88 research outputs found
Electroweak Radiative Corrections to Higgs Production via Vector Boson Fusion using SCET: Numerical Results
Electroweak radiative corrections are computed for Higgs production through
vector boson fusion, qq->qqH, which is one of the most promising channels for
detecting and studying the Higgs boson at the LHC. Using soft-collinear
effective theory, we obtain numerical results for the resummed logarithmic
contributions to the hadronic cross section at next-to-leading logarithmic
order. We compare our results to HAWK and find good agreement below 2 TeV where
the logarithms do not dominate. The SCET method is at its best in the high LHC
energy domain where the corrections are found to be slightly larger than
predicted by HAWK and by other one-loop fixed order approximations. This is one
of the first tests of this formalism at the level of a hadronic cross section,
and demonstrates the viability of obtaining electroweak corrections for generic
processes without the need for difficult electroweak loop calculations.Comment: Some minor corrections, 4 refs. added. arXiv admin note: text overlap
with arXiv:1011.150
A Score-Driven Conditional Correlation Model for Noisy and Asynchronous Data: an Application to High-Frequency Covariance Dynamics
The analysis of the intraday dynamics of correlations among high-frequency
returns is challenging due to the presence of asynchronous trading and market
microstructure noise. Both effects may lead to significant data reduction and
may severely underestimate correlations if traditional methods for
low-frequency data are employed. We propose to model intraday log-prices
through a multivariate local-level model with score-driven covariance matrices
and to treat asynchronicity as a missing value problem. The main advantages of
this approach are: (i) all available data are used when filtering correlations,
(ii) market microstructure noise is taken into account, (iii) estimation is
performed through standard maximum likelihood methods. Our empirical analysis,
performed on 1-second NYSE data, shows that opening hours are dominated by
idiosyncratic risk and that a market factor progressively emerges in the second
part of the day. The method can be used as a nowcasting tool for high-frequency
data, allowing to study the real-time response of covariances to macro-news
announcements and to build intraday portfolios with very short optimization
horizons.Comment: 30 pages, 10 figures, 7 table
Filtering and Smoothing with Score-Driven Models
We propose a methodology for filtering, smoothing and assessing parameter and
filtering uncertainty in misspecified score-driven models. Our technique is
based on a general representation of the well-known Kalman filter and smoother
recursions for linear Gaussian models in terms of the score of the conditional
log-likelihood. We prove that, when data are generated by a nonlinear
non-Gaussian state-space model, the proposed methodology results from a
first-order expansion of the true observation density around the optimal
filter. The error made by such approximation is assessed analytically. As shown
in extensive Monte Carlo analyses, our methodology performs very similarly to
exact simulation-based methods, while remaining computationally extremely
simple. We illustrate empirically the advantages in employing score-driven
models as misspecified filters rather than purely predictive processes.Comment: 33 pages, 5 figures, 6 table
Soil contamination by heavy metals at Libiola abandoned copper mine, Italy
Exploitation of ores has surely represented a risk for contamination of environmental matrices for a long time. This paper reports the results of a study concerning soil contamination by heavy metals at Libiola abandoned copper mine (Italy). This deposit has surely got special importance in Italy because of its historical, environmental and mining features. From a historical viewpoint, Libiola deposit was known since Copper Age, with maximum exploitation at the end of the 19th century. Our investigation plan was elaborated in order to characterize the environmental matrices there, and it provided for inspection of the zones (included in the valley of Gromolo stream) which, according to our preliminary studies and according to literature, could be most affected by past mining activity. Within our selected zones, some soils (even cultivated) were collected in order to check their contamination by heavy metals. Results from the analysis of the collected soil samples showed that the content of heavy metals often exceeds limits provided by the Italian Law 152/06. The knowledge of situation concerning pollution can give useful indications about the influence of mining activities on the surrounding environment, and it can also be valid support in order to organize an optimal future use of the studied mining area, which has been abandoned since its closure (1962).Web of Science23334533
Comparison of heavy-metal bioaccumulation properties in Pinus sp and Quercus sp in selected European Cu deposits
Heavy-metal contamination of Pinus pinaster, P. sylvestris, Quercus robur, and Q. rotundifolium was studied in four abandoned historic Cu deposits from Italy (Libiola, Caporciano), Portugal (Sao Domingos), and Slovakia (L'ubietova). The highest Cu and Mn contents in anthropogenic soil were described in Libiola and Caporciano whereas the highest Pb, Zn, As, and Sb contents in Sao Domingos. The anthropogenic soil in L'ubietova shows the highest Co contents. The area of Sao Domingos is the most acidified. There are important differences between the bioaccumulation of plants from individual deposits. Bioavailability of the heavy metals is generally independent of the pH values. The high Ca and Mg contents in soil are able to block the transport of heavy metals to the plant tissues. The bioconcentration factor values of all plant taxa, in all deposits, indicate a predominant strategy of excluders. Only Ag shows excellent bioconcentration ability. In L'ubietova, Pinus sylvestris has a strategy as an accumulator of Pb (2.43) and Zn (2.49); Pinus pinaster of Mn (4.97), Cd (1.85), and Co (5.62) and Quercus rotundifolium of Mn (3.54) in Sao Domingos. The predominantly low translocation factor values indicate that in most cases the heavy metals are accumulated in roots; only in a few rare cases do they migrate to shoots (e.g. Zn in Pinus sp. from all localities, Co in P. pinaster in Sao Domingos).Web of Science16878
Hazards of Heavy Metal Contamination at L’ubietová Cu-Deposit (Slovakia)
AbstractThe dump-fields Podlipa and Reiner at L’ubietová abandoned Cu-(Ag) deposit is situated at the boundary of the village settlement. The heavy metal contamination of the technogenous sediments and soils at the investigated dump-field show irregular planar distribution. Also the heavy metal content in the surface water, drainage water and in the groundwater was studied both in the dry as well as during the rainy periods. The speciation of As and Sb showed that there are present both As3+, Sb3+ as well as the less toxic As5+ and Sb5+ species. In the sediments prevail As5+ and Sb5+ species while in the water is dominant the As3+ and Sb3+ form. The article also presents results of the plant tissue degradation study in heavy metal contaminated conditions and compares them with those from reference sites. The cementation process causes substitution of iron by copper. The technogenous sediments and the contaminated soil of the dump show only very limited acidification potential. The installation of the Fe0-barrier seems to an acceptable solution for cleaning of the underground water
Coronary artery perforation: How to treat it?
AbstractCoronary artery perforation fortunately represents a rare complication of coronary catheterization but, if not properly and promptly treated, it is burdened by a high mortality rate. Rates of coronary perforation may be potentially higher when atherectomy devices are used or very complex calcified lesions are treated. Cardiac tamponade constitutes the most severe clinical consequence.We report the case of an intra-stent coronary perforation at the end of revascularization of a non-ST elevation myocardial infarction (NSTEMI), followed by an immediate impairment of hemodynamic compensation, due to significant pericardial effusion and subsequent cardiac tamponade.The use of covered stents has revolutionized the management of coronary perforation and this has meant that the use of emergency CABG has decreased over the years with satisfactory immediate and short-term outcomes, reducing the incidence of acute cardiac tamponade and mortality without surgery
Comparison of soil contamination at the selected European copper mines
ABSTRACT: This article reports the results of a study concerning contamination of the dump-fields by potentially toxic elements at five abandoned copper mines: Ľubietová, Špania Dolina (Slovakia), Libiola, Caporciano (Italy) and São Domingos (Portugal). This paper offers an updated description of soil contamination at the individual deposits and indicates a possible solution of the derived environmental problems. Contamination of technosoils by PTEs at the dump-fields shows an irregular spatial distribution of Fe, Cr, Mn, Co, Ni, Cu, Zn, As, Cd, Sb and Pb. Contents of PTEs often exceed both national and EU law limits. Whereas at Ľubietová, Špania Dolina and Caporciano the environmental risk is limited, at Libiola and São Domingos it seems to be very heavy. The technosoil (slag) of the dump-fields is not well aerated and the soil colloids have (except for Špania Dolina) negative surface charge, so they are suitable for PTEs sorption. The main environmental risk in the mining area of Sao Domingos district is the long time formation of acid mine drainage water and the high Zn, As and Pb contents. The release of PTEs to the environmental components may be limited by phytostabilization and immobilization of metals, by suitable admixtures into the technosoil/slag. The environmental situation at Caporciano is not so compromised as at São Domingos mining area. Phytostabilization will be able to stop erosion, and installation of wetlands under the dump will stop the release of Cu to the environment.info:eu-repo/semantics/publishedVersio
Percutaneous Edge-to-Edge Mitral Valve Repair with the Mitraclip System in Barlow's Disease
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