1,721,247 research outputs found
Accelerometer-based correction of skewed horizon and keystone distortion in digital photography
No full textImproper camera orientation produces convergent vertical lines (keystone distortion) and skewed horizon lines (horizon distortion) in digital pictures; an a-posteriori processing is then necessary to obtain appealing pictures. We show here that, after accurate calibration, the camera on-board accelerometer can be used to automatically generate an alternative perspective view from a virtual camera, leading to images with residual keystone and horizon distortions that are essentially imperceptible at visual inspection. Furthermore, we describe the uncertainty on the position of each pixel in the corrected image with respect to the accelerometer noise. Experimental results show a similar accuracy for a smartphone and for a digital reflex camera. The method can find application in customer imaging devices as well as in the computer vision field, especially when reference vertical and horizontal features are not easily detectable in the image. © 2014 Elsevier B.V
TOWARDS STEADY-STATE VISUALLY EVOKED POTENTIALS BRAIN-COMPUTER INTERFACES FOR VIRTUAL REALITY ENVIRONMENTS EXPLICIT AND IMPLICIT INTERACTION
Full text linkIn the last two decades, Brain-Computer Interfaces (BCIs) have been investigated mainly for the purpose of implementing assistive technologies able to provide new channels for communication and control for people with
severe disabilities. Nevertheless, more recently, thanks to technical and scientific advances in the different research fields involved, BCIs are gaining greater attention also for their adoption by healthy users, as new interaction devices.
This thesis is dedicated to to the latter goal and in particular will deal with BCIs based on the Steady State Visual Evoked Potential (SSVEP), which in previous works demonstrated to be one of the most flexible and reliable approaches. SSVEP based BCIs could find applications in different contexts, but one which is particularly interesting for healthy users, is their adoption as new interaction devices for Virtual Reality (VR) environments and Computer Games.
Although being investigated since several years, BCIs still poses several limitations in terms of speed, reliability and usability with respect to ordinary interaction devices. Despite of this, they may provide additional, more direct and intuitive, explicit interaction modalities, as well as implicit interaction modalities otherwise impossible with ordinary devices.
This thesis, after a comprehensive review of the different research fields being the basis of a BCI exploiting the SSVEP modality, present a state-of-the-art open source implementation using a mix of pre-existing and custom software tools. The proposed implementation, mainly aimed to the interaction with VR environments and Computer Games, has then been used to perform several experiments which are hereby described as well.
Initially performed experiments aim to stress the validity of the provided implementation, as well as to show its usability with a commodity bio-signal acquisition device, orders of magnitude less expensive than commonly used ones, representing a step forward in the direction of practical BCIs for end users applications.
The proposed implementation, thanks to its flexibility, is used also to perform novel experiments aimed to investigate the exploitation of stereoscopic displays to overcome a known limitation of ordinary displays in the context of SSVEP based BCIs.
Eventually, novel experiments are presented investigating the use of the SSVEP modality to provide also implicit interaction. In this context, a first proof of concept Passive BCI based on the SSVEP response is presented and demonstrated to provide information exploitable for prospective applications
Accelerometer based horizon and keystone perspective correction
No full textBecause of improper camera orientation, pictures are often affected by perspective distortions. In this paper, we show how to use the on-board camera accelerometer to correct the horizon and keystone distortions, without requiring any human intervention. The experimental results demonstrate the feasibility of the proposed approach; they also suggest that an accurate accelerometer calibration is necessary to get a satisfying distortion removal
Pulse shape analysis for segmented germanium detectors implemented in graphics processing units
No full textPosition sensitive highly segmented germanium detectors constitute the state-of-the-art of the technology employed for γ-spectroscopy studies. The operation of large spectrometers composed of tens to hundreds of such detectors demands enormous amounts of computing power for the digital treatment of the signals. The use of Graphics Processing Units (GPUs) has been evaluated as a cost-effective solution to meet such requirements. Different implementations and the hardware constraints limiting the performance of the system are examined. © 2013 Elsevier B.V
Attribuzioni di Competenza e Calore ai Leader in Contesti Organizzativi
No full textSecondo il modello del contenuto degli stereotipi, i giudizi sociali si articolano in due dimensioni: competenza e calore. Il calore comprende caratteristiche relazionali come amichevolezza e cordialità; la competenza comprende le capacità che consentono di realizzare i propri obiettivi (ad es., intelligenza, abilità, sicurezza). Tale modello è soprattutto applicato allo studio del pregiudizio e dei rapporti intergruppi; nell’ambito della psicologia delle organizzazioni, incominciano ad apparire studi che riguardano, ad esempio, la valutazione e la selezione del personale. Nel presente contributo analizziamo competenza e calore come attributi percepiti della leadership e consideriamo le loro
relazioni con importanti variabili organizzative. Sono stati condotti due studi correlazionali, in cui si sono indagate le relazioni tra attribuzioni di
competenza e calore al proprio superiore e le seguenti variabili: burnout (esaurimento emotivo e disaffezione lavorativa, Studio 1 e 2); comportamenti di cittadinanza (Studio 1 e 2); intenzioni di turnover (Studio 2). In entrambi gli studi, è stato testato l’effetto mediatore dell’impegno organizzativo affettivo. Attraverso la somministrazione di questionari in due organizzazioni (una società di gestione del servizio idrico, una banca), ai partecipanti, dipendenti delle due organizzazioni, si chiedeva di valutare il proprio diretto superiore e di compilare le scale relative all’impegno organizzativo e alle variabili-risultato. I dati sono stati analizzati utilizzando il programma PROCESS che consente di verificare ipotesi di mediazione. I risultati hanno mostrato effetti della competenza; si è trovato, infatti, che percepire il proprio diretto superiore come competente sia correlato negativamente con il burnout e le intenzioni di lasciare l’azienda e positivamente con i comportamenti di cittadinanza. Come ipotizzato, tali relazioni risultano mediate dall’impegno affettivo. Non si sono rilevate relazioni significative nel caso del calore. Naturalmente, la ricerca va replicata in contesti lavorativi in cui il calore percepito del leader possa essere più influente. Questo contributo dimostra l’utilità di usare competenza e calore come attributi della leadership
Attribuzioni di Competenza e Calore ai Leader in Contesti Organizzativi
No full textSecondo il modello del contenuto degli stereotipi, i giudizi sociali si articolano in due dimensioni: competenza e calore. Il calore comprende caratteristiche relazionali come amichevolezza e cordialità; la competenza comprende le capacità che consentono di realizzare i propri obiettivi (ad es., intelligenza, abilità, sicurezza). Tale modello è soprattutto applicato allo studio del pregiudizio e dei rapporti intergruppi; nell’ambito della psicologia delle organizzazioni, incominciano ad apparire studi che riguardano, ad esempio, la valutazione e la selezione del personale. Nel presente contributo analizziamo competenza e calore come attributi percepiti della leadership e consideriamo le loro
relazioni con importanti variabili organizzative. Sono stati condotti due studi correlazionali, in cui si sono indagate le relazioni tra attribuzioni di
competenza e calore al proprio superiore e le seguenti variabili: burnout (esaurimento emotivo e disaffezione lavorativa, Studio 1 e 2); comportamenti di cittadinanza (Studio 1 e 2); intenzioni di turnover (Studio 2). In entrambi gli studi, è stato testato l’effetto mediatore dell’impegno organizzativo affettivo. Attraverso la somministrazione di questionari in due organizzazioni (una società di gestione del servizio idrico, una banca), ai partecipanti, dipendenti delle due organizzazioni, si chiedeva di valutare il proprio diretto superiore e di compilare le scale relative all’impegno organizzativo e alle variabili-risultato. I dati sono stati analizzati utilizzando il programma PROCESS che consente di verificare ipotesi di mediazione. I risultati hanno mostrato effetti della competenza; si è trovato, infatti, che percepire il proprio diretto superiore come competente sia correlato negativamente con il burnout e le intenzioni di lasciare l’azienda e positivamente con i comportamenti di cittadinanza. Come ipotizzato, tali relazioni risultano mediate dall’impegno affettivo. Non si sono rilevate relazioni significative nel caso del calore. Naturalmente, la ricerca va replicata in contesti lavorativi in cui il calore percepito del leader possa essere più influente. Questo contributo dimostra l’utilità di usare competenza e calore come attributi della leadership
Allergic reaction due to the liposomal component of liposomal amphotericin B
No full textA case of severe allergic reaction arising during treatment with Ambisome and unresponsive to antihistamine and steroid medication is reported. A 2.9-year-old female child with Hurler's syndrome received an allogeneic cord blood transplant from an unrelated donor. During the aplastic phase, liposomal amphotericin B (Ambisome) was administered as part of an empirical treatment for persistent fever. The patient developed an extensive maculopapular rash and severe itching that resolved only on discontinuation of the drug. The patient subsequently had interstitial pneumonia with ingravescent respiratory failure in spite of adequate antibiotic and antiviral treatment. Treatment with conventional amphotericin B was considered essential in this critically ill patient, and the conventional formulation was administered for 20 days without causing any reaction. Severe allergic reaction to Ambisome is a rare event but, taking into account that premedication or dose testing is not recommended for this formulation, careful monitoring of the patient being treated for the first time is warranted
The brain side of Information technology : an exploration with low cost EEG devices
No full textAn emerging problem in IT is how human communication, mediated by computer systems, evolves in new and unexpected ways. Diffusion of social networks, virtual reality, videogames, e-learning, mobile communication are changing the way, in particular, teen and young people interact and exchange experience and emotions. To understand and explore the effects on human beings of the new communication paradigms is a challenge that can be tackled by studying it by multiple viewpoints, from perception to high cognitive and psychological levels and recurring to advanced signal processing methods.
The availability of low cost EEG recording devices allows us to perform a large amount of experiments, providing the possibility of sound data interpretation, and setting up simulated and real environmental experiment set up.
We are less interested in the study of non-elementary perceptual phenomena, rather focused to study interpersonal or human-computer communication processes, by observing brain behaviour through EEG signal analysis. As a matter of fact, visual and auditory perception, still remain the primary means of such communication processes, but higher level brain phenomena are possibly more appealing. Experiments on EEG already demonstrate that not only a visual, motor or auditory stimulus can be detected, but also the imagination of the stimulus itself can also be detected, so opening the road to brain computer interaction.
In this paper we will present some preliminary results from experiments on music, colour perception and mono vs. stereo video viewin
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