9,118 research outputs found

    A Framework to Manage the Complex Organisation of Collaborating: Its Application to Autonomous Systems

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    In this paper we present an analysis of the complexities of large group collaboration and its application to develop detailed requirements for collaboration schema for Autonomous Systems (AS). These requirements flow from our development of a framework for collaboration that provides a basis for designing, supporting and managing complex collaborative systems that can be applied and tested in various real world settings. We present the concepts of "collaborative flow" and "working as one" as descriptive expressions of what good collaborative teamwork can be in such scenarios. The paper considers the application of the framework within different scenarios and discuses the utility of the framework in modelling and supporting collaboration in complex organisational structures

    Late-Summer Abundance and Distribution of Marine Birds in Kasegaluk Lagoon, Chukchi Sea, Alaska

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    Oil and gas drilling programs in the Alaska Chukchi Sea were carried out on leases offshore from Kasegaluk Lagoon in 1989-91, and further exploration and development activities in this area are likely in future years. We conducted aerial surveys between late July and early September 1989-91 to determine the distribution and abundance of marine birds in the Kasegaluk Lagoon area. We hypothesized that Kasegaluk Lagoon supported an avifauna similar to that found in other lagoon systems in arctic Alaska. In fact, the richness and diversity of bird species using Kasegaluk Lagoon were greater than in lagoon systems in the Beaufort Sea. Brant (Branta bernicla) was the most abundant species in Kasegaluk Lagoon compared to lagoons in the Beaufort Sea, where the Oldsquaw (Clangula hyemalis) is the dominant species. Several other species or species groups, such as Glaucous Gull (Larus hyperboreus), Arctic Tern (Sterna Paradisaea), small shorebirds (mainly Calidris and Phalaropus), and Lesser Snow Goose (Chen caerulescens) were also relatively abundant in Kasegaluk Lagoon.Key words: waterbirds, aerial surveys, lagoon ecosystems, Kasegaluk Lagoon, Chukchi Sea, Beaufort Sea, AlaskaDes programmes de forage pétrolier et gazier ont été exécutés dans la portion alaskienne de la mer des Tchouktches, sur des concessions au large de l'étang côtier Kasegaluk de 1989 à 1991, et on prévoit que d'autres activités reliées à l'exploration et au développement auront lieu à cet endroit dans les années à venir. On a effectué des relevés aériens entre la fin de juillet et le début de septembre de 1989 à 1991, afin de déterminer la distribution et l'abondance des oiseaux marins dans la région de l'étang côtier Kasegaluk. On avait émis l'hypothèse que cet étang était le refuge d'une avifaune semblable à celle qui se trouve dans d'autres systèmes lagunaires dans l'Alaska arctique. En réalité, la richesse et la diversité des espèces d'oiseaux utilisant l'étang Kasegaluk étaient supérieures à celles des systèmes lagunaires de la mer de Beaufort. La bernache cravant (Branta bernicla) représentait l'espèce la plus abondante de l'étang côtier Kasegaluk comparé aux étangs côtiers de la mer de Beaufort, où le canard kakawi (Clangula hyemalis) est l'espèce dominante. Plusieurs autres espèces ou groupes d'espèces, comme le goéland bourgmestre (Larus hyperboreus), la sterne arctique (Sterna paradisaea), les petits oiseaux de rivage (surtout Calidris et Phalaropus) et la petite oie blanche (Chen caerulescens) étaient relativement abondants dans l'étang côtier Kasegaluk.Mots clés : oiseaux aquatiques, relevés aériense,écosystèmes lagunaires, étang côtier Kasegaluk, mer des Tchouktches, mer de Beaufort, Alask

    Measurement of the dynamic charge response of materials using low-energy, momentum-resolved electron energy-loss spectroscopy (M-EELS)

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    One of the most fundamental properties of an interacting electron system is its frequency- and wave-vector-dependent density response function, χ(q,ω)\chi({\bf q},\omega). The imaginary part, χ(q,ω)\chi''({\bf q},\omega), defines the fundamental bosonic charge excitations of the system, exhibiting peaks wherever collective modes are present. χ\chi quantifies the electronic compressibility of a material, its response to external fields, its ability to screen charge, and its tendency to form charge density waves. Unfortunately, there has never been a fully momentum-resolved means to measure χ(q,ω)\chi({\bf q},\omega) at the meV energy scale relevant to modern elecronic materials. Here, we demonstrate a way to measure χ\chi with quantitative momentum resolution by applying alignment techniques from x-ray and neutron scattering to surface high-resolution electron energy-loss spectroscopy (HR-EELS). This approach, which we refer to here as "M-EELS," allows direct measurement of χ(q,ω)\chi''({\bf q},\omega) with meV resolution while controlling the momentum with an accuracy better than a percent of a typical Brillouin zone. We apply this technique to finite-q excitations in the optimally-doped high temperature superconductor, Bi2_2Sr2_2CaCu2_2O8+x_{8+x} (Bi2212), which exhibits several phonons potentially relevant to dispersion anomalies observed in ARPES and STM experiments. Our study defines a path to studying the long-sought collective charge modes in quantum materials at the meV scale and with full momentum control.Comment: 26 pages, 10 sections, 7 figures, and an appendi

    Habitat‐related error in estimating temperatures from leaf margins in a humid tropical forest

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142103/1/ajb21096.pd

    Projected seniority-two orbital optimization of the Antisymmetric Product of one-reference orbital Geminal

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    We present a new, non-variational orbital-optimization scheme for the Antisymmetric Product of one-reference orbital Geminal wave function. Our approach is motivated by the observation that an orbital-optimized seniority-zero configuration interaction (CI) expansion yields similar results to an orbital-optimized seniority-zero-plus-two CI expansion [J. Chem. Phys., 135, 044119 (2011)]. A numerical analysis is performed for the C2_2, LiF and CH2_2 molecules as well as for the symmetric stretching of hypothetical (linear) hydrogen chains. For these test cases, the proposed orbital-optimization protocol yields similar results to its variational orbital optimization counterpart, but prevents symmetry-breaking of molecular orbitals in most cases.Comment: 7 pages, 2 figure

    Two Jovian-Mass Planets in Earthlike Orbits

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    We report the discovery of two new planets: a 1.94 M_Jup planet in a 1.8-year orbit of HD 5319, and a 2.51 M_Jup planet in a 1.1-year orbit of HD 75898. The measured eccentricities are 0.12 for HD 5319 b and 0.10 for HD 75898 b, and Markov Chain Monte Carlo simulations based on derived orbital parameters indicate that the radial velocities of both stars are consistent with circular planet orbits. With low eccentricity and 1 < 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.Comment: 32 pages, including 11 figures and 5 tables. Accepted by Ap
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