Fish scales can be considered as a laminated composite based on collagen fibrils arranged in a cross-plywood structure. This collagen-based composite is often partially mineralized (primarily hydroxyapatite) in the scale exterior in order to resist penetration and hence to enhance protection. Together with the overlapping assembly, the fish scales offer an excellent model system for developing fiber composite materials and flexible armor systems. The primary objective of this thesis is to characterize the distribution of the mineral phase within individual scale and to investigate the corresponding mechanical consequences of the scale as a whole and its different fields through experimental and computational approaches. In this thesis, we chose the scales from the black drum (Pogonias cromis) fish as a model system. First of all, the exterior surface morphology of individual scales was systematically studied, from which several distinct structural regions are identified, including focus field (central), lateral field (dorsal and ventral), rostral field (anterior), and caudal field (posterior). In the focus field, the classic two-layer design, i.e., mineralized exterior layer and collagen-based interior layer, was observed, and nanoindentation results revealed that the high mineral exterior layer results in a much higher hardness (800 vs 450 MPa). Moreover, macroscopic tensile tests indicate that the mechanical removal of mineralized layer did not lead to reduction in strength values, whereas acid-treated demineralized scales showed reduced mechanical properties. Finally, we identified a previously unreported mineral distribution pattern in the rostral field, in which the mineral phase is segregated into long strips along the anterior-posterior direction (width, ~300 μm). In addition, towards the interior of the scale, it appears that the mineral deposition is highly correlated with the collagen orientation, resulting a unique mineralized-unmineralized collagen-based composite structure. We built finite element models to compare this unique structure to two other mineral phases in different fields at the individual scale. This unique structure demonstrates a larger deformation displacement when load was applied, indicating that it provides further flexibility in anterior end of an individual scale. The mineralized phases and structures of various fields within a single scale provide different mechanical characteristics and properties. The structural and mechanical analysis of the various regions of the fish scale can further investigate the flexibility and protective capacity of the individual scale. / Master of Science / There are many protective systems that attracted scientists' attention, and the typical examples include the nacre, crustacean exoskeletons, and teleost fish scales. Fish scales can be considered as the most common flexible bio-inspired armor system, because they consist of mostly collagen fiber and a highly mineralized hydroxyapatite external layer. Due to the need for swimming and effective protection from predators, fish scales need to have excellent flexibility and penetration resistance. In the previous studies on fish scales, researchers usually focused on the entire scale as a multilayered composite, looking at their response against tension and fracture. The primary objective of this thesis is to characterize the distribution of the mineral phase within individual scale and to investigate the corresponding mechanical consequences of the scale as a whole and its different fields through experimental and computational approaches. In this thesis, we chose the scales from the black drum (Pogonias cromis) fish as a model system. First of all, the exterior surface morphology of individual scales was systematically studied, from which several distinct structural regions were identified, including the focus field (central), lateral field (dorsal and ventral), rostral field (anterior), and caudal field (posterior). In the focus field, the classic two-layer design, i.e., mineralized exterior layer and collagen-based interior layer, was observed, and nanoindentation results revealed that the high mineral exterior layer results in a much higher hardness (800 vs 450 MPa). In addition, we identified a previously unreported unique mineralized-unmineralized collagen-based composite structure in the rostral field, in which the mineral phase is segregated into long strips along the anterior-posterior direction (width, ~300 μm). We built finite element models to compare this unique structure to two other mineral phases in different fields at the individual scale. This unique structure demonstrates a larger deformation displacement when load was applied, indicating that it provides further flexibility at the anterior end of an individual scale, implying that the flexibility is more important at the anterior end of scales where the multi-scales overlap and are covered. The structural and mechanical analysis of the various regions of the fish scale can further investigate the flexibility and protective capacity of the individual scale, and provide further design inspiration for flexible armor designs.

Over the past decade, relationship education has grown as a means of enhancing couple relations. This study examines the experiences of 2,828 ethnically diverse and low-income adults who participated in the Smart Steps for Stepfamilies: Embrace the Journey program, a 12-hour stepfamily education program. Self-report measures of relationship quality, couple commitment, and relationship instability were gathered prior to and immediately after the Smart Steps intervention as well as six weeks, six months, and one year post-program. Results suggest that stepfamily participants experienced increases in relationship quality; however, these increases reduced to near pre-program levels one year after the programs completion. Results further showed no changes in couple commitment or relationship instability measures nor among differing participant groups including Latinos, European Americans, low-income, moderate- income, married, unmarried, those in a first marriage, second remarriage, and higher order remarriage. Finally a cost-analysis of the program was conducted. Application of these findings and policy implications are discussed.

Search engines have forever changed the way people access and discover knowledge, allowing information about almost any subject to be quickly and easily retrieved within seconds. As increasingly more material becomes available electronically the influence of search engines on our lives will continue to grow. This presents the problem of how to find what information is contained in each search engine, what bias a search engine may have, and how to select the best search engine for a particular information need. This research introduces a new method, search engine content analysis, in order to solve the above problem. Search engine content analysis is a new development of traditional information retrieval field called collection selection, which deals with general information repositories. Current research in collection selection relies on full access to the collection or estimations of the size of the collections. Also collection descriptions are often represented as term occurrence statistics. An automatic ontology learning method is developed for the search engine content analysis, which trains an ontology with world knowledge of hundreds of different subjects in a multilevel taxonomy. This ontology is then mined to find important classification rules, and these rules are used to perform an extensive analysis of the content of the largest general purpose Internet search engines in use today. Instead of representing collections as a set of terms, which commonly occurs in collection selection, they are represented as a set of subjects, leading to a more robust representation of information and a decrease of synonymy. The ontology based method was compared with ReDDE (Relevant Document Distribution Estimation method for resource selection) using the standard R-value metric, with encouraging results. ReDDE is the current state of the art collection selection method which relies on collection size estimation. The method was also used to analyse the content of the most popular search engines in use today, including Google and Yahoo. In addition several specialist search engines such as Pubmed and the U.S. Department of Agriculture were analysed. In conclusion, this research shows that the ontology based method mitigates the need for collection size estimation.

This study aimed to investigate the acquisition of the four non-generic uses of the English definite article the by Arabic learners of English in Saudi Arabia. These non-generic uses included textual, situational, cultural and structural. This study had three goals: (1) to determine whether these uses are acquired in a certain sequence; (2) to explore which one of these uses is the most difficult and the easiest in learning; (3) to investigate whether one or two of the uses are overused. The instrument consisted of 59 sentences adopted from Liu and Gleason (2002). There were 40 instances for required uses and 20 sentences for obligatory nonuse (5 instances for each use). The subjects were instructed to insert the where they deemed it necessary. The participants were 45 male undergraduate English major students, whose ages ranged from 18 to 22 with a Mean age of 21.6, from a university in Saudi Arabia. They were divided into three groups (15 students each) based on their proficiency levels as follows; low intermediate, intermediate, and advanced. The results revealed developmental trends in the acquisition of the non-generic uses of the English definite article related to proficiency. Specifically, the advanced group showed significantly higher accuracy of use in all four functions. Regarding the four functions, the order of acquisition, based on level of accuracy was as follows: situational, cultural, structural and textual. The study results are discussed in view of their pedagogical implications for the teaching of the definite article to Saudi learners of English.

Current Automatic Palmprint Identification Systems (APIS) closely follow the matching philosophy of Automatic Fingerprint Identification Systems (AFIS), in that they exclusively use a small subset of Level II palmar detail, when matching a latent to an exemplar palm print. However, due the increased size and the significantly more complex structure of the palm, it has long been recognised that there is much detail that remains underutilised. Forensic examiners routinely use this additional information when manually matching latents. The thesis develops novel automatic feature extraction and matching methods which exploit the underutilised Level I detail contained in the friction ridge flow. When applied to a data base of exemplars, the approach creates a ranked list of matches. It is shown that the matching success rate varied with latent size. For latents of diameter 38mm, 91:1% were ranked first and 95:6% of the matches were contained within the ranked top 10. The thesis presents improved orientation field extraction methods which are optimised for friction ridge flow and novel enhancement techniques, based upon the novel use of local circular statistics on palmar orientation fields. In combination, these techniques are shown to provide a more accurate orientation estimate than previous work. The novel feature extraction stages exploit the level sets of higher order local circular statistics, which naturally segment the palm into homogeneous regions representing Level I detail. These homogeneous regions, characterised by their spatial and circular features, are used to form a novel compact tree-like hierarchical representation of the Level I detail. Matching between the latent and an exemplar is performed between their respective tree-like hierarchical structures. The methods developed within the thesis are complementary to current APIS techniques.

The organizational structure is unquestionably a very important managerial tool for firms. Based on the purpose of the structure, it has a large influence on how the operation of the firm is performed, which can create incentives for picking the most suitable one. According to the contingency theory, there is no best option, the most suitable structure is dependent on contextual factors in each individual case. Contrary, previous studies have shown that organizational structure has significant influence on the performance and even certain types of structures.There is currently a research gap regarding if certain types of structures could lead to better financial performances. This quantitative study was conducted using a positivistic paradigm, with a deductive approach. 216 companies were analyzed and two-sample t- tests were conducted to test the data. The divisional, functional, hierarchical, horizontal, and matrix organizational structures have been used and the financial performance measures Return on Assets, Return on Equity, and Return on Invested Capital. Industry and country have been used as descriptive variables.By conducting a MANOVA test the first research question was answered, “Does the organizational structure influence the firm’s financial performance?”, the results were insignificant, the organizational structure does not influence the firm’s financial performance. This question provided an aggregated view of the influence of structures while the second question was aimed to provide a decomposed view by looking closer at the influence of the structures against each other.To answer the second research question, “Is there a certain organizational structure that has a higher influence on the firm’s financial performance?”, several two-sample t-tests were conducted. The results from the two-sample t-tests show that there is a significant difference in the Return on Assets when using a divisional structure rather than a matrix structure and that there is a significant difference on the Return on Equity when using a functional structure rather than a divisional structure and when using a hierarchical structure rather than a divisional structure. To summarize, the result of this study aligns with the contingency theory, the best structure is very much a personal choice for each organization and should not be chosen by financial interests.

No description available.

Stem cell transplant is often considered the last hope for the survival for many cancer patients. The CD34+ cell content of a collection of stem cells has appeared as the most reliable indicator of the quantity of desired cells in a peripheral blood stem cell harvest and is used as a surrogate measure of the sample quality. Factors predicting the yield of CD34+ cells in a collection are not yet fully understood. Throughout the literature, there has been conflicting evidence with regards to age, gender, disease status, and prior radiation. In addition to the factors that have already been explored, we are interested in finding a cancer-chemotherapy interaction and to develop a predictive model to better identify which patients will be good candidates for this procedure. Because the amount of CD34+ cells is highly skewed, most traditional statistical methods are inappropriate without some transformation. A Bayesian generalized regression model was used to explain the variation of CD34+ collected from the sample by the cancer chemotherapy interaction. Missing data was modeled as unknown parameters to include the entire data set in the analysis. Posterior estimates are obtained using Markov chain methods. Posterior distributions identified weight and gender as well as some cancer-chemotherapy interactions as significant factors. Predictive posterior distributions can be used to identify which patients are good candidates for this procedure.

Understanding how habitat amount and configuration affect species richness, occurrence or abundance has been one of the major foci of research in ecology and biogeography, given its central importance for conservation planning and landscape management. We conducted bird point counts within clearcuts and mature pine stands of different sizes and configuration in working pine forest in north-central Mississippi to determine species associations. Early-successional and mature pine focal species showed varying response to the proportion and proximity of vegetation conditions in the landscape. While elements of configuration exhibited a greater influence on predicted avian abundance in this landscape, meaning many species require a mosaic of habitat conditions that come from both early-successional and mature vegetation types. Efforts to combine management of timber and conservation of songbirds must consider both species’ habitat requirements and the distribution of these requirements in the landscape.

No description available.