Stable neurovisual servoing for robot manipulators

In this paper, we propose a stable neurovisual servoing algorithm for set-point control of planar robot manipulators in a fixed-camera configuration an show that all the closed-loop signals are uniformly ultimately bounded (UUB) and converge exponentially to a small compact set. We assume that the gravity term and Jacobian matrix are unknown. Radial basis function neural networks (RBFNNs) with online real-time learning are proposed for compensating both gravitational forces and errors in the robot Jacobian matrix. The learning rule for updating the neural network weights, similar to a back propagation algorithm, is obtained from a Lyapunov stability analysis. Experimental results on a two degrees of freedom manipulator are presented to evaluate the proposed controller.     

Apoptosis in the failing human heart

BACKGROUND: Loss of myocytes is an important mechanism in the development of cardiac failure of either ischemic or nonischemic origin. However, whether programmed cell death (apoptosis) is implicated in the terminal stages of heart failure is not known. We therefore studied the magnitude of myocyte apoptosis in patients with intractable congestive heart failure. METHODS: Myocardial samples were obtained from the hearts of 36 patients who underwent cardiac transplantation and from the hearts of 3 patients who died soon after myocardial infarction. Samples from 11 normal hearts were used as controls. Apoptosis was evaluated histochemically, biochemically, and by a combination of histochemical analysis and confocal microscopy. The expression of two proto-oncogenes that influence apoptosis, BCL2 and BAX, was also determined. RESULTS: Heart failure was characterized morphologically by a 232-fold increase in myocyte apoptosis and biochemically by DNA laddering (an indicator of apoptosis). The histochemical demonstration of DNA-strand breaks in myocyte nuclei was coupled with the documentation of chromatin condensation and fragmentation by confocal microscopy. All these findings reflect apoptosis of myocytes. The percentage of myocytes labeled with BCL2 (which protects cells against apoptosis) was 1.8 times as high in the hearts of patients with cardiac failure as in the normal hearts, whereas labeling with BAX (which promotes apoptosis) remained constant. The near doubling of the expression of BCL2 in the cardiac tissue of patients with heart failure was confirmed by Western blotting. CONCLUSIONS: Programmed death of myocytes occurs in the decompensated human heart in spite of the enhanced expression of BCL2; this phenomenon may contribute to the progression of cardiac dysfunction.     

Advances in Applying Computer-Aided Drug Design for Neurodegenerative Diseases

Neurodegenerative diseases (NDs) including Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis, and Huntington’s disease are incurable and affect millions of people worldwide. The development of treatments for this unmet clinical need is a major global research challenge. Computer-aided drug design (CADD) methods minimize the huge number of ligands that could be screened in biological assays, reducing the cost, time, and effort required to develop new drugs. In this review, we provide an introduction to CADD and examine the progress in applying CADD and other molecular docking studies to NDs. We provide an updated overview of potential therapeutic targets for various NDs and discuss some of the advantages and disadvantages of these tools.     

Disturbance attenuation by dynamic output feedback for input-delay systems

This paper addresses the optimal disturbance attenuation problem by output feedback for multivariable linear systems with delayed inputs. The attenuation is optimal in the sense that the controller minimizes the maximal amplitude of the plant output in response to such a disturbance. The controller is a general feedback, involving an observer, a state predictor, and a predicted state feedback. The optimal disturbance attenuation problem is formulated in terms of an equivalent system without delay. The optimal bound of the disturbance attenuation is then characterized, and it is shown that the optimal controller tends to have high gains. A necessary and sufficient condition to guarantee the existence of an optimal solution is provided using the geometric approach.     

Bioreactor Transient Exposure Activates Specific Neurotrophic Pathway in Cortical Neurons

Altered gravity forces might influence neuroplasticity and can provoke changes in biochemical mechanisms. In this contest, neurotrophins have a pivotal role, particularly nerve growth factor (NGF) and brain derived neurotrophic factor (BDNF). A suspension of dissociated cortical cells from rat embryos was exposed to 24 h of microgravity before plating in normal adherent culture system. Expression and transductional signalling pathways of NGF and BDNF were assessed at the end of maturational process (8–10 days in vitro). Rotating wall vessel bioreactor (RWV) pre-exposition did not induce changes in NGF expression and its high affinity receptor TrkA. On the contrary both BDNF expression and its high affinity receptor TrkB were strongly up-regulated, inducing Erk-5, but not Erk-1/2 activation and, in turn, MEF2C over-expression and activation. According to our previous and present results, we postulate that relatively short microgravitational stimuli, applied to neural cells during the developmental stage, exert a long time activation of specific neurotrophic pathways.     

The complexity and approximation of fixing numerical attributes in databases under integrity constraints

Consistent query answering is the problem of characterizing and computing the semantically correct answers to queries from a database that may not satisfy certain integrity constraints. Consistent answers are characterized as those answers that are invariant under all minimally repaired versions of the original database. We study the problem of repairing databases with respect to denial constraints by fixing integer numerical values taken by attributes. We introduce a quantitative definition of database repair, and investigate the complexity of several decision and optimization problems. Among them, Database Repair Problem (DRP): deciding the existence of repairs within a given distance to the original instance, and CQA: deciding consistency of answers to simple and aggregate conjunctive queries under different semantics. We provide sharp complexity bounds, identifying relevant tractable and intractable cases. We also develop approximation algorithms for the latter. Among other results, we establish: (a) The -hardness of CQA. (b) That DRP is MAXSNP-hard, but has a good approximation. (c) The intractability of CQA for aggregate queries for one database atom denials (plus built-ins), and also that it has a good approximation.     

Separating group supervision from group therapy: Avoiding epistemological confusion.

Comments on M. T. Riva and J. A. Erickson's (see record 1996-09446-001) article examining group supervision practices in psychology predoctoral internships. The author argues that extant research in the area of group supervision has already provided evidence that suggests therapy-based group supervision environments or processes are likely not effective approaches to use with trainees. It is concluded that approaching group supervision primarily as a process of learning that is best informed by pedagogy, rather than as an activity similar to group therapy in its processes and goals, may assist supervisors and researchers in finding effective and ethical methods to train psychology students. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Distribution of transposable elements in neotropical species of Drosophila

The phylogenetic distribution of transposable families, P, gypsy, hobo, I, and mariner has been analyzed in 33 species of 11 groups of neotropical Drosophila and a Drosophilidae species Zygotrica vittimaculosa, using squash blot and dot blot. Genomic DNA of almost all neotropical species tested hybridized with gypsy probe and some species showed a particularly strong hybridization signal, as D. gaucha, D. virilis, and species of flavopilosa group. The hobo element was restricted to melanogaster group and some strains of D. willistoni. Only D. simulans DNA showed hybridization to mariner probe in all species tested and D. simulans and D. melanogaster showed hybridization with I element probe. P element homologous sequence was present in D. melanogaster and all species and strains of the willistoni and saltans groups tested. The presence of at least one P-homologous sequence was detected in Drosophila mediopunctata. This one was the only P-bearing species of all six tested from the tripunctata group. Four different pairs of primers homologous to segments of the canonical sequence of D. melanogaster's P were used to amplify specific sequences from D. mediopunctata DNA, showing the occurrence of seemingly well-conserved P-homologous sequences.     

Testing an isolated system powered by solar energy and PEM fuel cell with hydrogen generation

Photovoltaic systems are widely used to power telecommunications systems in remote locations, but this is restricted by the irregular availability of solar energy. A European collaboration is developing and testing an autonomous system that combines a photovoltaic power system in combination with an electrolyzer that uses surplus power to produce hydrogen, which can be used in a PEM fuel cell when there is insufficient solar energy.     

New ribosome-inactivating proteins with polynucleotide:adenosine glycosidase and antiviral activities from Basella rubra L. and bougainvillea spectabilis Willd

New single-chain (type 1) ribosome-inactivating proteins (RIPs) were isolated from the seeds of Basella rubra L. (two proteins) and from the leaves of Bougainvillea spectabilis Willd. (one protein). These RIPs inhibit protein synthesis both in a cell-free system, with an IC50 (concentration causing 50% inhibition) in the 10(-10) M range, and by various cell lines, with IC50S in the 10(-8)-10(-6) M range. All three RIPs released adenine not only from rat liver ribosomes but also from Escherichia coli rRNA, polyadenylic acid, herring sperm DNA, and artichoke mottled crinkle virus (AMCV) genomic RNA, thus being polynucleotide:adenosine glycosidases. The proteins from Basella rubra had toxicity to mice similar to that of most type 1 RIPs (Barbieri et al., 1993, Biochim Biophys Acta 1154: 237-282) with an LD50 (concentration that is 50% lethal) < or = 8 mg.kg-1 body weight, whilst the RIP from Bougainvillea spectabilis had an LD50 > 32 mg.kg-1. The N-terminal sequence of the two RIPs from Basella rubra had 80-93% identity, whereas it differed from the sequence of the RIP from Bougainvillea spectabilis. When tested with antibodies against various RIPs, the RIPs from Basella gave some cross-reactivity with sera against dianthin 32, and weak cross-reactivity with momordin I and momorcochin-S, whilst the RIP from Bougainvillea did not cross-react with any antiserum tested. An RIP from Basella rubra and one from Bougainvillea spectabilis were tested for antiviral activity, and both inhibited infection of Nicotiana benthamiana by AMCV.