1,010 research outputs found
Four-fermion decay of Higgs bosons
We calculate four-fermion decays of a Higgs boson via and/or
intermediate states for Higgs masses below . We examine models with a
doubly-charged Higgs boson and show that the four-fermion decay is the
dominant mode for a wide range of parameter space. Existing searches for
in decays have not looked for this mode. We also derive
four-fermion decay rate for a neutral Higgs boson.Comment: 12 pages, 4 figures, uses an obsolete version of phyzzx with
modification (included in the file). Missing preprint no. adde
Cosmological stretching of perturbations on a cosmic string
We investigate the effects of cosmological expansion on the spectrum of
small-scale structure on a cosmic string. We simulate the evolution of a string
with two modes that differ in wavelength by one order of magnitude. Once the
short mode is inside the horizon, we find that its physical amplitude remains
unchanged, in spite of the fact that its comoving wavelength decreases as the
longer mode enters the horizon. Thus the ratio of amplitude to wavelength for
the short mode becomes larger than it would be in the absence of the long mode.Comment: 11 pages, 5 postscript figure
3,6-Diphenyltetrazine as Cathode Active Material for Sodium Ion Batteries
3, 6-diphenyltetrazine (DPT) is an electron-deficient π-conjugated molecule with a perfectly planar structure and high crystallinity. In this study, discharge-charge tests of crystalline DPT as a cathode material for sodium ion batteries were conducted. DPT showed an initial reversible capacity of 102 mAh/g (theoretical capacity 114 mAh/g), corresponding to one electron reaction. The plateau of the discharge-charge profiles was observed at 1.9–2.1 V vs. Na/Na⁺. According to the ex-situ XRD, FT-IR, and XPS measurements to investigate the discharge-charge mechanism, the redox center was identified as the conjugated tetrazine ring. DPT was in a crystalline form in both the charged and discharged state and indicated the potential as a reversible Na ion host
Biomass and Productivity of Thalassia testudinum in Estuaries of the Florida Panhandle
Thalassia testudinum often dominates seagrass meadows of the Florida panhandle but few measurements of productivity, biomass, density, turnover or leaf area index in this region have been made. We targeted 5 estuaries located at similar latitudes, 30⁰ ± 0.3⁰N: Big Lagoon, Santa Rosa Sound, St. Andrew Bay, St. Joseph Bay, and St. George Sound. This study was one component of a collaborative partnership of state and local researchers examining factors preventing recovery in panhandle estuarine areas that had historically contained seagrass in the 1940s and 1950s. Measurements were made twice in 2016, once in June and then again in summer or fall, except in Santa Rosa Sound where measurements were made 3 times. In the estuaries sampled for the second time in July or August, aboveground productivity was greater than in June. St. Joseph Bay had the highest aboveground productivity (4.3 g/m2/d) and 1—sided leaf area index (4.2) while St. George Sound had the lowest values (0.41 g/m2/d and 1.0). Principal component analysis suggested that St. Andrew Bay, Big Lagoon and Santa Rosa Sound were the most similar, with higher values for shoot densities and leaf turnover and lower salinities and watershed:water ratios. St. Joseph Bay had high aboveground productivity and salinity, and low turbidity. St. George Sound had low aboveground productivity, high total suspended solids and the highest watershed:water ratio. These baseline productivity estimates will be useful to assess the success of restoration efforts targeting seagrasses in the Florida panhandle and evaluate impacts of climate change on seagrasses
Cosmic String Cusps with Small-Scale Structure: Their Forms and Gravitational Waveforms
We present a method for the introduction of small-scale structure into
strings constructed from products of rotation matrices. We use this method to
illustrate a range of possibilities for the shape of cusps that depends on the
properties of the small-scale structure. We further argue that the presence of
structure at cusps under most circumstances leads to the formation of loops at
the size of the smallest scales. On the other hand we show that the
gravitational waveform of a cusp remains generally unchanged; the primary
effect of small-scale structure is to smooth out the sharp waveform emitted in
the direction of cusp motion.Comment: RevTeX, 8 pages. Replaced with version accepted for publication by
PR
Observations On the Potential Confinement of a Light Fermion
We consider possible dynamical models for a light fermion confined by a
potential field. With the Dirac equation only Lorentz scalar confinement yields
normalizable wavefunctions, while with the ``no pair'' variant of the Dirac
equation only Lorentz vector confinement has normal Regge behaviour.
A systematic investigation of Regge properties and phenomenological
properties is carried out, including calculations of the Isgur-Wise function.
We point out that the Isgur-Wise function provides a sensitive test of
confinement models. In particular, the slope of the IW function at zero recoil
point is found to be for the Dirac equation with scalar
confinement, and for the no pair equation with vector
confinement. Using heavy-light data alone we argue against scalar confinement.Comment: Latex (uses epsf macro), 25 pages of text, 12 postscript figures
included. One reference is added and some typos are fixe
Kinetoplastids:related protozoan pathogens, different diseases
Kinetoplastids are a group of flagellated protozoans that include the species Trypanosoma and Leishmania, which are human pathogens with devastating health and economic effects. The sequencing of the genomes of some of these species has highlighted their genetic relatedness and underlined differences in the diseases that they cause. As we discuss in this Review, steady progress using a combination of molecular, genetic, immunologic, and clinical approaches has substantially increased understanding of these pathogens and important aspects of the diseases that they cause. Consequently, the paths for developing additional measures to control these “neglected diseases” are becoming increasingly clear, and we believe that the opportunities for developing the drugs, diagnostics, vaccines, and other tools necessary to expand the armamentarium to combat these diseases have never been better
A fluorescent microporous crystalline dendrimer discriminates vapour molecules
A self-assembled crystalline microporous dendrimer framework (MDF) exhibits novel turn-on and ratiometric fluorescence upon exposure to solvent vapours. The donor–acceptor character, combined with the large surface area (>650 m2 g−1), allows the MDF to discriminate vapours of volatile solvents with turn-on and colour change of photoluminescence
Parent-of-origin-specific allelic associations among 106 genomic loci for age at menarche.
Age at menarche is a marker of timing of puberty in females. It varies widely between individuals, is a heritable trait and is associated with risks for obesity, type 2 diabetes, cardiovascular disease, breast cancer and all-cause mortality. Studies of rare human disorders of puberty and animal models point to a complex hypothalamic-pituitary-hormonal regulation, but the mechanisms that determine pubertal timing and underlie its links to disease risk remain unclear. Here, using genome-wide and custom-genotyping arrays in up to 182,416 women of European descent from 57 studies, we found robust evidence (P < 5 × 10(-8)) for 123 signals at 106 genomic loci associated with age at menarche. Many loci were associated with other pubertal traits in both sexes, and there was substantial overlap with genes implicated in body mass index and various diseases, including rare disorders of puberty. Menarche signals were enriched in imprinted regions, with three loci (DLK1-WDR25, MKRN3-MAGEL2 and KCNK9) demonstrating parent-of-origin-specific associations concordant with known parental expression patterns. Pathway analyses implicated nuclear hormone receptors, particularly retinoic acid and γ-aminobutyric acid-B2 receptor signalling, among novel mechanisms that regulate pubertal timing in humans. Our findings suggest a genetic architecture involving at least hundreds of common variants in the coordinated timing of the pubertal transition
Agrobacterium rhizogenes-Mediated Transformation of the Parasitic Plant Phtheirospermum japonicum
Background: Plants within the Orobanchaceae are an agriculturally important group of parasites that attack economically important crops to obtain water and nutrients from their hosts. Despite their agricultural importance, molecular mechanisms of the parasitism are poorly understood. Methodology/Principal Findings: We developed transient and stable transformation systems for Phtheirospermum japonicum, a facultative parasitic plant in the Orobanchaceae. The transformation protocol was established by a combination of sonication and acetosyringone treatments using the hairy-root-inducing bacterium, Agrobacterium rhizogenes and young seedlings. Transgenic hairy roots of P. japonicum were obtained from cotyledons 2 to 3 weeks after A. rhizogenes inoculation. The presence and the expression of transgenes in P. japonicum were verified by genomic PCR, Southern blot and RT-PCR methods. Transgenic roots derived from A. rhizogenes-mediated transformation were able to develop haustoria on rice and maize roots. Transgenic roots also formed apparently competent haustoria in response to 2,6dimethoxy-1,4-benzoquinone (DMBQ), a haustorium-inducing chemical. Using this system, we introduced a reporter gene with a Cyclin B1 promoter into P. japonicum, and visualized cell division during haustorium formation. Conclusions: We provide an easy and efficient method for hairy-root transformation of P. japonicum. Transgenic marker analysis revealed that cell divisions during haustorium development occur 24 h after DMBQ treatment. The protocol
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