Low-power design for embedded processors

Minimization of power consumption in portable and battery powered embedded systems has become an important aspect of processor and system design. Opportunities for power optimization and tradeoffs emphasizing low power are available across the entire design hierarchy. A review of low-power techniques applied at many levels of the design hierarchy is presented, and an example of low-power processor architecture is described along with some of the design decisions made in implementation of the architecture     

Psychosocial outcomes of breast-conserving surgery versus mastectomy: A meta-analytic review.

Effective breast-conserving surgical techniques for early-stage disease were developed to improve breast cancer patients' quality of life. The literature comparing the psychosocial sequelae of these newer treatments with mastectomy is ambiguous and shows an unexpected lack of substantial benefits. To clarify these inconsistencies, meta-analytic methods were used to summarize the findings of 40 investigations. Mean weighted effect sizes were calculated for 6 psychosocial outcomes. Modest advantages for breast-conserving surgery were identified for psychological, marital-sexual, and social adjustment; body/self-image; and cancer-related fears and concerns. Method of assignment to treatment and timing of assessment were relevant for some outcomes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Quipazine and light have similar effects on c-fos induction in the rat suprachiasmatic nucleus

The effects of the serotonin agonist, quipazine, on the induction of c-fos in the suprachiasmatic nucleus of the rat was examined at different times of the 24 h cycle. Quipazine administered at night induced Fos production in a dose dependent manner (1, 3, 10, 30 mumol/kg) in the ventrolateral portion of the suprachiasmatic nucleus at ZT18. Administration of the highest dose at other times resulted in c-fos induction at ZT15 but not at other times of the day or subjective day examined (CT6 and ZT12). When compared to the effects of light pulses (2 lux/1 min), quipazine only caused c-fos induction at times when light caused induction. Our results support a role of serotonergic pathways in the transmission or modulation of photic information from the retina to the suprachiasmatic nucleus of the rat.     

The volume expansion accompanying the martensite transformation in iron-carbon alloys

A dilatometric investigation was conducted to determine the effect of carbon on the volume expansion accompanying the martensite transformation in iron-carbon alloys. It was found that the volume expansion at theM _s temperature varies from 2.0 pct at 0.19 wt pct carbon to 3.1 pet at 1.01 pct carbon, largely due to the effect of carbon on lowering the temperature at which the transformation occurs. Also of importance is the solid solution effect of carbon on altering the lattice parameters of both the austenite and martensite phases at theM_s.     

A methodology for crack tip mesh design

A methodology for crack tip mesh design is developed which consists of comparing the mesh geometric parameters against the accuracy of the finite element solution. By successive changes in the mesh parameters a near optimal mesh can be obtained. This was done here two-dimensional linear elastic single mode problems. The direct displacement extrapolation method for stress intensity factor estimation is used.     

Calcium-dependent afterhyperpolarization and learning in young and aging hippocampus

Hippocampally-dependent trace eyeblink conditioning has been shown to be affected by aging. Aging animals take more trials to acquire the association and are more likely to be unable to learn the task. Hippocampal neurons show decreased post-burst afterhyperpolarizations (AHPs) and less accomodation after conditioning, in a time-dependent fashion which may relate to the role of hippocampus in learning consolidation. CA1 neurons in aging rabbits show increased AHPs and more accomodation, i.e., they are less excitable, and larger calcium action potentials. These age-related changes may underlie the learning deficits in aging rabbits. The lipophylic calcium channel blocker nimodipine reduces the AHP, accomodation and calcium action potential at low concentrations in aging but not young CA1 neurons. Nimodipine also enhances learning rate in a variety of tasks, including eyeblink conditioning, in aging but not young animals and humans. Altered calcium handling by neurons of aging mammals is a striking change, is pharmacologically manipulable, and may be an important factor in altered learning and cognitive abilities in the aging.     

Modifying the Lambda Ratio to Functional Line Contacts

Lambda ratio, the lubricant film thickness divided by the composite roughness within an operating rolling element bearing, has been recognized for more than 25 years as an important contact parameter related to bearing performance, primarily fatigue life. This paper considers a simplified method of functional filtering within a bearing contact that provides a more appropriate composite roughness for a wider range of bearing sizes and loadings. The concept was tested with a series of regression models of standard and modified lambda ratios, including the uncoupled lambda parameters. The models were rated using three different statistical indices to assess how each model accounted for the variation present in a large collection of bearing test data.     

Rheo-small-angle neutron scattering at the National Institute of Standards and Technology Center for Neutron Research

We describe the design and operation of a modified commercial rheometer to simultaneously perform rheological measurements and structural studies by small angle neutron scattering (SANS). The apparatus uses a Couette geometry shear cell allowing two of the three scattering planes to be observed by performing experiments in either the radial or tangential geometries. The device enables small angle neutron scattering patterns to be obtained simultaneously with a wide variety of rheological measurements such as stress/strain flow curves, oscillatory deformations, and creep, recovery and relaxation tests, from -20?°C to 150?°C, for samples with viscosities varying by several orders of magnitude. We give a brief report of recent experiments performed on a dispersion of acicular nanoparticles and biopolymer network under stress demonstrating the utility of such measurements. This device has been developed at the National Institute of Standards and Technology's Center for Neutron Research (NCNR) and made available to the complex fluids community as part of the standard sample environment equipment.