bluuebunny/crossref_metadata_2025 huggingface dataset:
Prediction of blind frequency in lock-in thermography using electro-thermal model based numerical simulation
Authors: Chatterjee Krishnendu , Tuli Suneet
Published: November 2013

Lock-in thermography is increasingly becoming popular as a non-destructive testing technique for defect detection in composite materials for its low heating excitation. The experimental data is processed with Fourier transformation to produce phase and amplitude images. Phase images, though immune to surface emissivity variation, suffer from blind frequency effect, where a defect becomes invisible at a certain excitation frequency. There exists no analytical model to predict this 3-dimensional heat flow phenomenon. This paper presents a study of blind frequency using electro-thermal model based numerical simulation on a piece of thermally anisotropic carbon fibre composite. The performance of the simulator is optimized for spatial mesh size. Further the effect of paint layer, which is often applied to the sample surface for better thermal imaging, has been incorporated in the simulation. Finally, both experimental and simulation results are presented side-by-side for easy comparison.
Quasi-elastic neutron scattering in the multi-GPa range and its application to liquid water
Authors: Klotz S. , Strässle Th. , Bove L. E.
Published: November 2013

We present a method which allows quasi-elastic neutron scattering (QENS) at multi-GPa pressures, i.e., pressure conditions which are an order of magnitude higher than possible with QENS till now. The technique uses an opposed-anvil geometry with a sample chamber in the form of a toroid which minimizes multiple scattering effects. This method has been applied to measurements of the self-diffusion coefficient of water at 400 K up to 3 GPa. The results demonstrate the potential of this method for studying diffusion over a large pressure and temperature range.
Fano resonances of microwave structures with embedded magneto-dipolar quantum dots
Authors: Kamenetskii E. O. , Vaisman G. , Shavit R.
Published: November 2013

Long range dipole-dipole correlation in a ferromagnetic sample can be treated in terms of collective excitations of the system as a whole. Ferrite samples with linear dimensions smaller than the dephasing length, but still much larger than the exchange-interaction scales, are mesoscopic structures. Recently, it was shown that mesoscopic quasi-2D ferrite disks, distinguishing by multiresonance magneto-dipolar-mode (MDM) spectra, demonstrate unique properties of artificial atomic structures: energy eigenstates, eigen power-flow vortices, and eigen helicity parameters. Because of these properties, MDMs in a ferrite disk enable the confinement of microwave radiation to subwavelength scales. In microwave structures with embedded MDM ferrite samples, one can observe quantized fields with topologically distinctive characteristics. The use of a quasi-2D ferrite-disk scatterer with internal MDM resonance spectra along the channel propagation direction could change the transmission dramatically. In this paper, we show that interaction of the MDM ferrite particle with its environment has a deep analogy with the Fano-resonance interference observed in natural and artificial atomic structures. We characterize the observed effect as Fano-resonance interference in MDM quantum dots.
Note: Evidence against 2D-Ising criticality in aqueous solutions with added salt
Authors: Troncoso Jacobo , Cerdeiriña Claudio A.
Published: November 2013

Coexistence-curve data in the refractive index-temperature plane for solutions of 3-methyl-pyridine in heavy water with a small amount of added sodium tetraphenylborate have been determined. The analysis of such data indicates that this system belongs to the universality class of the three-dimensional Ising model (3D-Ising). This finding contrasts with previous work by Sadakane et al. [Soft Matter 7, 1334 (2011)] in which 2D-Ising criticality is invoked, but agrees with the recent assessment by Leys et al. [Soft Matter 9, 9326 (2013)].
Eddy current step heating thermography for quantitatively evaluation
Authors: He Yunze , Pan Mengchun , Chen Dixiang , Tian GuiYun , Zhang Hong
Published: November 2013

This Letter proposed eddy current step heating thermography (ECSHT) combing eddy current excitation with SHT. It has been verified through numerical and experimental studies that the temperature-time1/2 curve can be used to detect the subsurface defects. Separation time was defined and extracted from temperature responses as characteristic feature. Experiment studies with mild steel sample were conducted, and the experimental results showed that two features representing separation time can be used to measure the defect's depth based on their linear relationships.
Hot-phonon-induced indirect absorption in silicon nanocrystals
Authors: Kozák M. , Kořínek M. , Trojánek F. , Hiller D. , Gutsch S. , Zacharias M. , Malý P.
Published: November 2013

We studied the nonlinear transient absorption dynamics in silicon nanocrystals/SiO2 superlattices. A different dependence of the measured dynamics on excitation intensity was observed depending on the relative position of the probe photon energy and the absorption edge of nanocrystals. At low photon energies, the dynamics changed with excitation fluence and the signal was ascribed to excited state absorption. However, at photon energies above the absorption edge, the phonon enhancement of indirect absorption prevails over excited state absorption what is reflected in excitation fluence independent dynamics of transient absorption.
Size effect of the subharmonic Shapiro steps on the interference phenomena in the Frenkel-Kontorova model with realistic substrate potentials
Authors: Tekić J. , Mali P. , Ivić Z. , Pantić M.
Published: November 2013

Size effect of the subharmonic Shapiro steps on the behavior of harmonic ones is studied in the ac driven overdamped Frenkel-Kontorova model with different types of physically important realistic substrate potentials. The properties of harmonic Shapiro steps are directly correlated with the size of halfinteger steps; and according to that in their amplitude dependence, three distinctive types of behavior have been classified. Our results on other realistic systems show that these classifications are not universal, and that not only the size of halfinteger steps but also the type of the substrate potential determines the properties and correlation between the Shapiro steps. While for some potentials such as variable and double-barrier potential, system evolves through different types of amplitude dependence as the size of halfinteger steps changes, in the case of double-well potential, the system maintains the standard behavior (the behavior for small halfinteger steps) even in the presence of large halfinteger steps.
Electrocaloric properties in relaxor ferroelectric (1−x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 system
Authors: Peräntie J. , Tailor H. N. , Hagberg J. , Jantunen H. , Ye Z.-G.
Published: November 2013

The electrocaloric effect (ECE) in the Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN-PT) solid solution system was investigated by means of detailed direct temperature measurements as a function of temperature, composition, and electric field. The (1−x)PMN-xPT ceramics of compositions 0 ≤ x ≤ 0.3 were fabricated by the columbite route. In opposite to conventional ferroelectrics, the maximum of electrocaloric effect was found to shift from the proximity of depolarization/Curie temperature to higher temperatures above a certain composition-dependent electric field strengths. Especially, the compositions with low PT content showed a broadened temperature range of electrocaloric effect. With increasing PbTiO3 concentration, the magnitude of ΔT increased, and the temperature dependence of the maximum ECE response gradually developed towards a more pronounced anomaly typical for conventional ferroelectrics. The arising high temperature electrocaloric effect in the ergodic relaxor phase was attributed to the contribution from polar nanoregions. All the compositions studied showed the highest electrocaloric activity just above the depolarization/Curie temperature close to the possible critical point, as recently predicted and observed for some compositions. The magnitude of the maximum electrocaloric temperature change was in the range of ΔT = 0.77–1.55 °C under an electric field strength of 50 kV/cm.
Heights on groups and small multiplicative dependencies
Authors: Vaaler Jeffrey
Published: November 2013

We generalize the absolute logarithmic Weil height from elements of the multiplicative groupQ¯×/Tor(Q¯×)\overline {\mathbb {Q}}^{\times }/\mathrm {Tor}\bigl (\overline {\mathbb {Q}}^{\times }\bigr )to finitely generated subgoups ofQ¯×/Tor(Q¯×)\overline {\mathbb {Q}}^{\times }/\mathrm {Tor}\bigl (\overline {\mathbb {Q}}^{\times }\bigr ). The height of a finitely generated subgroup is shown to equal the volume of a certain naturally occurring, convex, symmetric subset of Euclidean space. This connection leads to a bound on the norm of integer vectors that give multiplicative dependencies among finite sets of algebraic numbers.
V2 of tomato yellow leaf curl virus can suppress methylation-mediated transcriptional gene silencing in plants
Authors: Wang Bi , Li Fangfang , Huang Changjun , Yang Xiuling , Qian Yajuan , Xie Yan , Zhou Xueping
Published: November 2013

Tomato yellow leaf curl virus (TYLCV) is a DNA virus belonging to the genus Begomovirus. TYLCV replicates using double-stranded DNA intermediates that can become the target of plant transcriptional gene silencing (TGS). Here, we show that the V2 protein of TYLCV can suppress TGS of a transcriptionally silenced green fluorescent protein (GFP) transgene in Nicotiana benthamiana line 16-TGS. Through bisulfite sequencing and chop-PCR, we demonstrated that the TYLCV V2 can reverse GFP transgene silencing by reducing the methylation levels in the 35S promoter sequence. Both AtSN1 and MEA-ISR loci in Arabidopsis thaliana were previously reported to be strongly methylated, and we show that the methylation status of both loci was significantly reduced in TYLCV V2 transgenic Arabidopsis plants. We conclude that TYLCV can efficiently suppress TGS when it infects plants, and its V2 protein is responsible for the TGS suppression activity.
REVIEW: Beyond the fragmentation debate: a conceptual model to predict when habitat configuration really matters
Authors: Villard Marc‐André , Metzger Jean Paul
Published: November 2013

Research addressing the effects of habitat fragmentation on species, assemblages or ecosystems has been fraught with difficulties, from its conceptual foundation to statistical analyses and interpretation. Yet, it is critical to address such challenges as ecosystems are rapidly being altered across the world.

Many studies have concluded that effects of habitat loss exceed those of fragmentation per se, that is, the degree to which a given amount of habitat is broken apart. There is also evidence from different biomes and taxa that habitat configuration, that is, the spatial arrangement of habitat at a given time, may influence several landscape processes such as functional connectivity, edge and matrix effects, and thus population viability.

Instead of focusing attention on the relative influence of either habitat loss or fragmentation, we must identify portions of the gradient in habitat amount where configuration effects are most likely to be observed. Here, we suggest that all species are, to a certain degree, sensitive to landscape change and that, assuming a homogeneous matrix, habitat configuration will have a higher influence on species at intermediate values of habitat amount, where configuration has potentially the greatest variability.

On the basis of empirical studies and simulations, we expect that species that are relatively tolerant to fragmentation of their habitat will exhibit a wider band where amount and configuration interact compared to species less tolerant to fragmentation.

Synthesis and applications. Reducing habitat loss should be a top priority for conservation planners. However, researchers should also investigate the indirect impacts of habitat loss on biodiversity through fragmentation effects. This research aims to identify windows of opportunity where habitat configuration can mitigate to some extent the effects of habitat loss, particularly through the maintenance of functional connectivity.
Modelling flight heights of marine birds to more accurately assess collision risk with offshore wind turbines
Authors: Johnston Alison , Cook Aonghais S. C. P. , Wright Lucy J. , Humphreys Elizabeth M. , Burton Niall H. K.
Published: November 2013

The number of offshore wind farms is rapidly increasing as they are a critical part of many countries' renewable energy strategies. Quantifying the likely impacts of these developments on wildlife is a fundamental part of the impact assessments required in many regions before permission for developments is granted. A key concern related to wind turbines is the risk of birds colliding with turbine blades. We present a novel method to generate species‐specific flight height distributions which can be used to improve the assessment of collision risk by better reflecting the proportion of in‐flight populations at risk of collision.

Data describing the flight heights of birds from surveys of 32 potential offshore wind farm development sites were combined to estimate continuous distributions for 25 marine bird species. Observations of flying birds assigned to discrete height categories were treated as observations from independent multinomial distributions with a shared underlying continuous distribution. This analysis enables calculation of the uncertainty around the estimates of the proportion of the in‐flight population at risk and consideration of different turbine designs.

The mean r2 for model fit across species was 0·85, and for seven of the species, good independent model validation (80% of independent observations within 95% confidence intervals) provides some confidence for use of the results at alternative sites.

All species exhibited positively skewed flight height distributions. These results demonstrate that under the conditions in which the data were collected, raising hub height and using fewer, larger turbines are effective measures for reducing collision risk.

Synthesis and applications. The methods presented here for modelling continuous flight height distributions provide measures of uncertainty and enable comparison of collision risk between different turbine designs. This approach will improve the accuracy of impact assessments and provide estimates of uncertainty, allowing better evidence to inform decision‐making.
A Gateway®‐compatible bacterial adenylate cyclase‐based two‐hybrid system
Authors: Ouellette Scot P. , Gauliard Emilie , Antosová Zuzana , Ladant Daniel
Published: November 2013

The bacterial adenylate cyclase two‐hybrid (BACTH) system has been widely used to characterize protein–protein interactions in the prokaryotic world. This system relies on the interaction‐mediated reconstitution of adenylate cyclase activity in Escherichia coli by bringing together two complementary fragments of the catalytic domain of the adenylate cyclase toxin of Bordetella pertussis. A limiting factor in performing large‐scale two‐hybrid interaction screens with full‐length open reading frames (ORFs) is the need to clone each ORF individually into the plasmids used to express the hybrid proteins. The Gateway® (GW) cloning system (Life Technologies, Grand Island, NY, USA) partially circumvents this limitation, and we describe here modifications to the BACTH system for compatibility with this recombineering technology. We validated and tested the functionality of the BACTH Gateway (BACTHGW) system using several models of protein–protein interactions, focusing particularly on those involved in bacterial cell division. We further modified the BACTH plasmids to incorporate a transmembrane (TM) segment downstream of the cyclase fragments to permit analysis of extracytoplasmic protein interactions. This approach was also useful to identify putative TM segments and to experimentally validate bioinformatically identified TM domains. The BACTHGW system will prove a useful addition to the study of protein–protein interactions.
Capital Controls and International Development: A Theoretical Reconsideration
Authors: Sheng Li
Published: November 2013

This survey article develops a stochastic framework to analyze capital inflows and outflows and to illustrate how a developing economy can determine its level of capital account openness and simultaneously balance concerns regarding economic growth and volatility. We find that rapid economic growth inevitably causes fluctuations in a financially immature economy that has a high level of capital account openness. We identify a conflict of interest between capital‐rich and capital‐importing economies when capital account liberalization is promoted by the former.
The expression of prostaglandin receptors EP3 and EP4 in human cervix in post‐term pregnancy differs between failed and successful labor induction
Authors: Roos Nathalie , Blesson Chellakkan S. , Stephansson Olof , Masironi Britt , Vladic Stjernholm Ylva , Ekman‐Ordeberg Gunvor , Sahlin Lena
Published: November 2013

Objective

To investigate expression and localization of prostaglandin receptors EP1‐4 and FP and localization of stromal factors CTGF (connective tissue growth factor), furin, calgranulin B and ALOX15 (arachidonate 15‐lipooxygenase) in human cervical tissue from post‐term women with failed or successful labor induction after prostaglandin priming.

Design

Experimental prospective clinical study.

Setting

Tertiary obstetric care center.

Population

Twenty‐six women giving birth post‐term, with failed or successful labor induction, and a control group consisting of 19 women with spontaneous onset of labor and delivery at term.

Methods

Biopsies were obtained from post‐term women with successful (responders; R) and failed (non‐responders; NR) labor induction. Women with spontaneous delivery at term were included as controls (C). mRNA expression was determined with real time PCR, protein expression and localization with immunohistochemistry.

Main outcome measures

Comparisons of mRNA and protein expressions between post‐term pregnancies with failed and successful labor induction as well as term controls.

Results

EP4 mRNA expression was down‐regulated concomitant with an up‐regulation of EP3 mRNA expression in cervix from the NR group as compared with the R group. In stroma, immunoreactivity of the EP4 protein was increased in the NR group as compared with R and C groups.

Conclusions

Failure of cervical ripening, after local application of prostaglandins for labor induction, may be caused by the increased expression of EP3 and concomitant decrease in EP4 expression.
Stable Isotope Analysis of Human and Faunal Remains in the Western Loess Plateau, Approximately 2000 cal bc
Authors: Ma M. M. , Dong G. H. , Lightfoot E. , Wang H. , Liu X. Y. , Jia X. , Zhang K. R. , Chen F. H.
Published: November 2013

During the second millennium bc, several significant changes were happening in prehistoric societies across Eurasia. For instance, shifts in subsistence practice occurred in north‐western China, including the western Loess Plateau. However, the magnitude and nature of this dietary change are unclear and more detailed information and regional studies are needed in order to fully understand the reasons behind this change. In this study, palaeodiet is investigated at three sites (Xiahaishi, Buziping and Buzishan) in the western Loess Plateau, all dating to c.2000 cal bc, through stable isotope analysis of human and faunal remains, in order to explore the socio‐economic conditions prior to the subsistence shift. In general, humans and omnivores (Canis and Sus) had diets dominated by millet. Compared to other sites in Gansu Province, the humans and omnivores in this study were more reliant upon millet‐based agriculture, and millet‐based agriculture was more important and productive in the western Loess Plateau around 2000 cal bc.
Genetic perspectives on northern population cycles: bridging the gap between theory and empirical studies
Authors: Norén Karin , Angerbjörn Anders
Published: November 2013

Many key species in northern ecosystems are characterised by high‐amplitude cyclic population demography. In 1924,CharlesElton described the ecology and evolution of cyclic populations in a classic paper and, since then, a major focus has been the underlying causes of population cycles. Elton hypothesised that fluctuations reduced population genetic variation and influenced the direction of selection pressures. In concordance withElton, present theories concern the direct consequences of population cycles for genetic structure due to the processes of genetic drift and selection, but also include feedback models of genetic composition on population dynamics. Most of these theories gained mathematical support during the 1970s and onwards, but due to methodological drawbacks, difficulties in long‐term sampling and a complex interplay between microevolutionary processes, clear empirical data allowing the testing of these predictions are still scarce. Current genetic tools allow for estimates of genetic variation and identification of adaptive genomic regions, making this an ideal time to revisit this subject. Herein, we attempt to contribute towards a consensus regarding the enigma described byElton almost 90 years ago. We present nine predictions covering the direct and genetic feedback consequences of population cycles on genetic variation and population structure, and review the empirical evidence. Generally, empirical support for the predictions was low and scattered, with obvious gaps in the understanding of basic population processes. We conclude that genetic variation in northern cyclic populations generally is high and that the geographic distribution and amount of diversity are usually suggested to be determined by various forms of context‐ and density‐dependent dispersal exceeding the impact of genetic drift. Furthermore, we found few clear signatures of selection determining genetic composition in cyclic populations. Dispersal is assumed to have a strong impact on genetic structuring and we suggest that the signatures of other microevolutionary processes such as genetic drift and selection are weaker and have been over‐shadowed by density‐dependent dispersal. We emphasise that basic biological and demographical questions still need to be answered and stress the importance of extensive sampling, appropriate choice of tools and the value of standardised protocols.
bioclim: the first species distribution modelling package, its early applications and relevance to most current MaxEnt studies
Authors: Booth Trevor H. , Nix Henry A. , Busby John R. , Hutchinson Michael F.
Published: November 2013

Aim

Interest in species distribution models (SDMs) and related niche studies has increased dramatically in recent years, with several books and reviews being prepared since 2000. The earliest SDM studies are dealt with only briefly even in the books. Consequently, many researchers are unaware of when the first SDM software package (bioclim) was developed and how a broad range of applications using the package was explored within the first 8 years following its release. The purpose of this study is to clarify these early developments and initial applications, as well as to highlight bioclim's continuing relevance to current studies.

Location

Mainly Australia and New Zealand, but also some global applications.

Methods

We outline the development of the bioclim package, early applications (1984–1991) and its current relevance.

Results

bioclim was the first SDM package to be widely used. Early applications explored many of the possible uses of SDMs in conservation biogeography, such as quantifying the environmental niche of species, identifying areas where a species might be invasive, assisting conservation planning and assessing the likely impacts of climate change on species distributions.

Main conclusions

Understanding this pioneering work is worthwhile as bioclim was for many years one of the leading SDM packages and remains widely used. Climate interpolation methods developed for bioclim were used to create the WorldClim database, the most common source of climate data for SDM studies, and bioclim variables are used in about 76% of recent published MaxEnt analyses of terrestrial ecosystems. Also, some of the bioclim studies from the late 1980s, such as measuring niche (both realized and fundamental) and assessing possible impacts of climate change, are still highly relevant to key conservation biogeography issues.
China: Saviour or Challenger of the Dollar Hegemony?
Authors: Hung Ho‐fung
Published: November 2013

Since the collapse of the Bretton Woods monetary order in 1971, the US dollar has successfully maintained its global hegemony despite the US's declining share in the global economy, thanks largely to the US's political‐military supremacy. The recent rise of China poses a serious dilemma to the US. On the one hand, China's export‐oriented development has provided the US with low‐cost manufactured imports and cheap credit. On the other hand, the US's expanding current account deficit, largely attributable to China, has precipitated a crisis of confidence over the dollar's long‐term viability. This dilemma explains the US's vacillation in its currency conflict with China over the last decade. China has also been caught in a dilemma. While keeping its currency cheap could help sustain its export competitiveness, it would deepen China's dependence on the US market and Treasury bonds as an outlet for its expanding current account surplus. On the other hand, while a RMB revaluation would facilitate China's long overdue economic rebalancing and reduce its dependence on the US, the resulting unravelling of the long‐entrenched export‐oriented growth could generate large‐scale economic dislocation. No matter how this currency conflict is settled, its final resolution will determine the future of the dollar's global hegemony.
Globalization with Chinese Characteristics: Externalization, Dynamics and Transformations
Authors: Henderson Jeffrey , Appelbaum Richard P. , Ho Suet Ying
Published: November 2013

This article introduces a special issue on globalization ‘with Chinese characteristics’, but also makes its own contribution to the debates. It does so by focusing on the implications of China's rise for the nature and consequences of globalization as a distinct formation. It argues that globalization needs to be understood, in part, as the externalization of particular national forms of capitalism in particular historical periods. In this context, it explores the Chinese form in some detail, arguing that this form is likely to provide much of the initial character of a new, emergent version of globalization now in train. The ways China (and other ‘rising powers’) are beginning to impact other parts of the developing world presages the need for a new approach to the analysis of ‘development’. This article is critical of traditional discourses, and argues that innovation around the concept of ‘transformation’, including a focus on ‘conjunctures of critical transformation’, may lead to more appropriate and adequate analyses of development and open up those analyses more effectively to ‘non‐Western’ voices. The authors discuss the ‘vectors’ by which China's externalization is transforming the developing world. They mobilize arguments from the other articles in the special issue, in order both to introduce their contributions to the relevant debates and to use their arguments as materials for the particular contribution this article provides.
Clustering of cultural industries in Chinese cities
Authors: Ko Kwan Wai , Mok Kin Wai Patrick
Published: November 2013

This study is the first empirical research on understanding the determinants of the concentration of cultural industries (CIs) in cities in China. What factors of the urban environment are important for attracting the location of CIs? How is the development of CIs in a city influenced by its neighbouring cities and its early development? To answer these questions, three types of spatial panel models – the spatial lag model, the spatial error model and the spatial dynamic panel model – are employed using the urban statistics for China from 2003 to 2009. Human capital, diversified industrial structure and transportation and communication infrastructure are significant factors contributing to the development of CIs. The empirical findings reveal the presence of positive spatial spillovers among cities, which suggests that promoting CIs in one city benefits other cities. Also, the evidence suggests the presence of temporal spillovers, implying that the early concentration of CIs in a city tends to attract more CIs in that city.
Evaluation of rockfish conservation area networks in the United States and Canada relative to the dispersal distance for black rockfish (Sebastes melanops)
Authors: Lotterhos Katie E. , Dick Stefan J. , Haggarty Dana R.
Published: November 2013

Marine reserves networks are implemented as a way to mitigate the impact of fishing on marine ecosystems. Theory suggests that a reserve network will function synergistically when connected by dispersal, but the scale of dispersal is often unknown. On the Pacific coast of the United States and Canada, both countries have recently implemented a number of rockfish conservation areas (RCAs) to protect exploited rockfish species, but no study has evaluated the connectivity within networks in each country or between the two countries. We used isolation‐by‐distance theory to estimate the scale of dispersal from microsatellite data in the black rockfish, Sebastes melanops, and compared this estimate with the distance between RCAs that would protect this species. Within each country, we found that the distance between RCAs was generally within the confidence intervals of mean dispersal per generation. The distance between these two RCA networks, however, was greater than the average dispersal per generation. The data were also consistent with a genetic break between southern Oregon and central Oregon. We discuss whether additional nearshore RCAs in southern Oregon and Washington would help promote connectivity between RCA's for shallow‐water rockfishes.
Equine temporomandibular joint (TMJ) disease: Fact or fiction?
Authors: Carmalt J. L.
Published: November 2013

See also article by Barnett et al.
pH‐Dependent hydrolase, glutaminase, transpeptidase and autotranspeptidase activities of Bacillus subtilis γ‐glutamyltransferase
Authors: Morelli Carlo F. , Calvio Cinzia , Biagiotti Marco , Speranza Giovanna
Published: November 2013

γ‐Glutamyltransferases (γ‐GTs) are heterodimeric enzymes that catalyze the transfer of a γ‐glutamyl group from a donor species to an acceptor molecule in a transpeptidation reaction through the formation of an intermediate γ‐glutamyl enzyme. In our search for a γ‐GT from a generally recognized as safe microorganism suitable for the production of γ‐glutamyl derivatives with flavor‐enhancing properties intended for human use, we cloned and overexpressed the γ‐GT from Bacillus subtilis. In this study, we report the behavior of B. subtilis γ‐GT in reactions involving glutamine as the donor compound and various acceptor amino acids. The common thread emerging from our results is a strong dependence of the hydrolase, transpeptidase and autotranspeptidase activities of B. subtilis γ‐GT on pH, also in relation to the pKa of the acceptor amino acids. Glutamine, commonly referred to as a poor acceptor molecule, undergoes rapid autotranspeptidation at elevated pH, affording oligomeric species, in which up to four γ‐glutamyl moieties are linked to a single glutamine. Moreover, we found that d‐glutamine is also recognized both as a donor and as an acceptor substrate. Our results prove that the B. subtilis γ‐GT‐catalyzed transpeptidation reaction is feasible, and the observed activities of γ‐GT from B. subtilis could be interpreted in relation to the known ability of the enzyme to process the polymeric material γ‐polyglutamic acid.
Characterization of a periplasmic nitrate reductase in complex with its biosynthetic chaperone
Authors: Dow Jennifer M. , Grahl Sabine , Ward Richard , Evans Rachael , Byron Olwyn , Norman David G. , Palmer Tracy , Sargent Frank
Published: November 2013

Escherichia coli is a Gram‐negative bacterium that can use nitrate during anaerobic respiration. The catalytic subunit of the periplasmic nitrate reductase NapA contains two types of redox cofactor and is exported across the cytoplasmic membrane by the twin‐arginine protein transport pathway. NapD is a small cytoplasmic protein that is essential for the activity of the periplasmic nitrate reductase and binds tightly to the twin‐arginine signal peptide of NapA. Here we show, using spin labelling and EPR, that the isolated twin‐arginine signal peptide of NapA is structured in its unbound form and undergoes a small but significant conformational change upon interaction with NapD. In addition, a complex comprising the full‐length NapA protein and NapD could be isolated by engineering an affinity tag onto NapD only. Analytical ultracentrifugation demonstrated that the two proteins in the NapDA complex were present in a 1 : 1 molar ratio, and small angle X‐ray scattering analysis of the complex indicated that NapA was at least partially folded when bound by its NapD partner. A NapDA complex could not be isolated in the absence of the NapA Tat signal peptide. Taken together, this work indicates that the NapD chaperone binds primarily at the NapA signal peptide in this system and points towards a role for NapD in the insertion of the molybdenum cofactor.

Structured digital abstract

NapD and NapA bind by x ray scattering (View interaction)

NapA and NapD physically interact by molecular sieving (View interaction)

NapA and NapD bind by electron paramagnetic resonance (View interaction)
GTP binding controls complex formation by the human ROCO protein MASL1
Authors: Dihanich Sybille , Civiero Laura , Manzoni Claudia , Mamais Adamantios , Bandopadhyay Rina , Greggio Elisa , Lewis Patrick A.
Published: November 2013

The human ROCO proteins are a family of multi‐domain proteins sharing a conserved ROC‐COR supra‐domain. The family has four members: leucine‐rich repeat kinase 1 (LRRK1), leucine‐rich repeat kinase 2 (LRRK2), death‐associated protein kinase 1 (DAPK1) and malignant fibrous histiocytoma amplified sequences with leucine‐rich tandem repeats 1 (MASL1). Previous studies of LRRK1/2 and DAPK1 have shown that the ROC (Ras of complex proteins) domain can bind and hydrolyse GTP, but the cellular consequences of this activity are still unclear. Here, the first biochemical characterization of MASL1 and the impact of GTP binding on MASL1 complex formation are reported. The results demonstrate that MASL1, similar to other ROCO proteins, can bind guanosine nucleotides via its ROC domain. Furthermore, MASL1 exists in two distinct cellular complexes associated with heat shock protein 60, and the formation of a low molecular weight pool of MASL1 is modulated by GTP binding. Finally, loss of GTP enhances MASL1 toxicity in cells. Taken together, these data point to a central role for the ROC/GTPase domain of MASL1 in the regulation of its cellular function.

Structured digital abstract

HSP60 and MASL1 physically interact by molecular sieving (View interaction)

MASL1 physically interacts with HSP70 and HSP60 by anti tag coimmunoprecipitation (View interaction)

MASL1 physically interacts with HSP60 by anti tag coimmunoprecipitation (View interaction)
Structure and expression profile of the sucrose synthase gene family in the rubber tree: indicative of roles in stress response and sucrose utilization in the laticifers
Authors: Xiao Xiaohu , Tang Chaorong , Fang Yongjun , Yang Meng , Zhou Binhui , Qi Jiyan , Zhang Yi
Published: November 2013

Sucrose synthase (Sus, EC 2.4.1.13) is widely recognized as a key enzyme in sucrose metabolism in plants. However, nothing is known about this gene family in Hevea brasiliensis (para rubber tree). Here, we identified six Sus genes in H. brasiliensis that comprise the entire Sus family in this species. Analysis of the gene structure and phylogeny of the Sus genes demonstrates evolutionary conservation in the Sus families across Hevea and other plant species. The expression of Sus genes was investigated via Solexa sequencing and quantitative PCR in various tissues, at various phases of leaf development, and under abiotic stresses and ethylene treatment. The Sus genes exhibited distinct but partially redundant expression profiles. Each tissue has one abundant Sus isoform, with HbSus3, 4 and 5 being the predominant isoforms in latex (cytoplasm of rubber‐producing laticifers), bark and root, respectively. HbSus1 and 6 were barely expressed in any tissue examined. In mature leaves (source), all HbSus genes were expressed at low levels, but HbSus3 and 4 were abundantly expressed in immature leaves (sink). Low temperature and drought treatments conspicuously induced HbSus5 expression in root and leaf, suggesting a role in stress responses. HbSus2 and 3 transcripts were decreased by ethylene treatment, consistent with the reduced sucrose‐synthesizing activity of Sus enzymes in the latex in response to ethylene stimulation. Our results are beneficial to further determination of functions for the Sus genes in Hevea trees, especially roles in regulating latex regeneration.
Commemorating the 1913 Michaelis–Menten paper Die Kinetik der Invertinwirkung: three perspectives
Authors: Deichmann Ute , Schuster Stefan , Mazat Jean‐Pierre , Cornish‐Bowden Athel
Published: November 2013

Methods and equations for analysing the kinetics of enzyme‐catalysed reactions were developed at the beginning of the 20th century in two centres in particular; in Paris, by Victor Henri, and, in Berlin, by Leonor Michaelis and Maud Menten. Henri made a detailed analysis of the work in this area that had preceded him, and arrived at a correct equation for the initial rate of reaction. However, his approach was open to the important objection that he took no account of the hydrogen‐ion concentration (a subject largely undeveloped in his time). In addition, although he wrote down an expression for the initial rate of reaction and described the hyperbolic form of its dependence on the substrate concentration, he did not appreciate the great advantages that would come from analysis in terms of initial rates rather than time courses. Michaelis and Menten not only placed Henri's analysis on a firm experimental foundation, but also defined the experimental protocol that remains standard today. Here, we review this development, and discuss other scientific contributions of these individuals. The three parts have different authors, as indicated, and do not necessarily agree on all details, in particular about the relative importance of the contributions of Michaelis and Menten on the one hand and of Henri on the other. Rather than force the review into an unrealistic consensus, we consider it appropriate to leave the disagreements visible.
Interaction between four flavonoids and trypsin: effect on the characteristics of trypsin and antioxidant activity of flavonoids
Authors: Li Qiong , Wei Qingyi , Yuan Erdong , Yang Jiguo , Ning Zhengxiang
Published: November 2013

Interaction of flavonoids and enzyme may affect characteristics and physiological activities of both components. In this study, the effects of the interaction between four flavonoids (quercetin, luteolin, kaempferol and apigenin) and trypsin were examined. At the concentration of 2.7 mm, inhibition of trypsin (1.6 U mL−1) by quercetin, luteolin, kaempferol and apigenin was 46.4%, 32.6%, 26.8% and 17.7%, respectively. In the presence of trypsin, DPPH, ABTS and hydroxyl radical scavenging activities of flavonoids were obviously inhibited. Addition of flavonoids led to fluorescence quenching of trypsin. The decreasing order of binding force between flavonoids and trypsin was quercetin, luteolin, kaempferol and apigenin. It is concluded that the interaction between flavonoids and trypsin depends on the number and position of hydroxyl group of flavonoids.
Training professionals' usage and understanding of Kirkpatrick's Level 3 and Level 4 evaluations
Authors: Kennedy Perri Estes , Chyung Seung Youn , Winiecki Donald J. , Brinkerhoff Robert O.
Published: November 2013

Training professionals have long acknowledged the necessity of conducting behavior‐based (Level 3) and results‐based (Level 4) evaluations, yet organizations do not frequently conduct such evaluations. This research examined training professionals' perceptions of the utility of Level 3 and Level 4 evaluations and the factors that facilitate or obstruct their attempts to perform them. The research was conducted using Brinkerhoff's Success Case Method and Gilbert's Behavior Engineering Model as its frameworks. The three key factors identified by study participants as having an impact upon their ability to conduct Level 3 and Level 4 evaluations were the availability of resources such as time and personnel, managerial support (organizational) and expertise in evaluative methodology (individual). The research findings indicated a need to further explore how training professionals interpret Level 3 and Level 4 and how they can better develop their evaluative expertise, which in turn may increase effectiveness in gaining organizational support for evaluation efforts.
N‐Ethyl‐N‐nitrosourea mutagenesis in the mouse provides strong genetic and in vivo evidence for the role of the Caspase Recruitment Domain (CARD) of CARD‐MAGUK1 in T regulatory cell development
Authors: Salisbury Emma M. , Wang Lihui , Choi Onjee , Rutschmann Sophie , Ashton‐Rickardt Philip G.
Published: November 2013

Natural regulatory T (nTreg) cells generated in the thymus are essential throughout life for the maintenance of T‐cell homeostasis and the prevention of autoimmunity. T‐cell receptor (TCR)/CD28‐mediated activation of nuclear factor‐κB and (J)un (N)‐terminal kinase pathways is known to play a key role in nTreg cell development but many of the predicted molecular interactions are based on extrapolations from non‐Treg cell TCR stimulation with non‐physiological ligands. For the first time, we provide strong genetic evidence of a scaffold function for the Caspase Recruitment Domain (CARD) of the TCR signalling protein CARD‐MAGUK1 (CARMA1) in nTreg cell development in vivo. We report two, new, N‐ethyl‐N‐nitrosourea‐derived mutant mice, Vulpo and Zerda, with a profound block in the development of nTreg cells in the thymus as well as impaired inducible Treg cell differentiation in the periphery. Despite independent heritage, both mutants harbour different point mutations in the CARD of the CARMA1 protein. Mutations in vulpo and zerda do not affect expression levels of CARMA1 but still impair signalling through the TCR due to defective downstream Bcl‐10 recruitment by the mutated CARD of CARMA1. Phenotypic differences observed between Vulpo and Zerda mutants suggest a role for the CARD of CARMA1 independent of Bcl‐10 activation of downstream pathways. We conclude that our forward genetic approach demonstrates a critical role for the CARD function of CARMA1 in Treg cell development in vivo.
Protection against collagen‐induced arthritis in mice afforded by the parasitic worm product, ES‐62, is associated with restoration of the levels of interleukin‐10‐producing B cells and reduced plasma cell infiltration of the joints
Authors: Rodgers David T. , Pineda Miguel A. , McGrath Mairi A. , Al‐Riyami Lamyaa , Harnett William , Harnett Margaret M.
Published: November 2013

We have previously reported that ES‐62, a molecule secreted by the parasitic filarial nematode Acanthocheilonema viteae, protects mice from developing collagen‐induced arthritis (CIA). Together with increasing evidence that worm infection may protect against autoimmune conditions, this raises the possibility that ES‐62 may have therapeutic potential in rheumatoid arthritis and hence, it is important to fully understand its mechanism of action. To this end, we have established to date that ES‐62 protection in CIA is associated with suppressed T helper type 1 (Th1)/Th17 responses, reduced collagen‐specific IgG2a antibodies and increased interleukin‐10 (IL‐10) production by splenocytes. IL‐10‐producing regulatory B cells have been proposed to suppress pathogenic Th1/Th17 responses in CIA: interestingly therefore, although the levels of IL‐10‐producing B cells were decreased in the spleens of mice with CIA, ES‐62 was found to restore these to the levels found in naive mice. In addition, exposure to ES‐62 decreased effector B‐cell, particularly plasma cell, infiltration of the joints, and such infiltrating B cells showed dramatically reduced levels of Toll‐like receptor 4 and the activation markers, CD80 and CD86. Collectively, this induction of hyporesponsiveness of effector B‐cell responses, in the context of the resetting of the levels of IL‐10‐producing B cells, is suggestive of a modulation of the balance between effector and regulatory B‐cell responses that may contribute to ES‐62‐mediated suppression of CIA‐associated inflammation and inhibition of production of pathogenic collagen‐specific IgG2a antibodies.
Reflections on T. Berry Brazelton, MD's Influence on Pediatric Nursing
Authors: Stadtler Ann Coleman , Brandt Kristie A. , Novak Julie C. , Beauchesne Michelle A.
Published: November 2013

Purpose

The purpose of this article is to provide examples of Dr. Brazelton's important influence on pediatric nursing, and by extension, the work of child psychiatric mental health nurses, the care of children and families, and ultimately, the healthcare delivery system.

Sources

Dr. Brazelton's professional colleagues, research, professional journals, and books.

Conclusion

Over the past 40 years, T. Berry Brazelton has had a major impact on the development of pediatric nursing, infant mental health, and the nurse practitioner movement. He has influenced the growth and development of nursing organizations, nursing education, nursing research, nursing practice, and health policy affecting nurses.
The Role of the EU in Shaping FDI Flows to East Central Europe
Authors: Medve‐Bálint Gergő
Published: November 2013

East Central Europe's (ECE) recent record in accumulating FDI stock is notable even from a global perspective. While most scholarly works downplay the role of the European Union (EU) in this process, this article claims that in an attempt to manage the economic opportunities and threats that ECE posed after the regime change, the EU has actively shaped foreign capital inflows to the region. First, the EU triggered a liberal shift in ECE's FDI policies. Second, after enlargement, the EU has reinforced ECE's locational advantages through its practice of approving most of the incentive schemes offered to foreign investors. While investors mainly coming from the old EU Members began to dominate ECE economies, the region's heavy reliance on FDI has also produced a reverse effect: ECE investments have enhanced the global competitiveness of western European firms. To a certain extent, FDI has therefore transcended the traditional east–west divide.