334 research outputs found
Source apportionment of carbonaceous chemical species to fossil fuel combustion, biomass burning and biogenic emissions by a coupled radiocarbon-levoglucosan marker method
An intensive aerosol measurement and sample collection campaign was conducted in central Budapest in a mild winter for 2 weeks. The online instruments included an FDMS-TEOM, RT-OC/EC analyser, DMPS, gas pollutant analysers and meteorological sensors. The aerosol samples were collected on quartz fibre filters by a low-volume sampler using the tandem filter method. Elemental carbon (EC), organic carbon (OC), levoglucosan, mannosan, galactosan, arabitol and mannitol were determined, and radiocarbon analysis was performed on the aerosol samples. Median atmospheric concentrations of EC, OC and PM2.5 mass were 0.97, 4.9 and 25 mu g m(-3), respectively. The EC and organic matter (1.6 x OC) accounted for 4.8 and 37 %, respectively, of the PM2.5 mass. Fossil fuel (FF) combustion represented 36% of the total carbon (TC = EC + OC) in the PM2.5 size fraction. Biomass burning (BB) was a major source (40 %) for the OC in the PM2.5 size fraction, and a substantial source (11 %) for the PM10 mass. We propose and apply here a novel, straightforward, coupled radiocarbon-levoglucosan marker method for source apportionment of the major carbonaceous chemical species. The contributions of EC and OC from FF combustion (ECFF and OCFF to the TC were 11.0 and 25 %, respectively, EC and OC from BB (ECBB and OCBB were responsible for 5.8 and 34 %, respectively, of the TC, while the OC from biogenic sources (OCBIO made up 24% of the TC. The overall relative uncertainty of the OCBIO and OCBB contributions was assessed to be up to 30 %, while the relative uncertainty for the other apportioned species is expected to be below 20 %. Evaluation of the apportioned atmospheric concentrations revealed some of their important properties and relationships among them. ECFF and OCFF were associated with different FF combustion sources. Most ECFF was emitted by vehicular road traffic, while the contribution of non-vehicular sources such as domestic and industrial heating or cooking using gas, oil or coal to OCFF was substantial. The mean contribution of BB to EC particles was smaller by a factor of approximately 2 than that of road traffic. The main formation processes of OCFF, OCBB and OCBIO from volatile organic compounds were jointly influenced by a common factor, which is most likely the atmospheric photochemistry, while primary organic emissions can also be important. Technological improvements and control measures for various BB appliances, together with efficient education and training of their users, in particular on the admissible fuel types, offer an important potential for improving the air quality in Budapest, and likely in other cities as well
Occurrence of Grey Mould on Bucida buceras, a Tree of Subtropical Origin, under Indoor Conditions - A Disease Note
In December 2012 then in the following winter season, the occurrence of whitish mycelial coat was observed on the collar of 3- to 6-m high Bucida buceras trees grown in hydrocultures to decorate a spacious indoor community space in Vienna. (This plant [shown in Fig. 1] belongs to Combretaceae, Myrtales and commonly named black olive tree, bullet tree, gregorywood and oxhorn bucida.) The mycelium-infested area of the bark appeared to be water-soaked. Near the surface of the potting mix (earth ball embedded in clay pebbles), the roots were also covered with whitish mycelia (Fig. 2). Over the winter season when the indoor temperature increased from 20 °C to 25 °C, these symptoms were unnoticeable. Regardless of the season, the rhizosphere contained numbers of sclerotia, dark-grey, globose and 8â12 mm in diameter that occasionally developed rhizomorph-like mycelial cords.
Direct plating of mycelium fragments from the bark and sclerotia from the rhizosphere onto potato dextrose agar amended with ampicillin (500 mg/l) eventually yielded pure fungal cultures of similar characteristics. Cultures routinely incubated in the dark developed white and submerged colonies with sparse aerial mycelia. The fungus grew well between 10 °C and 25 °C, and failed to grow at either 5 °C or 32 °C. The optimal growth was measured at 20 °C with an average radial growth rate of 11 mm per day. After 10 to 12 days, a ring of sclerotia begun to develop near the edge of the colonies; they turned dark grey and sized 3â8 mm. Rather misleadingly, neither conidia, nor sexual spores were observed in these cultures. However, when the fungus was cultured in natural light under laboratory conditions at 25 °C, a completely different colony pattern was observed; it was cottony, greyish then dark grey, and produced abundant hyaline conidia borne on grey, branching tree-like conidiophores. Conidia were one-celled and egg-shaped, and their dimensions fell in the range of 9.89â14.63 (11.48±0.31) ”mĂ7.05â10.05 (8.31±0.20) ”m. These features concurred with those characterising the polyphagous grey mould fungus Botryotinia fuckeliana (anamorph: Botrytis cinerea) (Elad et al., 2007). The ITS1/ITS2 including the 5.8S subunit of rDNA of one of the isolates were amplified with primers ITS1-F/ITS4, then the PCR products were sequenced. The ITS sequence determined in this way was identical to known sequences of B. fuckeliana strains, e.g. that of CBS 131.28 (GenBank accession number: KF859918), the type material of Botrytis cinerea f. lini, DAOM 231372 (GenBank accession number: KF859924) and so on.
Pathogenicity tests resulted in rapidly (within 2 weeks) developing disease symptoms around the site of wound inoculation with a 5-mm-diametre mycelial agar plug: fruit rot on apple and lemon in the laboratory, and sunken lesions on stems of hydrocultured ornamental plants such as the herbaceous Monstera deliciosa and the woody Dracena marginata. To fulfill Kochâs postulates, the fungus was re-isolated from symptomatic apple fruit, and was found to exhibit the afore-mentioned morpho-physiological characteristics.
Inoculation test on Bucida was not performed because of the costly risk i.e., the sale price of the trees is ⏠3 to 10 thousand. Consequently, the actual sensitivity of Bucida to grey mould remains uncertain, so much the more because this plant species has not been recorded as a host of the pathogen or other important parasitic fungi in natural (subtropical) environment (e.g. Whelburg et al., 1975). To our knowledge, this report is the first description of Botryotinia fuckeliana on Bucida buceras. In addition to the fact that periodic emergence of fungal mycelia on the trunk impairs the treeâs aesthetic appearance, the sclerotia resting in the potting mix may cause more serious problems in the long term. However, it cannot be precluded that the elevated indoor temperature reduces disease progression and thus the economic importance of the pathogen on this plant
Comparison of averages of flows and maps
It is shown that in transient chaos there is no direct relation between
averages in a continuos time dynamical system (flow) and averages using the
analogous discrete system defined by the corresponding Poincare map. In
contrast to permanent chaos, results obtained from the Poincare map can even be
qualitatively incorrect. The reason is that the return time between
intersections on the Poincare surface becomes relevant. However, after
introducing a true-time Poincare map, quantities known from the usual Poincare
map, such as conditionally invariant measure and natural measure, can be
generalized to this case. Escape rates and averages, e.g. Liapunov exponents
and drifts can be determined correctly using these novel measures. Significant
differences become evident when we compare with results obtained from the usual
Poincare map.Comment: 4 pages in Revtex with 2 included postscript figures, submitted to
Phys. Rev.
Diffusion in normal and critical transient chaos
In this paper we investigate deterministic diffusion in systems which are
spatially extended in certain directions but are restricted in size and open in
other directions, consequently particles can escape. We introduce besides the
diffusion coefficient D on the chaotic repeller a coefficient which
measures the broadening of the distribution of trajectories during the
transient chaotic motion. Both coefficients are explicitly computed for
one-dimensional models, and they are found to be different in most cases. We
show furthermore that a jump develops in both of the coefficients for most of
the initial distributions when we approach the critical borderline where the
escape rate equals the Liapunov exponent of a periodic orbit.Comment: 4 pages Revtex file in twocolumn format with 2 included postscript
figure
Susceptibility of European pear genotypes in a gene bank to pear psylla damage and possible exploitation of resistant varieties in organic farming
We evaluated 285 pear genotypes (commercial cultivars, ancient local varieties, unnamed local strains, seedlings, wild seedlings) in the largest gene bank of pear in Hungary from the point of view of psylla resistance to explore their possible exploitation in organic farming. We have found some 10 new resistant types (BĂłkolĂł körte, BĂŽtermĂŽ KĂĄlmĂĄn, FĂŒge alakĂș körte, Nagyasszony körte, NyĂĄri KĂĄlmĂĄn, Rozs nyĂĄri körte, Viki körte, Pb-242, Pb-299, 0-632) and 7 highly tolerant ones (Cure-6, KĂ©sei KĂĄlmĂĄn, Kieffer, Kieffer Ăd, Steiner, TĂ©li KĂĄlmĂĄn, II. B-3- 6/4, 96-16/5) (Table 1). These made up 3.5 + 2.8 per cent of the investigated genotypes, while 93.7 per cent of them were susceptible to pear psylla damage. Taking earlier and present results into account we can list more than 30 European pear cultivars being resistant or highly tolerant to pear psylla infestation and damage. In fact, the list of resistant and highly tolerant cultivars may serve as a basis selecting pear cultivars fitting to the specific requirements of the organic farming. By the end we can conclude that there is some real hope to exploit some resistant or highly tolerant ancient or local cultivars in organic farming but further investigations are needed to estimate their yield capacity and fruit quality
Susceptibility of European pear genotypes in a gene bank to pear psylla damage and possible exploitation of resistant varieties in organic farming
We evaluated 285 pear genotypes (commercial cultivars, ancient local varieties, unnamed local strains, seedlings, wild seedlings) inthe largest gene bank of pear in Hungary from the point of view of psylla resistance to explore their possible exploitation in organic farming.We have found some 10 new resistant types (BĂłkolĂł körte, BĂŽtermĂŽ KĂĄlmĂĄn, FĂŒge alakĂș körte, Nagyasszony körte, NyĂĄri KĂĄlmĂĄn, Rozs nyĂĄrikörte, Viki körte, Pb-242, Pb-299, 0-632) and 7 highly tolerant ones (Cure-6, KĂ©sei KĂĄlmĂĄn, Kieffer, Kieffer Ăd, Steiner, TĂ©li KĂĄlmĂĄn, II. B-3-6/4, 96-16/5) (Table 1). These made up 3.5 + 2.8 per cent of the investigated genotypes, while 93.7 per cent of them were susceptible to pearpsylla damage. Taking earlier and present results into account we can list more than 30 European pear cultivars being resistant or highly tolerantto pear psylla infestation and damage. In fact, the list of resistant and highly tolerant cultivars may serve as a basis selecting pear cultivars fittingto the specific requirements of the organic farming. By the end we can conclude that there is some real hope to exploit some resistant or highlytolerant ancient or local cultivars in organic farming but further investigations are needed to estimate their yield capacity and fruit quality
Topological Defects in Nematic Droplets of Hard Spherocylinders
Using computer simulations we investigate the microscopic structure of the
singular director field within a nematic droplet. As a theoretical model for
nematic liquid crystals we take hard spherocylinders. To induce an overall
topological charge, the particles are either confined to a two-dimensional
circular cavity with homeotropic boundary or to the surface of a
three-dimensional sphere. Both systems exhibit half-integer topological point
defects. The isotropic defect core has a radius of the order of one particle
length and is surrounded by free-standing density oscillations. The effective
interaction between two defects is investigated. All results should be
experimentally observable in thin sheets of colloidal liquid crystals.Comment: 13 pages, 16 figures, Phys. Rev.
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