•Six supercoolers with icephobic coatings were tested for ice slurry generators.•Three different chemical families were assessed at different mass flow rates.•Coated supercoolers achieve average ...supercooling degrees in the range of 3 K to 4 K.•Best icephobic coatings increase the supercooling degree by 30 % to 40 %.
A supercooler is a heat exchanger that allows to supercool water avoiding ice nucleation on the heat exchanger surface. In this paper, six supercoolers with icephobic coatings were tested for supercooling ice slurry generators. As reference, a supercooler without any coating was used. For coating comparison, three different chemical families were tested at different mass flow rates. Experiments of coated heat exchangers show average supercooling degrees in the range of 3K to 4K. All icephobic coatings improved the supercooling degree respect to the reference non coated case by 7% to 44% at 1000kgh−1 mass flow rate with supercooling powers up to 5 kW. For a mass flow rate of 2000kgh−1 a supercooling power of about 6kW has been reached for five coatings at a temperature of −2.5∘C and hold constant for a time span of 3h. Some coatings could reach lower temperatures at this mass flow, but the experimental setup was limited to this supercooling power. The two coatings performing best in the heat exchanger tests were both from the family class hybrid organic-inorganic silane sol-gel with improvements in the degree of supercooling respect to the reference uncoated heat exchanger of 30% to 40%. The supercooling degrees achieved in the present work are up to two times larger compared to results published in scientific journals until this date using industrially relevant heat exchangers.
Direct measurements of stellar magnetic fields are based on the splitting of spectral lines into polarized Zeeman components. With a few exceptions, Zeeman signatures are hidden in data noise, and a ...number of methods have been developed to measure the average, over the visible stellar disk, of longitudinal components of the magnetic field. At present, faint stars are only observable via low-resolution spectropolarimetry, which is a method based on the regression of the Stokes V signal against the first derivative of Stokes I. Here, we present an extension of this method to obtain a direct measurement of the transverse component of stellar magnetic fields by the regression of high-resolution Stokes Q and U as a function of the second derivative of Stokes I. We also show that it is possible to determine the orientation in the sky of the rotation axis of a star on the basis of the periodic variability of the transverse component due to its rotation. The method is applied to data, obtained with the Catania Astrophysical Observatory Spectropolarimeter along the rotational period of the well known magnetic star β CrB.
As well known, micro and nanosatellites are being proposed for a variety of space missions, due to the advantages offered in terms of flexibility, cost and development time-scales. They also allow ...the development of space missions based on distributed architectures, composed of a number of small platforms in coordinated flight. However, technological advancements are still needed to make micro and nanosatellite competitive with respect to larger platforms. In this paper, we explore the potentiality offered by hyper hemispheric lens for the development of miniaturized and multi-function sensors for use on board of micro satellites. Hyper hemispheric lens belong to the ultra-wide field-of-view optical objectives. Here a novel optics of this category is presented. Its field of view is 360° in azimuth (panoramic capabilities) and 135° for the off-boresight angle (hyper-hemispheric field). With such capabilities the lens may be exploited as a very-large field-of-view optics where moving parts can be avoided. This is of interest to space applications, in which devices with any moving part, representing a possible point of failure, shall be avoided or reduced to the minimum. A hyper hemispheric lens may, then, be adopted for electro optical devices in space satellite subsystems, such as star-, Sun- and Earth-sensors, or for monitoring the environment surrounding the satellite in the case of on-orbit servicing or active debris removal operations. Weight and cost budgets for small and micro satellites are also important parameters to determine their success. Hyper hemispheric lens may be kept quite compact in dimension and the need of a single imaging detector, for a so large field of view, strongly reduces costs. In this paper, we explore possible applications of a multi-purpose space device based on a hyper hemispheric lens on board of micro and nanosatellites.
To identify the major determinants of survival and nonsurvival for patients in need of intra-aortic balloon pump (IABP) support after cardiac surgery and to define the role of ventilator-associated ...pneumonia.
Retrospective study.
University and general hospital.
A total of 105 consecutive patients undergoing cardiac surgery requiring IABP support and prolonged mechanical ventilation for >24 hours.
All patients were assigned into 1 of 2 groups: survival (n = 69) and nonsurvival (n = 36).
Differences between the survival and nonsurvival groups were tested with the Student's t-test, chi-square test, and frequency analysis. The overall survival rate was 65.7%. Nonsurvivors (34.3%) had higher rates of acute myocardial infarction (27.7% v 4.3%; p < 0.002), Canadian Cardiovascular Society functional class III and IV (44.4% and 13.8%; p < 0.001), and depressed left ventricular ejection fraction (31.3 +/- 6.4% v 42.4 +/- 7.2%; p < 0.001). The nonsurvival group had longer duration of cardiopulmonary bypass (165 +/- 74.3 minutes v 135 +/- 36 minutes; p < 0.006) and aortic occlusion (81.8 +/- 9 minutes v 68.6 +/- 25.7 minutes; p < 0.004). In the nonsurvival group, 21 patients were not weaned from the IABP, and 15 patients were weaned from the IABP but died from renal failure (26.6%), multiorgan failure (13.3%), infection, and respiratory failure (66.6%). In the nonsurvival group, mechanical ventilation time was longer in patients weaned from the IABP.
These data suggest that for patients not weaned from the IABP, the major determinants of death are low cardiac output (33.3%) and multiorgan failure (47.6%). Patients with a left ventricular ejection fraction of <30% have a poorer outcome. In patients weaned from the IABP, ventilator-associated pneumonia (66.6%) was the major cause of death.
PLATO stands for PLAnetary Transits and Oscillations and it is the forthcoming third Medium sized mission of ESA, planned to be launched in 2024. Its optical payload is an ensemble of 34 small ...telescopes that mimic a single one meter class aperture with a huge Field of View of more than 50° in size. Aiming to find exoplanets around bright nearby stars it is designed to discover a significant number of relatively nearby Earth-like worlds. A description of the optomechanical adopted solution and a speculative scenario to further explore such alien worlds is briefly given.
We present development progress of the scheduler for the Son Of X-Shooter (SOXS) instrument at the ESO-NTT 3.58 meter telescope. SOXS will be a single object spectroscopic facility, consisting of a ...two-arms high-efficiency spectrograph covering the spectral range 350-2000 nanometer with a mean resolving power R\(\approx\)4500. SOXS will be uniquely dedicated to the UV-visible and near infrared follow up of astrophysical transients, with a very wide pool of targets available from the streaming services of wide-field telescopes, current and future. This instrument will serve a variety of scientific scopes in the astrophysical community, with each scope eliciting its specific requirements for observation planning, that the observing scheduler has to meet. Due to directions from the European Southern Observatory (ESO), the instrument will be operated only by La Silla staff, with no astronomer present on the mountain. This implies a new challenge for the scheduling process, requiring a fully automated algorithm that should be able to present the operator not only with and ordered list of optimal targets, but also with optimal back-ups, should anything in the observing conditions change. This imposes a fast-response capability to the scheduler, without compromising the optimization process, that ensures good quality of the observations. In this paper we present the current state of the scheduler, that is now almost complete, and of its web interface.
In this paper, we consider the recently proposed family of continual learning models, called Gated Linear Networks (GLNs), and study two crucial aspects impacting on the amount of catastrophic ...forgetting affecting gated linear networks, namely, data standardization and gating mechanism. Data standardization is particularly challenging in the online/continual learning setting because data from future tasks is not available beforehand. The results obtained using an online standardization method show a considerably higher amount of forgetting compared to an offline -static- standardization. Interestingly, with the latter standardization, we observe that GLNs show almost no forgetting on the considered benchmark datasets. Secondly, for an effective GLNs, it is essential to tailor the hyperparameters of the gating mechanism to the data distribution. In this paper, we propose a gating strategy based on a set of prototypes and the resulting Voronoi tessellation. The experimental assessment shows that the proposed approach is more robust to different data standardizations compared to the original one, based on a halfspace gating mechanism, and shows improved predictive performance.
The Son Of X-Shooter (SOXS) is a single object spectrograph, built by an international consortium for the 3.58-m ESO New Technology Telescope at the La Silla Observatory 1. It offers a simultaneous ...spectral coverage over 350-2000 nm, with two separate spectrographs. In this paper we present the status of the Near InfraRed (NIR) cryogenic echelle cross-dispersed spectrograph 1, in the range 0.80-2.00 {\mu}m with 15 orders, equipped with an 2k x 2k Hawaii H2RG IR array from Teledyne, working at 40K, that is currently assembled and tested on the SOXS instrument, in the premises of INAF in Padova. We describe the different tests and results of the cryo, vacuum, opto-mechanics and detector subsystems that finally will be part of the PAE by ESO.
We present the advancements in the development of the scheduler for the Son Of X-shooter instrument at the ESO-NTT 3.58-m telescope in La Silla, Chile. SOXS is designed as a single-object ...spectroscopic facility and features a high-efficiency spectrograph with two arms covering the spectral range of 350-2000 nm and a mean resolving power of approximately R=4500. It will conduct UV-visible and near-infrared follow-up observations of astrophysical transients, drawing from a broad pool of targets accessible through the streaming services of wide-field telescopes, both current and future, as well as high-energy satellites. The instrument will cater to various scientific objectives within the astrophysical community, each entailing specific requirements for observation planning. SOXS will operate at the European Southern Observatory (ESO) in La Silla, without the presence of astronomers on the mountain. This poses a unique challenge for the scheduling process, demanding a fully automated algorithm that is autonomously interacting with the appropriate databases and the La Silla Weather API, and is capable of presenting the operator not only with an ordered list of optimal targets (in terms of observing constraints) but also with optimal backups in the event of changing weather conditions. This imposes the necessity for a scheduler with rapid-response capabilities without compromising the optimization process, ensuring the high quality of observations and best use of the time at the telescope. We thus developed a new highly available and scalable architecture, implementing API Restful applications like Docker Containers, API Gateway, and Python-based Flask frameworks. We provide an overview of the current state of the scheduler, which is now ready for the approaching on-site testing during Commissioning phase, along with insights into its web interface and preliminary performance tests.
SOXS (Son Of X-Shooter) is the new single object spectrograph for the ESO New Technology Telescope (NTT) at the La Silla Observatory, able to cover simultaneously both the UV-VIS and NIR bands ...(350-2000 nm). The instrument is currently in the integration and test phase, approaching the Preliminary Acceptance in Europe (PAE) before shipment to Chile for commissioning. After the assembly and preliminary test of the control electronics at INAF - Astronomical Observatory of Capodimonte (Napoli), the two main control cabinets of SOXS are now hosted in Padova, connected to the real hardware. This contribution describes the final electronic cabinets layout, the control strategy and the different integration phases, waiting for the Preliminary Acceptance in Europe and the installation of the instrument in Chile.
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