Discontinuous shear modulus determines the glass transition temperature

A solid - amorphous or crystalline - is defined by a finite shear modulus while a fluid lacks such. We thus experimentally investigate the elastic properties of a colloidal glass former near the glass transition: spectroscopy of vibrational excitations yields the dispersion relations of longitudinal and transverse phonons in the glassy state. From the long wavelength limit of the dispersion relation we extract the bulk and the shear modulus. As expected, the latter disappear in a fluid and we measure a clearly resolved discontinuous behaviour of the elastic moduli at the glass transition. This not only determines the transition temperature T_G of the system but also directly addresses recent discussions about elasticity during vitrification. We show that low frequency excitations in our system are plane waves such that continuum elasticity theory can be used to describe the macroscopic behaviour.Comment: 8 pages, 6 figure

Adsorption of atomic oxygen (N2O) on a clean Si(100) surface and its influence on the surface state density; A comparison with O2

This paper describes a study concerning the interaction of molecular oxygen (O2) and nitrous oxide (N2O) with the clean Si(100) 2 × 1 surface in ultrahigh vacuum at 300 K. Differential reflectometry (DR) in the photon energy range of 1.5¿4.5 eV, Auger electron spectroscopy (AES) and low energy electron diffraction (LEED) have been used to monitor these solid-gas reactions. With this combination of techniques it is possible to make an analysis of the (geometric and electronic) structure and chemical composition of the surface layer. The aim of the present study was to give a description of the geometric nature of the oxygen covered Si(100) surface. For that purpose we have used both molecular (O2) and atomic oxygen (as released by decomposition of N2O) to oxidize the clean Si(100)2 × 1 surface

Robot-Assisted Radical Cystectomy in the Management of Bladder Cancer

The application of robotic technology to laparoscopic surgery has the potential to revolutionize the entire field of urology. The use of robotic-assisted radical cystectomy has been demonstrated in the literature only within the past 3 years, as much of the reconstruction and urinary diversion techniques associated with radical cystectomy are considered more technically challenging than other procedures. Here we review the available literature pertaining to this procedure, which consists of a limited number of case reports, case series, and pilot or feasibility studies. While theses results seem to point towards less blood loss, lower transfusion rates, and shorter hospital stays compared to open radical cystectomy, definitive conclusions and recommendations cannot yet be made because of a lack of larger and/or prospective studies or randomized trials

Effects of Mowing Frequency on the Yield and Protein Content of Several Grasses Grown in Pure Stands

This paper presents results of a five-year experiment conducted at the Agricultural Experiment Station, Lincoln, Nebraska, on the adaptation, yield, and quality of several grasses subjected to different frequencies of harvest as a means of determining their forage value

Introduced Forage Grasses for Nebraska

This circular presents illustrations, descriptions and recommended usage of fourteen introduced cultivated grasses that are worthy of practical consideration in Nebraska. Most of them can easily be identified by comparing plant specimens with the illustrations and descriptions. This circular has been prepared for use by farmers, county agricultural agents, teachers and others who are interested in our most important grasses. Station Circular 59 contains information and illustrations of the more common native perennial grasses of Nebraska

Earthquake-Induced Parameter Automation

An operating automated system has been developed for Wappapello Dam. The system allows periodic reading of foundation pore pressure sensors. Upon sensing strong ground shaking the system reads rock and foundation triaxial acceleration. The acceleration readings cause the system to collect pore pressure rise in a loose, saturated sand. The data is available over telephone lines in real time. In addition to reducing maintenance piezometer reading labor, the automation performs earthquake triggering notification and remote data evaluation. The engineering use for dam safety review is considered invaluable

Elastic Behavior of a Two-dimensional Crystal near Melting

Using positional data from video-microscopy we determine the elastic moduli of two-dimensional colloidal crystals as a function of temperature. The moduli are extracted from the wave-vector-dependent normal mode spring constants in the limit $q\to 0$ and are compared to the renormalized Young's modulus of the KTHNY theory. An essential element of this theory is the universal prediction that Young's modulus must approach $16 \pi$ at the melting temperature. This is indeed observed in our experiment.Comment: 4 pages, 3 figure

Visual Data Mining

Occlusion is one of the major problems for interactive visual knowledge discovery and data mining in the process of finding patterns in multidimensional data.This project proposes a hybrid method that combines visual and analytical means to deal with occlusion in visual knowledge discovery called as GLC-S which uses visualization of n-D data in 2D in a set of Shifted Paired Coordinates (SPC). A set of Shifted Paired Coordinates for n-D data consists of n/2 pairs of common Cartesian coordinates that are shifted relative to each other to avoid their overlap. Each n-D point A is represented as a directed graph A* in SPC, where each node is the 2D projection of A in a respective pair of the Cartesian coordinates. The proposed GLC-S method significantly decrease cognitive load for analysis of n-D data and simplify pattern discovery in n-D data. The GLC-S method iteratively splits n-D data into non-overlapping clusters (hyper-rectangles) around local centers and visualizes only data within these clusters at each iteration. The requirements for these clusters are to contain cases of only one class and be the largest cluster with this property in SPC visualization. Such sequential splitting allows: (1) avoiding occlusion, (2) finding visually local classification patterns, rules, and (3) combine local sub-rules to a global rule that classifies all given data of two or more classes. The computational experiment with Wisconsin Breast Cancer data(9-D), User Knowledge Modeling data(6-D), and Letter Recognition data(17-D) from UCI Machine Learning Repository confirm this capability. At each iteration, these data have been split into training (70%) and validation (30%) data. It required 3 iterations in Wisconsin Breast Cancer data, 4 iterations in User Knowledge Modeling and 5 iterations in Letter Recognition data and respectively 3, 4, 5 local sub-rules that covered over 95% of all n-D data points with 100% accuracy at both training and validation experiments. After each iteration, the data that were used in this iteration are removed and remaining data are used in the next iteration. This removal process helps to decrease occlusion too. The GLC-S algorithm refuses to classify remaining cases that are not covered by these rules, i.e.,., do not belong to found hyper-rectangles. The interactive visualization process in SPC allows adjusting the sides of the hyper-rectangles to maximize the size of the hyper-rectangle without its overlap with the hyper-rectangles of the opposing classes. The GLC-S method splits data using the fixed split of n coordinates to pairs. This hybrid visual and analytical approach avoids throwing all data of several classes into a visualization plot that typically ends up in a messy highly occluded picture that hides useful patterns. This approach allows revealing these hidden patterns. The visualization process in SPC is reversible (lossless). i.e.,., all n-D information is visualized in 2D and can be restored from 2D visualization for each n-D case. This hybrid visual analytics method allowed classifying n-D data in a way that can be communicated to the user’s in the understandable and visual form

Exploratory topic modeling with distributional semantics

As we continue to collect and store textual data in a multitude of domains, we are regularly confronted with material whose largely unknown thematic structure we want to uncover. With unsupervised, exploratory analysis, no prior knowledge about the content is required and highly open-ended tasks can be supported. In the past few years, probabilistic topic modeling has emerged as a popular approach to this problem. Nevertheless, the representation of the latent topics as aggregations of semi-coherent terms limits their interpretability and level of detail. This paper presents an alternative approach to topic modeling that maps topics as a network for exploration, based on distributional semantics using learned word vectors. From the granular level of terms and their semantic similarity relations global topic structures emerge as clustered regions and gradients of concepts. Moreover, the paper discusses the visual interactive representation of the topic map, which plays an important role in supporting its exploration.Comment: Conference: The Fourteenth International Symposium on Intelligent Data Analysis (IDA 2015

Assessing Face Validity of a Physical Activity Questionnaire for Spanish-Speaking Women in California

To create a culturally appropriate assessment, the study reported here developed and evaluated the face validity of a visually enhanced Spanish-language physical activity questionnaire. A professional translated the English version of the International Physical Activity Questionnaire (IPAQ), and an expert panel subsequently reviewed it. Photos of individuals engaged in physical activity behaviors were added. Cognitive interviews were completed with low-income Spanish-speaking women in California (n=20). Questionnaire text was modified and then reviewed by translation experts (n=7). With a high readability score of 98, the questionnaire demonstrates adequate face validity and is ready for further validation