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

Dehumanized and demonized refugees, zombies and world war Z

© 2019 Informa UK Limited, trading as Taylor & Francis Group. This paper explores inhuman/human constructions that feature in state responses to refugees. We move beyond straightforward normative claims that dehumanizing or demonizing refugees is unfair, unjust or bad to ask: what kind of inhuman monsters are refugees characterized as when they are ‘demonised’; and, what are the consequences of such a characterization? Our argument is that reading the demonised refugee as the contemporary zombie monster and inversely, reading the resurgence of the zombie monster through the prism of the so-called refugee and migrant crisis, reveals the precise anxieties brought about by refugees and asylum seekers. In particular, we claim that both figures represent the transgression of borders, as well as the failure of containment, borders and border walls as a response to crisis. We also argue that the contemporary zombie, as a race-less catchall monster figure, mirrors the erasure of colonial histories, race and race relations in the casting of refugees as dehistoricized, invading and disorderly bodies. We analyse these themes through the 2013 blockbuster film World War Z (dir. Marc Foster). In the film, the United Nations, US Navy, World Health Organisation, and Gerry Lane (a former UN employee) combine to fight a global zombie war

Magnetic interactions of substitutional Mn pairs in GaAs

We employ a kinetic-exchange tight-binding model to calculate the magnetic interaction and anisotropy energies of a pair of substitutional Mn atoms in GaAs as a function of their separation distance and direction. We find that the most energetically stable configuration is usually one in which the spins are ferromagnetically aligned along the vector connecting the Mn atoms. The ferromagnetic configuration is characterized by a splitting of the topmost unoccupied acceptor levels, which is visible in scanning tunneling microscope studies when the pair is close to the surface and is strongly dependent on pair orientation. The largest acceptor splittings occur when the Mn pair is oriented along the symmetry direction, and the smallest when they are oriented along . We show explicitly that the acceptor splitting is not simply related to the effective exchange interaction between the Mn local moments. The exchange interaction constant is instead more directly related to the width of the distribution of all impurity levels -- occupied and unoccupied. When the Mn pair is at the (110) GaAs surface, both acceptor splitting and effective exchange interaction are very small except for the smallest possible Mn separation.Comment: 25 figure

Magnetic properties of substitutional Mn in (110) GaAs surface and subsurface layers

Motivated by recent STM experiments, we present a theoretical study of the electronic and magnetic properties of the Mn-induced acceptor level obtained by substituting a single Ga atom in the (110) surface layer of GaAs or in one of the atoms layers below the surface. We employ a kinetic-exchange tight-binding model in which the relaxation of the (110) surface is taken into account. The acceptor wave function is strongly anisotropic in space and its detailed features depend on the depth of the sublayer in which the Mn atom is located. The local-density-of-states (LDOS) on the (110) surface associated with the acceptor level is more sensitive to the direction of the Mn magnetic moment when the Mn atom is located further below the surface. We show that the total magnetic anisotropy energy of the system is due almost entirely to the dependence of the acceptor level energy on Mn spin orientation, and that this quantity is strongly dependent on the depth of the Mn atom.Comment: 14 pages, 13 figure

Spin-orientation-dependent spatial structure of a magnetic acceptor state in a zincblende semiconductor

The spin orientation of a magnetic dopant in a zincblende semiconductor strongly influences the spatial structure of an acceptor state bound to the dopant. The acceptor state has a roughly oblate shape with the short axis aligned with the dopant's core spin. For a Mn dopant in GaAs the local density of states at a site 8 angstrom away from the dopant can change by as much by 90% when the Mn spin orientation changes. These changes in the local density of states could be probed by scanning tunneling microscopy to infer the magnetic dopant's spin orientation.Comment: 5 pages, 4 figure

Equation of motion method for Full Counting Statistics: Steady state superradiance

For the multi-mode Dicke model in a transport setting that exhibits collective boson transmissions, we construct the equation of motion for the cumulant generating function. Approximating the exact system of equations at the level of cumulant generating function and system operators at lowest order, allows us to recover master equation results of the Full Counting Statistics for certain parameter regimes at very low cost of computation. The thermodynamic limit, that is not accessible with the master equation approach, can be derived analytically for different approximations.Comment: 7 pages, 3 figures, revised version, accepted by PR

Interference-contrast optical activity: a new technique for probing the chirality of anisotropic samples and more

We introduce interference-contrast optical activity (ICOA) as a new technique for probing the chirality of anisotropic samples and more. ICOA could underpin a new class of ‘chiral microscopes’, with potential applications spanning the range of chirality and beyond. Two possible versions of ICOA are described explicitly; one designed to probe the optical rotation of a transparent sample regardless of the sample’s linear birefringence (ICOA-OR) and another designed to probe gradients in the optical rotation of a transparent sample (ICOA-GOR). Simulated results for α-quartz lead us to suggest that ICOA-GOR might be applied to help monitor the growth of chiral crystals in the pharmaceutical industry. Possible directions for future research are highlighted

Cellular Automaton Study of Time-Dynamics of Avalanche Breakdown in IMPATT Diodes

Employing a recently developed efficient cellular automaton technique for solving Boltzmann's transport equation for realistic devices, we present a detailed study of the carrier dynamics in GaAs avalanche p-i-n (IMPATT) diodes. We find that the impact ionization in reverse bias p-i-n diodes with ultrathin (less than 50 nm) intrinsic regions is triggered by Zener tunneling rather than by thermal generation. The impact generation of hot carriers occurs mainly in the low-field junction regions rather than in the high field intrinsic zone. The calculations predict significantly more minority carriers on the n-side than on the p-side