Characterization and correction of charge-induced pixel shifts in DECam

Interaction of charges in CCDs with the already accumulated charge distribution causes both a flux dependence of the point-spread function (an increase of observed size with flux, also known as the brighter/fatter effect) and pixel-to-pixel correlations of the Poissonian noise in flat fields. We describe these effects in the Dark Energy Camera (DECam) with charge dependent shifts of effective pixel borders, i.e. the Antilogus et al. (2014) model, which we fit to measurements of flat-field Poissonian noise correlations. The latter fall off approximately as a power-law r^-2.5 with pixel separation r, are isotropic except for an asymmetry in the direct neighbors along rows and columns, are stable in time, and are weakly dependent on wavelength. They show variations from chip to chip at the 20% level that correlate with the silicon resistivity. The charge shifts predicted by the model cause biased shape measurements, primarily due to their effect on bright stars, at levels exceeding weak lensing science requirements. We measure the flux dependence of star images and show that the effect can be mitigated by applying the reverse charge shifts at the pixel level during image processing. Differences in stellar size, however, remain significant due to residuals at larger distance from the centroid.Comment: typo and formatting fixes, matches version published in JINS

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

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

Reformulation of packaged foods and beverages in the Colombian food supply

Q1Q1Public discussion, advocacy, and legislative consideration of policies aimed at reducing consumption of processed foods, such as sugar-sweetened beverage (SSB) taxes and mandatory front-of-package (FOP) warning labels, may stimulate product reformulation as a strategy to prevent regulation. In Colombia, there have been major legislative pushes for SSB taxes and FOP labels, although neither has passed to date. In light of the ongoing policy debate and successful implementation of similar policies in Peru and Chile, we explored manufacturer reformulation in the Colombian food supply. We compared the quantities of nutrients of concern (including sugar, sodium, and saturated fat) from the nutrition facts panels of the same 102 packaged foods and 36 beverages from the top-selling brands in Colombia between 2016 and 2018. Our analyses showed a substantial decrease in median sugar content of beverages, from 9.2 g per 100 mL to 5.2 g per 100 mL, and an increase in the percentage of beverages containing non-nutritive sweeteners (NNS), from 33% to 64% (p = 0.003). No meaningful changes in the quantities of nutrients of concern among foods were observed. Our findings suggest little reformulation has occurred in Colombia in the absence of mandatory policies, except for the substitution of sugar with NNS among beverages.Revista Internacional - Indexad

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