This paper reviews spur reduction techniques used in direct digital synthesizers (DDSs) or numerically controlled oscillators (NCOs). First, the classification and operation of conventional DDSs are reviewed. Covered are the pulse output DDS, sine output DDS, fractional divider, and phase interpolation DDS. It is shown that DDSs produce spurs as well as the desired output frequency due to the a...

For over two centuries, the platypus (Ornithorhynchus anatinus) has been constructed and categorized in multiple ways. An unprecedented mélange of anatomical features and physiological functions, it long remained a systematic quandary. Nevertheless, since 1797, naturalists and biologists have pursued two recurring obsessions. Investigations into platypus reproduction and lactation have focused ...

The main purpose of this paper was to evaluate the performance of the triangular vanes located on the bed and their effect on the bed topography considering different flow conditions. For this purpose, tests were carried out on a straight flume for different flow conditions (five Froude numbers of 0.18, 0.20, 0.22, 0.24 and 0.26) by installing a series of triangular vanes at a space of 4Le (Le ...

We describe asymmetrical features in a long exposure X-ray map of M87 made with the ROSAT High Resolution Imager (HRI). A bright triangular region is marked by a linear 'spur' along one edge. The structure of this spur suggests an interpretation of a tangential view of a shock front 18 kpc long. None of the brighter features are spatially coincident with radio or optical structures so we concur...

The morphology of the outflow apparatus in human eyes which had been treated topically with either 2 or 4% pilocarpine on 4 occasions at 6-hourly intervals before enucleation was compared with an untreated control series of eyes from patients in a similar age range. In the pilocarpine-treated group the scleral spur was pulled posteriorly and internally, so that the angle formed by the scleral s...

By enforcing specific pollinator interactions, Aquilegia petal nectar spurs maintain reproductive isolation between species. Spur development is the result of three-dimensional elaboration from a comparatively two-dimensional primordium. Initiated by localized, oriented cell divisions surrounding the incipient nectary, this process creates a pouch that is extended by anisotropic cell elongation...

PURPOSE To study the innervation of the aqueous outflow channels and scleral spur by autonomic nerves containing substance P. METHODS The experiments were conducted on guinea pigs. Immunohistochemical techniques and capsaicin-ablation of the sensory nerves were used to investigate nerves containing substance P at the light and electron microscopic level. RESULTS Nerves containing substance ...

A hybrid zone involving the deep-sea mussels, Bathymodiolus azoricus and B. puteoserpentis, was recently discovered at Broken Spur hydrothermal vent field (29 degrees 10' N, 43 degrees 10' W) along an intermediate segment of the Mid-Atlantic Ridge axis. Examination of nuclear (allozymes) and cytoplasmic (mitochondrial DNA) gene markers in a new sample from Broken Spur revealed significant cyton...

Isometric modification is proposed as a new method of axial modification of spur bevel gear. Based on the gear geometry theory and the normal meshing motion equation of gear pairs, changes of meshing points and angles are analyzed and the effect of axial modification on meshing movement of gear pairs is discussed. After that, a method of drawing spherical involute with the aid of SolidWorks sof...