Urban Organic Farming in Austria with the concept of Selbsternte ("self -harvest"): An agronomic and socio-economic analysis

In Vienna, consultants, organic farmers and green-minded consumers have developed a new concept of urban organic farming, called Selbsternte (`self-harvest'). Organic farmers prepare a plot of arable land (the Selbsternte plot) and sow or plant rows composed of 18-23 plant species. In mid-May the plots are divided into subplots that contain 2-6m of every sown species and are rented to so-called self-harvesters for a period of about 136 days. In 2002 Selbsternte was being practiced at 15 plots in Vienna or in neighboring cities, represented by 861 subplots, with a total area of 68,740m2, and managed by 12 organic farmers for 861 registered self-harvesters. At the Roter Berg plot, experimental subplots were established to evaluate yields and the value of the harvested produce, and interviews were conducted with 27 self-harvesters, the eight Selbsternte farmers and one Selbsternte consultant. The experimental subplots were managed in two different ways, namely, `with low intensity' (LIS) and `with high intensity' (HIS; meaning additional harrowing, mulching and sowing of additional plants). At the LIS 24.2 h and at the HIS 38.9 h of work were invested over 51 days. Monetary investment was US$184 for the LIS and US$259 for the HIS subplots. The total harvest of fresh produce was: 163 kg/subplot for LIS and 208 kg/subplot for HIS subplots. The total value of the harvest at the HIS was US$364 for conventional and US$766 for organic prices. All self- arvesters saw the rental of a subplot and the work as an activity of leisure. More than half of the self-harvesters reported `trying something new' at their subplots. The most frequently mentioned innovation for them was growing an unknown species. Twenty-five self-harvesters sowed 54 different, additional plant species. The motivating factors in establishing Selbsternte plots, as reported by all the farmers, were, primarily, better relations with consumers and work diversifcation, and only then were economic factors a consideration. The contribution of Selbsternte to income varied at the farms, being between 0 and 30% of the total farm income. As a main success factor, all of the farmers reported a close relationship between the self-harvesters and the farmers. Selbsternte subplots can be understood as small experimental stations where self-harvesters merge traditional horticultural techniques with urban ideas on permaculture, sustainable land use and participatory farming. Selbsternte has potential value for the improvement of urban agriculture, but also for the development of organic farming in general

New Analytical Approach for Computation of Band Structure in One-dimensional Periodic Media

In this paper, we present a new approach for the exact calculation of band structure in one-dimensional periodic media, such as photonic crystals and superlattices, based on the recently reported differential transfer matrix method (DTMM). The media analyzed in this paper can have arbitrary profile of refractive index. We derive a closed form dispersion equation using differential transfer matrix formalism, and simplify it under the assumptions of even symmetry and real-valued wavenumber. We also show that under normal incidence both TE and TM modes must have the same band structure. Several numerical test cases are also studied and discussed

Efficiënte keten: Preventie van reststromen: Rapportage 2017/2018

Deze rapportage heeft betrekking op de eerste twee onderzoeksjaren van het publiek-private samenwerking (PPS) project ‘Efficiënte keten, preventie reststromen’ (2017/2018). De ambitie van dit PPS-project is om derving (verspilling) in de biologische agrifood-keten te voorkomen, en daar waar reststromen ontstaan de kansen voor het vermarkten van deze reststromen te vergroten. Binnen dit PPS-project is sprake van twee onderzoekslijnen. Onderzoekslijn A richt zich op de preventie van derving in biologische winkels, en van de derving bij de primaire producenten. Onderzoekslijn B richt zich op het vermarkten van reststromen uit de biologische aardappelen, groenten en fruit (agf) keten, in eerste instantie van producten die afwijkend zijn qua vorm en grootte en om die reden worden afgekeurd voor verkoop via de gebruikelijke afzetkanalen. Bedrijfspartners binnen de PPS ‘Efficiënte keten, preventie reststromen’ zijn Udea/Ekoplaza, Eosta, Odin/Estafette en Green Organics. De kennispartners zijn Wageningen Food & Biobased Research en het Louis Bolk Instituut. Het doel van het PPS project is: te komen tot handvatten voor het tegengaan van derving bij primaire producenten en het voorkomen van derving in de winkels het ontwikkelen van een vermarktingsstrategie voor afwijkende agf-producten en daarmee het verminderen van reststromen uit de agf-keten, en het onderzoeken van andere mogelijkheden van het verwaarden van deze reststromen. Voor de winkelsituatie is met een simulatiemodel geprobeerd om de gemeten derving van drie geselecteerde producten in een voorbeeldwinkel te reconstrueren. Dit leidt tot productspecifieke aanbevelingen met betrekking tot onder meer het verlengen van de houdbaarheid, de presentatievoorraad en het afremmen van het selectiegedrag van de consument. Het uitvalpercentage van ca. 15-25% in de biologische primaire productie (toeleveranciers) blijkt als volgt onderverdeeld: 10-15% uitval van planten 5-10% niet-geoogst product 2% schade/verlies tijdens verpakken e.d. Belangrijke thema’s bij het terugdringen van derving bij toeleveranciers zijn verbinding in de keten, het vertellen van het verhaal naar de klant, handelsnormen en praktische verbeteringen. In het derde jaar van het project zullen voor de winkelsituatie pilots worden opgestart met betrekking tot houdbaarheidsverlenging en het inschatten van het effect van promotieacties. Ook is er een pilot voorzien tussen Eosta en Udea / Ekoplaza (‘Elastische Keten’) ten behoeve van structurele vermindering van productuitval bij Eosta

Ab-initio simulation of high-temperature liquid selenium

Ab initio molecular dynamics simulation is used to investigate the structure and dynamics of liquid Se at temperatures of 870 and 1370~K. The calculated static structure factor is in excellent agreement with experimental data. The calculated radial distribution function gives a mean coordination number close to 2, but we find a significant fraction of one-fold and three-fold atoms, particularly at 1370~K, so that the chain structure is considerably disrupted. The self-diffusion coefficient has values ($\sim 1 \times 10^{-8}$~m~s$^{-1}$) typical of liquid metals.Comment: 10 pages, 4 Poscript figures, uses REVTE

Regionale Produktketten von Bio-Brotgetreide in NÖ: Stärken, Schwächen, Chancen, Hemmnisse,Unterstützungsmaßnahmen

Regionale Produktketten - Produktketten, in denen zwischen den AkteurInnen(LandwirtInnen, BäckerInnen, MüllerInnen, KonsumentInnen) räumliche Nähe besteht – leisten besondere Beiträge zur Nachhaltigen Entwicklung (mehr Wertschöpfung und Arbeitsplätze in der Region, häufig niedrigerer Transportaufwand, Erhaltung der Kulturlandschaft, Stärkung regionaler Identität und Tradition). Zwischen Biolandbau und regionalen Produktketten gibt es ganz besondere Synergien: Die positiven Wirkungen und Ziele des Biolandbaus können auf regionaler Ebene besser umgesetzt und verstärkt werden; die KonsumentInnen setzen bei Bio-Produkten oft voraus, dass sie aus der Region stammen. In Niederösterreich (NÖ) wird - insbesondere nach dem „Umstellungsboom“ unter den Ackerbaubetrieben - viel Bio-Getreide produziert, gleichzeitig gibt es aber kaum regionale Kooperationen entlang der Produktkette. Die Anzahl der Mühlen und Bäckereien sinkt seit dem EU-Beitritt drastisch und kontinuierlich; der Löwenanteil des Bio-Getreides fließt in große Verarbeitungs- und Vermarktungsstrukturen

Recoil Distributions in Particle Transfer

Classical Thomas peaks in various fast second-order particle transfer processes are quantum mechanically broadened by energy nonconservation in the intermediate states of collision. This quantum broadening is considered in observable velocity distributions of recoil particles

Quantitative characterization of translational riboregulators using an in vitro transcription–translation system

Riboregulators are short RNA sequences that, upon binding to a ligand, change their secondary structure and influence the expression rate of a downstream gene. They constitute an attractive alternative to transcription factors for building synthetic gene regulatory networks because they can be engineered de novo. However, riboregulators are generally designed in silico and tested in vivo, which provides little quantitative information about their performances, thus hindering the improvement of design algorithms. Here we show that a cell-free transcription-translation (TX–TL) system provides valuable information about the performances of in silico designed riboregulators. We first propose a simple model that provides a quantitative definition of the dynamic range of a riboregulator. We further characterize two types of translational riboregulators composed of a cis-repressed (cr) and a trans-activating (ta) strand. At the DNA level we demonstrate that high concentrations of taDNA poisoned the activator until total shut off, in agreement with our model, and that relative dynamic ranges of riboregulators determined in vitro are in agreement with published in vivo data. At the RNA level, we show that this approach provides a fast and simple way to measure dissociation constants of functional riboregulators, in contrast to standard mobility-shift assays. Our method opens the route for using cell-free TX–TL systems for the quantitative characterization of functional riboregulators in order to improve their design in silico