bluuebunny/crossref_metadata_2025 huggingface dataset:
Eco-evolutionary dynamics in urbanized landscapes: evolution, species sorting and the change in zooplankton body size along urbanization gradients
Authors: Brans Kristien I. , Govaert Lynn , Engelen Jessie M. T. , Gianuca Andros T. , Souffreau Caroline , De Meester Luc
Published: December 2016

Urbanization causes both changes in community composition and evolutionary responses, but most studies focus on these responses in isolation. We performed an integrated analysis assessing the relative contribution of intra- and interspecific trait turnover to the observed change in zooplankton community body size in 83 cladoceran communities along urbanization gradients quantified at seven spatial scales (50–3200 m radii). We also performed a quantitative genetic analysis on 12
Daphnia magna
populations along the same urbanization gradient. Body size in zooplankton communities generally declined with increasing urbanization, but the opposite was observed for communities dominated by large species. The contribution of intraspecific trait variation to community body size turnover with urbanization strongly varied with the spatial scale considered, and was highest for communities dominated by large cladoceran species and at intermediate spatial scales. Genotypic size at maturity was smaller for urban than for rural
D. magna
populations and for animals cultured at 24°C compared with 20°C. While local genetic adaptation likely contributed to the persistence of
D. magna
in the urban heat islands, buffering for the phenotypic shift to larger body sizes with increasing urbanization, community body size turnover was mainly driven by non-genetic intraspecific trait change.

This article is part of the themed issue ‘Human influences on evolution, and the ecological and societal consequences’.
The eco-evolutionary impacts of domestication and agricultural practices on wild species
Authors: Turcotte Martin M. , Araki Hitoshi , Karp Daniel S. , Poveda Katja , Whitehead Susan R.
Published: December 2016

Agriculture is a dominant evolutionary force that drives the evolution of both domesticated and wild species. However, the various mechanisms of agriculture-induced evolution and their socio-ecological consequences are not often synthetically discussed. Here, we explore how agricultural practices and evolutionary changes in domesticated species cause evolution in wild species. We do so by examining three processes by which agriculture drives evolution. First, differences in the traits of domesticated species, compared with their wild ancestors, alter the selective environment and create opportunities for wild species to specialize. Second, selection caused by agricultural practices, including both those meant to maximize productivity and those meant to control pest species, can lead to pest adaptation. Third, agriculture can cause non-selective changes in patterns of gene flow in wild species. We review evidence for these processes and then discuss their ecological and sociological impacts. We finish by identifying important knowledge gaps and future directions related to the eco-evolutionary impacts of agriculture including their extent, how to prevent the detrimental evolution of wild species, and finally, how to use evolution to minimize the ecological impacts of agriculture.

This article is part of the themed issue ‘Human influences on evolution, and the ecological and societal consequences’.
Harvest-induced evolution: insights from aquatic and terrestrial systems
Authors: Kuparinen Anna , Festa-Bianchet Marco
Published: December 2016

Commercial and recreational harvests create selection pressures for fitness-related phenotypic traits that are partly under genetic control. Consequently, harvesting can drive evolution in targeted traits. However, the quantification of harvest-induced evolutionary life history and phenotypic changes is challenging, because both density-dependent feedback and environmental changes may also affect these changes through phenotypic plasticity. Here, we synthesize current knowledge and uncertainties on six key points: (i) whether or not harvest-induced evolution is happening, (ii) whether or not it is beneficial, (iii) how it shapes biological systems, (iv) how it could be avoided, (v) its importance relative to other drivers of phenotypic changes, and (vi) whether or not it should be explicitly accounted for in management. We do this by reviewing findings from aquatic systems exposed to fishing and terrestrial systems targeted by hunting. Evidence from aquatic systems emphasizes evolutionary effects on age and size at maturity, while in terrestrial systems changes are seen in weapon size and date of parturition. We suggest that while harvest-induced evolution is likely to occur and negatively affect populations, the rate of evolutionary changes and their ecological implications can be managed efficiently by simply reducing harvest intensity.

This article is part of the themed issue ‘Human influences on evolution, and the ecological and societal consequences'.
Effects of fragmentation on plant adaptation to urban environments
Authors: Dubois Jonathan , Cheptou Pierre-Olivier
Published: December 2016

Urban ecosystems are relatively recent and heavily human-altered terrestrial ecosystems with a surprisingly high diversity of animals, plants and other organisms. Urban habitats are also strongly fragmented and subject to higher temperatures, providing a compelling model for studying adaptation to global change.Crepis sancta(Asteraceae), an annual Mediterranean wasteland weed, occupies fragmented urban environments as well as certain unfragmented landscapes in southern France. We tested for shifts in dispersal, reproductive traits and size across a rural–urban gradient to learn whether and how selection may be driving changes in life history in urban and fragmented habitats. We specifically compared the structure of quantitative genetic variation and of neutral markers (microsatellites) between urban and rural and between fragmented and unfragmented habitats. We showed that fragmentation provides a better descriptor of trait variation than urbanizationper sefor dispersal traits. Fragmentation also affected reproductive traits and plant size though one rural population did conform to this scheme. Our study shows the role of fragmentation for dispersal traits shift in urban environments and a more complex pattern for other traits. We discuss the role of pollinator scarcity and an inhospitable matrix as drivers of adaptation.

This article is part of the themed issue ‘Human influences on evolution, and the ecological and societal consequences’.
Antibiotic resistance in the wild: an eco-evolutionary perspective
Authors: Hiltunen Teppo , Virta Marko , Laine Anna-Liisa
Published: December 2016

The legacy of the use and misuse of antibiotics in recent decades has left us with a global public health crisis: antibiotic-resistant bacteria are on the rise, making it harder to treat infections. At the same time, evolution of antibiotic resistance is probably the best-documented case of contemporary evolution. To date, research on antibiotic resistance has largely ignored the complexity of interactions that bacteria engage in. However, in natural populations, bacteria interact with other species; for example, competition and grazing are import interactions influencing bacterial population dynamics. Furthermore, antibiotic leakage to natural environments can radically alter bacterial communities. Overall, we argue that eco-evolutionary feedback loops in microbial communities can be modified by residual antibiotics and evolution of antibiotic resistance. The aim of this review is to connect some of the well-established key concepts in evolutionary biology and recent advances in the study of eco-evolutionary dynamics to research on antibiotic resistance. We also identify some key knowledge gaps related to eco-evolutionary dynamics of antibiotic resistance, and review some of the recent technical advantages in molecular microbiology that offer new opportunities for tackling these questions. Finally, we argue that using the full potential of evolutionary theory and active communication across the different fields is needed for solving this global crisis more efficiently.

This article is part of the themed issue ‘Human influences on evolution, and the ecological and societal consequences'.
Sublethal streptomycin concentrations and lytic bacteriophage together promote resistance evolution
Authors: Cairns Johannes , Becks Lutz , Jalasvuori Matti , Hiltunen Teppo
Published: December 2016

Sub-minimum inhibiting concentrations (sub-MICs) of antibiotics frequently occur in natural environments owing to wide-spread antibiotic leakage by human action. Even though the concentrations are very low, these sub-MICs have recently been shown to alter bacterial populations by selecting for antibiotic resistance and increasing the rate of adaptive evolution. However, studies are lacking on how these effects reverberate into key ecological interactions, such as bacteria–phage interactions. Previously, co-selection of bacteria by phages and antibiotic concentrations exceeding MICs has been hypothesized to decrease the rate of resistance evolution because of fitness costs associated with resistance mutations. By contrast, here we show that sub-MICs of the antibiotic streptomycin (Sm) increased the rate of phage resistance evolution, as well as causing extinction of the phage. Notably, Sm and the phage in combination also enhanced the evolution of Sm resistance compared with Sm alone. These observations demonstrate the potential of sub-MICs of antibiotics to impact key ecological interactions in microbial communities with evolutionary outcomes that can radically differ from those associated with high concentrations. Our findings also contribute to the understanding of ecological and evolutionary factors essential for the management of the antibiotic resistance problem.

This article is part of the themed issue ‘Human influences on evolution, and the ecological and societal consequences’.
Does eutrophication-driven evolution change aquatic ecosystems?
Authors: Alexander Timothy J. , Vonlanthen Pascal , Seehausen Ole
Published: December 2016

Eutrophication increases primary production and changes the relative abundance, taxonomic composition and spatial distribution of primary producers within an aquatic ecosystem. The changes in composition and location of resources alter the distribution and flow of energy and biomass throughout the food web. Changes in productivity also alter the physico-chemical environment, which has further effects on the biota. Such ecological changes influence the direction and strength of natural and sexual selection experienced by populations. Besides altering selection, they can also erode the habitat gradients and/or behavioural mechanisms that maintain ecological separation and reproductive isolation among species. Consequently, eutrophication of lakes commonly results in reduced ecological specialization as well as genetic and phenotypic homogenization among lakes and among niches within lakes. We argue that the associated loss in functional diversity and niche differentiation may lead to decreased carrying capacity and lower resource-use efficiency by consumers. We show that in central European whitefish species radiations, the functional diversity affected by eutrophication-induced speciation reversal correlates with community-wide trophic transfer efficiency (fisheries yield per unit phosphorus). We take this as an example of how evolutionary dynamics driven by anthropogenic environmental change can have lasting effects on biodiversity and ecosystem functioning.

This article is part of the themed issue ‘Human influences on evolution, and the ecological and societal consequences'.
Human drivers of ecological and evolutionary dynamics in emerging and disappearing infectious disease systems
Authors: Rogalski Mary A. , Gowler Camden D. , Shaw Clara L. , Hufbauer Ruth A. , Duffy Meghan A.
Published: December 2016

Humans have contributed to the increased frequency and severity of emerging infectious diseases, which pose a significant threat to wild and domestic species, as well as human health. This review examines major pathways by which humans influence parasitism by altering (co)evolutionary interactions between hosts and parasites on ecological timescales. There is still much to learn about these interactions, but a few well-studied cases show that humans influence disease emergence every step of the way. Human actions significantly increase dispersal of host, parasite and vector species, enabling greater frequency of infection in naive host populations and host switches. Very dense host populations resulting from urbanization and agriculture can drive the evolution of more virulent parasites and, in some cases, more resistant host populations. Human activities that reduce host genetic diversity or impose abiotic stress can impair the ability of hosts to adapt to disease threats. Further, evolutionary responses of hosts and parasites can thwart disease management and biocontrol efforts. Finally, in rare cases, humans influence evolution by eradicating an infectious disease. If we hope to fully understand the factors driving disease emergence and potentially control these epidemics we must consider the widespread influence of humans on host and parasite evolutionary trajectories.

This article is part of the themed issue ‘Human influences on evolution, and the ecological and societal consequences’.
Resistance in persisting bat populations after white-nose syndrome invasion
Authors: Langwig Kate E. , Hoyt Joseph R. , Parise Katy L. , Frick Winifred F. , Foster Jeffrey T. , Kilpatrick A. Marm
Published: December 2016

Increases in anthropogenic movement have led to a rise in pathogen introductions and the emergence of infectious diseases in naive host communities worldwide. We combined empirical data and mathematical models to examine changes in disease dynamics in little brown bat (
Myotis lucifugus
) populations following the introduction of the emerging fungal pathogen
Pseudogymnoascus destructans
, which causes the disease white-nose syndrome. We found that infection intensity was much lower in persisting populations than in declining populations where the fungus has recently invaded. Fitted models indicate that this is most consistent with a reduction in the growth rate of the pathogen when fungal loads become high. The data are inconsistent with the evolution of tolerance or an overall reduced pathogen growth rate that might be caused by environmental factors. The existence of resistance in some persisting populations of little brown bats offers a glimmer of hope that a precipitously declining species will persist in the face of this deadly pathogen.

This article is part of the themed issue ‘Human influences on evolution, and the ecological and societal consequences’.
Life history trade-offs, the intensity of competition, and coexistence in novel and evolving communities under climate change
Authors: Lancaster Lesley T. , Morrison Gavin , Fitt Robert N.
Published: December 2016

The consequences of climate change for local biodiversity are little understood in process or mechanism, but these changes are likely to reflect both changing regional species pools and changing competitive interactions. Previous empirical work largely supports the idea that competition will intensify under climate change, promoting competitive exclusions and local extinctions, while theory and conceptual work indicate that relaxed competition may in fact buffer communities from biodiversity losses that are typically witnessed at broader spatial scales. In this review, we apply life history theory to understand the conditions under which these alternative scenarios may play out in the context of a range-shifting biota undergoing rapid evolutionary and environmental change, and at both leading-edge and trailing-edge communities. We conclude that, in general, warming temperatures are likely to reduce life history variation among competitors, intensifying competition in both established and novel communities. However, longer growing seasons, severe environmental stress and increased climatic variability associated with climate change may buffer these communities against intensified competition. The role of life history plasticity and evolution has been previously underappreciated in community ecology, but may hold the key to understanding changing species interactions and local biodiversity under changing climates.

This article is part of the themed issue ‘Human influences on evolution, and the ecological and societal consequences’.
MtrA is an essential regulator that coordinates antibiotic production and sporulation inStreptomycesspecies
Authors: Som Nicolle F. , Heine Daniel , Munnoch John T. , Holmes Neil A. , Knowles Felicity , Chandra Govind , Seipke Ryan F. , Hoskisson Paul A. , Wilkinson Barrie , Hutchings Matthew I.
Published: December 2016

Streptomycesbacteria make numerous secondary metabolites, including half of all known antibiotics. Understanding the global regulation of secondary metabolism is important because mostStreptomycesnatural products are not made under laboratory conditions and unlocking ‘cryptic’ biosynthetic gene clusters (BGCs) is a major focus for natural product discovery. Production is coordinated with sporulation but the regulators that coordinate development with antibiotic biosynthesis are largely unknown. Here we characterise a highly conserved actinobacterial response regulator called MtrA in antibiotic-producingStreptomycesspecies. We show that MtrA is an essential global regulator of secondary metabolism that directly activates antibiotic production in inS. coelicolorandS. venezuelae. MtrA also controls key developmental genes required for DNA replication and cell division and we propose that MtrA is the missing link that coordinates secondary metabolism with development inStreptomycesspecies.
Cushing’s Syndrome mutant PKAL205Rexhibits altered substrate specificity
Authors: Lubner Joshua M. , Dodge-Kafka Kimberly L. , Carlson Cathrine R. , Church George M. , Chou Michael F. , Schwartz Daniel
Published: December 2016

The PKAL205Rhotspot mutation has been implicated in Cushing’s Syndrome through hyperactive gain-of-function PKA signaling, however its influence on substrate specificity has not been investigated. Here, we employ the Proteomic Peptide Library (ProPeL) approach to create high-resolution models for PKAWTand PKAL205Rsubstrate specificity. We reveal that the L205R mutation reduces canonical hydrophobic preference at the substrate P+1 position, and increases acidic preference in downstream positions. Using these models, we designed peptide substrates that exhibit altered selectivity for specific PKA variants, and demonstrate the feasibility of selective PKAL205Rloss-of-function signaling. Through these results, we suggest that substrate rewiring may contribute to Cushing’s Syndrome disease etiology, and introduce a powerful new paradigm for investigating mutation-induced kinase substrate rewiring in human disease.
Cross-tissue integration of genetic and epigenetic data offers insight into autism spectrum disorder
Authors: Andrews Shan V. , Ellis Shannon E. , Bakulski Kelly M. , Sheppard Brooke , Croen Lisa A. , Hertz-Picciotto Irva , Newschaffer Craig J. , Feinberg Andrew P. , Arking Dan E. , Ladd-Acosta Christine , Fallin M. Daniele
Published: December 2016

Integration of emerging epigenetic information with Autism Spectrum Disorder (ASD) genetic results may elucidate functional insights not possible via either type of information in isolation. We use genotype and DNA methylation (DNAm) data from cord blood and peripheral blood to identify SNPs associated with DNA methylation (meQTL lists) and additionally use publicly available fetal brain and lung meQTL lists to assess enrichment of ASD GWAS results for tissue-specific meQTLs. ASD-associated SNPs are enriched for fetal brain (OR = 3.55; p < 0.001) and peripheral blood meQTLs (OR = 1.58; p < 0.001). The CpG targets of ASD meQTLs across cord, blood, and brain tissues are enriched for immune-related pathways, consistent with other expression and DNAm results in ASD, and reveal pathways not implicated by genetic findings. This joint analysis of genotype and DNAm demonstrates the potential of both brain and blood-based DNAm for insights into ASD and psychiatric phenotypes more broadly.
Splice Expression Variation Analysis (SEVA) for Inter-tumor Heterogeneity of Gene Isoform Usage in Cancer
Authors: Afsari Bahman , Guo Theresa , Considine Michael , Florea Liliana , Kagohara Luciane T. , Stein-O’Brien Genevieve L. , Kelley Dylan , Flam Emily , Zambo Kristina D. , Ha Patrick K. , Geman Donald , Ochs Michael F. , Califano Joseph A. , Gaykalova Daria A. , Favorov Alexander V. , Fertig Elana J.
Published: December 2016

Motivation

Current bioinformatics methods to detect changes in gene isoform usage in distinct phenotypes compare the relative expected isoform usage in phenotypes. These statistics model differences in isoform usage in normal tissues, which have stable regulation of gene splicing. Pathological conditions, such as cancer, can have broken regulation of splicing that increases the heterogeneity of the expression of splice variants. Inferring events with such differential heterogeneity in gene isoform usage requires new statistical approaches.

Results

We introduce Splice Expression Variability Analysis (SEVA) to model increased heterogeneity of splice variant usage between conditions (e.g., tumor and normal samples). SEVA uses a rank-based multivariate statistic that compares the variability of junction expression profiles within one condition to the variability within another. Simulated data show that SEVA is unique in modeling heterogeneity of gene isoform usage, and benchmark SEVA’s performance against EBSeq, DiffSplice, and rMATS that model differential isoform usage instead of heterogeneity. We confirm the accuracy of SEVAin identifying known splice variants in head and neck cancer and perform cross-study validation of novel splice variants. A novel comparison of splice variant heterogeneity between subtypes of head and neck cancer demonstrated unanticipated similarity between the heterogeneity of gene isoform usage in HPV-positive and HPV-negative subtypes and anticipated increased heterogeneity among HPV-negative samples with mutations in genes that regulate the splice variant machinery.

Conclusion

These results show that SEVA accurately models differential heterogeneity of gene isoform usage from RNA-seq data.

Availability

SEVA is implemented in the R/Bioconductor package GSReg.

Contact

bahman@jhu.edu,favorov@sensi.org,ejfertig@jhmi.edu
Spatiotemporal characterization of the neural correlates of outcome valence and surprise during reward learning in humans
Authors: Fouragnan Elsa , Queirazza Filippo , Retzler Chris , Mullinger Karen J. , Philiastides Marios G.
Published: December 2016

Reward learning depends on accurate reward associations with potential choices. Two separate outcome dimensions, namely the valence (positive or negative) and surprise (the absolute degree of deviation from expectations) of an outcome are thought to subserve adaptive decision-making and learning, however their neural correlates and relative contribution to learning remain debated. Here, we coupled single-trial analyses of electroencephalography with simultaneously acquired fMRI, while participants performed a probabilistic reversal-learning task, to offer evidence of temporally overlapping but largely distinct spatial representations of outcome valence and surprise in the human brain. Electrophysiological variability in outcome valence correlated with activity in regions of the human reward network promoting approach or avoidance learning. Variability in outcome surprise correlated primarily with activity in regions of the human attentional network controlling the speed of learning. Crucially, despite the largely separate spatial extend of these representations we also found a linear superposition of the two outcome dimensions in a smaller network encompassing visuo-mnemonic and reward areas. This spatiotemporal overlap was uniquely exposed by our EEG-informed fMRI approach. Activity in this network was further predictive of stimulus value updating indicating a comparable contribution of both signals to reward learning.
Revealing compartmentalised membrane diffusion in living cells with interferometric scattering microscopy
Authors: de Wit G. , Albrecht D. , Ewers H. , Kukura P.
Published: December 2016

Single-particle tracking is a powerful tool for studying single molecule behaviour involving plasma membrane-associated events in cells. Here, we show that interferometric scattering microscopy (iSCAT) combined with gold nanoparticle labeling can be used to follow the motion of membrane proteins in the plasma membrane of live cultured mammalian cell lines and hippocampal neurons. The unique combination of microsecond temporal resolution and nanometer spatial precision reveals signatures of a compartmentalised plasma membrane in neurons.
The dynamic three-dimensional organization of the diploid yeast genome
Authors: Kim Seungsoo , Liachko Ivan , Brickner Donna G , Cook Kate , Noble William S , Brickner Jason H , Shendure Jay , Dunham Maitreya J
Published: December 2016

The budding yeast Saccharomyces cerevisiae is a long-standing model for the three-dimensional organization of eukaryotic genomes. Even in this well-studied model, it is unclear how homolog pairing in diploids and environment-induced gene relocalization influence overall genome organization. Here, we performed high-throughput chromosome conformation capture on diverged Saccharomyces hybrid diploids to obtain the first global view of chromosome conformation in diploid yeasts. After controlling for the Rabl-like orientation, we observe significant homolog proximity that increased in saturated culture conditions. Surprisingly, we observe a localized increase in homologous interactions between the HAS1 alleles specifically under galactose induction and saturated growth, mediated by association with nuclear pore complexes at the nuclear periphery. Together, these results reveal that the diploid yeast genome has a dynamic and complex 3D organization.
The innate immune systems of malacostracan crustaceans exhibit both conserved and evolutionarily distinct components
Authors: Lai Alvina G. , Aboobaker A. Aziz
Published: December 2016

Growing demands for aquatic sources of animal proteins have attracted significant investments in aquaculture research in recent years. The crustacean aquaculture industry has undergone substantial growth to accommodate a rising global demand, however such large-scale production is susceptible to pathogen-mediated destruction. It is clear that a thorough understanding of the crustacean innate immune system is imperative for future research into combating current and future pathogens of the main food crop species. Through a comparative genomics approach utilising extant data from 55 species, we describe the innate immune system of crustaceans from the Malacostraca class. We identify 7407 malacostracan genes from 39 gene families implicated in different aspects of host defence and demonstrate dynamic evolution of innate immunity components within this group. Malacostracans have achieved flexibility in recognising infectious agents through divergent evolution and expansion of pathogen recognition receptors genes. Antiviral RNAi, Toll and JAK-STAT signal transduction pathways have remained conserved within Malacostraca, although the Imd pathway appears to lack several key components. Immune effectors such as the antimicrobial peptides (AMPs) have unique evolutionary profiles, with many malacostracan AMPs not found in other arthropod groups. Lastly, we describe four putative novel immune gene families, characterised by distinct protein domains, potentially representing important evolutionary novelties of the malacostracan immune system.
Structural visualization of the p53/RNA polymerase II assembly
Authors: Singh Sameer K. , Qiao Zhen , Song Lihua , Jani Vijay , Rice William , Eng Edward , Coleman Robert A. , Liu Wei-Li
Published: December 2016

The master tumor suppressor p53 activates transcription in response to various cellular stresses in part by facilitating recruitment of the transcription machinery to DNA. Recent studies have documented a direct yet poorly characterized interaction between p53 and RNA polymerase II (Pol II). Therefore, we dissected the human p53/Pol II interaction via single-particle cryo-electron microscopy, structural docking, and biochemical analyses. This study reveals that p53 binds Pol II via the Rpb1 and Rpb2 subunits, bridging the DNA-binding cleft of Pol II proximal to the upstream DNA entry site. In addition, the key DNA-binding surface of p53, frequently disrupted in various cancers, remains exposed within the assembly. Furthermore, the p53/Pol II cocomplex displays a closed conformation as defined by the position of the Pol II clamp domain. Notably, the interaction of p53 and Pol II leads to increased Pol II elongation activity. These findings indicate that p53 may structurally regulate DNA-binding functions of Pol II via the clamp domain, thereby providing insights into p53-regulated Pol II transcription.
A heuristic approach to evaluateperiinteractionsversusintermolecular interactions in an overcrowded naphthalene
Authors: Sarkar Sounak , Row Tayur N. Guru
Published: December 2016

Octachloronaphthalene (OCN), a serious environmental pollutant, has been investigated by charge density analysis to unravel several unexplored factors responsible for steric overcrowding. The topological features of the enigmaticperiinteractions contributing to steric overcrowding are qualified and quantified from experimental and theoretical charge-density studies. A new facet in the fundamental understanding ofperiinteractions is revealed by NCI (non-covalent interaction) analysis. The potential role of these interactions in deforming the molecular geometry and subsequent effect on aromaticity are substantiated from NICS (Nuclear Independent Chemical Shift) and QTAIM (Quantum Theory of Atoms in Molecules) calculations. The eye-catching dissimilarity in the out-of-plane twisting of OCN renders the molecule in an asymmetric geometry in the crystalline phase compared with symmetric geometry in the optimized solvated phase. This is uniquely characterized by their molecular electrostatic potential (MESP), respectively, and is explained in terms of conflict between two opposing forces –periinteractions, and symbiotic intermolecular Cl...Cl and Cl...π contacts.
New 1:1 and 2:1 salts in the `DL-norvaline–maleic acid' system as an example of assembling various crystal structures from similar supramolecular building blocks
Authors: Arkhipov Sergey G. , Losev Evgeniy A. , Boldyreva Elena V.
Published: December 2016

Molecular salts and cocrystals of amino acids have potential applications as molecular materials with nonlinear optical, ferroelectric, piezoelectric, and other various target physical properties. The wide choice of amino acids and coformers makes it possible to design various crystal structures. The amino acid–maleic acid system provides a perfect example of a rich variety of crystal structures with different stoichiometries, symmetries and packing motifs built from the molecular building blocks, which are either exactly the same, or differ merely by protonation or as optical isomers. The present paper reports the crystal structures of two new salts of the DL-norvaline–maleic acid system with 1:1 and 2:1 stoichiometries, namely DL-norvalinium hydrogen maleate, C5H12NO2+·C4H3O4−, (I), and DL-norvalinium hydrogen maleate–DL-norvaline, C5H12NO2+·C4H3O4−·C5H11NO2, (II). These are the first examples of molecular salts of DL-norvaline with an organic anion. The crystal structure of (I) has the sameC22(12) structure-forming motif which is common for hydrogen maleates of amino acids. The structure of (II) has dimeric cations. Of special interest is that the single crystals of (I) which are originally formed on crystallization from aqueous solution transform into single crystals of (II) if stored in the mother liquor for several hours.
Disorder of the dimeric TCNQ–TCNQ unit in the crystal structure of [Ni(bpy)3]2(TCNQ–TCNQ)(TCNQ)2·6H2O (TCNQ is 7,7,8,8-tetracyanoquinodimethane)
Authors: Černák Juraj , Kuchár Juraj , Hegedüs Michal
Published: December 2016

Crystallization from an aqueous methanol system composed of Ni(NO3)2, 2,2′-bipyridine (bpy) and LiTCNQ (TCNQ is 7,7,8,8-tetracyanoquinodimethane) in a 1:3:2 molar ratio yielded single crystals of bis[tris(2,2′-bipyridine-κ2N,N′)nickel(II)] bis(7,7,8,8-tetracyanoquinodimethane radical anion) bi[7,7,8,8-tetracyanoquinodimethanide] hexahydrate, [Ni(C10H8N2)3]2(C24H8N8)(C12H4N4)2·6H2O or [Ni(bpy)3]2(TCNQ–TCNQ)(TCNQ)2·6H2O. The crystal structure comprises [Ni(bpy)3]2+complex cations, two centrosymmetric crystallographically independent TCNQ·−anion radicals with π-stacked exo groups, and an additional dimeric TCNQ–TCNQ unit which comprises 75.3 (9)% of a σ-dimerized (TCNQ–TCNQ)2−dianion and 24.7 (9)% of two TCNQ·−anion radicals with tightly π-stacked exo groups. The title complex represents the first example of an NiIIcomplex containing a σ-dimerized (TCNQ–TCNQ)2−dianion. Disordered solvent water molecules present in the crystal structure participate in hydrogen-bonding interactions.
Preparation and performances of coated and aluminous entry boards with water-soluble resins for PCB drilling
Authors: Zhou Hu , Yu Bin , Li Ning , Zhou Jie , Luo Xiaoyang , Tang Jialin , Qin Xianzhi
Published: December 2016

Purpose

This paper aims to provide a new drilling entry board for printed circuit board (PCB) process, superior in heat dissipation, lubrication, water solubility and hole location accuracy, achieving an excellent drilling process.

Design/methodology/approach

Using a mixture of polyethylene glycol (PEG) and water-soluble adhesives as hydrosoluble, endothermic and lubricant resins and aluminum foils as baseplates, a series of coated and aluminous entry boards (CABs) for PCB drilling was successfully prepared. The surface appearance of the entry boards was observed clearly by scanning electron microscopy (SEM). The endothermic and lubricant effects of the resins applied on the CABs was characterized by differential scanning calorimetry (DSC) and their water solubility was tested in the normal-temperature water (25°C). Moreover, the CABs’ good drilling properties were tested when they were used for PCB drilling.

Findings

The SEM analysis showed that the surfaces of the resin layers coated on the CABs whose coating thicknesses were less than 80 μm were smoother and flatter, which could improve hole location accuracy and reduce drill breakage ratio. By virtue of DSC, the endothermic and lubricant effects of the CABs were proven. The fusion of PEG in the resin layers could absorb the heat produced by drilling, restrain the temperature of the drill bit and hole rising and lubricate the drill bit efficiently when a hole was being drilled, which could achieve high-quality holes with good production efficiency. The water-soluble test showed that the prepared CABs had excellent water solubility at normal temperature, enabling the resin left on the hole walls and in the flute of the drill bit to be washed away easily and thereby improving the drilling efficiency and quality. The drilling tests showed that the increase in the thickness of the CABs’ coating could improve the hole location accuracy and alleviate the bit wear. In addition, the suitable coating thickness could ensure the firm adhering of the resin coating the aluminum foil, effectively avoid drill intertwist and prevent the resin debris from blocking the drilled holes on the surface of the entry board, which could hinder chip removal, resulting in poor hole wall quality and drill breakage.

Originality/value

This paper has a remarkably high industrial practicality in the PCB manufacture process.
The tool-wear characteristics of flexible printed circuit board micro-drilling and its influence on micro-hole quality
Authors: Zheng Lijuan , Wang Chengyong , Zhang Xin , Huang Xin , Song Yuexian , Wang Kefeng , Zhang Lunqiang
Published: December 2016

Purpose

Micro-holes are drilled and plated in flexible printed circuit boards (FPCs) for connecting circuits from different layers. More holes, with diameters smaller than 0.3 mm, are required to be drilled in smaller areas with flexible circuits’ miniaturization. The micro-hole quality of micro-drilling is one of the biggest issues of the flexible circuit manufacturers’ production. However, it is not easy to control the quality of micro-holes. The purpose of this study was to conduct research on the tool wear characteristics of FPC drilling process and its influence on micro-hole quality to improve the micro-hole quality of FPC.

Design/methodology/approach

The tool-wear characteristics of micro-drills after FPC drilling were observed. The influence of spindle speed, feed rate, number of drilled holes and entry board materials on tool-wear was analyzed. The hole qualities of FPC micro-drilling were measured and observed. The relationship between tool-wear and hole quality was analyzed.

Findings

The result showed that the tool-wear characteristics of FPC micro-drilling was similar to the tool-wear characteristics of rigid printed circuit board (RPC) micro-drilling. Abrasive wear occurred on both the main cutting edges and the chisel edges of micro-drills, even though there was no glass fiber reinforcing the cloth inside FPC. Resin adhesion was observed on the chisel edge. The influence of feed and number of drilled holes on tool-wear was significant. Tool-wear significantly influences the hole quality of FPC. Tool-wear will largely decrease the hole position accuracy of FPC micro-holes. Tool-wear will increase the thickness of PI nail heads and the height of exit burrs. Fracture was the main difference between tool wear of FPC and RPC micro-drilling. Resin adhesion of RPC was much more severe than FPC micro-drilling. Increasing the spindle speed properly may improve tool life and hole quality.

Originality/value

The technology and manufacturing of FPC has been little investigated. Research on micro-drilling FPC and research data is lacking so far. The micro-hole quality directly affects the reliability of FPC. Thus, improving the micro-hole quality of FPC is very important.
Non-equidistant GM(1,1) model based on GCHM_WBO and its application in corrosion rate prediction
Authors: Zhi Yuanjie , Fu Dongmei , Wang Hanling
Published: December 2016

Purpose

The purpose of this paper is to present a new model which combines the non-equidistant GM(1,1) model with GCHM_WBO (generalized contra-harmonic mean (GCHM); weakening buffer operator (WBO)). The authors use the model to solve the deadlock that for a large number of non-equidistant corrosion rate, it is difficult to establish a reasonable prediction model and improve the prediction accuracy.

Design/methodology/approach

This research consists of three parts: non-equidistant GM(1,1) model, GCHM_WBO operator, and the optimization of morphing parameter (contained in GCHM, control the intensity of the weakening operator). The methodology is explained as follows. First, the authors built a non-equidistant GM(1,1) model with GCHM_WBO weakened data, of which morphing parameter was randomly selected. Next, the authors calculated the error between prediction data of model and the real data, and adjusted the morphing parameter according to the error and property of GCHM. Then, the authors generated a new non-equidistant GM(1,1) based on new morphing parameter, and repeated the previous step until the termination condition was satisfied. Finally, the model with appropriate morphing parameter was used to implement the prediction of new data.

Findings

This paper finds a property of GCHM, which is a monotonic increasing function of morphing parameter in some specific conditions. Based on the property and the fixed point axiom of WBO, an algorithm was designed to search an appropriate morphing parameter. The appropriate morphing parameter was implemented for the purpose of improving the accuracy of the model. The model was applied to predict the corrosion rate of six steels at Guangzhou experimental station. The results showed that the proposed method can get more accuracy in prediction capability compared to the models with the original data and AWBO weakened data. The method is applicable to long-term forecasts in case of data scarcity.

Practical implications

Corrosion will cause huge economic loss to a country; therefore, it is important to judge the remaining useful life of a material or equipment; the foundation for judgement of which is the prediction of material corrosion rate. However, the prediction of corrosion rate is very difficult because of corrosion data’s features, such as small sample size, non-equidistant, etc. The proposed method can be used to implement long-term forecast of corrosion data with only one sample and non-equidistant samples.

Originality/value

This paper presented a model which combines the non-equidistant GM(1,1) model with GCHM_WBO to handle the problem of long-term forecasting of corrosion data. In the modelling process, the proposed morphing parameter searched through algorithm can improve the prediction accuracy of the model. Therefore, the model can provide effective and reliable result when data are of a small sample size and non-equidistant.
A literature-based intervention for women prisoners: preliminary findings
Authors: Billington Josie , Longden Eleanor , Robinson Jude
Published: December 2016

Purpose

The purpose of this paper is to investigate whether Shared Reading (SR), a specific literature-based intervention, is transposable to a prison context and whether mental health benefits identified in other custodial and non-custodial settings were reported by women prisoners.

Design/methodology/approach

In all, 35 participants were recruited within an all-female maximum security prison and attended one of two weekly reading groups. Qualitative data were collected through researcher observation of the reading groups; interviews and focus group discussions with participants and prison staff; interviews with the project worker leading the reading groups; and a review of records kept by the latter during group sessions.

Findings

Attendance rates were good, with nearly half of the participants voluntarily present at =60 per cent of sessions. Two intrinsic psychological processes associated with the SR experience were provisionally identified, “memory and continuities” and “mentalisation”, both of which have therapeutic implications for the treatment of conditions like depression and personality disorder.

Research limitations/implications

Limitations included the small sample, lack of control for confounding variables, and constraints imposed on data collection by the custodial setting.

Originality/value

Although more controlled research is required, the findings indicate that women prisoners will voluntarily engage with SR if given appropriate support, and that the intervention has potential to augment psychological processes that are associated with increased well-being.
Islamic banking presence and economic growth in Southeast Asia
Authors: Lebdaoui Hind , Wild Joerg
Published: December 2016

Purpose

The purpose of this study is to empirically assess the relationship between Islamic banking presence in Southeast Asian countries and the economic growth.

Design/methodology/approach

The presence of Islamic banks is measured by the ratio of Islamic to conventional banking assets as well as the ratio of deposits of Islamic to conventional banking. This study starts by checking the presence of cointegration using Pedroni’s and Westerlund’s specifications; short- and long-run dynamics are further analyzed with the panel autoregressive distributed lag model (ARDL)-based estimators: pooled mean group (PMG), mean group (MG) and dynamic fixed effect (DFE). Furthermore, a two-stage regression [two-stage least squares (2SLS)] was constructed to measure the sensitivity of economic growth to the Islamic banking presence. Quarterly data from Southeast Asian countries cover the period between 2000Q1 and 2012Q4.

Findings

A long-run relationship is evident between economic growth and the Islamic banking presence in the selected region, but not in the short run. Furthermore, the Muslim population share in a given country plays a positive and statistically significant role in fueling the contribution of Islamic banking share in the financial sector on the economic growth.

Social implications

The results of this study show that Sharia-compliant banks succeeded in mobilizing additional resources for the financial sector, which may increase the stability of the banking system and the efficiency of the whole banking sector. The authors believe that the inclusion of Islamic banking products in the financial systems will, along with the diversification effect, stimulate financial deepening and, therefore, improve the financial stability in the countries under investigation in particular, and all countries with significant Muslim population in general.

Originality/value

This study empirically assesses the contribution of Islamic banking presence on the economic growth with a focus on Southeast Asia, as this region encompasses the most developed and experienced institutions in the field of Islamic finance. Error correction-based models such as PMG, MG and DFE lend itself to the analysis of the panel data. This study also uses the instrument-based 2SLS to cope with the endogeneity problem between the real and financial sectors.
Comparison of ethical and conventional portfolios with second-order stochastic dominance efficiency test
Authors: Tas Oktay , Tokmakcioglu Kaya , Ugurlu Umut , Isiker Murat
Published: December 2016

Purpose

This paper aims to compare two groups of stocks to analyze the efficiency of an ethical portfolio in comparison with a conventional portfolio.

Design/methodology/approach

Efficiency test by second-order stochastic dominance (SSD) approach is applied on two groups, which consist of 12 stocks. Ethical portfolio is chosen from the stocks complying with the participation banking rules. Conventional portfolio is selected from Borsa Istanbul (BIST) with choosing the corresponding stocks for each ethical stock according to the sector and market capitalization. All the stocks of both groups are pairwise SSD compared.

Findings

Both groups of 12 stocks are inefficient portfolios; however, a group of 7 stocks constitute an efficient ethical portfolio with the total weight of 50.82 per cent among the set of 12 ethical stocks. On the other hand, a group of 6 stocks constitute an efficient conventional portfolio, with the total weight of 45.16 per cent among the set of 12 conventional stocks. By pairwise SSD comparison of corresponding stocks from both groups, despite none of the conventional stocks dominate ethical stocks, four ethical stocks dominated the conventional ones.

Originality/value

Back-testing and comparison with benchmark BIST 100 Index have been done for the selected portfolios. According to back-testing results, groups of SSD efficient stocks outperformed the groups, from which they were selected. Furthermore, both SSD efficient portfolios have higher returns than benchmark index, BIST 100.