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2010

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Articles 6301 - 6330 of 6945

Full-Text Articles in Physical Sciences and Mathematics

Turbulent Mixing In A Strongly Forced Salt Wedge Estuary, David K. Ralston, W. Rockwell Geyer, James A. Lerczak, Malcolm Scully Jan 2010

Turbulent Mixing In A Strongly Forced Salt Wedge Estuary, David K. Ralston, W. Rockwell Geyer, James A. Lerczak, Malcolm Scully

OES Faculty Publications

Turbulent mixing of salt is examined in a shallow salt wedge estuary with strong fluvial and tidal forcing. A numerical model of the Merrimack River estuary is used to quantify turbulent stress, shear production, and buoyancy flux. Little mixing occurs during flood tides despite strong velocities because bottom boundary layer turbulence is dislocated from stratification elevated in the water column. During ebbs, bottom salinity fronts form at a series of bathymetric transitions. At the fronts, near-bottom velocity and shear stress are low, but shear, stress, and buoyancy flux are elevated at the pycnocline. Internal shear layers provide the dominant source …


Automatic Generation Of Music For Inducing Emotive Response, Tony R. Martinez, Kristine Monteith, Dan A. Ventura Jan 2010

Automatic Generation Of Music For Inducing Emotive Response, Tony R. Martinez, Kristine Monteith, Dan A. Ventura

Faculty Publications

We present a system that generates original music designed to match a target emotion. It creates n-gram models, Hidden Markov Models, and other statistical distributions based on musical selections from a corpus representing a given emotion and uses these models to probabilistically generate new musical selections with similar emotional content. This system produces unique and often remarkably musical selections that tend to match a target emotion, performing this task at a level that approaches human competency for the same task.


Finite Element Analysis Of Ring-Shaped Emission Profile In Plasma Bullet, Yukinori Sakiyama, David B. Graves, Julien Jarrige, Mounir Laroussi Jan 2010

Finite Element Analysis Of Ring-Shaped Emission Profile In Plasma Bullet, Yukinori Sakiyama, David B. Graves, Julien Jarrige, Mounir Laroussi

Electrical & Computer Engineering Faculty Publications

Using a one-way coupled model of neutral gas flow and plasma dynamics we report a mechanism to explain the ring-shaped emission pattern that has been observed experimentally in plasma bullets at atmospheric pressure. We solve a fluid model with the local field approximation in one-dimensional cylindrical coordinates, corresponding to a cross-section of a plasma bullet. Pulselike uniform electric field is assumed to be applied perpendicular to the simulation domain. Time and spatially resolved spectroscopic measurements support the simulation results.


Experimental Studies On The Plasma Bullet Propagation And Its Inhibition, Erdinc Karakas, Mounir Laroussi Jan 2010

Experimental Studies On The Plasma Bullet Propagation And Its Inhibition, Erdinc Karakas, Mounir Laroussi

Electrical & Computer Engineering Faculty Publications

Plasma bullets generated by atmospheric pressure low temperature plasma jets have recently been an active research topic due to their unique properties and their enhanced plasma chemistry. In this paper, experimental insights into the plasma bullet lifetime and its velocity are reported. Data obtained from intensified charge-coupled device camera and time-resolved optical emission spectroscopy (OES) elucidated the existence of a weakly ionized channel between the plasma bullet and its source (such as the plasma pencil). Factors responsible for the inhibition of the propagation of the bullet, such as low helium mole fraction, the magnitude of the applied voltage, and the …


Destruction Of Α -Synuclein Based Amyloid Fibrils By A Low Temperature Plasma Jet, Erdinc Karakas, Agatha Munyanyi, Lesley Greene, Mounir Laroussi Jan 2010

Destruction Of Α -Synuclein Based Amyloid Fibrils By A Low Temperature Plasma Jet, Erdinc Karakas, Agatha Munyanyi, Lesley Greene, Mounir Laroussi

Electrical & Computer Engineering Faculty Publications

Amyloid fibrils are ordered beta-sheet aggregates that are associated with a number of neurodegenerative diseases such as Alzheimer and Parkinson. At present, there is no cure for these progressive and debilitating diseases. Here we report initial studies that indicate that low temperature atmospheric pressure plasma can break amyloid fibrils into smaller units in vitro. The plasma was generated by the plasma pencil, a device capable of emitting a long, low temperature plasma plume/jet. This avenue of research may facilitate the development of a plasma-based medical treatment.


Comment On "Superfluid Turbulence From Quantum Kelvin Wave To Classical Kolmogorov Cascades", Jeffrey Yepez, George Vahala, Linda L. Vahala, Min Soe Jan 2010

Comment On "Superfluid Turbulence From Quantum Kelvin Wave To Classical Kolmogorov Cascades", Jeffrey Yepez, George Vahala, Linda L. Vahala, Min Soe

Electrical & Computer Engineering Faculty Publications

No abstract provided.


Design Of Organic Tandem Solar Cells Using Pcpdtbt: Pc61 Bm And P3ht: Pc71bm, Gon Namkoong, Patrick Boland, Keejoo Lee, James Dean Jan 2010

Design Of Organic Tandem Solar Cells Using Pcpdtbt: Pc61 Bm And P3ht: Pc71bm, Gon Namkoong, Patrick Boland, Keejoo Lee, James Dean

Electrical & Computer Engineering Faculty Publications

We conducted optical and electrical simulations with the goal of determining the optimal design for conjugated polymer-fullerene tandem solar cells using poly[2,6-(4,4-bis-(2-ethylhexyl)- 4H-cyclopenta[2,1- b;3,4- b′] dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT): [6,6]-phenyl C61 butyric acid methyl ester (PC61 BM) as a bottom cell and poly(3-hexylthiophene) (P3HT): [6,6]-phenyl C71 butyric acid methyl ester (PC71BM) as a top cell. The effects of photon density, absorption, balanced and unbalanced charge carrier transport, and bimolecular recombination in the two subcells were incorporated into the simulations. We found that the maximum energy conversion efficiency (η) is 9% when charge carrier mobilities in …


Characterization Of Soil Carbon Stabilization In Long-Term Row-Cropped Agro-Ecosystems, Soraya Patricia Alvarado-Ochoa Jan 2010

Characterization Of Soil Carbon Stabilization In Long-Term Row-Cropped Agro-Ecosystems, Soraya Patricia Alvarado-Ochoa

University of Kentucky Doctoral Dissertations

Soil organic matter (SOM) is a dynamic soil property, sensitive and responsive to many factors. The possibility of increasing soil carbon (C) sequestration by changing land use and management practices has been of great interest recently due to concerns with global changes in the atmospheric carbon dioxide (CO2) balance. Nonetheless, as a result of the complex dynamics of SOM, there is still the need for SOM characterization procedures capable of monitoring SOM stabilization, taking into account all the factors involved.

This study characterized SOM stabilization as affected by management practices in three long-term field experiments, considering physical, chemical …


Benthic Ecology From Space: Optics And Net Primary Production In Seagrass And Benthic Algae Across The Great Bahama Bank, Heidi M. Dierssen, Richard C. Zimmerman, Lisa A. Drake, David J. Burdige Jan 2010

Benthic Ecology From Space: Optics And Net Primary Production In Seagrass And Benthic Algae Across The Great Bahama Bank, Heidi M. Dierssen, Richard C. Zimmerman, Lisa A. Drake, David J. Burdige

OES Faculty Publications

Development of repeatable and quantitative tools are necessary for determining the abundance and distribution of different types of benthic habitats, detecting changes to these ecosystems, and determining their role in the global carbon cycle. Here we used ocean color remote sensing techniques to map different major groups of primary producers and estimate net primary productivity (NPP) across Great Bahama Bank (GBB). Field investigations on the northern portion of the GBB in 2004 revealed 3 dominant types of benthic primary producers: seagrass, benthic macroalgae, and microalgae attached to sediment. Laboratory measurements of NPP ranged from barely net autotrophic for grapestone sediment …


A Seasonal Study Of Dissolved Cobalt In The Ross Sea, Antarctica: Micronutrient Behavior, Absence Of Scavenging, And Relationships With Zd, Cd, And P., M. A. Saito, T. J. Goepfert, A. E. Noble, E. M. Bertrand, Peter N. Sedwick, Giacomo R. Ditullio Jan 2010

A Seasonal Study Of Dissolved Cobalt In The Ross Sea, Antarctica: Micronutrient Behavior, Absence Of Scavenging, And Relationships With Zd, Cd, And P., M. A. Saito, T. J. Goepfert, A. E. Noble, E. M. Bertrand, Peter N. Sedwick, Giacomo R. Ditullio

OES Faculty Publications

We report the distribution of cobalt (Co) in the Ross Sea polynya during austral summer 2005-2006 and the following austral spring 2006. The vertical distribution of total dissolved Co (dCo) was similar to soluble reactive phosphate (PO(4)(3-)), with dCo and PO(4)(3-) showing a significant correlation throughout the water column (r(2) = 0.87, 164 samples). A strong seasonal signal for dCo was observed, with most spring samples having concentrations ranging from similar to ~ 45-85 pM, whereas summer dCo values were depleted below these levels by biological activity. Surface transect data from the summer cruise revealed concentrations at the low range …


The Path To Preservation: Using Proteomics To Decipher The Fate Of Diatom Proteins During Microbial Degradation, Brook L. Nunn, Ying S. Ting, Lars Malmström, Yihsuan S. Tsai, Angela Aquier, David R. Goodlett, H. Rodger Harvey Jan 2010

The Path To Preservation: Using Proteomics To Decipher The Fate Of Diatom Proteins During Microbial Degradation, Brook L. Nunn, Ying S. Ting, Lars Malmström, Yihsuan S. Tsai, Angela Aquier, David R. Goodlett, H. Rodger Harvey

OES Faculty Publications

We drew upon recent advances in tandem mass spectrometry-based proteomic analyses in order to examine the proteins that remain after a diatom bloom enters the stationary phase, precipitates out of the photic zone, and is subjected to microbial degradation over a 23-d period within a controlled laboratory environment. Proteins were identified from tandem mass spectra searched against three different protein databases in order to track proteins from Thalassiosira pseudonana and any potential bacterial contributions. A rapid loss of diatom protein was observed over the incubation period; 75% of the proteins initially identified were not detected after 72 h of exposure …


Effect Of The Heterotrophic Dinoflagellate Oxyrrhis Marina And The Copepod Acartia Tonsa On Vertical Carbon Flux In And Around Thin Layers Of The Phytoflagellate Isochrysis Galbana, A. B. Bochdansky, S. M. Bollens, G. C. Rollwagen-Bollens, A. H. Gibson Jan 2010

Effect Of The Heterotrophic Dinoflagellate Oxyrrhis Marina And The Copepod Acartia Tonsa On Vertical Carbon Flux In And Around Thin Layers Of The Phytoflagellate Isochrysis Galbana, A. B. Bochdansky, S. M. Bollens, G. C. Rollwagen-Bollens, A. H. Gibson

OES Faculty Publications

Dynamics of material and energy flow through food webs differ when resources are allocated in patches in comparison to situations in which the same resources are distributed evenly throughout the water column. Thin layers of plankton are special cases of such resource patches. While previous studies have predominantly focused on the response of organisms to these layers, we investigated how 2 types of grazers in turn affect thin layers. In an experimental study with tightly controlled environmental conditions, we monitored the redistribution of particulate organic (POC), dissolved organic (DOC) and inorganic (DIC) carbon from thin layers of Isochrysis galbana. …


Analysis Of Fluvial Suspended Sediment Load Contribution Through Anthropocene History To The South Atlantic Bight Coastal Zone, U.S.A., K Mccarney-Castle, George Voulgaris, A J. Kettner Jan 2010

Analysis Of Fluvial Suspended Sediment Load Contribution Through Anthropocene History To The South Atlantic Bight Coastal Zone, U.S.A., K Mccarney-Castle, George Voulgaris, A J. Kettner

Faculty Publications

Discerning the effects of anthropogenic activities (i.e., reservoir construction, land use change), as opposed to those of natural processes (i.e., climate variability), on suspended sediment flux has become an increasingly difficult challenge. This contribution presents water and suspended sediment flux from five major watersheds that discharge into the southeastern U.S. Atlantic, a region that is currently considered sediment starved. Three periods of Anthropocenetime were defined and evaluated: (1) “pre-European conditions” (1680–1700), (2) “pre-dam conditions" (1905-1925), and (3) "post-dam conditions" (1985-2005). Physical and hydrologic watershed data were used to run a climate-driven hydrological transport numerical model (HydroTrend) to estimate …


Application Of Foreland Basin Detrital-Zircon Geochronology To The Reconstruction Of The Southern And Central Appalachian Orogen, Hyunmee Park, David L. Barbeau Jr, Alan Rickenbaker, Denise Bachmann-Krug, George E. Gehrels Jan 2010

Application Of Foreland Basin Detrital-Zircon Geochronology To The Reconstruction Of The Southern And Central Appalachian Orogen, Hyunmee Park, David L. Barbeau Jr, Alan Rickenbaker, Denise Bachmann-Krug, George E. Gehrels

Faculty Publications

We report the U-Pb age distribution of detrital zircons collected from central and southern Appalachian foreland basin strata, which record changes of sediment provenance in response to the different phases of the Appalachian orogeny. Taconic clastic wedges have predominantly ca. 1080–1180 and ca. 1300–1500 Ma zircons, whereas Acadian clastic wedges contain abundant Paleozoic zircons and minor populations of 550–700 and 1900–2200 Ma zircons consistent with a Gondwanan affinity. Alleghanian clastic wedges contain large populations of ca. 980–1080 Ma and ca. 2700 Ma and older Archean zircons and fewer Paleozoic zircons than occur in the Acadian clastic wedges. The abundance of …


Transition-Metal Ion Exchange Using Poly(Ethylene Glycol) Oligomers As Solvents, Gina M. Canfield, Michael Bizimis, Susan E. Latturner Jan 2010

Transition-Metal Ion Exchange Using Poly(Ethylene Glycol) Oligomers As Solvents, Gina M. Canfield, Michael Bizimis, Susan E. Latturner

Faculty Publications

Poly(ethylene glycol) oligomers have been found to be effective as alternative solvents for the ion exchange of Mn2þ , Fe2 þ , and Co2þ into hydrated and dehydrated Zeolite X (Na80Al80Si112- O384 3 nH2O). When attempted in aqueous solutions, the exchange of these cations quickly leads to destruction of the zeolite structure within 1-2 exchange cycles. However, in PEG oligomer solvents, the structure can be maintained and exchanges of 48% (Co2þ ), 80% (Mn2þ ), and 91% (Fe2þ ) are observed after one cycle under hydrated conditions. When rigorous steps are taken to remove all water from the zeolite before …


Early Detection Of Online Auction Opportunistic Sellers Through The Use Of Negative-Positive Feedback, Gregory J. Reinert Jan 2010

Early Detection Of Online Auction Opportunistic Sellers Through The Use Of Negative-Positive Feedback, Gregory J. Reinert

CCAC Theses and Dissertations

Apparently fraud is a growth industry. The monetary losses from Internet fraud have increased every year since first officially reported by the Internet Crime Complaint Center (IC3) in 2000. Prior research studies and third-party reports of fraud show rates substantially higher than eBay’s reported negative feedback rate of less than 1%. The conclusion is most buyers are withholding reports of negative feedback.

Researchers Nikitov and Stone in a forensic case study of a single opportunistic eBay seller found buyers sometimes embedded negative comments in positive feedback as a means of avoiding retaliation from sellers and damage to their reputation. This …


Assistive Technology Attrition: Identifying Why Teachers Abandon Assistive Technologies, Michael Edward Sharpe Jan 2010

Assistive Technology Attrition: Identifying Why Teachers Abandon Assistive Technologies, Michael Edward Sharpe

CCAC Theses and Dissertations

The study surveyed a sample of K-12 teachers who had used assistive technology (AT) in the classroom to determine answers to five research questions. These were, (1) why the teachers adopted AT, (2) their attitudes and perceptions about its value, (3) challenges they have experienced in adopting AT, (4) whether they have discontinued or decreased use of AT, and, if so, (5) the factors that led to this result.

The study used both quantitative and qualitative methods. For the quantitative aspect, an online survey instrument was developed to answer five research questions. Participants were teachers who had used AT in …


Trust And Trustworthiness: A Framework For Successful Design Of Telemedicine, James Robert Templeton Jan 2010

Trust And Trustworthiness: A Framework For Successful Design Of Telemedicine, James Robert Templeton

CCAC Theses and Dissertations

Trust and its antecedents have been demonstrated as a barrier to the successful adoption of numerous fields of technology, most notably e-commerce, and may be a key factor in the lack of adoption or adaptation in the field of telemedicine. In the medical arena, trust is often formed through the relationships cultivated over time via clinician and patient. Trust and interpersonal relationships may also play a significant role in the adoption of telemedicine. The idea of telemedicine has been explored for nearly 30 years in one form or another. Yet, despite grandiose promises of how it will someday significantly improve …


An Analysis Of The Radio Frequency Identification (Rfid) Technology Implementation Within An Independent Public Library System: A Case Study Of The North Canton, Ohio Public Library, Keith P. Lyons Jan 2010

An Analysis Of The Radio Frequency Identification (Rfid) Technology Implementation Within An Independent Public Library System: A Case Study Of The North Canton, Ohio Public Library, Keith P. Lyons

CCAC Theses and Dissertations

An Analysis of the Radio Frequency Identification (RFID) Technology Implementation within an Independent Public Library System:

A Case Study of the North Canton, Ohio Public Library

by

Keith P. Lyons

June 2010

Public libraries require efficient control systems to maintain accurate inventories, statistics, and records of patron borrowing. Generally, public libraries use barcode technology to accomplish these tasks. Radio frequency identification (RFID) has gained the attention of public library personnel in recent years as a replacement for barcodes. RFID implementation contributes to improved staff productivity, increased operational efficiency, and improved item security as well. While potential benefits are significant, issues …


Developing A Framework For Evaluation Of Corporate Non-Transactional Business-To-Consumer Web Sites: A Descriptive Study, Karen Denise Pate Jan 2010

Developing A Framework For Evaluation Of Corporate Non-Transactional Business-To-Consumer Web Sites: A Descriptive Study, Karen Denise Pate

CCAC Theses and Dissertations

During the soaring information economy of the last decade, organizations spent large sums of money on the development of Web sites without much knowledge of their performance value. In time, organizations realized that measuring Web site performance to determine value was fundamental. For transactional, e-commerce Business-to-Consumer (B2C) Web sites, this effort is straightforward because value is attached to sales. Measuring performance to determine the value of non-transactional B2C Web sites (i.e., sites that provide information, not sales) is more complex.

This study examined the underexplored subject of evaluating non-transactional Web sites. Performance was defined as outcomes ranging from site visitor …


Electromagnetic Structure And Reactions Of Few-Nucleon Systems In Χeft, L. Girlanda, S. Pastore, R. Schiavilla, M. Viviani Jan 2010

Electromagnetic Structure And Reactions Of Few-Nucleon Systems In Χeft, L. Girlanda, S. Pastore, R. Schiavilla, M. Viviani

Physics Faculty Publications

We summarize our recent work dealing with the construction of the nucleon-nucleon potential and associated electromagnetic currents up to one loop in chiral effective field theory (χEFT). The magnetic dipole operators derived from these currents are then used in hybrid calculations of static properties and low-energy radiative capture processes in few-body nuclei. A preliminary set of results are presented for the magnetic moments of the deuteron and trinucleons and thermal neutron captures on p, d, and ³He.


Physician Information Seeking Behaviors: Are Physicians Successful Searchers?, Janice Swiatek-Kelley Jan 2010

Physician Information Seeking Behaviors: Are Physicians Successful Searchers?, Janice Swiatek-Kelley

CCAC Theses and Dissertations

In the recent past, physicians found answers to questions by consulting colleagues, textbooks, and professional journals. Now, the availability of medical information through electronic resources has changed physician information-seeking behaviors. Evidence-based medicine is now the accepted decision-making paradigm, and a physician's ability to locate best practice guidelines through electronic information resources has become an essential skill. As physicians struggle to stay current in the wake of an ever-growing volume of medical information, several electronic resources claim to provide one-stop access to the most current information with correct and complete answers to problems encountered in the practice of health care. The …


The Physical And Dynamical Structure Of Serpens - Two Very Different Sub-(Proto)Clusters, A. Duarte-Cabral, G. A. Fuller, N. Peretto, J. Hatchell, Edwin F. Ladd, J. Buckle, J. Richer, S. F. Graves Jan 2010

The Physical And Dynamical Structure Of Serpens - Two Very Different Sub-(Proto)Clusters, A. Duarte-Cabral, G. A. Fuller, N. Peretto, J. Hatchell, Edwin F. Ladd, J. Buckle, J. Richer, S. F. Graves

Faculty Journal Articles

No abstract provided.


Sequential Incoherence In A Multi-Party Synchronous Computer Mediated Communication For An Introductory Health Informatics Course, Amy Franklin Jan 2010

Sequential Incoherence In A Multi-Party Synchronous Computer Mediated Communication For An Introductory Health Informatics Course, Amy Franklin

Faculty, Staff and Student Publications

Online courses will play a key role in the high-volume Informatics education required to train the personnel that will be necessary to fulfill the health IT needs of the country. Online courses can cause feelings of isolation in students. A common way to address these feelings is to hold synchronous online "chats" for students. Conventional chats, however, can be confusing and impose a high extrinsic cognitive load on their participants that hinders the learning process. In this paper we present a qualitative analysis that shows the causes of this high cognitive load and our solution through the use of a …


Automatic Readability Assessment, Lijun Feng Jan 2010

Automatic Readability Assessment, Lijun Feng

Dissertations, Theses, and Capstone Projects

We describe the development of an automatic tool to assess the readability of text documents. Our readability assessment tool predicts elementary school grade levels of texts with high accuracy. The tool is developed using supervised machine learning techniques on text corpora annotated with grade levels and other indicators of reading difficulty. Various independent variables or features are extracted from texts and used for automatic classification. We systematically explore different feature inventories and evaluate the grade-level prediction of the resulting classifiers. Our evaluation comprises well-known features at various linguistic levels from the existing literature, such as those based on language modeling, …


An Empirically-Based Model For Perspective Selection In Route-Finding Dialogues, Robert J. Ross, Kavita E. Thomas Jan 2010

An Empirically-Based Model For Perspective Selection In Route-Finding Dialogues, Robert J. Ross, Kavita E. Thomas

Conference papers

In this work we aim to computationally model the extent to which certain empirical factors affect spatial perspective selection as used in route-finding dialogues. In such dialogues, both interlocutors need to adopt a spatial perspective in which to describe movement direction. In map-based tasks such as the one we are concerned with, two perspective choices are typically available, i.e., route perspective, where projective terms are defined with respect to the perspective of the route follower themselves, e.g., ``go to your right'', or survey perspective, where projective terms are defined with respect to a global or allocentric perspective, e.g., ``go down'', …


Exploring The Frontier Of Uncertainty Space, Rong Hu, Patrick Lindstrom, Sarah Jane Delany, Brian Mac Namee Jan 2010

Exploring The Frontier Of Uncertainty Space, Rong Hu, Patrick Lindstrom, Sarah Jane Delany, Brian Mac Namee

Conference papers

We aim to investigate methods balancing exploitation with exploration in active learning to improve the performance of uncertainty sampling. Two exploration guided sampling methods are compared to uncertainty sampling on various real-life datasets from the 2010 Active Learning Challenge. Our initial experiments seems to indicate that combining exploration with uncertainty sampling improves performance on certain datasets but not all.


Some Implications Of Chu's 10Ψ10 Generalization Of Bailey's 6Ψ6 Summation Formula, James Mclaughlin, Andrew Sills, Peter Zimmer Jan 2010

Some Implications Of Chu's 10Ψ10 Generalization Of Bailey's 6Ψ6 Summation Formula, James Mclaughlin, Andrew Sills, Peter Zimmer

Mathematical Sciences: Faculty Publications

Lucy Slater used Bailey's 6ψ6 summation formula to derive the Bailey pairs she used to construct her famous list of 130 identities of the Rogers-Ramanujan type.

In the present paper we apply the same techniques to Chu's 10ψ10 generalization of Bailey's formula to produce quite general Bailey pairs. Slater's Bailey pairs are then recovered as special limiting cases of these more general pairs.

In re-examining Slater's work, we find that her Bailey pairs are, for the most part, special cases of more general Bailey pairs containing one or more free parameters. Further, we also find new …


Rademacher-Type Formulas For Partitions And Overpartitions, Andrew Sills Jan 2010

Rademacher-Type Formulas For Partitions And Overpartitions, Andrew Sills

Mathematical Sciences: Faculty Publications

A Rademacher-type convergent series formula which generalizes the Hardy-Ramanujan-Rademacher formula for the number of partitions of n and the Zuckerman formula for the Fourier coefficients of ϑ4_0 | τ_−1 is presented.


Influence Of Alcl_3 On The Optical Properties Of New Synthesized 3-Armed Poly(Methyl Methacrylate) Films, Adnan Kurt Jan 2010

Influence Of Alcl_3 On The Optical Properties Of New Synthesized 3-Armed Poly(Methyl Methacrylate) Films, Adnan Kurt

Turkish Journal of Chemistry

Three-armed poly(methyl methacrylate)[PMMA] was synthesized by atom transfer radical polymerization at 100 °C using benzene-1,3,5-triyl tris(4-(bromomethyl) benzoate as 3-armed initiator and a cuprous(I) bromide/2,2'-bipyridine catalytic system. The characterization of PMMA was confirmed by FT-IR, ^1H-NMR, GPC, DSC, and TGA techniques. Optical absorption measurements were also studied by UV-VIS technique. Transmittance and reflectance measured in the wavelength range 300-700 nm were used to calculate the optical constants. The changes in dispersion and Urbach parameters were investigated as a function of AlCl_3 content. The wide band tails increased in width and the optical energy gap decreased from 2.39 to 1.28 eV as …