BLOCKAGE OF AMYLOID INDUCTION BY COLCHICINE IN AN ANIMAL MODEL

Colchicine was found to have a strong inhibitory effect on amyloid induction in an animal model. When CBA/J mice were treated with colchicine concurrently with the amyloid induction regimen, the incidence of amyloidosis was, depending upon the dosage of colchicine, significantly decreased (0.005–0.010 mg colchicine per day) or completely blocked (more than 0.015 mg colchicine per day). The colchicine treatment was effective not only when colchicine was given for the entire course of the amyloid induction regimen but also when it was given only in the late pre-amyloid or the amyloid phase of the regimen or to the recipients after the transfer of amyloid. The data suggest the colchicine is effective in blocking amyloidogenesis at its final stage(s), while it may not affect significantly amyloid already deposited in the tissue

Free recall test experience potentiates strategy-driven effects of value on memory.

People tend to show better memory for information that is deemed valuable or important. By one mechanism, individuals selectively engage deeper, semantic encoding strategies for high value items (Cohen, Rissman, Suthana, Castel, & Knowlton, 2014). By another mechanism, information paired with value or reward is automatically strengthened in memory via dopaminergic projections from midbrain to hippocampus (Shohamy & Adcock, 2010). We hypothesized that the latter mechanism would primarily enhance recollection-based memory, while the former mechanism would strengthen both recollection and familiarity. We also hypothesized that providing interspersed tests during study is a key to encouraging selective engagement of strategies. To test these hypotheses, we presented participants with sets of words, and each word was associated with a high or low point value. In some experiments, free recall tests were given after each list. In all experiments, a recognition test was administered 5 minutes after the final word list. Process dissociation was accomplished via remember/know judgments at recognition, a recall test probing both item memory and memory for a contextual detail (word plurality), and a task dissociation combining a recognition test for plurality (intended to probe recollection) with a speeded item recognition test (to probe familiarity). When recall tests were administered after study lists, high value strengthened both recollection and familiarity. When memory was not tested after each study list, but rather only at the end, value increased recollection but not familiarity. These dual process dissociations suggest that interspersed recall tests guide learners' use of metacognitive control to selectively apply effective encoding strategies. (PsycINFO Database Recor

Alternative Approaches to Energy Modeling

The effects of government and private sector energy policies are varied and interrelated. Before implementing research and development programs, new technologies, environmental and price regulations, import quotas, and other energy-related policies, the consequences of these programs must be identified and quantified on a regional basis. To evaluate the regional impacts of energy policies, we need to consider production costs, transportation costs, and the location of reserves, as well as the demands for energy and nonenergy goods. Developing techniques for analyzing these factors was the objective of many previous research efforts. The strengths and weaknesses of the resulting models are discussed in this paper and areas for future research are outlined. Only those models that consider more than one fuel and sector (i.e., residential, utility, etc.) are reviewed

Multi-paradigm modeling of mode I&II dynamic fracture mechanisms in single crystal silicon

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.Includes bibliographical references (leaves 41-43).In addition to its semi-conducting properties, silicon has the ability to be manipulated with high precision at very small length- scales. This property makes it very useful in the design of Nano/Micro-Electromechanical Systems (N/MEMS) and similar technologies. The understanding of fracture of silicon is crucial for the engineering process and the development of robust devices. However, the mechanisms of fracture in silicon are complex and are still not fully understood. Several experimental studies of fracture have been reported, however, these often lack insight into atomistic mechanisms of fracture. Ab initio computational methods (e.g. based on Density Functional Theory) to study silicon that are able to provide a fundamental description of the complex fracture mechanisms remain an open challenge. In particular, the mechanisms that lead to brittle cleavage or to the transition to ductile behavior of silicon at higher temperatures remains an open question. Empirical molecular dynamics (MD) studies have proven successful in simulating silicon fracture, but are unreliable and most models could not be validated against experimental results. Here we propose to use MD modeling based on a novel first principles reactive force fields ReaxFF, which has shown to be an accurate model to describe fracture processes of silicon. Two numerical methods are used here to study fracture mechanisms in silicon: a multi-paradigm model employing reactive and non-reactive force fields, and a fully reactive model. The CMDF and GRASP are used for the simulation of brittle fracture mechanisms in mode I and mode II loading conditions, as well as simulations of the brittle-to-ductile transition (BDT). Our results indicate that CMDF is suitable for modeling silicon brittle fracture, but has limitations during the study of the mechanisms involved in the BDT. GRASP provides a suitable framework for BDT study, and the results in this study provide for the first time an observation of the BDT without the use of an empirical model. In this thesis we report, for the first time, the direct atomistic simulation of the BTD in silicon, revealing the microscopic atomistic mechanisms that explains this drastic change in the behavior of silicon.by Alan Cohen.S.B