Cross-phase-modulation-induced nonlinear phase noise in WDM direct-detection DPSK systems

In direct-detection differential-phase-shift-keying (DPSK) systems, the signal-spontaneous emission beat noise introduces phase noise due to Kerr nonlinearity. In wavelength-division-multiplexed (WDM) systems, this nonlinear phase noise comes not only from the channel itself through self-phase modulation (SPM) but also from the other channels through cross-phase modulation (XPM). In this paper, we theoretically and experimentally investigate XPM-induced nonlinear phase noise. We calculate the performance degradation of DPSK systems caused by XPM-induced nonlinear phase noise in addition to SPM-induced phase noise and experimentally verify it using a 600-km nonzero-dispersion-shifted-fiber link.     

A PLL clock generator with 5 to 10 MHz of lock range formicroprocessors

A microprocessor clock generator based on an analog phase-locked loop (PLL) is described for deskewing the internal logic control lock to an external system lock. This PLL is fully generated onto a 1.2-million-transistor microprocessor in 0.8-μm CMOS technology without the need for external components. It operates with a lock range from 5 to 110 MHz. The clock skew is less than 0.1 ns, with a peak-to-peak jitter of less than 0.3 ns for a 50-MHz system clock frequency     

An efficient assumed strain element model with six DOF per node for geometrically non-linear shells

The present paper describes an assumed strain finite element model with six degrees of freedom per node designed for geometrically non-linear shell analysis. An important feature of the present paper is the discussion on the spurious kinematic modes and the assumed strain field in the geometrically non-linear setting. The kinematics of deformation is described by using vector components in contrast to the conventional formulation which requires the use of trigonometric functions of rotational angles. Accordingly, converged solutions can be obtained for load or displacement increments that are much larger than possible with the conventional formulation with rotational angles. In addition, a detailed study of the spurious kinematic modes and the choice of assumed strain field reveals that the same assumed strain field can be used for both geometrically linear and non-linear cases to alleviate element locking while maintaining kinematic stability. It is strongly recommended that the element models, described in the present paper, be used instead of the conventional shell element models that employ rotational angles.     

Phase Transformations in Dicalcium Silicate: II, TEM Studies of Crystallography, Microstructure, and Mechanisms

The crystallography, microstructures, and phase transformation mechanisms in dicalcium silicate (Ca₂SiO₄) were studied by TEM. Three types of superlattice structures were observed in the α'_L and β phases. Almost all β grains were twinned and strained. Symmetry-related domain structures inherited from previous high-temperature transformations were observed in β grains. Both the α→α'_H and α'_L→β transformations were considered to be ferroelastic, and spontaneous strains were calculated. In terms of the crystal structures, the major driving force for the β→γ transformation is proposed to be strains and cation charge repulsions in the β structure. This mechanism can be displacive, but it needs to overcome a comparatively high energy barrier.     

Correlated response of udder dimensions to selection for milk yield in Holsteins

Response to selection for milk yield in Holsteins was examined by a controlled selection experiment initiated in 1964. Foundation cows were paired by sire and divided randomly into two breeding groups, selection and control. Selection group was mated to four sires each year highest for Predicted Difference milk. Twenty bulls selected in 1964 as near breed average for milk sired all control cows. Milk yield was recorded for each lactation, and height of udder from ground, distances between teats, and perimeter and area bound by the four teats were measured at 30 to 75 days postpartum on 153 selection and 202 control cows over 14 yr. Most estimates of repeatability and heritability of udder dimensions before and after milking were .45 or larger. Correlations with milk yield were negative for udder height and positive for other udder measurements. Selection cows exceeded controls for lactational milk yield. Daughters of high milk bulls had greater distances between teats, greater perimeters, and larger areas of udder floor. Selection cows did not differ from controls in udder height for first parity but were below controls in udder height and had udders that collapsed more for all parities.     

Genetic definition of a new bovine papillomavirus type 1 open reading frame, E5B, that encodes a hydrophobic protein involved in altering host-cell protein processing

We have previously observed that bovine papillomavirus type 1 (BPV-1) induces the appearance of five cellular proteins in C127 mouse fibroblasts, four of which appear to arise by altered processing of resident endoplasmic reticulum proteins. Studies of various cell lines revealed that expression of the 3' end of the BPV early region was sufficient for induction of these changes. To identify the BPV gene responsible, we have utilized the simian virus 40 (SV40)/BPV-1 recombinant virus Pava-1, which expresses the 3' end of the BPV early region behind an SV40 early promoter. C127 cells infected with Pava-1 for 48 h show the expected BPV-associated alterations, as do cells infected with Pava constructs mutated in the E5 or E2 genes. However, a mutation in the start codon of a previously ignored open reading frame extending from nucleotides 4013 to 4170 (E5B) eliminated the BPV-associated changes. Similar results were obtained with COS cells infected with the Pava mutants and C127 cells transformed by full-length mutated BPV. Despite its influence on the processing of cellular endoplasmic reticulum proteins, this mutation in E5B did not alter BPV-transforming efficiency or the ability of transformants to form colonies in soft agar. The E5B open reading frame encodes a hydrophobic 52-amino-acid polypeptide that shares structural similarities with HPV6 E5A and HPV16 E5. Speculations on a role for E5B in the viral life cycle are discussed.