1,216 research outputs found
Testing international price transmission under policy intervention. An application to the soft wheat market
No full textHorizontal Price Transmission in Agricultural Markets: Fundamental Concepts and Open Empirical Issues
Full text linkFollowing the dramatic changes experienced by the prices of agricultural commodities in 2007-2008, the analysis of horizontal price transmission mechanisms in agricultural markets has attracted renewed interest. In particular, this has led to the emergence of new challenges for the empirical analysis. How to model the increasing volatility and non linear behaviour of prices, to assess the impact of the policy responses to market turbulence, and how to account for the increasing interconnections between agricultural and non-agricultural commodity markets are amongst the most investigated issues. Building on a common analytical framework, this paper discusses and reviews the most recent methodological developments and empirical contributions in the field
Making the world market price endogenous within the AGMEMOD modelling framework: an econometric solution
Full text linkThis paper aims at making the world price endogenous within the AGMEMOD modelling approach. This approach constructs country-level commodity market models where supply and demand sides are equalized on the basis of the observed domestic prices. These prices are endogenous as they depend (price transmission equation) on a EU key-price, which is, in turn, endogenously determined by the world price (price formation equation). The world prices, however, are assumed to be exogenous. To make the world price endogenous, we propose a system of equations where the EU key-price and the world price are simultaneously determined. This system of equations, written in a dynamic and error-correction form (VECM), substitutes the usual price-formation equation, while price transmission across EU countries remains unaffected. This approach is here applied to the case of soft wheat and results compared to those obtained by using the conventional AGMEMOD approach.Price Formation and Transmission, Commodity Market Models, VECM, Demand and Price Analysis, Research Methods/ Statistical Methods, Q110, Q170,
Agricultural price transmission across space and commodities during price bubbles
No full textThis article investigates agricultural price transmission during price bubbles. The empirical approach concerns the horizontal transmission of cereal prices both across different market places and across different commodities. The trade policy intervention put forward to mitigate the impact
of price exuberance is considered. The analysis is performed using Italian and international weekly spot (cash) price data over years 2006–2010, a period of generalized turbulence of agricultural markets. Firstly, the properties of price time series are explored; then, interdependence across
prices is specified and estimated by adopting appropriate cointegration techniques. Results suggest that the bubble had only a slight impact on the price spread and the temporary trade-policy measure, when effective, has limited this impact
Price Transmission in the Swiss Wheat Market: Does Sophisticated Border Protection Make the Difference?
Full text linkThis study deals with horizontal wheat price transmission from the international markets to the domestic Swiss market. The analysis takes into account trade policies implemented at the borders that might shelter the domestic market from international markets fluctuations, as well as the presence of explosive behavior in some of the price series. Furthermore, the Swiss case is peculiar due to the presence of different border policies for wheat according to its domestic use, food or feed. The paper investigates price transmission in this segregated domestic market under the respective different border policies but still acknowledging possible linkages among the two market segments. Vector Error Correction models with structural breaks are estimated, allowing to account for the influence of periods of market exuberance in the international markets as well as of the consequent policy regime changes
Agricultural Price Transmission Across Space and Commodities During Price Bubbles
Full text linkThis paper analyses the horizontal transmission of cereal price shocks both across different market places and across different commodities. The analysis is carried out using Italian and international weekly spot (cash) price data and concentrating the attention on years 2006-2010, a period of generalized exceptional exuberance and consequent rapid drop of agricultural prices. The work aims at investigating how price transmission may be affected during price bubbles. The properties of price time series are firstly explored to assess which data generation process may have eventually produced the observed patterns. Secondly, the interdependence across prices is specified and estimated adopting appropriate cointegration techniques.Price Transmission, Price Bubbles, Time Series Properties, Cointegration, Demand and Price Analysis, Q110, C320,
Giulia Veronica Varisco
No full textThe headword explains the biography and the contribution of the author Giulia Varisco to the children's literatur
Molecular characterization of Marek’s disease virus detected in backyard chickens affected by classical nervous form
No full textAn outbreak of Marek’s disease nervous form in unvaccinated Cochin chickens from an Italian
backyard flock is reported. After suppression two birds, showing inability to stand upright and
spastic paralysis of legs, were necropsied and organs were taken for histologic examination and
molecular analysis. MDV-1 was detected from feathers by PCR targeting meq gene.meq gene
of the detected strain was fully sequenced along with commercial vaccines most commonly
used in Italy. Nucleotide and amino acid sequences were compared to selected MDV-1
reference strains with different degrees of pathogenicity, retrieved from GenBank. The
sequence analysis and the high number of PPPP repeats found in the transactivation domain
of the Meq protein showed that the detected virus was closely related to mild or attenuated
MDV-1 strains, but different from the analyzed vaccines. The molecular results were supported
by clinical, macroscopic and microscopic findings. A- and B-type lesions, highly suggestive of a
mild MDV-1 infection, were observed in peripheral nerves.MHC haplotype B19, known to be
correlated with high susceptibility to Marek’s disease, was found in affected chickens by PCR
and sequencing of B-LβII family genes. Because sequencing of the meq gene is not a sufficient
criteria in determining the pathotype, virus isolation will be attempted in order to confirm the
molecular results by in vivo experimental trials
Molecular characterization of avian metapneumovirus from Guinea fowls (numida meleagridis)
Full text linkIn the present study the subtype B aMPV, strain aMPV/B/IT/GuineaFowl/1818/12, was detected in Guinea fowls affected by respiratory signs, sequenced and molecularly characterized. Comparisons among several F and G gene full sequences of aMPVs subtype B, showed that no consistent pattern related to host-tropism could be identified. Moreover, analysis of partial G gene revealed the perfect identity of the Guinea fowl strain with four Italian aMPVs isolated from turkeys or chickens in a time frame of three years, in the same geographic area. Phylogenetic analysis of both genes showed an evolutionary trend of subtype B circulating in Northern Italy from its first appearance in 1987, to date. The co-presence in the same geographic area of farms housing different avian species sensitive to aMPV, vaccinated with different vaccination programs or not vaccinated (like Guinea fowls), and often belonging to the same integrate poultry company, could be a crucial factor for the establishment of an endemic infection. © 2018 PVJ. All rights reserved
Ytterbium Disilicate/Monosilicate Multilayer Environmental Barrier Coatings: Influence of Atmospheric Plasma Spray Parameters on Composition and Microstructure
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Ytterbium Disilicate/Monosilicate Multilayer Environmental Barrier Coatings: Influence of Atmospheric Plasma Spray Parameters on Composition and Microstructure
by Giulia Di Iorio,Laura Paglia *ORCID,Giulia PedrizzettiORCID,Virgilio GenovaORCID,Francesco MarraORCID,Cecilia BartuliORCID andGiovanni PulciORCID
INSTM Reference Laboratory for Materials and Surface Engineering, Sapienza University of Rome, Eudossiana 18, 00184 Rome, Italy
*
Author to whom correspondence should be addressed.
Coatings 2023, 13(9), 1602; https://doi.org/10.3390/coatings13091602
Original submission received: 10 August 2023 / Revised: 31 August 2023 / Accepted: 11 September 2023 / Published: 13 September 2023
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Abstract
SiC/SiC ceramic matrix composites (SiCf/SiC CMCs) are regarded as the new materials for the hot-section components of aircraft gas turbine engines, since they have one-third of the density of metallic superalloys, a higher temperature capability, good mechanical strength, and excellent thermal shock resistance. However, high-temperature water-vapor-rich combustion gases can induce severe surface recession phenomena in SiC/SiC leading to component failure. For this reason, it is necessary to design protective coatings, i.e., environmental barrier coatings (EBCs), able to protect the SiC/SiC surface in combustion environments. In the present work, ytterbium monosilicate (Yb2SiO5), stable when exposed to water vapor at high temperatures, and ytterbium disilicate (Yb2Si2O7), characterized by a thermal expansion coefficient closer to that of the substrate, were selected for a multilayer EBC system. EBCs were processed using the atmospheric plasma spray (APS) technique. A set of deposition parameters were tested, varying the power of the torch, and the composition and microstructure of the deposited coatings were studied in terms of porosity, crack density, and post-deposition phase retention by performing SEM, EDS, and XRD analysis. The results allow for the definition of the influence of deposition parameters on the final properties of multilayer EBC coatings
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