Growth points in research on memory and hippocampus.

We present an overview of two of our ongoing projects relating processes in the hippocampus to memory. We are trying to understand why retrograde amnesia occurs after damage to the hippocampus. Our experiments establish the generality of several new retrograde amnesia phenomena that are at odds with the consensus view of the role of the hippocampus in memory. We show in many memory tasks that complete damage to the hippocampus produces retrograde amnesia that is equivalent for recent and remote memories. Retrograde amnesia affects a much wider range of memory tasks than anterograde amnesia. Normal hippocampal processes can interfere with retention of a long-term memory stored outside the hippocampus. We conclude that the hippocampus competes with nonhippocampal systems during memory encoding and retrieval. Finally, we outline a project to understand and manipulate adult hippocampal neurogenesis in order to repair damaged hippocampal circuitry to recover lost cognitive functions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparative study of analytical and numerical algorithms for designing reinforced concrete sections under biaxial bending

This paper presents a comparative study of different integration methods of stresses (both analytical and numerical) for concrete sections subjected to axial loads and biaxial bending. Such methods are applied to circular and rectangular sections. The constitutive equation used is a parabola-rectangle from the Eurocode-2. The comparison was performed with regard to the accuracy and the computational speed of each method. The objective of the paper is to determine which of the integration methods compared is more efficient in computing the interaction surfaces for rectangular and circular sections. The analytical method proposed by Barros et al. [Barros MHFM, Barros A, Ferreira C. Closed form solution of optimal design of rectangular reinforced concrete sections. Eng Comput 2004;21(7):761–76] for rectangular sections is compared with the numerical method termed “modified thick layer integration” proposed by Bonet et al. [Bonet JL, Romero ML, Miguel PF, Fernandez MA. A fast stress integration algorithm for reinforced concrete sections with axial loads and biaxial bending. Comput Struct 2004;82(2–3):213–25] and with the well-known fiber method. Furthermore, two new methods are proposed for circular sections: one analytical and one numerical based on the Gauss–Legendre quadrature. The results of both methods are compared with the classical layer decomposition method.     

Stochastic independence of color-vision mechanisms confirmed by a subthreshold summation paradigm

We have used a subthreshold summation protocol to analyze spatial color-color interaction. By means of a CRT color monitor, we measured the threshold contours for a spatial frequency of 0.5 cycles/degree. Heterochromatic flicker photometry was used to obtain isoluminance. The results suggest that the blue-yellow (b-y) and red-green (r-g) contrast thresholds remained unchanged by the addition of fixed r-g and b-y subthreshold pedestals. Our subthreshold summation data then support the stochastic independence of colorvision mechanisms derived from Mullen and Sankeralli's work [Vision Res. 39, 733 (1999)] despite the differences that exist between the two experimental methods.     

Fatty acids composition and proximate of 7 fish species of Isla de Pascua

During the last years the study of fatty acids belonging to omega 3 family in marine foods has been emphasized due to their beneficial effects on cardiovascular diseases, which are the main cause of death in occidental countries, as described by literature. In order to obtain more information about the fatty acid composition of the main marine species fat constituent, usually consumed by Eastern Island population, seven fish species were analyzed: Maito (Acanthurus leucopareius), Matuko (Bodianus vulpinus), Marau (Myripristis tiki), Nanue (Kiphosus bigibus). Moki (Mori and Marari, Anampses caeruleopunctatus), Puia (Girellops nebulosus) and Raea (Cheilodactilus plessisi). Fatty acid profile and proximate analysis were determined for each species. According to its fat content, Nanue and Marari showed the highest lipid percentage, with values of 2.8 and 3.6% respectively. Fatty acid profile expressed as methyl esters percentage indicated that the most important group was that of the saturated fatty acids (SFA 35.1-54%), followed by the polyunsaturated fatty acids group (PUFA, 22-42.5%). Palmitic acid was the most important between saturated fatty acids, while oleic acid was the main fatty acid between the monounsaturated group. In omega-3 family fatty acids, eicosapentaenoic acid (EPA, C20:5w3) and docosahexaenoic acid (DHA, C22:6w3) were the most important, with values in a range between 2.0-12% and 1.8-18.3%, respectively. Omega-6 family showed a higher content in arachidonic acid (AA, C20:4w6) with values between 1.9 and 10%. Considering the fatty acid composition and the fat content, Marari was the highest in w-3 and w-6 fatty acid contribution, with values of 850 and 240 mg per one hundred grams of edible portion respectively.     

A Gesture Based Interface for Human-Robot Interaction

Service robotics is currently a highly active research area in robotics, with enormous societal potential. Since service robots directly interact with people, finding natural and easy-to-use user interfaces is of fundamental importance. While past work has predominately focussed on issues such as navigation and manipulation, relatively few robotic systems are equipped with flexible user interfaces that permit controlling the robot by natural means. This paper describes a gesture interface for the control of a mobile robot equipped with a manipulator. The interface uses a camera to track a person and recognize gestures involving arm motion. A fast, adaptive tracking algorithm enables the robot to track and follow a person reliably through office environments with changing lighting conditions. Two alternative methods for gesture recognition are compared: a template based approach and a neural network approach. Both are combined with the Viterbi algorithm for the recognition of gestures defined through arm motion (in addition to static arm poses). Results are reported in the context of an interactive clean-up task, where a person guides the robot to specific locations that need to be cleaned and instructs the robot to pick up trash.     

Effect of 3 storage temperatures on the quality of kiwi fruit pulp concentrated at a reduced pressure

The effect of three storage temperatures (0, -9 and -18 degrees C) of the kiwi-fruit pulp reduced pressure concentrate, by a period of 3 months, in the physical (soluble solids, water activity, consistency and color), chemistry (pH, acidity, ascorbic acid, chlorophyll and pheophytin) and sensorial (appearance, aroma, acidity, sweetness, color and flavor) characteristics were studied. The greater deterioration was produced in the stored pulp to 0 degree C, while to -9 degrees C there is no significative differences, on the other hand, the kiwi-fruit pulp stored to -18 degrees C maintained large part of the original characteristics. It was observed that while the temperature and storage time increased, vitamin C and chlorophyll contents decreased, varying significantly consistency, color and appearance of product. The rest of the analyzed variables did not present significative differences during storage.     

Controlled clinical assay in Clonidine, arginine aspartate, alpha-ketoglutarate of Ornithine and Ciproheptadine as growth stimulants in children with short stature

Eighty-one healthy prepubertal children of short stature, between two and twelve years of age, were divided into four homogeneous groups. Each group was treated with a placebo for one year and for a second year with one of the following drugs (double blind): clonidine (CI), arginine asprate (AA), ornithine alphaketoglutare (OKG), or cyproheptadine (Cp). CI and OKG did not better the standard deviation of height. AA and Cp did, but to no greater extent than the placebo. The growth rate did not change in any group. The ratio of bone age/chronological age was significantly higher at the end of the OKG year than at the end of the year with placebo, a difference that was not found in any other group. The prognosis of adult height (TW2) did not change in any group. The standard deviation of weight increased in all groups, both with the placebo and the various drugs, without significant differences between the groups. The CI caused frequent clinical side effects, including a reversible increase in transaminases in one child. The Cp stimulated hunger. The AA and OKG did not produce side-effects and the placebo increased appetite in 11% of the children. Somatomedin C was significantly higher after one year with Cp than after one year with the placebo, significantly higher after the placebo than after CI and AA and there was no difference between the treatment with the placebo and OKG. Growth hormone values in a 24 hour urine sample were so scattered that we do not consider them helpful.(ABSTRACT TRUNCATED AT 250 WORDS)     

Takayasu's arteritis as a cause of renovascular hypertension in a non-Asian population

Takayasu's disease (TD) is a chronic inflammatory arteritis which affects the aorta and its main branches and occasionally the pulmonary artery. Its cause is not known. Clinical manifestations are due to the intensity and location of arterial inflammation in the acute phase, as well as chronic arterial stenosis over time; 50% of patients have hypertension. Although TD appears to be more common in Asia, increasing numbers of patients of different races are observed in Western countries. The most important pathogenetic mechanism of hypertension seems to be through renal artery stenosis. We show here seven Caucasian hypertensive patients with TD and renovascular stenosis and arterial hypertension. One case was diagnosed in the acute phase of the disease, while in the others diagnosis was established in an advanced occlusive phase. Basic diagnosis was established by angiographic study, with biopsy confirmation in two cases. All patients had at least three of the six criteria listed as diagnostic of TD (by the American College of Reumatology). All patients had the following criteria: age of disease onset before 40 years (symptoms or findings related to TD), vascular bruits in different areas and all patients also had aortic and renal arterial stenosis with some lesions of the main aortic branches. Six of them had claudication of the extremities. We describe their clinical, analytical and angiographic features and also the therapeutic approach. We discuss the aetiopathogenic mechanisms of hypertension in this disease and suggest that TD is not an unusual cause of vasculorenal hypertension.