Valid historical data for probabilistic risk analysis in natural disasters

With the changes in the nature and the society, risks will inevitably change. It implies that, with the passage of time, some historical data would be invalid for probabilistic risk analysis. In this paper, a model to acquire the valid data is suggested, which is based on the Mann- Kendall test to detect abrupt change-point on time series data. What's more, the typhoon risk analysis in Guangdong Province, China is used as a case study to show how to apply the model. The valid data of the intensities of typhoons and the related losses in the province for the probabilistic risk analysis is obtained from the data during the time from 1984 to 2012. Comparing with the results based on the set of invalid data and the set of all collected data, the assessed risk based on the valid data is more reliable, which could reflect the dynamics of the typhoon risk.     

Factors Prior to Dry Period Associated with High and Low Levels of Cow Milk Somatic Cell Counts in Next Lactation

Data from a randomized controlled field study of selective dry cow therapy were used in which 686 cows had been allocated to 2 control groups (sampling only or placebo) or 2 therapy groups. Possible factors from previous lactation were assessed in determining their association with the probability of ‘failure’, designated as a cow milk somatic cell count (CMSCC) of greater than 399000 per ml in geometric mean of several measurements during subsequent lactation. Success cows were those with a CMSCC of less than 200000 per ml. For our analyses, this targeted 187 success cows and 186 failure cows. Therapy was given as a total dose of 400000 IU penicillin and 100 mg neomycin per infected quarter as dry cow preparation once, or as a lactation formula with a total dose of 1.2 million IU penicillin and 1200 mg dihydrostreptomycin per infected quarter during a 1-week period. Significant factors in the predictive model for success included therapy, low level of CMSCC (geometric mean of the 3 last tests) in previous lactation, low level of CMSCC (weighted by daily milk yield mean) in the herd, young cows, and not having had a case of treatment for chronic clinical mastitis. Additional information on the probability of failure in treated and untreated cows can be predicted by number of quarters infected with Staphylococcus aureus approximately 1.5 months before drying off. The models derived are considered for use as tools in selective treatment and culling decisions.     

Aluminum content of infant formulas used in Turkey

In the past few years, there has been an upsurge of interest in aluminum (Al) and human health. The well-recognized manifestations of systemic Al toxicity include fracturing osteomalacia, dialysis encephalopathy, and microcytic hypochromic anemia. The role of Al in causing childhood diseases is also becoming clearer, but the safe plasma level still remains to be determined in newborns, especially in premature newborns, implying that it should be kept low. Premature infants receiving iv fluid therapy show evidence of Al loading. Additionally, the infant-feeding mixtures, especially the soy-based infant formulas, tested may be a significant additional source of Al in the diet of infants with low birthweights, and in infants and in young children with impaired renal function. Careful clinical and biochemical monitoring is warranted to determine whether it will be necessary to eliminate Al contamination of both oral and parenteral preparations used in infants and children who may be at risk for Al intoxication. In this present study, the Al content of infant feeds was measured by electrothermal atomic absorption spectrophotometry, and also compared with those of breast milk, cow’s milk, milk powder, and some starches that are commonly used for preparation of infant feed in Turkey. Our results show that Al content of commercially available powdered infant formulas, most of which are imported from Europe, ranged from 1.211 to 10.925 μg/g. The mean value was higher than that of breast milk. It was also found that the Al content of cow’s milk in various containers was higher than that of breast milk. The highest Al level among cow’s milk samples was in the aluminized carton box. In the other products tested, such as milk powder, the starches contained Al at various levels. Among these, milk powder and rice flour contained a high level of Al.     

Calling at the highway: The spatiotemporal constraint of road noise on Pacific chorus frog communication

Loss of acoustic habitat due to anthropogenic noise is a key environmental stressor for vocal amphibian species, a taxonomic group that is experiencing global population declines. The Pacific chorus frog (Pseudacris regilla) is the most common vocal species of the Pacific Northwest and can occupy human‐dominated habitat types, including agricultural and urban wetlands. This species is exposed to anthropogenic noise, which can interfere with vocalizations during the breeding season. We hypothesized that Pacific chorus frogs would alter the spatial and temporal structure of their breeding vocalizations in response to road noise, a widespread anthropogenic stressor. We compared Pacific chorus frog call structure and ambient road noise levels along a gradient of road noise exposures in the Willamette Valley, Oregon, USA. We used both passive acoustic monitoring and directional recordings to determine source level (i.e., amplitude or volume), dominant frequency (i.e., pitch), call duration, and call rate of individual frogs and to quantify ambient road noise levels. Pacific chorus frogs were unable to change their vocalizations to compensate for road noise. A model of the active space and time (“spatiotemporal communication”) over which a Pacific chorus frog vocalization could be heard revealed that in high‐noise habitats, spatiotemporal communication was drastically reduced for an individual. This may have implications for the reproductive success of this species, which relies on specific call repertoires to portray relative fitness and attract mates. Using the acoustic call parameters defined by this study (frequency, source level, call rate, and call duration), we developed a simplified model of acoustic communication space–time for this species. This model can be used in combination with models that determine the insertion loss for various acoustic barriers to define the impact of anthropogenic noise on the radius of communication in threatened species. Additionally, this model can be applied to other vocal taxonomic groups provided the necessary acoustic parameters are determined, including the frequency parameters and perception thresholds. Reduction in acoustic habitat by anthropogenic noise may emerge as a compounding environmental stressor for an already sensitive taxonomic group.     

Chaotic neural network applied to two-dimensional motion control

Chaotic dynamics generated in a chaotic neural network model are applied to 2-dimensional (2-D) motion control. The change of position of a moving object in each control time step is determined by a motion function which is calculated from the firing activity of the chaotic neural network. Prototype attractors which correspond to simple motions of the object toward four directions in 2-D space are embedded in the neural network model by designing synaptic connection strengths. Chaotic dynamics introduced by changing system parameters sample intermediate points in the high-dimensional state space between the embedded attractors, resulting in motion in various directions. By means of adaptive switching of the system parameters between a chaotic regime and an attractor regime, the object is able to reach a target in a 2-D maze. In computer experiments, the success rate of this method over many trials not only shows better performance than that of stochastic random pattern generators but also shows that chaotic dynamics can be useful for realizing robust, adaptive and complex control function with simple rules.     

Sucking motivation and related problems in calves

Since survival of the young mammals depends on sucking success, it is assumed that sucking motivation must be strong and that sucking deprivation would result in frustration which could have a negative impact on their welfare. This concern as well as that regarding cross-sucking between calves and intersucking between older animals has stimulated research on the motivation of calves for non-nutritive sucking. Non-nutritive sucking is elicited by the ingestion of milk, and the lactose concentration in milk, rather than that of fat or protein, is the main factor stimulating non-nutritive sucking. Every time a calf drinks milk, it is stimulated to suck and deprivation of sucking may interfere with digestive processes or satiety. To understand the behaviour of the calf during nutritive sucking, we examined the effects of milk flow on calves' sucking and butting an artificial feeding system. Slowing and stopping the flow rate stimulates butting and can lengthen the duration of sucking for the meal. It also stimulates the calf to switch teats when a second teat is available. These findings are well correlated to our observations of the calf suckling a cow in experimental manipulations. The duration of the meal is not correlated with milk intake, but it is influenced by milk availability and how hungry the calf is. Furthermore, calves will butt more often when there is less milk available in the dam's udder, presumably because milk flow is slower. Consequently, it is the occurrence of butting rather than sucking duration that would be a good indicator of milk intake when the calf is suckling the dam. Finally, we recommend a combination of slower milk flow and hay feeding and the provision of a non-nutritive artificial teat to reduce the occurrence of cross-sucking following a milk meal.     

How Much Compensation is Enough? A Framework for Incorporating Uncertainty and Time Discounting When Calculating Offset Ratios for Impacted Habitat

Biodiversity offset areas may compensate for ecological damage caused by human activity elsewhere. One way of determining the offset ratio, or the compensation area needed, is to divide the present conservation value of the development site by the predicted future conservation value of a compensation area of the same size. Matching mean expected utility in this way is deficient because it ignores uncertainty and time lags in the growth of conservation value in compensation areas. Instead, we propose an uncertainty analytic framework for calculating what we call robustly fair offset ratios, which guarantee a high enough probability of the exchange producing at least as much conservation value in the offset areas than is lost from the development site. In particular, we analyze how the fair offset ratio is influenced by uncertainty in the effectiveness of restoration action, correlation between success of different compensation areas, and time discounting. We find that very high offset ratios may be needed to guarantee a robustly fair exchange, compared to simply matching mean expected utilities. These results demonstrate that considerations of uncertainty, correlated success/failure, and time discounting should be included in the determination of the offset ratio to avoid a significant risk that the exchange is unfavorable for conservation in the long run. This is essential because the immediate loss is certain, whereas future gain is uncertain. The proposed framework is also applicable to the case when offset areas already hold conservation value and do not require restoration action, in which case uncertainty about the conservation outcome will be lower.     

Pine invasions in the southern hemisphere: modelling interactions between organism,environment and disturbance

Current theories of plant invasion have been criticized for their limited heuristic and predictive value. We explore the heuristic and predictive potential of a model which explicitly simulates the mechanisms of plant invasion. The model, a spatially-explicit individual-based simulation, is applied to the invasion of pine trees (Pinus spp.; Pinaceae) in three vegetation types in the southern hemisphere. The model simulates factors which have been invoked as major determinants of invasive success: plant traits, environmental features and disturbance level. Results show that interactions between these determinants of invasive success are at least as important as the main effects. The complexity of invasions has promoted the belief that many factors must be invoked to explain invasions. This study shows that by incorporating interactions and mechanisms into our models we can potentially reduce the number of factors needed to predict plant invasions. The importance of interactions, however, means that predictions about invasions must be context-specific. The search for all-encompassing rules for invasions is therefore futile. The model presented here is of heuristic value since it improves our understanding of invasions, and of management value since it defines the data and models needed for predicting invasions.     

Quasi-likelihood estimation for relative risk regression models

For a prospective randomized clinical trial with two groups, the relative risk can be used as a measure of treatment effect and is directly interpretable as the ratio of success probabilities in the new treatment group versus the placebo group. For a prospective study with many covariates and a binary outcome (success or failure), relative risk regression may be of interest. If we model the log of the success probability as a linear function of covariates, the regression coefficients are log-relative risks. However, using such a log-linear model with a Bernoulli likelihood can lead to convergence problems in the Newton-Raphson algorithm. This is likely to occur when the success probabilities are close to one. A constrained likelihood method proposed by Wacholder (1986, American Journal of Epidemiology 123, 174-184), also has convergence problems. We propose a quasi-likelihood method of moments technique in which we naively assume the Bernoulli outcome is Poisson, with the mean (success probability) following a log-linear model. We use the Poisson maximum likelihood equations to estimate the regression coefficients without constraints. Using method of moment ideas, one can show that the estimates using the Poisson likelihood will be consistent and asymptotically normal. We apply these methods to a double-blinded randomized trial in primary biliary cirrhosis of the liver (Markus et al., 1989, New England Journal of Medicine 320, 1709-1713).     

Informed renesting decisions: the effect of nest predation risk

Animals should cue on information that predicts reproductive success. After failure of an initial reproductive attempt, decisions on whether or not to initiate a second reproductive attempt may be affected by individual experience and social information. If the prospects of breeding success are poor, long-lived animals in particular should not invest in current reproductive success (CRS) in case it generates costs to future reproductive success (FRS). In birds, predation risk experienced during breeding may provide a cue for renesting success. Species having a high FRS potential should be flexible and take predation risk into account in their renesting decisions. We tested this prediction using breeding data of a long-lived wader, the southern dunlin Calidris alpina schinzii. As predicted, dunlin cued on predation risk information acquired from direct experience of nest failure due to predation and ambient nest predation risk. While the overall renesting rate was low (34.5 %), the early season renesting rate was high but declined with season, indicating probable temporal changes in the costs and benefits of renesting. We develop a conceptual cost-benefit model to describe the effects of the phase and the length of breeding season on predation risk responses in renesting. We suggest that species investing in FRS should not continue breeding in short breeding seasons in response to predation risk but without time constraints, their response should be similar to species investing in CRS, e.g. within-season dispersal and increased nest concealment.     

A neurobiophysical interpretation of certain aspects of the problem of risks

A situation is considered in which an individual is given an opportunity to risk a certain amount of money or goods in order to gain a larger amount, providing the result of some uncertain event proves favorable. A neural mechanism is introduced in which the probability of success can be ordered according to its value. The response to a situation thus becomes dependent upon the probability. An expression is then derived for the amount that would be risked in terms of the probability and of the amount that would be gained in the event of a successful outcome. Similar expressions are obtained for the case of insurance against loss. Results of questionnaires indicate that individuals can be classified according to their pattern of behavior in the situation considered. The various types can be most easily recognized when a plot is made of the relative amount risked against the probability of success. In a general way, these types can be understood in terms of the equations derived.     

A nonlinear optimization model for fishing vessel evacuation during typhoon emergencies

We present an optimization model for fishing vessel evacuation during typhoon emergencies. Typhoon forecasts often do not accurately predict the typhoon path, so a risk assessment method is developed to evaluate the risk of fishing vessel evacuation processes. Risk assessment is the objective function of the fishing vessel evacuation optimization model. The model used is a many-to-many nonlinear assignment problem. A hybrid closed loop algorithm is used and its efficiency exceeds the traditional algorithm. The model is tested on a typhoon scenario based on harbors' distribution in Zhejiang Province, China.     

Estimating the economic impact of subclinical ketosis in dairy cattle using a dynamic stochastic simulation model

The objective of this study was to estimate the economic impact of subclinical ketosis (SCK) in dairy cows. This metabolic disorder occurs in the period around calving and is associated with an increased risk of other diseases. Therefore, SCK affects farm productivity and profitability. Estimating the economic impact of SCK may make farmers more aware of this problem, and can improve their decision-making regarding interventions to reduce SCK. We developed a dynamic stochastic simulation model that enables estimating the economic impact of SCK and related diseases (i.e. mastitis, metritis, displaced abomasum, lameness and clinical ketosis) occurring during the first 30 days after calving. This model, which was applied to a typical Dutch dairy herd, groups cows according to their parity (1 to 5+), and simulates the dynamics of SCK and related diseases, and milk production per cow during one lactation. The economic impact of SCK and related diseases resulted from a reduced milk production, discarded milk, treatment costs, costs from a prolonged calving interval and removal (culling or dying) of cows. The total costs of SCK were €130 per case per year, with a range between €39 and €348 (5 to 95 percentiles). The total costs of SCK per case per year, moreover, increased from €83 per year in parity 1 to €175 in parity 3. Most cows with SCK, however, had SCK only (61%), and costs were €58 per case per year. Total costs of SCK per case per year resulted for 36% from a prolonged calving interval, 24% from reduced milk production, 19% from treatment, 14% from discarded milk and 6% from removal. Results of the sensitivity analysis showed that the disease incidence, removal risk, relations of SCK with other diseases and prices of milk resulted in a high variation of costs of SCK. The costs of SCK, therefore, might differ per farm because of farm-specific circumstances. Improving data collection on the incidence of SCK and related diseases, and on consequences of diseases can further improve economic estimations.     

Distribution,prevalence and persistence of Cronobacter (Enterobacter sakazakii) in the nonprocessing and processing environments of five milk powder factories

Aims: To characterise the occurrence of Cronobacter in milk powder factories. Methods and Results: Cronobacter was isolated from 32% of 298 environmental samples from five factories. More isolations occurred in nonprocessing (49%) than processing areas (29%), although the greatest occurrence was in a single milk powder area during shutdown maintenance (81%) and the lowest after reinstatement of production hygiene practices (6%). Clonal analysis using PFGE placed 129 isolates into 49 groups. Most clones (45) were unique to each factory and seven were isolated in both milk powder and other areas of the same factory including tanker bays, evaporator rooms, an employee’s shoes and external roofs. Cronobacter was not isolated from raw milk processing areas. Within powder areas, 17 clones occurred at more than one and up to eight locations and six occurred more than once at the same location. Between four and seven clones were in the powder areas at each factory. The most prevalent and persistent clones were isolated from external roofs above spray driers, in air treatment areas and where high foot traffic occurs. Conclusions: Cronobacter is dispersed widely at milk powder factories. This study suggests that distribution is assisted by movement of air, milk powder and personnel and that new hygiene strategies will be needed to reduce prevalence. Significance and Impact of the Study: Knowledge of occurrence is essential for the development of strategies to control dissemination of Cronobacter within factories and reduce risk of entry into powdered milk products.     

A game dynamic model for delayer strategies in vaccinating behaviour for pediatric infectious diseases

Several studies have found that some parents delay the age at which their children receive pediatric vaccines due to perception of higher vaccine risk at the recommended age of vaccination. This has been particularly apparently during the Measles-Mumps-Rubella scare in the United Kingdom. Under a voluntary vaccination policy, vaccine coverage in certain age groups is a potentially complex interplay between vaccinating behaviour, disease dynamics, and age-specific risk factors. Here, we construct an age-structured game dynamic model, where individuals decide whether to vaccinate according to imitation dynamics depending on age-dependent disease prevalence and perceived risk of vaccination. Individuals may be timely vaccinators, delayers, or non-vaccinators. The model exhibits multiple equilibria and a broad range of possible dynamics. For certain parameter regimes, the proportion of timely vaccinators and delayers oscillate in an anti-phase fashion in response to oscillations in infection prevalence. Under an exogenous change to the perceived risk of vaccination as might occur during a vaccine scare, the model can also capture an increase in delayer strategists similar in magnitude to that observed during the Measles-Mumps-Rubella vaccine scare in the United Kingdom. Our model also shows that number of delayers steadily increases with increasing severity of the scare, whereas it saturates to specific value with increases in duration of the scare. Finally, by comparing the model dynamics with and without the option of a delayer strategy, we show that adding a third delayer strategy can have a stabilizing effect on model dynamics. In an era where individual choice—rather than accessibility—is becoming an increasingly important determinant of vaccine uptake, more infectious disease models may need to use game theory or related techniques to determine vaccine uptake.     

Assessment of thermal load on transported goats administered with ascorbic acid during the hot-dry conditions

The major factor in the induction of physiological stress during road transportation of livestock is the complex fluctuations of the thermal transport microenvironment, encountered when animals are transported across different ecological zones. Recommended guidelines on optimum “on-board” conditions in which goats should be transported are lacking, and there are no acceptable ranges and limits for the thermal loads to which goats may be subjected during long-distance road transportation in hot-dry conditions. Panting score (PS), rectal temperature (RT), heart rate (HR) and respiratory rate (RR) were employed as reliable stress indices to assess the effects of different thermal loads, measured as temperature humidity index (THI), encountered in the vehicle during 12 h of road transportation of 40 goats, and to suggest the administration of 100 mg/kg body weight of ascorbic acid (AA) as an ameliorating agent. The results obtained showed that the PS, RT, HR and RR rose above normal reference values with increase in the THI and journey duration. The rise in PS value, which is a visual indicator of the severity of thermal load, was the most pronounced. The results suggest that values of THI in the vehicle up to 94.6 constitute no risk, while at of 100 it presents a moderate risk and above 100 may result in severe stress. The relationships between the thermal load and the physiological variables were positive and significant (P < 0.05). They reflect the degree of stress imposed by each THI value during the transportation, and may be used as recommended ranges and limit thermal load values in transported goats. The results demonstrated that administration of 100 mg/kg body weight of AA before road transportation mitigated the risk of adverse effects of high THI values and other stress factors due to road transportation in goats.     

Dispersion in time and space affect mating success and Allee effects in invading gypsy moth populations

1. Understanding why invading populations sometimes fail to establish is of considerable relevance to the development of strategies for managing biological invasions. 2. Newly arriving populations tend to be sparse and are often influenced by Allee effects. Mating failure is a typical cause of Allee effects in low-density insect populations, and dispersion of individuals in space and time can exacerbate mate-location failure in invading populations. 3. Here we evaluate the relative importance of dispersal and sexual asynchrony as contributors to Allee effects in invading populations by adopting as a case study the gypsy moth (Lymantria dispar L.), an important insect defoliator for which considerable demographic information is available. 4. We used release-recapture experiments to parameterize a model that describes probabilities that males locate females along various spatial and temporal offsets between male and female adult emergence. 5. Based on these experimental results, we developed a generalized model of mating success that demonstrates the existence of an Allee threshold, below which introduced gypsy moth populations are likely to go extinct without any management intervention.     

Failure of antibiotic treatment in microbial populations

The tolerance of bacterial populations to biocidal or antibiotic treatment has been well documented in both biofilm and planktonic settings. However, there is still very little known about the mechanisms that produce this tolerance. Evidence that small, non-mutant subpopulations of bacteria are not affected by an antibiotic challenge has been accumulating and provides an attractive explanation for the failure of typical dosing protocols. Although a dosing challenge can kill the susceptible bacteria, the remaining persister cells can serve as a source of population regrowth. We give a condition for the failure of a periodic dosing protocol for a general chemostat model, which supports the simulations of an earlier, more specialized batch model. Our condition implies that the treatment protocol fails globally, in the sense that a mixed bacterial population will ultimately persist above a level that is independent of the initial composition of the population. We also give a sufficient condition for treatment success, at least for initial population compositions near the steady state of interest, corresponding to bacterial washout. Finally, we investigate how the speed at which the bacteria are wiped out depends on the duration of administration of the antibiotic. We find that this dependence is not necessarily monotone, implying that optimal dosing does not necessarily correspond to continuous administration of the antibiotic. Thus, genuine periodic protocols can be more advantageous in treating a wide variety of bacterial infections.      

阪崎肠杆菌能力验证样品均匀性和稳定性的研究

目的制备出以脱脂奶粉为基质的均匀性好、稳定性强的阪崎肠杆菌(Enterobacter sakazakii)能力验证样品。方法研究奶粉基质的粒度、奶粉和菌粉的混合比例,得到阪崎肠杆菌能力验证样品的最佳均匀性条件;研究包装形式及贮存温度对样品稳定性的影响,得到阪崎肠杆菌能力验证样品的最佳稳定性条件。结果要保证样品足够均匀,奶粉最佳粒径范围为120μmD180μm,1 g菌粉最多与300 g奶粉进行混合;贮存温度对样品稳定性有较大影响,高温明显降低样品稳定性;真空包装可以显著提高样品稳定性。结论以奶粉为基质的阪崎肠杆菌能力验证样品的制备能够更准确地考查乳品微生物检验人员的检测水平,为国内微生物能力验证水平的提高奠定了基础。     

Description and validation of a rapid (1 h) flow cytometry test for enumerating thermophilic bacteria in milk powders

AIMS: The aim of this study was to develop a rapid assay for enumerating thermophilic bacteria in milk powder. METHODS AND RESULTS: The BactiFlow flow cytometer was used to count bacteria based on esterase activity in viable bacterial cells. A protocol for total viable bacteria was modified by heat-treating the sample to selectively label thermophilic bacteria. Samples of milk powder dissolved in 0.1% peptone were treated with 0.8% ethylenediaminetetraacetic acid to reduce background interference because of denatured milk proteins. Either thermophilic bacteria were added to the dissolved milk powder or milk powder solutions were incubated at 55 degrees C for 2-3 h to enrich the natural thermophile population for testing. Results from the BactiFlow were compared with traditional plate count results. CONCLUSIONS: Thermophilic bacteria in milk powder can be enumerated within 1 h using the BactiFlow flow cytometer. SIGNIFICANCE AND IMPACT OF THE STUDY: Microbiological test results obtained within 1 h can potentially be used to monitor manufacturing processes, effectively trace problems and provide confidence in the manufacture of product.