J-substitution algorithm in magnetic resonance electrical impedance tomography (MREIT): phantom experiments for static resistivity images

Recently, a new static resistivity image reconstruction algorithm is proposed utilizing internal current density data obtained by magnetic resonance current density imaging technique. This new imaging method is called magnetic resonance electrical impedance tomography (MREIT). The derivation and performance of J-substitution algorithm in MREIT have been reported as a new accurate and high-resolution static impedance imaging technique via computer simulation methods. In this paper, we present experimental procedures, denoising techniques, and image reconstructions using a 0.3-tesla (T) experimental MREIT system and saline phantoms. MREIT using J-substitution algorithm effectively utilizes the internal current density information resolving the problem inherent in a conventional EIT, that is, the low sensitivity of boundary measurements to any changes of internal tissue resistivity values. Resistivity images of saline phantoms show an accuracy of 6.8%-47.2% and spatial resolution of 64 x 64. Both of them can be significantly improved by using an MRI system with a better signal-to-noise ratio.     

Prandtl and capillary effects on heat transfer performance within laminar liquid–gas slug flows

This paper investigates a two-phase non-boiling slug flow regime for the purposes of enhancing heat transfer in microchannel heat sinks or compact heat exchangers. The primary focus is upon understanding the mechanisms leading to enhanced heat transfer and the effect of using different Prandtl number fluids, leading to variations in Capillary number. Experimental work was conducted using Infrared thermography and results are presented in the form of Graetz solution, spanning both the thermal entrance and fully developed flow regions. Nusselt numbers enhancements were observed throughout when data was reduced to account for void fraction. However, the gaseous void was also noted to demonstrate an artificial increase with greater thicknesses of the liquid film, due to higher Capillary numbers. Up to 600% enhancement in heat transfer rates were observed over conventional Poiseuille flow. This was verified through Nusselt number measurements over inverse Graetz number ranges from 10^?4 to 1 and slug length to channel diameter ratios from 0.88 to 32. Varying Prandtl and Capillary numbers caused notable effects in the transition region between entrance and fully developed flows. Significant Nu oscillations were observed for low Pr fluids due to internal circulation within the slug. However, these oscillations are observed to be damped out when higher Prandtl number fluids are employed. The thickness of the liquid film surrounding the gas bubbles is shown to have a significant influence on heat transfer performance. Overall, this study provides a greater understanding of the mechanisms leading to significant enhancements in heat exchange devices employing two-phase gas–liquid flows without boiling.     

A Neuromorphic VLSI Model of Bat Interaural Level Difference Processing for Azimuthal Echolocation

Bats use the unusual sensory modality of echolocation to fly in complete darkness with speed and agility through complex three-dimensional environments. Their small head size and the use of high-frequency sound make interaural level differences (ILDs) their primary cue for azimuthal echolocation. In this paper, we present a neuromorphic VLSI-based system that emulates the ILD processing in the bat brainstem and midbrain. By selecting simple neural units, we propose a circuit model that is mathematically tractable and captures the essential elements of bat ILD computation. The chip includes a three-layer network of spiking neurons with 32 neurons on each layer, and the address-event representation for external interface. Emphasizing the neural spike timing and population behavior, we hope this study will contribute to the bat research community in particular as well as neuroscience in general by providing a real-time, fine-grained, neuromorphic bat echolocation simulator that will be used to address system-level performance of low-level neural algorithms. By developing functional models of the bat echolocation system, we hope to emulate the efficient implementation demonstrated by nature     

The effect of regular exercise on women receiving danazol for treatment of endometriosis

OBJECTIVE: To determine the effects of regular exercise on women receiving danazol for the treatment of endometriosis. METHODS: Thirty-nine patients were randomized to a danazol-only or a danazol/exercise regimen in a prospective clinical trial carried out at tertiary care institutions. Patients in the danazol/exercise group were instructed to exercise four times per week, for 40 min per session, at an intensity of 20 metabolic units. Side effect profiles, pelvic symptoms, aerobic fitness, strength and hormone levels were compared for all subjects. The number of side effects of danazol was analyzed by the method of generalized estimating equations. RESULTS: The number of side effects reported during a 4-week period was 1.09-2.17 times greater for the danazol-only than for the danazol/exercise group. All patients had improvement of symptoms during treatment. The danazol/exercise group had significantly lower testosterone levels during treatment. The time to recurrence of endometriosis was not different between groups. CONCLUSIONS: Exercise during danazol therapy reduces the number of androgenic side effects. Relief of pain and time to recurrence are unaffected.     

Development and validation of minicourses in the telecommunication industry.

Beginning in the early 1970s, American Telephone and Telegraph (AT&T) and the associated Bell companies have used minicourses for selecting personnel in a variety of jobs involving new technologies. The minicourse approach uses material representative of training content to assess the candidate's ability to acquire knowledge relevant to full-scale training and the job. A major advantage of the minicourse approach is the ability to implement a selection procedure concurrent with the introduction of a new training program. Although minicourses are initially validated using a content-oriented strategy, the AT&T model has included criterion-related validation where possible. The experience of AT&T with seven minicourses is discussed, and validities for training criteria and job performance are reported. Minicourses are a specific example of the general class of predictors known as trainability tests. The results of a meta-analysis indicate that validities for trainability tests are comparable with validities found for ability tests and work sample tests by Hunter and Hunter (1984). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Relation between power and endurance for treadmill running of short duration

An exercise test was devised to investigate the relationship between power and endurance for treadmill running. The subjects were 19 males aged 21-25 yr (11 distance runners and 4 sprinters of provincial grade, and 4 non-competitive runners). Each subject ran to exhaustion on a treadmill at 15 km hr-1 at five different inclinations (31%-9%), giving maximum performance times in the range 10 s to 3 min. An iterative least-squares procedure was used to fit the following exponential model to each subject's data: It = I infinity + (I0-I infinity) exp (-t/tau), where It, I0 and I infinity are inclinations at time t = t, t = 0 and t----infinity, and tau is a time constant. The fit was excellent (r2 = 0.96-1.00). I0 and I infinity are interpreted as measures of maximum anaerobic (instantaneous) and maximum aerobic (continuous) power respectively. Inclinations corresponding to performance times of 10-180 s (I10-I180) were calculated from these parameters. Test-retest reliability was highest for I0-I30 (intraclass r = 0.97-0.94), lower for I60-I infinity (r = 0.89-0.84), and lowest for tau (r = 0.78). Good correlations were observed between I0-I30 and peak power in a 30 s all-out test on a cycle ergometer (r = 0.73-0.81), and between I180, I infinity and maximum oxygen consumption (r = 0.87, 0.81). The test may be useful for ranking or monitoring running performance for events of up to 1 min duration.