830 research outputs found
Calibration of the Radiocarbon Time Scale for the Southern Hemisphere: AD 1850-950
No full textWe have conducted a series of radiocarbon measurements on decadal samples of dendrochronologically dated wood from both hemispheres, spanning 1000 years (McCormac et al. 1998; Hogg et al. this issue). Using the data presented in Hogg et al., we show that during the period AD 950-1850 the 14C offset between the hemispheres is not constant, but varies periodically (~130 yr periodicity) with amplitudes varying between 1 and 10‰ (i.e. 8-80 yr), with a consequent effect on the 14C calibration of material from the Southern Hemisphere. A large increase in the offset occurs between AD 1245 and 1355. In this paper, we present a Southern Hemisphere high-precision calibration data set (SHCal02) that comprises measurements from New Zealand, Chile, and South Africa. This data, and a new value of 41 ± 14 yr for correction of the IntCal98 data for the period outside the range given here, is proposed for use in calibrating Southern Hemisphere 14C dates
The vanishing author in computer-generated works: a critical analysis of recent Australian case law
No full textAbstract
The use of software is ubiquitous in the creation of many copyright works, yet the requirement in copyright law that every work have a human author who engages in independent intellectual effort means that its use may prevent copyright subsistence. Several recent Australian cases have refocused attention on authorship as an essential criterion of copyright subsistence, and these cases suggest that much computer-produced output may be authorless and thus lack copyright protection. This article, the first in a two-part series, analyses how each case deals with the question of authorship of computer-produced works and why the use of software diminishes copyright protection for a significant number of computer-generated works. The article critiques the application of conventional notions of human authorship developed in the pre-computer age to modern productions and suggests alternative approaches to authorship that satisfy both the major objectives of copyright policy and the need to adapt to the computer age. The article argues that, without a broader judicial approach to authorship of computer-generated works, Parliament must remedy the lacuna in protection for these ‘authorless’ works. Possible solutions for reform are suggested. In a forthcoming article, the author comprehensively examines those reform proposals
High-precision radiocarbon measurements of contemporaneous tree-ring wood from the British Isles and New Zealand: AD 1850-950.
No full textThe University of Waikato, Hamilton, New Zealand and The Queen's University of Belfast, Northern Ireland radiocarbon dating laboratories have undertaken a series of high-precision measurements on decadal samples of dendrochronologically dated oak (Quercus petraea) from Great Britain and cedar (Libocedrus bidwillii) and silver pine (Lagarostrobos colensoi) from New Zealand. The results show an average hemispheric offset over the 900 yr of measurement of 40±13 yr. This value is not constant but varies with a periodicity of about 130 yr. The Northern Hemisphere measurements confirm the validity of the Pearson et al. (1986) calibration dataset
ShCal04 Southern Hemisphere Calibration, 0–11.0 Cal Kyr BP
No full textRecent measurements on dendrochronologically-dated wood from the Southern Hemisphere have shown that there are differences between the structural form of the radiocarbon calibration curves from each hemisphere. Thus, it is desirable, when possible, to use calibration data obtained from secure dendrochronologically-dated wood from the corresponding hemisphere. In this paper, we outline the recent work and point the reader to the internationally recommended data set that should be used for future calibration of Southern Hemisphere 14C dates
Singular equivalence and the (Fg) condition
No full textAbstractWe show that singular equivalences of Morita type with level between finite-dimensional Gorenstein algebras over a field preserve the (Fg) condition
De functie van kraton FG als compatibilizer in blends van nylon-6 en polypropyleen
No full textHet afstudeerproject maakte deel uit van een bij KSLA lopend onderzoek naar de werking van blok-copolymeren als compatibilizer, met name de door SHELL vervaardigde SBS en SEBS blok-copolymeren. Het voorgestelde systeem om de experimenten in het kader van de afstudeeropdracht mee uit te voeren is nylon-6/polypropyleen met kraton FG als compatibilizer. Kraton FG is een met maleinezuuranhydride gefunctionaliseerd SEBS blok-copolymeer. Kraton FG is een goede compatibilizer voor blends van nylon-6 en polypropyleen. De grensvlakspanning werd verlaagd, waardoor een fijnere dispersie verkregen werd. De slagvastheid nam toe. Het is niet goed mogelijk om een verband te leggen tussen de verlaging van de grensvlakspanning en de verlaging van de deeltjesgrootte. In dit onderzoek werd de grensvlakspanning in een 'spinning drop' met behulp van enkele methoden bepaald. Bij SHELL is een methode ontwikkeld, die aanzienlijk lagere grensvlakspanningen leverde dan de andere methoden. De tijdsduur van een meting volgens deze methode is ook veel lager (1- 2 uur in plaats van 4-6 uur). De toename van de slagvastheid was het grootst in blends met 25% disperse fase (6.25% kraton FG). Dit was het maximum in de serie blends, die tijdens dit onderzoek getest werden. Om de verbetering van de slagvastheid ten gevolge van de aanwezigheid van kraton FG te begrijpen, moet ook naar de eigenschappen van de matrix fase gekeken worden. De hechting tussen beide fasen zal door de aanwezigheid van kraton FG niet verbeterd worden. Dit is ook niet nodig, daar 'shear yielding' het voornaamste 'toughening' mechanisme in nylon-6 is. Door de reactie tussen kraton FG en nylon-6 zal de viscositeit van de matrix-fase toenemen. Deze verhoging van de viscositeit zal van invloed zijn op het dispersieproces. Dit verschijnsel is nog niet goed bekend, daar het onderzoek naar compatibilizers vooral gericht is op het grensvlak tussen de matrix en disperse fase (grensvlakspanning, adhesie). Door de aanwezigheid van compatibilizers wordt coalescentie van de deeltjes tegengegaan. De verklaring, die hiervoor gegeven wordt, is kinetisch van aard. Het is goed mogelijk dat coalescentie van twee deeltjes thermodynamisch ongunstig is ten gevolge van de aanwezigheid van compatibilizers aan het grensvlak.Applied Science
A designer FG-Nup that reconstitutes the selective transport barrier of the nuclear pore complex
No full textNuclear Pore Complexes (NPCs) regulate bidirectional transport between the nucleus and the cytoplasm. Intrinsically disordered FG-Nups line the NPC lumen and form a selective barrier, where transport of most proteins is inhibited whereas specific transporter proteins freely pass. The mechanism underlying selective transport through the NPC is still debated. Here, we reconstitute the selective behaviour of the NPC bottom-up by introducing a rationally designed artificial FG-Nup that mimics natural Nups. Using QCM-D, we measure selective binding of the artificial FG-Nup brushes to the transport receptor Kap95 over cytosolic proteins such as BSA. Solid-state nanopores with the artificial FG-Nups lining their inner walls support fast translocation of Kap95 while blocking BSA, thus demonstrating selectivity. Coarse-grained molecular dynamics simulations highlight the formation of a selective meshwork with densities comparable to native NPCs. Our findings show that simple design rules can recapitulate the selective behaviour of native FG-Nups and demonstrate that no specific spacer sequence nor a spatial segregation of different FG-motif types are needed to create selective NPCs.</p
Analytical and FE Modeling of FG Beams Based on A Refined Shear Deformable Beam Theory for Static and Dynamic Analyses of FG BeamsWith Thermoelastic Coupling
No full textThe static and dynamic thermoelastic analyses of the beams made of functionally graded materials (FGMs) are presented in this paper. Based on the refined third-order shear deformation beam theory proposed by the senior author and the variational principle, the governing equations of FG beams are deduced. The influence of temperature on Young’s modulus and coefficients of thermal expansion is taken into account when FG beams are subjected to thermal loading. The resulting governing equations are a system of the eighth-order differential equations in terms of displacement variables, and the thermoelastic coupling is included in the equations. An accurate and reliable two-noded beam element is developed for the bending and free vibration analysis of FG beams by employing the refined thirdorder shear deformation beam theory and the quasi-conforming element technique. Several typical examples of FG beams are solved using the present FG beam element to show the effects of the material distribution and thermal loading on the defections, stresses and natural frequencies of FG beams. The accuracy of both the analytical solutions and numerical results given by the proposed models are validated against the results reported in the literature or the 2D finite element results solved by the authors. The results show that the present models are capable of yielding not only accurate displacements but also accurate stresses and higher-order frequencies of free vibration for the FG beams with thermoelastic coupling
Author response image 1. Author response
No full textNuclear pore complexes (NPCs) conduct massive transport mediated by shuttling nuclear transport receptors (NTRs), while keeping nuclear and cytoplasmic contents separated. The NPC barrier in Xenopus relies primarily on the intrinsically disordered FG domain of Nup98. We now observed that Nup98 FG domains of mammals, lancelets, insects, nematodes, fungi, plants, amoebas, ciliates, and excavates spontaneously and rapidly phase-separate from dilute (submicromolar) aqueous solutions into characteristic 'FG particles'. This required neither sophisticated experimental conditions nor auxiliary eukaryotic factors. Instead, it occurred already during FG domain expression in bacteria. All Nup98 FG phases rejected inert macromolecules and yet allowed far larger NTR cargo complexes to rapidly enter. They even recapitulated the observations that large cargo-domains counteract NPC passage of NTR.cargo complexes, while cargo shielding and increased NTR.cargo surface-ratios override this inhibition. Their exquisite NPC-typical sorting selectivity and strong intrinsic assembly propensity suggest that Nup98 FG phases can form in authentic NPCs and indeed account for the permeability properties of the pore
Algebraic dynamic multilevel method for fractured geothermal reservoir simulation
No full textA dynamic multilevel method for fully-coupled simulation of flow and heat transfer in heterogeneous and fractured geothermal reservoirs is presented (FG-ADM). The FG-ADM develops an advanced simulation method which maintains its efficiency when scaled up to field-scale applications, at the same time, it remains accurate in presence of complex fluid physics and heterogeneous rock properties. The embedded discrete fracture model is employed to accurately represent fractures without the necessity of unstructured complex grids. On the fine-scale system, FG-ADM introduces a multi-resolution nested dynamic grid, based on the dynamic time-dependent solution of the heat and mass transport equations. The fully-coupled implicit simulation strategy, in addition to the multilevel multiscale framework, makes FG-ADM to be stable and efficient in presence of strong flow-heat coupling terms. Furthermore, its finite-volume formulation preserves local conservation for both mass and heat fluxes. Multi-level local basis functions for pressure and temperature are introduced, in order to accurately represent the heterogeneous fractured rocks. These basis functions are constructed at the beginning of the simulation, and are reused during the entire dynamic time-dependent simulation. For several heterogeneous test cases with complex fracture networks we show that, by employing only a fraction of the fine-scale grid cells, FG-ADM can accurately represent the complex flow-heat solutions in the fractured subsurface formations.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Numerical AnalysisReservoir Engineerin
- …
