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Search Results: 1 - 10 of 32354 matches for " Ana Canepa Saenz "
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Quality Function Deployment (QFD) House of Quality for Strategic Planning of Computer Security of SMEs
Jorge A. Ruiz-Vanoye,Ocotlán Díaz-Parra,Juan Arturo Nolazco-Flores,Ana Canepa Saenz
International Journal of Combinatorial Optimization Problems and Informatics , 2013,
Abstract: This article proposes to implement the Quality Function Deployment (QFD) House of Quality for strategic planning of computer security for Small and Medium Enterprises (SME). The House of Quality (HoQ) applied to computer security of SME is a framework to convert the security needs of corporate computing in a set of specifications to improve computer security.
The role of catalysis on the formation of an active proto-enzyme in the prebiotic aqueous environment  [PDF]
Carlo Canepa
Natural Science (NS) , 2013, DOI: 10.4236/ns.2013.55069
Abstract: A model detailing the conditions for the formation of active enzymes from amino acid monomers in the pre-biotic aqueous environment is proposed, making use of only a minimal number of parameters: the intensity of the amino acid source and the experimental rate coefficient for polypeptide hydrolysis. In a closed system with fixed total amino acid concentration, the formation of polypeptides of significant length is precluded by hydrolysis. In the presence of an amino acid source, the behavior of the steady state solutions is dependent on the efficiency of the catalytic activity in the environment. In absence of catalysis the formation of long amino acid chains shows a remarkable similarity to the equilibrium problem, i.e. it is equally unlikely that an active protein forms. In the presence of catalysis the concentration of polypeptides of significant length increases dramatically to about the same order of magnitude as the steady state concentration of the monomers. Besides the important notion of the proto-enzyme concentration, the model offers a link between the given environmental conditions (flux of monomers, rates of the peptide bond formation and hydrolysis, size of the amino acid set) and properties of the polypeptide relevant to its catalytic properties, such as its length and conserved number of residues.
The Effect of Radiogenic Heating on the Amino Acid Content of an Early Cometary Body  [PDF]
Carlo Canepa
International Journal of Astronomy and Astrophysics (IJAA) , 2013, DOI: 10.4236/ijaa.2013.33033

This study compares the rates for the formation and destruction of amino acids in the liquid cometary core subjected to radiogenic heating by the β+ decay of the cosmogenic nuclide 26Al. The evolution of the temperature and mass of the comet were computed along with the dynamics of relatively complex organic species such as amino acids. Given the experimentally determined rate coefficient for the radiolysis of amino acids in water solution, the destruction of amino acids is virtually completed after an absorbed radiation dose of ~1 kGy. The calculations suggest that the liquid water core in comets with an initial radionuclide abundance that is sufficient to crystallize and melt the original amorphous ice is subjected to a dose of 100 - 1500 kGy. Any amino acid concentration formed in water either by radiolysis of simpler compounds or by thermal processes such as the synthesis of Strecker could not survive the irradiation delivered by the decay of 26Al.

A potential energy profile of the catalytic cycle of pyruvate decarboxylase  [PDF]
Cristinenrichetta Borriglione, Carlo Canepa
Natural Science (NS) , 2012, DOI: 10.4236/ns.2012.411116
Abstract: A computational study on the mechanism for the decarboxylation of pyruvic acid to acetaldehyde catalyzed by pyruvate decarboxylase at the B3LYP/6-31G (d, p) level of theory is presented. The model employed is self-contained and it does not resort to external groups to provide protons to the various structures in the mechanism. The potential energy surface points at the intramolecular proton transfer from the amino group of the pyrimidine ring in the enamine intermediate to the enol exocyclic carbon as the rate-determining step (with a barrier of 20.55 kcal·mol–1). This value is in reasonable agreement with an estimated barrier of 24.76 kcal·mol–1, derived from the experimental rate constant (4.0 10–5 s–1) for the decarboxylation of α-lactylthiamin.
On the curvature in logarithmic plots of rate coefficients for chemical reactions
Carlo Canepa
Chemistry Central Journal , 2011, DOI: 10.1186/1752-153x-5-22
Abstract: Curvatures in logarithmic plots of enzyme-catalyzed reactions were detected and discussed as early as 1949 by Kistiakowsky and Lumry [1] in a paper on the hydrolysis of urea by urease, and described as widespread by Maier and Tappel [2] in 1955. Among the many examples of curved Arrhenius plots known for enzyme-catalyzed processes are the cleaving of RNA by deoxyribozyme [3], the activation of spinach chloroplast fructose-1,6-biphosphatase [4], the catalytic activity of urocanase from Pseudomonas putida [5], adenylate cyclase from Saccharomyces cerevisiae [6], turnip peroxidase, bovine intestinal phosphatase [2], the kinetics of Shiff base formation between a cholesterol ozonolysis product and dimyristoyl phosphatidyl ethanolamine [7], the activity of cyanobacterial ADP-glucose pyrophosphorylase from Anabaena [8], and the hydrolysis of various amides catalyzed by α-chymotrypsin [9]. Among the explanations put forward to rationalize the observed curvature are the temperature-induced conformational change in the reactant [10], the assumption that the measured rate coefficient actually is a combination of elementary rate coefficients for a multiple-step reaction [6], or the notion that the derivative of ΔHTS with respect to temperature is negative, i. e. [11]. The curvature of lnkr versus 1/T is thus viewed as a result of a more complex microscopic mechanism in turn composed of individual elementary steps that do follow Transition State Theory (TST) behavior. The shortcomings of TST have been discussed by Pineda and Schwartz [12], who describe promoting vibrations coupled to the reaction coordinate. While their computational analysis spans a time scale of tens of picosecond [13], this work focuses on the low-frequency, long-range motions of the whole protein on a time scale of up to one second for α-chymotrypsin. The link between enzyme dynamics and hydrogen-transfer reactions was also discussed by Knapp and Klinman [14] in the context of the environmentally coupled hy
El desierto como basurero en El alemán de Atacama de Roberto Ampuero: ecoliteratura en los tiempos de globalización
Gina Canepa
Polis : Revista de la Universidad Bolivariana , 2007,
Abstract: El desarrollo creciente de la novela negra neo-detectivesca en Chile es una prueba más de que atravesamos por un cambio artístico fundamental. Tecnológica y estéticamente impecables, las variantes de esta novela suelen ser producidas por escritores rigurosamente profesionales. Sin embargo y a pesar de los factores mencionados, ésta no está exenta de popularidad y éxito de ventas. El alemán de Atacama de Roberto Ampuero es la segunda de la saga de su detective ficcional Cayetano Brulet. Como otras de sus novelas, ésta conlleva una reflexión sobre el entreguismo de la nación-estado, los efectos devastadores de la economía global, la precariedad de los grupos étnicos y la destrucción ecológica.
Calendario tradicional peruano
Gisela Canepa
Anthropologica , 2003,
Search for the associated production of chargino and neutralino in the final state with three leptons
Anadi Canepa
Physics , 2006,
Abstract: Supersymmetry, if realized in Nature, predicts the existence of new particles, as chargino and neutralino, which might manifest themselves with peculiar signatures. Three leptons and large missing transverse energy in the event could signal their associated production. We report the latest results of the search performed by the CDF Collaboration in proton-antiproton collisions at Tevatron Run II.
Implementation and evaluation of a National External Quality Control Program for Cervical Cytology in Mexico
Flisser Ana,García-Malo Felipe,Canepa María de los Angeles,Doncel Susana
Salud Pública de México , 2002,
Abstract: Objective. To evaluate cytology laboratories and the performance of cytotechnologists for establishing efficient external quality control for Mexico's National Program for the Prevention and Control of Cervical Cancer. Material and Methods. During January and February 1998, an on-site evaluation of all cytology laboratories of the Ministry of Health found that only 70% of the microscopes were in adequate working conditions, reagents were out of date, and working conditions were sub-optimal. A program for external quality control based on proficiency testing was established for cytotechnologists. Fifty slide sets with 20 Papanicolaou slides and 10 photographic slides were prepared. The sets were given to the cytotechnologists for evaluation and again one year later by courier. Results. Twenty-one percent of microscopes were repaired and 9% replaced; reagents were distributed and laboratory facilities improved. Only 16% of cytotechnologists passed the initial proficiency test. Cytotechnologists received a refresher training course: one year later 67% of them passed the proficiency test. To ascertain that each slide was correctly diagnosed, 41 sets were rescreened by expert cytopathologists or cytologists and their diagnoses compared to the original ones. Thirty-seven sets had 86% to 96% concordance. Conclusions. This new system for external quality control of cervical cytology allowed the opportune and reliable evaluation of the performance of cytotechnologists.
Linfoma de células en anillo de sello que simula carcinoma mucosecretante
Saenz de Chirife,Ana María; Rojas Bilbao,Erica; Gimenez,Liliana; Marino,Lina; Celeste,Francisco;
Medicina (Buenos Aires) , 2004,
Abstract: signet ring cell lymphoma is a rare neoplasm caracterized by large, vacuolated and clear cells mimicking mucin-producing adenocarcinoma. it is localized in nodal and extranodal sites. a case of a 59 years old male, with a diffuse lymphoma signet ring cell type localized on oropharingeal mucosa is reported. the histopathology study showed signet ring cells and the immunophenotype was: vimentine(+), cd45(+), cd20(+), ig m(+), kappa chain(+) and high index proliferative activity of neoplastic cells (ki 67:70%). after a review of the literature and previous reports, we could not find a similar case in this anatomic site. the patient had a unfavourable clinical course and died two months after the diagnosis without receiving any treatment.
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