11,271 research outputs found
On asymptotic dimension of groups
We prove a version of the countable union theorem for asymptotic dimension
and we apply it to groups acting on asymptotically finite dimensional metric
spaces. As a consequence we obtain the following finite dimensionality
theorems. A) An amalgamated product of asymptotically finite dimensional groups
has finite asymptotic dimension: asdim A *_C B < infinity. B) Suppose that G'
is an HNN extension of a group G with asdim G < infinity. Then asdim G'<
infinity. C) Suppose that \Gamma is Davis' group constructed from a group \pi
with asdim\pi < infinity. Then asdim\Gamma < infinity.Comment: Published by Algebraic and Geometric Topology at
http://www.maths.warwick.ac.uk/agt/AGTVol1/agt-1-4.abs.htm
Una relectura de la aclamación de João IV de Portugal en Cochin 1641 como espectáculo urbano y texto literario
The primary focus of this study is Agostinho de Almeida Gato’s extensive account of the celebrations held for the acclamation of John IV of Portugal in 1641 in Cochin. Drawing on studies of the Iberian monarchies as polycentric spaces, intellectual culture in the Estado da Índia and the historiography of early modern Iberian festival culture Gato’s text is analysed as both a testimony to the spectacle that was staged in Cochin and a text addressed to John IV in Portugal. Concerning the history of Cochin, and Portuguese India more broadly, it is argued that the spectacle of kingship staged by the festivities sought to underscore the significance of the oath of loyalty sworn by the population of Portuguese Cochin and address the interweaving of the concerns of the imperial, colonial and indigenous elites. Furthermore, consideration is given to how Gato’s account served as a form of a petition to the king.El objetivo principal de este estudio es llevar a cabo un análisis de la larga descripción, escrita por Agostinho de Almeida Gato, de las celebraciones que tuvieron lugar en Cochin en 1641 para festejar la aclamación del rey Juan IV de Portugal. A partir de los estudios sobre las monarquías ibéricas como espacios policéntricos, la cultura intelectual en el Estado da Índia y la historiografía acerca de la cultura festiva ibérica en la Edad Moderna temprana, se analiza el texto de Gato como testimonio del espectáculo celebrado en Cochin y como texto dirigido al rey Juan IV de Portugal. Respecto a la historia de Cochin y de la India portuguesa en general, se argumenta que el espectáculo de la realeza escenificado en las fiestas pretendía enfatizar el significado del juramento de lealtad prestado por la población de la Cochin portuguesa y abordar el entramado de las preocupaciones de las elites imperiales, coloniales e indígenas. Además, se examina cómo el relato de Gato sirvió como un tipo de petición al rey
Vortex information display system program description manual
A vortex information display system is described which provides flexible control through system-user interaction for collecting wing-tip-trailing vortex data, processing this data in real time, displaying the processed data, storing raw data on magnetic tape, and post processing raw data. The data is received from two asynchronous laser Doppler velocimeters (LDV's) and includes position, velocity, and intensity information. The raw data is written onto magnetic tape for permanent storage and is also processed in real time to locate vortices and plot their positions as a function of time. The interactive capability enables the user to make real time adjustments in processing data and provides a better definition of vortex behavior. Displaying the vortex information in real time produces a feedback capability to the LDV system operator allowing adjustments to be made in the collection of raw data. Both raw data and processing can be continually upgraded during flyby testing to improve vortex behavior studies. The post-analysis capability permits the analyst to perform in-depth studies of test data and to modify vortex behavior models to improve transport predictions
Adherence to Nutrition and Physical Activity Cancer Prevention Guidelines and Development of Colorectal Adenoma.
Adherence to the American Cancer Society's (ACS) Nutrition and Physical Activity Cancer Prevention Guidelines is associated with reductions in overall cancer incidence and mortality, including site-specific cancers such as colorectal cancer. We examined the relationship between baseline adherence to the ACS guidelines and (1) baseline adenoma characteristics and (2) odds of recurrent colorectal adenomas over 3 years of follow-up. Cross-sectional and prospective analyses with a pooled sample of participants from the Wheat Bran Fiber (n = 503) and Ursodeoxycholic Acid (n = 854) trials were performed. A cumulative adherence score was constructed using baseline self-reported data regarding body size, diet, physical activity and alcohol consumption. Multivariable logistic regression demonstrated significantly reduced odds of having three or more adenomas at baseline for moderately adherent (odds ratio [OR] = 0.67, 95% confidence intervals [CI]: 0.46⁻0.99) and highly adherent (OR = 0.50, 95% CI: 0.31⁻0.81) participants compared to low adherers (p-trend = 0.005). Conversely, guideline adherence was not associated with development of recurrent colorectal adenoma (moderate adherence OR = 1.16, 95% CI: 0.85⁻1.59, high adherence OR = 1.23, 95% CI: 0.85⁻1.79)
Brain amyloid in preclinical Alzheimer\u27s disease is associated with increased driving risk
INTRODUCTION: Postmortem studies suggest that fibrillar brain amyloid places people at higher risk for hazardous driving in the preclinical stage of Alzheimer's disease (AD). METHODS: We administered driving questionnaires to 104 older drivers (19 AD, 24 mild cognitive impairment, and 61 cognitive normal) who had a recent (18)F-florbetapir positron emission tomography scan. We examined associations of amyloid standardized uptake value ratios with driving behaviors: traffic violations or accidents in the past 3 years. RESULTS: The frequency of violations or accidents was curvilinear with respect to standardized uptake value ratios, peaking around a value of 1.1 (model r(2) = 0.10, P = .002); moreover, this relationship was evident for the cognitively normal participants. DISCUSSION: We found that driving risk is strongly related to accumulating amyloid on positron emission tomography, and that this trend is evident in the preclinical stage of AD. Brain amyloid burden may in part explain the increased crash risk reported in older adults
Step Position Distributions and the Pairwise Einstein Model for Steps on Crystal Surfaces
The Pairwise Einstein Model (PEM) of steps not only justifies the use of the
Generalized Wigner Distribution (GWD) for Terrace Width Distributions (TWDs),
it also predicts a specific form for the Step Position Distribution (SPD),
i.e., the probability density function for the fluctuations of a step about its
average position. The predicted form of the SPD is well approximated by a
Gaussian with a finite variance. However, the variance of the SPD measured from
either real surfaces or Monte Carlo simulations depends on , the
length of step over which it is calculated, with the measured variance
diverging in the limit . As a result, a length scale
can be defined as the value of at which the measured and
theoretical SPDs agree. Monte Carlo simulations of the terrace-step-kink model
indicate that , where is the correlation
length in the direction parallel to the steps, independent of the strength of
the step-step repulsion. can also be understood as the length over
which a {\em single} terrace must be sampled for the TWD to bear a "reasonable"
resemblence to the GWD.Comment: 4 pages, 3 figure
Effective piezoelectric activity of zinc oxide films grown by RF planar magnetron sputtering
We present a study of the effective piezoelectric activity of thin ZnO films produced by RF planar magnetron sputtering. The energetic plasma particles which bombard the substrate in the above deposition system increase the substrate temperature, thus causing a gradual variation in film structure during the beginning of the film growth. As a result, a precursor layer is formed which consists of small randomly oriented crystallites, and exhibits poor piezoelectric activity. Hence, the film thickness responsible for piezoelectric activity is generally less than the physical thickness of the film. This leads to an increase in the resonant frequency of the film. For example, a film designed to have a half-wave resonance at 288 MHz, was found to be resonant at 332 MHz. The poorly structured initial layer meant in this typical case that only 87 % of this film volume exhibited piezoelectric activity. Investigations based on the deposition conditions (substrate temperature, and deposition rate), the optical losses, SEM imaging and RF electrical behaviour are presented in this letter
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