bluuebunny/crossref_metadata_2025 huggingface dataset:
Avoidance of Pentachlorophenol by Postlarval Brown Shrimp (Penaeus aztecus) (Decapoda, Penaeidae) in a Laminar-Flow Choice Chamber
Authors: Benfieid Mark C. , Aldrich David V.
Published: October 2008

Responses of postlarval brown shrimp (Penaeus aztecus) to pentachlorophenol (0–450 μg∙L−1) were measured in synthetic seawater and estuarine water using a laminar-flow choice chamber. This chamber provides individual postlarvae with equal exposure to two parallel olfactant streams separated by a steep concentration gradient. Shrimp detected and avoided pentachlorophenol concentrations above 91 μg∙L−1 in synthetic seawater. This detection threshold reflects limitations in statistical power, and with increased replication the physiological threshold could probably be resolved at a much lower concentration. Pentachlorophenol appeared to be more repellent when dissolved in estuarine water from Galveston Bay, Texas. The 96-h LC50 for pentachlorophenol was 317 μg∙L−1 which suggests that postlarvae are capable of avoiding acutely toxic concentrations of this pollutant. For postlarvae of this species, behavioral avoidance appears to provide a more sensitive indicator of pollutant responses than the conventional toxicity bioassay.
Why Are the PCB Concentrations of Salmonine Individuals from the Same Lake So Highly Variable?
Authors: Madenjian Charles P. , Carpenter Stephen R. , Rand Peter S.
Published: October 2008

An individual-based model (IBM) was applied to the Lake Michigan rainbow trout (Oncorhynchus mykiss) population, with the objectives of explaining the observed variation in growth and in polychlorinated biphenyl (PCB) concentration within the population. When variation in prey PCB concentration was incorporated into the model, variability in PCB concentration among individual rainbow trout was fully explained by the IBM. Although number of spawnings and number of years spent in a stream prior to first entering the lake were factors in determining growth, these life history characteristics appeared to have only a minor impact on PCB accumulation rate in rainbow trout. The IBM application to the rainbow trout population was compared with an application to the Lake Michigan lake trout (Salvelinus namaycush) population. Modeling results indicated that the lower observed PCB concentrations in rainbow trout compared with lake trout were chiefly due to greater longevity in lake trout. The IBM simulations identified gross growth efficiency, assimilation efficiency of PCBs from food, and diet as other important sources of variability in salmonine PCB concentrations.
Geographic Responses of Groundfish to Variation in Abundance: Methods of Detection and Their Interpretation
Authors: Marshall C. Tara , Frank Kenneth T.
Published: October 2008

Recent published studies have used data from bottom trawl surveys of groundfish populations to test whether distributional area and abundance are correlated. Two studies that used different indices to represent the distributional area of Georges Bank haddock (Melanogrammus aeglefinus) yielded conflicting results. To determine whether this is an example of different distributional indices measuring different things, both indices were regressed against estimates of abundance of haddock from a different but neighbouring location on the southwestern Scotian Shelf. Positive correlations were observed for immature age-classes using both indices whereas only one of the two indices resulted in positive correlations for mature age-classes. The following factors contributed to the lack of agreement among distributional indices: (1) age-aggregated indices potentially obscure correlations between distributional area and abundance for individual age-classes; (2) distributional indices that depend on the magnitude of catch rates confound variation in the large-scale horizontal distribution of stocks with diurnal variation in the three-dimensional distribution of schools; (3) distributional indices that scale positively with abundance generate spurious correlations. The results suggest that the outcome of any test of whether distributional area and abundance are correlated depends on the index chosen to represent distributional area.
Accuracy and Choice in Risk Estimation for Fisheries Assessment
Authors: Cordue P. L. , Francis R. I. C. C.
Published: October 2008

Risk analysis has been used recently to enhance scientific advice to managers by providing estimates of risk to the fishery of different management strategies. However, little consideration has been given to the accuracy of these estimates. We present a reformulation and generalization of the risk analysis procedure of Francis (1992. Can. J. Fish. Aquat. Sci. 49: 922–930) and use simulation methods to examine the properties of a number of alternative risk estimators for two of New Zealand's main fisheries. It is shown that the choice of estimator can strongly affect the final estimates of risk and that the risk estimators can be alarmingly inaccurate. The accuracy of estimates is also shown to vary according to the type of risk being estimated, so analysts may improve the accuracy of their estimates by choosing the type of risk they estimate.
Assessing Smoltification of Juvenile Spring Chinook Salmon (Oncorhynchus tshawytscha) Using Changes in Body Morphology
Authors: Beeman J. W. , Rondorf D. W. , Tilson M. E.
Published: October 2008

A morphometric measure of smoltification of juvenile spring chinook salmon (Oncorhynchus tshawytscha) was developed and evaluated. Fish were collected from hatcheries in Washington and Idaho prior to release and at McNary Dam on the Columbia River during their downstream migration. Distances between 15 anatomical landmarks were digitized from photographs of each fish resulting in 34 morphometric characters for analysis. The canonical variate calculated from a discriminant function based on several principal components was evaluated as a measure of smoltification. The canonical variate was significantly correlated with gill Na+–K+ ATPase activity, a commonly used measure of smoltification. Measuring the morphometric characters and calculating the canonical variate is a relatively simple procedure and can be performed with little harm to the fish. This method of smoltification assessment may be ideally suited to studies in which sacrificing fish is not possible, such as those involving threatened or endangered species, or when access to a laboratory for sample analysis is not available.
ARROW Oil Spill, 1970–90: Persistence of 20-yr Weathered Bunker C Fuel Oil
Authors: Vandermeulen J. H. , Singh J. G.
Published: October 2008

A full range of weathered petroleum residues persist in two beach sites in Chedabucto Bay, Nova Scotia, 20 yr after the ARROW Bunker C spill. Both sites contained ARROW bunker fuel residues (pentacyclic triterpane characterization). Residues from "tar pavement" and a tar deposit within a cobble spit retained many components of original ARROW Bunker C fuel. Results indicate that long-term persistence is a direct function of beach sediment permeability, and of the depth to which entrapped tar residues penetrate; persistence is an inverse function of the frequency and depth of sediment reworking during tidal incursions. Cobble beaches represent an extreme example, with the interstices acting as low-energy sinks for spilled oil. A revised model for oil stranding and fate proposes two distinct environmental reservoirs of stranded oil residue in these medium-grained beaches: the interstitual residue as the major long-term source and surface-stranded residue as the minor source, each with its own weathering rate, history, and persistence. Such in-beach sequestered oils undergo much slower weathering than surface-stranded residues, persist longer, and continue to be remobilized. However, actual transfer of hydrocarbons from such deposits to tidal waters is very low (ppb).
Daily Settlement Rates of the Zebra Mussel, Dreissena polymorpha, on an Artificial Substrate Correlate with Veliger Abundance
Authors: Martel André , Mathieu Andrea F. , Findlay C. Scott , Nepszy Stephen J. , Leach Joseph H.
Published: October 2008

The relationship between daily settlement rates and local concentrations of veligers of the zebra mussel, Dreissena polymorpha, was investigated using plankton sampling and scouring pad collectors. A total of 102 plankton and 136 collector samples were taken from a nearshore site near Wheatley, Ontario, in west-central Lake Erie, over 17 consecutive d in August 1992. Results demonstrate a strong correlation between daily settlement rates and daily concentrations of late-stage (competent) veligers in the water column (determined at shell lengths ≥ 170 μm; r = 0.93–0.98; p < 0.001; log10-transformed data). Variations in settlement rates of 1–3 orders of magnitude occurred within 24–96 h. Results also suggest that wind-induced hydrodynamics can affect settlement rates of zebra mussel larvae; the period used to monitor settlement (24 h) was much shorter than that employed (~1–2+ wk) in previous studies. Daily monitoring of concentrations of late-stage veligers in the water column as well as settlers (fibrous collectors) may help to identify biological and physical factors affecting short-term variability in settlement; it may also prove advantageous for industries where early detection of colonization by the zebra mussel is critical for cost-effective control of this invasive mollusc.
Interannual Variability of Nitrogen Limitation in a Desert Lake: Influence of Regional Climate
Authors: Lebo Martin E. , Reuter John E. , Goldman Charles R. , Rhodes Cathryn L.
Published: October 2008

A systematic evaluation of limnological and experimental indicators of nutrient limitation in Pyramid Lake during 1989–92 clearly show that N is the nutrient most limiting to phytoplankton. This conclusion is supported by dissolved inorganic nutrient ratios, seston elemental composition, nutrient enrichment bioassay experiments, and blooms of N2-fixing algae. However, the degree of N limitation expressed during the three years varied considerably. A comparison of interannual patterns of N limitation with weather data collected at the lake suggests that differences among years can be attributed to climatic variations. Our study indicates that climatic variations affect N availability by altering the timing of winter deep mixing, varying the potential for upwelling during spring, and varying the rate of spring warming of surface waters. Summer wind patterns also appear to be an integral factor controlling initiation, development, and collapse of the annual bloom of Nodularia spumigena, a N2-fixing blue-green alga. The results of this study emphasize the need to consider climatic variations in assessing the general nutrient status of lakes.
Oceanographic Basis of a DMS-Related Atlantic Cod (Gadus morhua) Fishery Problem: Blackberry Feed
Authors: Levasseur M. , Keller M. D. , Bonneau E. , D'Amours D. , Bellows W. K.
Published: October 2008

Atlantic cod (Gadus morhua) caught along the Labrador and Newfoundland coasts and in the Strait of Belle Isle often smell strongly of sulfur, a problem locally called "blackberry feed". Early studies have shown that the sulfurous-smelling cod had fed almost exclusively on the pteropod Limacina helicina and that dimethylsufide (DMS) was responsible for the odor. In August 1991, we conducted a cruise in the northeastern Gulf of St. Lawrence and in the Strait of Belle Isle in order to confirm the algal origin of dimethylsulfoniopropionate (DMSP, the precursor of DMS) and to determine the factors responsible for its transfer in the food web. A significant correlation was found between the distribution of DMSP and the abundance of microflagellates, dinoflagellates, cryptomonads, and prymnesiophytes (mostly Chrysochromulina spp.). The concentration of DMSP in L. helicina and in particles were also linearly related, suggesting rapid accumulation of DMSP in pteropod. The weight-specific DMSP content of L. helicina was always high (1–21 mg DMSP/g) and apparently sufficient to create blackberry feed symptoms in cod. Results from bioassay experiments demontrated that L. helicina may significantly influence the DMSP–DMS dynamics in subarctic waters.
Effect of Coastal Winds on the Summer Dispersal of Young Least Cisco (Coregonus sardinella) from the Colville River to Prudhoe Bay, Alaska: A Simulation Model
Authors: Fechhelm Robert G. , Bryan James D. , Griffiths William B. , Wilson William J. , Gallaway Benny J.
Published: October 2008

A one-dimensional advection model was used to simulate the movement of young (< 180 mm) anadromous least cisco (Coregonus sardinella) along the Beaufort Sea coast between the Colville River and Prudhoe Bay, Alaska. Two versions of the model simulated eastward movement during the month of July as the sum of wind-induced transport and constant dispersion. Model results were compared with fyke-net catch data collected from 1981 to 1992. Of the 12 years examined, the models correctly simulated no major arrival of fish in 1983, 1985, 1986, 1987, and 1992, simulated the exact day of arrival in 1981, 1989, and 1991, and were in error by 1 d in 1988. Approximately 71% of the error between simulated and observed arrival dates was associated with three specific years: 1982, 1984, and 1990. The model suggests that wind-governed circulation may reasonably account for the presence of young Colville River least cisco in the Prudhoe Bay area. Results are discussed in terms of their relevance for assessing the effects of Arctic oil development on regional fishery resources.
An Age-Structured Open-Access Fishery Model
Authors: McGarvey Richard
Published: October 2008

A dynamic model for open-access fisheries is presented. In addition to density dependence in recruitment and fishing effort changing in proportion to the level of profit fishermen earn which characterizes previous open-access models, it incorporates full age structure for the fish stock, lognormal environmental recruitment variability, and gear selectivity. The predator–prey cycling solution of the original Schaefer dynamic model, and subsequent open-access models, persists for these model extensions. Density dependence in recruitment induces greater global stability. Environmental recruitment variability, common in marine populations, is destabilizing in the neighborhood of the open-access equilibrium. These two influences, combined in the open-access fishery model, generate robust long-lasting irregular cycles of stock and effort. Volterra proved for the original Lotka–Volterra model that the time averages of the variables over one cycle were exactly equal to their equilibrium steady states. This is shown to extend as a good approximation for the model presented here. Approximating model steady states of effort and catch by the corresponding averages from data time series underlies a new algorithm of parameter evaluation, applied here to an open-access model of the Georges Bank sea scallop (Placopecten magellanicus) fishery.
Gape-dependent Larval Foraging and Zooplankton Size: Implications for Fish Recruitment across Systems
Authors: Bremigan Mary T. , Stein Roy A.
Published: October 2008

Small gape of zooplanktivorous larval fish limits their prey size; yet, within constraints set by gape, zooplankton size eaten influences larval growth and ultimately survival. To determine if optimal zooplankton size varied among fish species with different gapes, we conducted foraging trials with larval bluegill (Lepomis macrochirus, 10–26 mm TL) and gizzard shad (Dorosoma cepedianum, 18–31 mm TL). Larvae (n = 10) fed for 1 h on zooplankton assemblages that varied in size, after which all larvae and remaining zooplankton were preserved. Larval gape was measured; both larval gut contents and available zooplankton were quantified. Bluegill, the large-gaped species, fed on larger zooplankton than did gizzard shad with similar gapes. Further, larger bluegill fed on progressively larger zooplankton whereas all gizzard shad ate small prey (< 0.60 mm). As available zooplankton size increased, bluegill prey size increased whereas gizzard shad consistently selected small prey. Therefore, differences in zooplankton size among lakes could differentially affect foraging success of larval fishes. In particular, systems with small zooplankton may represent ideal foraging environments for gizzard shad whereas lakes with large zooplankton may favor larval bluegill. If differential larval foraging translates to differential growth and survival, zooplankton size could influence recruitment success and ultimately fish community composition.
Larkin's Predation Model of Lake Trout (Salvelinus namaycush) Extinction with Harvesting and Sea Lamprey (Petromyzon marinus) Predation: A Qualitative Analysis
Authors: Jensen A. L.
Published: October 2008

After invasion of the Great Lakes by the parasitic marine sea lamprey (Petromyzon marinus), lake trout (Salvelinus namaycush) populations crashed, but there remains some uncertainty concerning the relative importance of sea lamprey predation and harvesting in destruction of the fisheries. Some investigators believe overharvest was important; others think that the sea lamprey alone was enough. Simple models of predation assume monophagous predators and do not predict extinction of prey, but Larkin's modification of the Lotka–Volterra model results in extinction under some circumstances. The dynamics of sea lamprey predation on lake trout were investigated using Larkin's model, and crude estimates of the model parameters indicate that extinction is a likely outcome with or without a fishery.
Trends in the Abundance of Chinook Salmon (Oncorhynchus tshawytscha) of the Nechako River, British Columbia
Authors: Bradford Michael J.
Published: October 2008

Trends in abundance of chinook salmon (Oncorhynchus tshawytscha) of the Nechako River, a tributary of the Fraser River, were analyzed to quantify the ecological effects of water abstraction for electricity generation. In years when the majority of returning chinook adults used the upper Nechako River for spawning, the survival of offspring for the entire river was poorer than in years when spawning was concentrated in the lower reaches. Relative to the historical discharge, the upper Nechako River has experienced the greatest degree of water abstraction, and the lower survival of chinook broods originating from the upper river may be due to early emergence of fry caused by elevated fall and winter water temperatures or to higher rates of predation on juveniles and loss of rearing habitat caused by the elimination of the spring freshet. Poor recruitment resulting from broods spawning predominately in the upper river has caused the trend in the abundance of Nechako River chinook to diverge from the trend of chinook populations of similar life history from unregulated tributaries of the Fraser River. Additional reductions in flow may further affect the capacity of the upper Nechako River to produce chinook salmon.
Teleparallel version of the Levi–Civita vacuum solutions and their energy contents
Authors: Sharif M , Amir M Jamil
Published: October 2008

In this paper, we find the teleparallel version of the Levi–Civita metric and obtain tetrad and the torsion fields. The tensor, vector, and the axial-vector parts of the torsion tensor are evaluated. It is found that the vector part lies along the radial direction only while the axial-vector vanishes everywhere because the metric is diagonal. Further, we use the teleparallel version of Moller, Einstein, Landau–Lifshitz, and Bergmann–Thomson prescriptions to find the energy-momentum distribution of this metric and compare the results with those already found in General Relativity (GR). It is worth mentioning here that momentum is constant in both of the theories for all the prescriptions. The energy in teleparallel theory is equal to the corresponding energy in GR only in the Moller prescription for the remaining prescriptions, the energy does not agree in both theories. We also conclude that Moller's energy-momentum distribution is independent of the coupling constant λ in the teleparallel theory.PACS Nos.: 04.20.–q, 04.20.Cv
Exact one-loop running couplings in the standard model
Authors: Chishtie F A , Lepage M D , McKeon D GC , Steele T G , Zakout I
Published: October 2008

Taking the dominant couplings in the standard model to be the quartic scalar coupling, the Yukawa coupling of the top quark, and the SU(3) gauge coupling, we consider their associated running couplings to one-loop order. Despite the nonlinear nature of the differential equations governing these functions, we show that they can be solved exactly. The nature of these solutions is discussed and their singularity structure is examined. It is shown that for a sufficiently small Higgs mass, the quartic scalar coupling decreases with increasing energy scale and becomes negative, indicative of vacuum instability. This behavior changes for a Higgs mass greater than 168 GeV, beyond which this couplant increases with increasing energy scales and becomes singular prior to the ultraviolet pole of the Yukawa coupling. Upper and lower bounds on the Higgs mass corresponding to new physics at the TeV scale are obtained and compare favourably with the numerical results of the one-loop and two-loop analyses with inclusion of electroweak couplings.PACS Nos.: 11.10.Hi, 14.80.Bn
A study of the energy dependence for the multiplicity of shower particles produced in a 16O–emulsion interaction in the framework of the Coulomb-modified Glauber model
Authors: Nour El-Din M.S.M. , Solite M E
Published: October 2008

The total reaction cross sections for the interaction of 16O with emulsion nuclei (16O–Em) at energies: 0.2, 2.1, 3.6, 14.6, 60.0, and 200.0A GeV have been calculated in the framework of the Coulomb-modified Glauber model. A similar calculation in case of proton–emulsion (p–Em) interactions is carried out at the same energies. For both types of interactions, the corresponding projectile and target participants beside the corresponding binary collisions have been calculated for the same energies. Then the averages of these quantities have been obtained. These averages have been used in the calculations of the corresponding average multiplicity of the shower particles (s-particles) in the case of the 16O–Em interaction. The agreement between the calculated total reaction cross sections and the corresponding experimental data is quite good. Also, a good agreement between the calculated average multiplicities of the shower particles and the corresponding experimental data has been obtained.PACS Nos.: 24.10.Cn, 24.10.Ht, 25.60.Dz
Motion of a spheroidal particle in a micropolar fluid contained in a spherical envelope
Authors: Saad E I
Published: October 2008

This paper investigates first the Stokes’ axisymmetrical translational motion of a spheroid particle, whose shape differs slightly from that of a sphere, in an unbounded micropolar fluid. A linear slip, Basset-type, boundary condition has been used. The drag acting on the spheroid is evaluated and discussed for the various parameters of the problem. Also, the terminal velocity is evaluated and tabulated for the slip, deformity, and micropolarity parameters. Secondly, the motion of a spheroidal particle at the instant it passes the centre of a spherical envelope filled with a micropolar fluid is investigated using the slip condition at the surface of the particle. The analytical expressions for the stream function and microrotation component are obtained to first order in the small parameter characterizing the deformation. As an application, we consider an oblate spheroidal particle and the drag acting on the body is evaluated. Its variation with respect to the diameter ratio, deformity, micropolarity, and slip parameters is tabulated and displayed graphically. Well-known cases are deduced, the wall effect is then examined and comparisons are attempted between the classical fluid and micropolar fluid.PACS Nos.: 47.45.Gx, 47.15.Gf, 47.50.–d
Development of quantum network based on multiparty quantum secret sharing
Authors: Ma H , Chen B , Guo Z , Li H
Published: October 2008

In this paper, we develop a quantum network with a mutual quantum secure direct communication scheme based on multiparty quantum secret sharing. This quantum network, assumed to contain clusters S, M, and D, shares a sequence of single photons and Greenberger–Horne–Zeilinger (GHZ) states. Each cluster is made of the same or similar quantum nodes gathered or occurring closely together. The feature of this scheme is that the communication between two clusters depends on the agreement of the third cluster. We also prove that such a quantum network is unconditionally secure.PACS Nos.: 03.67.–Dd, 03.67.–Hk, 89.70.–a
Transient behaviour of magnetic and electric fields at any height above an atmospheric duct
Authors: Abo-Seida O M , Pirjola R J
Published: October 2008

We model the atmosphere by a surface duct underlying a half-space. A derivation is given for the electromagnetic field created by a vertical magnetic dipole, in the half-space above the duct, with an arbitrary time-varying moment. The method used for the solution is essentially based on the application of two functional transforms. Starting from the wave equation for the magnetic field and applying a Laplace transform in time, we obtain a two-dimensional Fourier transform in the horizontal spatial coordinates leading to an integral representation of the solution of the wave equation in the transform space. The transient behavior of the magnetic-field strength at any distance above the duct is determined.PACS Nos.: 41.20Jb, 42.25Bs, 42.25Gy
Study of photonic band-gap structure in three component Fibonaccimultilayers
Authors: Mishra R K , Pandey P C
Published: October 2008

In this paper, photonic band-gap structures of three-component Fibonacci multilayers are presented for the first time with the help of reflection and transmission diagrams. Here, a general method (method of transfer matrices) is used to describe dispersion, reflection, and transmission spectral studies. Quantitative analysis for the distribution of allowed and forbidden bands for different generation numbers is also demonstrated. The effect of an imaginary value for the propagation vector Q as well as an increase in the size of the system on the existence of forbidden photonic bands in the case of normal radiation of light in these lattices is also studied.PACS Nos.: 71.23.Ft, 73.21.Ac, 78.20.Ci
Rayleigh waves in transversely isotropic thermoelastic diffusive half-space
Authors: Kumar R , Kansal T
Published: October 2008

The present investigation is devoted to the study of the propagation of Rayleigh waves in a homogeneous, transversely isotropic, thermoelastic diffusive half-space subjected to stress-free, thermally insulated and (or) isothermal, and chemical potential boundary conditions, in the context of the theory of coupled thermoelastic diffusion. Secular equations for surface-wave propagation in the media being considered are derived. The surface-particle paths during the motion are found to be elliptical, but degenerate into straight lines in case where there is no phase difference between the horizontal and vertical components of the surface displacements. The phase velocity; attenuation coefficient; specific loss of energy; and the amplitudes of surface displacements, temperature change, and concentration are computed numerically and presented graphically to depict the anisotropy and diffusion effects. Some special cases of frequency equations are also deduced from the present investigation. PACS Nos.: 62.20.–x, 62.20.D–, 62.20.de, 62.20.dj, 62.20.dq, 62.30.+d, 66.10.C–, 66.10.cd, 66.10.cg, 66.30.–h
Hydromagnetic instability of a resistive hollow jet
Authors: Radwan A E
Published: October 2008

The magnetohydrodynamic (MHD) stability criterion of a resistive hollow cylinder with respect to its capillary, pressure gradient, and electromagnetic forces is established. Numerous stability criteria are obtained as limiting cases from the present relation. The capillary force is destabilizing only for certain wavelengths to axisymmetric mode and stable to all other disturbances. There are three different cases for discussing the electromagnetic force (EMF) influence on the resistive hollow jet instability. As the fluid is with finite resistivity, the EMF does not have any influence on the capillary instability of a resistive hollow jet, however, the finite resistivity has a stabilizing tendency on the MHD hollow jet. As the fluid has infinite resistivity, the EMF is (de-)stabilizing according to restrictions. As the fluid is with zero resistivity, the EMF exerts an influence giving a sort of rigidity to the conducting fluid and that influence causes the bending and twisting of the lines of force in the fluid. Consequently, for a magnetic field of high intensity the capillary destabilization could be suppressed and stability arises.PACS No.: 47.17+e
The physical interpretation of non-Hermitian Hamiltonians and other observables
Authors: Geyer H B , Heiss W D , Scholtz F G
Published: October 2008

A recent surge of publications about non-Hermitian Hamiltonians has led to considerable controversy and — in our opinion — to some misunderstandings of basic quantum mechanics. The present paper scrutinizes the metric associated with a quasi-Hermitian Hamiltonian and its physical implications. The consequences of the non-uniqueness such as the question of the probability interpretation and the possible and forbidden choices of additional observables are investigated and exemplified by specific illustrative examples. In particular, it is argued that the improper identification of observables lies at the origin of the claimed violation of the brachistchrone transition time between orthogonal states. The need for further physical input to remove ambiguities is pointed out.PACS Nos.: 03.65.–w, 03.65.Ca, 03.65.Ta, 03.65.Xp
The algebraic Bethe Ansatz without the Yang–Baxter equation
Authors: Schmidt Jeffrey R
Published: October 2008

The algebraic Bethe Ansatz is carried out for models (dimer models on a hexagonal lattice) whose matrix of local Boltzmann weights fails to satisfy the Yang–Baxter equation. The operator algebra is constructed instead by a generalizable alternative process using only the coproduct decomposition of the operators. The new technique makes it possible to solve many lattice N-body models whose local Boltzmann weights fail to meet the algebraic requirements of the Yang–Baxter equation.PACS Nos.: 02.20.Uw, 24.10.Cn, 87.10.Hk, 05.20.–y
Potential-energy curves of the CH radical molecule under spin-orbit coupling
Authors: Song C , Han H , Zhang Y , Yu Y , Gao T
Published: October 2008

Potential energy curves for the ground and excited electronic states of the CH radical molecule were calculated employing spin-orbit multiconfiguration quasi-degenerate perturbation theory (SO-MCQDPT). The results of our present SO-MCQDPT calculation for the CH radical molecule indicate that the ground electronic state of X 2Π splits into lower X1 2Π1/2 and higher X2 2Π3/2Ω states. The excited electronic state of a 4Σ– splits into lower a1 4Σ–1/2 and higher a24Σ–3/2, and the excited electronic state of A 2Δ splits into lower A1 2Δ3/2 and higher A2 2Δ5/2. The spin-orbit splittings for the 2S+1Λ states X 2Π, a 4Σ–, and A 2Δ are determined to be 25.963, 0.016, and 0.992 cm–1, respectively. The splittings are in good agreement with the experimental data for X 2Π and A 2Δ , and there are no experimental data for a 4Σ–. The potential-energy curves for all calculated bound states of CH are fitted to an analytical potential-energy function in the large range of R = 0.06–0.55 nm, from which accurate spectroscopic parameters are derived. It is the first time that the eight Ω states (X1 2Π1/2, X2 2Π3/2, a1 4Σ–1/2, a2 4Σ–3/2, A1 2Δ3/2, A2 2Δ5/2, B2Σ–1/2, and C2Σ+1/2) generated from the five valence 2S+1 Λ states (X 2Π , a 4Σ–, A 2Δ, B 2Σ–, and C 2Σ+) among those dissociating up to H(2Sg)+C(1Dg) have been studied theoretically. In addition, the carbon atom was taken as an example to prove the validity of the SO-MCQDPT method. The agreement between calculated and observed spin-orbit coupling is vert good.

PACS Nos.: 31.15.aj, 31.15.xh, 71.70.Ej
An improved elastic–viscoplastic soil model
Authors: Kelln Curtis , Sharma Jitendra , Hughes David , Graham James
Published: October 2008

This paper develops an improved and accessible framework for modelling time-dependent behaviour of soils using the concepts of elasticity and viscoplasticity. The mathematical description of viscoplastic straining is formulated based on a purely viscoplastic and measurable phenomenon, namely creep. The resulting expression for the viscoplastic strain rates includes a measure of both effective stress and the corresponding volumetric packing of the soil particles. In this way, the model differs from some earlier viscoplastic models and arguably provides a better conceptual description of time-dependent behaviour. Analytical solutions are developed for the simulation of drained and undrained strain-controlled triaxial compression tests. The model is then used to back-analyze the measured response of normally consolidated to moderately overconsolidated specimens of a soft estuarine soil in undrained triaxial compression. The model captures aspects of soil behaviour that cannot be simulated using time-independent elastic–plastic models. Specifically, it can capture the dependence of stress–strain relationships and undrained shear strength on strain rate, the development of irrecoverable plastic strains at constant stress (creep), and the relaxation of stresses at constant strain.
An improved analytical solution to estimate the stress state in subvertical backfilled stopes
Authors: Li Li , Aubertin Michel
Published: October 2008

The increasing use of backfill in underground mines requires a better understanding of the interaction between the relatively soft fill material and the surrounding rock mass. In recent years, it has been shown that stresses in backfilled stopes can be estimated using an approach based on Marston’s arching formulation developed initially for buried conduits in trenches. However, despite its advantages, this approach has some shortcomings. For instance, it postulates that both the vertical and horizontal normal stresses are uniformly distributed across the opening width. Numerical investigations conducted by the authors have shown that this assumption is not always valid. This paper presents a modification to the Marston-based solution, which leads to a nonuniform vertical stress distribution across the opening. This modification of the analytical solution involves parameters that have been calibrated against some numerical modelling results. The same equations and parameters are then shown to provide a good representation of additional modelling cases for which the stress state is correctly predicted.
2D modelling of clogging in landfill leachate collection systems
Authors: Cooke A. J. , Rowe R. Kerry
Published: October 2008

A 2D model for predicting clogging of a landfill leachate collection system and subsequent leachate surface position (mounding) is described. A transient finite element fluid flow model is combined with a reactive, multiple-species finite element transport model. The transport model considers biological growth and biodegradation, precipitation, and particle attachment and detachment. It uses a geometrical relationship to establish porosity from the computed thickness of the accumulated clog matter and a relationship between the porosity and hydraulic conductivity of elements in the system. The model represents the flow path within the drainage layer in profile. An iterative method is used to solve for the new hydraulic heads, surface and internal nodal positions, and redistributed clog properties (clog quantity, porosity, hydraulic conductivity) for each element and for each time step. The porosity (and consequently hydraulic conductivity) of the media can therefore change spatially and temporally. The mesh is regenerated automatically each time step (including the addition or subtraction of nodes) taking into account allowable element aspect ratios, the interfaces between differing hydrostratigraphic layers, and static point sources and openings. An integrated alternate solution for very thin mounds is included. The application of the model is demonstrated using a hypothetical field case.
Measurement of small-strain shear modulus Gmax of dry and saturated sands by bender element, resonant column, and torsional shear tests
Authors: Youn Jun-Ung , Choo Yun-Wook , Kim Dong-Soo
Published: October 2008

The bender element method is an experimental technique used to determine the small-strain shear modulus (Gmax) of a soil by measuring the velocity of shear wave propagation through a sample. Bender elements have been applied as versatile transducers to measure the Gmax of wet and dry soils in various laboratory apparatuses. However, certain aspects of the bender element method have yet to be clearly specified because of uncertainties in determining travel time. In this paper, the bender element (BE), resonant column (RC), and torsional shear (TS) tests were performed on the same specimens using the modified Stokoe-type RC and TS testing equipment. Two clean sands, Toyoura and silica sands, were tested at various densities and mean effective stresses under dry and saturated conditions. Based on the test results, methods of determining travel time in BE tests were evaluated by comparing the results of RC, TS, and BE tests. Also, methods to evaluate Gmax of saturated sands from the shear-wave velocity (Vs) obtained by RC and BE tests were investigated by comparing the three sets of test results. Biot’s theory on frequency dependence of shear-wave velocity was adopted to consider dispersion of a shear wave in saturated conditions. The results of this study suggest that the total mass density, which is commonly used to convert Gmax from the measured Vs in saturated soils, should not be used to convert Vs to Gmax when the frequency of excitation is 10% greater than the characteristic frequency (fc) of the soil.
Sand–rubber mixtures (large rubber chips)
Authors: Kim H.-K. , Santamarina J. C.
Published: October 2008

Mixtures of small rigid sand particles Dsand large soft rubber particles Drare prepared at different volume fractions and tested to investigate their small-strain and zero-lateral strain responses (Dr /Ds≈ 10). Both data sets are simultaneously gathered in an oedometer cell instrumented with bender elements. Data are analyzed in the context of mixture theory and with the aid of numerical simulations. Results show that the sand skeleton controls the mixture response when the volume fraction of rubber particles is Vrubber ≤ 0.3, while the rubber skeleton prevails at Vrubber ≥ 0.6. The large size and incompressibility of rubber particles provides high stress-induced stiffness in the sand skeleton near the equatorial plane of rubber particles. The corresponding increase in local small-strain shear modulus Gmaxresults in earlier wave arrivals in mixtures with Vrubber ≤ 0.3 than in pure sand, while the quasi-static constrained modulus is highest in pure sand. The constrained modulus and shear wave velocity are power functions of the applied effective stress in all mixtures. Results from this study (Dr /Ds≈ 10) and from a previous complementary study with small rubber particles (Dr /Ds= 0.25) show that the development of internal fabric, particle level processes, and the associated macroscale response of sand–rubber mixtures depend on the relative size between the soft rubber chips and the stiff sand particles Dr /Dsand their volume fractions.
Cyclic strength of a natural liquefiable sand stabilized with colloidal silica grout
Authors: Díaz-Rodríguez J. A. , Antonio-Izarraras V. M. , Bandini P. , López-Molina J. A.
Published: October 2008

This paper summarizes the experimental results of a series of cyclic simple shear tests on liquefiable silty sand with and without sample improvement with colloidal silica grout. The objective of the paper is to evaluate the effectiveness of colloidal silica grouting in reducing the liquefaction potential of natural silty sand. Colloidal silica was selected as a stabilizing material due to its low viscosity, wide range of gel times, nontoxicity, and low cost. The soil tested in this experimental program is a poorly graded sand with 11.5% of nonplastic silt from the Port of Lázaro Cárdenas, México. Colloidal silica treated and untreated sand specimens show different pore pressure response and deformation behavior under cyclic loading in simple shear tests. The results indicate that, for a given initial relative density and initial effective vertical stress, liquefiable silty sand specimens stabilized with colloidal silica grout generally exhibit significant gain in liquefaction resistance compared with untreated specimens. It was also found that the colloidal silica grout reduces considerably the rates of pore pressure generation and shear strain of the silty sand specimens subjected to cyclic loading.
RECENT DEVELOPMENTS IN CHIRAL UNITARY DYNAMICS OF RESONANCES
Authors: OSET E. , GENG L. S. , GAMERMANN D. , VACAS M. J. VICENTE , STROTTMAN D. , KHEMCHANDANI K. P. , TORRES A. MARTINEZ , OLLER J. A. , ROCA L.
Published: October 2008

In this talk I summarize recent findings made on the description of axial vector mesons as dynamically generated states from the interaction of pseudoscalar mesons and vector mesons, dedicating some attention to the two K1(1270) states. Then I review the generation of open and hidden charm scalar and axial states. Finally, I present recent results showing that the low lying 1/2+ baryon resonances for S=−1 can be obtained as bound states or resonances of two mesons and one baryon in coupled channels dynamics.
HEAVY-LIGHT MESONS AND CHIRAL SYMMETRY
Authors: BARDEEN WILLIAM A.
Published: October 2008

The chiral structure of heavy-light mesons is explored with a particular focus on the nature of the DsJ charmed mesons. Theoretical predictions for the hadronic and radiative decays of these mesons are compared to recent experimental data.
LOW LYING SCALAR RESONANCES AND CHIRAL SYMMETRY
Authors: ZHENG HANQING
Published: October 2008

Current theoretical studies on the σ and κ resonances are reviewed. It is emphasized that all evidences accumulated so far are consistent with the picture that the σ meson is the chiral partner of the Nambu–Goldstone bosons in a linear realization of chiral symmetry.
SCALAR TETRAQUARK CURRENTS WITH APPLICATION TO THE QCD SUM RULE
Authors: CHEN HUA-XING , HOSAKA ATSUSHI , ZHU SHI-LIN
Published: October 2008

We study the light scalar mesons in the QCD sum rule. We construct both the diquark-antidiquark currents [Formula: see text] and the meson-meson currents [Formula: see text]. We find that there are five independent currents for both cases, and derive the relations between them. For the meson-meson currents, five independent currents are formed by products of color singlet [Formula: see text] pairs or color octet pairs. However, they can be related to each other, and the relations are derived. We obtain the masses of the light scalar mesons which are consistent with the experiments.
RADIATIVE AND STRONG DECAYS OF Ds-MESONS IN THE HADROGENESIS CONJECTURE
Authors: SOYEUR MADELEINE , LUTZ MATTHIAS F. M.
Published: October 2008

The recently discovered scalar [Formula: see text] and axial vector [Formula: see text] charmed strange mesons are predicted in the hadrogenesis picture. They are generated by coupled-channel dynamics involving the scattering of Nambu-Goldstone bosons off pseudoscalar and vector D(Ds)-meson ground-states. The interaction vertices are given by the leading order chiral Lagrangian and chiral corrections to order [Formula: see text]. To assess this dynamical picture further, the radiative and strong decays into the isospin-violating π0Ds and [Formula: see text] channels are calculated. A consistent picture of these decays emerges when the parameters are chosen in accordance with expectations from the heavy-quark symmetry and large N c limit of QCD and when light vector mesons are introduced explicitly in the radiative decay processes. More accurate data are needed to predict decay parameters reliably.
CHIRAL PERTURBATION THEORY STUDY OF THE AXIAL N → Δ(1232) TRANSITION
Authors: GENG L. S. , CAMALICH J. MARTIN , ALVAREZ-RUSO L. , VACAS M. J. VICENTE
Published: October 2008

We have performed a theoretical study of the axial Nucleon to Delta(1232) (N → Δ) transition form factors up to one-loop order in covariant baryon chiral perturbation theory within a formalism in which the unphysical spin-1/2 components of the Δ fields are decoupled.
CHARM MESONS AT FAIR
Authors: TOLÓS LAURA , RAMOS ANGELS , MIZUTANI TETSURO
Published: October 2008

The in-medium properties of charm mesons (D and [Formula: see text]) in a hot and dense matter are studied. A self-consistent coupled-channel approach is driven by a broken SU(4) s-wave Tomozawa-Weinberg interaction supplemented by an attractive isoscalar-scalar term. As medium effects, we include Pauli blocking, baryon mean-field bindings, and π and open-charm meson self-energies. The dynamically generated [Formula: see text] and [Formula: see text] resonances in the DN sector remain close to their free space position but acquire large widths. The resultant D meson spectral function, which shows a single pronounced quasiparticle peak close to the free mass that broadens with increasing density, also has a long low energy tail associated with smeared [Formula: see text], [Formula: see text] configurations. The low-density approximation for the [Formula: see text] is questionable already at subsaturation densities. We touch upon the implication of our study for J/Ψ suppression at FAIR.
FROM LATTICE QCD TO NUCLEAR FORCE
Authors: HATSUDA TETSUO , AOKI SINYA , ISHII NORIYOSHI , NEMURA HIDEKATSU
Published: October 2008

After a brief introduction to the phenomenological nucleon-nucleon (NN) potentials, the basic formulation of deriving the NN potential from lattice QCD simulations on the basis of the equal-time Bethe-Salpeter wave function is presented. The resultant non-local NN potential and its derivative expansion are discussed. Ongoing and planned studies on the lattice with quenched and full QCD simulations are summarized.
LATTICE QCD CALCULATION OF NUCLEAR FORCES
Authors: ISHII NORIYOSHI , AOKI SINYA , HATSUDA TETSUO
Published: October 2008

Quenched lattice QCD results of nuclear forces are presented. Inter-nucleon potentials are constructed from Bethe-Salpeter wave functions of two nucleon states by using a Schrödinger-type equation. The results of the central force in 1S0 channel posses the repulsive core at short distance as well as the attraction at medium distance, both of which are enhanced in the light quark mass region. A preliminary result on the tensor force is also presented with the central force in 3S1 channel.
EFFECTIVE FIELD THEORY OF THE SINGLE-NUCLEON SECTOR
Authors: SCHERER STEFAN
Published: October 2008

We address the issue of a consistent power counting scheme in manifestly Lorentz-invariant baryon chiral perturbation theory. We discuss the inclusion of vector mesons in the calculation of the nucleon electromagnetic form factors. We comment on the chiral expansion of the nucleon mass to order [Formula: see text].
χ-SU(3) BETHE SALPETER MODEL: EXTENSION TO SU(6) AND SU(8) SPIN-FLAVOR SYMMETRIES
Authors: NIEVES J. , GARCÍA-RECIO C. , SALCEDO L. L. , MAGAS V. , RAMOS A. , MIZUTANI T. , TOKI H.
Published: October 2008

Consistent SU(6) and SU(8) spin-flavor extensions of the SU(3) flavor Weinberg-Tomozawa (WT) meson-baryon chiral Lagrangian are constructed, which incorporate vector meson degrees of freedom. In the charmless sector, the on-shell approximation to the Bethe-Salpeter (BS) approach successfully reproduces previous SU(3) WT results for the lowest-lying s–wave negative parity baryon resonances. It also provides some information on the dynamics of heavier ones and of the lightest d-wave negative parity resonances, as e.g. the Λ(1520). For charmed baryons the scheme is consistent with heavy quark symmetry, and our preliminary results in the strangeness-less charm C = +1 sector describe the main features of the three-star JP = 1/2− Λc(2595) and JP = 3/2− Λc(2625) resonances. We also find a second broad JP = 1/2− state close to the Λc(2595).