3,686 research outputs found
Attraction of Acorn-Infesting \u3ci\u3eCydia Latiferreana\u3c/i\u3e (Lepidoptera: Tortricidae) to Pheromone-Baited Traps
Males of acorn-infesting Cydia latiferreana are attracted to an equilibrium mixture of the four isomers of 8, 10-dodecadien-l-ol acetate, the virgin female-produced pheromone. Trap height relative to the height of trees in which traps are placed seems to be a significant factor influencing moth catches at attractant-baited traps. In an oak woodlot and in an oak nursery, catches of male moths were greater in traps placed near the upper periphery of the canopy than at traps deployed at lower levels in the tree. Practical application of pheromone-baited traps in a forest situation will require further study on lure formulation and on trap deployment under forest conditions
Lagrangian Based Methods for Coherent Structure Detection
There has been a proliferation in the development of Lagrangian analytical methods for detecting coherent structures in fluid flow transport, yielding a variety of qualitatively different approaches. We present a review of four approaches and demonstrate the utility of these methods via their application to the same sample analytic model, the canonical double-gyre flow, highlighting the pros and cons of each approach. Two of the methods, the geometric and probabilistic approaches, are well established and require velocity field data over the time interval of interest to identify particularly important material lines and surfaces, and influential regions, respectively. The other two approaches, implementing tools from cluster and braid theory, seek coherent structures based on limited trajectory data, attempting to partition the flow transport into distinct regions. All four of these approaches share the common trait that they are objective methods, meaning that their results do not depend on the frame of reference used. For each method, we also present a number of example applications ranging from blood flow and chemical reactions to ocean and atmospheric flows. (C) 2015 AIP Publishing LLC.ONR N000141210665Center for Nonlinear Dynamic
Reionization Revisited: Secondary CMB Anisotropies and Polarization
Secondary CMB anisotropies and polarization provide a laboratory to study
structure formation in the reionized epoch. We consider the kinetic
Sunyaev-Zel'dovich effect from mildly nonlinear large-scale structure and show
that it is a natural extension of the perturbative Vishniac effect. If the gas
traces the dark matter to overdensities of order 10, as expected from
simulations, this effect is at least comparable to the Vishniac effect at
arcminute scales. On smaller scales, it may be used to study the thermal
history-dependent clustering of the gas. Polarization is generated through
Thomson scattering of primordial quadrupole anisotropies, kinetic (second order
Doppler) quadrupole anisotropies and intrinsic scattering quadrupole
anisotropies. Small scale polarization results from the density and ionization
modulation of these sources. These effects generically produce comparable E and
B-parity polarization, but of negligible amplitude (0.001-0.01 uK) in adiabatic
CDM models. However, the primordial and kinetic quadrupoles are observationally
comparable today so that a null detection of B-polarization would set
constraints on the evolution and coherence of the velocity field. Conversely, a
detection of a cosmological B-polarization even at large angles does not
necessarily imply the presence of gravity waves or vorticity. For these
calculations, we develop an all-sky generalization of the Limber equation that
allows for an arbitrary local angular dependence of the source for both scalar
and symmetric trace-free tensor fields on the sky.Comment: 14 pages, 12 figures, minor changes and typo fixes reflect published
versio
Correlation between the Mean Matter Density and the Width of the Saturated Lyman Alpha Absorption
We report a scaling of the mean matter density with the width of the
saturated Lyman alpha absorptions. This property is established using the
``pseudo-hydro'' technique (Croft et al. 1998). It provides a constraint for
the inversion of the Lyman alpha forest, which encounters difficulty in the
saturated region. With a Gaussian density profile and the scaling relation, a
simple inversion of the simulated Lyman alpha forests shows that the
one-dimensional mass power spectrum is well recovered on scales above 2 Mpc/h,
or roughly k < 0.03 s/km, at z=3. The recovery underestimates the power on
small scales, but improvement is possible with a more sophisticated algorithm.Comment: 7 pages, 9 figures, accepted for publication in MNRAS, replaced by
the version after proo
Lensing-Induced Structure of Submillimeter Sources: Implications for the Microwave Background
We consider the effect of lensing by galaxy clusters on the angular
distribution of submillimeter wavelength objects. While lensing does not change
the total flux and number counts of submillimeter sources, it can affect the
number counts and fluxes of flux-limited samples. Therefore imposing a flux cut
on point sources not only reduces the overall Poisson noise, but imprints the
correlations between lensing clusters on the unresolved flux distribution.
Using a simple model, we quantify the lensing anisotropy induced in
flux-limited samples and compare this to Poisson noise. We find that while the
level of induced anisotropies on the scale of the cluster angular correlation
length is comparable to Poisson noise for a slowly evolving cluster model, it
is negligible for more realistic models of cluster evolution. Thus the removal
of point sources is not expected to induce measurable structure in the
microwave or far-infrared backgrounds.Comment: 22 pages, 9 figures, accepted to Astrophysical Journa
Theoretical and experimental studies of the underlying processes and techniques of low pressure measurement Progress report, 1 Jun. 1966 - 31 May 1967
Construction, testing, and refining of vacuum gauges - ionization gauge cross section ratio
Cluster Correlation in Mixed Models
We evaluate the dependence of the cluster correlation length r_c on the mean
intercluster separation D_c, for three models with critical matter density,
vanishing vacuum energy (Lambda = 0) and COBE normalized: a tilted CDM (tCDM)
model (n=0.8) and two blue mixed models with two light massive neutrinos
yielding Omega_h = 0.26 and 0.14 (MDM1 and MDM2, respectively). All models
approach the observational value of sigma_8 (and, henceforth, the observed
cluster abundance) and are consistent with the observed abundance of Damped
Lyman_alpha systems. Mixed models have a motivation in recent results of
neutrino physics; they also agree with the observed value of the ratio
sigma_8/sigma_25, yielding the spectral slope parameter Gamma, and nicely fit
LCRS reconstructed spectra. We use parallel AP3M simulations, performed in a
wide box (side 360/h Mpc) and with high mass and distance resolution, enabling
us to build artificial samples of clusters, whose total number and mass range
allow to cover the same D_c interval inspected through APM and Abell cluster
clustering data. We find that the tCDM model performs substantially better than
n=1 critical density CDM models. Our main finding, however, is that mixed
models provide a surprisingly good fit of cluster clustering data.Comment: 22 pages + 10 Postscript figures. Accepted for publication in Ap
Inflation as a response to protect the Holographic Principle
A model where the inflationary phase emerges as a response to protect the
Fischler-Susskind holographic bound is described. A two fluid model in a closed
universe inflation picture is assumed, and a discussion on conditions under
which is possible to obtain an additional exponential expansion phase as those
currently observed is given.Comment: 6 pages, 2 figures. Accepted for publication in MPL
Theoretical and experimental studies of the underlying processes and techniques of low pressure measurement Letter report, 1 Jul. 1967 - 31 May 1968
Ionization gage behavior in various gas mixtures and atmospheric composition
Puromycin Sensitivity of Ribosomal Label after Incorporation of 14C-Labelled Amino Acids into Isolated Mitochondria from Neurospora crassa
Radioactive amino acids were incorporated into isolated mitochondria from Neurospora crassa. Then the mitochondrial ribosomes were isolated and submitted to density gradient centrifugation. A preferential labelling of polysomes was observed. However, when the mitochondrial suspension was treated with puromycin after amino acid incorporation, no radioactivity could be detected in either the monosomes or the polysomes. The conclusion is drawn that isolated mitochondria under these conditions do not incorporate significant amounts of amino acids into proteins of their ribosomes
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