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Search Results: 1 - 10 of 462185 matches for " J. Fernández-Gómez "
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Shock Dynamics In Relativistic Jets
J. Cantó,S. Lizano,M. Fernández-López,R. F. González,A. Hernández-Gómez
Physics , 2013, DOI: 10.1093/mnras/stt072
Abstract: We present a formalism of the dynamics of internal shocks in relativistic jets where the source has a time-dependent injection velocity and mass-loss rate. The variation of the injection velocity produces a two-shock wave structure, the working surface, that moves along the jet. This new formalism takes into account the fact that momentum conservation is not valid for relativistic flows where the relativistic mass lost by radiation must be taken into account, in contrast to the classic regime. We find analytic solutions for the working surface velocity and radiated energy for the particular case of a step function variability of the injection parameters. We model two cases: a pulse of fast material and a pulse of slow material (with respect to the mean flow). Applying these models to gamma ray burst light curves, one can determine the ratio of the Lorentz factors gamma_2 / gamma_1 and the ratio of the mass-loss rates dot{m_2} / dot{m_1} of the upstream and downstream flows. As an example, we apply this model to the sources GRB 080413B and GRB 070318 and find the values of these ratios. Assuming a Lorentz factor gamma_1=100, we further estimate jet mass-loss rates between dot{m_1} ~ 10^{-5}-1 Msun.yr^{-1}. We also calculate the fraction of the injected mass lost by radiation. For GRB 070318 this fraction is ~7%. In contrast, for GRB 080413B this fraction is larger than 50%; in this case radiation losses clearly affect the dynamics of the internal shocks.
The Laughter of Ticklishness Is a Darwinian Feature Related to Empathy in Both Genders: Self-Esteem in Men and Sexism in Women  [PDF]
Verónica Juárez-Ramos, Elvira Salazar-López, María ángeles Rodríguez Artacho, K. Chmielowiec, A. Riquelme, J. Fernández-Gómez, A. I. Fernández-Ramirez, A. Vicente de Haro, A. Miranda, M. Caballero, B. Machado, Antonio González Hernández, Emilio Gómez Milán
Open Journal of Medical Psychology (OJMP) , 2014, DOI: 10.4236/ojmp.2014.31002
Abstract: The theory of false alarm for laughter could explain the involuntary laugh when someone is tickled. To put this hypothesis to the test, we handed out a questionnaire (180 items) with two hundred university students. Our main results are: In women who like being tickled, we discover components related to pleasure, erotism, feeling of affection, arousal, uncontrollability, domination, sexism and Darwinian (golden ratio) and psychological traits (empathy, low schizotypy and external locus of control) that are not present in the laughter at a stumble. The relation of both types of laughter with sense of humor is also differential. In men who like being tickled, we discover components related to masturbation, sexual fantasies, erotism, arousal, domination, sexist humour and Darwinian (square chin, feeling of masculinity) and psychological traits (empathic stress, low schizotypy, external locus of control and overall self-esteem). The relationship between being tickled and self-esteem shows a double aspect in men: It is positive in men who like being tickled and negative in men who do not like being tickled. For women there is not a relationship between self-esteem and tickling. Our conclusion is that laughter of ticklishness is a Darwinian feature related to empathy.

 

Matrix Metalloproteinases and Bladder Cancer: What is New?
O. Rodriguez Faba,J. Palou-Redorta,J. M. Fernández-Gómez,F. Algaba,N. Eiró,H. Villavicencio,F. J. Vizoso
ISRN Urology , 2012, DOI: 10.5402/2012/581539
Abstract: Urothelial bladder cancer represents a heterogeneous disease with divergent pathways of tumorigenesis. Tumor invasion and progression are a multifactorial process promoted by microenvironmental changes that include overexpression of matrix metalloproteinases (MMPs). Recent data clearly challenge the classic dogma that MMPs promote metastasis only by modulating the remodeling of extracellular matrix. Indeed, MMPs have also been attributed as an impact on tumor cell behavior in vivo as a consequence of their ability to cleave growth factors, cell surface receptors, cell adhesion molecules, and chemokines/cytokines. Levels of the different MMPs can be measured in several sample types, including tissue, blood (serum and plasma), and urine, and using different methodologies, such as immunohistochemistry, real-time PCR, western and northern blot analyses, enzyme-linked immunosorbent assay, and zymography. Several MMPs have been identified as having potential diagnostic or prognostic utility, whether alone or in combination with cytology. Although MMP inhibitors have shown limited efficacy, advances in the understanding of the complex physiologic and pathologic roles of MMPs might permit the development of new MMP-specific and tumor-specific therapies. In this paper we update the understanding of MMPs based on a systematic PubMed search encompassing papers published up to December 2011. 1. Introduction Urothelial bladder carcinoma (UBC) represents a heterogeneous disease with high morbidity and mortality. It ranks fifth among all cancers in the Western world, and there are 336,000 new cases and 132,000 deaths annually worldwide [1]. UBC mainly affects the elderly, with the peak incidence occurring after the age of 50. It is more common in males, in white people, and in developing countries. Most cases are sporadic, so a familial history is lacking. Cigarette smoking is a major risk factor. Other risk factors include exposure to arylamines, radiotherapy to adjacent organs, alkylating chemotherapeutic agents, and chronic inflammation [2]. There are two theories regarding the multifocal nature of urothelial carcinoma: “field cancerization” and “monoclonality” [3]. Genetic studies support the monoclonality theory and indicate that tumor cells spread from their origins to multiple sites by intraepithelial or intraluminal seeding. Non-muscle-invasive (NMI) disease accounts for ca. 70% of cases. Despite treatment with BCG, high-grade NMI tumors are associated with a high risk of recurrence and progression. Approximately 20% of primary diagnosed UBCs are muscle
Matrix Metalloproteinases and Bladder Cancer: What is New?
O. Rodriguez Faba,J. Palou-Redorta,J. M. Fernández-Gómez,F. Algaba
ISRN Urology , 2012, DOI: 10.5402/2012/581539
Abstract:
Modelo analítico que describe el comportamiento térmico de un sistema de descarga de calor en techos
Hernández-Gómez, VH.;Contreras-Espinosa, J.J.;González-Ortiz, G.;Morillón-Gálvez, D.;Fernández-Zayas, J.L.;
Ingeniería, investigación y tecnología , 2012,
Abstract: the present study proposes an analytical model which describes the thermal behavior of a heat discharge system in roof, when the surfaces that constitute it are not translucent. such a model derives from a thermal balance carried out to a heat discharge system in roofs. to validate it, an experimental prototype that allows simulating the thermal behavior of a heat discharge system in wall and roof was used, and the results were compared to those obtained with the proposed analytical model. it was found that the thermal behavior of the analytical model is similar to the thermal behavior of the experimental prototype; a worthless variation was detected among their respective outcome (the difference of temperatures can be caused by the heat transfer coefficient, of which no studies defining its behavior accurately have been found). therefore, it can be considered that the proposed analytical model can be employed to simulate the thermal behavior of a heat discharge system in roofs when the surfaces that constitute it are opaque.
A Jumping Cylinder on an Incline
R. W. Gómez,J. J. Hernández-Gómez,V. Marquina
Physics , 2012, DOI: 10.1088/0143-0807/33/5/1359
Abstract: The problem of a cylinder of mass m and radius r, with its center of mass out of the cylinder axis, rolling on an incline that makes an angle with respect to the horizontal is analyzed. The equation of motion is partially solved to obtain the site where the cylinder loses contact with the incline (jumps). Several simplifications are made: the analyzed system consists of an homogeneous disc with a one dimensional straight line of mass parallel to the disc axis at a distance y < r of the center of the cylinder. To compare our results with experimental data, we use a Styrofoam cylinder to which a long brass rod was imbibed parallel to the disc axis at a distance y < r from it, so the center of mass lies at a distance d from the center of the cylinder. Then the disc rolls without slipping on a long wooden ramp inclined at 15, 30 and 45 degrees with respect to the horizontal. To determine the jumping site, the motion was recorded with a high-speed video camera (Casio EX ZR100) at 200 and 480 frames per second. The experimental results agree well with the theoretical predictions.
Magnetoabsorption and magnetic hysteresis in Ni ferrite nanoparticles
Hernández-Gómez P.,Mu?oz J. M.,Valente M. A.,Torres C.
EPJ Web of Conferences , 2013, DOI: 10.1051/epjconf/20134017003
Abstract: Nickel ferrite nanoparticles were prepared by a modified sol-gel technique employing coconut oil, and then annealed at different temperatures in 400-1200 °C range. This route of preparation has revealed to be one efficient and cheap technique to obtain high quality nickel ferrite nanosized powder. Sample particles sizes obtained with XRD data and Scherrer’s formula lie in 13 nm to 138 nm, with increased size with annealing temperature. Hysteresis loops have been obtained at room temperature with an inductive method. Magnetic field induced microwave absorption in nanoscale ferrites is a recent an active area of research, in order to characterize and explore potential novel applications. In the present work microwave magnetoabsorption data of the annealed nickel ferrite nanoparticles are presented. These data have been obtained with a system based on a network analyzer that operates in the frequency range 0 - 8.5 GHz. At fields up to 400 mT we can observe a peak according to ferromagnetic resonance theory. Sample annealed at higher temperature exhibits different absorption, coercivity and saturation magnetization figures, revealing its multidomain character.
Patterns and architecture of genomic islands in marine bacteria
Fernández-Gómez Beatriz,Fernàndez-Guerra Antonio,Casamayor Emilio O,González José M
BMC Genomics , 2012, DOI: 10.1186/1471-2164-13-347
Abstract: Background Genomic Islands (GIs) have key roles since they modulate the structure and size of bacterial genomes displaying a diverse set of laterally transferred genes. Despite their importance, GIs in marine bacterial genomes have not been explored systematically to uncover possible trends and to analyze their putative ecological significance. Results We carried out a comprehensive analysis of GIs in 70 selected marine bacterial genomes detected with IslandViewer to explore the distribution, patterns and functional gene content in these genomic regions. We detected 438 GIs containing a total of 8152 genes. GI number per genome was strongly and positively correlated with the total GI size. In 50% of the genomes analyzed the GIs accounted for approximately 3% of the genome length, with a maximum of 12%. Interestingly, we found transposases particularly enriched within Alphaproteobacteria GIs, and site-specific recombinases in Gammaproteobacteria GIs. We described specific Homologous Recombination GIs (HR-GIs) in several genera of marine Bacteroidetes and in Shewanella strains among others. In these HR-GIs, we recurrently found conserved genes such as the β-subunit of DNA-directed RNA polymerase, regulatory sigma factors, the elongation factor Tu and ribosomal protein genes typically associated with the core genome. Conclusions Our results indicate that horizontal gene transfer mediated by phages, plasmids and other mobile genetic elements, and HR by site-specific recombinases play important roles in the mobility of clusters of genes between taxa and within closely related genomes, modulating the flexible pool of the genome. Our findings suggest that GIs may increase bacterial fitness under environmental changing conditions by acquiring novel foreign genes and/or modifying gene transcription and/or transduction.
Cruzamiento natural de chia (Salvia hispanica L.)
Hernández-Gómez, J. A.;Miranda-Colín, S.;Pe?a-Lomelí, A.;
Revista Chapingo. Serie horticultura , 2008,
Abstract: mexico has the largest genetic diversity of chia (salvia hispanica l.). recently, chia seed derivates have attracted commercial attention. however, too little is known about its breeding system to define a genetic improvement strategy and to preserve its germplasm. in this study, the percentage of natural outcrossing of s. hispanica was determined in chapingo, mexico. flower color was used as the genetic marker, considering purple flowers dominant over white and blue flowers. two cross-pollination plots were established in 1999. in the first plot, seeds of purple-flowered plants and white-flowered plants of a cultivated genotype from jalisco were sown alternately in each row; in the other, the same cultivar were sown alternately with seeds of purple-flowered cultivated plants and blue-flowered wild plants collected in sinaloa. determination of natural outcrossing rate was based on the percentage of purple-flowered plants in both the f1 progeny of white-flowered cultivated plants and of blue-flowered wild plants. outcrossing was more frequent in the cultivated genotype (22.17%) than in the wild genotype (1.51%), which might indicate that the breeding system was modified under cultivation. since there was no reproductive isolation, the cultivated and wild genotypes should be considered subspecies or races of s. hispanica. the resulting hybrids were vigorous, like the cultivated parent, and had dehiscent fruits, like the wild parent.
Analytical Model to Describe the Thermal Behavior of a Heat Discharge System in Roofs
Hernández-Gómez V.H.,Contreras-Espinosa J.J.,González-Ortiz G.,Morillón-Gálvez D.
Ingeniería, investigación y tecnología , 2012,
Abstract: The present study proposes an analytical model which describes the thermal behavior of a heat discharge system in roof, when the surfaces that constitute it are not translucent. Such a model derives from a thermal balance carried out to a heat discharge system in roofs. To validate it, an experimental prototype that allows simulating the thermal behavior of a heat discharge system in wall and roof was used, and the results were compared to those obtained with the proposed analytical model. It was found that the thermal behavior of the analytical model is similar to the thermal behavior of the experimental prototype; a worthless variation was detected among their respective outcome (The difference of temperatures can be caused by the heat transfer coefficient, of which no studies defining its behavior accurately have been found). Therefore, it can be considered that the proposed analytical model can be employed to simulate the thermal behavior of a heat discharge system in roofs when the surfaces that constitute it are opaque.
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