9,869 research outputs found
Addenda and omissions to the catalogue and checklist of the Cerambycidae and Disteniidae (Coleoptera) of the Western hemisphere
The Catalogue (Monne, 1993-1994) and Checklist (Monne and Giesbert, 1995) of the Cerambycidae and Disteniidae of the Western Hemisphere represents a necessary, and valuable tool since recompilation of Blackwelder (1946) was made. Species with references (omissions), and without them (new records) are given for some countries
The genus Erlandia Aurivillius, 1904 (Coleoptera: Cerambycidae) in Argentina, with the description of a new species
The genus Erlandia (Cerambycinae: Erlandiini) was described by Aurivillius in 1904, containing a single species, Erlandia inopinata, distributed in Bolivia, Argentina, and Paraguay. Anew species, E. megacephala, from Argentina is described, and illustrated here. A key and distribution map of both species are provided, with a generic diagnosis using characters of both species
New species, combinations, synonymies, and records of Clytini (Coleoptera: Cerambycidae)
Megacyllene (Megacyllene) cryptofrasciata n. sp. from Argentina is described and illustrated. M. quinquefasciata (Melzer, 1931), and Megacyllene rotundicollis Zajciw, 1963 are transferred from the subgenus Megacyllene Casey 1912 to Sierracyllene Tippmann, 1960. Megacyllene (SierracylZene) tafivallensis n. sp. is described from northwestern Argentina. Dexithea spixii (Laporte & Gory, 1836), and Plagionotus latreillei (Laporte & Gory, 1836) are transferred to Megacyllene (sensu stricto), excluding Dexithea, and Plagionotus from the South American fauna of Clytini. Neoclytus famelicus (Burmeister, 1865) is synonymized with N. ypsilon Chevrolat, 1861. Additional new records of Clytini from Argentina, Paraguay, and Ecuador are also presented here. A key for subgenera and species of Megacyllene is included, with distribution maps for Argentina and nearby countries
The relativistic precession of the orbits
The relativistic precession can be quickly inferred from the nonlinear polar
orbit equation without actually solving it.Comment: Accepted for publication in Astrophysics & Space Scienc
On the Space-Time Symmetries of Non-Commutative Gauge Theories
We study the space-time symmetries and transformation properties of the
non-commutative U(1) gauge theory, by using Noether charges. We carry out our
analysis by keeping an open view on the possible ways could
transform. We conclude that cannot transform under any
space-time transformation since the theory is not invariant under the conformal
transformations, with the only exception of space-time translations. The same
analysis applies to other gauge groups.Comment: 6 pages, RevTe
The impact of the new CHAMP and GRACE Earth gravity models on the measurement of the general relativistic Lense--Thirring effect with the LAGEOS and LAGEOS II satellites
Among the effects predicted by the General Theory of Relativity for the
orbital motion of a test particle, the post-Newtonian gravitomagnetic
Lense-Thirring effect is very interesting and, up to now, there is not yet an
undisputable experimental direct test of it. To date, the data analysis of the
orbits of the existing geodetic LAGEOS and LAGEOS II satellites has yielded a
test of the Lense-Thirring effect with a claimed accuracy of 20%-30%. According
to some scientists such estimates could be optimistic. Here we wish to discuss
the improvements obtainable in this measurement, in terms of reliability of the
evaluation of the systematic error and reduction of its magnitude, due to the
new CHAMP and GRACE Earth gravity models.Comment: LaTex2e, 6 pages, no figures, no tables. Paper presented at 2nd CHAMP
science meeting, Potsdam, 1-4 September 200
On the perspectives of testing the Dvali-Gabadadze-Porrati gravity model with the outer planets of the Solar System
The multidimensional braneworld gravity model by Dvali, Gabadadze and Porrati
was primarily put forth to explain the observed acceleration of the expansion
of the Universe without resorting to dark energy. One of the most intriguing
features of such a model is that it also predicts small effects on the orbital
motion of test particles which could be tested in such a way that local
measurements at Solar System scales would allow to get information on the
global properties of the Universe. Lue and Starkman derived a secular
extra-perihelion \omega precession of 5\times 10^-4 arcseconds per century,
while Iorio showed that the mean longitude \lambda is affected by a secular
precession of about 10^-3 arcseconds per century. Such effects depend only on
the eccentricities e of the orbits via second-order terms: they are, instead,
independent of their semimajor axes a. Up to now, the observational efforts
focused on the dynamics of the inner planets of the Solar System whose orbits
are the best known via radar ranging. Since the competing Newtonian and
Einsteinian effects like the precessions due to the solar quadrupole mass
moment J2, the gravitoelectric and gravitomagnetic part of the equations of
motion reduce with increasing distances, it would be possible to argue that an
analysis of the orbital dynamics of the outer planets of the Solar System, with
particular emphasis on Saturn because of the ongoing Cassini mission with its
precision ranging instrumentation, could be helpful in evidencing the predicted
new features of motion. In this note we investigate this possibility in view of
the latest results in the planetary ephemeris field. Unfortunately, the current
level of accuracy rules out this appealing possibility and it appears unlikely
that Cassini and GAIA will ameliorate the situation.Comment: LaTex, 22 pages, 2 tables, 10 figures, 27 references. Reference [17]
added, reference [26] updated, caption of figures changed, small change in
section 1.
On the effects of the Dvali-Gabadadze-Porrati braneworld gravity on the orbital motion of a test particle
In this paper we explicitly work out the secular perturbations induced on all
the Keplerian orbital elements of a test body to order O(e^2) in the
eccentricity e by the weak-field long-range modifications of the usual
Newton-Einstein gravity due to the Dvali-Gabadadze-Porrati (DGP) braneworld
model. The Gauss perturbative scheme is used. It turns out that the argument of
pericentre and the mean anomaly are affected by secular rates which are
independent of the semimajor axis of the orbit of the test particle. The first
nonvaishing eccentricity-dependent corrections are of order O(e^2). For
circular orbits the Lue-Starkman (LS) effect on the pericentre is obtained.
Some observational consequences are discussed for the Solar System planetary
mean longitudes lambda which would undergo a 1.2\cdot 10^-3 arcseconds per
century braneworld secular precession. According to recent data analysis over
92 years for the EPM2004 ephemerides, the 1-sigma formal accuracy in
determining the Martian mean longitude amounts to 3\cdot 10^-3 milliarcseconds,
while the braneworld effect over the same time span would be 1.159
milliarcseconds. The major limiting factor is the 2.6\cdot 10^-3 arcseconds per
century systematic error due to the mismodelling in the Keplerian mean motion
of Mars. A suitable linear combination of the mean longitudes of Mars and Venus
may overcome this problem. The formal, 1-sigma obtainable observational
accuracy would be \sim 7%. The systematic error due to the present-day
uncertainties in the solar quadrupole mass moment, the Keplerian mean motions,
the general relativistic Schwarzschild field and the asteroid ring would amount
to some tens of percent.Comment: LaTex2e, 23 pages, 5 tables, 1 figure, 37 references. Second-order
corrections in eccentricity explicitly added. Typos corrected. References
update
Conservative evaluation of the uncertainty in the LAGEOS-LAGEOS II Lense-Thirring test
We deal with the test of the general relativistic gravitomagnetic
Lense-Thirring effect currently ongoing in the Earth's gravitational field with
the combined nodes \Omega of the laser-ranged geodetic satellites LAGEOS and
LAGEOS II.
One of the most important source of systematic uncertainty on the orbits of
the LAGEOS satellites, with respect to the Lense-Thirring signature, is the
bias due to the even zonal harmonic coefficients J_L of the multipolar
expansion of the Earth's geopotential which account for the departures from
sphericity of the terrestrial gravitational potential induced by the
centrifugal effects of its diurnal rotation. The issue addressed here is: are
the so far published evaluations of such a systematic error reliable and
realistic? The answer is negative. Indeed, if the difference \Delta J_L among
the even zonals estimated in different global solutions (EIGEN-GRACE02S,
EIGEN-CG03C, GGM02S, GGM03S, ITG-Grace02, ITG-Grace03s, JEM01-RL03B, EGM2008,
AIUB-GRACE01S) is assumed for the uncertainties \delta J_L instead of using
their more or less calibrated covariance sigmas \sigma_{J_L}, it turns out that
the systematic error \delta\mu in the Lense-Thirring measurement is about 3 to
4 times larger than in the evaluations so far published based on the use of the
sigmas of one model at a time separately, amounting up to 37% for the pair
EIGEN-GRACE02S/ITG-Grace03s. The comparison among the other recent GRACE-based
models yields bias as large as about 25-30%. The major discrepancies still
occur for J_4, J_6 and J_8, which are just the zonals the combined
LAGEOS/LAGOES II nodes are most sensitive to.Comment: LaTex, 12 pages, 12 tables, no figures, 64 references. To appear in
Central European Journal of Physics (CEJP
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