170 research outputs found
Living Plants in Hawaii Attacked by Coptotermes formosanus
Forty-seven species of living plants in 27 families were found infested by Coptotermes formosanus Shiraki in Hawaii. The symptoms caused by the infestations were dependent on the mode of attack. Although an actual value was not placed on the economic losses caused by the attacks, evidence indicates that the losses are substantial
Abundance and Distribution of the Three Species of Symbiotic Protozoa in the Hindgut of Coptotermes formosanus (Isoptera: Rhinotermitidae)
Workers, soldiers, nymphs and alates of the Formosan subterranean termite, Coptotermes formosanus Shiraki, all harbored the same 3 species of protozoa. Workers, nymphs, and alates had a larger number of protozoa than the soldiers. The relative abundance of the protozoa differed in the different castes. In the worker, Holomastigotoides hartmanni Koidzumi was the predominant species in numbers, followed by Pseudotrichonympha grassii Koidzumi and Spirotrichonympha leidyi Koidzumi while in the alate. S. leidyi was predominant. Each protozoan species apparently occupied a more or less specific location in the worker's hindgut. P. grassii was predominant in the first pouch, H. hartmanni in the second, and H. hartmanni and S. leidyi in the third pouch and excreta. This may indicate a difference in digestive roles of the protozoa and/or a difference in the oxygen requirements of the 3 species. There were no significant differences in the total number of protozoa found in the workers from 3 different colonies
Time varying in N=8 extended Supergravity
There has been some evidence that the fine structure "constant" may
vary with time. We point out that this variation can be described by a scalar
field in some supergravity theory in our toy model, for instance, the N=8
extended supergravity in four dimensions which can be accommodated in M-theory.Comment: 5 pages,1 figures. Accepted for publication in JHE
Limits on Cosmological Variation of Strong Interaction and Quark Masses from Big Bang Nucleosynthesis, Cosmic, Laboratory and Oklo Data
Recent data on cosmological variation of the electromagnetic fine structure
constant from distant quasar (QSO) absorption spectra have inspired a more
general discussion of possible variation of other constants. We discuss
variation of strong scale and quark masses. We derive the limits on their
relative change from (i) primordial Big-Bang Nucleosynthesis (BBN); (ii)
Oklo natural nuclear reactor, (iii) quasar absorption spectra, and (iv)
laboratory measurements of hyperfine intervals.Comment: 10 pages 2 figurs: second version have several references added and
some new comment
Towards a sensitive search for variation of the fine structure constant using radio-frequency E1 transitions in atomic dysprosium
It has been proposed that the radio-frequency electric-dipole (E1) transition
between two nearly degenerate opposite-parity states in atomic dysprosium
should be highly sensitive to possible temporal variation of the fine structure
constant () [V. A. Dzuba, V. V. Flambaum, and J. K. Webb, Phys. Rev. A
{\bf 59}, 230 (1999)]. We analyze here an experimental realization of the
proposed search in progress in our laboratory, which involves monitoring the E1
transition frequency over a period of time using direct frequency counting
techniques. We estimate that a statistical sensitivity of |\adota| \sim
10^{-18}/yr may be achieved and discuss possible systematic effects that may
limit such a measurement.Comment: 8 pages, 7 figure
Time Variations in the Scale of Grand Unification
We study the consequences of time variations in the scale of grand
unification, , when the Planck scale and the value of the unified coupling
at the Planck scale are held fixed. We show that the relation between the
variations of the low energy gauge couplings is highly model dependent. It is
even possible, in principle, that the electromagnetic coupling varies,
but the strong coupling does not (to leading approximation). We
investigate whether the interpretation of recent observations of quasar
absorption lines in terms of time variation in can be accounted for by
time variation in . Our formalism can be applied to any scenario where a
time variation in an intermediate scale induces, through threshold corrections,
time variations in the effective low scale couplings.Comment: 14 pages, revtex4; Updated observational results and improved
statistical analysis (section IV); added reference
Measuring in the Early Universe: CMB Temperature, Large-Scale Structure and Fisher Matrix Analysis
We extend our recent work on the effects of a time-varying fine-structure
constant in the cosmic microwave background, by providing a thorough
analysis of the degeneracies between and the other cosmological
parameters, and discussing ways to break these with both existing and/or
forthcoming data. In particular, we present the state-of-the-art CMB
constraints on , through a combined analysis of the BOOMERanG, MAXIMA
and DASI datasets. We also present a novel discussion of the constraints on
coming from large-scale structure observations, focusing in particular
on the power spectrum from the 2dF survey. Our results are consistent with no
variation in from the epoch of recombination to the present day, and
restrict any such (relative) variation to be less than about 4%. We show that
the forthcoming MAP and (particularly) Planck experiments will be able to break
most of the currently existing degeneracies between and other
parameters, and measure to better than percent accuracy.Comment: 11 pages in RevTex4 format. Low-quality figures to comply with arXiv
restrictions (better ones available from the authors). v2: Updated Oklo
discussion, plus other cosmetic changes. Version to appear in Phys Rev
Constraints on the Variations of the Fundamental Couplings
We reconsider several current bounds on the variation of the fine-structure
constant in models where all gauge and Yukawa couplings vary in an
interdependent manner, as would be expected in unified theories. In particular,
we re-examine the bounds established by the Oklo reactor from the resonant
neutron capture cross-section of 149Sm. By imposing variations in \Lambda_{QCD}
and the quark masses, as dictated by unified theories, the corresponding bound
on the variation of the fine-structure constant can be improved by about 2
orders of magnitude in such theories. In addition, we consider possible bounds
on variations due to their effect on long lived \alpha- and \beta-decay
isotopes, particularly 147Sm and 187Re. We obtain a strong constraint on \Delta
\alpha / \alpha, comparable to that of Oklo but extending to a higher redshift
corresponding to the age of the solar system, from the radioactive life-time of
187Re derived from meteoritic studies. We also analyze the astrophysical
consequences of perturbing the decay Q values on bound state \beta-decays
operating in the s-process.Comment: 25 pages, latex, 5 eps figure
Models of quintessence coupled to the electromagnetic field and the cosmological evolution of alpha
We study the change of the effective fine structure constant in the
cosmological models of a scalar field with a non-vanishing coupling to the
electromagnetic field. Combining cosmological data and terrestrial observations
we place empirical constraints on the size of the possible coupling and explore
a large class of models that exhibit tracking behavior. The change of the fine
structure constant implied by the quasar absorption spectra together with the
requirement of tracking behavior impose a lower bound of the size of this
coupling. Furthermore, the transition to the quintessence regime implies a
narrow window for this coupling around in units of the inverse Planck
mass. We also propose a non-minimal coupling between electromagnetism and
quintessence which has the effect of leading only to changes of alpha
determined from atomic physics phenomena, but leaving no observable
consequences through nuclear physics effects. In doing so we are able to
reconcile the claimed cosmological evidence for a changing fine structure
constant with the tight constraints emerging from the Oklo natural nuclear
reactor.Comment: 13 pages, 10 figures, RevTex, new references adde
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