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Time-of-flight secondary ion mass spectrometry (ToF-SIMS) imaging is used across many fields for the atomic and molecular characterization of surfaces, with both high sensitivity and high spatial resolution. When large analysis areas are required, standard ToF-SIMS instruments allow for the acquisition of adjoining tiles, which are acquired by rastering the primary ion beam. For such large area scans, tiling artifacts are a ubiquitous challenge, manifesting as intensity gradients across each tile and/or sudden changes in intensity between tiles. Such artifacts are thought to be related to a combination of sample charging, local detector sensitivity issues, and misalignment of the primary ion gun, among other instrumental factors. In this work, we investigated six different computational tiling artifact removal methods: tensor decomposition, multiplicative linear correction, linear discriminant analysis, seamless stitching, simple averaging, and simple interpolating. To ensure robustness in the study, we applied these methods to three hyperspectral ToF-SIMS data sets and one OrbiTrapSIMS data set. Our study includes a carefully designed statistical analysis and a quantitative survey that subjectively assessed the quality of the various methods employed. Our results demonstrate that while certain methods are useful and preferred more often, no one particular approach can be considered universally acceptable and that the effectiveness of the artifact removal method is strongly dependent on the particulars of the data set analyzed. As examples, the multiplicative linear correction and seamless stitching methods tended to score more highly on the subjective survey; however, for some data sets, this led to the introduction of new artifacts. In contrast, simple averaging and interpolation methods scored subjectively poorly on the biological data set, but more highly on the microarray data sets. We discuss and explore these findings in depth and present general recommendations given our findings to conclude the work.

Most object-directed limb movements can be carried out with a comfortable grasp posture. However, the orientation of an object relative to our bodies can sometimes lead us to select an uncomfortable or awkward grasp posture due to limitations imposed by the biomechanics of the arm. In a series of experiments, we identified a network of cortical areas that are engaged during the selection of movement strategies. Neurologically intact participants and two brain-damaged patients with overlapping lesions in the right posterior superior parietal lobule (pSPL) performed a grasp posture selection task in which biomechanical constraints were the primary consideration for selecting an action. The task induced states of bistable actions whereby the same stimulus gave rise to categorically different grasp postures. In a behavioral experiment, the two patients displayed a large range of manual bistability with the contralesional hand, resulting in a higher incidence of awkward grasping postures. In neurologically intact participants, a separate functional magnetic resonance imaging (fMRI) experiment revealed activation of a parieto-frontal network, which included the posterior intraparietal sulcus (pIPS) along the banks of the pSPL that was parametrically modulated by the degree of bistability in grasp posture selection. Superimposing this activation over the patients' structural MRIs revealed that the pIPS/pSPL activation in the neurologically intact participants overlapped with lesioned cortical tissue in both patients; all other areas of activation overlapped with intact cortical tissue in the patients. These results provide converging evidence that the posterior parietal cortex plays a critical role in selecting biomechanically appropriate postures during reach-to-grasp behaviors.

There is debate as to whether or not the Ebbinghaus illusion is driven by high-level cognitive size contrast mechanisms as opposed to low-level biphasic contour interactions. In this study, we examine the variability in effects that are shared between this illusion and a different illusion that cannot be explained logically by a size contrast account. This comparison revealed that nearly one quarter of the variability for one illusion is shared with the other – demonstrating how a size-contrast account cannot be the sole explanation for the Ebbinghaus illusion.

Research findings on which brain areas demonstrate fMRI adaptation to the form, orientation, and size of visual stimuli has been mixed. Studies demonstrate effects in various subdivisions of the lateral occipital cortex (LOC), including retinotopically tuned areas LO-1 and LO-2, and dorsal stream areas in the intraparietal sulcus (IPS). Therefore, we aimed to examine fMRI adaptation in four subdivisions of the LOC (LO-proper, posterior fusiform sulcus, LO-1, and LO-2) and three discrete regions in the IPS (caudal IPS, IPS-proper, and anterior IPS) to clarify the role that these structures play in form, orientation, and size processing. Participants performed three tasks which involved judging whether two serially presented novel objects shared the same form, orientation, or size. On each version of the task, one feature varied from trial-to-trial (e.g., form) while the other two features (e.g., orientation and size) were held constant. In this way, we were able to examine the unique fMRI signal changes in response to changes in form, orientation, and size in isolation. Form adaptation – a decrease in fMRI signal following repeated presentation of the same stimulus – was present in LO-proper and pFS, highlighting the role of LOC in form processing. Size repetition enhancement – an increase in fMRI signal following repeated presentations of the same stimulus – was observed in pFs. We propose that the latter result demonstrates the effects that top-down factors can have on visual areas, specifically when there is stimulus uncertainty. There was no evidence of orientation processing in any of the regions examined. Neither form adaptation nor size repetition enhancement was present in the three IPS regions-of-interest. Last, retinotopically defined LO1 and LO2 could not be reliably identified in participants and therefore we were unable to examine adaptation in these areas as we originally intended to do.

Objectif: Comparer le débit cardiaque obtenu par thermodilution (DC-TD) à celui du Doppler œsophagien (DC-DO) pendant la stabilité hémodynamique et après la stabilisation cardiaque au cours ďun pontage aortocoronarien à cœur battant (PACCB). Méthode: Avec ľapprobation du Comité de révision, nous avons recruté 58 patients devant subir un PACCB pour une comparaison simultanée du DC-TD et DC-DO à trois moments différents. Les mesures ont été enregistrées à ľaveugle, après ľinsertion de la sonde (T0), immédiatement avant et après (T1,T2) le déplacement du cœur et avant de commencer tout traitement pharmacologique, si nécessaire, pour maintenir la tension artérielle systolique à ses valeurs ďavant la mobilisation cardiaque. Des mesures ont aussi été prises avant la fermeture sternale (Tfinal). Résultats: Trois cent deux paires de données ont été analysées selon la méthode de Bland et Altman. Le biais, ľécart type (ET) du biais (précision) et le degré de concordance (biais ± 2 ET) ont été calculés. Sur la base des publications consultées, le degré le plus élevé de concordance devrait être < 0,5 L·min-1pour conclure que les deux méthodes sont interchangeables. Au T0, le biais et ľET du biais entre DC-TD et DC-DO ont été de -0,1 ± 1,0 L·min-1. Immédiatement avant la stabilisation du cœur, le biais ± ET était de 0,6 ± 1,0 L·min-1et après le déplacement du cœur, de 0,5 ± 0,8 L·min-1. Au Tfinal, le biais ± ET était de 0,7 ± 0,7 L·min-1. Conclusion: Le degré de concordance étant < 0,5 L·min-1pour toutes les mesures, sauf au T0, nous concluons que la TD et le DO ne sont pas interchangeables pendant le PACCB.

Purpose: We designed this retrospective study to assess the frequency of difficult airway and difficult intubation in patients with spasmodic torticollis and compare it to that of the general population. Methods: After Institutional Review Board approval, data were collected from the charts of all the patients with spasmodic torticollis who underwent selective peripheral denervation at our institution between 1988 and 2001. The intubation grade was determined using the Cormack and Lehane laryngoscopic classification. The best laryngeal view was recorded. Results: Data from 342 patients were available for analysis. Fourteen patients had a difficult airway. In two patients, intubation was difficult with three attempts at laryngoscopy in one patient and use of fibreoptic bronchoscopy in the other. Twelve (3.5%) patients presented with laryngoscopic grades of III or IV The combined prevalence of laryngoscopic view grade III and IV and difficult intubation was 4.4%. Conclusions: This study assesses the frequency of difficult intubation in patients suffering from spasmodic torticollis. When compared to the general population, these patients do not appear to have a higher frequency of difficult airway or difficult intubation.

Purpose: Bilateral sixth nerve palsy is a known though uncommon complication following dural puncture. The recommended treatment consists of hydration and alternate monocular occlusion. The value and the timing of an epidural blood patch (EBP) for sixth nerve palsy remains controversial as some authors have demonstrated benefits in performing an EBP early in course of the nerve palsy whereas others have not found any advantage when an EBP was performed later. Clinical features: A 40-yr-old woman developed bilateral sixth nerve palsy ten days after an unintentional dural puncture. An EBP was done within 24 hr after the onset of the symptoms and immediate improvement of the diplopia was noted by the patient and confirmed by an ophthalmologist. Complete resolution of the diplopia occurred 36 days after the dural puncture. Conclusion: Blood patching within 24 hr of the onset of diplopia may be a reasonable treatment for ocular nerve palsy as it relieved the postdural puncture headache and produced partial improvement of the diplopia.