bluuebunny/crossref_metadata_2025 huggingface dataset:
Elastic behavior of 3-D braided composites under compressive loading
Authors:   , Liao David , Ko Frank K , Tan Tein-Min
Published: July 2024

In this study, a systematically conducted experiment has been carried out to characterize the compressive properties of 3-D braided composites. Two analytical models have also been modified and incorporated into finite element codes to predict the elastic behavior of 3-D braided composites under compressive loading. On the experimental characterization, three different composite systems, each reinforced by carbon, S-2 glass and Kevlar fibers, respectively, were employed to study the material effect on the compressive properties. Four different braided structures were used to study the effect of fiber architecture. In addition, two compression test fixtures, namely, the shear-loaded fixture (IITRI) and the end-loaded fixture, were used. The experimental results reveal that fiber architecture plays a significant role in carbon and S-2 glass braided composites under compressive loading. Kevlar composites are not sensitive to fiber architecture. The compressive strength and modulus of braided composites are comparable with those of equivalent (+/-[theta]/0) laminates. In theoretical analysis, two models are used to predict the elastic behavior of 3-D braided composites under compressive loading. The Fabric Geometry Model (FGM) based on the micromechanics of composite materials and the Finite Cell Model (FCM) based on a frame-truss structural finite element method have been modified and implemented into finite element codes. In general, Fabric Geometry Model is seen to yield much better predictions than Finite Cell Model does. For carbon and S-2 glass braided composites, FGM predictions of all properties agree quite well with the experimental results for all four different braiding percentages. FCM, on the other hand, works only for composites with lower (i.e., 25% or 50%) braiding percentage. Besides, neither FGM or FCM does not account the non-linear behavior of Kevlar braided composites.
Heterogeneous nucleation of Sickle Hemoglobin
Authors:   , Mirchev Rossen , Ferrone Frank Anthony
Published: July 2024

Sickle Hemoglobin molecules assemble into polymers composed of seven helically twisted double strands. Intermolecular contacts within the double strands are well established. We show that the same contact sites are present at the polymer surface on four molecules in each layer, and demonstrate that the identical contact geometry can be achieved between fibers. This provides a structural rationale for the exponential polymer growth that characterizes the kinetics of gelation. This also gives a structural basis for the cross-linking which solidifies the gel. The thermodynamical characteristics of polymerization are elucidated by the double nucleation model, which assumes two ways of polymerization-homogeneous and heterogeneous. Introducing the predictions from our structural model into the theoretical description of the double nucleation model, we develop a new way of data analysis for calculation of the heterogeneous nucleation rate, the size of the nucleus, and the heterogeneous nucleation sites availability. This is verified against results from Sickle Hemoglobin experiments. Having the theoretical tools, we test the viability of our model experimentally. Since the mutation is on both [beta]-chains of the Sickle Hemoglobin tetramer, replacement of one of them with normal [beta]-chain will reduce the number of polymerization sites but not inhibit gelation. We measure the nucleation rates of Hemoglobin with one normal and one mutant [beta]-chain, cross-linked for stability. The results show twofold increase of the nucleus size, 10³-10⁴ times smaller homogeneous nucleation rate, 10²-10³ times smaller heterogeneous nucleation rate, and significant decrease with strong temperature dependence of the heterogeneous nucleation site availability which varies 14 orders of magnitude over a 10°C temperature range.
On design, yarn architecture and mechanical behavior of 3D braided composites
Authors:   , Kumar Amrita , Wang Albert S. D.
Published: July 2024

In recent years three-dimensional (3-D) braiding has emerged as a viable method for the fabrication of monolithic, near-net shape structures with 3-D fiber reinforcement. The premise of this thesis is to investigate the interrelationships between design, fabrication, testing and analytical modeling of these braided composite shapes. The investigative approach taken begins with the design of the 3-D braiding apparatus, the actual braiding of the preforms, their consolidation into composite specimens followed by mechanical testing and measurement of the resulting properties. Concurrently, analytical modeling of each of these developmental stages was carried out in close coordination with numerical simulation of the actual situations. Several structural shapes with varying degrees of complexity were designed and braided using different fiber systems; the braiding methodology used in the making of the complex-shaped preforms was developed based on the existing four-step 1x1 braiding process; the braided preforms were consolidated with a resin matrix using the Resin Transfer Molding process to yield the final composite specimens. A descriptive methodology to analyze the yarn architecture of these composites was developed based on the design and braiding processes; the unit-cells and cell-composition of the composite were determined from the yarn architecture and were used in micromechanics models for the prediction of local (unit-cell) and global (cell-composition) properties. The mechanical properties predicted by these models were correlated with experimental data obtained under conditions of axial loading and pure bending. A Scanning Electron Microscopic analysis of the failure modes associated with the tested specimens under conditions of pure bending led to the establishment of a preliminary failure criterion.
Development of a radiochromic film scanner to measure steep dose gradients around brachytherapy sources
Authors:   , Sullivan Paul Robert , Simpson Larry D.
Published: July 2024

The emergence of sophisticated treatment procedures and new radioactive isotopes in radiation oncology has challenged medical physicists to measure dose in the near-zone of brachytherapy sources. To accurately measure dose in these complex regions the dosimeter should possess high sensitivity, good spatial resolution, energy and dose-rate independence, and tissue equivalence. Gafchromic MD-55 film possesses many of these dosimetric characteristics and is currently viewed as the "gold standard" for measuring dose in the near-zone of brachytherapy sources. This project has custom-built a radiochromic film scanner to extract dose information from Gafchromic film dosimeters. The laser-based scanning system operates at 670 nm or 633 nm and provides accurate control of light power, light polarization, and film positioning during scanning. Gafchromic MD-55 film was used in conjunction with the laser scanner to measure the radial dose of both 90Sr and 125I brachytherapy sources. The 90Sr source investigated was a custom-designed planar applicator used to treat a variety of ophthalmic diseases. The 125I source was a Nycomed-Amersham (Model 6711) design that is in widespread clinical radiation oncology use. Results indicate that the manufacturer stated dose rates for the 90Sr applicator significantly underestimate dose in the near-zone. At typical calibration distances of 2 mm, the Gafchromic dose-rate results are 40% higher than those quoted by the manufacturer. 125I radial dose profiles are in agreement with the benchmark Monte Carlo data of Williamson. These results extend reliable near-zone data for 125 I from 3 mm down to 1 mm. This project has also discovered that laser-based densitometers using laser diodes (670 nm) and helium neon lasers (633 nm) may further polymerize Gafchromic film. The light induced coloration is irreversible and shows dependence on laser power, wavelength, dwell time and prior radiation dose of the film. The results demonstrate that laser powers as low as 0.1 mW produce a non-linear increase in the optical density of the film. Laser light-induced coloration can have a significant impact on practical Gafchromic film dosimetry.
Three essays on closed-end country funds
Authors:   , Kim Doseong , Chiang Thomas Chi-Nan
Published: July 2024

In this dissertation, we investigate the pricing of country funds in the US market and the time-varying behavior of country-fund premiums by applying weekly data of 47 country funds. Essay 1 examines country-fund price behavior in relation to corresponding NAV, foreign stock index, and the US stock index. The significance test and specification test unambiguously conclude that applying the information of NAV in the error correction framework to predict the country-fund price movements appears to be more appropriate since this model contains not only the short-run dynamic impact, but also the long-run equilibrium value. Examining the impact of the Asia crisis, the estimated coefficients had more dramatic change during the turbulent period although the sign and qualitative results remain the same. In Essay 2, we propose a time-varying risk hypothesis that relates country-fund discounts to stock-market risk and exchange-rate risk. Using the conditional variance of returns as a measure of risk, we find significant evidence to support the time-varying risk hypothesis. In particular, country-fund premiums are negatively correlated with the expected variance of country-fund returns and positively related to that of NAV returns. Country-fund premiums also relate significantly to the volatility of foreign exchange returns in the majority of cases. On examining the impact of the Asian crisis, most country funds are traded with a larger discount, but premiums are found in most Asian country funds that were severely hit by the Asian crisis. In Essay 3, we investigate the pricing of country funds in the US market, employing various US and foreign market factors, such as stock market returns and volatility, fund premium, and foreign exchange return and volatility. The evidence suggests that the US and foreign stock-market return, one-period lagged fund premium, and changes in exchange rates play a significant role in determining country-fund prices. Also, conditional variances of the US and foreign market returns and foreign exchange returns have moderate power to explain the country-fund returns. Finally, empirical findings indicate that the Asian crisis has had a significant impact on the relationship between fund returns and suggested factors.
Effects of varying initial appointment delays on intake attendance, tenure, and outcome in outpatient cocaine treatment
Authors:   , Festinger David Solomon , Lamb R J , Nezu Christine M.
Published: July 2024

Previous studies investigating the effects of appointment delay on initial attendance to out-patient drug-treatment indicate that offering clients earlier appointments increases initial attendance. Without exception, these investigations were either correlational, or have only two conditions, one immediate or early and one later. Thus, these studies were unable to identify the relationship between appointment delay and attendance of the initial appointment. The present study used an experimental design with four different delays in an effort to isolate this relationship. In the study, 116 clients calling an urban, outpatient cocaine treatment clinic to schedule initial appointments were randomly assigned to appointments either the same day, one-day, three-days, or seven-days later. Of the 116 subjects, 60 (51.7%) showed for their initial appointments. Chi-square analysis indicated an unequal distribution with a greater percentage of one-day subjects attending their initial appointments, 21 (72%); compared to same-day 16 (55%); three-day 12 (41%), and seven-day subjects 11 (38%). Client characteristics including age, gender, marital status, number of days since last use of cocaine, and comorbid abuse of alcohol, marijuana, or heroin, had no significant effect on intake attendance. Of the 60 clients who attended their initial appointments, there were no significant between group differences on mean length of time in treatment, mean number of counseling sessions attended, mean number of cocaine-free urines provided while in treatment, or on the Addiction Severity Indexes (ASI) severity of drug use composite at 3 month follow-up. In summary, the relationship between initial attendance and appointment delay appears to be an inverted-U-shaped function that peaks in this population at the one-day delay. Further, clients accepting the one-day appointments are likely to do at least as well and remain in treatment at least as long as those scheduled to different delays, and thus, the additional clients brought into treatment by optimizing intake delay appear to do at least as well in treatment as those not requiring this manipulation to assure their initial attendance.
The Influence of Signaling Networks on the Pathogenesis of Cancers of the Lung
Authors:   , Beck Tim Nico , Golemis Erica
Published: July 2024

Lung cancer is the leading cause of cancer related mortality and head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer globally. Both cancers are still not fully understood on a molecular level and treatment efforts frequently fail to cure patients. Analysis of broad signaling networks can provide new insights and is particularly powerful in combination with annotated patient data. We took advantage of available 'omics' databases to augment the study of Anti-Müllerian Hormone (AMH) and its receptor (AMHR2) - two proteins we identified as expressed and active in lung cancer - and of retinoblastoma 1 (RB1) associated cell cycle regulation. To better understand the importance of RB1 activity in HPV-negative HNSCC, we investigated the prognostic value of inhibitory CDK4/6 phosphorylation of RB1 on threonine 356 (T356) in archival HPV-negative tumor specimens from patients who underwent surgical resection and received adjuvant radiation. pT356RB1 was identified as a potential prognostic biomarker and a potential response predictor for CDK4/6 inhibitors. Regarding AMH and AMHR2, we discovered that 6-8% of non-small cell lung cancers express high levels of AMH or AMHR2. Furthermore, we were able to show that AMH/AMHR2 participate in a TGF-b/BMP signaling network and regulates epithelial-mesenchymal transition (EMT) in lung cancer. EMT is related to cancer cell metastasis and resistant to therapy, two dominant drivers of cancer mortality. In summary, we used publically available databases to augment the study of RB1 and AMH/AMHR2, with the goal to better understand the pathogenesis of cancers of the lung, head and neck.
A boundary element method for two-dimensional static piezoelectric problems
Authors:   , Zu Wenhong
Published: July 2024

Piezoelectric materials (PEM) are extensively used in modern technology to convert mechanical energy into electrical energy and vice versa. The importance of this unique characteristic is reflected in the growing number of cutting edge technologies using these materials in such industries as electronic packaging, medical instrumentation, automotive, aerospace and energy distribution. In most of these applications the electrical and mechanical reliability of structures and devices has become a major concern. Indeed, severe loading conditions and the unavoidable presence of defects due to manufacturing processes have increased the likelihood of damage or failure of piezoelectric-based devices and structures. As a consequence, many researchers have been developing theoretical and experimental techniques to better understand the behavior of PEM under severe loading conditions. However, very few boundary value problems have been analyzed in closed form due to the inherent mathematical complexities resulting from material anisotropy and strong electro-elastic interactions. Thus the need for efficient computational techniques. The present work introduces the boundary element method (BEM) as one computational alternative to address piezoelectric problems. In the process, we have derived new representation formulas, fundamental solutions (Green's functions) and boundary integral equations within the framework of two-dimensional electro-elastostatics. The mathematical developments have been implemented in a numerical algorithm which is tested for the solution of several boundary value problems of crucial importance in technology. The results show the excellent accuracy of the method and its economic features in terms of computer memory allocation and computational time.
A Generalized Framework for Computational Antibody Design
Authors:   , Adolf-Bryfogle Jared , Dunbrack Roland L.
Published: July 2024

A novel knowledge-based computational antibody design methodology an application have been developed for the design of antibodies and antibody therapeutics to targets of interest. It has been rigorously benchmarked to reproduce native antibody structures and sequences, and has been used to successfully design an antibody to a target antigen as a proof of concept of de novo design. Our lab's recent clustering of the structures of antibody Complementary Determining Regions (CDRs) in the Protein Data Bank (PDB) enabled the development of the antibody analysis software and database, PyIgClassify, which forms the core of this knowledge-based approach where we use the structural clusters and associated sequence profiles to guide design. The Program uses the Rosetta energy function and new methods for reliable CDR grafting, cluster-based constraints, profile-based sequence design, and flexible-backbone design to computationally test hundreds of thousands of prospective antibody designs in the span of days. Methods were developed for quickly analyzing structural properties of potential designs using the Rosetta FeatureReporter framework, while a Graphical User Interface (GUI), PyIgDesign, was created to aid in antibody design selection. The Rosetta Antibody Design (RAbD) program is meant to sample the diverse sequence, structure, and binding space of an antibody to an antigen. It was developed to enable near-complete customization for a variety of design strategies and projects and can design antibodies for a broad range of applications, from affinity of existing antibody-antigen complex structures to de novo design in which whole new sequences and antibody-antigen contacts are created.
Predicting level of independence following moderate and severe traumatic brain injury
Authors:   , Schatz Philip
Published: July 2024

Demographic and rehabilitation outcome data were analyzed for 300 moderate and severe traumatic brain injury patients enrolled in the Pennsylvania Head Injury Program (PHIP) between 1985 and 1994. Predictive factors of outcome following traumatic brain injury were identified. A ten-point level of independence rating scale was constructed as a measure for rehabilitation outcome, measuring need for supervision for: communication, self-care routines, basic living skills, daily living, and employment. Post-hoc interrater reliability was significantly high at.80. Multiple regression analysis identified Disability Rating Scale (DRS) scores at twelve to eighteen months post injury as the most significant predictor of level of independence up to nine years post injury. DRS scores accounted for 49% of the variance in the level of independence measure. Subjects matched for severity of injury and functional ability at discharge from primary rehabilitation were divided into groups on the basis of number of rehabilitation facilities attended. Analyses of variance revealed that subjects who attended fewer rehabilitation facilities spent significantly fewer days in primary rehabilitation and were more likely to be discharged to the care of their families. Subjects attending zero to three subsequent rehabilitation facilities after acute rehabilitation showed no significant difference on level of independence ratings, DRS scores, and Rancho Los Amigos Level of Cognitive Functioning ratings up to nine years post injury. It is hypothesized that subsequent rehabilitation hospitalizations do not significantly improve scores on outcome measures because these admissions occur in the absence of appropriate discharge placements following primary rehabilitation. Trends in acute and rehabilitation hospitalization statistics for TBI between 1986 and 1993 were analyzed. Analysis of trends in hospitalization statistics between 1986 and 1993 revealed significant decreases in mean acute care and rehabilitation length of stay (20 and 60 days, respectively) for TBI survivors, with no significant effect on level of independence.
Dynamic enhancement of semiconductor laser using external optical feedback
Authors:   , Ni Tsang-Der , Daryoush Afshin S.
Published: July 2024

Directly modulated fiberoptic links, because of their small size and low power consumption, are a clear choice for the distribution of signals to the active MMIC modules in antenna remoting applications. Previous attempts by many researchers have shown that the simultaneous improvement of laser bandwidth, linearity and noise characteristics is extremely challenging using the existing laser structure. To address this limitation, this thesis introduces a new approach for modifying the laser diode structure to attain a high modulation frequency, suppress intensity noise, and enhance dynamic range for baseband information. The new approach is based on the use of an external optical cavity to provide feedback of coherent light to the laser cavity. First, new rate equations were developed from Maxwell-Bloch equations, resulting in a model that overcomes the difficulties associated with phenomenologically modified standard rate equations. Phase and amplitude information on the feedback light and modulation frequency of the microwave signal were incorporated into the new equations. The model was then used for small-signal analysis and noise modeling. Experiments were conducted to verify the theoretical predictions. In these experiments, the measured threshold current reduction of the external cavity laser indicated the amount of feedback light in the active region of laser. A low frequency uncoated InGaAsP laser diode was used with an external cavity to attain higher microwave frequencies. In addition, laser nonlinearity was modified through a harmonic conversion process. Other experiments showed that the relative intensity noise of a laser with external optical feedback is significantly colored noise, due to the external optical feedback. More specifically, the relative intensity noise increases at the resonant frequency corresponding to the round-trip time delay in the external cavity. However, relative intensity noise is suppressed by about 20 dB to 40 dB at all non-resonant frequencies. Through the combination effective bandwidth increase and intensity noise reduction, the spurious free dynamic range improved at least by 8 dB over a broad bandwidth. Through this new approach, high quality data signals and high frequency reference signals can be simultaneously transmitted. This capability is highly attractive in applications such as the phased array antenna used in satellite communication.
Social problem solving skills in maltreating and comparison mothers
Authors:   , Cataldo Rosemarie , Shure Myrna B
Published: July 2024

The purpose of this study is to explore the relationship of problem-solving skills to child abuse. Problem-solving skill deficits related to parenting have been cited as a factor which can contribute to the development of physical abuse of children in the abuser. However, previous studies have limited their assessment of problem-solving ability to situations reflecting child rearing issues. This research was designed to substantiate previous findings and to extend past findings. This was accomplished by first, examining whether Maltreating mothers, as compared to Non-Maltreating mothers, demonstrate similar problem-solving deficits when confronted with social dilemmas involving adults. Specifically, the ability to generate alternative, relevant solutions was measured. Second, this research investigated whether Maltreating mothers differed from Non-Maltreating mothers in their general approach to solving problems. Specifically, problem-solving attitudes and the tendency to conceptualize problem-solving strategies were measured. The study involved a total of 37 maternal parents. Mothers belonged to one of two groups: (a) Maltreating (n = 18); or (b) Non-Maltreating (n = 19). The following problem-solving measures were used: Social Problem Solving Inventory; Parental Problem-Solving Measure; and the Alternative Solutions Adult Problem Stories. Results of one-tailed, Mann-Whitney U tests provided partial support for poorer problems-solving skills among Maltreating mothers, in comparison to Non-Maltreating mothers. Maltreating mothers tended to produce fewer solutions and were more likely to report use of solutions judged by raters to be less effective than those reported by Non-Maltreating mothers. The tendency to have an impulsive and careless problem-solving style was significantly greater among Maltreating mothers than among Non-Maltreating mothers.
Executive/board power and politics in strategic decision making
Authors:   , Simmers Claire A. , Hess Sidney W.
Published: July 2024

Corporate governance should benefit from increasing board involvement in the strategic decision process (SDP). However, little is known about board participation in this process. Power and politics between board members and executive directors in the SDP are studied using 140 senior officers in 17 Arts, Cultural, and Historical organizations in the Philadelphia-Delaware Valley area. Examined are two sets of relationships. The first set is between power (i.e. influence) and politics (i.e. collaborative or competitive behaviors) in five phases of the SDP (issue identification, alternative development, alternative evaluation and choice, implementation, and evaluation of results). Executive directors and board members share power; no relationships between power and politics are found. The second set of relationships is between politics and six outcome measures (quality, speed, goal achievement, average working capital, average working capital ratio, and unrestricted funds). Quality and speed are strongly related to collaborative politics; goal achievement and unrestricted funds are weakly associated with collaborative politics. I find no relationships between politics and either working capital measure.
The human ocular lens
Authors:   , Jacob Robert Francis , Mason R. Preston
Published: July 2024

The ocular lens is a transparent tissue that contributes to normal visual physiology by providing a means of transmitting and focusing light onto the retina. The lens is made up almost entirely of a large number of elongated, prismatic fiber cells that are compacted into highly ordered, concentric lamellae within the lens body. Fiber cells lose all subcellular organelles during their maturation; consequently, plasma membrane becomes essentially the only organelle of the lens. The fiber cell plasma membrane of the human ocular lens contains the highest relative amount of cholesterol known for mammalian cell membranes, with cholesterol/phospholipid (C/P) mole ratios ranging from 1 to 4. It was hypothesized that cholesterol, at these unusually high C/P mole ratios, organizes into discrete clusters or domains within the fiber cell plasma membrane. It was further hypothesized that reduced cholesterol content and lipid structural alterations, shown to occur in cataracts, perturb the structural organization of cholesterol in the lens membrane. To test these hypotheses, small angle x-ray diffraction approaches were used to directly examine the structural organization of lens fiber cell plasma membranes isolated from normal and cataractous human ocular lenses. Meridional diffraction patterns obtained from normal lens membranes demonstrated the presence of immiscible cholesterol bilayer domains, having a unit cell periodicity of 34.0 Å. These domains were observed in both cortical and nuclear fiber cell plasma membranes (2.4 and 3.3 C/P, respectively) and were shown to be stable over a broad range of temperature (5-40°C) and relative humidity (31-97%) levels. Similar analyses demonstrated that cataractous lens membranes, despite significantly lower (>50%) C/P mole ratios, contained more prominent and better-resolved cholesterol domains than non-cataractous controls. This paradoxical finding was consistent with the discovery that lipid peroxidation induces cholesterol domain formation in model membranes despite lower concentrations of cholesterol (0.4-0.8 C/P). These data (1) provide the first direct evidence for the existence of discrete cholesterol domains in fiber cell plasma membranes of the human ocular lens, (2) demonstrate that cholesterol domain formation increases in cataracts, and (3) suggest that lipid peroxidation may be an important mechanism by which cholesterol domain formation is enhanced in cataractogenesis.
Heterodimensional schottky contacts to modulation-doped heterojunction with application to photodetection
Authors:   , Seddik Amro Anwar , Nabet Bahram
Published: July 2024

The growing technological demand for high speed and compact integrated electronics and Optics is a pressing challenge. Speed and compactness necessitate low power consumption semiconductors with high transport mobility carriers, with potential of ultra large-scale integration of electronic and Optoelectronics circuitry. One avenue to fulfill these requirements is to utilize reduced dimensionality where carriers are spatially confined to less than three-dimensions, causing their energy levels to become quantized and their transport favorably affected. With recent progress in semiconductor growth and processing technologies low dimensionality has become practically realizable, this makes the study of contact properties to these systems increasingly important. In this work we study the contact between a low-dimensional semiconductor structure and a three-dimensional metal and the application of such a contact in photodetection. We theoretically derive the thermionic emission current for Schottky contact to two-dimensional and one-dimensional structures. The derivation underscores the discrete nature of low-dimensional structures and shows that the thermionic emission current is reduced by a factor exponentially proportional to the first quantized energy level. We also propose and formulate, for the first time, a physical phenomenon in two-dimensional structures created by modulation doping of a heterojunction, which is the effect of the cloud of electrons in the small bandgap material on the thermionic emission current. We have named this the electron-electron cloud effect; we show that this interaction increases the effective Schottky barrier height in a fashion counter to the image force lowering mechanism. In order to realize Schottky contact to low-dimensional structures, we have fabricated a novel Heterojunction Metal-Semiconductor-Metal (HMSM) photodetector. Experimental characterization and the general trends of the behavior of the HMSM devices are presented within the body of this thesis. We conclude by demonstrating other applications of such heterostructure, in particular, we present an optically and electrically gateable variable reactance device. Before we delve into introducing this study, we forward by an overview attempting to explore where such a study and similar like us as infinitesimal as it is might seem ties in the global picture of the propitious technological growth and how this technological development touches every humans kind life.
Ion exchange on a chelating resin
Authors:   , Klink Paula Rae , Haas Charles Nathan
Published: July 2024

Highly selective chelating ion exchange resins are an attractive option for metal removal from wastewater due to their ability to separate mixed metals for recovery and reuse. The ability of the chelating resin Amberlite® IRC-718 to separate copper, cadmium and sodium ions from solution has been experimentally examined. It was found this resin shows strong preference for copper over cadmium, and an even stronger preference for both of these ions over sodium. The adsorption isotherms for this resin are very non-ideal for the monovalent-bivalent pairings. A series of experiments containing all three ions was also performed. In addition, this work examines the performance of five literature models in representing the experimental data, notably their prediction of ternary behavior using parameters fit from binary data. All models were based on equilibrium partitioning of the ions between the resin and the solution, and varied in complexity using between one and four adjustable parameters. The Error in Variables method was used to estimate model parameters, and the resulting fit was subjected to rigorous statistical examination. The severe non-ideal behavior of the chelating resin presents a challenge for the models. The results were mixed: although the models represented the binary data adequately, statistical analysis suggested potential bias in the estimates, and the ternary predictions were generally poor. Possible explanations for these problems are presented. Data from literature were also examined to further evaluate and compare model performance. The ternary predictions were much closer to the experimental observations than for the chelating ion system. Thus it can be concluded that these models were successful at representing the data sets for various resin-ion systems to a degree sufficient for preliminary engineering design, and to reduce the number of experimental screening trials needed to develop multicomponent ion separation.
Rapid serial visual presentation (RSVP) for professional tasks
Authors:   , Sloane Elliot B. , Drott M. Carl
Published: July 2024

A high-resolution Rapid Serial Visual Presentation (RSVP) computer display system was used by domain-expert subjects to make relevance judgments about articles related to the subjects' own queries. The article title, abstract, and author fields were downloaded from Dialog databases and prepared as custom citations for review. This study used eight domain-expert subjects, actual work-related queries, and data from current publication databases to simulate real-world tasks. Approximately 100 citations per subject were viewed in groups of ten, and the experts used a 0-10 point magnitude scale to score the relevance of each citation to their query. The computer display resolution was 1600 x 1200 dots per inch. Standardized baseline reading speed, in words per minute (wpm), and comprehension and vocabulary grade level for each subject were established using the Nelson-Denny Reading Test. The experts scored one group of ten citations using Microsoft WORD, and then subsequent groups were scored using RSVP. In the RSVP mode, subjects viewed individual words, enlarged on the center of the computer screen, at rates beginning at their baseline rate (range: 154-339 wpm) and increasing in 150 wpm increments up to 1350 wpm. Subjects also scored the same citations a second time using laser printouts. Pearson r correlations between the computer-display-system and printout scores averaged 0.79 for WORD and 0.63 for RSVP for all display speeds. Using a paired t-test, the differences in the correlations were found not to be statistically significant, regardless of display speed. The conclusion was that the RSVP and WORD relevance judgment correlations were comparable to prior test-retest relevance judgments studies. These findings suggest that RSVP or WORD may be a successful alternative to printouts when using high-resolution displays. Because the correlation differences were not statistically significant at RSVP display rates up to 1350 wpm, future research was suggested to examine using RSVP displays to make the task of finding relevant articles more efficient for domain-expert users. Also, based on prior research, RSVP may prove similarly useful for sight-impaired and foreign-language domain-experts.
Non-invasive determination of blood pressure waveform from blood flow measurement
Authors:   , Liu Mao-Zu , Jaron Dov , Moore Thomas W
Published: July 2024

Arterial blood pressure can provide vital diagnostic and prognostic information on the state of the cardiovascular system. To date, most clinical non-invasive means of acquiring arterial blood pressure involve occlusive cuff procedures. While these methods provide a safe and reliable reading of systolic, mean, and diastolic pressure values, occlusive cuff methods cannot provide continuous blood pressure monitoring. When long term, continuous monitoring of arterial blood pressure is necessary, an invasive method of blood pressure measurement is often employed (i.e. catheterization). By using an invasive pressure transducer, monitoring can be continuous and the whole pressure waveform may be obtained. Analysis of the continuous pressure waveform can yield valuable information on the state of the cardiovascular system. However, catheterization is a procedure which presents some risks to the patient. The method for the acquisition of arterial blood pressure proposed in this paper is both noninvasive and non-occlusive. Based on the Navier-Stokes and the continuity equations of fluid flow, a transmission line model of a blood vessel is developed. The wave propagation coefficient is found using flow measurements at three sites along the vessel (such flow information can be obtained by non-invasive ultrasound methods.) From these data, the blood pressure waveform can be calculated. This method offers long term, continuous monitoring of the pressure waveform, while providing both the safety of indirect methods and the physiologic information of direct methods. This thesis reports a feasibility study of the procedure.
Collection overlap and coordinated collection development
Authors:   , Broadbent Harry Elvin
Published: July 2024

The thesis addresses a fundamental question of library cooperation: how, in resource sharing library networks, information about collection overlap may help the academic library manager to make decisions about a library's involvement in coordinated collection development for monographs. To achieve the objectives of this thesis it was necessary to study a population of monographic titles, held by a group of libraries, for which circulation histories would be available. Eight libraries were selected from among the Tri-State College Library Cooperative membership. They all supported independent colleges of liberal arts and sciences. A proportionate statistical sample was drawn from among the 1978 monographic acquisitions of the libraries. For each title there were three types of variables studied: title characteristics; circulation measures; and overlap, or holdings, measures. Sources of data were the OCLC database, inspection of titles in holding libraries, and Book Review holding libraries, and Book Review Index: A Master Cumulation, 1969-1979. There was little statistical support for hypotheses linking circulation to holdings. There was some correlation between holdings among the 8 libraries, holdings in the TCLC network, and holdings in Pennsylvania, but the 8 libraries held very few unique titles in relation to state-wide holdings. There was no difference in holdings levels by types of publishers; but by broad subject divisions, Science books were more widely held; and books reviewed in Choice were more widely held. There was a weak correlation between the number of reviews and holdings. Despite the similarity of academic programs among the 8 institutions there was little title overlap. The findings suggest that managers of the libraries studied will find little value in coordinated collection development programs which concern themselves with duplication of monographic titles.
Characterization of autoinducer-2 quorum sensing and the Lsr locus in Haemophilus influenzae
Authors:   , Janto Benjamin Armund , Ehrlich Garth D
Published: July 2024

The Lsr (LuxS-regulated) locus encodes genes that bind, import and process autoinducer-2 (AI-2), which is a quorum sensing (QS) molecule produced in a wide range of bacterial species. This operon was previously unknown among the non-typeable Haemophilus influenzae (NTHi) but through whole genome sequencing and comparative genomic hybridizations (CGH) I detected it in 43/187 (23%) of strains. A mutant was constructed from strain CZ4126/02 which lacks all nine Lsr genes. In minimal media the Lsr-KO showed a slight but consistent growth defect that was not observed in complex media. Using the Vibrio harveyi BB170 bioassay, AI-2 kinetics in WT and Lsr-KO strains were characterized. Production and uptake of AI-2 was determined to be highly dependent on media conditions (similar to growth) and in defined media strain CZ4126/02 was able to take up AI-2 in early stationary phase but the Lsr-KO was not. RNA samples were collected pre and post AI-2 uptake to determine what role the Lsr locus plays in global gene expression patterns. The NTHi supragenome chip, previously used for CGH, was established as a tool for transcriptional analyses by thorough replicate testing and development of an analysis software pipeline. Two major families of virulence factors were found to be under the control of the Lsr locus: the vHiSLR and Hgp (hemoglobin-binding proteins). Surprisingly, the data suggest that the regulation of these two virulence factors is independent of the AI-2 uptake event. Additional differentially regulated genes showed strong overlap with the regulon controlled by the nitrate/nitrite-controlled NarPQ two-component system. vHiSLR and Hgp proteins were also found to be differentially regulated between the WT and Lsr-KO strains by 2D-DIGE proteome comparisons. These results demonstrate that the Lsr operon is linked to major virulence factors (vHiSLR, Hgp) and a large anaerobic switch making it highly relevant in pathogenesis.
The impact of activity scheduling on activity level, negative symptoms and self-efficacy for individuals with schizophrenia
Authors:   , Lester Heather L. , Kloss Jacqueline D.
Published: July 2024

This study evaluated a treatment intervention that provided training in activity scheduling for individuals with schizophrenia. There were 16 people in the treatment group and 14 people in the control group. The treatment group received 6 weeks of training in activity scheduling. Activity level, negative symptoms, and self-efficacy were assessed at the start of the study (Time 1), after the treatment intervention (Time 2), and 2 weeks later (Time 3). Activity level was measured based on the amount of time the individual reported being engaged in scheduled activities over a 24-hour period. Negative symptoms were assessed using the Scale for the Assessment of Negative Symptoms (Andreasen, 1983). Self-efficacy was evaluated using the General Self-Efficacy Scale (Sherer, Maddux, Mercandante et al., 1982). The study hypotheses were not supported, as the results show no significant differences in treatment effect between the treatment and control groups. A review of participant characteristics and the structure of the treatment program suggest that limitations of the present may have been ameliorated by more specifically tailoring the treatment to the rehabilitation needs of each individual.
Age-related decrease in murine natural killer cell activity after interferon-[alpha]/[beta] stimulation
Authors:   , Plett Paul Artur , Murasko Donna
Published: July 2024

Natural Killer (NK) cells, important in viral infections and anti-tumor activity, show reduced cytotoxicity in aged mice. A mechanism for the age-related decline has not been clearly established. IFN-[alpha]/[beta], a cytokine that is involved in the natural defense against viral infections can also have anti-tumor activity in part by activating NK cell cytotoxicity in vitro and in vivo against NK sensitive targets. We therefore assessed changes in NK cytotoxicity in spleen and peripheral blood cells after IFN-[alpha]/[beta] stimulation, in adult (6 months) and aged (22-26 months) C57Bl/6 (B6), Balb/c and C57Bl/6xBalb/c-F1 (CB6-F1) hybrid mice. Aged B6 and Balb/c mice had a significantly reduced IFN-[alpha]/[beta]-stimulated NK cytotoxicity compared to adult mice. The CB6-F1 hybrid mice however, showed similar NK cytotoxicity after IFN-[alpha]/[beta] induction in adult and aged mice, suggesting the possibility of genetic complementation of possible defects in the parental strains. We showed that the decreased induction of NK activity by IFN-[alpha]/[beta] did not appear to be the result of suppressive activity of adherent cells or T cells. The reduced cytotoxicity aged mice was also not due to altered number of NK cells, since the percentage of NK cells (NK1.1+) of splenic and peripheral blood lymphocytes was similar in adult and aged B6 mice. Flow cytometric analysis revealed that aged mice had a higher expression of the IFN-[alpha]/[beta] receptor1, but showed similar levels of IFN-[alpha]/[beta] binding than adult mice. An increased amount of IFN-[alpha]/[beta] or a longer period of treatment with IFN-[alpha]/[beta] did not elevate NK cytotoxicity in aged mice. A higher expression of the apoptosis receptor Fas and increased target-induced apoptosis in aged compared to adult mice, suggested that a greater number of NK cells in aged mice were dying upon IFN-[alpha]/[beta] activation and target interaction. Co-stimulation with phorbol ester (PMA), significantly increased the percentage of NK cells producing IFN-[gamma] and also increased activation markers CD69 and CD25 expression similarly in adult and aged mice. NK cytotoxicity however, was significantly reduced in aged mice, suggesting a dissociation between the increase in activation markers and the reduced NK cytotoxicity after IFN-[alpha]/[beta] in aged mice. Finally we observed that a subset of NK cells, NK1.1+CD8+, was significantly increased in aged B6 mice and the percentage of NK1.1+CD8+ cells was inversely related to IFN-[alpha]/[beta] induced cytotoxicity. These results indicate that the decreased activation of NK activity in aged B6 mice is reflected in altered IFN-[alpha]/[beta] receptor expression, cytokine production and apoptosis in aged mice. These innate changes in the NK cells in addition to the increased percentage of NK1.1+CD8+ cells in aged mice, may be responsible for the reduced inducibility of NK cytotoxicity after IFN-[alpha]/[beta] stimulation.