Guided growth of neurons and glia using microfabricated patterns of parylene-C on a SiO2 background

This paper describes a simple technique for the patterning of glia and neurons. The integration of neuronal patterning to Multi-Electrode Arrays (MEAs), planar patch clamp and silicon based ‘lab on a chip’ technologies necessitates the development of a microfabrication-compatible method, which will be reliable and easy to implement. In this study a highly consistent, straightforward and cost effective cell patterning scheme has been developed. It is based on two common ingredients: the polymer parylene-C and horse serum. Parylene-C is deposited and photo-lithographically patterned on silicon oxide (SiO2) surfaces. Subsequently, the patterns are activated via immersion in horse serum. Compared to non-activated controls, cells on the treated samples exhibited a significantly higher conformity to underlying parylene stripes. The immersion time of the patterns was reduced from 24 to 3 h without compromising the technique. X-ray photoelectron spectroscopy (XPS) analysis of parylene and SiO2 surfaces before and after immersion in horse serum and gel based eluant analysis suggests that the quantity and conformation of proteins on the parylene and SiO2 substrates might be responsible for inducing glial and neuronal patterning.

Access and excess in The Texas Chain Saw Massacre

Much is made of the viscerally disturbing qualities embedded in The Texas Chain Saw Massacre - human bodies are traumatised, mutilated and distorted – and the way these are matched by close and often intense access to the performers involved. Graphic violence focused on the body specifically indicates the film as a key contemporary horror text. Yet, for all this closeness to the performers, it soon becomes clear in undertaking close-analysis of the film that access to them is equally characterised by extreme distance, both spatially and cognitively. The issue of distance is particularly striking, not least because of its ramifications on engagement, which throws up various aesthetic and methodological questions concerning performers’ expressive authenticity. This article considers the lack of access to performance in The Texas Chain Saw Massacre, paying particular attention to how this fits in with contemporaneous presentations of performance more generally, as seen in films such as Junior Bonner (Sam Peckinpah, 1972). As part of this investigation I consider the affect of such a severe disruption to access on engagement with, and discussion of, performance. At the heart of this investigation lie methodological considerations of the place of performance analysis in the post-studio period. How can we perceive anything of a character’s interior life, and therefore engage with performers who we fundamentally lack access to? Does such an apparently significant difference in the way performers and their embodiment is treated mean that they can even be thought of as delivering a performance?

Antidepressant medications reduce subcortical-cortical resting-state functional connectivity in healthy volunteers

Studies have revealed abnormalities in resting-state functional connectivity in those with major depressive disorder specifically in areas such as the dorsal anterior cingulate, thalamus, amygdala, the pallidostriatum and subgenual cingulate. However, the effect of antidepressant medications on human brain function is less clear and the effect of these drugs on resting-state functional connectivity is unknown. Forty volunteers matched for age and gender with no previous psychiatric history received either citalopram (SSRI; selective serotonergic reuptake inhibitor), reboxetine (SNRI; selective noradrenergic reuptake inhibitor) or placebo for 7 days in a double-blind design. Using resting-state functional magnetic resonance imaging and seed based connectivity analysis we selected the right nucleus accumbens, the right amygdala, the subgenual cingulate and the dorsal medial prefrontal cortex as seed regions. Mood and subjective experience were also measured before and after drug administration using self-report scales. Despite no differences in mood across the three groups, we found reduced connectivity between the amygdala and the ventral medial prefrontal cortex in the citalopram group and the amygdala and the orbitofrontal cortex for the reboxetine group. We also found reduced striatal-orbitofrontal cortex connectivity in the reboxetine group. These data suggest that antidepressant medications can decrease resting-state functional connectivity independent of mood change and in areas known to mediate reward and emotional processing in the brain. We conclude that hypothesis-driven seed based analysis of resting-state fMRI supports the proposition that antidepressant medications might work by normalising the elevated resting-state functional connectivity seen in depressed patients.

Can institutional investors bias real estate portfolio appraisals? Evidence from the market downturn

This paper investigates the extent to which institutional investors may have influenced independent real estate appraisals during the financial crisis. A conceptual model of the determinants of client influence on real estate appraisals is proposed. It is suggested that the extent of clients’ ability and willingness to bias appraisal outputs is contingent upon market and regulatory environments (ethical norms and legal and institutional frameworks), the salience of the appraisal(s) to the client, financial incentives for the appraiser to respond to client pressure, organisational culture, the level of moral reasoning of both individual clients and appraisers, client knowledge and the degree of appraisal uncertainty. The potential of client influence to bias ostensibly independent real estate appraisals is examined using the opportunity afforded by the market downturn commencing in 2007 in the UK. During the market turbulence at the end of 2007, the motivations of different types of owners to bias appraisals diverged clearly and temporarily provided a unique opportunity to assess potential appraisal bias. We use appraisal-based performance data for individual real estate assets to test whether there were significant ownership effects on performance during this period. The results support the hypothesis that real estate appraisals in this period reflected the differing needs of clients.

Chaotic phase synchronization and desynchronization in an oscillator network for object selection

Object selection refers to the mechanism of extracting objects of interest while ignoring other objects and background in a given visual scene. It is a fundamental issue for many computer vision and image analysis techniques and it is still a challenging task to artificial Visual systems. Chaotic phase synchronization takes place in cases involving almost identical dynamical systems and it means that the phase difference between the systems is kept bounded over the time, while their amplitudes remain chaotic and may be uncorrelated. Instead of complete synchronization, phase synchronization is believed to be a mechanism for neural integration in brain. In this paper, an object selection model is proposed. Oscillators in the network representing the salient object in a given scene are phase synchronized, while no phase synchronization occurs for background objects. In this way, the salient object can be extracted. In this model, a shift mechanism is also introduced to change attention from one object to another. Computer simulations show that the model produces some results similar to those observed in natural vision systems.

EXPERIMENTAL AND THEORETICAL STUDY OF SHYNTESIS OF N-ALKYL-NITROIMIDAZOLES.

In this work we realized and experimental and theoretical study of the N-alkylation of nitroimidazoles. The N-alkyl-2-methyl-nitroimidazoles correspond to biologically active molecules, obtained by reaction of 2-methyl-5-nitroimidazole and different alkyl halides. This reaction showed the formation of a mixture of isomeric products in different proportions, denominated like N-alkyl-2-methyl-4-nitroimidazole and N-alkyl-2-methyl-5-nitroimidazole, respectively. The reaction suggestes the formation of a tautomeric equilibrium, which generates two nucleophilic sites susceptible to electrophilic attack by the alkyl halide. The local nucleophilic reactivity of the nitroimidazole nng is determined using local reactivity indices such as the Fukui function and the electrostatic potential, besides the electronic localization function (ELF). The Fukui function was integrated for each atom using partition schemes based on analysis of Mulliken charges and natural bond orbital (NBO). Finally the reaction profiles were assessed. The results show a minor difference in the local reactivity. Nevertheless a significant difference in energy barriers is observed explaining the formation of an isomeric product over another. These results agree quite well with the experimental data.

The web of connections between tourism companies: Structure and dynamics

Tourism destination networks are amongst the most complex dynamical systems, involving a myriad of human-made and natural resources. In this work we report a complex network-based systematic analysis of the Elba (Italy) tourism destination network, including the characterization of its structure in terms of several traditional measurements, the investigation of its modularity, as well as its comprehensive study in terms of the recently reported superedges approach. In particular, structural (the number of paths of distinct lengths between pairs of nodes, as well as the number of reachable companies) and dynamical features (transition probabilities and the inward/outward activations and accessibilities) are measured and analyzed, leading to a series of important findings related to the interactions between tourism companies. Among the several reported results, it is shown that the type and size of the Companies influence strongly their respective activations and accessibilities, while their geographical position does not seem to matter. It is also shown that the Elba tourism network is largely fragmented and heterogeneous, so that it could benefit from increased integration. (C) 2009 Elsevier B.V. All rights reserved.

Mechanosensitivity of astrocytes on optimized polyacrylamide gels analyzed by quantitative morphometry

Cells are able to detect and respond to mechanical cues from their environment. Previous studies have investigated this mechanosensitivity on various cell types, including neural cells such as astrocytes. In this study, we have carefully optimized polyacrylamide gels, commonly used as compliant growth substrates, considering their homogeneity in surface topography, mechanical properties, and coating density, and identified several potential pitfalls for the purpose of mechanosensitivity studies. The resulting astrocyte response to growth on substrates with shear storage moduli of G` = 100 Pa and G` = 10 kPa was then evaluated as a function of coating density of poly-D-lysine using quantitative morphometric analysis. Astrocytes cultured on stiff substrates showed significantly increased perimeter, area, diameter, elongation, number of extremities and overall complexity if compared to those cultured on compliant substrates. A statistically significant difference in the overall morphological score was confirmed with an artificial intelligence-based shape analysis. The dependence of the cells` morphology on PDL coating density seemed to be weak compared to the effect of the substrate stiffness and was slightly biphasic, with a maximum at 10-100 mu g ml(-1) PDL concentration. Our finding suggests that the compliance of the surrounding tissue in vivo may influence astrocyte morphology and behavior.

Automatic contour extraction from 2D neuron images

This work describes a novel methodology for automatic contour extraction from 2D images of 3D neurons (e.g. camera lucida images and other types of 2D microscopy). Most contour-based shape analysis methods cannot be used to characterize such cells because of overlaps between neuronal processes. The proposed framework is specifically aimed at the problem of contour following even in presence of multiple overlaps. First, the input image is preprocessed in order to obtain an 8-connected skeleton with one-pixel-wide branches, as well as a set of critical regions (i.e., bifurcations and crossings). Next, for each subtree, the tracking stage iteratively labels all valid pixel of branches, tip to a critical region, where it determines the suitable direction to proceed. Finally, the labeled skeleton segments are followed in order to yield the parametric contour of the neuronal shape under analysis. The reported system was successfully tested with respect to several images and the results from a set of three neuron images are presented here, each pertaining to a different class, i.e. alpha, delta and epsilon ganglion cells, containing a total of 34 crossings. The algorithms successfully got across all these overlaps. The method has also been found to exhibit robustness even for images with close parallel segments. The proposed method is robust and may be implemented in an efficient manner. The introduction of this approach should pave the way for more systematic application of contour-based shape analysis methods in neuronal morphology. (C) 2008 Elsevier B.V. All rights reserved.

Using GIS Network Analyst to Identify Suppliers for a Produce Co-op in Waterville, ME

The idea for organizing a cooperative market on Waterville Main Street was proposed by Aime Schwartz in the fall of 2008. The Co-op would entail an open market located on Main Street to provide fresh, local produce and crafts to town locals. Through shorter delivery distances and agreements with local farmers, the co-op theoretically will offer consumers lower prices on produce than can be found in conventional grocery stores, as well as an opportunity to support local agriculture. One of the tasks involved with organizing the Co-op is to source all of the produce from among the hundreds of farmers located in Maine. The purpose of this project is to show how Geographic Information System (GIS) tools can be used to help the Co-op and other businesses a) site nearby farms that carry desired produce and products, and b) determine which farms are closest to the business site. Using GIS for this purpose will make it easier and more efficient to source produce suppliers, and reduce the workload on business planners. GIS Network Analyst is a tool that provides network-based spatial analysis, and can be used in conjunction with traditional GIS technologies to determine not only the geometric distance between points, but also distance over existing networks (like roads). We used Network Analyst to find the closest produce suppliers to the Co-op for specific produce items, and compute how far they are over existing roads. This will enable business planners to source potential suppliers by distance before contacting individual farmers, allowing for more efficient use of their time and a faster planning process.

Perfil da indústria de alimentos no Brasil: 1990-1995

A pesquisa sobre o perfil da indústria de alimentos no período de 1990-95 observou uma superior participação do grupo de produtos de maior valor agregado, com destaque para os laticínios, assim como um aumento do consumo de alimentos em geral propiciado pelo aumento da renda real dos trabalhadores após o Plano Real. Constataram-se, também, ajustes aos novos padrões de competitividade devido à abertura de mercado, com conseqüências na diminuição das margens líquidas e do número de emprego.

Perspectivas Acadêmicas em São Luís: A Aproximação entre o Estudo do Turismo e a Ciência da Administração

This is a master's degree dissertation that has for main objective analyzes the relationship among the areas of the knowledge, tourism and administration, under the optics of contributions in different instances, establishing analogies and reflections, tends as empiric field, the case of the municipal district of São Luís, in Maranhão State. It approaches the epistemology analysis of the tourist phenomenon discussing the employed speeches, faiths, myths, dependence, virtues and sins in the interpretation of the study. It points subjects related to the context of higher education in tourism, establishing connections with the management in a theoretical atmosphere, demonstrating the roads of evolution of the study, as well as, it permeates on analogies and reflections with tourism. It questions on the current scenery of degree courses in tourism, making connections with beginnings management studies. The proposed study, characterized as descriptive-explanatory of object, it bases on model Tourism Education Quality (TEDQUAL) near from objectives, to involve researches - documental and a field - accomplished in the years of 2005 and 2006. As sample for quotas, accomplished four universities, to presents results the expectations of analyzed subjects (students, profesionals, employers and educators) on the group of hypotheses. That spectrum of results makes possible reflections and proposed based in analysis on perspectives in superior tourism education. The research was limited the studied area and chosen sample it intends to be a tool to show the reality found in those courses, could address academic researches and practical actions developed by the education managers.

Identidade territorial em unidades de conservação : ponto de apoio para uma análise epistemológica da questão ambiental

Esta dissertação de mestrado consiste em um estudo epistemológico da questão ambiental, baseado na análise das identidades territoriais das populações habitantes de Unidades de Conservação (UC’s). Tais populações geralmente têm um modo de vida peculiar e muito vinculado com o espaço onde vivem. Além disso, elas também têm outras percepções sobre a questão ambiental e os conceitos relacionados. Estas percepções, entretanto, geralmente são subjugadas em nome da tecnocracia presente nos órgãos e instituições que trabalham com a temática ambiental. Neste contexto, o trabalho realiza um levantamento dos impasses e conflitos existentes a partir das considerações acima expostas, e os relaciona com as visões, sobre a questão ambiental, dos diferentes grupos sociais envolvidos (poder público, setor privado, ONG´s, movimentos sociais e populações tradicionais). A esta análise acrescenta uma (re)leitura dos métodos científicos à luz da epistemologia (positivismo, neopositivismo, materialismo histórico e dialético, fenomenologia, pós-modernismo e anarquismo), e o modo como cada um deles entende os conceitos de natureza e ambiente. Após, relaciona estas concepções metodológicas com as visões dos diferentes grupos, identificando a posição mais ligada a cada um deles. Com isso, as UC’s são questionadas a partir de sua base epistêmica, que reflete a matriz de pensamento ocidental moderno, e que por sua vez tende a dicotomizar homem e natureza. Ao final, são propostas outras leituras, baseadas em outras matrizes epistemológicas, para superar os impasses relativos a este viés da questão ambiental.

Um Estudo de técnicas de aceleração para algoritmos de análise de timing funcional baseados em geração automática de teste

Este trabalho tem como objetivo estudar e avaliar técnicas para a aceleração de algoritmos de análise de timing funcional (FTA - Functional Timing Analysis) baseados em geração automática de testes (ATPG – Automatic Test Generation). Para tanto, são abordados três algoritmos conhecidos : algoritmo-D, o PODEM e o FAN. Após a análise dos algoritmos e o estudo de algumas técnicas de aceleração, é proposto o algoritmo DETA (Delay Enumeration-Based Timing Analysis) que determina o atraso crítico de circuitos que contêm portas complexas. O DETA está definido como um algoritmo baseado em ATPG com sensibilização concorrente de caminhos. Na implementação do algoritmo, foi possível validar o modelo de computação de atrasos para circuitos que contêm portas complexas utilizando a abordagem de macro-expansão implícita. Além disso, alguns resultados parciais demonstram que, para alguns circuitos, o DETA apresenta uma pequena dependência do número de entradas quando comparado com a dependência no procedimento de simulação. Desta forma, é possível evitar uma pesquisa extensa antes de se encontrar o teste e assim, obter sucesso na aplicação de métodos para aceleração do algoritmo.

Reality check for volatility models

Asset allocation decisions and value at risk calculations rely strongly on volatility estimates. Volatility measures such as rolling window, EWMA, GARCH and stochastic volatility are used in practice. GARCH and EWMA type models that incorporate the dynamic structure of volatility and are capable of forecasting future behavior of risk should perform better than constant, rolling window volatility models. For the same asset the model that is the ‘best’ according to some criterion can change from period to period. We use the reality check test∗ to verify if one model out-performs others over a class of re-sampled time-series data. The test is based on re-sampling the data using stationary bootstrapping. For each re-sample we check the ‘best’ model according to two criteria and analyze the distribution of the performance statistics. We compare constant volatility, EWMA and GARCH models using a quadratic utility function and a risk management measurement as comparison criteria. No model consistently out-performs the benchmark.