bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatial spread ofWolbachiainRhagoletis cerasipopulations
Authors: Bakovic Vid , Schebeck Martin , Telschow Arndt , Stauffer Christian , Schuler Hannes
Published: May 2018

The bacterial endosymbiontWolbachiahas been used to control insect pests owing to its ability to manipulate their life history and suppress infectious diseases. Therefore, knowledge onWolbachiadynamics in natural populations is fundamental. The European cherry fruit fly,Rhagoletis cerasi, is infected with theWolbachiastrainwCer2, mainly present in southern and central European populations, and is currently spreading intowCer2-uninfected populations driven by high unidirectional cytoplasmic incompatibility. Here, we describe the distribution ofwCer2 along two transition zones where the infection is spreading intowCer2-uninfectedR. cerasipopulations. Fine-scale sampling of 19 populations in the Czech Republic showed a smooth decrease ofwCer2 frequency from south to north within a distance of less than 20 km. Sampling of 12 Hungarian populations, however, showed a sharp decline ofwCer2 infection frequency within a few kilometres. We fitted a standard wave equation to our empirical data and estimated aWolbachiawave speed of 1.9 km yr−1in the Czech Republic and 1.0 km yr−1in Hungary. Considering the univoltine life cycle and limited dispersal ability ofR. cerasi, our study highlights a rapidWolbachiaspread in natural host populations.
Charles Blagden's diary: Information management and British science in the eighteenth century
Authors: Wills Hannah
Published: May 2018

This paper examines the diary of Charles Blagden, physician and secretary of the Royal Society between 1784 and 1797. It argues that the form and content of Blagden's diary developed in response to manuscript genres from a variety of contexts, including the medical training that Blagden undertook at the start of his career, the genre of the commonplace book, and contemporary travel narratives. Blagden was interested in the workings of memory and in the association of ideas. This paper reveals the diary's nature as an aid to memory and an information management tool. It argues that the diary assisted Blagden's attempts to secure the patronage of key figures in the eighteenth-century scientific world, including Joseph Banks, the Royal Society and a London-based network of aristocratic women. In exploring the development of the diary, the paper uncovers the role of a material object in aiding the management of patronage relationships central to the career of a significant but little-studied secretary of the Royal Society.
Sequence analysis and structure prediction of ABHD16A and the roles of the ABHD family members in human disease
Authors: Xu Jun , Gu Weizhen , Ji Kai , Xu Zhao , Zhu Haihua , Zheng Wenming
Published: May 2018

Abhydrolase domain containing 16A (ABHD16A) is a member of the α/β hydrolase domain-containing (ABHD) protein family and is expressed in a variety of animal cells. Studies have shown that ABHD16A has acylglycerol lipase and phosphatidylserine lipase activities. Its gene location in the main histocompatibility complex (MHC) III gene cluster suggests that this protein may participate in the immunomodulation of the body. The results of studies investigating nearly 20 species of ABHDs reveal that the ABHD proteins are key factors in metabolic regulation and disease occurrence and development. In this paper, we summarize the related progress regarding the function of ABHD16A and other ABHD proteins. A prediction of the active sites and structural domains of ABHD16A and an analysis of the amino acid sites are included. Moreover, we analysed the amino acid sequences of the ABHD16A molecules in different species and provide an overview of the related functions and diseases associated with these proteins. The functions and diseases related to ABHD are systematically summarized and highlighted. Future research directions for studies investigating the functions and mechanisms of these proteins are also suggested. Further studies investigating the function of ABHD proteins may further confirm their positions as important determinants of lipid metabolism and related diseases.
Topographic mapping of the interfaces between human and aquatic mosquito habitats to enable barrier targeting of interventions against malaria vectors
Authors: Mwakalinga Victoria M. , Sartorius Benn K. D. , Limwagu Alex J. , Mlacha Yeromin P. , Msellemu Daniel F. , Chaki Prosper P. , Govella Nicodem J. , Coetzee Maureen , Dongus Stefan , Killeen Gerry F.
Published: May 2018

Geophysical topographic metrics of local water accumulation potential are freely available and have long been known as high-resolution predictors of where aquatic habitats for immature
Anopheles
mosquitoes are most abundant, resulting in elevated densities of adult malaria vectors and human infection burden. Using existing entomological and epidemiological survey data, here we illustrate how topography can also be used to map out the interfaces between wet, unoccupied valleys and dry, densely populated uplands, where malaria vector densities and infection risk are focally exacerbated. These topographically identifiable geophysical boundaries experience disproportionately high vector densities and malaria transmission risk, because this is where
Anopheles
mosquitoes first encounter humans when they search for blood after emerging or ovipositing in the valleys. Geophysical topographic indicators accounted for 67% of variance for vector density but for only 43% for infection prevalence, so they could enable very selective targeting of interventions against the former but not the latter (targeting ratios of 5.7 versus 1.5 to 1, respectively). So, in addition to being useful for targeting larval source management to wet valleys, geophysical topographic indicators may also be used to selectively target adult
Anopheles
mosquitoes with insecticidal residual sprays, fencing, vapour emanators or space sprays to barrier areas along their fringes.
Urban regulatory focus: a new concept linking city size to human behaviour
Authors: Ross Guy M. , Portugali Juval
Published: May 2018

Why do people in big cities behave differently to those living in small cities? To answer this question, in this paper a new concept of urban dynamics is presented that links city size to human behaviour. The concept has its origins in regulatory focus theory. According to the theory, goal-directed behaviour is regulated by two motivational systems, promotion and prevention. Individuals motivated by promotion goals (growth, accomplishment) focus on winning and tend to take risks, whereas those driven by prevention goals (safety, security) focus on not losing and try to avoid risk. Here we elaborate on the existing literature by linking the theory to the urban context. In our conceptualization, cities are powerful regulatory systems, and as such they impinge upon the way people regulate themselves in the urban space. Evidence from signal detection analysis is provided that supports this concept. The experience of a big-city context intensified both promotion-focused behaviour (a risky bias) for promotion-focused participants and prevention-focused behaviour (a conservative bias) for prevention-focused participants. The experience of a small-city context encouraged the opposite behavioural pattern in both cases. These findings suggest that the urban environment can influence the regulatory focus strategies of an individual in a way that cannot simply be explained by their personal regulatory focus. Specifically, the likelihood of one's behaving in a promotion- or prevention-oriented manner is dependent both on one's chronic regulatory focus and also on the urban context in which one lives. Based on this, we maintain that vibrant cities with a large population and a fast pace of life encourage extreme and polarized behaviours, whereas cities with a smaller population and a slower pace of life encourage more moderate and less polarized behavioural responses, which may explain why people in big cities take more risks, do more business, produce and spend more, and even walk faster.
Improvement of the selectivity of isophorone hydrogenation by Lewis acids
Authors: Hou Yucui , Ren Shuhang , Niu Muge , Wu Weize
Published: May 2018

The selective hydrogenation of isophorone (3,5,5-trimethyl-2- cyclohexen-1-one) to produce 3,3,5-trimethylcyclohexanone (TMCH), an important organic solvent and pharmaceutical intermediate, is of significance in industry. However, the over-hydrogenation to produce the by-product 3,3,5-trimethylcyclohexanol causes issues. Up to now, it is still a challenge to hydrogenate isophorone to TMCH with high selectivity. In this work, we found that Lewis acids could inhibit the hydrogenation of C=O bond on isophorone, thus greatly improving the selectivity towards TMCH. In addition, added solvents like supercritical CO
2
also had a positive impact on the selectivity. Both the conversion and selectivity could be increased to more than 99% when suitable Lewis acid and solvent were employed. Nevertheless, Lewis acid also exhibited some inhibition on the hydrogenation of the C=C bond of isophorone. Hence, a relatively weak Lewis acid, ZnCl
2
, is suitable for the selective hydrogenation.
Evidence that metallic proxies are unsuitable for assessing the mechanics of microwear formation and a new theory of the meaning of microwear
Authors: van Casteren Adam , Lucas Peter W. , Strait David S. , Michael Shaji , Bierwisch Nick , Schwarzer Norbert , Al-Fadhalah Khaled J. , Almusallam Abdulwahab S. , Thai Lidia A. , Saji Sreeja , Shekeban Ali , Swain Michael V.
Published: May 2018

Mammalian tooth wear research reveals contrasting patterns seemingly linked to diet: irregularly pitted enamel surfaces, possibly from consuming hard seeds, versus roughly aligned linearly grooved surfaces, associated with eating tough leaves. These patterns are important for assigning diet to fossils, including hominins. However, experiments establishing conditions necessary for such damage challenge this paradigm. Lucas
et al
. (Lucas
et al
. 2013
J. R. Soc. Interface
10
, 20120923. (
doi:10.1098/rsif.2012.0923
)) slid natural objects against enamel, concluding anything less hard than enamel would rub, not abrade, its surface (producing no immediate wear). This category includes all organic plant matter. Particles harder than enamel, with sufficiently angular surfaces, could abrade it immediately, prerequisites that silica/silicate particles alone possess. Xia
et al.
(Xia, Zheng, Huang, Tian, Chen, Zhou, Ungar, Qian. 2015
Proc. Natl Acad. Sci. USA
112
, 10 669–10 672. (
doi:10.1073/pnas.1509491112
)) countered with experiments using brass and aluminium balls. Their bulk hardness was lower than enamel, but the latter was abraded. We examined the ball exteriors to address this discrepancy. The aluminium was surfaced by a thin rough oxide layer harder than enamel. Brass surfaces were smoother, but work hardening during manufacture gave them comparable or higher hardness than enamel. We conclude that Xia
et al
.'s results are actually predicted by the mechanical model of Lucas
et al
. To explain wear patterns, we present a new model of textural formation, based on particle properties and presence/absence of silica(tes).
The polyphyly of
Plasmodium
: comprehensive phylogenetic analyses of the malaria parasites (order Haemosporida) reveal widespread taxonomic conflict
Authors: Galen Spencer C. , Borner Janus , Martinsen Ellen S. , Schaer Juliane , Austin Christopher C. , West Christopher J. , Perkins Susan L.
Published: May 2018

The evolutionary relationships among the apicomplexan blood pathogens known as the malaria parasites (order Haemosporida), some of which infect nearly 200 million humans each year, has remained a vexing phylogenetic problem due to limitations in taxon sampling, character sampling and the extreme nucleotide base composition biases that are characteristic of this clade. Previous phylogenetic work on the malaria parasites has often lacked sufficient representation of the broad taxonomic diversity within the Haemosporida or the multi-locus sequence data needed to resolve deep evolutionary relationships, rendering our understanding of haemosporidian life-history evolution and the origin of the human malaria parasites incomplete. Here we present the most comprehensive phylogenetic analysis of the malaria parasites conducted to date, using samples from a broad diversity of vertebrate hosts that includes numerous enigmatic and poorly known haemosporidian lineages in addition to genome-wide multi-locus sequence data. We find that if base composition differences were corrected for during phylogenetic analysis, we recovered a well-supported topology indicating that the evolutionary history of the malaria parasites was characterized by a complex series of transitions in life-history strategies and host usage. Notably we find that
Plasmodium
, the malaria parasite genus that includes the species of human medical concern, is polyphyletic with the life-history traits characteristic of this genus having evolved in a dynamic manner across the phylogeny. We find support for multiple instances of gain and loss of asexual proliferation in host blood cells and production of haemozoin pigment, two traits that have been used for taxonomic classification as well as considered to be important factors for parasite virulence and used as drug targets. Lastly, our analysis illustrates the need for a widespread reassessment of malaria parasite taxonomy.
Biodegradability standards for carrier bags and plastic films in aquatic environments: a critical review
Authors: Harrison Jesse P. , Boardman Carl , O'Callaghan Kenneth , Delort Anne-Marie , Song Jim
Published: May 2018

Plastic litter is encountered in aquatic ecosystems across the globe, including polar environments and the deep sea. To mitigate the adverse societal and ecological impacts of this waste, there has been debate on whether ‘biodegradable' materials should be granted exemptions from plastic bag bans and levies. However, great care must be exercised when attempting to define this term, due to the broad and complex range of physical and chemical conditions encountered within natural ecosystems. Here, we review existing international industry standards and regional test methods for evaluating the biodegradability of plastics within aquatic environments (wastewater, unmanaged freshwater and marine habitats). We argue that current standards and test methods are insufficient in their ability to realistically predict the biodegradability of carrier bags in these environments, due to several shortcomings in experimental procedures and a paucity of information in the scientific literature. Moreover, existing biodegradability standards and test methods for aquatic environments do not involve toxicity testing or account for the potentially adverse ecological impacts of carrier bags, plastic additives, polymer degradation products or small (microscopic) plastic particles that can arise via fragmentation. Successfully addressing these knowledge gaps is a key requirement for developing new biodegradability standard(s) for lightweight carrier bags.
Molecular phylogeny of
Culex
subgenus
Melanoconion
(Diptera: Culicidae) based on nuclear and mitochondrial protein-coding genes
Authors: Torres-Gutierrez Carolina , de Oliveira Tatiane M. P. , Emerson Kevin J. , Sterlino Bergo Eduardo , Mureb Sallum Maria Anice
Published: May 2018

The subgenus
Melanoconion
of the mosquito genus
Culex
is taxonomically diverse and is widely distributed in the Neotropical Region, with 10 species occurring in the Nearctic Region. Species of this subgenus pose a taxonomical challenge because morphological identification is based largely on anatomical characters of the male genitalia. We addressed the monophyly of the Spissipes and Melanoconion Sections of the subgenus
Melanoconion
and some of the informal groups in each section. Our sample taxa included 97 specimens representing 43 species, from which we analysed fragments of two single-copy nuclear genes (
CAD
,
HB
) and one mitochondrial gene (
COI
). Phylogenetic relationships within the subgenus are presented based on results of maximum-likelihood and Bayesian analyses using a multi-locus matrix of DNA sequences. We show a molecular phylogeny of
Melanoconion
in which both sections were recovered as monophyletic groups. The monophyly of the Atratus and Pilosus groups was confirmed. Within each section, other monophyletic groups were recovered highlighting the potential need for future nomenclature rearrangement. The phylogenetic signal contained in nuclear genes, when analysed together, was more informative than each gene analysed separately, corroborating monophyly of
Melanoconion
relative to
Culex
(
Culex
) species included in the analyses, the Melanoconion and Spissipes Sections and some species groups. Our results provide new information for the classification of the subgenus and additional data that can be used to improve species identification when a more representative taxon sampling is available.
A Ni-based catalyst with polyvinyl pyrrolidone as a dispersant supported in a pretreated fluid catalytic cracking catalyst residue for C9 petroleum resin (C9 PR) hydrogenation
Authors: Chen Dong , Wang Linlin , Chen Xiaopeng , Wei Xiaojie , Liang Jiezhen , Jiang Jiao , Liang Baofang
Published: May 2018

A Ni-based catalyst (Ni-PVP/PFC3R) with polyvinyl pyrrolidone (PVP) as a dispersant supported in a pretreated fluid catalytic cracking catalyst residue (PFC3R) was synthesized and applied to C9 petroleum resin (C9 PR) hydrogenation. For comparison, a Ni catalyst without PVP (Ni/PFC3R) was prepared in the same way. Ni-PVP/PFC3R exhibited higher activity and better stability. The catalysts were characterized by X-ray diffraction, scanning electron microscope, H2-temperature programmed reduction/temperature programmed desorption, Fourier transform infrared spectroscopy and the Brunauer–Emmett–Teller method. The catalysts had a smaller crystallite size and stronger interactions between the Ni species and the PFC3R support in the presence of PVP. The effects of nickel loading, H2pressure, temperature and reaction time for C9 PR hydrogenation over Ni-PVP/PFC3R were investigated. The bromine number was reduced to 1.25 under the following conditions: nickel content of 12 wt%, PVP amount of 1.5 wt%, temperature of 270°C, H2pressure of 8 MPa and reaction time of 240 min.
Determination of sulfonamides in milk by capillary electrophoresis with PEG@MoS
2
as a dispersive solid-phase extraction sorbent
Authors: An Jianxin , Wang Xuan , Ming Meiting , Li Jian , Ye Nengsheng
Published: May 2018

A synthetic polyethylene glycol-molybdenum disulfide (PEG@MoS
2
) composite was prepared using a simple method, and the application of this material in dispersive solid-phase extraction (DSPE) was investigated for the enrichment of eight sulfonamides (SAs) in milk samples. The composite was characterized by energy dispersive spectroscopy, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and Brunauer–Emmett–Teller measurements. The results showed that the MoS
2
synthesized in the presence of PEG has the advantage of a larger surface area and that the adsorption effect of this MoS
2
was enhanced. After extraction, the eight SAs were separated by capillary zone electrophoresis with a good linear relationship (
R
2
 > 0.9902) in the range of 0.3–30 µg ml
−1
and good precision (between 0.32% and 9.83%). Additionally, good recoveries (between 60.52% and 110.91%) were obtained for the SAs in the milk samples. The developed PEG@MoS
2
-based DSPE method could be applied for the enrichment of SAs in real milk samples.
Totally synthetic microperoxidase-11
Authors: Tanabe Junichi , Nakano Koji , Hirata Ryutaro , Himeno Toshiki , Ishimatsu Ryoichi , Imato Toshihiko , Okabe Hirotaka , Matsuda Naoki
Published: May 2018

A totally synthetic microperoxidase-11 (MP-11) is reported. Accordingly, the undecapeptide (VQKCAQCHTVE) was synthesized by solid-phase peptide synthesis followed by the thiol-ene click reaction with haemin for reconstitution. High-speed atomic force microscopy measurement conducted in water confirmed the protein reconstitution by visualizing the morphological differences as animated molecular images. The synthetic MP-11 showed a considerable magnitude of catalytic activity (27%) against the natural MP-11 in the oxidation of 3,3′,5,5′-tetramethylbenzidine by hydrogen peroxide, whereas it showed very low (2.7%) activity of a synthetic variant with a point mutation (VQKCAQC

M

TVE, H8M). Slab waveguide spectroscopic measurements revealed that the ferrous/ferric redox reaction occurred by the direct electron transfer with specific spectral changes. Indeed, if hydrogen peroxide existed in the solution phase, the peroxidase-modified electrode showed catalytic current–voltage behaviour regardless of whether it was prepared using natural MP-11 or the synthetic MP-11. If a substrate recycling reaction was assumed, computer simulation well reproduced the experimental curves to give a global set of electrocatalytic reaction parameters. In any of the experiments, the synthetic MP-11 and natural MP-11 gave almost identical results. Our approach will be a convenient means of preparing MP-11, as well as its mutants, that does not rely on nature.
Rural plastic emissions into the largest mountain lake of the Eastern Carpathians
Authors: Mihai Florin-Constantin
Published: May 2018

The lack of proper waste collection systems leads to plastic pollution in rivers in proximity to rural communities. This environmental threat is more widespread among mountain communities which are prone to frequent flash floods during the warm season. This paper estimates the amounts of plastic bottles dumped into the Izvoru Muntelui lake by upstream rural communities. The plastic pollution dimension between seasonal floods which affected the Bistrita catchment area during 2005–2012 is examined. The floods dumped over 290 tonnes of plastic bottles into the lake. Various scenarios are tested in order to explain each amount of plastic waste collected by local authorities during sanitation activities. The results show that rural municipalities are responsible for 85.51% of total plastic bottles collected during 2005–2010. The source of plastic pollution is mainly local. The major floods of July 2008 and June 2010 collected most of the plastic bottles scattered across the Bistrita river catchment (56 villages) and dumped them into the lake. These comparisons validate the proposed method as a reliable tool in the assessment process of river plastic pollution, which may also be applied in other geographical areas. Tourism and leisure activities are also found to be responsible for plastic pollution in the study area. A new regional integrated waste management system should improve the waste collection services across rural municipalities at the county level when it is fully operational. This paper demonstrates that rural communities are significant contributors of plastics into water bodies.
Synergistic effect of acidity and extraframework position in faujasite on renewable
p
-xylene production
Authors: Mahmoud Eyas
Published: May 2018

p
-Xylene is a commodity chemical used for the manufacture of plastic bottles and textiles. For the biomass-based route from 2,5-dimethylfuran (DMF) and ethylene, the properties of the catalyst such as acidity effect, product selectivity and catalyst activity play an important role. To determine the effect of acidity and extraframework position in faujasite zeolite on
p
-xylene selectivity, type Y (Si/Al = 40 and Si/Al = 2.55) and X (Si/Al = 1.25) zeolites containing the extraframework Lewis acids Na+, K+, Li+, Ag+ and Cu+, and a Brønsted acid-containing zeolite, HY (Si/Al = 40), were prepared and tested for
p
-xylene production under solvent-free conditions and at low conversions (less than 35%). Here it is reported that NaX zeolite catalyses DMF and ethylene conversion to
p
-xylene with 91% selectivity at 30% conversion, which is better than the 25%
p
-xylene selectivity obtained when using HY at similar conversion. ANOVA was used to show that there is a synergistic effect between acidity and extraframework position on the rate of
p
-xylene production. At 7% DMF conversion, Lewis acids were more selective than the Brønsted acid tested (50 versus 30%
p
-xylene selectivity).
p
-Xylene selectivity is optimal when using Lewis acids with moderate acidity and extraframework positions located in the faujasite supercage (sites II and III).
Improving rolling bearing online fault diagnostic performance based on multi-dimensional characteristics
Authors: Yang Chuanlei , Wang Hechun , Gao Zhanbin , Cui Xinjie
Published: May 2018

As the main cause of failure and damage to rotating machinery, rolling bearing failure can result in huge economic losses. As the rolling bearing vibration signal is nonlinear and has non-stationary characteristics, the health status information distributed in the rolling bearing vibration signal is complex. Using common time-domain or frequency-domain approaches cannot easily enable an accurate assessment of rolling bearing health. In this paper, a novel rolling bearing fault diagnostic method based on multi-dimensional characteristics was developed to meet the requirements for accurate diagnosis of different fault types and severities with real-time computational performance. First, a multi-dimensional feature extraction algorithm based on entropy characteristics, Holder coefficient characteristics and improved generalized fractal box-counting dimension characteristics was performed to extract the health status feature vectors from the bearing vibration signals. Second, a grey relation algorithm was employed to achieve bearing fault pattern recognition intelligently using the extracted multi-dimensional feature vector. This experimental study has illustrated that the proposed method can effectively recognize different fault types and severities after integration of the improved fractal box-counting dimension into the multi-dimensional characteristics, in comparison with existing pattern recognition methods.
Universals and cultural diversity in the expression of gratitude
Authors: Floyd Simeon , Rossi Giovanni , Baranova Julija , Blythe Joe , Dingemanse Mark , Kendrick Kobin H. , Zinken Jörg , Enfield N. J.
Published: May 2018

Gratitude is argued to have evolved to motivate and maintain social reciprocity among people, and to be linked to a wide range of positive effects—social, psychological and even physical. But is socially reciprocal behaviour dependent on the expression of gratitude, for example by saying ‘thank you’ as in English? Current research has not included cross-cultural elements, and has tended to conflate gratitude as an emotion with gratitude as a linguistic practice, as might appear to be the case in English. Here, we ask to what extent people express gratitude in different societies by focusing on episodes of everyday life where someone seeks and obtains a good, service or support from another, comparing these episodes across eight languages from five continents. We find that expressions of gratitude in these episodes are remarkably rare, suggesting that social reciprocity in everyday life relies on tacit understandings of rights and duties surrounding mutual assistance and collaboration. At the same time, we also find minor cross-cultural variation, with slightly higher rates in Western European languages English and Italian, showing that universal tendencies of social reciprocity should not be equated with more culturally variable practices of expressing gratitude. Our study complements previous experimental and culture-specific research on gratitude with a systematic comparison of audiovisual corpora of naturally occurring social interaction from different cultures from around the world.
A worldwide model for boundaries of urban settlements
Authors: Oliveira Erneson A. , Furtado Vasco , Andrade José S. , Makse Hernán A.
Published: May 2018

The shape of urban settlements plays a fundamental role in their sustainable planning. Properly defining the boundaries of cities is challenging and remains an open problem in the science of cities. Here, we propose a worldwide model to define urban settlements beyond their administrative boundaries through a bottom-up approach that takes into account geographical biases intrinsically associated with most societies around the world, and reflected in their different regional growing dynamics. The generality of the model allows one to study the scaling laws of cities at all geographical levels: countries, continents and the entire world. Our definition of cities is robust and holds to one of the most famous results in social sciences: Zipf’s law. According to our results, the largest cities in the world are not in line with what was recently reported by the United Nations. For example, we find that the largest city in the world is an agglomeration of several small settlements close to each other, connecting three large settlements: Alexandria, Cairo and Luxor. Our definition of cities opens the doors to the study of the economy of cities in a systematic way independently of arbitrary definitions that employ administrative boundaries.
Revealing new dynamical patterns in a reaction–diffusion model with cyclic competition via a novel computational framework
Authors: Cangiani A. , Georgoulis E. H. , Morozov A. Yu. , Sutton O. J.
Published: May 2018

Understanding how patterns and travelling waves form in chemical and biological reaction–diffusion models is an area which has been widely researched, yet is still experiencing fast development. Surprisingly enough, we still do not have a clear understanding about all possible types of dynamical regimes in classical reaction–diffusion models, such as Lotka–Volterra competition models with spatial dependence. In this study, we demonstrate some new types of wave propagation and pattern formation in a classical three species cyclic competition model with spatial diffusion, which have been so far missed in the literature. These new patterns are characterized by a high regularity in space, but are different from patterns previously known to exist in reaction–diffusion models, and may have important applications in improving our understanding of biological pattern formation and invasion theory. Finding these new patterns is made technically possible by using an automatic adaptive finite element method driven by a novela posteriorierror estimate which is proved to provide a reliable bound for the error of the numerical method. We demonstrate how this numerical framework allows us to easily explore the dynamical patterns in both two and three spatial dimensions.
Quantum stopwatch: how to store time in a quantum memory
Authors: Yang Yuxiang , Chiribella Giulio , Hayashi Masahito
Published: May 2018

Quantum mechanics imposes a fundamental trade-off between the accuracy of time measurements and the size of the systems used as clocks. When the measurements of different time intervals are combined, the errors due to the finite clock size accumulate, resulting in an overall inaccuracy that grows with the complexity of the set-up. Here, we introduce a method that, in principle, eludes the accumulation of errors by coherently transferring information from a quantum clock to a quantum memory of the smallest possible size. Our method could be used to measure the total duration of a sequence of events with enhanced accuracy, and to reduce the amount of quantum communication needed to stabilize clocks in a quantum network.
Data-driven forecasting of high-dimensional chaotic systems with long short-term memory networks
Authors: Vlachas Pantelis R. , Byeon Wonmin , Wan Zhong Y. , Sapsis Themistoklis P. , Koumoutsakos Petros
Published: May 2018

We introduce a data-driven forecasting method for high-dimensional chaotic systems using long short-term memory (LSTM) recurrent neural networks. The proposed LSTM neural networks perform inference of high-dimensional dynamical systems in their reduced order space and are shown to be an effective set of nonlinear approximators of their attractor. We demonstrate the forecasting performance of the LSTM and compare it with Gaussian processes (GPs) in time series obtained from the Lorenz 96 system, the Kuramoto–Sivashinsky equation and a prototype climate model. The LSTM networks outperform the GPs in short-term forecasting accuracy in all applications considered. A hybrid architecture, extending the LSTM with a mean stochastic model (MSM–LSTM), is proposed to ensure convergence to the invariant measure. This novel hybrid method is fully data-driven and extends the forecasting capabilities of LSTM networks.
Collective ritual and social support networks in rural South India
Authors: Power Eleanor A.
Published: May 2018

The scholarship on religion has long argued that collective worship helps foster social cohesion. Despite the pervasiveness of this contention, rigorous quantitative evaluations of it have been surprisingly limited. Here, I draw on network data representing the ties of social support among Hindu residents of a South Indian village to evaluate the association between collective religious ritual and social cohesion. I find that those who partake in collective religious rituals together have a higher probability of having a supportive relationship than those who do not. At the structural level, this corresponds to denser connections among co-participants. At the individual level, participants are more embedded in the local community of co-religionists, but are not disassociating themselves from members of other religious denominations. These patterns hold most strongly for co-participation in the recurrent, low-arousal monthly worships at the temple, and are suggestive for co-participation in the intense and dysphoric ritual acts carried out as part of an annual festival. Together, these findings provide clear empirical evidence of the lasting relationship between collective religious ritual and social cohesion.
Mechanisms and seasonal drivers of calcification in the temperate coralTurbinaria reniformisat its latitudinal limits
Authors: Ross Claire L. , Schoepf Verena , DeCarlo Thomas M. , McCulloch Malcolm T.
Published: May 2018

High-latitude coral reefs provide natural laboratories for investigating the mechanisms and limits of coral calcification. While the calcification processes of tropical corals have been studied intensively, little is known about how their temperate counterparts grow under much lower temperature and light conditions. Here, we report the results of a long-term (2-year) study of seasonal changes in calcification rates, photo-physiology and calcifying fluid (cf) chemistry (using boron isotope systematics and Raman spectroscopy) for the coralTurbinaria reniformisgrowing near its latitudinal limits (34.5° S) along the southern coast of Western Australia. In contrast with tropical corals, calcification rates were found to be threefold higher during winter (16 to 17° C) compared with summer (approx. 21° C), and negatively correlated with light, but lacking any correlation with temperature. These unexpected findings are attributed to a combination of higher chlorophyll a, and hence increased heterotrophy during winter compared with summer, together with the corals' ability to seasonally modulate pHcf, with carbonate ion concentrationbeing the main controller of calcification rates. Conversely, calcium ion concentration [Ca2+]cfdeclined with increasing calcification rates, resulting in aragonite saturation statesΩcfthat were stable yet elevated fourfold above seawater values. Our results show that corals growing near their latitudinal limits exert strong physiological control over their cf in order to maintain year-round calcification rates that are insensitive to the unfavourable temperature regimes typical of high-latitude reefs.
Migration promotes plasmid stability under spatially heterogeneous positive selection
Authors: Harrison Ellie , Hall James P. J. , Brockhurst Michael A.
Published: May 2018

Bacteria–plasmid associations can be mutualistic or antagonistic depending on the strength of positive selection for plasmid-encoded genes, with contrasting outcomes for plasmid stability. In mutualistic environments, plasmids are swept to high frequency by positive selection, increasing the likelihood of compensatory evolution to ameliorate the plasmid cost, which promotes long-term stability. In antagonistic environments, plasmids are purged by negative selection, reducing the probability of compensatory evolution and driving their extinction. Here we show, using experimental evolution ofPseudomonas fluorescensand the mercury-resistance plasmid, pQBR103, that migration promotes plasmid stability in spatially heterogeneous selection environments. Specifically, migration from mutualistic environments, by increasing both the frequency of the plasmid and the supply of compensatory mutations, stabilized plasmids in antagonistic environments where, without migration, they approached extinction. These data suggest that spatially heterogeneous positive selection, which is common in natural environments, coupled with migration helps to explain the stability of plasmids and the ecologically important genes that they encode.
Morph-specific artificial selection reveals a constraint on the evolution of polyphenisms
Authors: Buzatto Bruno A. , Clark Huon L. , Tomkins Joseph L.
Published: May 2018

Theory predicts that the evolution of polyphenic variation is facilitated where morphs are genetically uncoupled and free to evolve towards their phenotypic optima. However, the assumption that developmentally plastic morphs can evolve independently has not been tested directly. Using morph-specific artificial selection, we investigated correlated evolution between the sexes and male morphs of the bulb mite
Rhizoglyphus echinopus
. Large ‘fighter’ males have a thick and sharply terminating pair of legs used to kill rival males, while small ‘scrambler’ males have unmodified legs, and search for unguarded females, avoiding fights. We selected on the relative leg width of only the fighter male morph, tracked the evolutionary responses in fighters and the correlated evolutionary responses in scramblers and females that were untouched by direct selection. Fighters diverged in relative leg thickness after six generations; assaying scramblers and females at the ninth generation we observed correlated responses in relative leg width in both. Our results represent strong evidence for the evolution of intraspecific phenotypic diversity despite correlated evolution between morphs and sexes, challenging the idea that male morphs are genetically uncoupled and free to independently respond to selection. We therefore question the perceived necessity for genetic independence in traits with extreme phenotypic plasticity.
Peripherally injected ghrelin and leptin reduce food hoarding and mass gain in the coal tit (
Periparus ater
)
Authors: Henderson Lindsay J. , Cockcroft Rowan C. , Kaiya Hiroyuki , Boswell Timothy , Smulders Tom V.
Published: May 2018

In birds little is known about the hormonal signals that communicate nutritional state to the brain and regulate appetitive behaviours. In mammals, the peptide hormones ghrelin and leptin elevate and inhibit consumption and food hoarding, respectively. But in birds, administration of both ghrelin and leptin inhibit food consumption. The role of these hormones in the regulation of food hoarding in avian species has not been examined. To investigate this, we injected wild caught coal tits (
Periparus ater
) with leptin, high-dose ghrelin, low-dose ghrelin and a saline control in the laboratory. We then measured food hoarding and mass gain, as a proxy of food consumption, every 20 min for 2 h post-injection. Both high-dose ghrelin and leptin injections significantly reduced hoarding and mass gain compared with controls. Our results provide the first evidence that hoarding behaviour can be reduced by both leptin and ghrelin in a wild bird. These findings add to evidence that the hormonal control of food consumption and hoarding in avian species differs from that in mammals. Food hoarding and consumptive behaviours consistently show the same response to peripheral signals of nutritional state, suggesting that the hormonal regulation of food hoarding has evolved from the consumption regulatory system.
Behavioural homogenization with spillovers in a normative domain
Authors: Efferson Charles , Vogt Sonja
Published: May 2018

The importance of culture for human social evolution hinges largely on the extent to which culture supports outcomes that would not otherwise occur. An especially controversial claim is that social learning leads groups to coalesce around group-typical behaviours and associated social norms that spill over to shape choices in asocial settings. To test this, we conducted an experiment with 878 groups of participants in 116 communities in Sudan. Participants watched a short film and evaluated the appropriate way to behave in the situation dramatized in the film. Each session consisted of an asocial condition in which participants provided private evaluations and a social condition in which they provided public evaluations. Public evaluations allowed for social learning. Across sessions, we randomized the order of the two conditions. Public choices dramatically increased the homogeneity of normative evaluations. When the social condition was first, this homogenizing effect spilled over to subsequent asocial conditions. The asocial condition when first was thus alone in producing distinctly heterogeneous groups. Altogether, information about the choices of others led participants to converge rapidly on similar normative evaluations that continued to hold sway in subsequent asocial settings. These spillovers were at least partly owing to the combined effects of conformity and self-consistency. Conformity dominated self-consistency when the two mechanisms were in conflict, but self-consistency otherwise produced choices that persisted through time. Additionally, the tendency to conform was heterogeneous. Females conformed more than males, and conformity increased with the number of other people a decision-maker observed before making her own choice.
Magnetocarcinogenesis: is there a mechanism for carcinogenic effects of weak magnetic fields?
Authors: Juutilainen Jukka , Herrala Mikko , Luukkonen Jukka , Naarala Jonne , Hore P. J.
Published: May 2018

Extremely low-frequency (ELF) magnetic fields have been classified as possibly carcinogenic, mainly based on rather consistent epidemiological findings suggesting a link between childhood leukaemia and 50–60 Hz magnetic fields from power lines. However, causality is not the only possible explanation for the epidemiological associations, as animal andin vitroexperiments have provided only limited support for carcinogenic effects of ELF magnetic fields. Importantly, there is no generally accepted biophysical mechanism that could explain such effects. In this review, we discuss the possibility that carcinogenic effects are based on the radical pair mechanism (RPM), which seems to be involved in magnetoreception in birds and certain other animals, allowing navigation in the geomagnetic field. We review the current understanding of the RPM in magnetoreception, and discuss cryptochromes as the putative magnetosensitive molecules and their possible links to cancer-relevant biological processes. We then propose a hypothesis for explaining the link between ELF fields and childhood leukaemia, discuss the strengths and weaknesses of the current evidence, and make proposals for further research.
Phytoplankton size diversity and ecosystem function relationships across oceanic regions
Authors: Acevedo-Trejos Esteban , Marañón Emilio , Merico Agostino
Published: May 2018

Trait diversity, a key component of biodiversity, mediates many essential ecosystem functions and services. However, the mechanisms behind such relationships at large spatial scales are not fully understood. Here we adopt the functional biogeography approach to investigate how the size composition of phytoplankton communities relates to primary production and export production along a broad latitudinal gradient. Using
in situ
phytoplankton size distribution data and a trait-based model, we find an increase in the average phytoplankton size, size diversity, primary production and export when moving from low to high latitudes. Our analysis indicates that the interplay between spatio-temporal heterogeneities in environmental conditions and a trade-off between the high affinity for nutrients of smaller cells and the ability to avoid predation by larger cells are the main mechanisms driving the observed patterns. Our results also suggest that variations in size diversity alone do not directly lead to changes in primary production and export. The trade-off thus introduces a feedback that influences the relationship between size diversity and ecosystem functions. These findings support the importance of environmentally mediated trade-offs as crucial mechanisms shaping biodiversity and ecosystem function relationships at large spatial scales.
Density-dependent interspecific interactions and the complexity–stability relationship
Authors: Kawatsu Kazutaka , Kondoh Michio
Published: May 2018

Ever since May theorized that communities with larger numbers of species or interspecific interactions are inherently unstable, the mechanism allowing for the stable existence of complex communities in nature has been a central question in ecology. The main efforts to answer this question have sought to identify non-random features of ecological systems that can reverse a negative complexity–stability relationship into a positive one, but are far from successful, especially in their generality. Here, using the traditional community matrix analysis, we show that variation in the density dependence of interspecific interactions, which should be ubiquitous in nature, can dramatically affect the complexity–stability relationship. More specifically, we reveal that a positive complexity–stability relationship arises when harmful interspecific effects have larger density dependence than beneficial ones, regardless of the signs (i.e. positive or negative) of their dependence. Furthermore, numerical simulations demonstrated the synergistic stabilizing effect of interaction type diversity and density-dependence variation. Thus, this concept of density-dependence variation advances our understanding of the complexity–stability relationship in the real world.
Subset-Based Analysis using Gene-Environment Interactions for Discovery of Genetic Associations across Multiple Studies or Phenotypes
Authors: Yu Youfei , Xia Lu , Lee Seunggeun , Zhou Xiang , Stringham Heather M , Boehnke Michael , Mukherjee Bhramar
Published: May 2018

Objectives

Classical methods for combining summary data from genome-wide association studies (GWAS) only use marginal genetic effects and power can be compromised in the presence of heterogeneity. We aim to enhance the discovery of novel associated loci in the presence of heterogeneity of genetic effects in sub-groups defined by an environmental factor.

Methods

We present a p-value Assisted Subset Testing for Associations (pASTA) framework that generalizes the previously proposedassociation analysis based on subsets (ASSET) method by incorporating gene-environment (G-E) interactions into the testing procedure. We conduct simulation studies and provide two data examples.

Results

Simulation studies show that our proposal is more powerful than methods based on marginal associations in the presence of G-E interactions and maintains comparable power even in their absence. Both data examples demonstrate that our method can increase power to detect overall genetic associations and identify novel studies/phenotypes that contribute to the association.

Conclusions

Our proposed method can be a useful screening tool to identify candidate single nucleotide polymorphisms (SNPs) that are potentially associated with the trait(s) of interest for further validation. It also allows researchers to determine the most probable subset of traits that exhibit genetic associations in addition to the enhancement of power.