Large-scale multielectrode recording and stimulation of neural activity

Large circuits of neurons are employed by the brain to encode and process information. How this encoding and processing is carried out is one of the central questions in neuroscience. Since individual neurons communicate with each other through electrical signals (action potentials), the recording of neural activity with arrays of extracellular electrodes is uniquely suited for the investigation of this question. Such recordings provide the combination of the best spatial (individual neurons) and temporal (individual action-potentials) resolutions compared to other large-scale imaging methods. Electrical stimulation of neural activity in turn has two very important applications: it enhances our understanding of neural circuits by allowing active interactions with them, and it is a basis for a large variety of neural prosthetic devices. Until recently, the state-of-the-art in neural activity recording systems consisted of several dozen electrodes with inter-electrode spacing ranging from tens to hundreds of microns. Using silicon microstrip detector expertise acquired in the field of high-energy physics, we created a unique neural activity readout and stimulation framework that consists of high-density electrode arrays, multi-channel custom-designed integrated circuits, a data acquisition system, and data-processing software. Using this framework we developed a number of neural readout and stimulation systems: (1) a 512-electrode system for recording the simultaneous activity of as many as hundreds of neurons, (2) a 61-electrode system for electrical stimulation and readout of neural activity in retinas and brain-tissue slices, and (3) a system with telemetry capabilities for recording neural activity in the intact brain of awake, naturally behaving animals. We will report on these systems, their various applications to the field of neurobiology, and novel scientific results obtained with some of them. We will also outline future directions

The Suaineadh Project : a stepping stone towards the deployment of large flexible structures in space

The Suaineadh project aims at testing the controlled deployment and stabilization of space web. The deployment system is based on a simple yet ingenious control of the centrifugal force that will pull each of the four daughters sections apart. The four daughters are attached onto the four corners of a square web, and will be released from their initial stowed configuration attached to a central hub. Enclosed in the central hub is a specifically designed spinning reaction wheel that controls the rotational speed with a closed loop control fed by measurements from an onboard inertial measurement sensor. Five other such sensors located within the web and central hub provide information on the surface curvature of the web, and progression of the deployment. Suaineadh is currently at an advanced stage of development: all the components are manufactured with the subsystems integrated and are presently awaiting full integration and testing. This paper will present the current status of the Suaineadh project and the results of the most recent set of tests. In particular, the paper will cover the overall mechanical design of the system, the electrical and sensor assemblies, the communication and power systems and the spinning wheel with its control system

Mortalidade entre Idosos no Estado do Paraná e no município de Foz do Iguaçu

Trabalho de Conclusão da Residência apresentado ao Programa de Residência Multiprofissional em Saúde da Família da Universidade Federal da Integração Latino- Americana, como requisito parcial para obtenção do título de Especialista em Saúde da Família na modalidade de residência. Orientador: Walfrido Svoboda. (Prof. Dr. do Curso de Saúde Coletiva - UNILA) e Coorientadora: Carmen Justina Gamarra. (Profa. Dra. do Curso de Saúde Coletiva - UNILA)Objetivo: Analisar a tendência da mortalidade entre idosos residentes no estado do Paraná e no município de Foz do Iguaçu, no período de 2001 a 2012, e mortalidade proporcional por capítulos CID-10. Método: Trata-se de um estudo descritivo, ecológico de série temporal. Os dados dos óbitos e da população idosa de 60 anos ou mais foram obtidos por meio do Sistema de Informação de mortalidade SIM/DATASUS. Foram calculadas as taxas anuais de mortalidade bruta e padronizadas por sexo e faixa etária. Para os dados de mortalidade proporcional por capítulos CID-10 foram calculados os percentuais para os anos selecionados de 2001; 2006; 2011; 2016. As informações foram tabuladas em planilhas do Excel, sendo construídas tabelas e gráficos e analisados por meio de regressão linear simples. Resultados: Observou-se tendência declinante da mortalidade dos idosos no estado do Paraná e no município de Foz do Iguaçu. Ao longo do estudo verificou-se que as doenças do aparelho circulatório constituem-se como a primeira e principal causa de óbito, seguido das neoplasias e doenças do aparelho respiratório. Conclusão: No período analisado, a tendência da mortalidade padronizadas dos idosos obteve decréscimo tanto no Estado como no município, sendo observados maiores coeficientes de mortalidade entre os homens quando comparado às mulheres.Objective: To analyze the mortality trend among elderly people living in the state of Para- ná and in the municipality of Foz do Iguaçu, from 2001 to 2012, and proportional mortality by ICD-10 chapters. Method: This is a descriptive, ecological time series study. Data on deaths and the elderly population aged 60 years and over were obtained using the SIM / Datasus Mortality Infor- mation System. Gross annual mortality rates were standardized and standardized by gen- der and age group. The information was tabulated in Excel spreadsheets, and tables and graphs were constructed and analyzed using simple linear regression. Results: In general terms, a declining trend in mortality among the elderly was observed in the state of Paraná and in the city of Foz do Iguaçu. Throughout the study it was verified that diseases of the circulatory system constitute the first and main cause of death, fol- lowed by neoplasias and diseases of the respiratory system. Conclusion: In the period analyzed, the general trend of standardized mortality among the elderly decreased both in the state and in the municipality, with higher mortality rates among men when compared to womenObjetivo: Analizar la tendencia de la mortalidad entre ancianos residentes en el estado de Paraná y en el municipio de Foz do Iguaçu, en el período de 2001 a 2012, y mortali- dad proporcional por capítulos CID-10. Método: Se trata de un estudio descriptivo, eco- lógico de serie temporal. Los datos de mortalidad y de la población de la tercera edad (mayor de 60años) fueron obtenidos por medio del sistema de información de mortalidad SIM/DATASUS. Fueron calculadas las tasas anuales de mortalidad bruta y estandariza- das por sexo y edad. Las informaciones fueron tabuladas en planillas de cálculo Micro- soft Excel, siendo construidas tablas, gráficos e analizados por medio de regresión linear simple. Resultados: En términos generales fue observada la tendencia declinante de la mortali- dad en personas de la tercera edad en el Estado de Paraná y en el Municipio de Foz de Iguazú. A lo largo de este estudio, se verifico que las enfermedades del aparato circula- torio se consideran como la primera causa de muerte, seguido por Cáncer e enfermeda- des del Aparato Respiratorio. Conclusión: En el periodo analizado, la tendencia de la mortalidad estandarizada en personas de la tercera edad obtuvo decrecimos tanto en el Estado de Paraná como en el Municipio, siendo observados mayores coeficientes de mortalidad en hombres compara- do con mujere

Position Reconstruction in Drift Chambers operated with Xe, CO2 (15%)

We present measurements of position and angular resolution of drift chambers operated with a Xe,CO$_2$(15%) mixture. The results are compared to Monte Carlo simulations and important systematic effects, in particular the dispersive nature of the absorption of transition radiation and non-linearities, are discussed. The measurements were carried out with prototype drift chambers of the ALICE Transition Radiation Detector, but our findings can be generalized to other drift chambers with similar geometry, where the electron drift is perpendicular to the wire planes.Comment: 30 pages, 18 figure

Inner retinal preservation in rat models of retinal degeneration implanted with subretinal photovoltaic arrays

Photovoltaic arrays (PVA) implanted into the subretinal space of patients with retinitis pigmentosa (RP) are designed to electrically stimulate the remaining inner retinal circuitry in response to incident light, thereby recreating a visual signal when photoreceptor function declines or is lost. Preservation of inner retinal circuitry is critical to the fidelity of this transmitted signal to ganglion cells and beyond to higher visual targets. Post-implantation loss of retinal interneurons or excessive glial scarring could diminish and/or eliminate PVA-evoked signal transmission. As such, assessing the morphology of the inner retina in RP animal models with subretinal PVAs is an important step in defining biocompatibility and predicting success of signal transmission. In this study, we used immunohistochemical methods to qualitatively and quantitatively compare inner retinal morphology after the implantation of a PVA in two RP models: the Royal College of Surgeons (RCS) or transgenic S334ter-line 3 (S334ter-3) rhodopsin mutant rat. Two PVA designs were compared. In the RCS rat, we implanted devices in the subretinal space at 4 weeks of age and histologically examined them at 8 weeks of age and found inner retinal morphology preservation with both PVA devices. In the S334ter-3 rat, we implanted devices at 6-12 weeks of age and again, inner retinal morphology was generally preserved with either PVA design 16-26 weeks post-implantation. Specifically, the length of rod bipolar cells and numbers of cholinergic amacrine cells were maintained along with their characteristic inner plexiform lamination patterns. Throughout the implanted retinas we found nonspecific glial reaction, but none showed additional glial scarring at the implant site. Our results indicate that subretinally implanted PVAs are well-tolerated in rodent RP models and that the inner retinal circuitry is preserved, consistent with our published results showing implant-evoked signal transmission

RNA sequencing analysis of human podocytes reveals glucocorticoid regulated gene networks targeting non-immune pathways

Glucocorticoids are steroids that reduce inflammation and are used as immunosuppressive drugs for many diseases. They are also the mainstay for the treatment of minimal change nephropathy (MCN), which is characterised by an absence of inflammation. Their mechanisms of action remain elusive. Evidence suggests that immunomodulatory drugs can directly act on glomerular epithelial cells or ‘podocytes’, the cell type which is the main target of injury in MCN. To understand the nature of glucocorticoid effects on non-immune cell functions, we generated RNA sequencing data from human podocyte cell lines and identified the genes that are significantly regulated in dexamethasone-treated podocytes compared to vehicle-treated cells. The upregulated genes are of functional relevance to cytoskeleton-related processes, whereas the downregulated genes mostly encode pro-inflammatory cytokines and growth factors. We observed a tendency for dexamethasone-upregulated genes to be downregulated in MCN patients. Integrative analysis revealed gene networks composed of critical signaling pathways that are likely targeted by dexamethasone in podocytes

Space charge in drift chambers operated with the Xe,CO2(15%) mixture

Using prototype modules of the ALICE Transition Radiation Detector we investigate space charge effects and the dependence of the pion rejection performance on the incident angle of the ionizing particle. The average pulse height distributions in the drift chambers operated with the Xe,CO2(15%) mixture provide quantitative information on the gas gain reduction due to space charge accumulating during the drift of the primary ionization. Our results demonstrate that the pion rejection performance of a TRD is better for tracks which are not at normal incidence to the anode wires. We present detailed simulations of detector signals, which reproduce the measurements and lend strong support to our interpretation of the measurements in terms of space charge effects.Comment: 18 pages, 10 figures, accepted for publication in Nucl.Instrum.Meth. A. Data files available at http://www-alice.gsi.de/tr

Performance of bulk SiC radiation detectors

SiC is a wide-gap material with excellent electrical and physical properties that may make it an important material for some future electronic devices. The most important possible applications of SiC are in hostile environments, such as in car/jet engines, within nuclear reactors, or in outer space. Another area where the material properties, most notably radiation hardness, would be valuable is in the inner tracking detectors of particle physics experiments. Here, we describe the performance of SiC diodes irradiated in the 24 GeV proton beam at CERN. Schottky measurements have been used to probe the irradiated material for changes in I–V characteristics. Other methods, borrowed from III–V research, used to study the irradiated surface include atomic force microscope scans and Raman spectroscopy. These have been used to observe the damage to the materials surface and internal lattice structure. We have also characterised the detection capabilities of bulk semi-insulating SiC for α radiation. By measuring the charge collection efficiency (CCE) for variations in bias voltage, CCE values up to 100% have been measured

Fixed-Parameter Tractable Distances to Sparse Graph Classes

We show that for various classes $\mathcal{C}$ of sparse graphs, and several measures of distance to such classes (such as edit distance and elimination distance), the problem of determining the distance of a given graph $\small{G}$ to $\mathcal{C}$ is fixed-parameter tractable. The results are based on two general techniques. The first of these, building on recent work of Grohe et al. establishes that any class of graphs that is slicewise nowhere dense and slicewise first-order definable is FPT. The second shows that determining the elimination distance of a graph $\small{G}$ to a minor-closed class $\mathcal{C}$ is FPT. We demonstrate that several prior results (of Golovach, Moser and Thilikos and Mathieson) on the fixed-parameter tractability of distance measures are special cases of our first method