University of Maryland, Baltimore County
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Context-Aware Middleware for Activity Recognition
No full textSmart phones and other mobile devices have a simple notion of context largely restricted to temporal and spatial coordinates. Service providers and enterprise administrators can deploy systems incorporating activity and relations context to enhance the user experience, but this raises considerable collaboration, trust and privacy issues between different service providers. Our work is an initial step toward enabling devices themselves to represent, acquire and use a richer notion of context that includes functional and social aspects such as co-located social organizations, nearby devices and people, typical and inferred activities, and the roles people fill in them. We describe a system that learns to recognize richer contexts using sensor data from a person's Android phone along with annotations on her calendar and general background knowledge. Classifier models predict the individual users' context with respect to a mid-level detailed activity he is performing like `Listening a Talk', `Walking', `Sleeping', etc. We report on an evaluation of the individual and generic models in the University setting for predicting context
Clinical-Genomic Analysis for Disease Prediction
No full textRecent advances in genomic research have generated vast amounts of information that can help identify individuals who differ in their susceptibility to a particular disease or response to a specific treatment. This information may offer solutions for the treatment of complex chronic diseases that are influenced by a wide array of factors. This vast amount of information brings critical challenges in applying advanced technology to synthesize clinical-genomic patient data. Synthesizing this information is necessary to derive the knowledge that would empower physicians to provide personalized care with the best possible therapeutic interventions. We used statistical methods and data mining approaches to understand clinical-genomic risk factors that differentiate Type II Diabetes cases from healthy controls. We investigated whether inclusion of genomic risk factors in conjunction with clinical information improves classification accuracy. We also demonstrate how a biased and an unbiased method for selection of risk associated single nucleotide polymorphisms (SNPs) effect clustering along with clinical information. We determined the optimal method based on its clustering performance
Differential Bioavailability of Polychlorinated Biphenyls Associated with Anthropogenic and Natural Carbons
No full textPolychlorinated biphenyls (PCBs) are a class of persistent, bioaccumulative and toxic legacy contaminants found widespread in the environment. Although PCBs were banned in the United States in 1976, reservoirs of PCB-impacted sediments continue to pose risks to ecological and human health today. Sediments are heterogeneous mixtures of many different particle types, such as sand, clay, wood, detritus, coal, soot, and even plastic, and these different particles have varying capacity and affinity for sorbing hydrophobic organic contaminants which leads to PCBs being differentially bioavailable in different matrices. The dominant role of condensed, black carbon particles, such as coal or activated carbon (AC), to strongly sorb PCBs and limit bioavailability, both via aqueous and digestive pathways of exposure, is demonstrated in this body of work using both direct and surrogate measures of bioavailability. The primary objective of this research was to assess, in a 4-year long-term monitoring effort, the effectiveness of AC amendment in a freshwater river to reduce bioavailability of PCBs at the base of the aquatic food web, and to limit diffusive flux from sediments to the overlying water column. After treatment with AC applied at a dose similar to the native organic carbon of sediment, bioaccumulation in freshwater oligochaete worms measured in both laboratory and field exposures was reduced by 62-99% and concentrations of PCBs in water at equilibrium with the sediment was reduced by >95% compared to measurements with unamended background sediments in each year. Passive samplers showed that the chemical activities in pore waters of treated sediments were reduced in comparison to untreated sediments and the overlying water, indicating a lower potential for contaminant flux following AC amendment. Furthermore, it was observed that AC aged in sediments for several years in the field was still capable of sorbing additional HOCs, although sorption was attenuated in comparison to fresh AC addition. Overall, this research demonstrates that PCB exposure from moderately contaminated river sediments may be managed effectively through activated carbon amendment to sediments
Accurate Simulation of the Dynamics of Elevator Systems
No full textAccurate simulation of dynamics of elevator systems is important in addressing challenges in the design of elevators. This dissertation is dedicated to the methodologies and applications of the numerical simulation of the dynamics of elevator cable-car systems, pulley-cable systems, and traveling and compensation cables. A new spatial discretization and substructure method is developed to calculate the dynamic responses of one-dimensional systems, which consist of length-variant distributed-parameter components such as strings, rods, and beams, and lumped-parameter components such as point masses and rigid bodies. This methodology is used to study the longitudinal, transverse, and their coupled dynamics of moving elevator cable-car systems. There are complicated matching conditions between the cable and the car, which cannot be satisfied in traditional methods, but can be satisfied in the current method. Hence not only the displacements, but also the internal forces/moment, such as the axial force, the bending moment, and the shear force, which are related to the spatial derivatives of the longitudinal or transverse displacement, are accurately calculated. The longitudinal-transverse coupled vibrations of a moving cable-car system are also studied using this method, and the results are compared with those from the linear models. While the result from the linear model for the transverse vibration agrees well with that from the nonlinear coupled model, the axial force calculated from the linear model can significantly differ from that from the nonlinear model when the car approaches the top of the hoist way. It is found that a large slope in the transverse vibration can significantly increase the vibratory tension in the cable, and attenuate the safety of the system. These results can be explained by theoretical analysis and verified by the absolute nodal coordinate formulation. The methodology is also used in conjunction with a simple belt creep model to study the dynamics of pulley-cable systems. A nonlinear, planar model of a slack cable with bending stiffness and arbitrarily moving ends is developed, using the slope angle of the centroid line of the cable to describe the motion of the cable, and is applied to elevator traveling and compensation cables. It is found that a vertical motion of the car can introduce a horizontal vibration of a traveling or compensation cable. This model is more efficient than the finite element models as it uses a much smaller number of elements to reach the same accuracy. Moreover, based on the asymptotic analysis of this model, a computationally efficient, linear model is developed for calculating the natural frequencies, mode shapes, and dynamic responses of stationary elevator traveling and compensation cables. The linear cable model consists of two vertical cable segments connected by a half circular loop at the bottom. There is a good agreement between the predictions from the linear and nonlinear models and between the measured natural frequencies from a full-scale experiment and the corresponding calculated ones
Effectiveness of an Occupational Therapy Home Intervention to Increase Safety, Improve Function, and Reduce Falls Among At-Risk Community Dwelling Older Adults
No full textThe United States faces a growing population of older adults and accompanying disability, coupled with constrained public resources. Innovative policy solutions are needed that improve safety and quality of life for older adults in a cost-effective manner. A randomized controlled trial using a pre-test/post-test design assessed the effectiveness of a novel occupational therapy service involving customized in-home interventions conducted by highly trained therapists. The service reflects a decade of development and field testing to identify the essential elements of the evaluation and intervention process. Eligible individuals included at-risk, community-dwelling older adults who are currently receiving services from local area agencies on aging, have difficulty with some functional tasks but are able to move around within the home, and have the cognitive capacity to participate in the assessment and intervention. The treatment group received a baseline assessment followed by treatment, while the delayed treatment (control) group received a baseline assessment followed by no treatment. At three months, both groups were re-assessed. The data for 71 participants was provided by Howard and Montgomery Counties; complete data was available for 60 participants. The treatment and control groups were compared on baseline covariates; regression adjustments were made as necessary. Analysis utilized Ordinary Least Squares (OLS); model assumptions were tested using regression diagnostics. Significant improvements were found in home safety and quality of life, as were significant reductions in fear of falling. No improvements were found with respect to the other outcome measures. Results were robust to alternative specifications, robust standard errors, and the omission of outliers and influential observations. This study adds to the growing literature of occupational therapy interventions targeting at risk older adults to improve home safety, independence, and quality of life. The contribution of this study is a first step in shifting the design of services for at-risk, community-dwelling older adults. Components of the intervention training could be provided to staff involved in allocating services. If the funding mechanisms can shift away from the dependency model to a model that facilitates independence, older adults could potentially experience better quality of life, and services could be provided to an expanded population
Tau leap methods for stiff stochastic chemical systems
No full textTau leap methods enable efficient simulation of stochastic chemical systems. We develop new tau leap methods that consider the following issues: stiffness, fluid limit, integer-valued states, nonnegative states, and correlations among species. We propose two tau leap methods taking into account a compromise among these issues. Both tau leap methods have the implicit Euler as their fluid limit, which is accomplished by the use of a split step: the first part computes the mean update implicitly, and the second part generates a random update explicitly with the mean computed in the first part. The first tau leap method is designed to generate physically feasible population vectors yielding integer and nonnegative population states, and we refer to it as the Minkowski-Weyl tau (MW-tau) leap method. It incorporates the Minkowski-Weyl decomposition from polyhedral theory in generating nonnegative states, and three variants are proposed to reflect the idea of the method. The second method is devised to approximate the correlations among species, and it is called the tau leap method via local linear noise approximation (LLNA-tau). It utilizes the linear noise approximation (LNA) to obtain ODEs governing the evolution of the mean and the covariance for stochastic chemical systems. LLNA-tau applies LNA to approximate the mean and the covariance for reactions within one time step. The LNA is recalculated after each time step, and the population state is updated by Gaussian random variables with the approximated mean and covariance. Analysis of consistency, stability and fluid limit of the tau leap methods are also presented. We illustrate MW-tau and LLNA-tau by some numerical examples, and compare them with existing tau leap methods. For most cases, the MW-tau and LLNA-tau methods perform favorably
The experiences of male Afghan refugees in the United States, seen through the lens of Sarbin's social role theory
No full textMore than 3 million people have fled Afghanistan since the outbreak of armed warfare in the late `70's. Extant research with Afghan survivors of war highlights the combined effects of stressors related to war and subsequent migration. The current study uses Sarbin's (1970) social role theory as a framework for analyzing the experiences of seven Afghan men who migrated to the U.S. after fleeing war-torn Afghanistan. It emerged that the Afghan-American men in this sample developed a series of adaptive strategies in response to how they located themselves within the four ecologies theorized by Sarbin, namely self-maintenance (physical), social (relational), transcendental (meaning-making) and normative (internalized standards of success). Findings also revealed that experiences in both Afghanistan and the U.S. contributed to how this sample of Afghan men made meaning of their migration and facilitated their adaptation efforts as refugees
The Laramie Project (2011)
No full textPromotional materials produced for The Laramie Project, performed by the UMBC Theatre Department in November/December 2011. Includes playbill, program, and five publicity photographs.November 30-December 11, 201
