WorldWideScience

Sample records for exemplify convergent evolution

  1. Giant lobelias exemplify convergent evolution

    Directory of Open Access Journals (Sweden)

    Givnish Thomas J

    2010-01-01

    Full Text Available Abstract Giant lobeliads on tropical mountains in East Africa and Hawaii have highly unusual, giant-rosette growth forms that appear to be convergent on each other and on those of several independently evolved groups of Asteraceae and other families. A recent phylogenetic analysis by Antonelli, based on sequencing the widest selection of lobeliads to date, raises doubts about this paradigmatic example of convergent evolution. Here I address the kinds of evidence needed to test for convergent evolution and argue that the analysis by Antonelli fails on four points. Antonelli's analysis makes several important contributions to our understanding of lobeliad evolution and geographic spread, but his claim regarding convergence appears to be invalid. Giant lobeliads in Hawaii and Africa represent paradigmatic examples of convergent evolution.

  2. A Dome-Headed Stem Archosaur Exemplifies Convergence among Dinosaurs and Their Distant Relatives.

    Science.gov (United States)

    Stocker, Michelle R; Nesbitt, Sterling J; Criswell, Katharine E; Parker, William G; Witmer, Lawrence M; Rowe, Timothy B; Ridgely, Ryan; Brown, Matthew A

    2016-10-10

    Similarities in body plan evolution, such as wings in pterosaurs, birds, and bats or limblessness in snakes and amphisbaenians, can be recognized as classical examples of convergence among animals [1-3]. We introduce a new Triassic stem archosaur that is unexpectedly and remarkably convergent with the "dome-headed" pachycephalosaur dinosaurs that lived over 100 million years later. Surprisingly, numerous additional taxa in the same assemblage (the Otis Chalk assemblage from the Dockum Group of Texas) demonstrate the early acquisition of morphological novelties that were later convergently evolved by post-Triassic dinosaurs. As one of the most successful clades of terrestrial vertebrates, dinosaurs came to occupy an extensive morphospace throughout their diversification in the Mesozoic Era [4, 5], but their distant relatives were first to evolve many of those "dinosaurian" body plans in the Triassic Period [6-8]. Our analysis of convergence between archosauromorphs from the Triassic Period and post-Triassic archosaurs demonstrates the early and extensive exploration of morphospace captured in a single Late Triassic assemblage, and we hypothesize that many of the "novel" morphotypes interpreted to occur among archosaurs later in the Mesozoic already were in place during the initial Triassic archosauromorph, largely non-dinosaurian, radiation and only later convergently evolved in diverse dinosaurian lineages. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Industrial Evolution Through Complementary Convergence

    DEFF Research Database (Denmark)

    Frøslev Christensen, Jens

    2011-01-01

    The article addresses the dynamics through which product markets become derailed from early product life cycle (PLC)-tracks and engaged in complementary convergence with other product markets or industries. We compare and contrast the theories that can explain, respectively, the PLC...

  4. [Social psychiatry and neurobiology : A long overdue convergence exemplified by schizophrenia].

    Science.gov (United States)

    Kawohl, W; Wyss, C; Roser, P; Brüne, M; Rössler, W; Juckel, G

    2017-05-01

    The proliferation of biological psychiatry has greatly increased over the last two decades. With the possibility to carry out brain research using modern technical methods, it seemed that social influencing factors would lose importance in the development of mental diseases; however, in actual fact this does not seem to be justified. It is necessary to overcome this separation, in that social factors are incorporated into a conceptual framework in the development of mental diseases, which simultaneously also takes the results of current neurobiological research into consideration. The aims of this review article are to summarize the current state of sociopsychiatric research and to emphasize the perspectives of the biological principles and their validity with respect to the social dimensions of psychiatry, as exemplified by schizophrenic disorders. The article presents the options for a biosocial approach in social psychiatry and gives an overview of the currently available literature. There is an abundance of neurobiological research approaches, which are closely associated with sociopsychiatric topics, such as social cognition. Social psychiatry and biological psychiatry should no longer be considered as diametrically opposed subdisciplines. On the contrary, the options which could emerge from a synthesis must be used in research and clinical practice.

  5. Convergent evolution in primates and an insectivore

    Energy Technology Data Exchange (ETDEWEB)

    Boffelli, Dario; Cheng, Jan-Fang; Rubin, Edward M.

    2003-04-16

    The cardiovascular risk factor apolipoprotein(a) (apo(a)) has a puzzling distribution among mammals, its presence being limited to a subset of primates and a member of the insectivore lineage, the hedgehog. To explore the evolutionary history of apo(a), we performed extensive genomic sequence comparisons of multiple species with and without an apo(a) gene product, such as human, baboon, hedgehog, lemurand mouse. This analysis indicated that apo(a) arose independently in a subset of primates, including baboon and human, and an insectivore, the hedgehog, and was not simply lost by species lacking it. The similar structural domains shared by the hedgehog and primate apo(a) indicate that they were formed by a unique molecular mechanism involving the convergent evolution of paralogous genes in these distantspecies.

  6. Convergence

    DEFF Research Database (Denmark)

    Madsen, Ole Brun; Nielsen, Jens Frederik Dalsgaard; Schiøler, Henrik

    2002-01-01

    Convergence trends between the WAN Internet area, characterized by best effort service provision, and the real time LAN domain, with requirements for guaranteed services, are identified and discussed. A bilateral evolution is identified, where typical bulk service applications from WAN...

  7. Genome-wide signatures of convergent evolution in echolocating mammals.

    Science.gov (United States)

    Parker, Joe; Tsagkogeorga, Georgia; Cotton, James A; Liu, Yuan; Provero, Paolo; Stupka, Elia; Rossiter, Stephen J

    2013-10-10

    Evolution is typically thought to proceed through divergence of genes, proteins and ultimately phenotypes. However, similar traits might also evolve convergently in unrelated taxa owing to similar selection pressures. Adaptive phenotypic convergence is widespread in nature, and recent results from several genes have suggested that this phenomenon is powerful enough to also drive recurrent evolution at the sequence level. Where homoplasious substitutions do occur these have long been considered the result of neutral processes. However, recent studies have demonstrated that adaptive convergent sequence evolution can be detected in vertebrates using statistical methods that model parallel evolution, although the extent to which sequence convergence between genera occurs across genomes is unknown. Here we analyse genomic sequence data in mammals that have independently evolved echolocation and show that convergence is not a rare process restricted to several loci but is instead widespread, continuously distributed and commonly driven by natural selection acting on a small number of sites per locus. Systematic analyses of convergent sequence evolution in 805,053 amino acids within 2,326 orthologous coding gene sequences compared across 22 mammals (including four newly sequenced bat genomes) revealed signatures consistent with convergence in nearly 200 loci. Strong and significant support for convergence among bats and the bottlenose dolphin was seen in numerous genes linked to hearing or deafness, consistent with an involvement in echolocation. Unexpectedly, we also found convergence in many genes linked to vision: the convergent signal of many sensory genes was robustly correlated with the strength of natural selection. This first attempt to detect genome-wide convergent sequence evolution across divergent taxa reveals the phenomenon to be much more pervasive than previously recognized.

  8. Testing Convergence Versus History: Convergence Dominates Phenotypic Evolution for over 150 Million Years in Frogs.

    Science.gov (United States)

    Moen, Daniel S; Morlon, Hélène; Wiens, John J

    2016-01-01

    Striking evolutionary convergence can lead to similar sets of species in different locations, such as in cichlid fishes and Anolis lizards, and suggests that evolution can be repeatable and predictable across clades. Yet, most examples of convergence involve relatively small temporal and/or spatial scales. Some authors have speculated that at larger scales (e.g., across continents), differing evolutionary histories will prevent convergence. However, few studies have compared the contrasting roles of convergence and history, and none have done so at large scales. Here we develop a two-part approach to test the scale over which convergence can occur, comparing the relative importance of convergence and history in macroevolution using phylogenetic models of adaptive evolution. We apply this approach to data from morphology, ecology, and phylogeny from 167 species of anuran amphibians (frogs) from 10 local sites across the world, spanning ~160 myr of evolution. Mapping ecology on the phylogeny revealed that similar microhabitat specialists (e.g., aquatic, arboreal) have evolved repeatedly across clades and regions, producing many evolutionary replicates for testing for morphological convergence. By comparing morphological optima for clades and microhabitat types (our first test), we find that convergence associated with microhabitat use dominates frog morphological evolution, producing recurrent ecomorphs that together encompass all sampled species in each community in each region. However, our second test, which examines whether and how much species differ from their inferred optima, shows that convergence is incomplete: that is, phenotypes of most species are still somewhat distant from the estimated optimum for each microhabitat, seemingly because of insufficient time for more complete adaptation (an effect of history). Yet, these effects of history are related to past ecologies, and not clade membership. Overall, our study elucidates the dominant drivers of

  9. Causes of molecular convergence and parallelism in protein evolution.

    Science.gov (United States)

    Storz, Jay F

    2016-04-01

    To what extent is the convergent evolution of protein function attributable to convergent or parallel changes at the amino acid level? The mutations that contribute to adaptive protein evolution may represent a biased subset of all possible beneficial mutations owing to mutation bias and/or variation in the magnitude of deleterious pleiotropy. A key finding is that the fitness effects of amino acid mutations are often conditional on genetic background. This context dependence (epistasis) can reduce the probability of convergence and parallelism because it reduces the number of possible mutations that are unconditionally acceptable in divergent genetic backgrounds. Here, I review factors that influence the probability of replicated evolution at the molecular level.

  10. Convergent evolution between insect and mammalian audition.

    Science.gov (United States)

    Montealegre-Z, Fernando; Jonsson, Thorin; Robson-Brown, Kate A; Postles, Matthew; Robert, Daniel

    2012-11-16

    In mammals, hearing is dependent on three canonical processing stages: (i) an eardrum collecting sound, (ii) a middle ear impedance converter, and (iii) a cochlear frequency analyzer. Here, we show that some insects, such as rainforest katydids, possess equivalent biophysical mechanisms for auditory processing. Although katydid ears are among the smallest in all organisms, these ears perform the crucial stage of air-to-liquid impedance conversion and signal amplification, with the use of a distinct tympanal lever system. Further along the chain of hearing, spectral sound analysis is achieved through dispersive wave propagation across a fluid substrate, as in the mammalian cochlea. Thus, two phylogenetically remote organisms, katydids and mammals, have evolved a series of convergent solutions to common biophysical problems, despite their reliance on very different morphological substrates.

  11. Origin and convergent evolution of exendin genes.

    Science.gov (United States)

    Irwin, David M

    2012-01-01

    Exendins are secretin hormone-like peptides that are components of the toxins from two venomous lizards, Heloderma suspectum (Gila monster) and Heloderma horridium (Mexican bearded lizard). Exendins-1 and -2 are vasoactive intestinal peptide (VIP)-like, both in sequence and function, while exendins-3 and -4 are glucagon-like peptide-1 (GLP-1)-like. The evolutionary origin of these peptides, and the genes that encode them, has been unclear. Recently, genes orthologous to exendin have been identified in reptiles, birds and amphibians. Analysis of the orthologous sequences demonstrates that the Heloderma exendins diversified by gene duplication from a common exendin ancestor on the Heloderma lineage after divergence from other reptiles, including the anole lizard and Burmese python. In addition, the exendin toxin peptide sequences, but not their pro or signal peptides, have evolved very rapidly on the Heloderma lineage, likely as they adapted to their new function as toxins. Exendins-1 and -2 not only evolved rapidly but their sequences have evolved convergently upon that of VIP, resulting in a doubling of its identity with VIP, while exendins-3 and -4 have retained an ancestral property of being more GLP-1-like sequences. These results suggest that the ancestral role of exendin, which is potentially still retained in some species, had greater similarity with proglucagon-derived peptides or GIP. Copyright © 2011 Elsevier Inc. All rights reserved.

  12. Evolution of parasitism along convergent lines: from ecology to genomics.

    Science.gov (United States)

    Poulin, Robert; Randhawa, Haseeb S

    2015-02-01

    SUMMARY From hundreds of independent transitions from a free-living existence to a parasitic mode of life, separate parasite lineages have converged over evolutionary time to share traits and exploit their hosts in similar ways. Here, we first summarize the evidence that, at a phenotypic level, eukaryotic parasite lineages have all converged toward only six general parasitic strategies: parasitoid, parasitic castrator, directly transmitted parasite, trophically transmitted parasite, vector-transmitted parasite or micropredator. We argue that these strategies represent adaptive peaks, with the similarities among unrelated taxa within any strategy extending to all basic aspects of host exploitation and transmission among hosts and transcending phylogenetic boundaries. Then, we extend our examination of convergent patterns by looking at the evolution of parasite genomes. Despite the limited taxonomic coverage of sequenced parasite genomes currently available, we find some evidence of parallel evolution among unrelated parasite taxa with respect to genome reduction or compaction, and gene losses or gains. Matching such changes in parasite genomes with the broad phenotypic traits that define the convergence of parasites toward only six strategies of host exploitation is not possible at present. Nevertheless, as more parasite genomes become available, we may be able to detect clear trends in the evolution of parasitic genome architectures representing true convergent adaptive peaks, the genomic equivalents of the phenotypic strategies used by all parasites.

  13. BRICS: Evolution and Convergence of Powers

    Directory of Open Access Journals (Sweden)

    Vatanyar Saidovich Yagya

    2016-12-01

    Full Text Available Conducting of foreign policy solely by means of classical diplomacy today seems inefficient. States are supposed to use additional set of tools that have traditionally been at the confluence of soft and hard powers. Convergence of these concepts launched the emergence of such strategies, as smart power and hybrid power that we analyze as a system in relation to such a phenomenon, as BRICS. In the first part of paper we contemplate the concept of power and further expand it to the theoretical ground of each of these strategies along with the existing experience and prospects of their implementation in the BRICS countries. Systematic analysis is taken as the basis of the methodology of this paper, which allowed us to explore this theme separately for each of the BRICS countries and collectively as a system. Feasibility of a number of our provisions is confirmed by relevant case studies and analyses of the most relevant Russian and foreign literature, which results in our main conclusions. Current trends indicate that the BRICS countries are actively expanding its presence in all the key sectors of the global economy and politics. BRICS is at an early stage of implementation of own formats and tools of smart and hybrid powers, the role of which will steadily increase in the international activities of the group, adding value to its arsenal of traditional diplomacy. The potential capacity of soft, smart and hybrid powers of BRICS aims at helping countries to achieve a new level of integration and attractiveness in the eyes of the international community, and will also allow countries to strengthen their positions.

  14. Convergent sequence evolution between echolocating bats and dolphins.

    Science.gov (United States)

    Liu, Yang; Cotton, James A; Shen, Bin; Han, Xiuqun; Rossiter, Stephen J; Zhang, Shuyi

    2010-01-26

    Cases of convergent evolution - where different lineages have evolved similar traits independently - are common and have proven central to our understanding of selection. Yet convincing examples of adaptive convergence at the sequence level are exceptionally rare [1]. The motor protein Prestin is expressed in mammalian outer hair cells (OHCs) and is thought to confer high frequency sensitivity and selectivity in the mammalian auditory system [2]. We previously reported that the Prestin gene has undergone sequence convergence among unrelated lineages of echolocating bat [3]. Here we report that this gene has also undergone convergent amino acid substitutions in echolocating dolphins, which group with echolocating bats in a phylogenetic tree of Prestin. Furthermore, we find evidence that these changes were driven by natural selection. Copyright 2010 Elsevier Ltd. All rights reserved.

  15. Convergent evolution of bilaterian nerve cords.

    Science.gov (United States)

    Martín-Durán, José M; Pang, Kevin; Børve, Aina; Lê, Henrike Semmler; Furu, Anlaug; Cannon, Johanna Taylor; Jondelius, Ulf; Hejnol, Andreas

    2018-01-04

    It has been hypothesized that a condensed nervous system with a medial ventral nerve cord is an ancestral character of Bilateria. The presence of similar dorsoventral molecular patterns along the nerve cords of vertebrates, flies, and an annelid has been interpreted as support for this scenario. Whether these similarities are generally found across the diversity of bilaterian neuroanatomies is unclear, and thus the evolutionary history of the nervous system is still contentious. Here we study representatives of Xenacoelomorpha, Rotifera, Nemertea, Brachiopoda, and Annelida to assess the conservation of the dorsoventral nerve cord patterning. None of the studied species show a conserved dorsoventral molecular regionalization of their nerve cords, not even the annelid Owenia fusiformis, whose trunk neuroanatomy parallels that of vertebrates and flies. Our findings restrict the use of molecular patterns to explain nervous system evolution, and suggest that the similarities in dorsoventral patterning and trunk neuroanatomies evolved independently in Bilateria.

  16. Analysis of convergence for control problems governed by evolution ...

    African Journals Online (AJOL)

    The convergence of a scheme to minimize a class of a system of continuous optimal control problems characterized by a system of evolution equations and a system of linear inequality and equality constraints with multiplier imbedding is considered. The result is applied to some problems and the scheme is found to exhibit ...

  17. Convergence

    Science.gov (United States)

    Darcie, Thomas E.; Doverspike, Robert; Zirngibl, Martin; Korotky, Steven K.

    2005-09-01

    Call for Papers: Convergence The Journal of Optical Networking (JON) invites submissions to a special issue on Convergence. Convergence has become a popular theme in telecommunications, one that has broad implications across all segments of the industry. Continual evolution of technology and applications continues to erase lines between traditionally separate lines of business, with dramatic consequences for vendors, service providers, and consumers. Spectacular advances in all layers of optical networking-leading to abundant, dynamic, cost-effective, and reliable wide-area and local-area connections-have been essential drivers of this evolution. As services and networks continue to evolve towards some notion of convergence, the continued role of optical networks must be explored. One vision of convergence renders all information in a common packet (especially IP) format. This vision is driven by the proliferation of data services. For example, time-division multiplexed (TDM) voice becomes VoIP. Analog cable-television signals become MPEG bits streamed to digital set-top boxes. T1 or OC-N private lines migrate to Ethernet virtual private networks (VPNs). All these packets coexist peacefully within a single packet-routing methodology built on an optical transport layer that combines the flexibility and cost of data networks with telecom-grade reliability. While this vision is appealing in its simplicity and shared widely, specifics of implementation raise many challenges and differences of opinion. For example, many seek to expand the role of Ethernet in these transport networks, while massive efforts are underway to make traditional TDM networks more data friendly within an evolved but backward-compatible SDH/SONET (synchronous digital hierarchy and synchronous optical network) multiplexing hierarchy. From this common underlying theme follow many specific instantiations. Examples include the convergence at the physical, logical, and operational levels of voice and

  18. Convergent evolution of neural systems in ctenophores.

    Science.gov (United States)

    Moroz, Leonid L

    2015-02-15

    Neurons are defined as polarized secretory cells specializing in directional propagation of electrical signals leading to the release of extracellular messengers - features that enable them to transmit information, primarily chemical in nature, beyond their immediate neighbors without affecting all intervening cells en route. Multiple origins of neurons and synapses from different classes of ancestral secretory cells might have occurred more than once during ~600 million years of animal evolution with independent events of nervous system centralization from a common bilaterian/cnidarian ancestor without the bona fide central nervous system. Ctenophores, or comb jellies, represent an example of extensive parallel evolution in neural systems. First, recent genome analyses place ctenophores as a sister group to other animals. Second, ctenophores have a smaller complement of pan-animal genes controlling canonical neurogenic, synaptic, muscle and immune systems, and developmental pathways than most other metazoans. However, comb jellies are carnivorous marine animals with a complex neuromuscular organization and sophisticated patterns of behavior. To sustain these functions, they have evolved a number of unique molecular innovations supporting the hypothesis of massive homoplasies in the organization of integrative and locomotory systems. Third, many bilaterian/cnidarian neuron-specific genes and 'classical' neurotransmitter pathways are either absent or, if present, not expressed in ctenophore neurons (e.g. the bilaterian/cnidarian neurotransmitter, γ-amino butyric acid or GABA, is localized in muscles and presumed bilaterian neuron-specific RNA-binding protein Elav is found in non-neuronal cells). Finally, metabolomic and pharmacological data failed to detect either the presence or any physiological action of serotonin, dopamine, noradrenaline, adrenaline, octopamine, acetylcholine or histamine - consistent with the hypothesis that ctenophore neural systems evolved

  19. Mechanical basis of morphogenesis and convergent evolution of spiny seashells

    KAUST Repository

    Chirat, R.

    2013-03-25

    Convergent evolution is a phenomenon whereby similar traits evolved independently in not closely related species, and is often interpreted in functional terms. Spines in mollusk seashells are classically interpreted as having repeatedly evolved as a defense in response to shell-crushing predators. Here we consider the morphogenetic process that shapes these structures and underlies their repeated emergence. We develop a mathematical model for spine morphogenesis based on the mechanical interaction between the secreting mantle edge and the calcified shell edge to which the mantle adheres during shell growth. It is demonstrated that a large diversity of spine structures can be accounted for through small variations in control parameters of this natural mechanical process. This physical mechanism suggests that convergent evolution of spines can be understood through a generic morphogenetic process, and provides unique perspectives in understanding the phenotypic evolution of this second largest phylum in the animal kingdom.

  20. Evidence for widespread convergent evolution around human microsatellites.

    Directory of Open Access Journals (Sweden)

    Edward J Vowles

    2004-08-01

    Full Text Available Microsatellites are a major component of the human genome, and their evolution has been much studied. However, the evolution of microsatellite flanking sequences has received less attention, with reports of both high and low mutation rates and of a tendency for microsatellites to cluster. From the human genome we generated a database of many thousands of (AC(n flanking sequences within which we searched for common characteristics. Sequences flanking microsatellites of similar length show remarkable levels of convergent evolution, indicating shared mutational biases. These biases extend 25-50 bases either side of the microsatellite and may therefore affect more than 30% of the entire genome. To explore the extent and absolute strength of these effects, we quantified the observed convergence. We also compared homologous human and chimpanzee loci to look for evidence of changes in mutation rate around microsatellites. Most models of DNA sequence evolution assume that mutations are independent and occur randomly. Allowances may be made for sites mutating at different rates and for general mutation biases such as the faster rate of transitions over transversions. Our analysis suggests that these models may be inadequate, in that proximity to even very short microsatellites may alter the rate and distribution of mutations that occur. The elevated local mutation rate combined with sequence convergence, both of which we find evidence for, also provide a possible resolution for the apparently contradictory inferences of mutation rates in microsatellite flanking sequences.

  1. Genomic basis for the convergent evolution of electric organs

    Science.gov (United States)

    Gallant, Jason R.; Traeger, Lindsay L.; Volkening, Jeremy D.; Moffett, Howell; Chen, Po-Hao; Novina, Carl D.; Phillips, George N.; Anand, Rene; Wells, Gregg B.; Pinch, Matthew; Güth, Robert; Unguez, Graciela A.; Albert, James S.; Zakon, Harold H.; Samanta, Manoj P.; Sussman, Michael R.

    2017-01-01

    Little is known about the genetic basis of convergent traits that originate repeatedly over broad taxonomic scales. The myogenic electric organ has evolved six times in fishes to produce electric fields used in communication, navigation, predation, or defense. We have examined the genomic basis of the convergent anatomical and physiological origins of these organs by assembling the genome of the electric eel (Electrophorus electricus) and sequencing electric organ and skeletal muscle transcriptomes from three lineages that have independently evolved electric organs. Our results indicate that, despite millions of years of evolution and large differences in the morphology of electric organ cells, independent lineages have leveraged similar transcription factors and developmental and cellular pathways in the evolution of electric organs. PMID:24970089

  2. Convergent evolution of insect hearing organs from a preadaptive structure

    OpenAIRE

    Lakes-Harlan, R.; lting, H. St; Stumpner, A.

    1999-01-01

    Flies of the taxon Emblemasomatini (Sarcophagidae: Diptera) independently evolved an ear with the same anatomy and location as the Ormiini (Tachinidae: Diptera). Both ears represent a first case of convergent evolution of homologous insect ears, which raises the question for a preadaptation. Physiological and anatomical data indicate a preadaptive-sound-insensitive, but vibration-sensitive scolopidial chordotonal organ in non-hearing flies. As selective pressure for the evolutionary transform...

  3. Elucidation of gibberellin biosynthesis in bacteria reveals convergent evolution

    OpenAIRE

    Nett, Ryan S.; Montanares, Mariana; Marcassa, Ariana; Lu, Xuan; Nagel, Raimund; Charles, Trevor C.; Hedden, Peter; Rojas, Maria Cecilia; Peters, Reuben J.

    2016-01-01

    Gibberellins (GAs) are crucial phytohormones involved in many aspects of plant growth and development, including plant-microbe interactions, which has led to GA production by plant-associated fungi and bacteria as well. While the GA biosynthetic pathways in plants and fungi have been elucidated and found to have independently arisen through convergent evolution, little has been uncovered about GA biosynthesis in bacteria. Some nitrogen-fixing/symbiotic, legume-associated rhizobia, including B...

  4. SETI in the light of cosmic convergent evolution

    Science.gov (United States)

    Flores Martinez, Claudio L.

    2014-11-01

    Theodosius Dobzhansky, one of the founding fathers of the modern evolutionary synthesis, once famously stated that ;nothing makes sense in biology except in the light of evolution;. Here it will be argued that nothing in astrobiology makes sense except in the light of ;Cosmic Convergent Evolution; (CCE). This view of life contends that natural selection is a universal force of nature that leads to the emergence of similarly adapted life forms in analogous planetary biospheres. Although SETI historically preceded the rise of astrobiology that we have witnessed in the recent decade, one of its main tenets from the beginning was the convergence of life on a cosmic scale toward intelligent behavior and subsequent communication via technological means. The question of cultural convergence in terms of symbolic exchange, language and scientific capabilities between advanced interstellar civilizations has been the subject of ongoing debate. However, at the core of the search for extraterrestrial intelligence lies in essence a biological problem since even post-biological extraterrestrial intelligences must have had an origin based on self-replicating biopolymers. Thus, SETI assumes a propensity of the Universe towards biogenesis in accordance with CCE, a new evolutionary concept which posits the multiple emergence of life across the Cosmos. Consequently, we have to wonder about the biophilic properties the Universe apparently exhibits, as well as to try to find an encompassing theory that is able to explain this ;fine-tuning; in naturalistic terms. The aims of this paper are as follows: 1) to emphasize the importance of convergent evolution in astrobiology and ongoing SETI research; 2) to introduce novel and biology-centered cosmological ideas such as the ;Selfish Biocosm Hypothesis; and the ;Evo Devo Universe; as valuable arguments in theorizing about the origin and nature of extraterrestrial intelligence and 3) to synthesize these findings within an emerging post

  5. Convergence

    Science.gov (United States)

    Darcie, Thomas E.; Doverspike, Robert; Zirngibl, Martin; Korotky, Steven K.

    2005-01-01

    .p {padding-bottom:6px} Call for Papers: Convergence Guest Editors: Thomas E. Darcie, University of Victoria Robert Doverspike, AT&T Martin Zirngibl, Lucent Technologies Coordinating Associate Editor: Steven K. Korotky, Lucent Technologies The Journal of Optical Networking (JON) invites submissions to a special issue on Convergence. Convergence has become a popular theme in telecommunications, one that has broad implications across all segments of the industry. Continual evolution of technology and applications continues to erase lines between traditionally separate lines of business, with dramatic consequences for vendors, service providers, and consumers. Spectacular advances in all layers of optical networking-leading to abundant, dynamic, cost-effective, and reliable wide-area and local-area connections-have been essential drivers of this evolution. As services and networks continue to evolve towards some notion of convergence, the continued role of optical networks must be explored. One vision of convergence renders all information in a common packet (especially IP) format. This vision is driven by the proliferation of data services. For example, time-division multiplexed (TDM) voice becomes VoIP. Analog cable-television signals become MPEG bits streamed to digital set-top boxes. T1 or OC-N private lines migrate to Ethernet virtual private networks (VPNs). All these packets coexist peacefully within a single packet-routing methodology built on an optical transport layer that combines the flexibility and cost of data networks with telecom-grade reliability. While this vision is appealing in its simplicity and shared widely, specifics of implementation raise many challenges and differences of opinion. For example, many seek to expand the role of Ethernet in these transport networks, while massive efforts are underway to make traditional TDM networks more data friendly within an evolved but backward-compatible SDH/SONET (synchronous digital hierarchy and

  6. Convergent evolution in mechanical design of lamnid sharks and tunas.

    Science.gov (United States)

    Donley, Jeanine M; Sepulveda, Chugey A; Konstantinidis, Peter; Gemballa, Sven; Shadwick, Robert E

    2004-05-06

    The evolution of 'thunniform' body shapes in several different groups of vertebrates, including whales, ichthyosaurs and several species of large pelagic fishes supports the view that physical and hydromechanical demands provided important selection pressures to optimize body design for locomotion during vertebrate evolution. Recognition of morphological similarities between lamnid sharks (the most well known being the great white and the mako) and tunas has led to a general expectation that they also have converged in their functional design; however, no quantitative data exist on the mechanical performance of the locomotor system in lamnid sharks. Here we examine the swimming kinematics, in vivo muscle dynamics and functional morphology of the force-transmission system in a lamnid shark, and show that the evolutionary convergence in body shape and mechanical design between the distantly related lamnids and tunas is much more than skin deep; it extends to the depths of the myotendinous architecture and the mechanical basis for propulsive movements. We demonstrate that not only have lamnids and tunas converged to a much greater extent than previously known, but they have also developed morphological and functional adaptations in their locomotor systems that are unlike virtually all other fishes.

  7. Terminology Evolution and Translation: Specificity of Referent & User’s Epistemic Continuum Exemplified in Islamic Terms

    Directory of Open Access Journals (Sweden)

    Omar A. S. Al-Shabab

    2016-01-01

    Full Text Available In the dynamics of environmental context, the referent of a linguistic sign changes, but the sign persists as a verbal symbol. Since a technical term strictly evokes one referent, it may lack in specificity due to the ever-changing reality, resulting in homonymy, overlap, and a semantic continuum based on designating by necessity. In addition to the elements of reference theory, the criteria for technical terms postulate the user, whose authority and responsibility are necessary for the term to function as a specific designator. The centrality of the user, translator or otherwise, has hermeneutic and linguistic implications for the evolution of terminology, because it stipulates that terminological meaning and usage are dependent on the user’s conscious knowledge, a condition that leads to the recognition of a user epistemic continuum parallel to the semantic necessity continuum. Ideally, a term should be universally specific in reference, and its user should be epistemologically empowered and ethically responsible.

  8. Remarkable convergent evolution in specialized parasitic Thecostraca (Crustacea

    Directory of Open Access Journals (Sweden)

    Crandall Keith A

    2009-04-01

    Full Text Available Abstract Background The Thecostraca are arguably the most morphologically and biologically variable group within the Crustacea, including both suspension feeders (Cirripedia: Thoracica and Acrothoracica and parasitic forms (Cirripedia: Rhizocephala, Ascothoracida and Facetotecta. Similarities between the metamorphosis found in the Facetotecta and Rhizocephala suggests a common evolutionary origin, but until now no comprehensive study has looked at the basic evolution of these thecostracan groups. Results To this end, we collected DNA sequences from three nuclear genes [18S rRNA (2,305, 28S rRNA (2,402, Histone H3 (328] and 41 larval characters in seven facetotectans, five ascothoracidans, three acrothoracicans, 25 rhizocephalans and 39 thoracicans (ingroup and 12 Malacostraca and 10 Copepoda (outgroup. Maximum parsimony, maximum likelihood and Bayesian analyses showed the Facetotecta, Ascothoracida and Cirripedia each as monophyletic. The better resolved and highly supported DNA maximum likelihood and morphological-DNA Bayesian analysis trees depicted the main phylogenetic relationships within the Thecostraca as (Facetotecta, (Ascothoracida, (Acrothoracica, (Rhizocephala, Thoracica. Conclusion Our analyses indicate a convergent evolution of the very similar and highly reduced slug-shaped stages found during metamorphosis of both the Rhizocephala and the Facetotecta. This provides a remarkable case of convergent evolution and implies that the advanced endoparasitic mode of life known from the Rhizocephala and strongly indicated for the Facetotecta had no common origin. Future analyses are needed to determine whether the most recent common ancestor of the Thecostraca was free-living or some primitive form of ectoparasite.

  9. Remarkable convergent evolution in specialized parasitic Thecostraca (Crustacea)

    Science.gov (United States)

    Pérez-Losada, Marcos; Høeg, Jens T; Crandall, Keith A

    2009-01-01

    Background The Thecostraca are arguably the most morphologically and biologically variable group within the Crustacea, including both suspension feeders (Cirripedia: Thoracica and Acrothoracica) and parasitic forms (Cirripedia: Rhizocephala, Ascothoracida and Facetotecta). Similarities between the metamorphosis found in the Facetotecta and Rhizocephala suggests a common evolutionary origin, but until now no comprehensive study has looked at the basic evolution of these thecostracan groups. Results To this end, we collected DNA sequences from three nuclear genes [18S rRNA (2,305), 28S rRNA (2,402), Histone H3 (328)] and 41 larval characters in seven facetotectans, five ascothoracidans, three acrothoracicans, 25 rhizocephalans and 39 thoracicans (ingroup) and 12 Malacostraca and 10 Copepoda (outgroup). Maximum parsimony, maximum likelihood and Bayesian analyses showed the Facetotecta, Ascothoracida and Cirripedia each as monophyletic. The better resolved and highly supported DNA maximum likelihood and morphological-DNA Bayesian analysis trees depicted the main phylogenetic relationships within the Thecostraca as (Facetotecta, (Ascothoracida, (Acrothoracica, (Rhizocephala, Thoracica)))). Conclusion Our analyses indicate a convergent evolution of the very similar and highly reduced slug-shaped stages found during metamorphosis of both the Rhizocephala and the Facetotecta. This provides a remarkable case of convergent evolution and implies that the advanced endoparasitic mode of life known from the Rhizocephala and strongly indicated for the Facetotecta had no common origin. Future analyses are needed to determine whether the most recent common ancestor of the Thecostraca was free-living or some primitive form of ectoparasite. PMID:19374762

  10. Evolution of the Converged NGN Service Platforms Towards Future Networks

    Directory of Open Access Journals (Sweden)

    Eugen Mikóczy

    2011-03-01

    Full Text Available This article presents a comparison of main characteristics of the Next Generation Networks (NGN and Future Generation Internet (FGI. The aim is to discuss and compare two approaches to Future Networks (FN and services: the evolution of NGN, and the revolutionary approach of a new FGI. We present both frameworks from the services point of view as they are delivered to the end-user, as well as from the architectural point of view. We compare selected properties of both approaches to explain commonalities and differences. Their challenges are similar: managing the quality of experience, mobility, security, scalability and providing openness to applications. Based on this comparison, we evaluate possible areas for future convergence in the approach of the two architectures to the Future Network concept. Our analysis shows that despite their different backgrounds, the internet’s FGI and telco’s NGN are not that different after all. The convergence of the two approaches therefore seems the only logical way forward.

  11. Convergence, Consilience, and the Evolution of Temperate Deciduous Forests.

    Science.gov (United States)

    Edwards, Erika J; Chatelet, David S; Chen, Bo-Chang; Ong, Jin Yao; Tagane, Shuichiro; Kanemitsu, Hironobu; Tagawa, Kazuki; Teramoto, Kentaro; Park, Brian; Chung, Kuo-Fang; Hu, Jer-Ming; Yahara, Tetsukazu; Donoghue, Michael J

    2017-08-01

    The deciduous habit of northern temperate trees and shrubs provides one of the most obvious examples of convergent evolution, but how did it evolve? Hypotheses based on the fossil record posit that deciduousness evolved first in response to drought or darkness and preadapted certain lineages as cold climates spread. An alternative is that evergreens first established in freezing environments and later evolved the deciduous habit. We monitored phenological patterns of 20 species of Viburnum spanning tropical, lucidophyllous (subtropical montane and warm temperate), and cool temperate Asian forests. In lucidophyllous forests, all viburnums were evergreen plants that exhibited coordinated leaf flushes with the onset of the rainy season but varied greatly in the timing of leaf senescence. In contrast, deciduous species exhibited tight coordination of both flushing and senescence, and we found a perfect correlation between the deciduous habit and prolonged annual freezing. In contrast to previous stepwise hypotheses, a consilience of independent lines of evidence supports a lockstep model in which deciduousness evolved in situ, in parallel, and concurrent with a gradual cooling climate. A pervasive selective force combined with the elevated evolutionary accessibility of a particular response may explain the massive convergence of adaptive strategies that characterizes the world's biomes.

  12. Elucidation of gibberellin biosynthesis in bacteria reveals convergent evolution.

    Science.gov (United States)

    Nett, Ryan S; Montanares, Mariana; Marcassa, Ariana; Lu, Xuan; Nagel, Raimund; Charles, Trevor C; Hedden, Peter; Rojas, Maria Cecilia; Peters, Reuben J

    2017-01-01

    Gibberellins (GAs) are crucial phytohormones involved in many aspects of plant growth and development, including plant-microbe interactions, which has led to GA production by plant-associated fungi and bacteria as well. While the GA biosynthetic pathways in plants and fungi have been elucidated and found to have arisen independently through convergent evolution, little has been uncovered about GA biosynthesis in bacteria. Some nitrogen-fixing, symbiotic, legume-associated rhizobia, including Bradyrhizobium japonicum-the symbiont of soybean-and Sinorhizobium fredii-a broad-host-nodulating species-contain a putative GA biosynthetic operon, or gene cluster. Through functional characterization of five unknown genes, we demonstrate that this operon encodes the enzymes necessary to produce GA9, thereby elucidating bacterial GA biosynthesis. The distinct nature of these enzymes indicates that bacteria have independently evolved a third biosynthetic pathway for GA production. Furthermore, our results also reveal a central biochemical logic that is followed in all three convergently evolved GA biosynthetic pathways.

  13. Convergent Evolution of Rumen Microbiomes in High-Altitude Mammals.

    Science.gov (United States)

    Zhang, Zhigang; Xu, Dongming; Wang, Li; Hao, Junjun; Wang, Jinfeng; Zhou, Xin; Wang, Weiwei; Qiu, Qiang; Huang, Xiaodan; Zhou, Jianwei; Long, Ruijun; Zhao, Fangqing; Shi, Peng

    2016-07-25

    Studies of genetic adaptation, a central focus of evolutionary biology, most often focus on the host's genome and only rarely on its co-evolved microbiome. The Qinghai-Tibetan Plateau (QTP) offers one of the most extreme environments for the survival of human and other mammalian species. Yaks (Bos grunniens) and Tibetan sheep (T-sheep) (Ovis aries) have adaptations for living in this harsh high-altitude environment, where nomadic Tibetan people keep them primarily for food and livelihood [1]. Adaptive evolution affects energy-metabolism-related genes in a way that helps these ruminants live at high altitude [2, 3]. Herein, we report convergent evolution of rumen microbiomes for energy harvesting persistence in two typical high-altitude ruminants, yaks and T-sheep. Both ruminants yield significantly lower levels of methane and higher yields of volatile fatty acids (VFAs) than their low-altitude relatives, cattle (Bos taurus) and ordinary sheep (Ovis aries). Ultra-deep metagenomic sequencing reveals significant enrichment in VFA-yielding pathways of rumen microbial genes in high-altitude ruminants, whereas methanogenesis pathways show enrichment in the cattle metagenome. Analyses of RNA transcriptomes reveal significant upregulation in 36 genes associated with VFA transport and absorption in the ruminal epithelium of high-altitude ruminants. Our study provides novel insights into the contributions of microbiomes to adaptive evolution in mammals and sheds light on the biological control of greenhouse gas emissions from livestock enteric fermentation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Convergent evolution of escape from hepaciviral antagonism in primates.

    Directory of Open Access Journals (Sweden)

    Maulik R Patel

    Full Text Available The ability to mount an interferon response on sensing viral infection is a critical component of mammalian innate immunity. Several viruses directly antagonize viral sensing pathways to block activation of the host immune response. Here, we show that recurrent viral antagonism has shaped the evolution of the host protein MAVS--a crucial component of the viral-sensing pathway in primates. From sequencing and phylogenetic analyses of MAVS from 21 simian primates, we found that MAVS has evolved under strong positive selection. We focused on how this positive selection has shaped MAVS' susceptibility to Hepatitis C virus (HCV. We functionally tested MAVS proteins from diverse primate species for their ability to resist antagonism by HCV, which uses its protease NS3/4A to cleave human MAVS. We found that MAVS from multiple primates are resistant to inhibition by the HCV protease. This resistance maps to single changes within the protease cleavage site in MAVS, which protect MAVS from getting cleaved by the HCV protease. Remarkably, most of these changes have been independently acquired at a single residue 506 that evolved under positive selection. We show that "escape" mutations lower affinity of the NS3 protease for MAVS and allow it to better restrict HCV replication. We further show that NS3 proteases from all other primate hepaciviruses, including the highly divergent GBV-A and GBV-C viruses, are functionally similar to HCV. We conclude that convergent evolution at residue 506 in multiple primates has resulted in escape from antagonism by hepaciviruses. Our study provides a model whereby insights into the ancient history of viral infections in primates can be gained using extant host and virus genes. Our analyses also provide a means by which primates might clear infections by extant hepaciviruses like HCV.

  15. Grasping convergent evolution in syngnathids: a unique tale of tails.

    Science.gov (United States)

    Neutens, C; Adriaens, D; Christiaens, J; De Kegel, B; Dierick, M; Boistel, R; Van Hoorebeke, L

    2014-06-01

    Seahorses and pipehorses both possess a prehensile tail, a unique characteristic among teleost fishes, allowing them to grasp and hold onto substrates such as sea grasses. Although studies have focused on tail grasping, the pattern of evolutionary transformations that made this possible is poorly understood. Recent phylogenetic studies show that the prehensile tail evolved independently in different syngnathid lineages, including seahorses, Haliichthys taeniophorus and several types of so-called pipehorses. This study explores the pattern that characterizes this convergent evolution towards a prehensile tail, by comparing the caudal musculoskeletal organization, as well as passive bending capacities in pipefish (representing the ancestral state), pipehorse, seahorse and H. taeniophorus. To study the complex musculoskeletal morphology, histological sectioning, μCT-scanning and phase contrast synchrotron scanning were combined with virtual 3D-reconstructions. Results suggest that the independent evolution towards tail grasping in syngnathids reflects at least two quite different strategies in which the ancestral condition of a heavy plated and rigid system became modified into a highly flexible one. Intermediate skeletal morphologies (between the ancestral condition and seahorses) could be found in the pygmy pipehorses and H. taeniophorus, which are phylogenetically closely affiliated with seahorses. This study suggests that the characteristic parallel myoseptal organization as already described in seahorse (compared with a conical organization in pipefish and pipehorse) may not be a necessity for grasping, but represents an apomorphy for seahorses, as this pattern is not found in other syngnathid species possessing a prehensile tail. One could suggest that the functionality of grasping evolved before the specialized, parallel myoseptal organization seen in seahorses. However, as the grasping system in pipehorses is a totally different one, this cannot be

  16. Convergent evolution of escape from hepaciviral antagonism in primates.

    Science.gov (United States)

    Patel, Maulik R; Loo, Yueh-Ming; Horner, Stacy M; Gale, Michael; Malik, Harmit S

    2012-01-01

    The ability to mount an interferon response on sensing viral infection is a critical component of mammalian innate immunity. Several viruses directly antagonize viral sensing pathways to block activation of the host immune response. Here, we show that recurrent viral antagonism has shaped the evolution of the host protein MAVS--a crucial component of the viral-sensing pathway in primates. From sequencing and phylogenetic analyses of MAVS from 21 simian primates, we found that MAVS has evolved under strong positive selection. We focused on how this positive selection has shaped MAVS' susceptibility to Hepatitis C virus (HCV). We functionally tested MAVS proteins from diverse primate species for their ability to resist antagonism by HCV, which uses its protease NS3/4A to cleave human MAVS. We found that MAVS from multiple primates are resistant to inhibition by the HCV protease. This resistance maps to single changes within the protease cleavage site in MAVS, which protect MAVS from getting cleaved by the HCV protease. Remarkably, most of these changes have been independently acquired at a single residue 506 that evolved under positive selection. We show that "escape" mutations lower affinity of the NS3 protease for MAVS and allow it to better restrict HCV replication. We further show that NS3 proteases from all other primate hepaciviruses, including the highly divergent GBV-A and GBV-C viruses, are functionally similar to HCV. We conclude that convergent evolution at residue 506 in multiple primates has resulted in escape from antagonism by hepaciviruses. Our study provides a model whereby insights into the ancient history of viral infections in primates can be gained using extant host and virus genes. Our analyses also provide a means by which primates might clear infections by extant hepaciviruses like HCV.

  17. Convergent evolution of social hybridogenesis in Messor harvester ants.

    Science.gov (United States)

    Romiguier, Jonathan; Fournier, Axel; Yek, Sze Huei; Keller, Laurent

    2017-02-01

    Sexual reproduction generally requires no more than two partners. Here, we show convergent evolution of social hybridogenesis, a reproductive system requiring three reproductive partners in harvester ants. In this unorthodox reproductive system, two distinct genetic lineages live in sympatry and queens have to mate with males of their own lineage to produce queens along with males of the alternative lineage to produce workers. Using a large transcriptomic data set of nine species, we show that social hybridogenesis evolved at least three times independently in the genus Messor. Moreover, a study of 13 populations of Messor barbarus revealed that this mode of reproduction is fixed in the whole range of this ecologically dominant species. Finally, we show that workers can produce males carrying genes of the two genetic lineages, raising the possibility of rare gene flow between lineages contributing to the long-term maintenance of pairs of interdependent lineages. These results emphasize the evolutionary importance of social hybridogenesis, a major transition possibly linked to the peculiar ecology of harvester ants. © 2016 John Wiley & Sons Ltd.

  18. Reaction mechanism of azoreductases suggests convergent evolution with quinone oxidoreductases.

    Science.gov (United States)

    Ryan, Ali; Wang, Chan-Ju; Laurieri, Nicola; Westwood, Isaac; Sim, Edith

    2010-08-01

    Azoreductases are involved in the bioremediation by bacteria of azo dyes found in waste water. In the gut flora, they activate azo pro-drugs, which are used for treatment of inflammatory bowel disease, releasing the active component 5-aminosalycilic acid. The bacterium P. aeruginosa has three azoreductase genes, paAzoR1, paAzoR2 and paAzoR3, which as recombinant enzymes have been shown to have different substrate specificities. The mechanism of azoreduction relies upon tautomerisation of the substrate to the hydrazone form. We report here the characterization of the P. aeruginosa azoreductase enzymes, including determining their thermostability, cofactor preference and kinetic constants against a range of their favoured substrates. The expression levels of these enzymes during growth of P. aeruginosa are altered by the presence of azo substrates. It is shown that enzymes that were originally described as azoreductases, are likely to act as NADH quinone oxidoreductases. The low sequence identities observed among NAD(P)H quinone oxidoreductase and azoreductase enzymes suggests convergent evolution.

  19. Convergent evolution of hemoglobin switching in jawed and jawless vertebrates.

    Science.gov (United States)

    Rohlfing, Kim; Stuhlmann, Friederike; Docker, Margaret F; Burmester, Thorsten

    2016-02-01

    During development, humans and other jawed vertebrates (Gnathostomata) express distinct hemoglobin genes, resulting in different hemoglobin tetramers. Embryonic and fetal hemoglobin have higher oxygen affinities than the adult hemoglobin, sustaining the oxygen demand of the developing organism. Little is known about the expression of hemoglobins during development of jawless vertebrates (Agnatha). We identified three hemoglobin switches in the life cycle of the sea lamprey. Three hemoglobin genes are specifically expressed in the embryo, four genes in the filter feeding larva (ammocoete), and nine genes correspond to the adult hemoglobin chains. During the development from the parasitic to the reproductive adult, the composition of hemoglobin changes again, with a massive increase of chain aHb1. A single hemoglobin chain is expressed constitutively in all stages. We further showed the differential expression of other globin genes: Myoglobin 1 is most highly expressed in the reproductive adult, myoglobin 2 expression peaks in the larva. Globin X1 is restricted to the embryo; globin X2 was only found in the reproductive adult. Cytoglobin is expressed at low levels throughout the life cycle. Because the hemoglobins of jawed and jawless vertebrates evolved independently from a common globin ancestor, hemoglobin switching must also have evolved convergently in these taxa. Notably, the ontogeny of sea lamprey hemoglobins essentially recapitulates their phylogeny, with the embryonic hemoglobins emerging first, followed by the evolution of larval and adult hemoglobins.

  20. Comparative genomics reveals convergent evolution between the bamboo-eating giant and red pandas.

    Science.gov (United States)

    Hu, Yibo; Wu, Qi; Ma, Shuai; Ma, Tianxiao; Shan, Lei; Wang, Xiao; Nie, Yonggang; Ning, Zemin; Yan, Li; Xiu, Yunfang; Wei, Fuwen

    2017-01-31

    Phenotypic convergence between distantly related taxa often mirrors adaptation to similar selective pressures and may be driven by genetic convergence. The giant panda (Ailuropoda melanoleuca) and red panda (Ailurus fulgens) belong to different families in the order Carnivora, but both have evolved a specialized bamboo diet and adaptive pseudothumb, representing a classic model of convergent evolution. However, the genetic bases of these morphological and physiological convergences remain unknown. Through de novo sequencing the red panda genome and improving the giant panda genome assembly with added data, we identified genomic signatures of convergent evolution. Limb development genes DYNC2H1 and PCNT have undergone adaptive convergence and may be important candidate genes for pseudothumb development. As evolutionary responses to a bamboo diet, adaptive convergence has occurred in genes involved in the digestion and utilization of bamboo nutrients such as essential amino acids, fatty acids, and vitamins. Similarly, the umami taste receptor gene TAS1R1 has been pseudogenized in both pandas. These findings offer insights into genetic convergence mechanisms underlying phenotypic convergence and adaptation to a specialized bamboo diet.

  1. Convergence and divergence in the evolution of aquatic birds.

    OpenAIRE

    Van Tuinen, M.; Butvill, D. B.; Kirsch, J A; Hedges, S.B.

    2001-01-01

    Aquatic birds exceed other terrestrial vertebrates in the diversity of their adaptations to aquatic niches. For many species this has created difficulty in understanding their evolutionary origin and, in particular, for the flamingos, hamerkop, shoebill and pelecaniforms. Here, new evidence from nuclear and mitochondrial DNA sequences and DNA-DNA hybridization data indicates extensive morphological convergence and divergence in aquatic birds. Among the unexpected findings is a grouping of fla...

  2. Convergent Evolution of Health Information Management and Health Informatics

    Science.gov (United States)

    Gibson, C. J.; Abrams, K.

    2015-01-01

    Summary Clearly defined boundaries are disappearing among the activities, sources, and uses of health care data and information managed by health information management (HIM) and health informatics (HI) professionals. Definitions of the professional domains and scopes of practice for HIM and HI are converging with the proliferation of information and communication technologies in health care settings. Convergence is changing both the roles that HIM and HI professionals serve in their organizations as well as the competencies necessary for training future professionals. Many of these changes suggest a blurring of roles and responsibilities with increasingly overlapping curricula, job descriptions, and research agendas. Blurred lines in a highly competitive market create confusion for students and employers. In this essay, we provide some perspective on the changing landscape and suggest a course for the future. First we review the evolving definitions of HIM and HI. We next compare the current domains and competencies, review the characteristics as well as the education and credentialing of both disciplines, and examine areas of convergence. Given the current state, we suggest a path forward to strengthen the contributions HIM and HI professionals and educators make to the evolving health care environment. PMID:25848421

  3. Genome-Wide Convergence during Evolution of Mangroves from Woody Plants.

    Science.gov (United States)

    Xu, Shaohua; He, Ziwen; Guo, Zixiao; Zhang, Zhang; Wyckoff, Gerald J; Greenberg, Anthony; Wu, Chung-I; Shi, Suhua

    2017-04-01

    When living organisms independently invade a new environment, the evolution of similar phenotypic traits is often observed. An interesting but contentious issue is whether the underlying molecular biology also converges in the new habitat. Independent invasions of tropical intertidal zones by woody plants, collectively referred to as mangrove trees, represent some dramatic examples. The high salinity, hypoxia, and other stressors in the new habitat might have affected both genomic features and protein structures. Here, we developed a new method for detecting convergence at conservative Sites (CCS) and applied it to the genomic sequences of mangroves. In simulations, the CCS method drastically reduces random convergence at rapidly evolving sites as well as falsely inferred convergence caused by the misinferences of the ancestral character. In mangrove genomes, we estimated ∼400 genes that have experienced convergence over the background level of convergence in the nonmangrove relatives. The convergent genes are enriched in pathways related to stress response and embryo development, which could be important for mangroves' adaptation to the new habitat. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. Convergence and divergence in the evolution of aquatic birds.

    Science.gov (United States)

    Van Tuinen, M; Butvill, D B; Kirsch, J A; Hedges, S B

    2001-07-07

    Aquatic birds exceed other terrestrial vertebrates in the diversity of their adaptations to aquatic niches. For many species this has created difficulty in understanding their evolutionary origin and, in particular, for the flamingos, hamerkop, shoebill and pelecaniforms. Here, new evidence from nuclear and mitochondrial DNA sequences and DNA-DNA hybridization data indicates extensive morphological convergence and divergence in aquatic birds. Among the unexpected findings is a grouping of flamingos and grebes, species which otherwise show no resemblance. These results suggest that the traditional characters used to unite certain aquatic groups, such as totipalmate feet, foot-propelled diving and long legs, evolved more than once and that organismal change in aquatic birds has proceeded at a faster pace than previously recognized.

  5. Evolution of the Converged NGN Service Platforms Towards Future Networks

    NARCIS (Netherlands)

    Mikóczy, E.; Kotuliak, I.; Deventer, M.O. van

    2011-01-01

    This article presents a comparison of main characteristics of the Next Generation Networks (NGN) and Future Generation Internet (FGI). The aim is to discuss and compare two approaches to Future Networks (FN) and services: the evolution of NGN, and the revolutionary approach of a new FGI. We present

  6. Convergent Phenotypic Evolution despite Contrasting Demographic Histories in the Fauna of White Sands.

    Science.gov (United States)

    Rosenblum, Erica Bree; Parent, Christine E; Diepeveen, Eveline T; Noss, Clay; Bi, Ke

    2017-08-01

    When are evolutionary outcomes predictable? Cases of convergent evolution can shed light on when, why, and how different species exhibit shared evolutionary trajectories. In particular, studying diverse species in a common environment can illuminate how different factors facilitate or constrain adaptive evolution. Here we integrate studies of pattern and process in the fauna at White Sands (New Mexico) to understand the determinants of convergent evolution. Numerous animal species at White Sands exhibit phenotypic convergence in response to a novel-and shared-selective environment: geologically young gypsum dunes. We synthesize 15 years of research on White Sands lizards to assess the contribution of natural selection, genetic architecture, and population demography to patterns of phenotypic evolution. We also present new data for two species of White Sands arthropods, Ammobaenetes arenicolus and Habronattus ustulatus. Overall, we find dramatic phenotypic convergence across diverse species at White Sands. Although the direction of phenotypic response is parallel, the magnitude of phenotypic response varies among species. We also find that species exhibit strikingly different demographic patterns across the ecotone. The species with the most genetic structure between White Sands and dark-soil populations generally exhibit the least phenotypic divergence, suggesting population demography as a key modulator of adaptation. Comparative studies are particularly important for understanding the determinants of convergence in natural systems.

  7. Evolution of substrate recognition sites (SRSs) in cytochromes P450 from Apiaceae exemplified by the CYP71AJ subfamily

    DEFF Research Database (Denmark)

    Dueholm, Bjørn; Krieger, Celia; Drew, Damian

    2015-01-01

    Background: Large proliferations of cytochrome P450 encoding genes resulting from gene duplications can be termed as 'blooms', providing genetic material for the genesis and evolution of biosynthetic pathways. Furanocoumarins are allelochemicals produced by many of the species in Apiaceaous plants...... belonging to the Apioideae subfamily of Apiaceae and have been described as being involved in the defence reaction against phytophageous insects. Results: A bloom in the cytochromes P450 CYP71AJ subfamily has been identified, showing at least 2 clades and 6 subclades within the CYP71AJ subfamily. Two...

  8. Predictors of orbital convergence in primates: a test of the snake detection hypothesis of primate evolution.

    Science.gov (United States)

    Wheeler, Brandon C; Bradley, Brenda J; Kamilar, Jason M

    2011-09-01

    Traditional explanations for the evolution of high orbital convergence and stereoscopic vision in primates have focused on how stereopsis might have aided early primates in foraging or locomoting in an arboreal environment. It has recently been suggested that predation risk by constricting snakes was the selective force that favored the evolution of orbital convergence in early primates, and that later exposure to venomous snakes favored further degrees of convergence in anthropoid primates. Our study tests this snake detection hypothesis (SDH) by examining whether orbital convergence among extant primates is indeed associated with the shared evolutionary history with snakes or the risk that snakes pose for a given species. We predicted that orbital convergence would be higher in species that: 1) have a longer history of sympatry with venomous snakes, 2) are likely to encounter snakes more frequently, 3) are less able to detect or deter snakes due to group size effects, and 4) are more likely to be preyed upon by snakes. Results based on phylogenetically independent contrasts do not support the SDH. Orbital convergence shows no relationship to the shared history with venomous snakes, likelihood of encountering snakes, or group size. Moreover, those species less likely to be targeted as prey by snakes show significantly higher values of orbital convergence. Although an improved ability to detect camouflaged snakes, along with other cryptic stimuli, is likely a consequence of increased orbital convergence, this was unlikely to have been the primary selective force favoring the evolution of stereoscopic vision in primates. Copyright © 2011 Elsevier Ltd. All rights reserved.

  9. Demographic Evolution in Romania – Convergence or Peripherisation?

    Directory of Open Access Journals (Sweden)

    Adriana Veronica Litra

    2006-02-01

    Full Text Available Romania began its demographic transition about one century later than the developed countries. We put the blame of this gap on the delayed economic, social and political development in comparison with the Western Europe. But also, it could not be forgotten the shift from a population forced and subdue by the totalitary regime, to a free people to decide when to have a child or how large should be the family. During transition, Romania has pointed many negative demographic evolutions, as compared with the other european countries. It may be said that the transition in Romania over the period 1990-2004 adjusted the classical pattern of demographic evolution. Not fully felt at this moment, we will probably find ourselves few decades later older, less, deprived of skilled labor force and unbalanced as gender ratio.

  10. The Convergence Paradox: The Global Evolution of National Innovation Systems

    OpenAIRE

    Fulvio Castellacci; Jose Miguel Natera

    2015-01-01

    This paper presents an empirical analysis of the global evolution of national innovation systems. The study identifies six main dimensions, three of which are related to the techno-economic domain (innovation and technological capabilities, openness and infrastructures), while the other three refer to countries’ socio-institutional system (education, political institutions and social cohesion). The empirical analysis describes the cross-country distribution of a large number of indicators mea...

  11. Functional traits, convergent evolution, and periodic tables of niches.

    Science.gov (United States)

    Winemiller, Kirk O; Fitzgerald, Daniel B; Bower, Luke M; Pianka, Eric R

    2015-08-01

    Ecology is often said to lack general theories sufficiently predictive for applications. Here, we examine the concept of a periodic table of niches and feasibility of niche classification schemes from functional trait and performance data. Niche differences and their influence on ecological patterns and processes could be revealed effectively by first performing data reduction/ordination analyses separately on matrices of trait and performance data compiled according to logical associations with five basic niche 'dimensions', or aspects: habitat, life history, trophic, defence and metabolic. Resultant patterns then are integrated to produce interpretable niche gradients, ordinations and classifications. Degree of scheme periodicity would depend on degrees of niche conservatism and convergence causing species clustering across multiple niche dimensions. We analysed a sample data set containing trait and performance data to contrast two approaches for producing niche schemes: species ordination within niche gradient space, and niche categorisation according to trait-value thresholds. Creation of niche schemes useful for advancing ecological knowledge and its applications will depend on research that produces functional trait and performance datasets directly related to niche dimensions along with criteria for data standardisation and quality. As larger databases are compiled, opportunities will emerge to explore new methods for data reduction, ordination and classification. © 2015 The Authors. Ecology Letters published by CNRS and John Wiley & Sons Ltd.

  12. PLANT EVOLUTION. Convergent evolution of strigolactone perception enabled host detection in parasitic plants.

    Science.gov (United States)

    Conn, Caitlin E; Bythell-Douglas, Rohan; Neumann, Drexel; Yoshida, Satoko; Whittington, Bryan; Westwood, James H; Shirasu, Ken; Bond, Charles S; Dyer, Kelly A; Nelson, David C

    2015-07-31

    Obligate parasitic plants in the Orobanchaceae germinate after sensing plant hormones, strigolactones, exuded from host roots. In Arabidopsis thaliana, the α/β-hydrolase D14 acts as a strigolactone receptor that controls shoot branching, whereas its ancestral paralog, KAI2, mediates karrikin-specific germination responses. We observed that KAI2, but not D14, is present at higher copy numbers in parasitic species than in nonparasitic relatives. KAI2 paralogs in parasites are distributed into three phylogenetic clades. The fastest-evolving clade, KAI2d, contains the majority of KAI2 paralogs. Homology models predict that the ligand-binding pockets of KAI2d resemble D14. KAI2d transgenes confer strigolactone-specific germination responses to Arabidopsis thaliana. Thus, the KAI2 paralogs D14 and KAI2d underwent convergent evolution of strigolactone recognition, respectively enabling developmental responses to strigolactones in angiosperms and host detection in parasites. Copyright © 2015, American Association for the Advancement of Science.

  13. REVIEW: Epistasis and dominance in the emergence of catalytic function as exemplified by the evolution of plant terpene synthases.

    Science.gov (United States)

    Cheema, Jitender; Faraldos, Juan A; O'Maille, Paul E

    2017-02-01

    Epistasis, the interaction between mutations and the genetic background, is a pervasive force in evolution that is difficult to predict yet derives from a simple principle - biological systems are interconnected. Therefore, one effect may be intimately linked to another, hence interdependent. Untangling epistatic interactions between and within genes is a vibrant area of research. Deriving a mechanistic understanding of epistasis is a major challenge. Particularly, elucidating how epistasis can attenuate the effects of otherwise dominant mutations that control phenotypes. Using the emergence of terpene cyclization in specialized metabolism as an excellent example, this review describes the process of discovery and interpretation of dominance and epistasis in relation to current efforts. Specifically, we outline experimental approaches to isolating epistatic networks of mutations in protein structure, formally quantifying epistatic interactions, then building biochemical models with chemical mechanisms in efforts to achieve an understanding of the physical basis for epistasis. From these models we describe informed conjectures about past evolutionary events that underlie the emergence, divergence and specialization of terpene synthases to illustrate key principles of the constraining forces of epistasis in enzyme function. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  14. Phylogenetic Origins of Biological Cognition : Convergent Patterns in the Early Evolution of Learning

    NARCIS (Netherlands)

    van Duijn, Marc

    2017-01-01

    Various forms of elementary learning have recently been discovered in organisms lacking a nervous system, such as protists, fungi and plants. This finding has fundamental implications for how we view the role of convergent evolution in biological cognition. In this article, I first review the

  15. Latent homology and convergent regulatory evolution underlies the repeated emergence of yeasts

    NARCIS (Netherlands)

    Nagy, László G; Ohm, Robin A; Kovács, Gábor M; Floudas, Dimitrios; Riley, Robert; Gácser, Attila; Sipiczki, Mátyás; Davis, John M; Doty, Sharon L; de Hoog, G Sybren; Lang, B Franz; Spatafora, Joseph W; Martin, Francis M; Grigoriev, Igor V; Hibbett, David S

    Convergent evolution is common throughout the tree of life, but the molecular mechanisms causing similar phenotypes to appear repeatedly are obscure. Yeasts have arisen in multiple fungal clades, but the genetic causes and consequences of their evolutionary origins are unknown. Here we show that the

  16. Latent homology and convergent regulatory evolution underlies the repeated emergence of yeasts

    NARCIS (Netherlands)

    Nagy, L.G.; Ohm, R.A.; Kovács, G.M.; Floudas, D.; Riley, R.; Gácser, A.; Sipiczki, M.; Davis, J.M.; Doty, S.L.; de Hoog, G.S.; Lang, B.F.; Spatafora, J.W.; Martin, F.M.; Grigoriev, I.V.; Hibbett, D.S.

    2014-01-01

    Convergent evolution is common throughout the tree of life, but the molecular mechanisms causing similar phenotypes to appear repeatedly are obscure. Yeasts have arisen in multiple fungal clades, but the genetic causes and consequences of their evolutionary origins are unknown. Here we show that the

  17. Macrobothriotaenia ficta (Cestoda: Proteocephalidea), a parasite of sunbeam snake (Xenopeltis unicolor): example of convergent evolution

    Czech Academy of Sciences Publication Activity Database

    Scholz, Tomáš; de Chambrier, A.; Kuchta, Roman; Littlewood, D. T. J.; Waeschenbach, A.

    2013-01-01

    Roč. 3640, č. 3 (2013), s. 485-499 ISSN 1175-5326 R&D Projects: GA ČR GAP506/12/1632 Institutional support: RVO:60077344 Keywords : morphology * scolex * multilocus phylogenetic analysis * convergent evolution * redescription * Ophidia * Xenopeltidae * South-East Asia Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.060, year: 2013

  18. EMPIRICAL WEIGHTED MODELLING ON INTER-COUNTY INEQUALITIES EVOLUTION AND TO TEST ECONOMICAL CONVERGENCE IN ROMANIA

    Directory of Open Access Journals (Sweden)

    Natalia\tMOROIANU‐DUMITRESCU

    2015-06-01

    Full Text Available During the last decades, the regional convergence process in Europe has attracted a considerable interest as a highly significant issue, especially after EU enlargement with the New Member States from Central and Eastern Europe. The most usual empirical approaches are using the β- and σ-convergence, originally developed by a series of neo-classical models. Up-to-date, the EU integration process was proven to be accompanied by an increase of the regional inequalities. In order to determine the existence of a similar increase of the inequalities between the administrative counties (NUTS3 included in the NUTS2 and NUTS1 regions of Romania, this paper provides an empirical modelling of economic convergence allowing to evaluate the level and evolution of the inter-regional inequalities over more than a decade period lasting from 1995 up to 2011. The paper presents the results of a large cross-sectional study of σ-convergence and weighted coefficient of variation, using GDP and population data obtained from the National Institute of Statistics of Romania. Both graphical representation including non-linear regression and the associated tables summarizing numerical values of the main statistical tests are demonstrating the impact of pre- accession policy on the economic development of all Romanian NUTS types. The clearly emphasised convergence in the middle time subinterval can be correlated with the pre-accession drastic changes on economic, political and social level, and with the opening of the Schengen borders for Romanian labor force in 2002.

  19. Convergent evolution and adaptation of Pseudomonas aeruginosa within patients with cystic fibrosis

    DEFF Research Database (Denmark)

    Marvig, Rasmus Lykke; Madsen Sommer, Lea Mette; Molin, Søren

    2015-01-01

    fibrosis. Our analysis of 36 P. aeruginosa lineages identified convergent molecular evolution in 52 genes. This list of genes suggests a role in host adaptation for remodeling of regulatory networks and central metabolism, acquisition of antibiotic resistance and loss of extracellular virulence factors....... Furthermore, we find an ordered succession of mutations in key regulatory networks. Accordingly, mutations in downstream transcriptional regulators were contingent upon mutations in upstream regulators, suggesting that remodeling of regulatory networks might be important in adaptation. The characterization...... of genes involved in host adaptation may help in predicting bacterial evolution in patients with cystic fibrosis and in the design of future intervention strategies....

  20. Complex dynamics underlie the evolution of imperfect wing pattern convergence in butterflies.

    Science.gov (United States)

    Finkbeiner, Susan D; Briscoe, Adriana D; Mullen, Sean P

    2017-04-01

    Adaptive radiation is characterized by rapid diversification that is strongly associated with ecological specialization. However, understanding the evolutionary mechanisms fueling adaptive diversification requires a detailed knowledge of how natural selection acts at multiple life-history stages. Butterflies within the genus Adelpha represent one of the largest and most diverse butterfly lineages in the Neotropics. Although Adelpha species feed on an extraordinary diversity of larval hosts, convergent evolution is widespread in this group, suggesting that selection for mimicry may contribute to adaptive divergence among species. To investigate this hypothesis, we conducted predation studies in Costa Rica using artificial butterfly facsimiles. Specifically, we predicted that nontoxic, palatable Adelpha species that do not feed on host plants in the family Rubiaceae would benefit from sharing a locally convergent wing pattern with the presumably toxic Rubiaceae-feeding species via reduced predation. Contrary to expectations, we found that the presumed mimic was attacked significantly more than its locally convergent model at a frequency paralleling attack rates on both novel and palatable prey. Although these data reveal the first evidence for protection from avian predators by the supposed toxic, Rubiaceae-feeding Adelpha species, we conclude that imprecise mimetic patterns have high costs for Batesian mimics in the tropics. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

  1. Toward a Predictive Framework for Convergent Evolution: Integrating Natural History, Genetic Mechanisms, and Consequences for the Diversity of Life.

    Science.gov (United States)

    Agrawal, Anurag A

    2017-08-01

    A charm of biology as a scientific discipline is the diversity of life. Although this diversity can make laws of biology challenging to discover, several repeated patterns and general principles govern evolutionary diversification. Convergent evolution, the independent evolution of similar phenotypes, has been at the heart of one approach to understand generality in the evolutionary process. Yet understanding when and why organismal traits and strategies repeatedly evolve has been a central challenge. These issues were the focus of the American Society of Naturalists Vice Presidential Symposium in 2016 and are the subject of this collection of articles. Although naturalists have long made inferences about convergent evolution and its importance, there has been confusion in the interpretation of the pattern of convergence. Does convergence primarily indicate adaptation or constraint? How often should convergence be expected? Are there general principles that would allow us to predict where and when and by what mechanisms convergent evolution should occur? What role does natural history play in advancing our understanding of general evolutionary principles? In this introductory article, I address these questions, review several generalizations about convergent evolution that have emerged over the past 15 years, and present a framework for advancing the study and interpretation of convergence. Perhaps the most important emerging conclusion is that the genetic mechanisms of convergent evolution are phylogenetically conserved; that is, more closely related species tend to share the same genetic basis of traits, even when independently evolved. Finally, I highlight how the articles in this special issue further develop concepts, methodologies, and case studies at the frontier of our understanding of the causes and consequences of convergent evolution.

  2. Unexpected Convergent Evolution of Nasal Domes between Pleistocene Bovids and Cretaceous Hadrosaur Dinosaurs.

    Science.gov (United States)

    O'Brien, Haley D; Faith, J Tyler; Jenkins, Kirsten E; Peppe, Daniel J; Plummer, Thomas W; Jacobs, Zenobia L; Li, Bo; Joannes-Boyau, Renaud; Price, Gilbert; Feng, Yue-Xing; Tryon, Christian A

    2016-02-22

    The fossil record provides tangible, historical evidence for the mode and operation of evolution across deep time. Striking patterns of convergence are some of the strongest examples of these operations, whereby, over time, similar environmental and/or behavioral pressures precipitate similarity in form and function between disparately related taxa. Here we present fossil evidence for an unexpected convergence between gregarious plant-eating mammals and dinosaurs. Recent excavations of Late Pleistocene deposits on Rusinga Island, Kenya, have uncovered a catastrophic assemblage of the wildebeest-like bovid Rusingoryx atopocranion. Previously known from fragmentary material, these new specimens reveal large, hollow, osseous nasal crests: a craniofacial novelty for mammals that is remarkably comparable to the nasal crests of lambeosaurine hadrosaur dinosaurs. Using adult and juvenile material from this assemblage, as well as computed tomographic imaging, we investigate this convergence from morphological, developmental, functional, and paleoenvironmental perspectives. Our detailed analyses reveal broad parallels between R. atopocranion and basal Lambeosaurinae, suggesting that osseous nasal crests may require a highly specific combination of ontogeny, evolution, and environmental pressures in order to develop. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. A Convergent Differential Evolution Algorithm with Hidden Adaptation Selection for Engineering Optimization

    Directory of Open Access Journals (Sweden)

    Zhongbo Hu

    2014-01-01

    Full Text Available Many improved differential Evolution (DE algorithms have emerged as a very competitive class of evolutionary computation more than a decade ago. However, few improved DE algorithms guarantee global convergence in theory. This paper developed a convergent DE algorithm in theory, which employs a self-adaptation scheme for the parameters and two operators, that is, uniform mutation and hidden adaptation selection (haS operators. The parameter self-adaptation and uniform mutation operator enhance the diversity of populations and guarantee ergodicity. The haS can automatically remove some inferior individuals in the process of the enhancing population diversity. The haS controls the proposed algorithm to break the loop of current generation with a small probability. The breaking probability is a hidden adaptation and proportional to the changes of the number of inferior individuals. The proposed algorithm is tested on ten engineering optimization problems taken from IEEE CEC2011.

  4. Convergent evolution of RFX transcription factors and ciliary genes predated the origin of metazoans

    Directory of Open Access Journals (Sweden)

    Chen Nansheng

    2010-05-01

    Full Text Available Abstract Background Intraflagellar transport (IFT genes, which are critical for the development and function of cilia and flagella in metazoans, are tightly regulated by the Regulatory Factor X (RFX transcription factors (TFs. However, how and when their evolutionary relationship was established remains unknown. Results We have identified evidence suggesting that RFX TFs and IFT genes evolved independently and their evolution converged before the first appearance of metazoans. Both ciliary genes and RFX TFs exist in all metazoans as well as some unicellular eukaryotes. However, while RFX TFs and IFT genes are found simultaneously in all sequenced metazoan genomes, RFX TFs do not co-exist with IFT genes in most pre-metazoans and thus do not regulate them in these organisms. For example, neither the budding yeast nor the fission yeast possesses cilia although both have well-defined RFX TFs. Conversely, most unicellular eukaryotes, including the green alga Chlamydomonas reinhardtii, have typical cilia and well conserved IFT genes but lack RFX TFs. Outside of metazoans, RFX TFs and IFT genes co-exist only in choanoflagellates including M. brevicollis, and only one fungus Allomyces macrogynus of the 51 sequenced fungus genomes. M. brevicollis has two putative RFX genes and a full complement of ciliary genes. Conclusions The evolution of RFX TFs and IFT genes were independent in pre-metazoans. We propose that their convergence in evolution, or the acquired transcriptional regulation of IFT genes by RFX TFs, played a pivotal role in the establishment of metazoan.

  5. Convergent evolution of mechanically optimal locomotion in aquatic invertebrates and vertebrates.

    Directory of Open Access Journals (Sweden)

    Rahul Bale

    2015-04-01

    Full Text Available Examples of animals evolving similar traits despite the absence of that trait in the last common ancestor, such as the wing and camera-type lens eye in vertebrates and invertebrates, are called cases of convergent evolution. Instances of convergent evolution of locomotory patterns that quantitatively agree with the mechanically optimal solution are very rare. Here, we show that, with respect to a very diverse group of aquatic animals, a mechanically optimal method of swimming with elongated fins has evolved independently at least eight times in both vertebrate and invertebrate swimmers across three different phyla. Specifically, if we take the length of an undulation along an animal's fin during swimming and divide it by the mean amplitude of undulations along the fin length, the result is consistently around twenty. We call this value the optimal specific wavelength (OSW. We show that the OSW maximizes the force generated by the body, which also maximizes swimming speed. We hypothesize a mechanical basis for this optimality and suggest reasons for its repeated emergence through evolution.

  6. Convergent Evolution of Unique Morphological Adaptations to a Subterranean Environment in Cave Millipedes (Diplopoda).

    Science.gov (United States)

    Liu, Weixin; Golovatch, Sergei; Wesener, Thomas; Tian, Mingyi

    2017-01-01

    Animal life in caves has fascinated researchers and the public alike because of the unusual and sometimes bizarre morphological adaptations observed in numerous troglobitic species. Despite their worldwide diversity, the adaptations of cave millipedes (Diplopoda) to a troglobitic lifestyle have rarely been examined. In this study, morphological characters were analyzed in species belonging to four different orders (Glomerida, Polydesmida, Chordeumatida, and Spirostreptida) and six different families (Glomeridae, Paradoxosomatidae, Polydesmidae, Haplodesmidae, Megalotylidae, and Cambalopsidae) that represent the taxonomic diversity of class Diplopoda. We focused on the recently discovered millipede fauna of caves in southern China. Thirty different characters were used to compare cave troglobites and epigean species within the same genera. A character matrix was created to analyze convergent evolution of cave adaptations. Males and females were analyzed independently to examine sex differences in cave adaptations. While 10 characters only occurred in a few phylogenetic groups, 20 characters were scored for in all families. Of these, four characters were discovered to have evolved convergently in all troglobitic millipedes. The characters that represented potential morphological cave adaptations in troglobitic species were: (1) a longer body; (2) a lighter body color; (3) elongation of the femora; and (4) elongation of the tarsi of walking legs. Surprisingly, female, but not male, antennae were more elongated in troglobites than in epigean species. Our study clearly shows that morphological adaptations have evolved convergently in different, unrelated millipede orders and families, most likely as a direct adaptation to cave life.

  7. Biomechanical evidence for convergent evolution of the invasive growth process among fungi and oomycete water molds.

    Science.gov (United States)

    Money, Nicholas P; Davis, Christopher M; Ravishankar, J P

    2004-09-01

    Diverse microorganisms traditionally called fungi are recognized as members of two kingdoms: mushroom-forming species and their relatives in the Fungi, and oomycete water molds in the Stramenopila. Phylogenetic analysis suggests that these kingdoms diverged early in the evolution of eukaryotes. The phylogenetic detachment of the fungi and oomycetes is reflected in radical differences in their biochemistry, cell structure, and development. In terms of their biological activities, however, they show great similarity, because both groups form colonies of filamentous hyphae that invade and decompose solid food sources. Here we present biomechanical evidence of the convergent evolution of the invasive growth process in these microorganisms. Using miniature strain gauges to measure the forces exerted by single hyphae, we show that the hyphae of species in both kingdoms exert up to 2 atmospheres of hydrostatic pressure as they extend at their tips. No other eukaryotes have adopted this process for meeting their nutritional needs.

  8. Convergent evolution of argonaute-2 slicer antagonism in two distinct insect RNA viruses.

    Directory of Open Access Journals (Sweden)

    Joël T van Mierlo

    Full Text Available RNA interference (RNAi is a major antiviral pathway that shapes evolution of RNA viruses. We show here that Nora virus, a natural Drosophila pathogen, is both a target and suppressor of RNAi. We detected viral small RNAs with a signature of Dicer-2 dependent small interfering RNAs in Nora virus infected Drosophila. Furthermore, we demonstrate that the Nora virus VP1 protein contains RNAi suppressive activity in vitro and in vivo that enhances pathogenicity of recombinant Sindbis virus in an RNAi dependent manner. Nora virus VP1 and the viral suppressor of RNAi of Cricket paralysis virus (1A antagonized Argonaute-2 (AGO2 Slicer activity of RNA induced silencing complexes pre-loaded with a methylated single-stranded guide strand. The convergent evolution of AGO2 suppression in two unrelated insect RNA viruses highlights the importance of AGO2 in antiviral defense.

  9. Searching for convergent evolution in manganese superoxidase dismutase using hydrophobic cluster analysis

    Directory of Open Access Journals (Sweden)

    Heng Xiang

    2014-06-01

    Full Text Available There are numerous examples of convergent evolution in nature. Major ecological adaptations such as flight, loss of limbs in vertebrates, pesticide resistance, adaptation to a parasitic way of life, etc., have all evolved more than once, as seen by their analogous functions in separate taxa. But what about protein evolution? Does the environment have a strong enough influence on intracellular processes that enzymes and other functional proteins play, to evolve similar functional roles separately in different organisms? Manganese Superoxide Dismutase (MnSOD is a manganesedependant metallo-enzyme which plays a crucial role in protecting cells from anti-oxidative stress by eliminating reactive (superoxide oxygen species. It is a ubiquitous housekeeping enzyme found in nearly all organisms. In this study we compare phylogenies based on MnSOD protein sequences to those based on scores from Hydrophobic Cluster Analysis (HCA. We calculated HCA similarity values for each pair of taxa to obtain a pair-wise distance matrix. A UPGMA tree based on the HCA distance matrix and a common tree based on the primary protein sequence for MnSOD was constructed. Differences between these two trees within animals, enterobacteriaceae, planctomycetes and cyanobacteria are presented and cited as possible examples of convergence. We note that several residue changes result in changes in hydrophobicity at positions which apparently are under the effect of positive selection.

  10. Deep sequencing identifies genetic heterogeneity and recurrent convergent evolution in chronic lymphocytic leukemia.

    Science.gov (United States)

    Ojha, Juhi; Ayres, Jackline; Secreto, Charla; Tschumper, Renee; Rabe, Kari; Van Dyke, Daniel; Slager, Susan; Shanafelt, Tait; Fonseca, Rafael; Kay, Neil E; Braggio, Esteban

    2015-01-15

    Recent high-throughput sequencing and microarray studies have characterized the genetic landscape and clonal complexity of chronic lymphocytic leukemia (CLL). Here, we performed a longitudinal study in a homogeneously treated cohort of 12 patients, with sequential samples obtained at comparable stages of disease. We identified clonal competition between 2 or more genetic subclones in 70% of the patients with relapse, and stable clonal dynamics in the remaining 30%. By deep sequencing, we identified a high reservoir of genetic heterogeneity in the form of several driver genes mutated in small subclones underlying the disease course. Furthermore, in 2 patients, we identified convergent evolution, characterized by the combination of genetic lesions affecting the same genes or copy number abnormality in different subclones. The phenomenon affects multiple CLL putative driver abnormalities, including mutations in NOTCH1, SF3B1, DDX3X, and del(11q23). This is the first report documenting convergent evolution as a recurrent event in the CLL genome. Furthermore, this finding suggests the selective advantage of specific combinations of genetic lesions for CLL pathogenesis in a subset of patients. © 2015 by The American Society of Hematology.

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

    Science.gov (United States)

    Soghigian, John; Andreadis, Theodore G; Livdahl, Todd P

    2017-12-19

    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. 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. 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.

  12. Convergence and remarkably consistent constraint in the evolution of carnivore skull shape.

    Science.gov (United States)

    Wroe, Stephen; Milne, Nicholas

    2007-05-01

    Phenotypic similarities between distantly related marsupials and placentals are commonly presented as examples of convergence and support for the role of adaptive evolution in shaping morphological and ecological diversity. Here we compare skull shape in a wide range of carnivoran placentals (Carnivora) and nonherbivorous marsupials using a three-dimensional (3-D) geometric morphometric approach. Morphological and ecological diversity among extant carnivorans is considerably greater than is evident in the marsupial order Dasyuromorphia with which they have most commonly been compared. To examine convergence across a wider, but broadly comparable range of feeding ecologies, a dataset inclusive of nondasyuromorphian marsupials and extinct taxa representing morphotypes no longer present was assembled. We found support for the adaptive paradigm, with correlations between morphology, feeding behavior, and bite force, although skull shape better predicted feeding ecology in the phylogenetically diverse marsupial sample than in carnivorans. However, we also show that remarkably consistent but differing constraints have influenced the evolution of cranial shape in both groups. These differences between carnivorans and marsupials, which correlate with brain size and bite force, are maintained across the full gamut of morphologies and feeding categories, from small insectivores and omnivores to large meat-specialists.

  13. Macrobothriotaenia ficta (Cestoda: Proteocephalidea), a parasite of sunbeam snake (Xenopeltis unicolor): example of convergent evolution.

    Science.gov (United States)

    Scholz, Tomáš; De Chambrier, Alain; Kuchta, Roman; Littlewood, D Timothy J; Waeschenbach, Andrea

    2013-01-01

    The poorly known proteocephalidean cestode Macrobothriotaenia ficta (Meggitt, 1931) from the sunbeam snake Xenopeltis unicolor (Ophidia: Xenopeltidae) is redescribed on the basis of re-examination of its type specimens from Burma (Myanmar), and vouchers from Thailand and Vietnam. The peculiar morphology of the scolex, which is formed by four pedunculate lobe-bearing pincer-shaped suckers, is described for the first time using scanning electron microscopy. In scolex morphology, M. ficta closely resembles phyllobothriidean cestodes, parasites of elasmobranchs. However, this similarity does not reflect phylogenetic relatedness of these cestodes but instead presents an example of convergent morphological evolution of attachment organs of unrelated groups of cestodes that parasitize different groups of vertebrates. Besides scolex morphology, the genus is characterised by the possession of a very large cirrus-sac, which may reach up to the midline of proglottides, few testes (less than 60), vitelline follicles limited to the dorsal side of proglottides, a large vaginal sphincter, and eggs with a three-layered embryophore covered with rounded projections. Numerous errors in the diagnosis of M. ficta, which appeared in the literature as a result of uncritical compilation of data without examination of original material, are corrected. Multilocus phylogenetic analysis of nuclear ribosomal RNA genes ssr- and lsr-DNA and mitochondrial genes rrnL and cox1 place this species among other snake-parasitizing proteocephalideans of the genus Ophiotaenia. The convergent evolution of scolex morphology across distantly related taxa is discussed.

  14. Chemodiversity in Selaginella: a reference system for parallel and convergent metabolic evolution in terrestrial plants

    Directory of Open Access Journals (Sweden)

    Jing-Ke eWeng

    2013-05-01

    Full Text Available Early plants began colonizing the terrestrial earth approximately 450 million years ago. Their success on land has been partially attributed to the evolution of specialized metabolic systems from core metabolic pathways, the former yielding structurally and functionally diverse chemicals to cope with a myriad of biotic and abiotic pressures. Over the past two decades, functional genomics, primarily focused on flowering plants, has begun cataloging the biosynthetic players underpinning assorted classes of plant specialized metabolites. However, the molecular mechanisms enriching specialized metabolic pathways during land plant evolution remain largely unexplored. Selaginella is an extant lycopodiophyte genus representative of an ancient lineage of tracheophytes. Notably, the lycopodiophytes diverged from euphyllophytes over 400 million years ago. The recent completion of the whole-genome sequence of an extant lycopodiophyte, Selaginella moellendorffii, provides new genomic and biochemical resources for studying metabolic evolution in vascular plants. 400 million years of independent evolution of lycopodiophytes and euphyllophytes resulted in numerous metabolic traits confined to each lineage. Surprisingly, a cadre of specialized metabolites, generally accepted to be restricted to seed plants, have been identified in Selaginella. Initial work suggested that Selaginella lacks obvious catalytic homologues known to be involved in the biosynthesis of well-studied specialized metabolites in seed plants. Therefore, these initial functional analyses suggest that the same chemical phenotypes arose independently more commonly than anticipated from our conventional understanding of divergent evolution of metabolism. Notably, the emergence of analogous and homologous catalytic machineries through convergent and parallel evolution, respectively, seems to have occurred repeatedly in different plant lineages.

  15. Floral evolution in the Annonaceae: hypotheses of homeotic mutations and functional convergence.

    Science.gov (United States)

    Saunders, Richard M K

    2010-08-01

    The recent publication of hypotheses explaining the homeotic control of floral organ identity together with the availability of increasingly comprehensive and well-resolved molecular phylogenies presents an ideal opportunity for reassessing current knowledge of floral diversity and evolution in the Annonaceae. This review summarizes currently available information on selected aspects of floral structure and function, including: changes in the number of perianth whorls and the number of perianth parts per whorl; the evolution of sympetaly; the diversity and evolution of pollination chambers (with a novel classification of seven main structural forms of floral chamber based on the different arrangement, size and shape of petals); the evolution of perianth glands; floral unisexuality and hypotheses explaining the unexpectedly high frequency of occurrence of androdioecy; the origin and possible function of inner and outer staminodes; the evolution of stamen connective diversity and theca septation; and the origin of 'true' syncarpy and functionally equivalent extragynoecial compita. In each case, current ideas on the origin, evolution and function are discussed. The information presented in this review enables two main conclusions to be drawn. The first is that changes in the homeotic control of floral organ identity may have had a profound impact on floral structure in several disparate lineages in the family. This is most obvious in Fenerivia, in which a centrifugal shift of floral organ identity has occurred, and in Dasymaschalon, in which a reverse (centripetal) shift has occurred. Other genera that have gained or lost entire perianth whorls are likely to have undergone similar homeotic changes. Attention is also drawn to the extensive functional convergence in Annonaceae flowers, with widespread homoplasy in many characters that have previously been emphasized in higher-level classifications.

  16. Bayesian phylogeny of sucrose transporters: Ancient origins, differential expansion and convergent evolution in monocots and dicots

    Directory of Open Access Journals (Sweden)

    Duo ePeng

    2014-11-01

    Full Text Available Sucrose transporters (SUTs are essential for the export and efficient movement of sucrose from source leaves to sink organs in plants. The angiosperm SUT family was previously classified into three or four distinct groups, Types I, II (subgroup IIB and III, with dicot-specific Type I and monocot-specific Type IIB functioning in phloem loading. To shed light on the underlying drivers of SUT evolution, Bayesian phylogenetic inference was undertaken using 41 sequenced plant genomes, including seven basal lineages at key evolutionary junctures. Our analysis supports four phylogenetically and structurally distinct SUT subfamilies, originating from two ancient groups (AG1 and AG2 that diverged early during terrestrial colonization. In both AG1 and AG2, multiple intron acquisition events in the progenitor vascular plant established the gene structures of modern SUTs. Tonoplastic Type III and plasmalemmal Type II represent evolutionarily conserved descendants of AG1 and AG2, respectively. Type I and Type IIB were previously thought to evolve after the dicot-monocot split. We show, however, that divergence of Type I from Type III SUT predated basal angiosperms, likely associated with evolution of vascular cambium and phloem transport. Type I SUT was subsequently lost in monocots along with vascular cambium, and independent evolution of Type IIB coincided with modified monocot vasculature. Both Type I and Type IIB underwent lineage-specific expansion. In multiple unrelated taxa, the newly-derived SUTs exhibit biased expression in reproductive tissues, suggesting a functional link between phloem loading and reproductive fitness. Convergent evolution of Type I and Type IIB for SUT function in phloem loading and reproductive organs supports the idea that differential vascular development in dicots and monocots is a strong driver for SUT family evolution in angiosperms.

  17. Convergent evolution of heat-inducibility during subfunctionalization of the Hsp70 gene family.

    Science.gov (United States)

    Krenek, Sascha; Schlegel, Martin; Berendonk, Thomas U

    2013-02-21

    hsp70s unveiled a corresponding expression pattern, which supports a functionally conserved evolution of the Hsp70 gene family in Paramecium. Our analyses suggest an independent evolution of the heat-inducible cytosol-type hsp70s in Paramecium and in its close relative Tetrahymena, as well as within higher eukaryotes. This result indicates convergent evolution during hsp70 subfunctionalization and implies that heat-inducibility evolved several times during the course of eukaryotic evolution.

  18. Deadly hairs, lethal feathers--convergent evolution of poisonous integument in mammals and birds.

    Science.gov (United States)

    Plikus, Maksim V; Astrowski, Aliaksandr A

    2014-07-01

    Hairs and feathers are textbook examples of the convergent evolution of the follicular appendage structure between mammals and birds. While broadly recognized for their convergent thermoregulatory, camouflage and sexual display functions, hairs and feathers are rarely thought of as deadly defence tools. Several recent studies, however, show that in some species of mammals and birds, the integument can, in fact, be a de facto lethal weapon. One mammalian example is provided by African crested rats, which seek for and chew on the bark of plants containing the highly potent toxin, ouabain. These rats then coat their fur with ouabain-containing saliva. For efficient toxin retention, the rodents have evolved highly specialized fenestrated and mostly hollow hair shafts that soak up liquids, which essentially function as wicks. On the avian side of the vertebrate integumental variety spectrum, several species of birds of New Guinea have evolved resistance to highly potent batrachotoxins, which they acquire from their insect diet. While the mechanism of bird toxicity remains obscure, in a recently published issue of the journal, Dumbacher and Menon explore the intriguing idea that to achieve efficient storage of batrachotoxins in their skin, some birds exploit the basic permeability barrier function of their epidermis. Batrachotoxins become preferentially sequestered in their epidermis and are then transferred to feathers, likely through the exploitation of specialized avian lipid-storing multigranular body organelles. Here, we discuss wider implications of this intriguing concept. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. Convergent evolution and parallelism in plant domestication revealed by an expanding archaeological record.

    Science.gov (United States)

    Fuller, Dorian Q; Denham, Tim; Arroyo-Kalin, Manuel; Lucas, Leilani; Stevens, Chris J; Qin, Ling; Allaby, Robin G; Purugganan, Michael D

    2014-04-29

    Recent increases in archaeobotanical evidence offer insights into the processes of plant domestication and agricultural origins, which evolved in parallel in several world regions. Many different crop species underwent convergent evolution and acquired domestication syndrome traits. For a growing number of seed crop species, these traits can be quantified by proxy from archaeological evidence, providing measures of the rates of change during domestication. Among domestication traits, nonshattering cereal ears evolved more quickly in general than seed size. Nevertheless, most domestication traits show similarly slow rates of phenotypic change over several centuries to millennia, and these rates were similar across different regions of origin. Crops reproduced vegetatively, including tubers and many fruit trees, are less easily documented in terms of morphological domestication, but multiple lines of evidence outline some patterns in the development of vegecultural systems across the New World and Old World tropics. Pathways to plant domestication can also be compared in terms of the cultural and economic factors occurring at the start of the process. Whereas agricultural societies have tended to converge on higher population densities and sedentism, in some instances cultivation began among sedentary hunter-gatherers whereas more often it was initiated by mobile societies of hunter-gatherers or herder-gatherers.

  20. An insight into the molecular basis for convergent evolution in fish antifreeze Proteins.

    Science.gov (United States)

    Nath, Abhigyan; Chaube, Radha; Subbiah, Karthikeyan

    2013-08-01

    Antifreeze proteins (AFPs) prevent the growth of ice-crystals in order to enable certain organisms to survive under sub-zero temperature surroundings. These AFPs have evolved from different types of proteins without having any significant structural and sequence similarities among them. However, all the AFPs perform the same function of anti-freeze activity and are a classical example of convergent evolution. We have analyzed fish AFPs at the sequence level, the residue level and the physicochemical property group composition to discover molecular basis for this convergent evolution. Our study on amino acid distribution does not reveal any distinctive feature among AFPs, but comparative study of the AFPs with their close non-AFP homologs based on the physicochemical property group residues revealed some useful information. In particular (a) there is a similar pattern of avoidance and preference of amino acids in Fish AFP subtypes II, III and IV-Aromatic residues are avoided whereas small residues are preferred, (b) like other psychrophilic proteins, AFPs have a similar pattern of preference/avoidance for most of the residues except for Ile, Leu and Arg, and (c) most of the computed amino acids in preferred list are the key functional residues as obtained in previous predicted model of Doxey et al. For the first time this study revealed common patterns of avoidance/preference in fish AFP subtypes II, III and IV. These avoidance/preference lists can further facilitate the identification of key functional residues and can shed more light into the mechanism of antifreeze function. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Testing Convergent Evolution in Auditory Processing Genes between Echolocating Mammals and the Aye-Aye, a Percussive-Foraging Primate.

    Science.gov (United States)

    Bankoff, Richard J; Jerjos, Michael; Hohman, Baily; Lauterbur, M Elise; Kistler, Logan; Perry, George H

    2017-07-01

    Several taxonomically distinct mammalian groups-certain microbats and cetaceans (e.g., dolphins)-share both morphological adaptations related to echolocation behavior and strong signatures of convergent evolution at the amino acid level across seven genes related to auditory processing. Aye-ayes (Daubentonia madagascariensis) are nocturnal lemurs with a specialized auditory processing system. Aye-ayes tap rapidly along the surfaces of trees, listening to reverberations to identify the mines of wood-boring insect larvae; this behavior has been hypothesized to functionally mimic echolocation. Here we investigated whether there are signals of convergence in auditory processing genes between aye-ayes and known mammalian echolocators. We developed a computational pipeline (Basic Exon Assembly Tool) that produces consensus sequences for regions of interest from shotgun genomic sequencing data for nonmodel organisms without requiring de novo genome assembly. We reconstructed complete coding region sequences for the seven convergent echolocating bat-dolphin genes for aye-ayes and another lemur. We compared sequences from these two lemurs in a phylogenetic framework with those of bat and dolphin echolocators and appropriate nonecholocating outgroups. Our analysis reaffirms the existence of amino acid convergence at these loci among echolocating bats and dolphins; some methods also detected signals of convergence between echolocating bats and both mice and elephants. However, we observed no significant signal of amino acid convergence between aye-ayes and echolocating bats and dolphins, suggesting that aye-aye tap-foraging auditory adaptations represent distinct evolutionary innovations. These results are also consistent with a developing consensus that convergent behavioral ecology does not reliably predict convergent molecular evolution. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  2. Convergent evolution of modularity in metabolic networks through different community structures.

    Science.gov (United States)

    Zhou, Wanding; Nakhleh, Luay

    2012-09-14

    It has been reported that the modularity of metabolic networks of bacteria is closely related to the variability of their living habitats. However, given the dependency of the modularity score on the community structure, it remains unknown whether organisms achieve certain modularity via similar or different community structures. In this work, we studied the relationship between similarities in modularity scores and similarities in community structures of the metabolic networks of 1021 species. Both similarities are then compared against the genetic distances. We revisited the association between modularity and variability of the microbial living environments and extended the analysis to other aspects of their life style such as temperature and oxygen requirements. We also tested both topological and biological intuition of the community structures identified and investigated the extent of their conservation with respect to the taxonomy. We find that similar modularities are realized by different community structures. We find that such convergent evolution of modularity is closely associated with the number of (distinct) enzymes in the organism's metabolome, a consequence of different life styles of the species. We find that the order of modularity is the same as the order of the number of the enzymes under the classification based on the temperature preference but not on the oxygen requirement. Besides, inspection of modularity-based communities reveals that these communities are graph-theoretically meaningful yet not reflective of specific biological functions. From an evolutionary perspective, we find that the community structures are conserved only at the level of kingdoms. Our results call for more investigation into the interplay between evolution and modularity: how evolution shapes modularity, and how modularity affects evolution (mainly in terms of fitness and evolvability). Further, our results call for exploring new measures of modularity and network

  3. Convergent evolution of modularity in metabolic networks through different community structures

    Directory of Open Access Journals (Sweden)

    Zhou Wanding

    2012-09-01

    Full Text Available Abstract Background It has been reported that the modularity of metabolic networks of bacteria is closely related to the variability of their living habitats. However, given the dependency of the modularity score on the community structure, it remains unknown whether organisms achieve certain modularity via similar or different community structures. Results In this work, we studied the relationship between similarities in modularity scores and similarities in community structures of the metabolic networks of 1021 species. Both similarities are then compared against the genetic distances. We revisited the association between modularity and variability of the microbial living environments and extended the analysis to other aspects of their life style such as temperature and oxygen requirements. We also tested both topological and biological intuition of the community structures identified and investigated the extent of their conservation with respect to the taxomony. Conclusions We find that similar modularities are realized by different community structures. We find that such convergent evolution of modularity is closely associated with the number of (distinct enzymes in the organism’s metabolome, a consequence of different life styles of the species. We find that the order of modularity is the same as the order of the number of the enzymes under the classification based on the temperature preference but not on the oxygen requirement. Besides, inspection of modularity-based communities reveals that these communities are graph-theoretically meaningful yet not reflective of specific biological functions. From an evolutionary perspective, we find that the community structures are conserved only at the level of kingdoms. Our results call for more investigation into the interplay between evolution and modularity: how evolution shapes modularity, and how modularity affects evolution (mainly in terms of fitness and evolvability. Further, our results

  4. Ontogenetic convergence and evolution of foot morphology in European cave salamanders (Family: Plethodontidae

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    Nistri Annamaria

    2010-07-01

    Full Text Available Abstract Background A major goal in evolutionary biology is to understand the evolution of phenotypic diversity. Both natural and sexual selection play a large role in generating phenotypic adaptations, with biomechanical requirements and developmental mechanisms mediating patterns of phenotypic evolution. For many traits, the relative importance of selective and developmental components remains understudied. Results We investigated ontogenetic trajectories of foot morphology in the eight species of European plethodontid cave salamander to test the hypothesis that adult foot morphology was adapted for climbing. Using geometric morphometrics and other approaches, we found that developmental patterns in five species displayed little morphological change during growth (isometry, where the extensive interdigital webbing in adults was best explained as the retention of the juvenile morphological state. By contrast, three species exhibited significant allometry, with an increase in interdigital webbing during growth. Phylogenetic analyses revealed that multiple evolutionary transitions between isometry and allometry of foot webbing have occurred in this lineage. Allometric parameters of foot growth were most similar to those of a tropical species previously shown to be adapted for climbing. Finally, interspecific variation in adult foot morphology was significantly reduced as compared to variation among juveniles, indicating that ontogenetic convergence had resulted in a common adult foot morphology across species. Conclusions The results presented here provide evidence of a complex history of phenotypic evolution in this clade. The common adult phenotype exhibited among species reveals that selection plays an important part in generating patterns of foot diversity in the group. However, developmental trajectories arriving at this common morphology are distinct; with some species displaying developmental stasis (isometry, while others show an increase

  5. Thoughts on the diversity of convergent evolution of bioluminescence on earth

    Science.gov (United States)

    Waldenmaier, Hans E.; Oliveira, Anderson G.; Stevani, Cassius V.

    2012-10-01

    The widespread independent evolution of analogous bioluminescent systems is one of the most impressive and diverse examples of convergent evolution on earth. There are roughly 30 extant bioluminescent systems that have evolved independently on Earth, with each system likely having unique enzymes responsible for catalysing the bioluminescent reaction. Bioluminescence is a chemical reaction involving a luciferin molecule and a luciferase or photoprotein that results in the emission of light. Some independent systems utilize the same luciferin, such as the use of tetrapyrrolic compounds by krill and dinoflagellates, and the wide use of coelenterazine by marine organisms, while the enzymes involved are unique. One common thread among all the different bioluminescent systems is the requirement of molecular oxygen. Bioluminescence is found in most forms of life, especially marine organisms. Bioluminescence in known to benefit the organism by: attraction, repulsion, communication, camouflage, and illumination. The marine ecosystem is significantly affected by bioluminescence, the only light found in the pelagic zone and below is from bioluminescent organisms. Transgenic bioluminescent organisms have revolutionized molecular research, medicine and the biotechnology industry. The use of bioluminescence in studying molecular pathways and disease allows for non-invasive and real-time analysis. Bioluminescence-based assays have been developed for several analytes by coupling luminescence to many enzyme-catalysed reactions.

  6. Convergent evolution in European and Rroma populations reveals pressure exerted by plague on Toll-like receptors

    NARCIS (Netherlands)

    Laayouni, H.; Oosting, M.; Luisi, P.; Ioana, M.; Alonso, S.; Ricano-Ponce, I.; Trynka, G.; Zhernakova, A.; Plantinga, T.S.; Cheng, S.C.; Meer, J.W. van der; Popp, R.; Sood, A.; Thelma, B.K.; Wijmenga, C.; Joosten, L.A.; Bertranpetit, J.; Netea, M.G.

    2014-01-01

    Recent historical periods in Europe have been characterized by severe epidemic events such as plague, smallpox, or influenza that shaped the immune system of modern populations. This study aims to identify signals of convergent evolution of the immune system, based on the peculiar demographic

  7. Convergent evolution of chemical defense in poison frogs and arthropod prey between Madagascar and the Neotropics.

    Science.gov (United States)

    Clark, Valerie C; Raxworthy, Christopher J; Rakotomalala, Valérie; Sierwald, Petra; Fisher, Brian L

    2005-08-16

    With few exceptions, aposematically colored poison frogs sequester defensive alkaloids, unchanged, from dietary arthropods. In the Neotropics, myrmicine and formicine ants and the siphonotid millipede Rhinotus purpureus are dietary sources for alkaloids in dendrobatid poison frogs, yet the arthropod sources for Mantella poison frogs in Madagascar remained unknown. We report GC-MS analyses of extracts of arthropods and microsympatric Malagasy poison frogs (Mantella) collected from Ranomafana, Madagascar. Arthropod sources for 11 "poison frog" alkaloids were discovered, 7 of which were also detected in microsympatric Mantella. These arthropod sources include three endemic Malagasy ants, Tetramorium electrum, Anochetus grandidieri, and Paratrechina amblyops (subfamilies Myrmicinae, Ponerinae, and Formicinae, respectively), and the pantropical tramp millipede R. purpureus. Two of these ant species, A. grandidieri and T. electrum, were also found in Mantella stomachs, and ants represented the dominant prey type (67.3% of 609 identified stomach arthropods). To our knowledge, detection of 5,8-disubstituted (ds) indolizidine iso-217B in T. electrum represents the first izidine having a branch point in its carbon skeleton to be identified from ants, and detection of 3,5-ds pyrrolizidine 251O in A. grandidieri represents the first ponerine ant proposed as a dietary source of poison frog alkaloids. Endemic Malagasy ants with defensive alkaloids (with the exception of Paratrechina) are not closely related to any Neotropical species sharing similar chemical defenses. Our results suggest convergent evolution for the acquisition of defensive alkaloids in these dietary ants, which may have been the critical prerequisite for subsequent convergence in poison frogs between Madagascar and the Neotropics.

  8. A new horned dinosaur reveals convergent evolution in cranial ornamentation in Ceratopsidae.

    Science.gov (United States)

    Brown, Caleb M; Henderson, Donald M

    2015-06-15

    Ceratopsid (horned) dinosaurs are an iconic group of large-bodied, quadrupedal, herbivorous dinosaurs that evolved in the Late Cretaceous and were largely restricted to western North America [1-5]. Ceratopsids are easily recognized by their cranial ornamentation in the form of nasal and postorbital horns and frill (capped by epiossifications); these structures show high morphological disparity and also represent the largest cranial display structures known to have evolved [2, 4]. Despite their restricted occurrence in time and space, this group has one of the best fossil records within Dinosauria, showing a rapid diversification in horn and frill morphology [1]. Here a new genus and species of chasmosaurine ceratopsid is described based on a nearly complete and three-dimensionally preserved cranium recovered from the uppermost St. Mary River Formation (Maastrichtian) of southwestern Alberta. Regaliceratops peterhewsi gen. et sp. nov. exhibits many unique characters of the frill and is characterized by a large nasal horncore, small postorbital horncores, and massive parietal epiossifications. Cranial morphology, particularly the epiossifications, suggests close affinity with the late Campanian/early Maastrichian taxon Anchiceratops, as well as with the late Maastrichtian taxon Triceratops. A median epiparietal necessitates a reassessment of epiossification homology and results in a more resolved phylogeny. Most surprisingly, Regaliceratops exhibits a suite of cranial ornamentations that are superficially similar to Campanian centrosaurines, indicating both exploration of novel display morphospace in Chasmosaurinae, especially Maastrichtian forms, and convergent evolution in horn morphology with the recently extinct Centrosaurinae. This marks the first time that evolutionary convergence in horn-like display structures has been demonstrated between dinosaur clades, similar to those seen in fossil and extant mammals [6]. Copyright © 2015 Elsevier Ltd. All rights

  9. Convergent evolution of highly reduced fruiting bodies in Pezizomycotina suggests key adaptations to the bee habitat.

    Science.gov (United States)

    Wynns, Anja Amtoft

    2015-07-21

    cyst are both shown to have evolved convergently within the bee habitat. The convergent evolution of these unusual ascocarps is hypothesized to be adaptive for bee-mediated dispersal. Elucidating the dispersal strategies of these fungal symbionts contributes to our understanding of their interaction with bees and provides insight into the factors which potentially drive the evolution of reduced ascocarps in Pezizomycotina.

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

    Science.gov (United States)

    Zelditch, Miriam Leah; Ye, Ji; Mitchell, Jonathan S; Swiderski, Donald L

    2017-03-01

    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. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

  11. Molecular systematics of eastern North American Phalangodidae (Arachnida: Opiliones: Laniatores), demonstrating convergent morphological evolution in caves.

    Science.gov (United States)

    Hedin, Marshal; Thomas, Steven M

    2010-01-01

    The phalangodid harvestmen (Opiliones: Laniatores) fauna of the southeastern United States has remained obscure since original descriptions of many genera and species over 60 years ago. The obscurity of this interesting group is pervasive, with uncertainty regarding basic systematic information such as generic limits, species limits, and geographic distributions. This situation is unfortunate, as the fauna includes several cave-obligate forms of interest from both conservation and evolutionary perspectives, and the group likely exhibits interesting biogeographic patterns because of their low dispersal ability. Here, we use DNA sequence data from two genes to reconstruct phylogenetic relationships of southeastern phalangodid taxa, for a sample of all described genera from the region. Our results demonstrate that the southeastern fauna is likely monophyletic, and is most-closely related to western North American phalangodids with a similar penis morphology. Within the southeastern clade, trends in the evolution of penis morphology correspond broadly to molecular phylogenetic patterns, although penis evolution is overall relatively conservative in the group. Biogeographically, it appears that western taxa in the southeast (i.e., from west of the Appalachian Valley) are early diverging, with later diversification in the montane southern Blue Ridge, and subsequent diversification back towards the west. This W>E>W pattern has been observed in other groups from the southeast. The multiple cave-modified species in the region are genetically divergent and appear phylogenetically isolated; explicit topological hypothesis testing suggests that troglomorphism has evolved convergently in at least three independent lineages. The total number of species in the region remains uncertain-mitochondrial COI data reveal many highly divergent, geographically coherent groups that might represent undescribed species, but these divergent mitochondrial lineages do not always exhibit

  12. Convergent evolution of anthropoid-like adaptations in Eocene adapiform primates.

    Science.gov (United States)

    Seiffert, Erik R; Perry, Jonathan M G; Simons, Elwyn L; Boyer, Doug M

    2009-10-22

    Adapiform or 'adapoid' primates first appear in the fossil record in the earliest Eocene epoch ( approximately 55 million years (Myr) ago), and were common components of Palaeogene primate communities in Europe, Asia and North America. Adapiforms are commonly referred to as the 'lemur-like' primates of the Eocene epoch, and recent phylogenetic analyses have placed adapiforms as stem members of Strepsirrhini, a primate suborder whose crown clade includes lemurs, lorises and galagos. An alternative view is that adapiforms are stem anthropoids. This debate has recently been rekindled by the description of a largely complete skeleton of the adapiform Darwinius, from the middle Eocene of Europe, which has been widely publicised as an important 'link' in the early evolution of Anthropoidea. Here we describe the complete dentition and jaw of a large-bodied adapiform (Afradapis gen. nov.) from the earliest late Eocene of Egypt ( approximately 37 Myr ago) that exhibits a striking series of derived dental and gnathic features that also occur in younger anthropoid primates-notably the earliest catarrhine ancestors of Old World monkeys and apes. Phylogenetic analysis of 360 morphological features scored across 117 living and extinct primates (including all candidate stem anthropoids) does not place adapiforms as haplorhines (that is, members of a Tarsius-Anthropoidea clade) or as stem anthropoids, but rather as sister taxa of crown Strepsirrhini; Afradapis and Darwinius are placed in a geographically widespread clade of caenopithecine adapiforms that left no known descendants. The specialized morphological features that these adapiforms share with anthropoids are therefore most parsimoniously interpreted as evolutionary convergences. As the largest non-anthropoid primate ever documented in Afro-Arabia, Afradapis nevertheless provides surprising new evidence for prosimian diversity in the Eocene of Africa, and raises the possibility that ecological competition between

  13. Extreme environments as potential drivers of convergent evolution by exaptation: the Atacama Desert Coastal Range case.

    Directory of Open Access Journals (Sweden)

    Armando eAzua-Bustos

    2012-12-01

    Full Text Available We have recently discovered a variety of unrelated phototrophic microorganisms (two microalgae and one cyanobacteria in specialized terrestrial habitats at The Coastal Range of the Atacama Desert. Interestingly, morphological and molecular evidence suggest that these three species are all recent colonists that came from aquatic habitats. The first case is Cyanidiales inhabiting coastal caves. Cyanidiales are microalgae that are commonly found in warm acid springs, but have also been recently discovered as cave flora in Italy. The case is Dunaliella biofilms colonizing spider webs in coastal caves; Dunaliella are microalgae typically found in hypersaline habitats. The third case is Chroococcidiopsis, a genus of Cyanobacteria commonly found in deserts around the world that has also been described in warm springs. Thus, we show that the traits found in the closest ancestors of the aforementioned species (which inhabited other unrelated extreme environments seem to be now useful for the described species in their current subaerial habitats, and may likely correspond to cases of exaptations. Altogether, the Coastal Range of the Atacama Desert may be considered as a place where key steps on the colonization of land by phototrophic organisms seem to be being repeated by convergent evolution of extant microalgae and Cyanobacteria.

  14. The acacia ants revisited: convergent evolution and biogeographic context in an iconic ant/plant mutualism.

    Science.gov (United States)

    Ward, Philip S; Branstetter, Michael G

    2017-03-15

    Phylogenetic and biogeographic analyses can enhance our understanding of multispecies interactions by placing the origin and evolution of such interactions in a temporal and geographical context. We use a phylogenomic approach-ultraconserved element sequence capture-to investigate the evolutionary history of an iconic multispecies mutualism: Neotropical acacia ants (Pseudomyrmex ferrugineus group) and their associated Vachellia hostplants. In this system, the ants receive shelter and food from the host plant, and they aggressively defend the plant against herbivores and competing plants. We confirm the existence of two separate lineages of obligate acacia ants that convergently occupied Vachellia and evolved plant-protecting behaviour, from timid ancestors inhabiting dead twigs in rainforest. The more diverse of the two clades is inferred to have arisen in the Late Miocene in northern Mesoamerica, and subsequently expanded its range throughout much of Central America. The other lineage is estimated to have originated in southern Mesoamerica about 3 Myr later, apparently piggy-backing on the pre-existing mutualism. Initiation of the Pseudomyrmex/Vachellia interaction involved a shift in the ants from closed to open habitats, into an environment with more intense plant herbivory. Comparative studies of the two lineages of mutualists should provide insight into the essential features binding this mutualism. © 2017 The Author(s).

  15. Experimental evidence for convergent evolution of maternal care heuristics in industrialized and small-scale populations.

    Science.gov (United States)

    Kushnick, Geoff; Hanowell, Ben; Kim, Jun-Hong; Langstieh, Banrida; Magnano, Vittorio; Oláh, Katalin

    2015-06-01

    Maternal care decision rules should evolve responsiveness to factors impinging on the fitness pay-offs of care. Because the caretaking environments common in industrialized and small-scale societies vary in predictable ways, we hypothesize that heuristics guiding maternal behaviour will also differ between these two types of populations. We used a factorial vignette experiment to elicit third-party judgements about likely caretaking decisions of a hypothetical mother and her child when various fitness-relevant factors (maternal age and access to resources, and offspring age, sex and quality) were varied systematically in seven populations-three industrialized and four small-scale. Despite considerable variation in responses, we found that three of five main effects, and the two severity effects, exhibited statistically significant industrialized/ small-scale population differences. All differences could be explained as adaptive solutions to industrialized versus small-scale caretaking environments. Further, we found gradients in the relationship between the population-specific estimates and national-level socio-economic indicators, further implicating important aspects of the variation in industrialized and small-scale caretaking environments in shaping heuristics. Although there is mounting evidence for a genetic component to human maternal behaviour, there is no current evidence for interpopulation variation in candidate genes. We nonetheless suggest that heuristics guiding maternal behaviour in diverse societies emerge via convergent evolution in response to similar selective pressures.

  16. Discovery of lignin in seaweed reveals convergent evolution of cell-wall architecture.

    Science.gov (United States)

    Martone, Patrick T; Estevez, José M; Lu, Fachuang; Ruel, Katia; Denny, Mark W; Somerville, Chris; Ralph, John

    2009-01-27

    Lignified cell walls are widely considered to be key innovations in the evolution of terrestrial plants from aquatic ancestors some 475 million years ago. Lignins, complex aromatic heteropolymers, stiffen and fortify secondary cell walls within xylem tissues, creating a dense matrix that binds cellulose microfibrils and crosslinks other wall components, thereby preventing the collapse of conductive vessels, lending biomechanical support to stems, and allowing plants to adopt an erect-growth habit in air. Although "lignin-like" compounds have been identified in primitive green algae, the presence of true lignins in nonvascular organisms, such as aquatic algae, has not been confirmed. Here, we report the discovery of secondary walls and lignin within cells of the intertidal red alga Calliarthron cheilosporioides. Until now, such developmentally specialized cell walls have been described only in vascular plants. The finding of secondary walls and lignin in red algae raises many questions about the convergent or deeply conserved evolutionary history of these traits, given that red algae and vascular plants probably diverged more than 1 billion years ago.

  17. Convergent adaptation of cellular machineries in the evolution of large body masses and long life spans.

    Science.gov (United States)

    Croco, Eleonora; Marchionni, Silvia; Storci, Gianluca; Bonafè, Massimiliano; Franceschi, Claudio; Stamato, Thomas D; Sell, Christian; Lorenzini, Antonello

    2017-08-01

    In evolutionary terms, life on the planet has taken the form of independently living cells for the majority of time. In comparison, the mammalian radiation is a relatively recent event. The common mammalian ancestor was probably small and short-lived. The "recent" acquisition of an extended longevity and large body mass of some species of mammals present on the earth today suggests the possibility that similar cellular mechanisms have been influenced by the forces of natural selection to create a convergent evolution of longevity. Many cellular mechanisms are potentially relevant for extending longevity; in this assay, we review the literature focusing primarily on two cellular features: (1) the capacity for extensive cellular proliferation of differentiated cells, while maintaining genome stability; and (2) the capacity to detect DNA damage. We have observed that longevity and body mass are both positively linked to these cellular mechanisms and then used statistical tools to evaluate their relative importance. Our analysis suggest that the capacity for extensive cellular proliferation while maintaining sufficient genome stability, correlates to species body mass while the capacity to correctly identify the presence of DNA damage seems more an attribute of long-lived species. Finally, our data are in support of the idea that a slower development, allowing for better DNA damage detection and handling, should associate with longer life span.

  18. Trema and parasponia hemoglobins reveal convergent evolution of oxygen transport in plants.

    Science.gov (United States)

    Sturms, Ryan; Kakar, Smita; Trent, James; Hargrove, Mark S

    2010-05-18

    All plants contain hemoglobins that fall into distinct phylogenetic classes. The subset of plants that carry out symbiotic nitrogen fixation expresses hemoglobins that scavenge and transport oxygen to bacterial symbiotes within root nodules. These "symbiotic" oxygen transport hemoglobins are distinct in structure and function from the nonoxygen transport ("nonsymbiotic") Hbs found in all plants. Hemoglobins found in two closely related plants present a paradox concerning hemoglobin structure and function. Parasponia andersonii is a nitrogen-fixing plant that expresses a symbiotic hemoglobin (ParaHb) characteristic of oxygen transport hemoglobins in having a pentacoordinate ferrous heme iron, moderate oxygen affinity, and a relatively rapid oxygen dissociation rate constant. A close relative that does not fix nitrogen, Trema tomentosa, expresses hemoglobin (TremaHb) sharing 93% amino acid identity to ParaHb, but its phylogeny predicts a typical nonsymbiotic hemoglobin with a hexacoordinate heme iron, high oxygen affinity, and slow oxygen dissociation rate constant. Here we characterize heme coordination and oxygen binding in TremaHb and ParaHb to investigate whether or not two hemoglobins with such high sequence similarity are actually so different in functional behavior. Our results indicate that the two proteins resemble nonsymbiotic hemoglobins in the ferric oxidation state and symbiotic hemoglobins in the ferrous oxidation state. They differ from each other only in oxygen affinity and oxygen dissociation rate constants, two factors key to their different functions. These results demonstrate distinct mechanisms for convergent evolution of oxygen transport in different phylogenetic classes of plant hemoglobins.

  19. Convergent Evolution of Hemoglobin Function in High-Altitude Andean Waterfowl Involves Limited Parallelism at the Molecular Sequence Level.

    Science.gov (United States)

    Natarajan, Chandrasekhar; Projecto-Garcia, Joana; Moriyama, Hideaki; Weber, Roy E; Muñoz-Fuentes, Violeta; Green, Andy J; Kopuchian, Cecilia; Tubaro, Pablo L; Alza, Luis; Bulgarella, Mariana; Smith, Matthew M; Wilson, Robert E; Fago, Angela; McCracken, Kevin G; Storz, Jay F

    2015-12-01

    A fundamental question in evolutionary genetics concerns the extent to which adaptive phenotypic convergence is attributable to convergent or parallel changes at the molecular sequence level. Here we report a comparative analysis of hemoglobin (Hb) function in eight phylogenetically replicated pairs of high- and low-altitude waterfowl taxa to test for convergence in the oxygenation properties of Hb, and to assess the extent to which convergence in biochemical phenotype is attributable to repeated amino acid replacements. Functional experiments on native Hb variants and protein engineering experiments based on site-directed mutagenesis revealed the phenotypic effects of specific amino acid replacements that were responsible for convergent increases in Hb-O2 affinity in multiple high-altitude taxa. In six of the eight taxon pairs, high-altitude taxa evolved derived increases in Hb-O2 affinity that were caused by a combination of unique replacements, parallel replacements (involving identical-by-state variants with independent mutational origins in different lineages), and collateral replacements (involving shared, identical-by-descent variants derived via introgressive hybridization). In genome scans of nucleotide differentiation involving high- and low-altitude populations of three separate species, function-altering amino acid polymorphisms in the globin genes emerged as highly significant outliers, providing independent evidence for adaptive divergence in Hb function. The experimental results demonstrate that convergent changes in protein function can occur through multiple historical paths, and can involve multiple possible mutations. Most cases of convergence in Hb function did not involve parallel substitutions and most parallel substitutions did not affect Hb-O2 affinity, indicating that the repeatability of phenotypic evolution does not require parallelism at the molecular level.

  20. "Pseudo-Beijing": evidence for convergent evolution in the direct repeat region of Mycobacterium tuberculosis.

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    Lukas Fenner

    Full Text Available Mycobacterium tuberculosis has a global population structure consisting of six main phylogenetic lineages associated with specific geographic regions and human populations. One particular M. tuberculosis genotype known as "Beijing" has repeatedly been associated with drug resistance and has been emerging in some parts of the world. "Beijing" strains are traditionally defined based on a characteristic spoligotyping pattern. We used three alternative genotyping techniques to revisit the phylogenetic classification of M. tuberculosis complex (MTBC strains exhibiting the typical "Beijing" spoligotyping pattern.MTBC strains were obtained from an ongoing molecular epidemiological study in Switzerland and Nepal. MTBC genotyping was performed based on SNPs, genomic deletions, and 24-loci MIRU-VNTR. We identified three MTBC strains from patients originating from Tibet, Portugal and Nepal which exhibited a spoligotyping patterns identical to the classical Beijing signature. However, based on three alternative molecular markers, these strains were assigned to Lineage 3 (also known as Delhi/CAS rather than to Lineage 2 (also known as East-Asian lineage. Sequencing of the RD207 in one of these strains showed that the deletion responsible for this "Pseudo-Beijing" spoligotype was about 1,000 base pairs smaller than the usual deletion of RD207 in classical "Beijing" strains, which is consistent with an evolutionarily independent deletion event in the direct repeat (DR region of MTBC.We provide an example of convergent evolution in the DR locus of MTBC, and highlight the limitation of using spoligotypes for strain classification. Our results indicate that a proportion of "Beijing" strains may have been misclassified in the past. Markers that are more phylogenetically robust should be used when exploring strain-specific differences in experimental or clinical phenotypes.

  1. An Eocene orthocone from Antarctica shows convergent evolution of internally shelled cephalopods.

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    Larisa A Doguzhaeva

    Full Text Available The Subclass Coleoidea (Class Cephalopoda accommodates the diverse present-day internally shelled cephalopod mollusks (Spirula, Sepia and octopuses, squids, Vampyroteuthis and also extinct internally shelled cephalopods. Recent Spirula represents a unique coleoid retaining shell structures, a narrow marginal siphuncle and globular protoconch that signify the ancestry of the subclass Coleoidea from the Paleozoic subclass Bactritoidea. This hypothesis has been recently supported by newly recorded diverse bactritoid-like coleoids from the Carboniferous of the USA, but prior to this study no fossil cephalopod indicative of an endochochleate branch with an origin independent from subclass Bactritoidea has been reported.Two orthoconic conchs were recovered from the Early Eocene of Seymour Island at the tip of the Antarctic Peninsula, Antarctica. They have loosely mineralized organic-rich chitin-compatible microlaminated shell walls and broadly expanded central siphuncles. The morphological, ultrustructural and chemical data were determined and characterized through comparisons with extant and extinct taxa using Scanning Electron Microscopy/Energy Dispersive Spectrometry (SEM/EDS.Our study presents the first evidence for an evolutionary lineage of internally shelled cephalopods with independent origin from Bactritoidea/Coleoidea, indicating convergent evolution with the subclass Coleoidea. A new subclass Paracoleoidea Doguzhaeva n. subcl. is established for accommodation of orthoconic cephalopods with the internal shell associated with a broadly expanded central siphuncle. Antarcticerida Doguzhaeva n. ord., Antarcticeratidae Doguzhaeva n. fam., Antarcticeras nordenskjoeldi Doguzhaeva n. gen., n. sp. are described within the subclass Paracoleoidea. The analysis of organic-rich shell preservation of A. nordenskjoeldi by use of SEM/EDS techniques revealed fossilization of hyposeptal cameral soft tissues. This suggests that a depositional environment

  2. An Eocene orthocone from Antarctica shows convergent evolution of internally shelled cephalopods.

    Science.gov (United States)

    Doguzhaeva, Larisa A; Bengtson, Stefan; Reguero, Marcelo A; Mörs, Thomas

    2017-01-01

    The Subclass Coleoidea (Class Cephalopoda) accommodates the diverse present-day internally shelled cephalopod mollusks (Spirula, Sepia and octopuses, squids, Vampyroteuthis) and also extinct internally shelled cephalopods. Recent Spirula represents a unique coleoid retaining shell structures, a narrow marginal siphuncle and globular protoconch that signify the ancestry of the subclass Coleoidea from the Paleozoic subclass Bactritoidea. This hypothesis has been recently supported by newly recorded diverse bactritoid-like coleoids from the Carboniferous of the USA, but prior to this study no fossil cephalopod indicative of an endochochleate branch with an origin independent from subclass Bactritoidea has been reported. Two orthoconic conchs were recovered from the Early Eocene of Seymour Island at the tip of the Antarctic Peninsula, Antarctica. They have loosely mineralized organic-rich chitin-compatible microlaminated shell walls and broadly expanded central siphuncles. The morphological, ultrustructural and chemical data were determined and characterized through comparisons with extant and extinct taxa using Scanning Electron Microscopy/Energy Dispersive Spectrometry (SEM/EDS). Our study presents the first evidence for an evolutionary lineage of internally shelled cephalopods with independent origin from Bactritoidea/Coleoidea, indicating convergent evolution with the subclass Coleoidea. A new subclass Paracoleoidea Doguzhaeva n. subcl. is established for accommodation of orthoconic cephalopods with the internal shell associated with a broadly expanded central siphuncle. Antarcticerida Doguzhaeva n. ord., Antarcticeratidae Doguzhaeva n. fam., Antarcticeras nordenskjoeldi Doguzhaeva n. gen., n. sp. are described within the subclass Paracoleoidea. The analysis of organic-rich shell preservation of A. nordenskjoeldi by use of SEM/EDS techniques revealed fossilization of hyposeptal cameral soft tissues. This suggests that a depositional environment favoring soft

  3. Molecular Evidence for Convergence and Parallelism in Evolution of Complex Brains of Cephalopod Molluscs: Insights from Visual Systems.

    Science.gov (United States)

    Yoshida, M A; Ogura, A; Ikeo, K; Shigeno, S; Moritaki, T; Winters, G C; Kohn, A B; Moroz, L L

    2015-12-01

    Coleoid cephalopods show remarkable evolutionary convergence with vertebrates in their neural organization, including (1) eyes and visual system with optic lobes, (2) specialized parts of the brain controlling learning and memory, such as vertical lobes, and (3) unique vasculature supporting such complexity of the central nervous system. We performed deep sequencing of eye transcriptomes of pygmy squids (Idiosepius paradoxus) and chambered nautiluses (Nautilus pompilius) to decipher the molecular basis of convergent evolution in cephalopods. RNA-seq was complemented by in situ hybridization to localize the expression of selected genes. We found three types of genomic innovations in the evolution of complex brains: (1) recruitment of novel genes into morphogenetic pathways, (2) recombination of various coding and regulatory regions of different genes, often called "evolutionary tinkering" or "co-option", and (3) duplication and divergence of genes. Massive recruitment of novel genes occurred in the evolution of the "camera" eye from nautilus' "pinhole" eye. We also showed that the type-2 co-option of transcription factors played important roles in the evolution of the lens and visual neurons. In summary, the cephalopod convergent morphological evolution of the camera eyes was driven by a mosaic of all types of gene recruitments. In addition, our analysis revealed unexpected variations of squids' opsins, retinochromes, and arrestins, providing more detailed information, valuable for further research on intra-ocular and extra-ocular photoreception of the cephalopods. © The Author 2015. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

  4. Convergent evolution of marine mammals is associated with distinct substitutions in common genes.

    Science.gov (United States)

    Zhou, Xuming; Seim, Inge; Gladyshev, Vadim N

    2015-11-09

    Phenotypic convergence is thought to be driven by parallel substitutions coupled with natural selection at the sequence level. Multiple independent evolutionary transitions of mammals to an aquatic environment offer an opportunity to test this thesis. Here, whole genome alignment of coding sequences identified widespread parallel amino acid substitutions in marine mammals; however, the majority of these changes were not unique to these animals. Conversely, we report that candidate aquatic adaptation genes, identified by signatures of likelihood convergence and/or elevated ratio of nonsynonymous to synonymous nucleotide substitution rate, are characterized by very few parallel substitutions and exhibit distinct sequence changes in each group. Moreover, no significant positive correlation was found between likelihood convergence and positive selection in all three marine lineages. These results suggest that convergence in protein coding genes associated with aquatic lifestyle is mainly characterized by independent substitutions and relaxed negative selection.

  5. CONVERGENT EVOLUTION OF COURTSHIP SONGS AMONG CRYPTIC SPECIES OF THE CARNEA GROUP OF GREEN LACEWINGS (NEUROPTERA: CHRYSOPIDAE: CHRYSOPERLA).

    Science.gov (United States)

    Henry, Charles S; Wells, Marta Lucía Martínez; Simon, Chris M

    1999-08-01

    Although traits of related species are likely to be similar due to common ancestry, mating signals are an exception. In singing insects, for example, song similarity has been documented only for allopatric or allochronic species pairs, and even then, not often. Where song similarity does occur, it has been logically attributed to the inheritance of ancestral traits rather than convergence. It is quite common for related, sympatric insect species to differ dramatically in calling song, which is predicted by evolutionary theory to maximize intraspecific mating success. Given that there are a limited number of ways to make sounds on anatomically similar organs and given that there would be no selective pressure for songs to differ in widely separated geographic areas, convergence in songs among related species living on different continents might be expected. Here we present the first well-documented case of such convergence, in a group of sibling, cryptic species characterized by substrate-borne vibrational mating songs. In this example from green lacewings of the carnea group of the genus Chrysoperla, a variety of statistical tests shows that one species in North America and another in Asia possess songs that are strikingly similar to each other. DNA data demonstrate that the species involved belong to divergent speciose lineages, and behavioral data demonstrate that the convergent songs are readily accepted by members of both species. © 1999 The Society for the Study of Evolution.

  6. Evidence for a convergent slowdown in primate molecular rates and its implications for the timing of early primate evolution.

    Science.gov (United States)

    Steiper, Michael E; Seiffert, Erik R

    2012-04-17

    A long-standing problem in primate evolution is the discord between paleontological and molecular clock estimates for the time of crown primate origins: the earliest crown primate fossils are ~56 million y (Ma) old, whereas molecular estimates for the haplorhine-strepsirrhine split are often deep in the Late Cretaceous. One explanation for this phenomenon is that crown primates existed in the Cretaceous but that their fossil remains have not yet been found. Here we provide strong evidence that this discordance is better-explained by a convergent molecular rate slowdown in early primate evolution. We show that molecular rates in primates are strongly and inversely related to three life-history correlates: body size (BS), absolute endocranial volume (EV), and relative endocranial volume (REV). Critically, these traits can be reconstructed from fossils, allowing molecular rates to be predicted for extinct primates. To this end, we modeled the evolutionary history of BS, EV, and REV using data from both extinct and extant primates. We show that the primate last common ancestor had a very small BS, EV, and REV. There has been a subsequent convergent increase in BS, EV, and REV, indicating that there has also been a convergent molecular rate slowdown over primate evolution. We generated a unique timescale for primates by predicting molecular rates from the reconstructed phenotypic values for a large phylogeny of living and extinct primates. This analysis suggests that crown primates originated close to the K-Pg boundary and possibly in the Paleocene, largely reconciling the molecular and fossil timescales of primate evolution.

  7. Parallel and convergent evolution of the dim-light vision gene RH1 in bats (Order: Chiroptera.

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    Yong-Yi Shen

    Full Text Available Rhodopsin, encoded by the gene Rhodopsin (RH1, is extremely sensitive to light, and is responsible for dim-light vision. Bats are nocturnal mammals that inhabit poor light environments. Megabats (Old-World fruit bats generally have well-developed eyes, while microbats (insectivorous bats have developed echolocation and in general their eyes were degraded, however, dramatic differences in the eyes, and their reliance on vision, exist in this group. In this study, we examined the rod opsin gene (RH1, and compared its evolution to that of two cone opsin genes (SWS1 and M/LWS. While phylogenetic reconstruction with the cone opsin genes SWS1 and M/LWS generated a species tree in accord with expectations, the RH1 gene tree united Pteropodidae (Old-World fruit bats and Yangochiroptera, with very high bootstrap values, suggesting the possibility of convergent evolution. The hypothesis of convergent evolution was further supported when nonsynonymous sites or amino acid sequences were used to construct phylogenies. Reconstructed RH1 sequences at internal nodes of the bat species phylogeny showed that: (1 Old-World fruit bats share an amino acid change (S270G with the tomb bat; (2 Miniopterus share two amino acid changes (V104I, M183L with Rhinolophoidea; (3 the amino acid replacement I123V occurred independently on four branches, and the replacements L99M, L266V and I286V occurred each on two branches. The multiple parallel amino acid replacements that occurred in the evolution of bat RH1 suggest the possibility of multiple convergences of their ecological specialization (i.e., various photic environments during adaptation for the nocturnal lifestyle, and suggest that further attention is needed on the study of the ecology and behavior of bats.

  8. Does morphological convergence imply functional similarity? A test using the evolution of quadrupedalism in ornithischian dinosaurs.

    Science.gov (United States)

    Maidment, Susannah C R; Barrett, Paul M

    2012-09-22

    Convergent morphologies are thought to indicate functional similarity, arising because of a limited number of evolutionary or developmental pathways. Extant taxa displaying convergent morphologies are used as analogues to assess function in extinct taxa with similar characteristics. However, functional studies of extant taxa have shown that functional similarity can arise from differing morphologies, calling into question the paradigm that form and function are closely related. We test the hypothesis that convergent skeletal morphology indicates functional similarity in the fossil record using ornithischian dinosaurs. The rare transition from bipedality to quadrupedality occurred at least three times independently in this clade, resulting in a suite of convergent osteological characteristics. We use homology rather than analogy to provide an independent line of evidence about function, reconstructing soft tissues using the extant phylogenetic bracket and applying biomechanical concepts to produce qualitative assessments of muscle leverage. We also optimize character changes to investigate the sequence of character acquisition. Different lineages of quadrupedal ornithischian dinosaur stood and walked differently from each other, falsifying the hypothesis that osteological convergence indicates functional similarity. The acquisition of features correlated with quadrupedalism generally occurs in the same order in each clade, suggesting underlying developmental mechanisms that act as evolutionary constraints.

  9. Septa and processes: convergent evolution of the orbit in haplorhine primates and strigiform birds.

    Science.gov (United States)

    Menegaz, Rachel A; Kirk, E Christopher

    2009-12-01

    According to the "nocturnal visual predation hypothesis" (NVPH), the convergent eyes and orbits of primates result from selection for improved stereoscopic depth perception to facilitate manual capture of prey at night. Within primates, haplorhines share additional derived orbital morphologies, including a postorbital septum and greater orbital convergence than any other mammalian clade. While the homology and function of the haplorhine septum remain controversial, experimental data suggest that septa evolved to inhibit mechanical disturbance of the orbital contents by the anterior temporalis muscle during mastication. According to this "insulation hypothesis," haplorhines are particularly susceptible to disruption of the orbital contents because they have large and highly convergent eyes and orbits. However, comparative tests of the insulation hypothesis have been hindered by the morphological uniqueness of the haplorhine septum among mammals. Among birds, owls (Strigiformes) exhibit an expanded postorbital process that may be functionally analogous to the haplorhine septum. Here we present a comparative analysis of orbital morphology in 103 avian species that tests two hypotheses: (1) large, convergent orbits are associated with nocturnal visual predation, and (2) the strigiform postorbital process and haplorhine postorbital septum similarly function to insulate the eyes from contractions of mandibular adductors. Strigiforms, as nocturnal visual predators, possess relatively large orbits and exhibit the highest degree of orbital convergence in our sample. Notably, orbital convergence does not scale with orbit size in birds as in mammals. Owls are also unique among the birds examined in possessing extensive, plate-like postorbital processes that largely isolate the orbits from the temporal fossae. Furthermore, dissections of four owl species demonstrate that the expanded strigiform postorbital process deflects the path of mandibular adductors around the eye

  10. Convergent Evolution of Syringyl Lignin Biosynthesis via Distinct Pathways in the Lycophyte Selaginella and Flowering Plants[C][W

    Science.gov (United States)

    Weng, Jing-Ke; Akiyama, Takuya; Bonawitz, Nicholas D.; Li, Xu; Ralph, John; Chapple, Clint

    2010-01-01

    Phenotypic convergence in unrelated lineages arises when different organisms adapt similarly under comparable selective pressures. In an apparent example of this process, syringyl lignin, a fundamental building block of plant cell walls, occurs in two major plant lineages, lycophytes and angiosperms, which diverged from one another more than 400 million years ago. Here, we show that this convergence resulted from independent recruitment of lignin biosynthetic cytochrome P450-dependent monooxygenases that route cell wall monomers through related but distinct pathways in the two lineages. In contrast with angiosperms, in which syringyl lignin biosynthesis requires two phenylpropanoid meta-hydroxylases C3′H and F5H, the lycophyte Selaginella employs one phenylpropanoid dual meta-hydroxylase to bypass several steps of the canonical lignin biosynthetic pathway. Transgenic expression of the Selaginella hydroxylase in Arabidopsis thaliana dramatically reroutes its endogenous lignin biosynthetic pathway, yielding a novel lignin composition not previously identified in nature. Our findings demonstrate a unique case of convergent evolution via distinct biochemical strategies and suggest a new way to genetically reconstruct lignin biosynthesis in higher plants. PMID:20371642

  11. Right-handed snakes: convergent evolution of asymmetry for functional specialization

    OpenAIRE

    Hoso, Masaki; Asami, Takahiro; Hori, Michio

    2007-01-01

    External asymmetry found in diverse animals bears critical functions to fulfil ecological requirements. Some snail-eating arthropods exhibit directional asymmetry in their feeding apparatus for foraging efficiency because dextral (clockwise) species are overwhelmingly predominant in snails. Here, we show convergence of directional asymmetry in the dentition of snail-eating vertebrates. We found that snakes in the subfamily Pareatinae, except for non-snail-eating specialists, have more teeth o...

  12. Functional divergence and convergent evolution in the plastid-targeted glyceraldehyde-3-phosphate dehydrogenases of diverse eukaryotic algae.

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    Daniel Gaston

    Full Text Available BACKGROUND: Glyceraldehyde-3-phosphate dehydrogenase (GAPDH is a key enzyme of the glycolytic pathway, reversibly catalyzing the sixth step of glycolysis and concurrently reducing the coenzyme NAD(+ to NADH. In photosynthetic organisms a GAPDH paralog (Gap2 in Cyanobacteria, GapA in most photosynthetic eukaryotes functions in the Calvin cycle, performing the reverse of the glycolytic reaction and using the coenzyme NADPH preferentially. In a number of photosynthetic eukaryotes that acquired their plastid by the secondary endosymbiosis of a eukaryotic red alga (Alveolates, haptophytes, cryptomonads and stramenopiles GapA has been apparently replaced with a paralog of the host's own cytosolic GAPDH (GapC1. Plastid GapC1 and GapA therefore represent two independent cases of functional divergence and adaptations to the Calvin cycle entailing a shift in subcellular targeting and a shift in binding preference from NAD(+ to NADPH. METHODS: We used the programs FunDi, GroupSim, and Difference Evolutionary-Trace to detect sites involved in the functional divergence of these two groups of GAPDH sequences and to identify potential cases of convergent evolution in the Calvin-cycle adapted GapA and GapC1 families. Sites identified as being functionally divergent by all or some of these programs were then investigated with respect to their possible roles in the structure and function of both glycolytic and plastid-targeted GAPDH isoforms. CONCLUSIONS: In this work we found substantial evidence for convergent evolution in GapA/B and GapC1. In many cases sites in GAPDHs of these groups converged on identical amino acid residues in specific positions of the protein known to play a role in the function and regulation of plastid-functioning enzymes relative to their cytosolic counterparts. In addition, we demonstrate that bioinformatic software like FunDi are important tools for the generation of meaningful biological hypotheses that can then be tested with direct

  13. Functional divergence and convergent evolution in the plastid-targeted glyceraldehyde-3-phosphate dehydrogenases of diverse eukaryotic algae.

    Science.gov (United States)

    Gaston, Daniel; Roger, Andrew J

    2013-01-01

    Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a key enzyme of the glycolytic pathway, reversibly catalyzing the sixth step of glycolysis and concurrently reducing the coenzyme NAD(+) to NADH. In photosynthetic organisms a GAPDH paralog (Gap2 in Cyanobacteria, GapA in most photosynthetic eukaryotes) functions in the Calvin cycle, performing the reverse of the glycolytic reaction and using the coenzyme NADPH preferentially. In a number of photosynthetic eukaryotes that acquired their plastid by the secondary endosymbiosis of a eukaryotic red alga (Alveolates, haptophytes, cryptomonads and stramenopiles) GapA has been apparently replaced with a paralog of the host's own cytosolic GAPDH (GapC1). Plastid GapC1 and GapA therefore represent two independent cases of functional divergence and adaptations to the Calvin cycle entailing a shift in subcellular targeting and a shift in binding preference from NAD(+) to NADPH. We used the programs FunDi, GroupSim, and Difference Evolutionary-Trace to detect sites involved in the functional divergence of these two groups of GAPDH sequences and to identify potential cases of convergent evolution in the Calvin-cycle adapted GapA and GapC1 families. Sites identified as being functionally divergent by all or some of these programs were then investigated with respect to their possible roles in the structure and function of both glycolytic and plastid-targeted GAPDH isoforms. In this work we found substantial evidence for convergent evolution in GapA/B and GapC1. In many cases sites in GAPDHs of these groups converged on identical amino acid residues in specific positions of the protein known to play a role in the function and regulation of plastid-functioning enzymes relative to their cytosolic counterparts. In addition, we demonstrate that bioinformatic software like FunDi are important tools for the generation of meaningful biological hypotheses that can then be tested with direct experimental techniques.

  14. The evolution of forearc structures along an oblique convergent margin, central Aleutian Arc

    Science.gov (United States)

    Ryan, H.F.; Scholl, D. W.

    1989-01-01

    Multichannel seismic reflection data were used to determine the evolutionary history of the forearc region of the central Aleutian Ridge. Since at least late Miocene time this sector of the ridge has been obliquely underthrust 30?? west of orthogonal convergence by the northwestward converging Pacific plate at a rate of 80-90 km/m.y. Our data indicate that prior to late Eocene time the forearc region was composed of rocks of the arc massif thinly mantled by slope deposits. Beginning in latest Miocene or earliest Pliocene time, a zone of outer-arc structural highs and a forearc basin began to form. Initial structures of the zone of outer-arc highs formed as the thickening wedge underran, compressively deformed, and uplifted the seaward edge of the arc massive above a landward dipping backstop thrust. Forearc basin strata ponded arcward of the elevating zone of outer-arc highs. However, most younger structures of the zone of outer-arc highs cannot be ascribed simply to the orthogonal effects of an underrunning wedge. Oblique convergence created a major right-lateral shear zone (the Hawley Ridge shear zone) that longitudinally disrupted the zone of outer-arc highs, truncating the seaward flank of the forearc basin and shearing the southern limb of Hawley Ridge, an exceptionally large antiformal outer-arc high structure. Uplift of Hawley Ridge may be related to the thickening of the arc massif by westward directed basement duplexes. Great structural complexity, including the close juxtaposition of coeval structures recording compression, extension, differential vertical movements, and strike-slip displacement, should be expected, even within areas of generally kindred tectonostratigraphic terranes. -from Authors

  15. Convergent evolution of SWS2 opsin facilitates adaptive radiation of threespine stickleback into different light environments.

    Directory of Open Access Journals (Sweden)

    David A Marques

    2017-04-01

    Full Text Available Repeated adaptation to a new environment often leads to convergent phenotypic changes whose underlying genetic mechanisms are rarely known. Here, we study adaptation of color vision in threespine stickleback during the repeated postglacial colonization of clearwater and blackwater lakes in the Haida Gwaii archipelago. We use whole genomes from 16 clearwater and 12 blackwater populations, and a selection experiment, in which stickleback were transplanted from a blackwater lake into an uninhabited clearwater pond and resampled after 19 y to test for selection on cone opsin genes. Patterns of haplotype homozygosity, genetic diversity, site frequency spectra, and allele-frequency change support a selective sweep centered on the adjacent blue- and red-light sensitive opsins SWS2 and LWS. The haplotype under selection carries seven amino acid changes in SWS2, including two changes known to cause a red-shift in light absorption, and is favored in blackwater lakes but disfavored in the clearwater habitat of the transplant population. Remarkably, the same red-shifting amino acid changes occurred after the duplication of SWS2 198 million years ago, in the ancestor of most spiny-rayed fish. Two distantly related fish species, bluefin killifish and black bream, express these old paralogs divergently in black- and clearwater habitats, while sticklebacks lost one paralog. Our study thus shows that convergent adaptation to the same environment can involve the same genetic changes on very different evolutionary time scales by reevolving lost mutations and reusing them repeatedly from standing genetic variation.

  16. Body plan convergence in the evolution of skates and rays (Chondrichthyes: Batoidea).

    Science.gov (United States)

    Aschliman, Neil C; Nishida, Mutsumi; Miya, Masaki; Inoue, Jun G; Rosana, Kerri M; Naylor, Gavin J P

    2012-04-01

    Skates, rays and allies (Batoidea) comprise more than half of the species diversity and much of the morphological disparity among chondrichthyan fishes, the sister group to all other jawed vertebrates. While batoids are morphologically well characterized and have an excellent fossil record, there is currently no consensus on the interrelationships of family-level taxa. Here we construct a resolved, robust and time-calibrated batoid phylogeny using mitochondrial genomes, nuclear genes, and fossils, sampling densely across taxa. Data partitioning schemes, biases in the sequence data, and the relative informativeness of each fossil are explored. The molecular phylogeny is largely congruent with morphology crownward in the tree, but the branching orders of major batoid groups are mostly novel. Body plan convergence appears to be widespread in batoids. A depressed, rounded pectoral disk supported to the snout tip by fin radials, common to skates and stingrays, is indicated to have been derived independently by each group, while the long, spiny rostrum of sawfishes similarly appears to be convergent with that of sawsharks, which are not batoids. The major extant batoid lineages are inferred to have arisen relatively rapidly from the Late Triassic into the Jurassic, with long stems followed by subsequent radiations in each group around the Cretaceous/Tertiary boundary. The fossil record indicates that batoids were affected with disproportionate severity by the end-Cretaceous extinction event. Copyright © 2011 Elsevier Inc. All rights reserved.

  17. Convergent evolution of floral signals underlies the success of Neotropical orchids.

    Science.gov (United States)

    Papadopulos, Alexander S T; Powell, Martyn P; Pupulin, Franco; Warner, Jorge; Hawkins, Julie A; Salamin, Nicolas; Chittka, Lars; Williams, Norris H; Whitten, W Mark; Loader, Deniz; Valente, Luis M; Chase, Mark W; Savolainen, Vincent

    2013-08-22

    The great majority of plant species in the tropics require animals to achieve pollination, but the exact role of floral signals in attraction of animal pollinators is often debated. Many plants provide a floral reward to attract a guild of pollinators, and it has been proposed that floral signals of non-rewarding species may converge on those of rewarding species to exploit the relationship of the latter with their pollinators. In the orchid family (Orchidaceae), pollination is almost universally animal-mediated, but a third of species provide no floral reward, which suggests that deceptive pollination mechanisms are prevalent. Here, we examine floral colour and shape convergence in Neotropical plant communities, focusing on certain food-deceptive Oncidiinae orchids (e.g. Trichocentrum ascendens and Oncidium nebulosum) and rewarding species of Malpighiaceae. We show that the species from these two distantly related families are often more similar in floral colour and shape than expected by chance and propose that a system of multifarious floral mimicry--a form of Batesian mimicry that involves multiple models and is more complex than a simple one model-one mimic system--operates in these orchids. The same mimetic pollination system has evolved at least 14 times within the species-rich Oncidiinae throughout the Neotropics. These results help explain the extraordinary diversification of Neotropical orchids and highlight the complexity of plant-animal interactions.

  18. Convergent evolution of SWS2 opsin facilitates adaptive radiation of threespine stickleback into different light environments.

    Science.gov (United States)

    Marques, David A; Taylor, John S; Jones, Felicity C; Di Palma, Federica; Kingsley, David M; Reimchen, Thomas E

    2017-04-01

    Repeated adaptation to a new environment often leads to convergent phenotypic changes whose underlying genetic mechanisms are rarely known. Here, we study adaptation of color vision in threespine stickleback during the repeated postglacial colonization of clearwater and blackwater lakes in the Haida Gwaii archipelago. We use whole genomes from 16 clearwater and 12 blackwater populations, and a selection experiment, in which stickleback were transplanted from a blackwater lake into an uninhabited clearwater pond and resampled after 19 y to test for selection on cone opsin genes. Patterns of haplotype homozygosity, genetic diversity, site frequency spectra, and allele-frequency change support a selective sweep centered on the adjacent blue- and red-light sensitive opsins SWS2 and LWS. The haplotype under selection carries seven amino acid changes in SWS2, including two changes known to cause a red-shift in light absorption, and is favored in blackwater lakes but disfavored in the clearwater habitat of the transplant population. Remarkably, the same red-shifting amino acid changes occurred after the duplication of SWS2 198 million years ago, in the ancestor of most spiny-rayed fish. Two distantly related fish species, bluefin killifish and black bream, express these old paralogs divergently in black- and clearwater habitats, while sticklebacks lost one paralog. Our study thus shows that convergent adaptation to the same environment can involve the same genetic changes on very different evolutionary time scales by reevolving lost mutations and reusing them repeatedly from standing genetic variation.

  19. Right-handed snakes: convergent evolution of asymmetry for functional specialization.

    Science.gov (United States)

    Hoso, Masaki; Asami, Takahiro; Hori, Michio

    2007-04-22

    External asymmetry found in diverse animals bears critical functions to fulfil ecological requirements. Some snail-eating arthropods exhibit directional asymmetry in their feeding apparatus for foraging efficiency because dextral (clockwise) species are overwhelmingly predominant in snails. Here, we show convergence of directional asymmetry in the dentition of snail-eating vertebrates. We found that snakes in the subfamily Pareatinae, except for non-snail-eating specialists, have more teeth on the right mandible than the left. In feeding experiments, a snail-eating specialist Pareas iwasakii completed extracting a dextral soft body faster with fewer mandible retractions than a sinistral body. The snakes failed in holding and dropped sinistral snails more often owing to behavioural asymmetry when striking. Our results demonstrate that symmetry break in dentition is a key innovation that has opened a unique ecological niche for snake predators.

  20. Parallel domestication, convergent evolution and duplicated gene recruitment in allopolyploid cotton.

    Science.gov (United States)

    Hovav, Ran; Chaudhary, Bhupendra; Udall, Joshua A; Flagel, Lex; Wendel, Jonathan F

    2008-07-01

    A putative advantage of allopolyploidy is the possibility of differential selection of duplicated (homeologous) genes originating from two different progenitor genomes. In this note we explore this hypothesis using a high throughput, SNP-specific microarray technology applied to seed trichomes (cotton) harvested from three developmental time points in wild and modern accessions of two independently domesticated cotton species, Gossypium hirsutum and G. barbadense. We show that homeolog expression ratios are dynamic both developmentally and over the several-thousand-year period encompassed by domestication and crop improvement, and that domestication increased the modulation of homeologous gene expression. In both species, D-genome expression was preferentially enhanced under human selection pressure, but for nonoverlapping sets of genes for the two independent domestication events. Our data suggest that human selection may have operated on different components of the fiber developmental genetic program in G. hirsutum and G. barbadense, leading to convergent rather than parallel genetic alterations and resulting morphology.

  1. Convergent evolution of argonaute-2 slicer antagonism in two distinct insect RNA viruses.

    NARCIS (Netherlands)

    Mierlo, J.T. van; Bronkhorst, A.W.; Overheul, G.J.; Sadanandan, S.A.; Ekstrom, J.O.; Heestermans, M.; Hultmark, D.; Antoniewski, C.; Rij, R.P. van

    2012-01-01

    RNA interference (RNAi) is a major antiviral pathway that shapes evolution of RNA viruses. We show here that Nora virus, a natural Drosophila pathogen, is both a target and suppressor of RNAi. We detected viral small RNAs with a signature of Dicer-2 dependent small interfering RNAs in Nora virus

  2. Adaptation, niche conservatism, and convergence: comparative studies of leaf evolution in the California chaparral.

    Science.gov (United States)

    Ackerly, David D

    2004-05-01

    Small leaves and low specific leaf area (SLA) have long been viewed as adaptations to Mediterranean-type climates in many species of evergreen woody plants. However, paleobotanical and floristic evidence suggests that in many cases these traits originated prior to the advent of the summer-drought climate regime. In this study, molecular phylogenies and ancestral state reconstructions were used to test the hypothesis of adaptive leaf evolution in 12 lineages of evergreen shrubs in the California chaparral. Across all lineages there was a small but significant shift toward lower SLA, but there were no trends in leaf size evolution. For individual lineages, adaptive changes were detected in only three cases for SLA and in one case for leaf size. Three of these cases of evolutionary change were observed in taxa derived from cool temperate ancestors (e.g., Heteromeles). In contrast, most lineages originating from subtropical ancestors exhibited relative stasis in leaf trait evolution (e.g., Ceanothus). The absence of change suggests that ancestors of chaparral taxa had already acquired appropriate traits that contributed to their success under Mediterranean-type climates. These results illustrate how biogeographic history may influence patterns of trait evolution and adaptation and highlight the contribution of ecological sorting processes to the assembly and functional ecology of regional biotas.

  3. Effects of temporal density variation and convergent geometry on nonlinear bubble evolution in classical Rayleigh-Taylor instability.

    Science.gov (United States)

    Goncharov, V N; Li, D

    2005-04-01

    Effects of temporal density variation and spherical convergence on the nonlinear bubble evolution of single-mode, classical Rayleigh-Taylor instability are studied using an analytical model based on Layzer's theory [Astrophys. J. 122, 1 (1955)]. When the temporal density variation is included, the bubble amplitude in planar geometry is shown to asymptote to integral(t)U(L)(t')rho(t')dt'/rho(t), where U(L) = square root of (g/(C(g)k)) is the Layzer bubble velocity, rho is the fluid density, and C(g) = 3 and C(g) = 1 for the two- and three-dimensional geometries, respectively. The asymptotic bubble amplitude in a converging spherical shell is predicted to evolve as eta approximately etam(-/r0//(lU(L)sp-eta/r0), where r0 is the outer shell radius, eta(t) = integral(t)U(L)sp(t')rho(t') r(0)2(t')dt'/rho(t)r(0)2(t), U(L)(sp) = square root of (-r0(t)r0(t)/l), m(t) = rho(t)r(0)3(t), and l is the mode number.

  4. Convergent evolution within the genus Solanum: the specialised anther cone develops through alternative pathways.

    Science.gov (United States)

    Glover, Beverley J; Bunnewell, Sue; Martin, Cathie

    2004-04-28

    Many angiosperm species produce cones of anthers which release pollen through pores in response to vibration by pollinating bees ("buzz-pollination"). Anther cones of varying degrees of strength are a defining morphological trait for the genus Solanum. Anthers arranged in a robust ('pepper pot') cone are restricted to a single clade within the genus, and may therefore be assumed to be monophyletic. We show that in some species within this clade, such as tomato (Solanum lycopersicum), the anther cone is held together by interlocking hairs (trichomes) along the edges of the anthers. In other species within the clade, such as woody nightshade (Solanum dulcamara), the expanded anther surfaces are closely appressed to form the tightly bound cone, strengthened by extracellular secretions. Ectopic expression of the MIXTA gene from Antirrhinum majus in S. dulcamara results in the formation of ectopic trichomes on the anthers which cause the cone to disintegrate. Therefore, these two species produce the same macroscopic structure through two mutually exclusive developmental routes and the robust anther cone is derived differently within the clade. This example demonstrates that convergence between closely related species can be easily mistaken for homology, and may thus be underestimated.

  5. Convergent evolution of neuroendocrine control of phenotypic plasticity in pupal colour in butterflies

    Science.gov (United States)

    Starnecker, G.; Hazel, W.

    1999-01-01

    Phenotypic plasticity in pupal colour occurs in three families of butterflies (the Nymphalidae, Papilionidae and Pieridae), typically in species whose pupation sites vary unpredictably in colour. In all species studied to date, larvae ready for pupation respond to environmental cues associated with the colour of their pupation sites and moult into cryptic light (yellow–green) or dark (brown–black) pupae. In nymphalids and pierids, pupal colour is controlled by a neuroendocrine factor, pupal melanization-reducing factor (PMRF), the release of which inhibits the melanization of the pupal cuticle resulting in light pupae. In contrast, the neuroendocrine factor controlling pupal colour in papilionid butterflies results in the production of brown pupae. PMRF was extracted from the ventral nerve chains of the peacock butterfly Inachis io (Nymphalidae) and black swallowtail butterfly Papilio polyxenes (Papilionidae). When injected into pre-pupae, the extracts resulted in yellow pupae in I. io but brown pupae in P. polyxenes. These results suggest that the same neuroendocrine factor controls the plasticity in pupal colour, but that plasticity in pupal colour in these species has evolved independently (convergently).

  6. Convergent evolution of jaws between spinosaurid dinosaurs and pike conger eels

    Directory of Open Access Journals (Sweden)

    Romain Vullo

    2016-12-01

    Full Text Available Spinosaurs represent a group of peculiar theropod dinosaurs that have often been described as “crocodile-mimic”, predominantly fish-eating predators, and recently claimed to have been semi-aquatic animals. Here we report a suite of craniodental characters unexpectedly shared by spinosaurs and pike conger eels. Pike conger eels are predatory, mainly piscivorous bottom-dwelling anguilliform fishes that inhabit marine and brackish environments. These two groups of dinosaurs and fishes show a mediolaterally compressed, elongated rostrum, a terminal “rosette” bearing enlarged teeth in both upper and lower jaws, and a notch posterior to the premaxillary “rosette” characterized by the presence of reduced teeth. The morphological convergence observed in the jaws of these two distantly related groups of vertebrates may result from similar feeding behaviours. This typical jaw morphology likely represents an effective biomechanical adaptation for biting and grabbing elusive prey items in low-light aquatic environments. Associated with this specialized snout morphology, numerous integumentary mechanoreceptors involved in prey detection are present in both spinosaurs and pike congers. Our new observations provide an additional convincing argument regarding the decades-long and widely debated lifestyle of spinosaurs.

  7. Convergent Evolution of Pathogen Effectors toward Reactive Oxygen Species Signaling Networks in Plants

    Directory of Open Access Journals (Sweden)

    Nam-Soo Jwa

    2017-09-01

    Full Text Available Microbial pathogens have evolved protein effectors to promote virulence and cause disease in host plants. Pathogen effectors delivered into plant cells suppress plant immune responses and modulate host metabolism to support the infection processes of pathogens. Reactive oxygen species (ROS act as cellular signaling molecules to trigger plant immune responses, such as pathogen-associated molecular pattern (PAMP-triggered immunity (PTI and effector-triggered immunity. In this review, we discuss recent insights into the molecular functions of pathogen effectors that target multiple steps in the ROS signaling pathway in plants. The perception of PAMPs by pattern recognition receptors leads to the rapid and strong production of ROS through activation of NADPH oxidase Respiratory Burst Oxidase Homologs (RBOHs as well as peroxidases. Specific pathogen effectors directly or indirectly interact with plant nucleotide-binding leucine-rich repeat receptors to induce ROS production and the hypersensitive response in plant cells. By contrast, virulent pathogens possess effectors capable of suppressing plant ROS bursts in different ways during infection. PAMP-triggered ROS bursts are suppressed by pathogen effectors that target mitogen-activated protein kinase cascades. Moreover, pathogen effectors target vesicle trafficking or metabolic priming, leading to the suppression of ROS production. Secreted pathogen effectors block the metabolic coenzyme NADP-malic enzyme, inhibiting the transfer of electrons to the NADPH oxidases (RBOHs responsible for ROS generation. Collectively, pathogen effectors may have evolved to converge on a common host protein network to suppress the common plant immune system, including the ROS burst and cell death response in plants.

  8. Convergent Evolution of Pathogen Effectors toward Reactive Oxygen Species Signaling Networks in Plants.

    Science.gov (United States)

    Jwa, Nam-Soo; Hwang, Byung Kook

    2017-01-01

    Microbial pathogens have evolved protein effectors to promote virulence and cause disease in host plants. Pathogen effectors delivered into plant cells suppress plant immune responses and modulate host metabolism to support the infection processes of pathogens. Reactive oxygen species (ROS) act as cellular signaling molecules to trigger plant immune responses, such as pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) and effector-triggered immunity. In this review, we discuss recent insights into the molecular functions of pathogen effectors that target multiple steps in the ROS signaling pathway in plants. The perception of PAMPs by pattern recognition receptors leads to the rapid and strong production of ROS through activation of NADPH oxidase Respiratory Burst Oxidase Homologs (RBOHs) as well as peroxidases. Specific pathogen effectors directly or indirectly interact with plant nucleotide-binding leucine-rich repeat receptors to induce ROS production and the hypersensitive response in plant cells. By contrast, virulent pathogens possess effectors capable of suppressing plant ROS bursts in different ways during infection. PAMP-triggered ROS bursts are suppressed by pathogen effectors that target mitogen-activated protein kinase cascades. Moreover, pathogen effectors target vesicle trafficking or metabolic priming, leading to the suppression of ROS production. Secreted pathogen effectors block the metabolic coenzyme NADP-malic enzyme, inhibiting the transfer of electrons to the NADPH oxidases (RBOHs) responsible for ROS generation. Collectively, pathogen effectors may have evolved to converge on a common host protein network to suppress the common plant immune system, including the ROS burst and cell death response in plants.

  9. Viral inhibition of the transporter associated with antigen processing (TAP: a striking example of functional convergent evolution.

    Directory of Open Access Journals (Sweden)

    Marieke C Verweij

    2015-04-01

    convergent evolution.

  10. Convergent evolution of morphology and habitat use in the explosive Hawaiian fancy case caterpillar radiation.

    Science.gov (United States)

    Kawahara, A Y; Rubinoff, D

    2013-08-01

    Species occurring in unconnected, but similar habitats and under similar selection pressures often display strikingly comparable morphology, behaviour and life history. On island archipelagos where colonizations and extinctions are common, it is often difficult to separate whether similar traits are a result of in situ diversification or independent colonization without a phylogeny. Here, we use one of Hawaii's most ecologically diverse and explosive endemic species radiations, the Hawaiian fancy case caterpillar genus Hyposmocoma, to test whether in situ diversification resulted in convergence. Specifically, we examine whether similar species utilizing similar microhabitats independently developed largely congruent larval case phenotypes in lineages that are in comparable, but isolated environments. Larvae of these moths are found on all Hawaiian Islands and are characterized by an extraordinary array of ecomorphs and larval case morphology. We focus on the 'purse cases', a group that is largely specialized for living within rotting wood. Purse cases were considered a monophyletic group, because morphological, behavioural and ecological traits appeared to be shared among all members. We constructed a phylogeny based on nuclear and mitochondrial DNA sequences from 38 Hyposmocoma species, including all 14 purse case species and 24 of non-purse case congeners. Divergence time estimation suggests that purse case lineages evolved independently within dead wood and developed nearly identical case morphology twice: once on the distant Northwest Hawaiian Islands between 15.5 and 9 Ma and once on the younger main Hawaiian Islands around 3.0 Ma. Multiple ecomorphs are usually found on each island, and the ancestral ecomorph of Hyposmocoma appears to have lived on tree bark. Unlike most endemic Hawaiian radiations that follow a clear stepwise progression of colonization, purse case Hyposmocoma do not follow a pattern of colonization from older to younger island. We

  11. Convergent evolution of a fused sexual cycle promotes the haploid lifestyle

    Science.gov (United States)

    Sherwood, Racquel Kim; Scaduto, Christine M.; Torres, Sandra E.; Bennett, Richard J.

    2014-02-01

    Sexual reproduction is restricted to eukaryotic species and involves the fusion of haploid gametes to form a diploid cell that subsequently undergoes meiosis to generate recombinant haploid forms. This process has been extensively studied in the unicellular yeast Saccharomyces cerevisiae, which exhibits separate regulatory control over mating and meiosis. Here we address the mechanism of sexual reproduction in the related hemiascomycete species Candida lusitaniae. We demonstrate that, in contrast to S. cerevisiae, C. lusitaniae exhibits a highly integrated sexual program in which the programs regulating mating and meiosis have fused. Profiling of the C. lusitaniae sexual cycle revealed that gene expression patterns during mating and meiosis were overlapping, indicative of co-regulation. This was particularly evident for genes involved in pheromone MAPK signalling, which were highly induced throughout the sexual cycle of C. lusitaniae. Furthermore, genetic analysis showed that the orthologue of IME2, a `diploid-specific' factor in S. cerevisiae, and STE12, the master regulator of S. cerevisiae mating, were each required for progression through both mating and meiosis in C. lusitaniae. Together, our results establish that sexual reproduction has undergone significant rewiring between S. cerevisiae and C. lusitaniae, and that a concerted sexual cycle operates in C. lusitaniae that is more reminiscent of the distantly related ascomycete, Schizosaccharomyces pombe. We discuss these results in light of the evolution of sexual reproduction in yeast, and propose that regulatory coupling of mating and meiosis has evolved multiple times as an adaptation to promote the haploid lifestyle.

  12. Deceptive desmas: molecular phylogenetics suggests a new classification and uncovers convergent evolution of lithistid demosponges.

    Directory of Open Access Journals (Sweden)

    Astrid Schuster

    Full Text Available Reconciling the fossil record with molecular phylogenies to enhance the understanding of animal evolution is a challenging task, especially for taxa with a mostly poor fossil record, such as sponges (Porifera. 'Lithistida', a polyphyletic group of recent and fossil sponges, are an exception as they provide the richest fossil record among demosponges. Lithistids, currently encompassing 13 families, 41 genera and >300 recent species, are defined by the common possession of peculiar siliceous spicules (desmas that characteristically form rigid articulated skeletons. Their phylogenetic relationships are to a large extent unresolved and there has been no (taxonomically comprehensive analysis to formally reallocate lithistid taxa to their closest relatives. This study, based on the most comprehensive molecular and morphological investigation of 'lithistid' demosponges to date, corroborates some previous weakly-supported hypotheses, and provides novel insights into the evolutionary relationships of the previous 'order Lithistida'. Based on molecular data (partial mtDNA CO1 and 28S rDNA sequences, we show that 8 out of 13 'Lithistida' families belong to the order Astrophorida, whereas Scleritodermidae and Siphonidiidae form a separate monophyletic clade within Tetractinellida. Most lithistid astrophorids are dispersed between different clades of the Astrophorida and we propose to formally reallocate them, respectively. Corallistidae, Theonellidae and Phymatellidae are monophyletic, whereas the families Pleromidae and Scleritodermidae are polyphyletic. Family Desmanthidae is polyphyletic and groups within Halichondriidae--we formally propose a reallocation. The sister group relationship of the family Vetulinidae to Spongillida is confirmed and we propose here for the first time to include Vetulina into a new Order Sphaerocladina. Megascleres and microscleres possibly evolved and/or were lost several times independently in different 'lithistid' taxa, and

  13. Microbat paraphyly and the convergent evolution of a key innovation in Old World rhinolophoid microbats.

    Science.gov (United States)

    Teeling, Emma C; Madsen, Ole; Van den Bussche, Ronald A; de Jong, Wilfried W; Stanhope, Michael J; Springer, Mark S

    2002-02-05

    Molecular phylogenies challenge the view that bats belong to the superordinal group Archonta, which also includes primates, tree shrews, and flying lemurs. Some molecular studies also challenge microbat monophyly and instead support an alliance between megabats and representative rhinolophoid microbats from the families Rhinolophidae (horseshoe bats, Old World leaf-nosed bats) and Megadermatidae (false vampire bats). Another molecular study ostensibly contradicts these results and supports traditional microbat monophyly, inclusive of representative rhinolophoids from the family Nycteridae (slit-faced bats). Resolution of the microbat paraphyly/monophyly issue is essential for reconstructing the temporal sequence and deployment of morphological character state changes associated with flight and echolocation in bats. If microbats are paraphyletic, then laryngeal echolocation either evolved more than once in different microbats or was lost in megabats after evolving in the ancestor of all living bats. To examine these issues, we used a 7.1-kb nuclear data set for nine outgroups and twenty bats, including representatives of all rhinolophoid families. Phylogenetic analyses and statistical tests rejected both Archonta and microbat monophyly. Instead, bats are in the superorder Laurasiatheria and microbats are paraphyletic. Further, the superfamily Rhinolophoidea is polyphyletic. The rhinolophoid families Rhinolophidae and Megadermatidae belong to the suborder Yinpterochiroptera along with rhinopomatids and megabats. The rhinolophoid family Nycteridae belongs to the suborder Yangochiroptera along with vespertilionoids, noctilionoids, and emballonuroids. These results resolve the apparent conflict between previous molecular studies that sampled different rhinolophoid families. An important implication of rhinolophoid polyphyly is independent evolution of key anatomical innovations associated with the nasal-emission of echolocation pulses.

  14. A eukaryotic nicotinate-inducible gene cluster: convergent evolution in fungi and bacteria

    Science.gov (United States)

    Ámon, Judit; Fernández-Martín, Rafael; Bokor, Eszter; Cultrone, Antonietta; Kelly, Joan M.; Flipphi, Michel; Scazzocchio, Claudio

    2017-01-01

    Nicotinate degradation has hitherto been elucidated only in bacteria. In the ascomycete Aspergillus nidulans, six loci, hxnS/AN9178 encoding the molybdenum cofactor-containing nicotinate hydroxylase, AN11197 encoding a Cys2/His2 zinc finger regulator HxnR, together with AN11196/hxnZ, AN11188/hxnY, AN11189/hxnP and AN9177/hxnT, are clustered and stringently co-induced by a nicotinate derivative and subject to nitrogen metabolite repression mediated by the GATA factor AreA. These genes are strictly co-regulated by HxnR. Within the hxnR gene, constitutive mutations map in two discrete regions. Aspergillus nidulans is capable of using nicotinate and its oxidation products 6-hydroxynicotinic acid and 2,5-dihydroxypyridine as sole nitrogen sources in an HxnR-dependent way. HxnS is highly similar to HxA, the canonical xanthine dehydrogenase (XDH), and has originated by gene duplication, preceding the origin of the Pezizomycotina. This cluster is conserved with some variations throughout the Aspergillaceae. Our results imply that a fungal pathway has arisen independently from bacterial ones. Significantly, the neo-functionalization of XDH into nicotinate hydroxylase has occurred independently from analogous events in bacteria. This work describes for the first time a gene cluster involved in nicotinate catabolism in a eukaryote and has relevance for the formation and evolution of co-regulated primary metabolic gene clusters and the microbial degradation of N-heterocyclic compounds. PMID:29212709

  15. Three dimensional hydrodynamic calculations with adaptive mesh refinement of the evolution of Rayleigh Taylor and Richtmyer Meshkov instabilities in converging geometry: Multi-mode perturbations

    Energy Technology Data Exchange (ETDEWEB)

    Klein, R.I. [Lawrence Livermore National Lab., CA (US)]|[Univ. of California, Berkeley (US). Dept. of Astronomy; Bell, J.; Pember, R.; Kelleher, T. [Lawrence Livermore National Lab., CA (US)

    1993-04-01

    The authors present results for high resolution hydrodynamic calculations of the growth and development of instabilities in shock driven imploding spherical geometries in both 2D and 3D. They solve the Eulerian equations of hydrodynamics with a high order Godunov approach using local adaptive mesh refinement to study the temporal and spatial development of the turbulent mixing layer resulting from both Richtmyer Meshkov and Rayleigh Taylor instabilities. The use of a high resolution Eulerian discretization with adaptive mesh refinement permits them to study the detailed three-dimensional growth of multi-mode perturbations far into the non-linear regime for converging geometries. They discuss convergence properties of the simulations by calculating global properties of the flow. They discuss the time evolution of the turbulent mixing layer and compare its development to a simple theory for a turbulent mix model in spherical geometry based on Plesset`s equation. Their 3D calculations show that the constant found in the planar incompressible experiments of Read and Young`s may not be universal for converging compressible flow. They show the 3D time trace of transitional onset to a mixing state using the temporal evolution of volume rendered imaging. Their preliminary results suggest that the turbulent mixing layer loses memory of its initial perturbations for classical Richtmyer Meshkov and Rayleigh Taylor instabilities in spherically imploding shells. They discuss the time evolution of mixed volume fraction and the role of vorticity in converging 3D flows in enhancing the growth of a turbulent mixing layer.

  16. Ecology and caudal skeletal morphology in birds: the convergent evolution of pygostyle shape in underwater foraging taxa.

    Directory of Open Access Journals (Sweden)

    Ryan N Felice

    Full Text Available Birds exhibit a specialized tail that serves as an integral part of the flight apparatus, supplementing the role of the wings in facilitating high performance aerial locomotion. The evolution of this function for the tail contributed to the diversification of birds by allowing them to utilize a wider range of flight behaviors and thus exploit a greater range of ecological niches. The shape of the wings and the tail feathers influence the aerodynamic properties of a bird. Accordingly, taxa that habitually utilize different flight behaviors are characterized by different flight apparatus morphologies. This study explores whether differences in flight behavior are also associated with variation in caudal vertebra and pygostyle morphology. Details of the tail skeleton were characterized in 51 Aequornithes and Charadriiformes species. Free caudal vertebral morphology was measured using linear metrics. Variation in pygostyle morphology was characterized using Elliptical Fourier Analysis, a geometric morphometric method for the analysis of outline shapes. Each taxon was categorized based on flight style (flap, flap-glide, dynamic soar, etc. and foraging style (aerial, terrestrial, plunge dive, etc.. Phylogenetic MANOVAs and Flexible Discriminant Analyses were used to test whether caudal skeletal morphology can be used to predict flight behavior. Foraging style groups differ significantly in pygostyle shape, and pygostyle shape predicts foraging style with less than 4% misclassification error. Four distinct lineages of underwater foraging birds exhibit an elongate, straight pygostyle, whereas aerial and terrestrial birds are characterized by a short, dorsally deflected pygostyle. Convergent evolution of a common pygostyle phenotype in diving birds suggests that this morphology is related to the mechanical demands of using the tail as a rudder during underwater foraging. Thus, distinct locomotor behaviors influence not only feather attributes but also

  17. New Ulvan-Degrading Polysaccharide Lyase Family: Structure and Catalytic Mechanism Suggests Convergent Evolution of Active Site Architecture.

    Science.gov (United States)

    Ulaganathan, ThirumalaiSelvi; Boniecki, Michal T; Foran, Elizabeth; Buravenkov, Vitaliy; Mizrachi, Naama; Banin, Ehud; Helbert, William; Cygler, Miroslaw

    2017-05-19

    Ulvan is a complex sulfated polysaccharide biosynthesized by green seaweed and contains predominantly rhamnose, xylose, and uronic acid sugars. Ulvan-degrading enzymes have only recently been identified and added to the CAZy ( www.cazy.org ) database as family PL24, but neither their structure nor catalytic mechanism(s) are yet known. Several homologous, new ulvan lyases, have been discovered in Pseudoalteromonas sp. strain PLSV, Alteromonas LOR, and Nonlabens ulvanivorans, defining a new family PL25, with the lyase encoded by the gene PLSV_3936 being one of them. This enzyme cleaves the glycosidic bond between 3-sulfated rhamnose (R3S) and glucuronic acid (GlcA) or iduronic acid (IdoA) via a β-elimination mechanism. We report the crystal structure of PLSV_3936 and its complex with a tetrasaccharide substrate. PLSV_3936 folds into a seven-bladed β-propeller, with each blade consisting of four antiparallel β-strands. Sequence conservation analysis identified a highly conserved region lining at one end of a deep crevice on the protein surface. The putative active site was identified by mutagenesis and activity measurements. Crystal structure of the enzyme with a bound tetrasaccharide substrate confirmed the identity of base and acid residues and allowed determination of the catalytic mechanism and also the identification of residues neutralizing the uronic acid carboxylic group. The PLSV_3936 structure provides an example of a convergent evolution among polysaccharide lyases toward a common active site architecture embedded in distinct folds.

  18. Ancient mitochondrial DNA reveals convergent evolution of giant short-faced bears (Tremarctinae) in North and South America

    Science.gov (United States)

    Bover, Pere; Soibelzon, Leopoldo; Schubert, Blaine W.; Prevosti, Francisco; Prieto, Alfredo; Martin, Fabiana; Austin, Jeremy J.; Cooper, Alan

    2016-01-01

    The Tremarctinae are a subfamily of bears endemic to the New World, including two of the largest terrestrial mammalian carnivores that have ever lived: the giant, short-faced bears Arctodus simus from North America and Arctotherium angustidens from South America (greater than or equal to 1000 kg). Arctotherium angustidens became extinct during the Early Pleistocene, whereas Arctodus simus went extinct at the very end of the Pleistocene. The only living tremarctine is the spectacled bear (Tremarctos ornatus), a largely herbivorous bear that is today only found in South America. The relationships among the spectacled bears (Tremarctos), South American short-faced bears (Arctotherium) and North American short-faced bears (Arctodus) remain uncertain. In this study, we sequenced a mitochondrial genome from an Arctotherium femur preserved in a Chilean cave. Our molecular phylogenetic analyses revealed that the South American short-faced bears were more closely related to the extant South American spectacled bear than to the North American short-faced bears. This result suggests striking convergent evolution of giant forms in the two groups of short-faced bears (Arctodus and Arctotherium), potentially as an adaptation to dominate competition for megafaunal carcasses. PMID:27095265

  19. A new prey-detection mechanism for kiwi (Apteryx spp.) suggests convergent evolution between paleognathous and neognathous birds.

    Science.gov (United States)

    Cunningham, Susan; Castro, Isabel; Alley, Maurice

    2007-10-01

    Kiwi (Apterygidae: Apteryx spp.) are traditionally assumed to detect their soil-dwelling invertebrate prey using their sense of smell. The unique position of the nares at the tip of the bill and the enlarged olfactory centres in the brain support this assumption. However, studies designed to show the importance of olfaction in prey-detection by Apteryx have provided equivocal results. Another family of probing birds, the Scolopacidae, detect their buried prey using specialised vibration and pressure-sensitive mechanoreceptors embedded in pits in the bill-tip. We found that aspects of the foraging patterns of Apteryx mantelli are like those of scolopacid shorebirds, suggesting that Apteryx may be using a similar prey-detection mechanism. We examined specimens of all five Apteryx species and conducted a morphological and histological examination of the bill of A. mantelli. We discovered that Apteryx possess an arrangement of mechanoreceptors within pits similar to that in Scolopacidae species and may therefore be able to localise prey using a similar vibrotactile sense. We suggest that this sense may function in conjunction with, or be dominant over, olfaction during prey-detection. The Apterygidae and the Scolopacidae are members of the two different super-orders of birds: the Paleognathae and the Neognathae, respectively. Therefore we cite the similar bill-tip anatomy of these two families as an example of convergent evolution across a deep taxonomic divide.

  20. Non-indolyl cruciferous phytoalexins: Nasturlexins and tridentatols, a striking convergent evolution of defenses in terrestrial plants and marine animals?

    Science.gov (United States)

    Pedras, M Soledade C; To, Q Huy

    2015-05-01

    Highly specialized chemical defense pathways are a particularly noteworthy metabolic characteristic of sessile organisms, whether terrestrial or marine, providing protection against pests and diseases. For this reason, knowledge of the metabolites involved in these processes is crucial to producing ecologically fit crops. Toward this end, the elicited chemical defenses of the crucifer watercress (Nasturtium officinale R. Br.), i.e. phytoalexins, were investigated and are reported. Almost three decades after publication of cruciferous phytoalexins derived from (S)-Trp, phytoalexins derived from other aromatic amino acids were isolated; their chemical structures were determined by analyses of their spectroscopic data and confirmed by synthesis. Nasturlexin A, nasturlexin B, and tridentatol C are hitherto unknown phenyl containing cruciferous phytoalexins produced by watercress under abiotic stress; tridentatol C is also produced by a marine animal (Tridentata marginata), where it functions in chemical defense against predators. The biosynthesis of these metabolites in both a terrestrial plant and a marine animal suggests a convergent evolution of unique metabolic pathways recruited for defense. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. A multi-gene phylogeny of Cephalopoda supports convergent morphological evolution in association with multiple habitat shifts in the marine environment.

    Science.gov (United States)

    Lindgren, Annie R; Pankey, Molly S; Hochberg, Frederick G; Oakley, Todd H

    2012-07-28

    The marine environment is comprised of numerous divergent organisms living under similar selective pressures, often resulting in the evolution of convergent structures such as the fusiform body shape of pelagic squids, fishes, and some marine mammals. However, little is known about the frequency of, and circumstances leading to, convergent evolution in the open ocean. Here, we present a comparative study of the molluscan class Cephalopoda, a marine group known to occupy habitats from the intertidal to the deep sea. Several lineages bear features that may coincide with a benthic or pelagic existence, making this a valuable group for testing hypotheses of correlated evolution. To test for convergence and correlation, we generate the most taxonomically comprehensive multi-gene phylogeny of cephalopods to date. We then create a character matrix of habitat type and morphological characters, which we use to infer ancestral character states and test for correlation between habitat and morphology. Our study utilizes a taxonomically well-sampled phylogeny to show convergent evolution in all six morphological characters we analyzed. Three of these characters also correlate with habitat. The presence of an autogenic photophore (those relying upon autonomous enzymatic light reactions) is correlated with a pelagic habitat, while the cornea and accessory nidamental gland correlate with a benthic lifestyle. Here, we present the first statistical tests for correlation between convergent traits and habitat in cephalopods to better understand the evolutionary history of characters that are adaptive in benthic or pelagic environments, respectively. Our study supports the hypothesis that habitat has influenced convergent evolution in the marine environment: benthic organisms tend to exhibit similar characteristics that confer protection from invasion by other benthic taxa, while pelagic organisms possess features that facilitate crypsis and communication in an environment lacking

  2. A multi-gene phylogeny of Cephalopoda supports convergent morphological evolution in association with multiple habitat shifts in the marine environment

    Directory of Open Access Journals (Sweden)

    Lindgren Annie R

    2012-07-01

    Full Text Available Abstract Background The marine environment is comprised of numerous divergent organisms living under similar selective pressures, often resulting in the evolution of convergent structures such as the fusiform body shape of pelagic squids, fishes, and some marine mammals. However, little is known about the frequency of, and circumstances leading to, convergent evolution in the open ocean. Here, we present a comparative study of the molluscan class Cephalopoda, a marine group known to occupy habitats from the intertidal to the deep sea. Several lineages bear features that may coincide with a benthic or pelagic existence, making this a valuable group for testing hypotheses of correlated evolution. To test for convergence and correlation, we generate the most taxonomically comprehensive multi-gene phylogeny of cephalopods to date. We then create a character matrix of habitat type and morphological characters, which we use to infer ancestral character states and test for correlation between habitat and morphology. Results Our study utilizes a taxonomically well-sampled phylogeny to show convergent evolution in all six morphological characters we analyzed. Three of these characters also correlate with habitat. The presence of an autogenic photophore (those relying upon autonomous enzymatic light reactions is correlated with a pelagic habitat, while the cornea and accessory nidamental gland correlate with a benthic lifestyle. Here, we present the first statistical tests for correlation between convergent traits and habitat in cephalopods to better understand the evolutionary history of characters that are adaptive in benthic or pelagic environments, respectively. Discussion Our study supports the hypothesis that habitat has influenced convergent evolution in the marine environment: benthic organisms tend to exhibit similar characteristics that confer protection from invasion by other benthic taxa, while pelagic organisms possess features that

  3. Convergent chaos

    Science.gov (United States)

    Pradas, Marc; Pumir, Alain; Huber, Greg; Wilkinson, Michael

    2017-07-01

    Chaos is widely understood as being a consequence of sensitive dependence upon initial conditions. This is the result of an instability in phase space, which separates trajectories exponentially. Here, we demonstrate that this criterion should be refined. Despite their overall intrinsic instability, trajectories may be very strongly convergent in phase space over extremely long periods, as revealed by our investigation of a simple chaotic system (a realistic model for small bodies in a turbulent flow). We establish that this strong convergence is a multi-facetted phenomenon, in which the clustering is intense, widespread and balanced by lacunarity of other regions. Power laws, indicative of scale-free features, characterize the distribution of particles in the system. We use large-deviation and extreme-value statistics to explain the effect. Our results show that the interpretation of the ‘butterfly effect’ needs to be carefully qualified. We argue that the combination of mixing and clustering processes makes our specific model relevant to understanding the evolution of simple organisms. Lastly, this notion of convergent chaos, which implies the existence of conditions for which uncertainties are unexpectedly small, may also be relevant to the valuation of insurance and futures contracts.

  4. Late Cretaceous to Present evolution of the NW Africa peri-cratonic in the Africa-Eurasia plate convergence context

    Science.gov (United States)

    Ghorbal, B.; Bertotti, G.; Andriessen, P. A. M.

    2009-04-01

    Africa-Eurasia plate convergence is the main mechanism to explain topographic evolution and patterns of Tertiary vertical motions recorded around the entire Mediterranean and even further east. However, most of the studies are concentrated on the Eurasian side of the Mediterranean Realm. Along the NW Africa pericratonic zone (western Mediterranean side) extending longitudinally from the Anti-Atlas to the Rif Mountains, the highest topography is observed in the High Atlas intracontinental belt and in the Pan-African Anti-Atlas belt, and not in the youngest belt, the Rif. The combination of AFT and (U-Th)/He low-thermal dating, performed on pre-Cenozoic basement rocks along the Moroccan pericratonic transect (500km) yield ages ranging respectively between 90-9Ma and 65-7Ma, documenting vertical motions of subsidence and exhumation in between Late Cretaceous and Present. Time-Temperature models show that vertical movements are spatially zoned through Morocco, with the highest amplitude of vertical movements in the High Atlas (>4-5km) and more modest amounts in the Anti-Atlas and the Western Meseta (Meseta and the Anti-Atlas in addition to the Atlas and the Rif systems experienced Tertiary deformation. Two stages of folding are distinguished on the basis of low-thermal dating results along the pericratonic transect. The first is a lithospherical folding of ~500km in the Late Cretaceous (confirming that this process is a primary response to recently induced compressional stress fields) and the second is a crustal folding of ~100-150km wavelength in the Late Eocene that occurred independently to the mantle, requiring therefore the existence of a decoupling in between the base of the crust and the high mantle.

  5. Evolution of technology convergence networks in Korea: Characteristics of temporal changes in R&D according to institution type

    Science.gov (United States)

    Choi, Jae Young; Jeong, Seongkyoon

    2018-01-01

    This study investigates the temporal changes in development of technology convergence networks by institution type, i.e., public research institute (PRI), university and industry. Using the co-classification of technological domains of patents, we identified technology convergence of Korean patents, which were filed at Korea Intellectual Properties Office (KIPO) from 1997 to 2011. We conducted a network analysis at the technology level to search for the key technology fields and frequent instances of technology convergence. The results show that technology convergence networks have grown significantly in the recent period regardless of the institution type. While industries started to conspicuously engage in technology convergence in the late 1990s, universities or PRIs did not do so until the mid-2000s. This discrepancy in the phase of technology convergence is attributed to the temporal difference in R&D stage (e.g., basic research and commercial product development). Our findings imply that corporal and governmental R&D management decision on promising technology fields will be more effective if the decision makers carefully consider the type of R&D entity in analyzing technological landscapes. PMID:29420574

  6. The Convergence Years

    Science.gov (United States)

    Kolodzy, Janet; Grant, August E.; DeMars, Tony R.; Wilkinson, Jeffrey S.

    2014-01-01

    The emergence of the Internet, social media, and digital technologies in the twenty-first century accelerated an evolution in journalism and communication that fit under the broad term of convergence. That evolution changed the relationship between news producers and consumers. It broke down the geographical boundaries in defining our communities,…

  7. Evolution of anthozoan polyp retraction mechanisms: convergent functional morphology and evolutionary allometry of the marginal musculature in order Zoanthidea (Cnidaria: Anthozoa: Hexacorallia).

    Science.gov (United States)

    Swain, Timothy D; Schellinger, Jennifer L; Strimaitis, Anna M; Reuter, Kim E

    2015-06-30

    Retraction is among the most important basic behaviors of anthozoan Cnidaria polyps and is achieved through the coordinated contraction of at least six different muscle groups. Across the Anthozoa, these muscles range from unrecognizable atrophies to massive hypertrophies, producing a wide diversity of retraction abilities and functional morphologies. The marginal musculature is often the single largest component of the retraction mechanism and is composed of a diversity of muscular, attachment, and structural features. Although the arrangements of these features have defined the higher taxonomy of Zoanthidea for more than 100 years, a decade of inferring phylogenies from nucleotide sequences has demonstrated fundamental misconceptions of their evolution. Here we expand the diversity of known marginal muscle forms from two to at least ten basic states and reconstruct the evolution of its functional morphology across the most comprehensive molecular phylogeny available. We demonstrate that the evolution of these forms follows a series of transitions that are much more complex than previously hypothesized and converge on similar forms multiple times. Evolution of the marginal musculature and its attachment and support structures are partially scaled according to variation in polyp and muscle size, but also vary through evolutionary allometry. Although the retraction mechanisms are diverse and their evolutionary histories complex, their morphologies are largely reflective of the evolutionary relationships among Zoanthidea higher taxa and may offer a key feature for integrative systematics. The convergence on similar forms across multiple linages of Zoanthidea mirrors the evolution of the marginal musculature in another anthozoan order (Actiniaria). The marginal musculature varies through evolutionary allometry of functional morphologies in response to requirements for additional force and resistance, and the specific ecological and symbiotic functions of individual

  8. Tracking the Emergence of Host-Specific Simian Immunodeficiency Virus env and nef Populations Reveals nef Early Adaptation and Convergent Evolution in Brain of Naturally Progressing Rhesus Macaques.

    Science.gov (United States)

    Lamers, Susanna L; Nolan, David J; Rife, Brittany D; Fogel, Gary B; McGrath, Michael S; Burdo, Tricia H; Autissier, Patrick; Williams, Kenneth C; Goodenow, Maureen M; Salemi, Marco

    2015-08-01

    While a clear understanding of the events leading to successful establishment of host-specific viral populations and productive infection in the central nervous system (CNS) has not yet been reached, the simian immunodeficiency virus (SIV)-infected rhesus macaque provides a powerful model for the study of human immunodeficiency virus (HIV) intrahost evolution and neuropathogenesis. The evolution of the gp120 and nef genes, which encode two key proteins required for the establishment and maintenance of infection, was assessed in macaques that were intravenously inoculated with the same viral swarm and allowed to naturally progress to simian AIDS and potential SIV-associated encephalitis (SIVE). Longitudinal plasma samples and immune markers were monitored until terminal illness. Single-genome sequencing was employed to amplify full-length env through nef transcripts from plasma over time and from brain tissues at necropsy. nef sequences diverged from the founder virus faster than gp120 diverged. Host-specific sequence populations were detected in nef (~92 days) before they were detected in gp120 (~182 days). At necropsy, similar brain nef sequences were found in different macaques, indicating convergent evolution, while gp120 brain sequences remained largely host specific. Molecular clock and selection analyses showed weaker clock-like behavior and stronger selection pressure in nef than in gp120, with the strongest nef selection in the macaque with SIVE. Rapid nef diversification, occurring prior to gp120 diversification, indicates that early adaptation of nef in the new host is essential for successful infection. Moreover, the convergent evolution of nef sequences in the CNS suggests a significant role for nef in establishing neurotropic strains. The SIV-infected rhesus macaque model closely resembles HIV-1 immunopathogenesis, neuropathogenesis, and disease progression in humans. Macaques were intravenously infected with identical viral swarms to investigate

  9. Trade-Off or Convergence? The Role of Food Security in the Evolution of Food Discourse in Italy

    Science.gov (United States)

    Brunori, Gianluca; Malandrin, Vanessa; Rossi, Adanella

    2013-01-01

    In this paper we analyse the role that "food security" has played in the evolution of the food discourse in Italy, a country with a strong and internationally recognized food culture. We identify three phases of this evolution: in the first phase, from the end of the Second World War to the end of the 1980s, the "modernization"…

  10. Molecular Evidence for Convergence and Parallelism in Evolution of Complex Brains of Cephalopod Molluscs: Insights from Visual Systems

    OpenAIRE

    Yoshida, M. A.; Ogura, A.; Ikeo, K.; Shigeno, S.; Moritaki, T.; Winters, G. C.; Kohn, A. B.; Moroz, L.L.

    2015-01-01

    Coleoid cephalopods show remarkable evolutionary convergence with vertebrates in their neural organization, including (1) eyes and visual system with optic lobes, (2) specialized parts of the brain controlling learning and memory, such as vertical lobes, and (3) unique vasculature supporting such complexity of the central nervous system. We performed deep sequencing of eye transcriptomes of pygmy squids (Idiosepius paradoxus) and chambered nautiluses (Nautilus pompilius) to decipher the molec...

  11. Convergent evolution of health information management and health informatics: a perspective on the future of information professionals in health care.

    Science.gov (United States)

    Gibson, C J; Dixon, B E; Abrams, K

    2015-01-01

    Clearly defined boundaries are disappearing among the activities, sources, and uses of health care data and information managed by health information management (HIM) and health informatics (HI) professionals. Definitions of the professional domains and scopes of practice for HIM and HI are converging with the proliferation of information and communication technologies in health care settings. Convergence is changing both the roles that HIM and HI professionals serve in their organizations as well as the competencies necessary for training future professionals. Many of these changes suggest a blurring of roles and responsibilities with increasingly overlapping curricula, job descriptions, and research agendas. Blurred lines in a highly competitive market create confusion for students and employers. In this essay, we provide some perspective on the changing landscape and suggest a course for the future. First we review the evolving definitions of HIM and HI. We next compare the current domains and competencies, review the characteristics as well as the education and credentialing of both disciplines, and examine areas of convergence. Given the current state, we suggest a path forward to strengthen the contributions HIM and HI professionals and educators make to the evolving health care environment.

  12. Stochastic convergence

    CERN Document Server

    Lukacs, Eugene; Lukacs, E

    1975-01-01

    Stochastic Convergence, Second Edition covers the theoretical aspects of random power series dealing with convergence problems. This edition contains eight chapters and starts with an introduction to the basic concepts of stochastic convergence. The succeeding chapters deal with infinite sequences of random variables and their convergences, as well as the consideration of certain sets of random variables as a space. These topics are followed by discussions of the infinite series of random variables, specifically the lemmas of Borel-Cantelli and the zero-one laws. Other chapters evaluate the po

  13. Three-phase Interstellar Medium in Galaxies Resolving Evolution with Star Formation and Supernova Feedback (TIGRESS): Algorithms, Fiducial Model, and Convergence

    Science.gov (United States)

    Kim, Chang-Goo; Ostriker, Eve C.

    2017-09-01

    We introduce TIGRESS, a novel framework for multi-physics numerical simulations of the star-forming interstellar medium (ISM) implemented in the Athena MHD code. The algorithms of TIGRESS are designed to spatially and temporally resolve key physical features, including: (1) the gravitational collapse and ongoing accretion of gas that leads to star formation in clusters; (2) the explosions of supernovae (SNe), both near their progenitor birth sites and from runaway OB stars, with time delays relative to star formation determined by population synthesis; (3) explicit evolution of SN remnants prior to the onset of cooling, which leads to the creation of the hot ISM; (4) photoelectric heating of the warm and cold phases of the ISM that tracks the time-dependent ambient FUV field from the young cluster population; (5) large-scale galactic differential rotation, which leads to epicyclic motion and shears out overdense structures, limiting large-scale gravitational collapse; (6) accurate evolution of magnetic fields, which can be important for vertical support of the ISM disk as well as angular momentum transport. We present tests of the newly implemented physics modules, and demonstrate application of TIGRESS in a fiducial model representing the solar neighborhood environment. We use a resolution study to demonstrate convergence and evaluate the minimum resolution {{Δ }}x required to correctly recover several ISM properties, including the star formation rate, wind mass-loss rate, disk scale height, turbulent and Alfvénic velocity dispersions, and volume fractions of warm and hot phases. For the solar neighborhood model, all these ISM properties are converged at {{Δ }}x≤slant 8 {pc}.

  14. Morphological evolution of coexisting amphipod species pairs from sulfidic caves suggests competitive interactions and character displacement, but no environmental filtering and convergence.

    Science.gov (United States)

    Fišer, Cene; Luštrik, Roman; Sarbu, Serban; Flot, Jean-François; Trontelj, Peter

    2015-01-01

    Phenotypically similar species coexisting in extreme environments like sulfidic water are subject to two opposing eco-evolutionary processes: those favoring similarity of environment-specific traits, and those promoting differences of traits related to resource use. The former group of processes includes ecological filtering and convergent or parallel evolution, the latter competitive exclusion, character displacement and divergent evolution. We used a unique eco-evolutionary study system composed of two independent pairs of coexisting amphipod species (genus Niphargus) from the sulfidic caves Movile in Romania and Frasassi in Italy to study the relative contribution and interaction of both processes. We looked at the shape of the multifunctional ventral channel as a trait ostensibly related to oxygenation and sulfide detoxification, and at body size as a resource-related trait. Phylogenetic analysis suggests that the sulfidic caves were colonized separately by ancestors of each species. Species within pairs were more dissimilar in their morphology than expected according to a null model based on regional species pool. This might indicate competitive interactions shaping the morphology of these amphipod species. Moreover, our results suggest that the shape of the ventral channel is not subject to long-term convergent selection or to the process of environmental filtering, and as such probably does not play a role in sulfide tolerance. Nevertheless, the ancestral conditions reconstructed using the comparative method tended to be more similar than null-model expectations. This shift in patterns may reflect a temporal hierarchy of eco-evolutionary processes, in which initial environmental filtering became later on superseded by character displacement or other competition-driven divergent evolutionary processes.

  15. Convergent evolution of strigiform and caprimulgiform dark-activity is supported by phylogenetic analysis using the arylalkylamine N-acetyltransferase (Aanat) gene.

    Science.gov (United States)

    Fidler, Andrew E; Kuhn, Sylvia; Gwinner, Eberhard

    2004-12-01

    Alternative hypotheses propose the sister order of owls (Strigiformes) to be either day-active raptors (Falconiformes) or dark-active nightjars and allies (Caprimulgiformes). In an effort to identify molecular characters distinguishing between these hypotheses we examined a gene, arylalkylamine N-acetyltransferase (Aanat), potentially associated with the evolution of avian dark-activity. Partial Aanat coding sequences, and two introns, were obtained from the genomic DNA of 16 species: Strigiformes (four species), Falconiformes (four species), Caprimulgiformes (five species), with outgroups: Ciconiiformes (one species), Passeriformes (one species), and Apterygiformes (one species). Phylogenetic trees derived from aligned, evolutionarily conserved Aanat regions did not consistently recover clades corresponding to orders Strigiformes and Falconiformes but did place a caprimulgiform clade more distant from the strigiform and falconiform species than the latter two groups are to each other. This finding was supported by spectral analysis. The taxonomic distribution of seven intronic indels is consistent with the Aanat derived phylogenetic trees and supports conventional family-level groupings within both Strigiformes and Caprimulgiformes. The phylogenetic analyses also indicate that Caprimulgiformes is a polyphyletic grouping. In conclusion the data support, but do not conclusively prove, the proposal that Falconiformes is the sister order to Strigiformes and therefore, that the dark-activity characteristic of Strigiformes and Caprimulgiformes arose by convergent evolution.

  16. Functional and evolutionary anatomy of the African suckermouth catfishes (Siluriformes: Mochokidae): convergent evolution in Afrotropical and Neotropical faunas.

    Science.gov (United States)

    Geerinckx, Tom; De Kegel, Barbara

    2014-08-01

    Of those fishes scraping food off substrates and using head parts in substrate attachment for station-holding, the catfish families Loricariidae, Astroblepidae and Mochokidae display the most dramatically adapted morphologies. Loricariidae and Astroblepidae, living in the Neotropical freshwaters, exclusively contain suckermouth catfish species, and their anatomy and head kinematics have already been studied into detail. Among Mochokidae, living in the tropical freshwaters of Africa, only the chiloglanidine subfamily has a sucker mouth, and occupies similar niches in Africa as both Neotropical families do in South America. Having derived from relatively unrelated catfish ancestors, their anatomy is poorly known, and the nature of their scraping and station-holding capabilities is not known at all. This paper provides details on the chiloglanidine head anatomy and function (relating their anatomy to that of the non-suckermouth Mochokidae), and compares this Afrotropical suckermouth taxon with both Neotropical suckermouth families. It identifies both convergences and differing anatomical and kinematic solutions to the same key needs of food-scraping and station-holding suckermouth fishes. Chiloglanidine mochokids differ from both Neotropical families in having less mobile jaws, with an upper jaw assisting more in station-holding than in feeding. They share the highly mobile lower lip with both Neotropical taxa, although the configuration of the intermandibular/protractor hyoidei muscle system, changing the volume of the sucker-disc cavity, differs in all three taxa. Chiloglanidines have a single, posterior inflow opening into this cavity, whereas Loricariidae have two lateral openings, and Astroblepidae have none, using an opercular incurrent opening instead. The chiloglanidine buccal valve system consists of two passive valves, as in Astroblepidae. Although less diverse in number of genera and species, this Afrotropical suckermouth taxon possesses the anatomical and

  17. Convergent origins and rapid evolution of spliced leader trans-splicing in metazoa: insights from the ctenophora and hydrozoa.

    Science.gov (United States)

    Derelle, Romain; Momose, Tsuyoshi; Manuel, Michael; Da Silva, Corinne; Wincker, Patrick; Houliston, Evelyn

    2010-04-01

    Replacement of mRNA 5' UTR sequences by short sequences trans-spliced from specialized, noncoding, spliced leader (SL) RNAs is an enigmatic phenomenon, occurring in a set of distantly related animal groups including urochordates, nematodes, flatworms, and hydra, as well as in Euglenozoa and dinoflagellates. Whether SL trans-splicing has a common evolutionary origin and biological function among different organisms remains unclear. We have undertaken a systematic identification of SL exons in cDNA sequence data sets from non-bilaterian metazoan species and their closest unicellular relatives. SL exons were identified in ctenophores and in hydrozoan cnidarians, but not in other cnidarians, placozoans, or sponges, or in animal unicellular relatives. Mapping of SL absence/presence obtained from this and previous studies onto current phylogenetic trees favors an evolutionary scenario involving multiple origins for SLs during eumetazoan evolution rather than loss from a common ancestor. In both ctenophore and hydrozoan species, multiple SL sequences were identified, showing high sequence diversity. Detailed analysis of a large data set generated for the hydrozoan Clytia hemisphaerica revealed trans-splicing of given mRNAs by multiple alternative SLs. No evidence was found for a common identity of trans-spliced mRNAs between different hydrozoans. One feature found specifically to characterize SL-spliced mRNAs in hydrozoans, however, was a marked adenosine enrichment immediately 3' of the SL acceptor splice site. Our findings of high sequence divergence and apparently indiscriminate use of SLs in hydrozoans, along with recent findings in other taxa, indicate that SL genes have evolved rapidly in parallel in diverse animal groups, with constraint on SL exon sequence evolution being apparently rare.

  18. Multiple gene analyses of caligid copepods indicate that the reduction of a thoracic appendage in Pseudocaligus represents convergent evolution.

    Science.gov (United States)

    Freeman, Mark A; Anshary, Hilal; Ogawa, Kazuo

    2013-11-28

    The Caligidae is a family of parasitic copepods containing over 30 recognised genera. They are commercially important parasites as they cause disease in numerous finfish aquaculture facilities globally. Morphological features are used to distinguish between the genera and Pseudocaligus has traditionally been differentiated from Caligus solely by the presence of a much reduced form of the fourth thoracic leg. Currently there are numerous DNA sequences available for Caligus spp. but only the type species, Pseudocaligus brevipedis, has molecular data available, so systematic studies using molecular phylogenetic analyses have been limited. Three gene regions, SSU rDNA, 16S and CO1, for Pseudocaligus fugu from puffer fish from Japan and Pseudocaligus uniartus from rabbit fish from Indonesia are sequenced and molecular phylogenetic analyses performed in order to infer phylogenetic relationships between Pseudocaligus and other caligid copepods. The analysis revealed that there was no discrete grouping of Pseudocaligus spp. and that they had a polyphyletic distribution within Caligus taxa. Pseudocaligus fugu grouped with Caligus elongatus and contained a unique synapomorphy in the SSU rDNA region only seen in members of that clade. Pseudocaligus uniartus formed a well-supported group, in the SSU rDNA analyses, with a Caligus sp. that also infects rabbit fish, but was unresolved in the other analyses. Pseudocaligus brevipedis consistently and robustly grouped with Caligus curtus and C. centrodonti in all analyses. The majority of Lepeophtheirus spp. form a monophyletic sister group to the Caligus clade; however, L. natalensis is unresolved in all analyses and does not form part of the main Lepeophtheirus clade. These findings do not support the morphological-based distinction between Pseudocaligus and Caligus, suggesting that the reduced fourth leg is a feature that has evolved on multiple occasions throughout caligid evolution. Congruent molecular phylogenetic data support

  19. Convergent evolution of abrading flow obstacles: Insights from analogue modelling of fluvial bedrock abrasion by coarse bedload

    Science.gov (United States)

    Wilson, Andrew; Lavé, Jérôme

    2014-03-01

    Upstream-facing convex surfaces (UFCS) are formed by bedload abrasion in bedrock rivers and indicate the recent, significant action of bedload abrasion in causing channel incision. Beyond this, little is known of the dynamics of UFCS and the effect of substrate and bedload properties on rates and distribution of bedload abrasion for these bed roughness elements. Grain size populations from 1 to 8 cm (b-axis, in 1- or 2-cm bin widths) were used to bombard preshaped marble and limestone targets bolted to the base of an annular flume. The control of initial shape and lithology of the target and the erodent grain size and lithology were investigated by monitoring the evolution of the target form using laser scanning at predefined time intervals. Eleven experiment suites were carried out containing three initial target shapes constructed from two lithologies, four bedload (erodent) grain sizes of either granodiorites or limestone, or clear water flow. All 10 targets abraded by bedload evolved from their initial form into a steady state (time invariant) form, producing UFCSs. Steady state forms were closely similar for all targets despite different initial conditions. Bedload grain size has a strong control on this equilibrium form, related to the transit path of the grains when moving over the target, whilst initial target form has only a weak control. Steady state morphology is achieved more rapidly with harder erodent bedload particles and/or softer targets. Upstream-facing convex surface stoss sides were characterised by a brighter, sugary, granular appearance on the rock-forming grain scale. Increasing erodent grain size, for a fixed bedload mass, increased the bulk abrasion rate at fixed flow speed and discharge. No detectable erosion occurred for a limestone block in clear water flows under the same flow conditions, indicating solution and cavitation were insignificant mechanisms of erosion in this study. During the experiment suites, suspended load abrasion was

  20. Late Cenozoic evolution in the Pamir-Tian Shan convergence: New chronological constraints from the magnetostratigraphic record of the southwestern Tianshan foreland basin (Ulugqat area)

    Science.gov (United States)

    Qiao, Qingqing; Huang, Baochun; Biggin, Andrew J.; Piper, John D. A.

    2017-10-01

    The northeastern Pamir-Tian Shan convergence zone is a key region for understanding ongoing intracontinental mountain building. A detailed magnetostratigraphic study combined with color reflectance variations of continental sediments from the 1120 m-thick Sankeshu Section in the south west sector of the Tianshan Foreland Basin of western China yields important insights into the tectonic evolution of this zone. Correlation with the geomagnetic polarity time scale identifies deposition lasting from 16.7 to 2.6 Ma with a marked increase in sedimentation rate at 7 Ma. A further rapid increase occurred after 2.6 Ma with influx of the conglomeratic Xiyu Formation. Observed height-dependent changes of rock magnetic parameters (shape parameter T and AMS ellipsoid parameters) show that these sediments were influenced by weak deformation, with the sediments accumulated before 11 Ma recording a signature of compressive deformation from northward indentation by the Pamir. The succession of sedimentary events in the foreland basin is comparable to previous investigations of magnetostratigraphic and sedimentological analyses, and with thermochronology collectively showing that deformation in the Tian Shan region has been concentrated in Miocene and later times. The regional correlations resulting from these analyses show that sedimentary events correlate with the episodic nature of regional uplift with the latter inducing climatic changes that are in turn recorded in the sediment record.

  1. Fiscal Convergence in an Enlarged European Union

    Directory of Open Access Journals (Sweden)

    Georgeta VINTILĂ

    2014-02-01

    Full Text Available Taxation convergence in the European Union has always been a heatedly debated issue, and it has constantly resurfaced to the limelight as more and more fiscal directive proposals are being discussed. The current study is an analysis of the evolution of taxation convergence tendencies within the European Union in recent years, using sigma-convergence and cluster analysis. Our goal is to analyze the fiscal convergence trends in the context of European Union enlargement over the last two decades.

  2. Morphological convergence characterizes the evolution of Xanthophyceae (Heterokontophyta): evidence from nuclear SSU rDNA and plastidial rbcL genes.

    Science.gov (United States)

    Negrisolo, Enrico; Maistro, Silvia; Incarbone, Matteo; Moro, Isabella; Dalla Valle, Luisa; Broady, Paul A; Andreoli, Carlo

    2004-10-01

    Xanthophyceae are a group of heterokontophyte algae. Few molecular studies have investigated the evolutionary history and phylogenetic relationships of this class. We sequenced the nuclear-encoded SSU rDNA and chloroplast-encoded rbcL genes of several xanthophycean species from different orders, families, and genera. Neither SSU rDNA nor rbcL genes show intraspecific sequence variation and are good diagnostic markers for characterization of problematic species. New sequences, combined with those previously available, were used to create different multiple alignments. Analyses included sequences from 26 species of Xanthophyceae plus three Phaeothamniophyceae and two Phaeophyceae taxa used as outgroups. Phylogenetic analyses were performed according to Bayesian inference, maximum likelihood, and maximum parsimony methods. We explored effects produced on the phylogenetic outcomes by both taxon sampling as well as selected genes. Congruent results were obtained from analyses performed on single gene multiple alignments as well as on a data set including both SSU rDNA and rbcL sequences. Trees obtained in this study show that several currently recognized xanthophycean taxa do not form monophyletic groups. The order Mischococcales is paraphyletic, while Tribonematales and Botrydiales are polyphyletic even if evidence for the second order is not conclusive. Botrydiales and Vaucheriales, both including siphonous taxa, do not form a clade. The families Botrydiopsidaceae, Botryochloridaceae, and Pleurochloridaceae as well as the genera Botrydiopsis and Chlorellidium are polyphyletic. The Centritractaceae and the genus Bumilleriopsis also appear to be polyphyletic but their monophyly cannot be completely rejected with current evidence. Our results support morphological convergence at any taxonomic rank in the evolution of the Xanthophyceae. Finally, our phylogenetic analyses exclude an origin of the Xanthophyceae from a Vaucheria-like ancestor and favor a single early origin

  3. Skull osteology of the Eocene amphisbaenian Spathorhynchus fossorium (Reptilia, Squamata) suggests convergent evolution and reversals of fossorial adaptations in worm lizards.

    Science.gov (United States)

    Müller, Johannes; Hipsley, Christy A; Maisano, Jessica A

    2016-11-01

    The fossorial amphisbaenians, or worm lizards, are characterized by a suite of specialized characters in the skull and postcranium, however fossil evidence suggests that at least some of these shared derived traits evolved convergently. Unfortunately the lack of detailed knowledge of many fossil taxa has rendered a more precise interpretation difficult. Here we describe the cranial anatomy of the oldest-known well-preserved amphisbaenian, Spathorhynchus fossorium, from the Eocene Green River Formation, Wyoming, USA, using high-resolution X-ray computed tomography (HRXCT). This taxon possesses one of the most strongly reinforced crania known among amphisbaenians, with many dermal bones overlapping each other internally. In contrast to modern taxa, S. fossorium has a paired orbitosphenoid, lacks a true compound bone in the mandible, and possesses a fully enclosed orbital rim. The last feature represents a highly derived structure in that the jugal establishes contact with the frontal internally, reinforcing the posterior orbital margin. S. fossorium also possesses a strongly modified Vidian canal with a previously unknown connection to the ventral surface of the parabasisphenoid. Comparison with the closely related fossil taxon Dyticonastis rensbergeri reveals that these derived traits are also shared by the latter species and potentially represent synapopmorphies of an extinct Paleogene clade of amphisbaenians. The presence of a reinforced orbital rim suggests selection against the loss of a functional eye and indicates an ecology potentially different from modern taxa. Given the currently accepted phylogenetic position of Spathorhynchus and Dyticonastis, we predict that supposedly 'unique' cranial traits traditionally linked to fossoriality such as a fused orbitosphenoid and the reduction of the eye show a more complex character history than previously assumed, including both parallel evolution and reversals to superficially primitive conditions. © 2016

  4. A non-sense mutation in the putative anti-mutator gene ada/alkA of Mycobacterium tuberculosis and M. bovis isolates suggests convergent evolution

    Directory of Open Access Journals (Sweden)

    Gicquel Brigitte

    2007-05-01

    Full Text Available Abstract Background Previous studies have suggested that variations in DNA repair genes of W-Beijing strains may have led to transient mutator phenotypes which in turn may have contributed to host adaptation of this strain family. Single nucleotide polymorphism (SNP in the DNA repair gene mutT1 was identified in MDR-prone strains from the Central African Republic. A Mycobacteriumtuberculosis H37Rv mutant inactivated in two DNA repair genes, namely ada/alkA and ogt, was shown to display a hypermutator phenotype. We then looked for polymorphisms in these genes in Central African Republic strains (CAR. Results In this study, 55 MDR and 194 non-MDR strains were analyzed. Variations in DNA repair genes ada/alkA and ogt were identified. Among them, by comparison to M. tuberculosis published sequences, we found a non-sense variation in ada/alkA gene which was also observed in M. bovis AF2122 strain. SNPs that are present in the adjacent regions to the amber variation are different in M. bovis and in M. tuberculosis strain. Conclusion An Amber codon was found in the ada/alkA locus of clustered M. tuberculosis isolates and in M. bovis strain AF2122. This is likely due to convergent evolution because SNP differences between strains are incompatible with horizontal transfer of an entire gene. This suggests that such a variation may confer a selective advantage and be implicated in hypermutator phenotype expression, which in turn contributes to adaptation to environmental changes.

  5. Morphological convergence in 'river dolphin' skulls.

    Science.gov (United States)

    Page, Charlotte E; Cooper, Natalie

    2017-01-01

    Convergent evolution can provide insights into the predictability of, and constraints on, the evolution of biodiversity. One striking example of convergence is seen in the 'river dolphins'. The four dolphin genera that make up the 'river dolphins' ( Inia geoffrensis, Pontoporia blainvillei, Platanista gangetica and Lipotes vexillifer ) do not represent a single monophyletic group, despite being very similar in morphology. This has led many to using the 'river dolphins' as an example of convergent evolution. We investigate whether the skulls of the four 'river dolphin' genera are convergent when compared to other toothed dolphin taxa in addition to identifying convergent cranial and mandibular features. We use geometric morphometrics to uncover shape variation in the skulls of the 'river dolphins' and then apply a number of phylogenetic techniques to test for convergence. We find significant convergence in the skull morphology of the 'river dolphins'. The four genera seem to have evolved similar skull shapes, leading to a convergent morphotype characterised by elongation of skull features. The cause of this morphological convergence remains unclear. However, the features we uncover as convergent, in particular elongation of the rostrum, support hypotheses of shared feeding mode or diet and thus provide the foundation for future work into convergence within the Odontoceti.

  6. REAL CONVERGENCE AND INTEGRATION

    Directory of Open Access Journals (Sweden)

    Aurel Iancu

    2007-12-01

    Full Text Available The study is based on the critical observations that competitive market forces alone are not able to assure convergence with the developed countries. These observations are grounded on the results of the computation of the marginal rate of return to capital (which contradict the neoclassical model hypotheses, as well as on the real process of polarisation of the economic activities, taking place worldwide and in accordance with the law of competition. Unlike those who trust the perfect competitive market virtues, the EU’s economic policy is realistic as it is based on the harmonisation of the market forces with an economic policy based on the principle of cohesion, which supports, by means of economic levers, the less developed regions and member countries. This paper deals with the evolution of the EU cohesion funds, as well as with the results of convergence.

  7. Convergence of calls as animals form social bonds, active compensation for noisy communication channels, and the evolution of vocal learning in mammals.

    Science.gov (United States)

    Tyack, Peter L

    2008-08-01

    The classic evidence for vocal production learning involves imitation of novel, often anthropogenic sounds. Among mammals, this has been reported for dolphins, elephants, harbor seals, and humans. A broader taxonomic distribution has been reported for vocal convergence, where the acoustic properties of calls from different individuals converge when they are housed together in captivity or form social bonds in the wild. Vocal convergence has been demonstrated for animals as diverse as songbirds, parakeets, hummingbirds, bats, elephants, cetaceans, and primates. For most species, call convergence is thought to reflect a group-distinctive identifier, with shared calls reflecting and strengthening social bonds. A ubiquitous function for vocal production learning that is starting to receive attention involves modifying signals to improve communication in a noisy channel. Pooling data on vocal imitation, vocal convergence, and compensation for noise suggests a wider taxonomic distribution of vocal production learning among mammals than has been generally appreciated. The wide taxonomic distribution of this evidence for vocal production learning suggests that perhaps more of the neural underpinnings for vocal production learning are in place in mammals than is usually recognized. (c) 2008 APA, all rights reserved

  8. Extrasolar Planetary Complex Biosphere Organization as Exemplified

    Science.gov (United States)

    Heath, Martin; Williams, Darren; Doyle, Laurence

    Planetary habitability has usually been defined with reference to the physiological tolerances of human beings, or, in a more general sense, in terms of a modelled planet's ability to retain liquid water (essential for life as we know it) on its surface for a few Gyr. Another way of investigating habitability is with regard to the global mode of biosphere organization. Every combination of stellar composition and main sequence luminosity evolution, planetary characteristics and history, and biosphere organisation is unique, and will have its own specific inner and outer Habitable Zone radii. We illustrate this with modelled equilibrium partial pressures of CO_2. Although, as pointed out by previous workers, plants' CO_2 compensation points (where respiration exactly balances photosynthetic production) are just a few p.p.m. for some species, plants in the real world need to grow, repair tissue loss, reproduce and colonise new areas as they become available. This means that Earth-type forest ecosystems will require CO_2 levels comparable to those of the present day Earth. Reductions in equilibrium CO_2 with progressievely higher insolation, will define different inner margins for the Forest H.Z. with different axial obliquities and continential configurations.

  9. A Discourse on Tragedy in Traditional Yoruba Drama as Exemplified ...

    African Journals Online (AJOL)

    Many theatre scholars have come to accept the norm that only the Western form of tragedy as exemplified by Aristotle as the only tragedy but this has proven to be wrong owing to the fact that Arthur Miller theorized the tragedy of the common man. However, Soyinka the first African to theorize on tragedy has provided us with ...

  10. Morphological convergence in ‘river dolphin’ skulls

    OpenAIRE

    Page, Charlotte E.; Cooper, Natalie

    2017-01-01

    Convergent evolution can provide insights into the predictability of, and constraints on, the evolution of biodiversity. One striking example of convergence is seen in the ‘river dolphins’. The four dolphin genera that make up the ‘river dolphins’ (Inia geoffrensis, Pontoporia blainvillei, Platanista gangetica and Lipotes vexillifer) do not represent a single monophyletic group, despite being very similar in morphology. This has led many to using the ‘river dolphins’ as an example of converge...

  11. Evolutionary and Functional Analysis of Old World Primate TRIM5 Reveals the Ancient Emergence of Primate Lentiviruses and Convergent Evolution Targeting a Conserved Capsid Interface.

    Directory of Open Access Journals (Sweden)

    Kevin R McCarthy

    2015-08-01

    Full Text Available The widespread distribution of lentiviruses among African primates, and the lack of severe pathogenesis in many of these natural reservoirs, are taken as evidence for long-term co-evolution between the simian immunodeficiency viruses (SIVs and their primate hosts. Evidence for positive selection acting on antiviral restriction factors is consistent with virus-host interactions spanning millions of years of primate evolution. However, many restriction mechanisms are not virus-specific, and selection cannot be unambiguously attributed to any one type of virus. We hypothesized that the restriction factor TRIM5, because of its unique specificity for retrovirus capsids, should accumulate adaptive changes in a virus-specific fashion, and therefore, that phylogenetic reconstruction of TRIM5 evolution in African primates should reveal selection by lentiviruses closely related to modern SIVs. We analyzed complete TRIM5 coding sequences of 22 Old World primates and identified a tightly-spaced cluster of branch-specific adaptions appearing in the Cercopithecinae lineage after divergence from the Colobinae around 16 million years ago. Functional assays of both extant TRIM5 orthologs and reconstructed ancestral TRIM5 proteins revealed that this cluster of adaptations in TRIM5 specifically resulted in the ability to restrict Cercopithecine lentiviruses, but had no effect (positive or negative on restriction of other retroviruses, including lentiviruses of non-Cercopithecine primates. The correlation between lineage-specific adaptations and ability to restrict viruses endemic to the same hosts supports the hypothesis that lentiviruses closely related to modern SIVs were present in Africa and infecting the ancestors of Cercopithecine primates as far back as 16 million years ago, and provides insight into the evolution of TRIM5 specificity.

  12. Heat Flow Assesment From Bottom Simulating Reflector and Its Evolution Along The Southern Colombian Convergent Margin (1.5 To 3.5°n).

    Science.gov (United States)

    Marcaillou, Boris; Yves Collot, Jean; Spence, Georges; Wang, Kelin

    Several multichannel seismic profiles acquired during the Sisteur experiment, across the Colombia convergent margin, exhibit well identified Bottom Simulating Reflectors (BSRs). These BSRs, controlled by temperature and pressure conditions, coincide with the base of the gas hydrate stability field. Thus BSRs can be used to assess heat flow and hence the thermal regime of the Colombian margin. The BSRs show a negative polarity and extend to depths of 0.15 s below the seafloor (bsf) on the upper margin (~800 m of water depth) and to 0.78 s bsf at trench depths (3800 m). We assumed a purely conductive model to determine heat flow and its variation across the Colombian margin. The seafloor temperature was obtained from local CTD measurements and the thermal conductivity of the sediments was extrapolated from ODP Leg112 offshore Peru. BSRs are clearly identified along several dip and strike seismic lines. The heat flow values inferred from the BSR picks range between 30-40 mW/m2 along the middle and upper margin slopes, whereas these heat flow values increase to 80-100 mW/m2 close to the trench. Mapping these heat flow values exhibits important thermal variations along the Colombian margin. These variations could be accounted by the variating age of the crust from north to south, the different thicknesses of the trench sedimentary layer between the profiles or by the crustal structure complexity. The thermal modeling allowed us to obtain approximate temperatures along the top of the subducting Nazca plate. This late Miocene plate is considered as the main thermal source because the interpreted ophiolitic nature of the margin is believed to have negligible radiogenic heat production. The model integrates a 5 cm/year plate convergence rate and the margin structures as obtained from the SISTEUR multichannel seismic reflection and refraction data. The thermal parameters, in this model, were inferred from the rocks type within each layer. Temperatures at the top of the

  13. High-Throughput Sequencing of the Expressed Torafugu (Takifugu rubripes Antibody Sequences Distinguishes IgM and IgT Repertoires and Reveals Evidence of Convergent Evolution

    Directory of Open Access Journals (Sweden)

    Xi Fu

    2018-02-01

    Full Text Available B-cell antigen receptor (BCR or antibody diversity arises from somatic recombination of immunoglobulin (Ig gene segments and is concentrated within the Ig heavy (H chain complementarity-determining region 3 (CDR-H3. We performed high-throughput sequencing of the expressed antibody heavy-chain repertoire from adult torafugu. We found that torafugu use between 70 and 82% of all possible V (variable, D (diversity, and J (joining gene segment combinations and that they share a similar frequency distribution of these VDJ combinations. The CDR-H3 sequence repertoire observed in individuals is biased with the preferential use of a small number of VDJ, dominated by sequences containing inserted nucleotides. We uncovered the common CDR-H3 amino-acid (aa sequences shared by individuals. Common CDR-H3 sequences feature highly convergent nucleic-acid recombination compared with private ones. Finally, we observed differences in repertoires between IgM and IgT, including the unequal usage frequencies of V gene segment and the biased number of nucleotide insertion/deletion at VDJ junction regions that leads to distinct distributions of CDR-H3 lengths.

  14. Age, tectonic evolution and origin of the Aswa Shear Zone in Uganda: Activation of an oblique ramp during convergence in the East African Orogen

    Science.gov (United States)

    Saalmann, K.; Mänttäri, I.; Nyakecho, C.; Isabirye, E.

    2016-05-01

    Shear Zone activation is linked to underthrusting of the Congo Craton and coeval high-grade metamorphism and intense deformation in the orogen interior. During E-W convergence between ca. 690 and 650 Ma, the NE-dipping ASZ was activated as an oblique ramp leading to deflection of the transport direction and concentration of non-coaxial strain and sinistral shear along the shear zone system. During progressive convergence, between ca. 645 and 620 Ma, sinistral shearing along ASZ changed to ductile-brittle deformation mechanisms, while thrusting took place in Pan-African belts in eastern and western Uganda. Late-orogenic brittle sinistral reactivation of the ASZ can be regarded as the result of continent collision and closure of the Mozambique ocean further to the east, that potentially caused lateral escape manifested in NW-SE striking sinistral shear zones in Kenya and the southern Arabina-Nubian Shield between 620 and 570 Ma.

  15. Morphological convergence in ‘river dolphin’ skulls

    Directory of Open Access Journals (Sweden)

    Charlotte E. Page

    2017-11-01

    Full Text Available Convergent evolution can provide insights into the predictability of, and constraints on, the evolution of biodiversity. One striking example of convergence is seen in the ‘river dolphins’. The four dolphin genera that make up the ‘river dolphins’ (Inia geoffrensis, Pontoporia blainvillei, Platanista gangetica and Lipotes vexillifer do not represent a single monophyletic group, despite being very similar in morphology. This has led many to using the ‘river dolphins’ as an example of convergent evolution. We investigate whether the skulls of the four ‘river dolphin’ genera are convergent when compared to other toothed dolphin taxa in addition to identifying convergent cranial and mandibular features. We use geometric morphometrics to uncover shape variation in the skulls of the ‘river dolphins’ and then apply a number of phylogenetic techniques to test for convergence. We find significant convergence in the skull morphology of the ‘river dolphins’. The four genera seem to have evolved similar skull shapes, leading to a convergent morphotype characterised by elongation of skull features. The cause of this morphological convergence remains unclear. However, the features we uncover as convergent, in particular elongation of the rostrum, support hypotheses of shared feeding mode or diet and thus provide the foundation for future work into convergence within the Odontoceti.

  16. Morphological convergence in ‘river dolphin’ skulls

    Science.gov (United States)

    Cooper, Natalie

    2017-01-01

    Convergent evolution can provide insights into the predictability of, and constraints on, the evolution of biodiversity. One striking example of convergence is seen in the ‘river dolphins’. The four dolphin genera that make up the ‘river dolphins’ (Inia geoffrensis, Pontoporia blainvillei, Platanista gangetica and Lipotes vexillifer) do not represent a single monophyletic group, despite being very similar in morphology. This has led many to using the ‘river dolphins’ as an example of convergent evolution. We investigate whether the skulls of the four ‘river dolphin’ genera are convergent when compared to other toothed dolphin taxa in addition to identifying convergent cranial and mandibular features. We use geometric morphometrics to uncover shape variation in the skulls of the ‘river dolphins’ and then apply a number of phylogenetic techniques to test for convergence. We find significant convergence in the skull morphology of the ‘river dolphins’. The four genera seem to have evolved similar skull shapes, leading to a convergent morphotype characterised by elongation of skull features. The cause of this morphological convergence remains unclear. However, the features we uncover as convergent, in particular elongation of the rostrum, support hypotheses of shared feeding mode or diet and thus provide the foundation for future work into convergence within the Odontoceti. PMID:29177120

  17. New beaked whales from the late Miocene of Peru and evidence for convergent evolution in stem and crown Ziphiidae (Cetacea, Odontoceti

    Directory of Open Access Journals (Sweden)

    Giovanni Bianucci

    2016-09-01

    dentition; (2 an increase in the compactness and thickness of the rostral bones; (3 similar changes in facial morphology (e.g., elevation of the vertex; and (4 an increase of body size. We suggest that these trends may be linked to a convergent ecological shift to deep diving and suction feeding.

  18. New beaked whales from the late Miocene of Peru and evidence for convergent evolution in stem and crown Ziphiidae (Cetacea, Odontoceti).

    Science.gov (United States)

    Bianucci, Giovanni; Di Celma, Claudio; Urbina, Mario; Lambert, Olivier

    2016-01-01

    ) an increase in the compactness and thickness of the rostral bones; (3) similar changes in facial morphology (e.g., elevation of the vertex); and (4) an increase of body size. We suggest that these trends may be linked to a convergent ecological shift to deep diving and suction feeding.

  19. Molecular archaeology of Flaviviridae untranslated regions: duplicated RNA structures in the replication enhancer of flaviviruses and pestiviruses emerged via convergent evolution.

    Science.gov (United States)

    Gritsun, Dmitri J; Jones, Ian M; Gould, Ernest A; Gritsun, Tamara S

    2014-01-01

    RNA secondary structures in the 3'untranslated regions (3'UTR) of the viruses of the family Flaviviridae, previously identified as essential (promoters) or beneficial (enhancers) for replication, have been analysed. Duplicated enhancer elements are revealed as a global feature in the evolution of the 3'UTR of distantly related viruses within the genera Flavivirus and Pestivirus. For the flaviviruses, duplicated structures occur in the 3'UTR of all four distantly related ecological virus subgroups (tick-borne, mosquito-borne, no known vector and insect-specific flaviviruses (ISFV). RNA structural differences distinguish tick-borne flaviviruses with discrete pathogenetic characteristics. For Aedes- and Culex-associated ISFV, secondary RNA structures with different conformations display numerous short ssRNA direct repeats, exposed as loops and bulges. Long quadruplicate regions comprise almost the entire 3'UTR of Culex-associated ISFV. Extended duplicated sequence and associated RNA structures were also discovered in the 3'UTR of pestiviruses. In both the Flavivirus and Pestivirus genera, duplicated RNA structures were localized to the enhancer regions of the 3'UTR suggesting an adaptive role predominantly in wild-type viruses. We propose sequence reiteration might act as a scaffold for dimerization of proteins involved in assembly of viral replicase complexes. Numerous nucleotide repeats exposed as loops/bulges might also interfere with host immune responses acting as a molecular sponge to sequester key host proteins or microRNAs.

  20. Association of the OCA2 polymorphism His615Arg with melanin content in east Asian populations: further evidence of convergent evolution of skin pigmentation.

    Directory of Open Access Journals (Sweden)

    Melissa Edwards

    2010-03-01

    Full Text Available The last decade has witnessed important advances in our understanding of the genetics of pigmentation in European populations, but very little is known about the genes involved in skin pigmentation variation in East Asian populations. Here, we present the results of a study evaluating the association of 10 Single Nucleotide Polymorphisms (SNPs located within 5 pigmentation candidate genes (OCA2, DCT, ADAM17, ADAMTS20, and TYRP1 with skin pigmentation measured quantitatively in a sample of individuals of East Asian ancestry living in Canada. We show that the non-synonymous polymorphism rs1800414 (His615Arg located within the OCA2 gene is significantly associated with skin pigmentation in this sample. We replicated this result in an independent sample of Chinese individuals of Han ancestry. This polymorphism is characterized by a derived allele that is present at a high frequency in East Asian populations, but is absent in other population groups. In both samples, individuals with the derived G allele, which codes for the amino acid arginine, show lower melanin levels than those with the ancestral A allele, which codes for the amino acid histidine. An analysis of this non-synonymous polymorphism using several programs to predict potential functional effects provides additional support for the role of this SNP in skin pigmentation variation in East Asian populations. Our results are consistent with previous research indicating that evolution to lightly-pigmented skin occurred, at least in part, independently in Europe and East Asia.

  1. Evolution

    Science.gov (United States)

    Peter, Ulmschneider

    When we are looking for intelligent life outside the Earth, there is a fundamental question: Assuming that life has formed on an extraterrestrial planet, will it also develop toward intelligence? As this is hotly debated, we will now describe the development of life on Earth in more detail in order to show that there are good reasons why evolution should culminate in intelligent beings.

  2. Converged Registries Solution (CRS)

    Data.gov (United States)

    Department of Veterans Affairs — The Converged Registries platform is a hardware and software architecture designed to host individual patient registries and eliminate duplicative development effort...

  3. CONVERGENCE OF TECHNOLOGIES

    Directory of Open Access Journals (Sweden)

    R. Siriram

    2012-01-01

    Full Text Available

    ENGLISH ABSTRACT: Technology is a catalyst for competitive advantage. However, it is how technology is used that leads to a firm’s improved performance. In this article, an investigative framework is constructed to understand better what strategically drives new technology adoption. The strategic drivers include technology and business strategy alignment, better technology planning and selection of new technologies, the effects on a firm’s culture and climate, links to a firm’s organisational and environmental evolution, and benefits through convergence and collaboration. Using an investigative framework, it is shown how the strategic drivers link to improve a firm’s performance, producing competitive advantage. The investigative framework is tested using structural equation modelling. Various hypotheses are formed, and recommendations for further research are made.

    AFRIKAANSE OPSOMMING: Tegnologie is ‘n katalisator vir mededingende voordeel. Dit is egter hoe tegnologie aangewend word wat aanleiding gee tot ‘n onderneming se verbeterde prestasie. In hierdie artikel word ‘n ondersoekende raamwerk gekonstrueer om insig te kry in dit wat die aanvaarding van nuwe tegnologie strategies dryf. Die strategiese dryfvere sluit in die belyning van tegnologie en ondernemingstrategie, beter tegnologiebeplanning en seleksie van nuwe tegnologieë, die effek op ‘n onderneming se kultuur en klimaat, koppeling na ‘n onderneming se organisatoriese en omgewingsevolusie, en voordele verkry deur konvergensie en samewerking. Deur ‘n ondersoekende raamwerk te gebruik, word daar getoon dat die strategiese dryfvere koppel om ‘n onderneming se prestasie te verbeter en sodoende ‘n mededingende voordeel te skep. Die raamwerk word getoets en hipoteses geformuleer waarna aanbevelings oor verdere navorsing aan die hand gedoen word.

  4. Mosaic convergence of rodent dentitions.

    Directory of Open Access Journals (Sweden)

    Vincent Lazzari

    Full Text Available BACKGROUND: Understanding mechanisms responsible for changes in tooth morphology in the course of evolution is an area of investigation common to both paleontology and developmental biology. Detailed analyses of molar tooth crown shape have shown frequent homoplasia in mammalian evolution, which requires accurate investigation of the evolutionary pathways provided by the fossil record. The necessity of preservation of an effective occlusion has been hypothesized to functionally constrain crown morphological changes and to also facilitate convergent evolution. The Muroidea superfamily constitutes a relevant model for the study of molar crown diversification because it encompasses one third of the extant mammalian biodiversity. METHODOLOGY/PRINCIPAL FINDINGS: Combined microwear and 3D-topographic analyses performed on fossil and extant muroid molars allow for a first quantification of the relationships between changes in crown morphology and functionality of occlusion. Based on an abundant fossil record and on a well resolved phylogeny, our results show that the most derived functional condition associates longitudinal chewing and non interlocking of cusps. This condition has been reached at least 7 times within muroids via two main types of evolutionary pathways each respecting functional continuity. In the first type, the flattening of tooth crown which induces the removal of cusp interlocking occurs before the rotation of the chewing movement. In the second type however, flattening is subsequent to rotation of the chewing movement which can be associated with certain changes in cusp morphology. CONCLUSION/SIGNIFICANCE: The reverse orders of the changes involved in these different pathways reveal a mosaic evolution of mammalian dentition in which direction of chewing and crown shape seem to be partly decoupled. Either can change in respect to strong functional constraints affecting occlusion which thereby limit the number of the possible

  5. Evolutionary Convergence on Sleep Loss in Cavefish Populations

    National Research Council Canada - National Science Library

    Duboué, Erik R; Keene, Alex C; Borowsky, Richard L

    2011-01-01

    .... The characin fish, Astyanax mexicanus, has eyed surface and numerous blind cave populations. The cave populations are largely independent in their origins, and the species is ideal for studying the genetic bases of convergent evolution...

  6. Convergent Aeronautics Solutions Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Convergent Aeronautics Solutions (CAS) Project uses short-duration activities to establish early-stage concept and technology feasibility for high-potential...

  7. Fixed mobile convergence handbook

    CERN Document Server

    Ahson, Syed A

    2010-01-01

    From basic concepts to future directions, this handbook provides technical information on all aspects of fixed-mobile convergence (FMC). The book examines such topics as integrated management architecture, business trends and strategic implications for service providers, personal area networks, mobile controlled handover methods, SIP-based session mobility, and supervisory and notification aggregator service. Case studies are used to illustrate technical and systematic implementation of unified and rationalized internet access by fixed-mobile network convergence. The text examines the technolo

  8. The crucial role of the Pls1 tetraspanin during ascospore germination in Podospora anserina provides an example of the convergent evolution of morphogenetic processes in fungal plant pathogens and saprobes.

    Science.gov (United States)

    Lambou, Karine; Malagnac, Fabienne; Barbisan, Crystel; Tharreau, Didier; Lebrun, Marc-Henri; Silar, Philippe

    2008-10-01

    Pls1 tetraspanins were shown for some pathogenic fungi to be essential for appressorium-mediated penetration into their host plants. We show here that Podospora anserina, a saprobic fungus lacking appressorium, contains PaPls1, a gene orthologous to known PLS1 genes. Inactivation of PaPls1 demonstrates that this gene is specifically required for the germination of ascospores in P. anserina. These ascospores are heavily melanized cells that germinate under inducing conditions through a specific pore. On the contrary, MgPLS1, which fully complements a DeltaPaPls1 ascospore germination defect, has no role in the germination of Magnaporthe grisea nonmelanized ascospores but is required for the formation of the penetration peg at the pore of its melanized appressorium. P. anserina mutants with mutation of PaNox2, which encodes the NADPH oxidase of the NOX2 family, display the same ascospore-specific germination defect as the DeltaPaPls1 mutant. Both mutant phenotypes are suppressed by the inhibition of melanin biosynthesis, suggesting that they are involved in the same cellular process required for the germination of P. anserina melanized ascospores. The analysis of the distribution of PLS1 and NOX2 genes in fungal genomes shows that they are either both present or both absent. These results indicate that the germination of P. anserina ascospores and the formation of the M. grisea appressorium penetration peg use the same molecular machinery that includes Pls1 and Nox2. This machinery is specifically required for the emergence of polarized hyphae from reinforced structures such as appressoria and ascospores. Its recurrent recruitment during fungal evolution may account for some of the morphogenetic convergence observed in fungi.

  9. IT-BT convergence technology

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2012-12-15

    This book explains IT-BT convergence technology as the future technology, which includes a prolog, easy IT-BT convergence technology that has infinite potentials for new value, policy of IT-BT convergence technology showing the potential of smart Korea, IT-BT convergence opening happy future, for the new future of IT powerful nation Korea with IT-BT convergence technology and an epilogue. This book reveals the conception, policy, performance and future of IT-BT convergence technology.

  10. Convergence of estuarine channels

    Science.gov (United States)

    Dronkers, Job

    2017-07-01

    Tide-dominated coastal plain estuaries have typically up-estuary convergent tidal channels. Analysis of estuarine characteristics indicates a dependence of the convergence length on relative tidal amplitude, relative intertidal area and river flow velocity. In order to explain these relationships we investigate a condition for continuity of net sediment transport throughout the estuary, corresponding to morphodynamic equilibrium. We show, by using an analytical solution of the tidal equations, that this condition is equivalent to a condition on the convergence length. This condition is evaluated for 21 estuaries in different regions of the world. It appears that the convergence length determined in this way can explain observed convergence lengths for the considered set of estuaries. The dependence of the convergence length on different estuarine characteristics is analysed by solving the fully coupled hydro-morphodynamic equations. We show that this dependence limits the range of variation of the tidal velocity amplitude. The analysis provides insight in the morphological response of estuaries to human interventions. The condition can easily be evaluated to yield an estimate of this response.

  11. Contrasting patterns of adaptive sequence convergence among echolocating mammals.

    Science.gov (United States)

    Lambert, Matthew J; Nevue, Alexander A; Portfors, Christine V

    2017-03-20

    Several recent studies have described genes demonstrating adaptive sequence convergence between echolocating bats and dolphin, suggesting that common selective pressures can induce common molecular changes, even in distantly related species. However, in the case of the auditory genes Otoferlin (Otof), Cadherin 23 (Cdh23) and Protocadherin 15 (Pcdh15), the reported sequence convergence was supported only by incongruent gene and species trees and counts of convergent substitutions. Therefore, it remains unclear whether echolocating bats and dolphin really do demonstrate evidence of adaptive sequence convergence, or whether there is simply a high level of random background convergence in these genes. To address this question, we estimated the number of convergent and divergent amino acid substitutions along all independent branches of a sufficiently deep phylogeny containing between 22 and 32 mammals for each gene, and compared convergence between the two proposed suborders of bat, Yangochiroptera and Yinpterochiroptera, and dolphin. We find no support for convergence between bats and dolphin in the gene Pcdh15. For the gene Otof we report minimal evidence for convergent evolution only between the Yinpterochiroptera and dolphin. Cdh23 displayed a high level of convergence between dolphin and the Yinpterochiroptera. In addition, dolphin and certain members of the Yangochiroptera that emit high frequency echolocation calls shared several unique convergent substitutions. These results indicate that the convergent evolution of Cdh23 was likely driven by selection for hearing above a certain frequency threshold. Moreover, the contrasting patterns of convergence between the two bat suborders and dolphin in all auditory genes studied thus far suggest echolocation may have evolved independently in the Yinpterochiroptera and Yangochiroptera. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Ecomorphological convergence of cave communities.

    Science.gov (United States)

    Trontelj, Peter; Blejec, Andrej; Fišer, Cene

    2012-12-01

    Extreme selective environments are commonly believed to funnel evolution toward a few predictable outcomes. Caves are well-known extreme environments with characteristically adapted faunas that are similar in appearance, physiology, and behavior all over the world, even if not closely related. Morphological diversity between closely related cave species has been explained by difference in time since colonization and different ecological influence from the surface. Here, we tested a more classical hypothesis: morphological diversity is niche-based, and different morphologies reflect properties of microhabitats within caves. We analyzed seven communities with altogether 30 species of the subterranean amphipod (crustacean) genus Niphargus using multivariate morphometrics, multinomial logit models cross-validation, and phylogenetic reconstruction. Species clustered into four distinct ecomorph classes-small pore, cave stream, cave lake, and lake giants-associated with specific cave microhabitats and of multiple independent phylogenetic origins. Traits commonly regarded as adaptations to caves, such as antenna length, were shown to be related to microhabitat parameters, such as flow velocity. These results demonstrate that under the selection pressure of extreme environment, the ecomorphological structure of communities can converge. Thus, morphological diversity does not result from adaptive response to temporal and ecological gradients, but from fine-level niche partitioning. © 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.

  13. Ecomorphological convergence in planktivorous surgeonfishes

    KAUST Repository

    Friedman, S. T.

    2016-01-26

    © 2016 European Society For Evolutionary Biology. Morphological convergence plays a central role in the study of evolution. Often induced by shared ecological specialization, homoplasy hints at underlying selective pressures and adaptive constraints that deterministically shape the diversification of life. Although midwater zooplanktivory has arisen in adult surgeonfishes (family Acanthuridae) at least four independent times, it represents a clearly specialized state, requiring the capacity to swiftly swim in midwater locating and sucking small prey items. Whereas this diet has commonly been associated with specific functional adaptations in fishes, acanthurids present an interesting case study as all nonplanktivorous species feed by grazing on benthic algae and detritus, requiring a vastly different functional morphology that emphasizes biting behaviours. We examined the feeding morphology in 30 acanthurid species and, combined with a pre-existing phylogenetic tree, compared the fit of evolutionary models across two diet regimes: zooplanktivores and nonzooplanktivorous grazers. Accounting for phylogenetic relationships, the best-fitting model indicates that zooplanktivorous species are converging on a separate adaptive peak from their grazing relatives. Driving this bimodal landscape, zooplanktivorous acanthurids tend to develop a slender body, reduced facial features, smaller teeth and weakened jaw adductor muscles. However, despite these phenotypic changes, model fitting suggests that lineages have not yet reached the adaptive peak associated with plankton feeding even though some transitions appear to be over 10 million years old. These findings demonstrate that the selective demands of pelagic feeding promote repeated - albeit very gradual - ecomorphological convergence within surgeonfishes, while allowing local divergences between closely related species, contributing to the overall diversity of the clade. Journal of Evolutionary Biology

  14. Convergent beam neutron crystallography

    Science.gov (United States)

    Gibson, Walter M.; Schultz, Arthur J.; Richardson, James W.; Carpenter, John M.; Mildner, David F. R.; Chen-Mayer, Heather H.; Miller, M. E.; Maxey, E.; Prask, Henry J.; Gnaeupel-Herold, Thomas H.; Youngman, Russell

    2004-01-01

    Applications of neutron diffraction for small samples (small fiducial areas are limited by the available neutron flux density. Recent demonstrations of convergent beam electron and x-ray diffraction and focusing of cold (λ>1 Å) neutrons suggest the possibility to use convergent beam neutron diffraction for small sample crystallography. We have carried out a systematic study of diffraction of both monoenergetic and broad bandwidth neutrons at the NIST Research Reactor and at the Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory. Combining convergent beams with time-of-flight Laue diffraction is particularly attractive for high efficiency small sample diffraction studies. We have studied single crystal and powder diffraction of neutrons with convergence angles as large as 15° and have observed diffracted peak intensity gains greater than 20. The convergent beam method (CBM) shows promise for crystallography on small samples of small to medium size molecules (potentially even for proteins), ultra-high pressure samples, and for mapping of strain and texture distributions in larger samples.

  15. Convergence from divergence

    Science.gov (United States)

    Costin, Ovidiu; Dunne, Gerald V.

    2018-01-01

    We show how to convert divergent series, which typically occur in many applications in physics, into rapidly convergent inverse factorial series. This can be interpreted physically as a novel resummation of perturbative series. Being convergent, these new series allow rigorous extrapolation from an asymptotic region with a large parameter, to the opposite region where the parameter is small. We illustrate the method with various physical examples, and discuss how these convergent series relate to standard methods such as Borel summation, and also how they incorporate the physical Stokes phenomenon. We comment on the relation of these results to Dyson’s physical argument for the divergence of perturbation theory. This approach also leads naturally to a wide class of relations between bosonic and fermionic partition functions, and Klein–Gordon and Dirac determinants.

  16. Convergent Filter Bases

    Directory of Open Access Journals (Sweden)

    Coghetto Roland

    2015-09-01

    Full Text Available We are inspired by the work of Henri Cartan [16], Bourbaki [10] (TG. I Filtres and Claude Wagschal [34]. We define the base of filter, image filter, convergent filter bases, limit filter and the filter base of tails (fr: filtre des sections.

  17. Convergence of Networks

    DEFF Research Database (Denmark)

    Prasad, Ramjee; Ruggieri, Marina

    2008-01-01

    The paper focuses on the revolutionary changes that could characterise the future of networks. Those changes involve many aspects in the conceivement and exploitation of networks: architecture, services, technologies and modeling. The convergence of wired and wireless technologies along with the ...

  18. Summable series and convergence factors

    CERN Document Server

    Moore, Charles N

    1938-01-01

    Fairly early in the development of the theory of summability of divergent series, the concept of convergence factors was recognized as of fundamental importance in the subject. One of the pioneers in this field was C. N. Moore, the author of the book under review.... Moore classifies convergence factors into two types. In type I he places the factors which have only the property that they preserve convergence for a convergent series or produce convergence for a summable series. In type II he places the factors which not only maintain or produce convergence but have the additional property that

  19. Morphological convergence in ‘river dolphin’ skulls: a disparate grouping justified

    OpenAIRE

    Page, Charlotte E; Cooper, Natalie

    2017-01-01

    Convergent evolution can provide insights into the predictability of, and constraints on, the evolution of biodiversity. One striking example of convergence is seen in the ‘river dolphins’. The four dolphin genera that make up the ‘river dolphins’ (Inia geoffrensis, Pontoporia blainvillei, Platanista gangetica and Lipotes vexillifer) do not represent a monophyletic group, despite being very similar in morphology. This has led many to using the ‘river dolphins’ as an example of convergent evol...

  20. The Convergent Learning Space:

    DEFF Research Database (Denmark)

    Kjærgaard, Hanne Wacher; Kjeldsen, Lars Peter; Asmussen, Jørgen Bering

    This paper describes the concept of “The Convergent Learning Space” as it is being explored in an ongoing action research project carried out at undergraduate level in select bachelor programs at a Danish University College. The background nature, design, and beginning of this work in progress......, trajectories of participation etc. calls for new action and new pedagogies by teachers in order to secure alignment between students’ worlds and expectations and aims and plans of the teacher. Action research methods are being used to define and test the constituents and variables of the convergent learning...... is described as well as the theoretical construct and hypotheses surrounding the emergence of the concept in technology-rich classrooms, where students bring their own devices and involve their personal learning spaces and networks. The need for new ways of approaching concepts like choice, learning resources...

  1. The Convergent Learning Space

    DEFF Research Database (Denmark)

    Kjeldsen, Lars Peter; Kjærgaard, Hanne Wacher

    The concept of the Convergent Learning Space has been hypothesized and explored in an ongoing action research project carried out at undergraduate level in select bachelor programs at a Danish University College, where classrooms are technology rich and students bring their own devices. The changes...... networks are still more prominently expected by students. Against this backdrop, an action research project has worked with the definition and testing of the hypothesized constituents of the Convergent Learning Space and how it challenges our traditional conceptions of learning spaces. The article...... describes this pilot study involving teachers in conscious, documented reflection on methods, approaches, and procedures conducive to learning processes in this new learning space. As a perspective, the article briefly outlines an intervention study aimed at investigating how students benefit from...

  2. Multiplier convergent series and uniform convergence of mapping ...

    Indian Academy of Sciences (India)

    j=1 Aj (xj ) converges uniformly with respect to (xj ) in any M ∈ M. Moreover, in the last section we give some applications for mapping series. 2. The space of multiplier convergent series. First, we define the frame property of complex sequence set λ, which is important in studying multiplier convergent series. DEFINITION 2.1.

  3. IT Convergence and Security 2012

    CERN Document Server

    Chung, Kyung-Yong

    2013-01-01

    The proceedings approaches the subject matter with problems in technical convergence and convergences of security technology. This approach is new because we look at new issues that arise from techniques converging. The general scope of the proceedings content is convergence security and the latest information technology. The intended readership are societies, enterprises, and research institutes, and intended content level is mid- to highly educated personals. The most important features and benefits of the proceedings are the introduction of the most recent information technology and its related ideas, applications and problems related to technology convergence, and its case studies and finally an introduction of converging existing security techniques through convergence security. Overall, through the proceedings, authors will be able to understand the most state of the art information strategies and technologies of convergence security.

  4. Convergence of Romanian accounting regulations with IFRS. A longitudinal analysis

    Directory of Open Access Journals (Sweden)

    Ioana PĂLĂRIE

    2016-06-01

    Full Text Available In this paper we analyse the evolution in the level of convergence of the Romanian accounting regulations with IFRS in the last decade. We focus our study on the accounting topics covered by IAS16, IAS17, IAS 41 and SIC15. We find that in 2005 the regulations exhibit a good level of convergence for property, plant and equipment, a medium level of convergence for lease accounting and divergence for accounting for the agricultural activity. The overall convergence level improved over time for all the topics analysed. These results indicate that the companies with dual reporting may incur lower costs in applying IFRS. Moreover, the national regulations offer the opportunity for a higher level of comparability in Romania of the financial statements prepared under IFRS with those prepared under national regulations. However, we underline that the institutional factors (such as the tax influence over accounting might negatively affect the convergence of practices.

  5. Digital Convergence – Smart Devices

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Digital Convergence – Smart Devices. More and more devices become cheap one-chip components. Different devices are joined to form new multi-purpose devices. Devices and applications converge to form digital personal tools. Behind digital convergence is the ...

  6. Development of synchronous VHL syndrome tumors reveals contingencies and constraints to tumor evolution

    DEFF Research Database (Denmark)

    Fisher, Rosalie; Horswell, Stuart; Rowan, Andrew

    2014-01-01

    with a germline VHL mutation. We report that tumors arising in this context are clonally independent and harbour distinct secondary events exemplified by loss of chromosome 3p, despite an identical genetic background and tissue microenvironment. We propose that divergent mutational and copy number anomalies......Background : Genomic analysis of multi-focal renal cell carcinomas from an individual with a germline VHL mutation offers a unique opportunity to study tumor evolution. Results : We perform whole exome sequencing on four clear cell renal cell carcinomas removed from both kidneys of a patient...... are contingent upon the nature of 3p loss of heterozygosity occurring early in tumorigenesis. However, despite distinct 3p events, genomic, proteomic and immunohistochemical analyses reveal evidence for convergence upon the PI3K-AKT-mTOR signaling pathway. Four germline tumors in this young patient...

  7. Invited paper: A Review of Thresheld Convergence

    Directory of Open Access Journals (Sweden)

    Stephen Chen

    2015-07-01

    Full Text Available A multi-modal search space can be defined as having multiple attraction basins – each basin has a single local optimum which is reached from all points in that basin when greedy local search is used. Optimization in multi-modal search spaces can then be viewed as a two-phase process. The first phase is exploration in which the most promising attraction basin is identified. The second phase is exploitation in which the best solution (i.e. the local optimum within the previously identified attraction basin is attained. The goal of thresheld convergence is to improve the performance of search techniques during the first phase of exploration. The effectiveness of thresheld convergence has been demonstrated through applications to existing metaheuristics such as particle swarm optimization and differential evolution, and through the development of novel metaheuristics such as minimum population search and leaders and followers.

  8. Local Convergence and Radius of Convergence for Modified Newton Method

    Directory of Open Access Journals (Sweden)

    Măruşter Ştefan

    2017-12-01

    Full Text Available We investigate the local convergence of modified Newton method, i.e., the classical Newton method in which the derivative is periodically re-evaluated. Based on the convergence properties of Picard iteration for demicontractive mappings, we give an algorithm to estimate the local radius of convergence for considered method. Numerical experiments show that the proposed algorithm gives estimated radii which are very close to or even equal with the best ones.

  9. DOES THE MAASTRICHT CONVERGENCE CRITERIA WORK?

    Directory of Open Access Journals (Sweden)

    Karsai Zoltán-Krisztián

    2012-12-01

    Full Text Available During its 13 year history, the euro area experienced the most severe economic downturn in the late 2000s as a result of the 2007 financial-economic crisis stemming from the US banking sector. The crisis in the monetary union, besides posting a significant economic and social cost, revealed several weaknesses not just of the currency block as a whole, but also of its constituting members, which were masked by the prosperous economic environment characteristic for the 2000s. These conditions have put to the test the solidarity among the euro zone members, or in other words the existence of the currency block. One important problem of the currency block is the lack of harmony between the fiscal and economic policies of the member states, creating several and occasionally very divergent parts of the currency block. The aim of this research is to enhance the Maastricht convergence criteria’s and the Stability and Growth Pact’s role as a monitoring mechanism, allowing them to become more informative tools for the policy makers. For this, based on the relevant literature, we propose new potential explanatory variables which could enhance the role of the Maastricht convergence criteria and the Stability and Growth Pact. Some of the studied variables, like indebtedness of the private sector, capital flow compared to the size of the economy, government revenue compared to total public debt and current account balance help in enforcing the nominal convergence, while others (real labour productivity contribute to the real convergence. The explanatory power of the proposed variables are investigated in the case of France, Germany, Greece, Ireland, Italy, Portugal and Spain for the period comprised between 2000Q1-2011Q4. Results of the research show that with the exception of government revenue compared to total public debt, all proposed variables have significant explanatory power regarding the evolution of the state of the economy in all

  10. Homology, convergence and parallelism.

    Science.gov (United States)

    Ghiselin, Michael T

    2016-01-05

    Homology is a relation of correspondence between parts of parts of larger wholes. It is used when tracking objects of interest through space and time and in the context of explanatory historical narratives. Homologues can be traced through a genealogical nexus back to a common ancestral precursor. Homology being a transitive relation, homologues remain homologous however much they may come to differ. Analogy is a relationship of correspondence between parts of members of classes having no relationship of common ancestry. Although homology is often treated as an alternative to convergence, the latter is not a kind of correspondence: rather, it is one of a class of processes that also includes divergence and parallelism. These often give rise to misleading appearances (homoplasies). Parallelism can be particularly hard to detect, especially when not accompanied by divergences in some parts of the body. © 2015 The Author(s).

  11. Medialogy - convergence and transdisciplinarity

    DEFF Research Database (Denmark)

    Nordahl, Rolf

    2007-01-01

    Art and design have many qualities which intuitively by society are appreciated. But on daily basis they are also assessed and evaluated. Some communities also share common understandings that norms, standards, conventions evolve, both from artistic desire as well as from more physical needs...... for changes in society, developments in taste etc.  However, it certainly seems fair to say, that available technology makes a great difference to the development of any art form or practice. With the up rise of new educations such as Medialogy, new aspects of convergence and different forms...... of interdisciplinarity and transdisciplinarity is a pre-requisite for both researchers and students. In this talk we will demonstrate our approach through concrete examples of student productions and projects. We will also display the pedagogical method (problem based learning), that enables students to bridge gaps...

  12. The EU's Convergence Dilemma

    Directory of Open Access Journals (Sweden)

    Notermans Ton

    2015-02-01

    Full Text Available As economic stagnation continues to mark the EU in the fifth year of the euro zone crisis, political support for integration is waning. The European Parliament elections of 2014 returned a hitherto unparalleled number of Eurosceptic MEPs, with EU-critical parties becoming the largest ones in several Member States. Much of this Euroscepticism is driven by economic polarisation between core and peripheral countries. While an increasing number of voters in the northwestern creditor countries resent having to foot the bill for what they consider economic mismanagement in the periphery, voters in peripheral countries increasingly rebel against what they deem to be an economically catastrophic Diktat from Germany and its allies. Continued political support for European integration will hinge on successful income convergence in the EU but the current dilemma is that such policies might not be politically feasible. Periods of rapid convergence would seem to suggest that success depends on two main policy strategies. First, a monetary policy that promotes credit for productive purposes, leaves inflation control to other instruments, and employs selective credit rationing to prevent asset booms. Second, a vertical industrial policy prioritising selected industrial sectors. The first policy conflicts with the present framework of euro zone monetary policy, but that framework was only installed in the first place because many peripheral countries were desperately in search of an external constraint on domestic distributional conflict. Industrial policies, in turn, require a sufficient degree of state autonomy from business elites in order to be effective, but it is highly questionable whether most states in the EU possess such autonomy. Though there are, as yet hesitant, signs of a reorientation of both monetary and cohesion policy in the EU, the question of the institutional and political preconditions for their successful implementation has been largely

  13. De-internationalization: Evolution of the Concept

    DEFF Research Database (Denmark)

    Turcan, Romeo V.

    In this paper I discuss the evolution of the concept of de-internationalization. I look at the evolution of de-internationalization via empirical and theoretical lenses. I draw on recent empirical evidence to exemplify the evolution of what, how, why, who, where, when of de-internationalization. ...... then discuss the evolution of theoretical developments of the concept employing a number theory building strategies. I conclude the paper by mapping theoretical landscape of de-internationalization phenomenon suggesting future research directions.......In this paper I discuss the evolution of the concept of de-internationalization. I look at the evolution of de-internationalization via empirical and theoretical lenses. I draw on recent empirical evidence to exemplify the evolution of what, how, why, who, where, when of de-internationalization. I...

  14. Applying Convergent Immunity to Innovative Vaccines Targeting Staphylococcus aureus

    Directory of Open Access Journals (Sweden)

    Michael R Yeaman

    2014-09-01

    Full Text Available Recent perspectives forecast a new paradigm for future 3rd generation vaccines based on commonalities found in diverse pathogens or convergent immune defenses to such pathogens. For Staphylococcus aureus, recurring infections and a limited success of vaccines containing S. aureus antigens imply that native antigens induce immune responses insufficient for optimal efficacy. These perspectives exemplify the need to apply novel vaccine strategies to high priority pathogens. One such approach can be termed convergent immunity, where antigens from non-target organisms that contain epitope homologues found in the target organism are applied in vaccines. This approach aims to evoke atypical immune defenses via synergistic processes that 1 afford protective efficacy; 2 target an epitope from one organism that contributes to protective immunity against another; 3 cross-protect against multiple pathogens occupying a common anatomic or immunologic niche; and/or 4 overcome immune subversion or avoidance strategies of target pathogens. Thus, convergent immunity has a potential to promote protective efficacy not usually elicited by native antigens from a target pathogen. Variations of this concept have been mainstays in the history of viral and bacterial vaccine development. A more far-reaching example is the pre–clinical evidence that specific fungal antigens can induce cross-kingdom protection against bacterial pathogens. This trans-kingdom protection has been demonstrated in preclinical studies of the recombinant Candida albicans agglutinin-like sequence 3 protein (rAls3 where it was shown that a vaccine containing rAls3 provides homologous protection against C. albicans, heterologous protection against several other Candida species, and convergent protection against several strains of S. aureus. Convergent immunity reflects an intriguing new approach to designing and developing vaccine antigens and is considered here in the context of vaccines to target

  15. Applying Convergent Immunity to Innovative Vaccines Targeting Staphylococcus aureus

    Science.gov (United States)

    Yeaman, Michael R.; Filler, Scott G.; Schmidt, Clint S.; Ibrahim, Ashraf S.; Edwards, John E.; Hennessey, John P.

    2014-01-01

    Recent perspectives forecast a new paradigm for future “third generation” vaccines based on commonalities found in diverse pathogens or convergent immune defenses to such pathogens. For Staphylococcus aureus, recurring infections and a limited success of vaccines containing S. aureus antigens imply that native antigens induce immune responses insufficient for optimal efficacy. These perspectives exemplify the need to apply novel vaccine strategies to high-priority pathogens. One such approach can be termed convergent immunity, where antigens from non-target organisms that contain epitope homologs found in the target organism are applied in vaccines. This approach aims to evoke atypical immune defenses via synergistic processes that (1) afford protective efficacy; (2) target an epitope from one organism that contributes to protective immunity against another; (3) cross-protect against multiple pathogens occupying a common anatomic or immunological niche; and/or (4) overcome immune subversion or avoidance strategies of target pathogens. Thus, convergent immunity has a potential to promote protective efficacy not usually elicited by native antigens from a target pathogen. Variations of this concept have been mainstays in the history of viral and bacterial vaccine development. A more far-reaching example is the pre-clinical evidence that specific fungal antigens can induce cross-kingdom protection against bacterial pathogens. This trans-kingdom protection has been demonstrated in pre-clinical studies of the recombinant Candida albicans agglutinin-like sequence 3 protein (rAls3) where it was shown that a vaccine containing rAls3 provides homologous protection against C. albicans, heterologous protection against several other Candida species, and convergent protection against several strains of S. aureus. Convergent immunity reflects an intriguing new approach to designing and developing vaccine antigens and is considered here in the context of vaccines to target S

  16. Independent Molecular Basis of Convergent Highland Adaptation in Maize

    Science.gov (United States)

    Takuno, Shohei; Ralph, Peter; Swarts, Kelly; Elshire, Rob J.; Glaubitz, Jeffrey C.; Buckler, Edward S.; Hufford, Matthew B.; Ross-Ibarra, Jeffrey

    2015-01-01

    Convergent evolution is the independent evolution of similar traits in different species or lineages of the same species; this often is a result of adaptation to similar environments, a process referred to as convergent adaptation. We investigate here the molecular basis of convergent adaptation in maize to highland climates in Mesoamerica and South America, using genome-wide SNP data. Taking advantage of archaeological data on the arrival of maize to the highlands, we infer demographic models for both populations, identifying evidence of a strong bottleneck and rapid expansion in South America. We use these models to then identify loci showing an excess of differentiation as a means of identifying putative targets of natural selection and compare our results to expectations from recently developed theory on convergent adaptation. Consistent with predictions across a wide parameter space, we see limited evidence for convergent evolution at the nucleotide level in spite of strong similarities in overall phenotypes. Instead, we show that selection appears to have predominantly acted on standing genetic variation and that introgression from wild teosinte populations appears to have played a role in highland adaptation in Mexican maize. PMID:26078279

  17. Convergence of generalized eigenfunction expansions

    Directory of Open Access Journals (Sweden)

    Mayumi Sakata

    2007-05-01

    Full Text Available We present a simplified theory of generalized eigenfunction expansions for a commuting family of bounded operators and with finitely many unbounded operators. We also study the convergence of these expansions, giving an abstract type of uniform convergence result, and illustrate the theory by giving two examples: The Fourier transform on Hecke operators, and the Laplacian operators in hyperbolic spaces.

  18. Gas/electricity convergence: role of marketers

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, K.G. [Powerex Corp., Inc., Youngwood, PA (United States)

    1997-04-01

    The role of marketers in the convergence of the gas and electricity industry was presented. Topics of discussion included types of convergence, such as wholesale price convergence, BTU convergence, energy information systems service convergence, and corporate convergence. Also discussed was a review of technical, economic, political and regulatory barriers to convergence. Implications for customers, regulators and vertically integrated utilities and trade associations were also assessed.

  19. Subterranean mammals show convergent regression in ocular genes and enhancers, along with adaptation to tunneling

    Science.gov (United States)

    Partha, Raghavendran; Chauhan, Bharesh K; Ferreira, Zelia; Robinson, Joseph D; Lathrop, Kira; Nischal, Ken K

    2017-01-01

    The underground environment imposes unique demands on life that have led subterranean species to evolve specialized traits, many of which evolved convergently. We studied convergence in evolutionary rate in subterranean mammals in order to associate phenotypic evolution with specific genetic regions. We identified a strong excess of vision- and skin-related genes that changed at accelerated rates in the subterranean environment due to relaxed constraint and adaptive evolution. We also demonstrate that ocular-specific transcriptional enhancers were convergently accelerated, whereas enhancers active outside the eye were not. Furthermore, several uncharacterized genes and regulatory sequences demonstrated convergence and thus constitute novel candidate sequences for congenital ocular disorders. The strong evidence of convergence in these species indicates that evolution in this environment is recurrent and predictable and can be used to gain insights into phenotype–genotype relationships. PMID:29035697

  20. Character Journaling through Social Networks: Exemplifying Tenets of the New Literacy Studies

    Science.gov (United States)

    White, John Wesley; Hungerford-Kresser, Holly

    2014-01-01

    Countering reactionary attempts to ban social media from schools is a strong research based rationale for bringing social media into the literacy classroom. When used as a medium to explore literature--or more specifically for interactive character journaling--this medium exemplifies how meaning is created by individuals' interactions with…

  1. Late Miocene-Pleistocene evolution of India-Eurasia convergence partitioning between the Bhutan Himalaya and the Shillong Plateau: New evidences from foreland basin deposits along the Dungsam Chu section, eastern Bhutan

    Science.gov (United States)

    Coutand, Isabelle; Barrier, Laurie; Govin, Gwladys; Grujic, Djordje; Hoorn, Carina; Dupont-Nivet, Guillaume; Najman, Yani

    2016-12-01

    The Shillong Plateau is a unique basement-cored uplift in the foreland of the eastern Himalaya that accommodates part of the India-Eurasia convergence since the late Miocene. It was uplifted in the late Pliocene to 1600 m, potentially inducing regional climatic perturbations by orographically condensing part of the Indian Summer Monsoon (ISM) precipitations along its southern flank. As such, the eastern Himalaya-Shillong Plateau-ISM is suited to investigate effects of tectonics, climate, and erosion in a mountain range-broken foreland system. This study focuses on a 2200 m thick sedimentary section of the Siwalik Group strategically located in the lee of the Shillong Plateau along the Dungsam Chu at the front of the eastern Bhutan Himalaya. We have performed magnetostratigraphy constrained by vitrinite reflectance and detrital apatite fission track dating, combined with sedimentological and palynological analyses. We show that (1) the section was deposited between 7 and 1 Ma in a marginal marine deltaic transitioning into continental environment after 5 Ma, (2) depositional environments and paleoclimate were humid with no major change during the depositional period indicating that the orographic effect of the Shillong Plateau had an unexpected limited impact on the paleoclimate of the Bhutanese foothills, and (3) the diminution of the flexural subsidence in the basin and/or of the detrital input from the range is attributable to a slowdown of the displacement rates along the Main Boundary Thrust in eastern Bhutan during the latest Miocene-Pleistocene, in response to increasing partitioning of the India-Eurasia convergence into the active faults bounding the Shillong Plateau.

  2. Sufficient condition on the fractional integral for the convergence of a function.

    Science.gov (United States)

    Duarte-Mermoud, Manuel A; Aguila-Camacho, Norelys; Gallegos, Javier A

    2013-01-01

    A sufficient condition on the fractional integral of the absolute value of a function is given in this paper, which allows to assure the convergence of the function to zero. This result can be useful to assure the convergence of a function when it is hard to know its exact evolution, but conditions on its fractional integral can be stated.

  3. European Integration through Economic Convergence

    Directory of Open Access Journals (Sweden)

    Savoiu Gheorghe

    2016-05-01

    Full Text Available The thematic topicality of the main issues of European integration through convergence, in the context subsequent to financial-inspired global recession, is relevant through both the ever more extended international impact of the inertiality of a number of integration processes, and the specific developments of convergence in the Eurozone or the European Monetary Union (EMU. The regionally structured system of the European economy, approached aggregatively from the micro-economic to the macro-economic level, like the physical system or molecularly investigated system, from economic transactions, as a major milestone, to the complexity of the transactions tissue or flows, or activities, similar to biological systems, is permanently faced with various specific disturbing factors. The European Union (EU has historically evolved in an alternative manner, sometimes divergently or towards differentiation through separation, and sometimes convergently or coherently towards unity, fusion, integrity, evincing divergence or convergence trends, with the latter eventually becoming prevalent in the contemporary world.

  4. On convergence completeness in symmetric spaces | Moshokoa ...

    African Journals Online (AJOL)

    convergence complete symmetric space. As applications of convergence completeness, we present some fixed point results for self-maps defined on a symmetric space. Keywords: completeness; convergence completeness; fixed points; metric ...

  5. Periodic Convergences: Dance and Computers

    OpenAIRE

    deLahunta, Scott

    2002-01-01

    Published in German and English, this chapter is one of deLahunta's major outputs to emerge from a group of related research outputs, concerning "dance and technology". In it he explores the history of the convergence between dance and computers from the 1960s to the 1990s, arguing that this convergence has been periodic, involving particular artists at particular times, rather than producing a genre of work (as others have speculated). As the mainstream of contemporary dance evolved alongsid...

  6. Hausdorff convergence of Julia sets

    NARCIS (Netherlands)

    Krauskopf, B; Kriete, H

    1999-01-01

    Consider a sequence {g(d)}(d is an element of N) converging uniformly on compact sets to g, where g and g(d) are meromorphic functions on C. We show that the Julia sets J(g(d)) converge to the Julia set J(g) in the Hausdorff metric, if the Fatou set F(g) is the union of basins of attracting periodic

  7. Convergence palsy secondary to amoxicillin.

    Science.gov (United States)

    Pérez-Roca, F; Alfaro Juárez, A; Sánchez Merino, C; Navarro Mingorance, A

    2016-12-01

    We present the case of an 11-year-old boy with acute diplopia in near vision secondary to transient convergence palsy, possibly in relation to amoxicillin. Convergence palsy is an uncommon eye disorder. The causes are reviewed, and amoxicilin is identified as presumptive etiologic agent. This is the first case reported. Copyright © 2016 Sociedad Española de Oftalmología. Publicado por Elsevier España, S.L.U. All rights reserved.

  8. Intercontinental community convergence of ecology and morphology in desert lizards.

    Science.gov (United States)

    Melville, Jane; Harmon, Luke J; Losos, Jonathan B

    2006-03-07

    Evolutionary ecologists have long debated the extent to which communities in similar environments but different geographic regions exhibit convergence. On the one hand, if species' adaptations and community structure are determined by environmental features, convergence would be expected. However, if historical contingencies have long-lasting effects convergence would be unlikely. Most studies to date have emphasized the differences between communities in similar environments and little quantitative evidence for convergence exists. The application of comparative phylogenetic methods to ecological studies provides an opportunity to further investigate hypotheses of convergence. We compared the evolutionary patterns of structural ecology and morphology of 42 species of iguanian lizards from deserts of Australia and North America. Using a comparative approach, we found that evolutionary convergence of ecology and morphology occurs both in overall, community-wide patterns and in terms of pairs of highly similar intercontinental pairs of species. This result indicates that in these desert lizards, deterministic adaptive evolution shapes community patterns and overrides the historical contingencies unique to particular lineages.

  9. Globalization and Contemporary Fertility Convergence.

    Science.gov (United States)

    Hendi, Arun S

    2017-09-01

    The rise of the global network of nation-states has precipitated social transformations throughout the world. This article examines the role of political and economic globalization in driving fertility convergence across countries between 1965 and 2009. While past research has typically conceptualized fertility change as a country-level process, this study instead employs a theoretical and methodological framework that examines differences in fertility between pairs of countries over time. Convergence in fertility between pairs of countries is hypothesized to result from increased cross-country connectedness and cross-national transmission of fertility-related schemas. I investigate the impact of various cross-country ties, including ties through bilateral trade, intergovernmental organizations, and regional trade blocs, on fertility convergence. I find that globalization acts as a form of social interaction to produce fertility convergence. There is significant heterogeneity in the effects of different cross-country ties. In particular, trade with rich model countries, joint participation in the UN and UNESCO, and joining a free trade agreement all contribute to fertility convergence between countries. Whereas the prevailing focus in fertility research has been on factors producing fertility declines, this analysis highlights specific mechanisms-trade and connectedness through organizations-leading to greater similarity in fertility across countries. Globalization is a process that propels the spread of culturally laden goods and schemas impinging on fertility, which in turn produces fertility convergence.

  10. Exploring Media Convergence: Evidence from Italy

    Directory of Open Access Journals (Sweden)

    Debora Bettiga

    2013-12-01

    Full Text Available The evolution of media and devices is enabling the ubiquitous and multi-device access to media and information, so that a media mutual contamination is in play. New forms of user interactions with media, in which different devices are used simultaneously in different contexts, have emerged. These new interactions are significantly impacting on users’ attitudes towards the media and their way of searching and generating content. Such a change, called “media convergence”, has a strong potential impact on marketing and communication processes, but as yet has not been deeply analysed in the literature. This paper presents the outcomes of several studies aimed at exploring media convergence on the demand-side to advance possible implications for marketers and managers.

  11. Convergence of complex cognitive abilities in cetaceans and primates.

    Science.gov (United States)

    Marino, Lori

    2002-01-01

    What examples of convergence in higher-level complex cognitive characteristics exist in the animal kingdom? In this paper I will provide evidence that convergent intelligence has occurred in two distantly related mammalian taxa. One of these is the order Cetacea (dolphins, whales and porpoises) and the other is our own order Primates, and in particular the suborder anthropoid primates (monkeys, apes, and humans). Despite a deep evolutionary divergence, adaptation to physically dissimilar environments, and very different neuroanatomical organization, some primates and cetaceans show striking convergence in social behavior, artificial 'language' comprehension, and self-recognition ability. Taken together, these findings have important implications for understanding the generality and specificity of those processes that underlie cognition in different species and the nature of the evolution of intelligence. Copyright 2002 S. Karger AG, Basel

  12. Digital Convergence and Content Regulation

    Directory of Open Access Journals (Sweden)

    Michael John Starks

    2014-12-01

    Full Text Available Broadcasting, Press and Internet journalism systems of distribution are converging: the same infrastructure can deliver all three historically separate services. Reception devices mirror this: the Connected TV, the tablet and the smart phone overlap in their functionality. Service overlaps are evident too, with broadcasters providing online and on-demand services and newspapers developing electronic versions. Does this mean that media regulation policies must converge too?My argument is that they should, though only where historically different communications are now fulfilling a similar function, e.g. broadcaster online services and electronic versions of newspapers. Convergence requires a degree of harmonisation and, to this end, I advocate a review of UK broadcasting's 'due impartiality' requirement and of the UK's application of the public service concept. I also argue for independent self-regulation (rather than state-based regulation of non-public-service broadcasting journalism.

  13. Lattice-valued convergence ring and its uniform convergence structure

    African Journals Online (AJOL)

    Considering L a frame, we introduce the notion of stratified L-neighborhood topological ring, produce some characterization theorems including its Luniformizability. With the help of the notions of stratified convergence structures attributed to Gunther J¨ager [10], we introduce and study various subcategories of stratified ...

  14. Cultura da Convergência

    Directory of Open Access Journals (Sweden)

    Rogério Christofoletti

    2008-12-01

    Full Text Available Três idéias já seriam suficientes para que a leitura de “Cultura da Convergência”, de Henry Jenkins, interessasse a jornalistas e pesquisadores da área: a convergência midiática como um processo cultural; o fortalecimento de uma economia afetiva que orienta consumidores de bens simbólicos e criadores midiáticos; a expansão de formas narrativas transmidiáticas.

  15. Identical skin toxins by convergent molecular adaptation in frogs.

    Science.gov (United States)

    Roelants, Kim; Fry, Bryan G; Norman, Janette A; Clynen, Elke; Schoofs, Liliane; Bossuyt, Franky

    2010-01-26

    The Tree of Life is rife with adaptive convergences at all scales and biological levels of complexity. However, natural selection is not likely to result in the independent evolution of identical gene products. Here we report such a striking example of evolutionary convergence in the toxic skin secretions of two distantly related frog lineages. Caeruleins are important decapeptides in pharmacological and clinical research [1] and are commonly believed to represent a single evolutionary class of peptides [2-4]. Instead, our phylogenetic analyses combining transcriptome and genome data reveal that independently evolved precursor genes encode identical caeruleins in Xenopus and Litoria frogs. The former arose by duplication from the cholecystokinin (cck) gene, whereas the latter was derived from the gastrin gene. These hormone genes that are involved in many physiological processes diverged early in vertebrate evolution, after a segmental duplication during the Cambrian period. Besides implicating convergent mutations of the peptide-encoding sequence, recurrent caerulein origins entail parallel shifts of expression from the gut-brain axis to skin secretory glands. These results highlight extreme structural convergence in anciently diverged genes as an evolutionary mechanism through which recurrent adaptation is attained across large phylogenetic distances. Copyright 2010 Elsevier Ltd. All rights reserved.

  16. International Convergence on Geoscience Cyberinfrastructure

    Science.gov (United States)

    Allison, M. L.; Atkinson, R.; Arctur, D. K.; Cox, S.; Jackson, I.; Nativi, S.; Wyborn, L. A.

    2012-04-01

    There is growing international consensus on addressing the challenges to cyber(e)-infrastructure for the geosciences. These challenges include: Creating common standards and protocols; Engaging the vast number of distributed data resources; Establishing practices for recognition of and respect for intellectual property; Developing simple data and resource discovery and access systems; Building mechanisms to encourage development of web service tools and workflows for data analysis; Brokering the diverse disciplinary service buses; Creating sustainable business models for maintenance and evolution of information resources; Integrating the data management life-cycle into the practice of science. Efforts around the world are converging towards de facto creation of an integrated global digital data network for the geosciences based on common standards and protocols for data discovery and access, and a shared vision of distributed, web-based, open source interoperable data access and integration. Commonalities include use of Open Geospatial Consortium (OGC) and ISO specifications and standardized data interchange mechanisms. For multidisciplinarity, mediation, adaptation, and profiling services have been successfully introduced to leverage the geosciences standards which are commonly used by the different geoscience communities -introducing a brokering approach which extends the basic SOA archetype. Principal challenges are less technical than cultural, social, and organizational. Before we can make data interoperable, we must make people interoperable. These challenges are being met by increased coordination of development activities (technical, organizational, social) among leaders and practitioners in national and international efforts across the geosciences to foster commonalities across disparate networks. In doing so, we will 1) leverage and share resources, and developments, 2) facilitate and enhance emerging technical and structural advances, 3) promote

  17. Convergence results for a class of abstract continuous descent methods

    Directory of Open Access Journals (Sweden)

    Sergiu Aizicovici

    2004-03-01

    Full Text Available We study continuous descent methods for the minimization of Lipschitzian functions defined on a general Banach space. We establish convergence theorems for those methods which are generated by approximate solutions to evolution equations governed by regular vector fields. Since the complement of the set of regular vector fields is $sigma$-porous, we conclude that our results apply to most vector fields in the sense of Baire's categories.

  18. Digital Convergence and Content Regulation

    NARCIS (Netherlands)

    Starks, Michael John

    2014-01-01

    abstractBroadcasting, Press and Internet journalism systems of distribution are converging: the same infrastructure can deliver all three historically separate services. Reception devices mirror this: the Connected TV, the tablet and the smart phone overlap in their functionality. Service overlaps

  19. Converge, Version 3.0

    Directory of Open Access Journals (Sweden)

    Lotfi Tadj

    1993-01-01

    Full Text Available Although intended for college teachers/students, Converge presents a feature that may interest all scientists: it allows an easy export of graphic files to most known word processors, specifically to the ℙ, Version 2.1, a powerful WYSIWYG mathematical word processor.

  20. At the Eve of Convergence?

    DEFF Research Database (Denmark)

    Henriksen, Lars Skov; Zimmer, Annette; Smith, Steven Rathgeb

    . Specifically, we will investigate whether and to what extent social services and health care in these three countries are affected by current changes. With a special focus on nonprofit organizations, we will particularly address the question whether a trend towards convergence of the very different welfare...

  1. Converging Information and Communication Systems

    DEFF Research Database (Denmark)

    Øst, Alexander

    2003-01-01

    in the future to have - significant importance to the process and consequences of the convergence. The project focuses on the appliances, i.e. the TV sets, the computers and their peripheral equipment. It also takes into account the infrastructure and signals, which contain and deliver the information...

  2. Privatization, convergence, and institutional autonomy

    NARCIS (Netherlands)

    Rooijen, van M.

    2011-01-01

    Some of the trends incoming for 2011 – greater institutional autonomy, public/private convergence, entrepreneurial management, civic engagement – suggest innovation for hard times, with socio-economic and political rationales increasingly driving borderless developments. Others – open learning and

  3. System Convergence in Transport Modelling

    DEFF Research Database (Denmark)

    Rich, Jeppe; Nielsen, Otto Anker; Cantarella, Guilio E.

    2010-01-01

    -of-successive-averages (MSA) have been proposed. Convergence of the MSA under fairly weak regularity conditions was shown in Robbins and Monro (1951). The iteration between demand and assignment ? the external equilibrium ? are in many models either decoupled or follow a very simple iteration pattern. However, as demand...

  4. The probability of genetic parallelism and convergence in natural populations.

    Science.gov (United States)

    Conte, Gina L; Arnegard, Matthew E; Peichel, Catherine L; Schluter, Dolph

    2012-12-22

    Genomic and genetic methods allow investigation of how frequently the same genes are used by different populations during adaptive evolution, yielding insights into the predictability of evolution at the genetic level. We estimated the probability of gene reuse in parallel and convergent phenotypic evolution in nature using data from published studies. The estimates are surprisingly high, with mean probabilities of 0.32 for genetic mapping studies and 0.55 for candidate gene studies. The probability declines with increasing age of the common ancestor of compared taxa, from about 0.8 for young nodes to 0.1-0.4 for the oldest nodes in our study. Probability of gene reuse is higher when populations begin from the same ancestor (genetic parallelism) than when they begin from divergent ancestors (genetic convergence). Our estimates are broadly consistent with genomic estimates of gene reuse during repeated adaptation to similar environments, but most genomic studies lack data on phenotypic traits affected. Frequent reuse of the same genes during repeated phenotypic evolution suggests that strong biases and constraints affect adaptive evolution, resulting in changes at a relatively small subset of available genes. Declines in the probability of gene reuse with increasing age suggest that these biases diverge with time.

  5. Aggregate Morphology Evolution by Sintering: Number & Diameter of Primary Particles.

    Science.gov (United States)

    Eggersdorfer, Max L; Kadau, Dirk; Herrmann, Hans J; Pratsinis, Sotiris E

    2012-04-01

    The structure of fractal-like agglomerates (physically-bonded) and aggregates (chemically- or sinter-bonded) is important in aerosol synthesis of nanoparticles, and in monitoring combustion emissions and atmospheric particles. It influences also particle mobility, scattering, and eventually performance of nanocomposites, suspensions and devices made with such particles. Here, aggregate sintering by viscous flow of amorphous materials (silica, polymers) and grain boundary diffusion of crystalline ceramics (titania, alumina) or metals (Ni, Fe, Ag etc.) is investigated. A scaling law is found between average aggregate projected area and equivalent number of constituent primary particles during sintering: from fractal-like agglomerates to aggregates and eventually compact particles (e.g. spheres). This is essentially a relation independent of time, material properties and sintering mechanisms. It is used to estimate the equivalent primary particle diameter and number in aggregates. The evolution of aggregate morphology or structure is quantified by the effective fractal dimension (Df ) and mass-mobility exponent (Dfm ) and the corresponding prefactors. The Dfm increases monotonically during sintering converging to 3 for a compact particle. Therefore Dfm and its prefactor could be used to gauge the degree or extent of sintering of agglomerates made by a known collision mechanism. This analysis is exemplified by comparison to experiments of silver nanoparticle aggregates sintered at different temperatures in an electric tube furnace.

  6. Quantifying convergence in the sciences

    Directory of Open Access Journals (Sweden)

    Sara Lumbreras

    2016-02-01

    Full Text Available Traditional epistemological models classify knowledge into separate disciplines with different objects of study and specific techniques, with some frameworks even proposing hierarchies (such as Comte’s. According to thinkers such as John Holland or Teilhard de Chardin, the advancement of science involves the convergence of disciplines. This proposed convergence can be studied in a number of ways, such as how works impact research outside a specific area (citation networks or how authors collaborate with other researchers in different fields (collaboration networks. While these studies are delivering significant new insights, they cannot easily show the convergence of different topics within a body of knowledge. This paper attempts to address this question in a quantitative manner, searching for evidence that supports the idea of convergence in the content of the sciences themselves (that is, whether the sciences are dealing with increasingly the same topics. We use Latent Dirichlet Analysis (LDA, a technique that is able to analyze texts and estimate the relative contributions of the topics that were used to generate them. We apply this tool to the corpus of the Santa Fe Institute (SFI working papers, which spans research on Complexity Science from 1989 to 2015. We then analyze the relatedness of the different research areas, the rise and demise of these sub-disciplines over time and, more broadly, the convergence of the research body as a whole. Combining the topic structure obtained from the collected publication history of the SFI community with techniques to infer hierarchy and clustering, we reconstruct a picture of a dynamic community which experiences trends, periodically recurring topics, and shifts in the closeness of scholarship over time. We find that there is support for convergence, and that the application of quantitative methods such as LDA to the study of knowledge can provide valuable insights that can help

  7. The Convergence of Alexithymia Measures

    Directory of Open Access Journals (Sweden)

    Reitske Meganck

    2011-11-01

    Full Text Available The construct of alexithymia is most frequently measured by means of the 20-item Toronto Alexithymia Scale (TAS-20. However a number of other instruments have been developed to compensate for problems with measuring alexithymia through self-report measures. Convergence between the different alexithymia measures is rarely studied. This study investigates the convergence among the TAS-20, the Observer Alexithymia Scale (OAS, the Toronto Structured Interview for Alexithymia (TSIA, the modified Beth Israel Hospital Psychosomatic Questionnaire (M-BIQ, and the alexithymia dimensions as judged by the treating psychologist in an inpatient sample ('N' = 80. Correlations between the total scores were all significant. However exploratory factor analyses of these measures and their subscales indicate that they do not tap into one underlying factor. It is concluded that the TSIA and the M-BIQ are the best indicators of alexithymia, yet a multi-method approach and care in interpreting results are warranted.

  8. Proliferating Connections and Communicating Convergence

    Directory of Open Access Journals (Sweden)

    Aylish Wood

    2008-01-01

    Full Text Available In this paper I use the work of Niklas Luhmann to explore what pressure the concept of convergence exerts over how we communicate about the changing expressive practices of digital games following the emergence of digital technologies. My claim will be that in its current form, convergence privileges either the human users of technological platforms, or the combination of aesthetic conventions from different media what connects is either the user or the aesthetic code. While neither of these two positions would be likely to deny a reliance on the interplay between humans and technologies, such an interplay is taken for granted rather than explored. By using Luhmann’s version of systems theory, I argue that we can more effectively grasp the interplay of human and technological participants by understanding their combined roles in changing expressive practices.

  9. Clusters, Convergence, and Economic Performance

    OpenAIRE

    Mercedes Delgado; Porter, Michael E.; Scott Stern

    2010-01-01

    This paper evaluates the role of regional cluster composition in the economic performance of industries, clusters and regions. On the one hand, diminishing returns to specialization in a location can result in a convergence effect: the growth rate of an industry within a region may be declining in the level of activity of that industry. At the same time, positive spillovers across complementary economic activities provide an impetus for agglomeration: the growth rate of an industry within a r...

  10. Analytic practice: convergences and divergences.

    Science.gov (United States)

    Laks Eizirik, Cláudio

    2010-04-01

    The author discusses current convergences and divergences concerning analytic practice. After presenting a clinical vignette that can be understood differently according to different theoretical approaches, he discusses Wallerstein's proposal of a common ground in psychoanalysis and suggests that the present state of the art indicates that psychoanalysis is a pluralistic discipline, with different ways of training and practising it, and that the main challenge is to improve our ability to listen to and to learn from different approaches.

  11. Convergence Patterns in Latin America

    DEFF Research Database (Denmark)

    Quiroga, Paola Andrea Barrientos

    characteristics, and external shocks in the region. I study three important phases, following Thorp (1998): from 1900 to 1930, the exporting phase, from 1931 to 1974, the industrialization phase, and from 1975 to 2007, the globalization phase. During the last two phases, I find strong evidence of convergence...... among those countries that succeeded in industrializing and/or building good institutions. The reason is that technology dissusion and capital accumulation is easier when these 2 phenomena occur....

  12. Convergence of multiple ergodic averages

    OpenAIRE

    Host, Bernard

    2006-01-01

    These notes are based on a course for a general audience given at the Centro de Modeliamento Matem\\'atico of the University of Chile, in December 2004. We study the mean convergence of multiple ergodic averages, that is, averages of a product of functions taken at different times. We also describe the relations between this area of ergodic theory and some classical and some recent results in additive number theory.

  13. Surface meshing with curvature convergence

    KAUST Repository

    Li, Huibin

    2014-06-01

    Surface meshing plays a fundamental role in graphics and visualization. Many geometric processing tasks involve solving geometric PDEs on meshes. The numerical stability, convergence rates and approximation errors are largely determined by the mesh qualities. In practice, Delaunay refinement algorithms offer satisfactory solutions to high quality mesh generations. The theoretical proofs for volume based and surface based Delaunay refinement algorithms have been established, but those for conformal parameterization based ones remain wide open. This work focuses on the curvature measure convergence for the conformal parameterization based Delaunay refinement algorithms. Given a metric surface, the proposed approach triangulates its conformal uniformization domain by the planar Delaunay refinement algorithms, and produces a high quality mesh. We give explicit estimates for the Hausdorff distance, the normal deviation, and the differences in curvature measures between the surface and the mesh. In contrast to the conventional results based on volumetric Delaunay refinement, our stronger estimates are independent of the mesh structure and directly guarantee the convergence of curvature measures. Meanwhile, our result on Gaussian curvature measure is intrinsic to the Riemannian metric and independent of the embedding. In practice, our meshing algorithm is much easier to implement and much more efficient. The experimental results verified our theoretical results and demonstrated the efficiency of the meshing algorithm. © 2014 IEEE.

  14. User Configurations and Convergence in Consumer Electronics

    DEFF Research Database (Denmark)

    Jørgensen, Ulrik

    2000-01-01

    Convergence has been a technical fix motivated by the digital developments in media technologies.......Convergence has been a technical fix motivated by the digital developments in media technologies....

  15. Converging shocks for DSD modelling

    Science.gov (United States)

    Matignon, Christophe

    2013-06-01

    Modelling of pyrotechnic systems requires both, a good understanding and precise prediction capabilities of the dynamics of detonation. When using insensitive high explosives IHE (such as TATB-based explosives) the interaction of the detonation front with the confinement can lead to very different detonation velocities. One of the most popular engineering tools used to model this behaviour is the Detonation Shock Dynamics (DSD). In the DSD assumption, the detonation front propagates at a normal shock velocity (Dn) which depends only on its local curvature (κ). For divergent detonations, the DSD limit is very well established both experimentally and theoretically and one can easily propose a model (which obeys the 1D quasi-steady weakly curved detonation theory) to reproduce this behavior. We propose to extend the DSD theory to slightly convergent detonation fronts and to validate it against experimental data. Two series of experiments were carried out. The first series was designed to collect precise information regarding converging detonation. Usually, in such configurations, the detonation is non steady, making precise and simultaneous measurements of velocity and curvature difficult to achieve. The originality of the proposed setup is to drive a self similar convergent detonation at constant speed in an IHE rod by an external explosive tube of greater detonation velocity (allowing an accurate recording of both velocity and curvature). A wide range EOS/reaction rate model (inspired from previous works of Wescott et al.) was then calibrated to reproduce both the strong shock initiation and the newly extended (Dn- κ) law. This model can be used to perform either direct numerical simulation (DNS) on fine resolved mesh grid, or its reduced PZR model (DSD based) on a much coarser grid. This model was then successfully validated against the second series of experiments involving a detonation propagating around an obstacle and exhibiting a non steady converging front

  16. Convergence of barycentric coordinates to barycentric kernels

    KAUST Repository

    Kosinka, Jiří

    2016-02-12

    We investigate the close correspondence between barycentric coordinates and barycentric kernels from the point of view of the limit process when finer and finer polygons converge to a smooth convex domain. We show that any barycentric kernel is the limit of a set of barycentric coordinates and prove that the convergence rate is quadratic. Our convergence analysis extends naturally to barycentric interpolants and mappings induced by barycentric coordinates and kernels. We verify our theoretical convergence results numerically on several examples.

  17. Fiber-wireless convergence in next-generation communication networks systems, architectures, and management

    CERN Document Server

    Chang, Gee-Kung; Ellinas, Georgios

    2017-01-01

    This book investigates new enabling technologies for Fi-Wi convergence. The editors discuss Fi-Wi technologies at the three major network levels involved in the path towards convergence: system level, network architecture level, and network management level. The main topics will be: a. At system level: Radio over Fiber (digitalized vs. analogic, standardization, E-band and beyond) and 5G wireless technologies; b. Network architecture level: NGPON, WDM-PON, BBU Hotelling, Cloud Radio Access Networks (C-RANs), HetNets. c. Network management level: SDN for convergence, Next-generation Point-of-Presence, Wi-Fi LTE Handover, Cooperative MultiPoint. • Addresses the Fi-Wi convergence issues at three different levels, namely at the system level, network architecture level, and network management level • Provides approaches in communication systems, network architecture, and management that are expected to steer the evolution towards fiber-wireless convergence • Contributions from leading experts in the field of...

  18. Convergence analysis of combinations of different methods

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Y. [Clarkson Univ., Potsdam, NY (United States)

    1994-12-31

    This paper provides a convergence analysis for combinations of different numerical methods for solving systems of differential equations. The author proves that combinations of two convergent linear multistep methods or Runge-Kutta methods produce a new convergent method of which the order is equal to the smaller order of the two original methods.

  19. Evolution of Scale Worms

    DEFF Research Database (Denmark)

    Gonzalez, Brett Christopher

    ) caves, and the interstitium, recovering six monophyletic clades within Aphroditiformia: Acoetidae, Aphroditidae, Eulepethidae, Iphionidae, Polynoidae, and Sigalionidae (inclusive of the former ‘Pisionidae’ and ‘Pholoidae’), respectively. Tracing of morphological character evolution showed a high degree...... of adaptability and convergent evolution between relatively closely related scale worms. While some morphological and behavioral modifications in cave polynoids reflected troglomorphism, other modifications like eye loss were found to stem from a common ancestor inhabiting the deep sea, further corroborating...... the deep sea ancestry of scale worm cave fauna. In conclusion, while morphological characterization across Aphroditiformia appears deceptively easy due to the presence of elytra, convergent evolution during multiple early radiations across wide ranging habitats have confounded our ability to reconstruct...

  20. Air quality management: evolution of policy and practice in the UK as exemplified by the experience of English local government

    Science.gov (United States)

    Beattie, C. I.; Longhurst, J. W. S.; Woodfield, N. K.

    The air quality management (AQM) framework in the UK is designed to be an effects-based solution to air pollutants currently affecting human health. The AQM process has been legislated through The Environment Act 1995, which required the National Air Quality Strategy (NAQS) to be published. AQM practice and capability within local authorities has flourished since the publication of the NAQS in March 1997. This paper outlines the policy framework within which the UK operates, both at a domestic and European level, and reviews the air quality management process relating to current UK policy and EU policy. Data from questionnaire surveys are used to indicate the involvement of various sectors of local government in the air quality management process. These data indicate an increasing use of monitoring, and use of air dispersion modelling by English local authorities. Data relating to the management of air quality, for example, the existence and work of air quality groups, dissemination of information to the public and policy measures in place on a local scale to improve air quality, have also been reported. The UK NAQS has been reviewed in 1999 to reflect developments in European legislation, technological and scientific advances, improved air pollution modelling techniques and an increasingly better understanding of the socio-economic issues involved. The AQM process, as implemented by UK local authorities, provides an effective model for other European member states with regards to the implementation of the Air Quality Framework Directive. The future direction of air quality policy in the UK is also discussed.

  1. Evolution of substrate recognition sites (SRSs) in cytochromes P450 from Apiaceae exemplified by the CYP71AJ subfamily

    DEFF Research Database (Denmark)

    Dueholm, Bjørn; Krieger, Celia; Drew, Damian

    2015-01-01

    belonging to the Apioideae subfamily of Apiaceae and have been described as being involved in the defence reaction against phytophageous insects. Results: A bloom in the cytochromes P450 CYP71AJ subfamily has been identified, showing at least 2 clades and 6 subclades within the CYP71AJ subfamily. Two...... of the subclades were functionally assigned to the biosynthesis of furanocoumarins. Six substrate recognition sites (SRS1-6) important for the enzymatic conversion were investigated in the described cytochromes P450 and display significant variability within the CYP71AJ subfamily. Homology models underline...... a significant modification of the accession to the iron atom, which might explain the difference of the substrate specificity between the cytochromes P450 restricted to furanocoumarins as substrates and the orphan CYP71AJ. Conclusion: Two subclades functionally assigned to the biosynthesis of furanocoumarins...

  2. Sustainability and Convergence: The Future of Corporate Governance Systems?

    Directory of Open Access Journals (Sweden)

    Daniela M. Salvioni

    2016-11-01

    Full Text Available In today’s world, a sustainable approach to corporate governance can be a source of competitive advantage and a long-term success factor for any firm. Sustainable governance requires that the board of directors considers economic, social and environmental expectations in an integrated way, no matter what ownership structure and formal rules of corporate governance apply to the company: this mitigates the traditional differences between insider and outsider systems of corporate governance. Previous studies failed to consider the contribution of sustainability in the process of corporate governance convergence. Therefore, the aim of this article is to fill the gap in the existing literature by means of a qualitative analysis, supporting the international debate about convergence of corporate governance systems. The article describes the evolution of outsider and insider systems in the light of the increasing importance of sustainability in the board’s decision-making and firm’s operation to satisfy the needs of all the company’s stakeholders. According to this, a qualitative content analysis developed with a directed approach completes the theoretical discussion, demonstrating that sustainability can bring de facto convergence between outsider and insider corporate governance systems. The article aims to be a theoretical starting point for future research, the findings of which could also have practical implications: the study encourages the policy makers to translate the sustainable business best practices into laws and recommendations, strengthening the mutual influence between formal and substantial convergence.

  3. The identification of concerted convergence in insect heads corroborates palaeoptera.

    Science.gov (United States)

    Blanke, Alexander; Greve, Carola; Wipfler, Benjamin; Beutel, Rolf G; Holland, Barbara R; Misof, Bernhard

    2013-03-01

    The relationships of the 3 major clades of winged insects-Ephemeroptera, Odonata, and Neoptera-are still unclear. Many morphologists favor a clade Metapterygota (Odonata +Neoptera), but Chiastomyaria (Ephemeroptera + Neoptera) or Palaeoptera (Ephemeroptera +Odonata) has also been supported in some older and more recent studies. A possible explanation for the difficulties in resolving these relationships is concerted convergence-the convergent evolution of entire character complexes under the same or similar selective pressures. In this study, we analyze possible instances of this phenomenon in the context of head structures of Ephemeroptera, Odonata, and Neoptera. We apply a recently introduced formal approach to detect the occurrence of concerted convergence. We found that characters of the tentorium and mandibles in particular, but also some other head structures, have apparently not evolved independently, and thus can cause artifacts in tree reconstruction. Our subsequent analyses, which exclude character sets that may be affected by concerted convergence, corroborate the Palaeoptera concept. We show that the analysis of homoplasy and its influence on tree inference can be formally improved with important consequences for the identification of incompatibilities between data sets. Our results suggest that modified weighting (or exclusion of characters) in cases of formally identified correlated cliques of characters may improve morphology-based tree reconstruction.

  4. I-Ching Divination Evolutionary Algorithm and its Convergence Analysis.

    Science.gov (United States)

    Chen, C L Philip; Zhang, Tong; Chen, Long; Tam, Sik Chung

    2017-01-01

    An innovative simulated evolutionary algorithm (EA), called I-Ching divination EA (IDEA), and its convergence analysis are proposed and investigated in this paper. Inherited from ancient Chinese culture, I-Ching divination has always been used as a divination system in traditional and modern China. There are three operators evolved from I-Ching transformations in this new optimization algorithm, intrication operator, turnover operator, and mutual operator. These new operators are very flexible in the evolution procedure. Additionally, two new spaces are defined in this paper, which are denoted as hexagram space and state space. In order to analyze the convergence property of I-Ching divination algorithm, Markov model was adopted to analyze the characters of the operators. Meanwhile, the proposed algorithm is proved to be a homogeneous Markov chain with the positive transition matrix. After giving some basic concepts of necessary theorems, definition of admissible functions and I-Ching map, a precise proof of the states converge to the global optimum is presented. Compared with the genetic algorithm, particle swarm optimization, and differential evolution algorithm, our proposed IDEA is much faster in reaching the global optimum.

  5. The influence of cultural background in intercultural dementia care: exemplified by Sami patients.

    Science.gov (United States)

    Hanssen, Ingird

    2013-06-01

    To gain knowledge about how the original culture may influence communication and interaction with institutionalised patients with dementia and of what particular cultural aspects may come to the fore, exemplified by Sami patients. Qualitative narrative interviews with 15 interviewees, family members of Sami patients with dementia and nursing staff experienced with dementia care were conducted. Hermeneutic, thematic analysis was used. Although the way dementia influence mental functions, language, etc. is universal, behaviours, reactions and responses may be coloured by the patient's background culture. Knowledge of language, cultural codes and the patient's former life are primary keys to understanding. Rhythm of life, spirituality, singing and tangible aspects of traditional culture like clothes and food constitute important aspects of culture-appropriate care. © 2012 Nordic College of Caring Science.

  6. Anatexis and metamorphism in tectonically thickened continental crust exemplified by the Sevier hinterland, western North America

    Science.gov (United States)

    Patino Douce, Alberto E.; Humphreys, Eugene D.; Johnston, A. Dana

    1990-01-01

    This paper presents a thermal and petrologic model of anatexis and metamorphism in regions of crustal thickening exemplified by the Sevier hinterland in western North America, and uses the model to examine the geological and physical processes leading to crustally derived magmatism. The results of numerical experiments show that anatexis was an inevitable end-product of Barrovian metamorphism in the thickened crust of the late Mesozoic Sevier orogenic belt and that the advection of heat across the lithosphere, in the form of mantle-derived mafic magmas, was not required for melting of metasedimentary rocks. It is suggested that, in the Sevier belt, as in other intracontinental orogenic belts, anatexis occurred in the midcrust and not at the base of the crust.

  7. SCORE DIGITAL TECHNOLOGY: THE CONVERGENCE

    Directory of Open Access Journals (Sweden)

    Chernyshov Alexander V.

    2013-12-01

    Full Text Available Explores the role of digital scorewriters in today's culture, education, and music industry and media environment. The main principle of the development of software is not only publishing innovation (relating to the sheet music, and integration into the area of composition, arrangement, education, creative process for works based on digital technology (films, television and radio broadcasting, Internet, audio and video art. Therefore the own convergence of musically-computer technology is a total phenomenon: notation program combined with means MIDI-sequencer, audio and video editor. The article contains the unique interview with the creator of music notation processors.

  8. Technology Convergence and National Security

    Science.gov (United States)

    2010-08-25

    best minds from science, medicine, philosophy and the arts  at the  Medici  Court in 15th Century Florence catalyzed the Renaissance. It was the...transdisciplinary nature of that convergence that was critical. Sandro Botticelli Michelangelo Buonarroti Lorenzo  the Magnificent Andrea del Verrocchio Leonardo

  9. Remarkable convergent evolution in specialized parasitic Thecostraca (Crustacea)

    DEFF Research Database (Denmark)

    Pérez-Losada, Marcos; Høeg, Jens Thorvald; Crandall, Keith A

    2009-01-01

    ,402), Histone H3 (328)] and 41 larval characters in seven facetotectans, five ascothoracidans, three acrothoracicans, 25 rhizocephalans and 39 thoracicans (ingroup) and 12 Malacostraca and 10 Copepoda (outgroup). Maximum parsimony, maximum likelihood and Bayesian analyses showed the Facetotecta, Ascothoracida...

  10. Convergent evolution of complex brains and high intelligence.

    Science.gov (United States)

    Roth, Gerhard

    2015-12-19

    Within the animal kingdom, complex brains and high intelligence have evolved several to many times independently, e.g. among ecdysozoans in some groups of insects (e.g. blattoid, dipteran, hymenopteran taxa), among lophotrochozoans in octopodid molluscs, among vertebrates in teleosts (e.g. cichlids), corvid and psittacid birds, and cetaceans, elephants and primates. High levels of intelligence are invariantly bound to multimodal centres such as the mushroom bodies in insects, the vertical lobe in octopodids, the pallium in birds and the cerebral cortex in primates, all of which contain highly ordered associative neuronal networks. The driving forces for high intelligence may vary among the mentioned taxa, e.g. needs for spatial learning and foraging strategies in insects and cephalopods, for social learning in cichlids, instrumental learning and spatial orientation in birds and social as well as instrumental learning in primates. © 2015 The Author(s).

  11. Twitter evolution: converging mechanisms in birdsong and human speech.

    Science.gov (United States)

    Bolhuis, Johan J; Okanoya, Kazuo; Scharff, Constance

    2010-11-01

    Vocal imitation in human infants and in some orders of birds relies on auditory-guided motor learning during a sensitive period of development. It proceeds from 'babbling' (in humans) and 'subsong' (in birds) through distinct phases towards the full-fledged communication system. Language development and birdsong learning have parallels at the behavioural, neural and genetic levels. Different orders of birds have evolved networks of brain regions for song learning and production that have a surprisingly similar gross anatomy, with analogies to human cortical regions and basal ganglia. Comparisons between different songbird species and humans point towards both general and species-specific principles of vocal learning and have identified common neural and molecular substrates, including the forkhead box P2 (FOXP2) gene.

  12. Holocentric chromosomes: convergent evolution, meiotic adaptations, and genomic analysis.

    Science.gov (United States)

    Melters, Daniël P; Paliulis, Leocadia V; Korf, Ian F; Chan, Simon W L

    2012-07-01

    In most eukaryotes, the kinetochore protein complex assembles at a single locus termed the centromere to attach chromosomes to spindle microtubules. Holocentric chromosomes have the unusual property of attaching to spindle microtubules along their entire length. Our mechanistic understanding of holocentric chromosome function is derived largely from studies in the nematode Caenorhabditis elegans, but holocentric chromosomes are found over a broad range of animal and plant species. In this review, we describe how holocentricity may be identified through cytological and molecular methods. By surveying the diversity of organisms with holocentric chromosomes, we estimate that the trait has arisen at least 13 independent times (four times in plants and at least nine times in animals). Holocentric chromosomes have inherent problems in meiosis because bivalents can attach to spindles in a random fashion. Interestingly, there are several solutions that have evolved to allow accurate meiotic segregation of holocentric chromosomes. Lastly, we describe how extensive genome sequencing and experiments in nonmodel organisms may allow holocentric chromosomes to shed light on general principles of chromosome segregation.

  13. Convergent evolution of vascular optimization in kelp (Laminariales)

    DEFF Research Database (Denmark)

    Drobnitch, Sarah Tepler; Jensen, Kaare Hartvig; Prentice, Paige

    2015-01-01

    scaling relationships between all tested vascular parameters and agrees with our model; other species within the Laminariales display weak or inconsistent vascular allometries. The lack of universal scaling in the kelps and the presence of optimized transport anatomy in M. pyrifera raises important...

  14. Convergent Evolution of Sodium Ion Selectivity in Metazoan Neuronal Signaling

    Directory of Open Access Journals (Sweden)

    Maya Gur Barzilai

    2012-08-01

    Full Text Available Ion selectivity of metazoan voltage-gated Na+ channels is critical for neuronal signaling and has long been attributed to a ring of four conserved amino acids that constitute the ion selectivity filter (SF at the channel pore. Yet, in addition to channels with a preference for Ca2+ ions, the expression and characterization of Na+ channel homologs from the sea anemone Nematostella vectensis, a member of the early-branching metazoan phylum Cnidaria, revealed a sodium-selective channel bearing a noncanonical SF. Mutagenesis and physiological assays suggest that pore elements additional to the SF determine the preference for Na+ in this channel. Phylogenetic analysis assigns the Nematostella Na+-selective channel to a channel group unique to Cnidaria, which diverged >540 million years ago from Ca2+-conducting Na+ channel homologs. The identification of Cnidarian Na+-selective ion channels distinct from the channels of bilaterian animals indicates that selectivity for Na+ in neuronal signaling emerged independently in these two animal lineages.

  15. The Evolution of Electricity Prices in The EU since the Single European Act

    National Research Council Canada - National Science Library

    T Robinson

    2008-01-01

    .... This paper considers the impact of EU Directives on the evolution of electricity prices. Three empirical tests for convergence are applied to prices for ten EU countries; a simple test for β-convergence...

  16. Ocular convergence deficits in schizophrenia

    Directory of Open Access Journals (Sweden)

    Mark S Bolding

    2012-10-01

    Full Text Available Individuals with schizophrenia have been reported to exhibit a higher prevalence of convergence insufficiency (CI than the normal adult population. The purpose of this study was to determine if individuals with schizophrenia exhibit clinical signs of CI and to determine if the Convergence Insufficiency Symptom Survey (CISS is an effective instrument for identifying CI in this population.Twenty participants with schizophrenia (SZ and 20 healthy controls (HC completed the study. The prevalence of CI (15% in the SZ group was slightly higher than reported norms, but the difference was not significant. The SZ group had significantly higher scores on the CISS than the HC group, but the CISS scores did not correlate with clinical measures of CI in individuals with SZ. The only exception was that SZ patients had a significantly reduced fusional reserve as determined by Sheard’s criteria. Further study is needed to determine why individuals with schizophrenia reported symptoms associated with CI even though clinical measures did not support this diagnosis.

  17. Value Creation Through Integrated Networks and Convergence

    Energy Technology Data Exchange (ETDEWEB)

    De Martini, Paul; Taft, Jeffrey D.

    2015-04-01

    Customer adoption of distributed energy resources and public policies are driving changes in the uses of the distribution system. A system originally designed and built for one-way energy flows from central generating facilities to end-use customers is now experiencing injections of energy from customers anywhere on the grid and frequent reversals in the direction of energy flow. In response, regulators and utilities are re-thinking the design and operations of the grid to create more open and transactive electric networks. This evolution has the opportunity to unlock significant value for customers and utilities. Alternatively, failure to seize this potential may instead lead to an erosion of value if customers seek to defect and disconnect from the system. This paper will discuss how current grid modernization investments may be leveraged to create open networks that increase value through the interaction of intelligent devices on the grid and prosumerization of customers. Moreover, even greater value can be realized through the synergistic effects of convergence of multiple networks. This paper will highlight examples of the emerging nexus of non-electric networks with electricity.

  18. Convergent Validity of the PUTS

    Directory of Open Access Journals (Sweden)

    Valerie Cathérine Brandt

    2016-04-01

    Full Text Available Premonitory urges are a cardinal feature in Gilles de la Tourette syndrome. Severity of premonitory urges can be assessed with the Premonitory Urge for Tic Disorders Scale (PUTS. However, convergent validity of the measure has been difficult to assess due to the lack of other urge measures.We investigated the relationship between average real-time urge intensity assessed by an in-house developed real-time urge monitor, measuring urge intensity continuously for 5mins on a visual analogue scale, and general urge intensity assessed by the PUTS in 22 adult Tourette patients (mean age 29.8+/- 10.3; 19 male. Additionally, underlying factors of premonitory urges assessed by the PUTS were investigated in the adult sample using factor analysis and were replicated in 40 children and adolescents diagnosed with Tourette syndrome (mean age 12.05 +/- 2.83 SD, 31 male.Cronbach’s alpha for the PUTS10 was acceptable (α = .79 in the adult sample. Convergent validity between average real-time urge intensity scores (as assessed with the real-time urge monitor and the 10-item version of the PUTS (r = .64 and the 9-item version of the PUTS (r = .66 was good. A factor analysis including the 10 items of the PUTS and average real-time urge intensity scores revealed three factors. One factor included the average real-time urge intensity score and appeared to measure urge intensity, while the other two factors can be assumed to reflect the (sensory quality of urges and subjective control, respectively. The factor structure of the 10 PUTS items alone was replicated in a sample of children and adolescents.The results indicate that convergent validity between the PUTS and the real-time urge assessment monitor is good. Furthermore, the results suggest that the PUTS might assess more than one dimension of urges and it may be worthwhile developing different sub-scales of the PUTS assessing premonitory urges in terms of intensity and quality, as well as subjectively

  19. Cosmic Convergence: Art and Science

    Science.gov (United States)

    Mayo, Elizabeth A.; Zisholtz, E.; Hilton, H.

    2010-01-01

    The I.P. Stanback Museum and Planetarium is a major educational and teaching resource for South Carolina State University, K-12 schools, other universities and the community of Orangeburg and well beyond. The concept of creating a museum with a planetarium on the campus of SC State was ahead of its time. Today scholars are writing about the unity of creative disciplines. Through its integration of the arts, humanities and sciences, the Stanback, the only art museum with a planetarium at any of the Historically Black Colleges and Universities and one of the few in the nation, stands in the forefront of modern thinking. Cosmic Convergence: Art and Science, opening at the I.P. Stanback Museum and Planetarium in February 2010, will feature the works of Mildred Thompson (1936-2003), a prominent African American artist who worked in the media of painting, drawing, print making, sculpture, and photography. Thompson’s artwork shows the strong influences of her interest in physics, astronomy, and metaphysics as well as music and spiritualism. “My work in the visual arts is, and has always been, a continuous search for understanding. It is an expression of purpose and reflects a personal interpretation of the Universe.” Cosmic Convergence will explore the meeting of Art and Science through Mildred Thompson's work and the scientific basis of that work. The paintings and sculptures of the exhibit will be combined with astronomical images showing both the reality and interpretation of the surrounding Universe. Support for this work was provided by the NSF PAARE program to South Carolina State University under award AST-0750814.

  20. Regional Convergence and Sustainable Development in China

    Directory of Open Access Journals (Sweden)

    Fang Yang

    2016-01-01

    Full Text Available Based on the convergence theory of economic growth, this paper extends this concept to the human development index and carries out an empirical analysis of regional development in China between 1997 and 2006. Our research shows that the conditional convergence has been identified. Investment in fixed assets, government expenditure on education, health and infrastructure construction have positive effects on regional convergence of social development. Population weighted analysis of human development index provides support for weak convergence amongst provinces. Analysis of dynamics of regional distribution reveals the club convergence, which indicate two different convergence states. Central China is in the shade and lags behind, giving rise to the so-called “central downfall”. To solve this problem, the “Rise of Central China” Plan is necessary to promote the connection between coastal and inland regions of China and reduce the regional development gap.

  1. Vadose zone flow convergence test suite

    Energy Technology Data Exchange (ETDEWEB)

    Butcher, B. T. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-06-05

    Performance Assessment (PA) simulations for engineered disposal systems at the Savannah River Site involve highly contrasting materials and moisture conditions at and near saturation. These conditions cause severe convergence difficulties that typically result in unacceptable convergence or long simulation times or excessive analyst effort. Adequate convergence is usually achieved in a trial-anderror manner by applying under-relaxation to the Saturation or Pressure variable, in a series of everdecreasing RELAxation values. SRNL would like a more efficient scheme implemented inside PORFLOW to achieve flow convergence in a more reliable and efficient manner. To this end, a suite of test problems that illustrate these convergence problems is provided to facilitate diagnosis and development of an improved convergence strategy. The attached files are being transmitted to you describing the test problem and proposed resolution.

  2. Convergence on local labour markets in Poland

    OpenAIRE

    Kusideł, Ewa

    2011-01-01

    The purpose of presented study was to verify a hypothesis of convergence on local labor markets in Poland. Convergence phenomenon, understood as economic development levels balancing (falling differentiation) has been known since the mid- 1950s. In Poland the convergence problems have been a specific subject of research since the accession to the European Union and the implementation of cohesion policy whose financing is largely related to co...

  3. Modeling Risk Convergence for European Financial Markets

    Directory of Open Access Journals (Sweden)

    Radu LUPU

    2014-09-01

    Full Text Available This article studies the convergence of risk on a sample of 13 European indexes. We use a set of 31 model specifications of a significant number of models belonging to the GARCH class and on their estimates we build an aggregate index in a Value-at-Risk approach. We use this index as a base for our convergence analysis. The results indicate a positive and significant tendency of convergence growth for the European financial market

  4. Increasing dominance of IT in ICT convergence

    DEFF Research Database (Denmark)

    Henten, Anders; Tadayoni, Reza

    The aim of the paper is to examine the increasing dominance of IT companies in the converging ICT industry and, on the basis of this development, to contribute to extending the theoretical understanding of market and industry convergence in the ICT area.......The aim of the paper is to examine the increasing dominance of IT companies in the converging ICT industry and, on the basis of this development, to contribute to extending the theoretical understanding of market and industry convergence in the ICT area....

  5. The influence of channel deepening on estuarine turbidity levels and dynamics, as exemplified by the Ems estuary

    NARCIS (Netherlands)

    de Jonge, V.N.; Schuttelaars, H.M.; van Beusekom, J.E.E.; Talke, S.A.|info:eu-repo/dai/nl/304823554; de Swart, H.E.|info:eu-repo/dai/nl/073449725

    2014-01-01

    Active deepening of tidal channels usually results in the alteration of the vertical and the horizontal tide. This may lead to concurrent significant increases in mean suspended matter concentrations (SPM) in coastal plain estuaries, the turbidity maximum (ETM) included. This is exemplified by an

  6. Evo-devo, deep homology and FoxP2: implications for the evolution of speech and language.

    Science.gov (United States)

    Scharff, Constance; Petri, Jana

    2011-07-27

    The evolution of novel morphological features, such as feathers, involves the modification of developmental processes regulated by gene networks. The fact that genetic novelty operates within developmental constraints is the central tenet of the 'evo-devo' conceptual framework. It is supported by findings that certain molecular regulatory pathways act in a similar manner in the development of morphological adaptations, which are not directly related by common ancestry but evolved convergently. The Pax6 gene, important for vision in molluscs, insects and vertebrates, and Hox genes, important for tetrapod limbs and fish fins, exemplify this 'deep homology'. Recently, 'evo-devo' has expanded to the molecular analysis of behavioural traits, including social behaviour, learning and memory. Here, we apply this approach to the evolution of human language. Human speech is a form of auditory-guided, learned vocal motor behaviour that also evolved in certain species of birds, bats and ocean mammals. Genes relevant for language, including the transcription factor FOXP2, have been identified. We review evidence that FoxP2 and its regulatory gene network shapes neural plasticity in cortico-basal ganglia circuits underlying the sensory-guided motor learning in animal models. The emerging picture can help us understand how complex cognitive traits can 'descend with modification'.

  7. Evo-devo, deep homology and FoxP2: implications for the evolution of speech and language

    Science.gov (United States)

    Scharff, Constance; Petri, Jana

    2011-01-01

    The evolution of novel morphological features, such as feathers, involves the modification of developmental processes regulated by gene networks. The fact that genetic novelty operates within developmental constraints is the central tenet of the ‘evo-devo’ conceptual framework. It is supported by findings that certain molecular regulatory pathways act in a similar manner in the development of morphological adaptations, which are not directly related by common ancestry but evolved convergently. The Pax6 gene, important for vision in molluscs, insects and vertebrates, and Hox genes, important for tetrapod limbs and fish fins, exemplify this ‘deep homology’. Recently, ‘evo-devo’ has expanded to the molecular analysis of behavioural traits, including social behaviour, learning and memory. Here, we apply this approach to the evolution of human language. Human speech is a form of auditory-guided, learned vocal motor behaviour that also evolved in certain species of birds, bats and ocean mammals. Genes relevant for language, including the transcription factor FOXP2, have been identified. We review evidence that FoxP2 and its regulatory gene network shapes neural plasticity in cortico-basal ganglia circuits underlying the sensory-guided motor learning in animal models. The emerging picture can help us understand how complex cognitive traits can ‘descend with modification’. PMID:21690130

  8. Biomass transition metal hydrogen-evolution electrocatalysts and electrodes

    Science.gov (United States)

    Chen, Wei-Fu; Iyer, Shweta; Iyer, Shilpa; Sasaki, Kotaro; Muckerman, James T.; Fujita, Etsuko

    2017-02-28

    A catalytic composition from earth-abundant transition metal salts and biomass is disclosed. A calcined catalytic composition formed from soybean powder and ammonium molybdate is specifically exemplified herein. Methods for making the catalytic composition are disclosed as are electrodes for hydrogen evolution reactions comprising the catalytic composition.

  9. Bringing Javanesse Traditional Dance into Basic Physics Class: Exemplifying Projectile Motion through Video Analysis

    Science.gov (United States)

    Handayani, Langlang; Prasetya Aji, Mahardika; Susilo; Marwoto, Putut

    2016-08-01

    An alternative approach of an arts-based instruction for Basic Physics class has been developed through the implementation of video analysis of a Javanesse traditional dance: Bambangan Cakil. A particular movement of the dance -weapon throwing- was analyzed by employing the LoggerPro software package to exemplify projectile motion. The results of analysis indicated that the movement of the thrown weapon in Bambangan Cakil dance provides some helping explanations of several physics concepts of projectile motion: object's path, velocity, and acceleration, in a form of picture, graph and also table. Such kind of weapon path and velocity can be shown via a picture or graph, while such concepts of decreasing velocity in y direction (weapon moving downward and upward) due to acceleration g can be represented through the use of a table. It was concluded that in a Javanesse traditional dance there are many physics concepts which can be explored. The study recommends to bring the traditional dance into a science class which will enable students to get more understanding of both physics concepts and Indonesia cultural heritage.

  10. Exemplifying whole-plant ozone uptake in adult forest trees of contrasting species and site conditions

    Energy Technology Data Exchange (ETDEWEB)

    Nunn, Angela J. [Ecophysiology of Plants, Department of Ecology, Technical University of Muenchen, Am Hochanger 13, D-85354 Freising, Bavaria (Germany)]. E-mail: nunn@wzw.tum.de; Wieser, Gerhard [Federal Research and Training Centre for Forests, Natural Hazards and Landscape, Unit Alpine Timberline Ecophysiology, Rennweg 1, 6020 Innsbruck (Austria); Metzger, Ursula [Ecophysiology of Plants, Department of Ecology, Technical University of Muenchen, Am Hochanger 13, D-85354 Freising, Bavaria (Germany); Loew, Markus [Ecophysiology of Plants, Department of Ecology, Technical University of Muenchen, Am Hochanger 13, D-85354 Freising, Bavaria (Germany); Wipfler, Philip [Forest Yield Science, Technical University of Muenchen, Am Hochanger 13, D-85354 Freising (Germany); Haeberle, Karl-Heinz [Ecophysiology of Plants, Department of Ecology, Technical University of Muenchen, Am Hochanger 13, D-85354 Freising, Bavaria (Germany); Matyssek, Rainer [Ecophysiology of Plants, Department of Ecology, Technical University of Muenchen, Am Hochanger 13, D-85354 Freising, Bavaria (Germany)

    2007-04-15

    Whole-tree O{sub 3} uptake was exemplified for Picea abies, Fagus sylvatica and Larix decidua in stands at high and low altitude and contrasting water availability through sap flow measurement in tree trunks, intrinsically accounting for drought and boundary layer effects on O{sub 3} flux. O{sub 3} uptake of evergreen spruce per unit foliage area was enhanced by 100% at high relative to low elevation, whereas deciduous beech and larch showed similar uptake regardless of altitude. The responsiveness of the canopy conductance to water vapor and, as a consequence, O{sub 3} uptake to soil moisture and air humidity did not differ between species. Unifying findings at the whole-tree level will promote cause-effect based O{sub 3} risk assessment and modeling. - Sap flow-based assessment of whole-tree O{sub 3} uptake reflects similar responsiveness of canopy conductance and O{sub 3} uptake across contrasting tree species and site conditions.

  11. The bureaucratization of war: moral challenges exemplified by the covert lethal drone

    Directory of Open Access Journals (Sweden)

    Richard Adams

    2013-12-01

    Full Text Available This article interrogates the bureaucratization of war, incarnate in the covert lethal drone. Bureaucracies are criticized typically for their complexity, inefficiency, and inflexibility. This article is concerned with their moral indifference. It explores killing, which is so highly administered, so morally remote, and of such scale, that we acknowledge a covert lethal program. This is a bureaucratized program of assassination in contravention of critical human rights. In this article, this program is seen to compromise the advance of global justice. Moreover, the bureaucratization of lethal force is seen to dissolve democratic ideals from within. The bureaucracy isolates the citizens from lethal force applied in their name. People are killed, in the name of the State, but without conspicuous justification, or judicial review, and without informed public debate. This article gives an account of the risk associated with the bureaucratization of the State's lethal power. Exemplified by the covert drone, this is power with formidable reach. It is power as well, which requires great moral sensitivity. Considering the drone program, this article identifies challenges, which will become more prominent and pressing, as technology advances.

  12. Erich Fromm's productivity: creativity as exemplified by Joyce's blooming of Leopold and Molly.

    Science.gov (United States)

    Harrell, Valentina

    2005-01-01

    According to Erich Fromm, the productive character expresses what he called the life force in ways that are, by nature, artistic in quality. His valuing of the vital and the artistic, fueled by this life force in our potential to be human, serves as the cornerstone of his model of psychoanalysis. Gilbert Rose, author of Necessary Illusion: Art as "Witness", also has identified the parallel between analytic and artistic processes, building on the assumption that the therapeutic alliance and the aesthetic alliance are one and the same. In elaborating this assumption and extending the parallel between Rose and Fromm, I draw the conclusion that the qualities of relationships have an impact on one's ability to express oneself creatively, to live an artistic life--that is, to live productively. Psychoanalysis is, in practice, a process that is artistic, creative, and re-creative in nature. To the degree that authentic expression of emotionally charged implicit knowledge of the ineffable (the emotional life that resides deep in the bodymind) results in transformation and healing, the process is artistic in nature. This process is exemplified by examining the life and literary creations of James Joyce, especially Joyce's characters of Molly and Leopold Bloom in Ulysses.

  13. To converge or not to converge in environmental space: testing for similar environments between analogous succulent plants of North America and Africa.

    Science.gov (United States)

    Alvarado-Cárdenas, Leonardo O; Martínez-Meyer, Enrique; Feria, Teresa P; Eguiarte, Luis E; Hernández, Héctor M; Midgley, Guy; Olson, Mark E

    2013-06-01

    Convergent evolution is invoked to explain similarity between unrelated organisms in similar environments, but most evaluations of convergence analyse similarity of organismal attributes rather than of the environment. This study focuses on the globular succulent plants of the Americas, the cacti, and their counterparts in Africa in the ice-plant, spurge and milkweed families. Though often held up as paragons of convergent morphological evolution, the environmental similarity of these plants has remained largely unexamined from a quantitative perspective. Five hotspots (centres of high species diversity of globular succulents) were selected, two in Mexico and three in South Africa. Their environments were compared using niche modelling tools, randomization tests of niche similarity and multivariate analyses to test for environmental similarity. Although the sites selected have 'similar' but unrelated life forms, almost all our results highlighted more climate differences than similarities between the hotspots. Interprediction of niches within and between continents, a niche equivalence test, and MANOVA results showed significant differences. In contrast, a niche similarity test showed that the comparisons of Cuatrociénegas-Richtersveld, Huizache-Knersvlakte and Huizache-Richtersveld were similar. Differences in rainfall and temperature regimes and the potential effect of edaphic factors may be involved in the differences between the hotspots. In addition, differences in structure, morphology and physiology of the globular succulents may coincide with some of the climatic dissimilarities; i.e. given convergence as the evolution of similar morphologies under similar conditions, then it may be that differing environments diagnose inconspicuous morphological differences. Moreover, although fine-scale differences between sites were found, a coarser perspective shows that these sites are clearly similar as drylands with relatively moderate drought and mild temperatures

  14. Computer Science Approach to Information-Like Artifacts as Exemplified by Memes

    OpenAIRE

    Sabah Al-Fedaghi

    2015-01-01

    Providing information can be expanded to include systems that deliver information-like artifacts. They provide such “things” as advertisements, propaganda pieces, and meme artifacts. Memes are the subject of extensive intellectual debate in science and popular culture because it is claimed that parallels can be drawn between theories of cultural evolution manifested in memes, and theories of biological evolution. Memes are described as self-reproducing mental structures, intangible entities t...

  15. Societal response to nanotechnology: converging technologies–converging societal response research?

    NARCIS (Netherlands)

    Ronteltap, A.; Fischer, A.R.H.; Tobi, H.

    2011-01-01

    Nanotechnology is an emerging technology particularly vulnerable to societal unrest, which may hinder its further development. With the increasing convergence of several technological domains in the field of nanotechnology, so too could convergence of social science methods help to anticipate

  16. Concept for Mobility and Interconnections Aspects in Converged NGN-Based IPTV Architecture

    Directory of Open Access Journals (Sweden)

    Eugen Mikoczy

    2009-01-01

    Full Text Available The progress and evolution trends in the area of ICT and ICT infrastructure based on convergence processes create new opportunities. Service providers and network operators can provide a wide spectrum of multimedia services and applications to end users. The IPTV services represent a specific group of multimedia services which are in the sphere of interest of the telecommunication technical community but also subscribers. Standardization bodies like ETSI TISPAN or ITU-T have defined standards for NGN-based IPTV architecture and services (IMS and non-IMS. The paper evaluates possibilities and potential architecture for concept of converged NGN IPTV. New vision of the converged NGN IPTV architecture is presented together with proposed enhancements compared to IMS-based IPTV where single converged platform can serve fixed, mobile, or wireless terminals. The concept for IPTV service roaming with mobility support and different interconnection scenarios are discussed with intention to show potential user benefits.

  17. THE PATTERNS OF EU STOCK MARKETS. IS THERE A SIGN OF CONVERGENCE?

    Directory of Open Access Journals (Sweden)

    Muresan Diana

    2013-07-01

    Full Text Available This paper offers a preliminary analysis regarding the convergence of European stock markets. The sample consists of all 27 countries of European Union split in seven sub-groups related to income level, euro adoption and development level. The patterns analysed through this article are an important indication of expected convergence in EU stock markets. This study analyses the evolution and the trend of market capitalization and stocks traded and their correlation with some important determinants, namely inflation, capital formation, enrolment years, trade, FDI, government debt. Results show a negative correlation between initial level of market capitalisation and its growth rate and also of initial level of stocks traded and its growth rate. These results could be a sign of absolute convergence. Further research in this area is needed to see if there exists conditional convergence when heterogeneity among individuals is controlled for.

  18. Regional inequalities and convergence clubs in the European Union new member-states

    Directory of Open Access Journals (Sweden)

    Dimitris KALLIORAS

    2010-06-01

    Full Text Available The paper assesses on empirical grounds the level and the evolution of regional inequalities in each European Union new member-state (EU NMS and examines the possibility for the emergence of regional convergence clubs. The experience of the EU NMS is a unique situation, where relatively closed economic systems opened, almost at once, to the world economy and, at the same time, market mechanisms replaced central planning. Thus, understanding the spatial pattern of regional growth in the EU NMS may provide valuable insight for theory and policy. The application of non linear econometric models, which transcend the “all or nothing” logic behind conventional convergence analysis, has shown the existence of regional convergence clubs in many EU NMS. The identification of regional convergence clubs, irrespective of the pattern that emerges in each EU NMS, highlights the heterogeneous spatial impact of the EU economic integration process.

  19. Optimal Control of Evolution Mixed Variational Inclusions

    Energy Technology Data Exchange (ETDEWEB)

    Alduncin, Gonzalo, E-mail: alduncin@geofisica.unam.mx [Universidad Nacional Autónoma de México, Departamento de Recursos Naturales, Instituto de Geofísica (Mexico)

    2013-12-15

    Optimal control problems of primal and dual evolution mixed variational inclusions, in reflexive Banach spaces, are studied. The solvability analysis of the mixed state systems is established via duality principles. The optimality analysis is performed in terms of perturbation conjugate duality methods, and proximation penalty-duality algorithms to mixed optimality conditions are further presented. Applications to nonlinear diffusion constrained problems as well as quasistatic elastoviscoplastic bilateral contact problems exemplify the theory.

  20. Widespread flower color convergence in Solanaceae via alternate biochemical pathways.

    Science.gov (United States)

    Ng, Julienne; Smith, Stacey D

    2016-01-01

    Phenotypic convergence is rampant throughout the tree of life. While recent studies have made significant progress in ascertaining the proximate mechanisms underlying convergent phenotypes, less is known about the frequency and predictability with which convergent phenotypes arise via the same or multiple pathways at the macroevolutionary scale. We investigated the proximate causes and evolutionary patterns of red flower color in the tomato family, Solanaceae, using large-scale data mining and new sequence data to reconstruct a megaphylogeny of 1341 species. We then combined spectral and anatomical data to assess how many times red flowers have evolved, the relative contribution of different pathways to independent origins of red, and whether the underlying pathway is predicted by phylogenetic relatedness. We estimated at least 30 relatively recent origins of red flowers using anthocyanins, carotenoids, or a dual production of both pigments, with significant phylogenetic signal in the use of anthocyanins and dual production, indicating that closely related red-flowered species tend to employ the same mechanism for coloration. Our study is the first to test whether developmental pathways exhibit phylogenetic signal and implies that historical contingency strongly influences the evolution of new phenotypes. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

  1. Magnetically-Driven Convergent Instability Growth platform on Z.

    Energy Technology Data Exchange (ETDEWEB)

    Knapp, Patrick [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mattsson, Thomas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Martin, Matthew [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Benage, John F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jenkins, James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Albright, Brian James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-09-01

    Hydrodynamic instability growth is a fundamentally limiting process in many applications. In High Energy Density Physics (HEDP) systems such as inertial confinement fusion implosions and stellar explosions, hydro instabilities can dominate the evolution of the object and largely determine the final state achievable. Of particular interest is the process by which instabilities cause perturbations at a density or material interface to grow nonlinearly, introducing vorticity and eventually causing the two species to mix across the interface. Although quantifying instabilities has been the subject of many investigations in planar geometry, few have been done in converging geometry. During FY17, the team executed six convergent geometry instability experiments. Based on earlier results, the platform was redesigned and improved with respect to load centering at installation making the installation reproducible and development of a new 7.2 keV, Co He-a backlighter system to better penetrate the liner. Together, the improvements yielded significantly improved experimental results. The results in FY17 demonstrate the viability of using experiments on Z to quantify instability growth in cylindrically convergent geometry. Going forward, we will continue the partnership with staff and management at LANL to analyze the past experiments, compare to hydrodynamics growth models, and design future experiments.

  2. Borrowed alleles and convergence in serpentine adaptation.

    Science.gov (United States)

    Arnold, Brian J; Lahner, Brett; DaCosta, Jeffrey M; Weisman, Caroline M; Hollister, Jesse D; Salt, David E; Bomblies, Kirsten; Yant, Levi

    2016-07-19

    Serpentine barrens represent extreme hazards for plant colonists. These sites are characterized by high porosity leading to drought, lack of essential mineral nutrients, and phytotoxic levels of metals. Nevertheless, nature forged populations adapted to these challenges. Here, we use a population-based evolutionary genomic approach coupled with elemental profiling to assess how autotetraploid Arabidopsis arenosa adapted to a multichallenge serpentine habitat in the Austrian Alps. We first demonstrate that serpentine-adapted plants exhibit dramatically altered elemental accumulation levels in common conditions, and then resequence 24 autotetraploid individuals from three populations to perform a genome scan. We find evidence for highly localized selective sweeps that point to a polygenic, multitrait basis for serpentine adaptation. Comparing our results to a previous study of independent serpentine colonizations in the closely related diploid Arabidopsis lyrata in the United Kingdom and United States, we find the highest levels of differentiation in 11 of the same loci, providing candidate alleles for mediating convergent evolution. This overlap between independent colonizations in different species suggests that a limited number of evolutionary strategies are suited to overcome the multiple challenges of serpentine adaptation. Interestingly, we detect footprints of selection in A. arenosa in the context of substantial gene flow from nearby off-serpentine populations of A. arenosa, as well as from A. lyrata In several cases, quantitative tests of introgression indicate that some alleles exhibiting strong selective sweep signatures appear to have been introgressed from A. lyrata This finding suggests that migrant alleles may have facilitated adaptation of A. arenosa to this multihazard environment.

  3. Temporal Convergence for Knowledge Management

    Directory of Open Access Journals (Sweden)

    Christopher Phillip Martin

    2008-05-01

    Full Text Available Time and knowledge have tended to be conceptualised in conventional knowledge management systems as either ‘timeless’ recordings of procedures, or time-stamped records of past events and states. The concept of temporal convergence was previously developed to help apply knowledge-management theory to complex military processes such as commander’s intent, shared situation awareness, and self-synchronisation. This paper clarifies the concept and introduces several others in forming a framework to assist discussion and exploration of the types of knowledge required for complex endeavours, such as warfighting, characterised by opposition and uncertainty. The approach is grounded in a pragmatist philosophy and constructivist epistemology. Argument proceeds along mathematical lines from a basis that the types of knowledge most valuable to goal-directed agents in uncertain environments can be modelled as directed graph topologies. The framework is shown to be useful in describing and reasoning about the knowledge requirements and prerequisites for distributed decision-making through the sharing of situational knowledge and common intentions, with practical application to the planning and execution of operations. To the designers of knowledge management systems seeking to address this space, it presents a challenge that cannot be addressed merely by construction, storage, search and retrieval of documents and records pertaining to the past.

  4. Statistical Convergence of Double Sequences of Order

    Directory of Open Access Journals (Sweden)

    R. Çolak

    2013-01-01

    Full Text Available We intend to make a new approach and introduce the concepts of statistical convergence of order and strongly -Cesàro summability of order for double sequences of complex or real numbers. Also, some relations between the statistical convergence of order and strong -Cesàro summability of order are given.

  5. Beyond Brainstorming: Exploring Convergence in Teams

    DEFF Research Database (Denmark)

    Seeber, Isabella; de Vreede, Gert-Jan; Maier, Ronald

    2017-01-01

    Collaborative brainstorming is often followed by a convergence activity where teams extract the most promising ideas on a useful level of detail from the brainstorming results. Contrary to the wealth of research on electronic brainstorming, there is a dearth of research on convergence. We used...

  6. New concurrent iterative methods with monotonic convergence

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Qingchuan [Michigan State Univ., East Lansing, MI (United States)

    1996-12-31

    This paper proposes the new concurrent iterative methods without using any derivatives for finding all zeros of polynomials simultaneously. The new methods are of monotonic convergence for both simple and multiple real-zeros of polynomials and are quadratically convergent. The corresponding accelerated concurrent iterative methods are obtained too. The new methods are good candidates for the application in solving symmetric eigenproblems.

  7. Explaining convergence of oecd welfare states

    DEFF Research Database (Denmark)

    Schmitt, C.; Starke, Peter

    2011-01-01

    of conditional convergence helps to both better describe and explain the phenomenon. By applying error correction models, we examine conditional convergence of various types of social expenditure in 21 OECD countries between 1980 and 2005. Our empirical findings go beyond the existing literature in two respects...

  8. Preasymptotic convergence of randomized Kaczmarz method

    Science.gov (United States)

    Jiao, Yuling; Jin, Bangti; Lu, Xiliang

    2017-12-01

    Kaczmarz method is one popular iterative method for solving inverse problems, especially in computed tomography. Recently, it was established that a randomized version of the method enjoys an exponential convergence for well-posed problems, and the convergence rate is determined by a variant of the condition number. In this work, we analyze the preasymptotic convergence behavior of the randomized Kaczmarz method, and show that the low-frequency error (with respect to the right singular vectors) decays faster during first iterations than the high-frequency error. Under the assumption that the initial error is smooth (e.g. sourcewise representation), the result explains the fast empirical convergence behavior, thereby shedding new insights into the excellent performance of the randomized Kaczmarz method in practice. Further, we propose a simple strategy to stabilize the asymptotic convergence of the iteration by means of variance reduction. We provide extensive numerical experiments to confirm the analysis and to elucidate the behavior of the algorithms.

  9. Instrumental resolution as a function of scattering angle and wavelength as exemplified for the POWGEN instrument.

    Science.gov (United States)

    Jacobs, Philipp; Houben, Andreas; Schweika, Werner; Tchougréeff, Andrei L; Dronskowski, Richard

    2017-06-01

    The method of angular- and wavelength-dispersive (e.g. two-dimensional) Rietveld refinement is a new and emerging tool for the analysis of neutron diffraction data measured at time-of-flight instruments with large area detectors. Following the approach for one-dimensional refinements (using either scattering angle or time of flight), the first step at each beam time cycle is the calibration of the instrument including the determination of instrumental contributions to the peak shape variation to be expected for diffraction patterns measured by the users. The aim of this work is to provide the users with calibration files and - for the later Rietveld refinement of the measured data - with an instrumental resolution file (IRF). This article will elaborate on the necessary steps to generate such an IRF for the angular- and wavelength-dispersive case, exemplified for the POWGEN instrument. A dataset measured on a standard diamond sample is used to extract the profile function in the two-dimensional case. It is found that the variation of reflection width with 2θ and λ can be expressed by the standard equation used for evaluating the instrumental resolution, which yields a substantially more fundamental approach to the parameterization of the instrumental contribution to the peak shape. Geometrical considerations of the POWGEN instrument and sample effects lead to values for Δθ, Δt and ΔL that yield a very good match to the extracted FWHM values. In a final step the refinement results are compared with the one-dimensional, i.e. diffraction-focused, case.

  10. The first and second ‘laws’ of chemical morphology, exemplified in mammalian extracellular matrices

    Directory of Open Access Journals (Sweden)

    JE Scott

    2010-01-01

    Full Text Available Tissues are supramolecular organisations. The permanent and semi-permanent biopolymers therein function collaboratively in specifically bonded frameworks of macromolecules according to the physico-chemical laws that govern the behaviour of all molecules. In this paper two ‘laws’ or principles are discussed which give insights into the development and function of tissues, particularly the extracellular matrices (ECMs of connective tissues. The first ‘law’ is qualitative;- The shape of a tissue is implicit in the shapes of the biopolymers from which it is constructed. The tissue biopolymers are jigsaw pieces, if they don’t fit precisely, there is no picture. The second ‘law’ is quantitative;-The composition of a tissue is determined by the stable, specific interactions between the macromolecules of which it is constructed. These basic ideas underlie the discipline of chemical morphology. The term chemical morphology implies both the chemistry of shape and the shape of chemicals. The first meaning is well exemplified in the ECMs of connective tissues, in which the shape of an organism is defined and maintained. Specific relationships between the fibrillar (collagenous components and the soluble polymers (proteoglycans are set in the context of the first law. Tissue electron histochemistry (the morphology of the tissue and knowledge of secondary and tertiary structures of the participating biopolymers (the shapes of the chemicals together provide a model susceptible to quantitative testing. Simple calculation shows that the amount of any ligand (e.g. a proteoglycan specifically bound at a single binding site per unit of collagen fibril length (the D period increases linearly with the fibril diameter. Given the amount of collagen (measured as hydroxyproline and its density, the constant of proportionality is ~42. Comparisons of the quantitative relationship between collagen and proteoglycans predicted from the model agree well with

  11. Song convergence in multiple urban populations of silvereyes (Zosterops lateralis).

    Science.gov (United States)

    Potvin, Dominique A; Parris, Kirsten M

    2012-08-01

    Recent studies have revealed differences between urban and rural vocalizations of numerous bird species. These differences include frequency shifts, amplitude shifts, altered song speed, and selective meme use. If particular memes sung by urban populations are adapted to the urban soundscape, "urban-typical" calls, memes, or repertoires should be consistently used in multiple urban populations of the same species, regardless of geographic location. We tested whether songs or contact calls of silvereyes (Zosterops lateralis) might be subject to such convergent cultural evolution by comparing syllable repertoires of geographically dispersed urban and rural population pairs throughout southeastern Australia. Despite frequency and tempo differences between urban and rural calls, call repertoires were similar between habitat types. However, certain song syllables were used more frequently by birds from urban than rural populations. Partial redundancy analysis revealed that both geographic location and habitat characteristics were important predictors of syllable repertoire composition. These findings suggest convergent cultural evolution: urban populations modify both song and call syllables from their local repertoire in response to noise.

  12. Phenotypic similarity in sympatric crow species: Evidence of social convergence?

    Science.gov (United States)

    Laiolo, Paola

    2017-04-01

    Crows, rooks, and ravens (Corvus spp.) display marked morphological and voice similarities that have been hypothesized to stem from competitive interactions, as a case of nonaposematic mimicry. Here, I test predictions of the mimicry hypothesis at the macrovolutionary scale, examining whether species morphological and acoustic traits covary with those of coexisting congeners, and whether phenotypic similarity has facilitated the coexistence of related species after secondary contact. Body size and the temporal patterns of the commonest call display high levels of similarity among sympatric species, even after controlling for the effect of shared climate and habitat, and phylogenetic constraints in the production of variation. When sister species differed in these acoustic and morphological traits, their transition to secondary sympatry was delayed relative to those with more similar traits. No similarity was found in the sexual call of crows, suggesting that convergence occurs only when function does not favour maintenance of species-specific traits. Crow similarities in morphological and acoustic features may therefore be associated with coevolving interactions with congeners, in line with a broad array of studies documenting convergence among species that interact aggressively or forage communally. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

  13. Song convergence in multiple urban populations of silvereyes (Zosterops lateralis)

    Science.gov (United States)

    Potvin, Dominique A; Parris, Kirsten M

    2012-01-01

    Recent studies have revealed differences between urban and rural vocalizations of numerous bird species. These differences include frequency shifts, amplitude shifts, altered song speed, and selective meme use. If particular memes sung by urban populations are adapted to the urban soundscape, “urban-typical” calls, memes, or repertoires should be consistently used in multiple urban populations of the same species, regardless of geographic location. We tested whether songs or contact calls of silvereyes (Zosterops lateralis) might be subject to such convergent cultural evolution by comparing syllable repertoires of geographically dispersed urban and rural population pairs throughout southeastern Australia. Despite frequency and tempo differences between urban and rural calls, call repertoires were similar between habitat types. However, certain song syllables were used more frequently by birds from urban than rural populations. Partial redundancy analysis revealed that both geographic location and habitat characteristics were important predictors of syllable repertoire composition. These findings suggest convergent cultural evolution: urban populations modify both song and call syllables from their local repertoire in response to noise. PMID:22957198

  14. On the convergence of finite state mean-field games through Γ-convergence

    KAUST Repository

    Ferreira, Rita C.

    2014-10-01

    In this study, we consider the long-term convergence (trend toward an equilibrium) of finite state mean-field games using Γ-convergence. Our techniques are based on the observation that an important class of mean-field games can be viewed as the Euler-Lagrange equation of a suitable functional. Therefore, using a scaling argument, one can convert a long-term convergence problem into a Γ-convergence problem. Our results generalize previous results related to long-term convergence for finite state problems. © 2014 Elsevier Inc.

  15. Molecular Diversity and Gene Evolution of the Venom Arsenal of Terebridae Predatory Marine Snails.

    Science.gov (United States)

    Gorson, Juliette; Ramrattan, Girish; Verdes, Aida; Wright, Elizabeth M; Kantor, Yuri; Rajaram Srinivasan, Ramakrishnan; Musunuri, Raj; Packer, Daniel; Albano, Gabriel; Qiu, Wei-Gang; Holford, Mandë

    2015-05-28

    Venom peptides from predatory organisms are a resource for investigating evolutionary processes such as adaptive radiation or diversification, and exemplify promising targets for biomedical drug development. Terebridae are an understudied lineage of conoidean snails, which also includes cone snails and turrids. Characterization of cone snail venom peptides, conotoxins, has revealed a cocktail of bioactive compounds used to investigate physiological cellular function, predator-prey interactions, and to develop novel therapeutics. However, venom diversity of other conoidean snails remains poorly understood. The present research applies a venomics approach to characterize novel terebrid venom peptides, teretoxins, from the venom gland transcriptomes of Triplostephanus anilis and Terebra subulata. Next-generation sequencing and de novo assembly identified 139 putative teretoxins that were analyzed for the presence of canonical peptide features as identified in conotoxins. To meet the challenges of de novo assembly, multiple approaches for cross validation of findings were performed to achieve reliable assemblies of venom duct transcriptomes and to obtain a robust portrait of Terebridae venom. Phylogenetic methodology was used to identify 14 teretoxin gene superfamilies for the first time, 13 of which are unique to the Terebridae. Additionally, basic local algorithm search tool homology-based searches to venom-related genes and posttranslational modification enzymes identified a convergence of certain venom proteins, such as actinoporin, commonly found in venoms. This research provides novel insights into venom evolution and recruitment in Conoidean predatory marine snails and identifies a plethora of terebrid venom peptides that can be used to investigate fundamental questions pertaining to gene evolution. © The Author(s) 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  16. Data Convergence - An Australian Perspective

    Science.gov (United States)

    Allen, S. S.; Howell, B.

    2012-12-01

    Coupled numerical physical, biogeochemical and sediment models are increasingly being used as integrators to help understand the cumulative or far field effects of change in the coastal environment. This reliance on modeling has forced observations to be delivered as data streams ingestible by modeling frameworks. This has made it easier to create near real-time or forecasting models than to try to recreate the past, and has lead in turn to the conversion of historical data into data streams to allow them to be ingested by the same frameworks. The model and observation frameworks under development within Australia's Commonwealth and Industrial Research Organisation (CSIRO) are now feeding into the Australian Ocean Data Network's (AODN's) MARine Virtual Laboratory (MARVL) . The sensor, or data stream, brokering solution is centred around the "message" and all data flowing through the gateway is wrapped as a message. Messages consist of a topic and a data object and their routing through the gateway to pre-processors and listeners is determined by the topic. The Sensor Message Gateway (SMG) method is allowing data from different sensors measuring the same thing but with different temporal resolutions, units or spatial coverage to be ingested or visualized seamlessly. At the same time the model output as a virtual sensor is being explored, this again being enabled by the SMG. It is only for two way communications with sensor that rigorous adherence to standards is needed, by accepting existing data in less than ideal formats, but exposing them though the SMG we can move a step closer to the Internet Of Things by creating an Internet of Industries where each vested interest can continue with business as usual, contribute to data convergence and adopt more open standards when investment seems appropriate to that sector or business.Architecture Overview

  17. Which factor dominates the industry evolution? A synergy analysis based on China's ICT industry

    CERN Document Server

    Li, Yaya; Zhao, Yulin; Wang, Fang

    2014-01-01

    Industry evolution caused by various reasons, among which technology progress driving industry development has been approved, but with the new trend of industry convergence, inter-industry convergence also plays an increasing important role. This paper plans to probe the industry synergetic evolution mechanism based on industry convergence and technology progress. Firstly, we use self-organization method and Haken Model to establish synergetic evolution equations, select technology progress and industry convergence as the key variables of industry evolution system; then use patent licensing data of china's listed ICT companies to measure industry convergence rate and apply DEA Malmquist index method to calculate technology progress level; furthermore apply simultaneous equation estimation method to investigate the synergetic industry evolution process. From 2002 to 2012, China's ICT industry develops rapidly; it has the most obvious convergence and powerful technology progress compared with other industries. ...

  18. Overcoming Deception in Evolution of Cognitive Behaviors

    DEFF Research Database (Denmark)

    Lehman, Joel; Miikkulainen, Risto

    2014-01-01

    evolutionary robotics T-Maze domain is adapted in three separate ways to require agents to communicate, remember, and learn. Indicative of deception, evolution driven by objective-based fitness often converges upon simple non- cognitive behaviors. In contrast, evolution driven to explore novel behaviors, i...

  19. Strategic business transformation through technology convergence

    DEFF Research Database (Denmark)

    Agarwal, Nivedita; Brem, Alexander

    2015-01-01

    -time intelligence. This paper presents the case of General Electric (GE) and studies the various transitional phases and transformation dimensions that GE is experiencing, to manage this technology convergence. The evaluation of GE's experience indicates that convergence-related business transformation is nonlinear......Technology adoption is crucial for an organisation to remain competitive in the marketplace. Traditionally, two technologies - operational technology (OT) and information technology (IT) - have operated independently from one another; however, technological advancements that businesses......, and that some dimensions and stages of transformation previously thought to be relevant may not be pertinent for successful business transformations through technology convergence....

  20. Testing Adaptive Hypotheses of Convergence with Functional Landscapes: A Case Study of Bone-Cracking Hypercarnivores

    Science.gov (United States)

    Tseng, Zhijie Jack

    2013-01-01

    Morphological convergence is a well documented phenomenon in mammals, and adaptive explanations are commonly employed to infer similar functions for convergent characteristics. I present a study that adopts aspects of theoretical morphology and engineering optimization to test hypotheses about adaptive convergent evolution. Bone-cracking ecomorphologies in Carnivora were used as a case study. Previous research has shown that skull deepening and widening are major evolutionary patterns in convergent bone-cracking canids and hyaenids. A simple two-dimensional design space, with skull width-to-length and depth-to-length ratios as variables, was used to examine optimized shapes for two functional properties: mechanical advantage (MA) and strain energy (SE). Functionality of theoretical skull shapes was studied using finite element analysis (FEA) and visualized as functional landscapes. The distribution of actual skull shapes in the landscape showed a convergent trend of plesiomorphically low-MA and moderate-SE skulls evolving towards higher-MA and moderate-SE skulls; this is corroborated by FEA of 13 actual specimens. Nevertheless, regions exist in the landscape where high-MA and lower-SE shapes are not represented by existing species; their vacancy is observed even at higher taxonomic levels. Results highlight the interaction of biomechanical and non-biomechanical factors in constraining general skull dimensions to localized functional optima through evolution. PMID:23734244

  1. Testing adaptive hypotheses of convergence with functional landscapes: a case study of bone-cracking hypercarnivores.

    Directory of Open Access Journals (Sweden)

    Zhijie Jack Tseng

    Full Text Available Morphological convergence is a well documented phenomenon in mammals, and adaptive explanations are commonly employed to infer similar functions for convergent characteristics. I present a study that adopts aspects of theoretical morphology and engineering optimization to test hypotheses about adaptive convergent evolution. Bone-cracking ecomorphologies in Carnivora were used as a case study. Previous research has shown that skull deepening and widening are major evolutionary patterns in convergent bone-cracking canids and hyaenids. A simple two-dimensional design space, with skull width-to-length and depth-to-length ratios as variables, was used to examine optimized shapes for two functional properties: mechanical advantage (MA and strain energy (SE. Functionality of theoretical skull shapes was studied using finite element analysis (FEA and visualized as functional landscapes. The distribution of actual skull shapes in the landscape showed a convergent trend of plesiomorphically low-MA and moderate-SE skulls evolving towards higher-MA and moderate-SE skulls; this is corroborated by FEA of 13 actual specimens. Nevertheless, regions exist in the landscape where high-MA and lower-SE shapes are not represented by existing species; their vacancy is observed even at higher taxonomic levels. Results highlight the interaction of biomechanical and non-biomechanical factors in constraining general skull dimensions to localized functional optima through evolution.

  2. Testing adaptive hypotheses of convergence with functional landscapes: a case study of bone-cracking hypercarnivores.

    Science.gov (United States)

    Tseng, Zhijie Jack

    2013-01-01

    Morphological convergence is a well documented phenomenon in mammals, and adaptive explanations are commonly employed to infer similar functions for convergent characteristics. I present a study that adopts aspects of theoretical morphology and engineering optimization to test hypotheses about adaptive convergent evolution. Bone-cracking ecomorphologies in Carnivora were used as a case study. Previous research has shown that skull deepening and widening are major evolutionary patterns in convergent bone-cracking canids and hyaenids. A simple two-dimensional design space, with skull width-to-length and depth-to-length ratios as variables, was used to examine optimized shapes for two functional properties: mechanical advantage (MA) and strain energy (SE). Functionality of theoretical skull shapes was studied using finite element analysis (FEA) and visualized as functional landscapes. The distribution of actual skull shapes in the landscape showed a convergent trend of plesiomorphically low-MA and moderate-SE skulls evolving towards higher-MA and moderate-SE skulls; this is corroborated by FEA of 13 actual specimens. Nevertheless, regions exist in the landscape where high-MA and lower-SE shapes are not represented by existing species; their vacancy is observed even at higher taxonomic levels. Results highlight the interaction of biomechanical and non-biomechanical factors in constraining general skull dimensions to localized functional optima through evolution.

  3. Convergence of scalar-tensor theories towards general relativity and primordial nucleosynthesis

    CERN Document Server

    Serna, A; Navarro, A

    2002-01-01

    In this paper, we analyse the conditions for convergence towards general relativity of scalar-tensor gravity theories defined by an arbitrary coupling function alpha (in the Einstein frame). We show that, in general, the evolution of the scalar field (phi) is governed by two opposite mechanisms: an attraction mechanism which tends to drive scalar-tensor models towards Einstein's theory, and a repulsion mechanism which has the contrary effect. The attraction mechanism dominates the recent epochs of the universe evolution if, and only if, the scalar field and its derivative satisfy certain boundary conditions. Since these conditions for convergence towards general relativity depend on the particular scalar-tensor theory used to describe the universe evolution, the nucleosynthesis bounds on the present value of the coupling function, alpha sub 0 , strongly differ from some theories to others. For example, in theories defined by alpha propor to |phi| analytical estimates lead to very stringent nucleosynthesis bou...

  4. A multi-stage 3-D stress field modelling approach exemplified in the Bavarian Molasse Basin

    Science.gov (United States)

    Ziegler, Moritz O.; Heidbach, Oliver; Reinecker, John; Przybycin, Anna M.; Scheck-Wenderoth, Magdalena

    2016-09-01

    The knowledge of the contemporary in situ stress state is a key issue for safe and sustainable subsurface engineering. However, information on the orientation and magnitudes of the stress state is limited and often not available for the areas of interest. Therefore 3-D geomechanical-numerical modelling is used to estimate the in situ stress state and the distance of faults from failure for application in subsurface engineering. The main challenge in this approach is to bridge the gap in scale between the widely scattered data used for calibration of the model and the high resolution in the target area required for the application. We present a multi-stage 3-D geomechanical-numerical approach which provides a state-of-the-art model of the stress field for a reservoir-scale area from widely scattered data records. Therefore, we first use a large-scale regional model which is calibrated by available stress data and provides the full 3-D stress tensor at discrete points in the entire model volume. The modelled stress state is used subsequently for the calibration of a smaller-scale model located within the large-scale model in an area without any observed stress data records. We exemplify this approach with two-stages for the area around Munich in the German Molasse Basin. As an example of application, we estimate the scalar values for slip tendency and fracture potential from the model results as measures for the criticality of fault reactivation in the reservoir-scale model. The modelling results show that variations due to uncertainties in the input data are mainly introduced by the uncertain material properties and missing SHmax magnitude estimates needed for a more reliable model calibration. This leads to the conclusion that at this stage the model's reliability depends only on the amount and quality of available stress information rather than on the modelling technique itself or on local details of the model geometry. Any improvements in modelling and increases

  5. Cultivate technology convergence for product innovation.

    Science.gov (United States)

    Wilkinson, J Malcolm

    2006-04-01

    Technologies from diverse scientific disciplines are being combined to drive innovation in medical devices. How technology convergence and innovation could be further stimulated is explored here using developments in imaging and point-of-care devices as examples.

  6. International Convergence of Accounting Standards: Issues and ...

    African Journals Online (AJOL)

    Unarguably, globalization has become a key driver of the increasing integration and synergy among countries, systems and standards. Consequently, the clamor for ... the Nigerian environment. Keywords: Accounting, international financial reporting standards (IFRS), market liquidity, convergence, institutional setting.

  7. Further remarks on convergence of decomposition method.

    Science.gov (United States)

    Cherruault, Y; Adomian, G; Abbaoui, K; Rach, R

    1995-01-01

    The decomposition method solves a wide class of nonlinear functional equations. This method uses a series solution with rapid convergence. This paper is intended as a useful review and clarification of related issues.

  8. (Crime Victims’ Compensation: The Emergence of Convergence

    Directory of Open Access Journals (Sweden)

    Renée S.B. Kool

    2014-07-01

    Full Text Available Crime victims’ compensation has become a major issue within Dutch criminal policy. Legal procedures have been subject to change, leading towards the convergence of tort law and criminal law. Such a convergence calls for a reflection (on the application of the core concepts of responsibility, accountability and liability. Moreover, the current pursuit of victims’ compensation affects procedural issues, specifically with regard to the issue of enforcement. Leaving aside the issue of the legitimacy of victims’ compensation, this convergence raises the question of how to preserve the delicate balance that flows from the use of the law as an instrument to preserve social order. The topical question is not whether convergence is occurring, but how we must deal with it in order to find a (new equilibrium between the public interest and the interest of the individual who has experienced a harmful wrong.

  9. Impact of fixed-mobile convergence

    DEFF Research Database (Denmark)

    Pachnicke, Stephan; Andrus, Bogdan-Mihai; Autenrieth, Achim

    2016-01-01

    Fixed-Mobile Convergence (FMC) is a very trendy concept as it promises integration of the previously separated fixed access network and the mobile network. From this novel approach telecommunication operators expect significant cost savings and performance improvements. FMC can be separated...... into structural convergence (regarding the infrastructure) and functional convergence (regarding the necessary functionalities required in fixed and mobile networks). The latter one goes hand-in-hand with Network Function Virtualization (NFV), where important network functions are provided by a server inside...... of the next generation point-of-presence (NG-POP). In this article implications on the system architecture as well as structural and functional convergence topics will be discussed....

  10. Divergence and convergence in nutrition science

    NARCIS (Netherlands)

    Penders, Bart; Spruit, Shannon L.; Sikkema, Jan; Maat, Jan; Schuurbiers, Daan

    2015-01-01

    Nutrigenomics diverged from mainstream nutrition science, ideologically, instrumentally and culturally, due to the establishment of a protective niche. That protection is fading. This article chronicles a case in which convergence between nutrigenomics and nutrition science is pursued. Here we

  11. Modes of convergence for term graph rewriting

    DEFF Research Database (Denmark)

    Bahr, Patrick

    2012-01-01

    Term graph rewriting provides a simple mechanism to finitely represent restricted forms of infinitary term rewriting. The correspondence between infinitary term rewriting and term graph rewriting has been studied to some extent. However, this endeavour is impaired by the lack of an appropriate...... counterpart of infinitary rewriting on the side of term graphs. We aim to fill this gap by devising two modes of convergence based on a partial order respectively a metric on term graphs. The thus obtained structures generalise corresponding modes of convergence that are usually studied in infinitary term...... rewriting. We argue that this yields a common framework in which both term rewriting and term graph rewriting can be studied. In order to substantiate our claim, we compare convergence on term graphs and on terms. In particular, we show that the modes of convergence on term graphs are conservative...

  12. Convergence of Attitudes among College Students

    Science.gov (United States)

    Whatley, Alice E.; Appel, Victor H.

    1973-01-01

    Attempts to determine whether the intersex convergence phenomenon could be applicable to the measured attitudes of collegiate samples. Both sexes seemed to be moving toward a more liberal view on issues related to marriage and the family. (Author)

  13. On Paranorm Zweier -Convergent Sequence Spaces

    Directory of Open Access Journals (Sweden)

    Vakeel A. Khan

    2013-01-01

    Full Text Available In this paper, we introduce the paranorm Zweier -convergent sequence spaces , , and , a sequence of positive real numbers. We study some topological properties, prove the decomposition theorem, and study some inclusion relations on these spaces.

  14. Statistical convergence, selection principles and asymptotic analysis

    Energy Technology Data Exchange (ETDEWEB)

    Di Maio, G. [Dipartimento di Matematica, Seconda Universita di Napoli, Via Vivaldi 43, 81100 Caserta (Italy)], E-mail: giuseppe.dimaio@unina2.it; Djurcic, D. [Technical Faculty, University of Kragujevac, Svetog Save 65, 32000 Cacak (Serbia)], E-mail: dragandj@tfc.kg.ac.yu; Kocinac, Lj.D.R. [Faculty of Sciences and Mathematics, University of Nis, Visegradska 33, 18000 Nis (Serbia)], E-mail: lkocinac@ptt.rs; Zizovic, M.R. [Technical Faculty, University of Kragujevac, Svetog Save 65, 32000 Cacak (Serbia)], E-mail: zizo@tfc.kg.ac.yu

    2009-12-15

    We consider the set S of sequences of positive real numbers in the context of statistical convergence/divergence and show that some subclasses of S have certain nice selection and game-theoretic properties.

  15. Gene loss, adaptive evolution and the co-evolution of plumage coloration genes with opsins in birds.

    Science.gov (United States)

    Borges, Rui; Khan, Imran; Johnson, Warren E; Gilbert, M Thomas P; Zhang, Guojie; Jarvis, Erich D; O'Brien, Stephen J; Antunes, Agostinho

    2015-10-06

    The wide range of complex photic systems observed in birds exemplifies one of their key evolutionary adaptions, a well-developed visual system. However, genomic approaches have yet to be used to disentangle the evolutionary mechanisms that govern evolution of avian visual systems. We performed comparative genomic analyses across 48 avian genomes that span extant bird phylogenetic diversity to assess evolutionary changes in the 17 representatives of the opsin gene family and five plumage coloration genes. Our analyses suggest modern birds have maintained a repertoire of up to 15 opsins. Synteny analyses indicate that PARA and PARIE pineal opsins were lost, probably in conjunction with the degeneration of the parietal organ. Eleven of the 15 avian opsins evolved in a non-neutral pattern, confirming the adaptive importance of vision in birds. Visual conopsins sw1, sw2 and lw evolved under negative selection, while the dim-light RH1 photopigment diversified. The evolutionary patterns of sw1 and of violet/ultraviolet sensitivity in birds suggest that avian ancestors had violet-sensitive vision. Additionally, we demonstrate an adaptive association between the RH2 opsin and the MC1R plumage color gene, suggesting that plumage coloration has been photic mediated. At the intra-avian level we observed some unique adaptive patterns. For example, barn owl showed early signs of pseudogenization in RH2, perhaps in response to nocturnal behavior, and penguins had amino acid deletions in RH2 sites responsible for the red shift and retinal binding. These patterns in the barn owl and penguins were convergent with adaptive strategies in nocturnal and aquatic mammals, respectively. We conclude that birds have evolved diverse opsin adaptations through gene loss, adaptive selection and coevolution with plumage coloration, and that differentiated selective patterns at the species level suggest novel photic pressures to influence evolutionary patterns of more-recent lineages.

  16. Convergence of Corporate and Information Security

    OpenAIRE

    Syed (Shawon) M. Rahman; Shannon E. Donahue,

    2010-01-01

    As physical and information security boundaries have become increasingly blurry many organizations are experiencing challenges with how to effectively and efficiently manage security within the corporate. There is no current standard or best practice offered by the security community regarding convergence; however many organizations such as the Alliance for Enterprise Security Risk Management (AESRM) offer some excellent suggestions for integrating a converged security program. This paper rep...

  17. Global Convergence of a Modified LS Method

    Directory of Open Access Journals (Sweden)

    Liu JinKui

    2012-01-01

    Full Text Available The LS method is one of the effective conjugate gradient methods in solving the unconstrained optimization problems. The paper presents a modified LS method on the basis of the famous LS method and proves the strong global convergence for the uniformly convex functions and the global convergence for general functions under the strong Wolfe line search. The numerical experiments show that the modified LS method is very effective in practice.

  18. Larger Convergence Zones for Newton's Method

    Science.gov (United States)

    Campbell, C. W.

    1986-01-01

    Iterative technique applies over wider range of initial guesses. New theorem describes convergence zone of Newton's iterative method for finding zeros of real function. Involves two points, Xp and Xp*, called primary conjugate points. If exact solution lies between these points (Xp is less than Xz is less than Xp*) and no other conjugate points in interval, then according to theorem, subsequent iterations will converge upon exact solution if initial guess lies in interval.

  19. Trophic divergence despite morphological convergence in a continental radiation of snakes.

    Science.gov (United States)

    Grundler, Michael C; Rabosky, Daniel L

    2014-07-22

    Ecological and phenotypic convergence is a potential outcome of adaptive radiation in response to ecological opportunity. However, a number of factors may limit convergence during evolutionary radiations, including interregional differences in biogeographic history and clade-specific constraints on form and function. Here, we demonstrate that a single clade of terrestrial snakes from Australia--the oxyuranine elapids--exhibits widespread morphological convergence with a phylogenetically diverse and distantly related assemblage of snakes from North America. Australian elapids have evolved nearly the full spectrum of phenotypic modalities that occurs among North American snakes. Much of the convergence appears to involve the recurrent evolution of stereotyped morphologies associated with foraging mode, locomotion and habitat use. By contrast, analysis of snake diets indicates striking divergence in feeding ecology between these faunas, partially reflecting regional differences in ecological allometry between Australia and North America. Widespread phenotypic convergence with the North American snake fauna coupled with divergence in feeding ecology are clear examples of how independent continental radiations may converge along some ecological axes yet differ profoundly along others. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  20. Fixing convergence of Gaussian belief propagation

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Jason K [Los Alamos National Laboratory; Bickson, Danny [IBM RESEARCH LAB; Dolev, Danny [HEBREW UNIV

    2009-01-01

    Gaussian belief propagation (GaBP) is an iterative message-passing algorithm for inference in Gaussian graphical models. It is known that when GaBP converges it converges to the correct MAP estimate of the Gaussian random vector and simple sufficient conditions for its convergence have been established. In this paper we develop a double-loop algorithm for forcing convergence of GaBP. Our method computes the correct MAP estimate even in cases where standard GaBP would not have converged. We further extend this construction to compute least-squares solutions of over-constrained linear systems. We believe that our construction has numerous applications, since the GaBP algorithm is linked to solution of linear systems of equations, which is a fundamental problem in computer science and engineering. As a case study, we discuss the linear detection problem. We show that using our new construction, we are able to force convergence of Montanari's linear detection algorithm, in cases where it would originally fail. As a consequence, we are able to increase significantly the number of users that can transmit concurrently.

  1. Local convergence of a fifth convergence order method in Banach space

    Directory of Open Access Journals (Sweden)

    Ioannis K. Argyros

    2017-07-01

    Full Text Available We provide a local convergence analysis for a fifth convergence order method to find a solution of a nonlinear equation in a Banach space. In our paper the sufficient convergence conditions involve only hypotheses on the first Fréchet-derivative. Previous works use conditions reaching up to the fourth Fréchet-derivative. This way, the applicability of these methods is extended under weaker conditions and less computational cost for the Lipschitz constants appearing in the convergence analysis. Numerical examples are also given in this paper.

  2. Polycystin-1 binds Par3/aPKC and controls convergent extension during renal tubular morphogenesis

    Science.gov (United States)

    Castelli, Maddalena; Boca, Manila; Chiaravalli, Marco; Ramalingam, Harini; Rowe, Isaline; Distefano, Gianfranco; Carroll, Thomas; Boletta, Alessandra

    2013-10-01

    Several organs, including the lungs and kidneys, are formed by epithelial tubes whose proper morphogenesis ensures correct function. This is best exemplified by the kidney, where defective establishment or maintenance of tubular diameter results in polycystic kidney disease, a common genetic disorder. Most polycystic kidney disease cases result from loss-of-function mutations in the PKD1 gene, encoding Polycystin-1, a large receptor of unknown function. Here we demonstrate that PC-1 has an essential role in the establishment of correct tubular diameter during nephron development. Polycystin-1 associates with Par3 favouring the assembly of a pro-polarizing Par3/aPKC complex and it regulates a programme of cell polarity important for oriented cell migration and for a convergent extension-like process during tubular morphogenesis. Par3 inactivation in the developing kidney results in defective convergent extension and tubular morphogenesis, and in renal cyst formation. Our data define Polycystin-1 as central to cell polarization and to epithelial tube morphogenesis and homeostasis.

  3. Possibilities for global governance of converging technologies

    Science.gov (United States)

    Roco, Mihail C.

    2008-01-01

    The convergence of nanotechnology, modern biology, the digital revolution and cognitive sciences will bring about tremendous improvements in transformative tools, generate new products and services, enable opportunities to meet and enhance human potential and social achievements, and in time reshape societal relationships. This paper focuses on the progress made in governance of such converging, emerging technologies and suggests possibilities for a global approach. Specifically, this paper suggests creating a multidisciplinary forum or a consultative coordinating group with members from various countries to address globally governance of converging, emerging technologies. The proposed framework for governance of converging technologies calls for four key functions: supporting the transformative impact of the new technologies; advancing responsible development that includes health, safety and ethical concerns; encouraging national and global partnerships; and establishing commitments to long-term planning and investments centered on human development. Principles of good governance guiding these functions include participation of all those who are forging or affected by the new technologies, transparency of governance strategies, responsibility of each participating stakeholder, and effective strategic planning. Introduction and management of converging technologies must be done with respect for immediate concerns, such as privacy, access to medical advancements, and potential human health effects. At the same time, introduction and management should also be done with respect for longer-term concerns, such as preserving human integrity, dignity and welfare. The suggested governance functions apply to four levels of governance: (a) adapting existing regulations and organizations; (b) establishing new programs, regulations and organizations specifically to handle converging technologies; (c) building capacity for addressing these issues into national policies and

  4. Reduced convergence within the Tibetan Plateau by 26 Ma?

    Science.gov (United States)

    Meng, Jun; Coe, Robert S.; Wang, Chengshan; Gilder, Stuart A.; Zhao, Xixi; Liu, Hao; Li, Yalin; Ma, Pengfei; Shi, Kai; Li, Shuai

    2017-07-01

    Understanding the dynamics of double-thickening and uplifting of the Tibetan crust requires constraints on the magnitude and timing of crustal shortening. New elongation/inclination (E/I)-corrected paleomagnetic data from 26-22 Ma sediments indicate that the latitude of southern Tibet in the early Miocene was 31.1/-6.8/+5.2°N, not significantly different from today. This implies that the southern margin of Asia, which was at 21-24°N latitude from the Late Cretaceous to the early Eocene, advanced 8-10° northward between the early Eocene and the latest Oligocene. Our results therefore suggest that at least 900-1100 km of continental shortening and significant regional uplift of the plateau occurred between the early Eocene and late Oligocene. Our results suggest that N-S intra-Asian convergence was considerably reduced around 26 Ma, corresponding to a transition from compression to extension within the Tibetan Plateau.type="synopsis">type="main">Plain Language SummaryTwo critical questions involving the geodynamic evolution of the Tibetan plateau are (i) when did a compression-dominated tectonic regime change to an extension-dominated tectonic regime on the plateau and (ii) how does this timing correlate with double thickening of the crust? Here we provide paleomagnetic evidence for the timing, magnitude, and partitioning of intra-Asian convergence. Our results imply a first-order constraint of 900-1100 km north-south shortening concentrated within the interval from 53 to 26 Ma. This suggests that a fundamental change at 26 Ma occurred in the geodynamics of the Tibetan Plateau marked by a reduction in large-scale convergence and compressive deformation. The implication is that significant regional uplift of the proto-Tibetan Plateau occurred within the 55-26 Ma interval. The paleolatitude, paleoclimate, and topography of south central Tibet seen at present were likely established around 26 Ma.

  5. Binocularity and brain evolution in primates

    OpenAIRE

    Barton, R. A.

    2004-01-01

    Primates are distinguished by frontally directed, highly convergent orbits, which are associated with stereoscopic vision. Although stereoscopic vision requires specialized neural mechanisms, its implications for brain evolution are unknown. Using phylogenetic comparative analysis, I show that evolutionary increases among primate taxa in the degree of orbital convergence correlate with expansion of visual brain structures and, as a consequence, with the overall size of the brain. This pattern...

  6. The evolution of the brain in Canidae (Mammalia: Carnivora)

    NARCIS (Netherlands)

    Lyras, G.A.

    2009-01-01

    Canid brain evolution followed three independent, yet convergent paths. Each of the three canid subfamilies (Hesperocyoninae, Borophaginae and Caninae) started with a simple brain, which gradually became more complicated as the cerebral cortex became larger and more fissured, the cerebellar

  7. The Evolution of Health Care Advance Planning Law and Policy

    National Research Council Canada - National Science Library

    CHARLES P. SABATINO

    2010-01-01

    ... with important points of convergence evolving over time. An understanding of the evolution of advance care planning policy has important implications for policy at both the state and federal levels. Methods...

  8. Zipf rank approach and cross-country convergence of incomes

    Science.gov (United States)

    Shao, Jia; Ivanov, Plamen Ch.; Urošević, Branko; Stanley, H. Eugene; Podobnik, Boris

    2011-05-01

    We employ a concept popular in physics —the Zipf rank approach— in order to estimate the number of years that EU members would need in order to achieve "convergence" of their per capita incomes. Assuming that trends in the past twenty years continue to hold in the future, we find that after t≈30 years both developing and developed EU countries indexed by i will have comparable values of their per capita gross domestic product {\\cal G}_{i,t} . Besides the traditional Zipf rank approach we also propose a weighted Zipf rank method. In contrast to the EU block, on the world level the Zipf rank approach shows that, between 1960 and 2009, cross-country income differences increased over time. For a brief period during the 2007-2008 global economic crisis, at world level the {\\cal G}_{i,t} of richer countries declined more rapidly than the {\\cal G}_{i,t} of poorer countries, in contrast to EU where the {\\cal G}_{i,t} of developing EU countries declined faster than the {\\cal G}_{i,t} of developed EU countries, indicating that the recession interrupted the convergence between EU members. We propose a simple model of GDP evolution that accounts for the scaling we observe in the data.

  9. Investigation of Surface Phenomena in Shocked Tin in Converging Geometry

    Energy Technology Data Exchange (ETDEWEB)

    Rousculp, Christopher L. [Los Alamos National Laboratory; Oro, David Michael [Los Alamos National Laboratory; Griego, Jeffrey Randall [Los Alamos National Laboratory; Turchi, Peter John [Los Alamos National Laboratory; Reinovsky, Robert Emil [Los Alamos National Laboratory; Bradley, Joseph Thomas [Los Alamos National Laboratory; Cheng, Baolian [Los Alamos National Laboratory; Freeman, Matthew Stouten [Los Alamos National Laboratory; Patten, Austin Randall [Los Alamos National Laboratory

    2016-03-21

    There is great interest in the behavior of the free surface of tin under shock loading. While it is known that meso-scale surface imperfections can seed the Richtmyer- Meshkov Instability (RMI) for a surface that is melted on release, much less is known about a tin surface that is solid, but plastically deforming. Here material properties such as shear and yield strength come into play especially in converging geometry. Previous experiments have been driven by direct contact HE. Usually a thin, flat target coupon is fielded with various single-mode, sinusoidal, machined, profiles on the free surface. The free surface is adjacent to either vacuum or an inert receiver gas. Most of these previous driver/target configurations have been nominal planer geometry. With modern HE it has been straightforward to shock tin into melt on release. However it has been challenging to achieve a low enough pressure for solid state on release. Here we propose to extend the existing base of knowledge to include the behavior of the free surface of tin in cylindrical converging geometry. By shock loading a cylindrical tin shell with a magnetically driven cylindrical liner impactor, the free surface evolution can be diagnosed with proton radiography. With the PHELIX capacitor bank, the drive can easily be varied to span the pressure range to achieve solid, mixed, and liquid states on release. A conceptual cylindrical liner and target is shown in Figure 1.

  10. Investigation of Surface Phenomena in Shocked Tin in Converging Geometry

    Energy Technology Data Exchange (ETDEWEB)

    Rousculp, Christopher L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Oro, David Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Margolin, Len G. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Griego, Jeffrey Randall [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Reinovsky, Robert Emil [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Turchi, Peter John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-08-06

    There is great interest in the behavior of the free surface of tin under shock loading. While it is known that meso-scale surface imperfections can seed the Richtmyer-Meshkov Instability (RMI) for a surface that is melted on release, much less is known about a tin surface that is solid, but plastically deforming. Here material properties such as shear and yield strength come into play especially in converging geometry. Previous experiments have been driven by direct contact HE. Usually a thin, flat target coupon is fielded with various single-mode, sinusoidal, machined, profiles on the free surface. The free surface is adjacent to either vacuum or an inert receiver gas. Most of these previous driver/target configurations have been nominal planer geometry. With modern HE it has been straightforward to shock tin into melt on release. However it has been challenging to achieve a low enough pressure for solid state on release. Here we propose to extend the existing base of knowledge to include the behavior of the free surface of tin in cylindrical converging geometry. By shock loading a cylindrical tin shell with a magnetically driven cylindrical liner impactor, the free surface evolution can be diagnosed with proton radiography. With the PHELIX capacitor bank, the drive can easily be varied to span the pressure range to achieve solid, mixed, and liquid states on release.

  11. Experimental and numerical analysis of convergent nozzlex

    Science.gov (United States)

    Srinivas, G.; Rakham, Bhupal

    2017-05-01

    In this paper the main focus was given to convergent nozzle where both the experimental and numerical calculations were carried out with the support of standardized literature. In the recent years the field of air breathing and non-air breathing engine developments significantly increase its performance. To enhance the performance of both the type of engines the nozzle is the one of the component which will play a vital role, especially selecting the type of nozzle depends upon the vehicle speed requirement and aerodynamic behavior at most important in the field of propulsion. The convergent nozzle flow experimental analysis done using scaled apparatus and the similar setup was arranged artificially in the ANSYS software for doing the flow analysis across the convergent nozzle. The consistent calculation analysis are done based on the public literature survey to validate the experimental and numerical simulation results of convergent nozzle. Using these two experimental and numerical simulation approaches the best fit results will bring up to meet the design requirements. However the comparison also made to meet the reliability of the work on design criteria of convergent nozzle which can entrench in the field of propulsion applications.

  12. Wave-induced bottom shear stress estimation in shallow water exemplified by using deep water wind statistics

    Directory of Open Access Journals (Sweden)

    Dag Myrhaug

    2017-04-01

    Full Text Available The paper provides a simple and analytical method which can be used to give estimates of the wave-induced bottom shear stress for very rough beds and mud beds in shallow water based on wind statistics in deep water. This is exemplified by using long-term wind statistics from the northern North Sea, and by providing examples representing realistic field conditions. Based on, for example, global wind statistics, the present results can be used to make estimates of the bottom shear stress in shallow water.

  13. Complete Moment Convergence and Mean Convergence for Arrays of Rowwise Extended Negatively Dependent Random Variables

    Directory of Open Access Journals (Sweden)

    Yongfeng Wu

    2014-01-01

    Full Text Available The authors first present a Rosenthal inequality for sequence of extended negatively dependent (END random variables. By means of the Rosenthal inequality, the authors obtain some complete moment convergence and mean convergence results for arrays of rowwise END random variables. The results in this paper extend and improve the corresponding theorems by Hu and Taylor (1997.

  14. Science and technology convergence: with emphasis for nanotechnology-inspired convergence

    Energy Technology Data Exchange (ETDEWEB)

    Bainbridge, William S.; Roco, Mihail C., E-mail: mroco@nsf.gov [National Science Foundation (United States)

    2016-07-15

    Convergence offers a new universe of discovery, innovation, and application opportunities through specific theories, principles, and methods to be implemented in research, education, production, and other societal activities. Using a holistic approach with shared goals, convergence seeks to transcend existing human limitations to achieve improved conditions for work, learning, aging, physical, and cognitive wellness. This paper outlines ten key theories that offer complementary perspectives on this complex dynamic. Principles and methods are proposed to facilitate and enhance science and technology convergence. Several convergence success stories in the first part of the 21st century—including nanotechnology and other emerging technologies—are discussed in parallel with case studies focused on the future. The formulation of relevant theories, principles, and methods aims at establishing the convergence science.

  15. Science and technology convergence: with emphasis for nanotechnology-inspired convergence

    Science.gov (United States)

    Bainbridge, William S.; Roco, Mihail C.

    2016-07-01

    Convergence offers a new universe of discovery, innovation, and application opportunities through specific theories, principles, and methods to be implemented in research, education, production, and other societal activities. Using a holistic approach with shared goals, convergence seeks to transcend existing human limitations to achieve improved conditions for work, learning, aging, physical, and cognitive wellness. This paper outlines ten key theories that offer complementary perspectives on this complex dynamic. Principles and methods are proposed to facilitate and enhance science and technology convergence. Several convergence success stories in the first part of the 21st century—including nanotechnology and other emerging technologies—are discussed in parallel with case studies focused on the future. The formulation of relevant theories, principles, and methods aims at establishing the convergence science.

  16. EVALUATION OF ECONOMIC CONVERGENCE IN ROMANIA

    Directory of Open Access Journals (Sweden)

    CUCO PAULA – ROXANA,

    2016-10-01

    Full Text Available This article aims to highlight the process of regional convergence (regarding income wage per capita or on the contrary, the process of regional divergence, between the 42 counties as reference territorial units in Romania, within the period 2005-2014. In the econometric analyze, the models that were developed had the aim to assess the role of macroeconomic determinants on the average net income per capita, exactly the possibility of a more dynamic growth of wages in poorer counties. The results showed a clear trend towards wage convergence, under the impact of multidimensional factors of influence. Our findings confirm the literature on regional convergence, pointing out the importance of economic development level, quality of human capital, technical progress and intensity of innovation activity, improving labor market integration and even a dynamic entrepreneurial activity.

  17. Mnemonic convergence in the human hippocampus.

    Science.gov (United States)

    Backus, Alexander R; Bosch, Sander E; Ekman, Matthias; Grabovetsky, Alejandro Vicente; Doeller, Christian F

    2016-06-21

    The ability to form associations between a multitude of events is the hallmark of episodic memory. Computational models have espoused the importance of the hippocampus as convergence zone, binding different aspects of an episode into a coherent representation, by integrating information from multiple brain regions. However, evidence for this long-held hypothesis is limited, since previous work has largely focused on representational and network properties of the hippocampus in isolation. Here we identify the hippocampus as mnemonic convergence zone, using a combination of multivariate pattern and graph-theoretical network analyses of functional magnetic resonance imaging data from humans performing an associative memory task. We observe overlap of conjunctive coding and hub-like network attributes in the hippocampus. These results provide evidence for mnemonic convergence in the hippocampus, underlying the integration of distributed information into episodic memory representations.

  18. Plurality or convergence in sustainability reporting standards?

    Directory of Open Access Journals (Sweden)

    Nadia Albu

    2013-11-01

    Full Text Available Over the last years an increasing number of companies issued Corporate Social Responsibility (CSR or Sustainability Reports to complement their traditional financial reporting. Companies use various sustainability reporting standards or develop their own reporting frameworks starting from the existing ones. This variation of practices pointed out by empirical research raises questions about the quality and comparability of sustainability reporting, its role in the sustainable development, and also about the suitability of accepting the plurality of reporting frameworks or the need for convergence. This study aims to investigate the issues of plurality and convergence in sustainability reporting standards, by mobilizing the discourses on regulation and the case of a group of companies in the IT industry in order to shed some light on the current challenges in this area. We frame a discussion on the opportunities and pitfalls of convergence in sustainability reporting regulations and contribute to a better understanding of this issue by academics, preparers, users and standard setters

  19. Modes of convergence for term graph rewriting

    DEFF Research Database (Denmark)

    Bahr, Patrick

    2011-01-01

    Term graph rewriting provides a simple mechanism to finitely represent restricted forms of infinitary term rewriting. The correspondence between infinitary term rewriting and term graph rewriting has been studied to some extent. However, this endeavour is impaired by the lack of an appropriate...... counterpart of infinitary rewriting on the side of term graphs. We aim to fill this gap by devising two modes of convergence based on a partial order resp. a metric on term graphs. The thus obtained structures generalise corresponding modes of convergence that are usually studied in infinitary term rewriting....... We argue that this yields a common framework in which both term rewriting and term graph rewriting can be studied. In order to substantiate our claim, we compare convergence on term graphs and on terms. In particular, we show that the resulting infinitary calculi of term graph rewriting exhibit...

  20. Divergence and Convergence in Education and Work

    DEFF Research Database (Denmark)

    Are the educational systems in Europe becoming more similar or more different? This book deals with the issue ofdivergence and convergence in relation to systems, learning environments, and learners in vocational educational training (VET). 18 VET researchers from eight countries contribute...... training in the formation of biographies and identities.The book thus covers the central issues on the agenda in relation to future vocational education....... to the examination of 'divergence and convergence' at three levels: At the national level this volume deals with the following questions: What are the consequences of the European policies that aim at converging the VET systems in Europe? What is the impact of globalization on the national systems? At the level...

  1. Convergence of coupled cluster perturbation theory

    CERN Document Server

    Eriksen, Janus Juul; Matthews, Devin A; Jørgensen, Poul; Olsen, Jeppe

    2016-01-01

    The convergence of a recently proposed coupled cluster (CC) family of perturbation series [Eriksen et al., J. Chem. Phys. 140, 064108 (2014)], in which the energetic difference between a parent and a target CC model is expanded in orders of the M{\\o}ller-Plesset (MP) fluctuation potential, is investigated for four prototypical closed-shell systems (Ne, singlet methylene, distorted HF, and the fluoride anion) in standard and augmented basis sets. In these investigations, energy corrections of the various series have been calculated to high orders and their convergence radii determined by probing for possible front- and back-door intruder states. In summary, we conclude how it is primarily the choice of target state, and not the choice of parent state, which ultimately governs the convergence behavior of a given series. For example, restricting the target state to, say, triple or quadruple excitations might remove intruders present in series that target the full configuration interaction (FCI) limit, such as th...

  2. Order convergence structure on C(X) | Anguelov | Quaestiones ...

    African Journals Online (AJOL)

    This paper brings together three concepts which have not been related so far, namely, the concept of order convergence, the concept of convergence space and the concept of Hausdorff continuous functions. The order convergence on a poset P, which is generally not a topological convergence, can be studied through the ...

  3. Extension Stakeholder Engagement: An Exploration of Two Cases Exemplifying 21st Century Adaptions

    Directory of Open Access Journals (Sweden)

    Charles French

    2015-06-01

    Full Text Available Over the past 100 years, a number of societal trends have influenced how Cooperative Extension engages public audiences in its outreach and education efforts. These trends include rapid evolution in communication technology, greater specialization of Land-Grant University faculty, and diversification of funding sources. In response, Extension organizations have adapted their engagement approach, incorporated new technologies, modified their organizational structures, and even expanded the notion of public stakeholders to include funders, program nonparticipants, and others. This article explores the implications for future Extension efforts using two case studies—one which explores how a community visioning program incorporated new ways of engaging local audiences, and another which explores how an Extension business retention program used participatory action research and educational organizing approaches to strengthen participation in a research-based program.

  4. Specialisation and Convergence in European Regions

    Directory of Open Access Journals (Sweden)

    Enrico Marelli

    2007-09-01

    Full Text Available The purpose of this paper was to analyze specialization and convergence of European countries and regions, within the framework of integration in the EU. This is important not only for long-term real convergence processes, but also for a proper functioning of the monetary union (in the line of research on the OCA's criteria, asymmetry of shocks and synchronization of business cycles. The position of new member states is particularly delicate, also considering the forthcoming adoption of the euro by some of them. As indicated by the EU Treaty, economic growth should be balanced with economic and social cohesion that includes a careful consideration of regional disparities. Our empirical investigation focuses on the regions of EU25, further broken up into other relevant groupings (EU15, EMU, and the new members' EU10 group, over the period from 1980 (or 1990 for EU10 to 2005. This paper considers a rather fine regional disaggregation (NUTS-2 level, counting 250 regions. The analysis of different indices of specialisation point to a prevalent increase of homogeneity of sector structures across European regions, although in some cases (especially in the industrial sector and in some services specialisation has increased. For convergence, a sigma convergence's analysis confirms a reduction of disparities, both at a country and regional level. However, a trade-off between fast national growth and internal distribution has emerged in the early stages of development, as in the case of new members. Moreover, beta convergence has also been established - regarding per capita income, employment and productivity - for almost all territorial aggregates (excluding the new members since 1999. The addition of structural variables, following a beta-conditional approach, indicates a positive role for services and a negative impact of agriculture. Finally, some preliminary results have been obtained by the innovative inclusion of specialisation indices within

  5. Recurrent polymorphic mating type variation in MadagascanBulbophyllumspecies (Orchidaceae) exemplifies a high incidence of auto-pollination in tropical orchids.

    Science.gov (United States)

    Gamisch, Alexander; Fischer, Gunter A; Comes, Hans Peter

    2014-06-01

    The transition from outcrossing to self-fertilization is one of the most common evolutionary changes in angiosperms. The orchid family exemplifies this evolutionary trend but, because of a general lack of large-scale surveys on auto-pollination in orchid taxa, the incidence and modes of auto-pollination among (sub)tropical orchids remain poorly known. In the present study, we assessed the frequency and mode of auto-pollination within and among species of a largely monophyletic group of Madagascan Bulbophyllum . The capacity for autonomous fruit set was investigated by bagging experiments in the greenhouse and the field, complemented with detailed floral micromorphological studies of the gynostemium. Our survey comprises 393 accessions, representing at least 78 species, and thus approximately 37% of the species diversity of the genus in the Madagascan region. Our studies revealed that mating type is directly related to gynostemium structure, most often involving the presence or absence of a physical barrier termed 'rostellum'. As a novel and unexpected finding, we identified eight species of a single lineage of Madagascan Bulbophyllum (termed 'clade C'), in which auto-pollinating morphs (selfers), either lacking a rostellum or (rarely) possessing a stigmatic rostellum, co-exist with their pollinator-dependent conspecifics (outcrossers). We hypothesize that auto-pollination via rostellum abortion has a simple genetic basis, and probably evolved rapidly and recurrently by subtle changes in the timing of rostellum development (heterochrony). Thus, species of clade C may have an intrinsic genetic and developmental lability toward auto-pollination, allowing rapid evolutionary response under environmental, perhaps human-disturbed conditions favouring reproductive assurance. Overall, these findings should stimulate further research on the incidence, evolution, and maintenance of mating type variation in tropical orchids, as well as how they adapt(ed) to changing

  6. Experience and convergence in spiritual direction.

    Science.gov (United States)

    Evans, Jean

    2015-02-01

    The practice of spiritual direction concerns the human experience of God. As praxis, spiritual direction has a long tradition in Western Christianity. It is a process rooted in spirituality with theology as its foundation. This paper explores the convergences between aspects of philosophy (contemplative awareness), psychology (Rogerian client-centered approach) and phenomenology. There are significant points of convergence between phenomenology and spiritual direction: first, in Ignatius of Loyola's phenomenological approach to his religious experience; second, in the appropriation by spiritual directors of concepts of epochē and empathy; third, in the process of "unpacking" religious experience within a spiritual direction interview.

  7. Service Creation and Deployment in Converged Networks

    DEFF Research Database (Denmark)

    Soler, José

    This monograph (Early Experiences related to Service Creation & Deployment in Converged Networks) presents different experiences related to architectures and mechanisms for deployment of telephony services, understood as especial features complementing the basic voice service. The context...... and Future Converged Networks”, carried out at the Technical University of Denmark in the period [April 2002-April 2005]. Even though the technologies presented in the text have evolved from that period until now, the presented scenarios and setups are still valid as interesting initial steps in the realm....

  8. Functional equivalence and evolutionary convergence in complex communities of microbial sponge symbionts.

    Science.gov (United States)

    Fan, Lu; Reynolds, David; Liu, Michael; Stark, Manuel; Kjelleberg, Staffan; Webster, Nicole S; Thomas, Torsten

    2012-07-03

    Microorganisms often form symbiotic relationships with eukaryotes, and the complexity of these relationships can range from those with one single dominant symbiont to associations with hundreds of symbiont species. Microbial symbionts occupying equivalent niches in different eukaryotic hosts may share functional aspects, and convergent genome evolution has been reported for simple symbiont systems in insects. However, for complex symbiont communities, it is largely unknown how prevalent functional equivalence is and whether equivalent functions are conducted by evolutionarily convergent mechanisms. Sponges represent an evolutionarily divergent group of species with common physiological and ecological traits. They also host complex communities of microbial symbionts and thus are the ideal model to test whether functional equivalence and evolutionary convergence exist in complex symbiont communities across phylogenetically divergent hosts. Here we use a sampling design to determine the phylogenetic and functional profiles of microbial communities associated with six sponge species. We identify common functions in the six microbiomes, demonstrating the existence of functional equivalence. These core functions are consistent with our current understanding of the biological and ecological roles of sponge-associated microorganisms and also provide insight into symbiont functions. Importantly, core functions also are provided in each sponge species by analogous enzymes and biosynthetic pathways. Moreover, the abundance of elements involved in horizontal gene transfer suggests their key roles in the genomic evolution of symbionts. Our data thus demonstrate evolutionary convergence in complex symbiont communities and reveal the details and mechanisms that underpin the process.

  9. Characterization of the cavitating flow in converging-diverging nozzle based on experimental investigations

    Directory of Open Access Journals (Sweden)

    Rudolf Pavel

    2014-03-01

    Full Text Available Cavitation phenomena occuring in converging-diverging nozzle (Venturi tube are described in the paper. A closed test circuit with possibility to control both flow rate and static pressure level were used. Loss coefficient was evaluated for different sigma numbers resulting in full „static“ characterization of the nozzle. Visualizations of the cavitation pattern development were acquired and matched with evolution of the loss coefficient. Three cavitation regimes are described: partial cavitation, fully developed cavitation, supercavitation.

  10. Functional equivalence and evolutionary convergence in complex communities of microbial sponge symbionts

    OpenAIRE

    Fan, Lu; Reynolds, David; Liu, Michael; Stark, Manuel; Kjelleberg, Staffan; Webster, Nicole S.; Thomas, Torsten

    2012-01-01

    Microorganisms often form symbiotic relationships with eukaryotes, and the complexity of these relationships can range from those with one single dominant symbiont to associations with hundreds of symbiont species. Microbial symbionts occupying equivalent niches in different eukaryotic hosts may share functional aspects, and convergent genome evolution has been reported for simple symbiont systems in insects. However, for complex symbiont communities, it is largely unknown how prevalent funct...

  11. International convergence of capital market interest rates.

    NARCIS (Netherlands)

    Fase, M.M.G.; Vlaar, P.J.G.

    1997-01-01

    This article investigates the extent of capital market interest rate convergence among six EU countries on the one hand, and a group of four countries with floating exchange rates - US, Germany, Japan and Switzerland - on the other. We conclude that interest rate changes within the EU have been and

  12. Fostering structural change? China's divergence and convergence ...

    African Journals Online (AJOL)

    The paper analyses the divergence and convergence of the characteristics of China's economic relationships with Africa – trade, investment and aid – with Africa's 'traditional' partners, i.e. Western industrialised countries. It argues that these relationships may foster structural transformation of African economies. The latter ...

  13. TRENDS IN THE CONVERGENCE OF WIRELESS NETWORKS

    Directory of Open Access Journals (Sweden)

    Daniel SORA

    2011-01-01

    Full Text Available In today’s technological market, there are many types of networks. These networks include wireless personal area networks (WPANs, wireless local area networks (WLANs, wireless metropolitan area networks (WMANs, and cellular networks. A vision of a future convergence of networks envisaged for WPANs, WLANs, WiMax, and cellular networks is presented in this paper.

  14. Culture and Social Psychology: Converging Perspectives

    Science.gov (United States)

    Dimaggio, Paul; Markus, Hazel Rose

    2010-01-01

    Views of culture in psychology and sociology have converged markedly in the past two decades. Both have rejected what Adams and Markus (2004) refer to as the "entity" conception of culture--the view that culture is coherent, stable, and located in the heads of collectivities' members--in favor of more supple and dynamic constructs. Culture, in…

  15. Convergence of coupled cluster perturbation theory

    Science.gov (United States)

    Eriksen, Janus J.; Kristensen, Kasper; Matthews, Devin A.; Jørgensen, Poul; Olsen, Jeppe

    2016-12-01

    The convergence of a recently proposed coupled cluster (CC) family of perturbation series [J. J. Eriksen et al., J. Chem. Phys. 140, 064108 (2014)], in which the energetic difference between two CC models—a low-level parent and a high-level target model—is expanded in orders of the Møller-Plesset (MP) fluctuation potential, is investigated for four prototypical closed-shell systems (Ne, singlet CH2, distorted HF, and F-) in standard and augmented basis sets. In these investigations, energy corrections of the various series have been calculated to high orders and their convergence radii have been determined by probing for possible front- and back-door intruder states, the existence of which would make the series divergent. In summary, we conclude how it is primarily the choice of the target state, and not the choice of the parent state, which ultimately governs the convergence behavior of a given series. For example, restricting the target state to, say, triple or quadruple excitations might remove intruders present in series which target the full configuration interaction limit, such as the standard MP series. Furthermore, we find that whereas a CC perturbation series might converge within standard correlation consistent basis sets, it may start to diverge whenever these become augmented by diffuse functions, similar to the MP case. However, unlike for the MP case, such potential divergences are not found to invalidate the practical use of the low-order corrections of the CC perturbation series.

  16. Looking for convergence: Stakeholders' perceptions of cocoa ...

    African Journals Online (AJOL)

    This study was undertaken with the objective of evaluating the extent of convergence on the part of key stakeholders in the cocoa sector on the problems of cocoa extension and how to address it. The study was carried out in the Atwima Mponua and Amansie West districts of the Ashanti region in 2008 although some of the ...

  17. Intermediates and Generic Convergence to Equilibria

    DEFF Research Database (Denmark)

    Marcondes de Freitas, Michael; Wiuf, Carsten; Feliu, Elisenda

    2017-01-01

    Known graphical conditions for the generic and global convergence to equilibria of the dynamical system arising from a reaction network are shown to be invariant under the so-called successive removal of intermediates, a systematic procedure to simplify the network, making the graphical condition...

  18. Block Coordinate Descent Only Converge to Minimizers

    OpenAIRE

    Song, Enbin; Shen, Zhubin; Shi, Qingjiang

    2017-01-01

    Given a non-convex twice continuously differentiable cost function with Lipschitz continuous gradient, we prove that all of block coordinate gradient descent, block mirror descent and proximal block coordinate descent converge to a local minimizer, almost surely with random initialization. Furthermore, we show that these results also hold true even for the cost functions with non-isolated critical points.

  19. Converging technologies: shaping the future of medicine

    Directory of Open Access Journals (Sweden)

    Iraj nabipour

    2015-01-01

    Full Text Available The miniaturization and virtualization processes drive converging technologies from interactions between the NBIC (Nano, Bio, Info, and Cogno technologies. The converging technologies stimulate innovation, promote research and development in different fields and produce revolutionary progresses in medicine. These technologies enable us to create contacts between brains and machines, the growth in molecular nanotechnology, the construction of respirocytes, chromallocytes, clottocytes, nanorobotic phagocytes, and nanobots. Nanobots would enter the nucleus of a cell and extract all of the genetic material and replace it with a synthetically produced copy of the original that has been manufactured in a laboratory to contain only non-defective base-pairs. It is predicted that “the regenerative medicine”, as a megatrend, will have an enormous effect on medical technologies and clinical sciences. Regenerative medicine is an application field of converging technologies in translational medicine. It attempts to translate the results of tissue engineering to construct 3D tissues and organs. Regenerative medicine is also an exciting field for induced pluripotent stem cell (iPSC and promises to bring about a paradigm shift to health care. Accumulating evidence indicates that converging technologies will offer great potentials for regenerative medicine to create innovative treatments for diseases that the traditional therapies have not been effective yet.

  20. The Convergence Coefficient across Political Systems

    Science.gov (United States)

    Schofield, Norman

    2013-01-01

    Formal work on the electoral model often suggests that parties or candidates should locate themselves at the electoral mean. Recent research has found no evidence of such convergence. In order to explain nonconvergence, the stochastic electoral model is extended by including estimates of electoral valence. We introduce the notion of a convergence coefficient, c. It has been shown that high values of c imply that there is a significant centrifugal tendency acting on parties. We used electoral surveys to construct a stochastic valence model of the the elections in various countries. We find that the convergence coefficient varies across elections in a country, across countries with similar regimes, and across political regimes. In some countries, the centripetal tendency leads parties to converge to the electoral mean. In others the centrifugal tendency dominates and some parties locate far from the electoral mean. In particular, for countries with proportional electoral systems, namely, Israel, Turkey, and Poland, the centrifugal tendency is very high. In the majoritarian polities of the United States and Great Britain, the centrifugal tendency is very low. In anocracies, the autocrat imposes limitations on how far from the origin the opposition parties can move. PMID:24385886

  1. Mnemonic convergence in the human hippocampus

    NARCIS (Netherlands)

    Backus, A.R.; Bosch, S.E.; Ekman, M.; Vicente-Grabovetsky, A.; Doeller, C.F.

    2016-01-01

    The ability to form associations between a multitude of events is the hallmark of episodic memory. Computational models have espoused the importance of the hippocampus as convergence zone, binding different aspects of an episode into a coherent representation, by integrating information from

  2. Mediamorphosis: Analyzing the Convergence of Digital Media ...

    African Journals Online (AJOL)

    User

    2011-04-19

    Apr 19, 2011 ... Will the emergence and development of digital media forms mean the death of the traditional media forms? ... Key Words: Mediamorphosis, Convergence, Digital Media, African. Traditional Media, Media ... has led to their wide diffusion and application, thus increasing their economic and social impact.

  3. The convergence coefficient across political systems.

    Science.gov (United States)

    Gallego, Maria; Schofield, Norman

    2013-01-01

    Formal work on the electoral model often suggests that parties or candidates should locate themselves at the electoral mean. Recent research has found no evidence of such convergence. In order to explain nonconvergence, the stochastic electoral model is extended by including estimates of electoral valence. We introduce the notion of a convergence coefficient, c. It has been shown that high values of c imply that there is a significant centrifugal tendency acting on parties. We used electoral surveys to construct a stochastic valence model of the the elections in various countries. We find that the convergence coefficient varies across elections in a country, across countries with similar regimes, and across political regimes. In some countries, the centripetal tendency leads parties to converge to the electoral mean. In others the centrifugal tendency dominates and some parties locate far from the electoral mean. In particular, for countries with proportional electoral systems, namely, Israel, Turkey, and Poland, the centrifugal tendency is very high. In the majoritarian polities of the United States and Great Britain, the centrifugal tendency is very low. In anocracies, the autocrat imposes limitations on how far from the origin the opposition parties can move.

  4. Radio, Convergence and Development in Africa | IDRC ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Radio remains the dominant mass medium in Africa, and indeed across much of the developing world. Moreover, radio is increasing its reach and interactivity as a result of changes in the regulatory environment, the growth of citizen journalism and convergence between radio and other information and communication ...

  5. Collaborative Instructional Strategies to Enhance Knowledge Convergence

    Science.gov (United States)

    Draper, Darryl C.

    2015-01-01

    To promote knowledge convergence through collaborative learning activities in groups, this qualitative case study involved a layered approach for the design and delivery of a highly collaborative learning environment incorporating various instructional technologies grounded in learning theory. In a graduate-level instructional technology course,…

  6. Professional Communication and Translation in Convergence

    DEFF Research Database (Denmark)

    Gnecci, Marusca; Maylath, Bruce; Mousten, Birthe

    2008-01-01

    As translation of technical documents becomes commonplace, and as translation becomes more automated, the roles of translator and technical communicator appear to be converging. This paper examines the trend revealed from recent surveys, and it suggests further research to determine if the trend ...... is likely to continue. The  paper also provides recommendations for academic programs interested in adjusting to the trend....

  7. ERROR CONVERGENCE ANALYSIS FOR LOCAL HYPERTHERMIA APPLICATIONS

    Directory of Open Access Journals (Sweden)

    NEERU MALHOTRA

    2016-01-01

    Full Text Available The accuracy of numerical solution for electromagnetic problem is greatly influenced by the convergence of the solution obtained. In order to quantify the correctness of the numerical solution the errors produced on solving the partial differential equations are required to be analyzed. Mesh quality is another parameter that affects convergence. The various quality metrics are dependent on the type of solver used for numerical simulation. The paper focuses on comparing the performance of iterative solvers used in COMSOL Multiphysics software. The modeling of coaxial coupled waveguide applicator operating at 485MHz has been done for local hyperthermia applications using adaptive finite element method. 3D heat distribution within the muscle phantom depicting spherical leison and localized heating pattern confirms the proper selection of the solver. The convergence plots are obtained during simulation of the problem using GMRES (generalized minimal residual and geometric multigrid linear iterative solvers. The best error convergence is achieved by using nonlinearity multigrid solver and further introducing adaptivity in nonlinear solver.

  8. Governance Challenges of Technological Systems Convergence

    Science.gov (United States)

    Whitman, Jim

    2006-01-01

    The convergence of several technological systems (especially nanotechnology, biotechnology, information technology, and robotics) has now been adopted as a strategic goal by several countries, most notably the United States and those of the European Union. The anticipated benefits and related fears of competitive disadvantage have brought together…

  9. Strong ideal convergence in probabilistic metric spaces

    Indian Academy of Sciences (India)

    In the present paper we introduce the concepts of strongly ideal convergent sequence and strong ideal Cauchy sequence in a probabilistic metric (PM) space endowed with the strong topology, and establish some basic facts. Next, we define the strong ideal limit points and the strong ideal cluster points of a sequence in this ...

  10. Asymmetric filter convergence and completeness | Frith ...

    African Journals Online (AJOL)

    Completeness for metric spaces is traditionally presented in terms of convergence of Cauchy sequences, and for uniform spaces in terms of Cauchy filters. Somewhat more abstractly, a uniform space is complete if and only if it is closed in every uniform space in which it is embedded, and so isomorphic to any space in ...

  11. Strong ideal convergence in probabilistic metric spaces

    Indian Academy of Sciences (India)

    Abstract. In the present paper we introduce the concepts of strongly ideal convergent sequence and strong ideal Cauchy sequence in a probabilistic metric (PM) space endowed with the strong topology, and establish some basic facts. Next, we define the strong ideal limit points and the strong ideal cluster points of a ...

  12. Another Perspective: A Response to "Toward Convergence"

    Science.gov (United States)

    Regelski, Thomas A.

    2013-01-01

    This response by Thomas A. Regelski was solicited to complement the lead article in this issue, "Toward Convergence: Adapting Music Education to Contemporary Society and Participatory Culture" by Evan S. Tobias. The author notes that many interesting and vital questions and alternatives that are often studiously ignored, overlooked, or taken for…

  13. Evolutionary convergence and biologically embodied cognition

    NARCIS (Netherlands)

    Keijzer, Franciscus

    2017-01-01

    The study of evolutionary patterns of cognitive convergence would be greatly helped by a clear demarcation of cognition. Cognition is often used as an equivalent of mind, making it difficult to pin down empirically or to apply it confidently beyond the human condition. Recent developments in

  14. Mixed Emotion and Its Functional and Semantic Potential (Exemplified with the Word Dislike

    Directory of Open Access Journals (Sweden)

    Алексей Андреевич Штеба

    2015-12-01

    Full Text Available The article touches upon the problem of language categorization of mixed emotions from the perspective of functional and semantic aspects. Using the word dislike as an example the author shows how the reflection process of polyvalency in any emotional experience is revealed in the language: from implicit emotive ambivalence to its explicitness. It is postulated that the seme “mixture” is inherent to any word that has “emotion” and “valency” semes as their semantic components. The above-mentioned thesis is revealed from the combined and separate spelling of the Russian particle “НЕ” with verbs and nouns that are used to describe the process of mixed emotion categorization. It is also proved that pragmatic potential of expressing mixed emotions in emotional situations includes the speaker’s target at his\\her interlocutor, anticipation of emotional reaction, and maintenance of a constructive communication tonality. The article demonstrates that categorization of mixed emotions presents a new stage in verbal emotion objectification and is the evolution marker of human emotional intelligence.

  15. Multidimensional Convergence in Future 5G Networks

    Science.gov (United States)

    Ruffini, Marco

    2017-02-01

    Future 5G services are characterised by unprecedented need for high rate, ubiquitous availability, ultra-low latency and high reliability. The fragmented network view that is widespread in current networks will not stand the challenge posed by next generations of users. A new vision is required, and this paper provides an insight on how network convergence and application-centric approaches will play a leading role towards enabling the 5G vision. The paper, after expressing the view on the need for an end-to-end approach to network design, brings the reader into a journey on the expected 5G network requirements and outlines some of the work currently carried out by main standardisation bodies. It then proposes the use of the concept of network convergence for providing the overall architectural framework to bring together all the different technologies within a unifying and coherent network ecosystem. The novel interpretation of multi-dimensional convergence we introduce leads us to the exploration of aspects of node consolidation and converged network architectures, delving into details of optical-wireless integration and future convergence of optical data centre and access-metro networks. We then discuss how ownership models enabling network sharing will be instrumental in realising the 5G vision. The paper concludes with final remarks on the role SDN will play in 5G and on the need for new business models that reflect the application-centric view of the network. Finally, we provide some insight on growing research areas in 5G networking.

  16. Cultural transmission results in convergence towards colour term universals

    Science.gov (United States)

    Xu, Jing; Dowman, Mike; Griffiths, Thomas L.

    2013-01-01

    As in biological evolution, multiple forces are involved in cultural evolution. One force is analogous to selection, and acts on differences in the fitness of aspects of culture by influencing who people choose to learn from. Another force is analogous to mutation, and influences how culture changes over time owing to errors in learning and the effects of cognitive biases. Which of these forces need to be appealed to in explaining any particular aspect of human cultures is an open question. We present a study that explores this question empirically, examining the role that the cognitive biases that influence cultural transmission might play in universals of colour naming. In a large-scale laboratory experiment, participants were shown labelled examples from novel artificial systems of colour terms and were asked to classify other colours on the basis of those examples. The responses of each participant were used to generate the examples seen by subsequent participants. By simulating cultural transmission in the laboratory, we were able to isolate a single evolutionary force—the effects of cognitive biases, analogous to mutation—and examine its consequences. Our results show that this process produces convergence towards systems of colour terms similar to those seen across human languages, providing support for the conclusion that the effects of cognitive biases, brought out through cultural transmission, can account for universals in colour naming. PMID:23486436

  17. Cultural transmission results in convergence towards colour term universals.

    Science.gov (United States)

    Xu, Jing; Dowman, Mike; Griffiths, Thomas L

    2013-05-07

    As in biological evolution, multiple forces are involved in cultural evolution. One force is analogous to selection, and acts on differences in the fitness of aspects of culture by influencing who people choose to learn from. Another force is analogous to mutation, and influences how culture changes over time owing to errors in learning and the effects of cognitive biases. Which of these forces need to be appealed to in explaining any particular aspect of human cultures is an open question. We present a study that explores this question empirically, examining the role that the cognitive biases that influence cultural transmission might play in universals of colour naming. In a large-scale laboratory experiment, participants were shown labelled examples from novel artificial systems of colour terms and were asked to classify other colours on the basis of those examples. The responses of each participant were used to generate the examples seen by subsequent participants. By simulating cultural transmission in the laboratory, we were able to isolate a single evolutionary force-the effects of cognitive biases, analogous to mutation-and examine its consequences. Our results show that this process produces convergence towards systems of colour terms similar to those seen across human languages, providing support for the conclusion that the effects of cognitive biases, brought out through cultural transmission, can account for universals in colour naming.

  18. Morphodynamic modeling of a large inside sand bar and its dextral morphology in a convergent estuary: Qiantang Estuary, China

    NARCIS (Netherlands)

    Xie, Dongfeng; Gao, Shu; Wang, Zhengbing; Pan, Cunhong; Wu, Xiuguang; Wang, Qiushun

    2017-01-01

    We investigate the evolution of a large-scale sand body, a unique type of sandbars in a convergent estuary. Specifically, we analyze and simulate the sand deposition system (defined as an inside bar) in the Qiantang Estuary (QE) in China. The deposit is 130 km long and up to 10 m thick, and is

  19. A green-cotyledon/stay-green mutant exemplifies the ancient whole-genome duplications in soybean.

    Science.gov (United States)

    Nakano, Michiharu; Yamada, Tetsuya; Masuda, Yu; Sato, Yutaka; Kobayashi, Hideki; Ueda, Hiroaki; Morita, Ryouhei; Nishimura, Minoru; Kitamura, Keisuke; Kusaba, Makoto

    2014-10-01

    The recent whole-genome sequencing of soybean (Glycine max) revealed that soybean experienced whole-genome duplications 59 million and 13 million years ago, and it has an octoploid-like genome in spite of its diploid nature. We analyzed a natural green-cotyledon mutant line, Tenshin-daiseitou. The physiological analysis revealed that Tenshin-daiseitou shows a non-functional stay-green phenotype in senescent leaves, which is similar to that of the mutant of Mendel's green-cotyledon gene I, the ortholog of SGR in pea. The identification of gene mutations and genetic segregation analysis suggested that defects in GmSGR1 and GmSGR2 were responsible for the green-cotyledon/stay-green phenotype of Tenshin-daiseitou, which was confirmed by RNA interference (RNAi) transgenic soybean experiments using GmSGR genes. The characterized green-cotyledon double mutant d1d2 was found to have the same mutations, suggesting that GmSGR1 and GmSGR2 are D1 and D2. Among the examined d1d2 strains, the d1d2 strain K144a showed a lower Chl a/b ratio in mature seeds than other strains but not in senescent leaves, suggesting a seed-specific genetic factor of the Chl composition in K144a. Analysis of the soybean genome sequence revealed four genomic regions with microsynteny to the Arabidopsis SGR1 region, which included the GmSGR1 and GmSGR2 regions. The other two regions contained GmSGR3a/GmSGR3b and GmSGR4, respectively, which might be pseudogenes or genes with a function that is unrelated to Chl degradation during seed maturation and leaf senescence. These GmSGR genes were thought to be produced by the two whole-genome duplications, and they provide a good example of such whole-genome duplication events in the evolution of the soybean genome. © The Author 2014. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  20. Convergence characteristics of the multiple input, multiple output LMS algorithm

    Science.gov (United States)

    Snyder, Scott D.; Hansen, Colin H.; Clark, Robert L.

    1992-01-01

    The convergence characteristics of the multiple input, multiple output LMS algorithm, as applied to active noise and vibration control systems, are examined. The mean square error during the convergence process, as well as the final converged value, are examined analytically and in computer simulation. It is shown that the ratio of number of error sensors to number of control sources has a significant influence upon both the converging and converged value of the mean square error. Other active control system variables, such as the inherent time delays and structural/acoustic transfer functions, are also shown to have a significant influence upon the convergence process.

  1. Convergence of Newton's method for a single real equation

    Science.gov (United States)

    Campbell, C. W.

    1985-01-01

    Newton's method for finding the zeroes of a single real function is investigated in some detail. Convergence is generally checked using the Contraction Mapping Theorem which yields sufficient but not necessary conditions for convergence of the general single point iteration method. The resulting convergence intervals are frequently considerably smaller than actual convergence zones. For a specific single point iteration method, such as Newton's method, better estimates of regions of convergence should be possible. A technique is described which, under certain conditions (frequently satisfied by well behaved functions) gives much larger zones where convergence is guaranteed.

  2. On domains of convergence in optimization problems

    Science.gov (United States)

    Diaz, Alejandro R.; Shaw, Steven S.; Pan, Jian

    1990-01-01

    Numerical optimization algorithms require the knowledge of an initial set of design variables. Starting from an initial design x(sup 0), improved solutions are obtained by updating the design iteratively in a way prescribed by the particular algorithm used. If the algorithm is successful, convergence is achieved to a local optimal solution. Let A denote the iterative procedure that characterizes a typical optimization algorithm, applied to the problem: Find x belonging to R(sup n) that maximizes f(x) subject to x belonging to Omega contained in R(sup n). We are interested in problems with several local maxima (x(sub j))(sup *), j=1, ..., m, in the feasible design space Omega. In general, convergence of the algorithm A to a specific solution (x(sub j))(sup *) is determined by the choice of initial design x(sup 0). The domain of convergence D(sub j) of A associated with a local maximum (x(sub j))(sup *) is a subset of initial designs x(sup 0) in Omega such that the sequence (x(sup k)), k=0,1,2,... defined by x(sup k+1) = A(x(sup k)), k=0,1,... converges to (x(sub j))(sup *). The set D(sub j) is also called the basin of attraction of (x(sub j))(sup *). Cayley first proposed the problem of finding the basin of attraction for Newton's method in 1897. It has been shown that the basin of attraction for Newton's method exhibits chaotic behavior in problems with polynomial objective. This implies that there may be regions in the feasible design space where arbitrarily close starting points will converge to different local optimal solutions. Furthermore, the boundaries of the domains of convergence may have a very complex, even fractal structure. In this paper we show that even simple structural optimization problems solved using standard gradient based (first order) algorithms exhibit similar features.

  3. [Ambivalence--a key concept in gerontology? Elements of heuristics exemplified by identity formation in old age].

    Science.gov (United States)

    Lüscher, Kurt; Haller, Miriam

    2016-01-01

    Ambivalence is a widely used concept in gerontology, mostly used in the common sense meaning. We propose that an elaborated notion based on the historical and systematic analysis, reveals important theoretical, methodological and practical potentials of the idea of ambivalence for the study of aging. We exemplify this view by proposing a heuristic perspective for the analysis of processes to constitute and reconstitute identities in old age using a model based on a multidimensional understanding of ambivalence. Ambivalence is defined as referring to the experiences of vacillating between polar contradictions of feeling, thinking, wanting and social structures in the search for the sense and meaning of social relationships, facts and texts, which are important for unfolding and altering facets of the self and agency.

  4. Evolution of factors affecting placental oxygen transfer

    DEFF Research Database (Denmark)

    Carter, A M

    2009-01-01

    states, are more amenable to analysis. This is exemplified by factors contributing, respectively, to blood oxygen affinity and placental diffusing capacity. Comparative genomics has given fresh insight into the evolution of the beta-globin gene complex. In higher primates, duplication of an embryonic...... that epitheliochorial placentation is a derived state and that the common ancestor of placental mammals probably had a placenta of the endotheliochorial type. Where evolutionary trends are implied for mammals as a whole or within orders such as primates they often accompany a switch in reproductive strategy...

  5. Non-surgical interventions for convergence insufficiency.

    Science.gov (United States)

    Scheiman, Mitchell; Gwiazda, Jane; Li, Tianjing

    2011-03-16

    Convergence insufficiency is a common eye muscle co-ordination problem in which the eyes have a strong tendency to drift outward (exophoria) when reading or doing close work. Symptoms may include eye strain, headaches, double vision, print moving on the page, frequent loss of place when reading, inability to concentrate, and short attention span. To systematically assess and synthesize evidence from randomized controlled trials (RCTs) on the effectiveness of non-surgical interventions for convergence insufficiency. We searched The Cochrane Library, MEDLINE, EMBASE, Science Citation Index, the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com) and ClinicalTrials.gov (www.clinicaltrials.gov ) on 7 October 2010. We manually searched reference lists and optometric journals. We included RCTs examining any form of non-surgical intervention against placebo, no treatment, sham treatment, or each other. Two authors independently assessed eligibility, risk of bias, and extracted data. We performed meta-analyses when appropriate. We included six trials (three in children, three in adults) with a total of 475 participants. We graded four trials at low risk of bias.Evidence from one trial (graded at low risk of bias) suggests that base-in prism reading glasses was no more effective than placebo reading glasses in improving clinical signs or symptoms in children.Evidence from one trial (graded at high risk of bias) suggests that base-in prism glasses using a progressive addition lens design was more effective than progressive addition lens alone in decreasing symptoms in adults. At three weeks of therapy, the mean difference in Convergence Insufficiency Symptoms Survey (CISS) score was -10.24 points (95% confidence interval (CI) -15.45 to -5.03).Evidence from two trials (graded at low risk of bias) suggests that outpatient (or office-based as used in the US) vision therapy/orthoptics was more effective than home-based convergence exercises (or pencil push

  6. Computed tomography findings in convergent strabismus fixus

    Energy Technology Data Exchange (ETDEWEB)

    Ohta, Michitaka; Iwashige, Hiroyasu; Hayashi, Takao; Maruo, Toshio [Teikyo Univ., Tokyo (Japan). Faculty of Medicine

    1995-08-01

    X-ray computed tomography (CT) of the eyeball and orbit revealed the cause of eye movement disorder in convergent strabismus fixus. The findings suggest that the disease can be diagnosed and treated at an early stage. Twelve cases of progressive esotropia with high myopia and 20 cases with normal visual acuity served as subjects in this study. The CT slice was parallel to the German horizontal plane, and the lens and medial and lateral rectus muscles were scanned. The average axial length of the affected eyes was significantly longer than in normal eyes. In progressive esotropia, the characteristic CT findings are an elongated eyeball, mechanical contact between the eyeball and lateral wall of the orbit, and a downward displacement of the lateral rectus muscle. Thus, it is reasonable to conclude that eye movement disorder in convergent strabismus fixus results from weakness of the lateral rectus muscle which has been displaced downward due to compression of the eyeball against the orbital wall. (author).

  7. Flow over convergent and divergent wall riblets

    Energy Technology Data Exchange (ETDEWEB)

    Koeltzsch, K.; Dinkelacker, A.; Grundmann, R. [Institut fuer Luft- und Raumfahrttechnik, Technische Universitaet Dresden, 36460 Merkers (Germany)

    2002-08-01

    Fast swimming sharks have small riblets on their skin, which are assumed to improve the swimming performance of the fish. Fluid dynamic experiments in water as well as in air confirm this assumption. With riblet surfaces as compared to smooth surfaces, drag reductions up to about 10% were measured. The overall riblet pattern on sharks shows parallel riblets directed from head to tail, but besides this overall pattern fast swimming sharks have also small areas with converging riblets and others with diverging riblets. In the present study the velocity field over convergent and divergent riblet patterns is investigated by hot-wire measurements in turbulent pipe flow. Significant changes in the near wall velocity field were found. (orig.)

  8. Rousseau and Marx: Convergence or divergence?

    Directory of Open Access Journals (Sweden)

    Lošonc Alpar

    2012-01-01

    Full Text Available Rousseau and Marx represent two paradigmatic variants of a radical opposition to the world. Without a doubt, there are significant moments of convergence between these thinkers, for instance in terms of division of labour, or in respect to the self-commandment. However, it is our contention that despite certain currents in literature, the tendencies of divergence are stronger than convergence, therefore, we argue that these thinkers signify two different variants of radical thought. We base these differences in a reading of Rousseau that focuses on collective authenticity, justice, self-presentation of people and protest against envy. Marx cannot be read from the perspective of the intensified crisis of non-authenticity, in fact, his critique of political economy generates a reflexive field (overcoming of the wage labour, etc., which is deeply divergent compared to Rousseau.

  9. RNA polymerase II collision interrupts convergent transcription

    DEFF Research Database (Denmark)

    Hobson, David J; Wei, Wu; Steinmetz, Lars M

    2012-01-01

    Antisense noncoding transcripts, genes-within-genes, and convergent gene pairs are prevalent among eukaryotes. The existence of such transcription units raises the question of what happens when RNA polymerase II (RNAPII) molecules collide head-to-head. Here we use a combination of biochemical...... and genetic approaches in yeast to show that polymerases transcribing opposite DNA strands cannot bypass each other. RNAPII stops but does not dissociate upon head-to-head collision in vitro, suggesting that opposing polymerases represent insurmountable obstacles for each other. Head-to-head collision in vivo...... also results in RNAPII stopping, and removal of collided RNAPII from the DNA template can be achieved via ubiquitylation-directed proteolysis. Indeed, in cells lacking efficient RNAPII polyubiquitylation, the half-life of collided polymerases increases, so that they can be detected between convergent...

  10. Non-surgical interventions for convergence insufficiency

    Science.gov (United States)

    Scheiman, Mitchell; Gwiazda, Jane; Li, Tianjing

    2014-01-01

    Background Convergence insufficiency is a common eye muscle co-ordination problem in which the eyes have a strong tendency to drift outward (exophoria) when reading or doing close work. Symptoms may include eye strain, headaches, double vision, print moving on the page, frequent loss of place when reading, inability to concentrate, and short attention span. Objectives To systematically assess and synthesize evidence from randomized controlled trials (RCTs) on the effectiveness of non-surgical interventions for convergence insufficiency. Search strategy We searched The Cochrane Library, MEDLINE, EMBASE, Science Citation Index, the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com) and ClinicalTrials.gov (www.clinicaltrials.gov) on 7 October 2010. We manually searched reference lists and optometric journals. Selection criteria We included RCTs examining any form of non-surgical intervention against placebo, no treatment, sham treatment, or each other. Data collection and analysis Two authors independently assessed eligibility, risk of bias, and extracted data. We performed meta-analyses when appropriate. Main results We included six trials (three in children, three in adults) with a total of 475 participants. We graded four trials at low risk of bias. Evidence from one trial (graded at low risk of bias) suggests that base-in prism reading glasses was no more effective than placebo reading glasses in improving clinical signs or symptoms in children. Evidence from one trial (graded at high risk of bias) suggests that base-in prism glasses using a progressive addition lens design was more effective than progressive addition lens alone in decreasing symptoms in adults. At three weeks of therapy, the mean difference in Convergence Insufficiency Symptoms Survey (CISS) score was −10.24 points (95% confidence interval (CI) −15.45 to −5.03). Evidence from two trials (graded at low risk of bias) suggests that outpatient (or office-based as used in the

  11. Generalized functions, convergence structures, and their applications

    CERN Document Server

    Pap, Endre; Pilipović, Stevan; Vladimirov, Vasilij; International Conference "Generalized functions, convergence structures and their applications" (GFCA-87)

    1988-01-01

    This Proceedings consists of a collection of papers presented at the International Conference "Generalized functions, convergence structures and their applications" held from June 23-27, 1987 in Dubrovnik, Yugoslavia (GFCA-87): 71 participants from 21 countr~es from allover the world took part in the Conference. Proceedings reflects the work of the Conference. Plenary lectures of J. Burzyk, J. F. Colombeau, W. Gahler, H. Keiter, H. Komatsu, B. Stankovic, H. G. Tillman, V. S. Vladimirov provide an up-to-date account of the cur­ rent state of the subject. All these lectures, except H. G. Tillman's, are published in this volume. The published communications give the contemporary problems and achievements in the theory of generalized functions, in the theory of convergence structures and in their applications, specially in the theory of partial differential equations and in the mathematical physics. New approaches to the theory of generalized functions are presented, moti­ vated by concrete problems of applicat...

  12. A Numerical, Literal, and Converged Perturbation Algorithm

    Science.gov (United States)

    Wiesel, William E.

    2017-09-01

    The KAM theorem and von Ziepel's method are applied to a perturbed harmonic oscillator, and it is noted that the KAM methodology does not allow for necessary frequency or angle corrections, while von Ziepel does. The KAM methodology can be carried out with purely numerical methods, since its generating function does not contain momentum dependence. The KAM iteration is extended to allow for frequency and angle changes, and in the process apparently can be successfully applied to degenerate systems normally ruled out by the classical KAM theorem. Convergence is observed to be geometric, not exponential, but it does proceed smoothly to machine precision. The algorithm produces a converged perturbation solution by numerical methods, while still retaining literal variable dependence, at least in the vicinity of a given trajectory.

  13. Entropy and Gravity Concepts as New Methodological Indexes to Investigate Technological Convergence: Patent Network-Based Approach

    Science.gov (United States)

    Cho, Yongrae; Kim, Minsung

    2014-01-01

    The volatility and uncertainty in the process of technological developments are growing faster than ever due to rapid technological innovations. Such phenomena result in integration among disparate technology fields. At this point, it is a critical research issue to understand the different roles and the propensity of each element technology for technological convergence. In particular, the network-based approach provides a holistic view in terms of technological linkage structures. Furthermore, the development of new indicators based on network visualization can reveal the dynamic patterns among disparate technologies in the process of technological convergence and provide insights for future technological developments. This research attempts to analyze and discover the patterns of the international patent classification codes of the United States Patent and Trademark Office's patent data in printed electronics, which is a representative technology in the technological convergence process. To this end, we apply the physical idea as a new methodological approach to interpret technological convergence. More specifically, the concepts of entropy and gravity are applied to measure the activities among patent citations and the binding forces among heterogeneous technologies during technological convergence. By applying the entropy and gravity indexes, we could distinguish the characteristic role of each technology in printed electronics. At the technological convergence stage, each technology exhibits idiosyncratic dynamics which tend to decrease technological differences and heterogeneity. Furthermore, through nonlinear regression analysis, we have found the decreasing patterns of disparity over a given total period in the evolution of technological convergence. This research has discovered the specific role of each element technology field and has consequently identified the co-evolutionary patterns of technological convergence. These new findings on the evolutionary

  14. COMPARATIVE FINANCIAL STATEMENTS. CONVERGENCE VERSUS DIVERGENCE

    Directory of Open Access Journals (Sweden)

    Nicolae ECOBICI

    2010-09-01

    Full Text Available In this paper I compared the Romanian financial statements with the US GAAP financial statements in terms of two criteria: first the reference period and secondly the shape, structure and content of financial statements. Nowadays the two accounting systems, the French and Anglo-Saxon, tend to harmonize. I will present the convergences and the divergences between the financial statements of Romania, subject to OMFP 3055/2009, in parallel with the Anglo-Saxon accounting system.

  15. Design calculations for NIF convergent ablator experiments

    Directory of Open Access Journals (Sweden)

    Olson R.E.

    2013-11-01

    Full Text Available The NIF convergent ablation tuning effort is underway. In the early experiments, we have discovered that the design code simulations over-predict the capsule implosion velocity and shock flash ρr, but under-predict the hohlraum x-ray flux measurements. The apparent inconsistency between the x-ray flux and radiography data implies that there are important unexplained aspects of the hohlraum and/or capsule behavior.

  16. Arieti and Bowlby: convergence and direct influence.

    Science.gov (United States)

    Bacciagaluppi, Marco

    2015-09-01

    Arieti was a great specialist of schizophrenia and Bowlby was the initiator of attachment theory. Working independently on the two sides of the Atlantic, they converged on a range of topics, such as evolutionary theory, mourning, trauma, violence, and therapy as art and science. Later, Bowlby exerted a direct influence on Arieti, which Arieti acknowledged in his Love Can Be Found. Finally, the two authors cooperated in the second edition of the American Handbook of Psychiatry.

  17. Innovation diffusion, technological convergence and economic growth

    OpenAIRE

    Andergassen, Rainer; Nardini, Franco; Ricottilli, Massimo

    2013-01-01

    The paper investigates the mechanics through which novel technological principles are developed and diffused throughout an economy consisting of a technologically heterogeneous ensemble of firms. In the model entrepreneurs invest in the discovery and in the diffusion of a technological principle and their profit flow depends on how many firms adopt the innovation and on how long it takes other entrepreneurs to improve it. We show that technological convergence emerges from the competition amo...

  18. Design Calculations For NIF Convergent Ablator Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Olson, R E; Hicks, D G; Meezan, N B; Callahan, D A; Landen, O L; Jones, O S; Langer, S H; Kline, J L; Wilson, D C; Rinderknecht, H; Zylstra, A; Petrasso, R D

    2011-10-25

    The NIF convergent ablation tuning effort is underway. In the early experiments, we have discovered that the design code simulations over-predict the capsule implosion velocity and shock flash rhor, but under-predict the hohlraum x-ray flux measurements. The apparent inconsistency between the x-ray flux and radiography data implies that there are important unexplained aspects of the hohlraum and/or capsule behavior.

  19. Human Capital Convergence: Evidence from the Punjab

    OpenAIRE

    Uzma Afzal

    2012-01-01

    While the literature on economic growth provides mixed evidence on convergence across different countries and regions, a large number of studies point toward the widening income gap between rich and poor. In the development literature, a broader range of national welfare indicators beyond income per capita—health and education in particular—are considered important instruments for measuring progress in human development. This article examines education and other selective welfare indicators t...

  20. Parallel sites implicate functional convergence of the hearing gene prestin among echolocating mammals.

    Science.gov (United States)

    Liu, Zhen; Qi, Fei-Yan; Zhou, Xin; Ren, Hai-Qing; Shi, Peng

    2014-09-01

    Echolocation is a sensory system whereby certain mammals navigate and forage using sound waves, usually in environments where visibility is limited. Curiously, echolocation has evolved independently in bats and whales, which occupy entirely different environments. Based on this phenotypic convergence, recent studies identified several echolocation-related genes with parallel sites at the protein sequence level among different echolocating mammals, and among these, prestin seems the most promising. Although previous studies analyzed the evolutionary mechanism of prestin, the functional roles of the parallel sites in the evolution of mammalian echolocation are not clear. By functional assays, we show that a key parameter of prestin function, 1/α, is increased in all echolocating mammals and that the N7T parallel substitution accounted for this functional convergence. Moreover, another parameter, V1/2, was shifted toward the depolarization direction in a toothed whale, the bottlenose dolphin (Tursiops truncatus) and a constant-frequency (CF) bat, the Stoliczka's trident bat (Aselliscus stoliczkanus). The parallel site of I384T between toothed whales and CF bats was responsible for this functional convergence. Furthermore, the two parameters (1/α and V1/2) were correlated with mammalian high-frequency hearing, suggesting that the convergent changes of the prestin function in echolocating mammals may play important roles in mammalian echolocation. To our knowledge, these findings present the functional patterns of echolocation-related genes in echolocating mammals for the first time and rigorously demonstrate adaptive parallel evolution at the protein sequence level, paving the way to insights into the molecular mechanism underlying mammalian echolocation. © The Author 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  1. Which Type of Risk Information to Use for Whom? Moderating Role of Outcome-Relevant Involvement in the Effects of Statistical and Exemplified Risk Information on Risk Perceptions.

    Science.gov (United States)

    So, Jiyeon; Jeong, Se-Hoon; Hwang, Yoori

    2017-04-01

    The extant empirical research examining the effectiveness of statistical and exemplar-based health information is largely inconsistent. Under the premise that the inconsistency may be due to an unacknowledged moderator (O'Keefe, 2002), this study examined a moderating role of outcome-relevant involvement (Johnson & Eagly, 1989) in the effects of statistical and exemplified risk information on risk perception. Consistent with predictions based on elaboration likelihood model (Petty & Cacioppo, 1984), findings from an experiment (N = 237) concerning alcohol consumption risks showed that statistical risk information predicted risk perceptions of individuals with high, rather than low, involvement, while exemplified risk information predicted risk perceptions of those with low, rather than high, involvement. Moreover, statistical risk information contributed to negative attitude toward drinking via increased risk perception only for highly involved individuals, while exemplified risk information influenced the attitude through the same mechanism only for individuals with low involvement. Theoretical and practical implications for health risk communication are discussed.

  2. INFORMATION SOCIETY EVOLUTION AND EFFECTS

    DEFF Research Database (Denmark)

    Brooks, Anthony Lewis

    2016-01-01

    The evolution and effects of the information society can be exemplified via many threads, both in hard and soft science, according to ones’ discipline and field. In this contribution, the speaker’s three decades of applied research acts as a vehicle to demonstrate development and impact via...... commercial product, national and international projects, and industry startups (including impactful third party research investigations) form the basis for discussion. Beyond this, a wider more generic perspective reflects on product adoption that illustrate todays’ contemporary e-society tendencies where...... recent influx and uptake of consumer-targeted artificial reality products point to society’s desire for alternative sensory experiences. Posited is how aligned with this desire there is a need for new ethical considerations in research as was found in the speaker’s research at the end of the 20th century...

  3. On lacunary statistical convergence of order α in probability

    Science.gov (United States)

    Işık, Mahmut; Et, Kübra Elif

    2015-09-01

    In this study, we examine the concepts of lacunary statistical convergence of order α in probability and Nθ—convergence of order α in probability. We give some relations connected to these concepts.

  4. Weaker conditions for the convergence of Newton's method

    National Research Council Canada - National Science Library

    Argyros, Ioannis K; Hilout, SaiD

    2012-01-01

    Newton's method is often used for solving nonlinear equations. In this paper, we show that Newton's method converges under weaker convergence criteria than those given in earlier studies, such as Argyros (2004...

  5. Convergent bacterial microbiotas in the fungal agricultural systems of insects.

    Science.gov (United States)

    Aylward, Frank O; Suen, Garret; Biedermann, Peter H W; Adams, Aaron S; Scott, Jarrod J; Malfatti, Stephanie A; Glavina del Rio, Tijana; Tringe, Susannah G; Poulsen, Michael; Raffa, Kenneth F; Klepzig, Kier D; Currie, Cameron R

    2014-11-18

    The ability to cultivate food is an innovation that has produced some of the most successful ecological strategies on the planet. Although most well recognized in humans, where agriculture represents a defining feature of civilization, species of ants, beetles, and termites have also independently evolved symbioses with fungi that they cultivate for food. Despite occurring across divergent insect and fungal lineages, the fungivorous niches of these insects are remarkably similar, indicating convergent evolution toward this successful ecological strategy. Here, we characterize the microbiota of ants, beetles, and termites engaged in nutritional symbioses with fungi to define the bacterial groups associated with these prominent herbivores and forest pests. Using culture-independent techniques and the in silico reconstruction of 37 composite genomes of dominant community members, we demonstrate that different insect-fungal symbioses that collectively shape ecosystems worldwide have highly similar bacterial microbiotas comprised primarily of the genera Enterobacter, Rahnella, and Pseudomonas. Although these symbioses span three orders of insects and two phyla of fungi, we show that they are associated with bacteria sharing high whole-genome nucleotide identity. Due to the fine-scale correspondence of the bacterial microbiotas of insects engaged in fungal symbioses, our findings indicate that this represents an example of convergence of entire host-microbe complexes. The cultivation of fungi for food is a behavior that has evolved independently in ants, beetles, and termites and has enabled many species of these insects to become ecologically important and widely distributed herbivores and forest pests. Although the primary fungal cultivars of these insects have been studied for decades, comparatively little is known of their bacterial microbiota. In this study, we show that diverse fungus-growing insects are associated with a common bacterial community composed of the

  6. Convergence Analysis for the Multiplicative Schwarz Preconditioned Inexact Newton Algorithm

    KAUST Repository

    Liu, Lulu

    2016-10-26

    The multiplicative Schwarz preconditioned inexact Newton (MSPIN) algorithm, based on decomposition by field type rather than by subdomain, was recently introduced to improve the convergence of systems with unbalanced nonlinearities. This paper provides a convergence analysis of the MSPIN algorithm. Under reasonable assumptions, it is shown that MSPIN is locally convergent, and desired superlinear or even quadratic convergence can be obtained when the forcing terms are picked suitably.

  7. Semilocal Convergence Analysis for Inexact Newton Method under Weak Condition

    Directory of Open Access Journals (Sweden)

    Xiubin Xu

    2012-01-01

    Full Text Available Under the hypothesis that the first derivative satisfies some kind of weak Lipschitz conditions, a new semilocal convergence theorem for inexact Newton method is presented. Unified convergence criteria ensuring the convergence of inexact Newton method are also established. Applications to some special cases such as the Kantorovich type conditions and γ-Conditions are provided and some well-known convergence theorems for Newton's method are obtained as corollaries.

  8. The Evolution of Agriculture in Insects

    DEFF Research Database (Denmark)

    Mueller, Ulrich G.; Gerardo, Nicole M.; Aanen, Duur Kornelis

    2005-01-01

    Agriculture has evolved independently in three insect orders: once in ants, once in termites, and seven times in ambrosia beetles. Although these insect farmers are in some ways quite different from each other, in many more ways they are remarkably similar, suggesting convergent evolution. All...

  9. Modelling Convergence of Finite Element Analysis of Cantilever Beam

    African Journals Online (AJOL)

    Convergence studies are carried out by investigating the convergence of numerical results as the number of elements is increased. If convergence is not obtained, the engineer using the finite element method has absolutely no indication whether the results are indicative of a meaningful approximation to the correct solution ...

  10. An Ensemble Approach in Converging Contents of LMS and KMS

    Science.gov (United States)

    Sabitha, A. Sai; Mehrotra, Deepti; Bansal, Abhay

    2017-01-01

    Currently the challenges in e-Learning are converging the learning content from various sources and managing them within e-learning practices. Data mining learning algorithms can be used and the contents can be converged based on the Metadata of the objects. Ensemble methods use multiple learning algorithms and it can be used to converge the…

  11. Understanding Spatiotemporal Patterns of Human Convergence and Divergence Using Mobile Phone Location Data

    Directory of Open Access Journals (Sweden)

    Xiping Yang

    2016-09-01

    Full Text Available Investigating human mobility patterns can help researchers and agencies understand the driving forces of human movement, with potential benefits for urban planning and traffic management. Recent advances in location-aware technologies have provided many new data sources (e.g., mobile phone and social media data for studying human space-time behavioral regularity. Although existing studies have utilized these new datasets to characterize human mobility patterns from various aspects, such as predicting human mobility and monitoring urban dynamics, few studies have focused on human convergence and divergence patterns within a city. This study aims to explore human spatial convergence and divergence and their evolutions over time using large-scale mobile phone location data. Using a dataset from Shenzhen, China, we developed a method to identify spatiotemporal patterns of human convergence and divergence. Eight distinct patterns were extracted, and the spatial distributions of these patterns are discussed in the context of urban functional regions. Thus, this study investigates urban human convergence and divergence patterns and their relationships with the urban functional environment, which is helpful for urban policy development, urban planning and traffic management.

  12. Statistical evaluation of the degree of nominal convergence of the inflation rate in Romania

    Directory of Open Access Journals (Sweden)

    Mihai GHEORGHE

    2011-07-01

    Full Text Available Nominal convergence is a process that is characterised by the gradual harmonisation, to a relatively high degree, of the national institutions and policies of the Member States with those of the EU, in the monetary and financial fields.The birth of nominal convergence is marked by the Maastricht Treaty, by means of which the criteria required for adopting the euro were established. One of the criteria refers to price stability (inflation rate, which is measured by the Harmonised Index of Consumer Prices. A Member State meets this criterion if it has a price performance that is sustainable and an average rate of inflation, observed over a period of one year before the examination,that does not exceed by more than 1.5 percentage point that of, at most, the three best performing Member States in terms of price stability.The article proposes a model for the statistical evaluation of the degree to which the nominal convergence criterion related to price stability is met. The evaluation is based on the following pillars: a theoretical synthesis of the Harmonised Index of Consumer Prices, a statistical analysis concerning the evolution of inflation in Romania and the gap vis-à-vis the reference value for meeting the nominal convergence criterion.

  13. Morphological evolution, ecological diversification and climate change in rodents.

    Science.gov (United States)

    Renaud, Sabrina; Michaux, Jacques; Schmidt, Daniela N; Aguilar, Jean-Pierre; Mein, Pierre; Auffray, Jean-Christophe

    2005-03-22

    Among rodents, the lineage from Progonomys hispanicus to Stephanomys documents a case of increasing size and dental specialization during an approximately 9 Myr time-interval. On the contrary, some contemporaneous generalist lineages like Apodemus show a limited morphological evolution. Dental shape can be related to diet and can be used to assess the ecological changes along the lineages. Consequently, size and shape of the first upper molar were measured in order to quantify the patterns of morphological evolution along both lineages and compare them to environmental trends. Climatic changes do not have a direct influence on evolution, but they open new ecological opportunities by changing vegetation and allow the evolution of a specialist like Stephanomys. On the other hand, environmental changes are not dramatic enough to destroy the habitat of a long-term generalist like Apodemus. Hence, our results exemplify a case of an influence of climate on the evolution of specialist species, although a generalist species may persist without change.

  14. Evolutionary conservatism and convergence both lead to striking similarity in ecology, morphology and performance across continents in frogs

    Science.gov (United States)

    Moen, Daniel S.; Irschick, Duncan J.; Wiens, John J.

    2013-01-01

    Many clades contain ecologically and phenotypically similar species across continents, yet the processes generating this similarity are largely unstudied, leaving fundamental questions unanswered. Is similarity in morphology and performance across assemblages caused by evolutionary convergence or by biogeographic dispersal of evolutionarily conserved ecotypes? Does convergence to new ecological conditions erase evidence of past adaptation? Here, we analyse ecology, morphology and performance in frog assemblages from three continents (Asia, Australia and South America), assessing the importance of dispersal and convergent evolution in explaining similarity across regions. We find three striking results. First, species using the same microhabitat type are highly similar in morphology and performance across both clades and continents. Second, some species on different continents owe their similarity to dispersal and evolutionary conservatism (rather than evolutionary convergence), even over vast temporal and spatial scales. Third, in one case, an ecologically specialized ancestor radiated into diverse ecotypes that have converged with those on other continents, largely erasing traces of past adaptation to their ancestral ecology. Overall, our study highlights the roles of both evolutionary conservatism and convergence in explaining similarity in species traits over large spatial and temporal scales and demonstrates a statistical framework for addressing these questions in other systems. PMID:24174109

  15. Convergence of knowledge, technology and society beyond convergence of nano-bio-info-cognitive technologies

    CERN Document Server

    Bainbridge, William; Tonn, Bruce; Whitesides, George

    2013-01-01

    Convergence of knowledge and technology for the benefit of society (CKTS) is the core opportunity for progress in the 21st century, based on five principles: (1) the interdependence of all components of nature and society, (2) enhancement of creativity and innovation through evolutionary processes of convergence that combine existing principles, and divergence that generates new ones, (3) decision analysis for research and development based on system-logic deduction, (4) higher-level cross-domain languages to generate new solutions and support transfer of new knowledge, and (5) vision-inspired basic research embodied in grand challenges. Solutions are outlined for key societal challenges, including creating new industries and jobs, improving lifelong wellness and human potential, achieving personalized and integrated healthcare and education, and securing a sustainable quality of life for all. This report provides a ten-year “NBIC2” vision within a longer-term framework for converging technology and human...

  16. A Globally Convergent Matrix-Free Method for Constrained Equations and Its Linear Convergence Rate

    Directory of Open Access Journals (Sweden)

    Min Sun

    2014-01-01

    Full Text Available A matrix-free method for constrained equations is proposed, which is a combination of the well-known PRP (Polak-Ribière-Polyak conjugate gradient method and the famous hyperplane projection method. The new method is not only derivative-free, but also completely matrix-free, and consequently, it can be applied to solve large-scale constrained equations. We obtain global convergence of the new method without any differentiability requirement on the constrained equations. Compared with the existing gradient methods for solving such problem, the new method possesses linear convergence rate under standard conditions, and a relax factor γ is attached in the update step to accelerate convergence. Preliminary numerical results show that it is promising in practice.

  17. Convergent losses of decay mechanisms and rapid turnover of symbiosis genes in mycorrhizal mutualists.

    Science.gov (United States)

    Kohler, Annegret; Kuo, Alan; Nagy, Laszlo G; Morin, Emmanuelle; Barry, Kerrie W; Buscot, Francois; Canbäck, Björn; Choi, Cindy; Cichocki, Nicolas; Clum, Alicia; Colpaert, Jan; Copeland, Alex; Costa, Mauricio D; Doré, Jeanne; Floudas, Dimitrios; Gay, Gilles; Girlanda, Mariangela; Henrissat, Bernard; Herrmann, Sylvie; Hess, Jaqueline; Högberg, Nils; Johansson, Tomas; Khouja, Hassine-Radhouane; LaButti, Kurt; Lahrmann, Urs; Levasseur, Anthony; Lindquist, Erika A; Lipzen, Anna; Marmeisse, Roland; Martino, Elena; Murat, Claude; Ngan, Chew Y; Nehls, Uwe; Plett, Jonathan M; Pringle, Anne; Ohm, Robin A; Perotto, Silvia; Peter, Martina; Riley, Robert; Rineau, Francois; Ruytinx, Joske; Salamov, Asaf; Shah, Firoz; Sun, Hui; Tarkka, Mika; Tritt, Andrew; Veneault-Fourrey, Claire; Zuccaro, Alga; Tunlid, Anders; Grigoriev, Igor V; Hibbett, David S; Martin, Francis

    2015-04-01

    To elucidate the genetic bases of mycorrhizal lifestyle evolution, we sequenced new fungal genomes, including 13 ectomycorrhizal (ECM), orchid (ORM) and ericoid (ERM) species, and five saprotrophs, which we analyzed along with other fungal genomes. Ectomycorrhizal fungi have a reduced complement of genes encoding plant cell wall-degrading enzymes (PCWDEs), as compared to their ancestral wood decayers. Nevertheless, they have retained a unique array of PCWDEs, thus suggesting that they possess diverse abilities to decompose lignocellulose. Similar functional categories of nonorthologous genes are induced in symbiosis. Of induced genes, 7-38% are orphan genes, including genes that encode secreted effector-like proteins. Convergent evolution of the mycorrhizal habit in fungi occurred via the repeated evolution of a 'symbiosis toolkit', with reduced numbers of PCWDEs and lineage-specific suites of mycorrhiza-induced genes.

  18. A Quadratically Convergent O(square root of nL-Iteration Algorithm for Linear Programming

    National Research Council Canada - National Science Library

    Ye, Y; Gueler, O; Tapia, Richard A; Zhang, Y

    1991-01-01

    ...)-iteration complexity while exhibiting superlinear convergence of the duality gap to zero under the assumption that the iteration sequence converges, and quadratic convergence of the duality gap...

  19. Convergent strabismus in a white Bengal tiger.

    Science.gov (United States)

    Bernays, M E; Smith, R I

    1999-03-01

    A white Bengal tiger was noted to have a convergent strabismus with poor vision since a cub. The tiger and a littermate with normal colouring and apparently normal eyes were anaesthetised for comparative ocular examination. A fundus typical of colour-dilute cats and dogs was noted in the white tiger. Except for strabismus, no abnormalities were observed. Electroretinography showed similar retinal function in both tigers. Possible causes of strabismus considered were an adaptation to genetically determined abnormal visual pathways related to lack of pigment, abnormalities of the abducent nerves and mechanical restricting conditions of the medial rectus muscles.

  20. Ultraslow convergence to ergodicity in transient subdiffusion.

    Science.gov (United States)

    Miyaguchi, Tomoshige; Akimoto, Takuma

    2011-06-01

    We investigate continuous time random walks with truncated α-stable trapping times. We prove distributional ergodicity for a class of observables; namely, the time-averaged observables follow the probability density function called the Mittag-Leffler distribution. This distributional ergodic behavior persists for a long time, and thus the convergence to the ordinary ergodicity is considerably slower than in the case in which the trapping-time distribution is given by common distributions. We also find a crossover from the distributional ergodic behavior to the ordinary ergodic behavior.

  1. FDI, Human Capital and Income Convergence

    DEFF Research Database (Denmark)

    Völlmecke, Dominik; Jindra, Björn; Marek, Philipp

    2016-01-01

    This study examines income convergence in regional GDP per capita for a sample of 269 regions within the European Union (EU) between 2003 and 2010. We use an endogenous broad capital model based on foreign direct investment (FDI) induced agglomeration economies and human capital. By applying...... within Central and East European countries (CEECs), where we find indications of a poverty trap. In contrast to FDI, regional human capital seems to be associated with higher income levels. However, we identify a positive interaction of FDI and human capital in their relation with income growth dynamics....

  2. Rates of Convergence of Recursively Defined Sequences

    DEFF Research Database (Denmark)

    Lambov, Branimir Zdravkov

    2005-01-01

    This paper gives a generalization of a result by Matiyasevich which gives explicit rates of convergence for monotone recursively defined sequences. The generalization is motivated by recent developments in fixed point theory and the search for applications of proof mining to the field. It relaxes...... the requirement for monotonicity to the form xn+1 ≤ (1+an)xn+bn where the parameter sequences have to be bounded in sum, and also provides means to treat computational errors. The paper also gives an example result, an application of proof mining to fixed point theory, that can be achieved by the means discussed...

  3. Drug-Driven Phenotypic Convergence Supports Rational Treatment Strategies of Chronic Infections

    DEFF Research Database (Denmark)

    Imamovic, Lejla; Ellabaan, Mostafa Mostafa Hashim; Dantas Machado, Ana Manuel

    2018-01-01

    Chronic Pseudomonas aeruginosa infections evade antibiotic therapy and are associated with mortality in cystic fibrosis (CF) patients. We find that in vitro resistance evolution of P. aeruginosa toward clinically relevant antibiotics leads to phenotypic convergence toward distinct states....... These states are associated with collateral sensitivity toward several antibiotic classes and encoded by mutations in antibiotic resistance genes, including transcriptional regulator nfxB. Longitudinal analysis of isolates from CF patients reveals similar and defined phenotypic states, which are associated...... with extinction of specific sub-lineages in patients. In-depth investigation of chronic P. aeruginosa populations in a CF patient during antibiotic therapy revealed dramatic genotypic and phenotypic convergence. Notably, fluoroquinolone-resistant subpopulations harboring nfxB mutations were eradicated...

  4. Large Time Behavior and Convergence Rate for Quantum Filters Under Standard Non Demolition Conditions

    Science.gov (United States)

    Benoist, Tristan; Pellegrini, Clément

    2014-10-01

    A quantum system undergoing continuous time measurement is usually described by a jump-diffusion stochastic differential equation. Such an equation is called a quantum filtering equation (or quantum stochastic master equation) and its solution is called a quantum filter (or quantum trajectory). This solution describes the evolution of the state of . In the context of quantum non demolition measurement, we investigate the large time behavior of this solution. It is rigorously shown that, for large time, this solution behaves as if a direct Von Neumann measurement has been performed at time 0. In particular the solution converges to a random pure state which can be directly linked to the wave packet reduction postulate. Using the theory of Girsanov transformation, we obtain the explicit rate of convergence towards this random state. The problem of state estimation (used in experiment) is also investigated.

  5. Converging social classes through humanized urban edges

    Science.gov (United States)

    Abuan, M. V.; Galingan, Z. D.

    2017-10-01

    Urban open spaces are created to be used by people. It is a place of convergence and social activity. However, these places have transformed into places of divergence. When spaces become dehumanized, it separates social classes. As a result, underused spaces contribute to urban decay. Particularly an urban edge, the JP Rizal Makati Waterfront Area is the center of this paper. The JP Rizal Makati Waterfront Area is a waterfront development situated along the banks of one of Metro Manila’s major water thoroughfare --- Pasig River. The park and its physical form, urban design and landscape tend to deteriorate over time --- creating a further division of social convergence. Social hostility, crime, negligent maintenance and poor urban design are contributing factors to this sprawling decay in what used to be spaces of bringing people together. Amidst attempts to beautify and renew this portion of Makati City’s edge, the urban area still remains misspent.This paper attempts to re-humanize the waterfront development. It uses the responsive environment design principles to be able to achieve this goal.

  6. Convergences in the diversification of bats

    Directory of Open Access Journals (Sweden)

    M. Brock FENTON

    2010-08-01

    Full Text Available Twenty-five characters or suites of characters from bats are considered in light of changes in bat classification. The characters include some associated with flower-visiting (two, echolocation (12, roosting (six, reproduction (two and three are of unknown adaptive function. In both the 1998 and 2006 classifications of bats into suborders (Megachiroptera and Microchiroptera versus Yinpterochiroptera and Yangochiroptera, respectively, some convergences between suborders are the same (e.g., foliage roosting, tent building, but others associated with echolocation differ substantially. In the 1998 phylogeny convergences associated with echolocation (high duty cycle echolocation, nasal emission of echolocation calls occurred among the Microchiroptera. In the 2006 phylogeny, they occur between Yinpterochiroptera and Yangochiroptera. While some traits apparently arose independently in two suborders (e.g., foliage-roosting, tent building, low intensity echolocation calls, noseleafs, nasal emission of echolocation calls, high duty cycle echolocation behaviour, others appear to have been ancestral (roosting in narrow spaces, laryngeal echolocation, stylohyal-tympanic contact, oral emission of echolocation calls, and small litter size. A narrow profile through the chest is typical of bats reflecting the thoracic skeleton. This feature suggests that the ancestors of bats spent the day in small crevices. Features associated with laryngeal echolocation appear to be ancestral, suggesting that echolocation evolved early in bats but was subsequently lost in one yinpterochiropteran lineage [Current Zoology 56 (4: 454–468, 2010].

  7. Symbolic convergence and the hydrogen economy

    Energy Technology Data Exchange (ETDEWEB)

    Sovacool, Benjamin K. [Lee Kuan Yew School of Public Policy, 469C Bukit Timah Road, National University of Singapore, Singapore 259772 (Singapore); Brossmann, Brent [Tim Russert Department of Communication and Theatre Arts, O' Malley Center Room 59, John Carroll University, 20700 North Park Boulevard, Cleveland, OH 44118 (United States)

    2010-04-15

    This article documents that the hydrogen economy continues to attract significant attention among politicians, the media, and some academics. We believe that an explanation lies in the way that the hydrogen economy fulfills psychological and cultural needs related to a future world where energy is abundant, cheap, and pollution-free, a 'fantasy' that manifests itself with the idea that society can continue to operate without limits imposed by population growth and the destruction of the environment. The article begins by explaining its research methodology consisting of two literature reviews, research interviews of energy experts, and the application of symbolic convergence theory, a general communications theory about the construction of rhetorical fantasies. We then identify a host of socio-technical challenges to explain why the creation of a hydrogen economy would present immense (and possibly intractable) obstacles, an argument supplemented by our research interviews. Next, we employ symbolic convergence theory to identify five prevalent fantasy themes and rhetorical visions - independence, patriotism, progress, democratization, and inevitability - in academic and public discussions in favor of the hydrogen economy. We conclude by offering implications for scholarship relating to energy policy more broadly. (author)

  8. CONVERGENCE IN THE EUROPEAN SOCIAL POLICY

    Directory of Open Access Journals (Sweden)

    Mariana Iovitu

    2012-07-01

    Full Text Available The European Union has developed a series of strategies that aim to limit the consequences of non-employment (due to the continuing crisis. These strategies aim by the objectives and mechanisms specific to the eco-social area, to improve the access to employment, social services, professional education and a more efficient European fund management. All this are subordinated to the coupling policy public-private in terms of partnerships both at a national level and European level. The problem is related to differences manifested between the social objectives at the national level and those imposed by the European context. The differences come from different degrees of economic development of the member states, economic development which is reflected on the living standards. The convergence between the social policies is based on the economic convergence, which represents the only way to ameliorate the discrepancies between the united nations of Europe. Social Europe dream or certainty? The answer can be found in the words of Jean Monnet: “we are not bringing together states, we are uniting people”. The efforts to define the four types of actions regarding the free movement of labor force and the correlation of the social security schemes, ensuring equal opportunities, respecting labor rights and the fight against discrimination can be found in the results obtained on these priorities.

  9. Convergence of some leader election algorithms

    Directory of Open Access Journals (Sweden)

    Svante Janson

    2008-08-01

    Full Text Available We start with a set of n players. With some probability P(n,k, we kill n-k players; the other ones stay alive, and we repeat with them. What is the distribution of the number X n of phases (or rounds before getting only one player? We present a probabilistic analysis of this algorithm under some conditions on the probability distributions P(n,k, including stochastic monotonicity and the assumption that roughly a fixed proportion α of the players survive in each round. We prove a kind of convergence in distribution for X n - log 1/α n; as in many other similar problems there are oscillations and no true limit distribution, but suitable subsequences converge, and there is an absolutely continuous random variable Z such that d(X n, ⌈Z+ log 1/α n⌉→0, where d is either the total variation distance or the Wasserstein distance. Applications of the general result include the leader election algorithm where players are eliminated by independent coin tosses and a variation of the leader election algorithm proposed by W.R. Franklin 1982. We study the latter algorithm further, including numerical results.

  10. Accelerating evaluation of converged lattice thermal conductivity

    Science.gov (United States)

    Qin, Guangzhao; Hu, Ming

    2018-01-01

    High-throughput computational materials design is an emerging area in materials science, which is based on the fast evaluation of physical-related properties. The lattice thermal conductivity (κ) is a key property of materials for enormous implications. However, the high-throughput evaluation of κ remains a challenge due to the large resources costs and time-consuming procedures. In this paper, we propose a concise strategy to efficiently accelerate the evaluation process of obtaining accurate and converged κ. The strategy is in the framework of phonon Boltzmann transport equation (BTE) coupled with first-principles calculations. Based on the analysis of harmonic interatomic force constants (IFCs), the large enough cutoff radius (rcutoff), a critical parameter involved in calculating the anharmonic IFCs, can be directly determined to get satisfactory results. Moreover, we find a simple way to largely ( 10 times) accelerate the computations by fast reconstructing the anharmonic IFCs in the convergence test of κ with respect to the rcutof, which finally confirms the chosen rcutoff is appropriate. Two-dimensional graphene and phosphorene along with bulk SnSe are presented to validate our approach, and the long-debate divergence problem of thermal conductivity in low-dimensional systems is studied. The quantitative strategy proposed herein can be a good candidate for fast evaluating the reliable κ and thus provides useful tool for high-throughput materials screening and design with targeted thermal transport properties.

  11. Adaptation Technique in the Translation of Literary Texts (as Exemplified in the Translation of French and English Literary Texts

    Directory of Open Access Journals (Sweden)

    Полина Сергеевна Тасенко

    2016-12-01

    Full Text Available This article describes some particularities of translation of literary texts from French and English into Russian as exemplified in the novel “The Lady of the Camellias” by A. Dumas and the novel “Wuthering Heights” by E. Brontë. The article examines in particular the use of the adaptation technique in order to confirm the hypothesis of the connection of this translation transformation with conveyance of the original's stylistic features. This transformation is applied in the translation of some phenomena and phrases in the original text that can barely be translated because of their national singularity, a significant time gap, or peculiarity for other culture bearers. The theoretical foundation for the article are literary style researches [Barkhudarov, 1975; Komissarov, 1990; Chaikovskij, 1997; Chukovskij, 2014; Baker, 2011], as well as researches in the field of the use of adaptation in the translation of literary texts [Alekseeva, 2004; Vlakhov, Florin, 1980; Shchetinkin, 1987; Clifford, Landers, 2001; Newmark, 1988]. The research methods used in the study are the following: relevant scientific literature analysis, statistical approach, comparative study of literary texts and their translations. A thorough analysis of the nature of adaptation enabled us to specify a range of translation transformations which allow adaptation to be applied in the reanslation of literary texts. According to the results of the research, the informative as well as the aesthetic function plays a very important role in the translation of literary texts.

  12. Delimitation of Areas of Environmental Conflicts on the Background of Geological Conditions, Exemplified by Stary Sącz Commune

    Directory of Open Access Journals (Sweden)

    Gałaś Slávka

    2014-12-01

    Full Text Available Delimitation and characterization of areas of conflict are essential to assess suitability of land for different activities carried out in the field of rational land use. In the paper, delimitation of the conflict areas and conflicts categorization in terms of possibility of their overcoming, the scale of the range and the period of their occurrence exemplified by urban - rural commune Stary Sącz have been presented. The software ArcGIS 10.1, the method of maps superimposing and analysis of interactions between different geoenvironmental factors have been applied to obtain the goal of the investigation. Specific geological structure together with morphological and climatic conditions in Stary Sącz commune create ideal conditions for occurrence of con-flict areas on the background of the geological conditions. Accurate and early recognition of these conflicts - existing and potential ones, is a prerequisite for the environmental risk prevention and elimination of its effects through the proper preparation of planning documents and development plans and programs.

  13. The use of network analysis in the process of delimitation as exemplifi ed by the administrative division of Poland

    Science.gov (United States)

    Borowska-Stefańska, Marta; Wiśniewski, Szymon

    2017-12-01

    The cognitive aim of this study is to point to the optimum number of local government units and the optimum boundaries of spatial units in Poland with the assumption of minimizing the cumulated theoretical travel time to all settlement units in the country. The methodological aim, in turn, is to present the use of the ArcGIS location-allocation tool for the purposes of delimitation processes as exemplifi ed by administrative boundaries in Poland. The rationale for the implementation of this study is that number and the boundaries of units of all levels of Poland's current territorial division are far from optimum in the light of minimization of accumulated theoretical travel time to all settlement units in the country. It may be concluded that it would be justifi able to increase the number of voivodships from the current number of 16 to 18. Besides it would be necessary to introduce modifi cations in relation to units with regional functions. In contrast, the number of districts and communes should be reduced. A continuation of this research may go in the direction of including analysis of public transport network in the research, creating in this way a multimodal set of network data. This would illustrate, apart from the potential itself resulting from the infrastructure, also the actually existing connections.

  14. The use of network analysis in the process of delimitation as exemplifi ed by the administrative division of Poland

    Directory of Open Access Journals (Sweden)

    Borowska-Stefańska Marta

    2017-12-01

    Full Text Available The cognitive aim of this study is to point to the optimum number of local government units and the optimum boundaries of spatial units in Poland with the assumption of minimizing the cumulated theoretical travel time to all settlement units in the country. The methodological aim, in turn, is to present the use of the ArcGIS location-allocation tool for the purposes of delimitation processes as exemplifi ed by administrative boundaries in Poland. The rationale for the implementation of this study is that number and the boundaries of units of all levels of Poland’s current territorial division are far from optimum in the light of minimization of accumulated theoretical travel time to all settlement units in the country. It may be concluded that it would be justifi able to increase the number of voivodships from the current number of 16 to 18. Besides it would be necessary to introduce modifi cations in relation to units with regional functions. In contrast, the number of districts and communes should be reduced. A continuation of this research may go in the direction of including analysis of public transport network in the research, creating in this way a multimodal set of network data. This would illustrate, apart from the potential itself resulting from the infrastructure, also the actually existing connections.

  15. Formation and Initiation of Erupting Flux Rope and Embedded Filament Driven by Photospheric Converging Motion

    Science.gov (United States)

    Zhao, Xiaozhou; Xia, Chun; Keppens, Rony; Gan, Weiqun

    2017-06-01

    In this paper, we study how a flux rope (FR) is formed and evolves into the corresponding structure of a coronal mass ejection (CME) numerically driven by photospheric converging motion. A two-and-a-half-dimensional magnetohydrodynamics simulation is conducted in a chromosphere-transition-corona setup. The initial arcade-like linear force-free magnetic field is driven by an imposed slow motion converging toward the magnetic inversion line at the bottom boundary. The convergence brings opposite-polarity magnetic flux to the polarity inversion, giving rise to the formation of an FR by magnetic reconnection and eventually to the eruption of a CME. During the FR formation, an embedded prominence gets formed by the levitation of chromospheric material. We confirm that the converging flow is a potential mechanism for the formation of FRs and a possible triggering mechanism for CMEs. We investigate the thermal, dynamical, and magnetic properties of the FR and its embedded prominence by tracking their thermal evolution, analyzing their force balance, and measuring their kinematic quantities. The phase transition from the initiation phase to the acceleration phase of the kinematic evolution of the FR was observed in our simulation. The FR undergoes a series of quasi-static equilibrium states in the initiation phase; while in the acceleration phase the FR is driven by Lorentz force and the impulsive acceleration occurs. The underlying physical reason for the phase transition is the change of the reconnection mechanism from the Sweet-Parker to the unsteady bursty regime of reconnection in the evolving current sheet underneath the FR.

  16. The Analysis of the Real Convergence of the Countries from Central and Eastern Europe

    Directory of Open Access Journals (Sweden)

    Roxana Badircea

    2016-11-01

    Full Text Available This thesis treats extremely present aspects regarding the evolutions of the emerging economies within the new member states of the European Union insisting on the analysis of the convergence process from a real perspective. Beside the achievement of a monetary union, one of the fundamental objectives of the European Union is represented by the reducing of the disparities regarding the level of development among the member states. One of the ways of appreciating the reduction of the disparities between the economies involve a reduction of the gap as far as the GDP level/inhabitant is concerned or in other words, a real convergence. A series of statistic data are analysed in order to point out the extent to which the central ad East-European states have managed to reduce the gap in report to the developed member states of the EMU, using indicators for the appreciation of the real convergence: the GDP per inhabitant, the monthly average salary, the poverty rate, the contribution of the main sectors of the economy in the formation of the GDP and the unemployment rate. From the analysis of the statistic data one can observe that the highest degree of real convergence is held by Slovenia, which distanced a lot from the other EEC states, followed by the Czech Republic. Regarding from the point of view of the evolution of the EEC countries during the entire analysed period, based on the dynamics of the indicators and of the speed of catching up the gaps we can also notice the performance of the Baltic countries. Unfortunately, Romania and Bulgaria are way behind the other EEC countries.

  17. The Analysis of the Real Convergence of the Countries from Central and Eastern Europe

    Directory of Open Access Journals (Sweden)

    Roxana Maria Bădîrcea

    2016-11-01

    Full Text Available This thesis treats extremely present aspects regarding the evolutions of the emerging economies within the new member states of the European Union insisting on the analysis of the convergence process from a real perspective. Beside the achievement of a monetary union, one of the fundamental objectives of the European Union is represented by the reducing of the disparities regarding the level of development among the member states. One of the ways of appreciating the reduction of the disparities between the economies involve a reduction of the gap as far as the GDP level/inhabitant is concerned or in other words, a real convergence. A series of statistic data are analysed in order to point out the extent to which the central and East-European states have managed to reduce the gap in report to the developed member states of the EMU, using indicators for the appreciation of the real convergence: the GDP per inhabitant, the monthly average salary, the poverty rate, the contribution of the main sectors of the economy in the formation of the GDP and the unemployment rate. From the analysis of the statistic data one can observe that the highest degree of real convergence is held by Slovenia, which distanced a lot from the other EEC states, followed by the Czech Republic. Regarding from the point of view of the evolution of the EEC countries during the entire analysed period, based on the dynamics of the indicators and of the speed of catching up the gaps we can also notice the performance of the Baltic countries. Unfortunately, Romania and Bulgaria are way behind the other EEC countries.

  18. Evolution, insular restriction, and extinction of oceanic land crabs, exemplified by the loss of an endemic Geograpsus in the Hawaiian Islands.

    Science.gov (United States)

    Paulay, Gustav; Starmer, John

    2011-01-01

    Most oceanic islands harbor unusual and vulnerable biotas as a result of isolation. As many groups, including dominant competitors and predators, have not naturally reached remote islands, others were less constrained to evolve novel adaptations and invade adaptive zones occupied by other taxa on continents. Land crabs are an excellent example of such ecological release, and some crab lineages made the macro-evolutionary transition from sea to land on islands. Numerous land crabs are restricted to, although widespread among, oceanic islands, where they can be keystone species in coastal forests, occupying guilds filled by vertebrates on continents. In the remote Hawaiian Islands, land crabs are strikingly absent. Here we show that absence of land crabs in the Hawaiian Islands is the result of extinction, rather than dispersal limitation. Analysis of fossil remains from all major islands show that an endemic Geograpsus was abundant before human colonization, grew larger than any congener, and extended further inland and to higher elevation than other land crabs in Oceania. Land crabs are major predators of nesting sea birds, invertebrates and plants, affect seed dispersal, control litter decomposition, and are important in nutrient cycling; their removal can lead to large-scale shifts in ecological communities. Although the importance of land crabs is obvious on remote and relatively undisturbed islands, it is less apparent on others, likely because they are decimated by humans and introduced biota. The loss of Geograpsus and potentially other land crabs likely had profound consequences for Hawaiian ecosystems.

  19. Evolution, insular restriction, and extinction of oceanic land crabs, exemplified by the loss of an endemic Geograpsus in the Hawaiian Islands.

    Directory of Open Access Journals (Sweden)

    Gustav Paulay

    Full Text Available Most oceanic islands harbor unusual and vulnerable biotas as a result of isolation. As many groups, including dominant competitors and predators, have not naturally reached remote islands, others were less constrained to evolve novel adaptations and invade adaptive zones occupied by other taxa on continents. Land crabs are an excellent example of such ecological release, and some crab lineages made the macro-evolutionary transition from sea to land on islands. Numerous land crabs are restricted to, although widespread among, oceanic islands, where they can be keystone species in coastal forests, occupying guilds filled by vertebrates on continents. In the remote Hawaiian Islands, land crabs are strikingly absent. Here we show that absence of land crabs in the Hawaiian Islands is the result of extinction, rather than dispersal limitation. Analysis of fossil remains from all major islands show that an endemic Geograpsus was abundant before human colonization, grew larger than any congener, and extended further inland and to higher elevation than other land crabs in Oceania. Land crabs are major predators of nesting sea birds, invertebrates and plants, affect seed dispersal, control litter decomposition, and are important in nutrient cycling; their removal can lead to large-scale shifts in ecological communities. Although the importance of land crabs is obvious on remote and relatively undisturbed islands, it is less apparent on others, likely because they are decimated by humans and introduced biota. The loss of Geograpsus and potentially other land crabs likely had profound consequences for Hawaiian ecosystems.

  20. The evolution and functional divergence of the beta-carotene oxygenase gene family in teleost fish--exemplified by Atlantic salmon.

    Science.gov (United States)

    Helgeland, Hanna; Sandve, Simen Rød; Torgersen, Jacob Seilø; Halle, Mari Kyllesø; Sundvold, Hilde; Omholt, Stig; Våge, Dag Inge

    2014-06-15

    In mammals, two carotenoid cleaving oxygenases are known; beta-carotene 15,15'-monooxygenase (BCMO1) and beta-carotene 9',10'-oxygenase (BCO2). BCMO1 is a key enzyme in vitamin A synthesis by symmetrically cleaving beta-carotene into 2 molecules of all-trans-retinal, while BCO2 is responsible for asymmetric cleavage of a broader range of carotenoids. Here, we show that the Atlantic salmon beta-carotene oxygenase (bco) gene family contains 5 members, three bco2 and two bcmo1 paralogs. Using public sequence databases, multiple bco genes were also found in several additional teleost species. Phylogenetic analysis indicates that bco2a and bco2b originate from the teleost fish specific genome duplication (FSGD or 3R), while the third and more distant paralog, bco2 like, might stem from a prior duplication event in the teleost lineage. The two bcmo1 paralogs (bcmo1 and bcmo1 like) appear to be the result of an ancient duplication event that took place before the divergence of ray-finned (Actinopterygii) and lobe-finned fish (Sarcopterygii), with subsequent nonfunctionalization and loss of one Sarcopterygii paralog. Gene expression analysis of the bcmo1 and bco2 paralogs in Atlantic salmon reveals regulatory divergence with tissue specific expression profiles, suggesting that the beta-carotene oxygenase subtypes have evolved functional divergences. We suggest that teleost fish have evolved and maintained an extended repertoire of beta-carotene oxygenases compared to the investigated Sarcopterygii species, and hypothesize that the main driver behind this functional divergence is the exposure to a diverse set of carotenoids in the aquatic environment. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Real Economic Convergence in Western Europe from 1995 to 2013

    Directory of Open Access Journals (Sweden)

    Dzenita Siljak

    2016-05-01

    Full Text Available The aim of the paper is to analyze the economic convergence of real per capita GDP in the Western European countries with two types of measurement methodology. The first is sigma convergence, based on the coefficient of variation of real per capita GDP. The second is beta convergence, absolute/unconditional and conditional, including economic and socio-political variables, based on the neoclassical growth theory. The hypothesis of the paper is that there has been real economic convergence in Western Europe in at least one analyzed sub-period. The relationships between selected macroeconomic variables and the rate of economic growth are econometrically tested. Both sigma and beta convergence are estimated for the period 1995-2013 and four sub-periods: 1995-2003, 2004-2013, pre-crisis sub-period 2004-2008 and the crisis sub-period 2009-2013. The empirical findings support the hypothesis of economic convergence, i.e. that the poorer countries tend to grow faster than the rich ones in per capita terms, for some periods. However, the countries had a tendency to diverge, confiriming the negative effects of the crisis on per capita GDP growth. Sigma convergence is consistent with beta convergence. According to the results, the half-life of real convergence may take from 12 to 1078 years. Significant dissimilarities between the growth patterns among individual countries show the considerable heterogeneity of growth, i.e. the convergence clubs.

  2. Reduced vergence adaptation is associated with a prolonged output of convergence accommodation in convergence insufficiency.

    Science.gov (United States)

    Sreenivasan, Vidhyapriya; Bobier, William R

    2014-07-01

    Convergence insufficiency (CI) is a developmental visual anomaly defined clinically by a reduced near point of convergence, a reduced capacity to view through base-out prisms (fusional convergence); coupled with asthenopic symptoms typically blur and diplopia. Experimental studies show reduced vergence parameters and tonic adaptation. Based upon current models of accommodation and vergence, we hypothesize that the reduced vergence adaptation in CI leads to excessive amounts of convergence accommodation (CA). Eleven CI participants (mean age=17.4±2.3 years) were recruited with reduced capacity to view through increasing magnitudes of base out (BO) prisms (mean fusional convergence at 40 cm=12±0.9Δ). Testing followed our previous experimental design for (n=11) binocularly normal adults. Binocular fixation of a difference of Gaussian (DoG) target (0.2 cpd) elicited CA responses during vergence adaptation to a 12Δ BO. Vergence and CA responses were obtained at 3 min intervals over a 15 min period and time course were quantified using exponential decay functions. Results were compared to previously published data on eleven binocular normals. Eight participants completed the study. CI's showed significantly reduced magnitude of vergence adaptation (CI: 2.9Δ vs. normals: 6.6Δ; p=0.01) and CA reduction (CI=0.21 D, Normals=0.55 D; p=0.03). However, the decay time constants for adaptation and CA responses were not significantly different. CA changes were not confounded by changes in tonic accommodation (Change in TA=0.01±0.2D; p=0.8). The reduced magnitude of vergence adaptation found in CI patients resulting in higher levels of CA may potentially explain their clinical findings of reduced positive fusional vergence (PFV) and the common symptom of blur. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. AN ANALYSIS OF THE FISCAL CONVERGENCE CRITERIA IN THE EUROPEAN UNION IN TERMS OF THE SUSTAINABILITY

    Directory of Open Access Journals (Sweden)

    Iulia Andreea Bucur

    2014-01-01

    Full Text Available Although the convergence criteria in the Maastricht Treaty led to the creation of the EMU and the euro area has resisted more than some of its critics believed, in the context of major macroeconomic imbalances, the issue of nominal convergence has been the subject of numerous research. This paper aims to analyze the capacity of fiscal criteria to reflect the ability of EU Member States to achieve economic development for the integration in the EMU and to comply strict fiscal policy that governing its operation. In the context of certain technical deficiencies of fiscal criteria, we analyzed the developments of budget deficit and gross public debt in the EU during 2000 and 2012. The results show that until 2007 the EU economies were able, overall, to meet the budget deficit criteria, but due to the financial crisis and the prolonged slowdown in economic growth, the fiscal balance had an unfavorable evolution since 2008, while the evolution of the gross public debt has worsened increasingly. Due to this pressure situation on the sustainability of public finances, examining the adoption, application and enforcement of the fiscal policy rules expressed by the evolution of the Fiscal Rule Index for the period 2000-2011, the importance of rules in the fiscal management of the Union and especially of the euro area appears increasingly obvious.

  4. Converging intracranial markers of conscious access.

    Directory of Open Access Journals (Sweden)

    Raphaël Gaillard

    2009-03-01

    Full Text Available We compared conscious and nonconscious processing of briefly flashed words using a visual masking procedure while recording intracranial electroencephalogram (iEEG in ten patients. Nonconscious processing of masked words was observed in multiple cortical areas, mostly within an early time window (<300 ms, accompanied by induced gamma-band activity, but without coherent long-distance neural activity, suggesting a quickly dissipating feedforward wave. In contrast, conscious processing of unmasked words was characterized by the convergence of four distinct neurophysiological markers: sustained voltage changes, particularly in prefrontal cortex, large increases in spectral power in the gamma band, increases in long-distance phase synchrony in the beta range, and increases in long-range Granger causality. We argue that all of those measures provide distinct windows into the same distributed state of conscious processing. These results have a direct impact on current theoretical discussions concerning the neural correlates of conscious access.

  5. Flow of foam through a convergent channel.

    Science.gov (United States)

    Dollet, Benjamin; Bocher, Claire

    2015-11-01

    We study experimentally the flow of a foam confined as a bubble monolayer between two plates through a convergent channel. We quantify the velocity, the distribution and orientation of plastic events, and the elastic stress, using image analysis. We use two different soap solutions: a sodium dodecyl sulfate (SDS) solution, with a negligible wall friction between the bubbles and the confining plates, and a mixture containing a fatty acid, giving a large wall friction. We show that for SDS solutions, the velocity profile obeys a self-similar form which results from the superposition of plastic events, and the elastic deformation is uniform. For the other solution, the velocity field differs and the elastic deformation increases towards the exit of the channel. We discuss and quantify the role of wall friction on the velocity profile, the elastic deformation, and the rate of plastic events.

  6. [The syndrome of Capgras: converging models].

    Science.gov (United States)

    Scholte-Stalenhoef, A N; van den Bosch, R J

    2012-01-01

    Various theories have been proposed concerning the syndrome of Capgras. To search for a concept that is common to the various theories relating to the aetiology of the syndrome of Capgras. We begin by describing a new case of Capgras syndrome that we encountered recently, and thereafter we searched the literature using PubMed and PsycINFO. Various explanatory models converge in that they all assign a central role to a changed affect. A sensation of 'alienation' at a conscious or subconscious level, together with inadequate evaluation of beliefs, seems plausible. All models demonstrate some form of 'splitting' i.e. the separate processing of information in time, anatomy or mental representation. Although there is no conclusive evidence to support any one of the hypotheses, the models display striking similarities. They complement each other.

  7. Spherically-Convergent, Advanced-Fuel Systems

    Science.gov (United States)

    Barnes, D. C.; Nebel, R. A.; Schauer, M. M.; Umstadter, K. R.

    1998-11-01

    Combining nonneutral electron confinement with spherical ion convergence leads to a cm sized reactor volume with high power density.(R. A. Nebel and D. C. Barnes, Fusion Technol.), to appear (1998); D. C. Barnes and R. A. Nebel, Phys. of Plasmas 5, 2498 (1998). This concept is being investigated experimentally,(D. C. Barnes, T. B. Mitchell, and M. M. Schauer, Phys. Plasmas) 4, 1745 (1997). and results will be reported. We argue that D-D operation of such a system offers all the advantages of aneutronic fusion cycles. In particular, no breeding or large tritium inventory is required, and material problems seem tractable based on previous LWR experience. In addition the extremely small unit size leads to a massively modular system which is easily maintained and repaired, suggesting a very high availability. It may also be possible to operate such a system with low or aneutronic fuels. Preliminary work in this direction will be presented.

  8. Reliability and Security - Convergence or Divergence

    Directory of Open Access Journals (Sweden)

    Emil BURTESCU

    2010-01-01

    Full Text Available Reliability, as every technical field, must adapt to the new demands imposed by reality. Started initially as a field designed to control and ensure the smooth functionality of an element or technical system, reliability has reached the stage where the discussion is about the reliability management, similar to the other top-level fields. Security has its own contribution to the reliability of a system; a reliable system is a system with reliable security. In order for a system to be reliable, that means clear and safe, all its components must be reliable. In the following pages we will talk about the two main facts - reliability and security - to determine both the convergence and the divergence points.

  9. Biomedical engineering frontier research and converging technologies

    CERN Document Server

    Jun, Ho-Wook; Shin, Jennifer; Lee, SangHoon

    2016-01-01

    This book provides readers with an integrative overview of the latest research and developments in the broad field of biomedical engineering. Each of the chapters offers a timely review written by leading biomedical engineers and aims at showing how the convergence of scientific and engineering fields with medicine has created a new basis for practically solving problems concerning human health, wellbeing and disease. While some of the latest frontiers of biomedicine, such as neuroscience and regenerative medicine, are becoming increasingly dependent on new ideas and tools from other disciplines, the paradigm shift caused by technological innovations in the fields of information science, nanotechnology, and robotics is opening new opportunities in healthcare, besides dramatically changing the ways we actually practice science. At the same time, a new generation of engineers, fluent in many different scientific “languages,” is creating entirely new fields of research that approach the “old” questions f...

  10. Convergent and Divergent Adaptations of Subterranean Rodents

    DEFF Research Database (Denmark)

    Fang, Xiaodong

    ) have evolved convergent and divergent traits in many of their morphological, physiological, and/or behavioral characteristics, which facilitate their adaptions to a similar underground burrowing life style. For example, all these three rodents show degenerate visual acuity and advanced sensory systems...... in the dark; they display remarkable tolerance to a living environment with an excess of carbon dioxide and ammonia, but lack of oxygen; they exhibit extraordinarily long lives, and keep a fantastic resistance to cancer and other aging-associated diseases. In this study, we reported the genomic......, coupled with the reported genetic information, will promote the utilization of subterranean animal models for biological and biomedical research in the fight against aging, cancer, stroke and other realted diseases....

  11. Mediamorphosis: Analyzing the Convergence of Digital Media ...

    African Journals Online (AJOL)

    The history of the evolution of media shows that the introduction of a new medium does not mean the end or death of an existing old medium. The continuing overall growth and expansion of the media industries during the last century supports this assertion. Will the emergence and development of digital media forms mean ...

  12. Convergence and Fluctuations of Regularized Tyler Estimators

    Science.gov (United States)

    Kammoun, Abla; Couillet, Romain; Pascal, Ferderic; Alouini, Mohamed-Slim

    2016-02-01

    This article studies the behavior of regularized Tyler estimators (RTEs) of scatter matrices. The key advantages of these estimators are twofold. First, they guarantee by construction a good conditioning of the estimate and second, being a derivative of robust Tyler estimators, they inherit their robustness properties, notably their resilience to the presence of outliers. Nevertheless, one major problem that poses the use of RTEs in practice is represented by the question of setting the regularization parameter $\\rho$. While a high value of $\\rho$ is likely to push all the eigenvalues away from zero, it comes at the cost of a larger bias with respect to the population covariance matrix. A deep understanding of the statistics of RTEs is essential to come up with appropriate choices for the regularization parameter. This is not an easy task and might be out of reach, unless one considers asymptotic regimes wherein the number of observations $n$ and/or their size $N$ increase together. First asymptotic results have recently been obtained under the assumption that $N$ and $n$ are large and commensurable. Interestingly, no results concerning the regime of $n$ going to infinity with $N$ fixed exist, even though the investigation of this assumption has usually predated the analysis of the most difficult $N$ and $n$ large case. This motivates our work. In particular, we prove in the present paper that the RTEs converge to a deterministic matrix when $n\\to\\infty$ with $N$ fixed, which is expressed as a function of the theoretical covariance matrix. We also derive the fluctuations of the RTEs around this deterministic matrix and establish that these fluctuations converge in distribution to a multivariate Gaussian distribution with zero mean and a covariance depending on the population covariance and the parameter $\\rho$.

  13. Convergence and fluctuations of Regularized Tyler estimators

    KAUST Repository

    Kammoun, Abla

    2015-10-26

    This article studies the behavior of regularized Tyler estimators (RTEs) of scatter matrices. The key advantages of these estimators are twofold. First, they guarantee by construction a good conditioning of the estimate and second, being a derivative of robust Tyler estimators, they inherit their robustness properties, notably their resilience to the presence of outliers. Nevertheless, one major problem that poses the use of RTEs in practice is represented by the question of setting the regularization parameter p. While a high value of p is likely to push all the eigenvalues away from zero, it comes at the cost of a larger bias with respect to the population covariance matrix. A deep understanding of the statistics of RTEs is essential to come up with appropriate choices for the regularization parameter. This is not an easy task and might be out of reach, unless one considers asymptotic regimes wherein the number of observations n and/or their size N increase together. First asymptotic results have recently been obtained under the assumption that N and n are large and commensurable. Interestingly, no results concerning the regime of n going to infinity with N fixed exist, even though the investigation of this assumption has usually predated the analysis of the most difficult N and n large case. This motivates our work. In particular, we prove in the present paper that the RTEs converge to a deterministic matrix when n → ∞ with N fixed, which is expressed as a function of the theoretical covariance matrix. We also derive the fluctuations of the RTEs around this deterministic matrix and establish that these fluctuations converge in distribution to a multivariate Gaussian distribution with zero mean and a covariance depending on the population covariance and the parameter.

  14. Converging cylindrical magnetohydrodynamic shock collapse onto a power-law-varying line current

    KAUST Repository

    Mostert, W.

    2016-03-16

    We investigate the convergence behaviour of a cylindrical, fast magnetohydrodynamic (MHD) shock wave in a neutrally ionized gas collapsing onto an axial line current that generates a power law in time, azimuthal magnetic field. The analysis is done within the framework of a modified version of ideal MHD for an inviscid, non-dissipative, neutrally ionized compressible gas. The time variation of the magnetic field is tuned such that it approaches zero at the instant that the shock reaches the axis. This configuration is motivated by the desire to produce a finite magnetic field at finite shock radius but a singular gas pressure and temperature at the instant of shock impact. Our main focus is on the variation with shock radius, as, of the shock Mach number and pressure behind the shock as a function of the magnetic field power-law exponent, where gives a constant-in-time line current. The flow problem is first formulated using an extension of geometrical shock dynamics (GSD) into the time domain to take account of the time-varying conditions ahead of the converging shock, coupled with appropriate shock-jump conditions for a fast, symmetric MHD shock. This provides a pair of ordinary differential equations describing both and the time evolution on the shock, as a function of, constrained by a collapse condition required to achieve tuned shock convergence. Asymptotic, analytical results for and are obtained over a range of for general, and for both small and large . In addition, numerical solutions of the GSD equations are performed over a large range of, for selected parameters using . The accuracy of the GSD model is verified for some cases using direct numerical solution of the full, radially symmetric MHD equations using a shock-capturing method. For the GSD solutions, it is found that the physical character of the shock convergence to the axis is a strong function of . For μ≤0.816, and both approach unity at shock impact owing to the dominance of the strong

  15. Genetics of flower development in Ranunculales - a new, basal eudicot model order for studying flower evolution

    National Research Council Canada - National Science Library

    Damerval, Catherine; Becker, Annette

    2017-01-01

    ... to the genetic architecture of flower morphology and its evolution. These questions concern either traits only found in members of the Ranunculales or traits that have convergently evolved in other large clades of flowering plants...

  16. - JAPAN/USA: (THE APPARENT) MIRACLE OF CONVERGENCE

    OpenAIRE

    Matilde Mas Ivars; Francisco José Goerlich Gisbert

    1998-01-01

    With reference to the Baumol/de Long controversy over the importance of the sample selection when verifying the convergence hypothesis, the paper concludes that the convergence results are conditioned by the joint consideration of the United States and Japan in the same country sample. The illustration of this result lays on the ó-convergence concept and uses the simple coefficient of variation as dispersion statistics. The database is the one provided by the OCDE regarding prices and estimat...

  17. Convergence theorems for inertial KM-type algorithms

    Science.gov (United States)

    Maingé, Paul-Emile

    2008-09-01

    This paper deals with the convergence analysis of a general fixed point method which unifies KM-type (Krasnoselskii-Mann) iteration and inertial type extrapolation. This strategy is intended to speed up the convergence of algorithms in signal processing and image reconstruction that can be formulated as KM iterations. The convergence theorems established in this new setting improve known ones and some applications are given regarding convex feasibility problems, subgradient methods, fixed point problems and monotone inclusions.

  18. THE PERSPECTIVE OF ROMANIA'S CONVERGENCE IN THE EUROPEAN UNION

    Directory of Open Access Journals (Sweden)

    DUŢĂ ALEXANDRU

    2017-11-01

    Full Text Available In the paper we intend to analyze how Romania fulfills the Maastricht criteria. As a basis of assessment, we have used the convergence reports from 2014 and 2016. Our conclusion is that while most of the convergence criteria are met by Romania, the target of 2019 is inoperable and the setting of another target must take into account, in addition to the convergence criteria and financial stability, also the structural competitiveness of the Romanian economy.

  19. Disparity and convergence: Chinese provincial government health expenditures.

    Directory of Open Access Journals (Sweden)

    Jay Pan

    Full Text Available The huge regional disparity in government health expenditures (GHE is a major policy concern in China. This paper addresses whether provincial GHE converges in China from 1997 to 2009 using the economic convergence framework based on neoclassical economic growth theory. Our empirical investigation provides compelling evidence of long-term convergence in provincial GHE within China, but not in short-term. Policy implications of these empirical results are discussed.

  20. Disparity and Convergence: Chinese Provincial Government Health Expenditures

    Science.gov (United States)

    Pan, Jay; Wang, Peng; Qin, Xuezheng; Zhang, Shufang

    2013-01-01

    The huge regional disparity in government health expenditures (GHE) is a major policy concern in China. This paper addresses whether provincial GHE converges in China from 1997 to 2009 using the economic convergence framework based on neoclassical economic growth theory. Our empirical investigation provides compelling evidence of long-term convergence in provincial GHE within China, but not in short-term. Policy implications of these empirical results are discussed. PMID:23977049

  1. Convergence angles of tooth preparations assessed on dies for full ...

    African Journals Online (AJOL)

    Subject: Dies of full crown and bridge retainers. Results: A majority (59%) of the tooth preparations were for single crowns and 41% were for bridge retainers. The mean convergence angle for all the dies was 24.0○ with a mean buccal-lingual convergence angle of 26.7 ○ +11.93SD and a mean mesio-distal convergence ...

  2. Cosmic Divergence, Weak Cosmic Convergence, and Fixed Points at Infinity

    OpenAIRE

    Ryu, Ernest K.

    2017-01-01

    To characterize the asymptotic behavior of fixed-point iterations of non-expansive operators with no fixed points, Bauschke et al. [Fixed Point Theory Appl. (2016)] recently studied cosmic convergence and conjectured that cosmic convergence always holds. This paper presents a cosmically divergent counter example, which disproves this conjecture. This paper also demonstrates, with a counter example, that cosmic convergence can be weak in infinite dimensions. Finally, this paper shows positive ...

  3. Hausdorff convergence and the limit shape of the unicorns

    OpenAIRE

    Krauskopf, Bernd; Kriete, Hartje

    1997-01-01

    We discuss the Hausdorff convergence of hyperbolic components in parameter space as a one-parameter family of transcendental functions is dynamically approximated by polynomials. This convergence is strongly suggested by computer experiments and is proved in a weaker form, which is illustrated with exponential, sine and cosine families. Furthermore, we consider the convergence of subhyperbolic components. Our result also applies to the antiholomorphic exponentials, which all...

  4. On multigrid convergence of local algorithms for intrinsic volumes

    DEFF Research Database (Denmark)

    Local digital algorithms based on n×⋯×n configuration counts are commonly used within science for estimating intrinsic volumes from binary images. This paper investigates multigrid convergence of such algorithms. It is shown that local algorithms for intrinsic volumes other than volume...... are not multigrid convergent on the class of convex polytopes. In fact, counter examples are plenty. Also on the class of r-regular sets, counter examples to multigrid convergence are constructed for the surface area and the integrated mean curvature. Finally, a multigrid convergent local algorithm in 2D...

  5. Fractal aspects and convergence of Newton`s method

    Energy Technology Data Exchange (ETDEWEB)

    Drexler, M. [Oxford Univ. Computing Lab. (United Kingdom)

    1996-12-31

    Newton`s Method is a widely established iterative algorithm for solving non-linear systems. Its appeal lies in its great simplicity, easy generalization to multiple dimensions and a quadratic local convergence rate. Despite these features, little is known about its global behavior. In this paper, we will explain a seemingly random global convergence pattern using fractal concepts and show that the behavior of the residual is entirely explicable. We will also establish quantitative results for the convergence rates. Knowing the mechanism of fractal generation, we present a stabilization to the orthodox Newton method that remedies the fractal behavior and improves convergence.

  6. Convergence of Convective-Diffusive Lattice Boltzmann Methods

    CERN Document Server

    Elton, B H; Levermore, C D; Elton, Bracy H.; Rodrigue, Garry H.

    1993-01-01

    Lattice Boltzmann methods are numerical schemes derived as a kinetic approximation of an underlying lattice gas. A numerical convergence theory for nonlinear convective-diffusive lattice Boltzmann methods is established. Convergence, consistency, and stability are defined through truncated Hilbert expansions. In this setting it is shown that consistency and stability imply convergence. Monotone lattice Boltzmann methods are defined and shown to be stable, hence convergent when consistent. Examples of diffusive and convective-diffusive lattice Boltzmann methods that are both consistent and monotone are presented.

  7. Secretory gene recruitments in vampire bat salivary adaptation and potential convergences with sanguivorous leeches

    Directory of Open Access Journals (Sweden)

    Caleb Dakotah Phillips

    2015-11-01

    Full Text Available Regulatory evolution is thought to be fundamental to adaptive evolution. However, the identification of specific regulatory changes responsible for adaptation are sparse. Bats of the family Phyllostomidae, owing to their unparalleled rate of ecological and morphological evolution, represent an ideal system to identify regulatory evolution of adaptive significance. Among ecological niche leaps observed in this family, the most dramatic is the evolution of obligate sanguivory by vampire bats, which due to their highly derived phenotype, the sporadic phylogenetic occurrence of blood-feeding, and the adaptive potential of salivary glands, has enabled the development of hypotheses about adaptive molecular phenotypes. Using comparative transcriptomics of vampire bat, outgroup insectivorous bats, and sanguivorous leeches we identify genes that have been convergently recruited as secretory products of salivary glands of vampire bats and leeches. Comparisons of vampire bat to lineages maintaining the primitive chiropteran condition of insectivory indicated gene recruitment of alternative splice variants, and 5’ exon evolution, as the mechanisms producing secretory expression in vampire bats, but not in the insectivorous bats Macrotus and Myotis. Biochemical functions of hypothesized recruited genes explain adaptive benefits to sanguivory by modulating host hemostasis and neural signaling. It is difficult to identify how complex phenotypic change and rapid ecological transition, such as that observed in vampire bats, evolved over a short evolutionary timescale. Results indicate that regulatory evolution controlling tissue-specific splicing patterns has been important to successful adaptation of this lineage. Future studies that leverage emerging long sequence-read technologies, increased sample sizes, and expression and sequence comparisons across other sanguivore lineages will further elucidate roles of alternative splicing and gene recruitment in the

  8. Strong convergence and convergence rates of approximating solutions for algebraic Riccati equations in Hilbert spaces

    Science.gov (United States)

    Ito, Kazufumi

    1987-01-01

    The linear quadratic optimal control problem on infinite time interval for linear time-invariant systems defined on Hilbert spaces is considered. The optimal control is given by a feedback form in terms of solution pi to the associated algebraic Riccati equation (ARE). A Ritz type approximation is used to obtain a sequence pi sup N of finite dimensional approximations of the solution to ARE. A sufficient condition that shows pi sup N converges strongly to pi is obtained. Under this condition, a formula is derived which can be used to obtain a rate of convergence of pi sup N to pi. The results of the Galerkin approximation is demonstrated and applied for parabolic systems and the averaging approximation for hereditary differential systems.

  9. Bird evolution: testing the Metaves clade with six new mitochondrial genomes

    OpenAIRE

    Phillips Matthew J; Kardailsky Olga; Bartosch-Härlid Anna; Trewick Steve A; Morgan-Richards Mary; McLenachan Patricia A; Penny David

    2008-01-01

    Abstract Background Evolutionary biologists are often misled by convergence of morphology and this has been common in the study of bird evolution. However, the use of molecular data sets have their own problems and phylogenies based on short DNA sequences have the potential to mislead us too. The relationships among clades and timing of the evolution of modern birds (Neoaves) has not yet been well resolved. Evidence of convergence of morphology remain controversial. With six new bird mitochon...

  10. Evolution of Linux operating system network

    Science.gov (United States)

    Xiao, Guanping; Zheng, Zheng; Wang, Haoqin

    2017-01-01

    Linux operating system (LOS) is a sophisticated man-made system and one of the most ubiquitous operating systems. However, there is little research on the structure and functionality evolution of LOS from the prospective of networks. In this paper, we investigate the evolution of the LOS network. 62 major releases of LOS ranging from versions 1.0 to 4.1 are modeled as directed networks in which functions are denoted by nodes and function calls are denoted by edges. It is found that the size of the LOS network grows almost linearly, while clustering coefficient monotonically decays. The degree distributions are almost the same: the out-degree follows an exponential distribution while both in-degree and undirected degree follow power-law distributions. We further explore the functionality evolution of the LOS network. It is observed that the evolution of functional modules is shown as a sequence of seven events (changes) succeeding each other, including continuing, growth, contraction, birth, splitting, death and merging events. By means of a statistical analysis of these events in the top 4 largest components (i.e., arch, drivers, fs and net), it is shown that continuing, growth and contraction events occupy more than 95% events. Our work exemplifies a better understanding and describing of the dynamics of LOS evolution.

  11. Sustained fixation induced changes in phoria and convergence peak velocity.

    Directory of Open Access Journals (Sweden)

    Eun H Kim

    Full Text Available PURPOSE: This study sought to investigate the influence of phoria adaptation on convergence peak velocity from responses located at different initial vergence positions. METHODS: Symmetrical 4° convergence step responses and near dissociated phoria (measured at 40 cm from the subject's midline were recorded from six subjects with normal binocular vision using an infrared limbus tracking system with a haploscope. Two different sustained fixations (1° and 16° convergent rotation along the subject's midline were used to study whether phoria had an influence on the peak velocity of convergence responses located at two initial vergence positions (1° or 'far' steps and 12° or 'near' steps. RESULTS: Phoria was significantly adapted after a sustained fixation task at near (16° and far (1° (p<0.002. A repeated measures ANOVA showed that convergence far steps were significantly faster than the near steps (p<0.03. When comparing convergence steps with the same initial vergence position, steps measured after near phoria adaptation were faster than responses after far adaptation (p<0.02. A regression analysis demonstrated that the change in phoria and the change in convergence peak velocity were significantly correlated for the far convergence steps (r = 0.97, p = 0.001. A weaker correlation was observed for the near convergence steps (r = 0.59, p = 0.20. CONCLUSION: As a result of sustained fixation, phoria was adapted and the peak velocity of the near and far convergence steps was modified. This study has clinical considerations since prisms, which evoke phoria adaptation, can be prescribed to help alleviate visual discomfort. Future investigations should include a systematic study of how prisms may influence convergence and divergence eye movements for those prescribed with prisms within their spectacles.

  12. Converging cylindrical shocks in ideal magnetohydrodynamics

    KAUST Repository

    Pullin, D. I.

    2014-09-01

    We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R = √μ0/p0 I/(2π) where I is the current, μ0 is the permeability, and p0 is the pressure ahead of the shock. For shocks initiated at r ≫ R, shock convergence is first accompanied by shock strengthening as for the strictly gas-dynamic implosion. The diverging magnetic field then

  13. Teaching Evolution

    Science.gov (United States)

    Bryner, Jeanna

    2005-01-01

    Eighty years after the famous 1925 Scopes "monkey trial," which tested a teacher's right to discuss the theory of evolution in the classroom, evolution--and its most recent counterview, called "intelligent design"--are in the headlines again, and just about everyone seems to have an opinion. This past July, President Bush weighed in, telling…

  14. Monoplacophoran mitochondrial genomes: convergent gene arrangements and little phylogenetic signal.

    Science.gov (United States)

    Stöger, I; Kocot, K M; Poustka, A J; Wilson, N G; Ivanov, D; Halanych, K M; Schrödl, M

    2016-12-16

    Although recent studies have greatly advanced understanding of deep molluscan phylogeny, placement of some taxa remains uncertain as different datasets support competing class-relationships. Traditionally, morphologists have placed Monoplacophora, a group of morphologically simple, limpet-like molluscs as sister group to all other conchiferans (shelled molluscs other than Polyplacophora), a grouping that is supported by the latest large-scale phylogenomic study that includes Laevipilina. However, molecular datasets dominated by nuclear ribosomal genes support Monoplacophora + Polyplacophora (Serialia). Here, we evaluate the potential of mitochondrial genome data for resolving placement of Monoplacophora. Two complete (Laevipilina antarctica and Vema ewingi) and one partial (Laevipilina hyalina) mitochondrial genomes were sequenced, assembled, and compared. All three genomes show a highly similar architecture including an unusually high number of non-coding regions. Comparison of monoplacophoran gene order shows a gene arrangement pattern not previously reported; there is an inversion of one large gene cluster. Our reanalyses of recently published polyplacophoran mitogenomes show, however, that this feature is also present in some chiton species. Maximum Likelihood and Bayesian Inference analyses of 13 mitochondrial protein-coding genes failed to robustly place Monoplacophora and hypothesis testing could not reject any of the evaluated placements of Monoplacophora. Under both serialian or aculiferan-conchiferan scenarios, the observed gene cluster inversion appears to be a convergent evolution of gene arrangements in molluscs. Our phylogenetic results are inconclusive and sensitive to taxon sampling. Aculifera (Polyplacophora + Aplacophora) and Conchifera were never recovered. However, some analyses recovered Serialia (Monoplacophora + Polyplacophora), Diasoma (Bivalvia + Scaphopoda) or Pleistomollusca (Bivalvia + Gastropoda). Although we could

  15. TOGETHER OR APART? STRUCTURAL FUNDS AND REAL CONVERGENCE IN THE NEW MEMBER STATES

    Directory of Open Access Journals (Sweden)

    Tatomir Cristina Flavia

    2012-12-01

    Full Text Available The objective of this study is to analyze the relationship between the structural funds provided by the European Union (EU and the real convergence of the New Member States that joined the EU in 2004. We also assess the effect of the crisis on this. According to the empirical studies in this area, the impact can be both negative and positive. Furthermore, in the latter case, the correlation is not very strong and depends on several factors. To meet the research objective, we have structured this paper into five parts. In the first part, we make a short presentation of the Cohesion policy and its evolution in time. In the second part, we explore the importance of the subject in the economic literature. In the third one, we explain the methodology used in this paper. We contribute to the literature by creating a Real Convergence Index (RCI and by assessing the evolution of this index and of the structural funds payments from 2004 until 2010 in five New Member States (Hungary, the Czech Republic, Poland, Slovakia and Slovenia. The fourth part describes the results obtained. The structural funds payments reached a maximum level in 2007 in all the countries, with the exception of Slovenia. After this point, they recorded decreasing levels, mainly because of the economic and financial crisis. Within this group of countries, Poland and Slovakia recorded an increase in RCI during 2009 and 2010, even though the amounts of payments started decreasing. The highest level of structural funds payments and the maximum level of RCI are not synchronized, with the exception of the Czech Republic. This could come as a result of the lagging effects of structural funds on the economic convergence. The fifth part of the paper summarizes the conclusions of our research. The analysis confirms the previous work in this field. Specifically, it does not provide us with a clear result regarding the relationship between the absorption of structural funds and the real

  16. Convergence of Corporate and Public Governance

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    Gérard Hirigoyen

    2013-06-01

    Full Text Available By analyzing the differences between the corporate and public governance, theoretical and empirical research seems to indicate that the two domains of governance are far too different to share any common aspect. However, in this particular research, it has been argued that public governance is an application of corporate governance. Thus, the research question entails the description and analysis of this possible convergence of the two. Extensive research from literature on corporate governance has been undertaken to establish a relationship between the boards process and the roles that acts as a framework to bridge the gap separating corporate governance from public governance. Corporate governance, at a global level, exists in the for-profit as well as nonprofit organizations. Thus, the definition of this concept needs to be viewed from “an innovative” eye, considering the relationship between the process of the board and roles as characteristic of the public organization and private ones. As the private as well as public organizations are an application of corporate governance, the difference between the two gets narrowed. For the purpose of this research, the case of the French hospitals’ board has been taken into consideration. The members of the public board have been considered for the board process to perform their roles.

  17. Convergent syntheses of LeX analogues

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    An Wang

    2010-02-01

    Full Text Available The synthesis of three Lex derivatives from one common protected trisaccharide is reported. These analogues will be used respectively for competitive binding experiments, conjugation to carrier proteins and immobilization on gold. An N-acetylglucosamine monosaccharide acceptor was first glycosylated at O-4 with a galactosyl imidate. This coupling was performed at 40 °C under excess of BF3·OEt2 activation and proceeded best if the acceptor carried a 6-chlorohexyl rather than a 6-azidohexyl aglycon. The 6-chlorohexyl disaccharide was then converted to an acceptor and submitted to fucosylation yielding the corresponding protected 6-chlorohexyl Lex trisaccharide. This protected trisaccharide was used as a precursor to the 6-azidohexyl, 6-acetylthiohexyl and 6-benzylthiohexyl trisaccharide analogues which were obtained in excellent yields (70–95%. In turn, we describe the deprotection of these intermediates in one single step using dissolving metal conditions. Under these conditions, the 6-chlorohexyl and 6-azidohexyl intermediates led respectively to the n-hexyl and 6-aminohexyl trisaccharide targets. Unexpectedly, the 6-acetylthiohexyl analogue underwent desulfurization and gave the n-hexyl glycoside product, whereas the 6-benzylthiohexyl analogue gave the desired disulfide trisaccharide dimer. This study constitutes a particularly efficient and convergent preparation of these three Lex analogues.

  18. FISCAL RULES AND FISCAL RESPONSIBILITY CONVERGENCE

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    Anca Florentina GAVRILUŢĂ (VATAMANU

    2017-06-01

    Full Text Available In the last decades, against the background experience of countries which have known consecutive periods of fiscal instability, place all more often the problem of consolidating public finances and establish a sustainable and stable fiscal policies that respect fiscal responsibility criteria. Government decisions have a role well determined in critical periods of the economy and their approach with the purpose of putting in practice, dictate the future of entire generations. A way to counteract negative effects of the crisis and of the various factors that affecting the economy, is undoubtedly the increase of domestic supply. But in business reform process, it is also necessary to take into account a good instrumentation of fiscal budgetary policy, imposing the need to provide particular attention to the mechanisms of public finances and the specific instruments (expenditure, budget, revenue, public debt. The aim of this paper is to show the degree of compliance with the principles of fiscal responsibility, emphasizing which is the degree of convergence on fiscal responsibility. The methodology used is qualitative, which concerns the analysis on the contents of a series key documents: Statute of fiscal rules in the EU member states 28, the origin of fiscal rules and corroboration with specific elements of the public administration system, all this documents, enabling to build a index which validates the hypothesis of this research.

  19. 5G: The Convergence of Wireless Communications.

    Science.gov (United States)

    Chávez-Santiago, Raúl; Szydełko, Michał; Kliks, Adrian; Foukalas, Fotis; Haddad, Yoram; Nolan, Keith E; Kelly, Mark Y; Masonta, Moshe T; Balasingham, Ilangko

    As the rollout of 4G mobile communication networks takes place, representatives of industry and academia have started to look into the technological developments toward the next generation (5G). Several research projects involving key international mobile network operators, infrastructure manufacturers, and academic institutions, have been launched recently to set the technological foundations of 5G. However, the architecture of future 5G systems, their performance, and mobile services to be provided have not been clearly defined. In this paper, we put forth the vision for 5G as the convergence of evolved versions of current cellular networks with other complementary radio access technologies. Therefore, 5G may not be a single radio access interface but rather a "network of networks". Evidently, the seamless integration of a variety of air interfaces, protocols, and frequency bands, requires paradigm shifts in the way networks cooperate and complement each other to deliver data rates of several Gigabits per second with end-to-end latency of a few milliseconds. We provide an overview of the key radio technologies that will play a key role in the realization of this vision for the next generation of mobile communication networks. We also introduce some of the research challenges that need to be addressed.

  20. Weak convergence and uniform normalization in infinitary rewriting

    DEFF Research Database (Denmark)

    Simonsen, Jakob Grue

    2010-01-01

    We study infinitary term rewriting systems containing finitely many rules. For these, we show that if a weakly convergent reduction is not strongly convergent, it contains a term that reduces to itself in one step (but the step itself need not be part of the reduction). Using this result, we prov...