Flow of a blood analogue solution through microfabricated hyperbolic contractions

The flow of a blood analogue solution past a microfabricated hyperbolic contraction followed by an abrupt expansion was investigated experimentally. The shape of the contraction was designed in order to impose a nearly constant strain rate to the fluid along the centerline of the microgeometry. The flow patterns of the blood analogue solution and of a Newtonian reference fluid (deionized water), captured using streak line imaging, are quite distinct and illustrate the complex behavior of the blood analogue solution flowing through the microgeometry. The flow of the blood analogue solution shows elastic-driven effects with vortical structures emerging upstream of the contraction, which are absent in Newtonian fluid flow. In both cases the flow also develops instabilities downstream of the expansion but these are inertia driven. Therefore, for the blood analogue solution at high flow rates the competing effects of inertia and elasticity lead to complex flow patterns and unstable flow develops

The political economy of public spending composition: evidence from a panel of OECD countries

We evaluate the influence of political and institutional features in public spending and its functional composition, by focussing on political actors’ preferences, both opportunistic and partisan, as well as on institutional arrangements as political fragmentation, the electoral system and the political regime. We use a dataset covering 23 OECD countries from 1970 to 2004. Empirical evidence supports the opportunistic approach in the sense that governments tend to engage in fiscal policy manipulation in order to win the next parliamentary election. This pre-electoral manipulation seems to be stronger in new democracies and under center and left-wing governments. There is, however, no evidence of pure partisan behavior. Furthermore, political fragmentation, with regard to both the government and the parliament, seems to favor fiscal indiscipline, particularly on social items.public spending; functional composition; political economy

A conditional compression distance that unveils insights of the genomic evolution

We describe a compression-based distance for genomic sequences. Instead of using the usual conjoint information content, as in the classical Normalized Compression Distance (NCD), it uses the conditional information content. To compute this Normalized Conditional Compression Distance (NCCD), we need a normal conditional compressor, that we built using a mixture of static and dynamic finite-context models. Using this approach, we measured chromosomal distances between Hominidae primates and also between Muroidea (rat and mouse), observing several insights of evolution that so far have not been reported in the literature.Comment: Full version of DCC 2014 paper "A conditional compression distance that unveils insights of the genomic evolution

Asymmetric information and exchange of information about product differentiation

We introduce asymmetric information about consumers' transportation costs (i.e., the degree of product differentiation) in the model of Hotelling (1929). When the transportation costs are high, both firms have lower profits than in the case of perfect information. Contrarily, both firms may prefer the asymmetric information case if the transportation costs are low (the informed firm always prefers the informational advantage, while the uninformed firm may or may not prefer to remain uninformed). Information sharing is ex-ante advantageous for the firms, but ex-post damaging in the case of low transportation costs. If the information is not verifiable, the informed firm always tends to announce that the transportation cost is high. To induce truthful revelation: (i) the uninformed firm must pay for the informed firm to confess that the transportation costs are low; and (ii) the informed firm must make a payment (to the uninformed firm or to a third party) for the uninformed firm to believe that the transportation costs are high.Hotelling model; Horizontal differentiation; Asymmetric information; Transportation costs; Information sharing

Hedging with CO2 allowances: the ECX market

We investigate and empirically estimate optimal hedge ratios, for the first time, in the EU ETS carbon market. Minimum variance hedge ratios are conditionally estimated with multivariate GARCH models, and unconditionally by OLS and the naïve strategy for the European Climate Exchange (ECX) market in the period 2005-2009. Also, utility gains are considered in order to take into account risk-return considerations. Empirical results indicate that dynamic hedging provides superior gains (in reducing the variance portfolio) compared to those obtained from static hedging, when adjustment costs are not taken into account. Moreover, results improve when the leptokurtic characteristics of the data are into consideration through distributions. Results are always compared in and out of sample, suggesting also that utility gains increase with investor's increased preference over risk.CO2 Emission Allowances; Dynamic Hedging; Futures Prices; Risk Management; Spot Prices

CO2 spot and futures price analysis for EEX and ECX

In this work we analyze, explore and measure two of the most important concepts for the theory of storable commodity markets. After analyzing the statistical properties of spot and futures EU ETS allowances for Germany and France, we model and test the risk premium and convenience yield for CO2 contracts accordingly to previous economic theories, for the period 2005-2009. Results indicate that convenience yields are positively related to the spot CO2 return while being negatively influenced by the spot volatility. This negative impact of spot volatility is also verified for the risk premium, with the latter varying positively with time to maturity. Contradicting previous empirical findings, we found only a positive influence of the convenience yield on the risk premium for the ECX French market and for Phase II contracts, leading us to conclude that results are Phase, market and data span dependent. Moreover, results are independent on the volatility forecast used and important for risk management purposes for allowances markets participants. Moreover, day-ahead markets for CO2 are in "normal contango" for the entire data period under analysis, contrary to previous empirical findings for the allowances market.CO2 Emission Allowances; Volatility; Volume; Maturity; Convenience Yield; Risk Premium; Spot Prices; Futures Prices

Divergent streamlines and free vortices in Newtonian fluid flows in microfluidic flow focusing devices

The appearance of divergent streamlines and subsequent formation of free vortices in Newtonian fluid flows through microfluidic flow-focusing geometries is discussed in this work. The micro-geometries are shaped like a cross-slot but comprise three entrances and one exit. The divergent flow and subsequent symmetric vortical structures arising near the centreline of the main inlet channel are promoted even under creeping flow conditions, and are observed experimentally and predicted numerically above a critical value of the ratio of inlet velocities (VR). As VR is further increased these free vortices continue to grow until a maximum size is reached due to geometrical constraints. The numerical calculations are in good agreement with the experimental observations and we probe numerically the effects of the geometric parameters and of inertia on the flow patterns. In particular, we observe that the appearance of the central recirculations depends non-monotonically on the relative width of the entrance branches and we show that inertia enhances the appearance of the free vortices. On the contrary, the presence of the walls in three-dimensional geometries has a stabilizing effect for low Reynolds numbers, delaying the onset of these secondary flows to higher VR. The linearity of the governing equations for creeping flow of Newtonian fluids was invoked to determine the flow field for any VR as a linear combination of the results of three other independent solutions in the same geometry

Antibiotic consumption in Portugal: 2010 and 2011

The use of antibiotics has contributed to a marked decrease in morbidity caused by communicable and infec- tious diseases over the past few years. The aim of our study is to evaluate the use of antibiotics in clinic in 2010 and 2011, considering two different methodologies: the defined daily dose per 1000 inhabitants per day (DHD) and the number of packages per 1000 inhabitants per day (PHD)