The Effects of Polymer Molecular Weight on Colloidal Retention and the Bridging Mechanism

A review of retention is presented. Included are discussions concerning retention mechanisms, variables which affect retention, variables affected by retention and various retention aids. A detailed experimental procedures involving the use of the dynamic retention/drainage jar is included along with several modifications of the apparatus. The purpose of the experimental work was to study the effects of polymer molecular weight on retention and the bridging mechanism. Two cationic retention aids of low and high molecular weight along with two non-ionic bridging agent retention aids were employed. Various combinations of these chemicals were studied at different levels of addition and under different shear conditions. The results are discussed as they relate to maximum retention, maximum retention and level of addition, percent improvement at various levels of addition, shear and shear resistance. It was found that in most cases higher molecular weight retention aids give higher retention than lower molecular weight retention aids. High molecular weight polymers are more efficient than low molecular weight polymers at high shear but less effective than the low molecular weight bridging agent regardless of shear. Increasing molecular weight gives increased stability to retention reduction by shear. Bridging does occur and increases with increasing molecular weight, to a point. Molecular weight and charge are both important in bridge formation

Alien Registration- Bergeron, Joseph F. (Auburn, Androscoggin County)

https://digitalmaine.com/alien_docs/30873/thumbnail.jp

Alien Registration- Bergeron, Joseph N. (Auburn, Androscoggin County)

https://digitalmaine.com/alien_docs/30874/thumbnail.jp

The Impact of Rent Controls in Non-Walrasian Markets: An Agent-Based Modeling Approach

We use agent-based models to consider rent ceilings in non-Walrasian housing markets, where bargaining between landlord and tenant leads to exchange at a range of prices. In the non-Walrasian setting agents who would be extramarginal in the Walrasian setting frequently are successful in renting, and actually account for a significant share of the units rented. This has several implications. First, rent ceilings above the Walrasian equilibrium price (WEP) can affect the market outcome. Second, rent ceilings that reduce the number of units rented do not necessarily reduce total market surplus. Finally, the distributional impact of rent controls differs from the Walrasian setting.

The Resurrection of Jesus: A Clinical Review of Psychiatric Hypotheses for the Biblical Story of Easter

Jesus’ resurrection to bodily life after death by crucifixion is foundational to orthodox Christianity. The disciples had encounters with Jesus after his crucifixion which caused them to believe he had been bodily resurrected to life again. Psychiatric hypotheses have been proposed as naturalistic explanations for his disciples’ beliefs, which include hallucinations, conversion disorder, and bereavement experiences. Since they propose hallucinatory symptoms that suggest the presence of underlying medical pathology, clinical appraisal of these hypotheses for the disciples’ encounters with the resurrected Jesus is warranted. Psychiatric hypotheses for the disciples’ belief in Jesus’ resurrection are found to be inconsistent with current medical understanding and do not offer plausible explanations for the biblical story of Easter

Zero-sum thinking, the evolution of effort suppressing beliefs, and economic development

We study the evolution of belief systems that suppress productive effort. These include concerns about the envy of others, beliefs in the importance of luck for success, disdain for competitive effort, and traditional beliefs in witchcraft. We show that such demotivating beliefs can evolve when interactions are zero-sum in nature, i.e., gains for one individual tend to come at the expense of others. Within a population, our model predicts a divergence between material and subjective payoffs, with material welfare being hump-shaped and subjective well-being being decreasing in demotivating beliefs. Across societies, our model predicts a positive relationship between zero-sum thinking and demotivating beliefs and a negative relationship between zero-sum thinking (or demotivating beliefs) and both material welfare and subjective well-being. We test the model’s predictions using data from two samples in the Democratic Republic of Congo and from the World Values Survey. In the DRC, we find a positive relationship between zero-sum thinking and the presence of demotivating beliefs, such as concerns about envy and beliefs in witchcraft. Globally, zero-sum thinking is associated with skepticism about the importance of hard work for success, lower income, less educational attainment, less financial security, and lower life satisfaction. Comparing individuals in the same zero-sum environment, we observe the divergence between material outcomes and subjective well-being predicted by our model

Inconsistencies among European Union Pharmaceutical Regulator Safety Communications: A Cross-Country Comparison

The European Medicines Agency (EMA) and national regulators share the responsibility to communicate to healthcare providers postmarketing safety events but little is known about the consistency of this process. We aimed to compare public availability of safety-related communications and drug withdrawals from the EMA and European Union member countries for novel medicines. We performed a cross-sectional analysis using public Dear Healthcare Professional Communications (DHPCs) for all novel medicines authorized between 2001 and 2010 by the EMA and available for use in France, Netherlands, Spain, and the United Kingdom. Between 2001 and 2010, the EMA approved 185 novel medicines. DHPCs could not be ascertained for the EMA. Among the 4 national regulators, as of April 30, 2013, at least one safety DHPC or withdrawal occurred for 53 (28.6%) medicines, totaling 90 DHPCs and 5 withdrawals. Among these 53 medicines, all 4 national agencies issued at least one communication for 17 (32.1%), three of the four for 25 (47.2%), two of the four for 6 (11.3%), and one of the four for 5 (9.4%). Five drugs were reported to be withdrawn, three by all four countries, one by three and one by two. Among the 95 DHPCs and withdrawals, 20 (21.1%) were issued by all 4 national regulators, 37 (38.9%) by 3 of the 4, 22 (23.2%) by 2 of the 4, and 16 (16.8%) by one. Consistency of making publicly available all identified safety DHPC or withdrawal across regulator pairs varied from 33% to 73% agreement. Safety communications were not made publicly available by the EMA. Among the 4 European member countries with national regulators that make DHPCs publicly available since at least 2001, there were substantial inconsistencies in safety communications for novel medicines. The impact of those inconsistencies in terms of public health remains to be determined

Drinfel'd Doubles and Lusztig's Symmetries of Two-Parameter Quantum Groups

We find the defining structures of two-parameter quantum groups $U_{r,s}(\frak g)$ corresponding to the orthogonal and the symplectic Lie algebras, which are realized as Drinfel'd doubles. We further investigate the environment conditions upon which the Lusztig's symmetries exist between $(U_{r,s}(\frak g), )$ and its associated object $(U_{s^{-1}, r^{-1}}(\frak g), )$.Comment: 25 pages AMSTe