The Theory of Reasoned Action as Parallel Constraint Satisfaction: Towards a Dynamic Computational Model of Health Behavior

The reasoned action approach, although ubiquitous in health behavior theory (e.g., Theory of Reasoned Action/Planned Behavior), does not adequately address two key dynamical aspects of health behavior: learning and the effect of immediate social context (i.e., social influence). To remedy this, we put forth a computational implementation of the Theory of Reasoned Action (TRA) using artificial-neural networks. Our model re-conceptualized behavioral intention as arising from a dynamic constraint satisfaction mechanism among a set of beliefs. In two simulations, we show that constraint satisfaction can simultaneously incorporate the effects of past experience (via learning) with the effects of immediate social context to yield behavioral intention, i.e., intention is dynamically constructed from both an individual’s pre-existing belief structure and the beliefs of others in the individual’s social context. In a third simulation, we illustrate the predictive ability of the model with respect to empirically derived behavioral intention. As the first known computational model of health behavior, it represents a significant advance in theory towards understanding the dynamics of health behavior. Furthermore, our approach may inform the development of population-level agent-based models of health behavior that aim to incorporate psychological theory into models of population dynamics

Origin of broad polydispersion in functionalized dendrimers and its effects on cancer cell binding affinity

Nanoparticles with multiple ligands have been proposed for use in nanomedicine. The multiple targeting ligands on each nanoparticle can bind to several locations on a cell surface facilitating both drug targeting and uptake. Experiments show that the distribution of conjugated ligands is unexpectedly broad, and the desorption rate appears to depends exponentially upon the mean number of attached ligands. These two findings are explained with a model in which ligands conjugate to the nanoparticle with a positive cooperativity of $\approx 4kT$, and that nanoparticles bound to a surface by multiple bonds are permanently affixed. This drives new analysis of the data, which confirms that there is only one time constant for desorption, that of a nanoparticle bound to the surface by a single bond.Comment: 4 pages, with 6 figure

Nanoscale Morphology of Type I Collagen is Altered in the Brtl Mouse Model of Osteogenesis Imperfecta

Bone has a complex hierarchical structure that has evolved to serve structural and metabolic roles in the body. Due to the complexity of bone structure and the number of diseases which affect the ultrastructural constituents of bone, it is important to develop quantitative methods to assess bone nanoscale properties. Autosomal dominant Osteogenesis Imperfecta results predominantly from glycine substitutions (80%) and splice site mutations (20%) in the genes encoding the α1 or α2 chains of Type I collagen. Genotype-phenotype correlations using over 830 collagen mutations have revealed that lethal mutations are located in regions crucial for collagen-ligand binding in the matrix. However, few of these correlations have been extended to collagen structure in bone. Here, an atomic force microscopy-based approach was used to image and quantitatively analyze the Dperiodic spacing of Type I collagen fibrils in femora from heterozygous (Brtl/+) mice (α1(I)G349C), compared to wild type (WT) littermates. This disease system has a well-defined change in the col1α1 allele, leading to a well characterized alteration in collagen protein structure, which are directly related to altered Type I collagen nanoscale morphology, as measured by the Dperiodic spacing. In Brtl/+ bone, the D-periodic spacing shows significantly greater variability on average and along the length of the bone compared to WT, although the average spacing was unchanged. Brtl/+ bone also had a significant difference in the population distribution of collagen D-period spacings. These changes may be due to the mutant collagen structure, or to the heterogeneity of collagen monomers in the Brtl/+ matrix. These observations at the nanoscale level provide insight into the structural basis for changes present in bone composition, geometry and mechanical integrity in Brtl/+ bones. Further studies are necessary to link these morphological observations to nanoscale mechanical integrity

Resisting Arrest: Analysis of Different Prone Body Positions on Time to Stand and Engage

An isolated police officer executing an arrest can be placed in a dangerous situation should the detainee become non-compliant. Further research is needed to ascertain the position that a detainee can be placed in that takes the longest time for them to rise from the ground, as this can influence the officer’s reaction time to a life-threatening situation. PURPOSE: Determine differences between participants\u27 time from four prone positions to a standing athletic position which would then prepare the participant to engage or run from the officer, similar to what could be seen during an interaction between police and detainees. METHODS: Twenty-four college-aged participants were recruited for this study; 9 participants were female and 15 were male. The following prone positions were examined in one session: prone position with hands hidden under the chest (PHC); prone position with arms perpendicular to the torso and palms of the hand facing up (PPU); prone position with arms perpendicular to the torso, palms of the hand facing up, with ankles crossed on the ground (PPUAC); and prone position with arms perpendicular to the torso, palms of the hand facing up, with ankles crossed but elevated toward the lower back (PACKB). The order of these positions was randomized amongst participants. Participants were instructed to rise to an athletic stance from each of these positions as quickly as possible, which was recorded by a video camera. Time was calculated via a frame-by-frame analysis using motion analysis software from movement initiation in the prone position until participants were standing in the athletic position. A 2 (sex) x 4 (position) repeated measures ANOVA with Bonferroni post hoc calculated between-position differences. RESULTS: There was a significant interaction for position (p=.003) but not sex (p=.415). The PACKB position was significantly slower than the PHC and PPUAC positions (p≤0.045) and had the slowest time to reach a standing position (~2.041 s). CONCLUSION: Previous data has indicated the average time for an officer to draw their weapon is 1.5 s. In this study participants were able to rise from the four prone position variations to an athletic position in ~2 s or less. As reaction time could influence an officer’s safety, the PPUAC position seems to require to most time for a detainee to stand and engage an officer

Type I Collagen Exists as a Distribution of Nanoscale Morphologies in Teeth, Bones and Tendons

This study demonstrates that collagen, the most abundant protein in animals, exists as a distribution of nanoscale morphologies in teeth, bones, and tendons. This fundamental characteristic of Type I collagen has not previously been reported and provides a new understanding of the nanoscale architecture of this ubiquitous and important biological nanomaterial. Dentin, bone, and tendon tissue samples were chosen for their differences in cellular origin and function, as well as to compare mineralized tissues with a tissue that lacks mineral in a normal physiological setting. A distribution of morphologies was present in all three tissues, confirming that this characteristic is fundamental to Type I collagen regardless of the presence of mineral, cellular origin of the collagen (osteoblast versus odontoblast versus fibroblast), anatomical location, or mechanical function of the tissue

A Dual TLR Agonist Adjuvant Enhances the Immunogenicity and Protective Efficacy of the Tuberculosis Vaccine Antigen ID93

With over eight million cases of tuberculosis each year there is a pressing need for the development of new vaccines against Mycobacterium tuberculosis. Subunit vaccines consisting of recombinant proteins are an attractive vaccine approach due to their inherent safety compared to attenuated live vaccines and the uniformity of manufacture. Addition of properly formulated TLR agonist-containing adjuvants to recombinant protein vaccines enhances the antigen-specific CD4+ T cell response characterized by IFN-γ and TNF, both of which are critical for the control of TB. We have developed a clinical stage vaccine candidate consisting of a recombinant fusion protein ID93 adjuvanted with the TLR4 agonist GLA-SE. Here we examine whether ID93+GLA-SE can be improved by the addition of a second TLR agonist. Addition of CpG containing DNA to ID93+GLA-SE enhanced the magnitude of the multi-functional TH1 response against ID93 characterized by co-production of IFN-γ, TNF, and IL-2. Addition of CpG also improved the protective efficacy of ID93+GLA-SE. Finally we demonstrate that this adjuvant synergy between GLA and CpG is independent of TRIF signaling, whereas TRIF is necessary for the adjuvant activity of GLA-SE in the absence of CpG

Young stars and non-stellar emission in the aligned radio galaxy 3C 256

We present ground-based images of the z=1.824 radio galaxy 3C 256 in the standard BVRIJHK filters and an interference filter centered at 8800A, a Hubble Space Telescope image in a filter dominated by Ly-alpha emission (F336W), and spectra covering rest-frame wavelengths from Ly-alpha to [O III] 5007. Together with published polarimetry observations, we use these to decompose the overall spectral energy distribution into nebular continuum emission, scattered quasar light, and stellar emission. The nebular continuum and scattered light together comprise half (one third) of the V-band (K-band) light within a 4-arcsec aperture, and are responsible for the strong alignment between the optical/near-infrared light and the radio emission. The stellar emission is dominated by a population estimated to be 100-200 Myr old (assuming a Salpeter IMF), and formed in a short burst with a peak star formation rate of 1-4x10^3 Msun/yr. The total stellar mass is estimated to be no more than 2x10^{11} Msun, which is far less than other luminous radio galaxies at similar redshifts, and suggests that 3C 256 will undergo further star formation or mergers.Comment: 35 pages including 10 figures; to appear in Nov 10 Ap