102,761 research outputs found
Wulff Steiner polynomial for ovaloid
No full textThe equilibrium shape of a crystal is the celebrated Wulff shape W, which can be obtained via the Wulff flow. When the initial crystal K is convex, the image under the Wulff flow is K + tW after time t. The n + 1-dimensional volume Vn+1(K + tB) is the well known Steiner polynomial , where B is the closed unit ball.Wulff flow and Wulff shape has been highly studied in crystal growth. Ge-ometric information encoded in the the associated Wulff-Steiner polynomial was far from being thoroughly understood.In this thesis, Wulff-Steiner polynomial of degree 2 was surveyed. We ob-tained a characterization of them. The relative positions among the roots , the W-inradius, W-outradius and other geometric quantities are studied. Wulff-Steiner polynomial have no positive real root by its definition. For degree 2, the fact that it must have negative real roots is equivalent to the classi-cal isoperimetric inequality. For degree 3, we showed that complex roots can occur and that the real parts of any complex root must be negative. As an application of the Wulff-Steiner polynomial, we found an invariant under the Wulff flow in any dimension n ≥ 2.</p
El uso del software HistCite para identificar artículos significativos en búsquedas por materias en la Web of Science
No full textHistCiteTM is a large-scale computer tool for mapping science. Its power of visualization combines
the production of historiographs on the basis of the analysis of co-citations of documents, with the
use of bibliometrics specific indicators. The objective of this article is, to present the advantages of
the new bibliometrics configuration of HistCiteTM (2004) when identifying articles to analyze the
histograms that produces HistCiteTM, in terms of cumulative advantage and aging of the citations
to do a comparative study of the results of HistCiteTM, in its indicators of amplitude and recognition.
Also is examined its treatment of the sampling problems, by formalizing the question of
Kendall
Revealing Physical and Ecological Dynamics at an Ice Edge – a Robotic Approach
No full textRevealing Physical and Ecological Dynamics at an Ice Edge – a Robotic Approach
Wulff, T. (1) ; Lehmenhecker, S. (1) ; Hagemann, J. (1) ; Busack, M. (1) ; Tippenhauer, S. (1) ; Strohmeier, M. (2) ; Rothe, J. (2)
1: Alfred Wegener Institute, Bremerhaven, Germany
2: University of Wuerzburg, Wuerzburg, Germany
Marginal ice zones (MIZs) are characterized by the complex and dynamic interaction between the atmosphere, the ice, and the ocean. This high dynamics put MIZs among the – biologically – most productive regions of our planet and make them an ideal place to investigate the coupling between physics and ecology. Fostered by the last decades´ technological progress in robotics and sensor technology, marine sciences are increasingly able to monitor and understand these processes, which occur on very small scales – both temporal and spatial.
The German Alfred Wegener Institute (AWI) has regularly operated an Autonomous Underwater Vehicle (AUV) in the Arctic and especially in the MIZ of the Fram Strait since 2009. Starting in 2011 / 2012 AWI has also used Unmanned Aerial Vehicles (UAVs) to support AUV operations and gather a holistic picture of the investigated area. In our talk we will give an overview on the equipment and infrastructure used to support our AUV dives including an UAV for operations at high latitudes. We will present technical details of our vehicle´s scientific payload which is specifically designed to investigate the physical dynamics of the marginal ice zone and its ecological response
All-Pairs Minimum Cuts in Near-Linear Time for Surface-Embedded Graphs
No full textFor an undirected n-vertex graph G with non-negative edge-weights, we consider the following type of query: given two vertices s and t in G, what is the weight of a minimum st-cut in G? We solve this problem in preprocessing time O(n log^3 n) for graphs of bounded genus, giving the first sub-quadratic time algorithm for this class of graphs. Our result also improves by a logarithmic factor a previous algorithm by Borradaile, Sankowski and Wulff-Nilsen (FOCS 2010) that applied only to planar graphs. Our algorithm constructs a Gomory-Hu tree for the given graph, providing a data structure with space O(n) that can answer minimum-cut queries in constant time. The dependence on the genus of the input graph in our preprocessing time is 2^{O(g^2)}
Letter, [Author unclear] to Paulina T. Merritt
No full textHandwritten letter to Paulina Merritt from an unknown author, October 1, 1876.
memnet: Network Tools for Memory Research
No full textEfficient implementations of network science tools to facilitate research into human (semantic) memory. In its current version, the package contains several methods to infer networks from verbal fluency data, various network growth models, diverse (switcher-) random walk processes, and tools to analyze and visualize networks. To deliver maximum performance the majority of the code is written in C++. For an application see: Wulff, D. U., Hills, T., & Mata, R. (2018) doi:10.31234/osf.io/s73dp>.</p
Unveiling the timescale of the R-T transition in human hemoglobin
No full textTime-resolved wide-angle X-ray scattering, a recently developed technique allowing to probe global structural changes of proteins in solution, was used to investigate the kinetics of R–T quaternary transition in human hemoglobin and to systematically compare it to that obtained with time-resolved optical spectroscopy under nearly identical experimental conditions. Our data reveal that the main structural rearrangement associated with the R–T transition takes place 2 μs after the photolysis of hemoglobin at room temperature and neutral pH. This finding suggests that the 20 μs step observed with time-resolved optical spectroscopy corresponds to a small and localized structural change
Miniature Wulff-type generator for improving feed to fuel cells /|nT.-S. Tan. -- 260 St. Catharines, Ont. : [s. n.],
No full textThe original objective of this work was to provide a simple generator
w.hich would produce hydrogen torLfuel-cell feed and which could be operated
under remote or northern conditions. A secondary objective was to maximize
the yield of hydrogen and carbon monoxide from available feed-stocks.
A search of the patent literature has indicated that the concept of
a small Wulff-type generator is essentially sound and that hydrogen may
be recovered from a wide variety of hydrocarbon feed-stocks.
A simple experimental set-up has been devised, patterned after ~~t
originally used by R. G. Wulff for producing acetylene. This provides
a supply of feed-stock, with or Without a carrier gas, which may be
passed directly through a heated tube, which may contain a catalyst.
A suitable procedure has been devised for analysi~ effluent gases
for hydrogen, oxygen, nitrogen, methane and carbon monoxide by gas
chromatography with the column packed with .Molecular .:>ieve .5 4.
Athanol with air a.s carrier gas and at the same time as oxidant
o was thermolyzed at temperatures in the ra~e 700-1100 C, with or Wi~lout
catalyst.
Methanol with or without nitrogen as a carrier gas was also cracked with
•
the same type of reactor refractory tube, but the temperature range
was lower t down to ,300 " C when a catalyst was used.
The problems of converting methane to hydrogen and carbon monoxide
effiCiently, using air and/or water as oxidants were also studied
Wulff shapes and the critical nucleus for a triangular Ising lattice
No full textEquilibrium Wulff shapes and interfacial energies of two-dimensional crystals on a triangular lattice are considered. Asymptotic approximations are constructed for both the shapes and energies in the limit T→0 where crystals are close to perfect hexagons, and the limit T→Tc (critical temperature) where crystals have near-circular shapes. The intermediate temperature region is studied numerically, and accurate interpolating approximations are proposed. The relevance of the study to the nucleation problem is discussed
Handwritten biographical information on Paulina T. McClung Merritt
No full textA handwritten biography of Paulina T. McClung Merritt by an unknown author, 1892.
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