RESUMEN
A new class of 'soft' particles, micelles, is detected electrochemically via 'nano-impacts' for the first time. Short, sharp bursts of current are used to indicate the electrical contact of a single CTAB (cetyltrimethylammonium bromide) micelle with an electrode via the oxidation of the bromide content. The variation in CTAB concentration for such 'nano-impact' experiments shows that a significant number of 'spikes' are observed above the CMC (critical micelle concentration) and this is attributed to the formation of micelles. A comparison with dynamic light scattering is also reported.
Asunto(s)
Lesión Renal Aguda/diagnóstico por imagen , Septicemia Hemorrágica/complicaciones , Necrosis de la Corteza Renal/diagnóstico por imagen , Infecciones Meningocócicas/complicaciones , Neisseria meningitidis/aislamiento & purificación , Púrpura/complicaciones , Lesión Renal Aguda/etiología , Adulto , Femenino , Humanos , Necrosis de la Corteza Renal/etiología , Tomografía Computarizada por Rayos XRESUMEN
Interventional cardiology procedures can involve high doses to patients and, in particular, to patients' skin, the tissue at greatest risk of deterministic injuries. The evaluation of skin dose from interventional procedures is recommended, but difficult because of the amount of different X-ray fields and projections used in a procedure. For this reason, a retrospective follow-up study has been developed to identify skin injuries in patients submitted to one or more cardiac interventions in the Udine hospital between 1998 and 2002. Seventy-eight patients with a cumulative dose-area product >300 Gy cm2 were selected from 3332 patients, who underwent 5039 procedures. In this group the maximum skin dose was 6.7 Gy. The clinical follow-up, performed using the LENT-SOMA methodology, has not detected skin injuries and this result allows a frequency to be estimated for skin injuries in patients undergoing repeated cardiac procedures of <3 x 10(-4) in our centre.
Asunto(s)
Cardiología/métodos , Traumatismos por Radiación/diagnóstico , Radiodermatitis/diagnóstico , Radiología Intervencionista/métodos , Piel/lesiones , Piel/efectos de la radiación , Anciano , Algoritmos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Dosis de Radiación , Protección Radiológica , Estudios Retrospectivos , Factores de Tiempo , Rayos XRESUMEN
A method based on image quality criteria (QC) for cine-angiography was developed to measure the quality of cine-angiograms (CA). A series of 30 CA for left ventriculography (LV) and left and right coronary angiography (LCA, RCA) have been scored and 172 readings were obtained. Standard deviation of quality scores indicated the reproducibility of the method. Each part of CA was examined separately, giving scores for LV, LCA and RCA and a total score (TS), with clinical (C) and technical (T) criteria defined and examined separately. In 83% of the studies TS was >0.8 and with standard deviation from 0.02 to 0.21. In general, LV had a lower score and greater disagreement compared with RCA and LCA. Disagreement was greater in T, compared with C. In conclusion, these results indicate that QC, translated into a scoring system, yields reproducible data on the quality of cardiac images.
Asunto(s)
Cineangiografía/métodos , Angiografía Coronaria/métodos , Intensificación de Imagen Radiográfica/métodos , Ventrículos Cardíacos/patología , Humanos , Variaciones Dependientes del Observador , Control de Calidad , Reproducibilidad de los Resultados , Rayos XRESUMEN
We strive to predict the function mapping and rules performed by a trained perceptron from studying the weights. We derive a few properties of the trained weights and show how the perceptron's representation of knowledge, rules and functions depend on these properties. Two types of perceptrons are studied--one case with continuous inputs and one hidden layer, the other a simple binary classifier with boolean inputs and no hidden units.
