Further Exploration of Controlled and Automatic Memory Processes in Early Alzheimer's Disease.

The authors' aim in this study was to explore automatic and controlled processes in Alzheimer's disease (AD) by using a variant of the word-stem completion task that applies the process-dissociation procedure. Several methodological precautions were taken in order to limit problems observed in previous studies (e.g., poor task sensitivity, ceiling and/or floor effects, no control over comprehension of instructions). Our results (a) confirmed the marked deterioration in controlled processes and (b) showed that when psychometric constraints were limited, automatic memory processes were preserved in AD. These data are in line with those from more global studies in suggesting that AD is characterized by an early deterioration in controlled processes and an initial preservation of automatic processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Functional analysis of ZNF85 KRAB zinc finger protein, a member of the highly homologous ZNF91 family

We previously identified the ZNF85 (HPF4) KRAB zinc finger gene, a member of the human ZNF91 family. Here, we show that the ZNF85 gene is highly expressed in normal adult testis, in seminomas, and in the NT2/D1 teratocarcinoma cell line. Immunocytochemical localization of a panel of beta-Gal/ZNF85 fusion proteins revealed that ZNF85 contains at least one nuclear localization signal located in the spacer region connecting the KRAB domain with the zinc finger repeats. Bacterially expressed ZNF85 zinc finger domain bound strongly and exclusively to DNA in vitro in a zinc-dependent manner. The KRAB(A) domain of the ZNF85 protein and of several other members of the ZNF91 family exhibited repressing activity when tested in Gal4 fusion protein assays. The repression was significantly enhanced by the addition of the KRAB (B) domain, whereas further addition of other conserved regions had no effect. The ZNF85 KRAB(A) and (B) domains in vitro bound several nuclear proteins that might constitute critical cofactors for repression.     

Background estimation under rapid gain change in thermal imagery

We consider detection of moving ground vehicles in airborne sequences recorded by a thermal sensor with automatic gain control, using an approach that integrates dense optic flow over time to maintain a model of background appearance and a foreground occlusion layer mask. However, the automatic gain control of the thermal sensor introduces rapid changes in intensity that makes this difficult. In this paper we show that an intensity-clipped affine model of sensor gain is sufficient to describe the behavior of our thermal sensor. We develop a method for gain estimation and compensation that uses sparse flow of corner features to compute the affine background scene motion that brings pairs of frames into alignment prior to estimating change in pixel brightness. Dense optic flow and background appearance modeling is then performed on these motion-compensated and brightness-compensated frames. Experimental results demonstrate that the resulting algorithm can segment ground vehicles from thermal airborne video while building a mosaic of the background layer, despite the presence of rapid gain changes.     

"Facial expressions of emotion influence memory for facial identity in an automatic way": Correction to D'Argembeau and Van der Linden (2007).

Reports an error in "Facial expressions of emotion influence memory for facial identity in an automatic way" by Arnaud D'Argembeau and Martial Van der Linden (Emotion, 2007[Aug], Vol 7[3], 507-515). The image printed for Figure 3 was incorrect. The correct image is provided in the erratum. (The following abstract of the original article appeared in record 2007-11660-005.) Previous studies indicate that the encoding of new facial identities in memory is influenced by the type of expression displayed by the faces. In the current study, the authors investigated whether or not this influence requires attention to be explicitly directed toward the affective meaning of facial expressions. In a first experiment, the authors found that facial identity was better recognized when the faces were initially encountered with a happy rather than an angry expression, even when attention was oriented toward facial features other than expression. Using the Remember/Know/Guess paradigm in a second experiment, the authors found that the influence of facial expressions on the conscious recollection of facial identity was even more pronounced when participants' attention was not directed toward expressions. It is suggested that the affective meaning of facial expressions automatically modulates the encoding of facial identity in memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Oxydation electrochimique de la N,N-dimethyl-mesidine (DMM) dans l'acetonitrile en presence de trimethoxy-1, 3, 5 benzene (TMB). Role du produit d'addition du cation iminium de la DMM sur le TMB

The electrochemical oxidation of DMM in acetonitrile (0.1 M LiClO₄) in the presence of TMB gives initially the unstable N-méthyl, N-(2,4,6-trimethoxybenzyl)-mesidine (III), resulting from the addition of TMB to the iminium cation (II) of DMM. However, (III) is itself oxidisable at a lower potential than DMM. Therefore, as soon as it is formed (III) is oxidized into two isomeric cations (IV) and (V). The fate of these cations depends on the circumstances. They may undergo hydrolysis, and, in the presence of diethylphosphonate they may react with the latter to give the products (XIII) and (XV).Moreover, the amine (III) is cleaved in acid medium to N-methyl-mesidine and a benzylic cation. The benzylic cation reacts with TMB to give not only (IX) but also a derivative of (IX), namely (X), having three methoxylated aromatic rings.As has been shown earlier [1], the oxidation of DMM also gives the dimer (VI) and its corresponding iminium cation, which is also capable of reacting with TMB.     

Recovering Occlusion Boundaries from an Image

Occlusion reasoning is a fundamental problem in computer vision. In this paper, we propose an algorithm to recover the occlusion boundaries and depth ordering of free-standing structures in the scene. Rather than viewing the problem as one of pure image processing, our approach employs cues from an estimated surface layout and applies Gestalt grouping principles using a conditional random field (CRF) model. We propose a hierarchical segmentation process, based on agglomerative merging, that re-estimates boundary strength as the segmentation progresses. Our experiments on the Geometric Context dataset validate our choices for features, our iterative refinement of classifiers, and our CRF model. In experiments on the Berkeley Segmentation Dataset, PASCAL VOC 2008, and LabelMe, we also show that the trained algorithm generalizes to other datasets and can be used as an object boundary predictor with figure/ground labels.     

Implicit/explicit memory dissociation in Alzheimer's disease: The consequence of inappropriate processing?

Dual-process theories of recognition posit that perceptual fluency contributes to both familiarity-based explicit recognition and perceptual priming. However, the priming-without-recognition dissociation, as observed through the intact mere exposure effect and impaired recognition in patients with Alzheimer's disease (AD), might indicate that familiarity and perceptual priming are functionally distinct. This study investigated whether the AD patients' processing strategies at testing may explain this priming-without-recognition dissociation. First, we replicated the priming-without-recognition effect in 16 patients who exhibited intact exposure effects despite null recognition. Second, we showed that, under identical conditions, inducing a holistic processing strategy during recognition testing increased AD patients' recognition--performance was similar for AD patients and healthy control participants. Furthermore, prompting analytic processing during both priming and recognition tasks decreased AD patients' performance in both tasks. These findings suggest that the extent to which AD patients use perceptual fluency in priming and recognition tasks is contingent on their processing approach. The choice of processing strategy may depend on how difficult patients perceive the task to be. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Discriminative Random Fields

In this research we address the problem of classification and labeling of regions given a single static natural image. Natural images exhibit strong spatial dependencies, and modeling these dependencies in a principled manner is crucial to achieve good classification accuracy. In this work, we present Discriminative Random Fields (DRFs) to model spatial interactions in images in a discriminative framework based on the concept of Conditional Random Fields proposed by lafferty et al.(2001). The DRFs classify image regions by incorporating neighborhood spatial interactions in the labels as well as the observed data. The DRF framework offers several advantages over the conventional Markov Random Field (MRF) framework. First, the DRFs allow to relax the strong assumption of conditional independence of the observed data generally used in the MRF framework for tractability. This assumption is too restrictive for a large number of applications in computer vision. Second, the DRFs derive their classification power by exploiting the probabilistic discriminative models instead of the generative models used for modeling observations in the MRF framework. Third, the interaction in labels in DRFs is based on the idea of pairwise discrimination of the observed data making it data-adaptive instead of being fixed a priori as in MRFs. Finally, all the parameters in the DRF model are estimated simultaneously from the training data unlike the MRF framework where the likelihood parameters are usually learned separately from the field parameters. We present preliminary experiments with man-made structure detection and binary image restoration tasks, and compare the DRF results with the MRF results. Sanjiv Kumar is currently with Google Research, Pittsburgh, PA, USA. His contact email is: sanjivk@google.com.     

Stereo perception and dead reckoning for a prototype lunar rover

This paper describes practical, effective approaches to stereo perception and dead reckoning, and presents results from systems implemented for a prototype lunar rover operating in natural, outdoor environments.The stereo perception hardware includes a binocular head mounted on a motion-averaging mast. This head provides images to a normalized correlation matcher, that intelligently selects what part of the image to process (saving time), and subsamples the images (again saving time) without subsampling disparities (which would reduce accuracy). The implementation has operated successfully during long-duration field exercises, processing streams of thousands of images.The dead reckoning approach employs encoders, inclinometers, a compass, and a turn-rate sensor to maintain the position and orientation of the rover as it traverses. The approach integrates classical odometry with inertial guidance. The implementation succeeds in the face of significant sensor noise by virtue of sensor modelling, plus extensive filtering.The stereo and dead reckoning components are used by an obstacle avoidance planner that projects a finite number of arcs through the terrain map, and evaluates the traversability of each arc to choose a travel direction that is safe and effective. With these components integrated into a complete navigation system, a prototype rover has traversed over 1 km in lunar-like environments.