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Background Slick, a sodium-activated potassium channel, has been recently identified in somatosensory pathways, but its functional role is poorly understood. The authors of this study hypothesized that Slick is involved in processing sensations of pain and itch. Methods Immunostaining, in situ hybridization, Western blot, and real-time quantitative reverse transcription polymerase chain reaction were used to investigate the expression of Slick in dorsal root ganglia and the spinal cord. Mice lacking Slick globally (Slick–/–) or conditionally in neurons of the spinal dorsal horn (Lbx1-Slick–/–) were assessed in behavioral models. Results The authors found Slick to be enriched in nociceptive Aδ-fibers and in populations of interneurons in the spinal dorsal horn. Slick–/– mice, but not Lbx1-Slick–/– mice, showed enhanced responses to noxious heat in the hot plate and tail-immersion tests. Both Slick–/– and Lbx1-Slick–/– mice demonstrated prolonged paw licking after capsaicin injection (mean ± SD, 45.6 ± 30.1 s [95% CI, 19.8 to 71.4]; and 13.1 ± 16.1 s [95% CI, 1.8 to 28.0]; P = 0.006 [Slick–/– {n = 8} and wild-type {n = 7}, respectively]), which was paralleled by increased phosphorylation of the neuronal activity marker extracellular signal–regulated kinase in the spinal cord. In the spinal dorsal horn, Slick is colocalized with somatostatin receptor 2 (SSTR2), and intrathecal preadministration of the SSTR2 antagonist CYN-154806 prevented increased capsaicin-induced licking in Slick–/– and Lbx1-Slick–/– mice. Moreover, scratching after intrathecal delivery of the somatostatin analog octreotide was considerably reduced in Slick–/– and Lbx1-Slick–/– mice (Slick–/– [n = 8]: 6.1 ± 6.7 bouts [95% CI, 0.6 to 11.7]; wild-type [n =8]: 47.4 ± 51.1 bouts [95% CI, 4.8 to 90.2]; P = 0.039). Conclusions Slick expressed in a subset of sensory neurons modulates heat-induced pain, while Slick expressed in spinal cord interneurons inhibits capsaicin-induced pain but facilitates somatostatin-induced itch. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

The transient receptor potential (TRP) ankyrin type 1 (TRPA1) channel is highly expressed in a subset of sensory neurons where it acts as an essential detector of painful stimuli. However, the mechanisms that control the activity of sensory neurons upon TRPA1 activation remain poorly understood. Here, using in situ hybridization and immunostaining, we found TRPA1 to be extensively co-localized with the potassium channel Slack (KNa1.1, Slo2.2, or Kcnt1) in sensory neurons. Mice lacking Slack globally (Slack−/−) or conditionally in sensory neurons (SNS-Slack−/−) demonstrated increased pain behavior after intraplantar injection of the TRPA1 activator allyl isothiocyanate. By contrast, pain behavior induced by the TRP vanilloid 1 (TRPV1) activator capsaicin was normal in Slack-deficient mice. Patch-clamp recordings in sensory neurons and in a HEK cell line transfected with TRPA1 and Slack revealed that Slack-dependent potassium currents (IKS) are modulated in a TRPA1-dependent manner. Taken together, our findings highlight Slack as a modulator of TRPA1-mediated, but not TRPV1-mediated, activation of sensory neurons.

The development of new automotive drivetrain layouts requires modeling of the involved components to allow for ideal control strategies. The creation of these models is both costly and challenging, specifically because interpretability, accuracy, and computational effort need to be balanced. In this study, a method is put forward which supports experts in the modeling process and in making an educated choice to balance these constraints. The method is based on the artificial intelligence technique of genetic programming. By solving a symbolic regression problem, it automatically identifies equation-based models from data. To address possible system complexities, data-based expressions like curves and maps can additionally be employed for the model identification. The performance of the method is demonstrated based on two examples: 1. Identification of a pure equation based model, demonstrating the benefit of interpretability. 2. Creation of a hybrid-model, combining a base equation with data-based expressions. Possible applications of the method are model creation, system identification, structural optimization, and model reduction. The existing implementation in ETAS ASCMO-MOCA also offers a high efficiency increase by combining and automating the two procedural steps of embedded function engineering and calibration.

The dynamics of an elastic bar that appears in two phases can be described by viscositycapillarity models. They contain numerically complicated third-order or fully nonlocal terms to account for surface energies. Based on work of Solci&Vitali we analyze an alternative modelling approach that does not involve third-order differential operators. It is proven that solutions of the new model tend to solutions of the classical viscosity-capillarity model provided a so-called coupling parameter tends to infinity. Numerical experiments illustrate our findings. In fact it is shown that the new model provides a reliable and efficient approach to compute approximate solutions for the classical viscosity-capillarity model. Preprint Series Issue No. 2012 Stuttgart Research Centre for Simulation Technology (SRC SimTech) SimTech – Cluster of Excellence Pfaffenwaldring 7a 70569 Stuttgart publications@simtech.uni-stuttgart.de www.simtech.uni-stuttgart.de A Low-Order Approximation for Viscous-Capillary Phase Transition Dynamics Patrick Engel Universitat Stuttgart, Institut fur Angewandte Analysis und Numerische Simulation, Pfaffenwaldring 57, D-70569 Stuttgart, Germany patrick.engel@mathematik.uni-stuttgart.de Adrian Viorel Babes–Bolyai University, Department of Applied Mathematics, Kogalniceanu 3, RO-400084 Cluj-Napoca, Romania adrian.viorel@math.ubbcluj.ro Christian Rohde Universitat Stuttgart, Institut fur Angewandte Analysis und Numerische Simulation, Pfaffenwaldring 57, D-70569 Stuttgart, Germany christian.rohde@mathematik.uni-stuttgart.de October 5, 2012

This paper reviews the development and methodology of a workshop on the application of spatial information in the implementation of land reform in South Africa. The specific methods of spatial information dealt with include aerial photographs, maps of the national series and cadastral records. The delivery of land rights is the core business of the Department of Land Affairs in South Africa. At the same time, translating this statement into practice remains one of the greatest challenges facing South Africa. In order to do this the people driving this process must be skilled in the application of specific spatial information. First, a frame of reference on developing map-reading skills is presented; second, there is a review the development and implementation of the workshop. Third, the findings of the workshop are expanded upon. In conclusion we have a look at the way ahead.

Submitted paper; Undercompressive shock waves arise in numerous physical applications. We propose a class of conservative finite-volume type schemes to approximate weak solutions of conservation laws that contain undercompressive shock waves. We prove the convergence of a subsequence of approximate solutions towards a generalized entropy solution if the mesh width tends to zero. The proof relies on a refined BV compactness analysis, which accounts for the effect of the kinetic relation that drives the undercompressive wave. At the same time we establish a new proof for the existence of solutions to the underlying model. Numerical experiments supplement the analytical results.

International audience; Phase transition problems in compressible media can be modelled by mixed hyperbolicelliptic systems of conservation laws. Within this approach phase boundaries are understood as shock waves that satisfy additional constraints, sometimes called kinetic relations. In recent years several tracking-type algorithms have been suggested for numerical approximation. Typically a core piece of these algorithms is the usage of exact Riemann solvers incorporating the kinetic relation at the location of phase boundaries. However, exact Riemann solvers are computationally expensive or even not available. In this paper we present a class of approximate Riemann solvers for hyperbolic-elliptic models that relies on a generalized relaxation procedure. It preserves in particular the kinetic relation for phase boundaries exactly and gives for isolated phase transitions the correct solutions. In combination with a novel sub-iteration procedure the approximate Riemann solvers are used in the tracking algorithms. The efficiency of the approach is validated on a barotropic system with linear kinetic relation where exact Riemann solvers are available. For a nonlinear kinetic relation and a thermoelastic system we use the new method to gain information on the Riemann problem. Up to our knowledge an exact solution for arbitrary Riemann data is currently not available in these cases.