Development and Validation of a Flowsheet Simulation Model for Neptunium Extraction in an Advanced PUREX Process

An Advanced PUREX process has been developed for separation and recycling of neptunium from spent nuclear fuel. This work presents a new flowsheet simulation model for the extraction of neptunium using centrifugal contactors, where mass transfer is modeled using two-film theory and a linear driving force. Distribution coefficients and neptunium redox reactions are modeled using published models. Mass transfer between the organic and aqueous phases in the phase separation zone is shown to have a negligible effect. The model is applied to a previously tested flowsheet and its predictions are shown to be in good agreement with the experimental results.     

Family of G protein {alpha} chains: amphipathic analysis and predicted structure of functional domains

The G proteins transduce hormonal and other signals into regulationof enzymes such as adenylyl cyclase and retinal cGMP phosphodiesterase.Each G protein contains an subunit that binds and hydrolyzesguanine nucleotides and interacts with ß subunitsand specific receptor and effector proteins. Amphipathic andsecondary structure analysis of the primary sequences of fivedifferent chains (bovine _s, _t1 and _t2, mouse _i, and rat _o)predicted the secondary structure of a composite chain (_avg).The chains contain four short regions of sequence homologousto regions in the GDP binding domain of bacterial elongationfactor Tu (EF-Tu). Similarities between the predicted secondarystructures of these regions in _avg and the known secondary structureof EF-Tu allowed us to construct a three-dimensional model ofthe GDP binding domain of _avg. Identification of the GDP bindingdomain of _avg defined three additional domains in the compositepolypeptide. The first includes the amino terminal 41 residuesof _avg, with a predicted am phipathic helical structure; thisdomain may control binding of the chains to the ßcomplex. The second domain, containing predicted ßstrands and helices, several of which are strongly amphipathic,probably contains sequences responsible for interaction of chains with effector enzymes. The predicted structure of thethird domain, containing the carhoxy terminal 100 amino acids,is predominantly ß sheet with an amphipathic helixat the carboxy terminus. We propose that this domain is reponsiblefor receptor binding. Our model should help direct further experimentsinto the structure and function of the G protein chain.     

Rosuvastatin Enhances the Catabolism of LDL apoB‐100 in Subjects with Combined Hyperlipidemia in a Dose Dependent Manner

Dose‐associated effects of rosuvastatin on the metabolism of apolipoprotein (apo) B‐100 in triacylglycerol rich lipoprotein (TRL, d < 1.019 g/ml) and low density lipoprotein (LDL) and of apoA‐I in high density lipoprotein (HDL) were assessed in subjects with combined hyperlipidemia. Our primary hypothesis was that maximal dose rosuvastatin would decrease the apoB‐100 production rate (PR), as well as increase apoB‐100 fractional catabolic rate (FCR). Eight subjects received placebo, rosuvastatin 5 mg/day, and rosuvastatin 40 mg/day for 8 weeks each in sequential order. The kinetics of apoB‐100 in TRL and LDL and apoA‐I in HDL were determined at the end of each phase using stable isotope methodology, gas chromatography‐mass spectrometry, and multicompartmental modeling. Rosuvastatin at 5 and 40 mg/day decreased LDL cholesterol by 44 and 54 % (both P < 0.0001), triacylglycerol by 14 % (ns) and 35 % (P < 0.01), apoB by 30 and 36 % (both P < 0.0001), respectively, and had no significant effects on HDL cholesterol or apoA‐I levels. Significant decreases in plasma markers of cholesterol synthesis and increases in cholesterol absorption markers were observed. Rosuvastatin 5 and 40 mg/day increased TRL apoB‐100 FCR by 36 and 46 % (both ns) and LDL apoB‐100 by 63 and 102 % (both P < 0.05), respectively. HDL apoA‐I PR increased with low dose rosuvastatin (12 %, P < 0.05) but not with maximal dose rosuvastatin. Neither rosuvastatin dose altered apoB‐100 PR or HDL apoA‐I FCR. Our data indicate that maximal dose rosuvastatin treatment in subjects with combined hyperlipidemia resulted in significant increases in the catabolism of LDL apoB‐100, with no significant effects on apoB‐100 production or HDL apoA‐I kinetics.     

树叶房子

现代建筑不再只是规矩方正的盒子,它所呈现出的不仅是建筑自身的功能性,而且被更多的被赋予了表现性和象征性。整个建筑被一系列不规则形状的铜质屋顶笼罩。屋顶的设计既尊重了原始地貌又参考了周围植物的形状。叶子形状的屋顶都是重叠的板,由象征着弯曲树干的管状钢结构支撑,而屋面材料波纹状的褶皱也是参照了海洋的波浪为模板。舒展的"叶脉"支撑出一个双层空间,通透的三维曲面玻璃将它围合,这即是这个树叶房子的组成和特色所在。     

Decentralised decision making in heterogeneous teams using anonymous optimisation

This paper considers the scenario where multiple autonomous agents must cooperate in making decisions to minimise a continuous and differentiable team cost function. A distributed and asynchronous optimisation algorithm is presented which allows each agent to incrementally refine their decisions while intermittently communicating with the rest of the team. A convergence analysis provides quantitative requirements on the frequency agents must communicate that is prescribed by the structure of the decision problem. In general the solution method will require every agent to communicate to and have a model of every other agent in the team. To overcome this, a specific subset of systems, called Partially Separable, is defined. These systems only require each agent to have a combined summary of the rest of the team and allows each agent to communicate locally over an acyclic communication network, greatly increasing the scalability of the system.     

Theory of mind associations with other cognitive functions and brain imaging in normal aging.

The study investigated age-related differences in theory of mind and explored the relationship between this ability, other cognitive abilities, and structural brain measures. A cohort of 106 adults (ages 50–90 years) was recruited. Participants completed tests of theory of mind, verbal and performance intelligence, executive function, and information processing speed and underwent structural magnetic resonance imaging (measurement of whole brain volume, volume of white matter hyperintensities, and diffusion tensor imaging of white matter integrity). Theory of mind ability declined with increasing age, and the relationship between theory of mind and age was fully mediated by performance intelligence, executive function, and information processing speed and was partially mediated by verbal intelligence. Theory of mind performance correlated significantly with diffusion tensor imaging measures of white matter integrity but not with volume of white matter hyperintensities or whole-brain volume. Theory of mind age-related decline may not be independent of other cognitive functions; it may also be particularly susceptible to changes in white matter integrity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Milgram, stress research, and the Institutional Review Board.

Comments on a recent attempted replication of the Milgram studies (Burger, January 2009) (see record 2008-19206-001). Over the last 20 years when lecturing to undergraduates, the author found that the students consistently and vehemently denied that similar results would be obtained “today.” They would note how much more independent individuals are now, how authority is not valued to the same extent that it was in the past, and so forth. Of course in the 1960s experts said the same things. No one predicted what happened then, and he doubts that many would have predicted what Burger (2009) found now. The author's comments, with one exception, are directed toward broader issues of the research enterprise relevant to concerns touched off by Milgram and subsequent practices of institutional review boards (IRBs). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Presynaptic modulation of sensory neurons in the segmental ganglia of arthropods

The afferent terminals of arthropod sensory neurones receive abundant input synapses, usually closely intermingled with the sites of synaptic output. The majority of the input synapses use the neurotransmitter GABA, but in some afferents there is a significant glutamatergic or histaminergic component. GABA and histamine shunt afferent action potentials by increasing chloride conductance. Though glutamate can also have this effect in the arthropod central nervous system, its action on afferent terminals appears to be mediated by increases in potassium conductance or by the action of metabotropic receptors. The action of the presynaptic synapses on the afferents are many and varied. Even on the same afferent, they may have several distinct roles that can involve both tonic and phasic patterns of primary afferent depolarisation. Despite the ubiquity and importance of their effects however, the populations of neurones from which the presynaptic synapses are made, remain largely unidentified.     

Toughness in synthetic and biological multilayered systems

Toughness in hard biological tissues is associated with fibrous or lamellar structures that deflect or stop growing cracks. In some cases, such as nacreous shell, protein interlayers absorb much of the crack energy. In other tissues, such as tooth enamel, the toughness derives from the mineral microstructure, and the small amount of residual protein apparently has little effect. There have been a number of efforts to make tough synthetic materials using layered structures. In this work, freeform fabrication has been used to make layered structures with a view to introducing similar toughness into brittle materials. Results are presented for epoxy-glass composites with glass fabric interlayers, porous alumina back-filled with aluminium metal, and layered glass-ceramic/silver materials.