Identification and evaluation of techniques for quality control of low-cost xylem filters

Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018.Cataloged from PDF version of thesis.Includes bibliographical references (pages 49-51).2.1 billion people worldwide, majority of whom are of the poorest income quintile, lack access to safe, readily available water in their homes. The need for affordable, decentralized methods of water filtration led to the development of a low-cost membrane filter produced from the xylem of coniferous trees. Due to xylem structure variation and the potential for improper filter processing during mass production, quality control protocols are a necessity. Manufacturers must ensure xylem filters are functional in terms of microbial rejection and adequate flow rates. Testing methods similar to those mentioned in this thesis can also be developed for other membrane filters. The suitability of two fluids, water and air, were evaluated for use in the quality control process. For testing using water, turmeric and blue dye were used to create a visual indication test to detect a filter's major failures. We found that this method has the potential to detect both leaks and improperly prepared filters, but it lacks affordable, quantitative analysis for determining rejection percentages. Air was found to be a viable option for xylem filter testing at pressures of 6 psi and above, though presence of the xylem lowered the concentration of particles detected at the outlet by one-fourth. The substances found to be most suitable for testing the filter were Baker's yeast, jeweler's rouge, turmeric, and buttermilk given their affordability, particle/microbe size, and availability. Further exploration is required to determine the optimal particle to use in water and air testing and the equipment necessary for the quality control process to be implemented.by Bettina K. Arkhurst.S.B

Impact of endoluminal stenting for aortic surgery

The advent of stents has profoundly changed percutaneous transluminal coronary angioplasty (PTCA), peripheral transluminal artery angioplasty (PTA), and treatment strategies of numerous other problems. Similar developments can be observed for stent applications in peripheral vascular lesions, cerebro-vascular disease, and many other fields. With the advent of covered stent-grafts, aneurysm surgery, has been put up for competitive treatment approaches. Such new approaches are perceived as less invasive, and draw significant attention. Endovsacular aneurysm repair (EVAR) is here to stay. In addition new developments are coming in many ways and stent derived devices can by now be found everywhere in the cardio-vascular system. This includes stenosed vessels, aneurysmal vessels, diseased valves, all sorts of congenital heart defects, and even cardiopulmonary bypass. The key technologies and know-how for EVAR are available or can be made available in most cardio-vascular surgical units. Special interest in this field (clinical and/or experimental) can enhance recruitment of patients. The opposite is also tru

Brain region–specific lipid alterations in the PLB4 hBACE1 knock-in mouse model of Alzheimer’s disease

We are grateful to the Alzheimer’s Society Scottish Doctoral Training Centre and the RS Macdonald Trust Transition Fund for funding the research presented.Peer reviewedPublisher PD

Comparison of automated video tracking systems in the open field test : ANY-Maze versus EthoVision XT

This project included funding from the Innovative Medicines Initiative 2/EFPIA, European Quality in Preclinical Data (EQIPD) consortium under grant agreement number 777364. We would also like to acknowledge the staff of the Medical Research Facility for their support with animal care, handling and behavioural experiments.Peer reviewedPostprin

Validation of a German Version of the Grief Cognitions Questionnaire and Establishment of a Short Form

Background: Whereas the majority of bereaved persons recover from their grief without professional assistance, a minority develops pathological grief reactions. Etiological models postulate that dysfunctional cognitions may perpetuate such reactions. The Grief Cognitions Questionnaire (GCQ) assesses thoughts after bereavement in nine interrelated domains. A short form (GCQ-SF) with four domains is often used. However, an evaluation of the psychometric properties of the GCQ-SF and its utility compared to the GCQ is lacking and these instruments have not been validated in German. Method: German bereaved persons (time since loss 35.3 ± 34.6 months) responded to an online survey containing the GCQ, measures of grief severity, grief rumination, symptoms of depression and anxiety, and optimism and pessimism. 585 participants (18–78 years, 88% women) were included. Item analyses and confirmatory factor analyses were conducted. Correlations between the GCQ and GCQ-SF and grief rumination, optimism and pessimism assessed construct validity. Criterion-related validity was assessed by comparing whether the correlation of the GCQ (and the GCQ-SF) with grief severity was higher than with anxious and depressive symptoms. Logistic regression and receiver-operator characteristics (ROC) compared the questionnaires on their ability to predict probable prolonged grief ‘caseness’ (ICG ≥ 25, time since loss ≥6 months). Results: Internal consistencies for both questionnaires were identical and excellent (α = 0.96). Confirmatory factor analyses obtained a satisfactory fit for models with nine and four correlated subscales and respective higher-order factor models. The GCQ and the GCQ-SF correlated higher with grief severity than with other measures of psychopathology. The logistic regression showed a significant association between the GCQ-SF and prolonged grief ‘caseness’. Of the remaining subscales of the GCQ, only one subscale (‘Others’) contributed to the prediction. The ROC analyses showed nearly identical areas under the curve. Conclusion: The translated GCQ and GCQ-SF demonstrated very good psychometric properties. The correlations with grief severity highlight the questionnaires’ clinical relevance. The questionnaires possessed identical diagnostic specificity and sensitivity. Whenever a timesaving assessment of the most typical grief-specific cognitions is important, the GCQ-SF represents an alternative to the GCQ. The original GCQ may still be superior when a more detailed description of a bereaved person’s cognitions is desirable

Doubly Illegal: Qualitative Accounts of Underage Alcohol Access Through Theft

This study investigated sources of alcohol for underage drinkers. In-depth, semi-structured interviews were individually conducted with 47 youths, ages 15-18, who reported drinking within the last 12 months, to explore alcohol access. Theft was one method that some youths reported using to obtain alcohol. In addition to 9% of respondents who reported stealing alcohol from commercial outlets themselves, a total of 26% respondents reported occasions when their close friends stole alcohol. Our findings unveiled that teens had a body of knowledge that some drew upon for stealing alcohol. Youths revealed detailed knowledge about store layout, theft protection devices and store policies. In particular, respondents disclosed knowledge about which aisles have blind spots, how to remove security tops on bottles, and nochase policies. Theft of alcohol from commercial sources may be reduced by examining the weaknesses of existing theft prevention practices, and revising store policies