关于地勘工作体制改革的探讨

我国地质勘查工作发展的总体方向应该指向何处?地质勘查工作体制现状存在哪些积弊?地质勘查工作新体制总体框架应该如何设计?近期急需解决的几个突出问题是什么?上述诸多问题的探讨和解决,是地质勘查工作体制应对二十一世纪初国际新形势和满足我国全面建设小康社会提出的广泛社会需求,开创一个与国家发展水平相适应的、具有现代意义的地质勘查工作新局面的迫切要求。     

Trauma epidemiology in Puerto Rico: in-hospital morbidity and mortality from 2002 to 2011

This study aimed to describe the distribution of injury mechanisms and to assess the impact of those mechanisms on the morbidity and mortality of trauma. All patients admitted to Puerto Rico Trauma Hospital (2002–2011) for road-traffic collisions (RTCs, 5,371), gunshot wounds (GSWs, 2,946), falls (2,319), pedestrian accidents (1,652), and stab wounds (SWs, 1,073) were selected. Gunshot victims were 1.19 (95%CI: 1.07–1.33) times as likely as road-traffic victims to have an ISS ≥25. Pedestrians were 1.76 (95%CI: 1.49–2.09) times more likely to have a GCS ≤8 than road-traffic victims were. The risk of dying was 2.64 (95%CI: 2.20–3.16) times higher for gunshot victims and 1.51 (95%CI: 1.23–1.86) times higher for pedestrians compared to patients who had had RTCs. Gunshot victims and pedestrians had the worst clinical outcomes. Accordingly, these patients should receive the most aggressive clinical management. Furthermore, it is imperative to develop public health campaigns on trauma prevention.     

OPTIMAL CONTINUOUS-TIME HEDGING WITH LEPTOKURTIC RETURNS

We examine the behavior of optimal mean–variance hedging strategies at high rebalancing frequencies in a model where stock prices follow a discretely sampled exponential Lévy process and one hedges a European call option to maturity. Using elementary methods we show that all the attributes of a discretely rebalanced optimal hedge, i.e., the mean value, the hedge ratio, and the expected squared hedging error, converge pointwise in the state space as the rebalancing interval goes to zero. The limiting formulae represent 1-D and 2-D generalized Fourier transforms, which can be evaluated much faster than backward recursion schemes, with the same degree of accuracy. In the special case of a compound Poisson process we demonstrate that the convergence results hold true if instead of using an infinitely divisible distribution from the outset one models log returns by multinomial approximations thereof. This result represents an important extension of Cox, Ross, and Rubinstein to markets with leptokurtic returns.     

Knowledge embeddedness and the transfer mechanisms in multinational corporations

This paper reports a qualitative study conducted at four Japanese subsidiaries in China and Vietnam about their process of international knowledge transfer. Building on the literatures concerning the diverse types and characteristics of knowledge in multinational corporations (MNCs), we explore the broad mechanisms adopted and locally generated by the host country subsidiaries for transferring the foreign knowledge and putting the locally embedded knowledge into practical use at the local settings. The findings indicated (1) the limitations of applying a standardized and universal set of knowledge transfer mechanisms without considering local idiosyncrasies and (2) the contributions of local agents and institutions throughout the process of local knowledge adaptation and development.     

Spurious welfare reversals in international business cycle models

Several papers have documented spurious welfare reversals: incomplete-markets economy produces a higher level of welfare than the complete-markets economy. This paper first demonstrates how conventional linearization can generate approximation errors that can result in welfare reversals. Using a two-country production economy, we argue that spurious welfare reversals are not only possible but also plausible under reasonable values for model parameters. This paper then proposes an approximation method that modifies the conventional linearization by a bias correction. This method can be easily implemented and approximates welfare as accurately as a second-order perturbation method.     

沙棘叶多酚在苹果汁保鲜中的应用

沙棘叶多酚是从沙棘叶里提取出来的一种植物多酚,由于植物多酚的结构是多样性的,所以沙棘叶多酚具备多种生物活性。在沙棘叶多酚中具备一种较为特殊的活性,这就是抑菌活性。基于其抑菌活性的特点,人们可以将沙棘叶多酚应用于苹果汁保鲜中。由于沙棘叶多酚是一种天然的植物多酚,所以对人体并不会产生副作用,人们可以将其广泛地应用于苹果汁保鲜中。本文从沙棘叶多酚的提取、沙棘叶多酚的抑菌机制及在苹果汁保鲜中的应用等角度出发说明沙棘叶多酚在食品保鲜中的价值。