bluuebunny/crossref_metadata_2025 huggingface dataset:
Caregiver social problem solving and depression in heart failure patients
Authors:   , Salber Kristin Elizabeth , Nezu Arthur M.
Published: July 2021

Deficits in Social Problem Solving (SPS) have been linked to depression in many populations, including college students, cardiac patients, and caregivers of individuals with Alzheimer's disease. Although research has typically focused on SPS and depressive symptoms within the individual, there is evidence to suggest that deficits in SPS among family caregivers are associated with poorer physical and psychological outcomes in the patients for whom they care. However, to date, no study has examined this relationship while controlling for patients' own SPS abilities. This study examined the relationship between patient and caregiver SPS and depressive symptoms in families coping with Heart Failure (HF), a condition in which depression is not only common, but is also associated with an increased risk of functional decline and death. It was hypothesized that deficits in caregiver SPS would be significantly associated with depressive symptoms in HF patients, even after controlling for patients' own SPS abilities. Thirty-two HF patients and their family caregivers completed self-report measures of SPS, functional independence, and depressive symptoms. Results of a Pearson correlation failed to support the hypothesis that caregiver SPS is associated with patient depressive symptoms. However, robust correlations were observed among patient and caregiver SPS abilities. Specifically, caregiver negative problem orientation (NPO) and impulsive/carelessness problemsolving style (ICS) were significantly associated with patient NPO and overall problem-solving deficits. Relationships among other SPS deficits approached statistical significance. These results suggest that additional research is warranted to explore the role of SPS within an emotional system.
Electrospun crosslinked hyaluronic acid fibers for tissue engineering applications
Authors:   , Toth Laura J. , Schauer Caroline L.
Published: July 2021

In the United States, organ transplant demand overwhelms the available supply. Numerous diseases and afflictions, such as burn trauma, are conditions which require accelerated tissue growth and repair in order for those affected to recover or even to survive. Regenerative medicine is a discipline which seeks to repair and restore existing damaged organs and tissues utilizing knowledge from a variety of scientific genres, including material science and engineering. Electrospinning is a cost effective and simple technique that is used to produce non woven fibrous meshes out of polymers. These three dimensional (3D) fibrous meshes can mimic the architecture of the natural extracellular matrix (ECM) of the cell, which is critical for cell adhesion, proliferation, and growth. Here, we investigate the fabrication of an enhanced mesh or scaffold for tissue engineering applications by electrospinning the connective tissue extracellular matrix component hyaluronic acid (HA) in a novel neutral solvent system. Moreover, we address the current issue of maintaining the fibrous structure of electrospun biopolymer mats by crosslinking our HA fibers with divinyl sulfone (DVS). The crosslinked HA mats were chemically stable and did not degrade in aqueous solutions. The morphology, chemical interactions and stability of the formed HA fiber mats were characterized using SEM, FTIR, and solubility tests, respectively. Cell viability studies indicate that HA mats allowed the normal, healthy growth of viable HeLa cells when viewed under a fluorescent confocal microscope. Interestingly, microspike projections within the fluorescently tagged cytoskeleton of the cells indicate an enhanced interaction of the cell ECM and electrospun 3D fibrous scaffolds. These new methods of electrospinning will develop a dressing that should enhance or promote therapeutic wound healing.
Poly(ethylene oxide)/cellulose-nanocrystal nanocomposites as polymer electrolyte membranes
Authors:   , Wald Nathan , Li Christopher Y.
Published: July 2021

Over the past several decades battery technology has fallen behind the tremendous growth seen in other technological industries, such as microprocessors and computer memory. For today's wireless technology to continue to improve, the need for batteries capable of storing a greater amount of charge in a small package is of paramount importance. One of the most promising routes to achieve this goal is to use lithium ions as the charge carrier. This is because lithium is lightweight and has a very high redox potential. However, the lifespan and safety of lithium based batteries have been problems since their inception, resulting in scientists constantly working to improve the mechanical properties of the electrolyte without greatly reducing its ionic conductivity. In the following thesis a system of poly(ethylene oxide) (PEO) with lithium perchlorate (LiClO4) salt and cellulose nanocrystals (CNCs) is investigated to determine its usefulness as a solid polymer electrolyte. It is seen that the addition of CNCs increase the crystallinity of the PEO-LiClO4 system, resulting in an enhancement of the mechanical properties. While increased crystallinity is also usually associated with a decrease in ionic conductivity this was not observed. Instead it is proposed that the CNCs act as a Lewis Acid, competing with lithium cations for ether oxygen atoms along the PEO chain. This competition results in a decrease in the strength of binding between the PEO and lithium ions, causing the lithium to diffuse much more easily and thus have higher conductivity when compared to a sample with no CNCs. It was also seen that the ionic conductivity of these solid polymer electrolytes improves with increasing temperature. To further improve the conductivity, dimethylformamide (DMF) was then used as a liquid plasticizer. The plasticizer allows the polymer chains to reptate more easily, improving the ionic conductivity of the sample. A three order of magnitude improvement in conductivity over the completely dry films was observed with the addition of up to 30% DMF. Unfortunately, with this improvement in conductivity comes a slight reduction in the modulus of the films. However this work does lay the foundation of using a nanofiller to improve the mechanical properties of an electrolyte at the expense of the conductivity and then add a plasticizer to somewhat reduce the mechanical properties while greatly improving the conductivity. When carefully balanced, these two additions can result in an electrolyte with moderately improved mechanical and conductivity properties.
Development of a Nutrition Education Curriculum for Teachers that includes Lessons and Activities for Children Grades Pre-kindergarten through Seven
Authors:   , Wilson Amber , Klassen Ann Carroll
Published: July 2021

Background: Rates of childhood obesity have increased dramatically from only one generation ago. Co-morbidities associated with obesity have also risen in children. One of the factors that lead to obesity is poor nutrition. After-school and daycare programs have been cited as places were nutrition education can be conducted to teach children the importance of a healthful diet. Objectives: Diversified Community Services (DCS) wanted to create a nutrition curriculum that could be used by its childcare staff to teach children the importance of eating healthfully. Therefore, the purpose of this thesis was to create an age appropriate curriculum. The second objective was to create a survey to measure community members' perceptions of the availability of fruits and vegetables at a local corner store. Methods: A literature review was used to identify evidence based information on curriculum development. Cognitive testing was conducted to test evaluation materials for the curriculum. A literature review was also conducted to design the community needs assessment survey. Results: Based on formative and evidence based information, a nutrition curriculum was developed. Pre-/post-tests were created to measure the effectiveness of the curriculum. A community needs assessment survey was developed to be used by DCS in the near future to measure fresh produce availability. Conclusion: The development of the curriculum will be a sustainable way for DCS to provide nutrition education to children under their supervision. The community needs assessment survey can be utilized to gauge the availability of fresh fruits and vegetables in the neighborhood corner store.
Blood Total Mercury Levels and Depression in the United States
Authors:   , Ng Tsz Hin (Stanley) , Mossey Jana M.
Published: July 2021

BackgroundMercury is a neurotoxin that is associated with depression. The US population is exposed to low-levels of mercury from dental amalgam or fish consumption. It is unclear whether an association between mercury and depression is present in the US household population. MethodsA total of 6,911 adults (age [greater than or equal to]20) from the National Health and Nutrition Examination Survey (NHANES), 2005-2008 were included in this study. Blood total mercury of participants was assessed. Patient Health Questionnaire-9 was used to screen for depression (presence of any depressive spectrum disorders; score 5-27). The sample was analyzed as a whole or by age strata (younger adults: age 20-39; older adults: age [greater than or equal to]40). Chi-square tests and logistic regression were used to examine the relationship between blood total mercury and depression. ResultsWhole sample analysis suggested that blood total mercury quintiles were inversely associated with depression (p<0.05; OR = 0.49, 95% CI: 0.36-0.65, comparing the highest to the lowest blood total mercury quintiles). This association largely disappeared after adjustment for SES. Among younger adults, no significant association between blood total mercury and depression was observed. Among older adults, the inverse relationship between blood total mercury and depression was confounded by SES but remained statistically significant. Further adjustment for other covariates did not affect the results. ConclusionsA lower risk of depression was observed among individuals having a higher level of blood total mercury, but this association was confounded by SES. The persistent inverse relationship among the older population may be due to residual confounding.
Emergency Contraception
Authors:   , Linares Karina , Evans Alison A.
Published: July 2021

Background: Emergency contraceptive pills, or ECP, are proven to be a safe and effective method of preventing unintended pregnancy. However, use of the method is low. With 3 million unintended pregnancies in the U.S. each year, factors affecting ECP use, including awareness and knowledge, should be explored to increase usage. Objectives: 1) To assess the levels of awareness, knowledge, and use of ECP among the study population; and 2) to determine the significant demographic characteristics that play a role in ECP awareness, use, and knowledge. Methods: An anonymous 20-question survey was completed by (n=157) adult female visitors of two Philadelphia Planned Parenthood health centers. The survey was designed to collect basic demographic information and to measure knowledge, attitudes, and beliefs towards ECP. Chi-square analyses, Fisher's exact tests, and logistic regression were used to examine factors that may predict ECP awareness, use, and knowledge. Results: The majority of women (83.44%) expressed awareness of ECP. Women with some college education or greater were more likely to be aware of ECP than those with lower education levels. Women younger than 35 were more likely to have used ECP than those older than 35, as well as women who have had previous pregnancies. Contraceptive use was also associated with previous ECP use. For ECP knowledge, prior ECP use was a significant predictor. Conclusion: Although awareness of ECP is high, use and knowledge still vary in several population groups. More effort is needed to raise overall knowledge of ECP to those groups at risk of unintended pregnancy.
The Effects of Chronic Wasting Disease on the Pennsylvania Cervid Industry Following Its Discovery
Authors:   , Romano Maria , Mossey Jana M.
Published: July 2021

Background: Chronic Wasting Disease (CWD) is a Transmissible Spongiform Encephalopathy (TSE) affecting deer and Rocky Mountain elk. The disease affects the central nervous system resulting in brain lesions, and once infected, the disease has a 100% case fatality rate. CWD is a major concern for the state of Pennsylvania. The Commonwealth has the second largest domestic cervid industry in the country and is third in the country for the number of captive deer or elk. Objective: To predict, using captive cervid data, the probable spread and effects of a CWD epidemicwithin the deer industryDesign: Computer simulated epidemic outbreaks of CWD using a deer movement network analysis and traditional gravity model were developedSetting:The Pennsylvania captive cervid industry, 1997-2011Data Sources: United States Animal Health Emergency Reporting Diagnostic System DatabaseResults: 10,000 CWD simulations were 1108 farms, 65% of epidemics were relatively mild, (<14 farms); 48% included index farm only; 14% included one farm in addition to the index farm. Of the severe epidemics, the mean was 620.5±13.44 farms infected, (range 571 - 666). Mean length of the severe epidemics was 159 months (range 121-259 months). Conclusion: Despite the inherent limitations of the model, this study is the first of its kind to develop a potential spread of CWD using actual captive deer data before the introduction of the disease into a state. As a result, the findings of the study can be used as an instructional tool on the effects of CWD in the event of an outbreak.
Improving the Epidemiology of Alcohol-Related Violence in the City of Philadelphia Using Geospatial Analysis
Authors:   , Nobis Elizabeth , Mossey Jana M.
Published: July 2021

Background: In the United States, alcohol related violence is a major public health problem. There is a significant amount of evidence suggesting that the density of alcohol outlets and the level of social disorganization in a neighborhood are related to levels of violent assault. Less is known about the spatial distribution of assaults surrounding these alcohol outlets including the neighborhood characteristic of vacant lots. Better understanding these spatial linkages will contribute to improvements in the public health efforts to suppress violence and morbidity. Objective: This project aims to determine whether the density of alcohol outlets in Philadelphia is associated with neighborhood levels of violence and whether this relationship is influenced by the density of vacant lots. It was then investigated how violence geographical clusters around these spaces. Methods: This study utilized police-recorded data of aggravated assaults in Philadelphia, alcohol outlet addresses in Philadelphia, and 2010 Census Bureau block group information. Descriptive statistics, regression, spatial clustering, and qualitative mapping analysis were used to identify the distribution and relationships of assaults in the city. Results: Areas with higher percentages of vacant housing in combination with high density of alcohol outlets have a positive relationship with increased levels of aggravated assaults. This effect is most evident in economically disadvantaged areas. Conclusion: There is significant evidence that aggravated assaults are spatially linked to alcohol outlets and vacant lots. Development of alcohol policy, as well as improving neighborhood environments in low-income areas will reduce alcohol-related violence and improve the safety of Philadelphia's general public.
Characters Welcome
Authors:   , Toner Allison Lynn , Tedesco Albert S.
Published: July 2021

The television industry has clearly evolved from a time when the "Big Three" broadcast networks, NBC, ABC, and CBS dominated the tube. The "Big Three" were the only viewing options and each had their own unique style of programming. However, those golden days of television are in the past and today viewers have hundreds of channel options and different ways to watch, both broadcast and cable networks. Thus, the need for a network to differentiate itself from others has grown tremendously. One important way to achieve this is by creating a brand. For television networks, the primary purpose of a brand is define its identity and to help it stand out against competition. However, broadcast and cable networks take different approaches to branding. Cable brands are much more obvious. USA Network is a key example of a cable channel that has used branding successfully. In 2005, USA Network launched its Characters Welcome brand. In USA's case, the brand is used in every aspect of the network, especially in the original programming. There is a unique symbiotic relationship between the Characters Welcome brand and the programming. Meaning that the three elements of the brand, (1) "Blue Sky," (2) A slightly flawed but likeable central character who is best at his or her career, and (3) levity or touch of humor are incorporated into the original programming. Since this new brand was established, USA changed from a fledgling network into one that has received many industry accolades including becoming the number one cable network for six years running. Accordingly, this case study focuses on the growth of USA Network, its brand and original programming. It also tests the specific relationship between the Characters Welcome brand and the programming through observation of selected episodes of the two oldest series Psych and Burn Notice plus the two freshman series Necessary Roughness and Suits. Throughout the observation, the three elements of the Characters Welcome were searched for in the episodes. The findings of this case study shed some light on the relationship between USA's brand and programming. Plus, if the network's newest shows are consistent with the brand. Furthermore, the case study will provide USA Network's plan for future programming and how it can attempt to keep the brand fresh.
Generative topic modeling in image data mining and bioinformatics studies
Authors:   , Chen Xin , Hu Xiaohua
Published: July 2021

Probabilistic topic models have been developed for applications in various domains such as text mining, information retrieval and computer vision and bioinformatics domain. In this thesis, we focus on developing novel probabilistic topic models for image mining and bioinformatics studies. Specifically, a probabilistic topic-connection (PTC) model is proposed for co-existing image features and annotations, in which new latent variables are introduced to allow for more flexible sampling of word topics and visual topics. A perspective hierarchical Dirichlet process (pHDP) model is proposed to deal with user-tagged image modeling, associating image features with image tags and incorporating the user's perspectives into the image tag generation process. It's also shown that in mining large scale text corpora of natural language descriptions, the relation between semantic visual attributes and object categories can be encoded as Must-Links and Cannot-Links, which can be represented by Dirichlet-Forest prior. Novel generative topic models are also introduced to meta-genomics studies. The experimental results show that the generative topic model can be used to model the taxon abundance information obtained by the homology-based approach and study the microbial core. It also shows that latent topic modeling can be used to characterize core and distributed genes within a species and to correlate similarities between genes and their functions. A further study on the functional elements derived from the non-redundant CDs catalogue shows that the configuration of functional groups encoded in the gene-expression data of meta-genome samples can be inferred by applying probabilistic topic modeling to functional elements. Furthermore, an extended HDP model is introduced to infer functional basis from detected enterotypes. The latent topics estimated from human gut microbial samples are evidenced by the recent discoveries in fecal microbiota study, which demonstrate the effectiveness of the proposed models.
Direct and indirect effects of recreational boats on diamondback terrapins (Malaclemys terrapin)
Authors:   , Lester Lori A. , Avery Harold W.
Published: July 2021

Recreational boating has become an increasingly popular activity over the past 100 years as a result of extensive human population growth in coastal areas. Recreational boats may affect aquatic organisms directly through injury and mortality due to boat strikes and indirectly though increased levels of anthropogenic sounds. The objective of this study was to determine whether recreational boats affect diamondback terrapin (Malaclemys terrapin) populations in Barnegat Bay, New Jersey, USA. I used six years of mark-recapture data to determine whether terrapin injury rates have increased temporally and whether larger terrapins had a higher risk of anthropogenic injury than smaller terrapins. I also used a Cormack-Jolly-Seber (CJS) model to determine if survivorship differed between injured terrapins and uninjured terrapins. In some locations, injury rate of terrapins increased from 2006 to 2011. Larger terrapins were found to be more likely than smaller terrapins to be injured by boats or automobiles. Injured terrapins in some locations also had significantly lower survivorship than uninjured terrapins. I recorded Auditory Evoked Potentials (AEPs) to determine hearing capability of diamondback terrapins in air and underwater. Terrapins responded to sounds from 100 to 1000 Hz with best hearing from 400 to 600 Hz in air. Underwater, terrapins responded to sounds from 50 to 800 Hz with mean lowest threshold of 86 dB re 1 [mu]Pa rms. I recorded sounds of recreational boats and personal watercraft (PWC) in Barnegat Bay and found that boats and PWCs produce sounds that are in the hearing range of diamondback terrapins. Diamondback terrapins were exposed to playback recordings of approaching boat engines in situ. I measured behavioral responses to boat engine sounds including swimming speed, swimming depth, and orientation of terrapin in the water column. Diamondback terrapins did not behaviorally respond to sounds of approaching boats. The lack of behavioral response of diamondback terrapins to recreational boats threatens the survival of terrapin populations. Conservation actions (such as boater education, speed limits, and partial or complete closures of wildlife areas to boats) must be initiated to protect aquatic wildlife from injury and mortality from recreational boats.
The impact of authentic leadership and adverse selection conditions on escalation of commitment
Authors:   , Roberts Ross P. , Tsakumis George T. , Cianci Anna , Agoglia Christopher P. , Grein Barbara M. , Werner Edward , Zeigert Jonathan
Published: July 2021

The objective of this study is to examine the impact of authentic leadership on escalation of commitment under the presence or absence of adverse selection conditions (i.e., the presence of motive and opportunity). Prior research documents that when adverse selection conditions exist managers are more likely to behave in their own interest and continue failing projects. Whereas prior research has mostly focused on economic factors as methods to moderate the effects of adverse selection conditions, this study will examine the role of leadership style in curtailing escalation behavior. Authentic leadership is a leadership style that allows the leader to transparently display an internalized moral perspective, balanced processing, and self-awareness. Utilizingsocial identity theory, I hypothesize that authentic leadership will reduce escalation of commitment by increasing the managers' propensity to emulate the moral behavior of an authentic leader. In order to examine the effect of authentic leadership I conduct a study in which authentic leadership and adverse selection conditions are manipulated to discover their impact on escalation of commitment. The utilizes a 3x2 design where authentic leadership is manipulated as low, neutral, or high and adverse selection conditions are manipulated as present or not present. Consistent with the predictions I find that authentic leadership mitigates the effect of adverse selection conditions on escalation of behavior. Specifically, when adverse selection conditions are present, project managers supervised by an authentic leader are less likely to continue a failing project. By identifying a personal interaction variable (authentic leadership) that may mitigate the effects of adverse selection conditions, I can provide organizations with additional methods to reduce unethical decision making, specifically the continuing of failing projects.
Anion exchange membranes derived from nafion precursor for the alkaline fuel cell
Authors:   , Salerno Holly Lynn Schaeffer , Elabd Yossef A.
Published: July 2021

Alkaline fuel cells (AFCs) have the potential replace proton exchange membrane fuel cells in portable power applications due to its lower cost. However, this will require robust chemically stable alkaline anion exchange membranes (AEMs) to ensure long performance lifetimes in solid-state AFCs. In this study, we utilized solid-state chemistry to synthesize Nafion-based AEMs with a variety of covalently attached cations, including trimethylammonium, trimethylphosphonium piperazinium, pyrrolidinium, pyridinium and quaternized 1,4'-diazabicyclo[2.2.2]octane (DABCO). Infrared spectroscopy confirms the partial asymmetric functionalization of all AEMs synthesized except pyridinium. The conductivity of all AEMs were similar and approximately 5 fold lower than proton conducting Nafion at 80 °C and 90% relative humidity. The effect of cation type on AEM chemical and thermal stability was investigated as a function of various conditions (e.g., hydration levels, temperature, and pH). High chemical and thermal stability was observed for all successfully synthesized AEMs with the exception of the trimethylphosphonium cation AEM. A kinetic study on the reaction between dimethylpiperazine and the Nafion precursor revealed that the optimum conditions were at room temperature for 72 h. These results show that Nafion precursor derived AEMs provide promising membranes for future low-cost long-lasting AFCs.
Assessing Feasibility of a Learning Collaborative Using Sanctuary Model as a Framework
Authors:   , Bergey Maureen G. , Bloom Sandra L.
Published: July 2021

The prevalence of trauma and its associated impacts on individuals, families, organizations, and communities are increasingly recognized by the public, policy makers, and funders. Traumatic experiences also influence the risk of chronic disease and poor health outcomes throughout the lifespan, placing strain on the healthcare system. These economic, physical, and psychological burdens are increasing the stress on human service organizations. In light of the chronic stress faced by human service organizations providers are operating in silos, which impedes progress in developing trauma-informed networks of care. Trauma-informed care acknowledges trauma symptoms and experiences, while incorporating understanding of the impacts of trauma at all levels of an organization, from services to policies. The Sanctuary Model® is one trauma-informed model, which uses a whole systems approach designed to reduce stress within human service organizations. This project investigates the feasibility of using the Sanctuary Model® as the framework for a learning collaborative to implement a trauma-informed network of care in an urban area among several parts of the human service system. Learning collaboratives bring together professionals across settings to advance and disseminate best practices, while fostering continuity of care. Sixteen semi-structured interviews were conducted with key-informants in human service organizations, and analyzed for common themes. The primary themes emerging from the data included: collaboration, indications for trauma-informed care, necessities of collaboration for trauma-informed networks, envisioning the future, and foundations for implementing learning collaboratives using the Sanctuary Model®. These themes will inform cross-systems decision making and framing of future collaborations.
Investigation of electrode materials for an electrochemical flow capacitor
Authors:   , Campos Jonathan William , Gogotsi Yury , Kumbur Emin Caglan
Published: July 2021

A recently introduced electrical energy storage concept, the electrochemical flow capacitor (EFC), holds much promise for grid-scale energy storage applications. The EFC utilizes the principles behind the operation of flow batteries and supercapacitors, and enables rapid charging/discharging and decoupled energy/power ratings. Electrical charge is stored in a flowable carbon slurry composed of low-cost and abundant carbon in neutral, aqueous electrolyte. Charge storage and transfer is analogous to solid carbon electrodes in conventional supercapacitors. Here, the effects of carbon particle solid fraction, shape and size on the electrochemical and flow properties of slurry electrodes are investigated. A static cell configuration is utilized for studying the electrochemical properties of the flowable electrodes. The electrochemical properties of the slurry electrodes tested in a static cell are found to be similar to that of solid electrodes in conventional supercapacitors for large spherical and commonly used anisometric activated carbons. Flow properties of the slurry electrodes are obtained for shear rates corresponding to pumping shear rates by rheometry. The results indicate that electrochemical and rheological properties of slurries depend on their concentration and also shape and size of the carbon particles used in the slurries. For a range of concentrations, slurries based on spherical carbon particles show lower viscosities compared to anisometric activated carbon based slurries while performing similar electrochemically.
An investigation into variability conditions in the SRE 2004 and 2008 Corpora
Authors:   , Cinciruk David A. , Walsh John MacLaren
Published: July 2021

In Automatic Speaker Verification, a computer must detemine if a certain speech segment was spoken by a target speaker from whom speech had been previously provided. Speech segments are taken over many conditions such as different telephones, microphones, languages, and dialects. Differences in these conditions result in a variability that can both negatively and positively affect the performance of speaker recognition systems. While the error rates are sometimes unpredictable, the large differences between the error rates of different conditions provokes interest in ways to normalize speech segments to compensate for this variability. With a compensation technique, the error rates should decrease and become more consistent between the different conditions used to record them. The majority of research in the speaker recognition community focuses on techniques to reduce the effects of variability without analyzing what factors actually affect performance the most. To show the need for a form of variabiality compensation in speaker recognition as well as to determine the types of variability factors that most significantly influence performance, a speaker recognition system without any compensation techniques was formed and tested on the core conditions of NIST's Speaker Recognition Evaluations (SREs) 2004 and 2008. These two datasets are from a series of datasets that organizations in the speaker recognition community use most often to show performance for their speaker verification system. The false alarm and missed detection rates for individual training and target conditions were analyzed at the equal error point over each dataset. The experiments show that language plays a significant role in affecting the performance; however, dialect does not appear to have any influence at all. Consistently, English was proven to provide the best results for speaker recognition with baseline systems of the form utilized in this thesis. While there does not seem to be a single best phone and microphone for speaker recognition systems, consistent performance could be seen when the type of phone and microphone used is the same for both training and testing (matched) and when they are different (mismatched). Higher missed detection rates could be seen in mismatched conditions and higher false alarm rates could be seen in matched conditions. Interview speech was also found to have a much higher difference between false alarm and missed detection than phone speech. The thesis culminates with an in-depth of the error performance as a function of these and other various variability factors.
316L stainless steel scaffolds by freeze casting for biomedical applications
Authors:   , Le Thao Vi , Wegst Ulrike G. K.
Published: July 2021

One major shortcoming found in current bone implant materials is that their mechanical properties exceed those of natural mineralized bone tissue by orders of magnitude. This mismatch in mechanical properties is the source of the reduction in bone density that occurs surrounding implants. This occurrence, known as stress shielding, is inevitable with today's bone substitute materials. Freeze casting allows for a simple one step technique to create a scaffold that can be tailored to match the porosity and mechanical properties of bone. Highly porous materials with cellular structures are known to have attractive combinations of physical and mechanical properties, such as high stiffness and strength per unit weight. Freeze casting, also known as "ice-templating" or directional solidification, is a processing technique used to create extremely porous structures with highly aligned interconnected pores. At the present time, freeze casting has been frequently applied to polymers and ceramics. However, to date, only four studies on metals have been published, all on the freezing casting of titanium. In this study, 316L stainless steel scaffolds were produced by freeze casting. With 70% porosity, these scaffolds achieved yield strengths of 32 MPa and Young's moduli of 940 MPa, values that fall into the strength and stiffness range of cancellous bone.
Analysis of a strange attractor in R⁴
Authors:   , Coy Benjamin , Gilmore Robert
Published: July 2021

Strange attractors in R³ are remarkably well understood because they may be classified through a topological analysis. This involves determining the organization of the unstable periodic orbits in the attractor by computing linking numbers for pairs of these orbits and then identifying a branched manifold that supports these and all other orbits, and serves to identify the mechanism that generates chaotic behavior. This topological invariant can be calculated in R³ but there is no analog for higher dimensions. We analyze a strange attractor generated by a four dimensional dynamical system and show the first steps in extending the current topological analysis program to higher dimensions. The linking numbers for pairs of unstable periodic orbits are computed in three different ways. Firstly, through projections of the attractor to three dimensional subspaces. Secondly, using a recently proposed higher dimensional linking integral to compute linking numbers in R⁴ for the first time. Thirdly, with a dimensionality reduction technique, Locally Linear Embedding, that successfully represents pairs of orbits in three dimensions allowing the organization within the strange attractor to be determined.
Exploration of the quantitative aspects of the MALDI TOFMS analysis of peptides
Authors:   , Mahan Andrew David , Owens Kevin Glenn
Published: July 2021

The focus of this thesis was on the analysis of peptides, paying particular attention to the physicochemical properties of the peptide which have the largest impact on the measured MALDI TOFMS signal. In the first project, typical MALDI samples containing matrix and analyte are investigated using electrospray ionization (ESI)-MS. The goal was to ascertain the role that the nonvolatile acidic matrix compound such as [alpha]-cyano-4-hydroxycinammic acid (CHCA) has on the observed charge states of peptides at increasing matrix-toanalyte ratios. In the second project, several methods of MALDI sample preparation are studied by MALDI Imaging to evaluate analyte homogeneity and signal reproducibility within a sample, as well as overall spectral quality. The third project involves a series of experiments designed to gain a better understanding of the effect of peptide structure on the MALDI TOFMS signal response. It is generally understood that increases in the hydrophobicity of the peptide leads to a decrease in the MALDI signal, while an increase in the number of basic groups present (lysine, arginine, histidine and the amine terminus) leads to large increases in the observed MALDI signal. This work goes a step further by investigating how the proximity of and exact location of multiple basic sites in the peptide chain affects the MALDI signal. The initial hypothesis was that increased separation of the basic sites would lead to the observation of higher signal by increasing the sphere of capture for protons in the desorbing MALDI plume. Rudimentary molecular modeling is used to rationalize the results obtained. The final project investigates the effect of the acid/base properties of both the peptide and matrix on the number of positive versus negative ions observed in the MALDI spectrum. This work explores the two-step model of ionization in MALDI described by Knockenmuss (Int. J. Mass Spectrom., 2008, 273, 84-86). In both cases electrospray deposition (rather than the conventional dried droplet method) is used to produce highly homogeneous MALDI samples that yield highly reproducible analyte ion signal. These results are important to those seeking to understand the observed sequence coverage obtained in peptide mass mapping or ladder sequencing type experiments.
Rapid impact modal testing for bridge flexibility
Authors:   , Prader John Blair , Aktan Ahmet Emin
Published: July 2021

Current infrastructure condition evaluation by visual inspection is a subjective endeavor while maintenance, repair and retrofit are effective only when designed and implemented by engineers with extensive experience and heuristic knowledge. As experienced engineers retire and as available funds dwindle, infrastructure owners, managers, and operators face a loss of expertise as well as diminishing resources for preservation and renewal. In this research, an integrated analytical/experimental strategy and an associated experimental tool is proposed for an objective evaluation of bridge condition to supplement visual inspection. Termed as rapid modal analysis, this test technique aims at reducing both the time and personnel required to produce estimates of bridge flexibility at strategic coordinates using spatially truncated measurement grids. The reported research started with an overview of modal analysis by impact and through the process of applying modal analysis to bridges, limitations to its widespread application were identified including, time and personnel requirements, traffic control requirements, and scaling factor reliability. To address these limitations several mitigation strategies were identified, validated, and implemented to increase the applicability of modal analysis for evaluating large populations of bridges. The use of a spatially truncated measurement grid to evaluate bridge flexibility along a girder, diaphragm, or traffic lane was evaluated by examining the variability of flexibility estimates at a point using a full grid, truncated grid, and single point estimates of flexibility. It was found that reliable estimates of flexibility were possible using truncated measurement grids by integrating individual single input multiple output test setups. To overcome the identified problems in obtaining reliable scaling factors, the use of an analytical mass matrix for scaling of mode shapes was examined using several simulated impact tests subjected to extraneous noise sources. It was determined that the use of an analytical mass matrix for mode shape scaling is a reliable substitute for traditional scaling methods if accurate estimates of material properties are available.
Carbon nanotube based devices for intracellular analysis
Authors:   , Singhal Riju Mohan , Gogotsi Yury
Published: July 2021

Scientific investigations on individual cells have gained increasing attention in recent years as efforts are being made to understand cellular functioning in complex processes, such as cell division during embryonic development, and owing to realization of heterogeneity amongst a population of a single cell type (for instance, certain individual cancer cells being immune to chemotherapy). Therefore devices enabling electrochemical detection, spectroscopy, optical observations, and separation techniques, along with cell piercing and fluid transfer capabilities at the intra-cellular level, are required. Glass pipettes have conventionally been used for single cell interrogation, however their poor mechanical properties and an intrusive conical geometry have led to limited precision and frequent cell damage or death, justifying research efforts to develop novel, non-intrusive cell probes. Carbon nanotubes (CNTs) are known for their superior physical properties and tunable chemical structure. They possess a high aspect ratio and offer minimally invasive thin carbon walls and tubular geometry. Moreover, possibility of chemical functionalization of CNTs enables multi-functional probes. In this dissertation, novel nanofluidic instruments that have nanostructured carbon tips will be presented along with techniques that utilize the exceptional physical properties of carbon nanotubes, to take miniature biomedical instrumentation to the next level. New methods for fabricating the probes were rigorously developed and their operation was extensively studied. The devices were mechanically robust and were used to inject liquids to a single cell, detect electrochemical signals and enable surface enhanced Raman spectroscopy (SERS) while inducing minimal harm to the cell. Particular attention was focused on the CVD process-which was used to deposit carbon, fluid flow through the nanotubes, and separation of chemical species (atto-liter chromatography) at the nanometer scale that would potentially lead to the highly sought after "selective component extraction" and analysis from a single cell. These multi-functional devices therefore provide a picture of the physiological state of a living cell and function as endoscopes for single cell analysis.
Incremental knowledge discovery in social media
Authors:   , Tang Xuning , Yang Christopher C.
Published: July 2021

In light of the prosperity of online social media, Web users are shifting from data consumers to data producers. To catch the pulse of this rapidly changing world, it is critical to transform online social media data to information and to knowledge. This dissertation centers on the issue of modeling the dynamics of user communities, trending stories, topics and user interests in online social media. However, knowledge discovery and management in online social media is challenging because: 1) social media data arrive in the form of continuous streams; 2) the volume of social media data is potentially infinite; and 3) more importantly, social media data is very complex which consists of network, text, tag, click and many other information. To achieve the abovementioned research goal, this dissertation proposes a research framework with three steps. First of all, this dissertation aims at detecting evolving user communities because of its broad applications in e-commerce, online social media, intelligent security, public health and more. We propose a Dynamic Stochastic Blockmodel with Temporal Dirichlet Process, which enables the detection of user communities and tracks their evolution simultaneously from a network stream. The number of user communities is automatically determined by a Recurrent Chinese Restaurant Process without any human intervention. In addition, the identified communities exhibit a rich-gets-richer effect and other beneficial properties. The experiment evaluations suggested the effectiveness of the proposed model. Secondly, instead of considering only network data, we take textual information and user interest into account to design a novel probabilistic graphical model which can detect interpretable and dynamic trends and topics from document streams, where each trend (short for trending story) corresponds to a series of continuing events or a storyline. Experiments on three different datasets indicated that our proposed model can capture meaningful topics and trends, monitor rise and fall of detected trends, and outperform baseline approach in terms of the perplexity on held-out dataset. Last but not least, to study the benefit of trend and topic modeling, we propose to adopt the user interests learnt from social media documents, which are typically contributed collaboratively by Web users, to improve the performance of recommendation in social media. To achieve this research goal, we introduced two reranking models, which combine the power of bipartite graph based collaborative filtering and user interest detected by a probabilistic graphical model, to rank social media documents. Our proposed approaches successfully make use of the user interest extracted from social media data to address the cold star issue. Experiment results on a public dataset demonstrated the effectiveness of the proposed techniques.
The Role of Leadership in Starting and Operating Blended Learning Charter Schools
Authors:   , Agostini Michael Eric , Geller Kathy Dee
Published: July 2021

Heavily utilizing both instructional technology and face-to-face instruction within a bricks-and-mortar school environment, blended learning charter schools are gaining attention as a cost-effective school design. As educators turn to these blended learning school models to improve both the operational efficiency and student outcomes of Americas public schools, prior research suggests a shortage of school leaders who sufficiently possess the skills and knowledge to effectively start and operate the technology-driven schools. Using a multisite, case study approach to examine the leadership of three blended learning charter schools in California, this study sought to answer the following questions: What are the biggest challenges founders of blended learning charter schools identify in their attempts to start a blended learning charter school? What are the particular skills and knowledge these founders have had to rely on or develop in order to design and start their blended learning schools? When hiring their school leaders, what particular skills and knowledge do the founders of blended learning charter schools seek and how do these desired qualifications differ from traditional public schools leaders? School leaders of the blended learning charter schools in this study described a multitude of people-, operation-, and resource-related challenges they faced in starting their schools, many of which appear particular to establishing a blended learning instructional program. While leaders of these schools relied on many of the same leadership skills required by school leaders of traditional public schools, the blended learning charter school leaders in this study identified numerous skills that appear either unique to blended learning or are used to a much greater degree at blended learning schools. School leaders emphasized, among other skills, the importance of being able to use data, technology, instructional staff, and other resources to individualize student learning. In addition, school leaders described the difficulty they faced in identifying future leaders. Participants in this study bemoaned the quality and relevance of school leadership certification programs and, consequently, described relying on internal strategies for grooming their future school leaders.