7,082 research outputs found
The core-periphery model with three regions
We study a 3-region core-periphery model Ă la Krugman and compare our results with those of the standard 2-region model. The conditions for the stability of the dispersion and concentration configurations are established. Like in the 2-region model, dispersion and concentration can be simultaneously stable. We show that the 2- region (3-region) model favors the dispersion (concentration) of economic activity. Finally, we extend the core-periphery model to the case of n regions and show that stability of concentration with 2 regions implies stability of concentration with any even number of regions.new economic geography, core-periphery
Review of catalytic systems and thermodynamics for the Guerbet condensation reaction and challenges for biomass valorization
The Guerbet condensation reaction is an alcohol coupling reaction that has been known for more than a century. Because of the increasing availability of bio-based alcohol feedstock, this reaction is of growing importance and interest in terms of value chains of renewable chemical and biofuel production. Due to the specific branching pattern of the alcohol products, the Guerbet reaction has many interesting applications. In comparison to their linear isomers, branched-chain Guerbet alcohols have extremely low melting points and excellent fluidity. This review provides thermodynamic insights and unravels the various mechanistic steps involved. A comprehensive overview of the homogeneous, heterogeneous and combined homogeneous and heterogeneous catalytic systems described in published reports and patents is also given. Technological considerations, challenges and perspectives for the Guerbet chemistry are discussed
An iOS Framework for the Indivo X Personally Controlled Health Record
The Indivo X personally controlled health record creates a channel between researchers and the patient/subject in several large scale projects. Indivo enables patients to access their health data through a web interface and, as an âapps platformâ, can be extended in functionality. Patient-facing apps, such as a medication list, may improve the data flow between researcher and patient, in both directions, and as such provide better data for the researcher and immediate benefit for the patient. However, research projects in general do not allocate large funds to patient facing apps, let alone a mobile interface. Thus we have created a framework that greatly simplifies connecting an iOS app to an Indivo X server. Our open-source framework enables novel as well as experienced iOS developers to build mobile interfaces for their research subjects, taking advantage of Indivo X
TransferĂȘncia de dispositivos de reconhecimento da agricultura orgĂąnica e apropriação local: uma anĂĄlise sobre a Rede Ecovida
Recognition mechanisms for organic agriculture have been transferred from the European Union and the United Sates of America to Brazil, along with their regulation and certification systems. Our research aims to evaluate the local adaptation and appropriation of such systems in the state of Santa Catarina, Brazil. This work is a preliminary analysis of field data collected from one of the three networks surveyed, "Rede Ecovida de Agroecologia". This network is set up to escape, as far as possible, from constraints established by a kind of recognition its members define as "official", belonging to the"certification industry", and exceedingly reductionist. The network gives, therefore, priority to direct sales to "aware" consumers. This militant practice constitutes an ambitious form of social control ofcertification, but their procedures have been situated, for a long time, in the relatively narrow space of local markets. They are confronted, however, to other options linked to wider markets with shorter action time spans, that reflect the reactivity of commercial operators to rapid changes in urban consumption models. The duration, stability and flexibility of each of these recognition systems depend largely on the dynamic imposed on the temporal and spatial contexts of their agents
Nurturing the young shoots of talent: Using action research for exploration and theory building
This is an Author's Accepted Manuscript of an article published in European Early Childhood Education Research Journal, 19(4), 433-450, 2011, copyright Taylor & Francis, available online at: http://www.tandfonline.com/10.1080/1350293X.2011.623515.This paper reports the outcomes of a set of action research projects carried out by teacher researchers in 14 local education authorities in England, working collaboratively with university tutors, over a period of three years. The common aim of all the projects was to explore practical ways of nurturing the gifts and talents of children aged fourâseven years. The project was funded by the Department of Education and Skills in England as part of the government's gifted and talented programme. The project teachers felt that their understanding of issues relating to nurturing the gifts and talents of younger children was enhanced through their engagement in the project. It was possible to map the findings of the projects to the English government's National Quality Standards for gifted and talented education which include: (1) identification; (2) effective provision in the classroom; (3) enabling curriculum entitlement and choice; (4) assessment for learning; (5) engaging with community, families and beyond. The findings are also analysed within the framework of good practice in educating children in the first years of schooling. Participating practitioners felt that action research offered them a suitable methodology to explore the complexity of the topic of giftedness through cycles of planning, action and reflection and personal theory building
Cyclic and ruled Lagrangian surfaces in complex Euclidean space
We study those Lagrangian surfaces in complex Euclidean space which are
foliated by circles or by straight lines. The former, which we call cyclic,
come in three types, each one being described by means of, respectively, a
planar curve, a Legendrian curve of the 3-sphere or a Legendrian curve of the
anti de Sitter 3-space. We also describe ruled Lagrangian surfaces. Finally we
characterize those cyclic and ruled Lagrangian surfaces which are solutions to
the self-similar equation of the Mean Curvature Flow. Finally, we give a
partial result in the case of Hamiltonian stationary cyclic surfaces
Emergence of a filamentary structure in the fireball from GRB spectra
It is shown that the concept of a fireball with a definite filamentary
structure naturally emerges from the analysis of the spectra of Gamma-Ray
Bursts (GRBs). These results, made possible by the recently obtained analytic
expressions of the equitemporal surfaces in the GRB afterglow, depend crucially
on the single parameter R describing the effective area of the fireball
emitting the X- and gamma ray radiation. The X- and gamma ray components of the
afterglow radiation are shown to have a thermal spectrum in the co-moving frame
of the fireball and originate from a stable shock front described
self-consistently by the Rankine-Hugoniot equations. Precise predictions are
presented on a correlations between spectral changes and intensity variations
in the prompt radiation verifiable, e.g., by the Swift and future missions. The
highly variable optical and radio emission depends instead on the parameters of
the surrounding medium. The GRB 991216 is used as a prototype for this model.Comment: 9 pages, 3 figures, to appear on International Journal of Modern
Physics
Dependence of galaxy clustering on UV-luminosity and stellar mass at
We investigate the dependence of galaxy clustering at on
UV-luminosity and stellar mass. Our sample consists of 10,000
Lyman-break galaxies (LBGs) in the XDF and CANDELS fields. As part of our
analysis, the relation is estimated for the sample,
which is found to have a nearly linear slope of . We subsequently measure the angular correlation function and
bias in different stellar mass and luminosity bins. We focus on comparing the
clustering dependence on these two properties. While UV-luminosity is only
related to recent starbursts of a galaxy, stellar mass reflects the integrated
build-up of the whole star formation history, which should make it more tightly
correlated with halo mass. Hence, the clustering segregation with stellar mass
is expected to be larger than with luminosity. However, our measurements
suggest that the segregation with luminosity is larger with
confidence (neglecting contributions from systematic errors). We compare this
unexpected result with predictions from the \textsc{Meraxes} semi-analytic
galaxy formation model. Interestingly, the model reproduces the observed
angular correlation functions, and also suggests stronger clustering
segregation with luminosity. The comparison between our observations and the
model provides evidence of multiple halo occupation in the small scale
clustering.Comment: 10 pages, 6 figures, 2 tables, accepted for publication in MNRA
The Luminosity Function at z~8 from 97 Y-band dropouts: Inferences About Reionization
[Abbreviated] We present the largest search to date for Lyman break
galaxies (LBGs) based on 350 arcmin of HST observations in the V-, Y-, J-
and H-bands from the Brightest of Reionizing Galaxies (BoRG) survey. The BoRG
dataset includes 50 arcmin of new data and deeper observations of two
previous BoRG pointings, from which we present 9 new LBG candidates,
bringing the total number of BoRG LBGs to 38 with (AB system). We introduce a new Bayesian formalism for
estimating the galaxy luminosity function (LF), which does not require binning
(and thus smearing) of the data and includes a likelihood based on the formally
correct binomial distribution as opposed to the often used approximate Poisson
distribution. We demonstrate the utility of the new method on a sample of
LBGs that combines the bright BoRG galaxies with the fainter sources published
in Bouwens et al. (2012) from the HUDF and ERS programs. We show that the
LF is well described by a Schechter function with a characteristic
magnitude , a faint-end slope of , and a number density of . Integrated down to this
LF yields a luminosity density, . Our LF analysis
is consistent with previously published determinations within 1. We
discuss the implication of our study for the physics of reionization. By
assuming theoretically motivated priors on the clumping factor and the photon
escape fraction we show that the UV LF from galaxy samples down to
can ionize only 10-50% of the neutral hydrogen at . Full reionization
would require extending the LF down to .Comment: Accepted for publication in ApJ, 22 pages, 15 figure
- âŠ