Topics in access, storage, and sensor networks

In the first part of this dissertation, Data Over Cable Service Interface Specification (DOCSIS) and IEEE 802.3ah Ethernet Passive Optical Network (ETON), two access networking standards, are studied. We study the impact of two parameters of the DOCSIS protocol and derive the probability of message collision in the 802.3ah device discovery scheme. We survey existing bandwidth allocation schemes for EPONs, derive the average grant size in one such scheme, and study the performance of the shortest-job-first heuristic. In the second part of this dissertation, we study networks of mobile sensors. We make progress towards an architecture for disconnected collections of mobile sensors. We propose a new design abstraction called tours which facilitates the combination of mobility and communication into a single design primitive and enables the system of sensors to reorganize into desirable topologies alter failures. We also initiate a study of computation in mobile sensor networks. We study the relationship between two distributed computational models of mobile sensor networks: population protocols and self-similar functions. We define the notion of a self-similar predicate and show when it is computable by a population protocol. Transition graphs of population protocols lead its to the consideration of graph powers. We consider the direct product of graphs and its new variant which we call the lexicographic direct product (or the clique product). We show that invariants concerning transposable walks in direct graph powers and transposable independent sets in graph families generated by the lexicographic direct product are uncomputable. The last part of this dissertation makes contributions to the area of storage systems. We propose a sequential access detect ion and prefetching scheme and a dynamic cache sizing scheme for large storage systems. We evaluate the cache sizing scheme theoretically and through simulations. We compute the expected hit ratio of our and competing schemes and bound the expected size of our dynamic cache sufficient to obtain an optimal hit ratio. We also develop a stand-alone simulator for studying our proposed scheme and integrate it with an empirically validated disk simulator

Synthesis, Characterization and Quantification of Simvastatin Metabolites and Impurities

Simvastatin is used in treatment of hypercholesterolemia because it regulates cholesterol synthesis as a result of its β-hydroxy acid acting as an inhibitor of 3-hydroxy-methylglutaryl coenzyme A (HMG-CoA). The present communication deals with synthesis, characterization and development of accurate, precise and sensitive Reverse Phase High Performance Liquid Chromatography (RP-HPLC) method for simultaneous estimation of simvastatin and its synthetic impurities. The impurities methyl ether and β-hydroxy acid of simvastatin were synthesized in the laboratory and characterized by MS, NMR and FT-IR spectroscopy. The separation of simvastatin and its impurities was carried out on an isocratic JASCO RP-HPLC system using KYA TECH HIQ SIL C18 column (150 × 4.6 mm internal diameter, particle size 5 μm) operating at ambient temperature using acetonitrile:water (80:20 v/v) with 0.1% orthophosphoric acid as mobile phase. The method developed for HPLC analysis of three impurities along with simvastatin was validated using ICH Q2B (R1) guidelines and it complied with these guidelines. The results of analysis were found to be in the range of 98.14% to 101.89% for all analytes with acceptable accuracy and precision. The method can be used for detection and quantification of synthetic impurities in bulk or formulations of simvastatin

Novel Spectrophotometric Method for Estimation of Olmesartan Medoxomil from its Tablet Dosage Form Using Hydrotropic Solubilization

Aim: Quantitative estimation of poorly water-soluble drugs involves use of organic solvents. In the present investigation, hydrotropic solubilization is employed to enhance the aqueous solubilities of poorly water-soluble drugs like Olmesartan Medoxomil in tablet dosage forms. Material and methods: This method utilizes 0.05 M Sodium acetate solution as hydrotropic solubilizing agent Where Olmesartan Medoxomil shows maximum absorbance at 256 nm. The 0.05 M Sodium acetate solution does not show any interference with the sampling wavelength. The hydrotropic agent and additives used in the manufacture of tablets did not interfere in the analysis. Results and Conclusion: The drug obeys the Beer’s Law in the concentration range 2-14 μg/ml with correlation coefficient value of 0.9987. The developed reliable method was validated statistically following ICH Q2B (R1) guidelines. Statistical analysis proved that the method was simple and rapid for the estimation of Olmesartan Medoxomil and can be used for routine analysis of Olmesartan Medoxomil in quality control laboratories. The ex vivo mucoadhesion time of patches ranged between 109 min (FA10) to 126 min (FB14). The ex vivo mucoadhesive force was in the range of 0.278 to 0.479 Kg.m.s-2. The in vitro drug release studies revealed that formulation FA8 released 84% and FB16 released 99.01% of drug in 140 min.Objetivo: La estimación cuantitativa de fármacos poco solubles en agua implica el uso de disolventes orgánicos. En la presente investigación, se emplea la solubilización hidrotrópica para mejorar las solubilidades acuosas fármacos poco solubles en agua como el olmesartán medoxomilo dosificado en comprimido. Material y Métodos: Este método emplea acetato sódico 0,05 M como agente solubilizante hidrotrópico, mostrando el olmesartán medoxomilo una absorbancia máxima a 256 nm. La solución de acetato 0.05 M no muestra ninguna interferencia con la longitud de onda de muestreo. El agente hidrotrópico y los aditivos utilizados en la elaboración de los comprimidos no interfieren en el análisis. Resultados y conclusiones: El fármaco obedece a la Ley de Beer en el intervalo de concentraciones 2-14 mg / ml con un de coeficiente de correlación de 0,9987. El método desarrollado fue validado estadísticamente siguiendo las directrices ICH Q2B (R1) . El análisis estadístico demostró que el método era sencillo y rápido para la estimación de olmesartán medoxomilo y se puede utilizar para análisis de rutina de olmesartán medoxomilo en laboratorios de control de calidad

HPLC ANALYSIS OF HUMAN URINE FOR OXALATE CONTENT

Objective: In the present communication, development and validation of reverse phase-high performance liquid chromatography method have been carried out for estimation of oxalate content in the urine of human volunteers with recurrent kidney stone disease and healthy status.Methods: The analysis of oxalic acid has been carried out on KYA TECH HiQ Sil C18HS column using a mobile phase of methanol: 0.001 N acetic acid in water (50:50, v/v) with a flow rate of 1 ml/min and detection wavelength, 237 nm.Results: Analysis of oxalate content was carried out using single point calibration method with retention at 2.705 min with good resolution parameters. Urine sample collected from kidney stone patients and healthy volunteers over the period of 24 h were analyzed and it has been found that concentration of oxalate in healthy volunteers is less than 12 µg/ml whereas that in case of kidney stone patients is in the range of 39-151 µg/ml and this data can be utilized for further interpretations about oxalate content in healthy and kidney stone diseased volunteers. This method was validated as per united states food and drug administration (USFDA) guidelines by the study of accuracy, precision, linearity, range, selectivity, the lower limit of quantitation, extraction recovery studies and stability studies for determining oxalate content in the urine of human volunteers. As relative standard deviations of oxalate content estimated are less than 5 percent, the method can be claimed accurate, precise, sensitive and selective for determining oxalate content in the urine of human volunteers.Conclusion: The results are satisfactory, proving the effectiveness of the method for analysis of oxalate content from other biological fluids with few optimizations

Synthetic Biology Open Language Visual (SBOL Visual), version 1.0.0

In this BioBricks Foundation Request for Comments (BBF RFC), we specify the Synthetic Biology Open Language Visual standard (SBOL Visual) to enable consistent, human-readable depiction of genetic designs

Synthetic Biology Open Language Visual (SBOL Visual) Version 2.1

People who are engineering biological organisms often find it useful to communicate in diagrams, both about the structure of the nucleic acid sequences that they are engineering and about the functional relationships between sequence features and other molecular species . Some typical practices and conventions have begun to emerge for such diagrams. The Synthetic Biology Open Language Visual (SBOL Visual) has been developed as a standard for organizing and systematizing such conventions in order to produce a coherent language for expressing the structure and function of genetic designs. This document details version 2.1 of SBOL Visual, which builds on the prior SBOL Visual 2.0 standard by expanding diagram syntax to include methods for showing modular structure and mappings between elements of a system, interactions arrows that can split or join (with the glyph at the split or join indicating either superposition or a chemical process), and adding new glyphs for indicating genomic context (e.g., integration into a plasmid or genome) and for stop codons

Database of epidemic trends and control measures during the first wave of COVID-19 in mainland China.

OBJECTIVES: In this data collation study, we aimed to provide a comprehensive database describing the epidemic trends and responses during the first wave of coronavirus disease 2019 (COVID-19) throughout the main provinces in China. METHODS: From mid-January to March 2020, we extracted publicly available data regarding the spread and control of COVID-19 from 31 provincial health authorities and major media outlets in mainland China. Based on these data, we conducted descriptive analyses of the epidemic in the six most-affected provinces. RESULTS: School closures, travel restrictions, community-level lockdown, and contact tracing were introduced concurrently around late January but subsequent epidemic trends differed among provinces. Compared with Hubei, the other five most-affected provinces reported a lower crude case fatality ratio and proportion of critical and severe hospitalised cases. From March 2020, as the local transmission of COVID-19 declined, switching the focus of measures to the testing and quarantine of inbound travellers may have helped to sustain the control of the epidemic. CONCLUSIONS: Aggregated indicators of case notifications and severity distributions are essential for monitoring an epidemic. A publicly available database containing these indicators and information regarding control measures is a useful resource for further research and policy planning in response to the COVID-19 epidemic

Performance of the IEEE 802.3 EPON Registration Scheme Under High Load

The proposed standard for the IEEE 802.3 Ethernet Passive Optical Network includes a random delayed transmission scheme for registration of new nodes. Although the scheme performs well on low loads, our simulation demonstrates the degraded and undesirable performance of the scheme at higher loads. We propose a simple modification to the current scheme that increases its range of operation and is compatible with the IEEE draft standard. We demonstrate the improvement in performance gained without any significant increase in registration delay