20,770 research outputs found
Age-dependent female responses to a male ejaculate signal alter demographic opportunities for selection
A central tenet of evolutionary explanations for ageing is that the strength of selection wanes with age. However, data on age-specific expression and benefits of sexually selected traits are lacking—particularly for traits subject to sexual conflict. We addressed this by using as a model the responses of Drosophila melanogaster females of different ages to receipt of sex peptide (SP), a seminal fluid protein transferred with sperm during mating. SP can mediate sexual conflict, benefitting males while causing fitness costs in females. Virgin and mated females of all ages showed significantly reduced receptivity in response to SP. However, only young virgin females also showed increased egg laying; hence, there was a narrow demographic window of maximal responses to SP. Males gained significant ‘per mating’ fitness benefits only when mating with young females. The pattern completely reversed in matings with older females, where SP transfer was costly. The overall benefits of SP transfer (hence opportunity for selection) therefore reversed with female age. The data reveal a new example of demographic variation in the strength of selection, with convergence and conflicts of interest between males and ageing females occurring over different facets of responses to a sexually antagonistic trait
Asymptotic analysis of a secondary bifurcation of the one-dimensional Ginzburg-Landau equations of superconductivity
The bifurcation of asymmetric superconducting solutions from the normal solution is considered for the one-dimensional Ginzburg--Landau equations by the methods of formal asymptotics. The behavior of the bifurcating branch depends on the parameters d, the size of the superconducting slab, and , the Ginzburg--Landau parameter. The secondary bifurcation in which the asymmetric solution branches reconnect with the symmetric solution branch is studied for values of for which it is close to the primary bifurcation from the normal state. These values of form a curve in the -plane, which is determined. At one point on this curve, called the quintuple point, the primary bifurcations switch from being subcritical to supercritical, requiring a separate analysis. The results answer some of the conjectures of [A. Aftalion and W. C. Troy, Phys. D, 132 (1999), pp. 214--232]
Sequence distribution studies of dichloroprotoanemonin-methyl methacrylate copolymers
Chloride elimination and ultraviolet bands in dichloroprotoanemonin/methyl methacrylate copolymer
Condor services for the Global Grid:interoperability between Condor and OGSA
In order for existing grid middleware to remain viable it is important to investigate their potentialfor integration with emerging grid standards and architectural schemes. The Open Grid ServicesArchitecture (OGSA), developed by the Globus Alliance and based on standard XML-based webservices technology, was the first attempt to identify the architectural components required tomigrate towards standardized global grid service delivery. This paper presents an investigation intothe integration of Condor, a widely adopted and sophisticated high-throughput computing softwarepackage, and OGSA; with the aim of bringing Condor in line with advances in Grid computing andprovide the Grid community with a mature suite of high-throughput computing job and resourcemanagement services. This report identifies mappings between elements of the OGSA and Condorinfrastructures, potential areas of conflict, and defines a set of complementary architectural optionsby which individual Condor services can be exposed as OGSA Grid services, in order to achieve aseamless integration of Condor resources in a standardized grid environment
Evidence for extended, obscured starbursts in submm galaxies
We compare high-resolution optical and radio imaging of 12 luminous submm
galaxies at z=2.2+/-0.2 observed with HST and the MERLIN and VLA at comparable
spatial resolution, 0.3" (2kpc). The radio emission traces the likely
far-infrared morphology of these dusty, luminous galaxies. In ~30% of the
sample the radio appears unresolved, suggesting that the emission is compact:
either an obscured AGN or nuclear starburst. However, in the majority, ~70%
(8/12), the radio emission is resolved by MERLIN/VLA on scales of ~1" (10 kpc).
For these galaxies the radio morphologies are broadly similar to their
restframe UV emission seen by HST. We discuss the probable mechanisms for the
extended emission and conclude that their luminous radio and submm emission
arises from a large, spatially-extended starburst. The median SFRs are
1700Mo/yr occuring within a ~40kpc^2 region, giving a star formation density of
45Mo/yr/kpc^2. Such vigorous and extended starbursts appear to be uniquely
associated with the submm population. A more detailed comparison of the
distribution of UV and radio emission shows that the broad similarities on
large scales are not carried through to smaller scales, where there is rarely a
one-to-one correspondance. We interpret this as resulting from highly
structured internal obscuration, suggesting that the vigorous activity is
producing wind-blown channels through the obscuration in these galaxies. If
correct this underlines the difficulty of using UV morphologies to understand
structural properties of this population and also may explain the surprising
frequency of Ly-alpha emission in their spectra. [Abridged]Comment: 7 pages, 3 figure
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