Completing causal networks by meta-level abduction

Meta-level abduction is a method to abduce missing rules in explaining observations. By representing rule structures of a problem in a form of causal networks, meta-level abduction infers missing links and unknown nodes from incomplete networks to complete paths for observations. We examine applicability of meta-level abduction on networks containing both positive and negative causal effects. Such networks appear in many domains including biology, in which inhibitory effects are important in several biological pathways. Reasoning in networks with inhibition involves nonmonotonic inference, which can be realized by making default assumptions in abduction. We show that meta-level abduction can consistently produce both positive and negative causal relations as well as invented nodes. Case studies of meta-level abduction are presented in p53 signaling networks, in which causal relations are abduced to suppress a tumor with a new protein and to stop DNA synthesis when damage has occurred. Effects of our method are also analyzed through experiments of completing networks randomly generated with both positive and negative links.     

Magnetic relaxation rates in spin-polarized hydrogen

A self-contained discussion is presented of the longitudinal (T ₁ ^–1 ) and transverse (T ₂ ^–1 ) relaxation rates in bulk and surface samples of spin-polarized atomic hydrogen (H), at sufficiently low temperatures that only the lowest two atomic hyperfine levels are thermally populated. The nonhydrodynamic contribution to the rates, due to binary collisions between hydrogen atoms, in both normal and Bose condensed samples of H are emphasized. However, the approach is general and is equally well suited for treating long-wavelength, hydrodynamic relaxation processes. Most of the discussion pertains to samples close to thermodynamic equilibrium. The calculation of the longitudinal relaxation rate for some states far from equilibrium, particularly relevant for real samples of H, is also presented. Some of the interesting results are:(1) the potentially long surface longitudinal relaxation time (T ₁) in samples with most of the available surface area oriented perpendicular to the direction of the stabilizing field; (2) the possibility of extracting the condensate fractionn _o(T)/n from aT ₁ measurement in the Bose condensed state, and finally (3) an amusingGedanken experiment that would allow us to detect the onset of Bose condensation in aT ₁ measurement in the absence of recombination.     

Fast Ray Tracing of Implicit Surfaces

A ray-tracing algorithm is described for rendering implicit surfaces formed with C¹-continuous bounded functions f ( x , y , z ). This class of functions includes such popular implicit models as blobby molecules, metaballs, soft objects and convolution surfaces. The algorithm employs analytical methods only, which makes it fast, robust, and numerically stable.
An earlier version of this work was presented at the 3rd International Workshop on Implicit Surfaces held in Seattle in 1998.     

Scaling Properties of Superfluid 3He in Aerogel

We have investigated the superfluid transition of ³ He in different samples of silica aerogel. Several of these samples have been characterized using x-ray imaging, yielding information about the microstructure of the aerogel. In comparing new measurements on a 99.5% sample with previous observations on the behavior of ³ He in 98% porous aerogel we have found evidence for a scaling of the superfluid transition temperature to the correlation length of the aerogel. Furthermore, the superfluid density exhibits a similar universal behaviour over a range of values of reduced temperature. We discuss these new results in the context of superfluid pairing in the presence of a correlated disorder, specifically focussing on the fractal nature of the aerogel.     

刀具与工业4.0融合助力生产更高效

如同其他刀具制造商,模具制造对于伊斯卡而言也是重要的客户群体之一.这一工业分支不仅消耗了越来越多的刀具,而且对其不断提出新的要求,对推进刀具的技术进步产生了重大影响.这些要求对所有机加工领域来说都非常典型:客户总是对生产率更高、更可靠和更高精度的刀具感兴趣.然而,因模具制造的特殊性使其较一般需求更要做出特殊设计考量.     

A Novel Photoswitchable Azobenzene-Containing Local Anesthetic Ethercaine with Light-Controlled Biological Activity In Vivo

Pain is a common symptom that impairs the quality of life for people around the world. Local anesthetics widely used for pain relief have a number of side effects, which makes the development of both new drugs and new ways to control their activity particularly important. Photopharmacology makes it possible to reduce the side effects of an anesthetic and control its biological activity in the body. The purpose of this work was to create a new light-controlled local anesthetic and study its biological activity in animals. A compound with a simple scheme of synthesis was chosen to shift the UV-Vis absorption band towards the visible range of the spectrum and was synthesized for the first time. Some computer calculations were performed to make sure that the aforementioned changes would not lead to loss of biological activity. The micellar form of the new compound was prepared, and in vivo biological studies were carried out in rabbits. The existence of a local anesthetic effect, which disappeared almost completely on irradiation with light (λ = 395 nm), was shown using the surface anesthesia model. Moreover, the possibility of multiple reversible changes in the biological activity of ethercaine under the action of light was demonstrated. The latter compound manifests no local irritating effect, either. The data obtained indicate the prospects for the development of new compounds based on azobenzene for light-controlled local anesthesia.     

Effective cleaning of hexagonal boron nitride for graphene devices

Hexagonal boron nitride (h-BN) films have attracted considerable interest as substrates for graphene. ( Dean, C. R. et al. Nat. Nanotechnol. 2010 , 5 , 722 - 6 ; Wang, H. et al. Electron Device Lett. 2011 , 32 , 1209 - 1211 ; Sanchez-Yamagishi, J. et al. Phys. Rev. Lett. 2012 , 108 , 1 - 5 .) We study the presence of organic contaminants introduced by standard lithography and substrate transfer processing on h-BN films exfoliated on silicon oxide substrates. Exposure to photoresist processing adds a large broad luminescence peak to the Raman spectrum of the h-BN flake. This signal persists through typical furnace annealing recipes (Ar/H(2)). A recipe that successfully removes organic contaminants and results in clean h-BN flakes involves treatment in Ar/O(2) at 500 °C.     

Efficiency of naphthalene biodegradation by Pseudomonas putida G7 in soil

The efficiency of naphthalene degradation by Pseudomonas putida G7 in soil was assessed using a mathematical model. The number of microorganisms and the concentration of naphthalene in soil samples were monitored. The feasibility of a spectrofluorometric method for naphthalene assay in soil samples was compared with high pressure liquid chromatography. A proposed mathematical model described the growth of the naphthalene‐degrading strains and the consumption of substrates (naphthalene, naphthalene degradation intermediates and soil organic substances) in soil. To describe the growth kinetics of microorganisms having high affinity to substrates with low solubility, two differential equations with substrate exponent 2/3 were proposed. These equations were used to describe utilization of soil organic matter. The model parameters characterize the growth rates for different substrates and respective yield coefficients, specific bacterial death and adaptation rates, and also the rates of PAHs degradation and evaporation. These characteristics can be used in choosing the bacterial strains for biopreparations and efficient clean‐up biotechnology of polluted soils. Copyright © 2004 Society of Chemical Industry