1,014 research outputs found

    New evidence for the age of the Athol Formation (Middle Jurassic : Bajocian) in the Tusk-1 and Tusk-2 wells, offshore Carnarvon Basin, Western Australia

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    The co-occurrence of ammonites with palynomorphs in the Athol Formation of the Tusk-1 and Tusk-2 wells drilled in the offshore Carnarvon Basin, Western Australia confirms the Early Bajocian (Middle Jurassic) age of the Dissiliodinium caddaense dinoflagellate cyst Oppel Zone. The macrofaunas refine this Early Bajocian age to the early Laeviuscula Chronozone. A belemnite from the Tusk-1 well has a strontium isotope (87Sr/86Sr) ratio consistent with the biostratigraphical age. All the identifiable ammonites belong to Pseudotoites robiginosus (Crick). Pseudotoites is prominent in the Early Bajocian of the Indo-Pacific Realm, being known mainly from onshore Western Australia and the Southern Andes, together with rare occurrences in Irian Jaya (west New Guinea); somewhat surprisingly, it is also rarely present in southern Alaska. The palynofloras studied from the Tusk-1 and Tusk-2 wells contain abundant specimens of the marine dinoflagellate cyst Dissiliodinium caddaense, and are assigned to the Dissiliodinium caddaense Oppel Zone. The Athol Formation is a correlative of the Newmarracarra Limestone of the onshore Perth Basin, Western Australia; the distribution of both these units indicates a marine transgression onto the Australian block during the Early Bajocian

    Exact Synchronization for Finite-State Sources

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    We analyze how an observer synchronizes to the internal state of a finite-state information source, using the epsilon-machine causal representation. Here, we treat the case of exact synchronization, when it is possible for the observer to synchronize completely after a finite number of observations. The more difficult case of strictly asymptotic synchronization is treated in a sequel. In both cases, we find that an observer, on average, will synchronize to the source state exponentially fast and that, as a result, the average accuracy in an observer's predictions of the source output approaches its optimal level exponentially fast as well. Additionally, we show here how to analytically calculate the synchronization rate for exact epsilon-machines and provide an efficient polynomial-time algorithm to test epsilon-machines for exactness.Comment: 9 pages, 6 figures; now includes analytical calculation of the synchronization rate; updates and corrections adde

    Scaling in Plasticity-Induced Cell-Boundary Microstructure: Fragmentation and Rotational Diffusion

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    We develop a simple computational model for cell boundary evolution in plastic deformation. We study the cell boundary size distribution and cell boundary misorientation distribution that experimentally have been found to have scaling forms that are largely material independent. The cell division acts as a source term in the misorientation distribution which significantly alters the scaling form, giving it a linear slope at small misorientation angles as observed in the experiments. We compare the results of our simulation to two closely related exactly solvable models which exhibit scaling behavior at late times: (i) fragmentation theory and (ii) a random walk in rotation space with a source term. We find that the scaling exponents in our simulation agree with those of the theories, and that the scaling collapses obey the same equations, but that the shape of the scaling functions depend upon the methods used to measure sizes and to weight averages and histograms

    A Novel Approach to the Common Due-Date Problem on Single and Parallel Machines

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    This paper presents a novel idea for the general case of the Common Due-Date (CDD) scheduling problem. The problem is about scheduling a certain number of jobs on a single or parallel machines where all the jobs possess different processing times but a common due-date. The objective of the problem is to minimize the total penalty incurred due to earliness or tardiness of the job completions. This work presents exact polynomial algorithms for optimizing a given job sequence for single and identical parallel machines with the run-time complexities of O(nlogn)O(n \log n) for both cases, where nn is the number of jobs. Besides, we show that our approach for the parallel machine case is also suitable for non-identical parallel machines. We prove the optimality for the single machine case and the runtime complexities of both. Henceforth, we extend our approach to one particular dynamic case of the CDD and conclude the chapter with our results for the benchmark instances provided in the OR-library.Comment: Book Chapter 22 page

    Quantum phase gate with a selective interaction

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    We present a proposal for implementing quantum phase gates using selective interactions. We analize selectivity and the possibility to implement these gates in two particular systems, namely, trapped ions and Cavity QED.Comment: Four pages of TEX file and two EPS figures. Submitted for publicatio

    Structural Information in Two-Dimensional Patterns: Entropy Convergence and Excess Entropy

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    We develop information-theoretic measures of spatial structure and pattern in more than one dimension. As is well known, the entropy density of a two-dimensional configuration can be efficiently and accurately estimated via a converging sequence of conditional entropies. We show that the manner in which these conditional entropies converge to their asymptotic value serves as a measure of global correlation and structure for spatial systems in any dimension. We compare and contrast entropy-convergence with mutual-information and structure-factor techniques for quantifying and detecting spatial structure.Comment: 11 pages, 5 figures, http://www.santafe.edu/projects/CompMech/papers/2dnnn.htm

    Modeling DNA Structure, Elasticity and Deformations at the Base-pair Level

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    We present a generic model for DNA at the base-pair level. We use a variant of the Gay-Berne potential to represent the stacking energy between neighboring base-pairs. The sugar-phosphate backbones are taken into account by semi-rigid harmonic springs with a non-zero spring length. The competition of these two interactions and the introduction of a simple geometrical constraint leads to a stacked right-handed B-DNA-like conformation. The mapping of the presented model to the Marko-Siggia and the Stack-of-Plates model enables us to optimize the free model parameters so as to reproduce the experimentally known observables such as persistence lengths, mean and mean squared base-pair step parameters. For the optimized model parameters we measured the critical force where the transition from B- to S-DNA occurs to be approximately 140pN140{pN}. We observe an overstretched S-DNA conformation with highly inclined bases that partially preserves the stacking of successive base-pairs.Comment: 15 pages, 25 figures. submitted to PR

    Interjoint Coordination in Kicking a Moving Target: A Comparison Between Elite and Nonelite Taekwondo Players.

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    Patterns of interjoint coordination in the kicking legs of taekwondo players were investigated to understand movement pattern variability as a functional property of skill level. Elite and nonelite players performed roundhouse kicks against a custom-built moving target fitted with an accelerometer, and movements were recorded by motion capture. Average foot segment velocities of 13.6 and 11.4 m/s were recorded for elite and nonelite players, respectively (P < .05), corresponding to target accelerations of 87.5 and 70.8g (P < .05). Gradient values derived from piecewise linear regression of continuous relative phase curves established the comparative incoordination of nonelite taekwondo players in the form of an overshoot behavior during the crucial period leading to target impact (P < .05). This overshoot was apparent in both knee-hip and ankle-knee continuous relative phase curves. Elite players generated greater limb speed and impact force through more effective limb segment coordination. The combination of continuous relative phase and piecewise linear regression techniques allowed identification of alternate joint control approaches in the 2 groups

    Maximizing the entanglement of two mixed qubits

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    Two-qubit states occupy a large and relatively unexplored Hilbert space. Such states can be succinctly characterized by their degree of entanglement and purity. In this letter we investigate entangled mixed states and present a class of states that have the maximum amount of entanglement for a given linear entropy.Comment: 4 pages, 3 figure
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