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2007

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Articles 3721 - 3750 of 6758

Full-Text Articles in Physical Sciences and Mathematics

Review: A Creationist Review And Preliminary Analysis Of The History, Geology, Climate, And Biology Of The Galápagos Islands, Timothy R. Brophy Feb 2007

Review: A Creationist Review And Preliminary Analysis Of The History, Geology, Climate, And Biology Of The Galápagos Islands, Timothy R. Brophy

Faculty Publications and Presentations

No abstract provided.

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Focusing Capillary Optics For Use In Solution Small-Angle X-Ray Scattering, Jessica S. Lamb, Sterling Cornaby, Kurt Andresen, Lisa W. Kwok, Hye Yoon Park, Xiangyun Qiu, Detlef-M. Smilgies, Donald H. Bilderback, Lois Pollack Feb 2007

Focusing Capillary Optics For Use In Solution Small-Angle X-Ray Scattering, Jessica S. Lamb, Sterling Cornaby, Kurt Andresen, Lisa W. Kwok, Hye Yoon Park, Xiangyun Qiu, Detlef-M. Smilgies, Donald H. Bilderback, Lois Pollack

Physics and Astronomy Faculty Publications

Measurements of the global conformation of macromolecules can be carried out using small-angle X-ray scattering (SAXS). Glass focusing capillaries, manufactured at the Cornell High Energy Synchrotron Source (CHESS), have been successfully employed for SAXS measurements on the heme protein cytochrome c. These capillaries provide high X-ray flux into a spot size of tens of micrometres, permitting short exposures of small-volume samples. Such a capability is ideal for use in conjunction with microfluidic mixers, where time resolution may be determined by beam size and sample volumes are kept small to facilitate mixing and conserve material.

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“A Doubt Is At Best An Unsafe Standard”: Measuring Sugar In The Early Bureau Of Standards, David Singerman Feb 2007

“A Doubt Is At Best An Unsafe Standard”: Measuring Sugar In The Early Bureau Of Standards, David Singerman

United States Department of Commerce: Staff Publications

In 1900, measuring the purity of sugar was a problem with serious economic consequences, and Congress created the Bureau of Standards in part to create accurate standards for saccharimetry. To direct the Polarimetry Section, Director Stratton hired the young chemist Frederick Bates, who went on to make significant contributions to the discipline of sugar chemistry. This paper explores four of Bates’s greatest accomplishments: identifying the error caused by clarifying lead acetate, inventing the remarkable quartz-compensating saccharimeter with adjustable sensibility, discovering the significant error in the prevailing Ventzke saccharimetric scale, and reviving the International Commission for Uniform Methods of Sugar Analysis …

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Some New Results Of Regular Hadamard Matrices And Sbibd Ii, Tianbing Xia, Mingyuan Xia, Jennifer Seberry Feb 2007

Some New Results Of Regular Hadamard Matrices And Sbibd Ii, Tianbing Xia, Mingyuan Xia, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

In this paper we prove that there exist 4—{k2; ½k(k–1); k(k–2)} SDS, regular Hadamard matrices of order 4k2, and SBIBD (4k2, 2k2 + k, k2 + k) for k = 47, 71, 151, 167, 199, 263, 359, 439, 599, 631, 727, 919, 5q1, 5q2N, 7q3, where q1, q2 and q3 are prime power such that q1 ≡ 1(mod 4), q2 ≡ 5(mod 8) and q …

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Evaluating Climatic And Non-Climatic Influences On Ion Chemistry In Natural And Man-Made Lakes Of Nebraska, Usa, D. M. Bennett, Sherilyn C. Fritz, John C. Holz, Aris A. Holz, Vitaly A. Zlotnik Feb 2007

Evaluating Climatic And Non-Climatic Influences On Ion Chemistry In Natural And Man-Made Lakes Of Nebraska, Usa, D. M. Bennett, Sherilyn C. Fritz, John C. Holz, Aris A. Holz, Vitaly A. Zlotnik

Department of Earth and Atmospheric Sciences: Faculty Publications

Conductivity and major ion chemistry data were analyzed for a suite of Nebraska (USA) natural lakes, reservoirs, sand pits, and barrow pits to evaluate the magnitude of climatic versus non-climatic influence on ionic concentration and composition. In both natural lakes and sand and barrow pits, conductivity is positively related to longitude and reflects decreasing effective moisture from east to west. Reservoirs showed no relationship between lake conductivity and location, probably because the reservoirs are very strongly influenced by groundwater and surface water inflow and have shorter residence times relative to the other lake types. At smaller spatial scales, conductivity among …

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Extinction Pattern Of Reef Ecosystems In Latest Permian, Yasheng Wu, Jiasong Fan, Hongxia Jiang, Wan Yang Feb 2007

Extinction Pattern Of Reef Ecosystems In Latest Permian, Yasheng Wu, Jiasong Fan, Hongxia Jiang, Wan Yang

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Studies of two Permian-Triassic boundary (PTB) sections on top of a Changhsingian reef in Ziyun, Guizhou Province, southwestern China indicate that the end-Permian mass extinction of reef ecosystems occurred in two steps. The first step is the extinction of all stenotropic organisms such as calcisponges and fusulinids in the latest Permian (in the Clarkina yini conodont zone). The biota after the first extinction is simple, comprising eurytropic organisms including microgastropods, ostracods, and some small burrowing organisms, or only algal mats. At the beginning of the Early Triassic (i.e. the beginning of the Hindeodus parvus zone), the environments became anoxic, and …

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Percussive Penetration Of Unconsolidated Granular Media In A Laboratory Setting, Leslie S. Gertsch Feb 2007

Percussive Penetration Of Unconsolidated Granular Media In A Laboratory Setting, Leslie S. Gertsch

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

This controlled study examined the feasibility of a simple percussive approach to drilling through unconsolidated regolith deposits on Mars. The experiments showed that the approach is feasible at the low power levels and low confining pressures used, and that the rate of impact is more important to the penetration rate than is the mass of the impactor (hammer). More massive impactors tend to lower energy efficiency, as they do in terrestrial pile-driving. Unexpectedly, penetration plotted against applied energy tends to cluster into parallel linear trends. Within a given cluster, penetration is very sensitive to applied energy, while between clusters, the …

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The Impact Of Receiver Aperture Design And Telescope Properties On Lidar Signal-To-Noise Ratio Improvements, Yasser Hassebo, Khaled El Sayed Feb 2007

The Impact Of Receiver Aperture Design And Telescope Properties On Lidar Signal-To-Noise Ratio Improvements, Yasser Hassebo, Khaled El Sayed

Publications and Research

Range and sensitivities of lidar measurements in daylight are limited by sky background noise power (BGP). This is particularly important for Raman lidar techniques where the Raman backscattered signal is relatively weak. This often restricts Raman lidar measurements to nighttime where BGP is absent. The background noise elimination is particularly important in daytime measurements in case where full overlap between laser beam and receiver telescope field-of-view (FOV) is necessary. Results of numerical simulations for a vertically pointing Lidar show that significant improvements in Lidar signal to noise ratio (SNR) can be obtained, by minimizing the detected sky BGP. This can …

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Approximations Of Continuous Newton's Method: An Extension Of Cayley's Problem, Jon T. Jacobsen, Owen Lewis '05, Bradley Tennis '06 Feb 2007

Approximations Of Continuous Newton's Method: An Extension Of Cayley's Problem, Jon T. Jacobsen, Owen Lewis '05, Bradley Tennis '06

All HMC Faculty Publications and Research

Continuous Newton's Method refers to a certain dynamical system whose associated flow generically tends to the roots of a given polynomial. An Euler approximation of this system, with step size h=1, yields the discrete Newton's method algorithm for finding roots. In this note we contrast Euler approximations with several different approximations of the continuous ODE system and, using computer experiments, consider their impact on the associated fractal basin boundaries of the roots

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Hubble Space Telescope Ultraviolet Spectroscopy Of 14 Low-Redshift Quasars, Rajib Ganguly, Michael S. Brotherton, Nahum Arav, Sara R. Heap, Lutz Wisotzki, Thomas L. Aldcroft, Danielle Alloin, Ehud Behar, Gabriela Canalizo, D. Michael Crenshaw, Martijn De Kool, Kenneth Chambers, Gerald Cecil, Eleni Chatzichristou, John Everett, Jack R. Gabel, C. Martin Gaskell, Emmanuel Galliano, Richard F. Green, Patrick B. Hall, Dean C. Hines, Vesa T. Junkkarinen, Jelle S. Kaastra, Mary Elizabeth Kaiser, Demosthenes Kazanas, Arieh Konigl, Kirk T. Korista, Gerard A. Kriss, Ari Laor, Karen M. Leighly, Smita Mathur, Patrick Ogle, Daniel Proga, Bassem Sabra, Ran Sivron, Stephanie A. Snedden, Randal Telfer, Marianne Vestergaard Feb 2007

Hubble Space Telescope Ultraviolet Spectroscopy Of 14 Low-Redshift Quasars, Rajib Ganguly, Michael S. Brotherton, Nahum Arav, Sara R. Heap, Lutz Wisotzki, Thomas L. Aldcroft, Danielle Alloin, Ehud Behar, Gabriela Canalizo, D. Michael Crenshaw, Martijn De Kool, Kenneth Chambers, Gerald Cecil, Eleni Chatzichristou, John Everett, Jack R. Gabel, C. Martin Gaskell, Emmanuel Galliano, Richard F. Green, Patrick B. Hall, Dean C. Hines, Vesa T. Junkkarinen, Jelle S. Kaastra, Mary Elizabeth Kaiser, Demosthenes Kazanas, Arieh Konigl, Kirk T. Korista, Gerard A. Kriss, Ari Laor, Karen M. Leighly, Smita Mathur, Patrick Ogle, Daniel Proga, Bassem Sabra, Ran Sivron, Stephanie A. Snedden, Randal Telfer, Marianne Vestergaard

C. Martin Gaskell Publications

We present low-resolution ultraviolet spectra of 14 low-redshift (zem ≤ 0:8) quasars observed with the Hubble Space Telescope STIS as part of a Snapshot project to understand the relationship between quasar outflows and luminosity. By design, all observations cover the C iv emission line. Ten of the quasars are from the Hamburg-ESO catalog, three are from the Palomar-Green catalog, and one is from the Parkes catalog. The sample contains a few interesting quasars, including two broad absorption line (BAL) quasars (HE 0143-3535 and HE 0436-2614), one quasar with a mini-BAL (HE 1105-0746), and one quasar with associated narrow absorption …

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Polyvinylidene Fluoride–Trifluoroethylene As A Reservoir For Absorbed Water, P.A. Jacobson, Luis G. Rosa, Kristin Kraemer, Stephen Ducharme, Peter A. Dowben Feb 2007

Polyvinylidene Fluoride–Trifluoroethylene As A Reservoir For Absorbed Water, P.A. Jacobson, Luis G. Rosa, Kristin Kraemer, Stephen Ducharme, Peter A. Dowben

Peter Dowben Publications

The absorption of water in Langmuir–Blodgett films of ferroelectric copolymers of polyvinylidene fluoride with trifluoroethylene is shown to depend upon the film thickness. This water absorption can have a profound effect on the dielectric properties of the copolymer films.

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Correlation Effects And Electronic Structure Of Gd@C60, Renat F. Sabirianov, Wai-Ning Mei, Jing Lu, Yi Gao, Xiao Cheng Zeng, R. D. Bolskar, P. Jeppson, Ning Wu, A. N. Caruso, Peter A. Dowben Feb 2007

Correlation Effects And Electronic Structure Of Gd@C60, Renat F. Sabirianov, Wai-Ning Mei, Jing Lu, Yi Gao, Xiao Cheng Zeng, R. D. Bolskar, P. Jeppson, Ning Wu, A. N. Caruso, Peter A. Dowben

Peter Dowben Publications

We have investigated the electronic structure of Gd@C60 using ab initio calculations, photoemission and resonant photoemission (constant initial state spectroscopy). In comparing our calculations based on the local spin density approximation and the Hubbard model description with the observed photoemission spectra, we conclude that Gd 4f states exhibit enhanced correlation energies. These correlation energies have values larger than those normally observed in metallic gadolinium and gadolinium compounds. We attributed the enhanced correlation to the diminished screening of the encapsulated Gd. Both calculation and experiment confirm a strong hybridization between the valence states of Gd and the C 2p states …

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The Structure Of The Homunculus. Ii. Modeling The Physical Conditions In Η Carinae's Molecular Shell, Nathan Smith, Gary J. Ferland Feb 2007

The Structure Of The Homunculus. Ii. Modeling The Physical Conditions In Η Carinae's Molecular Shell, Nathan Smith, Gary J. Ferland

Physics and Astronomy Faculty Publications

We present models that reproduce the observed double-shell structure of the Homunculus Nebula around η Carinae, including the stratification of infrared H2 and [Fe II] emission seen in data obtained with the Phoenix spectrograph on Gemini South, as well as the corresponding stratified grain temperature seen in thermal-infrared data. Tuning the model to match the observed shell thickness allows us to determine the threshold density that permits survival of H2. An average density of nH~=(0.5-1)×107 cm-3 in the outer zone is required to allow H2 to exist at all latitudes in the …

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Radiation Trapping In Rubidium Optical Pumping At Low Buffer-Gas Pressures, Mark A. Rosenberry, J. P. Reyes, D. Tupa, Timothy J. Gay Feb 2007

Radiation Trapping In Rubidium Optical Pumping At Low Buffer-Gas Pressures, Mark A. Rosenberry, J. P. Reyes, D. Tupa, Timothy J. Gay

Timothy J. Gay Publications

We have made a systematic study of rubidium optical pumping in a simple cylindrical cell geometry with a high-power 10 W diode laser array, low magnetic fields, and buffer-gas pressures of less than 50 torr. We have determined rubidium polarizations experimentally for H2, N2, He, and Ar buffer gases, with Rb number densities from 1012 to 1013 cm-3. Comparison to a relatively simple optical pumping model allows us to extract useful information about radiation trapping and quenching effects.

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Calculus Students’ Difficulties In Using Variables As Changing Quantities, Susan S. Gray, Barbara J. Loud, Carole Sokolowski Feb 2007

Calculus Students’ Difficulties In Using Variables As Changing Quantities, Susan S. Gray, Barbara J. Loud, Carole Sokolowski

Mathematics Faculty Publications

The study of calculus requires an ability to understand algebraic variables as generalized numbers and as functionally-related quantities. These more advanced uses of variables are indicative of algebraic thinking as opposed to arithmetic thinking. This study reports on entering Calculus I students’ responses to a selection of test questions that required the use of variables in these advanced ways. On average, students’ success rates on these questions were less than 50%. An analysis of errors revealed students’ tendencies toward arithmetic thinking when they attempted to answer questions that required an ability to think of variables as changing quantities, a characteristic …

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A Combinatorial Solution To Intertwined Recurrences, Arthur T. Benjamin, Michael D. Hirschhorn Feb 2007

A Combinatorial Solution To Intertwined Recurrences, Arthur T. Benjamin, Michael D. Hirschhorn

All HMC Faculty Publications and Research

We provide combinatorial derivations of solutions to intertwined second order linear recurrences (such as an = pbn-1 + qan-2, bn = ran-1 + sbn-2) by counting tilings of length n strips with squares and dominoes of various colors and shades. A similar approach can be applied to intertwined third order recurrences with coefficients equal to one. Here we find that all solutions can be expressed in terms of tribonacci numbers. The method can also be easily extended to solve and combinatorially comprehend kth order Fibonacci recurrences.

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Fibonacci Deteminants - A Combinatorial Approach, Arthur T. Benjamin, Naiomi T. Cameron, Jennifer J. Quinn Feb 2007

Fibonacci Deteminants - A Combinatorial Approach, Arthur T. Benjamin, Naiomi T. Cameron, Jennifer J. Quinn

All HMC Faculty Publications and Research

In this paper, we provide combinatorial interpretations for some determinantal identities involving Fibonacci numbers. We use the method due to Lindström-Gessel-Viennot in which we count nonintersecting n-routes in carefully chosen digraphs in order to gain insight into the nature of some well-known determinantal identities while allowing room to generalize and discover new ones.

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The Lsb Theorem Implies The Kkm Lemma, Gwen Spencer '05, Francis E. Su Feb 2007

The Lsb Theorem Implies The Kkm Lemma, Gwen Spencer '05, Francis E. Su

All HMC Faculty Publications and Research

No abstract provided in this article.

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Wmi Outdoor News Bulletin * February 2007, Volume 61, No. 2 Feb 2007

Wmi Outdoor News Bulletin * February 2007, Volume 61, No. 2

Wildlife Management Institute Outdoor News Bulletin

Contents:

• Secretary Kempthorne and Richard Louv to keynote North American Conference

• Elk book again available and at huge discount

• Predator/prey workshop at North American set agenda

• Jaywalking wildlife in Arizona may catch a break

• Proposed plowing of the Farm Bill

• Cooperative Fish and Wildlife Research Unit partners advocate rejecting budget request

• Worth reading:

Backcountry Bear Basics

Scout: The Christmas Dog

A Hunter’s Book of Days

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Interface Effects In Spin-Dependent Tunneling, Evgeny Y. Tsymbal, Kirill D. Belashchenko, Julian P. Velev, Sitaram Jaswal, Mark Van Schilfgaarde, Ivan I. Oleynik, Derek A. Stewart Feb 2007

Interface Effects In Spin-Dependent Tunneling, Evgeny Y. Tsymbal, Kirill D. Belashchenko, Julian P. Velev, Sitaram Jaswal, Mark Van Schilfgaarde, Ivan I. Oleynik, Derek A. Stewart

Evgeny Tsymbal Publications

In the past few years the phenomenon of spin dependent tunneling (SDT) in magnetic tunnel junctions (MTJs) has aroused enormous interest and has developed into a vigorous field of research. The large tunneling magnetoresistance (TMR) observed in MTJs garnered much attention due to possible application in random access memories and magnetic field sensors. This led to a number of fundamental questions regarding the phenomenon of SDT. One such question is the role of interfaces in MTJs and their effect on the spin polarization of the tunneling current and TMR. In this paper we consider different models which suggest that the …

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Lake Whatcom Model Calibration With Variable Stoichiometry In Sediments - Revised, Chris Berger, Scott A. Wells Feb 2007

Lake Whatcom Model Calibration With Variable Stoichiometry In Sediments - Revised, Chris Berger, Scott A. Wells

Civil and Environmental Engineering Faculty Publications and Presentations

This memorandum discusses model calibration and enhancements made to the Lake Whatcom water quality model. Model development and initial calibration were documented in the report “Lake Whatcom Water Quality Model” (Berger and Wells, 2005). The Lake Whatcom water quality model has been converted from CE-QUAL-W2 version 3.2 to version 3.5 (Cole and Wells, 2006).

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Engineering Mathematics Education At Wright State University: Uncorking The First Year Bottleneck, Nathan W. Klingbeil, Kuldip S. Rattan, Michael L. Raymer, David B. Reynolds, Richard Mercer Feb 2007

Engineering Mathematics Education At Wright State University: Uncorking The First Year Bottleneck, Nathan W. Klingbeil, Kuldip S. Rattan, Michael L. Raymer, David B. Reynolds, Richard Mercer

Kno.e.sis Publications

No abstract provided.

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Dental Wash: A Problematic Method For Extracting Microfossils From Teeth (Galley Proofs), Célia H. C. Boyadjian, Sabine Eggers, Karl J. Reinhard Feb 2007

Dental Wash: A Problematic Method For Extracting Microfossils From Teeth (Galley Proofs), Célia H. C. Boyadjian, Sabine Eggers, Karl J. Reinhard

School of Natural Resources: Faculty Publications

A variety of microfossils, originating from plant foods, become trapped in the dental calculus matrix. Processing of dental calculus allows extraction of these microfossils. The resulting data can be used to reconstruct diet at the individual and population levels as the identification of microfossils like starch grains and phytoliths to the generic level, and sometimes to the species level, is possible. However, in some archaeological sites, dental calculus deposits do not preserve well enough to be processed. To prevent the loss of information in such cases, we present a technique, called ‘‘dental wash’’. It permits extracting microfossils from cryptic dental …

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Bioeconomic Analysis Of Herpetofauna Road-Kills In A Florida State Park, Stephanie A. Shwiff, Henry T. Smith, Richard M. Engeman, Robert M. Barry, Robin J. Rossmanith, Mark Nelson Feb 2007

Bioeconomic Analysis Of Herpetofauna Road-Kills In A Florida State Park, Stephanie A. Shwiff, Henry T. Smith, Richard M. Engeman, Robert M. Barry, Robin J. Rossmanith, Mark Nelson

United States Department of Agriculture Wildlife Services: Staff Publications

Road-kills are a major cause of mortality for a wide variety of herpetofauna, but management decisions on remediation procedures for reducing losses are based in economic realities. Because funding is finite for species conservation, bioeconomic analysis can assist in justifying, evaluating, and maximizing returns on conservation expenditures, especially for low-profile species such as herpetofauna. Here, we present a bioeconomic analysis of road-killed herpetofauna in Jonathan Dickinson State Park, Florida. Road surveys were conducted daily for four years to identify and enumerate the numbers of each reptile and amphibian species killed by vehicles. Conservative individual valuations applied to the losses formed …

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Serologic Evidence Of West Nile Virus Exposure In North American Mesopredators, Kevin T. Bentler, Jeffrey S. Hall, J. Jeffrey Root, Kaci Klenk, Brandon S. Schmit, Bradley F. Blackwell, Paul C. Ramey, Larry Clark Feb 2007

Serologic Evidence Of West Nile Virus Exposure In North American Mesopredators, Kevin T. Bentler, Jeffrey S. Hall, J. Jeffrey Root, Kaci Klenk, Brandon S. Schmit, Bradley F. Blackwell, Paul C. Ramey, Larry Clark

United States Department of Agriculture Wildlife Services: Staff Publications

Sera from 936 mammalian mesopredators (Virginia opossums, gray foxes, striped skunks, hooded skunks, raccoons, a bobcat, and a red fox) were collected during 2003 and 2004 in California, Arizona, Texas, Louisiana, Ohio, and Wyoming and screened for flavivirus-specific antibodies by an epitope-blocking enzyme-linked immunosobent assay (blocking ELISA). Serum samples positive for antibodies against flaviviruses were screened for West Nile virus (WNV)– specific antibodies by blocking ELISA and selectively confirmed with plaque-reduction neutralization tests. High prevalence rates were observed in raccoons (45.6%) and striped skunks (62.9%). The high WNV antibody prevalence noted in mesopredators, their peridomestic tendencies, and their overall pervasiveness …

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The Plasminogen-Binding Group A Streptococcal M Protein-Related Protein Prp Binds Plasminogen Via Arginine And Histidine Residues, Martina L. Sanderson-Smith, M. Dowton, Marie Ranson, Mark J. Walker Feb 2007

The Plasminogen-Binding Group A Streptococcal M Protein-Related Protein Prp Binds Plasminogen Via Arginine And Histidine Residues, Martina L. Sanderson-Smith, M. Dowton, Marie Ranson, Mark J. Walker

Faculty of Science - Papers (Archive)

The migration of the human pathogen Streptococcus pyogenes (group A streptococcus) from localized to deep tissue sites may result in severe invasive disease, and sequestration of the host zymogen plasminogen appears crucial for virulence. Here, we describe a novel plasminogen-binding M protein, the plasminogen-binding group A streptococcal M protein (PAM)-related protein (Prp). Prp is phylogenetically distinct from previously described plasminogen-binding M proteins of group A, C, and G streptococci. While competition experiments indicate that Prp binds plasminogen with a lower affinity than PAM (50% effective concentration = 0.34 µM), Prp nonetheless binds plasminogen with high affinity and at physiologically relevant …

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Today's Mathematics Students, Carmen M. Latterell Feb 2007

Today's Mathematics Students, Carmen M. Latterell

The Mathematics Enthusiast

A common mistake that undergraduate mathematics professors make when teaching is to assume that students are younger versions of themselves. Since many mathematics professors are above average in intelligence and were quite good students, the assumption that students are just like themselves can cause pedagogical difficulties (Krantz, 1993). To teach effectively, it is important to understand students. Yet, understanding today's students is literally like bridging a generation gap (Hawk, 2005).

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Lagrange: A Well-Behaved Function, Benjamin Harris Feb 2007

Lagrange: A Well-Behaved Function, Benjamin Harris

The Mathematics Enthusiast

This paper outlines the biography and achievements of Joseph Louis Lagrange (1736–1813) and includes a detailed explanation, with examples, of the Lagrange Multiplier method for optimizing multivariate functions subject to constraint. The Lagrange Multiplier is widely used in chemistry, physics, and economics, in particular. The paper considers the origin of economics’ use of the multiplier and provides a concrete example of how it is used in microeconomic theory. While the focus is on the multiplier’s application to microeconomics, the intended audience includes all teachers and students who encounter any of Lagrange’s contributions. Since Lagrange’s contributions to mathematics are numerous, so …

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Can Our Learners Model In Mathematics?, Vimolan Mudaly Feb 2007

Can Our Learners Model In Mathematics?, Vimolan Mudaly

The Mathematics Enthusiast

Mathematical modeling of real world conditions should be part ofl mathematics classroom activities. In this paper I argue that when real world problems are taught at schools learners are not able to cope on their own, without the assistance of their educator. There is very little or no emphasis placed on this aspect of mathemtics at schools, although it is just beginning to make an appearance in our new Outcomes Based Curriculum. I also discuss an experiment conducted with Grade 10 learners (15 year old) and their responses to real world problems and the conditions that need to be considered. …

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Computation Of Dark Frames In Digital Imagers, Ralf Widenhorn, Armin Rest, Morley M. Blouke, Richard L. Berry, Erik Bodegom Feb 2007

Computation Of Dark Frames In Digital Imagers, Ralf Widenhorn, Armin Rest, Morley M. Blouke, Richard L. Berry, Erik Bodegom

Physics Faculty Publications and Presentations

Dark current is caused by electrons that are thermally exited into the conduction band. These electrons are collected by the well of the CCD and add a false signal to the chip. We will present an algorithm that automatically corrects for dark current. It uses a calibration protocol to characterize the image sensor for different temperatures. For a given exposure time, the dark current of every pixel is characteristic of a specific temperature. The dark current of every pixel can therefore be used as an indicator of the temperature. Hot pixels have the highest signal-to-noise ratio and are the best …

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