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2007

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Articles 151 - 180 of 5716

Full-Text Articles in Physical Sciences and Mathematics

Managing Analysis, David Shaw Dec 2007

Managing Analysis, David Shaw

Australian Information Warfare and Security Conference

The Intelligence profession requires effective management to function properly and professional discourse highlights the changing nature of intelligence work. Highlighted “failures” are linked to organizational structures and ethos, and proposals to address the problems include discussion of human and organizational factors with recommendations that address the issues. However, optimising the intelligence process may not be a simple case of applying management techniques as the work relies substantially on individual endeavour. Innovative management techniques are needed and these should be grounded in recognising the peculiar nature of analysis and the skill set required.

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Mathematically Modeling Pcr: An Asymptotic Approximation With Potential For Optimization, Martha J. Garlick Dec 2007

Mathematically Modeling Pcr: An Asymptotic Approximation With Potential For Optimization, Martha J. Garlick

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

A mathematical model for PCR (Polymerase Chain Reaction) is developed using the law of mass action. Differential equations are written from the chemical equations, preserving the detail of the complementary DNA single strand being extended one bas e pair at a time. The equations for the annealing stage are solved analytically. The method of multiple scales is used to approximate solutions for the extension stage. A map is then developed from the solutions to simulate PCR. The advantage of this model is the ability to use the map to optimize the process. Our results suggest that dynamically optimizing the extension …

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Effects Of Water Vapor On The Kinetics Of The Methylperoxy Radical Self-Reaction And Reaction With Hydroperoxy, Alecia Mower Dec 2007

Effects Of Water Vapor On The Kinetics Of The Methylperoxy Radical Self-Reaction And Reaction With Hydroperoxy, Alecia Mower

Theses and Dissertations

The gas phase reactions of CH3O2 + CH3O2, HO2 + HO2, and CH3O2 + HO2 in the presence of water vapor have been studied at temperatures between 263 and 303 K using laser flash photolysis coupled with UV time-resolved absorption detection at 220 nm and 260 nm. Water vapor concentration was quantified using tunable diode laser spectroscopy operating in the mid-IR. The HO2 self-reaction rate constant is significantly enhanced by water vapor, consistent with what others have reported, whereas CH3O2 self-reaction and the cross-reaction (CH3O2 + HO2) rate constants are nearly unaffected. The enhancement in the HO2 self-reaction rate coefficient …

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). Size Dependency Of The Elastic Modulus Of Zno Nanowires: Surface Stress Effect, Guofeng Wang, Xiaodong Li Dec 2007

). Size Dependency Of The Elastic Modulus Of Zno Nanowires: Surface Stress Effect, Guofeng Wang, Xiaodong Li

Faculty Publications

Relation between the elastic modulus and the diameter (D) of ZnOnanowires was elucidated using a model with the calculated ZnOsurface stresses as input. We predict for ZnOnanowires due to surface stress effect: (1) when D>20nm, the elastic modulus would be lower than the bulk modulus and decrease with the decreasing diameter, (2) when 20nm>D>2nm, the nanowires with a longer length and a wurtzite crystal structure could be mechanically unstable, and (3) when D<2nm, the elastic modulus would be higher than that of the bulk value and increase with a decrease in nanowire diameter.

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The Rate And Timing Of Direct Mountain Front Recharge In An Arid Environment, Silver Island Mountains, Utah, Gregory T. Carling Dec 2007

The Rate And Timing Of Direct Mountain Front Recharge In An Arid Environment, Silver Island Mountains, Utah, Gregory T. Carling

Theses and Dissertations

Direct mountain front recharge (MFR), water table recharge at the base of the mountain front, was evaluated on the arid (<250 mm/yr precipitation) Silver Island Mountains by comparing mountain precipitation to groundwater response. Direct MFR contributions were assessed on two catchments, one bedrock (i.e., mountain block) dominated and the other alluvial fan (i.e., mountain front) dominated. Catchment precipitation and shallow groundwater levels at each catchment outlet were measured for a 24 month period beginning October 2005. This time period captured one complete hydrologic cycle (December 2005-February 2007) for which annual and seasonal direct MFR rates were calculated. Annual direct MFR was calculated using a modified version of the water table fluctuation (WTF) method as 0.015-0.016% of precipitation on both catchments, with seasonal variations of 0% in summer up to 0.023% in winter, spring and fall. Seasonal direct MFR contributions are similar on the bedrock and the alluvial fan dominated catchments, with a notable exception during fall 2006 when direct MFR was twice as effective on the bedrock dominated system than on the alluvial fan dominated system (0.022% and 0.011% of precipitation, respectively). Darcy's law calculations show similarly low annual direct MFR contributions (0.013-0.032% of precipitation) as those calculated by the WTF method. Calculated direct MFR is 10% or less than typical calculated combined MFR (near surface recharge and deep underflow from the mountain block) for similar terrains and climates, and is only 3.5% of the combined MFR for the Silver Island Mountains as calculated by the Maxey-Eakin model. However, based on total recharge to the adjacent playa, it is apparent that the Maxey-Eakin model overestimates combined MFR, and the small calculated direct MFR is at least 50% of combined MFR. Despite some uncertainty in the numerical results, several patterns are evident in the data. The data show that direct MFR occurs in response to small rainfall events throughout much of the year, and that snowmelt is not necessary to produce direct MFR. The data also show that direct MFR responds more quickly and flushes through the system faster on the alluvial fan catchment than on the bedrock catchment.

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Commercial Critical Systems And Critical Infrastructure Protection: A Future Research Agenda, Matthew J. Warren, Shona Leitch Dec 2007

Commercial Critical Systems And Critical Infrastructure Protection: A Future Research Agenda, Matthew J. Warren, Shona Leitch

Australian Information Warfare and Security Conference

Secure management of Australia’s commercial critical infrastructure presents ongoing challenges to owners and the government. Although it is currently managed through high-level information sharing via collaboration, but does this suit the commercial sector. One of the issues facing Australia is that the majority of critical infrastructure resides under the control of the business sector and certain aspects such of the critical infrastructure such as Supply Chain Management (SCM) systems are distributed entities and not a single entity. The paper focuses upon the security issues associated with SCM systems and critical infrastructure protection

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Space As A New Sphere Of Future Information Warfare, Martti Lehto Dec 2007

Space As A New Sphere Of Future Information Warfare, Martti Lehto

Australian Information Warfare and Security Conference

Air power has seen constant development from the Wright Flyer’s first flight at Kitty Hawk on December 17, 1903 via the advent of the jet age with the service entry of the Messerschmitt Me 262 in 1942, to today’s multirole fighters (F-35 Joint Strike Fighter) and stealth aircraft (B-2 Spirit multi-role bomber). As a result of this evolution of one hundred years air power has emerged as a central component in power projection. As General William Mitchell said: ”Neither armies nor navies can exist unless the air is controlled over them.” (Mitchell 1925, xv)We have witnessed a corresponding development in …

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Prevention Of Staphylococcus Epidermidis Biofilm Formation Using A Low-Temperature Processed Silver-Doped Phenyltriethoxysilane Sol–Gel Coating, Niall Stobie, Brendan Duffy, Declan Mccormack, John Colreavy, Martha Hidalgo, Patrick Mchale, Steven Hinder Dec 2007

Prevention Of Staphylococcus Epidermidis Biofilm Formation Using A Low-Temperature Processed Silver-Doped Phenyltriethoxysilane Sol–Gel Coating, Niall Stobie, Brendan Duffy, Declan Mccormack, John Colreavy, Martha Hidalgo, Patrick Mchale, Steven Hinder

Articles

Sol–gel coatings which elute bioactive silver ions are presented as a potential solution to the problem of biofilm formation on indwelling surfaces. There is evidence that high-temperature processing of such materials can lead to diffusion of silver away from the coating surface, reducing the amount of available silver. In this study, we report the biofilm inhibition of a Staphylococcus epidermidis biofilm using a low-temperature processed silver-doped phenyltriethoxysilane sol–gel coating. The incorporation of a silver salt into a sol–gel matrix resulted in an initial high release of silver in de-ionised water and physiological buffered saline (PBS), followed by a lower sustained …

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Fabrication Of Pillar-Structured Thermal Neutron Detectors, Rebecca J. Nikolić, Adam M. Conway, Catherine E. Reinhardt, Robert T. Graff, Tzu Fang Wang, Nirmalendu Deo, Chin Li Cheung Dec 2007

Fabrication Of Pillar-Structured Thermal Neutron Detectors, Rebecca J. Nikolić, Adam M. Conway, Catherine E. Reinhardt, Robert T. Graff, Tzu Fang Wang, Nirmalendu Deo, Chin Li Cheung

Barry Chin Li Cheung Publications

Pillar detector is an innovative solid state device structure that leverages advanced semiconductor fabrication technology to produce a device for thermal neutron detection. State-of-the-art thermal neutron detectors have shortcomings in achieving simultaneously high efficiency, low operating voltage while maintaining adequate fieldability performance. By using a 3-dimensional silicon PIN diode pillar array filled with isotopic boron 10, (10B) a high efficiency device is theoretically possible. The fabricated pillar structures reported in this work are composed of 2 μm diameter silicon pillars with a 4 μm pitch and pillar heights of 6 and 12 μm. The pillar detector with a …

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Changes In The Statistical Properties Of Stochastic Anisotropic Electromagnetic Beams On Propagation In The Turbulent Atmosphere, Xinyue Du, Daomu Zhao, Olga Korotkova Dec 2007

Changes In The Statistical Properties Of Stochastic Anisotropic Electromagnetic Beams On Propagation In The Turbulent Atmosphere, Xinyue Du, Daomu Zhao, Olga Korotkova

Physics Articles and Papers

We report analytic formulas for the elements of the e 2 X 2 cross-spectral density matrix of a stochastic electromagnetic anisotropic beam propagating through the turbulent atmosphere with the help of vector integration. From these formulas the changes in the spectral density (spectrum), in the spectral degree of polarization, and in the spectral degree of coherence of such a beam on propagation are determined. As an example, these quantities are calculated for a so-called anisotropic electromagnetic Gaussian Schell-model beam propagating in the isotropic and homogeneous atmosphere. In particular, it is shown numerically that for a beam of this class, unlike …

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Application Of Correlation-Induced Spectral Changes To Inverse Scattering, Daomu Zhao, Olga Korotkova, Emil Wolf Dec 2007

Application Of Correlation-Induced Spectral Changes To Inverse Scattering, Daomu Zhao, Olga Korotkova, Emil Wolf

Physics Articles and Papers

It is shown how the phenomenon of correlation-induced spectral changes generated on scattering of a polychromatic plane wave on a spatially homogeneous random medium may be used to determine the correlation function of the scattering potential of the medium.

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Construction And Analysis Of An Ozone Profile Climatology Over Houston, Texas, Gary A. Morris, Anne M. Thompson, Ryan Perna, John Yorks, Bernhard Rappengluek, Greg Ostermann, Barry Lefer, Renee Boudreaux, Aaron Chow, Bonnie Ford, Elizabeth Thompson, Scott Hersey, Brittni Emery Dec 2007

Construction And Analysis Of An Ozone Profile Climatology Over Houston, Texas, Gary A. Morris, Anne M. Thompson, Ryan Perna, John Yorks, Bernhard Rappengluek, Greg Ostermann, Barry Lefer, Renee Boudreaux, Aaron Chow, Bonnie Ford, Elizabeth Thompson, Scott Hersey, Brittni Emery

Physics and Astronomy Faculty Presentations

Since the summer of 2004, over 200 ozonesondes have been launched from the campuses of Rice University or the University of Houston (29.7 N, 95.3 W), each about 3 miles from downtown Houston. These sounding launches have been sponsored by NASA, the Shell Center for Sustainability of Rice University, and the Texas Commissions for Environmental Quality as part of a large effort to understand Houston’s ozone problem. Data from these soundings have provided valuable insight into the seasonal and diurnal variations of the vertical ozone distribution and their relationship to changes in atmospheric conditions. In this presentation, we show annual …

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Effects Of An Inserted Endoscope On Chyme Movement In Small Intestine – A Theoretical Model, V. P. Srivastava Dec 2007

Effects Of An Inserted Endoscope On Chyme Movement In Small Intestine – A Theoretical Model, V. P. Srivastava

Applications and Applied Mathematics: An International Journal (AAM)

The effects of an inserted endoscope on chyme movement in small intestine (gastrointestinal tract) have been investigated. The flow of chyme is induced by a progressive wave of area contraction along the length of intestinal wall under long wavelength approximation. It is found that the chyme movement is significantly influenced due to the presence of the endoscope. The pressure drop assumes lower values for higher values of the endoscope radius for small flow rates but the property reverses with increasing flow rates. The friction forces at intestinal wall and endoscope possess character similar to the pressure drop for any given …

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Sfa Weather Station-December 2007, Arthur Temple College Of Forestry And Agriculture, Stephen F. Austin State University Dec 2007

Sfa Weather Station-December 2007, Arthur Temple College Of Forestry And Agriculture, Stephen F. Austin State University

Weather Station Data

No abstract provided.

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From The Editor, Susan Fingerman Dec 2007

From The Editor, Susan Fingerman

Sci-Tech News

No abstract provided.

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Aerospace Section, Amy C. Smith Dec 2007

Aerospace Section, Amy C. Smith

Sci-Tech News

No abstract provided.

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New Science And Technology Journals, Earl Mounts Dec 2007

New Science And Technology Journals, Earl Mounts

Sci-Tech News

No abstract provided.

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Web Reviews, Diane F. Brenes Dec 2007

Web Reviews, Diane F. Brenes

Sci-Tech News

No abstract provided.

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Full Issue: Vol. 61, No. 4 Dec 2007

Full Issue: Vol. 61, No. 4

Sci-Tech News

No abstract provided.

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Bayesian Analysis For Penalized Spline Regression Using Win Bugs, Ciprian M. Crainiceanu, David Ruppert, M.P. Wand Dec 2007

Bayesian Analysis For Penalized Spline Regression Using Win Bugs, Ciprian M. Crainiceanu, David Ruppert, M.P. Wand

Johns Hopkins University, Dept. of Biostatistics Working Papers

Penalized splines can be viewed as BLUPs in a mixed model framework, which allows the use of mixed model software for smoothing. Thus, software originally developed for Bayesian analysis of mixed models can be used for penalized spline regression. Bayesian inference for nonparametric models enjoys the flexibility of nonparametric models and the exact inference provided by the Bayesian inferential machinery. This paper provides a simple, yet comprehensive, set of programs for the implementation of nonparametric Bayesian analysis in WinBUGS. MCMC mixing is substantially improved from the previous versions by using low{rank thin{plate splines instead of truncated polynomial basis. Simulation time …

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On The Asymptotic Stability Of Linear Volterra Difference Equations Of Convolution Type, Saber Elaydi, E Messina, A Vecchio Dec 2007

On The Asymptotic Stability Of Linear Volterra Difference Equations Of Convolution Type, Saber Elaydi, E Messina, A Vecchio

Mathematics Faculty Research

We show that the condition |a| + |∑+∞l=0bl| < 1 is not necessary, though sufficient, for the asymptotic stability of xn+1 = axn + ∑+∞l=0bn-lxl. We prove the existence of a class of Volterra difference equations (VDEs) that violate this condition but whose zero solutions are asymptotically stable.

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Two Jovian-Mass Planets In Earthlike Orbits, Sarah E. Robinson, Gregory Laughlin, Steve Vogt, Debra A. Fischer, R. Paul Butler, Geoffrey W. Marcy, Gregory W. Henry, Peter Driscoll, Genya Takeda, John A. Johnson Dec 2007

Two Jovian-Mass Planets In Earthlike Orbits, Sarah E. Robinson, Gregory Laughlin, Steve Vogt, Debra A. Fischer, R. Paul Butler, Geoffrey W. Marcy, Gregory W. Henry, Peter Driscoll, Genya Takeda, John A. Johnson

Information Systems and Engineering Management Research Publications

We report the discovery of two new planets: a 1.94 MJup planet in a 1.8 yr orbit of HD 5319, and a 2.51 MJup planet in a 1.1 yr orbit of HD 75898. The measured eccentricities are 0.12 for HD 5319b and 0.10 for HD 75898b, and Markov chain Monte Carlo simulations based on the derived orbital parameters indicate that the radial velocities of both stars are consistent with circular planet orbits. With low eccentricity and 1 AU < a < 2 AU, our new planets have orbits similar to terrestrial planets in the solar system. The radial velocity residuals of both stars have significant trends, likely arising from substellar or low-mass stellar companions.

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Separation Of Spatial And Temporal Structure Of Auroral Particle Precipitation, A. Boudouridis, Harlan E. Spence Dec 2007

Separation Of Spatial And Temporal Structure Of Auroral Particle Precipitation, A. Boudouridis, Harlan E. Spence

Physics & Astronomy

[1] Knowledge of the dominant temporal and spatial scales of auroral features is instrumental in understanding the various mechanisms responsible for auroral particle precipitation. Single spacecraft data always suffer from temporal/spatial ambiguity. In an effort to separate the temporal and spatial variations of the aurora, we use electron and ion precipitation data from two co-orbiting satellites, F6 and F8 of the Defense Meteorological Satellite Program (DMSP). The two spacecraft have almost identical polar orbits with a small difference in period. As a result the time difference between the two measurements varies with time. We use two statistical tools in order …

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Age-Structured Population Model With Cannibalism, Mmohammed El-Doma Dec 2007

Age-Structured Population Model With Cannibalism, Mmohammed El-Doma

Applications and Applied Mathematics: An International Journal (AAM)

An age-structured population model with cannibalism is investigated. We determine the steady states and study the local asymptotic stability as well as the global stability. The results in this paper generalize previous results.

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Stability Analysis For The Gurtin-Maccamy’S Age-Structured Population Dynamics Model, Mohammed El-Doma Dec 2007

Stability Analysis For The Gurtin-Maccamy’S Age-Structured Population Dynamics Model, Mohammed El-Doma

Applications and Applied Mathematics: An International Journal (AAM)

The stability of the Gurtin-MacCamy’s age-structured population dynamics model is investigated. We determine the steady states and study their stability. The results in this paper generalize previous results.

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On Mathematical Modeling, Nonlinear Properties And Stability Of Secondary Flow In A Dendrite Layer, D. N. Riahi Dec 2007

On Mathematical Modeling, Nonlinear Properties And Stability Of Secondary Flow In A Dendrite Layer, D. N. Riahi

Applications and Applied Mathematics: An International Journal (AAM)

This paper studies instabilities in the flow of melt within a horizontal dendrite layer with deformed upper boundary and in the presence or absence of rotation during the solidification of a binary alloy. In the presence of rotation, it is assumed that the layer is rotating about a vertical axis at a constant angular velocity. Linear and weakly nonlinear stability analyses provide results about various flow features such as the critical mode of convection, neutral stability curve, preferred flow pattern and the solid fraction distribution within the dendrite layer. The preferred shape of the deformed upper boundary of the layer, …

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Predicting Magnetospheric Dynamics With A Coupled Sun‐To‐Earth Model: Challenges And First Results, V. G. Merkin, M. J. Owens, Harlan E. Spence, W. J. Hughes, J. M. Quinn Dec 2007

Predicting Magnetospheric Dynamics With A Coupled Sun‐To‐Earth Model: Challenges And First Results, V. G. Merkin, M. J. Owens, Harlan E. Spence, W. J. Hughes, J. M. Quinn

Physics & Astronomy

[1] Results from the first Sun-to-Earth coupled numerical model developed at the Center for Integrated Space Weather Modeling are presented. The model simulates physical processes occurring in space spanning from the corona of the Sun to the Earth's ionosphere, and it represents the first step toward creating a physics-based numerical tool for predicting space weather conditions in the near-Earth environment. Two 6- to 7-d intervals, representing different heliospheric conditions in terms of the three-dimensional configuration of the heliospheric current sheet, are chosen for simulations. These conditions lead to drastically different responses of the simulated magnetosphere-ionosphere system, emphasizing, on the one …

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2007 Annual Conference Reports Dec 2007

2007 Annual Conference Reports

Sci-Tech News

No abstract provided.

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On The Cover Dec 2007

On The Cover

Sci-Tech News

No abstract provided.

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Division Officers And Boards Dec 2007

Division Officers And Boards

Sci-Tech News

No abstract provided.

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