\Lambda-buildings and base change functors

We prove an analog of the base change functor of \Lambda-trees in the setting of generalized affine buildings. The proof is mainly based on local and global combinatorics of the associated spherical buildings. As an application we obtain that the class of generalized affine building is closed under ultracones and asymptotic cones. Other applications involve a complex of groups decompositions and fixed point theorems for certain classes of generalized affine buildings.Comment: revised version, 29 pages, to appear in Geom. Dedicat

Degenerations of ideal hyperbolic triangulations

Let M be a cusped 3-manifold, and let T be an ideal triangulation of M. The deformation variety D(T), a subset of which parameterises (incomplete) hyperbolic structures obtained on M using T, is defined and compactified by adding certain projective classes of transversely measured singular codimension-one foliations of M. This leads to a combinatorial and geometric variant of well-known constructions by Culler, Morgan and Shalen concerning the character variety of a 3-manifold.Comment: 31 pages, 11 figures; minor changes; to appear in Mathematische Zeitschrif

Activity of different desoximetasone preparations compared to other topical corticosteroids in the vasoconstriction assay

Introduction: We report on a double-blind, vehicle-controlled, single-center confirmatory study with random assignment. The purpose of the study was to investigate the topical bioavailability of different topical corticosteroid formulations in healthy human beings focussing on desoximetasone (DM). Materials and Methods: Two DM 0.25% formulations {[}ointment (DM-o) and fatty ointment (DM-fo, water-free); class III corticosteroids], the corresponding active ingredient-free vehicles and three comparators of different strength {[}clobetasol propionate 0.05% (CP 0.05%), fatty ointment, class IV; hydrocortisone (HC) 1%, fatty ointment, class I, and betamethasone (BM) 0.05%, fatty ointment, class III] were tested using the vasoconstriction assay. The degree of vasoconstriction (blanching) in the treatment field was compared to the one found in untreated control fields using chromametric measurements and clinical assessment. Results/Conclusion: DM-o 0.25%, DM-fo 0.25% and BM 0.05% showed similar vasoconstrictive potential, i.e., clear blanching. In fact, both DM preparations were proven to be non-inferior to BM 0.05%, while CP 0.05% was found a little less active. HC 1.0% and the DM vehicles showed no clear-cut vasoconstrictive effect. No adverse events related to the study medications were observed. Good topical bioavailability of both DM formulations was detected by chromametric measurement and clinical assessment. Copyright (C) 2008 S. Karger AG, Basel

Strength Reduction in Electrical and Elastic Networks

Particular aspects of problems ranging from dielectric breakdown to metal insu- lator transition can be studied using electrical o elastic networks. We present an expression for the mean breakdown strength of such networks.First, we intro- duce a method to evaluate the redistribution of current due to the removal of a finite number of elements from a hyper-cubic network of conducatances.It is used to determine the reduction of breakdown strength due to a fracture of size $\kappa$.Numerical analysis is used to show that the analogous reduction due to random removal of elements from electrical and elastic networks follow a similar form.One possible application, namely the use of bone density as a diagnostic tools for osteorosporosis,is discussed.Comment: one compressed file includes: 9 PostScrpt figures and a text fil

NEUTRON-FLUX MEASUREMENTS IN A FLAT PLATE FUEL ELEMENT

The equipment and experiments performed to measure the thermal-neutron- flux distribution in a fuel assembly of an experimental loop mock-up of a gas:cooled reactor at the Battelle Research Reactor (BRR) are described. The loop was located adjacent to the core of the BRR and contained one fuel assermbly composed of seven flat fuel plates each containing approximately 29.5 g of U/sup 235/. The plates consisted of a core 0.050 in. thick of UO/sub 2/ dispersed in Type 347 stainless steel and clad on each side with 0.005 in. of Type 347 stainless steel. The measurements showed that with the present design of the loop system an average thermal-neutron flux of 4.09 x 1O/sup 12/ neutrons/(cm/sup 2/)(sec) or a power generation of 45 kw in the assembly can be conveniently obtained. The ratio of the peak thermal-neutron flux to average thermal flux in the entire element was found to be 1.87. At any horizontal cross section, thermal-flux depression from the edge of the element to the center of less than a factor of two was observed for the final loopcore arrangement. (auth

The incorporation of fungal to bacterial ratios and plant ecosystem effect traits into a state-and-transition model of land-use change in semi-arid grasslands

Feedbacks between plants, microbes and their growth traits are important in the maintenance of nutrient cycling functions. Despite this, there is little understanding of the role of these relationships in the transitions between alternate vegetation states in semi-arid and arid lands. We investigated the relationships between vegetation, soil nutrients and soil microbes across grasslands and agricultural fields described within an existing conceptual state-and-transition model of agricultural de-intensification in the semi-arid Riverine Plains grasslands of south-eastern Australia. Sites represented the proposed transition from annual exotic pastures to native perennial grasslands with agricultural de-intensification. Microbial community composition was assessed using phospholipid fatty acid analysis (PLFA). The native grassland state and the native pasture state were characterized by a higher fungal to bacterial ratio (F:B). The native grassland state had a slightly lower bacterial PLFA biomass whilst the native pasture state had a slightly higher fungal PLFA biomass, although these differences were non-significant. Only the recently cultivated, heavily grazed state was characterized by high soil nutrient availability (soil P and K) and leaf traits indicating rapid growth and resource utilization (high SLA, low LDMC). Thus, the association of these ecosystem properties with a lower F:B was not as close as expected. States with a higher F:B were not characterized by higher total soil C or C:N as hypothesized. This study further extends our knowledge of the association between fungal dominance and agricultural de-intensification to a semi-arid system with relatively old, nutrient poor soils. It highlights the need for a better understanding of the mechanistics behind this association and the implications for C cycling and storage in such systems.Megan R. Wong, John W. Morgan, Nathan K. Wong, Timothy R. Cavagnar

B2.5-Eunomia simulations of Magnum-PSI detachment experiments: I. Quantitative comparisons with experimental measurements

Detachment experiments have been carried out in the linear plasma device Magnum-PSI by increasing the gas pressure near the target. In order to have a proper detailed analysis of the mechanism behind momentum and power loss in detachment, a quantitative match is pursued between B2.5-Eunomia solutions and experimental data. B2.5 is a multi fluid plasma code and Eunomia is a Monte Carlo solver for neutral particles, and they are coupled together to provide steady-state solution of the plasma and neutral distribution in space. B2.5-Eunomia input parameters are adjusted to produce a close replication of the plasma beam measured in the experiments without any gas puffing in the target chamber. Using this replication as an initial condition, the neutral pressure near the plasma beam target is exclusively increased during simulation, matching the pressures measured in the experiments. Reasonable agreement is found between the electron temperature of the simulation results with experimental measurements using laser Thomson scattering near the target. The simulations also reveal the effect of increased gas pressure on the plasma current, effectively reducing the current penetration from the plasma source. B2.5-Eunomia is capable of reproducing detachment characteristics, namely the loss of plasma pressure along the magnetic field and the reduction of particle and heat flux to the target. The simulation results for plasma and neutrals will allow future studies of the exact contribution of individual plasma-neutral collisions to momentum and energy loss in detachment in Magnum-PSI.</p

Using Nonlinear Response to Estimate the Strength of an Elastic Network

Disordered networks of fragile elastic elements have been proposed as a model of inner porous regions of large bones [Gunaratne et.al., cond-mat/0009221, http://xyz.lanl.gov]. It is shown that the ratio $\Gamma$ of responses of such a network to static and periodic strain can be used to estimate its ultimate (or breaking) stress. Since bone fracture in older adults results from the weakening of porous bone, we discuss the possibility of using $\Gamma$ as a non-invasive diagnostic of osteoporotic bone.Comment: 4 pages, 4 figure

Asymptotically cylindrical 7-manifolds of holonomy G_2 with applications to compact irreducible G_2-manifolds

We construct examples of exponentially asymptotically cylindrical Riemannian 7-manifolds with holonomy group equal to G_2. To our knowledge, these are the first such examples. We also obtain exponentially asymptotically cylindrical coassociative calibrated submanifolds. Finally, we apply our results to show that one of the compact G_2-manifolds constructed by Joyce by desingularisation of a flat orbifold T^7/\Gamma can be deformed to one of the compact G_2-manifolds obtainable as a generalized connected sum of two exponentially asymptotically cylindrical SU(3)-manifolds via the method given by the first author (math.DG/0012189).Comment: 36 pages; v2: corrected trivial typos; v3: some arguments corrected and improved; v4: a number of improvements on presentation, paritularly in sections 4 and 6, including an added picture