First observations and magnitude measurement of Starlink's Darksat

Measure the Sloan g' magnitudes of the Starlink's STARLINK-1130 (Darksat) and 1113 LEO communication satellites and determine the effectiveness of the Darksat darkening treatment at 475.4\,nm. Two observations of the Starlink's Darksat LEO communication satellite were conducted on 2020/02/08 and 2020/03/06 using a Sloan r' and g' filter respectively. While a second satellite, STARLINK-1113 was observed on 2020/03/06 using a Sloan g' filter. The initial observation on 2020/02/08 was a test observation when Darksat was still manoeuvring to its nominal orbit and orientation. Based on the successful test observation, the first main observation was conducted on 2020/03/06 along with an observation of the second Starlink satellite. The calibration, image processing and analysis of the Darksat Sloan g' image gives an estimated Sloan g' magnitude of $7.46\pm0.04$ at a range of 976.50\,km. For STARLINK-1113 an estimated Sloan g' magnitude of $6.59\pm0.05$ at a range of 941.62\,km was found. When scaled to a range of 550\,km and corrected for the solar and observer phase angles, a reduction by a factor of two is seen in the reflected solar flux between Darksat and STARLINK-1113. The data and results presented in this work, show that the special darkening coating used by Starlink for Darksat has darkened the Sloan g' magnitude by $0.77\pm0.05$\,mag, when the range is equal to a nominal orbital height (550\,km). This result will serve members of the astronomical community modelling the satellite mega-constellations, to ascertain their true impact on both the amateur and professional astronomical communities. Concurrent and further observations are planned to cover the full optical and NIR spectrum, from an ensemble of instruments, telescopes and observatories.Comment: Accepted for publication in A&A Letters. 5 pages, 2 figures and 4 table

739 observed NEAs and new 2-4m survey statistics within the EURONEAR network

We report follow-up observations of 477 program Near-Earth Asteroids (NEAs) using nine telescopes of the EURONEAR network having apertures between 0.3 and 4.2 m. Adding these NEAs to our previous results we now count 739 program NEAs followed-up by the EURONEAR network since 2006. The targets were selected using EURONEAR planning tools focusing on high priority objects. Analyzing the resulting orbital improvements suggests astrometric follow-up is most important days to weeks after discovery, with recovery at a new opposition also valuable. Additionally we observed 40 survey fields spanning three nights covering 11 sq. degrees near opposition, using the Wide Field Camera on the 2.5m Isaac Newton Telescope (INT), resulting in 104 discovered main belt asteroids (MBAs) and another 626 unknown one-night objects. These fields, plus program NEA fields from the INT and from the wide field MOSAIC II camera on the Blanco 4m telescope, generated around 12,000 observations of 2,000 minor planets (mostly MBAs) observed in 34 square degrees. We identify Near Earth Object (NEO) candidates among the unknown (single night) objects using three selection criteria. Testing these criteria on the (known) program NEAs shows the best selection methods are our epsilon-miu model which checks solar elongation and sky motion and the MPC's NEO rating tool. Our new data show that on average 0.5 NEO candidates per square degree should be observable in a 2m-class survey (in agreement with past results), while an average of 2.7 NEO candidates per square degree should be observable in a 4m-class survey (although our Blanco statistics were affected by clouds). At opposition just over 100 MBAs (1.6 unknown to every 1 known) per square degree are detectable to R=22 in a 2m survey based on the INT data, while our two best ecliptic Blanco fields away from opposition lead to 135 MBAs (2 unknown to every 1 known) to R=23.Comment: Published in Planetary and Space Sciences (Sep 2013

The stellar occultation by Makemake on 2011 April 23

We have taken advantage of a stellar occultation by the dwarf planet Makemake on 2011 April 23, to determine several of its main physical properties. We present results from a multisite campaign with 8 positive occultation detections from 5 different sites, including data from the 8-m VLT and 3.5-m NTT telescopes in Chile, which have very high temporal resolution. Because the star was significantly fainter than Makemake (setting a record in the magnitude of a star whose occultation has been detected), the occultation resulted in a drop of just ~0.3 mag in the lightcurves. From the lightcurves we have been able to determine the size and shape of the body, its geometric albedo and constraints on its atmosphere

Staphylococcus aureus infection dynamics

Staphylococcus aureus is a human commensal that can also cause systemic infections. This transition requires evasion of the immune response and the ability to exploit different niches within the host. However, the disease mechanisms and the dominant immune mediators against infection are poorly understood. Previously it has been shown that the infecting S. aureus population goes through a population bottleneck, from which very few bacteria escape to establish the abscesses that are characteristic of many infections. Here we examine the host factors underlying the population bottleneck and subsequent clonal expansion in S. aureus infection models, to identify underpinning principles of infection. The bottleneck is a common feature between models and is independent of S. aureus strain. Interestingly, the high doses of S. aureus required for the widely used "survival" model results in a reduced population bottleneck, suggesting that host defences have been simply overloaded. This brings into question the applicability of the survival model. Depletion of immune mediators revealed key breakpoints and the dynamics of systemic infection. Loss of macrophages, including the liver Kupffer cells, led to increased sensitivity to infection as expected but also loss of the population bottleneck and the spread to other organs still occurred. Conversely, neutrophil depletion led to greater susceptibility to disease but with a concomitant maintenance of the bottleneck and lack of systemic spread. We also used a novel microscopy approach to examine abscess architecture and distribution within organs. From these observations we developed a conceptual model for S. aureus disease from initial infection to mature abscess. This work highlights the need to understand the complexities of the infectious process to be able to assign functions for host and bacterial components, and why S. aureus disease requires a seemingly high infectious dose and how interventions such as a vaccine may be more rationally developed

The Size, Shape, Albedo, Density, and Atmospheric Limit of Transneptunian Object (50000) Quaoar from Multi-chord Stellar Occultations

We present results derived from the first multi-chord stellar occultations by the transneptunian object (50000) Quaoar, observed on 2011 May 4 and 2012 February 17, and from a single-chord occultation observed on 2012 October 15. If the timing of the five chords obtained in 2011 were correct, then Quaoar would possess topographic features (crater or mountain) that would be too large for a body of this mass. An alternative model consists in applying time shifts to some chords to account for possible timing errors. Satisfactory elliptical fits to the chords are then possible, yielding an equivalent radius R [SUB]equiv[/SUB] = 555 ± 2.5 km and geometric visual albedo p[SUB]V[/SUB] = 0.109 ± 0.007. Assuming that Quaoar is a Maclaurin spheroid with an indeterminate polar aspect angle, we derive a true oblateness of \epsilon = 0.087^{+0.0268}_{-0.0175}, an equatorial radius of 569^{+24}_{-17} km, and a density of 1.99 ± 0.46 g cm[SUP]–3[/SUP]. The orientation of our preferred solution in the plane of the sky implies that Quaoar's satellite Weywot cannot have an equatorial orbit. Finally, we detect no global atmosphere around Quaoar, considering a pressure upper limit of about 20 nbar for a pure methane atmosphere.Peer reviewe

Rotación de cultivos en la producción de tabaco: Efecto sobre algunas propiedades edáficas

El cultivo de tabaco requiere numerosas labores, lo que sumado al escaso volumen de rastrojos que deja este cultivo, se favorece el deterioro físico, químico y biológico del suelo. El objetivo fue evaluar en un suelo del Valle los Pericos (Provincia de Jujuy), el efecto que ejercen sobre la calidad edáfica diferentes prácticas de manejo realizadas en el cultivo de tabaco: monocultivo (TM), rotación con gramíneas (TG) e incorporación de abonos verdes (TV), contrastando a su vez los resultados con los de una situación con bajo disturbio (T). Se estudió la respuesta de distintas variables edáficas determinadas a dos profundidades (0-20 cm y 20-40 cm), en lotes de producción de tabaco con diferentes rotaciones y más de 30 años bajo labranza convencional y riego. La agricultura provocó una merma del 44 % y 57 % en la estabilidad estructural promedio de los estratos superficial y profundo, respectivamente. La tasa de infiltración fue cinco veces superior en T. En los lotes agrícolas se observó un descenso marcado en todas las fracciones del carbono y entre un 8 % y 11% en el pH. La producción de tabaco bajo riego y fertilización mostró un aumento del 67 % al 100 % en la conductividad eléctrica del suelo y de más del 300 % en el fósforo extractable. La diversificación de cultivos generó en superficie, incrementos significativos del 54 % y 41 % del carbono orgánico total y asociado a la fracción mineral, respectivamente, mientras que el carbono particulado no varió según las distintas rotaciones agrícolas. El carbono de la biomasa microbiana superficial y profunda fue un 118 % y 159 % superior, respectivamente, en TG en relación al promedio de TV y TM, mientras que la respiración basal superficial fue un 83 % mayor en TG y TV respecto a TM.Tobacco cultivation requires numerous agricultural practices, which along with the low volume of stubble that it leaves, it favors soil physical, chemical and biological deterioration. The aim of this work was to evaluate, in a soil of Valle los Pericos (Jujuy Province), the effect on edaphic quality of crop rotations carried out in the tobacco cultivation: monoculture (TM), rotation with grasses (TG), incorporation of green manures (TV), and also compared these results with those of a low soil disturbance situation (T). The response of different edaphic variables was studied at two soil depths (0-20 cm and 20-40 cm), in tobacco production plots with different rotations and more than 30 years under conventional tillage and irrigation. Agriculture caused a decrease of 44 % and 57 % in the average structural stability at the superficial and deep layer, respectively. Infiltration rate was five times higher in T. A decrease in all carbon fractions and between 8 % and 11 % of soil pH was observed in cultivated plots. Tobacco production under irrigation and fertilization showed an increase from 67 % to 100 % in soil electrical conductivity and more than 300 % in the extractable phosphorus. Crop diversification generated in superficial layer significant increases of 54 % and 41 % of total and mineral associated organic carbon content, respectively, while particulate carbon did not change according to the different agricultural rotations. The superficial and deep carbon of the microbial biomass was 118 % and 159 % higher, respectively, in TG in relation to the TV and TM average, while superficial basal respiration was 83 % higher in TG and TV with respect to TM.Fil: Colque, Raúl A. Universidad Nacional de Jujuy. Facultad de Ciencias Agrarias; ArgentinaFil: Romaniuk, Romina Ingrid. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Suelos; ArgentinaFil: Arias, Patricia. Universidad Nacional de Jujuy. Facultad de Ciencias Agrarias; ArgentinaFil: Castiglioni, Mario Guillermo. Universidad de Buenos Aires. Facultad de Agronomía. Cátedra de Conservación y Manejo de Suelos; Argentin

Clinico-pathological findings in natural cases of "mascadera" in goats

"Mascadera" is a chronic emaciating neuropathy affecting goats; it produces significant economic losses in many regions and its cause is unknown. Here, the histological lesions found in 15 animals naturally affected by the disease are described. Complete necropsy was performed and tissue samples were collected for histopathological study. Severe atrophy of the masseter and buccinator muscles and tongue was observed, as well as vacuolar degeneration of neurons in the nuclei of the trigeminal, facial, and glossopharyngeal nerves. No relevant lesions were observed in other tissues. These findings and the clinical signs are consistent with those observed by other authors in animals spontaneously and experimentally intoxicated with Prosopis juliflora. The disease may be due to consumption of a similar species present in our country that is still unknown. Further research on the etiology and pathogenesis of this disease is needed to establish appropriate prevention guidelines.Facultad de Ciencias Veterinaria

Senna occidentalis poisoning in cattle: report of 8 outbreaks in northwestern Argentina

Senna occidentalis es una de las muchas especies de Senna presentes en Argentina, conocida por su toxicidad para los músculos cardíacos y las grandes masas musculares. Sin embargo, existen pocos informes sobre la intoxicación por S. occidentalis en bovinos en Argentina. Este trabajo tiene como objetivo describir un estudio retrospectivo que incluye brotes de intoxicación por S. occidentalis en bovinos del noroeste argentino. También se detallaron los aspectos clínicos, patológicos y epidemiológicos de cada brote. Los animales afectados mostraron debilidad, incoordinación y mioclonías de las grandes masas musculares. Algunos también mostraron signos clínicos inespecíficos como depresión, anorexia, pérdida de peso y decúbito antes de morir. El principal hallazgo macroscópico fue una necrosis muscular en las grandes masas musculares, y los hallazgos histológicos incluyeron degeneración segmentaria multifocal y necrosis de las fibras musculares. Las muestras de suero recolectadas de los animales a los que se les realizó necropsia mostraron niveles altos de CPK en los casos más agudos.Senna occidentalis is one of the many Senna species present in Argentina known for its toxicity to cardiac muscles and large muscle masses. However, there are only a few reports about S. occidentalis poisoning in cattle to date in Argentina. This work aims to describe a retrospective study, which includes 8 outbreaks of S. occidentalis poisoning in cattle from northwestern Argentina. The clinical, pathological, and epidemiological aspects of each outbreak were also detailed. The affected animals showed weakness, incoordination, and myoclonus of large muscle masses.Some animals also showed non-specific clinical signs like depression, anorexia, weight loss, and recumbency before death. The main macroscopic finding was muscle necrosis in large muscle masses and the histological findings included multifocal segmental degeneration and necrosis of muscle fibers. Serum samples collected from the necropsied animals showed a high CPK activity in the most acute cases.Fil: Ovelar, María Florencia. Universidad Nacional del Nordeste. Facultad de Ciencias Veterinarias; ArgentinaFil: Medina Vallejo, Diego Martín Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Facultad de Ciencias Agrarias y Veterinarias ; Universidad Catolica de Salta; . Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Investigación Animal del Chaco Semiárido; ArgentinaFil: Colque Caro, Luis Adrián. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Investigación Animal del Chaco Semiárido; ArgentinaFil: Avellaneda Caceres, Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Investigación Animal del Chaco Semiárido; ArgentinaFil: Aguirre Castro, Laura Sabrina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Investigación Animal del Chaco Semiárido; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Sandoval, Gabriela Virginia. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Investigación Animal del Chaco Semiárido; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ruiz, A. F.. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Investigación Animal del Chaco Semiárido; Argentina. Universidad Nacional del Nordeste; ArgentinaFil: Micheloud, Juan Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Investigación Animal del Chaco Semiárido; Argentin

Relationship between endotoxin core, staphylococcal and varicella antibody levels and outcome following aortic valve replacement surgery: a prospective observational study

Background: Morbidity and mortality following cardiac valve surgery is high. Immunity is an important contributor to outcome. This study examines the relationship of staphylococcal and endotoxin antibody levels to outcome following cardiac surgery. Methods: Using enzyme-linked immunosorbent assays (ELISA), we measured pre-operative levels of antibodies to endotoxin core (EndoCAb); 3 common staphylococcal epitopes and varicella on saved serum of 60 adult patients scheduled to undergo elective primary surgical aortic valve replacement (AVR). Primary outcome measure was post-operative length of stay (LOS) in hospital with secondary outcomes being development of infective complications, length of stay on the intensive care unit (ICU) and 30-day mortality. Patients were quartiled according to antibody levels and outcomes compared between the quartile groups using Mann-Whitney tests for length of stay and Fisher's test for development of infection. Results: Sixty patients (34 M, 26 F) were recruited with mean age 73 years (IQR 66-78), mean body mass index (BMI) 27.7 (IQR 25-31) and EuroSCORE II 1.44 (0.95-1.99). Those patients in the lower quartile for pre-operative antibody level had a longer post-operative stay than the upper quartile. EndoCAb (median IgG level Q1 42.2 MU/ml vs Q4 256 MU/ml) 9 vs 6 days, p = 0.025; alpha-toxin (median IgG level Q1 63 U vs Q4 558 U) 10 vs 7 days, p = 0.034; teichoic acid (median IgG level Q1 14 U vs Q4 419 U) 10 vs 8 days, p = 0.441; staphylococcal enterotoxin A (median IgG level Q1 55 U vs Q4 427 U) 9 vs 7 days, p = 0.865; varicella zoster (median IgG level Q1 1.325 U vs Q4 2.54 U) 8 vs 7 days, p = 1.0; and combined antibody levels 10 vs 6 days, p = 0.017. There were no differences in the number developing post-operative infections for each antibody type. The combined antibody analysis suggested a reduction in proportion of individuals developing infection from the upper vs lower quartile: 0 vs 0.33, p = 0.042. Conclusions: This study again suggests the inverse relationship between endotoxin core antibody levels and outcome following aortic valve surgery as well as suggesting a similar relationship with antibodies to staphylococcus. There is no such relationship for antibody levels against an organism not providing a peri-operative threat. Understanding this relationship may enable therapeutic manipulation of immune status, re-evaluation of risk and further investigation of the low immune state. Trial registration: The patients in this study are a sub-group of the RELIEF AS study