Applications of differential forms to boundary integral equations

In this paper we discuss the application of differential forms to integral equations arising in the study of electromagnetic wave propagation. The usual Stratton-Chu integral equations are derived in terms of differential forms and corresponding Galerkin formulations are constructed. All numerical schemes require the specification of basis functions and the use of differential forms provides a very general method for the construction of arbitrary order basis functions on curvilinear geometries. It is noted that the lowest order approximations on flat geometries reduce to forms essential equivalent to the standard Rao-Wilton-Glisson functions. The effect on accuracy is investigated for electric field integral equation and magnetic field integral equation formulations for a range of bases. Hierarchical classes of functions are also developed, as are transition elements useful in p-adaptive schemes where variable orders of approximation are sought.     

Autobiographical remembering and hypermnesia: A comparison of older and younger adults.

This study examined age differences in autobiographical memory and extended findings concerning hypermnesia in laboratory tasks to a real world event, the announcement of the verdict in the O. J. Simpson murder trial. Older and younger adults repeatedly recalled the event in a single session. Interviews were coded for amount and type of accurate information and for errors. The age groups did not differ in ability to recall the gist of the event or in the number of errors made. Younger adults were better at remembering when the event had occurred. Both age groups showed hypermnesia. The results are discussed in terms of the importance of autobiographical memory across the life span and the phenomenon of hypermnesia in everyday memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Extending the study of autobiographical memory: Thinking back about life across the life span.

By combining a life perspective with a life span perspective, the authors present a basic framework for extending the study of autobiographical memory. The life perspective suggests not only the consideration of individual episodes of memory but how they are strung together into a life. The life span perspective takes into account the chronological age and life context of individuals and how these factors might affect abilities and motivations related to the use of autobiographical memory. The authors discuss how these 2 perspectives are combined to yield a useful framework for studying autobiographical memory and present 2 examples of work done using this framework. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Changes in integrative complexity accompanying significant life events: Historical evidence.

Integrative complexity is a state cognitive style variable characterized by differentiation (the recognition of different dimensions within, or perspectives on, a given stimulus) and integration (the recognition of trade-offs, syntheses, and higher order concepts relating the differentiated units). In the current study, 1 positive (e.g., professional achievement or marriage) and 1 negative (e.g., loss of employment or death of close relative) significant life event were identified in the biographies of 30 famous people. Random samples of correspondence from periods 1–2 yrs before, during, and 1–2 yrs after each selected event were scored for integrative complexity. In contrast with previous archival research, in which major stressors (war, increasing international tension, or approaching death) were correlated with reductions in complexity for many (although not all) Ss, the current data showed a substantial increase in the complexity of letters written around the time of negative life events. This was followed by a decrease to around-baseline levels in letters written during the postevent period. Differences were found between the patterns of male and female Ss. There were no significant changes associated with positive life events. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Phyto-oestrogens: where are we now?

Phyto-oestrogens have emerged from their esoteric role in animal husbandry following the hypothesis that the human Western diet is relatively deficient in these substances compared with societies where large amounts of plant foods and legumes are eaten. Evidence is beginning to accrue that they may begin to offer protection against a wide range of human conditions, including breast, bowel, prostate and other cancers, cardiovascular disease, brain function, alcohol abuse, osteoporosis and menopausal symptoms. Of the two main classes of these weak oestrogens, the isoflavones are under intensive investigation due to their high levels in soyabean. Like the 'anti-oestrogen' Tamoxifen, these seem to have oestrogenic effects in human subjects in the cardiovascular system and bone. Although previously only available from food, isoflavones are now being marketed in health-food supplements or drinks, and tablets may soon be available over the counter as 'natural' hormone-replacement therapy. In cancer, anti-oestrogenic effects are thought to be important, although genistein especially has been shown to induce wide-ranging anti-cancer effects in cell lines independent of any hormone-related influence. There are few indications of harmful effects at present, although possible proliferative effects have been reported. In infants, the effects of high levels in soya milk formulas are uncertain. The second group, lignans, have been less investigated despite their known antioestrogenic effects and more widespread occurrence in foods. Investigation of the possible benefits of phyto-oestrogens is hampered by lack of analytical standards and, hence, inadequate methods for the measurement of low levels in most foods. This problem may prove to be a major dilemma for regulatory authorities, clinicians and others wishing to advise the general public on whether these compounds really do have the health benefits attributed to them.     

New perspectives on autobiographical memory: The integration of narrative processing and autobiographical reasoning.

Researchers from diverse psychological subdisciplines have increasingly turned their attention to the storied aspect of human thought. Narrative processing and autobiographical reasoning are 2 forms of this conscious thought. Narrative processing is the tendency to create thought units that use vivid imagery, sequential plots, characters, and salient goals. Autobiographical reasoning consists of interpreting and evaluating remembered experiences. Both forms of thought are discussed in D. P. McAdams's (see record 2001-06545-002) personality theory and D. B. Pillemer's (see record 2001-06545-003) cognitive research. S. Bluck and T. Habermas (see record 2001-06545-004) highlight developmental aspects of narrative processing and autobiographical reasoning, particularly in adolescent identity formation. U. M. Staudinger (see record 2001-06545-005) illustrates how autobiographical reasoning about memories and life stories serves as a springboard for wisdom at different stages of the life cycle. Implications for integrating subdisciplines of psychology are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Time-domain BIE analysis of large three-dimensional electromagneticscattering problems

A time-domain boundary integral equation (BIE) solution of the magnetic field integral equation (MFIE) for large electromagnetic scattering problems is presented. It employs isoparametric curvilinear quadratic elements to model fields, geometry, and time dependence, eliminating staircasing problems. The approach is implicit, which seems to provide both stability and permits arbitrary local mesh refinement to model geometrically difficult regions without the significant cost penalty explicit methods suffer. Error dependence on discretization is investigated; accurate results are obtained with as few as five nodes per wavelength. The performance both on large scatterers and on low-radar cross section (RCS) scatterers is demonstrated, including the six wavelength “NASA almond,” two spheres, a thirteen wavelength missile, and a “high-Q” cavity     

An accurate method for the calculation of singular integralsarising in time-domain integral equation analysis of electromagneticscattering

An accurate method for the evaluation of the Cauchy principal value integrals arising in time-domain electromagnetic wave scattering is presented. This is applied to a boundary integral equation (BIE) method employing quadratic curvilinear surface elements where such singularities do not vanish (as they generally do when simpler but less accurate discretizations are employed). The technique involves weakening the singularity in the original kernel to a degree where conventional integration methods may be employed and transforming the strong singularity to a line integral in a form which allows cancellation of its singular components. The effectiveness of the method is demonstrated by scattering calculations on a variety of targets and the computational cost of the approach is trivial     

Getting a life: The emergence of the life story in adolescence.

In the life story, autobiographical remembering and self-understanding are combined to create a coherent account of one's past. A gap is demonstrated between developmental research on the story-organization of autobiographical remembering of events in childhood and of life narratives in adulthood. This gap is bridged by substantiating D. P. McAdams's (1985) claim that the life story develops in adolescence. Two manifestations of the life story, life narratives and autobiographical reasoning, are delineated in terms of 4 types of global coherence (temporal, biographical, causal, and thematic). A review of research shows that the cognitive tools necessary for constructing global coherence in a life story and the social-motivational demands to construct a life story develop during adolescence. The authors delineate the implications of the life story framework for other research areas such as coping, attachment, psychotherapeutic process, and the organization of autobiographical memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)