bluuebunny/crossref_metadata_2025 huggingface dataset:
Causes of Soil Salinization: 1. A Basin in Southern Alberta, Canada
Authors: Hendry M. J. , Buckland G. D.
Published: August 2005

The cause of soil Salinization affecting 1700 ha of a basin in southern Alberta, Canada was examined. Water‐table data indicate that ground water recharges over a large diffuse area to the south of the salinized lands. Hydraulic‐head and hydraulic‐conductivity data and stream‐function modeling show that the recharging ground water travels laterally towards the salinized area in shallow, permeable beds of the Foremost Formation. The presence of an angular unconformity between the shallow, flat‐lying bedrock and the overlying Quaternary deposits causes the ground water to discharge at the salinized area. Calculated discharge rate to the salinized area ranges from 2 to 40 mm/yr.
The Role of Pumping Tests in Site Characterization: Some Theoretical Considerations
Authors: Butler James J.
Published: August 2005

Pumping tests are the primary means of estimating the large‐scale storage and transmissive properties of an aquifer for site‐characterization investigations. Most analyses of pumping‐induced drawdown are performed using either the Theis log‐log curve‐matching procedure or the approximate Cooper‐Jacob semilog method. These two procedures provide dissimilar estimates in nonuniform aquifers due to their emphasis on properties in different portions of a unit. The log‐log curve‐matching approach heavily weights the properties of local material, while the semilog procedure emphasizes the properties of material within the front of the cone of depression. The different emphasis of the two procedures results in log‐log parameters being more appropriate for estimating pumping‐well drawdown, while semilog parameters are better for estimating well yield. The magnitude of the difference between parameters estimated by the two approaches is a function of the degree of aquifer nonuniformity and the distance between the observation and pumping wells. The further the observation well is from the pumping well, the smaller the difference between the parameters. The difference between parameters estimated by slug tests and those estimated by pumping tests, on the other hand, will increase with this distance. Due to their emphasis on near‐well materials, slug‐test parameters may be of use in estimating pumping‐well drawdown when employed in a patchy aquifer model. In general, predictions of aquifer behavior can be improved by more careful application of the conventional techniques used in pumping‐test analyses.
Ground‐Water Contamination by High‐Density Immiscible Hydrocarbon Slugs in Gravity‐Driven Gravel Aquifers
Authors: Corapcioglu M. Yavuz , Hossain M. Akhter
Published: August 2005

In contrast to light hydrocarbons like gasoline that float on the water table, high‐density chlorinated hydrocarbons such as TCE and TCA released to the environment sink into the aquifer and remain at the bottom for extended periods of time. The migration of these hydrocarbons is generally governed by the vertical component instead of lateral transport as for low‐density hydrocarbons. The Buckley‐Leverett approach is extended to a two‐dimensional case to simulate the migration of a high‐density hydrocarbon displacing ground water in a highly pervious gravity‐driven natural‐gradient gravel aquifer. Governing equations are solved by modifying the USGS solute transport model (Konikow and Bredehoeft, 1978). The modification incorporates the fractional flow curves of water and their saturation derivatives in vertical and horizontal directions as functions of degree of water saturation. As an example, a contamination incident representing a TCE spill from a storage tank buried in the saturated zone is considered. Numerical results show that high‐density, low‐viscosity immiscible chlorinated hydrocarbons can travel deeper and further in contrast to lower‐density, higher‐viscosity compounds, and that the migration is dominated by gravity‐driven vertical flow until the plume reaches the lower boundary.
Quantitative Analysis for the Cleanup of Hydrocarbon‐Contaminated Soils by In‐Situ Soil Venting
Authors: Johnson Paul C. , Kemblowski Marian W. , Colthart James D.
Published: August 2005

The efficiency of any soil venting operation will depend significantly on three factors: vapor flowrate, vapor flow path relative to the contaminant distribution, and composition of the contaminant. Simple mathematical models were developed to be used as screening tools to help determine if soil venting will be a viable remediation option at any given spill site. The models relate the applied vacuum, soil permeability, and spill composition to the vapor flowrates, velocities, mass removal rates, and residual composition changes with time. In this report the screening models and some sample calculations are presented. The results illustrate the advantages and limitations of venting as a remediation tool, under both ideal and nonideal conditions.
Two Approaches to Design of Monitoring Networks
Authors: Spruill Timothy B. , Candela Lucila
Published: August 2005

Two different approaches to the design of a ground‐water‐quality monitoring network may be appropriate, depending on the type of information desired. First, where the objective is to determine what ground‐water‐quality characteristics are like in an area (statistical quantification of typical concentrations, as given by the mean or median, or percentage of wells exceeding various use standards), networks can be designed to provide estimates of known reliability using standard parametric and nonparametric statistical techniques. This approach can provide information adequate to perform general water‐quality assessments where the intention of the monitoring network is to provide data about general suitability of the water for various uses. Second, where the objective is to maximize areal ground‐water‐quality information, networks also can be designed using geostatistical techniques, such as kriging. This second approach would be appropriate when information is needed on where particular problem areas may exist.

Both approaches were applied to 1965 chloride data from a deep confined aquifer in the Llobregat delta near Barcelona, Spain. Traditional statistical techniques are demonstrated to design a network that would provide an estimated median chloride concentration. A method is introduced that can be used to determine the sample size necessary to describe any selected quantile with known precision. On the basis of 120 observations in the 1965 data set, between 13 and 25 wells would be necessary to estimate the median chloride concentration within 40 percent of the true median with 95‐percent confidence. Kriging, a geostatistical technique, was applied to the data set to determine the minimum number of wells necessary to include in the network to retain the essential spatial information of the original network. By use of this technique, the original network of 120 wells was reduced by 17.5 percent to 99 wells, while the standard error was increased by only 1 percent.

A comparison of these two approaches indicates that a network designed by use of geostatistical techniques generally will require larger sample sizes than networks designed by use of traditional techniques, but the geostatistical techniques can provide data adequate to describe both stochastic and spatial features of water‐quality variables. Detailed description of spatial variability requires many sample points for extremely variable data. On the basis of results presented in this paper, prediction errors for chloride concentrations in ground water at selected points in the Llobregat delta were as much as 300 percent. Nevertheless, even the modified network of 99 wells would produce statistical estimates adequate for most general water‐quality assessments, in addition to retaining the spatial information contained in the original 1965 data set.
Structural and functional evidence supporting a role for leptin in central neural pathways influencing blood pressure in rats
Authors: Montanaro Marisa S. , Allen Andrew M. , Oldfield Brian J.
Published: August 2005

Leptin, a peptide hormone normally associated with body weight homeostasis, is implicated in the generation of obesity‐induced hypertension. Administration of leptin increases sympathetic nerve activity and blood pressure; however, the neural circuity involved in this pressor effect is not clearly defined. In this review we describe experiments in which pseudorabies virus was injected into the heart, kidney and the vasculature within skeletal muscle to reveal the distribution of neurones in the hypothalamus that project to these cardiovascular tissues. This distribution is compared to the well‐documented distribution of leptin receptors. Finally we discuss microinjection studies designed to examine the effect of leptin, in these regions, on sympathetic nerve discharge and arterial blood pressure. Leptin injected directly into the ventromedial hypothalamus, arcuate nucleus and lateral hypothalamic area (particularly the perifornical area) increased lumbar sympathetic nerve activity. In addition, microinjection into the ventromedial hypothalamus and parvocellular paraventricular nucleus increased blood pressure. Our results demonstrate a discrete set of hypothalamic pathways that may underlie the involvement of leptin in obesity‐induced hypertension.
Central and peripheral contributions to obesity‐associated hypertension: impact of early overnourishment
Authors: Morris Margaret J. , Velkoska Elena , Cole Timothy J.
Published: August 2005

Obesity induced by a high‐fat diet was associated with increased tail‐cuff blood pressure in adult rats. The mechanisms underlying obesity‐related hypertension are unclear, but increased sympathetic activation most probably plays a role. Neuroendocrine alterations observed in obesity may influence both feeding patterns and blood pressure. Work from our laboratory has shown that chronic overfeeding in rats leads to changes in neuropeptide Y (NPY) and α‐melanocyte stimulating hormone (αMSH) in the hypothalamus. These peptides have central effects on blood pressure, indicating that obesity‐related changes in the CNS may impact on cardiovascular function. Population studies suggest that nutrition in early life can influence the subsequent risk of obesity and high blood pressure. To examine the impact of early postnatal overnutrition on blood pressure and adipose‐derived mediators, we adjusted rat litters to 3 or 12 pups (overnutrition and control, respectively). Pups raised in small litters were 15% heavier at weaning, and this intervention was associated with a modest elevation of blood pressure and body weight as adults (16 weeks). Animals raised in small litters had increased 11β‐hydroxysteroid dehydrogenase type 1 (11β‐HSD1) mRNA in white adipose tissue as adults, which may impact on cardiovascular function. Adjustment of diet after weaning, to 30% fat diet or standard chow, allowed comparison of the impact of different periods of overnourishment. Implementation of a high‐fat diet at weaning overcame the effect of litter size on body weight from 10 weeks of age. Blood pressure rose progressively with high‐fat feeding and was positively correlated with leptin and body weight. Chronic consumption of a high‐fat diet led to marked increases in leptin and insulin and modest increases in blood pressure, and impacts on brain transmitters implicated in the regulation of both appetite and blood pressure. Overnourishment during early postnatal development led to profound changes in body weight at weaning, which tended to abate with maturation. It also led to long‐term changes in some adipose‐derived mediators, possibly increasing cardiovascular risk.
Role of leptin in obesity‐related hypertension
Authors: Haynes William G.
Published: August 2005

Obesity in humans causes hypertension, myocardial hypertrophy and coronary atherosclerosis, and increased cardiovascular morbidity and mortality that is thought to be related to sympathetic overactivity. Leptin is an adipocyte‐derived hormone that acts in the hypothalamus to regulate appetite, energy expenditure and sympathetic nervous system outflow. One of the major mechanisms leading to the development of obesity‐induced hypertension appears to be leptin‐mediated sympatho‐activation. Leptin adversely shifts the renal pressure–natriuresis curve, leading to relative sodium retention. Although obesity is generally associated with resistance to the anorexic and weight‐reducing actions of leptin, our work has shown preservation of its sympatho‐excitatory and pressor actions. This selective leptin resistance of obesity, coupled with hyperleptinaemia, may play a critical role in the cardiovascular complications of obesity. Increased information about leptin and its mechanisms of actions should help the development of safe and effective pharmacological treatments of obesity and obesity‐related hypertension.
The neurobiology of human obesity
Authors: Eikelis Nina , Esler Murray
Published: August 2005

Earlier ideas that sympathetic nervous system activity is low in human obesity, contributing to weight gain through absence of sympathetically mediated thermogenesis, can now be discounted. The application of sympathetic nerve recording techniques and isotope dilution methodology quantifying neurotransmitter release from sympathetic nerves has established that the sympathetic outflows to the kidneys and skeletal muscle vasculature are activated in obese humans. The cause remains unclear. The adipocyte hormone, leptin, stimulates the sympathetic nervous system in rodents, but whether this applies in humans is uncertain. Cross‐sectional studies suggest a quantitative link exists between regional sympathetic nervous tone (most notably in the kidneys) and rates of leptin release, but definitive studies documenting that leptin administration activates the human sympathetic nervous system have not been done. What might be the clinical implications of these new findings? The demonstration that the suppressed sympathetic tone characterizing many experimental models of obesity does not exist in human obesity weakens the case for the use of β3‐adrenergic agonists as thermogenic agents to facilitate weight loss. Although the neurogenic character of obesity‐related hypertension is now established, whether antiadrenergic antihypertensive drugs are the preferred agents for blood pressure reduction has not been adequately tested. Multiple site central venous sampling, disclosing release of leptin into the internal jugular veins, led to the demonstration that the leptin gene is also expressed in the brain, in addition to adipocytes. Brain resistance to leptin has been inferred in human obesity, given that overweight is accompanied by high plasma leptin levels. The fact that the genes for leptin and its receptors are normally expressed in the brain in human obesity, and that release of leptin from the brain is actually increased, argues against this. Brain leptin release has the potential to override the peripheral, adipocyte leptin system.
Identification of Genes of VSH-1, a Prophage-Like Gene Transfer Agent of
Brachyspira hyodysenteriae
Authors: Matson Eric G. , Thompson M. Greg , Humphrey Samuel B. , Zuerner Richard L. , Stanton Thad B.
Published: August 2005

VSH-1 is a mitomycin C-inducible prophage of the anaerobic spirochete
Brachyspira hyodysenteriae
. Purified VSH-1 virions are noninfectious, contain random 7.5-kb fragments of the bacterial genome, and mediate generalized transduction of
B. hyodysenteriae
cells. In order to identify and sequence genes of this novel gene transfer agent (GTA), proteins associated either with VSH-1 capsids or with tails were purified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The N-terminal amino acid sequences of 11 proteins were determined. Degenerate PCR primers were designed from the amino acid sequences and used to amplify several VSH-1 genes from
B. hyodysenteriae
strain B204 DNA. A λ clone library of
B. hyodysenteriae
B204 DNA was subsequently screened by Southern hybridization methods and used to identify and sequence overlapping DNA inserts containing additional VSH-1 genes. VSH-1 genes spanned 16.3 kb of the
B. hyodysenteriae
chromosome and were flanked by bacterial genes. VSH-1 identified genes and unidentified, intervening open reading frames were consecutively organized in head (seven genes), tail (seven genes), and lysis (four genes) clusters in the same transcriptional direction. Putative lysis genes encoding endolysin (Lys) and holin proteins were identified from sequence and structural similarities of their translated protein products with GenBank bacteriophage proteins. Recombinant Lys protein hydrolyzed peptidoglycan purified from
B. hyodysenteriae
cells. The identified VSH-1 genes exceed the DNA capacity of VSH-1 virions and do not encode traditional bacteriophage early functions involved in DNA replication. These genome properties explain the noninfectious nature of VSH-1 virions and further confirm its resemblance to known prophage-like, GTAs of other bacterial species, such as the GTA from
Rhodobacter capsulatus
. The identification of VSH-1 genes will enable analysis of the regulation of this GTA and should facilitate investigations of VSH-1-like prophages from other
Brachyspira
species.
TRACKING CONTROL OF COMPLEMENTARITY LAGRANGIAN SYSTEMS
Authors: BOURGEOT JEAN-MATTHIEU , BROGLIATO BERNARD
Published: August 2005

In this paper we study the tracking control of Lagrangian systems subject to frictionless unilateral constraints. The stability analysis incorporates the hybrid and nonsmooth dynamical feature of the overall system. The difference between tracking control for unconstrained systems and unilaterally constrained ones, is explained in terms of closed-loop desired trajectories and control signals. This work provides details on the conditions of existence of controllers which guarantee stability. It is shown that the design of a suitable transition phase desired trajectory, is a crucial step. Some simulation results provide information on the robustness aspects. Finally the extension towards the case of multiple impacts, is considered.
ON THE VIBRATION OF THE EULER–BERNOULLI BEAM WITH CLAMPED ENDS DEFLECTION CONSTRAINTS
Authors: KRYS'KO V. A. , AWREJCEWICZ J.
Published: August 2005

Complex vibrations of an Euler–Bernoulli beam with different types of nonlinearities are considered. An arbitrary beam clamping is considered, and deflection constraints (point barriers) are introduced in some beam points along its length. The influence of a constraint, as well as of the amplitude and frequency of excitation on the vibrations is analyzed. Scenarios of transition to chaos owing to the introduced nonlinearities are reported.
TEMPORAL TRANSFORMATIONS AND VISUALIZATION DIAGRAMS FOR NONSMOOTH PERIODIC MOTIONS
Authors: PILIPCHUK V. N.
Published: August 2005

In this paper, a special nonsmooth transformation of time is combined with the shooting algorithm for visualization of the manifolds of periodic solutions and their bifurcations. The general class of nonlinear oscillators under smooth, nonsmooth, and impulsive loadings is considered. The corresponding boundary value problems with no singularities are obtained by introducing the periodic piecewise-linear (sawtooth) temporal argument. The Ueda circuit, that is Duffing's oscillator with no linear stiffness, is considered for illustration. It is shown that the temporal mode shape of the input can be responsible for qualitative features of the dynamics, such as transitions between the regular and random motions. The important role of unstable periodic orbits and their links with strange attractors are discussed.
HETEROCLINIC BIFURCATIONS AND OPTIMAL CONTROL IN THE NONLINEAR ROCKING DYNAMICS OF GENERIC AND SLENDER RIGID BLOCKS
Authors: LENCI STEFANO , REGA GIUSEPPE
Published: August 2005

A method for controlling nonlinear dynamics and chaos, previously developed by the authors, is applied to the rigid block on a moving foundation. The method consists in modifying the shape of the excitation in order to eliminate, in an optimal way, the heteroclinic intersections embedded in the system dynamics. Two different cases are examined: (i) generic block under small perturbations and (ii) slender block under generic perturbations, and they are investigated analytically either by a perturbation analysis (former case) or exactly (latter case). Two different strategies are proposed: (i) one-side control, which consists in eliminating the intersections of a single heteroclinic connection, and (ii) global control, which consists in simultaneously eliminating the intersections of both heteroclinic connections. The best excitations permitting the maximum distance between stable and unstable manifolds are determined in both cases. Finally, some numerical investigations aimed at highlighting meaningful aspects of system response under controlled (optimal) and noncontrolled (harmonic) excitations are performed.
A GLOBAL PERIOD-1 MOTION OF A PERIODICALLY EXCITED, PIECEWISE-LINEAR SYSTEM
Authors: MENON SANTHOSH , LUO ALBERT C. J.
Published: August 2005

The period-1 motion of a piecewise-linear system under a periodic excitation is predicted analytically through the Poincaré mapping and the corresponding mapping sections formed by the switch planes pertaining to the two constraints. The mapping relationship generates a set of nonlinear algebraic equations from which the period-1 motion is determined analytically. The stability and bifurcation of the period-1 motion are determined, and numerical simulations are carried out for confirmation of the analytical prediction of period-1 motion. An unsymmetrical stable period-1 motion is observed. This investigation helps us understand the dynamical behavior of period-1 motion in the piecewise-linear system and more efficiently obtain other periodic motions and chaos through numerical simulations. The similar methodology presented in this paper can be used for other nonsmooth dynamical systems.
LOW-COST CONTROL OF REPETITIVE GAIT IN PASSIVE BIPEDAL WALKERS
Authors: PIIROINEN PETRI T. , DANKOWICZ HARRY J.
Published: August 2005

Small, discrete, corrective adjustments to foot geometry in a class of bipedal passive walkers are employed to affect the local stability properties of a periodic reference gait. It is demonstrated that successful stabilization can be accomplished for otherwise strongly unstable motions of vertically constrained as well as entirely unconstrained model mechanisms. In particular, recent results by the authors on stabilization of repetitive motion in hybrid dynamical systems are implemented to formulate a rigorous analytical methodology for predicting the stability characteristics of the controlled system. It is demonstrated that these predictions can be explicitly obtained based entirely on knowledge of the local stability properties of the reference motion in the absence of control.
SHOCK ISOLATION THROUGH PASSIVE ENERGY PUMPING CAUSED BY NONSMOOTH NONLINEARITIES
Authors: GEORGIADIS F. , VAKAKIS A. F. , MCFARLAND D. M. , BERGMAN L.
Published: August 2005

We investigate shock isolation designs based on nonlinear energy pumping caused by nonsmooth stiffness elements. In particular, we numerically study the shock isolation properties of a primary linear system of two coupled nonconservative oscillators with weakly coupled attachments possessing clearance nonlinearities. Under shock excitation the nonlinear attachments (termed nonlinear energy sinks — NESs) can be designed to absorb a significant portion of the input energy, thus enhancing the shock isolation performance of the primary system. In contrast to the classical linear vibration absorber whose operation is restricted to narrowband frequency ranges, the NESs are capable of efficiently absorbing energies caused by transient broadband disturbances, a feature that facilitates their implementation in practical applications. Moreover, the nonsmooth nonlinearities considered in this work are easily implementable since they are realized by means of linear stiffness elements.
BIFURCATIONS IN HYBRID MECHANICAL SYSTEMS WITH DISCONTINUITY BOUNDARIES
Authors: CASINI PAOLO , VESTRONI FABRIZIO
Published: August 2005

The paper studies the dynamics of a stop-belt friction oscillator (SBO). The system consists of a visco-elastic oscillator which is dragged by a rough support moving with constant driving velocity and can collide with a rigid obstacle. The peculiarity of this system is that, in the phase space, it exhibits two different discontinuity boundaries. Nonsmooth responses are consequently observed with nonstandard attracting properties. The evolution of steady state limit sets as the position of the obstacle is varied is described. The nonsmoothness sets of the system and, in particular, the presence of discontinuity boundaries caused by friction and impacts, lead to nonstandard bifurcations which are studied here by means of analytical and numerical tools.
LYAPUNOV'S EXPONENTS FOR NONSMOOTH DYNAMICS WITH IMPACTS: STABILITY ANALYSIS OF THE ROCKING BLOCK
Authors: AGENO ALESSIO , SINOPOLI ANNA
Published: August 2005

The plane dynamics of a rigid block simply supported on a harmonically moving rigid ground is a problem which still needs investigating, although the matter has been the subject of much research since the last century. Unilateral contacts, Coulomb friction and impacts make the system hybrid as it reveals a mixed continuous and discontinuous nature. Thus, stability analysis requires the extension and adaptation of concepts with regard to variational-perturbative procedures. In particular, discontinuous systems exhibit discontinuities or "saltations" in the fundamental solution matrix which must be analyzed carefully. In this paper, the adaptation of numerical methods that permit us to obtain characteristic multipliers and Lyapunov's exponents for the rocking mode of the block will be tackled. Analytical methods are used for the linearized equations of motion; the results are compared with those in the scientific literature.
QUANTIFYING SMOOTH AND NONSMOOTH REGULAR AND CHAOTIC DYNAMICS
Authors: AWREJCEWICZ J. , DZYUBAK L.
Published: August 2005

This paper addresses two main paths of investigations. First, a new numerical method to trace regular and chaotic domains of any nonlinear system governed by ordinary differential equations is proposed. Second, the introduced approach is first testified using the well-known chaotic behavior of a Duffing oscillator and Lorenz system, and is then applied to analysis of discontinuous two-degree-of-freedom self-excited system with friction. Stick-slip and slip-slip chaos is reported, among others.
STOCHASTIC AND/OR CHAOTIC RESPONSE OF A VIBRATION SYSTEM TO IMPERFECTLY PERIODIC SINUSOIDAL EXCITATION
Authors: DIMENTBERG M. F. , IOURTCHENKO D. V.
Published: August 2005

A single-degree-of-freedom system with one-sided rigid barrier at its equilibrium position is considered. The system is subject to excitation by a sinusoidal-in-time force with random white-noise temporal variations of the excitation frequency. Whilst response analysis had been made previously for the resonant case, i.e. one with expected excitation frequency being close to an even integer multiple of the natural frequency of the system without barrier, the nonresonant case is considered in this paper which is well known to be prone to multiple bifurcations and chaos in the case of perfectly periodic excitation. A simple qualitative explanation of the corresponding phenomenon of frequency multiplication, or "breeding", is provided for this case based on a special piecewise-linear transformation of state variables, which permits to get rid of velocity jump for the transformed velocity. The influence of the imperfect periodicity is then studied by numerical (Monte-Carlo) simulation. It is shown that increasing intensity of the white-noise variations of the excitation frequency, or bandwidth of the excitation power spectral density (p.s.d.), may greatly reduce frequency content of the response with simultaneous increase of the overall response level. The excitation/system bandwidth ratio is identified as a key governing parameter.
COLOR SUPERCONDUCTIVITY AT MODERATE BARYON DENSITY
Authors: HUANG MEI
Published: August 2005

This article focuses on the two-flavor color superconducting phase at moderate baryon density. In order to simultaneously investigate the chiral phase transition and the color superconducting phase transition, the Nambu–Gorkov formalism is extended to treat the quark-antiquark and diquark condensates on an equal footing. The competition between the chiral condensate and the diquark condensate is analyzed. The cold dense charge neutral two-flavor quark system is investigated in detail. Under the local charge neutrality condition, the ground state of two-flavor quark matter is sensitive to the coupling strength in the diquark channel. When the diquark coupling strength is around the value obtained from the Fierz transformation or from fitting the vacuum bayron mass, the ground state of charge neutral two-flavor quark matter is in a thermal stable gapless 2SC (g2SC) phase. The unusual properties at zero as well as nonzero temperatures and the chromomagnetic properties of the g2SC phase are reviewed. Under the global charge neutrality condition, assuming the surface tension is negligible, the mixed phase composed of the regular 2SC phase and normal quark matter is more favorable than the g2SC phase. A hybrid nonstrange neutron star is constructed.
CONDITIONAL MOMENTS IN SPALLATION OF 6.4 TeV 32S NUCLEI IN NUCLEAR EMULSION
Authors: KAMEL S.
Published: August 2005

The conditional moments of the charge distributions of the projectile fragments produced in the electromagnetic dissociation of 200A GeV 32 S projectiles are obtained based on an individual component model. The correlations between the conditional moments and thus, the distributions of conditional moments are studied. The experimental data are compared with the simple Monte Carlo partition method.
NUCLEON–NUCLEUS OPTICAL POTENTIAL FROM HARD- AND SOFT-CORE INTERNUCLEON POTENTIALS
Authors: HAIDER WASI , SHARMA BHARTI , ROOK J. R.
Published: August 2005

We have compared the binding energy of nuclear matter and the nucleon–nucleus optical potential, calculated in Brueckner theory starting from both the soft-core Urbana V-14 and the hard-core Hamada–Johnston internucleon potentials. Our results show that the real central part of the optical potential calculated from V-14 is about 10 MeV deeper than from the hard-core potential in the energy region 1–200 MeV. This greater depth mainly comes from the internucleon S- and D-states. In these states, the V-14 and Hamada–Johnston potentials give different phase shifts, the V-14 being in better agreement with experimental data. This difference is further enhanced by the Pauli principle in the calculation of the optical potential. Our analysis of proton–40 Ca differential cross-section and polarization data, in the energy region 30–200 MeV, shows that the optical potential calculated using V-14 is in better agreement with the data as compared with the Hamada–Johnston potential.
A STUDY OF EXCITATION FUNCTIONS FOR SOME RESIDUES PRODUCED IN THE SYSTEM 14N+128Te IN THE ENERGY RANGE ≈ 64–90 MeV
Authors: UNNATI  , SHARMA MANOJ KUMAR , SINGH B. P. , PRASAD R. , GUPTA SUNITA , BHARDWAJ H. D. , SINHA A. K.
Published: August 2005

The excitation functions for eight reactions produced in the interaction of 14 N +128 Te have been measured in the energy range ≈ 64–90 MeV using the activation technique. To the best of our knowledge these measurements have been performed for the first time. The measured excitation functions are compared with theoretical calculations done using the computer programs ALICE-91 and PACE. The effect of the variation of various program parameters on calculated excitation functions have been studied. The present analysis indicates that complete fusion, incomplete fusion and pre-equilibrium emission processes play important roles in these reactions.
MICROSCOPIC CALCULATIONS IN NEUTRON MATTER
Authors: GAD Kh.
Published: August 2005

The properties of neutron matter are investigated in the framework of the extended Brueckner–Hartree–Fock approximation at zero temperature. Self-consistent calculations using different realistic interactions are reported for pure neutron matter. In this contribution, all the self-energies are calculated self-consistently. Using the self-energy, k-mass is evaluated using realistic NN interactions. Furthermore, the effect of hole–hole contributions is examined. We found that the hole–hole ladder brought about a non-negligible contribution.
APPROXIMATION OF THE STOCHASTIC RAYLEIGH–BÉNARD PROBLEM NEAR THE ONSET OF CONVECTION AND RELATED PROBLEMS
Authors: BLÖMKER DIRK
Published: August 2005

It is well known that complicated stochastic evolution systems near a change of stability are often dominated by slow modes. We rigorously approximate the evolution of the system by stochastic ordinary differential equations describing the amplitudes of the dominating modes on a slow time-scale.

In this paper we focus on equations with quadratic nonlinearity and give applications to the Rayleigh–Bénard problem and a model from surface growth perturbed by fractional noise.The unique existence of global solutions is not necessary.
ASYMPTOTIC DISTRIBUTIONS AND LARGE DEVIATIONS FOR ITERATED MAPS WITH AN INDIFFERENT FIXED POINT
Authors: THALER MAXIMILIAN
Published: August 2005

We consider two-to-one interval maps which are expanding except at an indifferent fixed point. Our purpose is to show that the iteration of the Perron–Frobenius operator displays interesting asymptotic behaviour if we stretch the underlying random variables in a suitable way. As an immediate probabilistic consequence we get a distributional limit theorem, closely related to an arc-sine law, or a large deviation type result, depending on whether the return index is less than or equal to 1.
ON STOCHASTICITY OF SOLUTIONS OF DIFFERENTIAL EQUATIONS WITH A SMALL DELAY
Authors: FREIDLIN MARK , WEBER MATTHIAS
Published: August 2005

We show that solutions of a class of differential equations with a small delay can be approximated, in a sense, by a stochastic process on a graph associated with the equation. This process moves as a deterministic motion inside any edge of the graph, but, after reaching an interior vertex of the graph, the process chooses one of the other adjacent edges to proceed there with a certain probability. These probabilities are calculated explicitly. The stochasticity is an intrinsic property of the differential equation with small delay.
Consequences of the Cretaceous/Paleogene Mass Extinction for Marine Ecosystems
Authors: D'Hondt Steven
Published: August 2005

▪ Abstract  One of the greatest mass extinctions in Earth's history occurred at the end of the Cretaceous era, sixty-five million years (Myr) ago. Considerable evidence indicates that the impact of a large asteroid or comet was the ultimate cause of this extraordinary event. At the time of mass extinction, the organic flux to the deep sea collapsed, and production of calcium carbonate by marine plankton radically declined. These biogeochemical processes did not fully recover for a few million years. The drastic decline and long lag in final recovery of these processes are most simply explained as consequences of open-ocean ecosystem alteration by the mass extinction. If this explanation is correct, the extent and timing of marine biogeochemical recovery from the end-Cretaceous event was ultimately contingent on the extent and timing of open-ocean ecosystem recovery. The biogeochemical recovery may in turn have created new evolutionary opportunities for a diverse array of marine organisms.
Phylogenomics
Authors: Philippe Hervé , Delsuc Frédéric , Brinkmann Henner , Lartillot Nicolas
Published: August 2005

▪ Abstract  The continuous flow of genomic data is creating unprecedented opportunities for the reconstruction of molecular phylogenies. Access to whole-genome data means that phylogenetic analysis can now be performed at different genomic levels, such as primary sequences and gene order, allowing for reciprocal corroboration of the results. We critically review the different kinds of phylogenomic methods currently available, paying particular attention to method reliability. Our emphasis is on methods for the analysis of primary sequences because these are the most advanced. We discuss the important issue of statistical inconsistency and show how failing to fully capture the process of sequence evolution in the underlying models leads to tree reconstruction artifacts. We suggest strategies for detecting and potentially overcoming these problems. These strategies involve the development of better models, the use of an improved taxon sampling, and the exclusion of phylogenetically misleading data.
Landscape Ecology: What Is the State of the Science?
Authors: Turner Monica G.
Published: August 2005

▪ Abstract  Landscape ecology focuses on the reciprocal interactions between spatial pattern and ecological processes, and it is well integrated with ecology. The field has grown rapidly over the past 15 years. The persistent influence of land-use history and natural disturbance on contemporary ecosystems has become apparent. Development of pattern metrics has largely stabilized, and they are widely used to relate landscape pattern to ecological responses. Analyses conducted at multiple scales have demonstrated the importance of landscape pattern for many taxa, and spatially mediated interspecific interactions are receiving increased attention. Disturbance remains prominent in landscape studies, and current research is addressing disturbance interactions. Integration of ecosystem and landscape ecology remains challenging but should enhance understanding of landscape function. Landscape ecology should continue to refine knowledge of when spatial heterogeneity is fundamentally important, rigorously test the generality of its concepts, and develop a more mechanistic understanding of the relationships between pattern and process.
Evolutionary Causes and Consequences of Immunopathology
Authors: Graham Andrea L. , Allen Judith E. , Read Andrew F.
Published: August 2005

▪ Abstract  Immune responses can cause severe disease, despite the role immunity plays in defending against parasitism. Indeed, immunopathology is a remarkably common cause of disease and has strong impacts upon both host and parasite fitness. Why has immune-mediated disease not been eliminated by natural selection? What constraints might immunopathology impose upon the evolution of resistance? In this review, we explore two major mechanistic causes of immunopathology in mammals and consider how such disease may have influenced immune system design. We then propose hypotheses that could explain the failure of natural selection to eliminate immunopathology. Finally, we suggest how the evolution of strategies for parasite virulence and host resistance may be shaped by this “double-edged sword” of immunity. Future work may reveal whether immunopathology constrains the evolution of resistance in all host taxa.
The Evolutionary Ecology of Gynogenesis
Authors: Schlupp Ingo
Published: August 2005

▪ Abstract  Most metazoans engage in recombination every generation. In theory this is associated with considerable cost, such as the production of males, so that asexual organisms, which do not pay this cost, should be able to invade populations of sexuals. Some asexuals depend on sperm of sexual males to trigger embryogenesis, a reproductive mode called gynogenesis. The genetic information of males is typically not used. Theory predicts that such mating complexes are short-lived and highly unstable. Sperm dependency is not only the defining feature of the biology of gynogenetic metazoans, it is also a major puzzle in evolutionary biology. Organisms that apparently combine disadvantages of both sexuality and asexuality are a serious challenge to theory. A number of questions about these systems are still unresolved.
Pollen Limitation of Plant Reproduction: Pattern and Process
Authors: Knight Tiffany M. , Steets Janette A. , Vamosi Jana C. , Mazer Susan J. , Burd Martin , Campbell Diane R. , Dudash Michele R. , Johnston Mark O. , Mitchell Randall J. , Ashman Tia-Lynn
Published: August 2005

▪ Abstract  Quantifying the extent to which seed production is limited by the availability of pollen has been an area of intensive empirical study over the past few decades. Whereas theory predicts that pollen augmentation should not increase seed production, numerous empirical studies report significant and strong pollen limitation. Here, we use a variety of approaches to examine the correlates of pollen limitation in an effort to understand its occurrence and importance in plant evolutionary ecology. In particular, we examine the role of recent ecological perturbations in influencing pollen limitation and discuss the relation between pollen limitation and plant traits. We find that the magnitude of pollen limitation observed in natural populations depends on both historical constraints and contemporary ecological factors.
Niche Conservatism: Integrating Evolution, Ecology, and Conservation Biology
Authors: Wiens John J. , Graham Catherine H.
Published: August 2005

▪ Abstract  Niche conservatism is the tendency of species to retain ancestral ecological characteristics. In the recent literature, a debate has emerged as to whether niches are conserved. We suggest that simply testing whether niches are conserved is not by itself particularly helpful or interesting and that a more useful focus is on the patterns that niche conservatism may (or may not) create. We focus specifically on how niche conservatism in climatic tolerances may limit geographic range expansion and how this one type of niche conservatism may be important in (a) allopatric speciation, (b) historical biogeography, (c) patterns of species richness, (d) community structure, (e) the spread of invasive, human-introduced species, (f) responses of species to global climate change, and (g) human history, from 13,000 years ago to the present. We describe how these effects of niche conservatism can be examined with new tools for ecological niche modeling.
BLIND ANALYSIS IN NUCLEAR AND PARTICLE PHYSICS
Authors: Klein Joshua R , Roodman Aaron
Published: August 2005

▪ Abstract  During the past decade, blind analysis has become a widely used tool in nuclear and particle physics measurements. A blind analysis avoids the possibility of experimenters biasing their result toward their own preconceptions by preventing them from knowing the answer until the analysis is complete. There is at least circumstantial evidence that such a bias has affected past measurements, and as experiments have become costlier and more difficult and hence harder to reproduce, the possibility of bias has become a more important issue than in the past. We describe here the motivations for performing a blind analysis, and give several modern examples of successful blind analysis strategies.
STRESS, FATIGUE, HEALTH, AND RISK OF ROAD TRAFFIC ACCIDENTS AMONG PROFESSIONAL DRIVERS: The Contribution of Physical Inactivity
Authors: Taylor Adrian H. , Dorn Lisa
Published: August 2005

▪ Abstract  Strategies to achieve ambitious targets for reducing road accidents ( 34 ) have largely focused on engineering and technological advancements, the modification of occupational demands, and, to a lesser extent, human factors. These factors include stress and psychological states; sleep, fatigue, and alertness; and health status. Physical activity appears to influence all these human factors but has not previously been systematically considered as a direct or indirect risk factor for driver accidents. This chapter provides an overview, within an evidence-based framework, of the impact each of these human factors has on driver performance and risk of at-work road traffic accidents and then examines how physical (in)activity may moderate and mediate these relationships. Finally, we consider practical implications for work site interventions. The review aims to offer an evidence base for the deployment of resources to promote physical activity, manage stress, facilitate sleep, reduce fatigue, and enhance alertness to improve physical and psychological health among professional drivers.
Acute and chronic effects of glucose and carbachol on insulin secretion and phospholipase C activation: studies with diazoxide and atropine
Authors: Yamazaki Hanae , Philbrick William , Zawalich Kathleen C. , Zawalich Walter S.
Published: August 2005

The acute and chronic effects of 20 mM glucose and 10 μM carbachol on β-cell responses were investigated. Acute exposure of rat islets to 20 mM glucose increased glucose usage rates and resulted in a large insulin-secretory response during a dynamic perifusion. The secretory, but not the metabolic, effect of 20 mM glucose was abolished by simultaneous exposure to 100 μM diazoxide. Glucose (20 mM) significantly increased inositol phosphate (IP) accumulation, an index of phospholipase C (PLC) activation, from [3H]inositol-prelabeled islets. Diazoxide, but not atropine, abolished this effect as well. Unlike 20 mM glucose, 10 μM carbachol (in the presence of 5 mM glucose) increased IP accumulation but had no effect on insulin secretion or glucose (5 mM) metabolism. The IP effect was abolished by 50 μM atropine but not by diazoxide. Chronic 3-h exposure of islets to 20 mM glucose or 10 μM carbachol profoundly reduced both the insulin-secretory and PLC responses to a subsequent 20 mM glucose stimulus. The adverse effects of chronic glucose exposure were abolished by diazoxide but not by atropine. In contrast, the adverse effects of carbachol were abolished by atropine but not by diazoxide. Prior 3 h of exposure to 20 mM glucose or carbachol had no inhibitory effect on glucose metabolism. Significant secretory responses could be evoked from 20 mM glucose- or carbachol-pretreated islets by the inclusion of forskolin. These findings support the concept that an early event in the evolution of β-cell desensitization is the impaired activation of islet PLC.
l-Arginine infusion increases glucose clearance during prolonged exercise in humans
Authors: McConell G. K. , Huynh N. N. , Lee-Young R. S. , Canny B. J. , Wadley G. D.
Published: August 2005

Nitric oxide synthase (NOS) inhibition has been shown in humans to attenuate exercise-induced increases in muscle glucose uptake. We examined the effect of infusing the NO precursor l-arginine (l-Arg) on glucose kinetics during exercise in humans. Nine endurance-trained males cycled for 120 min at 72 ± 1% V̇o2 peak followed immediately by a 15-min “all-out” cycling performance bout. A [6,6-2H]glucose tracer was infused throughout exercise, and either saline alone (Control, CON) or saline containing l-Arg HCl (l-Arg, 30 g at 0.5 g/min) was coinfused in a double-blind, randomized order during the last 60 min of exercise. l-Arg augmented the increases in glucose rate of appearance, glucose rate of disappearance, and glucose clearance rate (l-Arg: 16.1 ± 1.8 ml·min−1·kg−1; CON: 11.9 ± 0.7 ml·min−1·kg−1 at 120 min, P < 0.05) during exercise, with a net effect of reducing plasma glucose concentration during exercise. l-Arg infusion had no significant effect on plasma insulin concentration but attenuated the increase in nonesterified fatty acid and glycerol concentrations during exercise. l-Arg infusion had no effect on cycling exercise performance. In conclusion, l-Arg infusion during exercise significantly increases skeletal muscle glucose clearance in humans. Because plasma insulin concentration was unaffected by l-Arg infusion, greater NO production may have been responsible for this effect.