Spin asymmetry at large x_F and k_T

We suggest that the large single spin asymmetries observed at high momentum fractions x_F and transverse momenta k_T of the pion in p^\uparrow p -> \pi(x_F,k_T)+X arise from the coherence of the soft interactions with the hard parton scattering process. Such coherence can be maintained if x_F -> 1 as k_T -> \infty, while k_T^2(1-x_F) ~ \Lambda_{QCD}^2 stays fixed. Analogous coherence effects have been seen experimentally in the Drell-Yan process at high x_F. We find that the p^\uparrow p -> \pi X production amplitudes have large dynamic phases and that helicity flip contributions are unsuppressed in this limit, giving rise to potentially large single spin asymmetries.Comment: 3 pages, 1 figure. Talk given at EPS HEP 2007, Mancheste

Single Spin Asymmetry at Large x_F and k_T

The large single spin asymmetries observed at high momentum fractions x_F and transverse momenta k_T in p^\uparrow p -> \pi(x_F,k_T)+X as well as in pp -> \Lambda^\uparrow(x_F,k_T)+X suggest that soft helicity flip processes are coherent with hard scattering. Such coherence can be maintained if x_F -> 1 as k_T -> \infty, while k_T^2(1-x_F) \sim \Lambda_QCD^2 stays fixed. The entire hadron wave function, rather than a single quark, then contributes to the scattering process. Analogous coherence effects have been seen experimentally in the Drell-Yan process at high x_F. We find that the p^\uparrow p -> \pi(x_F,k_T)+X production amplitudes have large dynamic phases and that helicity flip contributions are unsuppressed in this limit, giving rise to potentially large single spin asymmetries.Comment: 11 pages, 2 figures. v2: References and a preprint number added. Calculation of section 4 modified. v3: Minor changes in text. Version to be published in JHE

Application of ERTS-1 Imagery to Flood Inundation Mapping

Application of ERTS-1 imagery to flood inundation mapping in East and West Nishnabotna basins of southwestern Iow

Realistic and verifiable coherent control of excitonic states in a light harvesting complex

We explore the feasibility of coherent control of excitonic dynamics in light harvesting complexes, analyzing the limits imposed by the open nature of these quantum systems. We establish feasible targets for phase and phase/amplitude control of the electronically excited state populations in the Fenna-Mathews-Olson (FMO) complex and analyze the robustness of this control with respect to orientational and energetic disorder, as well as decoherence arising from coupling to the protein environment. We further present two possible routes to verification of the control target, with simulations for the FMO complex showing that steering of the excited state is experimentally verifiable either by extending excitonic coherence or by producing novel states in a pump-probe setup. Our results provide a first step toward coherent control of these complex biological quantum systems in an ultrafast spectroscopy setup.Comment: 12 pages, 8 figure

Interpretation of High Energy String Scattering in terms of String Configurations

High energy string scattering at fixed momentum transfer, known to be dominated by Regge trajectory exchange, is interpreted by identifying families of string states which induce each type of trajectory exchange. These include the usual leading trajectory $\alpha(t)=\alpha^\prime t+1$ and its daughters as well as the ``sister'' trajectories $\alpha_m(t)=\alpha(t)/m-(m-1)/2$ and their daughters. The contribution of the sister $\alpha_m$ to high energy scattering is dominated by string excitations in the $m^{th}$ mode. Thus, at large $-t$, string scattering is dominated by wee partons, consistently with a picture of string as an infinitely composite system of ``constituents'' which carry zero energy and momentum.Comment: 14 pages, phyzzx, psfig required, Florida Preprint UFIFT-94-

Einfluss des ökologischen Landbaus auf unterschiedliche Humuspools im Boden und Schlussfolgerungen zur Humusbilanzierung

Due to the results of organic matter balancing which showed a very high potential of soil organic matter accumulation in organic farming, a research project was started in spring 2005 with the objective to ascertain this hypothesis. Soil sampling was carried out on different organic and adjacent conventional farms in distinct regions of Ger-many. A comparison of the samples regarding Corg showed only minor differences between organic and conventional farms whereas the more sensitive indicators like Cmic and enzyme activities were more affected. However the main influencing factor of all these indicators in this investigation is soil texture. The cultivation system (inten-sive, extensive, stocking, crop rotation, tillage) is more important than the differentia-tion organic or conventional farming

A Participatory Process to Develop a Landslide Warning System: Paradoxes of Responsibility Sharing in a Case Study in Upper Austria

During a participatory process in Gmunden, Austria, the organizational and responsibility-sharing arrangements for a landslide warning system proved to be contested issues. While questions on the warning system technology and the distribution of information, including the alarm for evacuation, could be resolved with the support of experts, controversies arose on the financial and legal responsibilities that ensure long-term and effective monitoring for the protection of the landslide-prone community. This paper examines how responsibilities can be shared among the residents, experts, and public authorities during the design and operation of landslide warning systems. In particular, we discuss the outcome and implications of three stakeholder workshops where participants deliberated on warning-system options that, in turn, were based on a discourse analysis of extensive stakeholder interviews. The results of the case study show that an end-user orientation requires the consideration of stakeholder worldviews, interests, and conflicts. Paradoxically, the public did not fully support their own involvement in the maintenance and control of the warning system, but the authorities promoted shared responsibility. Deliberative planning does not then necessarily lead to responsibility sharing, but it proved effective as a platform for information and for shared ownership in the warning syste

Vibration-enhanced quantum transport

In this paper, we study the role of collective vibrational motion in the phenomenon of electronic energy transfer (EET) along a chain of coupled electronic dipoles with varying excitation frequencies. Previous experimental work on EET in conjugated polymer samples has suggested that the common structural framework of the macromolecule introduces correlations in the energy gap fluctuations which cause coherent EET. Inspired by these results, we present a simple model in which a driven nanomechanical resonator mode modulates the excitation energy of coupled quantum dots and find that this can indeed lead to an enhancement in the transport of excitations across the quantum network. Disorder of the on-site energies is a key requirement for this to occur. We also show that in this solid state system phase information is partially retained in the transfer process, as experimentally demonstrated in conjugated polymer samples. Consequently, this mechanism of vibration enhanced quantum transport might find applications in quantum information transfer of qubit states or entanglement.Comment: 7 pages, 6 figures, new material, included references, final published versio

Influence of Coulomb and Phonon Interaction on the Exciton Formation Dynamics in Semiconductor Heterostructures

A microscopic theory is developed to analyze the dynamics of exciton formation out of incoherent carriers in semiconductor heterostructures. The carrier Coulomb and phonon interaction is included consistently. A cluster expansion method is used to systematically truncate the hierarchy problem. By including all correlations up to the four-point (i.e. two-particle) level, the fundamental fermionic substructure of excitons is fully included. The analysis shows that the exciton formation is an intricate process where Coulomb correlations rapidly build up on a picosecond time scale while phonon dynamics leads to true exciton formation on a slow nanosecond time scale.Comment: 18 pages, 7 figure

Agricultural productivity in past societies: toward an empirically informed model for testing cultural evolutionary hypotheses

Agricultural productivity, and its variation in space and time, plays a fundamental role in many theories of human social evolution. However, we often lack systematic information about the productivity of past agricultural systems on a scale large enough to test these theories properly. The effect of climate on crop yields has received a great deal of attention resulting in a range of empirical and process-based models, yet the focus has primarily been on current or future conditions. In this paper, we argue for a “bottom-up” approach that estimates potential productivity based on information about the agricultural practices and technologies used in past societies. Of key theoretical interest is using this information to estimate the carrying high quality historical and archaeological information about past societies in order to infer the temporal and geographic patterns of change in agricultural productivity and potential. We discuss information we need to collect about past agricultural techniques and practices, and introduce a new databank initiative that we have developed for collating the best available historical and archaeological evidence. A key benefit of our approach lies in making explicit the steps in the estimation of past productivities and carrying capacities, and in being able to assess the effects of different modelling assumptions. This is undoubtedly an ambitious task, yet promises to provide important insights into fundamental aspects of past societies, enabling us to test more rigorously key hypotheses about human socio-cultural evolution