När informationsmängden överskrider den mänskliga kognitiva förmågan att hantera information leder detta till information overload. Tidigare studier har visat att information overload har en negativ påverkan på förmågan att hitta det bästa alternativet. Även viljan att köpa en produkt har visats bli negativt påverkad av för många alternativ. Denna fältstudie utfördes i en online-miljö på en jämförelsesida för snabblån och undersökte om andelen besökare som klickade sig vidare till ett alternativ, det som i studien benämns som konverteringsgrad, kunde påverkas genom att antalet synliga alternativ manipulerades. Tre versioner av samma sida jämfördes med varandra. En version hade den fulla listan med 26 alternativ, en annan version visade endast fem alternativ och en tredje visade fem alternativ med en möjlighet för besökaren att genom en knapptryckning visa alla. I motsats till tidigare forskning uppvisade experimentet en ökad konverteringsgrad med fler alternativ. När besökare använde kringliggande funktionalitet, såsom filtrerings- funktioner eller knappen för att visa alla alternativ ökade konverteringsgraden. Det spelade ingen roll om besökare ökade informationsmängden genom att expandera listan eller om de minskade informationsmängden genom filtrering, båda dessa grupper visade en högre konverteringsgrad.

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The problem of this study was to investigate through experimentation whether or not there would be any significant improvement of one hundred and fifty girls enrolled in the seventh and eighth grades of Azle Junior High School of Azle, TX, in their performance of the volleyball volley and serve upon the completion of prescribed programs.

Choice overload is characterized by individuals experiencing a decrease in preference strength and satisfaction (Chemey, 2003) in conjunction with increases in disappointment and regret regarding a chosen option (Schwartz, 2000). Choice overload has been examined in a variety of situations, however choice overload has not been examined with individuals with developmental disabilities or during stimulus preference assessments. While extensive research has been conducted regarding stimulus preference assessments, no research has been conducted evaluating the most effective number of items to use during preference assessments. The purpose of the present study was to compare using six and 18 item arrays during a multiple stimulus without replacement preference assessment, to evaluate the accuracy of both procedures with a reinforcer assessment, and to evaluate the behavior of participants for characteristics of choice overload during the preference and reinforcer assessments. The results of the present study suggest that the results between the six and 18 item preference assessments are strongly consistent; however the six item assessments overestimated the reinforcer efficacy of numerous items in comparison to the 18 item preference assessment. The results also suggest that two participants displayed characteristics associated with choice overload and that a certain level of cognitive functioning may be required for choice overload to occur.

Background: Many COPD patients have recurrent exacerbations due to infection, but there are no valid predictors of this phenotype. Previously an observational study showed that higher iron content in sputum macrophages was associated with infectious exacerbations. Objectives: The thesis aimed to assess the mechanisms of pulmonary macrophage iron sequestration, test the effect of macrophage iron-loading on bacterial uptake and killing, and prospectively determine if sputum hemosiderin index can predict infectious exacerbations of COPD. Methods: Intracellular iron was measured directly and indirectly in cell-line-derived and isolated sputum macrophages after treatment with exogenous IL-6, hepcidin or heat-inactivated H.influenzae. Bacterial uptake and killing were compared in both types of macrophages, in the presence or absence of iron-loading. A prospective cohort of COPD patients had their sputum hemosiderin index measured at baseline and were monitored for 1-year for infectious exacerbations requiring admission to hospital. Results: For pulmonary iron sequestration, IL-6 appears important, but the role of hepcidin is not clear. Iron-loading reduced the uptake of COPD-relevant organisms by almost one-third in cell-line-derived macrophage, and there was a near-significant linear relationship between sputum hemosiderin index and killing of H.influenzae (p=0.075). In terms of infective exacerbations, FEV1 had predictive utility (beta=-0.051, p=0.017) while a positive trend for sputum hemosiderin index (beta=0.035, p=0.051) suggests that this biomarker has clinical promise. Conclusion: Through in vitro experiments and cohort data, we have established a framework suggesting that excess iron in pulmonary macrophage may contribute to recurrent bacterial airway infection in COPD. IL-6 appears to contribute to sputum macrophage iron sequestration, which subsequently may lead to immune cell dysfunction and ultimately result in an increased frequency of infective exacerbation. / Thesis / Master of Science (MSc) / COPD patients often require hospitalization due to respiratory infections (bacterial or viral) that result in worsening of their breathing. It is difficult to predict who is at high risk for this to occur, which makes it harder to prevent. Many species of bacteria depend on iron as a nutrient. We wanted to see if iron being present in certain immune cells (macrophages) in the sputum could predict these flares by: testing how iron enters these cells, seeing if bacterial growth is altered by putting iron into these cells, and following a group of COPD patients and seeing if those with higher iron in their sputum had higher risk of infectious flares. Though more testing is needed, we found that a protein often present with chronic inflammation may be associated with higher sputum macrophage iron, and that there is evidence that killing of bacteria in COPD sputum macrophages is lower with high iron, and that patients with higher sputum iron are at greater risk of having infectious flares.

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Thesis (M.D.)--Boston University