333 research outputs found
A new convergent algorithm to approximate potentials from fixed angle scattering data
We introduce a new iterative method to recover a real compact supported
potential of the Schr\"odinger operator from their fixed angle scattering data.
The method combines a fixed point argument with a suitable approximation of the
resolvent of the Schr\"odinger operator by partial sums associated to its Born
series. Convergence is established for potentials with small norm in certain
Sobolev spaces. As an application we show some numerical experiments that
illustrate this convergence.Comment: 25 pages, 6 figure
Diavideos: a Diabetes Health Video Portal
Diavideos1 is a web platform that collects trustworthy
diabetes health videos from YouTube and offers them in a easy
way. YouTube is a big repository of health videos, but good
content is sometimes mixed with misleading and harmful
videos such as promoting anorexia [1].Diavideos is a web
portal that provides easy access to a repository of trustworthy
diabetes videos. This poster describes Diavideos and explains
the crawling method used to retrieve these videos from trusted
channels
A methodology to improve simulation of multibody systems using estimation techniques
This paper presents a methodology for state estimation and accuracy improvement of computer simulations of computer aided engineering (CAE) models based on prediction and correction state estimation techniques and sensing. The aim is to simulate the dynamic behaviour of a real system, which can be sensed, and obtain values of states that are not measurable due to economic or technical limitations. This methodology can be applied to both optimization of design processes and on-line control of complex systems. State estimation techniques are currently used only on mathematical models, where the relationships among system variables are expressed by means of mathematical language, making state observer implementation possible but leading to limitations in system modelling and knowledge. Favoured over mathematical models, multibody CAE models (created by means of computer-aided engineering software) have become the essential tool for complex system development, simulation, analysis, optimization and control, such as multibody systems; one of their main advantages is the ease and flexibility in creating and modifying them, allowing the faithful modelling of complex systems
Impact assessment of interregional government transfers in Brazil: an input-output approach
Redistributive policies carried out by the central government through interregional government transfers is a relevant feature of the Brazilian federal fiscal system. Regional shares of the central government revenues in the poorer regions have been recurrently smaller than the shares of central government expenditures in those regions. Appeal to core-periphery outcomes could be made, as São Paulo, the wealthiest state in the country, concentrated, in 2005, over 40% of total Federal tax revenue, receiving less than 35% of Federal expenditures. These figures suggest a redistribution of public funds from the spatial economic core of the economy to the peripheral areas. This paper investigates the role interregional transfers play in the redistribution of activities in the country, using an interregional input-output approach. Counterfactual simulations allow us to estimate some costs and benefits, for the core and periphery respectively, from such fiscal mechanisms.Interregional government transfers, input-output analysis, impact analysis, Brazilian economy
La enseñanza de la filosofía en la Universidad de Córdoba durante los último años de la dominación española
Fil: Luque Colombres, Carlos A..
Universidad Nacional de Córdob
Geometrically motivated hyperbolic coordinate conditions for numerical relativity: Analysis, issues and implementations
We study the implications of adopting hyperbolic driver coordinate conditions
motivated by geometrical considerations. In particular, conditions that
minimize the rate of change of the metric variables. We analyze the properties
of the resulting system of equations and their effect when implementing
excision techniques. We find that commonly used coordinate conditions lead to a
characteristic structure at the excision surface where some modes are not of
outflow-type with respect to any excision boundary chosen inside the horizon.
Thus, boundary conditions are required for these modes. Unfortunately, the
specification of these conditions is a delicate issue as the outflow modes
involve both gauge and main variables. As an alternative to these driver
equations, we examine conditions derived from extremizing a scalar constructed
from Killing's equation and present specific numerical examples.Comment: 9 figure
Capsid Structure of dsRNA Fungal Viruses
Most fungal, double-stranded (ds) RNA viruses lack an extracellular life cycle stage and are transmitted by cytoplasmic interchange. dsRNA mycovirus capsids are based on a 120-subunit T = 1 capsid, with a dimer as the asymmetric unit. These capsids, which remain structurally undisturbed throughout the viral cycle, nevertheless, are dynamic particles involved in the organization of the viral genome and the viral polymerase necessary for RNA synthesis. The atomic structure of the T = 1 capsids of four mycoviruses was resolved: the L-A virus of Saccharomyces cerevisiae (ScV-L-A), Penicillium chrysogenum virus (PcV), Penicillium stoloniferum virus F (PsV-F), and Rosellinia necatrix quadrivirus 1 (RnQV1). These capsids show structural variations of the same framework, with 60 asymmetric or symmetric homodimers for ScV-L-A and PsV-F, respectively, monomers with a duplicated similar domain for PcV, and heterodimers of two different proteins for RnQV1. Mycovirus capsid proteins (CP) share a conserved α-helical domain, although the latter may carry different peptides inserted at preferential hotspots. Insertions in the CP outer surface are likely associated with enzymatic activities. Within the capsid, fungal dsRNA viruses show a low degree of genome compaction compared to reoviruses, and contain one to two copies of the RNA-polymerase complex per virion
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