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We characterize the daytime sky quality in terms of brightness, cloud coverage, and mainweather variables at the Carlos Ulrico Cesco station of the Felix Aguilar Astronomical Ob-servatory (OAFA), located in El Leoncito National Park, San Juan, Argentina. We have col-lected more than 15 years of daily observations from the auxiliary sky brightness detectorsof the Mirror Coronagraph for Argentina (MICA, in operations from 1997 to 2012), includ-ing daily observing reports. We additionally present data from two meteorological stationsoperated at the site from 2000 to 2020. We determine the main statistical properties andseasonal variability of daytime sky brightness, clear sky time fraction (CSTF), precipitablewater vapor (WV), temperature, humidity, and wind speed, which are relevant for solar,particularly coronal observations.Our results confirm that El Leoncito is an excellent place to perform daytime astro-nomical observations. We measure a median sky brightness of 15.8 ppm, estimated at526.0±1.0 nm and 6 solar radii from the solar disk center; a median CSTF of 0.7; anda median WV below 6 mm. These values, and those of other relevant weather variables, arecomparable to the levels found among the best astronomical observing sites in the world.Due to the extended period of time analyzed and high sampling frequency, the novel dataand results presented in this report contribute to the analysis and interpretation of historicalsky brightness data and are of great value for the future planning of daytime astronomicalinstrumentation at El Leoncito.

Motivated by improving predictions of arrival times at Earth of shocks driven by coronal mass ejections (CMEs), we have analyzed 71 Earth-directed events in different stages of their propagation. The study is primarily based on approximated locations of interplanetary (IP) shocks derived from Type-II radio emissions detected by the Wind /WAVES experiment during 1997 – 2007. Distance–time diagrams resulting from the combination of white-light corona, IP Type-II radio, and in-situ data lead to the formulation of descriptive profiles of each CME’s journey toward Earth. Furthermore, two different methods for tracking and predicting the location of CME-driven IP shocks are presented. The linear method, solely based on Wind /WAVES data, arises after key modifications to a pre-existing technique that linearly projects the drifting low-frequency Type-II emissions to 1 AU. This upgraded method improves forecasts of shock-arrival times by almost 50 %. The second predictive method is proposed on the basis of information derived from the descriptive profiles and relies on a single CME height–time point and on low-frequency Type-II radio emissions to obtain an approximate value of the shock arrival time at Earth. In addition, we discuss results on CME–radio emission associations, characteristics of IP propagation, and the relative success of the forecasting methods.

The properties of ceramic materials are intimately related to a variety of factors, among them shaping procedure and sintering time. These factors condition, the microstructure and properties of the materials developed. Our study has formed materials from clays commonly used in the area of Bailén (Jaén) and wet pomace proceeding from the extraction of olive oil. The materials were shaped through extrusion. In this study, raw materials have been characterized and studied interesting properties of sintered materials, such as compressive strength, water absorption, open porosity or bulk density. The study concluded that the addition of wet pomace from olive oil industry into traditional brick entails a saving of raw materials and reducing the environmental impact generated by their manufacture. The best results are obtained for the samples with waste content of 3 wt %.

Sunrise is a 1-m optical solar observatory carried aloft by a stratospheric balloon. It was developed to study magnetic fields and plasma flows in the solar atmosphere with very high spatial resolution and sensitivity. The Sunrise UV Spectropolarimeter and Imager (SUSI) operates in the 309 – 417 nm range, covering thousands of spectral lines that are poorly accessible from the ground and largely unexplored. The instrument includes a dual-beam polarimeter based on a rotating waveplate, a polarization beam splitter and two custom-made CMOS cameras. SUSI gathers data at high spectral, spatial and temporal resolution. These data are stored onboard during flight. Given that SUSI does not include a polarimetric calibration unit onboard, its polarimetric demodulation matrix is estimated during laboratory calibration measurements prior to its flight. The quality of this calibration is crucial to accurately demodulate the data post-flight and reach the instrument’s maximum polarimetric sensitivity goal of 1 × 10 − 3 of the continuum intensity. In this paper, we report the results of eighth polarimetric calibrations of SUSI standalone, acquired at six different wavelengths using artificial LED light sources. The field-dependant demodulation matrices obtained are within the values expected from the design, including their polarimetric efficiencies and temporal stability. The matrices are also confirmed to satisfy the calibration repeatability criterion imposed by the SUSI sensitivity goal.

Deciphering the physical properties of flares is crucial for understanding the nature of one of the most energetic events on the Sun. We analyze high spatial and spectral resolution observations of a C-class flare, focusing on a complex light bridge in the active region. The observations show Stokes profiles with opposite Doppler shifts and asymmetries between photospheric and chromospheric spectral lines, and Ca ii infrared spectral lines in emission, tracing areas of extreme atmospheric heating. Inversion results are consistent with these spectral features, showing regions of opposite-sign plasma flows between the photosphere and chromosphere, adjacent to areas with extreme chromospheric temperatures. The latter areas show relatively weak line-of-sight velocities despite the intense heating. The magnetic field configuration shows abrupt changes with height in the regions with opposite-sign flows, while remaining nearly constant with height in the areas of extreme heating. These findings point to a scenario of small-scale magnetic reconnection in the photosphere, suggesting a flare triggering mechanism based on an avalanche of many small reconnection events.

In this paper, the authors have studied the effects of the different sintering atmospheres (vacuum, nitrogen-hydrogen, and dissociate ammonia) on 50A-50F duplex stainless steels, fabricated by the powder metallurgy process. The DSS sintered in atmosphere of N 2 -H 2 exhibit a tensile strength of at least 500 MPa with an elongation to fracture smaller than 2%. The presence of nitrides was the main cause of the deterioration in the corrosion resistance.

Posttranscriptional gene silencing (PTGS) in transgenic plants is an epigenetic form of RNA degradation related to PTGS and RNA interference (RNAi) in fungi and animals. Evidence suggests that transgene loci and RNA viruses can generate double-stranded RNAs similar in sequence to the transcribed region of target genes, which then undergo endonucleolytic cleavage to generate small interfering RNAs (siRNA) that promote degradation of cognate RNAs. The silent state in transgenic plants and in Caenorhabditis elegans can spread systemically, implying that mobile silencing signals exist. Neither the chemical nature of these signals nor their exact source in the PTGS pathway is known. Here, we use a positive marker system and real-time monitoring of green fluorescent protein expression to show that large sense, antisense, and double-stranded RNAs as well as double-stranded siRNAs delivered biolistically into plant cells trigger silencing capable of spreading locally and systemically. Systemically silenced leaves show greatly reduced levels of target RNA and accumulate siRNAs, confirming that RNA can induce systemic PTGS. The induced siRNAs represent parts of the target RNA that are outside of the region of homology with the triggering siRNA. Our results imply that siRNAs themselves or intermediates induced by siRNAs could comprise silencing signals and that these signals induce self-amplifying production of siRNAs.

We present a decision theoretic formulation of product partition models (PPMs) that allows a formal treatment of different decision problems such as estimation or hypothesis testing and clustering methods simultaneously. A key observation in our construction is the fact that PPMs can be formulated in the context of model selection. The underlying partition structure in these models is closely related to that arising in connection with Dirichlet processes. This allows a straightforward adaptation of some computational strategies-originally devised for nonparametric Bayesian problems-to our framework. The resulting algorithms are more flexible than other competing alternatives that are used for problems involving PPMs. We propose an algorithm that yields Bayes estimates of the quantities of interest and the groups of experimental units. We explore the application of our methods to the detection of outliers in normal and Student t regression models, with clustering structure equivalent to that induced by a Dirichlet process prior. We also discuss the sensitivity of the results considering different prior distributions for the partitions.

Motivated by the need to improve the ability to forecast whether a certain coronal mass ejection (CME) is to impact Earth, and by the insufficiency of statistical studies that analyze the whole erupting system with the focus on the governing conditions under CME deflections, we performed a careful analysis of 13 events along a one-year time interval showing large deflections from their source region. We used telescopes imaging the solar corona at different heights and wavelengths on board the Project for Onboard Autonomy 2 (PROBA2), Solar Dynamics Observatory (SDO), Solar TErrestrial RElations Observatory (STEREO), Solar and Heliospheric Observatory (SOHO) spacecraft and from National Solar Observatory (NSO). By taking advantage of the quadrature position of these spacecraft from October 2010 until September 2011, we inspected the 3D trajectory of CMEs and their associated prominences with respect to their solar sources by means of a tie-pointing tool and a forward model. Considering the coronal magnetic fields as computed from a potential field source surface model, we investigate the roles of magnetic energy distribution and kinematic features in the non-radial propagation of both structures. The magnetic environment present during the eruption is found to be crucial in determining the trajectory of CMEs, in agreement with previous reports.

Fiber concretes have been revolutionizing the market, as well as lower operating costs, structurally act. The total or partial replacement of steel with natural fiber reinforced concrete could be an economical way to provide an alternative method to achieve greater security in concrete structures, as well as a way to use materials that are energy efficient, economic and ecological.Sisal fiber reinforcement is promising for use in composite materials, due to their low cost, low density, high strength and specific modulus, without risk to health, readily available in some countries and renewal.We studied four different dosages of concrete: without fiber, with two different types of polypropylene (PP) fibers and with sisal fiber. Consistency of fresh concrete, bulk density, water absorption, capillary absorption, compressive strength and microstructural properties values of the samples were investigated.Regarding the consistency of fresh concrete, measured by testing Abrams cone, as the results show a substantial difference between the flowability of the concrete without addition of fibers and other dosages with different types of fibers studied. The compressive strength test at 7 and 21 days also shows resistance as early ages performed fiber, while with increasing days of curing, the resistance becomes a reaction product of cement and pozzolanic water have no effect added fiber. Absorption tests and capillary absorption of water, like the above, consistent with the results shown bibliographic polled, the results being higher in both assays for dosages comprised of PP and sisal fibers.