Visualization by scanning SQUID microscopy of the intermediate state in the superconducting Dirac semimetal PdTe2{}_2

The Dirac semimetal PdTe${}_2$ becomes superconducting at a temperature $T_{c}=1.6$~K. Thermodynamic and muon spin rotation experiments support type-I superconductivity, which is unusual for a binary compound. A key property of a type-I superconductor is the intermediate state which presents a coexistence of superconducting and normal domains (flux structures) at magnetic fields lower than the thermodynamic critical field $H_{c}$. By means of scanning SQUID microscopy (SSM) we observe flux structures in the superconducting state of PdTe${}_2$. The flux structures are strongly history dependent with a transition from round shapes to laminar shapes as the magnetic field is more and more increased. The field amplitudes measured at the surface are indicative for the presence of Landau branching. The domain wall width in the intermediate state has been determined.Comment: 8 pages 5 figure

Fundamentos econômicos da formação do preço internacional de açucar e dos preços domésticos de açucar e etanol.

O objetivo deste estudo foi investigar os fatores que afetam o comportamento do etanol no mercado interno e os preços do açúcar nos mercados doméstico e internacional. Três ordens de fatores explicativos são considerados para o preço internacional: (a) índice geral de preços das commodities CRB Spot, (b) macro-fatores (taxa de câmbio, juros, liquidez) (c) fatores idiossincráticos relacionados ao mercado mundial de açúcar. Os fatores explicativos para os preços brasileiros de açúcar e etanol são: (a) preço internacional do açúcar, (b) macro fatores nacionais e internacionais (c) fatores idiossincráticos (clima, produtividade). O preço internacional é previsto principalmente pelo índice CRB e preços do petróleo. Relacionado ao mercado interno, o preço do açúcar foi previsto pelos preços internacionais e taxa de câmbio do real. Os erros de previsão permaneceram na faixa de 20%. No caso dos preços de etanol, os preços internacionais e domésticos do açúcar foram os principais preditores, embora os erros tenham atingido 40%. Como o etanol é commodity menos negociadas no exterior, seus preços são mais sensíveis a fatores idiossincráticos. No entanto, permanece a conclusão geral de que o comportamento dos preços do açúcar e etanol no mercado brasileiro é bastante coerente com o mercado global de commodities

Input-Output Relations in Optical Cavities: a Simple Point of View

In this work we present a very simple approach to input-output relations in optical cavities, limiting ourselves to one- and two-photon states of the field. After field quantization, we derive the non-unitary transformation between {\em Inside} and {\em Outside} annihilation and creation operators. Then we express the most general two-photon state generated by {\em Inside} creation operators, through base states generated by {\em Outside} creation operators. After renormalization of coefficients of inside two-photon state, we calculate the outside photon-number probability distribution in a general case. Finally we treat with some detail the single mode and symmetrical cavity case.Comment: 34 pages, 5 figures jpg, LaTe

Drought tolerance and antioxidant enzymatic activity in transgenic ?Swingle? citrumelo plants over-accumulating proline.

In this study we investigated the effects of the high endogenous proline level on water relations, gas exchange and antioxidant enzymatic activity in leaves of transgenic ?Swingle? citrumelo rootstocks transformed with the P5CSF129A gene coding for the key-enzyme for proline synthesis, under water deficit. Leaf total water, osmotic and pressure potentials, stomatal conductance, photosynthetic rates and xylem sapflowwere evaluated in non-transformed control and transgenic plants during water deficit treatment. Malondialdehyde (MDA) content, catalase (CAT; EC 1.11.1.6), superoxide dismutase (SOD; EC 1.15.1.1) and ascorbate peroxidase (APX; EC 1.11.1.11) activities were quantified in leaves collected based on their total water potential, representing the following conditions: irrigated (w =−1.3 MPa), moderate stress (w =−2.3 to −2.5 MPa), severe stress (w =−3.8 to −3.9 MPa) and recovery (24 h after re-irrigation: w =−1.3 to −1.9 MPa). Osmotic adjustment was observed in transgenic plants until 11 days after withholding water, while pressure potential in non-transformed controls was close to zero after nine days of water deprivation. This superior maintenance of turgor pressure in leaves of transgenic plants led to higher stomatal conductance, photosynthetic and transpiration rates when compared to non-transgenic plants. Drought caused a significant decrease in APX and SOD activities in control plants, followed by an increase after re-watering. On the other hand, CAT was more active in control than in transgenic plants under irrigated condition and both stress levels. Our results suggest that transgenic plants were able to cope with water deficit better than non-transformed controls since the high endogenous proline level acted not only by mediating osmotic adjustment, but also by contributing to gas exchange parameters and ameliorating deleterious effects of drought-induced oxidative stress