New family of potentials with analytical twiston-like solutions

In this letter we present a new approach to find analytical twiston models. The effective two-field model was constructed by a non-trivial combination of two one field systems. In such an approach we successfully build analytical models which are satisfied by a combination of two defect-like solutions, where one is responsible to twist the molecular chain by $180^{\,0}$, while the other implies in a longitudinal movement. Such a longitudinal movement can be fitted to have the size of the distance between adjacent molecular groups. The procedure works nicely and can be used to describe the dynamics of several other molecular chains.Comment: 7 pages, 3 figure

Open and hidden charm in proton-nucleus and heavy-ion collisions

We review the collectivity and the suppression pattern of charmed mesons - produced in proton-nucleus and nucleus-nucleus collisions at SPS (158 AGeV) and RHIC energies (21 ATeV) - in comparison to dynamical and thermal models. In particular, we examine the charmonium `melting' and the `comover dissociation' scenarios - implemented in a microscopic transport approach - in comparison to the available data from the SPS and RHIC. The analysis shows that the dynamics of c, c-bar quarks at RHIC are dominated by partonic or `pre-hadronic' interactions in the strongly coupled plasma stage. Both the `charmonium melting' and the hadronic `comover absorption and recreation model' are found, however, to be compatible with the experimental observation at SPS energies; the experimental ratio of Psi'/J/Psi versus centrality clearly favors the `hadronic comover' scenario. We find that the collective flow of charm in the purely hadronic Hadron-String Dynamics (HSD) transport appears compatible with the data at SPS energies, but substantially underestimates the data at top RHIC energies. Thus, the large elliptic flow v2 of D-mesons and the low R_AA(p_T) of J/Psi seen experimentally have to be attributed to early interactions of non-hadronic degrees of freedom. Simultaneously, we observe that non-hadronic interactions are mandatory in order to describe the narrowing of the J/Psi rapidity distribution from pp to central Au+Au collisions at the top RHIC energy. We demonstrate additionally that the strong quenching of low-pT J/Psi's in central Au+Au collisions indicates that a large fraction of final J/Psi mesons is created by a coalescence mechanism close to the phase boundary. Throughout this review we, furthermore, provide predictions for charm observables from Au+Au collisions at FAIR energies of 25-35 AGeV.Comment: review for Int. J. Mod. Phys. E, 75 pages, 50 figure

Is there a causal role for homocysteine concentration in blood pressure?:A Mendelian randomization study

Background: An understanding of whether homocysteine is a cause or a marker of increased blood pressure is relevant because blood homocysteine can be effectively lowered by safe and inexpensive interventions (e.g., vitamin B-6, B-9, and B-12 supplementation). Objective: The aim was to assess the causal influence of homocysteine on systolic and diastolic blood pressure (SBP and DBP, respectively) in adults with the use of Mendelian randomization (MR). Design: Data from the 1982 Pelotas Birth Cohort (Brazil) were used. A total of 4297 subjects were evaluated in 2004–2005 (mean age: 22.8 y). The association of homocysteine concentration with SBP and DBP was assessed by conventional ordinary least-squares (OLS) linear regression and 2-stage least-squares (2SLS) regression (MR analysis). The single nucleotide polymorphism (SNP) methylenetetrahydrofolate reductase (MTHFR) C677T (rs1801133) was used as proxy for homocysteine concentration. We also applied MR to data from the International Consortium for Blood Pressure (ICBP) genomewide association studies (>69,000 participants) using rs1801133 and additional homocysteine-associated SNPs as instruments. Results: In OLS regression, a 1-SD unit increase in log homocysteine concentration was associated with an increase of 0.9 (95% CI: 0.4, 1.4) mm Hg in SBP and of 1.0 (95% CI: 0.6, 1.4) mm Hg in DBP. In 2SLS regression, for the same increase in homocysteine, the coefficients were −1.8 mm Hg for SBP (95% CI: −3.9, 0.4 mm Hg; P = 0.01) and 0.1 mm Hg for DBP (95% CI: −1.5, 1.7 mm Hg; P = 0.24). In the MR analysis of ICBP data, homocysteine concentration was not associated with SBP (β = 0.6 mm Hg for each 1-SD unit increase in log homocysteine; 95% CI: −0.8, 1.9 mm Hg) but was positively associated with DBP (β = 1.1 mm Hg; 95% CI: 0.2, 1.9 mm Hg). The association of genetically increased homocysteine with DBP was not consistent across different SNPs. Conclusion: Overall, the present findings do not corroborate the hypothesis that homocysteine has a causal role in blood pressure, especially in SBP

Valor nutritivo de grãos de sorgo com diferentes texturas do endosperma para leitões.

Utilizaram-se 20 leitões machos castrados, com 28kg de peso, em ensaio biológico baseado em coleta total de fezes e de urina para a determinação dos valores de digestibilidade aparente da matéria seca (DAMS), de digestibilidade aparente da proteína bruta (DAPB), de energia digestível aparente (EDA) e de energia metabolizável aparente (EMA) de grãos de sorgo com diferentes texturas do endosperma. Os genótipos avaliados foram BR 007B (textura macia), BR 304 (textura intermediária) e se 283 (textura du."a). As dietas-teste foram compostas por 70% de dieta referência, à base de milho e de farelo de soja, e por 30% de grãos de sorgo. O experimento foi montado em esquema inteiramente ao acaso, com quatro tratamentos e cinco repetições. Os valores de DAMS, de DAPB, de EDA e de EMA, expressos na matéria seca, dos grãos do genótipo BR 007B foram 97,1%, 89,7%, 3.840kcal/kg e 3.685kcal/kg; os do genótipo BR 304 foram 92,0%, 82,9%, 3.645kcal/kg e 3.544kcal/kg; e os do genótipo SC 283 foram 83,3%, 78,5%, 3.078kcal/kg e 3.021 kcal/kg, respectivamente. Todas as quatro variáveis analisadas apresentaram valores mais altos (P<0,05) para o genótipo BR 007B em relação ao genótipo se 283, demonstrando a influência negativa da textura do endosperma sobre o valor nutritivo dos grãos de sorgo para suínos

Relative importance of driving force and electrostatic interactions in the reduction of multihaem cytochromes by small molecules

AbstractMultihaem cytochromes are essential to the energetics of organisms capable of bioremediation and energy production. The haems in several of these cytochromes have been discriminated thermodynamically and their individual rates of reduction by small electron donors were characterized. The kinetic characterization of individual haems used the Marcus theory of electron transfer and assumed that the rates of reduction of each haem by sodium dithionite depend only on the driving force, while electrostatic interactions were neglected. To determine the relative importance of these factors in controlling the rates, we studied the effect of ionic strength on the redox potential and the rate of reduction by dithionite of native Methylophilus methylotrophus cytochrome c″ and three mutants at different pH values. We found that the main factor determining the rate is the driving force and that Marcus theory describes this satisfactorily. This validates the method of the simultaneous fitting of kinetic and thermodynamic data in multihaem cytochromes and opens the way for further investigation into the mechanisms of these proteins