A Multinomial Model of Event-Based Prospective Memory.

Prospective memory is remembering to perform an action in the future. The authors introduce the 1st formal model of event-based prospective memory, namely, a multinomial model that includes 2 separate parameters related to prospective memory processes. The 1st measures preparatory attentional processes, and the 2nd measures retrospective memory processes. The model was validated in 4 experiments. Manipulations of instructions to place importance on either the prospective memory task or the background task (Experiments 1 and 2) and manipulations of distinctiveness of prospective memory targets (Experiment 2) had expected effects on model parameters, as did a manipulation of the difficulty of prospective memory target encoding (Experiments 3 and 4). An alternative model was also evaluated. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Context-dependent nature of destabilizing mutations on the stability of FKBP12

The context-dependent nature in which mutations affect protein stability was investigated using the FK506-binding protein, FKBP12. Thirty-four mutations were made at sites throughout the protein, including residues located in the hydrophobic core, the beta-sheet, and the solvent-exposed face of the alpha-helix. Urea-induced denaturation experiments were used to measure the change in stability of the mutants relative to that of the wild type (Delta DeltaGU-F). The results clearly show that the extent of destabilization, or stabilization, is highly context-dependent. Correlations were sought in order to link Delta DeltaGU-F to various structural parameters. The strongest correlation found was between Delta DeltaGU-F and N, the number of methyl(ene) groups within a 6 A radius of the group(s) deleted. For mutations of buried hydrophobic residues, a correlation coefficient of 0.73 (n = 16,where n is the number of points) was obtained. This increased to 0.81 (n = 24) on inclusion of mutations of partially buried hydrophobic residues. These data could be superimposed on data obtained for other proteins for which similarly detailed studies have been performed. Thus, the contribution to stability from hydrophobic side chains, independent of the extent to which a side chain is buried, can be estimated quantitatively using N. This correlation appears to be a general feature of all globular proteins. The effect on stability of mutating polar and charged residues in the alpha-helix and beta-sheet was also found to be highly context-dependent. Previous experimental and statistical studies have shown that specific side chains can stabilize the N-caps of alpha-helices in proteins. Substitutions of Ile56 to Thr and Asp at the N-cap of the alpha-helix of FKBP12, however, were found to be highly destabilizing. Thus, the intrinsic propensities of an amino acid for a particular element of secondary structure can easily be outweighed by tertiary packing factors. This study highlights the importance of packing density in determining the contribution of a residue to protein stability. This is the most important factor that should be taken into consideration in protein design.     

Adolescent pregnancy and parenthood: Recent evidence and future directions.

An overview of recent research on adolescent sexual activity, pregnancy, and parenthood is presented, with a focus on the dearth of knowledge concerning psychological precursors and consequences. Although the rate of teenage childbearing has decreased substantially this century, increasing rates of sexual activity, illegitimacy, and welfare receipt raise public concerns. New research is discussed that suggests that many negative outcomes previously ascribed to mothers' age are as much causes or correlates of teenage pregnancy as effects of it, although this claim is less substantiated regarding effects on children of teenage mothers. Literature on fathers and grandmothers is summarized, and suggestions are made for furthering this research. An overview is given of recent successes among intervention programs, and policy implications of the new federal welfare law are considered for teenage mothers and their children. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Free semiring-representations and nondeterminism

Semirings provide a simple abstract model of the syntax for a nondeterministic programming language. Each element of a semiring is a nondeterministic program segment, and the semiring operations (+ and ?) correspond to nondeterministic or and program composition. This is analogous to using an algebraic theory for the abstract syntax of a deterministic language. In the case of algebraic theories, an algebra provides the semantics, and free algebras (which always exist) are particularly important. For a semiring, semantics is provided by a representation as a system of relations. This paper examines the question of when free representations exist. Unlike free algebras, free representations do not always exist. It is shown that a semiring has free representations generated by arbitrary sets of variables iff it has a free representation generated by a single variable. Examples of semirings are given that do not have free representations. However, for an important class of semirings, free representations are always available. This class consists of semirings which arise when nondeterminism is freely added to a deterministic programming language.     

High-density sub-100-nm peptide-gold nanoparticle complexes improve vaccine presentation by dendritic cells in vitro

Nanocarriers have been explored to improve the delivery of tumor antigens to dendritic cells (DCs). Gold nanoparticles are attractive nanocarriers because they are inert, non-toxic, and can be readily endocytosed by DCs. Here, we designed novel gold-based nanovaccines (AuNVs) using a simple self-assembling bottom-up conjugation method to generate high-peptide density delivery and effective immune responses with limited toxicity. AuNVs were synthesized using a self-assembling conjugation method and optimized using DC-to-splenocyte interferon-γ enzyme-linked immunosorbent spot assays. The AuNV design has shown successful peptide conjugation with approximately 90% yield while remaining smaller than 80 nm in diameter. DCs uptake AuNVs with minimal toxicity and are able to process the vaccine peptides on the particles to stimulate cytotoxic T lymphocytes (CTLs). These high-peptide density AuNVs can stimulate CTLs better than free peptides and have great potential as carriers for various vaccine types.     

Size-controlled synthesis of monodispersed gold nanoparticles via carbon monoxide gas reduction

An in depth analysis of gold nanoparticle (AuNP) synthesis and size tuning, utilizing carbon monoxide (CO) gas as a reducing agent, is presented for the first time. The sizes of the AuNPs are tunable from ~4 to 100 nm by altering the concentration of HAuCl4 and inlet CO gas-injection flow rate. It is also found that speciation of aqueous HAuCl4, prior to reduction, influences the size, morphology, and properties of AuNPs when reduced with CO gas. Ensemble extinction spectra and TEM images provide clear evidence that CO reduction offers a high level of monodispersity with standard deviations as low as 3%. Upon synthesis, no excess reducing agent remains in solution eliminating the need for purification. The time necessary to synthesize AuNPs, using CO, is less than 2 min.     

Advances and opportunities at the interface between microbial bioenergy and nanotechnology

In this review, we highlight many recent developments in nanotechnology of critical relevance to microbial bioenergy synthesis. Nanoparticles, nanotubes, nanofibres, and nanoporous materials, are each being utilised in powerful ways as tools for feedstock processing, genetic engineering, and biofuel harvesting, as well as in bioelectrochemical systems. As materials and techniques continue to mature, nanomaterials will become a truly integral part of the bioenergy sector. Sustainable bioenergy production will ultimately be achieved through interdisciplinary efforts that continue to bridge the gap between these traditionally distinct fields of study.