First principles simulations of direct coexistence of solid and liquid aluminium

First principles calculations based on density functional theory, with generalised gradient corrections and ultrasoft pseudopotentials, have been used to simulate solid and liquid aluminium in direct coexistence at zero pressure. Simulations have been carried out on systems containing up to 1000 atoms for 15 ps. The points on the melting curve extracted from these simulations are in very good agreement with previous calculations, which employed the same electronic structure method but used an approach based on the explicit calculation of free energies [L. Vo\v{c}adlo and D. Alf\`e, Phys. Rev. B, {\bf 65}, 214105 (2002).]Comment: To appear in Phys. Rev.

Test of a theoretical equation of state for elemental solids and liquids

We propose a means for constructing highly accurate equations of state (EOS) for elemental solids and liquids essentially from first principles, based upon a particular decomposition of the underlying condensed matter Hamiltonian for the nuclei and electrons. We also point out that at low pressures the neglect of anharmonic and electron-phonon terms, both contained in this formalism, results in errors of less than 5% in the thermal parts of the thermodynamic functions. Then we explicitly display the forms of the remaining terms in the EOS, commenting on the use of experiment and electronic structure theory to evaluate them. We also construct an EOS for Aluminum and compare the resulting Hugoniot with data up to 5 Mbar, both to illustrate our method and to see whether the approximation of neglecting anharmonicity et al. remains viable to such high pressures. We find a level of agreement with experiment that is consistent with the low-pressure results.Comment: Minor revisions for consistency with published versio

Efeito do dimetildioctadecilamônio na resposta imune humoral e celular de cobaios inoculados com o herpesvírus bovino-1 inativado Effect of dimethyl dioctadecyl ammonium chloride on the humoral and cellular response to inactivated bovine herpesvirus-1 in guinea pigs

Avaliou-se o potencial adjuvante do cloreto de dimetildioctadecilamônio (DDA cloreto) em estimular as respostas imune humoral e celular, do tipo hipersensibilidade cutânea tardia (DTH), em cobaios que receberam preparações de antígeno contendo o herpesvírus bovino tipo 1 (BHV-1) inativado. Os animais foram vacinados com o BHV-1 em cinco diferentes formulações, representadas pelos grupos: A- adjuvante completo / incompleto de Freund, B- hidróxido de alumínio (Al(OH)3), C- DDA cloreto, D- associação Al(OH)3 / DDA cloreto e E- BHV-1 em solução aquosa sem adjuvante. Os animais do grupo F, grupo-controle negativo, foram inoculados apenas com meio de cultivo celular. Os maiores títulos de anticorpos neutralizantes do BHV-1, expressos em log2, foram obtidos nos grupos D, A e C, com títulos de 6,25, 6,0 e 5,25, respectivamente. Na avaliação da DTH, os maiores aumentos na espessura da dobra da pele foram observados nos grupos A (2,4mm), C (1,8mm) e D (1,1mm). O DDA cloreto, utilizado tanto de forma isolada quanto em associação, determinou a potencialização das respostas imunológicas humoral e celular de cobaios imunizados com o BHV-1 inativado.<br>The adjuvanticity of dimethyl dioctadecyl ammonium chloride (DDA chloride) to induce humoral and cell mediated (delayed type hypersensitivity - DTH -) immune responses was assessed in guinea pigs that received antigen preparations containing inactivated bovine herpesvirus type 1 (BHV-1). The animals were vaccinated with five different formulations, containing BHV-1 represented by groups: A- complete/incomplete Freund adjuvant, B- aluminum hydroxide (Al(OH)3), C- DDA chloride, D- association Al(OH)3/DDA and E- BHV-1 in aqueous solution without adjuvant. Group F was the negative control group and the animals received only cell culture medium. The higher titers of BHV-1 neutralizing antibodies, expressed in log2, were obtained in groups D, A and C with values of 6.25, 6.0 and 5.25, respectively. In the DTH assessment, the higher increase in skin thickness was observed in group A (2.4mm), C (1.8mm) and D (1.1mm). These results showed that DDA chloride used alone or in association to other substance boosted the humoral and cell mediated immune responses in guinea pigs immunized with inactivated BHV-1

Effects of lattice disorder in the UCu

The UCu(5-x)Pd(x) system exhibits non-Fermi liquid (NFL) in the thermodynamic and transport properties at low temperatures for Pd concentrations 0.9 <~ x <~ 1.5. The local structure around the U, Cu, and Pd atoms has been measured for 0 <= x <= 1.5 using the X-ray Absorption Fine Structure (XAFS) technique in order to quantify the effects of lattice disorder on the NFL properties. A model which allows a percentage of the Pd atoms to occupy nominal Cu (16e) sites, s, was used to fit the Pd and Cu K edge and U L(III) edge data. Pd/Cu site interchange was found to occur in all samples (x != 0), reaching a minimum value of s ~0.17 at x = 0.7 and increasing monotonically to s ~ 0.4 at x=1.5. These data also determine the static disorder the nearest neighbor U--Cu pairs. The results indicate that the measured U--Cu static disorder is not sufficient to explain the NFL behavior of the magnetic susceptibility within the single-ion Kondo disorder model and casts doubt on the applicability of this model to UCu(5-x)Pd(x).Comment: 14 pages, 12 EPS figures, Phys. Rev. B, in pres

Is Public Capital Productive? Evidence from a Meta-analysis

Debate exists over the role that public investment must play in economic recovery and economic growth. The underlying idea behind this debate has much to do with the value of output elasticity of public capital. This article presents a meta-analysis of this elasticity, which was performed by considering almost 2,000 elasticities previously estimated from 145 papers. In addition, for each elasticity, we also take into account some 30 associated features relative to the methodology used for each case or relative to the characteristics of data samples. The obtained results reveal an average short-term elasticity of 0.13 (0.16 in the long term). We also find evidence of the importance of the methodology adopted for the obtained results, as well as the publication bias. Finally, we find a minor reduction in the value of the elasticity as public capital endowments increase. The results obtained highlight the positive and important effect of public investment on productivity. As a results of the value obtained, public investment will be self-financed in the long-term because of generated returns. But, we also find that the effectiveness of public investment has a clear influence of the institutional context

Phylogenomics and the rise of the angiosperms

Angiosperms are the cornerstone of most terrestrial ecosystems and human livelihoods1,2. A robust understanding of angiosperm evolution is required to explain their rise to ecological dominance. So far, the angiosperm tree of life has been determined primarily by means of analyses of the plastid genome3,4. Many studies have drawn on this foundational work, such as classification and first insights into angiosperm diversification since their Mesozoic origins5,6,7. However, the limited and biased sampling of both taxa and genomes undermines confidence in the tree and its implications. Here, we build the tree of life for almost 8,000 (about 60%) angiosperm genera using a standardized set of 353 nuclear genes8. This 15-fold increase in genus-level sampling relative to comparable nuclear studies9 provides a critical test of earlier results and brings notable change to key groups, especially in rosids, while substantiating many previously predicted relationships. Scaling this tree to time using 200 fossils, we discovered that early angiosperm evolution was characterized by high gene tree conflict and explosive diversification, giving rise to more than 80% of extant angiosperm orders. Steady diversification ensued through the remaining Mesozoic Era until rates resurged in the Cenozoic Era, concurrent with decreasing global temperatures and tightly linked with gene tree conflict. Taken together, our extensive sampling combined with advanced phylogenomic methods shows the deep history and full complexity in the evolution of a megadiverse clade