Moment equations in a Lotka-Volterra extended system with time correlated noise

A spatially extended Lotka-Volterra system of two competing species in the presence of two correlated noise sources is analyzed: (i) an external multiplicative time correlated noise, which mimics the interaction between the system and the environment; (ii) a dichotomous stochastic process, whose jump rate is a periodic function, which represents the interaction parameter between the species. The moment equations for the species densities are derived in Gaussian approximation, using a mean field approach. Within this formalism we study the effect of the external time correlated noise on the ecosystem dynamics. We find that the time behavior of the $1^{st}$ order moments are independent on the multiplicative noise source. However the behavior of the $2^{nd}$ order moments is strongly affected both by the intensity and the correlation time of the multiplicative noise. Finally we compare our results with those obtained studying the system dynamics by a coupled map lattice model.Comment: 12 pages, 7 figures, to appear in Acta Phys. Pol.

Variational solution of the Gross-Neveu model; 2, finite-N and renormalization

We show how to perform systematically improvable variational calculations in the O(2N) Gross-Neveu model for generic N, in such a way that all infinities usually plaguing such calculations are accounted for in a way compatible with the renormalization group. The final point is a general framework for the calculation of non-perturbative quantities like condensates, masses, etc..., in an asymptotically free field theory. For the Gross-Neveu model, the numerical results obtained from a "two-loop" variational calculation are in very good agreement with exact quantities down to low values of N

DC conduction mechanism of some new lower rim substituted calixarenes derivatives in thin films

Date du colloque : 09/2014International audienc

The Arabidopsis thaliana-Alternaria brassicicola pathosystem: A model interaction for investigating seed transmission of necrotrophic fungi

Seed transmission constitutes a major component of the parasitic cycle for several fungal pathogens. However, very little is known concerning fungal or plant genetic factors that impact seed transmission and mechanisms underlying this key biological trait have yet to be clarified. Such lack of available data could be probably explained by the absence of suitable model pathosystem to study plant-fungus interactions during the plant reproductive phase

Genome sequence of the necrotrophic plant pathogen Alternaria brassicicola Abra43

Alternaria brassicicola causes dark spot (or black spot) disease, which is one of the most common and destructive fungal diseases of Brassicaceae spp. worldwide. Here, we report the draft genome sequence of strain Abra43. The assembly comprises 29 scaffolds, with an N50 value of 2.1 Mb. The assembled genome was 31,036,461 bp in length, with a G+C content of 50.85%

Przeciwgrzybiczne działanie niektórych wyciągów roślinnych przeciwko Alternaria alternata (Fr.) Keissl. u czarnej porzeczki (Ribes nigrum L.)

There were tested and screened, in vitro and in vivo, for the first time in Romania, nine respectively six plant extracts manufactured by Hofigal S.A. against Alternaria alternata (strain Aa 20) isolated from blackcurrant (Ribes nigrum L.). The highest in vitro activity (efficacy between 70% and 100%) was recorded for Satureja hortensis and Valeriana officinalis extracts at 20 and 10% concentrations. A good inhibitory activity on mycelial growth (efficacy between 54.3 and 88.6%) has been noticed for Allium sativum, Mentha sp. Rosmarinus officinalis, Tagetes patula extracts (at 10 and 20%). No efficacy was noticed for Artemisia dracunculus ‘sativa’. The extract obtained from Hyssopus officinalis inhibited the mycelial growth of A. alternata only at 20%, with 57.1% efficacy. In field trials, Valeriana officinalis and Satureja hortensis extracts have been very effective in limiting Alternaria disease severity in blackcurrant applied at 10%, compared to untreated control. This data confirmed their strong antifungal potential, both in vitro and in vivo. Based on our results, plant extracts with highly efficacy could be an alternative in the protection of blackcurrant as medicinal crop against Alternaria leaf spot and fruit rot especially in organic horticulture system.Po raz pierwszy w Rumunii przetestowano i zbadano in vitro i in vivo odpowiednio dziewięć i sześć wyciągów wyprodukowanych przez Hofigal S.A. w ich działaniu przeciwko Alternaria alternata (szczep Aa 20) wyizolowanego z czarnej porzeczki (Ribes nigrum L.). Najlepsze działanie in vivo (skuteczność między 70–100%) zanotowano dla Satureja hortensis i Valeriana officinalis. Dobre działanie inhibicyjne wobec wzrostu grzybni (skuteczność między 54,3–88,6%) zaobserwowano dla Allium sativum, Mentha sp. Rosmarinus officinalis, Tagetes patula (10 i 20%). Nie stwierdzono żadnej skuteczności dla Artemisia dracunculus ‘sativa’. Wyciąg otrzymany z Hyssopus officinalis hamował wzrost grzybni A. alternata tylko przy 20% ze skutecznością 57.1%. W próbach polowych wyciągi z Valeriana officinalis i Satureja hortensis były bardzo skuteczne, ograniczając chorobę Alternaria u czarnej porzeczki przy 10% w porównaniu z kontrolą bez zabiegów. Dane te potwierdziły ich silny potencjał przeciwgrzybiczy zarówno in vitro, jak i in vivo. Opierając się na niniejszych wynikach, można powiedzieć, że wyciągi roślinne o wysokiej skuteczności mogą być alternatywą w ochronie czarnej porzeczki jako rośliny leczniczej przed plamistością liści i zgnilizną owoców spowodowanych przez Alternaria, zwłaszcza w ekologicznym systemie upraw ogrodniczych

Grzybobójcze działanie niektórych wyciągów roślinnych przeciw Botrytis cinerea Pers. w plonie czarnej porzeczki (Ribes nigrum L.)

There were tested and screened, in vitro and in vivo, for the first time in Romania, nine respectively six plant extracts manufactured by Hofigal S.A. against Botrytis cinerea (strain Bc 27) isolated from blackcurrant (Ribes nigrum L.). The highest antibotrytis in vitro activity (efficiency between 80 and 100%) was obtained using the following extracts: Hyssopus officinalis (at 20, 10 and 5%), Satureja hortensis, Allium sativum, Tagetes patula (at 20 and 10%) and Mentha (at 20%). A moderate antibotrytis activity (efficiency between 35.7 and 65.7%) has been noticed for Mentha (at 10 and 5%), Satureja hortensis, Allium sativum and Tagetes patula (at 5%) extracts. The lowest antibotrytis activity or no efficiency was noticed using extracts obtained from Achillea millefolium, Artemisia dracunculus ‘sativa’, Rosmarinus officinalis and Valeriana officinalis even applied at 20%. Based on results obtained in in vitro tests, six plant extracts were tested and screened in vivo, under field conditions at Hofigal S.A. Bucharest. Satureja hortensis, Allium sativum, Hyssopus officinalis, Menthaand Tagetes patula extracts have been efficient in limiting gray mold severity in blackcurrant applied at 10% compared to untreated control. No in vivo activity was registered for Valeriana officinalis extract. Plant extracts with highly efficiency can be recommended as a non-polluting and environmental-friendly alternative (organic horticulture) in the protection of blackcurrant as medicinal crop against grey mould, the most economically important disease in Europe at present.Po raz pierwszy w Rumunii przetestowano i dokonano przesiewu in vitro oraz in vivo dziewięciu wyciągów roślinnych produkowanych przez Hofigal S.A. przeciwko Botrytis cinerea (szczep Bc 27) wyizolowanego z czarnej porzeczki (Ribes nigrum L.). Najlepszy efekt przeciw Botrytis in vitro (wydajność między 80 a 100%) uzyskano przy użyciu następujących wyciągów: Hyssopus officinalis (przy 20, 10 i 5%), Satureja hortensis, Allium sativum, Tagetes patula (przy 20 i 10%) oraz Mentha sp. (przy 20%). Umiarkowany efekt przeciw Botrytis (wydajność między 35,7 a 65,7%) zaobserwowano dla wyciągów Mentha sp. (przy 10 i 5%), Satureja hortensis, Allium sativum and Tagetes patula (przy 5%). Najsáabszy efekt przeciw Botrytis lub zero efektu stwierdzono przy użyciu wyciągów otrzymanych z Achillea millefolium, Artemisia dracunculus ‘Sativa’, Rosmarinus officinalis i Valeriana officinalis, zastosowanych nawet w 20%. Na podstawie wyników otrzymanych in vitro przetestowano i dokonano przesiewu in vivo sześciu wyciągów roślinnych w warunkach polowych w Hofigal S.A. Bucharest. Wyciągi Satureja hortensis, Allium sativum, Hyssopus officinalis, Mentha sp. i Tagetes patula byáy skuteczne przy 10% w ograniczaniu nasilenia szarej pleśni w porzeczce w porównaniu z kontrolą. Nie zarejestrowano żadnego dziaáania in vivo dla wyciągu Valeriana officinalis. Wyciągi roślinne o dużej skuteczności mogą być rekomendowane jako alternatywne środki przyjazne dla środowiska, niepowodująca zanieczyszczenia (ogrodnictwo organiczne) w ochronie czarnej porzeczki jako rośliny leczniczej przeciwko szarej pleśni, która jest obecnie gospodarczo najważniejszą chorobą w Europie

In vitro antifungal activity of some plant extracts against Fusarium oxysporum in blackcurrant (Ribes nigrum L.)

There were tested and screened, in vitro, nine plant extracts manufactured by Hofigal S.A., against Fusarium oxysporum (strain Fo 18) isolated from blackcurrant plants (Ribes nigrum L.). The highest in vitro activity (efficacy 78.6%) was recorded for Allium sativum extract, followed by Satureja hortensis and Valeriana officinalis extracts (71.4% efficacy), at 20% concentration. A good inhibitory activity on mycelial growth has been observed for Mentha sp., Rosmarinus officinalis, Hyssopus officinalis and Artemisia dracunculus ‘Sativa’ (62.8%, 58.6%, 57.1% and, respectively, 50% efficacy). Achillea millefolium extract had no effect on radial growth of F. oxysporum isolate. This report is the first in Romania regarding the in vitro antifungal activity of some plant extracts on F. oxysporum in blackcurrant. These data are very useful for plant protection practice, particularly for medicinal plants, as blackcurrant, which demands for non pollutant and environmental friendly alternative methods to fungicides. Locally plant extracts could have important roles in sustainable based management strategies of Fusarium disease in blackcurrant

Electron spin resonance spectroscopy investigations of carbon nanotubes - epoxy composites

Electron spin resonance investigations on carbon nanotubes-epoxy composites containing 1%, 2%, and 3% multiwalled nanotubes with a length of 10 pm are reported. The observed resonance spectrum is dominated by a strong line with a peak to peak width of about 14 Gauss, located at g=2.023, and characterized by a negligible asymmetry. It was found that the resonance line position (g factor), resonance line width, and double integral of the resonance line are essentially temperature independent in the range 150 K - 250 K. This resonance line was assigned to uncoupled electronic spins delocalized over carbon nanotubes