Optical homodyne receiver with a six-port fibre coupler

The performance of a PSK optical homodyne system based on a six-port fibre coupler, which avoids the need for an optical 90° hybrid device, is determined. Depending on the actual receiver implementation using the coupler, the receiver sensitivity is shown to be about 0.5?3 dB from ideal and local laser excess intensity noise can be cancelled.     

Thermal behaviour of partially neutralised ethylene-maleic acid copolymer

As part of continuing studies on the cure of candidate polymers for waterborne coatings, the thermal behaviour of partially neutralised ethylene-maleic acid copolymer, EMA, has been examined. Films of EMA neutralised with a variety of bases were heated at 250°C. For this copolymer, as for poly(acrylic acid) at the same temperature, reflectance infrared spectroscopy has shown that heating led initially to anhydride formation. In the unneutralised state, or with the divalent ions calcium, magnesium, cobalt or zinc, further heating led to little or no further reaction. By contrast, the presence of univalent metal ions lithium, sodium and potassium caused a second reaction to occur, namely decarboxylation to yield keto crosslinks. This second reaction, however, did not occur to the extent that it does with poly(acrylic acid) under identical conditions. Possible reasons for this are discussed. Unlike poly(acrylic acid), EMA when partially neutralised was found not to form continuous films on the tin-plate substrate.     

Preliminary Results on an Approach for the Quantification of Lignin-Carbohydrate Complexes (LCC) in Hardwood Pulps

Abstract

The literature on biomass research contains many references to lignin-carbohydrate complexes (LCC) decreasing the rate of delignification in chemical pulp production, decreasing the yield of cellulosic ethanol via fermentation, and decreasing forage digestibility. However, it is difficult to find correlations between rates of the processes above and initial LCC concentration. One of the main reasons for the lack of such correlations is the absence of methods for accurate quantification of LCC. In this investigation, repeatable and reproducible determinations of bound sugars at monomeric concentrations as low as 0.3 wt% on enzymatic lignin (EL) have been achieved. The bound sugars are hydrolyzed by H₂SO₄, most likely as low molecular weight oligomers. In the same H₂SO₄ treatment, the oligomers are hydrolyzed to monomers which are subsequently quantified by ¹H NMR analyses. A significant enrichment of bound arabinan was previously reported when a crude milled wood lignin (MWL) was compared to the starting wood meal. A similar arabinan enrichment was observed for ELs from kraft and soda-AQ (SAQ) pulps in the present study. Also, well-resolved cross-peaks have been obtained in 2D HSQC NMR analyses of ELs. It has so far been confirmed that the EL from a 30.6 kappa number SAQ pulp from sugar maple contained ～30% more benzyl ethers linked to primary-OH groups in sugar units than the corresponding EL from a 33.7 kappa number kraft pulp.     

Medial dorsal thalamic lesions impair blocking and latent inhibition of the conditioned eyeblink response in rats.

The effects of lesions of the medial dorsal thalamic nucleus (MD) on blocking and latent inhibition (LI) of the rat eyeblink response were examined in the present study. Previous work has demonstrated that the cingulate cortex and related thalamic areas are involved in processing conditioning stimuli throughout training. The experiments in the present study tested the hypothesis that disruption of cingulothalamic stimulus processing produced by lesions of the MD would impair 2 types of associative learning that involve decremental changes in attention. In Experiment 1, MD lesions severely impaired blocking. In Experiment 2, NM lesions severely impaired LT. The results indicate that lesions of the NM impair incremental, decremental, or both types of changes in stimulus processing during learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ion formation in the flame ionization detector

The spatial distribution of positive ions in the flame ionization detector (FID) has been studied by a mass-spectrometric method. Except in the region well upstream from the flame front, the ions formed are the same for hydrocarbons, alcohols, and ketones. A mechanism is proposed for the formation of ions, which leads to the experimentally observed FID relationships connecting ionization with additive structure and concentration.     

Inverse method for identifying the underlying crack distribution in plates with random strengths

Summary In the current investigation we seek to identify the underlying crack number and crack length distributions in brittle plates with a known strength distribution. The inverse problem in probabilistic fracture mechanics is defined, and the numerical procedure to solve the inverse problem is constructed. The simulation process of generating simulated plates containing simulated random cracks is elaborated. The maximum strain energy release rate criterion (G _max) is applied to each simulated random crack to find the crack strength. The strength of the simulated plate is equated to the strength of the weakest simulated crack in the plate based on the weakest link notion. The underlying crack number and crack length distributions are obtained by minimizing the difference between the simulated plate strengths and the known plate strengths. The gamma, lognormal and two-parameter Weibull distributions are employed for the underlying crack length distribution, and are compared in order to identify the best choice. Numerical examples demonstrate that the three PDFs are all acceptable for reasons to be explained. In the appendix, the direct problem in probabilistic fracture mechanics is presented as part of the demonstration of a method for using the crack distribution identified in the inverse problem to predict the strength and the probability of fracture in a practical application.     

New technology, old issues: Demonstrating the relevance of the Canadian Code of Ethics for Psychologists to the ever-sharper cutting edge of technology.

New technology brings with it new opportunities for the practice of our profession. However, this technology is also a double-edged sword in that it can also cause problems for our profession and those we serve. The Canadian Code of Ethics for Psychologists (3rd edition) provides a foundation for approaching the issues that can arise in its use. It is argued that psychologists need not wait for specific rules and guidelines regarding the ethical use of new technologies; rather, psychologists can utilize the Canadian Code of Ethics for Psychologists immediately to address many of the issues involved. There is a wide range of areas in which ethical issues can arise. The focus in this paper is on three specific examples (online personal information accessibility, web-based advertising, and electronic data storage). These examples illustrate both the ethical issues involved and demonstrate the potential for how the Code can be used to think through and manage or resolve the issues. After a discussion of the three examples, the ongoing relevance of the Code to meeting the ethical challenges of continuously evolving technologies is discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Analysis and comparison of particle tribochargers

Triboelectric separation is a dry electrostatic particle processing technique. A ‘tribocharger’ is used to differentially charge particles of different materials by contact or friction. These are then separated by an electric field. There has been little analytical work done on tribocharger design, slowing the development of this promising technology. One problem is that the fundamental physics of bulk particulate tribocharging have hitherto been poorly understood. We have previously performed experimental and theoretical studies to characterise the charging of bulk particulates in dynamic contact with surfaces. Following from this, a number of tribocharger configurations (sliding trough, vibratory canister and pneumatic cyclone) have been studied and their charging performance and other key parameters compared. An overview of the important results so far is presented, and these are used to demonstrate a general approach to design of tribocharging devices.     

Influence of Acidity on the Electrostatic Stability of Alumina Suspensions in Ethanol

Alumina (Al₂O₃) powders have been dispersed in ethanol (EtOH) solutions of different acidity. In aqueous media, acidity is defined by pH. This definition can be extended to nonaqueous media using ion-transfer functions. The electrical charge on the particle surfaces has been found to be acidity dependent. The electrostatic stability of Al₂O₃EtOH suspensions has been evaluated via electrophoresis and turbidity. An electrostatic stabilization mechanism is proposed and analyzed via Derjaguin–Landau–Verwey–Overbeek (DLVO) theory.     

Lexical access and phonological decoding in adult dyslexic subtypes.

Lexical access and phonological decoding were tested in 100 normal adult readers and 21 adult dyslexic individuals. Within the dyslexic sample, 11 dysphonetic dyslexic and 10 dyseidetic dyslexic participants were classified on the basis of spelling patterns. In the 1st experiment, adult dyseidetic readers showed a marked deficit on the lexical-access decision task in comparison with adult dysphonetic readers. In the 2nd experiment, the phonological-decoding decision task did not separate the subtypes. A lexical-access deficit in adult dyseidetic dyslexia cannot be explained in terms of a developmental delay. A phonological-decoding deficit in adult dyseidetic dyslexia may be explained by increased involvement of the lexical procedure in phonological assembly under an analogy strategy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)