A network analyzer-based tissue characterization system

A novel ultrasound tissue characterization system is described which utilizes a network analyzer, S-parameter test set, 180° hybrid junction, and a mock transducer circuit to exploit the wide-band potential of a commercial piezoelectric polymer transducer. The relatively short round-trip pulselength achieved using the system (70 ns in water) is compared to that obtained using a high-frequency pulser/receiver and the same transducer (130 ns in water). Finally, the in vitro acoustic response of a section of neonate porcine carotid artery obtained using the network analyzer-based system is reported, along with histologic results for the same vessel     

Attentional task aptitude and performance anxiety.

Anxious responding (trait, state, and test anxiety) has a negative impact on overt performance. Researchers have used a unidimensional method of assessing anxiety and performance, although a more informative approach would involve a comprehensive assessment battery and multiple performance tasks. Incorporating this strategy, the authors measured the impact of anxiety on 4 attentional processing tasks. Results revealed that "types" of anxiety symptoms were differentially related to attentional task performance; test anxiety accounted for the most variance in predicting performance on the Wechsler Adult Intelligence Scale-Third Edition (D. Wechsler, 1997) letter-number sequencing and digit-span subtests, trait anxiety and fear of negative evaluation were more significant in predicting Stroop performance, and math anxiety accounted for the largest variance toward understanding Paced Auditory Serial Addition Task (C. W. Lejuez, C. W. Kahler, & R. A. Brown, 2003) scores. Theoretical and clinical implications are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The reaction of liquid metals to form intermetallics

The formation of intermetallic compounds of high melting point, by reaction between liquid metals at low temperatures, was studied for a number of binary systems, in particular Al-Sb, Mg-Sb, Mg-Bi and Na-Bi.Two regimes of behaviour on mixing were found:

Effects of low-voltage electrical stimulation during exsanguination on meat quality and display colour stability

Five steers from each of four slaughter groups were randomly assigned to a low-voltage electrical stimulation (LVES) treatment during exsanguination (within 5 min after stunning) and five served as controls (C). LVES consisted of 50V of 60 Hz alternating current (1 s on and 1 s off for 2 min).

At 28 h, LVES longissimus (LM) was lighter in colour, softer, coarser in texture and tended to have lower marbling estimates than C. LVES LM steaks were lighter red at 0 and 1 days, but more discoloured at 5 days, of display than C steaks. Both the deep (DSM) and superficial (SSM) portions of LVES semimembranosus (SM) steaks were lighter red at 0 and 1 days of display than C steaks. Water-holding capacity for LVES LM and DSM steaks was lower than for C steaks. A trained sensory panel found LVES LM steaks to be less juicy and less tender than C steaks. Also, LVES LM steaks had greater cooking losses than C steaks in two of the four slaughter groups. We conclude that LVES during exsanguination, coupled with relatively slow initial chilling, may be detrimental to muscle quality.     

Incorporating fuzzy membership functions into the perceptron algorithm

The perceptron algorithm, one of the class of gradient descent techniques, has been widely used in pattern recognition to determine linear decision boundaries. While this algorithm is guaranteed to converge to a separating hyperplane if the data are linearly separable, it exhibits erratic behavior if the data are not linearly separable. Fuzzy set theory is introduced into the perceptron algorithm to produce a ``fuzzy algorithm' which ameliorates the convergence problem in the nonseparable case. It is shown that the fuzzy perceptron, like its crisp counterpart, converges in the separable case. A method of generating membership functions is developed, and experimental results comparing the crisp to the fuzzy perceptron are presented.     

Polystyrenes in channels

Polystyrenes (PS) with various stereosequences have been modeled in narrow cylindrical channels corresponding to those found in polymer-inclusion compounds (ICs), such as those formed with host cyclodextrins (CDs), where the polymers reside as guests. Isotactic (i) PS is found to fit in channels with narrower diameters (D) than syndiotactic (s) PS, when both adopt conformations permitted by the Yoon, Sundararajan, Flory RIS conformational model of PSs, while atactic (a) PS can be included in channels with D intermediate to those for i- and s-PS. In ICs formed with host γ-CD and guest a-PS homopolymer and guest poly(?-caprolactone) (PCL)-b-a-PS diblock copolymer it was observed that the a-PS homopolymer and the a-PS copolymer blocks were and were not included, respectively. Thus, it appears that a-PS is barely able to be threaded by γ-CD, whose internal diameter is ∼8 Å. Because the channel conformers found for i- and s-PS have smaller and larger diameters, respectively, than those found for a-PS, we would expect i-PS to be complexed by γ-CD, while s-PS might not. As a consequence IC formation with γ-CD may provide a means to physically separate the stereoregular forms of polystyrene. In addition, only the mrm and rmr PS stereoisomers show channel conformations with significant probabilities, so we suggest that in situ polymerization of styrene monomer in the narrow channels of its IC formed with γ-CD might produce a new stereoregular form of PS with regularly alternating m and r diads.     

The involvement of 1,6-diphenyl-1,3,5-hexatriene and 1,8-diphenyl-1,3,5,7-octatetraene in the radical polymerization of methyl methacrylate

Summary The , -diphenyl derivatives of 1,3,5-hexatriene and 1,3,5,7-octatetraene strongly retard the radical polymerization of methyl methacrylate (MMA); the effects are greater when initiation is achieved with benzoyl peroxide than when azobisisobutyronitrile is used. The tetraene and the triene are respectively 575 and not less than 240 times as effective as MMA in capturing the benzoyloxy radical at 60°C.     

Effect of polyaluminium chloride on phosphorus removal in constructed wetlands treated with swine wastewater

Total phosphorus (TP) removal in aged constructed wetlands poses a challenge, especially when treated with swine wastewater with high concentrations of phosphorus (P). Our earlier studies with anaerobic lagoon swine wastewater treatment in constructed wetlands showed a decline in P removal (45-22%) with increased years of operation. These particular wetlands have been treated with swine wastewater every year since the first application in 1997. Preliminary lab-scale studies were conducted to evaluate the efficiency of polyaluminium chloride (PAC) in the removal of phosphate-P (PO4-P) from swine wastewater. The experimental objective was to increase the phosphorus treatment efficiency in constructed wetland by adding PAC as a precipitating agent. PAC was added by continuous injection to each wetland system at a rate of 3 L day(-1) (1:5 dilution of concentrated PAC). Swine wastewater was added from an anaerobic lagoon to four constructed wetland cells (11m wide x 40m long) at TP loads of 5.4-6.1 kg ha(-1) day(-1) in two experimental periods, September to November of 2008 and 2009. Treatment efficiency of two wetland systems: marsh-pond-marsh (M-P-M) and continuous marsh (CM) was compared. The wetlands were planted with cattails (Typha latifolia L.) and bulrushes (Scirpus americanus). In 2008, PAC treatment showed an increase of 27.5 and 40.8% of TP removal over control in M-P-M and CM respectively. Similar trend was also observed in the following year. PAC as a flocculant and precipitating agent showed potential to enhance TP removal in constructed wetlands treated with swine wastewater.     

Water balance modelling of alternate water sources at the household scale

Alternate water sources are being implemented in urban areas to augment scheme water supplied by a water utility to homes. These sources include residential wells, rainwater tanks and greywater systems. Greater water efficiency can be achieved when these systems are designed to match a water source to a given demand based on both water quantity and quality parameters. In this way the use of an alternate water source can be maximised and the use of the high quality scheme water minimised. This paper examines the use of multiple alternate water sources sequentially to supply the same demand point potentially optimising the use of all available water sources. It also allows correct sizing of such water systems and their components to reduce scheme water demand. A decision support tool based on water balance modelling was developed that considers such water options at the household scale. Application of this tool to eight scenarios for both large and small house lots shows that using alternate water sources individually can result in significant scheme water savings. However by integrating these sources additional scheme water saving can be made.     

Determination of the average orientation of DNA in the octopus sperm Eledone cirrhossa through polarized light scattering

The coupled-dipole approximation has been used to model polarized light-scattering data obtained from the sperm of the octopus Eledone cirrhosa. Mueller scattering-matrix elements (which describe how a sample alters the intensity and degree of polarization of scattered light) were measured as a function of angle. The sample was modeled as a helical fiber believed to correspond to a DNA protein complex. It was necessary to propose an inherent anisotropy in the polarizability of the fiber in order to fit the data. The direction of the principle axes of the polarizability were determined by comparing the model with experimental data. The results suggest that the 2-nm DNA fibers are perpendicular to the thick fiber that defines the helical geometry of the octopus sperm head.