233 research outputs found
The Google Book search settlement: A law and economics analysis
Full text linkBeginning in December 2004 Google has pursued a new project to create a book search engine (Google Book Search). The project has released a storm of controversy around the globe. While the supporters of Google Book Search conceive the project as a first reasonable step towards unlimited access to knowledge in the information age, its opponents fear profound negative effects due to an erosion of copyright law. Our law and economics analysis of the Book Search Project suggests that – from a copyright perspective – the proposed settlement may be beneficial to right holders, consumers, and Google. For instance, it may provide a solution to the still unsolved dilemma of orphan works. From a competition policy perspective, we stress the important aspect that Google’s pricing algorithm for orphan and unclaimed works effectively replicates a competitive Nash-Bertrand market outcome under post-settlement, third-party oversight.Book Rights Registry; Competition Policy; Copyright; Fair Use; Google Book Search; Library Program; Orphan Works
Two distinct mechanisms of vesicle-to-micelle and micelle-to-vesicle transition are mediated by the packing parameter of phospholipid–detergent systems
Full text linkThe detergent solubilization and reformation of phospholipid vesicles was studied for various detergents. Two distinct mechanisms of vesicle-to-micelle and micelle-to-vesicle transition were observed by turbidimetry and cryo-electron microscopy. The first mechanism involves fast solubilization of phospholipids and occurs via open vesicular intermediates. The reverse process, micelle-to-vesicle transition, mimics the vesicle-to-micelle transition. In the second mechanism the solubilization is a slow process that proceeds via micelles that pinch off from closed vesicles. During vesicle reformation, the micelle-to-vesicle transition, a large number of densely packed multilamellar vesicles are formed. The route used, for solubilization and reformation, by a given detergent–phospholipid combination is critically dependent on the overall packing parameter of the detergent-saturated phospholipid membranes. By a change of the overall packing parameter the solubilization and or reformation mechanism could be changed. All five detergents tested fit within the proposed model. With two detergents the mechanism could be changed by changing the phospholipid composition or the medium conditions.
Energy transfer from a fluorescent hydrogel to a hosted fluorophore
No full textThe fluorescent properties of a new 1,3,5-cyclohexyltricarboxamide-based low-molecular-weight hydrogelator (1) derivatized with one hydrophobic fluorophore and two hydrophilic substituents have been investigated. Gels of I are composed of long, nonbranched fibers of uniform diameter, as shown by cryo-transmission electron microscopy (cryo-TEM). The aggregation of the naphthalene fluorophore moieties of the gelator molecules in the gel fibers favors the occurrence of a fast energy migration process that allows a very efficient sensitization of the fluorescence of a hosted fluorophore. Such processes have been investigated by the addition of propyldansylarnide (PDNS). at two different concentrations, to gels of 1. Around 30% of the total PDNS added to the gels was found to be incorporated in the gel fibers, as confirmed by deconvolution of the fluorescence spectrum. excited-state lifetime measurements, and steady-state and time-resolved fluorescence anisotropy measurements. Moreover. anisotropy measurements show that the fluorophore that is incorporated within the gel fibers is almost completely immobilized. indicating that the interactions of PDNS with the gelator moieties are very strong. This particular configuration of donor (1) and acceptor (PDNS) molecules leads to a very efficient antenna effect. where 50% of the absorbed photons are funneled through to the dansyl derivative when one PDNS molecule is incorporated in the gel fibers for every 100 gelator molecules. A 5-fold higher concentration of PDNS increases the percentage of funneled photons to 75%
The highly dynamic heterochromatin protein Swi6 mediates degradation of heterochromatic transcripts
Full text linkThe aim of my thesis was to investigate the mechanism of heterochromatin repression mediated by heterochromatin protein Swi6 in S. pombe.
Research over the years challenged the view of heterochromatin as a static and transcriptionally inert structure. Especially in fission yeast it has become clear that heterochromatin silencing requires not only the action of chromatin modifying factors, but also transcriptional activity and RNA degradation processes. Moreover, heterochromatin protein Swi6 was shown to be highly dynamic, unlike what was expected for a protein that is perceived as a major structural component of heterochromatin. Yet, the prevailing model of heterochromatin establishment and spreading is thought to occur by iterative HP1 binding to methylated H3K9 and recruitment of histone methylation activity.
Driven by recent findings in our lab that described a new role for Swi6 in repression and provided a possible explanation for its dynamic behavior, I set out to investigate the mechanism in vivo by studying Swi6 dynamics. Therefore, a major focus of my PhD was to establish a suitable, robust microscopy-based method that allowed me to follow rapid dynamics and produce reliable data. The work I have done challenged the role of Swi6 in heterochromatin maintenance and spreading, but coincides with a clear involvement in sustaining tight repression. While H3K9me levels remained high in the absence of Swi6 and even spread into neighboring regions, heterochromatic transcript levels increased. These observations revealed unanticipated functions for Swi6 and made us reconsider the mechanism of Swi6-mediated silencing. As previously proposed, Swi6 could function as a co-transcriptional checkpoint that mediates RNA degradation (Keller et al., 2012). In this model RNA binds to Swi6 and gets primed for destruction as it is handed over to the RNA decay machinery, involving Cid14 and the exosome or the RNAi machinery. The target specificity depends on the epigenetic make-up of the locus, meaning the recognition of H3K9me by the CD of Swi6, while RNA binding occurs in a sequence independent manner (Keller et al., 2012). Therefore, additional processes that confer specificity, like siRNAs, are needed to ensure correct targeting of H3K9me marks to trigger Swi6-mediated turnover of unwanted RNA transcripts and not of any other random region in the genome
Engineering novel topical foams using hydrofluroalkane emulsions stabilised with pluronic surfactants
No full textAesthetics are very important for topical products and as a consequence elegant vehicles such as sprays and foams are often preferred by patients. Pressurised systems are ideal to dose foams, however, as so little is known about the influence of formulation characteristics on foam properties, the rational design of these systems difficult. This study aimed to assess the capability of pluronic surfactants to stabilise topical pressurised hydrofluoroalkane (HFA) emulsions and attempted to define the formulation characteristics that had an impact upon foam properties. In situ phase diagrams and conductivity measurements were used to characterise the HFA emulsions. Cryo-scanning electron microscopy images, collapse time (C-t) and wetting time (W-t) were used to assess the foams post dosing, i.e. after removal of the HFA. The results indicated that foam stability was a direct function of HFA emulsion type; HFA-in-water (HIW) emulsions generated stable foams,they had 30-100 mu m bubble diameter with c.a. 40 bubbles in a 0.45 mm x 0.40 mm area; water-in-HFA (WIH) emulsions created quick-breaking foams they contained 20-200 mu m sized bubbles and had 20 bubbles in an area of 0.45 mm x 0.40 mm. Therefore, the rational design of pressurised topical foams can be achieved if the formulation is analysed in situ. (C) 2009 Elsevier B.V. All rights reserved
Sugar-based gemini surfactants with ph-dependent aggrega. All rights reserved.tion properties
No full textAmphiphilic molecules possess parts, which are distinctively lipophilic and hydrophilic. This ambivalence lies at the basis of the intriguing properties of these molecules, selected by nature as the building-blocks of architectures essential for life (i.e., biological membranes), and chosen by scientists for several applications in fields as diverse as food industry, cleaning technologies, agrochemicals, and bio-medicine [1]
Multi-state photoluminescent properties of an overcrowded alkene-based molecular motor in aggregates
Full text linkPhotoisomerization and photoluminescence are two distinct energy dissipation pathways in light-driven molecular motors. The photoisomerization properties of discrete molecular motors have been well established in solution, but their photoluminescent properties have been rarely reported—especially in aggregates. Here, it is shown that an overcrowded alkene-based molecular motor exhibits distinct dynamic properties in solution and aggregate states, for example, gel and solid states. Despite the poor emissive properties of molecular motors in solution, a bright emission is observed in the aggregate states, including in gel and the crystalline solid. The emission wavelength is highly dependent on the nature of the supramolecular packing and order in the aggregates. As a result, the fluorescent color can be readily tuned reversibly via mechanical grinding and vapor fuming, which provides a new platform for developing multi-stimuli functional materials
The effect of hydrophilic and hydrophobic block length on the rheology of amphiphilic diblock Polystyrene-b-Poly(sodium methacrylate) copolymers prepared by ATRP
No full textFollowing our previous investigation on the effect of molecular architecture on the rheology of Polystyrene-b-Poly(sodium methacrylate) copolymers (PS-b-PMAA), we consider here diblock PS-b-PMAA copolymers characterized by a different length of either the hydrophilic or the hydrophobic block. Various copolymers characterized by different PS or PMAA block length have been prepared by ATRP (kinetics is also discussed) and studied from the point of view of their theological behaviour in water. To the best of our knowledge, this is the first systematic investigation concerning the effect of block length on the rheology of diblock polyelectrolytes. We found that the hydrophobic block length has small influence on the rheology. Surprisingly, the polymers with shortest PMAA blocks yield the strongest gels at high concentration. A simple model based on the classical theories of self-assembly and percolation of amphiphilic polymers has been here developed in order to explain the observed data. (C) 2014 Elsevier Inc. All rights reserved
Phase Behavior of Laundry Surfactants in Polar Solvents
Full text linkLaundry surfactants are usually mixtures of ionic and nonionic detergents that exhibit a complex phase behavior. Here the ternary phase behavior of an isotropic and a liquid crystalline (LC) surfactant mixture has been examined in water/solvent systems. The size of the LC area in the ternary phase diagram was correlated to solvent parameters including the dielectric constant and the Gordon cohesiveness parameter. The Gordon parameter was found to have a linear relationship with the amount of solvent needed to go from an LC to an isotropic state over a wide range of solvents from polar to apolar. For solvents in which no surfactant aggregation (micellar or inverted micellar) is expected, the size of the LC area is linear with the reciprocal of the dielectric constant of the solvent. On diluting practical detergent liquids with water, a large LC area can be avoided by using solvents with a relatively low dielectric constant and with a relatively low molecular weight.
The aggregated state of the surfactant mixtures in the isotropic regions of the phase diagram was studied using the solvatochromic fluorescent probe Nile Red. In the water corner of the phase diagram, the surfactants are aggregated into micelles. In strongly polar solvents, such as glycerol, ethylene glycol, formamide, and ethanolamine, the surfactants are also aggregated into micelles. In somewhat less polar solvents, such as methanol, ethanol, and t-butanol, the surfactant molecules are randomly distributed. In the surfactant-rich corner of the phase diagram of the isotropic mixture, the surfactant forms inverted micelles. An inverted micelle–to–micelle transition could be observed on dilution in ethylene glycol as a discontinuity in the trend of the Nile Red fluorescence maxima.
Managing pollution control in Brazil : the potential use of taxes and fines by federal and state governments
Full text linkThe authors make a case for federal monitoring of state environmental agencies'(SEPAs') performance because of the tradeoff for the states between the need to raise revenue from taxes on local output and the need to limit pollution. They also show that fines and taxes assigned respectively to the federal and state governments can improve firms'compliance and SEPA's performance, and hence environmental quality, without damaging state revenue, and perhaps even improving it. For their analysis, the authors rely on numerical policy simulations based on an analytical framework designed as a multilevel Stackelberg game. This framework reproduces the hierarchical structure of pollution control policies in Brazil, where the federal environmental protection agency relies on SEPAs to ensure that federally defined minimum ambient standards are met locally. The numerical simulations are based on a case study of the food, and the printing and publishing industries.Urban Services to the Poor,Environmental Economics&Policies,Water and Industry,Pollution Management&Control,Health Monitoring&Evaluation
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