Natural Killer (NK) cells are cytotoxic lymphocytes that can recognize and kill virally infected or tumour transformed cells by the secretion of cytolytic granules containing perforin. An individual NK cell can kill several target cells sequentially. Each target cell can trigger NK cell activation via different activating ligands and here we report that the order in which ligands are encountered affects the NK cell response. When NK cells are repeatedly activated via their Fc receptor CD16, with the therapeutic antibody rituximab, perforin secretion decreases with each stimulation. However, perforin secretion is restored to its initial level upon subsequent activation by MICA, which ligates NKG2D. Repeated stimulation of NK cells via MICA also decreases the degranulation capacity of NK cells but, strikingly, this effect cannot be rescued by a subsequent stimulation with rituximab. The strength of perforin secretion is also translated to killing of Daudi target cells, expressing different ligands. When Daudi, opsonised with rituximab is the first target NK cell encounters, the sequential killing of another opsonised rituximab or Daudi, expressing MICA will not be affected. But, when Daudi-MICA is met first, the consecutive killing of Daudi-MICA as well as Daudi-rituximab will be impaired. We found that the mechanism underlying these differential outcomes involves shedding of CD16, which occurs upon NK cell activation through both, CD16 and NKG2D. Shedding of CD16 renders the cells insensitive to further activation via that receptor but they remain competent for further activation through NKG2D. Interestingly, however, we also identified the beneficial role of CD16 shedding for NK cell serial killing. NK cells are more motile on rituximab-coated surfaces than on MICA-coated surfaces and their migration speed decreases upon inhibition of CD16 shedding. Moreover, the inhibition of CD16 shedding also prevents the NK cell detachment from rituximab opsonised Daudi cells. Thus, the shedding of the receptor can serve to augment NK cell motility to move between target cells. Efficient NK cell detachment also correlated with their increased survival. Finally, we report that CD16 is constitutively organised in small, dense nanoclusters and that the ligation with rituximab does not affect their spatial distribution. Despite the shedding of the receptor, leading to less protein molecules at the surface, the area of these clusters remains the same. Together these data suggest that CD16 shedding hinders NK cell cytotoxicity against opsonised targets, but promotes their movements between different targets. Thus, receptor shedding is important for efficient NK cell serial killing. Manipulation of CD16 shedding, perhaps by boosting its recovery, might therefore represent an important target for NK cell-based therapies including treatments with therapeutic antibodies.

O Brasil é o maior produtor mundial de cana-de-açúcar, com uma área cultivada de aproximadamente 10 milhões de hectares. Em se tratando da sustentabilidade ambiental dessas áreas nota-se que há ainda um grande caminho a ser percorrido. Um dos problemas mais agudos é a erosão do solo e as suas implicações que trazem prejuízos ao produtor, à comunidade, à economia e ao meio ambiente. Neste estudo, objetivou-se investigar a erosão hídrica em uma microbacia de 6 hectares, nas duas vertentes cobertas por cana-de-açúcar, e com a presença de floresta na área ripária, em conformidade com o Código Florestal Brasileiro. Para isso, pluviômetros foram instalados para medir o volume e a intensidade das chuvas. A geração de escoamento superficial e da perda de solo foram estimados por parcelas instaladas nas duas vertentes cultivadas com cana-de-açúcar e na floresta ripária. Batimetria foi realizada no canal para avaliar o volume de sedimento depositado no riacho. A origem deste material foi determinada pelas composições isotópicas do carbono, expresso com ? 13C, utilizando-se como referência amostras de solo de áreas manejadas com cana-de-açúcar e floresta ripária. Nos estágios iniciais da cultura, a intensidade da chuva influenciou significativamente a ocorrência de escoamento e a desagregação do solo; que foram minimizadas com o crescimento da cana. Na floresta ripária, o escoamento superficial e a desagregação do solo ocorreram somente durante eventos intensos. Em uma das vertentes, cerca de 5% da precipitação anual foi drenada como escoamento superficial; na outra vertente, esta proporção aumentou para aproximadamente 11% e na floresta ripária diminuiu para menos de 2%. A perda do solo foi de aproximadamente 1.000 g m-2 em uma vertente, aumentou para cerca de 5.000 g m-2 na outra vertente, decrescendo para apenas 50 g m-2 na floresta ripária. Através da batimetria, estimou-se que 3,6 Mg de sedimentos por hectare foram carreados no riacho durante a estação chuvosa. A análise das composições isotópicas indicou que cerca de 30% da matéria orgânica presente no sedimento do riacho foi proveniente das áreas de cana e os outros 70% foram provenientes das áreas de floresta / Brazil is the world largest sugarcane producer, with a cropped area of approximately 10 million hectares. Soil erosion and its implications are some of the neglected environmental problems in sugarcane fields. In this study a plot of 6 hectares cropped with sugarcane, encompassing a 30 meters of riparian forest bordering a stream was chosen. Two pluviometers were installed in an open area in order to measure the amount and intensity of rain during the rainy season. Surface runoff generation and soil detachment were estimated by plots installed in cultivated and riparian areas. Bathymetry was carried out in the stream channel to estimate the soil mass settled on the stream bed. The sources of organic matter were investigated by carbon (?13C) stable isotopic compositions. In the earlier stages of the crop, the rain intensity strongly influenced runoff generation and soil detachment; that were minimized with the plant growth. In riparian areas, runoff and soil detachment occurred only during intense events. The total rainfall was approximately 1,500 mm, in one slope of the sugarcane field, approximately 5% of this rainfall drained from the watershed as surface runoff; in the other slope this proportion increased to approximately 11%, and in the riparian forest decreased to less than 2%. The soil detachment was approximately 1,000 g m-2 in one sugarcane slope, and increased to approximately 5,000 g m-2 in the other slope, decreasing in the riparian forest to only 50 g m-2. Using the bathymetry conducted in the stream channel, we estimated that 3.6 Mg of sediment per hectare were settled on the stream bed during the rainy season. The averages ?13C of soil from forest and sugarcane areas and in the stream bed indicated that 30% of this material was generated in the sugarcane areas and 70% in the riparian forest

O Brasil é o maior produtor mundial de cana-de-açúcar, com uma área cultivada de aproximadamente 10 milhões de hectares. Em se tratando da sustentabilidade ambiental dessas áreas nota-se que há ainda um grande caminho a ser percorrido. Um dos problemas mais agudos é a erosão do solo e as suas implicações que trazem prejuízos ao produtor, à comunidade, à economia e ao meio ambiente. Neste estudo, objetivou-se investigar a erosão hídrica em uma microbacia de 6 hectares, nas duas vertentes cobertas por cana-de-açúcar, e com a presença de floresta na área ripária, em conformidade com o Código Florestal Brasileiro. Para isso, pluviômetros foram instalados para medir o volume e a intensidade das chuvas. A geração de escoamento superficial e da perda de solo foram estimados por parcelas instaladas nas duas vertentes cultivadas com cana-de-açúcar e na floresta ripária. Batimetria foi realizada no canal para avaliar o volume de sedimento depositado no riacho. A origem deste material foi determinada pelas composições isotópicas do carbono, expresso com ? 13C, utilizando-se como referência amostras de solo de áreas manejadas com cana-de-açúcar e floresta ripária. Nos estágios iniciais da cultura, a intensidade da chuva influenciou significativamente a ocorrência de escoamento e a desagregação do solo; que foram minimizadas com o crescimento da cana. Na floresta ripária, o escoamento superficial e a desagregação do solo ocorreram somente durante eventos intensos. Em uma das vertentes, cerca de 5% da precipitação anual foi drenada como escoamento superficial; na outra vertente, esta proporção aumentou para aproximadamente 11% e na floresta ripária diminuiu para menos de 2%. A perda do solo foi de aproximadamente 1.000 g m-2 em uma vertente, aumentou para cerca de 5.000 g m-2 na outra vertente, decrescendo para apenas 50 g m-2 na floresta ripária. Através da batimetria, estimou-se que 3,6 Mg de sedimentos por hectare foram carreados no riacho durante a estação chuvosa. A análise das composições isotópicas indicou que cerca de 30% da matéria orgânica presente no sedimento do riacho foi proveniente das áreas de cana e os outros 70% foram provenientes das áreas de floresta / Brazil is the world largest sugarcane producer, with a cropped area of approximately 10 million hectares. Soil erosion and its implications are some of the neglected environmental problems in sugarcane fields. In this study a plot of 6 hectares cropped with sugarcane, encompassing a 30 meters of riparian forest bordering a stream was chosen. Two pluviometers were installed in an open area in order to measure the amount and intensity of rain during the rainy season. Surface runoff generation and soil detachment were estimated by plots installed in cultivated and riparian areas. Bathymetry was carried out in the stream channel to estimate the soil mass settled on the stream bed. The sources of organic matter were investigated by carbon (?13C) stable isotopic compositions. In the earlier stages of the crop, the rain intensity strongly influenced runoff generation and soil detachment; that were minimized with the plant growth. In riparian areas, runoff and soil detachment occurred only during intense events. The total rainfall was approximately 1,500 mm, in one slope of the sugarcane field, approximately 5% of this rainfall drained from the watershed as surface runoff; in the other slope this proportion increased to approximately 11%, and in the riparian forest decreased to less than 2%. The soil detachment was approximately 1,000 g m-2 in one sugarcane slope, and increased to approximately 5,000 g m-2 in the other slope, decreasing in the riparian forest to only 50 g m-2. Using the bathymetry conducted in the stream channel, we estimated that 3.6 Mg of sediment per hectare were settled on the stream bed during the rainy season. The averages ?13C of soil from forest and sugarcane areas and in the stream bed indicated that 30% of this material was generated in the sugarcane areas and 70% in the riparian forest

Abstract Multiphase Droplet Interactions with a Single Fiber By: Noor M. Farhan A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Virginia Commonwealth University. Virginia Commonwealth University, 2019 Director: Hooman V. Tafreshi, Professor, Department of Mechanical and Nuclear Engineering Formulating the physics of droplet adhesion to a fiber is interesting intellectually and important industrially. A typical example of a droplet–fiber system in nature is the dew droplets on spider webs, where droplets first precipitate and grow on the fibers, but they eventually fall when they become too heavy. Obviously, quantifying the force of adhesion between a droplet and a fiber is crucial in designing fog harvesting devices or manufacturing filtration media for liquid–gas or liquid–liquid separation, among many other industrial applications. This study is aimed at developing a mathematical framework for the mechanical forces between a droplet and a fiber in terms of their physical and wetting properties. To this end, a series of experiments were conducted to detach ferrofluid droplets of varying volumes from fibers with different diameters and Young–Laplace contact angles (YLCAs) in a controlled magnetic field. The force of detachment was measured using a sensitive scale and used along with the results of numerical simulations to develop a semi-analytical expression for the force required to detach a droplet from a fiber. This universally-applicable expression allows one to predict the force detachment without the need to run an experiment or a computer simulation. This work also reports on the use of magnetic force to measure the force of detachment for nonmagnetic droplets for the first time. This is accomplished by adding a small amount of a ferrofluid to the original nonmagnetic droplet to create a compound droplet with the ferrofluid nesting inside or cloaking the nonmagnetic droplet. The ferrofluid is then used to induce a body force to the resulting compound droplet and thereby detach it from the fiber. The recorded detachment force is used directly (the case of nesting ferrofluid) or after scaling (the case of cloaking ferrofluid) to obtain the force of detachment for the original nonmagnetic droplet. The accuracy of these measurements was examined through comparison with numerical simulations as well as available experimental data in the literature. In addition, a simple method is developed to directly measure the intrinsic contact angle of a fiber (i.e., Young–Laplace Contact angle of the fiber material) with any arbitrary liquid. It is shown that the intrinsic contact angle of a fiber can be obtained by simply measuring the angle between the tangent to the fiber surface and the tangent to the droplet at the contact line, if the droplet possesses a clamshell conformation and is viewed from the longitudinal direction. The novelty of the proposed method is that its predictions are not affected by the volume of the droplet used for the experiment, the wettability of the fiber, the surface tension of the liquid, or the magnitude of the body force acting on the droplet during the experiment. Also, a liquid droplet interaction with granular coatings is simulated and the droplet apparent contact angle (ACA) and the transition from Cassie (fully dry) to Wenzel (fully wet) state as a function to the roughness wavelength have been studied. For a fixed droplet volume, two different granular coatings have been used, spherical and hemispherical bumps. It is demonstrated that the chemistry (YLCA) and geometrical parameters for the granular microtexture play an important effect on the droplet ACA and its transition from Cassie to Wenzel state.

<p><span lang="EN-GB" style="font-size:12.0pt / font-family:&quot / Times New Roman&quot / ,&quot / serif&quot / mso-fareast-font-family:&quot / Times New Roman&quot / mso-ansi-language:EN-GB / mso-fareast-language: EN-ZA">Literature shows that cataracts are the leading cause of blindness globally and nationally. Retinal detachment has also been a substantial problem both globally and nationally. Both of these conditions are prevalent in patients of 50 years and older. The treatment for both conditions is for surgery to be performed. In the Western Cape the three leading hospitals do not have ophthalmic pre-operative and post-operative protocols<span style="mso-bidi-font-weight:bold">.</span>Review question:What are the best practices to manage pre-operative and post-operative nursing care in patients waiting for cataract and retinal detachment surgery? bjectives:1. To determine the best practice in pre-operative and post-operative care in patients who have undergone cataract and/or retinal detachment surgery regarding: health education offered by nurses, counselling to prevent psychological effects, and positioning to prevent physical complications. 2. To develop a framework based on systematic reviews for pre-operative and post-operative ophthalmic nursing care in South Africa. Methodology: </span><span lang="EN-GB" style="font-size: 12.0pt / font-family:&quot / Times New Roman&quot / ,&quot / serif&quot / mso-ansi-language:EN-GB">A systematic review using the guide by the Centre for Reviews and Dissemination was done, and <span style="mso-bidi-font-weight:bold">studies were </span>identified by searching various electronic databases and visually scanning reference lists from the relevant studies. Studies that were included were evidence-based. All study types were considered and the studies were selected based on the title and, where available, the abstract. These were then assessed against the inclusion criteria. A narrative synthesis was used. Finally the evidence was summarised and a framework was drawn up, focusing on pre-operative and post-operative nursing care for cataract and retinal detachment surgery</span></p> <p>&nbsp / </p>

Children of alcoholics (COAs) are those who grow up in a home where one or more parent is an alcoholic; once adulthood is achieved, they are referred to as adult children of alcoholics (ACOAs). Several risk factors have been identified as a potential result from exposure to an alcoholic environment; however there is a dearth of literature exploring resilience in this population. Descriptive Narrative Inquiry was used to explore the question, Describe the qualities, processes, or internal motivational factors which have facilitated resilience for adult children of alcoholic parents. Two ninety-minute life history interviews were conducted with four participants, including the researcher. The participants were female, middle class, university students who considered themselves to be adult children of alcoholics who are resilient. A composite narrative was used to depict the results of this study, combining the data from each participants life story. The narrative was written in the first-person through the character of Sophie, and the data included is the result of a narrative analysis from the transcripts of the participants data. The narrative depicts the developmental stages of the participants lives, including childhood, adolescence, adulthood, and the present. Their experiences of growing up in an alcoholic home were documented at each stage. A thematic analysis was conducted, extracting the common themes, meaning made, and personal characteristics that were generated within and across participants that contributed to their development of resilience. The results are discussed in four major themes: Being in Relation: Others Create a Difference; Belief Systems: Spirituality, Religion, and Values; The Self: An Evolving Being; and Alcoholism: Meaning in Itself. It is through the dialogue of the participants experiences of resilience that awareness creates opportunity for advocacy for children and adult children of alcoholics. The implications of this research in relation to the experiences of resilience are discussed for children and adult children of alcoholics, educators, and counsellors. Directions for future research are addressed.

Plasma flow physics in magnetic nozzles must be clearly understood for optimal design of plasma propulsion devices. Toward that end, in this thesis we: i) perform an extensive literature survey of magnetic nozzle physics, ii) assess the validity of magnetohydrodynamics for studying magnetic nozzle physics, and iii) illustrate the effects of the Hall term in simple flows as well as in magnetic nozzle configurations through numerical experiments with the Magneto-Gas Kinetic Method (MGKM). The crucial steps necessary for thrust generation in magnetic nozzles are energy conversion, plasma detachment, and momentum transfer. These three physical phenomena must be understood to optimize magnetic nozzle design. The operating dimensionless parameter ranges of six prominent experiments are considered and the corresponding mechanisms are discussed. An order of magnitude analysis of the governing equations reveal: i) most magnetic nozzles under consideration operate at the edge of the continuum regime rendering continuum-based description and computation valid; ii) in the context of MHD framework, the generalized Ohm’s law must be used to capture all of the relevant physics. This work also continues the development of the Magneto Gas Kinetic Method (MGKM) computational tool. Validation of the solver is performed in shock-tube and Hartmann channel flows in the Hall physics regime. Comparison with theory and available data is made whenever possible. Novel numerical experiments of magnetic nozzle plasma jets in the Hall regime are performed, confirming the theoretically predicted azimuthal rotation of the plasma jet due to Hall physics. The primary conclusion from this work is that the addition of the Hall effect generates helical structures in magnetic nozzle plasma flows. Preliminary results are encouraging for future magnetic nozzle studies and further challenges are identified.

No description available.

Children of alcoholics (COAs) are those who grow up in a home where one or more parent is an alcoholic; once adulthood is achieved, they are referred to as adult children of alcoholics (ACOAs). Several risk factors have been identified as a potential result from exposure to an alcoholic environment; however there is a dearth of literature exploring resilience in this population. Descriptive Narrative Inquiry was used to explore the question, Describe the qualities, processes, or internal motivational factors which have facilitated resilience for adult children of alcoholic parents. Two ninety-minute life history interviews were conducted with four participants, including the researcher. The participants were female, middle class, university students who considered themselves to be adult children of alcoholics who are resilient. A composite narrative was used to depict the results of this study, combining the data from each participants life story. The narrative was written in the first-person through the character of Sophie, and the data included is the result of a narrative analysis from the transcripts of the participants data. The narrative depicts the developmental stages of the participants lives, including childhood, adolescence, adulthood, and the present. Their experiences of growing up in an alcoholic home were documented at each stage. A thematic analysis was conducted, extracting the common themes, meaning made, and personal characteristics that were generated within and across participants that contributed to their development of resilience. The results are discussed in four major themes: Being in Relation: Others Create a Difference; Belief Systems: Spirituality, Religion, and Values; The Self: An Evolving Being; and Alcoholism: Meaning in Itself. It is through the dialogue of the participants experiences of resilience that awareness creates opportunity for advocacy for children and adult children of alcoholics. The implications of this research in relation to the experiences of resilience are discussed for children and adult children of alcoholics, educators, and counsellors. Directions for future research are addressed.

published_or_final_version / Anatomy / Master / Master of Philosophy