http://idea.library.drexel.edu iDEA is a centralized virtual space to access unique digital resources produced by the Drexel community. Search the Channel search http://idea.library.drexel.edu/simple-search http://idea.library.drexel.edu/handle/1860/2934 Title: RDM - relationship diagramming method <br/> <br/>Authors: Plotnick, Fredric Leigh <br/> <br/>Abstract: The Critical Path Method of Planning and Scheduling (CPM) was developed in the mid to late 1950s to improve upon the Gantt Chart or bar-chart, by using the recently developed digital computer to perform much of the tedium of the process. The methodology developed was therefore largely dependent upon and constrained by the limits of digital computers of that era, which initially lacked what is now called “random access memory.” The enhancement of adding RAM in the mid 1960s led to a variant in the original methodology. To make the distinction the original method was now named the Arrow Diagramming Method (ADM) variant, while the newer variant was named Precedence Diagramming Method (PDM.) However, due to the still limited computers of the 1960s, the methodology utilized for PDM was less rigorous than that theorized by leaders in the field. Commercialization of personal computers in the 1980s exacerbated these issues, as initial models had less capability than the large mainframe computers for which most software had previously been developed. In considering the industry application of CPM, a side effect of the dispersion and convenience of personal computing was that simplified software was mass marketed. Many individuals with lesser training and experience with CPM now have access to sophisticated scheduling software. Such individuals may unwittingly misuse the software and possibly obtain erroneous output. The further advancements in power and memory of desktop computers to the present day has largely been used to provide superior graphics, but not to resolve these issues, nor to provide additional functionality beyond that developed in the 1950s. The purpose of this research has been to revisit the simplifications of the developers of the 1950s, 1960s and 1980s, and then to develop a more robust and accurate methodology utilizing the capabilities of modern computers. This led to development of a third variant, named RDM (or Relationship Diagramming Method.) This dissertation discusses the problems related to the initial development of CPM, limitations of the ADM and PDM variant, and how these have been addressed using the new RDM variant. http://idea.library.drexel.edu/handle/1860/2933 Title: Direct plasma interaction with living tissue <br/> <br/>Authors: Fridman, Gregory <br/> <br/>Abstract: For some time, plasma has been used in medicine to cauterize or cut tissue using heat and mechanical energy. In the recent decade, some researchers around the world have started to investigate how gas jets that pass through thermal plasma can be employed in medicine. This thesis presents the first investigation of biomedical uses of non‐thermal plasma discharge which comes in direct contact with living tissue. It is demonstrated that the direct application of non‐thermal plasma in air can cause rapid deactivation of bacteria on surfaces of tissues without causing any visible tissue damage. Medical need for such a device is discussed. Construction and operation of various types of non‐thermal plasma power supplies and many types of treatment electrodes are presented as well. Application of this plasma to living organisms is shown to be safe from both the electrical perspective and from the biological perspective. Biological safety is revealed through a series of differential skin toxicity trials on human cadaver tissue, live hairless mouse skin tissue, live pig skin tissue, and finally in an open wound model on pigs. Direct non‐thermal plasma in air is shown to deactivate bacteria about 100 times faster than indirect application using jets. A series of experiments reveal that this effectiveness is due to the ability of direct discharge to bring charges to tissue surfaces. It is demonstrated that neither ultraviolet (UV) radiation nor neutral active species such as hydroxyl radicals or ozone produced in plasma are responsible for the main effect on bacteria. Although much additional work remains on establishing detailed mechanism by which charges from plasma achieve this effect, the work carried out in this thesis clearly demonstrates that direct application of non‐thermal plasma in air can be a very useful tool in medicine. http://idea.library.drexel.edu/handle/1860/2932 Title: Visual impairment in a visual medium perspectives of online learners with visual impairments <br/> <br/>Authors: Candido, Jacqueline P. <br/> <br/>Abstract: There is a lack of understanding about the experiences and perceptions of adults with visual impairments as they experience the visual medium of online learning. People with visual impairments experience the Internet differently from those with normal sight. As the Internet continues to grow as an educational approach, it is important to understand how this hidden population might use online learning to reach their educational goals. This phenomenological study explored the events and experiences that shaped the lives of three people with visual impairments in order to describe their perspectives of online learning. Phenomenological methodology was selected as the most effective way to illuminate the individual experiences of the participants. The research methods included in-depth interviews, observation over time, internet communication, and a reflection journal. The study was conducted over many months in order to follow the steps and voices of the participants. Their experiences, challenges and achievements have been portrayed from the perspective of the participants. The findings are reported using verbatim quotes from the participants, textural descriptions and a matrix depicting themes that emerged from the study. The implications from this study revealed that online learning is a viable option for people with visual impairments, but it can be constraining as well. Although the online strategy offers benefits such as convenience, flexibility and avoidance of transportation hassles, there can be obstacles such as compatibility with assistive technology. Recommendations for improvements are offered for online learners with visual impairments as well as for institutions and professors. Postsecondary schools and faculty offering online programs must be committed to serving the online learner and the new responsibilities this entails, such as increased use of email, phone and off-peak hours. Use of new technologies for enhanced communication and interaction could enable more students to succeed in online classes. Institutions must make it a priority to ensure that their online classes are accessible. Proposals are made for partnerships that could foster additional success for students with visual impairment in online courses. Ideas for future research as well as a personal closing from the researcher with insider knowledge conclude the study. http://idea.library.drexel.edu/handle/1860/2931 Title: Semantics-based language models for information retrieval and text mining <br/> <br/>Authors: Zhou, Xiaohua <br/> <br/>Abstract: The language modeling approach centers on the issue of estimating an accurate model by choosing appropriate language models as well as smoothing techniques. In the thesis, we propose a novel context-sensitive semantic smoothing method referred to as a topic signature language model. It extracts explicit topic signatures from a document and then statistically maps them into individual words in the vocabulary. In order to support the new language model, we developed two automated algorithms to extract multiword phrases and ontological concepts, respectively, and an EM-based algorithm to learn semantic mapping knowledge from co-occurrence data. The topic signature language model is applied to three applications: information retrieval, text classification, and text clustering. The evaluations on news collection and biomedical literature prove the effectiveness of the topic signature language model. In the experiment of information retrieval, the topic signature language model consistently outperforms the baseline two-stage language model as well as the context-insensitive semantic smoothing method in all configurations. It also beats the state-of-the-art Okapi models in all configurations. In the experiment of text classification, when the size of training documents is small, the Bayesian classifier with semantic smoothing not only outperforms the classifiers with background smoothing and Laplace smoothing, but it also beats the active learning classifiers and SVM classifiers. On the task of clustering, whether or not the dataset to cluster is small, the model-based k-means with semantic smoothing performs significantly better than both the model-based k-means with background smoothing and Laplace smoothing. It is also superior to the spherical k-means in terms of effectiveness. In addition, we empirically prove that, within the framework of topic signature language models, the semantic knowledge learned from one collection could be effectively applied to other collections. In the thesis, we also compare three types of topic signatures (i.e., words, multiword phrases, and ontological concepts), with respect to their effectiveness and efficiency for semantic smoothing. In general, it is more expensive to extract multiword phrases and ontological concepts than individual words, but semantic mapping based on multiword phrases and ontological concepts are more effective in handling data sparsity than on individual words. http://idea.library.drexel.edu/handle/1860/2930 Title: Why gender matters in CMC: gender differences in remote trust and performance with initial social activities <br/> <br/>Authors: Sun, Xiaoning <br/> <br/>Abstract: Gender effects in face-to-face and virtual communications are well known in the discipline of communication studies. However, less attention has been paid to the effects of gender on carrying out complex, collaborative tasks in virtual environments, mediated by modern communication media. The primary objective of this research is to explore gender differences in synchronous computer-mediated communication (CMC) with and without initial social activities. In particular, it aims to investigate whether exposure to pre-task social activities before doing a task can help males, who tend to be less trusting, overcome the trust barrier. This research combines theories and empirical findings from a wide range of disciplines, including CMC, gender, trust and communication. One hundred and twenty four participants who did not previously know each other were recruited to form homogeneous pairs, male-male and female-female. Each pair carried out a competitive task via Instant Messaging (IM), either with or without pre-task social chat. The results from both quantitative and qualitative analyses indicate that female pairs had high levels of trust and more collaborative behaviors than male pairs in doing the task. In addition, females’ collaborative conversational style focusing on harmonious relationships put them in a position to achieve trust in the communication. The results also suggest that initial social chat prior to beginning work helps remote team members build trust in the communication. But that initial social chat is more effective in female dominated groups. The results have implications for research and practice of establishing higher levels of trust among remote workers who have to communicate via low-end media. In addition, this research will add to the small, but growing body of literature on the effects of group gender composition on performance outcomes. It will also benefit designers understanding emoticon usage patterns and developing design criteria for creating usable and useful interactive chat systems that support trust of both genders. http://idea.library.drexel.edu/handle/1860/2929 Title: Arsenic removal effectiveness of iron oxide-based fibrous adsorbents and stability of granular iron oxide media <br/> <br/>Authors: Kumar, Arun <br/> <br/>Abstract: This study focuses on two objectives to improve arsenic adsorptive capacities of iron oxide-based adsorbents. The first objective was to improve arsenic removal effectiveness of iron oxide-based adsorbent by investigating the potential of four types of fibrous materials, polypropylene, polyester, fiberglass, and cellulose for their ability to retain iron coatings and to remove arsenate. Arsenate adsorption densities were highest for iron-oxide coated fiberglass and cellulose, suggesting that these fibrous materials may offer advantages over iron-oxide-coated sand. Arsenate mass-transfer was observed to be limited by the external mass-transfer resistance initially and intra-particle mass-transfer resistance subsequently, which could be improved by introducing additional reactive sites on the fibers surface. Further experiments are warranted to make these coated fibers, particularly iron-oxide-coated fiberglass fibers, competitive with other commercially available arsenic adsorbents. The second objective of this work was to understand the combined effects of near-neutral solution pH levels, ion types, and concentrations typical of an arsenic contaminated groundwater on phase transformation of an iron oxide-based media. Batch studies were conducted using a granular iron hydroxide media and combined effects of time, pH, and ions were studied by observing changes in mineralogy of media and extent of crystallinity of iron oxide media. No major iron oxide phase change was observed during the aging studies and arsenic and other ions were not observed to be introduced in the XRD spectra of different iron oxide samples. Initial solution pH and aging time appear to be the significant factors affecting the extent of crystallization of different iron oxide samples, and the extent of crystallinity was observed to increase with aging time and low solution pH. The extent of crystallization of iron oxide was observed to decrease for samples, aged in the presence of 0.3 mg/L ferrous iron ions and increase during the intermediate pH adjustment studies. Further research work is required to understand the effects of ferrous iron and arsenic ions at near-neutral solution pH at room temperature for longer periods (i.e., > 1 years) on the crystalline structure of the iron oxide media, and their influence on its overall adsorptive capacity. http://idea.library.drexel.edu/handle/1860/2928 Title: Facsimile intrusion systems over IP networks <br/> <br/>Authors: Dandekar, Anup <br/> <br/>Abstract: In this thesis, we investigate the security vulnerabilities present in sending a facsimile document over an IP network. We have developed and tested an intrusion mechanism, which is capable of intruding into the facsimile communication over the Public Switched Telephone Network (PSTN) section of the FOIP network without either communicating parties having any knowledge of intrusion taken place. Additionally, we describe the various techniques by which intrusion can take place over an IP network. Finally, we conclude by suggesting countermeasure to prevent the occurrence of such attacks on the FOIP network in the future. http://idea.library.drexel.edu/handle/1860/2927 Title: Factor structure of the miranda rights comprehension instruments—II <br/> <br/>Authors: Zelle, Heather <br/> <br/>Abstract: A waiver of Miranda rights is valid only if a suspect provides it knowingly, intelligently, and voluntarily. The Instruments for Assessing Understanding and Appreciation of Rights were created with the goal of assessing individuals‘ basic understanding of the Miranda rights (i.e., the knowing prong) and their appreciation of waiving those rights (i.e., the intelligent prong). The revised instruments, the Miranda Rights Comprehension Instruments-II, maintain that goal. It has been hypothesized that the component instruments load on two factors that comprise the knowing and intelligent requirements. The two-factor structure has been partially supported by product-moment correlations; however, a direct statistical analysis of the hypothetical structure has not been completed. The current study examined the factor structure of the MRCI-II. It was hypothesized that a two-factor model would provide the best fit, with the CMR-II, CMR-R-II and CMV-II loading on a factor constituting the understanding requirement and the FRI loading on a separate factor constituting the appreciation requirement. Data were collected from 183 adolescent boys and girls in pre- and post-adjudication facilities in Pennsylvania and Massachusetts. The MRCI-II, verbal sections of the WIAT and WASI, and Gudjonsson Suggestibility Scale -2 were administered to participants. Exploratory factor analysis revealed a two-factor model with the CMR-II and CMR-R-II loading on Factor 1, the FRI loading on Factor 2, and the CMV-II loading on Factors 1 and 2. Confirmatory factor analyses indicated the two-factor model provided a good fit to the data, as did a one-factor model, whereas a three-factor model provided a poor fit. http://idea.library.drexel.edu/handle/1860/2926 Title: Sleep in pediatric sickle cell disease <br/> <br/>Authors: Daniel, Lauren http://idea.library.drexel.edu/handle/1860/2925 Title: Depolarized light scattering and rheology of hydrogels <br/> <br/>Authors: Kolb, James Thomas <br/> <br/>Abstract: The goal of this thesis was to design, develop and characterize a non-destructive method to assess the mechanical properties of clear hydrogels using information from the depolarized scattering of focused light. There are currently no published commercially available systems with the ability to monitor remotely the crosslinking density of hydrogel systems. This new system will allow for accurate in-process monitoring and process optimization without the loss of product. The optical system developed uses inexpensive off-the-shelf components and measures the relative intensity, a qualitative measure that is correlated to the crosslinking density of ionically (Ca2+) crosslinked alginate gels. The incident laser (685 nm wavelength) is vertically polarized while the scattered light is collected after having been horizontally polarized The crosslinked sections of hydrogels, are structures where the local index of refraction varies when observed from different directions, that is they exhibit optical anisotropy. polarized light scattering is a sensitive measurement method for the investigation of systems exhibiting local anisotropy, such as macromolecules and liquid crystals. The polarized light is scattered from both isotropic and anisotropic structures within the media, and by measuring the depolarized light, the contribution of the anisotropic structures can be separated and assessed. We have used as a model hydrogel system sodium alginate hydrogels crosslinked by Calcium ions (in the form of CaCl2). The scattered depolarized light intensity is related to a “flow index”, a measure of apparent viscosity, and is directly related to the crosslinking density of the gel structure. The final designed system is sensitive to 1% changes in alginate concentration and .1% changes in calcium ion concentration.