Positive affect and the experience of meaning in life.

Six studies examined the role of positive affect (PA) in the experience of meaning in life (MIL). Study 1 showed strong relations between measures of mood, goal appraisals, and MIL. In multivariate analyses, PA was a stronger predictor of MIL than goal appraisals. In Study 2, the most consistent predictor of the experience of meaning in a day was the PA experienced that day. Later, global MIL was predicted by average daily PA, rather than average daily MIL. Study 3 demonstrated no prospective relations between measures of MIL and PA over 2 years. In Study 4, priming positive mood concepts enhanced MIL. In Study 5, manipulated positive mood enhanced ratings of MIL for those who were not given an attributional cue for their moods. In Study 6, PA was associated with a high level of distinction between meaningful and meaningless activities. Results indicate that positive moods may predispose individuals to feel that life is meaningful. In addition, positive moods may increase sensitivity to the meaning-relevance of a situation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of strain rate on stress-strain behavior of alloy 309 and 304L austenitic stainless steel

The effect of strain rate on stress-strain behavior of austenitic stainless steel 309 and 304L was investigated. Tensile tests were conducted at room temperature at strain rates ranging from 1.25×10⁻⁴s⁻¹ to 400 s⁻¹. The evolution of volume fraction martensite that formed during plastic deformation was measured with X-ray diffraction and characterized with light microscopy. Alloy 304L was found to transform readily with strain, with martensite nucleating on slip bands and at slip band intersections. Alloy 309 did not exhibit strain-induced transformation. Variations in ductility and strength with strain rate are explained in terms of the competition between hardening, from the martensitic transformation and a positive strain rate sensitivity, and softening due to deformational heating. Existing models used to predict the increase in volume fraction martensite with strain were examined and modified to fit the experimental data of this study as well as recent data for alloys 304 and 301LN obtained from the literature.     

Using shared representations to improve coordination and intent inference

In groupware, users must communicate about their intentions and aintain common knowledge via communication channels that are explicitly designed into the system. Depending upon the task, generic communication tools like chat or a shared whiteboard may not be sufficient to support effective coordination. We have previously reported on a methodology that helps the designer develop task specific communication tools, called coordinating representations, for groupware systems. Coordinating representations lend structure and persistence to coordinating information. We have shown that coordinating representations are readily adopted by a user population, reduce coordination errors, and improve performance in a domain task. As we show in this article, coordinating representations present a unique opportunity to acquire user information in collaborative, user-adapted systems. Because coordinating representations support the exchange of coordinating information, they offer a window onto task and coordination-specific knowledge that is shared by users. Because they add structure to communication, the information that passes through them can be easily exploited by adaptive technology. This approach provides a simple technique for acquiring user knowledge in collaborative, user-adapted systems. We document our application of this approach to an existing groupware system. Several empirical results are provided. First, we show how information that is made available by a coordinating representation can be used to infer user intentions. We also show how this information can be used to mine free text chat for intent information, and show that this information further enhances intent inference. Empirical data shows that an automatic plan generation component, which is driven by information from a coordinating representation, reduces coordination errors and cognitive effort for its users. Finally, our methodology is summarized, and we present a framework for comparing our approach to other strategies for user knowledge acquisition in adaptive systems.     

Vision-based Target Geo-location using a Fixed-wing Miniature Air Vehicle

This paper presents a method for determining the GPS location of a ground-based object when imaged from a fixed-wing miniature air vehicle (MAV). Using the pixel location of the target in an image, measurements of MAV position and attitude, and camera pose angles, the target is localized in world coordinates. The main contribution of this paper is to present four techniques for reducing the localization error. In particular, we discuss RLS filtering, bias estimation, flight path selection, and wind estimation. The localization method has been implemented and flight tested on BYU’s MAV testbed and experimental results are presented demonstrating the localization of a target to within 3 m of its known GPS location.     

Styryl-based compounds as potential in vivo imaging agents for beta-amyloid plaques

A group of styryl-based neutral compounds has been synthesized in this study for potential use as in vivo imaging agents for beta-amyloid plaques. Of 56 candidates, 14 compounds were found to label beta-amyloid plaques well on Alzheimer's disease (AD) human brain sections in vitro. The binding affinity to beta-amyloid fibrils was then determined by measuring the change in fluorescence intensity. Interestingly, we found that a class of quinaldine-styryl scaffold compounds displays specific binding to beta-amyloid fibrils. A representative compound, STB-8, was used in ex vivo and in vivo imaging experiments on an AD transgenic mouse model and demonstrated excellent blood-brain barrier (BBB) permeability and specific staining of the AD beta-amyloid plaques.     

Adsorption of natural organic matter onto carbonaceous surfaces: atomic force microscopy study

The microscopic structure of carbonaceous surfaces exposed to natural organic matter (NOM) under aqueous conditions has been explored using atomic force microscopy (AFM). Dismal Swamp Water was used as the NOM source, while highly ordered pyrolytic graphite (HOPG) served as a surrogate for the graphene sheets that characterize the surface of many carbonaceous materials in aquatic environments. Under acidic conditions, the HOPG surface was covered with a densely packed monolayer of NOM molecules. In some cases, aggregates of well-defined, individual NOM molecules were observed that exhibited a degree of registry with respect to the HOPG substrate. This suggests that adsorbate-substrate interactions play a role in moderating the structure of the adsorbate layer. As the pH increased, the concentration of adsorbed NOM decreased systematically because of increasingly repulsive interactions between adsorbates. Increasing the ionic strength produced a modest increase in the concentration of adsorbed NOM. Ca2+ ions exerted a more pronounced influence on both the surface coverage of adsorbed NOM molecules and the size of individual adsorbates because of the effects of intermolecular complexation. In contrast to the spherical structures observed by AFM under aqueous conditions, adsorbed NOM formed a mixture of "ringlike" assemblies and larger aggregates upon drying.     

Aptamer-conjugated nanoparticles for the collection and detection of multiple cancer cells

We have extended the use the aptamer-conjugated nanoparticles for the collection and detection of multiple cancer cells. The aptamers were selected using a cell-based SELEX strategy in our laboratory for cancer cells that, when utilized in this method, allow for the selective recognition of the cells from complex mixtures including fetal bovine serum samples. Aptamer-conjugated magnetic nanoparticles were used for the selective targeting cell extraction, and aptamer-conjugated fluorescent nanoparticles were employed for sensitive cellular detection. Employing both types of nanoparticles allows for selective and sensitive detection not possible by using the particles separately. Fluorescent nanoparticles amplify the signal intensity versus a single fluorophore label resulting in improved sensitivity. In addition, aptamer-conjugated magnetic nanoparticles allow for extraction and enrichment of target cells not possible with other separation methods. Fluorescent imaging and a microplate reader were used for cellular detection to demonstrate the wide applicability of this methodology for medical diagnostics and cell enrichment and separation.     

Implementation of electron-transfer dissociation on a hybrid linear ion trap-orbitrap mass spectrometer

We describe the adaptation of a hybrid quadrupole linear ion trap-orbitrap mass spectrometer to accommodate electron-transfer ion/ion reactions (ETD) for peptide and protein characterization. The method utilizes pulsed, dual electrospray ion sources and requires minimal instrument modification. Switching between cation and reagent anion injection schemes is automated and accomplished within a few hundred milliseconds. Ion/ion reactions are conducted within the linear ion trap, after which the c- and z-type product ions are passed to the orbitrap for high-resolution m/z analysis. With this arrangement, mass accuracies are typically measured to within 2 ppm at a resolving power of approximately 60 000. Using large peptides and intact proteins, we demonstrate such capabilities will accelerate our ability to interrogate high-mass species. To illustrate compatibility with automated data-dependent analysis and subsequent data processing, we couple the technique with an online chromatographic separation of a yeast whole-cell lysate followed by peptide identification using ProSight PC. Fairly long pulsing times and relatively low ET efficiency, as compared to conventional ETD instrumentation, are the main drawbacks of this approach. Still, our results suggest that the implementation of ETD on sensitive, high-resolution, and high-mass accuracy hybrid instrumentation, such as the orbitrap, will substantially propel the emergent fields of middle- and top-down proteomics.     

Occlusion-capable multiview volumetric three-dimensional display

Volumetric 3D displays are frequently purported to lack the ability to reconstruct scenes with viewer-position-dependent effects such as occlusion. To counter these claims, a swept-screen 198-view horizontal-parallax-only 3D display is reported here that is capable of viewer-position-dependent effects. A digital projector illuminates a rotating vertical diffuser with a series of multiperspective 768 x 768 pixel renderings of a 3D scene. Evidence of near-far object occlusion is reported. The aggregate virtual screen surface for a stationary observer is described, as are guidelines to construct a full-parallax system and the theoretical ability of the present system to project imagery outside of the volume swept by the screen.     

Cytosolic delivery of membrane-impermeable molecules in dendritic cells using pH-responsive core-shell nanoparticles

Polycations that absorb protons in response to the acidification of endosomes can theoretically disrupt these vesicles via the "proton sponge" effect. To exploit this mechanism, we created nanoparticles with a segregated core-shell structure for efficient, noncytotoxic intracellular drug delivery. Cross-linked polymer nanoparticles were synthesized with a pH-responsive core and hydrophilic charged shell designed to disrupt endosomes and mediate drug/cell binding, respectively. By sequestering the relatively hydrophobic pH-responsive core component within a more hydrophilic pH-insensitive shell, nontoxic delivery of small molecules and proteins to the cytosol was achieved in dendritic cells, a key cell type of interest in the context of vaccines and immunotherapy.