Effects of prepartum intramammary antibiotic therapy on udder health, milk production, and reproductive performance in dairy heifers

Preparturient heifers (n = 561) from 9 herds in 6 US states and 1 Canadian province were enrolled in a study to test the hypothesis that prepartum intramammary therapy would cure existing intramammary infections (IMI) and lead to increased milk production, reduced linear somatic cell count (LSCC), and improved reproductive performance. Mammary secretions were collected 10 to 21 d before expected calving from each quarter. Heifers were then assigned by identification number to receive intramammary therapy consisting of infusion of one tube per mammary quarter of a lactating cow commercial antibiotic preparation containing cephapirin or to a nontreated control group. Overall, 34.1% of mammary quarters were infected with a mastitis pathogen before parturition and 63.4% of heifers had at least one mammary quarter infected. The coagulase-negative staphylococci (CNS) caused the majority (74.8%) of prepartum IMI. Coagulase-positive staphylococci, environmental streptococci, and coliforms accounted for 24.5% of prepartum infections. Treatment had a significant effect on the cure rate of infected mammary quarters. Mammary quarters that were infected prepartum and treated with antibiotics had a 59.5% efficacy of cure rate and the percentage reduction in heifers with IMI was 51.9. Control quarters had a spontaneous cure rate of 31.7%. Treatment did not significantly affect milk production or LSCC in the first 200 d of lactation; however, there was a significant treatment by herd interaction for milk production. Quarters cured of either CNS or major pathogens had a lower LSCC in the first 200 d of lactation. No significant effect on services per conception or days open between treatment and control groups was observed. This trial demonstrated that prepartum intramammary antibiotic therapy did reduce the number of heifer IMI postpartum. Milk production, LSCC, and reproductive performance during the first 200 d of the first lactation were not significantly affected by treatment. Given these results, use of prepartum intramammary antibiotic therapy in heifers as a universal strategy to increase milk production in first-lactation dairy cows may not be warranted.     

Effects of rumen-protected choline and monensin on milk production and metabolism of periparturient dairy cows

Choline and monensin may be supplemented during the transition period with the objectives of aiding in fat metabolism and improving energy balance, respectively. The objectives of this study were to determine the effects of supplementing rumen-protected choline (RPC) and monensin in a controlled-release capsule (CRC) on metabolism, dry matter intake, milk production, and liver function in transition dairy cattle. Three weeks before expected calving, 182 Holsteins were randomly assigned to receive one of the following: a monensin CRC, 56 g/d of RPC until 28 d in milk, CRC + RPC, or neither supplement (control). Blood samples were collected at enrollment, 1 wk before calving, and in the first and second weeks after calving. Liver biopsies were obtained from multiparous cows randomly selected from each treatment group within 24 h and again 3 wk postpartum. Daily milk production was recorded through 60 d in milk. There were no interactions of the effects of RPC and CRC on any of the outcomes measured. Overall, cows that received RPC produced 1.2 kg/d more milk in the first 60 d of lactation, but this effect was attributable to an increase in milk production of 4.4 kg/d among cows with a body condition score ≥4 at 3 wk before calving; fat cows that received RPC ate 1.1 kg of DM/d more from wk 3 before calving through wk 4 after calving. Monensin supplementation significantly increased serum concentrations of glucose and urea, lowered concentrations of β-hydroxybutyric acid and aspartate aminotransferase in the peripartum period, and increased liver glycogen content at 3 wk into lactation. The metabolic effects of CRC are consistent with previous studies, and the effects on liver are novel. The mechanism by which RPC increased milk production was not revealed in this study and merits further research.     

德阳松柏村典型液化震害剖析

2008 年 5 月 12 日中国发生的 8.0 级汶川大地震中, 位于 Ⅶ 、 Ⅷ 度交接处的德阳松柏村液化破坏十分明显, 喷砂类型丰富,液化伴随大量地裂缝,液化加震现象十分显著 , 具有典型研究价值。对该村进行了详细的现场测试并 与以往液化震害进行了对比分析,结果表明： 尽管松柏村地表主要喷出物是中砂和粗砂,但实际液化土与喷出物差别显著,主要为砂砾土液化;以往还没有提出过适于工程应用的砂砾土液化判别方法,而超重型动力触探（ DPT ）具有设备简单、经济实用、测试数据连续的优点,可作为砂砾土液化预测的核心指标; 松柏村大量地裂缝现象不是由次断层造成而是由土层液化引起,而液化产生地裂缝的基本条件为地表较平坦（ <3% ）以及液化土层水平分布不均匀; 液化减震的基本条件为上覆非液化层足够厚且较为密实,但定量评价方法还有待进一步研究。     

Marine cloud brightening

The idea behind the marine cloud-brightening (MCB) geoengineering technique is that seeding marine stratocumulus clouds with copious quantities of roughly monodisperse sub-micrometre sea water particles might significantly enhance the cloud droplet number concentration, and thereby the cloud albedo and possibly longevity. This would produce a cooling, which general circulation model (GCM) computations suggest could-subject to satisfactory resolution of technical and scientific problems identified herein-have the capacity to balance global warming up to the carbon dioxide-doubling point. We describe herein an account of our recent research on a number of critical issues associated with MCB. This involves (i) GCM studies, which are our primary tools for evaluating globally the effectiveness of MCB, and assessing its climate impacts on rainfall amounts and distribution, and also polar sea-ice cover and thickness; (ii) high-resolution modelling of the effects of seeding on marine stratocumulus, which are required to understand the complex array of interacting processes involved in cloud brightening; (iii) microphysical modelling sensitivity studies, examining the influence of seeding amount, seed-particle salt-mass, air-mass characteristics, updraught speed and other parameters on cloud-albedo change; (iv) sea water spray-production techniques; (v) computational fluid dynamics studies of possible large-scale periodicities in Flettner rotors; and (vi) the planning of a three-stage limited-area field research experiment, with the primary objectives of technology testing and determining to what extent, if any, cloud albedo might be enhanced by seeding marine stratocumulus clouds on a spatial scale of around 100×100 km. We stress that there would be no justification for deployment of MCB unless it was clearly established that no significant adverse consequences would result. There would also need to be an international agreement firmly in favour of such action.     

Strong,Tough, Electrospun Polymer–Nanotube Composite Membranes with Extremely Low Density

Electrospinning has been used to produce porous, low density, polymer–nanotube composite membranes. The membrane mechanical properties can be enhanced by tuning the nanotube content, aligning the fibers during spinning, and by post production drawing. The mechanical properties are maximized for membranes with a nanotube content of 0.43 vol %. Aligned composites at this volume fraction have been prepared by spinning onto a rotating drum collector electrode. This method results in significant increases in modulus, strength, and toughness. The best composites, produced at the maximum drum rotation rate, were post treated by a drawing step to result in further increases in modulus and strength. These methods allows the production of membranes with densities as low as ～340 kg m^?3 but with values of stiffness, strengths and toughness's more typically found in bulk thermoplastics; 1.2 GPa, 40 MPa, and 13 J g^?1.     

Shear stress in a pressure‐driven membrane system and its impact on membrane fouling from a hydrodynamic condition perspective: a review

Pressure‐driven membrane technology has gained increasing popularity in municipal/domestic and industrial wastewater treatment, desalination, and water reclamation. Careful manipulation of surface shear stress, which plays a vital role in membrane fouling control from a purely hydrodynamic perspective, can minimise concentration polarisation of solute on flat sheet membranes, or enhance the particle back transport from hollow fibre membranes. This review considers the techniques to generate turbulence and shear at the membrane surface, the magnitude of shear stress, and the experimental, as well as numerical methods for evaluation of shear stress. The findings are presented in terms of the amount of shear stress reported to control membrane fouling in these systems. Operational disadvantages of fouling control via application of shear stress occur while changing the properties of the solute or particles, such as cell breakup, bacterial population change, or shear stress classification. The literature teaches that future developments on shear stress for membrane systems must be addressed, in addition to energy consumption, shear stress distribution and the development of combined analytical methods to characterise and visualise shear in situ for different membrane configurations. © 2016 Society of Chemical Industry     

Solving scheduling tournament problems using a new version of CLONALG

The travelling tournament problem (TTP) is an important and well-known problem within the collective sports research community. The problem is NP-hard which makes difficult finding quality solution in short amount of time. Recently a new kind of TTP has been proposed ‘The Relaxed Travelling Tournament Problem’. This version of the problem allows teams to have some days off during the tournament. In this paper, we propose an immune algorithm that is able to solve both problem versions. The algorithm uses moves which are based on the team home/away patterns. One of these moves has been specially designed for the relaxed travel tournament instances. We have tested the algorithm using well-known problem benchmarks and the results obtained are very encouraging.