485 research outputs found
Ecological study of aquatic midges and some related insects with special reference to feeding habits
Die Schweiz ist ein reiches Land. Sie verfĂŒgt ĂŒber viele MillionĂ€re. Der groĂe Reichtum konzentriert sich auf wenige Familien und Personen. In der Schweiz leben aber auch eine halbe Million der Bevölkerung (7,5 Mio.) in Haushalten von ErwerbstĂ€tigen, die weniger als das Existenzminimum verdienen. Ăber 200â000 Personen sind auf Sozialhilfe angewiesen. Bei den Vermögen und den verfĂŒgbaren Einkommen hat sich in den letzten Jahren die Kluft zwischen den obersten und untersten zehn Prozent verschĂ€rft. Die Zunahme der sozialen Ungleichheit erhöht die soziale Brisanz, was mehr zu ergrĂŒnden ist. Die soziale Differenzierung dokumentiert Prozesse der Globalisierung. Sie reproduziert und spezifiziert alte soziale Ungleichheiten. Wichtig ist, dass die Soziale Arbeit das thematisiert und weiter theoretisiert
Soil amendment with activated charcoal can reduce dieldrin uptake by cucumbers
Organochlorine pesticides (OCP) were once applied world wide but have been banned meanwhile in most countries because of their ecotoxicity, bioaccumulation and persistence. However, residues can still be present in soils even many years after applications have been stopped and taken up by crop plants. OCP accumulation from bound residues was found to be a particular problem in Cucurbitaceae plants. Two soil surveys performed in 2002 and 2005 in Switzerland revealed that OCP residues were taken up by cucumbers grown in soils that have been converted to organic production in the meantime. Even if legal tolerance values are not exceeded, this is a serious economic problem for the farmers affected by contaminated crops, because consumers of organically grown crops are only willing to pay the higher prices for these than for conventional products because they are particularly concerned about health and environmental quality and therefore expect pristine food. One approach to address the problem would be to increase the capacity of affected soils to bind OCP residues in order to prevent their uptake by the crops. In this study, we wanted to test the potential use of activated charcoal (AC) for this purpose. In addition, we wanted to assess the possibility of using OCP sorption in soil by TenaxÂź beads as a predictor for the phytoavailability of these compounds to cucumbers.
We performed two pot experiments in which the cash crop cucumber (Cucumis sativus L.) was grown in soil with bound residues of dieldrin (70 ”g/kg), pentachloroaniline (<0.01 ”g/kg) and p,p-DDE. The soil was taken from a field under organic farming in which these residues were found in the 2005 survey. In the first experiment, cucumbers were grown for 12 to 13 weeks (until fruits were ripe) in soil into which AC had been mixed at concentrations of 200, 400, and 800 mg/kg and in untreated controls. In the second experiment, TenaxŸ beads were added to the soil and cucumbers, grown with and without AC amendment (800 mg/kg soil), were harvested after 4, 8, 10, 11, 12, and 13 weeks.
Dieldrin was the only pesticide detected in the sampled cucumbers and extracted from soil by the Tenax beads. Dieldrin concentrations in the cucumbers were significantly reduced in the treatments with 400 and 800 mg/kg AC. Also significantly less dieldrin was sorbed by Tenax from the soil amended with 800 mg/kg AC than from the untreated control soil. More dieldrin was found to be sorbed by Tenax in the last 3-4 weeks of the experiment, particularly in the control soil, but this trend was not significant. The correlation between the amounts of Tenax-sorbed dieldrin and dieldrin accumulation in the cucumber fruits was significant in control soil and 800 mg/kg AC soil. Hence, Tenax appeared to be suited for the assessment of dieldrin solubility in soil and of phytoavailability to cucumbers
Gesunder Boden - gesunde Pflanzen
Obwohl viele Ă€ltere Biobetriebe kleinere NĂ€hrstoffgehalte im Boden aufwiesen, waren diese noch nicht ertragsbegrenzend. Die abnehmenden NĂ€hrstoffgehalte im Boden und den Pflanzen zeigen, dass regelmĂ€ssige Bodenanalysen auf dem Biobetrieb nötig sind. Die SuppressivitĂ€t der Böden hing nicht direkt von den Biojahren ab. Durch die Gestaltung der Fruchtfolge und den HofdĂŒngereinsatz lĂ€sst sie sich aber steigern. Der Zusammenhang zwischen Bewirtschaftung Bodeneigenschaften und der SuppressivitĂ€t muss genauer untersucht werden
Electronic structure of intentionally disordered AlAs/GaAs superlattices
We use realistic pseudopotentials and a plane-wave basis to study the
electronic structure of non-periodic, three-dimensional, 2000-atom
(AlAs)_n/(GaAs)_m (001) superlattices, where the individual layer thicknesses
n,m = {1,2,3} are randomly selected. We find that while the band gap of the
equivalent (n = m = 2) ordered superlattice is indirect, random fluctuations in
layer thicknesses lead to a direct gap in the planar Brillouin zone, strong
wavefunction localization along the growth direction, short radiative
lifetimes, and a significant band-gap reduction, in agreement with experiments
on such intentionally grown disordered superlattices.Comment: 10 pages, REVTeX and EPSF macros, 4 figures in postscript. e-mail to
[email protected]
Kurzfristige und langfristige Auswirkungen von zwei Spritzfolgen im Kartoffelbau auf biologische Parameter der Bodenfruchtbarkeit
Die ToxizitÀt eines Pflanzenschutzmittels (PSM)wird anhand von Untersuchungen der Herstellerfirmen ermittelt und beruht in der Regel auf der Wirkung eines einzelnen Wirkstoffes oder Produktes auf einen definierten Indikator-Organismus. In der landwirtschaftlichen Praxis werden die Wirkstoffe jedoch hÀufig in Kombination mit anderen Mitteln oder in rascher Abfolge ausgebracht. Zu den kumulativen Wirkungen von Pestiziden, wie sie in einer Kultur angewendet werden, gibt es bislang nur vereinzelte Untersuchungen (Bromilov et al. 1996; Moorman, 1989; Nicholson und Hirsch, 1998; Schuster und Schröder, 1990).
In diesem Bericht werden die Ergebnisse aus einem Modellversuch ĂŒber die kurz- und langfristigen Auswirkungen von PSM in der Kartoffelkultur auf die Bodenmikroorganismen dargestellt.
Ergebnisse: Die verabreichten Pestizide ĂŒbten einen signifikanten Einfluss auf die mikrobielle Biomasse, AktivitĂ€t und DiversitĂ€t aus. Die kurzfristigen Auswirkungen der Kartoffelspritzfolge waren bei fast allen erhobenen bodenbiologischen Parametern signifikant. Das in der Schweiz bis 2001 unter den zwanzig meist angewendeten Wirkstoffen, aber inzwischen vom Markt gezogene, PSM Dinoseb hatte eine erheblich stĂ€rkere Nebenwirkung auf die Bodenlebewesen. Die meisten Parameter erholten sich weitgehend bis zur zweiten Probenahme (135 Tage nach der letzten Spritzung) mit Ausnahme der Substratnutzungsmuster und der Algenpopulation, die im Rahmen von sukzessionalen Effekten Unterschiede zwischen den Verfahren anzeigten. Die hier vorgestellten Ergebnisse beruhen auf Modellversuchen. Es stellt sich die Frage, welche Effekte die PSM im Feld haben. Um diese Frage zu beantworten, wurde 2002 ein Feldversuch angelegt, in welchem die Wirkung von PSM auf die Bodenlebewesen in einer Fruchtfolge untersucht wird
Deep security analysis of program code: a systematic literature review
Due to the continuous digitalization of our society, distributed and web-based applications become omnipresent and making them more secure gains paramount relevance. Deep learning (DL) and its representation learning approach are increasingly been proposed for program code analysis potentially providing a powerful means in making software systems less vulnerable. This systematic literature review (SLR) is aiming for a thorough analysis and comparison of 32 primary studies on DL-based vulnerability analysis of program code. We found a rich variety of proposed analysis approaches, code embeddings and network topologies. We discuss these techniques and alternatives in detail. By compiling commonalities and differences in the approaches, we identify the current state of research in this area and discuss future directions. We also provide an overview of publicly available datasets in order to foster a stronger benchmarking of approaches. This SLR provides an overview and starting point for researchers interested in deep vulnerability analysis on program code
Mycorrhizal fungi as natural bio-fertilizers: How to produce and use
This technical handbook provides an easy to follow guide describing the process on how to produce home-made mycorrhizal inoculants using different types of propagation units and how inoculants can be applied as bio-fertilizers in the nursery and during field transplantation for improving the growth and stress tolerance of crop plants
The performance of yields in organic and conventional cropping systems
Sufficient and stable crop yields are the basis for feeding a growing world population. Limited cropland, climate change, loss of soil quality and biodiversity coupled with excessive use of non-renewable resources require new solutions for future cropping systems beyond existing management practices. Here we compare the yield performance of organic and conventional cropping systems
Correlation of conductivity and angle integrated valence band photoemission characteristics in single crystal iron perovskites for 300 K < T < 800 K: Comparison of surface and bulk sensitive methods
A single crystal monolith of La0.9Sr0.1FeO3 and thin pulsed laser deposited
film of La0.8Sr0.2Fe0.8Ni0.2O3 were subject to angle integrated valence band
photoemission spectroscopy in ultra high vacuum and conductivity experiments in
ambient air at temperatures from 300 K to 800 K. Except for several sputtering
and annealing cycles, the specimen were not prepared in-situ.. Peculiar changes
in the temperature dependent, bulk representative conductivity profile as a
result of reversible phase transitions, and irreversible chemical changes are
semi-quantitatively reflected by the intensity variation in the more surface
representative valence band spectra near the Fermi energy. X-ray photoelectron
diffraction images reflect the symmetry as expected from bulk iron perovskites.
The correlation of spectral details in the valence band photoemission spectra
(VB PES) and details of the conductivity during temperature variation suggest
that valuable information on electronic structure and transport properties of
complex materials may be obtained without in-situ preparation
Vascular Injury After Whole Thoracic X-Ray Irradiation in the Rat
Purpose To study vascular injury after whole thoracic irradiation with single sublethal doses of X-rays in the rat and to develop markers that might predict the severity of injury. Methods and Materials Rats that received 5- or 10-Gy thorax-only irradiation and age-matched controls were studied at 3 days, 2 weeks, and 1, 2, 5, and 12 months. Several pulmonary vascular parameters were evaluated, including hemodynamics, vessel density, total lung angiotensin-converting enzyme activity, and right ventricular hypertrophy. Results By 1 month, the rats in the 10-Gy group had pulmonary vascular dropout, right ventricular hypertrophy, increased pulmonary vascular resistance, increased dry lung weights, and decreases in total lung angiotensin-converting enzyme activity, as well as pulmonary artery distensibility. In contrast, irradiation with 5 Gy resulted in only a modest increase in right ventricular weight and a reduction in lung angiotensin-converting enzyme activity. Conclusion In a previous investigation using the same model, we observed that recovery from radiation-induced attenuation of pulmonary vascular reactivity occurred. In the present study, we report that deterioration results in several vascular parameters for â€1 year after 10 Gy, suggesting sustained remodeling of the pulmonary vasculature. Our data support clinically relevant injuries that appear in a time- and dose-related manner after exposure to relatively low radiation doses
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