University of Maryland, Baltimore County
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On the Use of Context and Policies in Declarative Networked Systems
No full textManaging complex networks while ensuring that certain high level goals such as security are met is a complicated process. This is evidenced by the recent Internet outages caused by operators misconfiguring BGP routers. Clearly, there is a growing need to separate the high level goals/policies from the low level mechanisms that implement the various services. We propose a declarative framework for specifying and enforcing high level policies in networks. The declarative framework offers flexibility in terms of specifying the higher level goals rather than focusing on the lower level mechanisms employed in the implementation, and robustness in terms of recovering from failure. One of the key building blocks of our framework is to allow applications to expose their semantics, thereby allowing the underlying network to exploit the semantics and provide better-than-best-effort service where possible. Our framework employs semantic web languages such as OWL and RDF to formally express application and network specifications, and thereby leverages the inherent reasoning and conflict resolution capabilities of these languages. Once the applications and networks are formally specified in our framework, operators can write adaptation policies to jointly adapt the application and network layers in response to changing network conditions. We demonstrate our approach by applying it to a variety of diverse problems in network configuration and management. Our experiments with video over wireless show that the joint adaptation provides higher performance compared to no adaptation as well as application/network layer alone adaptation. Furthermore, the adaptation policies are easy to express in our framework and can be dynamically changed at run time. We also show how our framework can be used to automatically configure BGP routers. High level organizational routing policies can be captured in our framework through appropriate ontological specifications. These specifications which can then be checked for correctness are automatically compiled into appropriate low level BGP configurations by our framework and installed on the routers. Furthermore, the logical basis of our specifications enables reasoning, and routers can engage in an argumentation with their neighbors to diagnose and recover from routing misconfigurations through policy controlled reconfigurations. In cases where the argumentation protocol does not converge or the reconfiguration needed is not permitted by policy, the network administrator is alerted along with a log of the argumentation protocol executed so far, helping in isolating the location and cause of failure
TOWARDS A FRAMEWORK FOR COLLABORATIVE INFORMATION EXCHANGE: EXPLORING EFFECTS OF TIME PRESSURE AND TASK DIFFICULTY ON GROUP COGNITION BEHAVIORS AND IMPLICATIONS FOR COMPUTER SUPPORTED COLLABORATION IN HEALTHCARE
No full textIn this information age, computerization in the healthcare workplace aims to improve quality of care, reduce administrative and clinical costs, and enhance healthcare work processes. However, integration in this environment proves challenging. Computerizing healthcare processes is not merely a technological pursuit but relies on human-driven coordination of highly fluid, uncertain, and exception-filled activities and processes spanning social, technological, and political boundaries. This dissertation aims to increase our understanding of the information arena framework in the context of shared and personal information spaces in team collaboration through a mixed qualitative-quantitative approach. A stage support model for classifying, measuring, and analyzing information exchange contexts in shared frontstage and personal backstage workspaces emerges. An experimental method that integrates qualitative classification of group information exchanges with quantitative task-timing of a collaborative folding task is proposed, and the effects of task difficulty and time pressure on information exchange behaviors are explored. Findings reveal measurable effects on information seeking behaviors in the shared and personal workspaces. The data suggest that amount and frequency of frontstage activity are sensitive to time pressure and task difficulty under certain situations. Time pressure and task difficulty are also shown to influence group information exchange behaviors. Time pressure increases goals planning, synchronized folding, and instruction confirmation activity, while high task difficulty decreases individual activity and increases group confusion and uncertainty but also encourages more instruction and demonstration. Significant within-information exchange mode effects are also uncovered. While stage support measurements yield interesting quantitative insights and reaffirm some findings of past studies, task specific findings are not readily generalized to all collaboration information exchange settings and demands continued research. This dissertation demonstrates the viability of a robust, novel methodology for data collection and analysis to quantify group processes in collaboration tasks and successfully employs pre-specification of task quality to minimize confounding process performance effects such as variable outcome quality. It also highlights the enormous potential for information, workspace, and collaboration research and design approaches to improve provider-provider and patient-provider interactions in healthcare settings and other collaborative, information rich settings where rapid and fluid information exchange is held under high safety and performance demands
The Passengers of the Ship Gilbert in 1721: British Female Convict Transportation from London to Annapolis
No full textABSTRACT Title of Document: THE PASSENGERS OF THE SHIP GILBERT IN 1721: BRITISH FEMALE CONVICT TRANSPORTATION FROM LONDON TO ANNAPOLIS. Teresa Bass Foster M.A. Historical Studies, 2011 Directed by Dr. Marjoleine Kars Associate Professor, History Department This thesis examines the experience of eighteenth-century convict women as part of a system of bond slavery in British colonial America. Throughout most of the eighteenth-century, convict women were regularly shipped from London to the British Chesapeake colonies. Transported from Newgate Prison aboard ships owned by London merchants, convict women endured a middle passage, often in a ship that previously plied African slave routes. Sold to Maryland planters, these women became bond slaves for a fixed term of seven to fourteen years, during which time their labor, productive and reproductive, was the sole property of a master/owner. I argue that the conditions of bond slavery differed for male and female convicts by examining individual and group experiences of the convicts aboard a representative ship, the Gilbert in 1721. This study will contribute to a sparse body of historical knowledge on the convict experience, one that often assumes a male normative subject in spite of the presence of women aboard every transport. Tens of thousands of male and female convicts were transported to the Chesapeake colonies, most destined for Maryland, and yet we know little about their lives. This paper expands upon the work of historians who have argued for the importance of colonial convict studies and it discusses the actual convict experience as an example of the multiplicity of slaveries present in British colonial America. Research methodology included eighteenth-century records at the Maryland State Archive, London Metropolitan Archives, and National Archives at Kew
Combined Heat and Power in Automobiles: Utilization of Waste Engine Heat to Drive Ethanol/Water Distillation
No full textThe production of ethanol from corn is currently an energy intensive process and provides a marginal energy investment return. The final steps of ethanol purification involve distillation and dehydration, together consuming the most energy in the ethanol production process. The most practical way to reduce this energy requirement is to reduce the distillation requirement at the manufacturing level. This can be realized by the use of combined heat and power technology, in which ethanol is used as the primary fuel in an engine and provides energy to do both mechanical work and heat energy to drive the distillation of an aqueous ethanol mixture. The net energy value is the energy released from combustion divided by the energy required to create the fuel. Given a startup amount of ethanol is present, it is possible to raise the net energy value of ethanol from 1.08 to 3.78 if distillation at the manufacturing level ceases at 50% v/v purity. The goal of this study was to investigate the feasibility of a system described as such by build a functioning proof of concept. In doing so, waste exhaust heat from a small Honda generator set was successfully captured to drive an ethanol/water distillation column capable of producing ethanol at 90% v/v purity. Further development is pending on resolving scale-up issues and running the generator set on 90% v/v ethanol to fully close the loop and realize the full potential of the combined heat and power system
Privacy Preserving Data Mining for Medical Data
No full textPrivacy has always been a great concern of patients and medical service providers. As a result of the recent advances in Information Technology and the government's push for Electronic Health Record (EHR) systems, a large amount of data is collected and stored electronically. This data is an important and rich source for research and needs to be made available for mining, while at the same time patient privacy needs to be preserved. The management of medical data is heavily regulated by the Health Insurance Portability and Accountability Act (HIPAA) in the United States. This strong level of oversight and inherent characteristics of medical data make Privacy Preserving Medical Data Mining a special field of Privacy Preserving Data Mining (PPDM). Yet, research is quite limited in this field. This study pinpoints the following gaps in current research: 1. Privacy protection in the medical field means the protection of individuals from being associated with undesirable conditions, diagnoses or treatments (Sensitive Attributes). Most existing research only considers datasets with a single sensitive attribute, while most medical datasets contain multiple sensitive attributes (e.g., site, stage and histology of cancer). As a result, some well known privacy protection models such as L-diversity cannot be directly applied to such datasets. 2. Although medical researchers often describe their research plans when they request anonymized data, most existing PPDM methods do not use this information when de-identifying the data. As a result, the anonymized data may not be very useful for the planned mining task. This study investigates utility-based privacy protection techniques to address this problem. Our goal is to improve the utility of the anonymized data for statistical analyses that are frequently used in medical research, such as linear and logistic regression, proportional hazards model and classification. Our technique improves a popular privacy protection method called condensation such that the improved method will lead to de-identified datasets with more utility while the privacy in the transformed data is preserved. Our methods are tested and validated on real cancer surveillance data provided by the Kentucky Cancer Registry
A Numerical Model to Predict Contact Resistance During Contact Solidification in a Ribbon Growth on Substrate Process
No full textThe role of photovoltaics in the energy industry has become well known over the course of the past decade. One new method of manufacturing silicon solar cells is using the ribbon growth on substrate process (RGS). The contact resistance between the silicon and the substrate plays a critical role in the efficiency of the silicon wafer. A model for prediction the contact resistance at the solid-liquid interface for RGS process is created based on a discrete surface model and heat transfer model. The effect of radiation on the contact resistance is quantified for various surface and material properties and operational conditions. The model result without radiation is found to be consistent those obtained through analytical experimental study. Radiation is found to increase the heat transfer for substrates of rough surface and low thermal conductivity. Other parameters such as surface emissivity, melt temperature, and substrate temperature are also studied. It is found that these parameters have a moderate effect on the heat transfer coefficient. On the other hand, substrate surface roughness and thermal conductivity are prominent factors in heat transfer at the interface. A full model of RGS process is used to characterize the effect of contact resistance on the heat removed from the interface by the substrate. For typical surface and material properties, contact resistance is able to cause a substantial temperature drop at the solid-liquid interface. The effect of contact resistance on heat transfer at the interface for substrates of different materials and different pulling rates is also studied
Uniform Approximation Property of Implicit Methods for a Stiff Family of Differential Equations
No full textStiff systems are characterized by the presence of multiple time scales where the fast scales are stable. The presence of a scaling factor, λ, in the system creates slow and fast components which lead to the distinct time scales. Conventional stability analysis shows that numerical solutions using explicit Taylor methods need a step size that is smaller than the fast time scale to get a stable solution. With implicit Taylor methods, the step size can be larger in comparison without affecting the stability of the solution. Most of the analysis done in regard to stiff systems tends to fix the step size and look at the stability of the numerical solution as the number of steps goes to infinity. This thesis presents a new form of analysis for numerical methods for stiff systems. We examine the numerical solutions over a finite time interval as the step size goes to zero over an entire range of the scaling factors λ≥1. We show that uniform convergence is a better indicator than unconditional stability for the effectiveness of a numerical solution to a stiff system. We investigate the uniform convergence of the numerical solutions to the true solution for a family of systems. We begin with an analysis of a family of scalar linear real equations to show that explicit Euler and trapezoidal methods are not uniformly convergent. Using Dini's theorem, we can show that the numerical solution using an implicit Taylor's method converges uniformly to the true solution as the step size decreases. In addition, we were able to show that when using the implicit Euler method, the uniform convergence is of the order O(h) where h is the step size. We then extend the results to higher dimensions to show that for a family of linear non-stiff systems, the explicit and implicit Euler converge uniformly. In addition, we show that the implicit Euler method converges uniformly for a family of stiff two-dimensional linear systems
Approximation of Nonintegral Frequency Moments
No full textLet a data stream have length m over an alphabet of n letters, with letter i occurring m_i times for i = 1,...,n: For any k, define the frequency moments F_k as F_k =sum_{i=1}^n m_i^k. Alon, Matias, and Szegedy in 1999 showed how to estimate F_k for an integer k>=2; with a one-pass algorithm using O(n^{1-1/k} log(n)) space for given length m; accuracy, and confidence. Here we extend those results to non-integral k; obtaining bounds on the variance giving accuracy and confidence estimates, and giving quantitative results on the algorithm's space requirements, with particular interest to when k is near 1. We also give some performance statistics of the algorithm for these cases, considering an application to entropy estimation. This algorithm of AMS is known as a sketching algorithm. Sketching algorithms are probabilistic algorithms generally requiring sublinear space vs. a classical O(n) (linear) space requirement, and may have applications for anomaly detection of systems or networks
Mothers' Psychosocial Functioning, Parenting, and Medical Decision Making Related to Children's Food Allergies and Food Challenges
No full textParents of children with food allergy are typically responsible for food allergy management and report that their child's condition impacts multiple aspects of family life Children with food allergy may undergo graded food challenges in a medical setting to determine if they can safely introduce the food back into their diet. The purpose of this study was to examine the impact of food allergy on mothers' psychosocial functioning and parenting as well as to determine if it was possible to predict which mothers are most likely to decide not to undergo a food challenge. Seventy mothers of children with food allergy provided data regarding their feeling about their child's food allergy and food challenges. The primary hypotheses were not supported. However, this study revealed that mothers may be willing to endure an anxiety-provoking situation in order to eliminate future anxiety about allergic reactions, especially when they trust their physician will appropriately care for their children. This study also indicated that food challenges have a profound impact on mothers' anxiety about their children having allergic reactions in the future. Furthermore, mothers with a high education level tend to perceive a greater impact of food allergy on their daily lives than mothers with a low education level. Additional research should be conducted in order to further our understanding of the psychological aspects of food allergy and food challenges and to guide clinicians in their care of children with food allergy
Virtual Reality Enhanced Videogame Distraction in Children Undergoing Cold Pressor Pain: The Role of Coping Style and Coping Strategies
No full textThis study sought to evaluate the effectiveness of virtual reality (VR) videogame distraction for children experiencing acute pain and clarify the role of coping style and pain coping strategies as moderators of VR distraction effectiveness. Sixty-two children (6-13 years old) underwent a baseline cold pressor trial followed by two cold pressor trials in which interactive videogame distraction was delivered with or without a VR helmet in counterbalanced order. As predicted, children demonstrated significant improvement in pain tolerance during both distraction conditions. However, there were no differences in pain tolerance between the distraction conditions. Neither coping style nor pain coping strategies moderated children's responses to distraction. Distraction was effective for both avoiders and approachers