Hydroxyl as a Tracer of H2 in the Envelope of MBM40

We observed 51 positions in the OH 1667 MHz main line transitions in the translucent, high latitude cloud MBM40. We detected OH emission in 8 out of 8 positions in the molecular core of the cloud and 24 out of 43 in the surrounding, lower extinction envelope and periphery of the cloud. Using a linear relationship between the integrated OH line intensity and E(B-V), we estimate the mass in the core, the envelope, and the periphery of the cloud to be 4, 8, and 5 solar masses. As much as a third of the total cloud mass may be found in the in the periphery (E(B-V) $<$ 0.12 mag) and about a half in the envelope (0.12 $\le$ E(B-V) $\le$ 0.17 mag). If these results are applicable to other translucent clouds the OH 1667 MHz line is an excellent tracer of gas in very low extinction regions and high-sensitivity mapping of the envelopes of molecular clouds may reveal the presence of significant quantities of molecular mass.Comment: 26 pages, 3 figures, and 5 table

Stoichiometry control of sputtered CuCl thin films: Influence on ultraviolet emission properties

We demonstrate that the chemical composition of the sputtered CuCl thin films could be finely controlled by adjusting the bias to the substrate. The films deposited without any intentional bias were Cl rich (CuCl1+x), a bias of −22 V yielded stoichiometric CuCl, and a further increase in the negative bias resulted in Cl deficient films (CuCl1−x). The crystalline and optical properties were found to be associated with the chemical composition. Cl rich films showed a deep level green emission at around 515 nm in addition to ultraviolet (UV) excitonic emission. The stoichiometric films have higher optical quality, exhibiting a sharp UV emission at around 385 nm at room temperature, compared to nonstoichiometric samples. Visible luminescence related to deep level defects was not observed in the stoichiometric films. Changes in energy of the flux from the target and the subsequent ion bombardment on the substrate surface are correlated with the variations in chemical composition and their impact on the film microstructure and UV emission

Scarcity of fixed carbon transfer in a model microbial phototroph–heterotroph interaction

Although the green alga Chlamydomonas reinhardtii has long served as a reference organism, few studies have interrogated its role as a primary producer in microbial interactions. Here, we quantitatively investigated C. reinhardtii's capacity to support a heterotrophic microbe using the established coculture system with Mesorhizobium japonicum, a vitamin B12-producing α-proteobacterium. Using stable isotope probing and nanoscale secondary ion mass spectrometry (nanoSIMS), we tracked the flow of photosynthetic fixed carbon and consequent bacterial biomass synthesis under continuous and diurnal light with single-cell resolution. We found that more 13C fixed by the alga was taken up by bacterial cells under continuous light, invalidating the hypothesis that the alga's fermentative degradation of starch reserves during the night would boost M. japonicum heterotrophy. 15NH4 assimilation rates and changes in cell size revealed that M. japonicum cells reduced new biomass synthesis in coculture with the alga but continued to divide-a hallmark of nutrient limitation often referred to as reductive division. Despite this sign of starvation, the bacterium still synthesized vitamin B12 and supported the growth of a B12-dependent C. reinhardtii mutant. Finally, we showed that bacterial proliferation could be supported solely by the algal lysis that occurred in coculture, highlighting the role of necromass in carbon cycling. Collectively, these results reveal the scarcity of fixed carbon in this microbial trophic relationship (particularly under environmentally relevant light regimes), demonstrate B12 exchange even during bacterial starvation, and underscore the importance of quantitative approaches for assessing metabolic coupling in algal-bacterial interactions

Using Open Public Meetings and Elections to Promote Inward Transparency and Accountability: Lessons from Zambia

BackgroundCommunity-led governance can ensure that leaders are accountable to the populations they serve and strengthen health systems for maternal care. A key aspect of democratic accountability is electing respective governance bodies, in this case community boards, and holding public meetings to inform community members about actions taken on their behalf. After helping build and open 10 maternity waiting homes (MWHs) in rural Zambia as part of a randomized controlled trial, we assisted community governance committees to plan and execute annual meetings to present performance results and, where needed, to elect new board members. MethodsWe applied a principally qualitative design using observation and analysis of written documentation of public meetings to answer our research question: how do governance committees enact inward transparency and demonstrate accountability to their communities. The analysis measured participation and stakeholder representation at public meetings, the types and purposes of accountability sought by community members as evidenced by questions asked of the governance committee, and responsiveness of the governance committee to issues raised at public meetings. ResultsPublic meetings were attended by 6 out of 7 possible stakeholder groups, and reports were generally transparent. Stakeholders asked probing questions focused mainly on financial performance. Governance committee members were responsive to questions raised by participants, with 59% of answers rated as fully or mostly responsive (showing understanding of and answering the question). Six of the 10 sites held elections to re-elect or replace governance committee members. Only 2 sites reached the target set by local stakeholder committees of 50% female membership, down from 3 at formation. To further improve transparency and accountability, community governance committees need to engage in advance preparation of reports, and should consult with stakeholders on broader measures for performance assessment. Despite receiving training, community-level governance committees lacked understanding of the strategic purpose of open public meetings and elections, and how these relate to democratic accountability. They were therefore not motivated to engage in tactics to manage stakeholders effectively. ConclusionWhile open meetings and elections have potential to enhance good governance at the community level, continuous training and mentoring are needed to build capacity and enhance sustainability

A Quantitative Content Analysis of Mercer University Theses

Quantitative content analysis of a body of research not only helps budding researchers understand the culture, language, and expectations of scholarship, it helps identify deficiencies and inform policy and practice. Because of these benefits, an analysis of a census of 980 Mercer University M.Ed., Ed.S., and doctoral theses was conducted. Each thesis was coded on 10 variables. The descriptive characteristics of the theses, the predictors of the length of the theses, and the predictors of the type of research method used were investigated. The main results were that: (a) the vast majority of thesis authors was female, (b) the number of qualitative theses was on the rise, (c) there were slight variations in research method and length based on location of publication, (d) the page length of M.Ed. theses had been slightly decreasing over time, (e) mathematics instruction was the most frequent subject descriptor of theses, and (f) the proportion of male authors increased over time

Nodal dynamics, not degree distributions, determine the structural controllability of complex networks

Structural controllability has been proposed as an analytical framework for making predictions regarding the control of complex networks across myriad disciplines in the physical and life sciences (Liu et al., Nature:473(7346):167-173, 2011). Although the integration of control theory and network analysis is important, we argue that the application of the structural controllability framework to most if not all real-world networks leads to the conclusion that a single control input, applied to the power dominating set (PDS), is all that is needed for structural controllability. This result is consistent with the well-known fact that controllability and its dual observability are generic properties of systems. We argue that more important than issues of structural controllability are the questions of whether a system is almost uncontrollable, whether it is almost unobservable, and whether it possesses almost pole-zero cancellations.Comment: 1 Figures, 6 page

Maize leaf PPDK regulatory protein isoform-2 is specific to bundle sheath chloroplasts and paradoxically lacks a Pi-dependent PPDK activation activity

In C4 plants, the pyruvate phosphate dikinase regulatory protein (PDRP) regulates the C4 pathway enzyme pyruvate phosphate dikinase (PPDK) in response to changes in incident light intensity. In maize (Zea mays) leaves, two distinct isoforms of PDRP are expressed, ZmPDRP1 and ZmPDRP2. The properties and C4 function of the ZmPDRP1 isoform are well understood. However, the PDRP2 isoform has only recently been identified and its properties and function(s) in maize leaves are unknown. We therefore initiated an investigation into the maize PDRP2 isoform by performing a side by side comparison of its enzyme properties and cell-specific distribution with PDRP1. In terms of enzyme functionality, PDRP2 was found to possess the same protein kinase-specific activity as PDRP1. However, the PDRP2 isoform was found to lack the phosphotransferase activity of the bifunctional PDRP1 isoform except when PDRP2 in the assays is elevated 5- to 10-fold. A primarily immuno-based approach was used to show that PDRP1 is strictly expressed in mesophyll cells and PDRP2 is strictly expressed in bundle sheath strand cells (BSCs). Additionally, using in situ immunolocalization, we establish a regulatory target for PDRP2 by showing a significant presence of C4 PPDK in BSC chloroplasts. However, a metabolic role for PPDK in this compartment is obscure, assuming PPDK accumulating in this compartment would be irreversibly inactivated each dark cycle by a monofunctional PDRP2

Bringing exploratory learning online: problem-solving before instruction improves remote undergraduate physics learning

STEM undergraduate instructors teaching remote courses often use traditional lecture-based instruction, despite evidence that active learning methods improve student engagement and learning outcomes. One simple way to use active learning online is to incorporate exploratory learning. In exploratory learning, students explore a novel activity (e.g., problem solving) before a lecture on the underlying concepts and procedures. This method has been shown to improve learning outcomes during in-person courses, without requiring the entire course to be restructured. The current study examined whether the benefits of exploratory learning extend to a remote undergraduate physics lesson, taught synchronously online. Undergraduate physics students (N = 78) completed a physics problem-solving activity either before instruction (explore-first condition) or after (instruct-first condition). Students then completed a learning assessment of the problem-solving procedures and underlying concepts. Despite lower accuracy on the learning activity, students in the explore-first condition demonstrated better understanding on the assessment, compared to students in the instruct-first condition. This finding suggests that exploratory learning can serve as productive failure in online courses, challenging students but improving learning, compared to the more widely-used lecture-then-practice method