[Clinical practice variation in cataract surgery]. / Variabilidad clínica en la cirugía de la catarata.

PURPOSE: Cataract surgery rates have dramatically increased in the last two decades. However, clinical practice variation in cataract surgery has not been thoroughly studied. The aim of this review is to analyze clinical practice variation, including the causes and consequences of this phenomenon. Then, its role in health care planning and health care quality is focused, emphasizing the importance of reducing it and providing several practical strategies to accomplish it. RECENT FINDINGS: The latest researches are presented in this article. They identify the development and implementation of clinical practice guidelines as the best tool to standardize care processes. CONCLUSION: Managing unwarranted or unwanted variation would improve quality of care and may lead to a significant saving in health care spending.

Pattern recognition procedures for differentiation of Green, Black and Oolong teas according to their metal content from inductively coupled plasma atomic emission spectrometry.

Eight metals Zn, Mn, Mg, Cu, Al, Ca, Ba and K selected as chemical descriptors were analysed by inductively coupled plasma atomic emission spectrometry. The metal profile was studied in 48 samples of commercial tea - 26 black, 18 green, and four Oolong teas. Pattern recognition procedures such as display methods (Principal Component analysis and Cluster analysis) and supervised techniques (Linear Discriminant analysis and Artificial Neural Networks trained by back propagation) were applied to attain the differentiation of the three tea classes.

Intra-laboratory testing of method accuracy from recovery assays.

A revision on intra-laboratory testing of accuracy of analytical methods from recovery assays is given. Procedures based on spiked matrices and spiked samples are presented and discussed.

Inorganic indicators of the origin of edible salts marketed in Spain from a chemometric approach.

Twenty edible salts marketed in Spain were studied for content of inorganic constituents in order to identify one or more indicators of the origins of salts. In Spain the principal source of salt is seawater, either from the Mediterranean coast or from the Atlantic coast. In addition, some manufactured salts in the dietary category were also considered. Five "Atlantic," 12 "Mediterranean," and 3 dietary salts were analyzed for potassium, magnesium, calcium, strontium, manganese, zinc, and sulfate contents and for alkalinity. Salt samples were first dried for moisture determination. Metals were determined by inductively coupled plasma atomic emission spectrometry, sulfate was determined by turbidimetry, and alkalinity was determined by titration with hydrochloric acid. All the results were expressed as the means for triplicate experiments, as mg of analyte per kg of salt on a dry basis. From these results and by application of chemometric strategies (principal component analysis, variable-variable plots, and cluster analysis) it was found that the potassium content distinguishes sea salts from dietary salts very well, and the contents of strontium and manganese discriminate salts of Atlantic origin versus salts of Mediterranean origin. Dietary salts showed levels of potassium higher than the sea salts, and salts of Atlantic origin had greater strontium and manganese content values than salts of Mediterranean origin.

Estimation of pH and autoprotolysis constants in mixtures of aliphatic amides with water: Medium effect on the 4-aminoazobenzene system.

Correction factors to the glass electrode and autoprotolysis constants of mixtures of aliphatic amides with water: N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), N-methylformamide (NMF), N-methylacetamide (NMA), formamide (F) and acetamide (A), have been determined. The acidity constants of 4-aminoazobenzene referred to the standard state of the mixtures of these aliphatic amides with water as well as the medium effect on the 4-aminoazobenzene system have been evaluated from spectrophotometric measurements.

Spectrophotometric determination of copper in foods, feedingstuffs and plants: a comparison between the glyoxal bis(4-phenyl-3-thiosemicarbazone) and bathocuproine disulphonate methods.

In this paper, both glyoxal bis(4-phenyl-3-thiosemicarbazone) (GBPT) and bathocuproine disulphonate (BCDS) methods for copper have been applied to the spectrophotometric determination of copper in foods, feedingstuffs and plants. Results obtained in both cases are typical of those expected for good spectrophotometric procedures. However, the GBPT method affords the distinct advantage of direct use in acidic solution without the necessity of neutralization and pH adjustment, being thus more satisfactory for unskilled usage.