Resonant tunneling through a small quantum dot coupled to superconducting leads

We address the problem of non-linear transport through discrete electronic levels in a small quantum dot coupled to superconducting electrodes. In our approach the low temperature I-V characteristics can be calculated including all multiple quasi-particle and Andreev processes. The limit of very weak coupling to the leads and large charging energies is briefly analyzed comparing the calculated lineshapes of the I-V curves with recent experimental results. When the coupling to the leads increases and Coulomb blockade effects can be neglected, the combination of multiple Andreev processes and resonant transmission gives rise to a rich subgap structure which largely differs from the one found in the more studied S-N-S systems. We show how multiple processes can be included within a simple sequential tunneling picture qualitatively explaining the subgap structure. We suggest an experimental set-up where the predicted effects could be observed.Comment: 11 pages, 4 postscript figures, to be published in Phys. Rev. B (rapid communications

Density-Matrix functional theory of strongly-correlated lattice fermions

A density functional theory (DFT) of lattice fermion models is presented, which uses the single-particle density matrix gamma_{ij} as basic variable. A simple, explicit approximation to the interaction-energy functional W[gamma] of the Hubbard model is derived from exact dimer results, scaling properties of W[gamma] and known limits. Systematic tests on the one-dimensional chain show a remarkable agreement with theBethe-Ansatz exact solution for all interaction regimes and band fillings. New results are obtained for the ground-state energyand charge-excitation gap in two dimensions. A successful description of strong electron correlations within DFT is achieved.Comment: 15 pages, 6 figures Submitted to PR

Interaction energy functional for lattice density functional theory: Applications to one-, two- and three-dimensional Hubbard models

The Hubbard model is investigated in the framework of lattice density functional theory (LDFT). The single-particle density matrix $\gamma_{ij}$ with respect the lattice sites is considered as the basic variable of the many-body problem. A new approximation to the interaction-energy functional $W[\gamma]$ is proposed which is based on its scaling properties and which recovers exactly the limit of strong electron correlations at half-band filling. In this way, a more accurate description of $W$ is obtained throughout the domain of representability of $\gamma_{ij}$, including the crossover from weak to strong correlations. As examples of applications results are given for the ground-state energy, charge-excitation gap, and charge susceptibility of the Hubbard model in one-, two-, and three-dimensional lattices. The performance of the method is demonstrated by comparison with available exact solutions, with numerical calculations, and with LDFT using a simpler dimer ansatz for $W$. Goals and limitations of the different approximations are discussed.Comment: 25 pages and 8 figures, submitted to Phys. Rev.

Density-matrix functional theory of the Hubbard model: An exact numerical study

A density functional theory for many-body lattice models is considered in which the single-particle density matrix is the basic variable. Eigenvalue equations are derived for solving Levy's constrained search of the interaction energy functional W, which is expressed as the sum of Hartree-Fock energy and the correlation energy E_C. Exact results are obtained for E_C of the Hubbard model on various periodic lattices. The functional dependence of E_C is analyzed by varying the number of sites, band filling and lattice structure. The infinite one-dimensional chain and one-, two-, or three-dimensional finite clusters with periodic boundary conditions are considered. The properties of E_C are discussed in the limits of weak and strong electronic correlations, as well as in the crossover region. Using an appropriate scaling we observe a pseudo-universal behavior which suggests that the correlation energy of extended systems could be obtained quite accurately from finite cluster calculations. Finally, the behavior of E_C for repulsive (U>0) and attractive (U<0) interactions are contrasted.Comment: Phys. Rev. B (1999), in pres

Fate of anthropogenic radionuclides (90Sr, 137Cs, 238Pu, 239Pu, 240Pu, 241Am) in seawater in the northern Benguela upwelling system off Namibia

A baseline study on anthropogenic radioactivity in the Namibian marine ecosystem, which is part of the northern Benguela upwelling system, known as one of the most productive ocean areas in the world, has been performed. A scientific cruise carried out in 2014 covering inshore and offshore areas, exhibiting different oceanographic features, has provided a basis for better understanding the distributions, ratios and inventories of six anthropogenic radionuclides (Sr, Cs, Pu, Pu, Pu and Am) in seawater. Although H was also measured, due to extremely low levels, its behaviour was not studied. The main source of Sr, Cs, Pu, Pu and Am in the samples analysed was proven to be global fallout, a finding further confirmed by Pu/Pu and Sr/Cs ratios. Furthermore, the Pu SNAP-9A satellite accident signal was confirmed once again through the determination of the Pu/Pu activity ratio. Inshore and offshore samples showed different patterns due to the unique oceanographic features of this upwelling system. The levels of anthropogenic radionuclides, comprehensively assessed for the first time in this region, are comparable with the few existing data and filled a critical gap for the Southern Atlantic Ocean.This work has been partly financed through the project PGC 2018-094546-B-I00 provided by the Spanish Government (Ministerio de Ciencia, Innovación y Universidades)

Circulating Tumor Cells and Biomarker Modulation with Olaratumab Monotherapy Followed by Olaratumab plus Doxorubicin: Phase Ib Study in Patients with Soft-Tissue Sarcoma

This phase Ib study enumerated whole blood circulating tumor cells (CTC) and evaluated biomarkers in patients with potentially resectable soft-tissue sarcoma (STS) treated with olaratumab monotherapy (20 mg/kg) for one cycle followed by up to six cycles of olaratumab (20 mg/kg, cycles 1–2; 15 mg/kg, cycles 3–7) plus doxorubicin (75 mg/m2 on day 1). CTCs, platelet-derived growth factor receptors (PDGFR), and PDGF ligand expression in tumor tissue pre- and post-olaratumab monotherapy were evaluated. Antitumor activity, safety, pharmacokinetics, and PET/biomarker association with clinical outcome were assessed. Of 51 treated patients, 35, 43, and 37 were evaluable for CTC enumeration, PDGFRs, and PDGF ligand expression, respectively. An increase in CTCs at cycle 1 day 8 was observed, followed by a significant reduction by cycle 3 day 1 or 30-day follow-up. Decrease in CTC counts after olaratumab monotherapy was higher in patients with disease control than without disease control (57.9% vs. 31.2%). Baseline IHC expression was positive in most patients for PDGFRα [n = 31 (72.1%)] and PDGFRβ [n = 36 (83.7%)]. Similar rates were observed post-olaratumab monotherapy [PDGFRα, n = 30 (69.8%); PDGFRβ, n = 33 (76.7%)]. Eleven patients (29.7%) showed a 30% reduction by RT-PCR in PDGFRα at cycle 2. PDGFR expression and PET response showed no correlation with clinical outcome. Safety and pharmacokinetic profiles were consistent with previous reports. This study, the first to use a validated method for CTC detection, confirms that CTC enumeration in STS is feasible. However, no correlation was observed between PDGFRα expression and clinical outcome.This work was supported by Eli Lilly and Company

Generic competences for the IT knowledge workers: a study from the field.

Proceedings of: Third World Summit on the Knowledge Society (WSKS 2010), Corfu, Greece, September 22-24, 2010This paper aims to identify generic competency levels relevant to a particular kind of knowledge workers: software engineers. Based on previous works, and in particular in the description of a professional career, authors review of the literature related to the characterization of the labor force in the Software Engineering (SE) domain. Subsequently, using a quantitative analysis based on investigative surveys administered to a number of representative professionals, authors provide with a generic competency ladder adapted to the given career description.Publicad

Introduction revisiting the Argentine crisis a decade on: changes and continuities

This introductory chapter to the book "Argentina Since the 2001 Crisis Recovering the Past, Reclaiming the Future" analyses crisis and its associated responses and subsequent recovery in the context of Argentina’s multiple implosion of 2001-02 whilst also assessing its legacies for the country’s social, cultural, economic and political realms during the last decade. It recognises that "crisis" is a term that is much used in the post-Lehman Brothers world and that the subsequent responses and associated recoveries (or lack of) have been the subject of a cascade of academic, government, media, and think-tank investigation ever since. The chapter instead seeks to understand the nature of how crisis and its impacts should be investigated and interrogated, by rejecting false dichotomies of ‘old’ and ‘new’ and synthesising understanding to form an analysis that draws both elements of continuity and elements of change. Secondly, it argues that crisis manifests itself in a number of realms, and that heuristic devices employed to investigate them must subsequently also be drawn from across a range of disciplinary perspectives. Thirdly, it examines how the 2001-02 crisis in Argentina led to a series of responses that both rejected the neoliberal model yet also recovered elements of it. Finally it outlines the structure of the rest of the book, briefly summarising the chapters in turn

Projected sensitivity of the LUX-ZEPLIN experiment to the 0νββ decay of Xe 136

The LUX-ZEPLIN (LZ) experiment will enable a neutrinoless double β decay search in parallel to the main science goal of discovering dark matter particle interactions. We report the expected LZ sensitivity to Xe136 neutrinoless double β decay, taking advantage of the significant (&gt;600 kg) Xe136 mass contained within the active volume of LZ without isotopic enrichment. After 1000 live-days, the median exclusion sensitivity to the half-life of Xe136 is projected to be 1.06×1026 years (90% confidence level), similar to existing constraints. We also report the expected sensitivity of a possible subsequent dedicated exposure using 90% enrichment with Xe136 at 1.06×1027 years