15,968 research outputs found
Parasites of Pieris rapae L. in south-eastern Queensland
In spring, the principal parasites of Pieris rapae were Apanteles glomeratus for the larvae, and Pteromalus puparum, Brachymeria regina and Compsilura concinnata for the pupae. The highest level of parasitism by A. glomeratus was 67%, and the highest pupal parasitism was a.pproximately 63% by P. puparu
V2O5/SiO2 as an efficient catalyst in the synthesis of 5-amino- pyrazole derivatives under solvent free condition
An efficient and facile approach for the synthesis of 5-aminopyrazoles from ketene S,N-acetal and hydrazine hydrate via catalytic reaction under solvent free condition has been described. V2O5/SiO2 as a heterogeneous catalyst was prepared and characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). KEY WORDS: One-pot synthesis, 5-Amino-1H-pyrazole, Hydrazine hydrate, Vanadium oxide, Silica Bull. Chem. Soc. Ethiop. 2019, 33(1), 135-142DOI: https://dx.doi.org/10.4314/bcse.v33i1.13
Successful retrieval of competing spatial environments in humans involves hippocampal pattern separation mechanisms.
The rodent hippocampus represents different spatial environments distinctly via changes in the pattern of "place cell" firing. It remains unclear, though, how spatial remapping in rodents relates more generally to human memory. Here participants retrieved four virtual reality environments with repeating or novel landmarks and configurations during high-resolution functional magnetic resonance imaging (fMRI). Both neural decoding performance and neural pattern similarity measures revealed environment-specific hippocampal neural codes. Conversely, an interfering spatial environment did not elicit neural codes specific to that environment, with neural activity patterns instead resembling those of competing environments, an effect linked to lower retrieval performance. We find that orthogonalized neural patterns accompany successful disambiguation of spatial environments while erroneous reinstatement of competing patterns characterized interference errors. These results provide the first evidence for environment-specific neural codes in the human hippocampus, suggesting that pattern separation/completion mechanisms play an important role in how we successfully retrieve memories
Is there an imprint of Planck scale physics on inflationary cosmology?
We study the effects of the trans-Planckian dispersion relation on the
spectrum of the primordial density perturbations during inflation. In contrast
to the earlier analyses, we do not assume any specific form of the dispersion
relation and allow the initial state of the field to be arbitrary. We obtain
the spectrum of vacuum fluctuations of the quantum field by considering a
scalar field satisfying the linear wave equation with higher spatial derivative
terms propagating in the de Sitter space-time. We show that the power spectrum
does not strongly depend on the dispersion relation and that the form of the
dispersion relation does not play a significant role in obtaining the
corrections to the scale invariant spectrum. We also show that the signatures
of the deviations from the flat scale-invariant spectrum from the CMBR
observations due to quantum gravitational effects cannot be differentiated from
the standard inflationary scenario with an arbitrary initial state.Comment: 6 pages, uses RevTex4; References added; Final versio
Cosmological solutions of massive gravity on de Sitter
In the framework of the recently proposed models of massive gravity, defined
with respect to a de Sitter reference metric, we obtain new homogeneous and
isotropic solutions for arbitrary cosmological matter and arbitrary spatial
curvature. These solutions can be classified into three branches. In the first
two, the massive gravity terms behave like a cosmological constant. In the
third branch, the massive gravity effects can be described by a time evolving
effective fluid with rather remarkable features, including the property to
behave as a cosmological constant at late time.Comment: 6 pages, 1 figure; discussion extended, a few references added,
improved analysis in Section
Necessary and Sufficient Condition for Oscillations of Neutral Differential Equation
2000 Mathematics Subject Classification: 34K15, 34C10.We obtain necessary and sufficient conditions for the oscillation of all solutions of neutral differential equation with mixed (delayed and
advanced) arguments ..
Lease Accounting in Australia: Further Empirical Evidence
Key words: Australia; Accounting standard; Efficient contracting; Lease accounting; Signalling The objective of this study is to examine the economic factors motivating Australian listed lessee firms to adopt capitalization of finance leases policy from 1985 to 1987 as permitted by the transitional provision of AAS 17. Capitalization is considered as the preferred accounting policy for finance leases compared to footnote disclosure. Adopting a joint efficient contracting and quality signaling perspective, support for the research hypotheses would be construed as suggesting that capitalization is a means for lessee firms to reduce or mitigate agency and/or political costs and concurrently as a signal to the market that they are better quality firms. The sample consists of3l4 lessee firms; 67 firms as capitalizers and 247 firms as non-capitalizers. A pooled multivariate cross—sectional analysis for 1985 to 1987 was performed incorporating sensitivity analysis to determine the “best” logistic regression model. This model was then assessed to determine its validity and predictive efficacy. the results provide evidence that lessee firms adopted the capitalization as response to the media attention as being politically visible firms and concurrently as a signal to the market that they are better quality firms. The evidence also suggests limited usefulness of a lengthy transitional period
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