1,306 research outputs found
Cognitive maps in imagery neglect
No full textPatients with imagery neglect (RI+) show peculiar difficulties in orienting themselves in the environment. Navigational impairments could be due to a deficit in creating or using a mental representation of the environment (Guariglia, Piccardi, Iaria, Nico, & Pizzamiglio, 2005) or, according to the BBB model (Burgess, Becker, King, & O'Keefe, 2001), to a specific deficit in a mechanism that transforms an allocentric representation into an egocentric one and vice versa. Previous studies, however, do not allow discerning between a deficit in forming or in using a cognitive map, taking no notice of the fact that these are two different abilities underlain by different neuroanatomical areas, which could be independently impaired. Furthermore, the BBB model has never been verified in a population of brain-damaged patients. Therefore, we administered two tasks that separately assess the ability to create and use a cognitive map of the environment to 28 right brain-damaged patients (4 patients with imagery neglect and 4 patients with perceptual neglect) and 11 healthy participants. RI+ patients showed no specific deficit in creating or using a cognitive map, but failed to transform an egocentric representation of the environment into an allocentric one and vice versa, as predicted by the BBB model. (C) 2012 Elsevier Ltd. All rights reserved.Patients with imagery neglect (RI+) show peculiar difficulties in orienting themselves in the environ- ment. Navigational impairments could be due to a deficit in creating or using a mental representation of the environment (Guariglia, Piccardi, Iaria, Nico, & Pizzamiglio, 2005) or, according to the BBB model (Burgess, Becker, King, & O’Keefe, 2001), to a specific deficit in a mechanism that transforms an allocentric representation into an egocentric one and vice versa.
Previous studies, however, do not allow discerning between a deficit in forming or in using a cognitive map, taking no notice of the fact that these are two different abilities underlain by different neuroanatom- ical areas, which could be independently impaired. Furthermore, the BBB model has never been verified in a population of brain-damaged patients.
Therefore, we administered two tasks that separately assess the ability to create and use a cognitive map of the environment to 28 right brain-damaged patients (4 pat
Private medical insurance and saving: evidence from the British household panel survey
No full textThis paper investigates whether individuals in Britain save to self-insure against health risk. In particular, we use the British Household Panel Survey for the years 1996 to 1998 to test the hypothesis that those individuals who are not covered by private medical insurance, and are therefore more prone to health risk, tend to save more than those who are covered. Our findings, which are based on a wide range of econometric specifications, always reject this hypothesis, suggesting that health risk is not a factor which induces British individuals to save more
Landmark Recognition and Mental Route Navigation Disorders in Patients with Imagery Neglect and Perceptual Neglect
No full textThe complex relationship between perceptual neglect and imagery neglect is still not completely understand because, at least in part, these disorders depend on are associated with, different neural systems and can be dissociated even in the same patient (Beschin, Basso, & Della Sala, 2000). Recent studies show that imagery neglect affects specific mechanisms underlying human orientation. In particular, it impairs the ability to manipulate mental representations of the environment and thus prevents the use of previous navigational experience (see for instance Guariglia et al., 2005; Piccardi, 2009; Guariglia & Piccardi, 2010). In this study, we compared the route learning and delayed recall task performance of imagery neglect patients with pure perceptual neglect patients, patients with no neglect and healthy participants. They had to learn a circular pathway in an unexplored area of the hospital; it included 13 landmarks and five turning points (three on the right and two on the left). During the learning phase, the participants explored the pathway three times with the examiner, who pointed out the landmarks. At the end of this phase, the participants performed two different tasks: a) Landmark Recognition Task and b) Navigational Questions. The first task included 26 pictures of landmarks (13 target pictures and 13 fillers) located along the pathway that the participants had to recognize. Fillers were the same type of stimuli as the target, but with different characteristics (e.g., two different doors). The second, delayed recall task consisted of 30 questions investigating the participants' ability to recall a learned pathway and the landmarks encountered along the way. We assessed 23 right brain-damaged patients (4 patients with pure perceptual neglect, 8 patients with imagery neglect and 11 patients without neglect) and 17 healthy participants matched for age and education. Our results showed that only patients with imagery neglect had a pervasive disorder in recognizing landmarks met along the route and in mentally navigating the previously learned pathway. Specifically, they were unable to answer navigational questions investigating their mental representation of the pathway. Differently, perceptual neglect patients were able to recognize landmarks as well as answer navigational questions in spite of their exploration disorder. Right brain-damaged patients without neglect showed no deficit on the tasks. In summary, only the imagery neglect patients were unable to build or retrieve a mental representation of the new environment and, thus, failed in performing these tasks. In fact, results showed they were deficient in using a cognitive map of the environment. It is still unknown whether the deficit observed in imagery neglect patients is due to difficulty in building a mental map, recalling it from memory or using it during navigation, leaving unknown the exact point in which the navigational process is compromised
Shock-cell noise investigation on a subsonic/supersonic coaxial jet
No full textThe work is aimed at the experimental investigation of shock-cell noise on a coaxial jet with subsonic primary stream and supersonic secondary stream. This kind of noise is nowadays an important component of the total noise emitted by aeronautic engines, particularly affecting cabin noise in cruise conditions.
In this thesis, the design and commissioning of a new supersonic coaxial jet rig, at the von Karman Institute for Fluid Dynamics (BE), are discussed, with a specific focus on the design choices that have been made to obtain good flow quality, low background noise and the possibility to perform a variety of flow and acoustic measurements. The maximum achievable Mach number at the outlet of the primary (central) and secondary (annular) nozzles is equal to 2.2, with a baseline operating point being M_p=0.89, M_s=1.21.
To commission the facility, several test campaigns on a supersonic single stream jet were conducted using PIV in synchronous with microphones mounted on a polar antenna. Multiple screech harmonics and subharmonics tones have been documented, showing a directivity pattern similarly to the supersonic broadband noise (BBSAN).
Turbulence integral length scales have been computed using correlation functions. The average of Reynolds shear stress fields shows the presence of lobes in the jet near field which are the trace of a standing wave caused by the screech.
Following the commissioning, the coaxial jet has been investigated. Multiple combinations of pressure conditions for the primary and secondary flows have been tested. Acoustic measurements have been performed in synchronous with the PIV, which has been applied for the first time in the literature on a supersonic coaxial flow.
The presence of both screech and broadband noise was recorded in the majority of the tests, and a directivity pattern was recognized for the latter. For a certain pressure conditions, the screech tone naturally disappeared. Experimental evidences suggest this may be related to a complex shock interaction occurring at the end of the primary nozzle.
A simple method to infer the screeching dynamics from the spatial correlation functions was proposed. The correlation suggests the presence of a pulsation (or breathing) motion of the internal jet, which is cause/effect of the screech. A second screech mode was also retrieved from acoustic data, for which, the correlation functions suggest the presence of a sinusoidal motion of the internal jet
Creatine combined with branched-chain amino acids supplement in speleological practice : a scientific controlled trial
No full textDuring speleological activities physical conditions are constant with respect to time. Creatine is a natural compound present in muscular tissue; in its phosphorylated form it can produce great amounts of energy rapidly and independently from sugar consumption. In consideration of specific athletic efforts and unique environment, we evaluate the effects of energy replenishers with creatine combined with branched-chain amino acids on caving performances with a controlled trial. The trial's primary goal was to evaluate the increase of athletic performance after creatine administration on a group of cavers during a cave trip with different characteristics. A second goal was to analyze the effects of branched-chain amino acids and mineral salts taken before the exertion, for the same period of time. Ten healthy cavers were treated with creatine combined with branched-chain amino acids or placebo before a cave trip. Subsequently the same group performed the same exercise inverting the treatments. Recovery time seemed to be improved by creatine administration showing reduced fatigue. Even if some observations don't reach the statistical significance, the analysis of all the data shows a trend to an improvement of nearly all parameters in the treated subjects. Laboratory data relating to muscular stress highlight a significantly minor muscular damage in the treated subjects. This might be explained with the double effect of creatine and branched-chain amino acids. Time performances showed little, non significant differences. It is possible that the dosages administered are not sufficient to improve time performances, and their effects are limited to recovery time and muscular damage
De la comprensión del bien a la voluntad de amor a Dios : evolución de la doctrina agustiniana sobre felicidad y virtud
No full textFil: Guariglia, Osvaldo. Universidad de Buenos Aires; Argentina.Fil: Guariglia, Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.101 ref.By the end of his life, Augustine condemms his earlier conception of happiness in his work of youth, De beata vita, with the following words: 'In this book it dislikes me that I mentioned repeatedly the Fortune and that I said that in the time of this life the happy life dwells in the wise's soul'. Against this view, he asserts now that 'the only true happy life is the future life' (retrac. I, 2). During the forty years between both works, Augustine gave away his classical heritage, creating his own theological thought, in which 'happy or good life' of the classical thinkers shifts from this life to the future one. This new turn in the ethical thought weighty consequences upon the ancient moral of virtues
De la comprensión del bien a la voluntad de amor a Dios : evolución de la doctrina agustiniana sobre felicidad y virtud
No full textFil: Guariglia, Osvaldo. Universidad de Buenos Aires; Argentina.Fil: Guariglia, Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.101 ref.By the end of his life, Augustine condemms his earlier conception of happiness in his work of youth, De beata vita, with the following words: 'In this book it dislikes me that I mentioned repeatedly the Fortune and that I said that in the time of this life the happy life dwells in the wise's soul'. Against this view, he asserts now that 'the only true happy life is the future life' (retrac. I, 2). During the forty years between both works, Augustine gave away his classical heritage, creating his own theological thought, in which 'happy or good life' of the classical thinkers shifts from this life to the future one. This new turn in the ethical thought weighty consequences upon the ancient moral of virtues
Design of a facility for shock-cell noise investigation on a subsonic/supersonic coaxial jet
No full textShock-cell noise is an aeroacoustic phenomenon that occurs in aeronautic engines when the nozzle is not adapted to the atmospheric pressure. In civil aircraft at cruise the secondary flow is often supersonic, thus the onset of a shock-cells system and broadband shock-associated noise as a consequence. This paper aims to describe the design of the new facility FAST (Free jet AeroacouSTic laboratory), completed in 2015, with the aim to investigate experimentally the shock-cell noise phenomenon on a dual stream jet.
The rig consists of a coaxial open jet with supersonic capability for both primary and secondary flow. A coaxial silencer is used to remove the spurious noise coming from the feeding lines. The design has been validated by the use of CFD simulations. A preliminary experimental test campaign with the single supersonic jet is presented. Fine scale PIV coupled with a microphone array in the far field have been compared with analogous research in this field
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