New data on the stratigraphy and chronology of the prehistoric site of Prazo (Freixo de Numão)

O sítio arqueológico do Prazo situa-se na freguesia de Freixo de Numão (Vila Nova deFoz Côa, Nordeste de Portugal). Após a sua descoberta, no início dos anos 80, o Prazo foialvo de várias campanhas de escavação orientadas para o estudo da villa romana e dos vestígiosmedievais existentes no local. Em 1996, os trabalhos de campo puseram a descobertoníveis datados do Neolítico Antigo. Entre 1997 e 2001, as escavações realizadas centraramsena análise destes níveis pré-históricos, revelando a existência de uma espessa sequênciaestratigráfica que, para além de conservar depósitos residuais plistocénicos, incluía igualmentesedimentos atribuíveis a grande parte do Holocénico antigo e médio. Este artigo pretendeapresentar a geoarqueologia e a cronologia da sequência pré-histórica do Prazo, quese organiza essencialmente em três conjuntos: um conjunto do Plistocénico superior (conjuntoPS), constituído por depósitos de vertente, e contendo um registo arqueológico (artefactoslíticos e estruturas antrópicas) datado provisoriamente do Paleolítico superior; umconjunto atribuído ao Holocénico antigo e médio (conjunto HA), igualmente composto por sedimentos de vertente e que forneceu elementos arqueológicos do Epipaleolítico/Mesolí-tico e do Neolítico Antigo; um conjunto do Holocénico recente (conjunto HR), correspondenteàs ocupações romanas e medievais do local. Neste texto discutem-se igualmente asdatações radiométricas disponíveis. Estes dados, embora preliminares, visam esclarecer questõesrelacionadas com a evolução ambiental do local e com as estratégias da sua ocupaçãodurante a Pré-história.The Prazo archaeological site is located near Freixo de Numão (Vila Nova deFoz Côa, north-eastern Portugal). The site, discovered in the early 80s, initially revealed asignificant historical record, having been a Roman villawhose occupation continued throughpart of the Middle Ages. In 1996, fieldwork there uncovered Neolithic layers. They were excavatedfrom 1997 to 2001, revealing also the existence of a pre-Neolithic occupation. Thispaper presents the geoarchaeology and chronology of the prehistoric succession of Prazo,which is arranged as follows: an upper Pleistocene complex formed of slope waste sediments,featuring upper Palaeolithic finds and structures; an early to mid Holocene succession, alsocomposed from slope waste deposits, containing Epipalaeolithic/Mesolithic and EarlyNeolithic archaeological assemblages and features; and an upper Holocene complex, correspondingto occupations in the Roman and Middle Ages. The available data deriving fromthe geoarchaeological survey at the site and from an extensive range of radiocarbon dates are presented as part of a preliminary discussion of the environmental evolution and thesettlement strategies at the site

Effective lattice actions for correlated electrons

We present an exact, unconstrained representation of the electron operators in terms of operators of opposite statistics. We propose a path--integral representation for the $t$-$J$ model and introduce a parameter controlling the semiclassical behaviour. We extend the functional approach to the Hubbard model and show that the mean--field theory is equivalent to considering, at Hamiltonian level, the Falikov--Kimball model. Connections with a bond-charge model are also discussed.Comment: 12 pages, REVTeX 3.0, no figure

Sulodexide counteracts endothelial dysfunction induced by metabolic or non-metabolic stresses through activation of the autophagic program

OBJECTIVE: Endothelial dysfunction (ED) predisposes to venous thrombosis (VT) and post-thrombotic syndrome (PTS), a long-term VT-related complication. Sulodexide (SDX) is a highly purified glycosaminoglycan with antithrombotic, pro-fibrinolytic and anti-inflammatory activity used in the treatment of chronic venous disease (CVD), including patients with PTS. SDX has recently obtained clinical evidence in the “extension therapy” after initial-standard anticoagulant treatment for the secondary prevention of recurrent deep vein thrombosis (DVT). Herein, we investigated how SDX counteracts ED. MATERIALS AND METHODS: Human umbilical vein endothelial cells (HUVEC) were used. Metabolic and non metabolic-induced ED was induced by treating with methylglyoxal (MGO) or irradiation (IR), respectively. Bafilomycin A1 was used to inhibit autophagy. The production of reactive oxygen species (ROS), tetrazolium bromide (MTT) assay for cell viability, terminal de-oxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay for cell apoptosis, Real-time PCR and Western blot analysis for gene and protein expression were used. RESULTS: SDX protected HUVEC from MGO- or IR-induced apoptosis by counteracting the activation of the intrinsic and extrinsic caspase cascades. The cytoprotective effects of SDX resulted from a reduction in a) ROS production, b) neo-synthesis and release of pro-inflammatory cytokines (TNFα, IL1, IL6, IL8), c) DNA damage induced by MGO or IR. These effects were reduced when autophagy was inhibited. CONCLUSIONS: Data herein collected indicate the ability of SDX to counteract ED induced by metabolic or non-metabolic stresses by involving the intracellular autophagy pathway. Our experience significantly increases the knowledge of the mechanisms of action of SDX against ED and supports the use of SDX in the treatment of CVD, PTS and in the secondary prevention of recurrent DVT

The sequential price of anarchy for atomic congestion games

In situations without central coordination, the price of anarchy relates the quality of any Nash equilibrium to the quality of a global optimum. Instead of assuming that all players choose their actions simultaneously, here we consider games where players choose their actions sequentially. The sequential price of anarchy, recently introduced by Paes Leme, Syrgkanis, and Tardos then relates the quality of any subgame perfect equilibrium to the quality of a global optimum. The effect of sequential decision making on the quality of equilibria, however, depends on the specific game under consideration.\ud Here we analyze the sequential price of anarchy for atomic congestion games with affine cost functions. We derive several lower and upper bounds, showing that sequential decisions mitigate the worst case outcomes known for the classical price of anarchy. Next to tight bounds on the sequential price of anarchy, a methodological contribution of our work is, among other things, a "factor revealing" integer linear programming approach that we use to solve the case of three players

Hole dynamics in a quantum antiferromagnet beyond the retraceable path approximation

The one-hole spectral weight for two chains and two dimensional lattices is studied numerically using a new method of analysis of the spectral function within the Lanczos iteration scheme: the Lanczos spectra decoding method. This technique is applied to the $t-J_z$ model for $J_z \to 0$, directly in the infinite size lattice. By a careful investigation of the first 13 Lanczos steps and the first 26 ones for the two dimensional and the two chain cases respectively, we get several new features of the one-hole spectral weight. A sharp incoherent peak with a clear momentum dispersion is identified, together with a second broad peak at higher energy. The spectral weight is finite up to the Nagaoka energy where it vanishes in a non-analytic way. Thus the lowest energy of one hole in a quantum antiferromagnet is degenerate with the Nagaoka energy in the thermodynamic limit.Comment: RevTeX 3.0, SISSA preprint 156/93/CM/MB, 10 pages + postscript file appended, contains more accurate calculations in Fig.

The qq-boson-fermion realizations of quantum suprealgebra Uq(gl(2/1))U_q(gl(2/1))

We show that our construction of realizations for Lie algebras and quantum algebras can be generalized to quantum superalgebras, too. We study an example of quantum superalgebra $U_q(gl(2/1))$ and give the boson-fermion realization with respect to one pair od q-deformed boson operator and 2 pairs of fermions.Comment: 8 page

Single hole dynamics in the t-J model on a square lattice

We present quantum Monte Carlo (QMC) simulations for a single hole in a t-J model from J=0.4t to J=4t on square lattices with up to 24 x 24 sites. The lower edge of the spectrum is directly extracted from the imaginary time Green's function. In agreement with earlier calculations, we find flat bands around $(0,\pm\pi)$, $(\pm\pi,0)$ and the minimum of the dispersion at $(\pm\pi/2,\pm\pi/2)$. For small J both self-consistent Born approximation and series expansions give a bandwidth for the lower edge of the spectrum in agreement with the simulations, whereas for J/t > 1, only series expansions agree quantitatively with our QMC results. This band corresponds to a coherent quasiparticle. This is shown by a finite size scaling of the quasiparticle weight $Z(\vec k)$ that leads to a finite result in the thermodynamic limit for the considered values of $J/t$. The spectral function $A(\vec k, \omega)$ is obtained from the imaginary time Green's function via the maximum entropy method. Resonances above the lowest edge of the spectrum are identified, whose J-dependence is quantitatively described by string excitations up to J/t=2

Language of CTO interventions – Focus on hardware

AbstractThe knowledge of variety of chronic total occlusion (CTO) hardware and the ability to use them represents the key to success of any CTO interventions. However, the multiplicity of CTO hardware and their physical character and the terminology used by experts create confusion in the mind of an average interventional cardiologist, particularly a beginner in this field. This knowledge is available but is scattered. We aim to classify and compare the currently used devices based on their properties focusing on how physical character of each device can be utilized in a specific situation, thus clarifying and simplifying the technical discourse

Quantum Monte Carlo simulations of infinitely strongly correlated fermions

Numerical simulations of the two-dimensional t-J model in the limit $J/t \ll 1$ are performed for rather large systems (up to $N = 12 \times 12$) using a world-line loop-algorithm. It is shown that in the one-hole case with J=0, where no minus signs appear, very low temperatures ($\beta t \sim 3000$) are necessary in order to reach Nagaoka's state. J/t \ltsim 0.05 leads to the formation of partially polarized systems, whereas J/t \gtsim 0.05 corresponds to minimal spin. The two-hole case shows enhanced total spin up to the lowest attainable temperatures ($\beta t = 150$).Comment: 6 pages, 5 figure

Prospects for K+→π+ννˉK^+ \to \pi^+ \nu \bar{ \nu } at CERN in NA62

The NA62 experiment will begin taking data in 2015. Its primary purpose is a 10% measurement of the branching ratio of the ultrarare kaon decay $K^+ \to \pi^+ \nu \bar{ \nu }$, using the decay in flight of kaons in an unseparated beam with momentum 75 GeV/c.The detector and analysis technique are described here.Comment: 8 pages for proceedings of 50 Years of CP