Chirping-induced waveform distortion in 2.4-Gb/s lightwavetransmission systems

The performance of high-speed lightwave transmission systems operating in the 1.55-μm-wavelength region with conventional single-mode optical fiber can be influenced by the dynamic wavelength chirping exhibited by directly modulated semiconductor lasers. In a recent paper (1989), the authors presented the first detailed analysis of the bit error ratio performance of lightwave systems influenced by chirping-induced waveform distortion. Here, additional numerical results which address the performance implications of the waveform distortion by considering the dependence of the receiver sensitivity on the decision time and decision threshold, the eye pattern, and bit error rate ratio pattern are presented. It is shown that the response of the linear receiver filter can influence the dependence of the receiver sensitivity on the decision time     

Sorption behaviour of Triton X-1OOR surfactant by sand

Dynamic sorption data are reported for the system Triton X-100^R solutions and characterised sands. The sand was in the form of a consolidated sand pack in an attempt to model reservoir conditions. The dynamic isotherms were determined directly for experimental data using the Wilson and DeVault equations. The effect of dispersion was evaluated and the application of the data to enhanced oil recovery discussed. It is shown that the dynamic adsorption isotherm exhibits Langmuir type behaviour up to the c.m.c. whereas results from static measurements of sorption do not. In spite of dispersion being present it was found that the Wilson and DeVault equations predicted the rate of movement of a surfactant band to 1% accuracy.     

Mechanistic aspects of organotin stabilization of PVC

Prompted by commercial significance and academic interest, extensive model compound and in-situ studies of PVC degradation/stabilization appear in the literature. This paper presents the results of some in-situ studies of the chemical reaction pathways undergone by organotin thioglycollate esters during PVC stabilization. Infrared spectroscopy indicates that in the case of diocyltin bis(isooctylthioglycollate), not only is the mercaptoester/chloride generated, but also the corresponding thioglycollate (Oct₂ Sn TG). The extent to which this species is observed is dictated by the processing technique. An attempt is made to correlate the chemical reaction pathway of the organotin compounds with the changes (unsaturation) within the polymer. The possible relevance of these observations to the phenomenon of mono/di synergism is also discussed. While these studies extend our knowledge of the organotin stabilization of PVC, they also show that our understanding is far from complete.     

X-Ray Investigation of Strain in Cold-Worked Silver Iodide

The experimentally observed broadening of certain powder diffraction profiles of cold-worked hexagonal silver iodide has been graphically resolved into the effects due to small domain size and to lattice strain. The contribution from the first was found to be negligible, and the total intrinsic broadening is thus due to strain. A maximum, or saturation value, of strain is rapidly attained and remains invariant with further grinding. The strain is essentially isotropic, with an average value of 4.4×10⁻³. The calculated stored elastic energy is 154 cal/mole and, by comparison with the calculated difference in lattice energies of 149 cal/mole, can be interpreted as an energy barrier for the phase transition from the cubic to hexagonal structure.     

Rel revealed: cocrystal structures of the NF-kappa B p50 homodimer

24 model rabbits with femoral arterial thrombosis were divided into two groups: the treatment group consisting of 12 rabbits which received API0134, and the control group composed of another 12 rabbits. 2 hours after recanalization by urokinase thrombolysis, reocclusion occurred only in 1/12 vessel (8%) with incomplete occlusion in the treated group, but in 8/12 (67%) with complete occlusion in the control group as assessed by angiograsphy. Pathological examination of specimen taken 24 hours after thrombolysis showed that 6/12 (50%) of the treated group gave the evidence of thrombus occlusion, and milder intimal injury and less adhered blood cells than in the control group, 83% of which had thrombus occlusion. In comparision with the control group, the function of platelet in the treated group demonstrated lower platelet aggregation rate (PAgR) and plasma thromboxane A2 (TXA2) level, higher prostacyclin (PGI2) and plasminogen activator (PA) activity as well as lower plasminogen activator inhibitor (PAI) activity. From the above it may be concluded that the preventive effect of API0134 on reocclusion might be due to inhibition of platelets aggregation and promotion of fibrinolysis.     

The numerical solution of two-dimensional,steady flow problems by the finite element method

Finite element equivalents of the equations governing shearing and buoyancy driven flows are derived, and reduced to upwind forms suitable for the solution of problems in which the Reynolds and Rayleigh numbers are large. A modification to the central difference iterative method is studied which increases the Reynolds and Rayleigh numbers for which a central difference form may be used. A comparison is made between the results obtained using the central and upwind forms of the finite element method and those predicted by finite difference methods in the case of flow in a cavity. A mesh refinement study is made. The upwind forms of the finite element equations are applied to the solution of a complex flow problem involving the flow of glass in a throated furnace in the case of constant- and temperature- dependent viscosity and conductivity.     

Systems Silver Iodide-Sodium Iodide and Silver Iodide-Potassium Iodide

The phase relations for the systems AgI-NaI and AgI-KI have been determined for the temperature range from room temperature to 685° C, using differential thermal analysis techniques. The AgI-NaI system has a eutectic at 50 mole percent NaI and 384° C. The AgI-KI system has eutectics at 20.8 and 28.5 mole percent KI and 254° C and 244° C, respectively. A compound of formula KAg₃I₄ is formed with a congruent melting point of 268° C.     

Stress dependent behaviour of a particulate material

This paper considers the non-linear stress-strain characteristics of a particulate material using the classical elasticity concepts of modulus of elasticity and Poisson's ratio and shows that these terms are stress-dependent. In addition to the first loading of the material a number of unloading/reloading cycles are carried out under conditions representative of practical loading cases. Finally, recommendations are made regarding the analysis of problems involving particulate materials subjected to three-dimensional stress and strain.     

The Interval-Enhanced GNU Fortran Compiler

Compiler support for intervals as intrinsic data types is essential for promoting the development and wide-spread use of interval software. It also plays an important role in encouraging the development of hardware support for interval arithmetic. This paper describes modifications made to the GNU Fortran Compiler to provide support for interval arithmetic. These modifications are based on a recently proposed Fortran 77 Interval Arithmetic Specification, which provides a standard for supporting interval arithmetic in Fortran. This paper also describes the design of the compiler's interval runtime libraries and the methodology used to test the compiler. The compiler and runtime libraries are designed to be portable to platforms that support the IEEE 754 floating point standard.