Crystal Structures of Polymerized Fullerides AC60, A=K, Rb, Cs and Alkali-mediated Interactions

Starting from a model of rigid interacting C60 polymer chains on an orthorhombic lattice, we study the mutual orientation of the chains and the stability of the crystalline structures Pmnn and I2/m. We take into account i) van der Waals interactions and electric quadrupole interactions between C60 monomers on different chains as well as ii) interactions of the monomers with the surrounding alkali atoms. The direct interactions i) always lead to an antiferrorotational structure Pmnn with alternate orientation of the C60 chains in planes (001). The interactions ii) with the alkalis consist of two parts: translation-rotation (TR) coupling where the orientations of the chains interact with displacements of the alkalis, and quadrupolar electronic polarizability (ep) coupling, where the electric quadrupoles on the C60 monomers interact with induced quadrupoles due to excited electronic d states of the alkalis. Both interactions ii) lead to an effective orientation-orientation interaction between the C60 chains and always favor the ferrorotational structure I2/m where C60 chains have a same orientation. The structures Pmnn for KC60 and I2/m for Rb- and CsC60 are the result of a competition between the direct interaction i) and the alkali-mediated interactions ii). In Rb- and CsC60 the latter are found to be dominant, the preponderant role being played by the quadrupolar electronic polarizability of the alkali ions.Comment: J.Chem.Phys., in press, 14 pages, 3 figures, 8 table

Ecological theory predicts ecosystem stressor interactions in freshwater communities, but highlights the strengths and weaknesses of the additive null model

Understanding and predicting how multiple co-occurring environmental stressors combine to affect biodiversity and ecosystem services is an on-going grand challenge for ecology. So far progress has been made through accumulating large numbers of smaller-scale individual studies that are then investigated by meta-analyses to look for general patterns. In particular there has been an interest in checking for so-called ecological surprises where stressors interact in a synergistic manner. Recent reviews suggest that such synergisms do not dominate, but few other generalities have emerged. This lack of general prediction and understanding may be due in part to a dearth of ecological theory that can generate clear hypotheses and predictions to tested against empirical data. Here we close this gap by analysing food web models based upon classical ecological theory and comparing their predictions to a large (546 interactions) dataset for the effects of pairs of stressors on freshwater communities, using trophic- and population-level metrics of abundance, density, and biomass as responses. We find excellent overall agreement between the stochastic version of our models and the experimental data, and both conclude additive stressor interactions are the most frequent, but that meta-analyses report antagonistic summary interaction classes. Additionally, we show that the statistical tests used to classify the interactions are very sensitive to sampling variation. It is therefore likely that current weak sampling and low sample sizes are masking many non-additive stressor interactions, which our theory predicts to dominate when sampling variation is removed. This leads us to suspect ecological surprises may be more common than currently reported. Our results highlight the value of developing theory in tandem with empirical tests, and the need to examine the robustness of statistical machinery, especially the widely-used null models, before we can draw strong conclusions about how environmental drivers combine

Applying Lean: Implementation of a Rapid Triage and Treatment System

Objective: Emergency department (ED) crowding creates issues with patient satisfaction, long wait times and leaving the ED without being seen by a doctor (LWBS). Our objective was to evaluate how applying Lean principles to develop a Rapid Triage and Treatment (RTT) system affected ED metrics in our community hospital.Methods: Using Lean principles, we made ED process improvements that led to the RTT system. Using this system, patients undergo a rapid triage with low-acuity patients seen and treated by a physician in the triage area. No changes in staffing, physical space or hospital resources occurred during the study period. We then performed a retrospective, observational study comparing hospital electronic medical record data six months before and six months after implementation of the RTT system.Results: ED census was 30,981 in the six months prior to RTT and 33,926 after. Ambulance arrivals, ED patient acuity and hospital admission rates were unchanged throughout the study periods. Mean ED length of stay was longer in the period before RTT (4.2 hours, 95% confidence interval [CI] = 4.2-4.3; standard deviation [SD] = 3.9) than after (3.6 hours, 95% CI = 3.6-3.7; SD = 3.7). Mean ED arrival to physician start time was 62.2 minutes (95% CI = 61.5-63.0; SD = 58.9) prior to RTT and 41.9 minutes (95% CI = 41.5-42.4; SD = 30.9) after. The LWBS rate for the six months prior to RTT was 4.5% (95% CI = 3.1-5.5) and 1.5% (95% CI = 0.6-1.8) after RTT initiation.Conclusion: Our experience shows that changes in ED processes using Lean thinking and available resources can improve efficiency. In this community hospital ED, use of an RTT system decreased patient wait times and LWBS rates. [West J Emerg Med. 2011;12(2):184-191.

An Input-output Model of the Lower Rio Grande Region of Texas

The Lower Rio Grande Region is composed of the nineteen southernmost counties in Texas. The major portion of the population of the region resides along the Rio Grande River in border communities and Corpus Christi on the Gulf of Mexico. The primary economic activities are crop production, ranching, shrimping, oil production, and commercial activities. The existence of social costs, in conjunction with a desire for increased economic development, created the need that led to the development of a regional Input-Output Model. The Input-Output Model consists of five tables. The Transactions Table was developed from primary and secondary data. The estimated transactions were adjusted to form a producer-price matrix. Both transportation charges and costs of goods sold were allocated to appropriate final demand sectors. The remaining four tables were derived from the Transactions Table. They include a Direct Coefficients Table, a Direct and Indirect Coefficients Table, a Labor Coefficients Table, and a table that closes the model with respect to the household (The Closed Model Table). The uses of the Input-Output tables are explained in relation to the historical problems that have arisen in the Lower Rio Grande Region. In addition, examples are given on how the model can be used to develop information for planning

MicroRNA29a regulates IL-33-mediated tissue remodelling in tendon disease

MicroRNA (miRNA) has the potential for cross-regulation and functional integration of discrete biological processes during complex physiological events. Utilizing the common human condition tendinopathy as a model system to explore the cross-regulation of immediate inflammation and matrix synthesis by miRNA we observed that elevated IL-33 expression is a characteristic of early tendinopathy. Using in vitro tenocyte cultures and in vivo models of tendon damage, we demonstrate that such IL-33 expression plays a pivotal role in the transition from type 1 to type 3 collagen (Col3) synthesis and thus early tendon remodelling. Both IL-33 effector function, via its decoy receptor sST2, and Col3 synthesis are regulated by miRNA29a. Downregulation of miRNA29a in human tenocytes is sufficient to induce an increase in Col3 expression. These data provide a molecular mechanism of miRNA-mediated integration of the early pathophysiologic events that facilitate tissue remodelling in human tendon after injury

Targeting danger molecules in tendinopathy: the HMGB1/TLR4 axis

Objectives: To seek evidence of the danger molecule, high-mobility group protein B1 (HMGB1) expression in human tendinopathy and thereafter, to explore mechanisms where HMGB1 may regulate inflammatory mediators and matrix regulation in human tendinopathy. Methods: Torn supraspinatus tendon (established pathology) and matched intact subscapularis tendon (representing ‘early pathology’) biopsies were collected from patients undergoing arthroscopic shoulder surgery. Control samples of subscapularis tendon were collected from patients undergoing arthroscopic stabilisation surgery. Markers of inflammation and HMGB1 were quantified by reverse transcriptase PCR (RT-PCR) and immunohistochemistry. Human tendon-derived primary cells were derived from hamstring tendon tissue obtained during hamstring tendon anterior cruciate ligament reconstruction and used through passage 3. In vitro effects of recombinant HMGB1 on tenocyte matrix and inflammatory potential were measured using quantitative RT-PCR, ELISA and immunohistochemistry staining. Results: Tendinopathic tissues demonstrated significantly increased levels of the danger molecule HMGB1 compared with control tissues with early tendinopathy tissue showing the greatest expression. The addition of recombinant human HMGB1 to tenocytes led to significant increase in expression of a number of inflammatory mediators, including interleukin 1 beta (IL-1β), IL-6, IL-33, CCL2 and CXCL12, in vitro. Further analysis demonstrated rhHMGB1 treatment resulted in increased expression of genes involved in matrix remodelling. Significant increases were observed in Col3, Tenascin-C and Decorin. Moreover, blocking HMGB1 signalling via toll-like receptor 4 (TLR4) silencing reversed these key inflammatory and matrix changes. Conclusion: HMGB1 is present in human tendinopathy and can regulate inflammatory cytokines and matrix changes. We propose HMGB1 as a mediator driving the inflammatory/matrix crosstalk and manipulation of the HMGB1/TLR4 axis may offer novel therapeutic approaches targeting inflammatory mechanisms in the management of human tendon disorders

The biosynthetic gene cluster for the anticancer drug bleomycin from \u3ci\u3eStreptomyces verticillus\u3c/i\u3e ATCC15003 as a model for hybrid peptide–polyketide natural product biosynthesis

The hybrid peptide–polyketide backbone of bleomycin (BLM) is assembled by the BLM megasynthetase that consists of both nonribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) modules. BlmIX/BlmVIII/BlmVII constitute a natural hybrid NRPS/PKS/NRPS system, serving as a model for both hybrid NRPS/PKS and PKS/NRPS systems. Sequence analysis and functional comparison of domains and modules of BlmIX/BlmVIII/BlmVII with those of nonhybrid NRPS and PKS systems suggest that (1) the same catalytic sites appear to be conserved in both hybrid NRPS–PKS and nonhybrid NRPS or PKS systems, with the exception of the KS domains in the hybrid NRPS/PKS systems that are unique; (2) specific interpolypeptide linkers may play a critical role in intermodular communication to facilitate transfer of the growing intermediates between the interacting NRPS and/or PKS modules; and (3) posttranslational modification of the BLM megasynthetase has been accomplished by a single PPTase with a broad substrate specificity toward the apo forms of both acyl carrier proteins (ACPs) and peptidyl carrier proteins (PCPs)

Feasibility and systems definition study for Microwave Multi-Application Payload (MMAP)

Work completed on three Shuttle/Spacelab experiments is examined: the Adaptive Multibeam Phased Array Antenna (AMPA) Experiment, Electromagnetic Environment Experiment (EEE) and Millimeter Wave Communications Experiment (MWCE). Results included the definition of operating modes, sequence of operation, radii of operation about several ground stations, signal format, foot prints of typical orbits and preliminary definition of ground and user terminals. Conceptual hardware designs, Spacelab interfaces, data handling methods, experiment testing and verification studies were included. The MWCE-MOD I was defined conceptually for a steerable high gain antenna