Oil and Product Price Dynamics in International Petroleum Markets

In this paper we investigate crude oil and products price dynamics. We present a comparison among ten price series of crude oils and fourteen price series of petroleum products, considering four distinct market areas (Mediterranean, North Western Europe, Latin America and North America) over the period 1994-2002. We provide first a complete analysis of crude oil and product price dynamics using cointegration and error correction models. Subsequently we use the error correction specification to predict crude oil prices over the horizon January 2002-June 2002.The main findings of the paper can be summarized as follows: a) differences in quality are crucial to understand the behaviour of crudes; b) prices of crude oils whose physical characteristics are more similar to the marker show the following regularities: b1) they converge more rapidly to the long-run equilibrium; b2) there is an almost monotonic relation between Mean Absolute Percentage Error values and crude quality, measured by API° gravity and sulphur concentration; c) the price of the marker is the driving variable of the crude price also in the short-run, irrespective of the specific geographical area and the quality of the crude under analysis.Oil prices, Product prices, Error correction models, Forecasting

Conditional Correlations in the Returns on Oil Companies Stock Prices and Their Determinants

The identification of the forces that drive stock returns and the dynamics of their associated volatilities is a major concern in empirical economics and finance. This analysis is particularly relevant for determining optimal hedging strategies based on whether shocks to the volatilities of returns of oil companies stock prices, relevant stock market indexes and oil spot and futures prices are high or low, and positively or negatively correlated. This paper investigates the correlations of volatilities in the stock price returns and their determinants for the most important integrated oil companies, namely Bp (BP), Chevron-Texaco (CVX), Eni (ENI), Exxon-Mobil (XOM), Royal Dutch (RD) and Total-Fina Elf (TFE). We measure the actual co-risk in stock returns and their determinants “within” and “between” the different oil companies, using multivariate cointegration techniques in modelling the conditional mean, as well as multivariate GARCH models for the conditional variances. We focus first on the determinants of the market value of each company using the cointegrated VAR/VECM methodology. Then we specifiy the conditional variances of VECM residuals with the Constant Conditional Correlation (CCC) multivariate GARCH model of Bollerslev (1990) and the Dynamic Conditional Correlation (DCC) multivariate GARCH model of Engle (2002). The “within” and “between” DCC indicate low to high/extreme interdependence between the volatilities of companies’ stock returns and the relevant stock market indexes or Brent oil prices.Constant conditional correlations, Dynamic conditional correlations, Multivariate GARCH models, Stock price indexes, Brent oil prices, Spot and futures prices, Multivariate cointegration, VECM

Oil and product price dynamics in international petroleum markets

In this paper we investigate crude oil and products price dynamics. We present a comparison among ten prices series of crude oils and fourteen price series of petroleum products, considering four distinct market areas (Mediterranean, North Western Europe, Latin America and North America) over the period 1994-2002. We provide first a complete analysis of crude oil and product price dynamics using cointegration and error correction models. Subsequently we use the error correction specification to predict crude oil prices over the horizon January 2002-June 2002.The main findings of the paper can be summarized as follows: a) differences in quality are crucial to understand the behaviour of crudes; b) prices of crude oils whose physical characteristics are more similar to the marker show the following regularities: b1) they converge more rapidly to the long-run equilibrium; b2) there is an almost monotonic relation between Mean Absolute Percentage Error values and crude quality, measured by API° gravity and sulphur concentration; c) the price of the marker is the driving variable of the crude price also in the short-run, irrespective of the specific geographical area and the quality of the crude under analysis

unsteady methods applied to a transonic aeronautical gas turbine stage

Abstract The importance of considering the unsteady effects in aeronautical engine design has brought to the implementation of simplified unsteady CFD models to respect the temporal restrictions of design cycles. A comparison among steady, Non-Linear Harmonic (NLH) and Full-Annulus (FA) methods has been carried out analyzing the transonic turbine stage CT3, experimentally studied at von Karman Institute for Fluid Dynamics. The understanding of the unsteady phenomena is fundamental to increase the engine efficiency and is precluded in steady calculations. As the computational cost of NLH calculations is of the same order of magnitude of steady ones, it represents a valid and competitive option in a turbine design process

Mega-parsec scale magnetic fields in low density regions in the SKA era: filaments connecting galaxy clusters and groups

The presence of magnetic fields in galaxy clusters has been well established in recent years, and their importance for the understanding of the physical processes at work in the Intra Cluster Medium has been recognized. Halo and relic sources have been detected in several tens clusters. A strong correlation is present between the halo and relic radio power and the X-ray luminosity. Since cluster X-Ray luminosity and mass are related, the correlation between the radio power and X-ray luminosity could derive from a physical dependence of the radio power on the cluster mass, therefore the cluster mass could be a crucial parameter in the formation of these sources. The goal of this project is to investigate the existence of non-thermal structures beyond the Mpc scale, and associated with lower density regions with respect to clusters of galaxies: galaxy filaments connecting rich clusters. We present a piece of evidence of diffuse radio emission in intergalactic filaments. Moreover, we present and discuss the detection of radio emission in galaxy groups and in faint X-Ray clusters, to analyze non-thermal properties in low density regions with physical conditions similar to galaxy filaments. We discuss how SKA1 observations will allow the investigation of this topic and the study of the presence of diffuse radio sources in low density regions. This will be a fundamental step to understand the origin and properties of cosmological magnetic fields.Comment: 9 pages, 5 figures - to appear as part of 'Cosmic Magnetism' in Proceedings 'Advancing Astrophysics with the SKA (AASKA14)', PoS(AASKA14)10

Reducing Secondary Flow Losses in Low-Pressure Turbines: The "Snaked" Blade

This paper presents an innovative design for reducing the impact of secondary flows on the aerodynamics of low-pressure turbine (LPT) stages. Starting from a state-of-the-art LPT stage, a local reshaping of the stator blade was introduced in the end-wall region in order to oppose the flow turning deviation. This resulted in an optimal stator shape, able to provide a more uniform exit flow angle. The detailed comparison between the baseline stator and the redesigned one allowed for pointing out that the rotor row performance increased thanks to the more uniform inlet flow, while the stator losses were not significantly affected. Moreover, it was possible to derive some design rules and to devise a general blade shape, named 'snaked', able to ensure such results. This generalization translated in an effective parametric description of the 'snaked' shape, in which few parameters are sufficient to describe the optimal shape modification starting from a conventional design. The "snaked" blade concept and its design have been patented by Avio Aero. The stator redesign was then applied to a whole LPT module in order to evaluate the potential benefit of the 'snaked' design on the overall turbine performance. Finally, the design was validated by means of an experimental campaign concerning the stator blade. The spanwise distributions of the flow angle and pressure loss coefficient at the stator exit proved the effectiveness of the redesign in providing a more uniform flow to the successive row, while preserving the original stator losses

Comparisons of Cosmological MHD Galaxy Cluster Simulations to Radio Observations

Radio observations of galaxy clusters show that there are $\mu$G magnetic fields permeating the intra-cluster medium (ICM), but it is hard to accurately constrain the strength and structure of the magnetic fields without the help of advanced computer simulations. We present qualitative comparisons of synthetic VLA observations of simulated galaxy clusters to radio observations of Faraday Rotation Measure (RM) and radio halos. The cluster formation is modeled using adaptive mesh refinement (AMR) magneto-hydrodynamic (MHD) simulations with the assumption that the initial magnetic fields are injected into the ICM by active galactic nuclei (AGNs) at high redshift. In addition to simulated clusters in Xu et al. (2010, 2011), we present a new simulation with magnetic field injections from multiple AGNs. We find that the cluster with multiple injection sources is magnetized to a similar level as in previous simulations with a single AGN. The RM profiles from simulated clusters, both $|RM|$ and the dispersion of RM ($\sigma_{RM}$), are consistent at a first-order with the radial distribution from observations. The correlations between the $\sigma_{RM}$ and X-ray surface brightness from simulations are in a broad agreement with the observations, although there is an indication that the simulated clusters could be slightly over-dense and less magnetized with respect to those in the observed sample. In addition, the simulated radio halos agree with the observed correlations between the radio power versus the cluster X-ray luminosity and between the radio power versus the radio halo size. These studies show that the cluster wide magnetic fields that originate from AGNs and are then amplified by the ICM turbulence (Xu et al. 2010) match observations of magnetic fields in galaxy clusters.Comment: Accepted for publication in Ap

Relativistic plasma and ICM/radio source interaction

The first detection of a diffuse radio source in a cluster of galaxies, dates back to the 1959 (Coma Cluster, Large et al. 1959). Since then, synchrotron radiating radio sources have been found in several clusters, and represent an important cluster component which is linked to the thermal gas. Such sources indicate the existence of large scale magnetic fields and of a population of relativistic electrons in the cluster volume. The observational results provide evidence that these phenomena are related to turbulence and shock-structures in the intergalactic medium, thus playing a major role in the evolution of the large scale structure in the Universe. The interaction between radio sources and cluster gas is well established in particular at the center of cooling core clusters, where feedback from AGN is a necessary ingredient to adequately describe the formation and evolution of galaxies and host clusters.Comment: 8 pages, Review talk at the 274 IAU Symposium "Advances in Plasma Astrophysics", 6-10 Sept 2010, Giardini Naxos, Italy, A. Bonanno, E. de Gouveia Dal Pino and A. Kosovichev, ed

Fully Polarizable QM/Fluctuating Charge Approach to Two-Photon Absorption of Aqueous Solutions

We present the extension of the quantum/classical polarizable fluctuating charge model to the calculation of single residues of quadratic response functions, as required for the computational modeling of two-photon absorption cross-sections. By virtue of a variational formulation of the quantum/classical polarizable coupling, we are able to exploit an atomic orbital-based quasienergy formalism to derive the additional coupling terms in the response equations. Our formalism can be extended to the calculation of arbitrary order response functions and their residues. The approach has been applied to the challenging problem of one- and two-photon spectra of rhodamine 6G (R6G) in aqueous solution. Solvent effects on one- and two-photon spectra of R6G in aqueous solution have been analyzed by considering three different approaches, from a continuum (QM/PCM) to two QM/MM models (non-polarizable QM/TIP3P and polarizable QM/FQ). Both QM/TIP3P and QM/FQ simulated OPA and TPA spectra show that the inclusion of discrete water solvent molecules is essential to increase the agreement between theory and experiment. QM/FQ has been shown to give the best agreement with experiments

Venom from Cuban Blue Scorpion has tumor activating effect in hepatocellular carcinoma

Complementary and alternative medicine (CAM) is the term used to describe many kinds of products, practices, and systems that are not part of conventional medicine. Cancer patients usually do everything they can to combat the disease, manage its symptoms, and cope with the side effects of treatment. Unfortunately, patients who use CAM underestimate the risk of interaction with cancer therapy or worse they omit conventional therapy thus reducing the possibility of cancer remission. Herein we analyzed the effects of Vidatox 30 CH (venom extracted from the Junceus Rhopalurus scorpion) on hepatocellular carcinoma (HCC), the second leading cause of cancer-related deaths. We found out that Vidatox increases HCC proliferation and invasion whereas it does not seem to interact with sorafenib, the orally active multikinase inhibitor approved for the treatment of advanced hepatocellular carcinoma. Our results suggest that the concentration of Vidatox used in the present study has not anti-neoplastic effects and care must be taken in hiring Vidatox in patients with HCC