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2007

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Articles 4831 - 4860 of 6758

Full-Text Articles in Physical Sciences and Mathematics

Characteristics And Error Estimation Of Stratospheric Ozone And Ozone-Related Species Over Poker Flat (65°N, 147°W), Alaska Observed By A Ground-Based Ftir Spectrometer From 2001-2003, A. Kagawa, Y. Kasai, Nicholas Jones, M. Yamamori, K. Seki, F. Murcray, Y. Murayama, K. Mizutani, T. Itabe Jan 2007

Characteristics And Error Estimation Of Stratospheric Ozone And Ozone-Related Species Over Poker Flat (65°N, 147°W), Alaska Observed By A Ground-Based Ftir Spectrometer From 2001-2003, A. Kagawa, Y. Kasai, Nicholas Jones, M. Yamamori, K. Seki, F. Murcray, Y. Murayama, K. Mizutani, T. Itabe

Faculty of Science - Papers (Archive)

It is important to obtain the year-to-year trend of stratospheric minor species in the context of global changes. An important example is the trend in global ozone depletion. The purpose of this paper is to report the accuracy and precision of measurements of stratospheric chemical species that are made at our Poker Flat site in Alaska (65◦ N, 147◦ W). Since 1999, minor atmospheric molecules have been observed using a Fourier-Transform solar-absorption infrared Spectrometer (FTS) at Poker Flat. Vertical profiles of the abundances of ozone, HNO3, HCl, and HF for the period from 2001 to 2003 were retrieved from FTS …

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Mechanochemical Coupling In The Myosin Motor Domain. I. Insights From Equilibrium Active-Site Simulations, Haibo Yu, Liang Ma, Yang Yang, Qiang Cui Jan 2007

Mechanochemical Coupling In The Myosin Motor Domain. I. Insights From Equilibrium Active-Site Simulations, Haibo Yu, Liang Ma, Yang Yang, Qiang Cui

Faculty of Science - Papers (Archive)

Although the major structural transitions in molecular motors are often argued to couple to the binding of Adenosine triphosphate (ATP), the recovery stroke in the conventional myosin has been shown to be dependent on the hydrolysis of ATP. To obtain a clearer mechanistic picture for such ‘‘mechanochemical coupling’’ in myosin, equilibrium active-site simulations with explicit solvent have been carried out to probe the behavior of the motor domain as functions of the nucleotide chemical state and conformation of the converter/relay helix. In conjunction with previous studies of ATP hydrolysis with different active-site conformations and normal mode analysis of structural flexibility, …

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Free Fatty Acids From The Crude Hexane Extract Of The Aerial Parts Of Heliotropium Indicum Linn. Growing In Phitsanulok, Thailand, Theeraphan Machan, Jurgen Korth, Boonsom Liawruangrath, Saisunee Liawruangrath, Apiwat Baramee, Stephen G. Pyne Jan 2007

Free Fatty Acids From The Crude Hexane Extract Of The Aerial Parts Of Heliotropium Indicum Linn. Growing In Phitsanulok, Thailand, Theeraphan Machan, Jurgen Korth, Boonsom Liawruangrath, Saisunee Liawruangrath, Apiwat Baramee, Stephen G. Pyne

Faculty of Science - Papers (Archive)

Sixteen free fatty acids from the crude hexane extract of the aerial parts of Heliotropium indicum Linn. growing in Phitsanulok, Thailand, have been identified after conversion to their methyl esters with boron trifluoride-methanol followed by quantification by GC-FID and identification by GC-MS analysis. They accounted for 95% of the chromatographable components, with 9,12-octadecadienoic acid, (39.7%), 9-octadecenoic acid (32.4%), hexadecanoic acid (14.2%) and octadecanoic acid (5.1%), as the major constituents. A small amount of 6,10,14-trimethyl-2-pentadecanone and 3,7,11,15-tetramethyl-2-hexadecen-1-ol as well as a homologous series of n-alkanes present at trace level and ranging from C25 to C31 was also found …

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Sensitivity Of Marine Microalgae To Copper: The Effect Of Biotic Factors On Copper Adsorption And Toxicity, Jacqueline Levy, Jenny L. Stauber, Dianne F. Jolley Jan 2007

Sensitivity Of Marine Microalgae To Copper: The Effect Of Biotic Factors On Copper Adsorption And Toxicity, Jacqueline Levy, Jenny L. Stauber, Dianne F. Jolley

Faculty of Science - Papers (Archive)

Microalgae are sensitive indicators of environmental change and, as the basis of most freshwater and marine ecosystems, are widely used in the assessment of risk and development of environmental regulations for metals. However, interspecies differences in sensitivity to metals are not well understood. The relationship between metal-algal cell binding and copper sensitivity of marine microalgae was investigated using a series of 72-h growth-rate inhibition bioassays and short-term (1-h) uptake studies. A range of marine algae from different taxonomic groups were screened to determine whether copper adsorption to the cell membrane was influenced by biotic factors, such as the ultrastructure of …

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Some Approaches To New Antibacterial Agents, John B. Bremner Jan 2007

Some Approaches To New Antibacterial Agents, John B. Bremner

Faculty of Science - Papers (Archive)

Bacteria use a number of resistance mechanisms to counter the antibacterial challenge, and one of these is the expression of transmembrane protein-based efflux pumps which can pump out antibacterials from within the cells, thus lowering the antibacterial concentration to nonlethal levels. For example, in S. aureus, the NorA pump can pump out the antibacterial alkaloid berberine and ciprofloxacin. One general strategy to reduce the health threat of resistant bacteria is to block a major bacterial resistance mechanism at the same time as interfering with another bacterial pathway or target site. New developments of this approach in the context of dual-action …

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Incremental Accretion Of A Sandy Reef Island Over The Past 3000 Years Indicated By Component-Specific Radiocarbon Dating, Colin D. Woodroffe, Bongkoch Samosorn, Q Hua, Deirdre E. Hart Jan 2007

Incremental Accretion Of A Sandy Reef Island Over The Past 3000 Years Indicated By Component-Specific Radiocarbon Dating, Colin D. Woodroffe, Bongkoch Samosorn, Q Hua, Deirdre E. Hart

Faculty of Science - Papers (Archive)

Low-lying reef islands appear particularly threatened by anticipated sea-level rise, and determining how they formed and whether they are continuing to accumulate sediment is essential for their sustainable management. Depositional chronology of Warraber Island, a small sand cay in Torres Strait, Australia, is re-examined based on AMS radiocarbon dating of specific skeletal components. Whereas radiometric dating of bulk sand samples indicated one or more discrete phases of mid-late Holocene deposition, component-specific AMS radiocarbon dating of sand grains indicates sustained incremental growth over the past 3000 years. Ages on gastropods that lived on the reef flat around the island indicate continuing …

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Stratomesospheric Co Measured By A Ground-Based Fourier Transform Spectrometer Over Poker Flat, Alaska: Comparisons With Odin/Smr And A 2-D Model, Nicholas B. Jones, Y Kasai, E Dupuy, Y. Murayama, J Urban, B Barret, M Sinnhuber, A. Kagawa, T. Koshiro, P Ricaud, D Murtagh Jan 2007

Stratomesospheric Co Measured By A Ground-Based Fourier Transform Spectrometer Over Poker Flat, Alaska: Comparisons With Odin/Smr And A 2-D Model, Nicholas B. Jones, Y Kasai, E Dupuy, Y. Murayama, J Urban, B Barret, M Sinnhuber, A. Kagawa, T. Koshiro, P Ricaud, D Murtagh

Faculty of Science - Papers (Archive)

The interseasonal variability of stratomesospheric CO is reported from Poker Flat, Alaska, using spectra from a ground-based Fourier Transform Spectrometer (gb-FTS) for the time period from 2000 to 2004. The CO spectra were analyzed using an optimal estimation technique that separates the tropospheric and stratospheric/mesospheric components into partial columns. The distribution of CO in the polar winter is such that the gb-FTS retrieved partial column is weighted to the mesosphere. The gb-FTS data are compared with measurements of partial column CO from the Sub-Millimeter Radiometer on board the Odin satellite and shown to be in very good agreement despite the …

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An Example Of A Hierarchical System Model Using Seam And Its Formalization In Alloy, Alain Wegmann, Lam-Son Le, Jose Diego De La Cruz, Irina Rychkova, Gil Regev Jan 2007

An Example Of A Hierarchical System Model Using Seam And Its Formalization In Alloy, Alain Wegmann, Lam-Son Le, Jose Diego De La Cruz, Irina Rychkova, Gil Regev

Faculty of Informatics - Papers (Archive)

SEAM is an enterprise architecture method based on RM-ODP part 2. In this paper, we present an example of a SEAM hierarchical model where the behavioral part is formalized in Alloy. We introduce four kinds of actions and their relationships to properties that specify object state. We show that the Alloy formalization enables us to check that the SEAM model conforms to the required aspects of the universe of discourse.

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From Business To It With Seam: The J2ee Pet Store Example, Irina Rychkova, Gil Regev, Lam-Son Le, Alain Wegmann Jan 2007

From Business To It With Seam: The J2ee Pet Store Example, Irina Rychkova, Gil Regev, Lam-Son Le, Alain Wegmann

Faculty of Informatics - Papers (Archive)

Business and IT alignment demands clear traceability between the applications to be developed and the business requirements. SEAM is a systemic visual approach for modeling systems, including information systems and organizations. This paper illustrates how we represent the business role of an IT application and its platform-specific realization in SEAM. We use the Java Pet Store sample application as an example.

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Classifying Still Faces With Ultrasonic Sensing, Phillip J. Mckerrow, K. K. Yoong Jan 2007

Classifying Still Faces With Ultrasonic Sensing, Phillip J. Mckerrow, K. K. Yoong

Faculty of Informatics - Papers (Archive)

The echo of a chirp of ultrasonic energy from an object contains information about the geometry of that object: relative depth of surfaces and approximate area of those surfaces. A human face has complex geometry that produces a distinctive echo. In this paper, we report initial research into whether there is sufficient information in the echo to recognize a still face. Potential features for classification are identified using a facial model. The classification results for 10 faces encourage future research with a larger number of faces and with moving faces.

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A Simple Orthogonal Space-Time-Polarization Block Code, Beata J. Wysocki, Tadeusz A. Wysocki, Jennifer R. Seberry, Sarah S. Adams, Hamid Sharif Jan 2007

A Simple Orthogonal Space-Time-Polarization Block Code, Beata J. Wysocki, Tadeusz A. Wysocki, Jennifer R. Seberry, Sarah S. Adams, Hamid Sharif

Faculty of Informatics - Papers (Archive)

This letter proposes a simple but highly efficient technique to jointly utilize space, time, and polarization diversities. The technique is based on extending orthogonal space-time block codes into the quaternion domain and utilizing a description of the dual-polarized signal by means of quaternions, which are a generalization of complex numbers. In the given example, the achievable performance gain for two transmit and one receive antennas is approximately 6 dB at a bit error rate of 10-4 when compared with the Alamouti code.

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A Simple Spatial Model For Self-Heating Compost Piles, Harvinder Sidhu, Mark Nelson, Xiao Dong Chen Jan 2007

A Simple Spatial Model For Self-Heating Compost Piles, Harvinder Sidhu, Mark Nelson, Xiao Dong Chen

Faculty of Informatics - Papers (Archive)

We model the increase in temperature in compost piles due to micro-organisms undergoing exothermic reactions. The model incorporates two types of heat release: one due to biological activity; and the other due to the oxidation of cellulosic materials. In this study we also include the consumption of oxygen. We investigate the bifurcation behaviour and compare the results obtained from models that include and exclude oxygen consumption in both one- and two-dimensional geometries.

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Encapsulation Of C60 Fullerenes Into Single-Walled Carbon Nanotubes: Fundamental Mechanical Principles And Conventional Applied Mathematical Modeling, Duangkamon Baowan, Ngamta Thamwattana, James M. Hill Jan 2007

Encapsulation Of C60 Fullerenes Into Single-Walled Carbon Nanotubes: Fundamental Mechanical Principles And Conventional Applied Mathematical Modeling, Duangkamon Baowan, Ngamta Thamwattana, James M. Hill

Faculty of Informatics - Papers (Archive)

A well-known self-assembled hybrid carbon nanostructure is a nanopeapod which may be regarded as the prototype nanocarrier for drug delivery. While the investigation of the packing of C60 molecules inside a carbon nanotube is usually achieved through either experimentation or large scale computation, this paper adopts elementary mechanical principles and classical applied mathematical modeling techniques to formulate explicit analytical criteria and ideal model behavior for such encapsulation. In particular, we employ the Lennard-Jones potential and the continuum approximation to determine three encapsulation mechanisms for a C60 fullerene entering a tube: (i) through the tube open end (head-on), (ii) around the …

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Mechanics Of Spheroidal Fullerenes And Carbon Nanotubes For Drug And Gene Delivery, Barry Cox, Ngamta Thamwattana, James M. Hill Jan 2007

Mechanics Of Spheroidal Fullerenes And Carbon Nanotubes For Drug And Gene Delivery, Barry Cox, Ngamta Thamwattana, James M. Hill

Faculty of Informatics - Papers (Archive)

There is considerable interest in the mechanics of carbon nanostructures, such as carbon nanotubes and fullerenes , and the manner of their interactions at the intennolecular level. Medical applications i.n clud e the use of carbon .nanotub e. for tar etcd drug a nd gen e delivery, for which issues relating to ll1c acceptan ce and containmen t of dru g or genes are n ot prop ­ erly understood . A sph eroid is an ellipsoid with rwo equal axes and the general spheroidal shape inclu des a wide vadcty of possible m olecu lar onfigurations su ch a …

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Multi-Variable Relationships In A Batch Annealing Process, David J. Scott, Ken Russell, Judi Scheffer Jan 2007

Multi-Variable Relationships In A Batch Annealing Process, David J. Scott, Ken Russell, Judi Scheffer

Faculty of Informatics - Papers (Archive)

Empirical models are developed to predict the mechanical properties of four groups of cold-rolled annealed steels, based on upstream processing variables in the hot-rolling process, annealing conditions, the chemical composition of the steel and product details. Various linear models are considered but the simplest approach of using a multiple linear regression model is considered the most satisfactory. This analytical tool will allow better understanding of the steel making process and the ability to vary input parameters to improve the product. In particular the number of coils which fail mechanical testing may be able to be reduced, with a subsequent fall …

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Design Principles For Low Latency Anonymous Network Systems Secure Against Timing Attacks, Rungrat Wiangsripanawan, Willy Susilo, Reihaneh Safavi-Naini Jan 2007

Design Principles For Low Latency Anonymous Network Systems Secure Against Timing Attacks, Rungrat Wiangsripanawan, Willy Susilo, Reihaneh Safavi-Naini

Faculty of Informatics - Papers (Archive)

Low latency anonymous network systems, such as Tor, were considered secure against timing attacks when the threat model does not include a global ad- versary. In this threat model the adversary can only see part of the links in the system. In a recent paper entitled Low-cost traffic analysis of Tor, it was shown that a variant of timing attack that does not require a global adversary can be applied to Tor. More impor- tantly, authors claimed that their attack would work on any low latency anonymous network systems. The implication of the attack is that all low latency …

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Mitigating Phishing By A New Id-Based Chameleon Hash Without Key Exposure, Qiong Ren, Yi Mu, Willy Susilo Jan 2007

Mitigating Phishing By A New Id-Based Chameleon Hash Without Key Exposure, Qiong Ren, Yi Mu, Willy Susilo

Faculty of Informatics - Papers (Archive)

Chameleon signatures were introduced by Krawczyk and Rabin to provide a non-transferable signature scheme. However, the nontransferability property requires the willingness of the recipient in consequentially exposing a secret key and therefore invalidating all signatures issued to the same recipient’s public key. This notion has been extended by Chen et al. to allow a “key-exposure ” freeness scheme. However, it was concluded that to achieve this key-exposure freeness, one would require a technique called “identity customization”. Therefore, the notion of identity-based chameleon hash function becomes redundant since the identity is always needed in the construction of chameleon hash functions themselves. …

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A New Image Feature For Fast Detection Of People In Images, Son Lam Phung, Abdesselam Bouzerdoum Jan 2007

A New Image Feature For Fast Detection Of People In Images, Son Lam Phung, Abdesselam Bouzerdoum

Faculty of Informatics - Papers (Archive)

In this paper, we present a new method of detecting visual objects in digital images and video. The novelty of the proposed method is that it differentiates objects from non-objects using image edge characteristics. Our approach is based on a fast object detection method recently developed by Viola and Jones. While Viola and Jones use Harr-like features, we propose a new image feature called edge density that can be computed more efficiently. When applied to the problem of detecting people and pedestrians in images, the new feature shows very good discriminative capability compared to Harr-like features.

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Simplicity Of C*-Algebras Associated To Higher-Rank Graphs, David Robertson, Aidan Sims Jan 2007

Simplicity Of C*-Algebras Associated To Higher-Rank Graphs, David Robertson, Aidan Sims

Faculty of Informatics - Papers (Archive)

We prove that if ᴧ is a row-fiuit e k-graph with no sources, then the associated C*-algebra is simple if and only if ᴧ is cofinal and satisfies Kumjian and Pask's aperiodicity condition, known as Condition (A). We prove that the aperiodicity condition is equivalent to a suitably modifi ed version of Robertson and Steger's original nonperiodicity condition (H3), which in particular involves only finite paths. We also characterise both cofinality and aperiodicity of ᴧ in terms of ideals in C* (ᴧ).

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An Ontology-Based Knowledge Network To Reuse Inter-Organizational Knowledge, Nelson K. Y. Leung, Sim Kim Lau, Joshua P. Fan Jan 2007

An Ontology-Based Knowledge Network To Reuse Inter-Organizational Knowledge, Nelson K. Y. Leung, Sim Kim Lau, Joshua P. Fan

Faculty of Informatics - Papers (Archive)

Researchers have developed various types of Knowledge Management approaches that only focus on managing organizational knowledge. However, these designs are inadequate because employees are often needed to access knowledge from other knowledge sources in order to complete their works. Therefore, a new interorganizational Knowledge Management practice is required to enhance the sharing of knowledge across organizational boundaries in their business networks. In this paper, we investigate the application of ontology mediation that provides mechanisms of reconciling inter-organizational knowledge. An ontology-based Interorganizational knowledge Network that incorporates ontology mediation is developed so that heterogeneity of knowledge semantic in the ontologies could be …

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Modelling And Comparative Performance Analysis Of A Time Reversed Uwb System, Keni Popovski, Beata J. Wysocki, Tadeusz A. Wysocki Jan 2007

Modelling And Comparative Performance Analysis Of A Time Reversed Uwb System, Keni Popovski, Beata J. Wysocki, Tadeusz A. Wysocki

Faculty of Informatics - Papers (Archive)

The effects of multipath propagation lead to a significant decrease in system performance in most of the proposed ultra-wideband communication systems. A time-reversed system utilises the multipath channel impulse response to decrease receiver complexity, through a prefiltering at the transmitter. This paper discusses the modelling and comparative performance of a UWB system utilising time-reversed communications. System equations are presented, together with a semianalytical formulation on the level of intersymbol interference and multiuser interference. The standardised IEEE 802.15.3a channel model is applied, and the estimated error performance is compared through simulation with the performance of both time-hopped time-reversed and RAKE-based UWB …

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A New Approach To Bsofdm - Parallel Concatenated Spreading Matrices Ofdm, Ibrahim S. Raad, X. Huang Jan 2007

A New Approach To Bsofdm - Parallel Concatenated Spreading Matrices Ofdm, Ibrahim S. Raad, X. Huang

Faculty of Informatics - Papers (Archive)

This paper proposes a new approach to block spread OFDM called parallel concatenated spreading matrices OFDM (PCSM-OFDM). While BSOFDM improved the overall BER performance on OFDM in frequency selective channels, this new approach further improves the BER of BSOFDM by a 3 dB gain. This is achieved through increasing the diversity of the transmitted samples by concatenating two spreading matrices in parallel to BSOFDM.

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Time Delay Estimation Of Reverberant Meeting Speech: On The Use Of Multichannel Linear Prediction, Eva Cheng, I. Burnett, Christian Ritz Jan 2007

Time Delay Estimation Of Reverberant Meeting Speech: On The Use Of Multichannel Linear Prediction, Eva Cheng, I. Burnett, Christian Ritz

Faculty of Informatics - Papers (Archive)

Effective and efficient access to multiparty meeting recordings requires techniques for meeting analysis and indexing. Since meeting participants are generally stationary, speaker location information may be used to identify meeting events e.g., detect speaker changes. Time-delay estimation (TDE) utilizing cross-correlation of multichannel speech recordings is a common approach for deriving speech source location information. Research improved TDE by calculating TDE from linear prediction (LP) residual signals obtained from LP analysis on each individual speech channel. This paper investigates the use of LP residuals for speech TDE, where the residuals are obtained from jointly modeling the multiple speech channels. Experiments conducted …

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Removing Long-Term Errors From The Avhrr–Based Brightness Temperature (Bt), Md Zahidur Rahman, Leonid Roytman, Felix Kogan Jan 2007

Removing Long-Term Errors From The Avhrr–Based Brightness Temperature (Bt), Md Zahidur Rahman, Leonid Roytman, Felix Kogan

Publications and Research

Empirical distribution functions were applied for removing long-term errors from BT data derived from AVHRR sensor on NOAA environmental satellites. This paper investigates BT stability in the NOAA/NESDIS Global Vegetation Index (GVI) data set during 1982-2003. This period includes five NOAA satellites. Degradation of BT over time for each satellite was estimated for geographical location in China. The method of matching empirical distribution function (EDF) improves the time relative stability of BT data for all satellites, especially NOAA-9, -11 and -14.

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Incompressible And Compressible Boundary Layers On A Fibre In The Melt Spinning Process, John Harding Jan 2007

Incompressible And Compressible Boundary Layers On A Fibre In The Melt Spinning Process, John Harding

Doctoral

This thesis seeks to investigate shear stress on and heat transfer from the surface of a fibre in the industrial process of melt spinning. Melt spinning is the process whereby molten polymer materials are extruded through the holes of a device known as a spinneret to create continuous filaments of polymer. Fibres manufactured in this way are used in applications as diverse as fashion and clothing, to telecommunications. The magnitude ofthe shear stress on the fibre surface, and also the rate of heat transfer from the fibre to the surrounding environment are of major importance to the overall quality of …

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Paleosalinity History Of Middle Holocene Lagoonal And Lacustrine Deposits In The Enriquillo Valley, Dominican Republic Based On Pore Morphometrics And Isotope Geochemistry Of Ostracoda, Pamela Medley, Neil E. Tibert, William P. Patterson, H. Allen Curran, Lisa Greer, Jean-Paul Colin Jan 2007

Paleosalinity History Of Middle Holocene Lagoonal And Lacustrine Deposits In The Enriquillo Valley, Dominican Republic Based On Pore Morphometrics And Isotope Geochemistry Of Ostracoda, Pamela Medley, Neil E. Tibert, William P. Patterson, H. Allen Curran, Lisa Greer, Jean-Paul Colin

Geosciences: Faculty Publications

The southwestern region of the Dominican Republic (Enriquillo Valley) contains exceptionally well-preserved, relict marine and saline lake deposits of mid-Holocne age. Abundant euryhaline ostracodes found in this deposit include Cyprideis salebrosa, C. mexicana, C. similis, and C. edentata. Morphometric and geochemical analyses performed on Cyprideis spp. provide high δ18O and δ13C values that are coincident with relative abundances of irregularly shaped pores that permeate the ostracode carapace. We recognize three stratigraphic intervals with distinct ostracode pore shape and stable isotope trends: (I) a 4.5-5.0m interval that contains ostracodes with highly irregular shaped pores (multiradiate) and …

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Symmetry And Specializability In The Continued Fraction Expansions Of Some Infinite Products, James Mclaughlin Jan 2007

Symmetry And Specializability In The Continued Fraction Expansions Of Some Infinite Products, James Mclaughlin

Mathematics Faculty Publications

Let f(x) ∈ Z[x]. Set f0(x) = x and, for n ≥ 1, define fn(x) = f(fn−1(x)). We describe several infinite families of polynomials for which the infinite product Y∞ n=0 ( 1 + 1 fn(x) ) has a specializable continued fraction expansion of the form S∞ = [1; a1(x), a2(x), a3(x), . . . ], where ai(x) ∈ Z[x] for i ≥ 1. When the infinite product and the continued fraction are specialized by letting x take integral values, we get infinite classes of real numbers whose regular continued fraction expansion is predictable. We also show that, under some …

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Some More Long Continued Fractions, I, James Mclaughlin, Peter Zimmer Jan 2007

Some More Long Continued Fractions, I, James Mclaughlin, Peter Zimmer

Mathematics Faculty Publications

In this paper we show how to construct several infinite families of polynomials D(¯x, k), such that p D(¯x, k) has a regular continued fraction expansion with arbitrarily long period, the length of this period being controlled by the positive integer parameter k. We also describe how to quickly compute the fundamental units in the corresponding real quadratic fields.

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Some Properties Of The Distribution Of The Numbers Of Points On Elliptic Curves Over A Finite Prime Field, Saiying He, James Mclaughlin Jan 2007

Some Properties Of The Distribution Of The Numbers Of Points On Elliptic Curves Over A Finite Prime Field, Saiying He, James Mclaughlin

Mathematics Faculty Publications

Let p ≥ 5 be a prime and for a, b ∈ Fp, let Ea,b denote the elliptic curve over Fp with equation y 2 = x 3 + a x + b. As usual define the trace of Frobenius ap, a, b by #Ea,b(Fp) = p + 1 − ap, a, b. We use elementary facts about exponential sums and known results about binary quadratic forms over finite fields to evaluate the sums P t∈Fp ap, t, b, P t∈Fp ap, a, t, Pp−1 t=0 a 2 p, t, b, Pp−1 t=0 a 2 p, a, t and Pp−1 …

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A Test Of The Cross-Scale Resilience Model: Functional Richness In Mediterranean-Climate Ecosystems, Donald A. Wardwell, Craig R. Allen, Garry D. Peterson, Andrew J. Tyre Jan 2007

A Test Of The Cross-Scale Resilience Model: Functional Richness In Mediterranean-Climate Ecosystems, Donald A. Wardwell, Craig R. Allen, Garry D. Peterson, Andrew J. Tyre

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

Ecological resilience has been proposed to be generated, in part, in the discontinuous structure of complex systems. Environmental discontinuities are reflected in discontinuous, aggregated animal body mass distributions. Diversity of functional groups within body mass aggregations (scales) and redundancy of functional groups across body mass aggregations (scales) has been proposed to increase resilience. We evaluate that proposition by analyzing mammalian and avian communities of Mediterranean-climate ecosystems. We first determined that body mass distributions for each animal community were discontinuous. We then calculated the variance in richness of function across aggregations in each community, and compared observed values with distributions created …

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