Magnetization transfer with echo planar imaging

The aim of magnetization transfer is to saturate the protons of the macromolecule pool with a radiofrequency (RF) pulse leading to differences in free water pool signal. Magnetization transfer (MT) contrast is difficult to achieve with the echo planar imaging (EPI) technique, although its short acquisition time would be most beneficial. Indeed, the RF saturation pulses can only be applied once before sampling the whole k-space in a single-short sequence. A possible solution to improve the sensitivity of EPI to magnetization transfer consists in applying a train of several saturation RF pulses before image acquisition. The different parameters of a RF pulse train and their influence on the MT rate have been tested to optimize an EPI clinical sequence. Our experimental procedure makes it possible to obtain a MT map in about 1 second. The technique is evaluated by multiple sclerosis lesion characterization. Supported by grants from the French research ministry and Siemens medical France.     

The effect of colostrum storage conditions on dairy heifer calf serum immunoglobulin G concentration and preweaning health and growth rate

The objective of the present study was to compare serum IgG concentration, weight gain, and health characteristics in Irish spring-born dairy calves fed colostrum stored using a range of conditions. Immediately after birth, 75 dairy heifer calves were assigned to 1 of 5 experimental colostrum treatments: (1) fresh pasteurized colostrum, fed immediately after pasteurization; (2) fresh colostrum, fed immediately after collection but not pasteurized; (3) colostrum stored unpasteurized at 4°C in a temperature-controlled unit for 2 d before being fed to calves; (4) colostrum stored unpasteurized at 13°C in a temperature-controlled unit for 2 d before being fed to calves; and (5) colostrum stored unpasteurized at 22°C in a temperature-controlled unit for 2 d before being fed to calves. All colostrum had IgG concentrations >50 g/L and was fed to calves promptly after birth. Blood samples were obtained from calves via the jugular vein at 0 h (before colostrum feeding) and at 24 h of age to determine the rate of passive transfer of IgG; individual calf live-weights were recorded to monitor weight gain (kg/d) from birth to weaning. Colostrum stored in warmer conditions (i.e., 22°C) had >42 times more bacteria present and a pH that was 0.85 units lower and resulted in a serum IgG concentration that was almost 2 times lower compared with colostrum that was pasteurized, untreated, or stored at 4°C for 2 d. Colostrum stored at 4°C for 2 d had more bacteria present than pasteurized and fresh colostrum but did not result in reduced calf serum IgG concentrations. Average daily weight gain from birth to weaning did not differ among treatments. Even if colostrum has sufficient IgG (>50 g/L) but cannot be fed to calves when freshly collected, storage at ≤4°C for 2 d is advisable to ensure adequate passive transfer when it is consumed by the calf.     

Body condition score and body weight effects on dystocia and stillbirths and consequent effects on postcalving performance

The objective of this study was to quantify the effect of periparturient body condition score (BCS) and body weight (BW) related traits on the incidence of calving dystocia and stillbirths, and to determine any consequent effect of dystocia and stillbirths on BCS, BW, milk production, udder health, and fertility in grazing Holstein-Friesian dairy cows. Up to 2,384 lactation records with data on calving dystocia or stillbirths were available from one research herd across 15 yr. Mixed models and generalized estimating equations were used to quantify all effects. Body condition score or BW 8 wk precalving or at calving, or change precalving did not significantly affect the odds of a difficult calving or stillbirth. Cows that experienced dystocia lost, on average, more BCS and BW between calving and nadir and had significantly reduced nadir BCS and BW. Incidence of stillbirths did not affect BCS in early lactation, although BW loss postpartum was greater following a stillbirth. A dystocia or stillbirth event was associated with reduced 60-d milk yield (42 and 52 kg less milk produced following a difficult calving or a stillbirth, respectively). The effect of stillbirth on milk yield was independent of dystocia. Cows that experienced dystocia had reduced milk concentration of fat, protein, and lactose, whereas average somatic cell score (natural logarithm of somatic cell count) in the first 60-d postpartum was elevated. There was no significant effect of dystocia or stillbirth on clinical mastitis, but pregnancy rates to first service and throughout the 12-wk breeding season were compromised in cows that had experienced difficulty at calving. The significance of the effects of stillbirth on somatic cell score and reduced fertility were mediated through its association with dystocia. In conclusion, periparturient BCS and BW within the range observed in the current study did not significantly affect incidence of dystocia and stillbirth, but these events negatively affected cow performance in early lactation.     

Use of electrical stimulation, hot processing and carrageenan for processing low-fat ground beef patties

Three studies were conducted to determine the effects of electrical stimulation, hot processing and carrageenan usage on sensory, shear force and cooking properties of low-fat (5, 10%) beef patties. The right or left sides of beef carcasses assigned to electrical stimulation (ES) received 600 V pulsating current for 120 s. Non-stimulated (NS) sides were also included for comparisons. Sides subjected to hot processing (HP) were boned 90 min post-exsanguination. Cold processing (CP) was initiated 48 h post mortem. Formulations for the manufacture of patties included the use of carrageenan [none, 0.5% iota (ι), 0.5% kappa (κ)]. Patties from NSHP beef had higher pH and cooking yields, less shrink in patty dimensions during cooking and lower shear force values than patties from NSCP controls (P < 0.05). ES improved tenderness and juiciness of CP patties, while ESHP patties exhibited higher cooking yields than NSCP patties. Tenderness was improved in two of the three studies as a result of increasing the fat content from 5 to 10%. Use of ι-carrageenan provided improvements in tenderness and juiciness over patties receiving no carrageenan or κ-carrageenan. Processors should consider HP with 1.0% added salt (improved cooking yields, patty configuration, tenderness) and the use of ι-carrageenan (improved tenderness and juiciness) for low-fat beef patties.     

Profiling with AspectJ

This paper investigates whether AspectJ can be used for efficient profiling of Java programs. Profiling differs from other applications of AOP (e.g. tracing), since it necessitates efficient and often complex interactions with the target program. As such, it was uncertain whether AspectJ could achieve this goal. Therefore, we investigate four common profiling problems (heap usage, object lifetime, wasted time and time‐spent) and report on how well AspectJ handles them. For each, we provide an efficient implementation, discuss any trade‐offs or limitations and present the results of an experimental evaluation into the costs of using it. Our conclusions are mixed. On the one hand, we find that AspectJ is sufficiently expressive to describe the four profiling problems and reasonably efficient in most cases. On the other hand, we find several limitations with the current AspectJ implementation that severely hamper its suitability for profiling. Copyright © 2006 John Wiley & Sons, Ltd.     

Holstein-Friesian strain and feed effects on milk production, body weight, and body condition score profiles in grazing dairy cows

Data from 113 lactations across 76 cows between the years 2002 to 2004 were used to determine the effect of strain of Holstein-Friesian (HF) dairy cow and concentrate supplementation on milk production, body weight (BW), and body condition score (BCS; 1 to 5 scale) lactation profiles. New Zealand (NZ) and North American (NA) HF cows were randomly allocated to 1 of 3 levels of concentrate supplementation [0, 3, or 6 kg of dry matter (DM)/cow per d] on a basal pasture diet. The Wilmink exponential model was fitted within lactation (Y_DIM = a + b e(^{−0.05 × DIM)} + c × DIM). The median variation explained by the function for milk yield was 86%, between 62 and 69% for milk composition, and 80 and 70% for BW and BCS, respectively. North American cows and cows supplemented with concentrates had greater peak and 270-d milk yield. Concentrate supplementation tended to accelerate the rate of incline to peak milk yield, but persistency of lactation was not affected by either strain of HF or concentrate supplementation. No significant strain by diet interaction was found for parameters reported. New Zealand cows reached nadir BCS 14 d earlier and lost less BW (22 kg) postcalving than NA cows. Concentrate supplementation reduced the postpartum interval to nadir BW and BCS, and incrementally increased nadir BCS. New Zealand cows gained significantly more BCS (i.e., 0.9 × 10⁻³ units/d more) postnadir than NA cows, and the rate of BCS replenishment increased linearly with concentrate supplementation from 0.5 × 10⁻³ at 0 kg of DM/d to 0.8 × 10⁻³ and 1.6 × 10⁻³ units/d at 3 and 6 kg of DM/d concentrates, respectively. Although there was no significant strain by diet interaction for parameters reported, there was a tendency for a strain by diet interaction in 270-d BCS, suggesting that the effect of concentrate supplementation on BCS gain was, at least partly, strain dependent.     

Ultrahigh molecular weight polyethylene as used in articular prostheses (a molecular weight distribution study)

Currently there is widespread use of ultrahigh molecular weight polyethylene (UHMWPE) acetabular components in total joint replacement prostheses. What has been most surprising about the wear of UHMWPE under such circumstances is the occurrence of brittle fracture. Such fracture had not been observed in the usual engineering tests done in the laboratory on UHMWPE. It was only when prosthese which had been removed from patients were examined or run in hip joint simulators with serum or synovial fluid as the lubricant, that brittle fracture was encountered. The problem of environment-enhanced brittle fracture in plastics dates back to 1946. Interestingly, the phenomenon was first described in polyethylene. The prime variables involved are polymer molecular weight, sensitizing environment, stress filed, and temperature. Other things being equal, brittle behavior in polyethylene is extremely sensitive to the amount of low molecular weight polymer present. In the light of the foregoing we have studied the molecular weight distribution in six commercially available UHMWPE components. These were obtained from six different manufacturers. The specimens were characterized both on their bearing (wear) surfaces and in their interior bulk. The results obtained indicate that:

• 1 The UHMWPE components contain substantial amounts of low molecular weight polymer.
• 2 The UHMWPE components differ significantly in molecular weight distribution.
• 3 The UHMWPE components contain substantial amounts of crosslinked polymer.

     

Gradient interpenetrating polymer networks. I. Poly(ether urethane) and polyacrylamide IPN

The swelling properties of poly(ether urethane)s and the preparation of interpenetrating polymer networks (IPNs) from a poly(ether urethane) thermoplastic elastomer and hydrogel forming polyacrylamide have been studied. The acrylamide monomer was polymerized with simultaneous crosslink formation, in the presence of the swollen thermoplastic elastomer. Upon removal of the swelling solvent, an IPN was obtained which absorbed water in the manner of a hydrogel but had mechanical properties superior to a hydrogel.