The ordering of green values: ecological justification in public fracking controversies in Germany and Poland

The article presents a comparative study of shale gas media debates in Germany and Poland. Drawing from the Sociology of Knowledge Approach to Discourse (SKAD), it addresses discursive conflicts over the use of hydraulic fracturing and its environmental impacts in both countries. The authors relate their analysis to the theoretical debate that emerged in the 1990s in French sociology concerning the question of “green justifications” that form a specific way of how social actors intervene, dispute, and build compromises in public discussions to protect non-human entities. Referring to these discussions, this article identifies several ecological justification clusters and the associated social actors that are ‘compromised’ or enclosed in existing orders of worth

Controlled Irradiative Formation of Penitentes

Spike-shaped structures are produced by light-driven ablation in very different contexts. Penitentes 1-4 m high are common on Andean glaciers, where their formation changes glacier dynamics and hydrology. Laser ablation can produce cones 10-100 microns high with a variety of proposed applications in materials science. We report the first laboratory generation of centimeter-scale snow and ice penitentes. Systematically varying conditions allows identification of the essential parameters controlling the formation of ablation structures. We demonstrate that penitente initiation and coarsening requires cold temperatures, so that ablation leads to sublimation rather than melting. Once penitentes have formed, further growth of height can occur by melting. The penitentes intially appear as small structures (3 mm high) and grow by coarsening to 1-5 cm high. Our results are an important step towards understanding and controlling ablation morphologies.Comment: Accepted for publication in Physical Review Letter

Catastrophic versus microscopic damage: applicability of laboratory measurements to real systems

At ultraviolet wavelengths, damage to both coatings and bare surfaces is dominated by the presence of discrete localized defects. During multiple-shot irradition, the overwhelming majority of these defects are damaged by the first or first few shots. Initially, damage morphology is that of a crater of approximately 10 microns in diameter; however, upon continued irradiation, one of two events can occur; either the crater grows to catastrophic dimensions or it remains unchanged. In the latter case, the damage is only observable under a microscope, it may be indistinguishable from cosmetic defects before irradiation, and it is likely that any related degradation in optical performance is unmeasurable. In view of the generally accepted definition of laser damage (i.e. any visible change in the surface), it is important to consider the implications for real systems. These are discussed in the context of ultraviolet test results for both coatings and surfaces

Angular dependent vortex pinning mechanisms in YBCO coated conductors and thin films

We present a comparative study of the angular dependent critical current density in YBa2Cu3O7 films deposited on IBAD MgO and on single crystal MgO and SrTiO3 substrates. We identify three angular regimes where pinning is dominated by different types of correlated and uncorrelated defects. We show that those regimes are present in all cases, indicating that the pinning mechanisms are the same, but their extension and characteristics are sample dependent, reflecting the quantitative differences in texture and defect density. In particular, the more defective nature of the films on IBAD turns into an advantage as it results in stronger vortex pinning, demonstrating that the critical current density of the films on single crystals is not an upper limit for the performance of the IBAD coated conductors.Comment: 14 pages, 3 figures. Submitted to AP

Effective Swarm Parameters And Transport Coefficients In CO2 Laser Mixtures

A pulsed electron swarm technique has been used to obtain effective attachment and ionization cross-sections as well as electron drift velocities in mixtures of CO2 laser interest. In binary CO2:N 2 mixtures, below a reduced electric field of E/N=60*10 -17 V cm2, attachment was the principal ion production process. (N is the total gas number density.) The reduced attachment coefficients measured were small and in excellent agreement with numerical predictions. In ternary mixtures of He:CO2:N2, positive ion formation described by Townsend\u27s first ionisation coefficient played a more important role over the same range of E/N. The reduced coefficient for total ion formation was measured and found to be in good agreement with numerical calculations. Electron drift velocities in both the binary and ternary mixtures were determined using a time-of-flight technique. Overall agreement with previous experimental and numerical results was good

The NMDA receptor activation by D-serine and glycine is controlled by an astrocytic Phgdh-dependent serine shuttle

Astrocytes express the 3-phosphoglycerate dehydrogenase (Phgdh) enzyme required for the synthesis of L-serine from glucose. Astrocytic L-serine was proposed to regulate NMDAR activity by shuttling to neurons to sustain D-serine production, but this hypothesis remains untested. We now report that inhibition of astrocytic Phgdh suppressed the de novo synthesis of L-and D-serine and reduced the NMDAR synaptic potentials and long-term potentiation (LTP) at the Schaffer collaterals-CA1 synapse. Likewise, enzymatic removal of extracellular L-serine impaired LTP, supporting an L-serine shuttle mechanism between glia and neurons in generating the NMDAR coagonist D-serine. Moreover, deletion of serine racemase (SR) in glutamatergic neurons abrogated D-serine synthesis to the same extent as Phgdh inhibition, suggesting that neurons are the predominant source of the newly synthesized D-serine. We also found that the synaptic NMDAR activation in adult SR-knockout (KO) mice requires Phgdh-derived glycine, despite the sharp decline in the postnatal glycine levels as a result of the emergence of the glycine cleavage system. Unexpectedly, we also discovered that glycine regulates D-serine metabolism by a dual mechanism. The first consists of tonic inhibition of SR by intracellular glycine observed in vitro, primary cultures, and in vivo microdialysis. The second involves a transient glycine-induce D-serine release through the Asc-1 transporter, an effect abolished in Asc-1 KO mice and diminished by deleting SR in glutamatergic neurons. Our observations suggest that glycine is a multifaceted regulator of D-serine metabolism and implicate both D-serine and glycine in mediating NMDAR synaptic activation at the mature hippocampus through a Phgdh-dependent shuttle mechanism

Strongly Enhanced Current Densities in Superconducting Coated Conductors of YBa2Cu3O7-x + BaZrO3

There are numerous potential applications for superconducting tapes, based on YBa2Cu3O7-x (YBCO) films coated onto metallic substrates. A long established goal of more than 15 years has been to understand the magnetic flux pinning mechanisms which allow films to maintain high current densities out to high magnetic fields. In fact, films carry 1-2 orders of magnitude higher current densities than any other form of the material. For this reason, the idea of further improving pinning has received little attention. Now that commercialisation of conductors is much closer, for both better performance and lower fabrication costs, an important goal is to achieve enhanced pinning in a practical way. In this work, we demonstrate a simple and industrially scaleable route which yields a 1.5 to 5-fold improvement in the in-field current densities of already-high-quality conductors

High-temperature change of the creep rate in YBa 2Cu 3O 7-δ films with different pinning landscapes

Magnetic relaxation measurements in YBa 2Cu 3O 7-δ (YBCO) films at intermediate and high temperatures show that the collective vortex creep based on the elastic motion of the vortex lattice has a crossover to fast creep that significantly reduces the superconducting critical current density (J c). This crossover occurs at temperatures much lower than the irreversibility field line. We study the influence of different kinds of crystalline defects, such as nanorods, twin boundaries, and nanoparticles, on the high-temperature vortex phase diagram of YBCO films. We found that the magnetization relaxation data is a fundamental tool to understand the pinning at high temperatures. The results indicate that high J c values are directly associated with small creep rates. Based on the analysis of the depinning temperature in films with columnar defects, our results indicate that the size of the defects is the relevant parameter that determines thermal depinning at high temperatures. Also, the extension of the collective creep regime depends on the density of the pinning centers.Fil: Haberkorn, Nestor Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Miura, M.. No especifíca;Fil: Baca, J.. No especifíca;Fil: Maiorov, B.. No especifíca;Fil: Usov, I.. No especifíca;Fil: Dowden, P.. No especifíca;Fil: Foltyn, S. R.. No especifíca;Fil: Holesinger, T. G.. No especifíca;Fil: Willis, J. O.. No especifíca;Fil: Marken, K. R.. No especifíca;Fil: Izumi, T.. No especifíca;Fil: Shiohara, Y.. No especifíca;Fil: Civale, L.. No especifíca

Processing of YBCO/IBAD YSZ coated conductors on flexible substrates

Continuous coaters capable of producing 1.1 m long x 1 cm wide tapes of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} (YBCO) on biaxially oriented yttria-stabilized zirconia (YSZ) on flexible Ni-alloy substrates have been developed at this laboratory. Using a 1 {micro}V/cm criterion, the authors have achieved transport critical current (I{sub c}) values of 29 A (75 K, self field) between voltage taps spaced 1 m apart. The corresponding critical current density (J{sub c}) value for this tape is 290 kA/cm{sup 2}. For shorter tapes, (12 cm voltage tap separation) they have attained J{sub c} values of 0.67 MA/cm{sup 2}. Individual 1 x 1 cm sections within these shorter tapes have attained J{sub c} values of 1 MA/cm{sup 2}

Magneto-optical imaging and current distributions in high-{Tc} superconductors

Recent studies on the magneto-optical (MO) imaging of the magnetic flux and current distributions in polycrystalline high-{Tc} superconductors are summarized. The authors studied a wide spectrum of high-{Tc} materials, from single grain boundaries in YBCO bicrystals, to polycrystalline YBCO thick films deposited on an IBAD-buffer layer grown on a polycrystalline Hastelloy substrate, to Bi-2223 tapes. In all cases they found that structural defects (e.g., high-angle grain boundaries, second phase precipitates, microcrack networks, etc.) significantly limit the current-carrying capability. These defects make the magnetic flux distribution highly inhomogeneous, in turn producing granular and percolative current flow. By inverting the Biot-Savart law for thin film and slab geometries, they were able to reconstruct the local current flow patterns around defects and thus identify the current-carrying percolative paths and map the distribution of local critical currents J{sub c}(r). Such studies show that, even in high-J{sub c} materials, the local J{sub c}(r) can vary by a factor 2--10 due to defects. Since the maximum local J{sub c}(r) values can significantly exceed the numbers obtained by transport measurements, it is clear that there are still significant opportunities for raising the J{sub c} of polycrystalline HTS conductors