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In this study, a scatter model is proposed for parallel-, fan-, and cone-beam SPECT imaging. In this model, a photon is allowed to be scattered only once, and the probability of scatter for given angle and energy is computed by using the Klein-Nishina formula. The detector is assumed to have perfect energy resolution. The scatter counts are computed for every projection bin. From the scatter counts, the scatter line source response function and scatter-to-primary ratio (SPR) are obtained. They agree well with those from Monte Carlo (MC) simulation including only single scattering, but deviate from those from full MC simulation including both single and multiple scattering. The deviation depends on the source depth within the medium. For a source depth of 6 cm, the difference of the scatter-to-primary ratio between the model and full MC simulation is less than 7%, while for a 21.6 cm source depth, the difference goes up to 27% for parallel-beam geometry and 32% for cone-beam geometry. Since scatter accounts for 20-40% of the total counts in most clinical studies, the scatter model yields a SPR accuracy that ranges from 3% to 12%. The scatter model provides an effective means to estimate the scatter response with reasonable accuracy, and can be used in developing scatter compensation techniques in parallel- and converging-beam SPECT.

Previous work led to the proposal that the precision feeding of a high-concentrate diet may represent a potential method with which to enhance feed efficiency (FE) when rearing dairy heifers. However, the physiological and metabolic mechanisms underlying this approach remain unclear. This study used metabolomics analysis to investigate the changes in plasma metabolites of heifers precision-fed diets containing a wide range of forage to concentrate ratios. Twenty-four half-sib Holstein heifers, with a similar body condition, were randomly assigned into four groups and precision fed with diets containing different proportions of concentrate (20%, 40%, 60% and 80% based on DM). After 28 days of feeding, blood samples were collected 6 h after morning feeding and gas chromatography time-of-flight/MS was used to analyze the plasma samples. Parameters of oxidative status were also determined in the plasma. The FE (after being corrected for gut fill) increased linearly (P < 0.01) with increasing level of dietary concentrate. Significant changes were identified for 38 different metabolites in the plasma of heifers fed different dietary forage to concentrate ratios. The main pathways showing alterations were clustered into those relating to carbohydrate and amino acid metabolism; all of which have been previously associated with FE changes in ruminants. Heifers fed with a high-concentrate diet had higher (P < 0.01) plasma total antioxidant capacity and superoxide dismutase but lower (P ≤ 0.02) hydroxyl radical and hydrogen peroxide than heifers fed with a low-concentrate diet, which might indicate a lower plasma oxidative status in the heifers fed a high-concentrate diet. Thus, heifers fed with a high-concentrate diet had higher FE and antioxidant capacity but a lower plasma oxidative status as well as changed carbohydrate and amino acid metabolism. Our findings provide a better understanding of how forage to concentrate ratios affect FE and metabolism in the precision-fed growing heifers. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the optimum conditions for calcium oxide (CaO) treatment of anaerobically stored corn stover by in situ and in vitro methods. Four ruminally cannulated, non-lactating, non-pregnant Holstein cows were used to determine the in situ effective degradabilities of dry matter ( ISDMD), organic matter ( ISOMD), neutral detergent fibre ( ISNDFD), in vitro organic matter disappearance ( IVOMD) and gas production in 72 h ( GP72h) of corn stover. A completely randomized design involving a 3 × 3 factorial arrangement was adopted. Ground corn stover was treated with different levels of CaO (3%, 5% and 7% of dry stover) at varying moisture contents (40%, 50% and 60%) and stored under anaerobic conditions for 15 days before analysis. Compared with untreated corn stover, the CaO-treated stover had increased ash and calcium (Ca) contents but decreased aNDF and OM contents. The moisture content, CaO level and their interaction affected (p < 0.01) the content of aNDF, ash and OM, and the ratio of aNDF/ OM. The greatest ISDMD, ISOMD and ISNDFD were observed when stover was treated with 7% CaO and 60% moisture, while no differences (p > 0.01) in these in situ degradability parameters were observed between the stover treated with 5% CaO at 60% moisture content and those treated with 7% CaO at 60% moisture content. Corn stover treated with 5% CaO at 50% moisture had the maximum IVOMD and GP72 h among the treatments, and there was no difference (p > 0.01) between 50% and 60% moisture. Results from this study suggested that 5% CaO applied at 60% moisture could be an effective and economical treatment combination. [ABSTRACT FROM AUTHOR]

In order to improve the high-rate discharge properties of La11.3Mg6.0Sm7.4Ni61.0Co7.2Al7.1(AB3.0) alloy electrodes, the effects of plasma milling (PM) and graphene addition on their electrochemical properties and kinetics have been investigated. It was found that the discharge capacity of AB3.0 at a high discharge current density was significantly improved after the addition of graphene followed by PM for only 10 min. Moreover, the high-rate dischargeability (HRD) and the exchange current density I0 of the alloy electrodes were also increased. The PM technique exhibits obvious advantages for improving the high-rate discharge properties of hydrogen-storage alloys. [ABSTRACT FROM AUTHOR]

Abstract--This paper present a fast algorithm for synthetic aperture radar (SAR) image segmentation based on the augmented Lagrangian method (ALM). The proposed approach considers the segmentation of SAR images as an energy minimization problem in a variational framework. The energy functional is formulated based on the statistical characteristic of SAR images. The total variation regularization is used to impose the smoothness constraint of the segmentation result. To solve the optimization problem efficiently, the energy functional is firstly modified to be convex and differentiable by using convex relaxing and variable splitting techniques, and then the constrained optimization problem is converted to an unconstrained one by using the ALM. Finally the energy is minimized with an iterative minimization algorithm. The effectiveness of the proposed algorithm is validated by experiments on both synthetic and real SAR images. [ABSTRACT FROM AUTHOR]

An apparatus and method that can allow continuous and precise total collection of urine under normal conditions was developed that could satisfy the urinesampling requirement of balance studies, metabolic experiments, and hormone trials of cows and heifers. The apparatus is composed of an anterior urethra, a urine cup, and a collection barrel. Total and precise collection of urine can be achieved without leakage, fecal contamination, or urethra infection. The apparatus hasfew negative effects on the cows and does not influence the cows' normal physiological activities. [ABSTRACT FROM AUTHOR]

We developed a saturated iron-core type 35 kV/90 MVA superconductive fault current limiter and installed the device in a transmission network at Puji substation of China Southern Power Grid for live-grid operation. Innovative design in the iron-core configuration ensures that 'the device has low, impedance in normal power transmission and sufficiently high impedance for a fault current limiting action. A magnetization control circuit allows the iron-core to be saturated or de-saturated depending upon the functional requirements. An energy release and voltage-surge protection unit can promptly discharge the magnetic energy accumulated in the iron-core and suppress the induced and surge voltages of the dc circuit in a current limiting event. This device has been designed to reduce the magnitude of a fault current by about 50%, which will prevent the breaking capacity of the existing circuit breakers in the transmission network from being exceeded in the predictable future. This article presents structural and functional specifications and reports up-to-date live-grid operation data of the device. [ABSTRACT FROM AUTHOR]