Vortex Lattice in Bi_{2}Sr_{2}CaCu_{2}O_{8+\delta} Well Above the First-Order Phase-Transition Boundary

Measurements of non-local in-plane resistance originating from transverse vortex-vortex correlations have been performed on a Bi_{2}Sr_{2}CaCu_{2}O_{8+\delta} high-T_c superconductor in a magnetic field up to 9 T applied along the crystal c-axis. Our results demonstrate that a rigid vortex lattice does exist over a broad portion of the magnetic field -- temperature (H-T) phase diagram, well above the first-order transition boundary H_{FOT}(T). The results also provide evidence for the vortex lattice melting and vortex liquid decoupling phase transitions, occurring above the H_{FOT}(T).Comment: 14 pages, 10 figure

EVALUATION OF HUMAN EXPOSURE TO HEXACHLOROBENZENE AT SAMARITÁ, SÃO VICENTE, SÃO PAULO, BRAZIL

Na área de Samaritá, cidade de São Vicente, São Paulo, Brasil, resíduos químicos industriais foram descartados por vários anos, sem proteção ambiental, contendo 55 a 85% de hexaclorobenzeno (HCB) e outros produtos em menores quantidades. Para avaliar o impacto à saúde foram analisados soro sangüíneo de 234 pessoas de diversos bairros da região, com mais de 2 anos de residência, subdivididos em 6 setores: A - Quarentenário e vizinhança do lixo industrial a 67 km; B - Jardim Rio Branco; C - Parque das Bandeiras; D - Gleba II; E - Vila Samaritá; F - Vila Ema, Vila Iolanda, Vila Mathias. Dez amostras de soro sangüíneo de habitantes de Itanhaém, área considerada não exposta, foram coletados para fornecer dados de referência. HCB não foi encontrado em nenhuma destas amostras. Resíduos de HCB foram analisados por cromatografia a gás com detetor de captura de elétrons e limite de determinação de 0,02 µg/dL. Os níveis médios de HCB no soro sanguíneo dos moradores mostraram-se significativamente diferentes (p < 0.001) entre o setor A (0.41µg/dL) e os demais setores: B (0.04 µg/dL); C (0.04 µg/ dL); D (0.03 µg/dL); E (0.04 µg/dL): F (0.04 µg/dL). Ainda que não seja possível estabelecer correlações com doenças encontradas na população, este estudo demonstra que os resíduos de HCB constituem problema para a saúde, pois além de contaminar o meio ambiente são encontrados em seres vivos, inclusive no ser humano. Abstract In the Samaritá area of São Vicente city, São Paulo State, Brazil, a chemical industry discarded for several years, with no environmental protection, a mixture of residues containing 55 to 85% of hexachlorobenzene (HCB) and others in smaller quantities. In order to evaluate the impact of these residues on the health of the local population, blood serum samples taken from 234 people dwelling at several quarters of this area for over two years were analyzed, divided into 6 sectors: A - Quarentenário and neighborhood of the industrial wastes dump at 67-km; B - Jardim Rio Branco; C - Parque das Bandeiras; D - Gleba II; E -Vila Samaritá; F -Vila Ema, Vila Iolanda, Vila Mathias. Ten blood samples from residents of an area considered no exposed from Itanhaém city were collected to provide baseline information and HCB was not found in any of the samples. HCB residues were analysed by gas chromatography with an electron capture detector, with a determination limit of 0.02 µg/dL. The mean of HCB in blood serum for the inhabitants of the affected area presented significant differences (p < 0.001) between sector A (0.41 µg/dL) and all the others sectors: B (0.04 µg/dL); C (0.04 µg/ dL); D (0.03 µg/dL); E (0.04 µg/dL): F (0.04 µg/dL). Although it has not yet been possible to correlate such findings with the presence of diseases among the area inhabitants, this study indicates that the HCB residues are a health risk, as they not only contaminate the environment, but are also present at the biota, including humans

Negative c-axis magnetoresistance in graphite

We have studied the c-axis interlayer magnetoresistance (ILMR), R_c(B) in graphite. The measurements have been performed on strongly anisotropic highly oriented pyrolytic graphite (HOPG) samples in magnetic field up to B = 9 T applied both parallel and perpendicular to the sample c-axis in the temperature interval 2 K < T < 300 K. We have observed negative magnetoresistance, dR_c/dB < 0, for B || c-axis above a certain field B_m(T) that reaches its minimum value B_m = 5.4 T at T = 150 K. The results can be consistently understood assuming that ILMR is related to a tunneling between zero-energy Landau levels of quasi-two-dimensional Dirac fermions, in a close analogy with the behavior reported for alpha-(BEDT-TTF)2I3 [N. Tajima et al., Phys. Rev. Lett. 102, 176403 (2009)], another multilayer Dirac electron system.Comment: 14 pages, including 4 figure

Ultrafast photoisomerisation of an isolated retinoid

The photoinduced excited state dynamics of gas-phase trans-retinoate (deprotonated trans-retinoic acid, trans-RA−) are studied using tandem ion mobility spectrometry coupled with laser spectroscopy, and frequency-, angle- and time-resolved photoelectron imaging. Photoexcitation of the bright S3(ππ*) ← S0 transition leads to internal conversion to the S1(ππ*) state on a ≈80 fs timescale followed by recovery of S0 and concomitant isomerisation to give the 13-cis (major) and 9-cis (minor) photoisomers on a ≈180 fs timescale. The sub-200 fs stereoselective photoisomerisation parallels that for the retinal protonated Schiff base chromophore in bacteriorhodopsin. Measurements on trans-RA− in methanol using the solution photoisomerisation action spectroscopy technique show that 13-cis-RA− is also the principal photoisomer, although the 13-cis and 9-cis photoisomers are formed with an inverted branching ratio with photon energy in methanol when compared with the gas phase, presumably due to solvent-induced modification of potential energy surfaces and inhibition of electron detachment processes. Comparison of the gas-phase time-resolved data with transient absorption spectroscopy measurements on retinoic acid in methanol suggest that photoisomerisation is roughly six times slower in solution. This work provides clear evidence that solvation significantly affects the photoisomerisation dynamics of retinoid molecules

Estruturas De Poder Nas Redes De Financiamento Político Nas Eleições De 2010 No Brasil

This article analyses 299,968 relationships established between 251,665 actors (donors and/or recipients) of financial legal resources declared by candidates and parties in all positions at stake in the 2010 elections in Brazil. Data from the Tribunal Superior Eleitoral (Superior Electoral Court) was used, together with the methodology of social network analysis and complementary statistical procedures, to explore the topology of the subnets (components) and of the calculations of the centrality of the actors - candidates, party agents and private funders. The results show the high connectivity and asymmetry of the campaign finance network in Brazil and they expose that the positioning of the actors in the network layers is crucial to the performances of both the candidates and the funders, revealing, in an unprecedented way, the existence of a political elite within the Brazilian electoral system.221285

Local and global superconductivity in bismuth

We performed magnetization M(H,T) and magnetoresistance R(T,H) measurements on powdered (grain size ~ 149 μm) as well as highly oriented rhombohedral (A7) bismuth (Bi) samples consisting of single crystalline blocks of size ~ 1×1 mm in the plane perpendicular to the trigonal c axis. The obtained results revealed the occurrence of (1) local superconductivity in powdered samples with Tc(0) = (8.75 ± 0.05) K, and (2) global superconductivity at Tc(0) = (7.3 ± 0.1) K in polycrystalline Bi triggered by low-resistance ohmic contacts with silver (Ag) normal metal. The results provide evidence that the superconductivity in Bi is localized in a tiny volume fraction, probably at intergrain or Ag/Bi interfaces. On the other hand, the occurrence of global superconductivity observed for polycrystalline Bi can be accounted for by enhancement of the superconducting order parameter phase stiffness induced by the normal metal contacts, the scenario proposed in the context of “pseudogap regime” in cuprates [E. Berg et al., Phys. Rev. B78, 094509 (2008)]

Productive aspects of pigs fed forage cactus silage associated with feed restriction

This study aimed to evaluate the use of silage of forage cactus (Opuntia ficus-indica Mill) in diets for finishing pigs. Two experiments were conducted: the first for digestibility and the second for performance. In the performance trial, the quantitative levels of feed restriction (0%, 10%, 20%, and 30%) were evaluated, which were associated with the supply of forage cactus silage. Forage cactus silage presented 2463.59 and 2456 kcal/kg of digestible and metabolizable energy, respectively. The feed restriction levels associated with the supply of forage cactus silage influenced feed intake, weight gain and final weight negatively, but did not affect feed conversion. Carcass absolute weight was influenced negatively. However, the yield of carcass and cuts and the amount of meat in the carcass were not influenced. With the increase in feed restriction, there was a decrease in duodenal mucosa thickness, intestinal glands, liver glycogen storage and the occurrence of inflammation in the submucosa and intestinal mucosa. Forage cactus silage is not accepted well by animals. The restriction up to 30% of balanced feed did not affect feed conversion, yield of carcass and cuts and economic viability. However, levels over 10% affected intestinal health.Keywords: Alternative feed, feed preservation, intestinal health, Opuntia ficus-indica Mill, pig nutritio

Resistive Random Access Memories (RRAMs) Based on Metal Nanoparticles

It is demonstrated that planar structures based on silver nanoparticleshosted in a polymer matrix show reliable and reproducible switching properties attractive for non-volatile memory applications. These systems can be programmed between a low conductance (off-state) and high conductance (on-state) with an on/off ratio of 3 orders of magnitude, large retention times and good cycle endurance. The planar structure design offers a series of advantages discussed in this contribution, which make it an ideal tool to elucidate the resistive switching phenomena

Vasodilators in Septic Shock Resuscitation: A Clinical Perspective

ABSTRACT: Microcirculatory abnormalities have been shown to be frequent in patients with septic shock despite “normalization” of systemic hemodynamics. Several studies have explored the impact of vasodilator therapy (prostacyclin, inhaled nitric oxide, topic acetylcholine and nitroglycerin) on microcirculation and tissue perfusion, with contradictory findings.In this narrative review, we briefly present the pathophysiological aspects of microcirculatory dysfunction, and depict the evidence supporting the use of vasodilators and other therapeutic interventions (fluid administration, blood transfusion, vasopressors and dobutamine) aiming to improve the microcirculatory flow in septic shock patients

Field theoretic description of charge regulation interaction

In order to find the exact form of the electrostatic interaction between two proteins with dissociable charge groups in aqueous solution, we have studied a model system composed of two macroscopic surfaces with charge dissociation sites immersed in a counterion-only ionic solution. Field-theoretic representation of the grand canonical partition function is derived and evaluated within the mean-field approximation, giving the Poisson-Boltzmann theory with the Ninham-Parsegian boundary condition. Gaussian fluctuations around the mean-field are then analyzed in the lowest order correction that we calculate analytically and exactly, using the path integral representation for the partition function of a harmonic oscillator with time-dependent frequency. The first order (one loop) free energy correction gives the interaction free energy that reduces to the zero-frequency van der Waals form in the appropriate limit but in general gives rise to a mono-polar fluctuation term due to charge fluctuation at the dissociation sites. Our formulation opens up the possibility to investigate the Kirkwood-Shumaker interaction in more general contexts where their original derivation fails.Comment: 12 pages, 9 figures, submitted to EPJ