Abundance, biting behaviour and parous rate of anopheline mosquito species in relation to malaria incidence in gold-mining areas of southern Venezuela.

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Moreno, J E; Rubio-Palis, Y; Páez, E; Pérez, E; Sánchez, V

2007-12-01

A longitudinal entomological and epidemiological study was conducted in five localities of southern Venezuela between January 1999 and April 2000 to determine the abundance, biting behaviour and parity of anopheline mosquitoes (Diptera: Culicidae) in relation to climate variables and malaria incidence. A total of 3685 female anopheline mosquitoes, representing six species, were collected. The most abundant species were Anopheles marajoara Galvão & Damasceno (60.7%) and Anopheles darlingi Root (35.1%), which together represented 95.8% of the total anophelines collected. Abundance and species distribution varied by locality. Malaria prevalence varied from 12.5 to 21.4 cases per 1000 population. Transmission occurred throughout the year; the annual parasite index (API) for the study period was 813.0 cases per 1000 population, with a range of 71.6-2492 per 1000 population, depending on locality. Plasmodium vivax (Grassi & Feletti) (Coccidia: Plasmodiidae) accounted for 78.6% of cases, Plasmodium falciparum (Welch) for 21.4% and mixed infections (Pv+Pf) for 0.05) between mosquito abundance and rainfall. Correlations between malaria incidence by parasite species and mosquito abundance were not significant (P > 0.05). Monthly parous rates were similar for An. marajoara and An. darlingi throughout the year, with two peaks that coincided with the dry-rainy transition period and the period of less rain. Peaks in the incidence of malaria cases were observed 1 month after major peaks in biting rates of parous anophelines. Anopheles darlingi engages in biting activity throughout the night, with two minor peaks at 23.00-00.00 hours and 03.00-04.00 hours. Anopheles marajoara has a different pattern, with a biting peak at 19.00-21.00 hours and 76.6% of biting occurring before midnight. Although both vectors bite indoors and outdoors, they showed a highly significant (P < 0.01) degree of exophagic behaviour. The present study constitutes the first effort to characterize the

[Phylogeny and divergence time estimation of Schizothoracinae fishes in Xinjiang].

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Ayelhan, Haysa; Guo, Yan; Meng, Wei; Yang, Tianyan; Ma, Yanwu

2014-10-01

Based on combined data of mitochondrial COI, ND4 and 16S RNA genes, molecular phylogeny of 4 genera, 10 species or subspecies of Schizothoracinae fishes distributed in Xinjiang were analyzed. The molecular clock was calibrated by divergence time of Cyprininae and geological segregation event between the upper Yellow River and Qinghai Lake. Divergence time of Schizothoracinae fishes was calculated, and its relationship with the major geological events and the climate changes in surrounding areas of Tarim Basin was discussed. The results showed that genus Aspiorhynchus did not form an independent clade, but clustered with Schizothorax biddulphi and S. irregularis. Kimura 2-parameter model was used to calculate the genetic distance of COI gene, the genetic distance between genus Aspiorhynchus and Schizothorax did not reach genus level, and Aspiorhynchus laticeps might be a specialized species of genus Schizothorax. Cluster analysis showed a different result with morphological classification method, and it did not support the subgenus division of Schizothorax fishes. Divergence of two groups of primitive Schizothoracinae (8.18Ma) and divergence of Gymnodiptychus dybowskii and Diptychus maculates (7.67Ma) occurred in late Miocene, which might be related with the separation of Kunlun Mountain and north Tianshan Mountain River system that was caused by the uplift of Qinghai-Tibet Plateau and Tianshan Mountain, and the aridification of Tarim Basin. The terrain of Tarim Basin that was affected by Quaternary Himalayan movement was high in west but low in east, as a result, Lop Nor became the center of surrounding mountain rivers in Tarim Basin, which shaped the distribution pattern of genus Schizothorax.

The influence of the area of the Serra da Mesa Hydroelectric Plant, State of Goiás, on the frequency and diversity of anophelines (Diptera: Culicidae): a study on the effect of a reservoir.

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Melandri, Vanessa; Alencar, Jerônimo; Guimarães, Anthony Érico

2015-01-01

Bioecological aspects of anophelines (Diptera: Culicidae) near areas under the direct influence of the hydroelectric plant reservoir of Serra da Mesa in Goiás, Brazil, were analyzed. Samples were collected at the surrounding dam area during the phases before and after reservoir impoundment. The influence of climatic and environmental factors on the occurrence of Anopheles darlingi, Anopheles albitarsis, Anopheles triannulatus, Anopheles oswaldoi and Anopheles evansae was assessed using Pearson's correlations with indicators for richness and diversity as well as the index of species abundance (ISA) and the standardized index of species abundance (SISA). The highest anopheline density occurred during the phase after filling the tank; however, no direct correlation with the climatic factors was observed during this stage. The reservoir formation determined the incidence of the anopheline species. An. darlingi was the predominant species (SISA = 1.00). The significant difference (p < 0.05) observed between the species incidence during the different reservoir phases demonstrates the environmental effect of the reservoir on anophelines.

Prevalence and distribution of anopheline mosquitoes in malaria endemic areas of Asir region, Saudi Arabia.

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Abdoon, A M M O; Alshahrani, A M

2003-05-01

To study the prevalence of anopheline mosquitoes, over 180 sites were sampled in malaria-endemic areas of Asir region, Saudi Arabia, during June 1999-April 2001. A total of 7085 larval and 754 adult female Anopheles spp. specimens were collected. Seven species were identified: An. dthali, An. rupicolus, An. sergentii, An. arabiensis, An. multicolor, An. turkhudi and An. pretoriensis. Both An. arabiensis and An. sergentii are known vectors of malaria in the region. An. dthali occurred in all sites and was the most abundant species. An. turkhudi was collected in low numbers as larvae only. An. multicolor and An. pretoriensis were recorded for the first time in Asir region. An. sergentii is a species of the northern areas of the region, whereas An. arabiensis was more prevalent in the south.

Fossils, molecules, divergence times, and the origin of lissamphibians.

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Marjanović, David; Laurin, Michel

2007-06-01

A review of the paleontological literature shows that the early dates of appearance of Lissamphibia recently inferred from molecular data do not favor an origin of extant amphibians from temnospondyls, contrary to recent claims. A supertree is assembled using new Mesquite modules that allow extinct taxa to be incorporated into a time-calibrated phylogeny with a user-defined geological time scale. The supertree incorporates 223 extinct species of lissamphibians and has a highly significant stratigraphic fit. Some divergences can even be dated with sufficient precision to serve as calibration points in molecular divergence date analyses. Fourteen combinations of minimal branch length settings and 10 random resolutions for each polytomy give much more recent minimal origination times of lissamphibian taxa than recent studies based on a phylogenetic analyses of molecular sequences. Attempts to replicate recent molecular date estimates show that these estimates depend strongly on the choice of calibration points, on the dating method, and on the chosen model of evolution; for instance, the estimate for the date of the origin of Lissamphibia can lie between 351 and 266 Mya. This range of values is generally compatible with our time-calibrated supertree and indicates that there is no unbridgeable gap between dates obtained using the fossil record and those using molecular evidence, contrary to previous suggestions.

Metagenomics, paratransgenesis and the Anopheles microbiome: a portrait of the geographical distribution of the anopheline microbiota based on a meta-analysis of reported taxa.

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Villegas, Luis Martínez; Pimenta, Paulo Filemon Paolucci

2014-08-01

Anophelines harbour a diverse microbial consortium that may represent an extended gene pool for the host. The proposed effects of the insect microbiota span physiological, metabolic and immune processes. Here we synthesise how current metagenomic tools combined with classical culture-dependent techniques provide new insights in the elucidation of the role of the Anopheles-associated microbiota. Many proposed malaria control strategies have been based upon the immunomodulating effects that the bacterial components of the microbiota appear to exert and their ability to express anti-Plasmodium peptides. The number of identified bacterial taxa has increased in the current "omics" era and the available data are mostly scattered or in "tables" that are difficult to exploit. Published microbiota reports for multiple anopheline species were compiled in an Excel® spreadsheet. We then filtered the microbiota data using a continent-oriented criterion and generated a visual correlation showing the exclusive and shared bacterial genera among four continents. The data suggested the existence of a core group of bacteria associated in a stable manner with their anopheline hosts. However, the lack of data from Neotropical vectors may reduce the possibility of defining the core microbiota and understanding the mosquito-bacteria interactive consortium.

Use of geoprocessing to define malaria risk areas and evaluation of the vectorial importance of anopheline mosquitoes (Diptera: Culicidae) in Espírito Santo, Brazil.

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Meneguzzi, Viviane Coutinho; Santos, Claudiney Biral dos; Pinto, Israel de Souza; Feitoza, Leandro Roberto; Feitoza, Hideko Nagatani; Falqueto, Aloísio

2009-07-01

In Brazil, introduced malaria occurs from the flat to the sloping hot areas, predominantly outside the Amazon Region, where endemic malaria has occurred in the past. This is a consequence of human migrations to other Brazilian states, including the state of Espírito Santo (ES). The objective of this study was to use geoprocessing to define the areas at risk of introduced malaria transmission and evaluate the vectorial importance of species of anophelines in ES. Anophelines were sampled from 1997-2005 in 297 rural localities identified or not identified as foci of malaria during the last 20 years. The geoclimatic variables temperature, relief and marine influence were obtained from a database of the ES Natural Units. The 14,663 anophelines captured belonged to 22 species. A significant association was found between the occurrence of malaria foci and the presence of hot, low-lying areas or gently undulating to undulating relief. The occurrence of the disease was associated with the presence of Anopheles darlingi and Anopheles aquasalis. Geoprocessing was determined to be a useful tool for defining areas at risk for malaria and vectors in ES.

Environmental factors associated with larval habitats of anopheline mosquitoes (Diptera: Culicidae) in irrigation and major drainage areas in the middle course of the Rift Valley, central Ethiopia.

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Kenea, Oljira; Balkew, Meshesha; Gebre-Michael, Teshome

2011-06-01

Larval control is an integral part of malaria vector management in Ethiopia and elsewhere. For effective larval control, a sound understanding of the factors responsible for spatio-temporal variation in larval production is essential. A study was thus conducted to characterize larval habitats of anopheline mosquitoes in irrigation and major drainage areas between Adami Tulu and Meki towns, in the middle course of the Ethiopian Rift Valley. Aquatic habitats were sampled for anopheline larvae and the associated environmental variables (water temperature, turbidity, water current, water pH and other variables) were measured, characterized and analyzed. Microscopic identification of the late instars (III and IV) of anopheline larvae collected throughout the study period yielded nearly 47.6% Anopheles pharoensis, 32.1% An. arabiensis, 17.1% An. squamosus and only 3.2% of other species (An. coustani and An. cinereus). Larvae of the local malaria vectors, An. arabiensis and An. pharoensis were most abundantly sampled from sand pools and natural swamps, respectively. Logistic regression analysis detected four best predictor variables associated with larval abundance of malaria vector species. Thus, relative abundance of An. arabiensis larvae was significantly and inversely associated with aquatic vegetation and water current, whereas the relative abundance of An. pharoensis larvae was significantly and positively associated with water temperature and the presence of algae in the water bodies. Dry season anopheline larval habitats such as riverine sand pools that are created and maintained by perennial water bodies and their associated water development projects need to be considered in vector control operations.

Empirical and Bayesian approaches to fossil-only divergence times: A study across three reptile clades.

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Turner, Alan H; Pritchard, Adam C; Matzke, Nicholas J

2017-01-01

Estimating divergence times on phylogenies is critical in paleontological and neontological studies. Chronostratigraphically-constrained fossils are the only direct evidence of absolute timing of species divergence. Strict temporal calibration of fossil-only phylogenies provides minimum divergence estimates, and various methods have been proposed to estimate divergences beyond these minimum values. We explore the utility of simultaneous estimation of tree topology and divergence times using BEAST tip-dating on datasets consisting only of fossils by using relaxed morphological clocks and birth-death tree priors that include serial sampling (BDSS) at a constant rate through time. We compare BEAST results to those from the traditional maximum parsimony (MP) and undated Bayesian inference (BI) methods. Three overlapping datasets were used that span 250 million years of archosauromorph evolution leading to crocodylians. The first dataset focuses on early Sauria (31 taxa, 240 chars.), the second on early Archosauria (76 taxa, 400 chars.) and the third on Crocodyliformes (101 taxa, 340 chars.). For each dataset three time-calibrated trees (timetrees) were calculated: a minimum-age timetree with node ages based on earliest occurrences in the fossil record; a 'smoothed' timetree using a range of time added to the root that is then averaged over zero-length internodes; and a tip-dated timetree. Comparisons within datasets show that the smoothed and tip-dated timetrees provide similar estimates. Only near the root node do BEAST estimates fall outside the smoothed timetree range. The BEAST model is not able to overcome limited sampling to correctly estimate divergences considerably older than sampled fossil occurrence dates. Conversely, the smoothed timetrees consistently provide node-ages far older than the strict dates or BEAST estimates for morphologically conservative sister-taxa when they sit on long ghost lineages. In this latter case, the relaxed-clock model appears to

Empirical and Bayesian approaches to fossil-only divergence times: A study across three reptile clades.

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Alan H Turner

Full Text Available Estimating divergence times on phylogenies is critical in paleontological and neontological studies. Chronostratigraphically-constrained fossils are the only direct evidence of absolute timing of species divergence. Strict temporal calibration of fossil-only phylogenies provides minimum divergence estimates, and various methods have been proposed to estimate divergences beyond these minimum values. We explore the utility of simultaneous estimation of tree topology and divergence times using BEAST tip-dating on datasets consisting only of fossils by using relaxed morphological clocks and birth-death tree priors that include serial sampling (BDSS at a constant rate through time. We compare BEAST results to those from the traditional maximum parsimony (MP and undated Bayesian inference (BI methods. Three overlapping datasets were used that span 250 million years of archosauromorph evolution leading to crocodylians. The first dataset focuses on early Sauria (31 taxa, 240 chars., the second on early Archosauria (76 taxa, 400 chars. and the third on Crocodyliformes (101 taxa, 340 chars.. For each dataset three time-calibrated trees (timetrees were calculated: a minimum-age timetree with node ages based on earliest occurrences in the fossil record; a 'smoothed' timetree using a range of time added to the root that is then averaged over zero-length internodes; and a tip-dated timetree. Comparisons within datasets show that the smoothed and tip-dated timetrees provide similar estimates. Only near the root node do BEAST estimates fall outside the smoothed timetree range. The BEAST model is not able to overcome limited sampling to correctly estimate divergences considerably older than sampled fossil occurrence dates. Conversely, the smoothed timetrees consistently provide node-ages far older than the strict dates or BEAST estimates for morphologically conservative sister-taxa when they sit on long ghost lineages. In this latter case, the relaxed

Divergence time estimates and the evolution of major lineages in the florideophyte red algae

Science.gov (United States)

Yang, Eun Chan; Boo, Sung Min; Bhattacharya, Debashish; Saunders, Gary W.; Knoll, Andrew H.; Fredericq, Suzanne; Graf, Louis; Yoon, Hwan Su

2016-01-01

The Florideophyceae is the most abundant and taxonomically diverse class of red algae (Rhodophyta). However, many aspects of the systematics and divergence times of the group remain unresolved. Using a seven-gene concatenated dataset (nuclear EF2, LSU and SSU rRNAs, mitochondrial cox1, and plastid rbcL, psaA and psbA genes), we generated a robust phylogeny of red algae to provide an evolutionary timeline for florideophyte diversification. Our relaxed molecular clock analysis suggests that the Florideophyceae diverged approximately 943 (817–1,049) million years ago (Ma). The major divergences in this class involved the emergence of Hildenbrandiophycidae [ca. 781 (681–879) Ma], Nemaliophycidae [ca. 661 (597–736) Ma], Corallinophycidae [ca. 579 (543–617) Ma], and the split of Ahnfeltiophycidae and Rhodymeniophycidae [ca. 508 (442–580) Ma]. Within these clades, extant diversity reflects largely Phanerozoic diversification. Divergences within Florideophyceae were accompanied by evolutionary changes in the carposporophyte stage, leading to a successful strategy for maximizing spore production from each fertilization event. Our research provides robust estimates for the divergence times of major lineages within the Florideophyceae. This timeline was used to interpret the emergence of key morphological innovations that characterize these multicellular red algae. PMID:26892537

Protein kinase C-dependent signaling controls the midgut epithelial barrier to malaria parasite infection in anopheline mosquitoes.

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Nazzy Pakpour

Full Text Available Anopheline mosquitoes are the primary vectors of parasites in the genus Plasmodium, the causative agents of malaria. Malaria parasites undergo a series of complex transformations upon ingestion by the mosquito host. During this process, the physical barrier of the midgut epithelium, along with innate immune defenses, functionally restrict parasite development. Although these defenses have been studied for some time, the regulatory factors that control them are poorly understood. The protein kinase C (PKC gene family consists of serine/threonine kinases that serve as central signaling molecules and regulators of a broad spectrum of cellular processes including epithelial barrier function and immunity. Indeed, PKCs are highly conserved, ranging from 7 isoforms in Drosophila to 16 isoforms in mammals, yet none have been identified in mosquitoes. Despite conservation of the PKC gene family and their potential as targets for transmission-blocking strategies for malaria, no direct connections between PKCs, the mosquito immune response or epithelial barrier integrity are known. Here, we identify and characterize six PKC gene family members--PKCδ, PKCε, PKCζ, PKD, PKN, and an indeterminate conventional PKC--in Anopheles gambiae and Anopheles stephensi. Sequence and phylogenetic analyses of the anopheline PKCs support most subfamily assignments. All six PKCs are expressed in the midgut epithelia of A. gambiae and A. stephensi post-blood feeding, indicating availability for signaling in a tissue that is critical for malaria parasite development. Although inhibition of PKC enzymatic activity decreased NF-κB-regulated anti-microbial peptide expression in mosquito cells in vitro, PKC inhibition had no effect on expression of a panel of immune genes in the midgut epithelium in vivo. PKC inhibition did, however, significantly increase midgut barrier integrity and decrease development of P. falciparum oocysts in A. stephensi, suggesting that PKC

[Current status of the knowledge on Moroccan anophelines (Diptera: Culicidae): systematic, geographical distribution and vectorial competence].

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Faraj, C; Ouahabi, S; Adlaoui, E; Elaouad, R

2010-10-01

This bibliographical study, based on published works, ministry of Health Reports, exploitation of the database relative to the entomological surveillance conducted in the framework of the National Malaria Control Program, as well as unpublished results obtained within the framework of the European project "Emerging disease in a changing European environment", summarizes and completes with new data current knowledge on the systematics, the distribution and the vectorial competence of moroccan anophelines. Copyright © 2010 Elsevier Masson SAS. All rights reserved.

Investigations on anopheline mosquitoes close to the nest sites of chimpanzees subject to malaria infection in Ugandan Highlands

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Krief Sabrina

2012-04-01

Full Text Available Abstract Background Malaria parasites (Plasmodium sp., including new species, have recently been discovered as low grade mixed infections in three wild chimpanzees (Pan troglodytes schweinfurthii sampled randomly in Kibale National Park, Uganda. This suggested a high prevalence of malaria infection in this community. The clinical course of malaria in chimpanzees and the species of the vectors that transmit their parasites are not known. The fact that these apes display a specific behaviour in which they consume plant parts of low nutritional value but that contain compounds with anti-malarial properties suggests that the apes health might be affected by the parasite. The avoidance of the night-biting anopheline mosquitoes is another potential behavioural adaptation that would lead to a decrease in the number of infectious bites and consequently malaria. Methods Mosquitoes were collected over two years using suction-light traps and yeast-generated CO2 traps at the nesting and the feeding sites of two chimpanzee communities in Kibale National Park. The species of the female Anopheles caught were then determined and the presence of Plasmodium was sought in these insects by PCR amplification. Results The mosquito catches yielded a total of 309 female Anopheles specimens, the only known vectors of malaria parasites of mammalians. These specimens belonged to 10 species, of which Anopheles implexus, Anopheles vinckei and Anopheles demeilloni dominated. Sensitive DNA amplification techniques failed to detect any Plasmodium-positive Anopheles specimens. Humidity and trap height influenced the Anopheles capture success, and there was a negative correlation between nest numbers and mosquito abundance. The anopheline mosquitoes were also less diverse and numerous in sites where chimpanzees were nesting as compared to those where they were feeding. Conclusions These observations suggest that the sites where chimpanzees build their nests every night might be

So many genes, so little time: A practical approach to divergence-time estimation in the genomic era.

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Smith, Stephen A; Brown, Joseph W; Walker, Joseph F

2018-01-01

Phylogenomic datasets have been successfully used to address questions involving evolutionary relationships, patterns of genome structure, signatures of selection, and gene and genome duplications. However, despite the recent explosion in genomic and transcriptomic data, the utility of these data sources for efficient divergence-time inference remains unexamined. Phylogenomic datasets pose two distinct problems for divergence-time estimation: (i) the volume of data makes inference of the entire dataset intractable, and (ii) the extent of underlying topological and rate heterogeneity across genes makes model mis-specification a real concern. "Gene shopping", wherein a phylogenomic dataset is winnowed to a set of genes with desirable properties, represents an alternative approach that holds promise in alleviating these issues. We implemented an approach for phylogenomic datasets (available in SortaDate) that filters genes by three criteria: (i) clock-likeness, (ii) reasonable tree length (i.e., discernible information content), and (iii) least topological conflict with a focal species tree (presumed to have already been inferred). Such a winnowing procedure ensures that errors associated with model (both clock and topology) mis-specification are minimized, therefore reducing error in divergence-time estimation. We demonstrated the efficacy of this approach through simulation and applied it to published animal (Aves, Diplopoda, and Hymenoptera) and plant (carnivorous Caryophyllales, broad Caryophyllales, and Vitales) phylogenomic datasets. By quantifying rate heterogeneity across both genes and lineages we found that every empirical dataset examined included genes with clock-like, or nearly clock-like, behavior. Moreover, many datasets had genes that were clock-like, exhibited reasonable evolutionary rates, and were mostly compatible with the species tree. We identified overlap in age estimates when analyzing these filtered genes under strict clock and uncorrelated

Inventory control in multi-echelon divergent systems with random lead times

NARCIS (Netherlands)

Heijden, van der M.C.; Diks, E.B.; Kok, de A.G.

1996-01-01

This paper deals with integral inventory control in multi-echelon divergent systems with stochastic lead times. The policy considered is an echelon stock, periodic review, order-up-to (R, S) policy. A computational method is derived to obtain the order-up-to level and the allocation fractions

Inventory control in multi-echelon divergent systems with random lead times

NARCIS (Netherlands)

van der Heijden, Matthijs C.; Diks, Erik; de Kok, Ton

1999-01-01

This paper deals with integral inventory control in multi-echelon divergent systems with stochastic lead times. The policy considered is an echelon stock, periodic review, order-up-to (R, S) policy. A computational method is derived to obtain the order-up-to level and the allocation fractions

When can stress facilitate divergence by altering time to flowering?

OpenAIRE

Jordan, Crispin Y.; Ally, Dilara; Hodgins, Kathryn A.

2015-01-01

Abstract Stressors and heterogeneity are ubiquitous features of natural environments, and theory suggests that when environmental qualities alter flowering schedules through phenotypic plasticity, assortative mating can result that promotes evolutionary divergence. Therefore, it is important to determine whether common ecological stressors induce similar changes in flowering time. We review previous studies to determine whether two important stressors, water restriction and herbivory, induce ...

Consequences of Secondary Calibrations on Divergence Time Estimates.

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John J Schenk

Full Text Available Secondary calibrations (calibrations based on the results of previous molecular dating studies are commonly applied in divergence time analyses in groups that lack fossil data; however, the consequences of applying secondary calibrations in a relaxed-clock approach are not fully understood. I tested whether applying the posterior estimate from a primary study as a prior distribution in a secondary study results in consistent age and uncertainty estimates. I compared age estimates from simulations with 100 randomly replicated secondary trees. On average, the 95% credible intervals of node ages for secondary estimates were significantly younger and narrower than primary estimates. The primary and secondary age estimates were significantly different in 97% of the replicates after Bonferroni corrections. Greater error in magnitude was associated with deeper than shallower nodes, but the opposite was found when standardized by median node age, and a significant positive relationship was determined between the number of tips/age of secondary trees and the total amount of error. When two secondary calibrated nodes were analyzed, estimates remained significantly different, and although the minimum and median estimates were associated with less error, maximum age estimates and credible interval widths had greater error. The shape of the prior also influenced error, in which applying a normal, rather than uniform, prior distribution resulted in greater error. Secondary calibrations, in summary, lead to a false impression of precision and the distribution of age estimates shift away from those that would be inferred by the primary analysis. These results suggest that secondary calibrations should not be applied as the only source of calibration in divergence time analyses that test time-dependent hypotheses until the additional error associated with secondary calibrations is more properly modeled to take into account increased uncertainty in age estimates.

Observations on the distribution of anophelines in Suriname with particular reference to the malaria vector Anopheles darlingi

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J. A. Rozendaal

1990-06-01

Full Text Available A study was made on the distribution of anophelines in Suriname with special emphasis on the principal malaria vector Anopheles darlingi and on the occurrence of other possible vector species. Peridomestic human bait collections of adult mosquitoes and collections of larvae were made in many localities with a recent history of malaria transmission. Stable population of An. darlingi were only found in the interior, south of the limit of tidal influence, due to year-round availability of breeding habitats in quietly sunlit places in flooded forest areas and along river banks. In the area with tidal movement of the rivers, breeding is limited to flooded areas in the west season. Anopheles darlingi was only incidentally collected in low densities. In the interior, malaria transmission occurred in all places where An. darlingi was found. The absence of malaria transmission along the Upper Suriname River could be explained by the absence of An. darlingi. In the malaria endemic areas, An darlingi was the most numerous mosquito biting on man. In the tidal region, malaria outbreak are infrequent and might be explained by the temporary availability of favourable beeding habitats for An. darlingi. However, evidence is insufficient to incriminate an. darlingi as the vector of malaria in this region and the possible vectorial role of other anophelines is discussed.

Anopheline (Diptera:Culicidae) breeding in a traditional tank-based village ecosystem in north central Sri Lanka

DEFF Research Database (Denmark)

Amerasinghe, F P; Konradsen, F; Fonseka, K T

1997-01-01

A 13-mo survey of immature anopheline mosquitoes breeding in surface water habitats was done at Mahameegaswewa village within the Huruluwewa watershed in north central Sri Lanka as part of a multidisciplinary study on malaria epidemiology. The watershed is representative of the ancient small tank......-based irrigation network that still forms an important component of the rice production system in the low elevation dry zone. In total, 3,818 immatures representing 12 species were obtained from 2,940 samples taken from 5 larval habitats within the village ecosystem. Anopheles varuna Iyengar and An. culicifacies...

The Past Sure is Tense: On Interpreting Phylogenetic Divergence Time Estimates.

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Brown, Joseph W; Smith, Stephen A

2018-03-01

Divergence time estimation-the calibration of a phylogeny to geological time-is an integral first step in modeling the tempo of biological evolution (traits and lineages). However, despite increasingly sophisticated methods to infer divergence times from molecular genetic sequences, the estimated age of many nodes across the tree of life contrast significantly and consistently with timeframes conveyed by the fossil record. This is perhaps best exemplified by crown angiosperms, where molecular clock (Triassic) estimates predate the oldest (Early Cretaceous) undisputed angiosperm fossils by tens of millions of years or more. While the incompleteness of the fossil record is a common concern, issues of data limitation and model inadequacy are viable (if underexplored) alternative explanations. In this vein, Beaulieu et al. (2015) convincingly demonstrated how methods of divergence time inference can be misled by both (i) extreme state-dependent molecular substitution rate heterogeneity and (ii) biased sampling of representative major lineages. These results demonstrate the impact of (potentially common) model violations. Here, we suggest another potential challenge: that the configuration of the statistical inference problem (i.e., the parameters, their relationships, and associated priors) alone may preclude the reconstruction of the paleontological timeframe for the crown age of angiosperms. We demonstrate, through sampling from the joint prior (formed by combining the tree (diversification) prior with the calibration densities specified for fossil-calibrated nodes) that with no data present at all, that an Early Cretaceous crown angiosperms is rejected (i.e., has essentially zero probability). More worrisome, however, is that for the 24 nodes calibrated by fossils, almost all have indistinguishable marginal prior and posterior age distributions when employing routine lognormal fossil calibration priors. These results indicate that there is inadequate information in

Multiple insecticide resistance mechanisms involving metabolic changes and insensitive target sites selected in anopheline vectors of malaria in Sri Lanka

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Karunaratne SHP Parakrama

2008-08-01

Full Text Available Abstract Background The current status of insecticide resistance and the underlying resistance mechanisms were studied in the major vector of malaria, Anopheles culicifacies, and the secondary vector, Anopheles subpictus in five districts (Anuradhapura, Kurunegala, Moneragala, Puttalam and Trincomalee of Sri Lanka. Eight other anophelines, Anopheles annularis, Anopheles barbirostris, Anopheles jamesii, Anopheles nigerrimus, Anopheles peditaeniatus, Anopheles tessellatus, Anopheles vagus and Anopheles varuna from Anuradhapura district were also tested. Methods Adult females were exposed to the WHO discriminating dosages of DDT, malathion, fenitrothion, propoxur, λ-cyhalothrin, cyfluthrin, cypermethrin, deltamethrin, permethrin and etofenprox. The presence of metabolic resistance by esterase, glutathione S-transferase (GST and monooxygenase-based mechanisms, and the sensitivity of the acetylcholinesterase target site were assessed using synergists, and biochemical, and metabolic techniques. Results All the anopheline species had high DDT resistance. All An. culicifacies and An. subpictus populations were resistant to malathion, except An. culicifacies from Kurunegala, where there was no malathion carboxylesterase activity. Kurunegala and Puttalam populations of An. culicifacies were susceptible to fenitrothion. All the An. culicifacies populations were susceptible to carbamates. Both species were susceptible to the discriminating dosages of cypermethrin and cyfluthrin, but had different levels of resistance to other pyrethroids. Of the 8 other anophelines, only An. nigerrimus and An. peditaeniatus were resistant to all the insecticides tested, probably due to their high exposure to the insecticides used in agriculture. An. vagus showed some resistance to permethrin. Esterases, GSTs and monooxygenases were elevated in both An. culicifacies and An. subpictus. AChE was most sensitive to insecticides in Kurunegala and Trincomalee An. culicifacies

Probabilistic divergence time estimation without branch lengths: dating the origins of dinosaurs, avian flight and crown birds.

Science.gov (United States)

Lloyd, G T; Bapst, D W; Friedman, M; Davis, K E

2016-11-01

Branch lengths-measured in character changes-are an essential requirement of clock-based divergence estimation, regardless of whether the fossil calibrations used represent nodes or tips. However, a separate set of divergence time approaches are typically used to date palaeontological trees, which may lack such branch lengths. Among these methods, sophisticated probabilistic approaches have recently emerged, in contrast with simpler algorithms relying on minimum node ages. Here, using a novel phylogenetic hypothesis for Mesozoic dinosaurs, we apply two such approaches to estimate divergence times for: (i) Dinosauria, (ii) Avialae (the earliest birds) and (iii) Neornithes (crown birds). We find: (i) the plausibility of a Permian origin for dinosaurs to be dependent on whether Nyasasaurus is the oldest dinosaur, (ii) a Middle to Late Jurassic origin of avian flight regardless of whether Archaeopteryx or Aurornis is considered the first bird and (iii) a Late Cretaceous origin for Neornithes that is broadly congruent with other node- and tip-dating estimates. Demonstrating the feasibility of probabilistic time-scaling further opens up divergence estimation to the rich histories of extinct biodiversity in the fossil record, even in the absence of detailed character data. © 2016 The Authors.

Dusk to dawn activity patterns of anopheline mosquitoes in West Timor and Java, Indonesia.

Science.gov (United States)

Ndoen, Ermi; Wild, Clyde; Dale, Pat; Sipe, Neil; Dale, Mike

2011-05-01

Malaria is a serious health issue in Indonesia. We investigated the dusk to dawn anopheline mosquito activity patterns, host-seeking and resting locations in coastal plain, hilly and highland areas in West Timor and Java. Adult mosquitoes were captured landing on humans or resting in houses or animal barns. Data analyzed were: mosquito night-time activities; period of peak activity; night-time activity in specific periods of time and for mosquito resting locations. Eleven species were recorded; data were sparse for some species therefore detailed analyses were performed for four species only. In Java Anopheles vagus was common, with a bimodal pattern of high activity. In West Timor, its activity peaked around midnight. Other species with peak activity around the middle of the night were An. barbirostris and An. subpictus. Most species showed no biting and resting preference for indoors or outdoors, although An. barbirostris preferred indoors in West Timor, but outdoors in Java. An. aconitus and An. annularis preferred resting in human dwellings; An. subpictus and An. vagus preferred resting in animal barns. An. barbirostris preferred resting in human dwellings in West Timor and in animal barns in Java. The information is useful for planning the mosquito control aspect of malaria management. For example, where mosquito species have peak activity at night indoors, bednets and indoor residual spraying should reduce malaria risk, but where mosquitoes are most active outdoors, other options may be more effective.

Ancient divergence time estimates in Eutropis rugifera support the existence of Pleistocene barriers on the exposed Sunda Shelf

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Benjamin R. Karin

2017-10-01

Full Text Available Episodic sea level changes that repeatedly exposed and inundated the Sunda Shelf characterize the Pleistocene. Available evidence points to a more xeric central Sunda Shelf during periods of low sea levels, and despite the broad land connections that persisted during this time, some organisms are assumed to have faced barriers to dispersal between land-masses on the Sunda Shelf. Eutropis rugifera is a secretive, forest adapted scincid lizard that ranges across the Sunda Shelf. In this study, we sequenced one mitochondrial (ND2 and four nuclear (BRCA1, BRCA2, RAG1, and MC1R markers and generated a time-calibrated phylogeny in BEAST to test whether divergence times between Sundaic populations of E. rugifera occurred during Pleistocene sea-level changes, or if they predate the Pleistocene. We find that E. rugifera shows pre-Pleistocene divergences between populations on different Sundaic land-masses. The earliest divergence within E. rugifera separates the Philippine samples from the Sundaic samples approximately 16 Ma; the Philippine populations thus cannot be considered conspecific with Sundaic congeners. Sundaic populations diverged approximately 6 Ma, and populations within Borneo from Sabah and Sarawak separated approximately 4.5 Ma in the early Pliocene, followed by further cladogenesis in Sarawak through the Pleistocene. Divergence of peninsular Malaysian populations from the Mentawai Archipelago occurred approximately 5 Ma. Separation among island populations from the Mentawai Archipelago likely dates to the Pliocene/Pleistocene boundary approximately 3.5 Ma, and our samples from peninsular Malaysia appear to coalesce in the middle Pleistocene, about 1 Ma. Coupled with the monophyly of these populations, these divergence times suggest that despite consistent land-connections between these regions throughout the Pleistocene E. rugifera still faced barriers to dispersal, which may be a result of environmental shifts that accompanied the

First divergence time estimate of spiders, scorpions, mites and ticks (subphylum: Chelicerata) inferred from mitochondrial phylogeny.

Science.gov (United States)

Jeyaprakash, Ayyamperumal; Hoy, Marjorie A

2009-01-01

Spiders, scorpions, mites and ticks (chelicerates) form one of the most diverse groups of arthropods on land, but their origin and times of diversification are not yet established. We estimated, for the first time, the molecular divergence times for these chelicerates using complete mitochondrial sequences from 25 taxa. All mitochondrial genes were evaluated individually or after concatenation. Sequences belonging to three missing genes (ND3, 6, and tRNA-Asp) from three taxa, as well as the faster-evolving ribosomal RNAs (12S and 16S), tRNAs, and the third base of each codon from 11 protein-coding genes (PCGs) (COI-III, CYTB, ATP8, 6, ND1-2, 4L, and 4-5), were identified and removed. The remaining concatenated sequences from 11 PCGs produced a completely resolved phylogenetic tree and confirmed that all chelicerates are monophyletic. Removing the third base from each codon was essential to resolve the phylogeny, which allowed deep divergence times to be calculated using three nodes calibrated with upper and lower priors. Our estimates indicate that the orders and classes of spiders, scorpions, mites, and ticks diversified in the late Paleozoic, much earlier than previously reported from fossil date estimates. The divergence time estimated for ticks suggests that their first land hosts could have been amphibians rather than reptiles. Using molecular data, we separated the spider-scorpion clades and estimated their divergence times at 397 +/- 23 million years ago. Algae, fungi, plants, and animals, including insects, were well established on land when these chelicerates diversified. Future analyses, involving mitochondrial sequences from additional chelicerate taxa and the inclusion of nuclear genes (or entire genomes) will provide a more complete picture of the evolution of the Chelicerata, the second most abundant group of animals on earth.

Sugar and Multivitamin Diet Effects on The Longevity and Mating Capacity of Laboratory-Reared Male Anopheline Mosquitoes.

Science.gov (United States)

Phasomkusolsil, Siriporn; Pantuwatana, Kanchana; Tawong, Jaruwan; Khongtak, Weeraphan; Kertmanee, Yossasin; Monkanna, Nantaporn; Khaosanorh, Sakon; Wanja, Elizabeth W; Davidson, Silas A

2017-09-01

Successful mating by male mosquitoes is dependent on several factors, with sugar feeding being particularly important. The effect of ingested vitamins on adult male mosquitoes is poorly understood. This laboratory study used 3 anopheline species, Anopheles campestris, An. dirus, and An. sawadwongporni, to study the effect of sugar and vitamins on male longevity, copulation, and fecundity. Males were fed 1 of 5 diets containing different combinations of sugar and vitamins: 10% glucose, 10% sucrose, 10% multivitamin syrup, 10% multivitamin syrup + 10% glucose, and 10% multivitamin syrup + 10% sucrose. The longevity of males was measured for a period of 15 days. Forced mating was used to simulate copulation, and fecundity was measured by counting the number of eggs oviposited and the hatch rate of larvae. The longevity of An. campestris and An. dirus was greatest when fed a diet of 10% multivitamin syrup + 10% glucose, and the longevity of An. sawadwongporni was greatest when fed a diet of 10% multivitamin syrup + 10% sucrose. The 1st mating routinely produced the most viable eggs when males were mated with several females. The diet of 10% multivitamin syrup + 10% sucrose produced numerically greater egg production and larval emergence for all 3 species, although this was not always statistically significant due to variability and small sample size. These results indicate that the addition of multivitamin syrup to sucrose may produce healthier and more fit male anophelines. This has potential implications for increasing insectary operations and improving the fitness of laboratory-reared male mosquitoes that will be released for mosquito and disease-pathogen control studies.

Investigations of the Anopheline (Diptera: Culicidae fauna from three areas belonging to the Danube Delta Biosphere Reserve in order to evaluate the risk of malaria re-emergence

Directory of Open Access Journals (Sweden)

FALCUTA Elena

2008-10-01

Full Text Available The survey focused on the comparative analyses of the anopheline fauna belonging to the maculipennis group between three areas of the Danube Delta Biosphere Reserve, two of them situated near theRazim-Sinoe lagoonal complex and one belonging to the fluvial delta. The study that was carried out during 2006 and 2007 intended to establish the composition of the anopheline fauna as well as the longevity of the various species in order to evaluate the risk of malaria re-emergence. A number of 2437 mosquitoes, belonging to Anopheles maculipennis group were collected. The presence of the former vector species was pointed up: Anopheles atroparvus, Anophelesmesseae and Anopheles maculipennis sensu stricto. The investigations of the number of egg batches laid by a female have shown the physiological age of the respective female and namely if the female could infect or not the humans.

Relationships between anopheline mosquitoes and topography in West Timor and Java, Indonesia.

Science.gov (United States)

Ndoen, Ermi; Wild, Clyde; Dale, Pat; Sipe, Neil; Dale, Mike

2010-08-26

Malaria is a serious health issue in Indonesia. Mosquito control is one aspect of an integrated malaria management programme. To focus resources on priority areas, information is needed about the vectors and their habitats. This research aimed to identify the relationship between anopheline mosquitoes and topography in West Timor and Java. Study areas were selected in three topographic types in West Timor and Java. These were: coastal plain, hilly (rice field) and highland. Adult mosquitoes were captured landing on humans identified to species level and counted. Eleven species were recorded, four of which were significant for malaria transmission: Anopheles aconitus, Anopheles barbirostris, Anopheles subpictus and Anopheles sundaicus. Each species occupied different topographies, but only five were significantly associated: Anopheles annularis, Anopheles vagus and Anopheles subpictus (Java only) with hilly rice fields; Anopheles barbirostris, Anopheles maculatus and Anopheles subpictus (West Timor only) with coastal areas. Information on significant malaria vectors associated with specific topography is useful for planning the mosquito control aspect of malaria management.

Non-monotonicity and divergent time scale in Axelrod model dynamics

Science.gov (United States)

Vazquez, F.; Redner, S.

2007-04-01

We study the evolution of the Axelrod model for cultural diversity, a prototypical non-equilibrium process that exhibits rich dynamics and a dynamic phase transition between diversity and an inactive state. We consider a simple version of the model in which each individual possesses two features that can assume q possibilities. Within a mean-field description in which each individual has just a few interaction partners, we find a phase transition at a critical value qc between an active, diverse state for q < qc and a frozen state. For q lesssim qc, the density of active links is non-monotonic in time and the asymptotic approach to the steady state is controlled by a time scale that diverges as (q-qc)-1/2.

High annual and seasonal variations in malaria transmission by anophelines and vector species composition in Dielmo, a holoendemic area in Senegal

OpenAIRE

Fontenille, Didier; Lochouarn, Laurence; Diagne, N.; Sokhna, Cheik Sadibou; Lemasson, Jean-Jacques; Diatta, Mathurin; Konaté, L.; Faye, Faye; Rogier, C.; Trape, Jean-François

1997-01-01

We conducted a three-year entomologic study in Dielmo, a village of 250 inhabitants in a holoendemic area for malaria in Senegal. Anophelines were captured on human bait and by pyrethrum spray collections. The mosquitoes belonging to the #Anopheles gambiae$ complex were identified using the polymerase chain reaction. Malaria vectors captured were #An. funestus$, #An. arabiensis$, and #An. gambiae$. #An. funestus$ was the most abundant mosquito captured the first year, #An. arabiensis$ in the ...

Phylogenetic diversification patterns and divergence times in ground beetles (Coleoptera: Carabidae: Harpalinae).

Science.gov (United States)

Ober, Karen A; Heider, Thomas N

2010-08-27

Harpalinae is a species rich clade of carabid beetles with many unusual morphological forms and ecological interactions. How this diversity evolved has been difficult to reconstruct, perhaps because harpalines underwent a rapid burst of diversification early in their evolutionary history. Here we investigate the tempo of evolution in harpalines using molecular divergence dating techniques and explore the rates of lineage accumulation in harpalines and their sister group. According to molecular divergence date estimates, harpalines originated in the mid Cretaceous but did not diversify extensively until the late Cretaceous or early Paleogene about 32 million years after their origin. In a relatively small window of time, harpalines underwent rapid speciation. Harpalines have a relative high net diversification rate and increased cladogenesis in some regions of the clade. We did not see a significant decrease in diversification rate through time in the MCCR test, but a model of diversification with two shift points to lower diversification rates fit the harpaline lineage accumulation through time the best. Our results indicate harpalines are significantly more diverse and have higher diversification than their sistergroup. Instead of an immediate burst of explosive diversification, harpalines may have had a long "fuse" before major lineages diversified during the early Paleogene when other taxa such as mammals, birds, and some flowering plants were also rapidly diversifying.

Phylogenetic diversification patterns and divergence times in ground beetles (Coleoptera: Carabidae: Harpalinae

Directory of Open Access Journals (Sweden)

Ober Karen A

2010-08-01

Full Text Available Abstract Background Harpalinae is a species rich clade of carabid beetles with many unusual morphological forms and ecological interactions. How this diversity evolved has been difficult to reconstruct, perhaps because harpalines underwent a rapid burst of diversification early in their evolutionary history. Here we investigate the tempo of evolution in harpalines using molecular divergence dating techniques and explore the rates of lineage accumulation in harpalines and their sister group. Results According to molecular divergence date estimates, harpalines originated in the mid Cretaceous but did not diversify extensively until the late Cretaceous or early Paleogene about 32 million years after their origin. In a relatively small window of time, harpalines underwent rapid speciation. Harpalines have a relative high net diversification rate and increased cladogenesis in some regions of the clade. We did not see a significant decrease in diversification rate through time in the MCCR test, but a model of diversification with two shift points to lower diversification rates fit the harpaline lineage accumulation through time the best. Conclusions Our results indicate harpalines are significantly more diverse and have higher diversification than their sistergroup. Instead of an immediate burst of explosive diversification, harpalines may have had a long "fuse" before major lineages diversified during the early Paleogene when other taxa such as mammals, birds, and some flowering plants were also rapidly diversifying.

Finite Divergence

DEFF Research Database (Denmark)

Hansen, Michael Edberg; Pandya, P. K.; Chaochen, Zhou

1995-01-01

the framework of duration calculus. Axioms and proof rules are given. Patterns of occurrence of divergence are classified into dense divergence, accumulative divergence and discrete divergence by appropriate axioms. Induction rules are given for reasoning about discrete divergence...

Divergence times and colonization of the Canary Islands by Gallotia lizards.

Science.gov (United States)

Cox, Siobhan C; Carranza, Salvador; Brown, Richard P

2010-08-01

The Canary Islands have become a model region for evolutionary studies. We obtained 1.8 Kbp of mtDNA sequence from all known island forms of the endemic lizard genus Gallotia and from its sister taxon Psammodromus in order to reanalyze phylogenetic relationships within the archipelago, estimate lineage divergence times, and reconstruct the colonization history of this group. Well-supported phylogenies were obtained using maximum parsimony and Bayesian inference. Previous studies have been unable to establish the branching pattern at the base of the tree. We found evidence that G. stehlini (Gran Canaria) originated from the most basal Gallotia node and G. atlantica from the subsequent node. Divergence times were estimated under a global clock using Bayesian Markov Chain Monte Carlo methods implemented by three different programs: BEAST, MCMCTREE, MULTIDIVTIME. Node constraints were derived from subaerial island appearance data and were incorporated into the analyses as soft or hard maximal bounds. Posterior node ages differed slightly between programs, possibly due to different priors on divergence times. The most eastern Canary Islands first emerged just over 20 mya and their colonization appears to have taken place relatively quickly, around 17-20 mya. The subsequent node is consistent with cladogenesis due to colonization of Gran Canaria from the eastern islands about 11-13 mya. The western islands appear to have been colonized by a dispersal event from Lanzarote/Fuerteventura in the east to either La Gomera or one of the ancient edifices that subsequently formed Tenerife in the west, about 9-10 mya. Within the western islands, the most recent node that is ancestral to both the G. intermedia/G. gomerana/G. simonyi and the G.galloti/G. caesaris clades is dated at about 5-6 mya. Subsequent dispersal events between ancient Tenerife islands and La Gomera are dated at around 3 mya in both clades, although the direction of dispersal cannot be determined. Finally, we

Ultrasonic divergent-beam scanner for time-of-flight tomography with computer evaluation

Energy Technology Data Exchange (ETDEWEB)

Glover, G H

1978-03-02

The rotatable ultrasonic divergent-beam scanner is designed for time-of-flight tomography with computer evaluation. With it there can be measured parameters that are of importance for the structure of soft tissues, e.g. time as a function of the velocity distribution along a certain path of flight(the method is analogous to the transaxial X-ray tomography). Moreover it permits to perform the quantitative measurement of two-dimensional velocity distributions and may therefore be applied to serial examinations for detecting cancer of the breast. As computers digital memories as well as analog-digital-hybrid systems are suitable.

Local divergence and curvature divergence in first order optics

Science.gov (United States)

Mafusire, Cosmas; Krüger, Tjaart P. J.

2018-06-01

The far-field divergence of a light beam propagating through a first order optical system is presented as a square root of the sum of the squares of the local divergence and the curvature divergence. The local divergence is defined as the ratio of the beam parameter product to the beam width whilst the curvature divergence is a ratio of the space-angular moment also to the beam width. It is established that the beam’s focusing parameter can be defined as a ratio of the local divergence to the curvature divergence. The relationships between the two divergences and other second moment-based beam parameters are presented. Their various mathematical properties are presented such as their evolution through first order systems. The efficacy of the model in the analysis of high power continuous wave laser-based welding systems is briefly discussed.

Spatial variability in the density, distribution and vectorial capacity of anopheline species in a high transmission village (Equatorial Guinea

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Buatiche Jesús N

2006-03-01

Full Text Available Abstract Background Malaria transmission varies from one country to another and there are also local differences in time and space. An important variable when explaining the variability in transmission is the breeding behaviour of the different vector species and the availability of breeding sites. The aim of this study was to determine the geographical variability of certain entomological parameters: human biting rate (HBR, sporozoitic index (SI for Plasmodium falciparum and entomological inoculation rate (EIR. Methods The study was carried out in a small village in the mainland region of Equatorial Guinea. Adult mosquitoes were collected by CDC light traps. Polymerase Chain Reaction was employed to identify the species within the Anopheles gambiae complex and to detect P. falciparum sporozoites. The geographical position of all the dwellings in the village were taken using a global positioning system receiver unit. Data relating to the dwelling, occupants, use of bednets and the mosquitoes collection data were used to generate a geographical information system (GIS. This GIS allowed the minimum distance of the dwellings to the closest water point (potential breeding sites to be determined. Results A total of 1,173 anophelines were caught: 279 A. gambiae s.l. (217 A. gambiae s.s. and one Anopheles melas, 777 Anopheles moucheti and 117 Anopheles carnevalei. A. moucheti proved to be the main vector species and was responsible for 52.38 [95% IC: 33.7–71] night infective bites during this period. The highest SI was found in A. carnevalei (24%, even though the HBR was the lowest for this species. A significant association was found between the distance from the dwellings to the closest water point (River Ntem or secondary streams and the total HBR. Conclusion A clear association has been observed between the distance to potential breeding sites and the variability in the anopheline density, while the other parameters measured do not seem to

Anopheline larval habitats seasonality and species distribution: a prerequisite for effective targeted larval habitats control programmes.

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Eliningaya J Kweka

Full Text Available Larval control is of paramount importance in the reduction of malaria vector abundance and subsequent disease transmission reduction. Understanding larval habitat succession and its ecology in different land use managements and cropping systems can give an insight for effective larval source management practices. This study investigated larval habitat succession and ecological parameters which influence larval abundance in malaria epidemic prone areas of western Kenya.A total of 51 aquatic habitats positive for anopheline larvae were surveyed and visited once a week for a period of 85 weeks in succession. Habitats were selected and identified. Mosquito larval species, physico-chemical parameters, habitat size, grass cover, crop cycle and distance to nearest house were recorded. Polymerase chain reaction revealed that An. gambiae s.l was the most dominant vector species comprised of An.gambiae s.s (77.60% and An.arabiensis (18.34%, the remaining 4.06% had no amplification by polymerase chain reaction. Physico-chemical parameters and habitat size significantly influenced abundance of An. gambiae s.s (P = 0.024 and An. arabiensis (P = 0.002 larvae. Further, larval species abundance was influenced by crop cycle (P≤0.001, grass cover (P≤0.001, while distance to nearest houses significantly influenced the abundance of mosquito species larvae (r = 0.920;P≤0.001. The number of predator species influenced mosquito larval abundance in different habitat types. Crop weeding significantly influenced with the abundance of An.gambiae s.l (P≤0.001 when preceded with fertilizer application. Significantly higher anopheline larval abundance was recorded in habitats in pasture compared to farmland (P = 0.002. When habitat stability and habitat types were considered, hoof print were the most productive followed by disused goldmines.These findings suggest that implementation of effective larval control programme should be targeted with larval

Shape effects on time-scale divergence at athermal jamming transition of frictionless non-spherical particles

Science.gov (United States)

Yuan, Ye; Jin, Weiwei; Liu, Lufeng; Li, Shuixiang

2017-10-01

The critical behaviors of a granular system at the jamming transition have been extensively studied from both mechanical and thermodynamic perspectives. In this work, we numerically investigate the jamming behaviors of a variety of frictionless non-spherical particles, including spherocylinder, ellipsoid, spherotetrahedron and spherocube. In particular, for a given particle shape, a series of random configurations at different fixed densities are generated and relaxed to minimize interparticle overlaps using the relaxation algorithm. We find that as the jamming point (i.e., point J) is approached, the number of iteration steps (defined as the "time-scale" for our systems) required to completely relax the interparticle overlaps exhibits a clear power-law divergence. The dependence of the detailed mathematical form of the power-law divergence on particle shapes is systematically investigated and elucidated, which suggests that the shape effects can be generally categorized as elongation and roundness. Importantly, we show the jamming transition density can be accurately determined from the analysis of time-scale divergence for different non-spherical shapes, and the obtained values agree very well with corresponding ones reported in literature. Moreover, we study the plastic behaviors of over-jammed packings of different particles under a compression-expansion procedure and find that the jamming of ellipsoid is much more robust than other non-spherical particles. This work offers an alternative approximate procedure besides conventional packing algorithms for studying athermal jamming transition in granular system of frictionless non-spherical particles.

Impact of dams and irrigation schemes in Anopheline (Diptera: Culicidae bionomics and malaria epidemiology

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Jordi Sanchez-Ribas

2012-08-01

Full Text Available Irrigation schemes and dams have posed a great concern on public health systems of several countries, mainly in the tropics. The focus of the present review is to elucidate the different ways how these human interventions may have an effect on population dynamics of anopheline mosquitoes and hence, how local malaria transmission patterns may be changed. We discuss different studies within the three main tropical and sub-tropical regions (namely Africa, Asia and the Pacific and the Americas. Factors such as pre-human impact malaria epidemiological patterns, control measures, demographic movements, human behaviour and local Anopheles bionomics would determine if the implementation of an irrigation scheme or a dam will have negative effects on human health. Some examples of successful implementation of control measures in such settings are presented. The use of Geographic Information System as a powerful tool to assist on the study and control of malaria in these scenarios is also highlighted.

Divergence times in Caenorhabditis and Drosophila inferred from direct estimates of the neutral mutation rate.

Science.gov (United States)

Cutter, Asher D

2008-04-01

Accurate inference of the dates of common ancestry among species forms a central problem in understanding the evolutionary history of organisms. Molecular estimates of divergence time rely on the molecular evolutionary prediction that neutral mutations and substitutions occur at the same constant rate in genomes of related species. This underlies the notion of a molecular clock. Most implementations of this idea depend on paleontological calibration to infer dates of common ancestry, but taxa with poor fossil records must rely on external, potentially inappropriate, calibration with distantly related species. The classic biological models Caenorhabditis and Drosophila are examples of such problem taxa. Here, I illustrate internal calibration in these groups with direct estimates of the mutation rate from contemporary populations that are corrected for interfering effects of selection on the assumption of neutrality of substitutions. Divergence times are inferred among 6 species each of Caenorhabditis and Drosophila, based on thousands of orthologous groups of genes. I propose that the 2 closest known species of Caenorhabditis shared a common ancestor <24 MYA (Caenorhabditis briggsae and Caenorhabditis sp. 5) and that Caenorhabditis elegans diverged from its closest known relatives <30 MYA, assuming that these species pass through at least 6 generations per year; these estimates are much more recent than reported previously with molecular clock calibrations from non-nematode phyla. Dates inferred for the common ancestor of Drosophila melanogaster and Drosophila simulans are roughly concordant with previous studies. These revised dates have important implications for rates of genome evolution and the origin of self-fertilization in Caenorhabditis.

Divergence time estimates of mammals from molecular clocks and ...

Indian Academy of Sciences (India)

Prakash

2009-10-30

Oct 30, 2009 ... In the last decade and a half, mammalian phylogeny and lineage divergence .... not the sudden availability of ecological niches following the KTB mass .... fish fauna, ostracods, and palynofossils (Singh et al. 2006;. Prasad et al. ... tendons and hence the functional adaptations of the animal during its life and ...

The right time to happen: play developmental divergence in the two Pan species.

Directory of Open Access Journals (Sweden)

Elisabetta Palagi

Full Text Available Bonobos, compared to chimpanzees, are highly motivated to play as adults. Therefore, it is interesting to compare the two species at earlier developmental stages to determine how and when these differences arise. We measured and compared some play parameters between the two species including frequency, number of partners (solitary, dyadic, and polyadic play, session length, and escalation into overt aggression. Since solitary play has a role in developing cognitive and physical skills, it is not surprising that chimpanzees and bonobos share similar developmental trajectories in the motivation to engage in this activity. The striking divergence in play developmental pathways emerged for social play. Infants of the two species showed comparable social play levels, which began to diverge during the juvenile period, a 'timing hotspot' for play development. Compared to chimpanzees, social play sessions in juvenile bonobos escalated less frequently into overt aggression, lasted longer, and frequently involved more than two partners concurrently (polyadic play. In this view, play fighting in juvenile bonobos seems to maintain a cooperative mood, whereas in juvenile chimpanzees it acquires more competitive elements. The retention of juvenile traits into adulthood typical of bonobos can be due to a developmental delay in social inhibition. Our findings show that the divergence of play ontogenetic pathways between the two Pan species and the relative emergence of play neotenic traits in bonobos can be detected before individuals reach sexual maturity. The high play motivation showed by adult bonobos compared to chimpanzees is probably the result of a long developmental process, rooted in the delicate transitional phase, which leads subjects from infancy to juvenility.

Semantic search during divergent thinking.

Science.gov (United States)

Hass, Richard W

2017-09-01

Divergent thinking, as a method of examining creative cognition, has not been adequately analyzed in the context of modern cognitive theories. This article casts divergent thinking responding in the context of theories of memory search. First, it was argued that divergent thinking tasks are similar to semantic fluency tasks, but are more constrained, and less well structured. Next, response time distributions from 54 participants were analyzed for temporal and semantic clustering. Participants responded to two prompts from the alternative uses test: uses for a brick and uses for a bottle, for two minutes each. Participants' cumulative response curves were negatively accelerating, in line with theories of search of associative memory. However, results of analyses of semantic and temporal clustering suggested that clustering is less evident in alternative uses responding compared to semantic fluency tasks. This suggests either that divergent thinking responding does not involve an exhaustive search through a clustered memory trace, but rather that the process is more exploratory, yielding fewer overall responses that tend to drift away from close associates of the divergent thinking prompt. Copyright © 2017 Elsevier B.V. All rights reserved.

Adaptive divergence in flowering time among natural populations of Arabidopsis thaliana: Estimates of selection and QTL mapping.

Science.gov (United States)

Ågren, Jon; Oakley, Christopher G; Lundemo, Sverre; Schemske, Douglas W

2017-03-01

To identify the ecological and genetic mechanisms of local adaptation requires estimating selection on traits, identifying their genetic basis, and evaluating whether divergence in adaptive traits is due to conditional neutrality or genetic trade-offs. To this end, we conducted field experiments for three years using recombinant inbred lines (RILs) derived from two ecotypes of Arabidopsis thaliana (Italy, Sweden), and at each parental site examined selection on flowering time and mapped quantitative trait loci (QTL). There was strong selection for early flowering in Italy, but weak selection in Sweden. Eleven distinct flowering time QTL were detected, and for each the Italian genotype caused earlier flowering. Twenty-seven candidate genes were identified, two of which (FLC and VIN3) appear under major flowering time QTL in Italy. Seven of eight QTL in Italy with narrow credible intervals colocalized with previously reported fitness QTL, in comparison to three of four in Sweden. The results demonstrate that the magnitude of selection on flowering time differs strikingly between our study populations, that the genetic basis of flowering time variation is multigenic with some QTL of large effect, and suggest that divergence in flowering time between ecotypes is due mainly to conditional neutrality. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

Ion divergence in magnetically insulated diodes

International Nuclear Information System (INIS)

Slutz, S.A.; Lemke, R.W.; Pointon, T.D.; Desjarlais, M.P.; Johnson, D.J.; Mehlhorn, T.A.; Filuk, A.; Bailey, J.

1995-01-01

Magnetically insulated ion diodes are being developed to drive inertial confinement fusion. Ion beam microdivergence must be reduced to achieve the very high beam intensities required to achieve this goal. Three-dimensional particle-in-cell simulations indicate that instability induced fluctuations can produce significant ion divergence during acceleration. These simulations exhibit a fast growing mode early in time, which has been identified as the diocotron instability. The divergence generated by this mode is modest due to the relatively high frequency (>1GHz). Later, a low-frequency low-phase-velocity instability develops. This instability couples effectively to the ions, since the frequency is approximately the reciprocal of the ion transit time, and can generate unacceptably large ion divergences (>30 mrad). Linear stability theory reveals that this mode requires perturbations parallel to the applied magnetic field and is related to the modified two stream instability. Measurements of ion density fluctuations and energy-momentum correlations have confirmed that instabilities develop in ion diodes and contribute to the ion divergence. In addition, spectroscopic measurements indicate that the ions have a significant transverse temperature very close to the emission surface. Passive lithium fluoride (LiF) anodes have larger transverse beam temperatures than laser irradiated active sources. Calculations of source divergence expected from the roughness of LiF surfaces and the possible removal of this layer is presented

Resting behaviour of endophilic anopheline vectors in three ecological zones of southern Ghana and its implications for the use of entomopathogenic fungi

International Nuclear Information System (INIS)

Osae, M. Y.

2014-09-01

The aim of the study was to determine the resting behaviour and factors that influence the choice of resting sites by endophilic anopheline mosquitoes in southern Ghana. The study was carried out in six villages across three ecological zones of Southern Ghana, including: the forest ecological zone (FEZ), the coastal savannah ecological zone (CSEZ) and the forest-transition ecological zone (FTEZ). For every mosquito collected, the indoor resting sites was characterised and microclimate at the actual resting site recorded using a data logger. In the laboratory, full diagnostics was carried out on a sub-sample. Resting devices constructed from different materials were tested in a screen house and in village rooms. The dominant anopheline vectors include Anopheles gambiae s.s., An. coluzzii and An.funestus. An gambiae s.s. was the most dominant species in the villages from the FEZ and FTEZ, whereas An. coluzzii was most dominant in the CSEZ. An funestus was present in the FEZ and CSEZ but almost absent from the FTEZ. The two kdr mutations (L1014F and L1014S) were present in all the ecological zones and in both An. gambiae s.s. and An.coluzzii. This is the first report of the L1014S mutation from Ghana. The populations were highly anthropophagic and plasmodium falciparum was present in populations from all the villages studied. Woody materials appeared to be the most preferred resting materials for An. gambiae, accounting for 47% of all the resting sites for that species. They were also found on fabrics (26%), wall materials (12%), and roof materials (10%). Similarly, An. funestus preferred to rest on woody materials (58%), followed by wall materials (21%), fabrics (11%) and roofing materials (7%). For An.coluzzii, fabrics were the most preferred resting materials (38%) followed by roof materials (21%), wooden materials (19%) and wall materials (9%). All the three vector species preferred to rest higher up the room and closer to the walls, with large proportions of An

Kullback–Leibler quantum divergence as an indicator of quantum chaos

International Nuclear Information System (INIS)

Kowalewska-Kudłaszyk, A.; Kalaga, J.K.; Leoński, W.; Cao Long, V.

2012-01-01

We discuss a system of a nonlinear Kerr-like oscillator externally pumped by ultra-short, coherent pulses. For such a system, we analyse the application of the Kullback–Leibler quantum divergence K[ρ||σ] to the detection of quantum chaotic behaviour. Defining linear and nonlinear quantum divergences, and calculating their power spectra, we show that these parameters are more suitable indicators of quantum chaos than the fidelity commonly discussed in the literature, and are useful for dealing with short time series. Moreover, the nonlinear divergence is more sensitive to chaotic bands and to boundaries of chaotic regions, compared to its linear counterpart. -- Highlights: ► A nonlinear Kerr-like oscillator pumped by ultra-short coherent pulses is discussed. ► The Kullback–Leibler quantum divergence is analysed as an detector of quantum chaos. ► Linear and nonlinear quantum divergences and their power spectra are applied. ► The divergences are more adequate chaos's indicators than those based on fidelity. ► Defined nonlinear parameters are useful for dealing with short time series.

Phylogeny and Divergence Times of Lemurs Inferred with Recent and Ancient Fossils in the Tree.

Science.gov (United States)

Herrera, James P; Dávalos, Liliana M

2016-09-01

Paleontological and neontological systematics seek to answer evolutionary questions with different data sets. Phylogenies inferred for combined extant and extinct taxa provide novel insights into the evolutionary history of life. Primates have an extensive, diverse fossil record and molecular data for living and extinct taxa are rapidly becoming available. We used two models to infer the phylogeny and divergence times for living and fossil primates, the tip-dating (TD) and fossilized birth-death process (FBD). We collected new morphological data, especially on the living and extinct endemic lemurs of Madagascar. We combined the morphological data with published DNA sequences to infer near-complete (88% of lemurs) time-calibrated phylogenies. The results suggest that primates originated around the Cretaceous-Tertiary boundary, slightly earlier than indicated by the fossil record and later than previously inferred from molecular data alone. We infer novel relationships among extinct lemurs, and strong support for relationships that were previously unresolved. Dates inferred with TD were significantly older than those inferred with FBD, most likely related to an assumption of a uniform branching process in the TD compared with a birth-death process assumed in the FBD. This is the first study to combine morphological and DNA sequence data from extinct and extant primates to infer evolutionary relationships and divergence times, and our results shed new light on the tempo of lemur evolution and the efficacy of combined phylogenetic analyses. © The Author(s) 2016. Published by Oxford University Press, on behalf of the Society of Systematic Biologists. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Diverging Cohesion?

DEFF Research Database (Denmark)

Charron, Nicholas

2016-01-01

– which we define here as a combination of impartial bureaucratic practices, corruption and the rule of law – limits, and in some cases reverses the tendency towards greater divergence linked to trade. Countries with high levels of state capacity – that is, those that have greater government effectiveness......, stronger rule of law and lower corruption – experience lower levels of divergence, as they have the mechanisms to counterbalance the strong centripetal forces linked to openness. This claim is tested on countries that have experienced relatively high levels of increases in levels of economic and political......Why do increases in globalisation in the face of European expansion lead to sharp levels of regional divergences in wealth in some countries but not in others? The central crux of this paper is that convergence/divergence trends in European states are conditioned by ‘state capacity’. State capacity...

Phylogeny, time divergence, and historical biogeography of the South American Liolaemus alticolor-bibronii group (Iguania: Liolaemidae

Directory of Open Access Journals (Sweden)

Sabrina N. Portelli

2018-02-01

Full Text Available The genus Liolaemus comprises more than 260 species and can be divided in two subgenera: Eulaemus and Liolaemus sensu stricto. In this paper, we present a phylogenetic analysis, divergence times, and ancestral distribution ranges of the Liolaemus alticolor-bibronii group (Liolaemus sensu stricto subgenus. We inferred a total evidence phylogeny combining molecular (Cytb and 12S genes and morphological characters using Maximum Parsimony and Bayesian Inference. Divergence times were calculated using Bayesian MCMC with an uncorrelated lognormal distributed relaxed clock, calibrated with a fossil record. Ancestral ranges were estimated using the Dispersal-Extinction-Cladogenesis (DEC-Lagrange. Effects of some a priori parameters of DEC were also tested. Distribution ranged from central Perú to southern Argentina, including areas at sea level up to the high Andes. The L. alticolor-bibronii group was recovered as monophyletic, formed by two clades: L. walkeri and L. gracilis, the latter can be split in two groups. Additionally, many species candidates were recognized. We estimate that the L. alticolor-bibronii group diversified 14.5 Myr ago, during the Middle Miocene. Our results suggest that the ancestor of the Liolaemus alticolor-bibronii group was distributed in a wide area including Patagonia and Puna highlands. The speciation pattern follows the South-North Diversification Hypothesis, following the Andean uplift.

Divergent series and memory of the initial condition in the long-time solution of some anomalous diffusion problems.

Science.gov (United States)

Yuste, S Bravo; Borrego, R; Abad, E

2010-02-01

We consider various anomalous d -dimensional diffusion problems in the presence of an absorbing boundary with radial symmetry. The motion of particles is described by a fractional diffusion equation. Their mean-square displacement is given by r(2) proportional, variant t(gamma)(0divergent series appear when the concentration or survival probabilities are evaluated via the method of separation of variables. While the solution for normal diffusion problems is, at most, divergent as t-->0 , the emergence of such series in the long-time domain is a specific feature of subdiffusion problems. We present a method to regularize such series, and, in some cases, validate the procedure by using alternative techniques (Laplace transform method and numerical simulations). In the normal diffusion case, we find that the signature of the initial condition on the approach to the steady state rapidly fades away and the solution approaches a single (the main) decay mode in the long-time regime. In remarkable contrast, long-time memory of the initial condition is present in the subdiffusive case as the spatial part Psi1(r) describing the long-time decay of the solution to the steady state is determined by a weighted superposition of all spatial modes characteristic of the normal diffusion problem, the weight being dependent on the initial condition. Interestingly, Psi1(r) turns out to be independent of the anomalous diffusion exponent gamma .

Ecological characterisation and infection of Anophelines (Diptera: Culicidae) of the Atlantic Forest in the southeast of Brazil over a 10 year period: has the behaviour of the autochthonous malaria vector changed?

Science.gov (United States)

Buery, Julyana Cerqueira; Rezende, Helder Ricas; Natal, Licia; Silva, Leonardo Santana da; Menezes, Regiane Maria Tironi de; Fux, Blima; Malafronte, Rosely Dos Santos; Falqueto, Aloisio; Cerutti Junior, Crispim

2018-02-01

BACKGROUND In southeastern Brazil, autochthonous cases of malaria can be found near Atlantic Forest fragments. Because the transmission cycle has not been completely clarified, the behaviour of the possible vectors in those regions must be observed. A study concerning the entomological aspects and natural infection of anophelines (Diptera: Culicidae) captured in the municipalities of the mountainous region of Espírito Santo state was performed in 2004 and 2005. Similarly, between 2014 and 2015, 12 monthly collections were performed at the same area of the study mentioned above. METHODS Center for Disease Control (CDC) light traps with CO2 were set in open areas, at the edge and inside of the forest (canopy and ground), whereas Shannon traps were set on the edge. FINDINGS A total of 1,414 anophelines were collected from 13 species. Anopheles (Kerteszia) cruzii Dyar and Knab remained the most frequently captured species in the CDC traps set in the forest canopy, as well as being the vector with the highest prevalence of Plasmodium vivax/simium infection, according to molecular polymerase chain reaction techniques. CONCLUSIONS P. vivax/simium was found only in abdomens of the mosquitoes of the subgenus Nyssorhynchus, weakening the hypothesis that this subgenus also plays a role in malaria transmission in this specific region.

The emergence of lobsters: phylogenetic relationships, morphological evolution and divergence time comparisons of an ancient group (decapoda: achelata, astacidea, glypheidea, polychelida).

Science.gov (United States)

Bracken-Grissom, Heather D; Ahyong, Shane T; Wilkinson, Richard D; Feldmann, Rodney M; Schweitzer, Carrie E; Breinholt, Jesse W; Bendall, Matthew; Palero, Ferran; Chan, Tin-Yam; Felder, Darryl L; Robles, Rafael; Chu, Ka-Hou; Tsang, Ling-Ming; Kim, Dohyup; Martin, Joel W; Crandall, Keith A

2014-07-01

Lobsters are a ubiquitous and economically important group of decapod crustaceans that include the infraorders Polychelida, Glypheidea, Astacidea and Achelata. They include familiar forms such as the spiny, slipper, clawed lobsters and crayfish and unfamiliar forms such as the deep-sea and "living fossil" species. The high degree of morphological diversity among these infraorders has led to a dynamic classification and conflicting hypotheses of evolutionary relationships. In this study, we estimated phylogenetic relationships among the major groups of all lobster families and 94% of the genera using six genes (mitochondrial and nuclear) and 195 morphological characters across 173 species of lobsters for the most comprehensive sampling to date. Lobsters were recovered as a non-monophyletic assemblage in the combined (molecular + morphology) analysis. All families were monophyletic, with the exception of Cambaridae, and 7 of 79 genera were recovered as poly- or paraphyletic. A rich fossil history coupled with dense taxon coverage allowed us to estimate and compare divergence times and origins of major lineages using two drastically different approaches. Age priors were constructed and/or included based on fossil age information or fossil discovery, age, and extant species count data. Results from the two approaches were largely congruent across deep to shallow taxonomic divergences across major lineages. The origin of the first lobster-like decapod (Polychelida) was estimated in the Devonian (∼409-372 Ma) with all infraorders present in the Carboniferous (∼353-318 Ma). Fossil calibration subsampling studies examined the influence of sampling density (number of fossils) and placement (deep, middle, and shallow) on divergence time estimates. Results from our study suggest including at least 1 fossil per 10 operational taxonomic units (OTUs) in divergence dating analyses. [Dating; decapods; divergence; lobsters; molecular; morphology; phylogenetics.]. © The

Quantum skew divergence

Energy Technology Data Exchange (ETDEWEB)

Audenaert, Koenraad M. R., E-mail: koenraad.audenaert@rhul.ac.uk [Department of Mathematics, Royal Holloway University of London, Egham TW20 0EX, United Kingdom and Department of Physics and Astronomy, University of Ghent, S9, Krijgslaan 281, B-9000 Ghent (Belgium)

2014-11-15

In this paper, we study the quantum generalisation of the skew divergence, which is a dissimilarity measure between distributions introduced by Lee in the context of natural language processing. We provide an in-depth study of the quantum skew divergence, including its relation to other state distinguishability measures. Finally, we present a number of important applications: new continuity inequalities for the quantum Jensen-Shannon divergence and the Holevo information, and a new and short proof of Bravyi's Small Incremental Mixing conjecture.

On Hölder Projective Divergences

KAUST Repository

Nielsen, Frank

2017-03-16

We describe a framework to build distances by measuring the tightness of inequalities and introduce the notion of proper statistical divergences and improper pseudo-divergences. We then consider the Holder ordinary and reverse inequalities and present two novel classes of Holder divergences and pseudo-divergences that both encapsulate the special case of the Cauchy-Schwarz divergence. We report closed-form formulas for those statistical dissimilarities when considering distributions belonging to the same exponential family provided that the natural parameter space is a cone (e.g., multivariate Gaussians) or affine (e.g., categorical distributions). Those new classes of Holder distances are invariant to rescaling and thus do not require distributions to be normalized. Finally, we show how to compute statistical Holder centroids with respect to those divergences and carry out center-based clustering toy experiments on a set of Gaussian distributions which demonstrate empirically that symmetrized Holder divergences outperform the symmetric Cauchy-Schwarz divergence.

On Hölder Projective Divergences

KAUST Repository

Nielsen, Frank; Sun, Ke; Marchand-Maillet, Stephane

2017-01-01

We describe a framework to build distances by measuring the tightness of inequalities and introduce the notion of proper statistical divergences and improper pseudo-divergences. We then consider the Holder ordinary and reverse inequalities and present two novel classes of Holder divergences and pseudo-divergences that both encapsulate the special case of the Cauchy-Schwarz divergence. We report closed-form formulas for those statistical dissimilarities when considering distributions belonging to the same exponential family provided that the natural parameter space is a cone (e.g., multivariate Gaussians) or affine (e.g., categorical distributions). Those new classes of Holder distances are invariant to rescaling and thus do not require distributions to be normalized. Finally, we show how to compute statistical Holder centroids with respect to those divergences and carry out center-based clustering toy experiments on a set of Gaussian distributions which demonstrate empirically that symmetrized Holder divergences outperform the symmetric Cauchy-Schwarz divergence.

Creative Cognition in Secondary Science: An exploration of divergent thinking in science among adolescents

Science.gov (United States)

Antink-Meyer, Allison; Lederman, Norman G.

2015-07-01

The divergent thinking skills in science of 282 US high school students were investigated across 16 weeks of instruction in order to determine whether typical academic time periods can significantly influence changes in thinking skills. Students' from 6 high school science classrooms completed the Scientific Structures Creativity Measure (SSCM) before and after a semester of instruction. Even the short time frame of a typical academic term was found to be sufficient to promote both improvements in divergent thinking skills as well as declining divergent thinking. Declining divergent thinking skills were more common in this time frame than were improvements. The nature of student performance on the SSCM and implications are discussed.

String perturbation theory diverges

International Nuclear Information System (INIS)

Gross, D.J.; Periwal, V.

1988-01-01

We prove that perturbation theory for the bosonic string diverges for arbitrary values of the coupling constant and is not Borel summable. This divergence is independent of the existence of the infinities that occur in the theory due to the presence of tachyons and dilaton tadpoles. We discuss the physical implications of such a divergence

Detection of 1014F kdr mutation in four major Anopheline malaria vectors in Indonesia

Directory of Open Access Journals (Sweden)

Sukowati Supratman

2010-11-01

Full Text Available Abstract Background Malaria is a serious public health problem in Indonesia, particularly in areas outside Java and Bali. The spread of resistance to the currently available anti-malarial drugs or insecticides used for mosquito control would cause an increase in malaria transmission. To better understand patterns of transmission and resistance in Indonesia, an integrated mosquito survey was conducted in three areas with different malaria endemicities, Purworejo in Central Java, South Lampung District in Sumatera and South Halmahera District in North Mollucca. Methods Mosquitoes were collected from the three areas through indoor and outdoor human landing catches (HLC and indoor restinging catches. Specimens were identified morphologically by species and kept individually in 1.5 ml Eppendorf microtube. A fragment of the VGSC gene from 95 mosquito samples was sequenced and kdr allelic variation determined. Results The molecular analysis of these anopheline mosquitoes revealed the existence of the 1014F allele in 4 major malaria vectors from South Lampung. These species include, Anopheles sundaicus, Anopheles aconitus, Anopheles subpictus and Anopheles vagus. The 1014F allele was not found in the other areas. Conclusion The finding documents the presence of this mutant allele in Indonesia, and implies that selection pressure on the Anopheles population in this area has occurred. Further studies to determine the impact of the resistance allele on the efficacy of pyrethroids in control programmes are needed.

Detection of 1014F kdr mutation in four major Anopheline malaria vectors in Indonesia.

Science.gov (United States)

Syafruddin, Din; Hidayati, Anggi P N; Asih, Puji B S; Hawley, William A; Sukowati, Supratman; Lobo, Neil F

2010-11-08

Malaria is a serious public health problem in Indonesia, particularly in areas outside Java and Bali. The spread of resistance to the currently available anti-malarial drugs or insecticides used for mosquito control would cause an increase in malaria transmission. To better understand patterns of transmission and resistance in Indonesia, an integrated mosquito survey was conducted in three areas with different malaria endemicities, Purworejo in Central Java, South Lampung District in Sumatera and South Halmahera District in North Mollucca. Mosquitoes were collected from the three areas through indoor and outdoor human landing catches (HLC) and indoor restinging catches. Specimens were identified morphologically by species and kept individually in 1.5 ml Eppendorf microtube. A fragment of the VGSC gene from 95 mosquito samples was sequenced and kdr allelic variation determined. The molecular analysis of these anopheline mosquitoes revealed the existence of the 1014F allele in 4 major malaria vectors from South Lampung. These species include, Anopheles sundaicus, Anopheles aconitus, Anopheles subpictus and Anopheles vagus. The 1014F allele was not found in the other areas. The finding documents the presence of this mutant allele in Indonesia, and implies that selection pressure on the Anopheles population in this area has occurred. Further studies to determine the impact of the resistance allele on the efficacy of pyrethroids in control programmes are needed.

Divergent Cumulative Cultural Evolution

OpenAIRE

Marriott, Chris; Chebib, Jobran

2016-01-01

Divergent cumulative cultural evolution occurs when the cultural evolutionary trajectory diverges from the biological evolutionary trajectory. We consider the conditions under which divergent cumulative cultural evolution can occur. We hypothesize that two conditions are necessary. First that genetic and cultural information are stored separately in the agent. Second cultural information must be transferred horizontally between agents of different generations. We implement a model with these ...

Rates of genomic divergence in humans, chimpanzees and their lice.

Science.gov (United States)

Johnson, Kevin P; Allen, Julie M; Olds, Brett P; Mugisha, Lawrence; Reed, David L; Paige, Ken N; Pittendrigh, Barry R

2014-02-22

The rate of DNA mutation and divergence is highly variable across the tree of life. However, the reasons underlying this variation are not well understood. Comparing the rates of genetic changes between hosts and parasite lineages that diverged at the same time is one way to begin to understand differences in genetic mutation and substitution rates. Such studies have indicated that the rate of genetic divergence in parasites is often faster than that of their hosts when comparing single genes. However, the variation in this relative rate of molecular evolution across different genes in the genome is unknown. We compared the rate of DNA sequence divergence between humans, chimpanzees and their ectoparasitic lice for 1534 protein-coding genes across their genomes. The rate of DNA substitution in these orthologous genes was on average 14 times faster for lice than for humans and chimpanzees. In addition, these rates were positively correlated across genes. Because this correlation only occurred for substitutions that changed the amino acid, this pattern is probably produced by similar functional constraints across the same genes in humans, chimpanzees and their ectoparasites.

Multilocus phylogeny, divergence times, and a major role for the benthic-to-pelagic axis in the diversification of grunts (Haemulidae).

Science.gov (United States)

Tavera, Jose; Acero P, Arturo; Wainwright, Peter C

2018-04-01

We present a phylogenetic analysis with divergence time estimates, and an ecomorphological assessment of the role of the benthic-to-pelagic axis of diversification in the history of haemulid fishes. Phylogenetic analyses were performed on 97 grunt species based on sequence data collected from seven loci. Divergence time estimation indicates that Haemulidae originated during the mid Eocene (54.7-42.3 Ma) but that the major lineages were formed during the mid-Oligocene 30-25 Ma. We propose a new classification that reflects the phylogenetic history of grunts. Overall the pattern of morphological and functional diversification in grunts appears to be strongly linked with feeding ecology. Feeding traits and the first principal component of body shape strongly separate species that feed in benthic and pelagic habitats. The benthic-to-pelagic axis has been the major axis of ecomorphological diversification in this important group of tropical shoreline fishes, with about 13 transitions between feeding habitats that have had major consequences for head and body morphology. Copyright © 2017 Elsevier Inc. All rights reserved.

k-Means Clustering with Hölder Divergences

KAUST Repository

Nielsen, Frank

2017-10-24

We introduced two novel classes of Hölder divergences and Hölder pseudo-divergences that are both invariant to rescaling, and that both encapsulate the Cauchy-Schwarz divergence and the skew Bhattacharyya divergences. We review the elementary concepts of those parametric divergences, and perform a clustering analysis on two synthetic datasets. It is shown experimentally that the symmetrized Hölder divergences consistently outperform significantly the Cauchy-Schwarz divergence in clustering tasks.

k-Means Clustering with Hölder Divergences

KAUST Repository

Nielsen, Frank; Sun, Ke; Marchand-Maillet, Sté phane

2017-01-01

We introduced two novel classes of Hölder divergences and Hölder pseudo-divergences that are both invariant to rescaling, and that both encapsulate the Cauchy-Schwarz divergence and the skew Bhattacharyya divergences. We review the elementary concepts of those parametric divergences, and perform a clustering analysis on two synthetic datasets. It is shown experimentally that the symmetrized Hölder divergences consistently outperform significantly the Cauchy-Schwarz divergence in clustering tasks.

Hyperreal Numbers for Infinite Divergent Series

OpenAIRE

Bartlett, Jonathan

2018-01-01

Treating divergent series properly has been an ongoing issue in mathematics. However, many of the problems in divergent series stem from the fact that divergent series were discovered prior to having a number system which could handle them. The infinities that resulted from divergent series led to contradictions within the real number system, but these contradictions are largely alleviated with the hyperreal number system. Hyperreal numbers provide a framework for dealing with divergent serie...

The fossil record and taphonomy of butterflies and moths (Insecta, Lepidoptera): implications for evolutionary diversity and divergence-time estimates.

Science.gov (United States)

Sohn, Jae-Cheon; Labandeira, Conrad C; Davis, Donald R

2015-02-04

It is conventionally accepted that the lepidopteran fossil record is significantly incomplete when compared to the fossil records of other, very diverse, extant insect orders. Such an assumption, however, has been based on cumulative diversity data rather than using alternative statistical approaches from actual specimen counts. We reviewed documented specimens of the lepidopteran fossil record, currently consisting of 4,593 known specimens that are comprised of 4,262 body fossils and 331 trace fossils. The temporal distribution of the lepidopteran fossil record shows significant bias towards the late Paleocene to middle Eocene time interval. Lepidopteran fossils also record major shifts in preservational style and number of represented localities at the Mesozoic stage and Cenozoic epoch level of temporal resolution. Only 985 of the total known fossil specimens (21.4%) were assigned to 23 of the 40 extant lepidopteran superfamilies. Absolute numbers and proportions of preservation types for identified fossils varied significantly across superfamilies. The secular increase of lepidopteran family-level diversity through geologic time significantly deviates from the general pattern of other hyperdiverse, ordinal-level lineages. Our statistical analyses of the lepidopteran fossil record show extreme biases in preservation type, age, and taxonomic composition. We highlight the scarcity of identified lepidopteran fossils and provide a correspondence between the latest lepidopteran divergence-time estimates and relevant fossil occurrences at the superfamily level. These findings provide caution in interpreting the lepidopteran fossil record through the modeling of evolutionary diversification and in determination of divergence time estimates.

The divergence theorem for divergence measure vectorfields on sets with fractal boundaries

Czech Academy of Sciences Publication Activity Database

Šilhavý, Miroslav

2009-01-01

Roč. 14, č. 5 (2009), s. 445-455 ISSN 1081-2865 Institutional research plan: CEZ:AV0Z10190503 Keywords : divergence measure vectorfields * fractal s * divergence theorem Subject RIV: BA - General Mathematics Impact factor: 1.065, year: 2009

The Patchwork Divergence Theorem

OpenAIRE

Dray, Tevian; Hellaby, Charles

1994-01-01

The divergence theorem in its usual form applies only to suitably smooth vector fields. For vector fields which are merely piecewise smooth, as is natural at a boundary between regions with different physical properties, one must patch together the divergence theorem applied separately in each region. We give an elegant derivation of the resulting "patchwork divergence theorem" which is independent of the metric signature in either region, and which is thus valid if the signature changes. (PA...

Mass generation and the problem of seagull divergences

International Nuclear Information System (INIS)

Figueiredo, C. T.; Aguilar, A. C.

2016-01-01

The gluon mass generation is a purely non-perturbative effect, and the natural framework to study it in the continuum are the Schwinger-Dyson equations (SDEs) of the theory. At the level of the SDEs the generation of such a mass is associated with the existence of infrared finite solutions for the gluon propagator. From the theoretical point of view, the dynamical gluon mass generation has been traditionally plagued with seagull divergences. In this work, we will review how such divergences can be eliminated completely by virtue of a characteristic identity, valid in dimensional regularization. As a pedagogical example, we will first discuss in the context of scalar QED how it is possible to eliminate all seagull divergences, by triggering the aforementioned special identity, which enforces the masslessness of the photon. Then, we will discuss what happens in QCD and present an Ansatz for the three gluon vertex, which completely eliminates all seagull divergences and at same time allows for the possibility of a dynamical gluon mass generation. (paper)

On infrared divergences

International Nuclear Information System (INIS)

Parisi, G.

1979-01-01

The structure of infrared divergences is studied in superrenormalizable interactions. It is conjectured that there is an extension of the Bogoliubov-Parasiuk-Hepp theorem which copes also with infrared divergences. The consequences of this conjecture on the singularities of the Borel transform in a massless asymptotic free field theory are discussed. The application of these ideas to gauge theories is briefly discussed. (Auth.)

String loop divergences and effective lagrangians

International Nuclear Information System (INIS)

Fischler, W.; Klebanov, I.; Susskind, L.

1988-01-01

We isolate logarithmic divergences from bosonic string amplitudes on a disc. These divergences are compared with 'tadpole' divergences in the effective field theory, with a covariant cosmological term implied by the counting of string coupling constants. We find an inconsistency between the two. This might be a problem in eliminating divergences from the bosonic string. (orig.)

Statistical inference based on divergence measures

CERN Document Server

Pardo, Leandro

2005-01-01

The idea of using functionals of Information Theory, such as entropies or divergences, in statistical inference is not new. However, in spite of the fact that divergence statistics have become a very good alternative to the classical likelihood ratio test and the Pearson-type statistic in discrete models, many statisticians remain unaware of this powerful approach.Statistical Inference Based on Divergence Measures explores classical problems of statistical inference, such as estimation and hypothesis testing, on the basis of measures of entropy and divergence. The first two chapters form an overview, from a statistical perspective, of the most important measures of entropy and divergence and study their properties. The author then examines the statistical analysis of discrete multivariate data with emphasis is on problems in contingency tables and loglinear models using phi-divergence test statistics as well as minimum phi-divergence estimators. The final chapter looks at testing in general populations, prese...

Gauge-invariance and infrared divergences in the luminosity distance

International Nuclear Information System (INIS)

Biern, Sang Gyu; Yoo, Jaiyul

2017-01-01

Measurements of the luminosity distance have played a key role in discovering the late-time cosmic acceleration. However, when accounting for inhomogeneities in the Universe, its interpretation has been plagued with infrared divergences in its theoretical predictions, which are in some cases used to explain the cosmic acceleration without dark energy. The infrared divergences in most calculations are artificially removed by imposing an infrared cut-off scale. We show that a gauge-invariant calculation of the luminosity distance is devoid of such divergences and consistent with the equivalence principle, eliminating the need to impose a cut-off scale. We present proper numerical calculations of the luminosity distance using the gauge-invariant expression and demonstrate that the numerical results with an ad hoc cut-off scale in previous calculations have negligible systematic errors as long as the cut-off scale is larger than the horizon scale. We discuss the origin of infrared divergences and their cancellation in the luminosity distance.

Gauge-invariance and infrared divergences in the luminosity distance

Energy Technology Data Exchange (ETDEWEB)

Biern, Sang Gyu; Yoo, Jaiyul, E-mail: sgbiern@physik.uzh.ch, E-mail: jyoo@physik.uzh.ch [Center for Theoretical Astrophysics and Cosmology, Institute for Computational Science, University of Zürich, Winterthurerstrasse 190, CH-8057, Zürich (Switzerland)

2017-04-01

Measurements of the luminosity distance have played a key role in discovering the late-time cosmic acceleration. However, when accounting for inhomogeneities in the Universe, its interpretation has been plagued with infrared divergences in its theoretical predictions, which are in some cases used to explain the cosmic acceleration without dark energy. The infrared divergences in most calculations are artificially removed by imposing an infrared cut-off scale. We show that a gauge-invariant calculation of the luminosity distance is devoid of such divergences and consistent with the equivalence principle, eliminating the need to impose a cut-off scale. We present proper numerical calculations of the luminosity distance using the gauge-invariant expression and demonstrate that the numerical results with an ad hoc cut-off scale in previous calculations have negligible systematic errors as long as the cut-off scale is larger than the horizon scale. We discuss the origin of infrared divergences and their cancellation in the luminosity distance.

Divergent thinking and constructing episodic simulations.

Science.gov (United States)

Addis, Donna Rose; Pan, Ling; Musicaro, Regina; Schacter, Daniel L

2016-01-01

Divergent thinking likely plays an important role in simulating autobiographical events. We investigated whether divergent thinking is differentially associated with the ability to construct detailed imagined future and imagined past events as opposed to recalling past events. We also examined whether age differences in divergent thinking might underlie the reduced episodic detail generated by older adults. The richness of episodic detail comprising autobiographical events in young and older adults was assessed using the Autobiographical Interview. Divergent thinking abilities were measured using the Alternative Uses Task. Divergent thinking was significantly associated with the amount of episodic detail for imagined future events. Moreover, while age was significantly associated with imagined episodic detail, this effect was strongly related to age-related changes in episodic retrieval rather than divergent thinking.

Linkographic Evidence for Concurrent Divergent and Convergent Thinking in Creative Design

Science.gov (United States)

Goldschmidt, Gabriela

2016-01-01

For a long time, the creativity literature has stressed the role of divergent thinking in creative endeavor. More recently, it has been recognized that convergent thinking also has a role in creativity, and the design literature, which sees design as a creative activity a priori, has largely adopted this view: Divergent and convergent thinking are…

Anofelinos de Santa Catarina (Diptera: Culicidae, Brasil Anophelines of Santa Catarina (Diptera: Culicidae, Brazil

Directory of Open Access Journals (Sweden)

Maria da Graça Teixeira Portes

2010-04-01

likelihood of reintroduction of the disease. METHODS: The following data were used: the database of the Entomology Group of the National Health Foundation, Santa Catarina (ACCES, 1997-2000; the epidemiological surveillance information system of the Health Surveillance Department (Malaria/SC; and the notifiable disease information system (SINAN/SC. These data were transferred to and analyzed in the Microsoft Office Excel 2007 software. RESULTS: Collections were carried out in 48 municipalities and 159 localities, and 12,310 culicids, 11,546 anophelines (93.7% and 764 others (6.2% were identified. Three subgenera and 13 species of anophelines were identified. CONCLUSIONS: Given that in the municipalities investigated, important vectors such as Anopheles cruzii and Anopheles albitasis were found to be present, with movements of infected individuals from endemic areas, these areas can be considered to be receptive and vulnerable to malaria. These species are suspected of being responsible for malaria transmission in this region, especially in the municipalities of Gaspar, Indaial and Rodeio.

Relations between dissipated work in non-equilibrium process and the family of Rényi divergences

International Nuclear Information System (INIS)

Wei, Bo-Bo; Plenio, M B

2017-01-01

In this paper, we establish a general relation which directly links the dissipated work done on a system driven arbitrarily far from equilibrium, a fundamental quantity in thermodynamics, and the family of Rényi divergences between two states along the forward and reversed dynamics, a fundamental concept in information theory. Specifically, we find that the generating function of the dissipated work under an arbitrary time-dependent driving is related to the family of Rényi divergences between a non-equilibrium state along the forward process and a non-equilibrium state along its time-reversed process. This relation is a consequence of the principle of conservation of information and time reversal symmetry and is universally applicable to both finite classical system and finite quantum system under arbitrary driving process. The significance of the relation between the generating function of dissipated work and the family of Rényi divergences are two fold. On the one hand, the relation establishes that the macroscopic entropy production and its fluctuations are determined by the family of Rényi divergences, a measure of distinguishability of two states, between a microscopic process and its time reversal. On the other hand, this relation tells us that we can extract the family of Renyi divergences from the work measurement in a microscopic process. For classical systems the work measurement is straightforward, from which the family of Rényi divergences can be obtained; for quantum systems under time-dependent driving the characteristic function of work distributions can be measured from Ramsey interferences of a single spin, then we can extract the family of Renyi divergences from Ramsey interferences of a single spin. (paper)

Hamiltonian representation of divergence-free fields

International Nuclear Information System (INIS)

Boozer, A.H.

1984-11-01

Globally divergence-free fields, such as the magnetic field and the vorticity, can be described by a two degree of freedom Hamiltonian. The Hamiltonian function provides a complete topological description of the field lines. The formulation also separates the dissipative and inertial time scale evolution of the magnetic and the vorticity fields

Extensive homology of chicken macrochromosomes in the karyotypes of Trachemys scripta elegans and Crocodylus niloticus revealed by chromosome painting despite long divergence times.

Science.gov (United States)

Kasai, F; O'Brien, P C M; Martin, S; Ferguson-Smith, M A

2012-01-01

We report extensive chromosome homology revealed by chromosome painting between chicken (Gallus gallus domesticus, GGA, 2n = 78) macrochromosomes (representing 70% of the chicken genome) and the chromosomes of a turtle, the red-eared slider (Trachemys scripta elegans, TSC, 2n = 50), and the Nile crocodile (Crocodylus niloticus, CNI, 2n = 32). Our data show that GGA1-8 arms seem to be conserved in the arms of TSC chromosomes, GGA1-2 arms are separated and homologous to CNI1p, 3q, 4q and 5q. In addition to GGAZ homologues in our previous study, large-scale GGA autosome syntenies have been conserved in turtle and crocodile despite hundreds of millions of years divergence time. Based on phylogenetic hypotheses that crocodiles diverged after the divergence of birds and turtles, our results in CNI suggest that GGA1-2 and TSC1-2 represent the ancestral state and that chromosome fissions followed by fusions have been the mechanisms responsible for the reduction of chromosome number in crocodiles. Copyright © 2012 S. Karger AG, Basel.

Little evidence for dynamic divergences in ultraviscous molecular liquids

DEFF Research Database (Denmark)

Hecksher, Tina; Nielsen, Albena; Olsen, Niels Boye

2008-01-01

The physics of the ultraviscous liquid phase preceding glass formation continues to pose major problems that remain unsolved. It is actively debated, for instance, whether the marked increase of the relaxation time reflects an underlying phase transition to a state of infinite relaxation time....... To elucidate the empirical evidence for this intriguing scenario, some of the most accurate relaxationtime data available for any class of ultraviscous liquids-those obtained by dielectric relaxation experiments on organic liquids just above the glass transition-were compiled. Analysis of data for 42 liquids...... shows that there is no compelling evidence for the Vogel-Fulcher-Tammann (VFT) prediction that the relaxation time diverges at a finite temperature.We conclude that theories with a dynamic divergence of the VFT formlack a direct experimental basis....

Chained Kullback-Leibler Divergences

Science.gov (United States)

Pavlichin, Dmitri S.; Weissman, Tsachy

2017-01-01

We define and characterize the “chained” Kullback-Leibler divergence minw D(p‖w) + D(w‖q) minimized over all intermediate distributions w and the analogous k-fold chained K-L divergence min D(p‖wk−1) + … + D(w2‖w1) + D(w1‖q) minimized over the entire path (w1,…,wk−1). This quantity arises in a large deviations analysis of a Markov chain on the set of types – the Wright-Fisher model of neutral genetic drift: a population with allele distribution q produces offspring with allele distribution w, which then produce offspring with allele distribution p, and so on. The chained divergences enjoy some of the same properties as the K-L divergence (like joint convexity in the arguments) and appear in k-step versions of some of the same settings as the K-L divergence (like information projections and a conditional limit theorem). We further characterize the optimal k-step “path” of distributions appearing in the definition and apply our findings in a large deviations analysis of the Wright-Fisher process. We make a connection to information geometry via the previously studied continuum limit, where the number of steps tends to infinity, and the limiting path is a geodesic in the Fisher information metric. Finally, we offer a thermodynamic interpretation of the chained divergence (as the rate of operation of an appropriately defined Maxwell’s demon) and we state some natural extensions and applications (a k-step mutual information and k-step maximum likelihood inference). We release code for computing the objects we study. PMID:29130024

Selection is stronger in early-versus-late stages of divergence in a Neotropical livebearing fish.

Science.gov (United States)

Ingley, Spencer J; Johnson, Jerald B

2016-03-01

How selection acts to drive trait evolution at different stages of divergence is of fundamental importance in our understanding of the origins of biodiversity. Yet, most studies have focused on a single point along an evolutionary trajectory. Here, we provide a case study evaluating the strength of divergent selection acting on life-history traits at early-versus-late stages of divergence in Brachyrhaphis fishes. We find that the difference in selection is stronger in the early-diverged population than the late-diverged population, and that trait differences acquired early are maintained over time. © 2016 The Author(s).

Neural Mechanisms of Episodic Retrieval Support Divergent Creative Thinking.

Science.gov (United States)

Madore, Kevin P; Thakral, Preston P; Beaty, Roger E; Addis, Donna Rose; Schacter, Daniel L

2017-11-17

Prior research has indicated that brain regions and networks that support semantic memory, top-down and bottom-up attention, and cognitive control are all involved in divergent creative thinking. Kernels of evidence suggest that neural processes supporting episodic memory-the retrieval of particular elements of prior experiences-may also be involved in divergent thinking, but such processes have typically been characterized as not very relevant for, or even a hindrance to, creative output. In the present study, we combine functional magnetic resonance imaging with an experimental manipulation to test formally, for the first time, episodic memory's involvement in divergent thinking. Following a manipulation that facilitates detailed episodic retrieval, we observed greater neural activity in the hippocampus and stronger connectivity between a core brain network linked to episodic processing and a frontoparietal brain network linked to cognitive control during divergent thinking relative to an object association control task that requires little divergent thinking. Stronger coupling following the retrieval manipulation extended to a subsequent resting-state scan. Neural effects of the episodic manipulation were consistent with behavioral effects of enhanced idea production on divergent thinking but not object association. The results indicate that conceptual frameworks should accommodate the idea that episodic retrieval can function as a component process of creative idea generation, and highlight how the brain flexibly utilizes the retrieval of episodic details for tasks beyond simple remembering. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Collinearity, convergence and cancelling infrared divergences

International Nuclear Information System (INIS)

Lavelle, Martin; McMullan, David

2006-01-01

The Lee-Nauenberg theorem is a fundamental quantum mechanical result which provides the standard theoretical response to the problem of collinear and infrared divergences. Its argument, that the divergences due to massless charged particles can be removed by summing over degenerate states, has been successfully applied to systems with final state degeneracies such as LEP processes. If there are massless particles in both the initial and final states, as will be the case at the LHC, the theorem requires the incorporation of disconnected diagrams which produce connected interference effects at the level of the cross-section. However, this aspect of the theory has never been fully tested in the calculation of a cross-section. We show through explicit examples that in such cases the theorem introduces a divergent series of diagrams and hence fails to cancel the infrared divergences. It is also demonstrated that the widespread practice of treating soft infrared divergences by the Bloch-Nordsieck method and handling collinear divergences by the Lee-Nauenberg method is not consistent in such cases

Creativity and Memory: Effects of an Episodic-Specificity Induction on Divergent Thinking.

Science.gov (United States)

Madore, Kevin P; Addis, Donna Rose; Schacter, Daniel L

2015-09-01

People produce more episodic details when imagining future events and solving means-end problems after receiving an episodic-specificity induction-brief training in recollecting details of a recent event-than after receiving a control induction not focused on episodic retrieval. Here we show for the first time that an episodic-specificity induction also enhances divergent creative thinking. In Experiment 1, participants exhibited a selective boost on a divergent-thinking task (generating unusual uses of common objects) after a specificity induction compared with a control induction; by contrast, performance following the two inductions was similar on an object association task thought to involve little divergent thinking. In Experiment 2, we replicated the specificity-induction effect on divergent thinking using a different control induction, and also found that participants performed similarly on a convergent-thinking task following the two inductions. These experiments provide novel evidence that episodic memory is involved in divergent creative thinking. © The Author(s) 2015.

A New Study of Two Divergence Metrics for Change Detection in Data Streams

KAUST Repository

Qahtan, Abdulhakim Ali Ali; Wang, Suojin; Carroll, Raymond; Zhang, Xiangliang

2014-01-01

Streaming data are dynamic in nature with frequent changes. To detect such changes, most methods measure the difference between the data distributions in a current time window and a reference window. Divergence metrics and density estimation are required to measure the difference between the data distributions. Our study shows that the Kullback-Leibler (KL) divergence, the most popular metric for comparing distributions, fails to detect certain changes due to its asymmetric property and its dependence on the variance of the data. We thus consider two metrics for detecting changes in univariate data streams: a symmetric KL-divergence and a divergence metric measuring the intersection area of two distributions. The experimental results show that these two metrics lead to more accurate results in change detection than baseline methods such as Change Finder and using conventional KL-divergence.

A New Study of Two Divergence Metrics for Change Detection in Data Streams

KAUST Repository

Qahtan, Abdulhakim Ali Ali

2014-08-01

Streaming data are dynamic in nature with frequent changes. To detect such changes, most methods measure the difference between the data distributions in a current time window and a reference window. Divergence metrics and density estimation are required to measure the difference between the data distributions. Our study shows that the Kullback-Leibler (KL) divergence, the most popular metric for comparing distributions, fails to detect certain changes due to its asymmetric property and its dependence on the variance of the data. We thus consider two metrics for detecting changes in univariate data streams: a symmetric KL-divergence and a divergence metric measuring the intersection area of two distributions. The experimental results show that these two metrics lead to more accurate results in change detection than baseline methods such as Change Finder and using conventional KL-divergence.

A scalable block-preconditioning strategy for divergence-conforming B-spline discretizations of the Stokes problem

KAUST Repository

Cortes, Adriano Mauricio; Dalcin, Lisandro; Sarmiento, Adel; Collier, N.; Calo, Victor M.

2016-01-01

The recently introduced divergence-conforming B-spline discretizations allow the construction of smooth discrete velocity-pressure pairs for viscous incompressible flows that are at the same time inf−supinf−sup stable and pointwise divergence

Merit-order effects of renewable energy and price divergence in California’s day-ahead and real-time electricity markets

International Nuclear Information System (INIS)

Woo, C.K.; Moore, J.; Schneiderman, B.; Ho, T.; Olson, A.; Alagappan, L.; Chawla, K.; Toyama, N.; Zarnikau, J.

2016-01-01

We answer two policy questions: (1) what are the estimated merit-order effects of renewable energy in the California Independent System Operator’s (CAISO’s) day-ahead market (DAM) and real-time market (RTM)? and (2) what causes the hourly DAM and RTM prices to systematically diverge? The first question is timely and relevant because if the merit-order effect estimates are small, California’s renewable energy development is of limited help in cutting electricity consumers’ bills but also has a lesser adverse impact on the state’s investment incentive for natural-gas-fired generation. The second question is related to the efficient market hypothesis under which the hourly RTM and DAM prices tend to converge. Using a sample of about 21,000 hourly observations of CAISO market prices and their fundamental drivers during 12/12/2012–04/30/2015, we document statistically significant estimates (p-value≤0.01) for the DAM and RTM merit-order effects. This finding lends support to California’s adopted procurement process to provide sufficient investment incentives for natural-gas-fired generation. We document that the RTM-DAM price divergence partly depends on the CASIO’s day-ahead forecast errors for system loads and renewable energy. This finding suggests that improving the performance of the CAISO’s day-ahead forecasts can enhance trading efficiency in California’s DAM and RTM electricity markets. - Highlights: •Estimate the day-ahead and real-time merit-order effects of renewable energy in California. •Document statistically significant merit-order effects of solar and wind energy. •Document the difference between the day-ahead and real-time prices. •Attribute the price differences to forecast errors for load, solar and wind energy. •Discuss the evidence’s implications for California’s energy policy.

Linear energy divergences in Coulomb gauge QCD

OpenAIRE

Andrasi, A.

2011-01-01

The structure of linear energy divergences is analysed on the example of one graph to 3-loop order. Such dangerous divergences do cancel when all graphs are added, but next to leading divergences do not cancel out.

Predictors for reproductive isolation in a ring species complex following genetic and ecological divergence.

Science.gov (United States)

Pereira, Ricardo J; Monahan, William B; Wake, David B

2011-07-06

Reproductive isolation (RI) is widely accepted as an important "check point" in the diversification process, since it defines irreversible evolutionary trajectories. Much less consensus exists about the processes that might drive RI. Here, we employ a formal quantitative analysis of genetic interactions at several stages of divergence within the ring species complex Ensatina eschscholtzii in order to assess the relative contribution of genetic and ecological divergence for the development of RI. By augmenting previous genetic datasets and adding new ecological data, we quantify levels of genetic and ecological divergence between populations and test how they correlate with a restriction of genetic admixture upon secondary contact. Our results indicate that the isolated effect of ecological divergence between parental populations does not result in reproductively isolated taxa, even when genetic transitions between parental taxa are narrow. Instead, processes associated with overall genetic divergence are the best predictors of reproductive isolation, and when parental taxa diverge in nuclear markers we observe a complete cessation of hybridization, even to sympatric occurrence of distinct evolutionary lineages. Although every parental population has diverged in mitochondrial DNA, its degree of divergence does not predict the extent of RI. These results show that in Ensatina, the evolutionary outcomes of ecological divergence differ from those of genetic divergence. While evident properties of taxa may emerge via ecological divergence, such as adaptation to local environment, RI is likely to be a byproduct of processes that contribute to overall genetic divergence, such as time in geographic isolation, rather than being a direct outcome of local adaptation.

Guises and disguises of quadratic divergences

Energy Technology Data Exchange (ETDEWEB)

Cherchiglia, A.L., E-mail: adriano@fisica.ufmg.br [Departamento de Física, ICEx, Universidade Federal de Minas Gerais, P.O. BOX 702, 30.161-970, Belo Horizonte, MG (Brazil); Vieira, A.R., E-mail: arvieira@fisica.ufmg.br [Departamento de Física, ICEx, Universidade Federal de Minas Gerais, P.O. BOX 702, 30.161-970, Belo Horizonte, MG (Brazil); Hiller, Brigitte, E-mail: brigitte@teor.fis.uc.pt [Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-516 Coimbra (Portugal); Baêta Scarpelli, A.P., E-mail: scarpelli.apbs@dpf.gov.br [Setor Técnico-Científico, Departamento de Polícia Federal, Rua Hugo D’Antola, 95 - Lapa, São Paulo (Brazil); Sampaio, Marcos, E-mail: marcos.sampaio@durham.ac.uk [Departamento de Física, ICEx, Universidade Federal de Minas Gerais, P.O. BOX 702, 30.161-970, Belo Horizonte, MG (Brazil); Centre for Particle Theory, Department of Mathematical Sciences, Durham University, South Road Durham DH1 3LE (United Kingdom)

2014-12-15

In this contribution, we present a new perspective on the control of quadratic divergences in quantum field theory, in general, and in the Higgs naturalness problem, in particular. Our discussion is essentially based on an approach where UV divergences are parameterized, after being reduced to basic divergent integrals (BDI) in one internal momentum, as functions of a cutoff and a renormalization group scale λ. We illustrate our proposal with well-known examples, such as the gluon vacuum self energy of QCD and the Higgs decay in two photons within this approach. We also discuss frameworks in effective low-energy QCD models, where quadratic divergences are indeed fundamental.

Computer recognition of divergences in Feynman graphs

Energy Technology Data Exchange (ETDEWEB)

Calmet, J

1973-05-01

The program described recognizes whether or not a graph is divergent. It determines the kind of the divergences found: vacuum polarizations, electron self energies and vertices. it does not consider infrared divergences. The programming language used is REDUCE. A LISP version is also available. The nature of the divergences and their counter terms was extensively used to write down this program, therefore it is limited to the case of quantum electrodynamics. (auth)

Genetic divergence of common bean cultivars.

Science.gov (United States)

Veloso, J S; Silva, W; Pinheiro, L R; Dos Santos, J B; Fonseca, N S; Euzebio, M P

2015-09-22

The aim of this study was to evaluate genetic divergence in the 'Carioca' (beige with brown stripes) common bean cultivar used by different institutions and in 16 other common bean cultivars used in the Rede Cooperativa de Pesquisa de Feijão (Cooperative Network of Common Bean Research), by using simple sequence repeats associated with agronomic traits that are highly distributed in the common bean genome. We evaluated 22 polymorphic loci using bulks containing DNA from 30 plants. There was genetic divergence among the Carioca cultivar provided by the institutions. Nevertheless, there was lower divergence among them than among the other cultivars. The cultivar used by Instituto Agronômico do Paraná was the most divergent in relation to the Carioca samples. The least divergence was observed among the samples used by Universidade Federal de Lavras and by Embrapa Arroz e Feijão. Of all the cultivars, 'CNFP 10104' and 'BRSMG Realce' showed the greatest dissimilarity. The cultivars were separated in two groups of greatest similarity using the Structure software. Genetic variation among cultivars was greater than the variation within or between the groups formed. This fact, together with the high estimate of heterozygosity observed and the genetic divergence of the samples of the Carioca cultivar in relation to the original provided by Instituto Agronômico de Campinas, indicates a mixture of cultivars. The high divergence among cultivars provides potential for the utilization of this genetic variability in plant breeding.

Properties of classical and quantum Jensen-Shannon divergence

NARCIS (Netherlands)

J. Briët (Jop); P. Harremoës (Peter)

2009-01-01

htmlabstractJensen-Shannon divergence (JD) is a symmetrized and smoothed version of the most important divergence measure of information theory, Kullback divergence. As opposed to Kullback divergence it determines in a very direct way a metric; indeed, it is the square of a metric. We consider a

Genetic divergence is decoupled from ecological diversification in the Hawaiian Nesosydne planthoppers.

Science.gov (United States)

Roesch Goodman, Kari; Welter, Stephen C; Roderick, George K

2012-09-01

Adaptive radiation involves ecological shifts coupled with isolation of gene pools. However, we know little about what drives the initial stages of divergence. We study a system in which ecological diversification is found within a chronologically well-defined geological matrix to provide insight into this enigmatic phase of radiation. We tested the hypothesis that a period of geographic isolation precedes ecological specialization in an adaptive radiation of host-specialized Hawaiian planthoppers. We examined population structure and history using mitochondrial and multiple independent microsatellite loci in a species whose geographic distribution on the island of Hawaii enabled us to observe the chronology of divergence in its very earliest stages. We found that genetic divergence is associated with geographic features but not different plant hosts and that divergence times are very recent and on the same timescales as the dynamic geology of the island. Our results suggest an important role for geography in the dynamics of the early stages of divergence. © 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.

Jensen divergence based on Fisher’s information

International Nuclear Information System (INIS)

Sánchez-Moreno, P; Zarzo, A; Dehesa, J S

2012-01-01

The measure of Jensen–Fisher divergence between probability distributions is introduced and its theoretical grounds set up. This quantity, in contrast to the remaining Jensen divergences, grasps the fluctuations of the probability distributions because it is controlled by the (local) Fisher information, which is a gradient functional of the distribution. So it is appropriate and informative when studying the similarity of distributions, mainly for those having oscillatory character. The new Jensen–Fisher divergence shares with the Jensen–Shannon divergence the following properties: non-negativity, additivity when applied to an arbitrary number of probability densities, symmetry under exchange of these densities, vanishing under certain conditions and definiteness even when these densities present non-common zeros. Moreover, the Jensen–Fisher divergence is shown to be expressed in terms of the relative Fisher information as the Jensen–Shannon divergence does in terms of the Kullback–Leibler or relative Shannon entropy. Finally, the Jensen–Shannon and Jensen–Fisher divergences are compared for the following three large, non-trivial and qualitatively different families of probability distributions: the sinusoidal, generalized gamma-like and Rakhmanov–Hermite distributions, which are closely related to the quantum-mechanical probability densities of numerous physical systems. (paper)

Divergence-ratio axi-vision camera (Divcam): A distance mapping camera

International Nuclear Information System (INIS)

Iizuka, Keigo

2006-01-01

A novel distance mapping camera the divergence-ratio axi-vision camera (Divcam) is proposed. The decay rate of the illuminating light with distance due to the divergence of the light is used as means of mapping the distance. Resolutions of 10 mm over a range of meters and 0.5 mm over a range of decimeters were achieved. The special features of this camera are its high resolution real-time operation, simplicity, compactness, light weight, portability, and yet low fabrication cost. The feasibility of various potential applications is also included

Verbal and visual divergent thinking in aging.

Science.gov (United States)

Palmiero, Massimiliano; Nori, Raffaella; Piccardi, Laura

2017-04-01

According to the peak and decline model divergent thinking declines at a specific age (in or after middle age). However, if divergent thinking declines steadily in aging still has to be clarified. In order to explore the age-related changes in verbal and visual divergent thinking, in the present study a sample of 159 participants was divided in five age groups: young adults (18-35 years), middle-aged adults (36-55), young old (56-74), old (75-85) and the oldest-old (86-98). Two divergent thinking tasks were administered: the alternative uses for cardboard boxes, aimed at assessing verbal ideational fluency, flexibility and originality; the completion drawing task, aimed at assessing visual ideational fluency, flexibility and originality. Results showed that after peaking in the young adult group (20-35 years) all components of verbal and visual divergent thinking stabilized in the middle-aged adult group (36-55 years) and then started declining in the young old group (56-75). Interestingly, all components were found to be preserved after declining. Yet, verbal and visual divergent thinking were found at the same extent across age groups, with the exception of visual ideational fluency, that was higher in the young old group, the old group and the oldest-old group than verbal ideational fluency. These results support the idea that divergent thinking does not decline steadily in the elderly. Given that older people can preserve to some extent verbal and visual divergent thinking, these findings have important implications for active aging, that is, divergent thinking might be fostered in aging in order to prevent the cognitive decline.

Quadratic divergences and dimensional regularisation

International Nuclear Information System (INIS)

Jack, I.; Jones, D.R.T.

1990-01-01

We present a detailed analysis of quadratic and quartic divergences in dimensionally regulated renormalisable theories. We perform explicit three-loop calculations for a general theory of scalars and fermions. We find that the higher-order quartic divergences are related to the lower-order ones by the renormalisation group β-functions. (orig.)

The effects of medieval dams on genetic divergence and demographic history in brown trout populations

DEFF Research Database (Denmark)

Hansen, Michael Møller; Limborg, Morten; Ferchaud, A.-L.

2014-01-01

Background: Habitat fragmentation has accelerated within the last century, but may have been ongoing over longer time scales. We analyzed the timing and genetic consequences of fragmentation in two isolated lake-dwelling brown trout populations. They are from the same river system (the Gudenå River......, Denmark) and have been isolated from downstream anadromous trout by dams established ca. 600-800 years ago. For reference, we included ten other anadromous populations and two hatchery strains. Based on analysis of 44 microsatellite loci we investigated if the lake populations have been naturally...... genetically differentiated from anadromous trout for thousands of years, or have diverged recently due to the establishment of dams. Results: Divergence time estimates were based on 1) Approximate Bayesian Computation and 2) a coalescent-based isolation-with-gene-flow model. Both methods suggested divergence...

Cancellation of soft and collinear divergences in noncommutative QED

International Nuclear Information System (INIS)

Mirza, B.; Zarei, M.

2006-01-01

In this paper, we investigate the behavior of noncommutative IR divergences and will also discuss their cancellation in the physical cross sections. The commutative IR (soft) divergences existing in the nonplanar diagrams will be examined in order to prove an all-order cancellation of these divergences using the Weinberg's method. In noncommutative QED, collinear divergences due to triple photon splitting vertex, were encountered, which are shown to be canceled out by the noncommutative version of KLN theorem. This guarantees that there is no mixing between the Collinear, soft divergences and noncommutative IR divergences

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.

Divergence Palsy due to Divalproex and Oxcarbazepine.

Science.gov (United States)

Bouffard, Marc Albert; Caplan, Louis R; Torun, Nurhan

This case series is the first to describe divergence palsy as an adverse effect of antiepileptic drug use. Diplopia is a common adverse effect of antiepileptic drugs, but no explanatory motility deficit has ever been reported. We present 2 patients, 1 on oxcarbazepine and 1 on divalproex, each with a normal examination result between spells and divergency palsy when symptomatic. Discontinuation of the antiepileptic medication led to resolution of the episodes in both cases. Rechallenge with the offending agent after washout in one patient resulted in recurrence of diplopia and divergence palsy, both resolving after subsequent withdrawal of the antiepileptic. Antiepileptic drugs may cause divergence palsy.

Beam divergence scaling in neutral beam injectors

International Nuclear Information System (INIS)

Holmes, A.J.T.

1976-01-01

One of the main considerations in the design of neutral beam injectors is to monimize the divergence of the primary ion beam and hence maximize the beam transport and minimize the input of thermal gas. Experimental measurements of the divergence of a cylindrical ion beam are presented and these measurements are used to analyze the major components of ion beam divergence, namely: space charge expansion, gas-ion scattering, emittance and optical aberrations. The implication of these divergence components in the design of a neutral beam injector system is discussed and a method of maximizing the beam current is described for a given area of source plasma

Phylogeography, genetic structure and population divergence time of cheetahs in Africa and Asia: evidence for long-term geographic isolates

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Charruau, P; Fernandes, C; Orozco-terWengel, P; Peters, J; Hunter, L; Ziaie, H; Jourabchian, A; Jowkar, H; Schaller, G; Ostrowski, S; Vercammen, P; Grange, T; Schlötterer, C; Kotze, A; Geigl, E-M; Walzer, C; Burger, P A

2011-01-01

The cheetah (Acinonyx jubatus) has been described as a species with low levels of genetic variation. This has been suggested to be the consequence of a demographic bottleneck 10 000–12 000 years ago (ya) and also led to the assumption that only small genetic differences exist between the described subspecies. However, analysing mitochondrial DNA and microsatellites in cheetah samples from most of the historic range of the species we found relatively deep phylogeographic breaks between some of the investigated populations, and most of the methods assessed divergence time estimates predating the postulated bottleneck. Mitochondrial DNA monophyly and overall levels of genetic differentiation support the distinctiveness of Northern-East African cheetahs (Acinonyx jubatus soemmeringii). Moreover, combining archaeozoological and contemporary samples, we show that Asiatic cheetahs (Acinonyx jubatus venaticus) are unambiguously separated from African subspecies. Divergence time estimates from mitochondrial and nuclear data place the split between Asiatic and Southern African cheetahs (Acinonyx jubatus jubatus) at 32 000–67 000 ya using an average mammalian microsatellite mutation rate and at 4700–44 000 ya employing human microsatellite mutation rates. Cheetahs are vulnerable to extinction globally and critically endangered in their Asiatic range, where the last 70–110 individuals survive only in Iran. We demonstrate that these extant Iranian cheetahs are an autochthonous monophyletic population and the last representatives of the Asiatic subspecies A. j. venaticus. We advocate that conservation strategies should consider the uncovered independent evolutionary histories of Asiatic and African cheetahs, as well as among some African subspecies. This would facilitate the dual conservation priorities of maintaining locally adapted ecotypes and genetic diversity. PMID:21214655

Escort entropies and divergences and related canonical distribution

International Nuclear Information System (INIS)

Bercher, J.-F.

2011-01-01

We discuss two families of two-parameter entropies and divergences, derived from the standard Renyi and Tsallis entropies and divergences. These divergences and entropies are found as divergences or entropies of escort distributions. Exploiting the nonnegativity of the divergences, we derive the expression of the canonical distribution associated to the new entropies and a observable given as an escort-mean value. We show that this canonical distribution extends, and smoothly connects, the results obtained in nonextensive thermodynamics for the standard and generalized mean value constraints. -- Highlights: → Two-parameter entropies are derived from q-entropies and escort distributions. → The related canonical distribution is derived. → This connects and extends known results in nonextensive statistics.

The effects of Medieval dams on genetic divergence and demographic history in brown trout populations.

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Hansen, Michael M; Limborg, Morten T; Ferchaud, Anne-Laure; Pujolar, José-Martin

2014-06-05

Habitat fragmentation has accelerated within the last century, but may have been ongoing over longer time scales. We analyzed the timing and genetic consequences of fragmentation in two isolated lake-dwelling brown trout populations. They are from the same river system (the Gudenå River, Denmark) and have been isolated from downstream anadromous trout by dams established ca. 600-800 years ago. For reference, we included ten other anadromous populations and two hatchery strains. Based on analysis of 44 microsatellite loci we investigated if the lake populations have been naturally genetically differentiated from anadromous trout for thousands of years, or have diverged recently due to the establishment of dams. Divergence time estimates were based on 1) Approximate Bayesian Computation and 2) a coalescent-based isolation-with-gene-flow model. Both methods suggested divergence times ca. 600-800 years bp, providing strong evidence for establishment of dams in the Medieval as the factor causing divergence. Bayesian cluster analysis showed influence of stocked trout in several reference populations, but not in the focal lake and anadromous populations. Estimates of effective population size using a linkage disequilibrium method ranged from 244 to > 1,000 in all but one anadromous population, but were lower (153 and 252) in the lake populations. We show that genetic divergence of lake-dwelling trout in two Danish lakes reflects establishment of water mills and impassable dams ca. 600-800 years ago rather than a natural genetic population structure. Although effective population sizes of the two lake populations are not critically low they may ultimately limit response to selection and thereby future adaptation. Our results demonstrate that populations may have been affected by anthropogenic disturbance over longer time scales than normally assumed.

An investigation of merging and diverging cars on a multi-lane road using a cellular automation model

Science.gov (United States)

Jetto, K.; Ez-Zahraouy, H.; Benyoussef, A.

2012-11-01

In this paper, we have investigated two observed situations in a multi-lane road. The first one concerns a fast merging vehicle. The second situation is related to the case of a fast vehicle leaving the fastest lane back into the slowest lane and targeting a specific way out. We are interested in the relaxation time τ, i.e., which is the time that the merging (diverging) vehicle spends before reaching the desired lane. Using analytical treatment and numerical simulations for the NaSch model, we have found two states, namely, the free state in which the merging (diverging) vehicle reaches the desired lane, and the trapped state in which τ diverges. We have established phase diagrams for several values of the braking probability. In the second situation, we have shown that diverging from the fast lane targeting a specific way out is not a simple task. Even if the diverging vehicle is in the free phase, two different states can be distinguished. One is the critical state, in which the diverging car can probably reach the desired way out. The other is the safe state, in which the diverging car can surely reach the desired way out. In order to be in the safe state, we have found that the driver of the diverging car must know the critical distance (below which the way out will be out of his reach) in each lane. Furthermore, this critical distance depends on the density of cars, and it follows an exponential law.

Divergent Geophysical Evolution of Vesta and Ceres

Science.gov (United States)

Raymond, C. A.; Ermakov, A.; Castillo, J. C.; Fu, R. R.; McSween, H. Y., Jr.; McCord, T. B.; Park, R. S.; Russell, C. T.; De Sanctis, M. C.; Jaumann, R.; Konopliv, A. S.

2017-12-01

The Dawn mission explored two massive protoplanets in the main asteroid belt, Vesta and Ceres, that are fossils from the earliest epoch of solar system formation. Dawn's data provide evidence that these bodies formed very early, within the first few million years after CAIs, yet they followed divergent evolutionary paths. Vesta formed globally homogeneous distribution of minerals across the surface indicates that Ceres' interior experienced pervasive alteration. Topography and morphology of the surface reveals smoother, apparently resurfaced areas, generally at lower elevation, and rougher areas with greater relief. Local morphology such as crater floor deposits, isolated mountains, and enigmatic bright areas indicate recently active processes on Ceres, likely driven by brine cryovolcanism. Causes of the divergent evolution of these bodies include their accretionary environment, timing of accretion and size. Acknowledgements: Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract to the National Aeronautics and Space Administration.

Testing evolutionary hypotheses for phenotypic divergence using landscape genetics.

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Funk, W Chris; Murphy, Melanie A

2010-02-01

Understanding the evolutionary causes of phenotypic variation among populations has long been a central theme in evolutionary biology. Several factors can influence phenotypic divergence, including geographic isolation, genetic drift, divergent natural or sexual selection, and phenotypic plasticity. But the relative importance of these factors in generating phenotypic divergence in nature is still a tantalizing and unresolved problem in evolutionary biology. The origin and maintenance of phenotypic divergence is also at the root of many ongoing debates in evolutionary biology, such as the extent to which gene flow constrains adaptive divergence (Garant et al. 2007) and the relative importance of genetic drift, natural selection, and sexual selection in initiating reproductive isolation and speciation (Coyne & Orr 2004). In this issue, Wang & Summers (2010) test the causes of one of the most fantastic examples of phenotypic divergence in nature: colour pattern divergence among populations of the strawberry poison frog (Dendrobates pumilio) in Panama and Costa Rica (Fig. 1). This study provides a beautiful example of the use of the emerging field of landscape genetics to differentiate among hypotheses for phenotypic divergence. Using landscape genetic analyses, Wang & Summers were able to reject the hypotheses that colour pattern divergence is due to isolation-by-distance (IBD) or landscape resistance. Instead, the hypothesis left standing is that colour divergence is due to divergent selection, in turn driving reproductive isolation among populations with different colour morphs. More generally, this study provides a wonderful example of how the emerging field of landscape genetics, which has primarily been applied to questions in conservation and ecology, now plays an essential role in evolutionary research.

Treatment of divergent expansions in scattering theory

International Nuclear Information System (INIS)

Gersten, A.; Malin, S.

1978-01-01

One of the biggest obstacles in applying quantum field theory to realistic scattering problems are the divergencies of pertubation expansions for large coupling constants and the divergencies of partial wave expansions for massless particles exchanges. There exist, however, methods of summation of the divergent expansions which can lead to significant application in physics. In this paper we treat the problem of summing such expansions using three methods: (i) a generalization of the Pade approximation to the multivariable case. The suggested definition is unique and preserves unitarity. (ii) The summation of divergent partial waves for arbitrary spins. (iii) A successful application of a series inversion to the 3 P 1 nucleon-nucleon phase shift up to 200 MeV. (orig./WL) [de

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.

Atmospheric horizontal divergence and diffusion

International Nuclear Information System (INIS)

Castans, M.

1981-01-01

The action of horizontal divergence on diffusion near the ground is established through.a very simple flow model. The shape of the well-known Pasquill-Gifford-Turner curves, that apparently take account in some way of divergence, is justified. The possibility of explaining the discre--pancies between the conventional straight line model and experimental results, mainly under low-wind-speed satable conditions, is considered. Some hints for further research are made. (auth.)

Holstein-Friesian calves selected for divergence in residual feed intake during growth exhibited significant but reduced residual feed intake divergence in their first lactation.

Science.gov (United States)

Macdonald, K A; Pryce, J E; Spelman, R J; Davis, S R; Wales, W J; Waghorn, G C; Williams, Y J; Marett, L C; Hayes, B J

2014-03-01

Residual feed intake (RFI), as a measure of feed conversion during growth, was estimated for around 2,000 growing Holstein-Friesian heifer calves aged 6 to 9 mo in New Zealand and Australia, and individuals from the most and least efficient deciles (low and high RFI phenotypes) were retained. These animals (78 New Zealand cows, 105 Australian cows) were reevaluated during their first lactation to determine if divergence for RFI observed during growth was maintained during lactation. Mean daily body weight (BW) gain during assessment as calves had been 0.86 and 1.15 kg for the respective countries, and the divergence in RFI between most and least efficient deciles for growth was 21% (1.39 and 1.42 kg of dry matter, for New Zealand and Australia, respectively). At the commencement of evaluation during lactation, the cows were aged 26 to 29 mo. All were fed alfalfa and grass cubes; it was the sole diet in New Zealand, whereas 6 kg of crushed wheat/d was also fed in Australia. Measurements of RFI during lactation occurred for 34 to 37 d with measurements of milk production (daily), milk composition (2 to 3 times per week), BW and BW change (1 to 3 times per week), as well as body condition score (BCS). Daily milk production averaged 13.8 kg for New Zealand cows and 20.0 kg in Australia. No statistically significant differences were observed between calf RFI decile groups for dry matter intake, milk production, BW change, or BCS; however a significant difference was noted between groups for lactating RFI. Residual feed intake was about 3% lower for lactating cows identified as most efficient as growing calves, and no negative effects on production were observed. These results support the hypothesis that calves divergent for RFI during growth are also divergent for RFI when lactating. The causes for this reduced divergence need to be investigated to ensure that genetic selection programs based on low RFI (better efficiency) are robust. Copyright © 2014 American Dairy

Divergence-free MHD on unstructured meshes using high order finite volume schemes based on multidimensional Riemann solvers

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Balsara, Dinshaw S.; Dumbser, Michael

2015-10-01

Several advances have been reported in the recent literature on divergence-free finite volume schemes for Magnetohydrodynamics (MHD). Almost all of these advances are restricted to structured meshes. To retain full geometric versatility, however, it is also very important to make analogous advances in divergence-free schemes for MHD on unstructured meshes. Such schemes utilize a staggered Yee-type mesh, where all hydrodynamic quantities (mass, momentum and energy density) are cell-centered, while the magnetic fields are face-centered and the electric fields, which are so useful for the time update of the magnetic field, are centered at the edges. Three important advances are brought together in this paper in order to make it possible to have high order accurate finite volume schemes for the MHD equations on unstructured meshes. First, it is shown that a divergence-free WENO reconstruction of the magnetic field can be developed for unstructured meshes in two and three space dimensions using a classical cell-centered WENO algorithm, without the need to do a WENO reconstruction for the magnetic field on the faces. This is achieved via a novel constrained L2-projection operator that is used in each time step as a postprocessor of the cell-centered WENO reconstruction so that the magnetic field becomes locally and globally divergence free. Second, it is shown that recently-developed genuinely multidimensional Riemann solvers (called MuSIC Riemann solvers) can be used on unstructured meshes to obtain a multidimensionally upwinded representation of the electric field at each edge. Third, the above two innovations work well together with a high order accurate one-step ADER time stepping strategy, which requires the divergence-free nonlinear WENO reconstruction procedure to be carried out only once per time step. The resulting divergence-free ADER-WENO schemes with MuSIC Riemann solvers give us an efficient and easily-implemented strategy for divergence-free MHD on

Using Dendritic Heat Maps to Simultaneously Display Genotype Divergence with Phenotype Divergence.

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Kellom, Matthew; Raymond, Jason

2016-01-01

The advancement of techniques to visualize and analyze large-scale sequencing datasets is an area of active research and is rooted in traditional techniques such as heat maps and dendrograms. We introduce dendritic heat maps that display heat map results over aligned DNA sequence clusters for a range of clustering cutoffs. Dendritic heat maps aid in visualizing the effects of group differences on clustering hierarchy and relative abundance of sampled sequences. Here, we artificially generate two separate datasets with simplified mutation and population growth procedures with GC content group separation to use as example phenotypes. In this work, we use the term phenotype to represent any feature by which groups can be separated. These sequences were clustered in a fractional identity range of 0.75 to 1.0 using agglomerative minimum-, maximum-, and average-linkage algorithms, as well as a divisive centroid-based algorithm. We demonstrate that dendritic heat maps give freedom to scrutinize specific clustering levels across a range of cutoffs, track changes in phenotype inequity across multiple levels of sequence clustering specificity, and easily visualize how deeply rooted changes in phenotype inequity are in a dataset. As genotypes diverge in sample populations, clusters are shown to break apart into smaller clusters at higher identity cutoff levels, similar to a dendrogram. Phenotype divergence, which is shown as a heat map of relative abundance bin response, may or may not follow genotype divergences. This joined view highlights the relationship between genotype and phenotype divergence for treatment groups. We discuss the minimum-, maximum-, average-, and centroid-linkage algorithm approaches to building dendritic heat maps and make a case for the divisive "top-down" centroid-based clustering methodology as being the best option visualize the effects of changing factors on clustering hierarchy and relative abundance.

Using Dendritic Heat Maps to Simultaneously Display Genotype Divergence with Phenotype Divergence.

Directory of Open Access Journals (Sweden)

Matthew Kellom

Full Text Available The advancement of techniques to visualize and analyze large-scale sequencing datasets is an area of active research and is rooted in traditional techniques such as heat maps and dendrograms. We introduce dendritic heat maps that display heat map results over aligned DNA sequence clusters for a range of clustering cutoffs. Dendritic heat maps aid in visualizing the effects of group differences on clustering hierarchy and relative abundance of sampled sequences. Here, we artificially generate two separate datasets with simplified mutation and population growth procedures with GC content group separation to use as example phenotypes. In this work, we use the term phenotype to represent any feature by which groups can be separated. These sequences were clustered in a fractional identity range of 0.75 to 1.0 using agglomerative minimum-, maximum-, and average-linkage algorithms, as well as a divisive centroid-based algorithm. We demonstrate that dendritic heat maps give freedom to scrutinize specific clustering levels across a range of cutoffs, track changes in phenotype inequity across multiple levels of sequence clustering specificity, and easily visualize how deeply rooted changes in phenotype inequity are in a dataset. As genotypes diverge in sample populations, clusters are shown to break apart into smaller clusters at higher identity cutoff levels, similar to a dendrogram. Phenotype divergence, which is shown as a heat map of relative abundance bin response, may or may not follow genotype divergences. This joined view highlights the relationship between genotype and phenotype divergence for treatment groups. We discuss the minimum-, maximum-, average-, and centroid-linkage algorithm approaches to building dendritic heat maps and make a case for the divisive "top-down" centroid-based clustering methodology as being the best option visualize the effects of changing factors on clustering hierarchy and relative abundance.

One-loop divergences in 6D, N=(1,0) SYM theory

Energy Technology Data Exchange (ETDEWEB)

Buchbinder, I.L. [Department of Theoretical Physics, Tomsk State Pedagogical University,634061, Tomsk (Russian Federation); National Research Tomsk State University,634050, Tomsk (Russian Federation); Ivanov, E.A. [Bogoliubov Laboratory of Theoretical Physics,JINR, 141980 Dubna, Moscow region (Russian Federation); Merzlikin, B.S. [Department of Theoretical Physics, Tomsk State Pedagogical University,634061, Tomsk (Russian Federation); Department of Higher Mathematics and Mathematical Physics,Tomsk Polytechnic University,634050, Tomsk (Russian Federation); Stepanyantz, K.V. [Department of Theoretical Physics, Moscow State University,119991, Moscow (Russian Federation)

2017-01-30

We consider, in the harmonic superspace approach, the six-dimensional N=(1,0) supersymmetric Yang-Mills gauge multiplet minimally coupled to a hypermultiplet in an arbitrary representation of the gauge group. Using the superfield proper-time and background-field techniques, we compute the divergent part of the one-loop effective action depending on both the gauge multiplet and the hypermultiplet. We demonstrate that in the particular case of N=(1,1) SYM theory, which corresponds to the hypermultiplet in the adjoint representation, all one-loop divergencies vanish, so that N=(1,1) SYM theory is one-loop finite off shell.

Transcriptome-wide patterns of divergence during allopatric evolution.

Science.gov (United States)

Pereira, Ricardo J; Barreto, Felipe S; Pierce, N Tessa; Carneiro, Miguel; Burton, Ronald S

2016-04-01

Recent studies have revealed repeated patterns of genomic divergence associated with species formation. Such patterns suggest that natural selection tends to target a set of available genes, but is also indicative that closely related taxa share evolutionary constraints that limit genetic variability. Studying patterns of genomic divergence among populations within the same species may shed light on the underlying evolutionary processes. Here, we examine transcriptome-wide divergence and polymorphism in the marine copepod Tigriopus californicus, a species where allopatric evolution has led to replicate sets of populations with varying degrees of divergence and hybrid incompatibility. Our analyses suggest that relatively small effective population sizes have resulted in an exponential decline of shared polymorphisms during population divergence and also facilitated the fixation of slightly deleterious mutations within allopatric populations. Five interpopulation comparisons at three different stages of divergence show that nonsynonymous mutations tend to accumulate in a specific set of proteins. These include proteins with central roles in cellular metabolism, such as those encoded in mtDNA, but also include an additional set of proteins that repeatedly show signatures of positive selection during allopatric divergence. Although our results are consistent with a contribution of nonadaptive processes, such as genetic drift and gene expression levels, generating repeatable patterns of genomic divergence in closely related taxa, they also indicate that adaptive evolution targeting a specific set of genes contributes to this pattern. Our results yield insights into the predictability of evolution at the gene level. © 2016 John Wiley & Sons Ltd.

Mechanisms of peripheral phylogeographic divergence in the indo-Pacific: lessons from the spiny lobster Panulirus homarus.

Science.gov (United States)

Farhadi, Ahmad; Jeffs, Andrew G; Farahmand, Hamid; Rejiniemon, Thankappan Sarasam; Smith, Greg; Lavery, Shane D

2017-08-18

There is increasing recognition of the concordance between marine biogeographic and phylogeographic boundaries. However, it is still unclear how population-level divergence translates into species-level divergence, and what are the principal factors that first initiate that divergence, and then maintain reproductive isolation. This study examines the likely forces driving population and lineage divergences in the broadly-distributed Indo-Pacific spiny lobster Panulirus homarus, which has peripheral divergent lineages in the west and east. The study focuses particularly on the West Indian Ocean, which is emerging as a region of unexpected diversity. Mitochondrial control region (mtCR) and COI sequences as well as genotypes of 9 microsatellite loci were examined in 410 individuals from 17 locations grouped into 7 regions from South Africa in the west, and eastward across to Taiwan and the Marquesas Islands. Phylogenetic and population-level analyses were used to test the significance and timing of divergences and describe the genetic relationships among populations. Analyses of the mtCR revealed high levels of divergence among the seven regions (Ф ST  = 0.594, P Indo-Pacific that helps drive some of the regions' recognized biogeographic boundaries.

Divergent Thinking and Age-Related Changes

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Palmiero, Massimiliano; Di Giacomo, Dina; Passafiume, Domenico

2014-01-01

Aging can affect cognition in different ways. The extent to which aging affects divergent thinking is unclear. In this study, younger and older adults were compared at the performance on the Torrance Test of Creative Thinking in visual and verbal form. Results showed that older adults can think divergently as younger participants, although they…

Two New Measures of Fuzzy Divergence and Their Properties

Directory of Open Access Journals (Sweden)

Om Parkash

2006-06-01

Full Text Available Several measures of directed divergence and their corresponding measures of fuzzy divergence are available in the exiting literature. Two new measures of fuzzy divergence have been developed and their desirable properties have been discussed.

Genetic, ecological and morphological divergence between populations of the endangered Mexican Sheartail hummingbird (Doricha eliza.

Directory of Open Access Journals (Sweden)

Yuyini Licona-Vera

Full Text Available The Mexican Sheartail (Doricha eliza, an endangered hummingbird, is endemic to Mexico where two populations have a disjunct distribution. One population is distributed along the northern tip of the Yucatan Peninsula whereas the other is mostly restricted to central Veracruz. Despite their disjunct distribution, previous work has failed to detect morphological or behavioral differences between these populations. Here we use variation in morphology, mtDNA and nuDNA sequences to determine the degree of morphological and molecular divergence between populations, their divergence time, and historical demography. We use species distribution modeling and niche divergence tests to infer the relative roles of vicariance and dispersal in driving divergence in the genus. Our Bayesian and maximum likelihood phylogenetic analyses revealed that Doricha eliza populations form a monophyletic clade and support their sister relationship with D. enicura. We found marked genetic differentiation, with reciprocal monophyly of haplotypes and highly restricted gene flow, supporting a history of isolation over the last 120,000 years. Genetic divergence between populations is consistent with the lack of overlap in environmental space and slight morphological differences between males. Our findings indicate that the divergence of the Veracruz and Yucatan populations is best explained by a combination of a short period of isolation exacerbated by subsequent divergence in climate conditions, and that rather than vicariance, the two isolated ranges of D. eliza are the product of recent colonization and divergence in isolation.

Structure of rapidity divergences in multi-parton scattering soft factors

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Vladimirov, Alexey

2018-04-01

We discuss the structure of rapidity divergences that are presented in the soft factors of transverse momentum dependent (TMD) factorization theorems. To provide the discussion on the most general level we consider soft factors for multi-parton scattering. We show that the rapidity divergences are result of the gluon exchanges with the distant transverse plane, and are structurally equivalent to the ultraviolet divergences. It allows to formulate and to prove the renormalization theorem for rapidity divergences. The proof is made with the help the conformal transformation which maps rapidity divergences to ultraviolet divergences. The theorem is the systematic form of the factorization of rapidity divergences, which is required for the definition of TMD parton distributions. In particular, the definition of multi parton distributions is presented. The equivalence of ultraviolet and rapidity divergences leads to the exact relation between soft and rapidity anomalous dimensions. Using this relation we derive the rapidity anomalous dimension at the three-loop order.

Pre- versus post-mass extinction divergence of Mesozoic marine reptiles dictated by time-scale dependence of evolutionary rates.

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Motani, Ryosuke; Jiang, Da-Yong; Tintori, Andrea; Ji, Cheng; Huang, Jian-Dong

2017-05-17

The fossil record of a major clade often starts after a mass extinction even though evolutionary rates, molecular or morphological, suggest its pre-extinction emergence (e.g. squamates, placentals and teleosts). The discrepancy is larger for older clades, and the presence of a time-scale-dependent methodological bias has been suggested, yet it has been difficult to avoid the bias using Bayesian phylogenetic methods. This paradox raises the question of whether ecological vacancies, such as those after mass extinctions, prompt the radiations. We addressed this problem by using a unique temporal characteristic of the morphological data and a high-resolution stratigraphic record, for the oldest clade of Mesozoic marine reptiles, Ichthyosauromorpha. The evolutionary rate was fastest during the first few million years of ichthyosauromorph evolution and became progressively slower over time, eventually becoming six times slower. Using the later slower rates, estimates of divergence time become excessively older. The fast, initial rate suggests the emergence of ichthyosauromorphs after the end-Permian mass extinction, matching an independent result from high-resolution stratigraphic confidence intervals. These reptiles probably invaded the sea as a new ecosystem was formed after the end-Permian mass extinction. Lack of information on early evolution biased Bayesian clock rates. © 2017 The Author(s).

One-loop divergences in the quantum theory of supergravity

International Nuclear Information System (INIS)

Nieuwenhuizen, P. van; Vermaseren, J.A.M.

1976-01-01

Supergravity does not lead to a finite quantum theory of gravitation when coupled to the spin 1, 1/2 matter multiplet. The S-matrix of photon-photon scattering diverges; its divergences are proportional to the square of the photon energy-momentum tensor, in agreement with electro-magnetic duality and chiral invariance. The graviton self-energy corrections are divergent in pure supergravity as well as in the coupled Maxwell-Einstein system and satisfy their Ward identity because the supersymmetry ghost field is commuting. The photon-graviton vertex corrections diverge, as expected from the non-invariance of the action under local scale transformations, and satisfy the equivalence principle at the quantum level. The photon self-energy is divergent. (Auth.)

Phylogenetic relationships and divergence dates of softshell turtles (Testudines: Trionychidae) inferred from complete mitochondrial genomes.

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Li, H; Liu, J; Xiong, L; Zhang, H; Zhou, H; Yin, H; Jing, W; Li, J; Shi, Q; Wang, Y; Liu, J; Nie, L

2017-05-01

The softshell turtles (Trionychidae) are one of the most widely distributed reptile groups in the world, and fossils have been found on all continents except Antarctica. The phylogenetic relationships among members of this group have been previously studied; however, disagreements regarding its taxonomy, its phylogeography and divergence times are still poorly understood as well. Here, we present a comprehensive mitogenomic study of softshell turtles. We sequenced the complete mitochondrial genomes of 10 softshell turtles, in addition to the GenBank sequence of Dogania subplana, Lissemys punctata, Trionyx triunguis, which cover all extant genera within Trionychidae except for Cyclanorbis and Cycloderma. These data were combined with other mitogenomes of turtles for phylogenetic analyses. Divergence time calibration and ancestral reconstruction were calculated using BEAST and RASP software, respectively. Our phylogenetic analyses indicate that Trionychidae is the sister taxon of Carettochelyidae, and support the monophyly of Trionychinae and Cyclanorbinae, which is consistent with morphological data and molecular analysis. Our phylogenetic analyses have established a sister taxon relationship between the Asian Rafetus and the Asian Palea + Pelodiscus + Dogania + Nilssonia + Amyda, whereas a previous study grouped the Asian Rafetus with the American Apalone. The results of divergence time estimates and area ancestral reconstruction show that extant Trionychidae originated in Asia at around 108 million years ago (MA), and radiations mainly occurred during two warm periods, namely Late Cretaceous-Early Eocene and Oligocene. By combining the estimated divergence time and the reconstructed ancestral area of softshell turtles, we determined that the dispersal of softshell turtles out of Asia may have taken three routes. Furthermore, the times of dispersal seem to be in agreement with the time of the India-Asia collision and opening of the Bering Strait, which

Sandwiched Rényi divergence satisfies data processing inequality

International Nuclear Information System (INIS)

Beigi, Salman

2013-01-01

Sandwiched (quantum) α-Rényi divergence has been recently defined in the independent works of Wilde et al. [“Strong converse for the classical capacity of entanglement-breaking channels,” preprint http://arxiv.org/abs/arXiv:1306.1586 (2013)] and Müller-Lennert et al. [“On quantum Rényi entropies: a new definition, some properties and several conjectures,” preprint http://arxiv.org/abs/arXiv:1306.3142v1 (2013)]. This new quantum divergence has already found applications in quantum information theory. Here we further investigate properties of this new quantum divergence. In particular, we show that sandwiched α-Rényi divergence satisfies the data processing inequality for all values of α > 1. Moreover we prove that α-Holevo information, a variant of Holevo information defined in terms of sandwiched α-Rényi divergence, is super-additive. Our results are based on Hölder's inequality, the Riesz-Thorin theorem and ideas from the theory of complex interpolation. We also employ Sion's minimax theorem

Vibhakti Divergence between Sanskrit and Hindi

Science.gov (United States)

Shukla, Preeti; Shukl, Devanand; Kulkarni, Amba

Translation divergence at various levels between languages arises due to the different conventions followed by different languages for coding the information of grammatical relations. Though Sanskrit and Hindi belong to the same Indo-Aryan family and structurally as well as lexically Hindi inherits a lot from Sanskrit, yet divergences are observed at the level of function words such as vibhaktis. Pāṇini in his Aṣṭādhyāyī has assigned a default vibhakti to kārakas alongwith many scopes for exceptions. He handles these exceptions either by imposing a new kāraka role or by assigning a special vibhakti. However, these methods are not acceptable in Hindi in toto. Based on the nature of deviation, we propose seven cases of divergences in this paper.

Lexicographic presentation of grammatical divergence in Sesotho ...

African Journals Online (AJOL)

Relying on existing insights from the field of theoretical lexicography this article gives an innovative application to the relation of divergence by introducing the notion of grammatical divergence. In bilingual dictionaries with English and Sesotho sa Leboa as language pair lexicographers are confronted with a real challenge ...

Variational divergence in wave scattering theory with Kirchhoffean trial functions

Science.gov (United States)

Bird, J. F.

1986-01-01

In a recent study of variational improvement of the Kirchhoff approximation for electromagnetic scattering by rough surfaces, a key ingredient in the variational principle was found to diverge for important configurations (e.g., backscatter) if the polarization had any vertical component. The cause and a cure of this divergence are discussed here. The divergence is demonstrated to occur for arbitrary perfectly conducting scatterers and its universal characterstics are determined, by means of a general divergence criterion that is derived. A variational cure for the divergence is prescribed, and it is tested successfully on a standard scattering model.

Does niche divergence accompany allopatric divergence in Aphelocoma jays as predicted under ecological speciation? Insights from tests with niche models.

Science.gov (United States)

McCormack, John E; Zellmer, Amanda J; Knowles, L Lacey

2010-05-01

The role of ecology in the origin of species has been the subject of long-standing interest to evolutionary biologists. New sources of spatially explicit ecological data allow for large-scale tests of whether speciation is associated with niche divergence or whether closely related species tend to be similar ecologically (niche conservatism). Because of the confounding effects of spatial autocorrelation of environmental variables, we generate null expectations for niche divergence for both an ecological-niche modeling and a multivariate approach to address the question: do allopatrically distributed taxa occupy similar niches? In a classic system for the study of niche evolution--the Aphelocoma jays--we show that there is little evidence for niche divergence among Mexican Jay (A. ultramarina) lineages in the process of speciation, contrary to previous results. In contrast, Aphelocoma species that exist in partial sympatry in some regions show evidence for niche divergence. Our approach is widely applicable to the many cases of allopatric lineages in the beginning stages of speciation. These results do not support an ecological speciation model for Mexican Jay lineages because, in most cases, the allopatric environments they occupy are not significantly more divergent than expected under a null model.

Estimating Divergence Time and Ancestral Effective Population Size of Bornean and Sumatran Orangutan Subspecies Using a Coalescent Hidden Markov Model

DEFF Research Database (Denmark)

Mailund, Thomas; Dutheil, Julien; Hobolth, Asger

2011-01-01

event has occurred to split them apart. The size of these segments of constant divergence depends on the recombination rate, but also on the speciation time, the effective population size of the ancestral population, as well as demographic effects and selection. Thus, inference of these parameters may......, and the ancestral effective population size. The model is efficient enough to allow inference on whole-genome data sets. We first investigate the power and consistency of the model with coalescent simulations and then apply it to the whole-genome sequences of the two orangutan sub-species, Bornean (P. p. pygmaeus......) and Sumatran (P. p. abelii) orangutans from the Orangutan Genome Project. We estimate the speciation time between the two sub-species to be thousand years ago and the effective population size of the ancestral orangutan species to be , consistent with recent results based on smaller data sets. We also report...

Beam Angular Divergence Effects in Ion Implantation

International Nuclear Information System (INIS)

Horsky, T. N.; Hahto, S. K.; Bilbrough, D. G.; Jacobson, D. C.; Krull, W. A.; Goldberg, R. D.; Current, M. I.; Hamamoto, N.; Umisedo, S.

2008-01-01

An important difference between monomer ion beams and heavy molecular beams is a significant reduction in beam angular divergence and increased on-wafer angular accuracy for molecular beams. This advantage in beam quality stems from a reduction in space-charge effects within the beam. Such improved angular accuracy has been shown to have a significant impact on the quality and yield of transistor devices [1,12]. In this study, B 18 H x + beam current and angular divergence data collected on a hybrid scanned beam line that magnetically scans the beam across the wafer is presented. Angular divergence is kept below 0.5 deg from an effective boron energy of 200 eV to 3000 eV. Under these conditions, the beam current is shown analytically to be limited by space charge below about 1 keV, but by the matching of the beam emittance to the acceptance of the beam line above 1 keV. In addition, results of a beam transport model which includes variable space charge compensation are presented, in which a drift mode B 18 H x + beam is compared to an otherwise identical boron beam after deceleration. Deceleration is shown to introduce significant space-charge blow up resulting in a large on-wafer angular divergence. The divergence effects introduced by wafer charging are also discussed.

Rapid divergence and convergence of life-history in experimentally evolved Drosophila melanogaster.

Science.gov (United States)

Burke, Molly K; Barter, Thomas T; Cabral, Larry G; Kezos, James N; Phillips, Mark A; Rutledge, Grant A; Phung, Kevin H; Chen, Richard H; Nguyen, Huy D; Mueller, Laurence D; Rose, Michael R

2016-09-01

Laboratory selection experiments are alluring in their simplicity, power, and ability to inform us about how evolution works. A longstanding challenge facing evolution experiments with metazoans is that significant generational turnover takes a long time. In this work, we present data from a unique system of experimentally evolved laboratory populations of Drosophila melanogaster that have experienced three distinct life-history selection regimes. The goal of our study was to determine how quickly populations of a certain selection regime diverge phenotypically from their ancestors, and how quickly they converge with independently derived populations that share a selection regime. Our results indicate that phenotypic divergence from an ancestral population occurs rapidly, within dozens of generations, regardless of that population's evolutionary history. Similarly, populations sharing a selection treatment converge on common phenotypes in this same time frame, regardless of selection pressures those populations may have experienced in the past. These patterns of convergence and divergence emerged much faster than expected, suggesting that intermediate evolutionary history has transient effects in this system. The results we draw from this system are applicable to other experimental evolution projects, and suggest that many relevant questions can be sufficiently tested on shorter timescales than previously thought. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

Active learning for noisy oracle via density power divergence.

Science.gov (United States)

Sogawa, Yasuhiro; Ueno, Tsuyoshi; Kawahara, Yoshinobu; Washio, Takashi

2013-10-01

The accuracy of active learning is critically influenced by the existence of noisy labels given by a noisy oracle. In this paper, we propose a novel pool-based active learning framework through robust measures based on density power divergence. By minimizing density power divergence, such as β-divergence and γ-divergence, one can estimate the model accurately even under the existence of noisy labels within data. Accordingly, we develop query selecting measures for pool-based active learning using these divergences. In addition, we propose an evaluation scheme for these measures based on asymptotic statistical analyses, which enables us to perform active learning by evaluating an estimation error directly. Experiments with benchmark datasets and real-world image datasets show that our active learning scheme performs better than several baseline methods. Copyright © 2013 Elsevier Ltd. All rights reserved.

Decoding divergent series in nonparaxial optics.

Science.gov (United States)

Borghi, Riccardo; Gori, Franco; Guattari, Giorgio; Santarsiero, Massimo

2011-03-15

A theoretical analysis aimed at investigating the divergent character of perturbative series involved in the study of free-space nonparaxial propagation of vectorial optical beams is proposed. Our analysis predicts a factorial divergence for such series and provides a theoretical framework within which the results of recently published numerical experiments concerning nonparaxial propagation of vectorial Gaussian beams find a meaningful interpretation in terms of the decoding operated on such series by the Weniger transformation.

Salivary gland proteome analysis reveals modulation of anopheline unique proteins in insensitive acetylcholinesterase resistant Anopheles gambiae mosquitoes.

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Sylvie Cornelie

Full Text Available Insensitive acetylcholinesterase resistance due to a mutation in the acetylcholinesterase (ace encoding ace-1 gene confers cross-resistance to organophosphate and carbamate insecticides in Anopheles gambiae populations from Central and West Africa. This mutation is associated with a strong genetic cost revealed through alterations of some life history traits but little is known about the physiological and behavioural changes in insects bearing the ace-1(R allele. Comparative analysis of the salivary gland contents between An. gambiae susceptible and ace-1(R resistant strains was carried out to charaterize factors that could be involved in modifications of blood meal process, trophic behaviour or pathogen interaction in the insecticide-resistant mosquitoes. Differential analysis of the salivary gland protein profiles revealed differences in abundance for several proteins, two of them showing major differences between the two strains. These two proteins identified as saglin and TRIO are salivary gland-1 related proteins, a family unique to anopheline mosquitoes, one of them playing a crucial role in salivary gland invasion by Plasmodium falciparum sporozoites. Differential expression of two other proteins previously identified in the Anopheles sialome was also observed. The differentially regulated proteins are involved in pathogen invasion, blood feeding process, and protection against oxidation, relevant steps in the outcome of malaria infection. Further functional studies and insect behaviour experiments would confirm the impact of the modification of the sialome composition on blood feeding and pathogen transmission abilities of the resistant mosquitoes. The data supports the hypothesis of alterations linked to insecticide resistance in the biology of the primary vector of human malaria in Africa.

The relation between gray matter morphology and divergent thinking in adolescents and young adults.

Directory of Open Access Journals (Sweden)

Janna Cousijn

Full Text Available Adolescence and early adulthood are developmental time periods during which creative cognition is highly important for adapting to environmental changes. Divergent thinking, which refers to generating novel and useful solutions to open-ended problems, has often been used as a measure of creative cognition. The first goal of this structural neuroimaging study was to elucidate the relationship between gray matter morphology and performance in the verbal (AUT; alternative uses task and visuo-spatial (CAT; creative ability test domain of divergent thinking in adolescents and young adults. The second goal was to test if gray matter morphology is related to brain activity during AUT performance. Neural and behavioral data were combined from a cross-sectional study including 25 adolescents aged 15-17 and 20 young adults aged 25-30. Brain-behavior relationships were assessed without a priori location assumptions and within areas that were activated during an AUT-scanner task. Gray matter volume and cortical thickness were not significantly associated with verbal divergent thinking. However, visuo-spatial divergent thinking (CAT originality and fluency was positively associated with cortical thickness of the right middle temporal gyrus and left brain areas including the superior frontal gyrus and various occipital, parietal, and temporal areas, independently of age. AUT brain activity was not associated with cortical thickness. The results support an important role of a widespread brain network involved in flexible visuo-spatial divergent thinking, providing evidence for a relation between cortical thickness and visuo-spatial divergent thinking in adolescents and young adults. However, studies including visuo-spatial divergent thinking tasks in the scanner are warranted.

Phenotypic Divergence in the Reproductive Traits of Marbled ...

African Journals Online (AJOL)

Overall, the results indicated some level of phenotypic divergence of the fish ... divergence cannot be partitioned between fishing mortality, genetic .... female fish was estimated from the egg counts ..... that greatly improved the quality of the.

Taming infrared divergences in the effective potential

Energy Technology Data Exchange (ETDEWEB)

Elias-Miro, J. [IFAE, Univ. Autonoma de Barcelona (Spain); Universitat Autonoma de Barcelona (Spain). Dept. de Fisica; Espinosa, J.R. [IFAE, Univ. Autonoma de Barcelona (Spain); ICREA, Institucio Catalana de Recerca i Estudis Avancats, Barcelona (Spain); Konstandin, T. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2014-06-15

The Higgs effective potential in the Standard Model (SM), calculated perturbatively, generically suffers from infrared (IR) divergences when the (field-dependent) tree-level mass of the Goldstone bosons goes to zero. Such divergences can affect both the potential and its first derivative and become worse with increasing loop order. In this paper we show that these IR divergences are spurious, we perform a simple resummation of all IR-problematic terms known (up to three loops) and explain how to extend the resummation to cure all such divergences to any order. The method is of general applicability and would work in scenarios other than the SM. Our discussion has some bearing on a scenario recently proposed as a mechanism for gauge mediation of scale breaking in the ultraviolet, in which it is claimed that the low-energy Higgs potential is non-standard. We argue that all non-decoupling effects from the heavy sector can be absorbed in the renormalization of low-energy parameters leading to a SM-like effective theory.

Taming infrared divergences in the effective potential

International Nuclear Information System (INIS)

Elias-Miro, J.; Konstandin, T.

2014-06-01

The Higgs effective potential in the Standard Model (SM), calculated perturbatively, generically suffers from infrared (IR) divergences when the (field-dependent) tree-level mass of the Goldstone bosons goes to zero. Such divergences can affect both the potential and its first derivative and become worse with increasing loop order. In this paper we show that these IR divergences are spurious, we perform a simple resummation of all IR-problematic terms known (up to three loops) and explain how to extend the resummation to cure all such divergences to any order. The method is of general applicability and would work in scenarios other than the SM. Our discussion has some bearing on a scenario recently proposed as a mechanism for gauge mediation of scale breaking in the ultraviolet, in which it is claimed that the low-energy Higgs potential is non-standard. We argue that all non-decoupling effects from the heavy sector can be absorbed in the renormalization of low-energy parameters leading to a SM-like effective theory.

Exact cancellation of quadratic divergences in top condensation models

International Nuclear Information System (INIS)

Blumhofer, A.

1995-01-01

We discuss the hierarchy problem and the corresponding quadratic divergences in the top mode Standard Model. Quadratic divergences appear at each order 1/N c since fermionic and bosonic contributions are of different order 1/N c . It is shown that the full dynamical system to all orders in 1/N c admits a solution, where the sum of all quadratic divergent contributions disappears. ((orig.))

World health inequality: convergence, divergence, and development.

Science.gov (United States)

Clark, Rob

2011-02-01

Recent studies characterize the last half of the twentieth century as an era of cross-national health convergence, with some attributing welfare gains in the developing world to economic growth. In this study, I examine the extent to which welfare outcomes have actually converged and the extent to which economic development is responsible for the observed trends. Drawing from estimates covering 195 nations during the 1955-2005 period, I find that life expectancy averages converged during this time, but that infant mortality rates continuously diverged. I develop a narrative that implicates economic development in these contrasting trends, suggesting that health outcomes follow a "welfare Kuznets curve." Among poor countries, economic development improves life expectancy more than it reduces infant mortality, whereas the situation is reversed among wealthier nations. In this way, development has contributed to both convergence in life expectancy and divergence in infant mortality. Drawing from 674 observations across 163 countries during the 1980-2005 period, I find that the positive effect of GDP PC on life expectancy attenuates at higher levels of development, while the negative effect of GDP PC on infant mortality grows stronger. Copyright © 2010 Elsevier Ltd. All rights reserved.

Total Bregman Divergence and its Applications to Shape Retrieval.

Science.gov (United States)

Liu, Meizhu; Vemuri, Baba C; Amari, Shun-Ichi; Nielsen, Frank

2010-01-01

Shape database search is ubiquitous in the world of biometric systems, CAD systems etc. Shape data in these domains is experiencing an explosive growth and usually requires search of whole shape databases to retrieve the best matches with accuracy and efficiency for a variety of tasks. In this paper, we present a novel divergence measure between any two given points in [Formula: see text] or two distribution functions. This divergence measures the orthogonal distance between the tangent to the convex function (used in the definition of the divergence) at one of its input arguments and its second argument. This is in contrast to the ordinate distance taken in the usual definition of the Bregman class of divergences [4]. We use this orthogonal distance to redefine the Bregman class of divergences and develop a new theory for estimating the center of a set of vectors as well as probability distribution functions. The new class of divergences are dubbed the total Bregman divergence (TBD). We present the l 1 -norm based TBD center that is dubbed the t-center which is then used as a cluster center of a class of shapes The t-center is weighted mean and this weight is small for noise and outliers. We present a shape retrieval scheme using TBD and the t-center for representing the classes of shapes from the MPEG-7 database and compare the results with other state-of-the-art methods in literature.

Vorticity and divergence in the high-latitude upper thermosphere

International Nuclear Information System (INIS)

Thayer, J.P.; Killeen, T.L.

1991-01-01

Measurements made from the Dynamics Explorer-2 satellite in November 1981 through January 1982 and November 1982 through January 1983 have been analyzed to determine the divergence and vertical component of vorticity of the high-latitude neutral wind field in the upper thermosphere for quiet (kp≤6) geomagnetic conditions and for both northern (winter) and southern (summer) hemispheres in the polar thermosphere and provides insight into the relative strengths of the different sources of momentum and energy responsible for driving the winds. The principal findings from this work include the following: The mean neutral wind pattern is dominated by rotational flow rather than by divergent flow, with a typical vorticity: divergence ratio of ∼ 2:1 for active conditions and ∼ 4:1 for quiet conditions. Comparison of the divergence and vorticity patterns for quiet and active conditions indicates that the divergent component of the neutral flow intensifies more significantly with increasing geomagnetic activity than does the rotational component

A Separation between Divergence and Holevo Information for Ensembles

OpenAIRE

Jain, Rahul; Nayak, Ashwin; Su, Yi

2007-01-01

The notion of divergence information of an ensemble of probability distributions was introduced by Jain, Radhakrishnan, and Sen in the context of the ``substate theorem''. Since then, divergence has been recognized as a more natural measure of information in several situations in quantum and classical communication. We construct ensembles of probability distributions for which divergence information may be significantly smaller than the more standard Holevo information. As a result, we establ...

Differential divergences of obligately insect-pathogenic Entomophthora species from fly and aphid hosts.

Science.gov (United States)

Jensen, Annette Bruun; Eilenberg, Jørgen; López Lastra, Claudia

2009-11-01

Three DNA regions (ITS 1, LSU rRNA and GPD) of isolates from the insect-pathogenic fungus genus Entomophthora originating from different fly (Diptera) and aphid (Hemiptera) host taxa were sequenced. The results documented a large genetic diversity among the fly-pathogenic Entomophthora and only minor differences among aphid-pathogenic Entomophthora. The evolutionary time of divergence of the fly and the aphid host taxa included cannot account for this difference. The host-driven divergence of Entomophthora, therefore, has been much greater in flies than in aphids. Host-range differences or a recent host shift to aphid are possible explanations.

Evidence of multiple divergent mitochondrial lineages within the ...

African Journals Online (AJOL)

On this basis, the mitochondrial cytochrome c oxidase subunit 1 (COI) was used to reconstruct the phylogeny of Bicoxidens and reveal divergent lineages within the genus. Maximum likelihood and Bayesian inference analyses recovered a paraphyletic Bicoxidens phylogram with divergent lineages present in three species ...

Diverging expectations in buyer-seller relationships

DEFF Research Database (Denmark)

Andersen, Poul Houman; Christensen, Poul Rind; Damgaard, Torben

2009-01-01

Many firms assume that outsourcing partnerships may allow them to strengthen their overall competitiveness. Lured by its intuitive appeal, several enter into such partnerships, only to realize that they represent a marginal rather than a magical solution to their quest for increasing market...... performance. We explore the proposed impact of diverging relationship norms on relationship expectations using data from an ongoing field study of Danish buyers and Chinese suppliers. We link these diverging expectations to the business practices of Danish buyers and Chinese and their institutional contexts...

Divergence of gene body DNA methylation and evolution of plant duplicate genes.

Directory of Open Access Journals (Sweden)

Jun Wang

Full Text Available It has been shown that gene body DNA methylation is associated with gene expression. However, whether and how deviation of gene body DNA methylation between duplicate genes can influence their divergence remains largely unexplored. Here, we aim to elucidate the potential role of gene body DNA methylation in the fate of duplicate genes. We identified paralogous gene pairs from Arabidopsis and rice (Oryza sativa ssp. japonica genomes and reprocessed their single-base resolution methylome data. We show that methylation in paralogous genes nonlinearly correlates with several gene properties including exon number/gene length, expression level and mutation rate. Further, we demonstrated that divergence of methylation level and pattern in paralogs indeed positively correlate with their sequence and expression divergences. This result held even after controlling for other confounding factors known to influence the divergence of paralogs. We observed that methylation level divergence might be more relevant to the expression divergence of paralogs than methylation pattern divergence. Finally, we explored the mechanisms that might give rise to the divergence of gene body methylation in paralogs. We found that exonic methylation divergence more closely correlates with expression divergence than intronic methylation divergence. We show that genomic environments (e.g., flanked by transposable elements and repetitive sequences of paralogs generated by various duplication mechanisms are associated with the methylation divergence of paralogs. Overall, our results suggest that the changes in gene body DNA methylation could provide another avenue for duplicate genes to develop differential expression patterns and undergo different evolutionary fates in plant genomes.

Phylogenetic heritability of geographic range size in haematophagous ectoparasites: time of divergence and variation among continents.

Science.gov (United States)

Krasnov, Boris R; Shenbrot, Georgy I; van der Mescht, Luther; Warburton, Elizabeth M; Khokhlova, Irina S

2018-04-12

To understand existence, patterns and mechanisms behind phylogenetic heritability in the geographic range size (GRS) of parasites, we measured phylogenetic signal (PS) in the sizes of both regional (within a region) and continental (within a continent) geographic ranges of fleas in five regions. We asked whether (a) GRS is phylogenetically heritable and (b) the manifestation of PS varies between regions. We also asked whether geographic variation in PS reflects the effects of the environment's spatiotemporal stability (e.g. glaciation disrupting geographic ranges) or is associated with time since divergence (accumulation differences among species over time). Support for the former hypothesis would be indicated by stronger PS in southern than in northern regions, whereas support for the latter hypothesis would be shown by stronger PS in regions with a large proportion of species belonging to the derived lineages than in regions with a large proportion of species belonging to the basal lineages. We detected significant PS in both regional and continental GRSs of fleas from Canada and in continental GRS of fleas from Mongolia. No PS was found in the GRS of fleas from Australia and Southern Africa. Venezuelan fleas demonstrated significant PS in regional GRS only. Local Indicators of Phylogenetic Association detected significant local positive autocorrelations of GRS in some clades even in regions in which PS has not been detected across the entire phylogeny. This was mainly characteristic of younger taxa.

Impact of urothelial carcinoma with divergent differentiation on tumor stage

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S Chalise

2016-03-01

Full Text Available Background: Urinary bladder cancer is classified as urothelial or non-urothelial. Ninenty percent of bladder cancer are urothelial and has propensity for divergent differentiation. Squamous differentiation is associated with unfavourable prognostic features. The aim of this study is to determine the significance of urothelial carcinoma with divergent differentiation in relation to tumor stage and lymphovascular as well as perineural invasion in radical cystectomy and partial cystectomy specimen.Materials and methods: This prospective study was done among 51 patients who underwent radical cystectomy or partial cystectomy at Bhaktapur Cancer Hospital from 1st August 2013 to 31st December 2015. Received specimen was grossed following standard protocol and histopathological evaluation was done in relation to tumor type, depth of invasion, Lymphovascular and perineural invasion.Results: Pure urothelial carcinoma comprises 47.1% of cases. Among the divergent differentiation, urothelial carcinoma with squamous differentiation was the commonest one (39.2% followed by glandular differentiation (5.9%, sarcomatoid differentiation (3.9%, clear cell variant (2.0% and squamous along with sarcomatoid variant (2.0%. Statistical significant correlation was found between urothelial carcinoma with divergent differentiation and tumor stage (p<0.012. Statistically significant correlation was also found between urothelial carcinoma with divergent differentiation and lymphovascular invasion (p=0.012 as well as perineural invasion (p=0.037.Conclusion:  Most common divergent differentiation was squamous differentiation. Urothelial carcinoma with divergent differentiation was associated with higher stage and lymphovascular as well as perineural invasion. So it is mandatory to search for the divergent differentiation in urothelial carcinoma as this may be associated with unfavourable prognosis.

Sufficient Statistics for Divergence and the Probability of Misclassification

Science.gov (United States)

Quirein, J.

1972-01-01

One particular aspect is considered of the feature selection problem which results from the transformation x=Bz, where B is a k by n matrix of rank k and k is or = to n. It is shown that in general, such a transformation results in a loss of information. In terms of the divergence, this is equivalent to the fact that the average divergence computed using the variable x is less than or equal to the average divergence computed using the variable z. A loss of information in terms of the probability of misclassification is shown to be equivalent to the fact that the probability of misclassification computed using variable x is greater than or equal to the probability of misclassification computed using variable z. First, the necessary facts relating k-dimensional and n-dimensional integrals are derived. Then the mentioned results about the divergence and probability of misclassification are derived. Finally it is shown that if no information is lost (in x = Bz) as measured by the divergence, then no information is lost as measured by the probability of misclassification.

Segmenting the human genome based on states of neutral genetic divergence.

Science.gov (United States)

Kuruppumullage Don, Prabhani; Ananda, Guruprasad; Chiaromonte, Francesca; Makova, Kateryna D

2013-09-03

Many studies have demonstrated that divergence levels generated by different mutation types vary and covary across the human genome. To improve our still-incomplete understanding of the mechanistic basis of this phenomenon, we analyze several mutation types simultaneously, anchoring their variation to specific regions of the genome. Using hidden Markov models on insertion, deletion, nucleotide substitution, and microsatellite divergence estimates inferred from human-orangutan alignments of neutrally evolving genomic sequences, we segment the human genome into regions corresponding to different divergence states--each uniquely characterized by specific combinations of divergence levels. We then parsed the mutagenic contributions of various biochemical processes associating divergence states with a broad range of genomic landscape features. We find that high divergence states inhabit guanine- and cytosine (GC)-rich, highly recombining subtelomeric regions; low divergence states cover inner parts of autosomes; chromosome X forms its own state with lowest divergence; and a state of elevated microsatellite mutability is interspersed across the genome. These general trends are mirrored in human diversity data from the 1000 Genomes Project, and departures from them highlight the evolutionary history of primate chromosomes. We also find that genes and noncoding functional marks [annotations from the Encyclopedia of DNA Elements (ENCODE)] are concentrated in high divergence states. Our results provide a powerful tool for biomedical data analysis: segmentations can be used to screen personal genome variants--including those associated with cancer and other diseases--and to improve computational predictions of noncoding functional elements.

Coherence and Divergence of Megatrends in Science and Engineering

Science.gov (United States)

Roco, M. C.

2002-04-01

Scientific discoveries and technological innovations are at the core of human endeavor, and it is estimated that their role will only increase in time. Such advancements evolve in coherence, with areas of confluence and temporary divergences, which bring synergism and that stimulate further developments following in average an exponential growth. Six increasingly interconnected megatrends are perceived as dominating the scene for the next decades: (a) information and computing, (b) nanoscale science and engineering (S&E), (c) biology and bio-environmental approaches, (d) medical sciences and enhancing human physical capabilities, (e) cognitive sciences and enhancing intellectual abilities, and (f) collective behavior and system approach. This paper presents a perspective on the process of identification, planning and program implementation of S&E megatrends, with illustration for the US research initiative on nanoscale science, engineering, and technology. The interplay between coherence and divergence, leading to unifying science and converging technologies, does not develop only among simultaneous scientific trends but also along time and across geopolitical boundaries. There is no single way of development of S&E, and here is the role of taking visionary measures. Societal implication scientists need to be involved from the conceptual phase of a program responding to a S&E megatrend.

Coherence and Divergence of Megatrends in Science and Engineering

International Nuclear Information System (INIS)

Roco, M.C.

2002-01-01

Scientific discoveries and technological innovations are at the core of human endeavor, and it is estimated that their role will only increase in time. Such advancements evolve in coherence, with areas of confluence and temporary divergences, which bring synergism and that stimulate further developments following in average an exponential growth. Six increasingly interconnected megatrends are perceived as dominating the scene for the next decades: (a) information and computing, (b) nanoscale science and engineering (S and E), (c) biology and bio-environmental approaches, (d) medical sciences and enhancing human physical capabilities, (e) cognitive sciences and enhancing intellectual abilities, and (f) collective behavior and system approach.This paper presents a perspective on the process of identification, planning and program implementation of S and E megatrends, with illustration for the US research initiative on nanoscale science, engineering, and technology. The interplay between coherence and divergence, leading to unifying science and converging technologies, does not develop only among simultaneous scientific trends but also along time and across geopolitical boundaries. There is no single way of development of S and E, and here is the role of taking visionary measures. Societal implication scientists need to be involved from the conceptual phase of a program responding to a S and E megatrend

GENDER-BASED DIFFERENCES IN SCHOOL-AGED CHILDREN’S DIVERGENT THINKING

Directory of Open Access Journals (Sweden)

Leah Roue

2014-12-01

Full Text Available This study examines whether the shortage of females in science and engineering is linked to possible gender-based differences in school-aged children’s divergent thinking. Divergent thinking is a direct measure of creativity and an important characteristic in science and engineering. A survey instrument designed to measure divergent thinking was administered to 8th and 11th graders in a mid-western United States school district. Results showed that there were no difference between girls and boys on the three measures of divergent thinking: fluency, flexibility, and originality. These results indicate little reason as to why participation in science and engineering is male dominated, and support the notion that additional exposure to science and engineering through divergent-thinking activities will provide girls with the self-knowledge that they are capable of solving open-ended problems and engineering tasks.

New classification of natural breeding habitats for Neotropical anophelines in the Yanomami Indian Reserve, Amazon Region, Brazil and a new larval sampling methodology.

Science.gov (United States)

Sánchez-Ribas, Jordi; Oliveira-Ferreira, Joseli; Rosa-Freitas, Maria Goreti; Trilla, Lluís; Silva-do-Nascimento, Teresa Fernandes

2015-09-01

Here we present the first in a series of articles about the ecology of immature stages of anophelines in the Brazilian Yanomami area. We propose a new larval habitat classification and a new larval sampling methodology. We also report some preliminary results illustrating the applicability of the methodology based on data collected in the Brazilian Amazon rainforest in a longitudinal study of two remote Yanomami communities, Parafuri and Toototobi. In these areas, we mapped and classified 112 natural breeding habitats located in low-order river systems based on their association with river flood pulses, seasonality and exposure to sun. Our classification rendered seven types of larval habitats: lakes associated with the river, which are subdivided into oxbow lakes and nonoxbow lakes, flooded areas associated with the river, flooded areas not associated with the river, rainfall pools, small forest streams, medium forest streams and rivers. The methodology for larval sampling was based on the accurate quantification of the effective breeding area, taking into account the area of the perimeter and subtypes of microenvironments present per larval habitat type using a laser range finder and a small portable inflatable boat. The new classification and new sampling methodology proposed herein may be useful in vector control programs.

New classification of natural breeding habitats for Neotropical anophelines in the Yanomami Indian Reserve, Amazon Region, Brazil and a new larval sampling methodology

Directory of Open Access Journals (Sweden)

Jordi Sánchez-Ribas

2015-09-01

Full Text Available Here we present the first in a series of articles about the ecology of immature stages of anophelines in the Brazilian Yanomami area. We propose a new larval habitat classification and a new larval sampling methodology. We also report some preliminary results illustrating the applicability of the methodology based on data collected in the Brazilian Amazon rainforest in a longitudinal study of two remote Yanomami communities, Parafuri and Toototobi. In these areas, we mapped and classified 112 natural breeding habitats located in low-order river systems based on their association with river flood pulses, seasonality and exposure to sun. Our classification rendered seven types of larval habitats: lakes associated with the river, which are subdivided into oxbow lakes and nonoxbow lakes, flooded areas associated with the river, flooded areas not associated with the river, rainfall pools, small forest streams, medium forest streams and rivers. The methodology for larval sampling was based on the accurate quantification of the effective breeding area, taking into account the area of the perimeter and subtypes of microenvironments present per larval habitat type using a laser range finder and a small portable inflatable boat. The new classification and new sampling methodology proposed herein may be useful in vector control programs.

Frequencies of digits, divergence points, and Schmidt games

International Nuclear Information System (INIS)

Olsen, L.

2009-01-01

Sets of divergence points, i.e. numbers x (or tuples of numbers) for which the limiting frequency of a given string of N-adic digits of x fails to exist, have recently attracted huge interest in the literature. In this paper we consider sets of simultaneous divergence points, i.e. numbers x (or tuples of numbers) for which the limiting frequencies of all strings of N-adic digits of x fail to exist. We show that many natural sets of simultaneous divergence points are (α, β)-wining sets in the sense of the Schmidt game. As an application we obtain lower bounds for the Hausdorff dimension of these sets.

How diking affects the longer-term structure and evolution of divergent plate boundaries

KAUST Repository

Trippanera, Daniele; Acocella, Valerio; Ruch, Joel; Rivalta, Eleonora

2015-01-01

Recurrent diking episodes along divergent plate boundaries, as at Dabbahu (2005, Afar) or at Bardarbunga (2014, Iceland) , highlight the possibility to have m-wide opening in a short time (days to weeks). This suggests a prominent role of magma

The direct Flow parametric Proof of Gauss' Divergence Theorem revisited

DEFF Research Database (Denmark)

Markvorsen, Steen

The standard proof of the divergence theorem in undergraduate calculus courses covers the theorem for static domains between two graph surfaces. We show that within first year undergraduate curriculum, the flow proof of the dynamic version of the divergence theorem - which is usually considered...... we apply the key instrumental concepts and verify the various steps towards this alternative proof of the divergence theorem....

Laser fusion target illumination optimization with consideration of the beam divergence

International Nuclear Information System (INIS)

Grzanna, J.; Schoennagel, H.

1982-09-01

Using a focusing system with a great focal length it is demonstrated that the radiation divergence considerably influences the illumination optimization. If the channel beam is composed of several single beams, there are two optimum illumination variants: the channel beam tangent and the single beam tangent illumination. Further, it is shown that the illumination channel distribution function can vary in the central region without any effect on the illumination uniformity. The deviation at the periphery is more critical. The most homogeneous illumination and favourable energy transfer would be obtained by low radiation divergence and optimum lateral and axial defocusing of the single beam imaging a suitable near-field intensity pattern on the target surface. It is emphasized that the estimation was made without considering the plasma parameters and the dynamic variation in time. (author)

Endemic infrared divergences in QED3 at finite temperature

International Nuclear Information System (INIS)

Lo, Pok Man; Swanson, Eric S.

2011-01-01

We demonstrate that massless QED in three dimensions contains endemic infrared divergences. It is argued that these divergences do not affect observables; furthermore, it is possible to choose a gauge that renders the theory finite.

Design of a divergence and alignment indicator

International Nuclear Information System (INIS)

Brenizer, J.S. Jr.; Raine, D.A.; Gao, J.; Chen, J.

1996-01-01

The divergence and alignment indicator (DAI) is an extension of the ASTM E803 L/D thermal neutron radiography L/D device that allows the user to determine both the beam centerline and the beam divergence. The DAI was made using aluminium plate and rods, and incorporated cadmium wire for contrast. Circular symmetry was utilized to simplify manufacture. The DAI was placed with the five posts against the film cassette or radioscopic imaging device in the physical center of the beam. The DAI was perpendicular to the selected beam radius when the front and back center Cd wire images overlap. The degree of misalignment was indicated by their image positions. After the DAI was aligned, analysis of the cadmium wire ''+'' image spacing yielded the beam divergence. The DAI was tested in a neutron beam which has an L/D of 30 but a small degree of divergence. The DAI was also imaged using an X-ray source. The point source predictions of Cd wire image locations showed good agreement with those measured from the X-ray radiograph. The neutron radiographic locations could be predicted using the point source equations, even though the neutron beam was a complex distributed source. (orig.)

Divergence with gene flow across a speciation continuum of Heliconius butterflies.

Science.gov (United States)

Supple, Megan A; Papa, Riccardo; Hines, Heather M; McMillan, W Owen; Counterman, Brian A

2015-09-24

A key to understanding the origins of species is determining the evolutionary processes that drive the patterns of genomic divergence during speciation. New genomic technologies enable the study of high-resolution genomic patterns of divergence across natural speciation continua, where taxa pairs with different levels of reproductive isolation can be used as proxies for different stages of speciation. Empirical studies of these speciation continua can provide valuable insights into how genomes diverge during speciation. We examine variation across a handful of genomic regions in parapatric and allopatric populations of Heliconius butterflies with varying levels of reproductive isolation. Genome sequences were mapped to 2.2-Mb of the H. erato genome, including 1-Mb across the red color pattern locus and multiple regions unlinked to color pattern variation. Phylogenetic analyses reveal a speciation continuum of pairs of hybridizing races and incipient species in the Heliconius erato clade. Comparisons of hybridizing pairs of divergently colored races and incipient species reveal that genomic divergence increases with ecological and reproductive isolation, not only across the locus responsible for adaptive variation in red wing coloration, but also at genomic regions unlinked to color pattern. We observe high levels of divergence between the incipient species H. erato and H. himera, suggesting that divergence may accumulate early in the speciation process. Comparisons of genomic divergence between the incipient species and allopatric races suggest that limited gene flow cannot account for the observed high levels of divergence between the incipient species. Our results provide a reconstruction of the speciation continuum across the H. erato clade and provide insights into the processes that drive genomic divergence during speciation, establishing the H. erato clade as a powerful framework for the study of speciation.

Performance analysis of alpha divergence in nonnegative matrix ...

African Journals Online (AJOL)

This is achieved by using a suitable cost function to determine the optimal factorization. Most work in this field has focused on the use of Euclidean and Kullback-Liebler (KL) divergence. This study looks into the use of α-divergence based non negative factorization in the context of single channel musical sound separation.

Hamiltonian mechanics and divergence-free fields

International Nuclear Information System (INIS)

Boozer, A.H.

1986-08-01

The field lines, or integral curves, of a divergence-free field in three dimensions are shown to be topologically equivalent to the trajectories of a Hamiltonian with two degrees of freedom. The consideration of fields that depend on a parameter allow the construction of a canonical perturbation theory which is valid even if the perturbation is large. If the parametric dependence of the magnetic, or the vorticity field is interpreted as time dependence, evolution equations are obtained which give Kelvin's theorem or the flux conservation theorem for ideal fluids and plasmas. The Hamiltonian methods prove especially useful for study of fields in which the field lines must be known throughout a volume of space

Multiloop divergences in the closed bosonic string theory

International Nuclear Information System (INIS)

Gava, E.; Iengo, R.; Jayaraman, T.; Ramachandran, R.

1985-12-01

We discuss the structure of the divergences in the multiloop vacuum diagrams for the closed bosonic strings in the framework of the Polyakov covariant formalism. We find, by an explicit computation, that all the divergences in the theory may be interpreted as due to tadpole diagrams in which the dilation goes into the vacuum. (author)

Species divergence and phylogenetic variation of ecophysiological traits in lianas and trees.

Science.gov (United States)

Rios, Rodrigo S; Salgado-Luarte, Cristian; Gianoli, Ernesto

2014-01-01

The climbing habit is an evolutionary key innovation in plants because it is associated with enhanced clade diversification. We tested whether patterns of species divergence and variation of three ecophysiological traits that are fundamental for plant adaptation to light environments (maximum photosynthetic rate [A(max)], dark respiration rate [R(d)], and specific leaf area [SLA]) are consistent with this key innovation. Using data reported from four tropical forests and three temperate forests, we compared phylogenetic distance among species as well as the evolutionary rate, phylogenetic distance and phylogenetic signal of those traits in lianas and trees. Estimates of evolutionary rates showed that R(d) evolved faster in lianas, while SLA evolved faster in trees. The mean phylogenetic distance was 1.2 times greater among liana species than among tree species. Likewise, estimates of phylogenetic distance indicated that lianas were less related than by chance alone (phylogenetic evenness across 63 species), and trees were more related than expected by chance (phylogenetic clustering across 71 species). Lianas showed evenness for R(d), while trees showed phylogenetic clustering for this trait. In contrast, for SLA, lianas exhibited phylogenetic clustering and trees showed phylogenetic evenness. Lianas and trees showed patterns of ecophysiological trait variation among species that were independent of phylogenetic relatedness. We found support for the expected pattern of greater species divergence in lianas, but did not find consistent patterns regarding ecophysiological trait evolution and divergence. R(d) followed the species-level pattern, i.e., greater divergence/evolution in lianas compared to trees, while the opposite occurred for SLA and no pattern was detected for A(max). R(d) may have driven lianas' divergence across forest environments, and might contribute to diversification in climber clades.

Concrete ensemble Kalman filters with rigorous catastrophic filter divergence.

Science.gov (United States)

Kelly, David; Majda, Andrew J; Tong, Xin T

2015-08-25

The ensemble Kalman filter and ensemble square root filters are data assimilation methods used to combine high-dimensional, nonlinear dynamical models with observed data. Ensemble methods are indispensable tools in science and engineering and have enjoyed great success in geophysical sciences, because they allow for computationally cheap low-ensemble-state approximation for extremely high-dimensional turbulent forecast models. From a theoretical perspective, the dynamical properties of these methods are poorly understood. One of the central mysteries is the numerical phenomenon known as catastrophic filter divergence, whereby ensemble-state estimates explode to machine infinity, despite the true state remaining in a bounded region. In this article we provide a breakthrough insight into the phenomenon, by introducing a simple and natural forecast model that transparently exhibits catastrophic filter divergence under all ensemble methods and a large set of initializations. For this model, catastrophic filter divergence is not an artifact of numerical instability, but rather a true dynamical property of the filter. The divergence is not only validated numerically but also proven rigorously. The model cleanly illustrates mechanisms that give rise to catastrophic divergence and confirms intuitive accounts of the phenomena given in past literature.

Activation Detection in fMRI Using Jeffrey Divergence

Science.gov (United States)

Seghouane, Abd-Krim

2009-12-01

A statistical test for detecting activated pixels in functional MRI (fMRI) data is proposed. For the derivation of this test, the fMRI time series measured at each voxel is modeled as the sum of a response signal which arises due to the experimentally controlled activation-baseline pattern, a nuisance component representing effects of no interest, and Gaussian white noise. The test is based on comparing the dimension of the voxels fMRI time series fitted data models with and without controlled activation-baseline pattern. The Jeffrey divergence is used for this comparison. The test has the advantage of not requiring a level of significance or a threshold to be provided.

Island biology and morphological divergence of the Skyros wall lizard Podarcis gaigeae: a combined role for local selection and genetic drift on color morph frequency divergence?

Directory of Open Access Journals (Sweden)

Runemark Anna

2010-09-01

Full Text Available Abstract Background Patterns of spatial variation in discrete phenotypic traits can be used to draw inferences about the adaptive significance of traits and evolutionary processes, especially when compared to patterns of neutral genetic variation. Population divergence in adaptive traits such as color morphs can be influenced by both local ecology and stochastic factors such as genetic drift or founder events. Here, we use quantitative color measurements of males and females of Skyros wall lizard, Podarcis gaigeae, to demonstrate that this species is polymorphic with respect to throat color, and the morphs form discrete phenotypic clusters with limited overlap between categories. We use divergence in throat color morph frequencies and compare that to neutral genetic variation to infer the evolutionary processes acting on islet- and mainland populations. Results Geographically close islet- and mainland populations of the Skyros wall lizard exhibit strong divergence in throat color morph frequencies. Population variation in throat color morph frequencies between islets was higher than that between mainland populations, and the effective population sizes on the islets were small (Ne:s ST for throat color morph frequencies fell within the neutral FST-distribution estimated from microsatellite markers, and genetic drift could thus not be rejected as an explanation for the pattern. Moreover, for both comparisons among mainland-mainland population pairs and between mainland-islet population pairs, morph frequency divergence was significantly correlated with neutral divergence, further pointing to some role for genetic drift in divergence also at the phenotypic level of throat color morphs. Conclusions Genetic drift could not be rejected as an explanation for the pattern of population divergence in morph frequencies. In spite of an expected stabilising selection, throat color frequencies diverged in the islet populations. These results suggest that

Wing patterning genes and coevolution of Müllerian mimicry in Heliconius butterflies: Support from phylogeography, cophylogeny, and divergence times.

Science.gov (United States)

Hoyal Cuthill, Jennifer F; Charleston, Michael

2015-12-01

Examples of long-term coevolution are rare among free-living organisms. Müllerian mimicry in Heliconius butterflies had been suggested as a key example of coevolution by early genetic studies. However, research over the last two decades has been dominated by the idea that the best-studied comimics, H. erato and H. melpomene, did not coevolve at all. Recently sequenced genes associated with wing color pattern phenotype offer a new opportunity to resolve this controversy. Here, we test the hypothesis of coevolution between H. erato and H. melpomene using Bayesian multilocus analysis of five color pattern genes and five neutral genetic markers. We first explore the extent of phylogenetic agreement versus conflict between the different genes. Coevolution is then tested against three aspects of the mimicry diversifications: phylogenetic branching patterns, divergence times, and, for the first time, phylogeographic histories. We show that all three lines of evidence are compatible with strict coevolution of the diverse mimicry wing patterns, contrary to some recent suggestions. Instead, these findings tally with a coevolutionary diversification driven primarily by the ecological force of Müllerian mimicry. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

Mitogenome sequencing reveals shallow evolutionary histories and recent divergence time between morphologically and ecologically distinct European whitefish (Coregonus spp.)

DEFF Research Database (Denmark)

Jacobsen, Magnus W.; Hansen, Michael Møller; Orlando, Ludovic

2012-01-01

colonized Denmark following the last glacial maximum, Bayesian Serial SimCoal analysis showed consistency with a scenario of long-term stability, resulting from a rapid initial sixfold population expansion. The findings illustrate the utility of mitogenome data for resolving recent intraspecific divergence...

Dike-induced contraction along oceanic and continental divergent plate boundaries

KAUST Repository

Trippanera, D.

2014-10-28

The axis of divergent plate boundaries shows extension fractures and normal faults at the surface. Here we present evidence of contraction along the axis of the oceanic ridge of Iceland and the continental Main Ethiopian Rift. Contraction is found at the base of the tilted hanging wall of dilational normal faults, balancing part of their extension. Our experiments suggest that these structures result from dike emplacement. Multiple dike injection induces subsidence above and uplift to the sides of the dikes; the transition in between is accommodated by reverse faults and subsequent peripheral inward dipping normal faults. Our results suggest that contraction is a direct product of magma emplacement along divergent plate boundaries, at various scales, marking a precise evolutionary stage and initiating part of the extensional structures (extension fractures and normal faults). Key Points Contraction along divergent plate boundaries results from dike emplacementContraction generates extensional structures along divergent plate boundariesSurface deformation along divergent plate boundaries may be magma induced

Dike-induced contraction along oceanic and continental divergent plate boundaries

KAUST Repository

Trippanera, D.; Acocella, V.; Ruch, Joel

2014-01-01

The axis of divergent plate boundaries shows extension fractures and normal faults at the surface. Here we present evidence of contraction along the axis of the oceanic ridge of Iceland and the continental Main Ethiopian Rift. Contraction is found at the base of the tilted hanging wall of dilational normal faults, balancing part of their extension. Our experiments suggest that these structures result from dike emplacement. Multiple dike injection induces subsidence above and uplift to the sides of the dikes; the transition in between is accommodated by reverse faults and subsequent peripheral inward dipping normal faults. Our results suggest that contraction is a direct product of magma emplacement along divergent plate boundaries, at various scales, marking a precise evolutionary stage and initiating part of the extensional structures (extension fractures and normal faults). Key Points Contraction along divergent plate boundaries results from dike emplacementContraction generates extensional structures along divergent plate boundariesSurface deformation along divergent plate boundaries may be magma induced

Genetic divergence of tomato subsamples

Directory of Open Access Journals (Sweden)

André Pugnal Mattedi

2014-02-01

Full Text Available Understanding the genetic variability of a species is crucial for the progress of a genetic breeding program and requires characterization and evaluation of germplasm. This study aimed to characterize and evaluate 101 tomato subsamples of the Salad group (fresh market and two commercial controls, one of the Salad group (cv. Fanny and another of the Santa Cruz group (cv. Santa Clara. Four experiments were conducted in a randomized block design with three replications and five plants per plot. The joint analysis of variance was performed and characteristics with significant complex interaction between control and experiment were excluded. Subsequently, the multicollinearity diagnostic test was carried out and characteristics that contributed to severe multicollinearity were excluded. The relative importance of each characteristics for genetic divergence was calculated by the Singh's method (Singh, 1981, and the less important ones were excluded according to Garcia (1998. Results showed large genetic divergence among the subsamples for morphological, agronomic and organoleptic characteristics, indicating potential for genetic improvement. The characteristics total soluble solids, mean number of good fruits per plant, endocarp thickness, mean mass of marketable fruit per plant, total acidity, mean number of unmarketable fruit per plant, internode diameter, internode length, main stem thickness and leaf width contributed little to the genetic divergence between the subsamples and may be excluded in future studies.

Natural variation of the RICE FLOWERING LOCUS T 1 contributes to flowering time divergence in rice.

Directory of Open Access Journals (Sweden)

Eri Ogiso-Tanaka

Full Text Available In rice (Oryza sativa L., there is a diversity in flowering time that is strictly genetically regulated. Some indica cultivars show extremely late flowering under long-day conditions, but little is known about the gene(s involved. Here, we demonstrate that functional defects in the florigen gene RFT1 are the main cause of late flowering in an indica cultivar, Nona Bokra. Mapping and complementation studies revealed that sequence polymorphisms in the RFT1 regulatory and coding regions are likely to cause late flowering under long-day conditions. We detected polymorphisms in the promoter region that lead to reduced expression levels of RFT1. We also identified an amino acid substitution (E105K that leads to a functional defect in Nona Bokra RFT1. Sequencing of the RFT1 region in rice accessions from a global collection showed that the E105K mutation is found only in indica, and indicated a strong association between the RFT1 haplotype and extremely late flowering in a functional Hd1 background. Furthermore, SNPs in the regulatory region of RFT1 and the E105K substitution in 1,397 accessions show strong linkage disequilibrium with a flowering time-associated SNP. Although the defective E105K allele of RFT1 (but not of another florigen gene, Hd3a is found in many cultivars, relative rate tests revealed no evidence for differential rate of evolution of these genes. The ratios of nonsynonymous to synonymous substitutions suggest that the E105K mutation resulting in the defect in RFT1 occurred relatively recently. These findings indicate that natural mutations in RFT1 provide flowering time divergence under long-day conditions.

Rift propagation at craton margin.: Distribution of faulting and volcanism in the North Tanzanian Divergence (East Africa) during Neogene times

Science.gov (United States)

Le Gall, B.; Nonnotte, P.; Rolet, J.; Benoit, M.; Guillou, H.; Mousseau-Nonnotte, M.; Albaric, J.; Deverchère, J.

2008-02-01

A revised kinematic model is proposed for the Neogene tectono-magmatic development of the North Tanzanian Divergence where the axial valley in S Kenya splits southwards into a wide diverging pattern of block faulting in association with the disappearance of volcanism. Propagation of rifting along the S Kenya proto-rift during the last 8 Ma is first assumed to have operated by linkage of discrete magmatic cells as far S as the Ngorongoro-Kilimanjaro transverse volcanic belt that follows the margin of cratonic blocks in N Tanzania. Strain is believed to have nucleated throughout the thermally-weakened lithosphere in the transverse volcanic belt that might have later linked the S Kenya and N Tanzania rift segments with marked structural changes along-strike. The North Tanzanian Divergence is now regarded as a two-armed rift pattern involving: (1) a wide domain of tilted fault blocks to the W (Mbulu) that encompasses the Eyasi and Manyara fault systems, in direct continuation with the Natron northern trough. The reactivation of basement fabrics in the cold and intact Precambrian lithosphere in the Mbulu domain resulted in an oblique rift pattern that contrasts with the orthogonal extension that prevailed in the Magadi-Natron trough above a more attenuated lithosphere. (2) To the E, the Pangani horst-like range is thought to be a younger (< 1 Ma) structure that formed in response to the relocation of extension S of the Kilimanjaro magmatic center. A significant contrast in the mechanical behaviour of the stretched lithosphere in the North Tanzanian diverging rift is assumed to have occurred on both sides of the Masai cratonic block with a mid-crustal decoupling level to the W where asymmetrical fault-basin patterns are dominant (Magadi-Natron and Mbulu), whereas a component of dynamical uplift is suspected to have caused the topographic elevation of the Pangani range in relation with possible far-travelled mantle melts produced at depth further N.

Computational results for the control of a divergent N-echelon inventory system

NARCIS (Netherlands)

Diks, E.B.; Kok, de A.G.

1996-01-01

Consider a divergent multi-echelon inventory system, e.g., a distribution system or a production system. At every facility in the system orders are placed (or production is initiated) periodically. The order arrives after a fixed lead time. At the end of each period linear costs are incurred at each

Isolation with asymmetric gene flow during the nonsynchronous divergence of dry forest birds.

Science.gov (United States)

Oswald, Jessica A; Overcast, Isaac; Mauck, William M; Andersen, Michael J; Smith, Brian Tilston

2017-03-01

Dry forest bird communities in South America are often fragmented by intervening mountains and rainforests, generating high local endemism. The historical assembly of dry forest communities likely results from dynamic processes linked to numerous population histories among codistributed species. Nevertheless, species may diversify in the same way through time if landscape and environmental features, or species ecologies, similarly structure populations. Here we tested whether six co-distributed taxon pairs that occur in the dry forests of the Tumbes and Marañón Valley of northwestern South America show concordant patterns and modes of diversification. We employed a genome reduction technique, double-digest restriction site-associated DNA sequencing, and obtained 4407-7186 genomewide SNPs. We estimated demographic history in each taxon pair and inferred that all pairs had the same best-fit demographic model: isolation with asymmetric gene flow from the Tumbes into the Marañón Valley, suggesting a common diversification mode. Overall, we also observed congruence in effective population size (N e ) patterns where ancestral N e were 2.9-11.0× larger than present-day Marañón Valley populations and 0.3-2.0× larger than Tumbesian populations. Present-day Marañón Valley N e was smaller than Tumbes. In contrast, we found simultaneous population isolation due to a single event to be unlikely as taxon pairs diverged over an extended period of time (0.1-2.9 Ma) with multiple nonoverlapping divergence periods. Our results show that even when populations of codistributed species asynchronously diverge, the mode of their differentiation can remain conserved over millions of years. Divergence by allopatric isolation due to barrier formation does not explain the mode of differentiation between these two bird assemblages; rather, migration of individuals occurred before and after geographic isolation. © 2017 John Wiley & Sons Ltd.

Divergence in male cricket song and female preference functions in three allopatric sister species.

Science.gov (United States)

Hennig, Ralf Matthias; Blankers, Thomas; Gray, David A

2016-05-01

Multivariate female preference functions for male sexual signals have rarely been investigated, especially in a comparative context among sister species. Here we examined male signal and female preference co-variation in three closely related, but allopatric species of Gryllus crickets and quantified male song traits as well as female preferences. We show that males differ conspicuously in either one of two relatively static song traits, carrier frequency or pulse rate; female preference functions for these traits also differed, and would in combination enhance species discrimination. In contrast, the relatively dynamic song traits, chirp rate and chirp duty cycle, show minimal divergence among species and relatively greater conservation of female preference functions. Notably, among species we demonstrate similar mechanistic rules for the integration of pulse and chirp time scales, despite divergence in pulse rate preferences. As these are allopatric taxa, selection for species recognition per se is unlikely. More likely sexual selection combined with conserved properties of preference filters enabled divergent coevolution of male song and female preferences.

Genome-nutrition divergence: evolving understanding of the malnutrition spectrum.

Science.gov (United States)

Eaton, Jacob C; Iannotti, Lora L

2017-11-01

Humans adapted over a period of 2.3 million years to a diet high in quality and diversity. Genome-nutrition divergence describes the misalignment between modern global diets and the genome formed through evolution. A survey of hominin diets over time shows that humans have thrived on a broad range of foods. Earlier diets were highly diverse and nutrient dense, in contrast to modern food systems in which monotonous diets of staple cereals and ultraprocessed foods play a more prominent role. Applying the lens of genome-nutrition divergence to malnutrition reveals shared risk factors for undernutrition and overnutrition at nutrient, food, and environmental levels. Mechanisms for food system shifts, such as crop-neutral agricultural policy, agroecology, and social policy, are explored as a means to realign modern diets with the nutritional patterns to which humans may be better adapted to thrive. © The Author(s) 2017. Published by Oxford University Press on behalf of the International Life Sciences Institute. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Dimensional regularization and infrared divergences in quantum electrodynamics

International Nuclear Information System (INIS)

Marculescu, S.

1979-01-01

Dimensional continuation was devised as a powerful regularization method for ultraviolet divergences in quantum field theories. Recently it was clear, at least for quantum electrodynamics, that such a method could be employed for factorizing out infrared divergences from the on-shell S-matrix elements. This provides a renormalization scheme on the electron mass-shell without using a gauge violating ''photon mass''. (author)

Divergent Perturbation Series

International Nuclear Information System (INIS)

Suslov, I.M.

2005-01-01

Various perturbation series are factorially divergent. The behavior of their high-order terms can be determined by Lipatov's method, which involves the use of instanton configurations of appropriate functional integrals. When the Lipatov asymptotic form is known and several lowest order terms of the perturbation series are found by direct calculation of diagrams, one can gain insight into the behavior of the remaining terms of the series, which can be resummed to solve various strong-coupling problems in a certain approximation. This approach is demonstrated by determining the Gell-Mann-Low functions in φ 4 theory, QED, and QCD with arbitrary coupling constants. An overview of the mathematical theory of divergent series is presented, and interpretation of perturbation series is discussed. Explicit derivations of the Lipatov asymptotic form are presented for some basic problems in theoretical physics. A solution is proposed to the problem of renormalon contributions, which hampered progress in this field in the late 1970s. Practical perturbation-series summation schemes are described both for a coupling constant of order unity and in the strong-coupling limit. An interpretation of the Borel integral is given for 'non-Borel-summable' series. Higher order corrections to the Lipatov asymptotic form are discussed

Demography and genome divergence of lake and stream populations of an East African cichlid fish.

Science.gov (United States)

Egger, Bernd; Roesti, Marius; Böhne, Astrid; Roth, Olivia; Salzburger, Walter

2017-10-01

Disentangling the processes and mechanisms underlying adaptive diversification is facilitated by the comparative study of replicate population pairs that have diverged along a similar environmental gradient. Such a setting is realized in a cichlid fish from southern Lake Tanganyika, Astatotilapia burtoni, which occurs within the lake proper as well as in various affluent rivers. Previously, we demonstrated that independent lake and stream populations show similar adaptations to the two habitat regimes. However, little is known about the evolutionary and demographic history of the A. burtoni populations in question and the patterns of genome divergence among them. Here, we apply restriction site-associated DNA sequencing (RADseq) to examine the evolutionary history, the population structure and genomic differentiation of lake and stream populations in A. burtoni. A phylogenetic reconstruction based on genome-wide molecular data largely resolved the evolutionary relationships among populations, allowing us to re-evaluate the independence of replicate lake-stream population clusters. Further, we detected a strong pattern of isolation by distance, with baseline genomic divergence increasing with geographic distance and decreasing with the level of gene flow between lake and stream populations. Genome divergence patterns were heterogeneous and inconsistent among lake-stream population clusters, which is explained by differences in divergence times, levels of gene flow and local selection regimes. In line with the latter, we only detected consistent outlier loci when the most divergent lake-stream population pair was excluded. Several of the thus identified candidate genes have inferred functions in immune and neuronal systems and show differences in gene expression between lake and stream populations. © 2017 John Wiley & Sons Ltd.

Divergência genética entre progênies de café robusta Genetic divergence among robusta coffe progenies

Directory of Open Access Journals (Sweden)

Milana Gonçalves Ivoglo

2008-12-01

Full Text Available Estudou-se a divergência genética de 21 progênies de meios-irmãos - 19 do grupo Congolês e duas do grupo Guineano - de introduções do germoplasma de café robusta (Coffea canephora do IAC. O estudo baseou-se em análises multivariadas de 14 características morfo-agronômicas, com o propósito de selecionar as progênies mais divergentes, visando à definição de população-base para posterior seleção e produção de híbridos. Avaliou-se também a importância das características discriminantes para análises de divergência, visando ao descarte das variáveis, segundo suas contribuições relativas. O experimento foi plantado e desenvolvido em campo experimental localizado no Pólo Regional do Nordeste Paulista, Mococa (SP, em blocos casualizados, com 21 tratamentos e 24 repetições. O agrupamento dos genótipos foi realizado com base nos métodos de Tocher e UPGMA. A matriz de dissimilaridade genética foi obtida por meio da distância generalizada de Mahalanobis, que serviu de base para a formação dos grupos. Os métodos empregados foram eficientes em detectar ampla variabilidade genética entre as progênies avaliadas. Vários grupos dissimilares foram identificados. As progênies IAC 2262, IAC 2290, IAC 2286, IAC 2292 e IAC 2291 são indicadas para compor programas de intercruzamentos, por terem sido consideradas as mais promissoras na obtenção de populações segregantes ou híbridos heteróticos. As características que menos contribuíram para a divergência genética foram, hierarquicamente: diâmetro da copa antes da poda, altura da planta antes da poda e área foliar.It was studied genetic divergence of 21 half-sib progenies, being 19 of the Congolês group and two of the Guineano group, introductions of germoplasma robust (Coffea canephora, based in 14 morpho-agronomic traits and multivariate procedures. It's aims to select the lineages most divergent for definition of population-base for posterior reciprocal

Micropolar Fluids Using B-spline Divergence Conforming Spaces

KAUST Repository

Sarmiento, Adel

2014-06-06

We discretized the two-dimensional linear momentum, microrotation, energy and mass conservation equations from micropolar fluids theory, with the finite element method, creating divergence conforming spaces based on B-spline basis functions to obtain pointwise divergence free solutions [8]. Weak boundary conditions were imposed using Nitsche\\'s method for tangential conditions, while normal conditions were imposed strongly. Once the exact mass conservation was provided by the divergence free formulation, we focused on evaluating the differences between micropolar fluids and conventional fluids, to show the advantages of using the micropolar fluid model to capture the features of complex fluids. A square and an arc heat driven cavities were solved as test cases. A variation of the parameters of the model, along with the variation of Rayleigh number were performed for a better understanding of the system. The divergence free formulation was used to guarantee an accurate solution of the flow. This formulation was implemented using the framework PetIGA as a basis, using its parallel stuctures to achieve high scalability. The results of the square heat driven cavity test case are in good agreement with those reported earlier.

On the Lamb vector divergence as a momentum field diagnostic employed in turbulent channel flow

Science.gov (United States)

Hamman, Curtis W.; Kirby, Robert M.; Klewicki, Joseph C.

2006-11-01

Vorticity, enstrophy, helicity, and other derived field variables provide invaluable information about the kinematics and dynamics of fluids. However, whether or not derived field variables exist that intrinsically identify spatially localized motions having a distinct capacity to affect a time rate of change of linear momentum is seldom addressed in the literature. The purpose of the present study is to illustrate the unique attributes of the divergence of the Lamb vector in order to qualify its potential for characterizing such spatially localized motions. Toward this aim, we describe the mathematical properties, near-wall behavior, and scaling characteristics of the divergence of the Lamb vector for turbulent channel flow. When scaled by inner variables, the mean divergence of the Lamb vector merges to a single curve in the inner layer, and the fluctuating quantities exhibit a strong correlation with the Bernoulli function throughout much of the inner layer.

Role of mantle flow in Nubia-Somalia plate divergence

Science.gov (United States)

Stamps, D. S.; Iaffaldano, G.; Calais, E.

2015-01-01

Present-day continental extension along the East African Rift System (EARS) has often been attributed to diverging sublithospheric mantle flow associated with the African Superplume. This implies a degree of viscous coupling between mantle and lithosphere that remains poorly constrained. Recent advances in estimating present-day opening rates along the EARS from geodesy offer an opportunity to address this issue with geodynamic modeling of the mantle-lithosphere system. Here we use numerical models of the global mantle-plates coupled system to test the role of present-day mantle flow in Nubia-Somalia plate divergence across the EARS. The scenario yielding the best fit to geodetic observations is one where torques associated with gradients of gravitational potential energy stored in the African highlands are resisted by weak continental faults and mantle basal drag. These results suggest that shear tractions from diverging mantle flow play a minor role in present-day Nubia-Somalia divergence.

Training in the adolescent brain : An fMRI training study on divergent thinking

NARCIS (Netherlands)

Kleibeuker, S.W.; Stevenson, C.E.; van der Aar, L.; Overgaauw, S.; van Duijvenvoorde, Anna C.; Crone, E.A.

Prior research suggests that adolescence is a time of enhanced sensitivity for practice and learning. In this study we tested the neural correlates of divergent thinking training in 15-to 16-year-old adolescents relative to an age-matched active control group. All participants performed an

Rotational and divergent kinetic energy in the mesoscale model ALADIN

Directory of Open Access Journals (Sweden)

V. Blažica

2013-03-01

Full Text Available Kinetic energy spectra from the mesoscale numerical weather prediction (NWP model ALADIN with horizontal resolution 4.4 km are split into divergent and rotational components which are then compared at horizontal scales below 300 km and various vertical levels. It is shown that about 50% of kinetic energy in the free troposphere in ALADIN is divergent energy. The percentage increases towards 70% near the surface and in the upper troposphere towards 100 hPa. The maximal percentage of divergent energy is found at stratospheric levels around 100 hPa and at scales below 100 km which are not represented by the global models. At all levels, the divergent energy spectra are characterised by shallower slopes than the rotational energy spectra, and the difference increases as horizontal scales become larger. A very similar vertical distribution of divergent energy is obtained by using the standard ALADIN approach for the computation of spectra based on the extension zone and by applying detrending approach commonly used in mesoscale NWP community.

Symbolic interactionism and critical perspective: divergent or synergistic?

Science.gov (United States)

Burbank, Patricia M; Martins, Diane C

2010-01-01

Throughout their history, symbolic interactionism and critical perspective have been viewed as divergent theoretical perspectives with different philosophical underpinnings. A review of their historical and philosophical origins reveals both points of divergence and areas of convergence. Their underlying philosophies of science and views of human freedom are different as is their level of focus with symbolic interactionism having a micro perspective and critical perspective using a macro perspective. This micro/macro difference is reflected in the divergence of their major concepts, goals and basic tenets. While their underlying philosophies are different, however, they are not necessarily contradictory and areas of convergence may include the concepts of reference groups and looking glass self within symbolic interactionism and ideological hegemony within critical perspective. By using a pragmatic approach and combining symbolic interactionism and critical perspectives, both micro and macro levels come into focus and strategies for change across individual and societal levels can be developed and applied. Application of both symbolic interactionism and critical perspective to nursing research and scholarship offers exciting new opportunities for theory development and research methodologies. In nursing education, these two perspectives can give students added insight into patients' and families' problems at the micro level while, at the same time, giving them a lens to see and tools to apply to problems at the macro level in health care. In nursing practice, a combined symbolic interactionism/critical perspective approach assists nurses to give high-quality care at the individual level while also working at the macro level to address the manufacturers of illness. New research questions emerge from this combination of perspectives with new possibilities for theory development, a transformation in nursing education, and the potential for new practice strategies that

Boiling flow through diverging microchannel

Indian Academy of Sciences (India)

such systems, for small pressure drop penalty and with good flow stability. .... ied the effect of divergence angle on mean and transient pressure/temperature distribution and .... supplying a fixed voltage and current using a power source meter.

Deformed statistics Kullback–Leibler divergence minimization within a scaled Bregman framework

International Nuclear Information System (INIS)

Venkatesan, R.C.; Plastino, A.

2011-01-01

The generalized Kullback–Leibler divergence (K–Ld) in Tsallis statistics [constrained by the additive duality of generalized statistics (dual generalized K–Ld)] is here reconciled with the theory of Bregman divergences for expectations defined by normal averages, within a measure-theoretic framework. Specifically, it is demonstrated that the dual generalized K–Ld is a scaled Bregman divergence. The Pythagorean theorem is derived from the minimum discrimination information principle using the dual generalized K–Ld as the measure of uncertainty, with constraints defined by normal averages. The minimization of the dual generalized K–Ld, with normal averages constraints, is shown to exhibit distinctly unique features. -- Highlights: ► Dual generalized Kullback–Leibler divergence (K–Ld) proven to be scaled Bregman divergence in continuous measure-theoretic framework. ► Minimum dual generalized K–Ld condition established with normal averages constraints. ► Pythagorean theorem derived.

O Cabimento dos Embargos de Divergência

OpenAIRE

LOURENCO, S. R.

2012-01-01

A presente pesquisa objetiva demonstrar os embargos de divergência com enfoque nos elementos processuais do cabimento de tal modalidade recursal em nosso ordenamento jurídico. Para tanto, investigaremos os aspectos gerais dos embargos de divergência, a partir da análise dos elementos históricos enquanto a criação do instituto, como também sua finalidade e classificação no ordenamento jurídico brasileiro. Após, analisaremos o requisito de admissibilidade do cabimento dos embargo...

Riverscape genetics identifies replicated ecological divergence across an Amazonian ecotone.

Science.gov (United States)

Cooke, Georgina M; Landguth, Erin L; Beheregaray, Luciano B

2014-07-01

Ecological speciation involves the evolution of reproductive isolation and niche divergence in the absence of a physical barrier to gene flow. The process is one of the most controversial topics of the speciation debate, particularly in tropical regions. Here, we investigate ecologically based divergence across an Amazonian ecotone in the electric fish, Steatogenys elegans. We combine phylogenetics, genome scans, and population genetics with a recently developed individual-based evolutionary landscape genetics approach that incorporates selection. This framework is used to assess the relative contributions of geography and divergent natural selection between environments as biodiversity drivers. We report on two closely related and sympatric lineages that exemplify how divergent selection across a major Amazonian aquatic ecotone (i.e., between rivers with markedly different hydrochemical properties) may result in replicated ecologically mediated speciation. The results link selection across an ecological gradient with reproductive isolation and we propose that assortative mating based on water color may be driving the divergence. Divergence resulting from ecologically driven selection highlights the importance of considering environmental heterogeneity in studies of speciation in tropical regions. Furthermore, we show that framing ecological speciation in a spatially explicit evolutionary landscape genetics framework provides an important first step in exploring a wide range of the potential effects of spatial dependence in natural selection. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

High mutation rates explain low population genetic divergence at copy-number-variable loci in Homo sapiens.

Science.gov (United States)

Hu, Xin-Sheng; Yeh, Francis C; Hu, Yang; Deng, Li-Ting; Ennos, Richard A; Chen, Xiaoyang

2017-02-22

Copy-number-variable (CNV) loci differ from single nucleotide polymorphic (SNP) sites in size, mutation rate, and mechanisms of maintenance in natural populations. It is therefore hypothesized that population genetic divergence at CNV loci will differ from that found at SNP sites. Here, we test this hypothesis by analysing 856 CNV loci from the genomes of 1184 healthy individuals from 11 HapMap populations with a wide range of ancestry. The results show that population genetic divergence at the CNV loci is generally more than three times lower than at genome-wide SNP sites. Populations generally exhibit very small genetic divergence (G st  = 0.05 ± 0.049). The smallest divergence is among African populations (G st  = 0.0081 ± 0.0025), with increased divergence among non-African populations (G st  = 0.0217 ± 0.0109) and then among African and non-African populations (G st  = 0.0324 ± 0.0064). Genetic diversity is high in African populations (~0.13), low in Asian populations (~0.11), and intermediate in the remaining 11 populations. Few significant linkage disequilibria (LDs) occur between the genome-wide CNV loci. Patterns of gametic and zygotic LDs indicate the absence of epistasis among CNV loci. Mutation rate is about twice as large as the migration rate in the non-African populations, suggesting that the high mutation rates play dominant roles in producing the low population genetic divergence at CNV loci.

Converging or Diverging Lens?

Science.gov (United States)

Branca, Mario

2013-01-01

Why does a lens magnify? Why does it shrink objects? Why does this happen? The activities that we propose here are useful in helping us to understand how lenses work, and they show that the same lens can have different magnification capabilities. A converging lens can also act as a diverging lens. (Contains 4 figures.)

Training in the Adolescent Brain: An FMRI Training Study on Divergent Thinking

Science.gov (United States)

Kleibeuker, Sietske W.; Stevenson, Claire E.; van der Aar, Laura; Overgaauw, Sandy; van Duijvenvoorde, Anna C.; Crone, Eveline A.

2017-01-01

Prior research suggests that adolescence is a time of enhanced sensitivity for practice and learning. In this study we tested the neural correlates of divergent thinking training in 15- to 16-year-old adolescents relative to an age-matched active control group. All participants performed an alternative uses task, a valid measure to test divergent…

Whole genome investigation of a divergent clade of the pathogen Streptococcus suis

Directory of Open Access Journals (Sweden)

Abiyad eBaig

2015-11-01

Full Text Available Streptococcus suis is a major porcine and zoonotic pathogen responsible for significant economic losses in the pig industry and an increasing number of human cases. Multiple isolates of S. suis show marked genomic diversity. Here we report the analysis of whole genome sequences of nine pig isolates that caused disease typical of S. suis and had phenotypic characteristics of S. suis, but their genomes were divergent from those of many other S. suis isolates. Comparison of protein sequences predicted from divergent genomes with those from normal S. suis reduced the size of core genome from 793 to only 397 genes. Divergence was clear if phylogenetic analysis was performed on reduced core genes and MLST alleles. Phylogenies based on certain other genes (16S rRNA, sodA, recN and cpn60 did not show divergence for all isolates, suggesting recombination between some divergent isolates with normal S. suis for these genes. Indeed, there is evidence of recent recombination between the divergent and normal S. suis genomes for 249 of 397 core genes. In addition, phylogenetic analysis based on the 16S rRNA gene and 132 genes that were conserved between the divergent isolates and representatives of the broader Streptococcus genus showed that divergent isolates were more closely related to S. suis. Six out of nine divergent isolates possessed a S. suis-like capsule region with variation in capsular gene sequences but the remaining three did not have a discrete capsule locus. The majority (40/70, of virulence-associated genes in normal S. suis were present in the divergent genomes. Overall, the divergent isolates extend the current diversity of S. suis species but the phenotypic similarities and the large amount of gene exchange with normal S. suis gives insufficient evidence to assign these isolates to a new species or subspecies. Further sampling and whole genome analysis of more isolates is warranted to understand the diversity of the species.

Determining the Effect of Natural Selection on Linked Neutral Divergence across Species.

Science.gov (United States)

Phung, Tanya N; Huber, Christian D; Lohmueller, Kirk E

2016-08-01

A major goal in evolutionary biology is to understand how natural selection has shaped patterns of genetic variation across genomes. Studies in a variety of species have shown that neutral genetic diversity (intra-species differences) has been reduced at sites linked to those under direct selection. However, the effect of linked selection on neutral sequence divergence (inter-species differences) remains ambiguous. While empirical studies have reported correlations between divergence and recombination, which is interpreted as evidence for natural selection reducing linked neutral divergence, theory argues otherwise, especially for species that have diverged long ago. Here we address these outstanding issues by examining whether natural selection can affect divergence between both closely and distantly related species. We show that neutral divergence between closely related species (e.g. human-primate) is negatively correlated with functional content and positively correlated with human recombination rate. We also find that neutral divergence between distantly related species (e.g. human-rodent) is negatively correlated with functional content and positively correlated with estimates of background selection from primates. These patterns persist after accounting for the confounding factors of hypermutable CpG sites, GC content, and biased gene conversion. Coalescent models indicate that even when the contribution of ancestral polymorphism to divergence is small, background selection in the ancestral population can still explain a large proportion of the variance in divergence across the genome, generating the observed correlations. Our findings reveal that, contrary to previous intuition, natural selection can indirectly affect linked neutral divergence between both closely and distantly related species. Though we cannot formally exclude the possibility that the direct effects of purifying selection drive some of these patterns, such a scenario would be possible only

Behavioural divergence, interfertility and speciation: a review.

Science.gov (United States)

Pillay, Neville; Rymer, Tasmin L

2012-11-01

Behavioural compatibility between mates is fundamental for maintaining species boundaries and is achieved through appropriate communication between males and females. A breakdown in communication will lead to behavioural divergence and reduced interfertility. In this review, we summarise the current knowledge on male signals and female perception of these signals, integrating the literature from several taxa. We advocate that signaller-perceiver coevolution, which is usually under strong stabilising selection to enable mating, forms the basis of species-specific mate recognition systems. The mechanisms (phylogeny, geography, ecology, biology) shaping signaller-perceiver systems are briefly discussed to demonstrate the factors underpinning the evolution of signaller-perceiver couplings. Since divergence and diversification of communication systems is driven by changes in the mechanical properties of sensory pathways and morphology of sensory organs, we highlight signal modalities (auditory, olfactory, visual, tactile) and their importance in communication, particularly in mate selection. Next, using available examples and generating a stylised model, we suggest how disruption (biological, ecological, stochastic) of signaller-perceiver systems drives behavioural divergence and consequently results in reduced interfertility and speciation. Future studies should adopt an integrative approach, combining multiple parameters (phylogeny, adaptive utility of communication systems, genetics and biomechanical/biochemical properties of signals and perception) to explore how disruption of signaller-perceiver systems results in behavioural divergence and reduced interfertility. Finally, we question the impact that rapid environmental change will have on disruption of communication systems, potentially interfering with signaller-perceiver couplings. Copyright © 2012 Elsevier B.V. All rights reserved.

14-19 Education across Great Britain--Convergence or Divergence?

Science.gov (United States)

Gunning, Dennis; Raffe, David

2011-01-01

This article reviews recent policies for 14-19 learning in Wales and Scotland, and discusses the extent to which these policies have diverged from England following parliamentary devolution in 1999. It distinguishes different types of divergence and suggests that many policy differences have not been about major issues of educational philosophy or…

Single nucleotide polymorphisms unravel hierarchical divergence and signatures of selection among Alaskan sockeye salmon (Oncorhynchus nerka populations

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Habicht Christopher

2011-02-01

Full Text Available Abstract Background Disentangling the roles of geography and ecology driving population divergence and distinguishing adaptive from neutral evolution at the molecular level have been common goals among evolutionary and conservation biologists. Using single nucleotide polymorphism (SNP multilocus genotypes for 31 sockeye salmon (Oncorhynchus nerka populations from the Kvichak River, Alaska, we assessed the relative roles of geography (discrete boundaries or continuous distance and ecology (spawning habitat and timing driving genetic divergence in this species at varying spatial scales within the drainage. We also evaluated two outlier detection methods to characterize candidate SNPs responding to environmental selection, emphasizing which mechanism(s may maintain the genetic variation of outlier loci. Results For the entire drainage, Mantel tests suggested a greater role of geographic distance on population divergence than differences in spawn timing when each variable was correlated with pairwise genetic distances. Clustering and hierarchical analyses of molecular variance indicated that the largest genetic differentiation occurred between populations from distinct lakes or subdrainages. Within one population-rich lake, however, Mantel tests suggested a greater role of spawn timing than geographic distance on population divergence when each variable was correlated with pairwise genetic distances. Variable spawn timing among populations was linked to specific spawning habitats as revealed by principal coordinate analyses. We additionally identified two outlier SNPs located in the major histocompatibility complex (MHC class II that appeared robust to violations of demographic assumptions from an initial pool of eight candidates for selection. Conclusions First, our results suggest that geography and ecology have influenced genetic divergence between Alaskan sockeye salmon populations in a hierarchical manner depending on the spatial scale. Second

Navier–Stokes flow in converging–diverging distensible tubes

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Taha Sochi

2015-09-01

Full Text Available We use a method based on the lubrication approximation in conjunction with a residual-based mass-continuity iterative solution scheme to compute the flow rate and pressure field in distensible converging–diverging tubes for Navier–Stokes fluids. We employ an analytical formula derived from a one-dimensional version of the Navier–Stokes equations to describe the underlying flow model that provides the residual function. This formula correlates the flow rate to the boundary pressures in straight cylindrical elastic tubes with constant-radius. We validate our findings by the convergence toward a final solution with fine discretization as well as by comparison to the Poiseuille-type flow in its convergence toward analytic solutions found earlier in rigid converging–diverging tubes. We also tested the method on limiting special cases of cylindrical elastic tubes with constant-radius where the numerical solutions converged to the expected analytical solutions. The distensible model has also been endorsed by its convergence toward the rigid Poiseuille-type model with increasing the tube wall stiffness. Lubrication-based one-dimensional finite element method was also used for verification. In this investigation five converging–diverging geometries are used for demonstration, validation and as prototypes for modeling converging–diverging geometries in general.

Camouflage target detection via hyperspectral imaging plus information divergence measurement

Science.gov (United States)

Chen, Yuheng; Chen, Xinhua; Zhou, Jiankang; Ji, Yiqun; Shen, Weimin

2016-01-01

Target detection is one of most important applications in remote sensing. Nowadays accurate camouflage target distinction is often resorted to spectral imaging technique due to its high-resolution spectral/spatial information acquisition ability as well as plenty of data processing methods. In this paper, hyper-spectral imaging technique together with spectral information divergence measure method is used to solve camouflage target detection problem. A self-developed visual-band hyper-spectral imaging device is adopted to collect data cubes of certain experimental scene before spectral information divergences are worked out so as to discriminate target camouflage and anomaly. Full-band information divergences are measured to evaluate target detection effect visually and quantitatively. Information divergence measurement is proved to be a low-cost and effective tool for target detection task and can be further developed to other target detection applications beyond spectral imaging technique.

Evolutionary divergence in the fungal response to fluconazole revealed by soft clustering

KAUST Repository

Kuo, Dwight

2010-07-23

Background: Fungal infections are an emerging health risk, especially those involving yeast that are resistant to antifungal agents. To understand the range of mechanisms by which yeasts can respond to anti-fungals, we compared gene expression patterns across three evolutionarily distant species - Saccharomyces cerevisiae, Candida glabrata and Kluyveromyces lactis - over time following fluconazole exposure. Results: Conserved and diverged expression patterns were identified using a novel soft clustering algorithm that concurrently clusters data from all species while incorporating sequence orthology. The analysis suggests complementary strategies for coping with ergosterol depletion by azoles - Saccharomyces imports exogenous ergosterol, Candida exports fluconazole, while Kluyveromyces does neither, leading to extreme sensitivity. In support of this hypothesis we find that only Saccharomyces becomes more azole resistant in ergosterol-supplemented media; that this depends on sterol importers Aus1 and Pdr11; and that transgenic expression of sterol importers in Kluyveromyces alleviates its drug sensitivity. Conclusions: We have compared the dynamic transcriptional responses of three diverse yeast species to fluconazole treatment using a novel clustering algorithm. This approach revealed significant divergence among regulatory programs associated with fluconazole sensitivity. In future, such approaches might be used to survey a wider range of species, drug concentrations and stimuli to reveal conserved and divergent molecular response pathways.

Evolutionary divergence in the fungal response to fluconazole revealed by soft clustering

KAUST Repository

Kuo, Dwight; Tan, Kai; Zinman, Guy; Ravasi, Timothy; Bar-Joseph, Ziv; Ideker, Trey

2010-01-01

Background: Fungal infections are an emerging health risk, especially those involving yeast that are resistant to antifungal agents. To understand the range of mechanisms by which yeasts can respond to anti-fungals, we compared gene expression patterns across three evolutionarily distant species - Saccharomyces cerevisiae, Candida glabrata and Kluyveromyces lactis - over time following fluconazole exposure. Results: Conserved and diverged expression patterns were identified using a novel soft clustering algorithm that concurrently clusters data from all species while incorporating sequence orthology. The analysis suggests complementary strategies for coping with ergosterol depletion by azoles - Saccharomyces imports exogenous ergosterol, Candida exports fluconazole, while Kluyveromyces does neither, leading to extreme sensitivity. In support of this hypothesis we find that only Saccharomyces becomes more azole resistant in ergosterol-supplemented media; that this depends on sterol importers Aus1 and Pdr11; and that transgenic expression of sterol importers in Kluyveromyces alleviates its drug sensitivity. Conclusions: We have compared the dynamic transcriptional responses of three diverse yeast species to fluconazole treatment using a novel clustering algorithm. This approach revealed significant divergence among regulatory programs associated with fluconazole sensitivity. In future, such approaches might be used to survey a wider range of species, drug concentrations and stimuli to reveal conserved and divergent molecular response pathways.

Design and testing of low-divergence elliptical-jet nozzles

Energy Technology Data Exchange (ETDEWEB)

Rouly, Etienne; Warkentin, Andrew; Bauer, Robert [Dalhousie University, Halifax (China)

2015-05-15

A novel approach was developed to design and fabricate nozzles to produce high-pressure low-divergence fluid jets. Rapid-prototype fabrication allowed for myriad experiments investigating effects of different geometric characteristics of nozzle internal geometry on jet divergence angle and fluid distribution. Nozzle apertures were elliptical in shape with aspect ratios between 1.00 and 2.45. The resulting nozzle designs were tested and the lowest elliptical jet divergence angle was 0.4 degrees. Nozzle pressures and flowrates ranged from 0.32 to 4.45 MPa and 13.6 to 37.9 LPM, respectively. CimCool CimTech 310 machining fluid was used in all experiments at a Brix concentration of 6.6 percent.

Electroluminescence and electrical degradation of insulating polymers at electrode interfaces under divergent fields

Science.gov (United States)

Zhang, Shuai; Li, Qi; Hu, Jun; Zhang, Bo; He, Jinliang

2018-04-01

Electrical degradation of insulating polymers at electrode interfaces is an essential factor in determining long-term reliability. A critical challenge is that the exact mechanism of degradation is not fully understood, either experimentally or theoretically, due to the inherent complex processes. Consequently, in this study, we investigate electroluminescence (EL) at the interface of an electrode and insulator, and determine the relationship between EL and electrical degradation. Using a tip-plate electrode structure, the unique features of EL under a highly divergent field are investigated. The voltage type (alternating or direct current), the polymer matrix, and the time of pressing are also investigated separately. A study of EL from insulators under a divergent field is provided, and the relationship between EL spectra and degradation is discussed. It is shown that EL spectra under a divergent field have unique characteristics compared with EL spectra from polymer films under a uniform field and the most obvious one is the UV emission. The results obtained in the current investigation bring us a step closer to understanding the process of electrical degradation and provide a potential way to diagnose insulator defects.

Chloroplast DNA Structural Variation, Phylogeny, and Age of Divergence among Diploid Cotton Species

Science.gov (United States)

Li, Pengbo; Liu, Fang; Wang, Yumei; Xu, Qin; Shang, Mingzhao; Zhou, Zhongli; Cai, Xiaoyan; Wang, Xingxing; Wendel, Jonathan F.; Wang, Kunbo

2016-01-01

The cotton genus (Gossypium spp.) contains 8 monophyletic diploid genome groups (A, B, C, D, E, F, G, K) and a single allotetraploid clade (AD). To gain insight into the phylogeny of Gossypium and molecular evolution of the chloroplast genome in this group, we performed a comparative analysis of 19 Gossypium chloroplast genomes, six reported here for the first time. Nucleotide distance in non-coding regions was about three times that of coding regions. As expected, distances were smaller within than among genome groups. Phylogenetic topologies based on nucleotide and indel data support for the resolution of the 8 genome groups into 6 clades. Phylogenetic analysis of indel distribution among the 19 genomes demonstrates contrasting evolutionary dynamics in different clades, with a parallel genome downsizing in two genome groups and a biased accumulation of insertions in the clade containing the cultivated cottons leading to large (for Gossypium) chloroplast genomes. Divergence time estimates derived from the cpDNA sequence suggest that the major diploid clades had diverged approximately 10 to 11 million years ago. The complete nucleotide sequences of 6 cpDNA genomes are provided, offering a resource for cytonuclear studies in Gossypium. PMID:27309527

Divergence in function and expression of the NOD26-like intrinsic proteins in plants

Directory of Open Access Journals (Sweden)

Feng Ying

2009-07-01

Full Text Available Abstract Background NOD26-like intrinsic proteins (NIPs that belong to the aquaporin superfamily are plant-specific and exhibit a similar three-dimensional structure. Experimental evidences however revealed that functional divergence should have extensively occurred among NIP genes. It is therefore intriguing to further investigate the evolutionary mechanisms being responsible for the functional diversification of the NIP genes. To better understand this process, a comprehensive analysis including the phylogenetic, positive selection, functional divergence, and transcriptional analysis was carried out. Results The origination of NIPs could be dated back to the primitive land plants, and their diversification would be no younger than the emergence time of the moss P. patens. The rapid proliferation of NIPs in plants may be primarily attributed to the segmental chromosome duplication produced by polyploidy and tandem duplications. The maximum likelihood analysis revealed that NIPs should have experienced strong selective pressure for adaptive evolution after gene duplication and/or speciation, prompting the formation of distinct NIP groups. Functional divergence analysis at the amino acid level has provided strong statistical evidence for shifted evolutionary rate and/or radical change of the physiochemical properties of amino acids after gene duplication, and DIVERGE2 has identified the critical amino acid sites that are thought to be responsible for the divergence for further investigation. The expression of plant NIPs displays a distinct tissue-, cell-type-, and developmental specific pattern, and their responses to various stress treatments are quite different also. The differences in organization of cis-acting regulatory elements in the promoter regions may partially explain their distinction in expression. Conclusion A number of analyses both at the DNA and amino acid sequence levels have provided strong evidences that plant NIPs have

On the Borel summability of divergent solutions of the heat equation

OpenAIRE

Lutz, D. A.; Miyake, M.; Schäfke, R.

1999-01-01

In recent years, the theory of Borel summability or multisummability of divergent power series of one variable has been established and it has been proved that every formal solution of an ordinary differential equation with irregular singular point is multisummable. For partial differential equations the summability problem for divergent solutions has not been studied so well, and in this paper we shall try to develop the Borel summability of divergent solutions of the Cauch...

Universal portfolios generated by the Bregman divergence

Science.gov (United States)

Tan, Choon Peng; Kuang, Kee Seng

2017-04-01

The Bregman divergence of two probability vectors is a stronger form of the f-divergence introduced by Csiszar. Two versions of the Bregman universal portfolio are presented by exploiting the mean-value theorem. The explicit form of the Bregman universal portfolio generated by a function of a convex polynomial is derived and studied empirically. This portfolio can be regarded as another generalized of the well-known Helmbold portfolio. By running the portfolios on selected stock-price data sets from the local stock exchange, it is shown that it is possible to increase the wealth of the investor by using the portfolios in investment.

Divergent plate motion drives rapid exhumation of (ultra)high pressure rocks

Science.gov (United States)

Liao, Jie; Malusà, Marco G.; Zhao, Liang; Baldwin, Suzanne L.; Fitzgerald, Paul G.; Gerya, Taras

2018-06-01

Exhumation of (ultra)high pressure [(U)HP] rocks by upper-plate divergent motion above an unbroken slab, first proposed in the Western Alps, has never been tested by numerical methods. We present 2D thermo-mechanical models incorporating subduction of a thinned continental margin beneath either a continental or oceanic upper plate, followed by upper-plate divergent motion away from the lower plate. Results demonstrate how divergent plate motion may trigger rapid exhumation of large volumes of (U)HP rocks directly to the Earth's surface, without the need for significant overburden removal by erosion. Model exhumation paths are fully consistent with natural examples for a wide range of upper-plate divergence rates. Exhumation rates are systematically higher than the divergent rate imposed to the upper plate, and the modeled size of exhumed (U)HP domes is invariant for different rates of upper-plate divergence. Major variations are instead predicted at depth for differing model scenarios, as larger amounts of divergent motion may allow mantle-wedge exhumation to shallow depth under the exhuming domes. The transient temperature increase, due to ascent of mantle-wedge material in the subduction channel, has a limited effect on exhumed continental (U)HP rocks already at the surface. We test two examples, the Cenozoic (U)HP terranes of the Western Alps (continental upper plate) and eastern Papua New Guinea (oceanic upper plate). The good fit between model predictions and the geologic record in these terranes encourages the application of these models globally to pre-Cenozoic (U)HP terranes where the geologic record of exhumation is only partly preserved.

Potencial de melhoramento e divergência genética de cultivares de milho-pipoca Potential to breeding and genetic divergence in popcorn cultivars

Directory of Open Access Journals (Sweden)

Glauco Vieira Miranda

2003-06-01

Full Text Available O objetivo deste trabalho foi avaliar o potencial de melhoramento e a divergência genética de nove cultivares tropicais de milho-pipoca. A divergência genética foi estimada por meio da técnica de análise multivariada e as cultivares foram agrupadas com base na distância generalizada de Mahalanobis (DGM, utilizando o método de otimização de Tocher e a dispersão gráfica. Com produtividade de grãos acima de 3 t/ha, destacaram-se as cultivares CMS 43, IAC 112, Viçosa, CMS 42 e Branco, e com índices de capacidade de expansão acima de 24 (v/v, as cultivares IAC 112, RS 20 e Zélia. As estimativas da DGM indicaram (RS 20 e Beija-flor e (Rosa-claro e RS 20 os pares de cultivares mais distantes geneticamente, e (IAC 112 e Viçosa e (Branco e CMS 42, os pares mais similares. Foram identificados três ou quatro grupos divergentes dependendo do método de agrupamento. Para o melhoramento de milho-pipoca, as cultivares com maiores potenciais são RS 20, Zélia, IAC 112 e Beija-flor. As cultivares apresentam divergência genética.The objective of this paper was to evaluate the potential of breeding and genetic divergence in nine tropical popcorn cultivars. The genetic divergence was estimated using multivariate analysis techniques and the cultivars were grouped based in Mahalanobis' generalized distance (MGD, using Tocher's optimization and graphic dispersion. The best cultivars concerning the yield grain above 3 ton/ha were CMS 43, IAC 112, Viçosa, CMS 42 and Branco, and to popping expansion above 24 (v/v were IAC 112, RS 20 and Zélia. The estimates of MGD indicated the pairs genetically more distant (RS 20, Beija-flor and (Rosa-claro, RS 20 as well as pairs genetically more similar (IAC 112, Viçosa and (Branco, CMS 42. Tree or four genetic divergences groups were formed depending on the method. To popcorn breeding, cultivars with best potential are RS 20, Zélia, IAC 112, and Beija-flor. The cultivars show genetic divergence.

Multigene analyses resolve early diverging lineages in the Rhodymeniophycidae (Florideophyceae, Rhodophyta).

Science.gov (United States)

Saunders, Gary W; Filloramo, Gina; Dixon, Kyatt; Le Gall, Line; Maggs, Christine A; Kraft, Gerald T

2016-08-01

Multigene phylogenetic analyses were directed at resolving the earliest divergences in the red algal subclass Rhodymeniophycidae. The inclusion of key taxa (new to science and/or previously lacking molecular data), additional sequence data (SSU, LSU, EF2, rbcL, COI-5P), and phylogenetic analyses removing the most variable sites (site stripping) have provided resolution for the first time at these deep nodes. The earliest diverging lineage within the subclass was the enigmatic Catenellopsis oligarthra from New Zealand (Catenellopsidaceae), which is here placed in the Catenellopsidales ord. nov. In our analyses, Atractophora hypnoides was not allied with the other included Bonnemaisoniales, but resolved as sister to the Peyssonneliales, and is here assigned to Atractophoraceae fam. nov. in the Atractophorales ord. nov. Inclusion of Acrothesaurum gemellifilum gen. et sp. nov. from Tasmania has greatly improved our understanding of the Acrosymphytales, to which we assign three families, the Acrosymphytaceae, Acrothesauraceae fam. nov. and Schimmelmanniaceae fam. nov. © 2016 Phycological Society of America.

Converging Wages, Diverging GRP: Directed Technical Change and Endogenous Growth. Empirical Analysis of Growth Patterns across Kazakh regions

OpenAIRE

Alisher Aldashev

2011-01-01

The paper analyzes unequal regional development in Kazakhstan. Applying the nonlinear least squares method in presence of spatial correlation we estimate the convergence rate of wages across Kazakh regions for the period 2003-2009. The estimated convergence rate is about 3% which is somewhat higher than estimates obtained for the USA and Europe. At the same time there is slight divergence in the GRP per capita. It is argued that convergence in wages which coincides with divergence in the per ...

Regulatory divergence of X-linked genes and hybrid male sterility in mice.

Science.gov (United States)

Oka, Ayako; Shiroishi, Toshihiko

2014-01-01

Postzygotic reproductive isolation is the reduction of fertility or viability in hybrids between genetically diverged populations. One example of reproductive isolation, hybrid male sterility, may be caused by genetic incompatibility between diverged genetic factors in two distinct populations. Genetic factors involved in hybrid male sterility are disproportionately located on the X chromosome. Recent studies showing the evolutionary divergence in gene regulatory networks or epigenetic effects suggest that the genetic incompatibilities occur at much broader levels than had previously been thought (e.g., incompatibility of protein-protein interactions). The latest studies suggest that evolutionary divergence of transcriptional regulation causes genetic incompatibilities in hybrid animals, and that such incompatibilities preferentially involve X-linked genes. In this review, we focus on recent progress in understanding hybrid sterility in mice, including our studies, and we discuss the evolutionary significance of regulatory divergence for speciation.

An Exponential Regulator for Rapidity Divergences

Energy Technology Data Exchange (ETDEWEB)

Li, Ye [Fermilab; Neill, Duff [MIT, Cambridge, CTP; Zhu, Hua Xing [MIT, Cambridge, CTP

2016-04-01

Finding an efficient and compelling regularization of soft and collinear degrees of freedom at the same invariant mass scale, but separated in rapidity is a persistent problem in high-energy factorization. In the course of a calculation, one encounters divergences unregulated by dimensional regularization, often called rapidity divergences. Once regulated, a general framework exists for their renormalization, the rapidity renormalization group (RRG), leading to fully resummed calculations of transverse momentum (to the jet axis) sensitive quantities. We examine how this regularization can be implemented via a multi-differential factorization of the soft-collinear phase-space, leading to an (in principle) alternative non-perturbative regularization of rapidity divergences. As an example, we examine the fully-differential factorization of a color singlet's momentum spectrum in a hadron-hadron collision at threshold. We show how this factorization acts as a mother theory to both traditional threshold and transverse momentum resummation, recovering the classical results for both resummations. Examining the refactorization of the transverse momentum beam functions in the threshold region, we show that one can directly calculate the rapidity renormalized function, while shedding light on the structure of joint resummation. Finally, we show how using modern bootstrap techniques, the transverse momentum spectrum is determined by an expansion about the threshold factorization, leading to a viable higher loop scheme for calculating the relevant anomalous dimensions for the transverse momentum spectrum.

Differentiation of retarded integrals and the divergence theorem for retarded functions with discontinuities

International Nuclear Information System (INIS)

Cooperstock, F.I.; Lim, P.H.

1986-01-01

Theorems expressing the time derivatives of retarded volume and surface integrals are presented as well as the Gauss divergence theorem for retarded functions with discontinuities. These theorems greatly facilitate the analysis of gravitational radiation from the motion of disjoint matter distributions in general relativity and could find useful application in other branches of physics

Prevalence of anopheline species and their Plasmodium infection status in epidemic-prone border areas of Bangladesh

Directory of Open Access Journals (Sweden)

Nazib Forida

2010-01-01

Full Text Available Abstract Background Information related to malaria vectors is very limited in Bangladesh. In the changing environment and various Anopheles species may be incriminated and play role in the transmission cycle. This study was designed with an intention to identify anopheline species and possible malaria vectors in the border belt areas, where the malaria is endemic in Bangladesh. Methods Anopheles mosquitoes were collected from three border belt areas (Lengura, Deorgachh and Matiranga during the peak malaria transmission season (May to August. Three different methods were used: human landing catches, resting collecting by mouth aspirator and CDC light traps. Enzyme-linked immunosorbent assay (ELISA was done to detect Plasmodium falciparum, Plasmodium vivax-210 and Plasmodium vivax-247 circumsporozoite proteins (CSP from the collected female species. Results A total of 634 female Anopheles mosquitoes belonging to 17 species were collected. Anopheles vagus (was the dominant species (18.6% followed by Anopheles nigerrimus (14.5% and Anopheles philippinensis (11.0%. Infection rate was found 2.6% within 622 mosquitoes tested with CSP-ELISA. Eight (1.3% mosquitoes belonging to five species were positive for P. falciparum, seven (1.1% mosquitoes belonging to five species were positive for P. vivax -210 and a single mosquito (0.2% identified as Anopheles maculatus was positive for P. vivax-247. No mixed infection was found. Highest infection rate was found in Anopheles karwari (22.2% followed by An. maculatus (14.3% and Anopheles barbirostris (9.5%. Other positive species were An. nigerrimus (4.4%, An. vagus (4.3%, Anopheles subpictus (1.5% and An. philippinensis (1.4%. Anopheles vagus and An. philippinensis were previously incriminated as malaria vector in Bangladesh. In contrast, An. karwari, An. maculatus, An. barbirostris, An. nigerrimus and An. subpictus had never previously been incriminated in Bangladesh. Conclusion Findings of this study suggested

Summation of all-loop UV divergences in maximally supersymmetric gauge theories

International Nuclear Information System (INIS)

Borlakov, A.T.; Kazakov, D.I.; Tolkachev, D.M.; Vlasenko, D.E.

2016-01-01

We consider the leading and subleading UV divergences for the four-point on-shell scattering amplitudes in D=6,8,10 supersymmetric Yang-Mills theories in the planar limit. These theories belong to the class of maximally supersymmetric gauge theories and presumably possess distinguished properties beyond perturbation theory. In the previous works, we obtained the recursive relations that allow one to get the leading and subleading divergences in all loops in a pure algebraic way. The all loop summation of the leading divergences is performed with the help of the differential equations which are the generalization of the RG equations for non-renormalizable theories. Here we mainly focus on solving and analyzing these equations. We discuss the properties of the obtained solutions and interpretation of the results. The key issue is that the summation of infinite series for the leading and the subleading divergences does improve the situation and does not allow one to remove the regularization and obtain the finite answer. This means that despite numerous cancellations of divergent diagrams these theories remain non-renormalizable.

Summation of all-loop UV divergences in maximally supersymmetric gauge theories

Energy Technology Data Exchange (ETDEWEB)

Borlakov, A.T. [Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research,Dubna (Russian Federation); Moscow Institute of Physics and Technology,Dolgoprudny (Russian Federation); Kazakov, D.I. [Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research,Dubna (Russian Federation); Alikhanov Institute for Theoretical and Experimental Physics,Moscow (Russian Federation); Moscow Institute of Physics and Technology,Dolgoprudny (Russian Federation); Tolkachev, D.M. [Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research,Dubna (Russian Federation); Stepanov Institute of Physics,Minsk (Belarus); Vlasenko, D.E. [Department of Physics, South Federal State University,Rostov-Don (Russian Federation)

2016-12-29

We consider the leading and subleading UV divergences for the four-point on-shell scattering amplitudes in D=6,8,10 supersymmetric Yang-Mills theories in the planar limit. These theories belong to the class of maximally supersymmetric gauge theories and presumably possess distinguished properties beyond perturbation theory. In the previous works, we obtained the recursive relations that allow one to get the leading and subleading divergences in all loops in a pure algebraic way. The all loop summation of the leading divergences is performed with the help of the differential equations which are the generalization of the RG equations for non-renormalizable theories. Here we mainly focus on solving and analyzing these equations. We discuss the properties of the obtained solutions and interpretation of the results. The key issue is that the summation of infinite series for the leading and the subleading divergences does improve the situation and does not allow one to remove the regularization and obtain the finite answer. This means that despite numerous cancellations of divergent diagrams these theories remain non-renormalizable.

Principal Curves for Statistical Divergences and an Application to Finance

Directory of Open Access Journals (Sweden)

Ana Flávia P. Rodrigues

2018-05-01

Full Text Available This paper proposes a method for the beta pricing model under the consideration of non-Gaussian returns by means of a generalization of the mean-variance model and the use of principal curves to define a divergence model for the optimization of the pricing model. We rely on the q-exponential model so consider the properties of the divergences which are used to describe the statistical model and fully characterize the behavior of the assets. We derive the minimum divergence portfolio, which generalizes the Markowitz’s (mean-divergence approach and relying on the information geometrical aspects of the distributions the Capital Asset Pricing Model (CAPM is then derived under the geometrical characterization of the distributions which model the data, all by the consideration of principal curves approach. We discuss the possibility of integration of our model into an adaptive procedure that can be used for the search of optimum points on finance applications.

Speciation in rapidly diverging systems: lessons from Lake Malawi.

Science.gov (United States)

Danley, P D; Kocher, T D

2001-05-01

Rapid evolutionary radiations provide insight into the fundamental processes involved in species formation. Here we examine the diversification of one such group, the cichlid fishes of Lake Malawi, which have radiated from a single ancestor into more than 400 species over the past 700 000 years. The phylogenetic history of this group suggests: (i) that their divergence has proceeded in three major bursts of cladogenesis; and (ii) that different selective forces have dominated each cladogenic event. The first episode resulted in the divergence of two major lineages, the sand- and rock-dwellers, each adapted to a major benthic macrohabitat. Among the rock-dwellers, competition for trophic resources then drove a second burst of cladogenesis, which resulted in the differentiation of trophic morphology. The third episode of cladogenesis is associated with differentiation of male nuptial colouration, most likely in response to divergent sexual selection. We discuss models of speciation in relation to this observed pattern. We advocate a model, divergence with gene flow, which reconciles the disparate selective forces responsible for the diversification of this group and suggest that the nonadaptive nature of the tertiary episode has significantly contributed to the extraordinary species richness of this group.

Divergence and adaptive evolution of the gibberellin oxidase genes in plants.

Science.gov (United States)

Huang, Yuan; Wang, Xi; Ge, Song; Rao, Guang-Yuan

2015-09-29

The important phytohormone gibberellins (GAs) play key roles in various developmental processes. GA oxidases (GAoxs) are critical enzymes in GA synthesis pathway, but their classification, evolutionary history and the forces driving the evolution of plant GAox genes remain poorly understood. This study provides the first large-scale evolutionary analysis of GAox genes in plants by using an extensive whole-genome dataset of 41 species, representing green algae, bryophytes, pteridophyte, and seed plants. We defined eight subfamilies under the GAox family, namely C19-GA2ox, C20-GA2ox, GA20ox,GA3ox, GAox-A, GAox-B, GAox-C and GAox-D. Of these, subfamilies GAox-A, GAox-B, GAox-C and GAox-D are described for the first time. On the basis of phylogenetic analyses and characteristic motifs of GAox genes, we demonstrated a rapid expansion and functional divergence of the GAox genes during the diversification of land plants. We also detected the subfamily-specific motifs and potential sites of some GAox genes, which might have evolved under positive selection. GAox genes originated very early-before the divergence of bryophytes and the vascular plants and the diversification of GAox genes is associated with the functional divergence and could be driven by positive selection. Our study not only provides information on the classification of GAox genes, but also facilitates the further functional characterization and analysis of GA oxidases.

Divergent trophic levels in two cryptic sibling bat species.

Science.gov (United States)

Siemers, Björn M; Greif, Stefan; Borissov, Ivailo; Voigt-Heucke, Silke L; Voigt, Christian C

2011-05-01

Changes in dietary preferences in animal species play a pivotal role in niche specialization. Here, we investigate how divergence of foraging behaviour affects the trophic position of animals and thereby their role for ecosystem processes. As a model, we used two closely related bat species, Myotis myotis and M. blythii oxygnathus, that are morphologically very similar and share the same roosts, but show clear behavioural divergence in habitat selection and foraging. Based on previous dietary studies on synanthropic populations in Central Europe, we hypothesised that M. myotis would mainly prey on predatory arthropods (i.e., secondary consumers) while M. blythii oxygnathus would eat herbivorous insects (i.e., primary consumers). We thus expected that the sibling bats would be at different trophic levels. We first conducted a validation experiment with captive bats in the laboratory and measured isotopic discrimination, i.e., the stepwise enrichment of heavy in relation to light isotopes between consumer and diet, in insectivorous bats for the first time. We then tested our trophic level hypothesis in the field at an ancient site of natural coexistence for the two species (Bulgaria, south-eastern Europe) using stable isotope analyses. As predicted, secondary consumer arthropods (carabid beetles; Coleoptera) were more enriched in (15)N than primary consumer arthropods (tettigoniids; Orthoptera), and accordingly wing tissue of M. myotis was more enriched in (15)N than tissue of M. blythii oxygnathus. According to a Bayesian mixing model, M. blythii oxygnathus indeed fed almost exclusively on primary consumers (98%), while M. myotis ate a mix of secondary (50%), but also, and to a considerable extent, primary consumers (50%). Our study highlights that morphologically almost identical, sympatric sibling species may forage at divergent trophic levels, and, thus may have different effects on ecosystem processes.

Genomic islands of divergence are not affected by geography of speciation in sunflowers.

Science.gov (United States)

Renaut, S; Grassa, C J; Yeaman, S; Moyers, B T; Lai, Z; Kane, N C; Bowers, J E; Burke, J M; Rieseberg, L H

2013-01-01

Genomic studies of speciation often report the presence of highly differentiated genomic regions interspersed within a milieu of weakly diverged loci. The formation of these speciation islands is generally attributed to reduced inter-population gene flow near loci under divergent selection, but few studies have critically evaluated this hypothesis. Here, we report on transcriptome scans among four recently diverged pairs of sunflower (Helianthus) species that vary in the geographical context of speciation. We find that genetic divergence is lower in sympatric and parapatric comparisons, consistent with a role for gene flow in eroding neutral differences. However, genomic islands of divergence are numerous and small in all comparisons, and contrary to expectations, island number and size are not significantly affected by levels of interspecific gene flow. Rather, island formation is strongly associated with reduced recombination rates. Overall, our results indicate that the functional architecture of genomes plays a larger role in shaping genomic divergence than does the geography of speciation.

Ancient geographical barriers drive differentiation among Sonneratia caseolaris populations and recent divergence from S. lanceolata

Directory of Open Access Journals (Sweden)

Yuchen Yang

2016-10-01

Full Text Available Glacial vicariance is thought to influence population dynamics and speciation of many marine organisms. Mangroves, a plant group inhabiting intertidal zones, were also profoundly influenced by Pleistocene glaciations. In this study, we investigated phylogeographic patterns of a widespread mangrove species Sonneratia caseolaris and a narrowly distributed, closely related species S. lanceolata to infer their divergence histories and related it to historical geological events. We sequenced two chloroplast fragments and five nuclear genes for one population of S. lanceolata and 12 populations of S. caseolaris across the Indo-West Pacific (IWP region to evaluate genetic differentiation and divergence time among them. Phylogenetic analysis based on sequences of nuclear ribosomal internal transcribed spacer (nrITS and a nuclear gene rpl9 for all Sonneratia species indicate that S. lanceolata individuals are nested within S. caseolaris. We found strong genetic structure among geographic regions (South China Sea, the Indian Ocean and eastern Australia inhabited by S. caseolaris. We estimated that divergence between the Indo-Malesia and Australasia populations occurred 4.035 million years ago (MYA, prior to the onset of Pleistocene. BARRIERS analysis suggested that complex geographic features in the IWP region had largely shaped the phylogeographic patterns of S. caseolaris. Furthermore, haplotype analyses provided convincing evidence for secondary contact of the South China Sea (SCS and the Indian Ocean lineages at the Indo-Pacific boundary. Demographic history inference under isolation and migration (IM model detected substantial gene flow from the Sri Lanka populations to the populations in the Java Island. Moreover, multi-locus sequence analysis indicated that S. lanceolata was most closely related to the Indian Ocean populations of S. caseolaris and the divergence time between them was 2.057 MYA, coinciding with the onset of the Pleistocene

Ecological divergence in the yellow-bellied kingsnake (Lampropeltis calligaster) at two North American biodiversity hotspots.

Science.gov (United States)

McKelvy, A D; Burbrink, F T

2017-01-01

Several biogeographic barriers in the Eastern Nearctic appear to reduce gene flow among populations of many species in predictable ways, however these patterns used to infer process of divergence may be deceiving if alternative modes of diversification are not considered. By using a multilocus statistical phylogeographic approach to examine diversity within a North American snake, Lampropeltis calligaster, we find that mode and timing of speciation near the Mississippi River embayment and peninsular Florida, two main biodiversity hotspots in eastern North America, challenge previously held notions of strict vicariance as the causal factor behind patterns of divergence seen among taxa at these locations. We found three species inhabiting distinct ecological niches with divergences dating to the mid- and early-Pleistocene with subsequently stable or increasing effective population sizes, further supporting the idea that the Pleistocene was an important driver of diversification in North America. Our results lead to a revised hypothesis that ecological divergence has occurred in this group across environments associated with the Mississippi River and at the Florida peninsula. Importantly, in their western distributions, we show that species divergence is associated with the ecological transition from distinct forested habitats to grasslands, rather than the nearby Mississippi River, a barrier often implicated for many other organisms. Additionally, we stress the importance of examining each delimited lineage with respect to conservation, since ecological niche models suggest that by the end of the century changes in climate may negatively alter habitat suitability and, barring adaptation, substantially reduce the suitable range of two of the three species we identified. Copyright © 2016 Elsevier Inc. All rights reserved.

Creative Cognition in Secondary Science: An Exploration of Divergent Thinking in Science among Adolescents

Science.gov (United States)

Antink-Meyer, Allison; Lederman, Norman G.

2015-01-01

The divergent thinking skills in science of 282 US high school students were investigated across 16 weeks of instruction in order to determine whether typical academic time periods can significantly influence changes in thinking skills. Students' from 6 high school science classrooms completed the Scientific Structures Creativity Measure (SSCM)…

A scalable block-preconditioning strategy for divergence-conforming B-spline discretizations of the Stokes problem

KAUST Repository

Cortes, Adriano Mauricio

2016-10-01

The recently introduced divergence-conforming B-spline discretizations allow the construction of smooth discrete velocity-pressure pairs for viscous incompressible flows that are at the same time inf−supinf−sup stable and pointwise divergence-free. When applied to the discretized Stokes problem, these spaces generate a symmetric and indefinite saddle-point linear system. The iterative method of choice to solve such system is the Generalized Minimum Residual Method. This method lacks robustness, and one remedy is to use preconditioners. For linear systems of saddle-point type, a large family of preconditioners can be obtained by using a block factorization of the system. In this paper, we show how the nesting of “black-box” solvers and preconditioners can be put together in a block triangular strategy to build a scalable block preconditioner for the Stokes system discretized by divergence-conforming B-splines. Besides the known cavity flow problem, we used for benchmark flows defined on complex geometries: an eccentric annulus and hollow torus of an eccentric annular cross-section.

Putting scales into evolutionary time: the divergence of major scale insect lineages (Hemiptera) predates the radiation of modern angiosperm hosts

Science.gov (United States)

Vea, Isabelle M.; Grimaldi, David A.

2016-01-01

The radiation of flowering plants in the mid-Cretaceous transformed landscapes and is widely believed to have fuelled the radiations of major groups of phytophagous insects. An excellent group to test this assertion is the scale insects (Coccomorpha: Hemiptera), with some 8,000 described Recent species and probably the most diverse fossil record of any phytophagous insect group preserved in amber. We used here a total-evidence approach (by tip-dating) employing 174 morphological characters of 73 Recent and 43 fossil taxa (48 families) and DNA sequences of three gene regions, to obtain divergence time estimates and compare the chronology of the most diverse lineage of scale insects, the neococcoid families, with the timing of the main angiosperm radiation. An estimated origin of the Coccomorpha occurred at the beginning of the Triassic, about 245 Ma [228–273], and of the neococcoids 60 million years later [210–165 Ma]. A total-evidence approach allows the integration of extinct scale insects into a phylogenetic framework, resulting in slightly younger median estimates than analyses using Recent taxa, calibrated with fossil ages only. From these estimates, we hypothesise that most major lineages of coccoids shifted from gymnosperms onto angiosperms when the latter became diverse and abundant in the mid- to Late Cretaceous. PMID:27000526

Diverging Trade Strategies in Latin America: An Analytical Framework

OpenAIRE

Aggarwal, Vinod K.; Espach, Ralph H.

2003-01-01

Although there is increasing divergence among the trade policies of various Latin American nations, overall the last twenty years have seen a dramatic shift away from protectionism towards liberalization. Focusing on case studies of four Latin American nations — Brazil, Mexico, Chile and Argentina — the authors use an analytical framework to explain the rationales behind divergent policies. The analytical approach used considers the combination of economic, political and strategic objectives ...

Robust bounds on risk-sensitive functionals via Renyi divergence

OpenAIRE

Atar, Rami; Chowdhary, Kamaljit; Dupuis, Paul

2013-01-01

We extend the duality between exponential integrals and relative entropy to a variational formula for exponential integrals involving the Renyi divergence. This formula characterizes the dependence of risk-sensitive functionals and related quantities determined by tail behavior to perturbations in the underlying distributions, in terms of the Renyi divergence. The characterization gives rise to upper and lower bounds that are meaningful for all values of a large deviation scaling parameter, a...

Convergent and Divergent Thinking in the Context of Narrative Mysteries

Science.gov (United States)

Wenzel, William G.; Gerrig, Richard J.

2015-01-01

This project demonstrates how narrative mysteries provide a context in which readers engage in creative cognition. Drawing on the concepts of convergent and divergent thinking, we wrote stories that had either convergent or divergent outcomes. For example, one story had a character give his girlfriend a ring (a convergent outcome), whereas the…

SU-F-T-504: Non-Divergent Planning Method for Craniospinal Irradiation

Energy Technology Data Exchange (ETDEWEB)

Sperling, N; Bogue, J; Parsai, E [University of Toledo Medical Center, Toledo, OH (United States)

2016-06-15

Purpose: Traditional Craniospinal Irradiation (CSI) planning techniques require careful field placement to allow optimal divergence and field overlap at depth, and measurement of skin gap. The result of this is a necessary field overlap resulting in dose heterogeneity in the spinal canal. A novel, nondivergent field matching method has been developed to allow simple treatment planning and delivery without the need to measure skin gap. Methods: The CSI patient was simulated in the prone, and a plan was developed. Bilateral cranial fields were designed with couch and collimator rotation to eliminate divergence with the upper spine field and minimize anterior divergence into the lenses. Spinal posterior-to-anterior fields were designed with the couch rotated to 90 degrees to allow gantry rotation to eliminate divergence at the match line, and the collimator rotated to 90 degrees to allow appropriate field blocking with the MLCs. A match line for the two spinal fields was placed and the gantry rotated to equal angles in opposite directions about the match line. Jaw positions were then defined to allow 1mm overlap at the match line to avoid cold spots. A traditional CSI plan was generated using diverging spinal fields, and a comparison between the two techniques was generated. Results: The non-divergent treatment plan was able to deliver a highly uniform dose to the spinal cord with a cold spot of only 95% and maximum point dose of 115.8%, as compared to traditional plan cold spots of 87% and hot spots of 132% of the prescription dose. Conclusion: A non-divergent method for planning CSI patients has been developed and clinically implemented. Planning requires some geometric manipulation in order to achieve an adequate dose distribution, however, it can help to manage cold spots and simplify the shifts needed between spinal fields.

SU-F-T-504: Non-Divergent Planning Method for Craniospinal Irradiation

International Nuclear Information System (INIS)

Sperling, N; Bogue, J; Parsai, E

2016-01-01

Purpose: Traditional Craniospinal Irradiation (CSI) planning techniques require careful field placement to allow optimal divergence and field overlap at depth, and measurement of skin gap. The result of this is a necessary field overlap resulting in dose heterogeneity in the spinal canal. A novel, nondivergent field matching method has been developed to allow simple treatment planning and delivery without the need to measure skin gap. Methods: The CSI patient was simulated in the prone, and a plan was developed. Bilateral cranial fields were designed with couch and collimator rotation to eliminate divergence with the upper spine field and minimize anterior divergence into the lenses. Spinal posterior-to-anterior fields were designed with the couch rotated to 90 degrees to allow gantry rotation to eliminate divergence at the match line, and the collimator rotated to 90 degrees to allow appropriate field blocking with the MLCs. A match line for the two spinal fields was placed and the gantry rotated to equal angles in opposite directions about the match line. Jaw positions were then defined to allow 1mm overlap at the match line to avoid cold spots. A traditional CSI plan was generated using diverging spinal fields, and a comparison between the two techniques was generated. Results: The non-divergent treatment plan was able to deliver a highly uniform dose to the spinal cord with a cold spot of only 95% and maximum point dose of 115.8%, as compared to traditional plan cold spots of 87% and hot spots of 132% of the prescription dose. Conclusion: A non-divergent method for planning CSI patients has been developed and clinically implemented. Planning requires some geometric manipulation in order to achieve an adequate dose distribution, however, it can help to manage cold spots and simplify the shifts needed between spinal fields.

Neogene-dominated diversification in neotropical montane lichens: dating divergence events in the lichen-forming fungal genus Oropogon (Parmeliaceae).

Science.gov (United States)

Leavitt, Steven D; Esslinger, Theodore L; Lumbsch, H Thorsten

2012-11-01

Diversification in neotropical regions has been attributed to both Tertiary geological events and Pleistocene climatic fluctuations. However, the timing and processes driving speciation in these regions remain unexplored in many important groups. Here, we address the timing of diversification in the neotropical lichenized fungal genus Oropogon (Ascomycota) and assess traditional species boundaries. We analyzed sequence data from three loci to assess phenotypically circumscribed Oropogon species from the Oaxacan Highlands, Mexico. We provide a comparison of dated divergence estimates between concatenated gene trees and a calibrated multilocus species-tree using substitution rates for two DNA regions. We also compare estimates from a data set excluding ambiguously aligned regions and a data set including the hyper-variable regions in two ribosomal markers. Phylogenetic reconstructions were characterized by well-supported monophyletic clades corresponding to traditionally circumscribed species, with the exception of a single taxon. Divergence estimates indicate that most diversification of the sampled Oropogon species occurred throughout the Oligocene and Miocene, although diversification of a single closely related clade appears to have occurred during the late Pliocene and into the Pleistocene. Divergence estimates calculated from a data set with ambiguously aligned regions removed were much more recent than those from the full data set. Overall, our analyses place the majority of divergence events of Oropogon species from the Oaxacan Highlands within the Neogene and provide strong evidence that climatic changes during the Pleistocene were not a major factor driving speciation in the lichenized genus Oropogon in neotropical highlands.

Hemispheric connectivity and the visual-spatial divergent-thinking component of creativity.

Science.gov (United States)

Moore, Dana W; Bhadelia, Rafeeque A; Billings, Rebecca L; Fulwiler, Carl; Heilman, Kenneth M; Rood, Kenneth M J; Gansler, David A

2009-08-01

Divergent thinking is an important measurable component of creativity. This study tested the postulate that divergent thinking depends on large distributed inter- and intra-hemispheric networks. Although preliminary evidence supports increased brain connectivity during divergent thinking, the neural correlates of this characteristic have not been entirely specified. It was predicted that visuospatial divergent thinking would correlate with right hemisphere white matter volume (WMV) and with the size of the corpus callosum (CC). Volumetric magnetic resonance imaging (MRI) analyses and the Torrance Tests of Creative Thinking (TTCT) were completed among 21 normal right-handed adult males. TTCT scores correlated negatively with the size of the CC and were not correlated with right or, incidentally, left WMV. Although these results were not predicted, perhaps, as suggested by Bogen and Bogen (1988), decreased callosal connectivity enhances hemispheric specialization, which benefits the incubation of ideas that are critical for the divergent-thinking component of creativity, and it is the momentary inhibition of this hemispheric independence that accounts for the illumination that is part of the innovative stage of creativity. Alternatively, decreased CC size may reflect more selective developmental pruning, thereby facilitating efficient functional connectivity.

Wetlands explain most in the genetic divergence pattern of Oncomelania hupensis.

Science.gov (United States)

Liang, Lu; Liu, Yang; Liao, Jishan; Gong, Peng

2014-10-01

Understanding the divergence patterns of hosts could shed lights on the prediction of their parasite transmission. No effort has been devoted to understand the drivers of genetic divergence pattern of Oncomelania hupensis, the only intermediate host of Schistosoma japonicum. Based on a compilation of two O. hupensis gene datasets covering a wide geographic range in China and an array of geographical distance and environmental dissimilarity metrics built from earth observation data and ecological niche modeling, we conducted causal modeling analysis via simple, partial Mantel test and local polynomial fitting to understand the interactions among isolation-by-distance, isolation-by-environment, and genetic divergence. We found that geography contributes more to genetic divergence than environmental isolation, and among all variables involved, wetland showed the strongest correlation with the genetic pairwise distances. These results suggested that in China, O. hupensis dispersal is strongly linked to the distribution of wetlands, and the current divergence pattern of both O. hupensis and schistosomiasis might be altered due to the changed wetland pattern with the accomplishment of the Three Gorges Dam and the South-to-North water transfer project. Copyright © 2014 Elsevier B.V. All rights reserved.

RECONCILIATION OF LANGUAGE VERSIONS WITH DIVERGING MEANINGS IN THE EUROPEAN UNION

Directory of Open Access Journals (Sweden)

Laura-Cristiana SPĂTARU-NEGURĂ

2015-07-01

Full Text Available As emphasized in a study published last year, when multiple legal orders and languages co-exist within a single legal regime, there is potential for divergences between the legal texts. The European Union gives rise to such divergences, having in mind that it integrates 28 Member States and 24 official languages. After discovering how the multilingual and multicultural environment of the European Union affects its legislative and judicial processes and arguing the problem of translation divergences between the authentic texts of the European Union, it is nowadays our concern to analyse the reconciliation of language versions with diverging meanings in the EU legal order. The present study is part of a more complex research on this theme and it is meant to approach certain important points of the master thesis prepared in Switzerland for a LL.M. program.

Divergent phenological response to hydroclimate variability in forested mountain watersheds.

Science.gov (United States)

Hwang, Taehee; Band, Lawrence E; Miniat, Chelcy F; Song, Conghe; Bolstad, Paul V; Vose, James M; Love, Jason P

2014-08-01

Mountain watersheds are primary sources of freshwater, carbon sequestration, and other ecosystem services. There is significant interest in the effects of climate change and variability on these processes over short to long time scales. Much of the impact of hydroclimate variability in forest ecosystems is manifested in vegetation dynamics in space and time. In steep terrain, leaf phenology responds to topoclimate in complex ways, and can produce specific and measurable shifts in landscape forest patterns. The onset of spring is usually delayed at a specific rate with increasing elevation (often called Hopkins' Law; Hopkins, 1918), reflecting the dominant controls of temperature on greenup timing. Contrary with greenup, leaf senescence shows inconsistent trends along elevation gradients. Here, we present mechanisms and an explanation for this variability and its significance for ecosystem patterns and services in response to climate. We use moderate-resolution imaging spectro-radiometer (MODIS) Normalized Difference Vegetation Index (NDVI) data to derive landscape-induced phenological patterns over topoclimate gradients in a humid temperate broadleaf forest in southern Appalachians. These phenological patterns are validated with different sets of field observations. Our data demonstrate that divergent behavior of leaf senescence with elevation is closely related to late growing season hydroclimate variability in temperature and water balance patterns. Specifically, a drier late growing season is associated with earlier leaf senescence at low elevation than at middle elevation. The effect of drought stress on vegetation senescence timing also leads to tighter coupling between growing season length and ecosystem water use estimated from observed precipitation and runoff generation. This study indicates increased late growing season drought may be leading to divergent ecosystem response between high and low elevation forests. Landscape-induced phenological patterns

Divergência genética entre cinco genótipos de melão rendilhado Genetic divergence among five muskmelon cultivars

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Adriana Antonieta do Nascimento Rizzo

2002-06-01

Full Text Available Estimou-se a divergência genética entre cinco genótipos de melão rendilhado (Cucumis melo var. reticulatus Naud. (JAB-20, JAB-21, JAB-22, JAB-23 e 'Bônus nº 2' e determinou-se qual a contribuição relativa das 16 características avaliadas [nº médio de flores masculinas, hermafroditas/planta; produção total de frutos/m², peso médio dos frutos comerciáveis; diâmetro médio transversal e longitudinal do fruto (DMTF e DMLF; diâmetro médio transversal da inserção do pedúculo (DMTP; espessura média do mesocarpo e epicarpo (EMM e EME; diâmetro médio longitudinal e transversal do lóculo (DMTL e DMLL; proporção da cavidade (PC; desprendimento de sementes (DS; teor de sólidos solúveis totais (SST, pH e acidez titulável (AT] na divergência gen��tica. Obtiveram-se dois grupos de similaridade: I- JAB-20, JAB-21 e 'Bônus nº2' e II- JAB-22 e JAB-23. As características DMLF, DMTP, DMLL, DS e SST foram as que mais contribuíram para a divergência genética entre os genótipos.The genetic divergence of five cultivars of muskmelon was estimated (Cucumis melo var. reticulatus Naud (JAB-20, JAB-21, JAB-22, JAB-23 and 'Bônus nº2' and the relative contribution of each 16 characteristics were determined (number of male flowers per plant; total production of fruit, weight of fruits; longitudinal and transversal diameters of fruits; thickness and color of flesh and skin; longitudinal and transversal loculos diameter of fruits; seed loosing; netting thickness; and % total solvers solids, pH and total acidity in genetic divergence. Two groups of similarity were formed between the genitors by the values of D², one of then was constituted of the JAB-20 and JAB-21 and 'Bônus nº 2' genotypes, and another of the JAB-22 and JAB-23. The characteristics of longitudinal loculos diameters, longitudinal diameter of fruits, transversal diameter of peduncle insertion, % total solvers solids and seed loosing contributed to for genetic

Ground state energies from converging and diverging power series expansions

International Nuclear Information System (INIS)

Lisowski, C.; Norris, S.; Pelphrey, R.; Stefanovich, E.; Su, Q.; Grobe, R.

2016-01-01

It is often assumed that bound states of quantum mechanical systems are intrinsically non-perturbative in nature and therefore any power series expansion methods should be inapplicable to predict the energies for attractive potentials. However, if the spatial domain of the Schrödinger Hamiltonian for attractive one-dimensional potentials is confined to a finite length L, the usual Rayleigh–Schrödinger perturbation theory can converge rapidly and is perfectly accurate in the weak-binding region where the ground state’s spatial extension is comparable to L. Once the binding strength is so strong that the ground state’s extension is less than L, the power expansion becomes divergent, consistent with the expectation that bound states are non-perturbative. However, we propose a new truncated Borel-like summation technique that can recover the bound state energy from the diverging sum. We also show that perturbation theory becomes divergent in the vicinity of an avoided-level crossing. Here the same numerical summation technique can be applied to reproduce the energies from the diverging perturbative sums.

Ground state energies from converging and diverging power series expansions

Energy Technology Data Exchange (ETDEWEB)

Lisowski, C.; Norris, S.; Pelphrey, R.; Stefanovich, E., E-mail: eugene-stefanovich@usa.net; Su, Q.; Grobe, R.

2016-10-15

It is often assumed that bound states of quantum mechanical systems are intrinsically non-perturbative in nature and therefore any power series expansion methods should be inapplicable to predict the energies for attractive potentials. However, if the spatial domain of the Schrödinger Hamiltonian for attractive one-dimensional potentials is confined to a finite length L, the usual Rayleigh–Schrödinger perturbation theory can converge rapidly and is perfectly accurate in the weak-binding region where the ground state’s spatial extension is comparable to L. Once the binding strength is so strong that the ground state’s extension is less than L, the power expansion becomes divergent, consistent with the expectation that bound states are non-perturbative. However, we propose a new truncated Borel-like summation technique that can recover the bound state energy from the diverging sum. We also show that perturbation theory becomes divergent in the vicinity of an avoided-level crossing. Here the same numerical summation technique can be applied to reproduce the energies from the diverging perturbative sums.

Divergent Thinking and Hemispheric Dominance for Language Function among Preschool Children.

Science.gov (United States)

Tegano, Deborah Walker; And Others

1983-01-01

An investigation of the relationship of hemispheric dominance (dichotic listening) and divergent thinking (Torrance Tests of Creative Thinking) with 27 preschool children indicates that divergent thinking is associated with right hemispheric dominance in children as young as four years. (Author/PN)

Ecological Divergence and the Origins of Intrinsic Postmating Isolation with Gene Flow

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Aneil F. Agrawal

2011-01-01

Full Text Available The evolution of intrinsic postmating isolation has received much attention, both historically and in recent studies of speciation genes. Intrinsic isolation often stems from between-locus genetic incompatibilities, where alleles that function well within species are incompatible with one another when brought together in the genome of a hybrid. It can be difficult for such incompatibilities to originate when populations diverge with gene flow, because deleterious genotypic combinations will be created and then purged by selection. However, it has been argued that if genes underlying incompatibilities are themselves subject to divergent selection, then they might overcome gene flow to diverge between populations, resulting in the origin of incompatibilities. Nonetheless, there has been little explicit mathematical exploration of such scenarios for the origin of intrinsic incompatibilities during ecological speciation with gene flow. Here we explore theoretical models for the origin of intrinsic isolation where genes subject to divergent natural selection also affect intrinsic isolation, either directly or via linkage disequilibrium with other loci. Such genes indeed overcome gene flow, diverge between populations, and thus result in the evolution of intrinsic isolation. We also examine barriers to neutral gene flow. Surprisingly, we find that intrinsic isolation sometimes weakens this barrier, by impeding differentiation via ecologically based divergent selection.

Computational Investigations in Rectangular Convergent and Divergent Ribbed Channels

Science.gov (United States)

Sivakumar, Karthikeyan; Kulasekharan, N.; Natarajan, E.

2018-05-01

Computational investigations on the rib turbulated flow inside a convergent and divergent rectangular channel with square ribs of different rib heights and different Reynolds numbers (Re=20,000, 40,000 and 60,000). The ribs were arranged in a staggered fashion between the upper and lower surfaces of the test section. Computational investigations are carried out using computational fluid dynamic software ANSYS Fluent 14.0. Suitable solver settings like turbulence models were identified from the literature and the boundary conditions for the simulations on a solution of independent grid. Computations were carried out for both convergent and divergent channels with 0 (smooth duct), 1.5, 3, 6, 9 and 12 mm rib heights, to identify the ribbed channel with optimal performance, assessed using a thermo hydraulic performance parameter. The convergent and divergent rectangular channels show higher Nu values than the standard correlation values.

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

Phylogeography of speciation: allopatric divergence and secondary contact between outcrossing and selfing Clarkia.

Science.gov (United States)

Pettengill, James B; Moeller, David A

2012-09-01

The origins of hybrid zones between parapatric taxa have been of particular interest for understanding the evolution of reproductive isolation and the geographic context of species divergence. One challenge has been to distinguish between allopatric divergence (followed by secondary contact) versus primary intergradation (parapatric speciation) as alternative divergence histories. Here, we use complementary phylogeographic and population genetic analyses to investigate the recent divergence of two subspecies of Clarkia xantiana and the formation of a hybrid zone within the narrow region of sympatry. We tested alternative phylogeographic models of divergence using approximate Bayesian computation (ABC) and found strong support for a secondary contact model and little support for a model allowing for gene flow throughout the divergence process (i.e. primary intergradation). Two independent methods for inferring the ancestral geography of each subspecies, one based on probabilistic character state reconstructions and the other on palaeo-distribution modelling, also support a model of divergence in allopatry and range expansion leading to secondary contact. The membership of individuals to genetic clusters suggests geographic substructure within each taxon where allopatric and sympatric samples are primarily found in separate clusters. We also observed coincidence and concordance of genetic clines across three types of molecular markers, which suggests that there is a strong barrier to gene flow. Taken together, our results provide evidence for allopatric divergence followed by range expansion leading to secondary contact. The location of refugial populations and the directionality of range expansion are consistent with expectations based on climate change since the last glacial maximum. Our approach also illustrates the utility of combining phylogeographic hypothesis testing with species distribution modelling and fine-scale population genetic analyses for inferring

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.)

Ultraviolet divergences in 1/N expansions of quantum field theories

International Nuclear Information System (INIS)

Rim, C.

1984-01-01

For asymptotically free theories, ultraviolet divergencies computed in 1/N expansion with dimensional regularization reduces to simple poles plus powers of Inelement of or finite terms. All divergences are determined by the two loop perturbative renormalization group functions. In an infrared free theory, however, element of = 0 becomes an essential singularity in the 1/N expansion

Combinatorial bounds on the α-divergence of univariate mixture models

KAUST Repository

Nielsen, Frank

2017-06-20

We derive lower- and upper-bounds of α-divergence between univariate mixture models with components in the exponential family. Three pairs of bounds are presented in order with increasing quality and increasing computational cost. They are verified empirically through simulated Gaussian mixture models. The presented methodology generalizes to other divergence families relying on Hellinger-type integrals.

Stora's fine notion of divergent amplitudes

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Joseph C. Várilly

2016-11-01

Full Text Available Stora and coworkers refined the notion of divergent quantum amplitude, somewhat upsetting the standard power-counting recipe. This unexpectedly clears the way to new prototypes for free and interacting field theories of bosons of any mass and spin.

Functional divergence caused by ancient positive selection of a Drosophila hybrid incompatibility locus.

Directory of Open Access Journals (Sweden)

Daniel A Barbash

2004-06-01

Full Text Available Interspecific hybrid lethality and sterility are a consequence of divergent evolution between species and serve to maintain the discrete identities of species. The evolution of hybrid incompatibilities has been described in widely accepted models by Dobzhansky and Muller where lineage-specific functional divergence is the essential characteristic of hybrid incompatibility genes. Experimentally tractable models are required to identify and test candidate hybrid incompatibility genes. Several Drosophila melanogaster genes involved in hybrid incompatibility have been identified but none has yet been shown to have functionally diverged in accordance with the Dobzhansky-Muller model. By introducing transgenic copies of the X-linked Hybrid male rescue (Hmr gene into D. melanogaster from its sibling species D. simulans and D. mauritiana, we demonstrate that Hmr has functionally diverged to cause F1 hybrid incompatibility between these species. Consistent with the Dobzhansky-Muller model, we find that Hmr has diverged extensively in the D. melanogaster lineage, but we also find extensive divergence in the sibling-species lineage. Together, these findings implicate over 13% of the amino acids encoded by Hmr as candidates for causing hybrid incompatibility. The exceptional level of divergence at Hmr cannot be explained by neutral processes because we use phylogenetic methods and population genetic analyses to show that the elevated amino-acid divergence in both lineages is due to positive selection in the distant past-at least one million generations ago. Our findings suggest that multiple substitutions driven by natural selection may be a general phenomenon required to generate hybrid incompatibility alleles.

A limit of the quantum Rényi divergence

International Nuclear Information System (INIS)

Datta, Nilanjana; Leditzky, Felix

2014-01-01

Recently, an interesting quantity called the quantum Rényi divergence (or ‘sandwiched’ Rényi relative entropy) was defined for pairs of positive semi-definite operators ρ and σ. It depends on a parameter α and acts as a parent quantity for other relative entropies which have important operational significance in quantum information theory: the quantum relative entropy and the min- and max-relative entropies. There is, however, another relative entropy, called the 0-relative Rényi entropy, which plays a key role in the analysis of various quantum information-processing tasks in the one-shot setting. We prove that the 0-relative Rényi entropy is obtainable from the quantum Rényi divergence only if ρ and σ have equal supports. This, along with existing results in the literature, suggests that it suffices to consider two essential parent quantities from which operationally relevant entropic quantities can be derived—the quantum Rényi divergence with parameter α ⩾ 1/2, and the α-relative Rényi entropy with α ∈ [0, 1). (paper)

Ayahuasca enhances creative divergent thinking while decreasing conventional convergent thinking.

Science.gov (United States)

Kuypers, K P C; Riba, J; de la Fuente Revenga, M; Barker, S; Theunissen, E L; Ramaekers, J G

2016-09-01

Ayahuasca is a South American psychotropic plant tea traditionally used in Amazonian shamanism. The tea contains the psychedelic 5-HT2A receptor agonist N,N-dimethyltryptamine (DMT), plus β-carboline alkaloids with monoamine oxidase-inhibiting properties. Increasing evidence from anecdotal reports and open-label studies indicates that ayahuasca may have therapeutic effects in treatment of substance use disorders and depression. A recent study on the psychological effects of ayahuasca found that the tea reduces judgmental processing and inner reactivity, classic goals of mindfulness psychotherapy. Another psychological facet that could potentially be targeted by ayahuasca is creative divergent thinking. This mode of thinking can enhance and strengthen psychological flexibility by allowing individuals to generate new and effective cognitive, emotional, and behavioral strategies. The present study aimed to assess the potential effects of ayahuasca on creative thinking. We visited two spiritual ayahuasca workshops and invited participants to conduct creativity tests before and during the acute effects of ayahuasca. In total, 26 participants consented. Creativity tests included the "pattern/line meanings test" (PLMT) and the "picture concept test" (PCT), both assessing divergent thinking and the latter also assessing convergent thinking. While no significant effects were found for the PLMT, ayahuasca intake significantly modified divergent and convergent thinking as measured by the PCT. While convergent thinking decreased after intake, divergent thinking increased. The present data indicate that ayahuasca enhances creative divergent thinking. They suggest that ayahuasca increases psychological flexibility, which may facilitate psychotherapeutic interventions and support clinical trial initiatives.

Divergence time, historical biogeography and evolutionary rate estimation of the order Bangiales (Rhodophyta) inferred from multilocus data

Science.gov (United States)

Xu, Kuipeng; Tang, Xianghai; Wang, Lu; Yu, Xinzi; Sun, Peipei; Mao, Yunxiang

2017-08-01

Bangiales is the only order of the Bangiophyceae and has been suggested to be monophyletic. This order contains approximately 190 species and is distributed worldwide. Previous molecular studies have produced robust phylogenies among the red algae, but the divergence times, historical biogeography and evolutionary rates of Bangiales have rarely been studied. Phylogenetic relationships within the Bangiales were examined using the concatenated gene sets from all available organellar genomes. This analysis has revealed the topology ((( Bangia, Porphyra ) Pyropia ) Wildemania ). Molecular dating indicates that Bangiales diversified approximately 246.40 million years ago (95% highest posterior density (HPD)= 194.78u2013318.24 Ma, posterior probability (PP)=0.99) in the Late Permian and Early Triassic, and that the ancestral species most likely originated from eastern Gondwanaland (currently New Zealand and Australia) and subsequently began to spread and evolve worldwide. Based on pairwise comparisons, we found a slower rate of nucleotide substitutions and lower rates of diversification in Bangiales relative to Florideophyceae. Compared with Viridiplantae (green algae and land plants), the evolutionary rates of Bangiales and other Rhodophyte groups were found to be dramatically faster, by more than 3-fold for plastid genome (ptDNA) and 15-fold for mitochondrial genome (mtDNA). In addition, an average 2.5-fold lower dN/dS was found for the algae than for the land plants, which indicates purifying selection of the algae.

Pollinator Competition as a Driver of Floral Divergence: An Experimental Test.

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Ethan J Temeles

Full Text Available Optimal foraging models of floral divergence predict that competition between two different types of pollinators will result in partitioning, increased assortative mating, and divergence of two floral phenotypes. We tested these predictions in a tropical plant-pollinator system using sexes of purple-throated carib hummingbirds (Anthracothorax jugularis as the pollinators, red and yellow inflorescence morphs of Heliconia caribaea as the plants, and fluorescent dyes as pollen analogs in an enclosed outdoor garden. When foraging alone, males exhibited a significant preference for the yellow morph of H. caribaea, whereas females exhibited no preference. In competition, males maintained their preference for the yellow morph and through aggression caused females to over-visit the red morph, resulting in resource partitioning. Competition significantly increased within-morph dye transfer (assortative mating relative to non-competitive environments. Competition and partitioning of color morphs by sexes of purple-throated caribs also resulted in selection for floral divergence as measured by dye deposition on stigmas. Red and yellow morphs did not differ significantly in dye deposition in the competition trials, but differences in dye deposition and preferences for morphs when sexes of purple-throated caribs foraged alone implied fixation of one or the other color morph in the absence of competition. Competition also resulted in selection for divergence in corolla length, with the red morph experiencing directional selection for longer corollas and the yellow morph experiencing stabilizing selection on corolla length. Our results thus support predictions of foraging models of floral divergence and indicate that pollinator competition is a viable mechanism for divergence in floral traits of plants.

Testing-Based Approach to Determining the Divergence Speed of Slung Loads

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Narayanan Komerath

2018-02-01

Full Text Available When a rotorcraft carries an external slung load, flight speed is often limited by the fear of divergent oscillations, rather than vehicle performance. Since slung objects can be of any shape, incorporating the aerodynamics with sufficient accuracy to predict safe speed has been a problem. The uncertainty forces certifying authorities to set conservative limits on speed to avoid divergence. Obtaining the aerodynamic coefficients of bluff bodies was excessively time-consuming in experiments, and impractical in computations. This review traces the evolution of progress in the area. Prior thinking was to use computations for prediction, with the computational codes validated using a few samples of experiments. This approach has not led to valid general predictions. Data were sparse and a-priori predictions were rarer. A continuous rotation approach has enabled swift measurements of 6-degrees-of-freedom aerodynamic load maps with high resolution about several axes of rotation. The resulting knowledge base in turn permits a swift determination of dynamics up to divergence, with wind tunnel tests where necessary to fill interpolation gaps in the knowledge base. The essence of efficient and swift dynamics simulation with a few well-tested assumptions is described. Under many relevant conditions, the vehicle flight dynamics can be safely decoupled from those of the slung load. While rotor wake swirl causes the payload to rotate at liftoff and landing, this effect can be incorporated into the simulation. Recent success in explaining two well-documented flight test cases provides strong evidence that predictions can be made for most missions swiftly.

ON A PROLONGATION CONSTRUCTION FOR LOCAL NON-DIVERGENT VECTOR FIELDS ON Rn

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A. M. Lukatsky

2015-01-01

Full Text Available The problem of a prolongation of non-divergent vector field, defined in a vicinity of zero in Rn t, to a finite non-divergent vector field on Rn is considered. Explicit formulas for the elements of the simple Lie algebra of non-divergent vector from the well-known Cartan series are obtained. This construction allows to move from the Euler equations for the ideal incompressible fluid to the Euler equations on finite-dimensional Lie groups.

Mitochondrial genome sequences reveal deep divergences among Anopheles punctulatus sibling species in Papua New Guinea

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Logue Kyle

2013-02-01

Full Text Available Abstract Background Members of the Anopheles punctulatus group (AP group are the primary vectors of human malaria in Papua New Guinea. The AP group includes 13 sibling species, most of them morphologically indistinguishable. Understanding why only certain species are able to transmit malaria requires a better comprehension of their evolutionary history. In particular, understanding relationships and divergence times among Anopheles species may enable assessing how malaria-related traits (e.g. blood feeding behaviours, vector competence have evolved. Methods DNA sequences of 14 mitochondrial (mt genomes from five AP sibling species and two species of the Anopheles dirus complex of Southeast Asia were sequenced. DNA sequences from all concatenated protein coding genes (10,770 bp were then analysed using a Bayesian approach to reconstruct phylogenetic relationships and date the divergence of the AP sibling species. Results Phylogenetic reconstruction using the concatenated DNA sequence of all mitochondrial protein coding genes indicates that the ancestors of the AP group arrived in Papua New Guinea 25 to 54 million years ago and rapidly diverged to form the current sibling species. Conclusion Through evaluation of newly described mt genome sequences, this study has revealed a divergence among members of the AP group in Papua New Guinea that would significantly predate the arrival of humans in this region, 50 thousand years ago. The divergence observed among the mtDNA sequences studied here may have resulted from reproductive isolation during historical changes in sea-level through glacial minima and maxima. This leads to a hypothesis that the AP sibling species have evolved independently for potentially thousands of generations. This suggests that the evolution of many phenotypes, such as insecticide resistance will arise independently in each of the AP sibling species studied here.

Enhancing Divergent Search through Extinction Events

DEFF Research Database (Denmark)

Lehman, Joel; Miikkulainen, Risto

2015-01-01

for the capacity to evolve. This hypothesis is tested through experiments in two evolutionary robotics domains. The results show that combining extinction events with divergent search increases evolvability, while combining them with convergent search offers no similar benefit. The conclusion is that extinction...

Regularization of divergent integrals

OpenAIRE

Felder, Giovanni; Kazhdan, David

2016-01-01

We study the Hadamard finite part of divergent integrals of differential forms with singularities on submanifolds. We give formulae for the dependence of the finite part on the choice of regularization and express them in terms of a suitable local residue map. The cases where the submanifold is a complex hypersurface in a complex manifold and where it is a boundary component of a manifold with boundary, arising in string perturbation theory, are treated in more detail.

Gluon mass generation without seagull divergences

International Nuclear Information System (INIS)

Aguilar, Arlene C.; Papavassiliou, Joannis

2010-01-01

Dynamical gluon mass generation has been traditionally plagued with seagull divergences, and all regularization procedures proposed over the years yield finite but scheme-dependent gluon masses. In this work we show how such divergences can be eliminated completely by virtue of a characteristic identity, valid in dimensional regularization. The ability to trigger the aforementioned identity hinges crucially on the particular Ansatz employed for the three-gluon vertex entering into the Schwinger-Dyson equation governing the gluon propagator. The use of the appropriate three-gluon vertex brings about an additional advantage: one obtains two separate (but coupled) integral equations, one for the effective charge and one for the gluon mass. This system of integral equations has a unique solution, which unambiguously determines these two quantities. Most notably, the effective charge freezes in the infrared, and the gluon mass displays power-law running in the ultraviolet, in agreement with earlier considerations.

Conformal anomaly and elimination of infrared divergences in curved spacetime

International Nuclear Information System (INIS)

Grib, A.A.; Nesteruk, A.V.; Pritomanov, S.A.

1984-01-01

The relation between the problem of eliminating the infrared divergences and the conformal anomaly of the regularized energy-momentum tensor is studied in homogeneous isotropic and anisotropic spacetime. It is shown that elimination of the infrared divergence by means of a cutoff or the introduction of a conformally invariant mass of the field leads to the absence of the conformal anomaly

Genetic divergence among Brazilian turmeric germplasm using morpho-agronomical descriptors

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Mário Sérgio Sigrist

2011-01-01

Full Text Available Turmeric (Curcuma longa L. is a vegetatively-propagated crop which is used as a natural dye in the food industryand also presents many biological active compounds. Turmeric conventional breeding is difficult and often limited to germplasmselection. The aim of this study was to evaluate the genetic divergence among turmeric accessions available in Brazil using sevenmorpho-agronomical descriptors. Overall genetic divergence was low, although some divergent genotypes were identified. Fourmain groups of genotypes were identified and could be further used in breeding programs. Canonical variable analysis suggestedthat some descriptors were more important to discriminate accessions and also that one of the descriptors could be discarded. Theresults provided useful insights for better management of the germplasm collection, optimizing conservational and breeding efforts.

Genetic divergence in sesame based on morphological and agronomic traits

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Nair Helena Castro Arriel

2007-01-01

Full Text Available The evaluation of diversity in germplasm collections is important for both plant breeders and germplasmcurators to optimize the use of the variability available. Diversity can be estimated by different genetic markers. The purposeof this study was to estimate the genetic divergence of 30 morphological and agronomic traits in 108 sesame genotypes bymultivariate analysis. The Cole-Rodgers index was used to establish the dissimilarity matrices. The principal componentanalysis identified the traits that contributed most to the divergence and the genotypes were clustered by Tocher’s optimization.Despite the narrow genetic basis, the markers were efficient to characterize the genotypes and identify the most similar groupsor duplicate and divergent genotypes. Greatest variation was found for the traits number of capsules per plant and grain yield.

Divergence-Measure Fields, Sets of Finite Perimeter, and Conservation Laws

Science.gov (United States)

Chen, Gui-Qiang; Torres, Monica

2005-02-01

Divergence-measure fields in L∞ over sets of finite perimeter are analyzed. A notion of normal traces over boundaries of sets of finite perimeter is introduced, and the Gauss-Green formula over sets of finite perimeter is established for divergence-measure fields in L∞. The normal trace introduced here over a class of surfaces of finite perimeter is shown to be the weak-star limit of the normal traces introduced in Chen & Frid [6] over the Lipschitz deformation surfaces, which implies their consistency. As a corollary, an extension theorem of divergence-measure fields in L∞ over sets of finite perimeter is also established. Then we apply the theory to the initial-boundary value problem of nonlinear hyperbolic conservation laws over sets of finite perimeter.

Transcutaneous vagus nerve stimulation (tVNS) enhances divergent thinking.

Science.gov (United States)

Colzato, Lorenza S; Ritter, Simone M; Steenbergen, Laura

2018-03-01

Creativity is one of the most important cognitive skills in our complex and fast-changing world. Previous correlative evidence showed that gamma-aminobutyric acid (GABA) is involved in divergent but not convergent thinking. In the current study, a placebo/sham-controlled, randomized between-group design was used to test a causal relation between vagus nerve and creativity. We employed transcutaneous vagus nerve stimulation (tVNS), a novel non-invasive brain stimulation technique to stimulate afferent fibers of the vagus nerve and speculated to increase GABA levels, in 80 healthy young volunteers. Creative performance was assessed in terms of divergent thinking (Alternate Uses Task) and convergent thinking tasks (Remote Associates Test, Creative Problem Solving Task, Idea Selection Task). Results demonstrate active tVNS, compared to sham stimulation, enhanced divergent thinking. Bayesian analysis reported the data to be inconclusive regarding a possible effect of tVNS on convergent thinking. Therefore, our findings corroborate the idea that the vagus nerve is causally involved in creative performance. Even thought we did not directly measure GABA levels, our results suggest that GABA (likely to be increased in active tVNS condition) supports the ability to select among competing options in high selection demand (divergent thinking) but not in low selection demand (convergent thinking). Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Experimental results on the MOX fuel. Study of the calculus/measures divergences

International Nuclear Information System (INIS)

Martin, S.

1997-01-01

For each nuclear plant unit restart, all safety criterion have to be respected. Various parameters as boron concentration, temperature coefficient, worth or power and activity distributions related to fuel assemblies, have to be calculated. To compute these parameters Framatome uses the neutronic channel Science. Before the validation they are compare to experimental measures. For UO 2 fuel the divergence calculus/measures are correct. But for MOX fuels the divergence worsening. This paper discusses tis divergence and research the origin. (A.L.B.)

Creativity and sensory gating indexed by the P50: selective versus leaky sensory gating in divergent thinkers and creative achievers.

Science.gov (United States)

Zabelina, Darya L; O'Leary, Daniel; Pornpattananangkul, Narun; Nusslock, Robin; Beeman, Mark

2015-03-01

Creativity has previously been linked with atypical attention, but it is not clear what aspects of attention, or what types of creativity are associated. Here we investigated specific neural markers of a very early form of attention, namely sensory gating, indexed by the P50 ERP, and how it relates to two measures of creativity: divergent thinking and real-world creative achievement. Data from 84 participants revealed that divergent thinking (assessed with the Torrance Test of Creative Thinking) was associated with selective sensory gating, whereas real-world creative achievement was associated with "leaky" sensory gating, both in zero-order correlations and when controlling for academic test scores in a regression. Thus both creativity measures related to sensory gating, but in opposite directions. Additionally, divergent thinking and real-world creative achievement did not interact in predicting P50 sensory gating, suggesting that these two creativity measures orthogonally relate to P50 sensory gating. Finally, the ERP effect was specific to the P50 - neither divergent thinking nor creative achievement were related to later components, such as the N100 and P200. Overall results suggest that leaky sensory gating may help people integrate ideas that are outside of focus of attention, leading to creativity in the real world; whereas divergent thinking, measured by divergent thinking tests which emphasize numerous responses within a limited time, may require selective sensory processing more than previously thought. Copyright © 2015 Elsevier Ltd. All rights reserved.

Divergences in maximal supersymmetric Yang-Mills theories in diverse dimensions

International Nuclear Information System (INIS)

Bork, L.V.; Kazakov, D.I.; Kompaniets, M.V.; Tolkachev, D.M.; Vlasenko, D.E.

2015-01-01

The main aim of this paper is to study the scattering amplitudes in gauge field theories with maximal supersymmetry in dimensions D=6,8 and 10. We perform a systematic study of the leading ultraviolet divergences using the spinor helicity and on-shell momentum superspace framework. In D=6 the first divergences start at 3 loops and we calculate them up to 5 loops, in D=8,10 the first divergences start at 1 loop and we calculate them up to 4 loops. The leading divergences in a given order are the polynomials of Mandelstam variables. To be on the safe side, we check our analytical calculations by numerical ones applying the alpha-representation and the dedicated routines. Then we derive an analog of the RG equations for the leading pole that allows us to get the recursive relations and construct the generating procedure to obtain the polynomials at any order of perturbation theory (PT). At last, we make an attempt to sum the PT series and derive the differential equation for the infinite sum. This equation possesses a fixed point which might be stable or unstable depending on the kinematics. Some consequences of these fixed points are discussed.

Ultraviolet divergences in higher dimensional supersymmetric Yang-Mills theories

International Nuclear Information System (INIS)

Howe, P.S.; Stelle, K.S.

1984-01-01

We determine the loop orders for the onset of allowed ultra-violet divergences in higher dimensional supersymmetric Yang-Mills theories. Cancellations are controlled by the non-renormalization theorems for the linearly realizable supersymmetries and by the requirement that counterterms display the full non-linear supersymmetries when the classical equations of motion are imposed. The first allowed divergences in the maximal super Yang-Mills theories occur at four loops in five dimensions, three loops in six dimensions and two loops in seven dimensions. (orig.)

Growth divergence: a challenging opportunity for dendrochronology

Science.gov (United States)

Buras, Allan; Sass-Klaassen, Ute; Wilmking, Martin

2017-04-01

of past climates as well as the response of forest ecosystems to climate change. Buras, A. et al. Tuning the Voices of a Choir: Detecting Ecological Gradients in Time-Series Populations. PLOS ONE 11, e0158346 (2016). Wilmking, M., Juday, G. P., Barber, V. A. & Zald, H. S. J. Recent climate warming forces contrasting growth responses of white spruce at treeline in Alaska through temperature thresholds. Global Change Biology 10, 1724-1736 (2004). D'Arrigo, R., Wilson, R., Liepert, B. & Cherubini, P. On the 'Divergence Problem' in Northern Forests: A review of the tree-ring evidence and possible causes. Global and Planetary Change 60, 289-305 (2008).

Structure of UV divergences in maximally supersymmetric gauge theories

Science.gov (United States)

Kazakov, D. I.; Borlakov, A. T.; Tolkachev, D. M.; Vlasenko, D. E.

2018-06-01

We consider the UV divergences up to sub-subleading order for the four-point on-shell scattering amplitudes in D =8 supersymmetric Yang-Mills theory in the planar limit. We trace how the leading, subleading, etc divergences appear in all orders of perturbation theory. The structure of these divergences is typical for any local quantum field theory independently on renormalizability. We show how the generalized renormalization group equations allow one to evaluate the leading, subleading, etc. contributions in all orders of perturbation theory starting from one-, two-, etc. loop diagrams respectively. We focus then on subtraction scheme dependence of the results and show that in full analogy with renormalizable theories the scheme dependence can be absorbed into the redefinition of the couplings. The only difference is that the role of the couplings play dimensionless combinations like g2s2 or g2t2, where s and t are the Mandelstam variables.

Modified Chapman–Enskog expansion: A new way to treat divergent series

International Nuclear Information System (INIS)

She Zhen-Su

2017-01-01

The resolution by Chen and Sun of divergent Chapman–Enskog expansion problem will not only build a unified foundation for non-equilibrium dynamics modeling at all Mach number and Knudsen number, but also shed light to a large class of difficult theoretical problems involving divergent expansion on strong nonlinearity. (paper)

Multivariate genetic divergence among sugarcane clones by multivariate analysis associated with mixed models

Directory of Open Access Journals (Sweden)

Valéria Rosa Lopes

2014-02-01

Full Text Available This work had the aim to evaluate the genetic divergence in sugarcane clones using the methodology of graphic dispersion by principal components analysis associated to linear mixed models, indentifying the more divergent and productive genotypes with more precision, for a subsequent combination. 138 sugarcane clones of the RB97 series of the Sugarcane Breeding Program of the Universidade Federal do Parana, more two standard cultivars were evaluated in three environments, with two replications. The two first components explained 96% of the total variation, sufficiently for explaining the divergence found. The variable that contributed the most to de divergence was kilogram of brix per plot (BKP followed by brix, mass of 10 stalks and number of stalks per plot. The more divergent sugarcane clones were RB975008, RB975112, RB975019, RB975153 and RB975067 and the more productive clones were RB975269, RB977533, RB975102, RB975317 and RB975038.

Increasing interpersonal trust through divergent thinking

Directory of Open Access Journals (Sweden)

Roberta eSellaro

2014-06-01

Full Text Available Interpersonal trust is an essential ingredient of many social relationships but how stable is it actually, and how is it controlled? There is evidence that the degree of trust into others might be rather volatile and can be affected by manipulations like drawing attention to personal interdependence or independence. Here we investigated whether the degree of interpersonal trust can be biased by inducing either a more integrative or a more cognitive-control mode by means of a creativity task requiring divergent or convergent thinking, respectively. Participants then performed the Trust Game, which provides an index of interpersonal trust by assessing the money units one participant (the trustor transfers to another participant (the trustee. As expected, participants transferred significantly more money to the trustee after engaging in divergent thinking as compared to convergent thinking. This observation provides support for the idea that interpersonal trust is controlled by domain-general (i.e., not socially dedicated cognitive states.

Molecular phylogeny of two unusual brown algae, Phaeostrophion irregulare and Platysiphon glacialis, proposal of the Stschapoviales ord. nov. and Platysiphonaceae fam. nov., and a re-examination of divergence times for brown algal orders.

Science.gov (United States)

Kawai, Hiroshi; Hanyuda, Takeaki; Draisma, Stefano G A; Wilce, Robert T; Andersen, Robert A

2015-10-01

The molecular phylogeny of brown algae was examined using concatenated DNA sequences of seven chloroplast and mitochondrial genes (atpB, psaA, psaB, psbA, psbC, rbcL, and cox1). The study was carried out mostly from unialgal cultures; we included Phaeostrophion irregulare and Platysiphon glacialis because their ordinal taxonomic positions were unclear. Overall, the molecular phylogeny agreed with previously published studies, however, Platysiphon clustered with Halosiphon and Stschapovia and was paraphyletic with the Tilopteridales. Platysiphon resembled Stschapovia in showing remarkable morphological changes between young and mature thalli. Platysiphon, Halosiphon and Stschapovia also shared parenchymatous, terete, erect thalli with assimilatory filaments in whorls or on the distal end. Based on these results, we proposed a new order Stschapoviales and a new family Platysiphonaceae. We proposed to include Phaeostrophion in the Sphacelariales, and we emended the order to include this foliose member. Finally, using basal taxa not included in earlier studies, the origin and divergence times for brown algae were re-investigated. Results showed that the Phaeophyceae branched from Schizocladiophyceae ~260 Ma during the Permian Period. The early diverging brown algae had isomorphic life histories, whereas the derived taxa with heteromorphic life histories evolved 155-110 Ma when they branched from the basal taxa. Based on these results, we propose that the development of heteromorphic life histories and their success in the temperate and cold-water regions was induced by the development of the remarkable seasonality caused by the breakup of Pangaea. Most brown algal orders had diverged by roughly 60 Ma, around the last mass extinction event during the Cretaceous Period, and therefore a drastic climate change might have triggered the divergence of brown algae. © 2015 The Authors. Journal of Phycology published by Wiley Periodicals, Inc. on behalf of Phycological

Molecular Evolution and Expression Divergence of HMT Gene Family in Plants

Directory of Open Access Journals (Sweden)

Man Zhao

2018-04-01

Full Text Available Homocysteine methyltransferase (HMT converts homocysteine to methionine using S-methylmethionine (SMM or S-adenosylmethionine (SAM as methyl donors in organisms, playing an important role in supplying methionine for the growth and the development of plants. To better understand the functions of the HMT genes in plants, we conducted a wide evolution and expression analysis of these genes. Reconstruction of the phylogenetic relationship showed that the HMT gene family was divided into Class 1 and Class 2. In Class 1, HMTs were only found in seed plants, while Class 2 presented in all land plants, which hinted that the HMT genes might have diverged in seed plants. The analysis of gene structures and selection pressures showed that they were relatively conserved during evolution. However, type I functional divergence had been detected in the HMTs. Furthermore, the expression profiles of HMTs showed their distinct expression patterns in different tissues, in which some HMTs were widely expressed in various organs, whereas the others were highly expressed in some specific organs, such as seeds or leaves. Therefore, according to our results in the evolution, functional divergence, and expression, the HMT genes might have diverged during evolution. Further analysis in the expression patterns of AthHMTs with their methyl donors suggested that the diverged HMTs might be related to supply methionine for the development of plant seeds.

Asymptotic states and infrared divergences in gauge theories

International Nuclear Information System (INIS)

Butler, D.R.

1981-01-01

The gauge theories, Gravity and QCD are shown to be infrared finite to a non-trival order by a generalization of the coherent state approach. The asymptotic Hamiltonian operator is used, along with a mathematical theorem by Magnus, to specify a S-operator and to show cancellation of infrared divergences at the amplitude level. This procedure is exemplified in Gravity to third order and applied to QCD for leading order divergences to fifth order in the coupling constant. Dimensional regularization is used to isolate the infrared singularities in QCD. The sections on Gravity include a derivation of the infrared structure of the propagators for a massive particle and the graviton

Bubble Divergences: Sorting out Topology from Cell Structure

Science.gov (United States)

Bonzom, Valentin; Smerlak, Matteo

2012-02-01

We conclude our analysis of bubble divergences in the flat spinfoam model. In [arXiv:1008.1476] we showed that the divergence degree of an arbitrary two-complex Gamma can be evaluated exactly by means of twisted cohomology. Here, we specialize this result to the case where Gamma is the two-skeleton of the cell decomposition of a pseudomanifold, and sharpen it with a careful analysis of the cellular and topological structures involved. Moreover, we explain in detail how this approach reproduces all the previous powercounting results for the Boulatov-Ooguri (colored) tensor models, and sheds light on algebraic-topological aspects of Gurau's 1/N expansion.

An ancient divergence among the bacteria. [methanogenic phylogeny

Science.gov (United States)

Balch, W. E.; Magrum, L. J.; Fox, G. E.; Wolfe, R. S.; Woese, C. R.

1977-01-01

The 16S ribosomal RNZs from two species of met methanogenic bacteria, the mesophile Methanobacterium ruminantium and the thermophile Methanobacterium thermoautotrophicum, have been characterized in terms of the oligonucleotides produced by digestion with T1 ribonuclease. These two organisms are found to be sufficiently related that they can be considered members of the same genus or family. However, they bear only slight resemblance to 'typical' Procaryotic genera; such as Escherichia, Bacillus and Anacystis. The divergence of the methanogenic bacteria from other bacteria may be the most ancient phylogenetic event yet detected - antedating considerably the divergence of the blue green algal line for example, from the main bacterial line.

Influence of beam divergence on form-factor in X-ray diffraction radiation

International Nuclear Information System (INIS)

Sergeeva, D.Yu.; Tishchenko, A.A.; Strikhanov, M.N.

2015-01-01

Diffraction radiation from divergent beam is considered in terms of radiation in UV and X-ray range. Scedastic form of Gaussian distribution of the particle in the bunch, i.e. Gaussian distribution with changing dispersion has been used, which is more adequate for description of divergent beams than often used Gaussian distribution with constant dispersion. Both coherent and incoherent form-factors are taken into account. The conical diffraction effect in diffraction radiation is proved to make essential contribution in spectral-angular characteristics of radiation from a divergent beam

Intrinsic incompatibilities evolving as a by-product of divergent ecological selection: Considering them in empirical studies on divergence with gene flow.

Science.gov (United States)

Kulmuni, J; Westram, A M

2017-06-01

The possibility of intrinsic barriers to gene flow is often neglected in empirical research on local adaptation and speciation with gene flow, for example when interpreting patterns observed in genome scans. However, we draw attention to the fact that, even with gene flow, divergent ecological selection may generate intrinsic barriers involving both ecologically selected and other interacting loci. Mechanistically, the link between the two types of barriers may be generated by genes that have multiple functions (i.e., pleiotropy), and/or by gene interaction networks. Because most genes function in complex networks, and their evolution is not independent of other genes, changes evolving in response to ecological selection can generate intrinsic barriers as a by-product. A crucial question is to what extent such by-product barriers contribute to divergence and speciation-that is whether they stably reduce gene flow. We discuss under which conditions by-product barriers may increase isolation. However, we also highlight that, depending on the conditions (e.g., the amount of gene flow and the strength of selection acting on the intrinsic vs. the ecological barrier component), the intrinsic incompatibility may actually destabilize barriers to gene flow. In practice, intrinsic barriers generated as a by-product of divergent ecological selection may generate peaks in genome scans that cannot easily be interpreted. We argue that empirical studies on divergence with gene flow should consider the possibility of both ecological and intrinsic barriers. Future progress will likely come from work combining population genomic studies, experiments quantifying fitness and molecular studies on protein function and interactions. © 2017 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.

Viewpoint Environmental Slogans: Memes with Diverging ...

African Journals Online (AJOL)

Environmental slogans can be seen as memes, i.e. cultural constructs that, not unlike genes, replicate themselves from one generation to the next. Memes may, however, be divergently interpreted and some memes can even have unwanted side-effects. We wanted to find out how supporters of an environmental ...

Genetic Divergence in Sugarcane Genotypes

OpenAIRE

Tahir, Mohammad; Rahman, Hidayatur; Gul, Rahmani; Ali, Amjad; Khalid, Muhammad

2012-01-01

To assess genetic divergence of sugarcane germplasm, an experiment comprising 25 sugarcane genotypes was conducted at Sugar Crops Research Institute (SCRI), Mardan, Khyber Pakhtunkhwa, Pakistan, in quadruple lattice design during 2008-09. Among the 14 parameters evaluated, majority exhibited significant differences while some showed nonsignificant mean squares. The initial correlation matrix revealed medium to high correlations. Principal Component Analysis (PCA) showed that there were two pr...

Changes in cis-regulatory elements of a key floral regulator are associated with divergence of inflorescence architectures

NARCIS (Netherlands)

Kusters, E.; Della Pina, S.; Castel, R.; Souer, E.; Koes, R.

2015-01-01

Higher plant species diverged extensively with regard to the moment (flowering time) and position (inflorescence architecture) at which flowers are formed. This seems largely caused by variation in the expression patterns of conserved genes that specify floral meristem identity (FMI), rather than

Changes in cis-regulatory elements of a key floral regulator are associated with divergence of inflorescence architectures.

NARCIS (Netherlands)

Kusters, E.; Della Pina, S.; Castel, R.; Souer, E.J.; Koes, R.E.

2015-01-01

Higher plant species diverged extensively with regard to the moment (flowering time) and position (inflorescence architecture) at which flowers are formed. This seems largely caused by variation in the expression patterns of conserved genes that specify floral meristem identity (FMI), rather than

Divergence from factorizable distributions and matroid representations by partitions

Czech Academy of Sciences Publication Activity Database

Matúš, František

2009-01-01

Roč. 55, č. 12 (2009), s. 5375-5381 ISSN 0018-9448 R&D Projects: GA AV ČR IAA100750603; GA ČR GA201/04/0393 Institutional research plan: CEZ:AV0Z10750506 Keywords : Information divergence * relative entropy * Shannon entropy * exponential family * hierarchical model * log-linear model * contingency table * Gibbs distribution * matroid representation * secret sharing scheme * maximum likelihood. Subject RIV: BA - General Mathematics Impact factor: 2.357, year: 2009 http://library.utia.cas.cz/separaty/2009/MTR/matus-divergence from factorizable distributions and matroid representations by partitions.pdf

Development of Metarhizium anisopliae and Beauveria bassiana formulations for control of malaria mosquito larvae

NARCIS (Netherlands)

Bukhari, S.T.; Takken, W.; Koenraadt, C.J.M.

2011-01-01

Background The entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana have demonstrated effectiveness against anopheline larvae in the laboratory. However, utilising these fungi for the control of anopheline larvae under field conditions, relies on development of effective means of

Development of the BG-Malaria trap as an alternative to human-landing catches for the capture of Anopheles darlingi

Directory of Open Access Journals (Sweden)

Renata Antonaci Gama

2013-09-01

Full Text Available Although the human-landing catch (HLC method is the most effective for collecting anthropophilic anophelines, it has been increasingly abandoned, primarily for ethical considerations. The objective of the present study was to develop a new trap for the collection of Anopheles darlingi . The initial trials were conducted using the BG-Sentinel trap as a standard for further trap development based on colour, airflow direction and illumination. The performance of the trap was then compared with those of the CDC, Fay-Prince, counterflow geometry trap (CFG and HLC. All trials were conducted outdoors between 06:00 pm-08:00 pm. Female specimens of An. darlingi were dissected to determine their parity. A total of 8,334 anophelines were captured, of which 4,945 were identified as An. darlingi . The best trap configuration was an all-white version, with an upward airflow and no required light source. This configuration was subsequently named BG-Malaria (BGM. The BGM captured significantly more anophelines than any of the other traps tested and was similar to HLC with respect to the number and parity of anophelines. The BGM trap can be used as an alternative to HLC for collecting anophelines.

To be liked versus respected: Divergent goals in interracial interactions.

Science.gov (United States)

Bergsieker, Hilary B; Shelton, J Nicole; Richeson, Jennifer A

2010-08-01

Pervasive representations of Blacks and Latinos as unintelligent and of Whites as racist may give rise to divergent impression management goals in interracial interactions. We present studies showing that in interracial interactions racial minorities seek to be respected and seen as competent more than Whites do, whereas Whites seek to be liked and seen as moral more than racial minorities do. These divergent impression management goals are reflected in Whites' and racial minorities' self-report responses (Studies 1a, 1b, 2, and 4) and behaviors (Studies 3a and 3b). Divergent goals are observed in pre-existing relationships (Study 2), as well as in live interactions (Studies 3a, 3b, and 4), and are associated with higher levels of negative other-directed affect (Study 4). Implications of these goals for interracial communication and misunderstandings are discussed.

Engaging Students in Designing Movement: The Divergent Discovery Style of Teaching

Science.gov (United States)

Chatoupis, Constantine

2018-01-01

In the divergent discovery style of teaching the teacher designs problems that engage students in finding multiple solutions. The purpose of this article is to show how physical educators can use the divergent discovery style in the gymnasium. A brief description of this style and its connection to the SHAPE America National Standards for K-12…

Evaluating the relationship between evolutionary divergence and phylogenetic accuracy in AFLP data sets.

Science.gov (United States)

García-Pereira, María Jesús; Caballero, Armando; Quesada, Humberto

2010-05-01

Using in silico amplified fragment length polymorphism (AFLP) fingerprints, we explore the relationship between sequence similarity and phylogeny accuracy to test when, in terms of genetic divergence, the quality of AFLP data becomes too low to be informative for a reliable phylogenetic reconstruction. We generated DNA sequences with known phylogenies using balanced and unbalanced trees with recent, uniform and ancient radiations, and average branch lengths (from the most internal node to the tip) ranging from 0.02 to 0.4 substitutions per site. The resulting sequences were used to emulate the AFLP procedure. Trees were estimated by maximum parsimony (MP), neighbor-joining (NJ), and minimum evolution (ME) methods from both DNA sequences and virtual AFLP fingerprints. The estimated trees were compared with the reference trees using a score that measures overall differences in both topology and relative branch length. As expected, the accuracy of AFLP-based phylogenies decreased dramatically in the more divergent data sets. Above a divergence of approximately 0.05, AFLP-based phylogenies were largely inaccurate irrespective of the distinct topology, radiation model, or phylogenetic method used. This value represents an upper bound of expected tree accuracy for data sets with a simple divergence history; AFLP data sets with a similar divergence but with unbalanced topologies and short ancestral branches produced much less accurate trees. The lack of homology of AFLP bands quickly increases with divergence and reaches its maximum value (100%) at a divergence of only 0.4. Low guanine-cytosine (GC) contents increase the number of nonhomologous bands in AFLP data sets and lead to less reliable trees. However, the effect of the lack of band homology on tree accuracy is surprisingly small relative to the negative impact due to the low information content of AFLP characters. Tree-building methods based on genetic distance displayed similar trends and outperformed parsimony

Selection from parasites favours immunogenetic diversity but not divergence among locally adapted host populations.

Science.gov (United States)

Tobler, M; Plath, M; Riesch, R; Schlupp, I; Grasse, A; Munimanda, G K; Setzer, C; Penn, D J; Moodley, Y

2014-05-01

The unprecedented polymorphism in the major histocompatibility complex (MHC) genes is thought to be maintained by balancing selection from parasites. However, do parasites also drive divergence at MHC loci between host populations, or do the effects of balancing selection maintain similarities among populations? We examined MHC variation in populations of the livebearing fish Poecilia mexicana and characterized their parasite communities. Poecilia mexicana populations in the Cueva del Azufre system are locally adapted to darkness and the presence of toxic hydrogen sulphide, representing highly divergent ecotypes or incipient species. Parasite communities differed significantly across populations, and populations with higher parasite loads had higher levels of diversity at class II MHC genes. However, despite different parasite communities, marked divergence in adaptive traits and in neutral genetic markers, we found MHC alleles to be remarkably similar among host populations. Our findings indicate that balancing selection from parasites maintains immunogenetic diversity of hosts, but this process does not promote MHC divergence in this system. On the contrary, we suggest that balancing selection on immunogenetic loci may outweigh divergent selection causing divergence, thereby hindering host divergence and speciation. Our findings support the hypothesis that balancing selection maintains MHC similarities among lineages during and after speciation (trans-species evolution). © 2014 The Authors. Journal of Evolutionary Biology © 2014 European Society For Evolutionary Biology.

the use of larvaoils for the eradication of the malaria vector

African Journals Online (AJOL)

CHOSENPC

tension, spreading diameter on water surface and extermination time. Five blends A:B (Kerosene: ... irritating biting pests (Harwood and James, 1979). Mosquitoes lay their ... water serve as breeding sites for Aedes aegypti not the Anopheline ...

Minimization and parameter estimation for seminorm regularization models with I-divergence constraints

International Nuclear Information System (INIS)

Teuber, T; Steidl, G; Chan, R H

2013-01-01

In this paper, we analyze the minimization of seminorms ‖L · ‖ on R n under the constraint of a bounded I-divergence D(b, H · ) for rather general linear operators H and L. The I-divergence is also known as Kullback–Leibler divergence and appears in many models in imaging science, in particular when dealing with Poisson data but also in the case of multiplicative Gamma noise. Often H represents, e.g., a linear blur operator and L is some discrete derivative or frame analysis operator. A central part of this paper consists in proving relations between the parameters of I-divergence constrained and penalized problems. To solve the I-divergence constrained problem, we consider various first-order primal–dual algorithms which reduce the problem to the solution of certain proximal minimization problems in each iteration step. One of these proximation problems is an I-divergence constrained least-squares problem which can be solved based on Morozov’s discrepancy principle by a Newton method. We prove that these algorithms produce not only a sequence of vectors which converges to a minimizer of the constrained problem but also a sequence of parameters which converges to a regularization parameter so that the corresponding penalized problem has the same solution. Furthermore, we derive a rule for automatically setting the constraint parameter for data corrupted by multiplicative Gamma noise. The performance of the various algorithms is finally demonstrated for different image restoration tasks both for images corrupted by Poisson noise and multiplicative Gamma noise. (paper)

Genetic divergence among interspecific Paspalum hybrids based on seed production traits

Directory of Open Access Journals (Sweden)

Rodrigo Ramos Lopes

Full Text Available ABSTRACT The use of genetic divergence as a basis for identifying superior individuals, with greater heterozygosity, is important in view of the difficulty when selecting of dissimilar genotypes exhibiting high average for interest traits. The aim of this study was to evaluate the genetic divergence and the expression of seed production traits in seventeen apomictic Paspalum plicatulum × Paspalum guenoarum hybrids and two male parents (P. guenoarum. A randomized block design was used, with genotypes individually arranged into ten blocks. The following traits were assessed: total number of tillers/plant (TT, reproductive tiller/plant (RT, number of racemes per inflorescence (NRI, reproductive tiller height (RTH, inflorescence rachis length (IRL, number of seeds/inflorescence (NSI, weight of a thousand seeds (WTS and seed production (SP. Genetic divergence among the genotypes was estimated using the Tocher method and UPGMA clustering, based on the generalized Mahalanobis distance (D2 ii’. The Tocher and UPGMA optimization methods showed high concordance. The traits that most contributed to genetic divergence were RTH (23.59%, IRL (21.63%, WTS (16.67% and SP (14.23%. The presence of genetic diversity made it possible to identify divergent genotypes and those with high means for the traits studied, allowing the selection of genotypes with significant breeding potential. Repeated cross-breeding of female superior plants with the genotypes Azulão and H20 can result in a high heterosis effect on seed production characteristics.

Demographic histories of adaptively diverged riparian and non-riparian species of Ainsliaea (Asteraceae) inferred from coalescent analyses using multiple nuclear loci.

Science.gov (United States)

Mitsui, Yuki; Setoguchi, Hiroaki

2012-12-28

Understanding demographic histories, such as divergence time, patterns of gene flow, and population size changes, in ecologically diverging lineages provide implications for the process and maintenance of population differentiation by ecological adaptation. This study addressed the demographic histories in two independently derived lineages of flood-resistant riparian plants and their non-riparian relatives [Ainsliaea linearis (riparian) and A. apiculata (non-riparian); A. oblonga (riparian) and A. macroclinidioides (non-riparian); Asteraceae] using an isolation-with-migration (IM) model based on variation at 10 nuclear DNA loci. The highest posterior probabilities of the divergence time parameters were estimated to be ca. 25,000 years ago for A. linearis and A. apiculata and ca. 9000 years ago for A. oblonga and A. macroclinidioides, although the confidence intervals of the parameters had broad ranges. The likelihood ratio tests detected evidence of historical gene flow between both riparian/non-riparian species pairs. The riparian populations showed lower levels of genetic diversity and a significant reduction in effective population sizes compared to the non-riparian populations and their ancestral populations. This study showed the recent origins of flood-resistant riparian plants, which are remarkable examples of plant ecological adaptation. The recent divergence and genetic signatures of historical gene flow among riparian/non-riparian species implied that they underwent morphological and ecological differentiation within short evolutionary timescales and have maintained their species boundaries in the face of gene flow. Comparative analyses of adaptive divergence in two sets of riparian/non-riparian lineages suggested that strong natural selection by flooding had frequently reduced the genetic diversity and size of riparian populations through genetic drift, possibly leading to fixation of adaptive traits in riparian populations. The two sets of riparian

Two families of astrophysical diverging lens models

Science.gov (United States)

Er, Xinzhong; Rogers, Adam

2018-03-01

In the standard gravitational lensing scenario, rays from a background source are bent in the direction of a foreground lensing mass distribution. Diverging lens behaviour produces deflections in the opposite sense to gravitational lensing, and is also of astrophysical interest. In fact, diverging lensing due to compact distributions of plasma has been proposed as an explanation for the extreme scattering events that produce frequency-dependent dimming of extragalactic radio sources, and may also be related to the refractive radio wave phenomena observed to affect the flux density of pulsars. In this work we study the behaviour of two families of astrophysical diverging lenses in the geometric optics limit, the power law, and the exponential plasma lenses. Generally, the members of these model families show distinct behaviour in terms of image formation and magnification, however the inclusion of a finite core for certain power-law lenses can produce a caustic and critical curve morphology that is similar to the well-studied Gaussian plasma lens. Both model families can produce dual radial critical curves, a novel distinction from the tangential distortion usually produced by gravitational (converging) lenses. The deflection angle and magnification of a plasma lens vary with the observational frequency, producing wavelength-dependent magnifications that alter the amplitudes and the shape of the light curves. Thus, multiwavelength observations can be used to physically constrain the distribution of the electron density in such lenses.

A divergence theorem for pseudo-Finsler spaces

OpenAIRE

Minguzzi, E.

2015-01-01

We study the divergence theorem on pseudo-Finsler spaces and obtain a completely Finslerian version for spaces having a vanishing mean Cartan torsion. This result helps to clarify the problem of energy-momentum conservation in Finsler gravity theories.

Evidence for Divergent Evolution of Growth Temperature Preference in Sympatric Saccharomyces Species

Science.gov (United States)

Gonçalves, Paula; Valério, Elisabete; Correia, Cláudia; de Almeida, João M. G. C. F.; Sampaio, José Paulo

2011-01-01

The genus Saccharomyces currently includes eight species in addition to the model yeast Saccharomyces cerevisiae, most of which can be consistently isolated from tree bark and soil. We recently found sympatric pairs of Saccharomyces species, composed of one cryotolerant and one thermotolerant species in oak bark samples of various geographic origins. In order to contribute to explain the occurrence in sympatry of Saccharomyces species, we screened Saccharomyces genomic data for protein divergence that might be correlated to distinct growth temperature preferences of the species, using the dN/dS ratio as a measure of protein evolution rates and pair-wise species comparisons. In addition to proteins previously implicated in growth at suboptimal temperatures, we found that glycolytic enzymes were among the proteins exhibiting higher than expected divergence when one cryotolerant and one thermotolerant species are compared. By measuring glycolytic fluxes and glycolytic enzymatic activities in different species and at different temperatures, we subsequently show that the unusual divergence of glycolytic genes may be related to divergent evolution of the glycolytic pathway aligning its performance to the growth temperature profiles of the different species. In general, our results support the view that growth temperature preference is a trait that may have undergone divergent selection in the course of ecological speciation in Saccharomyces. PMID:21674061

Relations between heat exchange and Rényi divergences

Science.gov (United States)

Wei, Bo-Bo

2018-04-01

In this work, we establish an exact relation which connects the heat exchange between two systems initialized in their thermodynamic equilibrium states at different temperatures and the Rényi divergences between the initial thermodynamic equilibrium state and the final nonequilibrium state of the total system. The relation tells us that the various moments of the heat statistics are determined by the Renyi divergences between the initial equilibrium state and the final nonequilibrium state of the global system. In particular the average heat exchange is quantified by the relative entropy between the initial equilibrium state and the final nonequilibrium state of the global system. The relation is applicable to both finite classical systems and finite quantum systems.

High temperature phase transitions without infrared divergences

International Nuclear Information System (INIS)

Tetradis, N.; Wetterich, C.

1993-09-01

The most commonly used method for the study of high temperature phase transitions is based on the perturbative evaluation of the temperature dependent effective potential. This method becomes unreliable in the case of a second order or weakly first order phase transition, due to the appearance of infrared divergences. These divergences can be controlled through the method of the effective average action which employs renormalization group ideas. We report on the study of the high temperature phase transition for the N-component φ 4 theory. A detailed quantitative picture of the second order phase transition is presented, including the critical exponents for the behaviour in the vicinity of the critical temperature. An independent check of the results is obtained in the large N limit, and contact with the perturbative approach is established through the study of the Schwinger-Dyson equations. (orig.)

Hypergeometric continuation of divergent perturbation series: I. Critical exponents of the Bose–Hubbard model

International Nuclear Information System (INIS)

Sanders, Sören; Holthaus, Martin

2017-01-01

We study the connection between the exponent of the order parameter of the Mott insulator-to-superfluid transition occurring in the two-dimensional Bose–Hubbard model, and the divergence exponents of its one- and two-particle correlation functions. We find that at the multicritical points all divergence exponents are related to each other, allowing us to express the critical exponent in terms of one single divergence exponent. This approach correctly reproduces the critical exponent of the three-dimensional XY universality class. Because divergence exponents can be computed in an efficient manner by hypergeometric analytic continuation, our strategy is applicable to a wide class of systems. (paper)

Hypergeometric continuation of divergent perturbation series: I. Critical exponents of the Bose-Hubbard model

Science.gov (United States)

Sanders, Sören; Holthaus, Martin

2017-10-01

We study the connection between the exponent of the order parameter of the Mott insulator-to-superfluid transition occurring in the two-dimensional Bose-Hubbard model, and the divergence exponents of its one- and two-particle correlation functions. We find that at the multicritical points all divergence exponents are related to each other, allowing us to express the critical exponent in terms of one single divergence exponent. This approach correctly reproduces the critical exponent of the three-dimensional XY universality class. Because divergence exponents can be computed in an efficient manner by hypergeometric analytic continuation, our strategy is applicable to a wide class of systems.

Rigid-body rotation of an electron cloud in divergent magnetic fields

International Nuclear Information System (INIS)

Fruchtman, A.; Gueroult, R.; Fisch, N. J.

2013-01-01

For a given voltage across a divergent poloidal magnetic field, two electric potential distributions, each supported by a rigid-rotor electron cloud rotating with a different frequency, are found analytically. The two rotation frequencies correspond to the slow and fast rotation frequencies known in uniform plasma. Due to the centrifugal force, the equipotential surfaces, that correspond to the two electric potential distributions, diverge more than the magnetic surfaces do, the equipotential surfaces in the fast mode diverge largely in particular. The departure of the equipotential surfaces from the magnetic field surfaces may have a significant focusing effect on the ions accelerated by the electric field. The focusing effect could be important for laboratory plasma accelerators as well as for collimation of astrophysical jets

Extensive behavioural divergence following colonisation of the freshwater environment in threespine sticklebacks.

Directory of Open Access Journals (Sweden)

Carole Di-Poi

Full Text Available Colonisation of novel environments means facing new ecological challenges often resulting in the evolution of striking divergence in phenotypes. However, little is known about behavioural divergence following colonisation, despite the predicted importance of the role of behavioural phenotype-environment associations in adaptive divergence. We studied the threespine stickleback (Gasterosteus aculeatus, a model system for postglacial colonisation of freshwater habitats largely differing in ecological conditions from the ones faced by the descendants of the marine ancestor. We found that common-environment reared freshwater juveniles were less social, more active and more aggressive than their marine counterparts. This behavioural divergence could represent the result of natural selection that acted on individuals following freshwater colonisation, with predation as a key selection agent. Alternatively, the behavioural profile of freshwater juveniles could represent the characteristics of individuals that preferentially invaded freshwater after the glacial retreat, drawn from the standing variation present in the marine population.

The direct Flow parametric Proof of Gauss' Divergence Theorem revisited

OpenAIRE

Markvorsen, Steen

2006-01-01

The standard proof of the divergence theorem in undergraduate calculus courses covers the theorem for static domains between two graph surfaces. We show that within first year undergraduate curriculum, the flow proof of the dynamic version of the divergence theorem - which is usually considered only much later in more advanced math courses - is comprehensible with only a little extension of the first year curriculum. Moreover, it is more intuitive than the static proof. We support this intuit...

Divergent Priors and well Behaved Bayes Factors

NARCIS (Netherlands)

R.W. Strachan (Rodney); H.K. van Dijk (Herman)

2011-01-01

textabstractDivergent priors are improper when defined on unbounded supports. Bartlett's paradox has been taken to imply that using improper priors results in ill-defined Bayes factors, preventing model comparison by posterior probabilities. However many improper priors have attractive properties

Laughter and the Management of Divergent Positions in Peer Review Interactions

Science.gov (United States)

Raclaw, Joshua; Ford, Cecilia E.

2017-01-01

In this paper we focus on how participants in peer review interactions use laughter as a resource as they publicly report divergence of evaluative positions, divergence that is typical in the give and take of joint grant evaluation. Using the framework of conversation analysis, we examine the infusion of laughter and multimodal laugh-relevant practices into sequences of talk in meetings of grant reviewers deliberating on the evaluation and scoring of high-level scientific grant applications. We focus on a recurrent sequence in these meetings, what we call the score-reporting sequence, in which the assigned reviewers first announce the preliminary scores they have assigned to the grant. We demonstrate that such sequences are routine sites for the use of laugh practices to navigate the initial moments in which divergence of opinion is made explicit. In the context of meetings convened for the purposes of peer review, laughter thus serves as a valuable resource for managing the socially delicate but institutionally required reporting of divergence and disagreement that is endemic to meetings where these types of evaluative tasks are a focal activity. PMID:29170594

Deep phylogeographic divergence and cytonuclear discordance in the grasshopper Oedaleus decorus.

Science.gov (United States)

Kindler, Eveline; Arlettaz, Raphaël; Heckel, Gerald

2012-11-01

The grasshopper Oedaleus decorus is a thermophilic insect with a large, mostly south-Palaearctic distribution range, stretching from the Mediterranean regions in Europe to Central-Asia and China. In this study, we analyzed the extent of phylogenetic divergence and the recent evolutionary history of the species based on 274 specimens from 26 localities across the distribution range in Europe. Phylogenetic relationships were determined using sequences of two mitochondrial loci (ctr, ND2) with neighbour-joining and Bayesian methods. Additionally, genetic differentiation was analyzed based on mitochondrial DNA and 11 microsatellite markers using F-statistics, model-free multivariate and model-based Bayesian clustering approaches. Phylogenetic analyses detected consistently two highly divergent, allopatrically distributed lineages within O. decorus. The divergence among these Western and Eastern lineages meeting in the region of the Alps was similar to the divergence of each lineage to the sister species O. asiaticus. Genetic differentiation for ctr was extremely high between Western and Eastern grasshopper populations (F(ct)=0.95). Microsatellite markers detected much lower but nevertheless very significant genetic structure among population samples. The nuclear data also demonstrated a case of cytonuclear discordance because the affiliation with mitochondrial lineages was incongruent in Northern Italy. Taken together these results provide evidence of an ancient separation within Oedaleus and either historical introgression of mtDNA among lineages and/or ongoing sex-specific gene flow in this grasshopper. Our study stresses the importance of multilocus approaches for unravelling the history and status of taxa of uncertain evolutionary divergence. Copyright © 2012 Elsevier Inc. All rights reserved.

Divergent primary moult-A rare moult sequence among Western Palaearctic passerines.

Directory of Open Access Journals (Sweden)

Yosef Kiat

Full Text Available Wing morphology strongly affects flight performance which may consequently decline during feather moult due to the creation of feather gaps in the wing. Hence, the size and shape of moult-related wing gap may directly affect flight capacity. Here I examined the rare divergent primary moult sequence compared to the more common descendant moult sequence. In the divergent moult, the focus of primary moult is shifted from P1 (primary feather numbered descendantly to another primary between P2 and P5, and then primaries are moulted in two concurrent waves, one descendant and the other ascendant. The result of this rare moult sequence is the splitting of the wing gap to two smaller gaps. Using a large moult database including 6,763 individuals of 32 Western Palaearctic passerine species, I found evidence of divergent moult only among 27 individuals of 12 species. I examined the speed of wing-feather moult for each individual that moulted divergently compared to a control group of individuals at the same moult stage which moulted following the common descending sequence. The results indicate that the sequence of primary moult and moult speed are correlated. Individuals which moulted divergently moulted their primaries with higher moult speed than descendant moulters. The applicability of this study is weakened by the dearth of moult data, thus making it difficult to draw conclusions for a large range of species. Ornithologists and bird ringers are therefore encouraged to collect more basic moult data during their field study.

AlignMiner: a Web-based tool for detection of divergent regions in multiple sequence alignments of conserved sequences

Directory of Open Access Journals (Sweden)

Claros M Gonzalo

2010-06-01

to reliably detect divergent regions via several scoring methods that provide different levels of selectivity. Its predictions have been verified by experimental means. Hence, it is expected that its usage will save researchers' time and ensure an objective selection of the best-possible divergent region when closely related sequences are analysed. AlignMiner is freely available at http://www.scbi.uma.es/alignminer.

Summation of Divergent Series and Zeldovich's Regularization Method

International Nuclear Information System (INIS)

Mur, V.D.; Pozdnyakov, S.G.; Popruzhenko, S.V.; Popov, V.S.

2005-01-01

A method for summing divergent series, including perturbation-theory series, is considered. This method is an analog of Zeldovich's regularization method in the theory of quasistationary states. It is shown that the method in question is more powerful than the well-known Abel and Borel methods, but that it is compatible with them (that is, it leads to the same value for the sum of a series). The constraints on the parameter domain that arise upon the removal of the regularization of divergent integrals by this method are discussed. The dynamical Stark shifts and widths of loosely bound s states in the field of a circularly polarized electromagnetic wave are calculated at various values of the Keldysh adiabaticity parameter and the multiquantum parameter

Genetic surfing, not allopatric divergence, explains spatial sorting of mitochondrial haplotypes in venomous coralsnakes.

Science.gov (United States)

Streicher, Jeffrey W; McEntee, Jay P; Drzich, Laura C; Card, Daren C; Schield, Drew R; Smart, Utpal; Parkinson, Christopher L; Jezkova, Tereza; Smith, Eric N; Castoe, Todd A

2016-07-01

Strong spatial sorting of genetic variation in contiguous populations is often explained by local adaptation or secondary contact following allopatric divergence. A third explanation, spatial sorting by stochastic effects of range expansion, has been considered less often though theoretical models suggest it should be widespread, if ephemeral. In a study designed to delimit species within a clade of venomous coralsnakes, we identified an unusual pattern within the Texas coral snake (Micrurus tener): strong spatial sorting of divergent mitochondrial (mtDNA) lineages over a portion of its range, but weak sorting of these lineages elsewhere. We tested three alternative hypotheses to explain this pattern-local adaptation, secondary contact following allopatric divergence, and range expansion. Collectively, near panmixia of nuclear DNA, the signal of range expansion associated sampling drift, expansion origins in the Gulf Coast of Mexico, and species distribution modeling suggest that the spatial sorting of divergent mtDNA lineages within M. tener has resulted from genetic surfing of standing mtDNA variation-not local adaptation or allopatric divergence. Our findings highlight the potential for the stochastic effects of recent range expansion to mislead estimations of population divergence made from mtDNA, which may be exacerbated in systems with low vagility, ancestral mtDNA polymorphism, and male-biased dispersal. © 2016 The Author(s).

Divergence in technical efficiency of electric utilities: Evidence from the SAPP

International Nuclear Information System (INIS)

Jaunky, Vishal Chandr

2013-01-01

This paper investigates the convergence pattern of technical efficiency of the South Africa Power Pool (SAPP) utilities over the period April 2003–March 2010 by means of parametric and non-parametric techniques. Technical efficiency scores are computed via both stochastic frontier analysis and data envelopment analysis. Mixed results are obtained from the neoclassical convergence approaches. In addition, distribution dynamics methods reveal some evidence of club-formation and this result is supported with the occurrence of γ-divergence. Taken as a whole, technical efficiency is found to diverge among the utilities operating in the power pool. -- Highlights: •The technical efficiency convergence pattern within the South Africa Power Pool is assessed. •Mixed results are obtained from the parametric neoclassical convergence approaches. •Evidence of divergence is revealed by the non-parametric convergence approaches

On divergence of finite measures and their applicability in statistics and information theory

Czech Academy of Sciences Publication Activity Database

Vajda, Igor; Stummer, W.

2009-01-01

Roč. 44, č. 2 (2009), s. 169-187 ISSN 0233-1888 R&D Projects: GA MŠk(CZ) 1M0572; GA ČR(CZ) GA102/07/1131 Institutional research plan: CEZ:AV0Z10750506 Keywords : Local and global divergences of finite measures * Divergences of sigma-finite measures * Statistical censoring * Pinsker's inequality, Ornstein's distance * Differential power entropies Subject RIV: BD - Theory of Information Impact factor: 0.759, year: 2009 http://library.utia.cas.cz/separaty/2009/SI/vajda-on divergence of finite measures and their applicability in statistics and information theory.pdf

A Multiparameter Network Reveals Extensive Divergence between C. elegans bHLH Transcription Factors

DEFF Research Database (Denmark)

Grove, C.; De Masi, Federico; Newburger, Daniel

2009-01-01

parameters remain undetermined. We comprehensively identify dimerization partners, spatiotemporal expression patterns, and DNA-binding specificities for the C. elegans bHLH family of TFs, and model these data into an integrated network. This network displays both specificity and promiscuity, as some b......HLH proteins, DNA sequences, and tissues are highly connected, whereas others are not. By comparing all bHLH TFs, we find extensive divergence and that all three parameters contribute equally to bHLH divergence. Our approach provides a framework for examining divergence for other protein families in C. elegans...

Bjorken-Johnson-Low analysis of commutator anomalies, current-divergence anomalies, and Fujikawa's relation in chiral gauge theories

International Nuclear Information System (INIS)

Seo, K.

1990-01-01

Fermion one-loop corrections to the commutators of the gauge field, the electric field, and the charge density with the total Hamiltonian are evaluated by the Bjorken-Johnson-Low method in chiral gauge theories. It turns out that individual terms of the Hamiltonian give anomalous terms to the commutator with the electric field, but the total Hamiltonian does not. That is, the classical equation of motion for the electric field holds as the Heisenberg equation. The current-divergence anomaly is identified with the anomalous terms of the commutator between the charge density and the total Hamiltonian. These two results are combined to show that the time derivative of the Gauss-law operator amounts to the current-divergence anomaly (Fujikawa's relation)

Divergence, recombination and retention of functionality during protein evolution

Directory of Open Access Journals (Sweden)

Xu Yanlong O

2005-09-01

Full Text Available Abstract We have only a vague idea of precisely how protein sequences evolve in the context of protein structure and function. This is primarily because structural and functional contexts are not easily predictable from the primary sequence, and evaluating patterns of evolution at individual residue positions is also difficult. As a result of increasing biodiversity in genomics studies, progress is being made in detecting context-dependent variation in substitution processes, but it remains unclear exactly what context-dependent patterns we should be looking for. To address this, we have been simulating protein evolution in the context of structure and function using lattice models of proteins and ligands (or substrates. These simulations include thermodynamic features of protein stability and population dynamics. We refer to this approach as 'ab initio evolution' to emphasise the fact that the equilibrium details of fitness distributions arise from the physical principles of the system and not from any preconceived notions or arbitrary mathematical distributions. Here, we present results on the retention of functionality in homologous recombinants following population divergence. A central result is that protein structure characteristics can strongly influence recombinant functionality. Exceptional structures with many sequence options evolve quickly and tend to retain functionality -- even in highly diverged recombinants. By contrast, the more common structures with fewer sequence options evolve more slowly, but the fitness of recombinants drops off rapidly as homologous proteins diverge. These results have implications for understanding viral evolution, speciation and directed evolutionary experiments. Our analysis of the divergence process can also guide improved methods for accurately approximating folding probabilities in more complex but realistic systems.

Limit sets and global dynamic for 2-D divergence-free vector fields

International Nuclear Information System (INIS)

Marzougui, H.

2004-08-01

T. Ma and S. Wang studied the global structure of regular divergence-free vector fields on compact surfaces with or without boundary. This paper extends their study to the general case of divergence-free vector fields (regular or not) on closed surfaces and gives as a consequence a simple proof of their results. (author)

Evolutionary divergence in sexual signals: Insights from within and among barn swallow populations

Science.gov (United States)

Wilkins, Matthew Reed

A wealth of studies across diverse animal groups indicate the importance of sexual selection in shaping phenotypes within and across breeding populations. In recent decades, much research has focused on how divergent sexual selection pressures among populations may lead to speciation. For my first dissertation chapter, I performed a literature review on the causes and consequences of evolutionary divergence in acoustic signals and developed the acoustic window conceptual framework for understanding the contributions of selection, genetic drift, and evolutionary constraint to signal divergence. Further, I found that sexual selection explains acoustic differences between recently diverged populations of the best-studied taxa. However, the relative contributions of ecological selection, sexual selection, and drift to acoustic divergence have not typically been considered within the same study systems. The remainder of my dissertation used the Northern Hemisphere-distributed barn swallow ( Hirundo rustica) species complex as a model system to study sender-receiver dynamics, intra- and intersexual selection pressures, and visual and acoustic signal interactions at the local scale, and signal divergence across populations at the global scale. From song recordings taken across 19 sampling sites, spanning five of six described subspecies, I demonstrated considerable conservation in song structure. However, temporal traits were highly divergent across subspecies, and in particular, the speed of the terminal trill of songs. In a detailed study of the multimodal communication system of the barn swallow (including visual and acoustic traits), I demonstrated that males and females use different types of signals to mediate competition and mate choice. One of the only exceptions to this rule was trill rate, which was also implicated in song divergence across populations. In order to test the function of trill rate in communication, I performed a two-year playback study within the

Maximum one-shot dissipated work from Rényi divergences

Science.gov (United States)

Yunger Halpern, Nicole; Garner, Andrew J. P.; Dahlsten, Oscar C. O.; Vedral, Vlatko

2018-05-01

Thermodynamics describes large-scale, slowly evolving systems. Two modern approaches generalize thermodynamics: fluctuation theorems, which concern finite-time nonequilibrium processes, and one-shot statistical mechanics, which concerns small scales and finite numbers of trials. Combining these approaches, we calculate a one-shot analog of the average dissipated work defined in fluctuation contexts: the cost of performing a protocol in finite time instead of quasistatically. The average dissipated work has been shown to be proportional to a relative entropy between phase-space densities, to a relative entropy between quantum states, and to a relative entropy between probability distributions over possible values of work. We derive one-shot analogs of all three equations, demonstrating that the order-infinity Rényi divergence is proportional to the maximum possible dissipated work in each case. These one-shot analogs of fluctuation-theorem results contribute to the unification of these two toolkits for small-scale, nonequilibrium statistical physics.

Trends and Divergences in Childhood Income Dynamics, 1970-2010.

Science.gov (United States)

Hill, Heather D

2018-01-01

Earnings and income variability have increased since the 1970s, particularly at the bottom of the income distribution. Considerable evidence suggests that childhood income levels-captured as average or point-in-time yearly income-are associated with numerous child and adult outcomes. The importance to child development of stable proximal processes during childhood suggests that income variability may also be important, particularly if it is unpredictable, unintentional, or does not reflect an upward trend in family income. Using the Panel Study of Income Dynamics, this study documents trends since the 1970s in three dimensions of childhood income dynamics: level, variability, and growth (n=7991). The analysis reveals that income variability during childhood has grown over time, while income growth rates have not. In addition, the economic context of childhood has diverged substantially by socioeconomic status, race, and family structure, with the most disadvantaged children facing a double-whammy of low income and high variability. © 2018 Elsevier Inc. All rights reserved.

The constancy of gene conservation across divergent bacterial orders

Directory of Open Access Journals (Sweden)

Ackermann Martin

2009-01-01

Full Text Available Abstract Background Orthologous genes are frequently presumed to perform similar functions. However, outside of model organisms, this is rarely tested. One means of inferring changes in function is if there are changes in the level of gene conservation and selective constraint. Here we compare levels of gene conservation across three bacterial groups to test for changes in gene functionality. Findings The level of gene conservation for different orthologous genes is highly correlated across clades, even for highly divergent groups of bacteria. These correlations do not arise from broad differences in gene functionality (e.g. informational genes vs. metabolic genes, but instead seem to result from very specific differences in gene function. Furthermore, these functional differences appear to be maintained over very long periods of time. Conclusion These results suggest that even over broad time scales, most bacterial genes are under a nearly constant level of purifying selection, and that bacterial evolution is thus dominated by selective and functional stasis.

On the summability of divergent power series solutions for certain first-order linear PDEs

Directory of Open Access Journals (Sweden)

Masaki Hibino

2015-01-01

Full Text Available This article is concerned with the study of the Borel summability of divergent power series solutions for certain singular first-order linear partial differential equations of nilpotent type. Our main purpose is to obtain conditions which coefficients of equations should satisfy in order to ensure the Borel summability of divergent solutions. We will see that there is a close affinity between the Borel summability of divergent solutions and global analytic continuation properties for coefficients of equations.

Three Types of Flower Structures in a Divergent-Wrench Fault Zone

Science.gov (United States)

Huang, Lei; Liu, Chi-yang

2017-12-01

Flower structures are typical features of wrench fault zones. In conventional studies, two distinct kinds of flower structures have been identified based on differences in their internal structural architecture: (1) negative flower structures characterized by synforms and normal separations and (2) positive flower structures characterized by antiforms and reverse separations. In addition to negative and positive flower structures, in this study, a third kind of flower structure was identified in a divergent-wrench fault zone, a hybrid characterized by both antiforms and normal separations. Negative flower structures widely occur in divergent-wrench fault zones, and their presence indicates the combined effects of extensional and strike-slip motion. In contrast, positive and hybrid flower structures occur only in fault restraining bends and step overs. A hybrid flower structure can be considered as product of a kind of structural deformation typical of divergent-wrench zones; it is the result of the combined effects of extensional, compressional, and strike-slip strains under a locally appropriate compressional environment. The strain situation in it represents the transition stage that in between positive and negative flower structures. Kinematic and dynamic characteristics of the hybrid flower structures indicate the salient features of structural deformation in restraining bends and step overs along divergent-wrench faults, including the coexistence of three kinds of strains (i.e., compression, extension, and strike-slip) and synchronous presence of compressional (i.e., typical fault-bend fold) and extensional (normal faults) deformation in the same place. Hybrid flower structures are also favorable for the accumulation of hydrocarbons because of their special structural configuration in divergent-wrench fault zones.

Water transparency drives intra-population divergence in Eurasian Perch (Perca fluviatilis).

Science.gov (United States)

Bartels, Pia; Hirsch, Philipp E; Svanbäck, Richard; Eklöv, Peter

2012-01-01

Trait combinations that lead to a higher efficiency in resource utilization are important drivers of divergent natural selection and adaptive radiation. However, variation in environmental features might constrain foraging in complex ways and therefore impede the exploitation of critical resources. We tested the effect of water transparency on intra-population divergence in morphology of Eurasian perch (Perca fluviatilis) across seven lakes in central Sweden. Morphological divergence between near-shore littoral and open-water pelagic perch substantially increased with increasing water transparency. Reliance on littoral resources increased strongly with increasing water transparency in littoral populations, whereas littoral reliance was not affected by water transparency in pelagic populations. Despite the similar reliance on pelagic resources in pelagic populations along the water transparency gradient, the utilization of particular pelagic prey items differed with variation in water transparency in pelagic populations. Pelagic perch utilized cladocerans in lakes with high water transparency and copepods in lakes with low water transparency. We suggest that under impaired visual conditions low utilization of littoral resources by littoral perch and utilization of evasive copepods by pelagic perch may lead to changes in morphology. Our findings indicate that visual conditions can affect population divergence in predator populations through their effects on resource utilization.

Host-driven divergence in the parasitic plant Orobanche minor Sm. (Orobanchaceae).

Science.gov (United States)

Thorogood, C J; Rumsey, F J; Harris, S A; Hiscock, S J

2008-10-01

Many parasitic angiosperms have a broad host range and are therefore considered to be host generalists. Orobanche minor is a nonphotosynthetic root parasite that attacks a range of hosts from taxonomically disparate families. In the present study, we show that O. minor sensu lato may comprise distinct, genetically divergent races isolated by the different ecologies of their hosts. Using a three-pronged approach, we tested the hypothesis that intraspecific taxa O. minor var. minor and O. minor ssp. maritima parasitizing either clover (Trifolium pratense) or sea carrot (Daucus carota ssp.gummifer), respectively, are in allopatric isolation. Morphometric analysis revealed evidence of divergence but this was insufficient to define discrete, host-specific taxa. Intersimple sequence repeat (ISSR) marker-based data provided stronger evidence of divergence, suggesting that populations were isolated from gene flow. Phylogenetic analysis, using sequence-characterized amplified region (SCAR) markers derived from ISSR loci, provided strong evidence for divergence by clearly differentiating sea carrot-specific clades and mixed-host clades. Low levels of intrapopulation SCAR marker sequence variation and floral morphology suggest that populations on different hosts are probably selfing and inbreeding. Morphologically cryptic Orobanche taxa may therefore be isolated from gene flow by host ecology. Together, these data suggest that host specificity may be an important driver of allopatric speciation in parasitic plants.

Conversion of isotropic fluorescence into a long-range non-diverging beam

Science.gov (United States)

Zhang, Douguo; Zhu, Liangfu; Chen, Junxue; Wang, Ruxue; Wang, Pei; Ming, Hai; Badugu, Ramachandram; Rosenfeld, Mary; Zhan, Qiwen; Kuang, Cuifang; Liu, Xu; Lakowicz, Joseph R.

2018-04-01

Fluorescent samples typically emit isotropically in all directions. Large lenses and other optical components are needed to capture a significant fraction of the emission, and complex confocal microscopes are required for high resolution focal-plane imaging. It is known that Bessel beams have remarkable properties of being able to travel over long distances, over 1000 times the wavelength, without diverging, and hence are called non-diffracting beams. In previous reports the Bessel beams were formed by an incident light source, typically with plane-wave illumination on a circular aperture. It was not known if Bessel beams could form from fluorescent light sources. We demonstrate transformation of the emission from fluorescent polystyrene spheres (FPS) into non-diverging beams which propagate up to 130 mm (13 cm) along the optical axis with a constant diameter. This is accomplished using a planar metal film, with no nanoscale features in the X-Y plane, using surface plasmon-coupled emission. Using samples which contain many FPS in the field-of-view, we demonstrate that an independent Bessel beam can be generated from any location on the metal film. The extremely long non-diffracted propagation distances, and self-healing properties of Bessel beams, offer new opportunities in fluorescence sensing and imaging.

PUBLIC INTEGRITY AND THE DIVERGENCE FROM IT

Directory of Open Access Journals (Sweden)

Simona‐Roxana ULMAN

2013-12-01

Full Text Available Public Integrity is one of the public sector’s essential objectives to attain. In contradiction, as a divergence from it, corruption is one of the persistent problems of the societies over years and it affects the credibility of public institutions and its ambassadors in front of the citizens and of the other related countries. All nations complain of corruption and, as it is observed in the Corruption Perception Index 2012, no country has a maximum score which shows that a country is totally clean. In this context, the study of the most important elements of the public integrity concept, the identification of what causes the divergence from it and the solutions detection become a relevant option for economic literature. In this context, the main objective of this paper is to emphasize the public integrity concept and its main aspects and to make a comparison between countries to achieve a large perspective of the world’s public integrity juncture.

Interplay of infrared divergences and gauge-dependence of the effective potential

International Nuclear Information System (INIS)

Espinosa, J.R.; Garny, M.; Konstandin, T.

2016-07-01

The perturbative effective potential suffers infrared (IR) divergences in gauges with massless Goldstones in their minima (like Landau or Fermi gauges) but the problem can be fixed by a suitable resummation of the Goldstone propagators. When the potential minimum is generated radiatively, gauge-independence of the potential at the minimum also requires resummation and we demonstrate that the resummation that solves the IR problem also cures the gauge-dependence issue, showing this explicitly in the Abelian Higgs model in Fermi gauge. In the process we find an IR divergence (in the location of the minimum) specific to Fermi gauge and not appreciated in recent literature. We show that physical observables can still be computed in this gauge and we further show how to get rid of this divergence by a field redefinition. All these results generalize to the Standard Model case.

Interplay of Infrared Divergences and Gauge-Dependence of the Effective Potential

CERN Document Server

Espinosa, J.R.; Konstandin, T.

2016-01-01

The perturbative effective potential suffers infrared (IR) divergences in gauges with massless Goldstones in their minima (like Landau or Fermi gauges) but the problem can be fixed by a suitable resummation of the Goldstone propagators. When the potential minimum is generated radiatively, gauge-independence of the potential at the minimum also requires resummation and we demonstrate that the resummation that solves the IR problem also cures the gauge-dependence issue, showing this explicitly in the Abelian Higgs model in Fermi gauge. In the process we find an IR divergence (in the location of the minimum) specific to Fermi gauge and not appreciated in recent literature. We show that physical observables can still be computed in this gauge and we further show how to get rid of this divergence by a field redefinition. All these results generalize to the Standard Model case.

Transmission dynamics of malaria in Nigeria. | Okwa | Annals of ...

African Journals Online (AJOL)

Background: Two of the problems of malaria parasite vector control in Nigeria are the diversity of Anopheline vectors and large size of the country. Anopheline distribution and transmission dynamics of malaria were therefore compared between four ecotypes in Nigeria during the rainy season. Methods: Polymerase chain ...

Niche divergence facilitated by fine-scale ecological partitioning in a recent cichlid fish adaptive radiation.

Science.gov (United States)

Ford, Antonia G P; Rüber, Lukas; Newton, Jason; Dasmahapatra, Kanchon K; Balarin, John D; Bruun, Kristoffer; Day, Julia J

2016-12-01

Ecomorphological differentiation is a key feature of adaptive radiations, with a general trend for specialization and niche expansion following divergence. Ecological opportunity afforded by invasion of a new habitat is thought to act as an ecological release, facilitating divergence, and speciation. Here, we investigate trophic adaptive morphology and ecology of an endemic clade of oreochromine cichlid fishes (Alcolapia) that radiated along a herbivorous trophic axis following colonization of an isolated lacustrine environment, and demonstrate phenotype-environment correlation. Ecological and morphological divergence of the Alcolapia species flock are examined in a phylogenomic context, to infer ecological niche occupation within the radiation. Species divergence is observed in both ecology and morphology, supporting the importance of ecological speciation within the radiation. Comparison with an outgroup taxon reveals large-scale ecomorphological divergence but shallow genomic differentiation within the Alcolapia adaptive radiation. Ancestral morphological reconstruction suggests lake colonization by a generalist oreochromine phenotype that diverged in Lake Natron to varied herbivorous morphologies akin to specialist herbivores in Lakes Tanganyika and Malawi. © 2016 The Author(s). Evolution published by Wiley Periodicals, Inc. on behalf of The Society for the Study of Evolution.

Alongshore wind stress and heat flux divergence off Visakhapatnam, east coast of India

Digital Repository Service at National Institute of Oceanography (India)

Sadhuram, Y.; Rao, B.P.; Rao, D.P.

Annual variation of heat flux divergence (Qv) was computed for the coastal waters of Visakhapatnam. The mean values of net heat exchange (Qn) and heat flux divergence (Qv) were found to be 114 and 115 W.m/2 respectively on annual scale. The net heat...

Divergent biparietal diameter growth rates in twin pregnancies.

Science.gov (United States)

Houlton, M C

1977-05-01

Twenty-eight twin pregnancies were monitored by serial ultrasonic cephalometry from 30 or 31 weeks' gestation. The rates of growth of the individual twins as determined by biparietal diameters were similar in 11 cases (39%) and divergent in 17 (61%). When the rates of growth were divergent, the lesser rate was always below the mean for singleton pregnancies, and the incidence of small-for-gestational-age babies was 18 of 34 (53%). It was apparent that the greater the difference in biparietal diameters within the 2 weeks preceding delivery, the higher the risk of a small-for-gestation-age baby being delivered. No comment could be made on the growth rate prior to 28 weeks except that at diagnosis there was little or no difference in biparietal diameters.

Divergence-free MHD Simulations with the HERACLES Code

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Vides J.

2013-12-01

Full Text Available Numerical simulations of the magnetohydrodynamics (MHD equations have played a significant role in plasma research over the years. The need of obtaining physical and stable solutions to these equations has led to the development of several schemes, all requiring to satisfy and preserve the divergence constraint of the magnetic field numerically. In this paper, we aim to show the importance of maintaining this constraint numerically. We investigate in particular the hyperbolic divergence cleaning technique applied to the ideal MHD equations on a collocated grid and compare it to the constrained transport technique that uses a staggered grid to maintain the property. The methods are implemented in the software HERACLES and several numerical tests are presented, where the robustness and accuracy of the different schemes can be directly compared.

Anomalous ultraviolet divergences and renormalizability of the light-cone gauge

International Nuclear Information System (INIS)

Lee, H.C.; Milgram, M.S.

1985-01-01

The one-loop renormalizability of both the two-component (LC2) and four-component (LC4) formulations of the light-cone gauge is demonstrated by construction of the complete one-loop counter Lagrangians. The Mandelstam-Leibbrandt prescription is used to regularize the singular 1/p + factor. In LC4, the one-loop self-energy and three-vertex both have anomalous, unrenormalizable ultraviolet divergences, but the counterterms associated with these divergences cancel exactly, rendering the total counter Lagrangians for the two formulations identical, at least to O(g 3 )

Anomalous ultraviolet divergences and renormalizability of the light-cone gauge

Science.gov (United States)

Lee, H. C.; Milgram, M. S.

1985-11-01

The one-loop renormalizability of both the two-component (LC2) and four-component (LC4) formulations of the light-cone gauge is demonstrated by construction of the complete one-loop counter Lagrangians. The Mandelstam-Leibbrandt prescription is used to regularize the singular 1/p+ factor. In LC4, the one-loop self-energy and three-vertex both have anomalous, unrenormalizable ultraviolet divergences, but the counterterms associated with these divergences cancel exactly, rendering the total counter Lagrangians for the two formulations identical, at least to O(g3).

Acidic ribosomal proteins and histone H3 from Leishmania present a high rate of divergence

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Ysabel Montoya

2000-08-01

Full Text Available Another additional peculiarity in Leishmania will be discussed about of the amino acid divergence rate of three structural proteins: acidic ribosomal P1 and P2b proteins, and histone H3 by using multiple sequence alignment and dendrograms. These structural proteins present a high rate of divergence regarding to their homologous protein in Trypanosoma cruzi. At this regard, L. (V. peruviana P1 and T. cruzi P1 showed 57.4% of divergence rate. Likewise, L. (V. braziliensis histone H3 and acidic ribosomal P2 protein exhibited 31.8% and 41.7% respectively of rate of divergence in comparison with their homologous in T. cruzi.

Computation of diverging sums based on a finite number of terms

Science.gov (United States)

Lv, Q. Z.; Norris, S.; Pelphrey, R.; Su, Q.; Grobe, R.

2017-10-01

We propose a numerical method that permits us to compute the sum of a diverging series from only the first N terms by generalizing the traditional Borel technique. The method is rather robust and can be used to recover the ground state energy from the diverging perturbation theory for quantum field theoretical systems that are spatially constrained. Surprisingly, even the corresponding eigenvectors can be generated despite the intrinsic non-perturbative nature of bound state problems.

Reduction of angular divergence of laser-driven ion beams during their acceleration and transport

Science.gov (United States)

Zakova, M.; Pšikal, Jan; Margarone, Daniele; Maggiore, Mario; Korn, G.

2015-05-01

Laser plasma physics is a field of big interest because of its implications in basic science, fast ignition, medicine (i.e. hadrontherapy), astrophysics, material science, particle acceleration etc. 100-MeV class protons accelerated from the interaction of a short laser pulse with a thin target have been demonstrated. With continuing development of laser technology, greater and greater energies are expected, therefore projects focusing on various applications are being formed, e.g. ELIMAIA (ELI Multidisciplinary Applications of laser-Ion Acceleration). One of the main characteristic and crucial disadvantage of ion beams accelerated by ultra-short intense laser pulses is their large divergence, not suitable for the most of applications. In this paper two ways how to decrease beam divergence are proposed. Firstly, impact of different design of targets on beam divergence is studied by using 2D Particlein-cell simulations (PIC). Namely, various types of targets include at foils, curved foil and foils with diverse microstructures. Obtained results show that well-designed microstructures, i.e. a hole in the center of the target, can produce proton beam with the lowest divergence. Moreover, the particle beam accelerated from a curved foil has lower divergence compared to the beam from a flat foil. Secondly, another proposed method for the divergence reduction is using of a magnetic solenoid. The trajectories of the laser accelerated particles passing through the solenoid are modeled in a simple Matlab program. Results from PIC simulations are used as input in the program. The divergence is controlled by optimizing the magnetic field inside the solenoid and installing an aperture in front of the device.

The impact of divergence time on the nature of population structure: an example from Iceland.

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Alkes L Price

2009-06-01

Full Text Available The Icelandic population has been sampled in many disease association studies, providing a strong motivation to understand the structure of this population and its ramifications for disease gene mapping. Previous work using 40 microsatellites showed that the Icelandic population is relatively homogeneous, but exhibits subtle population structure that can bias disease association statistics. Here, we show that regional geographic ancestries of individuals from Iceland can be distinguished using 292,289 autosomal single-nucleotide polymorphisms (SNPs. We further show that subpopulation differences are due to genetic drift since the settlement of Iceland 1100 years ago, and not to varying contributions from different ancestral populations. A consequence of the recent origin of Icelandic population structure is that allele frequency differences follow a null distribution devoid of outliers, so that the risk of false positive associations due to stratification is minimal. Our results highlight an important distinction between population differences attributable to recent drift and those arising from more ancient divergence, which has implications both for association studies and for efforts to detect natural selection using population differentiation.

Bilingualism and Creativity: Benefits in Convergent Thinking Come with Losses in Divergent Thinking

Science.gov (United States)

Hommel, Bernhard; Colzato, Lorenza S.; Fischer, Rico; Christoffels, Ingrid K.

2011-01-01

Bilingualism is commonly assumed to improve creativity but the mechanisms underlying creative acts, and the way these mechanisms are affected by bilingualism, are not very well understood. We hypothesize that learning to master multiple languages drives individuals toward a relatively focused cognitive-control state that exerts strong top-down impact on information processing and creates strong local competition for selection between cognitive codes. Considering the control requirements posed by creativity tasks tapping into convergent and divergent thinking, this predicts that high-proficient bilinguals should outperform low-proficient bilinguals in convergent thinking, while low-proficient bilinguals might be better in divergent thinking. Comparing low- and high-proficient bilinguals on convergent-thinking and divergent-thinking tasks indeed showed a high-proficient bilingual advantage for convergent thinking but a low-proficient bilingual advantage for fluency in divergent thinking. These findings suggest that bilingualism should not be related to “creativity” as a unitary concept but, rather, to the specific processes and mechanisms that underlie creativity. PMID:22084634

Bilingualism and creativity: Benefits in convergent thinking come with losses in divergent thinking

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Bernhard eHommel

2011-11-01

Full Text Available Bilingualism is commonly assumed to improve creativity but the mechanisms underlying creative acts, and the way these mechanisms are affected by bilingualism, are not very well understood. We hypothesize that learning to master multiple languages drives individuals towards a strongly focused cognitive-control state that exerts strong top-down impact on information processing and creates strong local competition for selection between cognitive codes. Considering the control requirements posed by creativity tasks tapping into convergent and divergent thinking, this predicts that high-proficient bilinguals should outperform low-proficient bilinguals in convergent thinking, while low-proficient bilinguals might be better in divergent thinking. Comparing low- and high-proficient bilinguals on convergent-thinking and divergent-thinking tasks indeed showed a high-proficient bilingual advantage for convergent thinking but a low-proficient bilingual advantage for fluency in divergent thinking. These findings suggest that bilingualism should not be related to creativity as a unitary concept but, rather, to the specific processes and mechanisms that underlie creativity.

Divergência genética entre cultivares de gérbera utilizando marcadores RAPD Genetic divergence among cultivars of gerbera using RAPD markers

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Rodrigo Kelson Silva Rezende

2009-11-01

Full Text Available No processo de produção comercial de mudas de gérbera, a cor da flor é uma das principais características morfológicas de interesse agronômico, sendo uma característica importante em programas de melhoramento genético. A utilização de marcadores moleculares pode servir para direcionar cruzamentos, confirmar novos híbridos ou genótipos mutantes e identificar novos genótipos para fins comerciais. Nesse contexto, o objetivo deste trabalho foi analisar a divergência genética entre seis cultivares de Gerbera jamesonii ('Jaguar Yellow', 'Jaguar Cream', 'Jaguar Lemon', 'Jaguar Salmon Pastel', 'Jaguar Red', 'Jaguar Deep Rose'. A análise de divergência genética entre as cultivares de gérbera foi realizada utilizando-se 21 primers, os quais amplificaram 37 fragmentos polimórficos de DNA, que foram usados para estimar o coeficiente de Jaccard, o qual apresentou uma média de 0,38, variando de 0,28 a 0,56. A estrutura genética entre as cultivares foi estimada pelo UPGMA, revelando dois grupos distintos, a 38% de similaridade genética. A maior similaridade genética encontrada (56% foi entre as cultivares 'Jaguar Yellow' e 'Jaguar Lemon'. Os resultados demonstram que a técnica RAPD oferece uma maneira rápida, relativamente barata e útil para a caracterização da divergência genética entre as diferentes cultivares de Gerbera jamesonii com relação à cor da flor.During the commercial production of gerbera seedlings, flower color is one of the main morphological aspects that have an agronomic interest and becoming an important feature in genetic breeding programs. The use of molecular markers may serve to direct crossings, new hybrids and mutants, besides confirm and identify new genotypes for commercial purposes. In that context, this work aimed to analyze the genetic divergence among six cultivars of Gerbera jamesonii ('Jaguar Yellow', 'Jaguar Cream', 'Jaguar Lemon', 'Jaguar Salmon Pastel', 'Jaguar Red', 'Jaguar Deep Rose'. The

A new isolation with migration model along complete genomes infers very different divergence processes among closely related great ape species.

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Thomas Mailund

Full Text Available We present a hidden Markov model (HMM for inferring gradual isolation between two populations during speciation, modelled as a time interval with restricted gene flow. The HMM describes the history of adjacent nucleotides in two genomic sequences, such that the nucleotides can be separated by recombination, can migrate between populations, or can coalesce at variable time points, all dependent on the parameters of the model, which are the effective population sizes, splitting times, recombination rate, and migration rate. We show by extensive simulations that the HMM can accurately infer all parameters except the recombination rate, which is biased downwards. Inference is robust to variation in the mutation rate and the recombination rate over the sequence and also robust to unknown phase of genomes unless they are very closely related. We provide a test for whether divergence is gradual or instantaneous, and we apply the model to three key divergence processes in great apes: (a the bonobo and common chimpanzee, (b the eastern and western gorilla, and (c the Sumatran and Bornean orang-utan. We find that the bonobo and chimpanzee appear to have undergone a clear split, whereas the divergence processes of the gorilla and orang-utan species occurred over several hundred thousands years with gene flow stopping quite recently. We also apply the model to the Homo/Pan speciation event and find that the most likely scenario involves an extended period of gene flow during speciation.

Natural and sexual selection giveth and taketh away reproductive barriers: models of population divergence in guppies.

Science.gov (United States)

Labonne, Jacques; Hendry, Andrew P

2010-07-01

The standard predictions of ecological speciation might be nuanced by the interaction between natural and sexual selection. We investigated this hypothesis with an individual-based model tailored to the biology of guppies (Poecilia reticulata). We specifically modeled the situation where a high-predation population below a waterfall colonizes a low-predation population above a waterfall. Focusing on the evolution of male color, we confirm that divergent selection causes the appreciable evolution of male color within 20 generations. The rate and magnitude of this divergence were reduced when dispersal rates were high and when female choice did not differ between environments. Adaptive divergence was always coupled to the evolution of two reproductive barriers: viability selection against immigrants and hybrids. Different types of sexual selection, however, led to contrasting results for another potential reproductive barrier: mating success of immigrants. In some cases, the effects of natural and sexual selection offset each other, leading to no overall reproductive isolation despite strong adaptive divergence. Sexual selection acting through female choice can thus strongly modify the effects of divergent natural selection and thereby alter the standard predictions of ecological speciation. We also found that under no circumstances did divergent selection cause appreciable divergence in neutral genetic markers.

Divergência genética entre acessos de feijão-de-vagem de hábito de crescimento indeterminado Genetic divergence among climbing snap bean accessions

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Flávia B. Abreu

2004-09-01

Full Text Available Devido à importância da cultura do feijão-de-vagem no contexto da agricultura do RJ, a busca por cultivares com maior produção e melhor qualidade é de elevada importância. A determinação da divergência genética, com o uso da análise multivariada, em que diversos caracteres podem ser dimensionados simultaneamente, apresenta-se bastante vantajosa, podendo-se identificar fontes de variabilidade genética, avaliar a importância dos caracteres para a divergência genética, além de permitir aos melhoristas identificar combinações genéticas com maiores chances de sucesso, antes de se realizarem os cruzamentos. Através de técnicas de análise multivariada, verificou-se que acessos de feijão-de-vagem de hábito de crescimento indeterminado, do banco de germoplasma da UENF, apresentaram variabilidade em relação às características avaliadas. O método de otimização de Tocher permitiu a formação de dois grupos, todavia o subagrupamento pelo mesmo método confirmou a presença de variabilidade entre os acessos do grupo 1, pela formação de seis subgrupos. Por este método, verificou-se que não houve relação entre a diversidade genética e a origem geográfica dos acessos. A divergência genética observada entre os acessos de feijão-de-vagem foi quantificada pelas três primeiras variáveis canônicas, que explicaram cerca de 79% da variação total disponível. O descarte das variáveis de menor importância relativa permitiu identificar as características que realmente contribuíram para a determinação da divergência genética: peso de cem sementes, dias para florescimento, diâmetro de vagem, comprimento de vagem, número total de vagens e número médio de vagens. Os acessos UENF-1429, UENF-1432, UENF-1442, UENF-1445 e UENF-1448 apresentaram bom desempenho para as características avaliadas e boa divergência genética entre si, sendo indicadas para o uso do programa de melhoramento genético do feij

Genetic divergence among hybrids of 'Cravo' mandarin with 'Pêra' sweet orange Divergência genética entre híbridos de tangerina 'Cravo' com laranja 'Pêra'

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Roberto Pedroso de Oliveira

2003-02-01

Full Text Available Molecular markers have been used as tools in breading programs of sexual hybridation, allowing the genetic characterization of a large number of genotypes. The RADP markers are the most used since the employed techniques are simple and of low cost. To evaluate the genetic divergence among F1 hybrids of 'Cravo' mandarin (Citrus reticulata Blanco and 'Pêra' sweet orange (C. sinensis (L. Osbeck, this study analyses the variability and similarity of the hybrids among themselves and with their parents. Random Amplified Polimorfic DNA marker analysis, with 102 primers, were applied to a population composed of 94 hybrids and their parents. Multivariate genetic divergence analysis of the principal components and Tocher grouping were carried out only considering the polymorphic fragments. Genetic distances were calculated by the arithmetic complement of the Jaccard index. Bidimensional dispersion graphs among hybrid and parent distances and of the divergence analysis by principal components were constructed. High genetic similarity among Cravo and Pêra varieties and their hybrids was verified, showing a casual distribution from the hybrids in relation to the parents, but in intermediary positions. The principal component analysis showed little applicability in the study of hybrid genetic divergence. The hybrids and parents were classified in groups based on the genetic similarity, using the Tocher optimization method.Os marcadores moleculares têm sido utilizados como ferramentas em programas de melhoramento por hibridação sexual, permitindo a caracterização genética de grande número de genótipos. Os marcadores moleculares RAPD são os mais utilizados pois as técnicas empregadas são simples e de baixo custo. Avaliou-se a divergência genética entre híbridos F1 de tangerina 'Cravo' (Citrus reticulata Blanco com laranja 'Pêra' (C. sinensis (L. Osbeck e estudou-se a variabilidade e a similaridade desses materiais entre si e em relação aos

Bounding the bias of contrastive divergence learning

DEFF Research Database (Denmark)

Fischer, Anja; Igel, Christian

2011-01-01

Optimization based on k-step contrastive divergence (CD) has become a common way to train restricted Boltzmann machines (RBMs). The k-step CD is a biased estimator of the log-likelihood gradient relying on Gibbs sampling. We derive a new upper bound for this bias. Its magnitude depends on k...

Mutations in the voltage-gated sodium channel gene of anophelines and their association with resistance to pyrethroids - a review.

Science.gov (United States)

Silva, Ana Paula B; Santos, Joselita Maria M; Martins, Ademir J

2014-10-07

Constant and extensive use of chemical insecticides has created a selection pressure and favored resistance development in many insect species worldwide. One of the most important pyrethroid resistance mechanisms is classified as target site insensitivity, due to conformational changes in the target site that impair a proper binding of the insecticide molecule. The voltage-gated sodium channel (NaV) is the target of pyrethroids and DDT insecticides, used to control insects of medical, agricultural and veterinary importance, such as anophelines. It has been reported that the presence of a few non-silent point mutations in the NaV gene are associated with pyrethroid resistance, termed as 'kdr' (knockdown resistance) for preventing the knockdown effect of these insecticides. The presence of these mutations, as well as their effects, has been thoroughly studied in Anopheles mosquitoes. So far, kdr mutations have already been detected in at least 13 species (Anopheles gambiae, Anopheles arabiensis, Anopheles sinensis, Anopheles stephensi, Anopheles subpictus, Anopheles sacharovi, Anopheles culicifacies, Anopheles sundaicus, Anopheles aconitus, Anopheles vagus, Anopheles paraliae, Anopheles peditaeniatus and Anopheles albimanus) from populations of African, Asian and, more recently, American continents. Seven mutational variants (L1014F, L1014S, L1014C, L1014W, N1013S, N1575Y and V1010L) were described, with the highest prevalence of L1014F, which occurs at the 1014 site in NaV IIS6 domain. The increase of frequency and distribution of kdr mutations clearly shows the importance of this mechanism in the process of pyrethroid resistance. In this sense, several species-specific and highly sensitive methods have been designed in order to genotype individual mosquitoes for kdr in large scale, which may serve as important tolls for monitoring the dynamics of pyrethroid resistance in natural populations. We also briefly discuss investigations concerning the course of Plasmodium

Statistics of surface divergence and their relation to air-water gas transfer velocity

Science.gov (United States)

Asher, William E.; Liang, Hanzhuang; Zappa, Christopher J.; Loewen, Mark R.; Mukto, Moniz A.; Litchendorf, Trina M.; Jessup, Andrew T.

2012-05-01

Air-sea gas fluxes are generally defined in terms of the air/water concentration difference of the gas and the gas transfer velocity,kL. Because it is difficult to measure kLin the ocean, it is often parameterized using more easily measured physical properties. Surface divergence theory suggests that infrared (IR) images of the water surface, which contain information concerning the movement of water very near the air-water interface, might be used to estimatekL. Therefore, a series of experiments testing whether IR imagery could provide a convenient means for estimating the surface divergence applicable to air-sea exchange were conducted in a synthetic jet array tank embedded in a wind tunnel. Gas transfer velocities were measured as a function of wind stress and mechanically generated turbulence; laser-induced fluorescence was used to measure the concentration of carbon dioxide in the top 300 μm of the water surface; IR imagery was used to measure the spatial and temporal distribution of the aqueous skin temperature; and particle image velocimetry was used to measure turbulence at a depth of 1 cm below the air-water interface. It is shown that an estimate of the surface divergence for both wind-shear driven turbulence and mechanically generated turbulence can be derived from the surface skin temperature. The estimates derived from the IR images are compared to velocity field divergences measured by the PIV and to independent estimates of the divergence made using the laser-induced fluorescence data. Divergence is shown to scale withkLvalues measured using gaseous tracers as predicted by conceptual models for both wind-driven and mechanically generated turbulence.

DNA barcoding of recently diverged species: relative performance of matching methods.

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Robin van Velzen

Full Text Available Recently diverged species are challenging for identification, yet they are frequently of special interest scientifically as well as from a regulatory perspective. DNA barcoding has proven instrumental in species identification, especially in insects and vertebrates, but for the identification of recently diverged species it has been reported to be problematic in some cases. Problems are mostly due to incomplete lineage sorting or simply lack of a 'barcode gap' and probably related to large effective population size and/or low mutation rate. Our objective was to compare six methods in their ability to correctly identify recently diverged species with DNA barcodes: neighbor joining and parsimony (both tree-based, nearest neighbor and BLAST (similarity-based, and the diagnostic methods DNA-BAR, and BLOG. We analyzed simulated data assuming three different effective population sizes as well as three selected empirical data sets from published studies. Results show, as expected, that success rates are significantly lower for recently diverged species (∼75% than for older species (∼97% (P<0.00001. Similarity-based and diagnostic methods significantly outperform tree-based methods, when applied to simulated DNA barcode data (P<0.00001. The diagnostic method BLOG had highest correct query identification rate based on simulated (86.2% as well as empirical data (93.1%, indicating that it is a consistently better method overall. Another advantage of BLOG is that it offers species-level information that can be used outside the realm of DNA barcoding, for instance in species description or molecular detection assays. Even though we can confirm that identification success based on DNA barcoding is generally high in our data, recently diverged species remain difficult to identify. Nevertheless, our results contribute to improved solutions for their accurate identification.

Niche evolution and adaptive radiation: Testing the order of trait divergence

Science.gov (United States)

Ackerly, D.D.; Schwilk, D.W.; Webb, C.O.

2006-01-01

In the course of an adaptive radiation, the evolution of niche parameters is of particular interest for understanding modes of speciation and the consequences for coexistence of related species within communities. We pose a general question: In the course of an evolutionary radiation, do traits related to within-community niche differences (?? niche) evolve before or after differentiation of macrohabitat affinity or climatic tolerances (?? niche)? Here we introduce a new test to address this question, based on a modification of the method of independent contrasts. The divergence order test (DOT) is based on the average age of the nodes on a tree, weighted by the absolute magnitude of the contrast at each node for a particular trait. The comparison of these weighted averages reveals whether large divergences for one trait have occurred earlier or later in the course of diversification, relative to a second trait; significance is determined by bootstrapping from maximum-likelihood ancestral state reconstructions. The method is applied to the evolution of Ceanothus, a woody plant group in California, in which co-occurring species exhibit significant differences in a key leaf trait (specific leaf area) associated with contrasting physiological and life history strategies. Co-occurring species differ more for this trait than expected under a null model of community assembly. This ?? niche difference evolved early in the divergence of two major subclades within Ceanothus, whereas climatic distributions (?? niche traits) diversified later within each of the subclades. However, rapid evolution of climate parameters makes inferences of early divergence events highly uncertain, and differentiation of the ?? niche might have taken place throughout the evolution of the group, without leaving a clear phylogenetic signal. Similar patterns observed in several plant and animal groups suggest that early divergence of ?? niche traits might be a common feature of niche evolution in

The impact of selection, gene flow and demographic history on heterogeneous genomic divergence: three-spine sticklebacks in divergent environments.

Science.gov (United States)

Ferchaud, Anne-Laure; Hansen, Michael M

2016-01-01

Heterogeneous genomic divergence between populations may reflect selection, but should also be seen in conjunction with gene flow and drift, particularly population bottlenecks. Marine and freshwater three-spine stickleback (Gasterosteus aculeatus) populations often exhibit different lateral armour plate morphs. Moreover, strikingly parallel genomic footprints across different marine-freshwater population pairs are interpreted as parallel evolution and gene reuse. Nevertheless, in some geographic regions like the North Sea and Baltic Sea, different patterns are observed. Freshwater populations in coastal regions are often dominated by marine morphs, suggesting that gene flow overwhelms selection, and genomic parallelism may also be less pronounced. We used RAD sequencing for analysing 28 888 SNPs in two marine and seven freshwater populations in Denmark, Europe. Freshwater populations represented a variety of environments: river populations accessible to gene flow from marine sticklebacks and large and small isolated lakes with and without fish predators. Sticklebacks in an accessible river environment showed minimal morphological and genomewide divergence from marine populations, supporting the hypothesis of gene flow overriding selection. Allele frequency spectra suggested bottlenecks in all freshwater populations, and particularly two small lake populations. However, genomic footprints ascribed to selection could nevertheless be identified. No genomic regions were consistent freshwater-marine outliers, and parallelism was much lower than in other comparable studies. Two genomic regions previously described to be under divergent selection in freshwater and marine populations were outliers between different freshwater populations. We ascribe these patterns to stronger environmental heterogeneity among freshwater populations in our study as compared to most other studies, although the demographic history involving bottlenecks should also be considered in the

Divergence of iron metabolism in wild Malaysian yeast.

Science.gov (United States)

Lee, Hana N; Mostovoy, Yulia; Hsu, Tiffany Y; Chang, Amanda H; Brem, Rachel B

2013-12-09

Comparative genomic studies have reported widespread variation in levels of gene expression within and between species. Using these data to infer organism-level trait divergence has proven to be a key challenge in the field. We have used a wild Malaysian population of S. cerevisiae as a test bed in the search to predict and validate trait differences based on observations of regulatory variation. Malaysian yeast, when cultured in standard medium, activated regulatory programs that protect cells from the toxic effects of high iron. Malaysian yeast also showed a hyperactive regulatory response during culture in the presence of excess iron and had a unique growth defect in conditions of high iron. Molecular validation experiments pinpointed the iron metabolism factors AFT1, CCC1, and YAP5 as contributors to these molecular and cellular phenotypes; in genome-scale sequence analyses, a suite of iron toxicity response genes showed evidence for rapid protein evolution in Malaysian yeast. Our findings support a model in which iron metabolism has diverged in Malaysian yeast as a consequence of a change in selective pressure, with Malaysian alleles shifting the dynamic range of iron response to low-iron concentrations and weakening resistance to extreme iron toxicity. By dissecting the iron scarcity specialist behavior of Malaysian yeast, our work highlights the power of expression divergence as a signpost for biologically and evolutionarily relevant variation at the organismal level. Interpreting the phenotypic relevance of gene expression variation is one of the primary challenges of modern genomics.

A vadose zone water fluxmeter with divergence control

Science.gov (United States)

Gee, G.W.; Ward, A.L.; Caldwell, T.G.; Ritter, J.C.

2002-01-01

Unsaturated water flux densities are needed to quantify water and contaminant transfer within the vadose zone. However, water flux densities are seldom measured directly and often are predicted with uncertainties of an order or magnitude or more. A water fluxmeter was designed, constructed, and tested to directly measure drainage fluxes in field soils. The fluxmeter was designed to minimize divergence. It concentrates flow into a narrow sensing region filled with a fiberglass wick. The wick applies suction, proportional to its length, and passively drains the meter. The meter can be installed in an augured borehole at almost any depth below the root zone. Water flux through the meter is measured with a self‐calibrating tipping bucket, with a sensitivity of ∼4 mL tip−1. For our meter this is equivalent to detection limit of ∼0.1 mm. Passive‐wick devices previously have not properly corrected for flow divergence. Laboratory measurements supported predictions of a two‐dimensional (2‐D) numerical model, which showed that control of the collector height H and knowledge of soil hydraulic properties are required for improving divergence control, particularly at fluxes below 1000 mm yr−1. The water fluxmeter is simple in concept, is inexpensive, and has the capability of providing continuous and reliable monitoring of unsaturated water fluxes ranging from less than 1 mm yr−1 to more than 1000 mm yr−1.

Stora's fine notion of divergent amplitudes

International Nuclear Information System (INIS)

Várilly, Joseph C.; Gracia-Bondía, José M.

2016-01-01

Stora and coworkers refined the notion of divergent quantum amplitude, somewhat upsetting the standard power-counting recipe. This unexpectedly clears the way to new prototypes for free and interacting field theories of bosons of any mass and spin.

An automated optimization tool for high-dose-rate (HDR) prostate brachytherapy with divergent needle pattern

Science.gov (United States)

Borot de Battisti, M.; Maenhout, M.; de Senneville, B. Denis; Hautvast, G.; Binnekamp, D.; Lagendijk, J. J. W.; van Vulpen, M.; Moerland, M. A.

2015-10-01

Focal high-dose-rate (HDR) for prostate cancer has gained increasing interest as an alternative to whole gland therapy as it may contribute to the reduction of treatment related toxicity. For focal treatment, optimal needle guidance and placement is warranted. This can be achieved under MR guidance. However, MR-guided needle placement is currently not possible due to space restrictions in the closed MR bore. To overcome this problem, a MR-compatible, single-divergent needle-implant robotic device is under development at the University Medical Centre, Utrecht: placed between the legs of the patient inside the MR bore, this robot will tap the needle in a divergent pattern from a single rotation point into the tissue. This rotation point is just beneath the perineal skin to have access to the focal prostate tumor lesion. Currently, there is no treatment planning system commercially available which allows optimization of the dose distribution with such needle arrangement. The aim of this work is to develop an automatic inverse dose planning optimization tool for focal HDR prostate brachytherapy with needle insertions in a divergent configuration. A complete optimizer workflow is proposed which includes the determination of (1) the position of the center of rotation, (2) the needle angulations and (3) the dwell times. Unlike most currently used optimizers, no prior selection or adjustment of input parameters such as minimum or maximum dose or weight coefficients for treatment region and organs at risk is required. To test this optimizer, a planning study was performed on ten patients (treatment volumes ranged from 8.5 cm3to 23.3 cm3) by using 2-14 needle insertions. The total computation time of the optimizer workflow was below 20 min and a clinically acceptable plan was reached on average using only four needle insertions.

Convergence accommodation to convergence CA/C ratio: convergence versus divergence.

Science.gov (United States)

Simmons, Joshua M; Firth, Alison Y

2014-09-01

To determine whether the convergence accommodation to convergence (CA/C) ratio during divergence with base-in (BI) prisms is of a similar or different magnitude to that measured during convergence with base-out (BO) prisms. Eighteen participants with normal binocular single vision were recruited. The participants viewed a pseudo-Gaussian target, which consisted of a light emitting diode (LED) behind a diffusing screen at 40 cm. After 5 minutes of dark adaptation, the refractive status of the eye was measured without any prism using a Shin-Nippon SRW-5000 autorefractor. The participant held the selected prism (5Δ or 10Δ BO or BI, counterbalanced) in front of their right eye and obtained a single, fused image of the target while refractive measures were taken with each. A 30-second rest period was given between measurements. The mean age of the participants was 20.6±3.22 years. The mean CA/C ratios for the 5Δ BO, 10Δ BO, 5Δ BI, and 10Δ BI were 0.108 (±0.074) D/Δ, 0.110 (±0.056) D/Δ, 0.100 (±0.090) D/Δ, and 0.089 (±0.055) D/Δ, respectively. A 2-factor repeated measures ANOVA found that the CA/C ratio did not significantly change with differing levels of prism-induced convergence and divergence (p=0.649). Change in accommodation induced by manipulating vergence is similar whether convergence or divergence are induced. The CA/C ratio did not show any change with differing levels of prism-induced convergence and divergence.

New hybrid non-linear transformations of divergent perturbation series for quadratic Zeeman effects

International Nuclear Information System (INIS)

Belkic, D.

1989-01-01

The problem of hydrogen atoms in an external uniform magnetic field (quadratic Zeeman effect) is studied by means of perturbation theory. The power series for the ground-state energy in terms of magnetic-field strength B is divergent. Nevertheless, it is possible to induce convergence of this divergent series by applying various non-linear transformations. These transformations of originally divergent perturbation series yield new sequences, which then converge. The induced convergence is, however, quite slow. A new hybrid Shanks-Levin non-linear transform is devised here for accelerating these slowly converging series and sequences. Significant improvement in the convergence rate is obtained. Agreement with the exact results is excellent. (author)

Ultraviolet divergences and supersymmetric theories

International Nuclear Information System (INIS)

Sagnotti, A.

1984-09-01

This article is closely related to the one by Ferrara in these same Proceedings. It deals with what is perhaps the most fascinating property of supersymmetric theories, their improved ultraviolet behavior. My aim here is to present a survey of the state of the art as of August, 1984, and a somewhat more detailed discussion of the breakdown of the superspace power-counting beyond N = 2 superfields. A method is also described for simplifying divergence calculations that uses the locality of subtracted Feynman integrals. 74 references

Performance evaluation of block-diagonal preconditioners for the divergence-conforming B-spline discretization of the Stokes system

KAUST Repository

Cô rtes, A.M.A.; Coutinho, A.L.G.A.; Dalcin, L.; Calo, Victor M.

2015-01-01

The recently introduced divergence-conforming B-spline discretizations allow the construction of smooth discrete velocity–pressure pairs for viscous incompressible flows that are at the same time inf-sup stable and pointwise divergence-free. When applied to discretized Stokes equations, these spaces generate a symmetric and indefinite saddle-point linear system. Krylov subspace methods are usually the most efficient procedures to solve such systems. One of such methods, for symmetric systems, is the Minimum Residual Method (MINRES). However, the efficiency and robustness of Krylov subspace methods is closely tied to appropriate preconditioning strategies. For the discrete Stokes system, in particular, block-diagonal strategies provide efficient preconditioners. In this article, we compare the performance of block-diagonal preconditioners for several block choices. We verify how the eigenvalue clustering promoted by the preconditioning strategies affects MINRES convergence. We also compare the number of iterations and wall-clock timings. We conclude that among the building blocks we tested, the strategy with relaxed inner conjugate gradients preconditioned with incomplete Cholesky provided the best results.

Performance evaluation of block-diagonal preconditioners for the divergence-conforming B-spline discretization of the Stokes system

KAUST Repository

Côrtes, A.M.A.

2015-02-20

The recently introduced divergence-conforming B-spline discretizations allow the construction of smooth discrete velocity–pressure pairs for viscous incompressible flows that are at the same time inf-sup stable and pointwise divergence-free. When applied to discretized Stokes equations, these spaces generate a symmetric and indefinite saddle-point linear system. Krylov subspace methods are usually the most efficient procedures to solve such systems. One of such methods, for symmetric systems, is the Minimum Residual Method (MINRES). However, the efficiency and robustness of Krylov subspace methods is closely tied to appropriate preconditioning strategies. For the discrete Stokes system, in particular, block-diagonal strategies provide efficient preconditioners. In this article, we compare the performance of block-diagonal preconditioners for several block choices. We verify how the eigenvalue clustering promoted by the preconditioning strategies affects MINRES convergence. We also compare the number of iterations and wall-clock timings. We conclude that among the building blocks we tested, the strategy with relaxed inner conjugate gradients preconditioned with incomplete Cholesky provided the best results.

Highly divergent 16S rRNA sequences in ribosomal operons of Scytonema hyalinum (Cyanobacteria.

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Jeffrey R Johansen

Full Text Available A highly divergent 16S rRNA gene was found in one of the five ribosomal operons present in a species complex currently circumscribed as Scytonema hyalinum (Nostocales, Cyanobacteria using clone libraries. If 16S rRNA sequence macroheterogeneity among ribosomal operons due to insertions, deletions or truncation is excluded, the sequence heterogeneity observed in S. hyalinum was the highest observed in any prokaryotic species thus far (7.3-9.0%. The secondary structure of the 16S rRNA molecules encoded by the two divergent operons was nearly identical, indicating possible functionality. The 23S rRNA gene was examined for a few strains in this complex, and it was also found to be highly divergent from the gene in Type 2 operons (8.7%, and likewise had nearly identical secondary structure between the Type 1 and Type 2 operons. Furthermore, the 16S-23S ITS showed marked differences consistent between operons among numerous strains. Both operons have promoter sequences that satisfy consensus requirements for functional prokaryotic transcription initiation. Horizontal gene transfer from another unknown heterocytous cyanobacterium is considered the most likely explanation for the origin of this molecule, but does not explain the ultimate origin of this sequence, which is very divergent from all 16S rRNA sequences found thus far in cyanobacteria. The divergent sequence is highly conserved among numerous strains of S. hyalinum, suggesting adaptive advantage and selective constraint of the divergent sequence.

Ecological divergence and conservatism: spatiotemporal patterns of niche evolution in a genus of livebearing fishes (Poeciliidae: Xiphophorus).

Science.gov (United States)

Culumber, Zachary W; Tobler, Michael

2016-02-19

Ecological factors often have a strong impact on spatiotemporal patterns of biodiversity. The integration of spatial ecology and phylogenetics allows for rigorous tests of whether speciation is associated with niche conservatism (constraints on ecological divergence) or niche divergence. We address this question in a genus of livebearing fishes for which the role of sexual selection in speciation has long been studied, but in which the potential role of ecological divergence during speciation has not been tested. By combining reconstruction of ancestral climate tolerances and disparity indices, we show that the earliest evolutionary split in Xiphophorus was associated with significant divergence for temperature variables. Niche evolution and present day niches were most closely associated with each species' geographic distribution relative to a biogeographic barrier, the Trans-Mexican Volcanic Belt. Tests for similarity of the environmental backgrounds of closely related species suggested that the relative importance of niche conservatism and divergence during speciation varied among the primary clades of Xiphophorus. Closely related species in the two swordtail clades exhibited higher levels of niche overlap than expected given environmental background similarity indicative of niche conservatism. In contrast, almost all species of platyfish had significantly divergent niches compared to environmental backgrounds, which is indicative of niche divergence. The results suggest that the relative importance of niche conservatism and divergence differed among the clades of Xiphophorus and that traits associated with niche evolution may be more evolutionarily labile in the platyfishes. Our results ultimately suggest that the taxonomic scale of tests for conservatism and divergence could greatly influence inferences of their relative importance in the speciation process.

Functional genetic divergence in high CO2 adapted Emiliania huxleyi populations.

Science.gov (United States)

Lohbeck, Kai T; Riebesell, Ulf; Collins, Sinéad; Reusch, Thorsten B H

2013-07-01

Predicting the impacts of environmental change on marine organisms, food webs, and biogeochemical cycles presently relies almost exclusively on short-term physiological studies, while the possibility of adaptive evolution is often ignored. Here, we assess adaptive evolution in the coccolithophore Emiliania huxleyi, a well-established model species in biological oceanography, in response to ocean acidification. We previously demonstrated that this globally important marine phytoplankton species adapts within 500 generations to elevated CO2 . After 750 and 1000 generations, no further fitness increase occurred, and we observed phenotypic convergence between replicate populations. We then exposed adapted populations to two novel environments to investigate whether or not the underlying basis for high CO2 -adaptation involves functional genetic divergence, assuming that different novel mutations become apparent via divergent pleiotropic effects. The novel environment "high light" did not reveal such genetic divergence whereas growth in a low-salinity environment revealed strong pleiotropic effects in high CO2 adapted populations, indicating divergent genetic bases for adaptation to high CO2 . This suggests that pleiotropy plays an important role in adaptation of natural E. huxleyi populations to ocean acidification. Our study highlights the potential mutual benefits for oceanography and evolutionary biology of using ecologically important marine phytoplankton for microbial evolution experiments. © 2012 The Author(s). Evolution © 2012 The Society for the Study of Evolution.

Genome-Wide Divergence in the West-African Malaria Vector Anopheles melas

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Kevin C. Deitz

2016-09-01

Full Text Available Anopheles melas is a member of the recently diverged An. gambiae species complex, a model for speciation studies, and is a locally important malaria vector along the West-African coast where it breeds in brackish water. A recent population genetic study of An. melas revealed species-level genetic differentiation between three population clusters. An. melas West extends from The Gambia to the village of Tiko, Cameroon. The other mainland cluster, An. melas South, extends from the southern Cameroonian village of Ipono to Angola. Bioko Island, Equatorial Guinea An. melas populations are genetically isolated from mainland populations. To examine how genetic differentiation between these An. melas forms is distributed across their genomes, we conducted a genome-wide analysis of genetic differentiation and selection using whole genome sequencing data of pooled individuals (Pool-seq from a representative population of each cluster. The An. melas forms exhibit high levels of genetic differentiation throughout their genomes, including the presence of numerous fixed differences between clusters. Although the level of divergence between the clusters is on a par with that of other species within the An. gambiae complex, patterns of genome-wide divergence and diversity do not provide evidence for the presence of pre- and/or postmating isolating mechanisms in the form of speciation islands. These results are consistent with an allopatric divergence process with little or no introgression.

Increased genetic divergence between two closely related fir species in areas of range overlap

Science.gov (United States)

Wang, Jing; Abbott, Richard J; Ingvarsson, Pär K; Liu, Jianquan

2014-01-01

Because of introgressive hybridization, closely related species can be more similar to each other in areas of range overlap (parapatry or sympatry) than in areas where they are geographically isolated from each other (allopatry). Here, we report the reverse situation based on nuclear genetic divergence between two fir species, Abies chensiensis and Abies fargesii, in China, at sites where they are parapatric relative to where they are allopatric. We examined genetic divergence across 126 amplified fragment length polymorphism (AFLP) markers in a set of 172 individuals sampled from both allopatric and parapatric populations of the two species. Our analyses demonstrated that AFLP divergence was much greater between the species when comparisons were made between parapatric populations than between allopatric populations. We suggest that selection in parapatry may have largely contributed to this increased divergence. PMID:24772279

Description of the Magnetic Field and Divergence of Multisolenoid Aharonov-Bohm Potential

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Araz R. Aliev

2016-01-01

Full Text Available Explicit formulas for the magnetic field and divergence of multisolenoid Aharonov-Bohm potential are obtained; the mathematical essence of this potential is explained. It is shown that the magnetic field and divergence of this potential are very singular generalized functions concentrated at a finite number of thin solenoids. Deficiency index is found for the minimal operator generated by the Aharonov-Bohm differential expression.

Sensible and latent heat forced divergent circulations in the West African Monsoon System

Science.gov (United States)

Hagos, S.; Zhang, C.

2008-12-01

Field properties of divergent circulation are utilized to identify the roles of various diabatic processes in forcing moisture transport in the dynamics of the West African Monsoon and its seasonal cycle. In this analysis, the divergence field is treated as a set of point sources and is partitioned into two sub-sets corresponding to latent heat release and surface sensible heat flux at each respective point. The divergent circulation associated with each set is then calculated from the Poisson's equation using Gauss-Seidel iteration. Moisture transport by each set of divergent circulation is subsequently estimated. The results show different roles of the divergent circulations forced by surface sensible and latent heating in the monsoon dynamics. Surface sensible heating drives a shallow meridional circulation, which transports moisture deep into the continent at the polar side of the monsoon rain band and thereby promotes the seasonal northward migration of monsoon precipitation during the monsoon onset season. In contrast, the circulation directly associated with latent heating is deep and the corresponding moisture convergence is within the region of precipitation. Latent heating also induces dry air advection from the north. Neither effect promotes the seasonal northward migration of precipitation. The relative contributions of the processes associated with latent and sensible heating to the net moisture convergence, and hence the seasonal evolution of monsoon precipitation, depend on the background moisture.

Selection and geographic isolation influence hummingbird speciation: genetic, acoustic and morphological divergence in the wedge-tailed sabrewing (Campylopterus curvipennis

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Ornelas Juan

2011-02-01

Full Text Available Abstract Background Mesoamerica is one of the most threatened biodiversity hotspots in the world, yet we are far from understanding the geologic history and the processes driving population divergence and speciation for most endemic taxa. In species with highly differentiated populations selective and/or neutral factors can induce rapid changes to traits involved in mate choice, promoting reproductive isolation between allopatric populations that can eventually lead to speciation. We present the results of genetic differentiation, and explore drift and selection effects in promoting acoustic and morphological divergence among populations of Campylopterus curvipennis, a lekking hummingbird with an extraordinary vocal variability across Mesoamerica. Results Analyses of two mitochondrial genes and ten microsatellite loci genotyped for 160 individuals revealed the presence of three lineages with no contemporary gene flow: C. c. curvipennis, C. c. excellens, and C. c. pampa disjunctly distributed in the Sierra Madre Oriental, the Tuxtlas region and the Yucatan Peninsula, respectively. Sequence mtDNA and microsatellite data were congruent with two diversification events: an old vicariance event at the Isthmus of Tehuantepec (c. 1.4 Ma, and a more recent Pleistocene split, isolating populations in the Tuxtlas region. Hummingbirds of the excellens group were larger, and those of the pampa group had shorter bills, and lineages that have been isolated the longest shared fewer syllables and differed in spectral and temporal traits of a shared syllable. Coalescent simulations showed that fixation of song types has occurred faster than expected under neutrality but the null hypothesis that morphological divergence resulted from drift was not rejected. Conclusions Our phylogeographic analyses uncovered the presence of three Mesoamerican wedge-tailed sabrewing lineages, which diverged at different time scales. These results highlight the importance of the

The divergence theorem for unbounded vector fields

OpenAIRE

De Pauw, Thierry; Pfeffer, Washek F.

2007-01-01

In the context of Lebesgue integration, we derive the divergence theorem for unbounded vector. elds that can have singularities at every point of a compact set whose Minkowski content of codimension greater than two is. nite. The resulting integration by parts theorem is applied to removable sets of holomorphic and harmonic functions.

Complex patterns of genetic and phenotypic divergence in an island bird and the consequences for delimiting conservation units.

Science.gov (United States)

Phillimore, A B; Owens, I P F; Black, R A; Chittock, J; Burke, T; Clegg, S M

2008-06-01

Substantial phenotypic and genetic variation is often found below the species level and this may be useful in quantifying biodiversity and predicting future diversification. However, relatively few studies have tested whether different aspects of intraspecific variation show congruent patterns across populations. Here, we quantify several aspects of divergence between 13 insular populations of an island endemic bird, the Vanuatu white-eye (Zosterops flavifrons). The components of divergence studied are mitochondrial DNA (mtDNA), nuclear DNA microsatellites and morphology. These different aspects of divergence present subtly different scenarios. For instance, an mtDNA phylogenetic tree reveals a potential cryptic species on the most southerly island in Vanuatu and considerable divergence between at least two other major phylogroups. Microsatellite loci suggest that population genetic divergence between insular populations, both between and within phylogroups, is substantial, a result that is consistent with a low level of interisland gene flow. Finally, most populations were found to be strongly morphologically divergent, but no single population was morphologically diagnosable from all others. Taken together, our results show that, although many measures of divergence are concordant in this system, the number of divergent units identified varies widely depending on the characters considered and approach used. A continuum of divergence and a degree of discordance between different characters are both to be expected under simple models of evolution, but they present problems in terms of delimiting conservation units.

Initial States: IR and Collinear Divergences

International Nuclear Information System (INIS)

Lavelle, Martin; McMullan, David

2007-01-01

The standard approach to the infra-red problem is to use the Bloch-Nordsieck trick to handle soft divergences and the Lee-Nauenberg (LN) theorem for collinear singularities. We show that this is inconsistent in the presence of massless initial particles. Furthermore, we show that using the LN theorem with such initial states introduces a non-convergent infinite series of diagrams at any fixed order in perturbation theory

Change in Anopheles richness and composition in response to artificial flooding during the creation of the Jirau hydroelectric dam in Porto Velho, Brazil.

Science.gov (United States)

Rodrigures, Moreno S; Batista, Elis P; Silva, Alexandre A; Costa, Fábio M; Neto, Verissimo A S; Gil, Luiz Herman S

2017-02-22

Anopheles mosquitoes are the only vectors of human malaria. Anopheles species use standing water as breeding sites. Human activities, like the creation of an artificial lake during the implementation of hydroelectric power plants, lead to changes in environmental characteristics and, therefore, may changes the species richness and composition of Anopheles mosquitoes. The aim of the present study was to verify whether or not there is an association between the artificial flooding resulting from the construction of the Jirau hydroelectric power plant, and the richness and composition of anophelines. Mosquitoes samples were obtained monthly from the Jirau hydroelectric power plant area located at Porto Velho, Rondônia State, using Human Landing Catch (06:00-10:00 PM). Mosquitoes collected were transported to Laboratório de Entomologia Médica FIOCRUZ-RO where they were identified until species using dichotomous key. A total of 6347 anophelines belonging to eight different species were collected. The anophelines species richness was significantly lower during the first flooding stage. Differences in anophelines species composition were found when comparing the first flooding stage with the other stages. Furthermore, the mean number of Anopheles darlingi, the main vector of malaria in the region, increases during the first and the third flooding stages. The continual monitoring of these vectors during the late operational phase may be useful in order to understand how anophelines will behave in this area.

Differential Modulation of Performance in Insight and Divergent Thinking Tasks with tDCS

Science.gov (United States)

Goel, Vinod; Eimontaite, Iveta; Goel, Amit; Schindler, Igor

2015-01-01

While both insight and divergent thinking tasks are used to study creativity, there are reasons to believe that the two may call upon very different mechanisms. To explore this hypothesis, we administered a verbal insight task (riddles) and a divergent thinking task (verbal fluency) to 16 native English speakers and 16 non-native English speakers…

Divergent growth of Norway spruce on Babia Góra Mountain in the western Carpathians

NARCIS (Netherlands)

Buras, Allan; Spyt, Barbara; Janecka, Karolina; Kaczka, Ryszard

2018-01-01

Growth divergence – i.e. the expression of divergent growth trends of neighboring trees – has certain implications for dendrochronological research, for instance in the context of climate reconstructions but also in terms of estimating net ecosystem productivity. Thus, understanding the underlying

Hybrid Smith predictor and phase lead based divergence compensation for hardware-in-the-loop contact simulation with measurement delay

Science.gov (United States)

Qi, Chenkun; Gao, Feng; Zhao, Xianchao; Wang, Qian; Ren, Anye

2018-06-01

On the ground the hardware-in-the-loop (HIL) simulation is a good approach to test the contact dynamics of spacecraft docking process in space. Unfortunately, due to the time delay in the system the HIL contact simulation becomes divergent. However, the traditional first-order phase lead compensation approach still result in a small divergence for the pure time delay. The serial Smith predictor and phase lead compensation approach proposed by the authors recently will lead to an over-compensation and an obvious convergence. In this study, a hybrid Smith predictor and phase lead compensation approach is proposed. The hybrid Smith predictor and phase lead compensation can achieve a higher simulation fidelity with a little convergence. The phase angle of the compensator is analyzed and the stability condition of the HIL simulation system is given. The effectiveness of the proposed compensation approach is tested by simulations on an undamped elastic contact process.

Convergence and divergence, a concept for explaining drug actions.

Science.gov (United States)

Watanabe, Takehiko; Kamisaki, Yoshinori; Timmerman, Henk

2004-10-01

For the teaching and/or learning about drug actions and for the discovery and development of new drugs, it is important to understand how drugs act on living bodies. So far, there has been no clear description on the general principle of drug action in pharmacology textbooks. We propose two principles to depict the action mechanism of drugs. The first is that most, if not all, drugs act on proteins at the molecular level, that is, enzymes, receptors, ion channels, and transporters. The second is that a drug may cause divergent or convergent responses, resulting in changes of a physiological or pathological function of the human body. The concept of divergence and convergence can be used to explain the complex individuality of drug actions.

Several one-loop calculations in a formulation of massive quantum electrodynamics possessing only vacuum-polarization divergences

International Nuclear Information System (INIS)

Phillips, S.

1985-01-01

An alternative formulation of path-integral quantization for gauge theories is proposed in which the gauge-fixing condition, normally imposed on just the gauge field itself, is imposed on the gauge-transformed gauge field, a continuous sum now being included over all configurations of the transformation field, Λ(x) that satisfy the gauge condition. It is shown, by explicit calculation, that when bilinear counterterms in the Lagrangian field density are included so as to render the two-point gauge- and fermion-field Green's functions finite, the fermion-fermion-gauge-field Green's function is divergence free. Unlike the more conventional approaches, there is no divergent vertex counterterm needed. Furthermore, the form of the fermion counterterm is a simple mass insertion only. There is no need for a divergent fermion wave-function renormalization. The cancellation of the divergences that are normally present is accomplished by the effect of, heretofor uncommon in perturbative quantum-field theory, infrared-divergent integrals. It is argued heuristically how these may be regulated by the same parameter, Λ, that is used for ultraviolet-divergent integrals, where now the cutoff is towards the lower limit of integration

A possible explanation for the divergent projection of ENSO amplitude change under global warming

Science.gov (United States)

Chen, Lin; Li, Tim; Yu, Yongqiang; Behera, Swadhin K.

2017-12-01

The El Niño-Southern Oscillation (ENSO) is the greatest climate variability on interannual time scale, yet what controls ENSO amplitude changes under global warming (GW) is uncertain. Here we show that the fundamental factor that controls the divergent projections of ENSO amplitude change within 20 coupled general circulation models that participated in the Coupled Model Intercomparison Project phase-5 is the change of climatologic mean Pacific subtropical cell (STC), whose strength determines the meridional structure of ENSO perturbations and thus the anomalous thermocline response to the wind forcing. The change of the thermocline response is a key factor regulating the strength of Bjerknes thermocline and zonal advective feedbacks, which ultimately lead to the divergent changes in ENSO amplitude. Furthermore, by forcing an ocean general circulation mode with the change of zonal mean zonal wind stress estimated by a simple theoretical model, a weakening of the STC in future is obtained. Such a change implies that ENSO variability might strengthen under GW, which could have a profound socio-economic consequence.

Interplay of Proximal Flow Confluence and Distal Flow Divergence in Patient-Specific Vertebrobasilar System.

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Xiaoping Yin

Full Text Available Approximately one-quarter of ischemic strokes involve the vertebrobasilar arterial system that includes the upstream flow confluence and downstream flow divergence. A patient-specific hemodynamic analysis is needed to understand the posterior circulation. The objective of this study is to determine the distribution of hemodynamic parameters in the vertebrobasilar system, based on computer tomography angiography images. Here, the interplay of upstream flow confluence and downstream flow divergence was hypothesized to be a determinant factor for the hemodynamic distribution in the vertebrobasilar system. A computational fluid dynamics model was used to compute the flow fields in patient-specific vertebrobasilar models (n = 6. The inlet and outlet boundary conditions were the aortic pressure waveform and flow resistances, respectively. A 50% reduction of total outlet area was found to induce a ten-fold increase in surface area ratio of low time-averaged wall shear stress (i.e., TAWSS ≤ 4 dynes/cm2. This study enhances our understanding of the posterior circulation associated with the incidence of atherosclerotic plaques.

Changes in cis-regulatory elements of a key floral regulator are associated with divergence of inflorescence architectures.

Science.gov (United States)

Kusters, Elske; Della Pina, Serena; Castel, Rob; Souer, Erik; Koes, Ronald

2015-08-15

Higher plant species diverged extensively with regard to the moment (flowering time) and position (inflorescence architecture) at which flowers are formed. This seems largely caused by variation in the expression patterns of conserved genes that specify floral meristem identity (FMI), rather than changes in the encoded proteins. Here, we report a functional comparison of the promoters of homologous FMI genes from Arabidopsis, petunia, tomato and Antirrhinum. Analysis of promoter-reporter constructs in petunia and Arabidopsis, as well as complementation experiments, showed that the divergent expression of leafy (LFY) and the petunia homolog aberrant leaf and flower (ALF) results from alterations in the upstream regulatory network rather than cis-regulatory changes. The divergent expression of unusual floral organs (UFO) from Arabidopsis, and the petunia homolog double top (DOT), however, is caused by the loss or gain of cis-regulatory promoter elements, which respond to trans-acting factors that are expressed in similar patterns in both species. Introduction of pUFO:UFO causes no obvious defects in Arabidopsis, but in petunia it causes the precocious and ectopic formation of flowers. This provides an example of how a change in a cis-regulatory region can account for a change in the plant body plan. © 2015. Published by The Company of Biologists Ltd.

The Harmonic Series Diverges Again and Again

Science.gov (United States)

Kifowit, Steven J.; Stamps, Terra A.

2006-01-01

The harmonic series is one of the most celebrated infinite series of mathematics. A quick glance at a variety of modern calculus textbooks reveals that there are two very popular proofs of the divergence of the harmonic series. In this article, the authors survey these popular proofs along with many other proofs that are equally simple and…

Factor analysis models via I-divergence optimization

NARCIS (Netherlands)

Finesso, L.; Spreij, P.

2016-01-01

Given a positive definite covariance matrix Σˆ of dimension n, we approximate it with a covariance of the form HH⊤+D, where H has a prescribed number k0 is diagonal. The quality of the approximation is gauged by the I-divergence between the zero mean normal laws with covariances

Dissecting molecular stress networks: identifying nodes of divergence between life-history phenotypes.

Science.gov (United States)

Schwartz, Tonia S; Bronikowski, Anne M

2013-02-01

The complex molecular network that underlies physiological stress response is comprised of nodes (proteins, metabolites, mRNAs, etc.) whose connections span cells, tissues and organs. Variable nodes are points in the network upon which natural selection may act. Thus, identifying variable nodes will reveal how this molecular stress network may evolve among populations in different habitats and how it might impact life-history evolution. Here, we use physiological and genetic assays to test whether laboratory-born juveniles from natural populations of garter snakes (Thamnophis elegans), which have diverged in their life-history phenotypes, vary concomitantly at candidate nodes of the stress response network, (i) under unstressed conditions and (ii) in response to an induced stress. We found that two common measures of stress (plasma corticosterone and liver gene expression of heat shock proteins) increased under stress in both life-history phenotypes. In contrast, the phenotypes diverged at four nodes both under unstressed conditions and in response to stress: circulating levels of reactive oxygen species (superoxide, H(2)O(2)); liver gene expression of GPX1 and erythrocyte DNA damage. Additionally, allele frequencies for SOD2 diverge from neutral markers, suggesting diversifying selection on SOD2 alleles. This study supports the hypothesis that these life-history phenotypes have diverged at the molecular level in how they respond to stress, particularly in nodes regulating oxidative stress. Furthermore, the differences between the life-history phenotypes were more pronounced in females. We discuss the responses to stress in the context of the associated life-history phenotype and the evolutionary pressures thought to be responsible for divergence between the phenotypes. © 2012 Blackwell Publishing Ltd.

Flutter and divergence instability of supported piezoelectric nanotubes conveying fluid

Science.gov (United States)

Bahaadini, Reza; Hosseini, Mohammad; Jamali, Behnam

2018-01-01

In this paper, divergence and flutter instabilities of supported piezoelectric nanotubes containing flowing fluid are investigated. To take the size effects into account, the nonlocal elasticity theory is implemented in conjunction with the Euler-Bernoulli beam theory incorporating surface stress effects. The Knudsen number is applied to investigate the slip boundary conditions between the flow and wall of nanotube. The nonlocal governing equations of nanotube are obtained using Newtonian method, including the influence of piezoelectric voltage, surface effects, Knudsen number and nonlocal parameter. Applying Galerkin approach to transform resulting equations into a set of eigenvalue equations under the simple-simple (S-S) and clamped-clamped (C-C) boundary conditions. The effects of the piezoelectric voltage, surface effects, Knudsen number, nonlocal parameter and boundary conditions on the divergence and flutter boundaries of nanotubes are discussed. It is observed that the fluid-conveying nanotubes with both ends supported lose their stability by divergence first and then by flutter with increase in fluid velocity. Results indicate the importance of using piezoelectric voltage, nonlocal parameter and Knudsen number in decrease of critical flow velocities of system. Moreover, the surface effects have a significant role on the eigenfrequencies and critical fluid velocity.

Numerical simulation of divergent rocket-based-combined-cycle performances under the flight condition of Mach 3

Science.gov (United States)

Cui, Peng; Xu, WanWu; Li, Qinglian

2018-01-01

Currently, the upper operating limit of the turbine engine is Mach 2+, and the lower limit of the dual-mode scramjet is Mach 4. Therefore no single power systems can operate within the range between Mach 2 + and Mach 4. By using ejector rockets, Rocket-based-combined-cycle can work well in the above scope. As the key component of Rocket-based-combined-cycle, the ejector rocket has significant influence on Rocket-based-combined-cycle performance. Research on the influence of rocket parameters on Rocket-based-combined-cycle in the speed range of Mach 2 + to Mach 4 is scarce. In the present study, influences of Mach number and total pressure of the ejector rocket on Rocket-based-combined-cycle were analyzed numerically. Due to the significant effects of the flight conditions and the Rocket-based-combined-cycle configuration on Rocket-based-combined-cycle performances, flight altitude, flight Mach number, and divergence ratio were also considered. The simulation results indicate that matching lower altitude with higher flight Mach numbers can increase Rocket-based-combined-cycle thrust. For another thing, with an increase of the divergent ratio, the effect of the divergent configuration will strengthen and there is a limit on the divergent ratio. When the divergent ratio is greater than the limit, the effect of divergent configuration will gradually exceed that of combustion on supersonic flows. Further increases in the divergent ratio will decrease Rocket-based-combined-cycle thrust.

Genetic Coupling of Female Mate Choice with Polygenic Ecological Divergence Facilitates Stickleback Speciation.

Science.gov (United States)

Bay, Rachael A; Arnegard, Matthew E; Conte, Gina L; Best, Jacob; Bedford, Nicole L; McCann, Shaugnessy R; Dubin, Matthew E; Chan, Yingguang Frank; Jones, Felicity C; Kingsley, David M; Schluter, Dolph; Peichel, Catherine L

2017-11-06

Ecological speciation with gene flow is widespread in nature [1], but it presents a conundrum: how are associations between traits under divergent natural selection and traits that contribute to assortative mating maintained? Theoretical models suggest that genetic mechanisms inhibiting free recombination between loci underlying these two types of traits (hereafter, "genetic coupling") can facilitate speciation [2-4]. Here, we perform a direct test for genetic coupling by mapping both divergent traits and female mate choice in a classic model of ecological speciation: sympatric benthic and limnetic threespine stickleback (Gasterosteus aculeatus). By measuring mate choice in F2 hybrid females, we allowed for recombination between loci underlying assortative mating and those under divergent ecological selection. In semi-natural mating arenas in which females had access to both benthic and limnetic males, we found that F2 females mated with males similar to themselves in body size and shape. In addition, we found two quantitative trait loci (QTLs) associated with female mate choice that also predicted female morphology along the benthic-limnetic trait axis. Furthermore, a polygenic genetic model that explains adaptation to contrasting benthic and limnetic feeding niches [5] also predicted F2 female mate choice. Together, these results provide empirical evidence that genetic coupling of assortative mating with traits under divergent ecological selection helps maintain species in the face of gene flow, despite a polygenic basis for adaptation to divergent environments. Copyright © 2017 Elsevier Ltd. All rights reserved.

Divergence of sun-rays by atmospheric refraction at large solar zenith angles

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R. Uhl

2004-01-01

Full Text Available For the determination of photolysis rates at large zenith angles it has been demonstrated that refraction by the earth's atmosphere must be taken into account. In fact, due to the modified optical path the optical transmittance is thereby increased in most instances. Here we show that in addition the divergence of sun-rays, which is also caused by refraction but which reduces the direct solar irradiance, should not be neglected. Our calculations are based on a spherically symmetric atmosphere and include extinction by Rayleigh scattering, ozone, and background aerosol. For rays with 10km tangent altitude the divergence yields a reduction of about 10% to 40% at solar zenith angles of 91° to 96°. Moreover, we find that the divergence effect can completely cancel the relative enhancement caused by the increase of transmittance.

Measurements of the divergence of fast electrons in laser-irradiated spherical targets

International Nuclear Information System (INIS)

Yaakobi, B.; Solodov, A. A.; Myatt, J. F.; Delettrez, J. A.; Stoeckl, C.; Froula, D. H.

2013-01-01

In recent experiments using directly driven spherical targets on the OMEGA laser system, the energy in fast electrons was found to reach ∼1% of the laser energy at an irradiance of ∼1.1 × 10 15 W/cm 2 . The fraction of these fast electrons absorbed in the compressed fuel shell depends on their angular divergence. This paper describes measurements of this divergence deduced from a series of shots where Mo-coated shells of increasing diameter (D) were suspended within an outer CH shell. The intensity of the Mo–Kα line and the hard x-ray radiation were found to increase approximately as ∼D 2 , indicating wide divergence of the fast electrons. Alternative interpretations of these results (electron scattering, radiation excitation of Kα, and an electric field due to return current) are shown to be unimportant

Dynamical renormalization group resummation of finite temperature infrared divergences

International Nuclear Information System (INIS)

Boyanovsky, D.; Vega, H.J. de; Boyanovsky, D.; Simionato, M.; Holman, R.; Simionato, M.

1999-01-01

We introduce the method of dynamical renormalization group to study relaxation and damping out of equilibrium directly in real time and apply it to the study of infrared divergences in scalar QED. This method allows a consistent resummation of infrared effects associated with the exchange of quasistatic transverse photons and leads to anomalous logarithmic relaxation of the form e -αampersandhthinsp;Tampersandhthinsp;tampersandhthinsp;ln[t/t 0 ] for hard momentum charged excitations. This is in contrast with the usual quasiparticle interpretation of charged collective excitations at finite temperature in the sense of exponential relaxation of a narrow width resonance for which the width is the imaginary part of the self-energy on shell. In the case of narrow resonances away from thresholds, this approach leads to the usual exponential relaxation. The hard thermal loop resummation program is incorporated consistently into the dynamical renormalization group yielding a picture of relaxation and damping phenomena in a plasma in real time that transcends the conceptual limitations of the quasiparticle picture and other types of resummation schemes. copyright 1999 The American Physical Society

Zimmermann's forest formula, infrared divergences and the QCD beta function

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Franz Herzog

2018-01-01

Full Text Available We review Zimmermann's forest formula, which solves Bogoliubov's recursive R-operation for the subtraction of ultraviolet divergences in perturbative Quantum Field Theory. We further discuss a generalisation of the R-operation which subtracts besides ultraviolet also Euclidean infrared divergences. This generalisation, which goes under the name of the R⁎-operation, can be used efficiently to compute renormalisation constants. We will discuss several results obtained by this method with focus on the QCD beta function at five loops as well as the application to hadronic Higgs boson decay rates at N4LO. This article summarizes a talk given at the Wolfhart Zimmermann Memorial Symposium.

Monoparametric family of metrics derived from classical Jensen-Shannon divergence

Science.gov (United States)

Osán, Tristán M.; Bussandri, Diego G.; Lamberti, Pedro W.

2018-04-01

Jensen-Shannon divergence is a well known multi-purpose measure of dissimilarity between probability distributions. It has been proven that the square root of this quantity is a true metric in the sense that, in addition to the basic properties of a distance, it also satisfies the triangle inequality. In this work we extend this last result to prove that in fact it is possible to derive a monoparametric family of metrics from the classical Jensen-Shannon divergence. Motivated by our results, an application into the field of symbolic sequences segmentation is explored. Additionally, we analyze the possibility to extend this result into the quantum realm.

Infrared divergences for free quantum fields in cosmological spacetimes

Science.gov (United States)

Higuchi, Atsushi; Rendell, Nicola

2018-06-01

We investigate the nature of infrared divergences for the free graviton and inflaton two-point functions in flat Friedman–Lemaître–Robertson–Walker spacetime. These divergences arise because the momentum integral for these two-point functions diverges in the infrared. It is straightforward to see that the power of the momentum in the integrand can be increased by 2 in the infrared using large gauge transformations, which are sufficient for rendering these two-point functions infrared finite for slow-roll inflation. In other words, if the integrand of the momentum integral for these two-point functions behaves like , where p is the momentum, in the infrared, then it can be made to behave like by large gauge transformations. On the other hand, it is known that, if one smears these two-point functions in a gauge-invariant manner, the power of the momentum in the integrand is changed from to . This fact suggests that the power of the momentum in the integrand for these two-point functions can be increased by 4 using large gauge transformations. In this paper we show that this is indeed the case. Thus, the two-point functions for the graviton and inflaton fields can be made finite by large gauge transformations for a large class of potentials and states in single-field inflation.

Sand-mediated divergence between shallow reef communities on ...

African Journals Online (AJOL)

Sand-mediated divergence between shallow reef communities on horizontal and vertical substrata in the western Indian Ocean. SN Porter, GM Branch, KJ Sink. Abstract. Distinctions are rarely made between vertical and horizontal surfaces when assessing reef community composition, yet physical differences are expected ...

Kullback–Leibler Divergence of the γ–ordered Normal over t–distribution

OpenAIRE

Toulias, T-L.; Kitsos, C-P.

2012-01-01

The aim of this paper is to evaluate and study the Kullback–Leibler divergence of the γ–ordered Normal distribution, a generalization of Normal distribution emerged from the generalized Fisher’s information measure, over the scaled t–distribution. We investigate this evaluation through a series of bounds and approximations while the asymptotic behavior of the divergence is also studied. Moreover, we obtain a generalization of the known Kullback–Leibler information measure betwe...

[Ontogenetic Mechanisms of Explosive Morphological Divergence in the Lake Tana (Ethiopia) Species Flock of Large African Barbs (Labeobarbus; Cyprinidae; Teleostei)].

Science.gov (United States)

Shkila, F N; Lazebny, O E; Kapitanova, D V; Abdissa, Belay; Borisov, V B; Smirnov, S V

2015-01-01

Species flock of Lake Tana (Ethiopia) large African barbs (Labeobarbus; Cyprinidae; Teleostei) was studied as a model system for investigating ontogenetic mechanisms of the explosive morphological divergence often accompanying sympatric speciation in bony fishes. Comparative morphological analysis carried out with the use ofgeometric morphometric techniques revealed quantitative differences in the head shapes of species under study. Comparative analysis of skull development revealed significant interspecies differences in the temporal characteristics of craniogenesis in these species. These two lines of evidence suggest that heterochronies in craniogenesis underlie divergence in the head shapes of adult Tana barbs. This prediction was verified via experimental changes of temporal characteristics of craniogenesis in L. intermedius, a putative ancestor for the Lake Tana species flock. For this aim, timing and rate of skull development were changed by artificial manipulation of thyroid hormone levels. In sum, it was shown that it is heterochronies that underlie an explosive morphological divergence of the Lake Tana barbs species flock. Our findings together with those reported in the literature suggest variability in the activity of the hypothalamic-pituitary-thyroid axis to contribute to these heterochronies.

Genetic Divergence in Eucalyptus camaldulensis Progenies in the Savanna Biome in Mato Grosso, Brazil.

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Reginaldo Brito da Costa

Full Text Available Assessing the parental genetic differences and their subsequent prediction of progeny performance is an important first step to assure the efficiency of any breeding program. In this study, we estimate the genetic divergence in Eucalyptus camaldulensis based on the morphological traits of 132 progenies grown in a savanna biome. Thus, a field experiment was performed using a randomized block design and five replications to compare divergences in total height, commercial height, diameter at breast height, stem form and survival rate at 48 months. Tocher's clustering method was performed using the Mahalanobis and Euclidian distances. The Mahalanobis distance seemed more reliable for the assessed parameters and clustered all of the progenies into fourteen major groups. The most similar progenies (86 accessions were clustered into Group I, while the most dissimilar (1 progeny represented Group XIV. The divergence analysis indicated that promising crosses could be made between progenies allocated in different groups for high genetic divergence and for favorable morphological traits.

Avaliação da divergência nutricional de variedades de cana-de-açúcar (Saccharum spp. Evaluation of the nutritional divergence of the sugarcane (Saccharum spp. varieties

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José Augusto Gomes Azevêdo

2003-12-01

-1763, SP80-4445, SP79-1011, RB739359, RB867515 and SP80-3280, harvested at 426, 487 and 549 days post planting. Neutral detergent fiber (NDF, hemicellulose, lignin, undegradable NDF fraction and degradation rate of the potentially degradable NDF fraction were the evaluated discriminatory variables. Differences were observed for all the studied variables, except for the undegradable NDF fraction. The evaluation of the nutritional divergence of the sugarcane varieties based on the first three principal components, that explained 87.8% of the total variation. The NDF and the undegradable NDF fraction were the variables of smaller importance to explain the nutritional variability of the varieties. The SP80-1842 variety, harvested at 426 days post planting, and SP79-1011 variety, harvested at 549 days, were the ones that showed greater score dispersions for the first three principal components, being considered the most dissimilar, while the RB845257 variety, harvested at 487 days post planting, was located in the intermediary position between both. The principal components analysis was also efficient in selecting varieties with different harvesting times.

A novel methodology to determine the divergence of a neutron beam

Energy Technology Data Exchange (ETDEWEB)

Souza, E.S., E-mail: msouza@ien.gov.br [Universidade Federal do Rio de Janeiro, COPPE, Centro de Tecnologia, Cidade Universitaria, Bloco G, Ilha do Fundao, 21945-970 Rio de Janeiro, RJ (Brazil); Almeida, G.L., E-mail: gevlisb@hotmail.com [Instituto de Engenharia Nuclear, Reator Argonauta - CNEN Rua Helio de Almeida 75, Cidade Universitária, Ilha do Fundao, Caixa Postal 68550, CEP 21941-972 Rio de Janeiro, RJ (Brazil); Lopes, R.T., E-mail: ricardo@lin.ufrj.br [Universidade Federal do Rio de Janeiro, COPPE, Centro de Tecnologia, Cidade Universitaria, Bloco G, Ilha do Fundao, 21945-970 Rio de Janeiro, RJ (Brazil)

2016-12-01

This work posits a novel approach to characterize the divergence of a neutron beam emerging from a reactor port. Unlike the usual inverse of the L/D ratio, the term divergence as employed here refers to the deviation from an ideal parallel beam emitted from a surface source. Within this concept, an ideal point source in spite of its conical beam would not exhibit any divergence. Hence, the beam divergence of a surface source is more adequately characterized adopting the notion of Rocking Curve - RC, a term borrowed from the X-ray diffraction field. After this idea, every point of the surface source emits neutrons in all directions but with different intensities following a bell-shaped profile. Once the RC semi-width is determined, it is possible to assess its effect upon the quality of an acquired neutron radiograph, since it incorporates degrading agents such as geometrical unsharpness, neutron scattering, noise and statistical dispersion. In this work an inverse procedure is applied, i.e., to use an actual neutron radiograph to find the RC semi-width. To accomplish this task, synthetic images - generated with defined RC semi-widths and object-detector gaps - are compared with experimental ones acquired with the same gaps in order to find the most resemblance between them. The angular semi-width of the best synthetic image is assigned to that of the experimental one, defining thus the aimed beam divergence, which has been compared with a different method with a fair agreement. An equivalent procedure embedded in the algorithm has been employed to evaluate the L/D using the same radiographic images. The outcome fairly agrees with the value inferred from the neutron flux ratio at different locations. Both approaches RC semi-width and L/D ratio yielded consistent results with other utterly different methods. Yet, the rocking curve approach forecasts more precisely the neutron pattern hitting the detector and does not need a precisely machined test-object as required

A novel methodology to determine the divergence of a neutron beam

International Nuclear Information System (INIS)

Souza, E.S.; Almeida, G.L.; Lopes, R.T.

2016-01-01

This work posits a novel approach to characterize the divergence of a neutron beam emerging from a reactor port. Unlike the usual inverse of the L/D ratio, the term divergence as employed here refers to the deviation from an ideal parallel beam emitted from a surface source. Within this concept, an ideal point source in spite of its conical beam would not exhibit any divergence. Hence, the beam divergence of a surface source is more adequately characterized adopting the notion of Rocking Curve - RC, a term borrowed from the X-ray diffraction field. After this idea, every point of the surface source emits neutrons in all directions but with different intensities following a bell-shaped profile. Once the RC semi-width is determined, it is possible to assess its effect upon the quality of an acquired neutron radiograph, since it incorporates degrading agents such as geometrical unsharpness, neutron scattering, noise and statistical dispersion. In this work an inverse procedure is applied, i.e., to use an actual neutron radiograph to find the RC semi-width. To accomplish this task, synthetic images - generated with defined RC semi-widths and object-detector gaps - are compared with experimental ones acquired with the same gaps in order to find the most resemblance between them. The angular semi-width of the best synthetic image is assigned to that of the experimental one, defining thus the aimed beam divergence, which has been compared with a different method with a fair agreement. An equivalent procedure embedded in the algorithm has been employed to evaluate the L/D using the same radiographic images. The outcome fairly agrees with the value inferred from the neutron flux ratio at different locations. Both approaches RC semi-width and L/D ratio yielded consistent results with other utterly different methods. Yet, the rocking curve approach forecasts more precisely the neutron pattern hitting the detector and does not need a precisely machined test-object as required

Divergent apparent temperature sensitivity of terrestrial ecosystem respiration

Science.gov (United States)

Bing Song; Shuli Niu; Ruise Luo; Yiqi Luo; Jiquan Chen; Guirui Yu; Janusz Olejnik; Georg Wohlfahrt; Gerard Kiely; Ako Noormets; Leonardo Montagnani; Alessandro Cescatti; Vincenzo Magliulo; Beverly Elizabeth Law; Magnus Lund; Andrej Varlagin; Antonio Raschi; Matthias Peichl; Mats B. Nilsson; Lutz Merbold

2014-01-01

Recent studies revealed convergent temperature sensitivity of ecosystem respiration (Re) within aquatic ecosystems and between terrestrial and aquatic ecosystems. We do not know yet whether various terrestrial ecosystems have consistent or divergent temperature sensitivity. Here, we synthesized 163 eddy covariance flux sites across the world and...

Divergence of perturbation theory in large scale structures

Science.gov (United States)

Pajer, Enrico; van der Woude, Drian

2018-05-01

We make progress towards an analytical understanding of the regime of validity of perturbation theory for large scale structures and the nature of some non-perturbative corrections. We restrict ourselves to 1D gravitational collapse, for which exact solutions before shell crossing are known. We review the convergence of perturbation theory for the power spectrum, recently proven by McQuinn and White [1], and extend it to non-Gaussian initial conditions and the bispectrum. In contrast, we prove that perturbation theory diverges for the real space two-point correlation function and for the probability density function (PDF) of the density averaged in cells and all the cumulants derived from it. We attribute these divergences to the statistical averaging intrinsic to cosmological observables, which, even on very large and "perturbative" scales, gives non-vanishing weight to all extreme fluctuations. Finally, we discuss some general properties of non-perturbative effects in real space and Fourier space.

Toxic hydrogen sulfide and dark caves: phenotypic and genetic divergence across two abiotic environmental gradients in Poecilia mexicana.

Science.gov (United States)

Tobler, Michael; Dewitt, Thomas J; Schlupp, Ingo; García de León, Francisco J; Herrmann, Roger; Feulner, Philine G D; Tiedemann, Ralph; Plath, Martin

2008-10-01

Divergent natural selection drives evolutionary diversification. It creates phenotypic diversity by favoring developmental plasticity within populations or genetic differentiation and local adaptation among populations. We investigated phenotypic and genetic divergence in the livebearing fish Poecilia mexicana along two abiotic environmental gradients. These fish typically inhabit nonsulfidic surface rivers, but also colonized sulfidic and cave habitats. We assessed phenotypic variation among a factorial combination of habitat types using geometric and traditional morphometrics, and genetic divergence using quantitative and molecular genetic analyses. Fish in caves (sulfidic or not) exhibited reduced eyes and slender bodies. Fish from sulfidic habitats (surface or cave) exhibited larger heads and longer gill filaments. Common-garden rearing suggested that these morphological differences are partly heritable. Population genetic analyses using microsatellites as well as cytochrome b gene sequences indicate high population differentiation over small spatial scale and very low rates of gene flow, especially among different habitat types. This suggests that divergent environmental conditions constitute barriers to gene flow. Strong molecular divergence over short distances as well as phenotypic and quantitative genetic divergence across habitats in directions classic to fish ecomorphology suggest that divergent selection is structuring phenotypic variation in this system.

COMPARATIVE FINANCIAL STATEMENTS. CONVERGENCE VERSUS DIVERGENCE

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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.

Identifying malaria vector breeding habitats with remote sensing data and terrain-based landscape indices in Zambia

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Shiff Clive

2010-11-01

Full Text Available Abstract Background Malaria, caused by the parasite Plasmodium falciparum, is a significant source of morbidity and mortality in southern Zambia. In the Mapanza Chiefdom, where transmission is seasonal, Anopheles arabiensis is the dominant malaria vector. The ability to predict larval habitats can help focus control measures. Methods A survey was conducted in March-April 2007, at the end of the rainy season, to identify and map locations of water pooling and the occurrence anopheline larval habitats; this was repeated in October 2007 at the end of the dry season and in March-April 2008 during the next rainy season. Logistic regression and generalized linear mixed modeling were applied to assess the predictive value of terrain-based landscape indices along with LandSat imagery to identify aquatic habitats and, especially, those with anopheline mosquito larvae. Results Approximately two hundred aquatic habitat sites were identified with 69 percent positive for anopheline mosquitoes. Nine species of anopheline mosquitoes were identified, of which, 19% were An. arabiensis. Terrain-based landscape indices combined with LandSat predicted sites with water, sites with anopheline mosquitoes and sites specifically with An. arabiensis. These models were especially successful at ruling out potential locations, but had limited ability in predicting which anopheline species inhabited aquatic sites. Terrain indices derived from 90 meter Shuttle Radar Topography Mission (SRTM digital elevation data (DEM were better at predicting water drainage patterns and characterizing the landscape than those derived from 30 m Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER DEM. Conclusions The low number of aquatic habitats available and the ability to locate the limited number of aquatic habitat locations for surveillance, especially those containing anopheline larvae, suggest that larval control maybe a cost-effective control measure in the fight

Identifying malaria vector breeding habitats with remote sensing data and terrain-based landscape indices in Zambia.

Science.gov (United States)

Clennon, Julie A; Kamanga, Aniset; Musapa, Mulenga; Shiff, Clive; Glass, Gregory E

2010-11-05

Malaria, caused by the parasite Plasmodium falciparum, is a significant source of morbidity and mortality in southern Zambia. In the Mapanza Chiefdom, where transmission is seasonal, Anopheles arabiensis is the dominant malaria vector. The ability to predict larval habitats can help focus control measures. A survey was conducted in March-April 2007, at the end of the rainy season, to identify and map locations of water pooling and the occurrence anopheline larval habitats; this was repeated in October 2007 at the end of the dry season and in March-April 2008 during the next rainy season. Logistic regression and generalized linear mixed modeling were applied to assess the predictive value of terrain-based landscape indices along with LandSat imagery to identify aquatic habitats and, especially, those with anopheline mosquito larvae. Approximately two hundred aquatic habitat sites were identified with 69 percent positive for anopheline mosquitoes. Nine species of anopheline mosquitoes were identified, of which, 19% were An. arabiensis. Terrain-based landscape indices combined with LandSat predicted sites with water, sites with anopheline mosquitoes and sites specifically with An. arabiensis. These models were especially successful at ruling out potential locations, but had limited ability in predicting which anopheline species inhabited aquatic sites. Terrain indices derived from 90 meter Shuttle Radar Topography Mission (SRTM) digital elevation data (DEM) were better at predicting water drainage patterns and characterizing the landscape than those derived from 30 m Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) DEM. The low number of aquatic habitats available and the ability to locate the limited number of aquatic habitat locations for surveillance, especially those containing anopheline larvae, suggest that larval control maybe a cost-effective control measure in the fight against malaria in Zambia and other regions with seasonal

Typing Speed as a Confounding Variable and the Measurement of Quality in Divergent Thinking

Science.gov (United States)

Forthmann, Boris; Holling, Heinz; Çelik, Pinar; Storme, Martin; Lubart, Todd

2017-01-01

The need to control for writing or typing speed when assessing divergent-thinking performance has been recognized since the early '90s. An even longer tradition in divergent-thinking research has the issue of scoring the responses for quality. This research addressed both issues within structural equation modeling. Three dimensions of…

Divergence and genetic variability among superior rubber tree genotypes Divergência e variabilidade genética de genótipos superiores de seringueira

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Lígia Regina Lima Gouvêa

2010-02-01

Full Text Available The objective of this work was to estimate the genetic variability and divergence among 22 superior rubber tree (Hevea sp. genotypes of the IAC 400 series. Univariate and multivariate analyses were performed using eight quantitative traits (descriptors, including yield. In the univariate analyses, the estimated parameters were: genetic and environmental variances; genetic and environmental coefficients of variation; and the variation index. The Mahalanobis generalized distance, the Tocher agglomerative method and canonical variables were used for the multivariate analyses. In the univariate analyses, variability was verified among the genotypes for all the variables evaluated. The Tocher method grouped the genotypes into 11 clusters of dissimilarity. The first four canonical variables explained 87.93% of the cumulative variation. The highest genetic variability was found in rubber yield-related traits, which contributed the most to the genetic divergence. The most divergent pairs of genotypes are suggested for crossbreeding. The genotypes evaluated are suitable for breeding and may be used to continue the IAC rubber tree breeding program.O objetivo deste trabalho foi estimar a divergência e a variabilidade genética entre 22 genótipos superiores de seringueira (Hevea sp. da série IAC 400. Análises univariadas e multivariadas foram realizadas com oito caracteres quantitativos (descritores, incluindo produtividade. Na análise univariada, os parâmetros estimados foram: variâncias genética e ambiental, coeficientes de variação genética e ambiental, e índice de variação. A distância generalizada de Mahalanobis, o método aglomerativo de Tocher e variáveis canônicas foram utilizados nas análises multivariadas. Nas análises univariadas, verificou-se variabilidade entre os genótipos para todas as variáveis avaliadas. O método de Tocher agrupou os genótipos em 11 grupos de dissimilaridade. As quatro primeiras variáveis can

Influence of divergent and convergent thinking on visuomotor adaptation in young and older adults.

Science.gov (United States)

Simon, Anja; Bock, Otmar

2016-04-01

Visuomotor adaptation declines in older age. This has been attributed to cognitive impairments. One relevant cognitive function could be creativity, since creativity is implicated as mediator of early learning. The present study therefore evaluates whether two aspects of creativity, divergent and convergent thinking, are differentially involved in the age-dependent decline of visuomotor adaptation. In 25 young and 24 older volunteers, divergent thinking was assessed by the alternative-uses-task (AUT), convergent thinking by the Intelligenz-Struktur-Test-2000 (IST), and sensorimotor-adaptation by a pointing task with 60° rotated visual feedback. Young participants outperformed older participants in all three tasks. AUT scores were positively associated with young but not older participants' adaptive performance, whereas IST scores were negatively associated with older but not young participants' adaptive performance. This pattern of findings could be attributed to a consistent relationship between AUT, IST and adaptation; taking this into account, adaptation deficits of older participants were no longer significant. We conclude that divergent thinking supports workaround-strategies during adaptation, but doesn't influence visuomotor recalibration. Furthermore, the decay of divergent thinking in older adults may explain most of age-related decline of adaptive strategies. When the age-related decay of divergent thinking coincides with well-preserved convergent thinking, adaptation suffers most. Copyright © 2015 Elsevier B.V. All rights reserved.

Divergence in sex steroid hormone signaling between sympatric species of Japanese threespine stickleback.

Directory of Open Access Journals (Sweden)

Jun Kitano

Full Text Available Sex steroids mediate the expression of sexually dimorphic or sex-specific traits that are important both for mate choice within species and for behavioral isolation between species. We investigated divergence in sex steroid signaling between two sympatric species of threespine stickleback (Gasterosteus aculeatus: the Japan Sea form and the Pacific Ocean form. These sympatric forms diverge in both male display traits and female mate choice behaviors, which together contribute to asymmetric behavioral isolation in sympatry. Here, we found that plasma levels of testosterone and 17β-estradiol differed between spawning females of the two sympatric forms. Transcript levels of follicle-stimulating hormone-β (FSHβ gene were also higher in the pituitary gland of spawning Japan Sea females than in the pituitary gland of spawning Pacific Ocean females. By contrast, none of the sex steroids examined were significantly different between nesting males of the two forms. However, combining the plasma sex steroid data with testis transcriptome data suggested that the efficiency of the conversion of testosterone into 11-ketotestosterone has likely diverged between forms. Within forms, plasma testosterone levels in males were significantly correlated with male body size, a trait important for female mate choice in the two sympatric species. These results demonstrate that substantial divergence in sex steroid signaling can occur between incipient sympatric species. We suggest that investigation of the genetic and ecological mechanisms underlying divergence in hormonal signaling between incipient sympatric species will provide a better understanding of the mechanisms of speciation in animals.

Vector tomography for reconstructing electric fields with non-zero divergence in bounded domains

Science.gov (United States)

Koulouri, Alexandra; Brookes, Mike; Rimpiläinen, Ville

2017-01-01

In vector tomography (VT), the aim is to reconstruct an unknown multi-dimensional vector field using line integral data. In the case of a 2-dimensional VT, two types of line integral data are usually required. These data correspond to integration of the parallel and perpendicular projection of the vector field along the integration lines and are called the longitudinal and transverse measurements, respectively. In most cases, however, the transverse measurements cannot be physically acquired. Therefore, the VT methods are typically used to reconstruct divergence-free (or source-free) velocity and flow fields that can be reconstructed solely from the longitudinal measurements. In this paper, we show how vector fields with non-zero divergence in a bounded domain can also be reconstructed from the longitudinal measurements without the need of explicitly evaluating the transverse measurements. To the best of our knowledge, VT has not previously been used for this purpose. In particular, we study low-frequency, time-harmonic electric fields generated by dipole sources in convex bounded domains which arise, for example, in electroencephalography (EEG) source imaging. We explain in detail the theoretical background, the derivation of the electric field inverse problem and the numerical approximation of the line integrals. We show that fields with non-zero divergence can be reconstructed from the longitudinal measurements with the help of two sparsity constraints that are constructed from the transverse measurements and the vector Laplace operator. As a comparison to EEG source imaging, we note that VT does not require mathematical modeling of the sources. By numerical simulations, we show that the pattern of the electric field can be correctly estimated using VT and the location of the source activity can be determined accurately from the reconstructed magnitudes of the field.

Robust Covariance Estimators Based on Information Divergences and Riemannian Manifold

Directory of Open Access Journals (Sweden)

Xiaoqiang Hua

2018-03-01

Full Text Available This paper proposes a class of covariance estimators based on information divergences in heterogeneous environments. In particular, the problem of covariance estimation is reformulated on the Riemannian manifold of Hermitian positive-definite (HPD matrices. The means associated with information divergences are derived and used as the estimators. Without resorting to the complete knowledge of the probability distribution of the sample data, the geometry of the Riemannian manifold of HPD matrices is considered in mean estimators. Moreover, the robustness of mean estimators is analyzed using the influence function. Simulation results indicate the robustness and superiority of an adaptive normalized matched filter with our proposed estimators compared with the existing alternatives.

Ecological divergence and evolutionary transition of resprouting types in Banksia attenuata.

Science.gov (United States)

He, Tianhua

2014-08-01

Resprouting is a key functional trait that allows plants to survive diverse disturbances. The fitness benefits associated with resprouting include a rapid return to adult growth, early flowering, and setting seed. The resprouting responses observed following fire are varied, as are the ecological outcomes. Understanding the ecological divergence and evolutionary pathways of different resprouting types and how the environment and genetics interact to drive such morphological evolution represents an important, but under-studied, topic. In the present study, microsatellite markers and microevolutionary approaches were used to better understand: (1) whether genetic differentiation is related to morphological divergence among resprouting types and if so, whether there are any specific genetic variations associated with morphological divergence and (2) the evolutionary pathway of the transitions between two resprouting types in Banksia attenuata (epicormic resprouting from aerial stems or branch; resprouting from a underground lignotuber). The results revealed an association between population genetic differentiation and the morphological divergence of postfire resprouting types in B. attenuata. A microsatellite allele has been shown to be associated with epicormic populations. Approximate Bayesian Computation analysis revealed a likely evolutionary transition from epicormic to lignotuberous resprouting in B. attenuata. It is concluded that the postfire resprouting type in B. attenuata is likely determined by the fire's characteristics. The differentiated expression of postfire resprouting types in different environments is likely a consequence of local genetic adaptation. The capacity to shift the postfire resprouting type to adapt to diverse fire regimes is most likely the key factor explaining why B. attenuata is the most widespread member of the Banksia genus.

Plasmodium falciparum in the southeastern Atlantic forest: a challenge to the bromeliad-malaria paradigm?

Science.gov (United States)

Laporta, Gabriel Zorello; Burattini, Marcelo Nascimento; Levy, Debora; Fukuya, Linah Akemi; de Oliveira, Tatiane Marques Porangaba; Maselli, Luciana Morganti Ferreira; Conn, Jan Evelyn; Massad, Eduardo; Bydlowski, Sergio Paulo; Sallum, Maria Anice Mureb

2015-04-25

Recently an unexpectedly high prevalence of Plasmodium falciparum was found in asymptomatic blood donors living in the southeastern Brazilian Atlantic forest. The bromeliad-malaria paradigm assumes that transmission of Plasmodium vivax and Plasmodium malariae involves species of the subgenus Kerteszia of Anopheles and only a few cases of P. vivax malaria are reported annually in this region. The expectations of this paradigm are a low prevalence of P. vivax and a null prevalence of P. falciparum. Therefore, the aim of this study was to verify if P. falciparum is actively circulating in the southeastern Brazilian Atlantic forest remains. In this study, anophelines were collected with Shannon and CDC-light traps in seven distinct Atlantic forest landscapes over a 4-month period. Field-collected Anopheles mosquitoes were tested by real-time PCR assay in pools of ten, and then each mosquito from every positive pool, separately for P. falciparum and P. vivax. Genomic DNA of P. falciparum or P. vivax from positive anophelines was then amplified by traditional PCR for sequencing of the 18S ribosomal DNA to confirm Plasmodium species. Binomial probabilities were calculated to identify non-random results of the P. falciparum-infected anopheline findings. The overall proportion of anophelines naturally infected with P. falciparum was 4.4% (21/480) and only 0.8% (4/480) with P. vivax. All of the infected mosquitoes were found in intermixed natural and human-modified environments and most were Anopheles cruzii (22/25 = 88%, 18 P. falciparum plus 4 P. vivax). Plasmodium falciparum was confirmed by sequencing in 76% (16/21) of positive mosquitoes, whereas P. vivax was confirmed in only 25% (1/4). Binomial probabilities suggest that P. falciparum actively circulates throughout the region and that there may be a threshold of the forested over human-modified environment ratio upon which the proportion of P. falciparum-infected anophelines increases significantly. These results

Connecting Amazonian, Cerrado, and Atlantic Forest histories: Paraphyly, old divergences, and modern population dynamics in tyrant-manakins (Neopelma/Tyranneutes, Aves: Pipridae).

Science.gov (United States)

Capurucho, João Marcos Guimarães; Ashley, Mary V; Ribas, Camila C; Bates, John M

2018-06-11

Several biogeographic hypotheses have been proposed to explain connections between Amazonian and Atlantic forest biotas. These hypotheses are related to the timing of the connections and their geographic patterns. We performed a phylogeographic investigation of Tyrant-manakins (Aves: Pipridae, Neopelma/Tyranneutes) which include species inhabiting the Amazon and Atlantic forests, as well as gallery forests of the Cerrado. Using DNA sequence data, we determined phylogenetic relationships, temporal and geographic patterns of diversification, and recent intraspecific population genetic patterns, relative to the history of these biomes. We found Neopelma to be a paraphyletic genus, as N. chrysolophum is sister to Neopelma + Tyranneutes, with an estimated divergence of approximately 18 Myrs BP, within the oldest estimated divergence times of other Amazonian and Atlantic forest avian taxa. Subsequent divergences in the group occurred from Mid Miocene to Early Pliocene and involved mainly the Amazonian species, with an expansion into and subsequent speciation in the Cerrado gallery forests by N. pallescens. We found additional structure within N. chrysocephalum and N. sulphureiventer. Analysis of recent population dynamics in N. chrysocephalum, N. sulphureiventer, and N. pallescens revealed recent demographic fluctuations and restrictions to gene flow related to environmental changes since the last glacial cycle. No genetic structure was detected across the Amazon River in N. pallescens. The tyrant-manakins represent an old historical connection between the Amazon and Atlantic Forest. Copyright © 2018. Published by Elsevier Inc.

Sex-specific responses to vocal convergence and divergence of contact calls in orange-fronted conures (Aratinga canicularis)

DEFF Research Database (Denmark)

Balsby, Thorsten J S; Scarl, Judith C

2008-01-01

, the similarity between the contact calls of different individuals may either increase (converge) or decrease (diverge). We conducted a playback experiment on wild-caught captive birds in which we simulated convergent, divergent and no-change interaction series with male and female contact calls. OFCs responded...... differently to convergent and divergent series of contact calls, but only when we considered the sex of the test birds. Males called most in response to convergent series, whereas females demonstrated high calling rates in response to both convergent and divergent interactions. Both sexes responded most...... function. The stronger overall response to convergent series suggests that convergence of contact calls is an affiliative signal....

Divergence-based tests for model diagnostic

Czech Academy of Sciences Publication Activity Database

Hobza, Tomáš; Esteban, M. D.; Morales, D.; Marhuenda, Y.

2008-01-01

Roč. 78, č. 13 (2008), s. 1702-1710 ISSN 0167-7152 R&D Projects: GA MŠk 1M0572 Grant - others:Instituto Nacional de Estadistica (ES) MTM2006-05693 Institutional research plan: CEZ:AV0Z10750506 Keywords : goodness of fit * devergence statistics * GLM * model checking * bootstrap Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 0.445, year: 2008 http://library.utia.cas.cz/separaty/2008/SI/hobza-divergence-based%20tests%20for%20model%20diagnostic.pdf

Carnot efficiency at divergent power output

Science.gov (United States)

Polettini, Matteo; Esposito, Massimiliano

2017-05-01

The widely debated feasibility of thermodynamic machines achieving Carnot efficiency at finite power has been convincingly dismissed. Yet, the common wisdom that efficiency can only be optimal in the limit of infinitely slow processes overlooks the dual scenario of infinitely fast processes. We corroborate that efficient engines at divergent power output are not theoretically impossible, framing our claims within the theory of Stochastic Thermodynamics. We inspect the case of an electronic quantum dot coupled to three particle reservoirs to illustrate the physical rationale.

Stimulating Divergent Thinking in Junior High Career Education.

Science.gov (United States)

Ranke, Charlotte; Champoux, Ellen M.

1981-01-01

Describes a middle school career-oriented teaching unit with emphasis on teaching for divergent thinking. The unit provides hands-on opportunities for eighth-grade students to explore careers using the knowledge and skills developed in their home economics class. The careers are restaurant management, hospitality service, and interior design. (CT)

Thrust characteristics of a series of convergent-divergent exhaust nozzles at subsonic and supersonic flight speeds

Science.gov (United States)

Fradenburgh, Evan A; Gorton, Gerald C; Beke, Andrew

1954-01-01

An experimental investigation of a series of four convergent-divergent exhaust nozzles was conducted in the Lewis 8-by-6 foot supersonic wind tunnel at Mach numbers of 0.1, 0.6, 1.6, and 2.0 over a range of nozzle pressure ratios. The thrust characteristics of these nozzles were determined by a pressure-integration technique. From a thrust standpoint, a nozzle designed to give uniform parallel flow at the exit had no advantage over the simple geometric design with conical convergent and divergent sections. The rapid-divergent nozzles might be competitive with the more gradual-divergent nozzles since the relatively short length of these nozzles would be advantageous from a weight standpoint and might result in smaller thrust losses due to friction. The thrusts, with friction losses neglected, were predicted satisfactorily by one-dimensional theory for the nozzles with relatively gradual divergence. The thrusts of the rapid-divergent designs were several percentages below the theoretical values at the design pressure ratio or above, while at low pressure ratios there was a considerable effect of free-stream Mach number, with thrusts considerably above theoretical values at subsonic speeds and somewhat above theoretical values at supersonic speeds. This Mach numb effect appeared to be related to the variation of the model base pressure with free-stream Mach number.

Divergent Effects of Dendritic Cells on Pancreatitis

Science.gov (United States)

2015-09-01

role of dendritic cells in pancreatitis. Dendritic cells are professional antigen presenting cells which initiate innate and adaptive immune... Lymphoid -tissue-specific homing of bone- marrow-derived dendritic cells . Blood. 113:6638–6647. http://dx.doi .org/10.1182/blood-2009-02-204321 Dapito...Award Number: W81XWH-12-1-0313 TITLE: Divergent Effects of Dendritic Cells on Pancreatitis PRINCIPAL INVESTIGATOR: Dr. George Miller

Evanescent Effects Can Alter Ultraviolet Divergences in Quantum Gravity without Physical Consequences

CERN Document Server

Bern, Zvi; Chi, Huan-Hang; Davies, Scott; Dixon, Lance; Nohle, Josh

2015-01-01

Evanescent operators such as the Gauss-Bonnet term have vanishing perturbative matrix elements in exactly D=4 dimensions. Similarly, evanescent fields do not propagate in D=4; a three-form field is in this class, since it is dual to a cosmological-constant contribution. In this Letter, we show that evanescent operators and fields modify the leading ultraviolet divergence in pure gravity. To analyze the divergence, we compute the two-loop identical-helicity four-graviton amplitude and determine the coefficient of the associated (non-evanescent) R^3 counterterm studied long ago by Goroff and Sagnotti. We compare two pairs of theories that are dual in D=4: gravity coupled to nothing or to three-form matter, and gravity coupled to zero-form or to two-form matter. Duff and van Nieuwenhuizen showed that, curiously, the one-loop conformal anomaly --- the coefficient of the Gauss-Bonnet operator --- changes under p-form duality transformations. We concur, and also find that the leading R^3 divergence changes under du...

Extensive shared polymorphism at non-MHC immune genes in recently diverged North American prairie grouse

Science.gov (United States)

Minias, Piotr; Bateson, Zachary W.; Whittingham, Linda A.; Johnson, Jeff A.; Oyler-McCance, Sara J.; Dunn, Peter O.

2018-01-01

Gene polymorphisms shared between recently diverged species are thought to be widespread and most commonly reflect introgression from hybridization or retention of ancestral polymorphism through incomplete lineage sorting. Shared genetic diversity resulting from incomplete lineage sorting is usually maintained for a relatively short period of time, but under strong balancing selection it may persist for millions of years beyond species divergence (balanced trans-species polymorphism), as in the case of the major histocompatibility complex (MHC) genes. However, balancing selection is much less likely to act on non-MHC immune genes. The aim of this study was to investigate the patterns of shared polymorphism and selection at non-MHC immune genes in five grouse species from Centrocercus and Tympanuchus genera. For this purpose, we genotyped five non-MHC immune genes that do not interact directly with pathogens, but are involved in signaling and regulate immune cell growth. In contrast to previous studies with MHC, we found no evidence for balancing selection or balanced trans-species polymorphism among the non-MHC immune genes. No haplotypes were shared between genera and in most cases more similar allelic variants sorted by genus. Between species within genera, however, we found extensive shared polymorphism, which was most likely attributable to introgression or incomplete lineage sorting following recent divergence and large ancestral effective population size (i.e., weak genetic drift). Our study suggests that North American prairie grouse may have attained relatively low degree of reciprocal monophyly at nuclear loci and reinforces the rarity of balancing selection in non-MHC immune genes.

Temperature niche shift observed in a Lepidoptera population under allochronic divergence.

Science.gov (United States)

Santos, H; Paiva, M R; Tavares, C; Kerdelhué, C; Branco, M

2011-09-01

A process of adaptive divergence for tolerance to high temperatures was identified using a rare model system, consisting of two sympatric populations of a Lepidoptera (Thaumetopoea pityocampa) with different life cycle timings, a 'mutant' population with summer larval development, Leiria SP, and the founder natural population, having winter larval development, Leiria WP. A third, allopatric population (Bordeaux WP) was also studied. First and second instar larvae were experimentally exposed to daily-cycles of heat treatment reaching maximum values of 36, 38, 40 and 42 °C; control groups placed at 25 °C. A lethal temperature effect was only significant at 42 °C, for Leiria SP, whereas all temperatures tested had a significant negative effect upon Leiria WP, thus indicating an upper threshold of survival c.a. 6 °C above that of the WP. Cox regression model, for pooled heat treatments, predicted mortality hazard to increase for Leiria WP (+108%) and Bordeaux WP (+78%) in contrast to Leiria SP; to increase by 24% for each additional °C; and to decrease by 53% from first to second instar larvae. High variability among individuals was observed, a population characteristic that may favour selection and consequent adaptation. Present findings provide an example of ecological differentiation, following a process of allochronic divergence. Results further contribute to a better understanding of the implications of climate change for ecological genetics. © 2011 The Authors. Journal of Evolutionary Biology © 2011 European Society For Evolutionary Biology.

Ecological explanations to island gigantism: dietary niche divergence, predation, and size in an endemic lizard.

Science.gov (United States)

Runemark, Anna; Sagonas, Kostas; Svensson, Erik I

2015-08-01

Although rapid evolution of body size on islands has long been known, the ecological mechanisms behind this island phenomenon remain poorly understood. Diet is an important selective pressure for morphological divergence. Here we investigate if selection for novel diets has contributed to the multiple independent cases of island gigantism in the Skyros wall lizard (Podarcis gaigeae) and if diet, predation, or both factors best explain island gigantism. We combined data on body size, shape, bite force, and realized and available diets to address this. Several lines of evidence suggest that diet has contributed to the island gigantism. The larger islet lizards have relatively wider heads and higher bite performance in relation to mainland lizards than would be expected from size differences alone. The proportions of consumed and available hard prey are higher on islets than mainland localities, and lizard body size is significantly correlated with the proportion of hard prey. Furthermore, the main axis of divergence in head shape is significantly correlated with dietary divergence. Finally, a model with only diet and one including diet and predation regime explain body size divergence equally well. Our results suggest that diet is an important ecological factor behind insular body size divergence, but could be consistent with an additional role for predation.

Tuberlent heat transfer and friction in four-wall convergent/divergent square channels with one ribbed wall

Energy Technology Data Exchange (ETDEWEB)

Ahn, Soo Whan; Lee, Myung Sung [Dept. of Mechanical System Engineering, Institute of Marine Industry, Gyeongsang National University, Jinju (Korea, Republic of)

2015-10-15

The local heat transfer and pressure drop of developed turbulent flows in convergent/divergent channels with square axial cross-sectional areas were experimentally investigated to improve the channel design, such as a gas turbine cooling system. Square convergent/divergent channels with one ribbed wall were manufactured with a fixed rib height e of 10 mm and a ratio of rib spacing p to height e of 10. The measurement was conducted for Reynolds numbers from 15,000 to 89,000. Convergent, divergent, and straight channels with ratios D{sub ho}/D{sub hi} of 0.75, 1.33, and 1.0, respectively, are considered. Of the three channel types, the ribbed divergent channel was found to produce the best thermal performance under identical flow rate, pumping power, and pressure loss conditions.

Micropolar Fluids Using B-spline Divergence Conforming Spaces

KAUST Repository

Sarmiento, Adel; Garcia, Daniel; Dalcin, Lisandro; Collier, Nathan; Calo, Victor M.

2014-01-01

The divergence free formulation was used to guarantee an accurate solution of the flow. This formulation was implemented using the framework PetIGA as a basis, using its parallel stuctures to achieve high scalability. The results of the square heat driven cavity test case are in good agreement with those reported earlier.

Analysis of growth characteristics in short-term divergently selected ...

African Journals Online (AJOL)

weeks of age body weight in divergent lines of Japanese quail. Growth curves for both sexes within each selection group resembled the general sigmoid shape of a typical growth curve. Gompertz model curves and the observed growth curves were ...

Nonparametric Information Geometry: From Divergence Function to Referential-Representational Biduality on Statistical Manifolds

Directory of Open Access Journals (Sweden)

Jun Zhang

2013-12-01

Full Text Available Divergence functions are the non-symmetric “distance” on the manifold, Μθ, of parametric probability density functions over a measure space, (Χ,μ. Classical information geometry prescribes, on Μθ: (i a Riemannian metric given by the Fisher information; (ii a pair of dual connections (giving rise to the family of α-connections that preserve the metric under parallel transport by their joint actions; and (iii a family of divergence functions ( α-divergence defined on Μθ x Μθ, which induce the metric and the dual connections. Here, we construct an extension of this differential geometric structure from Μθ (that of parametric probability density functions to the manifold, Μ, of non-parametric functions on X, removing the positivity and normalization constraints. The generalized Fisher information and α-connections on M are induced by an α-parameterized family of divergence functions, reflecting the fundamental convex inequality associated with any smooth and strictly convex function. The infinite-dimensional manifold, M, has zero curvature for all these α-connections; hence, the generally non-zero curvature of M can be interpreted as arising from an embedding of Μθ into Μ. Furthermore, when a parametric model (after a monotonic scaling forms an affine submanifold, its natural and expectation parameters form biorthogonal coordinates, and such a submanifold is dually flat for α = ± 1, generalizing the results of Amari’s α-embedding. The present analysis illuminates two different types of duality in information geometry, one concerning the referential status of a point (measurable function expressed in the divergence function (“referential duality” and the other concerning its representation under an arbitrary monotone scaling (“representational duality”.

Adaptive divergence with gene flow in incipient speciation of Miscanthus floridulus / sinensis complex (Poaceae)

KAUST Repository

Huang, Chao-Li; Ho, Chuan-Wen; Chiang, Yu-Chung; Shigemoto, Yasumasa; Hsu, Tsai-Wen; Hwang, Chi-Chuan; Ge, Xue-Jun; Chen, Charles; Wu, Tai-Han; Chou, Chang-Hung; Huang, Hao-Jen; Gojobori, Takashi; Osada, Naoki; Chiang, Tzen-Yuh

2014-01-01

Young incipient species provide ideal materials for untangling the process of ecological speciation in the presence of gene flow. The Miscanthus floridulus/sinensis complex exhibits diverse phenotypic and ecological differences despite recent divergence (approximately 1.59million years ago). To elucidate the process of genetic differentiation during early stages of ecological speciation, we analyzed genomic divergence in the Miscanthus complex using 72 randomly selected genes from a newly assembled transcriptome. In this study, rampant gene flow was detected between species, estimated as M=3.36x10(-9) to 1.20x10(-6), resulting in contradicting phylogenies across loci. Nevertheless, beast analyses revealed the species identity and the effects of extrinsic cohesive forces that counteracted the non-stop introgression. As expected, early in speciation with gene flow, only 3-13 loci were highly diverged; two to five outliers (approximately 2.78-6.94% of the genome) were characterized by strong linkage disequilibrium, and asymmetrically distributed among ecotypes, indicating footprints of diversifying selection. In conclusion, ecological speciation of incipient species of Miscanthus probably followed the parapatric model, whereas allopatric speciation cannot be completely ruled out, especially between the geographically isolated northern and southern M.sinensis, for which no significant gene flow across oceanic barriers was detected. Divergence between local ecotypes in early-stage speciation began at a few genomic regions under the influence of natural selection and divergence hitchhiking that overcame gene flow.

Adaptive divergence with gene flow in incipient speciation of Miscanthus floridulus / sinensis complex (Poaceae)

KAUST Repository

Huang, Chao-Li

2014-11-11

Young incipient species provide ideal materials for untangling the process of ecological speciation in the presence of gene flow. The Miscanthus floridulus/sinensis complex exhibits diverse phenotypic and ecological differences despite recent divergence (approximately 1.59million years ago). To elucidate the process of genetic differentiation during early stages of ecological speciation, we analyzed genomic divergence in the Miscanthus complex using 72 randomly selected genes from a newly assembled transcriptome. In this study, rampant gene flow was detected between species, estimated as M=3.36x10(-9) to 1.20x10(-6), resulting in contradicting phylogenies across loci. Nevertheless, beast analyses revealed the species identity and the effects of extrinsic cohesive forces that counteracted the non-stop introgression. As expected, early in speciation with gene flow, only 3-13 loci were highly diverged; two to five outliers (approximately 2.78-6.94% of the genome) were characterized by strong linkage disequilibrium, and asymmetrically distributed among ecotypes, indicating footprints of diversifying selection. In conclusion, ecological speciation of incipient species of Miscanthus probably followed the parapatric model, whereas allopatric speciation cannot be completely ruled out, especially between the geographically isolated northern and southern M.sinensis, for which no significant gene flow across oceanic barriers was detected. Divergence between local ecotypes in early-stage speciation began at a few genomic regions under the influence of natural selection and divergence hitchhiking that overcame gene flow.

Positive selection and propeptide repeats promote rapid interspecific divergence of a gastropod sperm protein.

Science.gov (United States)

Hellberg, M E; Moy, G W; Vacquier, V D

2000-03-01

Male-specific proteins have increasingly been reported as targets of positive selection and are of special interest because of the role they may play in the evolution of reproductive isolation. We report the rapid interspecific divergence of cDNA encoding a major acrosomal protein of unknown function (TMAP) of sperm from five species of teguline gastropods. A mitochondrial DNA clock (calibrated by congeneric species divided by the Isthmus of Panama) estimates that these five species diverged 2-10 MYA. Inferred amino acid sequences reveal a propeptide that has diverged rapidly between species. The mature protein has diverged faster still due to high nonsynonymous substitution rates (> 25 nonsynonymous substitutions per site per 10(9) years). cDNA encoding the mature protein (89-100 residues) shows evidence of positive selection (Dn/Ds > 1) for 4 of 10 pairwise species comparisons. cDNA and predicted secondary-structure comparisons suggest that TMAP is neither orthologous nor paralogous to abalone lysin, and thus marks a second, phylogenetically independent, protein subject to strong positive selection in free-spawning marine gastropods. In addition, an internal repeat in one species (Tegula aureotincta) produces a duplicated cleavage site which results in two alternatively processed mature proteins differing by nine amino acid residues. Such alternative processing may provide a mechanism for introducing novel amino acid sequence variation at the amino-termini of proteins. Highly divergent TMAP N-termini from two other tegulines (Tegula regina and Norrisia norrisii) may have originated by such a mechanism.

NATO Technology: From Gap to Divergence? (Defense Horizons, July 2004)

National Research Council Canada - National Science Library

Daniel, Donald

2004-01-01

.... Over several decades, great disparities in the funding of defense research and technology by NATO members has produced a widening technological gap that threatens to become a divergence a condition...

The genomic distribution of intraspecific and interspecific sequence divergence of human segmental duplications relative to human/chimpanzee chromosomal rearrangements

Directory of Open Access Journals (Sweden)

Eichler Evan E

2008-08-01

Full Text Available Abstract Background It has been suggested that chromosomal rearrangements harbor the molecular footprint of the biological phenomena which they induce, in the form, for instance, of changes in the sequence divergence rates of linked genes. So far, all the studies of these potential associations have focused on the relationship between structural changes and the rates of evolution of single-copy DNA and have tried to exclude segmental duplications (SDs. This is paradoxical, since SDs are one of the primary forces driving the evolution of structure and function in our genomes and have been linked not only with novel genes acquiring new functions, but also with overall higher DNA sequence divergence and major chromosomal rearrangements. Results Here we take the opposite view and focus on SDs. We analyze several of the features of SDs, including the rates of intraspecific divergence between paralogous copies of human SDs and of interspecific divergence between human SDs and chimpanzee DNA. We study how divergence measures relate to chromosomal rearrangements, while considering other factors that affect evolutionary rates in single copy DNA. Conclusion We find that interspecific SD divergence behaves similarly to divergence of single-copy DNA. In contrast, old and recent paralogous copies of SDs do present different patterns of intraspecific divergence. Also, we show that some relatively recent SDs accumulate in regions that carry inversions in sister lineages.

Detection of novel divergent arenaviruses in boid snakes with inclusion body disease in The Netherlands.

Science.gov (United States)

Bodewes, R; Kik, M J L; Raj, V Stalin; Schapendonk, C M E; Haagmans, B L; Smits, S L; Osterhaus, A D M E

2013-06-01

Arenaviruses are bi-segmented negative-stranded RNA viruses, which were until recently only detected in rodents and humans. Now highly divergent arenaviruses have been identified in boid snakes with inclusion body disease (IBD). Here, we describe the identification of a new species and variants of the highly divergent arenaviruses, which were detected in tissues of captive boid snakes with IBD in The Netherlands by next-generation sequencing. Phylogenetic analysis of the complete sequence of the open reading frames of the four predicted proteins of one of the detected viruses revealed that this virus was most closely related to the recently identified Golden Gate virus, while considerable sequence differences were observed between the highly divergent arenaviruses detected in this study. These findings add to the recent identification of the highly divergent arenaviruses in boid snakes with IBD in the United States and indicate that these viruses also circulate among boid snakes in Europe.

Divergência genética entre acessos e cultivares de mamoneira por meio de estatística multivariada Genetic divergence on castor bean accesses and cultivars through multivariate analysis

Directory of Open Access Journals (Sweden)

Mauro Nóbrega da Costa

2006-11-01

Full Text Available O objetivo deste trabalho foi avaliar a divergência genética entre acessos e cultivares de mamoneira (Ricinus communis L. e utilizá-la como critério na escolha de genitores que viabilizem, a partir de hibridações, a formação de populações segregantes. Os tratamentos foram representados pelos acessos BRA 4871, BRA 2968, BRA 5550 e BRA 7722 Papo-de-gia, e as cultivares BRS 188 Paraguaçu, BRS 149 Nordestina, IAC-80, Mirante-10 e Pernambucana Melhorada. As características analisadas foram: início do florescimento (FR, número de racemos por planta (NRP, comprimento efetivo do racemo primário (CR, altura de planta (AP, potencial produtivo (PP e teor de óleo nas sementes (TO. A divergência genética foi estimada por meio de estatística multivariada, com base em variáveis canônicas e análise de agrupamento, tendo-se empregado a distância euclidiana média. Houve a formação de dois grupos: o grupo I formado por oito genótipos e o grupo II por apenas um genótipo, a cultivar Mirante-10. Apesar de a cultivar Mirante-10 ter sido a mais divergente, não deve ser recomendada para hibridação, por sua baixa média de desempenho. As demais cultivares também apresentam restrições para hibridação, por serem bastante similares. As variáveis que mais contribuíram para a divergência genética foram FR, AP, TO e CR.This work aimed to evaluate genetic divergence among castor bean (Ricinus communis L. cultivars, in order to enable the choice of parents which make the formation of segregating populations possible. Accesses BRA 4871, BRA 2968, BRA 5550 and BRA 7722 Papo-de-gia, and cultivars BRS 188 Paraguaçu, BRS 149 Nordestina, IAC-80, Mirante-10 and Pernambucana Melhorada were evaluated. Characteristics analyzed were: days to flowering, number of racemes per plant, length of pistillate region of main raceme, plant height, potential yield, and seed oil content. The genetic divergence among accesses and cultivars was studied by

Ultraviolet divergences of Einstein gravity

International Nuclear Information System (INIS)

Goroff, M.H.

1986-01-01

The author discuss a two-loop calculation showing that the S matrix of Einstein's theory of gravity contains nonrenormalizable ultraviolet divergences in four dimension. The author discusses the calculation in both background field and normal field theory. The author describes a new method for dealing with ghost fields in gauge theories by combining them with suitable extensions of the gauge fields in higher dimensions. The author shows how using subtracted integrals in the calculation of higher loop graphs simplifies the calculation in the background field method by eliminating the need for mixed counterterms. Finally, the author makes some remarks about the implications of the result for supergravity theories

Diverging expectations in buyer-seller relationships

DEFF Research Database (Denmark)

Andersen, Poul Houman; Christensen, Poul Rind; Damgaard, Torben

2009-01-01

Many firms assume that outsourcing partnerships may allow them to strengthen their overall competitiveness. Lured by its intuitive appeal, several enter into such partnerships, only to realize that they represent a marginal rather than a magical solution to their quest for increasing market...... SMEs. We discuss four relational expectations derived from the B2B literature on relational norms for addressing these divergences: Quality, frequency and scope of communication, role specifications and coordination of work nature of planning horizons, and trustworthiness and link these to relationship...

Diverging diamond interchange performance evaluation (I-44 and Route 13)

Science.gov (United States)

2011-02-01

Performance evaluation was conducted on the first diverging diamond interchange (DDI) or double : crossover interchange (DCD) constructed in the United States. This evaluation assessed traffic operations, safety and : public perceptions t...

Phosphorous Diffuser Diverged Blue Laser Diode for Indoor Lighting and Communication

KAUST Repository

Chi, Yu-Chieh

2015-12-21

An advanced light-fidelity (Li-Fi) system based on the blue Gallium nitride (GaN) laser diode (LD) with a compact white-light phosphorous diffuser is demonstrated for fusing the indoor white-lighting and visible light communication (VLC). The phosphorous diffuser adhered blue GaN LD broadens luminescent spectrum and diverges beam spot to provide ample functionality including the completeness of Li-Fi feature and the quality of white-lighting. The phosphorous diffuser diverged white-light spot covers a radiant angle up to 120o with CIE coordinates of (0.34, 0.37). On the other hand, the degradation on throughput frequency response of the blue LD is mainly attributed to the self-feedback caused by the reflection from the phosphor-air interface. It represents the current state-of-the-art performance on carrying 5.2-Gbit/s orthogonal frequency-division multiplexed 16-quadrature-amplitude modulation (16-QAM OFDM) data with a bit error rate (BER) of 3.1 × 10−3 over a 60-cm free-space link. This work aims to explore the plausibility of the phosphorous diffuser diverged blue GaN LD for future hybrid white-lighting and VLC systems.

Qualitative investigation into students' use of divergence and curl in electromagnetism

Science.gov (United States)

Bollen, Laurens; van Kampen, Paul; Baily, Charles; De Cock, Mieke

2016-12-01

Many students struggle with the use of mathematics in physics courses. Although typically well trained in rote mathematical calculation, they often lack the ability to apply their acquired skills to physical contexts. Such student difficulties are particularly apparent in undergraduate electrodynamics, which relies heavily on the use of vector calculus. To gain insight into student reasoning when solving problems involving divergence and curl, we conducted eight semistructured individual student interviews. During these interviews, students discussed the divergence and curl of electromagnetic fields using graphical representations, mathematical calculations, and the differential form of Maxwell's equations. We observed that while many students attempt to clarify the problem by making a sketch of the electromagnetic field, they struggle to interpret graphical representations of vector fields in terms of divergence and curl. In addition, some students confuse the characteristics of field line diagrams and field vector plots. By interpreting our results within the conceptual blending framework, we show how a lack of conceptual understanding of the vector operators and difficulties with graphical representations can account for an improper understanding of Maxwell's equations in differential form. Consequently, specific learning materials based on a multiple representation approach are required to clarify Maxwell's equations.

Chloroplast genome evolution in early diverged leptosporangiate ferns.

Science.gov (United States)

Kim, Hyoung Tae; Chung, Myong Gi; Kim, Ki-Joong

2014-05-01

In this study, the chloroplast (cp) genome sequences from three early diverged leptosporangiate ferns were completed and analyzed in order to understand the evolution of the genome of the fern lineages. The complete cp genome sequence of Osmunda cinnamomea (Osmundales) was 142,812 base pairs (bp). The cp genome structure was similar to that of eusporangiate ferns. The gene/intron losses that frequently occurred in the cp genome of leptosporangiate ferns were not found in the cp genome of O. cinnamomea. In addition, putative RNA editing sites in the cp genome were rare in O. cinnamomea, even though the sites were frequently predicted to be present in leptosporangiate ferns. The complete cp genome sequence of Diplopterygium glaucum (Gleicheniales) was 151,007 bp and has a 9.7 kb inversion between the trnL-CAA and trnVGCA genes when compared to O. cinnamomea. Several repeated sequences were detected around the inversion break points. The complete cp genome sequence of Lygodium japonicum (Schizaeales) was 157,142 bp and a deletion of the rpoC1 intron was detected. This intron loss was shared by all of the studied species of the genus Lygodium. The GC contents and the effective numbers of codons (ENCs) in ferns varied significantly when compared to seed plants. The ENC values of the early diverged leptosporangiate ferns showed intermediate levels between eusporangiate and core leptosporangiate ferns. However, our phylogenetic tree based on all of the cp gene sequences clearly indicated that the cp genome similarity between O. cinnamomea (Osmundales) and eusporangiate ferns are symplesiomorphies, rather than synapomorphies. Therefore, our data is in agreement with the view that Osmundales is a distinct early diverged lineage in the leptosporangiate ferns.

Evolution of cichlid vision via trans-regulatory divergence

Directory of Open Access Journals (Sweden)

O’Quin Kelly E

2012-12-01

Full Text Available Abstract Background Phenotypic evolution may occur through mutations that affect either the structure or expression of protein-coding genes. Although the evolution of color vision has historically been attributed to structural mutations within the opsin genes, recent research has shown that opsin regulatory mutations can also tune photoreceptor sensitivity and color vision. Visual sensitivity in African cichlid fishes varies as a result of the differential expression of seven opsin genes. We crossed cichlid species that express different opsin gene sets and scanned their genome for expression Quantitative Trait Loci (eQTL responsible for these differences. Our results shed light on the role that different structural, cis-, and trans-regulatory mutations play in the evolution of color vision. Results We identified 11 eQTL that contribute to the divergent expression of five opsin genes. On three linkage groups, several eQTL formed regulatory “hotspots” associated with the expression of multiple opsins. Importantly, however, the majority of the eQTL we identified (8/11 or 73% occur on linkage groups located trans to the opsin genes, suggesting that cichlid color vision has evolved primarily via trans-regulatory divergence. By modeling the impact of just two of these trans-regulatory eQTL, we show that opsin regulatory mutations can alter cichlid photoreceptor sensitivity and color vision at least as much as opsin structural mutations can. Conclusions Combined with previous work, we demonstrate that the evolution of cichlid color vision results from the interplay of structural, cis-, and especially trans-regulatory loci. Although there are numerous examples of structural and cis-regulatory mutations that contribute to phenotypic evolution, our results suggest that trans-regulatory mutations could contribute to phenotypic divergence more commonly than previously expected, especially in systems like color vision, where compensatory changes in the

Divergência genética entre linhagens de matrizes de corte por meio de análise de agrupamento Genetic divergence in meat-type hens using cluster analysis

Directory of Open Access Journals (Sweden)

Marcos Yamaki

2008-05-01

Full Text Available Este trabalho foi realizado com o objetivo de avaliar a divergência genética de três linhagens de matrizes de corte do Programa de Melhoramento Genético da UFV. Foram avaliados dados de 270 aves, 90 de cada linhagem, para estudo das características dias para o primeiro ovo (DPPO, taxa de postura da 22ª à 56ª semana (TP, peso médio individual na 32ª (PMI1, 40ª (PMI2, 48ª (PMI3, 56ª (PMI4 e 64ª semanas de idade (PMI5; e peso médio do ovo, obtido pela média da pesagem de três ovos na 32ª (PMO1, 40ª (PMO2, 48ª (PMO3, 56ª (PMO4 e 64ª semanas de idade (PMO5. Para avaliar a divergência, foram utilizados dois métodos: hierárquico do vizinho mais próximo e otimização de Tocher. Pelo método hierárquico do vizinho mais próximo, utilizando-se a distância de Mahalanobis ao quadrado (D² como medida de dissimilaridade, formou-se um único grupo. Pelo método de otimização de Tocher, foram formados dois grupos, comprovando que os dois métodos foram discordantes na avaliação da divergência genética de linhas de aves de corte. As características que apresentaram as contribuições relativas mais expressivas para a divergência foram, respectivamente, PMO1 (25,71%, DDPO (21,76%, PMI4 (17,65% e PMI2 (13,04%.Genetic divergence among three lineages of meat-type hens from the Genetic Breeding Program of the Universidade Federal de Viçosa was evaluated for the following traits: days at first egg (DPPO, egg production rate (TP from 22nd to 56th week, body weight on the 32nd (PMI1, on 40th (PMI2, at 48th (PMI3, at 56th (PMI4 and at the 64th week (PMI5, egg weight on the 32nd (PMO1, on 40th (PMO2, at 48th (PMO3, at 56th (PMO4 and at the 64th week (PMO5. Traits were measured on 270 hens (90 of each lineage and two different methods were used to evaluate genetic divergence. For the single linkage hierarchical method, using the squared Mahalanobis distance (D² as the dissimilarity measure, only one single group was formed. When

Estudo da divergência genética entre seis linhas de aves Legorne utilizando técnicas de análise multivariada Genetic divergence study among six Leghorn lines by multivariate analysis

Directory of Open Access Journals (Sweden)

A.V. Pires

2002-06-01

Full Text Available A divergência genética entre seis linhas de aves Legorne (L1, L2, L3, L4, L5 e L6, desenvolvidas pela UFV, foi avaliada utilizando análise de variáveis canônicas e o método de agrupamento de Tocher. Foram incluídas no estudo oito características: peso corporal na 40ª semana (PC40, na 48ª semana (PC48, na 56ª semana (PC56; peso do ovo na 40ª semana (PO40, na 44ª semana (PO44, na 52ª semana (PO52, na 60ª semana (PO60 e taxa de postura da 40ª a 62ª semana (TP. Foi observada diferença entre as linhas quanto às características estudadas. A linha L4 mostrou-se divergente das demais, apresentando a menor média canônica, e foi alocada em grupo distinto das outras pelo teste de Tocher. O desempenho das diferentes linhas foi também avaliado por meio da análise de variância multivariada, usando o teste do maior autovalor de Roy, e por meio do teste de Roy para comparações múltiplas. Verificou-se divergência genética entre as linhas da UFV, sendo PC40 a característica que mais contribuiu para a divergência.Genetic divergence among six Leghorn lines (L1, L2, L3, L4, L5 e L6, developed by Universidade Federal de Viçosa, Brazil, was evaluated using canonical variate analysis and grouping method of Tocher. Eight traits were used: body weight at 40 weeks, at 48 weeks, at 56 weeks; egg weight at 40 weeks, at 44 weeks, at 52 weeks, at 60 weeks and laying ratio from 40 to 62 weeks of age. Significant differences were observed among lines for the studied traits. The line L4 was divergent in comparison with the other ones, showed the smallest canonical mean and was allocated in a different group. The performance of different genetic groups was also evaluated by multivariate analysis of variance, using Roy test of the largest eigenvalue and the Roy principle for multiple comparisons. Genetic divergence among UFV's lines was observed and body weight at 40 weeks was the trait that more contributed for this divergence.

Interspecific genetic divergence in grey mullets from the Goa region

Digital Repository Service at National Institute of Oceanography (India)

Menezes, M.R.; Martins, M.; Naik, S.

Genetic divergence and phylogenetic relationships among Mugil cephalus, Liza subviridis and Valamugil cunnesius were investigated by examining the electrophoretic patterns of ten enzymes and sarcoplasmic proteins. Among the 19 loci detected, eight...

Conductive solar wind models in rapidly diverging flow geometries

International Nuclear Information System (INIS)

Holzer, T.E.; Leer, E.

1980-01-01

A detailed parameter study of conductive models of the solar wind has been carried out, extending the previous similar studies of Durney (1972) and Durney and Hundhausen (1974) by considering collisionless inhibition of thermal conduction, rapidly diverging flow geometries, and the structure of solutions for the entire n 0 -T 0 plane (n 0 and T 0 are the coronal base density and temperature). Primary emphasis is placed on understanding the complex effects of the physical processes operative in conductive solar wind models. There are five points of particular interest that have arisen from the study: (1) neither collisionless inhibition of thermal conduction nor rapidly diverging flow geometries can significantly increase the solar wind speed at 1 AU; (2) there exists a firm upper limit on the coronal base temperature consistent with observed values of the coronal base pressure and solar wind mass flux density; (3) the principal effect of rapidly diverging flow geometries is a decrease in the solar wind mass flux density at 1 AU and an increase in the mass flux density at the coronal base; (4) collisionless inhibition of thermal conduction can lead to a solar wind flow speed that either increases or decreases with increasing coronal base density (n 0 ) and temperature (T 0 , depending on the region of the n 0 -T 0 plane considered; (5) there is a region of the n 0 -T/sub o/ plane at high coronal base densities where low-speed, high-mass-flux, transonic solar wind flows exist: a region not previously considered

On the Critical Role of Divergent Selection in Evolvability

Directory of Open Access Journals (Sweden)

Joel Lehman

2016-08-01

Full Text Available An ambitious goal in evolutionary robotics is to evolve increasingly complex robotic behaviors with minimal human design effort. Reaching this goal requires evolutionary algorithms that can unlock from genetic encodings their latent potential for evolvability. One issue clouding this goal is conceptual confusion about evolvability, which often obscures the aspects of evolvability that are important or desirable. The danger from such confusion is that it may establish unrealistic goals for evolvability that prove unproductive in practice. An important issue separate from conceptual confusion is the common misalignment between selection and evolvability in evolutionary robotics. While more expressive encodings can represent higher-level adaptations (e.g. sexual reproduction or developmental systems that increase long-term evolutionary potential (i.e. evolvability, realizing such potential requires gradients of fitness and evolvability to align. In other words, selection is often a critical factor limiting increasing evolvability. Thus, drawing from a series of recent papers, this article seeks to both (1 clarify and focus the ways in which the term evolvability is used within artificial evolution, and (2 argue for the importance of one type of selection, i.e. divergent selection, for enabling evolvability. The main argument is that there is a fundamental connection between divergent selection and evolvability (on both the individual and population level that does not hold for typical goal-oriented selection. The conclusion is that selection pressure plays a critical role in realizing the potential for evolvability, and that divergent selection in particular provides a principled mechanism for encouraging evolvability in artificial evolution.

Rethinking conformity and imitation: divergence, convergence, and social understanding.

Science.gov (United States)

Hodges, Bert H

2014-01-01

Social and developmental psychologists have stressed the pervasiveness and strength of humans' tendencies to conform and to imitate, and social anthropologists have argued that these tendencies are crucial to the formation of cultures. Research from four domains is reviewed and elaborated to show that divergence is also pervasive and potent, and it is interwoven with convergence in a complex set of dynamics that is often unnoticed or minimized. First, classic research in social conformity is reinterpreted in terms of truth, trust, and social solidarity, revealing that dissent is its most salient feature. Second, recent studies of children's use of testimony to guide action reveal a surprisingly sophisticated balance of trust and prudence, and a concern for truth and charity. Third, new experiments indicate that people diverge from others even under conditions where conformity seems assured. Fourth, current studies of imitation provide strong evidence that children are both selective and faithful in who, what, and why they follow others. All of the evidence reviewed points toward children and adults as being engaged, embodied partners with others, motivated to learn and understand the world, others, and themselves in ways that go beyond goals and rules, prediction and control. Even young children act as if they are in a dialogical relationship with others and the world, rather than acting as if they are solo explorers or blind followers. Overall, the evidence supports the hypothesis that social understanding cannot be reduced to convergence or divergence, but includes ongoing activities that seek greater comprehensiveness and complexity in the ability to act and interact effectively, appropriately, and with integrity.

Quantum networks in divergence-free circuit QED

Science.gov (United States)

Parra-Rodriguez, A.; Rico, E.; Solano, E.; Egusquiza, I. L.

2018-04-01

Superconducting circuits are one of the leading quantum platforms for quantum technologies. With growing system complexity, it is of crucial importance to develop scalable circuit models that contain the minimum information required to predict the behaviour of the physical system. Based on microwave engineering methods, divergent and non-divergent Hamiltonian models in circuit quantum electrodynamics have been proposed to explain the dynamics of superconducting quantum networks coupled to infinite-dimensional systems, such as transmission lines and general impedance environments. Here, we study systematically common linear coupling configurations between networks and infinite-dimensional systems. The main result is that the simple Lagrangian models for these configurations present an intrinsic natural length that provides a natural ultraviolet cutoff. This length is due to the unavoidable dressing of the environment modes by the network. In this manner, the coupling parameters between their components correctly manifest their natural decoupling at high frequencies. Furthermore, we show the requirements to correctly separate infinite-dimensional coupled systems in local bases. We also compare our analytical results with other analytical and approximate methods available in the literature. Finally, we propose several applications of these general methods to analogue quantum simulation of multi-spin-boson models in non-perturbative coupling regimes.

Divergent synthesis and optoelectronic properties of oligodiacetylene building blocks

NARCIS (Netherlands)

Pilzak, G.S.; Lagen, van B.; Sudhölter, E.J.R.; Zuilhof, H.

2008-01-01

A new and divergent synthetic route to oligodiacetylene (ODA) building blocks has been developed via Sonogashira reactions under a reductive atmosphere. These central building blocks provide a new way for rapid preparation of long ODAs. In addition, we report on their optoelectronic properties which

Diverging patterns with endogenous labor migration.

Science.gov (United States)

Reichlin, P; Rustichini, A

1998-05-05

"The standard neoclassical model cannot explain persistent migration flows and lack of cross-country convergence when capital and labor are mobile. Here we present a model where both phenomena may take place.... Our model is based on the Arrow-Romer approach to endogenous growth theory. We single out the importance of a (however weak) scale effect from the size of the workforce.... The main conclusion of this simple model is that lack of convergence, or even divergence, among countries is possible, even with perfect capital mobility and labor mobility." excerpt

Late-time structure of the Bunch-Davies FRW wavefunction

Science.gov (United States)

Konstantinidis, George; Mahajan, Raghu; Shaghoulian, Edgar

2016-10-01

In this short note we organize a perturbation theory for the Bunch-Davies wavefunction in flat, accelerating cosmologies. The calculational technique avoids the in-in formalism and instead uses an analytic continuation from Euclidean signature. We will consider both massless and conformally coupled self-interacting scalars. These calculations explicitly illustrate two facts. The first is that IR divergences get sharper as the acceleration slows. The second is that UV-divergent contact terms in the Euclidean computation can contribute to the absolute value of the wavefunction in Lorentzian signature. Here UV divergent refers to terms involving inverse powers of the radial cutoff in the Euclidean computation. In Lorentzian signature such terms encode physical time dependence of the wavefunction.

Conserved quantities for stationary Einstein-Maxwell space-times

International Nuclear Information System (INIS)

Esposito, F.P.; Witten, L.

1978-01-01

It is shown that every stationary Einstein-Maxwell space-time has eight divergence-free vector fields and these are isolated in general form. The vector fields and associated conserved quantities are calculated for several families of space-times. (Auth.)

Patterns of divergence in the morphology of ceratopsian dinosaurs: sympatry is not a driver of ornament evolution.

Science.gov (United States)

Knapp, Andrew; Knell, Robert J; Farke, Andrew A; Loewen, Mark A; Hone, David W E

2018-03-28

Establishing the origin and function of unusual traits in fossil taxa provides a crucial tool in understanding macroevolutionary patterns over long periods of time. Ceratopsian dinosaurs are known for their exaggerated and often elaborate horns and frills, which vary considerably between species. Many explanations have been proposed for the origin and evolution of these 'ornamental' traits, from predator defence to socio-sexual dominance signalling and, more recently, species recognition. A key prediction of the species recognition hypothesis is that two or more species possessing divergent ornamental traits should have been at least partially sympatric. For the first time to our knowledge, we test this hypothesis in ceratopsians by conducting a comparison of the morphological characters of 46 species. A total of 350 ceratopsian cladistic characters were categorized as either 'internal', 'display' (i.e. ornamental) or 'non display'. Patterns of diversity of these characters were evaluated across 1035 unique species pairs. Display characters were found to diverge rapidly overall, but sympatric species were not found to differ significantly in their ornamental disparity from non-sympatric species, regardless of phylogenetic distance. The prediction of the species recognition hypothesis, and thus the idea that ornamentation evolved as a species recognition mechanism, has no statistical support among known ceratopsians. © 2018 The Authors.

Gray Matter Volume of the Lingual Gyrus Mediates the Relationship between Inhibition Function and Divergent Thinking