We demonstrate the detection of magnetic particles carriedby water in a continuous flow using an atomic magnetic gradiometer.Studies on three types of magnetic particles are presented: a singlecobalt particle (diameter ~;150 mum, multi-domain), a suspension ofsuperparamagnetic magnetite particles (diameter ~;1 mum), andferromagnetic cobalt nanoparticles (diameter ~;10 nm, 120 kA/mmagnetization). Estimated detection limits are 20 mum diameter for asingle cobalt particle at a water flow rate 30 ml/min, 5x103 magnetiteparticles at 160 ml/min, and 50 pl for the specific ferromagnetic fluidat 130 ml/min. Possible applications of our method arediscussed.

The chiral-odd generalized parton distribution (GPD), or transversity GPD, of the nucleon can be accessed experimentally through the photo- or electroproduction of two vector mesons on a polarized nucleon target, {gamma}{sup (*)}N {yields} {rho}{sub 1}{rho}{sub 2}N', where {rho}{sub 1} is produced at large transverse momentum, {rho}{sub 2} is transversely polarized, and the mesons are separated by a large rapidity gap. We predict the cross section for this process for both transverse and longitudinal {rho}{sub 2} production. To this end we propose a model for the transversity GPDH{sub T}(x,{zeta},t), and give an estimate of the relative sizes of the transverse and longitudinal {rho}{sub 2}cross sections. We show that a dedicated experiment at high energy should be able to measure the transversity content of the proton.

A numerical technique has been developed to simulate the structural responses of radioactive material packaging components requiring closure-tightening torque to the scenarios of the hypothetical accident conditions (HAC) defined in the Code of Federal Regulations Title 10 part 71 (10CFR 71). A rigorous solution to this type of problem poses a considerable mathematical challenge. Conventional methods for evaluating the residue stresses due to the torque load are either inaccurate or not applicable to dynamic analyses. In addition, the HAC events occur sequentially and the cumulative damage to the package needs to be evaluated. Commonly, individual HAC events are analyzed separately and the cumulative damage is not addressed. As a result, strict compliance of the package with the requirements specified in 10CFR 71 is usually demonstrated by physical testing. The proposed technique utilizes the combination of kinematic constraints, rigid-body motions and structural deformations to overcome some of the difficulties encountered in modeling the effect of cumulative damage in numerical solutions. The analyses demonstrating use of this technique were performed to determine the cumulative damage of torque preload, a 30-foot drop, a 30-foot dynamic crush and a 40-inch free fall onto a mild steel pipe.

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Chemical kinetic modeling has been used for many years in process optimization, estimating real-time material performance, and lifetime prediction. Chemists have tended towards developing detailed mechanistic models, while engineers have tended towards global or lumped models. Many, if not most, applications use global models by necessity, since it is impractical or impossible to develop a rigorous mechanistic model. Model fitting acquired a bad name in the thermal analysis community after that community realized a decade after other disciplines that deriving kinetic parameters for an assumed model from a single heating rate produced unreliable and sometimes nonsensical results. In its place, advanced isoconversional methods (1), which have their roots in the Friedman (2) and Ozawa-Flynn-Wall (3) methods of the 1960s, have become increasingly popular. In fact, as pointed out by the ICTAC kinetics project in 2000 (4), valid kinetic parameters can be derived by both isoconversional and model fitting methods as long as a diverse set of thermal histories are used to derive the kinetic parameters. The current paper extends the understanding from that project to give a better appreciation of the strengths and weaknesses of isoconversional and model-fitting approaches. Examples are given from a variety of sources, including the former …

We study the initial-state-radiation processes e{sup +}e{sup -} {yields} K{sup +}K{sup -}{pi}{sup +}{pi}{sup -}{gamma} and e{sup +}e{sup -} {yields} K{sup +}K{sup -} {pi}{sup 0}{pi}{sup 0}{gamma} using an integrated luminosity of 232 fb{sup -1} collected at the {Upsilon}(4S) mass with the BABAR detector at SLAC. Even though these reactions are dominated by intermediate states with excited kaons, we are able to study for the first time the cross section for e{sup +}e{sup -} {yields} {phi}(1020)f{sub 0}(980) as a function of center-of-mass energy. We observe a structure near threshold consistent with a 1{sup --} resonance with mass m=2.175 {+-} 0.010 {+-} 0.015 GeV/c{sup 2} and width {Lambda} = 58 {+-} 16 {+-} 20 MeV. We observe no Y (4260) signal and set a limit of {Beta}{sub Y{yields}{phi}{pi}{sup +}{pi}{sup -}} {center_dot} {Lambda}{sub ee}{sup Y} < 0.4 eV (90% confidence level), which excludes some models.

An understanding of processes affecting seepage into emplacement tunnels is needed for correctly predicting the performance of underground radioactive waste repositories. It has been previously estimated that the capillary and vaporization barriers in the unsaturated fractured rock of Yucca Mountain are enough to prevent seepage under present day infiltration conditions. It has also been thought that a substantially elevated infiltration flux will be required to cause seepage after the thermal period is over. While coupled thermal-hydrological-chemical (THC) changes in Yucca Mountain host rock due to repository heating has been previously investigated, those THC models did not incorporate elements of the seepage model. In this paper, we combine the THC processes in unsaturated fractured rock with the processes affecting seepage. We observe that the THC processes alter the hydrological properties of the fractured rock through mineral precipitation and dissolution. We show that such alteration in the hydrological properties of the rock often leads to local flow channeling. We conclude that such local flow channeling may result in seepage under certain conditions, even with nonelevated infiltration fluxes.

This paper demonstrates the use of coupled fluid flow andgeomechanical fault slip (fault reactivation) analysis to estimate themaximum sustainable injection pressure during geological sequestration ofCO2. Two numerical modeling approaches for analyzing faultslip areapplied, one using continuum stress-strain analysis and the other usingdiscrete fault analysis. The results of these two approaches to numericalfault-slip analyses are compared to the results of a more conventionalanalytical fault-slip analysis that assumes simplified reservoirgeometry. It is shown that the simplified analytical fault-slip analysismay lead to either overestimation or underestimation of the maximumsustainable injection pressure because it cannot resolve importantgeometrical factors associated with the injection induced spatialevolution of fluid pressure and stress. We conclude that a fully couplednumerical analysis can more accurately account for the spatial evolutionof both insitu stresses and fluid pressure, and therefore results in amore accurate estimation of the maximum sustainable CO2 injectionpressure.

Using 65 million {Upsilon}(4S) {yields} B{bar B} events collected with the BABAR detector at the PEP-II e{sup +}e{sup -} storage ring at the Stanford Linear Accelerator Center, they measure the color-favored branching fractions {Beta}({bar B}{sup 0} {yields} D{sup +}{pi}{sup -}) = (2.63 {+-} 0.05 {+-} 0.22) x 10{sup -3}, {Beta}({bar B}{sup 0} {yields} D*{sup +}{pi}{sup -}) = (2.79 {+-} 0.08 {+-} 0.18) x 10{sup -3}, {Beta}(B{sup -} {yields} D{sup 0}{pi}{sup -}) = (4.90 {+-} 0.07 {+-} 0.23) x 10{sup -3} and {Beta}(B{sup -} {yields} D*{sup 0} {pi}{sup -}) = (5.52 {+-} 0.17 {+-} 0.43) x 10{sup -3}, where the first error is statistical and the second is systematic. With these results and the current world average for the branching fraction for the color-suppressed decay {bar B}{sup 0} {yields} D{sup (*)0}{pi}{sup 0}, the cosines of the strong phase difference {delta} between the I = 1/2 and I = 3/2 isospin amplitudes are determined to be cos{sigma} = 0.860{sub -0.006-0.028}{sup +0.007+0.029} for the {bar B} {yields} D{pi} process and cos{sigma} = 0.917{sub -0.016-0.051}{sup +0.018+0.059} for the {bar B} {yields} D*{pi} process. The results for cos{delta} suggest that final-state interactions are presented in the D{pi} system.

Soil salinity is an important constraint to agricultural sustainability, but accurate information on its variation across agricultural regions or its impact on regional crop productivity remains sparse. We evaluated the relationships between remotely sensed wheat yields and salinity in an irrigation district in the Colorado River Delta Region. The goals of this study were to (1) document the relative importance of salinity as a constraint to regional wheat production and (2) develop techniques to accurately identify saline fields. Estimates of wheat yield from six years of Landsat data agreed well with ground-based records on individual fields (R{sup 2} = 0.65). Salinity measurements on 122 randomly selected fields revealed that average 0-60 cm salinity levels > 4 dS m{sup -1} reduced wheat yields, but the relative scarcity of such fields resulted in less than 1% regional yield loss attributable to salinity. Moreover, low yield was not a reliable indicator of high salinity, because many other factors contributed to yield variability in individual years. However, temporal analysis of yield images showed a significant fraction of fields exhibited consistently low yields over the six year period. A subsequent survey of 60 additional fields, half of which were consistently low yielding, revealed that this …

The authors have searched for the rare decay B{sup +} {yields} D{sub s}{sup +}{pi}{sup 0}. The analysis is based on a sample of 232 million {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II e{sup +}e{sup -} storage ring. They find 19.6 signal events, corresponding to a significance of 4.7 {sigma}. The extracted signal yield including statistical and systematic uncertainties is 20.1{sub -6.0-1.5}{sup +6.8+0.4}, and they measure {Beta}(B{sup +} {yields} D{sub s}{sup +}{pi}{sup 0}) = (1.5{sub -0.4}{sup +0.5} {+-} 0.1 {+-} 0.2) x 10{sup -5}, where the first uncertainty is statistical, the second is systematic, and the last is due to the uncertainty on the D{sub s}{sup +} decay and its daughter decay branching fractions.

The detection of moving objects in complex scenes is the basis of many applications in surveillance, event detection, and tracking. Complex scenes are difficult to analyze due to camera noise and lighting conditions. Currently, moving objects are detected primarily using background subtraction algorithms, with block matching techniques as an alternative. In this paper, we complement our earlier work on the comparison of background subtraction methods by performing a similar study of block matching techniques. Block matching techniques first divide a frame of a video into blocks and then determine where each block has moved from in the preceding frame. These techniques are composed of three main components: block determination, which specifies the blocks; search methods, which specify where to look for a match; and, the matching criteria, which determine when a good match has been found. In our study, we compare various options for each component using publicly available video sequences of a traffic intersection taken under different traffic and weather conditions. Our results indicate that a simple block determination approach is significantly faster with minimum performance reduction, the three step search method detects more moving objects, and the mean-squared-difference matching criteria provides the best performance overall.

Precise contact between epithelial cells and their underlying basement membrane is critical to the maintenance of tissue architecture and function. To understand the role that the laminin receptor dystroglycan (DG) plays in these processes, we assayed cell responses to laminin-111 following conditional ablation of DG expression in cultured mammary epithelial cells (MECs). Strikingly, DG loss disrupted laminin-111-induced polarity and {beta}-casein production, and abolished laminin assembly at the step of laminin binding to the cell surface. DG re-expression restored these deficiencies. Investigations of mechanism revealed that DG cytoplasmic sequences were not necessary for laminin assembly and signaling, and only when the entire mucin domain of extracellular DG was deleted did laminin assembly not occur. These results demonstrate that DG is essential as a laminin-111 co-receptor in MECs that functions by mediating laminin anchoring to the cell surface, a process that allows laminin polymerization, tissue polarity, and {beta}-casein induction. The observed loss of laminin-111 assembly and signaling in DG-/-MECs provides insights into the signaling changes occurring in breast carcinomas and other cancers, where DG's laminin-binding function is frequently defective.

An important aspect of plasma wake field accelerators (PWFA) is stable propagation of the drive beam. In the under dense plasma regime, the drive beam creates an ion channel which acts on the beam as a strong thick focusing lens. The ion channel causes the beam to undergo multiple betatron oscillations along the length of the plasma. There are several advantages if the beam size can be matched to a constant radius. First, simulations have shown that instabilities such as hosing are reduced when the beam is matched [1]. Second, synchrotron radiation losses are minimized when the beam is matched. Third, an initially matched beam will propagate with no significant change in beam size in spite of large energy loss or gain. Coupling to the plasma with a matched radius can be difficult in some cases. This paper shows how an appropriate density ramp at the plasma entrance can be useful for achieving a matched beam. Additionally, the density ramp is helpful in bringing a misaligned trailing beam onto the drive beam axis. A plasma source with boundary profiles useful for matching has been created for the E-164X PWFA experiments at SLAC.

OpenMP provides a portable programming interface for shared memory parallel computers (SMPs). Although this interface has proven successful for small SMPs, it requires greater flexibility in light of the steadily growing size of individual SMPs and the recent advent of multithreaded chips. In this paper, we describe two application development experiences that exposed these expressivity problems in the current OpenMP specification. We then propose mechanisms to overcome these limitations, including thread subteams and thread topologies. Thus, we identify language features that improve OpenMP application performance on emerging and large-scale platforms while preserving ease of programming.

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Nanoindentation has recently emerged to be the primary method to study the mechanical behavior and reliability of human enamel. Its hardness and elastic modulus were generally reported as average values with standard deviations that were calculated from the results of multiple nanoindentation tests. In such an approach, it is assumed that the mechanical properties of human enamel are constant, independent of testing parameters, like indent depth and loading rate. However, little is known if they affect the measurements. In this study, we investigated the dependence of the hardness and elastic modulus of human enamel on the indent depth. We found that in a depth range from 100 nm to 2000 nm the elastic moduli continuously decreased from {approx} 104 GPa to {approx} 70 GPa, and the hardnesses decreased from {approx} 5.7 GPa to {approx} 3.6 GPa. We then considered human enamel as a fiber-reinforced composite, and used the celebrated rule of mixture theory to quantify the upper and lower bounds of the elastic moduli, which were shown to cover the values measured in the current study and previous studies. Accordingly, we attributed the depth dependence of the hardness and modulus to the continuous microstructure evolution induced by nanoindenter.

Ion-induced beam instabilities and tune shifts are critical issues for the electron damping ring of the International Linear Collider (ILC). To avoid conventional ion trapping, a long gap is introduced in the electron beam by omitting a number of successive bunches out of a long train. However, the beam can still suffer from the fast ion instability, driven by ions that last only for a single passage of the electron bunches. Our study shows that the ion effects can be significantly mitigated by using multiple gaps, so that the stored beam consists of a number of relatively short bunch trains. The ion effects in the ILC damping rings are investigated using both analytical and numerical methods.

The Cabibbo-Kobayashi-Maskawa (CKM) matrix element V{sub ub} is a fundamental parameter of the Standard Model, representing the coupling of the b quark to the u quark. It is one of the smallest and least known elements of the CKM matrix. With the increasingly precise measurements of decay-time-dependent CP asymmetries in B-meson decays, in particular the angle {beta} [1, 2], improved measurements of the magnitude of V{sub ub} will allow for stringent experimental tests of the Standard Model mechanism for CP violation [3]. The extraction of |V{sub ub}| is a challenge, both theoretically and experimentally. Theoretically, the weak decay rate for b {yields} uev can be calculated at the parton level. It is proportional to |V{sub ub}|{sup 2} and m{sub b}{sup 5}, where m{sub b} is the b-quark mass. To relate the B-meson decay rate to |V{sub ub}|, the parton-level calculations have to be corrected for perturbative and non-perturbative QCD effects. These corrections can be calculated using various techniques: heavy quark expansions (HQE) [4] and QCD factorization [5]. They make use of specific assumptions and are affected by different uncertainties. It is therefore important to make redundant measurements by using several experimental techniques, and different theoretical frameworks. Experimentally, the principal challenge …

The needs for considering aqueous and sorption kinetics and microbiological processes arises in many subsurface problems, such as environmental and acid mine remediation. A general rate expression has been implemented into TOUGHREACT, which considers multiple mechanisms(pathways) and includes multiple product, Monod, and inhibition terms. In this paper, the formulation for incorporating kinetic rates among primary species into the mass balance equations is presented. A batch sulfide oxidation problem is simulated. The resulting concentrations are consistent with simple hand calculations. A 1-D reactive transport problem with kinetic biodegradation and sorption was investigated, which models the processes when a pulse of water containing NTA (nitrylotriacetate) and cobalt is injected into a column. The problem has several interacting chemical processes that are common to many environmental problems: biologically-mediated degradation of an organic substrate, bacterial cell growth and decay, metal sorption and aqueous speciation including metal-ligand complexation. The TOUGHREACT simulation results agree very well with those obtained with other simulators.

The prevention of deforestation and promotion of afforestation have often been cited as strategies to slow global warming. Deforestation releases CO{sub 2} to the atmosphere, which exerts a warming influence on Earth's climate. However, biophysical effects of deforestation, which include changes in land surface albedo, evapotranspiration, and cloud cover also affect climate. Here we present results from several large-scale deforestation experiments performed with a three-dimensional coupled global carbon-cycle and climate model. These are the first such simulations performed using a fully three-dimensional model representing physical and biogeochemical interactions among land, atmosphere, and ocean. We find that global-scale deforestation has a net cooling influence on Earth's climate, since the warming carbon-cycle effects of deforestation are overwhelmed by the net cooling associated with changes in albedo and evapotranspiration. Latitude-specific deforestation experiments indicate that afforestation projects in the tropics would be clearly beneficial in mitigating global-scale warming, but would be counterproductive if implemented at high latitudes and would offer only marginal benefits in temperate regions. While these results question the efficacy of mid- and high-latitude afforestation projects for climate mitigation, forests remain environmentally valuable resources for many reasons unrelated to climate.

This paper studies AMG (algebraic multigrid) methods that utilize energy minimization construction of the interpolation matrices locally, in the setting of element agglomeration AMG. The coarsening in element agglomeration AMG is done by agglomerating fine-grid elements, with coarse element matrices defined by a local Galerkin procedure applied to the matrix assembled from the individual fine-grid element matrices. This local Galerkin procedure involves only the coarse basis restricted to the agglomerated element. To construct the coarse basis, one exploits previously proposed constraint energy minimization procedures now applied to the local matrix. The constraints are that a given set of vectors should be interpolated exactly, not only globally, but also locally on every agglomerated element. The paper provides algorithmic details, as well as a convergence result based on a ''local-to-global'' energy bound of the resulting multiple-vector fitting AMG interpolation mappings. A particular implementation of the method is illustrated with a set of numerical experiments.

The interaction of supernova shocks and interstellar clouds is an important astrophysical phenomenon which can lead to mass-stripping (transfer of material from cloud to surrounding flow, ''mass-loading'' the flow) and possibly increase the compression in the cloud to high enough densities to trigger star formation. Our experiments attempt to simulate and quantify the mass-stripping as it occurs when a shock passes through interstellar clouds. We drive a strong shock using 5 kJ of the 30 kJ Omega laser into a cylinder filled with low-density foam with an embedded 120 {micro}m Al sphere simulating an interstellar cloud. The density ratio between Al and foam is {approx} 9. Time-resolved x-ray radiographs show the cloud getting compressed by the shock (t {approx} 5 ns), undergoing a classical Kelvin-Helmholtz roll-up (12 ns) followed by a Widnall instability (30 ns), an inherently 3d effect that breaks the 2d symmetry of the experiment. Material is continuously being stripped from the cloud at a rate which is shown to be inconsistent with laminar models for mass-stripping (the cloud is fully stripped by 80 ns-100 ns, ten times faster than the laminar model). We present a new model for turbulent mass-stripping that agrees with the observed rate and …

The East African and Ethiopian Plateaus have long been recognized to be part of a much larger topographic anomaly on the African Plate called the African Superswell. One of the few places within the African Superswell that exhibit elevations of less than 1 km is southeastern Sudan and northern Kenya, an area containing both Mesozoic and Cenozoic rift basins. Crustal structure and uppermost mantle velocities are investigated in this area by modeling Rayleigh wave dispersion. Modeling results indicate an average crustal thickness of 25 {+-} 5 km, some 10-15 km thinner than the crust beneath the adjacent East African and Ethiopian Plateaus. The low elevations can therefore be readily attributed to an isostatic response from crustal thinning. Low Sn velocities of 4.1-4.3 km/s also characterize this region.