In-vitro evaluation of different antimicrobial combinations with and without colistin against carbapenem-resistant acinetobacter baumannii

Carbapenem-resistant Acinetobacter baumannii (CR-Ab) infections are associated with high morbidity and mortality. The aim of the study was to evaluate the in-vitro activity of different antimicrobial combinations (with and without colistin, COL) against clinical isolates of CR-Ab collected from patients with CR-Ab infection, including unconventional combinations such as COL + VANcomycin (VAN) and COL + rifampin (RIF). CR-Ab strains were collected from hospitalized patients at Sapienza University of Rome. Antimicrobial susceptibility patterns were determined throughout MIC50/90s whereas the synergistic activity was evaluated by qualitative (i.e., checkerboard) and quantitative (i.e., killing studies) methods. All the strains were found oxacillinase (OXA) producers and tigecycline (TIG) sensitive whereas 2 strains were resistant to COL. Application of the checkerboard method indicated complete synergism in COL combinations at different extension: 21.4%, 57.1%, 42.8%, 35.7% for COL + meropenem (MEM), COL + RIF, COL + VAN and COL + TIG, respectively, with the non-conventional combinations COL + VAN and COL + RIF exhibiting the highest rate of synergism. Regarding COL-free combination, complete synergism was observed in 35.7% of the strains for MEM + TIG. Killing studies showed that the combinations COL + MEM, COL + TIG and MEM + TIG were bactericidal and synergistic against both colistin-sensitive and low colistin-resistant strains whereas only the combinations COL + VAN and COL + RIF showed an early and durable bactericidal activity against all the tested strains, with absence of growth at 24 h. This study demonstrated that COL-based combinations lead to a high level of synergic and bactericidal activity, especially COL + VAN and COL + RIF, even in the presence of high level of COL resistance

Publicidad : Medición de Rating

La presente investigación de carácter bibliográfico tiene como tema La publicidad como parte de los ejes de investigación del departamento de administración de empresas de la facultad de ciencias económicas de la UNAN Managua y su subtema la medición del rating. Se tiene como objetivo general determinar la medición del rating a través de conceptos básicos y cálculos de rating. La base que alimenta este informe se hace énfasis en cuatro capítulos tales como generalidades de la publicidad, medición de rating, conceptos básicos de medios para medición y cálculo de rating y por ultimo definiciones básicas en la planeación de medios. Las técnicas que fueron utilizadas para desarrollar este informe fueron principalmente la lectura y la recolección de documentación bibliográfica basado en la publicidad y la medición de rating, así mismo la tabulación del informe se hará aplicando las normas APAs 6 de Javeriano. Los resultados o presentación del informe está basado en la normativa de presentación de seminario de graduación plan 2013 de la UNAN Managua. Los principales términos descriptores de este informe, son la introducción, justificación, objetivos del informe, desarrollo de capítulos, conclusiones y bibliografía

A theoretical approach to the O(1D) + H2O (X1A1) reaction: ab initio potential energy surface and quasiclassical trajectory dynamics study

An ab initio study of the ground potential energy surface (PES) of the O(1D)+CH4→OH+CH3 reaction has been performed using the second and fourth order Møller-Plesset methods with a large basis set. From the ab initio data a triatomic analytical ground PES with the methyl group treated as an atom of 15.0 amu has been derived. This PES has been employed to study the dynamics of the reaction by means of the quasiclassical trajectory (QCT) method. A good agreement between the experimental and QCT OH rovibrational distributions at a collision energy of 0.212 eV with the methane molecule at 298 K has been obtained. The analysis of the microscopic reaction mechanism shows that the reaction takes place almost exclusively through the insertion of the O(1D) atom into a C-H bond, due to the presence of the deep (CH3)OH minimum, and the resulting trajectories may be direct or nondirect (short-lived collision complexes mainly) with about the same probability. The OH vibrational distribution arising from the direct mechanism is inverted, while the nondirect mechanism leads to a noninverted one. There is some tendency to give broader OH rotational distributions peaking at higher N′ values, particularly for the vibrational levels v′ = 0-1, in the case of the nondirect trajectories. The PES derived here may be used in dynamics studies under conditions where the methyl group motions are not strongly coupled to the motions leading to reactio

Ab initio CASPT2//CASSCF study of the O(1D) + H2O(X1A1) reaction

The ground potential energy surface (PES) of the O(1D) + H2O system was studied with the CASPT2//CASSCF ab initio method. We analyzed the degree of validity of an earlier ab initio study by us that used the Møller-Plesset (MP) method. Both the present CASPT2//CASSCF calculations and the highest level MP calculations [PUMP4//UMP2] showed that the main reaction channel (OH + OH) has no energy barrier along the minimum energy path. This result is consistent with the absence of experimental activation energy. The CASPT2//CASSCF and PUMP4//UMP2 results, however, show important differences, mainly concerning the energy, due to the dominant open-shell singlet character of the ground PES. To make an accurate general description of this system, ab initio calculations using multireference methods like the one discussed here are required. Nevertheless, the earlier PUMP4//UMP2 calculations can be taken as a reasonable starting point for characterizing the ground PES of this system. Moreover, the pseudotriatomic (O(1D) + H-(OH)) analytical potential energy surface derived in the previous work to interpret the experimental resultsis a reasonable model for describing the O(1D) + H2O → 2OH reaction

New analytical (2A',4A') surfaces and theoretical rate constants for the N(4S) + O2 reaction

We report two new analytical fits of the ground potential energy surface (PES) (2A') and the first excited PES (4A') involved into the title reaction and its reverse, using ab initio electronic structure calculations from papers I and II along with new grids of ab initio points by means of the Second-Order Perturbation Theory on CASSCF wave function (CASPT2 (17,12) G2/aug-cc-pVTZ) reported here (1250 points for the 2A' PES and 910 points for the 4A' PES). Some experimental data were also introduced to better account for the exoergicity and the experimental rate constant at 300 K. The final root-mean-square deviations of the fits were 1.06 and 1.67 kcal/mol for 2A' and the 4A' PESs, respectively, for the NOO Cs-abstraction and insertion regions of the PESs. Thermal rate constants were calculated (300-5000 K) for both the direct and reverse reactions by means of the variational transition state theory with the inclusion of a microcanonical optimized multidimensional tunneling correction, obtaining a very good agreement with the experimental data within all the temperature range. The new analytical 2A' PES presents several stationary points not introduced in previous analytical surfaces, and describes accurately the NO2 (X 2A1) minimum, which seems to be very accessible according to the trajectories run in a preliminary quasiclassical trajectory study. The new analytical 4A' PES has a lower energy barrier than the previous one, which increases significantly the contribution of this PES to the total rate constant at high temperatures. Moreover, the new analytical PESs not only describe accurately the Cs-regions of the NOO system but also the ONO C2v- or near C2v-regions

The lowest doublet and quartet potential energy surfaces involved in the N(4S) + O2 reaction. II. Ab initio study of the C2v-symmetry insertion mechanism

In the present work we have carried out ab initio complete active space self-consistent field (CASSCF) and second-order perturbation theory on CASSCF wave function (CASPT2) calculations and also some density functional theory calculations with the aug-cc-pVTZ Dunning's basis set on the lowest A1, B1, A2 and B2 doublet and quartet potential energy surfaces (PESs) that could be involved in the title reaction. Thus, several minima, transition states and surface crossings have been found for the C2v-insertion reaction mechanism. The results agree very well with available experimental data (i.e., for NO2 (2A1), MIN2 (2B2), NO2 (2∏u)) and with other previous ab initio calculations. Six A' / A' and four A' / A' type surface crossings were located and classified for these PESs, whose only one (i.e., 2B2 / 2A1) has been previously reported in theoretical and experimental studies. High-energy barriers were found for the direct C2v-insertion mechanism (3.11 and 2.54 eV for the lowest doublet and quartet PESs at the CASPT2/aug-cc-pVTZ level, respectively), clearly showing that this competitive mechanism is much less favorable than the direct Cs-abstraction or the indirect Cs-insertion reaction mechanisms reported in paper I

Desarrollo de la estrategia de posicionamiento on-line para la comercialización de maquinarias agrícolas en la región centro de Argentina

Tesis (Maestría en Dirección de Negocios)El presente trabajo de aplicación tiene por objeto plantear el desarrollo de una estrategia de posicionamiento on-line para la comercialización de maquinarias agrícolas en la región centro de la República Argentina de la empresa Monte Maíz Maquinarias. El servicio de venta que se pretende ofrecer con el desarrollo de esta estrategia mediante la utilización de herramientas de posicionamiento on-line disponibles, está especialmente dirigido al segmento de productores agropecuarios y contratistas rurales. El mercado de las maquinarias agrícolas es el principal segmento de la industria Argentina de bienes de capital con altos niveles de tecnología de procesos y productos, existe un alto compromiso con el sector por parte de los empresarios y la mano de obra empleada es altamente calificada. Cabe aclarar, que el mercado de maquinarias agrícolas se encuentra estrechamente vinculado a la estacionalidad de los cultivos, produciendo variaciones en la demanda según la época estacional que se encuentre. Por lo expuesto, este proyecto surge de una necesidad insatisfecha por parte de los usuarios del mercado de la maquinaria agrícola, ya que, en general la mayoría de las opciones disponibles para su adquisición se encuentran distantes entre sí.Fil: Oliva, Ana Carolina. Universidad Nacional de Córdoba. Facultad de Ciencias Económicas; Argentina

Size of Vesicle Pools, Rates of Mobilization, and Recycling at Neuromuscular Synapses of a Drosophila mutant, shibire

AbstractTwo vesicle pools, readily releasable (RRP) and reserve (RP) pools, are present at Drosophila neuromuscular junctions. Using a temperature-sensitive mutant, shibirets, we studied pool sizes and vesicle mobilization rates. In shibirets, due to lack of endocytosis at nonpermissive temperatures, synaptic currents continuously declined during tetanic stimulation until they ceased as the result of vesicle depletion. By then, ∼84,000 quanta were released. Vesicles were mobilized from RP at a rate 1/7–1/10 of RRP. Cytochalasin D inhibited mobilization of vesicles from RP, allowing us to estimate the size of RRP as 14%–19% of all vesicles. Vesicle recycling supports synaptic transmission during prolonged tetanic stimulation and the maximum recycling rate was 1000 vesicles/s

Poetics of the Excess: Digital Aesthetics in the Twitterbot Cumatron

En las últimas décadas hemos observado grandes transformaciones en las formas de producción, circulación y recepción de la cultura, a partir del lugar central que han adquirido las tecnologías digitales en lo que podemos identificar como un nuevo régimen de producción cultural y estético. En este marco hemos visto desarrollarse, desde fines de los noventa, el creciente campo de la literatura digital en América Latina. En la investigación que he llevado a cabo se pueden distinguir dos ámbitos de creación: uno que experimenta con el lenguaje de código a través del ejercicio de programación, en el cual encontramos hipertextos, hipermedias, literaturas generativas, poesía de código, literatura interactiva, entre otras; y otro ámbito que experimenta con el medio y, por lo tanto, saber programar no es un requisito fundamental para poder crear. En este ámbito encontramos la tuiteratura, instapoesía, narrativas en WhatsApp, y toda clase de memes y bots poéticos en redes sociales. En el campo de la literatura digital, aquella que experimenta con el medio ha proliferado en los años recientes y, al mismo tiempo, ha sido la más atacada desde los defensores de ciertos criterios de calidad literaria. Paradójicamente, este tipo de literatura ha sido también la menos estudiada, por lo que aquellos que defienden la calidad literaria no se cuestionan los criterios y supuestos que la definen, y que quizás no son aplicables a las literaturas digitales en sus diversos formatos. Esta literatura constituye una poética del exceso: prolifera en las redes sociales y se entrelaza con la lógica de la obsolescencia, la repetición y la apropiación, lo que la vuelve difícil de aprehender. Su aparición relativamente reciente y sus características efímeras constituyen, quizás, algunas de las razones por las cuales ha recibido menos atención en el campo de la literatura digital latinoamericana. En este artículo analizaré el bot poético «Cumatron» del colectivo chileno Cyberpunga, para identificar en esta escritura maquínica unas posibles estéticas digitales, lenguajes y poéticas digitales que se desarrollan en esta forma de escritura en 280 caracteres. Este trabajo nos permitirá, además, situar este tipo de escrituras en la discusión latinoamericana sobre las prácticas creativas en la literatura y cultura digitales, sus particularidades y tensiones.In recent decades we have observed major transformations in the forms of production, circulation, and reception of culture, based on the central place acquired by digital technologies in what we can identify as a new regime of cultural and aesthetic production. In this framework we have seen the development, since the late nineties, of the growing field of digital literature in Latin America. In the research I have carried out, two fields of creation can be distinguished: one that experiments with code language through programming, where we find hypertexts, hypermedia, generative literatures, code poetry, interactive literature, among others; and the other that experiments with the medium, where programming is not a requisite. In this domain we find tuiterature, instapoetry, narratives in WhatsApp, and all kinds of memes and poetic bots in social networks. In the field of digital literature, that which experiments with the medium has proliferated in recent years and, at the same time, has been the most attacked by the defenders of certain criteria of literary quality. Paradoxically, this type of literature has also been the least studied, so that those who defend literary quality do not question the criteria and assumptions that define it, and that perhaps are not applicable to digital literatures in their various formats. This literature constitutes a poetics of excess: it proliferates in social networks and is intertwined with the logic of obsolescence, repetition, and appropriation, which makes it difficult to understand. Literature that experiments with the medium constitutes a poetics of excess: it proliferates in social networks and is intertwined with the logic of obsolescence, repetition, and appropriation, which makes it difficult to apprehend. Its relatively recent appearance and its ephemeral characteristics are, perhaps, the reasons why it has received less attention in the field of Latin American digital literature. In this article I will analyze the poetic bot «Cumatron» by the Chilean collective Cyberpunga, to identify in this machinic writing some possible digital aesthetics, languages, and digital poetics that are developed in this form of writing in 280 characters. This work will also allow us to situate this type of writing in the Latin American discussion on creative practices in digital literature and culture, its particularities, and tensions.Este artículo forma parte del Proyecto Proyecto Fondecyt Regular N.° 1180771 «Cartografía crítica de la literatura digital latinoamericana» (2018-2021), financiado por ANID (Agencia Nacional de Investigación y Desarrollo)