Penta-quark states with hidden charm and beauty

More and more hadron states are found to be difficult to be accommodated by the quenched quark models which describe baryons as 3-quark states and mesons as antiquark-quark states. Dragging out an antiquark-quark pair from the gluon field in hadrons should be an important excitation mechanism for hadron spectroscopy. Our recent progress on the penta-quark states with hidden charm and beauty is reviewed.Comment: Plenary talk at the 5th Asia-Pacific Conference on Few-Body Problems in Physics 2011 (APFB2011), 22-26 Aug., 2011, Seoul, Kore

First fossil-leaf floras from Brunei Darussalam show dipterocarp dominance in Borneo by the Pliocene.

The Malay Archipelago is one of the most biodiverse regions on Earth, but it suffers high extinction risks due to severe anthropogenic pressures. Paleobotanical knowledge provides baselines for the conservation of living analogs and improved understanding of vegetation, biogeography, and paleoenvironments through time. The Malesian bioregion is well studied palynologically, but there have been very few investigations of Cenozoic paleobotany (plant macrofossils) in a century or more. We report the first paleobotanical survey of Brunei Darussalam, a sultanate on the north coast of Borneo that still preserves the majority of its extraordinarily diverse, old-growth tropical rainforests. We discovered abundant compression floras dominated by angiosperm leaves at two sites of probable Pliocene age: Berakas Beach, in the Liang Formation, and Kampong Lugu, in an undescribed stratigraphic unit. Both sites also yielded rich palynofloral assemblages from the macrofossil-bearing beds, indicating lowland fern-dominated swamp (Berakas Beach) and mangrove swamp (Kampong Lugu) depositional environments. Fern spores from at least nine families dominate both palynological assemblages, along with abundant fungal and freshwater algal remains, rare marine microplankton, at least four mangrove genera, and a diverse rainforest tree and liana contribution (at least 19 families) with scarce pollen of Dipterocarpaceae, today's dominant regional life form. Compressed leaves and rare reproductive material represent influx to the depocenters from the adjacent coastal rainforests. Although only about 40% of specimens preserve informative details, we can distinguish 23 leaf and two reproductive morphotypes among the two sites. Dipterocarps are by far the most abundant group in both compression assemblages, providing rare, localized evidence for dipterocarp-dominated lowland rainforests in the Malay Archipelago before the Pleistocene. The dipterocarp fossils include winged Shorea fruits, at least two species of plicate Dipterocarpus leaves, and very common Dryobalanops leaves. We attribute additional leaf taxa to Rhamnaceae (Ziziphus), Melastomataceae, and Araceae (Rhaphidophora), all rare or new fossil records for the region. The dipterocarp leaf dominance contrasts sharply with the family's <1% representation in the palynofloras from the same strata. This result directly demonstrates that dipterocarp pollen is prone to strong taphonomic filtering and underscores the importance of macrofossils for quantifying the timing of the dipterocarps' rise to dominance in the region. Our work shows that complex coastal rainforests dominated by dipterocarps, adjacent to swamps and mangroves and otherwise similar to modern ecosystems, have existed in Borneo for at least 4-5 million years. Our findings add historical impetus for the conservation of these gravely imperiled and extremely biodiverse ecosystems

Rates for the reactions antiproton-proton --> pi phi and gamma phi

We study antiproton-proton annihilation at rest into $\pi\phi$ and $\gamma\phi$. Rescattering by $\overline{K^*}K+K^*\overline{K}$ and $\rho^{+}\rho^{-}$ for $\overline{p}p\rightarrow\pi\phi$ states is sizable, of order $(0.90\, {\rm to}\,2.6)\times 10^{-4}$ in the branching ratio, but smaller than experiment. For $\overline{p}p\rightarrow\gamma\phi$ the rescattering contributions are negligible, but the $\gamma\phi$ channel is well explained by a $\rho\phi$ intermediate state combined with vector meson dominance.Comment: 12 pages, plain latex, 2 postscript figures available upon request, PSI-PR-93-2

Inhomogeneous magnetism in La-doped CaMnO3. (I) Nanometric-scale spin clusters and long-range spin canting

Neutron measurements on Ca{1-x}La{x}MnO3 (0.00 <= x <= 0.20) reveal the development of a liquid-like spatial distribution of magnetic droplets of average size ~10 Angstroms, the concentration of which is proportional to x (one cluster per ~60 doped electrons). In addition, a long-range ordered ferromagnetic component is observed for ~0.05 < x < ~0.14. This component is perpendicularly coupled to the simple G-type antiferromagnetic (G-AFM) structure of the undoped compound, which is a signature of a G-AFM + FM spin-canted state. The possible relationship between cluster formation and the stabilization of a long-range spin-canting for intermediate doping is discussed.Comment: Submitted to Physical Review

A prospective population-based study of gestational vitamin D status and brain morphology in preadolescents

Low vitamin D level during pregnancy has been associated with adverse neurodevelopmental outcomes such as autism spectrum disorders (ASD) in children. However, the underlying neurobiological mechanism remains largely unknown. This study investigated the association between gestational 25-hydroxyvitamin D [25(OH)D] concentration and brain morphology in 2597 children at the age of 10 years in the population-based Generation R Study. We studied both 25(OH)D in maternal venous blood in mid-gestation and in umbilical cord blood at delivery, in relation to brain volumetric measures and surface-based cortical metrics including cortical thickness, surface area, and gyrification using linear regression. We found exposure to higher maternal 25(OH)D concentrations in mid-gestation was associated with a larger cerebellar volume in children (b ​= ​0.02, 95%CI 0.001 to 0.04), however this association did not remain after co

Generation of arbitrary two dimensional motional state of a trapped ion

We present a scheme to generate an arbitrary two-dimensional quantum state of motion of a trapped ion. This proposal is based on a sequence of laser pulses, which are tuned appropriately to control transitions on the sidebands of two modes of vibration. Not more than $(M+1)(N+1)$ laser pulses are needed to generate a pure state with upper phonon number $M$ and $N$ in the $x$ and $y$ direction respectively.Comment: to appear in PR

Localization by disorder in the infrared conductivity of (Y,Pr)Ba2Cu3O7 films

The ab-plane reflectivity of (Y{1-x}Prx)Ba2Cu3O7 thin films was measured in the 30-30000 cm-1 range for samples with x = 0 (Tc = 90 K), x = 0.4 (Tc = 35 K) and x = 0.5 (Tc = 19 K) as a function of temperature in the normal state. The effective charge density obtained from the integrated spectral weight decreases with increasing x. The variation is consistent with the higher dc resistivity for x = 0.4, but is one order of magnitude smaller than what would be expected for x = 0.5. In the latter sample, the conductivity is dominated at all temperatures by a large localization peak. Its magnitude increases as the temperature decreases. We relate this peak to the dc resistivity enhancement. A simple localization-by-disorder model accounts for the optical conductivity of the x = 0.5 sample.Comment: 7 pages with (4) figures include

Comparative analysis of serine protease-related genes in the honey bee genome: possible involvement in embryonic development and innate immunity

We have identified 44 serine protease (SP) and 13 serine protease homolog (SPH) genes in the genome of Apis mellifera. Most of these genes encode putative secreted proteins, but four SPs and three SPHs may associate with the plasma membrane via a transmembrane region. Clip domains represent the most abundant non-catalytic structural units in these SP-like proteins −12 SPs and six SPHs contain at least one clip domain. Some of the family members contain other modules for protein–protein interactions, including disulphide-stabilized structures (LDL(r)A, SRCR, frizzled, kringle, Sushi, Wonton and Pan/apple), carbohydrate-recognition domains (C-type lectin and chitin-binding), and other modules (such as zinc finger, CUB, coiled coil and Sina). Comparison of the sequences with those from Drosophila led to a proposed SP pathway for establishing the dorsoventral axis of honey bee embryos. Multiple sequence alignments revealed evolutionary relationships of honey bee SPs and SPHs with those in Drosophila melanogaster, Anopheles gambiae, and Manduca sexta. We identified homologs of D. melanogaster persephone, M. sexta HP14, PAP-1 and SPH-1. A. mellifera genome includes at least five genes for potential SP inhibitors (serpin-1 through -5) and three genes of SP putative substrates (prophenoloxidase, spätzle-1 and spätzle-2). Quantitative RT-PCR analyses showed an elevation in the mRNA levels of SP2, SP3, SP9, SP10, SPH41, SPH42, SP49, serpin-2, serpin-4, serpin-5, and spätzle-2 in adults after a microbial challenge. The SP41 and SP6 transcripts significantly increased after an injection of Paenibacillus larva, but there was no such increase after injection of saline or Escherichia coli. mRNA levels of most SPs and serpins significantly increased by 48 h after the pathogen infection in 1st instar larvae. On the contrary, SP1, SP3, SP19 and serpin-5 transcript levels reduced. These results, taken together, provide a framework for designing experimental studies of the roles of SPs and related proteins in embryonic development and immune responses of A. mellifera

Exciton swapping in a twisted graphene bilayer as a solid-state realization of a two-brane model

It is shown that exciton swapping between two graphene sheets may occur under specific conditions. A magnetically tunable optical filter is described to demonstrate this new effect. Mathematically, it is shown that two turbostratic graphene layers can be described as a "noncommutative" two-sheeted (2+1)-spacetime thanks to a formalism previously introduced for the study of braneworlds in high energy physics. The Hamiltonian of the model contains a coupling term connecting the two layers which is similar to the coupling existing between two braneworlds at a quantum level. In the present case, this term is related to a K-K' intervalley coupling. In addition, the experimental observation of this effect could be a way to assess the relevance of some theoretical concepts of the braneworld hypothesis.Comment: 15 pages, 3 figures, final version published in European Physical Journal

Immune pathways and defence mechanisms in honey bees Apis mellifera

Social insects are able to mount both group-level and individual defences against pathogens. Here we focus on individual defences, by presenting a genome-wide analysis of immunity in a social insect, the honey bee Apis mellifera. We present honey bee models for each of four signalling pathways associated with immunity, identifying plausible orthologues for nearly all predicted pathway members. When compared to the sequenced Drosophila and Anopheles genomes, honey bees possess roughly one-third as many genes in 17 gene families implicated in insect immunity. We suggest that an implied reduction in immune flexibility in bees reflects either the strength of social barriers to disease, or a tendency for bees to be attacked by a limited set of highly coevolved pathogens