Myxomas of the mandible and maxilla

Two cases of congenital absence of a cervical vertebral pedicle are reported. This condition includes hypoplasia of the ipsilateral posterior arch and may predispose to spinal cord injury. The radiographic and computed tomography (CT) findings are reviewed, and the importance of the ipsilateral oblique radiographic view and of CT in diagnosis is stressed.     

Topological rigidity of semigroups of affine maps

We study the topological rigidity of affine semigroups of algebraic actions. In the first part of the paper we given an algebraic condition for rigidity that unifies previous rigidity results and we settle an old question of Walters. In the second part we study a generalized notion of the rigidity of hyperbolic actions.     

Infrastructure IP for configuration and test of boards and systems

Embedding infrastructure IP to optimize chip-level manufacturing test and debugging has recently become common practice. However, adopting the same approach for boards and systems requires a different family of infrastructure IP. This article introduces such a family and discusses how it can optimize manufacturing test and debugging, as well as support configurability, especially in today's reconfigurable products.     

Successful Aging

This issue's Works in Progress department presents six abstracts for projects that are developing interesting solutions to the elderly's quality of life challenges. The first two abstracts discuss projects that will help provide the elderly with freedom and independence by instrumenting their environments with supportive technology. The next two abstracts discuss projects building specialized user interfaces for addressing some of the challenges associated with aging, such as vision impairment. The final two abstracts present projects that will aid independence for the elderly by providing remote monitoring and assistance.     

Conducting polymers at low temperatures and high magnetic fields

Advances in the synthesis of organic conducting polymer systems has increased the electrical conductivity of these systems by several orders of magnitude in the last decade. Several practical applications are envisioned for such systems, but a thorough understanding of the conduction mechanisms and identification of the charge carriers is lacking, making design and implementation for bulk synthesis difficult. In order to clarify our understanding of the electrical properties of these systems, the resistivity and magnetoresistivity of various polymers doped near the metal - insulator transition, such as polyaniline protonated by camphor sulfonic acid (PANi-CSA) and polypyrrole doped with PF₆ (PPy-PF₆), have been studied down to 25 mK in magnetic fields up to 16 T.     

Effect of maturation on alpha-adrenoceptor activity in newborn piglet mesentery

To characterize the mesenteric alpha1- and alpha2-adrenoceptor populations in newborn piglets, an extracorporeal circuit was established to control intestinal blood flow in 0- to 2-day old and 10- to 14-day old animals. In both groups, alpha-adrenoceptor activation was first documented by observing dose-dependent increases in mesenteric perfusion pressure after intramesenteric arterial injection of alpha-adrenoceptor agonists. In the 10- to 14-day old piglets, mesenteric vasoconstrictor responses to alpha1-adrenoceptor agonists (methoxamine and norepinephrine) and an alpha2-adrenoceptor agonist (BHT-933) were each blunted (P < 0.05, analysis of variance) by peripheral intravenous injections of prazosin (an alpha1-adrenoceptor antagonist) and yohimbine (an alpha2-adrenoceptor antagonist), respectively. The mesenteric vasoconstrictor responses to those agonists were not significantly attenuated by prazosin or yohimbine in 0- to 2-day old animals, nor were they blunted by YM-12617 (alpha1-adrenoceptor antagonist) or idazoxan (alpha2-adrenoceptor antagonist)--compounds that are structurally unrelated to prazosin and yohimbine, respectively. In addition, mesenteric vasoconstrictor responses to other known vasoconstrictor agents--angiotensin II, neuropeptide Y, and a thromboxane A2 mimic (U-46619)--were not effected in either age group by prazosin or yohimbine, implying these agents act independently of alpha-adrenoceptor mechanisms. These data suggest that (1) there exists functional mesenteric alpha1- and alpha2-adrenoceptor-like activity in 10- to 14-day old piglets that, in 0- to 2-day old animals, is not specifically expressed; and (2) mesenteric alpha-adrenoceptor function becomes more selective as newborn piglets mature.