An approach to the nonlinear dynamics of Russian wheat aphid population growth with the cusp catastrophe model

Many insect field populations, especially aphids, often exhibit irregular and even catastrophic fluctuations. The objective of the present study is to explore whether or not the population intrinsic rates of growth ( r _m) obtained under laboratory conditions can shed some light on the irregular changes of insect field populations. We propose to use the catastrophe theory, one of the earliest nonlinear dynamics theories, to answer the question. To collect the necessary data, we conducted a laboratory experiment to investigate population growth of the Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), in growth chambers. The experiment was designed as the factorial combinations of five temperatures and five host plant-growth stages (25 treatments in total): 1800 newly born RWA nymphs arranged in the 25 treatments (each treatment with 72 repetitions) were observed for their development, reproduction and survival through their entire lifetimes. After obtaining the population intrinsic rates of growth ( r _m) from the experimental data under various environmental conditions, we built a cusp catastrophe model for RWA population growth by utilizing r _m as the system state variable, and temperature and host plant-growth stage as control variables. The cusp catastrophe model suggests that RWA population growth is intrinsically catastrophic , and dramatic jumps from one state to another might occur even if the temperature and plant-growth stage change smoothly . Other basic behaviors of the cusp catastrophe model, such as catastrophic jumps , hystersis and divergence , are also expected in RWA populations. These results suggest that the answer to the previously proposed question should be "yes".     

害虫种群动态模型的燕尾突变分析

在农田生态系统中,以作物状况、气象因素及天敌分别为3种控制变量,以害虫种群数量动态为状态变量,建立了燕尾突变模型,并用燕尾突变模型的性质分析害虫种群数量动态中产生的突变现象.具体对燕尾突变的分歧点集所分各个控制区域的系统势函数形式和平衡点情况进行了分析,说明了害虫种群数量发生突变的条件和机理,为实际应用提供理论依据.同时利用燕尾突变的性质直观描述了害虫种群数量变化中的突跳和滞后等现象.     

Health-Related Financial Catastrophe,Inequality and Chronic Illness in Bangladesh

Background

Bangladesh has a high proportion of households incurring catastrophic health expenditure, and very limited risk sharing mechanisms. Identifying determinants of out-of-pocket (OOP) payments and catastrophic health expenditure may reveal opportunities to reduce costs and protect households from financial risk.

Objective

This study investigates the determinants of high healthcare expenditure and healthcare- related financial catastrophe.

Methods

A cross-sectional household survey was conducted in Rajshahi city, Bangladesh, in 2011. Catastrophic health expenditure was estimated separately based on capacity to pay and proportion of non-food expenditure. Determinants of OOP payments and financial catastrophe were estimated using double hurdle and Poisson regression models respectively.

Results

On average households spent 11% of their total budgets on health, half the residents spent 7% of the monthly per capita consumption expenditure for one illness, and nearly 9% of households faced financial catastrophe. The poorest households spent less on health but had a four times higher risk of catastrophe than the richest households. The risk of financial catastrophe and the level of OOP payments were higher for users of inpatient, outpatient public and private facilities respectively compared to using self-medication or traditional healers. Other determinants of OOP payments and catastrophic expenses were economic status, presence of chronic illness in the household, and illness among children and adults.

Conclusion

Households that received inpatient or outpatient private care experienced the highest burden of health expenditure. The poorest members of the community also face large, often catastrophic expenses. Chronic illness management is crucial to reducing the total burden of disease in a household and its associated increased risk of level of OOP payments and catastrophic expenses. Households can only be protected from these situations by reducing the health system''s dependency on OOP payments and providing more financial risk protection.     

Earthquake Insurance and Earthquake Risk Management

The Wenchuan earthquake is the largest devastating earthquake striking China since the 1976 Tangshan earthquake. In this catastrophe, loss payments were mainly from the government and public endowment. The insurance industry is expected to take more responsibility in the future, since earthquake insurance is one of the most effective and equitable instruments to disperse earthquake losses. In this article, earthquake risk management and the development of earthquake insurance in China are reviewed. Earthquake insurance is suggested as an instrument in earthquake risk management, where the premium rate of earthquake insurance is a key factor that needs to be determined reasonably. Seismic hazard is analyzed for the Wenchuan earthquake-stricken area, and is combined with primary loss estimation to construct the exceeding probability curve. Earthquake insurance premium rates are calculated for buildings in the area, including RC (Reinforced Concrete), frame, and brick, corresponding to two kinds of insurance deductible.     

Microtubule dynamic instability: A new model with coupled GTP hydrolysis and multistep catastrophe

A key question in understanding microtubule dynamics is how GTP hydrolysis leads to catastrophe, the switch from slow growth to rapid shrinkage. We first provide a review of the experimental and modeling literature, and then present a new model of microtubule dynamics. We demonstrate that vectorial, random, and coupled hydrolysis mechanisms are not consistent with the dependence of catastrophe on tubulin concentration and show that, although single‐protofilament models can explain many features of dynamics, they do not describe catastrophe as a multistep process. Finally, we present a new combined (coupled plus random hydrolysis) multiple‐protofilament model that is a simple, analytically solvable generalization of a single‐protofilament model. This model accounts for the observed lifetimes of growing microtubules, the delay to catastrophe following dilution and describes catastrophe as a multistep process.     

Using site assessment and risk analysis to plan and build disaster-resistant programs and facilities

Research animals need protection from the catastrophic losses that can occur during disasters. The best method of protecting animals is to house them in facilities that have been reinforced using disaster-resistant construction methods. The authors explain the use of site-specific risk analysis to determine the proper building site and features.     

突变级数法在厦门城市生态安全评价中的应用

针对港湾快速城市化地区存在的潜在突变特性,基于P-S-R(压力-状态-响应)框架和突变级数法,构建了评价城市生态安全的突变模型,并对1996—2006年厦门城市生态安全进行了评价.结果表明：1996—1998年,快速城市化对厦门市区域生态安全的影响不大,研究区生态安全状况呈上升趋势;1998—2001年,由于大范围高强度的填海造地、人口激增等生态干扰远远超过了生态系统自身的修复能力,导致厦门城市生态安全状况呈快速下降趋势;2001—2006年,厦门城市生态安全整体水平回升,主要受其海湾型生态城市重大战略转变的影响;2006年,研究区系统压力安全级别为Ⅲ,说明厦门市还存在着生态安全隐患.突变级数法反映了单一指标极值情况对生态系统突变的影响,弥补了现有方法在此方面的不足,它既减小了权重赋值的主观性,又避免了主观判断安全标准的不确定性,可准确地反映城市生态安全的发展趋势.     

Americanist Archaeologies: 2008 in Review

ABSTRACT   A review of published literature, conference proceedings, and Internet sources pertaining to "Americanist archaeology" in 2008 reveals three major themes: conflict, catastrophe, and collaboration. Scholars debated the role of archaeology in planning for and executing military operations in the Middle East while maintaining a vigorous interest in structural and physical violence worldwide. Environmental archaeologists considered the effects of catastrophic events, including new theories over the demise of Clovis cultures. In addition, several major reports and regulations highlighted the complexities of indigenous relations and gender equity in the profession. Enhanced technologies, funding for global initiatives in human rights, economic and environmental sustainablility, and creative forms of engagement are reshaping "Americanist archaeology" as a democratic, anthropological, and relevant pursuit. [Keywords: archaeology, annual review, conflict, catastrophe, collaboration]     

Catastrophe Risk Analysis: A Financial Perspective

This article examines how catastrophe events affect risk analysis from a financial perspective. Data from different industries such as Advanced Sustainable Performance Indices, gold, energy, real estate, and insurance were collected and analyzed. The performance of these funds was compared by using various financial ratios. Then we tested the stock selecting and market timing abilities. We also assessed whether a particular catastrophe event has affected stock prices by analysis of two event studies, the 9/11 terrorist attacks in the United States and the collapse through bankruptcy of Lehman Brothers. We examined how an asset portfolio performs under catastrophic events and under the situation of adding Advanced Sustainable Performance Indices into an investor's portfolio basket. We found that the 9/11 terrorist attacks affected the Dow Jones Real Estate Index's prices a lot. Lehman Brothers' bankruptcy filing had a positive impact on the CBOE Gold Index, and had a large impact on the Fidelity US Bond Index. The ASPI Index in our optimization problem gave us better diversification. From our analysis, we conclude that portfolio diversification is a good way to hedge against catastrophic risk.     

Catastrophic Collapse Can Occur without Early Warning: Examples of Silent Catastrophes in Structured Ecological Models

Catastrophic and sudden collapses of ecosystems are sometimes preceded by early warning signals that potentially could be used to predict and prevent a forthcoming catastrophe. Universality of these early warning signals has been proposed, but no formal proof has been provided. Here, we show that in relatively simple ecological models the most commonly used early warning signals for a catastrophic collapse can be silent. We underpin the mathematical reason for this phenomenon, which involves the direction of the eigenvectors of the system. Our results demonstrate that claims on the universality of early warning signals are not correct, and that catastrophic collapses can occur without prior warning. In order to correctly predict a collapse and determine whether early warning signals precede the collapse, detailed knowledge of the mathematical structure of the approaching bifurcation is necessary. Unfortunately, such knowledge is often only obtained after the collapse has already occurred.     

Fifty millennia of catastrophic extinctions after human contact

Debate continues to rage between enthusiasts for climate change versus humans as a cause of the catastrophic faunal extinctions that have occurred in the wake of human arrival in previously uninhabited regions of the world. A global pattern of human arrival to such landmasses, followed by faunal collapse and other ecological changes, appears without known exception. This strongly suggests to some investigators that a more interesting extinction debate lies within the realm of potential human-caused explanations and how climate might exacerbate human impacts. New observations emerging from refined dating techniques, paleoecology and modeling suggest that the megafaunal collapses of the Americas and Australia, as well as most prehistoric island biotic losses, trace to a variety of human impacts, including rapid overharvesting, biological invasions, habitat transformation and disease.     

Chromosome catastrophes involve replication mechanisms generating complex genomic rearrangements

Complex genomic rearrangements (CGRs) consisting of two or more breakpoint junctions have been observed in genomic disorders. Recently, a chromosome catastrophe phenomenon termed chromothripsis, in which numerous genomic rearrangements are apparently acquired in one single catastrophic event, was described in multiple cancers. Here, we show that constitutionally acquired CGRs share similarities with cancer chromothripsis. In the 17 CGR cases investigated, we observed localization and multiple copy number changes including deletions, duplications, and/or triplications, as well as extensive translocations and inversions. Genomic rearrangements involved varied in size and complexities; in one case, array comparative genomic hybridization revealed 18 copy number changes. Breakpoint sequencing identified characteristic features, including small templated insertions at breakpoints and microhomology at breakpoint junctions, which have been attributed to replicative processes. The resemblance between CGR and chromothripsis suggests similar mechanistic underpinnings. Such chromosome catastrophic events appear to reflect basic DNA metabolism operative throughout an organism's life cycle.     

Marlo’s windows: why it is a mistake to ignore hazard resistance in LCA

Purpose

Hazard-resistant materials for homes promise environmental benefits, such as avoided waste and materials for repairs, which can be overlooked by scoping in life-cycle assessment (LCA) approaches. Our motivation for pursuing this research was to see how incorporating these avoided losses in the LCA could impact choices between hazard-resistant and traditional materials.

Methods

Two choices common in home construction were analyzed using an LCA process that incorporates catastrophe modeling to consider avoided losses made possible with hazard-resistant materials. These findings were compared to those based on a similar LCA that did not consider these avoided losses. The choices considered were standard windows vs. windows with impact-resistant glass and standard windows with no opening protection vs. standard windows with impact-resistant storm panels.

Results and discussion

For the window comparisons, the standard products were environmentally preferable when avoided losses from storm events were not considered in the LCA. However, when avoided losses were considered, the hazard-resistant products were environmentally preferable. Considering avoided losses in LCAs, as illustrated by the window choices, can change which product appears to be the environmentally preferable option. Further, as home service life increases, the environmental net benefit of the hazard-resistant product increases.

Conclusions

Our results show the value of an LCA approach which allows more complete scopings of comparisons between hazard-resistant materials and their traditional counterparts. This approach will help translate the impacts of hazard-resistant products into the more familiar language used to talk about “green” products, enabling more informed decisions by product manufacturers, those who develop building certification systems and codes, researchers, and other building industry stakeholders.     

The Evolution of Strategic Timing in Collective-Risk Dilemmas

In collective-risk dilemmas, a group needs to collaborate over time to avoid a catastrophic event. This gives rise to a coordination game with many equilibria, including equilibria where no one contributes, and thus no measures against the catastrophe are taken. In this game, the timing of contributions becomes a strategic variable that allows individuals to interact and influence one another. Herein, we use evolutionary game theory to study the impact of strategic timing on equilibrium selection. Depending on the risk of catastrophe, we identify three characteristic regimes. For low risks, defection is the only equilibrium, whereas high risks promote equilibria with sufficient contributions. Intermediate risks pose the biggest challenge for cooperation. In this risk regime, the option to interact over time is critical; if individuals can contribute over several rounds, then the group has a higher chance to succeed, and the expected welfare increases. This positive effect of timing is of particular importance in larger groups, where successful coordination becomes increasingly difficult.     

生态系统状态跃变的早期预警信号及检测

生态系统在气候变化和土地利用及人类活动等的影响下其状态会由某一稳态转变到另一稳态。由于环境压力的复杂性、非线性、随机性等特征，往往导致状态转变表现为非线性、突变、跃变等特点。准确界定系统状态跃变的拐点或阈值点存在很大的挑战，而捕捉接近临界拐点前的生态系统结构和属性上的变化特征作为早期预警信号是切实可行的。早期预警信号理论经历理论框架构建、方法确立、机理认知等近半个多世纪的探索，已经由最初的通过仅依赖检测临界点恢复力的速率减慢、方差增加、系统自相关增强等统计学信号过度到更加多样化的检测方法，如检测系统组分属性的变化特征，诊断系统组分各属性之间的关系变化，系统组分的性状变化、系统组分网络结构变化等等，并且试图整合多信号提高预警的精确性。利用来自自然生态系统的长时间高密度数据集和空间代替时间的数据集，基于多度及性状信号的早期预警，结合稳定性、临界恢复力的减速、以及统计参数的指示作用对系统跃变进行早期诊断和预警是预测生态学的主旨。早期预警信号的深入研究不仅能够完善已有理论的不足，同时还能够为生态系统的保护和管理提供切实有效的理论指导。     

Perspectives and mechanisms for targeting mitotic catastrophe in cancer treatment

Mitotic catastrophe is distinct from other cell death modes due to unique nuclear alterations characterized as multi and/or micronucleation. Mitotic catastrophe is a common and virtually unavoidable consequence during cancer therapy. However, a comprehensive understanding of mitotic catastrophe remains lacking. Herein, we summarize the anticancer drugs that induce mitotic catastrophe, including microtubule-targeting agents, spindle assembly checkpoint kinase inhibitors, DNA damage agents and DNA damage response inhibitors. Based on the relationships between mitotic catastrophe and other cell death modes, we thoroughly evaluated the roles played by mitotic catastrophe in cancer treatment as well as its advantages and disadvantages. Some strategies for overcoming its shortcomings while fully utilizing its advantages are summarized and proposed in this review. We also review how mitotic catastrophe regulates cancer immunotherapy. These summarized findings suggest that the induction of mitotic catastrophe can serve as a promising new therapeutic approach for overcoming apoptosis resistance and strengthening cancer immunotherapy.     

On a global representation of dynamical characteristics in ESS-models

ESS-models are considered in the frame of adequate dynamical systems. This leads to a method of global representation of the dynamical characteristics, which allows for a comprehensive view on the relations among ESS-matrices. As an extension of ESS-models, the concept of ESS-models with changing matrix is introduced, which, in applications, makes use of such global representations. In particular, structurally stable and “catastrophic” cases can be identified and their significance in the context of ESS-models can be clarified. As a complete result for the case of two strategies a surface representation is obtained, which is an analogue to the elementary “cusp catastrophe”. These concepts are applied in a model that describes directed evolution of a behavioural component to a certain limit.     

An environmental study of Silurian atrypid communities from southern Norway

Atrypid communities are described from the Silurian succession of southern Norway. These atrypids show striking variation in their mode of occurrence, several features of which are described quantitatively. Mature, well-developed communities occur in calcareous rocks which were apparently deposited in a well-aerated shallow environment. Stunted communities (identified by small shell size despite maturity) occur in carbonate-poor sediments deposited in deeper and less turbulent environments. Other communities are composed of immature shells which were apparently killed by a catastrophic event. Communities are also seen in which catastrophe was not total, and survivors can be recognised. The atrypid niche was taken over by other animal communities when major environmental changes took place.