A clinical comparison of visual acuity between the Cardiff acuity test and the Teller acuity and Snellen acuity tests in an adult population

The newly introduced Cardiff Acuity Test developed at the University of Wales College, Cardiff UK was compared to the standard Snellen Acuity charts and the Teller Acuity cards. Acuity readings were obtained from 100 eyes (50 subjects) at distances of 1 meter and 3 meters. A significant difference was found between the 3 acuity tests with a greater deviation at distance (3 meters) than at near (1 meter). The Teller cards measured the highest (best) acuity level followed by the Cardiff and the Sneilen measuring the lowest (worst) acuity

Benthic Macroinvertebrates as Indexes of Water Quality in the Upper Cuyahoga River

Author Institution: Department of Biology and Center for Environmental Studies, The University of AkronThe upper Cuyahoga River in northeastern Ohio is the major source of domestic water for the City of Akron, an important recreational area, and a designated Ohio Scenic River. Indexes of water quality based on benthic invertebrate community composition indicate a wide range in water quality along the river, but overall water quality is relatively high compared to areas of the Cuyahoga River below Akron and to most nearby river systems. Highest quality areas are located in the most headwater region and in the lowermost region near Lake Rockwell. These areas are characterized by a large number of taxa (>50), moderate density of organisms (= 2,000/m2), high ratios of scraper-grazers to detritivores (>0.5), high ratios of amphipods to isopods, and less than 1% organic pollution-tolerant organisms. Moderate degradation of water quality due to organic sedimentation in these areas is indicated by large proportions of organic pollution-facultative organisms (27-66%), especially a great variety of chironomids. Lowest quality areas occur 1-2 km below waste water outfalls from small villages and below groups of rural streamside dwellings. These areas are characterized by up to 62% fewer species, very low ratios of amphipods to isopods (usually <2), and large proportions of organic pollution-facultative and tolerant organisms (43-95%), especially chironomids and oligochaetes

Dependence in Prestroke Mobility Predicts Adverse Outcomes Among Patients With Acute Ischemic Stroke

Background and Purpose - Stroke survivors are commonly dependent in activities of daily living; however, the relation between prestroke mobility impairment and poststroke outcomes is poorly understood. The primary objective of this study was to evaluate the association between prestroke mobility impairment and 4 poststroke outcomes. The secondary objective was to evaluate the association between prestroke mobility impairment and a plan for physical therapy. Methods - This was a secondary analysis of the National Stroke Project data, a retrospective cohort of Medicare beneficiaries who were hospitalized with an acute ischemic stroke (1998 to 2001). Logistic-regression modeling was used to examine the adjusted association between prestroke mobility impairment with patient outcomes and a plan for physical therapy. Results - Among the 67 445 patients hospitalized with an ischemic stroke, 6% were dependent in prestroke mobility. Prestroke mobility dependence was independently associated with an increased odds of poststroke mobility impairment (odds ratio [OR]=9.9; 95% CI, 9.0 to 10.8); in-hospital mortality (OR=2.4; 95% CI, 2.2 to 2.7); discharge to a skilled nursing facility (OR=3.5; 95% CI, 3.2 to 3.8); and the combination of in-hospital death or discharge to a skilled nursing facility (OR=3.5; 95% CI, 3.3 to 3.8). Prestroke mobility dependence was independently associated with a decreased odds of having a plan for physical therapy (OR=0.79; 95% CI, 0.73 to 0.85). Conclusions - These data, obtained from a large, geographically diverse cohort from the United States, demonstrate a strong association between dependence in prestroke mobility and adverse outcomes among elderly stroke patients. Clinicians should screen patients for prestroke mobility impairment to identify patients at greatest risk for adverse events

Localized magnetoplasmon modes arising from broken translational symmetry in semiconductor superlattices

The electromagnetic propagator associated with the localized collective magnetoplasmon excitations in a semiconductor superlattice with broken translational symmetry, is calculated analytically within linear response theory. We discuss the properties of these collective excitations in both radiative and non-radiative regimes of the electromagnetic spectra. We find that low frequency retarded modes arise when the surface density of carriers at the symmetry breaking layer is lower than the density at the remaining layers. Otherwise a doublet of localized, high-frequency magnetoplasmon-like modes occurs.Comment: Revtex file + separate pdf figure

Clinical applicability of current pharmacokinetic models: Splanchnic elimination of 5-fluorouracil in cancer patients

What can be inferred from limited clinical data by using current models of hepatic elimination? We examined this question by analyzing previously published data on the steady-state uptake of the anticancer agent 5-fluorouracil (5-FU) in seven cancer patients in terms of the venous equilibration model, the undistributed and distributed forms of the sinusoidal perfusion model, and the convection-dispersion model. Because of appreciable extrasplanchnic removal of 5-FU, the value of the steady infusion rate was not used in our analysis. When the data from all patients were pooled by plotting the measured hepatic venous concentration against the measured hepatic arterial concentration, the high concentration data fell on a limiting straight line of slope 1, indicating that at high dose rates elimination of 5-FU in both the liver and gastrointestinal tract was close to saturation. The intercept of this line gave a model-independent estimate of V max /Q= 48.0± 11.6 (SD) μM for the pooled data set, where V max is the maximum splanchnic elimination rate of 5-FU, and Q is the hepatic blood flow. The low concentration data points fell on a limiting straight line through the origin, from which model-dependent values of the Michaelis constant were determined. The venous equilibration model gave K m =9.4 μM , while the undistributed sinusoidal perfusion model gave K m * =26,5 μM. With these values of K m , both models fit the pooled data equally well. These methods were applied to analyses of the five individual data sets which contained sufficiently high concentration data points. The resulting mean values were V max /Q=41.0±5.1 (sem) μM, K m =8.4±1.3μM and K m * =23.2±3.2 μM. However, the splanchnic region is a highly heterogeneous organ system, for which an undistributed analysis provides no more than an upper bound on the Michaelis constant K m + ( K m + ⩽ K m * ). A perfusion model distributed to represent total splanchnic elimination is developed in the Appendix. Using previous estimates of the degree of functional heterogeneity in the liver alone, this model yields K m + values for individual patients which have a mean of 20.3±2.8 μM .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45038/1/10928_2005_Article_BF01062135.pd

Optical characterization of porous alumina from vacuum ultraviolet to mid-infrared

Porous alumina was fabricated and optically characterized over a wide spectral range. Layers were formed electrochemically in oxalic acid solution from 10-μm-thick aluminum films evaporated onto silicon wafers. The layer formation was monitored with in situ spectroscopic ellipsometry in the visible and near-infrared wavelength range to accurately determine the thickness and dielectric functions. Anisotropy due to the columnar nature of the porous structure was determined using optical modeling. The porous alumina layer was found to have a small but significant absorption tail throughout the visible region. Atomic force microscopy and scanning electron microscopy were used throughout the process to assess the quality of pore formation. The mean pore center-to-center spacing was approximately 100 nm with thicknesses up to 5 μm. The infrared spectra revealed absorption peaks previously seen in ceramic alumina and peaks not associated with bulk alumina

Churn, Baby, Churn: Strategic Dynamics Among Dominant and Fringe Firms in a Segmented Industry

This paper integrates and extends the literatures on industry evolution and dominant firms to develop a dynamic theory of dominant and fringe competitive interaction in a segmented industry. It argues that a dominant firm, seeing contraction of growth in its current segment(s), enters new segments in which it can exploit its technological strengths, but that are sufficiently distant to avoid cannibalization. The dominant firm acts as a low-cost Stackelberg leader, driving down prices and triggering a sales takeoff in the new segment. We identify a “churn” effect associated with dominant firm entry: fringe firms that precede the dominant firm into the segment tend to exit the segment, while new fringe firms enter, causing a net increase in the number of firms in the segment. As the segment matures and sales decline in the segment, the process repeats itself. We examine the predictions of the theory with a study of price, quantity, entry, and exit across 24 product classes in the desktop laser printer industry from 1984 to 1996. Using descriptive statistics, hazard rate models, and panel data methods, we find empirical support for the theoretical predictions

Sources of variation in baseline gene expression levels from toxicogenomics study control animals across multiple laboratories

<p>Abstract</p> <p>Background</p> <p>The use of gene expression profiling in both clinical and laboratory settings would be enhanced by better characterization of variance due to individual, environmental, and technical factors. Meta-analysis of microarray data from untreated or vehicle-treated animals within the control arm of toxicogenomics studies could yield useful information on baseline fluctuations in gene expression, although control animal data has not been available on a scale and in a form best served for data-mining.</p> <p>Results</p> <p>A dataset of control animal microarray expression data was assembled by a working group of the Health and Environmental Sciences Institute's Technical Committee on the Application of Genomics in Mechanism Based Risk Assessment in order to provide a public resource for assessments of variability in baseline gene expression. Data from over 500 Affymetrix microarrays from control rat liver and kidney were collected from 16 different institutions. Thirty-five biological and technical factors were obtained for each animal, describing a wide range of study characteristics, and a subset were evaluated in detail for their contribution to total variability using multivariate statistical and graphical techniques.</p> <p>Conclusion</p> <p>The study factors that emerged as key sources of variability included gender, organ section, strain, and fasting state. These and other study factors were identified as key descriptors that should be included in the minimal information about a toxicogenomics study needed for interpretation of results by an independent source. Genes that are the most and least variable, gender-selective, or altered by fasting were also identified and functionally categorized. Better characterization of gene expression variability in control animals will aid in the design of toxicogenomics studies and in the interpretation of their results.</p

Amenability of groups and GG-sets

This text surveys classical and recent results in the field of amenability of groups, from a combinatorial standpoint. It has served as the support of courses at the University of G\"ottingen and the \'Ecole Normale Sup\'erieure. The goals of the text are (1) to be as self-contained as possible, so as to serve as a good introduction for newcomers to the field; (2) to stress the use of combinatorial tools, in collaboration with functional analysis, probability etc., with discrete groups in focus; (3) to consider from the beginning the more general notion of amenable actions; (4) to describe recent classes of examples, and in particular groups acting on Cantor sets and topological full groups

Noncomparabilities & Non Standard Logics

Many normative theories set forth in the welfare economics, distributive justice and cognate literatures posit noncomparabilities or incommensurabilities between magnitudes of various kinds. In some cases these gaps are predicated on metaphysical claims, in others upon epistemic claims, and in still others upon political-moral claims. I show that in all such cases they are best given formal expression in nonstandard logics that reject bivalence, excluded middle, or both. I do so by reference to an illustrative case study: a contradiction known to beset John Rawls\u27s selection and characterization of primary goods as the proper distribuendum in any distributively just society. The contradiction is avoided only by reformulating Rawls\u27s claims in a nonstandard form, which form happens also to cohere quite attractively with Rawls\u27s intuitive argumentation on behalf of his claims