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Background: Dementia of the Alzheimer's type (DAT) impacts Hispanics disproportionately, with almost a twofold elevated risk of developing DAT, as well as earlier onset of the disease, than in non-Hispanic Whites. However, the role of main risk factors for DAT, such as APOE-ϵ4 and blood pressure (BP) levels, remains uncertain among Hispanics. Objective: To investigate the association of APOE-ϵ4 and BP levels, measures with 24-h ambulatory BP monitoring, with incidence of DAT in an elderly cohort of Hispanics. Methods: 1,320 participants from the Maracaibo Aging Study, free of dementia at the baseline, and with ambulatory BP measurements and APOE genotype available were included. Adjusted Cox proportional models were performed to examine 1) the incidence of DAT and 2) the relationship between BP levels and DAT according to APOE genotypes. Models were adjusted by competing risk of death before the onset of DAT. Model performance was assessed by likelihood test. Results: The average follow-up time was 5.3 years. DAT incidence was 5.8 per 1000 person-year. APOE-ϵ4 carriers had a higher risk of DAT. In unadjusted analyses, conventional, 24-h, and nighttime systolic BP levels were significantly higher in participants who developed DAT and of APOE-ϵ4 carriers (p < 0.05). After adjustment for competing risks, only higher nighttime systolic BP was associated with DAT incidence, but only among subjects carrying APOE-ϵ4. Conclusion: In this Hispanic population, both APOE-ϵ4 genotype and assessment of nocturnal systolic BP (rather than diurnal or office BP) were necessary to estimate DAT risk. © 2020 - IOS Press and the authors. All rights reserved. more...

Many hot corrosion problems in industrial and utility boilers are caused by molten salts. The corrosion processes which occur in salts are of an electrochemical nature, and so they can be studied using electrochemical test methods. In this research, electrochemical techniques in molten salt systems have been used for the measurements of molten corrosion processes. Electrochemical test methods are described here for a salt mixture of 80%V2O5-20%Na2SO4 at 540-680°C. To establish better the electrochemical corrosion rate mearurements for molten salt systems, information from electrochemical potentiodynamic polarization curves, such as polarization resistance and Tafel slopes were used in this study to generate corrosion rate data. The salt was contained in a quartz crucible inside a stainless steel retort. The atmosphere used was air. A thermocouple sheathed with quartz glass was introduced into the molten salt for temperature monitoring and control. Two materials were tested in the molten mixture: SA213-T22 and SA213-TP347H steels. The corrosion rates values obtained using electrochemical methods were around 0.58-7.14 mm/yr (22.9-281 mpy). The corrosion rate increase with time.Muchos problemas de corrosión por depósitos salinos en la industria eléctrica, especialmente en los generadores de vapor, se deben al ataque por sales fundidas. El proceso de corrosión en sales fundidas es de naturaleza electroquímica; así, puede estudiarse empleando técnicas electroquímicas. Este proceso de corrosión en un sistema de sales fundidas, mezcla de 80%V2O5 y 20%Na2SO4 a temperaturas comprendidas entre 540 y 680°C, se evaluó en esta investigación por medio de técnicas electroquímicas. Para medir la velocidad de corrosión por depósitos salinos se parte de curvas de polarización potenciodinámicas determinando la resistencia de polarización por extrapolación de las pendientes de Tafel. Las sales se fundieron en un crisol de cuarzo dentro de un soporte de acero inoxidable. La atmósfera empleada fue aire; un termopar tipo K cubierto con tubo de cuarzo se introdujo en la sal fundida para controlar la temperatura del medio. En la mezcla fundida se evaluaron dos materiales: SA213-T22 y SA213-TP347H. Los valores de la velocidad de corrosión obtenidos empleando técnicas electroquímicas están entre de 0,58-7,14 mm/año (22,9-281 mpy). La velocidad de corrosión se incrementa con el tiempo. more...

If you can not measure it you can not manage it (Cox, 2002).If you can not measure it with known precision and exactness you can not make unbiased conclusions. A diversified quatifying Fractal Geometry´s toolbox (Mandelbrot, 2002) enables the Earth Science with precise measures of scale invariance, universality, non linearity, complexity, criticality etc. However, the absence of the reference techniques for measurement of complex system basic attributes, as well as the lack of standards and quality assurance for analysis of sometimes extensive data surveys, makes difficult (why not impossible!) any comparison between conclusions derived, either from empirical observations or theoretical analyses.We use the basic principles of Metrology concerned with measurement, uncertainty and bias analysis (International Vocabularity of Basic and general terms in Metrology, 2004) in order to design the basic concepts of Fractal Metrology, devoted to the standard measurement of basic attributes of rough nonlinear sets and processes. more...

En base a estudios con elemento finito, en el presente trabajo se obtiene un modelo capaz de predecir la cantidad de acero corroído (rcrit) en la armadura necesaria para que aparezca la primera grieta visible en la superficie del recubrimiento del hormigón. Para el análisis con elemento finito se utiliza el software ANSYS, el cual dispone del elemento SOLID65, con el que es posible modelar el hormigón simple, ya que tiene la capacidad de sufrir aplastamiento en compresión y agrietarse a tracción. El caso de la capa de óxido es modelado mediante elementos de contacto CONTA174, y la armadura con SOLID65, pero sin las opciones de aplastamiento y agrietamiento. El modelo obtenido está en función del recubrimiento libre, diámetro del refuerzo, tipo de hormigón y la longitud corroída, denominada ésta longitud anódica. Los resultados muestran la gran influencia que tiene la corrosión localizada (longitud anódica pequeña-longitud catódica grande) sobre el cálculo de rcrit, y que dicho efecto sólo es posible analizarlo de manera tridimensional. Así mismo, se muestra la eficiencia de utilizar los elementos de contacto CONTA174 para representar el crecimiento de óxidos. El modelo obtenido explica en un 92% el fenómeno y se compara con resultados experimentales encontrados en la literatura more...

Many hot corrosion problems in industrial and utility boilers are caused by molten salts. The corrosion processes which occur in salts are of an electrochemical nature, and so they can be studied using electrochemical test methods. In this research, electrochemical techniques in molten salt systems have been used for the measurements of molten corrosion processes. Electrochemical test methods are described here for a salt mixture of 80%V2O5-20%Na2SO4 at 540-680°C. To establish better the electrochemical corrosion rate mearurements for molten salt systems, information from electrochemical potentiodynamic polarization curves, such as polarization resistance and Tafel slopes were used in this study to generate corrosion rate data. The salt was contained in a quartz crucible inside a stainless steel retort. The atmosphere used was air. A thermocouple sheathed with quartz glass was introduced into the molten salt for temperature monitoring and control. Two materials were tested in the molten mixture: SA213-T22 and SA213-TP347H steels. The corrosion rates values obtained using electrochemical methods were around 0.58-7.14 mm/yr (22.9-281 mpy). The corrosion rate increase with time. Muchos problemas de corrosión por depósitos salinos en la industria eléctrica, especialmente en los generadores de vapor, se deben al ataque por sales fundidas. El proceso de corrosión en sales fundidas es de naturaleza electroquímica; así, puede estudiarse empleando técnicas electroquímicas. Este proceso de corrosión en un sistema de sales fundidas, mezcla de 80%V2O5 y 20%Na2SO4 a temperaturas comprendidas entre 540 y 680°C, se evaluó en esta investigación por medio de técnicas electroquímicas. Para medir la velocidad de corrosión por depósitos salinos se parte de curvas de polarización potenciodinámicas determinando la resistencia de polarización por extrapolación de las pendientes de Tafel. Las sales se fundieron en un crisol de cuarzo dentro de un soporte de acero inoxidable. La atmósfera empleada fue aire; un termopar tipo K cubierto con tubo de cuarzo se introdujo en la sal fundida para controlar la temperatura del medio. En la mezcla fundida se evaluaron dos materiales: SA213-T22 y SA213-TP347H. Los valores de la velocidad de corrosión obtenidos empleando técnicas electroquímicas están entre de 0,58-7,14 mm/año (22,9-281 mpy). La velocidad de corrosión se incrementa con el tiempo. more...

We studied 26 patients (p) with end stage renal failure (RF) and 26 healthy volunteers (HV) to investigate the prevalence of Helicobacter pylori (Hp) and its relation with chronic gastritis (CG) and chronic duodenitis (CD). We analyzed 312 gastric and duodenal mucosal biopsies stained with HE and Giemsa. Categorical data were assessed by the X2 and Fisher's exact test. Probability values of p0.05 were considered significant. Endoscopic lesions correlated with histological gastritis and duodenitis and Hp was positive in antrum of 6/8p (75%) (p0.05). The prevalence of Hp was 54.5% (15/26p) in RF and 47.2% (12/26s) in HV. Hp was found more frequently in pathological mucosa (p005.). CG of the antrum and CD were more commonly in RF (88.5% vs 69.5% and 42.3% vs 23.1% respectively). HP was more frequently located in the antrum than in body and duodenum in both groups (p0.05). Chronic gastritis of the body was more frequently in HV (p0.05). Active chronic antral gastritis and superficial gastritis were more frequently associated to Hp. Hp was associated to chronic inflammatory gastroduodenal diseases in both groups and may be a cofactor in its pathogenesis. We recommended Hp treatment before renal transplantation. more...

Non-ulcer dyspepsia is a frequent clinical entity characterized by chronic upper gastrointestinal symptoms without organic lesions by radiology, sonography or endoscopy. We studied simultaneously the rate of gastric emptying and gallbladder contraction in 10 patients with non-ulcer dyspepsia and in 10 healthy controls after ingestion of 500 cc of isotonic saline, and 500 cc of a liquid mixed meal, hypercaloric and hyperosmotic. The measurements were done by direct real-time ultrasonic imaging in fasting and were repeated at regular intervals (15-30 minutes) after the liquid meal, until complete gastric emptying was established. We found with the liquid mixed meal, the patients with non-ulcer dyspepsia had a significant delay in gastric emptying and gallbladder hypokinesis with faulty contraction and slow refilling. Dynamic ultrasonographic studies are useful in patients with non-ulcer dyspepsia. more...

The rate of gastric emptying of different liquid solutions was measured in 80 voluntary normal young male subjects (mean age 19.9 +/- 1.6 years) by direct real-time ultrasonic imaging. Multiple US scans were repeated at regular intervals (15-30 minutes) until complete gastric emptying was established, after ingestion of 500 cc of 8 different liquid test meals: isotonic saline, 50% glucose, 5% glucose, 40 g of proteins, 20 g of protein, 40 g of fat, 20 g of fat and mixed (carbohydrates, proteins and fat). Eight groups of ten subjects were studied, each one with a different test meal. Three types of gastric emptying were identified: slow (177 +/- 12 minutes) in subjects receiving 50% glucose, 40 and 20 grs of proteins and mixed test meals; intermediate (83 +/- 9 minutes) with 5% glucose, 40 and 20 g of fat; rapid (40 +/- 6 minutes) with isotonic saline. The mixed diet had the slowest emptying time (210 +/- 6 min). Our results are in accordance with published data regarding gastric motor physiology and demonstrates the usefulness of ultrasound in the study of gastric emptying of fluids. more...

This paper reports a case of an histological non aggressive thymoma with myasthenic symptoms as the first clinical manifestation. Three years after its complete surgical resection liver metastases appeared without evidence of intrathoracic neoplastic disease. The extrathoracic metastases are uncommon and the thymomatous myasthenia gravis is present in 25 to 50% of cases. We reviewed the literature and analyzed its clinical pathological characteristics and therapeutics approach. more...

There are many discrepancies between reports about gallbladder motility in gallstones disease. We studied gallbladder volume and contraction in 65 patients with asymptomatic gallstones and compared with 65 healthy controls by ultrasonography. The mass of the stones was less of the 25% of the gallbladder volume. We related stone size and number with its motor function. The results of the gallbladder contraction (GC) in the control group was 79.5% (DS = 9.5) and in the cholelithiasis group was 59.9% (DS = 19) with (p0.01). We found that the cholelithiasis group was heterogeneous and on closer inspection the patients fell into two subgroups separated by the inferior limit of normal GC (60%). The subgroup I (41 patients) had a fasting volume (FV) of 26.6 ml (DS = 14.1), a postprandial volume (PV) of 6.5 ml (DS = 3.8) and a GC of 75.3% (DS = 8.5). The subgroup II (24 patients) had a FV of 27.3 ml (DS = 20.3), a PV of 16.9 ml (DS = 15) and a GC of 40.5% (DS = 11.8). There was significant differences in PV and GC (p0.01). We concluded that defective gallbladder emptying is evident in a subgroup of patients but gallbladder contraction may be normal in patients with cholelithiasis and there are, not correlation between GC and the number and size of the stones. more...