bluuebunny/crossref_metadata_2025 huggingface dataset:
An optical system with aberrations on diffraction integrals written in terms of a generalized ABCD matrix
Authors: Zhao Chaoying , Tan Weihan
Published: September 2008

Abstract: In this paper, we consider the transformation of a ray beam as it passes through an optical system containing a glass plate with parallel surfaces inclined to the optical axis at the Brewster’s angle, by investigating the effects of the optical system on amplitude and phase distributions. By applying generalized matrix optics and diffraction integrals and considering the influence of a quarter of a wavelength of aberration on the transmitted amplitude and phase distributions at the focus of a de-collimating lens, we find that the central peak amplitude descends from 1.0 to 0.8 and the phase distortion is less than π/2. The general feature of the amplitude distribution shows an elongation along the y-axis perpendicular to the optical axis in the direction of tilt of the inclined plate, and conforms to the inclination direction of the glass plate.
Experimental demonstration of singular-optical colouring of regularly scattered white light
Authors: Angelsky O. V. , Hanson S. G. , Maksimyak P. P. , Maksimyak A. P. , Negrych A. L.
Published: September 2008

Experimental interference modelling of the effects of colouring of a beam traversing a light-scattering medium is presented. It is shown that the result of colouring of the beam at the output of the medium depends on the magnitudes of the phase delays of the singly forward scattered partial signals. The colouring mechanism has for the first time experimentally been illustrated for a forward propagating beam through a light-scattering medium. This is showed in video-fragments of the interferograms recorded within the zero interference fringe with a gradual change of the path difference of the interfering polychromatic wave trains. Spectral investigation of the effects of colouring has been carried out using a solution of liquid crystal in a polymer matrix. The amplitude ratio of the non-scattered and the singly forward scattered interfering components significantly affects the colour intensity. It has further been established that the spectral content of the illuminating beam strongly influences the colour of the resulting radiation.
Statistical classification of terrestrial and marine ecosystems for environmental planning
Authors: Schröder Winfried , Pesch Roland , Schmidt Günther
Published: September 2008

Environmental planning is an instrument for the operationalisation of the precautionary principle in environmental law and, to this end, must rely on maps depicting the spatial patterns of ecological attributes of aquatic and terrestrial ecosystems and of environmental change effects, respectively. In this context, different mapping techniques are presented by example of three case studies covering terrestrial, coastal and marine environments. The first case study was selected to demonstrate how to compute an ecological land classification of Germany by means of CART. The resulting ecoregions were mapped by GIS. This CARTography enables to regionalise metal bioaccumulation data in terms of 21 ecological land categories and to prove the specifity of emission control measures as being part of environmental policies. The second investigation was chosen to apply for the first time in Germany the regionalisation approach to the research of climate change effects in terms of past, recent and potential future incidences of Anopheles sp. and malaria in Lower Saxony. To investigate whether malaria might be transmitted due to increasing air temperatures, data sets on past and future air temperatures were used to spatially model malaria risk areas. The third example demonstrates the transfer of the CARTography approach presented in the first case study from terrestrial to marine environments. We analysed the statistical relations between data on benthic communities and physical properties of their marine environments by means of CART and applied these rules to geodata which only describe physical characteristics of the benthic habitats. By this, those parts of the sea ground could be predicted where certain benthic communities might occur.
From ecosystem ecology to landscape ecology: A progression calling for a well-founded research and appropriate disillusions
Authors: Ferrari Ireneo , Ferrarini Alessandro
Published: September 2008

In this paper, 1) a delineation of main theoretical, methodological and applicative issues of landscape ecology, 2) a comparison between landscape and ecosystem ecology, 3) a critical overview of actual limits of landscape ecology, are depicted. We conclude that: a) from a theoretical viewpoint, ecosystem and landscape ecology differ since they deal with ecological topics having very different spatial and temporal scales, b) from a practical standpoint, they deal with dissimilar purposes emerging both from unlike research scales and different approaches, as the interest of landscape ecology is mainly focused on the whole ecological mosaic rather than on single components, in this view assuming an "horizontal" ecological perspective, c) transdisciplinarity is still a work in progress in landscape ecology, d) several research purposes in landscape ecology are far from being reached, e) a bridge lacks between the "horizontal" perspective adopted from landscape ecology and the "vertical" approach distinctive of ecosystem ecology, therefore, they actually behave as detached disciplines. However, in our vision, landscape ecology contains the seeds for becoming a self-contained scientific discipline as well as the interface among the distinct sectors of environmental research and planning.
Dr. Asa G. Hilliard III: Trumpeter for the Academic and Cultural Excellence of African American Children
Authors: Lemons-Smith Shonda
Published: September 2008

This article explores the scholarship of Asa G. Hilliard III on the theme of student academic and cultural excellence and the development of teachers. Throughout his career, Hilliard questioned the nation’s commitment to ensuring the academic success of all children. The premise “Do we have the will to educate all children?” is reflected throughout his work, and it is the central theme of this article. Specifically, in selected examples of his scholarship, the article highlights Hilliard’s ideas on the psychological paradigm shift required for schools and teachers to “release the genius” of every child. His vision is considered within the context of traditional notions of effective teachers and teaching. Although the article primarily focuses on education broadly, select aspects of Hilliard’s work relative to mathematics education are underscored as well.
Low frequency variability of atmospheric circulation over Europe between 1785 and 1994
Authors: Schmutz Christoph , Wanner Heinz
Published: September 2008

A decadal analysis of monthly sea level pressure fields over Europe and the adjacent North Atlantic with a correlation-based classification scheme results in 12 classes. These classes show a high variability in the frequencies of their occurrence and also in the combination between the different classes. The range of the frequency changes from one decade to another can differ up to a factor 2. The class 1 high index situation with high positive values of the North Atlantic Oscillation Index (NAOI) with a westerly flow into the continent shows an increasing frequency in the last decades, which is unique in the analyzed period of 210 years. The combinations between the different classes are not the same over the whole period of the 210 years and show differences between the 19th century and the middle of the 20th century: especially in winter, spring and autumn. In summer the most remarkable deviations are found in the Greenland Sea. While the Azores high is present very regularly, the Icelandic low almost disappears for some periods or is at least very weak. From a more theoretical point of view these changes could go together with a weakening of the thermohaline circulation. The used data set NDP-025 (Numeric Data Package) from CDIAC (Carbon Dioxide Information Analysis Center) shows statistical significant smaller variances for the reconstructed period than in the measured period especially in the border areas of the perimeter. The classes have typical temperature means for three stations in Switzerland (Basel, Geneva and Grand Saint Bernard) which differ from each other significantly. Winter temperature with an eastern European anticyclone together with a high index situation are lower compared to a similar pressure situation without the Russian anticyclone. This specific case shows that the NAOI is not very meaningful for Central and Eastern Europe. In some cases the continental signal is almost independent of the NAOI. Depending on the frequency and temperature anomalies of the different classes, these can be subdivided into two groups with high or low climate relevance concerning the temperatures. Indifferent classes have temperatures near the seasonal mean or low frequencies. Their absence has no remarkable effect on the climate. The climate of a period therefore depends on the occurrence of classes with a high climate relevance.
Improvement of glycaemic and lipid profiles with muraglitazar plus metformin in patients with type 2 diabetes: an active-control trial with glimepiride
Authors: Rubin Cindy J , Ledeine Jean-Marie , Fiedorek Fred T
Published: September 2008

The efficacy and safety of muraglitazar versus glimepiride were evaluated in patients with type 2 diabetes. After open-label metformin monotherapy, 1,805 patients received randomised therapy with muraglitazar 2.5 mg or 5 mg or with glimepiride 1 mg in a doubleblind 52-week study. The primary end point was change in glycosylated haemoglobin (HbA1C); secondary end points were changes in fasting lipid levels and glycaemic indices.

At week 52, the reduction in HbA1C with muraglitazar 5 mg plus metformin was superior (p<0.0001) and with muraglitazar 2.5 mg it was non-inferior in comparison with glimepiride. At week 12, muraglitazar significantly decreased triglyceride levels (p<0.0001) and increased levels of high-density lipoprotein cholesterol (HDL-C) (p<0.0001). Oedema, weight gain and heart failure were more evident with muraglitazar. Muraglitazar 5 mg plus metformin significantly improved HbA1C, triglyceride and HDL-C levels in patients with type 2 diabetes. Cardiovascular events were similar among groups (∼2%), but there was an imbalance of total mortality in favour of glimepiride.
Endogenous secretory RAGE but not soluble RAGE is associated with carotid atherosclerosis in type 1 diabetes patients
Authors: Katakami Naoto , Matsuhisa Munehide , Kaneto Hideaki , Matsuoka Taka-Aki , Sakamoto Ken'Ya , Yasuda Tetsuyuki , Yamasaki Yoshimitsu
Published: September 2008

Advanced glycation end-products (AGEs) and the receptor for AGEs (RAGE) system play an important role in the development of diabetic complications. The soluble form of RAGE (sRAGE) that potentially counteracts AGEs consists of several forms, including endogenous secretory RAGE (esRAGE; a splice variant of RAGE) and cleaved-type soluble RAGE derived from cell-surface RAGE. The aim of this study was to compare sRAGE and esRAGE directly in patients with type 1 diabetes.

The associations of both total sRAGE and esRAGE with markers of glycaemic control and with carotid intimamedia thickness (IMT) as a marker of atherosclerosis were examined in 130 type 1 diabetes patients (aged 23.6±4.9 years) and 22 age-matched non-diabetic subjects.

IMT was inversely correlated with esRAGE (r=−0.254, p=0.0015) but neither with sRAGE nor subtracted soluble RAGE values (that is, circulating total sRAGE values – circulating esRAGE values). Furthermore, a stepwise multivariate regression analysis revealed that esRAGE (F=7.3), but not sRAGE, was a variable that interacted independently of IMT.

It is likely that circulating sRAGE and esRAGE are distinct markers and that circulating esRAGE levels, but not sRAGE levels, are associated with the status of early-stage atherosclerosis.
Role of Risk Communication in a Comprehensive Risk Management Approach
Authors: Jardine Cynthia G.
Published: September 2008

Risk communication is now seen as a reciprocal exchange of information between all interested and affected parties that serves to inform them about the risk issue. It is also generally acknowledged that successful risk management requires the incorporation of risk communication as an integral component of the risk process, from the critical stage of problem formulation through to the final selection of risk‐management options. However, while this knowledge is becoming more generally accepted, it is not being consistently employed in practice.
Axiomatic Models of Perceived Risk
Authors: Jia Jianmin , Dyer James S. , Butler John C.
Published: September 2008

This article presents two classes of measures for perceived risk based on decomposition of a lottery into its mean and its dispersion about the mean, or standard risk. One of the classes of risk measures presumes that there is no risk when there is no uncertainty involved, and the other allows different degenerate lotteries to be evaluated with different values of “risk.” The former has more prescriptive appeal in risky decision making, but the latter may have more descriptive power for subjective risk judgments. These risk measures can also incorporate the asymmetric effects of losses and gains on perceived risk when an appropriate form of the standard measure of risk is applied. These perceived‐risk models unify a large body of empirical evidence regarding risk judgments, and provide sufficient flexibility to capture better perceptions of risk than previously developed risk models. Further, they provide clear ways to accommodate financial measures of risk and psychological measures of risk, and they can be incorporated into preference models based on mean‐risk trade‐offs.
Compensation for Loss of Life and Limb
Authors: Grossman Helene L.
Published: September 2008

This article discusses the direct economic costs, indirect economic costs, and noneconomic costs associated with injuries and fatalities. Different methods for putting a value on noneconomic costs, often referred to as
pain and suffering
, are compared, and the types of compensation available for these different costs, including private insurance, public insurance, and the tort system, are examined. Next, a detailed discussion of how the tort system treats compensation for loss of life and limb is given. Finally, this article considers how life and limb are valued in other contexts, such as setting government regulations and assessing health care priorities. The focus is on the United States.
Enterprise Risk Management (
ERM
)
Authors: Ai Jing , Brockett Patrick L.
Published: September 2008

Enterprise risk management (ERM) is a recent risk‐management technique for managing a portfolio of risks in a holistic manner. ERM has evoked interest from corporate executives, regulators, and rating agencies, among others. Under the ERM framework, corporations take on risks necessary to pursue their strategic objectives, consistent with their “risk appetite”. The core of the ERM process is efficient risk integration, in which interrelations among risks and risk prioritization are highlighted. Certain risk measures, aggregation methods, or other mathematical modeling approaches are usually involved in its implementation. Effective risk reporting and communications in a well‐designed organizational structure are also essential for the success of ERM. The ultimate goal of ERM is to move beyond the initial incentive of fulfilling a compliance need to achieve real economic value.
Toxic Torts: Implications for Risk Management
Authors: Ricci Paolo F.
Published: September 2008

Toxic tort law concerns past and, in some limited instances, feared future injuries from exposure to toxicants and carcinogens generally produced, emitted, or disposed in ways that (are alleged to) contravene certain social norms. This article introduces aspects of the law of torts that relate exposures to noxious agents to their adverse effects. Examples from the United States, United Kingdom, and Australia illustrate differences among jurisdictions and modern views of the interactions between science and law.
Managing Foodborne Risk
Authors: Cox Louis A.
Published: September 2008

This article discusses quantitative risk assessment (QRA) for foodborne risks, focusing primarily on risk from disease‐causing bacteria in food. QRA can support improved risk‐management decisions for food safety by predicting the probable consequences for human health of alternative interventions, such as different standards for the maximum times and temperatures at which ready‐to‐eat foods may be refrigerated before being disposed of. Even when QRA is impracticable, process quality improvement ideas and methods can often be used to reduce microbial loads at critical control points, as emphasized in hazard analysis and critical control point (HACCP) programs, leading to safer food even without quantitative risk estimates.
Managing Risks of Consumer Products
Authors: Iyer Madhu , Zhao Ke , Steffey Duane L.
Published: September 2008

Manufacturers manage product risks by identifying, assessing, mitigating, and communicating those risks to consumers, regulatory agencies, and other stakeholders. Unforeseen risks may surface after the product has reached the market, and the manufacturer begins to receive information from field returns or customer complaints. Although the primary concern is public safety, manufacturers may also be concerned about financial risks. A product with poor reliability can increase warranty costs, damage the company's reputation, and cause a loss in market share. A safety recall can expose the manufacturer to product liability lawsuits and, for public companies, can significantly affect market valuation. Managing consumer product risk effectively involves collecting and analyzing field performance data, as well as communicating relevant data to regulatory authorities. Risk analysts have developed several semiquantitative and graphical methods to communicate product‐related safety risk to regulatory officials and consumers and to assist in determining which actions, if any, are required to protect public safety.
Product Risk Management: Testing and Warranties
Authors: Chan Wai
Published: September 2008

Manufacturers employ various testing strategies to identify and rectify defects before products are released to the markets. A carefully planned test strategy can improve product quality and customer satisfaction and reduce life cycle cost. Testing can also help reveal potential hazards associated with a product, evaluate associated risks, and discover factors that can be controlled to reduce risks. This article presents some of the tests that are performed during the prototype and production phases. These include the design verification test (DVT) and the highly accelerated life test (HALT) during the prototype phase; and the reliability qualification test (RQT) and the ongoing reliability test (ORT) in the production phase. We also describe how the results of a warranty performance analysis can be used as feedback to improve the test coverage for the tests run during production.
Computer Security: A Historical Perspective
Authors: Schell Roger R. , Reed Edwards E.
Published: September 2008

The pervasive dependence on computers today gives us no choice but to use them in the face of professional attackers. That threat, for which software subversion is often the tool of choice, is serious and growing, so computers are increasingly a major source of risk. Responsible risk assessment and risk management requires that we not only create computers that are secure but also verify that we have succeeded. A productive history of more than 30 years of research and practical experience has produced a theory of computer security rich with solutions and tools. The greatest achievement is the demonstrated ability to build and operationally deploy truly bulletproof systems having verifiable protection. This remains the most powerful solution available for many of today's hard computer and network security problems.
Cyber Risk Management
Authors: Wallner James
Published: September 2008

In most modern information systems (IS) and process control systems (PCS), functionality and security are competing design goals. Therefore, system designers and operators are constantly forced to make security‐related trade‐off decisions. To reach the right balance between functionality and security, systems security engineers and network operators have to build information and process control systems that are secure against real‐world cyber attacks without overengineering against any particular one. By understanding which cyber attacks are most likely and which risks are most serious, system designers and operators can make informed security‐related trade‐off decisions.
Cyber risk management
is the process of studying the threats, vulnerabilities, and mission impacts of cyber attacks that provides the appropriate metric for trading off between the competing design goals of security and functionality of information and process control systems.
Benchmark Dose Estimation
Authors: Al‐Saidy Obaid M.
Published: September 2008

The benchmark dose (BMD) methodology is a statistical procedure, first proposed by Crump in 1984, to determine allowable daily intakes of chemicals. The BMD was proposed as an alternative to the no‐observed‐adverse‐effect‐level (NOAEL) approach. The procedure is now widely used in risk assessment to establish health standards and guidelines for exposure of toxins to humans or to the environment. In this article, we review the BMD procedure, give details on how to compute the BMD and BMDL for both quantal and continuous endpoints and survey some of the recent developments in benchmark dose estimation.
Disease Mapping
Authors: Lawson Andrew B.
Published: September 2008

This entry describes the range of subjects covered by the term
disease mapping
. The analysis of georeferenced health data has become very important. The areas of ecological analysis, clustering, health hazard assessment, and surveillance are all covered. The focus of relative risk modeling is also addressed.
Dose–Response Analysis
Authors: Edler Lutz
Published: September 2008

Dose‐response analysis is a substantial part of risk assessment aiming both at estimation of risk at a particular dose and at estimation of a minimum dose for a particular risk. The proof of the existence of a dose‐response relationship is a basic element of the proof of causality in experimental sciences. Dose‐response analysis requires the establishment of a dose‐response model and the availability of dose‐response data, both addressed in this chapter. Dose‐response data describe the extent of exposure of the individual subject by amounts, or concentrations of the agent. Dose‐response models are mathematical formula relating dose
D
to effect
Y
(
D
) and risk
R
(
D
), which itself is a function of the effect. The most common models are provided in explicit form. Finally, the procedure of a dose‐response analysis is described in generic terms and the methods of statistical inference are addressed.
Extremely Low Frequency Electric and Magnetic Fields
Authors: Kheifets Leeka , Mezei Gabor
Published: September 2008

Extremely low frequency (ELF) electric and magnetic fields (EMFs) are imperceptible and are ubiquitously present in modern societies. Numerous epidemiologic studies have investigated possible health risks from residential and occupational exposure to EMFs. ELF magnetic fields have been classified as a “possible human carcinogen”. This classification was based on epidemiologic evidence showing a consistent association between exposure to ELF magnetic fields and childhood leukemia and on laboratory studies in animals and cells, which do not support an association between exposure to ELF magnetic fields and cancer development. Data for other health outcomes is negative or inconsistent. Several risk characterization attempts have indicated that the public health impact of residential magnetic fields on childhood leukemia is likely to be limited and uncertain.
Environmental Health Triage, Chemical Risk Assessment For
Authors: Bogen Kenneth T.
Published: September 2008

Most chemical risk assessments incorporate large uncertainties that are usually addressed by “safety” factors intended to guarantee acceptable levels of risk. An unbiased, quantitative approach to chemical risk assessment may be preferable when circumstances require balancing or trading off different risks that involve toxic chemical exposures. If planners and responders cannot reliably compare chemical risks, or compare chemical
versus
nonchemical risks, they cannot prevent or minimize associated casualties in a risk‐based fashion. These ideas are illustrated by an example of unbiased risk assessment comparing exposure to methyl isocyanate
versus
hydrogen cyanide in a triage context.
Statistics for Environmental Justice
Authors: Waller Lance A.
Published: September 2008

We briefly review the historical, legal, and regulatory background of environmental justice assessments, paying particular attention to the role of statistical techniques in such assessments. We stress the difference between “disparate impact” and intentional discrimination and the role of statistical comparisons as defined in the associated regulatory statutes. We contrast two general approaches, the first comparing demographic proportions within exposure categories and the second comparing exposure (or exposure surrogate) distributions between demographic categories.
Environmental Performance Index
Authors: Srebotnjak Tanja
Published: September 2008

The Pilot 2006 Environmental Performance Index (EPI) is an aggregate measure of a country's policy results to achieve 16 performance targets in protecting human environmental health and maintaining ecological vitality. The objective underlying the EPI is to move the environmental debate from emotional and rhetoric arguments to more data‐ and evidence‐based action that facilitates performance tracking and accountability of decision makers. The EPI thereby helps to fill a significant gap in environmental policy making and supports the international community's ongoing effort to curb extreme poverty and promote human development through an ambitious measurement initiative called the
Millennium Development Goals
.
Environmental Tobacco Smoke
Authors: Hackshaw Allan
Published: September 2008

Breathing other people's tobacco smoke is associated with several thousand premature deaths each year among nonsmoking adults, including lung cancer, heart disease, chronic obstructive lung disease and stroke in adults, and several respiratory disorders in children. There is biological plausibility and direct estimates of the increased risk have been obtained from epidemiological studies of never‐smokers. Reducing exposure to environmental tobacco smoke by banning smoking in workplaces and enclosed public places is now part of public health policy in several countries. As a consequence, this should avoid many cases of early death and disability.
Statistics for Environmental Toxicity
Authors: Bailer A. John , Oris James T.
Published: September 2008

Environmental toxicity refers to the impact of a hazard or stressor at all levels of biological organization. This impact can range from molecular and cellular levels to whole organism, population, ecosystem, or landscape levels. The statistical methods employed to examine these impacts will reflect the spectrum of the level of organization and the measurements taken at this level. The methods associated with this spectrum are described and illustrated in this article.
Pesticide Risk
Authors: Peterson Robert K.D.
Published: September 2008

Pesticides are substances that are made to deliberately kill or deter species that humans have designated as pests. And, these organism‐killing substances are intentionally disseminated into the environment. Because of these rather unusual aspects, pesticide risk assessment is straightforward, yet, at the same time, complex. Pesticide risk assessment typically follows the well‐known steps in environmental risk assessment: problem formulation, hazard identification, dose–response assessment, exposure assessment, and risk characterization. Additionally, assessments often rely on a tiered modeling approach extending from deterministic models (Tier 1) based on conservative assumptions to probabilistic models (Tier 4) using refined assumptions. Risk characterization often involves determining the joint probability of effect and exposure. A rich database of effect and exposure data for pesticides allows for risk assessments for many different human and ecological receptors; probabilistic assessments are thus becoming more common. Pesticide risk assessment continues to progress with changes in pesticide and risk assessment technologies.
Radon
Authors: Ginevan Michael E.
Published: September 2008

This entry discusses radon, which most experts believe is, after cigarette smoking, the second leading cause of lung cancer. Risk assessment issues discussed include lung dosimetry, the form of the dose‐response function relating lung‐cancer risk to radon exposure, and the interaction between radon exposure and cigarette smoking.
Environmental Remediation
Authors: Stein Alfred , Kerle Norman
Published: September 2008

This entry gives an overview of environmental remediation, with an emphasis on soil issues. The concept of risk is defined, followed by different ways of modeling (deterministic, probabilistic, and hybrid). A distinction is made between
in situ
and
ex situ
remediation and issues of spatial statistics are included. The issue is illustrated with an example on an environmental cost model.
Risk–Benefit Analysis for Environmental Applications
Authors: Gaylor David W.
Published: September 2008

The issue examined in a risk–benefit or risk–risk analysis is the trade‐off between losses suffered from illnesses or diseases, perhaps due to exposures to an environmental contaminant, and losses due to toxic effects induced by environmental remediation, e.g., chemicals used in cleanup or disinfectants employed to reduce microbial exposures. Risks and benefits may be incurred by different individuals. A management or societal issue arises as to whether the benefits (e.g., reductions of the severity or incidences of illnesses, diseases, or death) outweigh the risks introduced by interventions, e.g., disinfectant by‐products from chemicals used for drinking water treatment. A risk–benefit issue also arises for drugs with side effects and vitamins or essential minerals that become toxic at high doses. A procedure is described for estimating the optimum dose for a chemical intervention, drug, vitamin, or essential mineral that minimizes the total expected loss from the risk of an illness or disease and the loss induced by chemical, drug, or dietary intervention.
Spatial Risk Assessment
Authors: Lawson Andrew B.
Published: September 2008

The spatial analysis of risk is defined as the analysis of georeferenced data pertaining to some adverse outcome. Approaches used for this usually lie in the area of clustering methodology either as hypothesis tests or modeling of risk itself. For fixed spatial sites, and clustering around these, there are well‐developed methods related to distance and direction that can be used. When a focus site is not available, more sophisticated models or scan tests must be employed.
Threshold Models
Authors: Kopp‐Schneider Annette
Published: September 2008

Dose–response models link the dose of an agent to the effect observed in the organism it is administered to. They constitute the central ingredient for risk assessment and are used for estimation of dose corresponding to a specified risk of an adverse effect. Threshold models assume that doses below a threshold,
d
*, lead to the same response as background. Alternatively, a less stringent definition of threshold model requires that the first derivative of response with respect to dose, i.e., the rate of change in response is zero at dose 0. If threshold doses exist and can be estimated, safe exposure levels can be derived, leading to tolerable small exposures. Hence, it is essential for quantitative risk assessment for a specific agent to resolve the question as to whether it exhibits threshold behavior.

Apparent thresholds may be observed in the statistical evaluation if organisms receiving a positive dose show no statistically significant difference in response compared to background. Theoretical arguments have been collected to support the existence of thresholds. Possible threshold mechanisms include metabolic inactivation of the compound, DNA repair, cell cycle arrest, apoptosis of damaged cells, and control of the immune system. The discussion about the existence of thresholds has been closely related to the discussed distinction between genotoxic and nongenotoxic carcinogenic compounds.
Actuary
Authors: Eyland Arne , Lillevold Pål
Published: September 2008

An actuary is educated in the theory and application of mathematics, statistics, economics, probability, and finance. Using sophisticated analytical techniques, actuaries confidently make financial sense of the short term as well as the distant future by identifying, projecting, and managing a spectrum of contingent and financial risks. Life insurance, general insurance, and pension funds have been the traditional working fields of actuaries, and over the recent years it has become more common to employ actuaries also in the wider financial industry.
Comonotonicity
Authors: Dhaene Jan , Vanduffel Steven , Goovaerts Marc J.
Published: September 2008

In an actuarial or financial context it is often necessary to calculate the distribution function or risk measures for random variables of the type

where the marginal distributions of the
X

i

are known but their dependence structure is too difficult to work with. Comonotonicity, which is an extremal form of positive dependence, can be useful to determine easily computable and accurate upper and lower bounds for the distribution of
S
, and hence also for risk measures related to
S
.
Fraud in Insurance
Authors: Guillen Montserrat , Ayuso Mercedes
Published: September 2008

Insurance fraud occurs when the insurer does not know all the facts about the insured and the claim, and when the fraudster believes that some monetary benefits can be gained by distortion of such facts. We explain how fraud can be fought with deterrence and detection, and present several ways to control fraud, specialized investigation units, statistical analysis of claims information, and fraud detection methods, together with the ways for evaluation of their performance and some hints for their practical implementation. Also, we give an overview of the claims handling process. We describe various types of fraud currently encountered in insurance and give examples.
Inequalities in Risk Theory
Authors: Frostig Esther
Published: September 2008

There is a belief that heterogeneity in a portfolio increases its risk. This paper examines if this belief holds. We examine the impact of various types of heterogeneity on risk measures in the individual model, collective risk model, and life insurance. In order to measure heterogeneity, we apply majorization and Schur functions.
Nonlife Insurance Markets
Authors: Holtan Jon
Published: September 2008

The article describes market characteristics and operational business strategies in nonlife insurance from a risk assessment point of view. The first part highlights general market characteristics like regulations and legislations; profitability and underwriting cycles; market rivalry and entry dynamics; as well as other more specific characteristics like moral hazard, adverse risk selection, and uninsurable risks. The second part describes pricing and underwriting; distribution and sales; and risk and capital management as three main competitive market levers of nonlife insurance suppliers. Market outlook and trends are finally commented.
Pricing of Life Insurance Liabilities
Authors: Biffis Enrico
Published: September 2008

We describe how traditional insurance contracts can be priced by adopting a market‐consistent approach. In particular, we examine the impact of interest rate risk, mortality risk, portfolio size and heterogeneity of sums assured on the insurer's liabilities.
Distributions for Loss Modeling
Authors: Panjer Harry H.
Published: September 2008

We illustrate families of continuous and discrete distributions commonly used in modeling the size and number of (nonnegative) losses in applications including operational risk management and insurance.
Optimal Risk‐Sharing and Deductibles in Insurance
Authors: Aase Knut K.
Published: September 2008

Risk sharing in insurance is analyzed, with a view toward explaining the prevalence of deductibles.

First we introduce, in a modern setting, the main concepts of the theory of risk sharing in a group of agents. We apply this theory to the risk‐sharing problem between an insurer and an insurance customer. We develop the concept further through simple examples, illustrating some of the subtle points of this theory.

To deduce deductibles endogenously, not explained in the neoclassical model, we separately introduce (a) the insurable asset as a decision variable, (b) administrative costs, and (c) moral hazard, and illustrate these with the help of examples.
Options and Guarantees in Life Insurance
Authors: Ballotta Laura , Haberman Steven
Published: September 2008

This article gives an overview of the types of options and guarantees that are commonly part of the design of modern long‐term life insurance contracts. We provide a broad presentation of the main types of option and guarantee and consider the key issues of pricing and reserving using a mark‐to‐market framework.
Premium Calculation and Insurance Pricing
Authors: Laeven Roger J.A. , Goovaerts Marc J.
Published: September 2008

This survey of premium calculation and insurance pricing explains classical theories and their recent generalizations, summarizes main issues and results, and describes current developments in the area.
Risk Measures and Economic Capital for (Re)Insurers
Authors: Tsanakas Andreas
Published: September 2008

This contribution relates to the use of risk measures for determining (re)insurers' economic capital requirements. Alternative sets of properties of risk measures are discussed. Furthermore, methods for constructing risk measures
via
indifference arguments, representation results, and reweighting of probability distributions are presented. How these different approaches relate to popular risk measures, such as value‐at‐risk, expected shortfall, distortion risk measures, and the exponential premium principle, is also dealt with. The problem of allocating aggregate economic capital to subportfolios (e.g., insurers' lines of business) is then considered, with particular emphasis on marginal‐cost‐type methods. The relationship between insurance pricing and capital allocation is briefly discussed, based on concepts such as the opunity and frictional costs of capital and the impact of the potential of default on insurance rates.
Ruin Probabilities: Computational Aspects
Authors: Lefèvre Claude
Published: September 2008

This paper is concerned with the numerical evaluation of the probability of ruin or nonruin in insurance mathematics. Our attention is primarily focused on the classical model in collective risk theory, named the compound Poisson model. We present a review of the different methods that are usually proposed to calculate or approximate the (non)ruin probabilities, over an infinite horizon and in finite time.
Ruin Theory
Authors: Lin X. Sheldon , Willmot Gordon E.
Published: September 2008

This article gives an overview of ruin theory. It briefly discusses the probability models for the surplus process of an insurance portfolio and the mathematical tools used for the investigation of these models. An extensive list of references is provided.
Early Warning Systems (
EWSs
) for Predicting Financial Crisis
Authors: Yung Sunny W.S.
Published: September 2008

Research on the development of early warning systems (EWSs) for predicting financial crises has gathered momentum in the 1990s. EWS provides a systematic, consistent, and unbiased means to process and analyze information pertinent to financial crises. EWS build on the premise that an economy and its financial markets would behave differently prior to an imminent financial crisis. The “abnormal” behavior has a systematic and recurrent pattern. Therefore, one can judge whether a crisis is about to occur, from the movements of relevant economic and financial indicators. Recent research efforts on EWS have been focusing on currency crises. The two most extensive and well‐documented approaches are the signal approach and the limited dependent regression approach. While EWS may not be sufficiently robust to be relied upon as the sole tool to predict financial crises, they perform substantially better than nonmodel‐based forecasts in the prediction of the Asian financial crises in the late 1990s. Development in other research frameworks that are complementary to EWS is encouraging. One such effort is the resilience framework that assesses the soundness of economic and financial systems at a particular point of time rather than predicting the occurrence of financial crises.
Role of Alternative Assets in Portfolio Construction
Authors: Mulvey John M. , Kim Woo Chang
Published: September 2008

This article discusses the role of nontraditional assets in constructing a portfolio for long‐term investors. Alternative investments can provide novel patterns of returns and increase diversification benefits. In turn, investors can apply leverage in conjunction with wide diversification to improve their risk‐adjusted performance. The concepts are illustrated
via
popular categories of alternative investments. We focus on long‐term investors who are able to rebalance their portfolios on a regular basis. Careful risk management is critical in this domain.
Volatility Smile
Authors: Duan Jin‐Chuan , Li Yun
Published: September 2008

Although the Black–Scholes model lays the foundation to the modern option pricing theory, its empirical performance is rather unsatisfactory as manifested in the phenomenon known as
volatility smile
. This article explains what volatility smile is, and describes some nonparametric techniques and parametric models that may be used to deal with volatility smile for pricing and/or hedging purposes. Kernel regression and the GARCH option pricing model are chosen to be the nonparametric technique and parametric model, respectively, in our demonstration involving a sample of S&P 500 index options. Kernel regression is found to perform better than the GARCH model, but its applicability is limited to pricing the same type of options. Without providing a dynamic for the underlying asset price, kernel regression is also ill‐suited for hedging purposes. In contrast, the GARCH model is not subject to the same application limitations even though its performance on the same type of options is poorer. Thus, both nonparametric techniques and parametric models serve useful purposes in dealing with derivative contracts.
Informational Value of Corporate Issuer Credit Ratings
Authors: Rijken Herbert A. , Altman Edward I.
Published: September 2008

In the transparent capital market for US corporates, rating agencies mostly fulfill the certification needs of investors, and not the need for accurate point‐in‐time credit risk information. When ratings are used as portfolio eligibility standards set by regulators, fund trustees, or boards of directors, investors prefer stable ratings. To support this certification need Moody's and Standard & Poor's stabilize their ratings to a great extent. However, the negative impact of rating stabilization on rating timeliness and default prediction performance fully offsets the information advantage that agencies naturally have from in‐depth analysis by their ratings analysts. In a new competitive environment—after the implementation of the Credit Rating Agency Reform Act in the United States, which abandons the regulatory protection by a National Recognized Statistical Rating Organization (NRSRO) designation—rating agencies may have to push the balance between rating stability and rating timeliness more to the edge.
Credit Scoring

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Altman
Z
‐Score
Authors: Altman Edward I. , Chan Ngai H. , Wong Samuel Po‐Shing
Published: September 2008

During the last several years, assessing the probability of default (PD) and loss give default (LGD) on credit assets have become a high priority task in the internal credit risk systems of the financial institutions. Such an intense surge of interest is caused by the following factors:

A historic high in the frequency and severity of bankruptcy at the turn of the century have attracted much media attention.

Basel Accord on credit risk capital adequacy—the so‐called Basel II Accord; see Basel Commission on Banking Supervision—for banks and financial institutions to qualify for the advanced internal rating based (IRB) approach, they need to develop better assessment of PD and LGD.

To address the enormous need of PD and LGD evaluations, various quantitative techniques have been employed not only by financial institutions, but also regulatory bodies and the rating agencies. In this chapter, a brief review of the techniques of credit scoring in estimating PD is presented. For LGD computations, one can refer to Chapter 15 of Altman and Hotchkiss.
Structural Models of Corporate Credit Risk
Authors: Wong Hoi Y.
Published: September 2008

Credit risk is related to the ability of a corporation or an individual to honor a financial obligation. A typical example is the default risk embedded in corporate bond markets. Structural models of credit risk are specifically designed to describe corporate credit risk using the capital structure of a firm. The capital structure comprises the firm's underlying assets, equities, and debts. A comprehensive approach even takes into account the optimal allocation of the firm's assets, the dividend policy of the management, and protective covenants of bond holders. The Moody's KMV, a corporation owned by the Moody's Investor Services, is the first rating agency to put a structural model into commercial use since the early 1990s. Popular structural models include, but are not limited to, the Merton model, the Black–Cox model, the Leland–Toft model, and the KMV approach. In this article, a brief overview of the formulation of a structural approach, specifications within the aforementioned models, and the implementation issues is given.
Polychlorinated Biphenyls
Authors: Safe Stephen , Wu Fei
Published: September 2008

Polychlorinated biphenyls (PCBs) were widely used industrial formulations noted for their lipophilicity and stability, and these properties contributed to their use as solvents and dielectric fluids for transformers and capacitors. PCBs were first identified in the environment in the 1960s, and their subsequent detection in almost every component of the global ecosystem including fish, wildlife, and humans resulted in a ban on their manufacture and use in most countries during the 1970s. PCBs are complex mixtures of congeners, which include several nonortho‐substituted compounds such as 3, 3′, 4, 4′, 5‐pentachlorobiphenyl which bind and activate the aryl hydrocarbon receptor (AhR). The potential adverse effects of individual PCB congeners and defined mixtures on laboratory animals have identified multiple effects and toxicities. Major human health concerns are focused on neurodevelopment effects of PCBs; however, the observed effects are highly variable and require further investigation. Risk assessment of individual PCBs that are AhR agonists utilize an additive toxic equivalency factor approach; however, risk and hazard assessment of PCB mixtures and their interactions is not well defined.