פרסומים

Contrary to a common picture of relationships in a market economy, people often express communal and membership-seeking impulses via consumption choices, purchasing goods and services because other people are doing so as well. Shared identities are maintained and created in this way. Solidarity goods are goods whose value increases as the number of people enjoying them increases. Exclusivity goods are goods whose value decreases as the number of people enjoying them increases. Distinctions can be drawn among diverse value functions, capturing diverse relationships between the value of goods and the value of shared or unshared consumption. Though markets spontaneously produce solidarity goods, individuals sometimes have difficulty in producing such goods on their own, or in coordinating on choosing them. Here law has a potential role. There are implications for trend setting, clubs, partnerships, national events, social cascades and compliance without enforcement.

The combination of charge separation induced by the formation of a single photorefractive screening soliton and an applied external bias field in a paraelectric is shown to lead to a family of useful electro-optic guiding patterns and properties. (C) 2000 Optical Society of America.

The solubilization of 5 hydrophilic water-sol. aroma compds. in self-aggregating triblock amphiphilic copolymers of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO), with similar percentages of PEO and different mol. wts., was studied. The 5 hydrophilic compds. (diacetyl, 2-methylpyrazine, pyrrole, furfural, guaiacol) were carefully selected to represent hydrophilic mols. with a similar mol. wt. and mol. vol., but with different abilities to interact with the micellar core of PPO moieties and with the PEO palisade side chains. The solubilized solute mole fraction increased and the aggregate-water partition coeffs. of the solutes decreased with increasing free solute concn. in the aq. phase. The partition coeffs. were smaller than those obtained for hydrophobic compds. and equil. was reached at lower solubilization values. Guaiacol was the least hydrophilic mol. and had the highest partition coeff. Diacetyl was the most water-sol. compd. and exhibited the smallest partition coeff. The data reveal that the higher mol. wt. polymers solubilized more solute than the low-mol.-wt. polymers. Moreover it is supposed that at low solute concns., guaiacol (contg. a hydroxyl electron acceptor group) penetrates the core of the micelle and displaces water while at more elevated concns. it seems to be solubilized in the micelle corona. Diacetyl, the most hydrophilic solute investigated (consisting of electron donor groups), prefers mainly the corona since its affinity for the polymeric core is very weak. The solubilization occurs in the palisade layer and the partition coeff. is independent of the free solute concn. Selective site (palisade vs. core) solubilization of hydrophilic compds. in polymeric micelles can be a powerful tool to protect sensitive materials from reactants present in the continuous water phase and to conduct surface-sensitive org. reactions. Furthermore, selective release properties of reactants and products can be designed. (c) 2000 Academic Press. [on SciFinder(R)]

A study was made of the characteristics of microemulsions composed of sucrose monostearate (SMS), medium-chain triglycerides (MCT), or R-(+)-limonene, alcs., and water. The systems are homogeneous, soft, and waxy solids at room temp. but liquefy and structure into homogeneous microemulsions when heated to \textgreater40 °C. The amt. of solubilized water is enhanced as a function of the alc./oil ratio and is inversely proportional to the alc. chain length. Over 60 wt% water can be solubilized in systems consisting of propanol/MCT/SMS at a wt. ratio of 3:1:4 (initial wt. ratio). These microemulsions are unique and differ from nonionic ethoxylated-based microemulsions in that their viscosity is very low and is reduced with increasing amts. of solubilized water. The elec. cond. increases only slightly as a function of the water content and does not show typical bicontinuous or percolated behavior. The water in the core of the microemulsion strongly binds to the headgroups of the surfactant. Only at \textgreater15 wt% solubilization of water was free or bulk water detected in the core of the microemulsions. Such unique behavior of the core water might have a possible application in systems requiring monitoring of enzymic (lipase) reactions carried out in the microemulsions as microreactors. [on SciFinder(R)]

The linguistic study of Egyptian, fully deciphered only about 150 years ago, is a young discipline: modern Egyptian linguistics, dating more or less from the work of Hans-Jakob Polotsky, is much younger still: no more than about half a century old. Coptic, the final stage of Egyptian, dead as a spoken language at some point after the XIIIth century AD, had been scientifically known in the West from around the XVIIth century. It is a curious and somehow sobering thought that Champollion le Jeune probably got the brainwave and forward push to the final decipherment of the hieroglyphic script by a wholly and deeply erroneous idea about diachronic word order correspondence. He believed (or took for granted) that Coptic f-sôtm “he is hearing” (roughly, “he + hear”) was the inversion of a ‘pan-Egyptian’ sdm.f (“hear-he”), which, he thought, had the same tense form, but which - we now know - is in fact a cluster of homographs, drastically differing, formally and functionally, in tense form and syntactical status from one phase of Egyptian to another and within one and the same phase. The idea was wholly misguided, yet the confidence it gave him, and his conviction that Coptic and Egyptian were two phases of the same language were not unjustified, and led him to eventual success. Today we have a reasonably good synchronic resolution - and, paradoxically, a sometimes seemingly sharper diachronic resolution - of nearly four millennia of uninterrupted evolution of a language (or rather an ensemble of dialects and language varieties), made visible to us in the written documentation of five or six distinct broad linguistic systems (in the sense of la langue as well as norme and usage). Roughly, with some arbitrariness and considerable overlapping, Old Egyptian (“OE”, 2800-2200 BC), Middle Egyptian (“ME”, 2200-1500 BC), Late Egyptian (or Neo-Egyptian) (“LE”, 1500-700 BC); Demotic, from the VIIth-VIIIth century BC to the Vth century AD, and finally Coptic, ‘Christian Egyptian’, written in customized graphemic systems based on the Greek graphemes and several Egyptian ones, from the IVth century AD on, until its death as a spoken language: Arabic entered Egypt in the VIIth century AD, but Coptic probably lingered on until the XVIIth century. (Incidentally, Coptic is formally differentiated as ‘Egypto-Coptic’ in the current International Linguistic Bibliography. Roughly since the Fifties, Coptic Studies have moved away from Egyptology, a separation unfortunate for both Egyptology and Coptic studies, which has all but wiped out Coptic linguistics as a discipline). Most phases, as we conveniently and simplistically delimit them (ignoring here the relationships, complicated in Egyptian, between language phase and script phase, as well as the religious-political implications of traditional archaizing use of earlier phases) have considerable overlapping or ‘mutual leaking’ with preceding ones, as well as transitory stages, and of course numerous diasystems of registers and other linguistic varieties which become clearer as detailed description progresses. Some phases extend up to a thousand years, which makes the need for a finer sub-periodization obvious (Junge 1985). Generally speaking, we witness the uninterrupted evolution of a language on one and the same terrain, in its first attestation cradled in a Neolithic culture, before the end of its life-span a para-classical language, part of a pious and totally Christian civilization: very little secular literature is attested in Coptic.

We demonstrate experimentally that, in a paraelectric, nonstationary boundary conditions can dynamically halt the intrinsic instability of quasi-steady-state photorefractive self-trapping, driving beam evolution into a stable oscillating two-soliton-state configuration. (C) 2000 Optical Society of America OCIS codes: 190.5330, 230.3090.

In the framework of a first-price private-value auction, we study the seller as a player in a game with the buyers in which he has private information about their realized valuations. We find that depending upon his information, set of signals, and commitment power, he may strategically transmit messages to buyers in order to increase his revenue. In an environment where the seller knows the rankings and lacks any commitment power, we find that the seller is unable to exploit his information. However, in an environment where the seller knows the realized valuations and can credibly annouce either the true rankings or the true values (or announce nothing at all) but cannot commit as to which of these truthful messages to announce, then it is indeed possible to increase his revenue. If the seller, in addition, can commit to the full signaling strategy, then his expected revenue will be even higher. We believe that this line of research is fruitful for both better understanding behavior in auctions and finding paths to higher seller revenue.

PURPOSE: The purpose of this study was to evaluate the in vitro inhibitory potency of various amide analogues and derivatives of valproic acid toward human microsomal epoxide hydrolase (mEH). METHODS: mEH inhibition was evaluated in human liver microsomes with 25 microM (S)-(+)-styrene oxide as the substrate. Inhibitory potency expressed as the median inhibitory concentration (IC50) was calculated from the formation rate of the enzymatic product, (S)-(+)-1-phenyl-1,2-ethanediol. RESULTS: Inhibitory potency was directly correlated with lipophilicity and became significant for amides with a minimum of eight carbon atoms. Branched eight-carbon amides were more potent inhibitors than their straight chain isomer, octanamide. N-substituted valproylamide analogues had reduced or abolished inhibition potency with the exception of valproyl hydroxamic acid being a potent inhibitor. Inhibition potency was not stereoselective in two cases of chiral valpromide isomers. Valproyl glycinamide, a new antiepileptic drug currently undergoing phase II clinical trials and its major metabolite valproyl glycine were weak mEH inhibitors. Acid isomers of valproic acid were not potent mEH inhibitors. CONCLUSIONS: The structural requirements for valproylamide analogues for potent in vitro mEH inhibition are: an unsubstituted amide moiety; two saturated alkyl side chains; a minimum of eight carbons in the molecule.

Thermal reactions of cysteine/furfural and cysteine/ribose mixts. were studied in model systems to gain more insight into the influence of structured fluids such as L2 microemulsions and cubic phases on the generation of aroma compds. Formation of 2-furfurylthiol from cysteine/furfural was particularly efficient in L2 microemulsions and cubic phases compared to aq. systems. The reaction led to the formation of two new sulfur compds., which were identified as 2-(2-furyl)thiazolidine and, tentatively, N-(2-mercaptovinyl)-2-(2-furyl)thiazolidine. Similarly, generation of 2-furfurylthiol and 2-methyl-3-furanthiol from cysteine/ribose mixts. was strongly enhanced in structured fluids. The cubic phase was shown to be even more efficient in flavor generation than the L2 microemulsion. It was denoted "cubic catalyst" or "cubic selective microreactor". The obtained results are interpreted in terms of a surface and curvature control of the reactions defined by the structural properties of the formed surfactant assocs. [on SciFinder(R)]

Subjective probabilities are probabilities people express for uncertain events or outcomes. They are generated, or judged, by two major heuristics: 1. When outcomes are unique (e.g., the guilt of some defendant) or set in the future (e.g., the winner of the next election), the approach is "theoretical". People pull together whatever they know, or believe, to be relevant, and judge the probabilities of the possible outcomes by the closeness of the match between them and whatever "prediction model" they have built in their heads. This heuristic is called representativeness. 2. When outcomes are grouped in categories or by features (e.g., the percent of convictions for a given charge, or the percent of elections won by incumbents), the approach is "empirical": Let's sample what's out there and count. If the sampling is done in one's head, and the probabilities judged by the number of examples that come to mind, or by the ease – real or anticipated – with which they come to mind, the heuristic is that of availability. These heuristics have distinct signatures. They lead to predictable and systematic biases, among them: the extension fallacy, the base-rate fallacy, sample size neglect, regression neglect, the unpacking effect, overconfidence, hindsight bias and more.

The promotion of small-scale tourism is intuitively perceived as a suitable form of economic development for rural areas. However, its impact is controversial and not always obvious. To examine these issues, this paper presents an empirical analysis of public support to small-scale tourism enterprises in rural areas in Israel. Using the tools of cost-effectiveness and cost–benefit analysis, public assistance for this type of activity is shown to be able to generate considerable returns. Methodological issues in this kind of analysis are also discussed and the policy implications arising with respect to the suitability of different forms of tourism activity in rural areas are presented.