1,659 research outputs found
EVALUATING VEGETABLE PRODUCTION FOR MARKET WINDOWS AS AN ALTERNATIVE FOR LIMITED RESOURCE FARMERS
Crop Production/Industries,
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New methodology to measure the dynamics of ocular wave front aberrations during small amplitude changes of accommodation
We present a methodology to measure the systematic changes of aberrations induced by small changes in amplitude of accommodation. We use a method similar the one used in electrophysiology, where a periodic stimulus is presented to the eye and many periods (epochs) of the stimulus are averaged. Using this technique we have measured changes in higher order aberrations from 0.006ÎĽm to 0.02ÎĽm and correlated them with amplitude changes of accommodation as small as 0.14D. These small changes would have been undetectable without epoch averaging. The correlation coefficients of Zernike terms with defocus were calculated, demonstrating higher values of correlation for epoch averaging. The accurate monitoring of defocus at the start of the accommodation response has shown some interesting trends that may be related with the mechanisms behind accommodation
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Amyloidogenesis of β-2-microglobulin Studied by Mass Spectrometry and Covalent Labeling
Amyloid-forming proteins are implicated in a number of debilitating diseases. While many amyloid-forming proteins are well studied, the early stages of amyloidosis are still not well understood on a molecular level. Covalent labeling, combined with mass spectrometry (CL-MS), is uniquely well suited to provide molecular-level insight into the factors governing the early stages of amyloidosis. This dissertation leverages CL-MS techniques to examine the early stages of β-2-microglobulin (β2m) amyloidosis. β2m is the protein that forms amyloids in the condition known as dialysis-related amyloidosis. An automated CL-MS technique that uses dimethyl(2-hydroxy-5-nitrobenzyl) sulfonium bromide as a labeling reagent was developed and used to measure energy barriers to the initial pre-amyloid structural change of β2m under different amyloid-forming conditions. The results represent the first ever measure of the activation barrier for a structural change initiating amyloid formation. The results also give new mechanistic insight into β2m’s amyloidogenic structural change, particularly the role of Pro32 isomerization. The catalytic nature of Cu(II) as an initiator of the β2m pre-amyloid structural change was confirmed as it significantly lowered the energy barrier to this structural change. It also appears that, when initiated by acid, the Pro32 isomerization may no longer be the rate limiting step in this process.
The same technique was further used to investigate the β2m structural change caused by its interaction with an amyloidogenic variant of β2m called ΔN6-β2m, which is missing its first six N-terminal residues. Both primary and secondary nucleation events involved in the β2m/ΔN6-β2m interaction were investigated. The measured barrier for the primary nucleation event seems to indicate that, like the acid induced structural change of β2m, the isomerization of Pro32 may not be the rate determining step. However, the measured barrier for the secondary nucleation event, similar to that of the Cu(II) induced structural change, indicates that the isomerization of Pro32 is the rate determining step. The use of point mutants gives further detail on the crucial residues and regions of the proteins required for a productive interaction to yield amyloids. The new kinetic and thermodynamic information gained in this work yields new insight into the mechanistic details of the biomedically important process of β2m amyloidosis
The multifocal pattern electroretinogram in chloroquine retinopathy
Purpose: Optimal screening for ocular toxicity caused by chloroquine and hydroxychloroquine is still controversial. With the multifocal pattern electroretinogram (mfPERG), a new electrophysiological technique has recently become available to detect early changes of ganglion cells. In this study this new technique is applied to a series of 10 patients seen consecutively receiving long-term chloroquine medication. Methods: In 10 patients receiving chloroquine medication, clinical examination, Amsler visual field testing and computerized color vision testing were performed. If toxicity was suspected, automated perimetry was carried out. In addition, in all patients conventional pattern electroretinogram (PERG) and mfPERG testing were performed. Results: On clinical examination 8 patients showed no chloroquine-associated maculopathy, while 2 patients did. Of these 2, only 1 reported abnormalities when viewing the Amsler chart, while automated perimetry showed typical, ring-like paracentral scotomas in both affected patients and color vision was significantly abnormal. In the normal patients, 4 of 8 had a mild color vision disturbance, which correlated to age-related macular changes. The amplitudes of the PERG and the central (approximately 10degrees) responses of the mfPERG were markedly reduced in chloroquine maculopathy, while the latencies were unchanged. The peripheral rings of mfPERG (ranging to 48degrees) were not affected by chloroquine toxicity. Both PERG and mfPERG were less affected by age-related macular changes. Conclusions: The reduction of PERG and central mfPERG responses in chloroquine maculopathy may help with the early detection of toxicity. Copyright (C) 2004 S. Karger AG, Basel
Developing digital interventions: a methodological guide.
Digital interventions are becoming an increasingly popular method of delivering healthcare as they enable and promote patient self-management. This paper provides a methodological guide to the processes involved in developing effective digital interventions, detailing how to plan and develop such interventions to avoid common pitfalls. It demonstrates the need for mixed qualitative and quantitative methods in order to develop digital interventions which are effective, feasible, and acceptable to users and stakeholders
Evaluating Dryland Crop/Livestock System Alternatives for Risk Management under Declining Irrigation in the Texas Panhandle
Production budgets for dryland crop and crop/livestock systems are developed to estimate yields, costs and returns for dryland wheat and sorghum and for alternative dryland crop/livestock systems. A crop simulation model aids yield estimation. The yield and return distributions are used to estimate risk and relative risk for included alternatives.Relative Risk, Ogallala Aquifer, Crop-Livestock Systems, Wheat, Sorghum, Crop Production/Industries, Farm Management, Livestock Production/Industries, Production Economics, Productivity Analysis,
Gender Differences: Smokers With and Without Substance Abuse History
poster abstractPrevious research suggests that individuals with chemical dependence history experience more
intense nicotine addiction, and during smoking cessation may be more likely to demonstrate
increased negative affect and unfavorable scores on psychometric assessments. It is unknown
how men and women may differ in their susceptibilities to such undesirable outcomes. From
1992-2004, The Indiana University Nicotine Dependence Program (IUNDP) treated over 1200
patients using a Mayo Clinic-based protocol which assesses the behavioral, social, and
physiological aspects of nicotine dependence. The IUNDP was instituted at Fairbanks Hospital’s
addictions center to address tobacco use among the patients and staff. Charts of individuals
who completed nicotine dependence treatment (1992-2011) were selected from IU School of
Dentistry and Fairbanks Hospital for retrospective analysis. Chart selection criteria consisted of
the availability of complete pre-and post quit measures for a minimum of four total appointments
and two post-quit appointments. Reviewed were 107 charts from patients without a history of
chemical dependence (ND) and 123 from those with a chemical dependence history (CD),
including 120 men and 110 women. Student researchers used a standardized protocol to
capture 16 tobacco use and demographic variables and 12 post-quit measures. Comparisons
between CD and ND groups were made using Pearson chi-square tests for binary data,
Wilcoxon rank sum tests for all other data, and Wilcoxon signed rank tests for changes between
time periods. Despite similarities among CD and ND smokers, males and females appear to
face distinct challenges. Results suggest CD males are significantly more negative in mood, and
are more likely to have increased withdrawal symptoms at the end of treatment. Males were
also more likely to experience adverse events with NRT. Both CD males and females
experienced more increased appetite than their ND counterparts. Females scored higher on
addiction-related sensorimotor manipulation and may have increased propensity for
psychological dependence
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