159 research outputs found
Correction to: Short- and long-term outcomes in infective endocarditis patients: a systematic review and meta-analysis
No full textCorrection Unfortunately, after publication of this article [1], it was noticed that the name of the fifth author was incorrectly displayed as Akshaya Srikanth Bahagavathula. The correct name is Akshaya Srikanth Bhagavathula and can be seen in the corrected author list above. The original article has also been updated to correct this error
ODDS Oregon needs assessment (ONA) third party analysis review report
Get PDFprepared for: Oregon Department of Human Services, Office of Developmental Disabilities Services ; prepared by: University Center for Excellence in Developmental Disabilities, Biostatistics and Design Program at Oregon Health & Science University ; authors: Willi Horner-Johnson, Ph.D., Priya Srikanth, M.P.H., Alison J. Martin, Ph.D., Rhonda Eppelsheimer, M.S.W.This archived document is maintained by the State Library of Oregon as part of the Oregon Documents Depository Program. It is for informational purposes and may not be suitable for legal purposes.Includes bibliographical references.Mode of access: Internet from the Oregon Government Publications Collection.Text in English
Better outcomes for hospitalized patients with TIA when in stroke units: An observational study, Author Response (Editorial)
No full textEditors' Note: Drs. Phan and Srikanth point out that in “Better outcomes for hospitalized patients with TIA when in stroke units: An observational study,” the recurrence rate was much higher than that in an Australian rapid/outpatient-based TIA pathway. Inability to walk (which could indicate stroke instead of TIA), low usage of antiplatelet therapy, and time to antiplatelet therapy are possible explanations. In response, Cadilhac et al. comment that initiation of aspirin within several hours vs 24–48 hours has not been shown to clearly improve outcomes.No Full Tex
Topological analysis of the grain boundary space
No full textThesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2011.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from PDF version of thesis.Includes bibliographical references (p. 117-125).Grain boundaries and their networks have a profound influence on the functional and structural properties of every class of polycrystalline materials and play a critical role in structural evolution and phase transformations. Recent experimental advances enable a full crystallographic characterization, including the boundary misorientation and inclination parameters, of grain boundaries. Despite these advances, a lack of appropriate analytical tools severely undermines our ability to analyze and exploit the full potential of the vast amounts of experimental data available to materials scientists. This is because the topology of the grain boundary space is unknown and even a well-studied part of the complete grain boundary space, the misorientation space, is relatively poorly understood. This thesis summarizes efforts to improve the representation of misorientation information and to understand the topology of the complete grain boundary space. First, the topology of the space of misorientations is discussed with a focus on the effect of symmetries on the minimum embedding dimensions in Euclidean space. This opens the door to a new method of representation of misorientation information in which grain boundaries can be uniquely colored by their misorientations. Second, conditions under which the topology of the grain boundary space has been resolved are presented. Resolving the topology of the complete grain boundary space not only facilitates statistical analysis of grain boundaries, but can also help describe the structure-property relationships of these interfaces.by Srikanth Patala.Ph.D
Design and Implementation of Distributed Space-Frequency to Achieve Cooperative Diversity in Wireless Relay Networks
Get PDFRecently, there has been much interest in modulation techniques that can help in achieving transmit diversity motivated by the increased capacity of multiple-input multiple- output (MIMO) channel. To achieve transmit diversity the transmitter needs to be equipped with multiple antennas. The antennas should be well separated to have uncorrelated fading among the different antennas. This results in higher diversity orders and higher coding gains. However, achieving transmit diversity for mobile units requires cooperative diversity. In this context, the space-time codes (STC) for spread spectrum CDMA systems have received great interest in recent times. The schemes presented in this paper ensure that the limitations of conventional correlation receivers are overcome. The effect of the space-time code distribution on the space-time code that achieves full diversity with maximum coding gain over MIMO channels is studied in this paper. In most of the analogous works surveyed so far, it is observed, that, there has been very little focus on the study of systems that exhibit diversity of all the three forms namely: source coding diversity, channel coding diversity and user cooperation diversity. However, in this paper, all these three forms of diversity are uniformly considered and the proposed schemes are studied for their robustness and performance. It is shown, that, the proposed space-time coded communication scheme is both bandwidth and power efficient. To analyze the proposed scheme fully, communication over fading channels is considered. The maximum-likelihood decision metric is used to decode the original information in the presence of channel estimation errors. A study of the performance of the proposed STC system in the presence of slowly changing Rayleigh channels is also presented. Keywords: Multipath fading, Communication systems, Distributed Space-time codes, Wireless relay networks, Signal Processing, Multinode Cooperative communication, multiple sensor detection system
Study of structural integrity of interstellar spacecraft reaction chamber and thrust structure in support of Project Icarus
No full textThis thesis supports studies of the international effort of Project Icarus, dedicated to the unmanned, interstellar exploration of nearby stellar systems within the next century. The target system is 5.9 light years away, with a required velocity of 12% the speed of light. This study primarily focuses on the structural analysis of the reaction chamber and supporting structure of the Icarus interstellar spacecraft, which will be powered by nuclear fusion reactions to achieve the required velocity and time-frame for the mission. First, a computational finite element analysis is conducted on the reaction chamber in terms of loading, vibration, and fatigue. Different configurations and assumptions are studied for the reaction chamber as well. Present-day manufacturing considerations are also taken into account, with a modest extrapolation for future manufacturing technologies that are currently not in existence. Next, the thrust supporting structure for the reaction chamber is incorporated into the analysis. This study serves as a precursor for the multi-level analysis into the eventual detailed design and production of an interstellar spacecraft, and is the first such study.M.S.Includes bibliographical referencesby Srikanth K. Redd
Three essays on the equity and adequacy of K-12 school funding for English language learners: a national analysis
No full textThis dissertation follows a three publishable papers format to analyze school funding equity and adequacy for English Language Learners [ELLs]. In the first paper, I provide background on the legal rights of ELLs and compare the criteria for each state for identifying, assessing, and exiting ELLs. I then describe funding policies within each state for providing for the educational needs of ELLs. ELLs are a legally protected class of students under the Civil Rights Act of 1964 and the Equal Educational Opportunities Act of 1974 (Jimenez-Castellanos & Topper, 2012). However, outcome gaps between ELLs and non-ELLs have continued to persist. States vary widely in their policies for ELLs, including in how they identify, reclassify, and fund programs for them. I find that the majority of states use a single test score to identify and reclassify ELLs and that more than 70% of states use tests from the World Class Instructional Design and Assessment [WIDA] consortium. Concerning funding, I estimate an average per pupil yield of only 8,500 per pupil for ELLs. The inadequate funding per pupil is likely driven by inadequate estimates of both base funding per pupil and pupil weights. I conclude with suggestions for further research. In the second paper, I use district-level data from the School Finance Indicators Database [SFID] to analyze the equity of school funding for ELLs across the nation (Baker, Di Carlo, Srikanth & Weber, 2021). That is, I attempt to determine whether states actually provide greater funding and resources per pupil to districts serving higher ELL concentrations. I use three different measures of school funding equity- the ratio of state and local revenues per pupil relative to other districts in the same labor market, the ratio of operating expenditures per pupil relative to other districts in the same labor market, and the number of teachers per 100 pupils. Overall, I find no statistically significant relationship between relative revenue and ELL concentration, and a statistically significant but weak relationship between relative expenditures and ELL concentration and teachers per 100 pupils and ELL concentration. I also analyze school funding equity across the three measures for all 50 states. Only seven states have positive and statistically significant results across all three resource measures- Alaska, Kentucky, Maine, Maryland, Missouri, Montana, and North Dakota. I conclude with recommendations for legislators, advocates, and administrators to improve the equity of school funding for ELLs. Finally, in the third paper I attempt to determine the adequacy of school funding for districts serving higher ELL concentrations. I use data from the School Finance Indicators Database (Baker, Di Carlo, Srikanth and Weber, 2021) and the Stanford Education Data Archive (Reardon, Ho, Shear, Fahle, Kalogrides, Jang & Chavez, 2021) to determine the costs for ELLs to meet national average scores in standardized tests of English Language Arts and math. Using a National Education Cost Model, I find that a 10% increase in ELL concentration is associated with additional required spending between approximately 1,600 to 8 billion and $10 billion for an increase of 10% in ELL concentration. I conclude with recommendations for policymakers and administrators to improve the adequacy of school funding for ELLs and recommendations for further research.Ph.D.Includes bibliographical reference
Development of a Computational Framework for Aeroelasticity of Geometrically Nonlinear Structures: A Partitioned Coupling Approach
No full textHigh Altitude Long Endurance (HALE) configurations have gained much popularity in the recent past. Although, HALE aircraft enable efficient and environmental-friendly flying, they necessitate a large Aspect-Ratio wing. These slender structures are prone to large, non-linear deformations which further increase the unsteady nature of aerodynamic flow that can detrimentally impact the structure. In the light of this trend towards an efficient aviation industry of tomorrow, Airbus Innovations UK has ventured into the development of a folding wing tip concept whose benefits are two-fold. First, is the ability to increase span during flight, thereby reducing the induced drag. The folding capability also ensures entry gate requirements at airports. Secondly, the folding mechanism presents load alleviation capabilities with appropriate hinge setup. Alleviation of loads on lifting surfaces directly translates to reduction of the Wing Root Bending Moment (WRBM), which means a reduction of weight. Thus, a further improvement in efficiency of flight. In this work, a nonlinear aeroelastic solver is developed. The proposed partitioned framework couples the industry standard commercial software package MSC Nastran, a structural solver to the Unsteady Vortex Lattice Method (UVLM), an aerodynamic solver. The UVLM module developed, exhibits both static and dynamic capabilities. Three wake models are incorporated. Horse-shoe wake is employed for static simulations and convective wake procedures are available for transient dynamic simulations. The independent modular solvers are coupled using Radial Basis Functions (RBFs) and Nearest Neighbour (NN) approaches. This framework enables the solver to capture the combined effects of structural nonlinearities and unsteady flows. The proposed solver is then verified and validated for two different test cases: NASA CRM Wing and Pazy Wing. Experimental validation is carried out using existing results from related work. The solver is then used to evaluate the “AlbatrossOne”, a hinged wingtips concept by Airbus Innovations UK. Both static and dynamic responses are analysed for load alleviation capabilities.Aerospace Engineerin
Enhanced electrocaloric, pyroelectric and energy storage performance of BaCe Ti1−O3 ceramics
No full textImprovement of Power Quality using Fuzzy Logic Controller In Grid Connected Photovoltaic Cell Using UPQC
Get PDFIn this paper, the design of combined operation of UPQC and PV-ARRAY is designed. The proposed system is composed of series and shunt inverters connected back to back by a dc-link to which pv-array is connected. This system is able to compensate voltage and current related problems both in inter-connected mode and islanding mode by injecting active power to grid. The fundamental aspect is that the power electronic devices (PE) and sensitive equipments (SE) are normally designed to work in non-polluted power system, so they would suffer from malfunctions when supply voltage is not pure sinusoidal. Thus this proposed operating strategy with flexible operation mode improves the power quality of the grid system combining photovoltaic array with a control of unified power quality conditioner. Pulse Width Modulation (PWM) is used in both three phase four leg inverters. A Proportional Integral (PI) and Fuzzy Logic Controllers are used for power quality improvement by reducing the distortions in the output power. The simulated results were compared among the two controller’s strategies With pi controller and fuzzy logic controller.DOI: http://dx.doi.org/10.11591/ijpeds.v5i1.618
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