675 research outputs found
Probing large distance higher dimensional gravity from lensing data
The modifications induced in the standard weak-lensing formula if Newtonian
gravity differs from inverse square law at large distances are studied. The
possibility of putting bounds on the mass of gravitons from lensing data is
explored. A bound on graviton mass, esitmated to be about 100 Mpc is
obtained from analysis of some recent data on gravitational lensing.Comment: 6 pages, 1 figure, added reference
Electric dipole rovibrational transitions in HD molecule
The rovibrational electric dipole transitions in the ground electronic state
of the HD molecule are studied. A simple, yet rigorous formula is derived for
the transition rates in terms of the electric dipole moment function ,
which is calculated in a wide range of . Our numerical results for
transition rates are in moderate agreement with experiments and previous
calculations, but are at least an order of magnitude more accurate.Comment: 7 pages, 1 figur
The second fossil species of <i>Cathartosilvanus</i> (Coleoptera: Cucujoidea: Silvanidae) from Eocene Baltic amber
A new fossil species of the silvanid flat bark beetle genus
Cathartosilvanus Grouvelle is described and illustrated from Baltic amber. Cathartosilvanus siteiterralevis sp. nov. differs
from recent and fossil congeners in the distinct, sharp denticle found along
its posterior pronotal angle. The phenomenon of specific body parts becoming
disconnected, and the compression of specimens is briefly discussed and
interpreted in the context of amber taphonomy. The specimen under study
appears to be an uncommon case of a weakly sclerotized beetle imago becoming
entrapped in resin shortly after moulting.</p
Spectator Effects in the Decay B -> K \gamma \gamma
We report the results of the first computation related to the study of the
spectator effects in the rare decay mode within the
framework of Standard Model. It is found that the account of these effects
results in the enhancement factor for the short-distance reducible contribution
to the branching ratio.Comment: 5 pages, 5 figures, RevTeX
A new trap-jawed ant (Hymenoptera: Formicidae: Haidomyrmecini) from Canadian Late Cretaceous amber
This is the publisher's version, also available electronically from http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8953790&fileId=S0008347X13000230A new genus and species are described within the extinct tribe Haidomyrmecini, and tentatively placed within the subfamily Sphecomyrminae (Hymenoptera: Formicidae). Haidoterminus cippus new genus and species expands the distribution of the bizarre, exclusively Cretaceous, trap-jawed Haidomyrmecini beyond their previous records in mid-Cretaceous Burmese and French amber, and into Laurentia. The new material from the Grassy Lake, Alberta, Canada collecting locality also provides evidence that these highly specialised, likely arboreal, ants persisted for an additional 20 million years, reaching the Late Cretaceous. Morphological features of H. cippus, such as the presence of an elongate antennomere II (pedicel), further support the argument that Haidomyrmecini may not actually belong within the subfamily Sphecomyrminae, and may warrant recognition at the subfamily level or inclusion as a highly autapomorphic clade within another subfamily. Despite the introduction of new fossil material, and the clarity of preservation in Canadian amber, the mystery of how Haidomyrmecini fed remains unsolved
The first described turtle beetles from Eocene Baltic amber, with notes on fossil Chelonariidae (Coleoptera: Byrrhoidea)
Chelonariidae, or turtle beetles, are rarely represented in the
fossil record. Two new extinct species of this thermophilous coleopteran
family, Chelonarium andabata Alekseev and Bukejs sp. nov. and Ch. dingansich Alekseev and Bukejs sp. nov., are described and illustrated from Eocene Baltic amber using
X-ray micro-computed tomography (micro-CT). They are the first formally
described species of turtle beetles from Eocene Baltic amber and the first
known European representatives of this family. Based on modern habitats of
the group, the presence of the plants with which their larvae are associated
(epiphytic orchids) is proposed in the Eocene amber forest. The Eocene
Florissant Formation fossil Chelonarium montanum Wickham, 1914, which was originally placed within
Chelonariidae, is discussed based on its original description, and placement
as incertae sedis within Byrrhoidea is proposed for this compression fossil
(http://zoobank.org/References/C2EE164D-59DD-42FE-937D-B01C78DCD228, last access: 8 February 2021).</p
Infrared spectra of the water-CO2 complex in the 4.3-3.6 micron region and determination of the ground state tunneling splitting for HDO-CO2
Spectra of water-CO2 dimers are studied using a tunable mid-infrared source
to probe a pulsed slit jet supersonic expansion. H2O-CO2 and D2O-CO2 are
observed in the CO2 nu3 fundamental region (~2350 cm-1), D2O-CO2 is also
observed in the D2O nu3 fundamental region (~2790 cm-1), and HDO-CO2 is
observed in the HDO O-D stretch fundamental region (~2720 cm-1), all for the
first time in these regions. Analysis of the spectra yields excited state
rotational parameters and vibrational shifts. They also yield the first
experimental values of the ground state internal rotation tunneling splittings
for D2O-CO2 (0.003 cm-1) and HDO-CO2 (0.0234 cm-1). The latter value is a
direct determination made possible by the reduced symmetry of HDO-CO2. These
results provide stringent and easily interpreted tests for theoretical water -
CO2 potential energy surface calculations.Comment: 19 pages, 6 figure and 5 table
Inelastic Diffraction and Spectroscopy of Very Weakly Bound Clusters
We study the coherent inelastic diffraction of very weakly bound two body
clusters from a material transmission grating. We show that internal
transitions of the clusters can lead to new separate peaks in the diffraction
pattern whose angular positions determine the excitation energies. Using a
quantum mechanical approach to few body scattering theory we determine the
relative peak intensities for the diffraction of the van der Waals dimers
(D_2)_2 and H_2-D_2. Based on the results for these realistic examples we
discuss the possible applications and experimental challenges of this coherent
inelastic diffraction technique.Comment: 15 pages + 5 figures. J. Phys. B (in press
The cobalt(II) salt of the azo dye Orange G
Crystallizing the cobalt(II) salt of the azo dye Orange G from water was found to give the solvent-separated ion-pair species hexaaquacobalt(II) 7-oxo-8-(2-phenylhydrazin-1-ylidene)-7,8-dihydronaphthalene-1,3-disulfonate tetrahydrate, [Co(H2O)6](C16H10N2O7S2)·4H2O. The asymmetric unit of the cobalt(II) salt contains three independent octahedral [Co(OH2)6]2+ cations, three azo anions, all with similar configurations, and 12 uncoordinated water molecules. The structure is closely related to that of one of the known magnesium analogues. Both structures have Z′ = 3, feature nearly planar azo anions [maximum displacement of azo-N atoms from the plane of the phenyl ring = 0.058 (7) Å] in their hydrazone tautomeric form, form layer structures with hydrophilic and hydrophobic layers alternating along the b-axis direction, and are stabilized by an extensive network of hydrogen bonds.
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