Heptagon Amplitude in the Multi-Regge Regime

As we have shown in previous work, the high energy limit of scattering amplitudes in N=4 supersymmetric Yang-Mills theory corresponds to the infrared limit of the 1-dimensional quantum integrable system that solves minimal area problems in AdS5. This insight can be developed into a systematic algorithm to compute the strong coupling limit of amplitudes in the multi-Regge regime through the solution of auxiliary Bethe Ansatz equations. We apply this procedure to compute the scattering amplitude for n=7 external gluons in different multi-Regge regions at infinite 't Hooft coupling. Our formulas are remarkably consistent with the expected form of 7-gluon Regge cut contributions in perturbative gauge theory. A full description of the general algorithm and a derivation of results will be given in a forthcoming paper.Comment: 14 page

Form and function in hillslope hydrology : in situ imaging and characterization of flow-relevant structures

Thanks to Elly Karle and the Engler-BunteInstitute, KIT, for the IC measurements of bromide. We are grateful to Selina Baldauf, Marcel Delock, Razije Fiden, Barbara Herbstritt, Lisei Köhn, Jonas Lanz, Francois Nyobeu, Marvin Reich and Begona Lorente Sistiaga for their support in the lab and during fieldwork, as well as Markus Morgner and Jean Francois Iffly for technical support and Britta Kattenstroth for hydrometeorological data acquisition. Laurent Pfister and Jean-Francois Iffly from the Luxembourg Institute of Science and Technology (LIST) are acknowledged for organizing the permissions for the experiments. Moreover, we thank Markus Weiler (University of Freiburg) for his strong support during the planning of the hillslope experiment and the preparation of the manuscript. This study is part of the DFG-funded CAOS project “From Catchments as Organised Systems to Models based on Dynamic Functional Units” (FOR 1598). The manuscript was substantially improved based on the critical and constructive comments of the anonymous reviewers, Christian Stamm and Alexander Zimmermann, and the editor Ross Woods during the open review process, which is highly appreciated.Peer reviewedPublisher PD

Whispering Gallery Mode Resonator Stabilized Narrow Linewidth Fiber Loop Laser

We demonstrate a narrow line, fiber loop laser using Erbium-doped fiber as the gain material, stabilized by using a microsphere as a transmissive frequency selective element. Stable lasing with a linewidth of 170 kHz is observed, limited by the experimental spectral resolution. A linear increase in output power and a red-shift of the lasing mode were also observed with increasing pump power. Its potential application is also discussed

Form and function in hillslope hydrology : Characterization of subsurface ow based on response observations

Acknowledgements. We are grateful to Marcel Delock, Lisei Köhn, and Marvin Reich for their support during fieldwork, as well as Markus Morgner and Jean Francois Iffly for technical support, Britta Kattenstroth for hydrometeorological data acquisition and isotope sampling, and Barbara Herbstritt and Begoña Lorente Sistiaga for laboratory work. Laurent Pfister and Jean-Francois Iffly from the Luxembourg Institute of Science and Technology (LIST) are acknowledged for organizing the permissions for the experiments and providing discharge data for Weierbach 1 and Colpach. We also want to thank Frauke K. Barthold and the two anonymous reviewers, whose thorough remarks greatly helped to improve the manuscript. This study is part of DFG-funded CAOS project “From Catchments as Organised Systems to Models based on Dynamic Functional Units” (FOR 1598). The article processing charges for this open-access publication were covered by a Research Centre of the Helmholtz Association.Peer reviewedPublisher PD

Unstable Work Records and Delay of Gratification Internal-External Control of Reinforcement and Social Desirability Response Set

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Classification and Densification of Municipal Solid Waste for Biofuels Applications

Municipal solid waste has been gaining interest as a potential feedstock for biofuels development as it is highly organic in nature and it is a waste product requiring very little processing to become a suitable feedstock. The main focus of this research project was to evaluate whether municipal solid waste (MSW) is a good source for bioenergy development, in particular, as a feedstock for conversion to biofuels. And if densification of MSW is a feasible process to integrate into waste disposal systems in Canada. These topics were addressed through a comprehensive review of classification of MSW in Canada with focus on suitability for biofuels development and a subset of experiments that produced information on the characteristics of MSW refuse-derived fuel (RDF) and the parameters required to produce a quality, densified fuel product. A review of existing systems in Canada was conducted to establish how different regions currently classify waste; then, a classification framework produced specifically for energy recovery from MSW was used to analyze the strengths and gaps in those existing systems. Finally, a discussion regarding the suitability for biofuels development in each region was made based on the analysis. The City of Edmonton was used as the reference jurisdiction due to their established waste-to-biofuels project, and a geographic distribution of regions that were reviewed included Vancouver, Saskatoon, Toronto, and Halifax. The review determined that most jurisdiction classify MSW by material or product, with the former method being more suitable for investigating alternative utilization methods. Each region has potential for pursuing biofuels development, however, the greatest barrier appears to be whether there is a driving socio-political reason for doing so in the area. Characterization of MSW-RDF fluff sample received from Edmonton showed that the composition of the material was approximately 35% paper, 22% plastics, 14% fabrics, 6% organics/wood, and 23% fines by mass. The RDF was densified, as well as the biodegradable (paper and wood) fraction of the RDF stream to compare quality of pellets for the two material compositions. A characterization of the thermochemical and biochemical properties of MSW RDF-fluff was conducted to evaluate the suitability of MSW RDF-fluff for biofuels application. The ash content of RDF material was 19-39% while that of the biodegradable material samples was 20-23%. Proximate analysis resulted in a CHNS ratio of 33-41% carbon, 5-6% hydrogen, 0.6-0.8% nitrogen, and 0.2-0.5% sulfur for all samples. From the results of the proximate analysis, the higher heating value (HHV) for MSW RDF-fluff was calculated to be 14-16 MJ/kg. Fibre analysis of the biodegradable fraction determined that it contained 28% insoluble lignin, 1 % soluble lignin, 22% glucose, and 0% xylose. A single pelleting trial was conducted to examine the compaction parameters that would produce high quality pellets: grind size, moisture content, pelleting pressure, and pelleting temperature. It was determined that quality pellets, for both materials, were formed at a grind size of 6.35 mm at 16% moisture under pelleting conditions of 90°C and 4000 N applied load. The compact density of pellets produced from RDF ranged from 880-1020 kg/m3; the compact density of the biodegradable pellets ranged from 1120-1290 kg/m3. Fitting of the Walker and Jones models to the experimental data both indicated that the biodegradable material fraction has a higher compressibility than the RDF material, where neither moisture content nor grind size at all levels had a significant effect on the compressibility of either material. The Kawakita-Lüdde model estimated the porosity of the pelleted samples, while the Cooper-Eaton model indicated that the primary mechanism of densification was particle rearrangement. Application of the Peleg and Moreyra model for analysis of relaxation properties of the compressed materials determined the asymptotic modulus of the residual stress to be between 89 and 117 MPa for all experimental parameters; however, the RDF material produced more rigid pellets than the biodegradable material. Pilot-scale pelleting was then completed to emulate industrial pelleting process utilizing the parameters from the single pelleting operation that were deemed to produce quality pellets. All six of the sample treatments produced durable pellets (88-94%), with the ash content around 20% for all samples. A techno-economic feasibility study determined that 6.35 mm diameter pellets could be produced for an average cost of $38/Mg and includes both size reduction and densification procedures, although the aggressive process of the size reduction required indicates that it may not be a technically feasible option

Sub-kHz lasing of a CaF_2 Whispering Gallery Mode Resonator Stabilized Fiber Ring Laser

We utilize a high quality calcium fluoride whispering-gallery-mode resonator to stabilize a simple erbium doped fiber ring laser with an emission frequency of 196 THz (wavelenght 1530 nm) to a linewidth below 650 Hz. This corresponds to a relative stability of 3.3 x 10^(-12) over 16 \mus. In order to characterize the linewidth we use two identical self-built lasers and a commercial laser to determine the individual lasing linewidth via the three-cornered hat method.Comment: 4 pages, 3 figure