21,181 research outputs found
Late Triassic (Rhaetian) conodonts and ichthyoliths from Chile
The Late Triassic of the back arc Domeyko Basin, Chile is characterized by the onset of marine sedimentation that persisted throughout the rest of the Mesozoic. Carbonate bulk samples from the Punta del Viento Limestone Formation have yielded a numerically small, but apparently widespread, conodont fauna including Epigondolella mosheri, Epigondolella englandi and Neogondolella steinbergensis. These specimens indicate a Rhaetian (Epigondolella mosheri conodont Biozone roughly equivalent to the Paracochloceras amoenum ammonoid Biozone) age for this unit. Their recovery represents the first record of conodonts from Chile, and also indicates a considerable potential for use in correlating sequence stratigraphic events within the Mesozoic Marginal Sea in Colombia, Peru and Chile
Non-linear spin Seebeck effect due to spin-charge interaction in graphene
The abilities to inject and detect spin carriers are fundamental for research
on transport and manipulation of spin information. Pure electronic spin
currents have been recently studied in nanoscale electronic devices using a
non-local lateral geometry, both in metallic systems and in semiconductors. To
unlock the full potential of spintronics we must understand the interactions of
spin with other degrees of freedom, going beyond the prototypical electrical
spin injection and detection using magnetic contacts. Such interactions have
been explored recently, for example, by using spin Hall or spin thermoelectric
effects. Here we present the detection of non-local spin signals using
non-magnetic detectors, via an as yet unexplored non-linear interaction between
spin and charge. In analogy to the Seebeck effect, where a heat current
generates a charge potential, we demonstrate that a spin current in a
paramagnet leads to a charge potential, if the conductivity is energy
dependent. We use graphene as a model system to study this effect, as recently
proposed. The physical concept demonstrated here is generally valid, opening
new possibilities for spintronics
The Extended Invariant Factor Algorithm with Application to the Forney Analysis of Convolutional Codes
In his celebrated paper on the algebraic structure of convolutional codes, Forney showed that by using the invariant-factor theorem, one can transform an arbitrary polynomial generator matrix for an (n, k) convolutional code C into a basic (and ultimately a minimal) generator matrix for C. He also showed how to find a polynomial inverse for a basic generator matrix for C, and a basic generator matrix for the dual code C^⊥. In this paper, we will discuss efficient ways to do all these things. Our main tool is the “entended invariant factor algorithm,” which we introduce here
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