Random periodic sampling patterns for shift-invariant spaces

We consider multi-variate signals spanned by the integer shifts of a set of generating functions with distinct frequency profiles and the problem of reconstructing them from samples taken on a random periodic set. We show that such a sampling strategy succeeds with high probability provided that the density of the sampling pattern exceeds the number of frequency profiles by a logarithmic factor. The signal model includes bandlimited functions with multi-band spectra. While in this well-studied setting delicate constructions provide sampling strategies that meet the information theoretic benchmark of Shannon and Landau, the sampling pattern that we consider provides, at the price of a logarithmic oversampling factor, a simple alternative that is accompanied by favorable a priori stability margins (snug frames). More generally, we also treat bandlimited functions with arbitrary compact spectra, and different measures of its complexity and approximation rates by integer tiles. At the technical level, we elaborate on recent work on relevant sampling, with the key difference that the reconstruction guarantees that we provide hold uniformly for all signals, rather than for a subset of well-concentrated ones. This is achieved by methods of concentration of measure formulated on the Zak domain

Plan de negocio para el desarrollo de una plataforma de integraci?n entre alumnos y tutores-mentores EDUKT+

La presente tesis desarrolla con el objetivo de crear un modelo de negocio denominado EDUKT+ que integre alumnos /usuarios y profesores/tutores para lograr la realizaci?n de clases particulares de manera eficiente a trav?s de una plataforma digital (aplicaci?n m?vil) bajo el modelo market place y two sided market en cuyo caso, los profesores/tutores ofrecen sus servicios para ser contratados por los alumnos/usuarios. El objetivo principal Se utiliz? Design Thinking como m?todo para entender los verdaderos problemas que tiene el usuario o proveedor (consumidor - proveedor) logrando establecer el problema real y proponer soluciones que puedan ser validadas en la siguiente etapa del proyecto de tesis. Asimismo, se complementa con las metodolog?as de Lean Startup y Agile para echar andar la empresa en la implementaci?n de los planes. Estas herramientas se utilizan transversalmente en la metodolog?a propuesta y adaptada para el Plan de negocios. Se utiliz? la herramienta de benchmarking nacional e internacional de los competidores afines con el modelo propuesto y se delimit? el mercado objetivo a clases particulares para alumnos de niveles inicial, primaria y secundaria ubicados geogr?ficamente en las zonas distritales 2, 6 y 7 de Lima

Parámetros morfométricos del espermatozoide de alpaca (Vicugna pacos), obtenidos por tres métodos de colección

Sperm morphology is essential in evaluating seminal quality and important for fertility prediction in breeding males. The aim of this study was to compare the morphometric parameters of alpaca sperm, collected using three methods of semen extraction, recovery of the vas deferens (DCD), electro ejaculation (EE) and vaginal aspira-tion (VA). The collection was made of 3 animals by each method. The mobility, concentration, vitality, mem-brane functionality and sperm morphometry parameters were determined in a computerized semen analysis kit – ISAS® CASA - Morph. For morphometric parameters, semen samples were processed with a Hemacolor® stain-ing kit and viewed under a phase-contrast microscope. For each sample, at least 200 sperm were captured at random, with an image resolution of 0.08 μm per pixel on the horizontal and vertical axes. The comparison of the morphometric parameters between the collection method and the animal was carried out using a random block design. Total motility was 16.27±11.96%, 14.68±11.21% and 12.44±7.27%; the sperm concentration of 247±186.70x106EPZ/mL, 67.92±67.92x106EPZ/mL and 100.32±56.13x106EPZ/mL, the vitality was 62.86 ±15.92%, 63±15.21% and 70.16±14.33% in sperm collected by DCD, EE and AV respectively. Regarding the morphometric parameters, a length of 5.49±0.43μm, 5.53±0.41μm and 5.75±0.53μm was found, area 14.30±2.00 μm2, 15.05±1.77 μm2 and 15.88±2.00 μm2, perimeter of 16.10±1.31μm, 17.11±1.20μm and 17.41 ± 1.43, width of 3.22±0.27μm, 3.30±0.32μm and 3.33±0.25μm and the acrosome percentage of 52.22±7.82μm, 49.52±7.47μm and 47.44±5.77μm in sperm collected by DCD, EE and AV respectively. The morphometric parameters of the size and shape of the sperm head and the intermediate piece showed significant statistical differences (p <0.01) between the collection methods and between the animals. In conclusion, the morphometric parameters of alpaca spermatozoa were influenced by collection method, and show variations between animals.La morfología espermática es esencial en la evaluación de la calidad seminal e importante para la predicción de la fertilidad de machos reproductores. El objetivo del presente estudio fue comparar los parámetros morfométri-cos de espermatozoides de alpaca, obtenidos por tres métodos de extracción de semen, la recuperación del con-ducto deferente (DCD), electroeyaculación (EE) y aspiración vaginal (AV). La colección se realizó de 3 anima-les por cada método. Se determinó la movilidad, concentración, vitalidad, funcionalidad de membrana y paráme-tros de morfometría espermática, con un equipo de análisis computarizado de semen - ISAS® CASA - Morph. Para los parámetros morfométricos, las muestras de semen se procesaron con un kit de tinción Hemacolor® y se observaron en un microscopio de contraste de fases. Por cada muestra, se capturaron al menos 200 espermato-zoides al azar, con resolución de imágenes de 0.08 μm por píxel en los ejes horizontal y vertical. La motilidad total fue de 16.27±11.96%, 14.68±11.21% y 12.44±7.27%, la concentración espermática de 247±186.70 x 106EPZ/mL, 67.92±67.92 x 106EPZ/mL y 100.32±56.13 x 106EPZ/mL, la vitalidad fue 62.86±15.92%, 63±15.21% y 70.16±14.33% en espermatozoides colectados por DCD, EE y AV respectivamente. En cuanto a los parámetros morfométricos se encontró una longitud de 5.49±0.43 μm, 5.53±0.41μm y 5.75±0.53μm, área 14.30±2.0μm2, 15.05±1.77μm2 y 15.88±2.0μm2, perímetro de 16.10±1.31μm, 17.11±1.20μm y 17.41±1.43μm, ancho de 3.22±0.27μm, 3.30±0.32μm y 3.33±0.25 μm y el porcentaje de acrosoma de 52.22±7.82%, 49.52±7.47% y 47.44±5.77% en espermatozoides colectados por DCD, EE y AV respectivamente. La compara-ción de los parámetros morfométricos entre método de colecta y animal se realizó mediante un diseño de bloques alzar. Los parámetros morfométricos del tamaño y forma de la cabeza de espermatozoide, y pieza intermedia mostraron diferencias estadísticas significativas (p<0.01) entre métodos de colección y entre animal. En conclu-sión, los parámetros morfométricos del espermatozoide de alpaca son influidos por el método de colección, y muestran variación entre animales

Optical Photometry of the Type Ia SN 1999ee and the Type Ib/c SN 1999ex in IC 5179

We present UBVRIz lightcurves of the Type Ia SN 1999ee and the Type Ib/c SN 1999ex, both located in the galaxy IC 5179. SN 1999ee has an extremely well sampled lightcurve spanning from 10 days before Bmax through 53 days after peak. Near maximum we find systematic differences ~0.05 mag in photometry measured with two different telescopes, even though the photometry is reduced to the same local standards around the supernova using the specific color terms for each instrumental system. We use models for our bandpasses and spectrophotometry of SN 1999ee to derive magnitude corrections (S-corrections) and remedy this problem. This exercise demonstrates the need of accurately characterizing the instrumental system before great photometric accuracies of Type Ia supernovae can be claimed. It also shows that this effect can have important astrophysical consequences since a small systematic shift of 0.02 mag in the B-V color can introduce a 0.08 mag error in the extinction corrected peak B magnitudes of a supernova and thus lead to biased cosmological parameters. The data for the Type Ib/c SN 1999ex present us with the first ever observed shock breakout of a supernova of this class. These observations show that shock breakout occurred 18 days before Bmax and support the idea that Type Ib/c supernovae are due to core collapse of massive stars rather than thermonuclear disruption of white dwarfs.Comment: 55 pages, 15 figures, accepted by the Astronomical Journa

The 3D Bioprinted Scaffolds for Wound Healing

Skin tissue engineering and regeneration aim at repairing defective skin injuries and progress in wound healing. Until now, even though several developments are made in this field, it is still challenging to face the complexity of the tissue with current methods of fabrication. In this review, short, state-of-the-art on developments made in skin tissue engineering using 3D bioprinting as a new tool are described. The current bioprinting methods and a summary of bioink formulations, parameters, and properties are discussed. Finally, a representative number of examples and advances made in the field together with limitations and future needs are provided

UBVRIz Light Curves of 51 Type II Supernovae

We present a compilation of UBV RIz light curves of 51 type II supernovae discovered during the course of four different surveys during 1986 to 2003: the Cerro Tololo Supernova Survey, the Calan/Tololo Supernova Program (C&T), the Supernova Optical and Infrared Survey (SOIRS), and the Carnegie Type II Supernova Survey (CATS). The photometry is based on template-subtracted images to eliminate any potential host galaxy light contamination, and calibrated from foreground stars. This work presents these photometric data, studies the color evolution using different bands, and explores the relation between the magnitude at maximum brightness and the brightness decline parameter (s) from maximum light through the end of the recombination phase. This parameter is found to be shallower for redder bands and appears to have the best correlation in the B band. In addition, it also correlates with the plateau duration, being thus shorter (longer) for larger (smaller) s values.Comment: 110 pages, 9 Figures, 6 Tables, accepted in A

Optical and Infrared Photometry of the Nearby Type Ia Supernovae 1999ee, 2000bh, 2000ca, and 2001ba

We present near infrared photometry of the Type Ia supernova 1999ee; also, optical and infrared photometry of the Type Ia SNe 2000bh, 2000ca, and 2001ba. For SNe 1999ee and 2000bh we present the first-ever SN photometry at 1.035 microns (the Y-band). We present K-corrections which transform the infrared photometry in the observer's frame to the supernova rest frame. Using our infrared K-corrections and stretch factors derived from optical photometry, we construct JHK templates which can be used to determine the apparent magnitudes at maximum if one has some data in the window -12 to +10 d with respect to T(B_max). Following up previous work on the uniformity of V minus IR loci of Type Ia supernovae of mid-range decline rates, we present unreddened loci for slow decliners. We also discuss evidence for a continuous change of color at a given epoch as a function of decline rate.Comment: 53 pages, 14 figures, to be published in the March 2004 issue of the Astronomical Journa