Desired concentration-dependent ion exchange for micro-optic lenses

The required concentration-dependent diffusion coefficients for both ideal one-dimensional and ideal radial gradient-index profiles are determined. The modified quasi-chemical diffusion model is used to relate the diffusion coefficient to optimum glass composition. Adding aluminum to sodium silicate glasses facilitates the approach to the desired concentration dependence of the diffusion coefficient for silver-sodium ion exchange. A parabolic one-dimensional index profile is fabricated in one of the glasses. It deviates from ideal values by less than 2%.     

Robotic control in knee joint replacement surgery

A brief history of robotic systems in knee arthroplasty is provided. The place of autonomous robots is then discussed and compared to more recent 'hands-on' robotic systems that can be more cost effective. The case is made for robotic systems to have a clear justification, with improved benefits compared to those from cheaper navigation systems. A number of more recent, smaller, robot systems for knee arthroplasty are also described. A specific example is given of an active constraint medical robot, the ACROBOT system, used in a prospective randomized controlled trial of unicondylar robotic knee arthroplasty in which the robot was compared to conventional surgery. The results of the trial are presented together with a discussion of the need for measures of accuracy to be introduced so that the efficacy of the robotic surgery can be immediately identified, rather than have to wait for a number of years before long-term clinical improvements can be demonstrated.     

Quantification of heart fatty acid binding protein as a biomarker for drug-induced cardiac and musculoskeletal necroses

Heart fatty acid binding protein (Fabp3) is a cytosolic protein expressed primarily in heart, and to a lesser extent in skeletal muscle, brain, and kidney. During myocardial injury, the Fabp3 level in serum is elevated rapidly, making it an ideal early marker for myocardial infarction. In this study, an MS‐based selected reaction monitoring method (LC‐SRM) was developed for quantifying Fabp3 in rat serum. Fabp3 was enriched first through an immobilized antibody, and the protein was digested on beads directly. A marker peptide of Fabp3 was quantified using LC‐SRM with a stable isotope‐labeled peptide standard. For six quality control samples with Fabp3 ranging from 0.256 to 25 ng, the average recovery following the procedure was about 73%, and the precision (%CV) between replicates was less than 7%. The Fabp3 concentrations in rat serum peaked 1 h after isoproterenol treatment, and returned to baseline levels 24 h after the dose. Elevated Fabp3 levels were also detected in rats administered with a PPAR α/δ agonist, which has shown to cause skeletal muscle necrosis. Fabp3 can be used as a biomarker for both cardiac and skeletal necroses. The cross‐validation of the LC‐SRM method with an existing ELISA method is described.     

The influence of music on mood and performance while driving

Mood can influence our everyday behaviour and people often seek to reinforce, or to alter their mood, for example by turning on music. Music listening while driving is a popular activity. However, little is known about the impact of music listening while driving on physiological state and driving performance. In the present experiment, it was investigated whether individually selected music can induce mood and maintain moods during a simulated drive. In addition, effects of positive, negative, and no music on driving behaviour and physiological measures were assessed for normal and high cognitive demanding rides. Subjective mood ratings indicated that music successfully maintained mood while driving. Narrow lane width drives increased task demand as shown in effort ratings and increased swerving. Furthermore, respiration rate was lower during music listening compared to rides without music, while no effects of music were found on heart rate. Overall, the current study demonstrates that music listening in car influences the experienced mood while driving, which in turn can impact driving behaviour. PRACTITIONERS SUMMARY: Even though it is a popular activity, little is known about the impact of music while driving on physiological state and performance. We examined whether music can induce moods during high and low simulated drives. The current study demonstrates that in car music listening influences mood which in turn can impact driving behaviour. The current study shows that listening to music can positively impact mood while driving, which can be used to affect state and safe behaviour. Additionally, driving performance in high demand situations is not negatively affected by music.     

Frequency-following reference oscillator for a two-phase lock-in amplifier

The circuit for a frequency-following oscillator is described for use in obtaining a commensurate reference for a two-phase lock-in amplifier. This device is useful in tracking signals which drift slowly in frequency and which are apt to be either intermittent or momentarily small in amplitude, as in the Brownian motion of a mechanical oscillator. Digital hysteresis is used to reduce the number of tracking corrections made when the signal and the reference oscillator are close in frequency and to increase the number of corrections when they are not.     

Calibration of AFM cantilever spring constants

In this paper we present two simple, reliable and readily applicable methods for calibrating cantilevers and measuring the thickness of thin gold films. The spring constant calibration requires knowledge of the Young's modulus, density of the cantilever and resonant frequency. The thickness of thin gold layers was determined by measuring changes in the resonant frequency and Q-factor of beam shaped AFM cantilevers before and after coating.The techniques for measuring the spring constant and thin film thickness provide accuracy on the order of 10-15%.     

Maternal diet and brain fatty acids in young rats

In order to determine to what extent maternal diet influenced the brain lipids of young rats, female rats were maintained on diets differing in fatty acid composition. Fatty acid determinations on the total brain lipids of the young from these dams indicated that the maternal dietary lipids influence the polyunsaturated fatty acid composition of these animals. A maternal diet with a high linoleic-linolenic acid ratio (corn oil) resulted in lower levels of 22∶6ω3 and higher levels of 22∶5ω6 than one with a low linoleic-linolenic acid ratio (grain). Transfer of young rats at birth to a foster mother, which was fed a diet differing from that of the natural dam, resulted in brain polyunsaturated fatty acid patterns at weaning similar to those of the natural young, and suckling, of the foster mother, thus indicating that the maternal diet in the immediate postnatal period can modify the brain lipids of young rats prior to weaning. The brain lipids of young rats from dams which were fed corn oil exhibited a marked tendency to incorporate 22∶6ω3 in the immediate postnatal period in spite of a relatively high linoleic-linolenic acid ratio in the milk.     

Stir bar sorptive extraction and trace analysis of selected endocrine disruptors in water, biosolids and sludge samples by thermal desorption with gas chromatography-mass spectrometry

Stir bar sorptive extraction (SBSE) in combination with thermal desorption coupled to gas chromatography-mass spectrometry (GC-MS) was successfully applied to analyze a range of endocrine disrupting compounds (EDCs) in wastewater, solids and sludge. The targeted EDCs include sex steroid hormones, phthalates, alkylphenols and tamoxifen. Recovery for the EDCs using this analytical technique ranged from 44% to 128%. Limit of detection (LOD) of the compounds was 2.0 ng/L for water samples and 0.02 ng/g for solid samples, whereas the limit of quantitation (LOQ) was 5.0 ng/L for water samples and 0.06 ng/g for solid samples. When this analytical technique was applied to measure EDC concentration in a biological nutrient removal (BNR) wastewater treatment plant located in South East Queensland, Australia, the results showed that there were high amounts of phthalates, alkylphenols and female hormones present in the raw influent wastewater and solids. These concentrations were dramatically reduced after passing through the various treatment zones of the bioreactor (anaerobic, aerobic and anoxic).     

Changes in blood lead of a recreational shooter

We have measured the concentration and isotopic composition of lead in blood over a 15-month period for a subject who undertook recreational shooting in outdoor and indoor firing ranges on an irregular basis. We have also measured the isotopic composition in cast lead, Cu-jacketed and Teflon-coated bullets, propellant and primer from which he assembled the cartridges. Blood lead concentration increased from 3.2 to 6.7 microg/dl with use of dominantly cast lead bullets in the outdoor range. In two intervals when no firing was undertaken for 3-4 months, the blood lead concentrations either decreased towards a baseline value in the case where only Cu-jacketed bullets were fired or remained elevated when dominantly cast lead bullets were fired. The propellants contained <2 ppm Pb and contribute negligibly to blood lead. The isotopic composition of the primer used for all bullets was consistent with a source from the US. The bullets were of different materials and made in Australia and the US, with lead from sources of different geological age and hence different isotopic signatures. Variations in blood lead concentration and isotopic composition appear most strongly influenced by the bullets. Although more expensive, the use of Cu-jacketed bullets, non-lead primers and well-ventilated indoor firing ranges would lessen the health impacts of recreational shooting.     

Reduced insulin-like growth factor-I after acute feed restriction in lactating dairy cows is independent of changes in growth hormone receptor 1A mRNA

Growth hormone receptor (GHR) and insulin-like growth factor-I (IGF-I) mRNA decrease in the liver of dairy cows at parturition. Epinephrine is released and feed intake is decreased at the same time. The objective of this study was to determine whether feed restriction and (or) administration of epinephrine could recapitulate the changes in the hepatic GHR 1A and IGF-I mRNA that occur at parturition. Eight lactating cows were randomly assigned to one of two rations (ad libitum or restricted). The cows assigned to the restricted ration were fed 75, 60, 60, and 25% of feed consumed by the ad libitum cows on successive days to mimic the changes in feed intake around parturition. Liver samples were collected by needle biopsy before and after feed restriction. Cows received either 0.02 mg/kg of epinephrine or saline approximately 24 h before the second liver biopsy so that a 2 x 2 factorial arrangement of treatments was created. Feed restriction increased plasma nonesterified fatty acids and liver triglyceride percentages and decreased plasma IGF-I concentrations. The decrease in plasma IGF-I after feed restriction was associated with a decrease in IGF-I mRNA in feed-restricted cows. The amount of GHR 1A mRNA did not change after feed restriction. Epinephrine treatment did not affect the amount of GHR 1A or IGF-I mRNA. We conclude that the decrease in feed intake at parturition may be partially responsible for the decrease in IGF-I but may not cause the decrease in GHR 1A.