Image Deblurring in the Presence of Impulsive Noise

Consider the problem of image deblurring in the presence of impulsive noise. Standard image deconvolution methods rely on the Gaussian noise model and do not perform well with impulsive noise. The main challenge is to deblur the image, recover its discontinuities and at the same time remove the impulse noise. Median-based approaches are inadequate, because at high noise levels they induce nonlinear distortion that hampers the deblurring process. Distinguishing outliers from edge elements is difficult in current gradient-based edge-preserving restoration methods. The suggested approach integrates and extends the robust statistics, line process (half quadratic) and anisotropic diffusion points of view. We present a unified variational approach to image deblurring and impulse noise removal. The objective functional consists of a fidelity term and a regularizer. Data fidelity is quantified using the robust modified L ¹ norm, and elements from the Mumford-Shah functional are used for regularization. We show that the Mumford-Shah regularizer can be viewed as an extended line process. It reflects spatial organization properties of the image edges, that do not appear in the common line process or anisotropic diffusion. This allows to distinguish outliers from edges and leads to superior experimental results.     

Differential effects of diesel exhaust particles on T cell differentiation and autoimmune disease

Background

Exposure to particulate matter (PM) has been associated with increased incidence and severity of autoimmune disease. Diesel PM is primarily composed of an elemental carbon core and adsorbed organic compounds such as polycyclic aromatic hydrocarbons (PAHs) and contributes up to 40% of atmospheric PM. The organic fraction (OF) of PM excludes all metals and inorganics and retains most organic compounds, such as PAHs. Both PM and OF increase inflammation in vitro and aggravate autoimmune disease in humans. PAHs are known aryl hydrocarbon receptor (AHR) ligands. The AHR modulates T cell differentiation and effector function in vitro and in experimental autoimmune encephalomyelitis (EAE), a murine model of autoimmune disease. This study aims to identify whether the total mass or active components of PM are responsible for activating pathways associated with exposure to PM and autoimmune disease. This study tests the hypothesis that active components present in diesel PM and their OF enhance effector T cell differentiation and aggravate autoimmune disease.

Results

Two different diesel samples, each characterized for their components, were tested for their effects on autoimmunity. Both diesel PM enhanced effector T cell differentiation in an AHR-dose-dependent manner and suppressed regulatory T cell differentiation in vitro. Both diesel PM aggravated EAE in vivo. Fractionated diesel OFs exhibited the same effects as PM in vitro, but unlike PM, only one diesel OF aggravated EAE. Additionally, both synthetic PAH mixtures that represent specific PAHs found in the two diesel PM samples enhanced Th17 differentiation, however one lost this effect after metabolism and only one required the AHR.

Conclusions

These findings suggest that active components of PM and not total mass are driving T cell responses in vitro, but in vivo the PM matrix and complex mixtures adsorbed to the particles, not just the OF, are contributing to the observed EAE effects. This implies that examining OF alone may not be sufficient in vivo. These data further suggest that bioavailability and metabolism of organics, especially PAHs, may have an important role in vivo.

     

Effects of repetition on associative recognition in young and older adults: Item and associative strengthening.

Young and older adults studied word pairs and later discriminated studied pairs from various types of foils including recombined word-pairs and foil pairs containing one or two previously unstudied words. We manipulated how many times a specific word pair was repeated (1 or 5) and how many different words were associated with a given word (1 or 5) to tease apart the effects of item familiarity from recollection of the association. Rather than making simple old/new judgments, subjects chose one of five responses: (a) Old-Old (original), (b) Old-Old (rearranged), (c) Old-New, (d) New-Old, (e) New-New. Veridical recollection was impaired in old age in all memory conditions. There was evidence for a higher rate of false recollection of rearranged pairs following exact repetition of study pairs in older but not younger adults. In contrast, older adults were not more susceptible to interference than young adults when one or both words of the pair had multiple competing associates. Older adults were just as able as young adults to use item familiarity to recognize which word of a foil was old. This pattern suggests that recollection problems in advanced age are because of a deficit in older adults' formation or retrieval of new associations in memory. A modeling simulation provided good fits to these data and offers a mechanistic explanation based on an age-related reduction of working memory. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Nanopatterned Polymer Brushes for Triggered Detachment of Anchorage‐Dependent Cells

Surfaces modified with thermoresponsive poly(N‐isopropylacrylamide) (PNIPAAm) support mild and efficient harvesting of anchorage‐dependent cells. To enable cellular detachment, however, the surfaces must exhibit a narrow range of PNIPAAm thicknesses. In this work, this limitation is circumvented by introducing nanopatterns to grafted PNIPAAm brushes, eliminating the critical thickness requirement for cell‐culturing applications. Nanopatterned PNIPAAm surfaces are prepared using a combination of interferometric lithography (IL) and surface‐initiated polymerization. Above the lower critical solution temperature (LCST) of PNIPAAm (～32 °C), these surfaces support the attachment and proliferation of mammalian cells (e.g., fibroblasts and endothelial cells). Below the LCST of PNIPAAm, cells readily detach from the nanopatterned PNIPAAm surfaces without influence from the period of nanopatterns, which vary between 157 ± 9 nm to 1021 ± 17 nm. Cells selectively attach and proliferate on PNIPAAm nanopatterns as compared to thick unpatterned PNIPAAm, which is further exploited to spatially direct cellular growth to generate cellular micropatterns. Nanopatterned PNIPAAm surfaces provide a unique solution to the critical thickness issue for cell harvesting and facilitate spatial control of cellular growth on surfaces.     

Computational and Biochemical Design of a Nanopore Cleavable by a Cancer‐Secreted Enzyme

Many proteinaceous macromolecules selectively transport substrates across lipid bilayers and effectively serve as gated nanopores. Here, we engineered cleavage‐site motifs for human matrix metalloprotease 7 (MMP‐7) into the extracellular and pore‐constricting loops of OprD, a bacterial substrate‐specific transmembrane channel. Concurrent removal of two extracellular loops allowed MMP‐7 to access and hydrolyze a cleavage‐site motif engineered within the pore's major constricting loop, in both membrane‐incorporated and detergent‐solubilized OprDs. Import of antibiotics by the engineered OprDs into living bacteria pointed to their proper folding and integration in biological membranes. Purified engineered OprDs were also found to be properly folded in detergent. Hence, this study demonstrates the design of nanopores with a constriction cleavable by tumor‐secreted enzymes (like MMP‐7) for their potential incorporation in lipid‐based nanoparticles to accelerate drug release at the tumor site.     

Comprehension of pronouns in young and older adults.

Explored, in 3 experiments, the issue of whether young (19–37 yrs old) and older (57–84 yrs old) adults differ in their use of pragmatic information in anaphor resolution. 64 Ss from each age group were required to select the antecedent for the pronoun he in sentence pairs such as "Henry spoke at a meeting while John drove to the beach. He brought along a surfboard." Results indicate that young and older Ss were equally influenced by contextual constraints in choosing pronoun referents when the sentence containing the pronoun followed immediately after the context-setting sentence. When extraneous material intervened, however, both age groups became less consistent in their pronoun choices, with older Ss being more affected. Evidence is presented that the failure to use pragmatic constraints in pronoun assignment resulted from inability to recall the relevant contextual information. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Horizontal ramping rate framework to quantify hydropeaking stranding risk for fish

Hydropeaking due to hydropower production can have negative impacts on aquatic fauna. One of the mechanisms for causing impacts on fish and aquatic macroinvertebrates is linked to the rapid dewatering of habitats, which can result in stranding or trapping. The magnitude of these impacts depends both on the characteristics of the flow variations and of the river morphology, as well as biological parameters (species, behavior, etc). When discharge is rapidly reduced, the risk of impacts on fishes (and notably the risk of fish stranding in dewatered zones along the riverbank) is frequently assessed by calculations of vertical ramping velocity among other methods. However, to assess fish stranding risks, the lateral ramping velocity calculated as a horizontal ramping rate (HRR) appears to be a more relevant indicator as it directly measures shoreline drawdown rates. HRR has the advantage of integrating river morphology, but it remains challenging to calculate HRRs in complex situations such as braided rivers. Using hydraulic simulations of the Durance, a gravel bed braided river, we have developed an innovative approach for HRR calculation. Considering two simulated flows, the algorithms for the calculations require partitioning the finite elements into wet and drying meshes. To recommend rates of lowering discharges during hydropeaking events, further studies are required to evaluate more precisely HRR limits for fish stranding regarding biotic and abiotic parameters: species, sizes, nychthemeral cycles, temperature, substrate, and so forth.     

Cell-Like Capsules with “Smart” Compartments

Eukaryotic cells have inner compartments (organelles), each with distinct properties and functions. One mimic of this architecture, based on biopolymers, is the multicompartment capsule (MCC). Here, MCCs in which the inner compartments are chemically unique and “smart,” i.e., responsive to distinct stimuli in an orthogonal manner are created. Specifically, one compartment alone is induced to degrade when the MCC is contacted with an enzyme while other compartments remain unaffected. Similarly, just one compartment gets degraded upon contact with reactive oxygen species generated from hydrogen peroxide (H₂O₂). And thirdly, one compartment alone is degraded by an external, physical stimulus, namely, by irradiating the MCC with ultraviolet (UV) light. All these specific responses are achieved without resorting to complicated chemistry to create the compartments: the multivalent cation used to crosslink the biopolymer alginate (Alg) is simply altered. Compartments of Alg crosslinked by Ca²⁺ are shown to be sensitive to enzymes (alginate lyases) but not to H₂O₂ or UV, whereas the reverse is the case with Alg/Fe³⁺ compartments. These results imply the ability to selectively burst open a compartment in an MCC “on-demand” (i.e., as and when needed) and using biologically relevant stimuli. The results are then extended to a sequential degradation, where compartments in an MCC are degraded one after another, leaving behind an empty MCC lumen. Collectively, this work advances the MCC as a platform that not only emulates key features of cellular architecture, but can also begin to capture rudimentary cell-like behaviors.