bluuebunny/crossref_metadata_2025 huggingface dataset:
Classic adsorption isotherms incorporated in modern surface complexation models: Implications for sorption of actinides
Authors: Kulik Dimitrii A.
Published: November 2006

Computer-aided surface complexation models (SCMs) are widely used in describing mineral-water interface reactions such as sorption of actinides onto (hydr)oxides and clays. Most SCMs are built upon balances of surface binding sites. In fact, such models can reproduce only competitive Langmuir isotherms, plus optional electrostatic corrections. Hence, it may be difficult to extend such SCMs to some real-surface phenomena (site heterogeneity, lateral interactions, surface precipitation) described in isotherms other than Langmuir. In this contribution, a new approach to overcome this difficulty is presented which does not use surface site balances, is not restricted only to Langmuir isotherms, and can be implemented within the Gibbs energy minimization solvers of chemical (adsorption) equilibria. It is suggested to define the ideal behavior of a surface species using a linear isotherm only. Conversely, an adsorption isotherm equation of choice can be split into a linear term (involving the standard-state density and the equilibrium constant referenced to infinite dilution) and a non-linear surface activity coefficient term (SACT, involving the site density parameter). A simple method is proposed for deriving a SACT for the monodentate surface binding from the Langmuir isotherm. This method is then applied to obtain SACTs for mono-, bi-, tri- and tetra-dentate binding from the “quasi-chemical approximation” isotherm, as well as a SACT accounting for non-ideal lateral interactions between surface species from the Frumkin isotherm. The new approach is illustrated by modeling UVI adsorption on goethite at ambient conditions using a GEM SCM. It is shown that SACTs are useful at moderate- to high surface coverage, but only when the site density parameter is fixed from independent (crystallographic) data and not adjusted to fit the titration data. Ways to enhance SCMs with BET, Freundlich and other isotherms of interest for retention of actinides and fission products on mineral surfaces are also discussed.
Use of thermodynamic sorption models to derive radionuclide K
d values for performance assessment: selected results and recommendations of the NEA sorption project
Authors: Ochs Michael , Davis James A. , Olin Markus , Payne Timothy E. , Tweed Cherry J. , Askarieh M. M. , Altmann S.
Published: November 2006

For the safe final disposal and/or long-term storage of radioactive wastes, deep or near-surface underground repositories are being considered world-wide. A central safety feature is the prevention, or sufficient retardation, of radionuclide (RN) migration to the biosphere. To this end, radionuclide sorption is one of the most important processes. Decreasing the uncertainty in radionuclide sorption may contribute significantly to reducing the overall uncertainty of a performance assessment (PA).

For PA, sorption is typically characterised by distribution coefficients (K
d values). The conditional nature of K
d requires different estimates of this parameter for each set of geochemical conditions of potential relevance in a RN´s migration pathway. As it is not feasible to measure sorption for every set of conditions, the derivation of K
d for PA must rely on data derived from representative model systems. As a result, uncertainty in K
d is largely caused by the need to derive values for conditions not explicitly addressed in experiments.

The recently concluded NEA Sorption Project [1] showed that thermodynamic sorption models (TSMs) are uniquely suited to derive K
d as a function of conditions, because they allow a direct coupling of sorption with variable solution chemistry and mineralogy in a thermodynamic framework. The results of the project enable assessment of the suitability of various TSM approaches for PA-relevant applications as well as of the potential and limitations of TSMs to model RN sorption in complex systems.
Modeling spent nuclear fuel alteration and radionuclide migration in disposal conditions
Authors: Windt Laurent de , Schneider H. , Ferry C. , Catalette H. , Lagneau V. , Poinssot C. , Poulesquen A. , Jegou Christophe
Published: November 2006

A physico-chemical model developed for spent fuel alteration was integrated in a global reactive transport model of a spent fuel disposal system, considering both decaying and stable isotopes, corroded steel canisters, bentonite backfills and a clayey host-rock. Fuel evolution took into account radiolytic-enhanced corrosion and long-term solubility-controlled dissolution as well as instantaneous release fractions. The calculations show that spent-fuel dissolution has no significant alteration effect on the near-field components except an oxidizing plume in the vicinity of the waste packages. The dissolved uranyl species, partly precipitate as schoepite on the fuel pellets, and partly diffuse in the near-field where magnetite and pyrite reduce U(VI) to yield uraninite precipitation. Under disposal conditions, preliminary calculations indicate that steel corrosion may generate sufficient dissolved hydrogen as to react with radiolytic oxidants and inhibit fuel dissolution. The formation of a protective schoepite layer could also reduce the alteration of fuel pellets. Radionuclides migration (Am, Cs, I) in the near-field is discussed in a second stage discriminating between sorption, precipitation and radioactive decay processes. The migration of Cs is translated in terms of cumulative activity profiles useful for integrated performance assessment.
Evaluation of the Recovery Period in Mark–Recapture Population Estimates of Rainbow Trout in Small Streams
Authors: Temple Gabriel M. , Pearsons Todd N.
Published: November 2006

We compared the backpack electrofishing capture efficiencies and Petersen-type mark–recapture abundance estimates of resident rainbow trout Oncorhynchus mykiss that had recovered for 24 h versus 3 h after electrofishing, handling, marking, and release in thirteen 100-m sites in four Yakima River basin tributary streams in central Washington State. Our results indicate that the catchability of rainbow trout was not significantly different between the two recovery periods (P = 0.27). Similarly, Petersen-type mark–recapture abundance estimates did not differ between the two recovery periods (P = 0.20). Despite vigilant effort at installing and maintaining block nets during the 24-h period, we detected fish movement out of 75% of our sites. In addition, our block nets collapsed or were destroyed by small animals in 36% of sites used for a 24-h recovery period; therefore, valid estimates could not be calculated. In contrast, no movement or net failure was detected during the 3-h recovery period. Some of the advantages of a 3-h recovery period between mark–recapture backpack electrofishing events include (1) increased probability of generating a population estimate because of a low threat of block-net failure; (2) lower probability of violating the movement assumption associated with the Petersen-type mark–recapture estimator; and (3) completion of field sampling within a single site visit on a single day. We believe that these advantages should be considered when designing sampling protocols for enumerating stream fish populations.
Mitochondrial DNA Variation in the Endangered Colorado Pikeminnow: A Comparison among Hatchery Stocks and Historic Specimens
Authors: Borley Kimberly , White Matthew M.
Published: November 2006

The Colorado pikeminnow Ptychocheilus lucius is a federally endangered species restricted to the Colorado River. Dexter National Fish Hatchery and Technology Center, Dexter, New Mexico, maintains three separate captive stocks of the Colorado pikeminnow: 1974YC (Yampa River), 1981YC (Green–Colorado rivers), and 1991YC (Colorado River). We surveyed mitochondrial DNA diversity in these three stocks (879 base pairs [bp]; ND-4L and ND-4 genes; N = 30) and in museum specimens collected from 1890 to 1976 (450 bp; ND-4; N = 11). All individuals had the same haplotype except for a 1-bp variant detected in 2 of the 12 fish from 1981YC. The low variation is postulated to be the result of a post-Pleistocene bottleneck in the wild and small sizes of the hatchery founder populations.
Predicted Changes in Subyearling Fall Chinook Salmon Rearing and Migratory Habitat under Two Drawdown Scenarios for John Day Reservoir, Columbia River
Authors: Tiffan Kenneth F. , Garland Rodney D. , Rondorf Dennis W.
Published: November 2006

We evaluated the potential effects of two different drawdown scenarios on rearing and migration habitat of subyearling fall Chinook salmon Oncorhynchus tshawytscha in John Day Reservoir on the Columbia River. We compared habitats at normal operating pool elevation with habitats at drawdown to spillway crest elevation and drawdown to the historical natural river elevation for two flows (4,417 and 8,495 m3/s). Using two-dimensional hydrodynamic modeling and a predictive habitat model, we determined the quantity and spatial distribution of rearing habitat and predicted water velocities. We predicted that the most habitat area would occur under normal pool elevation, but 93% of habitat was located in the upper third of the reservoir. Although less habitat area was predicted under drawdown to the spillway crest and the natural river, it was distributed more homogeneously throughout the study area. Habitat connectivity, patch size, and percent of suitable shoreline were greatest under drawdown to the natural river elevation. Mean cross-sectional water velocity and the variation in velocity increased with increasing level of reservoir drawdown. Water velocities under drawdown to the natural river were about twice as high as those under drawdown to spillway crest and five times higher than those under normal pool. The variability in water velocity, which may provide cues to fish migration, was highest under drawdown to the natural river and lowest under normal pool elevation. The extent to which different drawdown scenarios would be effective in John Day Reservoir depends in part on restoring normative riverine processes.
Effectiveness of Atimycin-A as a Toxicant for Control of Invasive Asian Swamp Eels
Authors: Reinert Thomas R. , Straight Carrie A. , Freeman Byron J.
Published: November 2006

The Asian swamp eel Monopterus albus is native to southeast Asia but has established populations in several locations within the United States. These eels grow up to 1 m long and may prey on or compete with native fishes and amphibians. Additionally, these eels are obligate air-breathers, can survive long periods out of water, and will travel over land in search of new habitats when necessary. As early as 1990, Asian swamp eels were introduced to several ponds at a local nature center near Atlanta, Georgia, within the Chattahoochee River drainage basin; individuals have since migrated to an adjacent marsh of the Chattahoochee River. Because this population is relatively contained, several methods for control, containment, and possible eradication are being investigated. Juvenile and adult swamp eels primarily obtain oxygen through surface air, although very young eels absorb oxygen directly through their skin. Because they are obligate air-breathers, standard piscicides (e.g., rotenone and antimycin-A) that are transmitted across the gill membrane may not be effective. Nonetheless, we tested the effectiveness of antimycin-A on 2–3-week-old Asian swamp eels in case transmission occurred across the epidermis. We tested antimycin-A concentrations of 2, 5, 10, and 100 nL/L (ppb). No concentration was effective at killing Asian swamp eels, although golden shiners Notemigonus crysoleucas were susceptible at 10 nL/L. Eels that have not undergone metamorphosis (<10 d old) may be susceptible to piscicides such as antimycin-A, but the lack of effectiveness at the early life stage we tested indicates that eradication through such toxicants probably is not a feasible control method.
Diet and Growth of Northern Pike in the Absence of Prey Fishes: Initial Consequences for Persisting in Disturbance‐Prone Lakes
Authors: Venturelli Paul A. , Tonn William M.
Published: November 2006

The northern pike Esox lucius is a renowned piscivore, but will prey opportunistically on invertebrates (e.g., in small lakes of boreal Alberta, where winterkill can unexpectedly reduce or eliminate prey fishes). We emulated such a disturbance by stocking a fishless lake with northern pike and then monitored their diet and growth over two summers. Stomach content analysis revealed that stocked adults responded to the sudden absence of prey fishes by specializing on energy‐rich leeches (families Glossiphoniidae and Erpobdellidae), whereas juvenile offspring consumed a broader mix of invertebrates. Stable isotope analysis supported these results and indicated a relatively rapid drop in the trophic position of stocked adults. Compared with growth of northern pike in regional lakes containing prey fishes, growth of adults in the experimental lake was apparently compromised by a diet of invertebrates but growth of juveniles was high. Although long‐term dynamics of northern pike in these disturbance‐prone lakes are undocumented, our results suggest that northern pike are capable of adapting rapidly to the absence of prey fishes; however, such a diet imposes a trophic bottleneck that can lead to stunting.
Post‐Hydropower System Delayed Mortality of Transported Snake River Stream‐Type Chinook Salmon: Unraveling the Mystery
Authors: Muir William D. , Marsh Douglas M. , Sandford Benjamin P. , Smith Steven G. , Williams John G.
Published: November 2006

Past research indicates that on an annual basis, smolts of stream‐type Chinook salmon Oncorhynchus tshawytscha collected at Snake River dams and transported by barge to below Bonneville Dam have greater post‐hydropower system mortality than smolts that migrate in‐river. To date, this difference has most commonly been attributed to stress from collection and transportation, leading to decreased disease resistance or predator avoidance ability. Using both hatchery and wild passive integrated transponder (PIT) tagged Chinook salmon, we explored two mechanisms that either separately or jointly contributed to an alternative explanation: Altered timing of ocean entry and lost growth opportunity leading to size‐selective predation. Based on weekly estimates of in‐river survival and adult return rates of smolts that were transported or that migrated in‐river between Lower Granite and Bonneville dams, we found greater post‐hydropower system mortality for smolts transported early in the season but greater mortality for in‐river migrating smolts later in the season. Migrants took 2–4 weeks to travel between the two dams, while transported fish took less than 2 d. Thus, fish leaving Lower Granite Dam under the two transit modes encountered different conditions downstream from Bonneville Dam. Further, wild and hatchery migrants grew 6–8 and 5–6 mm, respectively, while transported fish had no apparent growth in the less than 2‐d barge ride. Using length data and regression equations of size selectivity, we found that transported smolts were more vulnerable to predation by northern pikeminnow Ptychocheilus oregonensis (freshwater) and Pacific hake Merluccius productus (marine) than were migrants; this was particularly true for the smaller wild smolts transported early in the season. We concluded that the most parsimonious explanation for differential post‐hydropower system mortality of transported Chinook salmon smolts related not to effects of stress but to differential size and timing of ocean entry.
Strengthening cast iron using FRP composites
Authors: Moy S. , Lillistone D.
Published: November 2006

The current paper deals with the strengthening of large cast iron struts using carbon fibre reinforced polymer composite. It describes the location of the struts in a vent shaft on the London Underground and examines the problems of reinforcing cast iron with conventional materials. A programme of tests on scaled-down struts to demonstrate the benefits of composite strengthening is considered in detail together with a description of the in situ strengthening project.
Improving flexural ductility of high-strength concrete beams
Authors: Kwan A. K. H. , Chau S. L. , Au F. T. K.
Published: November 2006

With the advent of advanced mineral and chemical admixtures, the strength level of concrete has been raised dramatically and high-strength concrete (HSC) is becoming more and more commonly used. However, HSC is generally more brittle than normal strength concrete. In fact, it has been shown that the use of HSC, if not properly controlled, could significantly reduce the flexural ductility of reinforced concrete beams. Herein, it is proposed to compensate for the reduction in flexural ductility owing to the use of HSC by adding compression and confining reinforcements. A parametric study based on complete moment–curvature analysis of beam sections made of different grades of concrete and provided with different amounts of tension, compression and confining reinforcements has been carried out to evaluate the increases in flexural ductility achievable by adding compression and confining reinforcements. From the numerical results, the compression and/or confining reinforcements needed to maintain a consistent level of minimum flexural ductility at all concrete strength levels have been determined and correlated to the concrete strength for direct evaluation in the design of HSC beams.
Multichannel Analysis of Surface Waves Generated During High-resolution Seismic Reflection Profiling of a Fluvial Aquifer
Authors: Harry Dennis L. , Koster John W. , Bowling Jerry C. , Rodriguez Antonio B.
Published: November 2006

Shear wave velocity profiles are estimated from surface wave dispersion analysis of data collected during a high-resolution P-wave reflection survey of a fluvial aquifer located in Columbus, Mississippi. The results demonstrate that useful velocity profiles of the upper [Formula: see text] of a sedimentary sequence can be imaged, even when survey design parameters and noise conditions are not optimal for surface wave surveys. The data were collected with [Formula: see text] geophones, a [Formula: see text] hammer source, and a [Formula: see text] geophone spacing with near and far offsets of 1 and [Formula: see text], respectively. In spite of these less-than-ideal survey parameters for surface wave analysis and the presence of substantial cultural noise arising from nearby quarrying operations and runway activity, the shear velocity profiles accurately locate the boundaries between a shallow soil layer and a meandering fluvial facies in the upper part of the aquifer, and the boundary between the meandering fluvial facies and a braided fluvial facies in the lower part of the aquifer. In general, shear velocities increase with increasing average grain size. Velocities average [Formula: see text] in the soil. In the meandering fluvial facies, velocities increase systematically with depth from [Formula: see text], and correlate with a systematic downward decrease in [Formula: see text] fraction in this upward fining sequence. In the braided fluvial facies, velocities decrease with depth from [Formula: see text], and correlate with a slight downward increase in [Formula: see text] fraction.
Dominant Higher Surface-wave Modes and Possible Inversion Pitfalls
Authors: O’Neill Adam , Matsuoka Toshifumi
Published: November 2006

Dominant higher modes of surface waves are known to be generated at sites with large stiffness contrasts and∕or reversals between layers. At many engineering sites, quite often all modal energy is transferred to successively higher modes with increasing frequency. These ‘jumps’ may occur at low [Formula: see text] to high [Formula: see text] frequencies, and, more than once over the recorded bandwidth, but the common features are that the jumps are in amounts exceeding 50% of the phase velocity, and dispersion does not return to the fundamental mode at high frequency. A nonlinear geophone spacing helps to resolve these modes more uniquely. Full-wavefield synthetic seismogram modelling reinforces the effect to be due to a steep, nonlinear stiffness gradient in the uppermost [Formula: see text] of soil. If a high-velocity substrate at depth is not present, the ‘effective’ phase velocity of the higher modes can exceed that of the maximum shear-wave velocity of the model, where leaky modes persist. When this happens, conventional modal dispersion modelling cannot be applied in the inversion. If an artificial stiff layer is added at depth, jumps across several modal boundaries can occur, which is also generated in a Gibson half-space, both at very low and high frequencies. This is a major pitfall, where mode-misidentification, especially at low frequency, can lead to errors in the estimated shear wave velocity models of over 50%. Guided P-waves also manifest as large dispersion discontinuities, but usually at higher frequency and phase velocities, with buried explosive sources. Although Poisson’s ratio has a strong influence of the generation of—and frequencies of transitions to—dominant higher modes, the higher-mode phase velocities themselves are relatively independent of shallow P-wave velocity.
Evaluation of MASW Data Acquired with a Hydrophone Streamer in a Shallow Marine Environment
Authors: Kaufmann Ronald D. , Xia Jianghai , Benson Richard C. , Yuhr Lynn B. , Casto Daniel W. , Park Choon B.
Published: November 2006

Seismic shear wave velocity is an important characteristic of sub-bottom materials for geotechnical and environmental characterizations in marine environments. Traditional marine shear wave velocity measurements utilize measurements within borings or data from geophones planted on the bottom. Multichannel Analysis of Surface Waves (MASW) provides a more efficient means to estimate shear wave velocity values of sub-bottom materials using a hydrophone streamer and an airgun seismic source. MASW data were acquired in a shallow marine environment and on adjacent land. Land data were acquired with a traditional spread of geophones, while the marine data were acquired with a 24-channel hydrophone streamer laid on the bottom. Phase velocity frequency spectra calculated from the data indicate that the measurements on land are repeatable with measurements underwater. Shear-wave velocity models estimated from the dispersion curves are consistent with each other and with expected geologic conditions. However, the shear-wave velocity models are strongly dependent on the model parameterization and the accuracy of the dispersion curves. Limitations include an observed narrower bandwidth of marine surface wave energy and noise resulting from towing the streamer with a boat.
Genetic Algorithm Inversion of Rayleigh Wave Dispersion from CMPCC Gathers Over a Shallow Fault Model
Authors: Nagai Keiji , O’Neill Adam , Sanada Yoshinori , Ashida Yuzuru
Published: November 2006

Lateral shear-wave velocity imaging, based on 1D surface wave inversion, is becoming routine in commercial site characterisation. A Genetic Algorithm (GA) is applied to the inversion of fundamental mode Rayleigh wave dispersion over a 3-layered, shallow, vertical-fault model. The data are calculated using a 2D finite difference method, then sorted into CMP cross-correlated (CMPCC) gathers, from which the dispersion is measured. Dispersion is relatively smooth over flat portions of the model, as well as when the spread is equally centered over the sharp lateral discontinuity. When between one and two-fifths of the spread is “overhanging” the fault, low-frequency dispersion is corrupted by wavefield scattering. Each dispersion curve is inverted using a 1D forward model, constrained to four layers, with parameters allowed to vary within liberal limits except the layer 1 shear-wave velocity. A novel variation is that the optimisation is partially directed, by including the most successful shear-wave velocity model in the initial GA population at successive midpoints, essentially laterally constraining the inversion. When the rollalong dispersion curves are inverted, both in “continuous” and “segmented” progressions, the 2D pseudo-section clearly shows the smoothing effect encountered across a sharp lateral geological discontinuity, causing a “palaeochannel” appearance, rather than a vertical fault. However, the estimated locations of shallow and deep layer truncations can better map the position of the abrupt lateral discontinuity, rather than simply basement topography. The RMS misfit between measured and theoretical dispersion curves gives no indication of where the 1D assumption breaks down and the exact discontinuity lies.
Land Streamer Aided Geophysical Studies at Saqqara, Egypt
Authors: Miller Carlyle R. , Allen Amy L. , Speece Marvin A. , El-Werr Abdel-Khalek , Link Curtis A.
Published: November 2006

During December 2002 and January 2003, Montana Tech in collaboration with Ain Shams University, Cairo, collected Ground Penetrating Radar (GPR) and seismic data at Saqqara, Egypt. The purpose of this study was to see if GPR and seismic methods could detect manmade structures in the subsurface at Saqqara. In particular, land streamer aided, seismic diving-wave tomography was tested as a method to detect archaeological features. Saqqara was one of the principal necropolises of Memphis, an ancient capital of Egypt. The research site was near the 3rd Dynasty pharaoh Djoser’s Step Pyramid—the first monumental structure built entirely of stone. A preliminary GPR study of our site yielded numerous, possibly manmade features in the subsurface with a [Formula: see text] depth of penetration using [Formula: see text] antennas. A follow-up three-dimensional (3-D) GPR survey over one of the more interesting features showed a broad trench underneath the flat-lying sand that is seen at the surface. This feature is most likely manmade because the horizontally layered limestone rocks of Saqqara are inconsistent with the shape of this feature. Seismic diving-wave tomograms show that this probable manmade feature extends to a depth of [Formula: see text] into the subsurface. Moreover, we were able to complete the seismic survey faster using a land streamer consisting of gimbaled geophones than could be done using conventional planted geophones. This site has potential for further investigation and possible excavation.
A Study of H1 NMR Signal from Hydrated Synthetic Sands
Authors: Bray C. L. , Schaller N. C. , Iannopollo S. L. , Bostick M. D. , Ferrante G. , Fleming A. , Hornak J. P.
Published: November 2006

Magnetic resonance imaging (MRI) has recently been proposed as an in situ subsurface imaging technique for locating buried objects in fully hydrated soils. This paper explores the available hydrogen [Formula: see text] nuclear magnetic resonance (NMR) signal from water in fully hydrated monodispersed synthetic sands (glass beads) as a predictor of the utility of subsurface MRI. The MRI signal from hydrated soils is a function of three main properties of water in the voids between the soil particles: the spin-lattice relaxation rate [Formula: see text], the spin-spin relaxation rate [Formula: see text], and the spin density [Formula: see text]. The [Formula: see text] values were measured for random close packed synthetic sands as a function of particle diameter. The [Formula: see text] and [Formula: see text], values were measured at a magnetic field strength of [Formula: see text] as a function of particle diameter. [Formula: see text] was also measured as a function of magnetic field strength at 0.235, 2.35, 23.5, and [Formula: see text]. The synthetic sands studied have a predictable [Formula: see text] and [Formula: see text], and a constant [Formula: see text]. The water in these sands also has a predictable [Formula: see text] as a function of applied magnetic field. Therefore, fully hydrated monodispersed real sands are expected to have a predictable NMR signal.
The Magnetic Detection of Sunken Ships in the Madang Section of the Yangtze River
Authors: Wang Chuanlei , Qu Zan , Qi Mingsong , Shen Bo
Published: November 2006

The Yangtze River is not only the largest river in China, but also the most important water transportation artery. Some parts of the river, however, still have barricades formed from sunken ships emplaced during the Anti-Japanese War on the Chinese mainland (World War II) to interfere with shipping. The Madang section, with its shallow water depth and the blockage in the channel, has raised safety concerns for transportation on the Yangtze River. This paper discusses the detection of sunken ships on the Madang section using a geophysical technique and describes general procedures for conducting high precision magnetic surveys on water. It also introduces an approach for recognizing the interference caused by nearby moving boats. Finally, it discusses the techniques used to accurately determine the position and quantity of ships buried at the bottom of the river from the magnetic data. The seven sunken ships that were identified from the magnetic data in this survey area were raised in a subsequent salvage operation. The positions and dimensions of the sunken ships deduced from magnetic data coincide with the locations and sizes reported by divers. For example, the estimated length of the ship associated with anomaly M4 is [Formula: see text] in length, and the actual length measured by divers in water is [Formula: see text]. No other sunken ships have been found by the transportation company in charge of the salvage operation subsequent to the removal of the seven sunken ships mentioned above. This indicates that a magnetic survey is the most effective technique to detect submerged ships.
An Integrated Geophysical and Archaeological Investigation of the Emperor Qin Shi Huang Mausoleum
Authors: Yuan Bingqiang , Liu Shiyi , Lu Guoyin
Published: November 2006

Integrated geophysical methods that included high-precision gravity, magnetic, electrical resistivity tomography, radioactive radon, and ground-penetrating radar surveys were used to investigate the underground palace of China’s first Emperor, Qin Shi Huang, his Mausoleum, and its appurtenant structures (i.e., pits and tombs). Successful identification of the underground palace’s distribution, as well as a thin-compacted wall and coffin chambers in the burial mound, as interpreted from analysis of the geophysical data, was corroborated by subsequent excavation. The effectiveness of the integrated procedures was also demonstrated on the known auxiliary pits and tombs adjacent to the main buried palace structure. These results are the most significant recent discoveries at the Emperor Qin Shi Huang Mausoleum, as well as the general mausoleum architecture in the Qin dynasty.
Integrated Geophysical Techniques in Detecting Hidden Dangers in River Embankments
Authors: Chen Chao , Liu Jiangping , Xia Jianghai , Li Zhenyu
Published: November 2006

Noninvasive geophysical technologies are often used for detecting hidden defects and monitoring seepage in dams. In 2003 a series of experiments were conducted to detect and discover hidden defects in the embankment of the Yangtze River, Songzi County, Hubei Province, China. High-resolution reflection and surface-wave seismic methods with non-explosive sources were used to investigate the structure of the embankment and to obtain the shear (S)-wave velocity profile of different materials. As an effective approach for investigating groundwater, a DC multi-channel resistivity survey was also used to evaluate the moisture content of material inside and under the embankment. This paper discusses the exploration strategy and preliminary results for several sections of the embankment. Based on the experimental data, seismic reflection images and S-wave velocity contours are used to describe embankments geometrically and qualitatively. Known anomalies are identified on seismic profiles. A practical approach, which combines seismic and electric resistivity data, is proposed to locate potential seepage sites in the embankment. The new method is used to evaluate seepage potential and the presence of anomalies using the S-wave velocity and the resistivity of the medium. An anomaly detected in a section of the embankment was verified where piping occurred during 1998 flooding.
The Impact of Multifactorial Genetic Disorders on Critical Illness Insurance: A Simulation Study Based on UK Biobank
Authors: Macdonald Angus , Pritchard Delme , Tapadar Pradip
Published: November 2006

The UK Biobank project is a proposed large-scale investigation of the combined effects of genotype and environmental exposures on the risk of common diseases. It is intended to recruit 500,000 subjects aged 40-69, to obtain medical histories and blood samples at outset, and to follow them up for at least 10 years. This will have a major impact on our knowledge of multifactorial genetic disorders, rather than the rare but severe single-gene disorders that have been studied to date. What use may insurance companies make of this knowledge, particularly if genetic tests can identify persons at different risk? We describe here a simulation study of the UK Biobank project. We specify a simple hypothetical model of genetic and environmental influences on the risk of heart attack. A single simulation of UK Biobank consists of 500,000 life histories over 10 years; we suppose that case-control studies are carried out to estimate age-specific odds ratios, and that an actuary uses these odds ratios to parameterise a model of critical illness insurance. From a large number of such simulations we obtain sampling distributions of premium rates in different strata defined by genotype and environmental exposure. We conclude that the ability of such a study reliably to discriminate between different underwriting classes is limited, and depends on large numbers of cases being analysed.
Optimal Dynamic Reinsurance
Authors: Dickson David C.M. , Waters Howard R.
Published: November 2006

We consider a classical surplus process where the insurer can choose a different level of reinsurance at the start of each year. We assume the insurer’s objective is to minimise the probability of ruin up to some given time horizon, either in discrete or continuous time. We develop formulae for ruin probabilities under the optimal reinsurance strategy, i.e. the optimal retention each year as the surplus changes and the period until the time horizon shortens. For our compound Poisson process, it is not feasible to evaluate these formulae, and hence determine the optimal strategies, in any but the simplest cases. We show how we can determine the optimal strategies by approximating the (compound Poisson) aggregate claims distributions by translated gamma distributions, and, alternatively, by approximating the compound Poisson process by a translated gamma process.
Tail Variance Premium with Applications for Elliptical Portfolio of Risks
Authors: Furman Edward , Landsman Zinoviy
Published: November 2006

In this paper we consider the important circumstances involved when risk managers are concerned with risks that exceed a certain threshold. Such conditions are well-known to insurance professionals, for instance in the context of policies involving deductibles and reinsurance contracts. We propose a new premium called tail variance premium (TVP) which answers the demands of these circumstances. In addition, we suggest a number of risk measures associated with TVP. While the well-known tail conditional expectation risk measure provides a risk manager with information about the average of the tail of the loss distribution, tail variance risk measure (TV) estimates the variability along such a tail. Furthermore, given a multivariate setup, we offer a number of allocation techniques which preserve different desirable properties (sub-additivity and fulladditivity, for instance). We are able to derive explicit expressions for TV and TVP, and risk capital decomposition rules based on them, in the general framework of multivariate elliptical distributions. This class is very popular among actuaries and risk managers because it contains distributions with marginals whose tails are heavier than those of normal distributions. This distinctive feature is desirable when modeling financial datasets. Moreover, according to our results, in some cases there exists an optimal threshold, such that by choosing it, an insurance company minimizes its risk.
Dynamic Portfolio Selection in a Dual Expected Utility Theory Framework
Authors: Cenci Marisa , Corradini Massimiliano , Gheno Andrea
Published: November 2006

In this paper the dynamic portfolio selection problem is studied for the first time in a dual utility theory framework. The Wang transform is used as distortion function and well diversified optimal portfolios result both with and without short sales allowed.
On Bayesian Mixture Credibility
Authors: Lau John W. , Siu Tak Kuen , Yang Hailiang
Published: November 2006

We introduce a class of Bayesian infinite mixture models first introduced by Lo (1984) to determine the credibility premium for a non-homogeneous insurance portfolio. The Bayesian infinite mixture models provide us with much flexibility in the specification of the claim distribution. We employ the sampling scheme based on a weighted Chinese restaurant process introduced in Lo et al. (1996) to estimate a Bayesian infinite mixture model from the claim data. The Bayesian sampling scheme also provides a systematic way to cluster the claim data. This can provide some insights into the risk characteristics of the policyholders. The estimated credibility premium from the Bayesian infinite mixture model can be written as a linear combination of the prior estimate and the sample mean of the claim data. Estimation results for the Bayesian mixture credibility premiums will be presented.
Adverse Selection Spirals
Authors: Jong Piet De , Ferris Shauna
Published: November 2006

This article discusses risk classification and develops and discusses a framework for estimating the effects of restrictions on risk classification. It is shown that expected losses due to adverse selection depend only on means, variances and covariances of insurance factors and rates of uptake of insurance. Percentage loadings required to avoid losses are displayed. Correlated information, such as family history, is also incorporated and it is seen how such information limits losses and decreases required loadings. Although the evidence suggests that adverse selection is not, at present, a severe problem for insurers, this might change if the authorities impose restrictions on risk classification and/or customers gain an informational advantage (such as better knowledge of their own risk levels). Application is made to unisex annuity pricing in the UK insurance market.
The Mean Square Error of Prediction in the Chain Ladder Reserving Method – A Comment
Authors: Mack Thomas , Quarg Gerhard , Braun Christian
Published: November 2006

We discuss some questionable points of the approach taken in the paper by Buchwalder, Bühlmann, Merz and Wüthrich and come to the conclusion that this approach does not yield an improvement of Mack’s original formula. The main reason is that the new approach disregards the negative correlation of the squares of the development factors. The same applies to the formula by Murphy (PCAS 1994).
Use of cisplatin-containing biodegradable beads for treatment of cutaneous neoplasia in equidae: 59 cases (2000–2004)
Authors: Hewes Christina A. , Sullins Kenneth E.
Published: November 2006

Objective—To determine outcome for equids with cutaneous neoplasms treated with cisplatin-containing biodegradable beads, alone or in conjunction with debulking.

Design—Retrospective case series.

Animals—56 horses, 1 zebra, 1 donkey, and 1 mule.

Procedures—Medical records were reviewed. Follow-up information was obtained through telephone conversations with owners and trainers of the animals.

Results—22 tumors were sarcoids, 6 were fibrosarcomas, 1 was a fibroma, 2 were peripheral nerve sheath tumors, 11 were squamous cell carcinomas, 14 were melanomas (13 gray horses and 1 bay horse), 1 was a lymphosarcoma, 1 was an adenocarcinoma, and 1 was a basal cell tumor. Forty-five (76%) animals underwent conventional or laser debulking of the tumor prior to bead implantation. Forty of 48 (83%) animals for which long-term follow-up information was available were relapse free 2 years after treatment. This included 20 of 22 animals with spindle cell tumors (including 11/13 horses with sarcoids), 6 of 10 animals with squamous cell carcinomas, 13 of 14 animals with melanomas, and 2 of 3 animals with other tumor types. Adverse effects were minimal.

Conclusions and Clinical Relevance—Results suggest that implantation of cisplatin-containing biodegradable beads, with or without tumor debulking, may be an effective treatment for equidae with various cutaneous neoplasms.
Cationic surfactant‐selective potentiometric sensors based on neutral ion‐pair carrier complexes
Authors: Mahajan Rakesh Kumar , Kaur Inderpreet , Bakshi Mandeep Singh
Published: November 2006

Poly(vinyl chloride) (PVC) membrane electrodes to determine monomer concentrations of tetradecyltrimethylammonium ion (TTA+) and hexadecylpyridinium ion (HPy+) based on neutral ion‐pair carrier complexes of tetradecyltrimethylammonium dodecyl sulfate (TTA+‐DS−) and hexadecylpyridinium dodecyl sulfate (HPy+‐DS−), respectively, are reported here. The electrodes exhibit a Nernstian slope of 59 mV per decade for TTA+ and a sub‐Nernstian slope of 34.5 mV per decade for HPy+ ions. The TTA+ ion‐selective electrode (ISE) and the HPy+‐ISE can determine the monomer units down to concentrations as low as 4.0×10−4M and 1.66×10−5 M, respectively. The effect of various additives, such as the anionic polyelectrolyte sodium dextran sulfate and macrocyclic β‐cyclodextrin, on the surface activity exhibited by the cationic surfactants TTA+‐DS− and HPy+‐DS−, in the presence of background concentrations of NaCl was also examined with surfactant‐selective sensors. The Gibbs free energy of micelle formation (ΔGm) of both surfactants in the presence of various additives was calculated and found to be less favorable with respect to an increase in the amount of additives due to less availability of cationic surfactant monomer units. The ion‐pair complexes TTA+‐DS− and HPy+‐DS− were found to behave as selective carrier compounds in PVC membranes in determining the concentration of monomer units of both TTA+ and HPy+, respectively. The proposed sensors worked well at a fairly acidic pH of 1–6.5 with response time of 60 s. The sensors responded well to the surfactant ions even in the presence of additives at lower concentration. The lifetime of the sensors is 3 mon.
Primary aerobic biodegradation of cationic and amphoteric surfactants
Authors: Qin Yong , Zhang Gaoyong , Kang Baoan , Zhao Yumei
Published: November 2006

The primary aerobic biodegradation of several cationic and amphoteric surfactants has been studied by using the shaking‐flask degradation test and orange II spectrophotometric analysis. The results show that cationic and amphoteric surfactants can be readily biodegraded, with their degradation exceeding 94%. The degradation kinetics can be accurately described by the Boltzmann model. The relationship between structure and biodegradability is discussed. The presence of hydrophobic groups has a strong effect on the biodegradability of these surfactants. Biodegradability decreases with increasing chain length. The presence of hydrophilic groups mainly affects the degradation rate of these surfactants, but not their ultimate biodegradeability. Bio‐degradability is deterred and degradation is slowed as steric hindrance increases. Degradation rates increase markedly when hydrophilic groups containing an amide bond are pres‐ent.
Synthesis of new extended surfactants containing a xylitol polar group
Authors: Fernández Alvaro , Scorzza Cesar , Usubillaga Alfredo , Salager Jean‐Louis
Published: November 2006

A new class of extended surfactants was prepared in which the spacer arm between the polar portion and the hydrophobic alkyl chain was a polymer of propylene glycol with an average length of six propylene oxide units. The polar head was a single or double xylitol moiety or a xylitol molecule with carboxylic acid functionality. Surfactants containing double xylitol polar head groups showed a much higher critical micelle concentration value than surfactants with a single polar head.
Glycerol esters from the reaction of glycerol with dicarboxylic acid esters
Authors: Cho Gladys H. P. , Yeong S. K. , Ooi T. L. , Chuah C. H.
Published: November 2006

Mono‐ and di‐esterified glycerols were synthesized by the base catalyzed reaction of glycerol with aliphatic dicarboxylic acid esters (C2−C9): 2,3‐dihydroxy‐propyl oxalate (2), 1,3 dioxalyloxy propan‐2‐ol (3), 1,3‐dimethoxyoxalyloxy propan‐2‐ol (5), 2,3‐dihydroxy‐propyl malonate (6), 2,3‐dihydroxy‐propyl methyl malonate (7), 2,3‐dihydroxy‐propyl methyl succinate (8), 1,3‐dimethoxysuccinyloxy propan‐2‐ol (9), 2,3‐dihydroxy‐propyl methyl glutarate (10), 1,3‐dimethoxyglutaryloxy propan‐2‐ol (11), 2,3‐dihydroxy‐propyl methyl azelate (14), and 1,3‐dimethoxyazelyloxy propan‐2‐ol (15). Their structures were elucidated by spectrometric methods. Compounds 8, 10, 2,3‐dihydroxy‐propl methyl adipate (12) and 14 were found to possess surface active properties and the ability to reduce the interfacial tension between paraffin and water.
Mixed micelles of some anionic‐anionic, cationic‐cationic, and ionic‐nonionic surfactants in aqueous media
Authors: Vora Sambhav , George Alex , Desai Hemangi , Bahadur Pratap
Published: November 2006

Critical micelle concentrations (CMC) were obtained from tensiometric studies on several binary surfactant mixtures (anionic‐anionic, cationic‐cationic, anionic‐nonionic, and cationic‐nonionic) in water at different mole fractions (0–1). The composition of mixed micelles and the interaction parameter β, evaluated from the CMC data for different systems using Rubingh's theory, are discussed. Marked interaction is observed for ionic‐nonionic systems, whereas it is weak in the case of similarly charged surfactants. The influence of counterion valence in the formation of mixed micelles was investigated, and results suggest that in similarly charged surfactant mixtures, the degree of counterion binding does have a major role in deciding the extent of interactions. Salt addition reveals a weakening of interactions in ionic‐nonionic systems, and this is attributed to head group charge neutralization and dehydration of the ethylene oxide units of the nonionic surfactants. Cloud point and viscosity data on these systems support the observation.