583 research outputs found
Strong-coupling Analysis of Parity Phase Structure in Staggered-Wilson Fermions
We study strong-coupling lattice QCD with staggered-Wilson fermions, with
emphasis on discrete symmetries and possibility of their spontaneous breaking.
We perform hopping parameter expansion and effective potential analyses in the
strong-coupling limit. From gap equations we find nonzero pion condensate in
some range of a mass parameter, which indicates existence of the parity-broken
phase in lattice QCD with staggered-Wilson fermions. We also find massless
pions and PCAC relations around second-order phase boundary. These results
suggest that we can take a chiral limit by tuning a mass parameter in lattice
QCD with staggered-Wilson fermions as with the Wilson fermion.Comment: 37 pages, 9 figure
QCD phase diagram with 2-flavor lattice fermion formulations
We propose a new framework for investigating two-flavor lattice QCD with
finite temperature and density. We consider the Karsten-Wilczek fermion
formulation, in which a species-dependent imaginary chemical potential term can
reduce the number of species to two without losing chiral symmetry. This
lattice discretization is useful for study on finite-(,) QCD since its
discrete symmetries are appropriate for the case. To show its applicability, we
study strong-coupling lattice QCD with temperature and chemical potential. We
derive the effective potential of the scalar meson field and obtain a critical
line of the chiral phase transition, which is qualitatively consistent with the
phenomenologically expected phase diagram. We also discuss that
renormalization of imaginary chemical potential can be controlled by adjusting
a parameter of a dimension-3 counterterm.Comment: 21 pages, 11 figure
Mucinous Cystadenocarcinoma of the Colon during Pregnancy
A rare case of mucinous adenocarcinoma of the cecum in a pregnant woman is described. A 32-year-old Korean woman was diagnosed as having an abdominal tumor immediately after giving birth. Abdominal computed tomography demonstrated a smooth mass measuring 10 cm in diameter on the right side of the abdomen. Acute abdomen developed 3 days after birth. At emergency surgery, volvulus of a polypoid tumor was detected at the cecum apart from the normal appendix. We successfully performed a tumorectomy; however, histopathological examination demonstrated mucinous adenocarcinoma with a massive blood clot
Varying-coefficient modeling via regularized basis functions
We address the problem of constructing varying-coefficient models based on
basis expansions along with the technique of regularization. A crucial point in
our modeling procedure is the selection of smoothing parameters in the
regularization method. In order to choose the parameters objectively, we derive
model selection criteria from the viewpoints of information-theoretic and
Bayesian approach. We demonstrate the effectiveness of proposed modeling
strategy through Monte Carlo simulations and analyzing a real data set.Comment: 10 pages, 4 figure
Index Theorem and Overlap Formalism with Naive and Minimally Doubled Fermions
We present a theoretical foundation for the Index theorem in naive and
minimally doubled lattice fermions by studying the spectral flow of a Hermitean
version of Dirac operators. We utilize the point splitting method to implement
flavored mass terms, which play an important role in constructing proper
Hermitean operators. We show the spectral flow correctly detects the index of
the would-be zero modes which is determined by gauge field topology. Using the
flavored mass terms, we present new types of overlap fermions from the naive
fermion kernels, with a number of flavors that depends on the choice of the
mass terms. We succeed to obtain a single-flavor naive overlap fermion which
maintains hypercubic symmetry.Comment: 27 pages, 17 figures; references added, version accepted in JHE
Ecto-5’-nucleotidase: Structure function relationships
Ecto-5’-nucleotidase (ecto-5’-NT) is attached via a GPI anchor to the extracellular membrane, where it hydrolyses AMP to adenosine and phosphate. Related 5’-nucleotidases exist in bacteria, where they are exported into the periplasmic space. X-ray structures of the 5’-nucleotidase from E. coli showed that the enzyme consists of two domains. The N-terminal domain coordinates two catalytic divalent metal ions, whereas the C-terminal domain provides the substrate specificity pocket for the nucleotides. Thus, the substrate binds at the interface of the two domains. Here, the currently available structural information on ecto-5’NT is reviewed in relation to the catalytic properties and enzyme function
Mechanisms of organelle division and inheritance and their implications regarding the origin of eukaryotic cells
Mitochondria and plastids have their own DNAs and are regarded as descendants of endosymbiotic prokaryotes. Organellar DNAs are not naked in vivo but are associated with basic proteins to form DNA-protein complexes (called organelle nuclei). The concept of organelle nuclei provides a new approach to explain the origin, division, and inheritance of organelles. Organelles divide using organelle division rings (machineries) after organelle-nuclear division. Organelle division machineries are a chimera of the FtsZ (filamentous temperature sensitive Z) ring of bacterial origin and the eukaryotic mechanochemical dynamin ring. Thus, organelle division machineries contain a key to solve the origin of organelles (eukaryotes). The maternal inheritance of organelles developed during sexual reproduction and it is also probably intimately related to the origin of organelles. The aims of this review are to describe the strategies used to reveal the dynamics of organelle division machineries, and the significance of the division machineries and maternal inheritance in the origin and evolution of eukaryotes
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