The proton and neutron distribution in Na isotopes: the development of halo and shell structure

The interaction cross sections for $^A Na + ^{12}C$ reaction are calculated using Glauber model. The continuum Hartree-Bogoliubov theory has been generalized to treat the odd particle system and take the continuum into account. The theory reproduces the experimental result quite well. The matter distributions from the proton drip line to the neutron drip line in Na isotopes have been systematically studied and presented. The relation between the shell effects and the halos has been examined. The tail of the matter distribution shows a strong dependence on the shell structure. The neutron N=28 closure shell fails to appear due to the coming down of the $2p_{3/2}$ and $2p_{1/2}$. The development of the halo was understood as changes in the occupation in the next shell or the sub-shell close to the continuum limit. The central proton density is found to be decreasing near the neutron drip line, which is due to the proton-neutron interaction. However the diffuseness of the proton density does not change for the whole Na isotopes.Comment: 10 pages, 4 figure

The Effect of Nuclear Rotation on the Collective Transport Coefficients

We have examined the influence of rotation on the potential energy and the transport coefficients of the collective motion (friction and mass coefficients). For axially symmetric deformation of nucleus Th-224 we have found that at excitations corresponding to temperatures T > 1 MeV the shell correction to the liquid drop energy practically does not depend on the angular rotation. The friction and mass coefficients obtained within the linear response theory for the same nucleus at temperatures larger than T=2 MeV are rather stable with respect to rotation provided that the contributions from spurious states arising due to the violation of rotation symmetry are removed. At smaller excitations both friction and mass parameters corresponding to the elongation mode are growing functions of rotational frequency.Comment: 16 pages, 5 eps figures, Latex, submitted to Nucl.Phys.

Ground state of the three-band Hubbard model

The ground state of the two-dimensional three-band Hubbard model in oxide superconductors is investigated by using the variational Monte Carlo method. The Gutzwiller-projected BCS and spin- density wave (SDW) functions are employed in the search for a possible ground state with respect to dependences on electron density. Antiferromagnetic correlations are considerably enhanced near half-filling. It is shown that the d-wave state may exist away from half-filling for both the hole and electron doping cases. The overall structure of the phase diagram obtained by the calculations qualitatively agrees with experimental indications. The superconducting condensation energy is in reasonable agreement with the experimental value obtained from specific heat and critical magnetic field measurements for optimally doped samples. The inhomogeneous SDW state is also examined near 1/8-hole doping.Comment: 10 pages, 17 figure

Molecular mechanisms and regulation of iron transport

Iron is an essential micronutrient for almost all the organisms, yet toxic in excess. Because there is no physiological mechanism to excrete iron, absorption is tightly regulated. In mammals, absorption takes place mainly in upper part of duodenum, and exact mechanisms are still unclear. In the past 5 years, a number of proteins involved in iron absorption has been identified and characterised. Divalent metal transporter 1 (DMT1, also known as Nramp2, DCT1, and SLC11A2) is the only known importer of inorganic iron into the body, and iron regulated transporter 1 (IREG1, also known as ferroportin, and MTP1) has been characterised as the iron exporter out of the enterocytes. The regulatory mechanisms of iron absorption are still unknown, though it is influenced by dietary iron, body iron store, and erythropoiesis. The level of other metals, such as zinc and copper, is also known to influence iron absorption. In thesis Caco-2 TC7 cells were used as a model of human intestine to investigating the possible regulatory mechanism of iron uptake by dietary metals (iron, copper, and zinc), and humoral signal from body store. Cells were cultured in plates for 21 days. For the final 24 h of the culture period, metals (iron, copper, and zinc) or human synthetic hepcidin (humoral signal) was added to the basolateral medium. At the end of the incubation period cells were used for analysis of changes in transporter gene expression. Caco-2 cells were also cultured in transwell, and used to measure 55Fe transport across the cell monolayers. Following exposure to iron, apical transporter, DMT1, was down regulated, whereas basolateral iron transporter IREG1 expression was unaffected. Interestingly gene expression of Hephaestin, which co-work with IREG1 at basolateral surface of the cell, was also down regulated. Copper, and zinc also down regulated DMT1 and hephaestin expression, as well as apical zinc transporter Zip1 in Caco-2 TC7 cells. Interestingly, exposure to copper and zinc significantly up regulated the expression of IREG1. Iron uptake across the apical membrane of Caco-2 cells was significantly decreased by exposure to hepcidin, whereas efflux across the basolateral membrane was unaffected by hepcidin treatment. In agreement with the transport data, the gene expression of DMT1 was decreased by hepcidin treatment and expression of IREG1 was unaffected. Additionally, the effect of iron (hemin) in macrophages was also investigated and found that their responses do not correspond to intestine

Low-temperature specific heat for ferromagnetic and antiferromagnetic orders in CaRu1-xMnxO3

Low-temperature specific heat of CaRu1-xMnxO3 was measured to clarify the role of d electrons in ferromagnetic and antiferromagnetic orders observed above x=0.2. Specific heat divided by temperature C_p/T is found to roughly follow a T^2 function, and relatively large magnitudes of electronic specific heat coefficient gamma were obtained in wide x range. In particular, gamma is unchanged from the value at x=0 (84 mJ/K^2 mol) in the paramagnetic state for x<=0.1, but linearly reduced with increasing x above x= 0.2. These features of gamma strongly suggest that itinerant d electrons are tightly coupled with the evolution of magnetic orders in small and intermediate Mn concentrations.Comment: 4 pages, 2 figures, to be published in J. Phys.: Conf. Ser. (SCES 2011, Cambridge, UK

Search for Photon-Photon Elastic Scattering in the X-ray Region

We report the first results of a search for real photon-photon scattering using X rays. A novel system is developed to split and collide X-ray pulses by applying interferometric techniques. A total of $6.5\times10^{5}$ pulses (each containing about $10^{11}$ photons) from an X-ray Free-Electron Laser are injected into the system. No scattered events are observed, and an upper limit of $1.7\times 10^{-24}$ ${\rm m^{2}}$ (95% C.L.) is obtained on the photon-photon elastic scattering cross section at 6.5 keV

Sign reversals of the Quantum Hall Effect in quasi-1D conductors

The sign reversals of the Quantum Hall Effect observed in quasi-one-dimensional conductors of the Bechgaard salts family are explained within the framework of the quantized nesting model. The sequence of reversals is driven by slight modifications of the geometry of the Fermi surface. It is explained why only even phases can have signign reversals and why negative phases are less stable than positive ones.Comment: 4 LaTex pages, 3 Postscript figure