bluuebunny/crossref_metadata_2025 huggingface dataset:
Triggering sporulation in Bacillus subtilis with artificial two‐component systems reveals the importance of proper Spo0A activation dynamics
Authors: Vishnoi Monika , Narula Jatin , Devi Seram Nganbiton , Dao Hoang‐Anh , Igoshin Oleg A. , Fujita Masaya
Published: August 2013

Sporulation initiation in Bacillus subtilis is controlled by the phosphorylated form of the master regulator Spo0A which controls transcription of a multitude of sporulation genes. In this study, we investigated the importance of temporal dynamics of phosphorylated Spo0A (Spo0A∼P) accumulation by rewiring the network controlling its phosphorylation. We showed that simultaneous induction of KinC, a kinase that can directly phosphorylate Spo0A, and Spo0A itself from separately controlled inducible promoters can efficiently trigger sporulation even under nutrient rich conditions. However, the sporulation efficiency in this artificial two‐component system was significantly impaired when KinC and/or Spo0A induction was too high. Using mathematical modelling, we showed that gradual accumulation of Spo0A∼P is essential for the proper temporal order of the Spo0A regulon expression, and that reduction in sporulation efficiency results from the reversal of that order. These insights led us to identify premature repression of DivIVA as one possible explanation for the adverse effects of accelerated accumulation of Spo0A∼P on sporulation. Moreover, we found that positive feedback resulting from autoregulation of the native spo0A promoter leads to robust control of Spo0A∼P accumulation kinetics. Thus we propose that a major function of the conserved architecture of the sporulation network is controlling Spo0A activation dynamics.
Induced ectopic expression of HigB toxin in Mycobacterium tuberculosis results in growth inhibition, reduced abundance of a subset of mRNAs and cleavage of tmRNA
Authors: Schuessler Dorothée L. , Cortes Teresa , Fivian‐Hughes Amanda S. , Lougheed Kathryn E. A. , Harvey Evelyn , Buxton Roger S. , Davis Elaine O. , Young Douglas B.
Published: August 2013

In Mycobacterium tuberculosis, the genes Rv1954A–Rv1957 form an operon that includes Rv1955 and Rv1956 which encode the HigB toxin and the HigA antitoxin respectively. We are interested in the role and regulation of this operon, since toxin–antitoxin systems have been suggested to play a part in the formation of persister cells in mycobacteria. To investigate the function of the higBA locus, effects of toxin expression on mycobacterial growth and transcript levels were assessed in M. tuberculosis H37Rv wild type and in an operon deletion background. We show that expression of HigB toxin in the absence of HigA antitoxin arrests growth and causes cell death in M. tuberculosis. We demonstrate HigB expression to reduce the abundance of IdeR and Zur regulated mRNAs and to cleave tmRNA in M. tuberculosis, Escherichia coli and Mycobacterium smegmatis. This study provides the first identification of possible target transcripts of HigB in M. tuberculosis.
Carbohydrate‐binding agents act as potent trypanocidals that elicit modifications in VSG glycosylation and reduced virulence in Trypanosoma brucei
Authors: Castillo‐Acosta Víctor M. , Vidal Antonio E. , Ruiz‐Pérez Luis M. , Van Damme Els J. M. , Igarashi Yasuhiro , Balzarini Jan , González‐Pacanowska Dolores
Published: August 2013

The surface of Trypanosoma brucei is covered by a dense coat of glycosylphosphatidylinositol‐anchored glycoproteins. The major component is the variant surface glycoprotein (VSG) which is glycosylated by both paucimannose and oligomannose N‐glycans. Surface glycans are poorly accessible and killing mediated by peptide lectin–VSG complexes is hindered by active endocytosis. However, contrary to previous observations, here we show that high‐affinity carbohydrate binding agents bind to surface glycoproteins and abrogate growth of T. brucei bloodstream forms. Specifically, binding of the mannose‐specific Hippeastrum hybrid agglutinin (HHA) resulted in profound perturbations in endocytosis and parasite lysis. Prolonged exposure to HHA led to the loss of triantennary oligomannose structures in surface glycoproteins as a result of genetic rearrangements that abolished expression of the oligosaccharyltransferase TbSTT3B gene and yielded novel chimeric enzymes. Mutant parasites exhibited markedly reduced infectivity thus demonstrating the importance of specific glycosylation patterns in parasite virulence.
Oligomerization of the chitin synthase Chs3 is monitored at the Golgi and affects its endocytic recycling
Authors: Sacristan Carlos , Manzano‐Lopez Javier , Reyes Abigail , Spang Anne , Muñiz Manuel , Roncero Cesar
Published: August 2013

Chs3, the catalytic subunit of chitin synthase III in Saccharomyces cerevisiae, is a complex polytopic membrane protein whose plasma membrane expression is tightly controlled: export from the ER requires interaction with Chs7; exit from the Golgi is dependent on the exomer complex, and precise bud neck localization relies on endocytosis. Moreover, Chs3 is efficiently recycled from endosomes to the TGN in an AP‐1‐dependent manner. Here we show that the export of Chs3 requires the cargo receptor Erv14, in a step that is independent of Chs7. Chs3 oligomerized in the ER through its N‐terminal cytosolic region. However, the truncated Δ126Chs3 was still exported by Erv14, but was sent back from the Golgi to the ER in a COPI‐ and Rer1‐dependent manner. A subset of the oligomerization‐deficient Chs3 proteins evaded Golgi quality control and reached the plasma membrane, where they were enzymatically active but poorly endocytosed. This resulted in high CSIII levels, but calcofluor white resistance, explained by the reduced intercalation of calcofluor white between nascent chitin fibres. Our data show that the oligomerization of Chs3 through its N‐terminus is essential for proper protein trafficking and chitin synthesis and is therefore monitored intracellularly.
The crystal structure of the cell division amidase AmiC reveals the fold of the AMIN domain, a new peptidoglycan binding domain
Authors: Rocaboy Mathieu , Herman Raphael , Sauvage Eric , Remaut Han , Moonens Kristof , Terrak Mohammed , Charlier Paulette , Kerff Frederic
Published: August 2013

Binary fission is the ultimate step of the prokaryotic cell cycle. In Gram‐negative bacteria like Escherichia coli, this step implies the invagination of three biological layers (cytoplasmic membrane, peptidoglycan and outer membrane), biosynthesis of the new poles and eventually, daughter cells separation. The latter requires the coordinated action of the N‐acetylmuramyl‐L‐alanine amidases AmiA/B/C and their LytM activators EnvC and NlpD to cleave the septal peptidoglycan. We present here the 2.5 Å crystal structure of AmiC which includes the first report of an AMIN domain structure, a β‐sandwich of two symmetrical four‐stranded β‐sheets exposing highly conserved motifs on the two outer faces. We show that this N‐terminal domain, involved in the localization of AmiC at the division site, is a new peptidoglycan‐binding domain. The C‐terminal catalytic domain shows an auto‐inhibitory alpha helix obstructing the active site. AmiC lacking this helix exhibits by itself an activity comparable to that of the wild type AmiC activated by NlpD. We also demonstrate the interaction between AmiC and NlpD by microscale thermophoresis and confirm the importance of the active site blocking alpha helix in the regulation of the amidase activity.
Cytomegalovirus & Epstein Barr Virus serostatus as a predictor of the long‐term outcome of kidney transplantation
Authors: Le Page Amelia K , Mackie Fiona E , McTaggart Steven J , Kennedy Sean E
Published: August 2013

Aim

Cytomegalovirus (CMV) and Epstein Barr Virus (EBV) disease and asymptomatic infection have been associated with poor outcomes in kidney transplantation. Recipients who acquire primary infection through transplantation from a seropositive donor may be at particular risk of complications. The primary aim of this study was to evaluate the relationship between donor/recipient (D/R) CMV and EBV serostatus pretransplant and allograft and patient survival in a large cohort of kidney transplant recipients.

Methods

Data were obtained from the Australian and New Zealand Dialysis and Transplant Registry and the Australian and New Zealand Organ Donation Registry on 4516 first deceased donor kidney transplants performed between 1998 and 2010. Graft and patient survival were analysed using the Kaplan–Meier method.

Results

Pretransplant CMV D/R serostatus was available for the whole cohort, with EBV D/R serostatus available for 2566 transplants (56.8%). Serostatus for both viruses was significantly associated with donor and recipient age and recipient smoking status. For both viruses the majority of transplants were in a D+/R+ serostatus setting: 45.3% for CMV and 77.9% for EBV. D/R serostatus for either virus did not have a significant effect on graft or patient survival.

Conclusion

We conclude that in the current era of viral prophylaxis and surveillance, long‐term outcome for the kidney transplant population is unaffected by D/R CMV and EBV serostatus.
Assessing the Applicability of Singlet Oxygen Photosensitizers in Leaf Studies
Authors: Kovács László , Ayaydin Ferhan , Kálai Tamás , Tandori Júlia , Kós Péter B. , Hideg Éva
Published: August 2013

Singlet oxygen (1O2) is of special interest in plant stress physiology. Studies focused on internal, chlorophyll‐mediated production are often complemented with the use of artificial 1O2 photosensitizers. Here, we report a comparative study on the effects of Rose Bengal (RB), Methylene Violet (MVI), Neutral Red (NR) and Indigo Carmine (IC). These were infiltrated into tobacco leaves at concentrations generating the same fluxes of 1O2 in solution. Following green light‐induced 1O2 production from these dyes, leaf photosynthesis was characterized by Photosystem (PS) II and PSI electron transport and oxidative damage was monitored as degradation of D1, a PSII core protein. Cellular localizations were identified on the basis of the dyes’ fluorescence using confocal laser scanning microscopy. We found that RB and NR were both localized in chloroplasts but the latter had very little effect, probably due to its pH‐dependent photosensitizing. Both RB and intracellular, nonplastid MVI decreased PSII electron transport, but the effect of RB was stronger than that of MVI and only RB was capable of damaging the D1 protein. Intercellularly localized IC had no significant effect. Our results also suggest caution when using RB as photosensitizer because it affects PSII electron transport.
Increased symplasmic permeability in barley root epidermal cells correlates with defects in root hair development
Authors: Marzec M. , Muszynska A. , Melzer M. , Sas‐Nowosielska H. , Kurczynska E. U.
Published: August 2013

It is well known that the process of plant cell differentiation depends on the symplasmic isolation of cells. Before starting the differentiation programme, the individual cell or group of cells should restrict symplasmic communication with neighbouring cells. We tested the symplasmic communication between epidermal cells in the different root zones of parental barley plants Hordeum vulgare L., cv. ‘Karat’ with normal root hair development, and two root hairless mutants (rhl1.a and rhl1.b). The results clearly show that symplasmic communication was limited during root hair differentiation in the parental variety, whereas in both root hairless mutants epidermal cells were still symplasmically connected in the corresponding root zone. This paper is the first report on the role of symplasmic isolation in barley root cell differentiation, and additionally shows that a disturbance in the restriction of symplasmic communication is present in root hairless mutants.
Outsourcing Competition and Information Sharing with Asymmetrically Informed Suppliers
Authors: Zhao Xia , Xue Ling , Zhang Fuqiang
Published: August 2013

This paper studies an outsourcing problem where two service providers (suppliers) compete for the service contract from a client. The suppliers face uncertain cost for providing the service because they do not have perfect information about the client's type. The suppliers receive differential private signals about the client type and thus compete under asymmetric information. We first characterize the equilibrium of the supplier competition. Then we investigate two of the client's information sharing decisions. It is shown that less information asymmetry between the suppliers may dampen their competition. Therefore, the client does not necessarily have the incentive to reduce information asymmetry between the suppliers. We characterize the conditions under which leveling the informational ground is beneficial to the client. We also find that under the presence of information asymmetry (e.g., when the suppliers have different learning abilities), sharing more information with both suppliers may enhance the advantage of one supplier over the other and at the same time increase the upper bound of the suppliers' quotes in equilibrium. Consequently, the suppliers compete less aggressively and the client's payoff decreases in the amount of shared information. The findings from this study provide useful managerial implications on information management for outsourcing firms.
Supplier Selection for Framework Agreements in Humanitarian Relief
Authors: Balcik Burcu , Ak Deniz
Published: August 2013

In this study, we consider the supplier selection problem of a relief organization that wants to establish framework agreements (FAs) with a number of suppliers to ensure quick and cost‐effective procurement of relief supplies in responding to sudden‐onset disasters. Motivated by the FAs in relief practice, we focus on a quantity flexibility contract in which the relief organization commits to purchase a minimum total quantity from each framework supplier over a fixed agreement horizon, and, in return, the suppliers reserve capacity for the organization and promise to deliver items according to pre‐specified agreement terms. Due to the uncertainties in demand locations and amounts, it may be challenging for relief organizations to assess candidate suppliers and the offered agreement terms. We use a scenario‐based approach to represent demand uncertainty and develop a stochastic programming model that selects framework suppliers to minimize expected procurement and agreement costs while meeting service requirements. We perform numerical experiments to understand the implications of agreement terms in different settings. The results show that supplier selection decisions and costs are generally more sensitive to the changes in agreement terms in settings with high‐impact disasters. Finally, we illustrate the applicability of our model on a case study.
Vehicle Procurement Policy for Humanitarian Development Programs
Authors: Eftekhar Mahyar , Masini Andrea , Robotis Andreas , Van Wassenhove Luk N.
Published: August 2013

This article aims to identify optimal vehicle procurement policies for organizations engaged in humanitarian development programs and to derive general insights on the characteristics of these policies. Toward that end, we follow an inductive approach. First, we study the operations of the International Committee of the Red Cross (ICRC) in three representative countries: Sudan, Afghanistan, and Ethiopia. Using a linear programming (LP) model primed with field data provided by the ICRC, we calculate the optimal vehicle fleet size and compare it with the policies actually implemented. Second, drawing from results of the LP model, we develop a stylized quadratic control model and use it to characterize the general structure of the optimal policy under different demand scenarios and operational constraints. After demonstrating that the results of the control model are consistent with those of the LP model in the specific context analyzed, we discuss the optimal policies and the applicability of the former as a practical tool for strategic asset planning.
Assessing Trade‐offs among Multiple Objectives for Humanitarian Aid Delivery Using Expert Preferences
Authors: Gralla Erica , Goentzel Jarrod , Fine Charles
Published: August 2013

Humanitarian aid agencies deliver emergency supplies and services to people affected by disasters. Scholars and practitioners have developed modeling approaches to support aid delivery planning, but they have used objective functions with little validation as to the trade‐offs among the multiple goals of aid delivery. We develop a method to value the performance of aid delivery plans based on expert preferences over five key attributes: the amount of cargo delivered, the prioritization of aid by commodity type, the prioritization of aid by delivery location, the speed of delivery, and the operational cost. Through a conjoint analysis survey, we measure the preferences of 18 experienced humanitarian logisticians. The survey results quantify the importance of each attribute and enable the development of a piecewise linear utility function that can be used as an objective function in optimization models. The results show that the amount of cargo delivered is the most valued objective and cost the least important. In addition, experts prioritize more vulnerable communities and more critical commodities, but not to the exclusion of others. With these insights and the experts’ utility functions, better humanitarian objective functions can be developed to enable better aid delivery in emergency response.
The Transgenerational Consequences of Discrimination on African‐American Health Outcomes
Authors: Goosby Bridget J. , Heidbrink Chelsea
Published: August 2013

Disparities in African American health remain pervasive and persist ransgenerationally. There is a growing consensus that both structural and interpersonal racial discrimination are key mechanisms affecting African American health. The Biopsychosocial Model of Racism as a Stressor posits that the persistent stress of experiencing discrimination take a physical toll on the health of African Americans and is ultimately manifested in the onset of illness. However, the degree to which the health consequences of racism and discrimination can be passed down from one generation to the next is an important avenue of exploration. In this review, we discuss and link literature across disciplines demonstrating the harmful impact of racism on African American physical health and the health of their offspring.
Gender and Multigenerational Global Human Development
Authors: Reid Julie A. , Shams Tahseen
Published: August 2013

In the context of a growing campaign to focus more international development efforts on women and girls, this article presents a pathways model of multigenerational global human development through an examination of gender and women as agents of development in the context of motherhood. As the vast majority of the world's women are mothers, issues related to motherhood are fundamental to addressing gender and development. Based on the United Nations' concept of human development and a review of the literature, we explore how women are uniquely effective development agents in that increases in women's access to income, education, and health often have higher potential payoffs compared with men in terms of the next generation and beyond. A human development paradigm that does not fully include women is both an injustice to half of the world's population and a missed opportunity for maximizing human development for both men and women in generations to come. Gender and development policies must consider the enhancement of human capacities for long‐term improved quality of life, and they must address structural barriers to equality to not only allow women more opportunities in the public sphere but also to transform gender relations in the domestic sphere.
‘Universal’ spray droplet adhesion model – accounting for hairy leaves
Authors: Nairn J J , Forster W A , van Leeuwen R M
Published: August 2013

The adhesion of a spray droplet upon initial contact with a leaf surface is extremely important to spray efficacy and is dependent on dynamic interactions between droplets (formulation, size, velocity) and leaf (micro‐topography, surface chemistry, veininess, hairiness and orientation). A ‘universal’ spray droplet adhesion model has previously been developed, using 50% aqueous acetone contact angles as a measure of leaf surface properties; this model satisfactorily predicts initial adhesion over a range of formulation surface tensions, droplet sizes and velocities. However, it failed to fit data from hairier leaves. This study investigates initial spray droplet adhesion on hairy leaves. Two categories of hairy leaves were identified by how the droplets penetrate the leaf hairs, Wenzel (hairy) and Cassie–Baxter (super hairy). For the Wenzel‐type, a simple constant accounted for the increased droplet shatter caused by the hairs. For the Cassie–Baxter‐type, a cushioning factor was introduced to account for the absorption of kinetic energy at impact by the hair mat. The cushioning factor was estimated by measuring the relative height of the hair mat. By including these two parameters, the new model successfully predicted the mean adhesion of non‐hairy, hairy and super‐hairy plants (R2 = 0.96). This model and the underlying principles determining hairy leaf adhesion developed in this article will help develop spray formulations effective at targeting hairy‐leaved weed and crop species.
Detrimental dermal wound healing: What can we learn from the oral mucosa?
Authors: Glim Judith E. , van Egmond Marjolein , Niessen Frank B. , Everts Vincent , Beelen Robert H. J.
Published: August 2013

Wounds in adults are frequently accompanied by scar formation. This scar can become fibrotic due to an imbalance between extracellular matrix (ECM) synthesis and ECM degradation. Oral mucosal wounds, however, heal in an accelerated fashion, displaying minimal scar formation. The exact mechanisms of scarless oral healing are yet to be revealed. This review highlights possible mechanisms involved in the difference between scar‐forming dermal vs. scarless oral mucosal wound healing. Differences were found in expression of ECM components, such as procollagen I and tenascin‐C. Oral wounds contained fewer immune mediators, blood vessels, and profibrotic mediators but had more bone marrow–derived cells, a higher reepithelialization rate, and faster proliferation of fibroblasts compared with dermal wounds. These results form a basis for further research that should be focused on the relations among ECM, immune cells, growth factors, and fibroblast phenotypes, as understanding scarless oral mucosal healing may ultimately lead to novel therapeutic strategies to prevent fibrotic scars.
Development of a novel ex vivo porcine skin explant model for the assessment of mature bacterial biofilms
Authors: Yang Qingping , Phillips Priscilla L. , Sampson Edith M. , Progulske‐Fox Ann , Jin Shouguang , Antonelli Patrick , Schultz Gregory S.
Published: August 2013

Bacterial biofilms have been proposed to be a major factor contributing to the failure of chronic wounds to heal because of their increased tolerance to antimicrobial agents and the prolonged inflammation they cause. Phenotypic characteristics of bacterial biofilms vary depending on the substratum to which they attach, the nutritional environment, and the microorganisms within the biofilm community. To develop an ex vivo biofilm model that more closely mimics biofilms in chronic skin wounds, we developed an optimal procedure to grow mature biofilms on a central partial‐thickness wound in 12‐mm porcine skin explants. Chlorine gas produced optimal sterilization of explants while preserving histological properties of the epidermis and dermis. Pseudomonas aeruginosa and Staphylococcus aureus developed mature biofilms after 3 days that had dramatically increased tolerance to gentamicin and oxacillin (∼100× and 8,000× minimal inhibitory concentration, respectively) and to sodium hypochlorite (0.6% active chlorine). Scanning electron microscopy and confocal microscopy verified extensive exopolymeric biofilm structures on the explants. Despite a significant delay, a ΔlasI quorum‐sensing mutant of P. aeruginosa developed biofilm as antibiotic‐tolerant as wild‐type after 3 days. This ex vivo model simulates growth of biofilms on skin wounds and provides an accurate model to assess effects of antimicrobial agents on mature biofilms.
Effects of systemic pretreatment with CpG oligodeoxynucleotides on skin wound healing in mice
Authors: Hergert Bettina , Grambow Eberhard , Butschkau Antje , Vollmar Brigitte
Published: August 2013

Unmethylated CpG oligodeoxynucleotides (ODN) bind to the Toll‐like receptor 9, thus stimulating the immune system. To study the effects of systemic pretreatment with CpG ODN on dermal regeneration, C57BL6/J Tyr mice were treated with CpG or control ODN 6 days prior to implantation of a dorsal skinfold chamber and skin wounding. Wound epithelialization was analyzed by planimetric microscopy. On day 18, wound tissues were taken for (immuno)histochemical staining. CpG ODN increased epithelialization compared with control ODN treatment. Histological analysis revealed reduced capillary density, reduced wound cellularity, and reduced numbers of infiltrating leukocytes, as well as reduced F4/80‐positive macrophages, but increased numbers of RELM‐α‐positive M2 macrophages after CpG ODN treatment, reflecting a better quality of wound healing on day 18 compared with control ODN treatment. Reverse transcription‐polymerase chain reaction analysis of Toll‐like receptor 9 showed the receptor expression on both fibroblasts and keratinocytes. Fibroblasts showed an increase of migration upon increasing dosages of CpG and not control ODN, reaching ∼50% of the response of basic fibroblast growth factor‐exposed cells. Keratinocytes dose‐dependently responded to both CpG and control ODN up to values found in keratinocyte growth factor‐exposed cells. In summary, CpG ODN support late tissue‐remodeling processes that contribute to resolution of inflammation and solid wounds during skin regeneration.
High bacterial load in negative pressure wound therapy (NPWT) foams used in the treatment of chronic wounds
Authors: Yusuf Erlangga , Jordan Xavier , Clauss Martin , Borens Olivier , Mäder Mark , Trampuz Andrej
Published: August 2013

No earlier study has investigated the microbiology of negative pressure wound therapy (NPWT) foam using a standardized manner. The purpose of this study is to investigate the bacterial load and microbiological dynamics in NPWT foam removed from chronic wounds (>3 months). To determine the bacterial load, a standardized size of the removed NPWT foam was sonicated. The resulting sonication fluid was cultured, and the colony‐forming units (CFU) of each species were enumerated. Sixty‐eight foams from 17 patients (mean age 63 years, 71% males) were investigated. In 65 (97%) foams, ≥ 1 and in 37 (54%) ≥2 bacterial types were found. The bacterial load remained high during NPWT treatment, ranging from 104 to 106 CFU/ml. In three patients (27%), additional type of bacteria was found in subsequent foam cultures. The mean bacterial count ± standard deviation was higher in polyvinyl alcohol foam (6.1 ± 0.5 CFU/ml) than in polyurethane (5.5 ± 0.8 CFU/ml) (p = 0.02). The mean of log of sum of CFU/ml in foam from 125 mmHg (5.5 ± 0.8) was lower than in foam from 100 mmHg pressure (5.9 ± 0.5) (p = 0.01). Concluding, bacterial load remains high in NPWT foam, and routine changing does not reduce the load.
Evolution of sputtered tungsten coatings at high temperature
Authors: Stelmakh Veronika , Rinnerbauer Veronika , Joannopoulos John D. , Soljačić Marin , Celanovic Ivan , Senkevich Jay J. , Tucker Charles , Ives Thomas , Shrader Ronney
Published: August 2013

Sputtered tungsten (W) coatings were investigated as potential high temperature nanophotonic material to replace bulk refractory metal substrates. Of particular interest are materials and coatings for thermophotovoltaic high-temperature energy conversion applications. For such applications, high reflectance of the substrate in the infrared wavelength range is critical in order to reduce losses due to waste heat. Therefore, the reflectance of the sputtered W coatings was characterized and compared at different temperatures. In addition, the microstructural evolution of sputtered W coatings (1 and 5 μm thick) was investigated as a function of anneal temperature from room temperature to 1000 °C. Using in situ x-ray diffraction analysis, the microstrain in the two samples was quantified, ranging from 0.33% to 0.18% for the 1 μm sample and 0.26% to 0.20% for the 5 μm sample, decreasing as the temperature increased. The grain growth could not be as clearly quantified due to the dominating presence of microstrain in both samples but was in the order of 20 to 80 nm for the 1 μm sample and 50 to 100 nm for the 5 μm sample, as deposited. Finally, the 5 μm thick layer was found to be rougher than the 1 μm thick layer, with a lower reflectance at all wavelengths. However, after annealing the 5 μm sample at 900 °C for 1 h, its reflectance exceeded that of the 1 μm sample and approached that of bulk W found in literature. Overall, the results of this study suggest that thick coatings are a promising alternative to bulk substrates as a low cost, easily integrated platform for nanostructured devices for high-temperature applications, if the problem of delamination at high temperature can be overcome.
Feasibility of a high-powered carbon nanotube thin-film loudspeaker
Authors: Barnard Andrew R. , Jenkins David M. , Brungart Timothy A. , McDevitt Timothy M. , Kline Brian L.
Published: August 2013

The thermophone, conceived in 1917 by Arnold and Crandall, was a unique thermoacoustic loudspeaker. The high heat capacity per unit area (HCPUA) of thin-film materials at that time limited the usefulness of thermophones. Recently, researchers of carbon nanotubes (CNTs) have developed techniques to create a super-aligned thin-film of multi-walled CNTs, possessing extremely low HCPUA. This paper will discuss CNT thin-film loudspeaker theory as well as some initial investigations into the feasibility of a high-powered audio CNT speaker. The advantages of such a loudspeaker include: Ultra-lightweight, compact, no moving parts, low cost, and independence from expensive rare-earth materials.
Active Atmosphere-Ecosystem Exchange of the Vast Majority of Detected Volatile Organic Compounds
Authors: Park J.-H. , Goldstein A. H. , Timkovsky J. , Fares S. , Weber R. , Karlik J. , Holzinger R.
Published: August 2013

Two-Way Street

Most studies of volatile organic compounds (VOCs) found in the atmosphere, which play important roles in atmospheric chemistry, have concentrated on dominant species such as isoprene. There are thousands of other classes of VOCs, and how they are exchanged between the biosphere and the atmosphere is unclear.

Park
et al.

(p.
643
) measured the fluxes of more than 500 types of VOCs using a highly sensitive type of mass spectrometry and an absolute value eddy covariance method. The majority of these species were actively exchanged between the atmosphere and the biosphere, with more than a quarter showing net deposition. These results should help to improve air quality and global climate models, and strengthen our understanding of atmospheric VOC chemistry.
Sequence-Controlled Polymers
Authors: Lutz Jean-François , Ouchi Makoto , Liu David R. , Sawamoto Mitsuo
Published: August 2013

Background

During the last few decades, progress has been made in manipulating the architecture of synthetic polymer materials. However, the primary structure—that is, the sequential arrangement of monomer units in a polymer chain—is generally poorly controlled in synthetic macromolecules. Common synthetic polymers are usually homopolymers, made of the same monomer unit, or copolymers with simple chain microstructures, such as random or block copolymers. These polymers are used in many areas but do not have the structural and functional complexity of sequence-defined biopolymers, such as nucleic acids or proteins. Indeed, monomer sequence regulation plays a key role in biology and is a prerequisite for crucial features of life, such as heredity, self-replication, complex self-assembly, and molecular recognition. In this context, developing synthetic polymers containing controlled monomer sequences is an important area for research.

Advances

Various synthetic methods for controlling monomer sequences in polymers have been identified, and two major trends in the field of sequence-controlled polymers have emerged. Some approaches use biological concepts that have been optimized by nature for sequence regulation. For instance, DNA templates, enzymes, or even living organisms can be used to prepare sequence-defined polymers. These natural mechanisms can be adapted to tolerate nonnatural monomers. The other trend is the preparation of sequence-controlled polymers by synthetic chemistry. In the most popular approach, monomer units are attached one by one to a support, which is an efficient method but demanding in practice. Recently, some strategies have been proposed for controlling sequences in chain-growth and step-growth polymerizations. These mechanisms usually allow fast and large-scale synthesis of polymers. Specific kinetics and particular catalytic or template conditions allow sequence regulation in these processes.

Outlook

The possibility of controlling monomer sequences in synthetic macromolecules has many scientific and technological implications. Information can be controlled at the molecular level in synthetic polymer chains. This opens up interesting perspectives for the field of data storage. In addition, having power over monomer sequences could mean structural control of the resulting polymer, as it strongly influences macromolecular folding and self-assembly. For instance, functional synthetic assemblies that mimic the properties of globular proteins, such as enzymes and transporters, can be foreseen. Moreover, monomer sequence control influences some macroscopic properties. For example, bulk properties such as conductivity, rigidity, elasticity, or biodegradability can be finely tuned in sequence-controlled polymers. The behavior of polymers in solution, particularly in water, is also strongly dependent on monomer sequences. Thus, sequence regulation may enable a more effective control of structure-property relations in tomorrow’s polymer materials.
Social Influence Bias: A Randomized Experiment
Authors: Muchnik Lev , Aral Sinan , Taylor Sean J.
Published: August 2013

Follow the Leader?

The Internet has increased the likelihood that our decisions will be influenced by those being made around us. On the one hand, group decision-making can lead to better decisions, but it can also lead to “herding effects” that have resulted in financial disasters.

Muchnik
et al.

(p.
647
) examined the effect of collective information via a randomized experiment, which involved collaboration with a social news aggregation Web site on which readers could vote and comment on posted comments. Data were collected and analyzed after the Web site administrators arbitrarily voted positively or negatively (or not at all) as the first comment on more than 100,000 posts. False positive entries led to inflated subsequent scores, whereas false negative initial votes had small long-term effects. Both the topic being commented upon and the relationship between the poster and commenter were important. Future efforts will be needed to sort out how to correct for such effects in polls or other collective intelligence systems in order to counter social biases.
A Semi-Floating Gate Transistor for Low-Voltage Ultrafast Memory and Sensing Operation
Authors: Wang Peng-Fei , Lin Xi , Liu Lei , Sun Qing-Qing , Zhou Peng , Liu Xiao-Yong , Liu Wei , Gong Yi , Zhang David Wei
Published: August 2013

Faster at the Gate

Advanced designs will be needed to continue to improve the performance of the main components of high-speed computing, metal-oxide semiconductor field-effect transistors (MOSFETs) and floating-gate (FG) MOSFETs.

Wang
et al.

(p. 640) fabricated a semi-floating gate (SFG) transistor in which a tunneling field-effect transistor couples the positively doped floating gate to the negatively doped drain region. The charge stored on the SFG was used to shift the voltage threshold for switching the transistor, which in turn sped up its operation and lowered the power consumed. These devices were used for ultrahigh-speed memory and in light sensing and imaging.
The End Times of Cold War Ecology
Arming Mother Nature
The Birth of Catastrophic Environmentalism

by Jacob Darwin Hamblin

Oxford University Press, Oxford, 2013. 308 pp. $29.95, £18.99. ISBN 9780199740055.
Authors: Mitman Gregg
Published: August 2013

Hamblin demonstrates the major role that prospects of a third world war played in shaping the study and diplomacy of global environmental change.
Who Will Pay for Public Access to Research Data?
Authors: Berman Francine , Cerf Vint
Published: August 2013

When economic models and infrastructure are not in place to ensure access and preservation, federally funded research data are “at risk.”
The Maturing Brain Methylome
Authors: Gabel Harrison W. , Greenberg Michael E.
Published: August 2013

DNA methylation patterns in the developing and adult mammalian brain point to a role in synaptic development and maturation.

[Also see Research Article by

Lister
et al.

]
Grim Day for Turkish Science as Six Academics Get Long Prison Terms
Authors: Bohannon John
Published: August 2013

On 5 August, half a dozen Turkish academics were sentenced to a decade or more in prison for crimes ranging from terrorism and treason to "insulting Turkishness."
Expansion of Serotype Coverage in the Universal Pediatric Vaccination Calendar: Short-Term Effects on Age- and Serotype-Dependent Incidence of Invasive Pneumococcal Clinical Presentations in Madrid, Spain
Authors: Picazo Juan , Ruiz-Contreras Jesus , Casado-Flores Juan , Negreira Sagrario , García-de-Miguel Maria-Jesus , Hernández-Sampelayo Teresa , Otheo Enrique , Méndez Cristina
Published: August 2013

In Madrid, Spain, the 13-valent pneumococcal conjugate vaccine (PCV13) replaced PCV7 in the pediatric universal vaccination calendar in June 2010. A prospective clinical surveillance that included all children hospitalized with culture- and/or PCR-confirmed invasive pneumococcal disease (IPD) was performed in all Madrid hospitals. The incidence rates (IRs) (defined as the number of cases/100,000 inhabitants aged <15 years) in the PCV7 (May 2007 to April 2010) versus PCV13 (May 2011 to April 2012) periods were compared. There were 499 cases in the PCV7 period and 79 cases in the PCV13 period. Globally, the IR significantly decreased from 17.09 (PCV7 period) to 7.70 (PCV13 period), with significant decreases (PCV7 versus PCV13 periods) in all age groups for bacteremic pneumonia (5.51 versus 1.56), parapneumonic pneumococcal empyema (PPE) (5.72 versus 3.12), and meningitis (2.16 versus 0.97). In the PCV13 period, significant reductions (the IR in the PCV7 period versus the IR in the PCV13 period) were found in IPDs caused by PCV13 serotypes (13.49 versus 4.38), and specifically by serotypes 1 (globally [4.79 versus 2.53], for bacteremic pneumonia [2.23 versus 0.97], and for PPE [2.26 versus 1.17]), serotype 5 (globally [1.88 versus 0.00], for bacteremic pneumonia [0.89 versus 0.00], and for PPE [0.55 versus 0.00]), and serotype 19A (globally [3.77 versus 0.49], for bacteremic pneumonia [0.72 versus 0.00], for PPE [0.89 versus 0.00], and for meningitis [0.62 versus 0.00]). IPDs caused by non-PCV13 serotypes did not increase (IR, 3.60 in the PCV7 period versus 3.31 in the PCV13 period), regardless of age or presentation. No IPDs caused by the PCV13 serotypes were found in children who received 3 doses of PCV13. The number of hospitalization days and sanitary costs were significantly lower in the PCV13 period. The switch from PCV7 to PCV13 in the universal pediatric vaccination calendar provided sanitary and economical benefits without a replacement by non-PCV13 serotypes.
Lipids Derived from Virulent Francisella tularensis Broadly Inhibit Pulmonary Inflammation via Toll-Like Receptor 2 and Peroxisome Proliferator-Activated Receptor α
Authors: Crane Deborah D. , Ireland Robin , Alinger Joshua B. , Small Pamela , Bosio Catharine M.
Published: August 2013

Francisella tularensisis a Gram-negative facultative intracellular pathogen that causes an acute lethal respiratory disease in humans. The heightened virulence of the pathogen is linked to its unique ability to inhibit Toll-like receptor (TLR)-mediated inflammatory responses. The bacterial component and mechanism of this inhibition are unknown. Here we show that lipids isolated from virulent but not attenuated strains ofF. tularensisare not detected by host cells, inhibit production of proinflammatory cytokines by primary macrophages in response to known TLR ligands, and suppress neutrophil recruitmentin vivo. We further show that lipid-mediated inhibition of inflammation is dependent on TLR2, MyD88, and the nuclear hormone and fatty acid receptor peroxisome proliferator-activated receptor α (PPARα). Pathogen lipid-mediated interference with inflammatory responses through the engagement of TLR2 and PPARα represents a novel manipulation of host signaling pathways consistent with the ability of highly virulentF. tularensisto efficiently evade host immune responses.
A Case of Mild Pulmonary Disease Due to Mycobacterium shimoidei with a Favorable Outcome
Authors: Galizzi Nadia , Tortoli Enrico , Gori Andrea , Morini Fulvia , Lapadula Giuseppe
Published: August 2013

We describe a case of mild
Mycobacterium shimoidei
disease with a favorable course after treatment. Characteristics of nine
M. shimoidei
isolates in Italy between 1989 and 2009 were also reviewed. The
M. shimoidei
genome was highly conserved. Based on antimicrobial susceptibility, the combination of ethambutol, clarithromycin, and rifabutin appears to be a reasonable treatment.
Comparison of Perirectal versus Rectal Swabs for Detection of Asymptomatic Carriers of Toxigenic Clostridium difficile
Authors: Rogers David S. , Kundrapu Sirisha , Sunkesula Venkata C. K. , Donskey Curtis J.
Published: August 2013

For long-term care and spinal cord injury patients, the sensitivity, specificity, and positive and negative predictive values of perirectal versus rectal cultures for detection of asymptomatic carriers of
Clostridium difficile
were 95%, 100%, 100%, and 97%, respectively. Perirectal cultures provide an accurate method to detect asymptomatic carriers of
C. difficile
.
Multiple Broad-Spectrum Beta-Lactamase Targets for Comprehensive Surveillance
Authors: Mangold Kathy A. , Voss Barbara L. , Singh Kamaljit , Thomson Richard B. , Schora Donna M. , Peterson Lance R. , Kaul Karen L.
Published: August 2013

Real-time PCR testing for
bla
KPC
,
bla
NDM
,
bla
VIM
,
bla
IMP
, and
bla
CTX-M
was performed on rectal swabs obtained from residents of two long-term acute-care facilities. While
bla
KPC
was detected in 69/102 swabs (67.6%), testing for four other targets increased the positivity rate for a broad-spectrum β-lactamase to 73.5% (McNemar's
P
= 0.03).
Antimicrobial Stewardship Programs
Authors: Leuthner Kimberly D. , Doern Gary V.
Published: August 2013

The development of antimicrobial agents represents one of the most significant achievements in medicine during the past century. However, the emergence of antimicrobial resistance combined with the downturn in the development of new antimicrobial agents in the pharmaceutical industry poses unanticipated challenges in the effective management of infection. The issue of how we can most effectively utilize these invaluable resources, antimicrobials, in the face of infections that are ever more difficult to treat arises. This issue serves as the fundamental basis for the concept of antimicrobial stewardship, the topic of this minireview.
The PA and HA Gene-Mediated High Viral Load and Intense Innate Immune Response in the Brain Contribute to the High Pathogenicity of H5N1 Avian Influenza Virus in Mallard Ducks
Authors: Hu Jiao , Hu Zenglei , Mo Yiqun , Wu Qiwen , Cui Zhu , Duan Zhiqiang , Huang Junqing , Chen Hongzhi , Chen Yuxin , Gu Min , Wang Xiaoquan , Hu Shunlin , Liu Huimou , Liu Wenbo , Liu Xiaowen , Liu Xiufan
Published: August 2013

Most highly pathogenic avian influenza A viruses cause only mild clinical signs in ducks, serving as an important natural reservoir of influenza A viruses. However, we isolated two H5N1 viruses that are genetically similar but differ greatly in virulence in ducks. A/Chicken/Jiangsu/k0402/2010 (CK10) is highly pathogenic, whereas A/Goose/Jiangsu/k0403/2010 (GS10) is low pathogenic. To determine the genetic basis for the high virulence of CK10 in ducks, we generated a series of single-gene reassortants between CK10 and GS10 and tested their virulence in ducks. Expression of the CK10 PA or hemagglutinin (HA) gene in the GS10 context resulted in increased virulence and virus replication. Conversely, inclusion of the GS10 PA or HA gene in the CK10 background attenuated the virulence and virus replication. Moreover, the PA gene had a greater contribution. We further determined that residues 101G and 237E in the PA gene contribute to the high virulence of CK10. Mutations at these two positions produced changes in virulence, virus replication, and polymerase activity of CK10 or GS10. Position 237 plays a greater role in determining these phenotypes. Moreover, the K237E mutation in the GS10 PA gene increased PA nuclear accumulation. Mutant GS10 viruses carrying the CK10 HA gene or the PA101G or PA237E mutation induced an enhanced innate immune response. A sustained innate response was detected in the brain rather than in the lung and spleen. Our results suggest that the PA and HA gene-mediated high virus replication and the intense innate immune response in the brain contribute to the high virulence of H5N1 virus in ducks.
Emergence of a C-Terminal Seven-Amino-Acid Elongation of NS1 in Around 1950 Conferred a Minor Growth Advantage to Former Seasonal Influenza A Viruses
Authors: Lohrmann Florens , Dijkman Ronald , Stertz Silke , Thiel Volker , Haller Otto , Staeheli Peter , Kochs Georg
Published: August 2013

Influenza A viruses circulating in humans from ∼1950 to ∼1987 featured a nonstructural (NS1) protein with a C-terminal extension of seven amino acids. The biological significance of this NS1 elongation remained elusive. We observed that replication kinetics of the wild-type virus A/Hong Kong/01/68 (H3N2) and a mutant encoding a truncated NS1 were indistinguishable in most experimental systems. However, wild-type virus outcompeted the mutant during mixed infections, suggesting that the NS1 extension conferred minor growth advantages.