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  • Open Access English
    Authors: 
    Ivano Baronchelli; G. Rodighiero; Harry I. Teplitz; Claudia Scarlata; Alberto Franceschini; S. Berta; Laia Barrufet; Mattia Vaccari; Matteo Bonato; Laure Ciesla; +15 more
    Publisher: HAL CCSD
    Countries: France, Italy, United States
    Project: EC | HELP (607254)

    For a sample of star forming galaxies in the redshift interval 0.15$<$z$<$0.3, we study how both the relative strength of the AGN infra-red emission, compared to that due to the star formation (SF), and the numerical fraction of AGNs, change as a function of the total stellar mass of the hosting galaxy group (M$^{*}_{\mathrm{group}}$), between $10^{10.25}$ and $10^{11.9}$M$_{\odot}$. Using a multi-component SED fitting analysis, we separate the contribution of stars, AGN torus and star formation to the total emission at different wavelengths. This technique is applied to a new multi-wavelength data-set in the SIMES field (23 not redundant photometric bands), spanning the wavelength range from the UV (GALEX) to the far-IR (Herschel) and including crucial AKARI and WISE mid-IR observations (4.5 \mu m$<\lambda<$24 \mu m), where the BH thermal emission is stronger. This new photometric catalog, that includes our best photo-z estimates, is released through the NASA/IPAC Infrared Science Archive (IRSA). Groups are identified through a friends of friends algorithm ($\sim$62% purity, $\sim$51% completeness). We identified a total of 45 galaxies requiring an AGN emission component, 35 of which in groups and 10 in the field. We find BHAR$\propto ($M$^{*}_{\mathrm{group}})^{1.21\pm0.27}$ and (BHAR/SFR)$\propto ($M$^{*}_{\mathrm{group}})^{1.04\pm0.24}$ while, in the same range of M$^{*}_{\mathrm{group}}$, we do not observe any sensible change in the numerical fraction of AGNs. Our results indicate that the nuclear activity (i.e. the BHAR and the BHAR/SFR ratio) is enhanced when galaxies are located in more massive and richer groups. Comment: 31 pages, 23 figures

  • Open Access English
    Authors: 
    Golan Miller; Avital Beery; Prashant Kumar Singh; Fengde Wang; Rotem Zelingher; Etel Motenko; Michal Lieberman-Lazarovich;
    Publisher: Oxford University Press
    Country: France

    Abstract Climate change is causing temperature increment in crop production areas worldwide, generating conditions of heat stress that negatively affect crop productivity. Tomato (Solanum lycopersicum), a major vegetable crop, is highly susceptible to conditions of heat stress. When tomato plants are exposed to ambient day/night temperatures that exceed 32 °C/20 °C, respectively, during the reproductive phase, fruit set and fruit weight are reduced, leading to a significant decrease in yield. Processing tomato cultivars are cultivated in open fields, where environmental conditions are not controlled; therefore, plants are exposed to multiple abiotic stresses, including heat stress. Nonetheless, information on stress response in processing tomatoes is very limited. Understanding the physiological response of modern processing tomato cultivars to heat stress may facilitate the development of thermotolerant cultivars. Here, we compared two tomato processing cultivars, H4107 and H9780, that we found to be constantly differing in yield performance. Using field and temperature-controlled greenhouse experiments, we show that the observed difference in yield is attributed to the occurrence of heat stress conditions. In addition, fruit set and seed production were significantly higher in the thermotolerant cultivar H4107, compared with H9780. Despite the general acceptance of pollen viability as a measure of thermotolerance, there was no difference in the percentage of viable pollen between H4107 and H9780 under either of the conditions tested. In addition to observations of similar pollen germination and bud abscission rates, our results suggest that processing tomato cultivars may present a particular case, in which pollen performance is not determining reproductive thermotolerance. Our results also demonstrate the value of combining controlled and uncontrolled experimental settings, in order to validate and identify heat stress-related responses, thus facilitating the development of thermotolerant processing tomato cultivars. Our paper deals with the response of tomato plants to high temperatures. Tomato is an important crop, and tomato plants are very sensitive to high temperatures. Therefore, the increase in temperatures due to climate change poses a threat to tomato production. We found that a specific tomato cultivar is heat stress-tolerant, with better productivity under high temperatures. Usually, such tolerance is linked with pollen grains viability. Interestingly, in our case, pollen characteristics were eliminated as a causal factor for heat stress tolerance, meaning that other factors are involved. Follow-up studies are performed towards the development of heat-tolerant tomato.

  • Open Access English
    Authors: 
    Omer Edhan; Ziv Hellman; Ilan Nehama;
    Publisher: The Royal Society
    Country: United Kingdom

    AbstractWe consider genotypic convergence of populations and show that under fixed fitness asexual and haploid sexual populations attain monomorphic convergence (even under genetic linkage between loci) to basins of attraction with locally exponential convergence rates; the same convergence obtains in single locus diploid sexual reproduction but to polymorphic populations. Furthermore, we show that there is a unified underlying theory underlying these convergences: all of them can be interpreted as instantiations of players in a potential game implementing a multiplicative weights updating algorithm to converge to equilibrium, making use of the Baum–Eagon Theorem. To analyse varying environments, we introduce the concept of ‘virtual convergence’, under which, even if fixation is not attained, the population nevertheless achieves the fitness growth rate it would have had under convergence to an optimal genotype. Virtual convergence is attained by asexual, haploid sexual, and multi-locus diploid reproducing populations, even if environments vary arbitrarily. We also study conditions for true monomorphic convergence in asexually reproducing populations in varying environments.

  • Publication . Article . Preprint . 2017
    Open Access English
    Authors: 
    Kyle Kawagoe; Greg Huber; Marc Pradas; Michael Wilkinson; Alain Pumir; Eli Ben-Naim;

    We investigate statistical properties of trails formed by a random process incorporating aggregation, fragmentation, and diffusion. In this stochastic process, which takes place in one spatial dimension, two neighboring trails may combine to form a larger one and also, one trail may split into two. In addition, trails move diffusively. The model is defined by two parameters which quantify the fragmentation rate and the fragment size. In the long-time limit, the system reaches a steady state, and our focus is the limiting distribution of trail weights. We find that the density of trail weight has power-law tail $P(w) \sim w^{-\gamma}$ for small weight $w$. We obtain the exponent $\gamma$ analytically, and find that it varies continuously with the two model parameters. The exponent $\gamma$ can be positive or negative, so that in one range of parameters small-weight tails are abundant, and in the complementary range, they are rare. Comment: 8 pages, 8 figures

  • Open Access English
    Authors: 
    M. D. Petrović; Goran Gligorić; Aleksandra Maluckov; Lj. Hadžievski; Boris A. Malomed;
    Country: Serbia
    Project: MESTD | Photonics of micro and na... (45010)

    Existence, stability and dynamics of soliton complexes, centered at the site of a single transverse link connecting two parallel 2D (two-dimensional) lattices, are investigated. The system with the on-site cubic self-focusing nonlinearity is modeled by the pair of discrete nonlinear Schr\"{o}dinger equations linearly coupled at the single site. Symmetric, antisymmetric and asymmetric complexes are constructed by means of the variational approximation (VA) and numerical methods. The VA demonstrates that the antisymmetric soliton complexes exist in the entire parameter space, while the symmetric and asymmetric modes can be found below a critical value of the coupling parameter. Numerical results confirm these predictions. The symmetric complexes are destabilized via a supercritical symmetry-breaking pitchfork bifurcation, which gives rise to stable asymmetric modes. The antisymmetric complexes are subject to oscillatory and exponentially instabilities in narrow parametric regions. In bistability areas, stable antisymmetric solitons coexist with either symmetric or asymmetric ones. Comment: 9 figures

  • Open Access English
    Authors: 
    Sodin, Mikhail;

    We answer negatively to the question posed by Aleksandrov concerning analytic functions of Smirnov's class in the unit disk with pure imaginary boundary values. We also find new sufficient conditions for representations of functions of Smirnov's class by the Schwartz and Cauchy integrals. These conditions extend a previous result of Aleksandrov. 10 pages, to appear in Mat. fizika, analiz, geometriya (Kharkov)

  • Open Access English
    Authors: 
    Rapaport, Ariel;
    Project: EC | FRACTALSANDMETRICNT (306494)

    We show there exists a constant $0

  • Publication . Preprint . Article . 2000
    Open Access English
    Authors: 
    Ormes, Nic; Radin, Charles; Sadun, Lorenzo;
    Project: NSF | Mathematical Sciences: To... (9626698)

    We derive a homeomorphism invariant for those tiling spaces which are made by rather general substitution rules on polygonal tiles, including those tilings, like the pinwheel, which contain tiles in infinitely many orientations. The invariant is a quotient of Cech cohomology, is easily computed directly from the substitution rule, and distinguishes many examples, including most pinwheel-like tiling spaces. We also introduce a module structure on cohomology which is very convenient as well as of intuitive value. 32 pages, including 9 embedded figures

  • Publication . Preprint . 2014
    Open Access English
    Authors: 
    Eliaz, Kfir; Rubinstein, Ariel;
    Project: EC | MODELING TYPOLOGIES (269143)
  • Publication . Article . Preprint . 2019
    Open Access English
    Authors: 
    Dekel Tsur;

    Abstract In the Split to Block Vertex Deletion and Split to Threshold Vertex Deletion problems the input is a split graph G and an integer k, and the goal is to decide whether there is a set S of vertices of size at most k such that G − S is a block graph and G − S is a threshold graph, respectively. In this paper we give algorithms for these problems whose running times are O ⁎ ( 2.076 k ) and O ⁎ ( 1.619 k ) , respectively.

Advanced search in
Research products
arrow_drop_down
Searching FieldsTerms
Any field
arrow_drop_down
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14,864 Research products, page 1 of 1,487
  • Open Access English
    Authors: 
    Ivano Baronchelli; G. Rodighiero; Harry I. Teplitz; Claudia Scarlata; Alberto Franceschini; S. Berta; Laia Barrufet; Mattia Vaccari; Matteo Bonato; Laure Ciesla; +15 more
    Publisher: HAL CCSD
    Countries: France, Italy, United States
    Project: EC | HELP (607254)

    For a sample of star forming galaxies in the redshift interval 0.15$<$z$<$0.3, we study how both the relative strength of the AGN infra-red emission, compared to that due to the star formation (SF), and the numerical fraction of AGNs, change as a function of the total stellar mass of the hosting galaxy group (M$^{*}_{\mathrm{group}}$), between $10^{10.25}$ and $10^{11.9}$M$_{\odot}$. Using a multi-component SED fitting analysis, we separate the contribution of stars, AGN torus and star formation to the total emission at different wavelengths. This technique is applied to a new multi-wavelength data-set in the SIMES field (23 not redundant photometric bands), spanning the wavelength range from the UV (GALEX) to the far-IR (Herschel) and including crucial AKARI and WISE mid-IR observations (4.5 \mu m$<\lambda<$24 \mu m), where the BH thermal emission is stronger. This new photometric catalog, that includes our best photo-z estimates, is released through the NASA/IPAC Infrared Science Archive (IRSA). Groups are identified through a friends of friends algorithm ($\sim$62% purity, $\sim$51% completeness). We identified a total of 45 galaxies requiring an AGN emission component, 35 of which in groups and 10 in the field. We find BHAR$\propto ($M$^{*}_{\mathrm{group}})^{1.21\pm0.27}$ and (BHAR/SFR)$\propto ($M$^{*}_{\mathrm{group}})^{1.04\pm0.24}$ while, in the same range of M$^{*}_{\mathrm{group}}$, we do not observe any sensible change in the numerical fraction of AGNs. Our results indicate that the nuclear activity (i.e. the BHAR and the BHAR/SFR ratio) is enhanced when galaxies are located in more massive and richer groups. Comment: 31 pages, 23 figures

  • Open Access English
    Authors: 
    Golan Miller; Avital Beery; Prashant Kumar Singh; Fengde Wang; Rotem Zelingher; Etel Motenko; Michal Lieberman-Lazarovich;
    Publisher: Oxford University Press
    Country: France

    Abstract Climate change is causing temperature increment in crop production areas worldwide, generating conditions of heat stress that negatively affect crop productivity. Tomato (Solanum lycopersicum), a major vegetable crop, is highly susceptible to conditions of heat stress. When tomato plants are exposed to ambient day/night temperatures that exceed 32 °C/20 °C, respectively, during the reproductive phase, fruit set and fruit weight are reduced, leading to a significant decrease in yield. Processing tomato cultivars are cultivated in open fields, where environmental conditions are not controlled; therefore, plants are exposed to multiple abiotic stresses, including heat stress. Nonetheless, information on stress response in processing tomatoes is very limited. Understanding the physiological response of modern processing tomato cultivars to heat stress may facilitate the development of thermotolerant cultivars. Here, we compared two tomato processing cultivars, H4107 and H9780, that we found to be constantly differing in yield performance. Using field and temperature-controlled greenhouse experiments, we show that the observed difference in yield is attributed to the occurrence of heat stress conditions. In addition, fruit set and seed production were significantly higher in the thermotolerant cultivar H4107, compared with H9780. Despite the general acceptance of pollen viability as a measure of thermotolerance, there was no difference in the percentage of viable pollen between H4107 and H9780 under either of the conditions tested. In addition to observations of similar pollen germination and bud abscission rates, our results suggest that processing tomato cultivars may present a particular case, in which pollen performance is not determining reproductive thermotolerance. Our results also demonstrate the value of combining controlled and uncontrolled experimental settings, in order to validate and identify heat stress-related responses, thus facilitating the development of thermotolerant processing tomato cultivars. Our paper deals with the response of tomato plants to high temperatures. Tomato is an important crop, and tomato plants are very sensitive to high temperatures. Therefore, the increase in temperatures due to climate change poses a threat to tomato production. We found that a specific tomato cultivar is heat stress-tolerant, with better productivity under high temperatures. Usually, such tolerance is linked with pollen grains viability. Interestingly, in our case, pollen characteristics were eliminated as a causal factor for heat stress tolerance, meaning that other factors are involved. Follow-up studies are performed towards the development of heat-tolerant tomato.

  • Open Access English
    Authors: 
    Omer Edhan; Ziv Hellman; Ilan Nehama;
    Publisher: The Royal Society
    Country: United Kingdom

    AbstractWe consider genotypic convergence of populations and show that under fixed fitness asexual and haploid sexual populations attain monomorphic convergence (even under genetic linkage between loci) to basins of attraction with locally exponential convergence rates; the same convergence obtains in single locus diploid sexual reproduction but to polymorphic populations. Furthermore, we show that there is a unified underlying theory underlying these convergences: all of them can be interpreted as instantiations of players in a potential game implementing a multiplicative weights updating algorithm to converge to equilibrium, making use of the Baum–Eagon Theorem. To analyse varying environments, we introduce the concept of ‘virtual convergence’, under which, even if fixation is not attained, the population nevertheless achieves the fitness growth rate it would have had under convergence to an optimal genotype. Virtual convergence is attained by asexual, haploid sexual, and multi-locus diploid reproducing populations, even if environments vary arbitrarily. We also study conditions for true monomorphic convergence in asexually reproducing populations in varying environments.

  • Publication . Article . Preprint . 2017
    Open Access English
    Authors: 
    Kyle Kawagoe; Greg Huber; Marc Pradas; Michael Wilkinson; Alain Pumir; Eli Ben-Naim;

    We investigate statistical properties of trails formed by a random process incorporating aggregation, fragmentation, and diffusion. In this stochastic process, which takes place in one spatial dimension, two neighboring trails may combine to form a larger one and also, one trail may split into two. In addition, trails move diffusively. The model is defined by two parameters which quantify the fragmentation rate and the fragment size. In the long-time limit, the system reaches a steady state, and our focus is the limiting distribution of trail weights. We find that the density of trail weight has power-law tail $P(w) \sim w^{-\gamma}$ for small weight $w$. We obtain the exponent $\gamma$ analytically, and find that it varies continuously with the two model parameters. The exponent $\gamma$ can be positive or negative, so that in one range of parameters small-weight tails are abundant, and in the complementary range, they are rare. Comment: 8 pages, 8 figures

  • Open Access English
    Authors: 
    M. D. Petrović; Goran Gligorić; Aleksandra Maluckov; Lj. Hadžievski; Boris A. Malomed;
    Country: Serbia
    Project: MESTD | Photonics of micro and na... (45010)

    Existence, stability and dynamics of soliton complexes, centered at the site of a single transverse link connecting two parallel 2D (two-dimensional) lattices, are investigated. The system with the on-site cubic self-focusing nonlinearity is modeled by the pair of discrete nonlinear Schr\"{o}dinger equations linearly coupled at the single site. Symmetric, antisymmetric and asymmetric complexes are constructed by means of the variational approximation (VA) and numerical methods. The VA demonstrates that the antisymmetric soliton complexes exist in the entire parameter space, while the symmetric and asymmetric modes can be found below a critical value of the coupling parameter. Numerical results confirm these predictions. The symmetric complexes are destabilized via a supercritical symmetry-breaking pitchfork bifurcation, which gives rise to stable asymmetric modes. The antisymmetric complexes are subject to oscillatory and exponentially instabilities in narrow parametric regions. In bistability areas, stable antisymmetric solitons coexist with either symmetric or asymmetric ones. Comment: 9 figures

  • Open Access English
    Authors: 
    Sodin, Mikhail;

    We answer negatively to the question posed by Aleksandrov concerning analytic functions of Smirnov's class in the unit disk with pure imaginary boundary values. We also find new sufficient conditions for representations of functions of Smirnov's class by the Schwartz and Cauchy integrals. These conditions extend a previous result of Aleksandrov. 10 pages, to appear in Mat. fizika, analiz, geometriya (Kharkov)

  • Open Access English
    Authors: 
    Rapaport, Ariel;
    Project: EC | FRACTALSANDMETRICNT (306494)

    We show there exists a constant $0

  • Publication . Preprint . Article . 2000
    Open Access English
    Authors: 
    Ormes, Nic; Radin, Charles; Sadun, Lorenzo;
    Project: NSF | Mathematical Sciences: To... (9626698)

    We derive a homeomorphism invariant for those tiling spaces which are made by rather general substitution rules on polygonal tiles, including those tilings, like the pinwheel, which contain tiles in infinitely many orientations. The invariant is a quotient of Cech cohomology, is easily computed directly from the substitution rule, and distinguishes many examples, including most pinwheel-like tiling spaces. We also introduce a module structure on cohomology which is very convenient as well as of intuitive value. 32 pages, including 9 embedded figures

  • Publication . Preprint . 2014
    Open Access English
    Authors: 
    Eliaz, Kfir; Rubinstein, Ariel;
    Project: EC | MODELING TYPOLOGIES (269143)
  • Publication . Article . Preprint . 2019
    Open Access English
    Authors: 
    Dekel Tsur;

    Abstract In the Split to Block Vertex Deletion and Split to Threshold Vertex Deletion problems the input is a split graph G and an integer k, and the goal is to decide whether there is a set S of vertices of size at most k such that G − S is a block graph and G − S is a threshold graph, respectively. In this paper we give algorithms for these problems whose running times are O ⁎ ( 2.076 k ) and O ⁎ ( 1.619 k ) , respectively.

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