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2009

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Articles 6781 - 6810 of 7616

Full-Text Articles in Physical Sciences and Mathematics

Synthesis And Physical Studies Of Polycarbonate Of P-Tert-}Butylcalix[4]Arene: A Highly Selective Receptor For Na^+, Muhammad Ashram, Nawash Al Ghezawi, Ibrahim Abu Awaad, Gülsen Asman Jan 2009

Synthesis And Physical Studies Of Polycarbonate Of P-Tert-}Butylcalix[4]Arene: A Highly Selective Receptor For Na^+, Muhammad Ashram, Nawash Al Ghezawi, Ibrahim Abu Awaad, Gülsen Asman

Turkish Journal of Chemistry

The synthesis and characterization of a polycarbonate of p-tert-butylcalix[4]arene 4 are reported. It was synthesized by condensation of p-tert-butylcalix[4]arenetetraol derivative 3 with ethyl chloroformate. This new polymer possesses a hydrolyzable backbone and tunable hydrophobic/hydrophilic properties. The experimental results indicate that the polycarbonate was successfully synthesized with average molecular weight \overline{M}_{w}, (2.328 \times 10^4 g/mol), which was determined by static light scattering method using a Berry plot. The structure of this polymer was determined by IR spectroscopy. The thermal properties were investigated using differential scanning calorimetry (DSC). The degree of crystallinity was measured by means of XRD. The extraction ability of …

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Determination Of Trace Borohydride In Basic Solutions Using Differential Pulse Polarography, Ülkü Ünal, Güler Somer Jan 2009

Determination Of Trace Borohydride In Basic Solutions Using Differential Pulse Polarography, Ülkü Ünal, Güler Somer

Turkish Journal of Chemistry

Synthesis of borohydride is important because of its use as a hydrogen energy source. The objective of this study was to develop a new and simple method for the trace determination of borohydride so that it can be used during the investigation of a new reaction for its synthesis or in some kinetic studies. A differential pulse polarographic method has been developed for this purpose since the results obtained with this method are very reproducible and the instrument used is not expensive. The optimum working condition was found to be as 0.05 M phosphate buffer (pH 9), containing 0.1 M …

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Secondary Metabolites From Nepeta Heliotropifolia, Zühal Güvenalp, Hi̇lal Özbek, Ayşe Kuruüzüm-Uz, Cavi̇t Kazaz, L. Ömür Demi̇rezer Jan 2009

Secondary Metabolites From Nepeta Heliotropifolia, Zühal Güvenalp, Hi̇lal Özbek, Ayşe Kuruüzüm-Uz, Cavi̇t Kazaz, L. Ömür Demi̇rezer

Turkish Journal of Chemistry

Two iridoid glycosides, ixoroside (1) and nepetanudoside B (2); 1 phenylpropanoid glycoside, coniferine (3); 2 flavone glycosides, apigenin 7-O-glucuronide (4) and apigenin 7-O-glucopyranoside (5); 2 triterpenes, oleanolic acid (6) and ursolic acid (7); and 1 sterol, \beta-sitosterol (8), were isolated from the aerial parts of Nepeta heliotropifolia Lam. (Lamiaceae). Their structures were identified by means of spectroscopic methods (1D- and 2D-NMR, UV, and EIMS).

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Antioxidant Galloylated Flavonoids From Geranium Tuberosum L. Subsp. Tuberosum, Di̇dem Şöhretoğlu, Mahmut Koray Sakar, Suna Atasayar Sabuncuoğlu, Hi̇lal Özgüneş, Olov Sterner Jan 2009

Antioxidant Galloylated Flavonoids From Geranium Tuberosum L. Subsp. Tuberosum, Di̇dem Şöhretoğlu, Mahmut Koray Sakar, Suna Atasayar Sabuncuoğlu, Hi̇lal Özgüneş, Olov Sterner

Turkish Journal of Chemistry

Phytochemical investigations on the most active EtOAc extract led to the isolation of 9 flavonoids [quercetin (1), quercetin 3-O-\beta-glucopyranoside (2), quercetin 3-O-\beta-galactopyranoside (3), quercetin 3-O-(2''-O-galloyl)-\beta-glucopyranoside (4), quercetin 3-O-(2''-O-galloyl)-\beta-galactopyranoside (5), quercetin 3-O-(6''-O-galloyl)-\beta-glucopyranoside (6), quercetin 3-O-(6''-O-galloyl)-\beta-galactopyranoside (7), quercetin-3-O-\alpha -arabinofuranoside (8), and quercetin-3-O-\alpha-rhamnopyranosyl-(1\to 6)-\beta-glucopyranoside (9)] and a simple phenolic compound (methyl gallate) (10). The structures of the compounds were elucidated by 1- and 2-dimensional NMR techniques (^1H, ^{13}C, COSY, HMBC, and HMQC) and ESI-TOF-MS spectrometry. H_2O_2-induced lipid peroxidation inhibitor effects in human red blood cells of different extracts of G. tuberosum L. subsp. tuberosum aerial parts were also investigated. All the compounds tested …

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A Simple Spectrophotometric Method For The Determination Of Iron(Ii) Aqueous Solutions, M. Jamaluddin Ahmed, Uttam Kumer Roy Jan 2009

A Simple Spectrophotometric Method For The Determination Of Iron(Ii) Aqueous Solutions, M. Jamaluddin Ahmed, Uttam Kumer Roy

Turkish Journal of Chemistry

An ultra-sensitive and highly selective non-extractive spectrophotometric method is presented for the rapid determination of iron(II) at trace levels using 2', 3, 4', 5, 7-Pentahydroxyflavone (morin) as a new spectrophotometric reagent in slightly acidic solution (0.0001-0.0002 M H_2SO_4). The reaction is instantaneous and absorbance remains stable for over 24 h (\lambda_{max} = 415 nm). The molar absorptivity was found to be 6.85 \times 10^4 L mol^{-1} cm^{-1}. Linear calibration graphs were obtained for 0.01-10 \mu g mL^{-1} of Fe^{II}. The stoichiometric composition of the chelate is 1:2 (Fe:morin). Large excesses of over 50 cations, anions, and complexing agents (e.g., tartrate, …

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A Study Of Growth And Breakdown Of Passive Film On Copper Surface By Electrochemical Impedance Spectroscopy, Amtul Naseer, Athar Yaseen Khan Jan 2009

A Study Of Growth And Breakdown Of Passive Film On Copper Surface By Electrochemical Impedance Spectroscopy, Amtul Naseer, Athar Yaseen Khan

Turkish Journal of Chemistry

Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry were used to investigate the oxide layer formed on a copper disc electrode and the changes that took place when treated potentiostatically in the range of -0.3 V to 0.9 V in aqueous buffer solution of pH 9.2. Equivalent circuits were used to model the response of the electrode, initially at equilibrium to an applied potential. These circuits were proposed for different potential ranges in order to illustrate the Cu/oxide/electrolyte system and its properties in terms of 2 interfaces. A criterion for the applicability of equivalent circuit models was discussed. Changes in the …

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A Simple And Efficient One-Pot Multicomponent Synthesis Of \Beta-Acetamido Carbonyl Compounds With Zn(Hso_4)_2 And Co(Hso_4)_2 As Catalysts, Ahmad Reza Momeni, Maryam Sadeghi, Motahareh Hadizadeh Jan 2009

A Simple And Efficient One-Pot Multicomponent Synthesis Of \Beta-Acetamido Carbonyl Compounds With Zn(Hso_4)_2 And Co(Hso_4)_2 As Catalysts, Ahmad Reza Momeni, Maryam Sadeghi, Motahareh Hadizadeh

Turkish Journal of Chemistry

Zn(HSO_4)_2 and Co(HSO_4)_2 has been used as efficient catalysts for the preparation of \beta-acetamido carbonyl compounds by Dakin-West reaction.

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Electrochemical And Optical Properties Of An Azo Dye Based Conducting Copolymer, Ati̇lla Ci̇haner, Fati̇h Algi Jan 2009

Electrochemical And Optical Properties Of An Azo Dye Based Conducting Copolymer, Ati̇lla Ci̇haner, Fati̇h Algi

Turkish Journal of Chemistry

The electrochemical and optical properties of a novel conducting copolymer called poly(2,5'-dimethyl-[4-(2,5-di-thiophen- 2-yl-pyrrol-1-yl)-phenyl]azobenzene-co-(3,4-ethylenedioxythiophene)) (poly(1-co-EDOT)) are reported. Electrochemically synthesized poly(1-co-EDOT) based on the azo dye has a well-defined and reversible redox couple (0.37 V vs. Ag/AgCl) with good cycle stability. The copolymer film exhibits high conductivity (13 S/cm) as well as electrochromic behavior (magenta when neutralized and transmissive sky blue when oxidized). Furthermore, electro-optically active copolymer film has a low band gap of 1.79 eV with a \pi-\pi* transition at 555 nm.

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An Efficient One Pot Synthesis Of 1,4-Dihydropyridines Using Alumina Sulfuric Acid (Asa) Catalyst, Mustafa Arslan, Cüneyt Faydali, Mustafa Zengi̇n, Mustafa Küçüki̇slamoğlu, Hülya Demi̇rhan Jan 2009

An Efficient One Pot Synthesis Of 1,4-Dihydropyridines Using Alumina Sulfuric Acid (Asa) Catalyst, Mustafa Arslan, Cüneyt Faydali, Mustafa Zengi̇n, Mustafa Küçüki̇slamoğlu, Hülya Demi̇rhan

Turkish Journal of Chemistry

An efficient synthetic method for 1,4-dihydropyridines has been developed using 3 or 4 component condensation reactions of aldehydes, 1,3-dicarbonyl compounds, and ammonium acetate in the presence of alumina sulfuric acid catalyst in minimum methanol at reflux temperature. This procedure offers several advantages including high yields, an environmentally friendly procedure, short reaction times, and a simple work-up procedure.

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Synthesis, Characterization, And Antibacterial Activity Of Some Transition Metals With The Schiff Base N-(2-Furanylmethylene)-3-Aminodibenzofuran, Aurora Reiss, Stelian Florea, Theodor Caproiu, Nicolae Stanica Jan 2009

Synthesis, Characterization, And Antibacterial Activity Of Some Transition Metals With The Schiff Base N-(2-Furanylmethylene)-3-Aminodibenzofuran, Aurora Reiss, Stelian Florea, Theodor Caproiu, Nicolae Stanica

Turkish Journal of Chemistry

This paper presents the structure and antibacterial properties of some complexes of Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Hg(II) with a new Schiff base N-(2-furanylmethylene)-3- aminodibenzofuran. The structure of each complex was characterized by spectroscopic methods (IR, UV-Vis, ^1H-NMR, and ESR), conductometric and magnetic data, and thermogravimetric and elementary analysis. According to these data, we propose an octahedral geometry for Co(II), Ni(II), and Cu(II) complexes, and a tetrahedral geometry for Zn(II), Cd(II), and Hg(II) complexes. Antibacterial activity of the ligand and its complexes was tested against selected bacteria. The ligand and all the complexes possess antimicrobial activity, and antimicrobial activity …

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Preparation And Characterization Of Magnetic Chitosan Nanospheres, Doina Hritcu, Marcel I. Popa, Nuculina Popa, Vasile Badescu, Vera Balan Jan 2009

Preparation And Characterization Of Magnetic Chitosan Nanospheres, Doina Hritcu, Marcel I. Popa, Nuculina Popa, Vasile Badescu, Vera Balan

Turkish Journal of Chemistry

A method for the preparation of magnetite/chitosan composite nanoparticles was developed. Colloidal magnetite particles (Fe_3O_4 produced by co-precipitation and stabilized in suspension by adding a non-ionic surfactant (Pluronic F127) were subsequently covered with a layer of chitosan (CS) prepared by ionotropic gelation using sodium tripolyphosphate (STPP) as a crosslinking agent. The products were characterized in terms of the following parameters: size distribution and \zeta-potential (by laser diffraction analysis), surface morphology (TEM), composition (FTIR, elemental analysis), magnetic properties (magnetic susceptibility analysis), and concentration of surface functional groups (potentiometric titration). The synthesis parameters were optimized for obtaining uniformly distributed colloidally stable, biocompatible …

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Three-Component Process For The Synthesis Of Some Pyrrole Derivatives Under Microwave Irradiation, Farhad Hatamjafari, Nasser Montazeri Jan 2009

Three-Component Process For The Synthesis Of Some Pyrrole Derivatives Under Microwave Irradiation, Farhad Hatamjafari, Nasser Montazeri

Turkish Journal of Chemistry

We report a short and efficient 3-component reaction for synthesis of a series of [1,2-b]pyrrole derivatives from ninhydrin, alkyl propiolates, and simple primary amines under solvent free and microwave irradiation. This method provides a new route to produce pyrrole derivatives in good to excellent yields.

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4h-Pyran-4-One Derivatives:; Leading Molecule For Preparation Of Compounds With Antimycobacterial Potential, Demet Us, Ece Gürdal, Barkin Berk, Si̇nem Öktem, Tanil Kocagöz, Berrak Çağlayan, Işil Aksan Kurnaz, Di̇lek Demi̇r Erol Jan 2009

4h-Pyran-4-One Derivatives:; Leading Molecule For Preparation Of Compounds With Antimycobacterial Potential, Demet Us, Ece Gürdal, Barkin Berk, Si̇nem Öktem, Tanil Kocagöz, Berrak Çağlayan, Işil Aksan Kurnaz, Di̇lek Demi̇r Erol

Turkish Journal of Chemistry

A series of 3-hydroxy-6-methyl-2-((4-substitutedpiperazin-1- yl)methyl)-4H-pyran-4-one structured compounds were synthesized by reacting 5-hydroxy-2-methyl-4H-pyran-4-one with suitable piperazine derivatives using Mannich reaction conditions. Antibacterial activities of the compounds for E. coli, S. paratyphi, S. flexneri, E. gergoviae, and M. smegmatis were assessed in vitro by using broth dilution for determination of the minimum inhibitory concentration (MIC). In addition, their inhibitory effects over DNA gyrase enzyme were evaluated using a DNA gyrase supercoiling assay. Among the synthesized compounds; compound 7 showed a 4 \mu g/mL MIC value for M. smegmatis, whereas the other compounds demonstrated moderate to high activity. Those tested in the supercoiling …

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Antioxidant And Anticholinesterase Constituents Of Salvia Poculata, Ufuk Kolak, Işil Hacibeki̇roğlu, Mehmet Öztürk, Fevzi̇ Özgökçe, Gülaçti Topçu, Ayhan Ulubelen Jan 2009

Antioxidant And Anticholinesterase Constituents Of Salvia Poculata, Ufuk Kolak, Işil Hacibeki̇roğlu, Mehmet Öztürk, Fevzi̇ Özgökçe, Gülaçti Topçu, Ayhan Ulubelen

Turkish Journal of Chemistry

Two triterpenoids, namely 2\alpha,3\alpha-dihydroxy-24-nor- 4(23),12-oleanadien-28-oic acid (1) and ursolic acid (2); 4 flavonoids, namely 5-hydroxy-7,4'-dimethoxyflavone (3), cirsimaritin (4), eupatilin (5), and salvigenin (6); a diterpenoid, namely sclareol (7); and a steroid, namely \beta-sitosterol (8), were isolated from the aerial parts of Salvia poculata Nab., a Turkish endemic Salvia species. Total phenolic and flavonoid contents of the crude extract were determined as pyrocatechol and quercetin equivalents, respectively. The antioxidant activity of the crude extract and the isolated compounds (2-8) was established using \beta-carotene bleaching, superoxide anion radical, and ABTS cation radical scavenging activity. In addition, the anticholinesterase activity of the crude …

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Partial Regeneration Of Ni-Based Catalysts For Hydrogen Production Via Methane Cracking Part Ii: Modeling And Optimization, Reyyan Koç, Erdoğan Alper, Eric Croiset, Ali Elkamel Jan 2009

Partial Regeneration Of Ni-Based Catalysts For Hydrogen Production Via Methane Cracking Part Ii: Modeling And Optimization, Reyyan Koç, Erdoğan Alper, Eric Croiset, Ali Elkamel

Turkish Journal of Chemistry

High purity, carbon monoxide-free hydrogen and filamentous carbon can be produced by thermo-catalytic cracking of methane. Carbon filaments continue to grow until the catalyst deactivates because of carbon encapsulation. Regeneration of catalyst is important to maintain a continuous process. Our work on optimization of the partial regeneration method showed that activity of the catalyst can be sustained for longer times by gasifying not all but some extent of the deposited carbon. In the previous work, a kinetic model was developed to be able to understand the reaction mechanism of deactivation of fresh catalyst at the molecular level. The objective of …

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Electrospray And Photoionization Mass Spectrometry For The Characterization Of Organic Matter In Natural Waters: A Qualitative Assessment, William C. Hockaday, Jeremiah M. Pucell, Alan G. Marshall, Jeffery A. Baldock, Patrick G. Hatcher Jan 2009

Electrospray And Photoionization Mass Spectrometry For The Characterization Of Organic Matter In Natural Waters: A Qualitative Assessment, William C. Hockaday, Jeremiah M. Pucell, Alan G. Marshall, Jeffery A. Baldock, Patrick G. Hatcher

Chemistry & Biochemistry Faculty Publications

Fourier-transform ion cyclotron resonance mass spectrometry (MS) has demonstrated potential to revolutionize the fields of limnology and chemical oceanography by identifying the individual molecular components of organic matter in natural waters. The use of MS for this purpose is made possible by the electrospray technique which successfully ionizes polar, nonvolatile organic molecules. Another recently developed ion source, atmospheric pressure photoionization (APPI), extends MS capabilities to less polar molecules. This article presents early results on the application of APPI MS to natural organic matter. We compare APPI MS and electrospray MS data for dissolved organic matter from Lake Drummond (Virginia, USA). …

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Photochemical Degradation Of Dissolved Organic Matter And Dissolved Lignin Phenols From The Congo River, Robert G. M. Spencer, Aron Stubbins, Peter J. Hernes, Kenneth Mopper, Anthony K. Aufdenkampe, Rachael Y. Dyda, Vincent L. Mwamba, Arthur M. Mangangu, Jose N. Wabakanghanzi, Johan Six Jan 2009

Photochemical Degradation Of Dissolved Organic Matter And Dissolved Lignin Phenols From The Congo River, Robert G. M. Spencer, Aron Stubbins, Peter J. Hernes, Kenneth Mopper, Anthony K. Aufdenkampe, Rachael Y. Dyda, Vincent L. Mwamba, Arthur M. Mangangu, Jose N. Wabakanghanzi, Johan Six

Chemistry & Biochemistry Faculty Publications

Photochemical degradation of Congo River dissolved organic matter (DOM) was investigated to examine the fate of terrigenous DOM derived from tropical ecosystems. Tropical riverine DOM receives greater exposure to solar radiation, particularly in large river plumes discharging directly into the open ocean. Initial Congo River DOM exhibited dissolved organic carbon (DOC) concentration and compositional characteristics typical of organic rich blackwater systems. During a 57 day irradiation experiment, Congo River DOM was shown to be highly photoreactive with a decrease in DOC, chromophoric DOM (CDOM), lignin phenol concentrations (Σ8) and carbon-normalized yields (Λ8), equivalent to losses of ~45, 85–95, >95 and …

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Multiple Imputation To Correct For Measurement Error In Admixture Estimates In Genetic Structured Association Testing, Miguel A. Padilla, Jamin Divers, Laura K. Vaughan, David B. Allison, Hemant K. Tiwari Jan 2009

Multiple Imputation To Correct For Measurement Error In Admixture Estimates In Genetic Structured Association Testing, Miguel A. Padilla, Jamin Divers, Laura K. Vaughan, David B. Allison, Hemant K. Tiwari

Psychology Faculty Publications

Objectives: Structured association tests ( SAT), like any statistical model, assumes that all variables are measured without error. Measurement error can bias parameter estimates and confound residual variance in linear models. It has been shown that admixture estimates can be contaminated with measurement error causing SAT models to suffer from the same afflictions. Multiple imputation (MI) is presented as a viable tool for correcting measurement error problems in SAT linear models with emphasis on correcting measurement error contaminated admixture estimates. Methods: Several MI methods are presented and compared, via simulation, in terms of controlling Type I error rates for both …

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Versatile Extensible Security System For Mobile Ad Hoc Networks, Jung Chang Jan 2009

Versatile Extensible Security System For Mobile Ad Hoc Networks, Jung Chang

Master's Projects

Mobile Ad hoc Network (MANET) is becoming more and more popular in scientific, government, and general applications, but security system for MANET is still at infant stage. Currently, there are not many security systems that provide extensive security coverage for MANET. Moreover, most of these security systems assume nodes have infinite computation power and energy; an assumption that is not true for many mobiles. Versatile and Extensible System (VESS) is a powerful and versatile general-purpose security suite that comprises of modified versions of existing encryption and authentication schemes. VESS uses a simple and network-efficient but still reliable authentication scheme. The …

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Randomized Greedy Hot-Potato Routing On The Multi-Dimensional Torus, Raymond Y. Chi Jan 2009

Randomized Greedy Hot-Potato Routing On The Multi-Dimensional Torus, Raymond Y. Chi

Master's Projects

We present extensive simulation and analysis on a traditional, simple, efficient dynamic hot potato routing algorithm on a multi-dimensional torus network. These simulations are performed under a more recent network model than previous, more limited studies, with dynamic (rather than batch) models, no flow-control, and extended high dimensional scenarios. We collect more comprehensive statistics on system performance, and empirically show that the system can recover from worst-case scenarios to quickly re-achieve its standard steady-state delivery rates, with expected delivery time for a packet of O(n), where n is the initial packet distance from its destination. Experiments also show that for …

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Intrusion Alerts Analysis Using Attack Graphs And Clustering, Hardik Patel Jan 2009

Intrusion Alerts Analysis Using Attack Graphs And Clustering, Hardik Patel

Master's Projects

Network and information security is very crucial in keeping large information infrastructures safe and secure. Many researchers have been working on different issues to strengthen and measure security of a network. An important problem is to model security in order to apply analysis schemes efficiently to that model. An attack graph is a tool to model security of a network which considers individual vulnerabilities in a global view where individual hosts are interconnected. The analysis of intrusion alert information is very important for security evaluation of the system. Because of the huge number of alerts raised by intrusion detection systems, …

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Triggering Of Just-In-Time Compilation In The Java Virtual Machine, Rouhollah Gougol Jan 2009

Triggering Of Just-In-Time Compilation In The Java Virtual Machine, Rouhollah Gougol

Master's Projects

The Java Virtual Machine (Standard Edition) normally interprets Java byte code but also compiles Java methods that are frequently interpreted and runs them natively. The purpose is to take advantage of native execution without having too much overhead for Just-In-Time compilation. A former SJSU thesis tried to enhance the standard policy by predicting frequently called methods ahead of their actual frequent interpretation. The project also tried to increase the compilation throughput by prioritizing the method compilations, if there is more than one hot method to compile at the same time. The paper claimed significant speedup. In this project, we tried …

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Chinese Wall Security Policy, Varun Gupta Jan 2009

Chinese Wall Security Policy, Varun Gupta

Master's Projects

This project establishes a Chinese wall security policy model in the environment of cloud computing. In 1988 Brewer and Nash proposed a very nice commercial security policy in British financial world. Though the policy was well accepted, but the model was incorrect. A decade later, Dr. Lin provided a model in 2003 that meets Brewer & Nash’s Policy. One of the important components in Cloud computing is data center. In order for any company to store data in the center, a trustable security policy model is a must; Chinese wall security policy model will provide this assurance. The heart of …

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Analysis Of Machine Learning Based Methods For Identifying Microrna Precursors, Steve Ikeoka Jan 2009

Analysis Of Machine Learning Based Methods For Identifying Microrna Precursors, Steve Ikeoka

Master's Projects

MicroRNAs are a type of non-coding RNA that were discovered less than a decade ago but are now known to be incredibly important in regulating gene expression despite their small size. However, due to their small size, and several other limiting factors, experimental procedures have had limited success in discovering new microRNAs. Computational methods are therefore vital to discovering novel microRNAs. Many different approaches have been used to scan genomic sequences for novel microRNAs with varying degrees of success. This work provides an overview of these computational methods, focusing particularly on those methods based on machine learning techniques. The results …

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Wormulator: Simulator For Rapidly Spreading Malware, Jyotsna Krishnaswamy Jan 2009

Wormulator: Simulator For Rapidly Spreading Malware, Jyotsna Krishnaswamy

Master's Projects

This project addresses the need for an application level simulator to simulate Internet-wide phenomenon such as flash worms, botnets, Distributed Denial-of-Service attacks, etc. There are many network simulators intended for parallel and distributed simulation, but most are designed to simulate low level communication protocols such as TCP/IP. The desire to simulate rapidly spreading malware for research and teaching purposes lead us to explore the Spamulator, which was designed to simulate spam email on an Internet-wide scale. The Spamulator was developed by a team at the University of Calgary. It is a lightweight, application level simulator, which implements limited set of …

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Hybrid Clustering With Application To Web Pages, Ameya Sabnis Jan 2009

Hybrid Clustering With Application To Web Pages, Ameya Sabnis

Master's Projects

This project explains the process of clustering web pages. With the immense increase in the number of web pages available on the internet, it has become difficult to search for web pages. The clustering of web pages will improve the presentation of web pages to the user and saves the time spent on searching web pages. Various clustering techniques have been proposed by various research scientists to cluster the web pages, but all the techniques suggested have some drawbacks. Since there is lot of scope for further improvement in the field of clustering, the system proposed in this report takes …

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Exploratory Study Of The Download Speed Of Leading University Hospitality And Tourism Department Websites Worldwide, Steven Chan, Rosanna Leung, Rob Law, Wen Shi Jan 2009

Exploratory Study Of The Download Speed Of Leading University Hospitality And Tourism Department Websites Worldwide, Steven Chan, Rosanna Leung, Rob Law, Wen Shi

Hospitality Review

Increased broadband penetration (BP) rates around the world have encouraged web designers to include more web content and additional functions on their web sites, thereby enhancing the richness and playfulness of the information. However, it is often very difficult for web surfers who are still using narrowband connections to access such web sites. Many university web sites target international audiences; therefore their download performance should be considered, as it may directly influence the user experience. This exploratory study examined 331 university hospitality and tourism department web sites in 37 countries. The empirical results showed that entry web pages of universities …

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Effective Width And Expansion Energy Of The Interacting Condensed ^{87}Rb Bose Gas With Finite Size Effects, Ahmed Sayed Hassan, A. M. El-Badry Jan 2009

Effective Width And Expansion Energy Of The Interacting Condensed ^{87}Rb Bose Gas With Finite Size Effects, Ahmed Sayed Hassan, A. M. El-Badry

Turkish Journal of Physics

This work is devoted to study the temperature dependence of the effective width and expansion energy on the finite size and interaction effects (repulsive interactions). It is found that the effective size , and expansion energy in the radial direction E_y of a Bose gas follow a characteristic temperature dependence, i.e. , E_y \propto (T/T_0)^4 if T_0 < T and , E_y \propto (T/T_0) if T_0 > T. Our results show that these two parameters increases with the number of atoms, and with increasing repulsive interaction strength at temperature less than the transition temperature, (T < T_o); yet it has little effect at temperatures higher than the transition temperature (T > T_o). The obtained results are compared with the available experimental data for ^{87}Rb directly, full …

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Studies On Physical Properties And Carrier Conversion Of Sno_2:Nd Thin Films, Jochan Joseph, Varghese Mathew, Jacob Mathew, K. E. Abraham Jan 2009

Studies On Physical Properties And Carrier Conversion Of Sno_2:Nd Thin Films, Jochan Joseph, Varghese Mathew, Jacob Mathew, K. E. Abraham

Turkish Journal of Physics

Neodymium (Nd)-doped SnO_2 transparent conducting oxide thin films were prepared by vapour deposition technique under different deposition parameters: substrate temperature, time and flow rate of vapour deposition, amount of base material, distance between the substrate and spray gun tip, and dopant (Nd) concentration. The structural, optical, electrical and photo-electronic properties of the doped and undoped SnO_2 films were studied. X-ray diffraction studies shows the polycrystalline nature of the films with preferential orientation along the (101), (211) and (301) planes and an average grain size of 100 Å. The optical properties of these films were studied by measuring their optical transmission …

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Unsteady Free Convection Flow With Thermal Radiation Past A Vertical Porous Plate With Newtonian Heating, Promise Mebine, Emmanuel Munakurogha Adigio Jan 2009

Unsteady Free Convection Flow With Thermal Radiation Past A Vertical Porous Plate With Newtonian Heating, Promise Mebine, Emmanuel Munakurogha Adigio

Turkish Journal of Physics

This paper considers exact solutions of unsteady free convection flow with thermal radiation past a vertical porous plate with Newtonian heating. The technique of Laplace transform was employed in deriving the solutions to the governing flow and energy equations. A parametric study of all parameters involved was conducted, and a representative set of results showing the effect of the radiation parameter N, the ratio of uniform suction to characteristic velocity parameter R, and the free convection parameter Gr on the velocity and temperature are illustrated graphically. The skin friction or shear and heat flux are discussed quantitatively. It is evident …

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