89 research outputs found
Zinc is incorporated into cuticular "tools" after ecdysis: the time course of the zinc distribution in "tools" and whole bodies of an ant and a scorpion
No full textAn understanding of the developmental course of specialized accumulations in the cuticular "tools" of arthropods will give clues to the chemical form, function and biology of these accumulations as well as to their evolutionary history. Specimens from individuals representing a range of developmental stages were examined using MeV - Ion microscopy. We found that zinc, manganese, calcium and chlorine began to accumulate in the mandibular teeth of the ant Tapinoma sessile after pre-ecdysial tanning, and the zinc mostly after eclosion; peak measured zinc concentrations reached 16% of dry mass. Accumulations in the pedipalp teeth, tarsal claws, cheliceral teeth and sting (aculeus) of the scorpion Vaejovis spinigeris also began after pre-ecdysial tanning and more than 48 h after ecdysis of the second instars. Zinc may be deposited in the fully formed cuticle through a network of nanometer scale canals that we observed only in the metal bearing cuticle of both the ants and scorpions. In addition to the elemental analyses of cuticular "tools", quantitative distribution maps for whole ants were obtained. The zinc content of the mandibular teeth was a small fraction of, and independent of, the total body content of zinc. We did not find specialized storage sites that were depleted when zinc was incorporated into the mandibular teeth. The similarities in the time course of zinc, manganese and calcium deposition in the cuticular "tools" of the ant (a hexapod arthropod) and those of the scorpion (a chelicerate arthropod) contribute to the evidence suggesting that heavy metal - halogen fortification evolved before these groups diverged
Can Intellectual Property Rights form a part of the Salvors' Traditional Rights, and Can a Balance be achieved between them? The position of English, American and South African Salvors in the light of the recent decisions of the RMS Titanic cases in
No full textA review of Salvage Law as it existed before the discovery of the RMS Titanic wreck, and the subsequent disputes about """"ownership"""" of the wreck. The laws of several maritime nations relating to Intellectual Property is examined, including Law of Copyright, of Trademarks and of Trade Secrets are examined and suggestions are made regarding the way forward
Nonlinear interactions during early stages of boundary layer transition induced by free-stream turbulence
No full textThe experimental study of a disturbed flat plate boundary layer subjected to moderate free-stream turbulence (FST) is presented. All measurements were conducted in a flow region with zero intermittency. By means of bispectral analysis it was found that after initial linear growth of low-frequency streaks two distinct nonlinear processes arises in a boundary layer. The first one is represented by interactions between low frequencies in upper third of a boundary layer and in immediate vicinity of it and the second one is an interaction of streaks with high-frequency disturbances across whole layer. In present experimental setup the region of nonlinear development had taken length about two-thirds of the measurements domain. Inside boundary layer the critical r.m.s.-amplitude of disturbances needed to initiate nonlinear development was found to be about 2 per cent of free-stream velocity
Facility Management van de Universiteit van Suriname
No full textVoor de Universiteit van Suriname moest een informatiesysteem opgezet worden om de faciliteiten aldaar te beheren. Hiervoor is gekeken naar de huidige manier van werken en de beschikbare technologieën, waarna het systeem ontworpen en geïmplementeerd is. Hierbij is de nadruk gelegd op de onderhoudbaarheid en mogelijkheid tot verdere ontwikkeling van dit systeem.Software TechnologyElectrical Engineering, Mathematics and Computer Scienc
Methyl 6-amino-6-oxohexanoate
No full textThe title compound, C7H13NO3, adopts an approximately planar conformation. The torsion angles in the aliphatic chain between the carbonyl group C atoms range from 172.97 (14) to 179.38 (14)° and the r.m.s. deviation of all non-H atoms is 0.059 Å. The crystal packing is dominated by two strong N—H...O hydrogen bonds involving the amide groups and forming R22(8) rings and C(4) chains. Overall, a two-dimensional network parallel to (100) is formed. A weak intermolecular C—H...O interaction is also present
Some observed seasonal changes in extratropical general circulation: A study in terms of vorticity
No full textExtratropical eddy distributions in four months typical of the four seasons are treated in terms of temporal mean and temporal r.m.s. values of the geostrophic relative vorticity. The geographical distributions of these parameters at the 300 mb level show that the arithmetic mean fields are highly biased representatives of the extratropical eddy distributions. The zonal arithmetic means of these parameters are also presented. These show that the zonal-and-time mean relative vorticity is but a small fraction of the zonal mean of the temporal r.m.s. relative vorticity, K. The reasons for considering the r.m.s. values as the temporal normal values of vorticity in the extratropics are given in considerable detail. The parameter K is shown to be of considerable importance in locating the extratropical frontal jet streams (EFJ) in time-and-zonal average distributions. The study leads to an understanding of the seasonal migrations of the EFJ which have not been explored until now
On fibers and accessibility of groups acting on trees with inversions
No full textThroughout this paper the actions of groups on
graphs with inversions are allowed. An element g of a group G is
called inverter if there exists a tree X where G acts such that g
transfers an edge of X into its inverse. A group G is called accessible
if G is finitely generated and there exists a tree on which G acts
such that each edge group is finite, no vertex is stabilized by G, and
each vertex group has at most one end.
In this paper we show that if G is a group acting on a tree
X such that if for each vertex v of X, the vertex group Gv of v
acts on a tree Xv, the edge group Ge of each edge e of X is finite
and contains no inverter elements of the vertex group Gt(e) of the
terminal t(e) of e, then we obtain a new tree denoted Xe and is called
a fiber tree such that G acts on Xe. As an application, we show that
if G is a group acting on a tree X such that the edge group Ge for
each edge e of X is finite and contains no inverter elements of Gt(e),
the vertex Gv group of each vertex v of X is accessible, and the
quotient graph G /X for the action of G on X is finite, then G is
an accessible group.The author would like to thank the referee for his(her) help and suggestions to improve the first draft of this paper
On fibers and accessibility of groups acting on trees with inversions
No full textThroughout this paper the actions of groups on
graphs with inversions are allowed. An element g of a group G is
called inverter if there exists a tree X where G acts such that g
transfers an edge of X into its inverse. A group G is called accessible
if G is finitely generated and there exists a tree on which G acts
such that each edge group is finite, no vertex is stabilized by G, and
each vertex group has at most one end.
In this paper we show that if G is a group acting on a tree
X such that if for each vertex v of X, the vertex group Gv of v
acts on a tree Xv, the edge group Ge of each edge e of X is finite
and contains no inverter elements of the vertex group Gt(e) of the
terminal t(e) of e, then we obtain a new tree denoted Xe and is called
a fiber tree such that G acts on Xe. As an application, we show that
if G is a group acting on a tree X such that the edge group Ge for
each edge e of X is finite and contains no inverter elements of Gt(e),
the vertex Gv group of each vertex v of X is accessible, and the
quotient graph G /X for the action of G on X is finite, then G is
an accessible group.The author would like to thank the referee for his(her) help and suggestions to improve the first draft of this paper
On fibers and accessibility of groups acting on trees with inversions
No full textThroughout this paper the actions of groups on
graphs with inversions are allowed. An element g of a group G is
called inverter if there exists a tree X where G acts such that g
transfers an edge of X into its inverse. A group G is called accessible
if G is finitely generated and there exists a tree on which G acts
such that each edge group is finite, no vertex is stabilized by G, and
each vertex group has at most one end.
In this paper we show that if G is a group acting on a tree
X such that if for each vertex v of X, the vertex group Gv of v
acts on a tree Xv, the edge group Ge of each edge e of X is finite
and contains no inverter elements of the vertex group Gt(e) of the
terminal t(e) of e, then we obtain a new tree denoted Xe and is called
a fiber tree such that G acts on Xe. As an application, we show that
if G is a group acting on a tree X such that the edge group Ge for
each edge e of X is finite and contains no inverter elements of Gt(e),
the vertex Gv group of each vertex v of X is accessible, and the
quotient graph G /X for the action of G on X is finite, then G is
an accessible group.The author would like to thank the referee for his(her) help and suggestions to improve the first draft of this paper
Deformation of a linear viscoelastic compliant coating in a turbulent flow
No full textWe investigate the deformation of a linear viscoelastic compliant coating in a turbulent flow for a wide range of coating parameters. A one-way coupling model is proposed in which the turbulent surface stresses are expressed as a sum of streamwise-travelling waves with amplitudes determined from the stress spectra of the corresponding flow over a rigid wall. The analytically calculated coating deformation is analysed in terms of the root-mean-square (r.m.s.) surface displacement and the corresponding point frequency spectra. The present study systematically investigates the influence of five coating properties namely density, stiffness, thickness, viscoelasticity and compressibility. The surface displacements increase linearly with the fluid/solid density ratio. They are linearly proportional to the coating thickness for thin coatings, while they become independent of the thickness for thick coatings. Very soft coatings show resonant behaviour, but the displacement for stiffer coatings is proportional to the inverse of the shear modulus. The viscoelastic loss angle has only a significant influence when resonances occur in the coating response, while Poisson's ratio has a minor effect for most cases. The modelled surface displacement is qualitatively compared with recent measurements on the deformation of three different coatings in a turbulent boundary-layer flow. The model predicts the order of magnitude of the surface displacement, and it captures the increase of the coating displacement with the Reynolds number and the coating softness. Finally, we propose a scaling that collapses all the experimental data for the r.m.s. of the vertical surface displacement onto a single curve.Fluid MechanicsSupport Process and EnergyMulti Phase System
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