First Sagittarius A* Event Horizon Telescope Results. VIII. Physical Interpretation of the Polarized Ring

In a companion paper, we present the first spatially resolved polarized image of Sagittarius A* on event horizon scales, captured using the Event Horizon Telescope, a global very long baseline interferometric array operating at a wavelength of 1.3 mm. Here we interpret this image using both simple analytic models and numerical general relativistic magnetohydrodynamic (GRMHD) simulations. The large spatially resolved linear polarization fraction (24%–28%, peaking at ∼40%) is the most stringent constraint on parameter space, disfavoring models that are too Faraday depolarized. Similar to our studies of M87*, polarimetric constraints reinforce a preference for GRMHD models with dynamically important magnetic fields. Although the spiral morphology of the polarization pattern is known to constrain the spin and inclination angle, the time-variable rotation measure (RM) of Sgr A* (equivalent to ≈46° ± 12° rotation at 228 GHz) limits its present utility as a constraint. If we attribute the RM to internal Faraday rotation, then the motion of accreting material is inferred to be counterclockwise, contrary to inferences based on historical polarized flares, and no model satisfies all polarimetric and total intensity constraints. On the other hand, if we attribute the mean RM to an external Faraday screen, then the motion of accreting material is inferred to be clockwise, and one model passes all applied total intensity and polarimetric constraints: a model with strong magnetic fields, a spin parameter of 0.94, and an inclination of 150°. We discuss how future 345 GHz and dynamical imaging will mitigate our present uncertainties and provide additional constraints on the black hole and its accretion flow

Differential pricing strategy in improving access to medicine in developing countries

Background Inadequate access to medicine is a key public health issue. It violates the basic human right, and impedes economics development and social progress. Differential pricing means to charge according to variant ability to pay for the same products. Since differential pricing has been successfully used into many business sectors, its adoption in pharmaceutical industry seems to be necessary and feasible to help improve access to medicine for developing countries. Objective This project is to review the effect of “differential pricing “in pharmaceutical industry and to discuss its current situation and future development. Methodology A literature review was conducted on this topic. Keywords of “(Tiered OR differential OR segment*) AND (price*) AND (developing countries) AND (pharmacy OR drug OR medicine OR vaccine)” were used in databases of Pubmed, Medline and Google scholar for relevant studies and reports on differential pricing in pharmaceutical or vaccine markets. Result A total of 16 papers were included into this systematic review. In theory, differential pricing is a “win-win” solution with the ability to reconcile both static and dynamic costs. In practice, differential pricing works to help improve access, however, lower tiered price for patent drugs is still more expensive than generic drugs in most cases. Conclusion Differential pricing strategy has the potential to improve access to medicine. However it is still in an infancy stage, there are still lots of spaces for further improvement. Except for pricing policies, other mutual supportive policies also need to obtain a better access to medicine in developing countries.published_or_final_versionPublic HealthMasterMaster of Public Healt

澜沧江湄公河中上游淡水鱼类多样性

澜沧江&ndash;湄公河是东南亚最大的河流,也是世界上淡水生物多样性最高的三大河流之一。由于特殊的地理位置和国际河流属性,澜沧江&ndash;湄公河淡水鱼类的多样性现状仍缺乏系统的认识。本文在近20年调查的基础上,系统整理了澜沧江&ndash;湄公河中上游32个支流或亚流域的淡水鱼类物种名录,在此基础上对其种类组成和分布进行了分析,并利用分类学多样性指数对澜沧江&ndash;湄公河中上游流域的物种多样性进行了评估。结果表明,澜沧江&ndash;湄公河中上游共记录了淡水鱼类745种,分属于2纲17目63科229属,其中鲤形目鱼类451种,占物种数的60.5%。分类学多样性指数显示,从源头到中游,淡水鱼类在分类阶元上的分布越来越均匀,亲缘关系越来越远,分类多样性越来越高。聚类分析(cluster analysis,CA)和多维尺度分析(multi-dimensional scaling,MDS)表明,当Jaccard相似性系数为8.69时,澜沧江&ndash;湄公河中上游32个亚流域可以分为源区、上游和中游3组;相似性分析(ANOSIM)结果显示,各组之间淡水鱼类组成差异显著(R = 0.877,P = 0.001)。相似性百分比分析(similarity percentage analysis,SIMPER)结果表明,导致3组差异性的鱼类主要是鲤形目和鲇形目鱼类,且随着地势阶梯的升高出现了科级、属级类群的替代。近几十年来,随着流域各国人口的增长和经济的快速发展,澜沧江&ndash;湄公河鱼类多样性和渔业资源面临严重威胁,未来需加强流域内国家间合作,在流域尺度上制定科学保护计划。</p

澜沧江湄公河中上游淡水鱼类多样性

澜沧江–湄公河是东南亚最大的河流,也是世界上淡水生物多样性最高的三大河流之一。由于特殊的地理位置和国际河流属性,澜沧江–湄公河淡水鱼类的多样性现状仍缺乏系统的认识。本文在近20年调查的基础上,系统整理了澜沧江–湄公河中上游32个支流或亚流域的淡水鱼类物种名录,在此基础上对其种类组成和分布进行了分析,并利用分类学多样性指数对澜沧江–湄公河中上游流域的物种多样性进行了评估。结果表明,澜沧江–湄公河中上游共记录了淡水鱼类745种,分属于2纲17目63科229属,其中鲤形目鱼类451种,占物种数的60.5%。分类学多样性指数显示,从源头到中游,淡水鱼类在分类阶元上的分布越来越均匀,亲缘关系越来越远,分类多样性越来越高。聚类分析(cluster analysis,CA)和多维尺度分析(multi-dimensional scaling,MDS)表明,当Jaccard相似性系数为8.69时,澜沧江–湄公河中上游32个亚流域可以分为源区、上游和中游3组;相似性分析(ANOSIM)结果显示,各组之间淡水鱼类组成差异显著(R = 0.877,P = 0.001)。相似性百分比分析(similarity percentage analysis,SIMPER)结果表明,导致3组差异性的鱼类主要是鲤形目和鲇形目鱼类,且随着地势阶梯的升高出现了科级、属级类群的替代。近几十年来,随着流域各国人口的增长和经济的快速发展,澜沧江–湄公河鱼类多样性和渔业资源面临严重威胁,未来需加强流域内国家间合作,在流域尺度上制定科学保护计划

Family Harmony，Ownership Concentration，and Corporate Performance of Family Business

【中文摘要】本文以2011 ～ 2013年沪深两市的家族企业为研究对象，以家族凝聚力、家族宪法等协调机制及家族与经理人关系度量家族和谐程度，以赫芬达尔 — 赫希曼指数度量股权集中度，实证研究家族和谐及股权集中度对家族企业绩效的影响。研究发现：家族和谐程度与家族企业绩效呈正相关关系，当家族越和谐时，即家族凝聚力越强，家族宪法等协调机制发挥越好，家族与经理人和谐 程度越高，家族企业绩效越好；家族股权集中度与家族企业绩效呈倒U形关系，只有当家族成员的股权集中度处在一个适度的范围内，家族企业绩效才能达到最优；家族和谐程度对二者间的关系起到了正向的调节作用。 【Abstract】This paper studies a sample of family firms that have been listed in Shanghai and Shenzhen stock exchanges for five years. We use family cohesion and coordination mechanisms such as family constitutions to measure family harmony, use Herfindahl-Hirschman index to measure ownership concentration, and perform an empirical analysis of the effects of family harmony and ownership concentration on family firm performance. The results show：①family harmony is positively associated with family firm performance. That is, the more harmonious the family is, i.e.，the stronger the family cohesion is, the better coordination mechanisms such as family constitution are；the more harmonious the relationship between family and managers is,the better the performance of family business is；②ownership concentration and family firm performance exhibit an inverted U-shaped relationship. Family business performs the best when the ownership concentration of family members is in a moderate range；③the degree of family harmony positively moderates the relationship between ownership concentration and family firm performance．本文的研究得到国家自然科学基金青年基金“虚拟企业协同设计成本控制研究”（70702021）的资助

威布尔分布随机载荷下风电机组行星轮系疲劳强度分析

为了快速准确地评估风电机组行星轮系疲劳寿命，根据行星轮系输入转矩与风速的分布关系，编制了不同风速下对应的二参数威布尔随机载荷谱，并用雨流计数法对载荷谱进行统计处理；在ANSYS中对行星轮轮系进行有限元分析，得到齿轮结构应力响应；依据Minner线性累积损伤理论，结合nCodeDesignLife对行星轮系进行疲劳寿命估算。着重分析了风电机组在启动风速、额定风速及年平均风速工况下的行星轮系疲劳寿命，获得各齿轮疲劳损伤状况，为风电机组行星轮系疲劳强度设计提供理论依据

斜齿轮裂纹应力强度因子与<italic>J</italic>积分的计算分析

探究了含三维裂纹斜齿轮应力强度因子及J积分在不同初始裂纹参数条件下的数值曲线分布规律。运用有限元软件对含初始裂纹的斜齿轮进行了数值分析，模拟求解齿根椭圆形裂纹尖端3种类型的应力强度因子及J积分，分析了3种应力强度因子与J积分随裂纹长度、裂纹角度、裂纹位子等初始裂纹参数的变化规律。研究表明，改变不同的初始裂纹参数数据时，所的对应的3种应力强度因子与J积分的曲线图有着很明显的变化规律

Liquid strengthening adhesive for laser shock peening sacrificial layer and application of liquid strengthening adhesive in laser shock peening

本发明公开了一种用于激光冲击强化牺牲层的液体强化胶及其在激光冲击强化中的应用，属于激光冲击强化技术领域。该液体强化胶的原料组成：丁腈橡胶为20‑40％；苯乙烯为30‑50％；全氯乙烯5‑15％；二氧化硅5‑15％；炭黑0.5％‑1％。该液体强化胶在激光冲击强化中的应用过程为：先根据激光冲击强化工艺参数计算工件表面待强化区域所需液体牺牲层的体积，在待加工区域进行液体强化胶的涂覆，凝固后进行激光冲击强化；撕掉凝固后的牺牲层，完成强化过程。本发明牺牲层与传统激光冲击强化牺牲层黑胶或者铝箔相比可以更好的强化复杂曲面，更有利于工程运用

Liquid strengthening adhesive for laser shock peening sacrificial layer and application of liquid strengthening adhesive in laser shock peening

本发明公开了一种用于激光冲击强化牺牲层的液体强化胶及其在激光冲击强化中的应用，属于激光冲击强化技术领域。该液体强化胶的原料组成：丁腈橡胶为20‑40％；苯乙烯为30‑50％；全氯乙烯5‑15％；二氧化硅5‑15％；炭黑0.5％‑1％。该液体强化胶在激光冲击强化中的应用过程为：先根据激光冲击强化工艺参数计算工件表面待强化区域所需液体牺牲层的体积，在待加工区域进行液体强化胶的涂覆，凝固后进行激光冲击强化；撕掉凝固后的牺牲层，完成强化过程。本发明牺牲层与传统激光冲击强化牺牲层黑胶或者铝箔相比可以更好的强化复杂曲面，更有利于工程运用

Liquid strengthening adhesive for laser shock peening sacrificial layer and application of liquid strengthening adhesive in laser shock peening

本发明公开了一种用于激光冲击强化牺牲层的液体强化胶及其在激光冲击强化中的应用，属于激光冲击强化技术领域。该液体强化胶的原料组成：丁腈橡胶为20‑40％；苯乙烯为30‑50％；全氯乙烯5‑15％；二氧化硅5‑15％；炭黑0.5％‑1％。该液体强化胶在激光冲击强化中的应用过程为：先根据激光冲击强化工艺参数计算工件表面待强化区域所需液体牺牲层的体积，在待加工区域进行液体强化胶的涂覆，凝固后进行激光冲击强化；撕掉凝固后的牺牲层，完成强化过程。本发明牺牲层与传统激光冲击强化牺牲层黑胶或者铝箔相比可以更好的强化复杂曲面，更有利于工程运用