60,814 research outputs found
The biological cost of consciousness
Some philosophers maintain that consciousness as subjective experience has no biological function. However, conscious brain events seem very different from unconscious ones. The cortex and thalamus support the reportable qualitative contents of consciousness. Subcortical structures like the cerebellum do not. Likewise, attended sensory stimuli are typically reportable as conscious, while memories of those stimuli are not so reportable until they are specifically recalled. 

Reports of conscious experiences in normal humans always involve subjectivity and an implicit observing ego. Unconscious brain events are not reportable, even under optimal conditions of report. While there are claimed exceptions to these points, they are rare or poorly validated. 

Normal consciousness also implies high availability (rapid conscious access) of the questions routinely asked of neurological patients in the Mental Status Examination, such as common sense features of personal identity, time, place, and social context. Along with “current concerns,” recent conscious contents, and the like, these contents correspond to high frequency items in working memory. While working memory contents are not immediately conscious, they can be rapidly re-called to consciousness. 

The anatomy and physiology of reportable conscious sensorimotor contents are ultraconserved over perhaps 200 million years of mammalian evolution. By comparison, full-fledged language is thought to arise some 100,000 years ago in homo sapiens, while writing, which enables accel-erated cultural development, dates between 2.5 and 6 millennia. Contrary to some claims, therefore, conscious waking precedes language by hundreds of millions of years. 

Like other major adaptations, conscious and unconscious brain events have distinctive biological pros and cons. These involve information processing efficiency, metabolic costs and benefits, and behavioral pros and cons. The well known momentary limited capacity of conscious contents is an example of an information processing cost, while the very large and energy-hungry corticothalamic system makes costly metabolic demands. 

After a century of scientific neglect, fundamental concepts like “conscious,” “unconscious,” “voluntary” and “non-voluntary” are still vitally important, because they refer to major biopsychological phenomena that otherwise are difficult to discuss. 

The reptating rope model: Viscometric functions for concentrated polymer solutions and melts in shear flow
The viscometric functions for shear flow as predicted by the inextensible reptating rope model have been analysed numerically and analytically. The results obtained are compared with the predictions of the CurtissāBird theory. It is shown that if the correlation length of the rope is small as compared to its contour length significant deviations from the CurtissāBird theory are obtained. Results are presented for: (a) the onset of shear flow, (b) steady state shear flow and (c) small amplitude oscillatory shear flow
Recollections of My Research in Developing the Heart-Lung Machine at Jefferson Medical College
A personal memoir written by Dr. Bernard J. Miller about his introduction to and interest in medical research as well as his experiences working on the heart-lung machine. He focuses specifically on his working relationship with John H. Gibbon, Jr., the development of a viable oxygenator and ventilator, and early testing of the machine on animal
Regularization modeling for large-eddy simulation of diffusion flames
We analyze the evolution of a diffusion flame in a turbulent mixing layer using large-eddy simulation. The large-eddy simulation includes Leray regularization of the convective transport and approximate inverse filtering to represent the chemical source terms. The Leray model is compared to the more conventional dynamic mixed model. The location of the flame-center is defined by the 'stoichiometric' interface. Geometrical properties such as its surface-area and wrinkling are characterized using an accurate numerical level-set quadrature method. This allows to quantify flame-properties as well as turbulence modulation effects due to coupling between combustion and turbulent transport. We determine the active flame-region that is responsible for the main part of the chemical conversion in the flame and compare direct and large-eddy simulation predictions
Bessel and Struve Related Integrals
Analytic expressions for integrals which arise in a theory of atomic
structure due to Schwinger and Englert are evaluated in terms of Bessel and
Struve functionsComment: 10 page
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