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Journal ArticleDOI

Phd by thesis

01 Apr 1988-Nature (Nature Publishing Group)-Vol. 332, Iss: 6166, pp 676-676
TL;DR: In this paper, a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) is presented.
Abstract: Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

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Citations
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Dissertation
01 Jan 1994
TL;DR: This thesis introduces reactiveodometric plans and demonstrates their use in plan execution, plan recognition, and learning to associate human terms with perceptually unremarkable locations in the environment.
Abstract: We have developed a system which mediates between an unmodified reactive mobile robot architecture and human natural language I/O. We introduce reactiveodometric plans and demonstrate their use in plan execution, plan recognition, and learning to associate human terms with perceptually unremarkable locations in the environment. The communication component of our architecture supports typewritten natural language discourse with people. It lets users name places either immediately or in relation to other known places, ask questions about the robot’s plans and the spatial relationships of known places, and give the robot short and long term goals. This thesis presents results obtained with our implementation of this architecture on a physical mobile robot system designed by[Connell, 1992a] and in simulation. These results reflect experiments performed by the author and by other users. Thesis Supervisor: Lynn Andrea Stein Title: Class of 1957 Assistant Professor of Computer Science

85 citations


Cites methods from "Phd by thesis"

  • ...Erann Gat developed the ATLANTIS architecture and used it to control a variety of physical and simulated robots performing navigation tasks [Gat, 1991]....

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  • ...Erann Gat [Gat, 1991] implemented and used a simulator for some experiments...

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  • ...The powerful simulator we call for here has its origins in the discussion of better simulators as a future direction Erann Gat’s dissertation [Gat, 1991]....

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Journal ArticleDOI
TL;DR: In this paper, the effects of the realistic stochastic background of perturbations of the so-called concordance model on the combined light-cone and ensemble average of various functions of the luminosity distance, and on their variance, as functions of redshift.
Abstract: Starting from the luminosity-redshift relation recently given up to second order in the Poisson gauge, we calculate the effects of the realistic stochastic background of perturbations of the so-called concordance model on the combined light-cone and ensemble average of various functions of the luminosity distance, and on their variance, as functions of redshift. We apply a gauge-invariant light-cone averaging prescription which is free from infrared and ultraviolet divergences, making our results robust with respect to changes of the corresponding cutoffs. Our main conclusions, in part already anticipated in a recent letter for the case of a perturbation spectrum computed in the linear regime, are that such inhomogeneities not only cannot avoid the need for dark energy, but also cannot prevent, in principle, the determination of its parameters down to an accuracy of order $10^{-3}-10^{-5}$, depending on the averaged observable and on the regime considered for the power spectrum. However, taking into account the appropriate corrections arising in the non-linear regime, we predict an irreducible scatter of the data approaching the 10% level which, for limited statistics, will necessarily limit the attainable precision. The predicted dispersion appears to be in good agreement with current observational estimates of the distance-modulus variance due to Doppler and lensing effects (at low and high redshifts, respectively), and represents a challenge for future precision measurements.

85 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the on-axis mechanical properties of the general forms of the flexing anti-tetrachiral system through analytical and finite element models and showed that these properties are highly dependent on the geometry (the ratio of ligament lengths, thicknesses, and radius of nodes).
Abstract: Chiral systems are a class of structures, which may exhibit the anomalous property of a negative Poisson's ratio. Proposed by Wojciechowski and implemented later by Lakes, these structures have aroused interest due to their remarkable mechanical properties and numerous potential applications. In view of this, this paper investigates the on-axis mechanical properties of the general forms of the flexing anti-tetrachiral system through analytical and finite element models. The results suggest that these are highly dependent on the geometry (the ratio of ligament lengths, thicknesses, and radius of nodes) and material properties of the constituent materials. We also show that the rigidity of an anti-tetrachiral system can be changed without altering the Poisson's ratio. The anti-tetrachiral system, with the unit cell shown in red.

85 citations


Cites background or methods from "Phd by thesis"

  • ...These are only two examples of a larger set of structures, which include the tetrachiral, trichiral, and anti-trichiral systems [12, 13]....

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  • ...This system was dubbed as an “antitetrachiral” honeycomb system by Grima [12, 13]....

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  • ...in accordance with the model derived by Grima [13] for the regular flexing anti-tetrachiral system....

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  • ...This is predicted by the regular flexing model [13]....

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  • ...5) clearly suggest that for all values of a1 and a2 used, the Poisson’s ratio is always negative, although not equal to 1 when a1 61⁄4a2, as predicted for the regular flexing model [13]....

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Journal ArticleDOI
TL;DR: It is shown that such time-asymmetry can alter the relationship between solar cell emission and absorption assumed in the Shockley-Queisser approach, allowing generally accepted photovoltaic performance limits to be exceeded.
Abstract: Limits upon photovoltaic energy conversion efficiency generally are formulated using the detailed balance approach of Shockley and Queisser. One key underlying assumption is invariance upon time reversal, underpinning detailed balance itself. Recent proposals for compact, layered, time-asymmetrical, magneto-optical devices make their routine implementation likely. It is shown that such time-asymmetry can alter the relationship between solar cell emission and absorption assumed in the Shockley-Queisser approach, allowing generally accepted photovoltaic performance limits to be exceeded.

85 citations

Journal ArticleDOI
TL;DR: The current functional and phylogenomic knowledge about type III PKSs are summarized and a new classification of their enzymatic reactions is proposed, which is likely to improve the development of better computational tools for functional prediction of type’s III PKS homologues.
Abstract: Polyketide synthases (PKSs) catalyze the sequential condensation of simple acetate units to produce a large class of natural products, including pharmacologically valuable compounds. PKSs are classified into three types on the basis of their domain structures; type III PKSs have the simplest domain structure, although their products have various structures and functions. The sequence–function relationship is fundamental for predicting enzyme functions, but it has not been well investigated in type III PKSs to date. Consequently, the current methods for predicting type III PKS functions are still immature in comparison with those that target type I/II PKSs. In this review we summarize the current functional and phylogenomic knowledge about type III PKSs and propose a new classification of their enzymatic reactions. We also discuss possible directions for the development of better computational tools for functional prediction of type III PKS homologues.

85 citations

References
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Journal ArticleDOI
TL;DR: A new family of highly fluorescent indicators has been synthesized for biochemical studies of the physiological role of cytosolic free Ca2+ using an 8-coordinate tetracarboxylate chelating site with stilbene chromophores that offer up to 30-fold brighter fluorescence.

21,582 citations


"Phd by thesis" refers background in this paper

  • ...members of this group were produced by Tsien and colleagues [1, 10, 11]....

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  • ...The introduction of Ca 2+ -sensitive fluorescent dyes more than twenty years ago and their permanent improvement [10] enabled investigators to gain unprecedented insights into the mechanisms of cellular signalling....

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ReportDOI
01 Nov 1990
TL;DR: This report will establish methods for performing a domain analysis and describe the products of the domain analysis process to illustrate the application of domain analysis to a representative class of software systems.
Abstract: : Successful Software reuse requires the systematic discovery and exploitation of commonality across related software systems. By examining related software systems and the underlying theory of the class of systems they represent, domain analysis can provide a generic description of the requirements of that class of systems and a set of approaches for their implementation. This report will establish methods for performing a domain analysis and describe the products of the domain analysis process. To illustrate the application of domain analysis to a representative class of software systems, this report will provide a domain analysis of window management system software.

4,420 citations

Journal ArticleDOI
TL;DR: The straw person model (SPM) as mentioned in this paper has been proposed to explain the orientation effects of active galactic nuclei (AGN) and quasars in the line of sight (LOS) images.
Abstract: Because the critical central regions of Active Galactic Nuclei (AGN) and quasars are strongly nonspherical but spatially unresolved, orientation effects have been the source of much confusion. In fact, it now appears that much of the variety in AGN types is just the result of varying orientation relative to the line of sight. We can define an extreme hypothesis,, the straw person model (SPM), in which there are two basic types of AGN: the radio quiets and the radio louds. For each type there is a range in intrinsic luminosity, and the luminosity controls some properties such as the Fanaroff and Riley classes. However, at a given intrinsic luminosity, all other properties such as spectroscopic classification and VLBI component speeds are ascribed to orientation. This model is only a caricature of the unification idea, and is already ruled out on many grounds, but it will be useful for organizing the discussion. I’ll describe what I consider to be convincing evidence that orientation effects are important and widespread. The true situation may be in some sense half way between the SPM and the hypothesis that orientation doesn’t affect classification at aIl. To us optimists, the orienration cup is half full rather than half empty. Although it is too soon to say for sure, the hypothesis that most objects’ classifications would be different if seen from other directions is a tenable one today.

4,005 citations

Journal ArticleDOI
TL;DR: This Review assembles the current knowledge on the isolation of microfibrillated cellulose from wood and its application in nanocomposites; the preparation of nanocrystalline cellulose and its use as a reinforcing agent; and the biofabrication of bacterial nanocellulose, as well as its evaluation as a biomaterial for medical implants.
Abstract: Cellulose fibrils with widths in the nanometer range are nature-based materials with unique and potentially useful features. Most importantly, these novel nanocelluloses open up the strongly expanding fields of sustainable materials and nanocomposites, as well as medical and life-science devices, to the natural polymer cellulose. The nanodimensions of the structural elements result in a high surface area and hence the powerful interaction of these celluloses with surrounding species, such as water, organic and polymeric compounds, nanoparticles, and living cells. This Review assembles the current knowledge on the isolation of microfibrillated cellulose from wood and its application in nanocomposites; the preparation of nanocrystalline cellulose and its use as a reinforcing agent; and the biofabrication of bacterial nanocellulose, as well as its evaluation as a biomaterial for medical implants.

3,452 citations

Journal ArticleDOI
TL;DR: The solid electrolyte interphase (SEI) is a protecting layer formed on the negative electrode of Li-ion batteries as a result of electrolyte decomposition, mainly during the first cycle as discussed by the authors.

2,386 citations