Cutaneous findings in a case of psittacosis

Semel, J. D.

doi:10.1001/archderm.120.9.1227

Cited by 7 publications

(4 citation statements)

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“…HIV 84 Psittacosis 85 Chikungunya infection 86 Mononucleosis 87 Hepatitis C 88 'Puffy hand syndrome' 89,90 cryoglobulins, and may be the presenting symptom. 32,153 Multiple reports describe an association between acrocyano sis and cold agglutinins, cryoglubulins, or cryofibrino gen. 28,33,[154][155][156] Almost a third of all patients with positive antiphospholipid antibodies have acrocyanosis.…”

Section: Secondary Acrocyanosismentioning

confidence: 99%

“…In infections, acrocyanosis may be associated with hypoxemia, the presence of cryoglobulins, or DIC, 85 although the exact mechanisms may be complex. In some infections and in sarcoidosis, acrocyanosis is asso ciated with reactive angioendotheliomatosis character ized by proliferation of cells in the reticular and papillary dermal capillaries and venules.…”

Section: Secondary Acrocyanosismentioning

confidence: 99%

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Acrocyanosis: The Flying Dutchman

2011

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Acrocyanosis is symmetric, painless, discoloration of different shades of blue in the distal parts of the body that is marked by symmetry, relative persistence of the skin color changes with aggravation by cold exposure, and frequent association with local hyperhidrosis of hands and feet. Described over a century ago and despite seeming familiarity, it remains a poorly understood condition that shares much in clinical presentation with other conditions characterized by skin color changes in the distal parts of the body. The diagnosis remains mostly clinical, and pathological mechanisms vary suggesting that acrocyanosis may not be a single entity. We performed an extensive literature review to summarize existing knowledge about the demographics, pathology, diagnosis, and treatment of this condition.

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Section: Secondary Acrocyanosismentioning

confidence: 99%

Section: Secondary Acrocyanosismentioning

confidence: 99%

Acrocyanosis: The Flying Dutchman

2011

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“…Despite the strong nonlinearity and nonlocality inherent to the radiative transfer, it has been possible to develop some simple diagnostics during the past years: the line ratio technique (Stenflo 1973(Stenflo , 2010(Stenflo , 2011, the center-of-gravity method (Semel 1970;Rees & Semel 1979), and calibration curves between spectral line summaries and certain magnetic field properties (e.g., Lites et al 2008;Martínez Pillet et al 2011, for recent applications).…”

Section: Introductionmentioning

confidence: 99%

Sparse inversion of Stokes profiles

Ramos

Rodríguez

2015

A&A

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Context. Inversion codes are numerical tools used to infer physical properties from observations. Despite their success, the quality of current spectropolarimetric observations and those expected in the near future presents a challenge to current inversion codes. Aims. The pixel-by-pixel strategy of inverting spectropolarimetric data that we currently use needs to be surpassed and improved. The inverted physical parameters have to take into account the spatial correlation that is present in the data and that contains valuable physical information. Methods. We used the concept of sparsity or compressibility to develop a new generation of inversion codes for the Stokes parameters. The inversion code uses numerical optimization techniques based on the idea of proximal algorithms to impose sparsity. In so doing, we allow for the first time exploiting the spatial correlation on the maps of physical parameters. Sparsity also regularizes the solution by reducing the number of unknowns. Results. We compare the results of the new inversion code with pixel-by-pixel inversions to demonstrate the increased robustness of the solution. We also show how the method can easily compensate for the effect of the telescope point spread function, producing solutions with an enhanced contrast.

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“…Among them, the line ratio technique (Stenflo 1973(Stenflo , 2010(Stenflo , 2011, the center-of-gravity method (Semel 1970;Rees & Semel 1979), and the application of calibration curves between spectral line and magnetic field properties (e.g., Lites et al 2008;Martínez Pillet et al 2011, for recent applications) have had special relevance.…”

Section: Introductionmentioning

confidence: 99%

Model Selection for Spectropolarimetric Inversions

Ramos

Sainz

González

et al. 2012

ApJ

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Inferring magnetic and thermodynamic information from spectropolarimetric observations relies on the assumption of a parameterized model atmosphere whose parameters are tuned by comparison with observations. Often, the choice of the underlying atmospheric model is based on subjective reasons. In other cases, complex models are chosen based on objective reasons (for instance, the necessity to explain asymmetries in the Stokes profiles) but it is not clear what degree of complexity is needed. The lack of an objective way of comparing models has, sometimes, led to opposing views of the solar magnetism because the inferred physical scenarios are essentially different. We present the first quantitative model comparison based on the computation of the Bayesian evidence ratios for spectropolarimetric observations. Our results show that there is not a single model appropriate for all profiles simultaneously. Data with moderate signal-to-noise ratios (S/Ns) favor models without gradients along the line of sight. If the observations show clear circular and linear polarization signals above the noise level, models with gradients along the line are preferred. As a general rule, observations with large S/Ns favor more complex models. We demonstrate that the evidence ratios correlate well with simple proxies. Therefore, we propose to calculate these proxies when carrying out standard least-squares inversions to allow for model comparison in the future.

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Cutaneous findings in a case of psittacosis

Cited by 7 publications

References 0 publications

Acrocyanosis: The Flying Dutchman

Acrocyanosis: The Flying Dutchman

Sparse inversion of Stokes profiles

Model Selection for Spectropolarimetric Inversions

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