3,781 research outputs found
The great maze, and The heart of youth; a poem and a play,
No full textMode of access: Internet.Presentation copy to Ridgely and Olivia Torrence with inscription by the author
Chip-Firing Revisited: A Peek into the Third Dimension
No full textChip-firing was first introduced as a probabilistic game. Subsequently, it was generalized to arbitrary graph configurations and investigated mostly with regard to two-dimensional quad-grid layouts. In this paper, we lift chip-firing to the third dimension. Aside from the arising three-dimensional shapes, we are interested in the internal, two-dimensional structures. Furthermore, we explore the different shapes obtained by chip firing processes on various neighborhoods, such as the face-centered and the cube-centered grid as well as on a neighborhood inspired by knight moves.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Computer Graphics and Visualisatio
Methods and processes of developing the Strengthening the Reporting of Observational studies in Epidemiology - Veterinary (STROBE-Vet) Statement
No full textAbstractBackgroundThe reporting of observational studies in veterinary research presents many challenges that often are not adequately addressed in published reporting guidelines.ObjectiveTo develop an extension of the STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) statement that addresses unique reporting requirements for observational studies in veterinary medicine related to health, production, welfare, and food safety.DesignA consensus meeting of experts was organized to develop an extension of the STROBE statement to address observational studies in veterinary medicine with respect to animal health, animal production, animal welfare, and food safety outcomes.SettingConsensus meeting May 11–13, 2014 in Mississauga, Ontario, Canada.ParticipantsSeventeen experts from North America, Europe, and Australia attended the meeting. The experts were epidemiologists and biostatisticians, many of whom hold or have held editorial positions with relevant journals.MethodsPrior to the meeting, 19 experts completed a survey about whether they felt any of the 22 items of the STROBE statement should be modified and if items should be added to address unique issues related to observational studies in animal species with health, production, welfare, or food safety outcomes. At the meeting, the participants were provided with the survey responses and relevant literature concerning the reporting of veterinary observational studies. During the meeting, each STROBE item was discussed to determine whether or not re-wording was recommended, and whether additions were warranted. Anonymous voting was used to determine whether there was consensus for each item change or addition.ResultsThe consensus was that six items needed no modifications or additions. Modifications or additions were made to the STROBE items numbered: 1 (title and abstract), 3 (objectives), 5 (setting), 6 (participants), 7 (variables), 8 (data sources/measurement), 9 (bias), 10 (study size), 12 (statistical methods), 13 (participants), 14 (descriptive data), 15 (outcome data), 16 (main results), 17 (other analyses), 19 (limitations), and 22 (funding).LimitationPublished literature was not always available to support modification to, or inclusion of, an item.ConclusionThe methods and processes used in the development of this statement were similar to those used for other extensions of the STROBE statement. The use of this extension to the STROBE statement should improve the reporting of observational studies in veterinary research related to animal health, production, welfare, or food safety outcomes by recognizing the unique features of observational studies involving food-producing and companion animals, products of animal origin, aquaculture, and wildlife
Exploring Mathematics with Curvagon Tiles
No full textBuilding blocks and tiles are an excellent way of learning about geometry and mathematics in general. There are several versions of tiles that are either snapped together or connected with magnets that can be used to introduce topics like volume, tessellations, and Platonic solids. However, since these tiles are made of hard plastic, they are not very suitable for creating hyperbolic surfaces or shapes where the tiles need to bend. Curvagons are flexible regular polygon building blocks that allow you to quickly build anything from hyperbolic surfaces and tori to dinosaurs and shoes. They can be used to introduce mathematical concepts from Archimedean solids to Gauss-Bonnet theorem. You can also let your imagination run free and build whatever comes to mind.Statistic
From natural hazard to environmental catastrophe: Past and present
No full textThe number of environmental catastrophes is rising, mostly owing to an increase in hydrometeorological hazards. The number of disasters is escalating as the world population grows and people settle in marginal areas. In order to improve preparedness, the geological and archaeological records must be investigated as they hold a wider range of possible events than the much shorter instrumental record. Catastrophes will gain amplitude with rapid onset, long duration, larger affected area, inflexible society and, of cause, convergence of threats. Too often, it seems that today’s societies resist learning from the past and therefore tend to repeat errors. A new field of science is emerging: the science of environmental catastrophes, which requires not only robust chronologies to firmly link cause and effect, but also bridges the crossing between the geosciences and social sciences
Fission track dating of obsidian source samples from the Willaumez Peninsula, Papua New Guinea and eastern Australia
No full textFigure 1. Plateau age for Australian obsidian AU602 obtained by using isothermal treatment (upper represented by squares). Induced (pyramids) and spontaneous (circles) fission-track diameters at each step of thermal treatment (lower).Published as part of Bonetti, R., Di Cesare, P., Guglielmetti, A., Malerba, F., Migliorini, E., Oddone, M., Bird, J. R., Torrence, Robin & Bultitude, R. J., 1998, Fission track dating of obsidian source samples from the Willaumez Peninsula, Papua New Guinea and eastern Australia, pp. 277-284 in Records of the Australian Museum 50 (3) on page 279, DOI: 10.3853/j.0067-1975.50.1998.1286, http://zenodo.org/record/465313
Measurement of Collins asymmetries in inclusive production of charged pion pairs in e+e− annihilation at BABAR
No full textWe present measurements of Collins asymmetries in the inclusive process e+e−→ππX, where π stands for charged pions, at a center-of-mass energy of 10.6 GeV. We use a data sample of 468 fb−1 collected by the BABAR experiment at the PEP-II B factory at SLAC, and consider pairs of charged pions produced in opposite hemispheres of hadronic events. We observe clear asymmetries in the distributions of the azimuthal angles in two distinct reference frames. We study the dependence of the asymmetry on several kinematic variables, finding that it increases with increasing pion momentum and momentum transverse to the analysis axis, and with increasing angle between the thrust and beam axis
FIGURES 17–23 in New Linyphiidae spiders associated with playas in the Southern High Plains (Llano Estacado) of Texas (Arachnida: Araneae)
No full textFIGURES 17–23. Male and female Erigone denticulata Chamberlin & Ivie 1939 from playas in Briscoe County, Texas. 17, carapace of male; 18, pedipalpus of male, ventral view; 19, enlarged view of pedipalpal tibia of male, ventral view; 20, pedipalpal tibia of male, dorsal view; 21, epigynum, ventral view; 22, spermathecae, posterior view; 23, spermathecae, dorsal view. Abbreviations used: CD copulatory ducts, D patellar denticle, E embolus, FD fertilization ducts, PA patellar apophysis, PC paracymbium, SA suprategular apophysis, S spermatheca, TA tegular apophysis, TE tegulum, Terminology follows Hormiga (2000). Scale bars for figures 17, 18 = 0.25 mm, all other figures = 0.05 mm.Published as part of Cokendolpher, James C., Torrence, Shannon M., Smith, Loren M. & Dupérré, Nadine, 2007, New Linyphiidae spiders associated with playas in the Southern High Plains (Llano Estacado) of Texas (Arachnida: Araneae), pp. 49-60 in Zootaxa 1529 on page 58, DOI: 10.5281/zenodo.17765
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Determination of electroweak parameters at the SLC
No full textWe present an improved measurement of the left-right cross section asymmetry (A{sub LR}) for Z{sup 0} boson production by e{sup +}e{sup -} collisions. The measurement was performed at a center-of-mass energy of 91.28 GeV with the SLD detector at the SLAC Linear Collider (SLC) during the 1994-95 running period. The luminosity-weighted average polarization of the SLC electron beam during this run was measured to be (77.23 {+-} 0.52)%. Using a sample of 93,644 hadronic Z{sup 0} decays, we measure the pole asymmetry A{sub LR}{sup 0} to be 0.1512 {+-} 0.0042(stat.) {+-} 0.0011(syst.) which is equivalent to an effective weak mixing angle of sin{sup 2} {theta}{sub W}{sup eff} = 0.23100 {+-} 0.00054(stat.) {+-} 0.00014(syst.). We also present a preliminary direct measurement of the Z{sup 0}-lepton coupling asymmetries A{sub e}, A{sub {mu}}, and A{sub {tau}} extracted from the differential cross section observed in leptonic Z{sup 0} decays. We combine these results with our previous A{sub LR} measurement to obtain a combined determination of the weak mixing angle sin{sup 2} {theta}{sub W}{sup eff} = 0.23061 {+-} 0.00047
Three mathematical sculptures for the mathematikon
No full textThree stainless steel sculptures, designed by Dutch mathematical artist Koos Verhoeff, were installed at the new Mathematikon building of Heidelberg University. Lobke consists of six conical segments connected into a single convoluted strip. One side is polished, the other side is matte (blasted), to emphasize the two-sided nature of the strip. The shape derives from an Euler cycle on the octahedron. Balancing Act is a figure-eight knot, made from 16 polished triangular beam segments, 4 longer and 12 shorter segments. As a freestanding object it balances on a single short segment. Each beam runs parallel to one of the four main diagonals of a cube. Hamilton Cycle on Football is a Hamilton cycle on the traditional football (soccer ball), constructed from 60 matte square beams. Mathematicians know the traditional football as a truncated icosahedron, consisting of 12 pentagons and 20 hexagons, giving rise to 60 vertices
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