Alternating proximal penalization algorithm for the modified multiple-sets split feasibility problems

In this paper, we present an extended alternating proximal penalization algorithm for the modified multiple-sets feasibility problem. For this method, we first show that the sequences generated by the algorithm are summable, which guarantees that the distance between two adjacent iterates converges to zero, and then we establish the global convergence of the algorithm provided that the penalty parameter tends to zero.

Mandibulate convergence in an armoured Cambrian stem chelicerate

BACKGROUND

Chelicerata represents a vast clade of mostly predatory arthropods united by a distinctive body plan throughout the Phanerozoic. Their origins, however, with respect to both their ancestral morphological features and their related ecologies, are still poorly understood. In particular, it remains unclear whether their major diagnostic characters were acquired early on, and their anatomical organization rapidly constrained, or if they emerged from a stem lineage encompassing an array of structural variations, based on a more labile "panchelicerate" body plan.

RESULTS

In this study, we reinvestigated the problematic middle Cambrian arthropod Habelia optata Walcott from the Burgess Shale, and found that it was a close relative of Sanctacaris uncata Briggs and Collins (in Habeliida, ord. nov.), both retrieved in our Bayesian phylogeny as stem chelicerates. Habelia possesses an exoskeleton covered in numerous spines and a bipartite telson as long as the rest of the body. Segments are arranged into three tagmata. The prosoma includes a reduced appendage possibly precursor to the chelicera, raptorial endopods connected to five pairs of outstandingly large and overlapping gnathobasic basipods, antennule-like exopods seemingly dissociated from the main limb axis, and, posteriorly, a pair of appendages morphologically similar to thoracic ones. While the head configuration of habeliidans anchors a seven-segmented prosoma as the chelicerate ground pattern, the peculiar size and arrangement of gnathobases and the presence of sensory/tactile appendages also point to an early convergence with the masticatory head of mandibulates.

CONCLUSIONS

Although habeliidans illustrate the early appearance of some diagnostic chelicerate features in the evolution of euarthropods, the unique convergence of their cephalons with mandibulate anatomies suggests that these traits retained an unusual variability in these taxa. The common involvement of strong gnathal appendages across non-megacheirans Cambrian taxa also illustrates that the specialization of the head as the dedicated food-processing tagma was critical to the emergence of both lineages of extant euarthropods-Chelicerata and Mandibulata-and implies that this diversification was facilitated by the expansion of durophagous niches.

From ground pools to treeholes: convergent evolution of habitat and phenotype in Aedes mosquitoes

BACKGROUND

Invasive mosquito species are responsible for millions of vector-borne disease cases annually. The global invasive success of Aedes mosquitoes such as Aedes aegypti and Aedes albopictus has relied on the human transport of immature stages in container habitats. However, despite the importance of these mosquitoes and this ecological specialization to their widespread dispersal, evolution of habitat specialization in this group has remained largely unstudied. We use comparative methods to evaluate the evolution of habitat specialization and its potential influence on larval morphology, and evaluate whether container dwelling and invasiveness are monophyletic in Aedes.

RESULTS

We show that habitat specialization has evolved repeatedly from ancestral ground pool usage to specialization in container habitats. Furthermore, we find that larval morphological scores are significantly associated with larval habitat when accounting for evolutionary relationships. We find that Ornstein-Uhleinbeck models with unique optima for each larval habitat type are preferred over several other models based predominantly on neutral processes, and that OU models can reliably simulate real morphological data.

CONCLUSIONS

Our results demonstrate that multiple lineages of Aedes have convergently evolved a key trait associated with invasive success: the use of container habitats for immature stages. Moreover, our results demonstrate convergence in morphological characteristics as well, and suggest a role of adaptation to habitat specialization in driving phenotypic diversity in this mosquito lineage. Finally, our results highlight that the genus Aedes is not monophyletic.

Health Convergence Between East and West Germany as Reflected in Long-Term Cause-Specific Mortality Trends: To What Extent was it Due to Reunification?

The sizeable mortality gap between the German Democratic Republic (East Germany) and the pre-unified Federal Republic of Germany (West Germany) narrowed rapidly after the two states were unified. Despite extensive research, the mechanisms underlying the convergence process are still not fully understood. Significant changes to coding practices and the system of data collection introduced in East Germany shortly after reunification have further complicated the ability of researchers to interpret mortality trends. Our aim is to assess the role of German reunification in the convergence process in light of the evolution of long-term mortality trends by causes of death. Compared to previous studies, we rely on much more detailed mortality data, which we first adjust for notable distortions. We propose an upward correction of cancer mortality, as well as corrections that account for obvious changes in the items selected within the ICD chapter of circulatory diseases. We identify three distinct processes that took place in East Germany around the time of reunification: (1) a sustained reduction in mortality that started before reunification; (2) a temporary increase in mortality in 1990-1991 that was related to the abrupt social transition, as reflected by socially sensitive causes such as accidents, alcohol-related diseases, and acute myocardial infarction; and (3) a reunification-driven process of convergence that was mostly caused by the accelerated decline in mortality from cerebrovascular and chronic heart diseases. Mortality improvements observed in the GDR starting in the 1980s might be interpreted as the first signs of a cardiovascular revolution. Shifts in individual behaviour likely started before reunification, whereas the real progress in medical care occurred later with the implementation of the Western system of health care. We therefore conclude that German reunification per se did not initiate the convergence process, but rather reinforced and accelerated trends that were already apparent.

A convergence algorithm for correlation of breech face images based on the congruent matching cells (CMC) method

The Congruent Matching Cells (CMC) method was invented at the National Institute of Standards and Technology (NIST) for accurate firearm evidence identification and error rate estimation. The CMC method is based on the principle of discretization. The toolmark image of the reference sample is divided into correlation cells. Each cell is registered to the cell-sized area of the compared image that has maximum surface topography similarity. For each resulting cell pair, one parameter quantifies the similarity of the cell surface topography and three parameters quantify the pattern congruency of the registration position and orientation. An identification (declared match) requires a significant number of CMCs, that is, cell pairs that meet both similarity and pattern congruency requirements. The use of cell correlations reduces the effects of "invalid regions" in the compared image pairs and increases the correlation accuracy. The identification accuracy of the CMC method can be further improved by considering a feature named "convergence," that is, the tendency of the x-y registration positions of the correlated cell pairs to converge at the correct registration angle when comparing same-source samples at different relative orientations. In this paper, the difference of the convergence feature between known matching (KM) and known non-matching (KNM) image pairs is characterized, based on which an improved algorithm is developed for breech face image correlations using the CMC method. Its advantage is demonstrated by comparison with three existing CMC algorithms using four datasets. The datasets address three different brands of consecutively manufactured pistol slides, with significant differences in the distribution overlap of cell pair topography similarity for KM and KNM image pairs. For the same CMC threshold values, the convergence algorithm demonstrates noticeably improved results by reducing the number of false-positive or false-negative CMCs in a comparison.

Many-to-one form-to-function mapping weakens parallel morphological evolution

Evolutionary ecologists aim to explain and predict evolutionary change under different selective regimes. Theory suggests that such evolutionary prediction should be more difficult for biomechanical systems in which different trait combinations generate the same functional output: "many-to-one mapping." Many-to-one mapping of phenotype to function enables multiple morphological solutions to meet the same adaptive challenges. Therefore, many-to-one mapping should undermine parallel morphological evolution, and hence evolutionary predictability, even when selection pressures are shared among populations. Studying 16 replicate pairs of lake- and stream-adapted threespine stickleback (Gasterosteus aculeatus), we quantified three parts of the teleost feeding apparatus and used biomechanical models to calculate their expected functional outputs. The three feeding structures differed in their form-to-function relationship from one-to-one (lower jaw lever ratio) to increasingly many-to-one (buccal suction index, opercular 4-bar linkage). We tested for (1) weaker linear correlations between phenotype and calculated function, and (2) less parallel evolution across lake-stream pairs, in the many-to-one systems relative to the one-to-one system. We confirm both predictions, thus supporting the theoretical expectation that increasing many-to-one mapping undermines parallel evolution. Therefore, sole consideration of morphological variation within and among populations might not serve as a proxy for functional variation when multiple adaptive trait combinations exist.

The Biophysical Effects of Neolithic Island Colonization: General Dynamics and Sociocultural Implications

Does anthropogenic environmental change constrain long-term sociopolitical outcomes? It is clear that human colonization of islands radically alters their biological and physical systems. Despite considerable contextual variability in local specificities of this alteration, I argue that these processes are to some extent regular, predictable, and have socio-political implications. Reviewing the data for post-colonization ecodynamics, I show that Neolithic colonization of previously insulated habitats drives biotic homogenization. I argue that we should expect such homogenization to promote regular types of change in biophysical systems, types of change that can be described in sum as environmentally convergent. Such convergence should have significant implications for human social organization over the long term, and general dynamics of this sort are relevant in the context of understanding remarkably similar social evolutionary trajectories towards wealth-inequality not only islands, but also more generally.

Tapping the woodpecker tree for evolutionary insight

Molecular phylogenetic studies of woodpeckers (Picidae) have generally focused on relationships within specific clades or have sampled sparsely across the family. We compared DNA sequences of six loci from 203 of the 217 recognized species of woodpeckers to construct a comprehensive tree of intrafamilial relationships. We recovered many known, but also numerous unknown, relationships among clades and species. We found, for example, that the three picine tribes are related as follows (Picini, (Campephilini, Melanerpini)) and that the genus Dinopium is paraphyletic. We used the tree to analyze rates of diversification and biogeographic patterns within the family. Diversification rate increased on two occasions during woodpecker history. We also tested diversification rates between temperate and tropical species but found no significant difference. Biogeographic analysis supported an Old World origin of the family and identified at least six independent cases of New World-Old World sister relationships. In light of the tree, we discuss how convergence, mimicry, and potential cases of hybridization have complicated woodpecker taxonomy.

Reeducation of vergence dynamics improves postural control

INTRODUCTION

The purpose was to investigate the effect of vergence reeducation on postural control, in subjects with isolated vergence disorders.

MATERIAL AND METHODS

We studied the dynamics of vergence in 19 subjects (20-44 years old) using video-oculography (Eye See Cam). On the basis of orthoptic and symptomatology assessments, ten of the subjects were diagnosed for vergence disorders then vergence eye movements were reeducated with the REMOBI method (US8851669, 5 weekly sessions lasting for 35min). Postural control was measured before and after reeducation, postural recording was done in upright stance (Dynaport), with both eyes closed or open and looking a visual target located at 2m distance.

RESULTS

After reeducation with REMOBI, the visual symptomatology faded away and the stereoacuity improved at least for some subjects; the vergence latency decreased significantly and the vergence accuracy increased significantly. In terms of posture, the Mean Power Frequency (MPF) of the body sway decreased significantly in both eyes open and eyes closed conditions. Considering all subjects together (i.e. healthy subjects and subjects with vergence disorders before the reeducation), the antero-posterior body sway (Root Mean Square A/P) was positively correlated with the visual symptomatology: the higher the visual symptomatology, the higher was the body sway.

CONCLUSION

The results bring evidence for synergy between the quality of vergence and the quality of postural control. They open a new research line that bridges the gap between neuroscience, ophthalmology-orthoptics and posturology.

Convergence and determinants of health expenditures in OECD countries

This study examines the trend and determinants of health expenditures in OECD countries over the 1975-2004 period. Based on recent developments in the economic growth literature we propose and test the hypothesis that health care expenditures in countries of similar economic development level may converge. We hypothesise that the main drivers for growth in health care costs include: aging population, technological progress and health insurance. The results reveal no evidence that health expenditures among OECD countries converge. Nevertheless, there is evidence of convergence among three sub-groups of countries. We found that the main driver of health expenditure is technological progress. Our results also suggest that health care is a (national) necessity, not a luxury good as some other studies in this field have found.

Functional integration of complex miRNA networks in central and peripheral lesion and axonal regeneration

New players are emerging in the game of peripheral and central nervous system injury since their physiopathological mechanisms remain partially elusive. These mechanisms are characterized by several molecules whose activation and/or modification following a trauma is often controlled at transcriptional level. In this scenario, microRNAs (miRNAs/miRs) have been identified as main actors in coordinating important molecular pathways in nerve or spinal cord injury (SCI). miRNAs are small non-coding RNAs whose functionality at network level is now emerging as a new level of complexity. Indeed they can act as an organized network to provide a precise control of several biological processes. Here we describe the functional synergy of some miRNAs in case of SCI and peripheral damage. In particular we show how several small RNAs can cooperate in influencing simultaneously the molecular pathways orchestrating axon regeneration, inflammation, apoptosis and remyelination. We report about the networks for which miRNA-target bindings have been experimentally demonstrated or inferred based on target prediction data: in both cases, the connection between one miRNA and its downstream pathway is derived from a validated observation or is predicted from the literature. Hence, we discuss the importance of miRNAs in some pathological processes focusing on their functional structure as participating in a cooperative and/or convergence network.

Kuhnian theory-choice and virtue convergence: Facing the base rate fallacy

Perhaps the strongest argument for scientific realism, the no-miracles-argument, has been said to commit the so-called base rate fallacy. The apparent elusiveness of the base rate of true theories has even been said to undermine the rationality of the entire realism debate. On the basis of the Kuhnian picture of theory choice, I confront this challenge by arguing that a theory is likely to be true if it possesses multiple theoretical virtues and is embraced by numerous scientists-even when the base rate converges to zero.

Fusional Amplitudes: Developing Testing Standards

PURPOSE

The stability of binocular vision depends upon good fusional amplitudes, but the clinical assessment of fusional amplitudes varies around the world. The purpose of this study was to determine whether or not there is variation in the assessment of fusional amplitudes in normal subjects. The author looked at the testing distance, the order of testing, the role of examiner encouragement, and the subject's level of alertness.

METHODS

In a prospective study using a modified crossover design, the author assessed fusional amplitudes in 99 subjects with normal eye exams. The measurements were done in two separate sessions on different days with each subject being randomized as to the order of fusional vergence testing. All subjects were assessed without and with encouragement in the first session. In the second session, all were assessed at different testing distances.

RESULTS

The author previously presented data on 50 subjects. In this expanded cohort, statistical significance was reached confirming the previous findings that convergence is significantly affected by encouragement, divergence is significantly reduced if assessed after convergence, and near amplitudes are significantly higher than distance amplitudes. Finally, there is a negative correlation between age and convergence break point.

CONCLUSIONS

The results of this study demonstrate that divergence is significantly reduced if assessed after convergence in the subject with normal binocular function. Next, convergence is significantly affected by the use of encouragement. Measurements at near produced significantly higher results for all of the convergence and divergence tests. Finally, there is a significant negative correlation between age and convergence break point. We need to develop a standard of testing fusional amplitudes so there is consistency in the clinical assessment.

Piecewise convexity of artificial neural networks

Although artificial neural networks have shown great promise in applications including computer vision and speech recognition, there remains considerable practical and theoretical difficulty in optimizing their parameters. The seemingly unreasonable success of gradient descent methods in minimizing these non-convex functions remains poorly understood. In this work we offer some theoretical guarantees for networks with piecewise affine activation functions, which have in recent years become the norm. We prove three main results. First, that the network is piecewise convex as a function of the input data. Second, that the network, considered as a function of the parameters in a single layer, all others held constant, is again piecewise convex. Third, that the network as a function of all its parameters is piecewise multi-convex, a generalization of biconvexity. From here we characterize the local minima and stationary points of the training objective, showing that they minimize the objective on certain subsets of the parameter space. We then analyze the performance of two optimization algorithms on multi-convex problems: gradient descent, and a method which repeatedly solves a number of convex sub-problems. We prove necessary convergence conditions for the first algorithm and both necessary and sufficient conditions for the second, after introducing regularization to the objective. Finally, we remark on the remaining difficulty of the global optimization problem. Under the squared error objective, we show that by varying the training data, a single rectifier neuron admits local minima arbitrarily far apart, both in objective value and parameter space.

The German East-West Mortality Difference: Two Crossovers Driven by Smoking

Before the fall of the Berlin Wall, mortality was considerably higher in the former East Germany than in West Germany. The gap narrowed rapidly after German reunification. The convergence was particularly strong for women, to the point that Eastern women aged 50-69 now have lower mortality despite lower incomes and worse overall living conditions. Prior research has shown that lower smoking rates among East German female cohorts born in the 1940s and 1950s were a major contributor to this crossover. However, after 1990, smoking behavior changed dramatically, with higher smoking intensity observed among women in the eastern part of Germany. We forecast the impact of this changing smoking behavior on East-West mortality differences and find that the higher smoking rates among younger East German cohorts will reverse their contemporary mortality advantage. Mortality forecasting methods that do not account for smoking would, perhaps misleadingly, forecast a growing mortality advantage for East German women. Experience from other countries shows that smoking can be effectively reduced by strict anti-smoking policies. Instead, East Germany is becoming an example warning of the consequences of weakening anti-smoking policies and changing behavioral norms.

Memristor standard cellular neural networks computing in the flux-charge domain

The paper introduces a class of memristor neural networks (NNs) that are characterized by the following salient features. (a) The processing of signals takes place in the flux-charge domain and is based on the time evolution of memristor charges. The processing result is given by the constant asymptotic values of charges that are stored in the memristors acting as non-volatile memories in steady state. (b) The dynamic equations describing the memristor NNs in the flux-charge domain are analogous to those describing, in the traditional voltage-current domain, the dynamics of a standard (S) cellular (C) NN, and are implemented by using a realistic model of memristors as that proposed by HP. This analogy makes it possible to use the bulk of results in the SCNN literature for designing memristor NNs to solve processing tasks in real time. Convergence of memristor NNs in the presence of multiple asymptotically stable equilibrium points is addressed and some applications to image processing tasks are presented to illustrate the real-time processing capabilities. Computing in the flux-charge domain is shown to have significant advantages with respect to computing in the voltage-current domain. One advantage is that, when a steady state is reached, currents, voltages and hence power in a memristor NN vanish, whereas memristors keep in memory the processing result. This is basically different from SCNNs for which currents, voltages and power do not vanish at a steady state, and batteries are needed to keep in memory the processing result.

Mitogenomic phylogeny of cone snails endemic to Senegal

Cone snails attain in Senegal one of their highest peaks of species diversity throughout the continental coast of Western Africa. A total of 15 endemic species have been described, all placed in the genus Lautoconus. While there is ample data regarding the morphology of the shell and the radular tooth of these species, virtually nothing is known regarding the genetic diversity and phylogenetic relationships of one of the most endangered groups of cones. In this work, we determined the complete or near-complete (only lacking the control region) mitochondrial (mt) genomes of 17 specimens representing 11 endemic species (Lautoconus belairensis, Lautoconus bruguieresi, Lautoconus cacao, Lautoconus cloveri, Lautoconus cf. echinophilus, Lautoconus guinaicus, Lautoconus hybridus, Lautoconus senegalensis, Lautoconus mercator, Lautoconus taslei, and Lautoconus unifasciatus). We also sequenced the complete mt genome of Lautoconus guanche from the Canary Islands, which has been related to the cones endemic to Senegal. All mt genomes share the same gene arrangement, which conforms to the consensus reported for Conidae, Neogastropoda and Caenogastropoda. Phylogenetic analyses using probabilistic methods recovered three major lineages, whose divergence coincided in time with sea level and ocean current changes as well as temperature fluctuations during the Messinian salinity crisis and the Plio-Pleistocene transition. Furthermore, the three lineages corresponded to distinct types of radular tooth (robust, small, and elongated), suggesting that dietary specialization could be an additional evolutionary driver in the diversification of the cones endemic to Senegal. The reconstructed phylogeny showed several cases of phenotypic convergence (cryptic species) and questions the validity of some species (ecotypes or phenotypic plasticity), both results having important taxonomic and conservation consequences.

The civic turn of immigrant integration policies in the Scandinavian welfare states

This special issue addresses the question of how to understand the civic turn within immigrant integration in the West towards programs and instruments, public discourses and political intentions, which aim to condition, incentivize, and shape through socialization immigrants into 'citizens'. Empirically, it focuses on the less studied Scandinavian cases of Sweden, Norway, and Denmark. In this introduction, we situate the contributions to this special issue within the overall debate on civic integration and convergence. We introduce the three cases, critically discuss the (liberal) convergence thesis and its descriptive and explanatory claims, and explain why studying the Scandinavian welfare states can further our understanding of the nature of the civic turn and its driving forces. Before concluding, we discuss whether civic integration policies actually work.

Convergence characteristics between a rodent, the South American lowland paca, and a ruminant, the African water chevrotain: An exemplary case study

The level of convergence between a rodent, the South American lowland paca Cuniculus paca, and a ruminant, the African water chevrotain Hyemoschus aquaticus, is analysed using 231 characteristics belonging to different biological sectors. A convergence index is established based on the degree of rarity of each characteristic in each species compared to other members of its zoological group. Although the divergent characteristics are as numerous as the convergent ones, the two species are globally similar. Convergent characteristics occur in all biological categories, but their rate varies a great deal among them. From internal anatomy and osteology, through behaviour and ecology to the external appearance of the body, convergent characteristics are all the more frequent since the biological category is directly implicated in the adaptation of animals to their external environment (lowland rainforest). However, only the individuals' characteristics are concerned and not those of their population or social organisation. This could be due to differences between the communities of terrestrial mammals to which they belong.

By more ways than one: Rapid convergence at hydrothermal vents shown by 3D anatomical reconstruction of Gigantopelta (Mollusca: Neomphalina)

Background

Extreme environments prompt the evolution of characteristic adaptations. Yet questions remain about whether radiations in extreme environments originate from a single lineage that masters a key adaptive pathway, or if the same features can arise in parallel through convergence. Species endemic to deep-sea hydrothermal vents must accommodate high temperature and low pH. The most successful vent species share a constrained pathway to successful energy exploitation: hosting symbionts. The vent-endemic gastropod genus Gigantopelta, from the Southern and Indian Oceans, shares unusual features with a co-occurring peltospirid, the ‘scaly-foot gastropod’ Chrysomallon squamiferum. Both are unusually large for the clade and share other adaptive features such as a prominent enlarged trophosome-like oesophageal gland, not found in any other vent molluscs.

Results

Transmission electron microscopy confirmed endosymbiont bacteria in the oesophageal gland of Gigantopelta, as also seen in Chrysomallon. They are the only known members of their phylum in vent ecosystems hosting internal endosymbionts; other vent molluscs host endosymbionts in or on their gills, or in the mantle cavity. A five-gene phylogenetic reconstruction demonstrated that Gigantopelta and Chrysomallon are not phylogenetically sister-taxa, despite their superficial similarity. Both genera have specialist adaptations to accommodate internalised endosymbionts, but with anatomical differences that indicate separate evolutionary origins. Hosting endosymbionts in an internal organ within the host means that all resources required by the bacteria must be supplied by the animal, rather than directly by the vent fluid. Unlike Chrysomallon, which has an enlarged oesophageal gland throughout post-settlement life, the oesophageal gland in Gigantopelta is proportionally much smaller in juveniles and the animals likely undergo a trophic shift during ontogeny. The circulatory system is hypertrophied in both but the overall size is smaller in Gigantopelta. In contrast with Chrysomallon, Gigantopelta possesses true ganglia and is gonochoristic.

Conclusions

Key anatomical differences between Gigantopelta and Chrysomallon demonstrate these two genera acquired a similar way of life through independent and convergent adaptive pathways. What appear to be the holobiont’s adaptations to an extreme environment, are driven by optimising bacteria’s access to vent nutrients. By comparing Gigantopelta and Chrysomallon, we show that metazoans are capable of rapidly and repeatedly evolving equivalent anatomical adaptations and close-knit relationships with chemoautotrophic bacteria, achieving the same end-product through parallel evolutionary trajectories.

Electronic supplementary material

The online version of this article (doi:10.1186/s12862-017-0917-z) contains supplementary material, which is available to authorized users.

Development of a lecithotrophic pilidium larva illustrates convergent evolution of trochophore-like morphology

BACKGROUND

The pilidium larva is an idiosyncrasy defining one clade of marine invertebrates, the Pilidiophora (Nemertea, Spiralia). Uniquely, in pilidial development, the juvenile worm forms from a series of isolated rudiments called imaginal discs, then erupts through and devours the larval body during catastrophic metamorphosis. A typical pilidium is planktotrophic and looks like a hat with earflaps, but pilidial diversity is much broader and includes several types of non-feeding pilidia. One of the most intriguing recently discovered types is the lecithotrophic pilidium nielseni of an undescribed species, Micrura sp. "dark" (Lineidae, Heteronemertea, Pilidiophora). The egg-shaped pilidium nielseni bears two transverse circumferential ciliary bands evoking the prototroch and telotroch of the trochophore larva found in some other spiralian phyla (e.g. annelids), but undergoes catastrophic metamorphosis similar to that of other pilidia. While it is clear that the resemblance to the trochophore is convergent, it is not clear how pilidium nielseni acquired this striking morphological similarity.

RESULTS

Here, using light and confocal microscopy, we describe the development of pilidium nielseni from fertilization to metamorphosis, and demonstrate that fundamental aspects of pilidial development are conserved. The juvenile forms via three pairs of imaginal discs and two unpaired rudiments inside a distinct larval epidermis, which is devoured by the juvenile during rapid metamorphosis. Pilidium nielseni even develops transient, reduced lobes and lappets in early stages, re-creating the hat-like appearance of a typical pilidium. Notably, its two transverse ciliary bands can be ontogenetically linked to the primary ciliary band spanning the larval lobes and lappets of the typical planktotrophic pilidium.

CONCLUSIONS

Our data shows that the development of pilidium nielseni differs remarkably from that of the trochophore, even though their larval morphology is superficially similar. Pilidium nielseni's morphological and developmental features are best explained by transition from planktotrophy to lecithotrophy in the context of pilidial development, rather than by retention of or reversal to what is often assumed to be the spiralian ancestral larval type - the trochophore. Development of pilidium nielseni is a compelling example of convergent evolution of a trochophore-like body plan within Spiralia.

VMCMC: a graphical and statistical analysis tool for Markov chain Monte Carlo traces

Background

MCMC-based methods are important for Bayesian inference of phylogeny and related parameters. Although being computationally expensive, MCMC yields estimates of posterior distributions that are useful for estimating parameter values and are easy to use in subsequent analysis. There are, however, sometimes practical difficulties with MCMC, relating to convergence assessment and determining burn-in, especially in large-scale analyses. Currently, multiple software are required to perform, e.g., convergence, mixing and interactive exploration of both continuous and tree parameters.

Results

We have written a software called VMCMC to simplify post-processing of MCMC traces with, for example, automatic burn-in estimation. VMCMC can also be used both as a GUI-based application, supporting interactive exploration, and as a command-line tool suitable for automated pipelines.

Conclusions

VMCMC is a free software available under the New BSD License. Executable jar files, tutorial manual and source code can be downloaded from https://bitbucket.org/rhali/visualmcmc/.

Electronic supplementary material

The online version of this article (doi:10.1186/s12859-017-1505-3) contains supplementary material, which is available to authorized users.

Convergence of carbon intensity in the Yangtze River Delta, China

As China's industrialization and urbanization have grown rapidly in recent years, China's CO₂ emissions rose from 3405.1799 Mt to 10,249.4630 Mt from 2000 to 2013, and it has reached the highest levels in the word since 2006. Chinese government has emphasized the importance of reducing carbon emissions and set the target of reducing carbon intensity to 60-65% of 2005 levels by 2030. Investigating the convergence of carbon intensity can identify the convergence rate, which is helpful in guiding allocations of carbon intensity reduction. The Yangtze River Delta is one of the key carbon emission regions in China, with higher urbanization levels and larger carbon emissions; thus, we employed prefecture-level panel data derived from grid data between 2000 and 2010 to examine whether the convergence of carbon intensity exists across prefecture-level cities in the Yangtze River Delta. Spatial panel data models were utilized to investigate β-convergence of carbon intensity. The results indicated that carbon intensity showed divergence during 2002-2004 and σ-convergence over other periods (2000-2002 and 2004-2010). Carbon intensity exhibited stochastic convergence, indicating that the shocks to carbon intensity relative to the average level of carbon intensity are only transitory. There was a spatial spillover effect and β-convergence of carbon intensity, suggesting that prefecture-level cities with higher carbon intensity would decrease rapidly in the Yangtze River Delta. Our results highlight the importance of considering the present state of carbon intensity, spatial factors, and socioeconomic factors such as industrial structure and economic levels during allocation planning for reducing carbon intensity.

Rare ecomorphological convergence on a complex adaptive landscape: Body size and diet mediate evolution of jaw shape in squirrels (Sciuridae)

Convergence is widely regarded as compelling evidence for adaptation, often being portrayed as evidence that phenotypic outcomes are predictable from ecology, overriding contingencies of history. However, repeated outcomes may be very rare unless adaptive landscapes are simple, structured by strong ecological and functional constraints. One such constraint may be a limitation on body size because performance often scales with size, allowing species to adapt to challenging functions by modifying only size. When size is constrained, species might adapt by changing shape; convergent shapes may therefore be common when size is limiting and functions are challenging. We examine the roles of size and diet as determinants of jaw shape in Sciuridae. As expected, size and diet have significant interdependent effects on jaw shape and ecomorphological convergence is rare, typically involving demanding diets and limiting sizes. More surprising is morphological without ecological convergence, which is equally common between and within dietary classes. Those cases, like rare ecomorphological convergence, may be consequences of evolving on an adaptive landscape shaped by many-to-many relationships between ecology and function, many-to-one relationships between form and performance, and one-to-many relationships between functionally versatile morphologies and ecology. On complex adaptive landscapes, ecological selection can yield different outcomes.

Measurement of Lytic Granule Convergence After Formation of an NK Cell Immunological Synapse

Natural killer (NK) cells contain specialized lysosome-related organelles termed lytic granules allowing them to mediate cytotoxicity against tumorigenic or virally infected target cells. NK cells polarize their lytic granules toward a target cell via the microtubule-organizing center (MTOC). Prior to that, however, lytic granules converge to the MTOC along microtubules utilizing minus-end-directed microtubule motors. Herein we describe how to visualize and quantify lytic granule convergence using confocal microscopy to gain quantitative insight into NK cell cytotoxicity and its regulation.