Inductive learning spatial attention

This paper investigates the automatic induction of spatial attention from the visual observation of objects manipulated on a table top. In this work, space is represented in terms of a novel observer-object relative reference system, named Local Cardinal System, defined upon the local neighbourhood of objects on the table. We present results of applying the proposed methodology on five distinct scenarios involving the construction of spatial patterns of coloured blocks

Time-dependent changes in membrane excitability during glucose-induced bursting activity in pancreatic β cells

In our companion paper, the physiological functions of pancreatic β cells were analyzed with a new β-cell model by time-based integration of a set of differential equations that describe individual reaction steps or functional components based on experimental studies. In this study, we calculate steady-state solutions of these differential equations to obtain the limit cycles (LCs) as well as the equilibrium points (EPs) to make all of the time derivatives equal to zero. The sequential transitions from quiescence to burst–interburst oscillations and then to continuous firing with an increasing glucose concentration were defined objectively by the EPs or LCs for the whole set of equations. We also demonstrated that membrane excitability changed between the extremes of a single action potential mode and a stable firing mode during one cycle of bursting rhythm. Membrane excitability was determined by the EPs or LCs of the membrane subsystem, with the slow variables fixed at each time point. Details of the mode changes were expressed as functions of slowly changing variables, such as intracellular [ATP], [Ca2+], and [Na+]. In conclusion, using our model, we could suggest quantitatively the mutual interactions among multiple membrane and cytosolic factors occurring in pancreatic β cells

Dendritic Hold and Read: A Gated Mechanism for Short Term Information Storage and Retrieval

Two contrasting theories have been proposed to explain the mechanistic basis of short term memory. One theory posits that short term memory is represented by persistent neural activity supported by reverberating feedback networks. An alternate, more recent theory posits that short term memory can be supported by feedforward networks. While feedback driven memory can be implemented by well described mechanisms of synaptic plasticity, little is known of possible molecular and cellular mechanisms that can implement feedforward driven memory. Here we report such a mechanism in which the memory trace exists in the form of glutamate-bound but Mg2+-blocked NMDA receptors on the thin terminal dendrites of CA1 pyramidal neurons. Because glutamate dissociates from subsets of NMDA receptors very slowly, excitatory synaptic transmission can leave a silent residual trace that outlasts the electrical activity by hundreds of milliseconds. Read-out of the memory trace is possible if a critical level of these bound-but-blocked receptors accumulates on a dendritic branch that will allow these quasi-stable receptors to sustain a regenerative depolarization when triggered by an independent gating signal. This process is referred to here as dendritic hold and read (DHR). Because the read-out of the input is not dependent on repetition of the input and information flows in a single-pass manner, DHR can potentially support a feedforward memory architecture

Disordered Boson Systems: A Perturbative Study

A hard-core disordered boson system is mapped onto a quantum spin 1/2 XY-model with transverse random fields. It is then generalized to a system of spins with an arbitrary magnitude S and studied through a 1/S expansion. The first order 1/S expansion corresponds to a spin-wave theory. The effect of weak disorder is studied perturbatively within such a first order 1/S scheme. We compute the reduction of the speed of sound and the life time of the Bloch phonons in the regime of weak disorder. Generalizations of the present study to the strong disordered regime are discussed.Comment: 27 pages, revte

Essential and checkpoint functions of budding yeast ATM and ATR during meiotic prophase are facilitated by differential phosphorylation of a meiotic adaptor protein, Hop1

A hallmark of the conserved ATM/ATR signalling is its ability to mediate a wide range of functions utilizing only a limited number of adaptors and effector kinases. During meiosis, Tel1 and Mec1, the budding yeast ATM and ATR, respectively, rely on a meiotic adaptor protein Hop1, a 53BP1/Rad9 functional analog, and its associated kinase Mek1, a CHK2/Rad53-paralog, to mediate multiple functions: control of the formation and repair of programmed meiotic DNA double strand breaks, enforcement of inter-homolog bias, regulation of meiotic progression, and implementation of checkpoint responses. Here, we present evidence that the multi-functionality of the Tel1/Mec1-to-Hop1/Mek1 signalling depends on stepwise activation of Mek1 that is mediated by Tel1/Mec1 phosphorylation of two specific residues within Hop1: phosphorylation at the threonine 318 (T318) ensures the transient basal level Mek1 activation required for viable spore formation during unperturbed meiosis. Phosphorylation at the serine 298 (S298) promotes stable Hop1-Mek1 interaction on chromosomes following the initial phospho-T318 mediated Mek1 recruitment. In the absence of Dmc1, the phospho-S298 also promotes Mek1 hyper-activation necessary for implementing meiotic checkpoint arrest. Taking these observations together, we propose that the Hop1 phospho-T318 and phospho-S298 constitute key components of the Tel1/Mec1- based meiotic recombination surveillance (MRS) network and facilitate effective coupling of meiotic recombination and progression during both unperturbed and challenged meiosis

Electronic and Magnetic Properties of Partially-Open Carbon Nanotubes

On the basis of the spin-polarized density functional theory calculations, we demonstrate that partially-open carbon nanotubes (CNTs) observed in recent experiments have rich electronic and magnetic properties which depend on the degree of the opening. A partially-open armchair CNT is converted from a metal to a semiconductor, and then to a spin-polarized semiconductor by increasing the length of the opening on the wall. Spin-polarized states become increasingly more stable than nonmagnetic states as the length of the opening is further increased. In addition, external electric fields or chemical modifications are usable to control the electronic and magnetic properties of the system. We show that half-metallicity may be achieved and the spin current may be controlled by external electric fields or by asymmetric functionalization of the edges of the opening. Our findings suggest that partially-open CNTs may offer unique opportunities for the future development of nanoscale electronics and spintronics.Comment: 6 figures, to appear in J. Am. Chem. So

Violência autoinfligida por intoxicação exógena em um serviço de urgência e emergência

RESUMO Objetivo Analisar as violências autoinfligidas por intoxicação exógena notificadas em um serviço de saúde. Métodos Estudo epidemiológico, retrospectivo e analítico realizado em um serviço de urgência e emergência do município de Teresina, Piauí. Procedeu-se nos meses de janeiro e fevereiro de 2015, mediante análise de todos os casos de violência autoinfligida por intoxicação exógena notificados no Sistema de Informação de Agravos de Notificação, no período de 2009 a 2014. O teste qui-quadrado de Pearson foi utilizado na análise. Resultados Foram notificadas 277 vítimas de violência autoinfligida por intoxicação exógena, sendo que 10,5% morreram por suicídio. Houve associação entre o óbito e as variáveis idade, escolaridade, zona de ocorrência e tipo de exposição, assim como entre o tipo de exposição e a quantidade de agentes utilizados. Conclusão Os resultados fornecem subsídios para a definição de estratégias de prevenção considerando os grupos vulneráveis e a complexidade dos fatores associados à violência autoinfligida

Molecular and morphological validation of the species of the genus Actinia (Actiniaria: Actiniidae) along the Atlantic Iberian Peninsula

The discrimination between the several species of the genus Actinia occurring in the Northeastern Atlantic and Mediterranean has been made analyzing morphological characters, with emphasis on external coloration patterns and morphology of cnidom structures. In Iberia, the occurrence of more than two species of Actinia has been suggested, but its validity is yet to be confirmed. In this paper, the identity of the species of the genus Actinia occurring along the Atlantic Iberian coast is investigated, analyzing morphological and molecular procedures. For this purpose, genetic data was collected from 140 individuals and two genetic markers were amplified and sequenced (the nuclear 28S and the mitochondrial 16S ribosomal genes). The genetic identification was corroborated by morphological analysis of individuals representing each of the genetic groups found. This procedure led to the identification of three species occurring in the studied area – Actinia equina (L.), A. fragacea Tugwell and A. schmidti Monteiro, Sole-Cava & Thorpe.Fundação para a Ciência e Tecnologia - FCTinfo:eu-repo/semantics/publishedVersio

Antimicrobial synergism against different lineages of methicillin-resistant Staphylococcus aureus carrying SCCmec IV

Aim To evaluate the synergistic activity of antimicrobial drugs against lineages of methicillin-resistant Staphylococcus aureus (MRSA) carrying SCCmec IV. The biofilm production and related genes were also detected. Methods and Results Forty two MRSA isolates were tested for biofilm production and related genes. Biofilm/biomass susceptibility to gentamicin (G), linezolid (L), rifampicin (R) and vancomycin (V) was determined for six isolates from three lineages prevalent in Rio de Janeiro hospitals in concentrations ranging from 0·25 to 64 μg ml−1. Biomass was evaluated by microtitre plate test and number of viable cells (CFU cm−2) and inspected by epifluorescence microscopy. All isolates presented the icaA and sasG genes, but only 38% were biofilm producers. There were 50 and 45% biomass reductions when concentrations ≥4 μg ml−1 of R or L and ≥16 μg ml−1 of G or V, respectively, were used. Synergism tests produced a 55% biomass reduction with R2lg ml1 + G16lg ml1 , R2lg ml1 + L2lg ml1 , R2lg ml1 + V4lg ml1 , and L2lg ml1 + V4lg ml1 . Number of viable cells was reduced from 2 to 3 logs with R2lg ml1 + L2lg ml1 and R2lg ml1 + V4lg ml1 . Conclusions Synergisms involving R plus L and R plus V caused important reductions in biofilm/biomass and the number of viable cells. Drug combinations should be considered in the chemotherapies of MRSA-SCCmec IV infections. Significance and Impact of the Study Biofilms in MRSA infections restrict the clinical choice of antimicrobials. Thus, knowledge of the best options for monotherapy and drug synergisms could improve clinical results.This study was supported by grants from Fundacao Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro (FAPERJ), Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq), Coordenacao de Aperfeicoamento Pessoal de Nivel Superior (CAPES), Fundacao Universitaria Jose Bonifacio (FUJB) and Programa de Nucleos de Excelencia (PRONEX). The financial support through the projects: PTDC/SAUSAP/113196/2009/ FCOMP-01-0124-FEDER-016012; PEst-OE/EQB/LA0023/2013; 'BioHealth-Biotechnology and Bioengineering approaches to improve health quality', NORTE-07-0124-FEDER-000027, co-funded by the Programa Operacional Regional do Norte, QREN; RECI/BBB-EBI/0179/2012/FCOMP-01-0124-FEDER-027462