Relating black holes in two and three dimensions

The three dimensional black hole solutions of Ba\~nados, Teitelboim and Zanelli (BTZ) are dimensionally reduced in various different ways. Solutions are obtained to the Jackiw-Teitelboim theory of two dimensional gravity for spinless BTZ black holes, and to a simple extension with a non-zero dilaton potential for black holes of fixed spin. Similar reductions are given for charged black holes. The resulting two dimensional solutions are themselves black holes, and are appropriate for investigating exact ``S-wave'' scattering in the BTZ metrics. Using a different dimensional reduction to the string inspired model of two dimensional gravity, the BTZ solutions are related to the familiar two dimensional black hole and the linear dilaton vacuum.Comment: 12 pages, CTP #2181, January 199

Accessing the Influence of Hess-Murray Law on Suspension Flow through Ramified Structures

The present study focuses on fluid flow and particle transport in symmetric T-shaped structures formed by tubes with circular and square cross-section. The performances of optimized structures (i.e., structures designed based on constructal allometric laws for minimum flow resistance) and not optimized structures were studied. Flow resistance and particle penetration efficiency were studied both for laminar and turbulent flow regimes, and for micrometer and submicrometer particles. Optimized structures have been proven to perform better for fluid flow but they have a similar performance for particle transport

Honey volatiles as a fingerprint for botanical origin: a review on their occurrence on monofloral honeys

Honeys have specific organoleptic characteristics, with nutritional and health benefits, being highly appreciated by consumers, not only in food but also in the pharmaceutical and cosmetic industries. Honey composition varies between regions according to the surrounding flora, enabling its characterization by source or type. Monofloral honeys may reach higher market values than multifloral ones. Honey's aroma is very specific, resulting from the combination of volatile compounds present in low concentrations. The authentication of honey's complex matrix, according to its botanical and/or geographical origin, represents a challenge nowadays, due to the different sorts of adulteration that may occur, leading to the search for reliable marker compounds for the different monofloral honeys. The existing information on the volatiles of monofloral honeys is scarce and disperse. In this review, twenty monofloral honeys and honeydews, from acacia, buckwheat, chestnut, clover, cotton, dandelion, eucalyptus, fir tree, heather, lavender, lime tree, orange, pine, rape, raspberry, rhododendron, rosemary, strawberry tree, sunflower and thyme, were selected for volatile comparison purposes. Taking into consideration the country of origin, the technique of isolation and analysis, the five main volatiles from each of the honeys are compared. Whereas some compounds were found in several types of monofloral honey, and thus not considered good volatile markers, some monofloral honeys revealed characteristic volatile compounds independently of their provenance.Funding: SFRH/BD/117013/2016, UID/AGR/00690/2019, UID/AMB/50017/2019, MED (UIDB/05183/2020), FEDER, PT2020 PACompete 2020info:eu-repo/semantics/publishedVersio

The provision of wage insurance by the firm: evidence from a longitudinal matched employer-employee dataset

We evaluate the impact of product market uncertainty on workers wages, addressing the questions: To what extent do firms provide insurance to their workforce, insulating their wages from shocks in product markets? How does the amount of insurance provided vary with firm and worker attributes? We use a longitudinal matched employer-employee dataset of remarkable quality. The empirical strategy is based on Guiso et al. (2005). We first estimate dynamic models of sales and wages to retrieve consistent estimates of shocks to firms’ sales and to workers’ earnings. We are then able to estimate the sensitivity of wages to permanent and transitory shocks to firm performance. Results point to the rejection of the full insurance hypothesis. Workers’ wages respond to permanent shocks to firm performance, whereas they are not sensitive to transitory shocks. Managers are not fully insured against transitory shocks, while they receive the same protection against permanent shocks as workers in other occupations. Firms with higher variability in their sales, and those operating in di?erent industries, o?er more insurance against permanent shocks. Comparison with Guiso et al. (2005) indicates that Portuguese firms provide less insurance than Italian firms, corroborating evidence on the high degree of wage flexibility in Portugal.

Assessing welfare impacts of some debt-consolidation episodes in the European Union

This paper aims at characterizing debt consolidation processes put forward by some European countries in order to assess welfare and, in particular, the inequality effects involved. For that we built a general equilibrium heterogeneous-agent model capable of exploring the relationship between fiscal policy variables and the endogenous crosssection distribution of income and wealth. Results show that, with the exception of the Belgian case, all consolidation strategies entail positive welfare gains. The transition costs affect all episodes and are determinant in sorting among the welfareenhancing strategies. Our results confirm the superiority of the adjustments based on unproductive expenditures over those based on tax increases or social transfer reductions. Finally, all strategies involve lower welfare inequality costs.fiscal consolidation dynamics, European Union, heterogeneous agent model, inequality, welfare.

Welfare-improving Government Behaviour and Inequality - Inspection Using a Heterogeneous-agent Model

Governments behavior is expected to be non-neutral in terms of impacts on both welfare and inequality. In spite of their multivariate form, a tentative assessment of such inequality impacts can be provided by using a general equilibrium model with heterogeneous-agents and where wealth and income distribution is determined endogenously. Using a model capable of exploring the relationship between fiscal policy variables and the endogenous cross-section distribution of income, wealth, consumption and leisure, this paper produces a welfare and inequality analysis of several equilibriums resulting from different combinations of debt levels and of government budget variables. Moreover, such assessment is based on the empirical reality of the EU countries.government budget composition and debt, heterogeneous agent model, idiosyncratic shock, inequality, welfare.

Market Impact of International Sporting and Cultural Events

This paper investigates the impact of international sporting and cultural events on national stock markets. We study market reaction to the announcements of the selected country hosting the Summer and Winter Olympic Games, the World Football Cup, the European Football Cup and World and Specialized Exhibitions. We also measure the market effects of the announcement of the nomination of the European Cultural City. First, we evaluate the abnormal returns of winning bidders at (and around) the announcement date using an event study methodology. We study the impact at market and industry-levels. Second, we analyze the determinants of the variation in abnormal returns across events and industries on the basis of a set of variables found important by previous studies and control for the prior probability of observing the event. Third, on the basis of a simple model of partial anticipation, we reexamine the abnormal returns observed for the winning and losing countries and perform a series of tests to disentangle the different theoretical arguments that could account for the observed stock market behavior. Our initial results suggest that the abnormal returns measured at the announcement date and around the event are not consistently different from zero. Further, when we look at particular industries, we find no evidence supporting that industries, that a priori were more likely to extract direct benefits from the event, observe positive significant effects. Yet when we control for the prior expectations, the announcement of these mega-events is associated with a positive market reaction in the nominated country and a negative reaction in the losing country. Overall we interpret our findings as supportive of rational asset pricing and partial anticipation.Market efficiency; Event studies; Mega-events

Market Impact of International Sporting and Cultural Events

This paper investigates the impact of international sporting and cultural events on national stock markets. We study market reaction to the announcements of the selected country hosting mega-events such as the Olympic Games, the World and the European Football Cups and World Exhibitions. First, we evaluate the abnormal returns of winning bidders at (and around) the announcement date at market and industry-levels. Second, we analyze the determinants of the variation in abnormal returns across events and industries and control for the prior probability of observing the event. Third, on the basis of a simple model of partial anticipation, we reexamine the abnormal returns observed for the winning and losing countries. Our initial results suggest that the abnormal returns are not consistently different from zero. Further, when we look at particular industries, we find no evidence supporting that industries, that a priori were more likely to extract direct benefits from the event, observe positive significant effects. Yet when we control for the prior expectations, the announcement of these megaevents is associated with a positive stock market reaction in the nominated country and a negative reaction in the losing country. Overall we interpret our findings as supportive of rational asset pricing and partial anticipation.Market efficiency; Event studies; Mega-events

Phase only transmit beamforming for spectrum sharing microwave systems

This paper deals with the problem of phase-only transmit beamforming in spectrum sharing microwave systems. In contrast to sub-6 GHz schemes, general microwave systems require a large number of antennas due to its huge path loss. As a consequence, digital beamforming needs a large number of computational resources compared to analog beamforming, which only needs a single radio-frequency chain, results the less computational demanding solution. Analog schemes are usually composed by a phase shifter network whose elements transmit at a certain fixed power so that the system designer shall compute the phase values for each element given a set of directions. This approach leads to non-convex quadratic problems where the traditional semidefinite relaxation fails to deliver satisfactory outcomes. In order to solve this, we propose a nonsmooth method that behaves well in several scenarios. Numerical evaluations in different spectrum sharing scenarios, which show the performance of our method, are provided.Peer ReviewedPostprint (author's final draft

The Impacts of Structural Changes in the Labor Market: a Comparative Statics Analysis Using Heterogeneous-agent Framework

In this paper we aim at analyzing the impacts on welfare and wealth and consumption distribution across different labor market structural features. In particular, we pursue a steady-state analysis to assess the impacts of unit vacancy costs, unemployment replacement ratio or the job destruction rate, when they are changed in order to promote a given reduction in the unemployment rate. We combine a labor market search and matching framework with unions, based on Mortensen and Pissarides (1994) with a heterogeneous-agent framework close to Imrohoroglu (1989) in a closed economy model. Such approach enables the joint assessment of macroeconomic welfare and inequality together with implications derived from institutional changes in labor market. Moreover, the transition matrix between worker's states is endogenous, fully derived from labor market conditions. Using feasible calibration to the Euro Area, we conclude that different institutional changes to promote unemployment reduction have non-neutral and differentiated effects on welfare and inequality. While changing unit vacancy costs and job destruction can be ranked, changes in the unemployment benefit replacement ration involve a trade-off between gains in welfare and in consumption/income distribution.Labor market institutions, search and matching models, heterogeneous-agent models, welfare and inequality.