spl(2,1) dynamical supersymmetry and suppression of ferromagnetism in flat band double-exchange models

The low energy spectrum of the ferromagnetic Kondo lattice model on a N-site complete graph extended with on-site repulsion is obtained from the underlying spl(2,1) algebra properties in the strong coupling limit. The ferromagnetic ground state is realized for 1 and N+1 electrons only. We identify the large density of states to be responsible for the suppression of the ferromagnetic state and argue that a similar situation is encountered in the Kagome, pyrochlore, and other lattices with flat bands in their one-particle density of states.Comment: 7 pages, 1 figur

Systematics of local pion optical model parameters

A simple six-parameter local optical potential has been used to fit the global supply of pion-nucleus elastic scattering data, with good success. The resulting real and imaginary well-depths show a striking resonant structure, derived from the underlying pion-nucleon resonances

Forecasting demand: development of a fuzzy growth adjusted holt-winters approach

Irrespective of the type of items manufactured by an industry, environment is now becoming progressively more and more competitive than the past few decades. To sustain in this severe competition, companies have no choice but to manage their operations optimally and in this respect the importance of more accurate demand prediction cannot be exaggerated. This research presents a forecasting approach tailoring the multiplicative Holt-Winters method with growth adjustment through incorporation of fuzzy logic. The growth parameter of the time series values is adjusted with the conventional Holt-Winters method and tested for predicting the real-life demand of transformer tank experienced by a local company. The result obtained by applying the new approach shows a significant improvement in the accuracy of the forecasted demand and sheds light on further enhancement of the proposed method by optimizing other time series parameters through fuzzy logic application for possible application in prediction of demand having trend, seasonal and cyclical changes

Low Temperature Magnetic Properties of the Double Exchange Model

We study the {\it ferromagnetic} (FM) Kondo lattice model in the strong coupling limit (double exchange (DE) model). The DE mechanism proposed by Zener to explain ferromagnetism has unexpected properties when there is more than one itinerant electron. We find that, in general, the many-body ground state of the DE model is {\it not} globally FM ordered (except for special filled-shell cases). Also, the low energy excitations of this model are distinct from spin wave excitations in usual Heisenberg ferromagnets, which will result in unusual dynamic magnetic properties.Comment: 5 pages, RevTeX, 5 Postscript figures include

Antiferromagnetic Heisenberg model on anisotropic triangular lattice in the presence of magnetic field

We use Schwinger boson mean field theory to study the antiferromagnetic spin-1/2 Heisenberg model on an anisotropic triangular lattice in the presence of a uniform external magnetic field. We calculate the field dependence of the spin incommensurability in the ordered spin spiral phase, and compare the results to the recent experiments in Cs$_{2}$CuCl$_{4}$ by Coldea et al. (Phys. Rev. Lett. 86, 1335 (2001)).Comment: 4 pages with 4 figures include

Temperature dependence of the resistivity in the double-exchange model

The resistivity around the ferromagnetic transition temperature in the double exchange model is studied by the Schwinger boson approach. The spatial spin correlation responsible for scattering of conduction electrons are taken into account by adopting the memory function formalism. Although the correlation shows a peak lower than the transition temperature, the resistivity in the ferromagnetic state monotonically increases with increasing temperature due to a variation of the electronic state of the conduction electron. In the paramagnetic state, the resistivity is dominated by the short range correlation of scattering and is almost independent of the temperature. It is attributed to a cancellation between the nearest-neighbor spin correlation, the fermion bandwidth, and the fermion kinetic energy. This result implies the importance of the temperature dependence of the electronic states of the conduction electron as well as the localized spin states in both ferromagnetic and paramagnetic phases.Comment: RevTex, 4 pages, 4 PostScript figures, To appear in Phys. Rev.

Modulation of Macrophage Function by Lactobacillus-Conditioned Medium

open access articleProbiotics are used as microbial food supplements for health and well-being. They are thought to have immunomodulatory effects although their exact physiological mechanism of action is not clear. This study investigated the influence of probiotic Lactobacillus rhamnosus GG conditioned media (LGG-CM) on macrophage phagocytosis of non-pathogenic Escherichia coli HfrC. The gentamicin protection assay was used to study the bacterial killing phases of phagocytosis. Macrophages co-incubated with E. coli for an hour allowed them to ingest bacteria and then the rate of E. coli killing was monitored for up to 300 min to determine the killing or digestion of the bacteria by recovering them from the macrophage lysate. We found that the LGG-CM significantly increased the bacterial killing by approximately 6-fold when compared with that of controls. By contrast, this killing process was found to be associated with enhanced free radical production via the activation of NADPH oxidase, stimulated by the LGG conditioned medium. We also found that the conditioned medium had small effect on nitric oxide (NO) generation, albeit to a lesser extent. This work suggests that LGG-CM may play an important role in suppressing the total microbial load within the macrophages and hence, the extent to which pro-inflammatory molecules such as free radicals and NO are generated. The modulation of inflammation-promoting signals by LGG-CM may be beneficial as it modulates bacterial killing, and thereby prevents any collateral damage to host

Annual Biomass Production, Chemical Composition and In- sacco Degradability of Different Cultivars of Moringa oleifera

Types of plant cultivars and seasons often affect production and productivity of fodder biomass and nutritional quality to animals. Selection of suitable cultivars and better understanding of year round biomass production are indispensable for improving quality feed supply to animals. Black Seed Moringa (BSM-L) and White Seed Moringa (WSM), the two local cultivars and Black Seed Moringa (BSM-T) cultivar of Thailand origin of Moringa oleifera were cultivated in the fodder research field of the Bangladesh Livestock Research Institute (BLRI) during the period of 19 August 2014 to 23 December 2015. An agronomical trial was conducted to determine the biomass yield of the three cultivars in different seasons of a year under common agronomical practices. The effect of the cultivars on the daily relative growth rate (RGR), chemical composition and in-sacco dry matter (DM) degradability were also evaluated. The cultivar response to biomass production performances, chemical composition and nutritional values were analyzed in an ANOVA of a Randomized Block Design (RBD), while the differences in the rate and extent of the DM degradability in-sacco determined using three rumen cannulated bulls were analyzed in an ANOVA of 3x3 Latin Square Design. The annual biomass yield of BSM-L tops (114.5 t/ha fresh; 22.7 t/ha DM) was significantly higher than that of WSM (29.0 t/ha fresh; 5.80 t/ha DM) or BSM-T (83.5 t/ha fresh; 16.0 t/ha DM). No significant difference in chemical composition (224.9, 222.4 & 223.8 g.kg-1 DM of crude protein (CP), respectively, and 450.9, 455.3 & 435.4 g.kg-1 DM of neutral detergent fiber, respectively) or nutritional value (47.4, 46.7 & 45.3% of potential, and 62.8, 64.2 and 63.6% of effective degradability of dry matter) was found for the cultivars. BSM-L had a significantly higher survivability (97.2%), prune number per plant (3.50) and RGR (15.6 mg DM/day) than WSM (25.0%, 2.30 & 4.20 mg DM/day) or BSM-T (55.6%, 3.10 & 10.8 mg DM/day) respectively. The hot and dry, and hot and humid climate having a Heat Index (HI) range of 25o to 35o F and monthly total rainfall of 130 mm to 332 mm were suitable for cultivation of all the Moringa cultivars. It was concluded that considering biomass production and its quality in terms of chemical composition and nutritional values, Black Seed Moringa (Moringa oleifera) may be cultivated as a plant fodder crop for the production of feed for ruminant animals

Strong-Coupling Expansion for the Hubbard Model

A strong-coupling expansion for models of correlated electrons in any dimension is presented. The method is applied to the Hubbard model in $d$ dimensions and compared with numerical results in $d=1$. Third order expansion of the Green function suffices to exhibit both the Mott metal-insulator transition and a low-temperature regime where antiferromagnetic correlations are strong. It is predicted that some of the weak photoemission signals observed in one-dimensional systems such as $SrCuO_2$ should become stronger as temperature increases away from the spin-charge separated state.Comment: 4 pages, RevTex, 3 epsf figures include