Quantifying the effects of hydrogen on carbon assimilation in a seafloor microbial community associated with ultramafic rocks

Thermodynamic models predict that H2 is energetically favorable for seafloor microbial life, but how H2 affects anabolic processes in seafloor-associated communities is poorly understood. Here, we used quantitative 13C DNA stable isotope probing (qSIP) to quantify the effect of H2 on carbon assimilation by microbial taxa synthesizing 13C-labeled DNA that are associated with partially serpentinized peridotite rocks from the equatorial Mid-Atlantic Ridge. The rock-hosted seafloor community was an order of magnitude more diverse compared to the seawater community directly above the rocks. With added H2, peridotite-associated taxa increased assimilation of 13C-bicarbonate and 13C-acetate into 16S rRNA genes of operational taxonomic units by 146% (±29%) and 55% (±34%), respectively, which correlated with enrichment of H2-oxidizing NiFe-hydrogenases encoded in peridotite-associated metagenomes. The effect of H2 on anabolism was phylogenetically organized, with taxa affiliated with Atribacteria, Nitrospira, and Thaumarchaeota exhibiting the most significant increases in 13C-substrate assimilation in the presence of H2. In SIP incubations with added H2, an order of magnitude higher number of peridotite rock-associated taxa assimilated 13C-bicarbonate, 13C-acetate, and 13C-formate compared to taxa that were not associated with peridotites. Collectively, these findings indicate that the unique geochemical nature of the peridotite-hosted ecosystem has selected for H2-metabolizing, rock-associated taxa that can increase anabolism under high H2 concentrations. Because ultramafic rocks are widespread in slow-, and ultraslow-spreading oceanic lithosphere, continental margins, and subduction zones where H2 is formed in copious amounts, the link between H2 and carbon assimilation demonstrated here may be widespread within these geological settings

Nonlinear DC-response in Composites: a Percolative Study

The DC-response, namely the $I$-$V$ and $G$-$V$ charateristics, of a variety of composite materials are in general found to be nonlinear. We attempt to understand the generic nature of the response charactersistics and study the peculiarities associated with them. Our approach is based on a simple and minimal model bond percolative network. We do simulate the resistor network with appropritate linear and nonlinear bonds and obtain macroscopic nonlinear response characteristics. We discuss the associated physics. An effective medium approximation (EMA) of the corresponding resistor network is also given.Comment: Text written in RevTEX, 15 pages (20 postscript figures included), submitted to Phys. Rev. E. Some minor corrections made in the text, corrected one reference, the format changed (from 32 pages preprint to 15 pages

Implementation strategies to promote measurement-based care in schools: evidence from mental health experts across the USA

Background Despite an established taxonomy of implementation strategies, minimal guidance exists for how to select and tailor strategies to specific practices and contexts. We employed a replicable method to obtain stakeholder perceptions of the most feasible and important implementation strategies to increase mental health providers’ use of measurement-based care (MBC) in schools. MBC is the routine use of patient-reported progress measures throughout treatment to inform patient-centered, data-driven treatment adjustments. Methods A national sample of 52 school mental health providers and researchers completed two rounds of modified Delphi surveys to rate the relevance, importance, and feasibility of 33 implementation strategies identified for school settings. Strategies were reduced and definitions refined using a multimethod approach. Final importance and feasibility ratings were plotted on “go-zone” graphs and compared across providers and researchers to identify top-rated strategies. Results The initial 33 strategies were rated as “relevant” or “relevant with changes” to MBC in schools. Importance and feasibility ratings were high overall for both survey rounds; on a scale of 1 to 5, importance ratings (3.61–4.48) were higher than feasibility ratings (2.55–4.06) on average. Survey 1 responses resulted in a reduced, refined set of 21 strategies, and six were rated most important and feasible on Survey 2: (1) assess for readiness and identify barriers and facilitators; (2) identify and prepare champions; (3) develop a usable implementation plan; (4) offer a provider-informed menu of free, brief measures; (5) develop and provide access to training materials; and (6) make implementation easier by removing burdensome documentation tasks. Provider and researcher ratings were not significantly different, with a few exceptions: providers reported higher feasibility and importance of removing burdensome paperwork than researchers, providers reported higher feasibility of train-the trainer approaches than researchers, and researchers reported higher importance of monitoring fidelity than providers. Conclusions The education sector is the most common setting for child and adolescent mental health service delivery in the USA. Effective MBC implementation in schools has the potential to elevate the quality of care received by many children, adolescents, and their families. This empirically derived, targeted list of six implementation strategies offers potential efficiencies for future testing of MBC implementation in schools

The Electrical-Thermal Switching in Carbon Black-Polymer Composites as a Local Effect

Following the lack of microscopic information about the intriguing well-known electrical-thermal switching mechanism in Carbon Black-Polymer composites, we applied atomic force microscopy in order to reveal the local nature of the process and correlated it with the characteristics of the widely used commercial switches. We conclude that the switching events take place in critical interparticle tunneling junctions that carry most of the current. The macroscopic switched state is then a result of a dynamic-stationary state of fast switching and slow reconnection of the corresponding junctions.Comment: 14 pages, 5 figures,Typographic correctio

Piezoresistivity and conductance anisotropy of tunneling-percolating systems

Percolating networks based on interparticle tunneling conduction are shown to yield a logarithmic divergent piezoresistive response close to the critical point as long as the electrical conductivity becomes nonuniversal. At the same time, the piezoresistivity or, equivalently, the conductivity anisotropy exponent $\lambda$ remains universal also when the conductive exponent is not, suggesting a purely geometric origin of $\lambda$. We discuss our results in relation to the nature of transport for a variety of materials such as carbon-black--polymer composites and RuO_2-glass systems which show nonuniversal transport properties and coexistence between tunneling and percolating behaviors.Comment: 6 pages, 3 figures, Added discussion on experiment

Scapegoat: John Dewey and the character education crisis

Many conservatives, including some conservative scholars, blame the ideas and influence of John Dewey for what has frequently been called a crisis of character, a catastrophic decline in moral behavior in the schools and society of North America. Dewey’s critics claim that he is responsible for the undermining of the kinds of instruction that could lead to the development of character and the strengthening of the will, and that his educational philosophy and example exert a ubiquitous and disastrous influence on students’ conceptions of moral behavior. This article sets forth the views of some of these critics and juxtaposes them with what Dewey actually believed and wrote regarding character education. The juxtaposition demonstrates that Dewey neither called for nor exemplified the kinds of character-eroding pedagogy his critics accuse him of championing; in addition, this paper highlights the ways in which Dewey argued consistently and convincingly that the pedagogical approaches advocated by his critics are the real culprits in the decline of character and moral education