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M Aldana

Publications and source records attributed to M Aldana.

7 recordsLinked to original sources

Statistical characterization of random electrostatic potentials

In this work we study statistical properties of random electrostatic potentials generated by one dimensional lattices with random charges. We show that the resulting random potentials are correlated Gaussian processes, satisfying the Lindeberg version of the central limit theorem, if certain restrictions are imposed on the individual potentials generated by the particles on the lattice. Since most of the point-particle electrostatic potentials occurring in nature satisfy the Lindeberg condition, the correlation properties of the random potentials are not arbitrary and must comply with the central limit theorem. Based on this theorem we can obtain explicit expressions for these correlations. We thus are able to give a characterization of a broad class of potentials yielding feasible physical scenarios. We illustrate some consequences of our findings by considering dynamical properties of a test particle interacting with the lattice. We show how the long range correlations generate statistical features in these properties, which are best exhibited when considering different length scales.

Journal Article↗

Primitive molecular machine scenario for the origin of the three base codon composition.

We set up a scenario for the operation of primordial synthesis machines operating in outer space quasi one dimensional channels, where polymers interact with fixed particles. The scheme allows for polymerization, translocation and translation. We will show that under very general conditions the particle/polymer interaction potential has spatial regularities with an average distance of three between neighboring minima. We present a model that exhibits how primitive molecular machines may convert the structural properties of the potential into locomotion regularities. On average, polymer movement takes place by shifts with long time intervals every three displacements. We argue that this feature is generic and lies at the origin of the three base codon composition.

Codon↗

A histochemical study of the biological effects of sodium dodecyl sulfate on the intestine of the gilthead seabream, Sparus aurata L.

This paper reports the morphological and histochemical changes caused by acute action of the detergent sodium dodecyl sulfate (SDS) on the intestine of the gilthead (Sparus aurata L.). Sixty-five giltheads were exposed to SDS concentrations of 5, 8.5, 10, and 15 mg/liter. Surface tensions were determined and the LC50 values calculated. The effects of SDS on the intestine were more pronounced in those specimens exposed to higher concentrations and for longer periods. Three causes of death were determined: (i) decrease in surface tension, (ii) destruction of tissue, and (iii) alteration of biomacromolecules. Both (ii) and (iii) were determined by histochemical techniques.

Animals↗

Morphological and histochemical changes in the liver and pancreas of gilthead, Sparus auratus L., induced by acute action of the anionic detergent, sodium dodecyl sulphate.

This paper reports the morphological and histochemical changes in the livers and pancreas of giltheads (Sparus auratus, L.) induced by acute action of the anionic detergent, sodium dodecyl sulphate (SDS). Sixty-five giltheads were exposed to SDS concentrations of 5, 8.5, 10 and 15 mg/l. The surface tension induced at each concentration was determined and the LC50 calculated. Morphological changes dependent on detergent concentrations and length of exposure were seen. Histochemical techniques showed alterations in carbohydrates and proteins, which may interfere with liver and pancreas function.

Animals↗

Glomerular lesions in the acquired immunodeficiency syndrome.

Between January 1982 and December 1983, 75 patients with the acquired immunodeficiency syndrome were identified in our hospitals: 35% used intravenous drugs, 50% had proteinuria in excess of 0.5 g/dL, and 10% were nephrotic. Glomerular changes seen at autopsy in 36 patients included frequent mesangial lesions and deposits associated with mild asymptomatic proteinuria. Focal and segmental glomerular sclerosis was found in 5 patients and 4 of these had the nephrotic syndrome. Whereas reversible episodes of acute renal failure were not uncommon, terminal episodes of acute renal insufficiency occurred in 14 patients. The short survival of these patients may prevent the development of chronic renal failure.

Acquired Immunodeficiency Syndrome↗

[Ascaris hepatic abscess].

An 18 months old infant with hepatic abscesses was studied. Ultrasonographic examination of the liver revealed 2 abscesses in the right lobe of the liver containing elongated hyperecogenic structures compatible with ascaris lumbricoides. Antibiotic and antihelmintic treatment was followed by complete clinical recovery.

Ascaridiasis↗