Optimal harvesting of a spatial renewable resource

In this paper we investigate the optimal harvesting of a renewable natural resource. While in most standard approaches the resource is located at a single point, we allow the resource to be distributed spatially. Consequently, an agent who exploits the resource has to travel from one location to another. For a fixed planning horizon, we investigate the speed and the path of harvesting chosen by the agent. We show that the agent adjusts this speed so as to visit each location only once, even in the absence of travelling cost. Since the agent does not return to any location for a second harvest, it is optimal to fully deplete the resource upon arrival. A similar type of bang–bang solution results when we drop the assumption of a constant harvesting rate: allowing for a variable harvesting rate, the agent chooses to fully exploit the resource either in the last or in the first travelling period. A society interested in conserving some of the resource thus has to take measures to limit the exploitative behaviour of the agent.     

The Load Model: an alternative to QALY

Background: QALYs are widely used in health economic evaluation, but remain controversial, largely because they do not reflect how many people behave in practice. This paper presents a new conceptual model (Load Model) and illustrates it in comparison with the QALY model.

Methods: Load is the average annual weight attributed to morbidity and mortality over a defined period, using weightings based on preference judgements. Morbidity Load is attributed to states of illness, according to their perceived severity. When people are in full health, Load is zero (no morbidity). Death is treated as an event with negative consequences, incurred in the year following death. Deaths may be weighted equally, with a fixed negative weight such as ?100, or differ according to the context of death. After death, Load is zero. In a worked example, we use the standard gamble method to obtain a weighting for an illness state, for both Load and QALY models. A judge is indifferent between certainty of 1.5 years’ illness followed by death, or a 50/50 chance of 1.5 years’ full health or 1-year illness, each followed by death. The weightings calculated are applied to a hypothetical life, 72 years in full health followed by 3 years with illness then death, using both models. Three other hypothetical outcomes are also compared.

Results: For an example life, the relative size of the morbidity component compared with the mortality component is much higher in the Load model than in the QALY model. When comparing alternative outcomes, there are also substantial differences between the two models.

Conclusions: In the Load model the weight of morbidity, relative to mortality, is very different from that in the QALY model. Given the role of the QALYs in economic evaluation, the implications of an alternative, which generates very different results, warrant further exploration.     

The trade-off between fixed vehicle costs and time-dependent arrival penalties in a routing problem

This paper introduces the vehicle routing problem with soft time windows (VRPSTW) in which problem definition differs from ones previously defined in literature. Branch-and-price approach is employed, resulting in a set partitioning master problem and its new subproblem. Novel techniques are consequently developed to solve this new subproblem. Experimental results report the comparisons of these solution techniques under the branch-and-price framework. The VRPSTW solutions have further been compared to the state-of-the-art literature, signifying the superiority of the VRPSTW on this issue.     

A new assessment of economic integration in East Asia: Application of an industry-specific G-PPP model

It is well known that intra-industry trade and cross-border production networks have promoted economic growth and regional integration in East Asia. However, regional supply and production chains may have been formed differently across industries, reflecting different degrees and a different scope of regional economic linkages at an industry level. This paper makes a threefold contribution. First, to assess industry-level differences, this study adopts the generalized purchasing power parity (G-PPP) model using industry-specific producer prices. Second, the momentum threshold autoregressive (M-TAR) model is employed to allow for possible nonlinearity arising from the dynamic nature of regional economic growth and development. Third, the Granger causality test is also conducted to assess whether regional economies have autonomously integrated. The empirical results reveal that economic integration has progressed more autonomously in the electrical industry, as well as in the transportation equipment industry, as China and the ASEAN countries have become the final destination markets for finished products in these two industries.     

SVHC第23批新增4项物质测试方法研究

本文建立了同时测定欧盟高关注物质(SVHC)第23批新增的4种物质[1-乙烯基咪唑、-甲基咪唑、4-羟基苯甲酸丁酯、双(乙酰丙酮酸)二丁基锡的气相色谱质谱联用仪(GC-MS)]的检测方法。将样品用二氯甲烷超声后,采用选择离子监控模式(SIM)进行分析样品中的待测物。实验结果表明,4种物质在50 mg/L范围内线性关系良好,线性相关系数为0.995以上;样品加标回收率为94%110%,相对标准偏差(RSD)小于7%;方法检出限分别为2 mg/kg、10mg/kg、0.8 mg/kg、0.6 mg/kg,解决了欧盟新增加的4种SVHC测试问题。     

Does boardroom nationality affect the performance of UK insurers?

Drawing on the board capital literature, we use a panel data design to investigate the effect of boardroom nationality on the profitability and solvency of property-casualty insurers operating in the United Kingdom (UK). We find that boardroom nationality influences corporate outcomes depending on the financial aspects being measured. For example, North American directors are linked with profitable outcomes, while European directors tend to be associated with better solvency. This reflects differences between the shareholder value corporate culture in North America and stakeholder approaches more common in Europe. Our results could help insurers, regulators, and others (e.g., investors) to better understand the potential performance implications of the appointment of directors of different nationality.     

In landscape management all of us have something to say. A holistic method for landscape Preservability evaluation in a Mediterranean region

Landscape assessment methods have traditionally valued the landscape through a panel of experts with little or no participation of the population. However, after the adoption of the European Landscape Convention (ELC), the perception and the participation of the population has played an increasingly important role in landscape evaluation and planning. In this regard, the goal of this paper is to develop a model able to evaluate and integrate both the objective and subjective landscape factors into a new concept: the Preservability. This model, as well as selecting and classifying the landscape attributes according to the bio-geographic features of the study area i.e., Ricote Valley (Region of Murcia, Spain), includes two online surveys: one to assess the populatiońs landscape preferences and the other to obtain the specific weight of each objective and subjective landscape factor from a panel of experts. These landscape factors were incorporated into a GIS. To obtain the best model, the Preservability was assessed from three different approaches: objective, objective-weighted and weighted. The final results demonstrate how the Preservability weighted method returns different thresholds appropriate to the landscape attributes, the population’s perceptual preference and the protected areas. The different thresholds allows for priority areas to be identified for protection, as well as the adoption of appropriate management and planning strategies according to the landscapes characteristics, current state and uniqueness.     

Ad hoc网络中基于多波束天线的集中式低时延调度算法

UxDMA算法是一种高效的集中式算法，是用于时分多址、频分多址和码分多址信道分配的统一算法。在UxDMA的基础上，利用多波束天线的多波束形成能力，针对低时延定向ad hoc网络提出了一种集中式调度算法——CLSM(Centralized Low-delay Scheduling Algorithm Based on Multi-beam Antennas)。CLSM通过不同时延等级限制的报文来比较着色后发送链路的优先级，优先选择高优先级链路传输。通过仿真验证了CLSM的性能：与UxDMA相比，该算法在多时延限制的发送端调度中表现出了更好的吞吐量和时延性能。     

Crowdfunding: The collaborative economy for channelling institutional and household savings

The financial disintermediation mechanism known as “loan-based-crowdfunding” has recently come under regulation in several countries. This competitive investment and finance vehicle is already well established in the US and British markets.By compiling empirical data from a reference crowdfunding platform, this article compares loan-based crowdfunding with traditional investment vehicles such as investment funds, equities or pension funds.The conclusion of the study is that saving through crowdfunding allows the optimization of a portfolio comprising both institutional and retail investors.     

Noisy signaling in discrete time

This paper characterizes the equilibrium set of a dynamic noisy-signaling model in discrete time. A seller privately knows the quality of her asset. She can exert a costly effort to generate stochastic returns. Buyers stochastically arrive over time and, after observing the history of returns, they make price offers. In our model, the equilibrium behavior of the buyers is discontinuous: they only make acceptable (high) offers if the posterior about the quality is above a given threshold. As a result, the recursive nature of the model replicates the discontinuity, giving the equilibrium continuation payoff a complex self-replicating structure that may take the form of a devil’s staircase.