Advanced search


Knowledge area




32 results, page 1 of 4

Collision of propagating vortices embedded within Airy beams

Carmelo Rosales-Guzmán VALERIA RODRIGUEZ FAJARDO RUBEN RAMOS GARCIA (2013)

We present the engineered collision of two curvilinear propagating optical vortices each embedded in the main lobe of an Airy beam. Two cases are analyzed: same and opposite unitary topological vortex charge. We observed experimentally that in the first case the main vortices repel each other and remain separated after the collision. On the contrary, in the second case an annihilation of the main vortices occurs. Our experimental observations are reinforced by numerical simulations showing that the conservation of topological charge dictates the vortex dynamics.

Article

Collision of propagating Optical vortices Airy beam CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA FÍSICA ÓPTICA ÓPTICA

Estrategia teórico-didáctica para formar el concepto de gráfica y función lineal en el registro geométrico.

ANGIE DAMIAN MOJICA ARMANDO MORALES CARBALLO (2020)

A theoretical-didactic strategy is presented with a variational approach that favors the formation of the concept of linear function and that breaks with the classic presentation treated in the texts and other support resources that usually accompany the teaching and learning processes of the concept, in the pre-university level. The treatment begins in the geometric register to avoid the influence of notions related to the cartesian system and the representations.

Article

Didactic strategy Graph Trajectory covariational reasoning linear function HUMANIDADES Y CIENCIAS DE LA CONDUCTA PEDAGOGÍA

Selective photodeposition of zinc nanoparticles on the core of a single-mode optical fiber

RUBEN RAMOS GARCIA (2013)

An experimental and theoretical study about selective photodeposition of metallic zinc nanoparticles onto an optical fiber end is presented. It is well known that metallic nanoparticles possess a high absorption coefficient and therefore trapping and manipulation is more challenging than dielectric particles. Here, we demonstrate a novel trapping mechanism that involves laser-induced convection flow (due to heat transfer from the zinc particles) that partially compensates both absorption and scattering forces in the vicinity of the fiber end. The gradient force is too small and plays no role on the deposition process. The interplay of these forces produces selective deposition of particles whose size is directly controlled by the laser power. In addition, a novel trapping mechanism termed convective-optical trapping is demonstrated.

Article

Fiber optics, infrared Photothermal effects Optical tweezers or optical manipulation Laser trapping CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA FÍSICA ÓPTICA ÓPTICA

Consideraciones estratégicas para optimizar el diseño de la transferencia tecnológica dentro de las Instituciones de Educación Superior

MIGUEL ANGEL RUBIO TOLEDO Roxana Paola Benitez Abarca (2020)

Implica la creación de modelos de vinculación dirigidos a las IES, donde se justifique la necesidad de considerar departamento especializados que lleven a cabo las funciones de TT, así como determinar un marco jurídico que defina y regule dichas actividades. Se espera entonces, que la puesta en marcha de dicho manual, en primera instancia, logre una vinculación estrecha entre universidad e industria, así también se promueva y aumenten las redes para el desarrollo de las transferencias con los sectores productivos, con el objeto de lograr beneficios económicos y sociales para los involucrados en el proceso.

En la actualidad, el capital humano, el conocimiento y la tecnología son referentes importantes en el sector productivo. En los tres casos, son las Instituciones de Educación Superior quienes capacitan a sus estudiantes para desarrollar dichos conocimientos y tecnología una vez egresados o aún en las aulas. De tal suerte, resulta necesario que se observen los modos más adecuados para que los miembros de las Instituciones educativas se vinculen con la sociedad, ya sea en la iniciativa privada o sectores públicos. Diversos países han realizado con éxito dichas articulaciones estratégicas, no obstante, en México aún falta mucho para lograrlo. Si bien, existen estrategias institucionales que han dado excelentes resultados, tales como las incubadoras, los programas de prácticas profesionales, los incipientes departamentos de vinculación de las Instituciones Educativas, o incluso programas de las áreas científicas nacionales, los esfuerzos son incipientes. Así, el objetivo del presente trabajo es la conceptualización, discusión y consideración de diversos esfuerzos teóricos relacionados con la transferencia tecnológica, como acicate para lograr diseñar adecuadamente las estrategias en las Instituciones de Educación Superior que optimicen los esfuerzos en beneficio de las partes, es decir, la sociedad, la empresa e industria, el Estado y por supuesto la academia, con el objeto de responder a las necesidades de la población.

Article

Diseño de estrategias Educación Superior esquemas de vinculación transferencia tecnológica CIENCIAS SOCIALES

Coherent Quantum Transport in Photonic Lattices

Héctor Manuel Moya Cessa BLAS MANUEL RODRIGUEZ LARA (2013)

Transferring quantum states efficiently between distant nodes of an information processing circuit is of paramount importance for scalable quantum computing. We report on the first observation of a perfect state transfer protocol on a lattice, thereby demonstrating the general concept of transporting arbitrary quantum information with high fidelity. Coherent transfer over 19 sites is realized by utilizing judiciously designed optical structures consisting of evanescently coupled waveguide elements. We provide unequivocal evidence that such an approach is applicable in the quantum regime, for both bosons and fermions, as well as in the classical limit. Our results illustrate the potential of the perfect state transfer protocol as a promising route towards integrated quantum computing on a chip.

Article

Coherent quantum Transferring quantum CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA FÍSICA ÓPTICA ÓPTICA

OH Maser Sources in W49N: Probing Magnetic Field and Differential Anisotropic Scattering with Zeeman pairs using the VLBA

Eduardo Mendoza Torres (2013)

Our analysis of a VLBA 12-hour synthesis observation of the OH masers in awell-known star-forming region W49N has yielded valuable data that enables usto probe distributions of magnetic fields in both the maser columns and the inter-vening interstellar medium (ISM). The data consisting of detailed high angular-resolution images (with beam-width ∼20 milli-arc-seconds) of several dozen OH maser sources or spots, at 1612, 1665 and 1667 MHz, reveal anisotropic scatter broadening, with typical sizes of a few tens of milli-arc-seconds and axial ratios between 1.5 to 3. Such anisotropies have been reported earlier by Desai, Gwinn & Diamond (1994) and interpreted as induced by the local magnetic field parallel tothe Galactic plane. However, we find a) the apparent angular sizes on the averagea factor of about 2.5 less than those reported by Desai et al. (1994), indicating significantly less scattering than inferred earlier, and b) a significant deviation inthe average orientation of the scatter-broadened images (by ∼10 degrees) from that implied by the magnetic field in the Galactic plane. More intriguingly, for afew Zeeman pairs in our set, significant differences (up to 6σ) are apparent in thescatter broadened images for the two hands of circular polarization, even when apparent velocity separation is less than 0.1 km s⁻¹. This may possibly be the first example of a Faraday rotation contribution to the diffractive effects in the ISM. Using the Zeeman pairs, we also study the distribution of magnetic field inthe W49N complex, finding no significant trend in the spatial structure function.In this paper, we present the details of our observations and analysis leading tothese findings, discuss implications of our results for the intervening anisotropic magneto-ionic medium, and suggest the possible implications for the structure of magnetic fields within this star-forming region.

Article

Masers ISM: molecules Magnetic fields Individual (W49N) Radio lines: ISM Structure function CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA ASTRONOMÍA Y ASTROFÍSICA ASTRONOMÍA Y ASTROFÍSICA

Aplicación de la aminocatálisis en la síntesis estereoselectiva de compuestos cíclicos altamente funcionalizados a través del modo de activación trienamina

JESSICA ROSARIO GUTIERREZ CANO (2019)

En la presente disertación se describe la aplicación de la organocatálisis asimétrica en reacciones de cicloadición [4+2] a través del modo de activación trienamina. Dicho intermediario trienamina, se generó a través de la condensación de un aminocatalizador quiral con 2,4-dienales, adquiriendo el carácter de un dieno, el cual mediante una reacción del tipo Diels-Alder con diferentes dienófilos, dio como resultado la síntesis de cicloaductos con cierto grado de estereocontrol. Por lo anterior, en el presente proyecto se expone una metodología de síntesis para la obtención de una pequeña familia de derivados tetrahidrocarbazólicos y de tipo ciclohexeno funcionalizados a través de la estrategia de aminocatálisis asimétrica. El empleo de aminas secundarias quirales como catalizadores permitió observar una ostensible estereoselectividad en la reacción. Sin embargo, la reactividad de los 2,4-dienales evaluados nos permitió identificar algunas limitaciones en nuestra metodología. Del mismo modo, se investigó la posibilidad de funcionalizar los productos de cicloadición enantioméricamente enriquecidos, a través de una serie de transformaciones químicas con la finalidad de obtener estructuras moleculares de interés sintético, abriendo paso a su posible aplicación como bloques de construcción.

In the present dissertation,the application of organocatalytic [4 + 2] cycloaddition reactions through trienamine activation mode is described. The trienamine intermediate was generated by condensation of achiral aminocatalyst with 2,4-dienals, acquiring the character of a diene, which by Diels-Alder reaction with different dienophiles, gave the synthesis of cycloadducts with a certain degree of stereo control. Therefore, in this project we present asynthetic methodology for obtaining a small family of functionalized tetrahydrocarbazole and cyclohexene derivatives through the asymmetric aminocatalysis strategy. The use of chiral secondary amines as catalysts allowed to observe an evident stereoselectivity in there action. However, the reactivity of the 2,4-dienals evaluated allowed us to identify some limitations of our methodology. In the same way, we also investigated functionalization possibilities of our enantioenriched cycloaddition products through aseveral chemical transformations in order to furnish molecular structures with synthetic interest, opening the way to their possible application as building blocks.

Master thesis

BIOLOGÍA Y QUÍMICA QUÍMICA QUÍMICA ORGÁNICA Aminocatálisis asimétrica Compuestos cíclicos - Síntesis estereoselectiva Tetrahidrocarbazólicos - Derivados Ciclohexeno - Derivados Hidrocarburos – Funcionalización Asymmetric aminocatalysis Cyclic Compounds - Stereoselective Synthesis Tetrahydrocarbazoles - Derivatives Cyclohexene - Derivatives Hydrocarbons - Functionalization

THE CHROMOSPHERIC SOLAR MILLIMETER-WAVE CAVITY ORIGINATES IN THE TEMPERATURE MINIMUM REGION

Victor De la Luz (2013)

We present a detailed theoretical analysis of the local radio emission at the lower part of the solar atmosphere. To accomplish this, we have used a numerical code to simulate the emission and transport of high-frequency electromagnetic waves from 2 GHz up to 10 THz. As initial conditions, we used VALC, SEL05, and C7 solar chromospheric models. In this way, the generated synthetic spectra allow us to study the local emission and absorption processes with high resolution in both altitude and frequency. Associated with the temperature minimum predicted by these models, we found that the local optical depth at millimeter wavelengths remains constant, producing an optically thin layer that is surrounded by two layers of high local emission. We callthis structure the Chromospheric Solar Millimeter-wave Cavity (CSMC). The temperature profile, which features temperature minimum layers and a subsequent temperature rise, produces the CSMC phenomenon. The CSMCshows the complexity of the relation between the theoretical temperature profile and the observed brightness temperature and may help us to understand the dispersion of the observed brightness temperature in the millimeter wavelength range.

Article

Methods: numerical Radiation mechanisms: thermal Radiative transfer Stars: chromospheres Sun: chromosphere Sun: radio radiation CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA ASTRONOMÍA Y ASTROFÍSICA ASTRONOMÍA Y ASTROFÍSICA

Estimation of radiated energy using the EGF technique: what should be the upper limit of integration in the frequency domain?

Shri Krishna Singh (2007)

The empirical Green's function (EGF) technique is frequently used to estimate the radiated seismic energy, ER, of an earthquake. An approximation of the moment-rate spectrum, M0(f), of the target earthquake is obtained from the ratio of the spectrum of the target earthquake to the spectrum of the EGF earthquake, and the radiated seismic energy is computed by integrating f2M0 2(f) over frequency f. The choice of the upper limit of integration, fu, is critical. In this note we show that the optimum choice of fu, for the ω2-source model is given by fu/fc1∼ fc2/fc1, where fc1 and fc2 are the corner frequencies of the target and the EGF earthquakes, respectively. This result provides a useful guide in the application of the EGF technique to obtain a reliable estimate of the radiated seismic energy.

Article

TERREMOTOS ANÁLISIS EMPÍRICO MÉTODO DE ESTIMACIÓN FUNCIÓN VERDE ANÁLISIS DE FIABILIDAD SISMICIDAD Earthquake Empirical analysis Estimation method Green function Reliability analysis Seismicity CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO GEOFÍSICA SISMOLOGÍA Y PROSPECCIÓN SÍSMICA concept8601 Seismology

Influencia del programa Oportunidades en el comercio de La Concordia, Ayutla de los Libres, Guerrero.

NEFTALI GARCIA CASTRO ALVARO SANCHEZ CRISPIN (2016)

This paper examines the territorial effects of a Program geared to alleviating poverty, called Oportunidades. This is done by looking at the consequences of cash transfers of this pro gram in an ethnic settlement, La Concordia,

in the State of Guerrero, Mexico. A semi-struc tured questionnaire was the research instru ment useful to interrogate key actors of the local commercial sector about demand-offer trends in La Concordia. We firstly describe the so cio-economic characteristics of Ayutla, its role in the dynamic of the regional economy and the type of commercial activity present in county seat and smaller villages, most of which have a predominant indian population.

Article

commercial activity cash-transfers Oportunidades Ayutla Guerrero Mexico CIENCIAS SOCIALES SOCIOLOGÍA OTRAS ESPECIALIDADES SOCIOLÓGICAS