Fundamental properties of radiation from a leaky mode excited on a planar transmission line

By using a specific normalization, it is shown that the TM/sub 0/ radiation field from a leaky mode that is excited by a source on any printed-circuit structure can be represented in a unified manner. The general properties of the normalized leaky-mode radiation field are examined in detail for a variety of phase and attenuation constants, as well as distances from the source, and for different types of source excitations. The normalized leaky-mode radiation field is compared to similarly normalized geometrical-optics and far-field radiation expressions to provide further insight into the nature of the radiation fields in the near- and far-field regions. The results provide a general view of leaky-mode radiation properties independent of the type of planar transmission line or background structure.     

On finding optimal and near-optimal lineal spanning trees

The search for good lineal, or depth-first, spanning trees is an important aspect in the implementation of a wide assortment of graph algorithms. We consider the complexity of findingoptimal lineal spanning trees under various notions of optimality. In particular, we show that several natural problems, such as constructing a shortest or a tallest lineal tree, are NP-hard. We also address the issue of polynomial-time, near-optimization strategies for these difficult problems, showing that efficient absolute approximation algorithms cannot exist unlessP = NP.This author's research was supported in part by the Sandia University Research Program and by the National Science Foundation under Grant M IP-8603879.This author's research was supported in part by the National Science Foundation under Grants ECS-8403859 and MIP-8603879.     

On finding optimal and near-optimal lineal spanning trees

The search for good lineal, or depth-first, spanning trees is an important aspect in the implementation of a wide assortment of graph algorithms. We consider the complexity of findingoptimal lineal spanning trees under various notions of optimality. In particular, we show that several natural problems, such as constructing a shortest or a tallest lineal tree, are NP-hard. We also address the issue of polynomial-time, near-optimization strategies for these difficult problems, showing that efficient absolute approximation algorithms cannot exist unlessP = NP.     

Long latency postural reflexes are under supraspinal dopaminergic control

Scaling of posturally stabilizing long latency (LL) reflexes in tibialis anterior muscles induced by "toe-up" rotational perturbations is abnormal in standing patients with Parkinson's disease. To investigate the contribution of dopaminergic pathways to abnormal scaling, we studied LL reflexes in 22 patients with selective hypodopaminergic syndromes: 10 psychiatric patients taking chronic neuroleptic medication (7 with mild parkinsonism), 8 patients with young-onset Parkinson's disease, and 4 patients with MPTP-induced parkinsonism. Results were compared with those of 10 healthy controls. Stimuli consisted of (a) 10 serial (predictable) perturbations of 4 degrees amplitude, (b) 10 serial (predictable) perturbations of 10 degrees amplitude, and (c) 20 randomly mixed (unpredictable) perturbations of either 4 or 10 degrees amplitude. In normal subjects, LL reflex amplitudes were adapted to match predictable variations in stimulus size, whereas under unpredictable conditions a "default" response emerged that anticipated the 10 degrees perturbation. LL reflex scaling under predictable conditions was intact in patients with neuroleptic-induced parkinsonism and young-onset Parkinson's disease, but the large default LL response under unpredictable conditions was absent. In patients with MPTP-induced parkinsonism, LL reflex scaling was absent during both predictable and unpredictable conditions. We conclude that abnormal scaling of posturally stabilizing LL reflexes is related to decreased supraspinal dopaminergic influence.     

Scalable Parallel Algorithms for FPT Problems

Algorithmic methods based on the theory of fixed-parameter tractability are combined with powerful computational platforms to launch systematic attacks on combinatorial problems of significance. As a case study, optimal solutions to very large instances of the NP-hard vertex cover problem are computed. To accomplish this, an efficient sequential algorithm and various forms of parallel algorithms are devised, implemented, and compared. The importance of maintaining a balanced decomposition of the search space is shown to be critical to achieving scalability. Target problems need only be amenable to reduction and decomposition. Applications in high throughput computational biology are also discussed.     

Life tasks, self-concept ideals, and cognitive strategies in a life transition.

This paper reports on data from a longitudinal study in which normative life tasks and individuals' personal versions of those tasks are investigated in the context of students making the transition from home and high school to college life. Analyses focus both on common patterns of life-task appraisal in interpersonal and achievement domains and on differences in the self-concepts and cognitive strategies that individual students bring to bear as they confront these normative pressures (Cantor & Kihlstrom, 1987). In particular, we investigate the impact of students' actual-ideal self-discrepancies (Higgins, Klein, & Strauman, 1985) on subjective stress and satisfaction in achievement and interpersonal life-task domains and suggest that self-concept discrepancy negatively affects adjustment in the achievement domain and positively affects social outcomes. Students using a defensive-pessimism strategy motivated themselves by confronting their anxieties in advance of stressful tasks, whereas those using an optimistic strategy assumed the best until proved otherwise—protecting self-esteem after the fact in the event of disappointment (Norem & Cantor, 1986a, 1986b). This analysis, thus, begins at the level of normative "readings" of life tasks in a shared transition period and gradually moves toward consideration of how individuals navigate those tasks in personally meaningful ways. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Identification of a RAPD marker linked to progressive rod-cone degeneration in dogs

1. Tammar Wallaby embryonic blood has been shown to have three alpha-like and two beta-like globin chains in its four haemoglobin components and partial sequences of several chains have been determined. 2. The major embryonic beta-like chain (epsilon) is similar to other mammalian embryonic beta-like chains on the basis of sequencing its first 60 amino acids. 3. There is another embryonic beta-like chain present in one haemoglobin component. It was designated omega and, in its first 54 amino acids, it has features that are more like avian globins than mammalian globins. 4. The one alpha-like embryonic globin sequenced has mammalian rather than avian characteristics. 5. A provisional phylogenetic tree of beta-like globins has been determined. The Tammar epsilon-globin forms a monophyletic group with marsupial and other mammalian embryonic globins; the omega-globin forms a monophyletic group with bird adult and embryonic globins.