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2008

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Articles 121 - 150 of 5860

Full-Text Articles in Physical Sciences and Mathematics

Suppression Pattern Of Neutral Pions At High Transverse Momentum In Au + Au Collisions At Square Root Of Snn = 200 Gev And Constraints On Medium Transport Coefficients, Andrew Marshall Adare, Sergey V. Afanasiev, Christine A. Aidala, N. N. Ajitanand, Yasuyuki Akiba, Gyöngyi Baksay, László A. Baksay, Marcus Hohlmann, S. Rembeczki, Klaus Dehmelt Dec 2008

Suppression Pattern Of Neutral Pions At High Transverse Momentum In Au + Au Collisions At Square Root Of Snn = 200 Gev And Constraints On Medium Transport Coefficients, Andrew Marshall Adare, Sergey V. Afanasiev, Christine A. Aidala, N. N. Ajitanand, Yasuyuki Akiba, Gyöngyi Baksay, László A. Baksay, Marcus Hohlmann, S. Rembeczki, Klaus Dehmelt

Aerospace, Physics, and Space Science Faculty Publications

For Au þ Au collisions at 200 GeV, we measure neutral pion production with good statistics for transverse momentum, pT, up to 20 GeV=c. A fivefold suppression is found, which is essentially constant for 5 < pT < 20 GeV=c. Experimental uncertainties are small enough to constrain any model-dependent parametrization for the transport coefficient of the medium, e.g., hq^i in the parton quenching model. The spectral shape is similar for all collision classes, and the suppression does not saturate in Au þ Au collisions.

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Statistics Of Auroral Langmuir Waves, M. Samara, J. Labelle, I. H. Cairns Dec 2008

Statistics Of Auroral Langmuir Waves, M. Samara, J. Labelle, I. H. Cairns

Dartmouth Scholarship

The Physics of Auroral Zone Electrons II (PHAZE II) sounding rocket was launched in February 1997 into active pre-midnight aurora. The resulting high frequency wave data are dominated by Langmuir waves. Consistent with many previous observations the Langmuir waves are sporadic, occurring in bursts lasting up to a few hundred ms. We compute statistics of the electric field amplitudes of these Langmuir waves, with two results. First, the shape of the distribution of running averages of the electric field amplitudes remains approximately stationary for a large range of widths of running average less than ~0.3 ms and for a large …

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Contamination Cannot Explain The Lack Of Large-Scale Power In The Cosmic Microwave Background Radiation, Emory F. Bunn, Austin Bourdon Dec 2008

Contamination Cannot Explain The Lack Of Large-Scale Power In The Cosmic Microwave Background Radiation, Emory F. Bunn, Austin Bourdon

Physics Faculty Publications

Several anomalies appear to be present in the large-angle cosmic microwave background (CMB) anisotropy maps of the Wilkinson Microwave Anisotropy Probe. One of these is a lack of large-scale power. Because the data otherwise match standard models extremely well, it is natural to consider perturbations of the standard model as possible explanations. We show that, as long as the source of the perturbation is statistically independent of the source of the primary CMB anisotropy, no such model can explain this large-scale power deficit. On the contrary, any such perturbation always reduces the probability of obtaining any given low value of …

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Correction Of Electronic Record For Weighing Bucket Precipitation Gauge Measurements, Anurag Nayak, David G. Chandler, Danny Marks, James P. Mcnamara, Mark Seyfried Dec 2008

Correction Of Electronic Record For Weighing Bucket Precipitation Gauge Measurements, Anurag Nayak, David G. Chandler, Danny Marks, James P. Mcnamara, Mark Seyfried

Geosciences Faculty Publications and Presentations

Electronic sensors generate valuable streams of forcing and validation data for hydrologic models but are often subject to noise which must be removed as part of model input and testing database development. We developed an automated precipitation correction program (APCP) for weighing bucket precipitation gauge records, which are subject to several types of mechanical and electronic noise and discontinuities, including gauge maintenance, missing data, wind vibration, and sensor drift. Corrected cumulative water year precipitation from APCP did not exhibit an error bias and matched measured water year total precipitation within 2.1% for 58 station years tested. Removal of low-amplitude periodic …

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Dynamic Ordering Transitions Of Liquid Crystals Driven By Interfacial Complexes Formed Between Polyanions And Amphiphilic Polyamines, Michael I. Kinsinger, Maren E. Buck, Fernando Campos, David M. Lynn, Nicholas L. Abbott Dec 2008

Dynamic Ordering Transitions Of Liquid Crystals Driven By Interfacial Complexes Formed Between Polyanions And Amphiphilic Polyamines, Michael I. Kinsinger, Maren E. Buck, Fernando Campos, David M. Lynn, Nicholas L. Abbott

Chemistry: Faculty Publications

We report the design of an amphiphilic polyamine (polymer 1) based on poly(2-alkenyl azlactone) that strongly couples the formation of polyelectrolyte complexes at aqueous/liquid crystal (LC) interfaces to ordering transitions in the LC. We demonstrate that the addition of a strong anionic polyelectrolyte to aqueous solutions in contact with polymer 1-laden LC interfaces (prepared by Langmuir-Schaefer transfer of monolayers of polymer 1 onto micrometerthick films of nematic LC) triggers ordering transitions in the LCs. We further demonstrate that changes in the ordering of the LCs (i) are driven by electrostatic interactions between the polyelectrolytes, (ii) involve multivalent interactions between the …

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Simulation And Analysis Of Cadmium Sulfide Nanoparticles, Chad Everett Junkermeier Dec 2008

Simulation And Analysis Of Cadmium Sulfide Nanoparticles, Chad Everett Junkermeier

Theses and Dissertations

I used ab initio molecular dynamics calculations to model cadmium sulfide nanoparticles. The nanoparticles were originaly spherical, bulk-like zinc-blende structures. Constant temperature molecular dynamics calculations reveals that CdS nanoparticles that are about 2 nm in diameter and have unpassivated surfaces are in an amorphous structure with short range order. The nearest neighbor distance on the surface of the nanoparticles being near the wurtzite nearest neighbor distance. I wrote the program xyzSTATS and used its results in justifying the amorphous nanoparticles claim. I also estimated the band gap of the CdS nanoparticles with unpassivated dangling bonds.

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Resonance Raman Interrogation Of The Consequences Of Heme Rotational Disorder In Myoglobin And Its Ligated Derivatives, Freeborn Rwere, Piotr J. Mak, James R. Kincaid Dec 2008

Resonance Raman Interrogation Of The Consequences Of Heme Rotational Disorder In Myoglobin And Its Ligated Derivatives, Freeborn Rwere, Piotr J. Mak, James R. Kincaid

Chemistry Faculty Research and Publications

Resonance Raman spectroscopy is employed to characterize heme site structural changes arising from conformational heterogeneity in deoxyMb and ligated derivatives, i.e., the ferrous CO (MbCO) and ferric cyanide (MbCN) complexes. The spectra for the reversed forms of these derivatives have been extracted from the spectra of reconstituted samples. Dramatic changes in the low-frequency spectra are observed, where newly observed RR modes of the reversed forms are assigned using protohemes that are selectively deuterated at the four methyl groups or at the four methine carbons. Interestingly, while substantial changes in the disposition of the peripheral vinyl and propionate groups can be …

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Reconstructing Three-Dimensional Shape Envelopes From Time-Resolved Small-Angle X-Ray Scattering Data, Jessica Lamb, Lisa W. Kwok, Xiangyun Qiu, Kurt Andresen, Hye Yoon Park, Lois Pollack Dec 2008

Reconstructing Three-Dimensional Shape Envelopes From Time-Resolved Small-Angle X-Ray Scattering Data, Jessica Lamb, Lisa W. Kwok, Xiangyun Qiu, Kurt Andresen, Hye Yoon Park, Lois Pollack

Physics and Astronomy Faculty Publications

Modern computing power has made it possible to reconstruct low-resolution, three-dimensional shapes from solution small-angle X-ray scattering (SAXS) data on biomolecules without a priori knowledge of the structure. In conjunction with rapid mixing techniques, SAXS has been applied to time resolve conformational changes accompanying important biological processes, such as biomolecular folding. In response to the widespread interest in SAXS reconstructions, their value in conjunction with such time-resolved data has been examined. The group I intron from Tetrahymena thermophila and its P4–P6 subdomain are ideal model systems for investigation owing to extensive previous studies, including crystal structures. The goal of this …

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Detection Of An So2 Plume Over Sapporo, Japan From The Eruption Of Mt. Kasatochi Using A Balloon Sounding Technique, Gary A. Morris, Jun Hirokawa, Masatomo Fujiwara, Fumio Hasebe, Keisuke Ishida, Nicholay Krotkov, Mark R. Schoeberl, Walter Komhyr, Barry Lefer, James Flynn Dec 2008

Detection Of An So2 Plume Over Sapporo, Japan From The Eruption Of Mt. Kasatochi Using A Balloon Sounding Technique, Gary A. Morris, Jun Hirokawa, Masatomo Fujiwara, Fumio Hasebe, Keisuke Ishida, Nicholay Krotkov, Mark R. Schoeberl, Walter Komhyr, Barry Lefer, James Flynn

Physics and Astronomy Faculty Presentations

During the month of August 2008, 10 ozonesondes were launched from Hokkaido University in Sapporo, Japan as part of a study to examine regional pollution during the Olympic period. Seven of these soundings included a second instrument with a filter designed to remove SO2 from the intake air stream. SO2 interferes with the normal chemistry of the electrochemical cell (ECC) method for ozone detection, with the net result being that each molecule of SO2 registers as minus one molecule of O3. Thus the unfiltered sonde reports [O3] - [SO2] while the filtered sonde reports [O3]. Laboratory tests prior to launch …

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An Analysis Of Entries In The First Tac Market Design Competition, Jinzhong Niu, Kai Cai, Peter Mcburney, Simon Parsons Dec 2008

An Analysis Of Entries In The First Tac Market Design Competition, Jinzhong Niu, Kai Cai, Peter Mcburney, Simon Parsons

Publications and Research

This paper presents an analysis of entries in the first TAC Market Design Competition final that compares the entries across several scenarios. The analysis complements previous work analyzing the 2007 competition, demonstrating some vulnerabilities of entries that placed highly in the competition. The paper also suggests a simple strategy that would have performed well.

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Sublimital Analysis, Thomas Q. Sibley Dec 2008

Sublimital Analysis, Thomas Q. Sibley

Mathematics Faculty Publications

The Bolzano-Weierstrass theorem asserts, under appropriate circumstances, the convergence of some subsequence of a sequence. While this famous theorem ignores the actual limit of the subsequence, it is natural to investigate such limits. This note characterizes the set of possible limits of subsequences of a given sequence.

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Measuring And Modeling Co2 And H2O Fluxes In Complex Terrain, Diego Andrés Riveros-Iregui, Brian L. Mcglynn Dec 2008

Measuring And Modeling Co2 And H2O Fluxes In Complex Terrain, Diego Andrés Riveros-Iregui, Brian L. Mcglynn

School of Natural Resources: Faculty Publications

The feedbacks between the water and the carbon cycles are of critical importance to global carbon balances. Forests and forest soils in northern latitudes are important carbon pools because of their potential as sinks for atmospheric carbon. However there are significant unknowns related to the effects of hydrologic variability, mountainous terrain, and landscape heterogeneity in controlling soil carbon dioxide (CO2) efflux. Mountainous terrain imposes large spatial heterogeneity in the biophysical controls of soil CO2 production and efflux, including soil temperature, soil water content, vegetation, substrate, and soil physical properties. Further complications are introduced by the superimposed temporal …

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Isotopic Evidence Of Methane Oxidation Across The Surface Water–Ground Water Interface, Diego Andrés Riveros-Iregui, Jennifer Y. King Dec 2008

Isotopic Evidence Of Methane Oxidation Across The Surface Water–Ground Water Interface, Diego Andrés Riveros-Iregui, Jennifer Y. King

School of Natural Resources: Faculty Publications

Biogenic methane (CH4) from wetlands plays a crucial role in the carbon cycle, but the dynamics of dissolved methane flux across the surface water-ground water interface remain poorly understood. This study focused on the effects of spatial transformation of dissolved methane and the role of ground-water recharge in the distribution of dissolved methane across the surface water-ground water interface. Here we present carbon isotopic measurements of biogenic methane and dissolved inorganic carbon (DIC) from the Sarita Wetland, on the St. Paul Campus of the University of Minnesota, and also in six monitoring wells located down gradient from the …

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Transient Analysis Of Heat And Mass Transfer By Natural Convection In Power-Law Fluid Past A Vertical Plate Immersed In A Porous Medium (Numerical Study), Nasser S. Elgazery Dec 2008

Transient Analysis Of Heat And Mass Transfer By Natural Convection In Power-Law Fluid Past A Vertical Plate Immersed In A Porous Medium (Numerical Study), Nasser S. Elgazery

Applications and Applied Mathematics: An International Journal (AAM)

This paper attempted a numerical examination of the problem of unsteady free convection with heat and mass transfer from an isothermal vertical flat plate to a non-Newtonian fluid saturated porous medium. The flow in the porous medium was described via the Darcy-Brinkman-Forchheimer model. The simultaneous development of the problem of boundary layers was obtained numerically by finite difference method. Boundary layer and Boussinesq approximations had been incorporated. Numerical calculations were carried out for the various parameters entering into the problem. Velocity, temperature and concentration profiles were shown graphically and the physical quantities of the problem were given in tables. It …

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A Uniformly Dissipative Scheme For Stationary Statistical Properties Of The Infinite Prandtl Number Model, Wenfang (Wendy) Cheng, Xiaoming Wang Dec 2008

A Uniformly Dissipative Scheme For Stationary Statistical Properties Of The Infinite Prandtl Number Model, Wenfang (Wendy) Cheng, Xiaoming Wang

Mathematics and Statistics Faculty Research & Creative Works

The purpose of this short communication is to announce that a class of numerical schemes, uniformly dissipative approximations, which uniformly preserve the dissipativity of the continuous infinite dimensional dissipative complex (chaotic) systems possess desirable properties in terms of approximating stationary statistics properties. in particular, the stationary statistical properties of these uniformly dissipative schemes converge to those of the continuous system at vanishing mesh size. the idea is illustrated on the infinite Prandtl number model for convection and semi-discretization in time, although the general strategy works for a broad class of dissipative complex systems and fully discretized approximations. as far as …

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A Semi-Implicit Scheme For Stationary Statistical Properties Of The Infinite Prandtl Number Model, Wenfang Cheng, Xiaoming Wang Dec 2008

A Semi-Implicit Scheme For Stationary Statistical Properties Of The Infinite Prandtl Number Model, Wenfang Cheng, Xiaoming Wang

Mathematics and Statistics Faculty Research & Creative Works

We propose a semisecret in time semi-implicit numerical scheme for the infinite Prandtl model for convection. Besides the usual finite time convergence, this scheme enjoys the additional highly desirable feature that the stationary statistical properties of the scheme converge to those of the infinite Prandtl number model at vanishing time stop. One of the key characteristics of the scheme is that it preserves the dissipativity of the infinite Prandtl number model uniformly in terms of the time stop. So far as wo know, this is the first rigorous result on convergence of stationary statistical properties of numerical schemes for infinite …

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Lidar-Derived Benthic Habitat Maps Enable The Quantification Of Potential Dredging Impacts To Coral Reef Ecosystems, Brian K. Walker, Richard E. Dodge, David S. Gilliam Dec 2008

Lidar-Derived Benthic Habitat Maps Enable The Quantification Of Potential Dredging Impacts To Coral Reef Ecosystems, Brian K. Walker, Richard E. Dodge, David S. Gilliam

Marine & Environmental Sciences Faculty Proceedings, Presentations, Speeches, Lectures

An essential component to the analysis of ecosystem services is to characterize and define the major habitats within the area of interest. Aerial photography and/or satellite imagery coupled with geographic information systems (GIS) are frequently used to identify and quantify habitats in open terrestrial ecosystems. However, it is more difficult to successfully apply this methodology to deeper, <20 m, underwater environments. Light detection and ranging (LIDAR), a relatively new remote sensing technology that provides detailed bathymetry, can be used when adequate imagery is not available. This study uses LIDAR as the basis to characterize various benthic habitats in a coral reef ecosystem in order to quantify the habitats for a Habitat Equivalency Analysis (HEA) related to planned dredging activities to expand the Port Everglades entrance channel, Broward County, FL. As part of a regional mapping effort, marine benthic habitats were characterized for Broward County, FL. A mosaic of interpolated, sunshaded, laser bathymetry data served as the foundation upon which acoustic ground discrimination, limited subbottom profiling and aerial photography, and groundtruthing data were added in a GIS to aid in interpretation of benthic habitats. Expert-driven visual interpretation outlined geomorphological features in the LIDAR data at a scale of 1:6000 with a minimum mapping unit of 1 acre. The map of Broward County yielded a high overall accuracy of 89.6%. To quantify the potential dredging impacts, the habitat layer was clipped in GIS to the boundaries of anticipated direct and indirect impacts of the proposed project. Then the area of each clipped polygon was totaled for each habitat by impact type. HEA and Florida’s Uniform Mitigation Assessment Method (UMAM) were performed using these areas. This work would not have been possible using satellite imagery or aerial photography alone and illustrates the capability of relatively new remote sensing technologies to aid in the definition and quantification of habitats for ecosystem service analyses.

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Sfa Weather Station-December 2008, Arthur Temple College Of Forestry And Agriculture, Stephen F. Austin State University Dec 2008

Sfa Weather Station-December 2008, Arthur Temple College Of Forestry And Agriculture, Stephen F. Austin State University

Weather Station Data

No abstract provided.

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Chemistry Division, Sue Cardinal Dec 2008

Chemistry Division, Sue Cardinal

Sci-Tech News

No abstract provided.

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Spatial Misalignment In Time Series Studies Of Air Pollution And Health Data, Roger D. Peng, Michelle L. Bell Dec 2008

Spatial Misalignment In Time Series Studies Of Air Pollution And Health Data, Roger D. Peng, Michelle L. Bell

Johns Hopkins University, Dept. of Biostatistics Working Papers

Time series studies of environmental exposures often involve comparing daily changes in a toxicant measured at a point in space with daily changes in an aggregate measure of health. Spatial misalignment of the exposure and response variables can bias the estimation of health risk and the magnitude of this bias depends on the spatial variation of the exposure of interest. In air pollution epidemiology, there is an increasing focus on estimating the health effects of the chemical components of particulate matter. One issue that is raised by this new focus is the spatial misalignment error introduced by the lack of …

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Planetary Systems Around Close Binary Stars: The Case Of The Very Dusty, Sun-Like, Spectroscopic Binary Bd+20 307, Benjamin Zuckerman, Francis C. Fekel, Michael H. Williamson, Gregory W. Henry, Michael P. Muno Dec 2008

Planetary Systems Around Close Binary Stars: The Case Of The Very Dusty, Sun-Like, Spectroscopic Binary Bd+20 307, Benjamin Zuckerman, Francis C. Fekel, Michael H. Williamson, Gregory W. Henry, Michael P. Muno

Information Systems and Engineering Management Research Publications

Field star BD+20 307 is the dustiest known main-sequence star, based on the fraction of its bolometric luminosity, ~4%, that is emitted at infrared wavelengths. The particles that carry this large infrared luminosity are unusually warm, comparable to the temperature of the zodiacal dust in the solar system, and their existence is likely to be a consequence of a fairly recent collision of large objects such as planets or planetary embryos. Thus, the age of BD+20 307 is potentially of interest in constraining the era of terrestrial planet formation. The present project was initiated with an attempt to derive this …

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Multiwavelength Constraints On The Day–Night Circulation Patterns Of Hd 189733b, Heather Knutson, David Charbonneau, Nicolas B. Cowan, Jonathan J. Fortney, Adam P. Showman, Eric Agol, Gregory W. Henry, Mark E. Everett, Lori E. Allen Dec 2008

Multiwavelength Constraints On The Day–Night Circulation Patterns Of Hd 189733b, Heather Knutson, David Charbonneau, Nicolas B. Cowan, Jonathan J. Fortney, Adam P. Showman, Eric Agol, Gregory W. Henry, Mark E. Everett, Lori E. Allen

Information Systems and Engineering Management Research Publications

We present new Spitzer observations of the phase variation of the hot Jupiter HD 189733b in the MIPS 24 μm bandpass, spanning the same part of the planet's orbit as our previous observations in the IRAC 8 μm bandpass (Knutson et al. 2007). We find that the minimum hemisphere-averaged flux from the planet in this bandpass is 76% ± 3% of the maximum flux; this corresponds to minimum and maximum hemisphere-averaged brightness temperatures of 984 ± 48 K and 1220 ±  47 K, respectively. The planet reaches its maximum flux at an orbital phase of 0.396 ± 0.022, corresponding to …

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Integrating Landscapes That Have Experienced Rural Depopulation And Ecological Homogenization Into Tropical Conservation Planning, Aerin L. Jacob, Ismael Vaccaro, Raja Sengupta, Joel N. Hartter, Colin A. Chapman Dec 2008

Integrating Landscapes That Have Experienced Rural Depopulation And Ecological Homogenization Into Tropical Conservation Planning, Aerin L. Jacob, Ismael Vaccaro, Raja Sengupta, Joel N. Hartter, Colin A. Chapman

Geography

If current trends of declining fertility rates and increasing abandonment of rural land as a result of urbanization continue, this will signal a globally significant transformation with important consequences for policy makers interested in conservation planning. This transformation is presently evident in a number of countries and projections suggest it may occur in the future in many developing countries. We use rates of population growth and urbanization to project population trends in rural areas for 25 example countries. Our projections indicate a general decline in population density that has either occurred already (e.g., Mexico) or may occur in the future …

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Soliton Perturbation Theory For The Modified Kawahara Equation, Anjan Biswas Dec 2008

Soliton Perturbation Theory For The Modified Kawahara Equation, Anjan Biswas

Applications and Applied Mathematics: An International Journal (AAM)

The modified Kawahara equation is studied along with its perturbation terms. The adiabatic dynamics of the soliton amplitude and the velocity of the soliton are obtained by the aid of soliton perturbation theory.

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On The Mixed Sum Of Doubly Infinite And Finite Independent Random Variables, Mridula Garg Dec 2008

On The Mixed Sum Of Doubly Infinite And Finite Independent Random Variables, Mridula Garg

Applications and Applied Mathematics: An International Journal (AAM)

The aim of the present paper is to study the distribution of the mixed sum of two random variables. Here we establish a theorem which gives the probability density function (pdf) of sum of doubly infinite and finite independent random variables. The distribution of the infinite and finite independent random variables is given in the form of corollary. As an application of these results we have obtained a distribution of sum of bilateral exponential variate with triangular, Rayleigh with uniform and Weibull with triangular variate. Some graphs of these distributions have also been given.

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Establishment Of A Chebyshev-Dependent Inhomogeneous Second Order Differential Equation For The Applied Physics-Related Boubaker-Turki Polynomials, Micahel Dada, O. Bamidele Awojoyogbe, Maximilian Hasler, Karem B. Ben Mahmoud, Amine Bannour Dec 2008

Establishment Of A Chebyshev-Dependent Inhomogeneous Second Order Differential Equation For The Applied Physics-Related Boubaker-Turki Polynomials, Micahel Dada, O. Bamidele Awojoyogbe, Maximilian Hasler, Karem B. Ben Mahmoud, Amine Bannour

Applications and Applied Mathematics: An International Journal (AAM)

This paper proposes Chebyshev-dependent inhomogeneous second order differential equation for the m-Boubaker polynomials (or Boubaker-Turki polynomials). This differential equation is also presented as a guide to applied physics studies. A concrete example is given through an attempt to solve the Bloch NMR flow equation inside blood vessels.

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Engineering Division, Daureen Nesdill Dec 2008

Engineering Division, Daureen Nesdill

Sci-Tech News

No abstract provided.

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Effects Of Olfactory And Visual Predators On Nest Success And Nest-Site Selection Of Waterfowl In North Dakota, Jennifer Borgo Dec 2008

Effects Of Olfactory And Visual Predators On Nest Success And Nest-Site Selection Of Waterfowl In North Dakota, Jennifer Borgo

Green Canyon Environmental Research Area, Logan Utah

No abstract provided.

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New Complexities In The Low-State Line Profiles Of Am Herculis, S. Kafka, T. Ribeiro, R. Baptista, R. K. Honeycutt, Jeff W. Robertson Dec 2008

New Complexities In The Low-State Line Profiles Of Am Herculis, S. Kafka, T. Ribeiro, R. Baptista, R. K. Honeycutt, Jeff W. Robertson

Faculty Publications - Physical & Earth Sciences

When accretion temporarily ceases in the polar AM Her, the emission-line profiles are known to develop several distinct components, whose origin remains poorly understood. The new low-state spectra reported here have a more favorable combination of spectral resolution (R ~ 4500), time resolution (~ 3 minute exposures), and S/N than earlier work, revealing additional details of the orbital dependence of the line profiles. The central strong feature of Hα is found to be composed of two components of similar strength, one having K ~ 100 km s-1 and phased with the motion of the secondary star, the other having little …

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Ttl Based Packet Marking For Ip Traceback, Vamsi Paruchuri, Arjan Durresi, Sriram Chellappan Dec 2008

Ttl Based Packet Marking For Ip Traceback, Vamsi Paruchuri, Arjan Durresi, Sriram Chellappan

Computer Science Faculty Research & Creative Works

Distributed Denial of Service Attacks continue to pose major threats to the Internet. in order to traceback attack sources (i.e., IP addresses), a well-studied approach is Probabilistic Packet Marking (PPM), where each intermediate router of a packet marks it with a certain probability, enabling a victim host to traceback the attack source. in a recent study, we showed how attackers can take advantage of probabilistic nature of packet markings in existing PPM schemes to create spoofed marks, hence compromising traceback. in this paper, we propose a new PPM scheme called TTL-Based PPM (TPM) scheme, where each packet is marked with …

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