268 research outputs found
Aggregation of the Southern Pine Beetle in Response to Attractive Host Trees
Dendroctonus frontalis Zimmerman were attracted to shortleaf pines, Pinus echinata MilL, using infested shortleaf pine bolts. Response was monitored during the ensuing mass attack period by the use of sticky traps suspended along the tree boles. Uninfested host materials or host materials containing only male beetles did not elicit mass attack of trees. Female beetles either alone or in combination with males, usually stimulated mass attack within 24 h. Traps at 3-4 m above the ground caught the greatest number (26.7%) of beetles. Trap catches peaked on the 3rd day of attack and declined rapidly thereafter. Daily flight activity was greatest at ca. 1700 h during the summer. Male beetles outnumbered females by a ratio of 1:0.86. The sex ratio of trapped beetles varied consistently both diurnally and over the mass attack period
Field Response of the Southern Pine Beetle to Behavioral Chemicals
Field tests were conducted in East Texas in 1973-77 to evaluate the influence of 7 behavioral chemicals on the flight and landing behavior of the southern pine beetle, Dendroctonus frontalis Zimmerman. A mixture of frontalin plus host tree volatiles attracted flying beetles within an infestation. Trans-verbenol synergized the activity of frontalin and substituted for host tree volatiles, expinene and loblolly turpentine. Verbenone in a 1: 1 ratio with frontalin did not significantly affect trap catch. At higher concentrations of verbenone, trap catch was significantly reduced. Endobrevicomin inhibited trap catch when added to an attractant-baited trap. Exo-brevicomin showed no inhibitory effect. Traps with a 1:4 mixture of endo-brevicomin and verbenone plus an attractant caught significantly fewer beetles than traps with the attractant plus either one of the inhibitors
Comparisons of Supergranule Characteristics During the Solar Minima of Cycles 22/23 and 23/24
Supergranulation is a component of solar convection that manifests itself on
the photosphere as a cellular network of around 35 Mm across, with a turnover
lifetime of 1-2 days. It is strongly linked to the structure of the magnetic
field. The horizontal, divergent flows within supergranule cells carry local
field lines to the cell boundaries, while the rotational properties of
supergranule upflows may contribute to the restoration of the poloidal field as
part of the dynamo mechanism that controls the solar cycle. The solar minimum
at the transition from cycle 23 to 24 was notable for its low level of activity
and its extended length. It is of interest to study whether the convective
phenomena that influences the solar magnetic field during this time differed in
character to periods of previous minima. This study investigates three
characteristics (velocity components, sizes and lifetimes) of solar
supergranulation. Comparisons of these characteristics are made between the
minima of cycles 22/23 and 23/24 using MDI Doppler data from 1996 and 2008,
respectively. It is found that whereas the lifetimes are equal during both
epochs (around 18 h), the sizes are larger in 1996 (35.9 +/- 0.3 Mm) than in
2008 (35.0 +/- 0.3 Mm), while the dominant horizontal velocity flows are weaker
(139 +/- 1 m/s in 1996; 141 +/- 1 m/s in 2008). Although numerical differences
are seen, they are not conclusive proof of the most recent minimum being
inherently unusual.Comment: 22 pages, 5 figures. Solar Physics, in pres
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Chemical derivation to enhance the chemical/oxidative stability of resorcinol-formaldehyde (R-F) resin
Tank wastes at Hanford and SRS contain highly alkaline supernate solutions of conc. Na, K nitrates with large amounts of {sup 137}Cs. It is desirable to remove and concentrate the highly radioactive fraction for vitrification. One candidate ion exchange material for removing the radiocesium is R-F resin. This report summarizes studies into synthesis and characterization of 4-derivatized R-F resins prepared in pursuit of more chemically/oxidatively robust resin. 85% 4-fluororesorcinol/15% phenol formaldehyde resin appears to have good stability in alkaline solution, although there may be some nucleophilic displacement reaction during synthesis; further studies are needed
Validation of enzyme immunoassays via an adrenocorticotrophic stimulation test for the non-invasive quantification of stress-related hormone metabolites in naked mole-rats
DATA AVAILABILITY: Data supporting the reported results will be sent by the corresponding
author upon request.SUPPLEMENTARY MATERIALS : TABLE S1: Summary of saline volume and synthetic
adrenocorticotropic hormone (Synacthen® depot, Novartis, South Africa (Pty) Ltd.) administered to
each individual during the ACTH challenge; TABLE S2: Summary of EIA sensitivities and intra-assay
and inter-assay coefficients of variation in high- and low-value quality controls for all EIAs applied to
measure immunoreactive urine glucocorticoid metabolite (uGCM) and fecal glucocorticoid metabolite
in naked mole-rats.Small size in mammals usually restricts long-term, frequent monitoring of endocrine
function using plasma as a matrix. Thus, the non-invasive monitoring of hormone metabolite
concentrations in excreta may provide an invaluable approach. The aim of the current study was
to examine the suitability of enzyme immunoassays (EIAs) for monitoring responses to stressors
in the naked mole-rat (Heterocephalus glaber, NMR) using urine and feces as hormone matrices.
A saline control administration, and a high- and low-dose adrenocorticotropic hormone (ACTH)
challenge were performed on six male and six female disperser morph NMRs. The results revealed
that a 5α-pregnane-3β,11β,21-triol-20-one EIA detecting glucocorticoid metabolites (GCMs) with
a 5α-3β-11β-diol structure is the most suitable assay for measuring concentrations in male urine
samples, whereas an 11-oxoaetiocholanolone EIA detecting GCMs with a 5β-3α-ol-11-one structure
appears the most suitable EIA for quantifying GCMs in female urine. An 11-oxoaetiocholanolone
EIA detecting 11,17 dioxoandrostanes was the most suitable EIA for quantifying GCMs in the feces of
both sexes. There were sex-related differences in response to the high- and low-dose ACTH challenge.
We recommend using feces as a more suitable matrix for non-invasive GCM monitoring for NMRs
which can be valuable when investigating housing conditions and other welfare aspects.SARChI Chair of Mammalian Behavioral Ecology and Physiology from the DST–NRF South Africa and the National Research Foundation.https://www.mdpi.com/journal/animalsMammal Research InstituteZoology and Entomolog
Subsurface Supergranular Vertical Flows as Measured Using Large Distance Separations in Time-Distance Helioseismology
As large--distance rays (say, 10\,-\,) approach the solar surface
approximately vertically, travel times measured from surface pairs for these
large separations are mostly sensitive to vertical flows, at least for shallow
flows within a few Mm of the solar surface. All previous analyses of
supergranulation have used smaller separations and have been hampered by the
difficulty of separating the horizontal and vertical flow components. We find
that the large separation travel times associated with supergranulation cannot
be studied using the standard phase-speed filters of time-distance
helioseismology. These filters, whose use is based upon a refractive model of
the perturbations, reduce the resultant travel time signal by at least an order
of magnitude at some distances. More effective filters are derived. Modeling
suggests that the center--annulus travel time difference
in the separation range \,-\, is insensitive to the
horizontally diverging flow from the centers of the supergranules and should
lead to a constant signal from the vertical flow. Our measurement of this
quantity, 5.1 \pm 0.1\secs, is constant over the distance range. This
magnitude of signal cannot be caused by the level of upflow at cell centers
seen at the photosphere of 10\ms extended in depth. It requires the vertical
flow to increase with depth. A simple Gaussian model of the increase with depth
implies a peak upward flow of 240\ms at a depth of 2.3\Mm and a peak
horizontal flow of 700\ms at a depth of 1.6\Mm.Comment: Solar Physics; 15 pages, 6 figure
Aggression, boldness, and exploration personality traits in the subterranean naked mole-rat (Heterocephalus glaber) disperser morphs
Animal personality traits (consistent behavioral differences between individuals in their
behavior across time and/or situation) affect individual fitness through facets, such as dispersal. In
eusocial naked mole-rat (Heterocephalus glaber) colonies, a disperser morph may arise with distinct
morphological, behavioral, and physiological characteristics. This study aimed to quantify the
personality traits of a cohort of disperser morphs of naked mole-rat (NMR). Behavioral tests were
performed on twelve disperser morphs (six males and six females) in an observation tunnel system
that was novel and unfamiliar. Novel stimuli (fresh snakeskin, tissue paper, and conspecific of the
same sex) were introduced for fifteen minutes, and the behavioral acts of the individual were recorded.
A total of 30 behaviors were noted during the behavioral tests of which eight were used to quantify
aggression, boldness, and exploration. The NMR disperser morphs showed consistent individual
differences in boldness, and exploration across time and test, indicating a distinct personality. In
addition, new naked mole-rat responses including disturbance behaviors; confront, barricade, and
stay-away, were recorded. Further investigations into the relationships between animal personality
traits and social hierarchy position in entire colonies are needed for more informative results as we
further investigate the role of personality in cooperatively breeding societies.The SARChI Chair of Mammalian Behavioral Ecology and Physiology from the DST–NRF South Africa, the National Research Foundation, and the University of Pretoria. J.U.M Jarvis, G. Lewin and A. Barker for equipment donation.https://www.mdpi.com/journal/animalsam2023Zoology and Entomolog
Electron energy loss and induced photon emission in photonic crystals
The interaction of a fast electron with a photonic crystal is investigated by
solving the Maxwell equations exactly for the external field provided by the
electron in the presence of the crystal. The energy loss is obtained from the
retarding force exerted on the electron by the induced electric field. The
features of the energy loss spectra are shown to be related to the photonic
band structure of the crystal. Two different regimes are discussed: for small
lattice constants relative to the wavelength of the associated electron
excitations , an effective medium theory can be used to describe the
material; however, for the photonic band structure plays an
important role. Special attention is paid to the frequency gap regions in the
latter case.Comment: 12 pages, 7 figure
BAs and boride III-V alloys
Boron arsenide, the typically-ignored member of the III-V arsenide series
BAs-AlAs-GaAs-InAs is found to resemble silicon electronically: its Gamma
conduction band minimum is p-like (Gamma_15), not s-like (Gamma_1c), it has an
X_1c-like indirect band gap, and its bond charge is distributed almost equally
on the two atoms in the unit cell, exhibiting nearly perfect covalency. The
reasons for these are tracked down to the anomalously low atomic p orbital
energy in the boron and to the unusually strong s-s repulsion in BAs relative
to most other III-V compounds. We find unexpected valence band offsets of BAs
with respect to GaAs and AlAs. The valence band maximum (VBM) of BAs is
significantly higher than that of AlAs, despite the much smaller bond length of
BAs, and the VBM of GaAs is only slightly higher than in BAs. These effects
result from the unusually strong mixing of the cation and anion states at the
VBM. For the BAs-GaAs alloys, we find (i) a relatively small (~3.5 eV) and
composition-independent band gap bowing. This means that while addition of
small amounts of nitrogen to GaAs lowers the gap, addition of small amounts of
boron to GaAs raises the gap (ii) boron ``semi-localized'' states in the
conduction band (similar to those in GaN-GaAs alloys), and (iii) bulk mixing
enthalpies which are smaller than in GaN-GaAs alloys. The unique features of
boride III-V alloys offer new opportunities in band gap engineering.Comment: 18 pages, 14 figures, 6 tables, 61 references. Accepted for
publication in Phys. Rev. B. Scheduled to appear Oct. 15 200
Large-scale horizontal flows in the solar photosphere. IV. On the vertical structure of large-scale horizontal flows
In the recent papers, we introduced a method utilised to measure the flow
field. The method is based on the tracking of supergranular structures. We did
not precisely know, whether its results represent the flow field in the
photosphere or in some sub-photospheric layers. In this paper, in combination
with helioseismic data, we are able to estimate the depths in the solar
convection envelope, where the detected large-scale flow field is well
represented by the surface measurements. We got a clear answer to question what
kind of structures we track in full-disc Dopplergrams. It seems that in the
quiet Sun regions the supergranular structures are tracked, while in the
regions with the magnetic field the structures of the magnetic field are
dominant. This observation seems obvious, because the nature of Doppler
structures is different in the magnetic regions and in the quiet Sun. We show
that the large-scale flow detected by our method represents the motion of
plasma in layers down to ~10 Mm. The supergranules may therefore be treated as
the objects carried by the underlying large-scale velocity field.Comment: 8 pages, 5 figures, accepted in New Astronom
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