAi in aCC and RP-2, as the preparation displayed fictive bouts of locomotion, caused an increase in burst duration in both RP-2 and aCC as well as an increase in the number of action potentials fired per burst. Additionally, the afterhyperpolarization between spikes was greatly reduced and spiking became less regular. This work indicates a role for Dmca1D in the processing of synaptic information in Drosophila motoneurons aCC and RP-2.

Optical coherence tomography (OCT) has been shown to be a versatile three-dimensional imaging tool in diagnostic medicine, combining micrometre-scale resolutions with fast acquisition times. This imaging modality uses the interference between light backscattered from a sample and light that has traversed a known reference path delay to determine the scattering profile over penetration depths of up to several millimetres in tissue. A novel OCT system is presented that uses nonlinear optics to process the backscattered light in the optical domain prior to standard Fourier-domain OCT acquisition and processing. The nonlinear optical effects experienced between short light pulses are strongly intensity-dependent, occurring only significantly when the pulses are temporally and spatially overlapped. These conditions allow for the creation of a user-controlled time gate that restricts the light backscattered from the sample to a narrow (~100 micrometres) depth field of view prior to detection. When strong and weak scattering interfaces exist across the sample depth range, the signal-to-noise ratio of the weaker scattering sites can be limited by the finite detector dynamic range in Fourier-domain OCT systems. By aligning the time gate temporal delay to the backscatter from the weak interfaces of interest, a user can completely remove the strong backscattered light and enhance imaging contrast. The nonlinear effect used in the current time-gated OCT design is sum-frequency generation, which provides an additional advantage of imaging at near infrared (1280 nm) wavelengths, used for long penetration depths in tissue, while detection is performed in the visible (504 nm) with silicon-based camera technology. With the reduced depth field of view, the number of sampling points required per depth scan is also proportionately reduced, permitting faster acquisition rates for the time-gated region of interest. A complete description of the time-gated OCT system design is presented, along with proof-of-concept images demonstrating contrast enhancement and operation in a highly scattering biological medium. Based on its successful initial performance, future development of this system is expected for its eventual use in many OCT imaging applications. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2008-01-15 20:05:41.665 / This work was funded by the Natural Sciences and Engineering Research Council and the Cancer Imaging Network of Ontario, supported by Cancer Care Ontario

Uppsatsen behandlar ”gated community” ett känt fenomen i många delar av världen och börjar även växa fram i Sverige. Syftet med uppsatsen är att förstå begreppet ”gated community”. Mer specifikt undersöka och jämföra förhållandet mellan tre olika företags marknadsförings innehåll med definitionen av gated community och teorierna som tas upp i arbetet. Metoden utgörs av en grund givande intervju samt en text- och bildanalys av företagens respektive marknadsföringsmaterial. Den empiriska text- och bildanalysen är den huvudsakliga metoden som kommer att utgöra resultat i denna studie. Resultatet visar på att gated communities är en växande boendeform, även i Sverige är det fastslaget att företaget Victoria Park kommer att expanderas. Vad gäller företagens marknadsföring sker det en försköning då en fantasivärld målas upp på hemsidorna i kontrast med verkligheten. Fenomenet är en demonstration mot samhällets utveckling då medborgarna inte är nöjda med den urbana stadens hantering av trygghetsfaktorn. Detta leder till att en del av befolkningen tar saken i egna händer genom att flytta in i gated communities. Med andra ord leder detta till boendesegregering.