332 research outputs found

    Evaluation of the presence of Vibrio parahaemolyticus in white shrimp (Litopenaeus vannamei) estuarine-wild from southern Sinaloa and northern Nayarit by microbiological analysis and PCR

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    Given the incidence of human poisonings attributed to raw shrimp consumption in southern of Sinaloa and northern of Nayarit in recent years, white shrimp (Litopenaeus vannamei) was sampled from three wildestuaries where it’s been captured and one sample was taken from a sale center in order to determine the possible presence of toxigenic Vibrio parahaemolyticus, from May to December of 2012. Samples were analyzed by Biochemical test and Polymerase Chain Reaction (PCR), they were also tested for the specific an toxicological identification, using molecular oligo nucleotides markers tlh, tdh and trh. The number of positives results were recorded to a table of most probable number (MPN).The number of samples positive for V. parahaemolyticus, weren’t toxigenic and it was demonstrated that they were below the limit established in the Mexican Official Standard NOM-242-SSA1-2009. In conclusion, the present study revealed that consumption of raw shrimp from the dates and sites sampled did not show to be a risk for human gastrointestinal diseases

    Vallerand´s model in Asturian adolescents: Implementation and development

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    Se examinó la secuencia del modelo de Vallerand (1997) en el contexto de la educación física: Los factores sociales influyen en los mediadores psicológicas, que a su vez predicen los tipos de motivación, que dan lugar a determinadas consecuencias. Tomando como base el Modelo de Vallerand y el estudio empírico de Ntoumanis (2001), este trabajo se propuso comprobar el modelo completo en todas sus secuencias con una muestra de estudiantes adolescentes asturianos (N=507) de una franja de edad más amplia (12-17 años), incluyendo como factor social una subdimensión distinta al trabajo original (papel importante) e introduciendo dos nuevas consecuencias motivacionales (diversión y grado de presión percibida). Se administraron versiones españolas de diversos cuestionarios: PMCSQ-2, BPNES, PLOC, IMI (diversión, esfuerzo percibido y presión percibida) y consecuencias motivacionales (aburrimiento e intención de práctica). El análisis factorial confirmatorio reveló que los datos se ajustaban bien al modelo, y que las tres necesidades psicológicas mediaban entre el clima de tarea y la motivación intrínseca. Ésta predijo positivamente la diversión, el esfuerzo e intención de práctica, y negativamente, el aburrimiento. La competencia percibida resultó el predictor más fuerte, influyendo positivamente en la motivación más autónoma y, negativamente, en la más controlada. La desmotivación predijo positivamente el aburrimiento y la presión y, negativamente, el esfuerzoThe complete sequence of Vallerand’s model (1997) was examined in the context of physical education: Social factors influence the psychological mediators, which in turn predicted motivation types, which lead to certain consequences. Based on the Vallerand´s Model and Ntoumanis (2001) empirical study, this investigation was undertaken to test the full model in all sequences with a sample of Asturian adolescents students (N = 507) of a wider age range (12 -17 years), including as a social factor a distinct sub-dimension to the original work (relevant role) and introducing two new motivational consequences (fun and degree of perceived pressure). The Spanish validated version of these questionnaires was used: PMCSQ-2, BPNES, PLOC, three subscales of IMI (enjoyment, effort, and competence) and other motivational outcomes such as boredom and future sport participation. Results from the Confirmatory Factor Analysis showed that the data fit the model proposed, and the three psychological needs mediated between the task climate and the intrinsic motivation. This positively predicted enjoyment, effort and future sport participation, and negatively boredom. Competence was the stronger predictor, positively influencing the most autonomous types of motivation, and negatively the more controlled ones. Amotivation positively predicted boredom and pressure, and negatively, effortEste estudio se ha realizado en el marco del proyecto de I+D+I número DEP2012- 31997, subvencionado por el Ministerio de Economía y Competitivida

    Chaotic Electron Motion in Superlattices. Quantum-Classical Correspondence of the Structure of Eigenstates and LDOS

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    We investigate the classical-quantum correspondence for particle motion in a superlattice in the form of a 2D channel with periodic modulated boundaries. Its classical dynamics undergoes the generic transition to chaos of Hamiltonian systems as the amplitude of the modulation is increased. We show that for strong chaotic motion, the classical counterpart of the structure of eigenstates (SES) in energy space reveals an excellent agreement with the quantum one. This correspondence allows us to understand important features of the SES in terms of classical trajectories. We also show that for typical 2D modulated waveguides there exist, at any energy range, extremely localized eigenstates (in energy) which are practically unperturbed by the modulation. These states contribute to the strong fluctuations around the classical SES. The approach to the classical limit is discussed.Comment: 4 pages, 4 figure

    Effect of high-pressure processing of Atlantic mackerel (Scomber scombrus) on biochemical changes during commercial frozen storage

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    This research focuses on biochemical changes related to quality losses observed in Atlantic mackerel (Scomber scombrus) muscle stored under commercial frozen storage conditions (9 months, −18 °C) when subjected to highhydrostatic pressure (HHP) treatments (125, 150, 175, and 200 MPa for 0 min) before freezing. After freezing, free fatty acid (FFA) formation (lipid hydrolysis assessment) showed a marked inhibition in HHP-treated fish and during frozen storage of samples treated at 175 MPa. Fluorescence ratio (FR) assessment of tertiary lipid oxidation showed a partial inhibitory effect during the 0–9-month period for samples treated at 175 and 200 MPa. After a 3-month storage of samples treated at these pressure levels, one-dimensional SDS-PAGE analysis of the sarcoplasmic protein fraction revealed the disappearance of a band; additionally, samples treated at 150 MPa showed the same effect at month 9. After gel excision, trypsin digestion, tandem mass spectrometry (MS/MS), and sequence database analysis, the band was identified as phosphoglycerate mutase 2 (28.7 kDa). On the other hand, HHP processing did not show a significant effect on trimethylamine (TMA) values, primary and secondary lipid oxidation, PUFA levels, 1-D myofibril protein pattern, and the activity of acid phosphatase and cathepsins B and D. Biochemical quality indices such as FFA, TMA, and FR and the activity of acid phosphatase and cathepsin B showed a progressive increase throughout the frozen storage of all samples

    Lipid and protein changes related to quality loss in frozen sardine (Sardina pilchardus) previously processed under high-pressure conditions

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    This research focuses on biochemical changes related to quality loss in frozen (−18 °C for 9 months) sardine (Sardina pilchardus) previously subjected to high-pressure (HP) processing (125–200 MPa). The inhibition (p < 0.05) of lipid hydrolysis development (lower free fatty acid formation and lipase activity), observed in frozen sardine as a result of the previous HP treatment, increased with the pressure level applied. Several parameters including peroxide value, thiobarbituric acid index, fluorescent compounds, and polyenes showed that the applied HP conditions prior to sardine freezing did not increase lipid oxidation. Also, HP did not induce a substantial modification of acid phosphatase and cathepsins B and D activities, and the electrophoretic patterns of sarcoplasmic and myofibrillar protein fractions did not change. However, HP processing led to a decrease in myofibrillar protein content in frozen pressure-treated fish, an effect that was higher in 175- and 200-MPa treated samples. In conclusion, this research showed that pressure treatments in the 125–200- MPa range with holding time of 0 min cause only minor modifications in biochemical indicators of deterioration throughout the subsequent frozen storage of samples for up to 9 months. This study shows the need to optimize HP conditions, particularly in the case of applications combining HP treatments, frozen storage, and thawing to obtain products with high quality and commercial viability

    Quantum-classical correspondence for local density of states and eigenfunctions of a chaotic periodic billiard

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    Classical-quantum correspondence for conservative chaotic Hamiltonians is investigated in terms of the structure of the eigenfunctions and the local density of states, using as a model a 2D rippled billiard in the regime of global chaos. The influence of the observed localized and sparsed states in the quantum-classical correspondence is discussed.Comment: 8 pages, 4 figure

    Spectral and localization properties of random bipartite graphs

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    Bipartite graphs are often found to represent the connectivity between the components of many systems such as ecosystems. A bipartite graph is a set of n nodes that is decomposed into two disjoint subsets, having m and n-m vertices each, such that there are no adjacent vertices within the same set. The connectivity between both sets, which is the relevant quantity in terms of connections, can be quantified by a parameter a ¿ [0, 1] that equals the ratio of existent adjacent pairs over the total number of possible adjacent pairs. Here, we study the spectral and localization properties of such random bipartite graphs. Specifically, within a Random Matrix Theory (RMT) approach, we identify a scaling parameter ¿ = ¿(n, m, a) that fixes the localization properties of the eigenvectors of the adjacency matrices of random bipartite graphs. We also show that, when ¿ 10) the eigenvectors are localized (extended), whereas the localization–to–delocalization transition occurs in the interval 1/10 < ¿ < 10. Finally, given the potential applications of our findings, we round off the study by demonstrating that for fixed ¿, the spectral properties of our graph model are also universal

    Higgs triplet effects in purely leptonic processes

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    We consider the effect of complex Higgs triplets on purely leptonic processes and survey the experimental constraints on the mass and couplings of their single and double charge members. Present day experiments tolerate values of the Yukawa couplings of these scalars at the level of the standard electroweak gauge couplings. We show that the proposed measurement of the ratio R_{LCD}=\sigma (\nu_{\mu}e)/ [\sigma (\bb\nu_{\mu}e) + \sigma (\nu_e e )] would allow to explore a large region of the parameter space inaccessible to the usual ratio R=\sigma (\nu_{\mu}e)/\sigma (\bb\nu_{\mu}e).Comment: 14 pages, LaTeX, Three figures included using uufiles. A postscript version is available at ftp://ftp.ifae.es/preprint/ft/uabft378.p

    Experiencia en el tratamiento quirúrgico del angiofibroma nasal juvenil en Hospital de Especialidades No 2 Lic. Luis Donaldo Colosio Murrieta. Instituto Mexicano del Seguro Social de Ciudad Obregón, Sonora

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    Objective: To present our experience and assess the recurrence of juvenile nasopharyngeal angiofibroma after a surgical treatment (open versus endoscopic approach) in the country’s northwestern Department of Otorhinolaryngology. Materials and methods: An observational, retrospective, analytical study. The medical records of patients diagnosed with juvenile nasopharyngeal angiofibroma, who were treated at the Department of Otorhinolaryngology – Head and Neck Surgery of this institution from 2014 to 2017, were reviewed. Results: A total of 19 patients diagnosed with juvenile nasopharyngeal angiofibroma underwent a surgical procedure, out of which 14 had an open surgery and 5 an endoscopic one. Recurrence accounted for 50 % and 40 %, respectively, which was not statistically significant (p = 0.88). However, other variables were compared, such as the need for admission to the Intensive Care Unit (ICU), which was represented by 71 % in the case of the open approach and 20 % for the endoscopic approach, where a significant difference was found (p = 0.04). Conclusions: The study shows no statistically significant advantage of the endoscopic approach versus the open approach, but demonstrates less need for ICU admissions, which would reduce healthcare costs
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