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A method adding phase-shifting capacity in two mutually perpendicular axes to the Ronchi test is presented in this work. The phase of the object with the position of the reflected ray on the grating was identified and used to solve the equation of reflection in two orthogonal directions. In this manner, the test-surface figure was obtained. The procedure was demonstrated with an inverse qualitative test and a direct, quantitative test. Both tests give results comparable to Fizeau interferometry, with the precision of the order of 25 nm peak to valley. This technique is a good alternative to interferometry because, in addition to its inherent high-resolution, it is possible to obtain the radius of curvature and conic constant, which interferometers, requiring auxiliary optics, cannot provide. This method also has a high dynamic range and is not as susceptible to vibrations or turbulence. The setup can be built with low-cost, readily available components, is easily aligned, uses a white light source, and can be made very lightweight and compact, which makes it ideal for mounting onto existing polishing machines in any optical fabrication workshop, to perform in situ surface metrology.

New hydrodynamic improvements have been developed in order to enable pulsed polishing with the HyDRa system. The operational parameters of the tool are not affected by these modifications, i.e., tool bias and the tool’s floating capability are not lost, and a linear erosion function is produced. The minimum removal is no longer ruled by maximum computer numerical control speed, allowing for high-precision removal that can be taken from zero to the maximum attainable of the tool, in minimum increments of 3.5 nm / ms. This modification also improves the convergence rate of the polishing process toward the desired surface. This development guarantees a high-speed, pulsed operation that enables the tool to be used in a variety of polishing modes, ranging from discrete pixel to continuous pulse width modulation (PWM) polishing. This new capability opens a wide range of applications that can now be tackled with the system, such as zonal and tessellated polishing. PWM capability also allows for simultaneous, multi-head polishing of large optical surfaces.

Summary: Neurodegenerative diseases are characterized by the formation and propagation of protein aggregates, especially amyloid fibrils. However, what normally suppresses protein misfolding and aggregation in metazoan cells remains incompletely understood. Here, we show that TRIM11, a member of the metazoan tripartite motif (TRIM) family, both prevents the formation of protein aggregates and dissolves pre-existing protein deposits, including amyloid fibrils. These molecular chaperone and disaggregase activities are ATP independent. They enhance folding and solubility of normal proteins and cooperate with TRIM11 SUMO ligase activity to degrade aberrant proteins. TRIM11 abrogates α-synuclein fibrillization and restores viability in cell models of Parkinson’s disease (PD). Intracranial adeno-associated viral delivery of TRIM11 mitigates α-synuclein-mediated pathology, neurodegeneration, and motor impairments in a PD mouse model. Other TRIMs can also function as ATP-independent molecular chaperones and disaggregases. Thus, we define TRIMs as a potent and multifunctional protein quality-control system in metazoa, which might be applied to treat neurodegenerative diseases.

En la práctica docente existen estrategias integradoras de alternativas, basadas en métodos que fomentan la atención de los estudiantes, apoyadas en las TIC, para mejorar el proceso de enseñanza-aprendizaje. La robótica educativa representa una opción motivadora que aventaja a los procesos pedagógicos tradicionales; hace que las asignaturas sean más atractivas y fáciles de trabajar. La sugerencia de un modelo pedagógico, que, en sus secciones de clases de matemática, tome en cuenta la robótica educativa, provee acciones que concentran y ayudan a la atención de los alumnos en las diversas actividades. En el presente artículo se propone un modelo pedagógico basado en la robótica educativa que mejora la motivación, atención y concentración de los estudiantes en el aprendizaje de la matemática de 6to grado de primaria. Toma en cuenta la investigación del estado del arte de los modelos pedagógicos con robótica educativa, sus características de uso actual en diversos países del mundo y República Dominicana. Este modelo propuesto es validado con un estudio de caso y con el método Iadov para conocer la satisfacción de los involucrados. De esta forma se comprueba que ayuda de manera significativa al proceso de enseñanza-aprendizaje de la matemática y que se logra una alta satisfacción con la aplicación del modelo pedagógico con la robótica educativa como apoyo didáctico en la enseñanza de matemática de 6to grado de primaria.

El experimento buscó medir y comparar el grado de precisión que los participantes ponen en práctica para identificar trayectorias de fuentes de emisión sonora envolventes experimentadas de un modo acusmático y audiovisualizado. El trabajo se inscribe en el campo de estudios sobre la transmodalidad. En particular respecto de aquellas investigaciones que se han enfocado en las correspondencias entre la escucha y la visualización. En este contexto desarrollamos una plataforma de reproducción en música acusmática (Luna, 2015; 2016) con el fin de propiciar una modalidad alternativa de presentación en concierto para este tipo de obras (Prager, 2012; Truax, 1999; Tutschku, 2001). La propuesta combina los campos de difusión envolvente de sonido (surround), como así también de emisiones de luces (lightrround), en sincronía con la propagación de modos vibratorios (sensurround) dirigidos también a la audiencia., The experiment sought to measure and compare the degree of precision that participants put into practice to identify trajectories of sorround sound emission sources experienced in an acousmatic and audiovisual way. The work is part of the field of studies on transmodality. In particular regarding those investigations that have focused on the correspondences between listening and visualization. In this context, we developed a platform for acousmatic music reproduction (Luna, 2015, 2016) in order to promote an alternative mode of presentation in concert for this type of works (Prager, 2012, Truax, 1999, Tutschku, 2001). The proposal combines the fields of surround sound diffusion, as well as lightrround, in synchrony with the propagation of vibratory modes (sensurround) also aimed at the audience., Sociedad Argentina para las Ciencias Cognitivas de la Música

Accumulation of aggregated α-synuclein into Lewy bodies is thought to contribute to the onset and progression of dopaminergic neuron degeneration in Parkinson's disease (PD) and related disorders. Although protein aggregation is associated with perturbation of proteostasis, how α-synuclein aggregation affects the brain proteome and signaling remains uncertain. In a mouse model of α-synuclein aggregation, 6% of 6215 proteins and 1.6% of 8183 phosphopeptides changed in abundance, indicating conservation of proteostasis and phosphorylation signaling. The proteomic analysis confirmed changes in abundance of proteins that regulate dopamine synthesis and transport, synaptic activity and integrity, and unearthed changes in mRNA binding, processing and protein translation. Phosphorylation signaling changes centered on axonal and synaptic cytoskeletal organization and structural integrity. Proteostatic responses included a significant increase in the levels of Lmp7, a component of the immunoproteasome. Increased Lmp7 levels and activity were also quantified in postmortem human brains with PD and dementia with Lewy bodies. Functionally, the immunoproteasome degrades α-synuclein aggregates and generates potentially antigenic peptides. Expression and activity of the immunoproteasome may represent testable targets to induce adaptive responses that maintain proteome integrity and modulate immune responses in protein aggregation disorders., Highlights • Relative quantification of 6215 proteins and 8183 phosphopeptides in a mouse model of endogenous aggregation of α-synuclein • The immunoproteasome component Lmp7, is increased in the mouse model and postmortem human brains with Parkinson's and DLB • Lmp7 may represent an adaptive response to protein aggregation through aggregate elimination and innate immunity activation Aggregated a-synuclein is a component of Lewy bodies a hallmark of Parkinson's disease. Changes in the brain proteome and phosphorylated peptides were quantified upon aggregation of α-synuclein in a mouse model. The levels and activity of LMP7, a component of the immunoproteasome, which is linked to proteostasis were increased indicating a potential adaptive response to α-synuclein aggregation.

Parkinson’s disease (PD) is a prevalent neurodegenerative disease with no approved disease-modifying therapies. Multiplications, mutations, and single nucleotide polymorphisms in the SNCA gene, encoding alpha-synuclein protein (aSyn), either cause or increase risk for PD. Intracellular accumulations of aSyn are pathological hallmarks of PD. Taken together, reduction of aSyn production may provide a disease-modifying therapy for PD. We show that antisense oligonucleotides (ASOs) reduce production of aSyn in rodent pre-formed fibril (PFF) models of PD. Reduced aSyn production leads to prevention and removal of established aSyn pathology and prevents dopaminergic cell dysfunction. In addition, we address the translational potential of the approach through characterization of human SNCA targeting ASOs that efficiently suppress the human SNCA transcript in vivo. We demonstrate broad activity and distribution of the human SNCA ASOs throughout the non-human primate brain and a corresponding decrease in aSyn cerebral spinal fluid (CSF) levels. Taken together, these data suggest that by inhibiting production of aSyn it may be possible to reverse established pathology and thus supports the development of SNCA ASOs as a potentially disease modifying therapy for PD and related synucleinopathies.SummaryAntisense oligonucleotides designed against SNCA, which are progressing to the clinic, have the potential to be a disease modifying therapeutic for Parkinson’s disease patients.

Alpha-synuclein is a presynaptic protein that forms abnormal cytoplasmic aggregates in Lewy body disorders. Although nuclear alpha-synuclein localization has been described, its function in the nucleus is not well understood. We demonstrate that alpha-synuclein modulates DNA repair. First, alpha-synuclein colocalizes with DNA damage response components within discrete foci in human cells and mouse brain. Removal of alpha-synuclein in human cells leads to increased DNA double-strand break (DSB) levels after bleomycin treatment and a reduced ability to repair these DSBs. Similarly, alpha-synuclein knock-out mice show increased neuronal DSBs that can be rescued by transgenic reintroduction of human alpha-synuclein. Alpha-synuclein binds double-stranded DNA and helps to facilitate the non-homologous end-joining reaction. Using a new, in vivo imaging approach that we developed, we find that serine-129-phosphorylated alpha-synuclein is rapidly recruited to DNA damage sites in living mouse cortex. We find that Lewy inclusion-containing neurons in both mouse model and human-derived patient tissue demonstrate increased DSB levels. Based on these data, we propose a model whereby cytoplasmic aggregation of alpha-synuclein reduces its nuclear levels, increases DSBs, and may contribute to programmed cell death via nuclear loss-of-function. This model could inform development of new treatments for Lewy body disorders by targeting alpha-synuclein-mediated DNA repair mechanisms.

La tesis indaga sobre una propuesta que explora otra modalidad de realización de conciertos en música acusmática para sonido multicanal envolvente, o bien en el marco de experiencias trisensoriales en contextos multimedia. Llamamos a esta propuesta Plataforma Inmersiva de Producciones Acusmáticas. En ella interviene la visualización de la espacialidad sonora envolvente, en conjunto con propagaciones físico/vibratorias. De este modo se buscó combinar los campos de la difusión, tanto de sonido envolvente (surround), como de proyección de luces (lightrround) dirigidas al público y sincronizadas con el sonido. A lo antedicho se le añade la emisión de modos físico/vibratorios (sensurround) propagados también a la audiencia. Mediante la sincronía entre las luces y el audio se persigue remarcar y dar énfasis visual a dos variables acústicas: a las trayectorias espaciales del sonido distribuidas entre los altavoces, y a las variaciones de su dinámica. Ambas variables se ven reflejadas por los emisores de luz conectados a cada altavoz. Mediante los modos físico/vibratorios procuramos balizar también las trayectorias espaciales del sonido, aunque de un modo táctil, incrementando la sincronía temporal e incluso espacial a tres modalidades sensoriales dirigidas al público. Mediante estas redundancias cognitivas (sincronía sonora/visual/táctil) pretendemos inducir en la audiencia una focalización atencional sobre la espacialización de sonido envolvente. Para dar cuenta de la integración de las diferentes áreas que confluyen en el proyecto, nos valdremos de un concepto que proviene del campo de la psicología de la percepción, la Transmodalidad. Es mediante estos campos que esta tesis se propone explorar y combinar, impulsando un cruce interdisciplinario donde las artes sonoras, los estudios de la percepción, y la tecnología se vinculan., Facultad de Bellas Artes

The accumulation of misfolded α-synuclein (aSyn) and neuron loss define several neurodegenerative disorders including Parkinson's disease (PD) and dementia with Lewy bodies (DLB). However, the precise relationship between pathology and neurotoxicity and why these processes disproportionately affect certain neuron subpopulations are poorly understood. We show here that Math2-expressing neurons in the hippocampal Cornu ammonis (CA), a region significantly affected by aSyn pathology in advanced PD and DLB, are highly susceptible to pathological seeding with pre-formed fibrils (PFFs), in contrast to dentate gyrus neurons, which are relatively spared. Math2+ neurons also exhibited more rapid and severe cell loss in both in vitro and in vivo models of synucleinopathy. Toxicity resulting from PFF exposure was dependent on endogenous aSyn and could be attenuated by N-acetyl-cysteine through a glutathione-dependent process. Moreover, aSyn expression levels strongly correlate with relative vulnerability among hippocampal neuron subtypes of which Math2+ neurons contained the highest amount. Consistent with this, antisense oligonucleotide (ASO)-mediated knockdown of aSyn reduced the neuronal pathology in a time-dependent manner. However, significant neuroprotection was observed only with early ASO intervention and a substantial reduction of aSyn pathology, indicating toxicity occurs after a critical threshold of pathological burden is exceeded in vulnerable neurons. Together, our findings reveal considerable heterogeneity in endogenous aSyn levels among hippocampal neurons and suggest that this may contribute to the selective vulnerability observed in the context of synucleinopathies.

In vertebrate neurons, the axon initial segment (AIS) is specialized for action potential initiation. It is organized by a giant 480 Kd variant of ankyrin G (AnkG) that serves as an anchor for ion channels and is required for a plasma membrane diffusion barrier that excludes somatodendritic proteins from the axon. An unusually long exon required to encode this 480Kd variant is thought to have been inserted only recently during vertebrate evolution, so the giant ankyrin-based AIS scaffold has been viewed as a vertebrate adaptation for fast, precise signaling. We re-examined AIS evolution through phylogenomic analysis of ankyrins and by testing the role of ankyrins in proximal axon organization in a model multipolar Drosophila neuron (ddaE). We find giant isoforms of ankyrin in all major bilaterian phyla, and present evidence in favor of a single common origin for giant ankyrins and the corresponding long exon in a bilaterian ancestor. This finding raises the question of whether giant ankyrin isoforms play a conserved role in AIS organization throughout the Bilateria. We examined this possibility by looking for conserved ankyrin-dependent AIS features in Drosophila ddaE neurons via live imaging. We found that ddaE neurons have an axonal diffusion barrier proximal to the cell body that requires a giant isoform of the neuronal ankyrin Ank2. Furthermore, the potassium channel shal concentrates in the proximal axon in an Ank2-dependent manner. Our results indicate that the giant ankyrin-based cytoskeleton of the AIS may have evolved prior to the radiation of extant bilaterian lineages, much earlier than previously thought., Author Summary The axon initial segment (AIS) is currently thought to be a distinguishing feature of vertebrate neurons that adapts them for rapid, precise signaling. It serves as a hub for the regulation of neuronal excitability as the site of action potential initiation and also acts as the boundary between the highly-specialized axon and the rest of the cell. Here we show that the giant ankyrins that structurally organize the AIS, and were thought to be vertebrate-specific, instead have an ancient origin in a bilaterian ancestor. We further show the presence of a giant ankyrin-dependent AIS-like plasma membrane boundary between the axon and soma in a Drosophila sensory neuron. These results suggest that the cytoskeletal backbone for the AIS is not unique to vertebrates, but instead may be an evolutionarily conserved feature of bilaterian neurons.

In this work we present a simulation of the wave-front sensing of the active primary mirror support for the 2.1-m telescope of the San Pedro Martir's Observatory by Non-Linear Curvature Wave-front Sensing. The active cell is going to be tested by changing its actuator values. In each active cell state, defocused pupil images from both sides of the focal plane will be simulated and phase retrieval will be performed. The algorithm employed to reconstruct the wave-front will be discussed, as well as the sensitivity obtained in our simulation.

El presente artículo comprende el diseño estructural de un secador con sistema de volteo para cafés especiales en el departamento del Huila el cual incluye: (i) Análisis de diseño para determinar la forma de la “uña de volteo” con la correspondiente herramienta definida, (ii) deducción de una ecuación aproximada para el cálculo del torque requerido para el volteo del café en pasera y (iii) un análisis CFD (computational fluid dynamics) del secador desde el punto de vista térmico para validar las variables de diseño. Se logró proponer un sistema híbrido con un factor de innovación que garantiza un café secado con condiciones controladas y en un menor tiempo, que introduce al agricultor en una dinámica de precisión en su objetivo de mantener los porcentajes permitidos de humedad, garantizando un café de calidad en taza.

En el artículo se presenta una propuesta para la realización de conciertos de música acusmática en donde interviene la visualización de la espacialidad y la dinámica sonora en conjunto con propagaciones físico/vibratorias dirigidas también a la audiencia. A través de los canales visuales y táctiles se busca enfatizar por un lado tanto a las trayectorias del sonido envolvente, como también a las variaciones dinámicas que se hubieran planteado en la composición, o bien a la producida durante la re-espacialización de la obra en vivo dirigida por un performer. A continuación, se describen las motivaciones del proyecto, su marco teórico (transmodalidad), los antecedentes de sus campos intervinientes (surround, ligthrround, y sensurround), los componentes del hardware de la plataforma, y las proyecciones futuras., The article presents a proposal for the realization of acousmatic concerts where intervenes the vision of spatiality and sound dynamics in conjunction with physical/vibration propagates addressed to the public. Through the visual and tactile channels it seeks to emphasize paths surround sound spatialization, as well as dynamic variations made in the composition, or those produced during the re-spatialization by a performer. Finally the motivations of the project, its theoretical basis (crossmodality), the origins of the fields involved (surround, ligthrround, and sensurround), the hardware components of the platform and future projections are described., Sociedad Argentina para las Ciencias Cognitivas de la Música (SACCoM)

The design of a step-zoom telescope and its ability to achieve a diffraction-limited performance is explored. The basic idea is to include digital postprocessing to compensate for changes in the modulation transfer function of the system, assuming the knowledge of the range to the object. The instrument is conformed of a two-mirror telescope, two lenses, and a detector. High-quality images and a zoom telescope that ranges from 22 to 61 f-number is achieved by moving the primary mirror and two lenses. The preliminary calculations for the design process and a simulation that shows the performance of the step-zoom telescope are described.

Protein inclusions made up primarily of misfolded α-synuclein (α-Syn) are the hallmark of a set of disorders known as synucleionopathies, most notably Parkinson’s disease (PD). It is becoming increasingly appreciated that α-Syn misfolding can spread to anatomically connected regions in a prion-like manner. The protein aggregates that ensue are correlated with neurodegeneration in the various yet select neuronal populations that are affected. Recent advances have begun to shed light on the spreading and toxicity mechanisms that may be occurring in PD. Several key emerging themes are arising from this work suggesting that α-Syn mediated neurodegeneration is due to a combination of relative α-Syn expression level, connectivity to affected brain regions, and intrinsic vulnerability to pathology.

A new concept for push–pull active optics is presented, where the push-force is provided by means of individual airbag type actuators and a common force in the form of a vacuum is applied to the entire back of the mirror. The vacuum provides the pull-component of the system, in addition to gravity. Vacuum is controlled as a function of the zenithal angle, providing correction for the axial component of the mirror’s weight. In this way, the push actuators are only responsible for correcting mirror deformations, as well as for supporting the axial mirror weight at the zenith, allowing for a uniform, full dynamic-range behavior of the system along the telescope’s pointing range. This can result in the ability to perform corrections of up to a few microns for low-order aberrations. This mirror support concept was simulated using a finite element model and was tested experimentally at the 2.12 m San Pedro Martir telescope. Advantages such as stress-free attachments, lighter weight, large actuator area, lower system complexity, and lower required mirror-cell stiffness could make this a method to consider for future large telescopes.

Purpose Optic nerve inflammation, demyelination, and axonal loss are all prominent features of optic neuritis. While corticosteroids hasten visual recovery in optic neuritis, no treatment improves final visual outcomes. HE3286 (17α-ethynyl-5-androstene-3β,7β,17β-triol), a synthetic derivative of a natural steroid, β-AET (5-androstene-3β,7β,17β-triol), exerts anti-inflammatory effects in several disease models and has purported neuroprotective effects as well. HE3286's ability to suppress optic neuritis was examined in experimental autoimmune encephalomyelitis (EAE), a model of multiple sclerosis. Methods Experimental autoimmune encephalomyelitis was induced in C57/BL6 mice. Mice were treated daily with intraperitoneal vehicle or 40 mg/kg HE3286. Visual function was assessed by optokinetic responses (OKR) at baseline and every 10 days until euthanasia at 40 days post immunization. Retinas and optic nerves were isolated. Inflammation (hematoxylin and eosin and Iba1 staining), demyelination (Luxol fast blue staining), and axonal loss (neurofilament staining) were assessed in optic nerve sections. Retinal ganglion cells (RGCs) were immunolabeled with Brn3a antibodies to quantify RGC survival. Results Progressive decreases in OKR occurred in vehicle-treated EAE mice, and HE3286 treatment reduced the level of this vision loss. HE3286 also attenuated the degree of inflammation, demyelination, and axonal loss in EAE optic nerves as compared to nerves from vehicle-treated EAE mice. Retinal ganglion cell loss that occurred in both vehicle- and HE3286-treated EAE mice was reduced in the temporal retinal quadrant of HE3286-treated mice. Conclusions HE3286 suppresses inflammation, reduces demyelination and axonal loss, and promotes RGC survival during experimental optic neuritis. Importantly, HE3286 treatment also preserves some RGC function. Results suggest that HE3286 is a potential novel treatment for optic neuritis.

A wave-front coded imaging system is an optical-digital method for aberration control. Wave-front coding technology incorporates an aspheric element in the optical system in order to capture a coded image and by digital processing decode it to obtain the final image. The WFC system is very insensitive to defocus-like aberrations and thereby becomes a tool in the aberration balancing for telescope systems. We propose WFC technology to be implemented in a two spherical mirror telescope. In this work we present the design and simulation of the proposed telescope, trade-offs encountered in the design process and aspects of the image restoration.

An algorithm is presented that accomplishes the optical alignment of Cassegrain and Ritchey‐Chretien astronomical telescopes. The algorithm does an iterative comparison and minimization of the error between the ideal pattern of the transverse aberration, TA, and the actual or measured pattern of the TA of the telescope. The TA is obtained with a Hartmann mask placed on the base plate of the telescope and is detected by a CCD camera near the focal plane.

Numerical simulations of thermal field variation due to land use changes, such as the reduction of the lacustrine system and the growth of the urban area, in the Basin of Mexico are presented. It is shown that the historically recorded warming in the basin could be attributed, not only to the growth of the urban area, but more importantly to the drastic reduction in the lacustrine system that existed in the basin.

We describe observations of the 2.12 μm molecular hydrogen emission in Orion using an IR Fabry-Perot interferometer with a spectral resolution of 24 km s-1 and a 2'' spatial resolution covering a region of 36×36 (0.46×0.46 pc2) that contains the H2 filamentary finger system located to the northwest of the Trapezium. We develop a simple model to explain the observed low-velocity structure as described by its radial moments: intensity, velocity centroid, velocity dispersion, and skewness. We assume a strong wind of 230 km s-1 produced by IRc2 interacting with a set of molecular clumps with density of 5.6×105 cm-3. This simple model provides a good match to the observed moments, gives clues to the development of filaments or fingers and entrainment of the molecular material, and associates the observed high-velocity blueshifted emission to the region. The driving source of the wind requires a high mass-loss rate and thus is likely IRc2. The H2 line emission is produced by a slow J-type shock (20 km s-1) in the clumps with an emissivity proportional to v1.8. Estimates for the total wind mass and clump mass yield 0.5 and 15 M☉ inside a radius of 1' (0.1 pc). The individual clumps have masses and sizes of few ×10−3M☉ and 0.007 pc, respectively. We conclude that the central 0.1 pc region surrounding the BN-KL nebula in front of OMC-1 is in the process of being disrupted by the strong wind of IRc2 on a timescale of 2000 yr.

We present an analysis of the familiar method of analyzing out-of-focus stellar images to align Cassegrain reflector telescopes. We measure the asymmetry in the out-of-focus image as the difference in positions of the centers of the bordering circles. By exact raytracing we find that the asymmetry can be expressed as a linear combination of tip/tilt and displacement of the secondary mirror. Furthermore and surprisingly, the difference in the positions of the centers does not depend on the amount of defocus, and so only two parameters of the linear combination are needed to align the telescope. These parameters depend only on the telescope design parameters. Finally, we report experimental results carried out with the 1.5 m telescope of UNAM, which verify the outlined numerical results. in the recording and fast analysis of the donut. We first present a numerical analysis of the effects of misalignments of the primary and secondary mirrors in the asymmetry of the donut. We show graphs that relate the different misalignments with the asymmetries. We extract from this analysis the required parameters for the alignment of the telescope. We then develop an algorithm that allows one to proceed in the alignment of a telescope. This algorithm detects the edges of the donut and calculates the required tip/tilt corrections. Displacement cor- rections are then performed. 2. NUMERICAL MODEL In an out-of-focus image of a star (donut), the light distri- bution has two edges, an inner and an outer edge. Far enough from the caustic region, these edges are nearly circular. How- ever, for a misaligned telescope, the centers of these circles do not coincide. We will take the difference vector between these centers, , with components ( ), as a measure of the Dr

We present preliminary results of a swordfish bone measurements using the fringe projection technique. A phase correlation algorithm for phase shifting profilometry is compared in performance with the classic Fourier transform approach for phase extraction.

Deterministic hydrodynamic polishing with HyDRa requires a precise control of polishing parameters, such as propelling air pressure, slurry density, slurry flux and tool height. We describe the HyDRa polishing system and prove how precise, deterministic polishing can be achieved in terms of the control of these parameters. The polishing results of an 84 cm hyperbolic mirror are presented to illustrate how the stability of these parameters is important to obtain high-quality surfaces.

In an effort to optimize the hydrodynamic radial (HyDRa) polishing process for applications where the amount of material that has to be removed implies long polishing times, we have developed a method to determine the optimum correction fraction that has to be made for a given error map, in terms of the level of determinism of the process, the number of iterations, and their associated polishing runs as well as run times.

Successful tests and results that confirm an efficient behavior of the new common-pull (controlled vacuum), multiple-push primary mirror cell for the 2.1 m telescope at OAN/SPM, are presented. An optical design program that reduces the information obtained from intra- and extra-focal Hartmann patterns, using the direction cosines of the rays that cross the sampled regions, is discussed. The intrinsic uncertainties of this method are evaluated.

The axon initial segment (AIS) of multipolar vertebrate neurons contains a specialized set of ion channels that allows it to serve as the site for action potential initiation. The AIS is organized by a giant variant of ankyrin G (AnkG) that links ion channels to a specialized cytoskeleton and is required for a plasma membrane diffusion barrier that excludes somatodendritic proteins from the axon. The ankyrin-based AIS has been viewed as a vertebrate adaptation for fast, precise signaling because the giant isoform required for AIS organization is believed to have evolved recently in the vertebrate lineage. Here we re-examine AIS origins with a detailed analysis of giant ankyrin evolution and testing the role of a giant ankyrin in organization of an AIS-like domain in the proximal axon of a model multipolar Drosophila neuron (ddaE). We found giant ankyrins in all major bilaterian phyla, and phylogenetic analysis points to a single origin for the unusual long exon that encodes giant ankyrins in an ancestor of all extant bilaterians. We therefore hypothesized that giant ankyrins may play a conserved role in organization of the proximal axon throughout the Bilateria. We examined this possibility by looking for conserved ankyrin-dependent AIS features in Drosophila ddaE neurons via live imaging. Using a FRAP assay, we found that ddaE neurons have a plasma membrane diffusion barrier in the proximal axon that requires a giant isoform of the neuronal ankyrin ank2. Two voltage-gated K+ channels, elk and shal, concentrate in this proximal axon. We found that the accumulation of shal, like the diffusion barrier, depends on ank2. Our results suggest that the giant ankyrin-based cytoskeleton of the AIS may not be a recent vertebrate innovation, but instead evolved in an ancestral bilaterian soon after the divergence from cnidarians.

This work is a phenomenological attempt to predict the dynamical response of a sand heap due to rotation about its vertical axis. We have attempted experiments and we developed a model in order to describe the effect of the rotation on the pile's surface from a dimensionless force balance equation using Coulomb's law. We obtained good agreement between the experimental patterns and the theory, depending on the material through the solid friction angle, and we gave a plausible mechanism for the way in which the history of the pile is determined by dynamical (Froude number) and material (friction coefficient) parameters.

The Reionization and Transients InfraRed camera (RATIR) is a simultaneous optical/NIR multi-band imaging camera which is 100% time-dedicated to the followup of Gamma-ray Bursts. The camera is mounted on the 1.5-meter Johnson telescope of the Mexican Observatorio Astron

The Reionization And Transients Infra-Red (RATIR) camera is intended for robotic operation on the 1.5-meter Harold Johnson telescope of the Observatorio Astronomico Nacional on the Sierra de San Pedro Martir, Baja California, Mexico. This paper describes the work we have carried out to successfully automate the telescope and prepare it for RATIR. One novelty is our use of real-time absolute astrometry from the finder telescopes to point and guide the main telescope.

We present improvements to the Hydra polishing system that open the possibility to polish high-precision free-form meter-class optics, and advances on a hollow borosilicate 84-cm mirror and the optical metrology necessary to measure this surface.

We present the results of the optical characterization of the mirrors of the telescope of 62cm observatory "SEVERO DIAZ GALINDO" property of the University of Guadalajara. We use the Ronchi test and a spherometer to measure by first time, the radius of curvature for the primary and secondary mirror, the parameters of the telescope system were obtained by using the commercial software ZEMAX. We confirm that both mirrors are adequate to work in the telescope configuration and to do optical astronomy.

A correlation algorithm to recover the phase in phase-shifting interferometry is presented. We make numerical simulations to test the proposed algorithm and apply it to real interferograms with satisfactory results.

In this paper we present the Medium Resolution Spectrograph ESOPO, an instrument designed and built for the 2.1m Telescope at the Observatorio Astronomico Nacional at San Pedro Martir. We discuss the Scientific Goals and the High Level Requirements necessary to translate these goals to optical, mechanical and control specifications. We make an introduction to its conceptual dual-arm design. The optical design is based on a non-classical configuration. The gratings are illuminated in a conical mode working in a quasi Littrow configuration which has the advantage of optimizing the efficiency and the pupil area on the grating. We show here the results of an experimental evaluation of the concept. The optical design, mechanical structure, slit-mask and acquisition system, control systems, and a study of thermal compensators, are discussed briefly, references to more extended contributions in these proceedings are made. The management schematics of the project are briefly discussed.

This work presents the specifications, requirements, design, finite element analysis and results of the assembled subsystems: slit-mask, and the acquisition and guiding zone mechanisms of the ESOPO spectrograph. This spectrograph is a project of the Institute of Astronomy, National University of Mexico.

ESOPO will be a spectrograph of medium resolution for the 2.1 m telescope of the National Observatory at San Pedro Martir, Baja California, Mexico. It has been developed by the Instituto de Astronomia of the Universidad Nacional Autonoma de Mexico (IA-UNAM). The main goal of this instrument is to modernize the capabilities of making science with that particular telescope. It is planned to achieve a spectral resolution between 500 and 5000. ESOPO is split into two arms; each one specialized in a specific wavelength range covering together all the visible light. A very important issue in spectrographs is to avoid inside thermal gradients. Different temperatures in the optical elements produce mechanical movements and image quality degradation during an exposition. The error budget analysis developed for ESOPO allows establishing the required limits for temperature gradients. In this paper is described the thermal analysis of the spectrograph, including specifications, finite element models, thermal equations and expected thermal gradients.

A simple geometrical method to measure the aberration of astigmatism present in the wavefront that emerges from a telescope is presented. The method is based on the analysis of the external contour of the image of a slightly defocused star. An expression elliptical edge is obtained, which links the rms value of Z22 to the geometric parameters of the ellipse. This expression is tested as a function of introduced defocus and astigmatism aberration in telescopes of the San Pedro Martir Observatory. It is shown that the method gives comparable results to wavefront tests, being capable of measuring astigmatism values of approximately 60 nm and larger without the need for auxiliary optics.

We present some experimental results of piston detection by using a classical Ronchi test in a segmented spherical surface. We compare the Ronchi fringes frequency of both segments (reference and under test). When the piston term is present at the segment under test, it is moved iteratively until we obtain a minimum piston error. When the surface is almost cophased, both segments have the same fringe frequency. The fringes of each segment are compared by correlating the intensity versus position in each segment. The Ronchi test is used at the same time as Shack interferometry; this second method is used as a reference to avoid segments tilts. With the Ronchi test we have detected experimentally a piston of the order of 45 nm (lambda/14 with lambda=632.8 nm). This result was compared with images of simulated Ronchigrams.

We present an alternative method for cutting optical glass. It works with a high-pressure fluid, carring abrasive powder. This technique offers some advantages over conventional methods that use diamond abrasive covered wires or disks. We make a critical comparison between those two techniques, characterizing cuts with interferometric, polarimetric, and Ronchi testing. The main feature of the water-jet technique is that it allows surface of any shape, already polished, to be cut safely.