Effect of pressure on the flow behavior of polybutene

The rheology of submicron thick polymer melt is examined under high normal pressure conditions by a recently developed photobleached‐fluorescence imaging velocimetry technique. In particular, the validity and limitation of Reynold equation solution, which suggests a linear through‐thickness velocity profile, is investigated. Polybutene (PB) is sheared between two surfaces in a point contact. The results presented in this work suggest the existence of a critical pressure below which the through‐thickness velocity profile is close to linear. At higher pressures however, the profile assumes a sigmoidal shape resembling partial plug flow. The departure of the sigmoidal profile from the linear profile increases with pressure, which is indicative of a second‐order phase/glass transition. The nature of the transition is confirmed independently by examining the pressure‐dependent dynamics of PB squeeze films. The critical pressure for flow profile transition varies with molecular weight, which is consistent with the pressure‐induced glass transition of polymer melt

Cities and Skills

This paper examines the productivity (and wage) gains from locating in dense, urban environments. We distinguish between three potential explanations of why firms are willing to pay urban workers more: (1) the urban wage premium is spurious and is the result of omitted ability measures, (2) the urban wage premium works because cities enhance productivity and (3) the urban wage premium is the result of faster skill accumulation in cities. Using a combination of standard regressions, individual fixed effects estimation (using migrants) and instrumental variables methods, we find that the urban wage premium does not represent omitted ability bias and it is only in part a level effect to productivity. The bulk of the urban wage premium accrues over time as a result of greater skill accumulation in cities.

Effects of Nonmaternal Child Care on Inequality in Cognitive Skills

As a result of changing welfare policies, large numbers of children of poor, uneducated mothersare likely to receive care from others as their mothers enter the workforce. How will this change affect inequality in cognitive skills among young children? One view suggests that inequality will expand because children from economically advantaged families have access to better child care, and families with well-educated parents are more likely to reinforce the cognitive benefits of care. Another view argues that inequality will diminish because even though child care may be unequal, it may be less unequal than the home environments that are supplanted by nonmaternal care. A third view suggests that because the effects of care are inconsistent, there will be little overall change in inequality. Analysis of the children of mothers in the National Longitudinal Survey of Youth provides tentative evidence in support of the first view, that nonmaternal care tends to magnify inequality. Although ordinary least squares regressions reveal no effects of child care, fixed-effects models that control for differences between families indicate that children of high-income, well-educated mothers benefit from center-based care, but children of low-income, poorly educated mothers suffer a cognitive disadvantage from attending day care centers. Home-based care, however, is not associated with cognitive performance. Results from nonparametric analyses are consistent with the findings from fixed-effects models. The key results rely mainly on a relatively small sample of about 700 children in 300 families that sent their children to different types of care, and they do not pertain to families with only one child, so caution is warranted in generalizing the findings.

Suppression of beta1,3galactosyltransferase beta3Gal-T5 in cancer cells reduces sialyl-Lewis a and enhances poly-N-acetyllactosamines and sialyl-Lewis x on O-glycans

We investigated the role of beta 3 Gal-T5, a member of the beta 1,3galactosyltransferase (beta 1,3Gal-T) family, in cancer-associated glycosylation, focusing on the expression of sialyl-Lewis a (sLea, the epitope of CA19.9 antigen), poly N-acetyllactosamines, and sialyl-Lewis x (sLex) antigen. A clone permanently expressing an antisense fragment of beta 3Gal-T5 was obtained from the human pancreas adenocarcinoma cell line BxPC3 and characterized. Both beta 1,3Gal-T activity and sLea expression are dramatically impaired in the clone. Analysis of the oligosaccharides synthesized in cells metabolically labelled with tritiated galactose shows that a relevant amount of radioactivity is associated to large O-glycans. Endo-beta-galactosidase mostly releases NeuAc alpha 2-3Gal beta 1-3[Fuc alpha 1-4]GlcNAc beta 1-3Gal and NeuAc alpha 2-3Gal beta 1-3GlcNAc beta 1-3Gal from such O-glycans of BxPC3 membranes, but GlcNAc beta 1-3Gal and type 2 chain oligosaccharides, including NeuAc alpha 2-3Gal beta 1-4[Fuc alpha 1-3]GlcNAc beta 1-3Gal, from those of the antisense clone. Furthermore, BxPC3 cells secrete sLea in the culture media but not sLex, while antisense clone secretes mostly sLex, and accumulation of both antigens is prevented by benzyl-alpha-GalNAc. These data indicate that beta 3Gal-T5 suppression turns synthesis of type 1 chain O-glycans to poly N-acetyllactosamine elongation and termination by sLex. In other cell lines and clones, beta 3Gal-T5 transcript, beta 1,3Gal-T activity, and sLea antigen are also correlated, but quantitatively the relative expression ratios are very different from cell type to cell type. We suggest that beta 3Gal-T5 plays a relevant role in gastrointestinal and pancreatic tissues counteracting the glycosylation pattern associated to malignancy, and is necessary for the synthesis and secretion of CA19.9 antigen, whose expression still depends on multiple interacting factors

Municipal Water Demand Study of Western Skane, Sweden - Background Analysis with Some Preliminary Results

Water resource systems have been an important part of resources and environment related research at IIASA since its inception. As demands for water increase relative to supply, the intensity and efficiency of water resources management must be developed further. This in turn requires an increase in the degree of detail and sophistication of the analysis, including economic, social and environmental evaluation of water resources development alternatives aided by application of mathematical modeling techniques, to generate inputs for planning, design, and operational decisions. During the year of 1978 it was decided that parallel to the continuation of demand studies, an attempt would be made to integrate the results of our studies on water demands with water supply considerations. This new task was named "Regional Water Management" (Task 1, Resources and Environment Area). One of the case studies in this Task, carried out in collaboration with the Swedish Environmental Protection Board and the University of Lund, is the region of Western Skane, Sweden. Although the Task emphasizes demand-resource integration, some analysis of the demand per se is necessary for better understanding of demand-generating factors. In this paper, background analysis concerning the municipal water demand characteristics of and the data base available for the region is presented with some preliminary results

The magazine´s journalistic construction Caras y Caretas in the repression of the "Semana Trágica" ("Tragic Week") in 1919

La revista Caras y Caretas, como publicación semanal de actualidad, estructuró un discurso acerca de los conflictos obreros durante la época radical (1916-1930), con las cuales ofreció su postura frente a las tensiones sociales y políticas de la época. En ese sentido, se indaga la construcción periodística de la publicación ante el reclamo de los sectores obreros en los hechos de la denominada Semana Trágica de 1919. La investigación toma para el análisis los aportes teórico-metodológicos de Roger Chartier, Miguel Rodrigo Alsina, Roberto Marafioti, Héctor Borrat, entre otros. Entre las conclusiones obtenidas, se demostró la posición del semanario como actor político de cara a los conflictos obreros y en el marco de las relaciones de dominio instituidas. Construyó un discurso que presentó realidades dicotómicas o pares antagónicos entre un “ellos” y un “nosotros”, los cuales además se diferenciaban por principios de superioridad e inferioridad y de la necesidad de asimilar o proscribir a quienes no encajaban en el orden establecido. A través de diversas estrategias discursivas, la revista legitimó prácticas represivas por parte de la policía, el Ejército y del sector parapolicial Liga Patriótica Argentina.The magazine Caras y Caretas, as a current weekly, lead a speech about the workers conflicts during the radical period (1916-1930), through which it offered it position against the social and political tensions of the epoch. In that sense, the publication ́s journalistic construction is inquired due to the workers sectors claims in what is known as “Semana Trágica” (“Tragic week”) in 1919. The research takes into account the theorical-methodological approaches for the analysis, as well as Roger Chartier, Miguel Rodrigo Alsina, Roberto Marafioti, Hector Borrat, among others. It was determined that journal position as a political actor face to the worker issues and with the power relations installed. It structured a speech that showed the dichotomous facts or antagonic pairs between “them” and “us”, who were also distinguised by superiority and inferiority principles and the need of setting aside to the ones that did not fit in the status quo. Through the different discursive strategies, the magazine legitimized repressive practices of the police, the Army and the parapolicial sector Liga Patriótica Argentina (Argentine Patriotic League)

An Interactive Procedure for Multiobjective Analysis of Water Resources Allocation

This paper reports on part of IIASA's research concerning regional water management planning, focusing on the Western Skane region in Southern Sweden. The IIASA studies are concerned with four issues of particular importance to water resources management, namely, conflict resolution, criteria of choice, uncertainty, and institutional arrangements. This paper is related primarily to the first two of these issues. An interactive procedure seeking the satisfactory nondominated solution of the multiobjective water resources allocation problem is discussed. It is based on the Powell method with penalty function for the solution of scalar optimization problem and on a constraint and weighting method, or actually a reference objective method, for the solution of the multiobjective optimization problem. Application of the procedure is illustrated by an example referring to the situation in the Kavlinge River system in the Western Skane, Sweden