Molecular Dynamics Simulation of Ga Penetration along Grain Boundaries in Al: a Dislocation Climb Mechanism

Many systems where a liquid metal is in contact with a polycrystalline solid exhibit deep liquid grooves where the grain boundary meets the solid-liquid interface. For example, liquid Ga quickly penetrates deep into grain boundaries in Al, leading to intergranular fracture under very small stresses. We report on a series of molecular dynamics simulations of liquid Ga in contact with an Al bicrystal. We identify the mechanism for liquid metal embrittlement, develop a new model for it, and show that is in excellent agreement with both simulation and experimental data

Development of a protocol for maintaining viability while shipping organoid-derived retinal tissue.

Retinal organoid technology enables generation of an inexhaustible supply of three-dimensional retinal tissue from human pluripotent stem cells (hPSCs) for regenerative medicine applications. The high similarity of organoid-derived retinal tissue and transplantable human fetal retina provides an opportunity for evaluating and modeling retinal tissue replacement strategies in relevant animal models in the effort to develop a functional retinal patch to restore vision in patients with profound blindness caused by retinal degeneration. Because of the complexity of this very promising approach requiring specialized stem cell and grafting techniques, the tasks of retinal tissue derivation and transplantation are frequently split between geographically distant teams. Delivery of delicate and perishable neural tissue such as retina to the surgical sites requires a reliable shipping protocol and also controlled temperature conditions with damage-reporting mechanisms in place to prevent transplantation of tissue damaged in transit into expensive animal models. We have developed a robust overnight tissue shipping protocol providing reliable temperature control, live monitoring of the shipment conditions and physical location of the package, and damage reporting at the time of delivery. This allows for shipping of viable (transplantation-competent) hPSC-derived retinal tissue over large distances, thus enabling stem cell and surgical teams from different parts of the country to work together and maximize successful engraftment of organoid-derived retinal tissue. Although this protocol was developed for preclinical in vivo studies in animal models, it is potentially translatable for clinical transplantation in the future and will contribute to developing clinical protocols for restoring vision in patients with retinal degeneration

Converting genetic network oscillations into somite spatial pattern

In most vertebrate species, the body axis is generated by the formation of repeated transient structures called somites. This spatial periodicity in somitogenesis has been related to the temporally sustained oscillations in certain mRNAs and their associated gene products in the cells forming the presomatic mesoderm. The mechanism underlying these oscillations have been identified as due to the delays involved in the synthesis of mRNA and translation into protein molecules [J. Lewis, Current Biol. {\bf 13}, 1398 (2003)]. In addition, in the zebrafish embryo intercellular Notch signalling couples these oscillators and a longitudinal positional information signal in the form of an Fgf8 gradient exists that could be used to transform these coupled temporal oscillations into the observed spatial periodicity of somites. Here we consider a simple model based on this known biology and study its consequences for somitogenesis. Comparison is made with the known properties of somite formation in the zebrafish embryo . We also study the effects of localized Fgf8 perturbations on somite patterning.Comment: 7 pages, 7 figure

Aerobic fitness does not modulate protein metabolism in response to increased exercise: a controlled trial

© 2009 Smith et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

Efficient 5-OP-RU-induced enrichment of mucosa-associated invariant t cells in the murine lung does not enhance control of aerosol mycobacterium tuberculosis infection

Mucosa-associated invariant T (MAIT) cells are an innate-like T cell subset in mammals that recognize microbial vitamin B metabolites presented by the evolutionarily conserved major histocompatibility complex class I (MHC I)-related molecule, MR1. Emerging data suggest that MAIT cells may be an attractive target for vaccine-induced protection against bacterial infections because of their rapid cytotoxic responses at mucosal services to a widely conserved bacterial ligand. In this study, we tested whether a MAIT cell priming strategy could protect against aerosol Mycobacterium tuberculosis infection in mice. Intranasal costimulation with the lipopeptide Toll-like receptor (TLR)2/6 agonist, Pam2Cys (P2C), and the synthetic MR1 ligand, 5-OP-RU, resulted in robust expansion of MAIT cells in the lung. Although MAIT cell priming significantly enhanced MAIT cell activation and expansion early after M. tuberculosis challenge, these MAIT cells did not restrict M. tuberculosis bacterial load. MAIT cells were depleted by the onset of the adaptive immune response, with decreased detection of granzyme B+ and gamma interferon (IFN-γ)+ MAIT cells relative to that in uninfected P2C/5-OP-RU-treated mice. Decreasing the infectious inoculum, varying the time between priming and aerosol infection, and testing MAIT cell priming in nitric oxide synthase 2 (NOS2)-deficient mice all failed to reveal an effect of P2C/5-OP-RU-induced MAIT cells on M. tuberculosis control. We conclude that intranasal MAIT cell priming in mice induces early MAIT cell activation and expansion after M. tuberculosis exposure, without attenuating M. tuberculosis growth, suggesting that MAIT cell enrichment in the lung is not sufficient to control M. tuberculosis infection

Capacity of deep‐sea corals to obtain nutrition from cold seeps aligned with microbiome reorganization

Cold seeps in the deep sea harbor various animals that have adapted to utilize seepage chemicals with the aid of chemosynthetic microbes that serve as primary producers. Corals are among the animals that live near seep habitats and yet, there is a lack of evidence that corals gain benefits and/or incur costs from cold seeps. Here, we focused on Callogorgia delta and Paramuricea sp. type B3 that live near and far from visual signs of currently active seepage at five sites in the deep Gulf of Mexico. We tested whether these corals rely on chemosynthetically-derived food in seep habitats and how the proximity to cold seeps may influence; (i) coral colony traits (i.e., health status, growth rate, regrowth after sampling, and branch loss) and associated epifauna, (ii) associated microbiome, and (iii) host transcriptomes. Stable isotope data showed that many coral colonies utilized chemosynthetically derived food, but the feeding strategy differed by coral species. The microbiome composition of C. delta, unlike Paramuricea sp., varied significantly between seep and non-seep colonies and both coral species were associated with various sulfur-oxidizing bacteria (SUP05). Interestingly, the relative abundances of SUP05 varied among seep and non-seep colonies and were strongly correlated with carbon and nitrogen stable isotope values. In contrast, the proximity to cold seeps did not have a measurable effect on gene expression, colony traits, or associated epifauna in coral species. Our work provides the first evidence that some corals may gain benefits from living near cold seeps with apparently limited costs to the colonies. Cold seeps provide not only hard substrate but also food to cold-water corals. Furthermore, restructuring of the microbiome communities (particularly SUP05) is likely the key adaptive process to aid corals in utilizing seepage-derived carbon. This highlights that those deep-sea corals may upregulate particular microbial symbiont communities to cope with environmental gradients

Fusion versus Breakup: Observation of Large Fusion Suppression for ^9Be + ^{208}Pb

Complete fusion excitation functions for $^{9}$Be + $^{208}$Pb have been measured to high precision at near barrier energies. The experimental fusion barrier distribution extracted from these data allows reliable prediction of the expected complete fusion cross-sections. However, the measured cross-sections are only 68% of those predicted. The large cross-sections observed for incomplete fusion products support the interpretation that this suppression of fusion is caused by $^{9}$Be breaking up into charged fragments before reaching the fusion barrier. Implications for the fusion of radioactive nuclei are discussed.Comment: RevTex, 11 pages, 2 postscript figures, to appear in PR

Enhancement of the emission of mineral dust aerosols by electric forces

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95661/1/grl21575.pd

Quasielastic 12C(e,e'p) Reaction at High Momentum Transfer

We measured the 12C(e,e'p) cross section as a function of missing energy in parallel kinematics for (q,w) = (970 MeV/c, 330 MeV) and (990 MeV/c, 475 MeV). At w=475 MeV, at the maximum of the quasielastic peak, there is a large continuum (E_m > 50 MeV) cross section extending out to the deepest missing energy measured, amounting to almost 50% of the measured cross section. The ratio of data to DWIA calculation is 0.4 for both the p- and s-shells. At w=330 MeV, well below the maximum of the quasielastic peak, the continuum cross section is much smaller and the ratio of data to DWIA calculation is 0.85 for the p-shell and 1.0 for the s-shell. We infer that one or more mechanisms that increase with $\omega$ transform some of the single-nucleon-knockout into multinucleon knockout, decreasing the valence knockout cross section and increasing the continuum cross section.Comment: 14 pages, 7 figures, Revtex (multicol, prc and aps styles), to appear in Phys Rev

A systematic review of instruments that assess the implementation of hospital quality management systems.

PURPOSE: Health-care providers invest substantial resources to establish and implement hospital quality management systems. Nevertheless, few tools are available to assess implementation efforts and their effect on quality and safety outcomes. This review aims to (i) identify instruments to assess the implementation of hospital quality management systems, (ii) describe their measurement properties and (iii) assess the effects of quality management on quality improvement and quality of care outcomes. DATA SOURCES: We performed a systematic literature search from 1990 to 2011 in PubMed, CINAHL, EMBASE, Cochrane Library and Web of Science. In addition, we used snowball strategies, screened the reference lists of eligible papers, reviewed grey literature and contacted experts in the field. STUDY SELECTION: and data extraction Two reviewers screened eligible papers based on pre-defined inclusion and exclusion criteria and all authors extracted data. Eligible papers are described in terms of general characteristics (settings, type and level of respondents, mode of data collection), methodological properties (sampling strategy, item derivation, conceptualization of quality management, assessment of reliability and validity, scoring) and application/implementation (accounting for context, organizational adaptations, sensitivity to change, deployment and effect size). RESULTS: Eighteen papers were deemed eligible for inclusion. While some common domains emerged in measurement conceptualization, substantial differences in scope persist. The instruments' measurement properties were insufficiently described and only few instruments assessed links between the implementation of quality management systems (QMS) and improvement strategies or outcomes. CONCLUSIONS: There is currently no well-established measure to assess the implementation and effectiveness of quality management systems. Future research should address this gap