Using In Vitro High‐Throughput Screening Data for Predicting Benzo[k]Fluoranthene Human Health Hazards

Today there are more than 80,000 chemicals in commerce and the environment. The potential human health risks are unknown for the vast majority of these chemicals as they lack human health risk assessments, toxicity reference values, and risk screening values. We aim to use computational toxicology and quantitative high‐throughput screening (qHTS) technologies to fill these data gaps, and begin to prioritize these chemicals for additional assessment. In this pilot, we demonstrate how we were able to identify that benzo[k]fluoranthene may induce DNA damage and steatosis using qHTS data and two separate adverse outcome pathways (AOPs). We also demonstrate how bootstrap natural spline‐based meta‐regression can be used to integrate data across multiple assay replicates to generate a concentration–response curve. We used this analysis to calculate an in vitro point of departure of 0.751 μM and risk‐specific in vitro concentrations of 0.29 μM and 0.28 μM for 1:1,000 and 1:10,000 risk, respectively, for DNA damage. Based on the available evidence, and considering that only a single HSD17B4 assay is available, we have low overall confidence in the steatosis hazard identification. This case study suggests that coupling qHTS assays with AOPs and ontologies will facilitate hazard identification. Combining this with quantitative evidence integration methods, such as bootstrap meta‐regression, may allow risk assessors to identify points of departure and risk‐specific internal/in vitro concentrations. These results are sufficient to prioritize the chemicals; however, in the longer term we will need to estimate external doses for risk screening purposes, such as through margin of exposure methods.     

金融资产的动态非线性相关:一个新的模型

基于Kendall’sτ秩相关系数的优越性和定义,本文提出了新的具有明确经济意义的动态条件相关copula模型,将常用的Gaussian、Clayton和Gumbel函数统一根据该演化方程实现动态化,构造出三种Kendall’sτ动态条件相关copula模型,可用于刻画不同的相关模式。这些模型不仅参数少、容易估计,避免了现有动态条件相关copula模型构建方法各异导致的在实证中不利于比较的缺点,而且能够进行多步向前预测,有效地减少了进行样本外预测时的计算量,从而为刻画时变、非线性、非对称性和尾部相关等复杂的动态相关模式提供了新方法。     

Optimal financing and dividend policy with Markovian switching regimes

This work investigates an optimal financing and dividend problem for an insurer whose surplus process is modulated by an observable continuous-time and finite-state Markov chain. We assume that the insurer should never go bankrupt by issuing new equity. The goal of the insurer is to maximize the expected present value of the dividends payout minus the discounted cost of equity issuance. We obtain the optimal policies and explicit expressions for the value functions when the risk reserve process is modeled by both upward jump model and its diffusion approximation. Numerical illustrations of the sensitivities of the model parameters are provided.     

低压及欠平衡钻井中注气量对井内压力的影响

以多相瞬变流理论为基础,建立了井筒内气液两相流动模型,并对低压欠平衡钻井中注气量对井内压力的影响关系和规律进行计算和分析。计算分析结果表明,注气量对井内压力的影响除与注气量本身大小有关外,还与井深、井眼与钻柱结构尺寸、井内液相流量和性质等因素密切相关。单纯增大注气量并不一定就必然会导致井内压力的降低,这取决于所给条件下构成井筒内气液两相流体的静液压力和流阻间的平衡关系。介绍的模型及方法对确定低压欠平衡钻井过程中各相关参数、地面压缩机组的配置、以及设计方案等有一定指导意义。     

Adaptation of the jackknifed ridge methods to the linear mixed models

The purpose of this article is to obtain the jackknifed ridge predictors in the linear mixed models and to examine the superiorities, the linear combinations of the jackknifed ridge predictors over the ridge, principal components regression, r?k class and Henderson's predictors in terms of bias, covariance matrix and mean square error criteria. Numerical analyses are considered to illustrate the findings and a simulation study is conducted to see the performance of the jackknifed ridge predictors.     

Odd-Burr generalized family of distributions with some applications

We study a new family of continuous distributions with two extra shape parameters called the Burr generalized family of distributions. We investigate the shapes of the density and hazard rate function. We derive explicit expressions for some of its mathematical quantities. The estimation of the model parameters is performed by maximum likelihood. We prove the flexibility of the new family by means of applications to two real data sets. Furthermore, we propose a new extended regression model based on the logarithm of the Burr generalized distribution. This model can be very useful to the analysis of real data and provide more realistic fits than other special regression models.     

Constructing ‘disability’ in Myanmar: teachers,community stakeholders,and the complexity of disability models

This article explores Myanmar teachers’ and community stakeholders’ constructions of disability. We examine how various religious perspectives – particularly Buddhism – inform and shape understandings of impairment and how these beliefs intersect with a strongly medicalised construction of disability. However, in our discussion and exploration of the responses, we also found that the notion of two primary disability ‘models’ – namely the medical model and the social model – lack nuance, complexity, and socio-cultural consideration. Through examining teachers’ and community members’ perspectives of disability in Myanmar, we highlight the importance of socio-cultural variance in understanding local constructions of disability.     

Dealing with context in logic model development: Reflections from a realist evaluation of a community health worker programme in Nigeria

Logic models (LMs) have been used in programme evaluation for over four decades. Current debate questions the ability of logic modelling techniques to incorporate contextual factors into logic models. We share experience of developing a logic model within an ongoing realist evaluation which assesses the extent to which, and under what circumstances a community health workers (CHW) programme promotes access to maternity services in Nigeria. The article contributes to logic modelling debate by: i) reflecting on how other scholars captured context during LM development in theory-driven evaluations; and ii) explaining how we explored context during logic model development for realist evaluation of the CHW programme in Nigeria. Data collection methods that informed our logic model development included documents review, email discussions and teleconferences with programme stakeholders and a technical workshop with researchers to clarify programme goals and untangle relationships among programme elements. One of the most important findings is that, rather than being an end in itself, logic model development is an essential step for identifying initial hypotheses for tentative relevant contexts, mechanisms and outcomes (CMOs) and CMO configurations of how programmes produce change. The logic model also informed development of a methodology handbook that is guiding verification and consolidation of underlying programme theories.     

节目试看对网络视频运营商市场策略影响研究

随着网络视频运营商收费节目试看的兴起，而节目试看对网络视频运营商诸如市场规模，利润等市场策略的影响所知甚少。本文在考虑网络用户情绪效用情况下，通过构建高质量视频运营商首播节目与后来跟进的低质量视频运营商播出该节目的博弈模型，研究高质量视频运营商首播节目之前提供节目试看对两个运营商收费模式下的节目最优收费价格和免费模式下的最优嵌入广告量以及视频节目提供模式选择的影响。研究表明，高质量视频运营商在节目首播之前提供节目充分试看能够实现节目最优收费价格最高，利润最大，因此节目充分试看是其最优策略；并且低质量运营商在其单位广告收益与用户单位广告"成本"满足一定条件下，高质量运营商提供的节目的充分试看能够减少低质量运营商总利润，因此避免低质量视频运营商搭乘节目试看的顺风车；高质量视频运营商提供节目充分试看情况下，高质量视频运营商只采取收费模式为其最优市场策略，低质量视频运营商采取免费模式为其最优市场策略。本文的研究成果对网络视频运营商日常运营有一定的管理学启示与应用价值。     

大芦家地区东二1亚段砂体微相纵横向分布研究

大芦家地区渐新统东二1亚段主要由三角洲前缘亚相组成,发育的微相类型包括河口坝、水下分流河道、水下决口扇及天然堤、远砂坝、席状砂、分流间湾等,它们在纵横向上表现出多次复合,多次叠加的特征,且各微相的界限和单砂层的界限并不一致;所有这些微相在垂向上的沉积序列可分为均一型、垂向减小型和垂向增大型三类;此外,该区三角洲体系沉积物源主要由河流从西北方向搬运而来,属高建设性的河控型三角洲,其平面呈朵状向东南方或南方延伸,其微相模式的特点是水下分流河道和河口坝沉积位于中心,其他微相分布在它们的外缘。