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Color pattern and body size variation in live Aspidoscelis costatus costatus (Squamata: Teiidae) from a protected enclave in southern Mexico

ALDO GOMEZ BENITEZ Oswaldo Hernández Gallegos Brittany Lovell Pelagie Kadia JAMES MARTIN WALKER (2020)

Coloración en la lagartija Aspidoscelis costatus costatus

Whiptail lizards in the sexlineatus species group (genus Aspidoscelis) in North America represent some of the most challenging patterns of variation in the North American herpetofauna. The range of color patterns in these populations is based on individual, ontogenetic, sexual, seasonal, and/or geographic variation. We studied representatives of a population of Western Mexico Whiptail (A. costatus costatus) from a protected private enclave of approximately 0.27 ha in the municipality and city of Ixtapan de la Sal, Estado de México, México. We captured 50 lizards in 2016 and 24 in 2018, most of which we photographed ex situ and a few in situ. These photographs revealed that a variety of age/size related dorsal and ventral patterns were consistently present. Males progressed through five stages of dorsal pattern changes from pale stripes, dark intervening fields, no spots to spots, and diverse pale configurations set in a black ground color. Females in this population showed similar changes but did not lose striping as they grew. Ontogenetic changes in ventral color patterns were also apparent, with males becoming more colorful than females. The adaptive significance of extensive color pattern variation in this urban population of A. c. costatus warrants further study.


adaptive significance Balsas Basin Whiptail body size dorsal coloration Mexican lizards ontogeny spots stripes ventral coloration BIOLOGÍA Y QUÍMICA

A classical simulation of nonlinear Jaynes–Cummings and Rabi models in photonic lattices


The interaction of a two-level atom with a single-mode quantized field is one of the simplest models in quantum optics. Under the rotating wave approximation, it is known as the Jaynes-Cummings model and without it as the Rabi model. Real-world realizations of the Jaynes-Cummings model include cavity, ion trap and circuit quantum electrodynamics. The Rabi model can be realized in circuit quantum electrodynamics. As soon as nonlinear couplings are introduced, feasible experimental realizations in quantum systems are drastically reduced. We propose a set of two photonic lattices that classically simulates the interaction of a single two-level system with a quantized field under field nonlinearities and nonlinear couplings as long as the quantum optics model conserves parity. We describe how to reconstruct the mean value of quantum optics measurements, such as photon number and atomic energy excitation, from the intensity and from the field, such as von Neumann entropy and fidelity, at the output of the photonic lattices. We discuss how typical initial states involving coherent or displaced Fock fields can be engineered from recently discussed Glauber-Fock lattices. As an example, the Buck-Sukumar model, where the coupling depends on the intensity of the field, is classically simulated for separable and entangled initial states.


Propagation Coupled Resonators Photonic Crystals Quantum Optics Quantum Electrodynamics Guided Wave Applications CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA FÍSICA ÓPTICA ÓPTICA

Transmission function of collinear acousto-optical interaction occurred by acoustic waves of finite amplitude

ALEXANDER SHCHERBAKOV Adán Omar Arellanes Bernabe (2013)

New physical aspects of collinear acousto-optical interaction, occurred by acoustic waves of finite amplitude, are revealed and analyzed in crystalline materials exhibiting moderate linear acoustic losses. The analysis is performed in the regime of continuous traveling waves allowing a specific mechanism of the acousto-optic nonlinearity. Our consideration has shown that such nonlinearity together with linear acoustic losses is able to affect the transmission function inherent in collinear interaction. In particular, the mere presence of linear acoustic losses by themselves leads to broadening the width of the transmission function beginning already from very low levels of the applied acoustic power. Moreover, the transmission function exhibits a marked and quasi-periodical dependence on the applied acoustic power density, and that periodicity is governed by the linear acoustic losses. As a result, the transmission function can be significantly narrowed near isolated points at the cost of decreasing the interaction efficiency. These novelties related to collinear acousto-optical interaction accompanied by moderate linear acoustic losses have been studied and confirmed experimentally with an advanced acousto-optical cell based on calcium molybdate (CaMoO4) single crystal and controlled by acoustic waves of finite amplitude. © 2013 Optical Society of America


Dynamic gratings Nonlinear optics Parametric processes Acousto-optical devices CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA FÍSICA ÓPTICA ÓPTICA

Amorphous silicon-liquid crystals device forphotonic applications


We demonstrate that an hydrogenated amorphous silicon (a:SiH)-liquid crystals hybrid device could be used for the recording of high resolution (0.8-2 µm) dynamic holograms. A maximum diffraction efficiency of 3.3% was obtained at low power (1.5 mW) He-Ne laser. The nonlinear refractive index change at 0.6 W/cm2 is n2~1x10−2 cm2 /W, although small compared to that obtained in dye-doped liquid crystal, is equal to the reported in pure liquid crystal although with much higher power density (~50 W/cm2 ). The device operates in the red to near-infrared part of the spectrum which makes it attractive due to its potential applications in telecommunications and military applications.


Nonlinear optics Diffraction gratings Holography Liquid crystals CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA FÍSICA ÓPTICA ÓPTICA

Fiber Optic Sensor for High-Sensitivity Salinity Measurement

José Javier Sánchez Mondragón (2013)

A highly sensitive salinity sensor based on a two-core optical fiber is demonstrated for both high- and low-concentration regimes. Salinity of several aqueous solutions is measured in the ranges from 0 to 5 mol/L and from 0 to 1 mol/L with sensitivities of 14.0086 and 12.0484 nm/(mol/L), respectively. The achieved sensitivity is ∼19 times higher than that recently reported for polymide-coated photonic crystal fibers.


Fiber optics sensor In-fiber directional coupler Salinity sensor CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA FÍSICA ÓPTICA ÓPTICA

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


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.


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

Effect of size and composition on the second harmonic generation from lithium niobate powders at different excitation wavelengths



LiNbO3 microcrystalline systems, possessing almost stoichiometric composition, were produced by varying the temperature and time parameters in the annealing processes following a mechanochemical reaction of raw powders. SHG from these samples, detected for every fundamental wavelength in the range 800-1300 nm, and being maximal at a certain wavelength, λmax, for each sample, has been addressed to a random scattering of the induced nonlinear polarizations. Possible tuning of λmax could be ascribed to control of composition and grain size of the sample. Random orientation of the produced nanocrystallites was verified since no dependence for SHG intensity on incident polarization was observed.

PAPIIT-UNAM through grant IN117116 Y “RED PRODEP-SEP Compuestos poliméricos propiedades y aplicaciones 2015-2016”


Second Harmonic Generation Nonlinear Optics Materials Nanomaterials Lithium Niobate BIOLOGÍA Y QUÍMICA

A photonic crystal realization of a phase driven two-level atom


We propose a set of photonic crystals that realize a nonlinear quantum Rabi model equivalent to a two-level system driven by the phase of a quantized electromagnetic field. The crystals are exactly solvable in the weak-coupling regime; their dispersion relation is discrete and the system is diagonalized by normal modes similar to a dressed state basis. In the strong-coupling regime, we use perturbation theory and find that the dispersion relation is continuous. We give the normal modes of the crystal in terms of continued fractions that are valid for any given parameter set. We show that these photonic crystals allow state reconstruction in the form of coherent oscillations in the weak-coupling regime. In the strong-coupling regime, the general case allows at most partial reconstruction of single waveguide input states, and non-symmetric coherent oscillations that show partial state reconstruction of particular phase-controlled states.


Photonic crystals Classical and quantum physics Classical simulation of quantum optics CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA FÍSICA ÓPTICA ÓPTICA

Reconocimiento de patrones invariante a desplazamiento, escala y rotación vía transformada radial de Hilbert optimizada

Displacement, scale and rotation invariant pattern recognition by Radial Hilbert Transform Optimized

José Alfredo Castro Valdez (2021)

La identificación y clasificación de imágenes tiene múltiples aplicaciones, así como metodologías para llevarse a cabo. En este trabajo se utilizó una metodología con invariancia a desplazamiento, escala y rotación, estas invariancias se logran al utilizar un conjunto de transformadas. La transformada de Fourier tiene la propiedad de invarianza a desplazamiento mientras que la transformada de Mellin genera la invarianza a escala, por otra parte, la transformada radial de Hilbert transforma una imagen en una firma vectorial, la cual tiene invarianza a rotación. Esta nueva metodología toma una imagen centrada y le aplica la trasformada Fourier-Mellin. Se utilizan las máscaras de anillos concéntricos obtenidos a partir de la transformada Radial de Hilbert y se hace una multiplicación punto a punto con el módulo de la transformada FourierMellin. Los valores en cada anillo se suman y con ellos se forma una firma vectorial cuya longitud está relacionada con el número de anillos concéntricos y además es invariante a escala, rotación y desplazamiento. En este trabajo se partió de la metodología previamente mencionada y se propuso una adaptación de la transformada radial de Hilbert en el cual la cantidad de anillos concéntricos obtenida fuera máxima, a esta versión se le llamó transformada radial de Hilbert optimizada (RHTO). Para comparar entre firmas vectoriales se utilizó el filtro clásico y se desarrolló un nuevo filtro de correlación que se adapta entre los casos lineal y no lineal dependiendo de firmas a correlacionar, a este filtro se le llamó filtro lineal / no-lineal adaptativo. Para evaluar la metodología propuesta se utilizaron imágenes de 30 especies de fitoplancton con diferentes escalas y rotaciones. Además, a cada combinación de escala y rotación se les aplicó un conjunto patrones de iluminación no homogéneo obteniendo. Los valores de correlación obtenidos fueron analizados con una matriz de confusión donde se compararon diferentes parámetros estadísticos, encontrando que al utilizar la metodología RHTO y el filtro adaptativo se obtienen mejores valores de clasificación exitosa.

Image classification has multiple applications and methodologies to be carried out. In this work, a method with invariance to displacement, scale, and rotation was used. These invariances are achieved by using a set of transforms. The Fourier transform has the property of displacement invariance, while the Mellin transform generates scale invariance. On the other hand, the radial Hilbert transform transforms an image into a vector signature, which has rotation invariance. This new methodology takes a centered image and applies the Fourier-Mellin transform to it. The concentric ring masks obtained from the Radial Hilbert transform are used, and a point-to-point multiplication is made with the module of the Fourier-Mellin transform. The values in each ring are added, and with them, a vector signature is formed whose length is related to the number of concentric rings and is also invariant to displacement, scale, and rotation. In this work, we started from the previously mentioned methodology, and an adaptation of the radial Hilbert transform was proposed in which the number of concentric rings obtained was maximum. This version was called optimized radial Hilbert transform (RHTO). When correlating images in one or two dimensions, you must decide the correlation filter to use. The new methodology used the classical filter. A new filter was developed that adapts between linear and nonlinear cases depending on the signatures correlated; this filter was called the adaptive linear/nonlinear filter. Thirty phytoplankton species with different scales and rotations were used to evaluate the proposed methodology. In addition, a set of non-homogeneous lighting patterns was applied to each combination of scale and rotation. A confusion matrix analyzed the correlation values obtained where different statistical parameters were compared, finding that better values for successful classification were obtained when using the RHTO methodology and the adaptive filter.

Doctoral thesis

Transformada radial de Hilbert optimizada, correlación adaptativa, Firmas unidimensionales, Transformada de Fourier, Reconocimiento de patrones, Clasificación de imágenes Radial Hilbert transform optimized, Adaptive correlation, Unidimensional signatures, Fourier transform, Pattern recognition, Image classification CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA FÍSICA ÓPTICA OPTICA FÍSICA OPTICA FÍSICA