Zero-temperature Phase Diagram of Two Dimensional Hubbard Model

We investigate the two-dimensional Hubbard model on the triangular lattice with anisotropic hopping integrals at half filling. By means of a self-energy functional approach, we discuss how stable the non-magnetic state is against magnetically ordered states in the system. We present the zero-temperature phase diagram, where the normal metallic state competes with magnetically ordered states with $(\pi, \pi)$ and $(2\pi/3, 2\pi/3)$ structures. It is shown that a non-magnetic Mott insulating state is not realized as the ground state, in the present framework, but as a meta-stable state near the magnetically ordered phase with $(2\pi/3, 2\pi/3)$ structure.Comment: 4 pages, 4 figure

Phytohaemagglutinin on maternal and umbilical leukocytes

Almost all the umbilical lymphocytes showed more extensive blast cell formation than that of their mother's lymphocytes with PHA. Pathological conditions of mother in pregnancy and labor such as anemia, gestational toxicosis, difficult labor and asphyxia of babies, inhibited the normal response of both maternal and umbilical lymphocytes to PHA.</p

Magnetic systems at criticality: different signatures of scaling

Different aspects of critical behaviour of magnetic materials are presented and discussed. The scaling ideas are shown to arise in the context of purely magnetic properties as well as in that of thermal properties as demonstrated by magnetocaloric effect or combined scaling of excess entropy and order parameter. Two non-standard approaches to scaling phenomena are described. The presented concepts are exemplified by experimental data gathered on four representatives of molecular magnets.Comment: 33 pages, 16 figure

Tissue specific induction of p62/sqstm1 by farnesoid X receptor

Background: Farnesoid X Receptor (FXR) is a member of the nuclear receptor superfamily and is a ligand-activated transcription factor essential for maintaining liver and intestinal homeostasis. FXR is protective against carcinogenesis and inflammation in liver and intestine as demonstrated by the development of inflammation and tumors in the liver and intestine of FXR knock-out mice. However, mechanisms for the protective effects of FXR are not completely understood. This study reports a novel role of FXR in regulating expression of Sqstm1, which encodes for p62 protein. p62 plays an important role in maintaining cellular homeostasis through selective autophagy and activating signal transduction pathways, such as NF-κB to support cell survival and caspase-8 to initiate apoptosis. FXR regulation of Sqstm1 may serve as a protective mechanism. Methods and Results: This study showed that FXR bound to the Sqstm1 gene in both mouse livers and ileums as determined by chromatin immunoprecipitation. In addition, FXR activation enhanced transcriptional activation of Sqstm1 in vitro. However, wild-type mice treated with GW4064, a synthetic FXR ligand, showed that FXR activation induced mRNA and protein expression of Sqstm1/p62 in ileum, but not in liver. Interestingly, FXR-transgenic mice showed induced mRNA expression of Sqstm1 in both liver and ileum compared to wild-type mice. Conclusions: Our current study has identified a novel role of FXR in regulating the expression of p62, a key factor in protein degradation and cell signaling. Regulation of p62 by FXR indicates tissue-specific and gene-dosage effects. Furthermore, FXR-mediated induction of p62 may implicate a protective mechanism of FXR. © 2012 Williams et al

Finite-temperature Mott transitions in multi-orbital Hubbard model

We investigate the Mott transitions in the multi-orbital Hubbard model at half-filling by means of the self-energy functional approach. The phase diagrams are obtained at finite temperatures for the Hubbard model with up to four-fold degenerate bands. We discuss how the first-order Mott transition points $U_{c1}$ and $U_{c2}$ as well as the critical temperature $T_c$ depend on the orbital degeneracy. It is elucidated that enhanced orbital fluctuations play a key role to control the Mott transitions in the multi-orbital Hubbard model.Comment: 8 pages, 7 figure

Metal-insulator transition in the two-orbital Hubbard model at fractional band fillings: Self-energy functional approach

We investigate the infinite-dimensional two-orbital Hubbard model at arbitrary band fillings. By means of the self-energy functional approach, we discuss the stability of the metallic state in the systems with same and different bandwidths. It is found that the Mott insulating phases are realized at commensurate band fillings. Furthermore, it is clarified that the orbital selective Mott phase with one orbital localized and the other itinerant is stabilized even at fractional band fillings in the system with different bandwidths.Comment: 7 pages, 10 figure

Simultaneous formation of Solar System giant planets

In the last few years, the so-called "Nice model" has got a significant importance in the study of the formation and evolution of the solar system. According to this model, the initial orbital configuration of the giant planets was much more compact than the one we observe today. We study the formation of the giant planets in connection with some parameters that describe the protoplanetary disk. The aim of this study is to establish the conditions that favor their simultaneous formation in line with the initial configuration proposed by the Nice model. We focus in the conditions that lead to the simultaneous formation of two massive cores, corresponding to Jupiter and Saturn, able to achieve the cross-over mass (where the mass of the envelope of the giant planet equals the mass of the core, and gaseous runway starts) while Uranus and Neptune have to be able to grow to their current masses. We compute the in situ planetary formation, employing the numerical code introduced in our previous work, for different density profiles of the protoplanetary disk. Planetesimal migration is taken into account and planetesimals are considered to follow a size distribution between $r_p^{min}$ (free parameter) and $r_p^{max}= 100$ km. The core's growth is computed according to the oligarchic growth regime. The simultaneous formation of the giant planets was successfully completed for several initial conditions of the disk. We find that for protoplanetary disks characterized by a power law ($\Sigma \propto r^{-p}$), smooth surface density profiles ($p \leq 1.5$) favor the simultaneous formation. However, for steep slopes ($p\sim 2$, as previously proposed by other authors) the simultaneous formation of the solar system giant planets is unlikely ...Comment: Accepted for publication in Astronomy and Astrophysic

Calculation of the average Green's function of electrons in a stochastic medium via higher-dimensional bosonization

The disorder averaged single-particle Green's function of electrons subject to a time-dependent random potential with long-range spatial correlations is calculated by means of bosonization in arbitrary dimensions. For static disorder our method is equivalent with conventional perturbation theory based on the lowest order Born approximation. For dynamic disorder, however, we obtain a new non-perturbative expression for the average Green's function. Bosonization also provides a solid microscopic basis for the description of the quantum dynamics of an interacting many-body system via an effective stochastic model with Gaussian probability distribution.Comment: RevTex, no figure