Implicitly Weighted Methods in Robust Image Analysis

This paper is devoted to highly robust statistical methods with applications to image analysis. The methods of the paper exploit the idea of implicit weighting, which is inspired by the highly robust least weighted squares regression estimator. We use a correlation coefficient based on implicit weighting of individual pixels as a highly robust similarity measure between two images. The reweighted least weighted squares estimator is considered as an alternative regression estimator with a clear interpretation. We apply implicit weighting to dimension reduction by means of robust principal component analysis. Highly robust methods are exploited in tasks of face localization and face detection in a database of 2D images. In this context we investigate a method for outlier detection and a filter for image denoising based on implicit weighting.     

The Role of the Prefrontal Cortex in the Maintenance of Verbal Working Memory: An Event-Related fMRI Analysis.

Neuroimaging studies have been inconclusive in characterizing the role of the prefrontal cortex (PFC) for maintaining increasingly larger amounts of information in working memory (WM). To address this question, the authors collected event-related functional MRI data while participants performed an item-recognition task in which the number of to-be-remembered letters was parametrically modulated. During maintenance of information in WM, the dorsolateral and the ventrolateral PFC exhibited linearly increasing activation in response to increasing WM load. Prefrontal regions could not be distinguished from one another on the basis of load sensitivity, but the dorsolateral PFC had stronger functional connectivity with the parietal and motor cortex than the ventrolateral PFC. These results suggest an increasingly important role for the PFC in actively maintaining information as the amount of that information increases. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Multipose Binding in Molecular Docking

Molecular docking has been extensively applied in virtual screening of small molecule libraries for lead identification and optimization. A necessary prerequisite for successful differentiation between active and non-active ligands is the accurate prediction of their binding affinities in the complex by use of docking scoring functions. However, many studies have shown rather poor correlations between docking scores and experimental binding affinities. Our work aimed to improve this correlation by implementing a multipose binding concept in the docking scoring scheme. Multipose binding, i.e., the property of certain protein-ligand complexes to exhibit different ligand binding modes, has been shown to occur in nature for a variety of molecules. We conducted a high-throughput docking study and implemented multipose binding in the scoring procedure by considering multiple docking solutions in binding affinity prediction. In general, improvement of the agreement between docking scores and experimental data was observed, and this was most pronounced in complexes with large and flexible ligands and high binding affinities. Further developments of the selection criteria for docking solutions for each individual complex are still necessary for a general utilization of the multipose binding concept for accurate binding affinity prediction by molecular docking.     

Moyamoya disease in a patient with hereditary spherocytosis

The use of circulatory arrest with selective antegrade cerebral perfusion is described in a 59-year-old man who underwent thrombendarterectomy for chronic thromboembolic pulmonary hypertension. The postoperative course was uneventful. The described surgical technique may prevent the patient from cerebral sequelae especially in more complex cases.     

Cerebrospinal fluid proteins in the diagnosis of disorders of the blood-cerebrospinal fluid barrier in central nervous system diseases

BACKGROUND: Many neurological diseases are connected with the dysfunction of blood-CSF barrier. The quantitative determination of CSF proteins has already been used in the diagnosis of barrier impairments and inflammatory diseases of the central nervous system. PATIENTS: Serum and CSF, totaling 264 samples, were obtained from 15 controls and 117 patients with various diseases of the nervous system. Laurell's electroimmunoassay was used for estimation of albumin and IgG levels in serum and CSF. CSF-protein profile was evaluated according to Reiber's graph for the evaluation of the CSF-protein profile. RESULTS: The graph for the protein profile can be divided into 5 functionally different parts (1--normal range, 2, 3, 4--different types of barrier dysfunctions and 5--local humoral response in CNS without any barrier impairment). There was a good correlation of CSF-protein profiles and neurological diseases in our group of patients. CONCLUSIONS: According to our results, Reiber's graph was helpful for the diagnosis of blood-CSF-barrier dysfunctions. The graph has the following advantages: a) possibility of simultaneous assessment of the functional state of blood-CSF-barrier and the inflammatory response of the CNS, b)sensitivity for the determination of pathological local IgG-production in CNS and c) minimal number of protein assays necessary.     

The role of protocols and professional judgement in emergency medical dispatching

The task of evaluating incoming calls to Emergency Medical Services (EMS) systems in order to determine the most appropriate response is performed in many different ways in current EMS systems. At one end of the spectrum, the process is entirely dependent on the judgement of professionals, while at the other end protocols specify the exact questions to be asked and corresponding decisions. This case study describes the experience of the Montreal EMS system, Urgences santé, where professional telephone evaluation performed by nurses since 1981 was replaced by a protocolized system in 1992. During the professional era, there were many attempts to formalize the nurses' decision-making process. These first revealed that professional judgement tended to override decision-support tools that did not allow a flexible processing of the information spontaneously provided by callers. Second, the choice of a single protocol for each call was unnatural for professionals who could spontaneously integrate multiple aspects of a problem in parallel. Third, when protocols were used by professionals, it was a posteriori in order to document their decisions rather than actually support them. Fourth, the use of Artificial Intelligence (AI) methods in order to formalize professional judgement revealed its great complexity, which was confirmed by cognitive analyses of the nurses' decision-making processes. In particular, decisions of not sending EMS resources seemed to be the most difficult. These unsuccessful attempts at formalizing professional judgement led to an evaluation of its performance in terms of results, i.e. to which extent actual decisions minimized errors (both false positives and false negatives) and decision times. A random sample of 1006 calls was collected and the ideal decision was determined by concensus of experts for each call based on the patient's clinical condition. This theoretical decision was considered as a goal standard to which actual decisions were compared. Data analysis revealed that sensitivity of telephone triage (i.e. decision to send EMS resources or not) was almost perfect and specificity was 0.55. The necessary compromise between sensitivity and specificity varied with the types of decisions. Decision times were related to the urgency of the situations, more urgent calls being processed more rapidly. These results were interpreted as representing sophisticated optimization processes in professional judgement. The professional system was replaced by a non-professional protocolized system in 1992. This new system has not yet been formally evaluated in terms of results, but many sources of evidence suggest that it was accompanied by a deterioration of performance. Many contextual factors influence the organization of telephone assessment in EMS systems. This case study suggests that professional judgement may be most useful in contexts where the demand for EMS services often exceeds the availability of resources. On the other hand, protocolized systems may be more appropriate in the absence of such constraints, and where the litigation context prohibits the occurrence of any false negative.