eChirp: Measuring Available Bandwidth for the Internet Using Multiple Chirp Packet Trains

Measuring available bandwidth over a network path in the Internet is a challenging research problem. In this thesis we have studied this problem and developed a new technique called "eChirp". First, the effectiveness of pathChirp [1] is studied in terms of model performance of chirp packet train structure, actual bandwidth, queuing delay and excursion segmentation. Then we remodeled the chirp train structure. The eChirp can measure the available bandwidth over a network path efficiently and accurately with heavy and light load links. To measure the available bandwidth, the packet probing rate configuration used in pathChirp technique is modified by changing its chirp train structure. The modified structure uses multiple chirp trains (three trains) that provides better probing rate configuration and ultimately gives better bandwidth measurement. Per-packet available bandwidth is calculated using weighted average of per-packet bandwidth of three trains. We also determined the bounds of probing rate parameter which was questionable in pathChirp and affects the available bandwidth measurement accuracy. The eChirp technique has been experimented with numerous network path topologies with low and high link loads with CBR cross-traffic conditions using NS-2 simulated network and results are compared with most recent pathChirp technique. Simulation results show that the proposed eChirp technique is better than pathChirp scheme in terms of estimating available bandwidth

Experimental and computational strategies for enhancing mass transport and cryopreservation of biological tissues

A bioreactor is a large-scale engineered in vitro device that maintains a 3D arrangement of functioning cells for use in various bioengineering applications. The current work is focused on heat and mass transfer issues related to the bioreactor's performance and applications. Firstly, for bioreactors to achieve high functional output, the cells within its 3D tissues constructs must have adequate supplies of nutrients and gases (O2, CO 2 etc). Among these, O2 transport has been a major challenge since regions of hyperoxia and hypoxia can develop. Hence, in the first phase of this work, an O2 transport based computational model is proposed to help simulate the distribution of O2 through the volume of the 3D tissue constructs under various operational conditions. The advantage of such a predictive model is that it can supply preliminary data, helpful for optimizing O2 delivery to the cells. Secondly, the off the shelf availability of the cells and tissues utilized in the bioreactors is maintained mainly through cryopreservation techniques. In the case of large tissues, cryopreservation success is governed by the cryopreservation protocol used. Therefore, in the second phase of this work, a user friendly computational tool able to predict and compare the effectiveness of various cryopreservation protocols is developed. The computational tool's predictions are briefly validated against experimental results to verify its predictive accuracy. The package is designed to offer a cost effective solution for designing protocol's for cryopreserving 3D tissues and tissue equivalent. Thirdly, with specific relevance to the cryopreservation of liver cells and tissues, it was hypothesized that increased aquaporin (AQP) (integral membrane proteins which aid water transport) expressions on the cellular membrane would improve cellular water transport and thereby improve the cryopreservation efficiency. Experimental results showed increased cell viability following cryopreservation of liver tissues equivalents treated for translocation of AQPs to the cellular membrane, thus confirming the hypothesis to be true. Overall, the computational and experimental strategies proposed in the current work would help enhance heat and mass transport to biological tissues, resulting in potential improvement in the performance of bioreactors and other large scale tissue replacement systems

Web 2.0 technologies for effective knowledge management in organizations: a qualitative analysis

A new generation of Internet-based collaborative tools, commonly known as Web 2.0, has increased in popularity, availability, and power in the last few years (Kane and Fichman, 2009). Web 2.0 is a set of Internet-based applications that harness network effects by facilitating collaborative and participative computing (O'Reilly, 2006). Conceptually, Web 2.0--with its ability to combine traditional KM tools' features with social computing, where knowledge is evolved through social interactions (Parameswaran, 2007)--has been identified as an effective KM paradigm (Fitch, 2007; Mindel and Verma, 2006).With such a capability, Web 2.0 technology has the potential to address many of the KM challenges that organizations face (Minocha and Thomas, 2007; Wagner, 2006). While Web 2.0 has gained widespread popularity at the consumer level, it is still not well-understood how Web 2.0 can be effectively used for KM by enterprises. In our research, we address this critical gap in the literature by using a multiple-case research design. This dissertation examines how IT organizations use Web 2.0 technologies for Knowledge Management (KM) at the individual, project, and group level. We also investigate how the use of Web 2.0 technology for KM affects organization, group, project, and individual level outcomes. Using multiple case research design, this research provides examples of effective use of Web 2.0 for KM at the individual, project, group, and organization level. Using empirical data, this research also establishes a relationship between the uses of Web 2.0 for KM and its effects on individual, project, group, and organization levels. The extant literature has yet to examine such relationships

ROLES OF SCHOOL DISTRICT COMPETITION AND POLITICAL INSTITUTIONS IN PUBLIC SCHOOL SPENDING AND STUDENT ACHIEVEMENT

Equity in school district spending, and equity and productive efficiency in educational outcomes are of paramount importance in the literature on K-12 public education in the US. The research on the effects of school choice (operationalized as inter-school district competition) and local political institutions on unequal school district spending and equity and productive efficiency in educational outcomes is not adequate. This dissertation fills several gaps in the literature by 1) extending the literature on the Public Choice, the Leviathan, the Consolidated Local Government, and the Reformism models that examines the interactive roles of local political institutions and school choice on equity in spending, productive efficiency and equity in student achievement in public schools in metropolitan areas; and 2) modeling the equity effects of school choice and political institutions on school district spending and student achievement. Fixed effects, instrumental variable fixed effects, Hausman-Taylor regression, and Multilevel Linear regression models are utilized on a uniquely compiled longitudinal dataset from several sources, including the Popularly Elected Officials Survey from the US Census Bureau, the Local Education Agency (School District) Longitudinal Finance Survey, the National Education Longitudinal Study (NELS: 1988-92), and the School District Demographics System from the National Center for Education Statistics. Results from fixed effects models lend support for interactive effects of political institutions and inter-school district competition on school district spending. Additive and interactive models do not robustly support the equity effects of inter-school district competition on school district spending. However, results from fixed effects and instrumental variable fixed effects models support the equity effects of political institutions on school district spending in some cases. School districts with more professional political institutions are also more equitable in public education spending. Results show that whereas inter-school district competition has productive efficiency effects on student achievement the political institutions do not. In terms of equity, the inter-school district competition and political institutions have differential effects on student achievement. In regard to the former, results imply that the increased inter-school district competition leads to inequity in students' 10th grade reading scores and 12th grade reading and math scores. In regard to the latter, results suggest that differences in political institutions across school districts lead to inequity in students' 10th and 12th grade reading and math scores. School districts with more professional political institutions also have more equitable student achievement. Student's reading and math scores are generally higher in comparatively higher income quintile school districts than those in comparatively lower income quintile school districts. These findings assume significance as they inform the policymakers in regard to why and how organizational and political contexts matter in bringing desirable educational outcomes. The policymakers can bring organizational and political changes in school districts for achieving the goal of more effective public education

Multi-scale data fusion for surface metrology

The major trends in manufacturing are miniaturization, convergence of the traditional research fields and creation of interdisciplinary research areas. These trends have resulted in the development of multi-scale models and multi-scale surfaces to optimize the performance. Multi-scale surfaces that exhibit specific properties at different scales for a specific purpose require multi-scale measurement and characterization. Researchers and instrument developers have developed instruments that are able to perform measurements at multiple scales but lack the much required multi- scale characterization capability. The primary focus of this research was to explore possible multi-scale data fusion strategies and options for surface metrology domain and to develop enabling software tools in order to obtain effective multi-scale surface characterization, maximizing fidelity while minimizing measurement cost and time. This research effort explored the fusion strategies for surface metrology domain and narrowed the focus on Discrete Wavelet Frame (DWF) based multi-scale decomposition. An optimized multi-scale data fusion strategy ‘FWR method’ was developed and was successfully demonstrated on both high aspect ratio surfaces and non-planar surfaces. It was demonstrated that the datum features can be effectively characterized at a lower resolution using one system (Vision CMM) and the actual features of interest could be characterized at a higher resolution using another system (Coherence Scanning Interferometer) with higher capability while minimizing the measurement time

Effects of açaí berry (Euterpe oleracea) extracts on human antioxidant systems and drug metabolism

The source and sink of reactive oxygen species are diverse and so are the control mechanisms to counteract them. Sources may be exogenous or endogenous from normal metabolic pathways. Similarly, the sink could be a simple radical scavenging event by small molecule antioxidants and antioxidant enzymes or complex events involving cellular signaling processes. The effects of reactive oxygen species may precipitate cellular dysfunction from its toxicity, protect from invading microorganisms or perform essential functions through regulation of cell signaling pathways. Excessive Reactive oxygen species leads to oxidative stress which mediates cellular damage and is implicated in several pathological conditions. The current research addresses biological systems that may effect redox balance in humans. One goal of the current research was to establish structure activity relationship for substrate binding to several human drug metabolizing enzymes implicated in reactive oxygen species generation, namely CYP2A6 and CYP2E1. The substrate dynamics of these two enzymes were studied by probing the active site with a series of small chain saturated and 2,3-unsaturated aldehydes using human liver microsomes. The study demonstrated that the aldehydes inhibited both the enzymes in competitive manner with unsaturated aldehydes being more potent than their saturated counterparts. The potential for p-stacking interactions between the phenylalanine rich active site of these enzymes and the double bond at 2-position in unsaturated aldehydes conferred high affinity for these aldehydes. It also confirmed an earlier findings that the active site of CYP2A6 is rigid where as CYP2E1 is flexible due to the presence of extended p-system allowing the expansion of its active site. Another goal was to examine the possible interactions between human cytochrome P450 enzymes of pharmacological and toxicological importance with a natural product called açaí. Açaí (Euterpe oleracea) is a Brazilian palm tree that has emerged from traditional medicinal plant to a recent super-fruit status. The assumption that it is safe to consume açaí currently lacks evidence from its interactions with drug metabolizing cytochrome P450 enzymes. The interaction between the crude extracts of açaí and major cytochrome P450 enzymes involved in drug metabolism and toxicology demonstrated the potential for chloroform extract to inhibit the isoforms CYP1A1, CYP2B6 and CYP2C8. The Michaelis-Menten Kinetics studies indicated mixed mode of inhibition of these enzymes by crude chloroform extract of açaí with low KI and KI’ values for CYP2C8 followed by CYP2B6 and CYP1A1. In addition, the study was extended to identification of inhibitors for toxicologically important CYP2A6 and CYP2E1 using a collaborative bioassay-guided fractionation approach. Although the crude chloroform extract of açaí showed considerable inhibition of these enzymes, specific inhibitors were not identified. Finally, the regulation of a signal transduction pathway namely Nrf2/ARE signaling pathway by açaí constituents was also studied as a potential strategy to prevent oxidative damage. The nuclear factor erythoid 2-related factor 2 (Nrf2)-antioxidant response element (ARE) pathway is a cellular defense to counteract oxidative stress. Activation of this pathway increases the expression of a battery of antioxidant genes. This was achieved by monitoring the activation of a cis¬-acting DNA sequence referred to as Antioxidant Response Element (ARE) contained in a luciferase-containing promoter vector in cultured HepG2 cells. A high-throughput analysis of fractions generated using bioassay-guided fractionation of açaí has resulted in the identification of a class of compounds known as Pheophorbides as the inducers of ARE-luciferase. Dose response analysis using pure compounds demonstrated significant induction of ARE-luciferase at concentrations as low as 8.2 µM and 16.9µM for Pheophorbide a methyl ester and Pheophorbide a, respectively

Chemical Composition and Anti-proliferative Activity of Several Medicinal Plants

Plants are valuable sources of medicinal compounds and their use for healing is well known from ancient times. Natural drugs obtained from plants represent about 25% of the prescription drug market in the United States. Plants have a long history of use in the treatment of various cancer types. Currently, 60% of the anticancer agents available in the market are derived from natural sources. Since phytoconstituents play a vital role in the discovery of various anticancer drugs, they have been chosen as the area of focus for our research. In this proposed study, four medicinal plants with reported anticancer activity were selected (Hydrastis canadensis, Curcuma longa, Zingiber officinalis, and Alpinia officinarum). All these plants were extracted by percolation and tested for anti-proliferative activity against Dictyostelium cells. C. longa, Z. officinalis and A. officinarum organic extracts all showed significant anti-proliferative activity in this preliminary bioassay. Of the three active extracts, the turmeric extract was chosen for further investigation because of its great historical significance and the promising results of recent phase I clinical trials. Using flash chromatography, a total of nine fractions were obtained from the complex C. longa organic extract. Curcumin in these fractions was identified and quantified using high performance liquid chromatography - electrospray ionization mass spectrometry (HPLC-ESI-MS). Other active components (demethoxycurcumin, bisdemethoxycurcumin and ar-tumerone) were also characterized using the same system. All these fractions were then tested for in vitro anti-proliferative activity against MCF-7 cells using the XTT assay to determine whether activity correlates with the presence of curcumin in the fractions, or whether other (perhaps unidentified) compounds are involved. The results indicated that the major component curcumin was responsible for the majority of the anti-proliferative activity of the complex turmeric extract. Although no synergistic activity was seen for the various constituents present in the complex extract in this case, a novel approach for probing potential synergistic or additive effects was demonstrated. This approach could be applied to future investigations of synergistic or additive activity of medicinal plants

The role of shame within the context of familism in emerging adults

Shame, in contrast to guilt, has typically been seen as a deleterious emotional experience associated with negative psychosocial outcomes across development. Despite this dominant model of shame, a growing body of evidence has highlighted the unique ways that this self-conscious emotion functions in collectivistically-minded cultures and families. This study sought to elucidate how family-based shame operates within the context of one such collectivistic value (familism), with a particular focus on the conditions under which shame may serve an adaptive or prosocial purpose. To answer the question, a person-centered approach was utilized to examine patterns of family-based shame, familism cultural values, and rumination in an ethnically diverse sample of college students (N = 654). Latent profile analysis suggests three patterns in the data, with participants high in family-based shame showing significant associations with higher depressive symptoms, but not lower academic performance, when accompanied by high rumination and familism value endorsement

Design of a cost effective battery-supercapacitor hybrid energy storage system for hourly dispatching solar PV power

This study aims to develop a low cost energy storage system for hourly dispatching solar photovoltaic (PV) power for 1MW grid connected PV array. To fulfill this objective, the optimum (most economical) scaling of a battery and supercapacitor (SC) hybrid storage is developed based on the time constant of a low pass filter (LPF) that is used to allocate the power between a battery and SC. Based on the battery state of charge (SOC), rule based algorithms are developed to estimate the perfect grid reference power for each one-hour dispatching period. Another rule-based algorithm is implemented to keep the battery SOC within a certain limit that helps to increase the battery lifetime. An economic comparison of different kinds of battery and SC combination in hybrid energy storage system (HESS) is presented in this research. This study also considers the relationship between the actual PV cell temperature and the ambient temperature and presents their effects on energy storage price calculations. This study uses actual solar data of four different days recorded at Oak Ridge National Laboratory (ORNL) in MATLAB/Simulink environment simulations to get the better picture about annual energy storage cost for hourly dispatching solar power. According to the results, the HESS combination of li-ion battery and SC, outperforms a battery only or lead acid and SC combination in HESS operation regardless of temperature framework

Effect of Particle Size on the Structural and Magnetic Properties of Nanocrystalline Zinc Ferrite

ZnFe2O4 is one of the most important technological material having applications in radio engineering, radio technology, semiconductors, bio-medical applications etc. ZnFe2O4 when in bulk form shows paramagnetic behavior at room temperature. When ZnFe2O4 is synthesized by some techniques it was possible to see the ferromagnetic behavior. Also, ZnFe2O4 in nanocrystalline form exhibit different magnetic properties. Therefore in the present work we intend to present the properties of particle size behavior of ZnFe2O4 nanoparticles. ZnFe2O4 nanoparticles were synthesized by oxalic acid based precursor method. The obtained ZnFe2O4 nano powders were thermally annealed from 300 to 600 °C. The structural and magnetic characterization were measured using X-ray diffraction (XRD), scanning electron microscope (SEM), IR measurements and vibrating sample magnetometer (VSM). XRD patterns clearly showed the formation of zinc ferrite. The particle size was observed to increase from 19 to 35 nm with increasing annealing temperature. The lattice constants were observed to decrease with increasing particle size. The nanoparticles size were confirmed using SEM measurements. IR measurements were carried to confirm the phase formation of ZnFe2O4 nanoparticles. The Infrared spectra showed the characteristic features of vibrational bands corresponding to spinel ferrite. Room temperature ferromagnetic properties were observed for zinc ferrite having particle sizes 19 and 21 nm. For the particle size 29 and 35 nm it showed paramagnetic nature. The magnetic properties of zinc ferrite nanoparticles were observed to be dependent on the particle size.Keywords: Nanoferrites Zn ferrite Structural properties Magnetic propertie