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2008

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Articles 1 - 30 of 451

Full-Text Articles in Physical Sciences and Mathematics

Laser-Induced Photon-Branched Chain Reaction In A Chemically-Active Gas-Dispersed Medium, Thomas F. George, Renat R. Letfullin, Galen C. Duree Dec 2008

Laser-Induced Photon-Branched Chain Reaction In A Chemically-Active Gas-Dispersed Medium, Thomas F. George, Renat R. Letfullin, Galen C. Duree

Thomas George

A promising avenue in the development of high-energy pulsed chemical HF/DF lasers and amplifiers is the utilization of a photon-branched chain reaction initiated in a two-phase active medium, that is, a medium containing a laser working gas and ultradispersed passivated metal particles. These particles are evaporated under the action of IR laser radiation which results in the appearance of free atoms, their diffusion into the gas, and the development of a photon-branching chain process, which involves photons as both reactants and products. The key obstacle here is the formation of a relatively large volume (in excess of 10^3 cm^3) of the …


Intelligent Multimedia Delivery? It’S A Question Of Semantics, Joseph Thomas-Kerr, I. Burnett, C. Ritz Dec 2008

Intelligent Multimedia Delivery? It’S A Question Of Semantics, Joseph Thomas-Kerr, I. Burnett, C. Ritz

Ian Burnett

Intelligent multimedia delivery uses semantic information about content to enhance the delivery process. This paper proposes a model for intelligent multimedia delivery that advances the state of the art by incorporating a concept of semantic distortion into the delivery optimization process. Furthermore, the model combines format-independence with rate-distortion optimization to provide a flexible framework for intelligent delivery of multimedia in existing and future formats. The paper provides a review of the existing work covering components of the model: scalable coding formats, rate-distortion optimization, format-independent adaptation, and semantic adaptation. It then details the model, and identifies open problems and opportunities for …


Pre-Processing Of Signals Observed From Laser Diode Self-Mixing Intereferometries Using Neural Networks, L. Wei, Joe F. Chicharo, Yanguang Yu, Jiangtao Xi Dec 2008

Pre-Processing Of Signals Observed From Laser Diode Self-Mixing Intereferometries Using Neural Networks, L. Wei, Joe F. Chicharo, Yanguang Yu, Jiangtao Xi

Professor Jiangtao Xi

This paper presents a novel neural network signal interpolation technique in order to eliminate the noise and disturbance associated with the self-mixing signal observed from optical feedback self- mixing interferometry (OFSMI). The proposed technique aims to improve the accuracy for displacement and moving track measurement of a target. The performance of the proposed approach is evaluated by both simulation and experimentation, with simulation revealing a measuring accuracy of A/25 for weak feedback and J20 for moderate feed back.


Carbon-Centric Computing: It Solutions For Climate Change, Aditya K. Ghose, Helen M. Hasan, T. Spedding Dec 2008

Carbon-Centric Computing: It Solutions For Climate Change, Aditya K. Ghose, Helen M. Hasan, T. Spedding

Helen Hasan

IT has a role to play in the current debate on climate change. The current discourse on IT and climate change views IT in a negative light, as a polluter. What remains unrecognized is the critical role of IT as a source of solutions to the climate change problem. We live in a massive, inter-connected Planet Earth Supply Chain. IT provides a range of tools to model, manage and optimize this supply chain. The University of Wollongong Carbon-Centric Computing Initiative (CCCI) seeks to seed a program of research that addresses the climate change problem with a range of computing technologies …


Gravitational Wave Burst Source Direction Estimation Using Time And Amplitude Information, J. Markowitz, M. Zanolin, L. Cadonati, E. Katsavounidis Dec 2008

Gravitational Wave Burst Source Direction Estimation Using Time And Amplitude Information, J. Markowitz, M. Zanolin, L. Cadonati, E. Katsavounidis

Michele Zanolin

In this article we study two problems that arise when using timing and amplitude estimates from a network of interferometers (IFOs) to evaluate the direction of an incident gravitational wave burst (GWB). First, we discuss an angular bias in the least squares timing-based approach that becomes increasingly relevant for moderate to low signal-to-noise ratios. We show how estimates of the arrival time uncertainties in each detector can be used to correct this bias. We also introduce a stand alone parameter estimation algorithm that can improve the arrival time estimation and provide root-sum-squared strain amplitude (h(rss)) values for each site. In …


Switchable Polarization-Independent Liquid-Crystal Fabry-Perot Filter, Enkh-Amgalan Dorjgotov, Achintya K. Bhowmik, Philip J. Bos Dec 2008

Switchable Polarization-Independent Liquid-Crystal Fabry-Perot Filter, Enkh-Amgalan Dorjgotov, Achintya K. Bhowmik, Philip J. Bos

Philip J. Bos

A new approach to a polarization-independent twisted liquid-crystal (LC) structure, where phase difference between orthogonal eigenmodes is tuned to be an integer multiple of 2 pi, is demonstrated with a numerical model. For select wavelengths, polarization-independent operation can be achieved by tuning the twist rate and thickness of the LC cavity Applications can be found in polarization-independent switches and field sequential wavelength selection devices.


Choosing Among Unequals: A Statistical Solution To A Stalemate, Durgesh Chandra Pathak Dec 2008

Choosing Among Unequals: A Statistical Solution To A Stalemate, Durgesh Chandra Pathak

Durgesh Chandra Pathak

In Uttar Pradesh, a new tradition has been started of selecting B.Ed degree holders for a job in Primary Schools and it has been named "Vishisht BTC". Applying their own logic, the ruling governments use variuos criterion to select the candidates. The basic problem is that they have to choose candidates on the basis of merit of their marks in various exams. Now, it is well-established fact that marking is not similar in all universities/colleges. So for a same exam, there can be much inter-university as well as intra-university variation in marks given to students. The point is that student …


Giant Sequoia Insect, Disease, And Ecosystem Interactions, Douglas D. Piirto Dec 2008

Giant Sequoia Insect, Disease, And Ecosystem Interactions, Douglas D. Piirto

Douglas D. Piirto

Individual trees of giant sequoia (Sequoia gigantea [Lindl.] Decne.) have demonstrated a capacity to attain both a long life and very large size. It is not uncommon to find old-growth giant sequoia trees in their native range that are 1,500 years old and over 15 feet in diameter at breast height. The ability of individual giant sequoia trees to survive over such long periods of time has often been attributed to the species high resistance to disease, insect, and fire damage. Such a statement, however, is a gross oversimplification, given broader ecosystem and temporal interactions. For example, why isn't there …


Efficacy Of Herbicide Application Methods Used To Control Tanoak (Lithocarpus Densiflorus) In An Uneven-Aged Coast Redwood Management Context, Douglas D. Piirto, Brenda Smith, Eric K. Huff, Scott T. Robinson Dec 2008

Efficacy Of Herbicide Application Methods Used To Control Tanoak (Lithocarpus Densiflorus) In An Uneven-Aged Coast Redwood Management Context, Douglas D. Piirto, Brenda Smith, Eric K. Huff, Scott T. Robinson

Douglas D. Piirto

Three methods of tanoak (Lithocarpus densiflorus [Hook. & Arn.] Rehd.) control involving the application of the amine or ester form of triclopyr were evaluated in this coast redwood uneven-aged forest management study of herbicides. A cut-stump application with the amine form of triclopyr (Garlon 3A), frill cut with the amine form of triclopyr, basal-bark (outer surface) with the ester form of triclopyr (Garlon 4), and an untreated control were replicated three times. The tanoak control results in Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) and/ or coast redwood (Sequoia sempervirens [D. Don] Endl.) predominated stands obtained in earlier studies …


Cost-Effective Fire Management For Southern California's Chaparral Wilderness: An Analytical Procedure, Chris A. Childers, Douglas D. Piirto Dec 2008

Cost-Effective Fire Management For Southern California's Chaparral Wilderness: An Analytical Procedure, Chris A. Childers, Douglas D. Piirto

Douglas D. Piirto

Fire management has always meant fire suppression to the managers of the chaparral covered southern California National Forests. Today, Forest Service fire management programs must be cost effective, while wilderness fire management objectives are aimed at recreating natural fire regimes. A cost-effectiveness analysis has been developed to compare fire management options for meeting these objectives in California's chaparral wilderness. This paper describes the analytical procedure using examples from a study currently being conducted for the Los Padres National Forest, and discusses some preliminary results.


Fluoranthene, But Not Benzo[A]Pyrene, Interacts With Hypoxia Resulting In Pericardial Effusion And Lordosis In Developing Zebrafish, Cole W. Matson, Alicia R. Timme-Laragy, Richard T. Di Giulio Nov 2008

Fluoranthene, But Not Benzo[A]Pyrene, Interacts With Hypoxia Resulting In Pericardial Effusion And Lordosis In Developing Zebrafish, Cole W. Matson, Alicia R. Timme-Laragy, Richard T. Di Giulio

Alicia R. Timme-Laragy

Previous research has documented several PAHs that interact synergistically, causing severe teratogenicity in developing fish embryos. The coexposure of CYP1A inhibitors (e.g. FL or ANF) with AHR agonists (e.g. BaP or BNF) results in a synergistic increase in toxicity. As with chemical CYP1A inhibitors, it has also been shown that CYP1A morpholinos exacerbate BNF-induced embryotoxicity. We hypothesized that a hypoxia-induced reduction in CYP1A activity in BNF or BaP-exposed zebrafish embryos would similarly enhance pericardial effusion and other developmental abnormalities. BaP, BNF, ANF, and FL exposures, both individually and as BaP+FL or BNF+ANF combinations, were performed under hypoxia and normoxia. CYP1A …


International Terrorism:Role ,Responsibility And Operation Of Media Channles, Ratnesh Dwivedi Mr Nov 2008

International Terrorism:Role ,Responsibility And Operation Of Media Channles, Ratnesh Dwivedi Mr

Ratnesh Dwivedi

"Terrorism" is a term that cannot be given a stable defintion. Or rather, it can, but to do so forstalls any attempt to examine the major feature of its relation to television in the contemporary world. As the central public arena for organising ways of picturing and talking about social and political life, TV plays a pivotal role in the contest between competing defintions, accounts and explanations of terrorism. Which term is used in any particular context is inextricably tied to judgemements about the legitimacy of the action in question and of the political system against which it is directed. …


Tuning Nonlinear Optical Properties In Π-Delocalizable Ruthenium Complexes, T. Christopher Corkery, Sanjay S. Chavan, Marie P. Cifuentes, Marek Samoc, Stijn Van Cleuvenbergen, Inge Asselberghs, Koen Clays, Mark G. Humphrey Nov 2008

Tuning Nonlinear Optical Properties In Π-Delocalizable Ruthenium Complexes, T. Christopher Corkery, Sanjay S. Chavan, Marie P. Cifuentes, Marek Samoc, Stijn Van Cleuvenbergen, Inge Asselberghs, Koen Clays, Mark G. Humphrey

Chris Corkery

No abstract provided.


The Star Formation Law In Nearby Galaxies On Sub-Kpc Scales, F. Bigiel, A. Leroy, F. Walter, E. Brinks, W.J.G. De Blok, B. F. Madore, Michele D. Thornley Nov 2008

The Star Formation Law In Nearby Galaxies On Sub-Kpc Scales, F. Bigiel, A. Leroy, F. Walter, E. Brinks, W.J.G. De Blok, B. F. Madore, Michele D. Thornley

Michele Thornley

We present a comprehensive analysis of the relationship between star formation rate surface density, ΣSFR, and gas surface density, Σgas, at sub-kpc resolution in a sample of 18 nearby galaxies. We use high-resolution H I data from The H I Nearby Galaxy Survey, CO data from HERACLES and the BIMA Survey of Nearby Galaxies, 24 μm data from the Spitzer Space Telescope, and UV data from the Galaxy Evolution Explorer. We target seven spiral galaxies and 11 late-type/dwarf galaxies and investigate how the star formation law differs between the H2 dominated centers of spiral galaxies, …


Regressing Scalar Outcomes On Image Predictors Via Functional Principal Component Regression, Philip T. Reiss Nov 2008

Regressing Scalar Outcomes On Image Predictors Via Functional Principal Component Regression, Philip T. Reiss

Philip T. Reiss

No abstract provided.


All-Optical Suppression Of Relativistic Self-Focusing Of Laser Beams In Plasmas, Serguei Y. Kalmykov, Sunghwan A. Yi, Gennady Shvets Oct 2008

All-Optical Suppression Of Relativistic Self-Focusing Of Laser Beams In Plasmas, Serguei Y. Kalmykov, Sunghwan A. Yi, Gennady Shvets

Serge Youri Kalmykov

It is demonstrated that a catastrophic relativistic self-focusing (RSF) of a high-power laser pulse can be prevented all-optically by a second, much weaker, copropagating pulse. RSF suppression occurs when the difference frequency of the pulses slightly exceeds the electron plasma frequency. The mutual defocusing is caused by the three-dimensional electron density perturbation driven by the laser beat wave slightly above the plasma resonance. A bi-envelope model describing the early stage of the mutual defocusing is derived and analyzed. Later stages, characterized by the presence of a strong electromagnetic cascade, are investigated numerically. Stable propagation of the laser pulse with weakly …


Magnetic Field Measurements Of O Stars With Fors 1 At The Vlt., S. Hubrig, M. Schöller, R. S. Schnerr, J. F. González, R. Ignace, H. F. Henrichs Oct 2008

Magnetic Field Measurements Of O Stars With Fors 1 At The Vlt., S. Hubrig, M. Schöller, R. S. Schnerr, J. F. González, R. Ignace, H. F. Henrichs

Richard Ignace

Context.The presence of magnetic fields in O-type stars has been suspected for a long time. The discovery of these fields would explain a wide range of well documented enigmatic phenomena in massive stars, in particular cyclical wind variability, Hα emission variations, chemical peculiarity, narrow X-ray emission lines, and non-thermal radio/X-ray emission.
Aims.To investigate the incidence of magnetic fields in O stars, we acquired 38 new spectropolarimetric observations with FORS 1 (FOcal Reducer low dispersion Spectrograph) mounted on the 8-m Kueyen telescope of the VLT.
Methods.Spectropolarimetric observations were obtained at different phases for a sample of 13 O …


Homogeneous Dbd In N2: 1) Lif, Talif And Electrical Measurements, N. Gherardi, Et. Es-Sebbar, C. Sarra-Bourret, N. Naudé, F. Massines Oct 2008

Homogeneous Dbd In N2: 1) Lif, Talif And Electrical Measurements, N. Gherardi, Et. Es-Sebbar, C. Sarra-Bourret, N. Naudé, F. Massines

Dr. Et-touhami Es-sebbar

In this paper we compare two different discharges that can be obtained in a DBD configuration, that is to say the filamentary discharge (usual regime in atmospheric DBD) with the Atmospheric Pressure Townsend Discharge (APTD), which is a homogeneous regime obtained in nitrogen atmosphere. The aim is to help in the understanding of the processes which control the transition from one regime to the other. To do so, the discharge is characterized through electrical measurements, coupled with optical diagnostics among which Laser Induced Fluorescence (LIF) for radical density measurements. The influence of the addition of small quantities of additives on …


666 Or 616 (Rev. 13,18), M. G. Michael Oct 2008

666 Or 616 (Rev. 13,18), M. G. Michael

M. G. Michael

No abstract provided.


The Genre Of The Apocalypse: What Are They Saying Now?, M. G. Michael Oct 2008

The Genre Of The Apocalypse: What Are They Saying Now?, M. G. Michael

M. G. Michael

No abstract provided.


Synthesis Of Large Crystal Transition Metal Substituted Zeolite Zsm-5, Tara L. Schaeffer, Scott Kirkby Oct 2008

Synthesis Of Large Crystal Transition Metal Substituted Zeolite Zsm-5, Tara L. Schaeffer, Scott Kirkby

Scott J. Kirkby

 Crystals of ZSM-5 containing Cu, Mn, and Fe have been synthesized up to 85 μm in length along the long axis.
This is 1 to 2 orders of magnitude larger than any previously reported. Phase identification was accomplished by powder XRD. A modified Charnel’s method was used to chelate the transition metal and the aluminum in the synthesis gel. Element alanalysis was performed by ICP-AES, confirming the presence of the metals. The metals are resistant to leaching under ion exchange and, as determined by partial dissolution, incorporated throughout the volume of the crystals. 


Spectra Of Nearby Galaxies Measured With A New Very Broadband Receiver, Gopal Narayanan, Ronald L. Snell, Neal A. Erickson, Aeree Chung, Mark H. Heyer, Min Yun, William M. Irvine Oct 2008

Spectra Of Nearby Galaxies Measured With A New Very Broadband Receiver, Gopal Narayanan, Ronald L. Snell, Neal A. Erickson, Aeree Chung, Mark H. Heyer, Min Yun, William M. Irvine

William M. Irvine

Three-millimeter-wavelength spectra of a number of nearby galaxies have been obtained at the Five College Radio Astronomy Observatory (FCRAO) using a new, very broadband receiver. This instrument, which we call the Redshift Search Receiver, has an instantaneous bandwidth of 36 GHz and operates from 74 to 110.5 GHz. The receiver has been built at UMass/FCRAO to be part of the initial instrumentation for the Large Millimeter Telescope (LMT) and is intended primarily for determination of the redshift of distant, dust-obscured galaxies. It is being tested on the FCRAO 14 m by measuring the 3 mm spectra of a number of …


The Economic Value Of Improved Environmental Health In Victorian Rivers, Chris Lloyd Sep 2008

The Economic Value Of Improved Environmental Health In Victorian Rivers, Chris Lloyd

Chris J. Lloyd

The non market valuation technique known as choice modelling was used to general benefit estimates for a selection of hypothetical environmental improvements Victorian Rivers. Monetary values were estimated for four attributed of improvements. The relevance of the approach to management and policy issues is demonstrated.


Model-Driven Performance Analysis, Gabriel A. Moreno, Paulo Merson Sep 2008

Model-Driven Performance Analysis, Gabriel A. Moreno, Paulo Merson

Gabriel A. Moreno

Model-Driven Engineering (MDE) is an approach to develop software systems by creating models and applying automated transformations to them to ultimately generate the implementation for a target platform. Although the main focus of MDE is on the generation of code, it is also necessary to support the analysis of the designs with respect to quality attributes such as performance. To complement the model-to-implementation path of MDE approaches, an MDE tool infrastructure should provide what we call model-driven analysis. This paper describes an approach to model-driven analysis based on reasoning frameworks. In particular, it describes a performance reasoning framework that can …


Estimated P-Values In Discrete Models: Asymptotic And Non-Asymptotic Effects, Chris Lloyd Sep 2008

Estimated P-Values In Discrete Models: Asymptotic And Non-Asymptotic Effects, Chris Lloyd

Chris J. Lloyd

The exact null distribution of a P-value typically depends on nuisance parameters unspecified under the null. For discrete models and standard approximate P-values, this dependence can be quite strong. The estimated (or bootstrap) P-value is the exact probability of the P-value being no larger than its observed value, with the null estimate of the nuisance parameter substituted. For continuous models, it is known that such `bootstrap' P-values deviate from uniformity by terms of order m^{-3/2}, where m is a measure of sample size. The main difficulty with discrete models is the breakdown of asymptotics near the boundary. The aim of …


Transcriptional Responses To Estrogen And Progesterone In Mammary Gland Identify Networks Regulating P53 Activity, Shaolei Lu, Klaus A. Becker, Mary J. Hagen, Haoheng Yan, Amy L. Roberts, Lesley A. Mathews, Sallie S. Schneider, Hava Siegelmann, Kyle J. Macbeth, Stephen M. Tirrell, Jeffrey L. Blanchard, D. Joseph Jerry Sep 2008

Transcriptional Responses To Estrogen And Progesterone In Mammary Gland Identify Networks Regulating P53 Activity, Shaolei Lu, Klaus A. Becker, Mary J. Hagen, Haoheng Yan, Amy L. Roberts, Lesley A. Mathews, Sallie S. Schneider, Hava Siegelmann, Kyle J. Macbeth, Stephen M. Tirrell, Jeffrey L. Blanchard, D. Joseph Jerry

Hava Siegelmann

Estrogen and progestins are essential for mammary growth and differentiation but also enhance the activity of the p53 tumor suppressor protein in the mammary epithelium. However, the pathways by which these hormones regulate p53 activity are unknown. Microarrays were used to profile the transcriptional changes within the mammary gland after administration of either vehicle, 17β-estradiol (E), or progesterone (P) individually and combined (EP). Treatment with EP yielded 1182 unique genes that were differentially expressed compared to the vehicle-treated group. Although 30% of genes were responsive to either E or P individually, combined treatment with both EP had a synergistic effect …


More Powerful Exact Tests Of Equivalence, Chris Lloyd Sep 2008

More Powerful Exact Tests Of Equivalence, Chris Lloyd

Chris J. Lloyd

In randomized clinical trials, it is often required to demonstrate that a new medical treatment is neither substantially worse nor better than a standard reference treatment. Formal testing of such `equivalence hypotheses' is typcialyl done by combining two one-sided tests (TOST). A quite diferent strand of research has demonstrated that maximising P-values over nuisance parameters produces optimal tests (Rohmel and Mansmann (1999) and Lloyd (2008a)). In this paper we point out that, even if the one-sided tests are exact and optimal, the TOST will generally be conservative and requires a further adjustment to remove this conservatism. The appropriate procedure is …


Factors Influencing Farmers’ Willingness To Protect Groundwater From Nonpoint Sources Of Pollution In The Lower Bhavani River Basin, Tamil Nadu, India, Sacchidananda Mukherjee Sep 2008

Factors Influencing Farmers’ Willingness To Protect Groundwater From Nonpoint Sources Of Pollution In The Lower Bhavani River Basin, Tamil Nadu, India, Sacchidananda Mukherjee

Sacchidananda Mukherjee

Farmers' perceptions about groundwater and drinking water quality are important, which influence their willingness to adopt protection measures either individually or collectively. This study attempts to capture the factors influencing farmers’ perceptions and their willingness to protect groundwater from nonpoint sources of pollution, and their willingness to support the local government to supply drinking water through alternative arrangements. Six villages are identified in the Lower Bhavani River Basin, Tamil Nadu, India on the basis of their long-term groundwater nitrate concentrations and sources of irrigation. A pre-structured questionnaire survey (face-to-face interviews) has been administered to 395 farm-households across six villages during …


Oscillating Regime In Carbonylation Reaction Of Propargyl Alcohol (In Russian), Sergey N. Gorodsky, Anatoly V. Kurdiukov, Oleg N. Temkin Sep 2008

Oscillating Regime In Carbonylation Reaction Of Propargyl Alcohol (In Russian), Sergey N. Gorodsky, Anatoly V. Kurdiukov, Oleg N. Temkin

Sergey N. Gorodsky

No abstract provided.


Word Sense Disambiguation In Biomedical Ontologies With Term Co-Occurrence Analysis And Document Clustering, Bill Andreopoulos, Dimitra Alexopoulou, Michael Schroeder Sep 2008

Word Sense Disambiguation In Biomedical Ontologies With Term Co-Occurrence Analysis And Document Clustering, Bill Andreopoulos, Dimitra Alexopoulou, Michael Schroeder

William B. Andreopoulos

With more and more genomes being sequenced, a lot of effort is devoted to their annotation with terms from controlled vocabularies such as the GeneOntology. Manual annotation based on relevant literature is tedious, but automation of this process is difficult. One particularly challenging problem is word sense disambiguation. Terms such as |development| can refer to developmental biology or to the more general sense. Here, we present two approaches to address this problem by using term co-occurrences and document clustering. To evaluate our method we defined a corpus of 331 documents on development and developmental biology. Term co-occurrence analysis achieves an …