1,790 research outputs found
The role of hawkmoth pollinators in mediating divergence and maintaining species boundaries after secondary contact in Gladiolus longiicollis
Preliminary observations of insect pollination in Protea punctata (Proteaceae)
AbstractAvailable information on the phylogeny and pollination systems in Protea suggests that bird-pollination is ancestral and occurs in the majority of species, and that there have been several shifts to rodent pollination and a single shift to pollination by cetoniine beetles in this large African genus. Here we report that Protea punctata plants in a population in the Swartberg mountains are pollinated primarily by long-proboscid flies and butterflies. The threadlike pollen presenter on an unusually flexible style facilitates insect pollination in this species. The length of the style matches that of the proboscides of its two most common visitors, the nemestrinid fly Prosoeca longipennis and the nymphalid butterfly Aeropetes tulbaghia. Spectral reflectance of the involucral bracts is similar to that of flowers of other plants visited by long-proboscid flies. P. punctata occupies a recently diverged position in a clade (the “white proteas”) in which all the other species appear to be bird-pollinated, and may represent a shift to insect pollination in the genus
Social structures and entrepreneurial networks: the strength of strong ties.
The entrepreneurial context provides a fertile arena for the study of networks. This qualitative study critically examines the nature, content and process of strong ties, which are found to fall into three categories: family, business contacts, and suppliers, competitors and customers. These nodal categories each provide a specific range of support to the entrepreneur. Their appropriate and effective utilization greatly facilitates enterprise performance
Flow equation analysis of the anisotropic Kondo model
We use the new method of infinitesimal unitary transformations to calculate
zero temperature correlation functions in the strong-coupling phase of the
anisotropic Kondo model. We find the dynamics on all energy scales including
the crossover behaviour from weak to strong coupling. The integrable structure
of the Hamiltonian is not used in our approach. Our method should also be
useful in other strong-coupling models since few other analytical methods allow
the evaluation of their correlation functions on all energy scales.Comment: 4 pages RevTeX, 2 eps figures include
Effect of route of administration of lasalocid on response of young dairy calves
Forty newborn bull calves were assigned to one of four feeding groups. The feeds
either contained lasalocid in milk (M), prestarter (PS), and starter (S); lasalocid in PS and S;
lasalocid in S only; or no lasalocid. Calves were fed M at 8% of birth weight (bw) daily and
offered PS to a maximum of 0.5 lb daily. When 0.5 lb of PS was consumed in one day the
calves were fed M at 4% of bw daily. They were weaned when they consumed dry feed at
the rate of 1.3% of bw. Daily feed intake and weekly weight gains of calves were evaluated.
Blood serum samples were used to evaluate blood metabolites at wk 4, 8, and 12. We
concluded that lasalocid in M, PS, and S supported greater feed efficiency and allowed earlier
weaning with less animal variation than when lasalocid was delivered in PS and S, only in S,
or not at all
Optimal generalization of power filters for gravitational wave bursts, from single to multiple detectors
Searches for gravitational wave signals which do not have a precise model
describing the shape of their waveforms are often performed using power
detectors based on a quadratic form of the data. A new, optimal method of
generalizing these power detectors so that they operate coherently over a
network of interferometers is presented. Such a mode of operation is useful in
obtaining better detection efficiencies, and better estimates of the position
of the source of the gravitational wave signal. Numerical simulations based on
a realistic, computationally efficient hierarchical implementation of the
method are used to characterize its efficiency, for detection and for position
estimation. The method is shown to be more efficient at detecting signals than
an incoherent approach based on coincidences between lists of events. It is
also shown to be capable of locating the position of the source.Comment: 16 pages, 5 figure
Advisory Intelligent Speed Adaptation for government fleets
This project sought to determine the likely crash savings if state government fleets in Australia were fitted with advisory Intelligent Speed Adaptation (ISA). The cost effectiveness of such a fitment was assessed considering if the ISA device is kept within the government fleet (scenario 1) or if it is left in the government vehicle when it is sold (scenario 2). Data from the fleet vehicles involved in the recent NSW ISA was used. The reduction in crash risk was calculated by applying Kloeden’s risk curves for travel speed to the “before” speed profile and the “ISA active” speed profile found in the trial. The reduction in risk was then estimated in terms of the difference in the total crash risk produced by these speed profiles. ISA was found to have the potential to reduce casualty crashes in government fleets by 20%. It was estimated that this would eliminate 171 casualty crashes involving state government vehicles per year and save $31.6 million in crash costs per year. Scenario 1 was more cost effective than scenario 2, although the wider benefit to the community produced by scenario 2 was not taken into account. Of the four ISA devices considered the navaid device that included ISA functionality was found to be the most cost effective.SD Doecke, RWG Anderson, JE Woolle
Time-frequency detection algorithm for gravitational wave bursts
An efficient algorithm is presented for the identification of short bursts of
gravitational radiation in the data from broad-band interferometric detectors.
The algorithm consists of three steps: pixels of the time-frequency
representation of the data that have power above a fixed threshold are first
identified. Clusters of such pixels that conform to a set of rules on their
size and their proximity to other clusters are formed, and a final threshold is
applied on the power integrated over all pixels in such clusters. Formal
arguments are given to support the conjecture that this algorithm is very
efficient for a wide class of signals. A precise model for the false alarm rate
of this algorithm is presented, and it is shown using a number of
representative numerical simulations to be accurate at the 1% level for most
values of the parameters, with maximal error around 10%.Comment: 26 pages, 15 figures, to appear in PR
Influence of body mass index and gender on physical activity in primary school children during PE and non-PE school days
Geotechnical causes for variations in output measured from shallow buried charges
The role of the geotechnical conditions on the impulse delivered by a shallow buried charge has received much attention in recent times. As the importance of the soil in these events has become better understood, the control over the geotechnical conditions has improved. While previous work has investigated directly the role of geotechnical conditions on the magnitude of the impulse from a buried charge, the current work aims to identify how these same conditions also affect the repeatability of testing using soils. In this paper the authors draw together their work to date for a wide range of different soil types and moisture contents to investigate the variation in output from nominally identical tests. The methodology for the preparation of soil beds and the measurement of impulse is described along with the measured variations in peak and residual deflections of a target plate fixed to the impulse measurement apparatus
- …