Asymptotic cosmological solutions for string/brane gases with solitonic fluxes

We present new cosmological solutions for brane gases with solitonic fluxes that can dynamically explain the existence of three large spatial dimensions. This reasserts the importance of fluxes for understanding the full space of solutions in a potential implementation of the Brandenberger-Vafa mechanism with M2-branes. Additionally, we study a particular example in which the cosmological dynamics supported by a string gas with a NS flux in the ten-dimensional dilaton gravity framework is asymptotically equivalent to that of a M2-brane gas with a certain wrapping configuration in eleven-dimensional supergravity. We speculate that this connection between the ten- and eleven-dimensional implementations of the Brandenberger-Vafa mechanism could be a general feature.Comment: 9 pages, 2 figures, revtex

The challenge of high capital inflows to financial stability: an emerging market perspective.

High liquidity and continued economic weakness in advanced economies have led to a surge in capital flows to emerging markets with strong fundamentals and open financial accounts such as Brazil. While capital inflows have undeniable benefits to emerging economies, they are also potentially destabilising. Past experience has shown that high levels of capital inflows can lead to exchange rate volatility and credit or asset price bubbles. In the context of Brazil’s inflation-targeting regime for monetary policy, macroprudential measures have proved to be a useful complement to traditional macroeconomic policies. However, today’s imbalanced global economy presents an especially difficult challenge for policymakers. The international financial community needs to work together on two fronts: improving our macroprudential toolkit and building a stronger framework for multilateral macroeconomic cooperation.

Study of the order of the phase transition in pure U(1) gauge theory with Villain action

We address the question of the order of the deconfinement phase transition of four dimensional U(1) lattice gauge theory. Simulations of the Z-gauge theory dual to the Villain action on toroidal lattices up to lattice sizes of 28^4 give results consistent with both, a vanishing and a nonvanishing discontinuity in the thermodynamic limit. A decision on the order of the phase transition requires still larger lattice sizes.Comment: LATTICE98(gauge), 3 pages, 2 figure

APPLICATION OF THE TRANSHIPMENT MODEL TO DEVELOPMENT OF THE SEED INDUSTRY IN NORTHEAST BRAZIL

Crop Production/Industries,

On Pruning for Score-Based Bayesian Network Structure Learning

Many algorithms for score-based Bayesian network structure learning (BNSL), in particular exact ones, take as input a collection of potentially optimal parent sets for each variable in the data. Constructing such collections naively is computationally intensive since the number of parent sets grows exponentially with the number of variables. Thus, pruning techniques are not only desirable but essential. While good pruning rules exist for the Bayesian Information Criterion (BIC), current results for the Bayesian Dirichlet equivalent uniform (BDeu) score reduce the search space very modestly, hampering the use of the (often preferred) BDeu. We derive new non-trivial theoretical upper bounds for the BDeu score that considerably improve on the state-of-the-art. Since the new bounds are mathematically proven to be tighter than previous ones and at little extra computational cost, they are a promising addition to BNSL methods

Simplified model for the non-linear behaviour representation of reinforced concrete columns under biaxial bending

In the present paper a simplified model is proposed for the force-deformation behaviour of reinforced concrete members under biaxial loading combined with axial force. The starting point for the model development was an existing fixed-length plastic hinge element model that accounts for the non-linear hysteretic behaviour at the element end-sections, characterized by trilinear moment-curvature laws. To take into account the section biaxial behaviour, the existing model was adopted for both orthogonal lateral directions and an interaction function was introduced to couple the hysteretic response of both directions. To calibrate the interaction function it were used numerical results, obtained from fibre models, and experimental results. For the parameters identification, non-linear optimization approaches were adopted, namely: the gradient based methods followed by the genetic, evolutionary and nature-inspired algorithms. Finally, the simplified non-linear model proposed is validated through the analytical simulation of biaxial test results carried out in full-scale reinforced concrete columns

The political economy of formal sector pay and employment in developing countries

Domestic labor market outcomes influence the direction and magnitude of the flow of international migration. When wages are low and jobs are scarce, workers tend to migrate to environments where jobs are available at higher wages. But as labor demand grows, a labor-exporting country may become a net labor importer. Such a"migration transition"- already much in evidence in East and Southeast Asian countries and beginning for skilled workers in India - is analogous to the demographic transition. The process of political economy described by the authors affects the level and growth of wages and of formal sector emmployment. So it is important for policymakers concerned about migration to high-income countries to take it into account. An efficient, flexible, responsive labormarket contributes to growth by creating an appropriate economic environment. In this respect, labor policy is like macroeconomic and trade policy. Unlike the accumulation of physical and human capital and technical progress, a well-functioning labor market is not itself a source of economic growth. Yet labor market pathologies, like macroeconomic mismanagement, can be extremely costly, severely constraining growth of output and employment and increasing inequality. Similarly, failure to adequately address the labor-market aspects of policy reform can result in the failure of other dimensions of reform. The smooth functioning of the labor market feeds on itself, enhancing the credibility of both workers and the elite. Conversely, poor labor market performance can also be self-reinforcing. Attempts to reform the labor market feeds on itself, enhancing the credibility of both workers and the elite. The payoff on labor reform can be high for both groups. The challenge is to find mechanisms whereby the credibility of both groups can be bolstered.Labor Policies,Environmental Economics&Policies,Banks&Banking Reform,Municipal Financial Management,Health Economics&Finance,Environmental Economics&Policies,Banks&Banking Reform,Municipal Financial Management,Health Economics&Finance,Labor Standards

Heterotrophy as a tool to overcome the long and costly autotrophic scale-up process for large scale production of microalgae

Industrial scale-up of microalgal cultures is often a protracted step prone to culture collapse and the occurrence of unwanted contaminants. To solve this problem, a two-stage scale-up process was developed - heterotrophically Chlorella vulgaris cells grown in fermenters (1st stage) were used to directly inoculate an outdoor industrial autotrophic microalgal production unit (2nd stage). A preliminary pilot-scale trial revealed that C. vulgaris cells grown heterotrophically adapted readily to outdoor autotrophic growth conditions (1-m3 photobioreactors) without any measurable difference as compared to conventional autotrophic inocula. Biomass concentration of 174.5 g L-1, the highest value ever reported for this microalga, was achieved in a 5-L fermenter during scale-up using the heterotrophic route. Inocula grown in 0.2- and 5-m3 industrial fermenters with mean productivity of 27.54 ± 5.07 and 31.86 ± 2.87 g L-1 d-1, respectively, were later used to seed several outdoor 100-m3 tubular photobioreactors. Overall, all photobioreactor cultures seeded from the heterotrophic route reached standard protein and chlorophyll contents of 52.18 ± 1.30% of DW and 23.98 ± 1.57 mg g-1 DW, respectively. In addition to providing reproducible, high-quality inocula, this two-stage approach led to a 5-fold and 12-fold decrease in scale-up time and occupancy area used for industrial scale-up, respectively.Agência financiadora project FERMALG 017608 Fundacao para a Ciencia e a Tecnologia (FCT) UID/Multi/04326/2019 project FERMALG (AVISO) 32/SI/2015info:eu-repo/semantics/publishedVersio

Universality of the gauge-ball spectrum of the four-dimensional pure U(1) gauge theory

We continue numerical studies of the spectrum of the pure U(1) lattice gauge theory in the confinement phase, initiated in our previous work. Using the extended Wilson action $S = -\sum_P [\beta \cos(\Theta_P) + \gamma \cos(2\Theta_P)]$ we address the question of universality of the phase transition line in the ($\beta,\gamma$) plane between the confinement and the Coulomb phases. Our present results at $\gamma= -0.5$ for the gauge-ball spectrum are fully consistent with the previous results obtained at $\gamma= -0.2$. Again, two different correlation length exponents, $\nu_{ng} = 0.35(3)$ and $\nu_{g} = 0.49(7)$, are obtained in different channels. We also confirm the stability of the values of these exponents with respect to the variation of the distance from the critical point at which they are determined. These results further demonstrate universal critical behaviour of the model at least up to correlation lengths of 4 lattice spacings when the phase transition is approached in some interval at $\gamma\leq -0.2$.Comment: 16 page