Approximate belief updating in max-2-connected Bayes networks is NP-hard

A max-2-connected Bayes network is one where there are at most 2 distinct directed paths between any two nodes. We show that even for this restricted topology, null-evidence belief updating is hard to approximate.     

Pore formation,permeability, and permselectivity in porogen derived membranes

Porogen derived membranes, formed on decomposition of porogen molecules homogeneously dispersed in premembranes, were divided into two groups according to permeability and permeation mechanism. The more open membranes were formed when premembranes were cast on nonwoven polyester cloth support, or when decomposition products were extracted by solvent. The molecular cut off found for these membranes was at about 1000 Daltons and permeability was mainly determined by permeants' diffusivity and concentration. Permeability through the denser membrane was mainly determined by the permeants' partial vapor pressure, leading to high permselectivities. These denser membranes allowed relatively high osmotic water permeation while practically blocking permeation of solutes, such as salt, in the opposite direction. These membranes were thus also suitable for concentration of aqueous solutions by water removal into concentrated electrolyte solutions. © John Wiley & Sons, Inc.     

Saccadic Inhibition in Reading.

In 5 experiments, participants read text that was briefly replaced by a transient image for 33 ms at random intervals. A decrease in saccadic frequency, referred to as saccadic inhibition, occurred as early as 60-70 ms following the onset of abrupt changes in visual input. It was demonstrated that the saccadic inhibition was influenced by the saliency of the visual event (Experiment 3) and was not produced in response to abrupt but irrelevant auditory stimuli (Experiment 1). Display changes restricted to an area either inside or outside the perceptual span required for normal reading produced strong saccadic inhibition (Experiment 2). Finally, Experiments 4 and 5 demonstrated higher level cognitive or attentional modulation of the saccadic inhibition effect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Injection locking of a passively mode-locked laser

We present and analyze a model of a passively mode-locked laser, which is subjected to injection of a coherent pulse train. The model, based on soliton perturbation theory, predicts the possibility of coherent injection locking, and gives analytical estimates for the locking ranges. The ability to simultaneously lock the timing and the phase of the output pulses of a mode-locked laser to an injected, coherent pulse train is shown. The interesting limiting case of phase locking the mode-locked laser to a constant amplitude external injection, is addressed with implications for future coherent soliton communication systems     

Design of broad-band PMD compensation filters

We describe a new design approach for broad-band polarization-mode dispersion (PMD) compensation filters. An efficient algorithm for minimization of the maximum differential group delay within a given frequency band is described.     

A nanoscale parametric feedback oscillator

We describe and demonstrate a new oscillator topology, the parametric feedback oscillator (PFO). The PFO paradigm is applicable to a wide variety of nanoscale devices and opens the possibility of new classes of oscillators employing innovative frequency-determining elements, such as nanoelectromechanical systems (NEMS), facilitating integration with circuitry and system-size reduction. We show that the PFO topology can also improve nanoscale oscillator performance by circumventing detrimental effects that are otherwise imposed by the strong device nonlinearity in this size regime.     

Pyridine‐Modified Polymer as a Non‐Covalent Compatibilizer for Multi‐Walled CNT/Poly[ethylene‐co‐(methacrylic acid)] Composites Fabricated by Direct Melt Mixing

Multi‐wall CNT/poly[ethylene‐co‐(methacrylic acid)] composites were prepared by melt mixing. To improve dispersion and promote polymer/nanotube interactions, a novel non‐covalent compatibilizer is synthesized by reacting the polymer with 4‐(aminomethyl)pyridine. The composite based on the pristine polymer shows electrical and rheological percolation thresholds at nanotube loadings of 1.85 and 1.4 wt%, respectively. When 5 wt% of the pyridine‐modified compatibilizer is added, the corresponding values are reduced to 1.44 and 0.8 wt%, respectively. The electrical resistivity decreases even further as 10 wt% of the novel dispersing agent is used. Microscopy and Raman spectroscopy confirm the improved dispersion and π‐interactions established during melt mixing.

     

HYDROFLUORIC ACID EXTRACTION BY TBP AND BY AMINES: I. A CRITICAL REVIEW OF THE HF-H2O-EXTRACTANT SYSTEM

Literature on HF extraction by amines and by tributyl phosphate is critically reviewed. The system amine-HF-H₂O shows an interesting feature concerning properties such as distribution curves compared to those for extraction of other acids, similarity to extraction by TBP, water extraction, selectivity, effect of amine type and dilution and diluent effect These properties sharply change (or even invert) when HF/amine molar ratio exceeds 2.     

Influence of partial charge on the material removal rate during chemical polishing

A partial charge-based chemical polishing model has been developed, which can serve as metric for describing the relative polishing material removal rate for different combinations of slurries and workpieces. A series of controlled polishing experiments utilizing a variety of colloidal polishing slurries (SiO₂, CeO₂, ZrO_2, MgO, Sb₂O₅) and optical materials [single crystals of Al₂O₃ (sapphire), SiC, Y₃Al₅O₁₂ (YAG), CaF₂, and LiB₃O₅ (LBO); a SiO₂-Al₂O₃-P₂O₅-Li₂O glass ceramic (Zerodur); and glasses of SiO₂:TiO₂ (ULE), SiO₂ (fused silica), and P₂O₅-Al₂O₃-K₂O-BaO (Phosphate)] was performed and its material removal rate was measured. As previously proposed by Cook (J Non-Cryst Solids. 1990;120:152), for many polishing systems, the removal rate is governed by a series of chemical reactions which include the formation of a surface hydroxide, followed by condensation of that hydroxyl moiety with the polishing particle, and a subsequent hydrolysis reaction. The rate of condensation can often be the rate limiting step, thus it can determine the polishing material removal rate. By largely keeping the numerous other factors that influence material removal rate fixed (such as due to particle size distributions, interface interactions, pad topography, kinematics, and applied pressure), the material removal rate is shown to scale exponentially with the partial charge difference (δ_wp-s) between the workpiece and polishing slurry particle for many of the slurry-workpiece combinations indicating that condensation rate is the rate limiting step. The partial charge (δ) describes the equilibrium distribution of electron density between chemically bonded atoms and is related to the electronegativity of the atoms chemically bonded to one another. This partial charge model also explains the age-old experimental finding of why cerium oxide is the most effective polishing slurry for chemical removal of many workpieces. Some of the slurry-workpiece combinations that did not follow the partial charge dependence offer insight to other removal mechanisms or rate limiting reaction pathways.