Composition, distribution and supposed origin of mineral inclusions in sessile oak wood - consequences for microdensitometrical analysis

SEM and light-microscopical observations, supported by chemical microanalysis with an EDXA system, revealed that light-saturated pixels observed in X-ray negatives of sessile oak (Quercus petraea Liebl.) wood were caused by inorganic deposits present inside multiseriate ray and axial parenchyma cells. Calcium oxalate crystals, silica grains and amorphous granules with varied mineral compositions have been identified. The wood strips of three out of six sampled trees contained measurable amounts of mineral inclusions which were quantified using image analysis. Based on the variations of mineral content observed between trees and within and between annual rings of the same tree, some hypotheses were formulated concerning the factors involved in the formation of inorganic deposits in oak wood. Their occurrence varies depending on the mineral concerned and seems to be controlled largely by a tree effect. The time of formation appears to coincide with a shifting of the oak wood’s functions as a result of heartwood formation processes (inter-annual scale) or changes in leaf phenology and climate (intra-annual scale). In addition, the technical consequences of their presence as well as their effects on wood density measurements through microdensitometry are discussedComposition, distribution et origine supposée d’inclusions minérales dans le bois de chêne sessile – conséquences pour l’analyse microdensitométrique. Des observations à l’aide de microscopes électronique à balayage et optique, appuyées par des analyses élémentaires au moyen d’un système EDXA, ont révélé que les points-images saturés en niveau de gris, constatés dans les négatifs de radiographies de bois de chêne sessile (Quercus petraea Liebl.), étaient dus à des dépôts inorganiques présents à l’intérieur des cellules parenchymateuses des rayons ligneux multisériés et du parenchyme axial. Des cristaux d’oxalate de calcium, des grains de silice et des granules amorphes ayant des compositions minérales variées ont été identifiés. Des barrettes de trois sur six arbres échantillonnés contenaient des quantités mesurables d’inclusions minérales qui ont été quantifiées par analyse d’images. En se basant sur les variations du contenu en dépôts minéraux observées entre arbres ainsi qu’à l’intérieur d’un arbre, aux niveaux intra- et intercerne, quelques hypothèses ont été avancées concernant les facteurs potentiellement responsables de la formation de dépôts minéraux chez le chêne. Leur présence dépend du minéral concerné et semble être contrôlée par un fort effet arbre. L’apparition des minéraux coïncide apparemment avec des changements de fonctions du bois relatifs aux processus de duraminisation (échelle interannuelle) ou correspondant à des évolutions phénologiques ou climatiques (échelle intra-annuelle). Enfin, les conséquences techniques ainsi que les effets de leur présence sur des mesures de la densité du bois par analyse microdensitométrique sont discuté

Experimentos computacionales en la resolución del problema de códigos de identificación

El Problema de Códigos de Identificación (PCI) es un problema NP-difícil relativamente nuevo que, además de contar con aplicaciones concretas (véase el trabajo de Karpovsky, Chakrabarty y Levitin, On a new class of codes for identifying vertices in graphs. IEEE Trans. Inf. Theory 44, 599–611), es desafiante tanto desde el punto de vista teórico como computacional. En particular, se han propuesto algoritmos polinomiales para resolver el PCI sobre clases particulares de grafos y, más recientemente, se ha estudiado el poliedro asociado a su formulación natural donde, en algunos casos, se ha dado la descripción completa para algunas familias de grafos (véase el trabajo de Argiroffo, Bianchi y Wagler, Study of Identifying Code Polyhedra for Some Families of Split Graphs, LNCS 8596, 13–25). En esta comunicación reportamos algunos experimentos computacionales respecto a la performance de un modelo de programación entera para el PCI.Sociedad Argentina de Informática e Investigación Operativa (SADIO

Experimentos computacionales en la resolución del problema de códigos de identificación

El Problema de Códigos de Identificación (PCI) es un problema NP-difícil relativamente nuevo que, además de contar con aplicaciones concretas (véase el trabajo de Karpovsky, Chakrabarty y Levitin, On a new class of codes for identifying vertices in graphs. IEEE Trans. Inf. Theory 44, 599–611), es desafiante tanto desde el punto de vista teórico como computacional. En particular, se han propuesto algoritmos polinomiales para resolver el PCI sobre clases particulares de grafos y, más recientemente, se ha estudiado el poliedro asociado a su formulación natural donde, en algunos casos, se ha dado la descripción completa para algunas familias de grafos (véase el trabajo de Argiroffo, Bianchi y Wagler, Study of Identifying Code Polyhedra for Some Families of Split Graphs, LNCS 8596, 13–25). En esta comunicación reportamos algunos experimentos computacionales respecto a la performance de un modelo de programación entera para el PCI.Sociedad Argentina de Informática e Investigación Operativa (SADIO

Thermodynamically self-consistent non-stochastic micromagnetic model for the ferromagnetic state

In this work, a self-consistent thermodynamic approach to micromagnetism is presented. The magnetic degrees of freedom are modeled using the Landau-Lifshitz-Baryakhtar theory, that separates the different contributions to the magnetic damping, and thereby allows them to be coupled to the electron and phonon systems in a self-consistent way. We show that this model can quantitatively reproduce ultrafast magnetization dynamics in Nickel.Comment: 5 pages, 3 figure

Phase 2, Open-Label, International, Non-Comparative Study of MEDI4736 in Patients with Locally Advanced or Metastatic, Pd-L1 +, Stage 3B–4 Nsclc Who Have Received ≥2 Prior Systemic Treatment Regimens (ATLANTIC)

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FASTER: Facilitating Analysis and Synthesis Technologies for Effective Reconfiguration

The FASTER (Facilitating Analysis and Synthesis Technologies for Effective Reconfiguration) EU FP7 project, aims to ease the design and implementation of dynamically changing hardware systems. Our motivation stems from the promise reconfigurable systems hold for achieving high performance and extending product functionality and lifetime via the addition of new features that operate at hardware speed. However, designing a changing hardware system is both challenging and time-consuming. FASTER facilitates the use of reconfigurable technology by providing a complete methodology enabling designers to easily specify, analyze, implement and verify applications on platforms with general-purpose processors and acceleration modules implemented in the latest reconfigurable technology. Our tool-chain supports both coarse- and fine-grain FPGA reconfiguration, while during execution a flexible run-time system manages the reconfigurable resources. We target three applications from different domains. We explore the way each application benefits from reconfiguration, and then we asses them and the FASTER tools, in terms of performance, area consumption and accuracy of analysis

Large microwave generation from d.c. driven magnetic vortex oscillators in magnetic tunnel junctions

Spin polarized current can excite the magnetization of a ferromagnet through the transfer of spin angular momentum to the local spin system. This pure spin-related transport phenomena leads to alluring possibilities for the achievement of a nanometer scale, CMOS compatible and tunable microwave generator operating at low bias for future wireless communications. Microwave emission generated by the persitent motion of magnetic vortices induced by spin transfer effect seems to be a unique manner to reach appropriate spectral linewidth. However, in metallic systems, where such vortex oscillations have been observed, the resulting microwave power is much too small. Here we present experimental evidences of spin-transfer induced core vortex precessions in MgO-based magnetic tunnel junctions with similar good spectral quality but an emitted power at least one order of magnitude stronger. More importantly, unlike to others spin transfer excitations, the thorough comparison between experimental results and models provide a clear textbook illustration of the mechanisms of vortex precessions induced by spin transfer