Nonlinearity and pixel shifting effects in HXRG infrared detectors

We study the nonlinearity (NL) in the conversion from charge to voltage in infrared detectors (HXRG) for use in precision astronomy. We present laboratory measurements of the NL function of a H2RG detector and discuss the accuracy to which it would need to be calibrated in future space missions to perform cosmological measurements through the weak gravitational lensing technique. In addition, we present an analysis of archival data from the infrared H1RG detector of the Wide Field Camera 3 in the Hubble Space Telescope that provides evidence consistent with the existence of a sensor effect analogous to the brighter-fatter effect found in Charge-Coupled Devices. We propose a model in which this effect could be understood as shifts in the effective pixel boundaries, and discuss prospects of laboratory measurements to fully characterize this effect.Comment: Accepted for publication in the Journal of Instrumentation (JINST). Part of "Precision Astronomy with Fully Depleted CCDs" (Dec 1-2, 2016), Brookhaven National Laboratory, Upton, NY, US

Activity-dependent competition regulates motor neuron axon pathfinding via PlexinA3

The role of electrical activity in axon guidance has been extensively studied in vitro. To better understand its role in the intact nervous system, we imaged intracellular Ca2+ in zebrafish primary motor neurons (PMN) during axon pathfinding in vivo. We found that PMN generate specific patterns of Ca2+ spikes at different developmental stages. Spikes arose in the distal axon of PMN and were propagated to the cell body. Suppression of Ca2+ spiking activity in single PMN led to stereotyped errors, but silencing all electrical activity had no effect on axon guidance, indicating that an activity-based competition rule regulates this process. This competition was not mediated by synaptic transmission. Combination of PlexinA3 knockdown with suppression of Ca2+ activity in single PMN produced a synergistic increase in the incidence of pathfinding errors. However, expression of PlexinA3 transcripts was not regulated by activity. Our results provide an in vivo demonstration of the intersection of spontaneous electrical activity with the PlexinA3 guidance molecule receptor in regulation of axon pathfinding.Fil: Plazas, Paola Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular; Argentina. University of California at San Diego. Kavli Institute for Brain and Mind. Division of Biological Sciences. Neurobiology Section and Center for Neural Circuits and Behavior; Estados UnidosFil: Nicol, Xavier. University of California at San Diego. Kavli Institute for Brain and Mind. Division of Biological Sciences. Neurobiology Section and Center for Neural Circuits and Behavior; Estados UnidosFil: Spitzer, Nicholas C.. University of California at San Diego. Kavli Institute for Brain and Mind. Division of Biological Sciences. Neurobiology Section and Center for Neural Circuits and Behavior; Estados Unido

The Splashback Feature around DES Galaxy Clusters: Galaxy Density and Weak Lensing Profiles

Splashback refers to the process of matter that is accreting onto a dark matter halo reaching its first orbital apocenter and turning around in its orbit. The clustercentric radius at which this process occurs, r_(sp), defines a halo boundary that is connected to the dynamics of the cluster. A rapid decline in the halo profile is expected near r_(sp). We measure the galaxy number density and weak lensing mass profiles around REDMAPPER galaxy clusters in the first-year Dark Energy Survey (DES) data. For a cluster sample with mean M_(200m) mass ≈2.5 × 10^(14) M⊙, we find strong evidence of a splashback-like steepening of the galaxy density profile and measure r_(sp) = 1.13 ± 0.07 h^(−1) Mpc, consistent with the earlier Sloan Digital Sky Survey measurements of More et al. and Baxter et al. Moreover, our weak lensing measurement demonstrates for the first time the existence of a splashback-like steepening of the matter profile of galaxy clusters. We measure r_(sp) = 1.34 ± 0.21 h^(−1) Mpc from the weak lensing data, in good agreement with our galaxy density measurements. For different cluster and galaxy samples, we find that, consistent with ΛCDM simulations, r_(sp) scales with R_(200m) and does not evolve with redshift over the redshift range of 0.3–0.6. We also find that potential systematic effects associated with the REDMAPPER algorithm may impact the location of r_(sp). We discuss the progress needed to understand the systematic uncertainties and fully exploit forthcoming data from DES and future surveys, emphasizing the importance of more realistic mock catalogs and independent cluster samples

Laboratory Measurement of the Brighter-fatter Effect in an H2RG Infrared Detector

The "brighter-fatter" (BF) effect is a phenomenon—originally discovered in charge coupled devices—in which the size of the detector point-spread function (PSF) increases with brightness. We present, for the first time, laboratory measurements demonstrating the existence of the effect in a Hawaii-2RG HgCdTe near-infrared (NIR) detector. We use JPL's Precision Projector Laboratory, a facility for emulating astronomical observations with UV/VIS/NIR detectors, to project about 17,000 point sources onto the detector to stimulate the effect. After calibrating the detector for nonlinearity with flat-fields, we find evidence that charge is nonlinearly shifted from bright pixels to neighboring pixels during exposures of point sources, consistent with the existence of a BF-type effect. NASAs Wide Field Infrared Survey Telescope (WFIRST) will use similar detectors to measure weak gravitational lensing from the shapes of hundreds of million of galaxies in the NIR. The WFIRST PSF size must be calibrated to ≈0.1% to avoid biased inferences of dark matter and dark energy parameters; therefore further study and calibration of the BF effect in realistic images will be crucial

FPGA-Based High-Speed Optical Fiber Sensor Based on Multitone-Mixing Interferometry

We report a real-time high-speed fiber Bragg grating (FBG) interrogator based on a fiber-optic interferometer. The signal processing is performed by using a low-cost field-programmable gate array (FPGA) system, which is programed to implement a phase-generated carrier (PGC) demodulation algorithm with multitone mixing (MTM) to provide distortion-free signals with high tolerance to modulation depth variations and light intensity fluctuations. The system can stream data at rates up to 1 MS/s and allows multiplexed processing up to two channels. Experimental results show simultaneous measurements of two FBGs, one of which was actuated at frequencies up to 100 kHz. The system features a 3-dB bandwidth of 280 kHz, and a dynamic wavelength resolution of 4.7 fm/Hz ^{mathrm {1/2}}. We also demonstrate a strong reduction of distortion using the MTM approach with respect to the standard technique. Finally, we study the origin of the noise, demonstrating a reduction in common noise sources by using one of the FBGs as a reference. The system can measure FBGs centered at any position within the spectral band of the source, is polarization-independent, and is easily scalable to more than two measurement channels from the same interferometer

Scoping review of studies on food marketing in Latin America: Summary of existing evidence and research gaps

OBJECTIVE: To document the evidence about marketing of ultra-processed foods and “non-alcoholic” beverages in Latin America. METHODS: We performed a structured search of quantitative and qualitative studies in PubMed, SciELO and LILACS, published between January 2000 and May 2017 and conducted in Latin America. We conducted a quality assessment following a standardized tool and a thematic analysis to identify key typologies of marketing across studies RESULTS: Out of 521 studies screened by title and abstract, we included 36 in this review; 27 of them analyzed television advertisement. Other marketing channels studied were food packaging, point of sale and outdoor advertisement. Studies found television advertises foods and beverages that are mostly ultraprocessed foods and have low nutritional value, particularly those promoted during children’s programming. We also observed children have a literal interpretation of images printed on food packaging, so this can be deceiving. Several studies also found proximity to unhealthy foods may increase their consumption. Finally, the thematic analysis identified the following typologies of food marketing: a) television advertisement, b) food packaging marketing, c) marketing strategies at points of sale and d) other marketing strategies. We found almost no advertisements for unprocessed or minimally processed foods such as fruits and vegetables. We did not find any studies on digital marketing conducted in the region. CONCLUSIONS: This review found that the main channel of food marketing was television advertising. This synthesis provides insights to the challenges unhealthy eating represents to the public health of Latin America and identifies knowledge gaps to guide future research

Scoping review of studies on food marketing in Latin America: Summary of existing evidence and research gaps

OBJECTIVE: To document the evidence about marketing of ultra-processed foods and “non-alcoholic” beverages in Latin America. METHODS: We performed a structured search of quantitative and qualitative studies in PubMed, SciELO and LILACS, published between January 2000 and May 2017 and conducted in Latin America. We conducted a quality assessment following a standardized tool and a thematic analysis to identify key typologies of marketing across studies RESULTS: Out of 521 studies screened by title and abstract, we included 36 in this review; 27 of them analyzed television advertisement. Other marketing channels studied were food packaging, point of sale and outdoor advertisement. Studies found television advertises foods and beverages that are mostly ultraprocessed foods and have low nutritional value, particularly those promoted during children’s programming. We also observed children have a literal interpretation of images printed on food packaging, so this can be deceiving. Several studies also found proximity to unhealthy foods may increase their consumption. Finally, the thematic analysis identified the following typologies of food marketing: a) television advertisement, b) food packaging marketing, c) marketing strategies at points of sale and d) other marketing strategies. We found almost no advertisements for unprocessed or minimally processed foods such as fruits and vegetables. We did not find any studies on digital marketing conducted in the region. CONCLUSIONS: This review found that the main channel of food marketing was television advertising. This synthesis provides insights to the challenges unhealthy eating represents to the public health of Latin America and identifies knowledge gaps to guide future research

Secuenciación Parcial del Genoma de Xanthomonas translucens pv. undulosa Empleando Nuevas Tecnologías

La espiga negra o rayado bacteriano es una enfermedad causada por la bacteria Xanthomonas translucens pv. undulosa. Esta enfermedad se manifiesta sobre las hojas con manchas estriadas marrones, mientras que los granos y tallos adquieren un aspecto marrón oscuro de apariencia húmeda. Se manifiesta en cultivos de trigo (Triticum spp), cebada (Hordeum vulgare), centeno (Secale cereale) y avena (Avena sp), donde las epidemias son de carácter esporádico, dependiendo del manejo del cultivo, condiciones climáticas y genotipos utilizados. Eventualmente podrían representar una limitante para la producción en estos cultivos.Hasta el momento, no se ha secuenciado ningún aislamiento de esta bacteria en Argentina, limitando estudio y comprensión de su patogenicidad. Con el objetivo de conocer aspectos genómicos básicos de dicha bacteria, se purificó ADN a partir de colonias aisladas a partir de trigo con síntomas y se secuenció empleando la tecnología MinION (Oxford Nanopore), de pequeño tamaño y bajo costo. Como resultado se obtuvieron 2.9x103 lecturas contabilizando un total de 500Mb secuenciados. En el ensamblaje final se obtuvo un solo contig de aproximadamente 4.5Mb con una cobertura promedio de 70X y con una identidad a nivel de nucleótidos cercanas al 96% respecto de la secuencia referencia de Xanthomonas translucens pv. undulosa cepa ICMP11055 (CP009750). En el proceso de anotación de genes se identificaron 6 rDNA, 57 RNAt y más de 5000 CDSs (secuencias codificantes). Se continúa trabajando en la determinación del repertorio de genes que codifican para proteínas efectorasy otras regiones genómicas asociadas a la patogenicidad.Los resultados expuestos permiten valorar el empleo de las nuevas tecnologías de secuenciación para el conocimiento de diferentes genomas. Las mismas deben ser consideradas como una herramienta económicamente accesible, versátiles ya que no requieren de equipo pesado ni condiciones exigentes para su uso y rápidas, indispensables para el estudio de diferentes agentes fitopatógenos

First report of Oxalis conorrhiza as alternate host of Puccinia sorghi, causal agent of common rust of Maize

A high genetic variability has been recognized in Puccinia sorghi in Argentina (Gonzalez et al. 2011), although its origin remains unclear since the different reported alternate hosts (Oxalis corniculata L., O. stricta L., O. bowiei Herb. ex Lindl.) have never been detected with this disease in the region. In the spring of 2013 and 2014, the spermagonium and aecial estages of a Puccina sp., were observed on O. conorrhiza Jacq. (syn. O. cordobensis R. Knuth) in Córdoba Province, in central Argentina. Those structures were found in 22 sampling sites, under natural infections, in a radius of 175 km of Córdoba City. O. conorrhiza is a bulbous perennial plant native to South America in the Oxalidaceae family, with a low, moderate growth habit. It is distributed in several provinces of central Argentina. O. conorrhiza can usually be found in alluvial flatlands, riverbanks, wasteland, roadsides, pastures, as well as farmlands. The confirmation of the O. conorrhiza species was carried out by the ACCOR Herbarium of the National University of Córdoba, Argentina. On approximately one-third of the leaves of each infected plant, ampulliform, subepidermal, amphigenous spermagonia, arranged in small clusters of 0.5 mm were observed. Spermagonia containing spermatia and receptive hyphae were golden yellow to orange yellow with abundant nectar exuding. Those in the center of the lesion are surrounded by annular groups of aecia, formed exclusively on the abaxial surface of the leaves. Aecia were orange, cylindrical short, with irregular opening at the apex. To determine the causal organism, aesciospores were inoculated in sweet corn plants. Fifty aeciospores from disease samples were suspended per ml of sterile water and sprayed on 5 sweet corn plants. As a negative control, 5 plants were inoculated with sterile water. All plants were kept in the dark at saturated humidity for 24 h at 24°C. After that, the plants were kept at 25 to 27°C and 70 to 80% humidity with a photoperiod of 16 h light. Seven days after inoculation, typical symptoms of corn common rust were observed: orange uredia with abundant urediospores production. At 21 days, typical teleutospores were observed. The rust matched the morphological characteristics of P. sorghi Schwein (Lindquist 1982). DNA from aeciospores from O. conorrhiza was extracted with NucleoSpin Plant II kit. A fragment from the 28S subunit regions rRNA gene was amplified and sequenced with primers Rust1 and F36 (Kropp et al. 1995). BLAST analysis of 28S sequence data (GenBank Accession Nos. HQ412650.1, GU057994.1, and AY114291.1) showed 99% identity to P. sorghi. To our knowledge, this is the first report of P. sorghi isolated from O. conorrhiza worldwide. The report contributes to an improved understanding of variability of P. sorghi which will be useful for exploring appropriate disease management, epidemiology, and breeding strategies.Fil: Guerra, Fernando Andres. Universidad Católica de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Brücher, Elsa. Universidad Católica de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: de Rossi, Roberto Luis. Universidad Católica de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Plazas, M. C.. Universidad Católica de Córdoba; ArgentinaFil: Guerra, Gustavo Dario. Universidad Católica de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ducasse, Daniel Adrián. Universidad Católica de Córdoba; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; Argentin