Effective field theory for Sp(N) antiferromagnets and its phase structure

In this paper, we study quantum Sp(N) antiferromagnetic (AF) Heisenberg models in two dimensions (2D) by using the Schwinger-boson representation and the path-integral methods. An effective field theory, which is an extension of CP^{N-1} model in (2+1)D, is derived and its phase structure is studied by the 1/N-expansion. We introduce a spatial anisotropy in the exchange couplings and show that the effective coupling constant in the CP^{N-1} model is an increasing function of the anisotropy. For the SU(N) AF Heisenberg model, which is a specific case of the Sp(N) model, we found that phase transition from the ordered "N\'eel state" to paramagnetic phase takes place as the anisotropy is increased. In the vicinity of the SU(N) symmetric point, this phase structure is retained. However as a parameter that controls explicit breaking of the SU(N) symmetry is increased, a new phase, which is similar to the spiral-spin phase with a nematic order in frustrated SU(2) spin systems, appears. It is shown that at that phase transition point, a local SU(2) gauge symmetry with composite SU(2) gauge field appears in the low-energy sector. It is another example of symmetry-enhancement phenomenon at low energies. We also introduce a lattice gauge-theoretical model, which is a counterpart of the effective field theory, and study its phase structure by means of the Monte-Carlo simulations.Comment: 30 pages, 15 figure

The Effects of Restricting Nitrogen, Phosphorus, and Potassium Fertilizers on Erianthus (\u3cem\u3eErianthus arundinaceus\u3c/em\u3e) Growth and Nutrient Contents

Low inputs and sustainability are the major concerns in bioenergy crop production (Reijnders 2006). Erianthus spp. is a relative of sugarcane and is a perennial crop with high dry matter production (Matsuo et al. 2003). It is expected to become a cellulosic bioenergy crop. However, its fertilizer requirements are still unknown because erianthus has a highly developed root system (Matsuo et al. 2003), and appears to absorb nutrients from the subsoil layer, which is hardly used by other crops. Therefore, it is necessary to experimentally restrict fertilizer application and maintain the rhizosphere to clarify the fertilizer requirements. In this study, we grew Erianthus (Erianthus arundinaceus) in pots and restricted nitrogen (N), phosphorus (P), and potassium (K) fertilizer application to evaluate the fertilizer requirements

Evolution in an oncogenic bacterial species with extreme genome plasticity: Helicobacter pylori East Asian genomes

<p>Abstract</p> <p>Background</p> <p>The genome of <it>Helicobacter pylori</it>, an oncogenic bacterium in the human stomach, rapidly evolves and shows wide geographical divergence. The high incidence of stomach cancer in East Asia might be related to bacterial genotype. We used newly developed comparative methods to follow the evolution of East Asian <it>H. pylori </it>genomes using 20 complete genome sequences from Japanese, Korean, Amerind, European, and West African strains.</p> <p>Results</p> <p>A phylogenetic tree of concatenated well-defined core genes supported divergence of the East Asian lineage (hspEAsia; Japanese and Korean) from the European lineage ancestor, and then from the Amerind lineage ancestor. Phylogenetic profiling revealed a large difference in the repertoire of outer membrane proteins (including <it>oipA</it>, <it>hopMN</it>, <it>babABC</it>, <it>sabAB </it>and <it>vacA-2</it>) through gene loss, gain, and mutation. All known functions associated with molybdenum, a rare element essential to nearly all organisms that catalyzes two-electron-transfer oxidation-reduction reactions, appeared to be inactivated. Two pathways linking acetyl~CoA and acetate appeared intact in some Japanese strains. Phylogenetic analysis revealed greater divergence between the East Asian (hspEAsia) and the European (hpEurope) genomes in proteins in host interaction, specifically virulence factors (<it>tipα</it>), outer membrane proteins, and lipopolysaccharide synthesis (human Lewis antigen mimicry) enzymes. Divergence was also seen in proteins in electron transfer and translation fidelity (<it>miaA, tilS</it>), a DNA recombinase/exonuclease that recognizes genome identity (<it>addA</it>), and DNA/RNA hybrid nucleases (<it>rnhAB</it>). Positively selected amino acid changes between hspEAsia and hpEurope were mapped to products of <it>cagA</it>, <it>vacA</it>, <it>homC </it>(outer membrane protein), <it>sotB </it>(sugar transport), and a translation fidelity factor (<it>miaA</it>). Large divergence was seen in genes related to antibiotics: <it>frxA </it>(metronidazole resistance), <it>def </it>(peptide deformylase, drug target), and <it>ftsA </it>(actin-like, drug target).</p> <p>Conclusions</p> <p>These results demonstrate dramatic genome evolution within a species, especially in likely host interaction genes. The East Asian strains appear to differ greatly from the European strains in electron transfer and redox reactions. These findings also suggest a model of adaptive evolution through proteome diversification and selection through modulation of translational fidelity. The results define <it>H. pylori </it>East Asian lineages and provide essential information for understanding their pathogenesis and designing drugs and therapies that target them.</p

The Pavlik harness in the treatment of developmentally dislocated hips: results of Japanese multicenter studies in 1994 and 2008

AbstractBackgroundIt has already been more than 50years since the Pavlik harness was introduced in Japan, and today the Pavlik harness is widely recognized as the standard initial treatment modality for developmental dysplasia of the hip. We performed a multicenter nationwide questionnaire study concerning the results of Pavlik harness treatment twice in 1994 and 2008.MethodsIn 1994 and in 2008, we sent questionnaires to 12 institutes in Japan specializing mainly in pediatric orthopedics. We compare the results of these two studies and discuss differences in reduction rates, incidence of avascular necrosis in the femoral epiphysis and the percentage of joints with acceptable morphology (Severin grade I+II/total) at skeletal maturity. We statistically assessed these results to see whether there were changes in the treatment outcomes over this 14-year period.ResultsReduction of the dislocated hips was obtained by the Pavlik harness in 80.2% (1990/2481 hips; 1994) and 81.9% (1248/1523 hips; 2008). The incidences of avascular necrosis of the proximal femoral epiphysis in the dysplastic hips were 14.3% (119/835 hips; 1994) and 11.5% (76/663 hips; 2008). The type of avascular necrosis in hips from the 2008 study was determined according to the classification of Kalamchi and MacEwen: 24/69 hips (34.8%) were classified as group I; 20/69 hips (29.0%) as group II; 11/69 hips (15.9%) as group Ill; 14/69 hips (20.3%) as group IV. The percentages of hips with acceptable outcomes at skeletal maturity discerned from Severin X-ray changes (grade I+II/total) were 72.3% (604/835 hips; 1994) and 77.7% (488/628 hips; 2008).ConclusionReduction rates and the incidence of avascular necrosis in 2008 were statistically similar to the results in 1994. The rate of acceptable outcome (Severin grade I+II/total) in 2008 was statistically higher than that of 1994

A deeply branching thermophilic bacterium with an ancient acetyl-CoA pathway dominates a subsurface ecosystem

<div><p>A nearly complete genome sequence of <em>Candidatus</em> ‘Acetothermum autotrophicum’, a presently uncultivated bacterium in candidate division OP1, was revealed by metagenomic analysis of a subsurface thermophilic microbial mat community. Phylogenetic analysis based on the concatenated sequences of proteins common among 367 prokaryotes suggests that <em>Ca.</em> ‘A. autotrophicum’ is one of the earliest diverging bacterial lineages. It possesses a folate-dependent Wood-Ljungdahl (acetyl-CoA) pathway of CO₂ fixation, is predicted to have an acetogenic lifestyle, and possesses the newly discovered archaeal-autotrophic type of bifunctional fructose 1,6-bisphosphate aldolase/phosphatase. A phylogenetic analysis of the core gene cluster of the acethyl-CoA pathway, shared by acetogens, methanogens, some sulfur- and iron-reducers and dechlorinators, supports the hypothesis that the core gene cluster of <em>Ca.</em> ‘A. autotrophicum’ is a particularly ancient bacterial pathway. The habitat, physiology and phylogenetic position of <em>Ca.</em> ‘A. autotrophicum’ support the view that the first bacterial and archaeal lineages were H₂-dependent acetogens and methanogenes living in hydrothermal environments.</p> </div