基于三维技术的《机械制图》教学改革探讨

《机械制图》是各层次工科类大学机械类专业和近机械类专业必修的、高度实践性的一门技术基础课。目前流行的几种三维CAD软件,可以满足包括三维造型与三维设计、计算机辅助工程分析、机构运动分析与仿真、装配干涉检验、三维转二维、图样档案管理等各种应用需要。随着先进的三维设计、制造手段和技术应用的不断发展,相应的《机械制图》课程的各个知识结构部分的教学方法、教学手段等方面的改革势在必行。     

芪柏塌渍治疗小儿静脉炎的疗效及对TLR-4/核因子-κB信号通路的影响

目的观察芪柏塌渍对静脉炎的疗效,同时探讨其对TLR-4/核因子-κB信号通路上标志蛋白表达的影响。方法选取2018年1月至2019年6月大连市中心医院收治的40例静脉炎患儿作为研究对象,按随机数字表法分为常规组和试验组,各20例,另取20例健康儿童为对照组。对照组患儿取50%硫酸镁溶液浸湿的无菌纱布敷于发生静脉炎处,面积以超过静脉炎范围1~2 cm为宜,并用保鲜膜包裹于纱布外,每2小时换药1次,3 d为一个治疗周期。试验组用无菌棉签蘸取适量芪柏塌渍膏涂于发生静脉炎处,面积以大于静脉炎范围1~2 cm为宜,厚度0.2~0.5 cm,予以无菌纱布覆盖,最后用胶布固定,每4~6小时换药1次,3 d为一个治疗周期。于治疗前及治疗2个周期时,采用蛋白免疫印迹法检测外周血中TLR-4和核因子-κB水平变化,酶联免疫吸附试验(ELISA)检测患儿血清肿瘤坏死因子-α(TNF-α)、白细胞介素-11(IL-11)、白细胞介素-4(IL-4)、白细胞介素-33(IL-33)蛋白表达。结果治疗后两组患儿数字评分法(NRS)评分、红肿面积有所改善,且试验组改善程度优于常规组,差异有统计学意义(P<0.05);静脉炎患儿血清TLR-4、核因子-κB、TNF-α、IL-11、IL-4、IL-33水平明显高于健康对照组(P<0.05);治疗后,常规组和试验组患儿TLR-4、核因子-κB、TNF-α、IL-11、IL-4、IL-33水平明显下降(P<0.05),且试验组上述指标明显低于常规组(P<0.05)。结论静脉炎患儿存在TLR-4/核因子-κB信号通路表达紊乱,芪柏塌渍可明显调节TLR-4/核因子-κB信号通路上标志性蛋白的表达,该效应可能是芪柏塌渍从机体炎症方面改善静脉炎患儿的作用机制之一。     

Biases in fiscal multiplier estimates

The size of fiscal multipliers is intensively debated as large (small) multipliers provide arguments to expand (cut) public spending. We use data on multiplier estimates from over a hundred scholarly studies, and ask whether the national imprint and various incentives that the authors face can help explain the large observed variance in these estimates. We complement this meta-analytical data with information on economists’ personal characteristics collected from their biographies and through a self-conducted survey. Our evidence is consistent with the hypothesis that national background and policy orientation of researchers matter for the size of multiplier estimates. We only find weak support for the hypothesis that the interests of donors financing the research are relevant. Significant biases largely disappear for teams of international co-authors.     

A new economics approach to modelling policies to achieve global 2020 targets for climate stabilisation

This paper explores a Post Keynesian, ‘new economics’ approach to climate policy, assessing the opportunities for investment in accelerated decarbonisation of the global economy to 2020 following the Great Recession of 2008–2009. The risks associated with business-as-usual growth in greenhouse gas (GHG) concentrations in the atmosphere suggest that avoiding dangerous climate change will require that the world’s energy-economy system is transformed through switching to low-carbon technologies and lifestyles. Governments have agreed a target to hold the increase in temperatures above pre-industrial levels to at most 2°C and have offered reductions by 2020 in GHG emissions or the carbon-intensity of GDP. The effects of policies proposed to achieve pathways to 2020 towards this target are assessed using E3MG, an Energy-Environment-Economy (E3) Model at the Global level. E3MG is an annual simulation econometric model, estimated for 20 world regions over 1972–2006 adopting a new economics approach. Additional low-GHG investment of some 0.7% of GDP, with carbon pricing and other policies, is sufficient to achieve a pathway consistent with a medium chance of achieving the long-term target. GDP is above reference levels because decarbonisation reduces world oil prices and increases investment. Employment is some 0.9% above reference levels by 2020 and public finances are almost unaffected.     

A STATE‐LEVEL ANALYSIS OF BUSINESS CYCLE ASYMMETRY

This paper provides a comprehensive examination of asymmetry in US state‐level business cycles. We consider two different types of asymmetry in the adjustment process of a stationary time series: deepness and steepness. The data used in the study are a comparable set of state‐level coincident indexes (SCIs) developed by the Federal Reserve Bank of Philadelphia. Specifically, results from using the momentum‐threshold autoregressive model provide evidence of asymmetry in the growth rate of 23 SCIs as well as the equivalent national coincident index.     

Incentives and the Sorting of Altruistic Agents into Street‐Level Bureaucracies*

Many street‐level bureaucrats have the dual task of helping some clients, while sanctioning others. We develop a model of a street‐level bureaucracy, and we study the implications of its personnel policy on the self‐selection and allocation decisions of agents who differ in altruism towards clients. When bureaucrats are paid flat wages, they do not sanction, and the most altruistic types sort into bureaucracy. Pay‐for‐performance induces some bureaucrats to sanction, but it necessitates an increase in compensation, which can result in sorting from the top and bottom of the altruism distribution. We also explain why street‐level bureaucrats often experience an overload of clients.     

Investigating regional house price convergence in the United States: Evidence from a pair-wise approach

In this paper we examine long-run house price convergence across US states using a novel econometric approach advocated by Pesaran (2007) and Pesaran et al. (2009). Our empirical modelling strategy employs a probabilistic test statistic for convergence based on the percentage of unit root rejections among all state house price differentials. Using a sieve bootstrap procedure, we construct confidence intervals and find evidence in favour of convergence. We also conclude that speed of adjustment towards long-run equilibrium is inversely related to distance.     

Regime-switching effects of debt on real GDP per capita the case of Latin American and Caribbean countries

In this paper, we try to investigate how the debt and real GDP per capita relationship varies with indebtedness levels and other country characteristics in a balanced panel of 21 developing Latin American and Caribbean countries over the period 1992–2006. The empirical results indicate that there exist two threshold values of 32.88% and 55.89%. The latter is lower than the Maastricht criterion and Stability and Growth Pact of a total external Debt per GDP ratio at 60% in the OECD countries. Both thresholds divide our panel into three regimes. In the middle (stimulus) regime, the Debt per GDP ratio has a positive impact on real GDP per capita, which is consistent with the stimulus view (Eisner, 1984). However, the impact becomes negative and consistent with the crowding-out view (Friedman, 1977, 1985) in the left and right (crowding-out) regimes. Based on our findings, we find no supportive evidence for Ricardian view (Barro, 1989). Therefore, our empirical results have important implications for fiscal policymakers in these Latin American and Caribbean countries.     

从债法视角论倒签提单行为的法律性质

作为国际贸易实践中极为普遍的运输单据欺诈之一,倒签提单行为法律性质的认定在审判实践中往往引起诸多争议。倒签提单行为衍生自国际贸易合同和海上货物运输合同,其本身不能脱离合同而独立存在,因此从债法角度分析倒签提单的法律性质将更为清晰。倒签提单行为的通常情形是违约行为,构成特例侵权行为;倒签提单的行为人在整体上应当承担违约责任,在特例中才能构成违约责任和侵权责任的竞合。     

Gross national happiness as an answer to the Easterlin Paradox?

The Easterlin Paradox refers to the fact that happiness data are typically stationary in spite of considerable increases in income. This amounts to a rejection of the hypothesis that current income is the only argument in the utility function. We find that the happiness responses of around 350,000 people living in the OECD between 1975 and 1997 are positively correlated with the level of income, the welfare state and (weakly) with life expectancy; they are negatively correlated with the average number of hours worked, environmental degradation (measured by SOx emissions), crime, openness to trade, inflation and unemployment; all controlling for country and year dummies. These effects separate across groups in a pattern that appears broadly plausible (e.g., the rich suffer environmental degradation more than the poor). Based on actual changes from 1975 to 1997, small contributions to happiness can be attributed to the increase in income in our sample. Interestingly, the actual changes in several of the ‘omitted variables’ such as life expectancy, hours worked, inflation and unemployment also contribute to happiness over this time period since life expectancy has risen and the others have, on average, fallen. Consequently the unexplained trend in happiness is even bigger than would be predicted if income was the only argument in the utility function. In other words, introducing omitted variables worsens the income-without-happiness paradox.