Two mechanisms for optic flow and scale change processing of looming

Published in final edited form as: J Vis. ; 11(3): . doi:10.1167/11.3.5.The detection of looming, the motion of objects in depth, underlies many behavioral tasks, including the perception of self-motion and time-to-collision. A number of studies have demonstrated that one of the most important cues for looming detection is optic flow, the pattern of motion across the retina. Schrater et al. have suggested that changes in spatial frequency over time, or scale changes, may also support looming detection in the absence of optic flow (P. R. Schrater, D. C. Knill, & E. P. Simoncelli, 2001). Here we used an adaptation paradigm to determine whether the perception of looming from optic flow and scale changes is mediated by single or separate mechanisms. We show first that when the adaptation and test stimuli were the same (both optic flow or both scale change), observer performance was significantly impaired compared to a dynamic (non-motion, non-scale change) null adaptation control. Second, we found no evidence of cross-cue adaptation, either from optic flow to scale change, or vice versa. Taken together, our data suggest that optic flow and scale changes are processed by separate mechanisms, providing multiple pathways for the detection of looming.We thank Jonathan Victor and the anonymous reviewers of the paper for feedback and suggestions regarding the stimuli used here. This work was supported by NIH grant R01NS064100 to LMV. (R01NS064100 - NIH)Accepted manuscrip

Studio comparativo delle proprietà chimico-fisiche di PICC "ex-novo"

In questo studio sono stati analizzati otto cateteri venosi centrali ad inserzione periferica (PICC), provenienti da diversi produttori, aventi medesimo diametro nominale (5 Fr) e tutti monolume. E’ possibile distinguere due classi di PICC sulla base della massima pressione di infusione applicabile: i Power Inejectable (PI) e i non Power Injectable (NPI). Tra quelli inclusi si distinguono quindi cinque NPI e tre PI. Lo scopo di questa tesi è stato quello di caratterizzare la risposta meccanica dei cateteri attraverso opportuni test e misure, al fine di poter confrontare gli otto prodotti e definire dei criteri oggettivi per supportare la fase di scelta dell'operatore sanitario. Per raggiungere questo obiettivo, è stata pianificata una procedura costituita da una serie di analisi, misurazioni e test che evidenziassero peculiarità geometriche, proprietà fisico-chimiche oltre alla risposta meccanica del PICC e del materiale. Si è innanzitutto descritta accuratamente la geometria di ogni PICC: il diametro esterno ed interno, la lunghezza e la curvatura iniziale dovuta al metodo di conservazione dei cateteri negli imballaggi. Tramite rugosimetria si è quindi estratto il profilo microscopico della superficie integrando i dati con immagini di microscopia ottica e elettronica (SEM). La risposta meccanica è stata analizzata tramite test di trazione uniassiale, analisi dinamica al variare della temperatura (DMTA) e kinking test. Le misurazioni sono state effettuate su due campioni per ogni produttore, in modo da verificare al contempo ripetibilità delle misure e affidabilità dei dati. Tramite questa procedura è stato possibile distinguere interessanti scelte adottate dalle aziende. Per quanto riguarda il packaging ogni azienda ha fornito un numero diverso di strumenti, spesso mettendo anche a disposizione materiale che non viene utilizzato, andando quindi a gravare sulla logistica di stoccaggio. Evidenti differenze sono state notate tra i metodi di conservazione del PICC all'interno della confezione, che influisce sulla curvatura iniziale del catetere. I diametri esterni oscillano fra gli 1.64 fino a 1.76 millimetri, alcuni modelli hanno una porzione prossimale conica che raggiunge i 2.3 mm. Non sono state riscontrate significative differenze dal punto di vista della rugosità superficiale e dell'analisi microscopica. Il test di trazione ha evidenziato delle disomogeneità tra campioni nella risposta meccanica, che possono incrementare il rischio clinico se non note a priori al personale ospedaliero. Inoltre ha dato indicazioni sull'utilizzo del medesimo materiale di fabbricazione da parte di tre aziende, peculiarità confermata anche dalle DMTA. Le DMTA hanno inoltre mostrato un ampio range di possibili comportamenti termici tra i vari cateteri. Complessivamente lo studio ha evidenziato la variabilità fra i modelli in commercio anche se appartenenti alla medesima classe (PI o NPI), fornendo degli strumenti alle aziende ospedaliere per la scelta del prodotto PICC

Aplicación de técnicas de big data en validación de auditorías financieras

aplicación de las técnicas de análisis de big data en los procedimientos de validación dentro de las auditoría financierasThis project is based on the creation of a work methodology for Audit based on Data Analytics. During the project, a work plan is developed to address the different cases that can be presented in the Audit, and later, three practical cases are developed resolving them by contextualizing this methodology of work. It should be noted that some parts of the method are based on improved previous ideas in order to achieve a better results. This project has been carried out in company, specifically in KPMG where they have actively participated in the necessary measure, giving the opportunity to carry out projects and thus be able to base this work on them.Este proyecto se basa en la creación de una metodología de trabajo para la Auditoría basándose en el Análisis de datos. Durante el proyecto se desarrolla un plan de trabajo para abordar los diferentes casos que se pueden presentar en Auditoría, y más adelante se desarrollan tres casos prácticos resolviendolos contextualizando esta metodología propia de trabajo. Cabe recalcar que se parte de unas ideas anteriores y se mejoran haciendo que de esta nueva manera se pueda obtener un mejor resultado. Este proyecto se ha realizado en empresa, concretamente en KPMG donde han participado de manera activa en la medida necesaria, dando la oportunidad de realizar proyectos y así poder basar en ellos este trabajo

Juvenile Rheumatoid Arthritis: Early Diagnosis, Management, and Prognosis

Rheumatoid arthritis (RA) is the major chronic rheumatic disorder of childhood. It affects as many as 250,000 American children and is slightly more common in girls than boys

Interaction of cortical networks mediating object motion detection by moving observers

Published in final edited form as: Exp Brain Res. 2012 August ; 221(2): 177–189. doi:10.1007/s00221-012-3159-8.The task of parceling perceived visual motion into self- and object motion components is critical to safe and accurate visually guided navigation. In this paper, we used functional magnetic resonance imaging to determine the cortical areas functionally active in this task and the pattern connectivity among them to investigate the cortical regions of interest and networks that allow subjects to detect object motion separately from induced self-motion. Subjects were presented with nine textured objects during simulated forward self-motion and were asked to identify the target object, which had an additional, independent motion component toward or away from the observer. Cortical activation was distributed among occipital, intra-parietal and fronto-parietal areas. We performed a network analysis of connectivity data derived from partial correlation and multivariate Granger causality analyses among functionally active areas. This revealed four coarsely separated network clusters: bilateral V1 and V2; visually responsive occipito-temporal areas, including bilateral LO, V3A, KO (V3B) and hMT; bilateral VIP, DIPSM and right precuneus; and a cluster of higher, primarily left hemispheric regions, including the central sulcus, post-, pre- and sub-central sulci, pre-central gyrus, and FEF. We suggest that the visually responsive networks are involved in forming the representation of the visual stimulus, while the higher, left hemisphere cluster is involved in mediating the interpretation of the stimulus for action. Our main focus was on the relationships of activations during our task among the visually responsive areas. To determine the properties of the mechanism corresponding to the visual processing networks, we compared subjects’ psychophysical performance to a model of object motion detection based solely on relative motion among objects and found that it was inconsistent with observer performance. Our results support the use of scene context (e.g., eccentricity, depth) in the detection of object motion. We suggest that the cortical activation and visually responsive networks provide a potential substrate for this computation.This work was supported by NIH grant RO1NS064100 to L.M.V. We thank Victor Solo for discussions regarding models of functional connectivity and our subjects for participating in the psychophysical and fMRI experiments. This research was carried out in part at the Athinoula A. Martinos Center for Biomedical Imaging at the Massachusetts General Hospital, using resources provided by the Center for Functional Neuroimaging Technologies, P41RR14075, a P41 Regional Resource supported by the Biomedical Technology Program of the National Center for Research Resources (NCRR), National Institutes of Health. This work also involved the use of instrumentation supported by the NCRR Shared Instrumentation Grant Program and/or High-End Instrumentation Grant Program; specifically, grant number S10RR021110. (RO1NS064100 - NIH; National Center for Research Resources (NCRR), National Institutes of Health; S10RR021110 - NCRR)Accepted manuscrip

Il trattamento in Terapia Intensiva dello shock cardiogeno in corso di infarto miocardico acuto con sopraslivellamento ST: risultati nell'ASL 11 Empoli dopo la riorganizzazione dell'ospedale per intensità di cure.

Vengono messi a confronto i risultati sulla mortalità intraricovero dello shock cardiogeno in corso di STEMI prima e dopo la riorganizzazione della Terapia Intensiva Cardiologica in seguito all'apertura dell'ospedale per intensità di cure dell'ASL 11 di Empoli

Long-range coupling of prefrontal cortex and visual (MT) or polysensory (STP) cortical areas in motion perception

To investigate how, where and when moving auditory cues interact with the perception of object-motion during self-motion, we conducted psychophysical, MEG, and fMRI experiments in which the subjects viewed nine textured objects during simulated forward self-motion. On each trial, one object was randomly assigned its own looming motion within the scene. Subjects reported which of four labeled objects had independent motion within the scene in two conditions: (1) visual information only and (2) with additional moving- auditory cue. In MEG, comparison of the two conditions showed: (i) MT activity is similar across conditions, (ii) late after the stimulus presentation there is additional activity in the auditory cue condition ventral to MT, (iii) with the auditory cue, the right auditory cortex (AC) shows early activity together with STS, (iv) these two activities have different time courses and the STS signals occur later in the epoch together with frontal activity in the right hemisphere, (v) for the visual-only condition activity in PPC (posterior parietal cortex) is stronger than in the auditory-cue condition. fMRI conducted for visual-only condition reveals activations in a network of parietal and frontal areas and in MT. In addition, Dynamic Granger Causality analysis showed for auditory cues a strong connection of the AC with STP but not with MT suggesting binding of visual and auditory information at STP. Also, while in the visual-only condition PFC is connected with MT, in the auditory-cue condition PFC is connected to STP (superior temporal polysensory) area. These results indicate that PFC allocates attention to the “object” as a whole, in STP to a moving visual-auditory object, and in MT to a moving visual object.Accepted manuscrip