Interlayer potassium and its neighboring atoms in micas : Crystal-chemical modeling and XANES spectroscopy

A detailed description of the interlayer site in trioctahedral true micas is presented based on a statistical appraisal of crystal-chemical, structural, and spectroscopic data determined on two sets of trioctahedral micas extensively studied by both X-ray diffraction refinement on single crystals (SC-XRD) and X-ray absorption fine spectroscopy (XAFS) at the potassium K -edge. Spectroscopy was carried out on both random powders and oriented cleavage flakes, the latter setting taking advantage of the polarized character of synchrotron radiation. Such an approach (AXANES) is shown to be complementary to crystal-chemical investigation based on SC-XRD refinement. However, the results are not definitive as they focus on few samples having extreme features only (e.g., end-members, unusual compositions, and samples with extreme and well-identified substitution mechanisms). The experimental absorption K -edge (XANES) for potassium was decomposed by calculation and extrapolated into a full in-plane absorption component (σ||) and a full out-of-plane absorption component (σ⊥). These two patterns reflect different structural features: σ|| represents the arrangement of the atoms located in the mica interlayer space and facing tetrahedral sheets; σ⊥ is associated with multiple-scattering interactions entering deep into the mica structure, thus also reflecting interactions with the heavy atoms (essentially Fe) located in the octahedral sheet. The out-of-plane patterns also provide insights into the electronic properties of the octahedral cations, such as their oxidation states (e.g., Fe2+ and Fe3+) and their ordering (e.g., trans - vs. cis -setting). It is also possible to distinguish between F- and OH-rich micas due to peculiar absorption features originating from the F vs. OH occupancy of the O4 octahedral site. Thus, combining crystal-chemical, structural, and spectroscopic information is shown to be a practical method that allows, on one hand, assignment of the observed spectroscopic features to precise structural pathways followed by the photoelectron within the mica structure and, on the other hand, clarification of the amount of electronic interactions and forces acting onto the individual atoms at the various structural sites

Employment of factorial design for optimization of pirolisys and atomization temperatures for Al, Cd, Mo and Pb determination by ETAAS

This work describes a factorial design for the optimization of pyrolysis and atomization temperatures in ETAAS. As examples, Cd and Pb were determined using lower pyrolysis and atomization temperatures and Al and Mo with higher pyrolysis and atomization temperatures. Good results were obtained for Cd employing Rh (m o = 1.4 pg) as a permanent modifier with pyrolysis and atomization temperatures of 640 and 1500 °C, respectively. For Zr, W or Zr+W, the Cd pyrolysis and atomization temperatures were 500 and 1500 °C, respectively, with m o = 1.4 pg using Zr or W and 1.5 pg using Zr+W. The best results for Pb were those using Rh, Zr, W and Zr+Rh, obtaining characteristic masses of 42, 37, 34 and 36 pg, respectively. Pyrolysis and atomization temperatures of 910 and 1850 °C, respectively, were achieved for this metal. For Al, the best results were obtained when Zr or Zr+W were used. Mo was also tested as a possible permanent modifier for Al, but the results were not satisfactory. The results obtained for Mo without modifier were similar to those with conventional modifiers (Mg or Pd+Mg) and the results obtained using permanent chemical modifiers were not satisfactory. In all situations, the experiments were performed faster than those using the univariate procedure.246253Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Status report of the SRT radiotelescope control software: the DISCOS project

The Sardinia Radio Telescope (SRT) is a 64-m fully-steerable radio telescope. It is provided with an active surface to correct for gravitational deformations, allowing observations from 300 MHz to 100 GHz. At present, three receivers are available: a coaxial LP-band receiver (305-410 MHz and 1.5-1.8 GHz), a C-band receiver (5.7-7.7 GHz) and a 7-feed K-band receiver (18-26.5 GHz). Several back-ends are also available in order to perform the different data acquisition and analysis procedures requested by scientific projects. The design and development of the SRT control software started in 2004, and now belongs to a wider project called DISCOS (Development of the Italian Single-dish COntrol System), which provides a common infrastructure to the three Italian radio telescopes (Medicina, Noto and SRT dishes). DISCOS is based on the Alma Common Software (ACS) framework, and currently consists of more than 500k lines of code. It is organized in a common core and three specific product lines, one for each telescope. Recent developments, carried out after the conclusion of the technical commissioning of the instrument (October 2013), consisted in the addition of several new features in many parts of the observing pipeline, spanning from the motion control to the digital back-ends for data acquisition and data formatting; we brie y describe such improvements. More importantly, in the last two years we have supported the astronomical validation of the SRT radio telescope, leading to the opening of the first public call for proposals in late 2015. During this period, while assisting both the engineering and the scientific staff, we massively employed the control software and were able to test all of its features: in this process we received our first feedback from the users and we could verify how the system performed in a real-life scenario, drawing the first conclusions about the overall system stability and performance. We examine how the system behaves in terms of network load and system load, how it reacts to failures and errors, and what components and services seem to be the most critical parts of our architecture, showing how the ACS framework impacts on these aspects. Moreover, the exposure to public utilization has highlighted the major flaws in our development and software management process, which had to be tuned and improved in order to achieve faster release cycles in response to user feedback, and safer deploy operations. In this regard we show how the introduction of testing practices, along with continuous integration, helped us to meet higher quality standards. Having identified the most critical aspects of our software, we conclude showing our intentions for the future development of DISCOS, both in terms of software features and software infrastructures. <P /

Dish Washer: a Software Tool for RFI Mitigation in Single-dish Radio Astronomical Observations

Radio Frequency Interference is one of the most pressing problems in cm-wavelength world-wide radio astronomy, in particular for single-dish telescope observations. Due to both the increasing abundance of man-made interfering signals and the improved performance of the telescope instrumentation, the impact of RFI at the Italian radio telescope sites is now a major concern, thus strategies for its mitigation are to be applied. Dish Washer is a new software tool for the detection and flagging of RFI in signals collected by single-dish radio telescopes. It implements both interactive flagging and some level of automatic detection of RFI through dedicated algorithms. Its first public release is foreseen as free software under the GNU General Public License

Towards coordinated site monitoring and common strategies for mitigation of Radio Frequency Interference at the Italian radio telescopes

We present a project to implement a national common strategy for the mitigation of the steadily deteriorating Radio Frequency Interference (RFI) situation at the Italian radio telescopes. The project involves the Medicina, Noto, and Sardinia dish antennas and comprised the definition of a coordinated plan for site monitoring as well as the implementation of state-of-the-art hardware and software tools for RFI mitigation. Coordinated monitoring of frequency bands up to 40 GHz has been performed by means of continuous observations and dedicated measurement campaigns with fixed stations and mobile laboratories. Measurements were executed on the frequency bands allocated to the radio astronomy and space research service for shared or exclusive use and on the wider ones employed by the current and under-development receivers at the telescopes. Results of the monitoring campaigns provide a reference scenario useful to evaluate the evolution of the interference situation at the telescopes sites and a case series to test and improve the hardware and software tools we conceived to counteract radio frequency interference. We developed a multi-purpose digital backend for high spectral and time resolution observations over large bandwidths. Observational results demonstrate that the spectrometer robustness and sensitivity enable the efficient detection and analysis of interfering signals in radio astronomical data. A prototype off-line software tool for interference detection and flagging has been also implemented. This package is capable to handle the huge amount of data delivered by the most modern instrumentation on board of the Italian radio telecsopes, like dense focal plane arrays, and its modularity easen the integration of new algorithms and the re-usability in different contexts or telescopes.Comment: 39 pages, 10 Figures and 7 Tables. INAF Technical Report n. 149 (2022). http://hdl.handle.net/20.500.12386/3208

Starlight. La nascita dell'astrofisica in Italia / The origins of astrophysics in Italy

Starlight è una mostra a rete, con cinque sezioni dislocate in cinque osservatori diversi, raccordati virtualmente tramite l'omonima mostra virtuale bilingue. E' stata il prodotto finale del progetto "Analyzing starlight", finanziato da INAF con PDIN 2014, che include anche il catalogo cartaceo e la versione online della mostra. Le cinque sezioni sono così costituite: 1. Le origini dell'astrofisica a Firenze (sede: INAF-Osservatorio Astrofisico di Arcetri, Firenze); 2. Roma, capitale dell'astrofisica (sede: INAF-Osservatorio Astronomico di Roma, Monte Porzio Catone); 3. L'eclisse totale di sole del 1870 (sede: INAF-Osservatorio Astronomico di Capodimonte, Napoli); 4. Lo sviluppo della fisica solare (sede: Chiesa di S. Maria delle Grazie, Palazzo dei Normanni, Palermo); 5. Una società scientifica italiana per l'astrofisica (sede: INAF-Osservatorio Astronomico di Padova

Be social, be agile: team engagement with Redmine

System engineering and project-team management are essential tools to ensure the project success and the Redmine is a valuable platform for the work organization and for a system engineered approach. We review in this work the management needs related to our project, and suggest the possibility that they fit to many research activities with a similar scenario: small team, technical difficulties (or unknowns), intense activity sprints and long pauses due to external schedule management, a large degree of shared leadership. We will then present our implementation with the Redmine, showing that the use of the platform resulted in a strong engagement and commitment of the team. The explicit goal of this work is also to rise, at least internally, the awareness about team needs and available organizational tools and methods; and to highlight a shareable approach to team management and small scale system engineering

Performance of Braford steers grazing on cultivated pastures and fed or not fed an energy supplement

This experiment evaluated the performance of 84 Braford steers grazing on summer and winter cultivated pastures fed or not fed an energy-protein supplement. Steers were 10 months old and weighed, on average, 165 kg at the beginning of the trial. Steers grazed on cultivated winter pasture, consisting of black oats (Avena strigosa) and ryegrass (Lolium multiflorum Lam.), and then on cultivated summer pasture, consisting of Napier grass (Pennisetum purpureum). The following treatments were applied: SS - supplement was fed during both seasons; SN - supplement was fed only during the winter; NS - supplement was fed only during the summer; and NN - steers were not fed any supplement. Supplementation resulted in higher body weight and better body condition score (SS: 369.2 and 4.52; SN: 335.2 and 4.01; NS: 352.5 and 4.49; SS: 322.5 and 3.83). Longissimus dorsi area was larger in supplemented steers, which also presented thicker backfat when compared with those not fed any supplement (3.67 and 2.29 mm, respectively)

The Sardinia Radio Telescope . From a technological project to a radio observatory

Context. The Sardinia Radio Telescope (SRT) is the new 64 m dish operated by the Italian National Institute for Astrophysics (INAF). Its active surface, comprised of 1008 separate aluminium panels supported by electromechanical actuators, will allow us to observe at frequencies of up to 116 GHz. At the moment, three receivers, one per focal position, have been installed and tested: a 7-beam K-band receiver, a mono-feed C-band receiver, and a coaxial dual-feed L/P band receiver. The SRT was officially opened in September 2013, upon completion of its technical commissioning phase. In this paper, we provide an overview of the main science drivers for the SRT, describe the main outcomes from the scientific commissioning of the telescope, and discuss a set of observations demonstrating the scientific capabilities of the SRT. Aims: The scientific commissioning phase, carried out in the 2012-2015 period, proceeded in stages following the implementation and/or fine-tuning of advanced subsystems such as the active surface, the derotator, new releases of the acquisition software, etc. One of the main objectives of scientific commissioning was the identification of deficiencies in the instrumentation and/or in the telescope subsystems for further optimization. As a result, the overall telescope performance has been significantly improved. Methods: As part of the scientific commissioning activities, different observing modes were tested and validated, and the first astronomical observations were carried out to demonstrate the science capabilities of the SRT. In addition, we developed astronomer-oriented software tools to support future observers on site. In the following, we refer to the overall scientific commissioning and software development activities as astronomical validation. Results: The astronomical validation activities were prioritized based on technical readiness and scientific impact. The highest priority was to make the SRT available for joint observations as part of European networks. As a result, the SRT started to participate (in shared-risk mode) in European VLBI Network (EVN) and Large European Array for Pulsars (LEAP) observing sessions in early 2014. The validation of single-dish operations for the suite of SRT first light receivers and backends continued in the following year, and was concluded with the first call for shared-risk early-science observations issued at the end of 2015. As discussed in the paper, the SRT capabilities were tested (and optimized when possible) for several different observing modes: imaging, spectroscopy, pulsar timing, and transients