2,189 research outputs found
Trap Response of Michigan Social Wasps (Hymenoptera: Vespidae) to the Feeding Attractants Acetic Acid, Isobutanol, and Heptyl Butyrate.
Nine species of social wasps were captured in traps baited with acetic acid, isobutanol, heptyl butyrate and combinations of acetic acid and either isobutanol or heptyl butyrate. Three yellowjacket species in the Vespula rufa species group were captured in traps (Vespula acadica (Sladen), Vespula consobrina (Saussure), Vespula vidua (Saussure)). They responded similarly, with attraction only to heptyl butyrate. Three yellowjacket species in the Vespula vulgaris species group were also captured in traps (Vespula vulgaris (L.), Vespula flavorpilosa Jacobson, Vespula maculifrons (Buyyson)). They responded similarly, with attraction primarily to the combination of acetic acid and isobutanol. The bald-faced hornet, Dolichovespula maculata (L.), was attracted to acetic acid and was more strongly attracted to the combination of acetic acid and isobutanol. The aerial yellowjacket, Dolichovespula arenaria (Fabr.), was attracted to isobutanol, and was more strongly attracted to the combination of acetic acid and isobutanol. These results add to our understanding of how to target various species of social wasps with chemical lures
NGC 6738: not a real open cluster
A photometric, astrometric and spectroscopic investigation of the poorly
studied open cluster NGC 6738 has been performed in order to ascertain its real
nature. NGC 6738 is definitely not a physical stellar ensemble: photometry does
not show a defined mean sequence, proper motions and radial velocities are
randomly distributed, spectro-photometric parallaxes range between 10 and 1600
pc, and the apparent luminosity function is identical to that of the
surrounding field. NGC 6738 therefore appears to be an apparent concentration
of a few bright stars projected on patchy background absorption.Comment: A&A, in press (compared with first submission to astro-ph, now Table
2 and Figure 4 are replaced with corrected versions
Worker policing by egg eating in the ponerine ant Pachycondyla inversa
We investigated worker policing by egg eating in the ponerine ant Pachycondyla inversa, a species with
morphologically distinct queens and workers. Colonies were split into one half with the queen and one
half without. Workers in queenless colony fragments started laying unfertilized male eggs after three weeks.
Worker-laid eggs and queen-laid eggs were introduced into five other queenright colonies with a single
queen and three colonies with multiple queens, and their fate was observed for 30 min. Significantly more
worker-laid eggs (range of 35–62%, mean of 46%) than queen-laid eggs (range of 5–31%, mean of 15%)
were eaten by workers in single-queen colonies, and the same trend was seen in multiple-queen colonies.
This seems to be the first well-documented study of ants with a distinct caste polymorphism to show that
workers kill worker-laid eggs in preference to queen-laid eggs. Chemical analyses showed that the surfaces
of queen-laid and worker-laid eggs have different chemical profiles as a result of different relative proportions
of several hydrocarbons. Such differences might provide the information necessary for differential
treatment of eggs. One particular alkane, 3,11-dimeC27, was significantly more abundant on the surfaces
of queen-laid eggs. This substance is also the most abundant compound on the cuticles of egg layers
Unusual cavity shapes resulting from multistep mass transport controlled dissolution: Numerical simulation and experimental investigation with titanium using oxide film laser lithography
The shape evolution of cavities produced by multistep electrochemical micromachining is investigated both theoretically and experimentally. A boundary element code is used for 2D simulation of the shape evolution as a function of applied charge. A two-step process is simulated by assuming that metal dissolves from a small area at the bottom of a hemicylindrical groove protected by an insulating film. Similarly, the shape evolution in a three-step process is numerically simulated. The simulation shows that multistep isotropic etching can yield buried cavities with a narrow opening as well as large aspect ratio cavities. It also permits one to achieve aspect ratios larger than one. Electrochemical micromachining experiments were carried out with titanium using oxide film laser lithography (OFLL) for patterning the surface. Metal dissolution from the irradiated line features on the oxide was carried out in an electropolishing electrolyte starting from a flat surface or from preformed grooves. The resulting cavity shapes observed with a microscope corresponded well to the theoretical predictions. The experiments thus confirmed that isotropic etching involving two or three subsequent anodization-irradiation-dissolution steps can yield high aspect ratio cavities and partly occluded cavities. Possible implications of the present results for the shape evolution of corrosion pits are discusse
Trap Response of Michigan Social Wasps (Hymenoptera: Vespidae) to the Feeding Attractants Acetic Acid, Isobutanol, and Heptyl Butyrate.
Nine species of social wasps were captured in traps baited with acetic acid, isobutanol, heptyl butyrate and combinations of acetic acid and either isobutanol or heptyl butyrate. Three yellowjacket species in the Vespula rufa species group were captured in traps (Vespula acadica (Sladen), Vespula consobrina (Saussure), Vespula vidua (Saussure)). They responded similarly, with attraction only to heptyl butyrate. Three yellowjacket species in the Vespula vulgaris species group were also captured in traps (Vespula vulgaris (L.), Vespula flavorpilosa Jacobson, Vespula maculifrons (Buyyson)). They responded similarly, with attraction primarily to the combination of acetic acid and isobutanol. The bald-faced hornet, Dolichovespula maculata (L.), was attracted to acetic acid and was more strongly attracted to the combination of acetic acid and isobutanol. The aerial yellowjacket, Dolichovespula arenaria (Fabr.), was attracted to isobutanol, and was more strongly attracted to the combination of acetic acid and isobutanol. These results add to our understanding of how to target various species of social wasps with chemical lures
Photometric Calibration of the Supernova Legacy Survey Fields
We present the photometric calibration of the Supernova Legacy Survey (SNLS)
fields. The SNLS aims at measuring the distances to SNe Ia at (0.3<z<1) using
MegaCam, the 1 deg^2 imager on the Canada-France-Hawaii Telescope (CFHT). The
uncertainty affecting the photometric calibration of the survey dominates the
systematic uncertainty of the key measurement of the survey, namely the dark
energy equation of state. The photometric calibration of the SNLS requires
obtaining a uniform response across the imager, calibrating the science field
stars in each survey band (SDSS-like ugriz bands) with respect to standards
with known flux in the same bands, and binding the calibration to the UBVRI
Landolt standards used to calibrate the nearby SNe from the literature
necessary to produce cosmological constraints. The spatial non-uniformities of
the imager photometric response are mapped using dithered observations of dense
stellar fields. Photometric zero-points against Landolt standards are obtained.
The linearity of the instrument is studied. We show that the imager filters and
photometric response are not uniform and publish correction maps. We present
models of the effective passbands of the instrument as a function of the
position on the focal plane. We define a natural magnitude system for MegaCam.
We show that the systematics affecting the magnitude-to-flux relations can be
reduced if we use the spectrophotometric standard star BD +17 4708 instead of
Vega as a fundamental flux standard. We publish ugriz catalogs of tertiary
standards for all the SNLS fields.Comment: 46 pages, 23 figures. Accepted by Astronomy and Astrophysics. Online
material available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr
(130.79.128.5) or http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ or
alternatively from: http://supernovae.in2p3.fr/snls3/regnault09_cds.tar.g
Huge Seebeck coefficients in non-aqueous electrolytes
The Seeebeck coefficients of the non-aqueous electrolytes tetrabutylammonium
nitrate, tetraoctylphosphonium bromide and tetradodecylammonium nitrate in
1-octanol, 1-dodecanol and ethylene-glycol are measured in a temperature range
from T=30 to T=45 C. The Seebeck coefficient is generally of the order of a few
hundreds of microvolts per Kelvin for aqueous solution of inorganic ions. Here
we report huge values of 7 mV/K at 0.1M concentration for tetrabutylammonium
nitrate in 1-dodecanol. These striking results open the question of
unexpectedly large kosmotrope or "structure making" effects of
tetraalkylammonium ions on the structure of alcohols.Comment: Submitted to J. Chem. Phy
Interatomic potentials for the vibrational properties of III-V semiconductor nanostructures
We derive interatomic potentials for zinc blende InAs, InP, GaAs and GaP
semiconductors with possible applications in the realm of nanostructures. The
potentials include bond stretching interaction between the nearest and
next-nearest neighbors, a three body term and a long-range Coulomb interaction.
The optimized potential parameters are obtained by (i) fitting to bulk phonon
dispersions and elastic properties and (ii) constraining the parameter space to
deliver well behaved potentials for the structural relaxation and vibrational
properties of nanostructure clusters. The targets are thereby calculated by
density functional theory for clusters of up to 633 atoms. We illustrate the
new capability by the calculation Kleinman and Gr\"uneisen parameters and of
the vibrational properties of nanostructures with 3 to 5.5 nm diameter.Comment: 22 pages, 5 figures; Phys. Rev. B 201
Magnetic properties of HO2 thin films
We report on the magnetic and transport studies of hafnium oxide thin films
grown by pulsed-laser deposition on sapphire substrates under different oxygen
pressures, ranging from 10-7 to 10-1 mbar. Some physical properties of these
thin films appear to depend on the oxygen pressure during growth: the film
grown at low oxygen pressure (P ~= 10-7 mbar) has a metallic aspect and is
conducting, with a positive Hall signal, while those grown under higher oxygen
pressures (7 x 10-5 <= P <= 0.4 mbar) are insulating. However, no intrinsic
ferromagnetic signal could be attributed to the HfO2 films, irrespective of the
oxygen pressure during the deposition.Comment: 1
The large amplitude outburst of the young star HBC 722 in NGC 7000/IC 5070, a new FU Orionis candidate
We report the discovery of a large amplitude outburst from the young star HBC
722 (LkHA 188 G4) located in the region of NGC 7000/IC 5070. On the basis of
photometric and spectroscopic observations, we argue that this outburst is of
the FU Orionis type. We gathered photometric and spectroscopic observations of
the object both in the pre-outburst state and during a phase of increase in its
brightness. The photometric BVRI data (Johnson-Cousins system) that we present
were collected from April 2009 to September 2010. To facilitate transformation
from instrumental measurements to the standard system, fifteen comparison stars
in the field of HBC 722 were calibrated in the BVRI bands. Optical spectra of
HBC 722 were obtained with the 1.3-m telescope of Skinakas Observatory (Crete,
Greece) and the 0.6-m telescope of Schiaparelli Observatory in Varese (Italy).
The pre-outburst photometric and spectroscopic observations of HBC 722 show
both low amplitude photometric variations and an emission-line spectrum typical
of T Tau stars. The observed outburst started before May 2010 and reached its
maximum brightness in September 2010, with a recorded Delta V~4.7 mag.
amplitude. Simultaneously with the increase in brightness the color indices
changed significantly and the star became appreciably bluer. The light curve of
HBC 722 during the period of rise in brightness is similar to the light curves
of the classical FUors - FU Ori and V1057 Cyg. The spectral observations during
the time of increase in brightness showed significant changes in both the
profiles and intensity of the spectral lines. Only H alpha remained in
emission, while the H beta, Na I 5890/5896, Mg I triplet 5174, and Ba II
5854/6497 lines were in strong absorption.Comment: 4 pages, 6 figures, accepted for publication in A&
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