Shawn: A new approach to simulating wireless sensor networks

We consider the simulation of wireless sensor networks (WSN) using a new approach. We present Shawn, an open-source discrete-event simulator that has considerable differences to all other existing simulators. Shawn is very powerful in simulating large scale networks with an abstract point of view. It is, to the best of our knowledge, the first simulator to support generic high-level algorithms as well as distributed protocols on exactly the same underlying networks.Comment: 10 pages, 2 figures, 2 tables, Latex, to appear in Design, Analysis, and Simulation of Distributed Systems 200

Biodiversidad y estructura del mega-epibentos en la región de Magallanes (América del Sur)

Epibenthic communites have been investigated at 55 stations in the Magellan region by underwater photogra-phy at water depths between 15 and 430m. Five species assemblages were identified of which the two shallow and the two deep ones in the channel system differed considerably in abundance, number of taxa, diversity and species composition. The dominant systematic group of the shallow assemblages were ascidians. In one of these assemblages decapod crustaceans, in the other mainly sessile suspension feeders e.g. sponges, anthozoans and bryozoans were the characteristic taxa. In the deeper assemblages echinoderms were most abundant. The fifth assemblage, consisting of several offshore stations south of the eastern entrance of the Beagle, was more similar to the shallow stations in the channel system in terms of dominant life forms. Various hypotheses were confirmed or rejected: The benthos at the deeper stations in the channel system was not more homogeneous than at the shallow stations. At both the channel and the offshore stations filter feeders were most dominant whereas at the bottom of the channels deposit feeders were more abundant. Differences between the wide Straits of Magellan and the narrow and steep Beagle Channel were not very distinct. The benthic assemblages inside the channel system did not differ considerably from the assemblage outside the channel system with the exception of the stations close to the continental slope of the Atlantic. Differences due to Pacific or Atlantic influences were not recognisable. The biological patterns could best be explained by the environmental parameters water depth, occurrence of soft sediment and biogenic debris.Se estudiaron las comunidades epibentónicas en 55 estaciones de la región de Magallanes en profundidades entre 15 y 430 m mediante fotografía subacuática. Se identificaron cinco comunidades distintas. Las dos comunidades someras y las dos profundas en el sistema de canales revelaron diferencias considerables en lo que se refiere a abundancia, número de taxones, diversidad y composición específica. Las ascidias predominaron en las comunidades someras. En una de ellas, los crustáceos decápodos fueron el taxón característico mientras en la otra lo fueron los suspensívoros sésiles tales como esponjas, antozoos o briozoos. En las comunidades de mayor profundidad los equinodermos fueron el grupo más notable. La quinta comunidad, compuesta por varias estaciones situadas al sur de la entrada este del Canal del Beagle, resultó ser muy parecida a la de las estaciones someras en el sistema de canales en términos de formas de vida dominantes. Se aceptaron o rechazaron varias hipótesis. El bentos en las estaciones más profundas del sistema de canales no se mostró más homogéneo que en las estaciones someras. Tanto en las estaciones cercanas como en las estaciones fuera de la costa predominaron los suspensívoros, mientras que los detritívoros fueron el grupo dominante en el fondo de los canales. No se detectaron diferencias muy marcadas entre el Estrecho de Magallanes, de configuración ancha, y el Canal del Beagle de forma estrecha y pendiente fuerte. Con excepción de las estaciones cercanas al talud continental atlántico, las comunidades fuera del sistema de canales no se distinguieron mucho de las de dentro. No se evidenciaron diferencias faunísticas causadas por influencia pacífica o atlántica. Los patrones biológicos se pueden explicar mejor por los parámetros ambientales profundidad del agua, presencia de sedimentos blandos y escombros biogénicos

Spherical designs from norm-3 shell of integral lattices

A set of vectors all of which have a constant (non-zero) norm value in an Euclidean lattice is called a shell of the lattice. Venkov classified strongly perfect lattices of minimum 3 (R\'{e}seaux et "designs" sph\'{e}rique, 2001), whose minimal shell is a spherical 5-design. This note considers the classification of integral lattices whose shells of norm 3 are 5-designs.Comment: 10 pages, http://www2.math.kyushu-u.ac.jp/~j.shigezumi

Structure and dynamics of the fast lithium ion conductor "li 7La3Zr2O12"

The solid lithium-ion electrolyte "Li7La3Zr 2O12" (LLZO) with a garnet-type structure has been prepared in the cubic and tetragonal modification following conventional ceramic syntheses routes. Without aluminium doping tetragonal LLZO was obtained, which shows a two orders of magnitude lower room temperature conductivity than the cubic modification. Small concentrations of Al in the order of 1 wt% were sufficient to stabilize the cubic phase, which is known as a fast lithium-ion conductor. The structure and ion dynamics of Al-doped cubic LLZO were studied by impedance spectroscopy, dc conductivity measurements, 6Li and 7Li NMR, XRD, neutron powder diffraction, and TEM precession electron diffraction. From the results we conclude that aluminium is incorporated in the garnet lattice on the tetrahedral 24d Li site, thus stabilizing the cubic LLZO modification. Simulations based on diffraction data show that even at the low temperature of 4 K the Li ions are blurred over various crystallographic sites. This strong Li ion disorder in cubic Al-stabilized LLZO contributes to the high conductivity observed. The Li jump rates and the activation energy probed by NMR are in very good agreement with the transport parameters obtained from electrical conductivity measurements. The activation energy Ea characterizing long-range ion transport in the Al-stabilized cubic LLZO amounts to 0.34 eV. Total electric conductivities determined by ac impedance and a four point dc technique also agree very well and range from 1 × 10-4 Scm-1 to 4 × 10-4 Scm-1 depending on the Al content of the samples. The room temperature conductivity of Al-free tetragonal LLZO is about two orders of magnitude lower (2 × 10 -6 Scm-1, Ea = 0.49 eV activation energy). The electronic partial conductivity of cubic LLZO was measured using the Hebb-Wagner polarization technique. The electronic transference number te- is of the order of 10-7. Thus, cubic LLZO is an almost exclusive lithium ion conductor at ambient temperature. © the Owner Societies 2011

AKR1C1/2 inhibition by MPA sensitizes platinum resistant ovarian cancer towards carboplatin

In recurrent epithelial ovarian cancer (EOC) most patients develop platinum-resistance. On molecular level the NRF2 pathway, a cellular defense mechanism against reactive oxygen species, is induced. In this study, we investigate AKR1C1/2, target of NRF2, in a well-established EOC collective by immunohistochemistry and in a panel of ovarian cancer cell lines including platinum-resistant clones. The therapeutic effect of carboplatin and MPA as monotherapy or in combination was assessed by functional assays, using OV90 and OV90cp cells. Molecular mechanisms of action of MPA were investigated by NRF2 silencing and AKR activity measurements. Immunohistochemical analysis revealed that AKR1C1/2 is a key player in the development of chemoresistance and an independent indicator for short PFS (23.5 vs. 49.6 months, p = 0.013). Inhibition of AKR1C1/2 by MPA led to a concentration- and time-dependent decline of OV90 viability and to an increased response to CP in vitro. By NRF2 silencing, however, the effects of MPA treatment were reduced. Concludingly, our data suggest that a combination therapy of carboplatin and MPA might be a promising therapeutic approach to increase response rates of EOC patients, which should be explored in clinical context