Down-link OFDRMA communications

Wireless Networks - Orthogonal frequency-division multiplexing with random multiple access (OFDRMA) is discussed for down-link communications, whereby a single base-station transmits information...     

Responses of practicing psychologists to a web site developed to promote empirically supported treatments.

Increased adoption of empirically supported treatments (ESTs) has been hindered in part by inadequate and inconvenient access to EST information and training. To improve diffusion of ESTs, the authors developed a Web application to provide practitioners with concise information by disorder on ESTs. The resulting site, therapyadvisor.com, was evaluated by 239 practicing psychologists to assess the usefulness of the site and explore possible interactions of EST attitudes on ratings of usefulness and impact. Two thirds of participants indicated using ESTs in practice, and limited time and resources were cited as primary barriers to EST adoption. The Web application was rated positively by most participants and was reported to increase awareness of and commitment to try ESTs among approximately 60% of participants. The results of this project support the feasibility of a Web application to increase diffusion and promote further adoption of ESTs. Technological and e-learning advances are promising directions for encouraging the adoption of ESTs specifically and evidence-based practice generally, particularly among busy practitioners who have inadequate time and resources for more traditional forms of dissemination and training. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dynamics of hydrated iron(II) cations in nafion polymer membranes

Mössbauer studies of Fe²⁺ in water-soaked nafion polymer membranes in the temperature range between 90 K and 250 K have been performed. Above a critical temperature (～ 180 K) the spectra exhibit both elastic narrow absorption lines and quasielastic broad lines. These spectra are typical of bounded diffusion phenomena observed by Mössbauer spectroscopy in macromolecular systems like haemoglobin, myoglobin and ferritin. Similar spectral shapes have been observed by quasielastic neutron scattering from water in nafion membranes. Within 50 K above the critical temperature the total Mössbauer absorption area decreases by an order of magnitude whereas the narrow absorption line decreases by two orders of magnitude. The results are interpreted in terms of bounded diffusive motion of the iron. Using a model based on overdamped harmonically bound Brownian motion, the essential parameters of the iron motion can be derived as a function of temperature. The iron motion most probably reflects the motion of a large Fe²⁺ complex, e.g. Fe(H₂O)²⁺₆, which is attached to the polymer side chains via the sulphonic group.     

Harnessing the Melting Peculiarities of Ultra‐High Molecular Weight Polyethylene Fibers for the Processing of Compacted Fiber Composites

Summary: Compacted fiber composites offer unique properties due to their lack of an extraneous matrix. The conditions of processing ultra‐high molecular weight polyethylene (UHMWPE) fibers were simulated in a heated pressure cell. In situ X‐ray diffraction measurements were used to follow the relevant transitions and the changes in the degree of crystallinity during melting and crystallization. The results strongly support the suggestion that the hexagonal crystal phase, in which the chain conformation is extremely mobile on the segmental level, constitutes the physical basis of compaction technologies for processing UHMWPE fibers into a single‐polymer composite. This report suggests that using a pseudo‐phase diagram outlining the occurrence of different phases during slow heating and the degree of crystallinity can provide valuable insight into the technological parameters relevant for optimal processing conditions.

Degree of crystallinity as a function of pressure and temperature in a region relevant to compaction processes.     

Distilled Collections from Textual Image Queries

We present a distillation algorithm which operates on a large, unstructured, and noisy collection of internet images returned from an online object query. We introduce the notion of a distilled set, which is a clean, coherent, and structured subset of inlier images. In addition, the object of interest is properly segmented out throughout the distilled set. Our approach is unsupervised, built on a novel clustering scheme, and solves the distillation and object segmentation problems simultaneously. In essence, instead of distilling the collection of images, we distill a collection of loosely cutout foreground “shapes”, which may or may not contain the queried object. Our key observation, which motivated our clustering scheme, is that outlier shapes are expected to be random in nature, whereas, inlier shapes, which do tightly enclose the object of interest, tend to be well supported by similar shapes captured in similar views. We analyze the commonalities among candidate foreground segments, without aiming to analyze their semantics, but simply by clustering similar shapes and considering only the most significant clusters representing non‐trivial shapes. We show that when tuned conservatively, our distillation algorithm is able to extract a near perfect subset of true inliers. Furthermore, we show that our technique scales well in the sense that the precision rate remains high, as the collection grows. We demonstrate the utility of our distillation results with a number of interesting graphics applications.     

Efficient Incorporation of Clickable Unnatural Amino Acids Enables Rapid and Biocompatible Labeling of Proteins in Vitro and in Bacteria

Site-specific incorporation of unnatural amino acids (uAAs) bearing a bioorthogonal group has enabled the attachment – typically at a single site or at a few sites per protein – of chemical groups at precise locations for protein and biomaterial labeling, conjugation, and functionalization. Herein, we report the evolution of chromosomal Methanocaldococcus jannaschii tyrosyl-tRNA synthetase (aaRS) for the alkyne-bearing uAA, 4-propargyloxy-l -phenylalanine (pPR), with ∼30-fold increased production of green fluorescent protein containing three instances of pPR compared with a previously described M. jannaschii-derived aaRS for pPR, when expressed from a single chromosomal copy. We show that when expressed from multicopy plasmids, the evolved aaRSs enable the production – using a genomically recoded Escherichia coli and the non-recoded BL21 E. coli strain – of elastin-like polypeptides (ELPs) containing multiple pPR residues in high yields. We further show that the multisite incorporation of pPR in ELPs facilitates the rapid, robust, and nontoxic fluorescent labeling of these proteins in bacteria. The evolved variants described in this work can be used to produce a variety of protein and biomaterial conjugates and to create efficient minimal tags for protein labeling.     

Structure of the Equilibrated Ni(111)‐YSZ(111) Solid–Solid Interface

Solid‐state dewetting of continuous Ni films deposited on the (111) surface of yttrium‐stabilized zirconia (YSZ) was used to produce equilibrated Ni particles, and the solid–solid interface structure was determined using aberration‐corrected transmission electron microscopy. The ~150 nm thick Ni films were annealed at 1350°C in Ar + H₂ (99.9999%) at a partial pressure of oxygen of 10^?20 atm for 6 h. Transmission electron microscopy of equilibrated particles, which was conducted to analyze the structure at the interface, revealed that despite the 31% lattice mismatch between Ni and YSZ, the interface is semicoherent and a two‐dimensional network of misfit dislocations was identified.     

Deformation Control During Thermal Treatment of Electrospun PbZr0.52Ti0.48O3 Nanofiber Mats

This paper focuses on the deformation origin of PbZr_0.52Ti_0.48O₃ (PZT) fiber mats obtained by electrospinning. The main cause of deformation of the green mats during heating was found to be a nonuniform relaxation of the stretched PVP polymer, due to nonuniform thermal decomposition of the Pb‐hexanoate in the fibers. This relaxation starts under 100°C, well below the polymer decomposition temperature. The shrinkage was found to accelerate above the polymer glass transition point, giving rise to an overall linear change of almost 50%. The “green” PZT mats were easily separated from the collector by first depositing a pure PVP sublayer on the collector. An optimal fabrication and slow multistep thermal treatment process that provides fiber mats with desired PZT phase and overcomes the nonuniform deformation is described.     

Fast GL(n)-Invariant Framework for Tensors Regularization

We propose a novel framework for regularization of symmetric positive-definite (SPD) tensors (e.g., diffusion tensors). This framework is based on a local differential geometric approach. The manifold of symmetric positive-definite (SPD) matrices, P _n , is parameterized via the Iwasawa coordinate system. In this framework distances on P _n are measured in terms of a natural GL(n)-invariant metric. Via the mathematical concept of fiber bundles, we describe the tensor-valued image as a section where the metric over the section is induced by the metric over P _n . Then, a functional over the sections accompanied by a suitable data fitting term is defined. The variation of this functional with respect to the Iwasawa coordinates leads to a set of \frac12n(n+1)\frac{1}{2}n(n+1) coupled equations of motion. By means of the gradient descent method, these equations of motion define a Beltrami flow over P _n . It turns out that the local coordinate approach via the Iwasawa coordinate system results in very simple numerics that leads to fast convergence of the algorithm. Regularization results as well as results of fibers tractography for DTI are presented.