Improved Transferability of Data‐Driven Damage Models Through Sample Selection Bias Correction

Damage models for natural hazards are used for decision making on reducing and transferring risk. The damage estimates from these models depend on many variables and their complex sometimes nonlinear relationships with the damage. In recent years, data‐driven modeling techniques have been used to capture those relationships. The available data to build such models are often limited. Therefore, in practice it is usually necessary to transfer models to a different context. In this article, we show that this implies the samples used to build the model are often not fully representative for the situation where they need to be applied on, which leads to a “sample selection bias.” In this article, we enhance data‐driven damage models by applying methods, not previously applied to damage modeling, to correct for this bias before the machine learning (ML) models are trained. We demonstrate this with case studies on flooding in Europe, and typhoon wind damage in the Philippines. Two sample selection bias correction methods from the ML literature are applied and one of these methods is also adjusted to our problem. These three methods are combined with stochastic generation of synthetic damage data. We demonstrate that for both case studies, the sample selection bias correction techniques reduce model errors, especially for the mean bias error this reduction can be larger than 30%. The novel combination with stochastic data generation seems to enhance these techniques. This shows that sample selection bias correction methods are beneficial for damage model transfer.     

基于债务协商视角的债转股定量研究

针对我国政府、企业和银行等金融机构共同关注的债转股问题，基于债务协商谈判思想，建立部分债务股权互换模型，计算公司证券价格，探讨了债转股对公司价值、破产概率、破产损失成本和资本结构的影响，给出了银行等债权人愿意债转股的充分条件。结果表明：在事先破产清算协议贷款下，事后全部债转股总能提高公司股权价值，但并不一定能提高债券价值。只有其协商谈判能力满足一定条件，公司债权人才愿意事后选择债转股，实现帕累托改进、提高社会福利水平。其次，在公司股东协商谈判能力的一定范围内，部分债转股能提高公司价值，其最优转股债息比例随着公司资产风险的增大而增加。再次，债转股能降低公司破产风险和破产损失成本，但同时也提高了债券风险溢价。最后，随着股东谈判能力增强，最优协商转股债务比例、杠杆率都减少，而债券风险溢价增大。本文所得结果对我国政府、企业和银行如何实施债转股提供理论参考和实践指导。     

Fiddling while the planet burns? COP25 in perspective

ABSTRACT

With fires, storms, social protests, and climate strikes sweeping the world, 2019 should have been a tipping point in how the world responds to global heating. This was the backdrop to the COP25 climate change summit which took place in Madrid in December 2019. This paper assesses the outcomes of the meeting and the path towards the critically important meeting in Glasgow at the end of 2020. It analyses and explains the key points of contention over levels of ambition, the rules which should govern global carbon markets and sensitive issues such as loss and damage associated with the impacts of climate change. The analysis is situated within a broader geopolitical and economic context of right-wing populism, deepening forms of marketization and financialization of responses to climate change and against a background of a world increasingly feeling the effects of the climate crisis.     

Human Error in Autonomous Underwater Vehicle Deployment: A System Dynamics Approach

The use of autonomous underwater vehicles (AUVs) for various applications have grown with maturing technology and improved accessibility. The deployment of AUVs for under-ice marine science research in the Antarctic is one such example. However, a higher risk of AUV loss is present during such endeavors due to the extremities in the Antarctic. A thorough analysis of risks is therefore crucial for formulating effective risk control policies and achieving a lower risk of loss. Existing risk analysis approaches focused predominantly on the technical aspects, as well as identifying static cause and effect relationships in the chain of events leading to AUV loss. Comparatively, the complex interrelationships between risk variables and other aspects of risk such as human errors have received much lesser attention. In this article, a systems-based risk analysis framework facilitated by system dynamics methodology is proposed to overcome existing shortfalls. To demonstrate usefulness of the framework, it is applied on an actual AUV program to examine the occurrence of human error during Antarctic deployment. Simulation of the resultant risk model showed an overall decline in human error incident rate with the increase in experience of the AUV team. Scenario analysis based on the example provided policy recommendations in areas of training, practice runs, recruitment policy, and setting of risk tolerance level. The proposed risk analysis framework is pragmatically useful for risk analysis of future AUV programs to ensure the sustainability of operations, facilitating both better control and monitoring of risk.     

Comparing Possibly Misspecified Forecasts

Abstract

Recent work has emphasized the importance of evaluating estimates of a statistical functional (such as a conditional mean, quantile, or distribution) using a loss function that is consistent for the functional of interest, of which there is an infinite number. If forecasters all use correctly specified models free from estimation error, and if the information sets of competing forecasters are nested, then the ranking induced by a single consistent loss function is sufficient for the ranking by any consistent loss function. This article shows, via analytical results and realistic simulation-based analyses, that the presence of misspecified models, parameter estimation error, or nonnested information sets, leads generally to sensitivity to the choice of (consistent) loss function. Thus, rather than merely specifying the target functional, which narrows the set of relevant loss functions only to the class of loss functions consistent for that functional, forecast consumers or survey designers should specify the single specific loss function that will be used to evaluate forecasts. An application to survey forecasts of U.S. inflation illustrates the results.     

Development of an innovative process evaluation approach for the Families Improving Together (FIT) for weight loss trial in African American adolescents

This study demonstrates how a multi-theoretical, multilevel process evaluation was used to assess implementation of the Families Improving Together (FIT) for weight loss intervention. FIT is a randomized controlled trial evaluating a culturally tailored, motivational plus family-based program on weight loss in African American adolescents and their parents. Social Cognitive, Self Determination, Family Systems theories and cultural tailoring principles guided the conceptualization of essential elements across individual/family, facilitator, and group levels. Data collection included an observational rating tool, attendance records, and a validated psychosocial measure.ResultsAttendance records (0 = absent, 1 = present, criteria = ≥70%) indicated that 71.5% of families attended each session. The survey (1 = false, 6 = true, criteria = ≥4.5) indicated that participants perceived a positive group climate (M = 5.16, SD = 0.69). A trained evaluator reported that facilitator dose delivered (0 = no, 1 = yes, criteria = ≥75%) was high (99.6%), and fidelity (1 = none to 4 = all, criteria = ≥3) was adequate at facilitator (M = 3.63, SD = 0.41) and group levels (M = 3.35, SD = 0.49). Five cultural topics were raised by participants related to eating (n = 3) and physical activity (n = 2) behaviors and were integrated as part of the final curriculum.DiscussionResults identify areas for program improvement related to delivery of multi-theoretical and cultural tailoring elements. Findings may inform future strategies for implementing effective weight loss programs for ethnic minority families.     

泌阳凹陷泌301 井区不同流动单元产能分析

在沉积微相、储层物性特征分析的基础上，选取孔隙度、渗透率、流动带指数等参数，对泌阳凹陷赵凹油田泌301 井区核三段油层组进行流动单元划分。依据流动带指数的大小，将研究区目的层段划分为A、B、C、D 和E 等5 类流动单元。通过研究发现，各类流动单元与物性、岩性、沉积微相之间具有较好的对应关系，同时对不同流动单元产能进行了分析。研究结果表明，流动单元的划分能够真实客观地反映储层物性差、非均质性强的地质特点，单井产能与流动带指数有较好的乘幂关系，不同流动单元产能差异较为明显，物性最好的A 类流动单元产能最高，物性最差的E类流动单元产能最低。     

陆梁油田薄层底水油藏水平井井筒模拟研究

新疆陆梁油田呼图壁河组油藏发育一类特殊的薄层底水型油藏，其特点是油层厚度薄，构造幅度低，底水能量大，利用水平井开采，表现出无水采油期短、含水率上升速度快、产量递减大的特点。针对这些问题，采用水平井数值模拟方法，建立了考虑摩擦压力损失的水平井井筒模型，明确了摩擦压力损失对水平井的压力分布以及水平段产量的影响，在此基础上，分析研究了水平井底水锥进的水脊特征，判断了水平井出水位置，提出了封堵出水井段并结合油藏工程方法确定了水平井合理产液量，从而达到抑制底水快速锥进，减小压力损失，降低含水率上升速度的目的。     

Loss and grief: The experience of transition to residential aged care

There is growing recognition of the experience of non-death-related loss and grief. One unexplored area of non-death-related loss and grief is associated with older people’s transition from home to residential aged care (RAC). This paper reports findings from a qualitative study that explored the experiences of people living in RAC, carer-relatives of people living in RAC and RAC staff. Using theories of loss and grief, the paper identifies features of the transition to RAC that are associated with unresolved loss and maladaptation to changed circumstances, and the types of support that would mitigate these. Using a series of focus groups with both residents and carer-relatives, as well as staff, the study found that residents and their families need more support to negotiate the multiple, often necessarily hasty decisions and bureaucratic requirements associated with transitioning to RAC, while simultaneously experiencing loss and grief. The types of support that families would welcome from service providers include facilitating shared decision making, valuing family and community carer expertise and providing practical information and assistance to fulfil administrative obligations.     

Pregnancy after loss during the COVID19 pandemic

BackgroundRapid changes to how maternity health care is delivered has occurred in many countries across the globe in response to the COVID-19 pandemic. Maternity care provisions have been challenged attempting to balance the needs and safety of pregnant women and their care providers. Women experiencing a pregnancy after loss (PAL) during these times face particularly difficult circumstances.AimIn this paper we highlight the situation in three high income countries (Australia, Ireland and USA) and point to the need to remember the unique and challenging circumstances of these PAL families. We suggest new practices may be deviating from established evidence-based guidelines and outline the potential ramifications of these changes.FindingsRecommendations for health care providers are suggested to bridge the gap between the necessary safety requirements due to the pandemic, the role of the health care provider, and the needs of families experiencing a pregnancy after loss.DiscussionChanges to practices i.e. limiting the number of antenatal appointments and access to a support person may have detrimental effects on both mother, baby, and their family. However, new guidelines in maternity care practices developed to account for the pandemic have not necessarily considered women experiencing pregnancy after loss.ConclusionBereaved mothers and their families experiencing a pregnancy after loss should continue to be supported during the COVID-19 pandemic to limit unintended consequences.