80 research outputs found
Combined SMEFT interpretation of Higgs, diboson, and top quark data from the LHC
No full textWe present a global interpretation of Higgs, diboson, and top quark production and decay measurements from the LHC in the framework of the Standard Model Effective Field Theory (SMEFT) at dimension six. We constrain simultaneously 36 independent directions in its parameter space, and compare the outcome of the global analysis with that from individual and two-parameter fits. Our results are obtained by means of state-of-the-art theoretical calculations for the SM and the EFT cross-sections, and account for both linear and quadratic corrections in the 1/Λ2 expansion. We demonstrate how the inclusion of NLO QCD and O(Λ−4) effects is instrumental to accurately map the posterior distributions associated to the fitted Wilson coefficients. We assess the interplay and complementarity between the top quark, Higgs, and diboson measurements, deploy a variety of statistical estimators to quantify the impact of each dataset in the parameter space, and carry out fits in BSM-inspired scenarios such as the top-philic model. Our results represent a stepping stone in the ongoing program of model-independent searches at the LHC from precision measurements, and pave the way towards yet more global SMEFT interpretations extended to other high-pT processes as well as to low-energy observables. [Figure not available: see fulltext.
The utility of the transtubular potassium gradient in the evaluation of hyperkalemia
No full textThe transtubular potassium gradient (TTKG) is used to gauge renal potassium secretion by the cortical collecting duct, indirectly assessing mineralocorticoid bioactivity in patients who have hypo- or hyperkalemia. TTKG values 6 indicate an inappropriate renal response to hyperkalemia, whereas values 2 during hypokalemia point to renal loss. Hypokalemia is not addressed here. Studies supporting the usefulness of the TTKG in hyperkalemia are limited to case series. This calculation may be most useful in distinguishing hyperkalemic patients who have mineralocorticoid deficiency versus resistance by observing a change in TTKG values after physiologic or pharmacologic doses of mineralocorticoids. Copyright © 2008 by the American Society of Nephrology.CHOI MJ, 1993, NEW ENGL J MED, V328, P703, DOI 10.1056-NEJM199303113281006; ETHIER JH, 1990, AM J KIDNEY DIS, V15, P309; FIELD MJ, 1984, KIDNEY INT, V25, P502, DOI 10.1038-ki.1984.46; GOOD VW, 1984, AM J PHYSIOL, V254, pF609; KAMEL KS, 1990, AM J NEPHROL, V10, P89, DOI 10.1159-000168062; KAMEL KS, 1992, J AM SOC NEPHROL, V2, P1279; LAINE J, 1995, EUR J CLIN INVEST, V25, P670, DOI 10.1111-j.1365-2362.1995.tb01984.x; Lim YS, 2002, LIVER, V22, P426, DOI 10.1034-j.1600-0676.2001.01693.x; Mayan H, 2001, NEPHRON, V89, P56, DOI 10.1159-000046044; RODRIGUEZSORIANO J, 1990, PEDIATR NEPHROL, V4, P105; Weinstein AM, 2001, AM J PHYSIOL-RENAL, V280, pF1072; WEST ML, 1988, AM J NEPHROL, V8, P373, DOI 10.1159-000167620; WEST ML, 1986, MINER ELECTROL METAB, V12, P234; WEST ML, 1986, MINER ELECTROL METAB, V12, P226; ZETTLE RM, 1987, AM J NEPHROL, V7, P360, DOI 10.1159-00016750222151
Characterization of Glaucomatous Rat Eye Optic Nerve Head Biomechanics with Individual-Specific Finite Element Modeling
No full textGlaucoma is the leading cause of irreversible blindness and in 2040, more than 111 million people are expected to have the disease. Vision loss in glaucoma is caused by the death of retinal ganglion cells (RGCs) primarily in the optic nerve head (ONH). Elevated intraocular pressure (IOP) is a well-known causative risk factor for glaucoma, highlighting the importance of biomechanics in the disease. All current therapies are focused on lowering IOP levels. However, these therapies are not effective for all patients. One limiting factor in the search for new therapies is the lack of knowledge about the cell processes that lead from biomechanical insult to RGC apoptosis. To better understand this relationship, animal models are used and amongst these models, rats are widely-used due to their pathophysiological similarities to human glaucoma. However, there are anatomical differences between the rat and human ONH, and these differences are likely to affect rat ONH biomechanics. Moreover, there are some anatomical alterations occur in the rat ONH due to remodeling and damage in the early stages of the disease. Computational modeling is a suitable approach for characterizing ONH biomechanics due to the complex anatomy of the posterior rat eye and there has been no previous attempt to characterize the glaucomatous rat eye ONH biomechanics. The aim of this thesis is to characterize glaucomatous rat ONH biomechanics by building two individual-specific glaucomatous rat ONH finite element models (FEMs). By comparing the 1st (mean and the 95th percentile) and 3rd (mean and the 5th percentile) principal strains on the anterior ON with previously built healthy rat eye individual-specific FEMs, the effect of geometrical differences occurred due to remodeling and damage in the early stages of the glaucoma were aimed to be better understood. The 1st principal strain (mean and 95th percentile) relative percentage differences between the glaucomatous and healthy rat eyes under the IOP of 30mmHg were found to be 37.74% and 69.66% for the MR04, and 35.66% and 66.02% for the MR05 rats. The 3rd principal strain (mean and 5th percentile) relative percentage differences were found to be 12.28% and 35.23% for the MR04, and 10.31% and 11.05% for the MR05 rats, in which the glaucomatous rat eyes had higher magnitude strains. When the experimentally measured mean IOP values were applied to the glaucomatous rat eye models, these calculated relative percentage differences were increased. Moreover, when the strain patterns in the anterior ON were observed, larger strains were located in the inferior ON in both of the glaucomatous rat eyes. Thus, the localization of high strain patterns observed in this study for the glaucomatous eyes were similar to the healthy rat eyes, which were dominantly located at the inferior ON. However, the magnitudes of the principal strains in the glaucomatous rat eye anterior ON were elevated due to the geometrical differences caused by remodeling and damage during the early stages of the disease.Biomedical Engineering | Tissue Biomechanics and Implant
Parton distributions in nucleons and nuclei
No full textWe review the current status of parton distribution function (PDF) determinations for unpolarized and longitudinally polarized protons and for unpolarized nuclei, which are probed by high-energy hadronic scattering in perturbative quantum chromodynamics (QCD).We present the established theoretical framework, the experimental information, and the methodological aspects inherent to any modern PDF extraction. Furthermore, we summarize the present knowledge of PDFs and discuss their limitations in both accuracy and precision relevant to advancing our understanding of QCD proton substructure and pursuing our quest for precision in the Standard Model and beyond. In this respect, we highlight various achievements, discuss contemporary issues in PDF analyses, and outline future directions of progress.</p
Exchange Rate Dynamics and the Overshooting Hypothesis
No full textIn this paper we analyze the determinants of the evolution of ex- change rates within the context of alternative models of exchange rate dynamics. We examine the overshooting hypothesis in models which emphasize differential speeds of adjustment in asset and goods markets as well as in models which emphasize portfolio balance considerations. We show that exchange rate overshooting is not an intrinsic characteristic of the foreign exchange market and that it depends on a set of specific assumptions. We also show that the overshooting is not a characteristic of the assumption of perfect foresight nor does it depend in general on the assumption that goods and asset markets clear at different speeds. As long as the speeds of adjustment in the various markets are less than infinite, the key factor determining the short run effects of a monetary expansion is the degree of capital mobility. When capital is highly mobile, the exchange rate overshoots its long-run value and when capital is relatively immobile the exchange rate undershoots its long-run value. Within the context of the portfolio-balance model we show that the effects of a monetary expansion on the dynamics of exchange rates and in particular on whether exchange rates overshoot or undershoot their equilibrium path depend critically on the specification of asset choice, on the degree of substitution among assets, and on the quality of the various assets in being an inflation hedge, Specifically, when internationally traded goods are a better inflation hedge than nontraded goods, the nominal exchange rate overshoots the domestic price level and conversely.
Criação e desvio de comércio no Mercosul: período de 1991 a 2000
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Sócio-Econômico. Programa de Pós-Graduação em Economia
Trade liberalisation and regional integration: the search for large numbers
No full textWe surveyed the empirical literature using multi-country computable general equilibrium (CGE) models to analyse potential and actual regional trade agreements (RTAs). The studies indicate that these RTAs improve welfare, that trade creation greatly exceeds trade diversion, and that they are consistent with further global liberalisation. The welfare gains are bigger when models incorporate aspects of ‘‘new trade theory’’ such as increasing returns, imperfect competition, and links between trade liberalisation, total factor productivity growth, and capital accumulation. We also conjectured that an RTA expands market size and stability, allowing firms to pursue economies of fine specialisation, generating additional ‘‘Smithian’’ efficiency gains.International Relations/Trade,
SMEFT analysis of vector boson scattering and diboson data from the LHC Run II
No full textWe present a systematic interpretation of vector boson scattering (VBS) and diboson measurements from the LHC in the framework of the dimension-six standard model effective field theory (SMEFT). We consider all available measurements of VBS fiducial cross-sections and differential distributions from ATLAS and CMS, in most cases based on the full Run II luminosity, and use them to constrain 16 independent directions in the dimension-six EFT parameter space. Compared to the diboson measurements, we find that VBS provides complementary information on several of the operators relevant for the description of the electroweak sector. We also quantify the ultimate EFT reach of VBS measurements via dedicated projections for the high luminosity LHC. Our results motivate the integration of VBS processes in future global SMEFT interpretations of particle physics data
Nuclear parton distributions from lepton-nucleus scattering and the impact of an electron-ion collider: NNPDF Collaboration
No full textWe present a first determination of the nuclear parton distribution functions (nPDF) based on the NNPDF methodology: nNNPDF1.0. This analysis is based on neutral-current deep-inelastic structure function data and is performed up to NNLO in QCD calculations with heavy quark mass effects. For the first time in the NNPDF fits, the χ2 minimization is achieved using stochastic gradient descent with reverse-mode automatic differentiation (backpropagation). We validate the robustness of the fitting methodology through closure tests, assess the perturbative stability of the resulting nPDFs, and compare them with other recent analyses. The nNNPDF1.0 distributions satisfy the boundary condition whereby the NNPDF3.1 proton PDF central values and uncertainties are reproduced at A= 1 , which introduces important constraints particularly for low-A nuclei. We also investigate the information that would be provided by an Electron-Ion Collider (EIC), finding that EIC measurements would significantly constrain the nPDFs down to x≃ 5 × 10 - 4. Our results represent the first-ever nPDF determination obtained using a Monte Carlo methodology consistent with that of state-of-the-art proton PDF fits, and provide the foundation for a subsequent global nPDF analyses including also proton-nucleus data
National competitiveness and absolute advantage in a global economy
No full textDistinguished trade theorists maintain that a national economy cannot be uncompetitive as a whole, contrary to the frequent statements of many politicians, because a country must possess a comparative advantage in some sector according to Ricardo’s principle. In this paper the author arguesthat such a criticism addressed to the notion of national competitiveness neglects a bottom line of a national economy engaged in a global market. In this context, characterized by free capital movements and possible unemployment, absolute productivity and absolute advantage may prevail over relative productivity and comparative advantage and can affect the competitiveness of all productive sectors of a single country. Such a reappraisal of international equilibrium offers a theoretical foundation to the intuitive idea that national competitiveness can be a source of possible economic conflict among the national members of a global economy. Final version of this working paper : S. Parrinello, “ The notion of national competitiveness in a global economy” chapter 4, pp. 49-68, in Economic Theory and Economic Thought, Essays in Honour of Ian Steedman, J. Vint, J. Metcalfe, H. Kurz, N. Salvadori and P.A. Samuelson (eds.). London and New Yor)k: Routledge, 2010.National competitiveness, Globalization, International Trade
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