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Sample records for acutatum agente causal

  1. Molecular characterization and pathogenicity assays of Colletotrichum acutatum, causal agent for lime anthracnose in Texas

    Science.gov (United States)

    Several distorted Mexican lime [Citrus aurantiifolia (Christm). Swingle] fruit, leaf, and twig samples with lime anthracnose symptoms were collected from three trees in residential areas of Brownsville, Texas. The causal fungal organism, Colletotrichum acutatum J. H. Simmonds was isolated from leave...

  2. Efeito de extratos de plantas medicinais no controle de Colletotrichum acutatum, agente causal da flor preta do morangueiro Effect of plant extract on control of Colletotrichum acutatum the causal agent of the black spot of strawberry

    Directory of Open Access Journals (Sweden)

    Taís Ferreira Almeida

    2009-09-01

    Full Text Available A flor preta do morangueiro, causada por Colletotrichum acutatum, acarreta sérios problemas à cultura. Com o objetivo de verificar a utilização de extratos vegetais no controle da doença, testes "in vitro" foram realizados com 11 extratos vegetais hidroalcoólicos produzidos de plantas utilizadas na medicina popular. Os extratos foram preparados a partir de diferentes partes da planta, de acordo com a espécie, utilizando água e álcool no processo de extração por maceração. Foi verificada a influência dos extratos no crescimento micelial, esporulação e germinaç��o de esporos de C. acutatum, e também no controle do patógeno em folhas e frutos destacados. De acordo com a metodologia utilizada, os extratos vegetais que apresentaram maior eficiência foram os de folha e ramos de Ruta graveolens, Artemisia absinthium e bulbos de Allium sativum, indicando ter essas plantas potencial fungitóxico para o controle de C. acutatum.The black spot of strawberry plants caused by Colletotrichum acutatum, causes serious problems to the culture. To control the disease and minimize the use of fungicides, in vitro assays were accomplished with 11 different plant hydroalcoholic extract from plants species used in the popular medicine. The extracts were produced from plant parts (according to the species using water and alcohol in the extraction process for infusion. The influence of the extracts was verified in the micelial growth, esporulation and germination of the pathogen, besides a test with leaves and outstanding fruits. In agreement with the methodology used in this study, the extracts that showed the highest efficiency were the ones from Ruta graveolens, Artemisia absinthium and Allium sativum, which indicate such plants as potential fungitoxics for the control of C. acutatum.

  3. Whole genome sequence and genome annotation of Colletotrichum acutatum, causal agent of anthracnose in pepper plants in South Korea.

    Science.gov (United States)

    Han, Joon-Hee; Chon, Jae-Kyung; Ahn, Jong-Hwa; Choi, Ik-Young; Lee, Yong-Hwan; Kim, Kyoung Su

    2016-06-01

    Colletotrichum acutatum is a destructive fungal pathogen which causes anthracnose in a wide range of crops. Here we report the whole genome sequence and annotation of C. acutatum strain KC05, isolated from an infected pepper in Kangwon, South Korea. Genomic DNA from the KC05 strain was used for the whole genome sequencing using a PacBio sequencer and the MiSeq system. The KC05 genome was determined to be 52,190,760 bp in size with a G + C content of 51.73% in 27 scaffolds and to contain 13,559 genes with an average length of 1516 bp. Gene prediction and annotation were performed by incorporating RNA-Seq data. The genome sequence of the KC05 was deposited at DDBJ/ENA/GenBank under the accession number LUXP00000000.

  4. Saccharomyces cerevisiae: A novel and efficient biological control agent for Colletotrichum acutatum during pre-harvest.

    Science.gov (United States)

    Lopes, Marcos Roberto; Klein, Mariana Nadjara; Ferraz, Luriany Pompeo; da Silva, Aline Caroline; Kupper, Katia Cristina

    2015-06-01

    In this study, we evaluated the efficiency of six isolates of Saccharomyces cerevisiae in controlling Colletotrichum acutatum, the causal agent of postbloom fruit drop that occur in pre-harvest citrus. We analyzed the mechanisms of action involved in biological control such as: production of antifungal compounds, nutrient competition, detection of killer activity, and production of hydrolytic enzymes of the isolates of S. cerevisiae on C. acutatum and their efficiency in controlling postbloom fruit drop on detached citrus flowers. Our results showed that all six S. cerevisiae isolates produced antifungal compounds, competed for nutrients, inhibited pathogen germination, and produced killer activity and hydrolytic enzymes when in contact with the fungus wall. The isolates were able to control the disease when detached flowers were artificially inoculated, both preventively and curatively. In this work we identified a novel potential biological control agent for C. acutatum during pre-harvest. This is the first report of yeast efficiency for the biocontrol of postbloom fruit drop, which represents an important contribution to the field of biocontrol of diseases affecting citrus populations worldwide. Copyright © 2015 Elsevier GmbH. All rights reserved.

  5. Screening of antagonistic activity of microorganisms against Colletotrichum acutatum and Colletotrichum gloeosporioides

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    Živković Svetlana

    2010-01-01

    Full Text Available The antagonistic activities of five biocontrol agents: Trichoderma harzianum, Gliocladium roseum, Bacillus subtilis, Streptomyces noursei and Streptomyces natalensis, were tested in vitro against Colletotrichum acutatum and Colletotrichum gloeosporioides, the causal agents of anthracnose disease in fruit crops. The microbial antagonists inhibited mycelial growth in the dual culture assay and conidial germination of Colletotrichum isolates. The two Streptomyces species exhibited the strongest antagonism against isolates of C. acutatum and C. gloeosporioides. Microscopic examination showed that the most common mode of action was antibiosis. The results of this study identify T. harzianum, G. roseum, B. subtilis, S. natalensis and S. noursei as promising biological control agents for further testing against anthracnose disease in fruits. .

  6. [Antibibiotic resistance by nosocomial infections' causal agents].

    Science.gov (United States)

    Salazar-Holguín, Héctor Daniel; Cisneros-Robledo, María Elena

    2016-01-01

    The antibibiotic resistance by nosocomial infections (NI) causal agents constitutes a seriously global problematic that involves the Mexican Institute of Social Security's Regional General Hospital 1 in Chihuahua, Mexico; although with special features that required to be specified and evaluated, in order to concrete an effective therapy. Observational, descriptive and prospective study; by means of active vigilance all along 2014 in order to detect the nosocomial infections, for epidemiologic study, culture and antibiogram to identify its causal agents and antibiotics resistance and sensitivity. Among 13527 hospital discharges, 1079 displayed NI (8 %), standed out: the related on vascular lines, of surgical site, pneumonia and urinal track; they added up two thirds of the total. We carried out culture and antibiogram about 300 of them (27.8 %); identifying 31 bacterian species, mainly seven of those (77.9 %): Escherichia coli, Staphylococcus aureus and epidermidis, Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae and Enterobacter cloacae; showing multiresistance to 34 tested antibiotics, except in seven with low or without resistance at all: vancomycin, teicoplanin, linezolid, quinupristin-dalfopristin, piperacilin-tazobactam, amikacin and carbapenems. When we contrasted those results with the recommendations in the clinical practice guides, it aroused several contradictions; so they must be taken with reserves and has to be tested in each hospital, by means of cultures and antibiograms in practically every case of nosocomial infection.

  7. In vitro inhibition of pathogenic Verticillium dahliae , causal agent of ...

    African Journals Online (AJOL)

    In vitro inhibition of pathogenic Verticillium dahliae, causal agent of potato wilt disease in China by Trichoderma isolates. C Xiaojun, S Wongkaew, Y Jie, Y Xuehui, H Haiyong, W Shiping, T Qigqun, W Lishuang, D Athinuwat, N Buensanteai ...

  8. Phenotypic and molecular characterisation of the causal agent of ...

    African Journals Online (AJOL)

    A study was carried out to confirm the identity of the causal agent of anthracnose, a major fungal disease of mango in Ghana. Forty-five isolates of the pathogen were obtained from diseased mango plant parts, and were identified using morphological, physiological and molecular methods. The results showed that the ...

  9. Pathogenicity and fungicide sensitivity of the causal agent of ...

    African Journals Online (AJOL)

    Studies were carried out on the stem end rot disease of mango in Ghana. The incidence and severity of the disease were evaluated on mango fruits collected from major mango growing areas of Ghana. The causal agent was isolated on media and identified. The pathogenicity of the fungus and its cross-infection potential ...

  10. The biology of Colletotrichum acutatum

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    Diéguez-Uribeondo, Javier

    2004-06-01

    Full Text Available Colletotrichum acutatum is major pathogen of fruit crops, causing economically important losses of temperate, subtropical and tropical fruits worldwide. However, few studies have been carried out on key aspects of its biology. This is mainly because traditionally isolates of C. acutatum were often wrongly identified as C. gloeosporioides. Effective separation of the two species was not possible until the introduction of molecular tools for taxonomy. The life cycle of C. acutatum comprises a sexual and an asexual stage and much remains to be resolved regarding the genetics of sexuality and the effects of the sexual stage on population structure. Colletotrichum acutatum exhibits both infection strategies described for Colletotrichum species, i.e. intracellular hemibiotrophy and subcuticular-intramural necrotrophy, and may also undergo a period of quiescence in order to overcome resistance mechanisms in immature fruit such as pre-formed toxic compounds and phytoalexins, or due to the unsuitability of unripe fruit to fulfill the nutritional and energy requirements of the pathogen. Colletotrichum acutatum may overwinter as mycelium and/or appressoria in or on different parts of the host. Conidia are water-born and spread by rain episodes so infections are usually highest during the wettest periods of the growing season. Current management strategies for this fungus comprise the exploitation of cultivar resistance, cultural, chemical, and biological control methods, and preventive strategies such as disease-forecasting models. This review focuses on the current knowledge of biological aspects of C. acutatum and related Colletotrichum species and includes a discussion of the progress towards their control.Colletotrichum acutatum es uno de los principales hongos patógenos en agricultura y responsable de importantes pérdidas económicas en frutales en áreas tanto de climas templados como subtropicales y tropicales. Sin embargo, existen pocos estudios

  11. New Caledonian crows reason about hidden causal agents.

    Science.gov (United States)

    Taylor, Alex H; Miller, Rachael; Gray, Russell D

    2012-10-02

    The ability to make inferences about hidden causal mechanisms underpins scientific and religious thought. It also facilitates the understanding of social interactions and the production of sophisticated tool-using behaviors. However, although animals can reason about the outcomes of accidental interventions, only humans have been shown to make inferences about hidden causal mechanisms. Here, we show that tool-making New Caledonian crows react differently to an observable event when it is caused by a hidden causal agent. Eight crows watched two series of events in which a stick moved. In the first set of events, the crows observed a human enter a hide, a stick move, and the human then leave the hide. In the second, the stick moved without a human entering or exiting the hide. The crows inspected the hide and abandoned probing with a tool for food more often after the second, unexplained series of events. This difference shows that the crows can reason about a hidden causal agent. Comparative studies with the methodology outlined here could aid in elucidating the selective pressures that led to the evolution of this cognitive ability.

  12. The Colletotrichum acutatum species complex

    Science.gov (United States)

    Damm, U.; Cannon, P.F.; Woudenberg, J.H.C.; Crous, P.W.

    2012-01-01

    Colletotrichum acutatum is known as an important anthracnose pathogen of a wide range of host plants worldwide. Numerous studies have reported subgroups within the C. acutatum species complex. Multilocus molecular phylogenetic analysis (ITS, ACT, TUB2, CHS-1, GAPDH, HIS3) of 331 strains previously identified as C. acutatum and other related taxa, including strains from numerous hosts with wide geographic distributions, confirmed the molecular groups previously recognised and identified a series of novel taxa. Thirty-one species are accepted, of which 21 have not previously been recognised. Colletotrichum orchidophilum clusters basal to the C. acutatum species complex. There is a high phenotypic diversity within this complex, and some of the species appear to have preferences to specific hosts or geographical regions. Others appear to be plurivorous and are present in multiple regions. In this study, only C. salicis and C. rhombiforme formed sexual morphs in culture, although sexual morphs have been described from other taxa (especially as laboratory crosses), and there is evidence of hybridisation between different species. One species with similar morphology to C. acutatum but not belonging to this species complex was also described here as new, namely C. pseudoacutatum. Taxonomic novelties: New combinations - Colletotrichum limetticola (R.E. Clausen) Damm, P.F. Cannon & Crous, C. lupini (Bondar) Damm, P.F. Cannon & Crous, C. salicis (Fuckel) Damm, P.F. Cannon & Crous. New species - C. acerbum Damm, P.F. Cannon & Crous, C. australe Damm, P.F. Cannon & Crous, C. brisbanense Damm, P.F. Cannon & Crous, C. cosmi Damm, P.F. Cannon & Crous, C. costaricense Damm, P.F. Cannon & Crous, C. cuscutae Damm, P.F. Cannon & Crous, C. guajavae Damm, P.F. Cannon & Crous, C. indonesiense Damm, P.F. Cannon & Crous, C. johnstonii Damm, P.F. Cannon & Crous, C. kinghornii Damm, P.F. Cannon & Crous, C. laticiphilum Damm, P.F. Cannon & Crous, C. melonis Damm, P.F. Cannon & Crous, C

  13. SELECCIÓN Y REGENERACIÓN in vitro DE SOMACLONES DE TOMATE DE ÁRBOL (Solanum betacea cav. Sendt UTILIZANDO FILTRADOS DE CULTIVO DE Colletotrichum acutatum CON ACTIVIDAD PECTINASA SELECTION AND in vitro REGENERATION OF SOMACLONES OF TREE TOMATO (Solanum betacea cav. Sendt USING CULTURE FILTRATES OF Colletotrichum acutatum WITH PECTINASA ACTIVITY

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    Carlos Patiño Torres

    2007-12-01

    Full Text Available Se utilizaron filtrados de cultivo de Colletotrichum acutatum, agente causal de la antracnosis del tomate de árbol, para la selección in vitro de variantes somaclonales de ésta planta con resistencia potencial a la enfermedad. El filtrado, utilizado a varias concentraciones, demostró ser un agente de selección efectivo cuando se integró al medio de cultivo, pues causó niveles elevados de mortalidad de los explantes comparado con los tratamientos sin filtrado. Igualmente, se estudió el efecto de la benziladenina (BA ó BAP sobre la respuesta organogénica de explantes de tejido foliar de tomate de árbol.Culture filtrates of Colletotrichum acutatum, causal agent of the anthracnose disease in tree tomato, were used for the in vitro selection of somaclonal variants with potential resistance to this disease. Culture filtrates used at different concentrations, showed to be an effective agent of selection when they were mixed with the growth media. The findings indicated a high level of mortality for the explants growing on the ammended media as compared with these growing on non ammended one. The effect of the benziladenina (BA ó BAP on the organogenic response of leaf explants of tomato tree was also studied.

  14. Stenotrophomonas maltophilia: a new potential biocontrol agent of Ralstonia solanacearum, causal agent of potato brown rot

    NARCIS (Netherlands)

    Messiha, N.A.S.; Diepeningen, van A.D.; Farag, N.S.; Abdallah, S.A.; Janse, J.D.; Bruggen, van A.H.C.

    2007-01-01

    Stenotrophomonas maltophilia was isolated from the rhizosphere of eggplant in the Nile Delta of Egypt, and its antagonistic potential against Ralstonia solanacearum race 3 biovar 2, the causal agent of potato brown rot, was in vitro evaluated on KB agar medium and in vivo on potato plants. In vitro,

  15. Monilophthora roreri, causal agent of cacao frosty pod rot.

    Science.gov (United States)

    Bailey, Bryan A; Evans, Harry C; Phillips-Mora, Wilbert; Ali, Shahin S; Meinhardt, Lyndel W

    2017-12-01

    Taxonomy: Moniliophthora roreri (Cif.) H.C. Evans et al. (1978); Phylum Basidiomycota; Class Agaricomycetes; Order Agaricales; Family Marasmiaceae; Genus Moniliophthora. Biology: M. roreri attacks Theobroma and Herrania species causing frosty pod rot. Theobroma cacao (cacao) is the host of major economic concern. M. roreri is a hemibiotroph with a long biotrophic phase (45-90 days). Spore masses, of apparent asexual origin, are produced on the pod surface after initiation of the necrotrophic phase. Spores are spread by wind, rain and human activity. Symptoms of the biotrophic phase can include necrotic flecks and, in some cases, pod malformation, but pods otherwise remain asymptomatic. Relationship to Moniliophthora perniciosa. M. roreri and Moniliophthora perniciosa, causal agent of witches's broom disease of cacao, are closely related. Their genomes are similar, including many of the genes they carry considered important in the disease process. M. perniciosa, also a hemibiotroph, has a typical basidiomycete lifestyle and morphology, forming clamp connections and producing mushrooms. Basidiospores infect meristematic tissues including flower cushions, stem tips, and pods. M. roreri does not form clamp connections or mushrooms and infects pods only. Both pathogens are limited to the Western Hemisphere and are a threat to cacao production around the world. Agronomic importance: Disease losses due to frosty pod rot can reach 90% and result in field abandonment. M. roreri remains in the invasive phase in the Western Hemisphere not having reached Brazil, some islands within the Caribbean, and a few specific regions within otherwise invaded countries. The disease can be managed by a combination of cultural (for example maintaining tree height and removing infected pods) and chemical methods. These methods benefit from regional application but can be cost prohibitive. Breeding for disease resistance offers the greatest potential for frosty pod rot management and new

  16. Unveiling Members of Colletotrichum acutatum Species Complex Causing Colletotrichum Leaf Disease of Hevea brasiliensis in Sri Lanka.

    Science.gov (United States)

    Hunupolagama, D M; Chandrasekharan, N V; Wijesundera, W S S; Kathriarachchi, H S; Fernando, T H P S; Wijesundera, R L C

    2017-06-01

    Colletotrichum is an important fungal genus with great diversity, which causes anthracnose of a variety of crop plants including rubber trees. Colletotrichum acutatum and Colletotrichum gloeosporioides have been identified as the major causative agents of Colletotrichum leaf disease of rubber trees in Sri Lanka based on morphology, pathogenicity, and the analysis of internally transcribed spacer sequences of the nuclear ribosomal DNA. This study has been conducted to investigate the members of the C. acutatum species complex causing rubber leaf disease using a morphological and multi gene approach. For the first time in Sri Lanka, Colletotrichum simmondsii, Colletotrichum laticiphilum, Colletotrichum nymphaeae, and Colletotrichum citri have been identified as causative agents of Colletotrichum leaf disease in addition to C. acutatum s. str. Among them, C. simmondsii has been recognized as the major causative agent.

  17. Azospirillum brasilense siderophores with antifungal activity against Colletotrichum acutatum.

    Science.gov (United States)

    Tortora, María L; Díaz-Ricci, Juan C; Pedraza, Raúl O

    2011-04-01

    Anthracnose, caused by the fungus Colletotrichum acutatum is one of the most important diseases in strawberry crop. Due to environmental pollution and resistance produced by chemical fungicides, nowadays biological control is considered a good alternative for crop protection. Among biocontrol agents, there are plant growth-promoting bacteria, such as members of the genus Azospirillum. In this work, we demonstrate that under iron limiting conditions different strains of A. brasilense produce siderophores, exhibiting different yields and rates of production according to their origin. Chemical assays revealed that strains REC2 and REC3 secrete catechol type siderophores, including salicylic acid, detected by thin layer chromatography coupled with fluorescence spectroscopy and gas chromatography-mass spectrometry analysis. Siderophores produced by them showed in vitro antifungal activity against C. acutatum M11. Furthermore, this latter coincided with results obtained from phytopathological tests performed in planta, where a reduction of anthracnose symptoms on strawberry plants previously inoculated with A. brasilense was observed. These outcomes suggest that some strains of A. brasilense could act as biocontrol agent preventing anthracnose disease in strawberry.

  18. Isolation of Clostridium perfringens, Causal agents of necrotic enteritis in chickens

    OpenAIRE

    Miah, M. S.; Asaduzzaman, M.; Sufian, M. A.; Hossain, M. M.

    2011-01-01

    The present study was conducted to isolate the causal agent of necrotic enteritis (NE) from broiler chickens. A total of 50 jejunal samples from necropsied broiler chickens were collected for isolation of Clostridium perfringens, the causal agent of NE. The novel method for isolation of Clostridium perfringens was stab culture in association with pouring of olive oil on the surface of the stab culture. The collected samples in nutrient broth were kept in a candle jar and incubated for 24 hrs ...

  19. Antagonistic activity of fungi of Olea europaea L. against Colletotrichum acutatum.

    Science.gov (United States)

    Landum, Miguel C; Félix, Maria do Rosário; Alho, Joana; Garcia, Raquel; Cabrita, Maria João; Rei, Fernando; Varanda, Carla M R

    2016-02-01

    Fungi naturally present in olive trees were identified and tested for their antagonistic potential against Colletotrichum acutatum. A total of 14 isolates were identified, 12 belonged to genera Alternaria, Epicoccum, Fusarium, Aspergillus, Anthrinium, Chaetomium, Diaporthe, Nigrospora, one to family Xylariaceae and one was unclassified. All fungal isolates showed some inhibitory action over the growth of C. acutatum during dual culture growth, however, when agar-diffusible tests were performed only five fungal isolates caused C. acutatum growth inhibition: Alternaria sp. isolate 2 (26.8%), the fungus from Xylariaceae family (14.3%), Alternaria sp. isolate 1 (10.7%); Diaporthe sp. (10.7%), Nigrospora oryzae (3.5%). Volatile substances produced by these isolates were identified through gas-chromatography techniques, as phenylethyl alcohol, 4-methylquinazoline, benzothiazole, benzyl alcohol, lilial, galaxolide, among others. These inhibitory volatiles could play a significant role in reduction of C. acutatum expansion in olive and their study as potential biocontrol agents should be further explored. Copyright © 2015 Elsevier GmbH. All rights reserved.

  20. Canine Myiasis and Its Causal Agents in Northeastern Iran

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    Ali MOSHAVERINIA

    2016-03-01

    Full Text Available Background: Myiasis is defined as the infestation of live human and vertebrate animals with dipterous larvae for a certain period. There are reports indicating that dogs are the most common species affected by myiasis. This study was conducted to identify myiasis-causing flies in owned and stray dogs in Mashhad (Northeastern Iran. Methods: A total of 435 owned dogs and 800 stray dogs were examined for myia­sis. Myiasis cases were cured and fly larvae were identified by microscopy using the relevant standard identification keys.Results: Ten out of 435 owned dogs (2.29 % and 18 out of 800 stray dogs (2.25 % had myiasis. The causative agents of myiasis in dogs based on their fre­quencies were as follows: Wohlfahrtia magnifica (50%, Lucilia sericata (28.57% and Chrysomya albiceps (21.42%.Conclusion: W. magnifica was the most important myiasis-causing fly among the dogs sampled here, sometimes causing very serious damages. However, when treatment was given early enough, the larvae removed and the wound disinfected, the animals usually made a full recovery.

  1. In vitro evidence for sexual reproduction in Venturia effusa, causal agent of pecan scab

    Science.gov (United States)

    Venturia effusa is the causal agent of pecan scab, the most prevalent disease of pecan in the southeastern US. Venturia effusa is currently only known to reproduce asexually, yet the genetic diversity among populations of pecan scab suggest it is a sexually reproducing pathogen. Analysis of the mati...

  2. Structure elucidation and stereoselective total synthesis of pavettamine, the causal agent of gousiekte

    CSIR Research Space (South Africa)

    Bode, ML

    2010-03-01

    Full Text Available The structure elucidation of a novel natural product pavettamine (1), the causal agent of the plant toxicosis gousiekte, is reported. The structure was defined by analysis of NMR and MS data and the relative configuration followed from the 13C NMR...

  3. Draft Genome Sequence of Cercospora arachidicola, Causal Agent of Early Leaf Spot in Peanuts.

    Science.gov (United States)

    Orner, Valerie A; Cantonwine, Emily G; Wang, Xinye Monica; Abouelleil, Amr; Bochicchio, James; Nusbaum, Chad; Culbreath, Albert K; Abdo, Zaid; Arias, Renee S

    2015-11-05

    Cercospora arachidicola, causal agent of early leaf spot, is an economically important peanut pathogen. Lack of genetic information about this fungus prevents understanding the role that potentially diverse genotypes may have in peanut breeding programs. Here, we report for the first time a draft genome sequence of C. arachidicola. Copyright © 2015 Orner et al.

  4. Antagonistic activity Trichoderma harzianum Rifai on the causal agent of rice blast (Pyricularia grisea Sacc.

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    Ernesto Juniors Pérez Torres

    2017-10-01

    Full Text Available With the objective to evaluate the antagonistic activity of T. harzianum (strain A-34 on the causal agent of rice blast (P. grisea, were developed several in vitro experiments. It was evaluated the biocontrol mechanisms such as competition through mounted the percent inhibition of radial growth of hyphae of P. grisea from 24 to 240 hours and the antagonistic capacity. In addition, was evaluated micoparasitism to inclination the observation of events Microscopy winding, penetration, vacuolization, lysis, and antibiosis by observing 24 hours a confrontation between the hyphae of the phytopathogenic fungus and biological control agent. It was obtained at 120 hours 100 % inhibition of micelial growth of causal agent, what corresponded with the degree 1 of antagonistic capacity (scale and is recorded as a hyperparasitic action on P. grisea. It was evidenced an antibiotic effect of metabolites produced by T. harzianum (strain A-34 to 24 hours of confrontation, where there was time interaction between the hyphae of microorganisms with 14,3 % inhibition, also was evidence the micoparasitism events by penetration, vacuolization and lysis in the cells of phytopathogenic fungus. These results demonstrated the ability of T. harzianum (strain A-34 on causal agent of rice blast (P. grisea.

  5. Occupational Asthma: New Low-Molecular-Weight Causal Agents, 2000–2010

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    J. A. Pralong

    2012-01-01

    Full Text Available Background. More than 400 agents have been documented as causing occupational asthma (OA. The list of low-molecular-weight (LMW agents that have been identified as potential causes of OA is constantly expanding, emphasizing the need to continually update our knowledge by reviewing the literature. Objective. The objective of this paper was to identify all new LMW agents causing occupational asthma reported during the period 2000–2010. Methods. A Medline search was performed using the keywords occupational asthma, new allergens, new causes, and low-molecular-weight agents. Results. We found 39 publications describing 41 new LMW causal agents, which belonged to the following categories: drugs (n=12, wood dust (n=11, chemicals (n=8, metals (n=4, biocides (n=3, and miscellaneous (n=3. The diagnosis of OA was confirmed through SIC for 35 of 41 agents, peak expiratory flow monitoring for three (3 agents, and the clinical history alone for three (3 agents. Immunological tests provided evidence supporting an IgE-mediated mechanism for eight (8 (20% of the newly described agents. Conclusion. This paper highlights the importance of being alert to the occurrence of new LMW sensitizers, which can elicit OA. The immunological mechanism is explained by a type I hypersensitivity reaction in 20% of all newly described LMW agents.

  6. Cristulariella depraedans as causal agent of leaf spots of maple and other trees and shrubs

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    Tomasz Kowalski

    2013-12-01

    Full Text Available Results of the first studies in Poland on Cristulariella depraedans, the causal agent of necroses on tree and shrub leaves, are presented. The fungus was recorded on Acer platanoides, A. pseudoplatanus and eight other species of trees and shrubs, including Corylus avellana, Fagus sylvatica, Lonicera xylosteum and Padus avium that were not previously known as hosts of the fungus. The disease symptoms, which depend on the host plant species, the size and number of necrotic lesions on leaves, and the morphological features of the fungal propagules were characterized.

  7. Molecular Detection of Monilinia fructigena as Causal Agent of Brown Rot on Quince

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    Jovana Hrustić

    2012-01-01

    Full Text Available Species of the genus Monilinia are important causal agents of fruit rot on pome and stone fruits in Serbia. The pathogen is very harmful, especially on small properties and cottage plantations where intensive control measures are not applied. Quince is importanthost for the pathogens of this genus. During spring 2010, intensive occurrence of mummified fruits overwintering on branches of the quince was observed. The pathogen was isolated using standard phytopathological methods. Pathogenicity of eight obtained isolates was tested by artificial inoculation of injured apple fruits. Identification was performed according to pathogenic, morphological and ecological properties, and was confirmed by Multiplex polimeraze chain reaction, PCR. All the isolates studied caused brown rot on inoculated apple fruits. The isolates form light yellow colonies with lobate margins,with single-celled, transparent, elliptical or oval conidia in chains, regardless temperature or light presence. Sclerotia are observed in 14 days old cultures. The highest growth rate of most of the isolates is at 27°C and in dark. Based on studied pathogenic, morphological and ecological characteristics, it was found that the Monilinia fructigena is causal agent of brown rot of quince. Using specific primers (MO368-5, MO368-8R, MO368-10R, Laxa-R2for detection of Monilinia species in Multiplex PCR reaction, the expected fragment 402 bp in size was amplified, which confirmed that the studied isolates belonged to the speciesM. fructigena.

  8. Partial Activation of SA- and JA-Defensive Pathways in Strawberry upon Colletotrichum acutatum Interaction

    Science.gov (United States)

    Amil-Ruiz, Francisco; Garrido-Gala, José; Gadea, José; Blanco-Portales, Rosario; Muñoz-Mérida, Antonio; Trelles, Oswaldo; de los Santos, Berta; Arroyo, Francisco T.; Aguado-Puig, Ana; Romero, Fernando; Mercado, José-Ángel; Pliego-Alfaro, Fernando; Muñoz-Blanco, Juan; Caballero, José L.

    2016-01-01

    Understanding the nature of pathogen host interaction may help improve strawberry (Fragaria × ananassa) cultivars. Plant resistance to pathogenic agents usually operates through a complex network of defense mechanisms mediated by a diverse array of signaling molecules. In strawberry, resistance to a variety of pathogens has been reported to be mostly polygenic and quantitatively inherited, making it difficult to associate molecular markers with disease resistance genes. Colletotrichum acutatum spp. is a major strawberry pathogen, and completely resistant cultivars have not been reported. Moreover, strawberry defense network components and mechanisms remain largely unknown and poorly understood. Assessment of the strawberry response to C. acutatum included a global transcript analysis, and acidic hormones SA and JA measurements were analyzed after challenge with the pathogen. Induction of transcripts corresponding to the SA and JA signaling pathways and key genes controlling major steps within these defense pathways was detected. Accordingly, SA and JA accumulated in strawberry after infection. Contrastingly, induction of several important SA, JA, and oxidative stress-responsive defense genes, including FaPR1-1, FaLOX2, FaJAR1, FaPDF1, and FaGST1, was not detected, which suggests that specific branches in these defense pathways (those leading to FaPR1-2, FaPR2-1, FaPR2-2, FaAOS, FaPR5, and FaPR10) were activated. Our results reveal that specific aspects in SA and JA dependent signaling pathways are activated in strawberry upon interaction with C. acutatum. Certain described defense-associated transcripts related to these two known signaling pathways do not increase in abundance following infection. This finding suggests new insight into a specific putative molecular strategy for defense against this pathogen. PMID:27471515

  9. Characteristics of winter wheat varieties for resistance to causal agents and pests

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    Г. М. Ковалишина

    2016-02-01

    Full Text Available Purpose. Studying and identifying winter wheat varieties that are resistant to causal agents of major diseases and pests. Methods. Laboratory analysis, field study. Results. On artificial infection backgrounds of causal agents such varieties as ‘Smuhlianka’, ‘Svitanok Myronivskyi’, ‘Berehynia Myronіvska’, ‘Horlytsia Myronіvska’ have shown high level of resistance to brown rust; ‘Svitanok Myronivskyi’, ‘Berehynia Myronіvska’ – to powdery mildew; ‘Smuhlianka’ – to covered smut. Varieties ‘Voloshkova’, ‘Yuviliar Myronivskyi’, ‘Myrliena’, ‘Oberih Myronivskyi’, ‘Kolos Myronivschyny’, ‘Lehenda Myronivska’ had medium resistance to Septoria leaf blotch; ‘Smuhlianka’, ‘Myrliena’, ‘Oberih Myronivskyi’, ‘Berehynia Myronіvska’, ‘Horlytsia Myronіvska’, ‘Myronivska storichna’ – to Fusarium head blight; ‘Myronіvska 65’, ‘Smuhlianka’, ‘Lehenda Myronivska’, ‘Berehynia Myronіvska’ – to root rots. Among the varieties studied, there were those with group resistance to diseases: ‘Voloshkova’, ‘Myrliena’, ‘Yuviliar Myronivskyi’, ‘Oberih Myronivskyi’, ‘Bohdana’, ‘Myronivska storichna’, ‘Ekonomka’, ‘Svitanok Myronivskyi’, ‘Berehynia Myronіvska’, ‘Horlytsia Myronіvska’, ‘Smuhlianka’. Varieties bred at the V. M. Remeslo Myronivka Institute of Wheat are distinguished by pest resistance. During autumn tillering phase of winter wheat the smallest number of large cereal aphids was observed in varieties ‘Smuhlianka’ and ‘Myronivska storichna’, leafhoppers – in varieties ‘Smuhlianka’, ‘Myrliena’, ‘Yuviliar Myronivskyi’. The slight population of thrips in the phase of earing was marked in the variety ‘Kolos Myronivschyny’, in the milk-ripe stage the smallest number of larvae per ear was detected in varieties ‘Smuhlianka’, ‘Voloshkova’, ‘Kolos Myronivschyny’. Varieties

  10. Agents and Patients in Physical Settings: Linguistic Cues Affect the Assignment of Causality in German and Tongan

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    Andrea Bender

    2017-07-01

    Full Text Available Linguistic cues may be considered a potent tool for focusing attention on causes or effects. In this paper, we explore how different cues affect causal assignments in German and Tongan. From a larger screening study, two parts are reported here: Part 1 dealt with syntactic variations, including word order (agent vs. patient in first/subject position and case marking (e.g., as ergative vs. non-ergative in Tongan depending on verb type (transitive vs. intransitive. For two physical settings (wood floating on water and a man breaking a glass, participants assigned causality to the two entities involved. In the floating setting, speakers of the two languages were sensitive to syntactic variations, but differed in the entity regarded as causative. In the breaking setting, the human agent was uniformly regarded as causative. Part 2 dealt with implicit verb causality. Participants assigned causality to subject or object of 16 verbs presented in minimal social scenarios. In German, all verbs showed a subject (agent focus; in Tongan, the focus depended on the verb; and for nine verbs, the focus differed across languages. In conclusion, we discuss the question of domain-specificity of causal cognition, the role of the ergative as causal marker, and more general differences between languages.

  11. Agents and Patients in Physical Settings: Linguistic Cues Affect the Assignment of Causality in German and Tongan.

    Science.gov (United States)

    Bender, Andrea; Beller, Sieghard

    2017-01-01

    Linguistic cues may be considered a potent tool for focusing attention on causes or effects. In this paper, we explore how different cues affect causal assignments in German and Tongan. From a larger screening study, two parts are reported here: Part 1 dealt with syntactic variations, including word order (agent vs. patient in first/subject position) and case marking (e.g., as ergative vs. non-ergative in Tongan) depending on verb type (transitive vs. intransitive). For two physical settings (wood floating on water and a man breaking a glass), participants assigned causality to the two entities involved. In the floating setting, speakers of the two languages were sensitive to syntactic variations, but differed in the entity regarded as causative. In the breaking setting, the human agent was uniformly regarded as causative. Part 2 dealt with implicit verb causality. Participants assigned causality to subject or object of 16 verbs presented in minimal social scenarios. In German, all verbs showed a subject (agent) focus; in Tongan, the focus depended on the verb; and for nine verbs, the focus differed across languages. In conclusion, we discuss the question of domain-specificity of causal cognition, the role of the ergative as causal marker, and more general differences between languages.

  12. ‘Candidatus Liberibacter asiaticus’, Causal Agent of Citrus Huanglongbing, Is Reduced by Treatment with Brassinosteroids

    Science.gov (United States)

    Hernández, Ingrid; Portieles, Roxana; Rodríguez García, Mayra; López, Yunior; Aranguren, Miguel; Alonso, Eugenio; Delgado, Roger; Luis, Maritza; Batista, Lochy; Paredes, Camilo; Rodríguez, Meilyn; Pujol, Merardo; Ochagavia, María Elena; Falcón, Viviana; Terauchi, Ryohei; Matsumura, Hideo; Ayra-Pardo, Camilo; Llauger, Raixa; Pérez, María del Carmen; Núñez, Mirian; Borrusch, Melissa S.; Walton, Jonathan D.; Silva, Yussuan; Pimentel, Eulogio; Borroto, Carlos; Borrás-Hidalgo, Orlando

    2016-01-01

    Huanglongbing (HLB) constitutes the most destructive disease of citrus worldwide, yet no established efficient management measures exist for it. Brassinosteroids, a family of plant steroidal compounds, are essential for plant growth, development and stress tolerance. As a possible control strategy for HLB, epibrassinolide was applied to as a foliar spray to citrus plants infected with the causal agent of HLB, ‘Candidatus Liberibacter asiaticus’. The bacterial titers were reduced after treatment with epibrassinolide under both greenhouse and field conditions but were stronger in the greenhouse. Known defense genes were induced in leaves by epibrassinolide. With the SuperSAGE technology combined with next generation sequencing, induction of genes known to be associated with defense response to bacteria and hormone transduction pathways were identified. The results demonstrate that epibrassinolide may provide a useful tool for the management of HLB. PMID:26731660

  13. Microsatellite isolation and characterization for Colletotrichum spp, causal agent of anthracnose in Andean blackberry.

    Science.gov (United States)

    Marulanda, M L; López, A M; Isaza, L; López, P

    2014-09-26

    The genus Colletotrichum, comprised of pathogenic fungi that affect plants grown worldwide, causes the disease known as anthracnose in several fruit and vegetable species. Several studies conducted on plants have shown that the disease is characterized by the presence of one or several species of the fungus attacking the fruit or other organs of the same host. To develop and implement effective control strategies, it is vital to understand the genetic structure of the fungus in agricultural systems, identify associated Colletotrichum species, and define the subpopulations responsible for the disease. Molecular tools were accordingly developed to characterize genotypic populations of Colletotrichum spp, causal agent of anthracnose in commercial crops of Andean blackberry (Rubus glaucus Benth.). A microsatellite-enriched library for Colletotrichum gloeosporioides was developed to identify and characterize microsatellite loci among isolates collected in R. glaucus plantations. Thirty microsatellites were developed and tested in 36 isolates gathered from eight different blackberry-production areas of Colombia. Ten pairs of microsatellites were polymorphic.

  14. 'Candidatus Liberibacter asiaticus', Causal Agent of Citrus Huanglongbing, Is Reduced by Treatment with Brassinosteroids.

    Directory of Open Access Journals (Sweden)

    Eduardo Canales

    Full Text Available Huanglongbing (HLB constitutes the most destructive disease of citrus worldwide, yet no established efficient management measures exist for it. Brassinosteroids, a family of plant steroidal compounds, are essential for plant growth, development and stress tolerance. As a possible control strategy for HLB, epibrassinolide was applied to as a foliar spray to citrus plants infected with the causal agent of HLB, 'Candidatus Liberibacter asiaticus'. The bacterial titers were reduced after treatment with epibrassinolide under both greenhouse and field conditions but were stronger in the greenhouse. Known defense genes were induced in leaves by epibrassinolide. With the SuperSAGE technology combined with next generation sequencing, induction of genes known to be associated with defense response to bacteria and hormone transduction pathways were identified. The results demonstrate that epibrassinolide may provide a useful tool for the management of HLB.

  15. Identification and Control of Cladobotryum spp., Causal Agents of Cobeweb Disease of Cultivated Mushroom

    Directory of Open Access Journals (Sweden)

    Ivana Potočnik

    2009-01-01

    Full Text Available Cladobotryum spp. are causal agents of cobweb disease, one of the most serious diseases of cultivated mushroom (Agaricus bisporus (Lange Imbach in Serbia and worldwide, which affects product quality and yield. The disease symptoms are: cottony fluffy white oryellowish to pink colonies on mushroom casing, rapid colonization of casing surface, covering of host basidiomata by mycelia, and their decay. Prochloraz-Mn has been officially recommended for mushroom cultivation in EU countries. However, inefficiency of prochloraz-Mn has been noted at a level of spotting symptoms of cobweb disease. With regard to cases of resistance evolution and a general threat to the environment and human health, special attention should be focused on good programmes of hygiene, and inventing and developing alternative methods of disease control.

  16. Integrated Management of Causal Agents of Postharvest Fruit Rot of Apple

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    Mila Grahovac

    2011-01-01

    Full Text Available One of the major causes of poor quality and fruit loss (during storage and transportare diseases caused by phytopathogenic fungi. Economic losses which are the consequenceof the phytopathogenic fungus activity after harvest exceed the losses in the field.Themost important postharvest fungal pathogens of apple fruits are: Botrytis cinerea Pers. exFr., Penicillium expansum (Lk. Thom., Cryptosporiopsis curvispora (Peck. Grem., Colletotrichumgloeosporioides (Penz. Sacc., Monilinia sp., Gloeosporium album Osterw, Alternaria alternata(Fr. Keissler, Cladosporium herbarium Link., Cylindrocarpon mali (Alles. Wollenw., Stemphyliumbotryosum Wallr. The use of available protection technologies can significantly reducelosses caused by pathogens in storage. The concept of integrated pest management (IPMin apple fruits i.e. sustainable approach in control of causal agents of postharvest fruit rot,using cultural, physical, biological and chemical measures, to minimize economic, healthand risks to consumers and environment, is presented in the paper.

  17. Molecular identification of pathogenic Fusarium species, the causal agents of tomato wilt in western Iran

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    Chehri Khosrow

    2016-04-01

    Full Text Available Fusarium species are causal agents of fungal diseases occurring frequently in numerous agriculturally important plants, including potato, garlic and are one of the common pathogens of tomato, causing root rot in the west part of Iran. Therefore, the objectives of this study were to isolate and identify disease-causing Fusarium species from infected tomatoes based on the morphological and molecular characteristics. Twenty-five isolates of Fusarium were obtained from infected root of tomato plants collected from the fields in different regions of western Iran. Based on morphological features, the strains were classified into four following Fusarium species: F. oxysporum, F. redolens, F. proliferatum and F. verticillioides. The phylogenetic trees based on tef1 and tub2 dataset clearly distinguished closely related species. All of the isolates were evaluated for their pathogenicity on healthy tomato seedlings in the greenhouse. This is the first report on molecular identification of Fusarium species isolated from tomato plants cultivated in Iran.

  18. El consumo de basuco* como agente causal de alteraciones en la encía

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    Lorena Dávila

    2001-08-01

    Full Text Available El abuso en el consumo de drogas, entre ellas al BASUCO, es uno de los grandes problemas de salud pública que tiene que afrontar nuestra comunidad. En este estudio se utilizaron 40 ratas de la cepa Wistar, 20 con carácter experimental y 20 de control utilizando agua destilada durante 16 semanas. Se demostró que existe una relación directa entre el uso de BASUCO y las alteraciones clínicas e histológicas en la encía, de las cuales que el absceso gingival la patología más frecuente (63,2 % de los casos. Tomando en cuenta el incremento del consumo de drogas en nuestra sociedad y los resultados obtenidos, es importante que el odontólgo relacione el uso de las drogas como un agente causal de alteraciones en la encía.The abuse of drugs, and among them of BASUCO, is one of the great public health problems our communioty has to face. 40 Wistar strain rats were used in this study: 20 with an experimental character and 20 as controls. Distilled water was utilized during 16 weeks. It was demonstrated that there is a direct relationship between the use of BASUCO and the clinical and histological alterations of the gingiva, of which the gingival abscess is the most frequent pathology (63.2 % of the cases. Taking into account the increasing consumption of drugs in our society and the results obtained, it is important that the odontologist considers the use of drugs as a causal agent of gingival alterations.

  19. Prevalencia de Chlamydia Trachomatis como agente causal de Leucorrea único o en asociación con otros agentes en Mujeres Embarazadas

    OpenAIRE

    Benavides, María Dolores; Téllez, Aleyda; Matus, Gregorio; Baltodano Martínez, Yubelka Susana; Centeno Cárdenas, Nora María

    2008-01-01

    El objetivo del presente estudio fue, identificar la prevalencia de Chlamydia Trachomatis como agente causal único o en asociación con otros agentes causales de Leucorrea en mujeres embarazadas ingresadas en el servicio de ARO del HEODRA, en el período de Agosto de 2007 a Enero de 2008. El estudio es descriptivo, de corte transversal. Se trabajó con fuentes primarias, a través de la entrevista y exploración ginecológica de las pacientes, y secundarias, a través de la revisión de los resultado...

  20. Detection of Colletotrichum acutatum Latent Infections in Strawberry Petioles and Leaves

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    Nataša Duduk

    2008-01-01

    Full Text Available Colletotrichum acutatum is the most significant agent of anthracnose strawberry fruit rot. Besides being a necrotrophic pest, it can spend a part of its life cycle as an epiphyte, in a form of latent infection. The presence of the fungi on symptomless plant tissue is considered one of the main ways of distribution of this economically harmful pathogen in the world. Investigation of latent C. acutatum infection was carried out on artificially inoculated strawberries. The initiation of fungi sporulation on symptomless petioles and leaves was carried out by exposing them to the herbicide paraquat (0.25% and low temperatures, which caused plant tissue decay in different ways. Surface sterilization with 0.5% NaOCl precedes the exposure of plant material to paraquat. The freezing procedure was carried out by exposure of plant material to the temperature of -20°C for 2h. After the freezing, one group was rinsed in Tween 20 (18 μl/l, and another group underwent surface sterilization in 0.0525% NaOCl with an addition of Tween 20 (18 μl/l. After 6 days of incubation, the appearance of acervuli and conidia was detected in 93.33 to 100% plant parts exposed to paraquat treatment and freezing procedure. In inoculated parts which were not exposed to herbicides or low temperatures, the presence of acervuli was detected in 3.33% tested petioles and 6.67% leaves.

  1. Analysis of genetic diversity of Fusarium tupiense, the main causal agent of mango malformation disease in southern Spain

    Science.gov (United States)

    Mango malformation disease (MMD) has become an important global disease affecting this crop. The aim of this study was to identify the main causal agents of MMD in the Axarquía region of southern Spain and determine their genetic diversity. Fusarium mangiferae was previously described in the Axarquí...

  2. Complete genome sequence of Spiroplasma citri strain R8-A2T, causal agent of stubborn disease in Citrus spp

    Science.gov (United States)

    Spiroplasma citri is the causal agent of stubborn disease in Citrus spp., as well as the cause of diseases in numerous other plant genera. Here we report the nucleotide sequence of the 1,599,709 bp circular chromosome and two plasmids of strain R8-A2T. This information will facilitate comparative ...

  3. Eutypa lata, causal agent of dieback in red currant (Ribes rubrum) and gooseberry (R. uva-crispa) in the Netherlands

    NARCIS (Netherlands)

    Wenneker, M.; Raak, van M.; Brouwershaven, van I.R.; Martin, W.S.; Kox, L.F.F.

    2011-01-01

    Dieback of red currant (Ribes rubrum) and gooseberry (Ribes uva-crispa) is an increasing problem in commercial fields in the Netherlands. Field surveys were done in 2006–2007 and samples with dieback symptoms were analysed. In this study the causal agent was diagnosed as Eutypa lata, based on

  4. White rot of garlic and onion (Causal agent, Sclerotium cepivorum): A status report from the Pacific Northwest

    Science.gov (United States)

    There is evidence from literature, state department of agriculture documents, and recent diagnoses that Sclerotium cepivorum, causal agent of white rot of garlic and onion, is spreading and/or becoming more established in the Pacific Northwest. Previously documented distributions are summarized, an...

  5. Morphological and molecular characterization of the causal agent of downy mildew on Quinoa (Chenopodium quinoa).

    Science.gov (United States)

    Choi, Young-Joon; Danielsen, Solveig; Lübeck, Mette; Hong, Seung-Beom; Delhey, Rolf; Shin, Hyeon-Dong

    2010-05-01

    Downy mildew is an economically important and widespread disease in quinoa (Chenopodium quinoa) growing areas. Although in many studies Peronospora farinosa is most commonly regarded as the causal agent of the disease, identification and classification of the pathogen remain still uncertain due to its taxonomic confusion. Thirty-six Peronospora isolates from quinoa with different geographic origins including Argentina, Bolivia, Denmark, Ecuador, and Peru were morphologically and molecularly compared with Peronospora species from other Chenopodium species. The morphology of three herbarium specimens was similar to that of P. variabilis, which originated from C. album, characterized by flexuous to curved ultimate branchlets and pedicellated conidia. Phylogenetic analysis based on ITS rDNA sequences also placed the quinoa pathogen within the same clade as P. variabilis. Within the ITS rDNA sequences of the quinoa pathogens, two base substitutions were found, which separated the majority of the Danish isolates from isolates from South America, but no sequence difference was found among the isolates from different cultivars of quinoa. The present results indicate that the pathogen responsible for the quinoa downy mildew is identical to Peronospora variabilis and that it should not be lumped with P. farinosa as claimed previously by most studies.

  6. Current Perspectives on Mycobacterium farcinogenes and Mycobacterium senegalense, the Causal Agents of Bovine Farcy

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    Mohamed E. Hamid

    2014-01-01

    Full Text Available Mycobacterium farcinogenes and M. senegalense are the causal agents of bovine farcy, a chronic, progressive disease of the skin and lymphatics of zebu cattle. The disease, which is prevalent mainly in sub-Saharan Africa, was in earlier times thought to be caused by Nocardia farcinica and can be described as one of the neglected diseases in cattle. Some aspects of the disease have been investigated during the last five decades but the major development had been in the bacteriological, chemotaxonomic, and phylogenetic aspects. Molecular analyses confirmed that M. farcinogenes and M. senegalense fall in a subclade together with M. houstonense and M. fortuitum. This subclade is closely related to the one accommodating M. peregrinum, M. porcinum, M. septicum, M. neworleansense, and M. alvei. DNA probes were designed from 16S-23S rRNA internal transcribed spacer and could be used for the rapid diagnosis of bovine farcy. An ELISA assay has been evaluated for the serodiagnosis of the disease. The zoonotic potentials of M. farcinogenes and M. senegalense are unknown; few studies reported the isolation of M. senegalense and M. farcinogenes from human clinical sources but not from environmental sources or from other domestic or wild animals.

  7. FUNGITOXICITY OF ESSENTIAL OILS ON PLASMOPARA VITICOLA,CAUSAL AGENT OF GRAPEVINE DOWNY MILDEW

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    RÉGIS DE OLIVEIRA FIALHO

    2017-10-01

    Full Text Available ABSTRACT This study aimed to evaluate the fungitoxic (antifungal effect of seven essential oils on Plasmopara viticola, the causal agent of grapevine downy mildew. The cinnamon, eucalyptus globulus, marjoram, melaleuca, peppermint, oregano and white thyme essential oils were compared with the mancozeb + metalaxyl-M fungicide. Three experiments were conducted to evaluate the effect of essential oils on spore germination. The first experiment evaluated the effect of direct contact of essential oils on the pathogen; the second evaluated the effect of volatile compounds on the pathogen and the third assessed the behavior of essential oils, when applied to vine leaves in field conditions, on the pathogen. All essential oils inhibited the spores’ germination, but in varying degrees, in addition, presenting fungistatic activity. All the essential oils showed chemical instability when the incubation time or the interval between products application where increased, all oils decrease antifungal activity percentage. Noteworthy, the cinnamon and the eucalyptus globulus essential oils were the most fungitoxic (antifungal on P. viticola.

  8. Erwinia amylovora – the Causal Agent of Root Collar Necrosis of Apple Trees

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    Veljko Gavrilović

    2008-01-01

    Full Text Available A large-scale outbreak of fire blight symptoms caused by Erwinia amylovora was recorded in pome fruit trees during 2007. In addition to fruit necrosis and shoot blight as the typical disease symptoms, dark purple necrosis was observed in the root collar area girdling the trunk just above the ground and thus withering the whole apple tree. Since similar symptoms on apple trees could be caused by E. amylovora or one of several phytopathogenic fungi of the genera Phomopsis and Phytophthora, an investigation was conducted to identify the causal agent of this disease. Levan-producing, nonfluorescent bacteria were isolated from diseased samples. The isolated strains produced HR in tobacco leaves and necrosis of artificially inoculated, immature pear fruits, followed by oozing of bacterial exudate, a characterisitic of E. amylovora. Based on the results of pathogenicity tests, biochemical characteristics, ELISA test and PCR analysis, it was confirmed that the investigated strainsbelonged to E. amylovora, causing the root collar necrosis of apple trees as an atypical symptom of this bacterium in Serbia. The explanation of this symptom may be that the vegetative rootstocks were infected with E. amylovora. Therefore, the development of diagnostic protocols for detection of E. amylovora in apple rootstock is very important for health inspections of planting materials.

  9. Tetranychus urticae (Acari: Tetranychidae) transmits Acidovorax citrulli, causal agent of bacterial fruit blotch of watermelon.

    Science.gov (United States)

    Choi, Okhee; Park, Jung-Joon; Kim, Jinwoo

    2016-08-01

    The two-spotted spider mite (TSSM) Tetranychus urticae is one of the most important pests of cucurbit plants. If TSSM can act as vector for Acidovorax citrulli (Acc), causal agent of bacterial fruit blotch (BFB), then the movement of mites from infected to healthy plants may represent a potential source of inocula for BFB outbreaks. To confirm the association between Acc and TSSM, we generated a green fluorescent protein-tagged mutant strain (Acc02rf) by transposon mutagenesis and demonstrated that TSSM can transmit Acc from infected to non-infected watermelon plants. Challenge with 10 TSSMs carrying Acc02rf population densities of 1.3 × 10(3) CFU each on freshly grown individual watermelon plants caused disease transmission to 53 %. Incubation periods ranged 7-9 days. Bacteria recovered from symptoms typical of those associated with leaf necrosis were characterized and identified as Acc. To our knowledge, this is the first report showing that TSSM can be a vector of Acc. The results reported here support that the strong association of TSSM with Acc is of particular importance in controlling BFB.

  10. Characterization, In Vitro Culture, and Molecular Analysis of Thecaphora solani, the Causal Agent of Potato Smut.

    Science.gov (United States)

    Andrade, Orlando; Muñoz, Gastón; Galdames, Rafael; Durán, Paola; Honorato, Rodrigo

    2004-08-01

    ABSTRACT The fungus Thecaphora solani (syn.: Angiosorus solani), the causal agent of potato smut, was cultivated in vitro for the first time. Teliospores obtained from galls of infected potato plants were used to inoculate commonly used solid and liquid media. The teliospores produced two kinds of vegetative tissue depending on the nutrient status of the media. A very slow radial-growing, hyaline, and septate mycelium, as usually seen in most of the in vitro-cultivated filamentous fungi, was obtained in wateragar medium after 30 to 40 days. On the other hand, a white, sponge-like mycelial mass was obtained in HCM + 1% activated charcoal, and on common potato dextrose agar or malt-yeast-peptone solid or liquid media, after 40 to 50 days under lab conditions. The identity among teliospores and the sponge-like mycelial mass was corroborated by DNA fingerprinting and partial sequencing of the large subunit (LSU) rDNA region. The sexual cycle of the pathogen was completed under lab conditions based on the development of teliospores on the sponge-like mycelial mass. The first attempt to reproduce the disease under controlled conditions was successful, inducing a gall in a cv. Desirée potato explant cultivated in vitro inoculated with radial-growing mycelia. Phylogenetic analysis of LSU rDNA data of the genus Thecaphora and other smut fungi confirmed the initial classification of the pathogen as T. solani.

  11. Aleppo pine knot disease: histology of the knots, detection of causal agent and mode of transmission

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    ROBERTO CALAMASSI

    2008-07-01

    Full Text Available Knot disease of Aleppo pine (Pinus halepensis subsp. halepensis occurs in the western range of the host in the Mediterranean region. The disease, originally named Aleppo pine tuberculosis (from tubercle, i.e. knot by Petri in 1924, causes a hyperplastic growth on the twigs and small branches, with knots that initially are small, green and lignified, and expand to 5–6 cm diameter at maturity. These knots have been associated with various bacterial species. In this study, only one bacterium was isolated from Aleppo pine knots, and this bacterium was constantly associated with the pine weevil Pissodes castaneus. The hyperplastic growth started either in the cortex or in the xylem, while the knot was formed in the cortical parenchyma. Bacteria were grouped in zoogloeae in the intercellular spaces or inside lysigenous cavities. Bacterial microcolonies have also been observed in the parenchyma cells. Inoculation of two of the bacterial strains on healthy Aleppo pine twigs did not induce knot formation. Knots did however form when adults of P. castaneus were externally contaminated with the bacteria and were then allowed to feed on pine saplings. These latter knots contained the same bacterial isolate as that which had been used to contaminate the weevils. All the isolates examined were tentatively assigned to the genus Erwinia. As this bacterium seems to be the causal agent of Aleppo pine knot disease, its complete identification and characterisation is needed.

  12. Monitoring the infective process of the downy mildew causal agent within micropropagated rose plants

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    Sonia Yamile Gómez

    2012-08-01

    Full Text Available Downy mildew in the rose caused by a species of the Peronospora genus is a very restrictive disease for the Colombian greenhouse rose production. The damage observed in the susceptible varieties of commercial rose include symptoms affect young steams and tiny leaves causing reddish and brown spots and defoliation; leading to 10% production losses. The infective behavior of this pathogen was studied with the aim of increasing the knowledge about the biology of the rose downy mildew. The study of the infective process was performed on the Charlotte variety using micropropagated roses inoculated with suspensions of sporangia. A germinal tube was observed during the germination process, it came from a lateral papilla and reached up to 300 microns in length. During this study, the ability of the pathogen to use vascular sieves as communication systems within the plant was determined. Oogonia and antheridia were also observed inside the epidermal cells, and oospores inside the parenchymal tissue close to xylem vessels. To the best of our knowledge, these sexual structures have not been reported on in Colombia before. This study verifies the ability of the downy mildew causal agent to move through the xylem vessels and produce sexual structures, such as oogonia, antheridia and oospores within those tissues.

  13. Potential of Pest and Host Phenological Data in the Attribution of Regional Forest Disturbance Detection Maps According to Causal Agent

    Science.gov (United States)

    Spruce, Joseph; Hargrove, William; Norman Steve; Christie, William

    2014-01-01

    Near real time forest disturbance detection maps from MODIS NDVI phenology data have been produced since 2010 for the conterminous U.S., as part of the on-line ForWarn national forest threat early warning system. The latter has been used by the forest health community to identify and track many regional forest disturbances caused by multiple biotic and abiotic damage agents. Attribution of causal agents for detected disturbances has been a goal since project initiation in 2006. Combined with detailed cover type maps, geospatial pest phenology data offer a potential means for narrowing the candidate causal agents responsible for a given biotic disturbance. U.S. Aerial Detection Surveys (ADS) employ such phenology data. Historic ADS products provide general locational data on recent insect-induced forest type specific disturbances that may help in determining candidate causal agents for MODIS-based disturbance maps, especially when combined with other historic geospatial disturbance data (e.g., wildfire burn scars and drought maps). Historic ADS disturbance detection polygons can show severe and extensive regional forest disturbances, though they also can show polygons with sparsely scattered or infrequent disturbances. Examples will be discussed that use various historic disturbance data to help determine potential causes of MODIS-detected regional forest disturbance anomalies.

  14. Evidence for Systemic Infection by Puccinia horiana, Causal Agent of Chrysanthemum White Rust, in Chrysanthemum.

    Science.gov (United States)

    Bonde, M R; Murphy, C A; Bauchan, G R; Luster, D G; Palmer, C L; Nester, S E; Revell, J M; Berner, D K

    2015-01-01

    Puccinia horiana, causal agent of the disease commonly known as chrysanthemum white rust (CWR), is a quarantine-significant fungal pathogen of chrysanthemum in the United States and indigenous to Asia. The pathogen was believed to have been eradicated in the United States but recently reappeared on several occasions in northeastern United States. The objective of the study presented here was to determine whether P. horiana could systemically infect chrysanthemum plants, thus providing a means of survival through winters. Scanning and transmission electron microscopy revealed the development of P. horiana on the surface and within leaves, stems, or crowns of inoculated chrysanthemum plants artificially exposed to northeastern U.S. winter temperatures. P. horiana penetrated leaves directly through the cuticle and then colonized the mesophyll tissue both inter- and intracellularly. An electron-dense material formed at the interface between fungal and host mesophyll cells, suggesting that the pathogen adhered to the plant cells. P. horiana appeared to penetrate mesophyll cell walls by enzymatic digestion, as indicated by the absence of deformation lines in host cell walls at penetration sites. The fungus was common in vascular tissue within the infected crown, often nearly replacing the entire contents of tracheid cell walls. P. horiana frequently passed from one tracheid cell to an adjacent tracheid cell by penetration either through pit pairs or nonpitted areas of the cell walls. Individual, presumed, fungal cells in mature tracheid cells of the crown and stems arising from infected crowns suggested that the pathogen might have been moving at least partially by means of the transpiration stream. The demonstration that chrysanthemum plants can be systemically infected by P. horiana suggests that additional disease control measures are required to effectively control CWR.

  15. In vitro Antifungal Activity of Different Plant Extracts against Phytophthora infestans the Causal Agent of Potato Late Blight

    OpenAIRE

    Saida Messgo-Moumene; Rym Boukhalfa; Djazia Belaïdi; Lyes Beninal; Siham Haddadj-Hamdi; Mohamed Bellatreche

    2017-01-01

    Our study aimed to evaluate the in vitro antifungal activity of aqueous extracts prepared from seven medicinal plants (Carya illinoinensis, Equisetum arvense, Rosmarinus officinalis, Pistacia lentiscus, Mentha suaveolens, Punica granatum, and Posidonia oceanica) against A1 and A2 isolates of Phytophthora infestans the causal agent of potato late blight. The crude (100%) plant extracts were prepared by decoction and tested at various concentrations (70, 50, 30 and 10% v/v) for dete...

  16. Revealing the Secrets of Colletotrichum acutatum with Special Focus on Secondary Metabolism and Population Genetics

    DEFF Research Database (Denmark)

    Amby, Daniel Buchvaldt

    Colletotrichum acutatum is an economically important fruit rot pathogen in strawberry. At the molecular level, little is known about the infection. In my PhD study, I therefore set to comprehensively understand the interaction between C. acutatum and strawberry fruits by applying multiple omic/hi...

  17. Structural modification of trans-cinnamic acid using Colletotrichum acutatum

    Directory of Open Access Journals (Sweden)

    Rodrigo Velasco B.

    2012-01-01

    Full Text Available Se estudió la biotransformación de ácido trans-cinámico mediante células completas del hongo fitopatógeno nativo colombiano Colletotrichum acutatum. Inicialmente, se evaluó la fungitoxicidad de este compuesto contraC. acutatum; el ácido trans-cinámico exhibió una toxicidad moderada a débil contra el microorganismo y aparentemente se presentó un mecanismo de detoxificación. Luego, para estudiar tal mecanismo y explorar la capacidad de este hongo para biotransformar el ácido trans-cinámico en productos con valor agregado, el microorganismo se incubó con el sustrato usando tres medios de cultivo diferentes (Czapeck-Dox, Sabouraud y PDB a condiciones ambientales. Usando el medio Czapeck-Dox, los cultivos completos de C.acutatum redujeron el ácido trans-cinámico, primero a aldehídos (transcinamaldehido y 3-fenilpropanal, luego a alcoholes (alcohol cinamílico y 3-fenil-1-propanol. Posteriormente, estos alcoholes fueron transformados a los correspondientes ésteres de acetilo. Sin embargo, algunos de estos productos estuvieron ausentes o presentes a una concentración diferente cuando se cambió el medio de cultivo. Los resultados sugieren un mecanismo de detoxificación en el cual el sistema carbonílico α,β-insaturado es afectado.Por otra parte, los productos metabólicos formados son compuestos útiles usados como fragancias y sabores. Por consiguiente, el metabolismo del ácido trans-cinámico usando C. acutatum puede proporcionar nuevos blancos metabólicos para controlar C. acutatum así como también una forma simple y eficiente para obtener sabores y perfumes, tales como el alcohol cinamílico y el 3-fenil-1-propanol, y sus ésteres de acetilo.

  18. Clarification on host range of Didymella pinodes the causal agent of pea ascochyta blight

    Directory of Open Access Journals (Sweden)

    Eleonora eBarilli

    2016-05-01

    Full Text Available Didymella pinodes is the principal causal agent of ascochyta blight, one of the most important fungal diseases of pea (Pisum sativum worldwide. Understanding its host specificity has crucial implications in epidemiology and management; however, this has not been clearly delineated yet. In this study we attempt to clarify the host range of D. pinodes and to compare it with that of other close Didymella spp. D. pinodes was very virulent on pea accessions, although differences in virulence were identified among isolates. On the contrary, studied isolates D. fabae, D. rabiei and D. lentil showed a reduced ability to infect pea not causing macroscopically visible symptoms on any of the pea accessions tested.D. pinodes isolates were also infective to some extend on almost all species tested including species such as Hedysarum coronarium, Lathyrus sativus, Lupinus albus, Medicago spp., Trifolium spp., Trigonella foenum-graecum and Vicia articulata which were not mentioned before as hosts of D. pinodes. On the contrary, D. lentil and D. rabiei were more specific, infecting only lentil and chickpea, respectively. D. fabae was intermediate, infecting mainly faba bean, but also slightly other species such as Glycine max, Phaseolus vulgaris, Trifolium spp., Vicia sativa and V. articulata.DNA sequence analysis of the nuclear ribosomal internal transcribed spacer region (ITS was performed to confirm identity of the isolates studies and to determine phylogenetic relationship among the Didymella species, revealing the presence of two clearly distinct clades. Clade one was represented by two supported subclusters including D. fabae isolates as well as D. rabiei with D. lentil isolates. Clade two was the largest and included all the D. pinodes isolates as well as Phoma medicaginis var. pinodella. Genetic distance between D. pinodes and the other Didymella spp. isolates was not correlated with overall differences in pathogenicity. Based on evidences presented here

  19. Host range of Phakopsora pachyrhizi, the causal agent of soybean rust

    Science.gov (United States)

    Phakopsora pachyrhizi, the causal organism of soybean rust, was first described in 1903 from leaves of Glycine max subsp. soja, or wild soybean, in Japan. Since that time, there have been numerous reports of the pathogen on various leguminous species around the world, first in Asia, followed by Aust...

  20. Development of novel microsatellites from Moniliophthora perniciosa, causal agent of the witches' broom disease of Theobroma cacao.

    Science.gov (United States)

    Silva, Jurema R Q; Figueira, Antonio; Pereira, Gonçalo A G; Albuquerque, Paulo

    2008-07-01

    Moniliophthora perniciosa is the causal agent of the witches' broom disease of cacao. Based on available genomic sequences, we identified 30 new microsatellite loci, which were analysed using 50 isolates from four populations sampled over a wide geographical area in Brazil, including three populations from the Amazon, the fungal putative centre of diversity, plus one from Bahia. Nine loci were polymorphic, with an average of 2.9 alleles per locus. The level of polymorphism observed was low, but these markers may allow the evaluation of pathogen diversity and the establishment of molecular standards for isolate fingerprinting to support cacao breeding. © 2007 The Authors. Journal compilation © 2007 Blackwell Publishing Ltd.

  1. ANTAGONISTIC EFFECT OF FOUR FUNGAL ISOLATES TO GANODERMA BONINENSE, THE CAUSAL AGENT OF BASAL STEM ROT OF OIL PALM

    Directory of Open Access Journals (Sweden)

    OKKY SETYAWATI DHARMAPUTRA

    1990-01-01

    Full Text Available Four fungal isolates from soils obtained from three sites of the oil palm plantations in North Sumatra were found antagonistic to Ganoderma boninense, the causal agent of basal stem rot of oil palm. Penicillium citrinum inhibited the growth of the pathogen and formed a zone of inhibition on the agar media. Trichoderma harzianum BIO - 1 as well as BIO - 2 and T. viride not only repressed the growth of the pathogen but also caused lysis of the hyphae, and the colony was totally overgrown by the antagonists.

  2. Producción in vitro de pectinasas por Colletotrichum acutatum In vitro production of pectinases by Colletotrichum acutatum

    Directory of Open Access Journals (Sweden)

    Carlos Patiño Torres

    2010-01-01

    Full Text Available Los hongos del género Colletotrichum son reconocidos productores de sustancias fifitotóxicas de bajo peso molecular y de enzimas que juegan papeles clave en su interacción patogénica con varios cultivos. Este estudio tuvo como objetivo determinar la naturaleza de las sustancias fitotóxicas producidas por C. acutatum en los medios de cultivo líquido Czapeck-Dox, Fries y MS, que estuviesen implicados en su interacción patogénica con el tomate de árbol (Solanum betaceae. Los procedimientos y resultados de la evaluación permitieron descartar que la actividad fitotóxica observada sobre los frutos de tomate inoculados con los extractos de los medios de cultivo se debiera a metabolitos de bajo peso molecular. Por el contrario, utilizando la prueba de placa de pozos (Dingle et al., 1953 se estableció que C. acutatum produce en los medios de cultivo evaluados enzimas con actividad pectinasa, tanto liasas como hidrolasas, las cuales podrían estar implicadas en la enfermedad de la antracnosis del tomate de árbol. Los resultados demostraron además que la producción de las enzimas se ve influenciada por el pH del medio de cultivo.The fungi of gender Colletotrichum are producers of phytotoxic substances of low molecular weight and enzymes, which can to play crucial roles in their pathogenic relations with many commercial crops. This study was realized for to determine the type of the substances produced by C. acutatum in the Czapeck-Dox’s, Fries’s and MS’s culture medium, substances that have roles in the pathogenic relations with tamarillo (Solanum betaceae. The procedures and results of the evaluation allowed us to discard that phytotoxic activity on tamarillo fruits inoculated with extracts to be low molecular weight metabolites. Utilizing the cup-plate asay (Dingle et al., 1953, we to establish what in vitro, C. acutatum produced enzymes like pectinases (poligalacturonases and pectyn lyases, whose action can to be implied in the

  3. The Born Rule and Free Will: why Libertarian Agent-Causal Free Will is not "antiscientific"

    Science.gov (United States)

    Kastner, Ruth E.

    In the libertarian "agent causation" view of free will, free choices are attributable only to the choosing agent, as opposed to a specific cause or causes outside the agent. An often-repeated claim in the philosophical literature on free will is that agent causation necessarily implies lawlessness, and is therefore "antiscientific." That claim is critiqued and it is argued, on the contrary, that the volitional powers of a free agent need not be viewed as anomic, specifically with regard to the quantum statistical law (the Born Rule). Assumptions about the role and nature of causation, taken as bearing on volitional agency, are examined and found inadequate to the task. Finally, it is suggested that quantum theory may constitute precisely the sort of theory required for a nomic grounding of libertarian free will.

  4. Ultrastructure of the early stages of Colletotrichum acutatum infection of strawberry tissues

    National Research Council Canada - National Science Library

    Arroyo, Francisco T; Moreno, Javier; Garcia-Herdugo, Gregorio; Santos, Berta D.l; Barrau, Carmen; Porras, Maria; Blanco, Cesar; Romero, Fernando

    2005-01-01

    The early stages of the infection of attached leaves and petioles of strawberry (Fragaria ×ananassa Duch. 'Camarosa') by Colletotrichum acutatum Simmonds were studied using scanning and transmission electron microscopy...

  5. Species-specific detection and identification of fusarium species complex, the causal agent of sugarcane pokkah boeng in China.

    Directory of Open Access Journals (Sweden)

    Zhenyue Lin

    Full Text Available BACKGROUND: Pokkah boeng disease caused by the Fusarium species complex results in significant yield losses in sugarcane. Thus, the rapid and accurate detection and identification of the pathogen is urgently required to manage and prevent the spreading of sugarcane pokkah boeng. METHODS: A total of 101 isolates were recovered from the pokkah boeng samples collected from five major sugarcane production areas in China throughout 2012 and 2013. The causal pathogen was identified by morphological observation, pathogenicity test, and phylogenetic analysis based on the fungus-conserved rDNA-ITS. Species-specific TaqMan real-time PCR and conventional PCR methods were developed for rapid and accurate detection of the causal agent of sugarcane pokkah boeng. The specificity and sensitivity of PCR assay were also evaluated on a total of 84 isolates of Fusarium from China and several isolates from other fungal pathogens of Sporisorium scitamineum and Phoma sp. and sugarcane endophyte of Acremonium sp. RESULT: Two Fusarium species (F. verticillioides and F. proliferatum that caused sugarcane pokahh boeng were identified by morphological observation, pathogenicity test, and phylogenetic analysis. Species-specific TaqMan PCR and conventional PCR were designed and optimized to target their rDNA-ITS regions. The sensitivity of the TaqMan PCR was approximately 10 pg of fungal DNA input, which was 1,000-fold over conventional PCR, and successfully detected pokkah boeng in the field-grown sugarcane. CONCLUSIONS/SIGNIFICANCE: This study was the first to identify two species, F. verticillioides and F. proliferatum, that were causal pathogens of sugarcane pokkah boeng in China. It also described the development of a species-specific PCR assay to detect and confirm these pathogens in sugarcane plants from mainland China. This method will be very useful for a broad range of research endeavors as well as the regulatory response and management of sugarcane pokkah boeng.

  6. Characterization of Mycobacterium salmoniphilum as causal agent of mycobacteriosis in Atlantic salmon, Salmo salar L., from a freshwater recirculation system.

    Science.gov (United States)

    Aro, L; Correa, K; Martínez, A; Ildefonso, R; Yáñez, J M

    2014-04-01

    Thirty Atlantic salmon, Salmo salar L., with low corporal condition relative to other fish present in the culture system, were sampled from a freshwater recirculation pisciculture located in Chile. The most characteristic signs and lesions were cachexia and presence of multiple greyish-white granulomas within internal organs. The external and internal lesions, along with the microscopic, histologic and biochemical findings, were consistent with mycobacteriosis. The identification of Mycobacterium salmoniphilum as the causal agent of the lesions was possible through the use of molecular analyses. This study represents the first report of Mycobacterium salmoniphilum in a freshwater recirculation system and the first case of fish mycobacteriosis described in Chile. © 2013 John Wiley & Sons Ltd.

  7. The potato dry rot causal agent and severity in Ardabil storages and the resistance of cultivars to the disease

    Directory of Open Access Journals (Sweden)

    Leila Khoshnevis

    2016-09-01

    Full Text Available Introduction: Dry rot is one of the most important diseases of potato in storages. The aim of this study was to determine dry rot severity in potato storages of Ardabil, identify the disease causal agents and evaluate some potato cultivars resistance to the disease. Materials and methods: Totally 150 infected samples were collected from thirty nine studied storages in Ardabil. Dry rot severity and the prevalence of infected tubers were determined by surveying three 50 kg bags of potato in the storages. Fungi isolated and purified from the tubers with dry rot symptoms. A factorial design with four replications was applied in order to evaluate the reaction of five potato cultivars to four Fusarium species and determining the resistant one to dry rot. Potato tuber slices were inoculated by conidial suspension of Fusarium species. Four days after inoculation and maintaining in darkness and 25oC, the cultivars susceptibility was  identified. Results: Four species of Fusarium were identified as dry rot causal agents in Ardabil as follows: F. oxysporum, F. poae, F. solani and F. sporotrichioides. There was no significant difference between Fusarium species in pathogenicity. The reaction of cultivars to various Fusarium species was different. Boren had the lowest infection (12.5% and Sabalan showed the highest (98.87 %. Sabalan ،Khavaran ،Agria and hybrid line 3970093 displayed the highest susceptibility to various studied Fusarium species. Discussion and conclusion: Based on the results, Boren is introduced as the most resistant cultivar to Fusarium dry rot and Sabalan, Agria and hybrid line 3970093 as the susceptible ones.

  8. Amebae and ciliated protozoa as causal agents of waterborne zoonotic disease.

    Science.gov (United States)

    Schuster, Frederick L; Visvesvara, Govinda S

    2004-12-09

    The roles free-living amebae and the parasitic protozoa Entamoeba histolytica and Balantidium coli play as agents of waterborne zoonotic diseases are examined. The free-living soil and water amebae Naegleria fowleri, Acanthamoeba spp., and Balamuthia mandrillaris are recognized etiologic agents of mostly fatal amebic encephalitides in humans and other animals, with immunocompromised and immunocompetent hosts among the victims. Acanthamoeba spp. are also agents of amebic keratitis. Infection is through the respiratory tract, breaks in the skin, or by uptake of water into the nostrils, with spread to the central nervous system. E. histolytica and B. coli are parasitic protozoa that cause amebic dysentery and balantidiasis, respectively. Both intestinal infections are spread via a fecal-oral route, with cysts as the infective stage. Although the amebic encephalitides can be acquired by contact with water, they are not, strictly speaking, waterborne diseases and are not transmitted to humans from animals. Non-human primates and swine are reservoirs for E. histolytica and B. coli, and the diseases they cause are acquired from cysts, usually in sewage-contaminated water. Amebic dysentery and balantidiasis are examples of zoonotic waterborne infections, though human-to-human transmission can occur. The epidemiology of the diseases is examined, as are diagnostic procedures, anti-microbial interventions, and the influence of globalization, climate change, and technological advances on their spread.

  9. Non- dermatophytes as emerging opportunistic causal agents of superficial mycoses at Balaghat (M.P

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    S M Singh

    1990-01-01

    Full Text Available A clinico-mycological study of 75 suspected cases of superficial mycoses occurring at Balaghat (MP was done. Out of these 51 cases were both KOH as well as culture positive. Among these 51 cases, 33 were of onychomycosis and in the rest of the cases either skin and/ or both nails were infected. Among the isolates recovered, 27 were of dermatophytes, 22 non- dermatophytes and 4 yeasts. Trichophyton rubrum was the only species recovered among dermatophytes. The most prevalent among non dermatophytes were Hendersonula toruloidea. Microascus cinereus, Fusarium solani. Trichosporon sp. Canadida Curvularia lunate, Chaetophoma dermo-unquis, Geosmithia putterilli. Eupenicillum pervum, Phialophora bubakii and Phoma multirostrata. The use of cycloheximide free medium is recommended in the isolation of non-dermatophyte aetiologic agent causing superficial mycoses.

  10. Variable Number of Tandem Repeat Markers in the Genome Sequence of Mycosphaerella Fijiensis, the Causal Agent of Black Leaf Streak Disease of Banana (Musa spp.)

    Science.gov (United States)

    Mycosphaerella fijiensis, the causal agent of banana leaf streak disease (commonly known as black Sigatoka), is the most devastating pathogen attacking bananas (Musa spp). Recently the whole genome sequence of M. fijiensis became available. This sequence was screened for the presence of Variable Num...

  11. Thermal inactivation of infested plants, nursery equipment, and soil is a management option for the treatment of Phytophthora ramorum, causal agent of sudden oak death

    Science.gov (United States)

    Wolfgang Schweigkofler; Vernon Huffman; Karen Suslow; Kathleen Kosta

    2017-01-01

    Infected nursery plants play an important role in the spread of Phytophthora ramorum , the causal agent of sudden oak death and ramorum blight. In order to minimize the risk for disease transmission to new areas, nurseries are inspected regularly for P. ramorum , and federal regulations require the eradication of...

  12. Revealing the Secrets of Colletotrichum acutatum with Special Focus on Secondary Metabolism and Population Genetics

    DEFF Research Database (Denmark)

    Amby, Daniel Buchvaldt

    Colletotrichum acutatum is an economically important fruit rot pathogen in strawberry. At the molecular level, little is known about the infection. In my PhD study, I therefore set to comprehensively understand the interaction between C. acutatum and strawberry fruits by applying multiple omic...

  13. Presencia de Blastocystis Hominis como agente causal de enfermedades gatrointestinales en la comuna 7 (Gaira del Distrito de Santa Marta

    Directory of Open Access Journals (Sweden)

    Sonja Liliana Lozano Socarras

    2013-10-01

    Full Text Available La Blastocystis hominis es un protozoo que causa cuadros diarreicos. Es altamente prevalente en poblaciones que no cuentan con servicios adecuados de higiene, alcantarillado y salud pública. La infección con Blastocystis hominis frecuentemente concomita con otros enteropatógenos de reconocida patogenicidad, además se ha reportado como parásito oportunista en pacientes con VIII SIDA. El objetivo del presente estudio es determinar la presencia de Blastocystis hominis en pacientes de consulta externa con síntomas asociados a enfermedades gastrointestinales, en la comuna 7 del distrito de Santa Marta, Colombia, durante el mes de Enero a Diciembre de 2004. El método de diagnóstico utilizado fue examen coproparasitológico seriado y el número de pacientes analiza-dos fue de 291. Los resultados muestran una alta presencia de Blastocystis hominken pacientes con enfermedad diarreica residentes en Gaira. Un alto porcentaje de la población parasitada (62,6% presento como único agente causal de la enfermedad diarreica al Blastocystis hominis lo que sugiere la presencia de otras enfermedades que pueden involucrar un compromiso inmunológico, el efecto será una respuesta inmune débil contra el parásito.

  14. Production of calcium oxalate crystals by the basidiomycete Moniliophthora perniciosa, the causal agent of witches' broom disease of Cacao.

    Science.gov (United States)

    Rio, Maria Carolina S do; de Oliveira, Bruno V; de Tomazella, Daniela P T; Silva, José A Fracassi da; Pereira, Gonçalo A G

    2008-04-01

    Oxalic acid has been shown as a virulence factor for some phytopathogenic fungi, removing calcium from pectin and favoring plant cell wall degradation. Recently, it was published that calcium oxalate accumulates in infected cacao tissues during the progression of Witches' Broom disease (WBD). In the present work we report that the hemibiotrophic basidiomycete Moniliophthora perniciosa, the causal agent of WBD, produces calcium oxalate crystals. These crystals were initially observed by polarized light microscopy of hyphae growing on a glass slide, apparently being secreted from the cells. The analysis was refined by Scanning electron microscopy and the compositon of the crystals was confirmed by energy-dispersive x-ray spectrometry. The production of oxalate by M. perniciosa was reinforced by the identification of a putative gene coding for oxaloacetate acetylhydrolase, which catalyzes the hydrolysis of oxaloacetate to oxalate and acetate. This gene was shown to be expressed in the biotrophic-like mycelia, which in planta occupy the intercellular middle-lamella space, a region filled with pectin. Taken together, our results suggest that oxalate production by M. perniciosa may play a role in the WBD pathogenesis mechanism.

  15. Dieback of rose caused by Acremonium sclerotigenum as a new causal agent of rose dieback in Iran

    Energy Technology Data Exchange (ETDEWEB)

    Mirtalebi, M.; Banihashemi, Z.; Sabahi, F.; Mafakheri, H.

    2016-07-01

    Severe dieback of rose has been recently observed in several rose greenhouses in Fars province of Iran. During 2014 and 2015, stems of rose plants showing yellow to brown discoloration and dieback were collected from rose greenhouses. Coniothyrium fuckelii, Botrytis cinerea and Acremonium were subsequently isolated from the margin between healthy and symptomatic tissue. B. cinerea and C. fuckelii isolates were similar to those previously reported for dieback of rose worldwide. Morphological and cultural characters along with molecular analysis based on partial sequences of the internal transcribed spacer (ITS) region of the ribosomal RNA genome allowed confirming the affiliation of the Acremonium isolates, corresponding to A. sclerotigenum as a new causal agent of rose dieback. To determine its pathogenicity on rose, Koch's postulates were fulfilled by stem inoculation of nine rose cultivars under greenhouse conditions. While A. sclerotigenum is considered as a soil-born pathogen, and produces sclerotia that are resistant to adverse conditions enables the fungus to survive extended period in soil, propagule trapping in our study revealed that conidia can become airborn, imply that an aerial phase, forms an important component of the disease cycle.

  16. Relationships between altitude, triatomine (Triatoma dimidiata) immune response and virulence of Trypanosoma cruzi, the causal agent of Chagas' disease.

    Science.gov (United States)

    DE Fuentes-Vicente, J A; Cabrera-Bravo, M; Enríquez-Vara, J N; Bucio-Torres, M I; Gutiérrez-Cabrera, A E; Vidal-López, D G; Martínez-Ibarra, J A; Salazar-Schettino, P M; Córdoba-Aguilar, A

    2017-03-01

    Little is known about how the virulence of a human pathogen varies in the environment it shares with its vector. This study focused on whether the virulence of Trypanosoma cruzi (Trypanosomatida: Trypanosomatidae), the causal agent of Chagas' disease, is related to altitude. Accordingly, Triatoma dimidiata (Hemiptera: Reduviidae) specimens were collected at three different altitudes (300, 700 and 1400 m a.s.l.) in Chiapas, Mexico. The parasite was then isolated to infect uninfected T. dimidiata from the same altitudes, as well as female CD-1 mice. The response variables were phenoloxidase (PO) activity, a key insect immune response, parasitaemia in mice, and amastigote numbers in the heart, oesophagus, gastrocnemius and brain of the rodents. The highest levels of PO activity, parasitaemia and amastigotes were found for Tryp. cruzi isolates sourced from 700 m a.s.l., particularly in the mouse brain. A polymerase chain reaction-based analysis indicated that all Tryp. cruzi isolates belonged to a Tryp. cruzi I lineage. Thus, Tryp. cruzi from 700 m a.s.l. may be more dangerous than sources at other altitudes. At this altitude, T. dimidiata is more common, apparently because the conditions are more beneficial to its development. Control strategies should focus activity at altitudes around 700 m a.s.l., at least in relation to the region of the present study sites. © 2016 The Royal Entomological Society.

  17. Characterization of Phytophthora pistaciae, the causal agent of pistachio gummosis, based on host range, morphology, and ribosomal genome

    Directory of Open Access Journals (Sweden)

    Zahra MIRSOLEIMANI

    2014-01-01

    Full Text Available Gummosis is the most important disease of pistachio trees in Iranian pistachio orchards. Phytophthora pistaciae, the main causal agent of this disease, was isolated and described from Kerman province of Iran for the first time. The present study aimed to establish the host range, morphological characteristics and ribosomal genome of P. pistaciae isolates. During 2009–2010, isolates of P. pistaciae were sampled from 12 infected pistachio plantations in Kerman and Yazd provinces of Iran. Based on phylogenetic analysis of ITS regions, all isolates belonged to a monophyletic clade and clustered with P. pistaciae from other studies. The isolates were high temperature tolerant and produced non-papillate, ellipsoid to ovoid sporangia with polar caps, and were non-caducous, sympodial and had internal and external proliferation. The isolates were homothallic and produced spherical oogonia with smooth walls and paragynous, rarely amphigynous, spherical to ovoid antheridia. Oospores were spherical, colorless and aplerotic. Isolates generated chlamydospores in host tissues. The host range of P. pistaciae is not limited to pistachio species. Almond, walnut, apricot, grape, mango, sour cherry, among woody plants, and pea, different types of beans, chickpea, faba bean, safflower and okra, among herbaceous plants, were shown to be potential hosts of the pathogen. This study showed that isolates of P. pistaciae were homogenous in ITS rDNA genome and their host range, and morphological traits were similar. 

  18. Efficacy of Copper Compounds in Controlling Xanthomonas campestris pv. vesicatoria, the Causal Agent of Bacterial Spot of Pepper

    Directory of Open Access Journals (Sweden)

    Svetlana Milijašević

    2006-01-01

    Full Text Available The efficacy of several new formulations of copper compounds in controlling Xanthomonas campestris pv. vesicatoria in pepper was estimated in field conditions using artificial inoculation. The efficacies of Cuprozin 35 WP (copper-oxychloride and Blauvit(copper-hydroxide were tested in the localities Dobanovci and Kupinovo in 2005. Another two formulations, Cuproxat (copper-sulfate and Fungohem SC (copper-hydroxide, were tested along with the previous two in the localities Zemun and Smederevska Palanka in2006. Both bactericides tested in 2005 exhibited high efficacy in controlling X. c. pv. vesicatoria in both localities. However, there were no significant differences in the efficacy of Cuprozin 35 WP at higher concentration (74.3%-78.7% and Blauvit (74.6%-78.9% inthe two trials. Cuprozin 35 WP decreased efficacy, but a satisfactory effectiveness was still achieved at lower concentration (66.5%-66.5%. In the experiments conducted in 2006, higher concentration of Fungohem SC showed the highest efficacy (86.1%-89.1% in controllingbacterial spot of pepper. Blauvit, Cuprozin 35 WP and Cuproxat also exhibited high efficacy. However, there were no significant differences in the efficacy of these bactericides between the two localities. Fungohem SC applied at lower concentration was less effective (77.2%-80.0% but its efficacy was still good enough. Our experiments showed that copper bactericides based on copper-sulfate, copper-oxychloride and copper-hydroxide exhibited satisfactory efficacy in controlling the causal agent of bacterial spot of pepper in our climatic conditions.

  19. Development of Nested-PCR Assay to Detect Acidovorax citrulli, a Causal Agent of Bacterial Fruit Blotch at Cucurbitaceae

    Directory of Open Access Journals (Sweden)

    Young-Tak Kim

    2015-06-01

    Full Text Available The specific and sensitive nested-PCR method to detect Acidovorax citrulli, a causal agent of bacterial fruit blotch on cucurbitaceae, was developed. PCR primers were designed from the draft genome sequence which was obtained with the Next Generation Sequencing of A. citrulli KACC10651, and the nested-PCR primer set (Ac-ORF 21F/Ac-ORF 21R were selected by checking of specificity to A. citrulli with PCR assays. The selected nested-PCR primer amplified the 140 bp DNA only from A. citrulli strains, and detection sensitivity of the nested PCR increased 10,000 times of 1st PCR detection limit (10 ng genomic DNA/PCR. The nested PCR detected A. citrulli from the all samples of seed surface wash (external seed detection of the artificially inoculated watermelon seeds with 101 cfu/ml and above population of A. citrulli while the nested PCR could not detected A. citrulli from the mashed seed suspension (internal seed detection of the all artificially inoculated watermelon seeds. When the naturally infested watermelon seeds (10% seed infested rate with grow-out test used, the nested PCR detected A. citrulli from 2 seed samples out of 10 replication samples externally and 5 seed samples out of 10 replication samples internally. We believe that the nested-PCR developed in this study will be useful method to detect A. citrulli from the Cucurbitaceae seeds.

  20. ITS-rDNA phylogeny of Colletotrichum spp. causal agent of apple Glomerella leaf spot Filogenia por ITS-rDNA de Colletotrichum spp., agente causal da mancha foliar da Gala em macieira

    Directory of Open Access Journals (Sweden)

    Diorvania Ribeiro Giaretta

    2010-04-01

    Full Text Available Several diseases have affected apple production, among them there is Glomerella leaf spot (GLS caused by Colletotrichum spp. The first report of this disease in apple was in plants nearby citrus orchards in São Paulo State, Brazil. The origin of this disease is still not clear, and studies based on the molecular phylogeny could relate the organisms evolutionarily and characterize possible mechanisms of divergent evolution. The amplification of 5.8S-ITS (Internal Transcribed Spacer of rDNA of 51 pathogenic Colletotrichum spp. isolates from apples, pineapple guava and citrus produced one fragment of approximately 600 bases pairs (bp for all the isolates analyzed. The amplified fragments were cleaved with restriction enzymes, and fragments from 90 to 500bp were obtained. The sequencing of this region allowed the generation of a phylogenetic tree, regardless of their hosts, and 5 isolated groups were obtained. From the "in silico" comparison, it was possible to verify a variation from 93 to 100% of similarity between the sequences studied and the Genbank data base. The causal agent of GLS is nearly related (clustered to isolates of pineapple guava and to the citrus isolates used as control.A produção de maçã vem sendo comprometida pela ocorrência de muitas doenças, entre as quais se destaca a Mancha Foliar de Glomerella (MFG, causada por Colletotrichum spp. O primeiro relato dessa doença em maçã foi registrado em plantas próximas a pomares de citrus no Estado de São Paulo, Brasil. A origem da MFG ainda não está bem clara, e estudos baseados na filogenia permitirão relacionar o organismo evolutivamente, possibilitando caracterizar possíveis mecanismos divergentes de evolução. A amplificação da região 5.8S-ITS (espaçador interno transcrito do rDNA de 51 isolados de Colletotrichum patogênicos em de maçã, goiabeira serrana e citrus produziu um fragmento de aproximadamente 600 pares de bases (pb para todos os isolados analisados

  1. Sensitivity of Colletotrichum acutatum Isolates to Selected Fungicides

    Directory of Open Access Journals (Sweden)

    Barbora Jílková

    2015-01-01

    Full Text Available Laboratory tests of six isolates of the pathogen Colletotrichum acutatum from different host plants demonstrated the varying sensitivity of pathogen with regard to mycelium growth and conidial germination after treatment with seven fungicides containing various active ingredients. None of the evaluated isolates was tolerant to the selected active ingredients in the fungicides. In tests of mycelium growth sensitivity, isolates from lupin and strawberry were most frequently identified as the most sensitive of all evaluated fungicides. The safflower isolate, on the other hand, most frequently exhibited the lowest reaction to fungicides. Differences in conidial germination of individual isolates were not detected in fungicides with the active ingredients dithianon, folpet and mancozeb, for which inhibition reached 100% in almost all isolates. The most significant differences in sensitivity among individual isolates were recorded in fungicides with the active ingredients azoxystrobin and metiram. In the case of the fungicide with active ingredient azoxystrobin, the highest inhibitory effect was achieved in the safflower isolate and the lowest in the white lupin isolate. After treatment with the fungicide with active ingredient metiram, the lowest germination rate was recorded in isolates from safflower and strawberry and the highest in isolates from hypericum and lupin.

  2. Multisource causal data mining

    Science.gov (United States)

    Woodley, Robert; Gosnell, Michael; Shallenberger, Kevin

    2012-06-01

    Analysts are faced with mountains of data, and finding that relevant piece of information is the proverbial needle in a haystack, only with dozens of haystacks. Analysis tools that facilitate identifying causal relationships across multiple data sets are sorely needed. 21st Century Systems, Inc. (21CSi) has initiated research called Causal-View, a causal datamining visualization tool, to address this challenge. Causal-View is built on an agent-enabled framework. Much of the processing that Causal-View will do is in the background. When a user requests information, Data Extraction Agents launch to gather information. This initial search is a raw, Monte Carlo type search designed to gather everything available that may have relevance to an individual, location, associations, and more. This data is then processed by Data- Mining Agents. The Data-Mining Agents are driven by user supplied feature parameters. If the analyst is looking to see if the individual frequents a known haven for insurgents he may request information on his last known locations. Or, if the analyst is trying to see if there is a pattern in the individual's contacts, the mining agent can be instructed with the type and relevance of the information fields to look at. The same data is extracted from the database, but the Data Mining Agents customize the feature set to determine causal relationships the user is interested in. At this point, a Hypothesis Generation and Data Reasoning Agents take over to form conditional hypotheses about the data and pare the data, respectively. The newly formed information is then published to the agent communication backbone of Causal- View to be displayed. Causal-View provides causal analysis tools to fill the gaps in the causal chain. We present here the Causal-View concept, the initial research into data mining tools that assist in forming the causal relationships, and our initial findings.

  3. [Causal agents of onychomycosis].

    Science.gov (United States)

    Canteros, G E; Davel, G O; Vivot, W

    1994-01-01

    The results obtained with 307 specimens from putatively immunocompetent patients between May 1991 and May 1992 were reviewed, to determine the frequency of isolation of fungal species causing onychomycoses. Sixty eight percent of the specimen were positive for microscopic examination and/or cultures. Onychomycoses occurred with double frequency in women than in men (Table 1), and 77% of cases were diagnosed in patients aged between 30 and 70 years (Figure 1). Out of 182 patients with positive cultures, 60% were affected by dermatophytes and 39% by yeasts; molds (Aspergillus spp.) were isolated in only two cases (Table 3). Neither Corynebacterium spp., nor Malasezzia furfur were detected. In toe nails Trichophyton rubrum predominated over yeasts being isolated in 72.9% of the cases; yeasts other than Candida albicans were isolated in 12.3%, Trichophyton mentagrophytes in 10%, while Aspergillus spp., C. albicans and Epidermophyton floccosum in only 1.6%. On the other hand, in finger nails yeasts predominated: C. albicans was isolated in 46.7% of cases, other yeasts in 43.3%; and T. rubrum in the remaining 10%. Out of 41 isolations of yeasts other than C. albicans, 42% were C. parapsilosis, 16% Debaryomyces hansenii, 6% C. pulcherrima, 6% Trichosporum cutaneum and 6% C. famata (Figure 2).

  4. Nutritional Capability of and Substrate Suitability for Pseudogymnoascus destructans, the Causal Agent of Bat White-Nose Syndrome

    Science.gov (United States)

    Raudabaugh, Daniel B.; Miller, Andrew N.

    2013-01-01

    Pseudogymnoascus destructans, the causal agent of bat white-nose syndrome, has caused nearly six million deaths in North American bats since its introduction into the United States in 2006. Current research has shown that caves can harbor P. destructans even after the infected bats are removed and bats no longer visit or inhabit previously infected caves. Our research focuses on elucidating reservoir requirements by investigating the nutritional capabilities of and substrate suitability requirements for six different P. destructans isolates from various localities including Illinois, Indiana, New York (Type specimen), and Pennsylvania. Enzyme assays implicate that both urease and b-glucosidase appear to be constitutive, lipase and esterase activity were more rapid than proteinase activity on 6% gelatin, gelatin degradation was accompanied by medium alkalinization, the reduction of thiosulfate generated hydrogen sulfide gas, chitinase and manganese dependent peroxidase activity were not visually demonstrated within eight weeks, and keratinase activity was not evident at pH 8 within eight weeks. We demonstrate that all P. destructans isolates are capable of growth and sporulation on dead fish, insect, and mushroom tissues. Sole nitrogen source assays demonstrated that all P. destructans isolates exhibit Class 2 nitrogen utilization and that growth-dependent interactions occur among different pH and nitrogen sources. Substrate suitability assays demonstrated that all isolates could grow and sporulate on media ranging from pH 5–11 and tolerated media supplemented with 2000 mg/L of calcium and 700 mg/L of three separated sulfur compounds: thiosulfate L-cysteine, and sulfite. All isolates were intolerant to PEG-induced matric potential with delayed germination and growth at −2.5 MPa with no visible germination at −5 MPa. Interestingly, decreasing the surface tension with Tween 80 permitted germination and growth of P. destructans in −5 MPa PEG medium within 14

  5. Efecto biofungicida del gel de Aloe vera sobre Mycosphaerella fijiensis, agente causal de la Sigatoka negra en Musa (AAA

    Directory of Open Access Journals (Sweden)

    Edwin Jaramillo Aguilar

    2017-01-01

    Full Text Available El objetivo de este trabajo fue evaluar a nivel in vitro la actividad antifúngica del gel de Aloe vera sobre el crecimiento micelial de Mycosphaerella fijiensis. Se utilizó la técnica de envenenamiento en el medio de cultivo PDA para determinar la actividad antifúngica del gel. El diseño utilizado fue completamente al azar, con siete tratamientos y tres repeticiones. En los tratamientos se utilizó un fungicida químico comercial (propiconazol, a 250 ppm y 500 ppm; un biofungicida comercial (Trichoderma sp. a 500 ppm y 1000 ppm; ambos productos se usaron como testigo químico y biológico, respectivamente; el gel de Aloe vera a 500 ppm y 1000 ppm; y un testigo absoluto. Se determinó diferencias significativas entre los tratamientos (ANOVA, El test de Tukey demostró que todos los tratamientos registraron diferencia significativa (p ≤ 0,05 con respecto al testigo absoluto. El propiconazol presentó el mayor porcentaje de inhibición del micelio (73,10%; el test de Tukey y el porcentaje de inhibición del micelio presentaron valores similares en el control del crecimiento del hongo a los 30 días de inoculación, en los tratamientos gel de Aloe vera y el T6 de Trichoderma sp. Los resultados sugieren que el Aloe vera podría ser un adecuado biofungicida para el control de Mycosphaerella fijiensis, agente causal de la Sigatoka negra.

  6. Parasitosis intestinales en Argentina: principales agentes causales encontrados en la población y en el ambiente

    Directory of Open Access Journals (Sweden)

    María M Juárez

    Full Text Available Las parasitosis intestinales se encuentran ampliamente distribuidas en el mundo, con mayor prevalencia en los países en desarrollo. Principalmente afectan a los niños, en los que además provocan disminución del desarrollo físico y mental, situación que puede potenciarse enormemente cuando se suma a un estado nutricional deficiente. La Organización Mundial de la Salud las considera una de las principales causas de morbilidad, estrechamente ligada a la pobreza y relacionada con inadecuada higiene personal, incorrecta manipulación de los alimentos crudos, falta de servicios sanitarios, falta de provisión de agua potable y contaminación fecal del ambiente. Algunas enfermedades parasitarias se vinculan con condiciones de transmisión que existen universalmente, por lo que son cosmopolitas, mientras que otras tienen distribución geográfica variable. En los últimos años, debido a la globalización, el movimiento de personas de zonas endémicas a regiones no endémicas ha permitido la diseminación de ciertas parasitosis. Y aunque también influyen en la frecuencia de algunas de estas enfermedades las costumbres de los pueblos, las condiciones ambientales son un factor determinante para la supervivencia de los parásitos. En nuestro país, debido a la diversidad de suelos y condiciones climáticas que existen, es posible hallar variedad de agentes causales de estas parasitosis. El objetivo de este trabajo fue realizar una revisión bibliográfica de los agentes parasitarios causantes de enfermedades entéricas encontrados en la República Argentina, tanto en materia fecal de personas como en el ambiente, ya que la contaminación parasitaria de este último constituye un indicador directo del riesgo de infección por parásitos intestinales.

  7. Species of the Colletotrichum acutatum complex associated with anthracnose diseases of fruit in Brazil

    NARCIS (Netherlands)

    Bragança, Carlos A.D.; Damm, Ulrike; Baroncelli, Riccardo; Massola Júnior, Nelson S.; Crous, Pedro W.

    Abstract Although Colletotrichum acutatum was recently investigated and shown to be a species complex comprising about 30 species, the name is still used in its broad sense for anthracnose pathogens of fruits in Brazil. In this study, a multilocus molecular analysis was carried out based on a

  8. Survival of Colletotrichum acutatum in plant residue

    DEFF Research Database (Denmark)

    Parikka, Päivi; Lemmetty, A.; Sundelin, Thomas

    2016-01-01

    growing on the trial sites in Finland. The study showed that C. acutatum can survive in soil or on the soil surface in plant residue in Nordic conditions for nearly 3 years. Weeds can have infections of infested plant debris. In disease management, weed control and crop rotation for three years...... are important to control its spread to berry crops....

  9. Murcha do manjericão (Ocimum basilicum no Brasil: agente causal, círculo de plantas hospedeiras e transmissão via semente Sweet basil (Ocimum basilicum wilt in Brazil: causal agent, host range and seed transmission

    Directory of Open Access Journals (Sweden)

    Ailton Reis

    2007-06-01

    Full Text Available O manjericão (Ocimum basilicum L. é uma hortaliça da família Lamiaceae, utilizada na culinária ou como matéria prima para a indústria de fármacos e óleos essenciais. Amostras de plantas de manjericão apresentando sintomas de murcha, seca de hastes e podridão de colo foram coletadas na área rural de Brazlândia (DF durante a estação chuvosa de 2005. Outras duas amostras foram coletadas em plantas cultivadas em campo aberto e casas de vegetação na região de Ponte Alta (DF. Isolados de um fungo, identificado como Fusarium oxysporum, foram obtidos em todas as amostras. Testes de patogenicidade foram conduzidos com mudas das cultivares O. basilicum 'Dark Opal' e 'Italian Large Leaf', e de acessos das espécies O. americanum L. (manjericão de folha miúda, O. campechianum Mill. (alfavaca, Origanum manjorana L. (manjerona, Origanum vulgare L. (orégano, Mentha arvensis L. (menta, Coleus blumei Benth. (tapete, Leonorus sibiricus L. (rubim e Leonotis nepetaefolia (L. W.T. Aiton (cordão-de-frade. Todos os isolados fúngicos mostraram-se altamente virulentos sobre as duas cultivares de manjericão. Em O. campechianum e O. americanum os isolados causaram apenas suave escurecimento vascular e leve redução de crescimento, sendo avirulentos sobre acessos das espécies O. manjorana, O. vulgare, M. arvensis, C. blumei, L. sibiricus e L. nepetaefolia. Este conjunto de dados indicou que o agente causal da doença é o fungo F. oxysporum f. sp. basilici, constituindo-se no primeiro registro formal deste patógeno no Brasil. Os lotes de sementes utilizados nas áreas de ocorrência da doença foram submetidos a um teste de sanidade visando verificar a presença do patógeno. O fungo F. oxysporum f. sp. basilici foi detectado em quatro dos seis lotes e os isolados obtidos das sementes contaminadas mostraram similar sintomatologia e um idêntico perfil de virulência aos verificados em campo e casa de vegetação, sugerindo que as sementes

  10. Specific PCR detection of Fusarium oxysporum f. sp. raphani: a causal agent of Fusarium wilt on radish plants.

    Science.gov (United States)

    Kim, H; Hwang, S-M; Lee, J H; Oh, M; Han, J W; Choi, G J

    2017-08-01

    Fusarium oxysporum, a causal agent of Fusarium wilt, is one of the most important fungal pathogens worldwide, and detection of F. oxysporum DNA at the forma specialis level is crucial for disease diagnosis and control. In this study, two novel F. oxysporum f. sp. raphani (For)-specific primer sets were designed, FOR1-F/FOR1-R and FOR2-F/FOR2-R, to target FOQG_17868 and FOQG_17869 ORFs, respectively, which were selected based on the genome comparison of other formae speciales of F. oxysporum including conglutinans, cubense, lycopersici, melonis, and pisi. The primer sets FOR1-F/FOR1-R and FOR2-F/FOR2-R that amplified a 610- and 425-bp DNA fragment, respectively, were specific to For isolates which was confirmed using a total of 40 F. oxysporum isolates. From infected plants, the FOR2-F/FOR2-R primer set directly detected the DNA fragment of For isolates even when the radish plants were collected in their early stage of disease development. Although the loci targeted by the For-specific primer sets were not likely involved in the pathogenesis, the primer set FOR2-F/FOR2-R is available for the determination of pathogenicity of radish-infecting F. oxysporum isolates. This study is the first report providing novel primer sets to detect F. oxysporum f. sp. raphani. Because plant pathogenic Fusarium oxysporum has been classified into special forms based on its host specificity, identification of F. oxysporum usually requires a pathogenicity assay as well as knowledge of the morphological characteristics. For rapid and reliable diagnosis, this study provides PCR primer sets that specifically detect Fusarium oxysporum f. sp. raphani (For) which is a devastating pathogen of radish plants. Because one of the primer sets directly detected the DNA fragment of For isolates from infected plants, the specific PCR method demonstrated in this study will provide a foundation for integrated disease management practices in commodity crops. © 2017 The Society for Applied Microbiology.

  11. Characterization of Colletotrichum acutatum Causing Anthracnose of Anemone (Anemone coronaria L.)†

    Science.gov (United States)

    Freeman, Stanley; Shabi, Ezra; Katan, Talma

    2000-01-01

    Anthracnose, or leaf-curl disease of anemone, caused by Colletotrichum sp., has been reported to occur in Australia, western Europe, and Japan. Symptoms include tissue necrosis, corm rot, leaf crinkles, and characteristic spiral twisting of floral peduncles. Three epidemics of the disease have been recorded in Israel: in 1978, in 1990 to 1993, and in 1996 to 1998. We characterized 92 Colletotrichum isolates associated with anthracnose of anemone (Anemone coronaria L.) for vegetative compatibility (72 isolates) and for molecular genotype (92 isolates) and virulence (4 isolates). Eighty-six of the isolates represented the three epidemics in Israel, one isolate was from Australia, and five isolates originated from western Europe. We divided these isolates into three vegetative-compatibility groups (VCGs). One VCG (ANE-A) included all 10 isolates from the first and second epidemics, and 13 of 62 examined isolates from the third epidemic in Israel, along with the isolate from Australia and 4 of 5 isolates from Europe. Another VCG (ANE-F) included most of the examined isolates (49 of the 62) from the third epidemic, as well as Colletotrichum acutatum from strawberry, in Israel. Based on PCR amplification with species-specific primers, all of the anemone isolates were identified as C. acutatum. Anemone and strawberry isolates of the two VCGs were genotypically similar and indistinguishable when compared by arbitrarily primed PCR of genomic DNA. Only isolate NL-12 from The Netherlands, confirmed as C. acutatum but not compatible with either VCG, had a distinct genotype; this isolate represents a third VCG of C. acutatum. Isolates from anemone and strawberry could infect both plant species in artificial inoculations. VCG ANE-F was recovered from natural infections of both anemone and strawberry, but VCG ANE-A was recovered only from anemone. This study of C. acutatum from anemone illustrates the potential of VCG analysis to reveal distinct subspecific groups within a

  12. Role of the Colletotrichum acutatum sesquiterpene synthase CaTPS in the biosynthesis of sesquiterpenoids.

    Science.gov (United States)

    Buchvaldt Amby, Daniel; Manczak, Tom; Petersen, Mikael Agerlin; Sundelin, Thomas; Weitzel, Corinna; Grajewski, Maciej; Simonsen, Henrik Toft; Jensen, Birgit

    2016-10-01

    Colletotrichum acutatum is a major fungal pathogen of fruit crops, which causes severe yield losses in strawberry production. A potential key factor in plant-pathogen interactions is fungal sesquiterpenoids which have mycotoxic and phytotoxic activities. The first committed step in sesquiterpenoid biosynthesis is performed by sesquiterpene synthases (TPS). Only a few TPSs have been functionally characterized from filamentous fungi and none from the genus Colletotrichum. Despite being an important fungal pathogen to agriculture, it is poorly understood at the molecular and chemical levels. The terpenoid biochemistry in Coll. acutatum strain SA 0-1 was studied and one Coll. acutatum TPS (CaTPS) was successfully cloned and characterized in yeast. CaTPS catalyses the biosynthesis of multiple sesquiterpenoids. The two major products are β-caryophyllene and an unidentified sesquiterpenoid along with α-humulene as one of the minor sesquiterpenoid products. These products were also secreted by the fungus in strawberry fruit medium along with several other sesquiterpenoids indicating other TPSs are active during in vitro growth. β-Caryophyllene and α-humulene are known cytotoxic products important for ecological interactions and are produced by SA 0-1. Interestingly, a gene expression analysis using quantitative real-time PCR revealed a significant increase in expression of CaTPS during strawberry fruit infection, thus indicating that it could be involved in fruit infection. This is, we believe, the first characterization of TPS in Colletotrichum spp. and terpenoid profiles of Coll. acutatum, which could facilitate studies on the role of terpenoids in the ecology of Coll. acutatum.

  13. Role of the Colletotrichum acutatum sesquiterpene synthase CaTPS in the biosynthesis of sesquiterpenoids

    DEFF Research Database (Denmark)

    Amby, Daniel Buchvaldt; Manczak, Tom; Petersen, Mikael Agerlin

    2016-01-01

    biosynthesis is performed by sesquiterpene synthases (TPS). Only a few TPSs have been functionally characterized from filamentous fungi and none from the genus Colletotrichum. Despite being an important fungal pathogen to agriculture, it is poorly understood at the molecular and chemical levels. The terpenoid...... characterization of TPS in Colletotrichum spp. and terpenoid profiles of Coll. acutatum, which could facilitate studies on the role of terpenoids in the ecology of Coll. acutatum....

  14. A review of the Mycrocylus ulei Ascomycetes fungus, causative agent of South American rubber-leaf blight Revisión sobre el hongo Microcyclus ulei, agente causal del mal suramericano de la hoja del caucho

    OpenAIRE

    Ancízar Aristizábar Fabio; Montoya Castaño Dolly; García Romero Ibonne Aydee

    2006-01-01

    The Microcyclus ulei Ascomycetes fungus is the causal agent of south-American leaf blight (SALB), this being one of the most important diseases affecting the natural rubber tree (Hevea brasiliensis) in Latina-America and has been responsible for numerous economic losses. This fungus has presented high physiological variability, suggesting its great adaptability. HCN tolerance has been described as being one of the mechanisms associated with its virulence. Resistant Hevea clones have been obta...

  15. Causality in Classical Electrodynamics

    Science.gov (United States)

    Savage, Craig

    2012-01-01

    Causality in electrodynamics is a subject of some confusion, especially regarding the application of Faraday's law and the Ampere-Maxwell law. This has led to the suggestion that we should not teach students that electric and magnetic fields can cause each other, but rather focus on charges and currents as the causal agents. In this paper I argue…

  16. Reacción de variedades de frijol a la inoculación del nematodo Aphelenchoides besseyi, agente causal de la falsa mancha angular

    OpenAIRE

    Barrantes-Santamaría, Walter; Araya Fernández, Carlos Manuel

    2007-01-01

    Reacción de variedades de frijol a la inoculación artifi cial de Aphelenchoides besseyi, agente causal de la falsa mancha angular. Especímenes adultos y juveniles de A. besseyi provenientes de cultivo in vitro se inocularon sobre el follaje de plantas de frijol de las variedades Bribri, Huetar, Telire y Chirripó Rojo. Las edades de las plantas inoculadas en el invernadero fueron de diez, 20 y 30 días después de siembra (dds). Los bioensayos se realizaron en los invernaderos de la Escuela de C...

  17. BIOTRANSFORMATION OF FERULIC ACID BY THE PHYTOPATHOGENIC FUNGI Colletotrichum acutatum AND Lasiodiplodia theobromae

    Directory of Open Access Journals (Sweden)

    Manuel Alejandro Numpaque

    2016-01-01

    Full Text Available The microbial transformation of ferulic acid (FA offers a cleaner, more economical alternative for the natural production of flavorings and fragrances. In the present study, the biotransformation of FA using the filamentous phytopathogenic fungi Colletotrichum acutatum and Lasiodiplodia theobromae was researched. Initially, the toxicity of FA against both fungi was evaluated; the FA displayed a moderate toxicity (total inhibition at concentrations ≥ 2000 mg L-1 and apparently a detoxification mechanism was present. Afterwards, the microorganisms were incubated with the substrate at room conditions using a Czapek-Dox culture medium. The results demonstrated that the FA was mainly converted to 4-vinylguaiacol, reaching the highest abundance within the first 48 hours. To a lesser extent, acetovanillone, ethylguaiacol, and vanillin, among others, were produced. Interestingly, the compounds generated in the biotransformation of FA with C. acutatum and L. theobromae have been used as flavorings. Based on the identified metabolites, a possible metabolic pathway was proposed.

  18. Light quality influences the virulence and physiological responses of Colletotrichum acutatum causing anthracnose in pepper plants.

    Science.gov (United States)

    Yu, S-M; Ramkumar, G; Lee, Y H

    2013-08-01

    To explore the effects of light quality on the physiology and pathogenicity of Colletotrichum acutatum, we analysed the morphological traits, melanin production and virulence of the pathogen under different light wavelengths. The influence of light wavelength on the mycelial growth and conidial germination of C. acutatum was investigated using red, green, blue and white light sources. Red and green light reduced the mycelial growth in comparison with blue and white light, and dark conditions. The least percentage of conidial germination was observed under blue light, while the germination rate among white, red and green light, as well as in the dark, was insignificant. In comparison with its influence on mycelial growth and conidial germination, light wavelength significantly affected the pathogen's virulence towards hot pepper fruits. The highest disease severity was observed under blue light, which was at least a twofold increase compared with the disease severity under other light conditions. To elucidate the effect of light on the disparity in virulence, scytalone was assayed by HPLC, and scd1 gene expression was examined with real-time PCR. The highest and lowest scytalone production was observed in the cultures incubated under blue (10.9 mAU) and green light (1.5 mAU), respectively. Higher scd1 gene expression (~ 40-fold increase) was observed in cultures incubated under blue and white light in comparison with those incubated in the dark. This study revealed that light affects the growth, colonial morphology and virulence of C. acutatum. The pathogen needs light for its active melanin production and also to attain higher virulence. This is the first report on the effect of light quality on the virulence of C. acutatum. The findings of this study will broaden our knowledge of the influence of light on physiological responses of fungal pathogens. © 2013 The Society for Applied Microbiology.

  19. Epidemiology of colletotrichum acutatum, cause of anthracnose on highbush blueberry, in British Columbia

    OpenAIRE

    Verma,Nitin

    2005-01-01

    Blueberry anthracnose reduces yield and post-harvest quality of blueberries in British Columbia. Isolates recovered from diseased fruit during 2002-2004 were identified as Colletotrichum acutatum using colony morphology, growth rate, and PCR. Leaf-wetness and temperature data indicated that plants exposed to prevailing environmental field conditions and natural inoculum in 2001-2003 required 10 hr of leaf wetness at 1 1•‹C for successful fruit infection. Three peaks of infection occurred; at ...

  20. A novel fungal hyperparasite of Puccinia striiformis f. sp. tritici, the causal agent of wheat stripe rust.

    Directory of Open Access Journals (Sweden)

    Gangming Zhan

    Full Text Available Puccinia striiformis f. sp. tritici (Pst, the causal fungus of wheat stripe rust, was previously reported to be infected by Lecanicillium lecanii, Microdochium nivale and Typhula idahoensis. Here, we report a novel hyperparasite on Pst. This hyperparasitic fungus was identified as Cladosporium cladosporioides (Fresen. GA de Vries based on morphological characteristics observed by light and scanning electron microscopy together with molecular data. The hyperparasite reduced the production and viability of urediniospores and, therefore, could potentially be used for biological control of wheat stripe rust.

  1. Effect of temperature and photoperiod on the in vitro germination of conidia of Botrytis squamosa, the causal agent of Botrytis leaf blight of onion

    Directory of Open Access Journals (Sweden)

    Leandro Luiz Marcuzzo

    Full Text Available ABSTRACT Temperature and photoperiod have a direct effect on spore germination and, for Botrytis squamosa, there is scare information on this subject. Learning the biology of the causal agent has a great importance to understand the development of the disease in the field, as well to take control measures. With the aim of evaluating the influence of temperature and photoperiod on B. squamosa conidial germination, an experiment was conducted in a completely randomized design with four replicates. A 0.1-ml suspension of 1.65x105 conidia per ml was added and spread on Petri dishes containing 1% water-agar. The Petri dishes were placed in BOD incubators adjusted to 10, 15, 20, 25 and 30°C without light, and the percentage of germination of 100 conidia was evaluated under an optical microscope by measuring the germ tube after 24 hours of incubation. In a second moment, this experiment was repeated by incubating the spores at 23°C and photoperiods of 0, 6, 12, 18 and 24 hours, and by evaluating the percentage of germination after 24 hours. Results showed that the highest germination percentages can be obtained in the temperature range between 10 (79.75% and 30°C (92.5%, and the optimum temperature for germination is 23°C. In relation to photoperiod, the highest germination percentage (94% was obtained without light, which indicates that B. squamosa germination is favored by shorter periods of light. Thus, the information obtained on the biology of the causal agent of botrytis leaf blight allows better understand the epidemiology of this disease, and such results can be used to help develop a disease forecasting system.

  2. Effects of Essential Oils from Thyme, Cinnamon and Clove on Mycelial Growth of Colletotrichum acutatum

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    Nataša Duduk

    2010-01-01

    Full Text Available Effects of the volatile phase of thyme, cinnamon and clove essential oils onColletotrichum acutatum were investigated. Mycelial disc was placed in the center of thePetri dish (V=66 ml containing PDA. Different volumes of either non- or ethanol-dilutedessential oils were placed on the inner side of the dish cover to obtain final concentrationsof 153, 107, 76, 46, 15, 14, 12, 11, 7.6, 3.82, 1.53, 0.153 and 0.0153 μl/L of air. The dishes were sealed with Parafilm and incubated in up-side-down position. After 7 days of incubation,mycelial growth was recorded by measuring the colony diameter. If no mycelial growthwas recorded, the disc was transferred to a new PDA plate in order to evaluate whetherthe activity was either fungistatic or fungicidal. Mean growth values were obtained andthen converted to inhibition percentage of mycelial growth compared with the controltreatment. All the tested essential oils inhibited mycelial growth of C. acutatum in the dosedependent manner. Mycelial growth was totally inhibited by thyme oil in the concentrationof 76 μl/L of air. The same results were obtained by cinnamon and clove oil in the concentrationof 107 μl/L of air. Thyme and cinnamon oil had fungicidal effect in concentrationsof 107 and 153 μl/L respectively. The results obtained provide evidence on the antifungalin vitro effect of the tested essential oils as potential means for the control of C. acutatum.

  3. Isolation and Characterization of the Colletotrichum acutatum ABC Transporter CaABC1

    Directory of Open Access Journals (Sweden)

    Suyoung Kim

    2014-12-01

    Full Text Available Fungi tolerate exposure to various abiotic stresses, including cytotoxic compounds and fungicides, via their ATP-driven efflux pumps belonging to ATP-binding cassette (ABC transporters. To clarify the molecular basis of interaction between the fungus and various abiotic stresses including fungicides, we constructed a cDNA library from germinated conidia of Colletotrichum acutatum, a major anthracnose pathogen of pepper (Capsicum annum L.. Over 1,000 cDNA clones were sequenced, of which single clone exhibited significant nucleotide sequence homology to ABC transporter genes. We isolated three fosmid clones containing the C. acutatum ABC1 (CaABC1 gene in full-length from genomic DNA library screening. The CaABC1 gene consists of 4,059 bp transcript, predicting a 1,353-aa protein. The gene contains the typical ABC signature and Walker A and B motifs. The 5′-flanking region contains a CAAT motif, a TATA box, and a Kozak region. Phylogenetic and structural analysis suggested that the CaABC1 is a typical ABC transporter gene highly conserved in various fungal species, as well as in Chromista, Metazoans, and Viridiplantae. We also found that CaABC1 was up-regulated during conidiation and a minimal medium condition. Moreover, CaABC1 was induced in iprobenfos, kresoxim-methyl, thiophanate-methyl, and hygromycin B. These results demonstrate that CaABC1 is necessary for conidiation, abiotic stress, and various fungicide resistances. These results will provide the basis for further study on the function of ABC transporter genes in C. acutatum.

  4. Isolation and Characterization of the Colletotrichum acutatum ABC Transporter CaABC1.

    Science.gov (United States)

    Kim, Suyoung; Park, Sook-Young; Kim, Hyejeong; Kim, Dongyoung; Lee, Seon-Woo; Kim, Heung Tae; Lee, Jong-Hwan; Choi, Woobong

    2014-12-01

    Fungi tolerate exposure to various abiotic stresses, including cytotoxic compounds and fungicides, via their ATP-driven efflux pumps belonging to ATP-binding cassette (ABC) transporters. To clarify the molecular basis of interaction between the fungus and various abiotic stresses including fungicides, we constructed a cDNA library from germinated conidia of Colletotrichum acutatum, a major anthracnose pathogen of pepper (Capsicum annum L.). Over 1,000 cDNA clones were sequenced, of which single clone exhibited significant nucleotide sequence homology to ABC transporter genes. We isolated three fosmid clones containing the C. acutatum ABC1 (CaABC1) gene in full-length from genomic DNA library screening. The CaABC1 gene consists of 4,059 bp transcript, predicting a 1,353-aa protein. The gene contains the typical ABC signature and Walker A and B motifs. The 5'-flanking region contains a CAAT motif, a TATA box, and a Kozak region. Phylogenetic and structural analysis suggested that the CaABC1 is a typical ABC transporter gene highly conserved in various fungal species, as well as in Chromista, Metazoans, and Viridiplantae. We also found that CaABC1 was up-regulated during conidiation and a minimal medium condition. Moreover, CaABC1 was induced in iprobenfos, kresoxim-methyl, thiophanate-methyl, and hygromycin B. These results demonstrate that CaABC1 is necessary for conidiation, abiotic stress, and various fungicide resistances. These results will provide the basis for further study on the function of ABC transporter genes in C. acutatum.

  5. Elucidation of the disease cycle of olive anthracnose caused by Colletotrichum acutatum.

    Science.gov (United States)

    Moral, Juan; de Oliveira, Rodrígues; Trapero, Antonio

    2009-05-01

    Anthracnose, caused by Colletotrichum acutatum and C. gloeosporioides, is a major fungal disease of olive in many countries. In Spain, the disease has been associated only with a characteristic rot and mummification of mature fruit. The purpose of this study was to determine whether C. acutatum could infect other plant tissues that may serve as sources of inoculum for anthracnose epidemics. Inoculations of young plants or detached leaves and field observations demonstrated that flowers and immature olive fruit are susceptible to the pathogen. Flower infection caused blight of inflorescences and infection of developing fruit. Immature fruit were infected in all phenological stages, although infection remained latent for 7 to 8 months, until the onset of fruit ripening. Fruit susceptibility increased and latent period decreased with maturity. Fruit were required for symptom development on inoculated plants. Plants without fruit were infected but they did not show any disease symptoms. Only plants with rotten fruit developed leaf wilting and branch dieback symptoms several weeks later. These results, together with the low level of pathogen isolation from affected leaves and branches and the toxicity of sterile fungal extracts to olive cuttings, suggest that a toxic substance produced by C. acutatum in rotten fruit may account for this syndrome. Both disease syndromes, fruit rot and branch dieback, developed in several olive cultivars, which were equally susceptible to the pathogen. However, olive cultivars differed in their response to flower and fruit infection. Latent infection of developing fruit during the spring may permit survival of the pathogen during the hot and dry summer and serve as an inoculum source for anthracnose epidemics that develop on ripening fruit in autumn.

  6. Cladosporium cladosporioides and Cladosporium pseudocladosporioides as potential new fungal antagonists of Puccinia horiana Henn., the causal agent of chrysanthemum white rust.

    Directory of Open Access Journals (Sweden)

    David Eduardo Torres

    Full Text Available Puccinia horiana Hennings, the causal agent of chrysanthemum white rust, is a worldwide quarantine organism and one of the most important fungal pathogens of Chrysanthemum × morifolium cultivars, which are used for cut flowers and as potted plants in commercial production regions of the world. It was previously reported to be controlled by Lecanicillium lecanii, Cladosporium sphaerospermum, C. uredinicola and Aphanocladium album, due to their antagonistic and hyperparasitic effects. We report novel antagonist species on Puccinia horiana. Fungi isolated from rust pustules in a commercial greenhouse from Villa Guerrero, México, were identified as Cladosporium cladosporioides and Cladosporium pseudocladosporioides based upon molecular analysis and morphological characters. The antagonism of C. cladosporioides and C. pseudocladosporioides on chrysanthemum white rust was studied using light and electron microscopy in vitro at the host/parasite interface. Cladosporium cladosporioides and C. pseudocladosporioides grew towards the white rust teliospores and colonized the sporogenous cells, but no direct penetration of teliospores was observed; however, the structure and cytoplasm of teliospores were altered. The two Cladosporium spp. were able to grow on media containing laminarin, but not when chitin was used as the sole carbon source; these results suggest that they are able to produce glucanases. Results from the study indicate that both Cladosporium species had potential as biological control agents of chrysanthemum white rust.

  7. Cladosporium cladosporioides and Cladosporium pseudocladosporioides as potential new fungal antagonists of Puccinia horiana Henn., the causal agent of chrysanthemum white rust.

    Science.gov (United States)

    Torres, David Eduardo; Rojas-Martínez, Reyna Isabel; Zavaleta-Mejía, Emma; Guevara-Fefer, Patricia; Márquez-Guzmán, G Judith; Pérez-Martínez, Carolina

    2017-01-01

    Puccinia horiana Hennings, the causal agent of chrysanthemum white rust, is a worldwide quarantine organism and one of the most important fungal pathogens of Chrysanthemum × morifolium cultivars, which are used for cut flowers and as potted plants in commercial production regions of the world. It was previously reported to be controlled by Lecanicillium lecanii, Cladosporium sphaerospermum, C. uredinicola and Aphanocladium album, due to their antagonistic and hyperparasitic effects. We report novel antagonist species on Puccinia horiana. Fungi isolated from rust pustules in a commercial greenhouse from Villa Guerrero, México, were identified as Cladosporium cladosporioides and Cladosporium pseudocladosporioides based upon molecular analysis and morphological characters. The antagonism of C. cladosporioides and C. pseudocladosporioides on chrysanthemum white rust was studied using light and electron microscopy in vitro at the host/parasite interface. Cladosporium cladosporioides and C. pseudocladosporioides grew towards the white rust teliospores and colonized the sporogenous cells, but no direct penetration of teliospores was observed; however, the structure and cytoplasm of teliospores were altered. The two Cladosporium spp. were able to grow on media containing laminarin, but not when chitin was used as the sole carbon source; these results suggest that they are able to produce glucanases. Results from the study indicate that both Cladosporium species had potential as biological control agents of chrysanthemum white rust.

  8. Effect of Two Biological Formulations Based on Bacillus subtilis and Pseudomonas fluorescens on Control of Didymella applanata, the Causal Agent of Red Raspberry Cane Spur Blight

    Directory of Open Access Journals (Sweden)

    Margarita Shternshis

    2016-01-01

    Full Text Available In vitro and in vivo studies were conducted to estimate the efficacy of the two microbial formulations based on Bacillus subtilis Cohn. and Pseudomonas fluorescens Mig. on the fungus Didymella applanata (Niessl. Sacc., the causal agent of red raspberry (Rubus idaeus L. spur blight. In vitro, both bacteria reduced the growth of D. applanata. In inoculation experiments with raspberry canes in two cultivars with different susceptibility to D. applanata, these antagonistic bacteria suppressed fungal development by reducing the lesions area and the number of D. applanata fruiting bodies. Field trials of two biological formulations under natural conditions showed a significant suppression of the disease. B. subtilis and P. fluorescens included in the formulations revealed antagonistic activity towards D. applanata that depended on the red raspberry cultivar and weather conditions. In all cases, B. subtilis showed better results than P. fluorescens in biocontrol of the raspberry spur blight. This study demonstrated for the first time the ability of the biocontrol agents B. subtilis and P. fluorescens to suppress red raspberry cane spur blight, a serious worldwide disease.

  9. Diversity of endophytic fungal community of cacao (Theobroma cacao L.) and biological control of Crinipellis perniciosa, causal agent of Witches' Broom Disease.

    Science.gov (United States)

    Rubini, Marciano R; Silva-Ribeiro, Rute T; Pomella, Alan W V; Maki, Cristina S; Araújo, Welington L; Dos Santos, Deise R; Azevedo, João L

    2005-01-01

    The basidiomycete fungus Crinipellis perniciosa (Stahel) Singer is the causal agent of Witches' Broom Disease of Cacao (Theobromacacao L.) which is the main factor limiting cacao production in the Americas. Pod losses of up to 90% are experienced in affected areas as evidenced by the 50% drop in production in Bahia province, Brazil following the arrival of the C. perniciosa in the area in 1989. The disease has proven particularly difficult to control and many farmers in affected areas have given up cacao cultivation. In order to evaluate the potential of endophytes as a biological control agent of this phytopathogen, the endophytic fungal community of resistant and susceptible cacao plants as well as affected branches was studied between 2001 and 2002. The fungal community was identified by morphological traits and rDNA sequencing as belonging to the genera Acremonium, Blastomyces, Botryosphaeria, Cladosporium, Colletotrichum, Cordyceps, Diaporthe, Fusarium, Geotrichum, Gibberella, Gliocladium, Lasiodiplodia, Monilochoetes, Nectria, Pestalotiopsis, Phomopsis, Pleurotus, Pseudofusarium, Rhizopycnis, Syncephalastrum, Trichoderma, Verticillium and Xylaria. These fungi were evaluated both in vitro and in vivo by their ability to inhibit C. perniciosa. Among these, some were identified as potential antagonists, but only one fungus (Gliocladium catenulatum) reduced the incidence of Witches' Broom Disease in cacao seedlings to 70%.

  10. Causal universe

    CERN Document Server

    Ellis, George FR; Pabjan, Tadeusz

    2013-01-01

    Written by philosophers, cosmologists, and physicists, this collection of essays deals with causality, which is a core issue for both science and philosophy. Readers will learn about different types of causality in complex systems and about new perspectives on this issue based on physical and cosmological considerations. In addition, the book includes essays pertaining to the problem of causality in ancient Greek philosophy, and to the problem of God's relation to the causal structures of nature viewed in the light of contemporary physics and cosmology.

  11. Causal Agents of Mycobacterial Diseases in Freshwater Ornamental Fish and their Importance for Human Health in the Czech Republic

    Directory of Open Access Journals (Sweden)

    J. Řehulka

    2006-01-01

    Full Text Available In the period from 1995 to 2004, the following mycobacterial species were isolated during the examination of the state of health of aquarium fish from the Moravian-Silesian region of the Czech Republic: Mycobacterium fortuitum (Paracheirodon axelrodi, Poecilia sphenops, Hemigrammus rhodostomus, Hyphessobrycon flammeus, M. chelonae (P. axelrodi, Betta splendens, Xiphophorus helleri, Puntius tetrazona, M. kansasii (P. axelrodi, B. splendens, M. simiae (Hyphessobrycon ecuadoriensis, and M. gordonae (P. axelrodi, Colisa lalia, B. splendens, Symphysodon discus. The first isolation from aquarium fish was recorded in the case of M. kansasii and the second isolation in the case of M. simiae; both should also be taken into account as aetiological agents of mycobacterial infections in humans. The measures to reduce mycobacterial infections in both fish and humans should include monitoring water mains as possible sources of M. kansasii infections, compliance with the sanitation principles in handling fish suspected of being infected and the content of tanks (molluscs, water, plants, and the introduction of strict veterinary inspection of imported fish, fish from aquarist shops and from large-scale distributors.

  12. The Colletotrichum acutatum Species Complex as a Model System to Study Evolution and Host Specialization in Plant Pathogens

    Science.gov (United States)

    Baroncelli, Riccardo; Talhinhas, Pedro; Pensec, Flora; Sukno, Serenella A.; Le Floch, Gaetan; Thon, Michael R.

    2017-01-01

    Colletotrichum spp. infect a wide diversity of hosts, causing plant diseases on many economically important crops worldwide. The genus contains approximately 189 species organized into at least 11 major phylogenetic lineages, also known as species complexes. The Colletotrichum acutatum species complex is a diverse yet relatively closely related group of plant pathogenic fungi within this genus. Within the species complex we find a wide diversity of important traits such as host range and host preference, mode of reproduction and differences in the strategy used to infect their hosts. Research on fungal comparative genomics have attempted to find correlations in these traits and patterns of gene family evolution but such studies typically compare fungi from different genera or even different fungal Orders. The C. acutatum species complex contains most of this diversity within a group of relatively closely related species. This Perspective article presents a review of the current knowledge on C. acutatum phylogeny, biology, and pathology. It also demonstrates the suitability of C. acutatum for the study of gene family evolution on a fine scale to uncover evolutionary events in the genome that are associated with the evolution of phenotypic characters important for host interactions. PMID:29075253

  13. A revision of the history of the Colletotrichum acutatum species complex in the Nordic countries based on herbarium specimens

    DEFF Research Database (Denmark)

    Sundelin, Thomas; Strømeng, Gunn Mari; Gjærum, Halvor B.

    2015-01-01

    and Denmark before the first confirmed findings of C. acutatum complex members in this region. Sequencing parts of the fungal ITS regions showed that members of the species complex were present in 13 of the 21 specimens collected in different parts of Norway and Denmark between 1948 and 1991, representing...

  14. The Colletotrichum acutatum Species Complex as a Model System to Study Evolution and Host Specialization in Plant Pathogens

    Directory of Open Access Journals (Sweden)

    Riccardo Baroncelli

    2017-10-01

    Full Text Available Colletotrichum spp. infect a wide diversity of hosts, causing plant diseases on many economically important crops worldwide. The genus contains approximately 189 species organized into at least 11 major phylogenetic lineages, also known as species complexes. The Colletotrichum acutatum species complex is a diverse yet relatively closely related group of plant pathogenic fungi within this genus. Within the species complex we find a wide diversity of important traits such as host range and host preference, mode of reproduction and differences in the strategy used to infect their hosts. Research on fungal comparative genomics have attempted to find correlations in these traits and patterns of gene family evolution but such studies typically compare fungi from different genera or even different fungal Orders. The C. acutatum species complex contains most of this diversity within a group of relatively closely related species. This Perspective article presents a review of the current knowledge on C. acutatum phylogeny, biology, and pathology. It also demonstrates the suitability of C. acutatum for the study of gene family evolution on a fine scale to uncover evolutionary events in the genome that are associated with the evolution of phenotypic characters important for host interactions.

  15. Causal and causally separable processes

    Science.gov (United States)

    Oreshkov, Ognyan; Giarmatzi, Christina

    2016-09-01

    The idea that events are equipped with a partial causal order is central to our understanding of physics in the tested regimes: given two pointlike events A and B, either A is in the causal past of B, B is in the causal past of A, or A and B are space-like separated. Operationally, the meaning of these order relations corresponds to constraints on the possible correlations between experiments performed in the vicinities of the respective events: if A is in the causal past of B, an experimenter at A could signal to an experimenter at B but not the other way around, while if A and B are space-like separated, no signaling is possible in either direction. In the context of a concrete physical theory, the correlations compatible with a given causal configuration may obey further constraints. For instance, space-like correlations in quantum mechanics arise from local measurements on joint quantum states, while time-like correlations are established via quantum channels. Similarly to other variables, however, the causal order of a set of events could be random, and little is understood about the constraints that causality implies in this case. A main difficulty concerns the fact that the order of events can now generally depend on the operations performed at the locations of these events, since, for instance, an operation at A could influence the order in which B and C occur in A’s future. So far, no formal theory of causality compatible with such dynamical causal order has been developed. Apart from being of fundamental interest in the context of inferring causal relations, such a theory is imperative for understanding recent suggestions that the causal order of events in quantum mechanics can be indefinite. Here, we develop such a theory in the general multipartite case. Starting from a background-independent definition of causality, we derive an iteratively formulated canonical decomposition of multipartite causal correlations. For a fixed number of settings and

  16. Producción in vitro de pectinasas por Colletotrichum acutatum

    Directory of Open Access Journals (Sweden)

    Patiño Torres Carlos

    2010-03-01

    Full Text Available Los hongos del género Colletotrichum son reconocidos productores de sustancias fifitotóxicas de bajo peso molecular y de enzimas que juegan papeles clave en su interacción patogénica con varios cultivos. Este estudio tuvo como objetivo determinar la naturaleza de las sustancias fitotóxicas producidas por C. acutatum en los medios de cultivo líquido Czapeck-Dox, Fries y MS, que estuviesen implicados en su interacción patogénica con el tomate de árbol (Solanum betaceae. Los procedimientos y resultados de la evaluación permitieron descartar que la actividad fitotóxica observada sobre los frutos de tomate inoculados con los extractos de los medios de cultivo se debiera a metabolitos de bajo peso molecular. Por el contrario, utilizando la prueba de placa de pozos (Dingle et al., 1953 se estableció que C. acutatum produce en los medios de cultivo evaluados enzimas con actividad pectinasa, tanto liasas como hidrolasas, las cuales podrían estar implicadas en la enfermedad de la antracnosis del tomate de árbol. Los resultados demostraron además que la producción de las enzimas se ve influenciada por el pH del medio de cultivo.

  17. Producción in vitro de pectinasas por Colletotrichum acutatum

    Directory of Open Access Journals (Sweden)

    Carlos Patiño Torres

    2010-01-01

    Full Text Available Los hongos del género Colletotrichum son reconocidos productores de sustancias fifitotóxicas de bajo peso molecular y de enzimas que juegan papeles clave en su interacción patogénica con varios cultivos. Este estudio tuvo como objetivo determinar la naturaleza de las sustancias fitotóxicas producidas por C. acutatum en los medios de cultivo líquido Czapeck-Dox, Fries y MS, que estuviesen implicados en su interacción patogénica con el tomate de árbol (Solanum betaceae. Los procedimientos y resultados de la evaluación permitieron descartar que la actividad fitotóxica observada sobre los frutos de tomate inoculados con los extractos de los medios de cultivo se debiera a metabolitos de bajo peso molecular. Por el contrario, utilizando la prueba de placa de pozos (Dingle et al., 1953 se estableció que C. acutatum produce en los medios de cultivo evaluados enzimas con actividad pectinasa, tanto liasas como hidrolasas, las cuales podrían estar implicadas en la enfermedad de la antracnosis del tomate de árbol. Los resultados demostraron además que la producción de las enzimas se ve influenciada por el pH del medio de cultivo.

  18. Species of the Colletotrichum acutatum complex associated with anthracnose diseases of fruit in Brazil.

    Science.gov (United States)

    Bragança, Carlos A D; Damm, Ulrike; Baroncelli, Riccardo; Massola Júnior, Nelson S; Crous, Pedro W

    2016-04-01

    Although Colletotrichum acutatum was recently investigated and shown to be a species complex comprising about 30 species, the name is still used in its broad sense for anthracnose pathogens of fruits in Brazil. In this study, a multilocus molecular analysis was carried out based on a dataset of ITS, HIS3, GAPDH, CHS-1, TUB2 and ACT sequences of Colletotrichum strains belonging to the C. acutatum species complex from fruits collected in different regions in Brazil combined with sequences of ex-type and other reference strains of species belonging to this complex. The strains were revealed to belong to Colletotrichum nymphaeae, Colletotrichum melonis, Colletotrichum abscissum and one new species, namely Colletotrichum paranaense, from apple and peach. Morphological descriptions of the new species and a strain closely related to but diverging from C. melonis are provided. From the data presently available, the most common species on apple fruits in Brazil is C. nymphaeae. In a pathogenicity test, strains of all four species caused lesions on detached apple, peach and guava fruits, except for strain CBS 134730 that did not infect guava fruits. Copyright © 2016 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

  19. Causal mapping

    DEFF Research Database (Denmark)

    Rasmussen, Lauge Baungaard

    2006-01-01

    The lecture note explains how to use the causal mapping method as well as the theoretical framework aoosciated to the method......The lecture note explains how to use the causal mapping method as well as the theoretical framework aoosciated to the method...

  20. Partial characterization of bacteriocin-like compounds from two strains of Bacillus cereus with biological activity against Paenibacillus larvae, the causal agent of American Foulbrood disease.

    Science.gov (United States)

    Minnaard, J; Alippi, A M

    2016-12-01

    American Foulbrood (AFB), caused by the spore-forming Gram-positive bacterium Paenibacillus larvae, is the most severe bacterial disease affecting honeybees worldwide. Two bacterial isolates showing specific inhibitory activity against P. larvae were identified as Bacillus cereus by 16S rDNA sequencing. Antagonistic compounds were obtained from cell-free supernatants of strains m6c and m387 growing on Trypticase Soy Broth and concentrated by NH4 SO4 precipitation, ultrafiltration and butanol extraction. Both compounds were characterized as bacteriocin-like inhibitory substances (BLIS). BLISm6c and BLISm387 were stable at 70°C for 30 min and active in the pH range from 3 to 7. The antibacterial activity was completely lost at pH values higher than 8 or temperatures >80°C. Both BLIS have a narrow activity range and highly inhibit the growth of P. larvae. BLISm6c and BLISm387 differ from each other and other BLIS reportedly produced by B. cereus with regard to their molecular weights, antibacterial activity, minimal inhibitory concentration values and sensitivity to degradative enzymes. The findings of this study suggest that BLISm6c and BLISm387 can potentially be used to control AFB. An Integrated Pest Management (IPM) approach is needed to ensure the sustainability of the beekeeping industry due to the increasing demand for organic honey and the reduction of dependence on antibiotics. Biocontrol agents produced by bacteria isolated from apiarian sources seem promising and able to combine with an IPM strategy. The most significant findings of this study are the characterization of bacteriocin-like compounds (BLIS) obtained from two strains of Bacillus cereus isolated from honey. Both BLIS have a narrow activity range and highly inhibit the growth of Paenibacillus larvae, the causal agent of American Foulbrood disease of honey bees. © 2016 The Society for Applied Microbiology.

  1. Transmission of Pantoea ananatis and P. agglomerans, causal agents of center rot of onion (Allium cepa), by onion thrips (Thrips tabaci) through feces.

    Science.gov (United States)

    Dutta, B; Barman, A K; Srinivasan, R; Avci, U; Ullman, D E; Langston, D B; Gitaitis, R D

    2014-08-01

    Frankliniella fusca, the tobacco thrips, has been shown to acquire and transmit Pantoea ananatis, one of the causal agents of the center rot of onion. Although Thrips tabaci, the onion thrips, is a common pest of onions, its role as a vector of P. ananatis has been unknown. The bacterium, P. agglomerans, is also associated with the center rot of onion, but its transmission by thrips has not been previously investigated. In this study, we investigated the relationship of T. tabaci with P. ananatis and P. agglomerans. Surface-sterilized T. tabaci were provided with various acquisition access periods (AAP) on onion leaves inoculated with either P. ananatis or P. agglomerans. A positive exponential relationship was observed between thrips AAP duration and P. ananatis (R² = 0.967; P = 0.023) or P. agglomerans acquisition (R² = 0.958; P = 0.017). Transmission experiments conducted with T. tabaci adults indicated that 70% of the seedlings developed center rot symptoms 15 days after inoculation. Immunofluorescence microscopy with antibodies specific to P. ananatis revealed that the bacterium was localized only in the gut of T. tabaci adults. Mechanical inoculation of onion seedlings with fecal rinsates alone produced center rot but not with salivary secretions. Together these results suggested that T. tabaci could efficiently transmit P. ananatis and P. agglomerans.

  2. Multiple locus VNTR analysis highlights that geographical clustering and distribution of Dichelobacter nodosus, the causal agent of footrot in sheep, correlates with inter-country movements.

    Science.gov (United States)

    Russell, Claire L; Smith, Edward M; Calvo-Bado, Leonides A; Green, Laura E; Wellington, Elizabeth M H; Medley, Graham F; Moore, Lynda J; Grogono-Thomas, Rosemary

    2014-03-01

    Dichelobacter nodosus is a Gram-negative, anaerobic bacterium and the causal agent of footrot in sheep. Multiple locus variable number tandem repeat (VNTR) analysis (MLVA) is a portable technique that involves the identification and enumeration of polymorphic tandem repeats across the genome. The aims of this study were to develop an MLVA scheme for D. nodosus suitable for use as a molecular typing tool, and to apply it to a global collection of isolates. Seventy-seven isolates selected from regions with a long history of footrot (GB, Australia) and regions where footrot has recently been reported (India, Scandinavia), were characterised. From an initial 61 potential VNTR regions, four loci were identified as usable and in combination had the attributes required of a typing method for use in bacterial epidemiology: high discriminatory power (D>0.95), typeability and reproducibility. Results from the analysis indicate that D. nodosus appears to have evolved via recombinational exchanges and clonal diversification. This has resulted in some clonal complexes that contain isolates from multiple countries and continents; and others that contain isolates from a single geographic location (country or region). The distribution of alleles between countries matches historical accounts of sheep movements, suggesting that the MLVA technique is sufficiently specific and sensitive for an epidemiological investigation of the global distribution of D. nodosus. Copyright © 2013 The Authors. Published by Elsevier B.V. All rights reserved.

  3. Post-transcriptional silencing of the SGE1 gene induced by a dsRNA hairpin in Fusarium oxysporum f. sp cubense, the causal agent of Panama disease.

    Science.gov (United States)

    Fernandes, J S; Angelo, P C S; Cruz, J C; Santos, J M M; Sousa, N R; Silva, G F

    2016-04-04

    Fusarium oxysporum f. sp cubense (Foc), the causal agent of Panama disease, is responsible for economic losses in banana crops worldwide. The identification of genes that effectively act on pathogenicity and/or virulence may contribute to the development of different strategies for disease control and the production of resistant plants. The objective of the current study was to analyze the importance of SGE1 gene expression in Foc virulence through post-transcriptional silencing using a double-stranded RNA hairpin. Thirteen transformants were selected based on different morphological characteristics, and sporulation in these transformants was significantly reduced by approximately 95% (P < 0.05) compared to that of the wild-type strain. The relative SGE1 expression levels in the transformant strains were reduced by 27 to 47% compared to those in the wild-type strain. A pathogenicity analysis revealed that the transformants were able to reach the rhizomes and pseudostems of the inoculated banana plants. However, the transformants induced initial disease symptoms in the banana plants approximately 10 days later than that by the wild-type Foc, and initial disease symptoms persisted even at 45 days after inoculation. These results indicate that the SGE1 gene is directly involved in the virulence of Foc. Therefore, SGE1 may be a potential candidate for host-induced gene silencing in banana plants.

  4. Genetic and morphological evidence that Phoma sclerotioides, causal agent of brown root rot of alfalfa, is composed of a species complex.

    Science.gov (United States)

    Wunsch, Michael J; Bergstrom, Gary C

    2011-05-01

    Phoma sclerotioides, causal agent of brown root rot of alfalfa, causes severe root and crown lesions on alfalfa and other perennial forage legumes in regions with harsh winters. Isolates of P. sclerotioides exhibit diverse cultural morphologies on potato dextrose agar (PDA), suggesting that they may exhibit a high degree of genetic diversity. To investigate the genetic relatedness of P. sclerotioides isolates, 154 isolates from North America were sequenced at 10 loci. Maximum parsimony and maximum likelihood analyses of the complete 10-locus data set placed isolates into multiple strongly supported clades, and analyses of gene-jackknife and single-gene partitions of the data set indicated robust support for six major clades and three subclades. Genetic differences corresponded closely to differences in conidial size and septation, pycnidial neck length, mycelial pigmentation, and growth rate in axenic culture at 18 and 25°C. Isolates exhibited morphologies broadly consistent with the species description of P. sclerotioides, and new species were not designated. On the basis of genetic and morphological differences, we propose establishing seven infraspecific varieties within P. sclerotioides: P. sclerotioides var. sclerotioides, champlainii, viridis, obscurus, steubenii, macrospora, and saskatchewanii. All varieties of P. sclerotioides caused brown root rot of alfalfa and grew well at low temperatures.

  5. In vitro antibacterial effect of exotic plants essential oils on the honeybee pathogen Paenibacillus larvae, causal agent of American foul brood

    Energy Technology Data Exchange (ETDEWEB)

    Fuselli, S. R.; Garcia de la Rosa, S. B.; Eguaras, M. J.; Fritz, R.

    2010-07-01

    Chemical composition and antimicrobial activity of exotic plants essential oils to potentially control Paenibacillus larvae, the causal agent of American foul brood disease (AFB) were determined. AFB represents one of the main plagues that affect the colonies of honeybees Apis mellifera L. with high negative impact on beekeepers worldwide. Essential oils tested were niaouli (Melaleuca viridiflora) and tea tree (Melaleuca alternifolia) from Myrtaceae, and citronella grass (Cymbopogon nardus) and palmarosa (Cymbopogon martinii) from Gramineae. The components of the essential oils were identified by SPME-GC/MS analysis. The antimicrobial activity of the oils against P. larvae was determined by the broth micro dilution method. In vitro assays of M. viridiflora and C. nardus oils showed the inhibition of the bacterial strains at the lowest concentrations tested, with minimal inhibitory concentration (MIC) mean value about 320 mg L{sup -}1 for both oils, respectively. This property could be attributed to the kind and percentage of the components of the oils. Terpinen-4-ol (29.09%), {alpha}-pinene (21.63%) and limonene (17.4%) were predominant in M. viridiflora, while limonene (24.74%), citronelal (24.61%) and geraniol (15.79%) were the bulk of C. nardus. The use of these essential oils contributes to the screening of alternative natural compounds to control AFB in the apiaries; toxicological risks and other undesirable effects would be avoided as resistance factors, developed by the indiscriminate use of antibiotics. (Author) 40 refs.

  6. Variable number of tandem repeat markers in the genome sequence of Mycosphaerella fijiensis, the causal agent of black leaf streak disease of banana (Musa spp).

    Science.gov (United States)

    Garcia, S A L; Van der Lee, T A J; Ferreira, C F; Te Lintel Hekkert, B; Zapater, M-F; Goodwin, S B; Guzmán, M; Kema, G H J; Souza, M T

    2010-11-09

    We searched the genome of Mycosphaerella fijiensis for molecular markers that would allow population genetics analysis of this plant pathogen. M. fijiensis, the causal agent of banana leaf streak disease, also known as black Sigatoka, is the most devastating pathogen attacking bananas (Musa spp). Recently, the entire genome sequence of M. fijiensis became available. We screened this database for VNTR markers. Forty-two primer pairs were selected for validation, based on repeat type and length and the number of repeat units. Five VNTR markers showing multiple alleles were validated with a reference set of isolates from different parts of the world and a population from a banana plantation in Costa Rica. Polymorphism information content values varied from 0.6414 to 0.7544 for the reference set and from 0.0400 and 0.7373 for the population set. Eighty percent of the polymorphism information content values were above 0.60, indicating that the markers are highly informative. These markers allowed robust scoring of agarose gels and proved to be useful for variability and population genetics studies. In conclusion, the strategy we developed to identify and validate VNTR markers is an efficient means to incorporate markers that can be used for fungicide resistance management and to develop breeding strategies to control banana black leaf streak disease. This is the first report of VNTR-minisatellites from the M. fijiensis genome sequence.

  7. Rickettsia typhi IN RODENTS AND R. felis IN FLEAS IN YUCATÁN AS A POSSIBLE CAUSAL AGENT OF UNDEFINED FEBRILE CASES

    Directory of Open Access Journals (Sweden)

    Gaspar PENICHE-LARA

    2015-04-01

    Full Text Available Rickettsia typhi is the causal agent of murine typhus; a worldwide zoonotic and vector-borne infectious disease, commonly associated with the presence of domestic and wild rodents. Human cases of murine typhus in the state of Yucatán are frequent. However, there is no evidence of the presence of Rickettsia typhi in mammals or vectors in Yucatán. The presence of Rickettsia in rodents and their ectoparasites was evaluated in a small municipality of Yucatán using the conventional polymerase chain reaction technique and sequencing. The study only identified the presence of Rickettsia typhi in blood samples obtained from Rattus rattus and it reported, for the first time, the presence of R. felis in the flea Polygenis odiosus collected from Ototylomys phyllotis rodent. Additionally, Rickettsia felis was detected in the ectoparasite Ctenocephalides felis fleas parasitizing the wild rodent Peromyscus yucatanicus. This study’s results contributed to a better knowledge of Rickettsia epidemiology in Yucatán.

  8. In vitro Antagonistic Mechanisms of Trichoderma spp. and Talaromyces flavus to Control Gaeumannomyces graminis var. tritici the Causal Agent of Wheat Take-all Disease

    Directory of Open Access Journals (Sweden)

    Seddighe Mohammadi

    2015-08-01

    Full Text Available Wheat take-all disease caused by Gaeumannomyces graminis var. tritici has recently been detected in different regions of Iran. With respect to biocontrol effect of Trichoderma spp. on many pathogenic fungi, seven isolates of Trichoderma and four isolates of Talaromyces were in vitro evaluated in terms of their biological control against the disease causal agent. In dual culture test the five isolates showed efficient competition for colonization against pathogenic fungus and the highest percentages of inhibition belonging to Talaromyces flavus 60 and Talaromyces flavus 136 were 59.52 and 57.61%, respectively. Microscopic investigations showed that in regions where antagonistic isolates and Gaeumannomyces graminis var. tritici coincide, hyphal contact, penetration and fragmentation of Gaeumannomyces graminis var. tritici were observed. Investigating the effect of volatile and non-volatile compounds at 10 ml concentration showed that the highest inhibition percentage on mycelium growth of the pathogen caused by T. harzianum (44.76% and T. longibrachiatum (52.38% respectively.

  9. Causal Reconstruction

    Science.gov (United States)

    1993-02-01

    suitable source of core events supporting causal reconstruction in a range of domains might be a combination of bodily - kinesthetic and simple...suggested in the previ- ous section, a good place to start might be with causal situations involving bodily - kinesthetic events or simple mechanical events...ANIZATION NAME(S) AND ADDRESS(LS) tý PJIfORMIN’, CRGANIZATION !.LPDRT NUMBEK Artificial Intelligence Laboratory 545 Technology Square AIM 1403 Cambridge

  10. Uneven distribution of mating type alleles in Iranian populations of Cercospora beticola, the causal agent of Cercospora leaf spot disease of sugar beet

    Directory of Open Access Journals (Sweden)

    Mounes BAKHSHI

    2011-05-01

    Full Text Available Normal 0 14 false false false IT ZH-TW X-NONE MicrosoftInternetExplorer4 Cercospora beticola, the causal agent of Cercospora leaf spot disease on sugar beet, is thought to be exclusively asexual because no teleomorph has yet been found. The possibility of a clandestine sexual cycle in the Iranian population of Cercospora beticola was evaluated by analyzing the distribution and frequency of the mating type alleles on a microspatial and a macrogeographical scale. A total of 89 single-conidial Cercospora beticola isolates were obtained from sugar beet fields in the Moghan, the Talesh and the Khoy regions. The isolates were identifed using a Cercospora beticola-specifc primer set in a PCR assay. A multiplex PCR method using previously designed mating type primers was used to study the distribution and the frequency of the mating type alleles. All isolates showed either the 805-bp fragment or the 442-bp fragment of the MAT1-1 and MAT1-2 genes, but no isolate had both fragments. The distribution of the mating type genes in the sampled areas was uneven. From three sugar beet fields sampled in the Moghan region, two fields had only MAT1-1 isolates; while in the third field all isolates had only the MAT1-2 allele. In the Talesh region only MAT1-1 isolates occurred, and in the Khoy region the mating type alleles were uniformly distributed amongst the isolates. The skewed distribution of mating type alleles in Northwestern Iran was in line with the lack of a sexual cycle for this species and may also indicate that sugar fields in the Moghan region were infected by C. beticola populations of different origins. Normal 0 false false false EN-US X-NONE FA

  11. Comparison of cultural growth and in planta quantification of Didymella pinodes, Phoma koolunga and Phoma medicaginis var. pinodella, causal agents of ascochyta blight on field pea (Pisum sativum).

    Science.gov (United States)

    Davidson, J A; Krysinska-Kaczmarek, M; A McKay, Herdina; Scott, E S

    2012-01-01

    The causal agents of ascochyta blight on field pea in South Australia, Didymella pinodes, Phoma medicaginis var. pinodella and Phoma koolunga, are isolated from a single plant within a crop, suggesting competition for space and nutrients. Interactions among these pathogens were investigated. Diameters of colonies of D. pinodes and of P. medicaginis var. pinodella were significantly reduced on PDA amended with filtrate from broth cultures of P. koolunga as were diameters of colonies of D. pinodes on PDA amended with filtrate from P. medicaginis var. pinodella or D. pinodes. This effect was negated when cultures were transferred to unamended PDA, indicating filtrates were fungistatic instead of fungicidal. The diameter of P. koolunga colonies was not influenced by filtrate from any of the three species. When pathogens were co-inoculated in pairs onto leaves on field pea plants, the quantity of DNA of D. pinodes and of P. medicaginis var. pinodella was significantly reduced if co-inoculated with P. koolunga. The quantity of DNA of P. koolunga was not influenced by co-inoculation. When co-inoculated onto excised leaf disks on sterile water the mean lesion diameter due to D. pinodes and to P. medicaginis var. pinodella was significantly reduced if co-inoculated with P. koolunga isolate DAR78535. Lesions caused by D. pinodes were significantly reduced when inoculum was self-paired. Conversely the diameter of lesions caused by P. koolunga DAR78535 increased when self-paired or when co-inoculated with P. medicaginis var. pinodella. Unlike leaf disks on sterile water, co-inoculation had no influence on lesion size or quantity of pathogen DNA in leaf disks on water agar. Antagonism, including self-antagonism, was detected among these species, leading to reduction in lesion size and quantity of pathogen DNA. The slower growing species, P. koolunga, was not self-antagonistic, and in a few instances the effect of co-inoculation was additive or synergistic.

  12. Protective effect of Polygonum orientale L. extracts against Clavibater michiganense subsp. sepedonicum, the causal agent of bacterial ring rot of potato.

    Directory of Open Access Journals (Sweden)

    Jin Cai

    Full Text Available The Polygonum orientale L. extracts were investigated for antibacterial activity against Clavibater michiganense subsp. sepedonicum (Spieckermann & Kotthoff Davis et al., the causal agent of a serious disease called bacterial ring rot of potato. The results showed that the leaf extracts of P. orientale had significantly (p<0.05 greater antibacterial activity against C. michiganense subsp. sepedonicum than root, stem, flower extracts in vitro. According to the results of single factor experiments and L(273(13 orthogonal experiments, optimum extraction conditions were A1B3C1, extraction time 6 h, temperature 80°C, solid to liquid ratio 1∶10 (g:mL. The highest (p<0.05 antibacterial activity was observed when pH was 5, excluding the effect of control. The extracts were stable under ultraviolet (UV. In vivo analysis revealed that 50 mg/mL of P. orientale leaf extracts was effective in controlling decay. Under field conditions, 50 mg/mL of P. orientale leaf extracts also improved growth parameters (whole plant length, shoot length, root length, plant fresh weight, shoot fresh weight, root fresh weight, dry weight, and number of leaves, in the 2010 and 2011 two growing seasons. Further solvent partition assays showed that the most active compounds were in the petroleum ether fractionation. Transmission electron microscopy (TEM showed drastic ultrastructural changes caused by petroleum ether fractionation, including bacterial deformation, electron-dense particles, formation of vacuoles and lack of cytoplasmic materials. These results indicated that P. orientale extracts have strong antibacterial activity against C. michiganense subsp. sepedonicum and a promising effect in control of bacterial ring rot of potato disease.

  13. Growth Simulation and Discrimination of Botrytis cinerea, Rhizopus stolonifer and Colletotrichum acutatum Using Hyperspectral Reflectance Imaging.

    Directory of Open Access Journals (Sweden)

    Ye Sun

    Full Text Available This research aimed to develop a rapid and nondestructive method to model the growth and discrimination of spoilage fungi, like Botrytis cinerea, Rhizopus stolonifer and Colletotrichum acutatum, based on hyperspectral imaging system (HIS. A hyperspectral imaging system was used to measure the spectral response of fungi inoculated on potato dextrose agar plates and stored at 28°C and 85% RH. The fungi were analyzed every 12 h over two days during growth, and optimal simulation models were built based on HIS parameters. The results showed that the coefficients of determination (R2 of simulation models for testing datasets were 0.7223 to 0.9914, and the sum square error (SSE and root mean square error (RMSE were in a range of 2.03-53.40×10(-4 and 0.011-0.756, respectively. The correlation coefficients between the HIS parameters and colony forming units of fungi were high from 0.887 to 0.957. In addition, fungi species was discriminated by partial least squares discrimination analysis (PLSDA, with the classification accuracy of 97.5% for the test dataset at 36 h. The application of this method in real food has been addressed through the analysis of Botrytis cinerea, Rhizopus stolonifer and Colletotrichum acutatum inoculated in peaches, demonstrating that the HIS technique was effective for simulation of fungal infection in real food. This paper supplied a new technique and useful information for further study into modeling the growth of fungi and detecting fruit spoilage caused by fungi based on HIS.

  14. Growth Simulation and Discrimination of Botrytis cinerea, Rhizopus stolonifer and Colletotrichum acutatum Using Hyperspectral Reflectance Imaging.

    Science.gov (United States)

    Sun, Ye; Gu, Xinzhe; Wang, Zhenjie; Huang, Yangmin; Wei, Yingying; Zhang, Miaomiao; Tu, Kang; Pan, Leiqing

    2015-01-01

    This research aimed to develop a rapid and nondestructive method to model the growth and discrimination of spoilage fungi, like Botrytis cinerea, Rhizopus stolonifer and Colletotrichum acutatum, based on hyperspectral imaging system (HIS). A hyperspectral imaging system was used to measure the spectral response of fungi inoculated on potato dextrose agar plates and stored at 28°C and 85% RH. The fungi were analyzed every 12 h over two days during growth, and optimal simulation models were built based on HIS parameters. The results showed that the coefficients of determination (R2) of simulation models for testing datasets were 0.7223 to 0.9914, and the sum square error (SSE) and root mean square error (RMSE) were in a range of 2.03-53.40×10(-4) and 0.011-0.756, respectively. The correlation coefficients between the HIS parameters and colony forming units of fungi were high from 0.887 to 0.957. In addition, fungi species was discriminated by partial least squares discrimination analysis (PLSDA), with the classification accuracy of 97.5% for the test dataset at 36 h. The application of this method in real food has been addressed through the analysis of Botrytis cinerea, Rhizopus stolonifer and Colletotrichum acutatum inoculated in peaches, demonstrating that the HIS technique was effective for simulation of fungal infection in real food. This paper supplied a new technique and useful information for further study into modeling the growth of fungi and detecting fruit spoilage caused by fungi based on HIS.

  15. Epidemiological causality.

    Science.gov (United States)

    Morabia, Alfredo

    2005-01-01

    Epidemiological methods, which combine population thinking and group comparisons, can primarily identify causes of disease in populations. There is therefore a tension between our intuitive notion of a cause, which we want to be deterministic and invariant at the individual level, and the epidemiological notion of causes, which are invariant only at the population level. Epidemiologists have given heretofore a pragmatic solution to this tension. Causal inference in epidemiology consists in checking the logical coherence of a causality statement and determining whether what has been found grossly contradicts what we think we already know: how strong is the association? Is there a dose-response relationship? Does the cause precede the effect? Is the effect biologically plausible? Etc. This approach to causal inference can be traced back to the English philosophers David Hume and John Stuart Mill. On the other hand, the mode of establishing causality, devised by Jakob Henle and Robert Koch, which has been fruitful in bacteriology, requires that in every instance the effect invariably follows the cause (e.g., inoculation of Koch bacillus and tuberculosis). This is incompatible with epidemiological causality which has to deal with probabilistic effects (e.g., smoking and lung cancer), and is therefore invariant only for the population.

  16. Identification and Characterisation of New Microbial Antagonists for Biocontrol of Monilinia laxa, the Causal Agent of Brown Rot on Stone Fruit

    Directory of Open Access Journals (Sweden)

    Peter Jeffries

    2013-10-01

    Full Text Available Monilinia laxa is the causal agent of brown rot disease on stone fruits, and also causes blossom wilt and twig canker. The common practice used to manage this disease is through fungicide treatments. However the demand to reduce fungicide inputs has been increasing and there is a growing number of reports of M. laxa strains that are resistant to fungicides. There is an urgent need to search for an alternative strategy to control the disease. This study focused on the isolation and characterisation of biological control agents (BCAs using indigenous isolates isolated from cherries and plums collected within the UK. A total of 192 isolates were screened against two strains of M. laxa in a series of in vitro dual culture tests. From this in vitro screen, 12 isolates were selected for a subsequent in vivo screen on detached fruits, which then narrowed these isolates down to two potential BCAs. These two strains were identified as Bacillus amyloliquefaciens/subtilis (isolate B91 and Aureobasidium pullulans (isolate Y126. The capability of these two potential BCAs to grow and survive at a range of temperatures likely to be experienced under field and storage conditions was studied in order to gain knowledge for product formulation and field application. Bacillus sp. B91 was shown to be a mesophilic bacterium that could grow at 10–25 °C but suffered significant mortality at 0 and 5 °C, while A. pullulans Y126 was both mesophilic and psychrotolerant as it grew between 0–25 °C with the optimum at 20 °C. When all nutrients were removed, Y126 was able to survive for several weeks in all test temperatures (0–25 °C but showed significant mortality at 25 °C. The capability of B91 to survive at 20 and 25 °C was higher than at low temperatures (0–15 °C. In addition, the modes of action of the potential BCAs were studied. B91 was shown to produce soluble and volatile organic compounds that inhibited M. laxa, while A. pullulans Y126 did not

  17. A revision of the history of the Colletotrichum acutatum species complex in the Nordic countries based on herbarium specimens.

    Science.gov (United States)

    Sundelin, Thomas; Strømeng, Gunn Mari; Gjærum, Halvor B; Amby, Daniel Buchvaldt; Ørstad, Kari; Jensen, Birgit; Lund, Ole Søgaard; Stensvand, Arne

    2015-08-01

    Herbaria collections containing plants with disease symptoms are highly valuable, and they are often the only way to investigate outbreaks and epidemics from the past as the number of viable isolates in culture collections is often limited. Species belonging to the Colletotrichum acutatum complex infect a range of important crops. As members of the C. acutatum complex are easily confused with other Colletotrichum species, molecular methods are central for the correct identification. We performed molecular analyses on 21 herbaria specimens, displaying anthracnose symptoms, collected in Norway and Denmark before the first confirmed findings of C. acutatum complex members in this region. Sequencing parts of the fungal ITS regions showed that members of the species complex were present in 13 of the 21 specimens collected in different parts of Norway and Denmark between 1948 and 1991, representing seven plant hosts (three cherry species, apple, raspberry and rhododendron). This is the first time herbarium specimens have been used to study these pathogens under Nordic conditions. Differences in the ITS sequences suggest the presence of different genotypes within the complex, indicating a well-established population. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  18. In vitro photodynamic inactivation of plant-pathogenic fungi Colletotrichum acutatum and Colletotrichum gloeosporioides with Novel Phenothiazinium photosensitizers.

    Science.gov (United States)

    de Menezes, Henrique D; Rodrigues, Gabriela B; Teixeira, Simone de Pádua; Massola, Nelson S; Bachmann, Luciano; Wainwright, Mark; Braga, Gilberto U L

    2014-03-01

    The increasing tolerance to currently used fungicides in both clinical and agricultural areas is of great concern. The nonconventional light-based approach of antimicrobial photodynamic treatment (APDT) is a promising alternative to conventional fungicides. We evaluated the effects of APDT with four phenothiazinium derivatives (methylene blue [MB], new methylene blue N [NMBN], toluidine blue O [TBO], and the novel pentacyclic phenothiazinium photosensitizer [PS] S137) on conidia of three fungal species (Colletotrichum acutatum, Colletotrichum gloeosporioides, and Aspergillus nidulans). The efficacy of APDT with each PS was determined, initially, based on photosensitizer MICs. Additionally, the effects of APDT with two selected PSs (NMBN and S137) on survival of conidia were evaluated. The subcellular localization of the PS in C. acutatum conidia was determined. The effects of photodynamic treatments on leaves of the plant host Citrus sinensis were also investigated. APDT with S137 showed the lowest MIC. MICs for S137 were 5 μM for the three fungal species when a fluence of 25 J cm(-2) was used. APDT with NMBN (50 μM) and S137 (10 μM) resulted in a reduction in the survival of the conidia of all species of approximately 5 logs with fluences of ≥15 J cm(-2). Washing of the conidia before light exposure did not prevent photodynamic inactivation. Both NMBN and S137 accumulated in cytoplasmic structures, such as lipid bodies, of C. acutatum conidia. No damage to orange tree leaves was observed after APDT.

  19. Extrato etanólico de Senna alata no controle de Myrothecium roridum, agente casual do cancro-de-mirotécio Ethanolic extract of Senna alata in the control of Myrothecium roridum, causal agent of myrothecium leaf spot

    Directory of Open Access Journals (Sweden)

    E.V Medeiros

    2011-09-01

    Full Text Available O fungo M. roridum é o causador da doença cancro-de-mirotécio em meloeiro e vem provocando grandes perdas na produção dessa olerícola. É uma doença de difícil controle, em razão de seu agente ser habitante do solo. Devido à procura de formas alternativas de controle, o objetivo deste trabalho foi avaliar a atividade dos extratos etanólicos de partes de S. alata sobre M. roridum. O delineamento experimental foi inteiramente casualizado, distribuído em esquema fatorial 4 x 6 + 1, sendo o primeiro fator partes da planta (caule, inflorescência, raiz e vagem e o segundo, seis concentrações (0,25; 0,50; 50; 75; 250; e 500 µg mL-1 mais a testemunha, com quatro repetições por tratamento. As variáveis avaliadas foram: taxa de crescimento micelial (TCM, inibição do crescimento micelial (ICM e área abaixo da curva do crescimento micelial (AACCM. Todos os extratos de partes vegetais de S. alata foram eficientes em inibir o crescimento micelial de M. roridum. O extrato etanólico da vagem foi o que melhor inibiu o crescimento de M. roridum, na concentração de 500 µg mL-1 , seguido do extrato da raiz e do caule.The fungus M. roridum is the causal agent of the myrothecium Leaf Spot disease in melon, being responsible for great losses in the production of this olericulture. This disease is difficult to control, since its agent inhabits the soil. Seeking for alternative forms of control, this work aimed to evaluate the effect of the activity of ethanolic extracts of parts of S. alata on M. roridum. The experimental design was completely randomized and distributed in a factorial scheme 4 x 6 + 1, with the first factor being parts of the plant (stalk, flower, root and green bean, and the second factor, six concentrations (0.25; 0.50, 50, 75, 250 and 500 µg mL-1, plus a control, with four repetitions per treatment. The available variables were: mycelial growth rate (MGR, mycelial growth inhibition (MGI and area below mycelial growth curve

  20. Diversidade fenotípica e patogênica de Colletotrichum, agente causal da antracnose em mangueira, e identificação de espécie

    Directory of Open Access Journals (Sweden)

    I.M.R.S. Serra

    2011-03-01

    Full Text Available O presente trabalho teve como objetivo estudar a diversidade fenotípica e patogênica de 40 isolados de Colletotrichum obtidos de mangueira no Nordeste do Brasil e identificar diferentes espécies desse fitopatógeno, agente causal de antracnose, através da análise da seqüência da região ITS do rDNA. Quanto à caracterização morfológica e cultural, as colônias dos isolados apresentaram diversidade em relação à cor e aspecto, sendo mais comum à cor branco-cinza, característica de Colletotrichum gloeosporioides. Não foram observadas variações expressivas na morfologia dos 40 isolados. Os conídios apresentaram-se, predominantemente, hialinos e unicelulares, com formato variando de bastonete para cilíndrico. Todos os isolados produziram apressórios variados em formato e quantidade e apenas 10 isolados apresentaram setas. Para efeito do crescimento micelial e taxa de crescimento foi possível classificar os isolados em sete grupos. Vinte e dois isolados exibiram taxa de crescimento >10mm/dia, considerada típica da espécie C. gloeosporioides. Os isolados foram patogênicos em folhas destacadas de mangueira, induzindo sintomas de antracnose, na forma de manchas escuras levemente deprimidas, e apresentando variações quanto à agressividade. Na identificação específica, baseada na análise da seqüência ITS do DNA ribossomal, 36 isolados amplificaram com o oligonucleotídeos CgInt, específico para C. gloeosporioides e o ITS4, Os isolados CM1, CM4, CM5 e CM10, não amplificaram produtos para nenhum dos oligonucleotídeos específicos, sendo identificados como Colletotrichum spp. Os resultados desse trabalho demonstraram que isolados de Colletotrichum, obtidos de mangueira, apresentam ampla variabilidade morfofisiológica e patogênica. E que, possivelmente, existe mais de uma espécie de Colletotrichum que causa antracnose em mangueira no Nordeste do Brasil.

  1. Antifungal (in vitro activity of plant extracts for the control of anthracnose (Colletotrichum acutatum

    Directory of Open Access Journals (Sweden)

    Villacís-Aldaz Luis Alfredo

    2017-05-01

    Full Text Available The antifungal effect of five plant extracts: nettle (Urtica dioica, chamomile (Chamaemelum nobile, frame (Artemisia vulgaris, lavender (Lavandula officinalis and chamico (Datura ferox were evaluated at laboratory level for control of anthracnose (Colletotrichum acutatum of the tree tomato (Solanum betaceum, using two methods of extraction (maceration and steam trapping, in the results obtained, statistical differences were observed in the percentage of inhibition of mycelial growth of the fungus, the treatment with lavender extract obtained by the steam trapping method presented the greatest efficiency for anthracnose control (66.23%. The other treatments tested also showed effectiveness against the anthracnose pathogen in the following order of inhibition: chamomile (52.78%, frame (21.63, chamico (24.14%, nettle (12.94, the ability of various species to inhibit certain fungal diseases, taking into account the different content of secondary metabolites that have each of the plant species, constituting new clean production alternatives that reduce the use of chemical pesticides for the control of fungal diseases.

  2. Potencial antifúngico de extratos de plantas e de basidiomicetos nativos sobre Colletotrichum acutatum, Alternaria solani e Sclerotium rolfsii

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    Ricardo José Domingues

    2011-09-01

    Full Text Available O emprego de fungicidas na agricultura, principalmente quando utilizados de forma inadequada, tem provocado danos tanto ao homem como ao ambiente. O presente trabalho teve por objetivo o estudo in vitro da eficácia de extratos de três plantas e de dois basidiomicetos nativos do Brasil no controle dos fungos Alternaria solani e Colletotrichum acutatum, causadores de graves prejuízos às culturas de tomate e morango, respectivamente, além de Sclerotium rolfsii, considerado como patógeno polífago. No trabalho foram avaliados: a a inibição de crescimento micelial dos três fitopatógenos, b inibição da germinação de conídios de A. solani e C. acutatum e c inibição da germinação de escleródios de S. rolfsii. Os melhores resultados foram obtidos com o extrato de Oudemansiella canarii, que proporcionou os menores valores de crescimento micelial dos três patógenos, além inibir totalmente a germinação de conídios de A. solani e C. acutatum e de escleródios de S. rolfsii. O extrato de Irpex lacteus inibiu parcialmente o crescimento micelial dos patógenos estudados e o extrato de Avicennia schaueriana promoveu apenas 16 % de inibição do crescimento micelial de S. rolfsii. Nenhum efeito sobre os patógenos foi verificado com os extratos de Senna spectabilis e Senna multijuga nas condições em que foram realizados os experimentos.

  3. Distribuição e identificação de Phakopsora pachyrhizi, agente causal da ferrugem da soja no estado de Minas Gerais Identification and distribution of Phakopsora pachyrhizi causal agente of the Asian rust in the Minas Gerais State

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    Patrícia Ferreira Cunha Sousa

    2007-06-01

    guide the planning control measures. The molecular characterization based on PCR has been showing as useful tool to satisfy that need. In this study 86 samples of leaves infected by Phakopsora from the main areas producing soybean in the State of Minas Gerais (Triângulo, Alto Paranaíba, Noroeste, Sudoeste and Sul were used. The extraction of DNA was made by the method of CTAB. For the polimerase chain reaction, specific primers were used for each species, been primer Ppm1/Ppa2 specific for P. pachyrhizi and Ppm1/Pme2 specific for P. meibomiae. The results showed that the 86 samples belonged to the species P. pachyrhizi, agent causal of the "Asian" rust. In other words, there was the production of bands specific from the group primer Ppm1/Ppa2 with approximate size of 141 pairs of bases. These results show that the species Phakopsora present in 100% of the areas analyzed in the State of Minas Gerais was P. pachyrhizi. This information is important to guide futures breeding programs for resistance to the agent of soybean rust in the State.

  4. Acción inhibitoria de una cepa de Zymomonas mobilis mobilis aislada de caña de azúcar sobre Xanthomonas citri subsp. citri, agente causal de la cancrosis de los cítricos Inhibition of Xanthomonas citri subsp. citri, causal agent of citrus canker, by a strain of Zymomonas mobilis mobilis isolated from sugarcane

    Directory of Open Access Journals (Sweden)

    María E. Romero

    2008-06-01

    a wide range of microorganisms pathogenic to man, animals, and plants. An important problem to solve with antimicrobial treatments is the development of resistance in these microorganisms, including phytopathogenic bacteria, to the currently used active ingredients. In this study, antagonism tests with cells (cross-streaking and cell-free culture supernatants (CCS (agar diffusion test from Zm cultures, isolated from sugarcane juice in Tucumán, were carried out, measuring activity against Xanthomonas citri subsp. citri (Xcc, the causal agent of citrus canker. Xcc isolates sensitive (Xc and resistant (Xcr to copper pesticides were included in these tests. Results showed that indicator bacteria were completely inhibited by cells of Zm, which had a bactericide effect. Both Xc and Xcr were sensitive to the CCS in the agar diffusion method. Previous studies had revealed the deleterious effects of metabolites from Zm on cell membranes of E. coli AB1133, inhibiting the respiration of the bacteria inmediately after CCS addition. On the basis of these results, the effects of CCS on Xcc respiration were studied, verifyng a similar response. This would indicate that the site of action of these antimicrobial compounds is also located at the cell membrane of the bacteria under study. Based on these results, additional studies are suggested to evaluate Zm-derived products on the control of diseases that affect economically important crops, such as citrus canker.

  5. Voortgezet diagnostisch onderzoek naar een betere beheersing van een aantasting door de schimmel Colletotrichum acutatum bij de bollenteelt van tulpen cv. Giuseppe Verdi

    NARCIS (Netherlands)

    Vink, P.

    2008-01-01

    Sinds 1992 kennen we een ziekte bij de teelt van tulpen in metname de cultivar Giuseppe Verdi (en de laatste tijd ook wel eens in andere tulpencultivars) waarbij de bollen worden aangetast door de schimmel Colletotrichum acutatum. Daardoor gaan de bollen na de oogst verloren of groeien er in een

  6. Inactivation of plant-pathogenic fungus Colletotrichum acutatum with natural plant-produced photosensitizers under solar radiation.

    Science.gov (United States)

    Fracarolli, Letícia; Rodrigues, Gabriela B; Pereira, Ana C; Massola Júnior, Nelson S; Silva-Junior, Geraldo José; Bachmann, Luciano; Wainwright, Mark; Bastos, Jairo Kenupp; Braga, Gilberto U L

    2016-09-01

    The increasing tolerance to currently used fungicides and the need for environmentally friendly antimicrobial approaches have stimulated the development of novel strategies to control plant-pathogenic fungi such as antimicrobial phototreatment (APT). We investigated the in vitro APT of the plant-pathogenic fungus Colletotrichum acutatum with furocoumarins and coumarins and solar radiation. The compounds used were: furocoumarins 8-methoxypsoralen (8-MOP) and 5,8-dimethoxypsoralen (isopimpinellin), coumarins 2H-chromen-2-one (coumarin), 7-hydroxycoumarin, 5,7-dimethoxycoumarin (citropten) and a mixture (3:1) of 7-methoxycoumarin and 5,7-dimethoxycoumarin. APT of conidia with crude extracts from 'Tahiti' acid lime, red and white grapefruit were also performed. Pure compounds were tested at 50μM concentration and mixtures and extracts at 12.5mgL(-1). The C. acutatum conidia suspension with or without the compounds was exposed to solar radiation for 1h. In addition, the effects of APT on the leaves of the plant host Citrus sinensis were determined. APT with 8-MOP was the most effective treatment, killing 100% of the conidia followed by the mixture of two coumarins and isopimpinellin that killed 99% and 64% of the conidia, respectively. APT with the extracts killed from 20% to 70% of the conidia, and the extract from 'Tahiti' lime was the most effective. No damage to sweet orange leaves was observed after APT with any of the compounds or extracts. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. PRESENCIA DE Colletotrichum acutatum y Colletotrichum gloeosporioides EN HELECHO HOJA DE CUERO, LIMÓN CRIOLLO, PAPAYA, CARAMBOLA Y MANGO EN COSTA RICA Y FLORIDA (ESTADOS UNIDOS

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    Marcia Barquero Quir\\u00F3s

    2013-01-01

    Full Text Available La antracnosis es una enfermedad causada por varias especies del género Colletotrichum en diferentes hospederos. C. acutatum y C. gloeosporioides son especies morfológicamente similares, que pueden causar síntomas similares en el mismo hospedero. Se colectaron 220 aislamientos de Colletotrichum de muestras con síntomas típicos de antracnosis en helecho hoja de cuero (Rumohra adiantiformis, limón criollo (Citrus aurantifolia, carambola (Averrhoa carambola, papaya (Carica papaya y mango (Mangifera indica en Costa Rica y Florida, Estados Unidos. Los aislamientos se caracterizaron por morfología de colonia, sensibilidad al benomil, y PCR con los iniciadores específicos para C. acutatum y C. gloeosporioides CaInt2 y Cg/fInt1, respectivamente; también se analizó la morfología de las colonias de ambas especies. De los 85 aislamientos obtenidos de mango, todos los aislamientos de Florida fueron identificados como C. acutatum, mientras que todos los aislamientos de Costa Rica fueron C. gloeosporioides. De los 60 aislamientos de carambola, 3 provenientes de Costa Rica fueron C. acutatum (primer informe y el resto fueron C. gloeosporioides. Todos los aislamientos de helecho hoja de cuero (25 aislamientos y de limón criollo (25 aislamientos se identificaron como C. acutatum. Los demás aislamientos de carambola y mango así como todos los aislamientos de papaya, se identificaron como C. gloeosporioides. No se encontró diferenciación de síntomas entre ambas especies sobre los hospederos donde se encontraron.

  8. EFECTO DEL VERMICOMPOSTAJE SOBRE LAS POBLACIONES DE Colletotrichum acutatum y Pectobacterium carotovorum PRESENTES EN RESIDUOS DE PLANTAS

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    Lidieth Uribe

    2009-01-01

    Full Text Available Se evaluó el efecto del vermicompostaje en la eliminación del hongo Colletotrichum acutatum presente en residuos del helecho hoja de cuero (Rumohra adiantiformis y de la bacteria Pectobacterium carotovorum inoculada en residuos de papa (Solanum tuberosum. En ambos ensayos se utilizaron cajas de madera divididas en 3 compartimentos, en la sección central se colocó sustrato con lombrices (Eisenia foetida y en las secciones laterales el material infectado respectivo. Los compartimentos se dividieron con mallas que permitieron el paso de las lombrices al tratamiento de vermicompostaje pero no al testigo. Se determinó la presencia de C. acutatum en los residuos de helecho mediante recuentos semanales de conidias durante 70 días. La población de P. carotovorum en los residuos de papa se evaluó utilizando la técnica de recuento en plato en medios específicos a los 26 y a los 41 días, y por la técnica de número más probable (NMP al día 54. Si bien el número de esporas de C. acutatum disminuyó en ambos tratamientos, a partir del día 35, se observó una mayor reducción en el tratamiento con lombrices que en el tratamiento testigo. Hacia el final del experimento, el número de conidias se redujo 100 veces con respecto a la población original en el tratamiento vermicompostaje y 10 veces en el tratamiento testigo. En el caso de los desechos de papa, al día 41 la disminución en la población de P. carotovorum fue 100 veces mayor en el tratamiento de vermicompostaje que en el control, no detectándose la bacteria al día 54 en el tratamiento con lombrices. La reducción de las poblaciones de patógenos en el tratamiento de vermicompostaje se atribuye al efecto directo (degradación, e indirecto (cambios en pH, efecto cualitativo sobre poblaciones de microorganismos que la lombriz roja ejerce sobre los residuos infectados.

  9. Phenotypic and molecular characterization of the causal agent of chafer beetle mortality in the wheat fields of the Kurdistan province, Iran

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    Karimi Keivan

    2015-07-01

    Full Text Available We report the first case of chafer beetle [Anisoplia austriaca (Herbst 1783] mortality caused by Actinomucor elegans var. elegans in wheat fields of the Kurdistan province, Iran. For three years, dead larvae of Anisoplia austriaca were collected from wheat fields of the Kurdistan province. Similar isolates of a fast-growing fungus were recovered from all samples. The fungal isolates were identified as A. elegans var. elegans based on morphological and cultural characteristics. The identity of the species was further confirmed using sequence data of the ITS (Internal Transcribed Spacer region of ribosomal DNA. Koch’s postulates were fulfilled by the inoculation of the larvae of A. austriaca and Galleria mellonella (Linnaeus, 1758 (as the model insect using the spore suspension of A. elegans var. elegans. The viability of sporangiospores was evaluated using a spore dilution technique on germination medium. The results on the pathogenicity (100% mortality in A. austriaca larvae and viability tests (germination: 95.45% demonstrated that A. elegans var. elegans can be considered as a potential biocontrol agent against the chafer beetle. Field experiments are still required to evaluate the capacity of A. elegans as a biological control agent.

  10. Causal reasoning in physics

    CERN Document Server

    Frisch, Mathias

    2014-01-01

    Much has been written on the role of causal notions and causal reasoning in the so-called 'special sciences' and in common sense. But does causal reasoning also play a role in physics? Mathias Frisch argues that, contrary to what influential philosophical arguments purport to show, the answer is yes. Time-asymmetric causal structures are as integral a part of the representational toolkit of physics as a theory's dynamical equations. Frisch develops his argument partly through a critique of anti-causal arguments and partly through a detailed examination of actual examples of causal notions in physics, including causal principles invoked in linear response theory and in representations of radiation phenomena. Offering a new perspective on the nature of scientific theories and causal reasoning, this book will be of interest to professional philosophers, graduate students, and anyone interested in the role of causal thinking in science.

  11. Theories of Causality

    Science.gov (United States)

    Jones, Robert

    2010-03-01

    There are a wide range of views on causality. To some (e.g. Karl Popper) causality is superfluous. Bertrand Russell said ``In advanced science the word cause never occurs. Causality is a relic of a bygone age.'' At the other extreme Rafael Sorkin and L. Bombelli suggest that space and time do not exist but are only an approximation to a reality that is simply a discrete ordered set, a ``causal set.'' For them causality IS reality. Others, like Judea Pearl and Nancy Cartwright are seaking to build a complex fundamental theory of causality (Causality, Cambridge Univ. Press, 2000) Or perhaps a theory of causality is simply the theory of functions. This is more or less my take on causality.

  12. Causality in Science

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    Cristina Puente Águeda

    2011-10-01

    Full Text Available Causality is a fundamental notion in every field of science. Since the times of Aristotle, causal relationships have been a matter of study as a way to generate knowledge and provide for explanations. In this paper I review the notion of causality through different scientific areas such as physics, biology, engineering, etc. In the scientific area, causality is usually seen as a precise relation: the same cause provokes always the same effect. But in the everyday world, the links between cause and effect are frequently imprecise or imperfect in nature. Fuzzy logic offers an adequate framework for dealing with imperfect causality, so a few notions of fuzzy causality are introduced.

  13. Evaluación a nivel de laboratorio del efecto de 7 extractos vegetales para el control de Colletotrichum sp agente causal de la antracnosis en el cultivo de tomate de árbol - Evaluación a nivel de laboratorio del efecto de 7 extractos vegetales para el control de Colletotrichum sp agente causal de la antracnosis en el cultivo de tomate de árbol

    Directory of Open Access Journals (Sweden)

    Christian Andrei Chacin Zambrano

    2013-08-01

    Full Text Available Was evaluated in the laboratory the effect of seven plant extracts of Neem leaves and fruit (Azadirachta indica leaves of lemon grass (Swinglea glutinosa, leaves of papaya (Carica papaya, Pringamosa leaves (Urtica dioica, eucalyptus leaves (Eucalyptus camaldulensis Dehn fruits of garlic (Allium sativum L. and fruits of pepper (Capsicum annuum in the control of the fungus Colletotrichum sp causal agent of anthracnose in tomato crop tree (Cyphomandra betacea. The pathogen was isolated on PDA medium from tomato fruit tree, the extracts were obtained taking into account the process by (Marin, et. Al 2007, which consists of chopping and blending plant material deposited in plastic bucket, add water ratio 2.5:1 (water: sample processed, vol.: w, subjecting to fermentation for 24 hours. The produto was filtered using sterile gauze and package them for further evaluation. The concentrations of the treatments that worked were 25, 50, 75 and 100% of the infectious agent, determining the degree of inhibition of the pathogen in Petri dishes. The best results were obtained with the application of eucalyptus leaves, since its effect was 100% at all concentrations, without neglecting the fruits of the Neem and garlic with inhibition percentages of 75 and 60% respectively, had a behavior directly proportional to the concentrations used, since the greater the amount of extract the inhibitory effect was better in this case 75% and 100%.

  14. Functional and biophysical studies on four ceratoplatanins from the fungus Moniliophthora perniciosa, causal agent of the Witche's broom disease

    Energy Technology Data Exchange (ETDEWEB)

    Barsottini, M.; Zaparoli, G.; Garcia, O.; Pereira, G.A.G. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil); Oliveira, J.F.; Tiezzi, H.O.; Ambrosio, A.L.B.; Dias, S.M.G. [Laboratorio Nacional de Biociencias - LNBIO, Campinas, SP (Brazil)

    2012-07-01

    Full text: Ceratoplatanin (CP) is a secreted protein of 12.4 kDa initially identified in culture filtrates of the disease ascomycete Ceratocystis fimbriata f. sp. platani, etiological agent of the canker stain disease. CP is also the founding member of the namesake protein family, which contains fungal-secreted proteins involved in various stages of the host-fungus interaction and may act as phytotoxins or elicitors of defense response. Besides the low molecular weight, CPs have a high percentage of hydrophobic residues and share two conserved intramolecular disulfide bonds. It has been suggested that CPs have important physiological functions, including interaction with cell wall or cell membrane and manipulation of the host's defense system. Furthermore, a recent work showed that the ceratoplatanin from C. fimbriata has some degree of affinity for the saccharide 4-N-acetylglucosamine. However, its precise molecular function remains elusive. Five putative CPs have been identified in Moniliophthora perniciosa a basidiomycete fungus responsible for great economic losses in cocoa industry in the form of Witches' broom disease (WBD) , four of which had their crystal structures resolved by our group. In this work we report biophysical and functional studies on these MpCPs aiming at understanding their role and importance during the WBD progression. (author)

  15. Biocontrol traits and antagonistic potential of Bacillus amyloliquefaciens strain NJZJSB3 against Sclerotinia sclerotiorum, a causal agent of canola stem rot.

    Science.gov (United States)

    Wu, Yuncheng; Yuan, Jun; Raza, Waseem; Shen, Qirong; Huang, Qiwei

    2014-10-01

    Bacillus amyloliquefaciens strain NJZJSB3 has shown antagonism of several phytopathogens in vitro, especially Sclerotinia sclerotiorum. Both the broth culture and cell suspension of strain NJZJSB3 could completely protect the detached leaves of canola (Brassica napus) from S. sclerotiorum infection. In pot experiments, the application of strain NJZJSB3 cell suspension (10(8) CFU/ml) decreased the disease incidence by 83.3%, a result similar to commercially available fungicide (Dimetachlone). In order to investigate the potential biocontrol mechanisms of strain NJZJSB3, the nonvolatile antifungal compounds it produces were identified as iturin homologs using HPLC-ESI-MS. Antifungal volatile organic compounds were identified by gas chromatography-mass spectrometry. The detected volatiles toluene, phenol, and benzothiazole showed antifungal effects against S. sclerotiorum in chemical control experiments. Strain NJZJSB3 also produced biofilm, siderophores and cell-wall-degrading enzymes (protease and β-1,3-glucanase). These results suggest that strain NJZJSB3 can be a tremendous potential agent for the biological control of sclerotinia stem rot.

  16. The effect of locust bean gum (LBG)-based edible coatings carrying biocontrol yeasts against Penicillium digitatum and Penicillium italicum causal agents of postharvest decay of mandarin fruit.

    Science.gov (United States)

    Parafati, Lucia; Vitale, Alessandro; Restuccia, Cristina; Cirvilleri, Gabriella

    2016-09-01

    Strains belonging to Wickerhamomyces anomalus, Metschnikowia pulcherrima and Aureobasidium pullulans species were tested in vitro as biocontrol agents (BCAs) against the post-harvest pathogenic molds Penicillium digitatum and Penicillium italicum. Moreover, studies aimed at screening the antifungal activity of selected yeast strains in vivo conditions against P. digitatum and P. italicum, and investigated the efficacy of a polysaccharidic matrix, locust bean gum (LBG), enriched with the tested BCAs, in controlling postharvest decays in artificially inoculated mandarins. The population dynamics of BCAs on wounds and the magnitude of peroxidase (POD) and superoxide dismutase (SOD) in fruit tissues were also investigated after treatments of mandarins with antagonistic yeasts. W. anomalus BS91, M. pulcherrima MPR3 and A. pullulans PI1 provided excellent control of postharvest decays caused by P. digitatum and P. italicum on mandarins, both when the yeasts were used alone and in combination with LBG, which enhanced the yeast cell viability over time. Finally, the increased activity of POD and lower decrease in SOD activity in response to BCAs application in mandarin fruits confirmed their involvement in the biocontrol mechanism. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Efeito inibitório de extratos vegetais sobre Colletotrichum gloeosporioides - agente causal da podridão de frutos de mamoeiro

    Directory of Open Access Journals (Sweden)

    Ribeiro Luiz Fernando

    1999-01-01

    Full Text Available Extratos aquosos foram obtidos a partir de bulbilhos de alho, folhas de hortelã e mamona e frutos de pimenta. Após a incorporação destes extratos em BDA, obtendo-se concentrações de 100, 200, 500, 1000, 5000 e 10000 ppm, foi avaliado o crescimento e a produção de conídios de um isolado de Colletotrichum gloeosporioides, agente de podridão em frutos de mamoeiro. Os resultados demonstraram o efeito inibitório dos diferentes extratos a partir da concentração de 200 ppm. O extrato de alho inibiu o crescimento micelial, em porcentagens variáveis de 5,3 a 67,6%, porém não atuou de modo expressivo sobre a produção de conídios. Em contraposição, os extratos de hortelã, mamona e pimenta promoveram inibição menos acentuada do crescimento de micélio, porém reduziram drasticamente a produção de conídios em níveis variáveis de 41 a 84%, de acordo com as concentrações crescentes dos mesmos. As propriedades fungitóxicas detectadas nos extratos utilizados no ensaio evidenciaram o uso potencial dos mesmos como alternativa aos métodos físicos e químicos convencionalmente usados para o controle da doença.

  18. INHIBITORY POWER OF EXTRACT OF SOURSOP LEAF (Annona Muricata, KIRINYUH (Chromolaena Odorata AND GALANGAL RHIZOMES (Alpinia Galanga ON Colletotricuhum Acutatum COLONY GROWTH IN VITRO

    Directory of Open Access Journals (Sweden)

    Ida Hodiyah

    2017-12-01

    Full Text Available Several plants that are potentially used as bio-pesticides are soursop, siam weed, and galangal. The research objective was to find out the effectiveness of leaf extract of soursop and C. odorata, and extract of galangal rhizome in inhibiting the growth of Colletotrichum acutatum colonies, causing antracnose on chilli, in in vitro. The experiment was conducted in the laboratory of Agriculture Faculty, Universitas Siliwangi Tasikmalaya from July until August 2016. The research design used was a completely randomized design consisted of nine treatments and three replications. The treatments were A ( control; B (soursop leaf extract, 0,5%; C (soursop leaf extract, 1%; D (C. odorata leaf extract, 0,5 %; E (C. odorata leaf extract 1%; F (galangal rhizome extract 0,5%; G (galangal rhizome extract 1%; H (mixture of soursop leaf extract, C. odorata leaf extract, and galangal rhizome extract each 0,5%; and I (mixture of soursop leaf extract, C. odorata leaf extract, and galangal rhizome extract each 1%. The results showed that the mixture of each 1% soursop leaf extract, C.odorata leaf extract and galangal rhizome extract was effective in inhibiting the growth of C. acutatum colonies at 7 and 14 days incubation period by 66,19% and 69,94% respectively. The three extracts are potentials as anti-fungus of C. acutatum.

  19. Visual Causal Feature Learning

    OpenAIRE

    Chalupka, Krzysztof; Perona, Pietro; Eberhardt, Frederick

    2014-01-01

    We provide a rigorous definition of the visual cause of a behavior that is broadly applicable to the visually driven behavior in humans, animals, neurons, robots and other perceiving systems. Our framework generalizes standard accounts of causal learning to settings in which the causal variables need to be constructed from micro-variables. We prove the Causal Coarsening Theorem, which allows us to gain causal knowledge from observational data with minimal experimental effort. The theorem prov...

  20. Reasoning with Causal Cycles

    Science.gov (United States)

    Rehder, Bob

    2017-01-01

    This article assesses how people reason with categories whose features are related in causal cycles. Whereas models based on causal graphical models (CGMs) have enjoyed success modeling category-based judgments as well as a number of other cognitive phenomena, CGMs are only able to represent causal structures that are acyclic. A number of new…

  1. Causality in demand

    DEFF Research Database (Denmark)

    Nielsen, Max; Jensen, Frank; Setälä, Jari

    2011-01-01

    This article focuses on causality in demand. A methodology where causality is imposed and tested within an empirical co-integrated demand model, not prespecified, is suggested. The methodology allows different causality of different products within the same demand system. The methodology is applied...

  2. Identification of a second family of genes in Moniliophthora perniciosa, the causal agent of witches' broom disease in cacao, encoding necrosis-inducing proteins similar to cerato-platanins.

    Science.gov (United States)

    Zaparoli, Gustavo; Cabrera, Odalys García; Medrano, Francisco Javier; Tiburcio, Ricardo; Lacerda, Gustavo; Pereira, Gonçalo Guimarães

    2009-01-01

    The hemibiotrophic basidiomycete Moniliophthora perniciosa is the causal agent of witches' broom disease in cacao. This is a dimorphic species, with monokaryotic hyphae during the biotrophic phase, which is converted to dikaryotic mycelia during the saprophytic phase. The infection in pod is characterized by the formation of hypertrophic and hyperplasic tissues in the biotrophic phase, which is followed by necrosis and complete degradation of the organ. We found at least five sequences in the fungal genome encoding putative proteins similar to cerato-platanin (CP)-like proteins, a novel class of proteins initially found in the phytopathogen Ceratocystis fimbriata. One M. perniciosa CP gene (MpCP1) was expressed in vitro and proved to have necrosis-inducing ability in tobacco and cacao leaves. The protein is present in solution as dimers and is able to recover necrosis activity after heat treatment. Transcription analysis ex planta showed that MpCP1 is more expressed in biotrophic-like mycelia than saprotrophic mycelia. The necrosis profile presented is different from that caused by M. perniciosa necrosis and ethylene-inducing proteins (MpNEPs), another family of elicitors expressed by M. perniciosa. Remarkably, a mixture of MpCP1 with MpNEP2 led to a synergistic necrosis effect very similar to that found in naturally infected plants. This is the first report of a basidiomycete presenting both NEP1-like proteins (NLPs) and CPs in its genome.

  3. Endophytic bacteria from Piper tuberculatum Jacq.: isolation, molecular characterization, and in vitro screening for the control of Fusarium solani f. sp piperis, the causal agent of root rot disease in black pepper (Piper nigrum L.).

    Science.gov (United States)

    Nascimento, S B; Lima, A M; Borges, B N; de Souza, C R B

    2015-07-06

    Endophytic bacteria have been found to colonize internal tissues in many different plants, where they can have several beneficial effects, including defense against pathogens. In this study, we aimed to identify endophytic bacteria associated with roots of the tropical piperaceae Piper tuberculatum, which is known for its resistance to infection by Fusarium solani f. sp piperis, the causal agent of black pepper (Piper nigrum) root rot disease in the Amazon region. Based on 16S rRNA gene sequence analysis, we isolated endophytes belonging to 13 genera: Bacillus, Paenibacillus, Pseudomonas, Enterobacter, Rhizobium, Sinorhizobium, Agrobacterium, Ralstonia, Serratia, Cupriavidus, Mitsuaria, Pantoea, and Staphylococcus. The results showed that 56.52% of isolates were associated with the phylum Proteobacteria, which comprised α, β, and γ classes. Other bacteria were related to the phylum Firmicutes, including Bacillus, which was the most abundant genus among all isolates. Antagonistic assays revealed that Pt12 and Pt13 isolates, identified as Pseudomonas putida and Pseudomonas sp, respectively, were able to inhibit F. solani f. sp piperis growth in vitro. We describe, for the first time, the molecular identification of 23 endophytic bacteria from P. tuberculatum, among which two Pseudomonas species have the potential to control the pathogen responsible for root rot disease in black pepper in the Amazon region.

  4. Osmotic dehydration of apple slices with CaCl2 and sucrose limits decay caused by Penicillium expansum, Colletotrichum acutatum, and Botrytis cinerea and does not promote Listeria monocytogenes or total aerobic population growth.

    Science.gov (United States)

    Chardonnet, Catherine O; Sams, Carl E; Conway, William S; Draughon, Frances A; Mount, John R

    2002-01-01

    The interaction of Penicillium expansum Link, Colletotrichum acutatum, and Botrytis cinerea Pers.:Fr. with Listeria monocytogenes on osmotically dehydrated apple slices was evaluated. In mineral analyses of the slices, the calcium content of the peel and flesh tissues increased by 4- and 11-fold, respectively, when processed in 2% CaCl2. These slices also exhibited less decay by P. expansum, C. acutatum, and B. cinerea. Inoculation of slices with P. expansum resulted in a decrease in the pH of the flesh tissue at the infection site, while the pHs of slices infected with C. acutatum and B. cinerea increased and remained stable, respectively. Total mold population increased in wounds inoculated with P. expansum or C. acutatum. The presence of L. monocytogenes in the wounds did not significantly affect mold growth. The association of P. expansum and L. monocytogenes on apple slices resulted in a decrease in the bacterial population, whereas L. monocytogenes survived when slices were inoculated with C. acutatum. When associated with B. cinerea, there was a fourfold decrease in the L. monocytogenes population when slices were treated with 2% CaCl2. The total aerobic population was not significantly affected by the type of microorganism added to the wounds or by the osmotic treatment. These data show that osmotic dehydration with 2% CaCl2 combined with 20% sucrose limits decay of apple slices and does not promote bacterial or total aerobic population growth.

  5. Onicomicosis: epidemiología, agentes causales y evaluación de los métodos diagnósticos de laboratorio Onychomycoses: epidemiology, causative agents and assessment of diagnostic laboratory methods

    Directory of Open Access Journals (Sweden)

    Javier R Nazar

    2012-03-01

    Full Text Available Desde marzo de 2007 hasta marzo de 2011 se estudiaron prospectivamente 414 pacientes con onicodistrofias en un laboratorio privado de Esquel. La prevalencia de onicomicosis de pie fue del 78 %; la de mano, del 58 %. Los principales agentes etiológicos fueron Trichophyton rubrum, Candida spp. y Trichophyton mentagrophytes. El desarrollo de dermatofitos prevaleció en las onicopatías de pie y el de Candida spp. en las de uñas de mano (ambos, p Since March 2007 to March 2011, 414 patients with onychopathies were prospectively analyzed. Prevalence of the toenail and fingernail mycoses was 78 % and 58 %, respectively. The major etiological agents were Trichophyton rubrum, Candida spp. and Trichophyton mentagrophytes. Dermatophytes were more frequently cultured from toenails, whereas Candida spp. from fingernails (both, p < 0.05. In candidal onychomycosis, species different from C. albicans were prevalent. A higher prevalence of toenail and fingernail mycoses, a predominance of T. rubrum in toenails (p < 0.05, and greater positivity in the direct examination (DE and in culture (both, p < 0.05 were more frequently observed in men than in women. The correlation between DE and culture was 68 %. DE and culture yields were associated with a greater size lesion. DE was more effective in onycodystrophies with duration of more than 5 years. Culture positivity was independent of nail affection chronicity.

  6. INDUCCIÓN DE FENILALANINA AMONIO LIASA EN FRUTOS DE LULO (Solanum quitoense Lam INFECTADOS CON Colletotrichum acutatum.

    Directory of Open Access Journals (Sweden)

    Martínez Peralta Sixta Tulia

    2010-04-01

    Full Text Available

    Se evaluó la dinámica de la actividad fenilalanina amonio liasa (PAL en corteza de frutos de lulo (Solanum quitoense Lam con el fin de determinar su participación en respuestas bioquímicas hacia Colletotrichum acutatum. Se establecieron como mejores condiciones para la extracción de la enzima, amortiguador ácido bórico-borato de sodio 0.1M pH 8.8, 1% SDS, 3% PVPP y para medir la actividad, sustrato L-fenilalanina 5 mM, pH 8,0, 20°C, 30 μL de extracto y 45 min. Se realizó un ensayo in vivo usando frutos en tres estados de madurez, los cuales fueron inoculados con el patógeno o tratados con agua estéril. A cinco tiempos (hpi se determinó la actividad PAL y el contenido total de fenoles, encontrándose que hay una respuesta diferencial de la enzima por efecto del patógeno y por el estado de madurez. Para frutos en el estado pintón se obtuvo el mayor aumento de PAL, el que perduró hasta 48 hpi, al compararlo con los controles y con los otros dos estados de madurez. Este aumento mostró relación con un marcado incremento en el contenido total de fenoles y con el desarrollo más tardío de síntomas característicos de antracnosis, observado para los frutos pintones. Estos resultados permiten postular, una posible relación positiva entre inducción de PAL, aumento de fenólicos y respuesta de tolerancia a C. acutatum. Para lulos en estado verde y maduro se observó aumento de PAL a 12 y 24 hpi que coincidió también con incremento en el contenido de fenoles totales, aunque para estos dos últimos estados dicho contenido disminuyó significativamente a tiempos mayores.

  7. Novas raças de Bremia lactucae, agente causador do míldio da alface, identificadas no estado de São Paulo New races of Bremia lactucae, causal agent of lettuce downy mildew, identified in São Paulo state, Brazil

    Directory of Open Access Journals (Sweden)

    Jean de O Souza

    2011-09-01

    Full Text Available O objetivo deste trabalho foi relatar o surgimento de raças de Bremia lactucae, agente causal do míldio nas principais regiões produtoras de alface do estado de São Paulo. O estudo foi realizado no Laboratório de Melhoramento Genético de Hortaliças do Departamento de Produção Vegetal da UNESP, Campus de Jaboticabal. No período de 2006 e 2007, foram coletados 36 isolados de B. lactucae de diferentes regiões produtoras de alface no estado. Para identificação das raças foram utilizadas as cultivares diferenciadoras conforme o código "Sextet". Foram identificadas três novas raças, SPBl:02, SPBl:03 e SPBl:04 com os referidos comportamentos do fungo: (63/31/19/00, (63/63/19/00 e (63/63/03/00. Os genes Dm-14, Dm-17, Dm-18, Dm-37 e Dm-38 conferem resistência a essas novas raças identificadas.The objective of this paper was to report new races of lettuce downy mildew causal agent Bremia lactucae in São Paulo State. The study was carried out in the laboratory of Crop Genetics in the Department of Crop Science at the college of Agricultural and Veterinary Sciences, Jaboticabal campus. A total of 36 isolates of B. lactucae was collected in different regions. The identification of races was based on compatibility reaction on the differential cultivars of the "Sextet". Three new races of B. lactucae, SPBl:02 (63/31/19/00, SPBl:03 (63/63/19/00 and SPBl:04 (63/63/03/00 were identified according to "Sextet" code. Genes Dm-14, Dm-17, Dm-18, Dm-37 and Dm-38 confer resistance to these new races identified.

  8. BIOTRANSFORMACIÓN DE LOS SUSTRATOS 2-FENILETANOL Y ACETOFENONA CON EL HONGO FITOPATÓGENO Colletotrichum acutatum

    Directory of Open Access Journals (Sweden)

    Diego Aristizábal

    2009-03-01

    Full Text Available En este estudio se evaluaron las biotransformaciones realizadas por el hongo fitopatógeno Colletotrichum acutatum, sobre los sustratos 2-feniletanol 1 y acetofenona 2; los procesos se realizaron en el medio de cultivo líquido Czapeck-Dox a temperatura promedio de 24 oC, humedad relativa entre 45 % y 60 % y agitación a 150 rpm en un agitador orbital tipo shaker.  En la biotransformación a partir del sustrato 1 se obtuvieron los productos metabólicos 1-fenil-1,2-etanodiol 3, (2-metoxietilbenceno 4 y acetato de 2-feniletilo 5, y desde el sustrato 2 los compuestos 1-fenil-1,2-etanodiol 3, 1-feniletanol 6 y 2-feniletanol 1.  Los productos de la transformación microbiana se identificaron mediante cromatografía de gases acoplada a espectrometría de masas (CG-EM y resonancia magnética nuclear de protón y carbono (RMN 1H y 13C. Se observó una tendencia marcada del patógeno a producir hidroxilaciones sobre el sustituyente del anillo aromático; igualmente tiene la capacidad de reducir el grupo carbonilo y esterificar los grupos hidroxilo de alcoholes primarios.  Se discute una posible ruta metabólica para la transformación de los sustratos.

  9. Caracterización taxonómica y análisis de la variabilidad del agente causal del cancro del tallo de la soja en Buenos Aires (2005/2007

    Directory of Open Access Journals (Sweden)

    GRIJALBA, P.E

    2011-12-01

    Full Text Available ResumenEl complejo Diaporthe/Phomopsis es un importante grupo de hongos patógenos de la soja. Dentro del mismo, Diaporthe phaseolorum var. caulivora es uno de los agentes causales del cancro del tallo. Veintitrés aislamientos de este hongo, provenientes de diferentes zonas geográficas de la provincia de Buenos Aires, fueron caracterizados morfológica y genéticamente. Los criterios morfológicos fueron tipo y color de micelio; formación del teleomorfo y/o del anamorfo. La identificación molecular fue llevada a cabo utilizando una técnica de restricción de fragmentos de amplificación (PCR-RFLP de la región ITS de ADN ribosomal. Adicionalmente, los productos de amplificación fueron secuenciados y comparados con la información de bancos de datos. Los aislamientos presentaron características morfológicas y patogénicas propias de la variedad, y los patrones de restricción con la enzima Alu I fueron concordantes con la identificación morfológica y con la información de secuencias disponibles. Las reconstrucciones filogenéticas apoyan la idea de que D. meridionalis y D. caulivora son entidades biológicamente aisladas. Los resultados obtenidos confirmaron la utilidad del uso del método de PCR-RFLP para la identificación precisa y rápida de D. caulivora. Por sus características, este método puede ser implementado para análisis de rutina en laboratorios de pequeña y mediana escala.AbstractDiaporthe/Phomopsis is an important group of soybean pathogens. Diaporthe phaseolorum var. caulivora is one of the causal agents of stem canker. Twenty three isolates from different regions from the Province of Buenos Aires were morphologically and genetically characterized and assigned to different taxa within the Diaporthe/Phomopsis complex; diagnostic morphological traits were: mycelium type and color, teleomorph/anamorph occurrence. Molecular characterization was carried out using RFLP analyses of PCR-amplified DNA (PCRRFLP for the

  10. Causality in Classical Physics

    Indian Academy of Sciences (India)

    IAS Admin

    Classical physics encompasses the study of phys- ical phenomena which range from local (a point) to nonlocal (a region) in space and/or time. We discuss the concept of spatial and temporal non- locality. However, one of the likely implications pertaining to nonlocality is non-causality. We study causality in the context of ...

  11. Regression to Causality

    DEFF Research Database (Denmark)

    Bordacconi, Mats Joe; Larsen, Martin Vinæs

    2014-01-01

    Humans are fundamentally primed for making causal attributions based on correlations. This implies that researchers must be careful to present their results in a manner that inhibits unwarranted causal attribution. In this paper, we present the results of an experiment that suggests regression...... models – one of the primary vehicles for analyzing statistical results in political science – encourage causal interpretation. Specifically, we demonstrate that presenting observational results in a regression model, rather than as a simple comparison of means, makes causal interpretation of the results...... of equivalent results presented as either regression models or as a test of two sample means. Our experiment shows that the subjects who were presented with results as estimates from a regression model were more inclined to interpret these results causally. Our experiment implies that scholars using regression...

  12. Agency, time and causality

    Directory of Open Access Journals (Sweden)

    Thomas eWidlok

    2014-11-01

    Full Text Available Cognitive Scientists interested in causal cognition increasingly search for evidence from non-WEIRD people but find only very few cross-cultural studies that specifically target causal cognition. This article suggests how information about causality can be retrieved from ethnographic monographs, specifically from ethnographies that discuss agency and concepts of time. Many apparent cultural differences with regard to causal cognition dissolve when cultural extensions of agency and personhood to non-humans are taken into account. At the same time considerable variability remains when we include notions of time, linearity and sequence. The article focuses on ethnographic case studies from Africa but provides a more general perspective on the role of ethnography in research on the diversity and universality of causal cognition.

  13. Non-Causal Computation

    Directory of Open Access Journals (Sweden)

    Ämin Baumeler

    2017-07-01

    Full Text Available Computation models such as circuits describe sequences of computation steps that are carried out one after the other. In other words, algorithm design is traditionally subject to the restriction imposed by a fixed causal order. We address a novel computing paradigm beyond quantum computing, replacing this assumption by mere logical consistency: We study non-causal circuits, where a fixed time structure within a gate is locally assumed whilst the global causal structure between the gates is dropped. We present examples of logically consistent non-causal circuits outperforming all causal ones; they imply that suppressing loops entirely is more restrictive than just avoiding the contradictions they can give rise to. That fact is already known for correlations as well as for communication, and we here extend it to computation.

  14. INDUCCIÓN DE POLIFENOLOXIDASA EN FRUTOS DE LULO (Solanum quitoense COMO RESPUESTA A LA INFECCIÓN CON Colletotrichum acutatum Polyphenol Oxidase Induction in Lulo Fruits (Solanum quitoense Infected by Colletotrichum acutatum

    Directory of Open Access Journals (Sweden)

    OBRADITH CAICEDO O

    Full Text Available Se evaluó la actividad polifenoloxidasa (PFO en corteza de frutos de lulo con el fin de determinar su participación en respuestas hacia el patógeno Colletotrichum acutatum, causante de la antracnosis. Se estudiaron condiciones para la adecuada extracción de esta enzima, encontrándose que con buffer fosfatos 100 mM pH 7, 1% SDS y 1% PVPP se logran las mayores actividades. Se determinaron como mejores parámetros para medir la actividad de la enzima extraída, sustrato catecol 40 mM, pH 7,0, 23 °C y 30 µL de extracto. Para determinar su posible inducción en la interacción con el patógeno, se realizó un ensayo in vivo usando frutos verdes, pintones y maduros, inoculados con el hongo o con agua estéril. A nueve tiempos postinoculación se determinó la actividad PFO encontrándose que hay una respuesta diferencial con el tiempo y la madurez de los frutos y por efecto del patógeno. Se obtuvo aumento de actividad en lulos verdes a 48, 96 y 144 horas postinoculación (hpi y en maduros a la mayoría de los tiempos evaluados, siendo éste estado en el que se presentó la respuesta más notable de inducción. En pintones aumentó solo a 72 y 144 hpi. Los mayores valores se registraron en general para frutos en estado verde. Los frutos respondieron al estrés ocasionado por la herida activando también esta enzima. La inducción de actividad se presentó a tiempos más rápidos en los frutos menos afectados por la enfermedad (verdes y maduros, por lo que se puede postular una relación positiva entre inducción de PFO y respuesta de tolerancia a la antracnosis.Polyphenol oxidase (PFO activity induction was evaluated in lulo fruits to determine the role of this enzyme in resistance responses towards the pathogen Colletotrichum acutatum which causes anthracnose disease. We studied the experimental conditions to obtain the enzyme, using lulo peel, and found that extraction with phosphates buffer 100 mM pH 7, 1% SDS y 1% PVPP showed higher

  15. Causal Networks or Causal Islands? The Representation of Mechanisms and the Transitivity of Causal Judgment

    Science.gov (United States)

    Johnson, Samuel G. B.; Ahn, Woo-kyoung

    2015-01-01

    Knowledge of mechanisms is critical for causal reasoning. We contrasted two possible organizations of causal knowledge--an interconnected causal "network," where events are causally connected without any boundaries delineating discrete mechanisms; or a set of disparate mechanisms--causal "islands"--such that events in different…

  16. Antagonistic Activities of Bacillus spp. Strains Isolated from Tidal Flat Sediment Towards Anthracnose Pathogens Colletotrichum acutatum and C. gloeosporioides in South Korea

    Directory of Open Access Journals (Sweden)

    Joon-Hee Han

    2015-06-01

    Full Text Available Anthracnose is a fungal disease caused by Colletotrichum species that is detrimental to numerous plant species. Anthracnose control with fungicides has both human health and environmental safety implications. Despite increasing public concerns, fungicide use will continue in the absence of viable alternatives. There have been relatively less efforts to search antagonistic bacteria from mudflats harboring microbial diversity. A total of 420 bacterial strains were isolated from mudflats near the western sea of South Korea. Five bacterial strains, LB01, LB14, HM03, HM17, and LB15, were characterized as having antifungal properties in the presence of C. acutatum and C. gloeosporioides. The three Bacillus atrophaeus strains, LB14, HM03, and HM17, produced large quantities of chitinase and protease enzymes, whereas the B. amyloliquefaciens strain LB01 produced protease and cellulase enzymes. Two important antagonistic traits, siderophore production and solubilization of insoluble phosphate, were observed in the three B. atrophaeus strains. Analyses of disease suppression revealed that LB14 was most effective for suppressing the incidence of anthracnose symptoms on pepper fruits. LB14 produced antagonistic compounds and suppressed conidial germination of C. acutatum and C. gloeosporioides. The results from the present study will provide a basis for developing a reliable alternative to fungicides for anthracnose control.

  17. Quantum Causal Graph Dynamics

    CERN Document Server

    Arrighi, Pablo

    2016-01-01

    Consider a graph having quantum systems lying at each node. Suppose that the whole thing evolves in discrete time steps, according to a global, unitary causal operator. By causal we mean that information can only propagate at a bounded speed, with respect to the distance given by the graph. Suppose, moreover, that the graph itself is subject to the evolution, and may be driven to be in a quantum superposition of graphs---in accordance to the superposition principle. We show that these unitary causal operators must decompose as a finite-depth circuit of local unitary gates. This unifies a result on Quantum Cellular Automata with another on Reversible Causal Graph Dynamics. Along the way we formalize a notion of causality which is valid in the context of quantum superpositions of time-varying graphs, and has a number of good properties. Keywords: Quantum Lattice Gas Automata, Block-representation, Curtis-Hedlund-Lyndon, No-signalling, Localizability, Quantum Gravity, Quantum Graphity, Causal Dynamical Triangula...

  18. Causality discovery technology

    Science.gov (United States)

    Chen, M.; Ertl, T.; Jirotka, M.; Trefethen, A.; Schmidt, A.; Coecke, B.; Bañares-Alcántara, R.

    2012-11-01

    Causality is the fabric of our dynamic world. We all make frequent attempts to reason causation relationships of everyday events (e.g., what was the cause of my headache, or what has upset Alice?). We attempt to manage causality all the time through planning and scheduling. The greatest scientific discoveries are usually about causality (e.g., Newton found the cause for an apple to fall, and Darwin discovered natural selection). Meanwhile, we continue to seek a comprehensive understanding about the causes of numerous complex phenomena, such as social divisions, economic crisis, global warming, home-grown terrorism, etc. Humans analyse and reason causality based on observation, experimentation and acquired a priori knowledge. Today's technologies enable us to make observations and carry out experiments in an unprecedented scale that has created data mountains everywhere. Whereas there are exciting opportunities to discover new causation relationships, there are also unparalleled challenges to benefit from such data mountains. In this article, we present a case for developing a new piece of ICT, called Causality Discovery Technology. We reason about the necessity, feasibility and potential impact of such a technology.

  19. Causal symmetric spaces

    CERN Document Server

    Olafsson, Gestur; Helgason, Sigurdur

    1996-01-01

    This book is intended to introduce researchers and graduate students to the concepts of causal symmetric spaces. To date, results of recent studies considered standard by specialists have not been widely published. This book seeks to bring this information to students and researchers in geometry and analysis on causal symmetric spaces.Includes the newest results in harmonic analysis including Spherical functions on ordered symmetric space and the holmorphic discrete series and Hardy spaces on compactly casual symmetric spacesDeals with the infinitesimal situation, coverings of symmetric spaces, classification of causal symmetric pairs and invariant cone fieldsPresents basic geometric properties of semi-simple symmetric spacesIncludes appendices on Lie algebras and Lie groups, Bounded symmetric domains (Cayley transforms), Antiholomorphic Involutions on Bounded Domains and Para-Hermitian Symmetric Spaces

  20. Causal inference in econometrics

    CERN Document Server

    Kreinovich, Vladik; Sriboonchitta, Songsak

    2016-01-01

    This book is devoted to the analysis of causal inference which is one of the most difficult tasks in data analysis: when two phenomena are observed to be related, it is often difficult to decide whether one of them causally influences the other one, or whether these two phenomena have a common cause. This analysis is the main focus of this volume. To get a good understanding of the causal inference, it is important to have models of economic phenomena which are as accurate as possible. Because of this need, this volume also contains papers that use non-traditional economic models, such as fuzzy models and models obtained by using neural networks and data mining techniques. It also contains papers that apply different econometric models to analyze real-life economic dependencies.

  1. Causality in Europeanization Research

    DEFF Research Database (Denmark)

    Lynggaard, Kennet

    2012-01-01

    to develop discursive institutional analytical frameworks and something that comes close to the formulation of hypothesis on the effects of European Union (EU) policies and institutions on domestic change. Even if these efforts so far do not necessarily amount to substantive theories or claims of causality...

  2. Understanding Causal Coherence Relations

    NARCIS (Netherlands)

    Mulder, G.

    2008-01-01

    The research reported in this dissertation focuses on the cognitive processes and representations involved in understanding causal coherence relations in text. Coherence relations are the meaning relations between the information units in the text, such as Cause-Consequence. These relations can be

  3. Explaining through causal mechanisms

    NARCIS (Netherlands)

    Biesbroek, Robbert; Dupuis, Johann; Wellstead, Adam

    2017-01-01

    This paper synthesizes and builds on recent critiques of the resilience literature; namely that the field has largely been unsuccessful in capturing the complexity of governance processes, in particular cause–effects relationships. We demonstrate that absence of a causal model is reflected in the

  4. Twin Paradox and Causality

    OpenAIRE

    Grandou, T.; Rubin, J.L.

    2007-01-01

    After pointing out the historical avatar at the origin of a would be twin or clock paradox, we argue that, at least on a local scale, the (re-qualified) paradox is but a necessary consequence of the sole principle of causality.

  5. Inducción de polifenoloxidasa en frutos de lulo (Solanum quitoense como respuesta a la infección con Colletotrichum acutatum Polyphenol Oxidase Induction in Lulo Fruits (Solanum quitoense Infected by Colletotrichum acutatum

    Directory of Open Access Journals (Sweden)

    Higuera Blanca L.

    2007-12-01

    Full Text Available Se evaluó la actividad polifenoloxidasa (PFO en corteza de frutos de lulo con el fin de determinar su participación en respuestas hacia el patógeno Colletotrichum acutatum, causante de la antracnosis. Se estudiaron condiciones para la adecuada extracción de esta enzima, encontrándose que con buffer fosfatos 100 mM pH 7, 1% SDS y 1% PVPP se logran las mayores actividades. Se determinaron como mejores parámetros para medir la actividad de la enzima extraída, sustrato catecol 40 mM, pH 7,0, 23 °C y 30 µL de extracto. Para determinar su posible inducción en la interacción con el patógeno, se realizó un ensayo in vivo usando frutos verdes, pintones y maduros, inoculados con el hongo o con agua estéril. A nueve tiempos postinoculación se determinó la actividad PFO encontrándose que hay una respuesta diferencial con el tiempo y la madurez de los frutos y por efecto del patógeno. Se obtuvo aumento de actividad en lulos verdes a 48, 96 y 144 horas postinoculación (hpi y en maduros a la mayoría de los tiempos evaluados, siendo éste estado en el que se presentó la respuesta más notable de inducción. En pintones aumentó solo a 72 y 144 hpi. Los mayores valores se registraron en general para frutos en estado verde. Los frutos respondieron al estrés ocasionado por la herida activando también esta enzima. La inducción de actividad se presentó a tiempos más rápidos en los frutos menos afectados por la enfermedad (verdes y maduros, por lo que se puede postular una relación positiva entre inducción de PFO y respuesta de tolerancia a la antracnosis.Polyphenol oxidase (PFO activity induction was evaluated in lulo fruits to determine the role of this enzyme in resistance responses towards the pathogen Colletotrichum acutatum which causes anthracnose disease. We studied the experimental conditions to obtain the enzyme, using lulo peel, and found that extraction with phosphates buffer 100 mM pH 7, 1

  6. Osmotic dehydration of apple slices using a sucrose/CaCl2 combination to control spoilage caused by Botrytis cinerea, Colletotrichum acutatum, and Penicillium expansum.

    Science.gov (United States)

    Chardonnet, C O; Sams, C E; Conway, W S; Mount, J R; Draughon, F A

    2001-09-01

    The efficacy of sucrose combined with CaCl2 during osmotic dehydration (OD) was tested for the control of Botrytis cinerea, Colletotrichum acutatum, and Penicillium expansum growth on lightly processed apple slices. The objective of this work was to determine whether the addition of CaCl2 in the osmotic solutions would limit the proliferation of fungal decay organisms. Slices were submitted to OD for 1 h at 25 degrees C in solutions containing 5 to 65% sucrose. Calcium chloride was added to a similar set of sucrose solutions at 0 to 8%. Control slices were made of untreated slices, and slices were processed in water. The mass ratio of the slices did not vary when fruit pieces were processed in solutions containing 5 to 65% sucrose. These slices showed a high susceptibility to spoilage compared to the control slices not submitted to OD: a significant twofold and 60% increase in decay area caused by B. cinerea and P. expansum, respectively, was observed when slices were processed in 50% sucrose/0% CaCl2; C. acutatum showed a significant 50% increase in decay area when slices were processed in 20% sucrose/0% CaCl2. Calcium uptake was significantly increased when slices were processed in CaCl2 solutions, and the highest Ca content was observed when processed in 8% CaCl2, reaching 40 times that of the control slices processed in water. Calcium-treated slices were less susceptible to spoilage by all three pathogens, and the most effective combination in reducing apple slice spoilage was 20 to 30% sucrose combined with 2% CaCl2.

  7. Optimal causal inference: estimating stored information and approximating causal architecture.

    Science.gov (United States)

    Still, Susanne; Crutchfield, James P; Ellison, Christopher J

    2010-09-01

    We introduce an approach to inferring the causal architecture of stochastic dynamical systems that extends rate-distortion theory to use causal shielding--a natural principle of learning. We study two distinct cases of causal inference: optimal causal filtering and optimal causal estimation. Filtering corresponds to the ideal case in which the probability distribution of measurement sequences is known, giving a principled method to approximate a system's causal structure at a desired level of representation. We show that in the limit in which a model-complexity constraint is relaxed, filtering finds the exact causal architecture of a stochastic dynamical system, known as the causal-state partition. From this, one can estimate the amount of historical information the process stores. More generally, causal filtering finds a graded model-complexity hierarchy of approximations to the causal architecture. Abrupt changes in the hierarchy, as a function of approximation, capture distinct scales of structural organization. For nonideal cases with finite data, we show how the correct number of the underlying causal states can be found by optimal causal estimation. A previously derived model-complexity control term allows us to correct for the effect of statistical fluctuations in probability estimates and thereby avoid overfitting.

  8. Information causality and noisy computations

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Li-Yi [Department of Physics, Chung Yuan Christian University, Chung-li 32023, Taiwan (China); Yu, I-Ching; Lin, Feng-Li [Department of Physics, National Taiwan Normal University, Taipei 116, Taiwan (China)

    2011-10-15

    We reformulate the information causality in a more general framework by adopting the results of signal propagation and computation in a noisy circuit. In our framework, the information causality leads to a broad class of Tsirelson inequalities. This fact allows us to subject information causality to experimental scrutiny. A no-go theorem for reliable nonlocal computation is also derived. Information causality prevents any physical circuit from performing reliable computations.

  9. Revisiting Causality in Markov Chains

    CERN Document Server

    Shojaee, Abbas

    2016-01-01

    Identifying causal relationships is a key premise of scientific research. The growth of observational data in different disciplines along with the availability of machine learning methods offers the possibility of using an empirical approach to identifying potential causal relationships, to deepen our understandings of causal behavior and to build theories accordingly. Conventional methods of causality inference from observational data require a considerable length of time series data to capture cause-effect relationship. We find that potential causal relationships can be inferred from the composition of one step transition rates to and from an event. Also known as Markov chain, one step transition rates are a commonly available resource in different scientific disciplines. Here we introduce a simple, effective and computationally efficient method that we termed 'Causality Inference using Composition of Transitions CICT' to reveal causal structure with high accuracy. We characterize the differences in causes,...

  10. Quantum information causality.

    Science.gov (United States)

    Pitalúa-García, Damián

    2013-05-24

    How much information can a transmitted physical system fundamentally communicate? We introduce the principle of quantum information causality, which states the maximum amount of quantum information that a quantum system can communicate as a function of its dimension, independently of any previously shared quantum physical resources. We present a new quantum information task, whose success probability is upper bounded by the new principle, and show that an optimal strategy to perform it combines the quantum teleportation and superdense coding protocols with a task that has classical inputs.

  11. Causal Entropic Forces

    Science.gov (United States)

    Wissner-Gross, A. D.; Freer, C. E.

    2013-04-01

    Recent advances in fields ranging from cosmology to computer science have hinted at a possible deep connection between intelligence and entropy maximization, but no formal physical relationship between them has yet been established. Here, we explicitly propose a first step toward such a relationship in the form of a causal generalization of entropic forces that we find can cause two defining behaviors of the human “cognitive niche”—tool use and social cooperation—to spontaneously emerge in simple physical systems. Our results suggest a potentially general thermodynamic model of adaptive behavior as a nonequilibrium process in open systems.

  12. Entropy of Causal Horizons

    CERN Document Server

    Howard, Eric M

    2016-01-01

    We analyze spacetimes with horizons and study the thermodynamic aspects of causal horizons, suggesting that the resemblance between gravitational and thermodynamic systems has a deeper quantum mechanical origin. We find that the observer dependence of such horizons is a direct consequence of associating a temperature and entropy to a spacetime. The geometrical picture of a horizon acting as a one-way membrane for information flow can be accepted as a natural interpretation of assigning a quantum field theory to a spacetime with boundary, ultimately leading to a close connection with thermodynamics.

  13. Causal inference based on counterfactuals

    Directory of Open Access Journals (Sweden)

    Höfler M

    2005-09-01

    Full Text Available Abstract Background The counterfactual or potential outcome model has become increasingly standard for causal inference in epidemiological and medical studies. Discussion This paper provides an overview on the counterfactual and related approaches. A variety of conceptual as well as practical issues when estimating causal effects are reviewed. These include causal interactions, imperfect experiments, adjustment for confounding, time-varying exposures, competing risks and the probability of causation. It is argued that the counterfactual model of causal effects captures the main aspects of causality in health sciences and relates to many statistical procedures. Summary Counterfactuals are the basis of causal inference in medicine and epidemiology. Nevertheless, the estimation of counterfactual differences pose several difficulties, primarily in observational studies. These problems, however, reflect fundamental barriers only when learning from observations, and this does not invalidate the counterfactual concept.

  14. Causality & holographic entanglement entropy

    Energy Technology Data Exchange (ETDEWEB)

    Headrick, Matthew [Martin Fisher School of Physics, Brandeis University, MS 057, 415 South Street, Waltham, MA 02454 (United States); Hubeny, Veronika E. [Centre for Particle Theory & Department of Mathematical Sciences,Science Laboratories, South Road, Durham DH1 3LE (United Kingdom); Lawrence, Albion [Martin Fisher School of Physics, Brandeis University, MS 057, 415 South Street, Waltham, MA 02454 (United States); Rangamani, Mukund [Centre for Particle Theory & Department of Mathematical Sciences,Science Laboratories, South Road, Durham DH1 3LE (United Kingdom)

    2014-12-29

    We identify conditions for the entanglement entropy as a function of spatial region to be compatible with causality in an arbitrary relativistic quantum field theory. We then prove that the covariant holographic entanglement entropy prescription (which relates entanglement entropy of a given spatial region on the boundary to the area of a certain extremal surface in the bulk) obeys these conditions, as long as the bulk obeys the null energy condition. While necessary for the validity of the prescription, this consistency requirement is quite nontrivial from the bulk standpoint, and therefore provides important additional evidence for the prescription. In the process, we introduce a codimension-zero bulk region, named the entanglement wedge, naturally associated with the given boundary spatial region. We propose that the entanglement wedge is the most natural bulk region corresponding to the boundary reduced density matrix.

  15. The Cosmic Causal Mass

    Directory of Open Access Journals (Sweden)

    Simen Braeck

    2017-04-01

    Full Text Available In order to provide a better understanding of rotating universe models, and in particular the Gödel universe, we discuss the relationship between cosmic rotation and perfect inertial dragging. In this connection, the concept of causal mass is defined in a cosmological context, and discussed in relation to the cosmic inertial dragging effect. Then, we calculate the mass inside the particle horizon of the flat ΛCDM-model integrated along the past light cone. The calculation shows that the Schwarzschild radius of this mass is around three times the radius of the particle horizon. This indicates that there is close to perfect inertial dragging in our universe. Hence, the calculation provides an explanation for the observation that the swinging plane of a Foucault pendulum follows the stars.

  16. Causality Statistical Perspectives and Applications

    CERN Document Server

    Berzuini, Carlo; Bernardinell, Luisa

    2012-01-01

    A state of the art volume on statistical causality Causality: Statistical Perspectives and Applications presents a wide-ranging collection of seminal contributions by renowned experts in the field, providing a thorough treatment of all aspects of statistical causality. It covers the various formalisms in current use, methods for applying them to specific problems, and the special requirements of a range of examples from medicine, biology and economics to political science. This book:Provides a clear account and comparison of formal languages, concepts and models for statistical causality. Addr

  17. Expert Causal Reasoning and Explanation.

    Science.gov (United States)

    Kuipers, Benjamin

    The relationship between cognitive psychologists and researchers in artificial intelligence carries substantial benefits for both. An ongoing investigation in causal reasoning in medical problem solving systems illustrates this interaction. This paper traces a dialectic of sorts in which three different types of causal resaoning for medical…

  18. Introduction to causal dynamical triangulations

    DEFF Research Database (Denmark)

    Görlich, Andrzej

    2013-01-01

    The method of causal dynamical triangulations is a non-perturbative and background-independent approach to quantum theory of gravity. In this review we present recent results obtained within the four dimensional model of causal dynamical triangulations. We describe the phase structure of the mode...

  19. Causal Inference and Developmental Psychology

    Science.gov (United States)

    Foster, E. Michael

    2010-01-01

    Causal inference is of central importance to developmental psychology. Many key questions in the field revolve around improving the lives of children and their families. These include identifying risk factors that if manipulated in some way would foster child development. Such a task inherently involves causal inference: One wants to know whether…

  20. Re-thinking local causality

    NARCIS (Netherlands)

    Friederich, Simon

    There is widespread belief in a tension between quantum theory and special relativity, motivated by the idea that quantum theory violates J. S. Bell's criterion of local causality, which is meant to implement the causal structure of relativistic space-time. This paper argues that if one takes the

  1. Paradoxical Behavior of Granger Causality

    Science.gov (United States)

    Witt, Annette; Battaglia, Demian; Gail, Alexander

    2013-03-01

    Granger causality is a standard tool for the description of directed interaction of network components and is popular in many scientific fields including econometrics, neuroscience and climate science. For time series that can be modeled as bivariate auto-regressive processes we analytically derive an expression for spectrally decomposed Granger Causality (SDGC) and show that this quantity depends only on two out of four groups of model parameters. Then we present examples of such processes whose SDGC expose paradoxical behavior in the sense that causality is high for frequency ranges with low spectral power. For avoiding misinterpretations of Granger causality analysis we propose to complement it by partial spectral analysis. Our findings are illustrated by an example from brain electrophysiology. Finally, we draw implications for the conventional definition of Granger causality. Bernstein Center for Computational Neuroscience Goettingen

  2. Clear message for causality

    Energy Technology Data Exchange (ETDEWEB)

    Steinberg, Aephraim M. [Institute for Experimental Physics, University of Vienna, Vienna (Austria)

    2003-12-01

    Experiment confirms that information cannot be transmitted faster than the speed of light. Ever since Einstein stated that nothing can travel faster than light, physicists have delighted in finding exceptions. One after another, observations of such 'superluminal' propagation have been made. However, while some image or pattern- such as the motion of a spotlight projected on a distant wall - might have appeared to travel faster than light, it seemed that there was no way to use the superluminal effect to transmit energy or information. In recent years, the superluminal propagation of light pulses through certain media has led to renewed controversy. In 1995, for example, Guenther Nimtz of the University of Cologne encoded Mozart's 40th Symphony on a microwave beam, which he claimed to have transmitted at a speed faster than light. Others maintain that such a violation of Einstein's speed limit would wreak havoc on our most fundamental ideas about causality, allowing an effect to precede its cause. Relativity teaches us that sending a signal faster than light would be equivalent to sending it backwards in time. (U.K.)

  3. Multiscale Granger causality

    Science.gov (United States)

    Faes, Luca; Nollo, Giandomenico; Stramaglia, Sebastiano; Marinazzo, Daniele

    2017-10-01

    In the study of complex physical and biological systems represented by multivariate stochastic processes, an issue of great relevance is the description of the system dynamics spanning multiple temporal scales. While methods to assess the dynamic complexity of individual processes at different time scales are well established, multiscale analysis of directed interactions has never been formalized theoretically, and empirical evaluations are complicated by practical issues such as filtering and downsampling. Here we extend the very popular measure of Granger causality (GC), a prominent tool for assessing directed lagged interactions between joint processes, to quantify information transfer across multiple time scales. We show that the multiscale processing of a vector autoregressive (AR) process introduces a moving average (MA) component, and describe how to represent the resulting ARMA process using state space (SS) models and to combine the SS model parameters for computing exact GC values at arbitrarily large time scales. We exploit the theoretical formulation to identify peculiar features of multiscale GC in basic AR processes, and demonstrate with numerical simulations the much larger estimation accuracy of the SS approach compared to pure AR modeling of filtered and downsampled data. The improved computational reliability is exploited to disclose meaningful multiscale patterns of information transfer between global temperature and carbon dioxide concentration time series, both in paleoclimate and in recent years.

  4. History, causality, and sexology.

    Science.gov (United States)

    Money, John

    2003-08-01

    In 1896, Krafft-Ebing published Psychopathia Sexualis. Popularly defined as hereditary weakness or taintedness in the family pedigree, degeneracy was called upon as a causal explanation for perversions of the sexual instinct. Although Krafft-Ebing accepted Karl Ulrichs proposal that homosexuality could be innate and probably located in the brain, he paid little attention to neuropathological sexology. Alfred Binet challenged Krafft-Ebing's orthodoxy by explaining fetishism in terms of associative learning, to which Krafft-Ebing's response was that only those with a hereditary taint would be vulnerable. Thus did the venerable nature-nurture antithesis maintain its rhetoric, even to the present day. Krafft-Ebing died too soon to meet the Freudian challenge of endopsychic determinism, and too soon also to encounter the idea of a developmental multivariate outcome of what I have termed the lovemap. Like other brain maps, for example the languagemap, the lovemap requires an intact human brain in which to develop. The personalized content of the lovemap has access to the brain by way of the special senses.

  5. Causal Rasch models

    Directory of Open Access Journals (Sweden)

    A. Jackson Stenner

    2013-08-01

    Full Text Available Rasch’s unidimensional models for measurement show how to connect object measures (e.g., reader abilities, measurement mechanisms (e.g., machine-generated cloze reading items, and observational outcomes (e.g., counts correct on reading instruments. Substantive theory shows what interventions or manipulations to the measurement mechanism can be traded off against a change to the object measure to hold the observed outcome constant. A Rasch model integrated with a substantive theory dictates the form and substance of permissible interventions. Rasch analysis, absent construct theory and an associated specification equation, is a black box in which understanding may be more illusory than not. Finally, the quantitative hypothesis can be tested by comparing theory-based trade-off relations with observed trade-off relations. Only quantitative variables (as measured support such trade-offs. Note that to test the quantitative hypothesis requires more than manipulation of the algebraic equivalencies in the Rasch model or descriptively fitting data to the model. A causal Rasch model involves experimental intervention/manipulation on either reader ability or text complexity or a conjoint intervention on both simultaneously to yield a successful prediction of the resultant observed outcome (count correct. We conjecture that when this type of manipulation is introduced for individual reader text encounters and model predictions are consistent with observations, the quantitative hypothesis is sustained.

  6. Neural Correlates of Causal Power Judgments

    Directory of Open Access Journals (Sweden)

    Denise Dellarosa Cummins

    2014-12-01

    Full Text Available Causal inference is a fundamental component of cognition and perception. Probabilistic theories of causal judgment (most notably causal Bayes networks derive causal judgments using metrics that integrate contingency information. But human estimates typically diverge from these normative predictions. This is because human causal power judgments are typically strongly influenced by beliefs concerning underlying causal mechanisms, and because of the way knowledge is retrieved from human memory during the judgment process. Neuroimaging studies indicate that the brain distinguishes causal events from mere covariation, and between perceived and inferred causality. Areas involved in error prediction are also activated, implying automatic activation of possible exception cases during causal decision-making.

  7. Xanthomonas campestris pv. campestris race 1 is the main causal ...

    African Journals Online (AJOL)

    Severe outbreaks of bacterial black rot caused by Xanthomonas campestris pv. campestris (Xcc) were observed in Brassica production fields of Southern Mozambique. The causal agent of the disease in the Mahotas and Chòkwé districts was identified and characterised. In total, 83 Xanthomonas-like strains were isolated ...

  8. Clarity and causality needed in claims about Big Gods.

    Science.gov (United States)

    Watts, Joseph; Bulbulia, Joseph; Gray, Russell D; Atkinson, Quentin D

    2016-01-01

    We welcome Norenzayan et al.'s claim that the prosocial effects of beliefs in supernatural agents extend beyond Big Gods. To date, however, supporting evidence has focused on the Abrahamic Big God, making generalisations difficult. We discuss a recent study that highlights the need for clarity about the causal path by which supernatural beliefs affect the evolution of big societies.

  9. Discrete causal theory emergent spacetime and the causal metric hypothesis

    CERN Document Server

    Dribus, Benjamin F

    2017-01-01

    This book evaluates and suggests potentially critical improvements to causal set theory, one of the best-motivated approaches to the outstanding problems of fundamental physics. Spacetime structure is of central importance to physics beyond general relativity and the standard model. The causal metric hypothesis treats causal relations as the basis of this structure. The book develops the consequences of this hypothesis under the assumption of a fundamental scale, with smooth spacetime geometry viewed as emergent. This approach resembles causal set theory, but differs in important ways; for example, the relative viewpoint, emphasizing relations between pairs of events, and relationships between pairs of histories, is central. The book culminates in a dynamical law for quantum spacetime, derived via generalized path summation.

  10. Functional equations with causal operators

    CERN Document Server

    Corduneanu, C

    2003-01-01

    Functional equations encompass most of the equations used in applied science and engineering: ordinary differential equations, integral equations of the Volterra type, equations with delayed argument, and integro-differential equations of the Volterra type. The basic theory of functional equations includes functional differential equations with causal operators. Functional Equations with Causal Operators explains the connection between equations with causal operators and the classical types of functional equations encountered by mathematicians and engineers. It details the fundamentals of linear equations and stability theory and provides several applications and examples.

  11. Expresión del gen chit42 de Trichoderma harzianum en plantas de fresa: obtención de plantas de fresa con mayor resistencia a la infección por Colletrotrichum acutatum

    OpenAIRE

    Caballero, J.L.; Muñoz-Blanco, Juan

    2009-01-01

    La antracnosis, causada por diferentes especies del hongo Colletotrichum, origina importantes pérdidas de producción en el cultivo de la fresa, un cultivo de gran interés agrícola en Andalucía, que aporta el 92.01% de la producción nacional y que, a su vez, genera más del 10% de la producción mundial total. C. acutatum está considerado un organismo de cuarentena en Europa (Directiva EC 77/93, Real Decreto 2071/1993). No se conocen variedades de fresa totalmente resistentes a C. ac...

  12. Causal inference in multisensory perception

    National Research Council Canada - National Science Library

    Körding, Konrad P; Beierholm, Ulrik; Ma, Wei Ji; Quartz, Steven; Tenenbaum, Joshua B; Shams, Ladan

    2007-01-01

    .... Here we use multisensory cue combination to study causal inference in perception. We formulate an ideal-observer model that infers whether two sensory cues originate from the same location and that also estimates their location...

  13. Competence and performance in causal learning

    National Research Council Canada - National Science Library

    Waldmann, Michael R; Walker, Jessica M

    2005-01-01

    .... This reduction of causal induction to associative learning implies that learners are insensitive to important characteristics of causality, such as the inherent directionality between causes and effects...

  14. Different Kinds of Causality in Event Cognition

    Science.gov (United States)

    Radvansky, Gabriel A.; Tamplin, Andrea K.; Armendarez, Joseph; Thompson, Alexis N.

    2014-01-01

    Narrative memory is better for information that is more causally connected and occurs at event boundaries, such as a causal break. However, it is unclear whether there are common or distinct influences of causality. For the event boundaries that arise as a result of causal breaks, the events that follow may subsequently become more causally…

  15. Hierarchical organisation of causal graphs

    Energy Technology Data Exchange (ETDEWEB)

    Dziopa, P. [CEA Centre d`Etudes de la Vallee du Rhone, 30 - Marcoule (France). Dept. des Procedes de Retraitement; Gentil, S. [ENSIEG, 38 - Saint-Martin d`Heres (France)

    1993-12-31

    This paper deals with the design of a supervision system using a hierarchy of models formed by graphs, in which the variables are the nodes and the causal relations between the variables of the arcs. To obtain a representation of the variables evolutions which contains only the relevant features of their real evolutions, the causal relations are completed with qualitative transfer functions (QTFs) which produce roughly the behaviour of the classical transfer functions. Major improvements have been made in the building of the hierarchical organization. First, the basic variables of the uppermost level and the causal relations between them are chosen. The next graph is built by adding intermediary variables to the upper graph. When the undermost graph has been built, the transfer functions parameters corresponding to its causal relations are identified. The second task consists in the upwelling of the information from the undermost graph to the uppermost one. A fusion procedure of the causal relations has been designed to compute the QFTs relevant for each level. This procedure aims to reduce the number of parameters needed to represent an evolution at a high level of abstraction. These techniques have been applied to the hierarchical modelling of nuclear process. (authors). 8 refs., 12 figs.

  16. Causal reasoning with mental models

    Directory of Open Access Journals (Sweden)

    Sangeet eKhemlani

    2014-10-01

    Full Text Available This paper outlines the model-based theory of causal reasoning. It postulates that the core meanings of causal assertions are deterministic and refer to temporally-ordered sets of possibilities: A causes B to occur means that given A, B occurs, whereas A enables B to occur means that given A, it is possible for B to occur. The paper shows how mental models represent such assertions, and how these models underlie deductive, inductive, and abductive reasoning yielding explanations. It reviews evidence both to corroborate the theory and to account for phenomena sometimes taken to be incompatible with it. Finally, it reviews neuroscience evidence indicating that mental models for causal inference are implemented within lateral prefrontal cortex.

  17. Reasoning about causal relationships: Inferences on causal networks.

    Science.gov (United States)

    Rottman, Benjamin Margolin; Hastie, Reid

    2014-01-01

    Over the last decade, a normative framework for making causal inferences, Bayesian Probabilistic Causal Networks, has come to dominate psychological studies of inference based on causal relationships. The following causal networks-[X→Y→Z, X←Y→Z, X→Y←Z]-supply answers for questions like, "Suppose both X and Y occur, what is the probability Z occurs?" or "Suppose you intervene and make Y occur, what is the probability Z occurs?" In this review, we provide a tutorial for how normatively to calculate these inferences. Then, we systematically detail the results of behavioral studies comparing human qualitative and quantitative judgments to the normative calculations for many network structures and for several types of inferences on those networks. Overall, when the normative calculations imply that an inference should increase, judgments usually go up; when calculations imply a decrease, judgments usually go down. However, 2 systematic deviations appear. First, people's inferences violate the Markov assumption. For example, when inferring Z from the structure X→Y→Z, people think that X is relevant even when Y completely mediates the relationship between X and Z. Second, even when people's inferences are directionally consistent with the normative calculations, they are often not as sensitive to the parameters and the structure of the network as they should be. We conclude with a discussion of productive directions for future research. (PsycINFO Database Record (c) 2013 APA, all rights reserved).

  18. [Causal analysis approaches in epidemiology].

    Science.gov (United States)

    Dumas, O; Siroux, V; Le Moual, N; Varraso, R

    2014-02-01

    Epidemiological research is mostly based on observational studies. Whether such studies can provide evidence of causation remains discussed. Several causal analysis methods have been developed in epidemiology. This paper aims at presenting an overview of these methods: graphical models, path analysis and its extensions, and models based on the counterfactual approach, with a special emphasis on marginal structural models. Graphical approaches have been developed to allow synthetic representations of supposed causal relationships in a given problem. They serve as qualitative support in the study of causal relationships. The sufficient-component cause model has been developed to deal with the issue of multicausality raised by the emergence of chronic multifactorial diseases. Directed acyclic graphs are mostly used as a visual tool to identify possible confounding sources in a study. Structural equations models, the main extension of path analysis, combine a system of equations and a path diagram, representing a set of possible causal relationships. They allow quantifying direct and indirect effects in a general model in which several relationships can be tested simultaneously. Dynamic path analysis further takes into account the role of time. The counterfactual approach defines causality by comparing the observed event and the counterfactual event (the event that would have been observed if, contrary to the fact, the subject had received a different exposure than the one he actually received). This theoretical approach has shown limits of traditional methods to address some causality questions. In particular, in longitudinal studies, when there is time-varying confounding, classical methods (regressions) may be biased. Marginal structural models have been developed to address this issue. In conclusion, "causal models", though they were developed partly independently, are based on equivalent logical foundations. A crucial step in the application of these models is the

  19. Quantum theory and local causality

    CERN Document Server

    Hofer-Szabó, Gábor

    2018-01-01

    This book summarizes the results of research the authors have pursued in the past years on the problem of implementing Bell's notion of local causality in local physical theories and relating it to other important concepts and principles in the foundations of physics such as the Common Cause Principle, Bell's inequalities, the EPR (Einstein-Podolsky-Rosen) scenario, and various other locality and causality concepts. The book is intended for philosophers of science with an interest in the formal background of sciences, philosophers of physics and physicists working in foundation of physics.

  20. Causal feedbacks in climate change

    NARCIS (Netherlands)

    Nes, van E.H.; Scheffer, M.; Brovkin, V.; Lenton, T.M.; Ye, H.; Deyle, E.; Sugihara, G.

    2015-01-01

    The statistical association between temperature and greenhouse gases over glacial cycles is well documented1, but causality behind this correlation remains difficult to extract directly from the data. A time lag of CO2 behind Antarctic temperature—originally thought to hint at a driving role for

  1. Granger Causality and Unit Roots

    DEFF Research Database (Denmark)

    Rodríguez-Caballero, Carlos Vladimir; Ventosa-Santaulària, Daniel

    2014-01-01

    The asymptotic behavior of the Granger-causality test under stochastic nonstationarity is studied. Our results confirm that the inference drawn from the test is not reliable when the series are integrated to the first order. In the presence of deterministic components, the test statistic diverges...

  2. Entanglement, holography and causal diamonds

    NARCIS (Netherlands)

    de Boer, J.; Haehl, F.M.; Heller, M.P.; Myers, R.C.

    We argue that the degrees of freedom in a d-dimensional CFT can be reorganized in an insightful way by studying observables on the moduli space of causal diamonds (or equivalently, the space of pairs of timelike separated points). This 2d-dimensional space naturally captures some of the fundamental

  3. Sugarcane mosaic virus: The causal agent of mosaic disease on ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-10-19

    Oct 19, 2009 ... substrates BCIP/NBT used according to the manufacturer's instructions. Reverse Transcription-Polymerase Chain Reaction (RT-PCR). For nucleic acid extraction and Reverse Transcription-Polymerase. Chain Reaction (RT-PCR), the total nucleic acids were extracted from the frozen infected leaves from ...

  4. In vitro inhibition of pathogenic Verticillium dahliae, causal agent of ...

    African Journals Online (AJOL)

    SAM

    2014-08-13

    Aug 13, 2014 ... Trichoderma isolates under a dual culture condition on potato dextrose agar plate. The 33 ... in many countries, like USA, New Zealand, the Pacific .... levels of pathogenicity in potato. Trichoderma isolates were tested in vitro for their highest antagonistic ability over V. dahliae colony in dual culture.

  5. Diplodia natalensis , Pole Evans: a causal agent of citrus gummosis ...

    African Journals Online (AJOL)

    Isolations were made from the barks of gummosis-infected citrus trees from orchards of the University of Ghana Agricultural Research Station at Kade. The isolation media used were 1.5% water agar, 1.5% water agar + nystatin and 1.5% water agar + benomyl. Four isolates including Diplodia natalensis Pole Evans, ...

  6. Diplodia natalensis Pole Evans, the causal agent of citrus gummosis ...

    African Journals Online (AJOL)

    Four isolates including Diplodia natalensis Pole Evans, Fusarium solani Appel + Wr., and two other identified fungi were obtained. The two fungi were unidentified on Potato Dextrose Agar (PDA). When the isolates were tested for pathogenicity, only D. natalensis induced the disease symptoms in the inoculated ...

  7. Attributing causal agents to nationwide maps of forest disturbance

    Science.gov (United States)

    Gretchen G. Moisen; Todd A. Schroeder; Karen Schleeweis; Chris Toney; Warren B. Cohen; Samuel N. Goward

    2012-01-01

    Currently in its third phase, the North American Forest Dynamics (NAFD) project has launched nationwide processing of historic Landsat data to provide a comprehensive annual, wall-to-wall analysis of U.S. disturbance history over the last 30+ years. Because understanding the cause of disturbance is important to quantifying carbon dynamics, work is underway to attribute...

  8. Entanglement, holography and causal diamonds

    Energy Technology Data Exchange (ETDEWEB)

    Boer, Jan de [Institute of Physics, Universiteit van Amsterdam,Science Park 904, 1090 GL Amsterdam (Netherlands); Haehl, Felix M. [Centre for Particle Theory & Department of Mathematical Sciences, Durham University,South Road, Durham DH1 3LE (United Kingdom); Heller, Michal P.; Myers, Robert C. [Perimeter Institute for Theoretical Physics,31 Caroline Street North, Waterloo, Ontario N2L 2Y5 (Canada)

    2016-08-29

    We argue that the degrees of freedom in a d-dimensional CFT can be re-organized in an insightful way by studying observables on the moduli space of causal diamonds (or equivalently, the space of pairs of timelike separated points). This 2d-dimensional space naturally captures some of the fundamental nonlocality and causal structure inherent in the entanglement of CFT states. For any primary CFT operator, we construct an observable on this space, which is defined by smearing the associated one-point function over causal diamonds. Known examples of such quantities are the entanglement entropy of vacuum excitations and its higher spin generalizations. We show that in holographic CFTs, these observables are given by suitably defined integrals of dual bulk fields over the corresponding Ryu-Takayanagi minimal surfaces. Furthermore, we explain connections to the operator product expansion and the first law of entanglement entropy from this unifying point of view. We demonstrate that for small perturbations of the vacuum, our observables obey linear two-derivative equations of motion on the space of causal diamonds. In two dimensions, the latter is given by a product of two copies of a two-dimensional de Sitter space. For a class of universal states, we show that the entanglement entropy and its spin-three generalization obey nonlinear equations of motion with local interactions on this moduli space, which can be identified with Liouville and Toda equations, respectively. This suggests the possibility of extending the definition of our new observables beyond the linear level more generally and in such a way that they give rise to new dynamically interacting theories on the moduli space of causal diamonds. Various challenges one has to face in order to implement this idea are discussed.

  9. On the Causality and K-Causality between Measures

    Directory of Open Access Journals (Sweden)

    Tomasz Miller

    2017-03-01

    Full Text Available Drawing from the optimal transport theory adapted to the Lorentzian setting, we propose and study the extension of the Sorkin–Woolgar causal relation K + onto the space of Borel probability measures on a given spacetime. We show that it retains its fundamental properties of transitivity and closedness. Furthermore, we list and prove several characterizations of this relation, including the “measure-theoretic” analogue of the characterization of K + in terms of time functions.

  10. Causal Pixel Purity Index (PPI)

    Science.gov (United States)

    Wu, Chao-Cheng; Chang, Chein-I.

    2009-05-01

    Pixel Purity Index (PPI) has been widely used in endmember extraction. While it is available in ENVI software there are several interesting issues arising in its implementation. This paper re-invents the wheel by re-visiting the design rationale of the PPI and re-designing algorithms to implement PPI. More specifically, it develops the so-called Causal PPI (CPPI) which implements the PPI in a causal manner in the sense that the information used for data processing is only up to the data sample currently being visited. If the time required for computer processing is negligible, the CPPI actually becomes a real time PPI. The proposed CPPI can be implemented automatically and resolves the main issue of requiring human intervention to determine parameters.

  11. Identifying Causality from Alarm Observations

    DEFF Research Database (Denmark)

    Kirchhübel, Denis; Zhang, Xinxin; Lind, Morten

    on an abstracted model of the mass and energy flows in the system. The application of MFM for root cause analysis based alarm grouping has been demonstrated and can be extended to reason about the direction of causality considering the entirety of the alarms present in the system for more comprehensive decision...... and consequences. This extended analysis results in causal paths from likely root causes to tentative consequences, providing the operator with a comprehensive tool to not only identify but also rank the criticality of a large number of concurrent alarms in the system....... support. This contribution presents the foundation for combining the cause and consequence propagation of multiple observations from the system based on an MFM model. The proposed logical reasoning matches actually observed alarms to the propagation analysis in MFM to distinguish plausible causes...

  12. THE CAUSAL ANALYSIS / DIAGNOSIS DECISION ...

    Science.gov (United States)

    CADDIS is an on-line decision support system that helps investigators in the regions, states and tribes find, access, organize, use and share information to produce causal evaluations in aquatic systems. It is based on the US EPA's Stressor Identification process which is a formal method for identifying causes of impairments in aquatic systems. CADDIS 2007 increases access to relevant information useful for causal analysis and provides methods and tools that practitioners can use to analyze their own data. The new Candidate Cause section provides overviews of commonly encountered causes of impairments to aquatic systems: metals, sediments, nutrients, flow alteration, temperature, ionic strength, and low dissolved oxygen. CADDIS includes new Conceptual Models that illustrate the relationships from sources to stressors to biological effects. An Interactive Conceptual Model for phosphorus links the diagram with supporting literature citations. The new Analyzing Data section helps practitioners analyze their data sets and interpret and use those results as evidence within the USEPA causal assessment process. Downloadable tools include a graphical user interface statistical package (CADStat), and programs for use with the freeware R statistical package, and a Microsoft Excel template. These tools can be used to quantify associations between causes and biological impairments using innovative methods such as species-sensitivity distributions, biological inferenc

  13. The argumentative impact of causal relations

    DEFF Research Database (Denmark)

    Nielsen, Anne Ellerup

    1996-01-01

    such as causality, explanation and justification. In certain types of discourse, causal relations also imply an intentional element. This paper describes the way in which the semantic and pragmatic functions of causal markers can be accounted for in terms of linguistic and rhetorical theories of argumentation....

  14. On Fixed Points of Strictly Causal Functions

    Science.gov (United States)

    2013-04-08

    of the input. This is probably a folklore definition, but one that is universally accepted. After a careful, precise formalization of it, we show the...causal functions In this section, we formalize the folklore , but well established, notions of causality and strict causality, and through a series of

  15. Representing Personal Determinants in Causal Structures.

    Science.gov (United States)

    Bandura, Albert

    1984-01-01

    Responds to Staddon's critique of the author's earlier article and addresses issues raised by Staddon's (1984) alternative models of causality. The author argues that it is not the formalizability of causal processes that is the issue but whether cognitive determinants of behavior are reducible to past stimulus inputs in causal structures.…

  16. Exploring Individual Differences in Preschoolers' Causal Stance

    Science.gov (United States)

    Alvarez, Aubry; Booth, Amy E.

    2016-01-01

    Preschoolers, as a group, are highly attuned to causality, and this attunement is known to facilitate memory, learning, and problem solving. However, recent work reveals substantial individual variability in the strength of children's "causal stance," as demonstrated by their curiosity about and preference for new causal information. In…

  17. Causal knowledge and reasoning in decision making

    NARCIS (Netherlands)

    Hagmayer, Y.; Witteman, C.L.M.

    2017-01-01

    Normative causal decision theories argue that people should use their causal knowledge in decision making. Based on these ideas, we argue that causal knowledge and reasoning may support and thereby potentially improve decision making based on expected outcomes, narratives, and even cues. We will

  18. Does Causal Action Facilitate Causal Perception in Infants Younger than 6 Months of Age?

    Science.gov (United States)

    Rakison, David H.; Krogh, Lauren

    2012-01-01

    Previous research has established that infants are unable to perceive causality until 6 1/4 months of age. The current experiments examined whether infants' ability to engage in causal action could facilitate causal perception prior to this age. In Experiment 1, 4 1/2-month-olds were randomly assigned to engage in causal action experience via…

  19. Norms and customs: causally important or causally impotent?

    Science.gov (United States)

    Jones, Todd

    2010-01-01

    In this article, I argue that norms and customs, despite frequently being described as being causes of behavior in the social sciences and ordinary conversation, cannot really cause behavior. Terms like "norms" and the like seem to refer to philosophically disreputable disjunctive properties. More problematically, even if they do not, or even if there can be disjunctive properties after all, I argue that norms and customs still cannot cause behavior. The social sciences would be better off without referring to properties like norms and customs as if they could be causal.

  20. The key role of causal explanation in the climate change issue

    Directory of Open Access Journals (Sweden)

    Francesca Pongiglione

    2012-06-01

    Full Text Available The basis for adoption of pro-environment behaviour is the understanding of causal passages within climate dynamics. The understanding of the causes of climate change is necessary in order to be able to take mitigation actions  (the subject needs to be aware of his role as a causal agent. Conversely, the understanding of the consequences of climate change is essential in motivating action (the subject must be aware of the risks caused by it in order to prevent them. The case of ozone depletion confirms this view: the understanding of its causal dynamics played a determining role in people’s behavioural response.

  1. Experimental verification of an indefinite causal order.

    Science.gov (United States)

    Rubino, Giulia; Rozema, Lee A; Feix, Adrien; Araújo, Mateus; Zeuner, Jonas M; Procopio, Lorenzo M; Brukner, Časlav; Walther, Philip

    2017-03-01

    Investigating the role of causal order in quantum mechanics has recently revealed that the causal relations of events may not be a priori well defined in quantum theory. Although this has triggered a growing interest on the theoretical side, creating processes without a causal order is an experimental task. We report the first decisive demonstration of a process with an indefinite causal order. To do this, we quantify how incompatible our setup is with a definite causal order by measuring a "causal witness." This mathematical object incorporates a series of measurements that are designed to yield a certain outcome only if the process under examination is not consistent with any well-defined causal order. In our experiment, we perform a measurement in a superposition of causal orders-without destroying the coherence-to acquire information both inside and outside of a "causally nonordered process." Using this information, we experimentally determine a causal witness, demonstrating by almost 7 SDs that the experimentally implemented process does not have a definite causal order.

  2. Causal capture effects in chimpanzees (Pan troglodytes).

    Science.gov (United States)

    Matsuno, Toyomi; Tomonaga, Masaki

    2017-01-01

    Extracting a cause-and-effect structure from the physical world is an important demand for animals living in dynamically changing environments. Human perceptual and cognitive mechanisms are known to be sensitive and tuned to detect and interpret such causal structures. In contrast to rigorous investigations of human causal perception, the phylogenetic roots of this perception are not well understood. In the present study, we aimed to investigate the susceptibility of nonhuman animals to mechanical causality by testing whether chimpanzees perceived an illusion called causal capture (Scholl & Nakayama, 2002). Causal capture is a phenomenon in which a type of bistable visual motion of objects is perceived as causal collision due to a bias from a co-occurring causal event. In our experiments, we assessed the susceptibility of perception of a bistable stream/bounce motion event to a co-occurring causal event in chimpanzees. The results show that, similar to in humans, causal "bounce" percepts were significantly increased in chimpanzees with the addition of a task-irrelevant causal bounce event that was synchronously presented. These outcomes suggest that the perceptual mechanisms behind the visual interpretation of causal structures in the environment are evolutionarily shared between human and nonhuman animals. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. CADDIS Volume 1. Stressor Identification: About Causal Assessment

    Science.gov (United States)

    An introduction to the history of our approach to causal assessment, A chronology of causal history and philosophy, An introduction to causal history and philosophy, References for the Causal Assessment Background section of Stressor Identification

  4. Causal viscous cosmology without singularities

    CERN Document Server

    Laciana, Carlos E

    2016-01-01

    An isotropic and homogeneous cosmological model with a source of dark energy is studied. That source is simulated with a viscous relativistic fluid with minimal causal correction. In this model the restrictions on the parameters coming from the following conditions are analized: a) energy density without singularities along time, b) scale factor increasing with time, c) universe accelerated at present time, d) state equation for dark energy with "w" bounded and close to -1. It is found that those conditions are satified for the following two cases. i) When the transport coefficient ({\\tau}_{{\\Pi}}), associated to the causal correction, is negative, with the aditional restriction {\\zeta}|{\\tau}_{{\\Pi}}|>2/3, where {\\zeta} is the relativistic bulk viscosity coefficient. The state equation is in the "phantom" energy sector. ii) For {\\tau}_{{\\Pi}} positive, in the "k-essence" sector. It is performed an exact calculation for the case where the equation of state is constant, finding that option (ii) is favored in r...

  5. Space and time in perceptual causality

    Directory of Open Access Journals (Sweden)

    Benjamin Straube

    2010-04-01

    Full Text Available Inferring causality is a fundamental feature of human cognition that allows us to theorize about and predict future states of the world. Michotte suggested that humans automatically perceive causality based on certain perceptual features of events. However, individual differences in judgments of perceptual causality cast doubt on Michotte’s view. To gain insights in the neural basis of individual difference in the perception of causality, our participants judged causal relationships in animations of a blue ball colliding with a red ball (a launching event while fMRI-data were acquired. Spatial continuity and temporal contiguity were varied parametrically in these stimuli. We did not find consistent brain activation differences between trials judged as caused and those judged as non-caused, making it unlikely that humans have universal instantiation of perceptual causality in the brain. However, participants were slower to respond to and showed greater neural activity for violations of causality, suggesting that humans are biased to expect causal relationships when moving objects appear to interact. Our participants demonstrated considerable individual differences in their sensitivity to spatial and temporal characteristics in perceiving causality. These qualitative differences in sensitivity to time or space in perceiving causality were instantiated in individual differences in activation of the left basal ganglia or right parietal lobe, respectively. Thus, the perception that the movement of one object causes the movement of another is triggered by elemental spatial and temporal sensitivities, which themselves are instantiated in specific distinct neural networks.

  6. The Functions of Danish Causal Conjunctions

    Directory of Open Access Journals (Sweden)

    Rita Therkelsen

    2004-01-01

    Full Text Available In the article I propose an analysis of the Danish causal conjunctions fordi, siden and for based on the framework of Danish Functional Grammar. As conjunctions they relate two clauses, and their semantics have in common that it indicates a causal relationship between the clauses. The causal conjunctions are different as far as their distribution is concerned; siden conjoins a subordinate clause and a main clause, for conjoins two main clauses, and fordi is able to do both. Methodologically I have based my analysis on these distributional properties comparing siden and fordi conjoining a subordinate and a main clause, and comparing for and fordi conjoining two main clauses, following the thesis that they would establish a causal relationship between different kinds of content. My main findings are that fordi establishes a causal relationship between the events referred to by the two clauses, and the whole utterance functions as a statement of this causal relationship. Siden presupposes such a general causal relationship between the two events and puts forward the causing event as a reason for assuming or wishing or ordering the caused event, siden thus establishes a causal relationship between an event and a speech act. For equally presupposes a general causal relationship between two events and it establishes a causal relationship between speech acts, and fordi conjoining two main clauses is able to do this too, but in this position it also maintains its event-relating ability, the interpretation depending on contextual factors.

  7. Respuesta al glifosato de un aislamiento de Rhizoctonia solani agente causal del anublo de la vaina del arroz, y de cuatro aislamientos de Trichoderma, bajo condiciones in vitro In vitro response of one isolate of Rhizoctonia solani, the pathogen of the rice sheath blight and four isolates of Trichoderma to glyphosate

    Directory of Open Access Journals (Sweden)

    Vargas de Álvarez Amparo

    2002-08-01

    Full Text Available El añublo de la vaina del arroz (Orysa saliva L., cuyo agente causal es Rhizoctonia solani Kuhn, es una de las enfermedades más importantes en el cultivo del arroz en Colombia. En los cultivos de arroz con frecuencia se aplica glifosato ((ácido N-(fosfonometil glicina para controlar las malezas, particularmente el arroz rojo (O. saliva, antes de la siembra del arroz. Observaciones de campo anteriores parecían indicar relación entre el uso intensivo del glifosato y el incremento en la incidencia del añublo de la vaina del arroz. Por tanto, se propuso el presente trabajo con el fin de dilucidar los posibles efectos del glifosato sobre R. solani y Trichoderma sp., conocido éste como antagonista de R. solani. Se determinó, bajo condiciones de laboratorio, el efecto del glifosato en el crecimiento, en medio líquido y sólido PDA, de R. solani y de Trichoderma. Se encontró que la dosis más alta de glifosato sin efecto detrimental sobre R. solani, fue de 300 mg/L y la dosis más baja del herbicida que
    causó la mayor inhibición del crecimiento del hongo fue
    de 2500 mg/L. Por otra parte, no se encontró que el glifosato
    estimulara el crecimiento de R. solani. En teoría, en una aplicación comercial de glifosato de 1,5 Kg ia/ha y asperjando directamente al suelo sin vegetación, el glifosato en el suelo estaría a una concentración de 0,75 mg/Kg de suelo (suponiendo que la capa arable de una hectárea de suelo pesa 2.000.000 de Kg; por tanto, la concentración de glifosato después de una aplicación comercial, está muy por debajo de la concentración a la cual se inicia la reducción del crecimiento de R. solani. Por su parte, la respuesta de Trichoderma al glifosato fue similar a la de R. solani; además, se encontró que el glifosato no afecta la capacidad antagonista de Trichoderma sobre R. sotaní. Estos resultados no apoyan la hipótesis que el glifosato, bajo las condiciones de uso en cultivos de arroz para el control

  8. Linear causal modeling with structural equations

    CERN Document Server

    Mulaik, Stanley A

    2009-01-01

    Emphasizing causation as a functional relationship between variables that describe objects, Linear Causal Modeling with Structural Equations integrates a general philosophical theory of causation with structural equation modeling (SEM) that concerns the special case of linear causal relations. In addition to describing how the functional relation concept may be generalized to treat probabilistic causation, the book reviews historical treatments of causation and explores recent developments in experimental psychology on studies of the perception of causation. It looks at how to perceive causal

  9. Causal feedbacks in climate change

    Science.gov (United States)

    van Nes, Egbert H.; Scheffer, Marten; Brovkin, Victor; Lenton, Timothy M.; Ye, Hao; Deyle, Ethan; Sugihara, George

    2015-05-01

    The statistical association between temperature and greenhouse gases over glacial cycles is well documented, but causality behind this correlation remains difficult to extract directly from the data. A time lag of CO2 behind Antarctic temperature--originally thought to hint at a driving role for temperature--is absent at the last deglaciation, but recently confirmed at the last ice age inception and the end of the earlier termination II (ref. ). We show that such variable time lags are typical for complex nonlinear systems such as the climate, prohibiting straightforward use of correlation lags to infer causation. However, an insight from dynamical systems theory now allows us to circumvent the classical challenges of unravelling causation from multivariate time series. We build on this insight to demonstrate directly from ice-core data that, over glacial-interglacial timescales, climate dynamics are largely driven by internal Earth system mechanisms, including a marked positive feedback effect from temperature variability on greenhouse-gas concentrations.

  10. Modelagem causal da astronomia antiga

    OpenAIRE

    Rodrigo Cristino de Faria

    2014-01-01

    Esta dissertação tem como objetivo apresentar a Modelagem Causal em História da Ciência (MCHC), e aplicá-la ao período da história da astronomia que vai dos primórdios ao século III AEC. Na primeira parte, exponho o método e discorro sobre algumas de suas implicações filosóficas especialmente aquelas relacionadas com a noção de avanço e historiográficas, ao mesmo tempo em que procuro inseri-lo no panorama da filosofia da ciência. Na segunda parte, que já é uma aplicação da MCHC, apresento u...

  11. [Causality in occupational oncology: the toxicologist opinion].

    Science.gov (United States)

    Lotti, Marcello

    2011-01-01

    General and individual causality in occupational oncology should be regarded as diverse and largely autonomous concepts. General causality is based upon a statement such as "the chemical is a carcinogen" and must be considered for preventive action. Individual causality implies that the statement has to be applied to a patient exposed to that chemical. Whereas cancer results from complex interactions between genes and, in broad sense, the environment, the individual causality is an empirical judgement (educated guess) based upon all information about the substance itself and the individual patient.

  12. Heterogeneous Causal Effects and Sample Selection Bias

    DEFF Research Database (Denmark)

    Breen, Richard; Choi, Seongsoo; Holm, Anders

    2015-01-01

    causal effects might vary over individuals or groups. In this paper we point out one of the under-appreciated hazards of seeking to estimate heterogeneous causal effects: conventional selection bias (that is, selection on baseline differences) can easily be mistaken for heterogeneity of causal effects....... This might lead us to find heterogeneous effects when the true effect is homogenous, or to wrongly estimate not only the magnitude but also the sign of heterogeneous effects. We apply a test for the robustness of heterogeneous causal effects in the face of varying degrees and patterns of selection bias...

  13. Characterization of a Colletotrichum population causing anthracnose disease on Olive in northern Tunisia.

    Science.gov (United States)

    Chattaoui, M; Raya, M C; Bouri, M; Moral, J; Perez-Rodriguez, M; Trapero, A; Msallem, M; Rhouma, A

    2016-05-01

    To phenotypically, physiologically and molecularly characterize the causal agent of olive anthracnose in the northern Tunisia and to study its genetic variability and pathogenicity. A total of 43 isolates were obtained from symptomatic olives collected from four regions in northern Tunisia. A range of morphological and physiological characteristics was recorded; and a phylogenetic study, based on the sequence analysis of both internal transcribed spacers and TUB2 gene regions, was performed. Of the 43 isolates, 41 were identified as Colletotrichum acutatum s.s, and only two were affiliated to Colletotrichum gloeosporioides s.s. Two more representative Spanish isolates, included for comparison, were identified as Colletotrichum godetiae. Using six inter-simple-sequence-repeat markers, homogeneity between isolates from different locations and within the same species was recorded. In pathogenicity and virulence studies, C. gloeosporioides s.s was found to be less virulent, while the Spanish C. godetiae isolate was significantly more virulent than the Tunisian C. acutatum s.s. Olive anthracnose in the North of Tunisia is mainly caused by C. acutatum s.s species. This is the first study of olive anthracnose in Tunisia, which combines both phenotypic and molecular approaches. Colletotrichum acutatum s.s group was recorded for the first time in the country as the causal agent of olive anthracnose. © 2016 The Society for Applied Microbiology.

  14. Causal ubiquity in quantum physics. A superluminal and local-causal physical ontology

    Energy Technology Data Exchange (ETDEWEB)

    Neelamkavil, Raphael

    2014-07-01

    A fixed highest criterial velocity (of light) in STR (special theory of relativity) is a convention for a layer of physical inquiry. QM (Quantum Mechanics) avoids action-at-a-distance using this concept, but accepts non-causality and action-at-a-distance in EPR (Einstein-Podolsky-Rosen-Paradox) entanglement experiments. Even in such allegedly [non-causal] processes, something exists processually in extension-motion, between the causal and the [non-causal]. If STR theoretically allows real-valued superluminal communication between EPR entangled particles, quantum processes become fully causal. That is, the QM world is sub-luminally, luminally and superluminally local-causal throughout, and the Law of Causality is ubiquitous in the micro-world. Thus, ''probabilistic causality'' is a merely epistemic term.

  15. The gut microbiota and obesity: from correlation to causality.

    Science.gov (United States)

    Zhao, Liping

    2013-09-01

    The gut microbiota has been linked with chronic diseases such as obesity in humans. However, the demonstration of causality between constituents of the microbiota and specific diseases remains an important challenge in the field. In this Opinion article, using Koch's postulates as a conceptual framework, I explore the chain of causation from alterations in the gut microbiota, particularly of the endotoxin-producing members, to the development of obesity in both rodents and humans. I then propose a strategy for identifying the causative agents of obesity in the human microbiota through a combination of microbiome-wide association studies, mechanistic analysis of host responses and the reproduction of diseases in gnotobiotic animals.

  16. A qualitative study evaluating causality attribution for serious adverse events during early phase oncology clinical trials.

    Science.gov (United States)

    Mukherjee, Som D; Coombes, Megan E; Levine, Mitch; Cosby, Jarold; Kowaleski, Brenda; Arnold, Andrew

    2011-10-01

    In early phase oncology trials, novel targeted therapies are increasingly being tested in combination with traditional agents creating greater potential for enhanced and new toxicities. When a patient experiences a serious adverse event (SAE), investigators must determine whether the event is attributable to the investigational drug or not. This study seeks to understand the clinical reasoning, tools used and challenges faced by the researchers who assign causality to SAE's. Thirty-two semi-structured interviews were conducted with medical oncologists and trial coordinators at six Canadian academic cancer centres. Interviews were recorded and transcribed verbatim. Individual interview content analysis was followed by thematic analysis across the interview set. Our study found that causality assessment tends to be a rather complex process, often without complete clinical and investigational data at hand. Researchers described using a common processing strategy whereby they gather pertinent information, eliminate alternative explanations, and consider whether or not the study drug resulted in the SAE. Many of the interviewed participants voiced concern that causality assessments are often conducted quickly and tend to be highly subjective. Many participants were unable to identify any useful tools to help in assigning causality and welcomed more objectivity in the overall process. Attributing causality to SAE's is a complex process. Clinical trial researchers apply a logical system of reasoning, but feel that the current method of assigning causality could be improved. Based on these findings, future research involving the development of a new causality assessment tool specifically for use in early phase oncology clinical trials may be useful.

  17. Causal Systems Categories: Differences in Novice and Expert Categorization of Causal Phenomena

    Science.gov (United States)

    Rottman, Benjamin M.; Gentner, Dedre; Goldwater, Micah B.

    2012-01-01

    We investigated the understanding of causal systems categories--categories defined by common causal structure rather than by common domain content--among college students. We asked students who were either novices or experts in the physical sciences to sort descriptions of real-world phenomena that varied in their causal structure (e.g., negative…

  18. Causal random geometry from stochastic quantization

    DEFF Research Database (Denmark)

    Ambjørn, Jan; Loll, R.; Westra, W.

    2010-01-01

     in this short note we review a recently found formulation of two-dimensional causal quantum gravity defined through Causal Dynamical Triangulations and stochastic quantization. This procedure enables one to extract the nonperturbative quantum Hamiltonian of the random surface model including...... the sum over topologies. Interestingly, the generally fictitious stochastic time corresponds to proper time on the geometries...

  19. Causal random geometry from stochastic quantization

    NARCIS (Netherlands)

    Ambjørn, J.; Loll, R.|info:eu-repo/dai/nl/304830720; Westra, W.|info:eu-repo/dai/nl/304832073; Zohren, S.

    2010-01-01

    In this short note we review a recently found formulation of two-dimensional causal quantum gravity defined through Causal Dynamical Triangulations and stochastic quantization. This procedure enables one to extract the nonperturbative quantum Hamiltonian of the random surface model including the sum

  20. mediation: R Package for Causal Mediation Analysis

    Directory of Open Access Journals (Sweden)

    Dustin Tingley

    2014-09-01

    Full Text Available In this paper, we describe the R package mediation for conducting causal mediation analysis in applied empirical research. In many scientific disciplines, the goal of researchers is not only estimating causal effects of a treatment but also understanding the process in which the treatment causally affects the outcome. Causal mediation analysis is frequently used to assess potential causal mechanisms. The mediation package implements a comprehensive suite of statistical tools for conducting such an analysis. The package is organized into two distinct approaches. Using the model-based approach, researchers can estimate causal mediation effects and conduct sensitivity analysis under the standard research design. Furthermore, the design-based approach provides several analysis tools that are applicable under different experimental designs. This approach requires weaker assumptions than the model-based approach. We also implement a statistical method for dealing with multiple (causally dependent mediators, which are often encountered in practice. Finally, the package also offers a methodology for assessing causal mediation in the presence of treatment noncompliance, a common problem in randomized trials.

  1. Updating during Reading Comprehension: Why Causality Matters

    Science.gov (United States)

    Kendeou, Panayiota; Smith, Emily R.; O'Brien, Edward J.

    2013-01-01

    The present set of 7 experiments systematically examined the effectiveness of adding causal explanations to simple refutations in reducing or eliminating the impact of outdated information on subsequent comprehension. The addition of a single causal-explanation sentence to a refutation was sufficient to eliminate any measurable disruption in…

  2. Nonlinear Granger Causality: Guidelines for Multivariate Analysis

    NARCIS (Netherlands)

    Diks, C.; Wolski, M.

    2013-01-01

    In this paper we propose an extension of the nonparametric Granger causality test, originally introduced by Diks and Panchenko [2006. A new statistic and practical guidelines for nonparametric Granger causality testing. Journal of Economic Dynamics \\& Control 30, 1647-1669]. We show that the basic

  3. Essays on Causal Inference for Public Policy

    Science.gov (United States)

    Zajonc, Tristan

    2012-01-01

    Effective policymaking requires understanding the causal effects of competing proposals. Relevant causal quantities include proposals' expected effect on different groups of recipients, the impact of policies over time, the potential trade-offs between competing objectives, and, ultimately, the optimal policy. This dissertation studies causal…

  4. Determining Directional Dependency in Causal Associations

    Science.gov (United States)

    Pornprasertmanit, Sunthud; Little, Todd D.

    2012-01-01

    Directional dependency is a method to determine the likely causal direction of effect between two variables. This article aims to critique and improve upon the use of directional dependency as a technique to infer causal associations. We comment on several issues raised by von Eye and DeShon (2012), including: encouraging the use of the signs of…

  5. Quantum-coherent mixtures of causal relations

    Science.gov (United States)

    MacLean, Jean-Philippe W.; Ried, Katja; Spekkens, Robert W.; Resch, Kevin J.

    2017-01-01

    Understanding the causal influences that hold among parts of a system is critical both to explaining that system's natural behaviour and to controlling it through targeted interventions. In a quantum world, understanding causal relations is equally important, but the set of possibilities is far richer. The two basic ways in which a pair of time-ordered quantum systems may be causally related are by a cause-effect mechanism or by a common-cause acting on both. Here we show a coherent mixture of these two possibilities. We realize this nonclassical causal relation in a quantum optics experiment and derive a set of criteria for witnessing the coherence based on a quantum version of Berkson's effect, whereby two independent causes can become correlated on observation of their common effect. The interplay of causality and quantum theory lies at the heart of challenging foundational puzzles, including Bell's theorem and the search for quantum gravity. PMID:28485394

  6. Causal ubiquity in quantum physics a superluminal and local-causal physical ontology

    CERN Document Server

    Neelamkavil, Raphael

    2014-01-01

    A fixed highest criterial velocity (of light) in STR (special theory of relativity) is a convention for a layer of physical inquiry. QM (Quantum Mechanics) avoids action-at-a-distance using this concept, but accepts non-causality and action-at-a-distance in EPR (Einstein-Podolsky-Rosen-Paradox) entanglement experiments. Even in such allegedly non-causal processes, something exists processually in extension-motion, between the causal and the non-causal. If STR theoretically allows real-valued superluminal communication between EPR entangled particles, quantum processes become fully causal. That

  7. Summarizing Simulation Results using Causally-relevant States

    Science.gov (United States)

    Parikh, Nidhi; Marathe, Madhav; Swarup, Samarth

    2016-01-01

    As increasingly large-scale multiagent simulations are being implemented, new methods are becoming necessary to make sense of the results of these simulations. Even concisely summarizing the results of a given simulation run is a challenge. Here we pose this as the problem of simulation summarization: how to extract the causally-relevant descriptions of the trajectories of the agents in the simulation. We present a simple algorithm to compress agent trajectories through state space by identifying the state transitions which are relevant to determining the distribution of outcomes at the end of the simulation. We present a toy-example to illustrate the working of the algorithm, and then apply it to a complex simulation of a major disaster in an urban area. PMID:28042620

  8. The Role of Causal and Intentional Judgments in Moral Reasoning in Individuals with High Functioning Autism

    Science.gov (United States)

    Buon, Marine; Dupoux, Emmanuel; Jacob, Pierre; Chaste, Pauline; Leboyer, Marion; Zalla, Tiziana

    2013-01-01

    In the present study, we investigated the ability to assign moral responsibility and punishment in adults with high functioning autism or Asperger Syndrome (HFA/AS), using non-verbal cartoons depicting an aggression, an accidental harm or a mere coincidence. Participants were asked to evaluate the agent's causal and intentional roles, his…

  9. Quantum correlations with no causal order.

    Science.gov (United States)

    Oreshkov, Ognyan; Costa, Fabio; Brukner, Caslav

    2012-01-01

    The idea that events obey a definite causal order is deeply rooted in our understanding of the world and at the basis of the very notion of time. But where does causal order come from, and is it a necessary property of nature? Here, we address these questions from the standpoint of quantum mechanics in a new framework for multipartite correlations that does not assume a pre-defined global causal structure but only the validity of quantum mechanics locally. All known situations that respect causal order, including space-like and time-like separated experiments, are captured by this framework in a unified way. Surprisingly, we find correlations that cannot be understood in terms of definite causal order. These correlations violate a 'causal inequality' that is satisfied by all space-like and time-like correlations. We further show that in a classical limit causal order always arises, which suggests that space-time may emerge from a more fundamental structure in a quantum-to-classical transition.

  10. Causality and Time in Historical Institutionalism

    DEFF Research Database (Denmark)

    Mahoney, James; Mohamedali, Khairunnisa; Nguyen, Christoph

    2016-01-01

    This chapter explores the dual concern with causality and time in historical institutionalism using a graphical approach. The analysis focuses on three concepts that are central to this field: critical junctures, gradual change, and path dependence. The analysis makes explicit and formal the logic...... underlying studies that use these “causal-temporal” concepts. The chapter shows visually how causality and temporality are linked to one another in varying ways depending on the particular pattern of change. The chapter provides new tools for describing and understanding change in historical- institutional...

  11. Dual Causality and the Autonomy of Biology.

    Science.gov (United States)

    Bock, Walter J

    2017-03-01

    Ernst Mayr's concept of dual causality in biology with the two forms of causes (proximate and ultimate) continues to provide an essential foundation for the philosophy of biology. They are equivalent to functional (=proximate) and evolutionary (=ultimate) causes with both required for full biological explanations. The natural sciences can be classified into nomological, historical nomological and historical dual causality, the last including only biology. Because evolutionary causality is unique to biology and must be included for all complete biological explanations, biology is autonomous from the physical sciences.

  12. Causal Reasoning and Developmental Change over the Preschool Years.

    Science.gov (United States)

    Bullock, Merry

    1985-01-01

    Explores implications of two cognitive development perspectives for characterizing ontogeny of causal reasoning. Reviews literature on causal reasoning in the preschool years and concludes that the hypothesis of an invariant causal scheme is only partially correct. (Author/SO)

  13. Causality and the Semantics of Provenance

    Directory of Open Access Journals (Sweden)

    James Cheney

    2010-06-01

    Full Text Available Provenance, or information about the sources, derivation, custody or history of data, has been studied recently in a number of contexts, including databases, scientific workflows and the Semantic Web. Many provenance mechanisms have been developed, motivated by informal notions such as influence, dependence, explanation and causality. However, there has been little study of whether these mechanisms formally satisfy appropriate policies or even how to formalize relevant motivating concepts such as causality. We contend that mathematical models of these concepts are needed to justify and compare provenance techniques. In this paper we review a theory of causality based on structural models that has been developed in artificial intelligence, and describe work in progress on using causality to give a semantics to provenance graphs.

  14. Special Relativity, Causality and Quantum Mechanics-2

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 11; Issue 9. Special Relativity, Causality and Quantum Mechanics - 2. Guruprasad Kar Samir Kunkri Sujit K Choudhary. General Article Volume 11 Issue 9 September 2006 pp 43-54 ...

  15. Unveiling causal activity of complex networks

    Science.gov (United States)

    Williams-García, Rashid V.; Beggs, John M.; Ortiz, Gerardo

    2017-07-01

    We introduce a novel tool for analyzing complex network dynamics, allowing for cascades of causally-related events, which we call causal webs (c-webs), to be separated from other non-causally-related events. This tool shows that traditionally-conceived avalanches may contain mixtures of spatially-distinct but temporally-overlapping cascades of events, and dynamical disorder or noise. In contrast, c-webs separate these components, unveiling previously hidden features of the network and dynamics. We apply our method to mouse cortical data with resulting statistics which demonstrate for the first time that neuronal avalanches are not merely composed of causally-related events. The original version of this article was uploaded to the arXiv on March 17th, 2016 [1].

  16. Causality, teleology and explanation in social sciences

    OpenAIRE

    Crespo, Ricardo F

    2016-01-01

    Causality and explanation are hot topics in the contemporary philosophy of natural and social sciences. The dissatisfaction with some “classical” accounts of scientific explanation (such as the deductive-nomological or covering law model, or the inductive and deductive statistical explanation) leads philosophers of science to probe the possibilities of causal explanations. However, instead of unanimous notions on causation and explanation, a plethora of concepts emerged.2 This ...

  17. Causality violation, gravitational shockwaves and UV completion

    Energy Technology Data Exchange (ETDEWEB)

    Hollowood, Timothy J.; Shore, Graham M. [Department of Physics, Swansea University,Swansea, SA2 8PP (United Kingdom)

    2016-03-18

    The effective actions describing the low-energy dynamics of QFTs involving gravity generically exhibit causality violations. These may take the form of superluminal propagation or Shapiro time advances and allow the construction of “time machines”, i.e. spacetimes admitting closed non-spacelike curves. Here, we discuss critically whether such causality violations may be used as a criterion to identify unphysical effective actions or whether, and how, causality problems may be resolved by embedding the action in a fundamental, UV complete QFT. We study in detail the case of photon scattering in an Aichelburg-Sexl gravitational shockwave background and calculate the phase shifts in QED for all energies, demonstrating their smooth interpolation from the causality-violating effective action values at low-energy to their manifestly causal high-energy limits. At low energies, these phase shifts may be interpreted as backwards-in-time coordinate jumps as the photon encounters the shock wavefront, and we illustrate how the resulting causality problems emerge and are resolved in a two-shockwave time machine scenario. The implications of our results for ultra-high (Planck) energy scattering, in which graviton exchange is modelled by the shockwave background, are highlighted.

  18. Kant on causal laws and powers.

    Science.gov (United States)

    Henschen, Tobias

    2014-12-01

    The aim of the paper is threefold. Its first aim is to defend Eric Watkins's claim that for Kant, a cause is not an event but a causal power: a power that is borne by a substance, and that, when active, brings about its effect, i.e. a change of the states of another substance, by generating a continuous flow of intermediate states of that substance. The second aim of the paper is to argue against Watkins that the Kantian concept of causal power is not the pre-critical concept of real ground but the category of causality, and that Kant holds with Hume that causal laws cannot be inferred non-inductively (that he accordingly has no intention to show in the Second analogy or elsewhere that events fall under causal laws). The third aim of the paper is to compare the Kantian position on causality with central tenets of contemporary powers ontology: it argues that unlike the variants endorsed by contemporary powers theorists, the Kantian variants of these tenets are resistant to objections that neo-Humeans raise to these tenets.

  19. Transitive reasoning distorts induction in causal chains.

    Science.gov (United States)

    von Sydow, Momme; Hagmayer, York; Meder, Björn

    2016-04-01

    A probabilistic causal chain A→B→C may intuitively appear to be transitive: If A probabilistically causes B, and B probabilistically causes C, A probabilistically causes C. However, probabilistic causal relations can only guaranteed to be transitive if the so-called Markov condition holds. In two experiments, we examined how people make probabilistic judgments about indirect relationships A→C in causal chains A→B→C that violate the Markov condition. We hypothesized that participants would make transitive inferences in accordance with the Markov condition although they were presented with counterevidence showing intransitive data. For instance, participants were successively presented with data entailing positive dependencies A→B and B→C. At the same time, the data entailed that A and C were statistically independent. The results of two experiments show that transitive reasoning via a mediating event B influenced and distorted the induction of the indirect relation between A and C. Participants' judgments were affected by an interaction of transitive, causal-model-based inferences and the observed data. Our findings support the idea that people tend to chain individual causal relations into mental causal chains that obey the Markov condition and thus allow for transitive reasoning, even if the observed data entail that such inferences are not warranted.

  20. Manipulating Morality: Third-Party Intentions Alter Moral Judgments by Changing Causal Reasoning.

    Science.gov (United States)

    Phillips, Jonathan; Shaw, Alex

    2015-08-01

    The present studies investigate how the intentions of third parties influence judgments of moral responsibility for other agents who commit immoral acts. Using cases in which an agent acts under some situational constraint brought about by a third party, we ask whether the agent is blamed less for the immoral act when the third party intended for that act to occur. Study 1 demonstrates that third-party intentions do influence judgments of blame. Study 2 finds that third-party intentions only influence moral judgments when the agent's actions precisely match the third party's intention. Study 3 shows that this effect arises from changes in participants' causal perception that the third party was controlling the agent. Studies 4 and 5, respectively, show that the effect cannot be explained by changes in the distribution of blame or perceived differences in situational constraint faced by the agent. © 2014 Cognitive Science Society, Inc.

  1. The Relevance of Causal Social Construction

    Directory of Open Access Journals (Sweden)

    Marques Teresa

    2017-02-01

    Full Text Available Social constructionist claims are surprising and interesting when they entail that presumably natural kinds are in fact socially constructed. The claims are interesting because of their theoretical and political importance. Authors like Díaz-León argue that constitutive social construction is more relevant for achieving social justice than causal social construction. This paper challenges this claim. Assuming there are socially salient groups that are discriminated against, the paper presents a dilemma: if there were no constitutively constructed social kinds, the causes of the discrimination of existing social groups would have to be addressed, and understanding causal social construction would be relevant to achieve social justice. On the other hand, not all possible constitutively socially constructed kinds are actual social kinds. If an existing social group is constitutively constructed as a social kind K, the fact that it actually exists as a K has social causes. Again, causal social construction is relevant. The paper argues that (i for any actual social kind X, if X is constitutively socially constructed as K, then it is also causally socially constructed; and (ii causal social construction is at least as relevant as constitutive social construction for concerns of social justice. For illustration, I draw upon two phenomena that are presumed to contribute towards the discrimination of women: (i the poor performance effects of stereotype threat, and (ii the silencing effects of gendered language use.

  2. Inferring Non-Observed Correlations from Causal Scenarios: The Role of Causal Knowledge

    Science.gov (United States)

    Perales, Jose C.; Catena, Andres; Maldonado, Antonio

    2004-01-01

    This work aimed at demonstrating, first, that naive reasoners are able to infer the existence of a relationship between two events that have never been presented together and, second, the sensitivity of such inference to the causal structure of the task. In all experiments, naive participants judged the strength of the causal link between a cue A…

  3. Causality in 3D massive gravity theories

    Science.gov (United States)

    Edelstein, José D.; Giribet, Gaston; Gómez, Carolina; Kilicarslan, Ercan; Leoni, Matías; Tekin, Bayram

    2017-05-01

    We study the constraints coming from the local causality requirement in various 2 +1 dimensional dynamical theories of gravity. In topologically massive gravity, with a single parity noninvariant massive degree of freedom, and in new massive gravity, with two massive spin-2 degrees of freedom, causality and unitarity are compatible with each other and both require the Newton's constant to be negative. In their extensions, such as the Born-Infeld gravity and the minimal massive gravity the situation is similar and quite different from their higher dimensional counterparts, such as quadratic (e.g., Einstein-Gauss-Bonnet) or cubic theories, where causality and unitarity are in conflict. We study the problem both in asymptotically flat and asymptotically anti-de Sitter spaces.

  4. Diabetes: the layperson's theories of causality.

    Science.gov (United States)

    Mercado-Martinez, Francisco J; Ramos-Herrera, Igor Martin

    2002-07-01

    The authors examine laypersons' perspectives of illness: the content of causal explanations of diabetes and differences in explanations according to gender. Qualitative research was carried out in Guadalajara, Mexico. A nonprobabilistic sample of 20 diabetic individuals participated in interviews, and the content of the interviews was analyzed. On the origin of their condition, participants offered explanations that match neither the biomedical model nor any other formal causal theory. Participants attributed the onset of diabetes to socioemotional circumstances linked to their life experiences and practices. Men attributed causality to work and social circumstances outside the home; women attributed it to family life and domestic circumstances. The authors discuss how lay theories can be useful for the reorganization of health services.

  5. Causal diagrams, information bias, and thought bias.

    Science.gov (United States)

    Shahar, Eyal; Shahar, Doron J

    2010-01-01

    Information bias might be present in any study, including randomized trials, because the values of variables of interest are unknown, and researchers have to rely on substitute variables, the values of which provide information on the unknown true values. We used causal directed acyclic graphs to extend previous work on information bias. First, we show that measurement is a complex causal process that has two components, ie, imprinting and synthesizing. Second, we explain how the unknown values of a variable may be imputed from other variables, and present examples of valid and invalid substitutions for a variable of interest. Finally, and most importantly, we describe a previously unrecognized bias, which may be viewed as antithetical to information bias. This bias arises whenever a variable does not exist in the physical world, yet researchers obtain "information" on its nonexistent values and estimate nonexistent causal parameters. According to our thesis, the scientific literature contains many articles that are affected by such bias.

  6. Causal inheritence in plane wave quotients

    Energy Technology Data Exchange (ETDEWEB)

    Hubeny, Veronika E.; Rangamani, Mukund; Ross, Simon F.

    2003-11-24

    We investigate the appearance of closed timelike curves in quotients of plane waves along spacelike isometries. First we formulate a necessary and sufficient condition for a quotient of a general spacetime to preserve stable causality. We explicitly show that the plane waves are stably causal; in passing, we observe that some pp-waves are not even distinguishing. We then consider the classification of all quotients of the maximally supersymmetric ten-dimensional plane wave under a spacelike isometry, and show that the quotient will lead to closed timelike curves iff the isometry involves a translation along the u direction. The appearance of these closed timelike curves is thus connected to the special properties of the light cones in plane wave spacetimes. We show that all other quotients preserve stable causality.

  7. Structural intervention distance for evaluating causal graphs.

    Science.gov (United States)

    Peters, Jonas; Bühlmann, Peter

    2015-03-01

    Causal inference relies on the structure of a graph, often a directed acyclic graph (DAG). Different graphs may result in different causal inference statements and different intervention distributions. To quantify such differences, we propose a (pre-)metric between DAGs, the structural intervention distance (SID). The SID is based on a graphical criterion only and quantifies the closeness between two DAGs in terms of their corresponding causal inference statements. It is therefore well suited for evaluating graphs that are used for computing interventions. Instead of DAGs, it is also possible to compare CPDAGs, completed partially DAGs that represent Markov equivalence classes. The SID differs significantly from the widely used structural Hamming distance and therefore constitutes a valuable additional measure. We discuss properties of this distance and provide a (reasonably) efficient implementation with software code available on the first author's home page.

  8. Causal interpretation of stochastic differential equations

    DEFF Research Database (Denmark)

    Sokol, Alexander; Hansen, Niels Richard

    2014-01-01

    We give a causal interpretation of stochastic differential equations (SDEs) by defining the postintervention SDE resulting from an intervention in an SDE. We show that under Lipschitz conditions, the solution to the postintervention SDE is equal to a uniform limit in probability of postintervention...... structural equation models based on the Euler scheme of the original SDE, thus relating our definition to mainstream causal concepts. We prove that when the driving noise in the SDE is a Lévy process, the postintervention distribution is identifiable from the generator of the SDE....

  9. Causality between Literacy and Labor Productivity.

    Science.gov (United States)

    Khan, Shahrukh R.; And Others

    1991-01-01

    Utilizes the Granger causality test to estimate case and effect relationships between literacy and labor productivity in Pakistani manufacturing and agricultural sectors. Despite data set limitations, literacy appears to "cause" labor productivity to increase in the manufacturing sector. (27 references) (MLH)

  10. Causal Meta-Analysis : Methodology and Applications

    NARCIS (Netherlands)

    Bax, L.J.|info:eu-repo/dai/nl/304818577

    2009-01-01

    Meta-analysis is a statistical method to summarize research data from multiple studies in a quantitative manner. This dissertation addresses a number of methodological topics in causal meta-analysis and reports the development and validation of meta-analysis software. In the first (methodological)

  11. The Causal Priority of Form in Aristotle

    Directory of Open Access Journals (Sweden)

    Kathrin Koslicki

    2014-12-01

    Full Text Available In various texts (e.g., Met. Z.17, Aristotle assigns priority to form, in its role as a principle and cause, over matter and the matter-form compound. Given the central role played by this claim in Aristotle's search for primary substance in the Metaphysics, it is important to understand what motivates him in locating the primary causal responsibility for a thing's being what it is with the form, rather than the matter. According to Met. Theta.8, actuality [energeia/entelecheia] in general is prior to potentiality [dunamis] in three ways, viz., in definition, time and substance. I propose an explicitly causal reading of this general priority claim, as it pertains to the matter-form relationship. The priority of form over matter in definition, time and substance, in my view, is best explained by appeal to the role of form as the formal, efficient and final cause of the matter-form compound, respectively, while the posteriority of matter to form according to all three notions of priority is most plausibly accounted for by the fact that the causal contribution of matter is limited to its role as material cause. When approached from this angle, the work of Met. Theta.8 can be seen to lend direct support to the more specific and explicitly causal priority claim we encounter in Met. Z.17, viz., that form is prior to matter in its role as the principle and primary cause of a matter-form compound's being what it is.

  12. Instrumental variable methods for causal inference.

    Science.gov (United States)

    Baiocchi, Michael; Cheng, Jing; Small, Dylan S

    2014-06-15

    A goal of many health studies is to determine the causal effect of a treatment or intervention on health outcomes. Often, it is not ethically or practically possible to conduct a perfectly randomized experiment, and instead, an observational study must be used. A major challenge to the validity of observational studies is the possibility of unmeasured confounding (i.e., unmeasured ways in which the treatment and control groups differ before treatment administration, which also affect the outcome). Instrumental variables analysis is a method for controlling for unmeasured confounding. This type of analysis requires the measurement of a valid instrumental variable, which is a variable that (i) is independent of the unmeasured confounding; (ii) affects the treatment; and (iii) affects the outcome only indirectly through its effect on the treatment. This tutorial discusses the types of causal effects that can be estimated by instrumental variables analysis; the assumptions needed for instrumental variables analysis to provide valid estimates of causal effects and sensitivity analysis for those assumptions; methods of estimation of causal effects using instrumental variables; and sources of instrumental variables in health studies. Copyright © 2014 John Wiley & Sons, Ltd.

  13. Special Relativity, Causality and Quantum Mechanics - 2

    Indian Academy of Sciences (India)

    We discuss the aspects of non-locality and non- separability of states of composite quantum sys- tems. The probabilistic nature of quantum mech- anical predictions, and the impossibility of clon- ing, are shown to safeguard causality in the quan- tum world. An example of a game which can be won exploiting quantum ...

  14. Assessment of resampling methods for causality testing

    NARCIS (Netherlands)

    Papana, A.; Kyrtsou, C.; Kugiumtzis, D.; Diks, C.

    2014-01-01

    Different resampling methods for the null hypothesis of non-causality are assessed. As test statistic the partial transfer entropy (PTE), an information and model-free measure, is used. Two resampling techniques,1) the time shifted surrogates and 2) the stationary bootstrap, are combined with the

  15. Inferring causality from noisy time series data

    DEFF Research Database (Denmark)

    Mønster, Dan; Fusaroli, Riccardo; Tylén, Kristian

    2016-01-01

    and even causality direction in synchronized time-series and in the presence of intermediate coupling. We find that the presence of noise deterministically reduces the level of cross-mapping fidelity, while the convergence rate exhibits higher levels of robustness. Finally, we propose that controlled noise...

  16. The metagenomic approach and causality in virology

    Directory of Open Access Journals (Sweden)

    Silvana Beres Castrignano

    2015-01-01

    Full Text Available Nowadays, the metagenomic approach has been a very important tool in the discovery of new viruses in environmental and biological samples. Here we discuss how these discoveries may help to elucidate the etiology of diseases and the criteria necessary to establish a causal association between a virus and a disease.

  17. Causality relationship between energy demand and economic ...

    African Journals Online (AJOL)

    The Johansen co integration technique reveals that one co integrating relationship exists between real GDP and Electricity demand in Nigeria. The result of the study reveals that there is unidirectional causality between energy consumption and economic growth i.e. energy consumption Granger causes economic growth in ...

  18. Causal and Teleological Explanations in Biology

    Science.gov (United States)

    Yip, Cheng-Wai

    2009-01-01

    A causal explanation in biology focuses on the mechanism by which a biological process is brought about, whereas a teleological explanation considers the end result, in the context of the survival of the organism, as a reason for certain biological processes or structures. There is a tendency among students to offer a teleological explanation…

  19. Causality and Teleology in High School Biology.

    Science.gov (United States)

    Tamir, Pinchas

    1985-01-01

    Ability to distinguish between causal (cause-effect) and teleological (means-ends) explanations was measured in 1905 twelfth-grade biology students and found to be dependent on student knowledge. Although the inability to make these distinctions contributes to misconceptions in biology, appropriate instruction can easily remedy the problem. Sample…

  20. A stochastic causality-based process algebra

    NARCIS (Netherlands)

    Brinksma, Hendrik; Katoen, Joost P.; Langerak, Romanus; Latella, Diego

    1995-01-01

    This paper discusses stochastic extensions of a simple process algebra in a causality-based setting. Atomic actions are supposed to happen after a delay that is determined by a stochastic variable with a certain distribution. A simple stochastic type of event structures is discussed, restricting the

  1. THE CAUSAL TEXTURE OF TRADE UNION ENVIRONMENTS

    African Journals Online (AJOL)

    Admin

    This paper is an attempt to fill an important gap in the existing literature on trade unions by providing a more adequate theoretical formulation of trade union environments. The discussion suggests that unlike the environment of business and related organisations whose causal texture is understood in terms of uncertainty, ...

  2. The semiclassical limit of causal dynamical triangulations

    NARCIS (Netherlands)

    Ambjørn, J.; Görlich, A.T.; Jurkiewicz, J.; Loll, R.|info:eu-repo/dai/nl/304830720; Gizbert-Studnicki, J.; Trześniewski, T.

    2011-01-01

    Previous work has shown that the macroscopic structure of the theory of quantum gravity defined by causal dynamical triangulations (CDT) is compatible with that of a de Sitter universe. After emphasizing the strictly nonperturbative nature of this semiclassical limit we present a detailed study of

  3. Quantum computation with indefinite causal structures

    Science.gov (United States)

    Araújo, Mateus; Guérin, Philippe Allard; Baumeler, ńmin

    2017-11-01

    One way to study the physical plausibility of closed timelike curves (CTCs) is to examine their computational power. This has been done for Deutschian CTCs (D-CTCs) and postselection CTCs (P-CTCs), with the result that they allow for the efficient solution of problems in PSPACE and PP, respectively. Since these are extremely powerful complexity classes, which are not expected to be solvable in reality, this can be taken as evidence that these models for CTCs are pathological. This problem is closely related to the nonlinearity of this models, which also allows, for example, cloning quantum states, in the case of D-CTCs, or distinguishing nonorthogonal quantum states, in the case of P-CTCs. In contrast, the process matrix formalism allows one to model indefinite causal structures in a linear way, getting rid of these effects and raising the possibility that its computational power is rather tame. In this paper, we show that process matrices correspond to a linear particular case of P-CTCs, and therefore that its computational power is upperbounded by that of PP. We show, furthermore, a family of processes that can violate causal inequalities but nevertheless can be simulated by a causally ordered quantum circuit with only a constant overhead, showing that indefinite causality is not necessarily hard to simulate.

  4. Black Hole Complementarity and Violation of Causality

    OpenAIRE

    Rozenblit, Moshe

    2017-01-01

    Analysis of a massive shell collapsing on a solid sphere shows that black hole complementarity (BHC) violates causality in its effort to save information conservation. In particular, this note describes a hypothetical contraption based on BHC that would allow the transfer of information from the future to the present.

  5. Are bruxism and the bite causally related?

    NARCIS (Netherlands)

    Lobbezoo, F.; Ahlberg, J.; Manfredini, D.; Winocur, E.

    2012-01-01

    In the dental profession, the belief that bruxism and dental (mal-)occlusion (‘the bite’) are causally related is widespread. The aim of this review was to critically assess the available literature on this topic. A PubMed search of the English-language literature, using the query ‘Bruxism [Majr

  6. Nonlinear Granger Causality: Guidelines for Multivariate Analysis

    NARCIS (Netherlands)

    Diks, C.; Wolski, M.

    2016-01-01

    We propose an extension of the bivariate nonparametric Diks–Panchenko Granger non-causality test to multivariate settings. We first show that the asymptotic theory for the bivariate test fails to apply to the multivariate case, because the kernel density estimator bias and variance cannot both tend

  7. THE CAUSAL TEXTURE OF TRADE UNION ENVIRONMENTS

    African Journals Online (AJOL)

    Admin

    providing a more adequate theoretical formulation of trade union environments. The discussion suggests that unlike the environment of business and related organisations whose causal texture is understood in terms of uncertainty, complexity, instability and turbulence that of trade unions needs to be understood in terms of ...

  8. Linear Response Laws and Causality in Electrodynamics

    Science.gov (United States)

    Yuffa, Alex J.; Scales, John A.

    2012-01-01

    Linear response laws and causality (the effect cannot precede the cause) are of fundamental importance in physics. In the context of classical electrodynamics, students often have a difficult time grasping these concepts because the physics is obscured by the intermingling of the time and frequency domains. In this paper, we analyse the linear…

  9. Causal Relationship between Teachers' Job Performance and ...

    African Journals Online (AJOL)

    The study investigated teachers' job performance and students' academic achievement in secondary schools for the existence of bi-causal relationship in Nigeria. The ex-post facto ... With a Cronbach alpha reliability of (α) 0.79, data was analysed using the step-wise multiple linear regression analysis. Findings showed that ...

  10. Escaping Myopia: Teaching Students about Historical Causality

    Science.gov (United States)

    Waring, Scott M.

    2010-01-01

    There are so many aspects to teaching history that are vital to creating well-rounded historical thinkers, but one of the most fundamental and most overlooked elements is the idea of causality. Far too many students do not understand the idea of causation, that there are multiple reasons for why historical events occurred and transpired in the way…

  11. Distinguishing Valid from Invalid Causal Indicator Models

    Science.gov (United States)

    Cadogan, John W.; Lee, Nick

    2016-01-01

    In this commentary from Issue 14, n3, authors John Cadogan and Nick Lee applaud the paper by Aguirre-Urreta, Rönkkö, and Marakas "Measurement: Interdisciplinary Research and Perspectives", 14(3), 75-97 (2016), since their explanations and simulations work toward demystifying causal indicator models, which are often used by scholars…

  12. Probable autoimmune causal relationship between periodontitis and ...

    African Journals Online (AJOL)

    Periodontitis is a multifactorial disease with microbial dental plaque as the initiator of periodontal disease. However, the manifestation and progression of the disease is influenced by a wide variety of determinants and factors. The strongest type of causal relationship is the association of systemic and periodontal disease.

  13. Encoding dependence in Bayesian causal networks

    Science.gov (United States)

    Bayesian networks (BNs) represent complex, uncertain spatio-temporal dynamics by propagation of conditional probabilities between identifiable states with a testable causal interaction model. Typically, they assume random variables are discrete in time and space with a static network structure that ...

  14. The Causal Relationship between Financial Development and ...

    African Journals Online (AJOL)

    The study employs cointegration, vector error correction model and Granger causality test to ascertain causation between financial development and economic performance in Tanzania. Economic performance is measured by the real GDP, whereas proxies for financial development are: the ratio of money supply to nominal ...

  15. Quantum Common Causes and Quantum Causal Models

    Science.gov (United States)

    Allen, John-Mark A.; Barrett, Jonathan; Horsman, Dominic C.; Lee, Ciarán M.; Spekkens, Robert W.

    2017-07-01

    Reichenbach's principle asserts that if two observed variables are found to be correlated, then there should be a causal explanation of these correlations. Furthermore, if the explanation is in terms of a common cause, then the conditional probability distribution over the variables given the complete common cause should factorize. The principle is generalized by the formalism of causal models, in which the causal relationships among variables constrain the form of their joint probability distribution. In the quantum case, however, the observed correlations in Bell experiments cannot be explained in the manner Reichenbach's principle would seem to demand. Motivated by this, we introduce a quantum counterpart to the principle. We demonstrate that under the assumption that quantum dynamics is fundamentally unitary, if a quantum channel with input A and outputs B and C is compatible with A being a complete common cause of B and C , then it must factorize in a particular way. Finally, we show how to generalize our quantum version of Reichenbach's principle to a formalism for quantum causal models and provide examples of how the formalism works.

  16. Reassessing the causal structure of enduring involvement

    Science.gov (United States)

    Jinhee Jun; Gerard T. Kyle; James D. Absher; William E. Hammitt

    2009-01-01

    Guided by tenets of identity theory, we hypothesized a causal structure of enduring involvement suggesting that self-relevant components precede the other dimensions. We used Kyle et al.'s (2004a) Modified Involvement Scale, in which leisure involvement is conceptualized as a multidimensional construct consisting of identity affirmation, identity expression,...

  17. Dialogue and causality: global description from local observations and vague communications.

    Science.gov (United States)

    Sawa, Koji; Gunji, Yukio-Pegio

    2007-01-01

    We propose a dialogue-based society model which explains how the transitive law of the causality is originated. Causality is, in general, formalized by using axiomatic approaches. Instead of using axiomatic methods, we, however, compose a model consisting of agents who have knowledge about causal relations among objects. The model society can reveal the transitive law through interactional dialogues among themselves. The agents are reciprocally influenced, if they have either completely same opinions, or a particular pattern of opinions, that are regarded as the extension of such exact accordance. In addition, we add some vagueness to the dialogue, which is closer to a real communication than the former model. A set of knowledge of each agent is expressed as a directed graph, hence the every model can be construed as mere transformations of directed graphs through the interactions among directed graphs themselves. Following this perspective, the models are the systems that connect local logic with global one, while the union of the directed graphs is regarded as the global.

  18. Causal knowledge and the development of inductive reasoning.

    Science.gov (United States)

    Bright, Aimée K; Feeney, Aidan

    2014-06-01

    We explored the development of sensitivity to causal relations in children's inductive reasoning. Children (5-, 8-, and 12-year-olds) and adults were given trials in which they decided whether a property known to be possessed by members of one category was also possessed by members of (a) a taxonomically related category or (b) a causally related category. The direction of the causal link was either predictive (prey→predator) or diagnostic (predator→prey), and the property that participants reasoned about established either a taxonomic or causal context. There was a causal asymmetry effect across all age groups, with more causal choices when the causal link was predictive than when it was diagnostic. Furthermore, context-sensitive causal reasoning showed a curvilinear development, with causal choices being most frequent for 8-year-olds regardless of context. Causal inductions decreased thereafter because 12-year-olds and adults made more taxonomic choices when reasoning in the taxonomic context. These findings suggest that simple causal relations may often be the default knowledge structure in young children's inductive reasoning, that sensitivity to causal direction is present early on, and that children over-generalize their causal knowledge when reasoning. Copyright © 2013 Elsevier Inc. All rights reserved.

  19. Causal Factors for The Adoption Innovation Teacher’s Tv for Teachersand Educational Personnel

    Directory of Open Access Journals (Sweden)

    Thanadol Phuseerit

    2016-12-01

    aire for the experts to examine the causal factors for the adoption innovation teacher’s TV for teachers and education personnel model by focus groups, 4 questionnaire to confirm the causal factors to an innovation teacher’s TV model for teachers and educational personnel Committee of the teacher’s TV, 5 the causal factor for the adoption innovation teacher’s TV for teachers and education personnel model, 6 evaluation form of the causal factor for the adoption of the innovation teacher’s TV for teachers and education personnel model from the specialists. The research results were: 1 The causal factors for the adoption innovation teacher’s TV for Teachers and educational personnel Model. Elements and factors are as follows: 1.1 Elements of the causes and factors of innovation teacher’s TV. Teachers and educational personnel The Review of literature and semi-structured questionnaire, interviewing Collecting quality data from in-depth interviews with a total 9 causal as fallow: (1 Characteristics of innovation, included: relative Advantage, Compatibility, Complexity, Trial ability, Observable (2 Communication Channels, included: interpersonal communication, the media as press, radio, television, communication specialized media (3 Innovation-Decision Process, included: Knowledge, Persuasion, Decision, Implementation, Confirmation (4 Economy and Social System, include: compensation and benefits. Social interaction, (5 Attitude, included: understanding the emotions, behavior (6 Motivation, included: Intrinsic motivation. External motivation (7 Support of Administrator, include: support for innovation, the budget support and materials, Academic support (8 Change agent, included: knowledge and ability, Skill-oriented capabilities Ability attitude (9 Opinion Leaders, included: access to others easily, Creative and 1element of the Adoption of the Innovation: TTV, included: the perceived ease of use, and Perceived benefits. The model’s validity of the consistency

  20. Fate of Clavibacter michiganensis ssp. sepedonicus, the causal organism of bacterial ring rot in potato, in weeds and field crops.

    NARCIS (Netherlands)

    Wolf, van der J.M.; Beckhoven, van J.R.C.M.; Hukkanen, A.; Karjalainen, R.; Muller, P.

    2005-01-01

    Crops and weeds were tested for their ability to host Clavibacter michiganensis ssp. sepedonicus (Cms), the causal agent of bacterial ring rot in potato. Ten crops grown in rotation with potato in Europe, namely maize, wheat, barley, oat, bush bean, broad bean, rape, pea and onion and five cultivars

  1. Localizing epileptic seizure onsets with Granger causality

    Science.gov (United States)

    Adhikari, Bhim M.; Epstein, Charles M.; Dhamala, Mukesh

    2013-09-01

    Accurate localization of the epileptic seizure onset zones (SOZs) is crucial for successful surgery, which usually depends on the information obtained from intracranial electroencephalography (IEEG) recordings. The visual criteria and univariate methods of analyzing IEEG recordings have not always produced clarity on the SOZs for resection and ultimate seizure freedom for patients. Here, to contribute to improving the localization of the SOZs and to understanding the mechanism of seizure propagation over the brain, we applied spectral interdependency methods to IEEG time series recorded from patients during seizures. We found that the high-frequency (>80 Hz) Granger causality (GC) occurs before the onset of any visible ictal activity and causal relationships involve the recording electrodes where clinically identifiable seizures later develop. These results suggest that high-frequency oscillatory network activities precede and underlie epileptic seizures, and that GC spectral measures derived from IEEG can assist in precise delineation of seizure onset times and SOZs.

  2. Normalizing the causality between time series

    CERN Document Server

    Liang, X San

    2015-01-01

    Recently, a rigorous yet concise formula has been derived to evaluate the information flow, and hence the causality in a quantitative sense, between time series. To assess the importance of a resulting causality, it needs to be normalized. The normalization is achieved through distinguishing three types of fundamental mechanisms that govern the marginal entropy change of the flow recipient. A normalized or relative flow measures its importance relative to other mechanisms. In analyzing realistic series, both absolute and relative information flows need to be taken into account, since the normalizers for a pair of reverse flows belong to two different entropy balances; it is quite normal that two identical flows may differ a lot in relative importance in their respective balances. We have reproduced these results with several autoregressive models. We have also shown applications to a climate change problem and a financial analysis problem. For the former, reconfirmed is the role of the Indian Ocean Dipole as ...

  3. The Hankel transform of causal distributions

    Directory of Open Access Journals (Sweden)

    Manuel A. Aguirre T.

    2012-03-01

    Full Text Available In this note we evaluate the unidimensional distributional Hankel transform of \\dfrac{x^{\\alpha-1}_{+}}{\\Gamma^{\\alpha}},\\dfrac{x^{\\alpha-1}_{-}}{\\Gamma^{\\alpha}},dfrac{|x|^{\\alpha-1}}{\\Gamma^{\\frac{\\alpha}{2}}},dfrac{|x|^{\\alpha-1}sgn(x}{\\Gamma^{\\frac{\\alpha +1}{2}}} and (x± i0^{\\alpha-1} and then we extend the formulae to certain kinds of n-dimensional distributions calles "causal" and "anti-causal" distributions. We evaluate the distributional Handel transform of \\dfrac{(m^2+P^{\\alpha -1}_{-}}{\\Gamma^{(\\alpha} }, \\dfrac{|m^2+P|^{\\alpha -1}_{-}}{\\Gamma^{(\\frac{\\alpha}{2}}}, \\dfrac{|m^2+P|^{\\alpha -1}sgn(m^2+P}{\\Gamma (\\frac{\\alpha +1}{2 }} and (m^2+P±i0^{\\alpha-1}

  4. Finite quantum electrodynamics the causal approach

    CERN Document Server

    Scharf, Günter

    2014-01-01

    In this classic text for advanced undergraduates and graduate students of physics, author Günter Scharf carefully analyzes the role of causality in quantum electrodynamics. His approach offers full proofs and detailed calculations of scattering processes in a mathematically rigorous manner. This third edition contains Scharf's revisions and corrections plus a brief new Epilogue on gauge invariance of quantum electrodynamics to all orders. The book begins with Dirac's theory, followed by the quantum theory of free fields and causal perturbation theory, a powerful method that avoids ultraviolet divergences and solves the infrared problem by means of the adiabatic limit. Successive chapters explore properties of the S-matrix — such as renormalizability, gauge invariance, and unitarity — the renormalization group, and interactive fields. Additional topics include electromagnetic couplings and the extension of the methods to non-abelian gauge theories. Each chapter is supplemented with problems, and four appe...

  5. On the Causal Mechanisms of Stuttering

    OpenAIRE

    Alm, Per A

    2005-01-01

    Stuttering is one of the most common speech disorders. However, the etiology is poorly understood, and is likely to be heterogeneous. The aim of this thesis was to clarify causal mechanisms, focusing the brain. The project included theoretical development based on published data, and a broad approach of explorative studies and testing of hypotheses. The theoretical work focused the basal ganglia, leading to a model based on the dual premotor systems hypothesis (G. Goldberg, 1985, 1991)...

  6. Equity Theory Ratios as Causal Schemas

    OpenAIRE

    Alexios Arvanitis; Alexandra Hantzi

    2016-01-01

    Equity theory approaches justice evaluations based on ratios of exchange inputs to exchange outcomes. Situations are evaluated as just if ratios are equal and unjust if unequal. We suggest that equity ratios serve a more fundamental cognitive function than the evaluation of justice. More particularly, we propose that they serve as causal schemas for exchange outcomes, that is, they assist in determining whether certain outcomes are caused by inputs of other people in the context of an exchang...

  7. Causal inference of asynchronous audiovisual speech

    Directory of Open Access Journals (Sweden)

    John F Magnotti

    2013-11-01

    Full Text Available During speech perception, humans integrate auditory information from the voice with visual information from the face. This multisensory integration increases perceptual precision, but only if the two cues come from the same talker; this requirement has been largely ignored by current models of speech perception. We describe a generative model of multisensory speech perception that includes this critical step of determining the likelihood that the voice and face information have a common cause. A key feature of the model is that it is based on a principled analysis of how an observer should solve this causal inference problem using the asynchrony between two cues and the reliability of the cues. This allows the model to make predictions abut the behavior of subjects performing a synchrony judgment task, predictive power that does not exist in other approaches, such as post hoc fitting of Gaussian curves to behavioral data. We tested the model predictions against the performance of 37 subjects performing a synchrony judgment task viewing audiovisual speech under a variety of manipulations, including varying asynchronies, intelligibility, and visual cue reliability. The causal inference model outperformed the Gaussian model across two experiments, providing a better fit to the behavioral data with fewer parameters. Because the causal inference model is derived from a principled understanding of the task, model parameters are directly interpretable in terms of stimulus and subject properties.

  8. Reducing the bias of causality measures

    Science.gov (United States)

    Papana, A.; Kugiumtzis, D.; Larsson, P. G.

    2011-03-01

    Measures of the direction and strength of the interdependence between two time series are evaluated and modified to reduce the bias in the estimation of the measures, so that they give zero values when there is no causal effect. For this, point shuffling is employed as used in the frame of surrogate data. This correction is not specific to a particular measure and it is implemented here on measures based on state space reconstruction and information measures. The performance of the causality measures and their modifications is evaluated on simulated uncoupled and coupled dynamical systems and for different settings of embedding dimension, time series length, and noise level. The corrected measures, and particularly the suggested corrected transfer entropy, turn out to stabilize at the zero level in the absence of a causal effect and detect correctly the direction of information flow when it is present. The measures are also evaluated on electroencephalograms (EEG) for the detection of the information flow in the brain of an epileptic patient. The performance of the measures on EEG is interpreted in view of the results from the simulation study.

  9. Causal tapestries for psychology and physics.

    Science.gov (United States)

    Sulis, William H

    2012-04-01

    Archetypal dynamics is a formal approach to the modeling of information flow in complex systems used to study emergence. It is grounded in the Fundamental Triad of realisation (system), interpretation (archetype) and representation (formal model). Tapestries play a fundamental role in the framework of archetypal dynamics as a formal representational system. They represent information flow by means of multi layered, recursive, interlinked graphical structures that express both geometry (form or sign) and logic (semantics). This paper presents a detailed mathematical description of a specific tapestry model, the causal tapestry, selected for use in describing behaving systems such as appear in psychology and physics from the standpoint of Process Theory. Causal tapestries express an explicit Lorentz invariant transient now generated by means of a reality game. Observables are represented by tapestry informons while subjective or hidden components (for example intellectual and emotional processes) are incorporated into the reality game that determines the tapestry dynamics. As a specific example, we formulate a random graphical dynamical system using causal tapestries.

  10. [Causality in cardiology: concepts in evolution].

    Science.gov (United States)

    Méndez, Gustavo F

    2005-01-01

    This paper describes several concepts about causality from Empedocles, Aristoteles and Galeno, to Koch and Hill and the evolution of these concepts related to cardiovascular diseases. Also defines cause and risk, and the philosophical theories about scientific knowledge: inductive versus refutation analysis. On these basis, the study of cardiovascular disease's causality, especially coronary heart disease, allows us the identification of several risk factors involved in its development. However, even with the presently coronary heart disease risk charts (from Framingham and European studies) the higher probability for the development of a cardiovascular ischemic event is around 40%, establishing an important degree of uncertainty. With the improvement in molecular biology techniques, genetics have attempted to analyse several genetic polymorphisms in search of the origin of coronary heart disease. Unfortunately, less than 10% of these polymorphisms have had a positive correlation with coronary heart disease being of minor risk that those obtained for having the diagnosis of type 2 diabetes mellitus or hypercholesterolemia. On these basis, the requirement of new population research projects in which clinical and genetic risk factors are to be studied for the appropriate understanding of the causality process of cardiovascular diseases must be a worldwide priority.

  11. Bayesian Discovery of Linear Acyclic Causal Models

    CERN Document Server

    Hoyer, Patrik O

    2012-01-01

    Methods for automated discovery of causal relationships from non-interventional data have received much attention recently. A widely used and well understood model family is given by linear acyclic causal models (recursive structural equation models). For Gaussian data both constraint-based methods (Spirtes et al., 1993; Pearl, 2000) (which output a single equivalence class) and Bayesian score-based methods (Geiger and Heckerman, 1994) (which assign relative scores to the equivalence classes) are available. On the contrary, all current methods able to utilize non-Gaussianity in the data (Shimizu et al., 2006; Hoyer et al., 2008) always return only a single graph or a single equivalence class, and so are fundamentally unable to express the degree of certainty attached to that output. In this paper we develop a Bayesian score-based approach able to take advantage of non-Gaussianity when estimating linear acyclic causal models, and we empirically demonstrate that, at least on very modest size networks, its accur...

  12. How to Be Causal: Time, Spacetime and Spectra

    Science.gov (United States)

    Kinsler, Paul

    2011-01-01

    I explain a simple definition of causality in widespread use, and indicate how it links to the Kramers-Kronig relations. The specification of causality in terms of temporal differential equations then shows us the way to write down dynamical models so that their causal nature "in the sense used here" should be obvious to all. To extend existing…

  13. A developmental approach to learning causal models for cyber security

    Science.gov (United States)

    Mugan, Jonathan

    2013-05-01

    To keep pace with our adversaries, we must expand the scope of machine learning and reasoning to address the breadth of possible attacks. One approach is to employ an algorithm to learn a set of causal models that describes the entire cyber network and each host end node. Such a learning algorithm would run continuously on the system and monitor activity in real time. With a set of causal models, the algorithm could anticipate novel attacks, take actions to thwart them, and predict the second-order effects flood of information, and the algorithm would have to determine which streams of that flood were relevant in which situations. This paper will present the results of efforts toward the application of a developmental learning algorithm to the problem of cyber security. The algorithm is modeled on the principles of human developmental learning and is designed to allow an agent to learn about the computer system in which it resides through active exploration. Children are flexible learners who acquire knowledge by actively exploring their environment and making predictions about what they will find,1, 2 and our algorithm is inspired by the work of the developmental psychologist Jean Piaget.3 Piaget described how children construct knowledge in stages and learn new concepts on top of those they already know. Developmental learning allows our algorithm to focus on subsets of the environment that are most helpful for learning given its current knowledge. In experiments, the algorithm was able to learn the conditions for file exfiltration and use that knowledge to protect sensitive files.

  14. Causal beliefs about depression in different cultural groups—what do cognitive psychological theories of causal learning and reasoning predict?

    OpenAIRE

    York eHagmayer; Neele eEngelmann

    2014-01-01

    Cognitive psychological research focuses on causal learning and reasoning while cognitive anthropological and social science research tend to focus on systems of beliefs. Our aim was to explore how these two types of research can inform each other. Cognitive psychological theories (causal model theory and causal Bayes nets) were used to derive predictions for systems of causal beliefs. These predictions were then applied to lay theories of depression as a specific test case. A systematic lite...

  15. Developing Causal Understanding with Causal Maps: The Impact of Total Links, Temporal Flow, and Lateral Position of Outcome Nodes

    Science.gov (United States)

    Jeong, Allan; Lee, Woon Jee

    2012-01-01

    This study examined some of the methodological approaches used by students to construct causal maps in order to determine which approaches help students understand the underlying causes and causal mechanisms in a complex system. This study tested the relationship between causal understanding (ratio of root causes correctly/incorrectly identified,…

  16. Structure and Connectivity Analysis of Financial Complex System Based on G-Causality Network

    Science.gov (United States)

    Xu, Chuan-Ming; Yan, Yan; Zhu, Xiao-Wu; Li, Xiao-Teng; Chen, Xiao-Song

    2013-11-01

    The recent financial crisis highlights the inherent weaknesses of the financial market. To explore the mechanism that maintains the financial market as a system, we study the interactions of U.S. financial market from the network perspective. Applied with conditional Granger causality network analysis, network density, in-degree and out-degree rankings are important indicators to analyze the conditional causal relationships among financial agents, and further to assess the stability of U.S. financial systems. It is found that the topological structure of G-causality network in U.S. financial market changed in different stages over the last decade, especially during the recent global financial crisis. Network density of the G-causality model is much higher during the period of 2007-2009 crisis stage, and it reaches the peak value in 2008, the most turbulent time in the crisis. Ranked by in-degrees and out-degrees, insurance companies are listed in the top of 68 financial institutions during the crisis. They act as the hubs which are more easily influenced by other financial institutions and simultaneously influence others during the global financial disturbance.

  17. Análisis proteómico de Plasmodium, el agente causal de la malaria Proteomic analysis of Plasmodium, the causal agent of Malaria

    Directory of Open Access Journals (Sweden)

    Ivone Castro R

    2009-01-01

    Full Text Available Los plasmodios son protozoarios cuyo complejo ciclo de vida se lleva a cabo en dos hospederos, el vertebrado y el mosquito. La infección de los seres humanos produce la enfermedad conocida como malaria. La secuenciación del genoma de Plasmodium falciparum y el desarrollo de la proteómica han permitido un gran avance en el conocimiento de la biología de este letal parásito. La presente revisión se centra en describir los logros recientes en el estudio del proteoma de Plasmodium falciparum y algunas de las implicaciones en la búsqueda de nuevos fármacos antimaláricos, así como en la generación de vacunas para el control de la enfermedad.Plasmodia are protozoa whose complex life cycle takes place in two different hosts, the vertebrate and the mosquito. The human infection produces the malaria disease. The genome sequence of Plasmodium falciparum and the proteomic tools have enabled a huge advance in knowledge of the biology of this parasite. This review will focus on the recent advances in proteomic studies of Plasmodium falciparum and some implications for the search of new antimalarial drugs as well as vaccines for the control of the disease.

  18. A Causal Theory of Mnemonic Confabulation

    Directory of Open Access Journals (Sweden)

    Sven Bernecker

    2017-07-01

    Full Text Available This paper attempts to answer the question of what defines mnemonic confabulation vis-à-vis genuine memory. The two extant accounts of mnemonic confabulation as “false memory” and as ill-grounded memory are shown to be problematic, for they cannot account for the possibility of veridical confabulation, ill-grounded memory, and well-grounded confabulation. This paper argues that the defining characteristic of mnemonic confabulation is that it lacks the appropriate causal history. In the confabulation case, there is no proper counterfactual dependence of the state of seeming to remember on the corresponding past representation.

  19. A Causal Theory of Mnemonic Confabulation.

    Science.gov (United States)

    Bernecker, Sven

    2017-01-01

    This paper attempts to answer the question of what defines mnemonic confabulation vis-à-vis genuine memory. The two extant accounts of mnemonic confabulation as "false memory" and as ill-grounded memory are shown to be problematic, for they cannot account for the possibility of veridical confabulation, ill-grounded memory, and well-grounded confabulation. This paper argues that the defining characteristic of mnemonic confabulation is that it lacks the appropriate causal history. In the confabulation case, there is no proper counterfactual dependence of the state of seeming to remember on the corresponding past representation.

  20. Bianchi-I cosmology from causal thermodynamics

    CERN Document Server

    Bittencourt, Eduardo; Klippert, Renato

    2016-01-01

    We investigate diagonal Bianchi-I spacetimes in the presence of viscous fluids by using the shear and the anisotropic pressure components as the basic variables, where the viscosity is driven by the (second-order) causal thermodynamics. A few exact solutions are presented, among which we mention the anisotropic versions of de Sitter/anti-de Sitter geometries as well as an asymptotically isotropic spacetime presenting an effective constant cosmic acceleration without any cosmological constant. The qualitative analysis of the solutions for barotropic fluids with linear equations of state suggests that the behaviour is quite general.

  1. On asymmetric causal relationships in Petropolitics

    Directory of Open Access Journals (Sweden)

    Balan Feyza

    2016-01-01

    Full Text Available The aim of this paper is to examine whether the First Law of Petropolitics denominated by Friedman in 2006 is valid for OPEC countries. To do this, this paper analyses the relationship between political risk and oil supply by applying the asymmetric panel causality test suggested by Hatemi-J (2011 to these countries for the period 1984-2014. The results show that the First Law of Petropolitics is valid for Angola, Iraq, Kuwait, Libya, Nigeria, Qatar, Saudi Arabia, and the UAE, given that positive oil supply shocks significantly lead to negative political stability shocks, and negative oil supply shocks significantly lead to positive shocks in political stability.

  2. The semiclassical limit of causal dynamical triangulations

    Energy Technology Data Exchange (ETDEWEB)

    Ambjorn, J., E-mail: ambjorn@nbi.d [Niels Bohr Institute, Copenhagen University, Blegdamsvej 17, DK-2100 Copenhagen O (Denmark); Institute for Theoretical Physics, Utrecht University, Leuvenlaan 4, NL-3584 CE Utrecht (Netherlands); Goerlich, A., E-mail: atg@th.if.uj.edu.p [Institute of Physics, Jagellonian University, Reymonta 4, PL 30-059 Krakow (Poland); Jurkiewicz, J., E-mail: jurkiewicz@th.if.uj.edu.p [Institute of Physics, Jagellonian University, Reymonta 4, PL 30-059 Krakow (Poland); Loll, R., E-mail: r.loll@uu.n [Institute for Theoretical Physics, Utrecht University, Leuvenlaan 4, NL-3584 CE Utrecht (Netherlands); Perimeter Institute for Theoretical Physics, 31 Caroline St. N., Waterloo, Ontario, N2L 2Y5 (Canada); Gizbert-Studnicki, J., E-mail: jakub.gizbert-studnicki@uj.edu.p [Institute of Physics, Jagellonian University, Reymonta 4, PL 30-059 Krakow (Poland); Trzesniewski, T., E-mail: t.trzesniewski@uj.edu.p [Institute of Physics, Jagellonian University, Reymonta 4, PL 30-059 Krakow (Poland)

    2011-08-01

    Previous work has shown that the macroscopic structure of the theory of quantum gravity defined by causal dynamical triangulations (CDT) is compatible with that of a de Sitter universe. After emphasizing the strictly nonperturbative nature of this semiclassical limit we present a detailed study of the three-volume data, which allows us to re-confirm the de Sitter structure, exhibit short-distance discretization effects, and make a first detailed investigation of the presence of higher-order curvature terms in the effective action for the scale factor. Technically, we make use of a novel way of fixing the total four-volume in the simulations.

  3. Toxicology and Epidemiology: Improving the Science with a Framework for Combining Toxicological and Epidemiological Evidence to Establish Causal Inference

    Science.gov (United States)

    Adami, Hans-Olov; Berry, Sir Colin L.; Breckenridge, Charles B.; Smith, Lewis L.; Swenberg, James A.; Trichopoulos, Dimitrios; Weiss, Noel S.; Pastoor, Timothy P.

    2011-01-01

    Historically, toxicology has played a significant role in verifying conclusions drawn on the basis of epidemiological findings. Agents that were suggested to have a role in human diseases have been tested in animals to firmly establish a causative link. Bacterial pathogens are perhaps the oldest examples, and tobacco smoke and lung cancer and asbestos and mesothelioma provide two more recent examples. With the advent of toxicity testing guidelines and protocols, toxicology took on a role that was intended to anticipate or predict potential adverse effects in humans, and epidemiology, in many cases, served a role in verifying or negating these toxicological predictions. The coupled role of epidemiology and toxicology in discerning human health effects by environmental agents is obvious, but there is currently no systematic and transparent way to bring the data and analysis of the two disciplines together in a way that provides a unified view on an adverse causal relationship between an agent and a disease. In working to advance the interaction between the fields of toxicology and epidemiology, we propose here a five-step “Epid-Tox” process that would focus on: (1) collection of all relevant studies, (2) assessment of their quality, (3) evaluation of the weight of evidence, (4) assignment of a scalable conclusion, and (5) placement on a causal relationship grid. The causal relationship grid provides a clear view of how epidemiological and toxicological data intersect, permits straightforward conclusions with regard to a causal relationship between agent and effect, and can show how additional data can influence conclusions of causality. PMID:21561883

  4. Foundational perspectives on causality in large-scale brain networks

    Science.gov (United States)

    Mannino, Michael; Bressler, Steven L.

    2015-12-01

    A profusion of recent work in cognitive neuroscience has been concerned with the endeavor to uncover causal influences in large-scale brain networks. However, despite the fact that many papers give a nod to the important theoretical challenges posed by the concept of causality, this explosion of research has generally not been accompanied by a rigorous conceptual analysis of the nature of causality in the brain. This review provides both a descriptive and prescriptive account of the nature of causality as found within and between large-scale brain networks. In short, it seeks to clarify the concept of causality in large-scale brain networks both philosophically and scientifically. This is accomplished by briefly reviewing the rich philosophical history of work on causality, especially focusing on contributions by David Hume, Immanuel Kant, Bertrand Russell, and Christopher Hitchcock. We go on to discuss the impact that various interpretations of modern physics have had on our understanding of causality. Throughout all this, a central focus is the distinction between theories of deterministic causality (DC), whereby causes uniquely determine their effects, and probabilistic causality (PC), whereby causes change the probability of occurrence of their effects. We argue that, given the topological complexity of its large-scale connectivity, the brain should be considered as a complex system and its causal influences treated as probabilistic in nature. We conclude that PC is well suited for explaining causality in the brain for three reasons: (1) brain causality is often mutual; (2) connectional convergence dictates that only rarely is the activity of one neuronal population uniquely determined by another one; and (3) the causal influences exerted between neuronal populations may not have observable effects. A number of different techniques are currently available to characterize causal influence in the brain. Typically, these techniques quantify the statistical

  5. Causal network inference using biochemical kinetics.

    Science.gov (United States)

    Oates, Chris J; Dondelinger, Frank; Bayani, Nora; Korkola, James; Gray, Joe W; Mukherjee, Sach

    2014-09-01

    Networks are widely used as structural summaries of biochemical systems. Statistical estimation of networks is usually based on linear or discrete models. However, the dynamics of biochemical systems are generally non-linear, suggesting that suitable non-linear formulations may offer gains with respect to causal network inference and aid in associated prediction problems. We present a general framework for network inference and dynamical prediction using time course data that is rooted in non-linear biochemical kinetics. This is achieved by considering a dynamical system based on a chemical reaction graph with associated kinetic parameters. Both the graph and kinetic parameters are treated as unknown; inference is carried out within a Bayesian framework. This allows prediction of dynamical behavior even when the underlying reaction graph itself is unknown or uncertain. Results, based on (i) data simulated from a mechanistic model of mitogen-activated protein kinase signaling and (ii) phosphoproteomic data from cancer cell lines, demonstrate that non-linear formulations can yield gains in causal network inference and permit dynamical prediction and uncertainty quantification in the challenging setting where the reaction graph is unknown. MATLAB R2014a software is available to download from warwick.ac.uk/chrisoates. Supplementary data are available at Bioinformatics online. © The Author 2014. Published by Oxford University Press.

  6. Are bruxism and the bite causally related?

    Science.gov (United States)

    Lobbezoo, F; Ahlberg, J; Manfredini, D; Winocur, E

    2012-07-01

    In the dental profession, the belief that bruxism and dental (mal-)occlusion ('the bite') are causally related is widespread. The aim of this review was to critically assess the available literature on this topic. A PubMed search of the English-language literature, using the query 'Bruxism [Majr] AND (Dental Occlusion [Majr] OR Malocclusion [Majr])', yielded 93 articles, of which 46 papers were finally included in the present review*. Part of the included publications dealt with the possible associations between bruxism and aspects of occlusion, from which it was concluded that neither for occlusal interferences nor for factors related to the anatomy of the oro-facial skeleton, there is any evidence available that they are involved in the aetiology of bruxism. Instead, there is a growing awareness of other factors (viz. psychosocial and behavioural ones) being important in the aetiology of bruxism. Another part of the included papers assessed the possible mediating role of occlusion between bruxism and its purported consequences (e.g. tooth wear, loss of periodontal tissues, and temporomandibular pain and dysfunction). Even though most dentists agree that bruxism may have several adverse effects on the masticatory system, for none of these purported adverse effects, evidence for a mediating role of occlusion and articulation has been found to date. Hence, based on this review, it should be concluded that to date, there is no evidence whatsoever for a causal relationship between bruxism and the bite. © 2012 Blackwell Publishing Ltd.

  7. Evidence for online processing during causal learning.

    Science.gov (United States)

    Liu, Pei-Pei; Luhmann, Christian C

    2015-03-01

    Many models of learning describe both the end product of learning (e.g., causal judgments) and the cognitive mechanisms that unfold on a trial-by-trial basis. However, the methods employed in the literature typically provide only indirect evidence about the unfolding cognitive processes. Here, we utilized a simultaneous secondary task to measure cognitive processing during a straightforward causal-learning task. The results from three experiments demonstrated that covariation information is not subject to uniform cognitive processing. Instead, we observed systematic variation in the processing dedicated to individual pieces of covariation information. In particular, observations that are inconsistent with previously presented covariation information appear to elicit greater cognitive processing than do observations that are consistent with previously presented covariation information. In addition, the degree of cognitive processing appears to be driven by learning per se, rather than by nonlearning processes such as memory and attention. Overall, these findings suggest that monitoring learning processes at a finer level may provide useful psychological insights into the nature of learning.

  8. Causal-Explanatory Pluralism: How Intentions, Functions, and Mechanisms Influence Causal Ascriptions

    Science.gov (United States)

    Lombrozo, Tania

    2010-01-01

    Both philosophers and psychologists have argued for the existence of distinct kinds of explanations, including teleological explanations that cite functions or goals, and mechanistic explanations that cite causal mechanisms. Theories of causation, in contrast, have generally been unitary, with dominant theories focusing either on counterfactual…

  9. God Does Not Play Dice: Causal Determinism and Preschoolers' Causal Inferences

    Science.gov (United States)

    Schulz, Laura E.; Sommerville, Jessica

    2006-01-01

    Three studies investigated children's belief in causal determinism. If children are determinists, they should infer unobserved causes whenever observed causes appear to act stochastically. In Experiment 1, 4-year-olds saw a stochastic generative cause and inferred the existence of an unobserved inhibitory cause. Children traded off inferences…

  10. Quantum causality conceptual issues in the causal theory of quantum mechanics

    CERN Document Server

    Riggs, Peter J; French, Steven RD

    2009-01-01

    This is a treatise devoted to the foundations of quantum physics and the role that causality plays in the microscopic world governed by the laws of quantum mechanics. The book is controversial and will engender some lively debate on the various issues raised.

  11. Agent Based Reasoning in Multilevel Flow Modeling

    DEFF Research Database (Denmark)

    Lind, Morten; Zhang, Xinxin

    2012-01-01

    to launch the MFM Workbench into an agent based environment, which can complement disadvantages of the original software. The agent-based MFM Workbench is centered on a concept called “Blackboard System” and use an event based mechanism to arrange the reasoning tasks. This design will support the new......Multilevel Flow Modeling (MFM) is a modeling method used for modeling complex industrial plant. Currently, MFM is supported with a standalone software tool called MFM Workbench, which is equipped with causal-relation analysis and other functionalities. The aim of this paper is to offer a new design...

  12. The role of counterfactual theory in causal reasoning.

    Science.gov (United States)

    Maldonado, George

    2016-10-01

    In this commentary I review the fundamentals of counterfactual theory and its role in causal reasoning in epidemiology. I consider if counterfactual theory dictates that causal questions must be framed in terms of well-defined interventions. I conclude that it does not. I hypothesize that the interventionist approach to causal inference in epidemiology stems from elevating the randomized trial design to the gold standard for thinking about causal inference. I suggest that instead the gold standard we should use for thinking about causal inference in epidemiology is the thought experiment that, for example, compares an actual disease frequency under one exposure level with a counterfactual disease frequency under a different exposure level (as discussed in Greenland and Robins (1986) and Maldonado and Greenland (2002)). I also remind us that no method should be termed "causal" unless it addresses the effect of other biases in addition to the problem of confounding. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Restrictions for the causal inferences in an interferometric system

    Science.gov (United States)

    Rossi, R.

    2017-07-01

    Causal discovery algorithms allow for the inference of causal structures from probabilistic relations of random variables. A natural field for the application of this tool is quantum mechanics, where a long-standing debate about the role of causality in the theory has flourished since its early days. In this paper, a causal discovery algorithm is applied in the search for causal models to describe a quantum version of Wheeler's delayed-choice experiment. The outputs explicitly show the restrictions for the introduction of classical concepts in this system. The exclusion of models with two hidden variables is one of them. A consequence of such a constraint is the impossibility to construct a causal model that avoids superluminal causation and assumes an objective view of the wave and particle properties simultaneously.

  14. Causality and Responsibility for Formal Verification and Beyond

    Directory of Open Access Journals (Sweden)

    Hana Chockler

    2016-08-01

    Full Text Available The theory of actual causality, defined by Halpern and Pearl, and its quantitative measure - the degree of responsibility - was shown to be extremely useful in various areas of computer science due to a good match between the results it produces and our intuition. In this paper, I describe the applications of causality to formal verification, namely, explanation of counterexamples, refinement of coverage metrics, and symbolic trajectory evaluation. I also briefly discuss recent applications of causality to legal reasoning.

  15. Exploring Torus Universes in Causal Dynamical Triangulations

    DEFF Research Database (Denmark)

    Budd, Timothy George; Loll, R.

    2013-01-01

    Motivated by the search for new observables in nonperturbative quantum gravity, we consider Causal Dynamical Triangulations (CDT) in 2+1 dimensions with the spatial topology of a torus. This system is of particular interest, because one can study not only the global scale factor, but also global ....... Apart from setting the stage for the analysis of shape dynamics on the torus, the new set-up highlights the role of nontrivial boundaries and topology....... shape variables in the presence of arbitrary quantum fluctuations of the geometry. Our initial investigation focusses on the dynamics of the scale factor and uncovers a qualitatively new behaviour, which leads us to investigate a novel type of boundary conditions for the path integral. Comparing large...

  16. Causal Dynamical Triangulations in Four Dimensions

    Science.gov (United States)

    Görlich, Andrzej

    2011-11-01

    Recent results obtained within a non-perturbative approach to quantum gravity based on the method of four-dimensional Causal Dynamical Triangulations are described. The phase diagram of the model consists of three phases. In the physically most interesting phase, the time-translational symmetry is spontaneously broken. Calculations of expectation values required introducing procedures taking into account the inhomogeneity of configurations. It was shown that the dynamically emerged four-dimensional background geometry corresponds to a Euclidean de Sitter space and reveals no fractality at large distances. Measurements of the covariance matrix of scale factor fluctuations allowed to reconstruct the effective action, which remained in agreement with the discrete minisuperspace action. Values of the Hausdorff dimension and spectral dimension of three-dimensional spatial slices suggest their fractal nature, which was confirmed by a direct analysis of triangulation structure. The Monte Carlo algorithm used to obtain presented results is described.

  17. Fabry's disease and psychosis: causality or coincidence?

    Science.gov (United States)

    Gairing, S; Wiest, R; Metzler, S; Theodoridou, A; Hoff, P

    2011-01-01

    A 21-year-old female with Fabry's disease (FD) presented acute psychotic symptoms such as delusions, auditory hallucinations and formal thought disorders. Since the age of 14, she had suffered from various psychiatric symptoms increasing in frequency and intensity. We considered the differential diagnoses of prodromal symptoms of schizophrenia and organic schizophrenia-like disorder. Routine examinations including cognitive testing, electroencephalography and structural magnetic resonance imaging revealed no pathological findings. Additional structural and functional imaging demonstrated a minor CNS involvement of FD, yet without functional limitations. In summary our examination results support the thesis that in the case of our patient a mere coincidence of FD and psychotic symptoms is more likely than a causal connection. Copyright © 2011 S. Karger AG, Basel.

  18. Flux Analysis in Process Models via Causality

    Directory of Open Access Journals (Sweden)

    Ozan Kahramanoğulları

    2010-02-01

    Full Text Available We present an approach for flux analysis in process algebra models of biological systems. We perceive flux as the flow of resources in stochastic simulations. We resort to an established correspondence between event structures, a broadly recognised model of concurrency, and state transitions of process models, seen as Petri nets. We show that we can this way extract the causal resource dependencies in simulations between individual state transitions as partial orders of events. We propose transformations on the partial orders that provide means for further analysis, and introduce a software tool, which implements these ideas. By means of an example of a published model of the Rho GTP-binding proteins, we argue that this approach can provide the substitute for flux analysis techniques on ordinary differential equation models within the stochastic setting of process algebras.

  19. Equity Theory Ratios as Causal Schemas.

    Science.gov (United States)

    Arvanitis, Alexios; Hantzi, Alexandra

    2016-01-01

    Equity theory approaches justice evaluations based on ratios of exchange inputs to exchange outcomes. Situations are evaluated as just if ratios are equal and unjust if unequal. We suggest that equity ratios serve a more fundamental cognitive function than the evaluation of justice. More particularly, we propose that they serve as causal schemas for exchange outcomes, that is, they assist in determining whether certain outcomes are caused by inputs of other people in the context of an exchange process. Equality or inequality of ratios in this sense points to an exchange process. Indeed, Study 1 shows that different exchange situations, such as disproportional or balanced proportional situations, create perceptions of give-and-take on the basis of equity ratios. Study 2 shows that perceptions of justice are based more on communicatively accepted rules of interaction than equity-based evaluations, thereby offering a distinction between an attribution and an evaluation cognitive process for exchange outcomes.

  20. Causal attribution among women with breast cancer

    Directory of Open Access Journals (Sweden)

    Ana Carolina W. B. Peuker

    2016-01-01

    Full Text Available Abstract Causal attribution among women with breast cancer was studied. The study included 157 women outpatients with breast cancer. A form for sociodemographic and clinical data and the Revised Illness Perception Questionnaire (IPQ-R were used. The results showed that women attributed breast cancer primarily to psychological causes, which does not correspond to known multifactorial causes validated by the scientific community. Providing high quality, patient-centered care requires sensitivity to breast cancer women’s beliefs about the causes of their cancer and awareness of how it can influence patient’s health behaviors after diagnosis. If women with breast cancer attribute the illness to modifiable factors then they can keep a healthy lifestyle, improving their recovery and decrease the probability of cancer recurrence after diagnosis.

  1. Equity Theory Ratios as Causal Schemas

    Directory of Open Access Journals (Sweden)

    Alexios Arvanitis

    2016-08-01

    Full Text Available Equity theory approaches justice evaluations based on ratios of exchange inputs to exchange outcomes. Situations are evaluated as just if ratios are equal and unjust if unequal. We suggest that equity ratios serve a more fundamental cognitive function than the evaluation of justice. More particularly, we propose that they serve as causal schemas for exchange outcomes, that is, they assist in determining whether certain outcomes are caused by inputs of other people in the context of an exchange process. Equality or inequality of ratios in this sense points to an exchange process. Indeed, Study 1 shows that different exchange situations, such as disproportional or balanced proportional situations, create perceptions of give-and-take on the basis of equity ratios. Study 2 shows that perceptions of justice are based more on communicatively accepted rules of interaction than equity-based evaluations, thereby offering a distinction between an attribution and an evaluation cognitive process for exchange outcomes.

  2. Causality Constraints in Conformal Field Theory

    CERN Multimedia

    CERN. Geneva

    2015-01-01

    Causality places nontrivial constraints on QFT in Lorentzian signature, for example fixing the signs of certain terms in the low energy Lagrangian. In d-dimensional conformal field theory, we show how such constraints are encoded in crossing symmetry of Euclidean correlators, and derive analogous constraints directly from the conformal bootstrap (analytically). The bootstrap setup is a Lorentzian four-point function corresponding to propagation through a shockwave. Crossing symmetry fixes the signs of certain log terms that appear in the conformal block expansion, which constrains the interactions of low-lying operators. As an application, we use the bootstrap to rederive the well known sign constraint on the (∂φ)4 coupling in effective field theory, from a dual CFT. We also find constraints on theories with higher spin conserved currents. Our analysis is restricted to scalar correlators, but we argue that similar methods should also impose nontrivial constraints on the interactions of spinni...

  3. Trading Agents

    CERN Document Server

    Wellman, Michael

    2011-01-01

    Automated trading in electronic markets is one of the most common and consequential applications of autonomous software agents. Design of effective trading strategies requires thorough understanding of how market mechanisms operate, and appreciation of strategic issues that commonly manifest in trading scenarios. Drawing on research in auction theory and artificial intelligence, this book presents core principles of strategic reasoning that apply to market situations. The author illustrates trading strategy choices through examples of concrete market environments, such as eBay, as well as abst

  4. The causal relationship between need for cognition and advertising recall

    National Research Council Canada - National Science Library

    Kuo, Jung-Chung; Horng, Der-Juinn; Lin, Chin-Lung

    2012-01-01

    Using a factorial experiment design, we investigated the causal relationship between personality factors and cognitive responses, as well as the relationship between cognitive responses and purchasing intentions...

  5. Worlds of Events: Deduction with Partial Knowledge about Causality

    Directory of Open Access Journals (Sweden)

    Seyed Hossein Haeri

    2016-08-01

    Full Text Available Interactions between internet users are mediated by their devices and the common support infrastructure in data centres. Keeping track of causality amongst actions that take place in this distributed system is key to provide a seamless interaction where effects follow causes. Tracking causality in large scale interactions is difficult due to the cost of keeping large quantities of metadata; even more challenging when dealing with resource-limited devices. In this paper, we focus on keeping partial knowledge on causality and address deduction from that knowledge. We provide the first proof-theoretic causality modelling for distributed partial knowledge. We prove computability and consistency results. We also prove that the partial knowledge gives rise to a weaker model than classical causality. We provide rules for offline deduction about causality and refute some related folklore. We define two notions of forward and backward bisimilarity between devices, using which we prove two important results. Namely, no matter the order of addition/removal, two devices deduce similarly about causality so long as: (1 the same causal information is fed to both. (2 they start bisimilar and erase the same causal information. Thanks to our establishment of forward and backward bisimilarity, respectively, proofs of the latter two results work by simple induction on length.

  6. Granger Causality and Transfer Entropy Are Equivalent for Gaussian Variables

    Science.gov (United States)

    Barnett, Lionel; Barrett, Adam B.; Seth, Anil K.

    2009-12-01

    Granger causality is a statistical notion of causal influence based on prediction via vector autoregression. Developed originally in the field of econometrics, it has since found application in a broader arena, particularly in neuroscience. More recently transfer entropy, an information-theoretic measure of time-directed information transfer between jointly dependent processes, has gained traction in a similarly wide field. While it has been recognized that the two concepts must be related, the exact relationship has until now not been formally described. Here we show that for Gaussian variables, Granger causality and transfer entropy are entirely equivalent, thus bridging autoregressive and information-theoretic approaches to data-driven causal inference.

  7. Choice of Units and the Causal Markov Condition

    Science.gov (United States)

    Zhang, Jiji; Spirtes, Peter

    2014-03-01

    Elliott Sober's well-known challenge to the principle of the common cause -- and to its generalization, the causal Markov condition -- appeals to the apparent positive correlation between two causally unconnected quantities: Venetian sea levels and British bread prices. In this paper we examine Kevin Hoover's and Daniel Steel's opposite evaluations of Sober's case. We argue that the difference in their assessments results from a difference in their choice of units and populations for statistical modeling. Our analysis suggests yet another diagnosis of Sober's counterexample: the failure of the causal Markov condition in the population chosen by Sober and Steel is due to the presence of causal relations that hold between the relevant properties across units. Such inter-unit causation is left unrepresented in causal models congenial to statistical analysis, because statistics does not deal with inter-unit relationships once the units are fixed. Accordingly, the causal Markov condition is formulated in terms of causal structures that depict intra-unit causal relations only. It is therefore worth highlighting a methodological principle for causal inference: the units should be so chosen that they do not interfere with each other, a principle that, fortunately, is often observed in practice.

  8. Testing frequency-domain causality in multivariate time series.

    Science.gov (United States)

    Faes, Luca; Porta, Alberto; Nollo, Giandomenico

    2010-08-01

    We introduce a new hypothesis-testing framework, based on surrogate data generation, to assess in the frequency domain, the concept of causality among multivariate (MV) time series. The approach extends the traditional Fourier transform (FT) method for generating surrogate data in a MV process and adapts it to the specific issue of causality. It generates causal FT (CFT) surrogates with FT modulus taken from the original series, and FT phase taken from a set of series with causal interactions set to zero over the direction of interest and preserved over all other directions. Two different zero-setting procedures, acting on the parameters of a MV autoregressive (MVAR) model fitted on the original series, were used to test the null hypotheses of absence of direct causal influence (CFTd surrogates) and of full (direct and indirect) causal influence (CFTf surrogates), respectively. CFTf and CFTd surrogates were utilized in combination with the directed coherence (DC) and the partial DC (PDC) spectral causality estimators, respectively. Simulations reproducing different causality patterns in linear MVAR processes demonstrated the better accuracy of CFTf and CFTd surrogates with respect to traditional FT surrogates. Application on real MV biological data measured from healthy humans, i.e., heart period, arterial pressure, and respiration variability, as well as multichannel EEG signals, showed that CFT surrogates disclose causal patterns in accordance with expected cardiorespiratory and neurophysiological mechanisms.

  9. A general, multivariate definition of causal effects in epidemiology.

    Science.gov (United States)

    Flanders, W Dana; Klein, Mitchel

    2015-07-01

    Population causal effects are often defined as contrasts of average individual-level counterfactual outcomes, comparing different exposure levels. Common examples include causal risk difference and risk ratios. These and most other examples emphasize effects on disease onset, a reflection of the usual epidemiological interest in disease occurrence. Exposure effects on other health characteristics, such as prevalence or conditional risk of a particular disability, can be important as well, but contrasts involving these other measures may often be dismissed as non-causal. For example, an observed prevalence ratio might often viewed as an estimator of a causal incidence ratio and hence subject to bias. In this manuscript, we provide and evaluate a definition of causal effects that generalizes those previously available. A key part of the generalization is that contrasts used in the definition can involve multivariate, counterfactual outcomes, rather than only univariate outcomes. An important consequence of our generalization is that, using it, one can properly define causal effects based on a wide variety of additional measures. Examples include causal prevalence ratios and differences and causal conditional risk ratios and differences. We illustrate how these additional measures can be useful, natural, easily estimated, and of public health importance. Furthermore, we discuss conditions for valid estimation of each type of causal effect, and how improper interpretation or inferences for the wrong target population can be sources of bias.

  10. PROBLEMATIC ISSUES OF CAUSAL TREATMENT FOR URINARY TRACT INFECTIONS IN CHILDREN

    Directory of Open Access Journals (Sweden)

    V. I. Kirillov

    2016-01-01

    Full Text Available The review gives data on shortcomings in the antimicrobial measures that are associated with the defects in the effective treatment of urinary system infections, such as the high risk of disease relapses and the stable proportion of secondary pyelonephritis among the causes of chronic renal failure. The vulnerability of this approach is to accelerate the rate of acquiring the resistance of uropathogens to the currently available antibiotics that may also have a number of side effects, including those involved in the pathogenesis of urinary tract infections. Difficulties in conducting adequate causal therapy are also associated with some subjective factors that largely hamper the personalized diagnosis of diseases of causative agents.

  11. Pseudomonads and symbiotic micro-organisms as biocontrol agents ...

    African Journals Online (AJOL)

    Experiments were undertaken to assess the antagonistic aptitude of Pseudomonas spp. alone or associated with mycorrhizal fungi on Pythium aphanidermaturm, the causal agent of seedlings dampingoff and stem rot of cowpea (Vigna unguiculata L. Walp). Evaluation was made using selected strains of pseudomonad ...

  12. Radioprotective Agents

    Directory of Open Access Journals (Sweden)

    Ilker Kelle

    2008-01-01

    Full Text Available Since1949, a great deal of research has been carried out on the radioprotective activity of various chemical substances. Thiol compounds, compounds which contain –SH radical, different classes of pharmacological agents and other compounds such as vitamine C and WR-2721 have been shown to reduce mortality when administered prior to exposure to a lethal dose of radiation. Recently, honey bee venom as well as that of its components melittin and histamine have shown to be valuable in reduction of radiation-induced damage and also provide prophylactic alternative treatment for serious side effects related with radiotherapy. It has been suggested that the radioprotective activity of bee venom components is related with the stimulation of the hematopoetic system.

  13. Thinking Fast and Slow about Causality: Response to Palinkas

    Science.gov (United States)

    Marsh, Jeanne C.

    2014-01-01

    Larry Palinkas advances the developing science of social work by providing an explanation of how social science research methods, both qualitative and quantitative, can improve our capacity to draw casual inferences. Understanding causal relations and making causal inferences--with the promise of being able to predict and control outcomes--is…

  14. Cause and Event: Supporting Causal Claims through Logistic Models

    Science.gov (United States)

    O'Connell, Ann A.; Gray, DeLeon L.

    2011-01-01

    Efforts to identify and support credible causal claims have received intense interest in the research community, particularly over the past few decades. In this paper, we focus on the use of statistical procedures designed to support causal claims for a treatment or intervention when the response variable of interest is dichotomous. We identify…

  15. Forces and Motion: How Young Children Understand Causal Events

    Science.gov (United States)

    Goksun, Tilbe; George, Nathan R.; Hirsh-Pasek, Kathy; Golinkoff, Roberta M.

    2013-01-01

    How do children evaluate complex causal events? This study investigates preschoolers' representation of "force dynamics" in causal scenes, asking whether (a) children understand how single and dual forces impact an object's movement and (b) this understanding varies across cause types (Cause, Enable, Prevent). Three-and-a half- to…

  16. Computer Use, Confidence, Attitudes, and Knowledge: A Causal Analysis.

    Science.gov (United States)

    Levine, Tamar; Donitsa-Schmidt, Smadar

    1998-01-01

    Introduces a causal model which links measures of computer experience, computer-related attitudes, computer-related confidence, and perceived computer-based knowledge. The causal model suggests that computer use has a positive effect on perceived computer self-confidence, as well as on computer-related attitudes. Questionnaires were administered…

  17. Trygve Haavelmo and the Emergence of Causal Calculus

    Science.gov (United States)

    2014-06-01

    terms, Haavelmo rejected the then-ruling paradigm that parameters are conveyors of statistical information and prepared the ground for the causal...EXPERIMENTALISTS” DEBATE The Spring 2010 issue of the Journal of Econometric Perspectives (Vol. 24, No. 2) presented an interesting discussion on causal

  18. Causality of plasma permittivity with loss and restoring terms

    Science.gov (United States)

    Cockrell, C. R.

    1989-01-01

    The causality of the complex permittivity for a plasma model in which both loss and restoring terms are included is shown. Discussions as to what occurs in this causality property when the loss and restoring terms vanish are presented. Results are shown to agree with earlier work.

  19. Child Care Subsidy Use and Child Development: Potential Causal Mechanisms

    Science.gov (United States)

    Hawkinson, Laura E.

    2011-01-01

    Research using an experimental design is needed to provide firm causal evidence on the impacts of child care subsidy use on child development, and on underlying causal mechanisms since subsidies can affect child development only indirectly via changes they cause in children's early experiences. However, before costly experimental research is…

  20. Causal Inference Using Graphical Models with the R Package pcalg

    Directory of Open Access Journals (Sweden)

    Markus Kalisch

    2012-04-01

    Full Text Available The pcalg package for R can be used for the following two purposes: Causal structure learning and estimation of causal effects from observational data. In this document, we give a brief overview of the methodology, and demonstrate the package’s functionality in both toy examples and applications.

  1. La mente es una estructura causal: el funcionalismo teorico

    OpenAIRE

    Villanueva, Enrique

    2000-01-01

    Causal functionalism of the sort David Lewis advocates is subject to examination and criticism. This brand of functionalism is brought to bear on the ontological question what are psychological properties? Answering that they are causal theoretical properties whose natures will be empirically discovered eventually.

  2. New higher-order transition in causal dynamical triangulations

    NARCIS (Netherlands)

    Ambjorn, J.; Coumbe, D.; Gizbert-Studnicki, J.; Gorlich, A.; Jurkiewicz, J.

    2017-01-01

    We reinvestigate the recently discovered bifurcation phase transition in causal dynamical triangulations and provide further evidence that it is a higher-order transition. We also investigate the impact of introducing matter in the form of massless scalar fields to causal dynamical triangulations.

  3. Is there a causal relationship between alcohol and HIV? Implications ...

    African Journals Online (AJOL)

    There is now conclusive evidence of a causal linkage between heavy drinking patterns and/or alcohol use disorders and the worsening of the disease course for HIV. However, while alcohol usage is consistently associated with the prevalence and incidence of HIV, further research is needed to substantiate causality in ...

  4. Ends, Principles, and Causal Explanation in Educational Justice

    Science.gov (United States)

    Dum, Jenn

    2017-01-01

    Many principles characterize educational justice in terms of the relationship between educational inputs, outputs and distributive standards. Such principles depend upon the "causal pathway view" of education. It is implicit in this view that the causally effective aspects of education can be understood as separate from the normative…

  5. The Development of Causal Structure without a Language Model

    Science.gov (United States)

    Rissman, Lilia; Goldin-Meadow, Susan

    2017-01-01

    Across a diverse range of languages, children proceed through similar stages in their production of causal language: their initial verbs lack internal causal structure, followed by a period during which they produce causative overgeneralizations, indicating knowledge of a productive causative rule. We asked in this study whether a child not…

  6. Causal Discourse Analyzer: Improving Automated Feedback on Academic ESL Writing

    Science.gov (United States)

    Chukharev-Hudilainen, Evgeny; Saricaoglu, Aysel

    2016-01-01

    Expressing causal relations plays a central role in academic writing. While it is important that writing instructors assess and provide feedback on learners' causal discourse, it could be a very time-consuming task. In this respect, automated writing evaluation (AWE) tools may be helpful. However, to date, there have been no AWE tools capable of…

  7. Developmental Changes in Causal Supports for Word Learning

    Science.gov (United States)

    Booth, Amy E.; Alvarez, Aubry

    2015-01-01

    This work explores whether the facilitative effect of causal information on preschoolers' word and descriptive fact learning persists in school-age children. Twenty-three 5-year-olds just beginning school and 23 6- to 7-year-olds who had accumulated over a year of schooling were taught novel words along with descriptions of causally rich,…

  8. Identification of Mixed Causal-Noncausal Models in Finite Samples

    NARCIS (Netherlands)

    Hecq, Alain; Lieb, Lenard; Telg, Sean

    2016-01-01

    Gouriéroux and Zakoïan (2013) propose to use noncausal models to parsimoniously capture nonlinear features often observed in financial time series and in particular bubble phenomena. In order to distinguish causal autoregressive processes from purely noncausal or mixed causal-noncausal ones, one has

  9. Statistical causal inferences and their applications in public health research

    CERN Document Server

    Wu, Pan; Chen, Ding-Geng

    2016-01-01

    This book compiles and presents new developments in statistical causal inference. The accompanying data and computer programs are publicly available so readers may replicate the model development and data analysis presented in each chapter. In this way, methodology is taught so that readers may implement it directly. The book brings together experts engaged in causal inference research to present and discuss recent issues in causal inference methodological development. This is also a timely look at causal inference applied to scenarios that range from clinical trials to mediation and public health research more broadly. In an academic setting, this book will serve as a reference and guide to a course in causal inference at the graduate level (Master's or Doctorate). It is particularly relevant for students pursuing degrees in Statistics, Biostatistics and Computational Biology. Researchers and data analysts in public health and biomedical research will also find this book to be an important reference.

  10. Children use temporal cues to learn causal directionality.

    Science.gov (United States)

    Rottman, Benjamin M; Kominsky, Jonathan F; Keil, Frank C

    2014-04-01

    The ability to learn the direction of causal relations is critical for understanding and acting in the world. We investigated how children learn causal directionality in situations in which the states of variables are temporally dependent (i.e., autocorrelated). In Experiment 1, children learned about causal direction by comparing the states of one variable before versus after an intervention on another variable. In Experiment 2, children reliably inferred causal directionality merely from observing how two variables change over time; they interpreted Y changing without a change in X as evidence that Y does not influence X. Both of these strategies make sense if one believes the variables to be temporally dependent. We discuss the implications of these results for interpreting previous findings. More broadly, given that many real-world environments are characterized by temporal dependency, these results suggest strategies that children may use to learn the causal structure of their environments. Copyright © 2013 Cognitive Science Society, Inc.

  11. Global techniques, dual mass, and causality violation

    Energy Technology Data Exchange (ETDEWEB)

    Magnon, A.

    1986-04-01

    A mathematical framework is presented for the description of (magnetic) monopoles or their gravitational analogs. Using Penrose's global techniques, a proof of a theorem to the effect that, for vacuum space-times with wormhole and an everywhere timelike and complete Killing vector field, the topology must be that of a principal S/sup 1/ fiber bundle over S/sup 2/ x R (topology of the manifold of orbits of the stationary Killing vector field) if the dual mass (the gravitational analog of the magnetic monopole) does not vanish, is presented. Hence the presence of this magnetic charge induces a causality violation: it is shown that it measures the number of windings of the space-time bundle around its fiber, or the periodicity of the timelike closed loops. If, in addition, the manifold of orbits of the stationary Killing field is asymptotically flat, or if a rotational Killing field is present, the resulting expressions of the dual mass reinsure the fact that it should be viewed as a monopole source of angular momentum. The NUT solution is presented as an example of space-time exhibiting the above features. The role of dual mass solutions in quantum gravity is considered.

  12. A new test of multivariate nonlinear causality.

    Science.gov (United States)

    Bai, Zhidong; Hui, Yongchang; Jiang, Dandan; Lv, Zhihui; Wong, Wing-Keung; Zheng, Shurong

    2018-01-01

    The multivariate nonlinear Granger causality developed by Bai et al. (2010) (Mathematics and Computers in simulation. 2010; 81: 5-17) plays an important role in detecting the dynamic interrelationships between two groups of variables. Following the idea of Hiemstra-Jones (HJ) test proposed by Hiemstra and Jones (1994) (Journal of Finance. 1994; 49(5): 1639-1664), they attempt to establish a central limit theorem (CLT) of their test statistic by applying the asymptotical property of multivariate U-statistic. However, Bai et al. (2016) (2016; arXiv: 1701.03992) revisit the HJ test and find that the test statistic given by HJ is NOT a function of U-statistics which implies that the CLT neither proposed by Hiemstra and Jones (1994) nor the one extended by Bai et al. (2010) is valid for statistical inference. In this paper, we re-estimate the probabilities and reestablish the CLT of the new test statistic. Numerical simulation shows that our new estimates are consistent and our new test performs decent size and power.

  13. Averaged null energy condition from causality

    Science.gov (United States)

    Hartman, Thomas; Kundu, Sandipan; Tajdini, Amirhossein

    2017-07-01

    Unitary, Lorentz-invariant quantum field theories in flat spacetime obey mi-crocausality: commutators vanish at spacelike separation. For interacting theories in more than two dimensions, we show that this implies that the averaged null energy, ∫ duT uu , must be non-negative. This non-local operator appears in the operator product expansion of local operators in the lightcone limit, and therefore contributes to n-point functions. We derive a sum rule that isolates this contribution and is manifestly positive. The argument also applies to certain higher spin operators other than the stress tensor, generating an infinite family of new constraints of the form ∫ duX uuu··· u ≥ 0. These lead to new inequalities for the coupling constants of spinning operators in conformal field theory, which include as special cases (but are generally stronger than) the existing constraints from the lightcone bootstrap, deep inelastic scattering, conformal collider methods, and relative entropy. We also comment on the relation to the recent derivation of the averaged null energy condition from relative entropy, and suggest a more general connection between causality and information-theoretic inequalities in QFT.

  14. Body selectivity in occipitotemporal cortex: Causal evidence.

    Science.gov (United States)

    Downing, Paul E; Peelen, Marius V

    2016-03-01

    Perception of others' bodies provides information that is useful for a number of important social-cognitive processes. Evidence from neuroimaging methods has identified focal cortical regions that are highly selective for perceiving bodies and body parts, including the extrastriate body area (EBA) and fusiform body area (FBA). Our understanding of the functional properties of these regions, and their causal contributions to behavior, has benefitted from the study of neuropsychological patients and particularly from investigations using transcranial magnetic stimulation (TMS). We review this evidence, focusing on TMS studies that are revealing of how (and when) activity in EBA contributes to detecting people in natural scenes; to resolving their body shape, movements, actions, individual parts, and identities; and to guiding goal-directed behavior. These findings are considered in reference to a framework for body perception in which the patterns of neural activity in EBA and FBA jointly serve to make explicit the elements of the visual scene that correspond to the body and its parts. These representations are modulated by other sources of information such as prior knowledge, and are shared with wider brain networks involved in many aspects of social cognition. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Physics Without Causality — Theory and Evidence

    Science.gov (United States)

    Shoup, Richard

    2006-10-01

    The principle of cause and effect is deeply rooted in human experience, so much so that it is routinely and tacitly assumed throughout science, even by scientists working in areas where time symmetry is theoretically ingrained, as it is in both classical and quantum physics. Experiments are said to cause their results, not the other way around. In this informal paper, we argue that this assumption should be replaced with a more general notion of mutual influence — bi-directional relations or constraints on joint values of two or more variables. From an analysis based on quantum entropy, it is proposed that quantum measurement is a unitary three-interaction, with no collapse, no fundamental randomness, and no barrier to backward influence. Experimental results suggesting retrocausality are seen frequently in well-controlled laboratory experiments in parapsychology and elsewhere, especially where a random element is included. Certain common characteristics of these experiments give the appearance of contradicting well-established physical laws, thus providing an opportunity for deeper understanding and important clues that must be addressed by any explanatory theory. We discuss how retrocausal effects and other anomalous phenomena can be explained without major injury to existing physical theory. A modified quantum formalism can give new insights into the nature of quantum measurement, randomness, entanglement, causality, and time.

  16. Automaticity: Componential, Causal, and Mechanistic Explanations.

    Science.gov (United States)

    Moors, Agnes

    2016-01-01

    The review first discusses componential explanations of automaticity, which specify non/automaticity features (e.g., un/controlled, un/conscious, non/efficient, fast/slow) and their interrelations. Reframing these features as factors that influence processes (e.g., goals, attention, and time) broadens the range of factors that can be considered (e.g., adding stimulus intensity and representational quality). The evidence reviewed challenges the view of a perfect coherence among goals, attention, and consciousness, and supports the alternative view that (a) these and other factors influence the quality of representations in an additive way (e.g., little time can be compensated by extra attention or extra stimulus intensity) and that (b) a first threshold of this quality is required for unconscious processing and a second threshold for conscious processing. The review closes with a discussion of causal explanations of automaticity, which specify factors involved in automatization such as repetition and complexity, and a discussion of mechanistic explanations, which specify the low-level processes underlying automatization.

  17. On Optimum Causal Cognitive Spectrum Reutilization Strategy

    CERN Document Server

    Haghighi, Kasra; Agrell, Erik

    2011-01-01

    In this paper we study opportunistic transmission strategies for cognitive radios (CR) in which causal noisy observation from a primary user(s) (PU) state is available. PU is assumed to be operating in a slotted manner, according to a two-state Markov model. The objective is to maximize utilization ratio (UR), i.e., relative number of the PU-idle slots that are used by CR, subject to interference ratio (IR), i.e., relative number of the PU-active slots that are used by CR, below a certain level. We introduce an a-posteriori LLR-based cognitive transmission strategy and show that this strategy is optimum in the sense of maximizing UR given a certain maximum allowed IR. Two methods for calculating threshold for this strategy in practical situations are presented. One of them performs well in higher SNRs but might have too large IR at low SNRs and low PU activity levels, and the other is proven to never violate the allowed IR at the price of a reduced UR. In addition, an upper-bound for the UR of any CR strategy...

  18. Reconstructing Causal Biological Networks through Active Learning.

    Directory of Open Access Journals (Sweden)

    Hyunghoon Cho

    Full Text Available Reverse-engineering of biological networks is a central problem in systems biology. The use of intervention data, such as gene knockouts or knockdowns, is typically used for teasing apart causal relationships among genes. Under time or resource constraints, one needs to carefully choose which intervention experiments to carry out. Previous approaches for selecting most informative interventions have largely been focused on discrete Bayesian networks. However, continuous Bayesian networks are of great practical interest, especially in the study of complex biological systems and their quantitative properties. In this work, we present an efficient, information-theoretic active learning algorithm for Gaussian Bayesian networks (GBNs, which serve as important models for gene regulatory networks. In addition to providing linear-algebraic insights unique to GBNs, leading to significant runtime improvements, we demonstrate the effectiveness of our method on data simulated with GBNs and the DREAM4 network inference challenge data sets. Our method generally leads to faster recovery of underlying network structure and faster convergence to final distribution of confidence scores over candidate graph structures using the full data, in comparison to random selection of intervention experiments.

  19. Causal beliefs about depression in different cultural groups – What do cognitive psychological theories of causal learning and reasoning predict?

    Directory of Open Access Journals (Sweden)

    York eHagmayer

    2014-11-01

    Full Text Available Cognitive psychological research focusses on causal learning and reasoning while cognitive anthropological and social science research tend to focus on systems of beliefs. Our aim was to explore how these two types of research can inform each other. Cognitive psychological theories (causal model theory and causal Bayes nets were used to derive predictions for systems of causal beliefs. These predictions were then applied to lay theories of depression as a specific test case. A systematic literature review on causal beliefs about depression was conducted, including original, quantitative research. Thirty-six studies investigating 13 non-Western and 32 Western cultural groups were analysed by classifying assumed causes and preferred forms of treatment into common categories. Relations between beliefs and treatment preferences were assessed. Substantial agreement between cultural groups was found with respect to the impact of observable causes. Stress was generally rated as most important. Less agreement resulted for hidden, especially supernatural causes. Causal beliefs were clearly related to treatment preferences in Western groups, while evidence was mostly lacking for non-Western groups. Overall predictions were supported, but there were considerable methodological limitations. Pointers to future research, which may combine studies on causal beliefs with experimental paradigms on causal reasoning, are given.

  20. Causal beliefs about depression in different cultural groups—what do cognitive psychological theories of causal learning and reasoning predict?

    Science.gov (United States)

    Hagmayer, York; Engelmann, Neele

    2014-01-01

    Cognitive psychological research focuses on causal learning and reasoning while cognitive anthropological and social science research tend to focus on systems of beliefs. Our aim was to explore how these two types of research can inform each other. Cognitive psychological theories (causal model theory and causal Bayes nets) were used to derive predictions for systems of causal beliefs. These predictions were then applied to lay theories of depression as a specific test case. A systematic literature review on causal beliefs about depression was conducted, including original, quantitative research. Thirty-six studies investigating 13 non-Western and 32 Western cultural groups were analyzed by classifying assumed causes and preferred forms of treatment into common categories. Relations between beliefs and treatment preferences were assessed. Substantial agreement between cultural groups was found with respect to the impact of observable causes. Stress was generally rated as most important. Less agreement resulted for hidden, especially supernatural causes. Causal beliefs were clearly related to treatment preferences in Western groups, while evidence was mostly lacking for non-Western groups. Overall predictions were supported, but there were considerable methodological limitations. Pointers to future research, which may combine studies on causal beliefs with experimental paradigms on causal reasoning, are given. PMID:25505432

  1. Causal beliefs about depression in different cultural groups-what do cognitive psychological theories of causal learning and reasoning predict?

    Science.gov (United States)

    Hagmayer, York; Engelmann, Neele

    2014-01-01

    Cognitive psychological research focuses on causal learning and reasoning while cognitive anthropological and social science research tend to focus on systems of beliefs. Our aim was to explore how these two types of research can inform each other. Cognitive psychological theories (causal model theory and causal Bayes nets) were used to derive predictions for systems of causal beliefs. These predictions were then applied to lay theories of depression as a specific test case. A systematic literature review on causal beliefs about depression was conducted, including original, quantitative research. Thirty-six studies investigating 13 non-Western and 32 Western cultural groups were analyzed by classifying assumed causes and preferred forms of treatment into common categories. Relations between beliefs and treatment preferences were assessed. Substantial agreement between cultural groups was found with respect to the impact of observable causes. Stress was generally rated as most important. Less agreement resulted for hidden, especially supernatural causes. Causal beliefs were clearly related to treatment preferences in Western groups, while evidence was mostly lacking for non-Western groups. Overall predictions were supported, but there were considerable methodological limitations. Pointers to future research, which may combine studies on causal beliefs with experimental paradigms on causal reasoning, are given.

  2. Predicting Causal Relationships from Biological Data: Applying Automated Causal Discovery on Mass Cytometry Data of Human Immune Cells

    KAUST Repository

    Triantafillou, Sofia

    2017-09-29

    Learning the causal relationships that define a molecular system allows us to predict how the system will respond to different interventions. Distinguishing causality from mere association typically requires randomized experiments. Methods for automated  causal discovery from limited experiments exist, but have so far rarely been tested in systems biology applications. In this work, we apply state-of-the art causal discovery methods on a large collection of public mass cytometry data sets, measuring intra-cellular signaling proteins of the human immune system and their response to several perturbations. We show how different experimental conditions can be used to facilitate causal discovery, and apply two fundamental methods that produce context-specific causal predictions. Causal predictions were reproducible across independent data sets from two different studies, but often disagree with the KEGG pathway databases. Within this context, we discuss the caveats we need to overcome for automated causal discovery to become a part of the routine data analysis in systems biology.

  3. Agent Building Software

    Science.gov (United States)

    2000-01-01

    AgentBuilder is a software component developed under an SBIR contract between Reticular Systems, Inc., and Goddard Space Flight Center. AgentBuilder allows software developers without experience in intelligent agent technologies to easily build software applications using intelligent agents. Agents are components of software that will perform tasks automatically, with no intervention or command from a user. AgentBuilder reduces the time and cost of developing agent systems and provides a simple mechanism for implementing high-performance agent systems.

  4. K-causal structure of space-time in general relativity

    Indian Academy of Sciences (India)

    Abstract. Using K-causal relation introduced by Sorkin and Woolgar [1], we generalize results of Garcia-Parrado and Senovilla [2,3] on causal maps. We also introduce causality conditions with respect to K-causality which are analogous to those in classical causality theory and prove their inter-relationships. We introduce a ...

  5. Processing of Positive-Causal and Negative-Causal Coherence Relations in Primary School Children and Adults: A Test of the Cumulative Cognitive Complexity Approach in German

    Science.gov (United States)

    Knoepke, Julia; Richter, Tobias; Isberner, Maj-Britt; Naumann, Johannes; Neeb, Yvonne; Weinert, Sabine

    2017-01-01

    Establishing local coherence relations is central to text comprehension. Positive-causal coherence relations link a cause and its consequence, whereas negative-causal coherence relations add a contrastive meaning (negation) to the causal link. According to the cumulative cognitive complexity approach, negative-causal coherence relations are…

  6. Causal Learning in Gambling Disorder: Beyond the Illusion of Control.

    Science.gov (United States)

    Perales, José C; Navas, Juan F; Ruiz de Lara, Cristian M; Maldonado, Antonio; Catena, Andrés

    2017-06-01

    Causal learning is the ability to progressively incorporate raw information about dependencies between events, or between one's behavior and its outcomes, into beliefs of the causal structure of the world. In spite of the fact that some cognitive biases in gambling disorder can be described as alterations of causal learning involving gambling-relevant cues, behaviors, and outcomes, general causal learning mechanisms in gamblers have not been systematically investigated. In the present study, we compared gambling disorder patients against controls in an instrumental causal learning task. Evidence of illusion of control, namely, overestimation of the relationship between one's behavior and an uncorrelated outcome, showed up only in gamblers with strong current symptoms. Interestingly, this effect was part of a more complex pattern, in which gambling disorder patients manifested a poorer ability to discriminate between null and positive contingencies. Additionally, anomalies were related to gambling severity and current gambling disorder symptoms. Gambling-related biases, as measured by a standard psychometric tool, correlated with performance in the causal learning task, but not in the expected direction. Indeed, performance of gamblers with stronger biases tended to resemble the one of controls, which could imply that anomalies of causal learning processes play a role in gambling disorder, but do not seem to underlie gambling-specific biases, at least in a simple, direct way.

  7. [Causality link in criminal law: role of epidemiology].

    Science.gov (United States)

    Zocchetti, C; Riboldi, L

    2003-01-01

    This paper focusses on the role of epidemiology in demonstrating causality in criminal trials of toxic tort litigation. First of all, consideration is given of the specificity of the criminal trial and of the role of the epidemiologist as expert witness. As a second step the concept of causality is examined separating general from specific (individual level) causality. As regards general causality, strategies based on some criteria (example: Bradford-Hill criteria) are contrasted with approaches that do not consider causality a matter of science but one of health policy; and specific methods frequently used (meta-analysis, risk assessment, International Boards evaluation,....) are discussed, with special reference to the adoption of high-level standards and to the context of cross-examination. As regards individual level causality the difficulties of the epidemiologic approach to such evaluation are stressed, with special reference to topics like expected value, attributable risk, and probability of causation. All examples are taken from Italian court trials. A general comment on the difficulties of using the criminal trial (dominated by the "but for" rule) for toxic tort litigation and on the opportunity to switch to trials (civil, administrative) with less stringent causal rules ("more probable than not") is offered, with a consideration also of what are called "class actions".

  8. Cortical hierarchies perform Bayesian causal inference in multisensory perception.

    Science.gov (United States)

    Rohe, Tim; Noppeney, Uta

    2015-02-01

    To form a veridical percept of the environment, the brain needs to integrate sensory signals from a common source but segregate those from independent sources. Thus, perception inherently relies on solving the "causal inference problem." Behaviorally, humans solve this problem optimally as predicted by Bayesian Causal Inference; yet, the underlying neural mechanisms are unexplored. Combining psychophysics, Bayesian modeling, functional magnetic resonance imaging (fMRI), and multivariate decoding in an audiovisual spatial localization task, we demonstrate that Bayesian Causal Inference is performed by a hierarchy of multisensory processes in the human brain. At the bottom of the hierarchy, in auditory and visual areas, location is represented on the basis that the two signals are generated by independent sources (= segregation). At the next stage, in posterior intraparietal sulcus, location is estimated under the assumption that the two signals are from a common source (= forced fusion). Only at the top of the hierarchy, in anterior intraparietal sulcus, the uncertainty about the causal structure of the world is taken into account and sensory signals are combined as predicted by Bayesian Causal Inference. Characterizing the computational operations of signal interactions reveals the hierarchical nature of multisensory perception in human neocortex. It unravels how the brain accomplishes Bayesian Causal Inference, a statistical computation fundamental for perception and cognition. Our results demonstrate how the brain combines information in the face of uncertainty about the underlying causal structure of the world.

  9. Spacetime Causal Structure and Dimension from Horismotic Relation

    Directory of Open Access Journals (Sweden)

    O. C. Stoica

    2016-01-01

    Full Text Available A reflexive relation on a set can be a starting point in defining the causal structure of a spacetime in General Relativity and other relativistic theories of gravity. If we identify this relation as the relation between lightlike separated events (the horismos relation, we can construct in a natural way the entire causal structure: causal and chronological relations, causal curves, and a topology. By imposing a simple additional condition, the structure gains a definite number of dimensions. This construction works with both continuous and discrete spacetimes. The dimensionality is obtained also in the discrete case, so this approach can be suited to prove the fundamental conjecture of causal sets. Other simple conditions lead to a differentiable manifold with a conformal structure (the metric up to a scaling factor as in Lorentzian manifolds. This structure provides a simple and general reconstruction of the spacetime in relativistic theories of gravity, which normally requires topological structure, differential structure, and geometric structure (which decomposes in the conformal structure, giving the causal relations and the volume element. Motivations for such a reconstruction come from relativistic theories of gravity, where the conformal structure is important, from the problem of singularities, and from Quantum Gravity, where various discretization methods are pursued, particularly in the causal sets approach.

  10. Causalidade e epidemiologia Causality and epidemiology

    Directory of Open Access Journals (Sweden)

    Rita Barradas Barata

    1997-06-01

    Full Text Available Este texto trata da questão da causalidade em epidemiologia. Começa com um breve retrospecto histórico para recuperar os diversos sentidos dados ao conceito pelos principais filósofos ocidentais. Em seguida, considera as raízes históricas da epidemiologia enquanto disciplina científica e as transformações que o conceito de causa sofreu em seu âmbito. Estabelecidas essas premissas, analisa-se o desenvolvimento da epidemiologia no século XX e a crise de paradigma que enfrenta na atualidade. Como saídas para a crise, no que se refere à questão da causalidade, examina três alternativas: a epidemiologia social, a crítica popperiana a os aportes da biologia molecular. Finalmente, comenta a necessiclade de uma nova teoria epidemiológica construída a partir da teoria da complexidade.In examining the issue of causality whithin epidemiology, the text begins with a brief historical overview that reclaims the different meanings which the West's main philosophers have lent to this concept. It next delves into the historical roots of epidemiology as a scientific discipline and the transformations the concept of cause has undergone to within this realm. With these presuppositions in place, the text goes on to analyse the 20th century development of epidemiology and the crisis ít currently faces in terms of paradigm. Three alternatives are explored as ways out of this crisis: social epidemiology, Popperian criticism and the contributions of molecular biology. Lastly, the tent discusses the need for a new epidemiological theory grounded on the theory of complexity.

  11. Radicinin from Cochliobolus sp. inhibits Xylella fastidiosa, the causal agent of Pierce's Disease of grapevine.

    Science.gov (United States)

    Aldrich, Thomas J; Rolshausen, Philippe E; Roper, M Caroline; Reader, Jordan M; Steinhaus, Matthew J; Rapicavoli, Jeannette; Vosburg, David A; Maloney, Katherine N

    2015-08-01

    The fastidious phytopathogenic bacterium, Xylella fastidiosa, poses a substantial threat to many economically important crops, causing devastating diseases including Pierce's Disease of grapevine. Grapevines (Vitis vinifera L.) planted in an area under Pierce's Disease pressure often display differences in disease severity and symptom expression, with apparently healthy vines growing alongside the dying ones, despite the fact that all the vines are genetic clones of one another. Under the hypothesis that endophytic microbes might be responsible for this non-genetic resistance to X. fastidiosa, endophytic fungi were isolated from vineyard cvs. 'Chardonnay' and 'Cabernet Sauvignon' grown under high Pierce's Disease pressure. A Cochliobolus sp. isolated from a Cabernet Sauvignon grapevine inhibited the growth of X. fastidiosa in vitro. Bioassay-guided isolation of an organic extract of Cochliobolus sp. yielded the natural product radicinin as the major active compound. Radicinin also inhibited proteases isolated from the culture supernatant of X. fastidiosa. In order to assess structure-activity relationships, three semi-synthetic derivatives of radicinin were prepared and tested for activity against X. fastidiosa in vitro. Assay results of these derivatives are consistent with enzyme inactivation by conjugate addition to carbon-10 of radicinin, as proposed previously. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Identification of Agrobacterium vitis as a causal agent of grapevine crown gall in Serbia

    Directory of Open Access Journals (Sweden)

    Kuzmanović N.

    2012-01-01

    Full Text Available In 2010, a serious outbreak of crown gall disease was observed on grapevines (Vitis vinifera L. cv. Cabernet Sauvignon in several commercial vineyards located in the Vojvodina province, Serbia. Bacteria were isolated from the young tumor tissue on nonselective YMA medium and five representative strains were selected for further identification. Tumorigenic (Ti plasmid was detected in all strains by PCR using primers designed to amplify the virC pathogenicity gene, producing a 414-bp PCR product. The strains were identified as Agrobacterium vitis using differential physiological and biochemical tests, and a multiplex PCR assay targeting 23S rRNA gene sequences. In the pathogenicity assay, all strains induced characteristic symptoms on inoculated tomato and grapevine plants. They were less virulent on tomato plants in comparison to the reference strains of A. tumefaciens and A. vitis. [Ministarstva nauke Republike Srbije, br. III46008: Development of integrated management of harmful organisms in plant production in order to overcome resistance and to improve food quality and safety

  13. The United States Civil War Causal Agent for Irish Assimilation and Acceptance in US Society

    National Research Council Canada - National Science Library

    Gillespie, William

    2001-01-01

    The American Civil War was a cornerstone event for the Irish in America. Their participation proved their duty to Union and Confederate causes, increased their acceptance in American society, and hastened assimilation...

  14. IDENTIFICACIÓN DEL AGENTE CAUSAL DE LA ANTRACNOSIS DE Sansevieria spp. EN COSTA RICA

    Directory of Open Access Journals (Sweden)

    Gerardo Pérez-León

    2013-01-01

    Full Text Available Sansevieria spp. (Agavaceae es una ornamental de follaje originaria de África y Asia. S. trifasciata (St es la especie con mayor número de cultivares en el mercado de exportación de Costa Rica a Estados Unidos y Holanda. Muestras foliares de S. trifasciata var. “Hahnii” con lesiones circulares y acuosas (algunas alargadas y secas, fueron analizadas. El patógeno recuperado fue identificado como Colletotrichum sansevieriae Nakamura (CsN mediante pruebas de patogenicidad, morfología y técnicas moleculares. Los aislamientos mono-hifales presentaron coloración crema, crecimiento postrado y escasa producción de conidios. La patogenicidad de CsN se evaluó en 7 variedades de St; Sansevieriasp., var., jiboia; S. cylindrica y las ornamentalesCodiaeum variegatum, Cordelyne terminalis y Dracaena deremensis, mediante 2 sistemas deinoculación: plantas en maceta (invernaderoy hojas separadas (laboratorio; con ambos sereprodujeron los síntomas de la enfermedad. Cinco de las variedades de S. trifasciata desarrollaron síntomas, “Hahnii” la más susceptible. Ninguna de las otras ornamentales presentósíntomas. CsN fue re-aislado de hojas inoculadas (postulados de Koch. La amplificación mediante PCR de la región ITS con los iniciadores ITS5 e ITS4 produjo un fragmento de aproximadamente 600pb, cuya secuencia de nucleótidos fue idéntica para los aislamientos mono-hifales. En el Banco de Genes, la secuencia alineó con accesiones de CsN de Australia y USA, con un índice de simi laridad del 99 al 100%. El análisis filogenético, con base en la región ITS2, agrupó (99% valor debootstrap los aislamientos costarricenses con elaislamiento tipo CsN de Japón y los de Australia y USA. Hasta donde se conoce, éste es el primer informe de la antracnosis de Sansevieria en C. R.

  15. Consideraciones sobre Botrytis cinerea pers., agente causal de la pudrición de las flores

    Directory of Open Access Journals (Sweden)

    Garcés de Granada Emira

    1992-12-01

    Full Text Available El "moho gris" de las flores, ocasionado por el hongo
    Botrytis cinerea Pers., es una enfermedad de la cual
    se desconocen muchos aspectos fundamentales. Sin embargo y a pesar de esta carencia de conocimientos, frecuentemente se aplican fungicidas que, muchas veces, no resultan efectivos para el control adecuado de la enfermedad e, incluso, se exagera en uso, lo cual significa un aumento de costos y un efecto en el ambiente. Esta enfermedad es muy común en muchas flores de exportación, como rosa, clavel, crisantemo, estatice y gypsophila. Staby y Naegele (1985 opinan que las plantas pueden ser atacadas en el campo, en el transporte o en el almacenamiento. La penetración del patógeno se realiza directamente a través de heridas causadas por insectos o por medios mecánicos. En condiciones muy favorables, el hongo puede penetrar
    directamente en sus hospedantes a través de la cutícula, mediante la producción de enzimas que degradan los componentes de ésta.

  16. Genetic diversity and population differentiation of the causal agent of citrus black spot in Brazil.

    Science.gov (United States)

    Wickert, Ester; de Goes, Antonio; de Souza, Andressa; Lemos, Eliana Gertrudes de Macedo

    2012-01-01

    One of the most important diseases that affect sweet orange orchards in Brazil is the Citrus Black Spot that is caused by the fungus Guignardia citricarpa. This disease causes irreparable losses due to the premature falling of fruit, as well as its severe effects on the epidermis of ripe fruit that renders them unacceptable at the fresh fruit markets. Despite the fact that the fungus and the disease are well studied, little is known about the genetic diversity and the structure of the fungi populations in Brazilian orchards. The objective of this work was study the genetic diversity and population differentiation of G. citricarpa associated with four sweet orange varieties in two geographic locations using DNA sequence of ITS1-5.8S-ITS2 region from fungi isolates. We observed that different populations are closely related and present little genetic structure according to varieties and geographic places with the highest genetic diversity distributed among isolates of the same populations. The same haplotypes were sampled in different populations from the same and different orange varieties and from similar and different origins. If new and pathogenic fungi would become resistant to fungicides, the observed genetic structure could rapidly spread this new form from one population to others.

  17. Genetic Diversity and Population Differentiation of the Causal Agent of Citrus Black Spot in Brazil

    OpenAIRE

    Ester Wickert; Antonio de Goes; Andressa de Souza; Eliana Gertrudes de Macedo Lemos

    2012-01-01

    One of the most important diseases that affect sweet orange orchards in Brazil is the Citrus Black Spot that is caused by the fungus Guignardia citricarpa. This disease causes irreparable losses due to the premature falling of fruit, as well as its severe effects on the epidermis of ripe fruit that renders them unacceptable at the fresh fruit markets. Despite the fact that the fungus and the disease are well studied, little is known about the genetic diversity and the structure of the fungi p...

  18. Diversity and biological control of Sclerotium rolfsii, causal agent of stem rot of groundnut

    NARCIS (Netherlands)

    Lê, N.C.

    2011-01-01

    Groundnut (Arachis hypogaea L.) is an economically important legume crop in Vietnam and many other countries worldwide. Stem rot disease, caused by the soil-borne fungus Sclerotium rolfsii Sacc., is a major yield limiting factor in groundnut cultivation. Current control methods

  19. Integrated Management of Causal Agents of Postharvest Fruit Rot of Apple

    OpenAIRE

    Mila Grahovac; Dušanka Inđić; Brankica Tanović; Sanja Lazić; Slavica Vuković; Jovana Hrustić; Sonja Gvozdenac

    2011-01-01

    One of the major causes of poor quality and fruit loss (during storage and transport) are diseases caused by phytopathogenic fungi. Economic losses which are the consequence of the phytopathogenic fungus activity after harvest exceed the losses in the field. The most important postharvest fungal pathogens of apple fruits are: Botrytis cinerea Pers. ex Fr., Penicillium expansum (Lk.) Thom., Cryptosporiopsis curvispora (Peck.) Grem., Colletotrichum gloeospori...

  20. De novo genome assembly of Geosmithia morbida, the causal agent of thousand cankers disease

    Directory of Open Access Journals (Sweden)

    Taruna A. Schuelke

    2016-05-01

    Full Text Available Geosmithia morbida is a filamentous ascomycete that causes thousand cankers disease in the eastern black walnut tree. This pathogen is commonly found in the western U.S.; however, recently the disease was also detected in several eastern states where the black walnut lumber industry is concentrated. G. morbida is one of two known phytopathogens within the genus Geosmithia, and it is vectored into the host tree via the walnut twig beetle. We present the first de novo draft genome of G. morbida. It is 26.5 Mbp in length and contains less than 1% repetitive elements. The genome possesses an estimated 6,273 genes, 277 of which are predicted to encode proteins with unknown functions. Approximately 31.5% of the proteins in G. morbida are homologous to proteins involved in pathogenicity, and 5.6% of the proteins contain signal peptides that indicate these proteins are secreted. Several studies have investigated the evolution of pathogenicity in pathogens of agricultural crops; forest fungal pathogens are often neglected because research efforts are focused on food crops. G. morbida is one of the few tree phytopathogens to be sequenced, assembled and annotated. The first draft genome of G. morbida serves as a valuable tool for comprehending the underlying molecular and evolutionary mechanisms behind pathogenesis within the Geosmithia genus.

  1. Draft Genome Sequence of the Phytopathogenic Fungus Fusarium euwallaceae, the Causal Agent of Fusarium Dieback.

    Science.gov (United States)

    Ibarra-Laclette, Enrique; Sánchez-Rangel, Diana; Hernández-Domínguez, Eric; Pérez-Torres, Claudia-Anahí; Ortiz-Castro, Randy; Villafán, Emanuel; Alonso-Sánchez, Alexandro; Rodríguez-Haas, Benjamín; López-Buenfil, Abel; García-Avila, Clemente; Ramírez-Pool, José-Abrahán

    2017-08-31

    Here, we report the genome of Fusarium euwallaceae strain HFEW-16-IV-019, an isolate obtained from Kuroshio shot hole borer (a Euwallacea sp.). These beetles were collected in Tijuana, Mexico, from elm trees showing typical symptoms of Fusarium dieback. The final assembly consists of 287 scaffolds spanning 48,274,071 bp and 13,777 genes. Copyright © 2017 Ibarra-Laclette et al.

  2. Fungicide baseline for mycelial sensitivity of Exserohilum turcicum, causal agent of northern corn leaf blight

    Directory of Open Access Journals (Sweden)

    Roberto Luis De Rossi

    2015-03-01

    Full Text Available Northern corn leaf blight, caused by Exserohilum turcicum (Et, is one of the major corn diseases which can reduce grain yield and quality. The aim of this study was to determine the mycelial sensitivity of ten Et isolates, five from Argentina and five from Brazil, to six fungicides (carbendazim, captan, fludioxinil, metalaxyl, iprodione and thiram used in seed treatment. The inhibitory concentration (IC50 was determined by using seven concentrations of the fungicides supplemented to the agar medium. The mycelial colony diameter was measured with a digital caliper. Experimental design was completely randomized with four replicates. Data on the percent mycelial growth inhibition were analyzed by logarithmic regression and the IC50 was calculated. The fungicide iprodione was the most potent, with IC50 50 mg/L for all isolates. Although iprodione is the most potent fungicide, it is not used for corn seed treatment. The IC50s obtained in this study can be used as baseline for future monitoring studies of Et sensitivity to fungicides.

  3. Genetic Diversity and Population Differentiation of the Causal Agent of Citrus Black Spot in Brazil

    Directory of Open Access Journals (Sweden)

    Ester Wickert

    2012-01-01

    Full Text Available One of the most important diseases that affect sweet orange orchards in Brazil is the Citrus Black Spot that is caused by the fungus Guignardia citricarpa. This disease causes irreparable losses due to the premature falling of fruit, as well as its severe effects on the epidermis of ripe fruit that renders them unacceptable at the fresh fruit markets. Despite the fact that the fungus and the disease are well studied, little is known about the genetic diversity and the structure of the fungi populations in Brazilian orchards. The objective of this work was study the genetic diversity and population differentiation of G. citricarpa associated with four sweet orange varieties in two geographic locations using DNA sequence of ITS1-5.8S-ITS2 region from fungi isolates. We observed that different populations are closely related and present little genetic structure according to varieties and geographic places with the highest genetic diversity distributed among isolates of the same populations. The same haplotypes were sampled in different populations from the same and different orange varieties and from similar and different origins. If new and pathogenic fungi would become resistant to fungicides, the observed genetic structure could rapidly spread this new form from one population to others.

  4. Evidence for sexual reproduction in Venturia effusa, causal agent of pecan scab

    Science.gov (United States)

    Pecan scab caused by Venturia effusa is widespread across southwest USA and epidemics can result in catastrophic yield loss. Venturia effusa reproduces asexually during the active phase of the disease cycle (spring through summer) with no evidence of a sexual cycle. Yet, genetic diversity among popu...

  5. Cucumber mosaic virus associated RNA 5: causal agent for tomato necrosis.

    Science.gov (United States)

    Kaper, J M; Waterworth, H E

    1977-04-22

    A small replicating RNA, encapsidated with and dependent on, but not part of the viral genome, modifies disease expression depending on the host. In tomato plants, it causes a lethal necrotic disease which is probably the same as that which, in 1972, destroyed most of the field tomato crop in large regions of the French Alsace.

  6. Phytotoxins produced by Pestalotiopsis guepinii, the causal agent of hazelnut twig blight

    Directory of Open Access Journals (Sweden)

    Muharrem TÜRKKAN

    2011-05-01

    Full Text Available Normal 0 14 false false false IT ZH-TW X-NONE MicrosoftInternetExplorer4 The main lipophilic phytotoxic metabolite was isolated from the culture filtrates of Pestalotiopsis guepinii, the fungus causing twig blight of hazelnut. The metabolite was spectroscopically identified as pestalopyrone, a pentaketide that it was originally identified as a minor toxin produced by Pestalotiopsis oenotherae. The toxic activity of pestalopyrone was compared with that of nectriapyrone, a structurally related monoterpenoid recently isolated from Phomopsis foeniculi, and that of the new dihydro-derivative of nectriapyrone. The high phytotoxic activity of nectriapyrone and its dihydro-derivative on three non host  plants, showed that the double bond of the 1-methylpropenyl group at C-6 of the aromatic ring is inessential for its activity, while the much lower activity of pestalopyrone showed that the methyl group at C-3 of the same ring is an important structural feature. The high molecular weight hydrophilic phytotoxins produced by this fungus are reported for the first time.

  7. Use of experimental translocations of Allegheny woodrat to decipher causal agents of decline.

    Science.gov (United States)

    Smyser, Timothy J; Johnson, Scott A; Page, L Kristen; Hudson, Cassie M; Rhodes, Olin E

    2013-08-01

    Translocations are an important tool for wildlife conservation, although progress in the field of reintroduction biology has been hindered by the ad hoc and opportunistic nature of many translocations. We used an experimental translocation to elucidate the role of raccoon roundworm (Baylisascaris procyonis) and inbreeding depression in the decline of the Allegheny woodrat (Neotoma magister), an endangered species. We translocated woodrats from genetically diverse populations in the core of the species range to 4 previously occupied sites (reintroductions) and 2 sites supporting genetically depauperate populations (reinforcements) in Indiana (U.S.A.). In 2 reintroduction sites and 1 reinforcement site, we distributed anthelmintic baits to passively deworm raccoons and reduce the risk of woodrat exposure to roundworms. The remaining sites served as controls. We used raccoon latrine surveys and fecal flotation to monitor temporal variability in roundworm prevalence and effect of treatment. We used live trapping and microsatellite genotyping to monitor the demographic and genetic response of translocated populations over the following 54 months. At the conclusion of the study, 4 of 6 translocations were successfully maintaining abundance through local recruitment. The distribution of anthelmintic baits reduced levels of roundworm contamination, but levels of contamination were also low in 2 of 3 control sites. Reintroductions failed at control sites, one of which was due to high roundworm exposure. The other failed control reintroduction was likely attributable to demographic stochasticity and limited reproductive potential following initial mortality within the first 4 months. In both control and treatment reinforcements, increases in both allelic richness and heterozygosity were accompanied by increases in abundance, which is suggestive of genetic rescue. Our results demonstrate that mitigation of roundworm exposure through the distribution of anthelmintic baits can facilitate woodrat recovery and that diversity within genetically depauperate populations can be restored through the introduction of a limited number of individuals. © 2013 Society for Conservation Biology.

  8. Draft genome sequence of XANTHOMONAS ARBORICOLA strain 3004, causal agent of bacterial disease on barley

    Science.gov (United States)

    We report here the annotated genome sequence of XANTHOMONAS ARBORICOLA str. 3004, a Gram-negative phytopathogenic bacteria that includes several pathovars characterized by virulence specificity. Strain 3004 was isolated from barley leaves with symptoms of streak (bacterial blight) and also can infec...

  9. Interaction of Aceria mangiferae with Fusarium mangiferae, the causal agent of mango malformation disease

    Science.gov (United States)

    The study examines the role of the mango bud mite, Aceria mangiferae, in carrying Fusarium mangiferae’s conidia, vectoring them into the penetration sites and assisting fungal penetration and dissemination. Conidia that were exposed to a green fluorescent protein (gfp)-marked isolate of F. mangifer...

  10. Lecanicillium fungicola: causal agent of dry dubble disease in white-button mushroom

    NARCIS (Netherlands)

    Berendsen, R.L.; Baars, J.J.P.; Kalkhove, S.I.; Lugones, L.G.; Wösten, H.A.B.; Bakker, P.A.H.M.

    2010-01-01

    Lecanicillium fungicola causes dry bubble disease in commercially cultivated mushroom. This review summarizes current knowledge on the biology of the pathogen and the interaction between the pathogen and its most important host, the white-button mushroom, Agaricus bisporus. The ecology of the

  11. Pectobacterium carotovorum subsp. carotovorum – the causal agent of broccoli soft rot in Serbia

    Directory of Open Access Journals (Sweden)

    Katarina Gašić

    2014-12-01

    Full Text Available Soft rot symptoms were observed on broccoli plants in several commercial fields in the western part of Serbia. Six strains of bacteria were isolated from diseased tissues and identified as Pectobacterium carotovorum subsp. carotovorum using conventional bacteriological and molecular methods. All strains were non-fluorescent, gram-negative, facultative anaerobes, oxidase-negative and catalase-positive, causing soft rot on potato and carrot slices and did not induce hypersensitive reaction on tobacco leaves. They grew in 5% NaCl and at 37°C, did not produce acid from α-methyl glucoside, sorbitol and maltose, nor reducing substances from sucrose, but utilized lactose and trehalose, and did not produce indole or lecithinase. The investigated strains showed characteristic growth on Logan’s medium and did not produce blue pigmented indigoidine on GYCA medium nor “fried egg” colonies on PDA. The identity of strains was confirmed by ITS-PCR and ITS-RFLP analyses and by sequence analysis of the 16S rRNA gene. In a pathogenicity assay, all strains caused tissue discoloration and soft rot development on inoculated broccoli head tissue fragments.

  12. Pectobacterium carotovorum subsp. carotovorum – the Causal Agent of Calla Soft Rot in Serbia and Montenegro

    Directory of Open Access Journals (Sweden)

    Milan Ivanović

    2009-01-01

    Full Text Available Bacterial strains were isolated from above- and underground parts of diseased calla plants originating from different localities in Serbia and one locality in Montenegro. They were characterized by studying their pathogenic, cultural, biochemical and physiologicalcharacteristics. All investigated strains caused soft rot of calla leaf stalks, potato slices and aloe leaves, and induced hypersensitive reaction on tobacco. Bacteriological properties of the strains indicated that symptoms on calla plants were caused by Gram-negative, nonfluorescent, oxidase negative, catalase positive and facultatively anaerobic bacterium belonging to the genus Pectobacterium. The investigated strains grew at 37ºC and in 5% NaCl, utilised lactose and trechalose, and produced neither indol nor lecitinase. These results, as well as the characteristic growth on Logan’s differential medium indicated that soft rot of tuber and stem base of calla plants was caused by Pectobacterium carotovorum subsp. carotovorum. This is the first report of this pathogen affecting calla plants in Serbia.

  13. De novo genome assembly of Geosmithia morbida, the causal agent of thousand cankers disease

    Science.gov (United States)

    Taruna A. Schuelke; Anthony Westbrook; Kirk Broders; Keith Woeste; Matthew D. MacManes

    2016-01-01

    Geosmithia morbida is a filamentous ascomycete that causes thousand cankers disease in the eastern black walnut tree. This pathogen is commonly found in the western U.S.; however, recently the disease was also detected in several eastern states where the black walnut lumber industry is concentrated. G. morbida is one of two...

  14. Detection and characterization of mango malformation and its causal agent in Spain

    OpenAIRE

    Crespo Palomo, María

    2014-01-01

    El mango (Mangifera indica L.) es un árbol originario de la región indobirmana, laderas del Himalaya y Sri Lanka, donde aún existen poblaciones silvestres y ha sido cultivado desde la antigüedad en la India como atestiguan las sagradas escrituras hindúes, los libros de los Vedas, redactadas entre el 1500 y el 1000 a. C. (Galán-Saúco, 2009). La dispersión del mango fue muy rápida por el subcontinente de la India y el archipiélago malayo con la apertura del comercio entre Asia y Europa. El mang...

  15. Fusarium proliferatum - Causal agent of garlic bulb rot in Spain: Genetic variability and mycotoxin production.

    Science.gov (United States)

    Gálvez, Laura; Urbaniak, Monika; Waśkiewicz, Agnieszka; Stępień, Łukasz; Palmero, Daniel

    2017-10-01

    Fusarium proliferatum is a world-wide occurring fungal pathogen affecting several crops included garlic bulbs. In Spain, this is the most frequent pathogenic fungus associated with garlic rot during storage. Moreover, F. proliferatum is an important mycotoxigenic species, producing a broad range of toxins, which may pose a risk for food safety. The aim of this study is to assess the intraspecific variability of the garlic pathogen in Spain implied by analyses of translation elongation factor (tef-1α) and FUM1 gene sequences as well as the differences in growth rates. Phylogenetic characterization has been complemented with the characterization of mating type alleles as well as the species potential as a toxin producer. Phylogenetic trees based on the sequence of the translation elongation factor and FUM1 genes from seventy nine isolates from garlic revealed a considerable intraspecific variability as well as high level of diversity in growth speed. Based on the MAT alleles amplified by PCR, F. proliferatum isolates were separated into different groups on both trees. All isolates collected from garlic in Spain proved to be fumonisin B 1 , B 2 , and B 3 producers. Quantitative analyses of fumonisins, beauvericin and moniliformin (common secondary metabolites of F. proliferatum) showed no correlation with phylogenetic analysis neither mycelial growth. This pathogen presents a high intraspecific variability within the same geographical region and host, which is necessary to be considered in the management of the disease. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Genetic Diversity of Xanthomonas campestris pv. vitians, the Causal Agent of Bacterial Leafspot of Lettuce.

    Science.gov (United States)

    Barak, Jeri D; Gilbertson, Robert L

    2003-05-01

    ABSTRACT Bacterial leafspot of lettuce (BLS), caused by Xanthomonas campes-tris pv. vitians, has become more prevalent in many lettuce-growing areas of the world over the past decade. To gain insight into the nature of these outbreaks, the genetic variation in X. campestris pv. vitians strains from different geographical locations was examined. All strains were first tested for pathogenicity on lettuce plants, and then genetic diversity was assessed using (i) gas-chromatographic analysis of bacterial fatty acids, (ii) polymerase chain reaction analysis of repetitive DNA sequences (rep-PCR), (iii) DNA sequence analysis of the internal transcribed spacer region 1 (ITS1) of the ribosomal RNA, (iv) restriction fragment length polymorphism (RFLP) analysis of total genomic DNA with a repetitive DNA probe, and (v) detection and partial characterization of plasmid DNA. Fatty acid analysis identified all pathogenic strains as X. campestris, but did not consistently identify all the strains as X. campestris pv. vitians. The rep-PCR fingerprints and ITS1 sequences of all pathogenic X. campestris pv. vitians strains examined were identical, and distinct from those of the other X. campestris pathovars. Thus, these characteristics did not reveal genetic diversity among X. campestris pv. vitians strains, but did allow for differentiation of X. campestris pathovars. Genetic diversity among X. campestris pv. vitians strains was revealed by RFLP analysis with a repetitive DNA probe and by characterization of plasmid DNA. This diversity was greatest among strains from different geographical regions, although diversity among strains from the same location also was detected. The results of this study suggest that these X. campestris pv. vitians strains are not clonal, but comprise a relatively homogeneous group.

  17. Imputation of adverse drug reactions: Causality assessment in hospitals.

    Science.gov (United States)

    Varallo, Fabiana Rossi; Planeta, Cleopatra S; Herdeiro, Maria Teresa; Mastroianni, Patricia de Carvalho

    2017-01-01

    Different algorithms have been developed to standardize the causality assessment of adverse drug reactions (ADR). Although most share common characteristics, the results of the causality assessment are variable depending on the algorithm used. Therefore, using 10 different algorithms, the study aimed to compare inter-rater and multi-rater agreement for ADR causality assessment and identify the most consistent to hospitals. Using ten causality algorithms, four judges independently assessed the first 44 cases of ADRs reported during the first year of implementation of a risk management service in a medium complexity hospital in the state of Sao Paulo (Brazil). Owing to variations in the terminology used for causality, the equivalent imputation terms were grouped into four categories: definite, probable, possible and unlikely. Inter-rater and multi-rater agreement analysis was performed by calculating the Cohen´s and Light´s kappa coefficients, respectively. None of the algorithms showed 100% reproducibility in the causal imputation. Fair inter-rater and multi-rater agreement was found. Emanuele (1984) and WHO-UMC (2010) algorithms showed a fair rate of agreement between the judges (k = 0.36). Although the ADR causality assessment algorithms were poorly reproducible, our data suggest that WHO-UMC algorithm is the most consistent for imputation in hospitals, since it allows evaluating the quality of the report. However, to improve the ability of assessing the causality using algorithms, it is necessary to include criteria for the evaluation of drug-related problems, which may be related to confounding variables that underestimate the causal association.

  18. Causality and prediction: differences and points of contact

    Directory of Open Access Journals (Sweden)

    Luis Carlos Silva Ayçaguer, PhD

    2014-09-01

    Full Text Available This contribution presents the differences between those variables that might play a causal role in a certain process and those only valuable for predicting the outcome. Some considerations are made about the core intervention of the association and the temporal precedence and biases in both cases, the study of causality and predictive modeling. In that context, several relevant aspects related to the design of the corresponding studies are briefly reviewed and some of the mistakes that are often committed in handling both, causality and prediction, are illustrated.

  19. Causality in thermoelectric systems: Insights from block diagrams

    Science.gov (United States)

    Apertet, Y.

    2016-12-01

    While Carnot's model engines demonstrate ideal performances regarding conversion efficiency, they cannot be actually used as energy converters since they are non-causal systems. Such an unphysical behavior indeed restrains the working conditions to a single point where, in the case of a refrigerator (generator), the cooling power (output power) vanishes. Focusing on the example of a thermoelectric refrigerator, we study the impact of different dissipation sources on the causality of such systems. Basing our analysis on the block diagram description of this system, we discuss particularly the fact that heat conduction cannot ensure causality.

  20. Causal influence in linear Langevin networks without feedback

    Science.gov (United States)

    Auconi, Andrea; Giansanti, Andrea; Klipp, Edda

    2017-04-01

    The intuition of causation is so fundamental that almost every research study in life sciences refers to this concept. However, a widely accepted formal definition of causal influence between observables is still missing. In the framework of linear Langevin networks without feedback (linear response models) we propose a measure of causal influence based on a new decomposition of information flows over time. We discuss its main properties and we compare it with other information measures like the transfer entropy. We are currently unable to extend the definition of causal influence to systems with a general feedback structure and nonlinearities.

  1. Two-dimensional Minkowski causal automorphisms and conformal maps

    Science.gov (United States)

    Burgos, Juan Manuel

    2013-02-01

    Treating the two-dimensional Minkowski space as a Wick rotated version of the complex plane, we characterize the causal automorphisms in the two-dimensional Minkowski space as the Märzke-Wheeler maps of a certain class of observers. We also characterize the differentiable causal automorphisms of this space as the Minkowski conformal maps whose restriction to the time axis belongs to the class of observers mentioned above. We answer a recently raised question about whether causal automorphisms are characterized by their wave equation. As another application of the theory, we give a proper time formula for accelerated observers which solves the twin paradox in two-dimensional Minkowski spacetime.

  2. Kernel canonical-correlation Granger causality for multiple time series.

    Science.gov (United States)

    Wu, Guorong; Duan, Xujun; Liao, Wei; Gao, Qing; Chen, Huafu

    2011-04-01

    Canonical-correlation analysis as a multivariate statistical technique has been applied to multivariate Granger causality analysis to infer information flow in complex systems. It shows unique appeal and great superiority over the traditional vector autoregressive method, due to the simplified procedure that detects causal interaction between multiple time series, and the avoidance of potential model estimation problems. However, it is limited to the linear case. Here, we extend the framework of canonical correlation to include the estimation of multivariate nonlinear Granger causality for drawing inference about directed interaction. Its feasibility and effectiveness are verified on simulated data. ©2011 American Physical Society

  3. Is Host-Based Anomaly Detection + Temporal Correlation = Worm Causality

    National Research Council Canada - National Science Library

    Sekar, Vyas; Xie, Yinglian; Reiter, Michael K; Zhang, Hui

    2007-01-01

    Epidemic-spreading attacks (e.g., worm and botnet propagation) have a natural notion of attack causality - a single network flow causes a victim host to get infected and subsequently spread the attack...

  4. On Storks and Babies: Correlation, Causality and Field Experiments

    Directory of Open Access Journals (Sweden)

    Lambrecht Anja

    2016-11-01

    Full Text Available The explosion of available data has created much excitement among marketing practitioners about their ability to better understand the impact of marketing investments. Big data allows for detecting patterns and often it seems plausible to interpret them as causal. While it is quite obvious that storks do not bring babies, marketing relationships are usually less clear. Apparent “causalities” often fail to hold up under examination. If marketers want to be sure not to walk into a causality trap, they need to conduct field experiments to detect true causal relationships. In the present digital environment, experiments are easier than ever to execute. However, they need to be prepared and interpreted with great care in order to deliver meaningful and genuinely causal results that help improve marketing decisions.

  5. The Central Dogma as a thesis of causal specificity.

    Science.gov (United States)

    Weber, Marcel

    2006-01-01

    I present a reconstruction of F.H.C. Crick's two 1957 hypotheses 'Sequence Hypothesis' and 'Central Dogma' in terms of a contemporary philosophical theory of causation. Analyzing in particular the experimental evidence that Crick cited, I argue that these hypotheses can be understood as claims about the actual difference-making cause in protein synthesis. As these hypotheses are only true if restricted to certain nucleic acids in certain organisms, I then examine the concept of causal specificity and its potential to counter claims about causal parity of DNA and other cellular components. I first show that causal specificity is a special kind of invariance under interventions, namely invariance of generalizations that range over finite sets of discrete variables. Then, I show that this notion allows the articulation of a middle ground in the debate over causal parity.

  6. "Head take you": causal attributions of mental illness in Jamaica.

    Science.gov (United States)

    Arthur, Carlotta M; Whitley, Rob

    2015-02-01

    Causal attributions are a key factor in explanatory models of illness; however, little research on causal attributions of mental illness has been conducted in developing nations in the Caribbean, including Jamaica. Explanatory models of mental illness may be important in understanding illness experience and be a crucial factor in mental health service seeking and utilization. We explored causal attributions of mental illness in Jamaica by conducting 20 focus groups, including 16 community samples, 2 patient samples, and 2 samples of caregivers of patients, with a total of 159 participants. The 5 most commonly endorsed causal attributions of mental illness are discussed: (a) drug-related causes, including ganja (marijuana); (b) biological causes, such as chemical imbalance, familial transmission, and "blood"; (c) psychological causes, including stress and thinking too much; (d) social causes, such as relationship problems and job loss; and (e) spiritual or religious causes, including Obeah. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  7. Exploring the causal effect of interpretation bias on attachment expectations

    NARCIS (Netherlands)

    De Winter, S.; Bosmans, G.; Salemink, E.

    2017-01-01

    Attachment theory implies that children's inclination to interpret attachment figures behavior as supportive and available causally influences children's trust in their attachment figure's availability. An experiment was conducted to test whether training children (8–12 years old) to interpret

  8. Management’s causal reasoning on performance and earnings management

    NARCIS (Netherlands)

    Aerts, W.A.A.; Zhang, S.

    2014-01-01

    We investigate the association between the intensity of causal reasoning on performance in a firm’s annual management commentary and its earnings management propensity. Anticipated earnings management concerns are argued to constitute a significant accountability predicament, bringing management to

  9. Positive affect increases secondary control among causally uncertain individuals.

    Science.gov (United States)

    Tobin, Stephanie J; George, Melanie P

    2015-01-01

    Secondary control (acceptance of and adjustment to negative events) is thought to promote positive affect. We examined the opposite path: could positive affect increase secondary control, particularly among individuals high in causal uncertainty, who stand to benefit from it the most? In two studies, participants completed a causal uncertainty scale, thought about a problem while listening to affect-inducing music or no music, and then completed items that assessed secondary control. In Study 1, the music induced positive or negative affect. In Study 2, the music induced affect that was high or low in activation and positive or negative in valence. In both studies, we found that positive affect-inducing music increased secondary control among high causal uncertainty participants. Furthermore, trait affect did not account for the effects of causal uncertainty, and music did not influence primary control. These findings show that secondary control can fluctuate as a function of state affect.

  10. Leadership in Orchestra Emerges from the Causal Relationships of Movement Kinematics: e35757

    National Research Council Canada - National Science Library

    Leonardo Badino; Yi Li; Sera Tokay; Laila Craighero; Rosario Canto; Yiannis Aloimonos; Luciano Fadiga

    2012-01-01

    .... To this end, we recorded violinists' and conductors' movement kinematics during execution of Mozart pieces, searching for causal relationships among musicians by using the Granger Causality method (GC...

  11. Leadership in orchestra emerges from the causal relationships of movement kinematics

    National Research Council Canada - National Science Library

    D'Ausilio, Alessandro; Badino, Leonardo; Li, Yi; Tokay, Sera; Craighero, Laila; Canto, Rosario; Aloimonos, Yiannis; Fadiga, Luciano

    2012-01-01

    .... To this end, we recorded violinists' and conductors' movement kinematics during execution of Mozart pieces, searching for causal relationships among musicians by using the Granger Causality method (GC...

  12. Multiple Access Channels with States Causally Known at Transmitters

    OpenAIRE

    Li, Min; Simeone, Osvaldo; Yener, Aylin

    2010-01-01

    It has been recently shown by Lapidoth and Steinberg that strictly causal state information can be beneficial in multiple access channels (MACs). Specifically, it was proved that the capacity region of a two-user MAC with independent states, each known strictly causally to one encoder, can be enlarged by letting the encoders send compressed past state information to the decoder. In this work, a generalization of the said strategy is proposed whereby the encoders compress also the past transmi...

  13. Causal Inference and Observational Research: The Utility of Twins

    OpenAIRE

    McGue, Matt; Osler, Merete; Christensen, Kaare

    2010-01-01

    Valid causal inference is central to progress in theoretical and applied psychology. Although the randomized experiment is widely considered the gold standard for determining whether a given exposure increases the likelihood of some specified outcome, experiments are not always feasible and in some cases can result in biased estimates of causal effects. Alternatively, standard observational approaches are limited by the possibility of confounding, reverse causation, and the nonrandom distribu...

  14. An Experimental Research on Causal Illusion (in Chinese)

    OpenAIRE

    Shao, Z. F.; Zhao, J.

    2004-01-01

    The research examined humans’ causal attribution of response-outcome under controllable and uncontrollable conditions respectively and attempted to find out whether providing appropriate external cues could be beneficial to them in making accurate judgments. The results indicate: 1) under controllable conditions, the delay of feedback might lead to causal illusion; 2) under uncontrollable conditions, the subjects developed superstition and illusion of control rather than helplessness; 3) prov...

  15. Informational and Causal Architecture of Continuous-time Renewal Processes

    Science.gov (United States)

    Marzen, Sarah; Crutchfield, James P.

    2017-07-01

    We introduce the minimal maximally predictive models (ɛ {-machines }) of processes generated by certain hidden semi-Markov models. Their causal states are either discrete, mixed, or continuous random variables and causal-state transitions are described by partial differential equations. As an application, we present a complete analysis of the ɛ {-machines } of continuous-time renewal processes. This leads to closed-form expressions for their entropy rate, statistical complexity, excess entropy, and differential information anatomy rates.

  16. Modular and Flexible Causality Control on the Web

    OpenAIRE

    Leger, Paul; Tanter, Éric; Douence, Rémi

    2011-01-01

    Ajax has allowed JavaScript programmers to create interactive, collaborative, and user-centered Web applications, known as Web 2.0 Applications. These Web applications behave as distributed systems because processors are user machines that are used to send and receive messages between one another. Unsurprisingly, these applications have to address the same causality issues present in distributed systems like the need a) to control the causality between messages sent and responses received and...

  17. Effects of question formats on causal judgments and model evaluation.

    Science.gov (United States)

    Shou, Yiyun; Smithson, Michael

    2015-01-01

    Evaluation of causal reasoning models depends on how well the subjects' causal beliefs are assessed. Elicitation of causal beliefs is determined by the experimental questions put to subjects. We examined the impact of question formats commonly used in causal reasoning research on participant's responses. The results of our experiment (Study 1) demonstrate that both the mean and homogeneity of the responses can be substantially influenced by the type of question (structure induction versus strength estimation versus prediction). Study 2A demonstrates that subjects' responses to a question requiring them to predict the effect of a candidate cause can be significantly lower and more heterogeneous than their responses to a question asking them to diagnose a cause when given an effect. Study 2B suggests that diagnostic reasoning can strongly benefit from cues relating to temporal precedence of the cause in the question. Finally, we evaluated 16 variations of recent computational models and found the model fitting was substantially influenced by the type of questions. Our results show that future research in causal reasoning should place a high priority on disentangling the effects of question formats from the effects of experimental manipulations, because that will enable comparisons between models of causal reasoning uncontaminated by method artifact.

  18. Testing Quantum Mechanics with Observations of Causally Disconnected Cosmological Events

    Science.gov (United States)

    Friedman, Andrew S.; Kaiser, D. I.; Gallicchio, J.; Guth, A. H.

    2014-01-01

    We discuss a thought experiment which would leverage cosmology to test quantum mechanics using astronomical observations. Specifically, we aim to close the "settings-independence" loophole in experimental tests of Bell's inequality by choosing the detector settings (e.g. polarizer orientations) using real-time observations of causally disconnected cosmic sources. This would help close one of the most important remaining Bell test loopholes whereby a local hidden variable theory could mimic the quantum predictions if the experimental settings choices shared even a small correlation due to unknown local causal influences prior to the experiment. The talk will focus on the theoretical cosmology constraints needed to choose optimal sources for such an experiment, describing general conditions for pairs of cosmic events with arbitrary redshifts and angular separations to have shared causal pasts in Friedman-Lemaitre-Robertson-Walker universes with arbitrary curvature, including flat, dark energy dominated, accelerating universes like our own. While causally disjoint patches of the cosmic microwave background radiation at redshift z ~ 1090 could be used to set the detectors, z > 3.65 quasars observed at optical wavelengths are arguably the optimal candidate source pairs using present technology that meet the condition of having no shared causal past since the end of any period of inflation, 13.82 Gyr ago. Results are illustrated for our universe with causal structure animations to help visualize the intersections of past light cones for arbitrary event pairs.

  19. Whose statistical reasoning is facilitated by a causal structure intervention?

    Science.gov (United States)

    McNair, Simon; Feeney, Aidan

    2015-02-01

    People often struggle when making Bayesian probabilistic estimates on the basis of competing sources of statistical evidence. Recently, Krynski and Tenenbaum (Journal of Experimental Psychology: General, 136, 430-450, 2007) proposed that a causal Bayesian framework accounts for peoples' errors in Bayesian reasoning and showed that, by clarifying the causal relations among the pieces of evidence, judgments on a classic statistical reasoning problem could be significantly improved. We aimed to understand whose statistical reasoning is facilitated by the causal structure intervention. In Experiment 1, although we observed causal facilitation effects overall, the effect was confined to participants high in numeracy. We did not find an overall facilitation effect in Experiment 2 but did replicate the earlier interaction between numerical ability and the presence or absence of causal content. This effect held when we controlled for general cognitive ability and thinking disposition. Our results suggest that clarifying causal structure facilitates Bayesian judgments, but only for participants with sufficient understanding of basic concepts in probability and statistics.

  20. Causal Bayes Model of Mathematical Competence in Kindergarten

    Directory of Open Access Journals (Sweden)

    Božidar Tepeš

    2016-06-01

    Full Text Available In this paper authors define mathematical competences in the kindergarten. The basic objective was to measure the mathematical competences or mathematical knowledge, skills and abilities in mathematical education. Mathematical competences were grouped in the following areas: Arithmetic and Geometry. Statistical set consisted of 59 children, 65 to 85 months of age, from the Kindergarten Milan Sachs from Zagreb. The authors describe 13 variables for measuring mathematical competences. Five measuring variables were described for the geometry, and eight measuring variables for the arithmetic. Measuring variables are tasks which children solved with the evaluated results. By measuring mathematical competences the authors make causal Bayes model using free software Tetrad 5.2.1-3. Software makes many causal Bayes models and authors as experts chose the model of the mathematical competences in the kindergarten. Causal Bayes model describes five levels for mathematical competences. At the end of the modeling authors use Bayes estimator. In the results, authors describe by causal Bayes model of mathematical competences, causal effect mathematical competences or how intervention on some competences cause other competences. Authors measure mathematical competences with their expectation as random variables. When expectation of competences was greater, competences improved. Mathematical competences can be improved with intervention on causal competences. Levels of mathematical competences and the result of intervention on mathematical competences can help mathematical teachers.

  1. Increasing fMRI sampling rate improves Granger causality estimates.

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    Fa-Hsuan Lin

    Full Text Available Estimation of causal interactions between brain areas is necessary for elucidating large-scale functional brain networks underlying behavior and cognition. Granger causality analysis of time series data can quantitatively estimate directional information flow between brain regions. Here, we show that such estimates are significantly improved when the temporal sampling rate of functional magnetic resonance imaging (fMRI is increased 20-fold. Specifically, healthy volunteers performed a simple visuomotor task during blood oxygenation level dependent (BOLD contrast based whole-head inverse imaging (InI. Granger causality analysis based on raw InI BOLD data sampled at 100-ms resolution detected the expected causal relations, whereas when the data were downsampled to the temporal resolution of 2 s typically used in echo-planar fMRI, the causality could not be detected. An additional control analysis, in which we SINC interpolated additional data points to the downsampled time series at 0.1-s intervals, confirmed that the improvements achieved with the real InI data were not explainable by the increased time-series length alone. We therefore conclude that the high-temporal resolution of InI improves the Granger causality connectivity analysis of the human brain.

  2. Knowledge Representation Standards and Interchange Formats for Causal Graphs

    Science.gov (United States)

    Throop, David R.; Malin, Jane T.; Fleming, Land

    2005-01-01

    In many domains, automated reasoning tools must represent graphs of causally linked events. These include fault-tree analysis, probabilistic risk assessment (PRA), planning, procedures, medical reasoning about disease progression, and functional architectures. Each of these fields has its own requirements for the representation of causation, events, actors and conditions. The representations include ontologies of function and cause, data dictionaries for causal dependency, failure and hazard, and interchange formats between some existing tools. In none of the domains has a generally accepted interchange format emerged. The paper makes progress towards interoperability across the wide range of causal analysis methodologies. We survey existing practice and emerging interchange formats in each of these fields. Setting forth a set of terms and concepts that are broadly shared across the domains, we examine the several ways in which current practice represents them. Some phenomena are difficult to represent or to analyze in several domains. These include mode transitions, reachability analysis, positive and negative feedback loops, conditions correlated but not causally linked and bimodal probability distributions. We work through examples and contrast the differing methods for addressing them. We detail recent work in knowledge interchange formats for causal trees in aerospace analysis applications in early design, safety and reliability. Several examples are discussed, with a particular focus on reachability analysis and mode transitions. We generalize the aerospace analysis work across the several other domains. We also recommend features and capabilities for the next generation of causal knowledge representation standards.

  3. Tracking the evolution of causal cognition in humans.

    Science.gov (United States)

    Lombard, Marlize; Gärdenfors, Peter

    2017-12-30

    We suggest a seven-grade model for the evolution of causal cognition as a framework that can be used to gauge variation in the complexity of causal reasoning from the panin-hominin split until the appearance of cognitively modern hunter-gatherer communities. The intention is to put forward a cohesive model for the evolution of causal cognition in humans, which can be assessed against increasingly fine-grained empirical data from the palaeoanthropological and archaeological records. We propose that the tracking behaviour (i.e., the ability to interpret and follow external, inanimate, visual clues of hominins) provides a rich case study for tracing the evolution of causal cognition in our lineage. The grades of causal cognition are tentatively linked to aspects of the Stone Age/Palaeolithic archaeological record. Our model can also be applied to current work in evolutionary psychology and research on causal cognition, so that an inter-disciplinary understanding and correlation of processes becomes increasingly possible.

  4. Co-culturing of Fungal Strains Against Botrytis cinerea as a Model for the Induction of Chemical Diversity and Therapeutic Agents

    Science.gov (United States)

    Serrano, Rachel; González-Menéndez, Víctor; Rodríguez, Lorena; Martín, Jesús; Tormo, José R.; Genilloud, Olga

    2017-01-01

    New fungal SMs (SMs) have been successfully described to be produced by means of in vitro-simulated microbial community interactions. Co-culturing of fungi has proved to be an efficient way to induce cell–cell interactions that can promote the activation of cryptic pathways, frequently silent when the strains are grown in laboratory conditions. Filamentous fungi represent one of the most diverse microbial groups known to produce bioactive natural products. Triggering the production of novel antifungal compounds in fungi could respond to the current needs to fight health compromising pathogens and provide new therapeutic solutions. In this study, we have selected the fungus Botrytis cinerea as a model to establish microbial interactions with a large set of fungal strains related to ecosystems where they can coexist with this phytopathogen, and to generate a collection of extracts, obtained from their antagonic microbial interactions and potentially containing new bioactive compounds. The antifungal specificity of the extracts containing compounds induced after B. cinerea interaction was determined against two human fungal pathogens (Candida albicans and Aspergillus fumigatus) and three phytopathogens (Colletotrichum acutatum, Fusarium proliferatum, and Magnaporthe grisea). In addition, their cytotoxicity was also evaluated against the human hepatocellular carcinoma cell line (HepG2). We have identified by LC-MS the production of a wide variety of known compounds induced from these fungal interactions, as well as novel molecules that support the potential of this approach to generate new chemical diversity and possible new therapeutic agents. PMID:28469610

  5. Causal inference regarding infectious aetiology of chronic conditions: a systematic review.

    Directory of Open Access Journals (Sweden)

    Sofia Orrskog

    Full Text Available BACKGROUND: The global burden of disease has shifted from communicable diseases in children to chronic diseases in adults. This epidemiologic shift varies greatly by region, but in Europe, chronic conditions account for 86% of all deaths, 77% of the disease burden, and up to 80% of health care expenditures. A number of risk factors have been implicated in chronic diseases, such as exposure to infectious agents. A number of associations have been well established while others remain uncertain. METHODS AND FINDINGS: We assessed the body of evidence regarding the infectious aetiology of chronic diseases in the peer-reviewed literature over the last decade. Causality was assessed with three different criteria: First, the total number of associations documented in the literature between each infectious agent and chronic condition; second, the epidemiologic study design (quality of the study; third, evidence for the number of Hill's criteria and Koch's postulates that linked the pathogen with the chronic condition. We identified 3136 publications, of which 148 were included in the analysis. There were a total of 75 different infectious agents and 122 chronic conditions. The evidence was strong for five pathogens, based on study type, strength and number of associations; they accounted for 60% of the associations documented in the literature. They were human immunodeficiency virus, hepatitis C virus, Helicobacter pylori, hepatitis B virus, and Chlamydia pneumoniae and were collectively implicated in the aetiology of 37 different chronic conditions. Other pathogens examined were only associated with very few chronic conditions (≤ 3 and when applying the three different criteria of evidence the strength of the causality was weak. CONCLUSIONS: Prevention and treatment of these five pathogens lend themselves as effective public health intervention entry points. By concentrating research efforts on these promising areas, the human, economic, and societal

  6. Agility: Agent - Ility Architecture

    National Research Council Canada - National Science Library

    Thompson, Craig

    2002-01-01

    ...., object and web technologies). The objective of the Agility project is to develop an open agent grid architecture populated with scalable, deployable, industrial strength agent grid components, targeting the theme 'agents for the masses...

  7. Riot Control Agents

    Science.gov (United States)

    ... Submit What's this? Submit Button Facts About Riot Control Agents Interim document Recommend on Facebook Tweet Share Compartir FACT SHEET What riot control agents are Riot control agents (sometimes referred to ...

  8. Interacting agents in finance

    NARCIS (Netherlands)

    Hommes, C.; Durlauf, S.N.; Blume, L.E.

    2008-01-01

    Interacting agents in finance represent a behavioural, agent-based approach in which financial markets are viewed as complex adaptive systems consisting of many boundedly rational agents interacting through simple heterogeneous investment strategies, constantly adapting their behaviour in response

  9. Enhancing scientific reasoning by refining students' models of multivariable causality

    Science.gov (United States)

    Keselman, Alla

    Inquiry learning as an educational method is gaining increasing support among elementary and middle school educators. In inquiry activities at the middle school level, students are typically asked to conduct investigations and infer causal relationships about multivariable causal systems. In these activities, students usually demonstrate significant strategic weaknesses and insufficient metastrategic understanding of task demands. Present work suggests that these weaknesses arise from students' deficient mental models of multivariable causality, in which effects of individual features are neither additive, nor constant. This study is an attempt to develop an intervention aimed at enhancing scientific reasoning by refining students' models of multivariable causality. Three groups of students engaged in a scientific investigation activity over seven weekly sessions. By creating unique combinations of five features potentially involved in earthquake mechanism and observing associated risk meter readings, students had to find out which of the features were causal, and to learn to predict earthquake risk. Additionally, students in the instructional and practice groups engaged in self-directed practice in making scientific predictions. The instructional group also participated in weekly instructional sessions on making predictions based on multivariable causality. Students in the practice and instructional conditions showed small to moderate improvement in their attention to the evidence and in their metastrategic ability to recognize effective investigative strategies in the work of other students. They also demonstrated a trend towards making a greater number of valid inferences than the control group students. Additionally, students in the instructional condition showed significant improvement in their ability to draw inferences based on multiple records. They also developed more accurate knowledge about non-causal features of the system. These gains were maintained

  10. UMA TEORÍA CAUSAL PARA LOS CASOS FREGE

    Directory of Open Access Journals (Sweden)

    ABEL WAJNERMAN PAZ

    2015-06-01

    Full Text Available Fodor ha argumentado a favor de un par de tesis que pueden caracterizarse como constituyendo un dilema: Por un lado, si adoptamos una teoría funcional para los conceptos explicamos semánticamente los casos Frege pero caemos en el holismo semántico. Por otro lado, si adoptamos una teoría causal/informacional evitamos el holismo pero no explicamos los casos Frege semánticamente. Fodor (por ej, 1994, 1998 y 2008 intenta evitar la segunda parte del dilema argumentando que los casos de Frege pueden tener una explicación sintáctica y no semántica. En este trabajo intentaré ofrecer una salida alternativa al dilema fodoriano. Propondré una explicación semántica de los casos Frege que incorpora tanto elementos de una teoría causal como de una de rol funcional. Afirmaré que el contenido cognitivo o estrecho de un concepto (el tipo de contenido aparentemente exigido por los casos Frege es el conjunto de contenidos causales/informacionales de las representaciones que figuran en su rol funcional. Considero que individuar a las representaciones en los roles por medio de sus contenidos causales permite evitar el holismo (evitando el proceso de ramsificación típicamente empleado para individuar a los roles y que identificar el contenido cognitivo con contenidos causales/informacionales de las representaciones en los roles permite evitar el referencialismo de las propuestas causales (podemos distinguir sentido de referencia en términos causales.

  11. Physical constraints on causality-violating spacetimes in general relativity

    Science.gov (United States)

    Janca, Andrew Joseph

    The theoretical possibility of global causality violation has long been a problem within general relativity, for there exists a large number of model spacetimes known to admit closed time-like curves, trajectories allowing a timelike observer to return to some point in her own past. However, nearly all such known models have some unphysical feature. These physicality issues rendered causality-violation to the status of an interesting but safely theoretical problem until twenty years ago, when the appearance of a new type of causality-violating model spacetime and the subsequent proliferation of new models admitting closed timelike curves forced the attention of the community to the issue, and made causality violation and its possible physical consequences an active area of research within general relativity. This paper focuses on some of the older causality-violating spacetimes which model matter sources with cylindrical symmetry. By describing how cylindrically-symmetric solutions can be embedded within a spatially bounded and physically realistic body which outwardly has the symmetry of a torus or ring, it is shown that the chief problem of physical plausibility which these older solutions possess can be resolved. The intention is to make these models active candidates for consideration in future experiments to test general relativity's prediction that causality violation is a phenomenon that could be observed in the real world. Attending chapters describe physical systems other than rotating objects that can alter a local observer's experience of time to a substantial extent, including an electrically-charged massive shell slowing time in its interior (though not affecting causality) and a class of trajectories in the Reissner-Nordstrom background that could in principle allow a timelike observer to reverse her personal arrow of time relative to other observers in the spacetime as a whole. The paper concludes with a discussion of one of the plausibility problems

  12. Sensitivity Analysis and Bounding of Causal Effects with Alternative Identifying Assumptions

    Science.gov (United States)

    Jo, Booil; Vinokur, Amiram D.

    2011-01-01

    When identification of causal effects relies on untestable assumptions regarding nonidentified parameters, sensitivity of causal effect estimates is often questioned. For proper interpretation of causal effect estimates in this situation, deriving bounds on causal parameters or exploring the sensitivity of estimates to scientifically plausible…

  13. Opening the Black Box and Searching for Smoking Guns: Process Causality in Qualitative Research

    Science.gov (United States)

    Bennett, Elisabeth E.; McWhorter, Rochell R.

    2016-01-01

    Purpose: The purpose of this paper is to explore the role of qualitative research in causality, with particular emphasis on process causality. In one paper, it is not possible to discuss all the issues of causality, but the aim is to provide useful ways of thinking about causality and qualitative research. Specifically, a brief overview of the…

  14. Information flow and causality as rigorous notions ab initio

    Science.gov (United States)

    Liang, X. San

    2016-11-01

    Information flow or information transfer the widely applicable general physics notion can be rigorously derived from first principles, rather than axiomatically proposed as an ansatz. Its logical association with causality is firmly rooted in the dynamical system that lies beneath. The principle of nil causality that reads, an event is not causal to another if the evolution of the latter is independent of the former, which transfer entropy analysis and Granger causality test fail to verify in many situations, turns out to be a proven theorem here. Established in this study are the information flows among the components of time-discrete mappings and time-continuous dynamical systems, both deterministic and stochastic. They have been obtained explicitly in closed form, and put to applications with the benchmark systems such as the Kaplan-Yorke map, Rössler system, baker transformation, Hénon map, and stochastic potential flow. Besides unraveling the causal relations as expected from the respective systems, some of the applications show that the information flow structure underlying a complex trajectory pattern could be tractable. For linear systems, the resulting remarkably concise formula asserts analytically that causation implies correlation, while correlation does not imply causation, providing a mathematical basis for the long-standing philosophical debate over causation versus correlation.

  15. Formalizing Neurath's ship: Approximate algorithms for online causal learning.

    Science.gov (United States)

    Bramley, Neil R; Dayan, Peter; Griffiths, Thomas L; Lagnado, David A

    2017-04-01

    Higher-level cognition depends on the ability to learn models of the world. We can characterize this at the computational level as a structure-learning problem with the goal of best identifying the prevailing causal relationships among a set of relata. However, the computational cost of performing exact Bayesian inference over causal models grows rapidly as the number of relata increases. This implies that the cognitive processes underlying causal learning must be substantially approximate. A powerful class of approximations that focuses on the sequential absorption of successive inputs is captured by the Neurath's ship metaphor in philosophy of science, where theory change is cast as a stochastic and gradual process shaped as much by people's limited willingness to abandon their current theory when considering alternatives as by the ground truth they hope to approach. Inspired by this metaphor and by algorithms for approximating Bayesian inference in machine learning, we propose an algorithmic-level model of causal structure learning under which learners represent only a single global hypothesis that they update locally as they gather evidence. We propose a related scheme for understanding how, under these limitations, learners choose informative interventions that manipulate the causal system to help elucidate its workings. We find support for our approach in the analysis of 3 experiments. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  16. Causal illusions in children when the outcome is frequent.

    Directory of Open Access Journals (Sweden)

    María Manuela Moreno-Fernández

    Full Text Available Causal illusions occur when people perceive a causal relation between two events that are actually unrelated. One factor that has been shown to promote these mistaken beliefs is the outcome probability. Thus, people tend to overestimate the strength of a causal relation when the potential consequence (i.e. the outcome occurs with a high probability (outcome-density bias. Given that children and adults differ in several important features involved in causal judgment, including prior knowledge and basic cognitive skills, developmental studies can be considered an outstanding approach to detect and further explore the psychological processes and mechanisms underlying this bias. However, the outcome density bias has been mainly explored in adulthood, and no previous evidence for this bias has been reported in children. Thus, the purpose of this study was to extend outcome-density bias research to childhood. In two experiments, children between 6 and 8 years old were exposed to two similar setups, both showing a non-contingent relation between the potential cause and the outcome. These two scenarios differed only in the probability of the outcome, which could either be high or low. Children judged the relation between the two events to be stronger in the high probability of the outcome setting, revealing that, like adults, they develop causal illusions when the outcome is frequent.

  17. On the Temporal Causal Relationship Between Macroeconomic Variables

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    Srinivasan Palamalai

    2014-02-01

    Full Text Available The present study examines the dynamic interactions among macroeconomic variables such as real output, prices, money supply, interest rate (IR, and exchange rate (EXR in India during the pre-economic crisis and economic crisis periods, using the autoregressive distributed lag (ARDL bounds test for cointegration, Johansen and Juselius multivariate cointegration test, Granger causality/Block exogeneity Wald test based on Vector Error Correction Model, variance decomposition analysis and impulse response functions. The empirical results reveal a stronger long-run bilateral relationship between real output, price level, IR, and EXR during the pre-crisis sample period. Moreover, the empirical results confirm a unidirectional short-run causality running from price level to EXR, IR to price level, and real output to money supply during the pre-crisis period. Also, it is evident from the test results that there exist short-run bidirectional relationships running between real output and EXR, price level and IR, and IR and EXR in the pre-crisis era, respectively. Most importantly, long-run bidirectional causality is found between real output, EXR, and IR during the economic crisis period. And the study results indicate short-run bidirectional causality between money supply and EXR, IR and price level, and IR and output in India during the crisis era. Also, a short-run unidirectional causality runs from prices to real output in the crisis period.

  18. The Causal Relationship between Health and Education Expenditures in Malaysia

    Directory of Open Access Journals (Sweden)

    Chor Foon TANG

    2011-08-01

    Full Text Available A major macroeconomic policy in generating economic growth is to encourage investments on human capital such as health and education. This is because both health and education make significant contribution to increasing productivity of the labour force which ultimately exerts a positive effect on raising output levels. A question that arises is whether investments on health and education have a causal relationship and if so, what is the directional causality? The objective of this study is to examine the causal relationship between health and education expenditures in Malaysia. This study covered annual data from 1970 to 2007. Using Granger causality as well as Toda and Yamamoto MWALD causality approaches, this study suggests that education Granger-causes health expenditure in both the short run and long run. The findings of this study implied that the Malaysian society places preference on education expenditure rather than health. This preference is not unexpected as generally, an educated and knowledgeable society precedes a healthy one. Before a society has attained a relatively higher level of education, it is less aware of the importance of health. Thus, expenditure on education should lead expenditure on health.

  19. Causal attributions in Brazilian children's reasoning about health and illness

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    Boruchovitch Evely

    2000-01-01

    Full Text Available INTRODUCTION: At a time when a great number of diseases can be prevented by changing one's habits and life style, investigations have focused on understanding what adults and children believe to be desirable health practices and uncovering the factors associated with successful adherence to such practices. For these, causal attributions for health and illness were investigated among 96 Brazilian elementary school students. METHODS: Ninety six subjects, aged 6 to 14, were interviewed individually and their causal attributions were assessed through 14 true-false items (e.g. people stay well [healthy] because they are lucky. The relationship between the children's causal attributions and demographic characteristics were also examined. RESULTS: Overall, the results were consistent with previous researches. "Taking care of oneself" was considered the most important cause of good health. "Viruses and germs" and "lack of self-care" were the most selected causes of illness. Analyses revealed significant relationship between subjects' causal attribution and their age, school grade level, socioeconomic status and gender. CONCLUSIONS: The study findings suggest that there may be more cross-cultural similarities than differences in children's causal attributions for health and illness. Finding ways to help individuals engage in appropriate preventive-maintenance health practices without developing an exaggerated notion that the individuals can control their own health and illness is a challenge which remains to be addressed by further research.

  20. Corporate Governance and Financial Performance Nexus: Any Bidirectional Causality?

    Directory of Open Access Journals (Sweden)

    Alley Ibrahim S.

    2016-06-01

    Full Text Available Most studies on corporate governance recognize endogeneity in the nexus between corporate governance and financial performance. Little attention has, however, been paid to the direction of causality between the two phenomena, and hence the Vector Error Correction (VEC model, which allows for endogenous determination of the direction of causality, has not been widely employed. This study fills that gap by estimating the nexus and the direction of causality using the VEC model to analyze panel data on selected listed firms in Nigeria. The results agree with the findings of most previous studies that corporate governance significantly affects financial performance. Board skills, board composition and management skills enhanced financial performance indicators – return on equity (ROE, return on asset (ROA and net profit margin (NPM; in many occasions, significantly. Board size and audit committee size did not, and can actually undermine financial performance. More importantly, financial performance did not significantly affect corporate governance. On the basis of the lag structure of the VEC model, this study affirms unidirectional causality in the nexus, running from corporate governance to financial performance, nullifying the hypothesis of bidirectional causality in the nexus.

  1. Illusions of causality at the heart of pseudoscience.

    Science.gov (United States)

    Matute, Helena; Yarritu, Ion; Vadillo, Miguel A

    2011-08-01

    Pseudoscience, superstitions, and quackery are serious problems that threaten public health and in which many variables are involved. Psychology, however, has much to say about them, as it is the illusory perceptions of causality of so many people that needs to be understood. The proposal we put forward is that these illusions arise from the normal functioning of the cognitive system when trying to associate causes and effects. Thus, we propose to apply basic research and theories on causal learning to reduce the impact of pseudoscience. We review the literature on the illusion of control and the causal learning traditions, and then present an experiment as an illustration of how this approach can provide fruitful ideas to reduce pseudoscientific thinking. The experiment first illustrates the development of a quackery illusion through the testimony of fictitious patients who report feeling better. Two different predictions arising from the integration of the causal learning and illusion of control domains are then proven effective in reducing this illusion. One is showing the testimony of people who feel better without having followed the treatment. The other is asking participants to think in causal terms rather than in terms of effectiveness. ©2010 The British Psychological Society.

  2. Emergence of Space-Time from Topologically Homogeneous Causal Networks

    CERN Document Server

    D'Ariano, Giacomo Mauro

    2011-01-01

    In this paper we study the emergence of Minkowski space-time from a causal network. Differently from previous approaches, we require the network to be topologically homogeneous, so that the metric is derived from pure event-counting. Emergence from events has an operational motivation in requiring that every physical quantity---including space-time---be defined through precise measurement procedures. Topological homogeneity is a requirement for having space-time metric emergent from the pure topology of causal connections, whereas physically corresponds to the universality of the physical law. We analyze in detail the case of 1+1 dimension. Coordinate systems are established via an Einsteinian protocol, and lead to a digital version of the Lorentz transformations. In a computational analogy, the foliation construction can also be regarded as the synchronization with a global clock of the calls to independent subroutines (corresponding to the causally independent events) in a parallel distributed computation, ...

  3. Capturing connectivity and causality in complex industrial processes

    CERN Document Server

    Yang, Fan; Shah, Sirish L; Chen, Tongwen

    2014-01-01

    This brief reviews concepts of inter-relationship in modern industrial processes, biological and social systems. Specifically ideas of connectivity and causality within and between elements of a complex system are treated; these ideas are of great importance in analysing and influencing mechanisms, structural properties and their dynamic behaviour, especially for fault diagnosis and hazard analysis. Fault detection and isolation for industrial processes being concerned with root causes and fault propagation, the brief shows that, process connectivity and causality information can be captured in two ways: ·      from process knowledge: structural modeling based on first-principles structural models can be merged with adjacency/reachability matrices or topology models obtained from process flow-sheets described in standard formats; and ·      from process data: cross-correlation analysis, Granger causality and its extensions, frequency domain methods, information-theoretical methods, and Bayesian ne...

  4. Causal Analysis for Performance Modeling of Computer Programs

    Directory of Open Access Journals (Sweden)

    Jan Lemeire

    2007-01-01

    Full Text Available Causal modeling and the accompanying learning algorithms provide useful extensions for in-depth statistical investigation and automation of performance modeling. We enlarged the scope of existing causal structure learning algorithms by using the form-free information-theoretic concept of mutual information and by introducing the complexity criterion for selecting direct relations among equivalent relations. The underlying probability distribution of experimental data is estimated by kernel density estimation. We then reported on the benefits of a dependency analysis and the decompositional capacities of causal models. Useful qualitative models, providing insight into the role of every performance factor, were inferred from experimental data. This paper reports on the results for a LU decomposition algorithm and on the study of the parameter sensitivity of the Kakadu implementation of the JPEG-2000 standard. Next, the analysis was used to search for generic performance characteristics of the applications.

  5. Predicting the Cosmological Constant from the Causal Entropic Principle

    Energy Technology Data Exchange (ETDEWEB)

    Bousso, Raphael; Bousso, Raphael; Harnik, Roni; Kribs, Graham D.; Perez, Gilad

    2007-05-01

    We compute the expected value of the cosmological constant in our universe from the Causal Entropic Principle. Since observers must obey the laws of thermodynamics and causality, the principle asserts that physical parameters are most likely to be found in the range of values for which the total entropy production within a causally connected region is maximized. Despite the absence of more explicit anthropic criteria, the resulting probability distribution turns out to be in excellent agreement with observation. In particular, we find that dust heated by stars dominates the entropy production, demonstrating the remarkable power of this thermodynamic selection criterion. The alternative approach-weighting by the number of"observers per baryon" -- is less well-defined, requires problematic assumptions about the nature of observers, and yet prefers values larger than present experimental bounds.

  6. Predicting the Cosmological Constant from the CausalEntropic Principle

    Energy Technology Data Exchange (ETDEWEB)

    Bousso, Raphael; Harnik, Roni; Kribs, Graham D.; Perez, Gilad

    2007-02-20

    We compute the expected value of the cosmological constant in our universe from the Causal Entropic Principle. Since observers must obey the laws of thermodynamics and causality, it asserts that physical parameters are most likely to be found in the range of values for which the total entropy production within a causally connected region is maximized. Despite the absence of more explicit anthropic criteria, the resulting probability distribution turns out to be in excellent agreement with observation. In particular, we find that dust heated by stars dominates the entropy production, demonstrating the remarkable power of this thermodynamic selection criterion. The alternative approach--weighting by the number of ''observers per baryon''--is less well-defined, requires problematic assumptions about the nature of observers, and yet prefers values larger than present experimental bounds.

  7. Structural equation modeling: building and evaluating causal models: Chapter 8

    Science.gov (United States)

    Grace, James B.; Scheiner, Samuel M.; Schoolmaster, Donald R.

    2015-01-01

    Scientists frequently wish to study hypotheses about causal relationships, rather than just statistical associations. This chapter addresses the question of how scientists might approach this ambitious task. Here we describe structural equation modeling (SEM), a general modeling framework for the study of causal hypotheses. Our goals are to (a) concisely describe the methodology, (b) illustrate its utility for investigating ecological systems, and (c) provide guidance for its application. Throughout our presentation, we rely on a study of the effects of human activities on wetland ecosystems to make our description of methodology more tangible. We begin by presenting the fundamental principles of SEM, including both its distinguishing characteristics and the requirements for modeling hypotheses about causal networks. We then illustrate SEM procedures and offer guidelines for conducting SEM analyses. Our focus in this presentation is on basic modeling objectives and core techniques. Pointers to additional modeling options are also given.

  8. Information-theoretic implications of quantum causal structures.

    Science.gov (United States)

    Chaves, Rafael; Majenz, Christian; Gross, David

    2015-01-06

    It is a relatively new insight of classical statistics that empirical data can contain information about causation rather than mere correlation. First algorithms have been proposed that are capable of testing whether a presumed causal relationship is compatible with an observed distribution. However, no systematic method is known for treating such problems in a way that generalizes to quantum systems. Here, we describe a general algorithm for computing information-theoretic constraints on the correlations that can arise from a given causal structure, where we allow for quantum systems as well as classical random variables. The general technique is applied to two relevant cases: first, we show that the principle of information causality appears naturally in our framework and go on to generalize and strengthen it. Second, we derive bounds on the correlations that can occur in a networked architecture, where a set of few-body quantum systems is distributed among some parties.

  9. Information–theoretic implications of quantum causal structures

    DEFF Research Database (Denmark)

    Chaves, Rafael; Majenz, Christian; Gross, David

    2015-01-01

    . However, no systematic method is known for treating such problems in a way that generalizes to quantum systems. Here, we describe a general algorithm for computing information–theoretic constraints on the correlations that can arise from a given causal structure, where we allow for quantum systems as well......It is a relatively new insight of classical statistics that empirical data can contain information about causation rather than mere correlation. First algorithms have been proposed that are capable of testing whether a presumed causal relationship is compatible with an observed distribution...... as classical random variables. The general technique is applied to two relevant cases: first, we show that the principle of information causality appears naturally in our framework and go on to generalize and strengthen it. Second, we derive bounds on the correlations that can occur in a networked architecture...

  10. Causal explanation, intentionality, and prediction: Evaluating the Criticism of "Deductivism"

    DEFF Research Database (Denmark)

    Koch, Carsten Allan

    2001-01-01

    In a number of influential contributions, Tony Lawson has attacked a view of science that he refers to as deductivism, and criticized economists for implicitly using it in their research. Lawson argues that deductivism is simply the covering-law model, also known as the causal model of scientific...... explanation (section 3). In the paper we refer to that model as that of causal explanation. Since this is the most generally accepted model of scientific explanation, this criticism has quite far-reaching implications. We argue that Lawson’s criticism of the causal model of scientific explanation is mistaken...... the question of whether the existence of free will excludes the possibility of prediction of behaviour by scientific or other methods. It is argued that, at least for an example, free will does not necessarily imply that the possibility of prediction of behaviour is ruled out. This section is, however, much...

  11. The latent causal chain of industrial water pollution in China.

    Science.gov (United States)

    Miao, Xin; Tang, Yanhong; Wong, Christina W Y; Zang, Hongyu

    2015-01-01

    The purpose of this paper is to discover the latent causal chain of industrial water pollution in China and find ways to cure the want on discharge of toxic waste from industries. It draws evidences from the past pollution incidents in China. Through further digging the back interests and relations by analyzing representative cases, extended theory about loophole derivations and causal chain effect is drawn. This theoretical breakthrough reflects deeper causality. Institutional defect instead of human error is confirmed as the deeper reason of frequent outbreaks of water pollution incidents in China. Ways for collaborative environmental governance are proposed. This paper contributes to a better understanding about the deep inducements of industrial water pollution in China, and, is meaningful for ensuring future prevention and mitigation of environmental pollution. It illuminates multiple dimensions for collaborative environmental governance to cure the stubborn problem.

  12. Causal Cognition, Force Dynamics and Early Hunting Technologies

    Directory of Open Access Journals (Sweden)

    Peter Gärdenfors

    2018-02-01

    Full Text Available With this contribution we analyze ancient hunting technologies as one way to explore the development of causal cognition in the hominin lineage. Building on earlier work, we separate seven grades of causal thinking. By looking at variations in force dynamics as a central element in causal cognition, we analyze the thinking required for different hunting technologies such as stabbing spears, throwing spears, launching atlatl darts, shooting arrows with a bow, and the use of poisoned arrows. Our interpretation demonstrates that there is an interplay between the extension of human body through technology and expanding our cognitive abilities to reason about causes. It adds content and dimension to the trend of including embodied cognition in evolutionary studies and in the interpretation of the archeological record. Our method could explain variation in technology sets between archaic and modern human groups.

  13. Momentary and integrative response strategies in causal judgment.

    Science.gov (United States)

    Collins, Darrell J; Shanks, David R

    2002-10-01

    Associative models of causal learning predict recency effects. Judgments at the end of a trial series should be strongly biased by recently presented information. Prior research, however, presents a contrasting picture of human performance. López, Shanks, Almaraz, and Fernández (1998) observed recency, whereas Dennis and Ahn (2001) found the opposite, primacy. Here we replicate both of these effects and provide an explanation for this paradox. Four experiments show that the effect of trial order on judgments is a function of judgment frequency, where incremental judgments lead to recency while single final judgments abolish recency and lead instead to integration of information across trials (i.e., primacy). These results challenge almost all existing accounts of causal judgment. We propose a modified associative account in which participants can base their causal judgments either on current associative strength (momentary strategy) or on the cumulative change in associative strength since the previous judgment (integrative strategy).

  14. Informational and Causal Architecture of Discrete-Time Renewal Processes

    Directory of Open Access Journals (Sweden)

    Sarah E. Marzen

    2015-07-01

    Full Text Available Renewal processes are broadly used to model stochastic behavior consisting of isolated events separated by periods of quiescence, whose durations are specified by a given probability law. Here, we identify the minimal sufficient statistic for their prediction (the set of causal states, calculate the historical memory capacity required to store those states (statistical complexity, delineate what information is predictable (excess entropy, and decompose the entropy of a single measurement into that shared with the past, future, or both. The causal state equivalence relation defines a new subclass of renewal processes with a finite number of causal states despite having an unbounded interevent count distribution. We use the resulting formulae to analyze the output of the parametrized Simple Nonunifilar Source, generated by a simple two-state hidden Markov model, but with an infinite-state ϵ-machine presentation. All in all, the results lay the groundwork for analyzing more complex processes with infinite statistical complexity and infinite excess entropy.

  15. The why of things: causality in science, medicine, and life

    CERN Document Server

    Rabins, Peter V.

    2013-01-01

    Why was there a meltdown at the Fukushima power plant? Why do some people get cancer and not others? Why is global warming happening? Why does one person get depressed in the face of life's vicissitudes while another finds resilience? Questions like these -- questions of causality -- form the basis of modern scientific inquiry, posing profound intellectual and methodological challenges for researchers in the physical, natural, biomedical, and social sciences. In this groundbreaking book, noted psychiatrist and author Peter Rabins offers a conceptual framework for analyzing daunting questions of causality. Navigating a lively intellectual voyage between the shoals of strict reductionism and relativism, Rabins maps a three-facet model of causality and applies it to a variety of questions in science, medicine, economics, and more. Throughout this book, Rabins situates his argument within relevant scientific contexts, such as quantum mechanics, cybernetics, chaos theory, and epigenetics. A renowned communicator o...

  16. A Causal Inference Analysis of the Effect of Wildland Fire ...

    Science.gov (United States)

    Wildfire smoke is a major contributor to ambient air pollution levels. In this talk, we develop a spatio-temporal model to estimate the contribution of fire smoke to overall air pollution in different regions of the country. We combine numerical model output with observational data within a causal inference framework. Our methods account for aggregation and potential bias of the numerical model simulation, and address uncertainty in the causal estimates. We apply the proposed method to estimation of ozone and fine particulate matter from wildland fires and the impact on health burden assessment. We develop a causal inference framework to assess contributions of fire to ambient PM in the presence of spatial interference.

  17. On the road toward formal reasoning: reasoning with factual causal and contrary-to-fact causal premises during early adolescence.

    Science.gov (United States)

    Markovits, Henry

    2014-12-01

    Understanding the development of conditional (if-then) reasoning is critical for theoretical and educational reasons. Here we examined the hypothesis that there is a developmental transition between reasoning with true and contrary-to-fact (CF) causal conditionals. A total of 535 students between 11 and 14 years of age received priming conditions designed to encourage use of either a true or CF alternatives generation strategy and reasoning problems with true causal and CF causal premises (with counterbalanced order). Results show that priming had no effect on reasoning with true causal premises. By contrast, priming with CF alternatives significantly improved logical reasoning with CF premises. Analysis of the effect of order showed that reasoning with CF premises reduced logical responding among younger students but had no effect among older students. Results support the idea that there is a transition in the reasoning processes in this age range associated with the nature of the alternatives generation process required for logical reasoning with true and CF causal conditionals. Copyright © 2014 Elsevier Inc. All rights reserved.

  18. An Algorithmic Information Calculus for Causal Discovery and Reprogramming Systems

    KAUST Repository

    Zenil, Hector

    2017-09-08

    We introduce a conceptual framework and an interventional calculus to steer and manipulate systems based on their intrinsic algorithmic probability using the universal principles of the theory of computability and algorithmic information. By applying sequences of controlled interventions to systems and networks, we estimate how changes in their algorithmic information content are reflected in positive/negative shifts towards and away from randomness. The strong connection between approximations to algorithmic complexity (the size of the shortest generating mechanism) and causality induces a sequence of perturbations ranking the network elements by the steering capabilities that each of them is capable of. This new dimension unmasks a separation between causal and non-causal components providing a suite of powerful parameter-free algorithms of wide applicability ranging from optimal dimension reduction, maximal randomness analysis and system control. We introduce methods for reprogramming systems that do not require the full knowledge or access to the system\\'s actual kinetic equations or any probability distributions. A causal interventional analysis of synthetic and regulatory biological networks reveals how the algorithmic reprogramming qualitatively reshapes the system\\'s dynamic landscape. For example, during cellular differentiation we find a decrease in the number of elements corresponding to a transition away from randomness and a combination of the system\\'s intrinsic properties and its intrinsic capabilities to be algorithmically reprogrammed can reconstruct an epigenetic landscape. The interventional calculus is broadly applicable to predictive causal inference of systems such as networks and of relevance to a variety of machine and causal learning techniques driving model-based approaches to better understanding and manipulate complex systems.

  19. Timing and causality in the generation of learned eyelid responses

    Directory of Open Access Journals (Sweden)

    Raudel eSánchez-Campusano

    2011-08-01

    Full Text Available The cerebellum-red nucleus-facial motoneuron (Mn pathway has been reported as being involved in the proper timing of classically conditioned eyelid responses. This special type of associative learning serves as a model of event timing for studying the role of the cerebellum in dynamic motor control. Here, we have re-analyzed the firing activities of cerebellar posterior interpositus (IP neurons and orbicularis oculi (OO Mns in alert behaving cats during classical eyeblink conditioning, using a delay paradigm. The aim was to revisit the hypothesis that the IP neurons can be considered a neuronal phase-modulating device supporting OO Mns firing with an emergent timing mechanism and an explicit correlation code during learned eyelid movements. Optimized experimental and computational tools allowed us to determine the different causal relationships (temporal order and correlation code during and between trials. These intra- and inter-trial timing strategies expanding from sub-second range (millisecond timing to longer-lasting ranges (interval timing expanded the functional domain of cerebellar timing beyond motor control. Interestingly, the results supported the above-mentioned hypothesis. The causal inferences were influenced by the precise motor and premotor spike-timing in the cause-effect interval, and, in addition, the timing of the learned responses depended on cerebellar-Mn network causality. Furthermore, the timing of CRs depended upon the probability of simulated causal conditions in the cause-effect interval and not the mere duration of the inter-stimulus interval. In this work, the close relation between timing and causality was verified. It could thus be concluded that the firing activities of IP neurons may be related more to the proper performance of ongoing CRs (i.e., the proper timing as a consequence of the pertinent causality than to their generation and/or initiation.

  20. Bayesian detection of causal rare variants under posterior consistency.

    KAUST Repository

    Liang, Faming

    2013-07-26

    Identification of causal rare variants that are associated with complex traits poses a central challenge on genome-wide association studies. However, most current research focuses only on testing the global association whether the rare variants in a given genomic region are collectively associated with the trait. Although some recent work, e.g., the Bayesian risk index method, have tried to address this problem, it is unclear whether the causal rare variants can be consistently identified by them in the small-n-large-P situation. We develop a new Bayesian method, the so-called Bayesian Rare Variant Detector (BRVD), to tackle this problem. The new method simultaneously addresses two issues: (i) (Global association test) Are there any of the variants associated with the disease, and (ii) (Causal variant detection) Which variants, if any, are driving the association. The BRVD ensures the causal rare variants to be consistently identified in the small-n-large-P situation by imposing some appropriate prior distributions on the model and model specific parameters. The numerical results indicate that the BRVD is more powerful for testing the global association than the existing methods, such as the combined multivariate and collapsing test, weighted sum statistic test, RARECOVER, sequence kernel association test, and Bayesian risk index, and also more powerful for identification of causal rare variants than the Bayesian risk index method. The BRVD has also been successfully applied to the Early-Onset Myocardial Infarction (EOMI) Exome Sequence Data. It identified a few causal rare variants that have been verified in the literature.