Ground state factorization of heterogeneous spin models in magnetic fields

The exact factorized ground state of a heterogeneous (ferrimagnetic) spin model which is composed of two spins ($\rho, \sigma$) has been presented in detail. The Hamiltonian is not necessarily translational invariant and the exchange couplings can be competing antiferromagnetic and ferromagnetic arbitrarily between different sub-lattices to build many practical models such as dimerized and tetramerized materials and ladder compounds. The condition to get a factorized ground state is investigated for non-frustrated spin models in the presence of a uniform and a staggered magnetic field. According to the lattice model structure we have categorized the spin models in two different classes and obtained their factorization conditions. The first class contains models in which their lattice structures do not provide a single uniform magnetic field to suppress the quantum correlations. Some of these models may have a factorized ground state in the presence of a uniform and a staggered magnetic field. However, in the second class there are several spin models in which their ground state could be factorized whether a staggered field is applied to the system or not. For the latter case, in the absence of a staggered field the factorizing uniform field is unique. However, the degrees of freedom for obtaining the factorization conditions are increased by adding a staggered magnetic field.Comment: 16 pages, 6 figures, 1 table, Accepted in Progress of Theoretical Physic

Factorized ground state for a general class of ferrimagnets

We have found the exact (factorized) ground state of a general class of ferrimagnets in the presence of a magnetic field which covers the frustrated, anisotropic and long range interactions for arbitrary dimensional space. In particular cases, our model represents the bond-alternating, ferromagnet-antiferromagnet and also homogeneous spin $s$ model. The factorized ground state is a product of single particle kets on a bipartite lattice composed of two different spins ($\rho, \sigma$). The spin waves analysis around the exact ground state show two branch of excitations which is the origin of two dynamics of the model. The signature of these dynamics is addressed as a peak and a broaden bump in the specific heat.Comment: 4 pages and 2 figures, some typos correcte

Cytoplasmic Effect on Groat Protein Content in lnterspecific Matings of Avena sativa L. and A. sterilis L.

Thirty sets of reciprocal isopopulations, each with 20 Fi-derived oat lines from the BC0, BC1, and BC2 of all possible matings among five Awia slerilis L. accessions and two A. saliva cultivars, were evaluated in a replicated field trial to determine whether groat protein content was influenced by cytoplasmic inheritance and to study associations between protein content and agronomic traits. A. slerili cytoplasm had no direct effect on groat protein content, but significant interactions between the cytoplasms and nuclear genes from A. saliva and A. s1erilis were detected. Thus, the potential may exist for improving groat protein content of cultivated oats by exploiting specific intra and interspecific nucleo-cytoplasmic combinations. Generally, associations of various traits with groat protein content showed no trend for change over successive backcrosses, but phenotypic and genotypic correlations between protein percentage and all traits except harvest index tended to be larger for lines with A. s1erilis cytoplasm than those with A. saliva cytoplasm

An integrated approach to climate change, income distribution, employment, and economic growth

A demand-driven growth model involving capital accumulation and the dynamics of greenhouse gas (GHG) concentration is set up to examine macroeconomic issues raised by global warming, e.g. effects on output and employment of rising levels of GHG; offsets by mitigation; relationships among energy use and labor productivity, income distribution, and growth; the economic significance of the Jevons and other paradoxes; sustainable consumption and possible reductions in employment; and sources of instability and cyclicality implicit in the two-dimensional dynamical sysem. The emphasis is on the combination of biophysical limits and Post-Keynesian growth theory and the qualitative patterns of system adjustment and the dynamics that emerge

A survey on age, growth and reproduction of Capoeta capoeta gracilis of the Madarsoo River, Golestan National Park, north-east Iran

In the years 2001 and 2002, two great floods occurred in the Madarsoo River in Golestan National Park, north-east of Iran. To study the effects of these floods, we assessed the age, growth and reproduction of Capoeta capoeta gracilis (Keyserlhng, 1861) in the river from November 2003 to December 2004. Fishes were caught by electroshocker and 1025 specimens were randomly selected from the catch. Growth in length was expressed for both sexes with Von Bertalanffy equation. Growth parameters were estimated as L infinity =249mm, K=0.22 per year and t _ (0) = -0.30 year for males and L infinity =306mm, K=0.21 per year and t _ (0) = -0.38 year for females. The length-weight relationships were described for males as lnW= -4.48 + 3.03 lnTL and as lnW= -4.59+3.0551 lnTL for females which shows a good feeding condition and a positive-isometric growth. Difference of length distribution between males and females is significant and males have lower lengths because this sex matures sooner so its growth is lower than females. Difference of fish length distribution between this study and previous studies on the C. capoeta gracilis of the river is significant and Lenkoran's length shows great decrease in this study as compared to previous studies. Age of the fishes ranged from 1 ^+ to 5 ^+ for males and 2 ^+ to 8 ^+ for females, the dominant age was 2 ^+ and the mean age was calculated as 2.009 ±0.034. We found that C. capoeta gracilis population had become younger in this study, so we concluded that the floods had made great changes in age and length structure of the fish

Phase diagram of the XXZ ferrimagnetic spin-(1/2, 1) chain in the presence of transverse magnetic field

We investigate the phase diagram of an anisotropic ferrimagnet spin-(1/2, 1) in the presence of a non-commuting (transverse) magnetic field. We find a magnetization plateau for the isotropic case while there is no plateau for the anisotropic ferrimagnet. The magnetization plateau can appear only when the Hamiltonian has the U(1) symmetry in the presence of the magnetic field. The anisotropic model is driven by the magnetic field from the N\'{e}el phase for low fields to the spin-flop phase for intermediate fields and then to the paramagnetic phase for high fields. We find the quantum critical points and their dependence on the anisotropy of the aforementioned field-induced quantum phase transitions. The spin-flop phase corresponds to the spontaneous breaking of Z2 symmetry. We use the numerical density matrix renormalization group and analytic spin wave theory to find the phase diagram of the model. The energy gap, sublattice magnetization, and total magnetization parallel and perpendicular to the magnetic field are also calculated. The elementary excitation spectrums of the model are obtained via the spin wave theory in the three different regimes depending on the strength of the magnetic field.Comment: 14 pages, 11 eps figure

Distribution, diversity and abundance of fish species in the Madarsoo River, Golestan National Park, Iran

To assess the effects of two flooding events occurred in the years 2001 and 2002, fish distribution, diversity and abundance in Madarsoo River of the Golestan National Park were studied and compared to that of the years before the events. A total of five fish species from four sites were collected. Assemblage of fish population showed changes in their overall relative abundance and distribution across sampling sites and times. We estimated the abundance of Capoeta capoeta gracilis at 2.331:2.6, Alburnoides bipunctatus at 0.17±0.15, Paracobitis malapterura at 0.0474±0.031 and Leuciscus cephalus at 0.005±0.01 fish per square meter of the stream. The abundance of Cc.gracilis showed significant increase while that of the A. bipunctatus did not undergo such significant change in comparison with the data from the years before flooding events (P<0.01). The Shannon diversity index was significantly different between sites and with the increase in the number of riffles and pools in the river, the index and population size of the fish species showed an upward trend. Three fish species Oncorhynchus mykiss, Neogobius melanostomus affinis and Neogobius fluviafilis which were abundant before the floods did not show up in the samples at all. Also, of the Barbus mursa, only one specimen was caught. Canonical correspondence analysis (CCA) results suggest that two species C. c. gracilis and P. malapterura are more resistant against changes in environmental conditions

P 419 Comparison of tight junctions permeability and modulation in iris pigment epithelium and retinal pigment epithelium in vitro

Amb una superfície: 0,61 ha, de basalt i aigua nebulitzada.Barragán, Pedro (dissenyador)Gran pla general de El Volcà,conegut com la Carbonera. El carbó calent era mullat per aigua subterrània i desprenia vapor. Actualment està inactiu. Destaquen el pg. Josep Carner amb el monument a Colom i els edificis de Capitania i Duana

Implicit carbon prices: Making do with the taxes we have

Climate and fiscal policy interact closely. The former imposes explicit prices for carbon emissions, while the latter affects emissions implicitly. We study the correspondence between explicit and implicit carbon pricing of a Ramsey-optimal fiscal policy in a neoclassical growth model of climate change. Our central result is that any arbitrary sequence of explicit carbon prices can be achieved implicitly through a blend of conventional taxes (e.g., consumption, energy, and income taxes), when lump-sum transfers are available. In a Ramsey setting, policy balances these taxes’ traditional revenue-raising role with the Pigouvian role of fixing the climate externality. We characterize the Ramsey and Pigouvian components of optimal tax rates. We show that explicit carbon pricing is implicitly implementable through a mix of conventional taxes also in this framework. We extend these findings to scenarios compatible with net-zero emissions, adding carbon capture technologies and a cap on cumulative emissions