Strictly correlated uniform electron droplets

We study the energetic properties of finite but internally homogeneous D-dimensional electron droplets in the strict-correlation limit. The indirect Coulomb interaction is found to increase as a function of the electron number, approaching the tighter forms of the Lieb-Oxford bound recently proposed by Rasanen et al. [Phys. Rev. Lett. 102, 206406 (2009)]. The bound is satisfied in three-, two-, and one-dimensional droplets, and in the latter case it is reached exactly - regardless of the type of interaction considered. Our results provide useful reference data for delocalized strongly correlated systems, and they can be used in the development and testing of exchange-correlation density functionals in the framework of density-functional theory

Condensation in an Economic Model with Brand Competition

We present a linear agent based model on brand competition. Each agent belongs to one of the two brands and interacts with its nearest neighbors. In the process the agent can decide to change to the other brand if the move is beneficial. The numerical simulations show that the systems always condenses into a state when all agents belong to a single brand. We study the condensation times for different parameters of the model and the influence of different mechanisms to avoid condensation, like anti monopoly rules and brand fidelity.Comment: Accepted in: International Journal of Modern Physics

Comportament de la taxa de multiplicació al llarg de successius subcultius, atenent l'època d'explantació, de C. Scolymus cv. "Blanca de Tudela"

Peer Reviewe

Magnetically-textured superconductivity in elemental Rhenium

Recent μSR measurements revealed remarkable signatures of spontaneous magnetism coexisting with superconductivity in elemental rhenium. Here we provide a quantitative theory that uncovers the nature of the superconducting instability by incorporating every details of the electronic structure together with spin-orbit coupling and multi-orbital physics. We show that conventional s-wave superconductivity combined with strong spin-orbit coupling is inducing even-parity odd-orbital spin triplet Cooper pairs, and in presence of a screw axis Cooper pairs’ migration between the induced equal-spin triplet component leads to an exotic magnetic state

TGF-β and MMPs: A complex regulatory loop involved in tumor progression

Transforming growth factor-β (TGF-β) has a dual and contradictory role in cancer. It is a tumor suppressor at early stages of tumor formation by virtue of its growth inhibitory and pro-apoptotic functions. However, at later stages of tumor progression, tumor cells lose their sensitivity to be growth inhibited by this cytokine, and, then, TGF-β facilitates tumor invasion and metastasis by diverse mechanisms, including the induction of an epithelial-mesenchymal transition, the suppression of the immune system and the stimulation of angiogenesis. Matrix metalloproteinases (MMPs) have also been shown to play a pivotal function in tumor cell migration, invasion and angiogenesis. MMPs and TGF-β form an interplay loop that may attenuate or promote tumor progression. On one hand, latent TGF-β, an inactive TGF-β precursor that is sequestered by the extracellular matrix, is proteolytically activated by MMPs; the released active cytokine may, then, suppress or promote tumor cell growth and invasiveness depending on the tumor stage. On the other hand, TGF-β regulates the expression of MMPs and their tissue inhibitors TIMPs in both tumor and stromal cells. MMPs in the tumor microenvironment are involved in the control of tumor cell growth and survival by modulating the bioavailability of growth factors and chemokines, and they also influence inflammation and angiogenesis. Thus, by modulating the net balance of MMPs and TIMPs in both compartments: the tumor and stroma, TGF-β regulates malignant progression.The work developed in our laboratories is supported by grants of the Spanish Ministry of Science and Innovation (grant SAF2010-19152 to MQ) and the Ministry of Science and Technological Development of the Republic of Serbia (grant 175062 to JFS and JK). GC is the recipient of a contract from the Juan de la Cierva program of the Spanish Ministry of Science and Innovation.Peer Reviewe

Ultracold Gases of Ytterbium: Ferromagnetism and Mott States in an SU(6) Fermi System

It is argued that ultracold quantum degenerate gas of ytterbium $^{173}$Yb atoms having nuclear spin $I = 5/2$ exhibits an enlarged SU$(6)$ symmetry. Within the Landau Fermi liquid theory, stability criteria against Fermi liquid (Pomeranchuk) instabilities in the spin channel are considered. Focusing on the SU$(n > 2)$ generalizations of ferromagnetism, it is shown within mean-field theory that the transition from the paramagnet to the itinerant ferromagnet is generically first order. On symmetry grounds, general SU$(n)$ itinerant ferromagnetic ground states and their topological excitations are also discussed. These SU$(n > 2)$ ferromagnets can become stable by increasing the scattering length using optical methods or in an optical lattice. However, in an optical lattice at current experimental temperatures, Mott states with different filling are expected to coexist in the same trap, as obtained from a calculation based on the SU$(6)$ Hubbard model.Comment: 4+ pages, 1 figure; v2: Improved discussion of the SU(6) symmetry-breaking patterns; v3: added further discussion on the order of the transition. Added Reference

Immunocytochemical demonstration of p21 ras family oncogene product in normal mucosa and in premalignant and malignant tumours of the colorectum.

Study of the distribution of the p21 ras oncogene product as demonstrated by monoclonal antibody Y13-259 shows this protein to be apparently present in all epithelial populations of both premalignant and malignant tumours and throughout the normal foetal and adult epithelial crypt population in the colorectum. Metastatic tumour in liver shows a similar staining pattern which is less intense however than in the surrounding normal hepatocytes. Our results suggest that the presence of this protein is a widespread feature of normal cellular metabolism in certain cell types and is not restricted to those actively involved in cellular proliferation. It appears, furthermore, that neither cells at different stages of carcinogenesis nor those representing variants of a malignant phenotype can be identified using this particular antibody

A methodology to implement a closed-loop feedback-feedforward level control in a laboratory-scale flotation bank using peristaltic pumps

This paper describes the implementation of a level control strategy in a laboratory-scale flotation system. The laboratory-scale system consists of a bank of three flotation tanks connected in series, which mimics a flotation system found in mineral processing plants. Besides the classical feedback control strategy, we have also included a feedforward strategy to better account for process disturbances. Results revealed that the level control performance significantly improves when a feedforward strategy is considered. This methodology uses peristaltic pumps for level control, which has not been extensively documented even though: (1) peristaltic pumps are commonly used in laboratory-scale systems, and (2) the control implementation is not as straightforward as those control strategies that use valves. Therefore, we believe that this paper, which describes a proven methodology that has been validated in an experimental system, can be a useful reference for many researchers in the field.•Preparation of reagents to ensure that the froth stability of the froth layer is representative of an industrial flotation froth.•Calibration of instruments - convert the electrical signal from PLCs to engineering units.•Tuning PI parameters using SIMC rules by performing step-changes in each flotation cell