132 research outputs found

    Advanced GN&C Technologies for TAEM: Flight Test Results of the Italian Unmanned Space Vehicle

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    This paper describes the guidance, navigation and control challenges posed by the Unmanned Space Vehicles Program. Within the framework of this program the Italian Aerospace Research Center has conceived several advanced GN&C technologies useful in the Terminal Area Energy Management phase of a re-entry flight pattern. These technologies were flight tested during the first two dropped transonic flight tests (DTFT1 and DTFT2) of the program. More specifically, this paper will present the design of the adaptive guidance algorithms developed to accomplish the mission objectives of the DTFT2 flight test. Flight results will be shown in order to state the performance of the guidance strategy putting in evidence, where possible, its most promising aspects for future TAEM applications

    GNC Post Flight Analysis of the Italian Dropped Transonic Flight Tests

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    The Italian Aerospace Research Centre (CIRA), in the framework of the Unmanned Space Vehicles (USV) Program, has developed several advanced Guidance, Navigation and Control technologies for the Terminal Area Energy Management (TAEM) phase of a re-entry ight. These technologies were in-flight tested during the first two dropped transonic flight tests (DTFT1 and DTFT2) of the program. These missions allowed CIRA to investigate critical technological aspects related to the autonomous execution of a typical TAEM phase of a re-entry flight, from a velocity of about Mach 2 down to the typical Approach/Landing Interface speed of Mach 0.5 and below. This paper presents flight tests results and post flight data analysis of these missions. How technological innovations in the Guidance, Navigation and Control domain can contribute to a more autonomous, more safe and less costly future generation of reusable launch vehicles is well stated in open literature. In the USV program, focus was given to adaptive guidance with on-line trajectory re-planning capabilities and to robust and fault tolerant control, as key enabling technologies for atmospheric re-entry and hypersonic flight. Obviously, the complexity of such missions also required dedicated research on advanced methodologies in the field of robustness analysis, design and verification of GNC systems for highly uncertain and non-linear systems. Methodologies for vehicle model identification from flight data have been also included in this technological road map to maximize the scientific return from the flight tests. Model identification methodologies for processing flight data are frequently used to validate and improve a pre-flight aerodynamic data-base and, specifically, to reduce the associated uncertainties. However in this field conventional techniques need to be improved because the USV flight tests have a non-stationary trajectory and specific identification manoeuvres should be avoided being hazardous for the mission. More specifically, the problem of the identification of the aerodynamic model of the Italian Unmanned Space Vehicle was solved through a multi-step approach, where the aerodynamic coefficients are identified first and, in a following phase, a set of model parameters are updated. The methodology was applied to actual flight data, acquired during the two dropped transonic flight tests

    Single Amino Acid Arginine Deprivation Triggers Prosurvival Autophagic Response in Ovarian Carcinoma SKOV3

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    Autophagy is a process of cytosol-to-lysosome vesicle trafficking of cellular constituents for degradation and recycling of their building blocks. Autophagy becomes very important for cell viability under different stress conditions, in particular under amino acid limitation. In this report we demonstrate that single amino acid arginine deprivation triggers profound prosurvival autophagic response in cultured human ovarian cancer SKOV3 cells. In fact, a significant drop in viability of arginine-starved SKOV3 cells was observed when autophagy was inhibited by either coadministration of chloroquine or transcriptional silencing of the essential autophagy protein BECLIN 1. Enzymatic arginine deprivation is a novel anticancer therapy undergoing clinical trials. This therapy is considered nontoxic and selective, as it allows controlling the growth of malignant tumours deficient in arginine biosynthesis. We propose that arginine deprivation-based combinational treatments that include autophagy inhibitors (e.g., chloroquine) may produce a stronger anticancer effect as a second line therapy for a subset of chemoresistant ovarian cancers

    Growing in the darkness: predation ability and cannibalism in cave-born larvae of fire salamander, Salamandra salamandra (Linnaeus, 1758)

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    Crescere al buio: abilit\ue0 predatoria e cannibalismo in larve di salamandra pezzata, Salamandra salamandra nate in grotta. La salamandra pezzata in diverse aree carsiche del proprio areale pu\uf2 deporre le larve anche in ambienti ipogei come grotte naturali e artificiali. Lo scopo di questo studio \ue8 valutare se le popolazioni che utilizzano tali, inusuali, siti riproduttivi, abbiano sviluppato degli adattamenti specifici. Per tale scopo abbiamo effettuato alcuni esperimenti comportamentali sulla capacit\ue0 di predazione e sul cannibalismo. Da 20 grotte e da 20 ruscelli adiacenti abbiamo raccolto delle larve che abbiamo allevato in due differenti condizioni: in ambiente ipogeo ed in ambiente epigeo. Sia le larve da grotta che da ruscello sono state in grado di catturare prede in condizioni di buio totale. Le larve nate in grotta hanno per\uf2 mostrato una maggiore efficienza. Per quanto riguarda il cannibalismo esso \ue8 ridotto alla nascita e molto pi\uf9 accentuato dopo un mese di vita delle larve. Il grado di digiuno e la taglia delle larve influenzano l\u2019aggressivit\ue0. Non sono per\uf2 risultati evidenti effetti della provenienza delle larve o delle condizioni di allevamento

    Stoics against stoics in Cudworth's "A Treatise of Freewill"

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    In his 'A Treatise of Freewill', Ralph Cudworth argues against Stoic determinism by drawing on what he takes to be other concepts found in Stoicism, notably the claim that some things are ‘up to us’ and that these things are the product of our choice. These concepts are central to the late Stoic Epictetus and it appears at first glance as if Cudworth is opposing late Stoic voluntarism against early Stoic determinism. This paper argues that in fact, despite his claim to be drawing on Stoic doctrine, Cudworth uses these terms with a meaning first articulated only later, by the Peripatetic commentator Alexander of Aphrodisias
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