Thermal effects on electron-phonon interaction in silicon nanostructures

Raman spectra from silicon nanostructures, recorded using excitation laser power density of 1.0 kW/cm^2, is employed here to reveal the dominance of thermal effects at temperatures higher than the room temperature. Room temperature Raman spectrum shows only phonon confinement and Fano effects. Raman spectra recorded at higher temperatures show increase in FWHM and decrease in asymmetry ratio with respect to its room temperature counterpart. Experimental Raman scattering data are analyzed successfully using theoretical Raman line-shape generated by incorporating the temperature dependence of phonon dispersion relation. Experimental and theoretical temperature dependent Raman spectra are in good agreement. Although quantum confinement and Fano effects persists, heating effects start dominating at higher temperatures than room tempaerature.Comment: 9 Pages, 3 Figures and 1 Tabl

U–Pb Zircon geochronology of the Cambro-Ordovician metagranites and metavolcanic rocks of central and NW Iberia

New U–Pb zircon data from metagranites and metavolcanic rocks of the Schist-Graywacke Complex Domain and the Schistose Domain of Galicia Tras-os-Montes Zone from central and NW Iberia contribute to constrain the timing of the Cambro-Ordovician magmatism from Central Iberian and Galicia Tras-os-Montes Zones which occurred between 498 and 462 Ma. The crystallization ages of the metagranites and metavolcanic rocks from the northern Schist-Graywacke Complex Domain are as follows: (a) in west Salamanca, 489 ± 5 Ma for Vitigudino, 486 ± 6 Ma for Fermoselle and 471 ± 7 Ma for Ledesma; (b) in northern Gredos, 498 ± 4 Ma for Castellanos, 492 ± 4 Ma for San Pelayo and 488 ± 3 Ma for Bercimuelle; (c) in Guadarrama, 490 ± 5 Ma for La Estacion I, 489 ± 9 Ma for La Canada, 484 ± 6 Ma for Vegas de Matute (leucocratic), 483 ± 6 Ma for El Cardoso, 482 ± 8 Ma for La Morcuera, 481 ± 9 Ma for Buitrago de Lozoya, 478 ± 7 Ma for La Hoya, 476 ± 5 Ma for Vegas de Matute (melanocratic), 475 ± 5 Ma for Riaza, 473 ± 8 Ma for La Estacion II and 462 ± 11 Ma for La Berzosa; and (d) in Toledo, 489 ± 7 Ma for Mohares and 480 ± 8 Ma for Polan. The crystallization ages of the metagranites from the Schistose Domain of Galicia Tras-os-Montes Zone are 497 ± 6 Ma for Laxe, 486 ± 8 Ma for San Mamede, 482 ± 7 Ma for Bangueses, 481 ± 5 Ma for Noia, 480 ± 10 for Rial de Sabucedo, 476 ± 9 Ma for Vilanova, 475 ± 6 Ma for Pontevedra, 470 ± 6 Ma for Cherpa and 462 ± 8 Ma for Bande.This magmatism is characterized by an average isotopic composition of (87Sr/86Sr)485Ma ≈ 0.712, (eNd)485Ma ≈ -4.1 and (TDM) ≈ 1.62 Ga, and a high zircon inheritance, composed of Ediacaran–Early Cambrian (65 %) and, to a lesser extent, Cryogenian, Tonian, Mesoproterozoic, Orosirian and Archean pre-magmatic cores. Combining our geochronological and isotopic data with others of similar rocks from the European Variscan Belt, it may be deduced that Cambro-Ordovician magmas from this belt were mainly generated by partial melting of Ediacaran–Early Cambrian igneous rocks

Beyond a Dichotomy of Perspectives: Understanding Religion on the Basis of Paul Natorp’s Logic of Boundary

Based on Paul Natorp’s (1854–1924) late post-Neo-Kantian “Logic of Boundary” (German: “Grenzlogik”) I will offer a methodically controlled, non-reductionist and equally anti-essentialist reconstruction of the notion of religion. The pre-eminent objective of this reconstructive work is to overcome the well-known epistemological as well as methodological problem of a dichotomy between inside and outside perspectives on the subject of religion. Differently put, the objective consists in an attempt to demonstrate that there actually is “reason in religion” that is intellectually accessible for academic knowledge production. Following Natorp’s splendid formulation I will argue that religion operates neither ‘within’ nor ‘beyond’ the ‘boundary of humanity’ but exactly on [or ‘in’] this boundary. More precisely, I will explicate that religious praxis (including its specific production of knowledge) from Natorp’s standpoint can be understood as the performative realization, and habitual embodiment of the (contextually concrete) boundary of humanity or human reason itself. Due to its principial self-referentiality this boundary carries the crucial sense of a first and last positive and, therefore, both in theoretical terms definitive and in practical terms eminently instructive notion of boundary with no outside. This paradoxically all-enclosing, positive boundary, while explicitly including life’s inevitable negativity but, nonetheless, able to ideally sublate it, is the reason why the practice of religion, as empirical evidence unmistakably documents, can provide an incommensurably fulfilling, significant and meaningful closure with regards to the innermost self-perception of its practitioners (concerning their self-determination or agency)

Self-tolerance in multiple sclerosis

During the last decade, several defects in self-tolerance have been identified in multiple sclerosis. Dysfunction in central tolerance leads to the thymic output of antigen-specific T cells with T cell receptor alterations favouring autoimmune reactions. In addition, premature thymic involution results in a reduced export of naïve regulatory T cells, the fully suppressive clone. Alterations in peripheral tolerance concern costimulatory molecules as well as transcriptional and epigenetic mechanisms. Recent data underline the key role of regulatory T cells that suppress Th1 and Th17 effector cell responses and whose immunosuppressive activity is impaired in patients with multiple sclerosis. Those recent observations suggest that a defect in self-tolerance homeostasis might be the primary mover of multiple sclerosis leading to subsequent immune attacks, inflammation and neurodegeneration. The concept of multiple sclerosis as a consequence of the failure of central and peripheral tolerance mechanisms to maintain a self-tolerance state, particularly of regulatory T cells, may have therapeutic implications. Restoring normal thymic output and suppressive functions of regulatory T cells appears an appealing approach. Regulatory T cells suppress the general local immune response via bystander effects rather than through individual antigen-specific responses. Interestingly, the beneficial effects of currently approved immunomodulators (interferons β and glatiramer acetate) are associated with a restored regulatory T cell homeostasis. However, the feedback regulation between Th1 and Th17 effector cells and regulatory T cells is not so simple and tolerogenic mechanisms also involve other regulatory cells such as B cells, dendritic cells and CD56bright natural killer cells

Geology and tectono-metamorphic evolution of the Read Group, Shackleton Range: a part of the East Antarctic Craton

Geological mapping and new structural observations during the 1994/95 EUROSHACK Expedition lead us to propose a new lithological subdivision of the Proterozoic Read Group, which is exposed in a tectonic window framed by the Ross-age low-grade Mount Wegener Nappe in the southern Shackleton Range. The oldest rock-units of the Read Group comprise several varieties of high-grade gneisses, ranging in composition from pelitic to quartzo-feldspathic and mafic, interlayered with minor amphibolites, Ca-silicate rocks, quartzites, marbles and serpentinites. On the basis of the petrological evidence provided by the mafic gneisses, the metamorphic evolution of these rock units includes at least three main metamorphic stages: a medium-P granulite facies stage (8 kbar, ca. 800°C) (M1), a low-P upper amphibolite to granulite facies stage (5 kbar, ca. 700 °C) (M2), and a low-P lower-amphibolite to greenschist facies stage (M3). Several distinct plutonic suites were distinguished and mapped. They range from syn-metamorphic metaluminous to peraluminous granitoids to post-tectonic swarms of peraluminous granitic dykes. The plutonic suites were emplaced mainly after M1 and throughout M2. The overall tectono-metamorphic evolution from M1 to M3 is interpreted as a continuous record of the exhumation of a thickened crust, controlled mainly by extension and triggered by voluminous magmatism in middle-Proterozoic time. Younger, Ross-age deformation and greenschist facies metamorphism occur mainly close to the contact zone with the Mount Wegener Nappe and provide evidence for reactivation of the Proterozoic Read Group associated with its incorporation, under a prevailing transpressional regime, within the Ross-age thrust-fold system of the Shackleton Range