A 250 μg/week dose of vitamin D was as effective as a 50 μg/d dose in healthy adults, but a regimen of four weekly followed by monthly doses of 1250 μg raised the risk of hypercalciuria

The risk of vitamin D insufficiency is increased in persons having limited sunlight exposure and dietary vitamin D. Supplementation compliance might be improved with larger doses taken less often, but this may increase the potential for side effects. The objective of the present study was to determine whether a weekly or weekly/monthly regimen of vitamin D supplementation is as effective as daily supplementation without increasing the risk of side effects. Participants were forty-eight healthy adults who were randomly assigned for 3 months to placebo or one of three supplementation regimens: 50 μg/d (2000 IU/d, analysed dose 70 μg/d), 250 μg/week (10 000 IU/week, analysed dose 331 μg/week) or 1250 μg/week (50 000 IU/week, analysed dose 1544 μg/week) for 4 weeks and then 1250 μg/month for 2 months. Daily and weekly doses were equally effective at increasing serum 25-hydroxyvitamin D, which was significantly greater than baseline in all the supplemented groups after 30 d of treatment. Subjects in the 1250 μg treatment group, who had a BMI >26 kg/m2, had a steady increase in urinary Ca in the first 3 weeks of supplementation, and, overall, the relative risk of hypercalciuria was higher in the 1250 μg group than in the placebo group (P= 0·01). Although vitamin D supplementation remains a controversial issue, these data document that supplementing with ≤ 250 μg/week ( ≤ 10 000 IU/week) can improve or maintain vitamin D status in healthy populations without the risk of hypercalciuria, but 24 h urinary Ca excretion should be evaluated in healthy persons receiving vitamin D3 supplementation in weekly single doses of 1250 μg (50 000 IU).

Effect of ion nitriding on the microstructure and properties of Maraging steel (250 Grade)

In the present investigation, ion nitriding of Maraging steel (250 grade) has been carried out at three different temperatures i.e., at 435 degrees C, 450 degrees C and 465 degrees C for 10 h duration in order to achieve good wear resistance along with high strength required for the slat track component of aircraft. The microstructure of the base material and the nitrided layer was examined by optical and scanning electron microscope, and various phases present were determined by X-ray diffraction. Various properties, such as, hardness, case depth, tensile, impact, fatigue properties and corrosion resistance were investigated for both un-nitrided and ion-nitrided materials. It is observed that the microstructure of the core material remains unaltered and Fe4N is formed in the hardened surface layer after ion nitriding at all the three temperatures employed. Surface hardness increases substantially after ion nitriding. Surface hardness remains almost the same but case depth increases with the increase in ion nitriding temperature due to greater diffusivity at higher temperatures. Tensile strength, fatigue strength and corrosion resistance are improved but ductility and energy absorbed in impact test decrease on ion nitriding. These results are explained on the basis of microstructural observations. The properties obtained after ion nitriding at 450 degrees C for 10 h are found to be optimum when compared to the other two ion nitriding temperatures.

Accountability for good faith in commercial dealing: The Carter v Boehm legacy 250 years on

In common law jurisdictions such as England, Australia, Canada and New Zealand good faith in contracting has long been recognised in specific areas of the law such as insurance law and franchising, and more recently the implied duties of good faith and mutual trust and convenience in employment contracts have generated a considerable volume of case law. Outside of these areas of law that may be characterised as being strongly‘relational’ in character,the courts in common law jurisdictions have been reluctant to embrace a more universal application of good faith in contracting and performance. However increasingly there are cases which support the proposition that there is a common law duty of good faith of general application to all commercial contracts. Most important in this context is the recent decision of the Supreme Court of Canada in Bhasin v Hrynew.1 However, this matter is by no means resolved in all common law jurisdictions. This article looks at the recent case law and literature and at various legislative incursions including statutes, codes of conduct and regulations impacting good faith in commercial dealings.

Die Herings-Polarstamm-Theorie 250 Jahre alt - und aktuelle Bezüge

250 years ago, in Hamburg a herring polar migration theory was published as part of the "Nachrichten von Island, Grönland und der Straße Davis" from the literary remains of the mayor Dr. Johann Anderson. Based on various sources and capable to answer to the herring questions of the time, this one-stock-migration theory became international hypothesis during the following tenth of years. It still is classified as remarkable because some actual ideas on herring migration were thought already 250 years ago. Abstract DE: In Hamburg wurde vor 250 Jahren eine Polarstamm-Theorie zur Heringswanderung als Teil der Nachrichten von Island, Grönland und der Strasse Davis aus dem Nachlass des Bürgermeisters Dr. Johann Anderson veröffentlicht. Aufbauend auf unterschiedliche Quellen und in der Lage, die damaligen Fragen um den Hering zu beantworten, wurde diese Ein-Stamm-Theorie zur heringswanderung über Jahrzehnte internationale Lehrmeinung. Sie wird auch heute noch als bemerkenswert eingestuft. Denn sie enthielt vor 250 Jahren schon Gedankengänge, die noch aktuell sind.

渤海南部 Lz908 孔250 ka 以来的环境演化研究

本文主要针对 250 ka 以来渤海南部Lz908 孔的沉积序列进行年代学和沉积 学研究，通过年代框架的建立、环境代用指标的意义解读，并与区域和全球变 化相对比，讨论了渤海南部晚中更新世以来的环境过程和驱动因素。主要结论 如下： 1. 沉积物粒度对比试验表明，是否去除碳酸盐，对于渤海南部海岸带沉积 物的粒度分析结果产生了显著的影响。未去除碳酸盐的沉积物样品，显著增加 了黏土粒级、超细粒组分的含量；但就粒度分布而言，是否去除碳酸盐不会改 变粒度分布的基本形态。通过实验对比，我们认为，粒度测量的前处理过程去 除碳酸盐是必要的。 2. 粒度参数的计算方法主要有图解法和矩值法两种，为了比较不同方法计 算结果的差异，利用LZ908 孔岩心，在粒度分析的基础上，综合运用相关分析、 回归分析、聚类分析等统计方法，从参数计算过程、沉积物粒度分布形态（多 峰态粒度特征）等方面讨论了两种参数估计方法对计算结果的可能影响及其影 响因素。结果表明：平均粒径、标准偏差相互替代的程度高，而偏度、峰度相 互替代的程度低，或者不可替代；两者的差异是由各自本身的计算过程引起的， 是沉积物粒度分布特征的一种反映，并且与沉积水动力条件密切相关。 3. 释光年代学的研究表明，钻孔0-25 米内未见大的沉积间断，可以通过线 性内插的方式获得各个层位的年龄。25-54 米的海相地层，因为钻孔位于构造 稳定的沉降区，沉积物源单一，因此通过线性外推获得年龄。确定钻孔海侵层 渤海南部Lz908 孔250 ka 以来的环境演化研究 的底部年龄为为 250 ka。根据建立的渤海地区首条释光标准生长曲线，推测光 释光简单多片再生剂量法的理论测年上限为350 ka。 4. 粒度、磁化率等指标间的关系，以及区域和全球的对比表明：沉积物中 细颗粒组分代表了夏季风的变化，但细颗粒含量增高时，指示了夏季风的强盛， 反之则减弱；粗颗粒组分含量和磁化率与冬季风相关，粗颗粒组分含量增加、 磁化率升高时，代表了冬季风的强盛，反之则弱；与黄土-古土壤序列、石笋氧 同位序列和深海氧同位素序列在轨道尺度上对比良好；沉积序列包含27 ka 和 126 ka 的显著周期成分，暗示了区域环境变化是由太阳辐射驱动控制的。

Vertical temperature structure of 250 m. water layer around Sri Lanka at the tail-end of the north-east monsoon

Data collected during cruises of the Hoyo Maru in Jan-Mar 1975 are analysed. Data is tabulated to show vertical temp profile, surface water temp and temp gradient. Each of these features is discussed. Thermoclines are shown to be established off the coast of India, their depth varying according to time of year. Upwelling off the Cochin coast is discussed. This occurs during Oct-Nov. Surface temp is considerably influenced by the north-east monsoon. The 'clockwise current' (or 'transparent current) characterised by high salinity, high transparency, and rich nutrient conchs, and which prevails in Jan-May brings oceanic water into the Bay of Bengal and sweeps along the Ceylon coast.

250 MHz repetition rate monolithically integrated modulated mode-locked semiconductor laser

We present the first monolithically integrated semiconductor pulse source consisting of a mode-locked laser diode, Mach-Zehnder pulse picker, and semiconductor optical amplifier. Pairs of 5.6 ps pulses are generated at a 250 MHz repetition rate. © 2012 OSA.

Design and testing of a 250 kW medium-speed Brushless DFIG

This paper presents the design and testing of a 250 kW medium-speed Brushless Doubly-Fed Induction Generator (Brushless DFIG), and its associated power electronics and control systems. The experimental tests confirm the design, and show the system's steady-state and dynamic performance. The medium-speed Brushless DFIG in combination with a simplified two-stage gearbox promises a low-cost low-maintenance and reliable drive train for wind turbine applications.

Symmetrical low voltage ride-through of a 250 kW Brushless DFIG

The Brushless Doubly-Fed Induction Generator (Brushless DFIG) shows commercial promise for wind power generation due to its lower cost and higher reliability when compared with the conventional Doubly-Fed Induction Generator (DFIG). In the most recent grid codes, wind generators are required to be able to ride through a low voltage fault and meet the reactive current demand from the grid. Hence, a Low-Voltage Ride-Through (LVRT) capability is important for wind generators which are integrated into the grid. In this paper the authors propose a control strategy enabling the Brushless DFIG to successfully ride through a symmetrical voltage dip. The control strategy has been implemented on a 250 kW Brushless DFIG and the experimental results indicate that LVRT is possible without a crowbar.

Design and testing of a medium-speed 250 kW Brushless DFIG

This paper presents the design and testing of a 250 kW medium-speed Brushless Doubly-Fed Generator (Brushless DFIG), and its associated power electronics and control systems. The experimental tests confirm the design, and show the system's steady-state and dynamic performance. The medium-speed Brushless DFIG in combination with a simplified twostage gearbox promises a low-cost low-maintenance and reliable drive train for wind turbine applications.

Experimental LVRT performance of a 250 kW brushless DFIG

Nowadays, all new wind turbine generators have to meet strict grid codes, especially riding through certain grid faults, such as a low voltage caused by grid short circuits. The Low-Voltage Ride Through (LVRT) capability has become a key issue in assessing the performance of wind turbine generators. The mediumspeed Brushless DFIG in combination with a simplified two-stage gearbox shows commercial promise as a replacement for conventional DFIGs due to its lower cost and higher reliability. Furthermore, the Brushless DFIG has significantly improved LVRT performance when compared with the DFIG due to its inherent design characteristics. In this paper, the authors propose a control strategy for the Brushless DFIG to improve its LVRT performance. The controller has been implemented on a prototype 250 kW Brushless DFIG and test results show that LVRT is possible without a need for any external protective hardware such as a crowbar.

Performance analysis and testing of a 250 kW medium-speed brushless doubly-fed induction generator

This study presents the performance analysis and testing of a 250 kW medium-speed brushless doubly-fed induction generator (DFIG), and its associated power electronics and control systems. The experimental tests confirm the design, and showthe system's steady-state and dynamic performance and grid low-voltage ride- through capability. The medium-speed brushless DFIG in combination with a simplified two-stage gearbox promises a low-cost low-maintenance and reliable drivetrain for wind turbine applications. © The Institution of Engineering and Technology 2013.

Micro-electro-mechanical resonant tilt sensor with 250 nano-radian resolution

This paper reports a high-resolution frequency-output MEMS tilt sensor based on resonant sensing principles. The tilt sensor measures orientation by sensing the component of gravitational acceleration along a specified input axis. A combination of design enhancements enables significantly higher sensitivity for this device as compared to previously reported prototype sensors. The MEMS tilt sensor is calibrated on a manual tilt table over tilt angles ranging over 0-90 degrees with a relatively linear response measured in the range of ±20°(linearity error <2.3%) with a scale factor of approximately 50.06 Hz/degree. The noise-limited resolution of the sensor is found to be approximately 250 nano-radians for an integration time of 0.8 s, which is over an order of magnitude better than previously reported results [1]. © 2013 IEEE.