Strain rate effects on the behavior of shape memory alloys

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2013.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (p. 29-30).by Amanda Olender.S.B

Avila Beach: From Funky to Fabulous

Among California’s coastal communities, Avila beach may be the one most defined by its history. Amanda Ross discusses the unique planning and redevelopment process there, starting with the cleanup of a decades-long crude oil spill that had contaminated the soil and led to the reconstruction of its beach and the entire historic downtown. This article reflects part of the activities for Professor Paul Wack’s Plan Implementation graduate class in 2015

Stochastic Models for the Consequences of Plasmodium Falciparum Infections in the Human Host: Malaria Morbidity, Mortality and Infectivity

The consequences of Plasmodium falciparum infections for humans range from selflimiting asymptomatic parasitaemia to rapid death. Annually, P. falciparum malaria is estimated to cause 0.5 billion acute febrile episodes, 2-3 million severe episodes warranting hospital admission and one million deaths. This enormous burden demands effective control strategies. A number of different interventions are available, but policy-makers need a rational basis for discriminating between them. The likely consequences of each intervention, or combination of interventions, must be considered. Trials can provide estimates of the impact of interventions on acute episodes over a short timespan. Predictions are required where field data are not available: over longer time periods, for severe outcomes, for many combinations of interventions, or for interventions which do not yet exist. A model intended for making quantitative predictions of the impact of interventions must relate transmission and infection to the key outcomes used by health-planners such as morbidity, mortality and cost-effectiveness. It must also allow for dynamic effects on transmission and acquired immunity, and incorporate the effect of the health system. Until recently, there was no such model. In the past, emphasis had lain with the transmission cycle. In addition, the most practical models would be individual-based with high computational demands. In response to this need, a stochastic individual-based integrated model has been developed at the Swiss Tropical Institute. The core of the integrated model is a description of asexual parasite densities, providing a basis for the effects of acquired immunity on reducing densities and for the density-based consequences of infection. This thesis contributes those elements that consider the immediate consequences of human infection: morbidity, mortality and transmission to the vector. The integrated model is then applied to questions concerning a new intervention, intermittent preventive treatment in infants (IPTi). A framework for morbidity and mortality is proposed. The probability of an acute febrile malaria episode is related to parasite densities via individual- and time-specific pyrogenic thresholds that respond dynamically to recent parasite load. Severe episodes result either from overwhelming parasitaemia, or from acute episodes in conjunction with a co-morbidity which acts to weaken the host. Both direct and indirect mortality were considered. Age-dependent case fatality rates estimated from field data were used to quantify the probability of direct mortality. Indirect deaths occur following an acute episode with subsequent co-morbidity after the parasites have cleared, or within the neonatal period as a consequence of maternal infection. Co-morbidity is assumed to be age-dependent. The model components are fitted to field data or to summaries of field data, and can simultaneously account for the observed age- and exposure-specific patterns of paediatric malaria and malaria-associated mortality. The model component for infectivity relates asexual parasite densities to the probability of infecting a feeding mosquito, taking into account the delay resulting from the timecourse of gametocytaemia and the need for both male and female gametocytes in the blood meal. This component is fitted to data from malariatherapy patients and can account for observed patterns of human infectivity. The integrated model is validated against published estimates of the contribution of different age groups to the infectious reservoir. The integrated model, in conjunction with an added component for the action of sulphadoxine-pyrimethamine (SP) and site-specific inputs, reproduced the pattern of results of the IPTi trials reasonably well. The model was modified to represent different hypotheses for the mechanism of IPTi. These hypotheses concerned the duration of action of SP, the empirical timing of episodes caused by individual infections, potential benefits of avoiding episodes on immunity and the effect of sub-therapeutic levels of SP on parasite dynamics. None of the modified versions improved the fit between the model predictions and observed data, suggesting that known features of malaria epidemiology together with site-specific inputs can account for the pattern of trial results. Predictions using the integrated model suggest that IPTi using SP is effective over a wide range of transmission intensities at reducing morbidity and mortality in infants. The predicted cumulative benefits were proportionately greater for mortality and severe episodes than for acute episodes, due to the age-dependent co-morbidity functions in the model. IPTi was predicted to avert a greater number of episodes where IPTi coverage was higher, the health system treatment coverage lower, and for drugs which were more efficacious and had longer prophylactic periods. Additionally, IPTi was predicted to have little impact on transmisison intensity. This is the first major attempt to model the dynamic effects of malaria transmsission, parasitological status, morbidity, mortality and cost-effectiveness using model components which were fitted to field data. The model can be extended to predict the dynamic effects of different interventions, and combinations of interventions. The ability to compare the likely impact of different interventions on the same platform will be a valuable resource for rational decisions about strategies to control the intolerable burden of malari

Friendship and psychosocial functioning in children who have sustained a traumatic brain injury

Objective: Traumatic brain injury (TBI) in children has previously been associated with theory of mind deficits and social problem solving difficulties; potentially interfering with psychosocial development and friendships. This study aimed to investigate if friendship quality, rates of loneliness and general psychosocial functioning are different in children who have sustained a traumatic brain injury (TBI) compared to non-injured controls. Design: A between subjects design with 14 participants in the TBI group and 14 in the non-injured control group, all aged between 7 and 13 years. The groups were matched for gender and were similar in age and socio-economic status. Methods: There were 5 outcome measures. Three were completed by children relating to receptive vocabulary (BPVS II), friendship quality (FQQ-R) and rates of loneliness (LSDS). Two were completed by the main caregiver measuring social skills deficits and social withdrawal (PIC-2) and general psychosocial and behavioural functioning (SDQ). Outcome and Results: The TBI group had more severe difficulties in hyperactivity (z = -3.5, p < 0.001) and emotional symptoms (z = -2.4, p< 0.05) than their non-injured peers. No significant differences were observed on measures of friendship quality; however, a larger percentage of the TBI group fell within the abnormal or borderline range in terms of peer problems. Conclusions: Whilst finding evidence of vulnerability in hyperactivity, emotional symptoms and conduct problems, evidence for friendship problems were not found in children following TBI. There is a need for prospective longitudinal research to explore the complex relationship between TBI and poorer social outcomes that are often apparent in adolescence

Why we may need to reconsider the current one-size fits all approach to US housing policy.

Every year, the US federal government spends billions on low-income rental housing assistance. But is it spending this money effectively by using housing vouchers? In new research using panel data from rental units, Michael Eriksen and Amanda Ross find that the effects of housing vouchers vary from city to city. Introducing vouchers can drive up rents by increasing the demand of those who receive them for higher quality rental housing, but decrease demand and thus rent for lower quality accommodation. They show higher rent increases occur in areas where housing supply is inelastic due to a lack of developable land suggesting alternative place-based housing policies may be more effective in those areas

Trams, Trials and Tribulations: the development of Cathedral Square, Christchurch 1900-18

Cathedral Square Christchurch is the city's premier urban space. Yet it is without doubt the most debated and controversial two and half hectares of urban design space in the city. Set out in the shape of cross rather than a square, the last five decades of the nineteenth century saw just as much controversy over its design and use as did the entire twentieth century and on into the beginnings of the twenty-first century. Over this time its design has been the butt of jokes, the subject of constant political debate and subject of many learned articles, seminars and conference papers. The period 1900 to 1918 was one of intensive design change as Christchurch moved into the era of electric trams, motor buses and motor cars. While handsome buildings grew on the square's perimeter during this period, in 1907 a less than attractive architecturally-designed transport shelter appeared in its centre causing architect Samuel Hurst Seager, a member of the Christchurch Beautifying Society, to describe it as a public building of "… appalling ugliness." Inspired by the title "Tramway Trials and Tribulations - the saga of the tramway shelter" this paper will examine the design issues surrounding Cathedral Square during the period 1900-1918 – a period that saw the first competition to improve the aesthetic reading of this space

Housing Vouchers and the Price of Rental Housing

Abstract. We estimate the effect of increasing the supply of housing vouchers on rents using a panel of units in the American Housing Survey. We do not find that an increase in vouchers affected the overall price of rental housing, but do estimate differences in effects based on an individual unit’s rent before the voucher expansion. Our results are consistent with voucher recipients renting more expensive units after receiving the subsidy. We also find the largest positive price increases for units in relatively supply inelastic cities, suggesting policy makers should take local attributes into account with targeting future housing subsidies