Search results for "vep"
showing 9 items of 39 documents
Evaluating the Effect of Stimuli Color and Frequency on SSVEP
2020
Brain&ndash
Dynamic wavefront sensing and correction with low-cost twisted nematic spatial light modulators
2010
Off-the-shelf spatial light modulators (SLMs), like twisted nematic liquid crystal displays (TNLCDs) used in projection systems, show some interesting features such as high spatial resolution, easy handling, wide availability, and low cost. We describe a compact adaptive optical system using just one TNLCD to measure and compensate optical aberrations. The current system operates at a frame rate of the order of 10 Hz with a four-level codification scheme. Wavefront estimation is performed through conventional Hartmann–Shack sensing architecture. The system has proved to work properly with a maximum rms aberration of 0. 76 μm and wavefront gradient of 50 rad/mm at a wavelength of 514 nm. The…
Property (w) and perturbations II
2008
AbstractThis note is a continuation of a previous article [P. Aiena, M.T. Biondi, Property (w) and perturbations, J. Math. Anal. Appl. 336 (2007) 683–692] concerning the stability of property (w), a variant of Weyl's theorem, for a bounded operator T acting on a Banach space, under finite-dimensional perturbations K commuting with T. A counterexample shows that property (w) in general is not preserved under finite-dimensional perturbations commuting with T, also under the assumption that T is a-isoloid.
Property (w) and perturbations III
2009
AbstractThe property (w) is a variant of Weyl's theorem, for a bounded operator T acting on a Banach space. In this note we consider the preservation of property (w) under a finite rank perturbation commuting with T, whenever T is polaroid, or T has analytical core K(λ0I−T)={0} for some λ0∈C. The preservation of property (w) is also studied under commuting nilpotent or under injective quasi-nilpotent perturbations. The theory is exemplified in the case of some special classes of operators.
Femtosecond Raman time-resolved molecular spectroscopy
2004
International audience; The applicability of several femtosecond time resolved non-linear coherent techniques such as Raman induced polarization spectroscopy (RIPS), degenerate four-wave mixing (DFWM) and coherent anti-Stokes Raman spectroscopy (CARS) for molecular spectroscopy is presented. All methods rely on the initial coherent excitation of molecular states producing wavepackets, whose time evolution is then measured. In the case of RIPS and DFWM only pure rotational transitions are involved, whereas in CARS vibrational states can be excited. First the methodology of concentration and temperature measurements using RIPS in gas mixtures involving N2, CO2, O2, and N2O is shown. In additi…
Neurocognitive Markers During Prolonged Breath-Holding in Freedivers: An Event-Related EEG Study
2019
Since little is known concerning the psychological, cognitive, and neurophysiological factors that are involved in and important for phases of prolonged breath-holding (pBH) in freedivers, the present study uses electroencephalography (EEG) to investigate event-related neurocognitive markers during pBH of experienced freedivers that regularly train pBH. The purpose was to determine whether the well-known neurophysiological modulations elicited by hypoxic and hypercapnic conditions can also be detected during pBH induced hypoxic hypercapnia. Ten experienced free-divers (all male, aged 35.10 ± 7.89 years) were asked to hold their breath twice for 4 min per instance. During the first pBH, a ch…
The importance of novel ecosystems for biodiversity : a study of ground beetles (Carabidae) on afforested fields
2014
Metsien hävittäminen, maanviljely ja muut ympäristöä muokkaavat toimet muuttavat ekosysteemejä kasvavissa määrin. Tämän seurauksena syntyy poikkeuksellisia, ihmisen toiminnasta peräisin olevia ekosysteemejä. Näiden uusekosysteemien merkitys monimuotoisuudelle kasvaa lähitulevaisuudessa kun ihmisen vaikutus Maahan lisääntyy. Metsitetyt pellot voidaan monessa tapauksessa lukea uusekosysteemeihin: lannoituksella on pitkäaikaisia vaikutuksia maaperän fysikaalisiin ominaisuuksiin ja ravinteiden määrä on metsitetyillä pelloilla suurempi kuin tavallisissa metsissä. Kasvillisuuden sukkession tarkkaa lopputulosta ei vielä tiedetä. Metsitetyt pellot käsittävät 300 000 hehtaaria Suomen pinta-alasta ja…
Print-on-Demand ja Euroopan Neuvosto
2000
POTENZIALI EVOCATI VISIVI (PEV) IN NEONATI DA GRAVIDANZA PLURIMA: RELAZIONE CON LA DISCORDANZA IN PESO (AGA VS SGA)
2009
Premessa: I PEV consentono di valutare nel neonato lo sviluppo delle vie ottiche e del SNC. Un ritardo della maturazione morfologica del tracciato, una marcata riduzione di ampiezza, o un significativo aumento di latenza delle principali componenti è frequente in neonati con encefalopatia ipossico ischemica od emorragica, o affetti da patologia cerebrale sia congenita che secondaria a grave compromissione sistemica. Nelle gravidanze plurime è frequente il rilievo di una discordanza per il peso alla nascita (neonati AGA e SGA). Obiettivo: Valutare in un campione selezionato costituito da nati da gravidanza plurima, prevalentemente pretermine e con assenza di fattori di rischio perinatali per…