Price determinants of bred heifers: Do reputations matter?

Replacement brood cows are among the most significant investments for cow-calf operations, thus crucial to profitability. Many cow-calf producers find it cost effective to purchase replacements from a reliable replacement heifer seller, though by doing so they increase risk of reproductive inefficiency due to unknown characteristics of the heifers. When important information about a product is missing to buyers, a seller can build a reputation over time that acts as signal for quality. Previous work has explored reputation effects in feeder cattle markets, but to our knowledge we are the first to explore reputation effects in bred replacement cattle markets. Using data from an annual replacement heifer sale, we analyze the values of heifer characteristics and test for premiums from reputation development. After controlling for reproductive practices, breed, and other characteristics, we find reputation does not play the role that Shapiro theorized. In this sale, the lot order is strategically chosen and may indicate bred heifer quality to buyers, replacing the need for reputation as a signal. This study highlights the importance of quality signals and regional preferences in bred replacement cattle marketing and lays the empirical groundwork for future studies to test Shapiro's theory.     

外商直接投资对我国出口贸易的影响

改革开放以来，外商直接投资对我国出口贸易产生极大的影响，促进了我国出口贸易量的飞速增长。根据直接投资与贸易关系理论，二者之间主要存在着替代效应和互补效应两个方面。本文从直接投资与贸易关系理论出发，探讨了改革开放以来外商直接投资对我国出口贸易的促进作用和不利影响，并提出相应的政策建议。     

再生细骨料取代率对再生混凝土抗压强度的影响

建筑废弃物经过除杂、二次破碎可以得到粒径范围为0-4.75mm的再生细骨料。本文研究了不同水灰比条件下,再生细骨料取代率对再生混凝土抗压强度的影响。结果表明:当再生细骨料取代率由10%增加到40%时,再生混凝土7天抗压强度逐渐降低。再生混凝土28天抗压强度随着再生细骨料取代率的增加逐渐降低,取代率在50%以下时,28天抗压强度降低幅度较小且满足设计要求。再生细骨料用于实际工程中,其社会效益和经济效益十分可观。     

粮食安全、收入约束与生物燃料替代--基于跨国面板数据的实证研究

根据2000_2010年跨国面板数据,利用随机效应tobit模型研究粮食、环境和能源对全球生物燃料替代化石燃料使用的影响。研究发现：粮食安全程度高的国家生物燃料替代程度较高,而生物燃料的过度发展有可能导致“与粮争地”和国际粮食市场价格上涨,从而危及粮食安全;碳排放强度能促进生物燃料替代水平的提高,但前提是该国具有较高的国民收入水平;能源安全考虑仅仅在发达国家内能影响生物燃料替代。相关结论为各国制定适合本国粮食安全状况和经济发展水平的生物燃料替代目标提供参考依据。     

腰-硬联合麻醉在老年人股骨头置换术中的临床疗效

目的探讨腰-硬联合麻醉在老年人股骨头置换术中的临床疗效。方法回顾性分析2013年11月至2014年11月我院行股骨头置换术的59例老年患者,观察患者麻醉前、麻醉后5、10、30 min心率(HR)、收缩压(SBP)、舒张压(DBP)、动脉血氧分压(Sp O2)变化,术后并随访3 d,记录并发症情况。结果麻醉后患者的5、10、30 min的SBP、DBP与麻醉前比较均降低(P<0.05);各时点HR及Sp O2比较差异均无统计学意义(P>0.05)。优良率为98.3%,术后无恶心呕吐、头痛等麻醉相关并发症。结论腰-硬联合阻滞在老年人股骨头置换术中的麻醉效果明显,安全可靠。     

Comparing post-operative resource consumption following transcatheter aortic valve implantation (TAVI) and conventional aortic valve replacement in the UK

Objective:

To define the in-hospital and 6-month post-discharge resource use, following Transcatheter Aortic Valve Implantation (TAVI) and conventional Aortic Valve Replacement (AVR) surgery within a single UK hospital.

Methods:

A local service evaluation of patients undergoing TAVI or AVR between January 2011 and May 2012 captured data until 6-months post-procedure, collected from hospital records and via a General Practitioner questionnaire. The main end-points were mortality, time in ITU/HDU, hospital length of stay (LoS), discharge destination, re-admission, and post-discharge primary/secondary care resource use. Sub-group analyses were performed for AVR patients aged ≥80 (AVR?≥?80) and with EuroSCORE of ≥10 (AVR ES?≥?10) to allow more direct comparison with ‘TAVI type’ patients.

Results:

Results are given as means (standard deviation) for TAVI (n?=?51), AVR (n?=?188), AVR?≥?80 (n?=?48), and AVR ES?≥?10 (n?=?47), respectively, unless otherwise stated. Age in years was 83.0 (8.1), 71.2 (13.1), 84.1 (2.7), 79.4 (7.1); EuroSCORE was 24.7 (11.9), 8.1 (6.4), 12.0 (6.0), and 16.5 (6.6); post-operative LoS (days) was 11.5 (11.2), 10.9 (10.8), 14.3 (16.7), and 15.2 (17.7). For discharged patients, 0%, 7%, 13%, and 9% had unplanned cardiac-related re-admissions within 30-days of discharge. Time to first readmission was 74.6 (34.0), 35.0 (34.2), 20.8 (9.7), and 22.6 (14.3) days.

Limitations:

This was a single-center retrospective evaluation, not prospectively powered to confirm differences in outcomes.

Conclusions:

Despite TAVI being performed in an older, higher risk population, LoS was similar to AVR. Most strikingly there were no cardiac-related re-admissions within 30-days for TAVI and time to first re-admission was significantly longer. This evaluation suggests that TAVI is clinically appropriate and provides economic advantages in both the hospital and post-discharge setting in this high risk group. Many patients undergoing TAVI are considered unfit for surgery and, hence, TAVI offers a treatment that delivers similar results to traditional AVR without the high risk associated with surgery.     

灌砂法检测路基压实度技术探讨

鉴于灌砂法在路基压实度检测中的广发应用,本文从室内和现场两个角度探讨了灌砂法相关技术问题,为公路工程建设提供参考。     

浅谈换填垫层法在软基处理中的实际运用

详细阐述了有关换土垫层法处理软弱地基的基本性能、计算设计方法,并介绍了该方法处理软弱地基的应用实例,对以后的设计有一定的参考意义。     

利益集团、行为偏好与黄宗羲定律——中国封建王朝更替动因的经济学分析

中国封建社会特殊的社会结构下,封建王朝在其演进过程中,农民集团和官僚集团之间的利益博弈对税赋改革的影响会导致＂黄宗羲定律＂的形成。税赋愈改愈重使得农民在当朝所能获得的效用随时间的推移而降低,从而导致农民预期起义成本的降低,当这种预期成本下降到一定水平后,农民集团会采取有效的集团行动并转向对新的政治体制的寻求,最终完成朝代的更替。这一过程可以运用经济学的基本理论,并建立适当模型,从而对中国社会特有的王朝更替现象进行解释。     

浅析不良地基处理方法

在长期的建筑物施工过程中,经常会遇见软弱不良的地基。这种地基会导致建筑物沉降量过大,沉降时间过久且具有很大的不均匀性。因此在建筑施工过程中必须重视对不良软弱地基的加固和处理,以避免建筑物产生不均匀沉降,保证工程质量和建筑物的使用寿命。