163,402 research outputs found
Interaction between fatty acid and the elastin network
No full textThe aim of the present study was to investigate the interaction between salts of fatty acids (FAS) and elastin. Absorption of fatty acids in elastin may affect the elasticity of elastin-containing tissue. Such phenomena could, for instance, be of relevance for the understanding of the formation of atherosclerotic plaque in blood vessel walls.Chapter I gives a general introduction on the relevance of this study and an outline of the thesis. Furthermore, it contains information on the characteristics of both elastin and FAS.In chapter 2, experiments are discussed that give insight into the absorption mechanism. Elastin from bovine ligamentum nuchae was exposed to solutions of FAS having hydrocarbon chain lengths varying between 12 and 16 carbon atoms. The amount absorbed was determined gravimetrically. The uptake of FAS can be described by a second order mechanism, in which the absorption rate depends on the concentration of FAS in solution and the number of absorption sites in elastin, and in which the desorption depends on the number of occupied sites. Competitive absorption experiments showed that the absorption rate constant decreases with increasing chain length. The binding of FAS is reversible. Therefore it is allowed to calculate the standard Gibbs energy, Δ abs G 0 of the absorption process from the absorption isotherms. The affinity of the FAS for elastin is predominantly determined by hydrophobic interaction. The value for Δ abs G 0 per CH 2 group in the FAS is -0.8±0.2kJ/mol. This is much smaller than Δ abs G 0 for the transfer of CH 2 from an aqueous to a nonaqueous environment (-4kJ/mol). The difference may be explained by the fact that the FAS monomers that bind to elastin are released from micelles in solution. Although under the experimental condition of pH= 10 where the experiment have been carried out, the overall electric charge in elastin is negative, the contribution from the negatively charged head group of the FAS to Δ abs G 0 is attractive and equal to about - 3k.J/mol. This suggests electrostatic attraction between FAS with positively charged groups, such as the desmosine and isodesmosine cross-links in elastin.Binding of FAS is accompanied by co-absorption of salt (NaCl) and solvent in the elastin. The former results in an osmotic pressure between the elastin sample and the surrounding solution. This pressure increases as the salt concentration and/or the chain length of the FAS increases. The uptake of solution partly occurs to compensate for the electrostatic repulsion between the negatively charged groups of FAS in elastin. The swelling and, hence, the absorption of FAS is limited by the cross-linking of elastin. Due to the presence of OH- ions and absorbed FAS, degradation of elastin occurs, resulting in a decrease in cross-link density which, in turn promotes the uptake of more FAS. The rate of cross-link rupture is proportional to the osmotic pressure, both are larger for FAS with a longer chain. The inference is that the degradation of elastin is enhanced by the internal osmotic pressure.Elastin is a network of randomly coiled polypeptide chains displaying rubber-elastic proper-ties. In chapters 3, 4 and 5 the influence of FAS on the rubber elasticity is studied.In chapter 3, the change in elasticity modulus, which is the retractive force per unit cross-sectional area, is considered. The modulus depends on the number of cross- links per unit volume of elastin. Because of the degradation of elastin, caused by FAS uptake, the number of crosslinks and hence, the elasticity modulus decrease. The degradation rate increases with increasing chain length of the absorbed FAS. In addition, FAS may also change the rheological character of elastin. After a relatively long incubation time, depending on the water content and temperature, FAS may induce a change from a pure rubber-like into viscoelastic behaviour.The influence of FAS on the conformational distribution of the chains in the network is discussed in chapter 4. The end-to-end length of the polypeptide chains does not change significantly upon FAS absorption, provided that the samples retain their rubber-elastic character. In the case of viscoelastic behaviour, no inference about the conformational properties of the chains could be made. Furthermore, the dependency of the conformational distribution on the temperature is hardly affected by FAS absorption. These results imply that the rotational freedom of the polypeptide chain is not significantly affected. The inference is made that the FAS molecules do not bind directly to the polypeptide units in the main chain, but rather to the (hydrophobic) side groups. It is also possible that FAS molecules bind to the cross- links, either through hydrophobic interaction with the alkyl groups and/or through electrostatic interactions with the positively charged quaternary ammonium group of the desmosine or isodesmosine units.Upon lowering the temperature, the number of accessible conformations of the polypeptide chain decreases, which results in a rubberglass transition over a relatively narrow temperature range. The transition temperature (T g ) decreases with increasing water content in elastin. This can be explained by the reduction of intermolecular interactions and therefore by an increase of the rotational freedom at higher water content. As it was concluded that the rotational freedom of the polypeptide chains is not affected by absorption of FAS, no influence of FAS on T g is expected. In chapter 5, this expectation was confirmed. Binding of FAS does not directly influence the T g . However, since absorption of FAS causes swelling of the elastin network, and, therefore increases the uptake of water, binding of FAS indirectly causes a shift of T g towards lower values.The most important conclusion concerning the interaction between FAS and elastin is that the direct influence of FAS on the elastic properties is very small. However, since FAS absorption is attended by swelling of the network and degradation of elastin, FAS absorption changes the rubber-elastic properties indirectly. The influence of the FAS is larger for longer chain length
Inertie in keuzegedrag
No full textWeggebruikers gaan niet bepaald efficiënt om met de informatie die hun wordt aangereikt, zoveel heeft wetenschappelijk onderzoek naar het reizigersgedrag wel aangetoond. Wetenschappers spreken in dit verband van inertie – een zekere traagheid in het verwerken en gebruiken van nieuwe informatie. Voor zijn proefschrift The Dynamics of User Perception, Decision Making and Route Choice onderzocht Jaap Vreeswijk de achtergronden van inertie bij keuzegedrag. In deze bijdrage lichten Vreeswijk en zijn promotors Van Berkum en Van Arem de belangrijkste resultaten toe.Transport & PlanningCivil Engineering and Geoscience
[Report to Chief J. E. Curry, by an unknown author #1]
No full textReport to Chief J. E. Curry, by an unknown author. The report contains a list of officers who gave depositions to the United States Attorney
[Report to Chief J. E. Curry, by an unknown author #2]
No full textReport to Chief J. E. Curry, by an unknown author. The report contains a list of officers who gave depositions to the United States Attorney
Murder on the mountain: author talk with Peter J. Wosh
No full textAuthor talk by Peter J. Wosh on May 5th, 2022, on his book, "Murder on the Mountain: crime, passion, and punishment in gilded age New Jersey.
Mr. Melvin J. Collier, RWWL AUC, June 2011
No full textThis video is a conversation with Mr. Melvin J. Collier. Mr. Collier talks about his book, "From Mississippi to Africa: A Journey of Discovery". Daniel Le, AUC Woodruff Library, is the interviewer
A Tripartite Post-Recession Rebalancing
No full textIn this latest Advance & Rutgers Report, entitled “A Tripartite Post-Recession Rebalancing,” Dean James W. Hughes and Professor Joseph J. Seneca deliver an incisive assessment of the current market conditions and obstacles in the path of our economic recovery. They offer a statistical cautionary tale that the private and public sector need to hear and acknowledge in order for the economy to make continued progress.This report was published as Issue Paper Number 7, November 2011, in Advance & Rutgers Report
Evidence for the decay B0→J/ψω and measurement of the relative branching fractions of meson decays to J/ψη and J/ψη′
No full textFirst evidence of the B 0 → J / ψ ω decay is found and the B s 0 → J / ψ η and B s 0 → J / ψ η ′ decays are studied using a dataset corresponding to an integrated luminosity of 1.0 fb -1 collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV. The branching fractions of these decays are measured relative to that of the B 0 → J / ψ ρ 0 decay:frac(B (B 0 → J / ψ ω), B (B 0 → J / ψ ρ 0)) = 0.89 ± 0.19 (stat) - 0.13 + 0.07 (syst),frac(B (B s 0 → J / ψ η), B (B 0 → J / ψ ρ 0)) = 14.0 ± 1.2 (stat) - 1.5 + 1.1 (syst) - 1.0 + 1.1 (frac(f d, f s)),frac(B (B s 0 → J / ψ η ′), B (B 0 → J / ψ ρ 0)) = 12.7 ± 1.1 (stat) - 1.3 + 0.5 (syst) - 0.9 + 1.0 (frac(f d, f s)), where the last uncertainty is due to the knowledge of f d / f s, the ratio of b-quark hadronization factors that accounts for the different production rate of B 0 and B s 0 mesons. The ratio of the branching fractions of B s 0 → J / ψ η ′ and B s 0 → J / ψ η decays is measured to befrac(B (B s 0 → J / ψ η ′), B (B s 0 → J / ψ η)) = 0.90 ± 0.09 (stat) - 0.02 + 0.06 (syst)
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
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