Mechanisms of Spontaneous Current Generation in an Inhomogeneous d-Wave Superconductor

A boundary between two d-wave superconductors or an s-wave and a d-wave superconductor generally breaks time-reversal symmetry and can generate spontaneous currents due to proximity effect. On the other hand, surfaces and interfaces in d-wave superconductors can produce localized current-carrying states by supporting the T-breaking combination of dominant and subdominant order parameters. We investigate spontaneous currents in the presence of both mechanisms and show that at low temperature, counter-intuitively, the subdominant coupling decreases the amplitude of the spontaneous current due to proximity effect. Superscreening of spontaneous currents is demonstrated to be present in any d-d (but not s-d) junction and surface with d+id' order parameter symmetry. We show that this supercreening is the result of contributions from the local magnetic moment of the condensate to the spontaneous current.Comment: 4 pages, 5 figures, RevTe

Effective field theory analysis of the self-interacting chameleon

We analyse the phenomenology of a self-interacting scalar field in the context of the chameleon scenario originally proposed by Khoury and Weltman. In the absence of self-interactions, this type of scalar field can mediate long range interactions and simultaneously evade constraints from violation of the weak equivalence principle. By applying to such a scalar field the effective field theory method proposed for Einstein gravity by Goldberger and Rothstein, we give a thorough perturbative evaluation of the importance of non-derivative self-interactions in determining the strength of the chameleon mediated force in the case of orbital motion. The self-interactions are potentially dangerous as they can change the long range behaviour of the field. Nevertheless, we show that they do not lead to any dramatic phenomenological consequence with respect to the linear case and solar system constraints are fulfilled.Comment: 15 pages, 2 figures. Final version accepted for publication on General Relativity and Gravitatio

Antihypertensive therapeutic potential of citronellal

Cardiovascular effects induced by citronellal in rats were investigated in this study. In LNAME hypertensive rats, the oral acute administration of citronellal (200 mg/kg) was able to significantly reduce the blood pressure. In normotensive rats, citronellal (5-40 mg/kg, i.v.) induced hypotension, which was not affected by pre-treatment with atropine, hexamethonium, L-NAME or indomethacin, and bradycardia, which was abolished by atropine and hexamethonium, but not by L-NAME or indomethacin. ECG records revealed that citronellal induced sinoatrial block, which was abolished after atropine. In intact rings of rat mesenteric artery pre-contracted with phenylephrine (10 μM), citronellal (10 –6 to 10 –1 M) was able to induce relaxations (Emax = 106.3 ± 9.4 %) that were not affected by endothelium removal or after pre-contraction with KCl 80 mM. In conclusion, these results demonstrate that citronellal reduces blood pressure. Furthermore, citronellal induces endothelium-independent vasorelaxation in rat artery that appears to involve inhibition of Ca2+ influx.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Models of quintessence coupled to the electromagnetic field and the cosmological evolution of alpha

We study the change of the effective fine structure constant in the cosmological models of a scalar field with a non-vanishing coupling to the electromagnetic field. Combining cosmological data and terrestrial observations we place empirical constraints on the size of the possible coupling and explore a large class of models that exhibit tracking behavior. The change of the fine structure constant implied by the quasar absorption spectra together with the requirement of tracking behavior impose a lower bound of the size of this coupling. Furthermore, the transition to the quintessence regime implies a narrow window for this coupling around $10^{-5}$ in units of the inverse Planck mass. We also propose a non-minimal coupling between electromagnetism and quintessence which has the effect of leading only to changes of alpha determined from atomic physics phenomena, but leaving no observable consequences through nuclear physics effects. In doing so we are able to reconcile the claimed cosmological evidence for a changing fine structure constant with the tight constraints emerging from the Oklo natural nuclear reactor.Comment: 13 pages, 10 figures, RevTex, new references adde

Population genomics of post-glacial western Eurasia.

Western Eurasia witnessed several large-scale human migrations during the Holocene <sup>1-5</sup> . Here, to investigate the cross-continental effects of these migrations, we shotgun-sequenced 317 genomes-mainly from the Mesolithic and Neolithic periods-from across northern and western Eurasia. These were imputed alongside published data to obtain diploid genotypes from more than 1,600 ancient humans. Our analyses revealed a 'great divide' genomic boundary extending from the Black Sea to the Baltic. Mesolithic hunter-gatherers were highly genetically differentiated east and west of this zone, and the effect of the neolithization was equally disparate. Large-scale ancestry shifts occurred in the west as farming was introduced, including near-total replacement of hunter-gatherers in many areas, whereas no substantial ancestry shifts happened east of the zone during the same period. Similarly, relatedness decreased in the west from the Neolithic transition onwards, whereas, east of the Urals, relatedness remained high until around 4,000 BP, consistent with the persistence of localized groups of hunter-gatherers. The boundary dissolved when Yamnaya-related ancestry spread across western Eurasia around 5,000 BP, resulting in a second major turnover that reached most parts of Europe within a 1,000-year span. The genetic origin and fate of the Yamnaya have remained elusive, but we show that hunter-gatherers from the Middle Don region contributed ancestry to them. Yamnaya groups later admixed with individuals associated with the Globular Amphora culture before expanding into Europe. Similar turnovers occurred in western Siberia, where we report new genomic data from a 'Neolithic steppe' cline spanning the Siberian forest steppe to Lake Baikal. These prehistoric migrations had profound and lasting effects on the genetic diversity of Eurasian populations