Oregon Physics (United States)

ABSTRACT The anomalous linear birefringence of mixed crystals, inconsistencies between optical and morphological symmetries, have been studied more extensively for mixed crystals of isomorphic cubic nitrates of strontium, barium and lead than for any other family of laboratory‐grown crystals. Anomalous circular birefringence, an unanticipated dissymmetry leading to different refractivities for circularly polarized rays, on the other hand, is harder to detect and has not been described in two centuries during which the etiologies of optical anomalies were debated. We quantify anomalous circular birefringence in Ba x Pb 1‐ x (NO 3 ) 2 and Sr x Pb 1‐ x (NO 3 ) 2 mixed crystals using polarimetric imaging. This circular birefringence is not natural optical activity but arises from the non‐commutativity of successive linearly anisotropic sub‐volumes that intersect the incident wave vector. The signal is best described as an emergent optical activity generated by orientation gradients across linearly birefringent domains. The effect was simulated by treating each growth sector as a uniaxial crystal misaligned with respect to the adjacent sector oriented along an adjacent cube body diagonal. The magnitude and spatial distribution of the experimentally observed linear and circular retardance are reproduced with fidelity.

In this study, we identify the minimal important difference for two patient-reported quality of life instruments and provide evidence for their validity in pyoderma gangrenosum (PG). Such patient-reported outcome measures are being considered as co-primary endpoints in PG clinical trials by the US Food and Drug Administration.

The in vitro permeation test (IVPT) using ex vivo human skin is a sensitive and robust model system that has been vital in elucidating the fundamental parameters surrounding the absorption of both therapeutic agents and industrial chemicals through skin. FDA and OECD IVPT Guidances recommend that each skin section selected for study should be screened prior to use to ensure that the stratum corneum integrity is retained. Three methods are currently considered acceptable: 1) transepidermal water loss (TEWL), 2) electrical resistance, and 3) tritiated water (3H2O) absorption. A retrospective analysis of data from the authors' laboratory has been performed with the objective of addressing a number of questions regarding the 3H2O and TEWL integrity tests, and the population attributes of a large database consisting of 17,330 individual skin sections obtained from 459 skin donors. The applicability and usefulness of these tests, when compared to companion permeation data obtained from 25 topical drug products, has also been examined. Both integrity tests found water permeability to be equal in White and Hispanic races but higher than in Blacks, 3H2O being more discriminating than TEWL. Male skin is more permeable than female and there is a slight decrease in permeability with advancing age in both groups. Correlation between 3H2O absorption and drug absorption revealed a minimal relationship between the two in most cases, the Pearson correlation coefficient ranging from -0.417 to 0.953. Additionally, drug outliers were not always identified with a failing integrity test. The results call for a critical reexamination of the value of the 3H2O integrity test, and by extension, TEWL, for use in IVPT studies.

To report a case of pigmented paravenous retinochoroidal atrophy in a patient that was found to have an autosomal dominant pathogenic variant of the hexokinase 1 ( HK1 ) gene. A case report. A 41-year-old White woman with a distant family history of retinitis pigmentosa presented with a 5-year history of bilateral blurry and decreased vision that led to eventual loss of ability to drive. Color funduscopic photographs revealed retinochoroidal atrophy, hyper-reflective spots within the retina, and a paravenous distribution of pigment bilaterally. Given the patient's familial ocular history and workup, she was diagnosed with inherited retinal degeneration with phenotype suggestive of pigmented paravenous retinochoroidal atrophy. Genetic testing revealed a single rare variant, c.2551 G>A in the HK1 gene. This case describes a pathogenic variant in HK1 , a gene that has been associated with RP, but has not been previously reported in association with the pigmented paravenous retinochoroidal atrophy phenotype. This expands the phenotypes associated with HK1 pathogenic variant, p.Glu851Lys, and the genetic association of pigmented paravenous retinochoroidal atrophy to include HK1 . Although pigmented paravenous retinochoroidal atrophy has been previously reported to be associated with CRB1 gene, no previous relationship to the HK1 gene has been described.

In earlier chapters, we discussed aspects of computer architecture and how to efficiently program and deploy software. Thus far, we’ve been successful getting computers to carry out what they have been programmed to accomplish. Beyond traditional programming, questions arise about whether or not computers can mimic humans in terms of intelligence and learning. In science fiction literature, there are many stories of machines taking over the world. Is this possible? Until relatively recently, these fictions have been given little credence because there are fundamental differences between how human intelligence and computing machines work. Machines act as obedient servants – working as they are explicitly programmed to accomplish a well-defined task. They did not learn and improve or develop intelligence. And that’s where machine learning comes to play. Some of the most succinct descriptions of machine learning are from Stanford and McKinsey & Co. As per Stanford, “Machine learning is the science of getting computers to act without being explicitly programmed.” And, as per McKinsey & Co, “Machine learning is based on algorithms that can learn from data without relying on rules-based programming.”

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Letters4 June 2019Stroke Rate Variation and Anticoagulation Benefit in Atrial FibrillationDavid A. Nardone, MDDavid A. Nardone, MDHillsboro, Oregon (D.A.N.)Search for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/L19-0127 SectionsAboutFull TextPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail TO THE EDITOR:I read Shah and colleagues' article (1) with great interest. Does the old adage still ring true: Is the risk for stroke the same whether one has paroxysmal, persistent, or permanent AF? I would like to see data on strokes and bleeding among patients who received anticoagulation; were documented over time to have paroxysmal, persistent, or permanent AF; and have CHA2DS2-VASc scores greater than 1.Reference1. Shah SJ, Eckman MH, Aspberg S, Go AS, Singer DE. Effect of variation in published stroke rates on the net clinical benefit of anticoagulation for atrial fibrillation. Ann Intern Med. 2018;169:517-27. [PMID: 30264130]. doi:10.7326/M17-2762 LinkGoogle Scholar Author, Article, and Disclosure InformationAffiliations: Hillsboro, Oregon (D.A.N.)Disclosures: The author has disclosed no conflicts of interest. The form can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=L19-0127. PreviousarticleNextarticle Advertisement FiguresReferencesRelatedDetailsSee AlsoEffect of Variation in Published Stroke Rates on the Net Clinical Benefit of Anticoagulation for Atrial Fibrillation Sachin J. Shah , Mark H. Eckman , Sara Aspberg , Alan S. Go , and Daniel E. Singer Stroke Rate Variation and Anticoagulation Benefit in Atrial Fibrillation Linda P.T. Joosten , Sander van Doorn , Frans H. Rutten , and Geert-Jan Geersing Stroke Rate Variation and Anticoagulation Benefit in Atrial Fibrillation Sachin J. Shah and Daniel E. Singer Stroke Rate Variation and Anticoagulation Benefit in Atrial Fibrillation Martin Mayer , Brian S. Alper , and Louis Leff Stroke Rate Variation and Anticoagulation Benefit in Atrial Fibrillation James A. Reiffel Metrics 4 June 2019Volume 170, Issue 11Page: 818KeywordsAtrial fibrillationConflicts of interestDisclosureHemorrhageStroke ePublished: 4 June 2019 Issue Published: 4 June 2019 Copyright & PermissionsCopyright © 2019 by American College of Physicians. All Rights Reserved.PDF downloadLoading ...