Parameter search in an agent-based model of pedestrian movement in retail environments

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 105-107).Parameter search in an agent-based model of pedestrian movement in retail environments is part of a research effort by data-driven architecture in the Cognitive Machine Group at the MIT Media Lab. The approach pursued in this thesis is agent-based modeling, with an ultimate goal to use generative behaviors in agents to study effects of architectural and managerial decisions on retail environments. In this thesis, I designed and implemented an agent training module as a part of a software system which simulates and learns patterns of human pedestrian movement in retail environments. This thesis covers two different components: (1) the implementation of a hill-climbing training module and (2) a pedestrian path comparison metric. To measure the module's performance, the system is tested against video sequences collected from the actual retail environment.by Thananat Jitapunkul.M.Eng

DIGOXIN TOXICITY IN THAI MEDICAL PATIENTS : CLINICAL MANIFESTATIONS AND AN APPROPRIATE DIAGNOSTIC SERUM LEVEL

Abstract. This study considers the clinical manifestations and risk factors of digoxin toxicity and establishes an appropriate cut-off serum level for the diagnosis of toxicity. A retrospective study of 125 hospitalized patients whose serum digoxin was assayed in 1998 was conducted. Of the 125 subjects, 42 (33.6%) were classified as having definite digoxin toxicity, 9 (7.2%) were classified as having probable digoxin toxicity, and 74 (59.2%) were classified as non-toxicated. Of the patients with definite digoxin toxicity, 24 (57.1%) had cardiac manifestations, seven (16.7%) had non-cardiac manifestations, and 11 had manifestations of both types. The commonest manifestation was atrial fibrillation with block. Average daily doses of digoxin in the patients with definite digoxin toxicity and those without intoxication varied from 0.125 to 0.5 ng/ml. There was no significant statistical difference in digoxin dosage between those with and those without digoxin toxicity. Seven univariate factors of digoxin toxicity were examined: logistic regression analysis showed that, serum BUN and serum chloride were independent associated factors of digoxin toxicity: the finding suggests that renal impairment and volume contraction are strong determinants of digoxin toxicity. Mean (SD) serum digoxin levels among the patients with and without toxicity were 2.28 (1.3) and 1.05 (0.6) ng/ml respectively (p = 0.000). The best cut-off level determined by Receiver Operating Characteristic (ROC) analysis was 1.97 ng/ml. However, a low sensitivity and a high specificity make serum digoxin levels a diagnostic rather than a screening tool. The manifestations of digoxin toxicity among Thai inpatients are no different from those of other populations. The best cut-off level of serum digoxin for the diagnosis of toxicity is 2 ng/ml

An investigation of factors associated with the health and well-being of HIV-infected or HIV-affected older people in rural South Africa

BackgroundDespite the severe impact of HIV in sub-Saharan Africa, the health of older people aged 50+ is often overlooked owing to the dearth of data on the direct and indirect effects of HIV on older people's health status and well-being. The aim of this study was to examine correlates of health and well-being of HIV-infected older people relative to HIV-affected people in rural South Africa, defined as participants with an HIV-infected or death of an adult child due to HIV-related cause. MethodsData were collected within the Africa Centre surveillance area using instruments adapted from the World Health Organization (WHO) Study on global AGEing and adult health (SAGE). A stratified random sample of 422 people aged 50+ participated. We compared the health correlates of HIV-infected to HIV-affected participants using ordered logistic regressions. Health status was measured using three instruments: disability index, quality of life and composite health score. ResultsMedian age of the sample was 60 years (range 50-94). Women HIV-infected (aOR 0.15, 95% confidence interval (CI) 0.08-0.29) and HIV-affected (aOR 0.20, 95% CI 0.08-0.50), were significantly less likely than men to be in good functional ability. Women's adjusted odds of being in good overall health state were similarly lower than men's; while income and household wealth status were stronger correlates of quality of life. HIV-infected participants reported better functional ability, quality of life and overall health state than HIV-affected participants. Discussion and Conclusions The enhanced healthcare received as part of anti-retroviral treatment as well as the considerable resources devoted to HIV care appear to benefit the overall well-being of HIV-infected older people; whereas similar resources have not been devoted to the general health needs of HIV uninfected older people. Given increasing numbers of older people, policy and programme interventions are urgently needed to holistically meet the health and well-being needs of older people beyond the HIV-related care system. <br/

Pilot case-control investigation of risk factors for hip fractures in the urban Indian population

<p>Abstract</p> <p>Background</p> <p>Despite the reported high prevalence of osteoporosis in India, there have been no previous studies examining the risk factors for hip fracture in the Indian population.</p> <p>Methods</p> <p>We carried out a case control investigation comprising 100 case subjects (57 women and 43 men) admitted with a first hip fracture into one of three hospitals across New Delhi. The 100 controls were age and sex matched subjects who were either healthy visitors not related to the case patients or hospital staff. Information from all subjects was obtained through a questionnaire based interview.</p> <p>Results</p> <p>There was a significant increase in the number of cases of hip fracture with increasing age. There were significantly more women (57%) than men (43%). Univariate analysis identified protective effects for increased activity, exercise, calcium and vitamin supplements, almonds, fish, paneer (cottage cheese), curd (plain yogurt), and milk. However, tea and other caffeinated beverages were significant risk factors. In women, hormone/estrogen therapy appeared to have a marginal protective effect. For all cases, decreased agility, visual impairment, long term medications, chronic illnesses increased the risk of hip fracture. The multivariate analysis confirmed a protective effect of increased activity and also showed a decrease in hip fracture risk with increasing body mass index (odds ratio (OR) 0.024, 95% confidence interval (CI) 0.006-0.10 & OR 0.81, 95% CI 0.68-0.97 respectively). Individuals who take calcium supplements have a decreased risk of hip fracture (OR 0.076; CI 0.017-0.340), as do individuals who eat fish (OR 0.094; CI 0.020-0.431), and those who eat paneer (OR 0.152; 0.031-0.741). Tea drinkers have a higher risk of hip fracture (OR 22.8; 95% CI 3.73-139.43). Difficulty in getting up from a chair also appears to be an important risk factor for hip fractures (OR 14.53; 95% CI 3.86-54.23).</p> <p>Conclusions</p> <p>In the urban Indian population, dietary calcium, vitamin D, increased body mass index, and higher activity levels have a significant protective effect on hip fracture. On the other hand, caffeine intake and decreased agility increase the risk of hip fracture. Future studies should be done in order to direct primary preventive programs for hip fracture in India.</p

The impact of early emergency department allied health intervention on admission rates in older people: a non-randomized clinical study

<p>Abstract</p> <p>Background</p> <p>This study sought to determine whether early allied health intervention by a dedicated Emergency Department (ED) based team, occurring before or in parallel with medical assessment, reduces hospital admission rates amongst older patients presenting with one of ten index problems.</p> <p>Methods</p> <p>A prospective non-randomized trial in patients aged sixty five and over, conducted in two Australian hospital EDs. Intervention group patients, receiving early comprehensive allied health input, were compared to patients that received no allied health assessment. Propensity score matching was used to compare the two groups due to the non-randomized nature of the study. The primary outcome was admission to an inpatient hospital bed from the ED.</p> <p>Results</p> <p>Of five thousand two hundred and sixty five patients in the trial, 3165 were in the intervention group. The admission rate in the intervention group was 72.0% compared to 74.4% in the control group. Using propensity score probabilities of being assigned to either group in a conditional logistic regression model, this difference was of borderline statistical significance (<it>p </it>= 0.046, OR 0.88 (0.76-1.00)). On subgroup analysis the admission rate in patients with musculoskeletal symptoms and angina pectoris was less for those who received allied health intervention versus those who did not. This difference was significant.</p> <p>Conclusions</p> <p>Early allied health intervention in the ED has a significant but modest impact on admission rates in older patients. The effect appears to be limited to a small number of common presenting problems.</p

Epidemiology and outcomes of people with dementia, delirium and unspecified cognitive impairment in the general hospital: prospective cohort study of 10,014 admissions

Background&nbsp; Cognitive impairment of various kinds is common in older people admitted to hospital, but previous research has usually focused on single conditions in highly-selected groups and has rarely examined associations with outcomes. This study examined prevalence and outcomes of cognitive impairment in a large unselected cohort of people aged 65+ with an emergency medical admission.&nbsp; Methods&nbsp; Between January 1, 2012, and June 30, 2013, admissions to a single general hospital acute medical unit aged 65+ underwent a structured specialist nurse assessment (n = 10,014). We defined &lsquo;cognitive spectrum disorder&rsquo; (CSD) as any combination of delirium, known dementia, or Abbreviated Mental Test (AMT) score &lt; 8/10. Routine data for length of stay (LOS), mortality, and readmission were linked to examine associations with outcomes.&nbsp; Results&nbsp; A CSD was present in 38.5% of all patients admitted aged over 65, and in more than half of those aged over 85. Overall, 16.7% of older people admitted had delirium alone, 7.9% delirium superimposed on known dementia, 9.4% known dementia alone, and 4.5% unspecified cognitive impairment (AMT score &lt; 8/10, no delirium, no known dementia). Of those with known dementia, 45.8% had delirium superimposed. Outcomes were worse in those with CSD compared to those without &ndash; LOS 25.0 vs. 11.8 days, 30-day mortality 13.6% vs. 9.0%, 1-year mortality 40.0% vs. 26.0%, 1-year death or readmission 62.4% vs. 51.5% (allP &lt; 0.01). There was relatively little difference by CSD type, although people with delirium superimposed on dementia had the longest LOS, and people with dementia the worst mortality at 1 year.&nbsp; Conclusions&nbsp; CSD is common in older inpatients and associated with considerably worse outcomes, with little variation between different types of CSD. Healthcare systems should systematically identify and develop care pathways for older people with CSD admitted as medical emergencies, and avoid only focusing on condition-specific pathways such as those for dementia or delirium alone

Sex and the city: Differences in disease- and disability-free life years, and active community participation of elderly men and women in 7 cities in Latin America and the Caribbean

<p>Abstract</p> <p>Background</p> <p>The world's population is ageing, and four of the top 10 most rapidly ageing developing nations are from the region of Latin America and the Caribbean (LAC).</p> <p>Although an ageing population heralds likely increases in chronic disease, disability-related dependence, and economic burden, the societal contribution of the chronically ill or those with disability is not often measured.</p> <p>Methods</p> <p>We calculated country-specific prevalences of 'disability' (difficulty with at least one activity of daily living), 'disease' and 'co-morbidity' (presence of at least one, and at least two, of seven chronic diseases/conditions, respectively), and 'active community engagement' (using five levels of community participation, from less than weekly community contact to voluntary or paid work) in seven LAC cities. We estimated remaining life expectancy (LE) with and without disability, disease and co-morbidity, and investigated age, sex, and regional variations in disability-free LE. Finally, we modeled the association of disease, co-morbidity and disability with active community participation using an ordinal regression model, adjusted for depression.</p> <p>Results</p> <p>Overall, 77% of the LAC elderly had at least one chronic disease/condition, 44% had co-morbidity and 19% had a disability. The proportion of disability-free LE declined between the youngest (60–64 years) and the eldest (90 years and over) age-groups for both men (from 85% to 55%) and women (from 75% to 45%). Disease-free and co-morbidity-free LE, however, remained at approximately 30% and 62%, respectively, for men (20% and 48% for women), until 80–84 years of age, then increased. Only Bridgetown's participants had statistically significantly longer disability-free LE than the regional average (IRR = 1.08; 95%CI 1.05–1.10; p < 0.001). Only Santiago's participants had disability-free LE which was shorter than the regional average (IRR = 0.94; 95%CI 0.92–0.97; p < 0.001). There was 75% active community participation overall, with more women than men involved in active help (49% vs 32%, respectively) and more men involved in voluntary/paid work (46% vs 25%, respectively). There was either no, or borderline significance in the association between having one or more diseases/conditions and active community engagement for both sexes. These associations were limited by depression (odds ratio [OR] reduced by 15–17% for men, and by 8–11% for women), and only remained statistically significant in men. However, disability remained statistically significantly associated with less community engagement after adjusting for depression (OR = 0.58, 95%CI 0.49–0.69, p < 0.001 for women and OR = 0.50, 95%CI 0.47–0.65, p < 0.001 for men).</p> <p>Conclusion</p> <p>There is an increasing burden of disease and disability with older age across the LAC region. As these nations cope with resulting social and economic demands, governments and civic societies must continue to develop and maintain opportunities for community participation by this increasingly frail, but actively engaged group.</p

Estimates of Outcomes Up to Ten Years after Stroke: Analysis from the Prospective South London Stroke Register

Charles Wolfe and colleagues collected data from the South London Stroke Register on 3,373 first strokes registered between 1995 and 2006 and showed that between 20% and 30% of survivors have poor outcomes up to 10 years after stroke

Evaluation of the Frails' Fall Efficacy by Comparing Treatments (EFFECT) on reducing fall and fear of fall in moderately frail older adults: study protocol for a randomised control trial

<p>Abstract</p> <p>Background</p> <p>Falls are common in frail older adults and often result in injuries and hospitalisation. The Nintendo^®Wii™ is an easily available exercise modality in the community which has been shown to improve lower limb strength and balance. However, not much is known on the effectiveness of the Nintendo^®Wii™ to improve fall efficacy and reduce falls in a moderately frail older adult. Fall efficacy is the measure of fear of falling in performing various daily activities. Fear contributes to avoidance of activities and functional decline.</p> <p>Methods</p> <p>This randomised active-control trial is a comparison between the Nintendo WiiActive programme against standard gym-based rehabilitation of the older population. Eighty subjects aged above 60, fallers and non-fallers, will be recruited from the hospital outpatient clinic. The primary outcome measure is the Modified Falls Efficacy Scale and the secondary outcome measures are self-reported falls, quadriceps strength, walking agility, dynamic balance and quality of life assessments.</p> <p>Discussions</p> <p>The study is the first randomised control trial using the Nintendo Wii as a rehabilitation modality investigating a change in fall efficacy and self-reported falls. Longitudinally, the study will investigate if the interventions can successfully reduce falls and analyse the cost-effectiveness of the programme.</p> <p>Trial registration</p> <p>Australia and New Zealand Clinical Trials Register (ANZCTR): <a href="http://www.anzctr.org.au/ACTRN12610000576022.aspx">ACTRN12610000576022</a></p