bluuebunny/crossref_metadata_2025 huggingface dataset:
The high‐temperature tribological properties of Si‐DLC films
Authors: Yang Baoping , Zheng Yu , Zhang Bin , Wei Li , Zhang Junyan
Published: July 2012

The tribological properties of Silicon‐containing diamond‐like‐carbon (Si‐DLC) films, deposited by magnetron sputtering Si target in methane/argon atmosphere, were studied in comparison with diamond‐like‐carbon (DLC) films. The DLC films disappeared because of the oxidation in the air at 500 °C, whereas the Si‐DLC films still remained, implying that the addition of Si improved significantly the thermal stability of DLC films. Retarded hydrogen release from DLC film at high temperature and silicon oxide on the surface might have contributed to lower friction coefficient of the Si‐DLC films both after annealing treatment and in situ high‐temperature environment. Copyright © 2012 John Wiley & Sons, Ltd.
The impact of additional life‐table variables on excess mortality estimates
Authors: Grafféo Nathalie , Jooste Valérie , Giorgi Roch
Published: July 2012

Regression‐based relative survival models are commonly used in population‐based cancer studies to estimate the real impact on the excess mortality of covariates that influence overall mortality. Usually, the mortality observed in a study cohort is corrected by the expected mortality hazard in the general population, which is given by life tables provided by national statistics institutes. These life tables are stratified by age, sex, calendar year, and, sometimes, other demographic data (ethnicity, deprivation, and others). However, in most cases, the same demographic data are not available for the study cohort and the general population; this leads to differences between the expected mortality of the general population and that of the study cohort. More generally, the absence of some demographic variables in life tables may introduce a measurement bias into the estimation of the excess mortality. In the present article, we used a simulation approach with different plausible scenarios to evaluate the impact of an additional life‐table variable on excess mortality estimates and study the extent and the direction of the biases in estimating the effect of each covariate on the excess mortality. We showed that the use of life table that lacks stratification by a variable present in the excess hazard model results in a measurement bias not only in the estimate of the effect of this variable but also, to a lesser extent, in the estimates of the effects of the other covariates included in the model. We also demonstrated this measurement bias by a population‐based colorectal cancer analysis. Copyright © 2012 John Wiley & Sons, Ltd.
The analysis of record‐linked data using multiple imputation with data value priors
Authors: Goldstein Harvey , Harron Katie , Wade Angie
Published: July 2012

Probabilistic record linkage techniques assign match weights to one or more potential matches for those individual records that cannot be assigned ‘unequivocal matches’ across data files. Existing methods select the single record having the maximum weight provided that this weight is higher than an assigned threshold. We argue that this procedure, which ignores all information from matches with lower weights and for some individuals assigns no match, is inefficient and may also lead to biases in subsequent analysis of the linked data. We propose that a multiple imputation framework be utilised for data that belong to records that cannot be matched unequivocally. In this way, the information from all potential matches is transferred through to the analysis stage. This procedure allows for the propagation of matching uncertainty through a full modelling process that preserves the data structure. For purposes of statistical modelling, results from a simulation example suggest that a full probabilistic record linkage is unnecessary and that standard multiple imputation will provide unbiased and efficient parameter estimates. Copyright © 2012 John Wiley & Sons, Ltd.
The power of imperfect imitation
Authors: Posen Hart E. , Lee Jeho , Yi Sangyoon
Published: July 2012

We examine the power and limitations of imitation. Naive intuition may hold that the efficacy of imitation would be diminished by imperfections in copying high‐performing firms. Employing a computational model, we study the dynamics of imitation when firms are subject to bounded rationality that limits their ability to copy the market leader. We find that imperfect imitation can generate unexpectedly good outcomes for follower firms—indeed, better than the outcomes achieved if they were perfect imitators. Moreover, imperfect imitation, from time to time, enables follower firms to surpass superior firms. These findings suggest there is an adaptive role to mechanisms, such as bounded rationality, that make perfect imitation difficult. Copyright © 2012 John Wiley & Sons, Ltd.
Hot topics for debate in prostate cancer: part 1
Authors: Payne Heather A. , Parker Chris , Malik Zafar
Published: July 2012

This report is based on a seminar held during the 8th Annual Meeting of the British Uro‐oncology Group in York last September. Hot topics for debate covered in part 1 of this article are the use of active surveillance for intermediate‐risk prostate cancer and cardiovascular risks in the hormonal management of locally advanced prostate cancer. All participants, most of whom were clinical oncologists, were invited to contribute and respond to set questions using a keypad voting system. Copyright © 2012 John Wiley & Sons
Visual Representations in Second Graders' Information Book Compositions
Authors: Coleman Julianne M. , Bradley Linda Golson , Donovan Carol A.
Published: July 2012

This paper describes the visuals second grade students included in their own information book compositions during a science unit on weather during which multimodal science trade books on the topic of weather were read aloud. First, the multimodal nature of the information books used in the unit are described. Second, the teacher's talk about visual representations during read alouds of books on weather is presented. And third, the children's own information books about weather topics are examined for inclusion of labeled pictorial illustrations with accompanying captions and graphical representations. These analyses reveal that 1) information book authors vary in their use of visual information, 2) some graphics may be more salient for children, and 3) children's use of pictorial illustrations and graphical representations in their own compositions seems to be impacted by both teacher attention to particular types of visual representations and immersion in information book graphics.
Epoxidized Mesua ferrea L. seed oil‐plasticized thermostable PVC and PVC‐clay nanocomposites
Authors: Das Gautam , Karak Niranjan
Published: July 2012

The use of vegetable‐oil‐based polymeric plasticizers with nanotechnology can create new applications for plasticized poly(vinyl chloride) (PVC). Epoxidized Mesua ferrea L. (Ceylon Ironwood) seed oil was used as a plasticizer for PVC. Further, nanocomposites were prepared through an ex‐situ technique using epoxidized‐oil‐swelled organically modified montmorillonite (5 wt%) and PVC. Notable improvement in thermal and processing characteristics of the nanocomposites was observed over those of the virgin polymer (in both unplasticized and plasticized PVC), as studied by TGA. The prepared nanocomposites were characterized by FTIR, SEM, TEM, and XRD techniques. A dramatic decrease in viscosity (7‐fold) was observed in THF for a 10% solution of epoxidized‐oil‐modified PVC compared to unplasticized PVC in THF, as measured by Brookfield viscometer. Isothermal analysis at three different temperatures (100, 150, and 200°C) reveals sufficient stability of the epoxidized oil modified PVC nanocomposites, as confirmed by gravimetric and FTIR analysis. Augmentation of thermostability and good retention of mechanical properties of the (Mesua ferrea L.)‐plasticized‐PVC/clay nanocomposites with respect to rigid PVC vouch for the utility of the former as advanced industrial materials. J. VINYL ADDIT. TECHNOL., 18:168–177, 2012. © 2012 Society of Plastics Engineers
Synthesis and characterization of a new diol‐functionalized s‐triazine‐based polymerizable hindered amine light stabilizer
Authors: Mehare Rupali S. , Lonkar Sunil P. , Singh R.P.
Published: July 2012

A new diol‐functionalized triazine‐based polymerizable hindered amine light stabilizer (HALS) was synthesized in two steps. First, selective synthesis of an s‐triazine containing two HALS moieties as substituents was accomplished by using phase‐transfer catalysis. This step required the establishment of optimum reaction conditions (type of two‐phase system, best solvent, and catalyst). In the second step, the substituted triazine was treated with diethanolamine to introduce polymerizable diol functionality. The resulting product should act as a light stabilizer, since it contains two HALS moieties anchored to a thermally stable s‐triazine unit. Moreover, incorporation of the diol into a polymeric material might be expected to impart prolonged stability in weathering environments. Characterization of the diol was accomplished by using Fourier transform infrared spectroscopy (FTIR), 'H NMR, and mass spectrometry. J. VINYL ADDIT. TECHNOL., 18:204–208, 2012. © 2012 Society of Plastics Engineers
Monitoring wind turbine gearboxes
Authors: Feng Yanhui , Qiu Yingning , Crabtree Christopher J. , Long Hui , Tavner Peter J.
Published: July 2012

Concerns amongst wind turbine (WT) operators about gearbox reliability arise from complex repair procedures, high replacement costs and long downtimes leading to revenue losses. Therefore, reliable monitoring for the detection, diagnosis and prediction of such faults are of great concerns to the wind industry. Monitoring of WT gearboxes has gained importance as WTs become larger and move to more inaccessible locations. This paper summarizes typical WT gearbox failure modes and reviews supervisory control and data acquisition (SCADA) and condition monitoring system (CMS) approaches for monitoring them. It then presents two up‐to‐date monitoring case studies, from different manufacturers and types of WT, using SCADA and CMS signals.

The first case study, applied to SCADA data, starts from basic laws of physics applied to the gearbox to derive robust relationships between temperature, efficiency, rotational speed and power output. The case study then applies an analysis, based on these simple principles, to working WTs using SCADA oil temperature rises to predict gearbox failure.

The second case study focuses on CMS data and derives diagnostic information from gearbox vibration amplitudes and oil debris particle counts against energy production from working WTs.

The results from the two case studies show how detection, diagnosis and prediction of incipient gearbox failures can be carried out using SCADA and CMS signals for monitoring although each technique has its particular strengths. It is proposed that in the future, the wind industry should consider integrating WT SCADA and CMS data to detect, diagnose and predict gearbox failures.Copyright © 2012 John Wiley & Sons, Ltd.
Decomposition of the windiness index in the Netherlands for the assessment of future long‐term wind supply
Authors: Bakker A. M. R. , Van den Hurk B. J. J. M. , Coelingh J. P.
Published: July 2012

The main windiness index in the Netherlands (Windex‐CBS) has been subject to a decreasing trend since the systematic recording started in 1988. This seriously complicates the estimation of future long‐term wind supply. Therefore, it is necessary to know the main causes of the reported decline.

For this purpose, Windex‐CBS, derived from actual wind turbine yields, is compared with two alternative windiness indices. The first index is based on wind speed observations Wland and the second on geostrophic wind speed Gland. Similar indices are formulated for offshore wind supply in the North Sea, Woff and Goff. High mutual correlations between the indices indicate that they do efficiently account for natural variability. Yet, the trends of the different indices do substantially differ from each other.

The decrease of Windex‐CBS is twice as large as (200%) the decrease of Wland. The trend of the difference between both indices is highly significant. This suggests that the Windex‐CBS is contaminated by operational or methodological factors. Wland does not suffer from such factors and is therefore the preferred measure of wind supply. Copyright © 2012 John Wiley & Sons, Ltd.
Impact of Positive Intraabdominal Lavage Cytology on the Long‐term Prognosis of Colorectal Cancer Patients
Authors: Temesi Rita , Sikorszki László , Bezsilla János , Botos Ákos , Kovács Judit , Tihanyi Tibor
Published: July 2012

Background

Our aim was to investigate the presence of free cancer cells found in lavage cytology specimens taken from the proximity of tumors during the course of curative open and laparoscopic colorectal resections and then examine and compare the long‐term disease outcomes in cases of negative and positive cytology. Based on the results, we were hoping to identify the place of peritumoral lavage cytology among prognostic factors for disease recurrence.

Methods

Between January 1, 2005 and December 31, 2007 intraoperative peritoneal lavage cytology was performed in 145 patients who underwent curative colorectal procedures. In all, 37 of the procedures were laparoscopic resections.

Results

Malignant cells were detected in the intraoperative peritoneal lavage cytology samples from 25 patients. Median follow‐up was 47 months (3–81 months). Among the 25 patients with positive cytology; locoregional recurrence or distant metastasis was found in 14 during this period (56 %), whereas among the 120 patients with negative cytology the incidence was 28 (23 %).

Conclusions

The impact of tumor stage, lymph node status, and peritoneal lavage cytology on recurrence rates is significant. Tumor, nodal, and lavage cytology status can be organized hierarchically in relation to time of recurrence. Cytology is most important, with positivity rendering long‐term prognosis unfavorable. When comparing surgical techniques (open versus laparoscopic), we found no significant difference in recurrence rates. Our study has shown that conventional peritoneal lavage cytology is a prognostic factor in the case of patients undergoing curative colorectal operations.
The Complexities of Governing in a Social Media World
Authors: Philpott Thomas G. , Swettenham Julie
Published: July 2012

The complexity of governing has increased with the Internet's introduction of social media. Boards need to be aware of social media impact upon external stakeholder relations, as well as legal responsibilities within the organization. This paper outlines the various implications of social media that a board needs to consider. A governance framework is used to help put the issues in perspective. The conclusion is that boards need to take social media seriously and ensure that their organization has a social media risk mitigation strategy for external communications, as well as eDiscovery. Various other strategies and tactics are suggested to help boards address the challenge.
The Contribution of Work Environment to Nurses' Assessments of the Quality of Patient Care
Authors: Lepnurm Rein , Dobson Roy , Stamler Lynnette , Persaud David , Keegan David , Brownbridge Brian
Published: July 2012

The quality of patient care was found to be significantly correlated with work environment measures in a quasi-experimental study in the Saskatoon Health Region. Since first line supervisors face multiple pressures in organizing the work of their units, they need to be supported by senior leadership for continuity in instilling a common purpose and shared values to the patient care staff. The role of supervision and leadership is crucial in strategically managing the human, financial and technical resources in our healthcare system, especially when such resources are likely to remain limited.
Diagnosis and treatment of acute otitis media: review
Authors: Toll Edward C , Nunez Desmond A
Published: July 2012

Background:

Acute otitis media is very common, but diagnostic criteria and treatment recommendations vary considerably.

Methods:

Medline, the Cochrane Database of Systematic Reviews and the Cochrane Central Register of Controlled Trials were searched using the key words ‘acute otitis media’ AND ‘diagnosis’ OR ‘diagnostic criteria’ OR ‘definition’, and by combining the terms ‘acute otitis media’ AND ‘guidelines’. PubMed was searched using the key words ‘mastoiditis’ and ‘prevalence’.

Results:

The 11 most recently published guidelines unanimously agreed that adequate analgesia should be prescribed in all cases. The majority recommended that routine antibiotic prescription should be avoided in mild to moderate cases and when there was diagnostic uncertainty in patients two years and older. Antibiotics were recommended in children two years and younger, most commonly a 5-day course of amoxicillin (or a macrolide in patients allergic to penicillin).

Conclusion:

Level 1A evidence shows that selected cases of acute otitis media benefit from antibiotic prescription.
Maintenance of livestock farming may buffer population decline of the Barn SwallowHirundo rustica
Authors: AMBROSINI ROBERTO , RUBOLINI DIEGO , TROVÒ PAOLA , LIBERINI GIOVANNI , BANDINI MARCO , ROMANO ANDREA , SICURELLA BEATRICE , SCANDOLARA CHIARA , ROMANO MARIA , SAINO NICOLA
Published: July 2012

Populations of farmland and long-distance migratory birds have suffered steep, often dramatic, declines in the last few decades. The Barn SwallowHirundo rusticais a small migratory farmland bird that breeds synanthropically in farms, particularly where livestock is reared. Populations of this species have suffered marked declines in different parts of its European breeding range. Here, we first report a dramatic decline of 8.4% per year of the number of breeding pairs and the extinction of 19.6% of the colonies in three agricultural areas in Northern Italy, which differ in general ecological conditions. This decline was estimated on a very large sample of 190 randomly chosen farms where breeding pairs were censused both in 2001 and 2010, and occurred at different rates in the three study areas. Barn Swallows declined most (9.3% per year) in an intensively cultivated area where colonies are widespread, and least (1.3% per year) in a hilly area with a comparatively small density of colonies. Variation in livestock farming significantly influenced population dynamics. Specifically, cessation of livestock farming at a given farm between the two census years resulted in a significantly steeper decline in the number of breeding pairs compared to farms where livestock farming was maintained. Our findings highlight the fact that European populations of Barn Swallows breeding in intensively cultivated agro-ecosystems may become significantly depleted in the next decades, and indicate that maintenance of livestock farming may contribute to buffering the population decline of this species.
Hospitalization Rates Among Dialysis Patients During Hurricane Katrina
Authors: Howard David , Zhang Rebecca , Huang Yijian , Kutner Nancy
Published: July 2012

Introduction

Dialysis centers struggled to maintain continuity of care for dialysis patients during and immediately following Hurricane Katrina's landfall on the US Gulf Coast in August 2005. However, the impact on patient health and service use is unclear.

Problem

The impact of Hurricane Katrina on hospitalization rates among dialysis patients was estimated.

Methods

Data from the United States Renal Data System were used to identify patients receiving dialysis from January 1, 2001 through August 29, 2005 at clinics that experienced service disruptions during Hurricane Katrina. A repeated events duration model was used with a time-varying Hurricane Katrina indicator to estimate trends in hospitalization rates. Trends were estimated separately by cause: surgical hospitalizations, medical, non-renal-related hospitalizations, and renal-related hospitalizations.

Results

The rate ratio for all-cause hospitalization associated with the time-varying Hurricane Katrina indicator was 1.16 (95% CI, 1.05-1.29; P = .004). The ratios for cause-specific hospitalization were: surgery, 0.84 (95% CI, 0.68-1.04; P = .11); renal-related admissions, 2.53 (95% CI, 2.09-3.06); P < .001), and medical non-renal related, 1.04 (95% CI, 0.89-1.20; P = .63). The estimated number of excess renal-related hospital admissions attributable to Katrina was 140, representing approximately three percent of dialysis patients at the affected clinics.

Conclusions

Hospitalization rates among dialysis patients increased in the month following the Hurricane Katrina landfall, suggesting that providers and patients were not adequately prepared for large-scale disasters.

Howard D, Zhang R, Huang Y, Kutner N. Hospitalization rates among dialysis patients during Hurricane Katrina. Prehosp Disaster Med. 2012;27(4):1-5.
An International Expert Delphi Study to Determine Research Needs in Major Incident Management
Authors: Mackway-Jones Kevin , Carley Simon
Published: July 2012

Objective

To collate the opinions of experts and to reach consensus about the research priorities in the management of major incidents.

Design

A three-round e-Delphi study was conducted using an international panel of experts drawn from active researchers and active educators in major incident management. General areas for consideration were derived from the literature analysis undertaken as part of the overall project.

Results

Experts generated 221 statements in 11 topic areas in the first round. Fifty-one of these statements reached consensus in Round 2. A further 23 statements reached consensus in Round 3, leaving 147 statements that did not reach consensus.

Conclusions

An international expert panel reached consensus on 74 topics of research priority in major incidents management. The strongest themes within these topics were education and training, planning, and communication.

Mackway-Jones K, Carley S. An international expert Delphi study to determine research needs in major incident management.Prehosp Disaster Med.2012;27(4):1-8.
Psychological Consequences of Indirect Exposure to Disaster Due to the Haiti Earthquake
Authors: Shultz James M. , Besser Avi , Kelly Fiona , Allen Andrea , Schmitz Susan , Hausmann Vicky , Marcelin Louis Herns , Neria Yuval
Published: July 2012

Introduction

Few studies have focused on the mental health consequences of indirect exposure to disasters caused by naturally occurring hazards. The present study assessed indirect exposure to the 2010 earthquake in Haiti among Haitian-Americans now living in Miami; these subjects had no direct exposure to the earthquake, but retained their cultural identity, language, and connection to family and friends in Haiti.

Methods

Two months following the earthquake a sample of Haitian-Americans was surveyed inquiring about: (1) their psychological reactions to the quake; (2) types of exposures experienced by their family members and friends in Haiti; and (3) symptom levels of (a) major depression, (b) generalized anxiety disorder, (c) complicated grief, (d) mental health status, and (e) physical health status.

Results

Haitian-Americans living in Miami experienced a broad spectrum of indirect exposures to the 2010 earthquake in Haiti. These exposures were strongly associated with psychological distress, trauma-related mental health consequences, and diminished health status. Most notable was the multiplicity of indirect exposures to the on-scene experiences of multiple family members and friends in Haiti.

Conclusions

Consideration should be given to the psychological impact and needs for support among indirectly-exposed populations with strong affiliation to directly-impacted victims.

Shultz JM, Besser A, Kelly F, Allen A, Schmitz S, Hausmann V, Marcelin LH, Neria Y. Psychological consequences of indirect exposure to disaster due to the Haiti earthquake.Prehosp Disaster Med.2012;27(4):1-10.
Visual Music after Cage: Robert Breer, expanded cinema and Stockhausen's Originals (1964)
Authors: Uroskie Andrew V.
Published: July 2012

Within William Seitz's 1961 exhibition The Art of Assemblage for the New York Museum of Modern Art, the question of framing – of art's exhibitionary situation within and against a given environment – had emerged as perhaps the major issue of postwar avant-garde practice. Beyond the familiar paintings of Johns and Rauschenberg, a strategy of radical juxtaposition in this time extended well beyond the use of new materials, to the very institutions of aesthetic exhibition and spectatorship. Perhaps the most significant example of this disciplinary juxtaposition can be found in the intermingling of the static and the temporal arts. Like many artists of the twentieth century, Robert Breer was fascinated by the aesthetic and philosophical character of movement. Trained as a painter, he turned to cinematic animation as a way of extending his inquiry into modernist abstraction. While the success of his initial Form Phases spurred what would be a lifelong commitment to film, Breer quickly grew frustrated with the kind of abstract animation that might be said to characterise the dominant tradition of visual music. Starting in 1955, his Image by Images inaugurated a radical new vision of hyperkinetic montage that would paradoxically function at the threshold of movement and stasis. As such, Breer's film ‘accompaniment’ to the 1964 production of Stockhausen's Originals has a curious status. While untethered from the musical performance, Breer's three-part ‘film performance’ extended Stockhausen's aesthetic and conceptual framework in rich and surprising ways. It might thus be understood as a ‘post-Cagean’ form of visual music, one in which the sonic and visual components function in a relation of autonomous complementarity within an overarching intermedia assemblage.
Ecological and sanitary characteristics of the Eurasian wild grapevine (Vitis vinifera L. ssp. sylvestris (Gmelin) Hegi) in Georgia (Caucasian region)
Authors: Ocete Rubio Rafael , Ocete Rubio Elvira , Ocete Pérez Carlos , Ángeles Pérez Izquierdo M. , Rustioni Laura , Failla Osvaldo , Chipashvili Ramaz , Maghradze David
Published: July 2012

This paper shows the results of the investigation on some ecological aspects and on the sanitary status of the wild Euroasiatic native grapevine (Vitis vinifera L. ssp. sylvestris (Gmelin) Hegi) in Georgia (South Caucasus). This taxon is seriously endangered by human activities such as forest cleaning and setting fires. Moreover, invasive Vitaceae of the North American origin, imported after phylloxera (Daktulosphaira vitifoliae Fitch) when vineyards were being replanted, increase the risk to lose these spontaneous vines. The survey includes collection of data on the population structure, the plant sex ratio, the main botanical supporters of the vines and the associated flora, the presence of invasive vines of the North American origin and the incidence of phytophagous arthropods and pathogens. The phytosanitary study showed that monophagous eriophyid mites and exotic fungal diseases, such as downy (Plasmopara viticola (Berkeley and Curtis) Berlease and de Toni) and powdery mildews (Erysiphe necator –(Schweinitz) Burrill), cause symptoms on all the observed populations. The absence of symptoms caused by phylloxera, root-knot nematodes and root rot is remarkable. However, the level of detected injuries caused by these parasitic organisms does not seem to be a real problem for the survival of the populations.
Link between microbial composition and carbon substrate-uptake preferences in a PHA-storing community
Authors: Albuquerque Maria G E , Carvalho Gilda , Kragelund Caroline , Silva Ana F , Barreto Crespo Maria T , Reis Maria A M , Nielsen Per H
Published: July 2012

The microbial community of a fermented molasses-fed sequencing batch reactor (SBR) operated under feast and famine conditions for production of polyhydroxyalkanoates (PHAs) was identified and quantified through a 16 S rRNA gene clone library and fluorescence in situ hybridization (FISH). The microbial enrichment was found to be composed of PHA-storing populations (84% of the microbial community), comprising members of the genera Azoarcus, Thauera and Paracoccus. The dominant PHA-storing populations ensured the high functional stability of the system (characterized by high PHA-storage efficiency, up to 60% PHA content). The fermented molasses contained primarily acetate, propionate, butyrate and valerate. The substrate preferences were determined by microautoradiography-FISH and differences in the substrate-uptake capabilities for the various probe-defined populations were found. The results showed that in the presence of multiple substrates, microbial populations specialized in different substrates were selected, thereby co-existing in the SBR by adapting to different niches. Azoarcus and Thauera, primarily consumed acetate and butyrate, respectively. Paracoccus consumed a broader range of substrates and had a higher cell-specific substrate uptake. The relative species composition and their substrate specialization were reflected in the substrate removal rates of different volatile fatty acids in the SBR reactor.
Mechanisms determining the fate of dispersed bacterial communities in new environments
Authors: Székely Anna J , Berga Mercè , Langenheder Silke
Published: July 2012

Recent work has shown that dispersal has an important role in shaping microbial communities. However, little is known about how dispersed bacteria cope with new environmental conditions and how they compete with local resident communities. To test this, we implemented two full-factorial transplant experiments with bacterial communities originating from two sources (freshwater or saline water), which were incubated, separately or in mixes, under both environmental conditions. Thus, we were able to separately test for the effects of the new environment with and without interactions with local communities. We determined community composition using 454-pyrosequencing of bacterial 16S rRNA to specifically target the active fraction of the communities, and measured several functional parameters. In absence of a local resident community, the net functional response was mainly affected by the environmental conditions, suggesting successful functional adaptation to the new environmental conditions. Community composition was influenced both by the source and the incubation environment, suggesting simultaneous effects of species sorting and functional plasticity. In presence of a local resident community, functional parameters were higher compared with those expected from proportional mixes of the unmixed communities in three out of four cases. This was accompanied by an increase in the relative abundance of generalists, suggesting that competitive interactions among local and immigrant taxa could explain the observed ‘functional overachievement’. In summary, our results suggest that environmental filtering, functional plasticity and competition are all important mechanisms influencing the fate of dispersed communities.
The nuclear factor κB inhibitor (E)-2-fluoro-4′-methoxystilbene inhibits firefly luciferase
Authors: Braeuning Albert , Vetter Silvia
Published: July 2012

Photinus pyralis (firefly) luciferase is widely used as a reporter system to monitor alterations in gene promoter and/or signalling pathway activities in vitro. The enzyme catalyses the formation of oxyluciferin from D-luciferin in an ATP-consuming reaction involving photon emission. The purpose of the present study was to characterize the luciferase-inhibiting potential of (E)-2-fluoro-4′-methoxystilbene, which is known as a potent inhibitor of the NF-κB (nuclear factor κB) signalling pathway that is used to modulate the NF-κB signalling pathway in vitro. Results show that (E)-2-fluoro-4′-methoxystilbene effectively inhibits firefly luciferase activity in cell lysates and living cells in a non-competitive manner with respect to the luciferase substrates D-luciferin and ATP. By contrast, the compound has no effect on Renilla and Gaussia luciferases. The mechanism of firefly luciferase inhibition by (E)-2-fluoro-4′-methoxystilbene, as well as its potency is comparable to its structure analogue resveratrol. The in vitro use of trans-stilbenes such as (E)-2-fluoro-4′-methoxystilbene or resveratrol compromises firefly luciferase reporter assays as well as ATP/luciferase-based cell viability assays.
The anaerobic biosynthesis of vitamin B12
Authors: Moore Simon J. , Warren Martin J.
Published: July 2012

Vitamin B12 (cobalamin) is a cobalt-containing modified tetrapyrrole that is an essential nutrient for higher animals. Its biosynthesis is restricted to certain bacteria and requires approximately 30 enzymatic steps for its complete de novo construction. Remarkably, two distinct biosynthetic pathways exist, which are termed the aerobic and anaerobic routes. The anaerobic pathway has yet to be fully characterized due to the inherent instability of its oxygen-sensitive intermediates. Bacillus megaterium, a bacterium previously used for the commercial production of cobalamin, has a complete anaerobic pathway and this organism is now being used to investigate the anaerobic B12 pathway through the application of recent advances in recombinant protein production. The present paper provides a summary of recent findings in the anaerobic pathway and future perspectives.
Engineering oxidoreductases: maquette proteins designed from scratch
Authors: Lichtenstein Bruce R. , Farid Tammer A. , Kodali Goutham , Solomon Lee A. , Anderson J.L. Ross , Sheehan Molly M. , Ennist Nathan M. , Fry Bryan A. , Chobot Sarah E. , Bialas Chris , Mancini Joshua A. , Armstrong Craig T. , Zhao Zhenyu , Esipova Tatiana V. , Snell David , Vinogradov Sergei A. , Discher Bohdana M. , Moser Christopher C. , Dutton P. Leslie
Published: July 2012

The study of natural enzymes is complicated by the fact that only the most recent evolutionary progression can be observed. In particular, natural oxidoreductases stand out as profoundly complex proteins in which the molecular roots of function, structure and biological integration are collectively intertwined and individually obscured. In the present paper, we describe our experimental approach that removes many of these often bewildering complexities to identify in simple terms the necessary and sufficient requirements for oxidoreductase function. Ours is a synthetic biology approach that focuses on from-scratch construction of protein maquettes designed principally to promote or suppress biologically relevant oxidations and reductions. The approach avoids mimicry and divorces the commonly made and almost certainly false ascription of atomistically detailed functionally unique roles to a particular protein primary sequence, to gain a new freedom to explore protein-based enzyme function. Maquette design and construction methods make use of iterative steps, retraceable when necessary, to successfully develop a protein family of sturdy and versatile single-chain three- and four-α-helical structural platforms readily expressible in bacteria. Internally, they prove malleable enough to incorporate in prescribed positions most natural redox cofactors and many more simplified synthetic analogues. External polarity, charge-patterning and chemical linkers direct maquettes to functional assembly in membranes, on nanostructured titania, and to organize on selected planar surfaces and materials. These protein maquettes engage in light harvesting and energy transfer, in photochemical charge separation and electron transfer, in stable dioxygen binding and in simple oxidative chemistry that is the basis of multi-electron oxidative and reductive catalysis.
Redox, haem and CO in enzymatic catalysis and regulation
Authors: Ragsdale Stephen W. , Yi Li , Bender Güneş , Gupta Nirupama , Kung Yan , Yan Lifen , Stich Troy A. , Doukov Tzanko , Leichert Lars , Jenkins Paul M. , Bianchetti Christopher M. , George Simon J. , Cramer Stephen P. , Britt R. David , Jakob Ursula , Martens Jeffrey R. , Phillips George N. , Drennan Catherine L.
Published: July 2012

The present paper describes general principles of redox catalysis and redox regulation in two diverse systems. The first is microbial metabolism of CO by the Wood–Ljungdahl pathway, which involves the conversion of CO or H2/CO2 into acetyl-CoA, which then serves as a source of ATP and cell carbon. The focus is on two enzymes that make and utilize CO, CODH (carbon monoxide dehydrogenase) and ACS (acetyl-CoA synthase). In this pathway, CODH converts CO2 into CO and ACS generates acetyl-CoA in a reaction involving Ni·CO, methyl-Ni and acetyl-Ni as catalytic intermediates. A 70 Å (1 Å=0.1 nm) channel guides CO, generated at the active site of CODH, to a CO ‘cage’ near the ACS active site to sequester this reactive species and assure its rapid availability to participate in a kinetically coupled reaction with an unstable Ni(I) state that was recently trapped by photolytic, rapid kinetic and spectroscopic studies. The present paper also describes studies of two haem-regulated systems that involve a principle of metabolic regulation interlinking redox, haem and CO. Recent studies with HO2 (haem oxygenase-2), a K+ ion channel (the BK channel) and a nuclear receptor (Rev-Erb) demonstrate that this mode of regulation involves a thiol–disulfide redox switch that regulates haem binding and that gas signalling molecules (CO and NO) modulate the effect of haem.
The late-time dynamics of the single-mode Rayleigh-Taylor instability
Authors: Ramaprabhu P. , Dimonte Guy , Woodward P. , Fryer C. , Rockefeller G. , Muthuraman K. , Lin P.-H. , Jayaraj J.
Published: July 2012

We report on numerical simulations of the detailed evolution of the single mode Rayleigh-Taylor [Lord Rayleigh, Scientific Papers II (Cambridge University Press, Cambridge, 1900), p. 200; G. I. Taylor, “The instability of liquid surfaces when accelerated in a direction perpendicular to their plane,” Proc. R. Soc. London, Ser. A 201, 192 (1950)10.1098/rspa.1950.0052; S. Chandrasekhar, Hydrodynamic and Hydromagnetic Stability (Oxford University Press, Oxford, 1961)] instability to late times and high aspect ratios. In contrast to established potential flow models that predict a terminal velocity and a constant Froude number at low Atwood numbers, we observe a complex sequence of events that can be summarized in four stages: I. Exponential growth of imposed perturbations, II. Saturation to terminal velocity, III. Reacceleration to a higher Froude number, and IV. Chaotic mixing. The observed reacceleration away from the Froude number predicted by potential flow theory is attributed to the appearance of secondary Kelvin–Helmholtz structures, and described with a modification to the potential flow model proposed by Betti and Sanz [R. Betti and J. Sanz, “Bubble acceleration in the ablative Rayleigh-Taylor instability,” Phys. Rev. Lett. 97, 205002 (2006)10.1103/PhysRevLett.97.205002]. The secondary KH instability is in turn sensitive to several parameters, and can be suppressed at large Atwood numbers, as well as viscosity (physical or numerical), with the bubble/spike velocity in each case reverting to the potential flow value. Our simulations delineate the change in dynamics of the primary and secondary instabilities due to changes in these flow parameters. When the flow is allowed to evolve to late times, further instability is observed, resulting in chaotic mixing which is quantified here. The increased atomic mixing due to small-scale structures results in a dramatic drop in the late-time Froude number. Spike behavior resembles bubbles at low A, while for large A, spikes approach free-fall – thus, the notion of a terminal velocity appears not to be applicable to spikes at any density difference. We expect the results to be relevant to turbulent mix models that are based on bubble growth and interaction.
Scalar fundamental measure theory for hard spheres in three dimensions: Application to hydrophobic solvation
Authors: Levesque Maximilien , Vuilleumier Rodolphe , Borgis Daniel
Published: July 2012

Hard-sphere mixtures provide one a solvable reference system that can be used to improve the density functional theory of realistic molecular fluids. We show how the Kierlik–Rosinberg's scalar version of the fundamental measure density functional theory of hard spheres [E. Kierlik and M. L. Rosinberg, Phys. Rev. A 42, 3382 (1990)10.1103/PhysRevA.42.3382], which presents computational advantages with respect to the original Rosenfeld's vectorial formulation or its extensions, can be implemented and minimized in three dimensions to describe fluid mixtures in complex environments. This implementation is used as a basis for defining a molecular density functional theory of water around molecular hydrophobic solutes of arbitrary shape.
Development of polarization-controlled multi-pass Thomson scattering system in the GAMMA 10 tandem mirror
Authors: Yoshikawa M. , Yasuhara R. , Morimoto M. , Shima Y. , Kohagura J. , Sakamoto M. , Nakashima Y. , Imai T. , Yamada I. , Kawahata K. , Funaba H. , Minami T.
Published: July 2012

In the GAMMA 10 tandem mirror, the typical electron density is comparable to that of the peripheral plasma of torus-type fusion devices. Therefore, an effective method to increase Thomson scattering (TS) signals is required in order to improve signal quality. In GAMMA 10, the yttrium-aluminum-garnet (YAG)-TS system comprises a laser, incident optics, light collection optics, signal detection electronics, and a data recording system. We have been developing a multi-pass TS method for a polarization-based system based on the GAMMA 10 YAG TS. To evaluate the effectiveness of the polarization-based configuration, the multi-pass system was installed in the GAMMA 10 YAG-TS system, which is capable of double-pass scattering. We carried out a Rayleigh scattering experiment and applied this double-pass scattering system to the GAMMA 10 plasma. The integrated scattering signal was made about twice as large by the double-pass system.
Dynamics of intense laser propagation in underdense plasma: Polarization dependence
Authors: Singh D. K. , Davies J. R. , Sarri G. , Fiuza F. , Silva L. O.
Published: July 2012

We present a comprehensive numerical study of the dynamics of an intense laser pulse as it propagates through an underdense plasma in two and three dimensions. By varying the background plasma density and the polarization of the laser beam, significant differences are found in terms of energy transport and dissipation, in agreement with recently reported experimental results. Below the threshold for relativistic self-focusing, the plasma and laser dynamics are observed to be substantially insensitive to the initial laser polarization, since laser transport is dominated by ponderomotive effects. Above this threshold, relativistic effects become important, and laser energy is dissipated either by plasma heating (p-polarization) or by trapping of electromagnetic energy into plasma cavities (s-polarization) or by a combination of both (circular polarization). Besides the fundamental interest of this study, the results presented are relevant to applications such as plasma-based accelerators, x-ray lasers, and fast-ignition inertial confinement fusion.
Band offset measurements of the GaN/dielectric interfaces
Authors: Coan Mary R. , Woo Jung Hwan , Johnson Derek , Gatabi Iman Rezanezhad , Harris H. Rusty
Published: July 2012

X-ray and ultra violet photoelectron spectroscopy are used to observe the interface electronic states at the GaN (0001) and high-κ dielectric interfaces. The GaN is aqueous HCl cleaned prior to atomic layer deposition of Al2O3 and HfO2, then followed by a post deposition anneal. The GaN/HfO2 and GaN/Al2O3 interfaces exhibited dipoles of 1.6 eV and 0.4 eV, respectively. It is found that the formation of an interfacial layer at the GaN/HfO2 interface is the primary cause of the larger dipole.
Passive load alleviation bi-stable morphing concept
Authors: Arrieta A. F. , Bilgen O. , Friswell M. I. , Hagedorn P.
Published: July 2012

In wind turbines, large loads caused by fluid structure interaction leading to fatigue failure and added robustness to withstand high bending stresses on the root of blades constitute important design bottlenecks. Implementation of morphing offers a potential solution for such challenges in wind turbine blades. In this letter, a passive load alleviating bi-stable morphing concept is proposed. A bi-stable specimen designed to have different stiffness and dynamic response characteristics on each stable state is devised as a compliant structure. Passive alleviation mechanisms require no active components to achieve the load alleviation objective, resulting in lighter and simpler designs in comparison to actively morphed solutions.
Neutronics experiments for uncertainty assessment of tritium breeding in HCPB and HCLL blanket mock-ups irradiated with 14 MeV neutrons
Authors: Batistoni P. , Angelone M. , Fischer U. , Klix A. , Kodeli I. , Leichtle D. , Pillon M. , Pohorecki W. , Villari R.
Published: July 2012

Two neutronics experiments have been carried out at 14 MeV neutron sources on mock-ups of the helium cooled pebble bed (HCBP) and the helium cooled lithium lead (HCLL) variants of ITER test blanket modules (TBMs). These experiments have provided an experimental validation of the calculations of the tritium production rate (TPR) in the two blanket concepts and an assessment of the uncertainties due to the uncertainties on nuclear data. This paper provides a brief summary of the HCPB experiment and then focuses in particular on the final results of the HCLL experiment. The TPR has been measured in the HCLL mock-up irradiated for long times at the Frascati 14 MeV Neutron Generator (FNG). Redundant and well-assessed experimental techniques have been used to measure the TPR by different teams for inter-comparison. Measurements of the neutron and gamma-ray spectra have also been performed. The analysis of the experiment, carried out by the MCNP code with FENDL-2.1 and JEFF-3.1.1 nuclear data libraries, and also including sensitivity/uncertainty analysis, shows good agreement between measurements and calculations, within the total uncertainty of 5.9% at 1σ level.
Effect of Interaction Potential on Laser-assisted e-Ar Scattering
Authors: Wang Xiao-fei , Hu Qiu-bo , Sun Jing-feng
Published: July 2012

The interaction potentials between electron and atom play an important role in electron-atom scattering. Using three potential models, the absolute differential cross section has been calculated by the second Born approximation theory. Results show that these model potentials are successful in the laser-assisted e-Ar scattering system. The influence of static potential, exchange potential and polarization potential on the absolute differential cross section is also analyzed and discussed.
Hydrogenated Graphene as Metal-free Catalyst for Fenton-like Reaction
Authors: Zhao Yi , Chen Wu-feng , Yuan Cheng-fei , Zhu Zi-ye , Yan Li-feng
Published: July 2012

Carbonaceous catalysts are potential alternatives to metal catalysts. Graphene has been paid much attention for its high surface area and light weight. Here, hydrogenated graphene has been prepared by a simple gamma ray irradiation of graphene oxide aqueous suspension at room temperature. Transmission electron microscopic, element analysis, X-ray photoelectron spectroscopy, and UV-Vis spectrophotometer studies verified the hydrogenation of graphene. The as-prepared hydrogenated graphene can be used as a metal-free carbonaceous catalyst for the Fenton-like degradation of organic dye in water.