We study the 37 brightest radio sources in the Subaru/XMM-Newton Deep Field (SXDF). We have spectroscopic redshifts for 24 of 37 objects and photometric redshifts for the remainder, yielding a median ...redshift z_med for the whole sample of z_med ~= 1.1 and a median radio luminosity close to the `FRI/FRII' luminosity divide. Using mid-IR (Spitzer MIPS 24 um) data we expect to trace nuclear accretion activity, even if it is obscured at optical wavelengths, unless the obscuring column is extreme. Our results suggest that above the FRI/FRII radio luminosity break most of the radio sources are associated with objects that have excess mid-IR emission, only some of which are broad-line objects, although there is one clear low-accretion-rate object with an FRI radio structure. For extended steep-spectrum radio sources, the fraction of objects with mid-IR excess drops dramatically below the FRI/FRII luminosity break, although there exists at least one high-accretion-rate `radio-quiet' QSO. We have therefore shown that the strong link between radio luminosity (or radio structure) and accretion properties, well known at z ~ 0.1, persists to z ~ 1. Investigation of mid-IR and blue excesses shows that they are correlated as predicted by a model in which, when significant accretion exists, a torus of dust absorbs ~30% of the light, and the dust above and below the torus scatters >~1% of the light.
We present results from the earliest observations of DEBRIS, a Herschel Key Programme to conduct a volume- and flux-limited survey for debris discs in A-type through M-type stars. PACS images (from ...chop/nod or scan-mode observations) at 100 and 160 micron are presented toward two A-type stars and one F-type star: beta Leo, beta UMa and eta Corvi. All three stars are known disc hosts. Herschel spatially resolves the dust emission around all three stars (marginally, in the case of beta UMa), providing new information about discs as close as 11 pc with sizes comparable to that of the Solar System. We have combined these data with existing flux density measurements of the discs to refine the SEDs and derive estimates of the fractional luminosities, temperatures and radii of the discs.
ABSTRACT
We report the first ground-based detection of the water line p-H2O (211–202) at 752.033 GHz in three z < 0.08 ultraluminous infrared galaxies (ULIRGs): IRAS 06035-7102, IRAS 17207-0014, and ...IRAS 09022-3615. Using the Atacama Pathfinder EXperiment (APEX), with its Swedish-ESO PI Instrument for APEX (SEPIA) band-9 receiver, we detect this H2O line with overall signal-to-noise ratios of 8–10 in all three galaxies. Notably, this is the first detection of this line in IRAS 06035-7102. Our new APEX-measured fluxes, between 145 and 705 Jy km s−1, are compared with previous values taken from Herschel SPIRE FTS. We highlight the great capabilities of APEX for resolving the H2O line profiles with high spectral resolutions while also improving by a factor of two the significance of the detection within moderate integration times. While exploring the correlation between the p-H2O(211–202) and the total infrared luminosity, our galaxies are found to follow the trend at the bright end of the local ULIRG’s distribution. The p-H2O(211–202) line spectra are compared to the mid-J CO and HCN spectra, and dust continuum previously observed with ALMA. In the complex interacting system IRAS 09022-3615, the profile of the water emission line is offset in velocity with respect to the ALMA CO(J = 4–3) emission. For IRAS 17207-0014 and IRAS 06035-7102, the profiles between the water line and the CO lines are spectroscopically aligned. This pilot study demonstrates the feasibility of directly conducting ground-based high-frequency observations of this key water line, opening the possibility of detailed follow-up campaigns to tackle its nature.
This study aimed to describe the interannual climate variability in the West Antarctic Peninsula (WAP) under austral summer conditions. Time series of January sea-surface temperature (SST) at 1 km ...spatial resolution from satellite-based multi-sensor data from Moderate Resolution Imaging Spectrometer (MODIS) Terra, MODIS Aqua, and Visible Infrared Imager Radiometer Suite (VIIRS) were compiled between 2001 and 2020 at localities near the Gerlache Strait and the Carlini, Palmer, and Rothera research stations. The results revealed a well-marked spatial-temporal variability in SST at the WAP, with a one-year warm episode followed by a five-year cold episode. Warm waters (SST > 0 °C) reach the coast during warm episodes but remain far from the shore during cold episodes. This behavior of warm waters may be related to the regional variability of the Antarctic Circumpolar Current, particularly when the South Polar Front (carrying warm waters) reaches the WAP coast. The WAP can be divided into two zones representing two distinct ecoregions: the northern zone (including the Carlini and Gerlache stations) corresponds to the South Shetland Islands ecoregion, and the southern zone (including the Palmer and Rothera stations) corresponds to the Antarctic Peninsula ecoregion. The Gerlache Strait is likely situated on the border between the two ecoregions but under a greater influence of the northern zone. Our data showed that the Southern Annular Mode (SAM) is the primary driver of SST variability, while the El Niño Southern Oscillation (ENSO) plays a secondary role. However, further studies are needed to better understand regional climate variability in the WAP and its relation with SAM and ENSO; such studies should use an index that adequately describes the ENSO in these latitudes and addresses the limitations of the databases used for this purpose. Multi-sensor data are useful in describing the complex climate variability resulting from the combination of local and regional processes that elicit different responses across the WAP. It is also essential to continue improving SST approximations at high latitudes.
In this study, we report the response of phytoplankton community composition to cold and warm interannual events affecting the waters off the Baja California Peninsula from 2007 to 2016 based on data ...obtained from a single marine station (31.75° N/116.96° W). Included variables were satellite chlorophyll a, sea surface temperature (MODIS/Aqua), upwelling intensity, and field data (phytoplankton pigments, inorganic nutrients, light penetration). Phytoplankton pigments were determined by high performance liquid chromatography, and CHEMTAX software was used to determine the relative contributions of the main taxonomic groups to chlorophyll a. Our results confirm the decrease in phytoplankton biomass due to the influence of the recent Pacific Warm Anomaly (2014) and El Niño 2015–2016. However, this decrease was especially marked at the surface. When data from the entire water column was considered, this decrease was not significant, because at the subsurface Chla did not decrease as much. Nevertheless, significant changes in community composition occurred in the entire water column with Cyanobacteria (including Prochlorococcus) and Prymnesiophytes being dominant at the surface, while Chlorophytes and Prasinophytes made a strong contribution at the subsurface. Analysis of the spatial distribution of SST and satellite chlorophyll a made it possible to infer the spatial extension of these anomalies at a regional scale.
La presente investigación tiene como objetivo analizar la incidencia de la diversidad del directorio en la adopción de prácticas de gestión y control de riesgos de 236 sociedades anónimas chilenas ...durante el periodo 2015-2019. Para ello, se realizó un estudio descriptivo-correlacional, considerando la diversidad de género, nacionalidad y edad del directorio, como también el grado de adopción a las practicas de gestión y control de riesgo, propuestas por el regulador local. A través de un análisis de regresión entre las variables de estudio, se observó que la diversidad de género y nacionalidad incide positiva y significativamente en la adopción de prácticas de gestión y control de riesgos, no así la diversidad de edad, la cual no tiene un impacto significativo en la adopción de prácticas de gestión y control de riesgos. Además, se concluyó que los directorios no presentan una tendencia hacia la heterogeneidad en su conformación, estando compuestos en su mayoría por consejeros de género masculino, de nacionalidad chilena y en un rango etario entre los 50 y 70 años, dejando en evidencia el estancamiento en las tasas de diversidad de este órgano tomador de decisiones, como también la baja adopción de prácticas corporativas relacionadas al control y gestión de riesgos en las principales empresas del mercado accionario chileno.
The objective of this study is to analyze the incidence of board diversity in the adoption of management practices and risk control of 236 Chilean public limited companies in the period 2015- 2019. ...For this, a descriptive-correlational study was carried out, considering the diversity of gender, nationality, and age of the board of directors, and the degree of adoption of risk management and control practices proposed by the local regulator. Through a regression analysis between the study variables, it was shown that diversity of gender and nationality has a positive and significant impact on the adoption of risk management and control practices, but not age diversity, which does not have a significant impact on the adoption of risk management and control practices. It was concluded that the boards do not present a tendency towards heterogeneity in their conformation, being composed chiefly of male directors of Chilean nationality and in an age range between 50 and 70 years, leaving evidence of stagnation in the diversity rates of this decision-making body, as well as the low adoption of corporate practices related to risk control and management in companies in the Chilean stock market.
Con el propósito de determinar la biomasa y la composición del fitoplancton (picofitoplancton, nanodiatomeas y microdiatomeas) bajo condiciones oligotróficas, se realizó un estudio en la capa ...superficial de la cuenca de Guaymas, golfo de California, durante el verano tardío de 2016. El estudio contempló la medición de variables hidrográficas, químicas y biológicas en la capa superficial del área de estudio. Nuestros resultados mostraron una columna de agua cálida, fuertemente estratificada, empobrecida en nutrientes y con biomasas fitoplanctónicas reducidas (<1 mg Cla·m–3). Los cocientes promedio de N:P (0.55 ± 1.34), N:Si (0.13 ± 0.18) y Fe:N (52.70 ± 29.70) indicaron condiciones de limitación por N. La contribución de los grupos fitoplanctónicos a la biomasa fluctuó ampliamente por nivel de profundidad, y se observó el predominio del picofitoplancton (85.0 ± 2.7%) en superficie (5 m) y de las nano-microdiatomeas (91.5 ± 5.9%) en el nivel más profundo (35-40 m), adyacente a la termoclina. Las diatomeas dominaron la biomasa integrada entre la superficie y 50 m de profundidad, con una contribución promedio ~6 veces mayor que la del picofitoplancton. A pesar de que se registraron condiciones ideales para la proliferación de cianobacterias diazótrofas, la presencia de Trichodesmium spp. y Richelia intracellularis fue muy irregular y en abundancias relativamente bajas (2,220 ± 1,575 célula·L–1). Nuestros resultados son especialmente relevantes, ya que sugieren que, bajo condiciones de limitación por N, el paradigma de la alta biomasa y dominancia de células grandes en el golfo de California puede verse desafiado durante la temporada de verano.
Abstract In order to determine the structure and biomass of phytoplankton (picophytoplankton, nanodiatoms, and microdiatoms) under oligotrophic conditions, a study was carried out in the surface ...layer of the Guaymas Basin, Gulf of California, during the late summer of 2016. This study included the measurement of hydrographic, chemical, and biological variables in the surface layer of the study area. Our results showed a warm, strongly stratified, and nutrient-depleted water column associated with reduced phytoplankton biomass (<1 mg Chla·m-3). The average ratios of N:P (0.55 ± 1.34), N:Si (0.13 ± 0.18), and Fe:N (52.70 ± 29.70) indicate N-limiting conditions. The biomass contribution of phytoplankton groups fluctuated widely by depth level, with predominance of picophytoplankton (85.0 ± 2.7%) at the surface (5 m) and nano-microdiatoms (91.5 ± 5.9%) at the deepest level (35-40 m), adjacent to the thermocline. Diatoms dominated the integrated biomass between the surface and 50-m depth, with an average contribution ~6 times greater than that of picophytoplankton. Despite the ideal conditions for the proliferation of diazotrophs, the presence of Trichodesmium spp. and Richelia intracellularis was very irregular and in relatively low abundances (2,220 ± 1,575 cell·L-1). Our results are especially relevant as they suggest that, under N-limiting conditions, the paradigm of high biomass and large cell dominance in the Gulf of California may be challenged during the summer season.
The human body is a complex system maintained in homeostasis thanks to the interactions between multiple physiological regulation systems. When faced with physical or biological perturbations, this ...system must react by keeping a balance between adaptability and robustness. The SARS-COV-2 virus infection poses an immune system challenge that tests the organism's homeostatic response. Notably, the elderly and men are particularly vulnerable to severe disease, poor outcomes, and death. Mexico seems to have more infected young men than anywhere else. The goal of this study is to determine the differences in the relationships that link physiological variables that characterize the elderly and men, and those that characterize fatal outcomes in young men. To accomplish this, we examined a database of patients with moderate to severe COVID-19 (471 men and 277 women) registered at the "Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán" in March 2020. The sample was stratified by outcome, age, and sex. Physiological networks were built using 67 physiological variables (vital signs, anthropometric, hematic, biochemical, and tomographic variables) recorded upon hospital admission. Individual variables and system behavior were examined by descriptive statistics, differences between groups, principal component analysis, and network analysis. We show how topological network properties, particularly clustering coefficient, become disrupted in disease. Finally, anthropometric, metabolic, inflammatory, and pulmonary cluster interaction characterize the deceased young male group.
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