Holder exponent spectra for human gait

The stride interval time series in normal human gait is not strictly constant, but fluctuates from step to step in a complex manner. More precisely, it has been shown that the control process for human gait is a fractal random phenomenon, that is, one with a long-term memory. Herein we study the Holder exponent spectra for the slow, normal and fast gaits of 10 young healthy men in both free and metronomically triggered conditions and establish that the stride interval time series is more complex than a monofractal phenomenon. A slightly multifractal and non-stationary time series under the three different gait conditions emerges.Comment: 23 pages, 12 figures, 9 Table

Direct Observation of the Fourth Star in the Zeta Cancri System

Direct imaging of the zeta Cnc system has resolved the fourth star in the system, which is in orbit around zeta Cnc C. The presence of the fourth star has been inferred for many years from irregularities in the motion of star C, and recently from C's spectroscopic orbit. However, its mass is close to that of C, making its non-detection puzzling. Observing at wavelengths of 1.2, 1.7, and 2.2 microns with the adaptive-optics system of the CFHT, we have obtained images which very clearly reveal star D and show it to have the color of an M2 star. Its brightness is consonant with its being two M stars, which are not resolved in our observations but are likely to be in a short-period orbit, thereby accounting for the large mass and the difficulty of detection at optical wavelengths, where the magnitude difference is much larger. The positions and colors of all four stars in the system are reported and are consistent with the most recent astrometric observations.Comment: 7 pages including 3 tables, 1 figure; To appear in PAS

Distribution, Habitat Partitioning, and Abundance of Atlantic Spotted Dolphins, Bottlenose Dolphins, and Loggerhead Sea Turtles on the Eastern Gulf of Mexico Continental Shelf

We surveyed cetaceans and marine turtles from Nov. 1998 to Nov. 2000 along a series of prescribed transects between Tampa Bay and Charlotte Harbor, Florida, and between the coast and the 180-m isobath. Vertical profiles of temperature, salinity, and chlorophyll concentration were collected at 65 stations, and continuous surface data on these variables and transmittance were collected while underway. Habitat partitioning among Atlantic spotted dolphins (Stenella frontalis), bottlenose dolphins (Tursiops truncatus), and loggerhead sea turtles (Caretta caretta) was examined by canonical correspondence analyses of environmental characteristics at sighting locations. Environmental characteristics and primary productivity of S. frontalis and T. truncatus habitat on the eastern Gulf of Mexico continental shelf significantly differed. In shelf waters shallower than 20 m, T. truncatus were the dominant cetacean species, whereas S. frontalis were the most common shelf species at depths of 20-180 m. Environmental preferences of C. caretta were intermediate between the two dolphin species and showed no apparent relationship with depth. The continental shelf in the eastern Gulf of Mexico is broad, with distances from coast to slope as great as 200 km. Although S. frontalis habitat has elsewhere been described as ubiquitous over the shelf, our data suggest that S. frontalis in the eastern Gulf of Mexico prefer midshelf habitat

Structure determination from powder data : Mogul and CASTEP

When solving the crystal structure of complex molecules from powder data, accurately locating the global minimum can be challenging, particularly where the number of internal degrees of freedom is large. The program Mogul provides a convenient means to access typical torsion angle ranges for fragments related to the molecule of interest. The impact that the application of modal torsion angle constraints has on the structure determination process of two structure solution attempts using DASH is presented. Once solved, accurate refinement of a molecular structure against powder data can also present challenges. Geometry optimisation using density functional theory in CASTEP is shown to be an effective means to locate hydrogen atom positions reliably and return a more accurate description of molecular conformation and intermolecular interactions than global optimisation and Rietveld refinement alone

Information activity in serious leisure

Background. In the past decade, scholars of information science have started to conduct research on information behaviour in serious leisure. Presently, these studies lack common concepts and terms and empirical discoveries are not easy to assemble into theory. Aim. This conceptual and methodological paper surveys the aforementioned research area and introduces Anders Hektor’s model of information behaviour in conjunction with the serious leisure perspective as a means to systematically study information behaviour in serious leisure. Method. Three methods are employed. The first is a selective literature review and intellectual history of research into information behaviour in serious leisure. The second is a conceptual analysis of Hektor’s model that relates its key features to the serious leisure perspective. The third consists of a deductive audit of three forms of serious leisure (the liberal arts hobby, amateur musicianship, and the hobby of running), utilizing the frameworks, concepts, and terms outlined in the paper. Results. Studies of information behaviour in serious leisure have increased and deepened in the past decade, largely through ideographic case studies. Hektor’s model of information behaviour, with its locus in everyday life and precise delineation of eight information activities, can complement such research designs. A deductive audit guided by Hektor’s model illuminated information activities within the three forms of serious leisure and enabled comparative observations. Conclusions. When combined with the serious leisure perspective, Hektor’s model enables research that is comparative and more precise. However, the extent to which this model captures physical or embodied information should be further examined

Pullet Rearing Programs.

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Microscopic calculation of the phonon-roton branch in superfluid 4^4He

Diffusion Monte Carlo results for the phonon-roton excitation branch in bulk liquid $^4$He at zero temperature are presented. The sign problem associated to the excited wave function has been dealt both with the fixed-node approximation and the released-node technique. The upper bounds provided by the fixed-node approximation are shown to become exact when using the released-node method. An excellent agreement with experimental data is achieved both at the equilibrium and near the freezing densities.Comment: 12 pages, RevTex, 3 ps figures include