4,370 research outputs found
Genetic Similarities Among Geographic Isolates of Lysiphlebus testaceipes (Hymenoptera: Aphidiidae) Differing in Cold Temperature Tolerances
Lysiphlebus testaceipes (Cresson) is a solitary endoparasitoid of aphids and is the primary parasitoid attacking cereal aphids in the Great Plains, especially Schizaphis graminum (Rondani). In a previous study, it was found that a Lincoln, NE, isolate of L. testaceipes had a much higher survivorship at cold temperatures than isolates from Stillwater, OK, and Corpus Christi, TX. This suggested that the Nebraska isolate was locally adapted to the northern environment and perhaps genetically divergent from southern populations. We tested for genetic differentiation of the above isolates by sequencing portions of the COI and 16S mtDNA genes. We also examined a Florida isolate reared from Toxoptera citricida (Kirkaldy) and L. fabarum Marshall as an outgroup. The Great Plains isolates (Nebraska, Oklahoma, and Texas) were homogeneous with 0% and 0Ð0.2% sequence divergence in the COI and 16S gene fragments, respectively. The Florida isolate differed from the Great Plains isolates in nucleotide sequence by 1.4% (COI) and 0.5Ð0.7% (16S). Phylogenetic analysis placed the Florida isolate of L. testaceipes basal to the Great Plains isolates with L. fabarum, suggesting a possible species complex within L. testaceipes
Annona muricata (graviola): toxic or therapeutic
This paper examines annona muricata (graviola): toxic or therapeutic
Oil quality in diesel engines with on line oil cleaning using a heated lubricating oil recycler
A method of cleaning the oil on line was investigatedusing a bypass fine particulate filter followed by an infra
red heater to remove water and light diesel fractions in
the oil. This was tested on a range of on road vehicles
and a Ford 1.8 litre IDI passenger car engine on a test
bed. Comparison was made with the oil quality on the
same vehicles and engines without the on-line recycler.
Test times were from 200 to 1500 hours of oil ageing and
some of the tests showed that the oil quality was still
good after 4 times the normal oil life. The results showed
that the on line oil recycler cleaning system reduced the
rate of fall of the TBN and rate of increase of the TAN.
There was a very significant reduction in the soot in oil
and the fuel dilution. There was also a consistent reduction
in all the wear metals apart from copper and a
decrease in the rate of reduction of oil additives. There
was also measured on the Ford IDI engine a 5% reduced
fuel consumption. Many of these effects were attributed
to an influence of the cleaner oil on reduced engine
deposits
Oil quality in diesel engines with on line oil cleaning using a heated lubricating oil recycler
A method of cleaning the oil on line was investigatedusing a bypass fine particulate filter followed by an infra
red heater to remove water and light diesel fractions in
the oil. This was tested on a range of on road vehicles
and a Ford 1.8 litre IDI passenger car engine on a test
bed. Comparison was made with the oil quality on the
same vehicles and engines without the on-line recycler.
Test times were from 200 to 1500 hours of oil ageing and
some of the tests showed that the oil quality was still
good after 4 times the normal oil life. The results showed
that the on line oil recycler cleaning system reduced the
rate of fall of the TBN and rate of increase of the TAN.
There was a very significant reduction in the soot in oil
and the fuel dilution. There was also a consistent reduction
in all the wear metals apart from copper and a
decrease in the rate of reduction of oil additives. There
was also measured on the Ford IDI engine a 5% reduced
fuel consumption. Many of these effects were attributed
to an influence of the cleaner oil on reduced engine
deposits
A concept guide for the Sub-Saharan African Challenge Program (SSA CP)
Describes the concept of innovation platforms and how to create them, with a focus on the Sub Saharan Africa Challenge Programme
Modelling cell wall growth using a fibre-reinforced hyperelastic–viscoplastic constitutive law
AbstractA fibre-reinforced hyperelastic–viscoplastic model using a finite strain Finite Element (FE) analysis is presented to study the expansive growth of cell walls. Based on the connections between biological concepts and plasticity theory, e.g. wall-loosening and plastic yield, wall-stiffening and plastic hardening, the modelling of cell wall growth is established within a framework of anisotropic viscoplasticity aiming to represent the corresponding biology-controlled behaviour of a cell wall. In order to model in vivo growth, special attention is paid to the differences between a living cell and an isolated wall. The proposed hyperelastic–viscoplastic theory provides a unique framework to clarify the interplay between cellulose microfibrils and cell wall matrix and how this interplay regulates sustainable growth in a particular direction while maintaining the mechanical strength of the cell walls by new material deposition. Moreover, the effect of temperature is taken into account. A numerical scheme is suggested and FE case studies are presented and compared with experimental data
Lithostratigraphical subdivision of the Sherwood Sandstone Group (Triassic) of the north-eastern part of the Carlisle Basin, Cumbria, and adjacent parts of Dumfries and Galloway, UK.
This report presents a review of the history of the lithostratigraphical subdivision of the Triassic
Sherwood Sandstone Group of the north-eastern part of the Carlisle Basin, Cumbria, and
adjacent parts of Dumfries and Galloway, UK. Two formations, the St Bees Sandstone and
Kirklinton Sandstone, have been mapped in the past. However, previous workers have found
considerable difficulty in consistently identifying, defining and mapping the Kirklinton
Sandstone Formation. Moreover, previous accounts of the sandstones in the Carlisle area appear
to suggest that the succession there differs in several key aspects from its correlatives in other
parts of Cumbria and, in particular, the adjacent offshore area. As a result of a short period of
field work in the area, it is concluded that the principal lithological change is between mainly
fine-grained sandstones, that are generally or commonly micaceous and contain common or
numerous mudstone interbeds, in the lower and middle parts of the group, and fine- to coarsegrained
sandstones with rare or no mica and mudstone partings at the top of the group. This
change occurs within the Kirklinton Sandstone Formation as previously mapped, and it is
suggested that this unit is now invalid. Several options are considered as to how the group should
be subdivided and the nomenclature to be adopted. All options presently have some associated
problems, but the adoption of the same terminology as in the continuous offshore is suggested,
i.e. St Bees Sandstone Formation below (subdivided where possible into Rottington Sandstone
and Calder Sandstone Members) and Ormskirk Sandstone Formation above
Adding a Brane to the Brane-Anti-Brane Action in BSFT
We attempt to generalize the effective action for the D-brane-anti-D-brane
system obtained from boundary superstring field theory (BSFT) by adding an
extra D-brane to it to obtain a covariantized action for 2 D-branes and 1
anti-D-brane. We discuss the approximations made to obtain the effective action
in closed form. Among other properties, this effective action admits solitonic
solutions of codimension 2 (vortices) when one of the D-brane is far separated
from the brane-anti-brane pair.Comment: 23 pages, 2 figures, minor revision
Genetic Similarities Among Geographic Isolates of Lysiphlebus testaceipes (Hymenoptera: Aphidiidae) Differing in Cold Temperature Tolerances
Lysiphlebus testaceipes (Cresson) is a solitary endoparasitoid of aphids and is the primary parasitoid attacking cereal aphids in the Great Plains, especially Schizaphis graminum (Rondani). In a previous study, it was found that a Lincoln, NE, isolate of L. testaceipes had a much higher survivorship at cold temperatures than isolates from Stillwater, OK, and Corpus Christi, TX. This suggested that the Nebraska isolate was locally adapted to the northern environment and perhaps genetically divergent from southern populations. We tested for genetic differentiation of the above isolates by sequencing portions of the COI and 16S mtDNA genes. We also examined a Florida isolate reared from Toxoptera citricida (Kirkaldy) and L. fabarum Marshall as an outgroup. The Great Plains isolates (Nebraska, Oklahoma, and Texas) were homogeneous with 0% and 0Ð0.2% sequence divergence in the COI and 16S gene fragments, respectively. The Florida isolate differed from the Great Plains isolates in nucleotide sequence by 1.4% (COI) and 0.5Ð0.7% (16S). Phylogenetic analysis placed the Florida isolate of L. testaceipes basal to the Great Plains isolates with L. fabarum, suggesting a possible species complex within L. testaceipes
Simple Statistical Probabilistic Forecasts of the winter NAO
The variability of the North Atlantic Oscillation (NAO) is a key aspect of Northern Hemisphere atmospheric circulation and has a profound impact upon the weather of the surrounding landmasses. Recent success with dynamical forecasts predicting the winter NAO at lead times of a few months has the potential to deliver great socioeconomic impacts. Here, a linear regression model is found to provide skillful predictions of the winter NAO based on a limited number of statistical predictors. Identified predictors include El Niño, Arctic sea ice, Atlantic SSTs, and tropical rainfall. These statistical models can show significant skill when used to make out-of-sample forecasts, and the method is extended to produce probabilistic predictions of the winter NAO. The statistical hindcasts can achieve similar levels of skill to state-of-the-art dynamical forecast models, although out-of-sample predictions are less skillful, albeit over a small period. Forecasts over a longer out-of-sample period suggest there is true skill in the statistical models, comparable with that of dynamical forecasting models. They can be used both to help evaluate and to offer insight into the sources of predictability and limitations of dynamical models
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