Defining Rules in Cost Spanning Tree Problems Through the Canonical Form

We define the canonical form of a cost spanning tree problem. The canonical form has the property that reducing the cost of any arc, the minimal cost of connecting agents to the source is also reduced. We argue that the canonical form is a relevant concept in this kind of problems and study a rule using it. This rule satisfies much more interesting properties than other rules in the literature. Furthermore we provide two characterizations. Finally, we present several approaches to this rule without using the canonical form.Cost spanning tree, Rules, Canonical form

Entanglement detection in coupled particle plasmons

When in close contact, plasmonic resonances interact and become strongly correlated. In this work we develop a quantum mechanical model, using the language of continuous variables and quantum information, for an array of coupled particle plasmons. This model predicts that when the coupling strength between plasmons approaches or surpasses the local dissipation, a sizable amount of entanglement is stored in the collective modes of the array. We also prove that entanglement manifests itself in far-field images of the plasmonic modes, through the statistics of the quadratures of the field, in what constitutes a novel family of entanglement witnesses. This protocol is so robust that it is indeed independent of whether our own model is correct. Finally, we estimate the amount of entanglement, the coupling strength and the correlation properties for a system that consists of two or more coupled nanospheres of silver, showing evidence that our predictions could be tested using present-day state-of-the-art technology.Comment: 8 pages (6 main text + 2 supplemental), 3 figure

Facies and local roodel for the aluvial deposits in the rio Mero basin and Sada peninsula (A Coruña, Galicia, NW Spain)

[Resumen] Los depósitos aluviales de la cuenca del río Mero y península de Sada se originaron en dos tipos diferenciados de ambientes fluviales; - Corrientes fluviales de tipo trenzado. - Cursos I conos torrenciales Dichos ambientes pueden ser reconocidos gracias a las asociaciones de facies que presentan habiéndose identificado cuatro asociaciones diferentes (proximales, medias, distales y de curso yI o cono torrencial). La sedimentación se desarrolló en un contexto temporal con alternancia de periodos con predominio de procesos alocíclicos opuestos a periodos con mayor importancia de procesos autocíclicos ambos caracterizados por dos tipos diferentes de disección. El producto de esta alternancia dió como resultado secuencias grano y energía decreciente separadas por hiatos erosivos en los que se produciría el aterrazamiento de los depósitos. Cronologicamente los depésitos sedimentarios de la cuenca del Mero corresponderían, a la falta de datos más precisos el registro del transito Terciario- Cuaternario en esta zona.[Abstract] Aluvial deposits of Mero basin and Sada peninsula was generated under two different kinds of fluvial environments: - Braided type fluvial currents. - Torrential fan/currents. This ennvironments can be recognized by their facies associations. Four facies associations have been recognized (proximal, middle, distal and torrential currents Ifan association). Sedimentation was developed on a temporal context whith alociclicautociclic processes periodes characterized by two different kinds of dissection. The result of this, was energy and fining-upwards sequences construction limited by erosiva hiatus. During erosive hiatus was produced the deposits trenchment. This deposits can be, by lack of more precise data, the Terciary-Quaternary age record in this zone

Magnetic-field control of near-field radiative heat transfer and the realization of highly tunable hyperbolic thermal emitters

We present a comprehensive theoretical study of the magnetic field dependence of the near-field radiative heat transfer (NFRHT) between two parallel plates. We show that when the plates are made of doped semiconductors, the near-field thermal radiation can be severely affected by the application of a static magnetic field. We find that irrespective of its direction, the presence of a magnetic field reduces the radiative heat conductance, and dramatic reductions up to 700% can be found with fields of about 6 T at room temperature. We show that this striking behavior is due to the fact that the magnetic field radically changes the nature of the NFRHT. The field not only affects the electromagnetic surface waves (both plasmons and phonon polaritons) that normally dominate the near-field radiation in doped semiconductors, but it also induces hyperbolic modes that progressively dominate the heat transfer as the field increases. In particular, we show that when the field is perpendicular to the plates, the semiconductors become ideal hyperbolic near-field emitters. More importantly, by changing the magnetic field, the system can be continuously tuned from a situation where the surface waves dominate the heat transfer to a situation where hyperbolic modes completely govern the near-field thermal radiation. We show that this high tunability can be achieved with accessible magnetic fields and very common materials like n-doped InSb or Si. Our study paves the way for an active control of NFRHT and it opens the possibility to study unique hyperbolic thermal emitters without the need to resort to complicated metamaterials.Comment: 21 pages, 10 figure

The western extremity of the fundamental surface of Galicia: The plateau of Santa Comba

[Abstract] The Plateau ofSanta ir Comba is a very degraded rest ofan old surface (Late-Mesozoic -Paleogene), ofcomplex history. It has a mean altitude of400 m, and it is located in the western part of the Coruñan province. Their main geomorfological elements are: the residual reliefs (Ievels Al, A2, A3, A4, between 500 and 700 m of altitude), the platform or basal surface of the Plateau ofSanta Comba, between 400 and 500 m (A6 and A5) and the several flats that compond the degradation surface ofthe basal surface (levels Bl, B2, Cl). The Plateau of Santa Comba is the westernmost secror the Fundamental Surface of Galicia, and therefore, it can be correlated with the Fundamental Surface of the Hesperian Massif of the Peninsula. Their etche character (chemical corrosion) is geomorfologicaly evident for the existence of residual forms (inselbergs) conserved on it. They consist of pseudo apalachian reliefs with elear development of rocky platforms and basal carvings, sometimes multiple (flared slopes), and smaller forms, (vasque, tafoni, etc) that are conserved specially well on the older residual reliefs. The layout of the old fluvial network, previous ro the definition of the western Galician Rías, still remains drawn on the basal surface of the Plateau ofSanta Comba. This layout has been partly used by the present Xallas river, although fossil reaches are also conserved, distinguishables for the disproportionate dimensions of the valley compared with the actual secondary net associated ro them. Both in the periphery of the Plateau of Santa Comba and in their interior, they are located the heads ofthe fluvial net generated as aconsequence ofthe opening ofthe Atlantic Ocean and the alpine compression (since Late Mesozoic ro roday). They have affected the old fluvial net by means of processes of captures. Finally, the genesis for etching (chemical corrosion) of the Plateau ofSanta Comba as well as other big forms associated ro it, (Ría de Muros, Meridian Depression and satellite depressions , residual reliefs, etc.) allow us to propose a new genetic model for the reliefofwestern Galicia, more elose ro the postulate forVON RICHTHOFEN (1901), with evacuation of the regolith, and exposing of the etche surfaces (chemical corrosion) for the fluvial activity than to the traditional actual model based on the blocks tecronic

Neogene evolution of the lower reach of the Tambre river

[Abstract] The present paper srudy the evolution of the lower part of the Tambre Basin duting the Neogene. The basin, the fluvial network and a group of features are analyzed, such as the asymmetry of the net, the entrenchement, steps, etc, that are present in the Tambre and also frequent in other fluvial systems of Galicia. Ir is settled down that the current configuration of the fluvial network has been reached after a complex system of captures, with inversion of the drainage directions. Such evolution is not presented like an anecdotic circunstance in the layout ofthe river but rather it is considered a remarkable example ofthe fluvial processes that have contributed to the modeling ofthe present relief of Western Galicia

Macromamíferos (suidos) de la cueva de Praducelos (Suegos, Lugo)

[Resumen] El trabajo describe un fragmento mandibular de Sus scrofa, hallado en un relleno de dolina del sistema cárstico fósil de Praducelos (Suegos, Lugo). Aunque fuera de contexto estratigráfico tiene un valor cient{fico relativo ante la escasez de datos sobre la fauna cuaternaria de Galicia.[Abstract] The note describe a find of mandibular fragment Sus Scrofa, irom dolina filling of fossil Karstic system of Praducelos (Suegos, Lugo). Althoug out of stratigraphic context, the find have a relative importance considered the scarcity of information about quaternary galician fauna