26,921 research outputs found
The Correlation of Dental Arch Width and Ethnicity
This study sought to demonstrate a correlation between arch width, ethnic background, individual height, weight, and whether orthodontic treatment had been rendered. Conclusions revealed that arch widths were significantly larger (p= 0.002 for the mandible and p= 0.008 for the maxilla) in non-Whites than in Whites. In addition, arch widths of the mandible were significantly larger in individuals who had had orthodontic treatment compared to those who had not (p=0.005). This did not carry through to those arch widths in the maxilla of orthodontic versus nonorthodontic care (p=0.258)
The Quantification of Tooth Displacement
By using reference points from a single pixel marker placed at the center point of the cuspid teeth and the center point on each of the incisor teeth, a polynomial curve was generated as a native curve for each dental arch studied. The polynomial curve generated from actual tooth position in each arch provides the forensic odontologist with another reference point that is quantifiable. The study represents that individual characteristics, such as tooth displacement, can be quantified in a simple, reliable, and repeatable format
Producing power-law distributions and damping word frequencies with two-stage language models
Standard statistical models of language fail to capture one of the most striking properties of natural languages: the power-law distribution in the frequencies of word tokens. We present a framework for developing statisticalmodels that can generically produce power laws, breaking generativemodels into two stages. The first stage, the generator, can be any standard probabilistic model, while the second stage, the adaptor, transforms the word frequencies of this model to provide a closer match to natural language. We show that two commonly used Bayesian models, the Dirichlet-multinomial model and the Dirichlet process, can be viewed as special cases of our framework. We discuss two stochastic processes-the Chinese restaurant process and its two-parameter generalization based on the Pitman-Yor process-that can be used as adaptors in our framework to produce power-law distributions over word frequencies. We show that these adaptors justify common estimation procedures based on logarithmic or inverse-power transformations of empirical frequencies. In addition, taking the Pitman-Yor Chinese restaurant process as an adaptor justifies the appearance of type frequencies in formal analyses of natural language and improves the performance of a model for unsupervised learning of morphology.48 page(s
Towards the First Galaxies
The formation of the first galaxies at redshifts z~10-15 signaled the
transition from the simple initial state of the universe to one of ever
increasing complexity. We here review recent progress in understanding their
assembly process with numerical simulations, starting with cosmological initial
conditions and modelling the detailed physics of star formation. In particular,
we study the role of HD cooling in ionized primordial gas, the impact of UV
radiation produced by the first stars, and the propagation of the supernova
blast waves triggered at the end of their brief lives. We conclude by
discussing promising observational diagnostics that will allow us to probe the
properties of the first galaxies, such as their contribution to reionization
and the chemical abundance pattern observed in extremely low-metallicity stars.Comment: 12 pages, 14 figures, appeared in "First Stars III", eds. B. O'Shea,
A. Heger and T. Abel, a high resolution version (highly recommended) can be
found at http://www.ita.uni-heidelberg.de/~tgreif/files/gjb07.pd
An experimental 100 kilowatt wind turbine generator
Experimental generator consists of two blades mounted on 100 foot tower, driving transmission train and electric generator mounted on top of tower. Machine generates 100 kW of electricity at wind speeds from 18 to 60 miles per hour. Yaw control mechanism automatically orients machine into wind
Quantification of the Individual Characterstics of the Human Dentition: Methodology
This study provides a method for comparing six individual human dentition characteristics using the standard measuring tool in Adobe Photoshop CS2 as compared to measuring individual characteristics with an automated software program under development at Marquette University, which has been adapted for bitemark analysis. The algorithm identifies color-specific pixels and automatically calculates the measurements
The Commercialization of Space Transportation: Exploring the Impact of the National Space Transportation Policy
The 1994 National Space Transportation Policy designates the roles of the DoD, NASA and the Departments of Transportation and Commerce to identify and promote innovative types of arrangements between the U.S. government and the private sector in order to reduce the cost to access space. DoD, civil and commercial industry leaders agree that the price to access space is currently exorbitantly expensive. The solution to this expense, which the United States Government is relying upon, is the commercialization of space transportation technology. This research focuses on investigating the industry and policy commercialization trends which led to the 1994 NSTP, and reports on compliance with the policy. Through policy literature review, case study analysis and interviews, the impact of the National Space Transportation Policy on commercializing space transportation is determined. Research focuses on space transportation participants who have done the most to shape the commercialization policy over the past decade. Results indicate that the 1988-1994 period, leading to the 1994 NSTP, was shaped by the NASA and DoD stakeholders\u27 assertions for expanded bureaucratic control of the nation\u27s space transportation resources. After the 1994 NSTP, in the period of 1995-1998, the commercialization of space technology has been increasing slowly, with innovative arrangements evolving each year
A Methodology for Three-Dimensional Quantification of Anterior Tooth Width
The use of cone-beam computed tomography (CBCT) technology has been shown to be more accurate in measuring individual incisor tooth widths than the use of wax exemplars. There were fewer differences by investigators using CBCT than others using an F-test in a mixed model of the measurement differences of investigators, wax type, and which tooth was measured. In addition, the frequency of outliers was less in the CBCT method (a total of 5) as compared to the two-dimensional measurements in ether Aluwax (a total of 8) or Coprwax (a total of 12). Both results indicate that CBCT measurements accounted more precisely for tooth width and level of eruption
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