Does Temporal Variation in Predation Risk Influence the Intensity of Antipredator Responses? A Test of the Risk Allocation Hypothesis

Temporal variation in predation risk may fundamentally influence antipredator responses of prey animals. To maximize lifetime fitness, prey must be able to optimize energy gain and minimize predation risk, and responses to current levels of risk may be influenced by background levels of risk. A ‘risk allocation’ model has recently been proposed to predict the intensity of antipredator responses that should occur as predation risk varies over time. Prey animals from high‐risk environments should respond to predators with relatively low intensities of antipredator behaviour because long periods of antipredator behaviour may result in unacceptable decreases in levels of foraging activity. Moreover, animals that are under frequent risk should devote more energy to foraging during brief pulses of safety compared with animals under infrequent attack. In this study, we experimentally tested the risk allocation hypothesis. We exposed juvenile rainbow trout, Oncorhynchus mykiss, to three levels of risk (high, moderate and low) crossed with two levels of temporal variation (exposed to risk three times a day and once a day). In accordance with the model, we found that trout exposed to risky situations more frequently responded with significantly less intense antipredator behaviour than trout exposed to risk infrequently. The intensity of response of trout exposed to moderate risk three times a day decreased to levels similar to situations of no risk. However, in contrast to the second prediction of the model, animals under frequent risk were not more active during periods of safety compared with animals under infrequent risk. Although behaviour in the face of predation risk was dependent on the broader temporal context in which risk varied, the specific predictions of the risk allocation model were only partly supported.     

Use of Chronic Kidney Disease to Enhance Prediction of Cardiovascular Risk in Those at Medium Risk

Based on global cardiovascular (CV) risk assessment for example using the Framingham risk score, it is recommended that those with high risk should be treated and those with low risk should not be treated. The recommendation for those of medium risk is less clear and uncertain. We aimed to determine whether factoring in chronic kidney disease (CKD) will improve CV risk prediction in those with medium risk. This is a 10-year retrospective cohort study of 905 subjects in a primary care clinic setting. Baseline CV risk profile and serum creatinine in 1998 were captured from patients record. Framingham general cardiovascular disease risk score (FRS) for each patient was computed. All cardiovascular disease (CVD) events from 1998–2007 were captured. Overall, patients with CKD had higher FRS risk score (25.9% vs 20%, p = 0.001) and more CVD events (22.3% vs 11.9%, p = 0.002) over a 10-year period compared to patients without CKD. In patients with medium CV risk, there was no significant difference in the FRS score among those with and without CKD (14.4% vs 14.6%, p = 0.84) However, in this same medium risk group, patients with CKD had more CV events compared to those without CKD (26.7% vs 6.6%, p = 0.005). This is in contrast to patients in the low and high risk group where there was no difference in CVD events whether these patients had or did not have CKD. There were more CV events in the Framingham medium risk group when they also had CKD compared those in the same risk group without CKD. Hence factoring in CKD for those with medium risk helps to further stratify and identify those who are actually at greater risk, when treatment may be more likely to be indicated.     

Understanding predation risk and individual variation in risk avoidance for threatened boreal caribou

Predation risk is a driver of species’ distributions. Animals can increase risk avoidance in response to fluctuations in predation risk, but questions remain regarding individual variability and the capacity to respond to changes in spatial risk across human‐altered landscapes. In northeast British Columbia, Canada, boreal caribou populations declined as roads and seismic lines have increased, which are theorized to increase gray wolf predation. Our goal was to model risk and to evaluate individual variability and the development of risk perception by examining individual risk avoidance in response to reproductive status and age. We used locations from collared caribou and wolves to identify landscape features associated with the risk of a potential wolf‐caribou encounter and risk of being killed given an encounter. We built resource selection functions to estimate individual responses to risk. We used general linear regressions to evaluate individual risk and linear feature avoidance as a function of age and reproductive status (calf or no calf). Linear features increased the risk of encounter. Older caribou and caribou with calves demonstrated stronger avoidance of the risk of encounter and roads, but weaker avoidance in late summer to the risk of being killed relative to younger and calf‐less individuals. Mechanisms explaining the inverse relationships between the risk of encounter and risk of being killed are uncertain, but it is conceivable that caribou learn to avoid the risk of encounter and roads. Responses by females with vulnerable calves to the risk of encounter and risk of being killed might be explained by a trade‐off between these two risk types and a prioritization on the risk of encounter. Despite the capacity to alter their responses to risk, the global decline in Rangifer populations (caribou and wild reindeer) suggests these behaviors are insufficient to mitigate the impacts of anthropogenic disturbances.     

Perspectives on environmental risk assessment

Risk is by no means a simple concept. Natural variability and definitional problems with the concept of probability complicate the measurement and use of risk as an analytical tool. Variability requires that risk assessment methods separate natural from total risk when attempting to estimate anthropogenic risk. Failure to do so results in the over estimation of anthropogenic risk and the eventual loss of credibility for risk assessment methodologies. The common frequentist approach to probability is not consistent with anything but a modelling approach to risk assessment. When combined with its ability to account for natural variability, incorporate laboratory-assay data and offer complete statistical and experimental control, modelling is a promising approach to risk assessment. Modelling, however, is not without its drawbacks. Initialization bias can result in the over, or under, estimation of both natural and anthropogenic risk. Furthermore, model estimates are time dependent. The convergence of natural and anthropogenic risk poses problems for modelling-based risk assessment and requires clear statements as to the importance of the time dimension in risk assessment. When combined, the drawbacks to modelling-based risk assessment argue that risk should never be stated as a scalar quantity. Instead, modelling-based risk assessment should provide estimates of the complete range of risk measures (total, natural, and anthropogenic) as well as indications of convergence time. Only then can the modelling-based approach be viewed as the most appropriate means of carrying out scientifically credible risk assessment.     

Epidemiological evaluation of the use of genetics to improve the predictive value of disease risk factors.

The prevention of common diseases relies on identifying risk factors and implementing intervention in high-risk groups. Nevertheless, most known risk factors have low positive predictive value (PPV) and low population-attributable fraction (PAF) for diseases (e.g., cholesterol and coronary heart disease). With advancing genetic technology, it will be possible to refine the risk-factor approach to target intervention to individuals with risk factors who also carry disease-susceptibility allele(s). We provide an epidemiological approach to assess the impact of genetic testing on the PPV and PAF associated with risk factors. Under plausible models of interaction between a risk factor and a genotype, we derive values of PPV and PAF associated with the joint effects of a risk factor and a genotype. The use of genetic testing can markedly increase the PPV of a risk factor. PPV increases with increasing genotype-risk factor interaction and increasing marginal relative risk associated with the factor, but it is inversely proportional to the prevalences of the genotype and the factor. For example, for a disease with lifetime risk of 1%, if all the risk-factor effect is confined to individuals with a susceptible genotype, a risk factor with 10% prevalence and disease relative risk of 2 in the population will have a disease PPV of 1.8%, but it will have a PPV of 91.8% among persons with a genotype of 1% prevalence. On the other hand, genetic testing and restriction of preventive measures to those susceptible may decrease the PAF of the risk factor, especially at low prevalences of the risk factor and genotype.(ABSTRACT TRUNCATED AT 250 WORDS)     

Risk factors for acute myocardial infarction in women: evidence from the Royal College of General Practitioners' oral contraception study.

To determine the pattern of risk factors for acute myocardial infarction associated solely with women a nested case-control study was carried out on cohort data collected during the Royal College of General Practitioners'' oral contraception study. Smoking (adjusted relative risk 1.7 for light smokers and 4.3 for heavy smokers), hypertension (2.4), toxaemia of pregnancy (2.8), and diabetes mellitus (6.9) were associated with a significantly increased risk of myocardial infarction. There was no significant trend of risk with social class. Current use of the pill increased the risk only among women who also smoked (relative risk 20.8 for heavy smokers). Previous use of the pill did not influence the risk of myocardial infarction. If heavy smokers also had a history of toxaemia of pregnancy their risk of myocardial infarction was further increased (relative risk 41.0). Other variables associated solely with women, such as parity, hysterectomy, and hormone replacement therapy, had little effect on the risk of having a myocardial infarction. Overall, smoking was the most important independent risk factor and had a strong influence on risks associated with other factors.     

矿区生态风险评价研究述评

作为世界上矿产资源最丰富的国家之一,我国的矿山开采活动在给经济发展注入强大拉动力的同时,也给矿区生态环境带来了巨大的生态风险。总结前人相关研究,在对比分析了矿区生态风险及其评价与区域生态风险评价异同的基础上,初步明晰矿区生态风险具有风险源的多样性、空间影响边界的模糊性、随空间距离的衰减性及时间累积的延续性等特性。目前矿区生态风险评价的矿区类型过多集中于金属矿区的重金属污染等单项风险,对综合生态风险评价的重视不充分,多基于景观格局、生态环境问题视角,结果多对斑块或生态系统风险评价进行拼接,欠缺基于空间异质性的整体综合;风险度量模型、指标体系法和空间分析法则是较为常用的矿区生态风险评价方法,但在模型模拟方面略显不足。基于现有研究进展,预期矿区独特性的体现、空间格局的关注、"3S"技术的综合应用、生态安全阈值的设定、不确定性表征、基于评价结果的风险规避等将有望成为未来研究的重点。     

四川省盆地区玉米干旱灾害风险评估及区划

利用四川省盆地区玉米产量资料、生育期资料和相关气象资料,建立了适用于四川省盆地区玉米干旱风险评估的气候干旱风险模型、作物干旱风险模型、产量灾损风险模型、抗灾性能模型和相应的指标体系,并构建了四川省盆地区玉米旱灾综合风险评估模型,确定了综合风险区划指标.结果表明： 四川省盆地区玉米各项风险评估指标具有明显的区域差异和一定的连片性;玉米旱灾综合风险评价指标,可将四川省盆地区玉米种植区划分为高、中、低3个风险区,其中,风险高值区主要集中在盆西北大部、盆中及盆南部分地区,风险中值区主要分布在盆北及盆南部分地区,风险低值区主要分布在盆东北、盆西南及盆东南部分地区.     

Fluorescent lights,ultraviolet lamps,and risk of cutaneous melanoma.

Exposure to solar radiation is increasingly being associated with a risk of cutaneous melanoma, and some risk has also been attributed to exposure to fluorescent lights. The risk of cutaneous melanoma associated with exposure to some sources of artificial ultraviolet radiation was examined in a case-control study in a Scottish population with fairly low exposure to natural ultraviolet radiation. The risk was not significantly or consistently raised for exposure to fluorescent lights at home or at work. The use of ultraviolet lamps and sunbeds, however, was associated with a significantly increased risk (relative risk = 2.9; 95% confidence interval 1.3 to 6.4), and the risk was significantly related to duration of use. The risk was particularly raised among people who have first used [corrected] ultraviolet beds or lamps more than [corrected] five years before presentation (relative risk = 9.1; 95% confidence intervals 2.0-40.6), in whom it was significantly related to cumulative hours of exposure. The risks associated with exposure to ultraviolet lamps and sunbeds remained significant after adjustment for other risk factors for melanoma.     

渤海湾港口生态风险评估

以天津港为例,利用相对风险模型(RRM)对渤海湾港口生态风险进行评价。根据RRM,将天津港划分为北疆、南疆、东疆和临港等4个风险小区。在每一风险小区中,选取2种生境类型(滩涂和近海水体)、2种风险源(船舶运输和港口码头)和3种生态终点(底栖动物、浮游植物、浮游动物),以此计算生态风险值,根据风险值高低分为高、较高、中等、低和弱5个等级。评价结果表明,在两种风险源中,船舶运输风险相对较大;在生境中,近海水体的风险值远大于滩涂;在生态终点中,风险高低为底栖动物浮游植物浮游动物。天津港生态风险可以划分为3个等级:北疆为高风险区、南疆为较高风险区、东疆和临港均为中等风险区。     

Managing concomitant cardiac disease and erectile dysfunction

Early studies of peak heart rates and blood pressure during coitus led physicians to believe that sexual activity represents a significant risk to patients with cardiovascular disease. Subsequent studies indicated, however, that the heart rate during coitus was no higher than the rate during unaccustomed physical exercise or associated with anger. The absolute risk of myocardial infarction (MI) in a patient with a history of MI has been found to be 10 per million per hour, and the doubling of this risk in the 2 hours following coitus has a negligible impact on annual risk. Coronary artery disease (CAD) is a powerful indicator of the presence of erectile dysfunction (ED), and the risk factors for ED are similar to those for CAD. Studies of sildenafil citrate use in patients with a history of cardiovascular disease have found sildenafil to be safe and effective, except for an absolute contraindication in the concomitant use of nitrates. Physicians should become familiar with the clinical guidelines for classifying ED patients with a history of cardiovascular disease as high risk, intermediate or indeterminate risk, and low risk. The guidelines permit physicians MIlow risk while deferring the resumption of sexual activity among higher risk patients pending further evaluation.     

Short-term versus long-term risk for coronary artery disease: implications for lipid guidelines

PURPOSE OF REVIEW: The aim of this article is to describe recent advances in our understanding of lifetime risks for cardiovascular disease and their implications for lipid guidelines. RECENT FINDINGS: Recent studies have indicated that, among younger and middle-aged adults, there is a large subset with low 10-year risk but high lifetime risk for cardiovascular disease. Individuals with high lifetime risks can be identified on the basis of single adverse risk factors or on the basis of overall risk factor burden. For example, using the ATP-III online risk estimator, a 45-year-old obese, nonsmoking, nondiabetic man with total cholesterol of 200 mg/dl, HDL-cholesterol of 40 mg/dl, and untreated systolic blood pressure of 135 mmHg has an estimated 10-year risk for hard coronary heart disease of 3%. In contrast, recent data indicate that his predicted remaining lifetime risk for cardiovascular disease is 50% and his predicted median survival is over 10 years shorter than a man at the same age with optimal risk factors. SUMMARY: Lifetime risk estimation for cardiovascular disease may be an important adjunct to short-term (10-year) risk estimation that may help identify more treatment-eligible individuals at risk for cardiovascular disease, improve risk communication, motivate changes in lifestyle and behaviors, and promote adherence to therapy.     

BMI and Risk Factors for Suicide: Why Is BMI Inversely Related to Suicide?

Higher BMI has been associated with a lower risk of suicide in large prospective studies, but the mechanisms for this link require elucidation. In the 2002 and 2004 iterations of the Behavioral Risk Factor Surveillance System (BRFSS), a large, population‐based telephone survey of US adults conducted by the Centers for Disease Control and Prevention, participants reported their height, weight, and several potential risk factors for suicide, including alcohol use, mental health, marital status, firearm ownership, and risk‐taking behaviors. We assessed whether BMI was associated with these risk factors among 224,247 eligible respondents in 2002 and 275,194 in 2004 after sample‐weighted adjustment for age, race, region, smoking, and education. Alcohol‐related risk factors tended to be lower with heavier BMI among women, while firearm‐related risk factors tended to be higher with heavier BMI among men. Heavier BMI also tended to be associated with unmarried status and poor mental health, especially among women, and with infrequent seat belt use in men and women. No potential risk factors were consistently inversely associated with BMI in both sexes and years. In summary, in these samples of the US population, conventional risk factors for suicide were inconsistently associated with BMI, making them unlikely mediators for the observed relationship of BMI with lower risk of suicide. In some cases, risk factors were actually greater with heavier BMI. Further study of the relationship of BMI and suicide may yield novel modifiable risk factors that could cause or prevent this important cause of death.     

Environmental Risk Controllability and Management of VOCs during Remediation of Contaminated Sites

The environmental risk controllability assessment system and its method of controlling volatile organic compounds (VOCs) during remediation of contaminated sites are established in this article based on soil vapor extraction (SVE) technology. According to the properties of VOCs and the technical and operational characteristics of the site remediation process, the environmental risk controllability index system includes environmental risk identification, risk source analysis, and risk assessment. Environmental risk management during site remediation was focused on technical control methods and engineering control technologies. Specifically, acceptance based on risk management was suitable for low-risk levels such as RRI3 and RRI4. Furthermore, control methods for high-level risk (RRI1 or RRI2) could be developed along with transformation and control, combined with the necessary emergency risk plan.     

A Risk Elimination Coordination Method for Large Group Decision-Making in Natural Disaster Emergencies

ABSTRACT

In view of the risk characteristics of large group decision-making in emergencies and the difficultly in forming the decision scheme with low risk, the causes of generating risk in urgent group decisions are analyzed. The coordination framework for risk elimination in emergency decisions is constructed. The methods of risk measure and elimination for emergency decisions are proposed to construct the risk elimination coordination mechanism for emergency decisions so that the risk of emergency group decisions is gradually constringed to obtain the emergency decision scheme with risk degree low enough. Finally, an example case is used to validate the realization process and the validity of risk elimination coordination method and mechanism.     

西藏高原拉萨河流域生态风险评估

随着我国西部崛起战略的实施,社会经济发展所引发的生态风险逐渐引起生态学者和政府管理部门的高度关注。拉萨河流域作为高原生物多样性的维持基地,也是我国及东亚的重要生态安全屏障区,为有效管控其社会经济发展中产生的生态环境风险,通过适合高寒流域特征的风险评估方法,识别了研究区风险源,选择风险受体,采用相对风险模型计算了各研究单元的风险等级。结果表明:城关区的生态风险最高,主要风险来源于城镇扩张和旅游娱乐;当雄县生态风险最低,风险来源于畜牧养殖;林周县、曲水县、达孜县、堆龙德庆区以及墨竹工卡县的首要风险源是农业污染。水体和湿地的风险值明显高于其他生态系统。风险值的空间分布表现为南高北低的特征,且风险等级以城关区为中心向外围逐渐降低。     

Subjective and objective risk of breast cancer in Ashkenazi Jewish individuals at risk for BRCA1/2 mutations

The aims of the study were to (1) examine the differences between subjective and objective estimates of the risk of breast cancer in those being tested for BRCA1/2 mutations, (2) explore new ways to conceptualize risk, and (3) examine the change in subjective risk of developing breast cancer throughout the process of genetic counseling and testing. Participants were 86 Ashkenazi Jewish women with a family or personal history indicating risk for BRCA1/2 mutations. Surveys to assess subjective risk of breast cancer (percentage risk, projected age of onset, and survival time) were administered before counseling, after counseling, and after receipt of test results. Subjective percentage risk of breast cancer was compared to estimated objective risk to determine accuracy. Those with no personal history of cancer receiving positive results became more accurate from post-counseling to post-result. Those receiving positive results increased their estimate of their percentage risk, and those receiving uninformative negative results decreased their estimate of their percentage risk from post-counseling to post-result. Those without a personal history of cancer decreased in perceived risk from post-counseling to post-result. No change in projected age of onset of breast cancer or survival time with breast cancer was seen from pre- to post-counseling or from post-counseling to post-result, and no change in accuracy or in percentage risk of breast cancer was seen from pre- to post-counseling. Individuals use information from genetic counseling to form estimates of percentage risk following receipt of test results; however, projected age of onset and survival time with breast cancer, areas not targeted by genetic counseling that may be more closely linked to health behavior, do not change.     

Protein-based HDL subspecies: Rationale and association with cardiovascular disease,diabetes, stroke,and dementia

HDL-cholesterol is associated with reduced risk of cardiovascular disease, and is used in clinical practice for risk stratification. HDL is composed of many protein-defined subspecies that each comprises just a few percent of the total, some associated with lower and some with higher risk of CVD. HDL that contains apoC3 or apoE are subspecies that have opposing actions on HDL reverse cholesterol transport and opposing associations with risk of future CVD, apoC3 adverse and apoE beneficial. In addition to coronary heart disease, HDL that contains apoC3 is associated with risk of future type 2 diabetes and insulin resistance; ischemic stroke and cerebral infarction; dementia and the deposition of beta-amyloid in the brain. HDL that contains apoE and apoE itself are associated with lower risk of dementia. Other HDL subspecies that contain complement C3, alpha-2 macroglobulin, plasminogen, or haptoglobin are associated with higher future risk of coronary heart disease, whereas others such as HDL that contains apoC1 are associated with lower risk. At this time, these findings provide improved understanding of the multifaceted HDL system to better determine risk and targeting of therapy for the most prevalent chronic lifestyle diseases in our society.     

Adolescent fertility and risky environments: a population-level perspective across the lifespan

Timing of first reproduction is a key life-history variable with important implications for global economic development and health. Life-history theory predicts that human reproductive strategies are shaped by mortality regimes. This study provides the first test of the relationship between population-level adolescent fertility (AF) and extrinsic risk at two time points. Data are from United Nations database and were analysed using mediation and moderation techniques. The goals were to determine whether (i) early risk has a stronger impact on fertility than current risk; (ii) current risk mediates the relationship between early risk and fertility outcomes; and (iii) different levels of early risk influence the relationship between current risk and fertility. Results indicated that current risk partially mediated the relationship between early risk and fertility, with early risk having the strongest impact on reproduction. Measures for early and current mortality did not show significant interaction effects. However, a series of separate regression analyses using a quantile split of early risk indicated that high levels of early risk strengthened the relationship between current risk and AF. Overall, these findings demonstrate that reproductive strategies are significantly influenced by fluctuations of early mortality as well as current environmental cues of harshness.     

Growth hormone treatment: cancer risk

There have been concerns that growth hormone (GH) therapy may be associated with an increased risk of cancer. Although data are limited and conflicting, one recent report on cancer risk in individuals with no cancer history or risk factors for cancer who were treated with pituitary GH demonstrated a small increased risk of colon cancer and deaths from colon cancer and Hodgkin disease. The data from cancer survivors have consistently shown no increased risk of recurrence of the primary tumor in survivors of all tumor types who are treated with GH. One recent study did show a small increased risk of second solid tumors in survivors previously treated with GH. Limited data suggest that GH therapy is not associated with excess cancer risk in individuals with Langerhans cell histiocytosis and neurofibromatosis type 1. Overall, the clinical data are reassuring, but continued surveillance is mandatory.