Measuring cycling kinematics using a low-cost, flashing LED, multi-camera approach

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.Includes bibliographical references (p. 60).In this thesis a low cost motion capture approach is presented and applied to measure cyclists' kinematics. The motion capture system consists of low cost hardware and custom developed software. Based on still-frame, off-the-shelf digital cameras, the method represents a solution which is accessible to the average athlete. With the exception of off-the-shelf digital cameras the total cost of the hardware is less than $100. The motion capture system is applied to study cyclist kinematics for three different types of bicycles: road bikes, triathlon bikes, and mountain bikes. Coupled with power output measurement and wind tunnel drag measurements, the investigation of several different standard cycling positions is performed. The results indicate a significant component of out-of- plane joint motions, especially in the knee, with an average knee excursion between 0.15" and 0.21". The system was also used to measure cycling cadence, with a range between 1.06Hz and 1.63Hz. Joint angle analysis suggested a positive correlation between ankle angle range and power output. Further in-depth analyses of these data or similar data collected using these motion capture approaches may give deeper insight into which motions correlate with higher power outputs. Wind tunnel and power data were used to calculate position transition velocities for different exertion levels and hill angles. This low-cost system was demonstrated to be a useful and effective tool for measuring and analyzing cycling kinematics.by Matthew Gilbertson.S.B

Hand held force-controlled ultrasound probe

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 129-131).An hand-held force controlled ultrasound probe has been developed. The controller maintains a prescribed contact force between the probe and a patient's body. The device will enhance the diagnostic capability of free-hand elastography, swept-force compound imaging, and make it easier for a technician to acquire repeatable (i.e. directly comparable) images over time. The mechanical system consists of an ultrasound probe, ballscrew-driven linear actuator, and a force/torque sensor. The feedback controller commands the motor to rotate the ballscrew to translate the ultrasound probe in order to maintain a desired contact force. In preliminary user studies it was found that the control system maintained a constant contact force with 1.7 times less variation than human subjects who watched a force gauge. Users without a visual force display maintained a constant force with 20 times worse variation. The system was also used to determine the viscoelastic properties of soft tissue. In three mock ultrasound examinations one hour apart in which the goal was two obtain two consistent images at the same force, an unassisted operator obtained the second image at a 20% lower force, while the operator assisted by the controller obtained the same force to within <2%. The device enables users to gather more force-consistent images over time.by Matthew Wright Gilbertson.S.M

Tapered Fluidized Beds and the Role of Fluidization in Mineral Emplacement

One of the most prominent features of fluidized beds is their ability to mix and segregate. This is of great importance for many industrial processes, but takes on a particular significance for mineral extraction where a small amount of valuable matter is mixed with a large amount of waste. In this study we consider the occurrence of diamonds in the volcanic rock called “kimberlite”. These are often emplaced (erupted and deposited) in large volcanic pipes commonly referred to as “diatremes” (length scale of the order of a kilometre) with a vent at the bottom through which the minerals were introduced along with other fragmental particulate matter and a gas flow. The purpose of this study is to gain an understanding of the processes that led to the dispersal of minerals before their emplacement to allow efficient extraction. The paper describes experimental observations of a tapered fluidized bed. The objective was to identify the physical behaviour of gas and particles; so, of particular interest are the extent to which fluidization takes place within the bed, and the arrangements of particles seen. Gas flow-rate, particle size, and degree of taper were all varied. These observations can be used to identify the structures and processes that can take place; it is then possible to understand field data in terms of the physics that led to the emplacement of material. This will be shown using new data taken from southern Africa. Scale-up of evidence is of obvious difficulty in this system and this is discussed in terms of the possible behaviour of the bubbles that have generated mixing of material before emplacement

Effects of an Unusual Poison Identify a Lifespan Role for Topoisomerase 2 in Saccharomyces Cerevisiae

A progressive loss of genome maintenance has been implicated as both a cause and consequence of aging. Here we present evidence supporting the hypothesis that an age-associated decay in genome maintenance promotes aging in Saccharomyces cerevisiae (yeast) due to an inability to sense or repair DNA damage by topoisomerase 2 (yTop2). We describe the characterization of LS1, identified in a high throughput screen for small molecules that shorten the replicative lifespan of yeast. LS1 accelerates aging without affecting proliferative growth or viability. Genetic and biochemical criteria reveal LS1 to be a weak Top2 poison. Top2 poisons induce the accumulation of covalent Top2-linked DNA double strand breaks that, if left unrepaired, lead to genome instability and death. LS1 is toxic to cells deficient in homologous recombination, suggesting that the damage it induces is normally mitigated by genome maintenance systems. The essential roles of yTop2 in proliferating cells may come with a fitness trade-off in older cells that are less able to sense or repair yTop2-mediated DNA damage. Consistent with this idea, cells live longer when yTop2 expression levels are reduced. These results identify intrinsic yTop2-mediated DNA damage as a potentially manageable cause of aging

Parents and GPs’ understandings and beliefs about food allergy testing in children with eczema:qualitative interview study within the Trial of Eczema allergy Screening Tests (TEST) feasibility trial

Aim To explore parent and general practitioner (GP) understanding and beliefs about food allergy testing for children with eczema.Design and setting Qualitative interview study in UK primary care within the Trial of Eczema allergy Screening Tests feasibility trial.Participants Semi-structured interviews with parents of children with eczema taking part in the feasibility study and GPs at practices hosting the study.Results 21 parents and 11 GPs were interviewed. Parents discussed a range of potential causes for eczema, including a role for food allergy. They believed allergy testing to be beneficial as it could potentially identify a cure or help reduce symptoms and they found negative tests reassuring, suggesting to them that no dietary changes were needed. GPs reported limited experience and uncertainty regarding food allergy in children with eczema. While some GPs believed referral for allergy testing could be appropriate, most were unclear about its utility. They thought it should be reserved for children with severe eczema or complex problems but wanted more information to advise parents and help guide decision making.Conclusions Parents’ motivations for allergy testing are driven by the desire to improve their child’s condition and exclude food allergy as a possible cause of symptoms. GPs are uncertain about the role of allergy testing and want more information about its usefulness to support parents and help inform decision making.Trial registration number ISRCTN15397185

Parents and GPs' understandings and beliefs about food allergy testing in children with eczema: Qualitative interview study within the Trial of Eczema allergy Screening Tests (TEST) feasibility trial

Aim To explore parent and general practitioner (GP) understanding and beliefs about food allergy testing for children with eczema. Design and setting Qualitative interview study in UK primary care within the Trial of Eczema allergy Screening Tests feasibility trial. Participants Semi-structured interviews with parents of children with eczema taking part in the feasibility study and GPs at practices hosting the study. Results 21 parents and 11 GPs were interviewed. Parents discussed a range of potential causes for eczema, including a role for food allergy. They believed allergy testing to be beneficial as it could potentially identify a cure or help reduce symptoms and they found negative tests reassuring, suggesting to them that no dietary changes were needed. GPs reported limited experience and uncertainty regarding food allergy in children with eczema. While some GPs believed referral for allergy testing could be appropriate, most were unclear about its utility. They thought it should be reserved for children with severe eczema or complex problems but wanted more information to advise parents and help guide decision making. Conclusions Parents' motivations for allergy testing are driven by the desire to improve their child's condition and exclude food allergy as a possible cause of symptoms. GPs are uncertain about the role of allergy testing and want more information about its usefulness to support parents and help inform decision making

Test‐guided dietary management of eczema in children: A randomized controlled feasibility trial (TEST)

BackgroundParents commonly ask about food allergy tests, to find a cause for their child's eczema, yet the value of routine testing is uncertain.ObjectiveTo determine whether a clinical trial comparing test‐guided dietary advice versus usual care, for the management of eczema, is feasible.MethodsChildren (>3 months and [less than] 5 years) with mild‐to‐severe eczema, recruited via primary care, were individually randomized (1:1) to intervention or usual care. Intervention participants underwent structured allergy history and skin prick tests (SPT) with dietary advice for cow's milk, hen's egg, wheat, peanut, cashew and codfish. All participants were followed up for 24 weeks. A sample of doctors and parents was interviewed. Registration ISRCTN15397185.ResultsFrom 1059 invitation letters sent to carers of potentially eligible children, 84 were randomized (42 per group) with mean age of 32.4 months (SD 13.9) and POEM of 8.7 (4.8). Of the 42, 6 (14%) intervention participants were advised to exclude one or more foods, most commonly egg, peanut or milk. By participant, 1/6 had an oral food challenge (negative); 3/6 were told to exclude until review in allergy clinic; and 6/6 advised a home dietary trial (exclusion and reintroduction of food over 4–6 weeks) – with 1/6 partially completing it. Participant retention (four withdrawals) and data completeness (74%–100%) were acceptable and contamination low (two usual care participants had allergy tests). There were three minor SPT‐related adverse events. During follow‐up, 12 intervention and 8 usual care participants had minor, unrelated adverse events plus one unrelated hospital admission.ConclusionsIt is possible to recruit, randomize and retain children with eczema from primary care into a trial of food allergy screening and to collect the outcomes of interest. Changes to recruitment and inclusion criteria are needed in a definitive trial, to ensure inclusion of younger children from more diverse backgrounds