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1
artículo
Publicado 2011
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We study a system formed by M dimers through half-filled two-site Hubbard model, with two electrons. Our approach use the third version of Nonextensive Statistical Mechanics as tool for calculating thermodynamic and magnetic parameters such as entropy, internal energy, magnetization and specific heat. In the computer simulations, we vary the q entropic index values between 1 and 2, such that, q = 1.0, 1.4, 1.7 and 2.0. These values are interesting to study small magnetic systems. We find the critical temperature regions in simulations with the simple Hubbard model, i.e. without the intersite interaction. For other side, adding this additional term, we notice an enlargement and shifting of the thermodynamic parameters comparing with the obtained from simple Hubbard model; even more, we found in some cases the absence of the critical temperature regions.
2
artículo
Publicado 2005
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The search for microchannel wall modifications of simple use, that provide the desired functionality while the nonspecific adsorption is reduced to a mínimum, has allowed the development of new wall coatings. Specifically, the study of modifications that will enable to create robust microfluidic devices for the direct analysis of complex samples in which no sample pretreatment is required, are becoming a very important field of research, since they will allow microfluidic devices to become the analytical tool of choice for pharmaceutical and bioanalytical research fields.
3
artículo
Publicado 2005
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The search for microchannel wall modifications of simple use, that provide the desired functionality while the nonspecific adsorption is reduced to a mínimum, has allowed the development of new wall coatings. Specifically, the study of modifications that will enable to create robust microfluidic devices for the direct analysis of complex samples in which no sample pretreatment is required, are becoming a very important field of research, since they will allow microfluidic devices to become the analytical tool of choice for pharmaceutical and bioanalytical research fields.
4
artículo
Publicado 2021
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In Argentina, since March 2020, face-to-face classes have been suspended throughout the country, as a result of the COVID-19 pandemic. Therefore, the education system had to adapt to the distance education modality, and the universities were not the exception. In that transition, different problems emerged related to the didactics (organization, planning) but above all, access to ICT (New information and communication technology) and transmedia literacy. The ICT mediated education format deepened existing inequalities, that is, the material, social, educational, cultural, and psychological of family conditions. This article proposes a case study of the annual cathedra at the National University of Salta. It systematized the extended classroom experience in a previous pandemic period, where some tools like Classroom, a blog, and a Facebook page were used and later the use of virtual class...
5
artículo
Publicado 2021
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In Argentina, since March 2020, face-to-face classes have been suspended throughout the country, as a result of the COVID-19 pandemic. Therefore, the education system had to adapt to the distance education modality, and the universities were not the exception. In that transition, different problems emerged related to the didactics (organization, planning) but above all, access to ICT (New information and communication technology) and transmedia literacy. The ICT mediated education format deepened existing inequalities, that is, the material, social, educational, cultural, and psychological of family conditions. This article proposes a case study of the annual cathedra at the National University of Salta. It systematized the extended classroom experience in a previous pandemic period, where some tools like Classroom, a blog, and a Facebook page were used and later the use of virtual class...
6
artículo
Publicado 2022
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The objective of this investigation is to test the hypothesis of the possible association of one or more microsatellites located on 425-4933 with NSCLP. In this study a sample of 51 extended pedigrees were analyzed. From these pedigrees a sample of 51 caseparents trios was obtained. A novel genetic analysis was carried out using the Extended Transmission Disequilibrium Test (ETDT). Also a case control study was carried out with the 51 probands of the case-parents trios plus a sample of 94 controls of the Chilean population to test if differences were observed resulting from the methods used for the association studies. Microsatellites D4S1570, D4S1615, FGA, UCP1 and D4S1597 located in 4q were analyzed. The polymerase chain reaction (PCR) was used for analysis of DNA. Forward primers were marked with fluorescent-dye-label. Electrophoresis and analyses were carried out in an ABI PRISM 377 ...
7
artículo
This text is composed of 4 sections. In the first one, I recovered the emotive speech made by WilburSchramm about the first television broadcasting carried out on January 26th 1926 by John Logie Bairdin order to support the relevance of the term “Age of television”. The television is actually considered asthe emblematic media in the “Age of electricity”. In the second section, I studied the thesis developed byMarshall McLuhan about the so-called “shy giant”. At the beginning of 1960s, the television captivatedMarshall McLuhan. From a particular ecumenical perspective, the Canadian researcher believed thatthe television would restore the sensitive balance, thus favoring the transition to the “global village”. Asthe years went by, his optimism about the television started to vanish, and McLuhan adopted a morecritical position, similar to Neil Postman’s, against the televi...
8
artículo
This text is composed of 4 sections. In the first one, I recovered the emotive speech made by WilburSchramm about the first television broadcasting carried out on January 26th 1926 by John Logie Bairdin order to support the relevance of the term “Age of television”. The television is actually considered asthe emblematic media in the “Age of electricity”. In the second section, I studied the thesis developed byMarshall McLuhan about the so-called “shy giant”. At the beginning of 1960s, the television captivatedMarshall McLuhan. From a particular ecumenical perspective, the Canadian researcher believed thatthe television would restore the sensitive balance, thus favoring the transition to the “global village”. Asthe years went by, his optimism about the television started to vanish, and McLuhan adopted a morecritical position, similar to Neil Postman’s, against the televi...
9
artículo
Publicado 2021
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The aim of this study was to evaluate sodium caseinate (CS) in the dilution and freezing of bovine semen. Fifteen ejaculates from five bulls were diluted and then individually frozen using a diluent composed of tris-glycerol-citric acid with 8% v/v of low-density lipoproteins (LDL) and supplemented with CS in four treatments: CS 3% w/v (CS3), CS 4% w/v (CS4), CS 5% w/v (CS5) and without CS (Control). The mobility and kinetics (SCA® System) and the functional integrity of the membrane (HOS test) of the fresh, extended and thawed semen were evaluated. In addition, the morphology and vitality (eosin-nigrosin) of the fresh and extended semen, and the structural integrity of the membrane (SYBR14/IP), the acrosome integrity (FITC-PNA) and the in vitro fertilizing capacity (IVF) of thawed semen were evaluated. The statistical analysis of the sperm quality parameters was performed using linear ...
10
artículo
Publicado 2021
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Purpose. Fama–French model (FFM) has been successful in helping to predict the financial markets, but investors have been interested in creating more sophisticated models to better predict the performance of the stock market. The objective of the extended version is to create a more robust econometric model to better predict the performance of the Mexican Stock Market. Design/methodology/approach. The study divides the Mexican Stock Market into six different portfolios. The criteria to build those portfolios are the same one used in Fama–French (1992). The study comprises 78 stocks listed in the Mexican Stock Market that are analyzed monthly during 1997–2018. The study analyzes the period before and after the 2008–2009 financial crisis to identify whether there are important changes. The estimation applies the traditional and an extended version of the FFM that include macroecono...
11
artículo
A literature review is presented on the effects of school day extension programs implemented in various Latin American countries. According to their objects of interest, the studies are grouped into four types of impacts: a) school performance, b) academic and career paths, c) labor, and d) school organization and culture. A predominance of quantitative evaluations that analyzed the results in Mathematics and Language were identified, thus it was considered pertinent to broaden the knowledge search proposed from the programs. Other studies identified positive impacts on students' trajectories and their household economy; however, these results still need to be strengthened through similar studies in other contexts, which also inquire about the factors that explain these causes. Lastly, future studies should consider the particularities of each program in the search for their effects.
12
artículo
Objective: To study the presence in two hospitals of Lima of extended spectrum β-lactamases (BLEE) and to identify TEM and SHV types produced by Escherichia coli and Klebsiella pneumoniae strains. Material and Methods: The selection and confirmation of BLEE producing strains was done by antimicrobial susceptibility tests. The identification of bla TEM and bla SHV genes was achieved by polymerase chain reaction (PCR) and DNA sequencing. Results: One hundred and thirty seven Escherichia coli and 18 Klebsiella pneumoniae strains were isolated from hospitalized patients between July and September 2000. Most showed high resistance to third-generation cephalosporins and aztreonam;2,9% of all E.coli and 44,4% of all K.pneumoniae isolates were confirmed as BLEE producer strains. All BLEE producer strains were multidrug-resistant and most presented coresistance to trimethoprim/sulfamethoxazole, ...
13
artículo
Publicado 2024
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Introduction: Silver has been used since ancient times for its significant antibacterial potential that can be an effective alternative to combat antibiotic-resistant bacteria.. Objective: The objective was to evaluate the bactericidal activity of aqueous silver solution on strains of Escherichia coli and Klebsiella pneumoniae producing extended spectrum beta-lactamases (ESBL). Material and Methods: Experimental study with increasing stimulus, where 225 units of analysis were evaluated, consisting of 14 cultures of E. coli BLEE, 01 culture of Kl. pneumoniae BLEE, 5 concentrations of aqueous solution, with three applications per experiment. The electrochemical method was used to obtain the aqueous silver solution and its bactericidal activity was determined with the minimum bactericidal concentration. In addition, the growth curve of the bacterial strains was established by counti...
14
artículo
Publicado 2010
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The objective of the study was to evaluate the effects of two semen extenders: Tris- Fructose-egg yolk (Tris) and Citrate-Glucose-egg yolk (citrate) on motility and sperm membrane integrity (HOST) in ovine frozen semen in pellets. The study was carried out at the Semen Bank of the Agrarian University La Molina, in Lima, Peru, using 4 rams (2 Assaf and 2 Blackbelly) of 3.5 to 4 years old. A covariance analysis was used to evaluate the effect of the treatment and breed on Individual Progressive Motility (IPM), and randomized block design to evaluate the effect of extenders on sperm membrane integrity. Semen was frozen of dry ice and thawing was done in test tubes at 38 °C. In the Assaf breed, IPM of thawed semen was 63.77 and 61.11% when using Tris and citrate respectively, showing statistical difference (p<0.05). In the Blackbelly breed the IPM was 62.33 and 61.33%, when used Tris and...
15
artículo
REFRIGERATION OF CANINE SEMEN USING GLUCOSE, FRUCTOSE, TREHALOSE OR SUCROSE TO EXTEND SPERM SURVIVAL
Publicado 2010
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The effect of glucose, fructose, trehalose, and sucrose, as components of the extender, was evaluated on canine sperm viability during refrigeration at 5 ºC. The spermatic fraction of 16 dog ejaculations were distributed in 5 aliquots containing an extender based on Tris – citric acid – egg yolk, but differing in the presence of one of the sugars, plus a control without sugar. The five treatments were evaluated after 24, 48, 72, and 96 hours of refrigeration in relation to progressive motility and functional integrity of the membrane by the hypoosmotic swelling test (HOS). All groups, with the exception of the control group, the sperm motility maintained within acceptable ranges during the study (90% on day 0 and 60% on day 4). The integrity of the membrane remained slightly superior in groups with sugar (87-90%) in comparison with the control group (83-85%). The glucose and sucrose...
16
artículo
Publicado 2007
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The objective of the study was to evaluate the effect of three extenders and four combinations of two permeant and two non permeant cryoprotectant agents on the quality of post thaw ram semen. In Experiment 1, three extender were evaluated (A, B, and C) in order to select the best for the next step. In Experiment 2, different combinations of cryoprotectant agents were evaluated as follow: 1) Glycerol–Trehalose, 2) Glycerol– Sucrose, 3) Ethylene glycol-Trehalose, and 4) Ethylene glycol–Sucrose. In experiment 1, motility, viability and acrosomal integrity in extender A were higher than in extender B and extender C, and therefore, extender A was used for experiment 2. In this assay, motility, viability and acrosomal integrity, thermoresistance, and plasmatic membrane integrity were higher in groups Glycerol-sucrose and Glycerol-trehalose in comparison with groups Ethilene glycol-sucro...
17
artículo
Publicado 2011
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The study evaluated the performance of Tris-egg yolk and Citrate-egg-yolk asextenders for freezing ram semen in straws and the integrity of sperm membrane of frozensperm at the National Semen Bank – UNALM, Lima, Peru using six ram semen donors ofthree breeds. The semen was collected in an artificial vagina, diluted with Tris – glucose– quail egg yolk (Tris) or with Citrate – glucose – egg yolk (Citrate), stored in 0.5 mlpellets, and frozen in liquid nitrogen. Thawing was done at 38 ºC for 15 seconds. Inrefrigerated semen, the Progressive Individual Motility (PIM) in diluted semen with Tris was 82.3% and with Citrate was 79.2%, and the integrity of the cytoplasmic membrane(HOST) was 78.0 ± 4.4 with Tris and 73.2 ± 5.8% with Citrate. In thawed semen, PIM was62.0 and 56.8%, and HOST was 49.8 ± 3.9 and 41.3 ± 3.8% for Tris and Citrate respectively,with significant differences ...
18
artículo
Publicado 2011
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The study evaluated the performance of Tris-egg yolk and Citrate-egg-yolk asextenders for freezing ram semen in straws and the integrity of sperm membrane of frozensperm at the National Semen Bank – UNALM, Lima, Peru using six ram semen donors ofthree breeds. The semen was collected in an artificial vagina, diluted with Tris – glucose– quail egg yolk (Tris) or with Citrate – glucose – egg yolk (Citrate), stored in 0.5 mlpellets, and frozen in liquid nitrogen. Thawing was done at 38 ºC for 15 seconds. Inrefrigerated semen, the Progressive Individual Motility (PIM) in diluted semen with Tris was 82.3% and with Citrate was 79.2%, and the integrity of the cytoplasmic membrane(HOST) was 78.0 ± 4.4 with Tris and 73.2 ± 5.8% with Citrate. In thawed semen, PIM was62.0 and 56.8%, and HOST was 49.8 ± 3.9 and 41.3 ± 3.8% for Tris and Citrate respectively,with significant differences ...
19
tesis de grado
Publicado 2023
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Market basket analysis provides an insight into customer consumption patterns and trends in the industry. These will be achieved by analyzing and studying the performance of the large datasets of transactions made by consumers held in retail stores. These commercial transactions will be analyzed using the Machine Learning technique called the A priori algorithm by establishing association rules and determining those groups of items in a market basket whose association could represent better economic benefits for companies. This study will analyze the historical sales data of the product groups, in order to identify relationships that al-low companies in the sector to generate patterns to propose the increase of their portfolio based on the products with the greatest purchasing trends. At the end of this investigation, commercial strategies will be proposed to improve sales, take advantag...
20
artículo
Publicado 2018
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Introducción. El aumento de las tasas de resistencia en bacterias uropatógenas y su propagación se han convertido en un problema de salud pública a nivel mundial, cobrando mayor importancia la diseminación de aislamientos resistentes productores de ß-lactamasas de espectro extendido, resultando útil la caracterización molecular de plásmidos y otros elementos genéticos de las bacterias para establecer la relación genética que existe entre ellas y tener datos relevantes que puedan sugerir la dirección de propagación de este tipo de resistencia. El objetivo de nuestra investigación fue determinar los perfiles plasmídicos en aislamientos de Escherichia coli y Klebsiella pneumoniae productoras de ß-lactamasas de espectro extendido de urocultivos del Instituto Nacional de Salud del Niño, Lima, Perú. Métodos. Estudio descriptivo, observacional de corte transversal. Resultado...
