On the calculation of the topographic wetness index: evaluation of different methods based on field observations

The topographic wetness index (TWI, ln(<i>a</i>/tan<I>&beta;</I>)), which combines local upslope contributing area and slope, is commonly used to quantify topographic control on hydrological processes. Methods of computing this index differ primarily in the way the upslope contributing area is calculated. In this study we compared a number of calculation methods for TWI and evaluated them in terms of their correlation with the following measured variables: vascular plant species richness, soil pH, groundwater level, soil moisture, and a constructed wetness degree. The TWI was calculated by varying six parameters affecting the distribution of accumulated area among downslope cells and by varying the way the slope was calculated. All possible combinations of these parameters were calculated for two separate boreal forest sites in northern Sweden. We did not find a calculation method that performed best for all measured variables; rather the best methods seemed to be variable and site specific. However, we were able to identify some general characteristics of the best methods for different groups of measured variables. The results provide guiding principles for choosing the best method for estimating species richness, soil pH, groundwater level, and soil moisture by the TWI derived from digital elevation models

Intersecting Knowledge Fields and Integrating Data-Driven Computational Design en Route to Performance-Oriented and Intensely Local Architectures

This paper discusses research by design efforts in architectural education, focused on developing concepts and methods for the design of performance-oriented and intensely local architectures. The pursued notion of performance foregrounds the interaction between a given architecture and its local setting, with consequences not only for the design product but also for the related processes by which it is generated. Integrated approaches to data-driven computational design serve to generate such designs. The outlined approach shifts the focus of design attention away from the delivery of finite architectural objects and towards an expanded range of architecture-environment interactions that are registered, instrumentalised and modulated over time. This paper examines ongoing efforts in integrating specific architectural goals and approaches, computational data-driven design methods and generative design processes, based on a range of context-specific and often real-time data sets. The work discussed is produced in the context of the Research Centre for Architecture and Tectonics (RCAT) and the Advanced Computational Design Laboratory (ACDL) at the Oslo School of Architecture and Design

Bogoliubov theory of entanglement in a Bose-Einstein condensate

We consider a Bose-Einstein condensate which is illuminated by a short resonant light pulse that coherently couples two internal states of the atoms. We show that the subsequent time evolution prepares the atoms in an interesting entangled state called a spin squeezed state. This evolution is analysed in detail by developing a Bogoliubov theory which describes the entanglement of the atoms. Our calculation is a consistent expansion in $1/\sqrt{N}$, where $N$ is the number of particles in the condensate, and our theory predict that it is possible to produce spin squeezing by at least a factor of $1/\sqrt{N}$. Within the Bogoliubov approximation this result is independent of temperature.Comment: 14 pages, including 5 figures, minor changes in the presentatio

The presence and activity of SP-D in porcine coronary endothelial cells depend on Akt/PI3K, Erk and nitric oxide and decrease after multiple passaging

Surfactant protein D (SP-D) mediates clearance of microorganisms and modulates inflammation in response to cytotoxic stimulation. It is present in various epithelia, but also in vascular smooth muscle and endothelial cells. Experiments were designed to determine whether or not SP-D is present in porcine coronary arterial endothelial cells and if so, to investigate the molecular mechanisms underlying this presence. The expression of SP-D, NO synthase, Akt 1/2 and Erk 1/2 proteins was determined in cultures at passages 1 (#1) and 4 (#4). SP-D in primary cells existed in three isoforms (37-38 kDa and 50 kDa). The 37-38 kDa SP-D forms were the dominant isoforms in the porcine endothelium and were prominent at #1 but partially lost at #4. Tumor necrosis factor-α (TNF-α) significantly augmented the level of SP-D expression at #1 but not at #4. The basal level of 37-38 kDa SP-D isoforms at #1 was reduced by L-NAME, wortmannin and PD 98059. The low basal expression at #4 could be increased by DETA NONOate (donor of NO) or insulin (activator of PI3K/Akt). The presence of nitric oxide synthase was reduced while that of Akt 1/2 and Erk 1/2 was increased at #4. In cells both at passages 1 and 4, TNF-α downregulated NO synthase and up-regulated p-Erk 1/2 protein. The present findings demonstrate the presence of SP-D in endothelial cells which is NO-, PI3K/Akt- and Erk-dependent. They suggest a protective role of SP-D in these cells. © 2008 Elsevier Ltd. All rights reserved.postprin

Environment Assisted Metrology with Spin Qubit

We investigate the sensitivity of a recently proposed method for precision measurement [Phys. Rev. Lett. 106, 140502 (2011)], focusing on an implementation based on solid-state spin systems. The scheme amplifies a quantum sensor response to weak external fields by exploiting its coupling to spin impurities in the environment. We analyze the limits to the sensitivity due to decoherence and propose dynamical decoupling schemes to increase the spin coherence time. The sensitivity is also limited by the environment spin polarization; therefore we discuss strategies to polarize the environment spins and present a method to extend the scheme to the case of zero polarization. The coherence time and polarization determine a figure of merit for the environment's ability to enhance the sensitivity compared to echo-based sensing schemes. This figure of merit can be used to engineer optimized samples for high-sensitivity nanoscale magnetic sensing, such as diamond nanocrystals with controlled impurity density.Comment: 9 pages, 6 figure

Environment Assisted Precision Measurement

We describe a method to enhance the sensitivity of precision measurements that takes advantage of a quantum sensor's environment to amplify its response to weak external perturbations. An individual qubit is used to sense the dynamics of surrounding ancillary qubits, which are in turn affected by the external field to be measured. The resulting sensitivity enhancement is determined by the number of ancillas that are coupled strongly to the sensor qubit; it does not depend on the exact values of the coupling strengths and is resilient to many forms of decoherence. The method achieves nearly Heisenberg-limited precision measurement, using a novel class of entangled states. We discuss specific applications to improve clock sensitivity using trapped ions and magnetic sensing based on electronic spins in diamond.Comment: 4 pages, 3 figure