美国控制温室气体排放的市场化政策选择

在历史上,美国习惯于采用指挥与控制法来减少污染物排放。然而,这种规制措施会降低产业部门的生产效率。文章引入基于市场机制的两种碳价政策,一是碳税,二是总量控制与交易计划,并对这两种政策选择的设计进行了探讨,对二者在不确定性条件下的减排效果、促进政府税收、加强行政管理等方面的差异进行了比较,认为采用一种将碳税和总量控制与交易计划结合在一起的综合性碳价政策,在效率和分配方面要优于指挥与控制法。     

谷歌盈利能否持续增长？

业绩有所恢复，但仍不尽如人意，至少对谷歌公司而言是不够的.     

几种二倍频噐的相位噪声

以往对放大噐和倍频噐相位噪声的研究表明,有一种称为“P—N 结相位噪声的闪烁效应规律”。使用低噪声晶体管的倍频器与此规律有矛盾。将有特基二极管倍频噐和电子管倍频噐与 P—N 结噐件作了比较。由于电子管倍频噐的相位噪声不因负反馈而变化,这表明电子管本身的相位噪声可能远比观察到的要小。晶本管倍频噐的相位噪声随负反馈量的增加而逐渐减小到一个下限,即使再增加负反馈量,噪声将保持恒定。对所有倍频噐在2Hz～5KHz 内的相位噪声进行了测量,并将测量结果外推到1Hz。研究过程中,研制了一低闪烁噪声低漂移的前置直流放大噐。     

五个维度理解第四次工业革命

我们将会和更加智能的机器一同工作,只有不断提升自己才能免于被技术所取代。我们也要着眼于那些我们之所以为人,而不是机器的特质,尤其是同理心、灵感、归属感、创意以及敏感性等等的特点整个世界正处于“第四次工业萆命”的初期。这个阶段的表现形式是：在物质世界、数字世界与人类自身相融合的驱动下,我们的生产方式、     

在不确定性增大的环境中如何实现货币政策双目标?北大核心

美国国内经济虽然存在波动,但仍然比较稳固。但全球经济和金融市场的不确定性增加令美国经济面临的风险增加,美联储应结合经济数据,审慎地进行加息。美联储可能会在必要时实施"非常规政策",引导长期利率下行。     

A randomized trial to assess the effectiveness of an infant home safety programme

The aim of this study was to test an intervention aimed at addressing the risk of injury in infants 2 - 12 months of age. A non-blinded, randomized controlled trial was conducted, whereby parents were randomly assigned to either a control or one of two intervention groups. Parents completed questionnaires regarding safety behaviours and injuries at the 2 (baseline), 6 and 12 month immunization visit at the community health unit. During the 2 month visit to the health unit, the two intervention groups received a home safety kit containing nine items, an instructional brochure and a risk assessment checklist. Subjects randomized to the safety kit plus home visit group also received a standardized home visit from a community health nurse. Two of the 14 parental safety behaviours showed a significant increase in use among parents in the intervention groups. Neither of the interventions was associated with a reduction in parent-reported injuries among children. It was concluded that home visitation may provide a beneficial adjunct to the provision of safety devices and may increase use by parents.