A circuit approach to field computation

Many design objectives can be expressed more directly in terms of circuit parameters, such as capacitance and inductance, than in terms of the field vectors E and B. A simple, although radical, change is suggested to provide a closer link between the field and circuit views. The electric potential φ and magnetic vector A are defined, in energy terms, as the primary field quantities, and they are visualized as measures of the capacitance and inductance, respectively. E and B become auxiliary symbols denoting derivatives, so that the customary roles of the potentials and field vectors are reversed. Some of the practical advantages of the change are examined and are illustrated by example     

ART-EMAP: A neural network architecture for object recognition byevidence accumulation

A new neural network architecture is introduced for the recognition of pattern classes after supervised and unsupervised learning. Applications include spatio-temporal image understanding and prediction and 3D object recognition from a series of ambiguous 2D views. The architecture, called ART-EMAP, achieves a synthesis of adaptive resonance theory (ART) and spatial and temporal evidence integration for dynamic predictive mapping (EMAP). ART-EMAP extends the capabilities of fuzzy ARTMAP in four incremental stages. Stage 1 introduces distributed pattern representation at a view category field. Stage 2 adds a decision criterion to the mapping between view and object categories, delaying identification of ambiguous objects when faced with a low confidence prediction. Stage 3 augments the system with a field where evidence accumulates in medium-term memory. Stage 4 adds an unsupervised learning process to fine-tune performance after the limited initial period of supervised network training. Each ART-EMAP stage is illustrated with a benchmark simulation example, using both noisy and noise-free data.     

Diagnosis and treatment planning for implant dentistry

Dental implants are well-established in dentistry and allow the restorative dentist to offer patients the best that dentistry has to offer. Through examination, radiographs, and study models, the restorative dentist and implant surgeon can develop a treatment plan. Comprehensive diagnosis and treatment planning involve much more than a clinical exam--they require an investigation involving past, present and future dental therapy.     

Postischemic hyperglycemia worsens neurologic outcome after spinal cord ischemia

PURPOSE: The neurologic effect of induced hyperglycemia in the postischemic period was investigated with a rat aortic occlusion model. METHODS: Sprague-Dawley rats weighing 200 to 350 gm were anesthetized, intubated, and ventilated with 1% to 1.5% halothane. Temperature was continuously monitored and maintained at 37 degrees +/- 0.5 degrees C. The chest was opened, the thymus excised, and the aortic arch exposed. Snares were placed around the aorta distal to the left subclavian artery and the right and left subclavian arteries. The three vessels thus isolated were occluded for 8 minutes. With snare release and withdrawal, the rats received an intraperitoneal injection of 5% dextrose in water (2 gm/kg) or an equivalent volume of 0.9% saline solution. In a second group of rats the administration of glucose or saline solution was delayed until 30 minutes after snare release. Blood samples for blood glucose determination were obtained before operation, before occlusion, immediately after occlusion, and 15, 30, 45, 60, and 240 minutes after occlusion. A neurologic deficit score was assigned at 1, 4, 18, and 24 hours after occlusion to quantify hindlimb neurologic deficit based on 15-point scale (0 = normal, 15 = severe deficit). Sham-operated rats received the same operation and injection, but the snares were only manipulated and not made occlusive. RESULTS: The rats that were administered glucose immediately after snare release showed a statistically significant exacerbation of lower extremity neurologic deficit at 24 hours after occlusion (p < or = 0.05, Mann-Whitney U test). The sham-operated rats were normal (0 score) at 24 hours. Significant elevation of blood glucose (321 +/- 33 mg/dl) was seen in the glucose-injected rats at 15 minutes and continued for up to 4 hours after occlusion (p = 0.040 and 0.014, respectively; Student's t test). CONCLUSION: Postischemic hyperglycemia immediately after a standard spinal cord ischemic stress worsens neurologic outcome.     

New energy transfer dyes for DNA sequencing

We have synthesized a set of four energy transfer dyes and demonstrated their use in automated DNA sequencing. The donor dyes are the 5- or 6-carboxy isomers of 4'-aminomethylfluorescein and the acceptor dyes are a novel set of four 4,7-dichloro-substituted rhodamine dyes which have narrower emission spectra than the standard, unsubstituted rhodamines. A rigid amino acid linker, 4-aminomethylbenzoic acid, was used to separate the dyes. The brightness of each dye in an automated sequencing instrument equipped with a dual line argon ion laser (488 and 514 nm excitation) was 2-2.5 times greater than the standard dye-primers with a 2 times reduction in multicomponent noise. The overall improvement in signal-to-noise was 4- to 5-fold. The utility of the new dye set was demonstrated by sequencing of a BAC DNA with an 80 kb insert. Measurement of the extinction coefficients and the relative quantum yields of the dichlororhodamine components of the energy transfer dyes showed their values were reduced by 20-25% compared with the dichlororhodamine dyes alone.     

Transient conduction in a slab with chemical reaction

The heat-balance integral technique is used to analyse a one-dimensional transient conduction process. Heat is transferred by convection to the surface of a slab and when the surface temperature reaches a certain value, an endothermic reaction is triggered which propagates as an isothermal front in the same direction as the conduction front. Two possible routes to the fully developed heat transfer condition are treated in a way which allows the approximate temperature distribution in the slab to be predicted as a function of the main process variables.     

Effects of corticotropin-releasing factor on brain serotonergic activity

The serotonergic dorsal raphe nucleus is innervated by corticotropin-releasing factor (CRF) and expresses CRF receptors, suggesting that endogenous CRF impacts on this system. The present study characterized interactions between CRF and the dorsal raphe serotonin (5-HT) system. The effects of intracerebroventricularly (i.c.v.) administered CRF on microdialysate concentrations of 5-HT in the lateral striatum of freely moving rats were determined. CRF had biphasic effects, with 0.1 and 0.3 microgram decreasing, and 3.0 micrograms increasing 5-HT dialysate concentrations. i.c.v. administration of CRF inhibited neuronal activity of the majority of dorsal raphe neurons at both low (0.3 microgram) and high (3 micrograms) doses. Likewise, intraraphe administration of CRF (0.3 and 1.0 ng) had predominantly inhibitory effects on discharge rate. Together, these results suggest that CRF is positioned to regulate the function of the dorsal raphe serotonergic system via actions within the cell body region. This regulation may play a role in stress-related psychiatric disorders in which 5-HT has been implicated.