bluuebunny/crossref_metadata_2025 huggingface dataset:
Technetium sorption by stibnite from natural water
Authors: Peretroukhine V. , Sergeant Claire , Devès G. , Poulain S. , Vesvres M. H. , Thomas B. , Simonoff M.
Published: November 2006

The sorption of technetium by powdered and polished mineral stibnite Sb2S3 has been investigated in simulated and natural underground waters from the Meuse/Haute–Marne region (France). The sorption by powdered stibnite has been found to be complete under both aerobic and anaerobic conditions in batch experiments. The sorption rate is higher in the absence of oxygen than under aerobic condition. Increasing the temperature from 30 °C to 60 °C results in a rise of the sorption rate by 9.1 and 27 times under anaerobic and aerobic conditions, respectively. The observed differences in sorption kinetics in the presence and in absence of oxygen are explained by the interaction of oxygen with sulfide ion in aerobic conditions and by the reduction of technetium(VII) by iron(II) and by other impurities present in natural water and in the mineral, and by the subsequent sorption of Tc(IV) on stibnite under anaerobic conditions. The sorption on a polished mineral surface resulted in the formation of a technetium film, probably Tc2S7, with a thickness of 1−3 μg Tc/cm2 at pH 3−6 and 4−12 μg Tc/cm2 at 9−12. The simultaneous formation of stibnite colloids with adsorbed technetium occurs at pH 9−12. The study of the technetium film on the mineral by proton induced X-ray emission analysis showed it to be at least one order of magnitude thinner on the SiO2 impurities than on the main Sb2S3 component and the iron impurities.
Mechanisms of cesium sorption onto magnetite
Authors: Granizo Noelia , Missana T.
Published: November 2006

One of the current options for the final disposal of high level radioactive wastes is the deep geological repository (DGR). The metal canisters represent the first physical barrier to radionuclide migration towards the geosphere and their corrosion products may play a significant role in sequestering radionuclides by sorption and/or (co)precipitation phenomena.

In this work, the sorption of 137Cs on pure nanocrystalline magnetite has been experimentally studied in a wide range of pH, ionic strength, and radionuclide and sorbent concentration. The magnetite was synthesized in laboratory under controlled conditions and its main physico-chemical properties as microstructure, surface area and surface charge were analysed previous to sorption experiments.

Sorption was negligible up to pH 8.5 and maximum sorption values were reached around pH 12. A significant increase in Cs sorption was observed when decreasing the ionic strength. Linear sorption isotherms were observed within the range of Cs concentration used (up to 10-6 M).

As expected, Cs showed very small sorption onto the oxide, but the whole experimental results could be satisfactorily fit with a simple model. In addition, the model developed in the oxide-electrolyte system was able to reproduce fairly well the sorption of Cs onto magnetite in two more complex waters (synthetic bentonite and cement porewaters).

All the possible effects on sorption that could increase the uncertainties on the (small) sorption values were analysed in depth. In addition, the possible influence of mineral trace impurities on the sorption (for example silicates from experimental vessels), already discussed in the literature, was avoided.
Sorption of cesium on granite under aerobic and anaerobic conditions
Authors: Lee Chuan-Pin , Lan Pei-Lun , Jan Yi-lin , Wei Yuan-Yaw , Teng Shi-Ping , Hsu Chun-Nan
Published: November 2006

This study focused on the determination of distribution coefficients (K
d) of 137Cs under aerobic (∼21% O2) and anaerobic conditions (1−10 ppm O2) which might be found in the deep geologic environment. The anaerobic conditions were simulated in a glove box filled with highly pure argon (99.9%). Both batch tests and solid-phase analyses, including X-ray diffraction, N2-BET surface area, and polar-microscopy/autoradiography were employed for analyzing the sorption of 137Cs on granite, which is the potential host rock for waste disposal in Taiwan. Before starting batch tests, the rock samples were placed in the glove box for one week, and the E
h values of experimental liquids were periodically measured until the E
h value decreased below 0 mV. The sorption of 137Cs was studied at various concentrations in synthetic groundwater. The Freundlich sorption isotherm seems to be adequate to quantitatively describe the sorption of Cs for the concentration ranges (i.e., 10-3−10-6 M) conducted in both conditions. The distribution coefficient (K) obtained from the two-week batch tests indicated no obvious difference in two systems and the values of K and n are similar. In addition, sorption onto a specific host rock was found to be dependent on its mineralogical components. The photos obtained from polar-microscopy/autoradiography analyses showed that biotite is the principal mineral component responsible for the sorption of 137Cs onto granite.
Interaction mechanisms of bacterial strains isolated from extreme habitats with uranium
Authors: Merroun Mohamed , Nedelkova M. , Rossberg Andre , Hennig C. , Selenska-Pobell Sonja
Published: November 2006

This paper summarizes the effect of pH on the speciation and cellular localization of uranium bound by bacterial strains isolated from the S15 deep-well montoring site, located at the Siberian radioactive subsurface depository Tomsk-7, Russia. Microbiological methods in combination with extended X-ray absorption fine structure (EXAFS) spectroscopy, transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDX) were applied. EXAFS analysis showed that the cells of the two isolates, Microbacterium oxydans S15-M2 and Sphingomonas sp. S15-S1, precipitate U(VI) as m-autunite-like phase at pH 4.5, probably due to the release of inorganic phosphate from the cells as result of the microbial metabolism. However, at pH 2 uranium formed complexes with organically bound phosphates of the cell surface. The results of the EXAFS studies corroborate those found using TEM and EDX analysis. Hypotheses explaining the different coordination chemistry of uranium to bacteria as a function of pH of uranium solution in terms of solubility of m-autunite and/or microbial activity are discussed.
Biotransformation of plutonium complexed with citric acid
Authors: Francis Arokiasamy J. , Dodge Cleveland J. , Gillow J. B.
Published: November 2006

The presence of organic ligands in radioactive wastes is a major concern because of their potential for increasing the transport of radionuclides from disposal sites. Biotransformation of radionuclides complexed with organic ligands should precipitate the radionuclides and retard their migration. We investigated the biotransformation of Pu(IV) (10-8to 10-5M), byPseudomonas fluorescensin the presence of excess citric acid. Analysis of242Pu-citrate by electrospray ionization-mass spectrometry (ESI-MS) indicated the presence of biligand Pucit2as the predominant complex. XANES and EXAFS analyses showed that Pu was in the +4 oxidation state and associated with citric acid as a mononuclear complex. Citric acid was metabolized byP. fluorescensat a rate of 4.9 μM/h, but in the presence of 10-8and 10-6M Pu, this rate decreased to 4.0 and 3.8 μM/h, respectively. An increase in the ionic strength of the medium from 0.18 M to 0.9 M lowered citrate metabolism by ∼65%. Pu added to the growth medium in the absence of bacteria remained as Pu(IV) in solution as a complex with citric acid. However, solvent extraction by thenoyltrifluoroacetone (TTA) and microfiltration (0.03 μm) of the medium containing bacteria after citrate biodegradation revealed the presence of polymeric Pu. The extent of formation of the Pu polymer depended on the Pu:citrate ratio, the extent of citrate metabolism, and the ionic strength of the medium.
Fish Entrainment into Irrigation Canals: An Analytical Approach and Application to the Bow River, Alberta, Canada
Authors: Post John R. , Poorten Brett T. , Rhodes Trevor , Askey Paul , Paul Andrew
Published: November 2006

The Carseland Canal on the Bow River, Alberta, diverted water at a rate of 1.4–37.7 m3/s during the 2003 irrigation season. We estimated daily entrainment rates of rainbow trout Oncorhynchus mykiss, brown trout Salmo trutta, and mountain whitefish Prosopium williamsoni throughout the diversion season using population assessments of fish in the Bow River and the irrigation canal coupled to an estimate of the evacuation rate of intentionally entrained fish. Total entrainment during the irrigation season was estimated at 3,996 rainbow trout, 664 brown trout, and 2,352 mountain whitefish. Large fish (>150 mm fork length [FL]) made up 42.0% of the total number of entrained rainbow trout, 17.0% of entrained brown trout, and 0.5% of entrained mountain whitefish, representing 1.1, 0.8, and 0.3% of the total mortality observed in these Bow River populations. Earlier estimates of canal losses based on fall rescues of fish suggest that entrainment varies annually and that the 2003 estimates were low for rainbow trout and brown trout and high for mountain whitefish. We also identified 11 additional species that were either entrained or resident in the system within the canal and associated settling pond.
Evaluation of an Unsuccessful Brook Trout Electrofishing Removal Project in a Small Rocky Mountain Stream
Authors: Meyer Kevin A. , Lamansky James A. , Schill Daniel J.
Published: November 2006

In the western United States, exotic brook trout Salvelinus fontinalis frequently have a deleterious effect on native salmonids, and biologists often attempt to remove brook trout from streams by means of electrofishing. Although the success of such projects typically is low, few studies have assessed the underlying mechanisms of failure, especially in terms of compensatory responses. A multiagency watershed advisory group (WAG) conducted a 3-year removal project to reduce brook trout and enhance native salmonids in 7.8 km of a southwestern Idaho stream. We evaluated the costs and success of their project in suppressing brook trout and looked for brook trout compensatory responses, such as decreased natural mortality, increased growth, increased fecundity at length, and earlier maturation. The total number of brook trout removed was 1,401 in 1998, 1,241 in 1999, and 890 in 2000; removal constituted an estimated 88% of the total number of brook trout in the stream in 1999 and 79% in 2000. Although abundance of age-1 and older brook trout declined slightly during and after the removals, abundance of age-0 brook trout increased 789% in the entire stream 2 years after the removals ceased. Total annual survival rate for age-2 and older brook trout did not decrease during the removals, and the removals failed to produce an increase in the abundance of native redband trout Oncorhynchus mykiss gairdneri. Lack of a meaningful decline and unchanged total mortality for older brook trout during the removals suggest that a compensatory response occurred in the brook trout population via reduced natural mortality, which offset the removal of large numbers of brook trout. Although we applaud WAG personnel for their goal of enhancing native salmonids by suppressing brook trout via electrofishing removal, we conclude that their efforts were unsuccessful and suggest that similar future projects elsewhere over such large stream lengths would be costly, quixotic enterprises.
Managing a Migratory Pest Species: A Selective Trap for Common Carp
Authors: Stuart Ivor G. , Williams Alan , McKenzie John , Holt Terry
Published: November 2006

Trapped common carp Cyprinus carpio display a pronounced escape behavior of jumping out of the water; this behavior is not exhibited by most Australian native fishes. Hence, there appears to be an important opportunity to exploit the unique jumping behavior of nonnative common carp to aid selective removal. We report on the Williams cage, a simple device that automatically separates jumping common carp from nonjumping fish. Between November 2002 and April 2005, the Williams cage was tested at Torrumbarry Weir fishway on the Murray River, Victoria, Australia, and trapped fish were counted every 24 h. The Williams cage successfully separated 88% of adult common carp into a confinement area. In contrast, more than 99.9% of 8,031 native fish passed through the Williams cage and exited the fishway. The Williams cage may provide a method for controlling dispersal and abundance of common carp and may be applicable to other nuisance fish species.
Effectiveness of a Plastic Mesh Substrate Cover for Reducing the Effects of Common Carp on Aquatic Ecosystems
Authors: Parkos Joseph J. , Santucci Victor J. , Wahl David H.
Published: November 2006

A great deal of effort has been directed at eliminating or controlling common carp Cyprinus carpio populations, but these efforts have had limited success. We assessed the effectiveness of an alternative approach, using plastic-mesh substrate covers, to reduce environmental effects of common carp, Multiple trophic levels were monitored in 0.06-ha enclosures in experimental ponds that contained either common carp with mesh covers, common carp with no mesh covers, no common carp with mesh covers, or neither fish nor mesh covers. Macroinvertebrates and macrophytes were also sampled over a 1-year period in six field sites with paired mesh cover and control plots. Common carp significantly increased turbidity (NTU) and total phosphorus (μg/L), decreased macrophyte cover (%), altered the relative abundance of zooplankton taxa (N/L), and suppressed macroinvertebrate abundance (N/m2) in ponds. In contrast, carp did not significantly affect either total nitrogen (μg/L) or phytoplankton (μg/L) concentrations. Mesh substrate covers did not significantly reduce any effects of common carp in the pond enclosures. Abundances of macroinvertebrates and macrophytes also did not differ between field plots with and without mesh covers. The lack of effective reduction of common carp-induced effects limits the usefulness of mesh substrate covers as a tool for habitat restoration.
Diet and Bioenergetics of Lake‐Rearing Juvenile Chinook Salmon in Lake Washington
Authors: Koehler Michele E. , Fresh Kurt L. , Beauchamp David A. , Cordell Jeffery R. , Simenstad Charles A. , Seiler David E.
Published: November 2006

Use of lake habitats by ocean‐type Chinook salmonOncorhynchus tshawytschais rare under natural conditions. We studied aspects of the trophic ecology of naturally and hatchery‐produced juvenile Chinook salmon rearing in the littoral zone of highly urbanized Lake Washington in Washington State. During February through May, naturally produced juvenile Chinook salmon occupied littoral habitats and consumed mostly epibenthic prey, primarily chironomid pupae (Diptera). In June, they switched to a diet dominated by plankton, specificallyDaphniaspp. This diet shift from littoral prey to limnetic prey coincided with increasing temperature, a shift by the fish from littoral to limnetic habitats, the spring bloom ofDaphnia, and increasing fish size. Bioenergetics modeling for these populations estimated that naturally produced juvenile Chinook salmon had high consumption rates and were generally feeding close to their maximum ration, even after large numbers of hatchery‐produced Chinook salmon entered the lake. The feeding rates, growth rates, and proportions of maximum daily ration from the modeling suggested that under current conditions, both naturally produced and hatchery‐produced juvenile Chinook salmon were finding ample food in littoral habitats of Lake Washington. These results further reveal that hatchery‐produced Chinook salmon did not compete with naturally produced fish and that this was probably a result of hatchery juveniles entering the lake during the springDaphniabloom when this prey is abundant. Our results suggest that managers should focus Chinook salmon recovery efforts in the Lake Washington basin on other aspects of the species' lake use, such as predation or disease, or on other life stages (e.g., spawning adults).
Poststocking Movements and Habitat Use of Hatchery‐Reared Juvenile Pallid Sturgeon in the Missouri River below Fort Randall Dam, South Dakota and Nebraska
Authors: Jordan George R. , Klumb Robert A. , Wanner Greg A. , Stancill Wayne J.
Published: November 2006

Telemetry was used to evaluate seasonal and diel movement patterns, general habitat use, survival, and spatial distributions of hatchery‐reared juvenile pallid sturgeon Scaphirhynchus albus stocked in the Missouri River below Fort Randall Dam, South Dakota and Nebraska. Sampling occurred at about 2‐week intervals during spring through fall. Of 22 ultrasonically tagged fish, 13 were intensively followed to assess hourly diel movement rates. A total of 258 relocations were made for the 22 tagged fish; 19 fish were relocated at least once, and 16 were relocated multiple times. At least 68% of tagged fish survived for 2.5 years. In 2000, fish were found mainly upstream of the stocking site, whereas in 2001 and 2002 the entire reach was used. Juveniles were found primarily in the main channel at depths exceeding 80% of the maximum channel cross‐section depth, where bottom current velocities ranged from 0.1 to 0.9 m/s. Clusters of juvenile pallid sturgeon (i.e., two or more fish) within 750 m of each other were observed on 15 dates, and clusters of juveniles within 500 m of each other were observed on 10 dates. Clusters were observed during all seasons. Mean (±2 SE) range of movement was significantly less in 2000 (8.3 ± 5.8 km) than in 2001 (29.3 ± 8.8 km) and 2002 (28.9 ± 15.0 km). We detected no significant differences in movement rates among years, seasons, or diel periods (i.e., dawn, daytime, dusk, and night). Our study indicates that range of movements of juvenile pallid sturgeon based on shorter studies (i.e., ≤1 year) should be interpreted cautiously because hatchery‐reared fish may not have acclimated to the riverine environment until the second year after stocking. Based on survival and distribution of juvenile pallid sturgeon throughout the study area, we conclude that this reach is suitable for recovery efforts.
Effect of Discharge on Daytime Habitat Use and Selection by Muskellunge in the New River, Virginia
Authors: Brenden Travis O. , Murphy Brian R. , Hallerman Eric M.
Published: November 2006

For several fish species, increased river discharge has been linked to behavioral changes, including movement towards particular habitats. From 2000 to 2003, we used radiotelemetry to monitor habitat use by 42 muskellunge Esox masquinongy within a 17‐km reach of the New River, Virginia; to evaluate habitat selection; and to determine whether habitat use and selection were affected by discharge. Water depth, occurrence of aquatic vegetation, substrate type, and distance to riverbanks within the study reach were mapped with hydroacoustic and Global Positioning System technologies. Real‐time discharge measurements from an upstream U.S. Geological Survey stream gauge were used to classify fish locations into those made during periods of reduced (<75 m3/s) or increased (>75 m3/s) discharge. Seasonal habitat selection models for the different discharge levels were created using logistic regression. Differences in logistic regression coefficients between models were tested with multivariate chi‐square tests and Bonferroni‐corrected pairwise comparisons. Meta‐analytic averaging of Pearson's correlation coefficients was used to determine the overall effect size of discharge on habitat use by muskellunge. Overall, muskellunge exhibited a positive selection for deeper habitats; however, discharge was found to significantly affect both habitat use and selection. Habitat use was consistent with the hypothesis that fish moved to shallower habitats (both summer and winter) located closer to riverbanks (winter only) during periods of increased discharge. In terms of habitat selection, selection strengths for variables such as water depth (summer and winter) and distance to shoreline (winter only) generally weakened during periods of increased discharge, indicating that habitat use became more proportionate to availability. Increased movement as a result of increased discharge has been theorized to potentially reduce winter survival of fish because of seasonal energetic limitations. Thus, indirect effects on fish from dam operating modes (e.g., hydropeaking) may be as important as direct effects when evaluating biotic implications of water release schedules.
A Bioenergetics‐Based Approach to Explain Largemouth Bass Size in Tropical Reservoirs
Authors: Neal J. Wesley , Noble Richard L.
Published: November 2006

In tropical systems where largemouth bass Micropterus salmoides have been introduced, maximum age is reduced to the point where few fish live beyond 3 years and adult growth rates are very slow. Concurrently, tropical largemouth bass have an extended spawning period (up to 8 months) and individual fish spawn multiple times each year. In this study, we examined the relationship between latitude and maximum size (record angler‐caught fish) of largemouth bass from temperate to tropical environments and tested the hypothesis that the slow growth of adult largemouth bass is the result of excessive energy reallocation to reproduction. State and national record‐sized largemouth bass were plotted against latitude for the USA, Cuba, Dominican Republic, Japan, Portugal (European record), Mexico, and Puerto Rico. Largemouth bass maximum weight increased as latitude decreased from 46.8°N; peak maximum weight occurred at 27.9°N. Below 27.9°N, largemouth bass size records decreased as latitude decreased (R2 = 0.67, P < 0.0001). Bioenergetics models were used to model observed growth (in Puerto Rico) and predicted growth based on a 2% mean daily ration (MDR), and reproduction scenarios were used to explain the difference between observed and predicted growth. The predicted weight in Puerto Rico was 2.7 times higher than observed weight during a simulated 6‐month spawning season. This discrepancy could be accounted for by a range of spawning frequencies (events per season) and levels (percent body weight per spawn) for females (e.g., 10 spawns at 6% body weight per spawn). Similarly, a 15% decrease in MDR of nest‐guarding males due to reduced ability to feed accounted for the difference between predicted and observed growth.
Tag Return Estimation of Annual and Semiannual Survival Rates of Adult Female Blue Crabs
Authors: Lambert Debra M. , Hoenig John M. , Lipcius Romuald N.
Published: November 2006

Stock status of the blue crab Callinectes sapidus in Chesapeake Bay is determined by comparing current estimates of fishing mortality with biological reference points. Given the recent focus on blue crab conservation, there is a need to obtain reliable estimates of survival to compare with the biological reference points. A tagging program was initiated on the terminally molted, mature female component of the Chesapeake Bay blue crab stock to estimate annual and semiannual survival rates. Crabs were obtained from fishery‐independent research surveys throughout the bay and were measured, tagged, and released on‐site. Tagging was conducted twice per year (winter and summer) from November 2001 to March 2005. Annual survival and tag recovery rates were estimated independently for the winter and summer tagging data using Brownie models. The two independent estimates of annual survival based on winter tagging (mean ± SE = 0.081 ± 0.031) and summer tagging (0.080 ± 0.024) data were virtually identical and low. The estimated tag recovery rate was 24% based on winter tagging data and 17% based on summer tagging data. The estimated monthly survival rate during winter (mean ± SE = 0.868 ± 0.016) was higher than that during summer (0.748 ± 0.019). The low estimates of annual survival are consistent with (1) historical estimates of the percentage of age‐2 and older females in the winter dredge fishery, and (2) recent estimates of exploitation rate obtained from the ratio of catch to initial abundance. These findings indicate that survival rates of mature female blue crabs in Chesapeake Bay have remained extremely low during a period of depressed abundance, which may be preventing stock recovery. Moreover, this study represents one of the few to derive experimental Brownie model estimates of semiannual survival of an invertebrate species subject to a continuous fishery.
Theoretical treatment of crowd–structure interaction dynamics
Authors: Alexander N. A.
Published: November 2006

The equations governing crowd–structure interaction dynamics are derived from first principles. No assumptions are made about structural support conditions, crowd or beam displacements or crowd-induced forces in this derivation. The general equations of motion are shown to exist in pairs of two-degrees-of-freedom systems, for every ith beam–crowd mode. Numerical optimisation of the system response functions is preferred to both classical undamped eigenvalue analysis and a damped complex eigenvalue analysis using a state space formulation. Single parameter continuation of optima of frequency response functions is employed. In addition, two parameter continuations of folds of these optima are used. As a result, a fold loci plot in parameter space defines the region where multiple beam optima exist. This results in the possibility of complicated response behaviour. Increases in predominant frequency of the structure with increasing crowd mass are observed. In other cases, sudden drops in predominant frequency with increasing crowd mass are observed.
New algorithm for fixed-angle softened-truss model
Authors: Lee J.-Y. , Mansour M. Y.
Published: November 2006

The present paper proposes a solution methodology to predict the shear stress–shear strain curves of reinforced concrete (RC) elements (panels) using a truss model. The proposed solution procedure calculates the concrete constitutive relationships by transforming the concrete stresses and strains from the principal direction of concrete stresses to the principal direction of the applied stresses. As a result, the algorithm predicts the shear responses of RC elements having a large difference between the amounts of steel in two perpendicular directions. To check the success of the proposed methodology, the experimental shear stress–strain and shear stress–normal strain curves of 12 RC elements as well as the shear strengths of 170 beams reported in the literature are compared with their corresponding predicted results using the new algorithm of the truss model. The results show that the proposed algorithm accurately predicts the variation of the concrete strain of 12 reinforced elements and the shear strength of 170 beams.
A Note on Credit Insurance
Authors: Leitner Johannes
Published: November 2006

In a simple stationary setting with constant interest rate, we derive pricing formulas for defaultable bonds with stochastic recovery rate using a replication argument. Replication is done by using an insurance contract (i.e. a kind of credit default swap), the price of which is determined by a dynamic premium calculation principle. We consider two cases, a linear one, where pricing amounts to solving an inhomogeneous linear ODE, and a super-linear case where a Riccati ODE has to be solved.
On the Tail Behavior of Sums of Dependent Risks
Authors: Barbe Philippe , Fougères Anne-Laure , Genest Christian
Published: November 2006

The tail behavior of sums of dependent risks was considered by Wüthrich (2003) and by Alink et al. (2004, 2005) in the case where the variables are exchangeable and connected through an Archimedean copula model. It is shown here how their result can be extended to a broader class of dependence structures using multivariate extreme-value theory. An explicit form is given for the asymptotic probability of extremal events, and the behavior of the latter is studied as a function of the indices of regular variation of both the copula and the common distribution of the risks.
Marginal Decomposition of Risk Measures
Authors: Venter Gary G. , Major John A. , Kreps Rodney E.
Published: November 2006

The marginal approach to risk and return analysis compares the marginal return from a business decision to the marginal risk imposed. Allocation distributes the total company risk to business units and compares the profit/risk ratio of the units. These approaches coincide when the allocation actually assigns the marginal risk to each business unit, i.e., when the marginal impacts add up to the total risk measure. This is possible for one class of risk measures (scalable measures) under the assumption of homogeneous growth and by a subclass (transformed probability measures) otherwise. For homogeneous growth, the allocation of scalable measures can be accomplished by the directional derivative. The first well known additive marginal allocations were the Myers-Read method from Myers and Read (2001) and co-Tail Value at Risk, discussed in Tasche (2000). Now we see that there are many others, which allows the choice of risk measure to be based on economic meaning rather than the availability of an allocation method. We prefer the term “decomposition” to “allocation” here because of the use of the method of co-measures, which quantifies the component composition of a risk measure rather than allocating it proportionally to something.

Risk adjusted profitability calculations that do not rely on capital allocation still may involve decomposition of risk measures. Such a case is discussed. Calculation issues for directional derivatives are also explored.
A Damaged Generalised Poisson Model and its Application to Reported and Unreported Accident Counts
Authors: Scollnik David P.M.
Published: November 2006

This paper investigates some models in which non-negative observations from a Poisson or generalised Poisson distribution are possibly damaged according to a binomial or quasi-binomial law. The latter case is appropriate when the observations are over-dispersed. Although the extent of the damage is not known, it is assumed that the event of whether or not damage occurred is discernible. The models are particularly suited for certain applications involving accident counts when evidence of certain accidents may be observed even though the accidents themselves may go unreported. Given the number of observed accidents and knowledge as to whether or not some additional accidents have gone unreported, these models may be used to make inferences concerning the actual number of unreported and total number of accidents in the current period, and the numbers of reported, unreported, and/or total accidents in a future period. The models are applied to a real data set giving reported and unreported patient accidents in a large hospital. Both maximum likelihood and Bayesian estimation methods are presented and discussed.
A Note on the Dividends-Penalty Identity and the Optimal Dividend Barrier
Authors: Gerber Hans U. , Lin X. Sheldon , Yang Hailiang
Published: November 2006

For a general class of risk models, the dividends-penalty identity is derived by probabilistic reasoning. This identity is the key for understanding and determining the optimal dividend barrier, which maximizes the difference between the expected present value of all dividends until ruin and the expected discounted value of a penalty at ruin (which is typically a function of the deficit at ruin). As an illustration, the optimal barrier is calculated in two classical models, for different penalty functions and a variety of parameter values.
The Mean Square Error of Prediction in the Chain Ladder Reserving Method (Mack and Murphy Revisited)
Authors: Buchwalder Markus , Bühlmann Hans , Merz Michael , Wüthrich Mario V.
Published: November 2006

We revisit the famous Mack formula [2], which gives an estimate for the mean square error of prediction MSEP of the chain ladder claims reserving method: We define a time series model for the chain ladder method. In this time series framework we give an approach for the estimation of the conditional MSEP. It turns out that our approach leads to results that differ from the Mack formula. But we also see that our derivation leads to the same formulas for the MSEP estimate as the ones given in Murphy [4]. We discuss the differences and similarities of these derivations.
Life Annuitization: Why and how Much?
Authors: Hainaut Donatien , Devolder Pierre
Published: November 2006

This paper addresses some of the problems a majority of retired individuals face: Why and in what proportion should they invest in a life annuity to maximize the utility of their future consumption or a bequest? The market considered in this work is made up of three assets: a life annuity, a risky asset and a cash account. As this problem doesn’t accept any suitable explicit solution, it is numerically solved by the Markov Chain approximation developed by Kushner and Dupuis. Without a bequest motive, we observe that the optimal planning of consumption is divided into two periods and that optimal asset allocation should include the risky asset. Next, the influence of a bequest on consumption and investment pattern is developed. We demonstrate that even with a bequest motive, pensioners should allocate a part of their wealth to the purchase of life annuities.
The Estimation Error in the Chain-Ladder Reserving Method: A Bayesian Approach
Authors: Gisler Alois
Published: November 2006

We derive the estimation error in a Bayesian framework and discuss the estimates of Mack and of Buchwalder, Bühlmann, Merz and Wüthrich (BBMW) from a Bayesian point of view.
In vivo protective performance of N95 respirator and surgical facemask
Authors: Li Y. , Wong T. , Chung J. , Guo Y.P. , Hu J.Y. , Guan Y.T. , Yao L. , Song Q.W. , Newton E.
Published: November 2006

Background

The SARS outbreak in 2003 has spawned a major controversy concerning protective performance facemasks for healthcare workers. This study reports a study on in‐vivo protective performance of surgical masks and N95 respirators.

Methods

Typical surgical masks and N95 respirators used in Hong Kong hospitals were tested in comparison with those treated with nano‐functional materials (called nano‐masks) on various physical properties and in‐vivo wear filtration efficiency, as well as usability test in hospitals for surgical masks.

Results

Tests on physical properties showed that N95 respirators had significantly lower air permeability and water vapor permeability than surgical masks. The in‐vivo filtration tests illustrated that N95 respirators filtered out 97% of potassium chloride (KCl) solution, while surgical masks filtered out 95% of KCl solution. Nano‐masks show stronger water repellency and antibacterial activities, but no difference in usability, comparing with normal N95 and surgical masks.

Conclusions

Surgical masks can provide in‐vivo filtration protection of 95% filtration efficiency. N95 respirators provide higher in‐vivo filtration efficiency of 97% with significant reduction of air permeability and water vapor permeability. Compared to normal surgical masks/respirators, the nano‐masks can provide additional protective functions in stopping capillary diffusion and antibacterial activities. Am. J. Ind. Med. 2006. © 2006 Wiley‐Liss, Inc.
Smoking behavior in trucking industry workers
Authors: Jain Nitin B. , Hart Jaime E. , Smith Thomas J. , Garshick Eric , Laden Francine
Published: November 2006

Background

In retrospective occupational studies, the degree of confounding by smoking depends on variation in smoking among job‐related exposure groups. We assessed the relationship between job title and smoking behavior as part of a study on occupational exposures and lung cancer.

Methods

A questionnaire on smoking was mailed to a sample of 11,986 trucking industry workers. Company records were used to gather other relevant information.

Results

The response rate was 40.5%. Among white males, the age‐adjusted prevalence of ever smoking was highest among longhaul truck drivers (67%) and lowest among clerks (44%). Smoking rates among workers with other job titles were similar.

Conclusions

Our results will be used to adjust for the differences in smoking among job‐related exposure groups when assessing the association between particulate matter exposure and lung cancer mortality. Our study also suggests that an assessment of methods to control for smoking should be considered in the design of retrospective occupational health studies. Am. J. Ind. Med. 2006. © 2006 Wiley‐Liss, Inc.
Twenty‐three years of hypersensitivity pneumonitis mortality surveillance in the United States
Authors: Bang Ki Moon , Weissman David N. , Pinheiro Germania A. , Antao Vinicius C.S. , Wood John M. , Syamlal Girija
Published: November 2006

Background

There are few population‐based studies addressing hypersensitivity pneumonitis (HP) in the United States. The National Institute for Occupational Safety and Health (NIOSH) has nationally comprehensive longitudinal mortality data that can contribute to a better understanding of the epidemiology of HP.

Methods

The National Center for Health Statistics multiple cause‐of‐death data were analyzed for the period 1980–2002. Annual death rate was age‐adjusted to the 2000 U.S. standard population. Death rate time‐trends were calculated using a linear regression model and geographic distribution of death rates were mapped by state and county. Proportionate mortality ratios (PMRs) by usual industry and occupation adjusted for age, sex, and race, were based on data from 26 states reporting industry and occupation during 1985–1999.

Results

Overall age‐adjusted death rates increased significantly (P < 0.0001) between 1980 and 2002, from 0.09 to 0.29 per million. Wisconsin had the highest rate at 1.04 per million. Among industries, PMR for HP was significantly high for agricultural production, livestock (PMR, 19.3; 95% CI, 14.0–25.9) and agricultural production, crops (PMR, 4.3; 95% CI, 3.0–6.0). Among occupations, PMR for HP was significantly elevated for farmers, except horticulture (PMR, 8.1; 95% CI, 6.4–10.2).

Conclusions

These findings indicate that agricultural industries are closely associated with HP mortality and preventive strategies are needed to protect workers in these industries. Am. J. Ind. Med. 2006. © 2006 Wiley‐Liss, Inc.
Neurobehavioral functioning after cessation of manganese exposure: A follow‐up after 14 years
Authors: Bouchard M. , Mergler D. , Baldwin M. , Panisset M. , Bowler R. , Roels H.A.
Published: November 2006

Background

Little is known on the long‐term course of early manganese (Mn) neurotoxic effects. Mn alloy workers were examined in a follow‐up study 14 years after exposure ceased at a Canadian facility.

Methods

The same battery of neurofunctional tests used in the initial examination in 1990 was administered to 77 Mn‐workers and 81 referents in 2004.

Results

Manganese‐workers had poorer scores compared to referents both in the initial and follow‐up examinations for several motor tasks of the Luria Motor Scale. At follow‐up, older Mn‐workers (>45 years at cessation of exposure) had poorer scores than referents for tests of cognitive flexibility. Cumulated exposure was associated with poorer test scores for certain neuromotor and cognitive tests and on a mood scale. Differences on certain tests observed at initial examination were not present at follow‐up.

Conclusions

Manganese exposure was associated with persistent deficits for certain neuromotor functions, cognitive flexibility, and adVerse mood states, while recovery occurred for other functions. Am. J. Ind. Med. 50:831–840, 2007. © 2007 Wiley‐Liss, Inc.
Industrial sectors with high risk of women's hospital‐treated injuries
Authors: Kines Pete , Hannerz Harald , Mikkelsen Kim Lyngby , Tüchsen Finn
Published: November 2006

Background

Women's occupational injury rates are converging with those of males. Associations between female workers' hospital treated injury rates, industrial sector and injured body area were analyzed to provide for better‐focused injury prevention of women's hazardous jobs.

Methods

Females' standardized hospital treatment ratios (SHR) and the excess fraction for five body regions (head/neck, thorax, back, upper and lower extremities) were calculated for 58 industrial sectors for 1999–2003.

Results

Five industrial sectors, “Cleaning, laundries and dry cleaners,” “Transport of passengers,” “Hotels and restaurants,” “Hospitals” and “Transport of goods” had significantly high SHRs for all five body regions. The excess fraction for upper extremity injuries revealed that 14%–27% of injuries could theoretically have been avoided.

Conclusions

There is strong evidence for an association between women's hospital treated injuries and industrial sector. The results justify the need for gender‐sensitive analyses to orient injury prevention programs. Am. J. Ind. Med. 50:13–21, 2007. © 2006 Wiley‐Liss, Inc.
Pervaporation separation of water/isopropanol mixtures through crosslinked carboxymethyl chitosan/polysulfone hollow‐fiber composite membranes
Authors: Shen Jiang‐nan , Wu Li‐guang , Qiu Jun‐hong , Gao Cong‐jie
Published: November 2006

Carboxymethyl chitosan (CMCS)/polysulfone (PS) hollow‐fiber composite membranes were prepared through glutaraldehyde (GA) as the crosslinking agent and PS hollow‐fiber ultrafiltration membrane as the support. The permeation and separation characteristics for dehydration of isopropanol were investigated by the pervaporation method. Pure chitosan, carboxymethyl chitosan, and crosslinked carboxymethyl chitosan membranes were characterized by Fourier transform infrared (FT‐IR) spectroscopy and X‐ray diffraction (XRD) to study the crosslinking reaction mechanism and degree of crystallinity, respectively. The effects of feed composition, crosslinking agent, membrane thickness, and feed temperature on membrane performance were investigated. The results show that the crosslinked CMCS/PS hollow‐fiber composite membranes possess high selectivity and promising permeability. The permeation flux and separation factor for isopropanol/water is 38.6 g/m2h and 3238.5, using 87.5 wt % isopropanol concentration at 45°C, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1959–1965, 2007
Synthesis and characterization of conducting polyaniline‐activated carbon nanocomposites
Authors: Karim Mohammad Rezaul , Lee Chul Jae , Lee Mu Sang
Published: November 2006

Conducting polyaniline (PAni)/activated carbon (AC) nanocomposites were synthesized by the in situ chemical polymerization method. The resultant shell–core PAni–AC nanocomposites were characterized by elemental analysis, Fourier transform infrared, scanning electron microscopy, thermal gravimetric analysis, X‐ray diffraction, and transmission electron microscopy. We did not observe any significant chemical interaction between the PAni and AC, only core–shell coupling between the AC and the tightly coated polymer chain was revealed. Measurement of the physical properties showed that the incorporation of conducting PAni on to AC particles during chemical synthesis increased electrical conductivity and thermal stability by several orders of magnitude to that of the pristine PAni powders. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1973–1977, 2007
Synthesis and properties of new polyamides based on a hydroxyethyl cinnamide extended from 3,5‐diaminobenzoic acid
Authors: Onciu Marioara
Published: November 2006

A series of new aromatic polyamides containing cinnamide pendent units were prepared from 2′‐(cinnamide)ethyl‐3,5‐diaminobenzoate and various aromatic dicarboxylic acids by the direct polycondensation reaction, with triphenyl phosphite and pyridine as condensing agents. The polyamides were characterized by 1H NMR, IR, and UV spectroscopy, and gel permeation chromatography. Their thermal stability was studied by thermogravimetric analysis in air, and differential scanning calorimetry. These polymers were readily soluble in polar aprotic solvents and can be cast from their solutions in flexible and tough films. Glass transition temperatures (Tgs) of these polyamides were observed in the range of 225–245°C. Their inherent viscosities varied from 0.77 to 1.12 dL/g that corresponded to weight–average and number–average molecular weights of 39,000–72,700 and 18,800–29,000, respectively. These polymers can be photochemically crosslinked. The photochemical aspects were revealed by means of UV–vis and IR analyses onto thin films. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2013–2020, 2007
Influence of incorporating CaCO3 into room temperature vulcanized silicone sealant on its mechanical and dynamic rheological properties
Authors: Xu Xiaoming , Song Yihu , Zheng Qiang , Hu Guohua
Published: November 2006

Silicone sealants with low modulus and high elongation were prepared by using ketoxime silane as chain extender agent, and a novel silane coupling agent acting as adhesion promoting agent was synthesized. Mechanical properties of vulcanized polydimethylsiloxane (PDMS) filled with large amounts of carbonate calcium (CaCO3) and dynamic viscoelastic properties of unvulcanized samples were investigated through electronic multifunctional tensile tests, dynamic mechanical analyzers, and dynamic rheological measurements. The results of mechanical tests indicate that diminishing the particle diameter size, narrowing the particle diameter distribution, and increasing the filler amount lead to a relative high tensile strength and modulus at 100% elongation, but a relative low elongation at break. The reasons for these are believed to be the evolution of molecular interactions and the formation of additional physical crosslinking induced by the filler network. Compared to virgin PDMS, there is a significant elevation of glass transition temperature with filler addition. On the other hand, the results of dynamic rheological measurements reveal that as filler amount increases, the span of the linear viscoelastic region in which dynamic storage modulus (G′) is constant in low strain amplitude narrows. However, a characteristic plateau phenomenon appears in low frequency regions together with increasing the width and height of the modulus plateau. This phenomenon is also ascribed to the formation of a filler network due to filler–polymer and filler–filler interaction. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2027–2035, 2007
Acrylonitrile content as a predictor of the captan permeation resistance for disposablenitrile rubber gloves
Authors: Phalen R. N. , Hee S. S. Que , Xu W. , Wong W. K.
Published: November 2006

The aim of this study was to determine whether the acrylonitrile (ACN) content influences the permeation resistance of disposable nitrile rubber (NBR) gloves to aqueous solutions of the pesticide captan. Attenuated total reflectance/Fourier transform infrared (ATR–FTIR) spectrophotometry at 2237 ± 5 cm−1 was used to measure the ACN contents of seven different NBR gloves. The ACN contents of the gloves ranged from 12.7 to 29.9%. Permeation was conducted according to American Society for Testing and Materials (ASTM) Method F 739‐99a with a gas chromatography/mass spectrometry analysis of captan in the hexane collection liquid. Significant correlations were found between (1) the ACN content and mass‐to‐area ratio and the logarithm of the steady‐state permeation rate (SSPR; Pearson correlation coefficient = 0.9227, p ≤ 0.05), and (2) the ACN content and mass‐to‐area ratio and the ASTM normalized breakthrough detection time (NBT) at 0.25 μg/cm2 (Pearson correlation coefficient = 0.9471, p ≤ 0.05). On average, the NBT increased 120 min for every 5% increase in the ACN content. The average SSPR ranged from 0.002 to 0.40 μg/cm2/min, a 200‐fold difference. Increasing the ACN content resulted in decreased SSPR. ATR–FTIR was useful in determining the NBR polymer ACN content, surface homogeneity, and potential glove chemical resistance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2057–2063, 2007