29,408 research outputs found
A hard coat, a tough choice? The effects of host seed morphology and mechanics on the egg laying behaviour of the bruchid beetle, Callosobruchus maculatus.
This study investigated whether the egg laying behaviour of Callosobruchus maculatus, an important storage pest of leguminous seed crops, was related to the mechanical properties of the host seed. The hypothesis was that females avoid laying eggs on seeds with particularly tough seed coats and hard cotyledons to reduce the resistance their larvae are subjected to when they bore into the seed to complete their development.
Females were presented with seeds from three leguminous species: Vigna unguiculata, V. angularis and V. radiata. The distribution of oviposition sites on the seed's surface was related to the morphology and mechanical properties of the seed. Vickers microhardness and fracture tests were used to investigate regional variation and compare the properties of seeds with and without eggs adhered to their surface.
There were no significant regional differences in the hardness of the cotyledon material along the longitudinal axis of the seed (P > 0.05). However, there were significant differences between the mechanical properties of the seed coat and the cotyledons; in V. unguiculata the seed coat was tougher, 1249 Ā± 80.8 J mā2, than the cotyledons, 402 Ā± 30.0 J mā2 (P 0.05). Mechanical data are discussed in relation to the egg laying behaviour of C. maculatus
A VIEW FROM THE GROUND: A REFORM GROUPāS PERSPECTIVE ON THE ONGOING EFFORT TO ACHIEVE MERIT SELECTION OF JUDGES
This article describes the history of judicial selection in the state of Pennsylvania. It describes the judicial selection reform movement and the growth of the organization Pennsylvanians for Modern Courts ( PMC ) which devises solutions to meet the various challenges to judicial integrity in Pennsylvania. It focuses on the merit system that PMC has been trying to achieve for Pennsylvania\u27s appellate courts
Enhancement of second-order nonlinear-optical signals by optical stimulation
Second-order nonlinear optical interactions such as sum- and
difference-frequency generation are widely used for bioimaging and as selective
probes of interfacial environments. However, inefficient nonlinear optical
conversion often leads to poor signal-to-noise ratio and long signal
acquisition times. Here, we demonstrate the dramatic enhancement of weak
second-order nonlinear optical signals via stimulated sum- and
difference-frequency generation. We present a conceptual framework to
quantitatively describe the interaction and show that the process is highly
sensitive to the relative optical phase of the stimulating field. To emphasize
the utility of the technique, we demonstrate stimulated enhancement of second
harmonic generation (SHG) from bovine collagen-I fibrils. Using a stimulating
pulse fluence of only 3 nJ/cm2, we obtain an SHG enhancement >10^4 relative to
the spontaneous signal. The stimulation enhancement is greatest in situations
where spontaneous signals are the weakest - such as low laser power, small
sample volume, and weak nonlinear susceptibility - emphasizing the potential
for this technique to improve signal-to-noise ratios in biological imaging and
interfacial spectroscopy
Living standards, inequality and poverty
In this Election Briefing Note, we assess what has happened to living standards under Labour, setting out how average incomes, income inequality and poverty have changed since 1996- 97. We compare these changes with what happened under previous governments, and highlight where there have been differences between Labour's first and second terms
Poverty and inequality in Britain: 2005
This Commentary provides an update on trends in poverty and inequality in Great Britain, based on the latest official government statistics. It uses the same approach to measuring incomes and poverty in Great Britain as the government employs in its Households Below Average Income (HBAI) publication
Statistics of the Mesoscopic Field
We find in measurements of microwave transmission through quasi-1D dielectric
samples for both diffusive and localized waves that the field normalized by the
square root of the spatially averaged flux in a given sample configuration is a
Gaussian random process with position, polarization, frequency, and time. As a
result, the probability distribution of the field in the random ensemble is a
mixture of Gaussian functions weighted by the distribution of total
transmission, while its correlation function is a product of correlators of the
Gaussian field and the square root of the total transmission.Comment: RevTex: 5 pages, 2 figures; to be presented at Aspects of Quantum
Chaotic Scattering (Dresden, March 7-12, 2005
Poverty and inequality in Britain: 2006
This Commentary provides an update on trends in poverty and inequality in Great Britain, based on the latest official government statistics. It uses the same approach to measuring incomes and poverty in Great Britain as the government employs in its Households Below Average Income (HBAI) publication
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