Gravitational wave recoils in non-axisymmetric Robinson-Trautman spacetimes

We examine the gravitational wave recoil waves and the associated net kick velocities in non-axisymmetric Robinson-Trautman spacetimes. We use characteristic initial data for the dynamics corresponding to non-head-on collisions of black holes. We make a parameter study of the kick distributions, corresponding to an extended range of the incidence angle $\rho_0$ in the initial data. For the range of $\rho_0$ examined ($3^{\circ} \leq \rho_0 \leq 110^{\circ}$) the kick distributions as a function of the symmetric mass parameter $\eta$ satisfy a law obtained from an empirical modification of the Fitchett law, with a parameter $C$ that accounts for the non-zero net gravitational momentum wave fluxes for the equal mass case. The law fits accurately the kick distributions for the range of $\rho_0$ examined, with a rms normalized error of the order of $5 \%$. For the equal mass case the nonzero net gravitational wave momentum flux increases as $\rho_0$ increases, up to $\rho_0 \simeq 55^{\circ}$ beyond which it decreases. The maximum net kick velocity is about $190 {\rm km/s}$ for for the boost parameter considered. For $\rho_0 \geq 50^{\circ}$ the distribution is a monotonous function of $\eta$. The angular patterns of the gravitational waves emitted are examined. Our analysis includes the two polarization modes present in wave zone curvature.Comment: 10 pages, 5 figures. arXiv admin note: substantial text overlap with arXiv:1403.4581, arXiv:1202.1271, arXiv:1111.122

Harmful effects of metal(loid) oxide nanoparticles

The incorporation of nanomaterials (NMs), including metal(loid) oxide (MOx) nanoparticles (NPs), in the most diversified consumer products, has grown enormously in recent decades. Consequently, the contact between humans and these materials increased, as well as their presence in the environment. This fact has raised concerns and uncertainties about the possible risks of NMs to human health and the adverse effects on the environment. These concerns underline the need and importance of assessing its nanosecurity. The present review focuses on the main mechanisms underlying the MOx NPs toxicity, illustrated with different biological models: release of toxic ions, cellular uptake of NPs, oxidative stress, shading effect on photosynthetic microorganisms, physical restrain and damage of cell wall. Additionally, the biological models used to evaluate the potential hazardous of nanomaterials are briefly presented, with particular emphasis on the yeast Saccharomyces cerevisiae, as an alternative model in nanotoxicology. An overview containing recent scientific advances on cellular responses (toxic symptoms exhibited by yeasts) resulting from the interaction with MOx NPs (inhibition of cell proliferation, cell wall damage, alteration of function and morphology of organelles, presence of oxidative stress bio-indicators, gene expression changes, genotoxicity and cell dead) is critically presented. The elucidation of the toxic modes of action of MOx NPs in yeast cells can be very useful in providing additional clues about the impact of NPs on the physiology and metabolism of the eukaryotic cell. Current and future trends of MOx NPs toxicity, regarding their possible impacts on the environment and human health, are discussed.This work was supported by National funds through FCT - Foundation for Science and Technology under the scope of the projects UIDB/50006/2020, UID/BIO/04469/2020 unit and BioTecNorte opera tion (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio

The development impact of the illegality of drug trade

This paper reviews the unintended consequences of the war on drugs, particularly for developing countries, and weighs them against the evidence regarding the efficacy of prohibition to curb drug use and trade. It reviews the available evidence and presents new results that indicate that prohibition has limited effects on drug prevalence and prices, most likely indicating a combination of inelastic drug demand (due to its addictive properties) and elastic supply responses (due to black markets). This should turn the focus to the unintended consequences of drug prohibition. First, the large demand for drugs, particularly in developed countries, generates the possibility of massive profits to potential drug providers. This leads to the formation of organized crime groups, which use violence and corruption as their means of survival and expansion and which, in severe cases, challenge the state and seriously compromise public stability and safety. Second, prohibition and its derived illegal market impose greater costs on farmers than on drug traffickers. In many instances, this entails the transfer of wealth from poor peasants to rich (and ruthless) traders. Third, criminalization can exacerbate the net health effects of drug use. These consequences are so pernicious that they call for a fundamental review of drug policy around the world.Health Monitoring&Evaluation,Crime and Society,Economic Theory&Research,Post Conflict Reconstruction,Markets and Market Access

Using a flocculent brewer’s yeast strain of Saccharomyces cerevisiae in the removal of heavy metals

Fundação para a Ciência e a Tecnologia (FCT) - POCTI/CTA/47875/2002, (SFRH/BD/31755/2006)Fundo Europeu de Desenvolvimento Regional (FEDER

Removal of heavy metals using cells of Saccharomyces cerevisiae as a green technology

Anthropogenic activities are largely responsible for the release of heavy metals in the environment. Unlike organic pollutants, heavy metals are not degraded and remain indefinitely in the ecosystem, which poses a different kind of challenge for remediation. Municipal sanitary sewers are not designed to treat toxic wastes, such as industrial effluents containing heavy metals. Thus, heavy metals should be removed in a “previous step”, from these metalladen effluents before they are released into the water body or sent to a municipal treatment plant. Conventional physicochemical technologies are not environmental friendly, fully efficient or present very high costs when applied to large volume of wastewaters containing low metal concentration (1- 100 mg/l). The disadvantages of these available “best treatment technologies”, associated with the increase of environmental regulations, have compelled the search for alternative, low-cost and efficient processes for the detoxification of metal-bearing wastewaters. The advantages and the current knowledge of the mechanisms of metal removal by yeast cells of Saccharomyces cerevisiae will be presented. The use of live or dead biomass and the influence of biomass inactivation processes or the modification of the yeast surface on the metal accumulation characteristics will be outlined. The importance of the physico-chemical characteristics of the effluents and the role of chemical speciation as a tool for predicting and optimising metal removal will be highlighted. The use of yeast cells as the only treatment process of real effluents or in a “polishing” step, after the chemical treatment of the raw effluent to remove the bulk of the metal will be presented. The problem of biomass separation, after treatment of the effluents, and the use of flocculent characteristics of yeast cells, as an alternative process of cell-liquid separation, will also be discussed. The convenient management of the contaminated biomass and the advantages of the selective recovery of heavy metals in the development of a closed cycle without residues (green technology) will be presented