Correlation-Driven Charge and Spin Fluctuations in LaCoO_{3}.

The spin transition in LaCoO_{3} has been investigated using density-functional theory in combination with dynamical mean-field theory employing continuous time quantum Monte Carlo and exact diagonalization impurity solvers. Calculations on the experimental rhombohedral atomic structure with two Co sites per unit cell show that an independent treatment of the Co atoms results in a ground state with strong charge fluctuations induced by electronic correlations. Each atom shows a contribution from either a d^{5} or a d^{7} state in addition to the main d^{6} state. These states play a relevant role in the spin transition which can be understood as a low spin-high spin (LS-HS) transition with significant contributions (~10%) to the LS and HS states of d^{5} and d^{7} states, respectively. We report spectra as well as optical conductivity data for all cases. A thermodynamic analysis reveals a significant kinetic energy gain through introduction of charge fluctuations, which in addition to the potential energy reduction lowers the total energy of the system.

Excitation spectra of transition-metal atoms on the Ag (100) surface controlled by Hund's exchange.

We report photoemission experiments revealing the valence electron spectral function of Mn, Fe, Co, and Ni atoms on the Ag (100) surface. The series of spectra shows splittings of higher energy features which decrease with the filling of the 3d shell and a highly nonmonotonic evolution of spectral weight near the Fermi edge. First principles calculations demonstrate that two manifestations of Hund's exchange J are responsible for this evolution. First, there is a monotonic reduction of the effective exchange splittings with increasing filling of the 3d shell. Second, the amount of charge fluctuations and, thus, the weight of quasiparticle peaks at the Fermi level varies nonmonotonically through this 3d series due to a distinct occupancy dependence of effective charging energies U(eff).

Orbital Kondo effect in cobalt-benzene sandwich molecules.

We study a Co-benzene sandwich molecule bridging the tips of a Cu nanocontact as a realistic model of correlated molecular transport. To this end we employ a recently developed method for calculating the correlated electronic structure and transport properties of nanoscopic conductors. When the molecule is slightly compressed by the tips of the nanocontact the dynamic correlations originating from the strongly interacting Co 3d shell give rise to an orbital Kondo effect while the usual spin Kondo effect is suppressed due to Hund's rule coupling. This nontrivial Kondo effect produces a sharp and temperature-dependent Abrikosov-Suhl resonance in the spectral function at the Fermi level and a corresponding Fano line shape in the low bias conductance.

Spectral functions of isolated Ce adatoms on paramagnetic surfaces.

We report photoemission experiments revealing the full valence electron spectral function of Ce adatoms on Ag(111), W(110), and Rh(111) surfaces. A transfer of Ce 4f spectral weight from the ionization peak towards the Fermi level is demonstrated upon changing the substrate from Ag(111) to Rh(111). In the intermediate case of Ce on W(110) the ionization peak is found to be split. This evolution of the spectra is explained by means of first-principles theory, which clearly demonstrates that a reliable understanding of magnetic adatoms on metal surfaces requires simultaneous low and high energy spectroscopic information.

Nature of the Mott transition in Ca2RuO4.

We study the origin of the temperature-induced Mott transition in Ca2RuO4. As a method we use the local-density approximation+dynamical mean-field theory. We show the following. (i) The Mott transition is driven by the change in structure from long to short c-axis layered perovskite (L-Pbca→S-Pbca); it occurs together with orbital order, which follows, rather than produces, the structural transition. (ii) In the metallic L-Pbca phase the orbital polarization is ∼0. (iii) In the insulating S-Pbca phase the lower energy orbital, ∼xy, is full. (iv) The spin-flip and pair-hopping Coulomb terms reduce the effective masses in the metallic phase. Our results indicate that a similar scenario applies to Ca2-xSrxRuO4 (x≤0.2). In the metallic x≤0.5 structures electrons are progressively transferred to the xz/yz bands with increasing x; however, we find no orbital-selective Mott transition down to ∼300 K.

Local magnetic moments in iron and nickel at ambient and Earth's core conditions.

Some Bravais lattices have a particular geometry that can slow down the motion of Bloch electrons by pre-localization due to the band-structure properties. Another known source of electronic localization in solids is the Coulomb repulsion in partially filled d or f orbitals, which leads to the formation of local magnetic moments. The combination of these two effects is usually considered of little relevance to strongly correlated materials. Here we show that it represents, instead, the underlying physical mechanism in two of the most important ferromagnets: nickel and iron. In nickel, the van Hove singularity has an unexpected impact on the magnetism. As a result, the electron-electron scattering rate is linear in temperature, in violation of the conventional Landau theory of metals. This is true even at Earth's core pressures, at which iron is instead a good Fermi liquid. The importance of nickel in models of geomagnetism may have therefore to be reconsidered.

Effects of valence, geometry and electronic correlations on transport in transition metal benzene sandwich molecules.

We study the impact of the valence and the geometry on the electronic structure and transport properties of different transition metal-benzene sandwich molecules bridging the tips of a Cu nanocontact. Our density-functional calculations show that the electronic transport properties of the molecules depend strongly on the molecular geometry which can be controlled by the nanocontact tips. Depending on the valence of the transition metal center certain molecules can be tuned in and out of half-metallic behaviour facilitating potential spintronics applications. We also discuss our results in the framework of an Anderson impurity model, indicating cases where the inclusion of local correlations alters the ground state qualitatively. For Co and V centered molecules we find indications of an orbital Kondo effect.

TRIzol and Alu qPCR-based quantification of metastatic seeding within the skeleton.

Current methods for detecting disseminated tumor cells in the skeleton are limited by expense and technical complexity. We describe a simple and inexpensive method to quantify, with single cell sensitivity, human metastatic cancer in the mouse skeleton, concurrently with host gene expression, using TRIzol-based DNA/RNA extraction and Alu sequence qPCR amplification. This approach enables precise quantification of tumor cells and corresponding host gene expression during metastatic colonization in xenograft models.

The impact of the AFDC and Food Stamp programs on child nutrition: empirical evidence from New Orleans.

This study tests the hypotheses that the participation in the Aid to Families with Dependent Children (AFDC) and Food Stamp programs has a positive impact on children's nutritional status, after controlling for other potentially important household- and individual-level characteristics. The analysis is based on the responses of a health facility survey of 246 pairs of low-income mothers and children in New Orleans. The results indicate that participation in the AFDC and Food Stamp programs is associated with increased anthropometric status of children, but the foods consumed by children in families receiving welfare benefits were of significantly lower nutritional value than foods consumed by other children. Among the study's conclusions are the following: (1) in this low-income setting, AFDC and Food Stamp benefits are associated with higher food expenditures, higher anthropometric levels, but inferior diets, and (2) female-headed households spend more on food expenditures than other households, after controlling for other individual- and household-level characteristics.

General DFT++ method implemented with projector augmented waves: electronic structure of SrVO3 and the Mott transition in Ca(2-x)Sr(x)RuO4.

The realistic description of correlated electron systems took an important step forward a few years ago as the combination of density functional methods and dynamical mean-field theory was conceived. This framework allows access to both high and low energy physics and is capable of the description of the specific physics of strongly correlated materials, like the Mott metal-insulator transition. A very important step in the procedure is the interface between the band structure method and the dynamical mean-field theory and its impurity solver. We present a general interface between a projector augmented-wave-based density functional code and many-body methods based on Wannier functions obtained from a projection on local orbitals. The implementation is very flexible and allows for various applications. Quantities like the momentum-resolved spectral function are accessible. We present applications to SrVO(3) and the metal-insulator transition in Ca(2-x)Sr(x)RuO(4).

[Comparison of the effects of sodium fluoride and calcidiol on the remodeling of the endosteal surface of the rib cortex in dogs after administration of prednisone]. / Porównanie wplywu fluorku sodu i kalcidiolu na przebudowe powierzchni sródkostnej kory zeber psów otrzymujacych prednizon.

The effects were compared of sodium fluoride and calcidiol on the remodeling of the rib cortical-endosteal surface of dogs treated with prednisone for long time periods. The study used a histomorphometric and tetracycline labeling methods. It was found that administration of sodium fluoride with calcidiol and calcium carbonate limited in a higher degree than the treatment with calcidiol and calcium carbonate the development of the osteoporotic changes induced by glucocorticoids. This included reduced enhancement of the bone resorption surface, increased bone formation surface and osteoid thickness connected with acceleration of mineralization rate. The changes induced by sodium fluoride had a favorable effect on the ratio of the resorption to the formation process at the sites of bone remodeling.

Right renal vein extension technique in human kidney transplantation.

A technique for renal vein extension in right kidney transplantation is described. The use of this method allows to avoid some technical difficulties in the transplantation of kidneys with short renal vein and multiple arteries. The short renal vein, even in the presence of multiple arteries, should not by itself be regarded as a barrier to successful cadaveric kidney transplantation. By using all available kidneys for transplantation, regardless of the type of anatomical abnormalities, we were able to raise the number of transplantations in our material by 25%.

Calicopyelocystostomy in auto- and allotransplanted kidneys. Report of 2 cases.

A case of calicopyelocystostomy and one of pyelocystostomy are reported. In the first case, the operation was performed on an autotransplanted kidney. The operation was done in a patient with sponge kidney to facilitate spontaneous excretion of calculi. In the second case, the operation was performed in a patient with long-lasting urinary fistula which developed in a cadaver kidney transplant. Although the authors present only 2 cases, calicopyelocystostomy and pyelocystostomy can be recommended as a valuable method in complicated cases of recurrent nephrolithiasis and in patients with nonhealing long-lasting urinary fistulas which developed in transplanted kidneys.