Peripheral keratometry - accuracy and reliability in comparison to a corneal topography system, for application in rigid contact lens fitting

Peripheral keratometry was once a widely used practice in optometry. The technique fell out of vogue in the mid-1960s when questions arose concerning its accuracy. In this project, the accuracy of peripheral keratometry was reevaluated on 162 normal non-contact lens-wearing eyes. The results obtained by a Reichert keratometer and a fabricated plastic peripheral fixation device were statistically compared to data obtained by the Humphreys MasterVue corneal keratoscopic mapping system. Patients were asked to fixate on a point 13mm from the center of a plastic disc overlaid onto the keratometer mire plate. The curvature value achieved with this fixation was then compared to the curvature value taken 3.0mm from the center of the corneal topographic map. Results show a high correlation(\u3e 90%) between the mid-peripheral corneal curvature data obtained with the peripheral keratometry disc and data obtained by the corneal mapping system 3.0mm from center. Results from this study also indicate that the keratometer, when used with a peripheral fixation device, can yield data just as accurate as the corneal topography system (p-value \u3e 0.05). Clinical application of this procedure could prove beneficial to the general11 optometric practitioner who fits rigid contact lenses but may not be able to afford an expensive corneal mapping system

Evanescent Black Holes

A renormalizable theory of quantum gravity coupled to a dilaton and conformal matter in two space-time dimensions is analyzed. The theory is shown to be exactly solvable classically. Included among the exact classical solutions are configurations describing the formation of a black hole by collapsing matter. The problem of Hawking radiation and backreaction of the metric is analyzed to leading order in a $1/N$ expansion, where $N$ is the number of matter fields. The results suggest that the collapsing matter radiates away all of its energy before an event horizon has a chance to form, and black holes thereby disappear from the quantum mechanical spectrum. It is argued that the matter asymptotically approaches a zero-energy ``bound state'' which can carry global quantum numbers and that a unitary $S$-matrix including such states should exist.Comment: 14 page

Black Holes with a Massive Dilaton

The modifications of dilaton black holes which result when the dilaton acquires a mass are investigated. We derive some general constraints on the number of horizons of the black hole and argue that if the product of the black hole charge $Q$ and the dilaton mass $m$ satisfies $Q m < O(1)$ then the black hole has only one horizon. We also argue that for $Q m > O(1)$ there may exist solutions with three horizons and we discuss the causal structure of such solutions. We also investigate the possible structures of extremal solutions and the related problem of two-dimensional dilaton gravity with a massive dilaton.Comment: 36 pages with 5 figures (as uuencoded compressed tar file) (revised version has one major change in bound on mass for extremal solution and minor typos fixed), harvma

Reconstructing the global topology of the universe from the cosmic microwave background

If the universe is multiply-connected and sufficiently small, then the last scattering surface wraps around the universe and intersects itself. Each circle of intersection appears as two distinct circles on the microwave sky. The present article shows how to use the matched circles to explicitly reconstruct the global topology of space.Comment: 6 pages, 2 figures, IOP format. To be published in the proceedings of the Cleveland Cosmology and Topology Workshop 17-19 Oct 1997. Submitted to Class. Quant. Gra

Hairy Black Holes in String Theory

Solutions of bosonic string theory are constructed which correspond to four-dimensional black holes with axionic quantum hair. The basic building blocks are the renormalization group flows of the CP1 model with a theta term and the SU(1,1)/U(1) WZW coset conformal field theory. However the solutions are also found to have negative energy excitations, and are accordingly expected to decay to the vacuum.Comment: 14 pages (References added

High Rate of Microbleed Formation Following Primary Intracerebral Hemorrhage

Background We sought to investigate the frequency of microbleed development following intracerebral hemorrhage in a predominantly African-American population and to identify predictors of new microbleed formation. Aims and/or hypothesis To investigate the frequency and predictors of new microbleeds following intracerebral hemorrhage. Methods The DECIPHER study was a prospective, longitudinal, magnetic resonance-based cohort study designed to evaluate racial/ethnic differences in risk factors for microbleeds and to evaluate the prognostic impact of microbleeds in this intracerebral hemorrhage population. We evaluated new microbleed formation in two time periods: from baseline to 30 days and from 30 days to year 1. Results Of 200 subjects enrolled in DECIPHER, 84 had magnetic resonance imaging at all required time points to meet criteria for this analysis. In the baseline to day 30 analysis, 11 (13·1%) had new microbleeds, compared with 25 (29·8%) in the day 30 to year 1 analysis. Logistic regression analysis demonstrated that baseline number of microbleeds [odds ratio 1·05 (95% confidence interval 1·01, 1·08), P = 0·01] was associated with new microbleed formation at 30 days. A logistic regression model predicting new microbleed at one-year included baseline number of microbleeds [odds ratio 1·05 (1·00, 1·11), P = 0·046], baseline age [odds ratio 1·05 (1·00, 1·10), P = 0·04], and white matter disease score [odds ratio 1·18 (0·96, 1·45). P = 0·115]. Overall, 28 of 84 (33·3%) intracerebral hemorrhage subjects formed new microbleeds at some point in the first year post-intracerebral hemorrhage. Conclusions We found that one-third of intracerebral hemorrhage subjects in this cohort surviving one-year developed new microbleeds, which suggests a dynamic and rapidly progressive vasculopathy. Future studies are needed to examine the impact of new microbleed formation on patient outcomes

Novel algorithmic approach predicts tumor mutation load and correlates with immunotherapy clinical outcomes using a defined gene mutation set

BACKGROUND: While clinical outcomes following immunotherapy have shown an association with tumor mutation load using whole exome sequencing (WES), its clinical applicability is currently limited by cost and bioinformatics requirements. METHODS: We developed a method to accurately derive the predicted total mutation load (PTML) within individual tumors from a small set of genes that can be used in clinical next generation sequencing (NGS) panels. PTML was derived from the actual total mutation load (ATML) of 575 distinct melanoma and lung cancer samples and validated using independent melanoma (n = 312) and lung cancer (n = 217) cohorts. The correlation of PTML status with clinical outcome, following distinct immunotherapies, was assessed using the Kaplan–Meier method. RESULTS: PTML (derived from 170 genes) was highly correlated with ATML in cutaneous melanoma and lung adenocarcinoma validation cohorts (R(2) = 0.73 and R(2) = 0.82, respectively). PTML was strongly associated with clinical outcome to ipilimumab (anti-CTLA-4, three cohorts) and adoptive T-cell therapy (1 cohort) clinical outcome in melanoma. Clinical benefit from pembrolizumab (anti-PD-1) in lung cancer was also shown to significantly correlate with PTML status (log rank P value < 0.05 in all cohorts). CONCLUSIONS: The approach of using small NGS gene panels, already applied to guide employment of targeted therapies, may have utility in the personalized use of immunotherapy in cancer. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12916-016-0705-4) contains supplementary material, which is available to authorized users

Quantum Topologically Massive Gravity in de Sitter Space

We consider three dimensional gravity with a positive cosmological constant and non- zero gravitational Chern-Simons term. This theory has inflating de Sitter solutions and local metric degrees of freedom. The Euclidean signature partition function of the theory is evaluated including both perturbative and non-perturbative corrections. The perturbative one-loop correction is computed using heat kernel techniques. The non- perturbative corrections come from gravitational instantons with non-trivial topology which can be enumerated explicitly. We compute the sum over an infinite class of ge- ometries and show that, unlike the case of pure Einstein gravity, the partition function is finite. This demonstrates that the inclusion of non-trivial local degrees of freedom can render the sum over geometries convergent.Comment: 25 pages, 1 figure; v2: minor correction

Genomic Signatures of Strain Selection and Enhancement in Bacillus atrophaeus var. globigii, a Historical Biowarfare Simulant

(BG) as a simulant for biological warfare (BW) agents, knowledge of its genome composition is limited. Furthermore, the ability to differentiate signatures of deliberate adaptation and selection from natural variation is lacking for most bacterial agents. We characterized a lineage of BGwith a long history of use as a simulant for BW operations, focusing on classical bacteriological markers, metabolic profiling and whole-genome shotgun sequencing (WGS). on the nucleotide level. WGS of variants revealed that several strains were mixed but highly related populations and uncovered a progressive accumulation of mutations among the “military” isolates. Metabolic profiling and microscopic examination of bacterial cultures revealed enhanced growth of “military” isolates on lactate-containing media, and showed that the “military” strains exhibited a hypersporulating phenotype.Our analysis revealed the genomic and phenotypic signatures of strain adaptation and deliberate selection for traits that were desirable in a simulant organism. Together, these results demonstrate the power of whole-genome and modern systems-level approaches to characterize microbial lineages to develop and validate forensic markers for strain discrimination and reveal signatures of deliberate adaptation