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"Grassi, D"
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Io Hot Spot Distribution Detected by Juno/JIRAM
2023
In this work, we present the most updated catalog of Io hot spots based on Juno/JIRAM data. We find 242 hot spots, including 23 previously undetected. Over the half of the new hot spots identified, are located at high northern and southern latitudes (>70°). We observe a latitudinal variability and a larger concentration of hot spots in the polar regions, in particular in the North. The comparison between JIRAM and the most recent Io hot spot catalogs listing power output (Veeder et al., 2015, https://doi.org/10.1016/j.icarus.2014.07.028; de Kleer, de Pater, et al., 2019, https://doi.org/10.3847/1538-3881/ab2380), shows JIRAM detected 63% and 88% of the total number of hot spots, respectively. Furthermore, JIRAM observed 16 of the 34 faint hot spots previously identified. JIRAM data revealed thermal emission from 5 dark pateræ inferred to be active from color ratio images, thus confirming that these are hot spots. Plain Language Summary We mapped the hot spot distribution on Io's surface by analyzing the images acquired by the JIRAM instrument onboard the Juno spacecraft. We identified 242 hot spots, including 23 not present in other catalogs. A large number of the new hot spots identified are in the polar regions, specifically in the northern hemisphere. The comparison between our work and the most recent and updated catalog reveals that JIRAM detected 82% of the most powerful hot spots previously identified and half of the intermediate‐power hot spots, thus showing that these are still active. JIRAM detected 16 out of the 34 faint hot spots previously reported. The resolution of JIRAM may not have been sufficient to detect these faint hot spots, or activity might have faded or stopped. Key Points We produced a new Io hot spot map based on Juno/JIRAM data We identified 242 hot spots, including 23 previously undetected The latitudinal hot spot distribution is uneven with a larger concentration at the poles
Journal Article
Jupiter’s interior and deep atmosphere
2017
On 27 August 2016, the Juno spacecraft acquired science observations of Jupiter, passing less than 5000 kilometers above the equatorial cloud tops. Images of Jupiter's poles show a chaotic scene, unlike Saturn's poles. Microwave sounding reveals weather features at pressures deeper than 100 bars, dominated by an ammonia-rich, narrow low-latitude plume resembling a deeper, wider version of Earth's Hadley cell. Near-infrared mapping reveals the relative humidity within prominent downwelling regions. Juno's measured gravity field differs substantially from the last available estimate and is one order of magnitude more precise. This has implications for the distribution of heavy elements in the interior, including the existence and mass of Jupiter's core. The observed magnetic field exhibits smaller spatial variations than expected, indicative of a rich harmonic content.
Journal Article
NiTi SMA Superelastic Micro Cables: Thermomechanical Behavior and Fatigue Life under Dynamic Loadings
by
Delgado, João M. P. Q.
,
Lima, Antonio G. B.
,
Grassi, Estephanie N. D.
in
Analysis
,
Cables
,
Design
2022
Shape memory alloy (SMA) micro cables have a wide potential for attenuation of vibrations and structural health monitoring due to energy dissipation. This work evaluates the effect of SMA thermomechanical coupling during dynamic cycling and the fatigue life of NiTi SMA micro cables submitted to tensile loadings at frequencies from 0.25 Hz to 10 Hz. The thermomechanical coupling was characterized using a previously developed methodology that identifies the self-heating frequency. When dynamically loaded above this frequency, the micro cable response is dominated by the self-heating, stiffening significantly during cycling. Once above the self-heating frequency, structural and functional fatigues of the micro cable were evaluated as a function of the loading frequency for the failure of each individual wire. All tests were performed on a single wire with equal cross-section area for comparison purposes. We observed that the micro cable’s functional properties regarding energy dissipation capacity decreased throughout the cycles with increasing frequency. Due to the additional friction between the filaments of the micro cable, this dissipation capacity is superior to that of the single wire. Although its fatigue life is shorter, its delayed failure compared to a single wire makes it a more reliable sensor for structural health monitoring.
Journal Article
Clusters of cyclones encircling Jupiter’s poles
by
Ingersoll, A. P.
,
Plainaki, C.
,
Tosi, F.
in
639/33/445/823
,
639/33/445/846
,
Computational fluid dynamics
2018
Visible and infrared images obtained from above each pole of Jupiter by the Juno spacecraft reveal polygonal patterns of large cyclones; it is unknown how these cyclones evolved, or how they persist without merging.
Polygonal cyclones around Jupiter's poles
Jupiter's colourful low-latitude weather bands turn into cyclones at high latitudes, but the polar region is not visible from Earth and was poorly characterized by previous spacecraft. Alberto Adriani and colleagues report visible and infrared observations of Jupiter's polar regions made by the Juno spacecraft, which is in a highly elliptical polar orbit. They find that the cyclones create persistent polygonal patterns. There are eight circumpolar cyclones rotating around a single cyclone in the north, while the South Polar Cyclone is circled by five such features. The authors do not know how these cyclones evolved to their current state or how they persist without merging.
The familiar axisymmetric zones and belts that characterize Jupiter’s weather system at lower latitudes give way to pervasive cyclonic activity at higher latitudes
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. Two-dimensional turbulence in combination with the Coriolis β-effect (that is, the large meridionally varying Coriolis force on the giant planets of the Solar System) produces alternating zonal flows
2
. The zonal flows weaken with rising latitude so that a transition between equatorial jets and polar turbulence on Jupiter can occur
3
,
4
. Simulations with shallow-water models of giant planets support this transition by producing both alternating flows near the equator and circumpolar cyclones near the poles
5
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6
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7
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. Jovian polar regions are not visible from Earth owing to Jupiter’s low axial tilt, and were poorly characterized by previous missions because the trajectories of these missions did not venture far from Jupiter’s equatorial plane. Here we report that visible and infrared images obtained from above each pole by the Juno spacecraft during its first five orbits reveal persistent polygonal patterns of large cyclones. In the north, eight circumpolar cyclones are observed about a single polar cyclone; in the south, one polar cyclone is encircled by five circumpolar cyclones. Cyclonic circulation is established via time-lapse imagery obtained over intervals ranging from 20 minutes to 4 hours. Although migration of cyclones towards the pole might be expected as a consequence of the Coriolis β-effect, by which cyclonic vortices naturally drift towards the rotational pole, the configuration of the cyclones is without precedent on other planets (including Saturn’s polar hexagonal features). The manner in which the cyclones persist without merging and the process by which they evolve to their current configuration are unknown.
Journal Article
Juno observations of spot structures and a split tail in Io-induced aurorae on Jupiter
2018
Like Earth, Jupiter has aurorae generated by energetic particles hitting its atmosphere. Those incoming particles can come from Jupiter's moons Io and Ganymede. Mura et al. used infrared observations from the Juno spacecraft to image the moon-generated aurorae. The pattern induced by Io showed an alternating series of spots, reminiscent of vortices, and sometimes split into two arcs. Aurorae related to Ganymede could also show a double structure. Although the cause of these unexpected features remains unknown, they may provide a way to examine how the moons produce energetic particles or how the particles propagate to Jupiter. Science , this issue p. 774 Auroral features induced on Jupiter by the moons Io and Ganymede have complex spatial structures. Jupiter’s aurorae are produced in its upper atmosphere when incoming high-energy electrons precipitate along the planet’s magnetic field lines. A northern and a southern main auroral oval are visible, surrounded by small emission features associated with the Galilean moons. We present infrared observations, obtained with the Juno spacecraft, showing that in the case of Io, this emission exhibits a swirling pattern that is similar in appearance to a von Kármán vortex street. Well downstream of the main auroral spots, the extended tail is split in two. Both of Ganymede’s footprints also appear as a pair of emission features, which may provide a remote measure of Ganymede’s magnetosphere. These features suggest that the magnetohydrodynamic interaction between Jupiter and its moon is more complex than previously anticipated.
Journal Article
The Surface Composition and Temperature of Asteroid 21 Lutetia As Observed by Rosetta/VIRTIS
2011
The Visible, InfraRed, and Thermal Imaging Spectrometer (VIRTIS) on Rosetta obtained hyperspectral images, spectral reflectance maps, and temperature maps of the asteroid 21 Lutetia. No absorption features, of either silicates or hydrated minerals, have been detected across the observed area in the spectral range from 0.4 to 3.5 micrometers. The surface temperature reaches a maximum value of 245 kelvin and correlates well with topographic features. The thermal inertia is in the range from 20 to 30 joules meter⁻² kelvin⁻¹ second⁻⁰.⁵, comparable to a lunarlike powdery regolith. Spectral signatures of surface alteration, resulting from space weathering, seem to be missing. Lutetia is likely a remnant of the primordial planetesimal population, unaltered by differentiation processes and composed of chondritic materials of enstatitic or carbonaceous origin, dominated by iron-poor minerals that have not suffered aqueous alteration.
Journal Article
Optimizing the Gating System for Rapid Investment Casting of Shape Memory Alloys: Computational Numerical Analysis for Defect Minimization in a Simple-Cubic Cell Structure
by
Albuquerque, Carlos E. S.
,
De Araujo, Carlos J.
,
Delgado, João M. P. Q.
in
Additive manufacturing
,
Alloys
,
Aluminum bronzes
2023
With the aid of virtual prototyping and casting numerical simulation, this work presents the optimization of an injection system used in a non-traditional investment casting process that applies perpendicular centrifugal force to inject the molten metal into refractory plaster molds. In this study, advanced techniques of simulation and production of complex geometries in Computer-Aided Design CAD (Computer-Aided Design) are used in the design of the casting system of a miniaturized simple-cubic cell structure. The cast part has a complex shape profile and needs a high surface finish with strict dimensional tolerance. The alloy used to fill the mold is an aluminum bronze shape memory alloy (SMA). CAD was used to model the part and the proposed models for casting optimization. ProCAST software was used for the numerical simulation of the casting process. Experimental parameters were used as input data for the numerical simulation. The simulation results were analyzed focusing on the identification of defects in the Cu–Al–Mn SMA simple-cubic structures. Different feeding systems have been designed to eliminate the identified defects. Concerning the molten recirculation, the optimal nozzle model has a truncated cone profile, with a larger radius of 6.5 mm, a smaller radius of 2.0 mm and a height of 8.0 mm (called here model 3). Experimental observations from cast SMA parts agree with the simulated results of the optimized nozzle model 3. In addition to the elimination of alloy recirculation with the nozzle optimization in this work, the shrinkage porosity at the upper base of the part was eliminated with the addition of a compensation volume close to the region where porosity is more intense. By exploring the possibilities offered by commercial software, the work contributes to advance the knowledge and application of the non-traditional investment casting process, highlighting its advantages and potential applications.
Journal Article
Nutritional assessment and medical dietary therapy for management of obesity in patients with non-dialysis chronic kidney disease: a practical guide for endocrinologist, nutritionists and nephrologists. A consensus statement from the Italian society of endocrinology (SIE), working group of the club nutrition–hormones and metabolism; the Italian society of nutraceuticals (SINut), club ketodiets and nutraceuticals “KetoNut-SINut”; and the Italian society of nephrology (SIN)
2024
Purpose
Chronic kidney disease (CKD) is a serious health concern with an estimated prevalence of about 13.4% worldwide. It is cause and consequence of various comorbidities, including cardiovascular diseases. In parallel, common pathological conditions closely related to ageing and unhealthy dietary habits increase the risk of CKD development and progression, including type 2 diabetes and obesity. Among these, obesity is either independent risk factor for new onset kidney disease or accelerates the rate of decline of kidney function by multiple mechanisms. Therefore, the role of diets aimed at attaining weight loss in patients with obesity is clearly essential to prevent CKD as to slow disease progression. Various dietary approaches have been licensed for the medical dietary therapy in CKD, including low-protein diet and Mediterranean diet. Interestingly, emerging evidence also support the use of low-carbohydrate/ketogenic diet (LCD/KD) in these patients. More specifically, LCD/KDs may efficiently promote weight loss, improve metabolic parameters, and reduce inflammation and oxidative stress, resulting in a dietary strategy that act globally in managing collateral conditions that are directly and indirectly related to the kidney function.
Conclusion
This consensus statement from the Italian Society of Endocrinology (SIE), working group of the Club Nutrition – Hormones and Metabolism; the Italian Society of Nutraceuticals (SINut), Club Ketodiets and Nutraceuticals
“KetoNut-SINut”
; and the Italian Society of Nephrology (SIN) is intended to be a guide for Endocrinologist, Nutritionists and Nephrologist who deal with the management of patients with obesity with non-dialysis CKD providing a practical guidance on assessing nutritional status and prescribing the optimal diet in order to best manage obesity to prevent CKD and its progression to dialysis.
Graphical abstract
Journal Article
The adipose tissue and the involvement of the renin–angiotensin–aldosterone system in cardiometabolic syndrome
by
Borghi, F.
,
Sevá-Pessôa, B.
,
Grassi-Kassisse, D. M.
in
Adipocytes
,
Adipose tissue
,
Adipose Tissue - metabolism
2016
Cardiometabolic diseases are linked to a cluster of modifiable factors, including risk factors closely related to central adiposity. Chronic renin–angiotensin–aldosterone system (RAAS) activation has far-reaching effects on cardiometabolic risk and is a substantial contributor to this clinical condition. RAAS components are locally expressed in the vessels and adipose tissue. This review appoints RAAS, through the classical and the alternative view, as the main mediator of the cross-talk in cardiometabolic syndrome.
Journal Article
Infrared Thermography Measurements over a Tail-Plane Model of a Large Passenger Aircraft
by
Riccobene, L.
,
Gibertini, G.
,
Zanotti, A.
in
Aerial thermography
,
Aerodynamic characteristics
,
Infrared imaging
2022
In the frame of the CleanSky 2 MONNALISA project, a wind-tunnel campaign is planned to test a tail-plane model of a large passenger aircraft by using different measurement techniques. Wind-tunnel test results obtained over a systematic series of model geometries will be used to thoroughly validate a low-order numerical method based on physical modelling that will be developed in the project to evaluate the non-linear aerodynamic characteristics of aircraft lifting surfaces. The present paper describes the main results of the infrared thermography measurements performed in the first wind-tunnel entry to be used to tune RANS solvers and for the fine calibration of the low-order numerical method.
Journal Article