154 research outputs found
Spontaneous Chiral-Symmetry Breaking in Three-Dimensional QED with a Chern--Simons Term
In three-dimensional QED with a Chern--Simons term we study the phase
structure associated with chiral-symmetry breaking in the framework of the
Schwinger--Dyson equation. We give detailed analyses on the analytical and
numerical solutions for the Schwinger--Dyson equation of the fermion
propagator, where the nonlocal gauge-fixing procedure is adopted to avoid
wave-function renormalization for the fermion. In the absence of the
Chern--Simons term, there exists a finite critical number of four-component
fermion flavors, at which a continuous (infinite-order) chiral phase transition
takes place and below which the chiral symmetry is spontaneously broken. In the
presence of the Chern--Simons term, we find that the spontaneous
chiral-symmetry-breaking transition continues to exist, but the type of phase
transition turns into a discontinuous first-order transition. A simple
stability argument is given based on the effective potential, whose stationary
point gives the solution of the Schwinger-Dyson equation.Comment: 34 pages, revtex, with 9 postscriptfigures appended (uuencoded
Strong Decays of Strange Quarkonia
In this paper we evaluate strong decay amplitudes and partial widths of
strange mesons (strangeonia and kaonia) in the 3P0 decay model. We give
numerical results for all energetically allowed open-flavor two-body decay
modes of all nsbar and ssbar strange mesons in the 1S, 2S, 3S, 1P, 2P, 1D and
1F multiplets, comprising strong decays of a total of 43 resonances into 525
two-body modes, with 891 numerically evaluated amplitudes. This set of
resonances includes all strange qqbar states with allowed strong decays
expected in the quark model up to ca. 2.2 GeV. We use standard nonrelativistic
quark model SHO wavefunctions to evaluate these amplitudes, and quote numerical
results for all amplitudes present in each decay mode. We also discuss the
status of the associated experimental candidates, and note which states and
decay modes would be especially interesting for future experimental study at
hadronic, e+e- and photoproduction facilities. These results should also be
useful in distinguishing conventional quark model mesons from exotica such as
glueballs and hybrids through their strong decays.Comment: 69 pages, 5 figures, 39 table
Catalysis of Dynamical Flavor Symmetry Breaking by a Magnetic Field in Dimensions
It is shown that in dimensions, a constant magnetic field is a strong
catalyst of dynamical flavor symmetry breaking, leading to generating a fermion
dynamical mass even at the weakest attractive interaction between fermions. The
effect is illustrated in the Nambu-Jona-Lasinio model in a magnetic field. The
low-energy effective action in this model is derived and the thermodynamic
properties of the model are established. The relevance of this effect for
planar condensed matter systems is pointed out.Comment: 11 pages, LaTeX. The final version (with minor corrections) which
appeared in Phys.Rev.Lett. 73 (1994) 349
De Novo Mutations in FOXJ1 Result in a Motile Ciliopathy with Hydrocephalus and Randomization of Left/Right Body Asymmetry
Hydrocephalus is one of the most prevalent form of developmental central nervous system (CNS) malformations. Cerebrospinal fluid (CSF) flow depends on both heartbeat and body movement. Furthermore, it has been shown that CSF flow within and across brain ventricles depends on cilia motility of the ependymal cells lining the brain ventricles, which play a crucial role to maintain patency of the narrow sites of CSF passage during brain formation in mice. Using whole-exome and whole-genome sequencing, we identified an autosomal-dominant cause of a distinct motile ciliopathy related to defective ciliogenesis of the ependymal cilia in six individuals. Heterozygous de novo mutations in FOXJ1, which encodes a well-known member of the forkhead transcription factors important for ciliogenesis of motile cilia, cause a motile ciliopathy that is characterized by hydrocephalus internus, chronic destructive airway disease, and randomization of left/right body asymmetry. Mutant respiratory epithelial cells are unable to generate a fluid flow and exhibit a reduced number of cilia per cell, as documented by high-speed video microscopy (HVMA), transmission electron microscopy (TEM), and immunofluorescence analysis (IF). TEM and IF demonstrate mislocalized basal bodies. In line with this finding, the focal adhesion protein PTK2 displays aberrant localization in the cytoplasm of the mutant respiratory epithelial cells
Human Resource Flexibility as a Mediating Variable Between High Performance Work Systems and Performance
Much of the human resource management literature has demonstrated the impact of high performance
work systems (HPWS) on organizational performance. A new generation of studies is
emerging in this literature that recommends the inclusion of mediating variables between HPWS
and organizational performance. The increasing rate of dynamism in competitive environments
suggests that measures of employee adaptability should be included as a mechanism that may
explain the relevance of HPWS to firm competitiveness. On a sample of 226 Spanish firms, the
study’s results confirm that HPWS influences performance through its impact on the firm’s
human resource (HR) flexibility
Use of SMS texts for facilitating access to online alcohol interventions: a feasibility study
A41 Use of SMS texts for facilitating access to online alcohol interventions: a feasibility study
In: Addiction Science & Clinical Practice 2017, 12(Suppl 1): A4
Pension reform, the stock market, capital formation and economic growth: a critical commentary on the World Bank's proposals
Abstract
Proposing far-reaching reforms to the pension systems, the World Bank has recently suggested that the existing pay-as-you-go pension systems in many rich as well as poor countries, should be replaced by fully funded, mandatory, preferably private pensions, as the main pillars of the new system. It argues that these reforms will not only benefit the pensioners, but also enhance savings, promote capital formation and economic development. This paper provides a critical examination of the Bank's theses and concludes that it has adopted a one-sided view of the relationships between the key critical variables. The proposed reform may therefore neither protect the old nor achieve faster economic growth
Pension reform, the stock market, capital formation and economic growth: A critical commentary on the World Bank's proposals
Age of acquisition, word frequency, and the role of phonology in the lexical decision task
An overview of Southern Ocean zooplankton data: abundance, biomass, feeding and functional relationships
There is an enormous amount of data on Southern Ocean (SO) zooplankton, mostly on their distribution with a minority addressing rate processes. This review aims to summarise these data and show where it resides, to assist SO food-web modellers or those with limited specialist knowledge of SO zooplankton. First, a brief overview is provided of the diversity and basic biology of SO zooplankton, with an emphasis on abundance, distribution and feeding. Second, advice is provided on the uses, strengths and limitations of zooplankton data as inputs to SO data compilations or food-web models. Copepods overall comprise >75% of the SO zooplankton biomass (excluding Euphausia superba). Total mesozooplankton biomass density differs little between the Antarctic sectors, but latitudinally it is maximal in the Polar Frontal Zone and declines to the north and south. Those compiling data on numerical density (no. m–2 or no. m–3) need to allow for differences in the extent of identification of early larval stages. Likewise, the time of year, depth of sampling and mesh size of sampler greatly influence the recorded abundance, since the populations can make seasonal vertical migrations and their pulsed reproduction causes great seasonal changes in size structure and abundance. Other issues are specific to polar environments, for example, lipid storage which leads to significantly different length-mass and mass-rate relationships than are reported in global literature compilations. Likewise, stenothermy (narrow temperature tolerance) means that fixed (Q10-type) temperature relationships based on global literature compilations must be applied with great caution in SO-specific studies. Protozoa/micrometazoa (<200 μm) are the main grazers in the SO, since mesozooplankton typically remove <30% of primary production. This emphasises the dominant role of microbial food chains involving small metazoans, relative to the classic short diatom-krill-whale type food chains. Even within regions of abundant krill, copepod production in summer roughly triples that of postlarval E. superba. This fact reflects a large flow of energy through multiple trophic levels, via copepods and their major invertebrate predators such as other predatory copepods, chaetognaths, small omnivorous euphausiids, amphipods up to myctophid fish and birds
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